Abstract: This paper describes an experimental, theoretical
model and numerical study of concentrated vortex flow past a sphere
in a hydraulic check valve. The phenomenon of the rotation of the
ball around the axis of the device through which liquid flows has
been found. That is, due to the rotation of the sphere in the check
valve vibration is caused. We observe the rotation of the sphere
around the longitudinal axis of the check valve. This rotation is
induced by a vortex shedding from the sphere. We will discuss
computational simulation and experimental investigations of this
strong sphere rotation. The frequency of the sphere vibration and
interaction with the check valve wall has been measured as a function
of the wide range Reynolds Number. The validity of the
computational simulation and of the assumptions on which it is based
has been proved experimentally. This study demonstrates the
possibility to control the vibrations in a hydraulic system and proves
to be very effective suppression of the self-excited vibration.
Abstract: We developed a method based on quasi-molecular
modelling to simulate the fall of water drops on horizontally smooth
and rough surfaces. Each quasi-molecule was a group of particles
that interacted in a fashion entirely analogous to classical Newtonian
molecular interactions. When a falling water droplet was simulated at
low impact velocity on both smooth and rough surfaces, the droplets
moved periodically (i.e. the droplets moved up and down for a
certain period, finally they stopped moving and reached a steady
state), spreading and recoiling without splash or break-up. Spreading
rates of falling water droplets increased rapidly as time increased
until the spreading rate reached its steady state at time t ~ 0.25 s for
rough surface and t ~ 0.40 s for smooth surface. The droplet height
above both surfaces decreased as time increased, remained constant
after the droplet diameter attained a maximum value and reached its
steady state at time t ~ 0.4 s. However, rough surface had higher
spreading rates of falling water droplets and lower height on the
surface than smooth one.
Abstract: Helical milling operations are used to generate or
enlarge boreholes by means of a milling tool. The bore diameter can be
adjusted through the diameter of the helical path. The kinematics of
helical milling on a three axis machine tool is analysed firstly. The
relationships between processing parameters, cutting tool geometry
characters with machined hole feature are formulated. The feed motion
of the cutting tool has been decomposed to plane circular feed and
axial linear motion. In this paper, the time varying cutting forces acted
on the side cutting edges and end cutting edges of the flat end cylinder
miller is analysed using a discrete method separately. These two
components then are combined to produce the cutting force model
considering the complicated interaction between the cutters and
workpiece. The time varying cutting force model describes the
instantaneous cutting force during processing. This model could be
used to predict cutting force, calculate statics deflection of cutter and
workpiece, and also could be the foundation of dynamics model and
predicting chatter limitation of the helical milling operations.
Abstract: Based on a long-term vegetation index dataset of NDVI and meteorological data from 68 meteorological stations in the Qinghai-Tibet plateau and their relations with major climate factors were analyzed. The results show the following: 1) The linear trends of temperature in the Qinghai-Tibet plateau indicate that the temperature in the plateau generally increased, but it rose faster in the last 20 years. 2) The most significant NDVI increase occurred in the eastern and southern plateau. However, the western and northern plateau demonstrate a decreasing trend. 3) There is a significant positive linear correlation between NDVI and temperature and a negative correlation between NDVI and mean wind speed. However, no significant statistical relationship was found between NDVI and relative humidity, precipitation or sunshine duration.4) The changes in NDVI for the plateau are driven by temperature-precipitation, but for the desert and forest areas, the relation changes to precipitation-temperature-wind velocity and wind velocity-temperature-precipitation.
Abstract: The rate of production of main products of the Fischer-Tropsch reactions over Fe/HZSM5 bifunctional catalyst in a fixed bed reactor is investigated at a broad range of temperature, pressure, space velocity, H2/CO feed molar ratio and CO2, CH4 and water flow rates. Model discrimination and parameter estimation were performed according to the integral method of kinetic analysis. Due to lack of mechanism development for Fisher – Tropsch Synthesis on bifunctional catalysts, 26 different models were tested and the best model is selected. Comprehensive one and two dimensional heterogeneous reactor models are developed to simulate the performance of fixed-bed Fischer – Tropsch reactors. To reduce computational time for optimization purposes, an Artificial Feed Forward Neural Network (AFFNN) has been used to describe intra particle mass and heat transfer diffusion in the catalyst pellet. It is seen that products' reaction rates have direct relation with H2 partial pressure and reverse relation with CO partial pressure. The results show that the hybrid model has good agreement with rigorous mechanistic model, favoring that the hybrid model is about 25-30 times faster.
Abstract: A self-association model has been used to understand
the concentration dependence of free energy of mixing (GM), heat of
mixing (HM), entropy of mixing (SM), activity (a) and microscopic
structures, such as concentration fluctuation in long wavelength limit
(Scc(0)) and Warren-Cowley short range order parameter ( 1
α )for Cu-
Tl molten alloys at 1573K. A comparative study of surface tension of
the alloys in the liquid state at that temperature has also been carried
out theoretically as function of composition in the light of Butler-s
model, Prasad-s model and quasi-chemical approach. Most of the
computed thermodynamic properties have been found in agreement
with the experimental values. The analysis reveals that the Cu-Tl
molten alloys at 1573K represent a segregating system at all
concentrations with moderate interaction. Surface tensions computed
from different approaches have been found to be comparable to each
other showing increment with the composition of copper.
