Displaying publications 1 - 20 of 250 in total

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  1. A. Sahed, F. B. Ismail Alnaimi
    MyJurnal
    This paper presents the numerical modelling techniques for the simulation of the energy conversion chain from wave to electricity in an Oscillating Water Column (OWC) equipped with a full-scaled self rectifying turbine. The performance of the OWC device has been assessed for the stand-alone power system of a typical Irish climatic wave condition. The results showed that the overall performance of the complete device depends on the level of turbine damping, which in turn depends on the wave climate, especially the significant wave height. Furthermore, turbine efficiency predicted using quasi-steady showed qualitatively favourable agreement with the experimental results.
    Matched MeSH terms: Paper
  2. AHMAD SHAHIR BIN JAMALUDIN, ABDULLAH BIN YASSIN
    Sains Malaysiana, 2013;42:1727-1733.
    Invention of milling combined laser sintering system (MLSS) is able to reduce the mould manufacturing time and improve the mould accuracy. Thus, more study is needed to increase the understanding for the laser sintered material machining characteristic to gain benefit from the invention of MLSS. This paper clarified the analysis of laser sintered material machinability with the application of Finite Element Method (FEM). Mild steel AISI1055 was applied in developing the Finite Element model in this study due to its popularity in machinability test and adequate level of data availability. 2D orthogonal cutting was employed on edge design tools with updated Lagrangian coupled thermo mechanical plane strain model. Adaptive meshing, tool edge radius and various types of friction models were assigned to obtain efficient simulations and precise cutting results. Cutting force and cutting-edge temperature estimated by Finite Element Method are validated against corresponding experimental values by previous researchers. In the study, cutting force increases when radial depth increases and lowest error acquired when the shear friction factor of 0.8 was applied. Machining simulation for laser sintered materials estimated lower cutting force compared with mild steel AISI1055 due to lower Young modulus. Higher cutting temperature estimated for machining simulation laser sintered material compared with machining simulation mild steel AISI1055 due to its low thermal conductivity.
    Matched MeSH terms: Paper
  3. AUDY JR
    Med J Malaya, 1959 Sep;14:1-11.
    PMID: 13795072
    Matched MeSH terms: Paper*
  4. Abdul Ghapor Hussin, Norli Anida Abdullah, Ibrahim Mohamed
    This paper gives a comprehensive discussion on complex regression model by extending the idea of regression model to circular variables. Various aspect have been considered such as the biasness of parameters, error assumptions and model checking. The advantage of this approach is that it allows the use of usual technique available in ordinary linear regression for the regression of circular variables. The quality of the estimates and the feasibility of the approach were illustrated via simulation. The model was then applied to the wave direction data.
    Matched MeSH terms: Paper
  5. Abdul Khalil HP, Davoudpour Y, Islam MN, Mustapha A, Sudesh K, Dungani R, et al.
    Carbohydr Polym, 2014 Jan;99:649-65.
    PMID: 24274556 DOI: 10.1016/j.carbpol.2013.08.069
    Nanofibrillated cellulose from biomass has recently gained attention owing to their biodegradable nature, low density, high mechanical properties, economic value and renewability. Although they still suffer from two major drawbacks. The first challenge is the exploration of raw materials and its application in nanocomposites production. Second one is high energy consumption regarding the mechanical fibrillation. However, pretreatments before mechanical isolation can overcome this problem. Hydrophilic nature of nano-size cellulose fibers restricts good dispersion of these materials in hydrophobic polymers and therefore, leads to lower mechanical properties. Surface modification before or after mechanical defibrillation could be a solution for this problem. Additionally, drying affects the size of nanofibers and its properties which needs to study further. This review focuses on recent developments in pretreatments, nanofibrillated cellulose production and its application in nanopaper applications, coating additives, security papers, food packaging, and surface modifications and also for first time its drying.
    Matched MeSH terms: Paper*
  6. Abdul Wahab MF, Mohamad Ghani NI, Kuppuswamy R
    Forensic Sci Int, 2012 Nov 30;223(1-3):53-63.
