Abstract: A three-dimensional numerical simulation of flow
through mini and microchannels with designed roughness is
conducted here. The effect of the roughness height (surface
roughness), geometry, Reynolds number on the friction factor, and
Nusselt number is investigated. The study is carried out by
employing CFD software, CFX. Our work focuses on a water flow
inside a circular mini-channel of 1 mm and microchannels of 500 and
100 m in diameter. The speed entry varies from 0.1 m/s to 20 m/s.
The general trend can be observed that bigger sizes of roughness
element lead to higher flow resistance. It is found that the friction
factor increases in a nonlinear fashion with the increase in obstruction
height. Particularly, the effect of roughness can no longer be ignored
at relative roughness height higher than 3%. A significant increase in
Poiseuille number is detected for all configurations considered. The
same observation can be done for Nusselt number. The transition
zone between laminar and turbulent flow depends on the channel
diameter.
Abstract: The transesterification of dimethyl malonate (DMM)
with phenol has been studied in vapour phase over cordierite
honeycomb coated with solid acid catalysts such as ZrO2,
Mo(VI)/ZrO2 and SO42-/ZrO2. The catalytic materials were prepared
honeycomb coated, powder forms, and characterized for their total
surface acidity by NH3-TPD and crystalinity by powder XRD
methods. Phenyl methyl malonate (PMM) and diphenyl malonate
(DPM) were obtained as the reaction products. A good conversion of
DMM (up to 82%) of MPM with 95% selectivity was observed when
the reactions were carried out at a catalyst bed temperature of 200 °C
and flow-rate of 10 mL/h in presence of Mo(VI)/ZrO2 as catalyst.
However, over SO4^2-/ZrO2 catalyst, the yield of DPM was found to be
higher. The results have been interpreted based on the variation of
acidic properties and powder XRD phases of zirconia on
incorporation of Mo(VI) or SO42– ions. Transesterification reactions
were also carried out over powder forms of the catalytic materials
and the yield of the desired phenyl ester products were compared
with that of the HC coated catalytic materials. The solid acids were
found to be reusable when used for at least 5 reaction cycles.
Abstract: In the vicinity of red sea about 15 fungi species were
isolated from oil contaminated sites. On the basis of aptitude to
degrade the crude oil and DCPIP assay, two fungal isolates were
selected amongst 15 oil degrading strains. Analysis of ITS-1, ITS-2
and amplicon pyrosequencing studies of fungal diversity revealed
that these strains belong to Penicillium and Aspergillus species. Two
strains that proved to be the most efficient in degrading crude oil was
Aspergillus niger (54%) and Penicillium commune (48%) Subsequent
to two weeks of cultivation in BHS medium the degradation rate
were recorded by using spectrophotometer and GC-MS. Hence, it is
cleared that these fungal strains has capability of degradation and can
be utilize for cleaning the Saudi Arabian environment.
Abstract: Anogeissus leiocarpus (Combretaceae) is well known
for its medicinal uses in African traditional medicine, for treating
many human diseases mainly skin diseases and infections. Mycetoma
disease is a fungal and/ or bacterial skininfection, mainly cause by
Madurella mycetomatis fungus. This study was carried out in vitro to
investigate the antifungal activity of Anogeissus leiocarpus leaf
extracts against the isolated pathogenic Madurella mycetomatis, by
using the NCCLS modified method compared to Ketoconazole
standard drug, and MTT assay. The bioactive fraction was subjected
to chemical analysis implementing different chromatographic
analytical methods (TLC, HPLC, and LC-MS/MS). The results
showed significance antifungal activity of A. leiocarpus leaf extracts
against the isolated pathogenic M. mycetomatis, compared to negative
and positive controls. The chloroform fraction showed the highest
antifungal activity. The chromatographic analysis of the chloroform
fraction with the highest activity showed the presence of important
bioactive compounds such as ellagic and flavellagic acids derivatives,
flavonoids and stilbenoid, which are well known for their antifungal
activity.
Abstract: A field experiment was conducted in the Agricultural
Research Station, at El-Ghoraieb, Assiut to study dry seed yield
performance of two locally adapted cultivars (‘Azmerly’ and ‘Cream
7’) and two line introductions (IT81D-1032 and IT82D-812) of
common cowpea (Vigna unguiculata (L.) Walp) grown at three
different within-row spaces (20, 30 and 40 cm) and two planting
dates in the summer (April 15th and 30th) and in the fall season (Aug.
