Abstract: This paper presents the electromagnetic interference
(EMI) shielding effectiveness of rice husk and carbon nanotubes
(RHCNTs) composites in the X-band region (8.2-12.4 GHz). The
difference weight ratio of carbon nanotubes (CNTs) were mix with
the rice husk. The rectangular waveguide technique was used to
measure the complex permittivity of the RHCNTs composites
materials. The complex permittivity is represented in terms of both
the real and imaginary parts of permittivity in X-band frequency. The
conductivity of RHCNTs shows increasing when the ratio of CNTs
mixture increases. The composites materials were simulated using
Computer Simulation Technology (CST) Microwave Studio
simulation software. The shielding effectiveness of RHCNTs and
pure rice husk was compared. The highest EMI SE of 30 dB is
obtained for RHCNTs composites of 10 wt % CNTs with 10mm
thickness.
Abstract: With advances in solid-state power electronic devices
and microprocessors, various pulse-width-modulation (PWM)
techniques have been developed for industrial applications. This
paper presents the comparison of two different PWM techniques, the
sinusoidal PWM (SPWM) technique and the space-vector PWM
(SVPWM) technique applied to two level VSI for micro grid
applications. These two methods are compared by discussing their
ease of implementation and by analyzing the output harmonic spectra
of various output voltages (line-to-neutral voltages, and line-to-line
voltages) and their total harmonic distortion (THD). The SVPWM
technique in the under-modulation region can increase the
fundamental output voltage by 15.5% over the SPWM technique.
Abstract: A noble low NOx combustion technology, based on
partial oxidation combustion concept in a fuel rich combustion zone, is
successfully applied in this research. The burner is designed such that
a portion of fuel is heated and pre-vaporized in the furnace then
injected into a fuel rich combustion zone so that a partial oxidation
reaction occurs. The effects of equivalence ratio, thermal load, and
fuel distribution ratio on the emissions of NOx and CO are
experimentally investigated. This newly developed combustion
technology showed very low NOx emission level, about 12 ppm, when
light oil is used as a fuel.
Abstract: Folic acid (FA) is known to be an important
supplement to prevent neural tube defect (NTD) in pregnant women.
Similar to some commercial formulations, sodium bicarbonate
solution is used as a solvent for FA. This work uses the antisolvent
vapour precipitation (AVP), incorporating ethanol vapour as the
convective drying medium in place of air to produce branch-like
micro-structure FA particles. Interestingly, the dissolution rate of the
resultant particle is 2-3 times better than the particle produce from
conventional air drying due to the higher surface area of particles
produced. The higher dissolution rate could possibly improve the
delivery and absorption of FA in human body. This application could
potentially be extended to other commercial products, particularly in
less soluble drugs to improve its solubility.
Abstract: Immunomodulators are substances that alter immune
system via dynamic regulation of messenger molecules. It can be
divided into immunostimulant and immunosuppressant. It can help to
increase immunity of people with a low immune system, and also can
help to normalize an overactive immune system. Aim of this study is
to investigate the effects of in vitro exposure to low and high doses of
several immunomodulators which include caffeine, kaloba and
quercetin on antigen-stimulated whole blood culture cytokine
production. Whole blood samples were taken from 5 healthy males
(age: 32 ± 12 years; weight: 75.7 ± 6.1 kg; BMI: 24.3 ± 1.5 kg/m2)
following an overnight fast with no vigorous activity during the
preceding 24 h. The whole blood was then stimulated with 50 μl of
100 x diluted Pediacel vaccine and low or high dose of
immunomodulators in the culture plate. After 20 h incubation (5%
CO2, 37°C), it was analysed using the Evidence Investigator to
determine the production of cytokines including IL-2, IL-4, IL-10,
IFN-γ, and IL-1α. Caffeine and quercetin showed a tendency towards
decrease cytokine production as the doses were increased. On the
other hand, an upward trend was evident with kaloba, where a high
dose of kaloba seemed to increase the cytokine production. In
conclusion, we found that caffeine and quercetin have potential as
immunosuppressant and kaloba as immunostimulant.
