Displaying publications 1 - 20 of 811 in total

  1. Anisuzzaman, S.M., Krishnaiah, D., Bono, A., Lahin, F.A., Suali, E., Zuyyin, I.A.Z.
    In this study, simulation and optimisation of the purification of bioethanol from an azeotropic mixture was done using the Aspen HYSYS and the Response Surface Methodology (RSM), respectively, to achieve an acceptable bioethanol content with minimal energy use. The objective of this study is to develop the simulation process of bioethanol production from a fermentation effluent. Additionally, the effects of parameters such as solvent temperature, number of entrainer feed stage, mass flow rate and third components of the process for production of bioethanol were studied. As bioethanol is a product of biofuel production, the main challenge facing bioethanol production is the separation of high purity ethanol. However, the separation of ethanol and water can be achieved with the addition of a suitable solvent such as 1,3-butylene glycol (13C4Diol), mixture 13C4Diol and ethylene glycol (EGlycol) and mixture 13C4Diol and glycol ethyl ether (DEG) in the extractive distillation process. For the 13C4Diol mixture, the temperature of entrainer is 90oC with 1500 kg/hr of entrainer rate, while the number of entrainer feed stage is one. The optimum conditions for mixture 13C4Diol and EGlycol require a temperature of entrainer of 90.77oC with an entrainer rate of 1500 kg/hr, while the number of entrainer feed stage is one. Lastly, for optimum conditions for the mixture 13C4Diol and DEG, the temperature of entrainer should be 90oC with an entrainer rate of 1564.04 kg/hr, while the number of entrainer feed stage is one. This study shows that process simulation and optimisation can enhance the removal of water from an azeotropic mixture.
  2. Rohayu Haron Narashid, Ruslan Rainis, Zulyadini A. Rahaman
    Rainfall is one of the microclimatic variables that vary with space. The changes in vegetation characteristics may influence the microclimate elements. To demonstrate rainfall variation due to vegetation, the relationship between rainfall and vegetation should be spatially investigated over a local scale. This paper aims to explore the impact of vegetation on local variations of rainfall based on Geographically Weighted Regression (GWR) approach. The global and local relationship between rainfall and the extracted Normalized Difference Vegetation Index (NDVI) of Landsat 7 ETM+ are quantitatively estimated in 2000 and 2011 within the northern and east coast regions of the Peninsular Malaysia. Based on 277 rainfall stations, the Moran’s Index (Moran’s I) spatial autocorrelation and Ordinary Least Square (OLS) - GWR methods were applied to analyse the rainfall spatial patterns and to determine rainfall spatial variation, respectively. It was found that, the rainfall spatial patterns exhibit small clustering patterns which leads to non-stationarity. This indicator supports the use of local regression approach in exploring the variation of rainfall due to vegetation. The R-Squared (R2) from GWR (0.51 and 0.75) significantly improved the R2 from OLS (0.01 and 0.04) for both years. The approach of GWR in the relationship between rainfall and vegetation provides findings on rainfall spatial variation on a local scale.
  3. Mohd Aizam Talib, Nor Asiah Muhamad, Zulkurnain Abdul Malek
    Preventive tests and diagnosis of in-service power transformer are important for early fault prediction and increased reliability of electricity supply. However, some existing diagnostic techniques require transformer outage before the measurement can be performed and need expert knowledge and experiences to interpret the measurement results. Other measurement techniques such as chemical analyses of insulating oil may cause significant variance to measurement results due to different practices in oil sampling, storage, handling and transportation of oil. A cost-effective measuring technique, which is simple, providing fast and an accurate measurement results, is therefore highly required. The extended application of Polarisation and Depolarisation (PDC) measurement for characterisation of different faults conditions in-service power transformer has been presented in this paper. Earlier studies on polarisation and depolarisation current of oil samples from in-service power transformer shows that depolarisation has provided significant information about the change of material properties due to faults in power transformer. In this paper, a new approach based on Depolarisation Current Ratio Index (DRI) was developed for identifying and classifying different transformer fault conditions. The DRI at time interval of 4s to 100s was analysed and the results show that DRI of depolarisation current between 5/100s and 10/100s provides higher correlation on the incipient faults in power transformer.