12th and 27th) of two successive seasons. The data showed that total
dry-seed yield produced by plants grown at 20 cm was greater than at
30 cm in all cvs/lines in both years. Increases in 1000-seed weight
were detected in cv ‘Azmerly’ and line IT82D-812 when they were
grown at 30 cm as compared with 20 cm in the summer season.
However, in the fall season such increases were found in all cvs/lines.
Planting at 40 cm produced seeds of greater weight than planting at
30 cm for all cvs/lines in the fall season and also in cv. Cream 7 and
line IT82D-812 in the summer season, while all cvs/lines in the fall
Planting on April 15th in the summer and also planting on Aug. 12th
in the fall had plants which showed increases in 1000-seed weight
and total dry-seed yield. The greatest 1000-seed weight was found in
the line IT81D-1032 in the summer season and in the line IT82D-812
in the fall season. The sum up results revealed that ‘Azmerly’
produced greater dry-seed yield than ‘Cream 7’ and both of them
were superior to the line IT82D-812 and IT81D-1032 in the summer
season. In the fall, however, the line IT82D-812 produced greater
dry-seed yield than the other cultivars/lines.
Abstract: The customers use the best compromise criterion
between price and quality of service (QoS) to select or change
their Service Provider (SP). The SPs share the same market and
are competing to attract more customers to gain more profit. Due
to the divergence of SPs interests, we believe that this situation is a
non-cooperative game of price and QoS. The game converges to an
equilibrium position known Nash Equilibrium (NE). In this work, we
formulate a game theoretic framework for the dynamical behaviors
of SPs. We use Genetic Algorithms (GAs) to find the price and
QoS strategies that maximize the profit for each SP and illustrate
the corresponding strategy in NE. In order to quantify how this NE
point is performant, we perform a detailed analysis of the price of
anarchy induced by the NE solution. Finally, we provide an extensive
numerical study to point out the importance of considering price and
QoS as a joint decision parameter.
Abstract: Foundation differential settlement and supported
structure tilting are an occasionally occurred engineering problem.
This may be caused by overloading, changes in ground soil properties
or unsupported nearby excavations. Engineering thinking points
directly toward the logic solution for such problem by uplifting the
settled side. This can be achieved with deep foundation elements
such as micro-piles and macro-piles™, jacked piers, and helical piers,
jet grouted mortar columns, compaction grout columns, cement
grouting or with chemical grouting, or traditional pit underpinning
with concrete and mortar. Although, some of these techniques offer
economic, fast and low noise solutions, many of them are quite the
contrary. For tilted structures, with the limited inclination, it may be much
easier to cause a balancing settlement on the less-settlement side
which shall be done carefully in a proper rate. This principal has been
applied in Leaning Tower of Pisa stabilization with soil extraction
from the ground surface. In this research, the authors attempt to
introduce a new solution with a different point of view. So, the
micro-tunneling technique is presented in here as an intended ground
deformation cause. In general, micro-tunneling is expected to induce
limited ground deformations. Thus, the researchers propose to apply
the technique to form small size ground unsupported holes to produce
the target deformations. This shall be done in four phases: 1.
Application of one or more micro-tunnels, regarding the existing
differential settlement value, under the raised side of the tilted
structure. 2. For each individual tunnel, the lining shall be pulled out
from both sides (from jacking and receiving shafts) in the slow rate.
3. If required, according to calculations and site records, an additional
surface load can be applied on the raised foundation side. 4. Finally, a
strengthening soil grouting shall be applied for stabilization after
adjustment. A finite element based numerical model is presented to simulate
the proposed construction phases for different tunneling positions and
tunnels group. For each case, the surface settlements are calculated
and induced plasticity points are checked. These results show the
impact of the suggested procedure on the tilted structure and its
feasibility. Comparing results also show the importance of the
position selection and tunnels group gradual effect. Thus, a new
engineering solution is presented to one of the structural and
geotechnical engineering challenges.
Abstract: Radio Frequency Identification (RFID) has become a
key technology in the emerging concept of Internet of Things (IoT).
