Abstract: The change in orbit evolution between collocated
satellites (X, Y) inside +/-0.09° E/W and +/- 0.07° N/S cluster, after
one of these satellites is placed in an inclined orbit (satellite X) and
the effect of this change in the collocation safety inside the cluster
window has been studied and evaluated. Several collocation scenarios had been studied in order to adjust
the location of both satellites inside their cluster to maximize the
separation between them and safe the mission.
Abstract: This paper presents numerical analysis in terms of
buckling resistance of GFRP sandwich infill panels system under the
influence of increased temperature on the foam core. Failure mode
under in-plane compression is studied by means of numerical analysis
with ABAQUS platform. Parameters considered in this study are
contact length and both the type of foam for core and the variation of
its module elastic under the thermal influence. Increment of
temperature is considered in static cases and only applied to core.
Indeed, it is proven that the effect of temperature alters the mechanical
properties of the entire panel system. Moreover, the rises of
temperature result in a decrease in strength of the panel. This is due to
the polymeric nature of this material. Additionally, the contact length
also displays the effect on performance of infill panel. Their
significance factors are based on type of polymer for core. Therefore,
by comparing difference type of core material, the variation can be
reducing.
Abstract: Since the advances in digital imaging technologies have led to
development of high quality digital devices, there are a lot of illegal copies
of copyrighted video content on the Internet. Also, unauthorized editing is
occurred frequently. Thus, we propose an editing prevention technique for
high-quality (HQ) video that can prevent these illegally edited copies from
spreading out. The proposed technique is applied spatial and temporal gradient
methods to improve the fidelity and detection performance. Also, the scheme
duplicates the embedding signal temporally to alleviate the signal reduction
caused by geometric and signal-processing distortions. Experimental results
show that the proposed scheme achieves better performance than previously
proposed schemes and it has high fidelity. The proposed scheme can be used
in unauthorized access prevention method of visual communication or traitor
tracking applications which need fast detection process to prevent illegally
edited video content from spreading out.
Abstract: When evaluating the capacity of a generation park to
cover the load in transmission systems, traditional Loss of Load
Expectation (LOLE) and Expected Energy not Served (EENS)
indices can be used. If those indices allow computing the annual
duration and severity of load non covering situations, they do not take
into account the fact that the load excess is generally shifted from one
penury state (hour or quarter of an hour) to the following one. In this
paper, a sequential Monte Carlo framework is introduced in order to
compute adjusted LOLE and EENS indices. Practically, those
adapted indices permit to consider the effect of load excess transfer
on the global adequacy of a generation park, providing thus a more
accurate evaluation of this quantity.
Abstract: Lead being a toxic heavy metal that mankind is
exposed to the highest levels of this metal. There are different sources
of environmental pollution with lead as lead alkyl additives in petrol
and manufacturing processes. The contaminated atmosphere in urban
and industrial areas by lead in Egypt may lead to the contamination
of foods beside the other different sources. The present investigation
studied the risk assessment of lead in some Egyptian edible
vegetables and fruits collected from different environments in Greater
Cairo Governorate, i.e. industrial, heavy traffic and rural areas. A
total of 325 leafy and fruity vegetables and fruits samples belonging
to 11, 6 and 4 different species, respectively were randomly collected
from markets of the three main models. Data indicated the variation
of lead levels in different three areas. The highest levels of lead were
detected in the samples collected from industrial and traffic areas.
However, the lowest levels were found in the rural areas. It could be
concluded that determination of lead levels in foods from different
localities and environments at regularly is very important.
Abstract: As one of the convenient and noninvasive sensing
approaches, the automatic limb girth measurement has been applied
to detect intention behind human motion from muscle deformation.
The sensing validity has been elaborated by preliminary researches
but still need more fundamental studies, especially on kinetic
contraction modes. Based on the novel fabric strain sensors, a soft
and smart limb girth measurement system was developed by the
authors’ group, which can measure the limb girth in-motion.
Experiments were carried out on elbow isometric flexion and elbow
isokinetic flexion (biceps’ isokinetic contractions) of 90°/s, 60°/s, and
120°/s for 10 subjects (2 canoeists and 8 ordinary people). After
removal of natural circumferential increments due to elbow position,
the joint torque is found not uniformly sensitive to the limb
circumferential strains, but declining as elbow joint angle rises,
regardless of the angular speed. Moreover, the maximum joint torque
was found as an exponential function of the joint’s angular speed.
This research highly contributes to the application of the automatic
limb girth measuring during kinetic contractions, and it is useful to
predict the contraction level of voluntary skeletal muscles.