  4. Qiwei, Zhang, Mohamad Faiz Zainuddin, Ahmad Fahad Ahmad, Obays, Susan Jabbar, Zulkifly Abbas
    This study attempts to develop a soil moisture measurement system with a monopole antenna sensor, mini-VNA Tiny and a mobile phone respectively. The mini-VNA Tiny is a compact vector network analyzer (VNA) with a USB connection to a smartphone or a tablet. There are 17 sets of data which have been collected from 15 different spots with varying soil moisture content. The actual moisture content on site was collected from TRIME-PICO 64/32 sensor. Upon collection, it was necessary to calibrate the resistance obtained from the mini-VNA between 1 MHz and 3 GHz. The data obtained from the study shows that the resonances of the antenna resistance shift to the left on the frequency spectrum as moisture content increases. A linear model relating the resistance and actual moisture content was developed from this study with coefficient of determination (R2) value of 0.723 at 13 MHz. This value is much less than the anticipated R2 = 0.95 for accurate measurement of soil moisture with monopole antenna at microwave frequency. This could be due to the 0.60 cm thickness of the monopole antenna which may not be suited for soil moisture measurement. Nonetheless, this study demonstrates the potential application of an inexpensive and portable mini-VNA Tiny and smartphone system for sensing applications.
  5. Syahrizal Salleh, Zulkifli Abd Majid
    An AC to DC voltage rectifier and its respective regulator were designed and integrated on a 0.25μm CMOS process. Its input impedance was measured along with the regulated DC output. Input impedance of a series of rectangular coil microstrip antenna on FR4 PCB with outer dimension of 78mm x 41mm was measured. The positive reactance of the antenna was matched at resonance with negative reactance of the integrated rectifier and regulator with addition of external capacitor. Relationship between incidental electromagnetic field in A/m at the coil microstrip antenna all the way to the rectified DC voltage at the output of the regulator is presented. In the context of wireless power transfer, this work focuses on the remote unit that absorbs electromagnetic field generated by another system and converts the energy into DC supply voltage for remote device
  6. Azizul Isha, Nor Azah Yusof, Musa Ahmad, Dedy Suhendra, Wan Md. Zin Wan Yunus, Zulkarnain Zainal
    An artificial neural network (ANN) was applied for the determination of V(V) based on immobilized fatty hydroxamic acid (FHA) in poly(methyl methacrylate) (PMMA). Spectra obtained from the V(V)-FHA complex at single wavelengths was used as the input data for the ANN. The V(V)-FHA complex shows a limited linear dynamic range of V(V) concentration of 10 - 100 mg/ L. After training with ANN, the linear dynamic range was extended with low calibration error. A three layer feed forward neural network using backpropagation (BP) algorithm was employed in this study. The input layer consisted of single neurons, 30 neurons in hidden a layer and one output neuron was found appropriate for the multivariate calibration used. The network were trained up to 10000 epochs with 0.003 % learning rate. This reagent also provided a good analytical pedormance with reproducibility characters of the method yielding relative standard deviation (RSD) of 9.29% and 7.09% for V(V) at concentrations of 50 mg/ L and 200 mg/ L, respectively. The limit of detection of the method was 8.4 mg/ L.
  7. Zulkarnain Hassan
    Fine resolution (hourly rainfall) of rainfall series for various hydrological systems is widely used. However, observed hourly rainfall records may lack in the quality of data and resulting difficulties to apply it. The utilization of Bartlett-Lewis rectangular pulse (BLRP) is proposed to overcome this limitation. The calibration of this model is regarded as a difficult task due to the existence of intensive estimation of parameters. Global optimization algorithms, named as artificial bee colony (ABC) and particle swarm optimization (PSO) were introduced to overcome this limitation. The issues and ability of each optimization in the calibration procedure were addressed. The results showed that the BLRP model with ABC was able to reproduce well for the rainfall characteristics at hourly and daily rainfall aggregation, similar to PSO. However, the fitted BLRP model with PSO was able to reproduce the rainfall extremes better as compared to ABC.
