Displaying publications 1 - 20 of 811 in total

  1. Zurriati Mohd Ali, Wahyu Kuntjoro, Wirachman Wisnoe, Rizal Effendy Mohd Nasir, Noor Iswadi Ismail
    The blended wing body (BWB) aircraft has a unique design. The main body and wing of BWB are
    merged to increase the lift force on the aircraft. However, BWB has poor stability arising from the absence of the tail. Hence, a small horizontal stabilizer called as canard has been incorporated in front of the main wing to improve BWB’s stability. Computational Fluid Dynamics (CFD) simulations conductedm to obtain the aerodynamics parameters of the BWB i.e. lift, drag and moment coefficients, showed that overall, the canard is beneficial to the BWB aerodynamics performance.
  2. Zurina Zainal Abidin, Zalini Yunus, Markx, Gerard H.
    The dielectrophoretic (DEP) separation of cell, using microelectrodes structure, has been limited to small scale due to size of the substrate. This work was carried out to extend the capability of microelectrodes system by orientating the microelectrodes in three dimensions (3-D) for larger scale dielectrophoretic separation of microorganism. The designed 3-D separation chamber consists of microelectrodes on two opposing walls. Based on the FEMLAB simulation, the electric field was seen to be generated across the chamber, rather than between adjacent electrodes in the same plane like in the small scale system. This configuration led to a stronger electric field in the bulk medium. The experimental results showed that the 3-D microelectrodes chamber behaved similar to the system with microelectrodes on one wall. The effects of the main parameters such as voltage, frequency and flow rates were similar to that of the systems with all the electrodes on one wall, but on the overall, capture more cells. A gap size between 250 – 500 μm resulted in an electric field which is strong enough to hold cells while giving a reasonable cross sectional area at the same time. Although there is some improvement achieved by 3-D system, it is still not very much, as compared to the small scale system.
  3. Zuraini Zainol, Azizi Ali, Mohd Safuan Che Din, Mohd Fadzil Akhir, Zainudin Bachok, Ahmad Ali
    Degradation of coastal water quality is one of the major concern in the Malacca Strait since this area is one of the most important fishing ground in Malaysia. Despite being great in the fishery industry, Malacca and Negeri Sembilan somehow recorded the lowest marine fishes landing, which raises a question about dynamics of this area. It is therefore, a preliminary study of the physical properties and nutrient concentrations carried out from 27 March to 4 April 2016 at the coastal water off the southern west coast of Peninsular Malaysia, specifically at Pulau Besar, Malacca and Tanjung Tuan, Negeri Sembilan. Data for temperature, salinity, and dissolved oxygen (DO) was acquired by using Conductivity, Temperature, and Depth (CTD) probe. Meanwhile, nutrient concentrations determination in this study was done by using a Westco Smartchem 200 Discrete Analyser, according to the procedure adopted from United States Environmental Protection Agency (USEPA). In general, results of this study indicated the coastal stations were characterised with cooler, less saline, and high DO waters than stations away from coast. Large sea surface heating and weak winds were determined as the causative factors affecting dynamics of water column at the study area. At nearshore area, temperature, salinity, and DO variability were modulated by degree of freshwater intrusion. High nutrient concentrations at the stations closer to the coast was believed to be associated with river outflow, which acted as the main source of nutrients supply in this area. Comparison to previous study had shown that nutrient concentrations in this research were low, which could contribute to an insight on declining marine fish catches in these two states. With regard to Malaysian Marine Water Quality Criteria and Standard (MWQCS), mean nutrient concentrations at the study area were in Class 1, which are suitable for marine parks and marine protected areas conservation. Regardless of limited scope, the outcome of this study is believed to be a good baseline reference for future studies seeking to understand coastal dynamics.