Abstract: The objective of the study was to select the survival of
probiotic strains when exposed to acidic and bile salts condition. Four
probiotic strains Lactobacillus casei subsp. rhamnosus TISTR 047,
Lactobacillus casei TISTR 1500, Lactobacillus acidophilus TISTR
1338 and Lactobacillus plantarum TISTR 1465 were cultured in
MRS broth and incubated at 35ºC for 15 hours before being inoculated
into acidic condition 5 M HCl, pH 2 for 2 hours and bile salt 0.3%,
pH 5.8 for 8 hour. The survived probiotics were counted in MRS agar.
Among four stains, Lactobacillus casei subsp. rhamnosus TISTR 047
was the highest tolerance specie. Lactobacillus casei subsp.
rhamnosus TISTR 047 reduced 6.74±0.07 log CFU/ml after growing
in acid and 5.52±0.05 log CFU/ml after growing in bile salt. Then,
double emulsion of microorganisms was chosen to encapsulate before
spray drying. Spray drying was done with the inlet temperature 170ºC
and outlet temperature 80ºC. The results showed that the survival of
encapsulated Lactobacillus casei subsp. rhamnosus TISTR 047 after
spray drying decreased from 9.63 ± 0.32 to 8.31 ± 0.11 log CFU/ml
comparing with non-encapsulated, 9.63 ± 0.32 to 4.06 ± 0.08 log
CFU/ml. Therefore, Lactobacillus casei subsp. rhamnosus TISTR 047
would be able to survive in gastrointestinal and spray drying condition.
Abstract: In this numerical study, we want to present the design
of highly efficient extruded-type heat sink. The symmetrically
arranged extruded-type heat sinks are used instead of a single extruded
or swaged-type heat sink. In this parametric study, the maximum
temperatures, the base temperatures between heaters, and the heat
release rates were investigated with respect to the arrangements of heat
sources, air flow rates, and amounts of heat input. Based on the results
we believe that the use of both side of heat sink is to be much better for
release the heat than the use of single side. Also from the results, it is
believed that the symmetric arrangement of heat sources is
recommended to achieve a higher heat transfer from the heat sink.
Abstract: In this study, the evaluation of thermal stability of the
micrometer-sized silica particle reinforced epoxy composite was
carried out through the measurement of thermal expansion coefficient
and Young’s modulus of the specimens. For all the specimens in this
study from the baseline to those containing 50 wt% silica filler, the
thermal expansion coefficients and the Young’s moduli were
gradually decreased down to 20% and increased up to 41%,
respectively. The experimental results were compared with fillervolume-
based simple empirical relations. The experimental results of
thermal expansion coefficients correspond with those of Thomas’s
model which is modified from the rule of mixture. However, the
measured result for Young’s modulus tends to be increased slightly.
The differences in increments of the moduli between experimental and
numerical model data are quite large.
Abstract: During welding, the amount of heat present in weld
zones determines the quality of weldment produced. Thus, the heat
distribution characteristics and its magnitude in weld zones with
respect to process variables such as tool pin-shoulder rotational and
traveling speed during welding is analyzed using thermal finite
element analyses method. For this purpose, transient thermal finite
element analyses are performed to model the temperatures
distribution and its quantities in weld-zones with respect to process
variables such as rotational speed and traveling speed during welding.
Commercially available software Altair HyperWork is used to model
three-dimensional tool pin-shoulder vs. workpieces and to simulate
the friction stir process. The results show that increasing tool
rotational speed, at a constant traveling speed, will increase the
amount of heat generated in weld-zones. In contrary, increasing
traveling speed, at constant tool pin-shoulder rotational speeds, will
reduce the amount of heat generated in weld zones.
Abstract: In this paper, an edge-strength guided multiscale
retinex (EGMSR) approach will be proposed for color image contrast
enhancement. In EGMSR, the pixel-dependent weight associated with
each pixel in the single scale retinex output image is computed
according to the edge strength around this pixel in order to prevent
from over-enhancing the noises contained in the smooth dark/bright
regions. Further, by fusing together the enhanced results of EGMSR
and adaptive multiscale retinex (AMSR), we can get a natural fused
image having high contrast and proper tonal rendition. Experimental
results on several low-contrast images have shown that our proposed
approach can produce natural and appealing enhanced images.
