Displaying publications 1 - 20 of 811 in total

  1. A. Sahed, F. B. Ismail Alnaimi
    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.
  2. Ab. Rahman, N.S., Abd. Majid F.A., Harisun, Y., Md. Salleh L.
    Effects of different types of solvent on the antioxidant and antibacterial activity of Quercus infectoria extract have not been well documented. Therefore, extraction process was conducted using conventional Soxhlet extraction with six different types of solvent (100% methanol, ethanol, acetone, water and 70% methanol, and ethanol). High performance liquid chromatography was implemented to identify gallic acid and tannic acid in the extracts. Water extracts contained the highest concentration of both gallic acid and tannic acid compared to other types of solvent; 51.14 mg/g sample and 1332.88 mg/g sample of gallic acid and tannic acid. Meanwhile, antioxidant and antibacterial activity were tested using DPPH free radicals scavenging and disc diffusion assay. Results demonstrated that water extracts gave the highest antioxidant activity (approximately 94.55%), while acetone extract gave the largest inhibition zone for disc diffusion assay (19.00mm respectively). The results also revealed rich sources of gallic acid and tannic acid in Q. infectoria which might provide a novel source of these natural antioxidant and antibacterial activity.
  3. Abas, M.F., Aftab, S.M.A., Rafie, A.S.M., Ahmad, K.A., Yusoff, H.
    The purpose of this research is to gain initial knowledge and to predict the sustainability of an all-weather
    Micro-Aerial-Vehicle (MAV). The observed parameters are: the maximum coefficient of lift, CL and the
    changes in CL after impact, the fluctuation of CL upon entering simulated rain environment, and length of
    stability recovery in terms of time and flapping cycle, t and t/T, at flapping frequencies of 8, 16, and 24
    Hz, at t/T = 3/8 and 7/8. At 24 Hz, the increase in peak CL value after impact of entering rain environment
    is 0.59. The average fluctuations in CL occurred when entering the rain environment are 410.263. The
    stability recovery time recorded is 0.006 seconds. Small birds (especially hummingbirds) have a very
    high flapping frequency that enables them to efficiently withstand external disturbances caused by nature
    and to instantly adapt to new environments.
  4. Abd Ghani Aizat, Paiman, Bawon, Lee, Seng Hua, Ashaari Zaidon
    In this study, the effects of addition of ammonium and aluminium-based hardeners into
    urea formaldehyde resin (UF) on the physico-mechanical properties and formaldehyde
    emission of the rubberwood particleboard were investigated. Four types of hardeners,
    namely ammonium chloride (AC), ammonium sulphate (AS), aluminium chloride (AlC)
    and aluminium sulphate (AlS), were added into UF resin. The acidity, gelation time,
    viscosity and free formaldehyde content of the UF/hardener mixtures were determined.
    Particleboard made with the UF/hardener mixtures were tested for physico-mechanical
    properties and formaldehyde emission. The pH values of the resin after addition of
    aluminium-based hardeners were higher and resulted in higher viscosity and shorter
    gelation time. Consequently, despite lower formaldehyde emission was recorded, the
    physico-mechanical properties of the resulted particleboard were inferior compared to
    that of ammonium-based hardeners. The best quality particleboard in terms of mechanical,
    physical and formaldehyde emission were obtained from the particleboard made with AS,
    followed by AC.
  5. Abdalla A. Ab. Rashdi, Mohd Sapuan Salit, Khalina Abdan, Megat Mohamad Hamdan Megat
    Fibre reinforced composites have gained use in a variety of applications. The performances of these composites may suffer when the material is exposed to adverse environments for a long period of time. Kenaf fibre reinforced unsaturated polyester composites were subjected to water immersion tests in order to study the effects of water absorption on the mechanical properties. Composites specimens containing (10%, 20%, and 30%) weight percentages of fibre were prepared. Water absorption tests were conducted by immersing these specimens in a distilled water bath at 25oC for four months. The tensile properties of the specimens immersed in water were evaluated and compared with the dry composite specimens. A decrease in the tensile properties of the composites was demonstrated, indicating a great loss in the mechanical properties of the water-saturated samples compared to the dry samples. The percentage of moisture uptake was also increased as the percentage of the fibre weight increased due to the high cellulose content. The water absorption pattern of these composites was found to follow the Fickian behaviour.
  6. Abdu Masanawa Sagir, Saratha Sathasivam
    Adaptive Neuro Fuzzy Inference System (ANFIS) is among the most efficient classification and prediction
    modelling techniques used to develop accurate relationship between input and output parameters in
    different processes. This paper reports the design and evaluation of the classification performances of
    two discrete Adaptive Neuro Fuzzy Inference System models, ANFIS Matlab’s built-in model (ANFIS_
    LSGD) and a newly ANFIS model with Levenberg-Marquardt algorithm (ANFIS_LSLM). Major steps
    were performed, which included classification using grid partitioning method, the ANFIS trained with
    least square estimates and backpropagation gradient descent method, as well as the ANFIS trained with
    Levenberg-Marquardt algorithm using finite difference technique for computation of a Jacobian matrix.