    PMID: 22955030 DOI: 10.1016/j.forsciint.2012.07.020
    Most of the automotive companies use cast iron for their engine blocks. Restoration of obliterated number on these iron surfaces by chemical etching is known to be quite difficult. Heating of the obliterated surface using oxyacetylene flame is an alternative recovery treatment suggested in literature and used in practice. However chemical etching has been established to be the most sensitive technique for detection of metal deformation present under stamped serial numbers. Hence, the current work investigated the suitability of some common etchants on cast iron surfaces with a view to determining the most suitable one for revealing the obliterated marks. The reagents tested were mostly copper containing Fry's reagent and its modifications. Two cast iron engine blocks (3.29%C and 3.1%C) of two cars--a Proton Saga and a Toyota--were utilized for the experiments. The engine blocks were cut into several small plates and each plate was stamped with some numerical characters at 8 kN load using Instron Table Mounted Universal Testing Machine. The depth of stamping impression varied between 0.2 mm and 0.3 mm. The stamped number was completely ground off manually using a metal file. The grounded surface was then polished smooth using emery papers and etched with a few selected reagents mostly by swabbing. Experimental results showed that a modified Fry's composition consisting of 4 5g CuCl(2), 100 mL HCl, and 180 mL H(2)O restored the number with better contrast at a reasonably shorter time. The above reagent is a slightly modified form of one of the Fry's original compositions--45 g CuCl(2), 180 mL HCl, and 100 mL H(2)O. Quite importantly the proposed reagent restored the original stamped numbers of both Proton and Toyota cars and also a Mitsubishi car that had been obliterated. The most widely used Fry's composition (90 g CuCl(2), 120 mL HCl and 100 mL H(2)O), although recovered the obliterated number, did not cause the desired contrast.
    Matched MeSH terms: Paper
  7. Abdulaziz O, Hashim I, Chowdhury M, Momani S
    In this paper, systems of second-order boundary value problems (BVPs) are considered. The applicability of the homotopy-perturbation method (HPM) was extended to obtain exact solutions of the BVPs directly.
    Matched MeSH terms: Paper
  8. Abdullah R, Ishak CF, Kadir WR, Bakar RA
    Int J Environ Res Public Health, 2015 Aug;12(8):9314-29.
    PMID: 26262636 DOI: 10.3390/ijerph120809314
    The disposal of industrial paper mill sludge waste is a big issue and has a great importance all over the world. A study was conducted to determine the chemical properties of recycled paper mill sludge (RPMS) and assess its possibilities for land application. RPMS samples were collected from six different paper mills in Malaysia and analyzed for physical and chemical properties, heavy metals, polycyclic aromatic hydrocarbons, (13)C-NMR spectra and for the presence of dioxins/furans. The RPMS was dewatered, sticky with a strong odour, an average moisture of 65.08%, pH 7.09, cation exchange capacity (CEC) 14.43 cmol (+) kg(-1), N 1.45, P 0.18, K 0.12, Ca 0.82, Mg 0.73, Na 0.76 and Al, 1.38%. The polycyclic aromatic hydrocarbons (PAHs) and heavy metals levels were below the standard Class 2 limits. The dioxin and furan were in below the standard concentration of Class 1. The most prominent peak in the (13)C-NMR spectra of RPMS was centered at 31 ppm, proving the presence of methylene (-CH2) groups in long aliphatic chains, with lipids and proteins. The signal at 89 ppm and highly shielded shoulder at 83 ppm were due to presence of cellulose carbon C-4, and the peak at 63 and 65 ppm was due to the cellulose carbon spectrum. The RPMS therefore contains significant amount of nutrients with safe levels of heavy metals and PAHs for environment and can be used as a fertilizer and soil amendment for land application.
