Kuala Lumpur, Malaysia
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Teh G.B.,Tunku Abdul Rahman College | Wong Y.C.,Swinburne University of Technology | Wang J.,Swinburne University of Technology | Tan S.G.,University Tunku Abdul Rahman | Samini B.,University Tunku Abdul Rahman
Materials Science Forum | Year: 2010

Magnetoplumbite-type (M-type) strontium ferrite particles with two stoichiometric ratios (SrFexO19; x = 9.2 and 11.6) have been synthesized via the sol-gel technique employing ethylene glycol as the gel precursor. The prepared samples were characterized using x-ray diffractometry (XRD), thermogravimetric analysis (TGA), photoluminescence (PL) spectrophotometry, field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectrometry (EDS) and superconductivity quantum interference device magnetometry (SQUID). X-ray powder diffraction patterns showed that the samples were single-phase with the space group of P63/mmc and cell parameter values of a = 5.88 Å and c = 23.03 - 23.04 Å. EDS results confirmed the composition being mainly of M-type SrFe12O 19. The photoluminescence property of strontium ferrite was examined at excitation wavelength of 260 - 290 nm and significant PL emission peaks centered at 334 nm were detected. Both as-prepared strontium ferrites exhibited significant oxygen vacancies which were detectable via TGA where the sample with the Sr/Fe ratio of 1:11.6 exhibited the highest oxygen vacancies in its structure. © (2010) Trans Tech Publications.

Teh G.B.,Tunku Abdul Rahman College | Wong Y.C.,Swinburne University of Technology | Tilley R.D.,MacDiarmid Institute for Advanced Materials and Nanotechnology
Journal of Magnetism and Magnetic Materials | Year: 2011

Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 °C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device magnetometer. XRD results showed that the sample synthesized at 1000 °C was of single-phase with a space group of P63/mmc and lattice cell parameter values of a=5.882 Å and c=23.048 Å. EDS confirmed the composition of strontium ferrite calcined at 1000 °C being mainly of M-type SrFe12O19 with HRTEM micrographs confirming the ferrites exhibiting M-type long range ordering along the c-axis of the crystal structure. The photoluminescence (PL) property of strontium ferrite was examined at excitation wavelengths of 260 and 270 nm with significant PL emission peaks centered at 350 nm being detected. Strontium ferrite annealed at higher temperature (1000 °C) was found to have grown into larger particle size, having higher content of oxygen vacancies and exhibited 8385% more intense PL. Both the as-prepared strontium ferrites exhibited significant oxygen vacancies defect structures, which were verified via TGA. Higher calcination temperature turned strontium ferrite into a softer ferrite. © 2011 Elsevier B.V. All rights reserved.

Yip M.W.,Tunku Abdul Rahman College | Barnes S.,University of Warwick
Advanced Materials Research | Year: 2013

The objective of this research was to develop a new form of clad layer by producing a Silicon Carbide (SiC) particle reinforce Metal Matrix Composite (MMC) using the iron based alloys as the matrix material. A 1.2kW continuous wave CO2 laser was used in this research. A gravity feed system was used with one powder feed which contained different percentages of SiC particles and iron based powder. Experimental results showed that the decomposition of SiC particles was observed and only a few SiC particles were found in the clad matrix. High micro hardness values were found in the SiC clad which were in excess of 1000 HV. However, most of the SiC were evaporated which created porosity in the melt pool. Therefore, blown powder technique is recommended for overcome this problem. © (2013) Trans Tech Publications, Switzerland.