Abstract: Computer-based decision support (CDSS) systems can
deliver real patient care and increase chances of long-term survival in
areas of chronic disease management prone to poor control. One such
CDSS, for the management of warfarin, is described in this paper and
the outcomes shown. Data is derived from the running system and
show a performance consistently around 20% better than the
applicable guidelines.
Abstract: In this study, the conversion of n-pentane to aromatics is investigated on HZSM-5 zeolites modified by Ga ion-exchange and silylation using tetraethyl orthosilicate (TEOS) via chemical liquid deposition (CLD). The effect of SiO2/Al2O3 ratios of HZSM-5 was also studied. Parameters in preparing catalysts i.e. TEOS loading and cycles of deposition were varied to obtain the optimal condition for enhancing p-xylene selectivity. The highest p-xylene selectivity 99.7% was achieved when the amount of TEOS was 20 vol.%.The catalysts were characterized by TPD, TPO, XRF, and BET. Results show that the conversion of n-pentane was influenced remarkably by the SiO2/Al2O3 ratios of HZSM-5. The highest p-xylene selectivity 99.7% was achieved when the amount of TEOS was 20 vol.%. And cycles of deposition greatly improves HZSM-5 shape-selectivity.
Abstract: In recent years, the number of natural disasters in the world has occurred frequently. After a strong earthquake occurs, multiple disasters due to tsunami, strong aftershocks or heavy snow can possible to occur. To prevent a secondary disaster and to save a life, the quick inspection of the damaged building is necessary. This paper investigated on a possibility of post earthquake quick inspection of damaged building by ordinary people which used the European Macro- Seismic Scale 1998 (EMS-98).
Abstract: The implementations of green roof have been widely
used in the developed countries such as Germany, United Kingdom,
United States and Canada. Green roof have many benefits such as
aesthetic and economic value, ecological gain which are optimization
of storm water management, urban heat island mitigation and energy
conservation. In term of pollution, green roof can control the air and
noise pollution in urban cities. The application of green roof in
Malaysian building has been studied with the previous work of green
roof either in Malaysia or other Asian region as like Indonesia,
Singapore, Thailand, Taiwan and several other countries that have
similar climate and environment as in Malaysia. These technologies
of adapting green roof have been compared to the Green Building
Index (GBI) of Malaysian buildings. The study has concentrated on
the technical aspect of green roof system having focused on i) waste
& recyclable materials ii) types of plants and method of planting and
iii) green roof as tool to reduce storm water runoff. The finding of
these areas will be compared to the suitability in achieving good
practice of the GBI in Malaysia. Results show that most of the
method are based on the countries own climate and environment.
This suggests that the method of using green roof must adhere to the
tropical climate of Malaysia. Suggestion of this research will be
viewed in term of the sustainability of the green roof. Further
research can be developed to implement the best method and
application in Malaysian climate especially in urban cities and
township.
Abstract: This paper is concerned with an improved algorithm
based on the piecewise-smooth Mumford and Shah (MS) functional
for an efficient and reliable segmentation. In order to speed up
convergence, an additional force, at each time step, is introduced
further to drive the evolution of the curves instead of only driven by
the extensions of the complementary functions u + and u - . In our
scheme, furthermore, the piecewise-constant MS functional is
integrated to generate the extra force based on a temporary image that
is dynamically created by computing the union of u + and u - during
segmenting. Therefore, some drawbacks of the original algorithm,
such as smaller objects generated by noise and local minimal problem
also are eliminated or improved. The resulting algorithm has been
implemented in Matlab and Visual Cµ, and demonstrated efficiently
by several cases.
Abstract: benzo[b][1,4]oxazines have been synthesized in good
to excellent yields in the presence of the ionic liquid 1-butyl-3-
methylimidazolium bromide [bmim]Br under relatively mild
conditions without any added catalyst, the reaction workup is simple
and the ionic liquid can be easily separated from the product and
reused.
Abstract: In the crack growth analysis, the Stress Intensity
Factor (SIF) is a fundamental prerequisite. In the present study, the
mode I stress intensity factor (SIF) of three-dimensional penny-
Shaped crack is obtained in an isotropic elastic cylindrical medium
with arbitrary dimensions under arbitrary loading at the top of the
cylinder, by the semi-analytical method based on the Rayleigh-Ritz
method. This method that is based on minimizing the potential
energy amount of the whole of the system, gives a very close results
to the previous studies. Defining the displacements (elastic fields) by
hypothetical functions in a defined coordinate system is the base of
this research. So for creating the singularity conditions at the tip of
the crack the appropriate terms should be found.
