Browse publications by year: 2014

  1. Faridah Yunos, Kamel Ariffin Mohd Atan, Muhammad Rezal Kamel Ariffin, Mohamad Rushdan Md Said
    MyJurnal
    Elliptic curve cryptosystems (ECC) provides better security for each bit key utilized compared to the RSA cryptosystem. For this reason, it is projected to have more practical usage than the RSA. In ECC, scalar multiplication (or point multiplication) is the dominant operation, namely, computing nP from a point P on an elliptic curve, where n is an integer defined as the point resulting from adding P + P + ... + P, n times. However, for practical uses, it is very important to improve the efficiency of the scalar multiplication. Solinas (1997) proposes that the τ-adic Non-Adjacent Form (τ-NAF) is one of the most efficient algorithms used to compute scalar multiplications on Anomalous Binary curves. In this paper, we give a new property (i.e., Theorem 1.2) of τ-NAF(n) representation for every length, l. This is useful for evaluating the maximum and minimum norms occurring among all length-l elements of Z(τ). We also propose a new cryptographic method by using randomization of a multiplier n to nr an element of Z(τ). It is based on τ-NAF. We focused on estimating the length of RTNAF(nr) expansion by using a new method.
    MeSH terms: Algorithms; Computers; Paper; Random Allocation
  2. Siti Khuzaimah AS, Aini A, Surindar Kaur SS, Hayati Adilin MAM, Padma AR
    MyJurnal
    Self-care behaviour involves all activities type 2 diabetes patients engage in to care for their disease. In our local population, however, most patients do not manage their disease appropriately. This study aimed to determine the level of self-care behaviour and to examine the differences in self-care behaviour according to type 2 diabetes patients’ demographic data and health condition at University Malaya Medical Centre. Sample of this study comprised 388 patients (respondents) and data were collected from December 2010 to February 2011 using self-administered questionnaires. Results showed that the level of self-care behaviour was moderately high (mean = 38.94, SD=11.93). There were significant differences between self-care behaviour and ethnicity [Wilk’s Lambda = 0.92, F(12, 1008) = 2.70, p < 0.05], age group [Wilk’s Lambda = 0.96, F(4, 383) = 4.39, p < 0.05], education level [Wilk’s Lambda = 0.94, F(12, 1008) = 1.85, p < 0.05], type of treatment [Wilk’s Lambda = 0.92, F(12, 1008) = 2.84, p < 0.05], health education [Wilk’s Lambda = 0.97, F(4, 383) = 3.33, p< 0.05]. Respondents who are Indian, elderly, had lower level of education, on insulin treatment, had received health education on diabetes and not smoking had better self-care behaviour scores. It can be concluded that high risk type 2 diabetes patients should be taught individually so as to help them improve physical and psychological outcome.
    Study site: diabetic clinic; medical, nephrology, orthopedic, and surgery wards, University Malaya Medical Centre (UMMC)
    MeSH terms: Aged; Demography; Diabetes Mellitus, Type 2; Ethnic Groups; Health Education; Hospitals, University; Humans; Malaysia; Outpatient Clinics, Hospital; Surveys and Questionnaires; Self Care; Smoking; Disease Management; Insulins
  3. Nadiya T. Al-alusi, Mahmood A. Abdullah
    MyJurnal
    During recent years, extensive development has been made to improving vaccines for tuberculosis. This is due to the presence of genome sequences of diverse mycobacterial species and Mycobacteroum tuberculosis (M. tuberculosis) isolates which has led to advances in the characterization of genes and antigens of M. tb and better realization of protective immune responses to the disease in both animals and humans. This review summarizes vaccine types, reasons for variable efficacy of BCG, latest advances in tuberculosis vaccine development and major vaccine design strategies.
