Abstract: Transition prediction of boundary layers has always
been an important problem in fluid mechanics both theoretically and
practically, yet notwithstanding the great effort made by many
investigators, there is no satisfactory answer to this problem. The most
popular method available is so-called e-N method which is heavily
dependent on experiments and experience. The author has proposed
improvements to the e-N method, so to reduce its dependence on
experiments and experience to a certain extent. One of the key
assumptions is that transition would occur whenever the velocity
amplitude of disturbance reaches 1-2% of the free stream velocity.
However, the reliability of this assumption needs to be verified. In this
paper, transition prediction on a flat plate is investigated by using both
the improved e-N method and the parabolized stability equations (PSE)
methods. The results show that the transition locations predicted by
both methods agree reasonably well with each other, under the above
assumption. For the supersonic case, the critical velocity amplitude in
the improved e-N method should be taken as 0.013, whereas in the
subsonic case, it should be 0.018, both are within the range 1-2%.
Abstract: Green propellants used for satellite-level propulsion
system become attractive in recent years because the non-toxicity and
lower requirements of safety protection. One of the green propellants,
high-concentration hydrogen peroxide H2O2 solution (≥70% w/w,
weight concentration percentage), often known as high-test peroxide
(HTP), is considered because it is ITAR-free, easy to manufacture and
the operating temperature is lower than traditional monopropellant
propulsion. To establish satellite propulsion technology, the National
Space Organization (NSPO) in Taiwan has initialized a long-term
cooperation project with the National Cheng Kung University to
develop compatible tank and thruster. An experimental propulsion
payload has been allocated for the future self-reliant satellite to
perform orbit transfer and maintenance operations. In the present
research, an 1-Newton thruster prototype is designed and the thrusting
force is measured by a pendulum-type platform. The preliminary
hot-firing test at ambient environment showed the generated thrust and
the specific impulse are about 0.7 Newton and 102 seconds,
respectively.
Abstract: In this paper a new approach for transmission pricing
is presented. The main idea is voltage angle allocation, i.e.
determining the contribution of each contract on the voltage angle of
each bus. DC power flow is used to compute a primary solution for
angle decomposition. To consider the impacts of system non-linearity
on angle decomposition, the primary solution is corrected in different
iterations of decoupled Newton-Raphson power flow. Then, the
contribution of each contract on power flow of each transmission line
is computed based on angle decomposition. Contract-related flows
are used as a measure for “extent of use" of transmission network
capacity and consequently transmission pricing. The presented
approach is applied to a 4-bus test system and IEEE 30-bus test
system.
Abstract: Air bending is one of the important metal forming
processes, because of its simplicity and large field application.
Accuracy of analytical and empirical models reported for the analysis
of bending processes is governed by simplifying assumption and do
not consider the effect of dynamic parameters. Number of researches
is reported on the finite element analysis (FEA) of V-bending, Ubending,
and air V-bending processes. FEA of bending is found to be
very sensitive to many physical and numerical parameters. FE
models must be computationally efficient for practical use. Reported
work shows the 3D FEA of air bending process using Hyperform LSDYNA
and its comparison with, published 3D FEA results of air
bending in Ansys LS-DYNA and experimental results. Observing the
planer symmetry and based on the assumption of plane strain
condition, air bending problem was modeled in 2D with symmetric
boundary condition in width. Stress-strain results of 2D FEA were
compared with 3D FEA results and experiments. Simplification of
air bending problem from 3D to 2D resulted into tremendous
reduction in the solution time with only marginal effect on stressstrain
results. FE model simplification by studying the problem
symmetry is more efficient and practical approach for solution of
more complex large dimensions slow forming processes.
Abstract: Stirred tanks have applications in many chemical
processes where mixing is important for the overall performance of
the system. In present work 5%v of the tank is filled by solid particles
with diameter of 700 m that Rushton Turbine and Propeller impeller
is used for stirring. An Eulerian-Eulerian Multi Fluid Model coupled
and for modeling rotating of impeller, moving reference frame
(MRF) technique was used and standard-k- model was selected for
turbulency. Flow field, radial velocity and axial distribution of solid
for both of impellers was investigation and comparison. Comparisons
of simulation results between Rushton Turbine and propeller impeller
shows that final quality of solid-liquid slurry in different rotating
speed for propeller impeller is better than the Rushton Turbine.
Abstract: With the help of coincidence degree theory, sufficient
conditions for existence of periodic solutions for a food chain model
with functional responses on time scales are established.
Abstract: An experiment was conducted on the comparative
study of drip and furrow irrigation methods at the farmer-s field in
Umar Kot. The total area under experiment about 4000m2 was
divided into two equal portions. One portion about 40m X 50m was
occupied by drip and the other portion about 40m X 50m by furrow
irrigation method. Soil at the experimental site was clay loam in
texture for 0-60cm depth; average dry bulk density and field capacity
was 1.16g/cm3 and 28.5% respectively. The results reveal that the
drip irrigation method saved 56.4% water and gave 22% more yield
as compared to that of furrow irrigation method. Higher water use
efficiency about 4.87 was obtained in drip irrigation method; whereas
lower water used efficiency about 1.66 was obtained in furrow
irrigation method. The present study suggests farming community to
adopt drip irrigation method instead of old traditional flooding
methods.
