Score-based structure learning algorithm is commonly used in learning the Bayesian Network. Other than searching strategy, scoring functions play a vital role in these algorithms. Many studies proposed various types of scoring functions with different characteristics. In this study, we compare the performances of five scoring functions: Bayesian Dirichlet equivalent-likelihood (BDe) score (equivalent sample size, ESS of 4 and 10), Akaike Information Criterion (AIC) score, Bayesian Information Criterion (BIC) score and K2 score. Instead of just comparing networks with different scores, we included different learning algorithms to study the relationship between score functions and greedy search learning algorithms. Structural hamming distance is used to measure the difference between networks obtained and the true network. The results are divided into two sections where the first section studies the differences between data with different number of variables and the second section studies the differences between data with different sample sizes. In general, the BIC score performs well and consistently for most data while the BDe score with an equivalent sample size of 4 performs better for data with bigger sample sizes.
One of the issues found in small and medium industry is the poor layout design affecting its productivity
and line efficiency. In automotive industries, more attention should be given in improving assembly line
to increase productivity. This paper presents application of line balancing at the accelerator and brake
pedal assembly line at a small and medium automotive industry. Research methodology employed in
this study includes time study, visualising cycle time based on Yamazumi Chart, distribution of workload
on each workstation using line balancing based on the current takt time and re-layouting the assembly
line. All the proposed layouts are assessed using commercially available software, DELMIA Quest to
evaluate the robustness based on parameters such as fluctuation in demand, availability of the machine,
and operator capacity. Finally, the outputs presented include reduction in manpower, maximum utilisation
of manpower, as well as machine and minimum total production cost. This will lead to productivity
improvement of the assembly line.
Teenage pregnancy is associated with maternal and neonatal morbidity. Some postulate that it is due to biological immaturity, while others postulate that it is due to inadequate antenatal care. The objective of this study is to compare the maternal and neonatal outcome between married and unmarried teenage mothers. A retrospective study was conducted from 2009 to 2012, where mothers aged below 20 year old were included. Maternal and neonatal outcome was assessed. A total of 750 patients aged below 20 year old delivered at Hospital Ampang. The trend of teenage pregnancy decreased from 3.1% in 2009 to 2.2% in 2012. A total of 578 (77.1%) mothers were married, while 172 (22.9%) were unmarried. Being unmarried was significantly associated with unbooked (p<0.001), preterm birth (p= 0.00468), and lower birth weight (p< 0.0001, and unpaired T-Test with 95% CI -0.2607 to -0.0933). However there is no significant difference in the number of mothers with hypertensive disease (p= 0.88428), diabetes in pregnancy (p= 0.39602), mode of delivery (p= 0.055 vaginal delivery, p = 0.4419 caesarean section, and p= 0.9097 instrumental deliveries) and NICU admission (p= 0.3779) between the two groups. Unmarried teenage pregnancy is associated with a lack of antenatal care, preterm birth, and lower birth weight compared to their married counterpart.
Keywords: Marital status, pregnancy outcome, teenage pregnancy
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.
This study aimed to examine the association between second-hand smoke (SHS) exposure and psychological distress amongst non-smoking pregnant women. A cross-sectional study was used to obtain a representative sample of non-smoking pregnant women attending health clinics (n = 661) across six states in Malaysia. The duration of SHS exposure inside and outside the house was recorded from the participants. Psychological distress was assessed via General Health Questionnaire (GHQ12). The analyses were conducted using a logistic regression adjusted for demographic variables and other variables. Amongst non-smoking pregnant women, the prevalence of global SHS exposure and psychological distress was 80.4% and 64.2%, respectively. In the multivariate adjusted odds ratio (OR) models for psychological distress and the duration of SHS exposures, there was an OR of 1.04 (95% CI: 0.61-1.77) for individuals with SHS exposure of 1-4 hours/week, 0.44 (95% CI: 0.23-0.81) for SHS exposure of 5-14 hours/week and 0.84 (95% CI: 0.32-2.22) for exposures of >15 hours/week compared to those with no SHS exposure outside the home. Meanwhile, SHS exposure outside the house with the duration of 5-14 hours might have temporary calming effects against psychological distress. Nonetheless, more research is needed to ascertain this.