    Matched MeSH terms: Paper*
  9. Abdurashid Mamadolimov, Herman Isa, Miza Mumtaz Ahmad, Moesfa Soeheila Mohamad
    MyJurnal
    A Boolean permutation is called nonlinear if it has at least one nonlinear component function. All nonlinear Boolean permutations and their complements are called non-affine Boolean permutations. Any non-affine Boolean permutation is a potential candidate for bijective S-Box of block ciphers. In this paper, we find the number of n-variable non-affine Boolean permutations up to multiplicative n and show a simple method of construction of non-affine Boolean permutations. However, non-affinity property is not sufficient for S-Boxes. Nonlinearity is one of the basic properties of an S-Box. The nonlinearity of Boolean permutation is a distance between set of all non-constant linear combinations of component functions and set of all non-affine Boolean functions. The cryptographically strong S-Boxes have high nonlinearity. In this paper, we show a method of construction of 8-variable highly nonlinear Boolean permutations. Our construction is based on analytically design (8, 1), (8, 2), and (8, 3) highly nonlinear vectorial balanced functions and random permutation for other component functions.
    Matched MeSH terms: Paper
  10. Abu Hassan Shaari Mohd Nor, Tan YL, Fauziah Maarof
    Sains Malaysiana, 2007;36:225-232.
    The main objective of this paper is to explore the varying volatility dynamic of inflation rate in Malaysia for the period from January 1980 to December 2004. The GARCH, GARCH-Mean, EGARCH and EGARCH-Mean models are used to capture the stochastic variation and asymmetries in the economic instruments. Results show that the EGARCH model gives better estimates of sub-periods volatility. Further analysis using Granger causality test show that there is sufficient empirical evidence that higher inflation rate level will result in higher future inflation uncertainty and higher level of inflation uncertainty will lead to lower future inflation rate.
    Matched MeSH terms: Paper
  11. Abubakar AR, Haque M
    J Pharm Bioallied Sci, 2020 01 29;12(1):1-10.
    PMID: 32801594 DOI: 10.4103/jpbs.JPBS_175_19
    Preparation of medicinal plants for experimental purposes is an initial step and key in achieving quality research outcome. It involves extraction and determination of quality and quantity of bioactive constituents before proceeding with the intended biological testing. The primary objective of this study was to evaluate various methods used in the preparation and screening of medicinal plants in our daily research. Although the extracts, bioactive fractions, or compounds obtained from medicinal plants are used for different purposes, the techniques involved in producing them are generally the same irrespective of the intended biological testing. The major stages included in acquiring quality bioactive molecule are the selection of an appropriate solvent, extraction methods, phytochemical screening procedures, fractionation methods, and identification techniques. The nitty-gritty of these methods and the exact road map followed solely depends on the research design. Solvents commonly used in extraction of medicinal plants are polar solvent (e.g., water, alcohols), intermediate polar (e.g., acetone, dichloromethane), and nonpolar (e.g., n-hexane, ether, chloroform). In general, extraction procedures include maceration, digestion, decoction, infusion, percolation, Soxhlet extraction, superficial extraction, ultrasound-assisted, and microwave-assisted extractions. Fractionation and purification of phytochemical substances are achieved through application of various chromatographic techniques such as paper chromatography, thin-layer chromatography, gas chromatography, and high-performance liquid chromatography. Finally, compounds obtained are characterized using diverse identification techniques such as mass spectroscopy, infrared spectroscopy, ultraviolet spectroscopy, and nuclear magnetic resonance spectroscopy. Subsequently, different methods described above can be grouped and discussed according to the intended biological testing to guide young researchers and make them more focused.
    Matched MeSH terms: Chromatography, Paper
  12. Adam, M.B., Norazman, N., Mohamad Kasim, M.R.
    MATEMATIKA, 2018;34(1):113-123.
    MyJurnal
    Logging activity is one of the most important activities for tropical countries
    including Malaysia, as it produces quality trees for papers. One of the important tree
    species is the Acacia Mangium which it produces a soft tree for papermaking enterprises.
    The papers are exported to Europe and countries which have high demand for paper
    due to the rapid development of the printing industry. Thus we analyzed the height for
    individual trees. We investigate the maximum height of the trees from 1990 to 2006
    and we fit the data using extreme value model. Some of the data are missing and three
    imputation methods we used to solve this problem.