Ooi J.,Tunku Abdul Rahman College | Wang X.,University Tunku Abdul Rahman | Lim Y.P.,University Tunku Abdul Rahman
50th Annual Conference of the British Institute of Non-Destructive Testing 2011, NDT 2011 Held in conjunction with the Materials Testing Exhibition, MT 2011 | Year: 2011

Portal axle unit is a gearbox unit installed on every end axles of the vehicle. They are installed to the vehicle to give higher ground clearance to enable vehicle to go over large obstacle when driving in off-road conditions. Shafts designed must be exceptionally tough and lightweight to improve the overall performance of the portal axle unit. In this paper, the design of the hollow shaft with rib attached at each end is analysed in detail. Selected parameters of the rib are studied to further optimize the proposed shaft design. Finite element method (FEM) is employed to simulate stress analysis on the shaft models. Torque delivered from the engine to the shaft and the shaft's weight is considered in the FEM simulation. The stress and weight reduction results are calculated for optimum shaft, existing shaft and solid shaft for comparison. The optimum model of the shaft shows slight improvement over the existing shaft. © (2011) by the British Institute of Non-Destructive Testing. All rights reserved.

Lim Y.S.,University Tunku Abdul Rahman | Lo C.K.,University Tunku Abdul Rahman | Teh G.B.,Tunku Abdul Rahman College
Renewable Energy | Year: 2012

The Luminescent Solar Concentrator (LSC) is a polymer plate that contains a luminescent specimen with photovoltaic (PV) cells attached to its edges. Light entering on the plate is absorbed by the luminescent material which in turn emits light. Part of the emitted light propagates through the plate and arrives at the PV cells through the total internal reflection. The ratio of the area of the relatively cheap polymer plate to that of the expensive PV cells is increased. At present, PMMA (poly(methyl methacrylate)) is the preferred host matrix for LSCs due to its satisfactory optical clarity, refractive index, photo-stability and mechanical resistance. In order to maximize the benefits of using LSCs, this paper proposes an alternative host matrix made of unsaturated polyester (UP). An appropriate amount of MMA is used in producing LSCs in order to enhance the optical transparency and refractive index of LSCs. The cost of such LSCs is lower than that of PMMA. © 2012 Elsevier Ltd.

Wong J.E.,Physical Activity and Energy Metabolism Research Group | Poh B.K.,Physical Activity and Energy Metabolism Research Group | Nik Shanita S.,Physical Activity and Energy Metabolism Research Group | Izham M.M.,Physical Activity and Energy Metabolism Research Group | And 4 more authors.
Singapore Medical Journal | Year: 2012

Introduction This study aimed to measure the basal metabolic rate (BMR) of elite athletes and develop a genderspecific predictive equation to estimate their energy requirements. Method s 92 men and 33 women (aged 18-31 years) from 15 sports, who had been training six hours daily for at least one year, were included in the study. Body composition was measured using the bioimpedance technique, and BMR by indirect calorimetry. The differences between measured and estimated BMR using various predictive equations were calculated. The novel equation derived from stepwise multiple regression was evaluated using Bland and Altman analysis. Results The predictive equations of Cunningham and the Food and Agriculture Organization/World Health Organization/United Nations University either over- or underestimated the measured BMR by up to ± 6%, while the equations of Ismail et al, developed from the local non-athletic population, underestimated the measured BMR by 14%. The novel predictive equation for the BMR of athletes was BMR (kcal/day) = 669 + 13 (weight in kg) + 192 (gender: 1 for men and 0 for women) (R2 0.548; standard error of estimates 163 kcal). Predicted BMRs of elite athletes by this equation were within 1.2% ± 9.5% of the measured BMR values. Conclusion The novel predictive equation presented in this study can be used to calculate BMR for adult Malaysian elite athletes. Further studies may be required to validate its predictive capabilities for other sports, nationalities and age groups.