  4. Zuraidah Salleh, Nik Rozlin Nik Masdek, Koay Mei Hyie, Syarifah Yunus
    Kenaf fibre is one of the natural fibers that has received much attention of many researchers because of its good properties and flexible use. Kenaf fibre composites have been proposed as interior building materials. In this study, the recycling effect on the kenaf PVC wall panel is focused. The main objective of this study is to determine the mechanical properties of different types of kenaf PVC wall panels. The samples were formulated based on the first and third recycling process. The specimens were subjected to several types of tests, namely, tensile, izod impact, flexural and hardness based on ASTM D3039, ASTM D256, ASTM D7264 and ASTM D785, respectively. The results indicate that the mechanical properties of the third recycled kenaf PVC wall panel product is better than the virgin and first recycled specimen. This shows that the recycling process enhances the mechanical properties of the product. On the other hand, the hardness of the specimen decreases after first recycling due to the reheating effect.
  5. Zulkifli, C.Z., Noor, N.N.
    This paper presents the technology of Active Radio Frequency Identification (RFID) and Wireless Mesh
    Sensor Network (WMSN) that will be used in agriculture. In this paper, ZigBee technology platform is
    applied in 2.45 GHz and active RFID to sustain the WSN by developing a fully automated IoT solution
    in agriculture for irrigation system. The system includes a plurality of sensor nodes installed in a crop
    field sending an ID, which are embedded sensor and WSN that work on ZigBee 2.4 GHz platform. The
    ID was sent to act as a signal of soil in dry condition of a specific area to a reader at base station. The
    pump stations will use information from base station to sprinkling water in the specific area of the dry
    state automatically. The automatic control system is very practical in agriculture but most of it is based
    on schedule and timer regardless of soil condition and temperature. Therefore, wireless automated
    irrigation system for efficient water use and production is proposed.
  6. Zulkifli Yusop, Lloyd Ling
    The selection of curve number to represent watersheds with similar land use and land cover is often subjective and ambiguous. Watershed with several soil groups further complicates curve number selection process while wrong curve number selection often produces unrealistic runoff estimates. The 1954 simplified Soil Conservation Services (SCS) runoff model over-predicted runoff with significant amount and further magnified runoff prediction error toward higher rainfall depths in this study. The model was statistically insignificant with the rejection of two null hypotheses and paved the way for regional model calibration study. This paper proposes a new direct curve number derivation technique from the given rainfall-runoff conditions under the guide of inferential statistics. The technique offers a swift and economical solution to improve the runoff prediction ability of the SCS runoff model with statistically significant results. A new rainfall-runoff model was developed with calibration according to the regional hydrological conditions. It out-performed the runoff prediction of the simplified SCS runoff model and the asymptotic runoff model. The derived curve number = 89 at alpha = 0.01 level. The technique can be adopted to predict flash flood and forecast urban runoff.
  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. Zulfadhli Mustafa Albakri, Muhamad Saufi Mohd Kassim, Ahmad Fikri Abdullah, Hazreen Haizi Harith
    In order to ensure the optimum quality of palm oil, oil palm fruit needs to be harvested at the optimum maturity to avoid free fatty acid (FFA) accumulation. The high content of FFA not only reduces the quality of palm oil but also increases the refining cost. Optimum maturity based on plantation standard operating procedure (SOP) is determined by identifying the tree with loose fruit on the ground. The matured bunch is further identified based on the colour of the bunch. This paper presents a research work on formulation and validation of mathematical equations to estimate the maturity stages (age in weeks) of fresh fruit bunch (FFB) based on FFB position in oil palm phyllotaxis (spiral leaves arrangement) as an additional feature to confirm the maturity level of oil palm FFB. Regression analysis showed that the proposed method was able to estimate the maturity stages of oil palm FFB with the coefficient of determination R2 = 0.9 and a root mean square error (RMSE) of 1.58 weeks. The FFB yield estimation model and harvesting can be created based on the extracted data using the formula which will help in the planning of harvesting operation. Plantation manager can use this information to generate yield variability map and estimate the appropriate number of workers and machine. Planned harvesting operation can save a significant amount of time in site harvesting operation.
