Displaying publications 1 - 20 of 173 in total

Abstract:
Sort:
  1. Harun, S.W., Tamjis, M.R., Muhd-Yassin, S.Z., Abd-Rahman, M.K., Ahmad, H.
    ASM Science Journal, 2007;1(2):129-133.
    MyJurnal
    This paper demonstrates an erbium/ytterbium co-doped fi bre amplifi er (EYDFA) which used a pumping wavelength of 1058 nm, whereby the amplifi cation was assisted by the energy transfer between Yb and Er ions. The energy transfer increased the erbium doping concentration limit that was imposed by concentration quenching in erbium-doped fi bre. The optimum length was obtained at 4m~6m for erbium/ytterbium co-doped fi bre with Er ion concentration of 1000 p.p.m. This enabled the development of a compact amplifi er with a shorter gain medium compared to erbium-doped fi bre amplifi ers which use a gain medium of up to 15 m. A 1058 nm pumping wave-length was used for the EYDFA, as 1480 nm pumping resulted in severely degraded gain and noise fi gures because the energy transfer could not be achieved. The use of the optical isolator improved the small signal gain and noise fi gure by about 4.8 dB and 1.6 dB, respectively. Without the isolator, gain saturation and a noise fi gure penalty were observed due to the oscillating laser which was created at around 1534 nm by spurious refl ection. This showed that the usage of optical isolators was an important aspect to consider when designing an EYDFA.
  2. Ismail, A.
    ASM Science Journal, 2007;1(2):169-175.
    MyJurnal
    As we move towards the knowledge (K) era, the challenge in R&D is to focus on the development of original K-based products that can compete in the global market. The development of commercially viable, patented K-based products within a university environment require an innovation system and innovation policies in place and a change in the paradigm towards the approach to research. A crucial agent towards the success of the innovation system is development and training of the human capital that would be the future drivers of the K-industry. Awareness of intellectual property rights, the need for original research, entrepreneurship as well as the development and strengthening of self-confidence and leadership are among the factors needed towards the training of K-workers facing the new economy.
  3. Jesudason, C.G.
    ASM Science Journal, 2007;1(1):7-18.
    MyJurnal
    Molecular dynamics reaction simulation showed that the rate constant is not constant over the concentration profile of reactants and products over a fixed temperature regime, and this variation is expressed in terms of the defined reactivity coefficients. The ratio of these coefficients for the forward and backward reactions were found to equal that of the activity coefficient ratio for the product and reactant species. A theory was developed to explain kinetics in general based on these observations. Several other theorems had first to be developed, most striking of all was the inference that the excess Helmholtz free energy was the thermodynamical function which had a direct relation to these activity factors than the Gibbs free energy. The theory is applied to a class of ionic reactions which could not be rationalized using the standard Bjørn-Bjerrum theory of ionic reactions.
  4. Lashgari, V.A., Yoozbashizadeh, H.
    ASM Science Journal, 2007;1(1):37-41.
    MyJurnal
    Silicon, as the most important electronic material, has a lot of applications in the electronic industry and this includes the use of silicon in solar cells. One of the solar grade silicon production processes is the use of acid leaching for the removal of metallic impurities from silicon. The main advantage of this process for silicon purification is that it is based on a low temperature process. The purification of metallurgical grade silicon by acid leaching was studied as a function of time, temperature and etching. Based upon experimental results and under optimum conditions, it was possible to remove 41%, 71% and 25% of iron, calcium and aluminum respectively, with the use of aqua regia.
  5. Mahmood, A.A., Sidik, K., Fouad, H.M.
    ASM Science Journal, 2007;1(1):1-6.
    MyJurnal
    Ocimum basilicum seed extracts were found to possess significant anti-ulcer activity against ethanol-induced ulceration in experimental animal models. Three groups of adult male rats were used, with each group consisting of six rats. Oral administration of absolute ethanol to rats pre-treated with 10% Tween 20® (Group 1) produced extensive haemorrhagic lesions of the gastric mucosa. Rats orally pre-treated with O. basilicum extract suspended in 10% Tween 20® (Group 2) or cimetidine in 10% Tween 20® (Group 3), 30 min before oral administration of absolute alcohol had significantly reduced (p
  6. Khalijah, M.S., Helmy, M.H.M.
    ASM Science Journal, 2007;1(2):177-180.
