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PEJ Vol. II, No. 1 June 1981

• Title: A locally designed on-off temperature controller
  Author: Emmanuel Dayo
  
• Title: A note on the analysis of pile groups
  Author: Dr. Salvador F. Reyes
  
• Title: A study for the development of a new compound gasification process of waste plastics and sludge
  Author: 
  Abstract: 

  A conventional gasification process of waste polyvinyl chloride (PVC) has a serious problem of producing a poisonous hydrogen chloride (HCl) which causes corrosion of a reactor wall or a heat exchanger. On the other hand, a gasification of a drainage sludge is sometimes meaningless since a calorific value of the produced gas is too low to be used as a gas fuel. In order to solve these problems, a new compound gasification process in which PVC and dry sludge are mixed and gasified together in the fluidized bed was proposed and tested by using a small scale fluidized bed. The important results were as follows:

  1. Hydrogen chloride gas (HCl) from PVC was significantly removed by slaked lime in the sludge when mole ratio of slaked lime to HCl was 5:1 in the bed. A slaked lime is often added to the sludge as a flocculant in the desiccation process.
  2. A calorific value of produced gas from PVC was 6000 to 7000 Kcal/Nm3 whilst that from sludge was around 2000 Kcal/Nm3 without slaked lime and 4000 to 5000 Kcal/Nm3 with slaked lime in the gasification temperature between 600oC to 800oC.
  
  
• Title: Alcohol as motor fuel-the “Alco-tipidâ€� way
  Author: Commodore A.C. Protacio
  Abstract: 

  The oil crisis of the 70�s created renewed interest in the use of fuel alcohol despite operational and technical problems experienced by many countries the past 70 years. In the Philippines this crisis motivated experiments which led to the development of alko-tipid. Significant properties of alcohol and gasoline provided design parameters for a simple vapor generating device working on engine vacuum evaporation, permitting the use of low grade alcohol, a renewable fuel, without the need for its dehydration nor any engine modification. Dynamometer and road tests confirmed significant reductions in fuel consumption, increased power and mileage, smoother and cleaner engine performance, and fuel cost savings of 20-25%. While alko-tipid could be a practical answer to the fuel crisis, the availability of alcohol is a temporary problem.

  
  
• Title: An introduction to experimental stress analysis
  Author: Geoffrey F. Chalmers
  
• Title: Building codes and regulations as they related to the improvement of the living conditions of the poor
  Author: Rosario Mallonga
  
• Title: Comparative performance test of a “Ducati IS-11â€� diesel engine using crude coconut oil
  Author: Dr. Ibarra E. Cruz
  Abstract: 

  A comparative test of the “Ducati-IS-11” single cylinder diesel engine showed no significant change in its performance when using either crude coconut oil or diesel fuel. In 18 runs using coconut oil, the average brake thermal efficiency was 23.7 percent at an average power output of 5.6 Bhp, compared with an average thermal efficiency of 23.4 percent in another 18 runs using diesel fuel at the same power output.

  
  
• Title: Computer application in civil engineering education
  Author: Jose Ma. De Castro
  
• Title: Designing a chemical engineering laboratory at a minimal cost
  Author: Gregorio C. Gervasio
  
• Title: Non-destructive testing and inspection
  Author: Tagumpay Cruz
  
• Title: Relevance of transducers in industrial electronics
  Author: Macario Cabrera
  
• Title: Reliability analysis of structural systems: A probabilistic approach
  Author: Dr. Peck-Tut Pua Uy
  
• Title: Strength for combined torsion, shear and bending
  Author: Dr. Romeo Estanero
  
• Title: Structure of the scientific research system in France
  Author: Dr. Bernard Baudelet
  
• Title: Sucro-Chemical
  Author: Hermenegildo Zayco
  
• Title: The technical panel for engineering education experience
  Author: Dr. Leopoldo V. Abis
  
• Title: Training tomorrow’s workforce today
  Author: Lemuel Miravalles
  

PEJ Vol. III, No. 1 June 1982

• Title: A survey of marine refrigeration
  Author: Thomas Vergel C. Jamir
  
• Title: Alcohol from Philippine mangrove swamps
  Author: Lourdes Go Redoloza
  
• Title: Alcohol production from nipa (Nypa Fruticans Wurmb): preliminary studies on ecology and chemistry
  Author: Rosenda G. Lorica and Miguel Fortes
  Abstract: 

  Preliminary investigations were made on the ecology of nipa groves and the chemistry of the plant sap at Paombong, Bulacan. Nipa shoots tended to grow faster with a decrease in temperature and an increase in rainfall (wet season). At another station, however, there was an inversion in the response of the plants to temperature. The alcohol content of the sap showed a marked decline by about 33% of the highest values obtained as the colder and rainy season progressed. Generally, shoot elongation and alcohol production were greater under the tidal conditions in Station 1, when compared to those in the more elevated, hence, drier conditions in Station 2. The extent of utilization of nipa and its products varied widely among the sites selected for the study.

  Post-fermentation analysis revealed that nipa sap contained mostly sugar and solids. Under natural conditions, the pH changed slightly within the 15-day period. However, there was a mean increase in the percentage of alcohol, particularly after the tenth day of fermentation. The tendency of the alcohol concentration to increase with the days continued regardless of the amount of inoculum (Saccharomyces cerevisiae) introduced into the medium.

  The problems encountered in the study are discussed and the necessity for more research on nipa is emphasized as an integral aspect of nonconventional energy-based development in the country.

  
  
• Title: Design of heat exchangers
  Author: Dr. Leopoldo V. Abis
  
• Title: Energy conservation in refrigeration and airconditioning
  Author: Teodorico P. Florida
  
• Title: Engineering and technological manpower survey in the Philippines
  Author: Dr. Isidro D. Carino and Edna P. Formilleza
  
• Title: Food preservation by refrigeration
  Author: Dr. Alicia O. Lustre
  
• Title: LPL: A problem-oriented language for linear programming
  Author: Evangel Quiwa
  
• Title: Maintenance in engineering laboratories
  Author: Macario P. Cabrera
  
• Title: Preparation of professional engineers for quality management
  Author: Dr. T.N. Goh
  Abstract: 
  By virtue of their involvement in product design, manufacture, testing and servicing, engineers constitute the majority of professionals whose work has direct relation to quality. However, the traditional approach to education of professional engineers tends to impact concepts and attitudes that do not necessarily lead to the kind of perspective needed for effective quality management. The deductive learning process in analysis and design, while necessary in general engineering education, is not sufficient for quality management which calls for appreciation and comprehension of uncertainty phenomena in the physical world, proficiency in inductive reasoning, and an adequate understanding of human behaviour. An appropriate orientation in university curriculum is necessary, as mass production of engineering graduates need to man the many technical positions created in a newly industrialized society, will not be sufficient by itself to guarantee the generation of consistently high quality products and services, the mark of a truly advanced economy. Other aspects of education for quality management are discussed, and possible measures are suggested for ensuring quality consciousness and competence in the new generation of engineers.
  
  
• Title: Pyrolysis of wastes
  Author: Teodorico F. Festin
  Abstract: 

  Results of a BED-UNIDO supported study on the pyrolysis of rice hulls, one of the most abundantly generated waste materials in the Philippines, showed the feasibility of converting these materials into charcoal, pyrolytic oil, and combustible gas.

  A manually-operated pyrolytic converter, originally designed at GIT, was locally fabricated and improved to process daily one ton of rice hulls. The design capacity could be attained only at high air flow rates (15 CFM and above). The average daily yields are: char, 15 kg; gas, 44 kg; and oil, 3.5 kg. The per cent energy recoveries from the pyrolytic products range from 80% to 90% for sixty-nine test runs.

  One of the most significant improvements on the system is the installation of a by-pass pipe from the reactor top leading to the demister. A higher pyrolytic oil (regardless of quality) and a better oil-water separation was effected resulting in two kinds of oil-low water condenser oil for possible fuel use, and a high water demister oil for use as a wood preservative, for economical reasons.

  The most promising use of a pyrolyzer is by integrating it with a rice mill. The pyrolytic products could provide the mechanical power for the mill and the heat to dry the grains and rice hulls. A calculation of the savings earned by installing a pyrolyzer near a rice mill showed that the investment for the additional unit can be paid-off with a period of one year.

  The integration of a pyrolyzer with a rice mill is one of the recommendations.

  
  
• Title: Skills of an effective administrator
  Author: Dr. Isidro D. Carino
  
• Title: Solar airconditioning systems
  Author: Aldwyn C. Santos
  
• Title: Solar crop dryer
  Author: Dr. Emerico Mendoza
  
• Title: Solar drying technologies
  Author: Dr. Emerico Mendoza
  
• Title: Thermoelectric refrigeration
  Author: Dr. Ruben A. Garcia
  
• Title: Wind energy development in the Philippines
  Author: Venancio L. Alcantara
  

PEJ Vol. III, No. 2 December 1982

• Title: A conceptual design of a computer-assisted procurement management system as applied to a construction project
  Author: Raul P. Rodriguez
  
• Title: A continuous mining system productivity model in terms of equipment reliability and availability.
  Author: Dr. Francisco L. Viray
  
• Title: A deformeter for model analysis of structure
  Author: Miguel B. Escoto, Jr.
  
• Title: A product mix optimization model
  Author: Leonardo P. Sangalang, Jr.
  
• Title: An improved method for optimizing the benefits of capacitor application in radial feeders
  Author: Arsenio A. Abellana
  Abstract: 

  The sizing, location and combination of capacitor banks to be placed in a radial distribution feeder for loss reduction and voltage control – is thoroughly investigated in this research work. The quantification of the benefits of voltage profile improvement and a thorough analysis for fixed and switched capacitor combinations are the main features of this work.

  Solution algorithms together with the corresponding computer programs and derivations of the equations are presented here. A mathematical model of a single-ended radial feeder, with real and reactive loadings assumed known at one hour intervals, was simulated in the IBM 360 UP engineering Computer.

  The results show that the consideration of monetary gain, due to voltage profile improvement of a radial feeder is very important aspect in the allocation of capacitors. This gain is even comparable to the savings due to peak-loss and energy-loss reductions. Best results are obtained when a combination of fixed and switched capacitors are used and located at different points along the feeder.

  
  
• Title: Combined forced and free convection in the entrance region of a horizontal pipe.
  Author: Morrison Sistuzo Montesclaros
  Abstract: 
  The effect of buoyancy on laminar forced convection in the entrance region of a uniformity heated horizontal pipe, where the velocity and temperature fields are developing simultaneously, is investigated for the case of Gr=5000. All the terms of the time-dependent governing equations are taken into account so that the results obtained can be applied to low Prandtl number fluids for which the results obtained from large Prandtl number assumptions are no longer valid. A novel iterative method is developed to solve nonlinear partial differential equations, and has proven to ensure stability and faster rate of convergence. The developing primary and secondary velocity profiles, developing temperature field, and local and average Nusselt numbers are presented to clarify the free convection effect. Values are compared with those obtained from pure forced convection.
  
  
• Title: Discrete system simulation
  Author: Armando dela Cruz
  
• Title: Effective computer planning
  Author: Dr. Roman V. Tuazon and Jose Ma. De Castro
  
• Title: Forecasting for business and technology management
  Author: Elisa C. Acio
  
• Title: Linear programming cases in the water resources engineering classroom: Formulation and implementation with the linear programming language (LPL) package.
  Author: Dr. Leonardo Q. Liongson
  
• Title: Pyrolytic conversion of coconut oil fatty acids into industrial solvents
  Author: Renato M. David
  Abstract: 

  Using a factorial experimental design, the effects of catalyst type and catalyst concentration on the pyrolytic conversion of coconut oil fatty acids into industrial solvents were studied. Results of the pyrolysis of fatty acids at 345oC and 200 psig for 21 hours using each of the following compounds as catalysts in quantities amounting to 1%, 5% and 10% of the total charge: FeCl3, lava, AlCl3 and Al203, indicated that the type of catalyst that was used affected the solvent yield significantly while the catalyst concentrations that were used did not. Further statistical analysis using Duncan’s multiple range test revealed that FeCl3 was the best catalyst, being significantly different from Al2O3, lava and AlCl3 which were not significantly different from one another. Duncan’s test likewise confirmed the result that the catalyst concentrations that were used had no significant effect on the solvent yields. The mechanism for converting coconut oil fatty acids into industrial solvents has been postulated to involve the conversion of fatty acids to hydrocarbons followed by the latter’s subsequent cracking. This mechanism satisfactorily accounts for the gases and distillate products that were obtained during the study.

  
  
• Title: Soil erosion control guidelines on urban lands
  Author: Dr. Romeo D. Bruce
  

PEJ Vol. IV, No. 1 June 1983

• Title: Alarm and safety shutdown interlock system: Balance between plant production and plant protection.
  Author: Remegio R. Lastrolo
  
• Title: An improved microwave radiometer for measurements on the human body
  Author: S. Osterrieder and G. Schaller
  Abstract: 

  The construction and performance of a 4 GHz-radiometer for measurements on the human body is presented.  The radiometer measures the temperature and emissivity simultaneously and independent of each other.  Experimental and theoretical results are given and the resolution of the radiometer is investigated.  

  
  
• Title: Computers – their growth and meaning for man
  Author: Miguel Ma. Varela, S.J., Ph.D.
  
• Title: Engineering education and training in a changing Philippine society
  Author: Marino M. Mena
  
• Title: Extracting highlights from the worldwide information industry: a management perspective for software engineering
  Author: Roman Tuason and Jose Ma. De Castro
  
• Title: Gel permeation chromatography of lignite hydroliquefaction products – an exploratory study
  Author: Angela D. Escoto
  
• Title: General formulate for flood frequency
  Author: G.L. Stevens and Pedro T. Templo
  
• Title: Information storage and retrieval systems
  Author: Loida O. Faustino
  
• Title: Kinematic analysis of three-link spatial mechanisms containing sphere-plane and sphere-groove pairs
  Author: Dr. Manuel V. Hernandez, Jr. G.N. Sandor and D. Kohli
  Abstract: 

  Kinematic pairs in a spatial mechanism are viewed either as allowing relative screw motion between links or as constraining the motion of the two chains of the mechanism connected to the two elements of the pair.  Using pair geometry constraints of the sphere-plane and sphere-groove kinematic pairs, the displacement, velocity and acceleration equations are derived for R-Sp-R, R-Sp-P, P-Sp-P, P-Sp-R and R-Sg-C three-link mechanisms.  For known values of the input variable, other variables are computed in closed form.  The analysis procedures are illustrated using numerical examples.

  
  
• Title: Management information systems – boon or bane to business?
  Author: Michel B. Azurin
  
• Title: On teaching different amplifiers using a “Tâ€� transistor model
  Author: Miguel T. Escoto, Jr.
  Abstract: 

  This paper presents a practical circuit approach in the analysis of an emitter-coupled differential amplifier pair.  Development and analysis center around parameter keywords like differential gain (AD), common mode gain (AC) and common mode rejection ratio (CMRR).  The Ebers-Moll Model is used to derive a “T” transistor model for signal analysis.

  
  
• Title: Six semesters of PSI: an evaluation
  Author: Dr. Edgardo S. Pacheco
  
• Title: Statistical analysis of a quantizer design algorithm
  Author: Dr. Efren F. Abaya
  Abstract: 

  Suppose that a sequence of probability distribution functions [Fn] converges weakly to distribution function F.  Does the sequence of optimal quantizers for the Fn’s converge to an optimal quantizer for F?  If so, do the respective distortions converge to the optimal distortion for F?  It is shown that uniform integrability of the cost function with respect to the sequence {Fn} is sufficient to obtain such convergence for mean-square distortion.  These questions are used to motivate a study of the strong consistency properties of optimal quantizer designs based on sampled data.

  
  
• Title: The development of multiple objective programming methods for forest land management planning: A survey and evaluation
  Author: B. Bruce Bare and Guillermo Mendoza
  Abstract: 

  Multiple objective programming (MOP) has undergone a rapid period of development in the 1970’s. Concurrently, increased land-use pressures have stimulated forest land management analysts to develop and utilize more sophisticated planning aids to address complex multiple use issues involving multiple objectives and decision-makers. In this paper, a selected set of MOP methodologies are reviewed and evaluated in terms of their utility and applicability as land management planning tools. The STEP method is selected as an appropriate technique and is applied to a forest land management problem. Two objective function weighting procedures are illustrated. Although no MOP technique by itself can resolve land management conflicts, the STEP method offers promise as a rational-systematic means of exploring alternative feasible solutions to the multiple objective forest land management problem.

  Multiple Objective Programming (MOP) or Multi-Criteria Decision Making (MCDM) is concerned with planning problems in which several conflicting objectives are to be optimized simultaneously. Multiple use forest planning exemplifies this situation because most forest land use planning problems involve a consideration of multiple conflicting goals and objectives such as: increased net revenue from timber resources, improved water quality, protection of wildlife, preservation of natural beauty, and increased recreational opportunities. The satisfactory attainment of these objectives is a major concern in forest land management planning. The applicability of MOP as a planning tool for forest land management planning is the primary motivation of this paper.

  
  
• Title: The Information Center
  Author: Wilfredo R. Pinga
  
• Title: The systems approach to project management
  Author: Alexander S. Cruz
  

PEJ Vol. IV, No. 2 December 1983

• Title: A probabilistic method of electric load analysis for ships
  Author: Dr. Reynaldo B. Vea
  
• Title: Alcohol fermentation
  Author: Dr. Ernesto J. del Rosario
  
• Title: Energy plantations
  Author: Dr. Frank H. Denton
  
• Title: Engineering education and training
  Author: Dr. Leopoldo V. Abis
  
• Title: On computing the input to a discretized linear system
  Author: Christian B. San Juan
  Abstract: 

  In some applications, there is the need to compute for the input signals of a linear system knowing the form of the output signal.  This is normally true in physiological and mechanical systems, especially in the field of robotics.  A simple way to do this is by discretizing the state equation.  The resulting equations are not only easy to manipulate but also amenable to computer solutions.

  
  
• Title: Philippine automated water information system: concepts and structure
  Author: Alejandro N. Resurreccion, Jr.
  Abstract: 

  The Philippine Automated Water Information system is a computer-based system for the storage, retrieval and analysis of water data.  It is aimed to provide a systematic and more efficient means of data accumulation and dissemination.  The system is divided into three components, namely:  Data Management component which is responsible for the creation and maintenance of its requisite files, Data Retrieval component which is responsible in satisfying the user’s request for data and the Data Analysis component which is responsible in providing the user with the results of processing and analyzing data.

  
  
• Title: Philippine experience in the commercial production of gasifiers
  Author: Jose A. Remulla
  
• Title: Philippine flood envelope curves derived from probability distribution of record maxima
  Author: Dr. Leonardo Q. Liongson
  Abstract: 

  The statistical properties of the largest or maximum observation in a series of annual extreme events are described and utilized in order to develop a statistical method for deriving flood envelope curves.  The statistical flood envelope method allows for the upward trend of the envelopes due to increasing record length, for regionalization and maximization of statistical parameters, and for transposition of exceptionally high observation.  The study aims to reconcile and unify the flood envelope method with the flood frequency method; as a result, both methods are governed by the same limitations.  Finally, statistical flood envelope curves for the Philippines are derived based upon the concepts and approaches developed.

  
  
• Title: Plunge pool scour studies using cohesive materials in a hydraulic model
  Author: Samuel R. Coran
  Abstract: 

  Rocks in situ do not slump and the traditional technique of using loose gravel in the model consequently cannot give a good representation of scour patterns in the prototype.  Thus, a refined modeling technique utilizing cohesive materials (a mixture of granular materials with a paste composed of clay binder, chalk powder, and water) to simulate the plunge pool geology is introduced.  This technique is applied to the plunge pool scour investigations in a 1:100 hydraulic scale model of a spillway project for the purpose of defining an adequate flip bucket toe protection system.  The methods, procedures, and results of the investigations are presented.

  
  
• Title: River Models: Physical vs. Mathematical
  Author: Peter P.M. Castro
  Abstract: 

  Rigid bed physical and mathematical modeling are each discussed at review level.  A brief historical background, an introduction to the theoretical basis for validity, and some sub-classifications and variants are included.  The two techniques are then compared, and some criteria for selection of method to use are mentioned.  It is suggested that problem definition should govern in the choice of models.  Recent trends that are radically changing the criteria are also mentioned.

  
  
• Title: Sediment control in irrigation canal intakes
  Author: Clarito C. Gonzales
  Abstract: 

  The control of sediments at irrigation canal intakes is a universal problem in the design of irrigation diversion systems. To facilitate the solution of the problem, the sediment load is first predicted using one of the numerous analytical equations.  From the computed estimate, a preliminary design of the sediment control scheme is made.  However, this initial design is not necessarily the optimum scheme.  In this regard, model studies serve as an aid in the evaluation of the sediment scheme.  Several model studies conducted and presently being conducted at the National Hydraulic Research Center are thus discussed to illustrate the evaluation procedure involved.

  
  
• Title: Synthesis of three-link function generators for coordinated rotations and translations
  Author: Dr. Manuel V. Hernandez, Jr.
  
• Title: Systems approach and engineering education
  Author: Antti Niemi
  
• Title: Waterhammer analysis in pump discharge lines caused by power failure
  Author: Perlita M. Arranz
  Abstract: 

  The safe design of a pumping system requires a knowledge of the maximum pump or motor speed, the minimum and maximum pressures that may occur in the system during transient conditions specifically after power failure.  Knowledge of the time at which the minimum head, maximum head, zero flow, zero pump speed and the maximum reverse flow occurs at the pump can be helpful for the proper design of discharge valve closure time and other waterhammer protection devices.  This paper presents the theoretical background of the waterhammer equations and the different methods of solutions to this unsteady flow phenomena that occur in pipelines.  It provides the head and discharge at any time after power failure of a specific point along the pipeline for given initial and boundary conditions.

  
  
• Title: Wave model for coastal structures
  Author: Enrico G. Gregorio
  Abstract: 

  Wave models as a planning and design tools are used to predict the influence of environmental conditions on a proposed harbour layout.  These models have to satisfy similarly criteria as described herein.  Factors such as wave climate, scale selection, hydrographic surveys, instrumentation and documentation influencing the design of the wave models are discussed.  The use of wave disturbance test and stability test in arriving at the optimum port layout and breakwater cross-section, respectively is also explained.

  
  

PEJ Vol. V, No. 1 June 1984

• Title: A logic function reduction and minimization algorithms for microcomputers
  Author: 
  Abstract: 

  Combinational logic forms the basis of any digital system when decomposed into its basic elements. Of particular significance in this area is the reduction and minimization of a combinational logic function. Besides being a necessary educational stepping stone towards more complex sequential logic systems, it still bears its importance today in fault analysis of digital systems, applications involving Field Programmable Logic Arrays (FPLAs), or chip-level design requirements for LSI and VLSI technology.

  This paper proposes and describes a departure from the more popular Quine-McCluskey computer solution in the form of an algorithm based on variable partitioning, combination generation and searching techniques for the prime implicants. Minimization is done by using a Zero-One Integer Programming model of the problem where the implicants and the logic function minterms or maxterms from a set of constraints to the problem and an objective function is used based on a pseudo-cost coefficient for each implicant requirement on fan-in and number of inverters.

  
  The algorithm was implemented in a computer program called BOZER (acronym for Boolean Zero-One Reduction) in a 64K microcomputer system using Microsoft’s MBASIC interpreter under a CDOS (CPM-enhanced) operating system. The present program can handle up to 13 state variables. Even if the implementation is only in a microcomputer system the processing time is still reasonable. It is predicted that for larger problems run on larger computer systems, the algorithm will show a significant reduction of processing time and memory requirement when compared to other algorithms written in the same language and run on the same machine. Finally, an algorithm expansion for the multi-output case is described.

  
  
• Title: An alternative formulation of the work energy principle
  Author: Dr. Edgardo S. Pacheco
  
• Title: An interpretation of the rural problem: towards a new approach to rural development
  Author: Alejnadro Lichauco
  
• Title: General equations for the lag time coefficient
  Author: G.L. Stevens and P.T. Templo
  
• Title: Plant cell cultures: some biotechnological applications and a proposed new bioreactor system
  Author: Dr. Wilfredo I. Jose
  
• Title: propeller selection and the stochastic sea
  Author: Dr. Reynaldo B. Vea
  
• Title: Solutions to systems of non-linear equations that arise in the kinematic synthesis of spatial mechanisms
  Author: N. Sandor, D. Eng., Dr. Manuel V. Hernandez, and Zhuang Xirong
  Abstract: 

  Determining the key dimensions of a mechanism for a prescribed performance is called the “synthesis” of the mechanism.  The prescribed performance is given by specifying position or motion specifications at “precision points”.  These specifications lead to a system of equations whose solutions give the desired key dimensions of the mechanism.  Synthesis for two or three positions generally results in a linear system of equations.  Synthesis for more than three positions leads to a non-linear system.  Different types of mechanisms give different forms of synthesis equations.  In this paper, two spatial mechanisms – a three-link mechanism with an intermediate higher pair of function generation and a five-link motion generator mechanism – are considered.

  
  
• Title: Technology and society
  Author: Antti J. Nieme
  
• Title: The dissolution characteristics of chrysocolla in NH3-(NH4)2CO3 solutions
  Author: Dr. Manolo G. Mena
  Abstract: 

  Chrysocolla samples were leached in ammonia-ammonium carbonate solutions of 0.25 to 6.00 M concentration total ammonia at a temperature range of 25oC to 55oC. The leaching curves for the fraction extracted, ά, as a function of time follow the expression:  which is the integrated form of the exponential rate law, assuming a linear dependence of the free energy of activation with the fraction extracted.  The initial kinetics follow the Langmuir-Hishelwood relation: rate   which is indicative of and adsorption process preceding chemical raction.

  
  
• Title: The plane simple shear testing of polycarbonate
  Author: Dr. Adolfo Jesus R. Gopez
  Abstract: 

  The plane simple shear test is applied to the case of polycarbonate, an amorphous polymer with a number average molecular weight of 15,600 g/mole and a degree of polydispersity of 1.85.  At room temperature, when polycarbonate is in the glassy state (Tg = 145oC), the shear stress-shear strain curve can be divided into five stages.  Stage I is characterized by an almost linear variation of the shear stress with the shear strain, and a gradual diminution of the slope towards the end of the stage.  Stage II corresponds to a drop in the shear stress even as the shear strain increases, while a linear portion of the curve with a small positive slope constitute Stage III.  A steeper portion of the curve corresponds to Stage IV.  Towards the end of the latte stage, the slope of the curve decreases.  In Stage V, a progressive reduction of the slope indicates the onset of rupture and a sudden drop in the stress level indicates the end of the test.  The yield point has been shown to correspond with the end of Stage I, and microscopic investigation indicates that a shear band forms during Stage II.  The band, which is initially short and narrow (0.1 mm), grows in length during Stage II and widens during Stage III.  The slope change between Stages III and IV indicates that the band occupies the entire calibrated part of the specimen.