Pre-stressing is a concept used in many engineering structures. In this study prestressing in the form of axial compression stress is proposed in the blade structure of H-Darrieus wind turbine. The study draws a structural comparison between reference and prestressed configurations of turbine rotor with respect to their dynamic vibrational response. Rotordynamics calculations provided by ANSYS Mechanical is used to investigate the effects of turbine rotation on the dynamic response of the system. Rotation speed ranging between 0 to 150 rad/s was examined to cover the whole operating range of commercial instances. The modal analysis ends up with first six mode shapes of both rotor configurations. As a result, the displacement of the proposed configurations reduced effectively. Apparent variations in Campbell diagrams of both cases indicate that prestressed configuration has its resonant frequencies far away from turbine operation speeds and thus remarkably higher safety factor against whirling and probable following failures.
Diesel engines produce high emissions of nitrogen oxide, smoke and particulate matter. The challenge is to reduce exhaust emissions but without making changing their mechanical configuration. This paper is an overview of the effect of natural gas on the diesel engine emissions. Literature review suggests that engine load, air-fuel ratio, and engine speed play a key role in reducing the pollutants in the diesel engine emissions with natural gas enrichment. It is found that increasing the percentage of natural gas (CNG) will affect emissions. Nitrogen oxide (NOx) is decreased and increased at part loads and high loads respectively when adding CNG. The reduction in carbon dioxide (CO2), particulate matter (PM) and smoke are observed when adding CNG. However, carbon monoxide (CO) and unburned hydrocarbon (HC) are increased when CNG is added.
This study simulates the nearshore current characteristics at Carey Island by using MIKE 21 Hydrodynamic FM. The model simulations are calibrated and validated against measured conditions by adjusting the values of bed resistant over the stipulated computation domain. To evaluate the accuracy of the simulation results, three statistical parameters, namely RMSE, R Squared, and Thiel’s inequality coefficients are calculated to compare the observed and simulated results. The results indicate that the current speeds during the spring tide are approximately between 0 m/s and 0.64 m/s which come from Northwest to southeast direction. A good agreement between observed and simulated values of current speeds, current direction and water level with R squared of approximately 0.92 to 0.95 are obtained. Results suggest that the bed resistant is an important parameter in the hydrodynamic simulation using MIKE 21 Hydrodynamic FM.
io-electricity generation by Microbial Fuel Cell (MFC) has gained considerable attention due to
its integration with wastewater treatment such as Palm Oil Mill Effluent (POME). Investigation
into pH effect and determination of optimal pH value ranges growth for acidogenic, acetogenic
and methanogenic by natural mixed culture
electroactive bacteria (exoelectrogens) growth
in original non-Deoxygenated Mixed POME
(nDMP) and Deoxygenated Mixed POME (DMP)
in MFC was carried out. Current generation,
power generation and maximum power were
also monitored. Experimental results show that
exoelectrogens in nDMP with pH 6.8 yielded the
highest current generation of 61.51 mAm-2 and
maximum power of 17.63 mWm-2. Overall, nDMP
substrates with 3 pH ranges (5.5, 6.8 and 8.0)
showed equal potential to generate power that is
higher than DMP substrates. Comparison carried
out for inter DMP substrates demonstrated that
DMP with pH 6.8 and DMP with pH 8.0 showed equal potential to generate power, but not for DMP with pH 5.5. Subsequently, nDMP with pH 6.8 and
nDMP with pH 8.0 showed equal potential for higher maximum power compared to nDMP with pH
5.5 and DMP substrates. This finding indicates that mixed microbial communities in DMP substrate
are dominant with obligate anaerobic exoelectrogens bacteria which have less capability to generate
electricity compared to nDMP substrate that was dominated by the aerotolerant and/or facultative
anaerobic exoelectrogens bacteria.