  8. Gumgaro Simon, Peter Buba, Razali Adul Hamid, Zuhaili Mohamad Ramly
    Notably in the construction industry, procurement is evidently important and cannot be played down because it constitutes every phase of a project delivery system. The low-bid system has remained the most popular procurement system globally. In Nigeria, it lacks transparency and accountability. Therefore, the Nigerian Procurement system has shown a need to be stabilised by shifting risk and control to the expert who has the duty to act in the client’s best interest by adopting “Best Value Performance Information Procurement System (BVPIPS)” in contractor selection. This paper aims at identifying factors that can hinder the implementation of this innovative procurement system and their relative influence. A total 314 questionnaires were distributed to 5 construction industry professionals in Nigeria they are: Architects, Quantity Surveyors, Civil Engineers, Builders and Services Engineers. The data collected were presented and analysed using: cross tabulation, exploratory factor analysis and mean score ranking using Statistical Package for Social Sciences (SPSS) version 24 and Microsoft Excel respectively. Likert scaling was used to measure the level of agreement of the respondents. The paper found out that the social factor, political factor, procurement environment factors and the cultural factor in the construction industry ranked 1, 2, 3 and 4 respectively and which factors have a very strong relative influence on hindering the implementation of BVPIPS in the Nigerian construction industry. The implication of this study is, to help construction practitioners, researchers, academics, industry players, and other stakeholders to look into the significant issues that can hinder the implementation of PIPS in Nigeria and make better the delivery of projects in the construction industry. Therefore, these factors identified should be considered and precautionary measures taken when implementing BVPIPS in the Nigerian construction industry so as to accommodate innovative approaches such as BVPIPS to improve project delivery in Nigeria.
  9. Nicky Rahmana Putra, Mohd Azizi Che Yunus, Muhammad Syafiq Hazwan Ruslan, Fadillah Nur Idrus, Zuhaili Idham
    The objective of this study was to compare the extraction of peanut skin using supercritical carbon dioxide extraction and soxhlet extraction in terms of oil yield and catechin. For supercritical fluid extraction, the temperatures used were 40 and 70°C, while pressure used was 10 and 30 MPa, the flow rate was CO2 3 mL/min, and the concentration of co-solvents was 0 and 5%. Meanwhile, for soxhlet extraction, the extraction time was 6 hr with ethanol, hexane and water as the solvents. The results showed that soxhlet extraction gave the highest yield of extract (36.282%) using ethanol as solvent as compared with supercritical CO2 extraction (15.47%) at pressure 30 MPa, temperature 70°C and 5% concentration of co-solvent. This study reveals that the extracts from SC-CO2 extraction yielded the highest amount of catechin (208.73 µg/g sample) compared with that yielded in the soxhlet extraction (42.24 73 µg/g sample) with distilled water as a solvent analysed with High Performance Liquid Chromatography (HPLC).
  10. Mohamad Radhi Amonodin, Rohasliney Hashim, Mohammad Noor Amal Azmai, Zarul Hazrin Hashim
    This study was conducted to evaluate the physical habitat of spawning areas for Thynnicthys thynnoides (T. thynnoides) in the Rui River, Gerik, Perak. Five sampling sites of Rui River’s floodplain were chosen. Sampling was conducted between May and October 2015 by using a visual-based habitat assessment developed for Rapid Bioassessment Protocols for Use in Streams and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates and Fish. This study showed that T. thynnoides still migrated to the upper stream of Rui River during spawning season mainly in August. Habitat assessment scoring indicated that the physical habitat structure of Rui River fell into a suboptimal category, which was most likely able to support fish populations and thus providing a suitable habitat for T. thynnoides during the spawning season. Conclusively, it was observed that the T. thynnoides population was dependent on environmental conditions.
  11. Resdiansyah, Amidah Mohd Ujang, Zarinah Zaini
    Malaysia has over 5 million hectares of land planted with palm oil, divided almost equally between peninsula Malaysia and East Malaysia. This paper presents a laboratory evaluation of the performance of the waste product palm kernel shell (PKS) in creating plant-based asphalt concrete (bio-asphalt concrete). PKS aggregate partially replaced granite aggregate in preparing the mixes (10%, 30%, and 100%) in the range of 5mm-14mm in ACW 14 mixed with 5% to 7% of bitumen content. 35 blows and 50 blows compaction of mixes was used to evaluate the potential of palm kernel shells in the preparation of bitumen to deal with light to medium traffic. Results showed that PKS aggregate can be used up to 30% PKS replacement for the light traffic design and only 10% PKS replacement was potential to be used in medium traffic design.