Abstract: Inspired by the Formula-1 competition, IMechE
(Institute of Mechanical Engineers) and Formula SAE (Society of
Mechanical Engineers) organize annual competitions for University
and College students worldwide to compete with a single-seat racecar
they have designed and built. Design of the chassis or the frame is a
key component of the competition because the weight and stiffness
properties are directly related with the performance of the car and the
safety of the driver. In addition, a reduced weight of the chassis has
direct influence on the design of other components in the car. Among
others, it improves the power to weight ratio and the aerodynamic
performance. As the power output of the engine or the battery
installed in the car is limited to 80 kW, increasing the power to
weight ratio demands reduction of the weight of the chassis, which
represents the major part of the weight of the car. In order to reduce
the weight of the car, ION Racing team from University of
Stavanger, Norway, opted for a monocoque design. To ensure
fulfilment of the competition requirements of the chassis, the
monocoque design should provide sufficient torsional stiffness and
absorb the impact energy in case of possible collision. The study reported in this article is based on the requirements for
Formula Student competition. As part of this study, diverse
mechanical tests were conducted to determine the mechanical
properties and performances of the monocoque design. Upon a
comprehensive theoretical study of the mechanical properties of
sandwich composite materials and the requirements of monocoque
design in the competition rules, diverse tests were conducted
including 3-point bending test, perimeter shear test and test for
absorbed energy. The test panels were homemade and prepared with
equivalent size of the side impact zone of the monocoque, i.e. 275
mm x 500 mm, so that the obtained results from the tests can be
representative. Different layups of the test panels with identical core
material and the same number of layers of carbon fibre were tested
and compared. Influence of the core material thickness was also
studied. Furthermore, analytical calculations and numerical analysis
were conducted to check compliance to the stated rules for Structural
Equivalency with steel grade SAE/AISI 1010. The test results were
also compared with calculated results with respect to bending and
torsional stiffness, energy absorption, buckling, etc. The obtained results demonstrate that the material composition
and strength of the composite material selected for the monocoque
design has equivalent structural properties as a welded frame and thus
comply with the competition requirements. The developed analytical
calculation algorithms and relations will be useful for future
monocoque designs with different lay-ups and compositions.
Abstract: Geopolymer composites reinforced with flax fabrics
and nanoclay are fabricated and studied for physical and mechanical
properties using X-Ray Diffraction (XRD), Fourier Transform
Infrared Spectroscopy (FTIR), and Scanning Electron Microscope
(SEM). Nanoclay platelets at a weight of 1.0%, 2.0%, and 3.0% were
added to geopolymer pastes. Nanoclay at 2.0 wt.% was found to
improve density and decrease porosity while improving flexural
strength and post-peak toughness. A microstructural analysis
indicated that nanoclay behaves as filler and as an activator
supporting geopolymeric reaction while producing a higher content
geopolymer gel improving the microstructure of binders. The process
enhances adhesion between the geopolymer matrix and flax fibres.
Abstract: Both steady and unsteady turbulent mixed convection
heat transfer in a 3D lid-driven enclosure, which has constant heat
flux on the middle of bottom wall and with isothermal moving
sidewalls, is reported in this paper for working fluid with Prandtl
number Pr = 0.71. The other walls are adiabatic and stationary. The
dimensionless parameters used in this research are Reynolds number,
Re = 5000, 10000 and 15000, and Richardson number, Ri = 1 and 10.
The simulations have been done by using different turbulent methods
such as RANS, URANS, and LES. The effects of using different k-ε
models such as standard, RNG and Realizable k-ε model are
investigated. Interesting behaviours of the thermal and flow fields
with changing the Re or Ri numbers are observed. Isotherm and
turbulent kinetic energy distributions and variation of local Nusselt
number at the hot bottom wall are studied as well. The local Nusselt
number is found increasing with increasing either Re or Ri number.
In addition, the turbulent kinetic energy is discernibly affected by
increasing Re number. Moreover, the LES results have shown good
ability of this method in predicting more detailed flow structures in
the cavity.
Abstract: Response Surface Methods (RSM) provide
statistically validated predictive models that can then be manipulated
for finding optimal process configurations. Variation transmitted to
responses from poorly controlled process factors can be accounted
for by the mathematical technique of propagation of error (POE),
which facilitates ‘finding the flats’ on the surfaces generated by
RSM. The dual response approach to RSM captures the standard
deviation of the output as well as the average. It accounts for
unknown sources of variation. Dual response plus propagation of
error (POE) provides a more useful model of overall response
variation. In our case, we implemented this technique in predicting
compressive strength of concrete of 28 days in age. Since 28 days is
quite time consuming, while it is important to ensure the quality
control process. This paper investigates the potential of using design
of experiments (DOE-RSM) to predict the compressive strength of
concrete at 28th day. Data used for this study was carried out from
experiment schemes at university of Benghazi, civil engineering
department. A total of 114 sets of data were implemented. ACI mix
design method was utilized for the mix design. No admixtures were
used, only the main concrete mix constituents such as cement, coarseaggregate,
fine aggregate and water were utilized in all mixes.