    MeSH terms: Animals; Humans; Mycobacterium bovis; Mycobacterium tuberculosis; Tuberculosis; Tuberculosis Vaccines
  4. Shodiya, S., Azhar, A. A., Darus, A. N.
    MyJurnal
    HCFCs, in addition to destroying the ozone layer, have been recognized as a contributing factor that increases global warming. It is widely used as working fluid in window air-conditioning system, where capillary tube serves as an expansion device. Literature reports have shown that no single refrigerant can solve the problem of ozone layer depletion and global warming. Refrigerant HC290/HC600a/HFC407C mixture, an eco-friendly refrigerant, has been recognized as an alternative to HCFC22. The objective of this study is to, for cost effectiveness, develop an empirical correlation to predict the refrigerant HC290/ HC600a/HFC407C mixture mass flow rate using statistical experimental design approach. A review of relevant literature shows that refrigerant’s mass flow rate depends on condensing temperature, degree of subcooling, inner diameter and length of capillary tube. The relationship between the mass flow rate and the four independent variables was established as an empirical mathematical correlation using central composite design (CCD), a response surface methodology (RSM). This empirical correlation was examined using analysis of variance (ANOVA) of 5% level of significance. The results of these analysis showed that the correlation fitted well with the experimental data yielding an average and standard deviation of 1.05% and 2.62%, respectively. The validity of the present correlation was further assessed by comparing it with published empirical correlation in literature and the result showed that the present correlation is consistent.
    MeSH terms: Air Conditioning; Analysis of Variance; Cost-Benefit Analysis; Molecular Weight; Research Design; Temperature; Pharmaceutical Solutions; Global Warming; Stratospheric Ozone; Ozone Depletion
  5. Ramlan, O., Noraswana, N. F.
    MyJurnal
    A study on the distribution of Recent Ostracoda in offshore sediment was carried out around the South China Sea. A total of 30 sediment samples were taken from the sampling stations between latitude 1°48’ and 7°25’N and longitude 102°09’ and 105°16’E. From this study, 79 species of ostracods belonging to 16 families and 44 genera were identified. The dominant species was Foveoleberis cypraeoides with 937 individuals obtained. There were 13 to 43 species in total. Diversity Index, H(s), was in the range of 2.1 to 3.3, whereas the dominance values were between 4.4 and 14.7%. Several environmental parameters were measured including depth, temperature and salinity. The range values for each of these parameters are 13-72 m, 25.24-30.06o C and 27.74-34.91 ppt, respectively. The sediment texture in this study area can be categorized as sand, sandy mud, clayey mud, silty mud, silty clay, clayey sand, clayey silt and silty sand. The observations revealed that abundance and diversity of ostracod appeared to be principally controlled by depth. Two faunal assemblages were identified in terms of faunal composition, namely, shallow water (Hemikrithe orientalis, Neomonoceratina iniqua, Stigmatocythere indica, Cytherelloidea leroyi and Neocytheretta snellii) and deep water (Paracypris sp., Alataconcha pterogona, Bythocytheropteron alatum, Keijella paucipunctata and Actinocythereis scutigera). A comparative analysis showed a high degree resemblance between the study area and south-eastern Malay Peninsula (the South China Sea).
    MeSH terms: Aluminum Silicates; Animals; Arthropods; China; Crustacea; Environment; Malaysia; Temperature; Water; Salinity
  6. Abidin, N. Z., Adam, M. B., Midi, H.
    MyJurnal
    Extreme Value Theory (EVT) is a statistical field whose main focus is to investigate extreme phenomena. In EVT, Fréchet distribution is one of the extreme value distributions and it is used to model extreme events. The degree of fit between the model and the observed values was measured by Goodness-of-fit (GOF) test. Several types of GOF tests were also compared. The tests involved were Anderson-Darling (AD), Cramer-von Mises (CVM), Zhang Anderson Darling (ZAD), Zhang Cramer von-Mises (ZCVM) and Ln. The values of parameters μ, σ and ξ were estimated by Maximum Likelihood. The critical values were developed by Monte-Carlo simulation. In power study, the reliability of critical values was determined. Besides, it is of interest to identify which GOF test is superior to the other tests for Fréchet distribution. Thus, the comparisons of rejection rates were observed at different significance levels, as well as different sample sizes, based on several alternative distributions. Overall, given by Maximum Likelihood Estimation of Fréchet distribution, the ZAD and ZCVM tests are the most powerful tests for smaller sample size (ZAD for significance levels 0.05 and 0.1, ZCVM for significance level 0.01) as compared to AD, which is more powerful for larger sample size.