  12. Ramadas, A., Kandiah, M., Jabbar, F., Zarida, H.
    At least 6 million deaths occurred worldwide are due to cancer and this figure is expected to rise to
    15 millions by the year 2020. Colorectal cancer is among the most commonly occurring cancers
    both globally and in Malaysia. Numerous studies have shown significant relationships between
    various dietary components and the risks for colorectal cancer. Meanwhile, several theories have
    been suggested as etiological explanations, one of which is the influence of dietary factors on the
    cell proliferation rate. A higher cell proliferation rate is statistically associated with increased risk
    of colorectal cancer. However, evidence of a significant relationship between diet and colorectal
    adenomas, a potential precursor for colorectal cancer, remains insufficient. Colorectal adenomas or
    polyps are vital in their relationship with colorectal cancers as almost 70% of all colorectal cancers
    are developed from these polyps. Studying the modifiable risk factors related to polyps will provide
    an opportunity for the prevention of colorectal cancer even before it develops. This paper reviews
    the available evidence linking dietary factors with the risk for colorectal adenomas. As the numbers
    of published studies are limited, of which most are concentrated in Western countries, there is a
    need for epidemiological studies in Malaysia to strengthen the evidence of a relationship between
    diet and colorectal adenomas.
  13. Siregar, J.P., Sapuan, S.M., Rahman, M.Z.A., Zaman, H.M.D.K.
    A study on the effects of alkali treatment and compatibilising agent on the tensile properties of pineappleleaf fibre (PALF) reinforced high impact polystyrene (HIPS) composite is presented in this paper. Thetensile properties of natural fibre reinforced polymer composites are mainly influenced by the interfacialadhesion between the matrix and the fibres. In this study, several chemical modifications were employedto improve the interfacial matrix-fibre bonding and this resulted in the enhancement of tensile propertiesof the composites. In this study, the surface modification of pineapple fibre with alkali treatments andcompatibilizer were used to improve the adhesion between hydrophilic pineapple fibre and hydrophobicpolymer matrix. There are two concentrations of NaOH treatments and compatibilizer used in this study,namely, 2 and 4 wt. %. The results show that the alkali treated fibre and the addition of compatibilisingagent in PALF/HIPS composites have improved the tensile strength and tensile modulus of the composites.
  14. Nur Zulaikhah Nadzri, Mohammad Hamiruce Marhaban, Siti Anom Ahmad, Asnor Juraiza Ishak, Zalhan Mohd Zin
    Referring to the existing model that considers the image boundary as the image background,
    the model is still not able to produce an optimum detection. This paper is introducing
    the combination features at the boundary known as boundary components affinity that is
    capable to produce an optimum measure on the image background. It consists of contrast,
    spatial location, force interaction and boundary ratio that contribute to a novel boundary
    connectivity measure. The integrated features are capable to produce clearer background
    with minimum unwanted foreground patches compared to the ground truth. The extracted
    boundary features are integrated as the boundary components affinity. These features were
    used for measuring the image background through its boundary connectivity to obtain the
    final salient object detection. Using the verified datasets, the performance of the proposed
    model was measured and compared with the 4 state-of-art models. In addition, the model
    performance was tested on the close contrast images. The detection performance was
    compared and analysed based on the precision, recall, true positive rate, false positive
    rate, F Measure and Mean Absolute Error (MAE). The model had successfully reduced
    the MAE by maximum of 9.4%.
  15. Sallehan Ismail, Zaiton Yaacob
    The development of a new, low-cost building material that is composed of non-fired, pressed laterite bricks incorporating oil palm empty fruit bunches (OPEFB) fibre was investigated in this study. The main aim of this research was to study the physical and mechanical properties of laterite brick reinforced with OPEFB fibre, including dimensions, weight, density, water absorption and compressive strength. The tests were carried out according to BS 3921:1985 for water absorption and compressive strength tests. The mix proportion of the control bricks was 70% soil, 24% sand, and 6% cement. Meanwhile, the OPEFB fibre contents ranged from 1% to 5% by weight of cement. The specimens were taken from a total of 120 bricks. The findings withdrawn from this research were: firstly, the density of laterite bricks was decreased with the increase in the OPEFB fibre content of the bricks. Secondly, it was found that the addition of the OPEFB fibres improved the compressive strength of the bricks, and the maximum compressive strength determined in this study for bricks was with 3% fibre content. Finally, the water absorption results indicated a small increase in water absorption with the increase in the OPEFB fibre content in laterite bricks.
