ADDRESS

Faculty of Engineering and Built Environment
Universiti Kebangsaan Malaysia

Volume 22 (2010)

Table of Contents

No. Article Detail
1. Komposit La1-xSrxCo1-yFeyO3-d (LSCF) sebagai Bahan Katod Tahan Lama bagi Sel Fuel Oksida Pejal Bersuhu Sederhana-Rendah: Ulasan Kajian (La1-xSrxCo1-yFeyO3-d (LSCF) Composite as Durable Cathode Materials for Intermediate-Low Temperature Solid Oxide Fuel Cell: Research Review)
Hamimah Abd. Rahman, Andanastuti Muchtar, Norhamidi Muhamad & Huda AbdullahAbstract
Solid oxide fuel cell (SOFC) is the most efficient fuel cell with the ability to directly convert chemical energy into electrical energy. Although there are numerous advantages offered by SOFCs, such as high energy conversion efficiency, low noise, less emission of pollutants and flexibility of hydrocarbon fuels, the processing cost and the performance improvement of SOFCs are hindered due to the higher operational temperatures. Therefore, the tendency to reduce the operational temperature of SOFC has brought about the development of research in materials and fabrication technology of fuel cells. Recently, among the many types of cathode materials that have been studied, lanthanum strontium cobalt ferrite, La1- x Srx Co1-yFey O3-d (LSCF) has been discovered to offer the most potential for use as cathode material in intermediate to low temperature SOFCs. The use of LSCF composite cathode has significantly reduced the cathode polarisation resistance and expanded the triple phase boundary (TPB) area available for oxygen reduction. The overall performance of cathodes and fuel cells are also influenced by the method of powder preparation and fabrication of the composite cathodes. As such, the present article focuses on the LSCF composites for use as durable cathode material in SOFCs from the aspects of materials development, powder preparation and fabrication techniques.
DOI : dx.doi.org/10.17576/jkukm-2010-22-01
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2. Perbandingan Ralat ‘Multipath’ bagi Data Cerapan GPS Stesen MASS dan Stesen RTK (Multipath Comparison for GPS Observation MASS Station Data and RTK Station)
Mardina Abdullah, Norbahiah Misran, Nor Nadira M. Ariff & M. Fazrin AbdullahAbstract
Multipath is one of the major sources of error in GPS code and carrier phase measurements that prevents the achievement of the highest levels of accuracy in GPS applications. Multipath occurs when signals travelling from a transmitter to a receiver propagate via multiple paths due to reflection and diffraction. The aim of this paper is to analyze the effect of multipath between MASS (Malaysia Active GPS System) station and GPS RTK (GPS Real Time Kinematic) reference station. The data is analysed from 15 MASS stations and 27 GPS RTK reference stations that are strategically located throughout Malaysia. This research also identifies which station between MASS station and GPS RTK reference stations are the most and least affected by multipath effect of both pseudo ranges at L1 (1575.42 MHz) and L2 (1227.60 MHz) of GPS signals. TEQC (Translating, Editing and Quality Checking) software is used to obtain multipath errors for both GPS signals. Based on the results, it is shown that the multipath error effects highly affect pseudo ranges for carrier frequency L2 more than the carrier frequency L1 which is consistent with previous research findings. It is shown that the most affected GPS data for multipath at L1 is from GPS RTK reference station and the least is from MASS station. The most affected at L2 is from MASS station and the least from GPS RTK reference station. For further research, more data are needed to be analyzed and better methods are required to analyze GPS data.
