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Modelling of extreme temperature and its correlation with ENSO : a case study in Perlis
No full textMaster of Science in Engineering MathematicsExtreme value (EV) theory has raised researcher's attention for modelling and forecasting the catastrophic or high-risk events. Since extreme environmental events may cause huge loss of properties and affect human life, therefore it is significant to
understand the behavior of such uncommon events and predict the upcoming. EV theory affords some understanding to the tail of a distribution where standard models have proved unreliable. The generalized extreme value (GEV) distribution is used to model
the extreme based on block maxima method. Inference of the extremes of environmental events is essential as a guideline in designing structures to survive under the utmost extreme condition. Extreme temperature caused various effect and can be
associated with human health and material damage. Meanwhile, El Nino Southern
Oscillation (ENSO), is a climate condition that happened all year round globally. The
EV theory is applied through GEV with two approaches, Maximum Likelihood
Estimate (MLE) and L-Moments (LM) to model the extreme temperature in Chuping,
Perlis and hence estimates the future extreme levels. The issue of block size is
discussed. The goodness of fit (GOF) test is done using root mean squared error
(RMSE) and Kolmogorov Smirnov (KS) test to determine the best approach. From the
results, it is found that MLE is better than LM for the yearly block but LM squared
things up for the monthly block. The return level is expected to exceed the maximum
value 40.1oC at certain return periods. The moderate correlation coefficient, r is
obtained in finding the relation between extreme temperature and ENSO. So, it is
proofed that ENSO events influences extreme temperature in Chuping, Perlis
Numerical simulations of innovative ground plane and double-gate configurations in thin-body and -buried oxide of SOI MOSFETS
No full textDoctor of Philosophy in Microelectronic EngineeringThe downscaling of transistors enables an increased in transistor density, faster switching speeds and greater complexity with no increase in power consumption. However, the scaling of the conventional planar MOS transistors appears to be reaching
the end of the technology roadmap due to worsening performance variability and shortchannel
effects (SCEs). One of the contenders anticipated to replace the current transistor architecture is planar ultra-thin body and BOX (UTBB) SOI MOSFET. The advantage of the thin-body SOI structure lies in its simple planar process which is fully
compatible with the bulk silicon CMOS flow. In this research work, a particular
attention is being given to the performance of UTBB SOI MOSFETs with its thin BOX
in improving electrostatics behaviour namely of drain-induced barrier lowering (DIBL)
of the thin-body as compared to thick BOX (UTB) SOI transistors for extending CMOS
scalability. Subsequently, UTBB with different ground plane (GP) architectures and
gate configurations (i.e. single-gate (SG) vs double-gate (DG)) are extensively studied
through numerical simulations as possible candidates for the continuation of Moore‟s
Law. In-depth study of the digital and analog/RF figure-of-merit (FoM) are carried out
in a wide range of frequency (from 0.01 Hz to 100 GHz) in correlation with device
operation mechanisms. It is discovered that an innovative GP formation made of
localized GP of p-type in the substrate underneath the channel (referred herein
throughout the thesis as GP-B) effectively suppress substrate depletion effects and
shows better immunity against SCEs from the digital analysis viewpoint. Further
improvements in the immunity against SCEs can be achieved in DG configurations
where the impact of different GP architectures is amplified as compared to SG. Even
though the use of DG configurations provides superior digital performance, lower
current gain cut-off frequency (ft) values are produced than SG in the analog domain
due to an increase of gate-to-gate capacitances (Cgg). Therefore, careful selections and
trade-offs are needed when selecting a particular device structure where the results
obtained in this research work contribute to the identifications of GP architectures and
gate configurations (SG or DG) that can be adopted in device design to suit specific
applications of either digital or RF
Effects of water and nitrogen stresses on growth, phytochemicals and antioxidant of orthosiphon stamineus plant