  The effects of temperature and strain rate on the shear response was investigated.  At low temperatures the stress drop disappeared and a rigid behavior was observed, while at temperatures around and above Tg, a rubbery (elastomeric) response was observed.  The strain rate had a weaker although significant effect.  Increasing the strain rate increased the observed stress levels.  Reversal of the loading mode showed a reduced flow stress and the disappearance of the stress drop at yield.

  Using the test data, an empirical constitute flow equation for polycarbonate deformed in simple shear was derived.  A multiplicative law separating the effects of the different variables was shown to fit the data.  A mechanism of plastic deformation based on the nucleation and propagation of defects was proposed and an attempt was made to compare the shear test curve with that of a uniaxial tensile test for polycarbonate using the concepts of equivalent stress and strain.  Results of the comparison indicate that these tests cannot yet be derived from each other and that perhaps a better understanding of the basic mechanisms of plastic deformation in glassy amorphous polymers could lead to a more meaningful comparison of the tests.

  
  

PEJ Vol. V, No. 2 December 1984

• Title:  An integral – momentum analysis of the laminar boundary layer along a rectangular corner
  Author: Dr. Leonardo Q. Liongson
  Abstract: 

  An integral-momentum analysis is applied to the problem of the laminar boundary layer along a rectangular corner.  It involves an assumed self-similar velocity profile defined by functions with prescribed properties.  Two case examples are provided.  Reasonably good agreement is obtained between the results of the present study and the available numerical solution of previous workers on the problem.

  
  
• Title: A UCSD pascal P-Machine implementation on a minicomputer
  Author: Amante A. Mangaser
  
• Title: An interactive matrix arithmetic module (IMAM)
  Author: Dr. Salvador F. Reyes
  
• Title: Coal trade prospects in selected countries in East and Southeast Asia around the year 2000
  Author: Recto H. Puno
  Abstract: 

  Countries in East and Southeast Asia feel the need of resorting back to coal as a major source of energy.  Most of the projected requirements would have to be imported from outside the region which would entail a tremendous amount by the year 2000.  But economics of scale in ocean shipping exist and a substantial reduction of cost can be achieved using bigger vessels.  This paper looks into the possibility that economies of scale could justify construction of one or more transshipment depots in the region at which large loads from the supply sources are broken up and re-distributed in small vessels to small consumers.

  
  
• Title: Independent model method of aerial triangulation
  Author: Dr. Genaro T. Marzan
  
• Title: Kinetics of shear band formation and propagation in glassy polycarbonate deformed in simple shear .
  Author: Adolfo Jesus R. Gopez, Dr.-Ing
  Abstract: 

  A technique involving surface marking of simple shear test specimens was used to investigate the formation of shear bands in polycarbonate.  Plane simple shear testing was done to produce a single shear band in the test specimen.  Testing was done at ambient temperature (T = 23 + 1 oC) and at a constant reference shear strain rate  Results showed that the shear band formed at yield and then propagated in two stages: first by elongation and later by widening.  On the shear stress vs. shear strain curve, the elongation stage corresponded to a stress drop after yield and the widening stage corresponded to plastic deformation with a low apparent strain hardening rate.  Observation with markers showed that upon retesting, a previously deformed specimen no longer formed a shear band at yield.  Instead it deformed uniformly and homogenously.  End effects were also explored.  The results of this study confirm previously obtained results in the preliminary testing of polycarbonate.  Shear band formation and propagation were related to a defect theory, plastic deformation for glassy amorphous polymers.  According to this theory, plastic deformation takes place when there are enough elementary defects or when these defects are made to move at the right velocity.  Shear band formation was then explained to be the consequence of the difficulty with which elementary defects could be formed.

  
  
• Title: Outdoor test facility for solar flat – plate collectors
  Author: Henry J. Ramos and Edgardo S. Reyes
  Abstract: 

  An outdoor test facility based on the open-loop design has been developed for determining the efficiency of solar flat-plate collectors.  The applicability and adoption of the various published standards on collector testing like the ASHRAE, AFNOR, DIN/BSE, EIR and CSIRO under actual Philippine climatological conditions are discussed.  Features of the developed test facility are described and results obtained using one of the published standards are presented.

  
  
• Title: Strength evaluation of flexible securing systems for ship’s deck – stowed containers
  Author: Dr. Reynaldo B. Vea
  Abstract: 

  The seaway forces acting on ship’s on-deck containers, the elements of strength of containers and their securing gear and the equations characterizing the behavior of flexible securing systems are discussed.  An algorithm that generates points for a container stack weight diagram, for use by ship deck officers, is presented.

  
  

PEJ Vol. VI, No.1, June 1985

• Title: A computer program to determine the lateral critical speeds of flexible rotors
  Author: Alexander P. Paran and Willie C. Si
  Abstract: 

  This program determines by numerical methods the lateral critical speeds of a rotating shaft of circular cross section and of uniform density.  The core of this program uses the method developed independently by Prohl and Myklestad as adapted by J.W. Lund.  There is no limit to the number of critical speeds that the program can find, the only requirement being that the shaft in consideration be divided into a sufficient number of sections.  The program can handle either English units or the SI and the operator has a choice of entering some values in units of weight or units of mass.  Another feature of the program is the ability to plot the mode shapes of the rotor at the different critical speeds.

  
  
• Title: A new method for the kinematic analysis of planar four-bar mechanisms
  Author: Dr. Manuel V. Hernandez and Willie C. Si
  Abstract: 

   A convenient method for the analysis of planar four-bar mechanisms is achieved by applying the concept of direct linkage constraints and motion parameters based on the displacements of the mechanism.  Vectors are used extensively to make the derivation simpler and to make resulting analysis equations more compact.  The new method also eliminates the need to determine intermediate motion parameters.  Thus, only the motion parameters of interest are obtained directly and explicitly.  Higher order motion parameters are also derived from the basic linkage constraints.  The formulation of the method is shown and applied to the analysis of a crank-rocker and a slider-crank mechanism.

  
  
• Title: Analysis of defect structures in silicon solar cell materials
  Author: Dr. Marino G. Mena
  Abstract: 

  Three (3) solar cells fabricated from EFG ribbons were subjected to quantitative defect analysis on several surface planes.  The internal planes were observed by removing surface layers of silicon atoms by chemical dissolution.  The results show that the average dislocation pit density varies from one surface plane to another.  The procedures for chemical polishing and etching, as well as the process of quantitative effect analysis are also discussed.

  
  
• Title: Fermentation products from coconuts
  Author: Luz G. Paca
  
• Title: Fuels from coconut waste
  Author: Teodorico F. Festin
  
• Title: Long term prospects for energy prices
  Author: Dr. Serafin D. Talisayon
  
• Title: Soil incompressibility by “Mixedâ€� and penalty methods
  Author: Dr. Ronaldo I. Borja
  Abstract: 

  In this paper two numerical methods of treating soil incompressibility are discussed, namely: (1) solution by ‘mixed’ formulation and (2) solution by penalty formulation. The numerical methods presented herein are finite element-based and assume that in the no-flow (undrained) condition, the deformation and pore pressure behavior of a saturated soil medium can be analyzed either by considering a two-phase soil-water relationship or by a single-phase continuum formulation.

  
  
• Title: Strain-induced molecular orientation in sheared polycarbonate
  Author: Adolfo Jesus R. Gopez, Dr.-Ing
  Abstract: 

  Characterization of molecular orientation was done on polycarbonate samples previously deformed in plane simple shear.  Birefringence and extinction angle values and x-ray data indicated the presence of molecular orientation.  Measurements done on undeformed samples showed no evidence of orientation indicating that the orientation in the deformed sample is strained-induced.  A theoretical expression giving birefringence as a function of draw ratio was derived using the pseudo-affine hypothesis.  Good agreement was found with the birefringence data.  Comparison with samples deformed in uniaxial tension showed that for the same draw ratio, samples deformed in simple shear had higher birefringence.

  
  
• Title: The science and technology system in the Philippines in the Year 2000
  Author: Fortunato T. dela Peña
  

PEJ Vol. VI, No. 2 December 1985

• Title:  A unified method for MSP synthesis of planar four-bar function generators
  Author: Dr. Manuel V. Hernandez
  Abstract: 

  A review of the synthesis of planar four-bar function generators results in a more unified approach to the problem.  The question of number of parameters available for synthesis vis-à-vis the number of synthesis equations is reconciled.  Furthermore, the parameters used for synthesis are simply the coordinates of the vectors that define the mechanism.  The method developed gives very explicit equations in these parameters and with slight modifications and derivations become applicable for higher order synthesis.  Thus, the method is generalized for multiply-separated-position (MSP) synthesis of planar 4-bar function generators.

  
  
• Title: A new silver-zinc battery configuration: The use of a rotating vertical zinc electrode in the charging cycle
  Author:  Dr. Wilfredo I. Jose
  Abstract: 

  A new design of a silver-zinc cell is presented.  The system consists of a circular zinc electrode disk (negative electrode) which is rotated on the perpendicular axis passing thru its center and two circular disks with porous silver oxide coating (positive electrode) sandwiching the negative electrode.  The electrolyte is 40 percent potassium hydroxide solution.  The cell is charged with both the zinc electrode being rotated in a set of runs and stationary in another set.  The rotating electrode has a more uniform plating of zinc while the stationary electrode has dendritic and mossy growth and unevenly plated zinc.  The performance of the cells at the two different conditions are nearly identical.  Problems on the proper current distribution as well as electrical contact in the negative electrode were encountered.  The design can help increase the number of charge-discharge cycles of the cell.  However, the energy density is lower due to the space requirements of the rotating disk and accessories.

  
  
• Title: An integrated data input/output manager for microcomputers
  Author: Dr. Salvador F. Reyes
  
• Title: Computation of block error rates with randomly varying block sizes
  Author: Dr. Efren F. Abaya
  Abstract: 

  The block error rate (BLER) is a basic parameter of data communication channels which is usually computed on the assumption of independent and identically distributed bit errors and fixed block sizes.  This paper presents a method of computing block error rates when the block sizes are allowed to vary according to a known probability distribution.  It is shown that under some simple conditions the block error rate is relatively insensitive to the actual distribution or to the variance of the block length, and that it depends largely on the average block length.  Some analytic and numerical computations are presented to illustrate the method.

  
  
• Title: Corrosion of grinding media
  Author: Antonio F. del Rosario, Jr. and Dr. Manolo G. Mena
  Abstract: 

  An experimental technique in resolving wet grinding media wear into its mechanical and corrosive wear component is presented.  The results of the tests indicated that wet grinding media wear is approximately 46 percent mechanical wear and 54 percent corrosive wear

  
  
• Title: Development of coal-water fuel technology
  Author: Dr. Perfecto K. Guerrero
  
• Title: Digital controller for stepping motor-driven x-ray diffractometer
  Author: P.C. Naval, Jr. et. al
  Abstract: 

  Presented is a stepping motor controller for the Philips PW 1050 Vertical Goniometer featuring crystal-controlled scan rates of 4, 2, 1, ½, ¼, and 1/8 degrees per minute in the continuous scan mode, and step sizes of 0.005, 0.01, 0.02, 0.025, 0.05, 0.1, 0.2, and 0.5 degree when operated in the step scan mode.  A slew rate of 96 degrees per minute is provided for positioning purposes.

  The TTL-implemented design accommodates upgrading to higher levels of automation by a simple substitution of the control logic section.

  
  
• Title: Effects of pulsed operations on isothermal reactions in a CSTR
  Author: Angela D. Escoto
  Abstract: 

  This paper shall look into the possible effects of deliberate unsteady state processing brought about by introducing sinusoidal fluctuations to stable plants.  This practice is commonly referred to as PULSED operations.  Effects of input disturbances such as sinusoidal variations in feed rate and/or feed composition are reflected on the time average value of the system output.  It will be shown that the time average performance from periodic reactor operation is sometimes superior to that obtained from steady state processing.

  The following cases are considered:  (1) second order, irreversible reaction in an isothermal CSTR, 2A   B and (2) results of work done by other authors on complex reactions using parallel reactions, 2A   B and A   C, and consecutive reactions nA   B    C.

  
  
• Title: Frictional characteristics of non-woven geotextile-sand interface
  Author: Marte Gutierez, et.al
  Abstract: 

  The use of geotextiles is a recent innovation in soil stabilization.  For soil reinforcement applications, adequate geotextile-soil friction is necessary.  A high geotextile-soil friction will restrict displacements of soil around the geotextile and thus increase the strength of the soil itself.  This paper presents the results of tests performed to determine the frictional behavior of the  interface of sand and different types of non-woven geotextiles using a large direct shear testing machine.

  
  
• Title: The choice of technology for job development in a developing country
  Author: David Sycip
  

PEJ Vol. VII, No. June 1986

• Title:  A survey of properties of concrete aggregates from different sources near Metro Manila
  Author: Yoshide Yamao, Dr.-Ing., et al.
  Abstract: 

  The influence of aggregate properties on the performance of concrete is well documented in literature.  It is important, therefore, that information regarding their properties be determined prior to mixing of concrete.  This paper presents the results of tests performed to determine the physical properties of aggregates from different sources near Metro-Manila.

  
  
• Title:  The technoeconomic imperative-science and technology in genuine economic development
  Author: Eugenio M. Gonzales
  
• Title: A design synthesis for steel-hulled trawlers
  Author: Dr. Reynaldo B. Vea
  Abstract: 

  A computer-aided concept design synthesis for trawlers is developed.  Hull resistance is estimated from a previously published statistical analysis of trawler resistance data.  Construction costs are likewise approximated from published graphs, after updating where necessary.  Extensive curve fitting was done to make these existing information suitable for computerized procedure.   A numerical example relevant to Philippine conditions is given.

  
  
• Title: Computer and operations research in transportation
  Author: Rene S. Santiago
  
• Title: Finite elements studies of Ambuklao and Caliraya dams
  Author: Dr. Ronaldo I. Borja
  Abstract: 

  In the last two decades the finite element method has experienced tremendous growth in both theoretical developments and applications.  This paper explores the usefulness of this numerical method in the area of geotechnical engineering, incorporating into the implementation complex factors that cannot readily be handled by closed-form procedures such as dynamic behavior, material nonhomogeneities, plasticity, and creep.

  Subjects of the studies were two hydroelectric power-generating dams in the Philippines, namely, Ambuklao and Caliraya.  Eigenvalue studies were performed of Ambuklao Dam to investigate its dynamic response to the ground shaking induced by the earthquake of April, 1985.  A creep analysis of Caliraya Dam was also carried out using the conventional incremental plasticity theory and a recently developed constitutive model to predict the dam’s time-dependent deformation behavior in the next 40 years.

  
  
• Title: Pivotal technological problems confronting third world countries
  Author: Serafin D. Talisayon
  
• Title: The future of transportation energy use in the Philippines
  Author: Mark E. Hanson
  Abstract: 

  As the Philippines attains some progress in its program to reduce oil consumption and imports, the use of petroleum in the transportation industry will become an increasingly important factor to consider.  A set of microcomputer based spread sheet simulation models were used to estimate the impact of future economic trends and conservation actions. The simulation results indicated that an economic recovery and subsequent moderate growth would also lead to increased demand for petroleum.  On the other hand, economic stagnation combined with some conservation, would hold petroleum use fairly constant.  Specific conservation actions, such as efficiency standards, would significantly reduce the increase in petroleum use that would occur with the resumption of economic expansion.

  
  
• Title: The problems of the practice of science in the Philippines
  Author: Dr. Fabian M. Dayrit
  

PEJ Vol. VII, No. 2 December 1986

• Title: A functional equation in detection theory
  Author: Dr. Efren F. Abaya
  Abstract: 

  This paper discusses the solution of a functional equation describing equivalence of optimum detector structures for sampled data systems with independent samples.  It is shown that detectors based on a nonlinearity-summer-comparator structure are equivalent in the sense that they have the same acceptance and rejection regions only if their respective nonlinearities are linearly related.

  
  
• Title: Computer display of surfaces defined by functions in rectangular cylindrical, and spherical coordinates
  Author: Dr. Leonardo Q. Liongson
  Abstract: 

  Mathematical surfaces defined by functions in rectangular, cylindrical, and spherical coordinates are displayed as planar projections, either in orthographic or perspective form.  They appear as micro-computer graphics displays on a monitor screen or plotter paper.  The equations and procedures for coordinate transformations, orthographic and perspective projections, wireframe displays, and opaque displays with hidden-line removal are presented for the three coordinate systems.  Sample displays of surface are provided.

  
  
• Title: Economic analysis of investment proposals with dual rates of return
  Author: Forado L. Serrano
  Abstract: 

  Rate of return analysis of project proposals with dual rates of return often leads to vague conclusions.  This paper presents an empirical approach to investment situations which show two reversals in sign of the cash flow sequence.  In particular, the alternating cost-income-cost investment-situation which often produces dual rates of return is analyzed.

  A computer program was developed to determine when the final cost or costs in the alternating cost-income-cost investment-situation can be considered insignificant.  When the final cost or costs are found to be negligible, then the rate of return (ROR) assuming a final cost(s) of zero can be taken as the ROR of the particular investment proposal under consideration.

  
  
• Title: Finite element application to heat conduction problem
  Author: Dr. Ronaldo I. Borja
  Abstract: 

  In this paper a finite element solution to linear heat conduction problem is presented.  The formulation and numerical implementation described are shown to hold for other classes of diffusion problems such as fluid, electrical, and chemical solution, all of which are governed by differential equations of parabolic type.

  Steady state and transient conditions are both considered in the formulation, facilitating the solution to elliptic partial differential equations as well. The finite element techniques is used to discretize both the space and time domains.

  Also presented is an assessment of various time-stepping algorithms for transient problems with respect to accuracy and stability.  Five numerical examples are discussed.

  
  
• Title: Finite element application to heat conduction problem
  Author: Dr. Ronaldo I. Borja
  Abstract: 

  In this paper a finite element solution to linear heat conduction problem is presented.  The formulation and numerical implementation described are shown to hold for other classes of diffusion problems such as fluid, electrical, and chemical solution, all of which are governed by differential equations of parabolic type.

  Steady state and transient conditions are both considered in the formulation, facilitating the solution to elliptic partial differential equations as well. The finite element techniques is used to discretize both the space and time domains.

  Also presented is an assessment of various time-stepping algorithms for transient problems with respect to accuracy and stability.  Five numerical examples are discussed.

  
  
• Title: Long-term high temperature effects on a 1.25% Cr-0.5% Mo steel
  Author: Adolfo Jesus R. Gopez, Dr.-Ing and Eric C. Cutiongco
  Abstract: 

  Physical and metallurgical tests were used to reveal the effects of long-term exposure to high service temperatures on furnace tubes made of 1.25% Cr – 0.5% Mo steel.  The results of these tests together with an extrapolation of the creep-rupture curve were used to obtain an estimate of the remaining useful life beyond the usual design life of 100,000 hours for furnace tubes in a condition similar to those tested.

  
  
• Title: Stability of idealized slopes
  Author: Dr. Salvador F. Reyes
  
• Title: The waste utilization value – an original index for evaluating wastes
  Author: Dr. Wilfredo I. Jose
  Abstract: 

  The waste  utilization value (WUV), an original concept developed as a guide evaluating the economic value of wastes, is the value of a waste in monetary units per unit mass such as P/kg and could be negative, positive, or zero.  Pollutants and hazardous wastes have negative WUV, wastes that could turn in profits have positive WUV, and wastes that have no value but are not a pollution threat have zero WUV.  The values reported in this paper are from surveys and other available information.  Comprehensive surveys and calculations will serve as a data base for wastes.  The WUV is affected by several factors such as: economics, technical considerations, geology, ecological and environmental factors, geography, social factors, political factors, climate, time, etc.

  
  
• Title: Work measurement, improvement and standardization practices in the manufacturing sector
  Author: Fortunato T. dela Peña
  

PEJ Vol. VIII, No. 1 June 1987

• Title:  Industrial application of ergonomics
  Author: Sadao Horino
  
• Title: Applying the computer in the solution of electrical engineering problems
  Author: Miguel t. Escoto, Jr.
  Abstract: 

  This paper lists some of the potential areas where computers might be applied in the solution of electrical engineering problems.

  Specifically, it briefly describes the goals that were used as guides in the development of a computer oriented circuit analysis course (COCA) offered at the University of the Philippines, department of Electrical Engineering.  An example program demonstrates some points of interest pertinent to the applications of microcomputers for digital computations in basic circuit theory.

  
  
• Title: Architecture and engineering design for energy efficient low-cost housing
  Author: Geronimo V. Manahan F.U.A.P.
  
• Title: Heat transfer parameters for two-phase models of packed beds at low Reynolds numbers
  Author: Dr. Regano G. Benito
  Abstract: 

  A review, consideration and summary of the available correlations and data from various literatures were made for the parameters representing the mechanisms of heat transfer for fluid flows in packed beds at low Reynolds numbers.  These parameters are the axial dispersion coefficient, the effective solid phase conductivity, the particle and effective heat transfer coefficient.  Values of these parameters are required in the two-phase models of packed bed.  Due to lack of data from heat transfer experiments, the possibility of obtaining these parameters from mass transfer experiments was explored on the assumption of direct analogy between mass and heat transfer.

  
  
• Title: Kinematic synthesis and analysis of planar crank-slider and slider-slider mechanisms
  Author: Dr. Manuel V. Hernandez, Jr.
  Abstract: 

  Synthesis and analysis equations are formulated for the planar crank-slider and the slider-slider mechanisms using motion parameters based on displacements from the initial position of the mechanisms.  The synthesis equations are derived explicitly in terms of these parameters and also the parameters describing the mechanisms at their initial positions.  These synthesis equations are generalized for Multiply-Separated Position synthesis.  The solutions to the resulting systems of non-linear equations are shown for different cases of number of positions and unknowns and specified parameters describing the mechanisms at their initial positions.

  
  
• Title: Mechanical testing of solid polymers
  Author: Dr.-Ing Adolfo Jesus R. Gopez
  Abstract: 

   Standard tests for polymer mechanical properties are designed for use with easily available or easily constructed to allow widespread use of such tests.  Properties measured are often used for design purposes and these properties are threshold or external values.  No real effort is made to compare materials at intermediate testing stages.  Non-standard tests such as the tensile test at constant true strain rate and the plane simple shear test are therefore used to explore the plastic deformation behavior of solid polymers.  Strain rate and temperature effects have been explored to establish constitutive equations of flow for some polymers while the mechanism of plastic deformation in glassy polymers has been explored.  A comparison between amorphous and semi-crystalline polymers from the point of view of mechanical properties is made.  Some aspects of plastic instability in polymers are also discussed.

  
  
• Title: Microcomputers and static equilibrium
  Author: Dr. Salvador F. Reyes
  

PEJ Vol. VIII, No. 2 December 1987

• Title: A note on the computation of the hamming bound
  Author: Dr. Efren F. Abaya
  Abstract: 

  This paper derives a simple approximation to a binomial sum occurring in the Hamming Bound.  The approximation is easy to compute and quite accurate, even for modest values of the parameters involved.  The approximation permits easy calculation of the minimum number of parity bits required for t error correction.

  
  
• Title: Analytic solution of electromagnetic transient in a polyphase transmission system
  Author: Chen Jingke
  Abstract: 

  For the first time, this paper gives analytic solutions in the time-domain and natural frequencies of nonsymmetrical exciting systems after solving the matrix partial differential equations which describe electromagnetic behavior on polyphase lossy-transmission lines, the frequency-dependent parameters of which are considered, by using classical method strictly.  It is beneficial to the analysis of principle of protections based on traveling-wave and to the proposition of new criteria for protection.

  To verify the result, an example is taken which is offered by G.W. Swiftn (1) and solved by Bergeron’s method (2).  In the paper, several concepts are given. At the appendix, the correctness of solutions are proved mathematically.

  
  
• Title: Aseismic design provisions of selected building codes
  Author: Jose Ma. De Castro and Ulpiano Ignacio, Jr.
  
• Title: Environmental considerations in the design of energy efficient low-cost housing
  Author: Geronimo V. Manahan, F.U.A.P.
  
• Title: Flow of viscoelastic fluids through porous media
  Author: Luzviminda B. Moreno
  Abstract: 

  In the laminar flow of purely viscous non-Newtonian fluids through porous media, the effects of shear thinning on pressure drop are well understood and can be readily accounted for with appropriate modification of the Blake-Kozenly equation.  For viscoelastic fluids at large deformation rates, a gross increase in pressure drop over and above the prediction from the purely viscous theory has been observed.  This deviation was observed for two sets of viscoelastic fluids: aqueous polymer solutions (shear thinning elastic) and corn syrup-Separan mixtures (elastic but constant viscosity).

  A modified Rabinowitsch equation employing two geometric parameters, originally proposed by Kozicki et al. (1967), is used in conjunction with the Carreau viscosity equation to describe the anomalous flow resistance observed for the flow of aqueous polymer solutions through a packed bed.  For fluids which are highly shear thinning and elastic, a prediction based solely on the zero shear viscosity represents the upper bound of the viscous contributions.  The difference in pressure drop between the experiment and the upper bound prediction can be attributed to the elastic effect.

  The Deborah number, an elastic parameter based on Maxwellian relaxation time, does not uniquely correlate the observed excess flow resistance for the highly elastic but nearly constant viscosity fluids (Boger fluids).  An alternative correlation is proposed using a modified Deborah number based on the zero shear viscosity

  
  
• Title: Mixed logic systems
  Author: Rene Dos Remedios
  Abstract: 

  This paper presents, in an introductory manner, a method of creating and documenting digital circuit schematic diagrams.  The method emphasizes a technique of generating schematic diagrams which maximizes their semantic content.  This is achieved through the use of “natural” logic operators and through a convention which relieves the designer from having to think about final implementation details while designing the circuit.  This paper also aims to show that mixed logic is a viable alternative to the present methods of teaching digital electronics.  Unfortunately, the method, though widely accepted in industry is not given its due prominence by the academe.

  
  
• Title: Normalization in database design
  Author: Edgardo G. Atanacio
  Abstract: 

  The design of database files can be improved with the use of  normalization.  Normalization simplifies the structure of database files by grouping the components into simpler structures.  Such simple structures adapt better to changes or modifications to the database which are usually necessary to meet changing needs.  This paper describes the procedure of converting unnormalized files to the Third Normal Form.

  
  
• Title: The management of techno-transfer: The ITDI experiment
  Author: Rufino C. Lirag, Jr.
  

PEJ Vol. IX, No. 1 June 1988

• Title:  Some steps towards the development of low-cost typhoon resistant housing in the Philippines
  Author: Geoffrey N. Boughton
  Abstract: 

  Due to the high occurrence of typhoons in the Philippines, it is important that all housing be typhoon-resistant.  Following the passage of typhoon “Herming” in the Philippines, an extensive investigation of damage to low-cost housing was undertaken.  The principal aim of the activity was to isolate systematic problems in the structural action of low-cost housing and to make specific recommendations with respect to low-cost improvements to the buildings.  Three problems were highlighted and appropriate recommendations have been made.  An education programme will be mounted to publicize the recommendations.