  9. Zulfa, A.W., Norizah, K.
    The mangrove forest ecosystem acts as a shield against the destructive tidal waves, preventing the coastal areas and other properties nearby from severe damages; this protective function certainly deserves attention from researchers to undertake further investigation and exploration. Mangrove forest provides different goods and services. The unique environmental factors affecting the growth of mangrove forest are as follows: distance from the sea or the estuary bank, frequency and duration of tidal inundation, salinity, and composition of the soil. These crucial factors may under certain circumstances turn into obstacles in accessing and managing the mangrove forest. One effective method to circumvent this shortcoming is by using remotely sensed imagery data, which offers a more accurate way of measuring the ecosystem and a more efficient tool of managing the mangrove forest. This paper attempts to review and discuss the usage of remotely sensed imagery data in mangrove forest management, and how they will improve the accuracy and precision in measuring the mangrove forest ecosystem. All types of measurements related to the mangrove forest ecosystem, such as detection of land cover changes, species distribution mapping and disaster observation should take advantage of the advanced technology; for example, adopting the digital image processing algorithm coupled with high-resolution image available nowadays. Thus, remote sensing is a highly efficient, low-cost and time-saving technique for mangrove forest measurement. The application of this technique will further add value to the mangrove forest and enhance its in-situ conservation and protection programmes in combating the effects of the rising sea level due to climate change.
  10. Zuber, M., Hisham, M.S.B., Nasir, N.A.M., Basri, A.A., Khader, S.M.A.
    This paper is a Computational Fluid Dynamics (CFD) study of the performance of a jet engine annular
    combustor that was subjected to various loading conditions. The aim is to comprehend the effect of
    various genuine working conditions on ignition and emission performance. The numerical models utilized for fuel ignition is the feasible k-ω model for turbulent stream, species transport (aviation fuel and air) with eddy-dissipation reaction modelling and pollution model for nitrogen oxides (NOX) emission. The results obtained confirm the findings described in the literature.
  11. Zubaida Hassan, Shuhaimi Mustafa, Raha Abdul Rahim, Nurulfiza Mat Isa
    Human breast milk microbiota is essential for infant immune system development, maturation and
    protection against infection. However, there is scarce information on the fluid’s microbiological
    composition from Malaysia. The objective of the study was to isolate, identify and characterise commensal
    bacterial population present in human breast milk from Malaysia. One hundred bacteria were isolated
    from the human breast milk of healthy lactating women (n=30). After preliminary screening, 20 isolates
    were characterised using both phenotypic and molecular techniques. The results indicated that most
    frequently identified bacteria in this study were E. faecalis and S. hominis. These organisms alongside E.
    cloacae were all metabolised D-Maltose, Sucrose, D-Turanose, α-D-Glucose, D-Fructose, D-Mannose,
    D-Galactose, D-sorbitol and D-Mannitol and were able to grow at pH 5 and 6, 1% sodium lactate, 1%,
    2% and 8% NaCl. BLAST showed over 99% similarity to those deposited in Genbank. Phylogeneticrelatedness
    was depicted using neighbour-joining method and had two clades with 100% bootstrap. These
    findings provided insight into the nature, characteristics and also phylogenetic-relatedness of bacteria
    present in human milk from Malaysia. Isolation and identification of commensal bacteria from human
    milk are considered the first step for future studies on the benefit of these organisms towards human health.
  12. Zin, M.H., Abdan, K., Norizan, M.N., Mazlan, N.
    The main focus of this study was to obtain the optimum alkaline treatment for banana fibre and the its effect on the mechanical and chemical properties of banana fibre, its surface topography, its heat resistivity, as well as its interfacial bonding with epoxy matrix. Banana fibre was treated with sodium hydroxide (NaOH) under various treatment conditions. The treated fibres were characterised using FTIR spectroscopy. The morphology of a single fibre observed under a Digital Image Analyser indicated slight reduction in fibre diameter with increasing NaOH concentration. The Scanning Electron Microscope (SEM) results showed the deteriorating effect of alkali, which can be seen from the removal of impurities and increment in surface roughness. The mechanical analysis indicates that 6% NaOH treatment with a two-hour immersion time gave the highest tensile strength. The adhesion between single fibre and epoxy resin was analysed through the micro-droplet test. It was found that 6% NaOH treatment with a two-hour immersion yielded the highest interfacial shear stress of 3.96 MPa. The TGA analysis implies that alkaline treatment improved the thermal and heat resistivity of the fibre.
