Abstract: The exploitation of flow pulsation in micro- and
mini-channels is a potentially useful technique for enhancing cooling
of high-end photonics and electronics systems. It is thought that
pulsation alters the thickness of the hydrodynamic and thermal
boundary layers, and hence affects the overall thermal resistance
of the heat sink. Although the fluid mechanics and heat transfer
are inextricably linked, it can be useful to decouple the parameters
to better understand the mechanisms underlying any heat transfer
enhancement. Using two-dimensional, two-component particle image
velocimetry, the current work intends to characterize the heat transfer
mechanisms in pulsating flow with a mean Reynolds number of
48 by experimentally quantifying the hydrodynamics of a generic
liquid-cooled channel geometry. Flows circulated through the test
section by a gear pump are modulated using a controller to achieve
sinusoidal flow pulsations with Womersley numbers of 7.45 and
2.36 and an amplitude ratio of 0.75. It is found that the transient
characteristics of the measured velocity profiles are dependent on the
speed of oscillation, in accordance with the analytical solution for
flow in a rectangular channel. A large velocity overshoot is observed
close to the wall at high frequencies, resulting from the interaction
of near-wall viscous stresses and inertial effects of the main fluid
body. The steep velocity gradients at the wall are indicative of
augmented heat transfer, although the local flow reversal may reduce
the upstream temperature difference in heat transfer applications.
While unsteady effects remain evident at the lower frequency, the
annular effect subsides and retreats from the wall. The shear rate at
the wall is increased during the accelerating half-cycle and decreased
during deceleration compared to steady flow, suggesting that the flow
may experience both enhanced and diminished heat transfer during
a single period. Hence, the thickness of the hydrodynamic boundary
layer is reduced for positively moving flow during one half of the
pulsation cycle at the investigated frequencies. It is expected that the
size of the thermal boundary layer is similarly reduced during the
cycle, leading to intervals of heat transfer enhancement.
Abstract: Present paper enumerates highlights of seasonal
variation in floristic composition and ecological strategies for the
management of ‘Gujar Tal’ at Jaunpur in tropical semi-arid region of
eastern U.P. (India). Total composition of macrophytes recorded was
47 from 26 families with maximum 6 plant species of Cyperaceae
from April, 2012 to March, 2013 at certain periodic intervals.
Maximum number of plants (39) was present during winter followed
by (37) rainy and (27) summer seasons. The distribution pattern
depicted that maximum number of plants (27) was of marshy and
swampy habitats usually transitional between land and water.
Abstract: The layered structure LiNi1/3Co1/3Mn1/3-xAlxO2 (x = 0 ~
0.04) series cathode materials were synthesized by a carbonate
co-precipitation method, followed by a high temperature calcination
process. The influence of Al substitution on the microstructure and
electrochemical performances of the prepared materials was
investigated by X-Ray diffraction (XRD), scanning electron
microscopy (SEM), and galvanostatic charge/discharge test. The
results show that the LiNi1/3Co1/3Mn1/3-xAlxO2 has a well-ordered
hexagonal α-NaFeO2 structure. Although the discharge capacity of
Al-doped samples decreases as x increases,
LiNi1/3Co1/3Mn1/3-0.02Al0.02O2 exhibits superior capacity retention at
high voltage (4.6 V). Therefore, LiNi1/3Co1/3Mn1/3-0.02Al0.02O2 is a
promising material for “green” vehicles.
Abstract: Recently developed cooperative diversity scheme
enables a terminal to get transmit diversity through the support of other
terminals. However, most of the introduced cooperative schemes have
a common fault of decreased transmission rate because the destination
should receive the decodable compositions of symbols from the source
and the relay. In order to achieve high data rate, we propose a
cooperative scheme that employs hierarchical modulation. This
scheme is free from the rate loss and allows seamless cooperative
communication.