  The paper outlines the structural damage caused by the typhoon and examines the recommendations made based on the preliminary data from the damage survey.

  
  
• Title: Design energy recovery systems with confidence – Use pinch technology targets
  Author: R.M. Wood
  Abstract: 

  In designing a network of heat exchangers for the recovery of waste heat, there is usually a “pinch” at which the minimum approach temperature difference limits energy recovery.  Pinch technology emphasizes the importance of utility and other targets, which are independent of the network design, and thus allow a very useful comparison with the requirements of actual networks.

  Methods for determining utility and area targets are surveyed.  These can be applied both to new designs as well as for determining the scope for energy conserving retrofits.  It is pointed out that significant improvements in utility targets can often be achieved by appropriate exploitation of process flexibility.  Thus, it is essential that for a successful application of these techniques, experts in the technology working closely with personnel who are also experts in the process being studied are required.

  
  
• Title: Highway earthwork program
  Author: Pedro T. Templo
  
• Title: On improving chemical engineering education in the Philippines
  Author: Wilfredo I. Jose and Jonathan L. Salvacion
  Abstract: 

  The task of improving chemical engineering education admits of two solutions.  We can first consider the needs of the non-academic sector, and then we can look at the problems from the viewpoint of the academe itself.  Various specific programs of action are proposed based on the experience of the University of the Philippines Department of Chemical Engineering.

  
  
• Title: The planning of LRT for Metro Manila
  Author: Rene S. Santiago
  Abstract: 

  This paper reviews the issues and activities that characterized the planning of the Light Rail Transit system of Metropolitan Manila.  A structured approach consisting of five major decision stages is postulated, then applied in discussing the current question: where is the next LRT line?

  Circumstances and planning methods differed for the two lines.  The first one, Taft-Rizal, went ahead somewhat so hurriedly that the normal sequences in the planning process were either compressed or skipped.  As a result, some advantages were foregone and unnecessary problems encountered during construction.  On the other hand, the planning and feasibility study for Line 2 were conducted on more firmer grounds such as: use of more up-to-date origin-destination data, examination of alternative alignments, and more comprehensive treatment of a wider range of issues.  A radial (Aurora Blvd.) and a circumferential (EDSA) line emerged as having the highest potentials.  These two options were then subjected to closer scrutiny, with the Aurora Line coming out on top.

  However, information gaps still remain to cast doubts on the advisability of pursuing the project at an early date.  A decision in favor of the Aurora Line will entail a government investment of US$220 million.  The project’s magnitude and impact are such that further studies can be justified – if only to address the affordability issue, the preparation of detailed engineering works, and the sourcing of subsidy, among others.

  
  
• Title: Time-variance spectrum & dynamic frequency response
  Author: Chen Jingke
  Abstract: 

  Based on the natural characteristic of transient signals, the new definitions, time-variance spectrum and dynamic frequency response, are presented.  As their applications, the spectrum analyses, the design method of a Finite Impulse Response (FIR) digital filter and frequency responses are used as the examples.  Both definitions are beneficial to practical uses in which a short time duration for processing transient signals is required.

  
  

PEJ Vol. IX, No. 2 December 1988

• Title: An experimental investigation of a toroidal engine combustion chamber
  Author: Edwin N. Quiros, Jack W. Adams and Prof. Philip S. Myers
  Abstract: 

  An exploratory study of a toroidal engine combustion chamber using a constant-volume bomb is reported in this paper. The toroidal shape design of the combustion chamber studied attempts to achieve continuous fresh air-fresh fuel mixing during injection and obtain desirable rates of air circulation using injected fuel momentum and combustion energy by varying the cross-sectional area of the combustion chamber.  High speed photographs of the combustion event were taken for flow visualization.  The pressure-time histories of the combustion process was also obtained to characterize combustion and the effects of changes in combustion chamber dimensions, injector position, ignition source, and charge density and temperature.  Preliminary results of the experiments undertaken are described. 

  
  
• Title: Application of structural dynamics in earthquake and wind engineering
  Author: D.Eng. Benito M. Pacheco
  Abstract: 

  Using minimal mathematics, extensive reference to the technical literature, and selected figures and tables, sate-of-the-art concepts structural dynamics are introduced as applied to seismic and wind-induced vibrations.  Physical interpretations of mathematical concepts, and practical concerns of civil-structural engineer are emphasized.  The presentation attempts to highlight some similarities and also sharpen certain contrasts between earthquake and wind effects.

  
  
• Title: Biomass hydrolysis
  Author: Dr. Wilfredo I. Jose
  
• Title: Hydrology and drainage for rural roads
  Author: Pedro I. Templo, Jr.
  
• Title: Quality management practices in three major Philippine manufacturing sectors
  Author: Fortunato T. dela Peña
  
• Title: State of the art applications of biotechnology in wastewater treatment
  Author: Dr. Wilfredo I. Jose
  Abstract: 

  Biological waste treatment processes such as the activated sludge and biomethanation use naturally occurring microorganisms.  With environmental biotechnology, the performance of these processes can be improved.  Special strains can be isolated to treat xenobiotics and other poorly degradable substances found in municipal sewage and industrial wastes.

  
  
• Title: The application of pinch technology heat exchanger network analysis at a crude oil refinery
  Author: Elino V. Crisostomo and Dr. Robert M. Wood
  Abstract: 

  This paper applies the principle of pinch technology to data obtained from a crude oil refinery.  The existing design is highly integrated and additional heat exchange surface had been added following the increase in oil prices in the last decade.  However, the targeting procedures identified possibilities for energy savings and a retrofit saving about 10% of the existing energy consumption with about a two-year payback is proposed.

  
  

PEJ Vol. X, No. 1 June 1989

• Title:  Performance tests on a modified vehicle fueled with a hydrous alcohol-gasoline blend
  Author: Dr. Ibarra E. Cruz
  
• Title: Analysis of error detection performance of a code with decimal check digits
  Author: Dr. Efren F. Abaya
  
• Title: Fuel substitution in automotive transport
  Author: Dr. Ibarra E. Cruz
  
• Title: Impact of power interruptions on national economy
  Author: Dr. Francisco L. Viray and Rowaldo R. del Mundo
  Abstract: 

  This paper shows that there is a significant correlation between energy consumption and national income or output.  Thus, it is inferred that power interruptions and shortages result to losses in national income.

  The study specifically deals with the impact of such power interruptions and shortages on the manufacturing industries, the sector in the economy that uses electric energy most intensively and which has one of the largest contributions to national income.

  To quantify the impact of power interruptions on national economy, a simplistic approach is presented.  Estimating graphs are generated for each industry group of the manufacturing sector as well as for the whole manufacturing industry.

  
  
• Title: Performance analysis of a combined updraft-stratified downdraft (CUSD) gasifier
  Author: Felipe D. Vinluan, Jr. and Dr. Ibarra E. Cruz
  Abstract: 

  The performance of the CUSD experimental gasifier was analyzed.  The experimental was conducted at the Mechanical Engineering (M.E.) Power Laboratory, College of Engineering, University of the Philippines, Diliman, Quezon City.

  With the use of ipil-ipil wood chips as fuel, the CUSD gasifier was proven to have a favorable performance as evidenced by the heating value of the gas, color of the flame, specific gasification rate and gasification efficiency.  The peak efficiency was obtained at L=0.15 which corresponds to an airflow ratio (downdraft/updraft) of 7.34.

  The CUSD gasifier possesses some desirable features which give it advantages over single-stage forced-draft gasifiers. These features include continuous gas production during fuel feeding, stable reaction zones even without tuyeres and movable grate, clean gas being produced with the proper combination of downdraft and updraft airflow rates, and effective removal of ash even without a movable grate.  If translated into the user’s benefits, these features could mean lower initial investment cost, easier maintenance and simpler operation than existing designs.

  
  

PEJ Vol. X, No. 2 December 1989

• Title: A study on porous asphaltic concrete mix and its value in pavement construction
  Author: Dominador S. Pagbilao
  Abstract: 

  The factors affecting the porosity of a porous asphaltic concrete mix was studied and the effect of these on its Marshall Stability was evaluated.  Based on the results of porosity and stability tests of several mixes, the value of a porous mix design to porous pavement construction is presented.

  
  
• Title: An analysis of a univariate multi-lag auto-regressive stochastic streamflow model
  Author: German T. Velasquez
  Abstract: 

  An analysis of a single-site auto-regressive multiple correlation is presented for the purpose of justifying a streamflow generator model.  The multi-lag analysis as presented by Fiering and Jackson (1971) is studied through its application to two streamflow records and through the use of different correlation coefficients. The simple hydrologic model by Fiering (1967) is also studied to determine its ability to mimic the actual flow instabilities.  Various model parameters are tested and their effect on the general characteristics of the resulting generator are determined.

  This analysis yielded the following conclusions:  The Fiering model for estimate correlation between flows does not mimic actual correlograms in the general sense.  Computer modeling presents instabilities in generation especially for AR models with flows lagged greater than seven.  Care must be taken in the choice of a random number generator so that the proper statistics will be preserved.  Data generation should only be made after a careful analysis of the stochastic part of the model because short term generations are greatly affected by this part of the model.

  
  
• Title: Coal-water slurry (CWS) optimization, flow and combustion tests at the University of the Philippines
  Author: Dr. Ibarra E. Cruz and Daniel L. Lim
  
• Title: Experimental investigation of the dynamic characteristics of vertical clamped-free cylindrical shell.
  Author: Bernardo A. Lejano
  Abstract: 

  An experimental procedure was developed to investigate the dynamic characteristics of vertical clamped-free cylindrical shell.  A cylindrical shell model made of rubber was constructed and tested in the dynamics laboratory of the Integrated Research and Training Center (IRTC), Technological University of the Philippines (TUP).  Forced vibration tests were conducted using a shaking table while free vibration was accomplished by applying an initial displacement.  The experimentally obtained dynamic characteristics show good agreement with the results using the finite element method.

  
  
• Title: Influence of geometrical parameters on the dynamic characteristics of thin vertical clamped-free cylindrical shell
  Author: Bernardo A. Lejano
  Abstract: 

  Recently the demand to build bigger and taller cylindrical shell structures has increased. This is accompanied with susceptibility to earthquake and wind vibrations. Hence, the design of such structures must ensure safety against these dynamic loads.  Dynamic performance of structures is reflected in the dynamic characteristics.  A finite element program suitable for the evaluation of the dynamic characteristics of cylindrical shell was developed for a 640K personal computer.  The influence of geometrical parameters on the dynamic characteristics of the cylindrical shell was investigated using the said computer program.

  
  
• Title: Marine applications of ferrocement
  Author: A.G. Trinidad and L. Robles-Austriaco
  Abstract: 

  Ferrocement has been accepted as a suitable building material for marine structures.  However, its potentials have not been fully utilized.  The reasons are manifold.  This study identifies and analyzes the problem areas, the possible solutions and the improvement of ferrocement marine technology.

  
  
• Title: Stochastic modeling and forecasting of reservoir inflows: A case study in the Philippines
  Author: Leonardo Q. Liongson
  Abstract: 

  This paper reports the general findings of a research project for stochastic modeling and forecasting of monthly and five-day inflows to the multi-purpose Angat reservoir.  The stochastic models investigated were the pure-runoff autoregressive-moving-average (ARMA) types, both of seasonal and nonseasonal forms, and either with or without estimation techniques of Kalman filtering, and rainfall-runoff ARMA-type of ARMAX (ARMA with exogenous input).  The research demonstrated the applicability of the best-selected models for forecasting dry-season low flows and wet-season moderate flows.  Recommendations for possible model improvements were also made.

  
  

PEJ Vol. XI, No. 1 June 1990

• Title: Chilled-water storages – An alternative solution to the problem of brownouts in the Philippines
  Author: A.M.B. Santos
  Abstract: 

  The problem of brownouts in the Philippines, specifically in Luzon, has been largely due to the high value of the peak power demand which our local utilities have difficulty supplying.  This paper discusses the merits to both the consumers and the electric utilities of installing chilled-water storages --- in addition to the benefit of reducing the possibilities of having power outages that these systems may potentially bring.  Written in a form that is readable by persons with varied backgrounds in engineering or allied fields.

  
  
• Title: Dissolution kinetics of chromite in hydrochloric acid solutions
  Author: Dr. Manolo G. Mena
  Abstract: 

  The Leaching response of chromite in hydrochloric acid solutions was studied.  The results show a 15 to 30 fold enhancement of iron over chromium extraction suggesting the feasibility of chemical beneficiation.  The extraction of iron was found to be logarithmic with time.  This was explained in terms of the strain-relief model involving a linear increase in the leaching activation energy as extraction proceeds.

  
  
• Title: Energy management in a wet process cement plant
  Author: F.A. Pecson and E.G. Echavez
  Abstract: 

  Cement manufacturers is one of the most energy intensive industries in the Philippines.  This paper discusses the overall approach undertaken by Bacnotan Consolidated Industries Cement Plant in reducing its fuel consumption from a level of 1700 kcal/kg of clinker to the current level of 1450 kcal/kg.  This approach was an application of systems analysis wherein a problem such as high fuel consumption is treated as a result of faults in a system where man, machines, materials and processes interact.  This is in contrast to the common approach of putting the blame entirely on the machines or on the materials, failing to see that for a problem such as this, one is dealing with a system.  Fishbone analysis was used to identify the various faults and corrective actions were then planned and undertaken.  Plant energy management organization, audit procedures as well as the system improvements which lead to improved fuel consumption are likewise discussed in the paper.

  
  
• Title: Research needs in flood control: Metro Manila and Laguna Lake Region
  Author: A.A. Alejandrino, S.R. Coran and P.P. M. Castro
  Abstract: 

  The perennial floods in Metro Manila and other towns in the Laguna Lake Region have been attributed to a number of factors.  The need for a comprehensive research program is discussed in order to determine the degree of influence of these factors as they involve not only local but also regional considerations.  The program includes development of the guidelines that would minimize the damaging effects of floods and would also rationalize the expenditures in coping with the flood problem

  
  
• Title: Wood gasification for heat and power – The Philippine experience
  Author: Ibarra E. Cruz
  Abstract: 

  The technology of wood gasification for heat and power for heat and power in the Philippines is discussed, starting with research and development activities in 1968 in several institutions in the country (notably the University of the Philippines), the commercialization efforts to propagate wood charcoal gasifiers by the Gasifier and Equipment Manufacturing Corporation (GEMCOR) in 1981, the monitoring of performance of several gasifier-engine systems in actual field operation, a study commissioned by the World Bank in 1983, culminating with a survey of 64 gasifier installations and interviews with 29 gasifier owners in 1985 to determine the problems and hindrances to widespread use of gasifiers in the country.  A number of gas producer systems are described and operational data presented.  Experiences in marketing of the systems are recounted and reasons for the failure to propagate wide use of the technology are evaluated.

  
  

Technical Notes

• Title: A straightforward method for determining the pulse widths of sinusoidal PWM waveforms
  Author: M.T. Escoto, Jr.
  Abstract: 

  A simple, speedy and straightforward method is given for calculating the widths of a sinusoidally modulated pulse train.  The method employs the fact that a pulse has its average value proportional to its duty ratio.  By setting this duty ratio proportional to the height of a sine wave, the width is thereby easily calculated.  The method is shown for the generation of a single phase sinusoidal PWM.

  
  
• Title: An energy-saving idea for airconditioning systems in phased construction projects
  Author: A.B. Santos
  Abstract: 

  In multiple-building projects wherein the buildings are constructed one by one, the number of standby chillers for the whole complex will be more than necessary if each buildings air conditioning system is exclusive to itself.  However, if the refrigeration plants of these buildings are interconnected, the number of standby units will be reduced compared to the conventional method of designing refrigeration plants for airconditioning in phased construction projects.  This paper discusses the design concept undertaken by the DCCD Engineering Corporation for the Ayala Center in Makati.

   

  
  
• Title: Design-storm unit-hydrograph computer program
  Author: P.T. Templo, Jr.
  Abstract: 

  The estimate of the design flood is one of the governing inputs for the selection and sizing of many infrastructures.  While the design storm unit hydrograph approach is one of the most reliable method for the estimate of flood magnitude, its computation if done manually, is too tedious.  A computer program should make the method usable to a number of practicing hydrologists.

  
  
• Title: EDI: Technology for paperless transaction
  Author:  E.F. Abaya
  Abstract: 

  “Electronic Data Interchange” or EDI refers to the electronic transmission of commercial documents in a standard format.  The standardized characteristics of the electronic transmission will allow a business transaction to be conducted in a purely automated manner.  This tutorial paper will discuss the technical concepts of EDI using as an example the UN EDIFACT standard.

  
  
• Title: Matrix Operation on Micros (MOM)
  Author: Dr. Salvador F. Reyes
  
• Title: New challenges in building fire safety
  Author: R.G. Roque
  Abstract: 

  As buildings grow higher and their uses become more complex, and as plastic-based combustible loadings increase, building fires become a complex problem.  Dramatic progress has been made in fire protection engineering.  Unfortunately, our local building and fire codes have lagged behind the current technology.  Direct code application may not be the best and most economical solution.  Alternative solutions must be equal to or better than the code requirements.  Building fire safety is not accomplished only by installing a sprinkler system, but must also include an egress system that affords an acceptable level of life safety, an alarm and detection system that is reliable, an effective smoke control system, an economical fire protection covering for structural members, and a strategy for maximizing the capabilities and resources of the fire department.  Integration of the various fire protection features is the new challenge in building fire safety.

  
  
• Title: Philippine Country Report: Metalforming, and metal casting sectors
  Author: A.R. Gopez
  Abstract: 

  This paper gives a country report on the status, technology, manpower, and development plans of the welding, metalforming and metal casting sectors of the Metals and Engineering Industry.

  Welding is used predominantly by about 1400 small-scale iron works fabrication shops, 35 vehicle chassis and body makers and 13 pipe and tubemakers with an existing aggregate capacity of 300,000 mt. In metalforming, there are 25 bar-rolling facilities, 8 wire and rod rolling facilities and 6 structural section rolling facilities with an aggregate of 938,400 MT.  There are sixty firms utilizing wire forming techniques to manufacture wire products, while only five firms offer mechanized steel forging.  Smithery or hand forging is widely practiced in at least 6 regions of the country.  Extrusion technology is used by five firms, while sheet metalforming is widespread in the urban communities.  The country has 221 metalcasting plants but only 153 are operating.

  Equipment inventory in welding showed that about 60% are metal arc welding machines while 21% are oxy-acetylene welding sets.  In metalforming, industry sources have estimated that 60% of the facilities use second hand equipment at least 20 years old.  The degree of mechanization of metalcasting plants is low, with only 24% of the parts being partially mechanized.

  Manpower needs of the three sectors, according to a study by the National Manpower and Youth Council, are substantial, with about 1800 additional welders, 1700 additional mill workers, 1000 sheet metal workers needed per year up to 1993.  No figures are cited for the metalcasting sector.

  
  

Research Briefs

• Title: A lahar database
  Author: NHRC
  
• Title: Calibration of the SYSOPS computer model
  Author: P.P.M. Castro
  
• Title: I.E./O.R. Research and development opportunities in distribution and transportation
  Author: O.G. Villoria, Jr.
  
• Title: Industry needs in quality improvement
  Author: R.T. Domingo
  
• Title: Industry-Academe research linkage
  Author: F.T. Berba, Jr. and A.J.R. Gopez
  
• Title: R & D in information systems and technology
  Author: J.G. del Rosario
  
• Title: Siltation problems in the Calaca harbor
  Author: E.G. Gregorio
  
• Title: Tapping the operations research potentials
  Author: E.A. del Rosario
  

PEJ Vol. XI, No. 2 December 1990

• Title: A tutorial for electronic circuit design using spice
  Author: M.T. Escoto, Jr.
  Abstract: 

  A general approach to electronic circuit design is outlined.  The iterative design path is identified to cite, particularly, the usefulness and the advantages of circuit simulation.  Finally, a design example for a high voltage DC power supply is developed.  Applying Spice demonstrates the usefulness of circuit simulation in the iterative process of circuit design before the circuit is built and after one thinks the design is complete.

  
  
• Title: Development of equivalent circuit models for nonlinear resistors
  Author: R.G. Solis
  Abstract: 

  The modeling of non-linear devices confront both users and developers of computer-aided design programs.  This paper shows how large-signal models for voltage and current controlled resistors can be developed based on the piece-wise linear characteristics of the device.  For both voltage controlled and current controlled non-linear resistors, two models are developed.  One model is Foster-like in the sense that the sub-circuits are connected either in series or parallel to form the model.  The other model is Cauer-like in the sense that the topology is of ladder type.  Methods for developing the models are presented.

  
  
• Title: Digital signal processing applications in monophonic music analysis
  Author: R.C.L. Guevara
  Abstract: 

  This paper presents an approach to monophonic music analysis using guided, continuous, overlapped fast Fourier transformation.  This method is based on the physiological activity of the ear which can be modeled as a bank of contiguous bandpass filters.  The analysis involves pitch detection, determination of note duration and identification of instrument limited to flute, clarinet and trumpet. 

  
  
• Title: Most powerful and locally optimum detection in additive noise
  Author: E.F. Abaya
  Abstract: 

  A fundamental problem in many types of digital communication receivers is that of discriminating between the presence or absence of a signal of known form mixed with additive noise.  This paper considers the structure of two detectors designed for different optimality criteria respectively known as the most powerful (or Neyman-Pearson) detector and the locally optimum detector.  It is shown that an affine relation between the nonlinearities of the two detectors is a necessary and sufficient condition for the two detectors to reduce to identical forms.  This property is used to search for noise densities which have common detector structures. 

  
  
• Title: The role of the academe in technology application and promotion
  Author: F.L. Viray
  Abstract: 

  The paper defines three (3) parallel streams of human activity and their interrelations, namely, Science, Technology and Utilization.  Based on these definitions, the role of the academe in technology application and promotion is described.

  
  

PEJ Vol. XII, No. 1 June 1991

• Title: A groundwater database for Metro Manila and Laguna Lake Basin
  Author: Dr. Leonardo Q. Liongson
  Abstract: 

  A groundwater database for Metro Manila and Laguna Lake Basin has been initiated in 1990 together with an on-going three-year research project on the conjunctive management and modeling of surface water and groundwater resources in the region. Through a formally organized multi-agency linkage and cooperation, a substantial collection of all agency-sourced secondary groundwater and other related data (circa: 1950-present) has been achieved after the first year.  The regional database so far consists of 201 technical reports and publications, 234 maps of various types, lithology and other well data for 5911 wells, groundwater level data for 57 observation wells, water quality data for 35 sampling stations, streamflow and lake stage data for 29 surface water stations, climatic data for 17 climate stations, and seismic-reflection and georesistivity data for aquifer geometry.  Aside from its immediate use in the on-going project, the database has other important long-term applications.  The database collection and functions are being continually augmented and enhanced in order to realize their long-term utility and potential as a source of vital groundwater information for the general user, as management tool for water resources planners and technologists and as generator of research information and studies to be conducted by faculty, researchers, students, and practicing engineers.

  
  
• Title: Development of data, models and techniques to determine optimal reliability level of electric power supply for the Philippines
  Author: Dr. F.L. Viray, R. R. del undo, et. al.
  Abstract: 

  This study develops models and techniques to determine optimal reliability level of electric power supply for the Philippines using data from NPC Luzon grid.  A survey of outage cost incurred by industrial firms in Metro Manila and suburbs from January to June 1990 was used to develop the outage cost model.  The cost of increasing reliability and the cost of having an unreliable one, from the point of view of the national economy are combined to determine the optimal level which is the point where the total cost is minimum.

  
  
• Title: Diversion requirement estimation for paddy rice irrigation systems
  Author: M.R. de Vera
  Abstract: 

  A methodology for estimating the diversion requirement of lowland rice is presented using a cropping pattern based on rainfall distribution and dependable streamflow in the Bicol River basin.  The case study involves some 8,000 hectares to be irrigated.  Results of the study showed decadal irrigation diversion requirement varying from 0.07 to 1.76 liters/second/ha depending upon effective rainfall and crop growth stage.  These figures are useful for system design and operation including water management.

  
  
• Title: Operation and applications of rice hull gasifier-combustors
  Author: : F.D. Vinluan, Jr. A. Santos, et. al.
  Abstract: 

  The gasifier-combustors operate on the principle of the open core, batch type gasifier.  The gas generated in the reactor, which has a heating value of 3,900-4,000 kJ/SCM is ignited in the gas exit or piped to a thermal equipment.  Two (2) reactors with internal diameters 45.72 cm (drum-size) and a large (square) unit with 105 cm. x 105 cm. in cross section were used.  The drum-size gasifier-combustor were used to fire clay bricks in a small wood-fired kiln. Four (4) drum-size units were also used to fire bricks in a shuttle kiln.  The result show that a temperature of 750-850oC within the kiln was attained in 8-hour firing period.  The laboratory tests on the fired products revealed that their properties are within set standards.

  Initial tests on the use of the drum size units in a food drier (indirect drying) and in a grain drier (direct) show that the gasifier-combustor can maintain the required temperature within the drying chamber or plenum.  The economic projections show that it is economically feasible to adopt the gasifier combustor for food and grain drying.  Other agrowastes such as coconut husks, corn cobs and coffee hulls were also tested successfully as fuels in the drum-size units.

  The  large unit is capable of delivering 1 million kJ/hr will be attached to a 6 cu. M. wood-fired kiln for brickfiring.  As envisioned, this type of equipment will be used as heat source of a boiler for power generation and process heat.

  
  

PEJ Vol. XII, No. 2 December 1991

• Title: A background on system identification in structural engineering using Kalman filter
  Author: A.W.C. Oreta
  Abstract: 

  System identification is an important step towards the aim of evaluating the existing condition, assessing the degree of damage and deterioration and predicting the response of structures.  In this regard, this paper aims to provide the structural engineer a background on the application of system identification in the field of structural engineering using Kalman filter techniques.  The basic concepts in system identification and parameter estimation are described and the linear discrete Kalman filter algorithm used to carry out the system identification is summarized.  To illustrate the system identification by Kalman filter, a single degree-of-freedom system was analyzed.  A survey of researches related to this field is also presented.

  
  
• Title: BBBTUTOR: Tulong-Pangturo sa Statika sa pamamagitan ng computer
  Author: E.S. Pacheco
  Abstract: 

  Isang programa sa computer na tulong pangturo sa paggawa ng banghay ng bukod na bagay (BBB) o’free body diagram ang ginawa upang makatulong sa mga estudyante sa Statika na nahihirapang intindihin ang konseptong ito.  Ang programa ay pinatatakbo sa pamamagitan ng mga menu at hindit kailangan ng gagamit nito ang kaalaman sa pagprograma ng computer. Gagabayan ng programa ang estudyante sa bawat hakbang ng paggawa ng BBB ng ibat-ibang estruktura at may komentaryo at paliwanag na lilitaw sa screen kapag hindi tama ang ibinigay na sagot sa aing mang katanungan.  Pinapayagan ng may-akda na kopyahin ng sino mang interesado dito ang nag-iisang diskette na naglalaman ng programa.