DOI : dx.doi.org/10.17576/jkukm-2010-22-02
download buttonPage 11-22
3. Jumlah Kandungan Elektron Sewaktu Gangguan Ionosfera Bergerak di Parit Raja, Johor (Total Electron Content During Travelling Ionospheric Disturbance in Parit Raja, Johor)
Mardina Abdullah, Dayang Azra Awang Mat, Ahmad Faizal Mohd Zain, Sabirin Abdullah, Asnawi Asnawi & Siti Sarah Nik ZulkifliAbstract
Travelling ionospheric disturbance (TID) is a phenomenon caused by solar activity and TID strength varies by locations, especially in equatorial regions. This phenomenon affects the local total electron content (TEC), especially during the daytime. Because of this, research regarding augmenting TEC values during TID is done by comparing TEC values obtained from the IRI2001 and NeQuick models with IONEX data. By using Global Positioning System (GPS) data obtained from the Parit Raja station in the southern part of Malaysia (1º 52’ N, 103º 06’ E) as reference, research was conducted during geomagnetic quiet day as well as on the disturbed day. The occurrence of TID can clearly be seen when using the real TEC data from IONEX and WARAS. Result obtained from Parit Raja station shows a much more significant effect of TID occurrence on TEC than what was shown by IONEX data. However, the TEC values obtained from the IRI2001 and NeQuick models were influenced by the number of sunspots and were only applicable in geomagnetic quiet days. In order to obtain more accurate TEC values, it is necessary to ensure that TID condition is included in the IRI2001 and NeQuick models.
DOI : dx.doi.org/10.17576/jkukm-2010-22-03
download buttonPage 23-30
4. Penentuan Ralat Multipath bagi Data Cerapan GPS Julat Pseudo di Stesen Rujukan RTK (Real Time Kinematic) di Malaysia (Multipath Error Determinant for Pseudo Ranges Observation Data at RTK (Real Time Kinematic) Reference Stations in Malaysia)
Mardina Abdullah, Norbahiah Misran & Nor Nadira Mohammad AriffAbstract
Multipath is widely recognized as one of the main source of error in GPS applications. Multipath is the phenomenon whereby a signal arrives at a receiver via multiple paths attributable to reflection and diffraction. This paper describes the analysis of multipath error of pseudorange obtain from RTK reference station. RTK reference station consists of 27 GPS reference stations and these stations are strategically distributed across Malaysia. This research also identifies which RTK reference station are the most and least affected by multipath effect of both pseudo ranges at L1 (1575.42 MHz) and L2 (1227.60 MHz) of GPS signals. In this research, TEQC software is used to check the multipath effect of both signals. It is shown that the most affected GPS data for multipath at L1 is from Marang (MARG) station with a value 0.453 m and the least from Kuala Kubu Baru (KKBH) station with a value 0.332 m. The most affected at L2 is also from MARG station 0.666 m and the least from Pekan (PEKN) station 0.431 m. It is hoped that this research be very helpful in GPS navigation.
DOI : dx.doi.org/10.17576/jkukm-2010-22-04
download buttonPage 31-42
5. Combustion Characteristics of Methane in A Direct Injection Engine Using Spark Plug Fuel Injector
Taib Iskandar MohamadAbstract
The combustion characteristics of methane in a direct injection spark ignition engine using Spark Plug Fuel Injector (SPFI) was investigated. SPFI is a system developed to convert any externally-mixing (port injection, carburetor) spark ignition engine to direct injection by combining fuel injectors into spark plugs. The burning rates of methane were measured using normalized combustion pressure method, where the normalized pressure rise due to combustion is equivalent to the mass fraction burnt at the specific crank angle. A single cylinder research engine was installed with the SPFI system. Cylinder pressures were taken with engine running at 1100 rpm and stoichiometric air/fuel ratio. The spark timing was set at 25o BTDC. For comparison, the engine was run with methane port injection. The optimal fuel injection timing with SPFI was found to be 170o BTDC. Results showed that SPFI direct injection, increased the volumetric efficiency by 11% compared to port injection, resulting in higher heating value of cylinder charge per cycle. Combustion analysis show that the overall burning rate of methane direct injection is faster than the ones of port injection although is slower at the initial stage. Injection pressures affect ignition delay but not the combustion duration. Changing mixture stoichiometry affects the magnitude of ignition delay. Combustion duration increases with leaner mixture. Different load conditions have significant effect on combustion process. Lower loads tend to increase combustion duration but shorten ignition delay. SPFI Di methane system has the potential of increasing engine performance due to increased volumetric efficiency and faster burning rate.