    The proposed ANFIS_LSLM model predicts the degree of patient’s heart disease with better, reliable
    and more accurate results. This is due to its new feature of index membership function that determines
    the unique membership functions in an ANFIS structure, which indexes them into a row-wise vector. In
    addition, an attempt was also done to specify the effectiveness of the model’s performance measuring
    accuracy, sensitivity and specificity. A comparison of the two models in terms of training and testing
    with the Statlog-Cleveland Heart Disease dataset have also been done.
  7. Abdu Masanawa Sagir, Saratha Sathasivam
    Medical diagnosis is the process of determining which disease or medical condition explains a person’s determinable signs and symptoms. Diagnosis of most diseases is very expensive as many tests are required for predictions. This paper aims to introduce an improved hybrid approach for training the adaptive network based fuzzy inference system (ANFIS). It incorporates hybrid learning algorithms least square estimates with Levenberg-Marquardt algorithm using analytic derivation for computation of Jacobian matrix, as well as code optimisation technique, which indexes membership functions. The goal is to investigate how certain diseases are affected by patient’s characteristics and measurement such as abnormalities or a decision about the presence or absence of a disease. In order to achieve an accurate diagnosis at this complex stage of symptom analysis, the physician may need efficient diagnosis system to classify and predict patient condition by using an adaptive neuro fuzzy inference system (ANFIS) pre-processed by grid partitioning. The proposed hybridised intelligent technique was tested with Statlog heart disease and Hepatitis disease datasets obtained from the University of California at Irvine’s (UCI) machine learning repository. The robustness of the performance measuring total accuracy, sensitivity and specificity was examined. In comparison, the proposed method was found to achieve superior
    performance when compared to some other related existing methods.
  8. Abdul Jalil Nordin, Suraini Mohd Saini, Hairil Rashmizal Abdul Razak, Noraini Abdul Rahim
    The purpose of this article is to demonstrate the appearance of active TB lymphadenitis using multimodality imaging apparatus. Multi-modality diagnostic imaging tools, including chest radiograph, Ultrasound (US), Computed Tomographic Scan (CT), Magnetic Resonance Imaging (MRI), and integrated 18F-FDG Positron Emission Tomography/CT examination, were performed to demonstrate TB lymphadenitis in the neck and superior mediastinum of a 26 year old female patient. There was widening of superior mediastinum on chest radiograph. Meanwhile, the ultrasound carried out detected superficial cystic lesions in the cervical region. The MRI found multiple gadolinium enhanced cervical and mediastinal lymphadenophaties. Contrast enhanced CT found heterogeneous enhancing lymphadenopathies in the same anatomical region. FDG PET/CT demonstrated a high metabolic activity in all lesions, as demonstrated by conventional imaging
    modalities. Mycobacterium tuberculosis was isolated from 1ml aspirate using US guidance. Post treatment FDG PET CT scan demonstrated a complete metabolic remission of active lesions FDG PET CT can be used to demonstrate metabolic activity of active TB lesions in addition to guide clinicians in treating TB lesions.
  9. Abdul Malek Ya’acob, Azhar Abu Bakar, Hanafi Ismail, Khairul Zaman Dahlan
    A hybrid composite consisting of untreated kenaf fibre and glass fibre was investigated by varying the fibre glass weight ratios and using interply fabrication method. The expected results were to have better composite performance in terms of its toughness and impact strength as a comparison between the hybrid (kenaf/E-glass fibre composites) and E-GF composites alone. For the purpose of this study, all the samples were prepared using typical sample preparation. Results show that the incorporation of E–glass fibre resulted in brittle failure and a higher amount of E-Glass fibre with low percentage of kenaf fibre causing high strength, low ductile, and low toughness behaviours.
  10. Abdul Rahim, M.A., Zahari, S.M., Shariff, S.S.R.
    Parameter estimation in Generalized Autoregressive Conditional Heteroscedastic (GARCH) model has received much attention in the literature. Commonly used quasi maximum likelihood estimator (QMLE) may not be suitable if the model is misspecified. Alternatively, we can consider using variance targeting estimator (VTE) as it seems to be a better fit for misspecified initial parameters. This paper extends the application to see how both QMLE and VTE perform under error distribution misspecifications. Data are simulated under two error distribution conditions: one is to have a true normal error distribution and the other is to have a true student-t error distribution with degree of freedom equals to 3. The error distribution assumption that has been selected for this study are: normal distribution, student-t distribution, skewed normal distribution and skewed student-t. In addition, this study also includes the effect of initial parameter specification.
