One of the concerns in power system preventive control and security assessment is to find the point where the voltage and frequency collapse and when the system forces a severe disturbance. Identifying the weakest bus in a power system is an essential aspect of planning, optimising and post-event analysing procedures. This paper proposes an approach to identify the weakest bus from the frequency security viewpoint. The transient frequency deviation index for the individual buses is used as the weakest bus identification as well as a frequency security indicator. This approach will help to determine the bus with the worst deviation, which helps to analyse the system disturbance, takes proper control action to prevent frequency failure, and most importantly, observes consumer frequency. The approach is applied to the WSCC 9 bus test system to show the feasibility of the method.
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.
The present conventional (destructive) method used in determining LAI is laborious, difficult and time consuming. Thus, an image-based measurement using camera system with fish eye lens offers an alternative means for an accurate indirect measurement of LAI in oil palm. In this study, a methodology was developed to improve the leaf area index of the oil palm determination using hemispherical photography as an indirect method. A set of true LAI data, collected using the destructive method, were used as a reference to calibrate the LAI measurements obtained by the hemispherical photography. A good relationship (r = 0.85) was found between age of palm and hemispherical photographic LAI. However, the estimated LAI obtained by the hemispherical photographic method was underestimated as compared to the destructive method. Some means of calibration was necessary to determine the relationship between the actual LAI and the hemispherical photographic LAI. It was necessary to multiply the LAI value from 5 years to 16 years, by a clumping factor of 2.14 for 5 to 9 year old palms, 2.33 for 10 to 14-year old palms and 2.37 for above 15- year old palms to calculate the accurate LAI values. For palms which are less than 5 year old (i.e. 2 to 3 years in this study), the photography LAI value was equal to the calculated LAI value. This proposed that correction factors would solve this underestimation effect. In addition, two equations were also proposed to estimate the true LAI from the Photographic LAI for immature and mature oil palm plantation.
Failure of pancreas can cause uncontrolled blood glucose levels in the body. This research focuses on type 1 diabetes patients who depend on external insulin injection. The Hovorka model was used as the mathematical model in the development of control algorithm for artificial pancreas. However, the model showed a lack of interaction on selected parameters and variables in its glucose-insulin dynamic system. An improvement on the Hovorka equations was done, but no work was carried out to simulate the proposed equations. The objectives of this study are to simulate the modified Hovorka equations using MATLAB and to compare the simulation results between the reference and modified ones. This study showed better interaction among all variables and parameters on its glucose-insulin dynamic system using the modified equations compared to the original equations. The lower administered amount of insulin, Ut at 16.7mU/min and 20mU/min could regulate the blood glucose level at normoglycemic condition throughout the study.
Mobile users have the capability of accessing information anywhere at any time with the introduction of mobile browsers and mobile web search. However, the current mobile browsers are implemented without considering the characteristics of mobile searches. As a result, mobile users need to devote time and effort in order to retrieve relevant information from the web in mobile devices. On the other hand, mobile users often request information related to their surroundings, which is also known as context. This recognizes the importance of including context in information retrieval. Besides, the availability of the embedded sensors in mobile devices has supported the recognition of context. In this study, the context acquisition and utilization for mobile information retrieval are proposed. The “just-in-time” approach is exploited in which the information that is relevant to a user is retrieved without the user requesting it. This will reduce the mobile user’s effort, time and interaction when retrieving information in mobile devices. In this paper, the context dimensions and context model are presented. Simple experiments are shown where user context is predicted using the context model.
Tailing sand is the residue mineral from tin extraction that contains between 94% and 99.5% silica, which can be used as moulding sand. It is found in abundance in the Kinta Valley in the state of Perak, Malaysia. Adequate water content and clay in moulding sand are important factors for better strength and
casting quality of products made from tailing sand. Samples of tailing sand were investigated according
to the American Foundrymen Society (AFS) standard. Cylindrical test pieces of Ø50 mm×50 mm in height from various sand-water ratios were compacted by applying three ramming blows of 6666g each using a Ridsdale-Dietert metric standard rammer. The specimens were tested for green compression strength using a Ridsdale-Dietert universal sand strength machine. Before the tests were conducted, moisture content of the tailing sand was measured using a moisture analyser. A mixture bonded with 8% clay possesses higher green compression strength compared to samples bonded with 4% clay. The results also show that in order to achieve maximum green compression strength, the optimum allowable moisture content for mixtures bonded with 8% clay is ranged between 3.75 and 6.5% and for mixtures bonded with 4% clay is 3-5.5%.