Numerous studies of polylactide nanocomposites have been conducted. However, the role and importance
of processing conditions is the subject of very few papers. In this work, polylactide and a constant
amount (2 %w/w) of organoclay Cloisite® 30B via melt intercalation technique were produced. It is
generally believed that maximum benefits are achieved when organoclay is well dispersed in PLA
matrix. It might be anticipated that melt processing conditions would have an important influence on
the nanocomposites formed. Experimental design was carried out based on Box-Behnken methods, a
response surface methodology (RSM) well suited to the goal of process optimisation. Three levels of
processing temperature, rotor speed and mixing time were chosen in this study. The response was Young’s
modulus. The interaction effects with the most influence on the Young’s modulus of these PLA/organoclay
nanocomposites are temperature and speed. The maximum Young’s modulus was predicted to be 1211
MPa at a temperature, speed, and time of 175°C, 100 rpm, and 7 min, respectively. Understanding the
influence of processing conditions on the mechanical properties is needed for improving nanocomposites
properties. Mathematical model and optimisations plot were used to illustrate the relationship between
the parameters and mechanical properties considered. Results of the data analysis using Minitab software
are presented.
In this work, the removal of Methyl Orange (MO) from aqueous solution was studied using a new nonconventional
and eco-friendly adsorbent, spent tea leaves (STL). Untreated and acid treated STL were
used as bio-adsorbent for removal of MO using batch method. Effects of different STL dosages (1 – 4
g), pH solutions (2–11) and initial dye concentrations (10 – 60 mg/L) were investigated. Adsorption
experiments conducted using acid treated STL resulted in higher MO removal efficiency ranging from
79 to 92% for 1-4 g of adsorbent dosage compared to the untreated ones which resulted in only 18 to
56% of removal for the similar amount of dosage. In addition, acidic condition favours the MO removal
as compared to alkaline medium. Experimental data were analysed using the Langmuir and Freundlich
models of adsorption and it was found that adsorption isotherm was best described by Freundlich model
and pseudo-first order equation with high correlation coefficient. Results revealed that acid treated STL,
being a waste, has the greater potential to be used as adsorbent for MO removal from aqueous solution.
This paper reports a study of the formation of cellulose nanofibres from kenaf waste using chemical
extraction method. The extracted holocellulose was then prepared for acid hydrolysis to form the
cellulose. Before mixing it with polyvinyl chloride (PVA) solution and extruded using electrospinning
under different parameters to produce PVA/kenaf nanofibres. Results showed that the morphological
structures of PVA/kenaf nanofibres varied at different voltages. An increase in voltage from 10 kV to 20
kV produced more beads along the fibre length. In addition, the applied voltages were found to affect the
resultant fibre diameter of the PVA/kenaf nanofibres. The results also showed that the electrospinning
parameters affect the shapes of the PVA/kenaf nanofibre membranes. Based on the experimental works,
the optimal applied voltage was found to be at 15 kV, where the resultant fibre diameter and membrane
coverage area were approximately 43.9 ± 3.1 nm and 214.2 ± 15.8 cm2
, respectively.
This paper investigates the flexural properties of Arenga Pinnata fibre reinforced epoxy composite
(APREC) in relation to its fibre arrangement. The composites were produced using Arenga Pinnata fibre
as the reinforcement material and epoxy resin as the matrix. In this work, two types of Arenga Pinnata
fibre arrangement were under-studied, randomly distributed and unidirectional distributed (UD). Samples
were prepared at 10vol%, 15vol%, 20vol%, and 25vol% of fibres reinforcement to matrix ratio for both
types. Three-point bending configuration flexural tests were performed for both randomly distributed
APREC and UD APREC at 10vol%, 15vol%, 20vol%, and 25vol% respectively. Results indicated that
UD APREC have better flexure modulus and flexure strength for all the fibre loading percentages (vol%)
as compared against the randomly distributed APREC. The 25vol% UD APREC showed the highest
modulus (3.783 GPa) with an increment of 31.0% as compared against the pure epoxy (2.888 GPa).
