Abstract: Effective cooling of electronic equipment has emerged
as a challenging and constraining problem of the new century. In the
present work the feasibility and effectiveness of jet impingement
cooling on electronics were investigated numerically and
experimentally. Studies have been conducted to see the effect of the
geometrical parameters such as jet diameter (D), jet to target
spacing (Z) and ratio of jet spacing to jet diameter (Z/D) on the heat
transfer characteristics. The values of Reynolds numbers considered
are in the range 7000 to 42000. The results obtained from the
numerical studies are validated by conducting experiments. From the
studies it is found that the optimum value of Z/D ratio is 5. For a
given Reynolds number, the Nusselt number increases by about 28%
if the diameter of the nozzle is increased from 1mm to 2mm.
Correlations are proposed for Nusselt number in terms of Reynolds
number and these are valid for air as the cooling medium.
Abstract: This research aims at modeling and simulating the effects of nanofluids on cylindrical heat pipes thermal performance using the ANSYS-FLUENT CFD commercial software. The heat pipe outer wall temperature distribution, thermal resistance, liquid pressure and axial velocity in presence of suspended nano-scaled solid particle (i.e. Cu, Al2O3 and TiO2) within the fluid (water) were investigated. The effect of particle concentration and size were explored and it is concluded that the thermal performance of the heat pipe is improved when using nanofluid as the system working fluid. Additionally, it was observed that the thermal resistance of the heat pipe drops as the particle concentration level increases and particle radius decreases.
Abstract: In distributed resource allocation a set of agents must assign their resources to a set of tasks. This problem arises in many real-world domains such as distributed sensor networks, disaster rescue, hospital scheduling and others. Despite the variety of approaches proposed for distributed resource allocation, a systematic formalization of the problem, explaining the different sources of difficulties, and a formal explanation of the strengths and limitations of key approaches is missing. We take a step towards this goal by using a formalization of distributed resource allocation that represents both dynamic and distributed aspects of the problem. In this paper we present a new idea for target tracking in sensor networks and compare it with previous approaches. The central contribution of the paper is a generalized mapping from distributed resource allocation to DDCSP. This mapping is proven to correctly perform resource allocation problems of specific difficulty. This theoretical result is verified in practice by a simulation on a realworld distributed sensor network.
Abstract: Field mapping activity for an active volcano mainly in
the Torrid Zone is usually hampered by several problems such as steep
terrain and bad atmosphere conditions. In this paper we present a
simple solution for such problem by a combination Synthetic Aperture
Radar (SAR) and geostatistical methods. By this combination, we
could reduce the speckle effect from the SAR data and then estimate
roughness distribution of the pyroclastic flow deposits. The main
purpose of this study is to detect spatial distribution of new pyroclastic
flow deposits termed as P-zone accurately using the β°data from two
RADARSAT-1 SAR level-0 data. Single scene of Hyperion data and
field observation were used for cross-validation of the SAR results.
Mt. Merapi in central Java, Indonesia, was chosen as a study site and
the eruptions in May-June 2006 were examined. The P-zones were
found in the western and southern flanks. The area size and the longest
flow distance were calculated as 2.3 km2 and 6.8 km, respectively. The
grain size variation of the P-zone was mapped in detail from fine to
coarse deposits regarding the C-band wavelength of 5.6 cm.
Abstract: Located within the tropical belt region, there are
certain rules which should implemented in creating a passive
sustainable housing design in Malaysia. Traditional Malay house
possess a strong character with certain special spaces to create a
sustainable house which suit to the tropical climate in Malaysia. One
of the special space known as verandah or serambi gantung, create
various advantages in solving various issues. However, this special
space is not extremely being applied currently which produce major
issues in term of social and environmental aspects. Hence, this
phenomena create a negative impact to the occupant while Malaysia
already has a best housing design previously. Therefore, this paper
aims to explore both of the main issues mentioned above and reveal
the advantages of implementing verandah into passive sustainable
housing design in Malaysia. A systematic literature review is the
main methodology in this research to identify the various advantages
about verandah.. The study reveals that verandah is the best solution
in term of social and environmental issues and should be
implemented in current housing design in Malaysia.