Abstract: The irradiation of polymeric materials has received
much attention because it can produce diverse changes in chemical
structure and physical properties. Thus, studying the chemical and
structural changes of polymers is important in practice to achieve
optimal conditions for the modification of polymers. The effect of
gamma irradiation on the crystalline structure of poly(vinylidene
fluoride) (PVDF) has been investigated using differential scanning
calorimetry (DSC) and X-ray diffraction techniques (XRD). Gamma
irradiation was carried out in atmosphere air with doses between 100
kGy at 3,000 kGy with a Co-60 source. In the melting thermogram of
the samples irradiated can be seen a bimodal melting endotherm is
detected with two melting temperature. The lower melting
temperature is attributed to melting of crystals originally present and
the higher melting peak due to melting of crystals reorganized upon
heat treatment. These results are consistent with those obtained by
XRD technique showing increasing crystallinity with increasing
irradiation dose, although the melting latent heat is decreasing.
Abstract: The combination of multi–walled carbon nanotubes
(MWCNTs) with polymers offers an attractive route to reinforce the
macromolecular compounds as well as the introduction of new
properties based on morphological modifications or electronic
interactions between the two constituents. As they are only a few
nanometers in dimension, it offers ultra-large interfacial area per
volume between the nano-element and polymer matrix. Nevertheless,
the use of MWCNTs as a rough material in different applications has
been largely limited by their poor processability, insolubility, and
infusibility. Studies concerning the nanofiller reinforced polymer
composites are justified in an attempt to overcome these limitations.
This work presents one preliminary study of MWCNTs dispersion
into the PVDF homopolymer. For preparation, the composite
components were diluted in n,n-dimethylacetamide (DMAc) with
mechanical agitation assistance. After complete dilution, followed by
slow evaporation of the solvent at 60°C, the samples were dried.
Films of about 80 μm were obtained. FTIR and UV-Vis
spectroscopic techniques were used to characterize the
nanocomposites. The appearance of absorption bands in the FTIR
spectra of nanofilled samples, when compared to the spectrum of
pristine PVDF samples, are discussed and compared with the UV-Vis
measurements.
Abstract: The adjoint method has been used as a successful tool to
obtain sensitivity gradients in aerodynamic design and optimisation
for many years. This work presents an alternative approach to the
continuous adjoint formulation that enables one to compute gradients
of a given measure of merit with respect to control parameters other
than those pertaining to geometry. The procedure is then applied to
the steady 2–D compressible Euler and incompressible Navier–Stokes
flow equations. Finally, the results are compared with sensitivities
obtained by finite differences and theoretical values for validation.
Abstract: Interaction between mixing and crystallization is often
ignored despite the fact that it affects almost every aspect of the
operation including nucleation, growth, and maintenance of the
crystal slurry. This is especially pronounced in multiple impeller
systems where flow complexity is increased. By choosing proper
mixing parameters, what closely depends on the knowledge of the
hydrodynamics in a mixing vessel, the process of batch cooling
crystallization may considerably be improved. The values that render
useful information when making this choice are mixing time and
power consumption. The predominant motivation for this work was
to investigate the extent to which radial dual impeller configuration
influences mixing time, power consumption and consequently the
values of metastable zone width and nucleation rate. In this research,
crystallization of borax was conducted in a 15 dm3 baffled batch
cooling crystallizer with an aspect ratio (H/T) of 1.3. Mixing was
performed using two straight blade turbines (4-SBT) mounted on the
same shaft that generated radial fluid flow. Experiments were
conducted at different values of N/NJS ratio (impeller speed/
minimum impeller speed for complete suspension), D/T ratio
(impeller diameter/crystallizer diameter), c/D ratio (lower impeller
off-bottom clearance/impeller diameter), and s/D ratio (spacing
between impellers/impeller diameter). Mother liquor was saturated at
30°C and was cooled at the rate of 6°C/h. Its concentration was
monitored in line by Na-ion selective electrode. From the values of
supersaturation that was monitored continuously over process time, it
was possible to determine the metastable zone width and
subsequently the nucleation rate using the Mersmann’s nucleation
criterion. For all applied dual impeller configurations, the mixing
time was determined by potentiometric method using a pulse
technique, while the power consumption was determined using a
torque meter produced by Himmelstein & Co. Results obtained in
this investigation show that dual impeller configuration significantly
influences the values of mixing time, power consumption as well as
the metastable zone width and nucleation rate. A special attention
should be addressed to the impeller spacing considering the flow
interaction that could be more or less pronounced depending on the
spacing value.