    MyJurnal
    The Ministry of Science Technology and Innovation (MOSTI) Angkasawan (Astronaut) Programme achieved its mission to send the first Malaysian astronaut Sheikh Muszaphar Shukur by Soyuz TM11 to the International Space Ship (ISS) on 10 October 2007. He returned to earth, landing safely on 21 October 2007. Such a momentous event has carved out yet another milestone in the country’s
    history and development of a civilisation based on science and technology for its people. This mission has provided the educational sector with an opportunity to initiate a curriculum innovation. Together with the Ministry of Education (MOE), the initiative was undertaken to improve techniques of teaching and learning (TL) and to broaden its scope to include space science and technology.
  7. Leman, Z., Ismail, N., Tai, S.S., Sapuan, S.M.
    ASM Science Journal, 2007;1(2):135-141.
    MyJurnal
    All relevant and essential data of an existing vehicle seat assembly line such as the operating time and processes, material handling system, workstation layout, bill of materials, equipment and hand tools, were collected and analyzed. The time standards for each of the vehicle seat assembly elements were established using work study techniques. A simulation approach was used to determine the productivity and effi ciency of the existing and proposed lines. Simulation technique was also used to determine and identify bottle-necks in both existing and proposed systems. Comparison of the existing assembly line and the proposed assembly line in terms of their productivity and effi ciency are also highlighted.
  8. Othman, M., Ahmad, K.
    ASM Science Journal, 2007;1(2):181-182.
    MyJurnal
    Comet 17P/Holmes was discovered by Edwin Holmes on 6 November 1892 while he was conducting regular observations of the Andromeda Galaxy (M31). Calculations using observation of its orbits established the perihelion date as 13 June and the orbital period as 6.9 years. The 1899 and 1906 appearances were observed, but the comet was only seen again in 1964. The comet has since been
    observed on every subsequent return.
  9. Arifin, N.M., Mokhtar, N.F.M., Nazar, R., Pop, I.
    ASM Science Journal, 2007;1(1):57-62.
    MyJurnal
    Linear stability analysis was used to investigate the onset of Marangoni convection in a two-layer system. The system comprised a saturated porous layer over which was a layer of the same fluid. The fluid was heated from below and the upper free surface was deformable. At the interface between the fluid and the porous layer, the Beavers-Joseph slip condition was used and in the porous medium the Darcy law was employed to describe the flow. Predictions for the onset of convection were obtained from the analysis by the perturbation technique. The effect of surface deformation and depth ratio, z (which is equal to the depth of the fluid layer/depth of the porous layer) on the onset of fluid motion was studied in detail.
  10. Devendra, C.
    ASM Science Journal, 2007;1(1):63-73.
    MyJurnal
    The increased human demand for animal proteins in Malaysia is led by several factors: population growth, urbanisation, income growth and changing consumer preferences. Meeting the projected increased demand in the future is an awesome and challenging task. Presently, the non-ruminant poultry and pig industries, mainly private sector led, make the most significant contribution to total animal protein supplies, and inefficient ruminant production systems lag well behind. The strategy for promoting productivity growth to increase animal protein supplies from ruminants requires concerted efficient natural resource management that can target specific production systems. Two distinct economic opportunities are the development of oil palm-based cattle and goat production. The value addition to oil palm cultivation due to the beneficial crop-animal-soil interactions are enormous. The prerequisites are inter-disciplinary efforts, holistic systems, participatory community-based research and development that are needs-based and address constraints, increased research investments, institutional commitment and a policy environment that can enhance total factor productivity in the future.
  11. Sharif, J.M., Latiff, M.S.A., Ngadi, M.A.
    ASM Science Journal, 2007;1(2):109-128.
    MyJurnal
    Spatio-temporal datasets are a collection of datasets where data can vary in both space and time. Theoretically, such datasets can be considered as continuous and discrete. For example, specification of the function, F: Ed  T Rn, where Ed denotes d-dimensional Euclidean space, T = R* ∩ {} the domain of time and Rn an n-dimensional scalar field. Examples of such data sets include time-varying simulation results, film and videos, time-varying medical datasets, geometry models with motion or deformation, meteorological measurements, and many more. It is therefore highly desirable to use visualisation to summarize meaningful information in higher dimensional spatio-temporal datasets. Our aim is to conceive an efficient visual study to facilitate scientists in identifying temporal association among complex and chaotic atom movements in ion trajectories. An application that uses a streamline for spatial motion of ion trajectories and Colour Number Coding Scheme for temporal encoding of high degree of timeline events among mobile ions is proposed. With an anthology of the visual examples, it was revealed that this application would be beneficial for scientists to visually mine any 3D spatio-temporal dataset.