  16. Chew BH, Lee PY, Mastura I, Cheong AT, Sri Wahyu T, Zaiton A
    An audit of Diabetes Control and Management-Diabetes Registry Malaysia (ADCM-DRM) was started to monitor the provision of diabetes care in the country. A total of 20,646 patients were registered in the registry until 31st December 2008. This report set out to determine the Type 2 diabetes controls and treatment profiles of these cohorts of patients. This was a registry-based observational study conducted from May to December, 2008. An online standard case record form was available for site data providers to register their diabetic patients aged 18 years old and above annually. Demographic data, diabetes duration, treatment modalities, as well as various risk factors and diabetes complications were reported. Data were analyzed using Data Analysis and Statistical Software (Stata) version 9. A total of 81 centres, 6 of which were hospitals, participated in this registry until 31st December 2008, contributing a total of 20646 patients. A majority of them (99.2%) had Type 2 diabetes mellitus. The mean HbA1c was 8.0% (SD 2.10), with 30.1% and 17.9% of the patients who attained HbA1c < 7% and HbA1c < 6.5%, respectively. Metformin was prescribed more than sulfonylurea while only 11% had insulin. A review of the diabetic care policy and strategies in the primary health care clinics is needed to implement a more effective treatment of diabetes in this country.
  17. Suhaini Raeze, Alawi Sulaiman, Azhari Samsu Baharuddin, Mohd Noriznan Mokhtar, Zainuri Busu
    In this study, residual oil from oil palm decanter cake (OPDC) was recovered using n-hexane through Soxhlet extraction process. The residual oil recovered was analysed for its physical and chemical properties. The oil content, moisture, Free Fatty Acid (FFA), Peroxide Value (PV), Iodine Value (IV), Deterioration of Bleachability Index (DOBI) and carotene were measured as 15.43±0.45% (dry), 70.96±0.14%, 6.42±0.11%, 4.37±0.04 meq/kg, 53.28±0.02 g/100 g, 1.93±0.03 and 833.20±39 ppm respectively. The results showed that its fatty acid composition, carotene and IV were comparable with the Malaysian Palm Oil Board (MPOB) standard for crude palm oil (CPO), whilst the properties of the other value had slightly exceeded due to oxidation during the extraction process.
  18. Nurul Husna Kamarudin, Nor Azlina A. Rahman, Zainul Ibrahim Zainuddin
    The presence of imaging technologies in Malaysia needs to be supported by homegrown research to optimize and tailor their usage for local benefits. Research done elsewhere may not be applicable to local situations. This study investigates the contribution of researches by Malaysian academicians and service providers to the field of medical imaging, as evident in the Malaysian Citation index (MyCite) database. Bibliometric and thematic analyses were performed on publications featured in the database from 2006 to 2016. The bibliometric analysis provided information on the affiliation of the authors, their professional backgrounds, types of studies, and the journals involved while the thematic analysis identified the themes and sub-themes of identified articles. The study found that Malaysians contributed 54.1% of the publications, followed by non-Malaysians (41.8%) and collaboration authors (4.1%). Researchers were mostly from university-based and hospital university-based institutions. The thematic analysis presented that 42.9% of articles were classified under clinical themes. The results also suggested that the current trends of research in medical imaging are focused on topics involving clinical and modality, and only a few patient-centered researches. This is an indication that more researches that are relevant to local practices and needs are required as this will strengthen the medical imaging practice in the country.
  19. Hussin, H., Zainudin, M.F.
    Negative bias temperature instability (NBTI) is a common phenomenon in a p-channel MOSFET device
    under a negative gate-to-source voltage at a high stress temperature. This paper presents the NBTI
    characterisation based on different analysis methods and stress conditions on p-MOSFET devices. The
    atomic hydrogen concentration is probed at interface, Poly-Si and channel of p-MOSFET under study
    using SILVACO TCAD tool. In addition, the behaviour of the permanent and recoverable component
    was investigated based on AC stress at different stress conditions using Modelling Interface Generation
    (MIG) tool. The results show that increases in temperature, negative voltage stress gate and decreases
    in frequency increase the threshold voltage shift, thus enhancing NBTI degradation.
  20. Ahmad, M.B., Hashim, K.B., Mohd Yazid, N., Zainuddin, N.
    In this work, hydrogels were prepared from carboxymethyl cellulose (CMC) and 1-vinyl-2-pyrrolidone(VP) by Electron Beam irradiation in the presence of N,N'-methylenebisacrylamide (BIS) as a crosslinkingagent. The parameters studied include stirring time and percentage of crosslinking agent. Hydrogels werecharacterized using Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy(SEM). VP and BIS were found be effective as reinforcement materials to improve the properties ofCMC. Meanwhile, the optimum conditions were 5% BIS and 3 hours of stirring time. The gel fractionincreased when irradiation dose was increased. FTIR confirmed the crosslinking reaction between CMCand VP after the irradiation process by using BIS as the crosslinking agent. TGA thermograms showedchanges in the thermal properties of CMC-VP hydrogels in the presence of different amounts of BIS.
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