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ASEAN Journal on Science and Technology for Development

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Published by Universitas Gadjah Mada

ISSN : 22249028 EISSN : 22249028 DOI : -

Core Subject : Science, Education, Engineering,

Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Computer Science & IT Mathematics

The coverage is focused on, but not limited to, the main areas of activity of ASEAN COST, namely: Biotechnology, Non-Conventional Energy Research, Materials Science and Technology, Marine Sciences, Meteorology and Geophysics, Food Science and Technology, Microelectronics and Information Technology, Space Applications, and Science and Technology Policy, Infrastructure and Resources Development.

Arjuna Subject : -

Articles 477 Documents

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STUDY OF PREPARATION AND CHARACTERIZATION OF HYDROXYAPATITE COATINGS BY SOL-GEL TECHNIQUE Sutapa Roy Ramanan; Ramanan Venkatesh
ASEAN Journal on Science and Technology for Development Vol. 19 No. 1 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Hydroxyapåtite (HAP) coatings were prepared on glass substrates by sol-gel dip coating method, using a isopropanol solution of calcium nitrate and 2-butanol solution of phosphorous pentoxide as starting precursors and mixing them to get a coating solution with Ca/P ratio of 1.67. The prepared coatings were dried at 150°C and subsequently fired at 500°C to obtain dense coatings. Multilayer coatings were prepared to increase the final thickness. For some samples, SiO2, TiO2, Al2O, and Zr02 coatings modified the interface between the glass and HAP. X-ray diffraction, scanning electron microscopy, FTIR and DTA/TG were used for characterization. All the coatings obtained at 500°C in air had only crystalline hydroxyapatite phase, characteristics FTIR signature peaks of HAP and dense and smooth morphology with the apparent presence of micropores. The cross-sectional microstructure of the coatings showed presence of smooth interface.

MITIGATING CO EMISSIONS FROM THE POWER SECTOR: LEAST-COST ANALYSIS OF POLICY OPTIONS IN THAILAND Bundit Limmeechokchai; Somporn Tanatvan; Ram M. Shrestha
ASEAN Journal on Science and Technology for Development Vol. 19 No. 1 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Traditionally, the method used in the electricity generation expansion planning has concentrated only on the supply-side options to identify the sequence of generation additions meet the forecasted demand at a minimum cost. Electricity generation expansion planning with both supply- and demand-side options, commonly known as integrated resource planning are also being used in some developed countries. With growing environmental concerns, especially the emission of air-pollutants from the power generation, demand-side management and clean and efficient generation technology options in the power sector development are getting increasing attention. In this paper, we compare the traditional planning approach with integrated resource planning. We also analyze the implications of CO2 reduction targets for the power sector development in the framework of supply side planning by including clean supply-side technologies as candidate plants. During the planning horizon, generation capacity of 365 MW and a cumulative electricity generation or 61,681 GWh would be avoided through the use of efficient demand-side technologies compared to the business-as-usual (BAU) case. When the clean supply-side options considered in the least-cost planning process, three units of 100-MW biomass-based plants are selected. The long run average cost of generation is found to increase by 0.32, 0.65 and 1.61% at the level of CO2 emission reduction target of 5, 10, and 20%, respectively.

STEADY STATE FINITE ELEMENT ANALYSIS OF A SINGLE STACK COLD PLATE WITH HEAT LOSSES G. A. Quadir; Shiao Lin Bell; K. N. Seetharamu; A. Y. Hassan
ASEAN Journal on Science and Technology for Development Vol. 19 No. 1 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Steady state analysis of a single stack cold plate used for the cooling of electronic components is carried out using the finite element method. The present methodology takes into account the heat losses from the top and bottom surfaces of the stack. In addition dimensionless parameters are used in the analysis. The analysis is divided into two parts: a single unit cell analysis and the analysis of the assembly of several unit cells. The results from the present analysis of a single unit cell for single stack cold plate without heat losses compare well with those available in the literature. The analyses of the assembly of unit cells with heat losses from the top and bottom surface of the stack show that the single unit cell can be considered to be the representative of the stacks only when there are no heat losses.

THERMAL DIFFUSIVITY MEASUREMENT OF SOLID USING PYROELECTRIC SENSOR B. Z. Azmi; Y. T. Ling; M. Hashim; W. M. M. Yunus; M. M. Moksin
ASEAN Journal on Science and Technology for Development Vol. 19 No. 1 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The recently developed pyroelectric spectroscopic technique has been used to measure the thermal diffusivity of solids. The method has been applied to conductors and insulator where by the thermal wave is measured at various lateral distances on the sample between laser illuminated line and pyroelectric sensor position. The thermal diffusivity is obtained from the gradient of the plot of thermal wave signal versus the lateral distance. A good agreement to the previously reported thermal diffusivity value has been obtained for aluminium, copper and spray paint that is 0.809 cm2s-1, 1.128 3cm2s-1 and 1.547 x 10-3 cm2s-1 respectively.