Different mix proportions of the ingredients and different water
cement ratio were used. The proposed mathematical models are
capable of predicting the required concrete compressive strength of
concrete from early ages.
Abstract: This study evaluated the acute toxicity and tissue
distribution of intravenously administered gold nanoparticles
(AuNPs) in male rabbits. Rabbits were exposed to single dose of
AuNPs (300 μg/ kg). Toxic effects were assessed via general
behavior, hematological parameters, serum biochemical parameters,
and histopathological examination of various rabbits’ organs.
Inductively coupled plasma–mass spectrometry (ICP-MS) was used
to determine gold concentrations in tissue samples collected at
predetermined time intervals. After one week, AuNPs exerted no
obvious acute toxicity in rabbits. However, inflammatory reactions
were observed in liver, lungs and kidneys accompanied with mild
absolute neutrophilia and significant monocytosis. The highest gold
levels were found in the spleen and liver followed by lungs, and
kidneys. These results indicated that AuNPs could be distributed
extensively to various tissues in the body, but primarily in the spleen
and liver.
Abstract: The end panels of a large rectangular industrial duct,
which experience significant internal pressures, also experience
considerable transverse shear due to transfer of gravity loads to the
supports. The current design practice of such thin plate panels for
shear load is based on methods used for the design of plate girder
webs. The structural arrangements, the loadings and the resulting
behavior associated with the industrial duct end panels are, however,
significantly different from those of the web of a plate girder. The
large aspect ratio of the end panels gives rise to multiple bands of
tension fields, whereas the plate girder web design is based on one
tension field. In addition to shear, the industrial end panels are
subjected to internal pressure which in turn produces significant
membrane action. This paper reports a study which was undertaken
to review the current industrial analysis and design methods and to
propose a comprehensive method of designing industrial duct end
panels for shear resistance. In this investigation, a nonlinear finite element model was
developed to simulate the behavior of industrial duct end panel, along
with the associated edge stiffeners, subjected to transverse shear and
internal pressures. The model considered the geometric imperfections
and constitutive relations for steels. Six scale independent
dimensionless parameters that govern the behavior of such end panel
were identified and were then used in a parametric study. It was
concluded that the plate slenderness dominates the shear strength of
stockier end panels, and whereas, both the plate slenderness and the
aspect ratio influence the shear strength of slender end panels. Based
on these studies, this paper proposes design aids for estimating the
shear strength of rectangular duct end panels.
Abstract: Coal fly ash, an industrial by product of coal
combustion thermal power plants is considered as a hazardous
material and its improper disposal has become an environmental
issue. On the other hand, manufacturing conventional clay bricks
involves on consumption of large amount of clay and leads
substantial depletion of topsoil. This paper unveils the possibility of
using fly ash as a partial replacement of clay for brick manufacturing
considering the local technology practiced in Bangladesh. The effect
of fly ash with different replacing ratio (0%, 20%, 30%, 40%, and
50% by volume) of clay on properties of bricks was studied. Bricks
were made in the field parallel to ordinary bricks marked with
specific number for different percentage to identify them at time of
testing. No physical distortion is observed in fly ash brick after
burning in the kiln. Results from laboratory test show that
compressive strength of brick is decreased with the increase of fly
ash and maximum compressive strength is found to be 19.6 MPa at
20% of fly ash. In addition, water absorption of fly ash brick is
increased with the increase of fly ash. The abrasion value and
Specific gravity of coarse aggregate prepared from brick with fly ash
also studied and the results of this study suggests that 20% fly ash
can be considered as the optimum fly ash content for producing good
quality bricks utilizing present practiced technology.
Abstract: In this work, our goal is to optimize the nitriding treatment at a low-temperature of the steel 32CrMoV13 using gas mixtures of ammonia, nitrogen and hydrogen to improve the mechanical properties of the surface (good wear resistance, friction and corrosion), and of the diffusion layer of the nitrogen (good resistance to fatigue and good tenacity with heart). By limiting our work to the pure iron and to the alloys iron-chromium and iron-chromium-carbon, we have studied the various parameters which manage the nitriding: flow rate and composition of the gaseous phase, the interaction chromium-nitrogen and chromium-carbon by the help of experiments of nitriding realized in the laboratory by thermogravimetry. The acquired knowledge has been applied by the mastery of the growth of the γ' combination layer on the α diffusion layer in the case of the industrial steel 32CrMoV13.