Abstract: Teaching and learning about sustainability is a pedagogical endeavour with various innate difficulties and increased demands. Higher education has a dual role to play in addressing this challenge: to identify and explore innovative approaches and tools for addressing the complex and value-laden nature of sustainability in more meaningful ways, and to help teachers to integrate these approaches into their practice through appropriate professional development programs. The study reported here was designed and carried out within the context of a Masters course in Environmental Education. Eight teachers were collaboratively engaged in reconstructing a digital game microworld which was deliberately designed by the researchers to be questioned and evoke critical discussion on the idea of ‘sustainable city’. The study was based on the design-based research method. The findings indicate that the teachers’ involvement in processes of co-constructing the microworld initiated discussion and reflection upon the concepts of sustainability and sustainable lifestyles.
Abstract: Climate change is one of the greatest environmental,
economic, and social challenges of our time. Urban transportation has
had a major negative impact on our environment—most of our air
pollution comes from transport.
This paper explores ways to move toward a more sustainable
transport system by focusing on creating a more efficient and livable
city and improving the environmental efficiency of transport activity.
The analytical study covers some international examples of applying
sustainable transportation and uses them to suggest a frame work to
develop the transportation system in Egypt to be sustainable and more
intelligent.
Abstract: The objective of this work is to present a expertise on
flooding hazard analysis and how to reduce the risk. The analysis
concerns the disaster induced by the flood on November 10/11, 2001
in the Bab El Oued district of the city of Algiers.The study begins by
an expertise of damages in related with the urban environment and
the history of the urban growth of the site. After this phase, the work
is focalized on the identification of the existing correlations between
the development of the town and its vulnerability. The final step
consists to elaborate the interpretations on the interactions between
the urban growth, the sewerage network and the vulnerability of the
urban system.In conclusion, several recommendations are formulated
permitting the mitigation of the risk in the future. The principal
recommendations concern the new urban operations and the existing
urbanized sites.
Abstract: This paper evaluates the association between
economic environment in the districts of Madrid (Spain) and physical
inactivity, using income per capita as indicator of economic
environment. The analysis included 6,601 individuals aged 16 to 74
years. The measure of association estimated was the prevalence odds
ratio for physical inactivity by income per capita. After adjusting for
sex, age, and individual socioeconomic characteristics, people living
in the districts with the lowest per capita income had an odds ratio for
physical inactivity 1.58 times higher (95% confidence interval 1.35 to
1.85) than those living in districts with the highest per capita income.
Additional adjustment for the availability of sports facilities in each
district did not decrease the magnitude of the association. These
findings show that the widely believed assumption that the
availability of sports and recreational facilities, as a possible
explanation for the relation between economic environment and
physical inactivity, cannot be considered a universal observation.
Abstract: This paper considers the influence of promotion
instruments for renewable energy sources (RES) on a multi-energy
modeling framework. In Europe, so called Feed-in Tariffs are
successfully used as incentive structures to increase the amount of
energy produced by RES. Because of the stochastic nature of large
scale integration of distributed generation, many problems have
occurred regarding the quality and stability of supply. Hence, a
macroscopic model was developed in order to optimize the power
supply of the local energy infrastructure, which includes electricity,
natural gas, fuel oil and district heating as energy carriers. Unique
features of the model are the integration of RES and the adoption of
Feed-in Tariffs into one optimization stage. Sensitivity studies are
carried out to examine the system behavior under changing profits
for the feed-in of RES. With a setup of three energy exchanging
regions and a multi-period optimization, the impact of costs and
profits are determined.
Abstract: The linear methods of heart rate variability analysis
such as non-parametric (e.g. fast Fourier transform analysis) and
parametric methods (e.g. autoregressive modeling) has become an
established non-invasive tool for marking the cardiac health, but their
sensitivity and specificity were found to be lower than expected with
positive predictive value
Abstract: Behavior of turbulent jet is relying on jet parameters,
environmental and geometric parameters. In this research, it has
attempt to Study effect of jet parameters of internal angle on
maximum effective length and velocity on centerline from nozzle
experimentally. Toward this end, four internal angles 30, 45, 60 and
90-degree are considered for this study in a flume with 600cm as
long, 100cm as high and 150cm in width. Various discharges were
used to evaluate effective length for a wide range of densimetric
Froude numbers F0, from 17.9 to 39.4 that is defined at the nozzle. As
a result, It is revealed that both velocity on centerline and effective
length decreases when nozzle angle decreased from 90° to 30°. The
results show that, for all range of Fr0 the Um/U0 ratio for nozzle with
α=90° on centerline increases 20% - 27% than nozzle with α=30° that
has lowest velocity on centerline than other nozzle.