Research on the use of Jatropha curcas triglycerides as biodiesel feedstock has received worldwide attention due to its inherent characteristics. Unlike palm oil, J. curcas oil is not edible, and thus, it will not disturb the food supply. However, to the researchers' experiences with the synthesis of J. curcas, oil-based biodiesel has shown that the fuel characteristics depend largely on the type of alcohol used as the excess reactants. Transesterification reaction is chosen for this process with sodium methoxide as the catalyst. Comparison studies on the yield of esters using methanol and ethanol, as well as the impacts on the reaction rate are discussed. The effects of reaction time and molar ratio on the reaction conversion are also examined. The determination of reaction yield is based on the conversion of triglycerides into alkyl esters as the main product. The findings are described as follows: the highest percentage yield of product is attained at 96% for methanol as an excess reactant, and this is 90% when ethanol is used. The optimum conditions of parameters are achieved at 6:1 molar ratio of alcohol to triglycerides, 50 min of reaction time and reaction temperature of 65°C for methanol and 75°C for ethanol. The biodiesel properties of both ester fuels were determined according to the existing standards for biodiesel and compared to the characteristics of diesel fuel.
Malaysian Studies is a compulsory course for international undergraduate students in Malaysia. The
subject comprises Malaysian history, its governance and administration system. Due to different sociocultural
backgrounds and histories, most, if not all, international students, struggled with this subject.
This research project aims to create, implement and evaluate a mobile application (app) as a catalyst for
mobile learning (m-learning) for one particular topic of the Malaysian Studies course. The increased
use of technology in learning environments has changed instructional approaches by making it more
accessible and essentially, more student-centered. Using a design-based research approach, the mobile
app is aimed to guide students to write their own notes to assist in deeper understanding of the subject.
The mobile app was also reviewed by users to gauge its effectiveness and ease of use. Findings from the
tests showed the potential to structure the students’ learning from the topic. From the research, there are
a few improvements and suggestions that could be implemented for similar future studies and projects.
This paper highlights basic data collected over the 7 years and 8 years of establishment of the marine turtle hatchery projects in Pulau Rusukan Besar Marine Park Centre (PRBMPC), Federal Territory of Labuan and Pulau Redang Marine Park Centre (PRMPC), Terengganu; Malaysia, respectively. Compiled data were taken from year 2010 until 2017. The within and between season patterns in terms of nest number of the green (Chelonia mydas) and hawksbill (Eretmochelys imbricate) turtles were shown. The population of marine turtles were estimated from the number of nests laid. Total annual nests were used as a crude index of female turtle abundance. Green turtles accounted for 96.18% (1,233 nests laid) of the total nesting recorded while hawksbills accounted for the remaining 3.82% (49 nests laid) in the PRMPC. However, in the PRBMPC 23.58 % (29 nests laid) and 76.42% (94 nests laid) were recorded respectively for the green and hawksbill turtle. 100 % of the nest laid have been incubated using the ex-situ conservation method with the production of 103,929 and 23,558 live green and hawksbill turtle hatchlings respectively. The 8-year average hatching and emergence success rates for green turtles and hawksbills were 87.11 and 88.33%, and 91.56 and 90.69% respectively. This paper provides important information that is fundamental for the understanding of population status to ensure effective conservation measures and management of marine turtles at both marine parks.
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.
This study sought to examine the reliability and validity of height measurements using a portable
stadiometer as compared to a mechanical scale. Samples from 142 adults aged 22 to 57 were taken during data collection in November 2014. There was a high degree of reliability for the inter-examiner, intraexaminer and inter-instrument aspects with regards to mean difference, the inter correlation coefficient (ICC) and Bland-Altman Plot. For the inter-examiner aspect, the height measurement taken by the first examiner was 0.01 cm higher than that by the second examiner with an ICC of 0.999. For the intraexaminer aspect, the difference was 0.1 cm; this was higher in the first measurement compared to the second. The ICC was also 0.999. For the inter-instrument aspect, measurement taken by stadiometer was 0.61 cm higher than the measurement taken by mechanical scale and the ICC was 0.997. The Bland-Altman plot showed a distribution of differences between measurements in the inter-examiner, intraexaminer and inter-instrument aspects that were close to zero within the narrow range of ±1.96SD. The technical error of measurement (TEM), coefficient of reliability (R) and coefficient of variation (CV) for the inter-examiner, intra-examiner and inter-instrument aspects were within the acceptable limits. This study suggests that the portable stadiometer is reliable and valid for use in community surveys.