  
  
• Title: Channel utilization of a half-duplex ARQ protocol for packet radio channels
  Author: E.F. Abaya
  Abstract: 

  ARQ is a common error control method for terrestrial data transmission.  The different types of ARQ are reviewed, and channel utilization characteristics are summarized.  A half-duplex go-back-N ARQ method is presented as a model for the AX.25 ARQ protocol used in packet radio, and an equation for channel utilization is derived and analyzed.

  
  

PEJ Vol. XIII, No. 1 June 1992

• Title: Automatic monitoring of water pollution with emphasis on biological monitors
  Author: G.L. Peralta & G.S. Puga
  Abstract: 

  Recent developments in the field of automated monitoring systems include sate-of-the art instrumentation which makes full use of existing computer technology and automation processes in environmental monitoring.  This paper will describe the various technologies in automatic monitoring of water pollution, ranging from biological to physico-chemical methods with stress on biological monitors as they are fast gaining attention from researchers worldwide, offering great promise in the future especially in developing countries.

  
  
• Title: Biomass equipment suppliers and technological potential in selected Philippine agro-based industries
  Author: A.R. Dalusung, III
  Abstract: 

  This paper gives an overview of the technical and financial viability of using agricultural residues to generate heat and/or electricity.  The government’s policy toward cogeneration and private sector power generation is discussed.  The paper identifies the key factors that boost the potential of cogeneration, particularly when available biomass residues such as bagasse, rice husk and coconut shells/husks are used.  It also looks at the technical, economic/financial and institutional issues that confront projects of this nature.  The paper discusses the status of domestic manufacturing capability and the end-user interest in cogeneration projects. Finally, it gives a profile of three sectors (namely sugar, rice and coconut) with potential for the application of cogeneration projects using biomass residues.

  
  
• Title: Energy demand and fuel substitution model for urban domestic sector (For Electricity Planning): The case of Nepal
  Author: K.B. Rokaya
  Abstract: 

  The Domestic Sector is the major consumer of energy in most developing countries which is also true for many developed countries.  Household cooking, which is a very vital and essential end-use activity in domestic sector, consumes a major portion of the total energy consumed in this sector.  The potential for fuel substitution is also very high for household cooking energy use in domestic sector, specially in urban areas where commercial energy has usually a major share in the total energy consumption.

  In this study, an analytical model has been developed for energy demand projections and fuel substitution studies for urban domestic sector.  The model can be used to update the electric load forecast and consequently the electricity generation expansion plan.

  The model has been applied to make energy demand projections and fuel substitution studies for urban household cooking in Nepal.

  The results reveal that the potential for substituting kerosene oil with electricity in urban cooking is very high in Nepal.  The change in the electric load forecast for Integrated Nepal power System due to kerosene oil substitution is very significant.  The availability of vast hydropower potential makes this substitution possible.

  The total cost of supplying energy for urban household cooking in Nepal has been calculated for the different scenarios considered.  The economic viability of substitution of imported kerosene oil with indigenous hydroelectricity depends on the price of kerosene oil vis-à-vis the cost of developing hydroelectricity.

  
  
• Title: Immobilization technique for toxic sludge
  Author: G.L. Peralta, F.C. Ballesteros, Jr. and M.L. Cepeda
  Abstract: 

  High concentrations of heavy metals such as Ag, As, Cd, Cr, Hg and Pb in a sludge generated from a cooling tower can not be directly disposed of in a sanitary landfill without risking groundwater contamination.  Preliminary studies on the sludge show that the heavy metal concentrations are beyond the standards set by the USEPA.  This necessitates the treatment of the sludge prior to final disposal.

  The solidification technique was employed to immobilize the contaminants to a degree where it no longer poses an environmental hazard.  The technique utilized silica-rich materials such as portland cement and rice hull ash as immobilizing agents.

  Simulation studies of the behavior of the treated sludge during long-term storage showed significant reduction in heavy metal mobility to within the standards.  X-ray diffraction (XRD) analysis of the cementitious product point to physical entrapment of the heavy metals within the ettringite/silicate matrix as the main immobilizing mechanism.

  
  
• Title: Kinetic properties of separated solid-liquid fractions of blended swine waste slurry
  Author: J.A. F. Bedaño & W.I. Jose
  Abstract: 

  The kinetic properties ultimate methane yield (bo) and substrate inhibition coefficient (K) of separated solid-liquid fractions of blended surface-scraped swine waste were evaluated from data on batch digestion and semicontinuous high-rate digestion.

  Results showed that the solid fraction had a lower Bo (0.373 li CH4/gm VS added) than the liquid fraction (0.498 li CH4/gm VS added) due to its higher concentration of refractory materials.

  K was evaluated using Chen & Hashimoto’s model for continuous well-mixed anaerobic systems at steady-state.  The relationship between influent substrate concentration (So) and K was found to be exponential.  Empirical equations derived at different combinations of organic loading rate (OLR), Hydraulic retention time (HRT) and temperature are as follows:

  Solid Fraction:

  K = 0.429 + 0.00177 exp (0.187 So), r2 = 0.997

  Liquid Fraction:

  K = 0.798 + 9.43x10-8 exp (1.808 So), r2 = 0.863

  The threshold substrate concentration where inhibition might start was approximately 30 gm VS/li for the solid fraction and 8 gm VS/li for the liquid fraction.

  
  

PEJ Vol. XIII, No. 2 December 1992

• Title: Special Issue: Abstracts of Theses and Dissertations College of Engineering, U.P. Diliman 1981-1992
  Author: 
  Abstract: 

  -   Chemical Engineering

  -   Civil Engineering

  -   Electrical Engineering

  -   Energy Engineering

  -   Environmental Engineering

  -   Industrial Engineering

  -   Mechanical Engineering

  -   Metallurgical & Mining Engineering

  -   Nuclear Engineering

  
  

PEJ Vol. XIV, No. 1 June1993

• Title:  Pollution sources and water quality assessment in Metro Manila and Laguna Lake Basins
  Author: G.L. Peralta, R.S. Soriano, and C.Q. Dizon
  Abstract: 

  As one of the major tasks in the IDRC-funded project “Water Resources Management Model for Metro Manila” the water quality of both surface and groundwater resources in the Metro Manila and Laguna Lake Basins was assessed based on available data and information.  Refuse dumpsites, industries, and underground storage tanks as possible pollution sources were identified and map-located.  Groundwater quality data provided by the Metropolitan Manila Waterworks and Sewerage System (MWSS) and the Department of Health (DOH) was evaluated and compared with the National Standards for Drinking Water.  Groundwater quality maps for Metro Manila were generated for the following parameters:  pH, chloride, turbidity, total dissolved solids, iron, and hardness.  A groundwater vulnerability map was developed for Metro Manila based on mappable hydrogeological parameters.  Report findings on the water quality status of the Laguna Lake and Metro Manila Rivers is also presented.

  
  
• Title: A conjunctive water management model for Metro Manila and Laguna Lake Basins
  Author: L.Q. Liongson, D.S. Rojas, et. al.
  Abstract: 

   This paper presents the objectives and accomplishments of the water resources management modeling project undertaken by NHRC during the period 1990-1993.  Presented in particular are the features of the Manila Model or CUWARM (Conjunctive-Use Water Resources Management Model), consisting of a coupled groundwater hydraulic-subsidence model, and including daily, monthly, and annual surface-water models.  Discussed in detail are the equations and solutions of the groundwater model, the pre-calibration runs for model tests, and the computational and input-output features of the developed Manila Model.  The results of the calibration runs for Metro Manila are presented.  Conclusions and recommendations on both modeling and management aspects are given.

  
  
• Title: Evaluating the hydraulic capacity of existing hydropower plants
  Author: R.C. Villa
  Abstract: 

  Expanding the generating capacity of existing hydropower plants requires an increase in the hydraulic capacity of the conveyance system.  Hydraulic analysis must be undertaken not only to establish the hydraulic capacity of the existing system but also to serve as aid in the formulation of schemes to increase the hydraulic capacity.  Guidelines for the conduct of hydraulic analysis for small hydropower plants are discussed.  Major factors which have to be considered are also outlined.

  
  
• Title: Port of Pulupandan: Tide Model
  Author: E.G. Gregorio
  Abstract: 

  This paper describes the physical model study of the Port of Pulupandan siltation problem.  A fixed distorted model (1:250 horizontal, 1:50 vertical) reproduces the prototype hydrography.  The model uses the Froude criteria but simulation is limited to the tidal variation only.  The study is focused on identification and reduction of eddy zones.

  Four basic layouts and its modifications are tested.  The results of the model investigation lead into the selection of Alternative No. 3 layout that produces promising flow pattern and smaller eddy zones.  The selected layout not only exhibits streamlined flow but also entails minimum disturbance to the existing facilities hence less capital investment is involved.

  
  
• Title: Software development for fluid-flow visualization using computer graphics and animation techniques
  Author: L.Q. Liongson
  Abstract: 

  This paper presents the principal results of a two-year software development project for the visualization of fluid motion using computer graphics and animation techniques.

  Twenty-five (25) visualization programs have been developed for potential flows, viscous flows, flows with heat and mass transfer, geostrophic flows, and open-channel flows. Single-page and double-page animation, and palette rotation (neon-light effect), featuring on the monitor screen the display of both text and graphics with color, animation, and sound, are the essential techniques utilized. Classical tools in engineering mathematics were numerically applied and implemented, such as complex variable theory conformal mapping, both analytical and numerical solutions of ordinary and partial differential equations, and stochastic or random-walk simulation of the diffusion process.

  The applied techniques (computer graphics, animation, analytical and numerical methods in engineering mathematics) exhibited varying degrees of performance in terms of a meaningful perception of fluid motion, depending on appropriateness of the application to certain types of flows and on the nature and amount of detail present in the images. With the added features of a simple and guided input menu, a facility for instant replay, and a real-time mode of computation and display, the programs serve as interactive teaching tools in fluid mechanics.

  
  
• Title: The NHRC water database for planning and research
  Author: R.S. Soriano, D.S. Rojas, and C.Q. Dizon
  Abstract: 

   The NHRC Water Database is a collection of hydrologic, hydrogeologic and geologic data, and other water-related data and information on the Metro-Manila and the Laguna Lake Basins.  Gathered through the course of the three-year IRDC-funded research study “Water Resources Management Model for Metro Manila” undertaken by the NHRC, the data and information were contributed by the MWSS, MB, EMB, LLDA, UP NIGS, UP University Library, LWUA, NAMRIA, PAGASA, BSWM, DPWH, DOH, and OEA.

  The processing and analysis of the data and information were primarily aimed at obtaining the inputs to the Conjunctive-Use Water Resources Management Model or CUWARM.  Digitized maps (e.g. soil type, land cover, geology, drainage basin definitions), contour plots (e.g. topography, geologic basement, mean annual rainfall, piezometric levels), statistical parameters and plots of time series data (e.g. rainfall, streamflow, groundwater level), and well lithologic logs are some of the computer-generated outputs from the database.  Through the database, water related information can readily be accessed and processed to facilitate various research or planning activities by NHRC and other interested parties or agencies.

  
  
• Title: Two decades of NHRC research
  Author: A.A. Alejandrino
  Abstract: 

  The report describes how hydraulic research in the Philippines was institutionalized and made viable for the past 20 years.  It considers the unique organization of the National Hydraulic Research Center, the research areas, the training aspects, the viability of NHRC, and a vision for hydraulic research.

  
  
• Title: Water balance studies using a Geographic Information Systems (GIS) approach
  Author: C.Q. Dizon
  Abstract: 

  A surface water balance model for Ni Khu Hu and Tatha watersheds was developed by applying remote sensing and water balance modelling using a geographic information system.  The study area is located at Thong Pha Phoom district, Kanchanburi province, western part of Thailand.  The annual climatic data of the study area was used to determine the available water from the water balance equations.  The LANDSAT TM image of the area was classified by image processing to produce the land use map.  GIS modeling produced GIS maps of rainfall, evapotranspiration, land use, soil, slope, excess moisture and surface runoff.

  
  

PEJ Vol. XIV, No. 2 December 1993

• Title: Beams
  Author: E.S. Pacheco
  Abstract: 

  An interactive computer program was developed for the universal solution of the different equation of the elastic curve which was derived by the author in an earlier paper.  This program determines the reactions at the supports and constructs the shear and bending moment diagrams of statically determinate as well as statically indeterminate beams. It computes the maximum bending and transverse shear stresses for eight beam cross-sections.  It also makes a sketch of the elastic curve and determines the deflection at selected points as well as the maximum deflection.  The beam supports may be at the same or at different levels.

  
  
• Title: Conical grate rice husk combustor for grain drying
  Author: P.H. Hien, et. al.
  Abstract: 

  An experimental conical grate rice husk furnace was designed, fabricated, and tested in Los Banos at the agricultural Engineering Division of the International Rice Research Institute. Experiments were performed with the furnace under suction from an axial-flow fan. Drying air efficiency of the furnace was found to lie in the range 60 – 80%. At a rice husk burning rate of 32 – 38 kg/hr, the furnace was compatible with a flat-bed dryer demand of 4-6 tons/batch for 6 – 8 hr continuous operation. The furnace has a simple cable-type transmission which provides synchronized fuel feeding and ash discharge, and is lightweight relative to its heat load.

  The charred ash from the furnace contained from 6 to 15% unburnt carbon and was amorphous, as examined by the X-ray diffraction method.

  Problems in continuous operation of the gasifier-combustor were identified, the major constraint being rice husk feeding flow at high temperature.

  A rice husk gasification equilibrium (RHGE) model was developed to predict gasifier performance. The model used a reactivity factor Rf to account for biomass reactivity relative to that of graphite, and took account of the ash content and the % Unburnt carbon of rice husk in the mass and heat balance equation. Comparison between RHGE model-generated data and published experimental data showed that the model adequately predicted gasifier performance.

  
  
• Title: Engineering manpower and training needs of the various industries vis-à-vis curricular/training programs in selected engineering schools
  Author: F.L. Viray and D.S. dela Cruz
  Abstract: 

  The study is based on the result of a survey conducted among establishments in mining and quarrying, manufacturing, electricity, gas and water; construction; tansport, storage and communications and banking located in Regions 4,7,10,11 and NCR.  The study shows that: (a) engineering graduates are mostly employed either in management/administrative or are doing low level technologies’ work and only  a small fraction of them are employed in work that requires engineering skills such as design and research and development; (b) engineering education is perceived to be either adequate or inadequate depending on whether the operation of the company is specialized or not; (c) most companies provide for the training needs of their newly-hired engineering graduate especially in management or in specialized technical skills, through on-the-job or in-house trainings; and (d) companies still deem that the following must be effected to uplift engineering education: more time for on-the-job trainings, improve facilities, improve curriculum and improve teaching faculty.

  
  
• Title: Household electricity consumption in the Philippines
  Author: A.R. Dalusung III, and A.S. Lagman
  Abstract: 

  Past efforts on energy conservation programs have been directed largely at industrial and commercial establishments, which have traditionally been large energy users.  The growing residential power demand, estimated at 6,336 GWh and accounting for 29.7% of 1992 power consumption, also opens prospects for energy conservation.

  The study assesses the characteristics of household electricity demand in Metro manila and identifies areas where demand management schemes can have the greatest impact on the power supply base.  The study benefitted largely from the 1989 household energy consumption survey conducted by the then Office of Energy Affairs under the World Bank-Energy Sector Management Assistance Program.

  Review of the size and structure of household electricity demand indicates large potential energy savings from the use of more efficient lighting, airconditioning and refrigeration.  The cost of conserved energy from the use of efficient energy-using devices is far less than the cost of installing additional power capacity.  An intensified and sustained nationwide energy conservation also addresses the growing environmental issue while lowering energy imports and thus improving the country’s balance of payments position.

  The study emphasizes that the gains achieved from earlier efforts can only be sustained and advanced with the synchronization of various efforts from both the legislative and executive branches of government.  The support of the private sector, covering the power utilities, media, non-government organizations, and consumers, is also imperative.  Among various recommendations, the restructuring of power tariffs is deemed to be the single most effective factor in promoting energy conservation.  By providing the right pricing signals, consumers will be compelled to orient their purchasing decisions towards energy-efficient appliances and technologies and to alter their power consumption behavior.

  
  
• Title: MMDF Electronic Mail
  Author: E.F. Abaya
  Abstract: 

   E-mail is a system for sending electronic messages through a computer network.  This paper discusses the internal processes of a mail system in a Unix and TCP/IP environment, focusing on the Multi-channel Memorandum Distribution Facility (MMDF).

  
  
• Title: Optimization of fluidized bed combustion of Semirara coal
  Author: J.C. Elauria and I.E. Cruz
  Abstract: 

  A study was conducted to determine the suitability of local coal as fuel in fluidized bed combustor (FBC) and to establish the optimum operating conditions of the FBC unit.  A 6-inch diameter reactor with Pampanga river sand (mean particle size of 1.139 micrometer) as inert bed material was used in the conduct of the experiment.  Combustion tests were run at air flow rates of 180 and 260 L/min, A/F ratios of 7.6 and 11.0 kg of dry air per kg of fuel, bed depths of 6 and 9 inches and bed temperatures of 820 and 910oC.  Coal sizes of -1/16 + 1/32, -1/8 + 1/16, and -1/4 + 1/16 inch were evaluated based on their fluidization characteristics prior to experimentation.

  Coal size of -1/16 + 1/32 inch registered a minimum fluidizing velocity close to that of the bed material but coal size of -1/16 + 40 mesh is recommended due to higher recovery during size reduction.  Combustion efficiency ranged from 52 to 98 percent, while heat output rates ranged from 1,438 to 3,295 Kcal/kg of fuel equivalent to 27.6 and 63.3 percent thermal efficiencies.  Combustion and thermal efficiencies are directly affected by air flow, A/F ratio and bed depth.  Temperature is also positively related to thermal efficiency.  The optimum performance of the FBC unit was found to be at bed temperature range from 902 to 910oC, A/F ratio of 11.0 and 11.6, air flow of 260 to 285 L/min and bed depth of 9.0 to 11.1 inches.  The study as a whole showed that low quality coal (low heating value and high ash content) such as Semirara is a viable fuel in fluidized bed combustor.

  
  
• Title: Perspective on the training and education of world-class engineers
  Author: AJ.R. Gopez
  Abstract: 

  World class manufacturing implies a philosophy of manufacturing excellence. It is strongly dependent on having properly trained engineers. It is also strongly linked to the ability of a company to compete in the global market. Using Michael E. Porter’s “The Competitive Advantage of nations” as the framework together with the increasingly strict requirements of the semiconductor industry as a benchmark, this paper presents viewpoints on the training of engineers for global competitiveness. Experiences drawn from the UP and DLSU Manufacturing Linkage Programs were also used for guidance.

  The critical items required for engineers to be competitive in a world class environment include: the ability to solve problems by proceeding from the basics and the ability to consider the human aspects as part of a technical solution. Additional technical aspects would be based on Total Quality Management (TQM), together with additional training on statistical concepts applied to process improvement, manufacturing and design of experiments. Finally, the training must emphasize innovativeness and even creativity.

  
  

PEJ Vol. XV, No. 1 June 1994

• Title: An operation research and systems analysis study of weighing scales used for growth surveillance
  Author: N.O. Raneses, F.G. Menegdeg and A.C. Ramos
  Abstract: 

  Weight is the accepted indicator of growth in the growth monitoring system in the Philippines.  The right choice and correct use of the appropriate weighing instrument or scale is of paramount importance for procuring accurate weight during weight surveillance (Operation Timbang).  This operations research and systems study evaluates the different weighing scales used in the field, examines the different factors causing inaccuracies in weighing, investigates the feasibility of locally manufacturing the required weighing scales, and scrutinizes the calibration, maintenance and procedure needs of the recommended weighing scales, and scrutinizes the calibration, maintenance and procedure needs of the recommended weighing scales.  Seventy-eight (40 Rural health Units and 38 Barangay Health Stations) health stations in Marikina, Quezon City, Pangasinan and Cavite were surveyed.  The bar scale, the Salter spring-type weighing scale, the adult clinical scale and the bathroom scale were found to be the most commonly used weighing instruments.  Calibration, maintenance and proper use were generally observed to be wanting and inadequate.

  The study recommends the phase out of the bathroom scale: the use of the Salter spring type: the infant beam scale and the bar scale when weighing in the field; and the use of adult clinical scale or beam type clinical scale at health stations.  It further recommends the standardized regular calibration and maintenance procedure for all scales used in growth monitoring.  All procedures are recommended to be in simple instructional form.  For calibration, the use of standard test weights is recommended.  The study finally recommends a modified weighing scale and crib design and the establishment of a regular replacement cycle for these weighing instruments.  The local manufacture of weighing scale was found to be feasible.

  
  
• Title: Expert systems in production: An exploratory study
  Author: V.D. Ong and N.O. Raneses
  Abstract: 

  The paper concerns itself with the applications of a branch of artificial intelligence called “expert systems”.  It describes some expert systems’ industrial engineering applications according to category, model or prototype name, developer, problem domain, decision output, development tools, and methodology or assessment. 

  The study focuses on the wide-ranging applications of expert systems in production especially in the areas of materials handling, process specification and planning, production planning and scheduling, simulation and data analysis, operations analysis, facility and workplace design, database management, equipment diagnosis, robotic, and quality assurance.  A survey of 100 expert systems production applications reveals its main uses as follows: planning (23%), diagnosis (17%), design (14%), and control (14%).  The paper finally ends with the prospects and projection of research and development on expert systems in the field of industrial engineering in the Philippines.

  
  
• Title: Group technology in systems integration
  Author: N.O. Raneses
  Abstract: 

   Systems integration (SI) requires that components must be thoroughly analyzed, simplified, standardized and optimized over its lifespan to achieve true integration. Group technology (GT) provides a rational framework for integrating systems.  GT is a disciplined approach of grouping parts, process, equipment, tools, people, information, energy or subsystems based on similarities and optimizing their efficiency and effectiveness over time.  It involves attribute identification and family formation, classification and coding, simplification, standardization and optimization.  Family formation, classification and coding are the cornerstones of group technology.  We have established that GT is a science-based concept which has many potential applications for simplifying, standardizing and optimizing complex systems.  Design guidelines on how to effectively carry out GT are given.  Specific research and development trajectories are suggested.

  
  
• Title: Measuring process capability
  Author: N.O. Raneses
  Abstract: 

  Process capability indices are succinct unitless statistical metric which measures the amount of common cause variation present in a process.  They indicate the ability of the process to meet engineering specifications or whether process centering poses a problem.  First and second generation indices: Cp, CpL, Cpu, Cpk, k, Cpm and Pearson process capability indices are presented, examined and compared.  Single and confidence interval estimates of these indices are described.  Finally, applications, drawbacks and uses of these indices are discussed.

  
  
• Title: The professional and practice of industrial engineering
  Author: N.O. Raneses
  

PEJ Vol. XV, No. 2 December 1994

• Title:  Engine cycle analysis using an ideal gas with constant specific heats as a working fluid
  Author: E.N. Quiros
  Abstract: 

  This work presents the results of computer modelling of the basic and idealized engine cycles assuming the working fluid to be an ideal gas with constant specific heats.  The various processes that constitute the engine cycles are assumed to be ideal.  A thermodynamic analysis of the engine cycles is performed to calculate performance parameters.  Parametric studies using the computer model was conducted to determine desired engine design and operating conditions.

  
  
• Title:  Liquefaction-induced large ground displacements: Part 2 – prediction by energy model
  Author: R.P. Orense
  Abstract: 

   This paper deals with the modeling of liquefaction-induced large permanent ground displacements.  Based on the information obtained from case studies and shaking tablets tests, a technique is developed to predict the ultimate ground displacements that will develop when the state of soil liquefaction is continued for a sufficiently long period of time.  The method is based on principle of minimum potential energy, and effect of earthquake motion is removed from the analysis. The distribution of the ground displacement is derived so that the potential energy of the ground would take minimum value.  Surface irregularity as well as ground heterogeneity are considered.  Both two-dimensional and three-dimensional models are developed.  Finally, the model is extended to include the temporal development of permanent displacement.  This is done by solving the equation of motion where the transient displacement is expressed as a fraction of the ultimate one.  An energy dissipation mechanism is incorporated stabilize the solution.  Analyses made on both laboratory and actual field cases show the validity of the model.  Thus, the technique can serve as an economical and practical tool to predict the potential seismic hazards to urban facilities and lifeline networks induced by the lateral flow of liquefied soil.

  
  
• Title:  Liquefaction-induced large ground displacements: Part 2 – prediction by energy model
  Author: R.P. Orense
  Abstract: 

  This paper deals with the modeling of liquefaction-induced large permanent ground displacements.  Based on the information obtained from case studies and shaking tablets tests, a technique is developed to predict the ultimate ground displacements that will develop when the state of soil liquefaction is continued for a sufficiently long period of time.  The method is based on principle of minimum potential energy, and effect of earthquake motion is removed from the analysis. The distribution of the ground displacement is derived so that the potential energy of the ground would take minimum value.  Surface irregularity as well as ground heterogeneity are considered.  Both two-dimensional and three-dimensional models are developed.  Finally, the model is extended to include the temporal development of permanent displacement.  This is done by solving the equation of motion where the transient displacement is expressed as a fraction of the ultimate one.  An energy dissipation mechanism is incorporated stabilize the solution.  Analyses made on both laboratory and actual field cases show the validity of the model.  Thus, the technique can serve as an economical and practical tool to predict the potential seismic hazards to urban facilities and lifeline networks induced by the lateral flow of liquefied soil.

  
  
• Title: An instrumented pulley for field measurements of torque and power
  Author: M.C. Pasikatan, F.A. Santos and G.R. Quick
  Abstract: 

  An instrumental pulley was developed to overcome field problems associated with the conventional method of torque and power measurement.  The prototype pulley was machined from mild steel, with spokes serving as strain beams.  Strain gages in bridge arrangement attached to the spokes sense the bending stress due to the torque and convert this into millivolt output.  Calibration results showed the torque-millivolt relationship was linear, hysterisis and error were less than 1% fs.

  For proper measurements, an additional tachometer with de voltage output is necessary.  With the tachometer, error in power measurement was +-1.03 W or 0.2% fs.  Field tests showed its advantages over the calibrated motor method such as, ease of installation, no weight addition relative to the original primeover, portability and safety.