Abstract: Because of high thermal efficiency and low CO2
emission, diesel engines are being used widely in many industrial
fields although it makes many PM and NOx which give both human
health and environment a negative effect. NOx regulations for diesel
engines, however, are being strengthened and it is impossible to meet
the emission standard without NOx reduction devices such as SCR
(Selective Catalytic Reduction), LNC (Lean NOx Catalyst), and LNT
(Lean NOx Trap). Among the NOx reduction devices, urea-SCR
system is known as the most stable and efficient method to solve the
problem of NOx emission. But this device has some issues associated
with the ammonia slip phenomenon which is occurred by shortage of
evaporation and thermolysis time, and that makes it difficult to achieve
uniform distribution of the injected urea in front of monolith.
Therefore, this study has focused on the mixing enhancement between
urea and exhaust gases to enhance the efficiency of the SCR catalyst
equipped in catalytic muffler by changing inlet gas temperature and
spray conditions to improve the spray uniformity of the urea water
solution. Finally, it can be found that various parameters such as inlet
gas temperature and injector and injection angles significantly affect
the evaporation and mixing of the urea water solution with exhaust
gases, and therefore, optimization of these parameters are required.
Abstract: As Malaysia aims to be a developed country by year 2020; the construction industry has since been identified as a major catalyst for the country to attain the status. It is one of the sectors that contribute to most environmental pollutions. It is, therefore, important for the industry to implement sustainable construction practices to reduce the negative impacts that it has on the environment. However, most Malaysian developers have placed much focus on market demand and economic factors; neglecting the need for attention on environmental issues. The practice of sustainable construction is deemed to be an obstacle to achieve short-term economic goals due to the higher cost incurred in the operations. Hence, choices need to be made and a balance needs to be struck in weighing the long-term environmental benefits against immediate economic factors. This paper discusses the challenges faced by Malaysian developers in adopting sustainable practices in the construction industry and the cause of these challenges. It also looks into the achievements and breakthroughs that developers in Malaysia have achieved so far. The paper aims explores the long-term benefits of sustainable practices that would potentially raise awareness on the feasibility and economic potential of sustainable construction.
Abstract: When it comes to last, it is regarded as the critical foundation of shoe design and development. Not only the last relates to the comfort of shoes wearing but also it aids the production of shoe styling and manufacturing. In order to enhance the efficiency and application of last development, a computer aided methodology for customized last form designs is proposed in this study. The reverse engineering is mainly applied to the process of scanning for the last form. Then the minimum energy is used for the revision of surface continuity, the surface of the last is reconstructed with the feature curves of the scanned last. When the surface of a last is reconstructed, based on the foundation of the proposed last form reconstruction module, the weighted arithmetic mean method is applied to the calculation on the shape morphing which differs from the grading for the control mesh of last, and the algorithm of subdivision is used to create the surface of last mesh, thus the feet-fitting 3D last form of different sizes is generated from its original form feature with functions remained. Finally, the practicability of the proposed methodology is verified through later case studies.
Abstract: For Common R or R-L load to apply arbitrary voltage,
the bridge traditional inverters don’t have any difficulties by PWM
method. However for driving some piezoelectric actuator, arbitrary
voltage not a pulse but a steady voltage should be applied.
Piezoelectric load is considered as R-C load and its voltage does not
decrease even though the applied voltage decreases. Therefore it needs
some special inverter with circuit that can discharge the capacitive
energy. Especially for unidirectional arbitrary voltage driving like as
sine wave, it becomes more difficult problem. In this paper, a charge
and discharge circuit for unidirectional arbitrary voltage driving for
piezoelectric actuator is proposed. The circuit has charging and
discharging switches for increasing and decreasing output voltage.
With the proposed simple circuit, the load voltage can have any
unidirectional level with tens of bandwidth because the load voltage
can be adjusted by switching the charging and discharging switch
appropriately. The appropriateness is proved from the simulation of
the proposed circuit.