    MeSH terms: Biometry; Models, Theoretical; Monte Carlo Method; Reproducibility of Results; Likelihood Functions; Sample Size
  7. Hazizi, A. S., Zahratul Nur, K., Mohd Nasir, M. T., Zaitun, Y., Tabata, I.
    MyJurnal
    The aim of this study was to compare physical activity prevalence estimates among the International Physical Activity Questionnaire (IPAQ), steps/day, and accelerometer in a sample of government employees in Kangar, Perlis, Malaysia. Ten government agencies in Kangar were randomly chosen, and all employees were invited to participate. A self-administered questionnaire was employed to obtain information on socio-demographic characteristics and a physical activity assessment using the IPAQ. Anthropometric measurements, which include measurements of weight, height, body mass index, percent body fat, waist and hip circumference, were carried out. An accelerometer was used to assess total daily energy expenditure and the number of steps/day. A total of 272 respondents were involved in this study with a response rate of 83.2%. According to IPAQ, accelerometer and steps/day, the majority of the respondents (22.0%, 55.1%, and 77.6%, respectively) were classified as sedentary. The agreement between physical activity level as determined by the accelerometer vs. the IPAQ (Kappa=-0.46 {95% CI -0.384,-0.536}, p=0.238) and the IPAQ vs. steps/day (Kappa =0.037 {95% CI 0.090,-0.016}, p=0.175) was not significant, but the agreement between physical activity level as determined by the accelerometer vs. steps/day was classified as fair (Kappa=0.296 (95% CI 0.392, 0.200}, p
    MeSH terms: Adipose Tissue; Body Weight; Cross-Sectional Studies; Energy Metabolism; Government Agencies; Humans; Malaysia; Motor Activity; Surveys and Questionnaires; Exercise; Body Mass Index; Prevalence
  8. Bande, Y. M., Mariah, N. A.
    MyJurnal
    In this study, various methods and applications of flat plate solar collectors are discussed and pictorial representations are presented. Low temperature applications of flat plate collectors are identified in solar cooking, solar water heating, space and air heating, industrial heating plants and in agricultural produce drying processes. Basic equations, as presented by many researchers in the performances of flat plate collectors, are also presented. The review discusses the analysis of losses from flat plate collectors towards obtaining the overall heat loss coefficient which indicate the performance of flat plate collectors.
    MeSH terms: Body Temperature Regulation; Cold Temperature; Cooking; Desiccation; Heating; Research Personnel; Sunlight; Temperature; Water
  9. Said S. E. H. Elnashaie
    MyJurnal
    Bifurcation and chaos are important phenomena affecting many physical and chemical systems. They are also related to the stability/instability and multiplicity phenomena associated with these systems. The phenomena are not only of theoretical/mathematical interest but are also important for laboratory, pilot plant and commercial units. This paper concentrates on 3 systems:

    1. The novel auto-thermic Circulating Fluidized Membrane Steam Reformer (CFBMSR) for the efficient production of the clean fuel hydrogen and which shows multiplicity of the steady state (static bifurcation)

    2. A novel fermentor for the efficient production of bio-ethanol that shows static/dynamic bifurcation as well as chaotic behaviour

    3. The neurocycle of the acetylcholine transmitter in the brain using diffusion-reaction models in order to gain insight into their possible connection to Alzheimer and Parkinson Diseases (AD/PD); these are preliminary efforts to investigate the bifurcation and chaotic behaviour of this neurocycle.