    Matched MeSH terms: Paper
  13. Adib Kabir Chowdhur, Veeramani, Shanmugan
    MyJurnal
    In this modern world, Information Technology gives impacts on society, countries, economy, and environment. This paper discusses the positive, negative, direct and indirect impacts of IT on environmental issues. A strategy for sustainable development in ICT and its future demand are also proposed. Apart from that, a research was also done to find a quantitative indicator to show the relationship between demand in IT industry and impacts to the environment. By using a mathematical formula, an estimation of the effect to the environment can be found. By using the indicator, it is hoped that society and the IT industry will become more aware of their action to the environment.
    Matched MeSH terms: Paper
  14. Ahmad AL, Wong SS, Teng TT, Zuhairi A
    J Hazard Mater, 2007 Jun 25;145(1-2):162-8.
    PMID: 17161910
    Coagulation-flocculation is a proven technique for the treatment of high suspended solids wastewater. In this study, the central composite face-centered design (CCFD) and response surface methodology (RSM) have been applied to optimize two most important operating variables: coagulant dosage and pH, in the coagulation-flocculation process of pulp and paper mill wastewater treatment. The treated wastewater with high total suspended solids (TSS) removal, low SVI (sludge volume index) and high water recovery are the main objectives to be achieved through the coagulation-flocculation process. The effect of interactions between coagulant dosage and pH on the TSS removal and SVI are significant, whereas there is no interaction between coagulant dosage and water recovery. Quadratic models have been developed for the response variables, i.e. TSS removal, SVI and water recovery based on the high coefficient of determination (R(2)) value of >0.99 obtained from the analysis of variances (ANOVA). The optimum conditions for coagulant dosage and pH are 1045mgL(-1) and 6.75, respectively, where 99% of TSS removal, SVI of 37mLg(-1) and 82% of water recovery can be obtained.
    Matched MeSH terms: Paper*
  15. Ahmad Fuad Ab Ghani, Mohamad Kamarul Anwar Sahar, Muhammad Ridzuan Husyairi Azmi, Nurul Izzati Medon, Muhammad Syazwan Samsuri, Muhammad Syurabil Abdani
    MyJurnal
    There are several types of grating, such as platform, bridge decks and filters. In design process, there
    are several important terms that have to be prioritised; engineering design, strength to weight ratio, cost,
    maintainability, reparability etcetera. Advanced materials, such as composite materials offer great
    strength to weight ratio and high mechanical properties for grating fabrication. Furthermore the
    reparability and maintenance problems could be solved as it is anti corrosion and the long service life
    attribute of composite makes it a great design material for replacement of conventional steel or
    aluminium. Bio composites, such as bamboo and coir fiber yield advantage in terms of less cost and
    abundance availability compared to commercial unidirectional composite materials, such as glass fiber
    reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP) which is considerably
    expensive yet possess higher mechanical properties. This papers presents a conceptual design of
    grating design utilizing bamboo composite as material. Pugh method has been chosen as design criteria
    selection matrix in finalizing the design of industrial grating for scaffolding (Pugh, 1991).
    Matched MeSH terms: Paper
  16. Ahmad* M, Alsarayreh D, Alsarayreh A, Qaralleh I
    Sains Malaysiana, 2017;46:2007-2017.
    In this paper, the differential transformation method (DTM) is employed to find the semi-analytical solutions of SIS and SI
    epidemic models for constant population. Firstly, the theoretical background of DTM is studied and followed by constructing
    the solutions of SIS and SI epidemic models. Furthermore, the convergence analysis of DTM is proven by proposing two
    theorems. Finally, numerical computations are made and compared with the exact solutions. From the numerical results,
    the solutions produced by DTM approach the exact solutions which agreed with the proposed theorems. It can be seen that
    the DTM is an alternative technique to be considered in solving many practical problems involving differential equations.
    Matched MeSH terms: Paper
  17. Ahmad, Z., Wee, L.S., Fauzi, M.A.
    ASM Science Journal, 2011;5(1):27-35.