Abstract: Photoacoustic imaging (PAI) is a non-invasive and
non-ionizing imaging modality that combines the absorption contrast
of light with ultrasound resolution. Laser is used to deposit optical
energy into a target (i.e., optical fluence). Consequently, the target
temperature rises, and then thermal expansion occurs that leads to
generating a PA signal. In general, most image reconstruction
algorithms for PAI assume uniform fluence within an imaging object.
However, it is known that optical fluence distribution within the
object is non-uniform. This could affect the reconstruction of PA
images. In this study, we have investigated the influence of optical
fluence distribution on PA back-propagation imaging using finite
element method. The uniform fluence was simulated as a triangular
waveform within the object of interest. The non-uniform fluence
distribution was estimated by solving light propagation within a
tissue model via Monte Carlo method. The results show that the PA
signal in the case of non-uniform fluence is wider than the uniform
case by 23%. The frequency spectrum of the PA signal due to the
non-uniform fluence has missed some high frequency components in
comparison to the uniform case. Consequently, the reconstructed
image with the non-uniform fluence exhibits a strong smoothing
effect.
Abstract: Surplus electricity can be converted into potential energy via pumped hydroelectric storage for future usage. Similarly, thermo-electric energy storage (TEES) uses heat pumps equipped with thermal storage to convert electrical energy into thermal energy; the stored energy is then converted back into electrical energy when necessary using a heat engine. The greatest advantage of this method is that, unlike pumped hydroelectric storage and compressed air energy storage, TEES is not restricted by geographical constraints. In this study, performance variation of the TEES according to the changes in cold-side storage temperature was investigated by simulation method.
Abstract: In this paper, we propose a smart music player that combines the musical genre classification and the spatial audio processing. The musical genre is classified based on content analysis of the musical segment detected from the audio stream. In parallel with the classification, the spatial audio quality is achieved by adding an artificial reverberation in a virtual acoustic space to the input mono sound. Thereafter, the spatial sound is boosted with the given frequency gains based on the musical genre when played back. Experiments measured the accuracy of detecting the musical segment from the audio stream and its musical genre classification. A listening test was performed based on the virtual acoustic space based spatial audio processing.
Abstract: An alternative approach is proposed to develop the analytic solution for one dimensional heat conduction with one mixed type boundary condition and general time-dependent heat transfer coefficient. In this study, the physic meaning of the solution procedure is revealed. It is shown that the shifting function takes the physic meaning of the reciprocal of Biot function in the initial time. Numerical results show the accuracy of this study. Comparing with those given in the existing literature, the difference is less than 0.3%.
Abstract: The impact deformation and fracture behaviour of cobalt-based Haynes 188 superalloy are investigated by means of a split Hopkinson pressure bar. Impact tests are performed at strain rates ranging from 1×103 s-1 to 5×103 s-1 and temperatures between 25°C and 800°C. The experimental results indicate that the flow response and fracture characteristics of cobalt-based Haynes 188 superalloy are significantly dependent on the strain rate and temperature. The flow stress, work hardening rate and strain rate sensitivity all increase with increasing strain rate or decreasing temperature. It is shown that the impact response of the Haynes 188 specimens is adequately described by the Zerilli-Armstrong fcc model. The fracture analysis results indicate that the Haynes 188 specimens fail predominantly as the result of intensive localised shearing. Furthermore, it is shown that the flow localisation effect leads to the formation of adiabatic shear bands. The fracture surfaces of the deformed Haynes 188 specimens are characterised by dimple- and / or cleavage-like structure with knobby features. The knobby features are thought to be the result of a rise in the local temperature to a value greater than the melting point.
Abstract: This study aim at the influence of college students’ exercise and leisure motivations on the leisure benefits while using the leisure involvement as a moderator. Whereby, the research tools used in this study included the application of leisure motivation scale, leisure involvement scale and leisure benefits scale, and a hierarchical regression analysis was performed by using a questionnaire-based survey, in which, a total of 1,500 copies of questionnaires were administered and 917 valid questionnaires were obtained, achieving a response rate of 61.13%. Research findings explore that leisure involvement has a moderating effect on the relationship between the leisure motivation and leisure benefits.