Abstract: A seismic isolation pad produced by utilizing the scrap
tire rubber which contains interleaved steel reinforcing cords has been
proposed. The steel cords are expected to function similar to the steel
plates used in conventional laminated rubber bearings. The scrap tire
rubber pad (STRP) isolator is intended to be used in low rise
residential buildings of highly seismic areas of the developing
countries. Experimental investigation was conducted on unbonded
STRP isolators, and test results provided useful information including
stiffness, damping values and an eventual instability of the isolation
unit. Finite element analysis (FE analysis) of STRP isolator was
carried out on properly bonded samples. These types of isolators
provide positive incremental force resisting capacity up to shear strain
level of 155%. This paper briefly discusses the force deformation
behavior of bonded STRP isolators including stability of the isolation
unit.
Abstract: Sol-gel method has been used to fabricate
nanocomposite films on glass substrates composed halloysite clay
mineral and nanocrystalline TiO2. The methodology for the synthesis
involves a simple chemistry method utilized nonionic surfactant
molecule as pore directing agent along with the acetic acid-based solgel
route with the absence of water molecules. The thermal treatment
of composite films at 450oC ensures elimination of organic material
and lead to the formation of TiO2 nanoparticles onto the surface of
the halloysite nanotubes. Microscopy techniques and porosimetry
methods used in order to delineate the structural characteristics of the
materials. The nanocomposite films produced have no cracks and
active anatase crystal phase with small crystallite size were deposited
on halloysite nanotubes. The photocatalytic properties for the new
materials were examined for the decomposition of the Basic Blue 41
azo dye in solution. These, nanotechnology based composite films
show high efficiency for dye’s discoloration in spite of different
halloysite quantities and small amount of halloysite/TiO2 catalyst
immobilized onto glass substrates. Moreover, we examined the
modification of the halloysite/TiO2 films with silver particles in order
to improve the photocatalytic properties of the films. Indeed, the
presence of silver nanoparticles enhances the discoloration rate of the
Basic Blue 41 compared to the efficiencies obtained for unmodified
films.
Abstract: A novel interpolation scheme to extend usable spectrum
and upconvert in high performance D/A converters is addressed in this
paper. By adjusting the pulse width of cycle and the production circuit
of code, the expansion code is a null code or complementary code that
is interpolation process. What the times and codes of interpolation
decide DAC works in one of a normal mode or multi-mixer mode
so that convert the input digital data signal into normal signal or a
mixed analog signal having a mixer frequency that is higher than the
data frequency. Simulation results show that the novel scheme and
apparatus most extend the usable frequency spectrum into fifth to
sixth Nyquist zone beyond conventional DACs.
Abstract: An experiment was performed with a 24.5 MeV 14N
beam on a 12C target in the cyclotron DC-60 located in Astana,
Kazakhstan, to study the elastic scattering of 14N on 12C; the
scattering was also analyzed at different energies for tracking the
phenomenon of remarkable structure at large angles. Its aims were to
extend the measurements to very large angles, and attempt to
uniquely identify the elastic scattering potential. Good agreement
between the theoretical and experimental data has been obtained with
suitable optical potential parameters. Optical model calculations with
l -dependent imaginary potentials were also applied to the data and
relatively good agreement was found.
Abstract: In this study, mechanically alloyed Al 2024 powder is
densified by conventional sintering and by equal channel angular
pressing (ECAP) with and without back pressure. The powder was
encapsulated in an aluminium can for consolidation through ECAP.
The properties obtained in the compacts by conventional sintering
route and by ECAP are compared. The effect of conventional
sintering and ECAP on consolidation behaviour of powder,
microstructure, density and hardness is discussed. Room temperature
back pressure aided ECAP results in nearly full denser (97% of its
theoretical density) compact at room temperature. NanoIndentation
technique was used to determine the modulus of the consolidated
compacts.
Abstract: In the current age, retrieval of relevant information
from massive amount of data is a challenging job. Over the years,
precise and relevant retrieval of information has attained high
significance. There is a growing need in the market to build systems,
which can retrieve multimedia information that precisely meets the
user's current needs. In this paper, we have introduced a framework
for refining query results before showing it to the user, using ambient
intelligence, user profile, group profile, user location, time, day, user
device type and extracted features. A prototypic tool was also
developed to demonstrate the efficiency of the proposed approach.
Abstract: The effect of Alumina nanoparticle size on thermophysical
properties, heat transfer performance and pressure loss characteristics of
Aviation Turbine Fuel (ATF)-Al2O3 nanofluids is studied experimentally for
the proposed application of regenerative cooling of semi-cryogenic rocket
engine thrust chambers. Al2O3 particles with mean diameters of 50 nm or 150
nm are dispersed in ATF. At 500C and 0.3% particle volume concentration,
the bigger particles show increases of 17% in thermal conductivity and 55% in
viscosity, whereas the smaller particles show corresponding increases of 21%
and 22% for thermal conductivity and viscosity respectively. Contrary to these
results, experiments to study the heat transfer performance and pressure loss
characteristics show that at the same pumping power, the maximum
enhancement in heat transfer coefficient at 500C and 0.3% concentration is
approximately 47% using bigger particles, whereas it is only 36% using
smaller particles.