  12. Abdul Rahim, R., Pang, J.F., Chan, K.S., Leong, L.C., Fazalul Rahiman, M.H.
    ASM Science Journal, 2007;1(1):27-36.
    MyJurnal
    In this study, real-time imaging was monitored for flowing solid particles when various baffles were created to block certain areas of the pipe. The generated flow regimes were full-flow, three-quarter-flow, half-flow and quarter-flow. A vertical pneumatic conveyor was designed to hold a 85 mm inner diameter pipeline. The four projection optical tomography systems used, applied the parallel beam projection approach and use infrared light sources so that the sensor was free of noise from the surrounding visible light source. The two orthogonal and two rectilinear projections were axial, but ideally they should have been in the same layer. The sensor readings could be related to the varying light intensity effects of the dropping particles and were used to provide cross-sectional distribution information for the conveyor. By using computer programming, the information was reconstructed to produce coloured images and concentration was obtained by reference to a colour code. The results obtained from this study showed how imaged flow followed the artificial flow regime. This study could benefit industrial production lines in maintaining the desired flow rates.
  13. Kamal, Z.Z., Daud, A.H.M., Ashidi, M.I.N., Fadel, J.K.M.
    ASM Science Journal, 2007;1(2):87-100.
    MyJurnal
    Covering as much as 25% to 35% of the development cost, software testing is an integral part of the software development lifecycle. Despite its importance, the current software testing practice is still based on highly manual processes from the generation of test cases (i.e. from specifications) up to the actual execution of the test. These manually generated tests are sometimes executed using ad hoc approaches, typically requiring the construction of a test driver for the particular application under test. In addition, test engineers are also under pressure to test increasing lines of code in order to meet market demands for more software functionalities. While there are significant proliferations of helpful testing tools or research prototypes in the market, much of them do not adequately provide the right level of abstraction and automation as required by test engineers. In order to facilitate and address some of the aforementioned issues, an automated testing tool was developed, called SFIT, based on Java® technology. This paper describes the development, implementation and evaluation of SFIT. Two case studies involving the robustness assessment of an adder module and a Linda-based distributed shared memory implementation are described in order to demonstrate the applicability of SFIT as a helpful automated testing tool.
  14. Kassim, K.M., Davarnejad, R.
    ASM Science Journal, 2007;1(2):143-154.
    MyJurnal
    The objective of this paper is to model the extraction of carotenoid with supercritical carbon dioxide as the solvent. Experimental data for the high pressure vapour-liquid phase equilibrium of the binary system carbon dioxide-carotenoid was reviewed for the elevated temperatures of 313.15, 323.15, 333.15 K and pressures up to 500 bar. The experimental data was correlated and modeled using Redlich-Kwong equation of state and regular solution methods. The use of the equation of state as an empirical correlation for collating and predicting liquid-liquid and liquid-dense fluid equilibria is discussed. It was concluded that the estimation of some of the parameters required for these calculations would be difficult if the solute (carotenoid) was a complex substance about which little was known apart from its structural formula. An alternative procedure is to apply activity coefficient expression of the regular solution theory type to each phase. Calculations along these lines are described and the physical basis for applying these methods under the relevant conditions is discussed. The regular solution theory approach in particular was found to be encouraging for the mutual miscibility calculations for heavy components (such as carotenoid) particularly for substances sensitive to temperature, though the interaction parameters for he prediction activity coefficients must be regarded as pressure dependent.
  15. Sharifah, S.Y., Norsheila, F., Muladi
    ASM Science Journal, 2007;1(1):19-25.
    MyJurnal
    Orthogonal Frequency Division Multiplexing (OFDM) is a successful technique in wireless communication systems. Frequency offset in the OFDM system leads to loss of orthogonality among subcarriers which results in the occurrence of intercarrier interference (ICI). To improve the efficiency of bandwidth performance in the ICI self-cancellation scheme, frequency domain partial response signaling (PRS) was investigated. In this study, the integer polynomial partial response coefficients were exploited to enhance carrier-to-interference power ratio (CIR) in the OFDM system. CIR was enhanced up to 4.1 dB to 5 dB when the lengths of PRS polynomial, K was 2 and 5, respectively.