It was also observed that there was no significant increment on flexure strength for both random and
unidirectional APREC as compared to pure epoxy (61.125 MPa), but the flexure strength value decreased
for randomly distributed fibre orientation for all fibre volume percentages (vol%)
The incident of beach pollution in Batu Ferringhi in year 2014 has created a major concern over water
quality at the tourists’ haven. In order to understand advection and dispersion of pollutants in the area,
a coastal hydrodynamic model of Batu Ferringhi beach was developed in this study by taking into
consideration its wind, tide, coastal current and riverine runoff. The model was calibrated and validated
through observations from adjacent coastal monitoring stations. Simulation was then carried out to
investigate scenario of the constituent water quality which originates from the three rivers in the vicinity.
Results showed high concentrations of water quality parameters observed near the headland towards the
northeast of the study area, with intermittent patchy escape which may retain more than one-third the
initial concentrations, weighted by the river discharge. Even more worrying is that localised trapping of
up to three-quarter the initial weighted concentrations also occurs at the beach, owing to the interactions
between river flow and longshore current.
Chemical industries are greatly assisted by catalysts; and commonly used catalysts for C-C formation
reactions are mainly phosphine-based complexes which are air and moisture sensitive. New air stable
Schiff base Pd(II) complexes have been synthesised, characterised and screened for their catalytic potential.
This paper reports three ONNO Schiff bases, namely, L2C [2,2’-((1E,1’E)-((2,2-dimethylpropane-1,3-
diyl) bis (azanylylidene)) bis (methanylylidene)-) bis (4-chlorophenol)], L2M [2,2’-((1E,1’E)-((2,2-
dimethylpropane-1,3-diyl)bis(azanylyli-dene)) bis (methanylylidene)) bis (4-methylphenol)] and L2H
[2,2’-((1E,1’E) - ((2,2-dimethyl-propane-1,3-diyl) bis (azanylylidene)) bis (methanylylidene)) diphenol].
These were synthesised from 2,2-dimethyl-1,3-propanediamine and salicylaldehyde derivatives with Cl,
CH3 and H at the meta position, respectively. The compounds were reacted with palladium(II) acetate
yielding three palladium(II) complexes denoted as PdL2C, PdL2M and PdL2H. The structures of all
compounds were elucidated through elemental analysis, 1
H and 13C NMR, FTIR and melting point. The
complexes were screened for catalytic activities in Sonogashira coupling reaction between iodobenzene
and phenylacetylene in DMSO. PdL2H was found to be the most active catalyst with 87% iodobenzene
conversion after 12 hours of reaction.
A new series of N,O-bidentate ligands, L1, L2, L3 and L4, and their Pd(II) complexes, PdL1, PdL2, PdL3
and PdL4 have been synthesised and characterised using various physico-chemical techniques, namely
elemental analyses, IR and 1
H and 13C NMR spectroscopies, and conductivity analysis. The molecular
geometries of PdL2 and PdL4 have been elucidated through single crystal X-ray crystallography revealing
2:1 molar equivalence of ligand: Pd with the Schiff bases that exhibited bidentate ligands behaviour,
in which they coordinated through the phenolic O donor atoms and imine N. Upon complexation, the
ν(C=N) around 1629-1639 cm-1 and ν(C-O) around 1251 to 1252 cm-1 shifted to lower frequencies by 4
to 23 cm-1. In this study, three parameters were chosen for the reaction conditions optimisation, which
were types of bases, loadings for the catalyst, and temperatures of the reaction. Pd(II) complexes exhibited
good catalytic activities for Heck coupling reaction with 100% conversion at 100°C within 12 hours of
reaction time. Reducing the reaction temperature to 80°C reduced the conversion to a maximum of 80%.
In IEEE 802.11 standard, Mobile Station (MS) such as laptop and smartphone are connected to Access
Point (AP) to have a wireless connection. However, setting up AP to cover the whole area is costly and
complicated. Limitation in signal capacity causes out-of-coverage area, where the MS cannot connect to
the AP. In this paper, a portable wireless range extender (PWRE) is developed to assist MS that is located
out of coverage area, or at the cell edge area connected to the internet. Development of PWRE involves
two processes, which are connecting to existing wireless LAN (WLAN) network, and broadcasting a new
WLAN network. The paper discusses development process of PWRE and analysis of its performance.