USING CRUDE PALM OIL (CPO) AS DIESEL ENGINE FUEL T.H. Lim; S. Bari; C.W. Yu
ASEAN Journal on Science and Technology for Development Vol. 19 No. 2 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

In this study, heating was used to lower the viscosity of CPO to an acceptable level. 60°C was found to be the optimum heating temperature for CPO to ensure smooth flow in the fuel system, but heating further up to 100°C did not improve the engine performance. A comparison between CPO and diesel in terms of engine performance, combustion characteristics and emission showed that the brake specific fuel consumprion (bsfc) for CPO was 13% higher at 400 kPa brake mean effective pressure (bmep), and the highest bmep achieved was 13.5% lower. However, CPO fuel gave a brake thermal efficiency. Combustion analyses indicated that CPO combustion produced a 7% higher peak pressure, a 3.3-degree earlier ignition and an 11.6-degree longer burning duration, but a 26% lower peak heat release rate. After 500 hours of running CPO, performance and power of the engine dropped even while running with diesel. With a 26% higher bsfc and a 20% lowe maximum bmep. Visual inspection of the dismantled engine parts discovered heavy carbon deposits but normal wear. Overhaul of the engine restored the power and performance.

CATALYTIC ACTIVITY OF ZSM-5 ZEOLITE LOADED WITH TRANSITION METALS FOR THE SELECTIVE CATALYTIC REDUCTION OF NOX I.M. Saaid; A.R. Mohamed; S. Bhatia Bhatia
ASEAN Journal on Science and Technology for Development Vol. 19 No. 2 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Catalytic activity measurement were carried out on catalysts formulated from ZSM-5 zeolite separately loaded with transition metals (Cu, Co, Ni, Fe) for the removal of NOx in simulated diesel exhaust conditions. Various factors were investigated to compare the performance of these catalysts including catalyst preparation method, Si/Al ratio of the parent zeolite support, and durability in the exhaust stream containing water vapor or SO2. In many experimental conditions except in the presence of water vapor or SO2, Cu-ZSM5 remained the most active catalyst with 100% NOX conversion at around 350°C. C0-ZSM5 and Ni-ZSM5 could also achieve complete NOx conversion but at a much higher temperature of around 450°C. Fe-ZSM5 catalyst was the least active catalyst probably due to the formation of iron oxide particle, which accelerated formation of carbon monoxide.

GIANT MAGNETORESISTANCE (GMR): SPINNING FROM RESEARCH TO ADVANCED TECHNOLOGY K.Y. Kok; I.K. Ng
ASEAN Journal on Science and Technology for Development Vol. 19 No. 2 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

In this paper, we aim to examine the research and development of materials demonstrating the giant magnetoresistance (GMR) property, a novel material property that has revolutionalised the advances of magnetic sensor and mass-memory technology today. A comprehensive outline for the fundamental materials aspects as well as the physics of the underlying mechanisms behind the GMR property is given. Recent development of GMR materials in data storage industry and other potential technological applications exploiting the GMR property are also discussed.

USING TWO TIME SCALES OF TURBULENCE FOR BOUNDARY LAYER FLOWS Nawaf H. Saeid
ASEAN Journal on Science and Technology for Development Vol. 19 No. 2 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

A near wall improvement of the k-? model of turbulence is proposed and evaluated. The present model takes into account the asymptotic behavior of turbulent scales near wall region and for free turbulence region. The Kolmogorov turbulent time scale is introduced as a lower limit. The model is used for prediction of turbulent boundary layer flows. Predictions compared with experimental data of several flow cases, with encouraging results.

FACTORS AFFECTING REFRIGERATOR-FREEZERS ENERGY CONSUMPTION R. Saidur Saidur; H.H. Masjuki; T.M.I. Mahlia; A.R. Nasrudin
ASEAN Journal on Science and Technology for Development Vol. 19 No. 2 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Two frost-free household refrigerator-freezers, one with 492 liter capacity and one with 460 liter capacity were tested in the laboratory to determine the sensitivity of several variables those influence consumption refrigerator-freezers energy consumption greatly. The effects of single variables such as room temperature, thermostat setting positions, and door openings on the energy consumption were investigated. Using Response Surface Methodology (RSM), a mathematical model has been developed to investigate the combined effect of room temperature, thermostat setting positions, and door opening on the energy consumption of refrigerator-freezers. From the mathematical model, it has been observed that room-temperature has the highest effect on the energy consumption followed by the thermostat setting position. The door opening has lowest on the energy consumption. More detailed tests were performed under different room temperature, thermostat setting positions, and door opening conditions and presented in this paper.

PERFORMANCE OF MEMBRANES CROSSLINKED WITH GLUTARALDEHYDE IN PERVAPORATION SEPARATION S.H. Tan; A.L. Ahmad; M.G. Mohd. Nawawi; H. Hassan
ASEAN Journal on Science and Technology for Development Vol. 19 No. 2 (2002): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Chitosan membranes crosslinked with glutaraldehyde (GA) were prepared through a solution method, where the dry homogeneous chitosan membranes were immersed into the reaction solutions containing 1.25 x 10-3 wt. % of glutaraldehyde (GA). The extent of the crosslinking was controlled by varying the crosslinking time from 1 to 5 minutes. The prepared crosslinked membranes were used for pervaporation dehydration of isopropanol-water mixtures. The influence of feed composition on the separation characteristics has been investigated. The 2-minute-crosslinked-membrane yields the highest water concentrations in the permeate with moderate flux at 50 wt. % of isopropanol in the feed solution. The overall pervaporation results for the homogeneous and crosslinked membranes are compared in term of pervaporation separation index (PSI). The crosslinked membranes showed higher pervaporation separation index (PSI) than that of uncrosslinked membranes especially for isopropanol in feed solution below 78 wt. %.

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