Abstract: The threshold voltage and capacitance voltage characteristics of ultra-thin Silicon-on-Insulator MOSFET are greatly influenced by the thickness and doping concentration of the silicon film. In this work, the capacitance voltage characteristics and threshold voltage of the device have been analyzed with quantum mechanical effects using the Self-Consistent model. Reduction of channel thickness and adding doping impurities cause an increase in the threshold voltage. Moreover, the temperature effects cause a significant amount of threshold voltage shift. The temperature dependence of threshold voltage has also been observed with Self- Consistent approach which are well supported from experimental performance of practical devices.
Abstract: The analytical solution of functionally graded
piezoelectric hollow cylinder which is under radial electric potential
and non-axisymmetric thermo-mechanical loads, are presented in this
paper. Using complex Fourier series and estimation of power law for
variations of material characterizations through the thickness, the
electro thermo mechanical behavior of the FGPM cylinder is
obtained. The stress and displacement distributions and the effect of
electric potential field on the cylinder behavior are also presented and
some applicable results are offered at the end of the paper.
Abstract: The paper introduces and discusses definitions and concepts from the supplier relationship management area. This review has the goal to provide readers with the basic conditions to understand the market mechanisms and the technological developments of the SRM market. Further on, the work gives a picture of the actual business environment in which the SRM vendors are in, and the main trends in the field, based on the main SRM functionalities i.e. e-Procurement, e-Sourcing and Supplier Enablement, which indicates users and software providers the future technological developments and practises that will take place in this area in the next couple of years.
Abstract: In this paper, the noise maps for the area encircled by
the Second Ring Road in Riyadh city are developed based on real
measured data. Sound level meters, GPS receivers to determine
measurement position, a database program to manage the measured
data, and a program to develop the maps are used. A baseline noise
level has been established at each short-term site so subsequent
monitoring may be conducted to describe changes in Riyadh-s noise
environment. Short-term sites are used to show typical daytime and
nighttime noise levels at specific locations by short duration grab
sampling.
Abstract: Nowadays, people are going more and more mobile, both in terms of devices and associated applications. Moreover, services that these devices are offering are getting wider and much more complex. Even though actual handheld devices have considerable computing power, their contexts of utilization are different. These contexts are affected by the availability of connection, high latency of wireless networks, battery life, size of the screen, on-screen or hard keyboard, etc. Consequently, development of mobile applications and their associated mobile Web services, if any, should follow a concise methodology so they will provide a high Quality of Service. The aim of this paper is to highlight and discuss main issues to consider when developing mobile applications and mobile Web services and then propose a framework that leads developers through different steps and modules toward development of efficient and secure mobile applications. First, different challenges in developing such applications are elicited and deeply discussed. Second, a development framework is presented with different modules addressing each of these challenges. Third, the paper presents an example of a mobile application, Eivom Cinema Guide, which benefits from following our development framework.
Abstract: The need to evaluate and understand the natural
drainage pattern in a flood prone, and fast developing environment is
of paramount importance. This information will go a long way to
help the town planners to determine the drainage pattern, road
networks and areas where prominent structures are to be located. This
research work was carried out with the aim of studying the Bayelsa
landscape topography using digitized topographic information, and to
model the natural drainage flow pattern that will aid the
understanding and constructions of workable drainages. To achieve
this, digitize information of elevation and coordinate points were
extracted from a global imagery map. The extracted information was
modeled into 3D surfaces. The result revealed that the average
elevation for Bayelsa State is 12 m above sea level. The highest
elevation is 28 m, and the lowest elevation 0 m, along the coastline.
In Yenagoa the capital city of Bayelsa were a detail survey was
carried out showed that average elevation is 15 m, the highest
elevation is 25 m and lowest is 3 m above the mean sea level. The
regional elevation in Bayelsa, showed a gradation decrease from the
North Eastern zone to the South Western Zone. Yenagoa showed an
observed elevation lineament, were low depression is flanked by high
elevation that runs from the North East to the South west. Hence,
future drainages in Yenagoa should be directed from the high
elevation, from South East toward the North West and from the
North West toward South East, to the point of convergence which is
at the center that flows from South East toward the North West.