  
  
• Title: Liquefaction-induced large ground displacements: Part 1 – Mechanism and general characteristics
  Author: R.P. Orense
  Abstract: 

  This paper deals with the nature and mechanism of liquefaction-induced large permanent ground displacements.  The study is carried out by first reviewing several historical earthquakes in which permanent ground displacements induced by soils liquefaction have been documented.  The information obtained is supplemented by the results of small and large scale shaking table tests, and the magnitude and pattern of ground movement are analyzed in relation to geomorphological and topographical factors.  The findings indicate that liquefied ground moves from higher elevation to lower elevation suggesting the effect of gravity, while large shear distortions occur in the liquefied soil.  Displacements are observed to be maximum at the top of the slope and minimum at the bottom of the slope.  The patterns of lateral displacements are strongly influenced by the topography of the area.  Seismic acceleration affects the permanent displacements of the liquefied soil only indirectly.  Based on these observations, it is suggested that the liquefied soil undergoing large displacements behaves like liquid.  Consequently, the idea can be used to predict the extent of permanent displacements of liquefied ground.

  
  

PEJ Vol. XVI, No. 1 June 1995

• Title: Analytical generation of stress-strain properties of coir fiber reinforced composites in axial compression
  Author: P.A. Jorillo,Jr., B.D. Verdejo, et. al.
  Abstract: 

  This paper examines the comprehensive stress-strain properties of concrete and mortar matrix reinforced with a natural cellulosic fiber i.e., coconut (coir) fiber. An extensive experimental program was carried out to investigate the inter-relationship of fiber reinforcing parameters such as fiber volume fraction, length or aspect ratio in combination with different grades of concrete or mortar matrices and the resulting stress and strain properties of the fiber-cement composite materials in axial compression.  In order to characterize the stress-strain curve of a fiber concrete/mortar, a fractional second degree polynomial model developed by Sargin (1971) and modified by Wang et al. (1978) was used in this study.  Findings showed that the analytical model can satisfactorily generate the complete stress-strain properties of a fiber composite material based solely on the knowledge of material properties of the composite constituents.

  
  
• Title: Continuous beams on elastic supports: an alternative equation
  Author: E.S. Pacheco
  Abstract: 

  The integrated equation of the elastic curve of an elastically supported continuous beam that is acted on by any number of concentrated forces, concentrated couples, and uniformly varying loads is obtained by using the Laplace transformation.  The support may consist of a Winkler foundation, and/or simple supports and/or cantilever supports which may be linearly elastic or rigid.

  
  
• Title: Design and development of a two post rotary-percussion drilling rig
  Author: P.C. Borlagdan
  Abstract: 

  A two-post Rotary Percussion drilling rig (AMDP Model 2 Drilling Rig) for shallow tubewell irrigation development was successfully developed at the Agricultural Mechanization Development Program, University of the Philippines at Los Baños.

  Consisting of a 5 horsepower horizontal shaft gasoline engine as the prime mover for rotary drilling, 4 horsepower direct coupled water pump for jetting, overhead platform mounted on two post system, a reduction gear box, hoist and cable system sub-assembly, sliding engine mount sub-assembly and basic strut supports; it is capable of drilling into various soil formations up to 100 feet and even deeper.

  This paper presents the design features and especial capabilities of said drilling rig.

  
  
• Title: Morphological and flexural properties of lightweight gypsum based fiber reinforced composite
  Author: P.A. Jorillo, Jr.
  Abstract: 

  This paper describes the results of the experimental investigations of the properties of lightweight gypsum based fiber reinforced composites.  Two general types of fiber reinforcement were examined, namely, polymer based fibers and natural fibers.  The study is essentially a developmental research with the objective of evaluating the properties of natural fibers in comparison with synthetic  fibers of the same density in a gypsum matrix.  A gypsum-cellulose pulp and a gypsum-shirasu balloon sand were used as lightweight gypsum matrices.  Experimental and analytical results on both standard specimens and full scale structural elements such as wall panel are presented.

  
  
• Title: Pozzolanic behavior of Mt. Pinatubo Ejecta under natural and accelerated curing condition
  Author: P.A. Jorillo,Jr. and B.D. Verdejo
  Abstract: 

  This paper describes the results of the study on the evaluation of the possolanic behavior of Mt. Pinatubo ejecta under natural and accelerated curing conditions.  The study is essentially a developmental research aimed in providing a comprehensive characterization of the volcanic ejecta in comparison with the local fly-ash.  Two types of accelerated curing were examined viz., high pressure steam curing and boiling-cooling method.  Various types of ejecta materials and percentage cement replacements were investigated to determine the optimum type and proportion in a cement based mortar matrix based on the criteria of strength and dimension stability.

  
  
• Title: Studies on the fusibility of coal ash
  Author: D.L. Pugal, A.B. Hererra, et. al
  Abstract: 

  A study, which aims to develop a technology for the preparation of a high quality adsorbent for Sox using coal ash control air pollution caused by coal-fired thermal power plants in the Philippines, is currently being jointly undertaken by ITDI and NHIRI.  During its first year of implementation, the physical, chemical and thermal characteristics of Philippine and Japanese coal ash samples were determined.  Results show that Philippine coal as samples are of the silicoaluminous type while that of the Japanese coal samples are of the aluminosiliceous type.  Three (3) common major elements, namely, quartz, mullite and hematite are found in all coal ash samples.  A correlation between the melting point and chemical composition of the coal ash samples shows that the coal ash samples having a low acid-base index resulted in high melting points.

  
  
• Title: Volcanic sand in asphalt concrete
  Author: D.S. Pagbilao and B.D. Verdejo
  Abstract: 

  Volcanic sand from three river sources, Abacan, Bacolor and Lubao, were investigated as an aggregate component of hot mix asphalt.  Laboratory test samples of asphalt mixtures containing these materials were evaluated according to their Marshall properties and their sensitivity to moisture damage.  The Marshall properties of mixtures containing volcanic sand as fine aggregate were found to be inadequate.  The use of volcanic sand as partial substitute to fine aggregate, on the other hand, do not adversely affect the Marshall properties of the mixtures significantly, however, their resistance to moisture damage were significantly reduced and the binder requirement were increased by 20%.

  
  

PEJ Vol. XVI, No. 2 December 1995

• Title: A review of oscillating screen-blower cleaners for grains
  Author: M.C. Pasikatan and G.R. Quick
  Abstract: 

  The literature concerned with grain or seed cleaners using blower and linearity oscillating screens, and related machines and mechanisms was reviewed.  Attempts in developing the theory and mechanics of cleaners was discussed.  Grain, straw and chaff aerodynamic and mechanical properties which affect separation were assessed.  The potential and limits of pure aerodynamic separation, effects of design, operating and material parameters on cleaning performance were critically examined.

  The available information may be limited, but sufficient to provide rough parameters for design under different operating conditions.  Researches show that to achieve good cleaning performance at high material capacity in wheat and paddy, air velocity of 7.2-9.2 m/s, air direction of 40-45o, height of drop of 70-102 mm, and hanger angles of 15-25o should be used.

  Attempts to relate cleaning performance with two or more influencing factors are rare in the literature.  Results derived with wheat and based on straw and shoe assembly to combines need to be validated for rice, rice threshers and cleaners.  Further studies that will lead to a universal cleaning equation and a good understanding of particle motion as influenced by several variables are needed.

  
  
• Title: Residue handling and soil disturbance of an inclined time furrow opener
  Author: P.C. Borlagdan, G.R. Quick and R.M. Lantin
  Abstract: 

  A vertical and an inclined tine-furrow opener, with 30o angle of inclination with respect to the vertical axis perpendicular to the toll bar, were compared and evaluated at different rake angles (60o, 75o, 90o and 105o) in terms of residue handling and soil disturbance.

  Three straw conditions were used namely: 1) standing rice stubbles without cut straw, 2) standing stubbles with wet cut straws, and 3) standing stubbles with dry cut straws.

  The thirty degree tine with 60o rake angle has the best residue handling capability but with lifting effect on soil.  Inclined tine with 90o rake angle has a neutral soil working effect.  The residue handling capability of the vertical and inclined tine decreases as the rake angle increases.  Soil lifting effect was apparent at rake angles less than 90o.  At rake angles greater than 90o there was soil compression.

  
  
• Title: Routing broadcast packets along a minimum diameter tree
  Author: E.F. Abaya
  Abstract: 

  In traditional computer networks, such as X.25 and TCP/IP networks, packets generally traverse the lowest cost route going from one source to one destination.  In recent years, new classes of computer and video services have emerged that transfer multiple copies of a packet from one source to many destinations (multicast or broadcast).

  This paper models the broadcast routing problem in a mesh computer network as a graph theory problem with a cost function that has to be minimized.  The paper proposes a new criterion for routing broadcast packets when each node in the network may be a source of broadcast packets directed to the other nodes.  Constraining broadcast packets to follow a single spanning tree, it is shown that a minimum diameter spanning tree is suitable choice for routing purposes.  A heuristic for generating a minimum diameter spanning tree is presented.

  
  
• Title: Selection framework for powerplant capacity mix
  Author: F.G. Manegdeg and M.G. Portal
  Abstract: 

   This paper illustrates multiattribute decision analysis in selecting powerplant capacity mix for the National Power Corporation that will meet the power demand of the Philippines by 2005.  The objective of this study is to provide a framework for the decision making analysis of the Systems Planning Department of national Power Corporation.  The preferences of two managers from the Systems Planning Department were elicited.

  The preferences and value judgments of the two decision makers on specified levels of production cost (capital cost, operation and maintenance costs, thermal energy needed), fatalities, environmental degradation (radioactive waste, sulfur dioxide, air particulate, nitrogen dioxide and hydrogen sulfide releases), socio-political acceptability and land use were determined.  There were ten (10) powerplant capacity mix alternatives generated.

  The preference model of decision maker 1 is multiplicative while decision maker 2 is multiplicative with additive submodels.  The alternatives that maximizes the use of combined cycle gas turbine and the use of fuel oil were ranked first and second, respectively, by the decision makers.

  
  
• Title: Stress stiffening and dynamic stress computation in flexible multibody dynamics: Formulation
  Author: R. Ledesma
  Abstract: 

  A formulation for the dynamics of flexible multibody systems is presented in this paper.  This formulation relies on the use of floating reference frames to describe the configuration of the multibody system.  Component flexibility is described in terms of the finite element deformation coordinates.  The equations of motion are derived through the generalized d’Alembert principle, and the resulting set of differential-algebraic equations are reduced to ordinary differential equations through the use of the augmented Lagrangian penalty method.  Modal reduction is utilized to reduce the dimension of the deformation coordinates.  Stiffening effect is included through the use of a stress stiffening matrix, which is computed efficiently as a linear combination of constant stress stiffness matrices with time-dependent scalar coefficients.  The same formulation is used to devise an efficient method for computing the dynamic stresses which include the effects of inertia due to gross motion and elastic deformation.

  
  

PEJ Vol. XVII, No. 1 June 1996

• Title: A DSP-based solution to the early identification of hearing impairment
  Author: V.P. C. Valentus
  Abstract: 

  This paper describes the development of a low cost DSP solution for the early identification of hearing impairment.  The desire is to develop a cost-effective, highly sensitive, and easily administered screening system for the evaluation of human hearing acuity.

  The proposed system is called EARTEST.  EARTEST is basically a DSP-based screening audiometer capable of performing pure tone air conduction testing.

  
  
• Title: A VHF crystal oscillator for satellite receiver
  Author: R.O. Olesco
  Abstract: 

  This paper will discuss the design of a crystal oscillator used as a local oscillation (LO) or satellite receivers in the VHF band.

  
  
• Title: An approximate design technique for microstrip parallel-coupled band-pass microwave filter
  Author: R.G.O. Ambrosio
  Abstract: 

  An approximate design technique is presented for parallel coupled bandpass filter in microstrip form.  Both computational and graphical forms together with simulation software are used to optimize the design.  Due to the use of several graphs and approximations, an average of 3% deviation from the computed to the final simulated design was noticed.

  
  
• Title: Fuzzy logic based decision system for the local control of signalized intersections
  Author: R.J. Ravago
  Abstract: 

  The objective of this study is to develop a fuzzy logic based system which will effectively control  a 4-lane intersection.  The controller is based on fuzzy logic and it has two inference engines which determine the actions in the intersection.  One fuzzy logic engine decides the phase length for a direction pair while the other decides the phase splits.  The system is adaptive in that it makes decisions based on currently available traffic data.  Testing of the system against a conventional traffic simulation have shown very favorable results.

  
  
• Title: Packet radio network for volcano monitoring: an implementation on Taal (Philippines)
  Author: R. Machenbaum
  Abstract: 

  This paper describes an implementation of a packet radio network on Taal volcano.  The network, based on amateur radio hardware and software allows the Philippine Institute of Volcanology and Seismology (PHILVOCS) to retrieve real time data from various instruments located on and around the volcano island.  The actual list of instruments includes 10 digital seismic stations, 3 tiltmeters, 2 radon sensors, 1 geochemical station (water temperature and conductivity) and an acoustic station.  The original features of the network are the use of only one radio frequency simplifying frequency allocation procedures and equipment management, redundancy allowing failures of nodes without loss of data, low power consumption reducing the cost of field power supplies.

  The network is linked to the internet by a radio link from PHILVOCS to the University of the Philippines (UP).  This link allows foreign organizations to access the data and provides basic internet services (mail, ftp, telnet,…) to PHILVOCS and any user located in the Taal vicinity.

  
  
• Title: Precise frequency generation with digital modulation using direct digital synthesis
  Author: J.L. Ong
  Abstract: 

  Frequency synthesis or generation of baseband continuous wave signals is usually implemented through traditional analog techniques using tuned LC tank circuits, quartz crystals or phase-locked loops.  This paper discusses a digital alternative, direct digital synthesis (DDS), and compares it with analog methods.  A commercially available DDS chip and the results of a DDS system implemented using it are also represented.

  
  
• Title: The Generic Network Modeling language (GNM)
  Author: E.D. Magtubo
  Abstract: 

  GNM is a language specifically designed to be the base language for the HERMES Project.  This language provides network engineers a tool for describing and designing a network topology.  With GNM, engineers can design their network in a graphical manner making it easier to be understood by other engineers.  This paper discusses the basic rules in using the language.

  
  

PEJ Vol. XVII, No. 2 December 1996

• Title: A productivity index model for Philippine Engineering Schools
  Author: A.C. Matias
  Abstract: 

  The measurements of the productivity of education systems necessarily rely on numerous interrelated aspects and judgements.  This paper illustrates an application of the concepts of multi-attribute utility evaluation of productivity for engineering educational institutions based on the assessment of deans of engineering schools/colleges in the Philippines.  The school administrators selected for the surveys and elicitation process were from school that offered both B.S. Chemical and B.S. Mechanical Engineering undergraduate programs.  Fifteen schools from the total list of 196 engineering schools (based on the official list of recognized engineering schools as of 1987, Technical Panel for Engineering Education) responded to the survey.  Five of these respondents were selected for the further development and assessment of the proposed model.

  Seventeen quantitative and qualitative measures of productivity were identified.  The assessment produced and additive multi-attribute function with a bilinear sub-model for quality and quantity of research outputs.  The model was tested using 4 engineering schools in the National Capital Region.  The model was partially successful in evaluating the performance of the selected schools.

  The potential application of the resulting aggregate measure is promising.  However, it will have to go through refinements and adjustments to be truly representative of the preference consensus of the different school administrators.  The development of a model relating the productivity index with a capability index is suggested as the most interesting extension of the model.

  
  
• Title: Coding telephone numbers to avoid “Wrong Numbersâ€�
  Author: E.F. Abaya
  Abstract: 

  “Wrong numbers” are an annoyance for owners of telephones. These incidents are due to several causes, of which the following two may be the most common: (a) pressing the wrong button on a telephone keypad, or (b) misreading a printed or handwritten telephone number.

  This paper presents two methods for developing numbering plans that will reduce the incidence of accidental wrong numbers when using push-button telephone sets by utilizing an error-detecting code on telephone numbers. It is demonstrated that small telephone numbering plans for 2 digits to 4 digits can be quickly generated by using a weighted code or by exhaustive search. Rotary dial phones are not considered in the paper.

  
  
• Title: Elasto-plastic soil-structure analysis by BEM-FEM substructure method
  Author: M.A. Zarco and T. Kuppusamy
  Abstract: 

  A method for solving soil-structure interaction problems which the infinite boundary effects of the far field domain is developed.  The method involves coupling boundary elements based on the Melan fundamental solution with finite elements in a manner so as to result in a system of equations which is both symmetric and banded. 

  Analyses of nonlinear soil-structure interaction problems such as bearing capacity, lateral earth pressure and U-frame lock construction problems are performed to investigate the far field domain effect.

  
  
• Title: Using solar energy to reduce heat stress in hot and humid offices – an alternative to conventional airconditioning
  Author: A.M.B. Santos and L. Gunnarsen
  Abstract: 

  Among heat acclimatized people, sweating is often quite efficient.  Supplying dried-only air to the immediate vicinity of office workers in hot and humid regions may be a promising low-cost alternative to traditional air conditioning. 123 heat-adapted subjects participated in six one-hour exposures in cubicles in a warm room without air conditioning.  Each subject had individually-adjustable air outlets both above and below the desk.  The temperature and humidity of the supply air was varied in a blinded and randomized design.  One exposure had no air supply.  At the end of each exposure the perceptions of subjects, water intake, skin temperatures, sweating and a simple performance measure were registered.  The supply of dehumidified but not cooled air significantly increased acceptability and reduced most of the monitored indicators of heat stress.  Solar energy was used in the air drying process and this may reduce the electricity consumption for drying considerably.

  
  

PEJ Vol. XVIII, No. 1 June 1997

• Title: Delamination in plastic packages
  Author: M.G. Mena
  Abstract: 

  Delamination or the disbanding of the plastic moulding compound from various surfaces and interfaces in a package integrated circuit is a major cause of reliability failures.  This paper reviews the causes of the said disbonding, the types of reliability failures that may be induced as well as various solutions available to prevent delamination.

  
  
• Title: Elimination of assembly-induced package cracks in plastic soic by
  Author: J.C. de Guzman , E. Epistola and M.G. Mena
  Abstract: 

  Considerable amount of information and knowledge is available on moisture-induced package cracking, especially on surface mount devices. During IC assembly itself, plastic packages are subject to thermal and mechanical stresses which may lead to package cracking or degrade package strength, thus making the package more susceptible to moisture effects. This study was conducted to characterize and understand assembly-induced package cracking in SOIC’s. Probable sources of thermal and mechanical stresses were identified by analyzing each station of the SOIC back-end assembly process. Each package cracking mechanism identified was defined in terms of its associated failure modes and rootcauses.

  The critical areas identified include mechanical deflashing, dambar removal, lead forming, singulation and IR ink curing. Mathematical models of the cracking mechanisms in these areas were developed and used to understand process input variables that affect the tendency of a package to crack. Evaluations, simulations and failure history reviews were then done to verify and substantiate the models with actual data.

  Process improvements were then defined based on the assembly input variables verified to be critical to SOIC package cracking tendency. These improvements include tooling modifications which reduces stresses during assembly, prevention and assignable causes through design and system improvements and tool life evaluations which eliminate potential sources of worn out tools. Package robustness measures such as anchor holes, improved tie-bar designs v-grooves and dimples were also analyzed. Process controls, monitors, contingency measures and short-looped reliability tests were likewise developed for early detection and containment package crack occurrences on the line.

  Results of the study showed that assembly-induced package cracking may be minimized through proper management of mechanical and thermal stresses at back-end assembly. Key areas identified include:

  • · Reduction of mechanical stresses through process and tooling design improvements;
  • · Elimination of process deviations and/or problems by using effective process controls and early detection monitors;
  • · and Package robustness enhancement schemes.

  
  
• Title: Moisture and thermal degradation of cyanate-ester-based die attach material
  Author: J.I.J. Gonzales and M.G. Mena
  Abstract: 

  Cyanate-ester-based thermo-setting die attach materials, commonly known as Low Temperature Die Attach (LTDA) are the newest innovation in Hermetic Die Attach Technology due to their improved manufacturability, high decomposition temperature and a moisture gettering effect. Although their dispensability and decomposition temperatures are well documented, little information is available on the effects of prolonged exposure to moisture and thermal conditions. A study was therefore conducted to investigate the behavior of LTDA under thermal and moisture conditioning.

  Results of the experiment showed that the LTDA initially exhibit weight loss and subsequent weight gain after prolonged exposure. Incorporation of the moisture into the polymeric structure was verified by Infrared Spectroscopy. Die shear strength was also observed to decrease exponentially with exposure time. The time-to-failure equation (10 kilograms die shear strength) as a function of temperature and humidity was established to follow the model.

  Calculations for shop floor condition (25 C/55%RH) show that an exposure time in the order of 106 hours is required for the die shear strength to degrade to 10 kilograms for a 224x225 mil die.

   

  
  
• Title: Thermal management in electronic packages
  Author: M.G. Mena
  Abstract: 

  Packaging of an integrated circuit not only involves the physical isolation of the delicate integrated circuit or “silicon chip” from the environment but also the provision of a thermal conduction path to allow the heat generated during the operation of the chip to be dissipated to the environment.  This paper presents the various types of failures accelerated by an increase in temperature of the integrated circuit and the modes of heat transfer through the packaging material. Characterization of the thermal characteristics of IC packages through the use of “thermal resistances” is also presented.

  
  
• Title: Variability in thickness measurements using x-ray fluorescence technique
  Author: I.C. Baltazar and M.G. Mena
  Abstract: 

  Thirty units of tin plated Dual In-line Packages were used to evaluate the measurement system for tin thickness using the X-ray Flourescence technique.  The results showed that the system is sensitive to inspector technique and the total measurement error estimate was about 22 microinches.  This system for obtaining tin thickness measurements had been recommended only when the variability of the process is at least 80 microinches.  Otherwise, a more sensitive method must be used.

  
  

PEJ Vol. XVIII, No. 2 December 1997

• Title: Characterization of coal ash
  Author: K. Nakagawa, K. Yamada, et. al.
  Abstract: 

  Coal ash samples were taken from Calaca, Thermal Power Plant in Batangas in 1993 and in 1996.  These coal ash samples were screened into different particle sizes.  Each particle size was analyzed for its moisture content, amount of unreacted carbon, mineral content and its fusibility.  The effect of the different particle sizes on the ash fusibility was investigated.  This is a sequel to a study conducted by Pugal, D.L. et al (1995).  Results of the characterization show that sieving coal ash samples into different particle size give higher sintering, softening and melting temperatures. Big particle sizes also have higher sintering, softening and melting temperatures than the smaller particle sizes.

  
  
• Title: Damage processes exhibited by WC-Co composite in rock drilling
  Author: N.M. Anacleto
  Abstract: 

  A study of the interaction of tungsten carbide-cobalt inserts with rocks and abrasive was carried out using an abrasive wear test and drop weight test.  In both tests, it was shown that the major mechanism of wear loss is associated with microfracture and/or fragmentation of WC grains.

  The study has also revealed that wear of WC-Co depends on the hardness and abrasiveness of the rock or abrasive.  The weight loss was found to be directly proportional to the number of blows during the drop weight test, while in the abrasive wear test, the weight loss was directly proportional to the hold down load and the traverse length.  An analysis of the results showed that the major wear process of the WC-Co inserts during rotary percussive drilling is impact damage and the contribution of sliding abrasion to the total wear is insignificant.

  
  
• Title: Design and development of a rice hull/biomass cookstove
  Author: B.L. Paita
  Abstract: 

  Biofuels from biomass abound from agricultural produce and waste, and from forestry products and aquatic plants.  Rice hull from rice biomass is a milling by-product which can be used as fuel for a variety of purposes including household cooking.  Similarly, coconut shell and husk are by-products and are used as biofuels.  Previous studies on rice hull stoves were reviewed.  A set of criteria was generated in order to incorporate desirable features for the new rice hull-biomass stove design.  Work to improve existing rice hull stoves focused on minimizing attention required to maintain an effective flame, which is normally done by disturbing the fuel bed.

  The implementation of the combined center-tube, conical grate, and nozzle stove principles led to the development of a novel rice hull-biomass cookstove capable of using a variety of biofuels such as sawdust, wood chips, coconut shell and husk.  Tests were conducted to evaluate the rice hull-biomass stove and the conical grate rice hull stove.  Heat utilization efficiency of up to 20% translates to more fuel available for cooking.

  
  
• Title: Failure investigation of high-chromium cast iron rolls
  Author: M.I. Espenido
  Abstract: 

  An investigation was made to look into the factors causing premature failures in high-chromium cast iron rolls.  It has been verified that firecracking which results from thermal fatigue serves as failure initiation sites and thus greatly limits the service life of rolls.

  Thermal fatigue mechanism is described and low it progresses to barrel breakage and spalling.

  
  
• Title: Indoor climate chamber design and performance.
  Author: R.A. Garcia, A.M. Santos and L. Gunnarsen
  Abstract: 

  Indoor climate studies have resulted in building codes which give a positive input to the lives of people.  However, knowledge about particular problems in hot and humid tropical climates is still limited.  Developing countries in hot and humid regions face particular restraints in the adoption of many technical solutions to indoor climate problems.  The installation and running costs of many solutions known from developed countries may be prohibitive.

  The Indoor Climate Laboratory is UP Mechanical Engineering’s response to this need for a better quality indoor environment in tropical climates especially when resources are limited.  Three climate chambers have been built and their performances are reported in this paper.

  
  
• Title: Investigation of long period oscillations in an enclosed harbor
  Author: E.R. Cruz and T. Aono
  Abstract: 

  Field measurements were conducted to verify and quantify the long period oscillations I Hiratsuka Harbor in Japan.  Time series data of water surface displacements were synthesized and wave statistics of the surf beat component obtained.  A nonlinear dispersive wave model was used to simulate the wave transformation around and within the harbor, using part of measured time series for the incident wave.  The measured time series, frequency spectra and significant wave statistics of the long period components at the gauging stations were adequately simulated in the computation.  Applications to the simulation of the wave field due to a critical wave for two harbor design scenarios are shown.

  
  

PEJ Vol. XIX, No. 1 June 1998

• Title: Applications of machine vision in agriculture
  Author: B.L. Paita
  Abstract: 

  Machine vision is an emerging field of technology that is expected to create a pervasive impact in the future.  A simple definition of machine vision is “the ability of a machine to see”.  As a sensory input, machine vision can be made a feedback to closed-loop control system such as robotic applications.  Sorting for quality and feature recognition are some of the most common applications of machine vision.  In this paper, the development of machine vision systems was reviewed and highlighted.  Several machine vision configurations are proposed that can be subjects of future research work.

  
  
• Title: Boiler performance of emulsified fuel
  Author: F.G. Manegdeg
  Abstract: 

   This research aims to show the performance of using emulsified fuel in a boiler.  Bunker and three (3) fuel mixtures consisting of different proportions of bunker, water and catalyst were tested using three (3) nozzle sizes.  Samples of the fuels tested including coal were subjected to fuel characteristic tests.  A batch mixer was designed and fabricated to blend the fuel mixtures.  The fuel mixtures were blended at the experimental sites using the formulated catalyst of the World Energy Extender Corporation.