Naturally, business applications would require the deployment of
various RFID systems developed by different vendors that use
different data formats and structures. This heterogeneity poses a
challenge in developing real-life IoT systems with RFID, as
integration is becoming very complex and challenging. Semantic
integration is a key approach to deal with this challenge. To do so,
ontology for RFID systems need to be developed in order to
annotated semantically RFID systems, and hence, facilitate their
integration. Accordingly, in this paper, we propose ontology for
RFID systems. The proposed ontology can be used to semantically
enrich RFID systems, and hence, improve their usage and reasoning.
Abstract: Many herbal medicinal products are considered
potential anti-hypercholesterolemic agents with encouraging safety
profiles, however only a limited amount of clinical research exists to
support their efficacy. The present study was designed to compare the
antihypercholesterolemic and antioxidant activities of the crude
ethanolic extracts of Citrus reticulata fruit peel, Zingiber officinale
rhizome and Sesamum indicum seeds. Forty-five rats were used throughout the experiment which are
extended for four weeks. These were divided into nine groups, five
rats per each group as follows; group 1 was the normal control group
(rats only fed standard normal rat diet), group 2 was the
hypercholesterolemic control group (rats fed only
hypercholesterolemic diet which contained 1% cholesterol plus 10%
saturated animal fat added to the normal rat diet), groups 3 and 4
were fed hypercholesterolemic diet in addition to Citrus reticulata
ethanolic extract at doses of (250mg/kg (group 3) and 500mg/kg
(group 4)) administered daily via oral route, groups 5 and 6 were
given hypercholesterolemic diet in addition to Zingiber officinale
ethanolic extract at doses of (250mg/kg (group 5) and 500mg/kg
(group 6)) daily through oral route, groups 7 and 8 fed on
hypercholesterolemic diet in addition to Sesamum indicum ethanolic
extract at doses of (250mg/kg (group 7) and 500mg/kg (group 8))
daily orally; and group 9 rats were given hypercholesterolemic diet in
addition to atorvastatin (0.18mg/kg) daily via oral route as a standard
reference antihypercholesterolemic drug. Blood samples from all
groups were drawn from the retro-orbital venous plexus four weeks
following treatment after overnight fasting and the lipid profile (total
cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low
density lipoprotein-cholesterol (LDL-C) and triglyceride levels) were
measured and the risk ratio (TC/HDL-C) was assessed. The
antioxidant activity of the three plants extracts was determined using
DPPH free-radical antioxidant assay. Results of in vivo and in vitro
antihypercholesterolemic and antioxidant assay respectively, revealed
that the three extracts possess comparable antioxidant and
antihypercholesterolemic activities.
Abstract: In this study, we investigated numerically heat
transfer by mixed convection coupled to radiation in a square cavity;
the upper horizontal wall is movable. The purpose of this study is to
see the influence of the emissivity ε and the varying of the
Richardson number Ri on the variation of average Nusselt number
Nu. The vertical walls of the cavity are differentially heated, the left
wall is maintained at a uniform temperature higher than the right
wall, and the two horizontal walls are adiabatic. The finite volume
method is used for solving the dimensionless Governing Equations.
Emissivity values used in this study are ranged between 0 and 1, the
Richardson number in the range 0.1 to 10. The Rayleigh number is
fixed to Ra=104 and the Prandtl number is maintained constant
Pr=0.71. Streamlines, isothermal lines and the average Nusselt
number are presented according to the surface emissivity. The results
of this study show that the Richardson number Ri and emissivity ε
affect the average Nusselt number.
Abstract: In this paper, we present an application of Riemannian
geometry for processing non-Euclidean image data. We consider the
image as residing in a Riemannian manifold, for developing a new
method to brain edge detection and brain extraction. Automating this
process is a challenge due to the high diversity in appearance brain
tissue, among different patients and sequences. The main contribution, in this paper, is the use of an edge-based
anisotropic diffusion tensor for the segmentation task by integrating
both image edge geometry and Riemannian manifold (geodesic,
metric tensor) to regularize the convergence contour and extract
complex anatomical structures. We check the accuracy of the
segmentation results on simulated brain MRI scans of single
T1-weighted, T2-weighted and Proton Density sequences. We
validate our approach using two different databases: BrainWeb
database, and MRI Multiple sclerosis Database (MRI MS DB). We
have compared, qualitatively and quantitatively, our approach with
the well-known brain extraction algorithms. We show that using
a Riemannian manifolds to medical image analysis improves the
efficient results to brain extraction, in real time, outperforming the
results of the standard techniques.