Abstract: High double excitation of two-electron atoms has been
investigated using hyperpherical coordinates within a modified
adiabatic expansion technique. This modification creates a novel
fictitious force leading to a spontaneous exchange symmetry breaking
at high double excitation. The Pauli principle must therefore be
regarded as approximation valid only at low excitation energy.
Threshold electron scattering from high Rydberg states shows an
unexpected time reversal symmetry breaking. At threshold for double
escape we discover a broad (few eV) Cooper pair.
Abstract: Ultrasonic metal welding has been the subject of ongoing research and development, most recently concentrating on metal joining in miniature devices, for example to allow solder-free wire bonding. As well as at the small scale, there are also opportunities to research the joining of thicker sheet metals and to widen the range of similar and dissimilar materials that can be successfully joined using this technology. This study presents the design, characterisation and test of a lateral-drive ultrasonic metal spot welding device. The ultrasonic metal spot welding horn is modelled using finite element analysis (FEA) and its vibration behaviour is characterised experimentally to ensure ultrasonic energy is delivered effectively to the weld coupon. The welding stack and fixtures are then designed and mounted on a test machine to allow a series of experiments to be conducted for various welding and ultrasonic parameters. Weld strength is subsequently analysed using tensile-shear tests. The results show how the weld strength is particularly sensitive to the combination of clamping force and ultrasonic vibration amplitude of the welding tip, but there are optimal combinations of these and also limits that must be clearly identified.
Abstract: This paper applies recursive cointegration analysis to
examine the dynamic changes in Feldstein-Horioka saving-investment
(S-I) coefficients across China and the ASEAN-5 countries over time.
To the extent that the S-I coefficients measure international capital
mobility, the main empirical results are as follows. The recursive trace
statistics show that the investment- savings nexus varies in these six
countries. There is no cointegration between investment and savings in
three countries (China, Malaysia, and Singapore), which means that
the mobility of the capital markets in the three is high and that
domestic investment in them will be financed by the global pool of
capital. As to the other three countries (Indonesia, Thailand, and
Philippines), there is cointegration between investment and savings for
part of the sample period in the three, including before 2002 for
Thailand, before 2001 for Indonesia, and before 2002 for Philippines.
This shows these three countries achieved highly mobile and open
capital markets later.
Abstract: Centrifugal-casting machine is used in manufacturing
special machine components like multi-layer journal bearing used in
all internal combustion engine, steam, gas turbine and air craft turboengine
where isotropic properties and high precisions are desired.
Moreover, this machine can be used in manufacturing thin wall hightech
machine components like cylinder liners and piston rings of IC
engine and other machine parts like sleeves, and bushes. Heavy-duty
machine component like railway wheel can also be prepared by
centrifugal casting. A lot of technological developments are required
in casting process for production of good casted machine body and
machine parts. Usually defects like blowholes, surface roughness,
chilled surface etc. are found in sand casted machine parts. But these
can be removed by centrifugal casting machine using rotating
metallic die. Moreover, die rotation, its temperature control, and good
pouring practice can contribute to the quality of casting because of
the fact that the soundness of a casting in large part depends upon
how the metal enters into the mold or dies and solidifies. Poor
pouring practice leads to variety of casting defects such as
temperature loss, low quality casting, excessive turbulence, over
pouring etc. Besides these, handling of molten metal is very
unsecured and dangerous for the workers. In order to get rid of all
these problems, the need of an automatic pouring device arises. In
this research work, a robot assisted pouring device and a centrifugal
casting machine are designed, developed constructed and tested
experimentally which are found to work satisfactorily. The robot
assisted pouring device is further modified and developed for using it
in actual metal casting process. Lot of settings and tests are required
to control the system and ultimately it can be used in automation of
centrifugal casting machine to produce high-tech machine parts with
desired precision.