  The process of emulsification done and the performance tests conducted are discussed in this study.  Fuel characteristics tests were performed based on the codes of the American Society for Testing Materials and the International Organization for Standardization. Boiler performance test were conducted based on the power test codes of the American Society of Mechanical Engineers.  A water tube boiler in conformity with Japanese Industrial Standard code was used.  It was observed that the thermal efficiency was lower when firing the boiler with fuel mixtures of bunker, water and catalyst than when only bunker was used.  This research only proves that these fuel mixtures can be used as alternative fuels.  It is recommended that further study should be conducted to improve and realize the full potential of emulsified fuels.

  
  
• Title: Denitrification of a high nitrate containing industrial wastewater in a suspended growth system
  Author: G.F. Parco
  Abstract: 

  The aim of this study is to evaluate the possibility of direct denitrification of concentrated wastewater, NO3-N concentrations of 1200-1760 mg/li. Special consideration was given to inhibition effects due to highly concentrated nature of the wastewater.  Based on this study a design for full scale application was made.  Chemostat trials were performed employing a 2 day residence time and batch trials were carried out to determine kinetic parameters ks and  μs.  Sludge from an existing oxidation ditch plant was used as innoculant.  Initial results in the chemostat trials showed inhibition occurring at 30% dilution of the wastewater. A high dilution ratios, equivalent to 60% dilution, washout occurred.  Various trials were used to determine the inhibiting component in the wastewater.  The carbon source was primarily ethylene glycol. Various interventions were investigated in order to overcome the inhibitory effect of which only dilution was seen as effective.  The inhibitory effect was assumed to be due to the effect of the carbon source.  Both the mono and di-ethylene glycol species were present in the wastewater of which the mono-ethylene glycol made up 80% of the total.  The glycol effect may be seen as affecting the microbial cells by increasing the osmotic pressure.  To overcome the glycol effect, it is necessary to dilute the wastewater.  A two reactor system was proposed to achieve denitrification while providing a source for dilution water.  The effluent from the first reactor, a denitrification reactor, was fed to an aerobic reactor where the remaining COD as glycol is oxidized and the effluent from this reactor is split and part if fed back to the denitrification reactor as dilution water and part is disposed of a final effluent.  A  mathematical model was proposed using both Monod and inhibition kinetics. Design charts at different dilution ratios were made from the resulting mathematical model.  The results show substantial denitrification results in the two reactor system depending on the dilution ratio employed.  It shows the possibility of direct denitrification by using a two reactor system while at the same time substantially decreasing the COD in the wastewater.

  
  
• Title: Highly active absorbent for SO2 removal prepared from coal ash (Part 1)
  Author: K. Nakagawa, K. Yamada, et al.
  Abstract: 

  Coal ash samples from Batangas Coal-Fired Thermal Power Plant and limestone from a cement plant in Bulacan were used as raw materials for the preparation of highly active SO2 absorbent.  The prepared SO2 absorbents were characterized to determine the effects of mineralogical composition, morphological structure and the type of coal ash used, on SO2 removal efficiency.  The desulfurization activity of the SO2 absorbents were determined by varying the curing conditions and CaO content.

  Among the coal ashes, fly ash exhibited the highest SO2 removal efficiency and longest effective absorption period.  The SO2 removal efficiency is closely dependent on the basic conditions during the preparation process of the SO2 absorbent.  The SO2 absorption activity increased with the reaction temperature and reached a maximum at 120oC for fly ash and 130oC for both bottom ash and slag.  Maximum SO2 removal efficiency was also attained by flash at 10 hour curing  period. Bottom ash and slag had high activity at 15 – 20 hours of curing time.  CaO content in the range of 20 ~30% will give a high SO2 absorption activity.

  
  
• Title: Membrane assemblages for dialysis separation of solutes
  Author: R.Q. Chu and L.M. Bellotindos
  Abstract: 

   This paper examines the performance of several configurations dialysis units for the separation of two solutes.  Dialyzers arranged in series, in parallel and the continuous column in countercurrent flow are studied.  The single dialysis unit is also included.

  For the recovery of the less permeable solute, the series configuration can give a good performance.  The parallel configuration favors the recovery of the more permeable component.  The continuous column has better capabilities for the separation and recovery of both the more permeable component and the less permeable component.

  
  

PEJ Vol. XIX No. 2 December 1998

• Title: Development of a centrifuge for high-speed centrifugal extraction of moisture from macerated water hyacinth
  Author: E.J. Calilung, D.Eng.
  Abstract: 

  Rapid mechanical dewatering of fibrous vegetative materials like water hyacinth requires separation of the process into two steps of maceration (cell breakage) and moisture extraction, to allow individual optimization for speed and efficiency. To fulfill the second step, centrifugal moisture extraction was explored. Centrifugal moisture extraction characteristics were determined using a fabricated batch loading centrifuge to determine its potential for rapid moisture extraction. A continuous-loading conical centrifuge was designed, fabricated and tested for continuous high-capacity moisture extraction from macerated of water hyacinth.

  Batch centrifuge test were conducted to establish the performance parameters for centrifugal moisture expression from macerated water hyacinth. The tests showed the following basic trends:

  • - Percent moisture extraction, weight reduction, and vegetable matter loss significantly increased with increasing degree of maceration.
  • - Percent moisture extraction, weight reduction, and vegetable matter loss increased as centrifugal acceleration was increased.
  • - Percent moisture extraction, weight reduction, and vegetable matter loss increased with increasing spin duration.

  Moisture and weight reduction were observed to exponential functions of spin duration and a critical spin duration of 5 seconds was determined for all treatments. Moisture and weight reduction were also found to be a linear function of centrifugal acceleration. Little change, however, resulted from increasing levels of centrifugal acceleration. Greater moisture and weight reduction resulted from increasing degree of maceration (through extrusion in a die ring with small hole diameter or several maceration passes). The target moisture reduction was attained at a centrifugal acceleration of 1341-g, 5 seconds spin duration and with the hyacinth macerated in a 6.35 mm die ring or twice macerated in a 12.70 mm die ring.

  
  To achieve higher throughput and better efficiency, a cone type continuous-loading centrifuge was designed, constructed and tested. The prototype, however, did not function properly due to the inherent difficulty of controlling the flow of fibrous macerated material up the conical screen surface. The material tended to form a mat that was difficult to break and which remained fixed on the cone surface. A system for controlled and positive displacement of the material along the conical screen surface should solve the problem, but will complicate the design, require high fabrication tolerance and increase machine costs considerably.

  
  
• Title: Highly active absorbent for SO2 removal prepared from coal ash (Part 2)
  Author: C.G. Magpantay, H.H. Bion, et. al.
  Abstract: 

  This paper is a sequel of previous study (Part 1) on the preparation of highly active absorbents for SO2 removal from coal ash and limestone.  The prepared absorbent from coal fly ash was tested for its desulfurization activity at varying conditions using the experimental SO2 absorption analyzer.  Simulated flue gas moisture used was composed of SO2, NO, CO2, O2 and H2O.  The activity of the produced absorbent closely depends on the method of preparation taking into account the effect of time and temperature for curing and drying.  The effects of particle size, surface are and % glass content were correlated with the SO2 removal efficiency.  The produced absorbent exhibited high efficiency not only for SO2 but also for NO removal at temperatures ranging from 100-165oC of the gas mixture.  NO serves as catalyst in the oxidation of SO2 to SO2 forming ettringite [Ca6Al2 (SO4)3(OH)1225H2O or 6CaOAl2O33SO33lH2O) and CaSO4 in the spent absorbent.

  
  
• Title: Soya oil as alternative fuel for diesel engine
  Author: F.G. Manegdeg
  Abstract: 

   The increasing concern on energy resources and the environment leads to a detailed analysis on the performance, emission and economy of compression ignition engine using alternative fuels.  The objective of this paper is to present and compare the performance and emission characteristics of diesel oil and soya oil as an alternative fuel over a range of compression ratio at constant speed and injection rate and at the experimented optimum injection advance for maximum power in a compression ignition engine.

  Results of the fuel property measurements indicate that the empirical chemical symbol of soya oil is C13H22.6O1.2 while diesel oil is C14.4H26.1.  Soya oil can release 87% of the energy released by diesel oil.  Soya oil has higher optimum injection advance for each compression ratio.  Operating at optimum injection advance for maximum power and at higher compression ratios (r = 19:1, 20:1), the brake mean effective pressure of soya oil is 95% of the brake mean effective pressure produced by diesel oil, and soya oil is 10% less thermally efficient than diesel oil.

  
  
• Title: The Engineering Innovation Center: Bridging the industry and the academe
  Author: Dr. Leopoldo V. Abis
  Abstract: 

  Commercialization of technologies through licensing and patenting has been practiced worldwide.  University-based licensing offices that bring university research and development outputs to the industry have become a major source of income for continued support for R & D activities.  Industries involved in the transfer of technologies have benefited well with their collaboration.

  The Engineering Innovation Center is the unanimous response of the University of the Philippines College of Engineering, the National Engineering Center, the University of the Philippines Alumni Engineers, and the U.P. Engineering Research and Development Foundation, Inc. in promoting commercially the R & D outputs of the U.P. College of Engineering and the National Engineering Center.  This paper presents the goals and strategy of Innovation Center as well as its present involvement and future plans.

  
  
• Title: The influence on temperature of noise, air velocity and window area during chamber tests
  Author: A.M. B.Santos
  Abstract: 

  When establishing the optimal level of an indoor climate parameter in a limited economy, there is often a cost expressed as a reduced comfort level for one or more of the other parameters.  Very little knowledge currently exists regarding optimal levels when two or more parameters are linked.  There is an obvious need for empirical determination of the trade-off between some of these parameters.  Thirty (30) heat-adapted subjects participated in ten 3.5 hour exposures in climate chambers.  Each subject had the option to change the air temperature in the chamber by adjusting a vote knob when prompted every five minutes.  The subjects were exposed to temperature linked with each of the parameters noise, air velocity and window area in a randomized design. In a reference exposure, temperature was not linked with the other parameters.  They were given instructions to optimize the climate in their respective chambers by adjusting the temperature while acknowledging the cost in one of the other parameters.  During the last 15 minutes of each exposure the perceptions of subjects, skin temperatures and simple performance measures were registered.  A warmer temperature was increasingly preferred when each of the parameters noise, air velocity and window area became more costly.

  
  

PEJ Vol. XX, No. 1 June 1999

• Title:  Material characterization and modeling of silicone putty using fractional derivatives
  Author: J.Y. Hernandez, Jr. and W. Tanzo
  Abstract: 

  Material characterization and modeling of materials being used in energy-dissipating devices is a prerequisite in the development of accurate models which can predict the behavior of these devices.  One such material in silicone putty used in the Shock Transmission Unit (STU).  This paper discusses the material characterization of silicone putty using a flat plate rheometer and its modeling using a fractional derivative maxwell model under low frequencies of loading.  The resulting constitutive equation is approximated using the Ll-Algorithm for fractional derivatives.

  
  
• Title: Behavior of carbon fiber reinforced concrete beams
  Author: F.J. German, J.L.Z. Locsin, et. al
  Abstract: 

  This test was undertaken for the purpose of demonstrating the increase in load carrying capacity of a plain reinforced concrete beam when reinforced with carbon fiber.  A presentation was also made to show the ease with which the carbon fiber reinforcement is applied, something that cannot be said of steel jacketing.  With regard to application, carbon fiber reinforcement is a more convenient alternative to the conventional steel jacketing technique for the rehabilitation of aging structures.  It weights substantially less than steel therefore it adds little, if any dead weight to the structure.  It is five times stronger and it does not corrode.  Deflections are also significantly reduced.

  
  
• Title: EEE student mortality-performance analysis
  Author: G.M.C. Denoga
  Abstract: 

  This is a study of student performance/mortality in the EEE curriculum for the UP EEE Classes of 1990 to 1996 based on student grades in the DEEERS database incurred within the time frame from 1991-1997 using Digital Signal Processing techniques, for the purpose of obtaining a measure of, and predicting a student’s course completion capability.

  
  
• Title: Highly active absorbent for SO2 removal prepared from coal ash (Part 3)
  Author: A.B. Herrera, H.H. Bion, et. al.
  Abstract: 

  In the Philippines, the government has started to impose environmental regulations to keep its environment free from hazardous and toxic element.  Among the detrimental pollutants being looked into, the government is focusing its attention to the hazardous emissions from coal-fired thermal power plants, in particular, to the reduction of Sox emissions.  ITDI has developed a process for the production of highly active absorbents for Sox removal using coal ash and limestone, raw or calcined, as its principal raw materials.  In previous studies, the chemical composition, mineral composition, morphological structure and thermal history of coal ash samples were determined to find out their effects on the preparation of the absorbents for Sox removal.  Studies on the production of Sox absorbents were conducted and the performance of these absorbents were measured.  In this particular paper, the effect of sieving the coal ash samples to obtain most reactive materials will be investigated.

  
  
• Title: Iso-annoyance lines for selected linked pairs of indoor climate parameters
  Author: A.M.B. Santos
  Abstract: 

  Most of the indoor climate research has been done in countries in the temperature region.  Many of these are developed countries having resources to build good buildings and for indoor climate research.  It has been a consensus in the developed societies that it is economically justified to aim at providing optimal indoor environments for students, office workers and others who work indoors.  Either legislators, designers and builders in developing countries in tropical regions are often forced to use the expensive and possibly inappropriate standards from developed countries or they may adapt solutions which have no formal scientific basis.  There is therefore a need for fundamental and applied research focused on the indoor climate needs of developing countries in hot and humid tropical regions.

  Achieving optimized partial improvements of the indoor climate may often be better than to know all optimal levels.  The purpose of this study was to investigate the relative importance of temperature, noise, draft and window area when two of these parameters are linked.  Thirty (30) heat-acclimatized subjects participated in 10 exposures in single person climate chambers.  Each exposure lasted three hours.  During an exposure, the subject was free to optimize the operative temperature at a link to either draft, noise or window area.  For each pair of parameters, three linear links were tested.  A reference exposure was furthermore included without any link.  Results show that a decrease in operative temperature of 1oC gives the same decrease in annoyance as approximately 0.1 /s decreased air velocity, 7 dB (A) decreased noise level or 0.5 m2 increase window area.  The used trade-off method may have numerous other research applications.

  
  

PEJ Vol. XX, No. 2 December 1999

• Title: An 8x8 starlite asynchronous transfer mode switch simulation
  Author: W. SM. Descallar, M.M.C. Tabangcura, et. al.
  Abstract: 

  Asynchronous Transfer Mode (ATM) is a new communications technology that is fundamentally and radically different from previous technologies.  Unlike other networks which can handle only one kind of traffic, this high-bit-rate, relatively low-cost technology can manage all the present types of communication media (voice, data, image, video, high quality sound, etc.) and can accommodate future possible applications in an integrated way.

  The most vital part of any ATM network is the switch that can be made up of a single stage of multiple stages.  Moreover, since the introduction of ATM, several switching architectures have been designed and implemented.  Several popular and commonly-used switches in the industry employ the Batcher-Banyan Multistage Interconnection Network configuration.  Starlite, Moonshine, and Starburst are some of the popular and commonly-used switches in the industry employing the Batcher-Banyan Multistage Interconnection Network configuration. The non-blocking Starlite Switch Design is chosen for implementation in this project because of its efficiency and broadcast-multicast capability.

  The objective of this project is to develop an ATM switch simulation using the CadenceTM VHDL (Very High-Speed Integrated Circuit Hardware Description Language) software that can model an 8x8 Batcher-Banyan Multistage Interconnection Network employing the Starlite approach.  It makes use of the GalileoTM synthesis tool to produce a file that can be translated into hardware and download into a Xilinxâ Field Programmable Gate Array.

  
  
• Title: Digital signal conditioning of bioelectric signals: a study of digital filter implementation
  Author: S.V. Rodriguez and R.C.L. Guevara
  Abstract: 

  This paper presents possible ways of implementing digital Finite Impulse response (FIR) filters in microprocessors to perform signal conditioning on biomedical electropotential signals, specifically electromyogram (EMG) and electrocardiogram (ECG). Digital filters are useful for these applications because of the flexibility offered by these filters as compared to their analog counterparts.  This study focuses on the FIR type of digital filers because of their potential to minimize the distortion introduced to a signal. Different FIR filter design implementations are presented in order to come up with a comparative performance of the different implementations.  The filters will be compared based on performance, accuracy, cost and complexity.  Requirements and recommendations will be made describing various alternatives in digital filter implementation.  

  
  
• Title: Emulsified fuel performance on compression ignition engine
  Author: F.G. Manegdeg
  Abstract: 

  The research aims to show the performance of using emulsified fuel in a compression ignition engine.  Diesel and four (4) fuel mixtures consisting of different proportions of diesel, bunker, water and catalyst were tested at various storage durations and engine parameters.  A batch mixer was designed and fabricated to blend the fuel mixtures.  It was observed that the thermal efficiency was lower when firing the engine with fuel mixtures of diesel, bunker, water and catalyst than when firing the engine with straight diesel.  The research however, proves that the fuel mixtures can be used as alternative fuels without engine modifications.  There is no substantial difference on the engine performance for all the tested fuels at various storage durations.

  
  
• Title: Increase in the dynamic force transmitted by a mass-spring-damper system model
  Author:  J.Y. Hernandez, Jr. and W. Tanzo
  Abstract: 

  The analysis of a mass-spring-damper system model shows a variation in the derived equation of the dynamic force transmitted compared to that of the applied force when the model is subjected to a sinusoidal displacement load.  Upon substitution of values, the force-time history plot shows a possible increase in the transmitted force.  This can be seen as the tilting of the principal axis of the corresponding hysteresis loop which implies an increase in stiffness.  This phenomenon was observed during the testing of the LOAD DISTRIBUTION and ENERGY-DISSIPATING (LDED) device.  The LDED device is effective in transmitting structure generated forces while dissipating a portion of the energy induced during earthquakes.

  
  
• Title: New controller implementation and force sensor instrumentation of a puma robot towards uncertainty identification
  Author: A.Chua, E. Calilung, et. al
  Abstract: 

   This paper presents a new design and implementation of an interrupt driven control system for a Puma 560 robot, which will provide the facility to implement true real-time control on a PC.  In the new controller design, the paper discusses the new hardware configuration, control system adopted, and software design implemented for the Puma robot.  Also, a controller tuning procedure was developed for robot joint dc motors to avoid oscillations and overshoot in their response.  The inverse kinematics implementation to the software controller will also be explained.  Finally, the paper also describes a force sensor integration that will be used together with the new controller for uncertainty (error) identification task.  This will include a discussion on the force sensor and its use, the safety system including watchdog timer and crash protector and some experiments to test the effectiveness of the force sensor in uncertainty (error) identification.

  
  

PEJ Vol. XXI, No. 1 June 2000

• Title: 32-Bit pipelined RISC microprocessor
  Author: Lee, L. Sangil, M.C. & Alarcon, L.
  Abstract: 

   The design of microprocessors is a crucial step in determining the over-all performance of a processing system.  A design technique may lead to several improvements in one aspect of processor performance but it may also worsen other aspects.

  In terms of the design of the instruction set, there are mainly two approaches of processor design.  The first approach, called Complex Instruction Set Computers (CISC), uses a few commands to implement complex instructions.  Ideally, this leads to shorter programs.  The other approach, called Reduced Instruction Set Computer (RISC), uses simple instructions to perform complex tasks.

  A key advantage of RISC over CISC is its suitability for pipelining.  Since the RISC approach implements simple instructions only, processing of instructions can be done in a parallel manner.  This implies that more operations can be executed at a single instruction cycle.  Hence, the technique of pipelining leads to higher throughput.

  The project aims to convert an existing implementation of a 16-bit non-pipelined RISC microprocessor into a 32-bit 5-stage pipelined RISC microprocessor.  The improvement of the previous project in terms of execution speed would be given focus so the layout size would have to be sacrificed.  The speed of the pipelined processor in executing a simple test bubble-sorting algorithm will be compared to that of the former project and the Motorola 6800.  Simulations ad the design itself would be implemented using CADENCE and Visual HDL 5.2.

  
  
• Title: Design and construction of a broadband Wilkinson power divider/combiner
  Author: R.C. Guevara
  Abstract: 

  Power dividers, directional couplers, and hybrid junctions are passive microwave components used for power division or power combining.  Power dividers often are of the equal-division (3 dB) type, but unequal power division ratios are also possible.  This paper describes the design, construction and characterization of a low loss broadband Wilkinson power divider/combiner implemented in microstrip using low cost FR4 and metal film resistor.  Major results include broadband DC-6 GHz frequency range, 0.0314 dB insertion loss above 3 dB, 38 dB isolation at the design frequency, 0.0o phase unbalance, 0.0334 dB amplitude unbalance, and a 1.0694:1 VSWR.

  
  
• Title: Implementation of a prototype ADSL system using TI TMS320C6X DSP
  Author: A.A. Manlapat, C.G.G. Santos, et. al
  Abstract: 

   The Asymmetric Digital Subscriber Line (ADSL) is a local loop transmission technology that simultaneously transports downstream (towards customer) bit rates of up to 8 Mbps, and upstream (towards network) bit rates of up to 800 kbps, and plain old telephone service (POTS) via a single pair of wires. The increased bandwidth available allows real-time applications like video-on-demand (VOD) live video conferencing and remote Local Area Network (LAN) access to be accessible via the public switched telephone network.

  This paper discusses the implementation of a prototype ADL system on the Texas Instruments TMS320C6701 Digital Signal Processor Evaluation Module.  The software blocks were coded and optimized in ANSI C and downloaded into the target system.  A simplified frequency scaled model of the subscriber loop is used as the channel in testing the system in loop back mode.  An online bit error rate test sequence was performed to determine system performance.  An aggregate bit rate of 66.15 kbps with a bit error rate (BER) of approximately 10-7 was achieved.

  
  
• Title: MP3 decoder using TI TMS320C6X DSP chip
  Author:  B.H. Galang, Jr. and L.Q. Quiwa
  Abstract: 

  MPEG I Layer III, more commonly known as MP3, is the de facto standard of digital audio compression.  It is an open standard for low bit rate coding of audio signals.  It is able to reduce an audio file up to a factor of 12 without losing fidelity-CD quality.

  This paper describes the theory behind MP3 and the implementation of ISO/IEC 11172-3 Audio Layer III decoding using the TMS320C6X Evaluation Module.  The software was written in ANSI C and it was cross-compiled through Code Composer Studio.

  The project is able to decode an MP3 file, store the result in a buffer and play the decoded segment using the codec of the evaluation module, or it can store the PCM samples as a raw file. This raw file can then be played using software such as Goldwave.

  
  
• Title: PCI Prototyping platform
  Author: R.T. Garcia, R.M. Sarte, and L. Alarcon
  Abstract: 

  Peripheral Component Interconnect or PCI, a high-speed bus technology is being considered as superior to other bus technologies when it comes to design and performance. Different adapters, which need fast accesses with one another or with system memory, can be connected to the PCI bus with the clock frequency approaching the processor’s full speed.

  The stringent electrical, functional, and timing specifications of PCI make it a formidable design challenge. A flexible PCI solution is needed to meet the current and the future requirements. Using a Very High Speed Integrated Circuit Hardware Description Language (VHDL) and Xilinx Field Programmable Gate Array (FPGA) Technology, a PCI prototyping platform car can be developed

  The PCI prototyping platform car will be implemented using PCI 32-bit wide bus implementation with a clock frequency of 33MHz. This card is capable of performing read and write transactions. Three registers will be provided for prototyping purposes. It is here where data can be read and written.

  The PCI prototyping platform car will be designed using VHDL and will be implemented using Xilinx FPGA technology.

  It is the objective of this project to develop and implement a PCI prototyping platform card capable of performing read and write transactions which will serve as a benchmark for future PCI-based projects.

  
  
• Title: Shifting to Innovation: Putting the Philippine microelectronics industry at the forefront of development
  Author: M. Tabangcura, M. Rafacon, et. al.
  
• Title: Text and binary-data transfer using postfix and UUCP over an HF radio link
  Author: I. Cabeza, M. Caccam, et. al.
  Abstract: 

  This paper discusses the first ever implementation of UNIX-TO-UNIX COPY (UUCP) and POSTFIX over an HF radio network.  It allows reliable text and binary data transfer between computer terminals several hundreds of kilometers apart.  The system was developed for use by PAGASA (Philippine Atmospheric, Geophysical, and Astronomical Services Administration) for collection of weather data from remote weather stations distributed around the country to a central server located in Diliman, Quezon City.

  
  
• Title: Viterbi convolutional error-correcting coder-decoder
  Author:  A.A. P. Chio and L.P. Alarcon
  Abstract: 

  In digital communications systems, it is common to use error-correcting codes to maintain reliable data reception.  Error correction coding adds redundancy to the input, and at the receiver, this redundancy is used to correct errors.  There are two types of error-correcting codes, block codes and convolutional codes.

  Convolutional codes are preferred over block codes in error-correction due to better reliability.  Although somewhat more complex when implemented, it is easier to decode.  Convulotional encoders are implemented using shift-registers and modulo-2 summers.  An (n,k,K) convolutional encoder accepts k bits input, and encodes it into n bits using K previous inputs and the present inputs.

  However, regardless of whether the coding is block or convolutional, the majority of the effort lies on the decoder, which needs to find the sequence which best corresponds with the noisy received sequence.  A well known decoder is the Viterbi algorithm, which produces a maximum-likelihood estimate and is optimal in minimizing the probability of error, given equally likely occurring information sequences.

  The Viterbi Algorithm performs a search of all the paths in the trellis diagram, and selects the most likely path traversed, which is then decoded as the original data.

  An optimally designed VHDL implementation VLSI architecture of a (3, 2, 3) convolutional encoder and error-correcting Viterbi decoder is aimed in this project.

  
  

PEJ Vol. XXI, No. 2 December 2000

• Title: A study on the state of the transportation environment in Metro Manila
  Author: K. Vergel and H.S. Lidasan
  Abstract: 

  In the 1990’s, the degradation of the atmospheric environment specifically air pollution brought about by the rapid increase in motor vehicle traffic, as reflected by the rapid increase in vehicle registration in 1988-1999, had become a major concern in Metro Manila, where a number of local and foreign agencies had conducted air pollution monitoring studies.  The objectives of this paper are to determine conditions and trends in the transportation environment, that is, the micro-environment of roads in Metro Manila and review urban and transportation policies of the government pertaining to the improvement of the transportation environment.

  These studies have conducted that total suspended particulates or particulate matter, followed to some degree, by nitrogen oxides and carbon monoxide, are the key air pollutants attributed to motor vehicle traffic.  Other pollutants such as oxides, total organic gases and lead are still below critical levels.