  11. Abdul Razak, H.R., Azmi, N.A., Vinjamuri, S.
    Positron emission tomography-computed tomography (PET-CT) is a hybrid imaging modality that plays a crucial role in detecting and managing oesophageal cancer. However, not much is known about the clinicians’ perspective on its usage for oesophageal cancer. The aim of this study is to know the perspective of clinicians on the utilisation of PET-CT imaging for oesophageal cancer patients. A total of 73 clinicians with multidisciplinary clinical specialties for oesophageal cancer management were interviewed. All these clinicians had completed a survey consisting of 31 questions on; practicality, clinical efficacy and cost-effectiveness of PET-CT. The survey used Likert-scale to evaluate the responses. In terms of PET-CT practicality and clinical efficacy 39.7% - 43.8% and 47.9% - 83.5% of the sample respectively responded positively while in with regards to cost effectiveness, there was a significant difference from being neutral to having no opinion in 6 out of 9 questions. It was clear from the study that PET-CT has positive impact in the management of oesophageal cancer patients. However, issues related to expertise, availability, staffing and bureaucracy need to be addressed to improve competency and quality of services.
  12. Abdulkareem, Jabir Harna, Umar, Da’u Abba, Gabasawa, Alhassan Idris, Anyika, Chinedum, Nor Rohaizah Jamil
    Multivariate statistical techniques such as principal component analysis (PCA) and cluster analysis (CA) were applied to water quality parameters in order to interpret complex matrices for better assessment of water quality and environmental status of a watershed. A study was conducted to assess water quality and to establish relationship among water quality parameters in Kelantan River basin. Water quality data was obtained from Department of Environment, (DOE) Malaysia from 2005-2014. Multivariate statistical techniques such as principal component analysis (PCA) and cluster analysis (CA) were applied to 15 water quality parameters in order to interpret complex matrices for better assessment of water quality and environmental status of the watershed. From the results, five PCs were extracted which are collectively accountable for controlling approximately 70% of the watershed’s water quality. Results of cluster analysis indicated that three water quality parameters that included total suspended solids, total solids and turbidity control the water quality of the study area. These parameters were allocated into three clusters based on their similarity. The finding of this study will contribute to existing knowledge of the problems associated with water quality in the basin. This information can be put to use by land use managers and policy makers for future planning and development of the watershed.
  13. Abdullah, S., Putra, T.E., Nuawi, M.Z., Nopiah, Z.M.
    This paper presents a new approach to identify fatigue damaging potential locations using the Morlet wavelet coefficients. For solving the subject matter, the 122.4 second SAESUS strain signal was selected for the simulation purpose. As the result, the Morlet wavelet coefficients predicted that the maximum fatigue damage occurs at 40.4 - 42.6 seconds and 67.4 - 70 seconds. For the validation purpose, the Morrow’s fatigue damaging value was calculated and was obtained that the maximum fatigue damage occurs at 0 seconds and 99.7 seconds. The fatigue damaging value at the points was 0.0047 cycles to failure. Since both the plots had similar pattern, the Morlet wavelet coefficients could be used as the early warning of the fatigue damaging potential locations, although the locations were not entirely correct.
  14. Abdur Rahman Muhammad Abdul Majid, Nor Asilah Wati Abdul Hamid, Amir Rizaan Rahiman, Basim Zafar
    Tawaf ritual performed during Hajj and Umrah is one of the most unique, large-scale multi-cultural events in this modern day and age. Pilgrims from all over the world circumambulate around a stone cube structure called Ka’aba. Disasters at these types of events are inevitable due to erratic behaviours of pilgrims. This has prompted researchers to present several solutions to avoid such incidents. Agentbased simulations of a large number of pilgrims performing different the ritual can provide the solution to obviate such disasters that are either caused by mismanagement or because of irregular event plans. However, the problem arises due to limited parallelisation capabilities in existing models for concurrent execution of the agent-based simulation. This limitation decreases the efficiency by producing insufficient frames for simulating a large number of autonomous agents during Tawaf ritual. Therefore, it has become very necessary to provide a parallel simulation model that will improve the performance of pilgrims performing the crucial ritual of Tawaf in large numbers. To fill in this gap between large-scale agentbased simulation and navigational behaviours for pilgrim movement, an optimised parallel simulation software of agent-based crowd movement during the ritual of Tawaf is proposed here. The software comprises parallel behaviours for autonomous agents that utilise the inherent parallelism of Graphics Processing Units (GPU). In order to implement the simulation software, an optimized parallel model is proposed. This model is based on the agent-based architecture which comprises agents having a reactive design that responds to a fixed set of stimuli. An advantage of using agents is to provide artificial anomaly to generate heterogeneous movement of the crowd as opposed to a singular movement which is unrealistic. The purpose is to decrease the execution time of complex behaviour computation for each agent while simulating a large crowd of pilgrims at increased frames per second (fps). The implementation utilises CUDA (Compute Unified Device Architecture) platform for general purpose computing over GPU. It exploits the underlying data parallel capability of an existing library for steering behaviours, called OpenSteer. It has simpler behaviours that when combined together, produces more complex realistic behaviours. The data-independent nature of these agent-based behaviours makes it a very suitable candidate to be parallelised. After an in-depth review of previous studies on the simulation of Tawaf ritual, two key behaviours associated with pilgrim movement are considered for the new model. The parallel simulation is executed on three different high-performance configurations to determine the variation in different performance metrics. The parallel implementation achieved a considerable speedup in comparison to its sequential counterpart running on a single-threaded CPU. With the use of parallel behaviours, 100,000 pilgrims at 10 fps were simulated.
