Displaying publications 41 - 60 of 173 in total

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  1. 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.
  2. Devendra, C.
    ASM Science Journal, 2015;9(1):1-20.
    MyJurnal
    The natural environment embraces agriculture and all its components-crops, animals, land, water,
    forestry and fisheries. It is the most important user of environmental resources, made more complex
    by the interactions of the various systems, biophysical elements and their implications. Increased food
    production, especially of animal protein supplies are unable to meet current and projected future needs
    for humans, including about 15 %of the world population being malnourished. Agriculture is currently
    waning, and a coordinated and concerted technologically-driven transformation is necessary. Poorly
    managed agriculture for example, can lead to serious environmental degradation and exacerbate
    poverty. Land and water are considered to be the most limiting factors in the future. Non- irrigated
    rainfed areas can be divided into high potential and low potential areas; the former offers considerable
    promise to expand food production. This paper argues for increased Research and Development (R&D)
    focus that can maximise improved natural resource management(NRM), and whether agricultural
    development can maximise productivity yields .Other opportunities include expanding crop–animal
    production systems in less favoured areas (LFAs), intensifying land use for silvopastoral systems in
    rainfed areas , and enhance carbon sequestration. Ruminants can be used as an entry point for the
    development of LFAs, and the presence of about 41.5% of the goat population found in the semi-arid/
    arid AEZs X provides good opportunities for expanding food security and human well-being. Communitybased
    interdisciplinary and systems approaches are essential to provide the solutions. The legacy of
    continuing malnutrition and food insecurity must be overcome by effective development policy, multidonor
    resource allocation, governance and political will that target food insecurity and poverty. The R&D
    agendas and resource allocations are compelling, but dedicated vision can lead the way for sciencedriven
    sustainable environment, efficiency in NRM, and self-reliance to the extent possible , in harmony
    with nature and the environment.
  3. Dinesh, S., Faudzi, M.M., Rafidah, M., Shakhira, B.N.I., Robiah, A.S., Shalini, S.S., et al.
    ASM Science Journal, 2014;8(1):11-20.
    MyJurnal
    In this study, Global Positioning System (GPS) simulation was employed to study the effect of radio frequency interference (RFI) on two hand-held GPS receivers; Garmin GPSmap 60CSx (evaluated GPS receiver) and Garmin GPSmap 60CS (reference GPS receiver). Both GPS receivers employed the GPS L1 coarse acquisition (C/A) signal. It was observed that the interference signal power levels required to affect the location fixes of the GPS receivers were significantly high compared to the corresponding GPS signal power levels. The noiselike C/A code structure, which modulated the L1 signal over a 2 MHz bandwidth, allowed for the signal to be received at low levels of interferences. The evaluated GPS receiver had better RFI operability as compared to the reference GPS receiver. This is because the evaluated GPS receiver had higher receiver sensitivity, allowing it to have increased carrier-to-noise density (C/N0) levels for GPS satellites tracked by the receiver. The absence of other error parameters, including ionospheric and tropospheric delays, satellite clock, ephemeris and multipath errors, and unintentional signal interferences and obstructions, resulted in the required minimum jamming power levels in this study to be significantly higher as compared to field evaluations. These minimum jamming power levels vary with location and time. This was due to the GPS satellite constellation being dynamic, causing varying GPS satellite geometry over location and time, resulting in the minimum required GPS jamming power levels being location / time dependent. In general, the lowest minimum jamming power levels were observed for readings with the highest position dilution of precision (PDOP) values, and vice versa.
  4. Dinesh, S.
    ASM Science Journal, 2010;4(1):62-73.
    MyJurnal
    Studies conducted on the various geometric properties of skeletons of water bodies have shown highly promising results. However, these studies were made under the assumption that water bodies were static objects and that they remained constant over time. Water bodies are actually dynamic objects; they go through significant spatio-temporal changes due to drought and flood. In this study, the characterization of skeletons of simulated drought and flood of water bodies was performed. It was observed that as the drought level increased from 1 to 9, the average length of the skeletons decreased due to reduction in the size of the water bodies and increase in the number of water bodies. As the drought level increased from 9 to 15, the average length of the skeletons increased further due to vanishing of small water bodies. Flood caused an increase in the average length of the skeletons due to merging of adjacent water bodies. Power law relationships were observed between the average length of the skeletons of the simulated drought/flood and the level of drought/flood. The scaling exponent of these power laws which was named as a fractal dimension, indicated the rate of change of the average length of the skeletons of simulated drought/flood of water bodies over varying levels of drought/flood. However, errors observed in the goodness of fit of the plots indicated that monofractals were not sufficient to characterise the skeletons of simulated drought and flood of water bodies. Multifractals and lacunarity analysis were required for more accurate characterisation.