  The National Urban Policy Agenda of the NEDA deals on policies for the improvement of the urban environment and the transportation environment of Metro Manila through the urban environment management and Metro Manila policy modules, respectively.  Transportation policies through the DOTC deals on emission standards and inspection of motor vehicles through the Clean Air Act of 1999.

  
  
• Title: Characterizing process vitality in large Philippine manufacturing companies
  Author: A.B.S. Manalang
  Abstract: 

  As one of the key attributes of Total Quality Management Process Vitality represents the biggest in scope encompassing Product Design Management, Supplier Quality Management, Information and Analysis and Process Management.  The paper attempts to provide a model to characterize the level of maturity of large manufacturing companies in the Philippines using key indicators of Process Vitality.  Using multi-variate data analysis applied to a sample of 30 manufacturing companies, a predictive tool was developed to establish a taxonomy of companies on the basis of Process Vitality.  That the resulting taxonomy can be organized using graphical representation of the level of maturity is demonstrated in terms of multi-axial diagrams from which insights on a company’s plans, programs and procedures can be derived.

  
  
• Title: Conceptualizing a multi-attribute diagnostic model for total quality management
  Author: A.B.S. Manalang
  Abstract: 

  As part of an ongoing research on the development of a diagnostic tool for Total Quality Management, this paper attempts to conceptually define a quantitative assessment approach to measure the dynamic and multi-attribute characteristics of TQM.  From a synthesis of the various quality management approaches in the past, identified current practices and expert opinions, the level of TQM  adoption at the organizational level is found to be anchored on a systems structure composed of top leadership involvement, customer focus,  human resource empowerment, continuous improvement and process vitality as the characterizing attributes.

  
  
• Title: Evaluation and adaptive modification of a low cost paddy drying technology
  Author: P.C. Borlagdan, C. Diaz, and R.R. Bakker
  Abstract: 

  A low cost paddy drying technology originating from Vietnam was evaluated and modified to suit the local grain drying requirement.  The original design can dry one ton of wet paddy in 2 to 3 days depending on the moisture content and relative humidity of the drying air. Modification of the blower assembly and bin material significantly reduced the drying time compared to the original design.  The modified low cost dryer (LCD) can dry wet paddy with more than 24% moisture content, down to a safe level of 18% moisture content wet basis (MCwb) in ten hours.  The LCD was pilot tested with prospective end-users to solicit feedback and gauge its acceptability. The respondents compared the LCD with sun drying and suggested that if the dryer cannot dry paddy as fast as sundrying, it is not acceptable to them.  It takes 6 to 8 hours to sundry paddy during sunny days compared with 15 to 30 hours in the LCD. But sundrying is not possible during the wet season when it is needed most.  Farmers realized that the LCD would be very useful in saving the wet season harvest from deterioration.  LCD-dried paddy when milled has higher amount of headrice, comparable milling recovery and whiteness.  Testing and evaluation for lower capacities resulted in shorter drying time and lesser energy consumption.  Economic analysis showed that using the LCD during the wet season can be economically profitable, depending on the volume of grain dried.

  
  
• Title: Switched-capacitor filter for analog realization of a sinusoidal pulse width modulated induction motor drive
  Author: R.V. Andrada and L.G. Sison
  Abstract: 

  An analog implementation of a variable amplitude/frequency controller for a single phase DC-AC inverter with emphasis on its application for induction motor speed control is presented.  A clocked switched capacitor filter is used along with an operational amplifier integrator and a comparator to generate the bipolar sinusoidal PWM pulses for the output drive.  Variable frequency of operation is achieved by controlling the clock of the main controller while effective output voltage is automatically varied by the amplitude modulation ratio. It is demonstrated that the technique used is a novel and cost-effective approach in DC-AC inverter frequency control and has advantages over microcontroller-based and DSP-based methods.  This paper describes the basic concepts of the above VVVF-SPWM and preliminary test results of the prototype controller used for the experiment, which was constructed by integrating the controller with the associated driver, full bridge inverter (H-bridge) and deadtime controller.

  
  

PEJ Vol. XII, No. 1 June 2001

• Title: Adding value in rice production: A case study of women’s participatory evaluation of rice flour mill in Central Luzon, Philippines
  Author: T. Paris, C. Diaz, et. al.
  Abstract: 

  In the rural rice growing areas in the Philippines, conversion of milled rice to flour, particularly of glutinous varieties, is one of the traditional roles of women. Adding value to rice can be an important strategy in generating income of women. However, poor women still use the grinding stone in processing milled rice into flour. This requires considerable drudgery and takes too much time. Moreover, the output produced using this method, is wet flour which easily gets spoiled and contaminated. These constraints affect women’s potential in maximizing their income from processing rice food products. 

  This study was conducted: a) to test, and evaluate the technical performance, economic viability and its social acceptability by members of a women’s association; and; b) to identify the factors which can influence the successful adoption and sustainable use of this machinery at the village level. This study has shown that the rice flour mill has the potential for increasing women’s income. However, several factors should be considered such as: appropriateness of the technology, provision of \"hands - on\" training on the operation and simple trouble shooting of the machine to women, facilitate women to organize themselves, foster close collaboration between social scientists and agricultural engineers, use a gender sensitive participatory approach with the involvement of the men and women in each stage of the research process and to target for full capacity utilization of the machine for economic viability.

  
  
• Title: Basic study on traffic safety in Metro Manila: Traffic accidents in Quezon City
  Author: R.F. Regidor
  
• Title: Bluetooth host-side protocol stack development using formal design techniques
  Author: A.M.Q. Caccam, M.C. B. Dideles, et. al.
  Abstract: 

  Bluetooth is a wireless technology standard for the interconnection of electronic devices in the personal space.  It started out as a cable replacement technology and became a wireless persona networking (WPN) solution.  This paper describes the development of a Bluetooth Host-side Protocol Stack using Object-oriented and Formal Design Techniques such as SDL, ASN.1 and MSC. This marks the initial effort of the Advanced Science and Technology Institute in developing a complete System-on-a-Chip (SOC) solution within five years time.

  
  
• Title: Practical design techniques for FR4 material-based microwave hairpin filters
  Author: N.G. Toledo
  Abstract: 

  This paper presents practical design techniques for building hairpin filters using FR4 laminates.  This type of microwave microstrip filter is among the most popular low microwave frequency filters because of its compact size and ease of manufacturing.  However, building the hairpin filter using FR4 laminates is very difficult to do because of the relatively poor performance of the laminate at the microwave region. The motivation to use FR4 in the low microwave frequencies is its availability and inexpensive manufacturing process.  Methods and techniques were developed to address these problems of the FR4.

  
  
• Title: Small-scale Gold Mining Operations in Benguet and Camarines Norte, Philippines
  Author: E. Dlp. Clemente and L.J. Lanticse
  Abstract: 

  Small-scale gold mining in the Philippines has been practiced since the early 1900s. Today, however, with more than 100,000 families currently involved in the operation, more “modern” methods have been employed.  A more sophisticated system for mining the ore has been developed, and gold production is being done through amalgamation.  Inspite of the low efficiency of the method and the hazards to health, the people find amalgamation the most convenient method in terms of economics.  This paper reports the activities connected with the recovery of gold in the small-scale mining communities in Benguet and Camarines Norte.

  
  

PEJ Vol. XXII, No. 2 December 2001

• Title: A Comparative Analysis of Traffic Impact Assessment in the Philippines, Japan and South Korea: Implementation and the Use of Computer Simulation as an Analytical tool.
  Author: J.R.F. Regidor, H. Kubota and K. Sakamoto
  Abstract: 

  Traffic impact assessment (TIA) has become a necessity as cities and municipalities become aware of the potential impacts of new development on traffic flow. This paper compares the experiences of Japan and South Korea in the practice of TIA with that of the Philippines. The comparison is made with respect to their respective guidelines including the related laws and the TIA evaluation process followed in these countries. Four functions identified by the Institute of Transportation Engineers (ITE) are cited including forecasting and level of service analysis, and the tools developed and employed in aid of these functions are discussed. Computer simulation is presented as an invaluable tool for the analysis of traffic impact and examples are used to illustrate the utility of simulation including a comparison of simulation models condensed from the Japanese guidelines. Finally, recommendations on the application or implementation of TIA in the Philippines are proposed.

  
  
• Title: An Assessment Model to Characterize TQM Systems in Large Philippine Manufacturing Companies.
  Author: A.B.S. Manalang
  Abstract: 

   Current efforts in quality diagnostics are ineffective in providing organizations with a quantitative tool in the assessment of their level of Total Quality Management (TQM) adoption.  A survey questionnaire of quantitative measures was formulated from concept mapping results and, subsequently, administered across 40 domestic manufacturing companies from various industries with a capitalization of at least PhP 50 Million.  The latent statistical relationships among the variables were examined from which a long list of 28 validated key indicators was reduced to 18 variables using Principal Components Analysis and Multi-collinearity Analysis.  Through Multiple Linear Regression, the model structure of the relevant indicators characterizing the level of TQM adoption was established.  The resulting regression equation presents a classification model which confirms that the Level of TQM adoption is affected by the various indicators identified from the literature.

  From the reduced set of 18 variables, four relevant indicators surfaced as predictor variables for determining the level of Total Quality Management Adoption for the sample companies.  This exploratory work on large-scale companies highlights the possibility of organizing benchmarking efforts through quantifiable measures for continuously.

  
  
• Title: Exploring the Institutional Alternatives for Requiring Traffic Impact Assessment in the Philippines.
  Author: J.R.F. Regidor
  Abstract: 

  The UPNCTSFI Study Team that developed the guidelines for traffic impact assessment (TIA) proposed four mechanisms for institutionalization. These include incorporating TIA within the existing systems such as the Environmental Impact Analysis (EIA) required for environmentally critical projects and local government processes that give clearance for developments to be undertaken including those that will necessitate a change in the land use. This paper expounds on these proposed mechanisms, recommends a practical set-up and tackles the prerequisites for TIA to be applied in the Philippines. Capability building on the part of the government is discussed thoroughly, as well as the issues of accreditation and costs associated with TIA. As such the paper is able to achieve its primary objective of providing a comprehensive discussion on the institutionalization of TIA in the Philippines.

  
  
• Title: Inlfuence of Degredation Medium on the Partial Dissolution of Polyester Textile Sample.
  Author: E.Dlp. Clemente and E.R. Magdaluyo, Jr.
  Abstract: 

  Polymer degrades due to significant changes in its chemical structure, physical properties or appearances under specific environmental conditions.  When polymer is exposed to solutions, swelling and dissolution govern the degradation process.  Swelling or partial dissolution is characterized by the occurrence of cracks or stress fracture in the polymer fiber.  In this study, the chemical resistance of polymer textile sample to partial dissolution or swelling was examined.  The sample was exposed to solutions of different pH levels (NaHCO3-Na2CO3 buffer with a pH of 10.47; distilled water with a pH of 7.0 and HOAc-CaAc buffer with a pH of 4.67) for 142 hours.  After soaking, this was the surface characteristics were examined with the use of a Scanning Electron Microscope.

  Although indications of the formation of cracks were found, negligible weight loss was observed.  This implied the slow reactivity of the sample to the solution.  The onset of polymer degradation accelerated as the test reagent deviated from neutrality either way.

  
  
• Title: Numerical Issues Related to the Calculation of Consolidation Settlements
  Author: M.H. Zarco
  Abstract: 

   The evaluation of settlements due to consolidation is one of the most common computational procedures in geotechnical engineering. Recent research on this topic has indicated that current computational procedures underestimate consolidation settlements by as much as 70%. These errors are believed to result from the over-simplified manner by which the strains are numerically integrated.  In this paper, the magnitude and nature of these numerical errors is investigated. A series of numerical experiments are performed to study the effects of load intensity and type, depth of foundation, thickness of soil layer, and preconsolidation pressure on these errors.  Numerical errors are evaluated by comparing results obtained using the aforementioned procedures to either closed-form analytical solutions or numerical solutions using a high precision adaptive quadrature. Results of the numerical experiments indicate that such the underestimation of consolidation settlements is more pronounced in normally consolidated as well as heavily overconsolidated soils as compared to either lightly overconsolidated or underconsolidated soils. Recommendations are made regarding the proper use of the above-mentioned procedures in order to guarantee as sufficient degree of accuracy in the calculations.

  
  
• Title: Treatment of Dental Amalgam Wastes
  Author: E.Dlp. Clemente
  Abstract: 

  Extraction and recovery of Hg from dental amalgam waste was done by retorting and gravity separation.  It was found out that Hg exists in three phases in the dental amalgam waste slurry.  In the first phase Hg existed as a free metal.  557.2 g of free Hg was recovered from the three 300 ml. samples of dental amalgam waste.  The samples were first drained of water and then filtered using a nylon or linen cloth wherein Hg was easily squeezed out.  The filtrate, which is the dental amalgam alloy, was hand-panned to recover remaining free mercury that was not squeezed out of the cloth.  After panning, the dental amalgam alloy was air dried to remove excess water and to prepare it for retorting.  In the second phase, Hg existed in the dental amalgam waste alloyed in the amalgam.  The set amalgam will ideally consist of 50% Hg but it may contain as high as 60% and as low as 40% by weight.  Overall, 617.7 g of dental amalgam was collected from 900 ml of sample waste.  The dental amalgam was retorted, using a ThermEx® retort. For 30 min per 100 g of dental amalgam.  There was an average of 88.53% recovery.  From the expected recovery of 150 g, only 132.8 g were collected from the three trials.  This perhaps is an indication that the time of retorting may have been insufficient to ensure 100% recovery.  Moreover, the original amalgam alloy’s Hg-alloy ratio could have been lower than the ideal 1:1 ratio.  In addition, the manner or method of mixing of Hg with the dental alloy probably did not promote complete mixing during preparation thus failing to provide optimum absorption of Hg.  The third phase of Hg in the dental amalgam waste consists of the dispersed Hg in water.  Extraction of Hg from this phase will require a separate study.

  
  

PEJ Vol. XIII, No. 1 June 2002

• Title: A Numerical Model on Salt Migration in a Closed Unsaturated Fine Sand Column With Temperature Gradients.
  Author: Augustus C. Resurreccion
  Abstract: 

  Solute transport in the unsaturated zone in nonisothermal conditions has its important applications in the field of agriculture and groundwater quality modeling.  In this research, the phenomena of simultaneous transport of moisture, heat and solute in the unsaturated porous media are formulated by three partial differential conservation equations.  Numerical simulation and experimental study on salt migration is carried out in a closed unsaturated fine sand (Toyourra sand in Japan) column. Numerical discretization and solution are performed on the experimental domain with appropriate boundary conditions by iterative Picard technique Galerkin Finite Element Method. Results show that salt, in initial uniform water content and solute concentration, accumulates at the bottom due to heat source by salt precipitation and moisture convection.  The characterization of the identified hydraulic parameters with temperature is also discussed.

  
  
• Title: An Integrated System of Numerical Simulation and Visualization of Wave Penetration in Harbors.
  Author: Eric C. Cruz
  Abstract: 

  An integrated system of numerical simulation and graphic visualization of penetration by waves in harbors has been developed for use in Windows-based personal computers. This paper discusses the wave transformation model behind the computational engine, its numerical implementation, the design and integration of a graphical rendering sub-system, and the application of the system to both theoretical and practical wave penetration problems. The system is capable of simulating in space and time the three-dimensional wave field based on a set of vertically-integrated, phase-resolving equations accounting for wave nonlinearity and frequency dispersion in the shallow water region around a harbor, as well as in the deep water region in the offshore area. The visualization component has been designed to provide quick and meaningful representation of both input and transient variables, with diagnostic capability for the rendering of input parameters and post-processing capability for the synthesis of wave field statistics. The system is validated by applying it to fundamental wave propagation problems where analytical or measured data are available for comparison. The computational and visualization capabilities of the system are demonstrated by its application to wave penetration studies of actual harbors.

  
  
• Title: Life-cycle Environmental Benefits of Using Bioethanol as a Gasoline Additive.
  Author: Raymond R. Tan, Ph.D. and Alvin B. Culaba, Ph.D.
  Abstract: 

  Ethanol can be blended with gasoline as a fuel extender, an oxygenating agent, and octane enhancer.  Blends containing up to 10% ethanol by volume (E10) can be used in unmodified spark-ignition engines without significant changes in vehicle performance, while yielding reductions in over-all tailpipe emissions.  Enzyme-based processing technology is expected to allow ethanol to be produced commercially from cellulosic biomass such as municipal and agricultural waste as early as 2005.  Ethyl alcohol produced in this manner is called bioethanol; this production technology promises to be an effective open-loop recycling (“waste-to-energy”) pathway which simultaneously gives significant benefits of reduced fossil fuel consumption and air emissions.  This paper presents results of simulations using a modified version of the GREET 1.5a fuel cycle model to estimate the relative benefits of using E10 instead of conventional gasoline.  In addition to obvious savings in petroleum usage, reductions in life-cycle hydrocarbon, carbon monoxide, sulfur dioxide and carbon dioxide emissions are predicted by the model.  Cumulative emissions of particulates and nitrogen oxides, on the other hand, are expected to increase. 

  
  
• Title: Parametric and Kinetic Study of Silicon Nitride Film Deposition on Silicon Wafer by Low Pressure Chemical Vapor Deposition (LPCVD) Method .
  Author: Angelito A. Velasco
  Abstract: 

  Silicon nitride films were deposited on silicon wafers by Low-Pressure Chemical Vapor Deposition (LPCVD) method. Reaction gases were ammonia and 20% silane in nitrogen. The effects of (A) deposition temperature, (B) chamber pressure , (C) NH3-SiH4 flowrate ratio and (D) deposition time on the thickness of the film produced were studied using a full 2k factorial design. The film thickness was found to increase proportionally with temperature, pressure and time, and inversely with NH3-SiH4 flowrate ratio. Analysis of variance (ANOVA) shows that all main effects and interactions AC, AD, and CD were statistically significant at 99% confidence level. An interactive first order model was fitted to the experimental data:

  Y = 158.46 + 70.39X1 +26.86X2 – 66.44X3 + 74.45X4 –29.3X1X3 + 33.35X1X4

  – 30.68X3X4

  A kinetic study was also conducted in order to determine the rate equation for the growth of silicon nitride on silicon. The computed activation energy was 21.454 kcal/mol, which indicates that the surface reaction is rate limiting. The rate equation was:

  Deposition rate, nm/min = 37661.7 exp (-4578.5/T).

  Scanning electron micrographs show that the silicon nitride deposits appear as spherical-cap shaped clusters. Energy dispersive x-ray (EDX) and x-ray diffraction (XRD) analyses confirm the formation of silicon nitride.

  
  
• Title: Strength and Deformation Characteristics of Re-deposited Lahar from Mt. Pinatubo.
  Author:  Rolando P. Orense, Dr. Eng., P. E. and Andrew Zapanta, Jr.
  Abstract: 

  The 1991 eruption of Mt. Pinatubo caused extensive damage, with subsequent lahar flows covering widespread areas. Rehabilitation and reconstruction activities are currently being undertaken, with new buildings and other civil engineering structures being built over lahar-covered areas and roadway/river embankments being constructed using lahar materials. However, there is insufficient knowledge regarding the geotechnical properties of these volcanic deposits, especially their strength and deformation characteristics. To address this issue, an extensive research program was performed in order to investigate the geotechnical characteristics of freshly re-deposited lahar deposits from Mt. Pinatubo and to understand their behavior as materials for geotechnical construction. Freshly re-deposited samples were obtained at two locations: one upstream and another downstream from the volcano. In addition to engineering properties, permeability and compaction characteristics, the strength and deformation behavior in drained condition were investigated using the hollow torsional shear apparatus, with emphasis on the effects of relative density and confining pressure on the shear stress and volumetric change behavior. Moreover, the response of Pinatubo lahar during seismic loading was investigated by determining their cyclic deformation properties and liquefaction resistance. The findings obtained in this study can be used to formulate appropriate design methodology on the use of re-deposited lahar as geotechnical materials.

  
  

Volume XXIII, Number 1: June 2002 PEJ 2002;Vol.23 No.1

• Title: A Numerical Model on Salt Migration in a Closed Unsaturated Fine Sand Column With Temperature Gradients.
  Author: Augustus C. Resurreccion
  Abstract: 

  Solute transport in the unsaturated zone in nonisothermal conditions has its important applications in the field of agriculture and groundwater quality modeling.  In this research, the phenomena of simultaneous transport of moisture, heat and solute in the unsaturated porous media are formulated by three partial differential conservation equations.  Numerical simulation and experimental study on salt migration is carried out in a closed unsaturated fine sand (Toyourra sand in Japan) column. Numerical discretization and solution are performed on the experimental domain with appropriate boundary conditions by iterative Picard technique Galerkin Finite Element Method. Results show that salt, in initial uniform water content and solute concentration, accumulates at the bottom due to heat source by salt precipitation and moisture convection.  The characterization of the identified hydraulic parameters with temperature is also discussed.

  
  
• Title: AN INTEGRATED SYSTEM OF NUMERICAL SIMULATION AND VISUALIZATION OF WAVE PENETRATION IN HARBORS
  Author: Eric C. Cruz
  Abstract: 

  An integrated system of numerical simulation and graphic visualization of penetration by waves in harbors has been developed for use in Windows-based personal computers. This paper discusses the wave transformation model behind the computational engine, its numerical implementation, the design and integration of a graphical rendering sub-system, and the application of the system to both theoretical and practical wave penetration problems. The system is capable of simulating in space and time the three-dimensional wave field based on a set of vertically-integrated, phase-resolving equations accounting for wave nonlinearity and frequency dispersion in the shallow water region around a harbor, as well as in the deep water region in the offshore area. The visualization component has been designed to provide quick and meaningful representation of both input and transient variables, with diagnostic capability for the rendering of input parameters and post-processing capability for the synthesis of wave field statistics. The system is validated by applying it to fundamental wave propagation problems where analytical or measured data are available for comparison. The computational and visualization capabilities of the system are demonstrated by its application to wave penetration studies of actual harbors.

  
  
• Title: Life-cycle Environmental Benefits of Using Bioethanol as a Gasoline Additive.
  Author: Raymond R. Tan, Ph.D.a and Alvin B. Culaba, Ph.D.b
  Abstract: 

  Ethanol can be blended with gasoline as a fuel extender, an oxygenating agent, and octane enhancer.  Blends containing up to 10% ethanol by volume (E10) can be used in unmodified spark-ignition engines without significant changes in vehicle performance, while yielding reductions in over-all tailpipe emissions.  Enzyme-based processing technology is expected to allow ethanol to be produced commercially from cellulosic biomass such as municipal and agricultural waste as early as 2005.  Ethyl alcohol produced in this manner is called bioethanol; this production technology promises to be an effective open-loop recycling (“waste-to-energy”) pathway which simultaneously gives significant benefits of reduced fossil fuel consumption and air emissions.  This paper presents results of simulations using a modified version of the GREET 1.5a fuel cycle model to estimate the relative benefits of using E10 instead of conventional gasoline.  In addition to obvious savings in petroleum usage, reductions in life-cycle hydrocarbon, carbon monoxide, sulfur dioxide and carbon dioxide emissions are predicted by the model.  Cumulative emissions of particulates and nitrogen oxides, on the other hand, are expected to increase. 

  
  
• Title: Parametric and Kinetic Study of Silicon Nitride Film Deposition on Silicon Wafer by Low Pressure Chemical Vapor Deposition (LPCVD) Method .
  Author: Angelito A. Velasco
  Abstract: 

  Silicon nitride films were deposited on silicon wafers by Low-Pressure Chemical Vapor Deposition (LPCVD) method. Reaction gases were ammonia and 20% silane in nitrogen. The effects of (A) deposition temperature, (B) chamber pressure , (C) NH3-SiH4 flowrate ratio and (D) deposition time on the thickness of the film produced were studied using a full 2k factorial design. The film thickness was found to increase proportionally with temperature, pressure and time, and inversely with NH3-SiH4 flowrate ratio. Analysis of variance (ANOVA) shows that all main effects and interactions AC, AD, and CD were statistically significant at 99% confidence level. An interactive first order model was fitted to the experimental data:

  Y = 158.46 + 70.39X1 +26.86X2 – 66.44X3 + 74.45X4 –29.3X1X3 + 33.35X1X4

                               – 30.68X3X4

  A kinetic study was also conducted in order to determine the rate equation for the growth of silicon nitride on silicon. The computed activation energy was 21.454 kcal/mol, which indicates that the surface reaction is rate limiting. The rate equation was:

  Deposition rate, nm/min = 37661.7 exp (-4578.5/T).

  Scanning electron micrographs show that the silicon nitride deposits appear as spherical-cap shaped clusters. Energy dispersive x-ray (EDX) and x-ray diffraction (XRD) analyses confirm the formation of silicon nitride.

  
  
• Title: Strength and Deformation Characteristics of Re-deposited Lahar from Mt. Pinatubo.
  Author: Rolando P. Orense, Dr. Eng., P. E. and Andrew Zapanta, Jr.
  Abstract: 

  The 1991 eruption of Mt. Pinatubo caused extensive damage, with subsequent lahar flows covering widespread areas. Rehabilitation and reconstruction activities are currently being undertaken, with new buildings and other civil engineering structures being built over lahar-covered areas and roadway/river embankments being constructed using lahar materials. However, there is insufficient knowledge regarding the geotechnical properties of these volcanic deposits, especially their strength and deformation characteristics. To address this issue, an extensive research program was performed in order to investigate the geotechnical characteristics of freshly re-deposited lahar deposits from Mt. Pinatubo and to understand their behavior as materials for geotechnical construction. Freshly re-deposited samples were obtained at two locations: one upstream and another downstream from the volcano. In addition to engineering properties, permeability and compaction characteristics, the strength and deformation behavior in drained condition were investigated using the hollow torsional shear apparatus, with emphasis on the effects of relative density and confining pressure on the shear stress and volumetric change behavior. Moreover, the response of Pinatubo lahar during seismic loading was investigated by determining their cyclic deformation properties and liquefaction resistance. The findings obtained in this study can be used to formulate appropriate design methodology on the use of re-deposited lahar as geotechnical materials.

  
  

Volume XXIII, Number 2: December 2002 PEJ 2002;Vol. 23 No. 2

• Title: DIRECT DATA TRANSFER OVER THE HOST CONTROLLER INTERFACE OF THE BLUEZ BLUETOOTH® PROTOCOL STACK IN BAYANIHAN LINUX V2.0
  Author: William R. Cheung*, Joel T. Fallorina* and Janice M. Ballesteros
  Abstract: 

  The Bluetooth specification defines a whole protocol stack necessary for a standardized interface of different Bluetooth devices. One of the layers in the stack is the Host Controller Interface (HCI). It serves a vital role in interfacing the higher and the lower parts of the stack. This paper discusses the implementation, setup, and testing processes involved in directly utilizing the HCI layer in sending and receiving data. An application was developed on top of Bayanihan Linux v2.0 which has built-in Bluez, the official Linux Bluetooth protocol stack. The application shows the operations and functions of the HCI layers in transferring data. Accessing the HCI layer directly will have several advantages, one of which is the reduced overhead from higher layers.  The setup was tested with a 3COM USB Adapter and a 3COM PCMCIA Card.