  15. Abdurashid Mamadolimov, Herman Isa, Miza Mumtaz Ahmad, Moesfa Soeheila Mohamad
    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.
  16. Abidin, N. Z., Adam, M. B., Midi, H.
    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.
  17. Abu Bakar, M.A., Ahmad, S., Kuntjoro, W.
    Kenaf fibre that is known as Hibiscus cannabinus, L. family Malvaceae is an herbaceous plant that can be grown under a wide range of weather conditions. The uses of kenaf fibres as a reinforcement material in the polymeric matrix have been widely investigated. It is known that epoxy has a disadvantage of brittleness and exhibits low toughness. In this research, liquid epoxidized natural rubber (LENR) was introduced to the epoxy to increase its toughness. Kenaf fibres, with five different fibre loadings of 5%, 10%, 15%, 20% and 25% by weight, were used to reinforce the epoxy resins (with and without addition of epoxidized natural rubber) as the matrices. The flexural strength, flexural modulus and fracture toughness of the rubber toughened epoxy reinforced kenaf fibre composites were investigated. The results showed that the addition of liquid epoxidized natural rubber (LENR) had improved the flexural modulus, flexural strength and fracture toughness by 48%, 30%, and 1.15% respectively at 20% fibre loading. The fractured surfaces of these composites were investigated by using scanning electron microscopic (SEM) technique to determine the interfacial bonding between the matrix and the fibre reinforcement.
  18. Adib Kabir Chowdhur, Veeramani, Shanmugan
    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.
  19. Adole, Adole Michael, Jamaludin Mohamad Yatim, Suhaimi Abubakar Ramli, Athirah Othman, Norazura Azzmi Mizal
    (Kenaf fibre is a good reinforcement in fibre polymer composites due to its high strength
    and elastic modulus, high stiffness, low density, low cost and eco-efficient, less health
    hazards, renewability, good mechanical and thermal properties, and biodegradability. It is
    traditionally used for rope, twine, fish net and sacking materials. Recently, it was observed
    that kenaf fibre had huge potentials to replacing synthetic fibre in composites due to the
    rising environmental and ecological issues, thus this awareness has motivated efforts for
    the advancement of new innovative bio-based composites incorporating kenaf fibre for
    various end-use structural applications. This paper presents an overview of the development
    made so far in the area of kenaf fibre and its composites in terms of chemical and microstructural
    properties, mechanical properties, dimensional stability, thermal stability, product
    development and application. Some fundamental issues and suggestions for further research
    in this area are also discussed.
  20. Agung Efriyo Hadi, Mohd. Sapuan Salit, Megat Mohd. Hamdan Megat Ahmad, Khairul Zaman Hj Mohd. Dahlan, Mustofa Usman
    The physical properties by natural fibre have a great importance, specifically in the structural of natural fibre which reinforces matrix. Response surface methodology with Box-Behnken (BB) design of experiment was utilized to study water absorption and melt flow index (MFI) of abaca fibre reinforced high impact polystyrene (HIPS) composites. The design utilizes fraction of weight abaca fibre, maleic anhydride (MAH), and impact modifier to develop models for characteristic behaviours of water absorption and MFI of composites. Abaca fibre reinforced high impact polystyrene (HIPS) composites were produced with different fibre loadings (30, 40, and 50 wt%), different compositions of coupling agent, maleic anhydried (MAH) (1, 2, and 3 wt%) and different compositions of impact modifier (4, 5, 6 wt%). The individual optimum of water absorption was found when loading abaca fibre close to 34.61 wt%, maleic anhydride 1 wt%, and impact modifier 4.01 wt%. The individual optimum of melt flow index dealt with loading abaca fibre 36.71 wt%, maleic anhydride 3 wt% and impact modifier 4.02 wt%. Meanwhile, the optimum condition for water absorption of abaca fibre reinforced HIPS composites was followed by a decreasing trend of the value of melt flow index.
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