    MeSH terms: Acetylcholine; Ethanol; Brain; Diffusion; Hydrogen; Membranes; Parkinson Disease; Steam; Bioreactors
  10. M. V. Prasanna, R. Nagarajan, A. Elayaraja, S. Chidambaram
    MyJurnal
    Surface water samples were collected from 16 Lakes in and around Miri City to assess the electrochemical parameters includes pH, Electrical conductivity (EC), Total dissolved solid (TDS), redox potential (Eh), resistivity and salinity. Sampling locations for monitoring were selected in the vicinity of major roads, industries, settlements and agricultural region. Interpretation of data shows that the surface water in the central region of the study area is polluted by various anthropogenic activities, while in the southern part is within the limits of guideline values. This kind of investigation is essential in the study area to save the resources for future perspective. Further detailed studies are also needed to get a clear picture of the surface water quality in Miri city and for future sustainable management of this resource.
    MeSH terms: Agriculture; Cities; Electric Conductivity; Industry; Oxidation-Reduction; Water; Salinity; Lakes; Water Quality
  11. M. Jayaprakash, R. Nagarajan, P. M. Velmurugan, L. Giridharan, [email protected], B. Urban
    MyJurnal
    The composite nature of Ennore Creek, receiving polluted waters from Buckingham canal, River Kortalaiyar, and the presence of numerous industries rapidly degrade the coastal environment. In this study, multivariate statistical technique was used to assess the nature of pollution and to identify the factors responsible for the enrichment of trace metals in the creek sediments. Forty samples were collected during pre- and post-monsoon periods to evaluate the seasonal variations on the concentration of trace metals in the sediments. The results indicate that not much seasonal variation exists in the concentration of trace metals in the sediments of Ennore creek. Results of the cluster analysis illustrate that the enrichment of trace metals was mainly from anthropogenic sources. Meanwhile, correlation coefficient among the metals reveals that some of the metals (Fe and Al) derived were of natural origin. The complex data matrix of the sediment were interpreted after reduction to three factors and the results illustrate the extent of the influence of anthropogenic activities. The spatial distribution diagrams demonstrate and demarcate the region of enrichment of metals in the sediments of Ennore creek.
    MeSH terms: Metals; Seasons; Trace Elements; Water Pollution; Rivers
  12. S. Bhatia, K. T. Lee, A. R. Mohamed, Sumathi, S.
    MyJurnal
    Simultaneous removal of SO2 and NO from simulated flue gas by cerium oxide supported over palm shell activated carbon (Ce/PSAC) was studied in a fixed bed adsorber. In this study, the adsorption breakthrough of SO2 and NO on Ce/PSAC at different reaction temperatures was manipulated to test their applicability to a model developed by Yoon and Nelson (1984) for breakthrough curves. Yoon and Nelson (1984) developed a relatively simple model addressing the adsorption and breakthrough of adsorbate vapour with respect to activated charcoal. This model was based on the assumption that the rate of decrease in the probability of adsorption for each adsorbate molecule is proportional to the probability of adsorbate adsorption and the probability of adsorbate breakthrough on the adsorbent. A regression analysis (least square method) has been used to give the model parameters of k and t1/2. The results showed that the agreement between the model and the experimental results is satisfactory. From the observation, it is concluded that the simple two-parameter model of Yoon and Nelson’s model can be applied for modelling the breakthrough curves of SO2 and NO gas adsorption over Ce/PSAC.
    MeSH terms: Adsorption; Cerium; Charcoal; Models, Theoretical; Probability; Temperature; Models, Statistical; Least-Squares Analysis
  13. 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.