Tocotrienols have been reported to possess potent cholesterol lowering, anti-hypertensive, antiinflammatory and anti-oxidative properties which are superior to tocopherols. Emerging evidence suggests pure tocotrienols have anti-atherogenic properties. However, optimal doses of oftocotrienolrich fraction (TRF) in progressive atherogenesis remain unclear. This animal model experiment was designed to investigate the effects of a range concentration of TRF supplementation on the extent of atherosclerosis and soluble lipids, inflammatory and oxidative stress biomarkers in high-cholesterol diet (HCD) induced hypercholesterolaemic (HC) rabbits with atherosclerosis. A total of 28 New Zealand white rabbits were given 1% high-cholesterol diet (HCD) for two months and then randomised into five groups: Placebo (n=7), TRF 15 mg/kg (n=5), TRF 30 mg/kg (n=6), TRF 60 mg/kg (n=5) and TRF 90 mg/kg (n=5) daily. The treatment was given for three months and the animals were fed HCD throughout the duration. Aortic vessels were obtained to assess the extent of atherosclerotic lesions at the end of the study. Fasting serum lipids (FSL), C-reactive protein (CRP), malondialdehyde (MDA) and 8-isoprostane levels were measured at baseline, one and two months post-HCD, one, two, and three months postintervention. There were no differences in the extent of the atherosclerotic lesions, percentage changes of FSL, MDA, 8-isoprostane and CRP levels between the placebo and TRF groups. In conclusion, TRF across all doses studied have neutral effects on atherosclerotic lesions, soluble lipids, biomarkers of oxidative stress, coronary risk and inflammation in severely atherosclerotic rabbits with progressive and continuous insult by high cholesterol feeding.
The formation of intermetallic compound (IMC) layer at the interfaces of pad finishes has been studied.
The growth of IMC layer as a reflow process and its properties were also discussed. In this study, solder
alloy SAC237 (Sn: 99 wt.%, Ag: 0.3 wt.%, Cu: 0.7 wt.%), reinforced with 0.01 wt.% Multi-Walled
Carbon Nanotubes (MWCNTs), was mixed to form a composite solder paste and soldered on Electroless
Nickel Immersion Gold (ENIG) and Immersion Tin (ImSn) pad finishes. Reflow process was conducted
in oven with specific reflow profile. The growth and properties of IMC layer were analysed using optical
microscope with image analyser. Results showed that the thickness of IMC layer for ENIG and ImSn
were 1.49 and 2.51 µm, respectively. Floating IMC and voids within the solder bulk and IMC layer
were also identified in the samples. In addition, the measured wetting angle for ENIG and ImSn were
16.21° and 34.32°, respectively.
Normalisation is a process of removing systematic variation that affects measured gene expression levels
in microarray experiment. The purpose is to get a more accurate DNA microarray result by deleting
the systematic errors that may have occurred when making the DNA microarray slid. In this paper,
four normalisation methods of Global, Lowess, Quantile and Print-tip are discussed, tested and their
final results compared in the form of Matrixes and graphs. Ideal and real microarray slides have been
used for this project. It was found that the Print-tip normalisation method showed the closest results to
the real result for an ideal microarray slide and it has a straight median line final graph. The Print-tip
normalisation method uses more than one normalization factor that is divided among intervals which
are dependent on the values of the addition of red and green logarithm.
A number of different studies were reviewed to investigate the functionality of splitter plates for the
purpose of drag reduction and vortex elimination behind a circular cylinder. The studies were carried
out numerically or experimentally in different combinations of Reynolds range, 2D or 3D dimensions,
with intention of drag reduction, vortex suppression or both. Results were compared to discover the
generalities of a splitter plate’s applications and its performance in drag reduction and vortex control.