    MyJurnal
    This paper reports the mechanical properties of cement composite boards made using wood-wool from a lesser known Malaysian timber species. A total of 108 specimens were fabricated using Portland cement (Type I) and wood-wool from Kelampayan (Neolamarckia cadamba). The cement to wood ratio of the specimens was 2 to 1 by weight. The aim of the study was to determine the density; flexural, compressive and tensile strength of wood-wool cement composite boards (WWCCB) by studying boards with wood-wool sized 1.5 mm, 2.5 mm and 3.5 mm and board thickness 25 mm, 50 mm and 75mm. The physical and mechanical properties of the boards were evaluated according to ASTM D 1037-96a (Standard testing method for evaluating properties of wood-based fibre and particle panel materials) and MS934:1986. Results showed that mechanical properties of WWCCB were greatly influenced by the density; as the density decreased, the mechanical strengths also decreased. However, the strength properties of the composite boards did not display a similar trend when subjected to different types of loading conditions. The compressive strength increased with thicker boards (50 mm and 75 mm) but the modulus of elasticity and modulus of rupture declined as the thickness of the board was increased.
    Matched MeSH terms: Paper
  18. Al-Naggar, Redhwan Ahmed, Zaleha Mohd Isa, Ramli Musa
    ASEAN Journal of Psychiatry, 2010;11(2):171-179.
    MyJurnal
    Objective: This paper aimed to determine the prevalence of sleeping pills use among university students and its associated factors in Malaysia. Methods: This cross-sectional study was conducted in January 2010 among 200 Malaysia. The survey was conducted by distributing self-administered questionnaires. The questionnaire was developed based on the literature review. The students were chosen randomly using convenience sampling.
    Results: A total of 200 university students participated in this study. The prevalence of using sleeping pills among university students is 7.5%. The majority of the participants were Malay 146 (73.0%), from urban area 169 (84.5%), from medical and health sciences background 101 (50.5%). This study showed that there is a significant relationship between using sleeping pills and depression (p= 0.03). There is also a significant relationship between
    using sleeping pills and inducing sleep by reading (p=0.04). Conclusion: The prevalence of sleeping pills usage among university students is relatively high. This study showed that there is a significant relationship between using sleeping pills and depression.
    Matched MeSH terms: Paper
  19. Alanazi A, Alkhorayef M, Alzimami K, Jurewicz I, Abuhadi N, Dalton A, et al.
    Appl Radiat Isot, 2016 Nov;117:106-110.
    PMID: 26777569 DOI: 10.1016/j.apradiso.2016.01.001
    Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In such circumstance, dosimeters with atomic number similar to human tissue are needed. Carbon nanotubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nanotubes (SWCNTs) buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2Gy. This finding suggests that carbon nanotubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance.
    Matched MeSH terms: Paper*
  20. Alomari. Nashwan K., Badronnisa Yusuf, Thamer Ahmed Mohammed Ali, Abdul Halim Ghazali
    MyJurnal
    Branching channel flow refers to any side water withdrawals from rivers or main channels.
    Branching channels have wide application in many practical projects, such as irrigation and drainage
    network systems, water and waste water treatment plants, and many water resources projects. In the
    last decades, extensive theoretical and experimental investigations of the branching open channels
    have been carried out to understand the characteristics of this branching flow, varying from case
    studies to theoretical and experimental investigations. The objectives of this paper are to review and
    summarise the relevant literatures regarding branching channel flow. These literatures were reviewed
    based on flow characteristics, physical characteristics, and modeling of the branching flow.
    Investigations of the flow into branching channel show that the branching discharge depends on many
    interlinked parameters. It increases with the decreasing of the main channel flow velocity and Froude
    number at the upstream of the branch channel junction. Also it increases with the increasing of the
    branch channel bed slope. In subcritical flow, water depth in the branch channel is always lower than
    the main channel water depth. The flow diversion to the branch channel leads to an increase of water
    depth at the downstream of the main channel. From the review, it is important to highlight that most
    of the study concentrated on flow characteristics in a right angle branch channel with a rigid boundary.
    Investigations on different branching angles with movable bed have still to be explored.
    Matched MeSH terms: Paper
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