Volume 12 (2000)

Table of Contents

No. Article


1. Perubahan Kekuatan Mampatan Konkrit Muda Terhadap Amplitud Relatif Gelombang Ultrasonik (The Changes of Compressive Strength of Young Concrete into Relative Amplitude of the Ultrasonic Waves)
Kamarudin Mohd Yusof & Mohammad Fauzi BahariAbstract
Grade 20 and 30 of young concrete paste with water-cement ratios 0.5 and 0.6 have been studied using ultrasonic wave. The young concrete paste ages between one day and 28 days have been tested with an ultrasonic combined method. Relative amplitude of pressure wave, amplitude A and velocity Vp of the ultrasonic wave parameters have been measured for the compressive strength of the young concrete. Moisture content of the young concrete paste was also been studied to determine its effect on the concrete paste parameters in relation to the compressive strength. The relative amplitude the pressure wave amplitude A and the pressure wave velocity of the ultrasonic wave showed clearly that the parameters varied with the change of the compressive strength. However the effect of moisture on these parameters are also large and therefore the effect of moisture on the measurement should be taken into account.

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2. Pemisahan Zarah Mengguna Teknik Ayak: Kesan Parameter Pengoperasian Ke Atas Kecekapan (Particle Separation Using Screening Technique: Effects of Operation Parameters to the Efficiency)
Siti Masrinda Tasirin & Chang Wun ChingAbstract
Separation of solid mixtures of different particle sizes into two size grades by means of a screening surface is widely used. For thousands of years the fundamental principle of screening has been and still is maintained. Despite of the advantages such as easy operation and low cost of maintenance, the overall efficiency of the process is of importance for optimization purposes. In this case, investigation on the effect of several operating parameters such as time, vibration frequency, percentage of coarse (oversize) in the feed material and total loading on the overall efficiency of the separation process has been carried out using solid mixtures of sand and glass beads. A general form of empirical correlation has been obtained, from which suitable operation conditions for optimum process efficiency may be determined.

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3. Pengaruh Penggantian Sebahagian Pasir Dengan Debu Kuari Ke Atas Ciri Konkrit Prestasi Tinggi Baru (The Influence of Partial Replacement of Sand With Quarry Dust on the Properties of New High Performance Concrete)
Muhammad Fauzi Mohd.Zain, Sudharshan Naidu Raman & Md. SafiuddinAbstract
This study discusses the influence of partial replacement of sand with quarry dust on the properties of fresh high performance concrete. Considering the decrease in the sources of natural sand, it is necessary to identify alternative source, such as quarry dust to reduce the utilisation of sand in the industries, which requires it. In this study,replacement proportion of sand with quarry dust that was practised was 20% in all the high performance concrete mixes except in the normal Portland cement control high performance concrete mix. The properties of fresh high performance concrete were determined in the aspects of slump, slump flow, V-Funnel flow, air content,density and temperature. Results obtained showed that partial replacement of sand with quarry dust was able to increase the workability and flowability, and also the air content of fresh high performance concrete. Besides that, it was observed that V-Funnel flow was more suitable to determine the flowability of fresh high performance concrete compared to the conventional slump flow.

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4. Pencirian Proses Penyediaan Titanium Silisida Untuk Kegunaan Saling Hubung Litar Bersepadu CMOS (Characterization of the Titanium Silicide Process Preparation for the Application of Interconnection in CMOS Integrated Circuit)
Uda Hashim, Burhanuddin Yeop Majlis & Sahbudin ShaariAbstract
Characterization of the titanium silicide process preparation for the application of interconnection in CMOS integrated circuit has been characterized. The process characterize are titanium deposition, selective wet etching, native oxide removal and thermal budget adjustment of reflow- anneal borophosphosilicate glass. Titanium film was sputter-deposited at various times by PVD system. The relationship between titanium deposition time and film thickness is plotted. The relation Y = 3.8X0.89 which was generated by the graph is employed to determine deposition time at any specific thickness. The solution which is the mixture of NH4OH, 30% H2O2, H2O (1:1:5) for solution 1, H2SO4 10% HF, H2O (30:1:69) for solution 2, and H2SO4 30% H2O2 (1: 1) for solution 3 have been tested for titanium selectivity wet etching. Base on the calculation, the etching rate of the solution 1, 2, and 3 are 0.15 nm/s, 7.8 nm/s and 1.16 nm/s, respectively. The wafer, which is dipped in the HF solution before titanium deposition revealing a better silicide/silicon, interface after heat treatment process. The reduction thermal budget of BPSG reflow-anneal from 900°C to 850°C for 30 minutes using furnace couple with additional anneal at 950°C for 60 seconds rapid 60 seconds rapid thermal annealer revealed the same surface topography with the wafer that annealed at 900°C for 30 minutes using conventional furnace.

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5. Pemodelan Pemilihan Kenderaan Bagi Perjalanan Antara Bangi dengan Kuala Lumpur (Modelling of the Transport Selection for Travelling Between Bangi and Kuala Lumpur)
Riza Atiq O.K.Rahmat & Lim Wai YipAbstract
Modelling the modal choice of transport is an important step in urban transport planning. In this study, modelling the transport modal choice of Bandar Barn Bangi residence going to work in Kuala Lumpur was conducted. The trip makers have three choices of transport mode, that is call commuter train and bus. Motocycles and taxis are ignored due to their in extensive usage for this kind of trip. It was found that monthly income, travel cost (including parking charges) and travel times are the main factors that influence the transport choice. The relationships of these variables to the transport choice were formulated in the form of trip end model and trip interchange models. In the trip end model, two stages decision structure with logistic function was adopted. Monthly income was found to give a good probability ode. In the trip interchange model, a single stage decision structure with multinomial logic function was adopted. The developed model was found out to closely replicate the actual transport mode choice when independent variables such as monthly income, travel cost by cal travel time for both modes of transport and the ratio of fare charges monthly income of commuter train and bus were included in the model.