No full textDoctor of Philosophy in Bioprocess EngineeringAbiotic stresses particularly water stress and nutrient deficiency may elicit the biosynthesis pathway of herbal metabolites, where they are also useful to enhance the yield of herbal metabolites. Thus, this study was carried out to investigate the effects
of soil water and nitrogen stresses on the accumulation of herbal bioactive compounds. The primary experiment was to refine the methanol extraction conditions (methanol concentrations and times) in order to improve extract quality of O. stamineus. The leaf
and stem were extracted in 0, 25, 50 and 100% methanol for 2, 4 and 8 hours at 400C. The results of total phenolic content and antioxidant capacity were increased when the leaf and stem extracted with 50% methanol but the time extraction did not influence
the phenolics concentration and the antioxidant capacity. For the bioactive compunds concentration, the rosmarinic acid is the highest bioactive compounds as compared to 3’-hydroxy-5,6,7,4’-tetramethoxyflavone, sinensetin and eupatorin when extracted
with 100% methanol for 4 hours. Another experiment was to investigate the effects of water stress at different levels and duration on bioactive concentration of O. stamineus
leaf, stem and root. The water stress were set; high (25-35% of field capacity),
moderate (45-65% of field capacity) and low (75-90% of field capacity). The water
stress levels and stress duration main effects have significantly influenced the
phenolics and flavonoids content in the leaf, stem and root of O. stamineus plant. For
the bioactive concentration, the leaf, stem and root was significantly increased when
treated for 4 week of water stress. The enzyme activity reveals that the cinnamic acid
4-hydroxylase activity increased when the plant stressed for four weeks. Next
experiment aimed to identify the effects of nitrogen stress at different levels on
bioactive concentration of O. stamineus leaf, stem and root. They were consisted of 0
N kg/ha (high N stress), 110 N kg/ha (low N stress), 170 N kg/ha (medium N stress)
and 250 N kg/ha (control). The phenolics and flavonoids content for the plant was
significantly affected when the plant imposed with medium N stress but the N stress
had not influenced the antioxidant capacity of the plant. The N stress also not
significantly affects the bioactive concentration in leaf, stem and root of O. stamineus
plant. The last experiment was to determine the effects of water and nitrogen stresses
at different levels on bioactive concentration of O. stamineus plant
The effect of integration practices of total quality management and supply chain management on operational performance: The roles of technological capabilities and lean manufacturing practices
No full textDoctor of Philosophy in ManagementThe main objectives of this study are to examine the integration of total quality management and supply chain management practices as a new approach, and to examine the mediating role of lean manufacturing practices and the moderating role of technological capabilities in the effects of leadership and strategic planning (LSP), employees involvement and commitment (EIC), information technology system (ITS), supplier relationship (SR), continues improvement and innovation (CII), customer focus (CF) as a viable practices after integration on operational performance (OP) of manufacturing
industries in Jordan (JMIs). Data were collected from the JMIs that listed in Amman stock
exchange which practicing total quality management, supply chain management systems
and lean manufacturing practices using a cross-sectional study design. This study chose 55
firms randomly, and questionnaires were distributed and collected through the personallyadministered
method. Partial Least Squares Structural Equation Modelling (PLS-SEM) was
used to test the study hypotheses. This study finds that LSP, EIC, SR, CII, ITS and CF are
important integration practices of total quality management and supply chain management
for the OP of JMIs. The findings reveal that lean manufacturing practices of JMIs depends
on the degree of LSP, EIC, ITS, SR, and CF of the firm. It is expected CII would improve a
firm‘s practicability to lean manufacturing, but the finding of this study does not support
this expectation CII negatively influences OP. Interestingly, the results further show that
with better lean manufacturing practices, LSP, EIC, ITS, SR, CII and CF influence OP.