The reduction of 12% up to 38.6% in drag coefficient suggests that all reviewed studies verified the
effectiveness of upstream plate in drag reduction. Varied upstream plate’s gap ratios (gap between the
plate and cylinder) were tested and the optimum position was obtained. For the finite cylinder case,
however, the studies discovered that the effectiveness of upstream plate decreased severely and thus, are
barely considered as a drag reductive tool for shorter cylinders. Although downstream plate influences
drag force, its prominent application is found to be vortex shedding elimination (up to 14.7%). The
length ratio and gap ratio of downstream plate were varied in these studies and it was found that the
length ratio was a more important factor compared with the gap ratio in the case of vortex suppression.
Thermal characterization of sugar palm fibre (SPF), reinforced high impact polystyrene (HIPS)
composites, was studied by means of thermogravimetric analysis. The effects of alkaline treatment and compatibilizing agent on the thermal stability of the composites were evaluated. Alkaline treatment was carried out by soaking the fibres in 4 and 6% of NaOH solution, while treatment with compatibilizing agent was employed by adding 2 and 3% maleic anhydride-graft-polystyrene (MA-g-PS) to the composites. Both the treatments were aimed to improve the mechanical performance of the composites. From the study, the thermal stability of the treated composites was found to be higher than that of untreated composites. It is shown that the incorporation of sugar palm fibre influences the degree of thermal stability of the composites. The treatments on composites also contributed to shifting the peak temperature of degradation of the composites. In other words, there are strong chemical reactions between the components of the treated composites. The thermal stability of the composites, with alkaline treatment and compatibilizing agent, was found to be better as compared to those of the untreated composites.
This study deals with the analysis of the cure rate estimation based on the Bounded Cumulative Hazard (BCH) model using interval censored data, given that the exact distribution of the data set is unknown. Thus, the non-parametric estimation methods are employed by means of the EM algorithm. The Turnbull and Kaplan Meier estimators were proposed to estimate the survival function, even though the Kaplan Meier estimator faces some restrictions in term of interval survival data. A comparison of the cure rate estimation based on the two estimators was done through a simulation study.
Kenaf natural fibre is used as a sustainable form of material to reinforce polymeric composite. However, natural fibres usually do not perform as well as synthetic fibres. Silica nanoparticle is a material with high surface area and its high interfacial interaction with the matrix results in its improvement. In this research, silica nanoparticles were introduced into epoxy resin as a filler material to improve the mechanical properties of the kenaf-reinforced epoxy. They were dispersed into the epoxy using a homogeniser at 3000 rpm for 10 minutes. The composites were fabricated by spreading the silica filled epoxy evenly onto the kenaf mat before hot pressing the resin wet kenaf mat. The results show for flexural properties, composites with higher fibre and silica volume content generally had better properties with specimen 601 (60 vol% kenaf and1 vol% silica) having the highest strength at 68.9 MPa. Compressive properties were erratic with specimen 201 (20 vol% kenaf and 1 vol% silica) having the highest strength at 53.6 MPa.
An in-house quasi-dimensional code has been developed which simulate the overlap, intake, compression, combustion, as well as expansion and exhaust processes of a homogeneous charged internal combustion engine (ICE). A detailed chemical kinetic mechanism, constituting of 39 species and 148 elementary reactions, has been used in conjunction with above code to study the combustion of CNG under IC engine conditions. Two different criteria, based on pressure rise and mass of fuel burned, are used to detect the onset of ignition. Parametric studies are conducted to show the effect of compression ratio, initial pressure, intake temperature and equivalence ratio, on the time of ignition and fuel burning rate. The results obtained from the modelling show a good agreement with the experimental data.
Surface sediment samples were collected from five locations at the downstream of Klang River in January 2007 to examine the spatial distribution, composition, and sources of 19 parent polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbon (n-alkanes) using gas chromatographymass spectrometry. The total concentrations of the 19 PAHs in the sediments were found to range from 1304 to 2187 ng g-1 sediment. Meanwhile, total concentrations of n-alkanes ranged from 17008 to 27116 μg g-1 sediment. The concentration of n-alkanes in the sediment was significantly correlated (r = 0.991, p = 0.001) with the content of sediment organic carbon. In this study, all the sediments exhibited phenanthrene/anthracene (PHE/ANT >15) fluoranthene/(fluorantene+pyrene) (FLT/FLT+PYR < 0.4), ethylphenanthrenes/phenanthrene (MP/P >1), combustion PAHs/total PAHs (CombPAH/Σ19PAH