DOI : dx.doi.org/10.17576/jkukm-2010-22-05
download buttonPage 43-52
6. Kajian Prestasi dan Emisi Enjin Terhadap Kesan Asid Oliek Teroksida sebagai Bahan Tambah Bahan Api Petrol (Performace Test and Engine Emission on Acid Oleic Oxygenated as Additives Petrol)
Yusoff Ali, Abdul Amir Hassan Kadhum & Irfan WahyudiAbstract
The objective of this study is to investigate the effect of oxygenated oleic acid additives in standard petrol on the engine performance and the exhaust emissions. The 4-stroke 1.5 litre engine was used on the engine test bed coupled to eddy current electric dynamometer which is also connected to CADET V12 control system and exhaust gas analyser IMR 2000/2000P. The oxygenated oleic acid additives used for this experiment is fixed at 0.2% by volume due to limited quantity available. Two types of test were carried out first test is with variable speed and no loads and the second test is at constant speed of 1,400 rpm with variable loads. The experimental results showed that the brake power increased by 2%, torque by 2%, brake thermal efficiency by about 7% and specific fuel consumption decreased by about 10%. The exhaust emissions analysed are carbon monoxide, (CO), carbon dioxide (CO2 ) and oxides of nitrogen (NOx ). The result by comparing the oxygenated petrol with the standard petrol indicated that CO gas emission depend on the engine speed which decreased with increasing speed up to 1,600 rpm and increased after that speed on test without load. The CO also decreased by about 28% on the test with loads. The emission of CO2 increased by 2.7% for tests with load and by 8% for tests without loads. The NOx emission decreased by 9% for test without load and about 7% for test with load. This study indicates that engine performance is improved by adding 0.2% oxygenated additives to standard petrol.
DOI : dx.doi.org/10.17576/jkukm-2010-22-06
download buttonPage 53-62
7. Penggunaan Kaedah Algoritma Genetik dalam Permasalahan Penjadualan PCB: Kajian Kes di Industri Elektronik (The Use of Genetic Algorithm in PCB Scheduling Problem: Case Study in Electronic Industry)
Zalinda OthmanAbstract
Production planning and scheduling functions play important roles in production especially to ensure the availability of manufacturing resources needed to accomplish production tasks. This paper proposes the use of Genetic Algorithm in solving scheduling problems and the case study has been conducted in printed circuit board assembly company. Genetic algorithm formulation included chromosome representations and genetic operators have been developed to suit the scheduling problems that take into account the alternative production lines. Simulation results have been compared to the manual schedules. It shown that the genetic algorithm is capable to produce schedules with shorter assembly time. It is can accommodate additional elements such as maintainance time quite easily. This is done by adding the maintenance time slot within the chromosome. Another experiment has been done by using dispatching rule in sequencing the models on the assembly lines. Genetic Algorithms have shown a promising results compared to manuan and dispatching rule.
DOI : dx.doi.org/10.17576/jkukm-2010-22-07
download buttonPage 63-74
8. Penilaian Model Empirik Keupayaan Galas Tanah Baki Sedimen daripada Kaedah Gelombang Permukaan (Empirical Model Evaluation of Sedimentary Residual Soil Bearing Capacity from Surface Wave Method)
Sri Atmaja Rosyidi, Mohd. Raihan Taha, Khairul Anuar Mohd NayanAbstract
Bearing capacity of the subgrade layers has significant influence on the performance of the overall pavement structure. In this study, the Spectral Analysis of Surface Wave (SASW) method was used for assessing the stiffness of pavement subgrade layer. The SASW method employed was based on the Rayleigh-wave propagation. Using the phase difference data of Rayleigh waves, the experimental dispersion curve of phase velocity was obtained. Consequently, inversion process was conducted to obtain the shear wave velocity and the dynamic modulus of the pavement structure. The results showed that some empirical models of the shear wave velocity and the dyamic elastic modulus versus soil bearing capacity of the California bearing ratio (CBR) and dynamic cone penetrometer (DCP) were derived. Good agreement was also found between these empirical models compared to that of previous studies.