  13. Zaty Aktar Mokhtar, Badronnisa Yusuf, Mohammed, Thamer Ahmad, Saiful Bahri Hamzah
    Field surveys of the 2011 Tohoku Tsunami reported massive failures of many seawalls and coastal barriers. The massive damages are vivid evidence that there are flaws in the design of seawalls and barriers. With this as the background, a sequence of laboratory experiments using dam-break waves was performed to simulate the interactions between the tsunami-like bore flow and vertical seawall as well as to measure the bore-induced pressures and to estimate forces exerted on the vertical seawall model. The experimental result revealed that the maximum pressure (approximately 8 kPa) exerted on the vertical seawall was measured at the lowest pressure sensor location. Experimental data were used to re-examine the relevant empirical formulae found in the literature. The obtained results could be useful for calibrating mathematical and numerical models as well as for future research concerning the design of tsunami barriers.
  14. Zaroog, Omar Suliman, Aidy Ali, Sahari, B.B., Rizal Zahari
    Compressive residual stress, induced by mechanical surface treatment, may relax during component
    operation life, due to thermal or mechanical mechanism. Fatigue life prediction for the components which have residual stress will be misled and inaccurately predicted the phenomenon of residual stress relaxation is not considered. Despite putting an effort on incorporating the residual stress relaxation, the issues remain concerned with the technical challenge of measuring and quantifying
    the magnitude of residual stress relaxation as well as redistribution during the loading cycling itself.
    In this paper, the residual stress relaxation and its models were reviewed and discussed to picture
    the best knowledge related to this topic, i.e. whether relaxation is a cause or an effect.
  15. Zalilah Murni Yunus, Norzila Othman, Rafidah Hamdan, Nurun Najwa Ruslan
    A combination of phosphoric acid (H3PO4) 20% v/v impregnation and carbonization method was employed to convert honeydew rind into activated carbons (ACPHDR) for Zn(II) and Cr(III) removal aqueous solution. The characterization of ACPDHR by N2 sorption, iodine number and Boehm analysis result 1272 m2/g surface area, 1174 mg/g and 1.13 mmol/g total acidic functional groups respectively. Fourier transform infrared (FTIR) and Field emission scanning electron microscopy-electron dispersed microscopy (FESEM-EDX) analysis of unloaded and metal-loaded carbon showed shifted of significance peaks and the changes of surface morphology of the sorbent. The adsorption was optimized at pH, shaking duration, initial metal concentration and mass of adsorbent of 5.5, 40 min and 500 mg/L, 0.4 g for Zn(II) and 4, 40 min, 1000 mg/L, 0.1 g for Cr(III) removal. It is concluded that the metal removal was influenced by pH solution, contact time, initial metal concentration and mass of adsorbent. The highest removal of Zn(II) and Cr(III) was observed at 84.24% and 90.10% respectively. Waste from honeydew will be benefited from this research which offer a cheaper alternative precursor to coal based activated carbons.
  16. Zakaria, M.P., Yap, C.K., Eugene Ng, Y.J., Tan, S.G.
    In this study, a polluted site at Kg. Pasir Puteh was assessed for heavy metal pollution by using
    transplanted caged mussel (Perna viridis) from a relatively clean population, Sg. Melayu; both are located in the Strait of Johore. For control purposes, the P. viridis from Kg. Pasir Puteh were also simultaneously transplanted in Sg. Melayu at the same time. It was found that Zn was the metal which got accumulated fastest in the transplanted mussel while Cd was the slowest. This study indicated that the byssus of Perna viridis was most effective for biomonitoring of Cd, Ni, Pb and Zn, while the shell could be used for the biomonitoring of Cu, Ni and Pb and the total soft tissue for the biomonitoring of Ni since they were able to accumulate and eliminate the respective metals well. By using mussel as a biomonitor, the present study found that Kg. Pasir Puteh, which is located in the eastern part of the Strait of Johore, had significantly higher contamination and bioavailabilities of Cd, Cu, Fe, Ni, Pb and Zn. Therefore, the use of the transplanted caged mussels is very useful for heavy metal assessment purposes since it can increase the validity of data interpretation by minimizing ecological factors.