Kuik S.S.,University of South Australia | Nagalingam S.V.,University of South Australia | Amer Y.,University of South Australia | Saw Y.P.,Tunku Abdul Rahman College
SCMIS 2010 - Proceedings of 2010 8th International Conference on Supply Chain Management and Information Systems: Logistics Systems and Engineering | Year: 2010

Six Sigma has been a prevailing methodology used by numerous sectors of manufacturing organisation around the world. Six Sigma is also considered as a business management strategy and a well-structured approach to reduce process variation and waste. However, there is a limited empirical analysis on implementing Six Sigma approaches within a global supply chain network in a developing country as well as addressing the practical issues encountered by these foreign manufacturing investors. This paper aims to address these gaps by intensively analysing Six Sigma implementation strategy and providing an overview status of the implementation of Six Sigma approaches within a global supply chain network in a developing country, i.e. Malaysia through the pilot results obtained by a co-author. In order to be successful in a highly competitive market, many industrial partners need to collaborate in a global supply chain network to produce high quality products and increase competitive advantage. Hence, a generic guideline based on Porter's model for foreign manufacturing investors is proposed in this paper to ease the implementation of Six Sigma to improve supply chain networks.

You K.Y.,University of Technology Malaysia | Lee C.Y.,University of Technology Malaysia | Then Y.L.,University of Technology Malaysia | Chong S.H.C.,Tunku Abdul Rahman College | And 3 more authors.
IEEE Sensors Journal | Year: 2013

A handheld microwave reflectometer-sensor system is developed to operate from 1.35 to 1.95 GHz and used to measure volumetric and gravimetric moisture content in various types of soils from 0% to 45%. A small monopole driver from coaxial line is buried into the soil, and its reflected voltage is measured and correlated with corresponding soil moisture content obtained from oven dying method. The measured reflected voltage is dependent on the nonlinear change of dielectric properties of the soil with the moisture content. © 2001-2012 IEEE.

Ting T.O.,Xi'an Jiaotong - Liverpool University | Ting H.C.,Tunku Abdul Rahman College | Lee S.,Xi'an Jiaotong - Liverpool University
Lecture Notes in Electrical Engineering | Year: 2013

This paper proposes an effective Segregated Lightweight Dynamic Rate Control Scheme (SLDRCS) over the internet. Based on the feedback analysis of the current approaches, we found that the indicator of the congestion is only the queue length. It only captures a partial indicator of delay and loss in feedback mechanism. This may result in an ineffective way in controlling the network when congestion control occurs. Therefore, we suggest multiple congestion indicators to adapt inside this scheme to fully control the average delay and loss from bidirectional of sender to receiver. The behavior of next event packet being control using discrete event simulation tool with First Come First Serve (FCFS) scheduling policy and we code this algorithm into C programming language. Through the simulation results, our Segregated Lightweight Dynamic Rate Control Scheme (SLDRCS) guaranteed high improvement in packet drop and average delay under various congestion level and traffic load conditions compare with the current approach. © 2013 Springer Science+Business Media Dordrecht.

Wei C.K.,Tunku Abdul Rahman College | Fung L.C.,Tunku Abdul Rahman College | Pang M.,Tunku Abdul Rahman College
Malaysian Journal of Analytical Sciences | Year: 2011

Studies on determination of six kinds of phthalates, i.e. dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP), in three kinds of plastic containers for food use, including food container, instant noodle cup and snack container, by gas chromatography in combination with mass spectrometry detector (GC-MS) in electronic ionization mode with selected-ion monitoring (SIM) acquisition method (GC-MS(EI-SIM)) have been carried out. Extraction, clean-up and analysis methods have been developed and optimized. Determination of samples were performed after sonication-assisted extraction with 1:9 toluene and dichloromethane, clean-up with Bio-Beads S-X8 gel-permeation column and analyzed by GC-MS methods. The characteristic ions, 163, 194 for DMP; 149, 177, 222 for DEP; 149, 233, 251 for DBP; 91, 149, 206 for BBP; 149, 176, 193 for DEHP; 149, 167, 279 for DNOP were chosen for quantitative studies. These techniques are possible to detect phthalates at the level of 1-70 mg/kg. The overall recoveries were 79.2-91.1% with relative standard deviation (R.S.D.) values at 3.1-11.3%. Only DEHP was detected in the studied samples.

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