    MeSH terms: Electricity; Paper; Radiation, Nonionizing; Water
  14. Yusoff, W. F. M., Sapian, A. R., Salleh, E., Adam, N. M., Hamzah, Z., Mamat, M. H. H.
    MyJurnal
    Stack ventilation in the hot and humid climate is inherently inefficient due to minimal air temperature differences between indoor and outdoor environment of a naturally ventilated building. Solar induced ventilation is a viable alternative in enhancing this stack ventilation. This paper aims to demonstrate investigations on the effective solar collector orientation and stack height for a solar induced ventilation prototype that utilizes roof solar collector and vertical stack. The orientation of the solar collector is significant as it determines the amount of solar radiation absorbed by the solar collector. Meanwhile, the height of the vertical stack influences the creation of the stack pressure in inducing air movement. Investigations were executed using a simulation modelling software called FloVENT. The validation of the simulation modelling against physical experiment indicated a good agreement between these two results. Analyses were executed on the air temperature increments inside the solar collector. A high increment of the air temperature resulted in the effective orientation. Meanwhile, the air temperature and mass flow rate of the various heights of the vertical stack were also analyzed. The findings concluded that the recommended orientation for the prototype’s solar collector is the west-facing orientation. It was also found that the higher the vertical stack, the lower the air temperature inside the stack would be, but with greater induced mass flow rate.
    MeSH terms: Fluticasone; Air Movements; Climate; Environment; Software; Solar Energy; Temperature; Ventilation
  15. Diyana Jamaludin, Desa Ahmad, Rezuwan Kamaruddin, Hawa Z. E. Jaafar
    MyJurnal
    Tropical greenhouses require active evaporative cooling system such as pad-and-fan to ensure a suitable microclimate for crop production. Excess heat causes indoor temperature to become hotter than desired resulting in detrimental effects to crop growth and production. Solar radiation intensity and outside temperature affect temperature and relative humidity level inside a greenhouse, while wide gradients in temperature and relative humidity can cause problems related to crop growth and production uniformity. A 300 m2 greenhouse, equipped with evaporative pad and four exhaust fans at each end walls, was used in the study. Horizontal and vertical profiles of the temperature and relative humidity inside the greenhouse were investigated. Results showed that temperature increased from evaporative pad area to exhaust fans area in a horizontal plane, while relative humidity showed an inverse pattern from temperature. In the vertical plane, temperature increased, while relative humidity decreased from lower level to the upper level. ANOVA results showed that in overall, temperature and relative humidity inside the greenhouse were uniform as there was no significant difference at 95% confidence interval. Thus, it was concluded that greenhouse cooling system by evaporative pad and exhaust fans are suitable for application in a tropical country such as Malaysia.
    MeSH terms: Crop Production; Analysis of Variance; Clothing; Hot Temperature; Humidity; Malaysia; Microclimate; Solar Energy; Temperature; Confidence Intervals; Biological Processes; Physiological Processes
  16. Augustine Chioma Affam, Malay Chaudhuri, Shamsul Rahman Mohammed Kutty
    MyJurnal
    The study examined modified Fenton (FeGAC/H2O2) pretreatment of the antibiotics amoxicillin and cloxacillin in aqueous solution for biological treatment. The treatment was optimized by the response surface methodology (RSM). The optimum operating conditions at pH3 were H2O2/COD molar ratio 2.0, FeGAC dose 3.5 g/L and reaction time 90 min for 87.53% removal of COD, 78.01% removal of TOC, and 98.24% removal of NH3-N. Biodegradability (BOD5/COD ratio) improved from zero to 0.36, indicating the effluent was amenable to biological treatment. Meanwhile, FTIR spectra indicated degradation of the antibiotics. Compared with Fenton or photo-Fenton, modified Fenton (FeGAC/H2O2) was more effective in the pre-treatment of the antibiotics amoxicillin and cloxacillin in aqueous solution for biological treatment.
    MeSH terms: Amoxicillin; Anti-Bacterial Agents; Biodegradation, Environmental; Cloxacillin; Hydrogen Peroxide; Language; Reaction Time; Spectroscopy, Fourier Transform Infrared; Water Purification