  17. Zainudin, M.F., Hussin, H., Halim, A.K.
    Negative bias temperature instability (NBTI) is the most concern issue CMOS devices with the scaling
    down of the CMOS technologies. NBTI effect contributes to P-MOSFET device degradation which later
    reduce the performance and reliability of CMOS circuits. This paper presents a reliability simulation study
    based on R-D model on CMOS inverter circuit. HSPICE MOSRA model together with the Predictive
    Technology Model (PTM) was used as to incorporate the NBTI model in the circuit reliability simulation
    study for different technology nodes. PTM of High Performance (HP) models of 16nm, 22nm, 32nm
    and 45nm were used in this simulation study. The atomic hydrogen based model was integrated in the
    simulation. The results show that in a CMOS inverter circuit, the threshold voltage shift of p-MOSFET
    under NBTI stressing increased as the year progressed.. The threshold voltage shift was observed to
    increase up to 45.1% after 10 years of operation. The time exponent, n ~ 0.232 of the threshold voltage
    shift observed indicates that the defect mechanism contributed to the degradation is atomic hydrogen.
    The propagation delay increased to 19.5% over a 10-year period. s up to 19.5% from the zero year
    of operation until 10 years of the operation. In addition, the time propagation delay increased as year
    increased when the technology nodes smaller. The finding is important for understanding reliability
    issues related to advanced technology nodes in CMOS circuits study.
  18. Zainap Lamat, Yuhani Jamian, Mohd Agus Adib Eskandar
    Sarawak has experienced several earthquakes of local origin and was also affected by long-distance earthquake that originated from Southern Philippine and the Straits of Macassar, Sulu Sea and Celebes Sea. The objectives for this study were to conduct site specific ground response analysis and develop design response spectra for Bakun area by using 1-D equivalent linear ground response analysis. The site characterisation was carried out utilising the soil profile and soil property data of the selected site. Local surface fault ruptures were investigated for possible hazards due to intraplate earthquakes. Earthquake ground motion records were selected based on characteristics of the controlling earthquakes for an area and the maximum magnitude faults were considered for risk assessment. The site-specific response spectra represent the predicted surface ground motions that reflect the levels of strong motion amplitude and frequency content at a particular site. The site-specific ground response analysis for Bakun site found that the peak ground acceleration at bedrock was amplified from 0.16 g to 0.33 g at the ground surface.
  19. Zainal Abidin Talib, Liew, Josephine Ying Chyi, Zulkarnain Zainal, Mahmood Mat Yunus, W., Lim, Kean Pah, Wan M. Daud, Wan Yusoff, et al.
    This studies are directed towards measuring the electrical conductivity of the (CuSe)1-xSex metal chalcogenide semi-conductor composites, with different stoichiometric compositions of Se (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8,1.0) in bulk form. The electrical conductivity measurement was carried out at room temperature, using the parallel plate technique. The (CuSe)1-xSex composites were prepared using solid state reaction, by varying the ratio of CuSe:Se, in the reaction mixture. The electrical conductivity of (CuSe)1-xSex was determined to be in the range of 1.17 x 10-8 to 1.02 x 10-1 S/cm. The finding indicated that the electrical conductivity value tended to decrease as the concentration of Se increased. The effect of the concentration of Se, on electrical conductivity of (CuSe)1-xSex composites, is discussed in this paper.
  20. Zainal Abidin Kamarul Baharin, Aishah Arinah Abdul Azi
    Ocean offers an inexhaustible source of water which is not consumable by humans due to its high salinity.
    Large amounts of energy are required for desalination, and producing it from fossil fuels can cause harm
    to the environment. As such, solar energy can be used as an alternative energy source to provide cheap
    consumable water. This paper aims to investigate the effects of design parameters on single slope solar
    still evaporation rate under Malaysian conditions. Single sloped solar stills, with varying evaporator basin
    thickness and condenser plate thickness at different separator heights, were fabricated and tested. The 0.5
    mm evaporator basin thickness still set has the highest evaporated volume (250 ml), with evaporation
    percentage of 25%, while the set with a 1 mm evaporator basin thickness has the lowest evaporation
    percentage (5.65%) with 56.5 ml evaporated volume. Experimental results indicate that the single slope
    solar still evaporation rate is very much influenced by climate parameters, namely solar intensity and
    ambient temperature.
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