DOI : dx.doi.org/10.17576/jkukm-2010-22-08
download buttonPage 75-88
9. Consolidation Behaviour of The Neutralisation Spent Pickle Liquor (NSPL) Sludge from Steel Works
N. N. Nik Daud, H. R. Thomas & S. SeetharamAbstract
The disposal of industrial waste sludge at a landfill has become a global problem especially when dealing with high moisture content material. Neutralisation Spent Pickle Liquor (NSPL) sludge waste generated in steel industry has been categorized as one of the slurry wastes in geotechnical engineering and poses serious handling problem due to its high water content. The NSPL sludge waste is categorized as a high water content material with a low solid concentration.The main objective in this paper is present a study related to compressive behaviour of the NSPL sludge material under external load. A series of consolidation tests of different NSPL initial water content and load pressure using Rowe cell equipment were performed. The consolidation behaviour of the NSPL sludge was shown to be complex, especially during the initial stages of the loading process. For any given load increment, an instantaneous compression was observed but no pore water dissipation were detected. The coefficient of permeability was found to be very high during the first few minutes, i.e. in the range of 10-4 – 10-5 m/s, and reduces significantly to 10-10 m/s after the first 17 hours of the test. The compression behaviour of the sludge materials are directly related to their coefficient of permeability.
DOI : dx.doi.org/10.17576/jkukm-2010-22-09
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10. Pengaruh Gandaan EDFA Terhadap Prestasi Rangkaian Cincin Metropolitan (EDFA Gain Influence towards Metropolitan Ring Network Performance)
Mohammad Syuhaimi Ab-Rahman, Iskandar Yahya, Suliana Sulaiman, Sahbudin Shaari & Kasmiran JumariAbstract
The main objective of the simulatin study is to observe the effect of gain profil for pre-amplifier and post amplifier to the output power and bit error rate (BER) performance in 600 parameter metropolitan ring network. Four profil have been introduced (A, B, C and D) and the effect of the gain value can be seen through the maximum achievable node. The study focuses also the effect of pre-amplifier on the exciting point in evaluation the BER performance. The outcomes of this study is to acquire the ideal gain value for pre and post amplifier in Optical Cross Add and Drop Multiplexer (OADM) metropolitan ring network. The Opti_System simulation is used to achieve the objectives as mentioned earlier.
DOI : dx.doi.org/10.17576/jkukm-2010-22-10
download buttonPage 97-106
11. Rekabentuk Peranti Pencerai Optik Pelbagai Nisbah (MROS) Berasaskan Pandu Gelombang Planar untuk Penggunaan Kuasa Berkesan (The Design Multi Ratio Optical Splitter (MROS) based on Plannar Waveguide for an Effective Power Usage)
Mohammad Syuhaimi Ab-Rahman, Norazilawati Md Zain & Aida BaharudinAbstract
In this paper, we present the design of Multi Ratio Optical Splitter (MROS) based on planar waveguide with SU-8 polymer material. The technology ensures low cost fabrication and excellent performance as compared to conventional technique that uses fused coupler for optical splitter fabrication. The MROS is suggested to be used in passive customer access network FTTH-PON in power management in maximizing the consumption. With this, the distance can be extended as compare to the theoretical distance (20 km). It is the first time reported. The problems arose such as the loss of output power is also discussed. The simulation result shows that various factors; namely the width of waveguide, refractive index and wide-angle branching will increase the output power loss. To obtain maximum power, the optimization of those parameters’ value must be used. This designed optical splitter is operated at wavelength 1500 nm – 1600 nm. In this study, we characterized the trend of total output power with the effect of the parameters studied.
DOI : dx.doi.org/10.17576/jkukm-2010-22-11
download buttonPage 103-117