  5. Djauhari, M.A.
    ASM Science Journal, 2016;9(2):1-8.
    MyJurnal
    The paradigm that mathematics is a subject to be taught and learned is not correct. Mathematics is to be
    produced. However, without hermeneutics, it would be difficult to do so. Unfortunately, hermeneutics was
    all that have been neglected in mathematics education. Meanwhile, only with hermeneutics, teaching
    and learning mathematics and also research in mathematics could flourish and be fruitful. Without it,
    it would be extremely hard for students to come up with a new creation in mathematics. This paper
    aims to shift the paradigm of mathematics education from learning (only) of mathematics into producing
    mathematics. Some examples are presented to illustrate the power of hermeneutics in developing
    mathematical imagination, ideas, and creativity towards mathematical discovery or invention.
  6. Djauhari, M.A.
    ASM Science Journal, 2011;5(1):53-63.
    MyJurnal
    Industrial statistics is an important part of the management system in any industry that strives to continuously improve quality and increase productivity and efficiency. That system covers supply chain management, production design and prototyping, production process and marketing. Industrial statisticians, industrial engineers and industrial leaders should work together hand in hand, in the same language, to ensure that the process and products are as expected. The system itself is never complete. Thus, the usefulness, manageability and reliability of all statistical models used in the system are to be considered as first priority, but those skills are not sufficient. Industrial statisticians should also, of course, be able to come and go between the two poles: statistics and industry. This requirement needs a good understanding about the culture of these poles and how to conduct a mutual symbiosis. One of the principal bridges between these cultures is statistical process control (SPC). This paper is to show that modern industry cannot escape from SPC, especially in a multivariate setting. This setting, which characterizes modern industry, consists of two philosophical problems: how to order data and how to measure process variability. Our recent research results sponsored by the Government of Malaysia will be presented to illustrate the challenging statistical problems in modern industry.
  7. Djauhari, M.A., Gan, S.L.
    ASM Science Journal, 2014;8(2):150-158.
    MyJurnal
    We had reviewed the current practice in stocks market analysis where stock is represented by its closing price, and then found that this approach may be misleading. In actuality, in the daily activity of stocks market, stock is represented by four prices, namely opening, highest, lowest, and closing prices. Thus, stock is a multivariate time series of those four prices and not a univariate time series of closing price only. In this paper all four prices will be considered. Then, the notion of multivariate time series similarity among stocks will be developed as a generalisation of univariate time series similarity. The results are used to construct stocks network in multivariate setting. To filter the economic information contained in that network, the standard tools in econophysics is used. Furthermore, the topological properties of stocks are analysed by using the most common centrality measures. As an example, Bursa Malaysia data are investigated and we show that the proposed approach can better figure out the real situation compared to the current one.
  8. Djauhari, M.A.
    ASM Science Journal, 2011;5(2):123-137.
    MyJurnal
    Almost a half century after it was introduced, Wilks’ statistic has come into application in industrial manufacturing process variability monitoring. This is an important breakthrough in the way experts monitor the variability of manufacturing processes which is vital in modern industry. It leaves behind the traditional practice characterized by the use of sample size n which equals 1, if the process variability monitoring is based on individual observations and is greater than the number of variables p if one works with subgroup observations. The use of Wilks’ statistic allows us to work with n < p. This paper contains a review on process variability monitoring based on individual observations. First, some historical backgrounds of process variability monitoring in the general scheme was reviewed before it was revealed where the philosophy of Wilks’ statistic could be further interpreted. Subsequently it was indicated that the way to monitor the process variability depended on how the variability itself was measured. Finally, a new statistic for detecting the shift in variability based on individual observations was introduced and then a new control chart was proposed. The performance of the proposed chart as compared with Wilks chart, was quite promising. Therefore, some recommendations were given to better understand the history of manufacturing process variability.