Bayelsa when considered on a regional Scale, the flow pattern is from
the North East to the South West, and also North South. It is
recommended that in the event of any large drainage construction at
municipal scale, it should be directed from North East to the South
West or from North to South. Secondly, detail survey should be
carried out to ascertain the local topography and the drainage pattern
before the design and construction of any drainage system in any part
of Bayelsa.
Abstract: Air emissions from waste treatment plants often
consist of a combination of Volatile Organic Compounds (VOCs)
and odors. Hydrogen sulfide is one of the major odorous gases
present in the waste emissions coming from municipal wastewater
treatment facilities. Hydrogen sulfide (H2S) is odorous, highly toxic
and flammable. Exposure to lower concentrations can result in eye
irritation, a sore throat and cough, shortness of breath, and fluid in
the lungs. Biofiltration has become a widely accepted technology for
treating air streams containing H2S. When compared with other nonbiological
technologies, biofilter is more cost-effective for treating large
volumes of air containing low concentrations of biodegradable compounds.
Optimization of biofilter media is essential for many reasons such as:
providing a higher surface area for biofilm growth, low pressure drop,
physical stability, and good moisture retention. In this work, a novel
biofilter media is developed and tested at a pumping station of a
municipality located in the United Arab Emirates (UAE). The
media is found to be very effective (>99%) in removing H2S
concentrations that are expected in pumping stations under steady
state and shock loading conditions.
Abstract: This work presents a matched field processing (MFP)
algorithm based on Dopplerlet transform for estimating the motion
parameters of a sound source moving along a straight line and with a
constant speed by using a piecewise strategy, which can significantly
reduce the computational burden. Monte Carlo simulation results and
an experimental result are presented to verify the effectiveness of the
algorithm advocated.
Abstract: The increasing complexity of software development based on peer to peer networks makes necessary the creation of new frameworks in order to simplify the developer-s task. Additionally, some applications, e.g. fire detection or security alarms may require real-time constraints and the high level definition of these features eases the application development. In this paper, a service model based on a component model with real-time features is proposed. The high-level model will abstract developers from implementation tasks, such as discovery, communication, security or real-time requirements. The model is oriented to deploy services on small mobile devices, such as sensors, mobile phones and PDAs, where the computation is light-weight. Services can be composed among them by means of the port concept to form complex ad-hoc systems and their implementation is carried out using a component language called UM-RTCOM. In order to apply our proposals a fire detection application is described.
Abstract: In this paper a new method for increasing the speed of
SAGCM-APD is proposed. Utilizing carrier rate equations in
different regions of the structure, a circuit model for the structure is
obtained. In this research, in addition to frequency response, the
effect of added new charge layer on some transient parameters like
slew-rate, rising and falling times have been considered. Finally, by
trading-off among some physical parameters such as different layers
widths and droppings, a noticeable decrease in breakdown voltage
has been achieved. The results of simulation, illustrate some features
of proposed structure improvement in comparison with conventional
SAGCM-APD structures.
Abstract: The rapid urbanization of cities has a bane in the form
road accidents that cause extensive damage to life and limbs. A
number of location based factors are enablers of road accidents in the
city. The speed of travel of vehicles is non-uniform among locations
within a city. In this study, the perception of vehicle users is captured
on a 10-point rating scale regarding the degree of variation in speed
of travel at chosen locations in the city. The average rating is used to
cluster locations using fuzzy c-means clustering and classify them as
low, moderate and high speed of travel locations. The high speed of
travel locations can be classified proactively to ensure that accidents
do not occur due to the speeding of vehicles at such locations. The
advantage of fuzzy c-means clustering is that a location may be a
part of more than one cluster to a varying degree and this gives a
better picture about the location with respect to the characteristic
(speed of travel) being studied.