Abstract: The solvated electron is self-trapped (polaron) owing
to strong interaction with the quantum polarization field. If the
electron and quantum field are strongly coupled then the collective
localized state of the field and quasi-particle is formed. In such a
formation the electron motion is rather intricate. On the one hand the
electron oscillated within a rather deep polarization potential well
and undergoes the optical transitions, and on the other, it moves
together with the center of inertia of the system and participates in
the thermal random walk. The problem is to separate these motions
correctly, rigorously taking into account the conservation laws. This
can be conveniently done using Bogolyubov-Tyablikov method of
canonical transformation to the collective coordinates. This
transformation removes the translational degeneracy and allows one
to develop the successive approximation algorithm for the energy and
wave function while simultaneously fulfilling the law of conservation
of total momentum of the system. The resulting equations determine
the electron transitions and depend explicitly on the translational
velocity of the quasi-particle as whole. The frequency of optical
transition is calculated for the solvated electron in ammonia, and an
estimate is made for the thermal-induced spectral bandwidth.
Abstract: Abstraction of water from the dry river sand-beds is
well-known as an alternative source of water during dry seasons.
Internally, because of the form of sand particles, voids are created
which can store water in the riverbeds. Large rivers are rare in South
Africa. Many rivers are sand river types and without water during the
prolonged dry periods. South Africa has not taken full advantage of
water storage in sand as a solution to the growing water scarcity both
in urban and rural areas. The paper reviews the benefits of run-off
storage in sand reservoirs gained from other arid areas and need for
adoption in rural areas of South Africa as an alternative water supply
where it is probable.
Abstract: In many data mining applications, it is a priori known
that the target function should satisfy certain constraints imposed
by, for example, economic theory or a human-decision maker. In this
paper we consider partially monotone prediction problems, where the
target variable depends monotonically on some of the input variables
but not on all. We propose a novel method to construct prediction
models, where monotone dependences with respect to some of
the input variables are preserved by virtue of construction. Our
method belongs to the class of mixture models. The basic idea is to
convolute monotone neural networks with weight (kernel) functions
to make predictions. By using simulation and real case studies,
we demonstrate the application of our method. To obtain sound
assessment for the performance of our approach, we use standard
neural networks with weight decay and partially monotone linear
models as benchmark methods for comparison. The results show that
our approach outperforms partially monotone linear models in terms
of accuracy. Furthermore, the incorporation of partial monotonicity
constraints not only leads to models that are in accordance with the
decision maker's expertise, but also reduces considerably the model
variance in comparison to standard neural networks with weight
decay.
Abstract: Biological treatment of secondary effluent wastewater
by two combined denitrification/oxic filtration systems packed with
Lock type(denitrification filter) and ceramic ball (oxic filter) has been
studied for 5months. Two phases of operating conditions were carried
out with an influent nitrate and ammonia concentrations varied from
5.8 to 11.7mg/L and 5.4 to 12.4mg/L,respectively.
Denitrification/oxic filter treatment system were operated under an
EBCT (Empty Bed Contact Time) of 4h at system recirculation ratio in
the range from 0 to 300% (Linear Velocity increased 19.5m/d to
78m/d). The system efficiency of denitrification , nitrification over
95% respectively. Total nitrogen and COD removal range from
54.6%(recirculation 0%) to 92.3%(recirculation 300%) and 10% to
62.5%, respectively.
Abstract: Image processing for capsule endoscopy requires large
memory and it takes hours for diagnosis since operation time is
normally more than 8 hours. A real-time analysis algorithm of capsule
images can be clinically very useful. It can differentiate abnormal
tissue from health structure and provide with correlation information
among the images. Bleeding is our interest in this regard and we
propose a method of detecting frames with potential bleeding in
real-time. Our detection algorithm is based on statistical analysis and
the shapes of bleeding spots. We tested our algorithm with 30 cases of
capsule endoscopy in the digestive track. Results were excellent where
a sensitivity of 99% and a specificity of 97% were achieved in
detecting the image frames with bleeding spots.
Abstract: In this paper, growth and collapse of a vapour bubble
generated due to a local energy input inside a rigid cylinder and in
the absence of buoyancy forces is investigated using Boundary
Integral Equation Method and Finite Difference Method .The fluid is
treated as potential flow and Boundary Integral Equation Method is
used to solve Laplace-s equation for velocity potential. Different
ratios of the diameter of the rigid cylinder to the maximum radius of
the bubble are considered. Results show that during the collapse
phase of the bubble inside a vertical rigid cylinder, two liquid micro
jets are developed on the top and bottom sides of the vapour bubble
and are directed inward. It is found that by increasing the ratio of the
cylinder diameter to the maximum radius of the bubble, the rate of
the growth and collapse phases of the bubble increases and the life
time of the bubble decreases.