  9. Durairaj, R., Leong, K.C., Chia Wea, L., Wong, M.C.
    ASM Science Journal, 2011;5(2):109-114.
    MyJurnal
    Lead-free solder paste printing processes account for the majority of assembly defects in the electronic manufacturing industry. In the stencil printing process, the solder paste must be able to withstand low and high shear rates which result in continuous structural breakdown and build-up. This study investigated the effect of the addition of nickel and platinum powders to the thixotropic behaviour of lead-free Sn/Ag/Cu solder pastes using the structural kinetic model. A hysteresis loop test and constant shear test were utilized to investigate the thixotropic behaviour of the pastes using parallel plate rheometry at 25ºC. In this study, the shear rates were increased from 0.01 s–1 to 10 s–1 and the second curve was a result of decreasing the shear rate from 10 s–1 to 0.01 s–1. For the constant shear test, the samples were subjected to five different shear rates of 0.01s–1, 0.1s–1, 1s–1, 10s–1 and 100s–1. The constant shear rate test was designed to study the structural breakdown and build-up of the paste materials. From this investigation, the hysteresis loop test was shown to be an effective test method to differentiate the extent of structural recovery in the solder pastes. All the pastes showed a high degree of shear thinning behaviour with time. This might be due to the agglomeration of particles in the flux that prohibited paste flow under low shear rate. The action of high shear rate would break the agglomerates into smaller pieces which facilitated the flow of pastes, thus viscosity was reduced at high shear rate.
  10. Engku Ali, E.A.G., Matori, K.A., Saion, E., Aziz, S.H.A., Zaid, M.H.M., Alibe, I.M.
    ASM Science Journal, 2018;11(101):75-85.
    MyJurnal
    In this study, Zn2SiO4 composite-based ceramic was synthesised using amorphous SiO2
    nanoparticles as a silicon source. Different ratios of Zn:Si were prepared by mixing amorphous
    SiO2 nanoparticles with aqueous zinc nitrate. Amorphous SiO2 nanoparticles were
    encapsulated by the zinc source in aqueous solution, dried, and subjected to heat treatment.
    The heat treatment underwent by the amorphous SiO2 nanoparticles, with zinc source mixture,
    showed the changing of phases, morphology, and size with increased temperature. ZnO
    phase appeared at the beginning of heat treatment and Zn2SiO4 phase started to emerge at
    800◦C onwards, as shown by XRD patterns. The average crystallite size increases from 37
    nm at 600 ◦C to 68 nm at 1000 ◦C. The spherical morphology was observed at 600 and 700
    ◦C, but at temperatures higher than 800 ◦C, the dumbbell or necking-like structures formed.
    Optical band gap analysis of Zn2SiO4 composite was determined to be within the range of
    3.12 ± 0.04 to 3.17 ± 0.04 eV. The photoluminescence of treated samples showed emission
    peaks at 411 and 455 nm wavelengths from ZnOs blue band and at 528 nm wavelength from
    Zn2SiO4
    0
    s green band. The diffusion of zinc ions into Zn2SiO4 composite with high surface
    area will favour the diffusion at a much lower temperature compared to a conventional solid
    state method.
  11. F. Nurhaziqah K., Sheng, C.K., Amin, K.A.M., Isa, M.I.N., Hassan, M.F., Ali, E.A.G.E., et al.
    ASM Science Journal, 2018;11(101):68-74.
    MyJurnal
    The new microelectronic products require the silicon (Si) wafer to be thinned to less than
    150 µm in thickness. Residual defect on the wafer surface that leads to wafer breakage with
    a rough surface still be produced by mechanical grinding. Thus, chemical etching method is
    essentially applied to produce a reliable thin wafer with smooth surface of desired thickness.
    In this work, we studied the wet chemical etching effect of different HNO3 concentrations on
    total thickness and weight loss, etch rate, morphological and structural properties of Si wafer
    in the mixtures of HNO3 and HF. The results showed that the total thickness and weight
    loss increases with the increasing of HNO3 concentration and etching time. Higher HNO3
    concentration causes higher etch rate, and the etch rate decreases at prolonged etching time.