Abstract: The goal of this paper is to specify factors influencing
the profitability of selected banks. Next, a model will be created to
help establish variables that have a demonstrable influence on the
development of the selected banks' profitability ratios. Czech banks
and their international parent companies were selected for analyzing
profitability. Banks categorized as large banks (according to the
Czech National Bank's system, which ranks banks according to
balance sheet total) were selected to represent the Czech banks. Two
ratios, the return on assets ratio (ROA) and the return on equity ratio
(ROE) are used to assess bank profitability. Six endogenous and four
external indicators were selected from among other factors that
influence bank profitability. The data analyzed were for 2001–2013.
First, correlation analysis, which was supposed to eliminate
correlated values, was conducted. A large number of correlated
values were established on the basis of this analysis. The strongly
correlated values were omitted. Despite this, the subsequent
regression analysis of profitability for the individual banks that were
selected did not confirm that the selected variables influenced their
profitability. The studied factors' influence on bank profitability was
demonstrated only for Ceskoslovenska Obchodni Banka and Société
Générale using regression analysis. For Československa Obchodni
Banka, it was demonstrated that inflation level and the amount of the
central bank's interest rate influenced the return on assets ratio and
that capital adequacy and market concentration influenced the return
on equity ratio for Société Générale.
Abstract: The aim of the study was to investigate the effect of
Saccharomyces cerevisiae (SC) live yeast culture on microbial
protein supply to small intestine in Kivircik male yearlings when fed
with different ratio of forage and concentrate diets. Four Kivircik
male yearlings with permanent rumen canula were used in the
experiment. The treatments were allocated to a 4x4 Latin square
design. Diet I consisted of 70% alfalfa hay and 30% concentrate, Diet
II consisted of 30% alfalfa hay and 70% concentrate, Diet I and II
were supplemented with a SC. Daily urine was collected and stored at
-20°C until analysis. Calorimetric methods were used for the
determination of urinary allantoin and creatinine levels. The
estimated microbial N supply to small intestine for Diets I, I+SC, II
and II+SC were 2.51, 2.64, 2.95 and 3.43 g N/d respectively.
Supplementation of Diets I and II with SC significantly affected the
allantoin levels in μmol/W0.75 (p
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: Much of the literature on research design has focused
on research conducted in developed, uni-cultural or primarily English
speaking countries. Studies of qualitative case study research, the
challenges, and prospects have been embedded in Western/Eurocentric
society and social theories. Although there have been some
theoretical studies, few empirical studies have been conducted to
explore the nature of the challenges of qualitative case study in
developing countries. These challenges include accessibility to
organizations, conducting interviews in developing countries,
accessing documents and observing official meetings, language and
cultural challenges, the use of consent forms, issues affecting access
to companies, respondent issues, and data analysis. The author, while
conducting qualitative case study research in Libya, faced all these
issues. The discussion in this paper examines these issues in order to
make a contribution toward the literature in this area.
Abstract: A model to predict the plastic zone size for material
under plane stress condition has been developed and verified
experimentally. The developed model is a function of crack size,
crack angle and material property (dislocation density). Simulation
and validation results show that the model developed show good
agreement with experimental results. Samples of low carbon steel
(0.035%C) with included surface crack angles of 45o, 50o, 60o, 70o
and 90o and crack depths of 2mm and 4mm were subjected to low
strain rate between 0.48 x 10-3 s-1 – 2.38 x 10-3 s-1. The mechanical
properties studied were ductility, tensile strength, modulus of
elasticity, yield strength, yield strain, stress at fracture and fracture
toughness. The experimental study shows that strain rate has no
appreciable effect on the size of plastic zone while crack depth and
crack angle plays an imperative role in determining the size of the
plastic zone of mild steel materials.
Abstract: We have studied the temporal characteristics of
bistable perception of the stimuli of two types: one involves
alterations in a perceived depth and another one has an ambiguous
content. We used the Necker lattice and lines of shadowed circles
ambiguously perceived either as spheres or holes as stimuli of the
first type. The Winson figure (the Eskimo/Indian picture) was a
stimulus of the second type. We have analyzed how often the
reversals occurred (reversal rate) and for how long each of the two
interpretations, or percepts, was observed during one presentation
(stability durations). For all three ambiguous images the reversal rate
and the stability durations had similar values, which provide another
evidence for a significant role of top-down processes in multistable
perception.