Furthermore, technological capabilities does not have a significant moderating influence on
the paths between LSP and OP, EIC and OP, ITS and OP, SR and OP, CII and OP and CF
and OP. The results of this study provide important insights to policy-makers and
researchers to further understand the effect of the integration of total quality management
and supply chain management practices on operational performance. JMIs should
emphasize on LSP, EIC, SR, CII, ITS and CF; however, it is important to note that overconcentration
on CII may result in lower practicability of lean manufacturing. Policymakers
should encourage JMIs to improve their quality and supply chain systems which
may improve their product and service quality with lower cost. Lastly, limitations of the
current study and avenues for future research are discussed
Electrical label-free sensing of cardiac troponin biomarker: FET-based integration with substrate-gate coupling
No full textDoctor of Philosophy in Nanoelectronic EngineeringAcute myocardial infarction (AMI) is a leading cause of death worldwide despite the existence of therapy’s advances. Therefore, an early diagnosis method by using cardiac biomarkers is essential to enable correct countermeasures. Cardiac Troponin I (cTnI) is one of the cardiac biomarkers for early diagnosis of AMI and considered as ‘gold standard’ for cardiac muscle injury determination. The detection of cTnI through an electrical-based biosensor allows label-free detection by converting biomolecular binding event into a significant electrical signal via a semiconductor transducer. It utilizes
conductivity to specify the existence of biomolecules. One of the electrical-based
biosensors known as field-effect transistor (FET)-based biosensor has drawn much
attention for owning the concept of charge transduction; thus, allows early, high
sensitivity, high selectivity, and rapid diagnosis of the specific cardiac biomarker at low
concentrations. In this work, the zinc oxide (ZnO)-FET biosensor coupled with substrategate
has been designed and fabricated for the detection of cTnI biomarker. ZnO thin film,
as n-type biocompatible semiconductor material, and also as transducer was deposited via
sol-gel and spin coating techniques between p-type source and drain terminal on SOI
substrate, forming a p-n-p junction, a device capable of bio-sensing application. The
surface morphology of the thin film was characterized by using atomic force microscopy
(AFM) and field emission scanning electron microscopy (FESEM). The thin film, which
demonstrated hexagonal wurtzite phase as shown by X-ray diffraction (XRD) analysis
appropriate for biomolecules interaction. The surface of the ZnO thin film was
immobilized with cTnI monoclonal antibody (MAb-cTnI) as biological receptor via
covalent binding technique for capturing cTnI biomarker. The process was validated by
Fourier transform-infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The
device structure was simulated in Silvaco Atlas 2D-simulator, to elucidate its electrical
characteristic, by means of hole and electron concentration in the channel and buried
oxide/substrate interface, respectively. The device demonstrated a new strategy via
electrical characterization with the introduction of substrate-gate coupling that enhanced
the formation of hole conduction layer at the channel between drain and source region.
Finally, the biosensor shown significant increment in relative changes of drain current
level in a linear range of 6.2 to 16.5 % with the increase of positively charge cTnI
biomarker concentrations from 1 ng/ml to 10 μg/ml. The device sensitivity of the
detection is at 2.51 %·(g/ml)-1 with limit of detection (LOD) down to 3.24 pg/ml
Characterization of quartz crystal microbalance sensor for detection of bacteria inactivation after plasma treatment
No full textMaster of Science in Biomedical Electronic EngineeringThis thesis presents a study of frequency response for detection of inactive bacteria
using Quartz Crystal Microbalance sensor. The characteristics of frequency response
towards detection of bacteria were discussed. The Escherichia coli bacteria with
concentration x108 colony forming unit per milliliter were inactivated using new
sterilization device which is atmospheric pressure plasma jet. A sensor device was
constructed to monitor frequency response of bacteria in different condition by using 9
MHz quartz crystal. For detecting the bacteria sample, the sensor surface was prepared
using Self-Assemble Monolayer technique together with Escherichia coli antibody as
bioreceptor for antigen recognition. Quartz Crystal Microbalance sensor with gold
electrodes were mounted in oscillator circuit and exposed to room temperature. The
Transistor-transistor Logic oscillator circuit was utilized since it was able to drive the
Quartz Crystal Microbalance sensor in air and liquid. Only one side of the crystal were
exposed to the liquid sample by using static measurement. The measured of frequency
response were observed in order to investigated the interfacial behavior of bacteria
Escherichia coli on surface of sensor. The results show that the bacteria after
inactivation have higher frequency shifting than bacteria before plasma treatment. The
difference in frequency responses showed that bacteria inactivated by atmospheric
plasma device have increment of mass. These situations are caused by several factors
such as unspecific molecule presence inside inactive bacteria sample, types of
bioreceptor, surface roughness and condition of electrode surface. The analysis also
includes piezoelectric effects, experimental conditions and the characteristic of surface
roughness. From average result of 10 sensors device utilized in the experiment, 8 were
successful in bacteria detection. The detection also depends on condition of electrode
surface. Moreover, this system has the ability to detect bacteria active and inactive in
liquid situation
Critical components identification using analytic hierarchy process - a case study towards product design improvement
No full textMaster of Science in Manufacturing Systems EngineeringFailure of product during its operation may result unsatisfied customer. In order to maintain the high value of product, proper action such as maintainability measure and reliability is one of crucial part during product design improvement phase. In this phase, the identification of critical component that should be prioritized for product design improvement must be clearly identified. However, in current practices of product design improvement, the attention on identifying critical component has been neglected.