    A smoother and clearer homogeneous Si surface image was observed by optical microscope as
    the etching time and HNO3 concentration increase. XRD analysis shows that the intensity
    of etched Si wafer is higher than the pure one, which might indicate the smoother surface
    formation after etching. The findings of present study can be valuably referred to produce
    a reliable and desired Si thin wafer which is crucial in integrated circuit fabrication.
  12. Fauzi, R., Salazar, D.M., Kadzim, R.M., Hussin, A., Burbano, L.
    ASM Science Journal, 2009;3(2):161-167.
    MyJurnal
    In this project, a Geographic Information System (GIS) was used to collect and compile various field data in the Pedro Vicente Maldonado Ecuadorian Scientific Station Antarctica Base area. The main source of data was obtained from a global positioning system (GPS) survey using kinematic GPS (GPS-RTK) which allowed continuous point mapping in the terrain. GPS units were utilized in the collection of spatial data for all field work. The co-ordinates obtained were used to produce a point map which was then exported into GIS software where the proximity of cartographic phenomena and boundaries were mapped. All the collected data were subsequently gathered to develop the GIS database which was then used to generate and compile different maps to test for spatial and temporal relationships. The output of the project comprises a GIS database, spatial maps and 3D terrain model of the area. The developed GIS database can be used with other ecological datasets to provide biogeographical information, potential range distribution and sampling adequacy. The database is also applicable to geographical management and multi-disciplinary research projects.
  13. Fazliah, S.N., Jaafar, S., Shamsuddin, S., Zainudin, Z., Hilmi, A.B., Razila, A.R., et al.
    ASM Science Journal, 2010;4(1):1-14.
    MyJurnal
    Stem cells from human extracted deciduous teeth (SHED) have the ability to multiply much faster and double their population in culture at a greater rate, indicating that it may be in a more immature state than other type of adult stem cells. Mesenchymal stem cells (MSC) from human primary molars were isolated and cultured in media supplemented with 20% fetal bovine serum. The MSCs were confirmed using CD 105 and CD 166 and the identification of the osteoblast cells were done using reverse transcriptase polymerase chain reaction (RT-PCR) analysis. Differentiated osteoblast cells (DOC) were characterized by alkaline phosphotase and von Kossa staining followed by immunocytochemistry staining using osteocalcin and osteonectin antibodies. Further validation of SHED was done by RT-PCR to detect the presence of insulin-like growth factor 2 (IGF-2) and discoidin domain tyrosine kinase-2 (DDTK-2) transcripts, while the presence of Runx-2 mRNA was used to characterize DOC. The results showed that SHED was found positive for CD 105 and CD 166 and could differentiate into osteoblast, bone forming cells. The findings revealed the presence of distinct MSC population which had the capability to generate living human cells that could be a possible source for tissue engineering in the future.
  14. Ghazally Ismail
    ASM Science Journal, 2011;5(1):73-74.
    MyJurnal
    Human activity has ‘very likely’ been the primary cause of global warming since the start of the Industrial Revolution (18th–19th century). As a new player in industrial transformation, Malaysia can choose to ignore the warnings of global warming. blame. This may not augur well. Release of greenhouse gases have been categorically linked to climate change and global warming. In her march towards industrialization, Malaysia too has contributed to the release of greenhouse gases. Apart from those arising from natural sources, the industrial sector in Malaysia also releases other types of gases such as the fluorocarbons. This is evident from the worsening air quality in some of our cities. (Copied from article).
  15. Goh, P.S., Ismail, A.F., Ng, B.C., Sumner, T.
    ASM Science Journal, 2014;8(2):125-133.
    MyJurnal
    This study was conducted to prepare a mixed matrix membrane (MMM) and to test the performance of the prepared MMM for CO2 and CH4 gas separation. MMM containing polyethersulfone (PES) and multi-walled carbon nanotubes (MWCNTs) was prepared by a dry-wet phase inversion technique using a pneumatically-controlled membrane casting machine. The surface modification was performed on MWCNTs in order to enhance the selectivity of CO2/CH4. The surface modification of MWCNTs using chemical and physical approaches has been adopted. Mixed acid (HNO3/H2SO4) and β-CD were used for chemical and physical approaches, respectively. Effects of surface modification on MWCNTs/PES MMM were investigated. MWCNTs/PES MMMs were characterised using scanning electron microscopy (SEM), the Fourier Transform Infrared (FT-IR) spectroscopy and pure gas permeation test. The permeability and selectivity, which are the parameters describing membrane performance were calculated via the data obtained from pure gas permeation test with the feed pressure difference from 3 to 7 bars. In this study, surface modified MWCNTs/PES MMM using mixed acid and β-CD has successfully enhanced the CO2/CH4 selectivity by 40.6% compared to that of neat PES.