  16. Al-Mansoori, M.H., Mahdi, M.A., Iqbal, S.J., Abdullah, M.K.
    ASM Science Journal, 2008;2(2):107-113.
    MyJurnal
    In this paper, the tuning range characteristics of a multiwavelength L-band Brillouin-erbium fibre laser utilizing a linear cavity is described. The dependency of the Stokes signal tuning range on the laser’s pumping power and single mode fibre length is elaborated. The proposed laser configuration exhibited a wide tuning range of 11 nm from 1599 nm to 1610 nm. The maximum number of 28 output channels with a spacing of 10.5 GHz was achieved by setting the Brillouin pump wavelength and power at 1603.1 nm and 1.1 mW, respectively. The wider tuning range and higher number of Brillouin Stokes contributed to the higher efficiency of doublepass amplification in the erbium gain medium and also to the bidirectional generation of Brillouin Stokes in the single-mode fibre.
  17. Bidin, N.
    ASM Science Journal, 2008;2(2):179-182.
    MyJurnal
    The laser technology laboratory (LTL) of the Physics Department, University of Technology Malaysia was established in 1989 to support research and development activities. The laboratory provides activities for short- and long-term projects to serve final year undergraduate and post-graduate students in masters and PhD programmes.
  18. Shaari, S., Ehsan, A.A., Abd-Rahman, M.K.
    ASM Science Journal, 2008;2(2):153-161.
    MyJurnal
    An optical code generating device for a portable optical access-card system was constructed using the plastic optical fibre (POF) waveguide coupler. The newly constructed device provided output light intensities which were used as optical codes in a portable optical access-card system. The construction of a basic 1 × 2 waveguide design combined two major components which were the asymmetric Y-junction splitter and the linear taper. A hollow waveguide structure was utilized as it provided more flexibility in guiding light rays. A basic 1 × 2 waveguide coupler was designed using the CAD tool and then the ray was traced using the non-sequential ray tracing tool. A linear relationship between the tap-off ratio and the waveguide tap-width enabled a higher-level hollow waveguide coupler to be designed using the simple cascading technique. Construction of a 1 × 4 and higher level waveguide coupler was easily realized using the basic 1 × 2 waveguide coupler design together with a simple cascading technique.
  19. Abdul-Rashid, H.A., Al-Qdah, M.T., Chuah, H.T., Tayahi, M.
    ASM Science Journal, 2008;2(2):129-132.
    MyJurnal
    The operating principle and the performance of chromatic dispersion (CD) measurement technique are discussed through developed numerical models. The performance of the CD measurement technique was studied in terms of the measurement range and sensitivity as the wavelength separation was varied. Based on the numerical model, the technique sensitivity increased with wavelength separation. However, this increase in sensitivity was traded off with a narrower measurement range. The measurement technique was optimized at 5.0 GHz wavelength separation with a sensitivity of 0.009 (dB/ps/nm) and measurement range of 2500 ps/nm.
  20. Kandasamy, R., Azme, Hashim, I., Ismoen, M.
    ASM Science Journal, 2008;2(1):23-33.
    MyJurnal
    The effect of chemical reaction and variable viscosity on mixed convection heat and mass transfer for Hiemenz flow over a porous wedge plate was studied in the presence of heat radiation. The wall of the wedge was embedded in a uniform Darcian porous medium to allow for possible fluid wall suction or injection and had a power-law variation of both the wall temperature and concentration. The fluid was assumed to be viscous and incompressible. Numerical calculations were carried out for different values of dimensionless parameters and an analysis of the results obtained showed that the flow field was influenced appreciably by the buoyancy ratio between species, thermal diffusion and suction/injection at wall surface. The effects of these major parameters on the transport behaviours were investigated methodically and typical results illustrated to reveal the tendency of the solutions. Representative results are presented for the velocity, temperature, and concentration distributions. Comparisons with previously published works were performed and excellent agreement between the results were obtained. It is predicted that this research might prove to be useful for study of the movement of oil or gas and water through the reservoir of an oil or gas field, in the migration of underground water, in filtration, and water purification processes.
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links