PWRE was developed using a low power consumption microprocessor, known as Raspberry Pi.
Performance of the developed PWRE is evaluated by comparing signal strength received by an MS
located in the cell edge from an AP using two scenarios; with and without the PWRE. Results showed
that the MS signal strength improved significantly with the deployment of PWRE. Other advantages
offered by PWRE include being portable and energy efficient as it uses only 5V of power to operate.
After ABO, Rhesus (Rh) is the second most clinically important blood group regarding transfusion
and pregnancy induced alloimmunisation. RhD DEL is a subtype of variant RhD, which is difficult to
determine in a routine blood bank, since it expresses an extremely low level of D antigens. Serologically,
it can only be detected via adsorption-elution test. To date, there have been limited data available on the
Rhd DEL phenotype in Malaysia. Thus, this study was carried out to detect DEL phenotype among RhD
negative donors in Malaysia. A total of 43 RhD-negative blood samples were collected from National
Blood Centre, Malaysia. Rh phenotype for each sample was tested, followed by adsorption elution
technique. Then, identification of DEL carrying RHD1227A allele was performed via SSP-PCR. Rhphenotype
identified were ccee (79.07%), Ccee (13.95%), 4.65% of ccEe phenotype and only 2.33% of
CCee phenotype. One (2.3%) out of the 43 samples was identified as DEL phenotype carrying RHD1227A
allele when tested using SSP-PCR, but none was identified from adsorption-elution. A larger sample
size is recommended to determine the exact prevalence of DEL phenotype, as well as specificity and
sensitivity between SSP-PCR as compared with the traditional adsorption elution technique.
Temporal distribution of forecasted wind speed is important to assess wind capacity for wind-related
technology purposes. Regional wind energy estimation needs the development of wind pattern to monitor
and forecast temporal wind behaviour. Temporal wind in Malaysia mainly depends on monsoonal factor
that circulates yearly and each monsoon derives distinct character of wind. This paper aims to develop a
model of wind speed pattern from historical wind speed data. Then, the model was used to forecast 5-years
seasonal wind speed and identify temporal distribution. Wind speed model development and forecast
was performed by identifying the best combination of wind speed seasonal component using Seasonal
Auto-regressive and Moving Average (SARIMA) model. Thus, three distribution models, Lognormal,
Weibull and Gamma models, were exploited to further observe consistency using Kolmogorov-Smirnov
goodness-of-fit test. The best fit model to represent seasonal wind distribution in each monsoon season
at Pulau Langkawi, Malaysia, is Log-normal distribution (0.04679-0.108).
Aspergillus sp. is an extremely resilient species that can be found everywhere in the environment and
is present abundantly in water and soil. The defining characteristic of Aspergillus sp. is their extensive
hyphal network which enable them to survive anywhere, even in very harsh conditions. This study was
carried out to isolate the filamentous fungi from peat soil of animal agricultural farm and characterise
them based on their morphological and molecular characteristics. Growth rate of each isolated fungi was
also evaluated in order to determine the period of maturity for each fungi. Soil samples were collected,
weighed and then dissolved in sterile distilled water. The samples were serially diluted and spread
onto potato dextrose agar (PDA) for isolation. Different isolated colonies that were morphologically
different from each plate was purified and sub-cultured onto new media for macroscopic and microscopic
identifications. For molecular identification, a conventional technique was used in genomic DNA
extraction of filamentous fungi due to their thick cell wall and presence of surface proteins protecting the
fungus. These characteristics make it difficult to harvest the genomic DNA. Polymerase chain reaction
(PCR) was carried out using internal transcribed spacer primers; ITS1 (forward) and ITS4 (reverse).
The morphological identification and molecular
technique showed that majority of these isolated
fungi are Aspergillus sp.