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6. The Ignition Probabity Study of Reinformed Fuel to Characterise for New Automotive Fuel
Yusoff AliAbstract
As we approach the next century, the scientists recognize that our supply of fossil fuel is limited. Hence, more efficient use of the fossil fuel are required. This paper give some possible use of new catalytic system that can produce the maximum benefits of fuel-treatment process which can give better combustion, maximum power with minimum noxious pollutants. The reformed fuel was obtained in the laboratory by special mixing process and the ignition study was conducted on the fuel. The ignition probability study is one of the methods used by researchers in United Kingdom to study the comparison of ignitability of fuels used in spark ignition engine. This preliminary study has been carried out, based on UK Emission Consortium Methods for High Tolerance EGR Combustion in the laboratory. The study has been carried out using fan-stirred bomb with various turbulent conditions. The study has shown that the reformed fuel-air has better ignition probability and can be ignited even at higher turbulent condition, compared to isooctane-air. The result has shown great potential of this system and encourage further fundamental research on the laminar burning velocity of reformed fuel which can be used to correlate to turbulent burning rate and therefore enhance the efficiency of combustion in spark ignition engines.
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7. Effect of Impeller Diameter to Vessel Diameter Ratio on Gas Holdup
Mohd. Sobri Takriff, W.R. Penney & J.B. FasanoAbstract
Numerous gas holdup correlations have been developed for predicting gas holdup in agitated vessels. However; gas holdup studies were only limited to the use of impeller diameter to vessel diameter ratio (Di/DT) of approximately 1/3. None of the available correlations considered the effect of (Di/DT) variation on gas holdup. This work was carried out to investigate this effect. The results of this investigation showed that the gas holdup increases with (Di/DT) ratio. The effect of (Di/DT) variation on gas holdup was correlated, with e = 2.0(NaNFr)O.6NRe 0.1 (Di/DT)2.5, for an air-water mixture. The (Di/DT) used in this work ranged from 0.36 to 0.53.
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8. IGBT Modelling using Hspice Curve-Fitting Optimisation Method
Norman Mariun, Ishak bin Aris, D. Liang & W. ShepherdAbstract
This paper presents the development of the IGBT model using the HSPICE package running on a Sun Workstation. The two important characteristics of an IGBT, which were considered in modelling the device, are the conduction (static) and the switching (dynamic) characteristics. The IGBT model proposed is discussed briefly to give background before a detailed development of the model is presented. The steps in modelling the IGBT using the curve-fitting optimisation method available within HSPICE are explained. The simulation results of varying the model parameters are discussed. On the basis of these results appropriate parameters for the IGBT model are determined for use in the curve-fitting optimisation method. Further, the test circuit simulation is presented to validate the static and dynamic parameters of the model chosen. The results are compared with manufacturer’s data sheet for the static parameter and laboratory test results for the dynamic parameters. The results are found to be in good agreement.
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9. The Effect of Design and Operating Parameters on the Flooding of a Gas-Liquid Mechanically-Agitated, Compartmented Column
Mohd. Sobri Takrif, W.R. Penny & J.B. FasanoAbstract
Column flooding for counter current flow of gas and liquid in compartmented columns was assumed not to be possible due to large density difference between the phases, however, experience at Chemineer Inc. shows otherwise. For this reason this work is carried out to investigate the flooding phenomena in an agitated-compartmented column. The effects of impeller speed, impeller diameter and liquid flow rate on column were investigated. Gas flooding velocity through the interstage opening was found to increase with impeller speed and decrease with liquid rate. The flooding velocity was observed to be higher for larger impeller at lower impeller tip speed. At higher impeller tip speed, the effect of impeller size on flooding velocity diminishes.
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10. Production of Bio-Oil From Palm Oil Shell
M.N. Islam & F.N. AniAbstract
Biomass in the form oil palm shell, an agro-industrial solid waste abundantly available in Malaysia was first pyrolysed followed by catalytic cracking in an integrated catalytic fast pyrolysis system. The pyrolysis process was carried out in afluidized-bed system while the catalytic treatment in afixedbed system. Tn the fluidized-bed silica sand was used as bed material while in the fixed-bed zeolites H-ZSM-5 and H-USY were used as catalysts. Nitrogen gas was used as the carrier gas. The fast pyrolysis was performed by feeding granulated raw materials directly into the hot fluid-bed at temperature ranging from 400 to 600°C. The maximum oil yield of 58 wt% was obtained at optimum temperature of 500°C with an apparent vapor residence time of 1.48 sec. The products obtained were liquid bio-oil, solid char, gases and coke. The variation of product yields and product compositions with catalytic bed temperature for catalysts H-ZSM-5 and H-USY were considered in the study. The liquid yield was found to be decreasing with the increase of catalytic reactor bed temperature while the gas and coke yields were increasing with catalytic bed temperature. The chemical compounds obtained were organic acids. phenols. hydrocarbons. alcohol. esters and ketones. Phenol is an important chemical with divergent application. For example. it can be used moulding products for automotive parts, household appliances. electrical component. adhesive resins for laminating. plywood. and insulating materials. On the other hand high hydrocarbon content indicates it can be used as raw fuel in automotive engines. All these are considered to be very high value chemicals from the point of view of value and price.
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