  17. Fauzie, M. J., Azwan, M. M. Z., Hasfalina, C. M., Mohammed, T. A.
    MyJurnal
    Alluvial aquifers can be found in most of the coastal areas of Peninsular Malaysia. Seven tube wells located in such aquifers in the west coast of Selangor state had their performance evaluated by carryingout step drawdown tests. The performance of these wells was evaluated in terms of aquifer loss, well loss, specific capacity and well efficiency. The aquifer loss coefficient and well loss coefficient were found to be in the range of 0.0198 hrm-2 to 0.4014 hrm-2 and from 0.0001 hr2 m-5 to 0.0410 hr2 m-5, respectively. The drawdown in tube wells TW1 and TW7 is mainly influenced by well loss component as compared to the aquifer loss component, while in tube wells TW2, TW3, TW4, and TW5, the drawdown is mainly influenced by aquifer loss component. The drawdown in tube well TW6 is influenced by aquifer loss component at a low discharge rate, but at high discharge rate, it is influenced by well loss component. The specific capacity and efficiency of the tested tube wells varied from 1.329 m2 hr-1 to 40.166 m2 hr-1, and from 11% to 96%, respectively. Tube wells TW2 and TW4 are categorized as high productive wells, while tube wells TW1, TW3, TW5 and TW7 are categorized as moderate productive wells and tube well TW6 as low productive well.
    MeSH terms: Malaysia; Groundwater; Water Wells
  18. Choong Boon Ng, Wah June Leong, Mansor Monsi
    MyJurnal
    The nonlinear conjugate gradient (CG) methods have widely been used in solving unconstrained optimization problems. They are well-suited for large-scale optimization problems due to their low memory requirements and least computational costs. In this paper, a new diagonal preconditioned conjugate gradient (PRECG) algorithm is designed, and this is motivated by the fact that a pre-conditioner can greatly enhance the performance of the CG method. Under mild conditions, it is shown that the algorithm is globally convergent for strongly convex functions. Numerical results are presented to show that the new diagonal PRECG method works better than the standard CG method.
    MeSH terms: Algorithms; Memory; Motivation; Problem Solving
  19. Billa, L., Pradhan, B., Yakuup, A.
    MyJurnal
    In this paper, optimum routing was developed based on the travel salesman method and integrated in ArcInfo GIS using linear programming. The results of the optimized travel distances and times for residential waste collection and routing to disposal site were used to calculate the number and type of required track collection, labour requirement, costing of waste collection and to determine the overall solid waste management efficiency through waste management operation research methods. The objective of the study was to optimize residential collection and hauling to disposal site through operation cost minimization for Petaling Jaya Municipality in the state of Selangor, Malaysia. The study determined that with optimized routes and recycling possibilities, the total cost of waste collections could be reduced from RM90,372 to RM20,967, with a reduction of 76.8%. It was also revealed that optimum routes might not necessarily be the shortest distance from point A to point B as travel time maybe high on short distances due to traffic congestion and the presence of many traffic lights. Techniques and methods developed using general GIS have proven effective in route optimization and allowed management of data to suit local conditions and limitations of waste management for the studied area. Thus, scenarios of travel distances, time and waste quantity value generated from the GIS enabled appropriate determination of the number of waste trucks and labour requirements for the operation and the overall calculation of costs of waste management based on the operation research methods used in the study.
    MeSH terms: Cities; Malaysia; Programming, Linear; Research; Waste Management; Motor Vehicles; Recycling; Solid Waste
  20. Hong Seng Sim, Wah June Leong, Malik Abu Hassan, Fudziah Ismail
    MyJurnal
    Subspace quasi-Newton (SQN) method has been widely used in large scale unconstrained optimization problem. Its popularity is due to the fact that the method can construct subproblems in low dimensions so that storage requirement as well as the computation cost can be minimized. However, the main drawback of the SQN method is that it can be very slow on certain types of non-linear problem such as ill-conditioned problems. Hence, we proposed a preconditioned SQN method, which is generally more effective than the SQN method. In order to achieve this, we proposed that a diagonal updating matrix that was derived based on the weak secant relation be used instead of the identity matrix to approximate the initial inverse Hessian. Our numerical results show that the proposed preconditioned SQN method performs better than the SQN method which is without preconditioning.
    MeSH terms: Algorithms; Conditioning (Psychology); Costs and Cost Analysis; Social Distance
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