Therefore, to make this improvement process more effective and efficient, a decision model of critical component identification is proposed. The main objective of this proposed model is to identify the critical components towards product design improvement. The methodology of this study starts with the application of Component Classification Analysis (CCA) where the main components and support components is identified. Next, the result from the CCA is used as the input for Analytic Hierarchy Process (AHP). In this step, the input is compared by using pairwise comparison based on the criteria that has been chosen
which are clogged, breakdown and loose. A case study of two different types of staple guns is used to validate the developed decision model. Results from this research shows that there are five critical components which are compress spring, body, outlet spring, hammer and rivet in the staple gun should be prioritized for product design improvement. By having
this information, it will help the design team to focus on that particular component during
product design improvement
Allelopathic potential of essential oils isolated from local plants on common weeds found in Malaysian croplands
No full textDoctor of Philosophy in Biosystem EngineeringContinuous use of the synthetic herbicides to control weeds in agricultural production can have an adverse impact on the environment and the ecosystems creating safety and health concerns to the operators, consumers and the community. However, it is the resistance to the synthetic herbicides that developed in the targeted weeds and its consequent that provide strong justification for the need to develop an eco-friendly, natural and low risk but effective alternative bioherbicides. The study thus explores the benefits of using plant’s allelopathic potential that manifested in its essential oil, as an alternative herbicide. The research involved the isolation of the essential oils from eight selected plant species of Cupressus macrocarpa Hartweg. (Goldcrest), Melaleuca bracteata F. Muell. (Tea tree), Plectranthus amboinicus (Lour.) Spreng (Spanish
thyme), Cymbopogon nardus L. (Lemongrass), Pelargonium radula Cav. (Radula
geranium), Baeckea frutescens L. (Cucur atap), Murraya koenigii L. (Curry tree) and
Persicaria odorata (Lour.) Sojak (Kesum plant) by steam distillation. Isolated essential
oils were screened for their herbicidal activity as preemergence applied at three
concentrations on two major weed types (2 grassy and 2 broad leaves weed species)
grown under bioassay laboratory and pot culture conditions. The compounds were
characterized using GC-MS. The phytotoxic effects of the eight essential oils were also
evaluated on the four weeds as postemergence by analyzing the total chlorophyll
content, relative electrolyte leakage, cellular respiration and stomata mechanism in the
leaf membrane. The most effective essential oils were then evaluated as postemergence
by applying singly and in a combination of two essential oils on widely known weed
grown in the open field and compared with the known synthetic herbicide, Halexone
(H130) as a control. The best essential oils were selected based on their efficacy of more
than 70 % inhibition. The results showed that the oils isolated from C. macrocarpa, C.
nardus and P. radula were the most effective in inhibiting seed germination and
seedling growth completely in laboratory bioassay and caused the most severe effects
on weeds grown under the pot culture. GC-MS analysis showed monoterpene was the
most dominant and effective component of all essential oils followed by sesquiterpene
and phenylpropanoids. The phytotoxic experiment showed total chlorophyll content,
relative electrolyte leakage and cellular respiration were significantly affected by the
application of the bioherbicides. The effects increased by increasing the oil concentration. There was a significant influence of the essential oils on plant
membranes affecting the stomata mechanism, rupturing cell membrane, dissolution of
its contents which eventually kill the weeds. The application of essential oils as
postemergence herbicides to weed grown in the open field showed desirable efficiency
against the weeds as non-selected contact bioherbicides comparable with the
performance of the conventional synthetic herbicides H130. Application of the essential
oils formulated in combinations improved the phytotoxic effects as compared to using
oils singly. The combination of C. macrocarpa and P. radula at 5% each proved to
produce the best phytotoxic effects in suppressing weed population