  16. Hamzah, I.H., Sidek, O., Abd Manaf, A.
    ASM Science Journal, 2010;4(2):142-148.
    MyJurnal
    A preliminary study was carried out to fabricate a three electrode system based on electrochemical sensoring. The cyclic voltammetry (CV) technique was chosen to select the type of metal suitable for evaporation and to compare the results produced from the fabricated gold electrode with the conventional macro-electrode system. The methodology and apparatus used involved low cost apparatus and methodology such as soft lithography, wet-etching, thermal evaporation, direct current sputtering, polymethylmethacrylate moulding and polydimethylsiloxane coating. The experiment was conducted at a fixed scan rate of 100 mV/s by using 0.01 M K3Fe(CN)6 in 0.1M KCl and well known method using Randles-Sevcik equation, peak current ratio and voltage separation was used to analyze the characterization on the fabricated sensors. Electrodes of 6.5 mm2 and 0.26 mm2 were fabricated to prove the adsorption effect of the reactant and the influence of the electrode area on the value of the peak current. CV analysis proved that the fabricated sensor was reliable for a range of 24 h at 25ºC room temperature.
  17. Harun, S.W., Sulaiman, A.H., Ahmad, H.
    ASM Science Journal, 2009;3(1):27-30.
    MyJurnal
    We demonstrate a multi-wavelength light source using a semiconductor optical amplifier (SOA) in conjunction with an array waveguide grating (AWG). The experimental results showed more than 20 channels with a wavelength separation of 0.8 nm and an optical signal-to-noise ratio of more than 10 dB under room temperature. The channels operated at the wavelength region from 1530.4 nm to 1548.6 nm, which corresponded to AWG filtering wavelengths with SOA drive current of 350 mA. The proposed light source had the advantages of a simple and compact structure, multi-wavelength operation and the system could be upgraded to generate more wavelengths.
  18. 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.
  19. Harun, S.W., Hofmann, P., Schulzgen, A., Li, L., Peyghambarian, N., Ahmad, H.
    ASM Science Journal, 2008;2(2):149-152.
    MyJurnal
    A distributed feedback fibre laser made of highly Er-Yb co-doped phosphate glass fibre was demonstrated experimentally. The 45 mm long fibre laser device operated at 1540 nm with more than 50 dB side mode suppression ratio. However, the output power was still relatively lower due to un-optimized grating structure and thermal management.
  20. Hashida, N.H., Abdullah, R.B.
    ASM Science Journal, 2008;2(1):65-73.
    MyJurnal
    This study was carried out to compare the ultrastructure of fresh, capacitated and acrosome-reacted sperm. The sperm was treated with heparin for capacitation and calcium ionophore for acrosome reaction induction. Sperm samples were then prepared for ultrastructural studies and examined by transmission electron microscopy (TEM). Ultrastructural changes in plasma and acrosomal membranes, shape of the mitochondria and outer dense fibres, in capacitated and acrosome-reacted sperm were evident. The plasma membrane of fresh sperm was loosely fitted around the sperm head and the acrosomal membrane was closely opposed to the nucleus. The plasma and acrosomal membranes of the capacitated sperm were expanded, but disintegrated in the acrosome-reacted sperm. Mitochondria of fresh sperm appeared to be rounded in shape with plasma membrane closely opposed to it and the nine outer dense fibres were almost regular rounded in shape. However, in both capacitated and acrosome-reacted sperm, the mitochondria were almost regular and elongated in shape whilst the outer dense fibres were irregular in shape in the capacitated and acrosome-reacted sperm. There were no noticeable morphological changes found in the axonemal complexes in fresh, capacitated and acrosome-reacted sperm. Ultrastructural studies are able to provide detailed information on sequential events involving numerous physiological changes during fertilization.
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