Abstract: The boundary layer separation and new active flow control of a NACA 0025 airfoil were studied experimentally. This new flow control is sometimes known as a co-flow jet (cfj) airfoil. This paper presents the fluctuating velocity in a wall jet over the co-flow jet airfoil subjected to an adverse pressure gradient and a curved surface. In these results, the fluctuating velocity at the inner part increasing by increased the angle of attack up to 12o and this has due to the jet energized, while the angle of attack 20o has different. The airfoil cord based Reynolds number has 105.
Abstract: This paper investigates the application of metallic
coatings on high fiber volume fraction carbon/epoxy polymer matrix
composites. For the grip of the metallic layer, a method of modifying
the surface of the composite by introducing a mixture of copper and
steel powder (filler powders) which can reduce the impact of thermal
spray particles. The powder was introduced to the surface at the time
of the forming. Arc spray was used to project the zinc coating layer.
The substrate was grit blasted to avoid poor adherence. The porosity, microstructure, and morphology of layers are
characterized by optical microscopy, SEM and image analysis. The
samples were studied also in terms of hardness and erosion resistance.
This investigation did not reveal any visible evidence damage to the
substrates. The hardness of zinc layer was about 25.94 MPa and the
porosity was around (∼6.70%). The erosion test showed that the zinc
coating improves the resistance to erosion. Based on the results
obtained, we can conclude that thermal spraying allows the production
of protective coating on PMC. Zinc coating has been identified as a
compatible material with the substrate. The filler powders layer
protects the substrate from the impact of hot particles and allows
avoiding the rupture of brittle carbon fibers.
Abstract: Smart metering and demand response are gaining
ground in industrial and residential applications. Smart Appliances
have been given concern towards achieving Smart home. The success
of Smart grid development relies on the successful implementation of
Information and Communication Technology (ICT) in power sector.
Smart Appliances have been the technology under development and
many new contributions to its realization have been reported in the
last few years. The role of ICT here is to capture data in real time,
thereby allowing bi-directional flow of information/data between
producing and utilization point; that lead a way for the attainment of
Smart appliances where home appliances can communicate between
themselves and provide a self-control (switch on and off) using the
signal (information) obtained from the grid. This paper depicts the
background on ICT for smart appliances paying a particular attention
to the current technology and identifying the future ICT trends for
load monitoring through which smart appliances can be achieved to
facilitate an efficient smart home system which promote demand
response program. This paper grouped and reviewed the recent
contributions, in order to establish the current state of the art and
trends of the technology, so that the reader can be provided with a
comprehensive and insightful review of where ICT for smart
appliances stands and is heading to. The paper also presents a brief
overview of communication types, and then narrowed the discussion
to the load monitoring (Non-intrusive Appliances Load Monitoring
‘NALM’). Finally, some future trends and challenges in the further
development of the ICT framework are discussed to motivate future
contributions that address open problems and explore new
possibilities.
Abstract: The recent instability in economy was found to be
influencing the situation in Malaysia whether directly or indirectly.
Taking that into consideration, the government needs to find the best
approach to balance its citizen’s socio-economic strata level urgently.