Abstract: An empirical linearly-hyperbolic approximation of the I - V characteristic of a solar cell is presented. This approximation is based on hyperbolic dependence of a current of p-n junctions on voltage for large currents. Such empirical approximation is compared with the early proposed formal linearly-hyperbolic approximation of a solar cell. The expressions defining laws of change of parameters of formal approximation at change of a photo current of family of characteristics are received. It allows simplifying a finding of parameters of approximation on actual curves, to specify their values. Analytical calculation of load regime for linearly - hyperbolic model leads to quadratic equation. Also, this model allows to define soundly a deviation from the maximum power regime and to compare efficiency of regimes of solar cells with different parameters.
Abstract: This study was conducted to investigate the incidence
of pathogenic bacteria: Salmonella, Shigella, Escherichia coli O157
and Staphylococcus aureus in cakes and tarts collected from thirtyfive
confectionery producing and selling premises located within
Tripoli city, Libya. The results revealed an incidence of S. aureus
with 94.4 and 48.0 %, E. coli O157 with 14.7 and 4.0 % and Salmonella
sp. with 5.9 and 8.0 % in cakes and tarts samples respectively;
while Shigella was not detected in all samples. In order to determine
the source of these pathogenic bacteria, cotton swabs were taken
from the hands of workers on the production line, the surfaces of
preparation tables and cream whipping instruments. The results
showed that the cotton swabs obtained from the hands of workers
contained S. aureus and Salmonella sp. with an incidence of 42.9 and
2.9 %, the cotton swabs obtained from the surfaces of preparation
tables 22.9 and 2.9 % and the cotton swabs obtained from the cream
whipping instruments 14.3 and 0.0 % respectively; while E. coli
O157 and Shigella sp. were not detected in all swabs. Additionally,
other bacteria were isolated from the hands of workers and the Surfaces
of producing equipments included: Aeromonas sp., Pseudomonas
sp., E. coli, Klebsiella sp., Enterobacter sp., Citrobacter sp.,
Proteus sp., Serratia sp. and Acinetobacter sp. These results indicate
that some of the cakes and tarts might pose threat to consumer's
health. Meanwhile, occurrences of pathogenic bacteria on the hands
of those who are working in production line and the surfaces of
equipments reflect poor hygienic practices at most confectionery
premises examined in this study. Thus, firm and continuous surveillance
of these premises is needed to insure the consumer's health and
safety.
Abstract: Underpricing is one anomaly in initial public offerings
(IPO) literature that has been widely observed across different stock
markets with different trends emerging over different time periods.
This study seeks to determine how IPOs on the JSE performed on the
first day, first week and first month over the period of 1996-2011.
Underpricing trends are documented for both hot and cold market
periods in terms of four main sectors (cyclical, defensive, growth
stock and interest rate sensitive stocks). Using a sample of 360 listed
companies on the JSE, the empirical findings established that IPOs
on the JSE are significantly underpriced with an average market
adjusted first day return of 62.9%. It is also established that hot
market IPOs on the JSE are more underpriced than the cold market
IPOs. Also observed is the fact that as the offer price per share
increases above the median price for any given period, the level of
underpricing decreases substantially. While significant differences
exist in the level of underpricing of IPOs in the four different sectors
in the hot and cold market periods, interest rates sensitive stocks
showed a different trend from the other sectors and thus require
further investigation to uncover this pattern.
Abstract: In this paper we analyze the core issues affecting
software architecture in enterprise projects where a large number of
people at different backgrounds are involved and complex business,
management and technical problems exist. We first give general
features of typical enterprise projects and then present foundations of
software architectures. The detailed analysis of core issues affecting
software architecture in software development phases is given. We
focus on three main areas in each development phase: people,
process, and management related issues, structural (product) issues,
and technology related issues. After we point out core issues and
problems in these main areas, we give recommendations for
designing good architecture. We observed these core issues and the
importance of following the best software development practices and
also developed some novel practices in many big enterprise
commercial and military projects in about 10 years of experience.