Abstract: In this study, students’ learning has been investigated
and satisfaction in one of the course offered at Qatar University
Foundation Program. Innovative teaching has been implied
methodology that emphasizes on enhancing students’ thinking skills,
decision making, and problem solving skills. Some interesting results
were found which could be used to further improvement of the
teaching methodology. In Fall 2012 in Foundation Program Math
department at Qatar University has started implementing new ways
of teaching Math by introducing MyMathLab (MML) as an
innovative interactive tool in addition of the use Blackboard to
support standard teaching such as Discussion board in Virtual class to
engage students outside of classroom and to enhance independent,
active learning that promote students’ critical thinking skills, decision
making, and problem solving skills through the learning process.
Abstract: Carbon nanotubes (CNTs) are known for having high elastic properties with high surface area that promote them as good candidates for reinforcing polymeric matrices. In composite materials, CNTs lack chemical bonding with the surrounding matrix which decreases the possibility of better stress transfer between the components. In this work, a chemical treatment for activating the surface of the multi-wall carbon nanotubes (MWCNT) was applied and the effect of this functionalization on the elastic properties of the epoxy nanocomposites was studied. Functional amino-groups were added to the surface of the CNTs and it was evaluated to be about 34% of the total weight of the CNTs. Elastic modulus was found to increase by about 40% of the neat epoxy resin at CNTs’ weight fraction of 0.5%. The elastic modulus was found to decrease after reaching a certain concentration of CNTs which was found to be 1% wt. The scanning electron microscopic pictures showed the effect of the CNTs on the crack propagation through the sample by forming stress concentrated spots at the nanocomposite samples.
Abstract: Thermal enhancement of a single mini channel in
Proton Exchange Membrane Fuel Cell (PEMFC) cooling plate is
numerically investigated. In this study, low concentration of Al2O3 in
Water - Ethylene Glycol mixtures is used as coolant in single channel
of carbon graphite plate to mimic the mini channels in PEMFC
cooling plate. A steady and incompressible flow with constant heat
flux is assumed in the channel of 1mm x 5mm x 100mm. Nano
particle of Al2O3 used ranges from 0.1, 0.3 and 0.5 vol %
concentration and then dispersed in 60:40 (water: Ethylene Glycol)
mixture. The effect of different flow rates to fluid flow and heat
transfer enhancement in Re number range of 20 to 140 was observed.
The result showed that heat transfer coefficient was improved by
18.11%, 9.86% and 5.37% for 0.5, 0.3 and 0.1 vol. % Al2O3 in 60:40
(water: EG) as compared to base fluid of 60:40 (water: EG). It is also
showed that the higher vol. % concentration of Al2O3 performed
better in term of thermal enhancement but at the expense of higher
pumping power required due to increase in pressure drop
experienced. Maximum additional pumping power of 0.0012W was
required for 0.5 vol % Al2O3 in 60:40 (water: EG) at Re number 140.
Abstract: In this numerical work, mixed convection and entropy
generation of Cu–water nanofluid in a lid-driven square cavity have
been investigated numerically using the Lattice Boltzmann Method.
Horizontal walls of the cavity are adiabatic and vertical walls have
constant temperature but different values. The top wall has been
considered as moving from left to right at a constant speed, U0. The
effects of different parameters such as nanoparticle volume
concentration (0–0.05), Rayleigh number (104–106) and Reynolds
numbers (1, 10 and 100) on the entropy generation, flow and
temperature fields are studied. The results have shown that addition
of nanoparticles to the base fluid affects the entropy generation, flow
pattern and thermal behavior especially at higher Rayleigh and low
Reynolds numbers. For pure fluid as well as nanofluid, the increase
of Reynolds number increases the average Nusselt number and the
total entropy generation, linearly. The maximum entropy generation
occurs in nanofluid at low Rayleigh number and at high Reynolds
number. The minimum entropy generation occurs in pure fluid at low
Rayleigh and Reynolds numbers. Also at higher Reynolds number,
the effect of Cu nanoparticles on enhancement of heat transfer was
decreased because the effect of lid-driven cavity was increased. The
present results are validated by favorable comparisons with
previously published results. The results of the problem are presented
in graphical and tabular forms and discussed.