Through education platform is among the efforts planned and acted
upon for the purpose of balancing the effects of the influence,
through the exposure of social entrepreneurial activity towards youth
especially those in higher institution level. Armed with knowledge
and skills that they gained, with the support by entrepreneurial
culture and environment while in campus; indirectly, the students will
lean more on making social entrepreneurship as a career option when
they graduate. Following the issues of marketability and workability
of current graduates that are becoming dire, research involving how
far the willingness of student to create social innovation that
contribute to the society without focusing solely on personal gain is
relevant enough to be conducted. With that, this research is
conducted with the purpose of identifying the level of entrepreneurial
intention and social entrepreneurship among higher institution
students in Malaysia. Stratified random sampling involves 355
undergraduate students from five public universities had been made
as research respondents and data were collected through surveys. The
data was then analyzed descriptively using min score and standard
deviation. The study found that the entrepreneurial intention of higher
education students are on moderate level, however it is the contrary
for social entrepreneurship activities, where it was shown on a high
level. This means that while the students only have moderate level of
willingness to be a social entrepreneur, they are very committed to
created social innovation through the social entrepreneurship
activities conducted. The implication from this study can be
contributed towards the higher institution authorities in prediction the
tendency of student in becoming social entrepreneurs. Thus, the
opportunities and facilities for realizing the courses related to social
entrepreneurship must be created expansively so that the vision of
creating as many social entrepreneurs as possible can be achieved.
Abstract: We present an approach to triangle mesh simplification
designed to be executed on the GPU. We use a quadric error metric
to calculate an error value for each vertex of the mesh and order all
vertices based on this value. This step is followed by the parallel
removal of a number of vertices with the lowest calculated error
values. To allow for the parallel removal of multiple vertices we use
a set of per-vertex boundaries that prevent mesh foldovers even when
simplification operations are performed on neighbouring vertices. We
execute multiple iterations of the calculation of the vertex errors,
ordering of the error values and removal of vertices until either a
desired number of vertices remains in the mesh or a minimum error
value is reached. This parallel approach is used to speed up the
simplification process while maintaining mesh topology and avoiding
foldovers at every step of the simplification.
Abstract: The maintenance of work rolls in hot strip processing
has been lengthy and difficult tasks for hot strip manufacturer
because heavy work rolls have to be taken out of the production line,
which could take hours. One way to increase the time between
maintenance is to improve the effectiveness of the work roll cooling
system such that the wear and tear more slowly occurs, while the
operation cost is kept low. Therefore, this study aims to improve the
work roll cooling system by providing the manufacturer the
relationship between the work-roll temperature reduced by cooling
and the water flow that can help manufacturer determining the more
effective water flow of the cooling system. The relationship is found
using simulation with a systematic process adjustment so that the
satisfying quality of product is achieved. Results suggest that the
manufacturer could reduce the water flow by 9% with roughly the
same performance. With the same process adjustment, the feasibility
of finishing-mill-stand reduction is also investigated. Results suggest
its possibility.
Abstract: Voltage level must be raised in order to deliver the
produced energy to the consumption zones with less loss and less
cost. Power transformers used to raise or lower voltage are important
parts of the energy transmission system. Power transformers used in
switchgear and power generation plants stay in human's intensive
habitat zones as a result of expanding cities. Accordingly, noise
levels produced by power transformers have begun more and more
important and they have established itself as one of the research field.
In this research, the noise cause on transformers has been
investigated, it's causes has been examined and noise measurement
techniques have been introduced. Examples of transformer noise test
results are submitted and precautions to be taken were discussed for
the purpose of decreasing of the noise which will occurred by
transformers.
Abstract: Cloud computing can reduce the start-up expenses of implementing EHR (Electronic Health Records). However, many of the healthcare institutions are yet to implement cloud computing due to the associated privacy and security issues. In this paper, we analyze the challenges and opportunities of implementing cloud computing in healthcare. We also analyze data of over 5000 US hospitals that use Telemedicine applications. This analysis helps to understand the importance of smart phones over the desktop systems in different departments of the healthcare institutions. The wide usage of smartphones and cloud computing allows ubiquitous and affordable access to the health data by authorized persons, including patients and doctors. Cloud computing will prove to be beneficial to a majority of the departments in healthcare. Through this analysis, we attempt to understand the different healthcare departments that may benefit significantly from the implementation of cloud computing.