  
  
• Title: MODELING OF DELAY-INSENSITIVE CIRCUIT BUILDING-BLOCKS USING THE HAMBURG DESIGN SYSTEM
  Author: Jesse M. Sacayanan and Joel R. Noche
  Abstract: 

  The operation of delay-insensitive circuits, a class of asynchronous logic circuits, is difficult to visualize.  Models of delay-insensitive circuit building-blocks are created using the Hamburg Design System (HADES), a pure-Java framework for object-oriented component-based simulation.  These models help designers and students visualize the operation of delay-insensitive circuits.

  
  
• Title: SYNTHESIS AND CHARACTERIZATION OF RPET/ORGANO-MONTMORILLONITE NANOCOMPOSITES
  Author: Blessie A. Basilia1, Herman D. Mendoza, Dr. Eng.2 and Leonorina G. Cada, Ph.D.3
  Abstract: 

  Recycled polyethylene terephthalate (RPET)/organo-montmorillonite nanocomposites were synthesized by direct melt intercalation method. The effect of this processing technique in the nanomorphology, thermal stability and mechanical behavior of the intercalated products were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), small angle x-ray scattering (SAXS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and mechanical analysis. The difference of using recycled PET (RPET) vis-à-vis virgin PET (VPET) as matrix in the polymer nanocomposites, using synthesized Philippine organo-montmorillonite or commercial organoclay as the layered-silicate, was evaluated. •Results showed that direct melt intercalation by twin-screw extrusion method gave generally exfoliated structures especially at <5% clay loading, based on powder XRD patterns. SAXS patterns and HRTEM micrographs revealed laminated structures at the basal (001) reflections resulting to a d-spacing of 14nm in localized areas not observed by powder diffraction. Higher levels of orientation of the layered silicates were obtained with commercial organoclay compared with the synthesized clay. Thermal degradation has been decreased and tensile strength increased with the increase in clay loading. RPET resin was intercalated in a similar manner with VPET in the layered silicates of Philippine organo-montmorillonite.

  
  
• Title: SYNTHESIS OF PB-FREE BI-2223 FROM BI-2212 USING PARTIAL MELTING
  Author: M.U. Herrera and R.V. Sarmago
  Abstract: 

  Synthesis of Pb-free Bi-2223 has been made possible by partial melting. Partial melting was done by sintering the samples below the melting point of Bi-2212 thus allowing the dissociation of the weak bonds of BiO layer to exhibit fluid-like planar movements. Volume fraction of Bi-2223 increases with temperature which was attributed to the increase in fluid-like movements. Also, the samples sintered at long sintering time of 50hrs and 100hrs show larger volume fraction of Bi-2223 as compared with those sintered at 25hrs. The involvement of fluid-like planar movements during the partial melting process was supported by the presence of fused-grain boundaries, layered structure, and hole-like features seen in the Scanning Electron Microscopy images.

  
  
• Title: THERMAL STABILITY STUDY ON TITANIUM DISILICIDE (TISI2)
  Author: Venezuela, Jeffrey DG and Amorsolo, Jr., Alberto V. PhD.
  Abstract: 

  Titanium disilicide (TiSi2) has largely been used as gates and interconnects in semiconductor devices due to its low resistivity and good thermal stability. This work aimed to study the thermal stability of titanium disilicide thin film capped with titanium nitride based on measurements using the atomic force microscope (AFM) and four-point probe apparatus. Capped and uncapped silicide thin film samples, produced from the same initial thickness of Ti film (60 nm) on (111)-Si substrate but subjected to different rapid thermal processing schemes to form the silicide, were annealed at 950oC at varying annealing times (10, 20, 30, 40, 50 and 120 minutes). Morphological changes associated with thermal degradation were determined using both the AFM and scanning electron microscope (SEM). The changes in both the film’s surface roughness and sheet resistance were also monitored over these annealing times. Results indicate  significantly higher root mean square (RMS) surface roughness and sheet resistance in the uncapped sample after 120 minutes annealing implying better thermal stability in the capped than in the uncapped sample. The efficacy of TiN in increasing the thermal stability of TiSi2 is attributed to originate from a retardation of material diffusion in the silicide layer.  Also, atomic force microscopy was successfully applied to understand the thermal stability of the TiN-capped silicide.

  
  

Volume XXIV, Number 1: June 2003 (Part 1) Special Issue

• Title: Abstracts of Thesis and Dissertations, College of Engineering, U.P. Diliman, 1993-2003
  Author: The Editor-in-Chief
  Abstract: 

  For the benefit of engineering researchers and practitioners, we are publishing the June 2003 Special Issue of the Philippine Engineering Journal as a compilation of abstracts of MS Theses and PhD Dissertations in Chemical Engineering, Civil Engineering, Electrical and Electronics Engineering and Computer Science, prepared by graduate students of the College of Engineering, University of the Philippines Diliman, during the period 1993-2003. In December 1992, the Journal had a similar special issue with the compilation of abstracts of MS theses and PhD dissertations during the period 1981-1992.

  It has often been said that some of the research output of the academe, such as graduate engineering research, are not being adequately disseminated among potential users of the newly gained knowledge and information. In most instances, the expertise and knowledge developed by few graduate students remain confined in their persons and do not grow by multiplier effect through an exchange brought about by the media of print and fora. Toward this end, this special issue is providing a medium for reaching more users in the respective engineering fields. Hopefully, they may find in the abstracts the key to the solutions of their own particular problems, whether practical or theoretical in nature.

  As necessary aids to researchers, we are furnishing both author and subject indices of the thesis or dissertation titles. Each title is accessioned by a character code which consists of an engineering field identified (3 characters, a year index (4 digits), and a sequence number (2 digits).

  We hope that with this special issue we would be able to reach and inform potential beneficiaries of research information who are based in the country and abroad. After another a period of years, we hope to publish another similar issue in order to disseminate abstracts of more theses and dissertations, developed especially in the newly instituted MS and PhD programs of the UP College of Engineering, including those under the Engineering Research and Development for Technology (ERDT) program.

  
  

Volume XXIV, Number 2: December 2003 (Part 2) Special Issue

• Title: Abstracts of Thesis and Dissertations College of Engineering, U.P. Diliman, 1993-2003
  Author: The Editor-in-Chief
  Abstract: 

  For the benefit of engineering researchers and practitioners, we are publishing the June 2003 Special Issue of the Philippine Engineering Journal as a compilation of abstracts of MS Theses and PhD Dissertations in Energy Engineering, Environmental Engineering, Industrial & Operations Research Engineering, Mechanical Engineering, Mining, Metallurgy & Materials Science Engineering and Remote Sensing, prepared by graduate students of the College of Engineering, University of the Philippines Diliman, during the period 1993-2003.  In December 1992, the Journal had a similar special issue with the compilation of abstracts of MS theses and PhD dissertations during the period 1981-1992.

  It has often been said that some of the research output of the academe, such as graduate engineering research, are not being adequately disseminated among potential users of the newly gained knowledge and information.  In most instances, the expertise and knowledge developed by few graduate students remain confined in their persons and do not grow by multiplier effect through an exchange brought about by the media of print and fora.  Toward this end, this special issue is providing a medium for reaching more users in the respective engineering fields.  Hopefully, they may find in the abstracts the key to the solutions of their own particular problems, whether practical or theoretical in nature.

  As necessary aids to researchers, we are furnishing both author and subject indices of the thesis or dissertation titles.  Each title is accessioned by a character code which consists of an engineering field identified (3 characters, a year index (4 digits), and a sequence number (2 digits). 

  We hope that with this special issue we would be able to reach and inform potential beneficiaries of research information who are based in the country and abroad.  After another period of years, we hope to publish another similar issue in order to disseminate abstracts of more theses and dissertations, developed especially in the newly instituted MS and PhD programs of the UP College of Engineering, including those under the Engineering Research and Development for Technology (ERDT) program.

                 

  
  

PEJ Vol. XXV, No. 1, June 2004 PEJ 2004; Vol. 25 No. 1

• Title: An Opportunity Cost-Based Modified Genetic Algorithm for the P-k Media Problem
  Author: Joanna Z. Resurreccion1 and Augustus C. Resurreccion1
  Abstract: 

  Median problems are combinatorial problems that associate the allocation of demand points to the selection of different location sites for a number of facilities that satisfy the total demand.  This study focuses on the P-k median problem of minimizing the total weighted distance between n demand points and these location sites when the number of existing facilities, k, on a given network is increased to P.  Initial combinations of possible locations for the additional P – k facilities are iteratively improved using a proposed modified genetic algorithm.  The algorithm implements a new opportunity cost-based child reproduction procedure for the generation of better solutions with biased parent selection probabilities.  This creates the best possible offspring without affecting the locations of existing facilities while current information from having the existing k facilities simplifies the choice of locations for increasing the number of facilities from k to P.  The generated combinations of facility locations are tested on the Galvao-100 median set deriving 30 P-k median problems from the Lagrangian relaxation solutions.  Average percentage difference from the optimal solution found at 0.52% outperforms the neighborhood search improvement made on the myopic algorithm at higher values of P-k.

  
  
• Title: Analyzing Impacts of Transportation Infrastructure and Policies on Traffic Flow in
  Author: Jose Regin F. Regidor
  Abstract: 

  Various transportation infrastructure and policies have been implemented in the Philippines in order to ease traffic congestion and other transportation and traffic problems.  Many of these are in Metro Manila, comprising a long list that includes grade separation devices, traffic control facilities, and vehicle restraint measures.  These have been generally perceived to have positive impacts and have led to the construction of more infrastructures or the continued implementation of traffic schemes.  Nevertheless, there are sectors that have not taken advantage of available impact assessment techniques and tools to systematically and properly evaluate the effects of infrastructure and policies on transportation and traffic.  This paper presents the most popular methods and some tools for appraising effectiveness of infrastructure and policies.  Several examples are discussed and results are used in formulating recommendations regarding best practices in impact assessment.

  
  
• Title: Characterizing the Spatial Pattern Changes of Urban Heat Island in Metro Manila
  Author: Rosalyn A. Pereira and Epifanio D. Lopez
  Abstract: 

  This study characterizes the spatial pattern of urban heat island (UHI) phenomenon when in situ measurements are not available. Images obtained from remote sensors operating in the thermal infrared wavelength of Lands at Thematic Mapper ™ and Enhanced Thematic Mapper (ETM+) were used to derive the surface temperature of Metro Manila from 1989 to 2002; thereon, the formation of urban surface heat islands became apparent. The impact of urbanization to surface urban temperature is noticeable – the average annual rate of urban growth is found to be 1.33 percent while the rise of UHI has an annual growth rate of 0.8 degrees Celsius. Likewise, increase in lad surface temperature is related to the decrease in leaf biomass. These were evident from changes in land cover parameters such as fractional vegetation cover and surface moisture availability. These parameters were derived by computing the normalized difference vegetation index (NDVI) from the images.

  
  
• Title: Development of a Car Ownership Model in Metro Manila
  Author: Caesar P. Rubite1 and Christopher C. Tiglao2
  Abstract: 

  The Metro Manila region has been continuously growing swiftly over the past years. This rapid urbanization in the city center has spilled over its periphery, the adjoining municipalities. Accessibility between the outer periphery and the city center becomes very critical especially when people seek employment within the city center. With the lack of efficient transit system on one hand, and improved socioeconomic characteristics of the household on the other, the demand for private cars is expected to increase also. However, the limited supply of road space cannot keep pace with increasing demand. Therefore, it is necessary to manage the growth of car ownership in metropolitan areas. A basic understanding of individual and household attitudes towards car ownership would enable the formulation of effective policies and plans for managing car ownership. Knowledge of car ownership paves the way for a better understanding of the people’s behavior which will greatly affect policy formulation and analysis in the future.

  The research is concerned with determining the various household characteristics which influence the household’s decision to own a car. This decision is modeled as a binary choice incorporating the different household and individual characteristics as explanatory variables. The study used data taken from the Metro Manila Urban Transportation Integration Study (MMUTIS) Home-Interview Survey (HIS) database. The research revealed that the major factors affecting household decision to own a car are household income and number of working adults.

  
  
• Title: Effect of Percentage Alumina on the Growth Kinetics of Copper and
  Author: Angelito A. Velasco, Charmaine Florable A. Digsay & Jennifer M. Balajediong
  Abstract: 

  In this paper, the effect of the amount of alumina reinforcement on the growth kinetics of copper grains during the early stages of sintering and hardness of the composite was investigated.  Samples were obtained by mixing the powders of copper and alumina of different compositions (5% and 10%wt alumina) and compacting at 3,000 psi. Sintering is done using a tube furnace in a nitrogen atmosphere for varying times (10, 20, 40, 80, 160 minutes) and temperatures (750oC, 850oC, 950oC). Afterwards, the samples were prepared for metallographic examination and the average grain size of copper was  measured.  Photomicrographics showed an increase in copper grain size and decrease in porosity with increasing temperatures.  From the kinetic study, the following grain growth equations for 5% alumina and 10% alumina copper-matrix composite were obtained.  Hardness measurements were performed using the Vickers Hardness Tester.  Higher hardness of the composite was attained at increased temperatures and % alumina.

  
  

PEJ Vol. XXV, No. 2, December 2004 PEJ 2004; Vol. 25 No. 2

• Title: A Study on Roadside Noise Generated by Tricycles
  Author: Karl N. Vergel1 Frielly T. Cacho2 and Cheryl Lyne E. Capiz3
  Abstract: 

  The study is aimed at quantifying the levels of noise contributed by tricycles in the roadside residential environment.  Specific objectives include the measurement of roadside noise levels, relating noise levels and road traffic flow characteristics and relating noise performance of tricycle with loading, speed and road gradient (sloping or level) at on-road conditions, and with type of engine, loading, fuel-oil mix ratio and type of lubricant at simulated loading conditions.  Tricycles comprise majority of the traffic passing through the study area.  Results from the 24-hour survey of noise levels have shown that all readings exceeded the existing local standards.  A multiple linear regression model predicting roadside noise level as a function of the traffic speed and tricycle traffic volume is developed with a relatively high correlation, indicating the significant contribution to noise by tricycles.  There is a relationship of on-road noise performance of tricycles with its speed and load and type of road.  With respect to noise performance under simulated loading, there is an increase in noise level with increase in speed level.

  
  
• Title: Comparing Diesel Fuels at Various T90 Distillation Temperatures: Engine Performance, Vibration and Emissions
  Author: Gerald Jo Denoga and Edwin N. Quiros
  Abstract: 

  The performance of a Diesel engine was evaluated using fuels with varying T90 distillation temperatures.  The T90 distillation temperature is an indicator of the yield of Diesel fuel extracted from crude oil.  A higher T90 can translate to better utilization of raw petroleum resources.  This experiment verified if high distillation temperatures have any effects on torque, power, specific fuel consumption and emissions.  Engine vibrations were also measured and analyzed using accelerometers.  Tests were done on a light truck engine connected to a chassis dynamometer.

  
  
• Title: Development of Drive Cycle and Emission Concentration Models for in-use Tricycles in Metro Manila
  Author: A.A. Abuzo1, R.G. Sigua2 & K.N. Vergel2, 3
  Abstract: 

  The objectives of the study are to develop the drive cycle for the tricycle, the local three-wheelers used for public transport in the Philippines, and quantify emissions from these vehicles as well as determine some of the factors that affect the emissions.  The drive cycle for tricycle is developed with a maximum speed of 43.0 kph, maximum acceleration of 6.97 m/s2 (minimum acceleration of 6.44 m/s2), and average speed of 19.94 kph. Results indicate that 4-stroke tricycles have lesser HC and concentration is significantly affected by fuel-oil ratio and loading.

  
  
• Title: On the Use of Entropic Regularization for Identification of Cohesive Crack Parameters
  Author: Norbert S. Que
  Abstract: 

  The fracture parameters governing the cohesive crack model is obtained through the use of entropic regularization. Specifically, it is employed as a smoothing technique that lends to the solution of a difficult identification problem cast as a mathematical program with equilibrium constraints (MPEC). Results suggest that reformulation of MPEC as a nonlinear programming problem using entropic regularization show promise in the solution of the parameter identification problems considered in this paper.

  
  
• Title: Slope Failures Triggered by Heavy Rainfall
  Author: Rolando P. Orense
  Abstract: 

  Landslides occur frequently during or following periods of heavy rainfall. This is illustrated by the large-scale landslides and debris flows in Quezon Province which were triggered by a series of typhoons and tropical storms last November-December 2004. In order to understand the mechanism and conditions leading to these slope failures, a comprehensive testing program consisting of constant shear stress drained triaxial tests and model slope experiments was performed using sandy materials obtained from a former landslide site in Japan. Results of both element tests and model experiments clearly showed that slope failure is induced due to the development of pore-water pressure in slope. As soil moisture contents within the slope approach critical values, ground deformations are mobilized. Therefore, by properly selecting regions where soil moisture contents must be monitored, possibly in areas where seepage forces will develop, failure initiation in slopes can be predicted. Based on this, a simple monitoring scheme to predict in real-time the occurrence of failures in critical slopes was proposed.

  
  

PEJ Vol. XXVI, No. 1, June 2005 PEJ 2005; Vol. 26 No. 1

• Title: A Path Planning Algorithm for Soccer Playing Robots Based on Repeated Modification of Bezier Polynomials
  Author: Michael Angelo A. Pedrasa
  Abstract: 

  The Bezier curvature algorithm is a path-planning algorithm for soccer robots based on repeated modification of Bezier polynomials. The robot is steered by choosing an appropriate Bezier curve that connects its current position and its destination, and the robot is made to traverse the initial section of the curve. The wheel velocities of the differentially-driven robot are computed from the curvature of that curve section. The process is repeated until the robot finally reaches its destination. The algorithm was compared to two other path-planning algorithms for soccer robots: the uni-vector field and line-circle algorithms. The algorithms were made to execute 17 tests cases and their performances were compared. The tests cases have different robot, ball and obstacle locations. The objective of the robot is to kick the ball towards the center of the target goal. The goal success rate, kicking accuracy and frequency of collisions were compared. The results showed that the principles behind the Bezier curvature algorithm are valid, and it performed better than the two algorithms.

  
  
• Title: Combining Local and Global Features for Offline Handwriting Recognition
  Author: Rhandley D. Cajote and Rowena Cristina L. Guevara
  Abstract: 

  The result of investigating the performance of handwriting recognition systems using local features, global features and a combination of local and global features is presented.  The global features are derived from the shape of the word contour and the local features are derived from the geometric characteristics of the word segments.  The global features utilize the centroidal distance of the word contour also known as the polar-radii graph or PRG.  The system was trained and tested using the demo version of the publicly available IAM database.  Using the local features alone and an HMM recognizer a recognition rate of 58% was achieved using a 20-word vocabulary.  Using the PRG of the word contour as a global  feature and an MLP classifier a recognition rate of 78% is achieved.  The PRG is then combined with the local features using a combined probabilistic framework and the hybrid handwritten word system achieved a recognition rate of 72%.

  
  
• Title: DC Current Measurement Using Magnetic Flux in an Electronic Null Balancing Arrangement
  Author: Miguel T. Escoto, Jr.
  Abstract: 

  DC current measurement using magnetic flux balancing with an automatic controller is presented.  A ferromagnetic, toroidal core is used both as a flux detector and magneto motive force summer element.  A symmetrical, AC triangular current sent through an excitation coil builds up flux in the core.  The DC current to be measured is sent through another coil, which sets up a bias magneto motive force or mmf.  The bias mmf causes the core to reach saturation earlier on one side of the flux build up than on the other side.  As core saturation is reached, a voltage pulse transition is detected in a separate winding by a Schmitt trigger.  Its duty cycle varies with the amount of flux imbalance affecting an automatic control feedback which strives for zero flux, be sending an opposing current, through a fourth coil, producing a canceling flux.  An electronic null balancing circuit was wired to verify the technique.

  
  
• Title: RF Characterization of Square Spiral Inductors on a 0.25 µm Digital CMOS Process
  Author: John Richard E. Hizon1, Marc D. Rosales1, Louis P. Alarcon1 & Delfin Jay Sabido IX2
  Abstract: 

  The growth of wireless applications in the low GHz range has been a catalyst in numerous research activities to develop wireless applications in standard digital CMOS processes. The relatively lower costs in developing single chip solutions for wireless applications in CMOS technology is considered its main advantage over other semiconductor processes.  Thus, with the integration of RF systems in CMOS, planar inductors will have a dominant role in defining the achievable performance of the system as a whole.

  The inductors used in this study were used in the input impedance matching for an LNA at 2.4 GHz.  Plain square spiral inductors and square spiral inductors with Q enhancement structures are implemented on a 0.25 µm digital CMOS process with inductance values of 1.8 nH and 10 nH. On Wafer RF characterization of the inductors were done using an inductor model proposed by Yue. Results obtained show that parasitic resistance limits the Q of square spiral inductors on a digital CMOS process.  Measured results also show how Q enhancement techniques reported in literature affect inductor Q on a digital CMOS process.  It is recommended that shunted metals be used in improving inductor Q.

  
  

PEJ Vol. XXVI, No. 2, December 2005 PEJ 2005; Vol. 26 No. 2

• Title: Assessment of Traffic Inputs to Pavement Design and Rehabilitation
  Author: Jose Regin F. Regidor, Romeo A. Damaso II and April Rose V. Bilugan
  Abstract: 

  Traffic and the consequent loads that vehicles transfer to the roads are major factors considered in pavement design. Heavy vehicles, particularly trucks that carry the largest loads cause the most damage to pavements. In the design process, axle loads attributed to heavy vehicles are derived and the total equivalent standard loads are estimated over a design period. The total loads are then utilized in coming up with the appropriate design that takes into account pavement type and thickness, among others. This paper analyzes the traffic inputs to pavement design through assessment of actual highway sections along the Pan-Philippine Highway also known as the Doña Remedios Trinidad Highway. Original design loads due to previous projections of traffic is compared to present loads and new projections of future traffic loads. As such, pavement performance level could be gauged and the adequacy of current pavement types and thickness can be determined. Recommendations are formulated and proposed in relation to the importance of accurate traffic inputs in pavement, especially the development of heavy vehicle factors that allow for a more accurate estimation of equivalent axle loads as well as implications to economic design of pavements.

  
  
• Title: Corrosion Behavior of Steel Bar in Chloride Contaminated Mortars with Fly Ash
  Author: Marish Madlangbayan1,2, Nobuaki Otsuki1, Takahiro Nishida1 and Melito Baccay3
  Abstract: 

  In this study, the corrosion behavior of steel in mortars with fly ash was investigated.  Electrochemical measurements including the half-cell potential, current density, anodic polarization and cathodic polarization were performed.  The test results showed that corrosion current densities in chloride contaminated by fly ash mortars with longer curing are within the passivity limit.  Also, from the anodic polarization curves, the passivity grades in chloride contaminated fly ash mortars with longer curing were the same as Ordinary Portland Cement (OPC) mortars which indicates that mortars with this binder can provide passivity to steel bars as effective as OPC mortars.  Moreover, by cathodic polarization test, fly ash mortars exhibited the ability to reduce oxygen availability which leads to enhancement in corrosion performance.

  
  
• Title: Performance of a Watergy Audit on the Submersible Pumps of the Talamban
  Author: Joseph Gerard T. Reyes1, and Carl F. Odulio2
  Abstract: 

  As part of its efforts to promote awareness of energy-efficiency in water-production and distribution companies in the Philippines, the Alliance to Save Energy (ASE) partnered with two provincial public water utility companies, one of which was the Metropolitan Cebu Water District in Cebu City.  With the application of a methodology developed by the ASE and the Energy Research Institute (TERI) of India, a Watergy audit was performed on the submersible pumps of production wells within a selected raw water system of the MCWD, situated in the town of Talamban, Cebu City.  The results of the audit led to the identification of opportunities for improvement of the pumps’ performance and the formulation of recommended feasible measures toward attaining energy-efficiency.

  
  
• Title: The Relation Between Preparation, Microstructure and Mechanical Properties of Alumina Ceramics
  Author: L. dela Cuesta2, M. Mena1, G.N. Sison1, S. Bernardo1, S.J. Cho3 and K. Uematsu4
  Abstract: 

  The starting alumina powders were synthesized by chemical method under varied pH conditions – pH 6.5 and pH 8.5. The resulting powders were characterized by fine particle sizes, high surface area and crystalline structure. Powders at pH 8.5 were noted to have finer particle size than at pH 6.5. Due to their fine characteristic, the powders agglomerated during preparation of compacts.

  The alumina compacts were fabricated by (1) cold isostatic press (CIP) and sintered at 1550â—‹C and 1650â—‹C and (2) hot isostatic press (HIP) and also sintered at 1550â—‹C and 1650â—‹C. The CIP compacts showed large grains of alumina, whereas the HIP compacts were relatively fine-grained. The microstructure of both compacts exhibited abnormal grain growth more particularly in the CIP compacts.

  The synthesized powders were contaminated with Ca which accounted for the abnormal grain growth in both alumina compacts. The Ca present in HIP fabricated alumina compacts at pH 8.5 and sintered at 1650â—‹C, gave high flexural strength. This was due to the formation of fine-elongated grains of regular pattern in between the fine-grains in the alumina matrix. The Ca present in the CIP fabricated alumina compacts at pH 8.5 and sintered at 1650â—‹C gave relatively low values of flexural strength. Flexural strength of alumina compacts fabricated by HIP at pH 8.5 significantly increased with an increase in sintering temperature.

  For HIP alumina compacts at pH 8.5, fracture toughness increased with an increase in sintering temperature. Such increase in toughness was due to the growth of needle-like grains.

  
  
• Title: Value-Based Utility Broker for Jitter Management of Voice on IP Networks
  Author: Jhoanna Rhodette I. Pedrasa1, and Cedric Angelo M. Festin2
  Abstract: 

  A variety of scheduling algorithms and management frameworks have been proposed to provide more than just best-effort service offered by the Internet Protocol. A new framework, Value-Based Utility (VBU), uses the perceived knowledge of the state and degree of user satisfaction in managing router resources and functions. VBU has been shown to effectively manage packet loss and delay in times of high demand and low resource availability. This paper applies VBU to jitter management by enhancing on two existing scheduling algorithms, namely Stop-and-Go and Jitter-EDD. Our results show that Stop-and-Go with Utility can achieve a tighter jitter bound of T, where T is the frame length, which is half of the original bound of 2T offered by Stop-and-Go alone. VBU has limited application however to Jitter-EDD, where the rigid environment restricts the re-allocation of resources according to demand.