Abstract: There are real needs to integrate types of Open
Educational Resources (OER) with an intelligent system to extract
information and knowledge in the semantic searching level. The
needs came because most of current learning standard adopted web
based learning and the e-learning systems do not always serve all
educational goals. Semantic Web systems provide educators,
students, and researchers with intelligent queries based on a semantic
knowledge management learning system. An ontology-based learning
system is an advanced system, where ontology plays the core of the
semantic web in a smart learning environment. The objective of this
paper is to discuss the potentials of ontologies and mapping different
kinds of ontologies; heterogeneous or homogenous to manage and
control different types of Open Educational Resources. The important
contribution of this research is that it uses logical rules and
conceptual relations to map between ontologies of different
educational resources. We expect from this methodology to establish
an intelligent educational system supporting student tutoring, self and
lifelong learning system.
Abstract: Social Avoidance is one of the most important
problems that face a good number of disabled students. It results from
the negative attitudes of non-disabled students, teachers and others.
Some of the past research has shown that non-disabled individuals
hold negative attitudes toward persons with disabilities. The present
study aims to alleviate Social Avoidance by applying the Cognitive
Behavioral Intervention. 24 Blind students aged 19–24 (university students) were randomly
chosen we compared an experimental group (consisted of 12
students) who went through the intervention program, with a control
group (12 students also) who did not go through such intervention.
We used the Social Avoidance and Distress Scale (SADS) to assess
social anxiety and distress behavior. The author used many
techniques of cognitive behavioral intervention such as modeling,
cognitive restructuring, extension, contingency contracts, selfmonitoring,
assertiveness training, role play, encouragement and
others. Statistically, T-test was employed to test the research
hypothesis. Result showed that there is a significance difference between the
experimental group and the control group after the intervention and
also at the follow up stages of the Social Avoidance and Distress
Scale. Also for the experimental group, there is a significance
difference before the intervention and the follow up stages for the
scale. Results showed that, there is a decrease in social avoidance.
Accordingly, cognitive behavioral intervention program was
successful in decreasing social avoidance for blind students.
Abstract: Due to the interference effects, the intrinsic
aerodynamic parameters obtained from the individual component
testing are always fundamentally different than those obtained for
complete model testing. Consideration and limitation for such testing
need to be taken into account in any design work related to the
component buildup method. In this paper, the scaled model of a
straight rectangular canard of a hybrid buoyant aircraft is tested at 50
m/s in IIUM-LSWT (Low Speed Wind Tunnel). Model and its
attachment with the balance are kept rigid to have results free from
the aeroelastic distortion. Based on the velocity profile of the test
section’s floor; the height of the model is kept equal to the
corresponding boundary layer displacement. Balance measurements
provide valuable but limited information of overall aerodynamic
behavior of the model. Zero lift coefficient is obtained at -2.2o and
the corresponding drag coefficient was found to be less than that at
zero angle of attack. As a part of the validation of low fidelity tool,
plot of lift coefficient plot was verified by the experimental data and
except the value of zero lift coefficients, the overall trend has under
predicted the lift coefficient. Based on this comparative study, a
correction factor of 1.36 is proposed for lift curve slope obtained
from the panel method.
Abstract: For a rigid body sliding on a rough surface, a range of
uncertainty or non-uniqueness of solution could be found, which is
termed: Painlevé paradox. Painlevé paradox is the reason of a wide
range of bouncing motion, observed during sliding of robotic
manipulators on rough surfaces. In this research work, the existence
of the paradox zone during the sliding motion of a two-link (P-R)
robotic manipulator with a unilateral constraint is investigated.
Parametric study is performed to investigate the effect of friction,
link-length ratio, total height and link-mass ratio on the paradox zone.
Abstract: This paper discusses the general methods to saturation
in the steady-state, two axis (d & q) frame models of synchronous
machines. In particular, the important role of the magnetic coupling
between the d-q axes (cross-magnetizing phenomenon), is
demonstrated. For that purpose, distinct methods of saturation
modeling of dumper synchronous machine with cross-saturation are
identified, and detailed models synthesis in d-q axes. A number of
models are given in the final developed form. The procedure and the
novel models are verified by a critical application to prove the
validity of the method and the equivalence between all developed
models is reported. Advantages of some of the models over the
existing ones and their applicability are discussed.