Abstract: Numerical simulations are performed for laminar
continuous and pulsed jets impinging on a surface in order to
investigate the effects of pulsing frequency on the heat transfer
characteristics. The time-averaged Nusselt number of pulsed jets is
larger in the impinging jet region as compared to the continuous jet,
while it is smaller in the outer wall jet region. At the stagnation point,
the mean and RMS Nusselt numbers become larger and smaller,
respectively, as the pulsing frequency increases. Unsteady behaviors
of vortical fluid motions and temperature field are also investigated to
understand the underlying mechanisms of heat transfer enhancement.
Abstract: Risk of infectious disease outbreaks is related to the
hygiene among the population. To assess the actual risks and modify
the relevant emergency procedures if necessary, a hygiene survey
was conducted among undergraduate students on the Rhodes
University campus. Soap was available to 10.5% and only 26.8% of
the study participants followed proper hygiene in relation to food
consumption. This combination increases the risk of infectious
disease outbreaks at the campus. Around 83.6% were willing to wash
their hands if soap was provided. Procurement and availability of
soap in undergraduate residences on campus should be improved, as
the total cost is estimated at only 2000 USD per annum. Awareness
campaigns about food-related hygiene and the need for regular handwashing
with soap should be run among Rhodes University students.
If successful, rates of respiratory and hygiene-related diseases will be
decreased and emergency health management simplified.
Abstract: One of the criteria in production scheduling is Make
Span, minimizing this criteria causes more efficiently use of the
resources specially machinery and manpower. By assigning some
budget to some of the operations the operation time of these activities
reduces and affects the total completion time of all the operations
(Make Span). In this paper this issue is practiced in parallel flow
shops. At first we convert parallel flow shop to a network model and
by using a linear programming approach it is identified in order to
minimize make span (the completion time of the network) which
activities (operations) are better to absorb the predetermined and
limited budget. Minimizing the total completion time of all the
activities in the network is equivalent to minimizing make span in
production scheduling.
Abstract: This paper presents modeling and simulation of Grid Connected Photovoltaic (PV) system by using improved mathematical model. The model is used to study different parameter variations and effects on the PV array including operating temperature and solar irradiation level. In this paper stepped P&O algorithm is proposed for MPPT control. This algorithm will identify the suitable duty ratio in which the DC-DC converter should be operated to maximize the power output. Photo voltaic array with proposed stepped P&O-MPPT controller can operate in the maximum power point for the whole range of solar data (irradiance and temperature).
Abstract: Today with the rapid growth of telecommunications equipment, electronic and developing more and more networks of power, influence of electromagnetic waves on one another has become hot topic discussions. So in this article, this issue and appropriate mechanisms for EMC operations have been presented. First, impact of high voltage lines on the surrounding environment especially on the control room has been investigated, then to reduce electromagnetic radiation, various methods of shielding are provided and shielding effectiveness of them has been compared. It should be expressed that simulations have been done by the finite element method (FEM).
Abstract: Seismic qualification testing for equipments to be
mounted on upper storeys of buildings is very demanding in terms of
floor spectra. The latter is characterized by high accelerations
amplitudes within a narrow frequency band. This article presents a
method which permits to cover specified required response spectra
beyond the shaking table capability by amplifying the acceleration
amplitudes at an appropriate frequency range using a physical
intermediate mounted on the platform of the shaker.
Abstract: Information is increasing in volumes; companies are overloaded with information that they may lose track in getting the intended information. It is a time consuming task to scan through each of the lengthy document. A shorter version of the document which contains only the gist information is more favourable for most information seekers. Therefore, in this paper, we implement a text summarization system to produce a summary that contains gist information of oil and gas news articles. The summarization is intended to provide important information for oil and gas companies to monitor their competitor-s behaviour in enhancing them in formulating business strategies. The system integrated statistical approach with three underlying concepts: keyword occurrences, title of the news article and location of the sentence. The generated summaries were compared with human generated summaries from an oil and gas company. Precision and recall ratio are used to evaluate the accuracy of the generated summary. Based on the experimental results, the system is able to produce an effective summary with the average recall value of 83% at the compression rate of 25%.
Abstract: Weather disaster events were frequent and caused loss
of lives and property in Taiwan recently. Excessive concentration of
population and lacking of integrated planning led to Taiwanese coastal
zone face the impacts of climate change directly. Comparing to many
countries which have already set up legislation, competent authorities
and national adaptation strategies, the ability of coastal management
adapting to climate change is still insufficient in Taiwan. Therefore, it
is necessary to establish a complete institutional arrangement for
coastal management due to climate change in order to protect
environment and sustain socio-economic development. This paper
firstly reviews the impact of climate change on Taiwanese coastal
zone. Secondly, development of Taiwanese institutional arrangement
of coastal management is introduced. Followed is the analysis of four
dimensions of legal basis, competent authority, scientific and financial
support and international cooperations of institutional arrangement.
The results show that Taiwanese government shall: 1) integrate climate
change issue into Coastal Act, Wetland Act and territorial planning
Act and pass them; 2) establish the high level competent authority for
coastal management; 3) set up the climate change disaster coordinate
platform; 4) link scientific information and decision markers; 5)
establish the climate change adjustment fund; 6) participate in
international climate change organizations and meetings actively; 7)
cooperate with near countries to exchange experiences.
Abstract: The AL-MAJIRI school system is a variant of private
Arabic and Islamic schools which cater for the religious and moral development of Muslims. In the past, the system produced clerics,
scholars, judges, religious reformers, eminent teachers and great men who are worthy of emulation, particularly in northern Nigeria.
Gradually, the system lost its glory but continued to discharge its
educational responsibilities to a certain extent. This paper takes a
look at the activities of the AL-MAJIRI schools. The introduction
provides background information about Nigeria where the schools
operate. This is followed by an overview of the Nigerian educational system, the nature and the features of the AL-MAJIRI school system,
its weaknesses and the current challenges facing the schools. The paper concludes with emphasis on the urgent need for a comprehensive reform of the curriculum content of the schools. The step by step procedure required for the reform is discussed.
Abstract: The Kinetics formation of labile Complex
Ag (I) tetra (p-carboxyphenyl) porphyrin, was investigated at 25oC
and I=0.1M (NaNO3). By spectrophotometric titration, the
composition ratio of the complex was established to be 2:1
(Ag : H2TCPP). The equilibrium constant, K, was found to be
log 10-6.53. Binding of the first Ag (I) was found to be rate
determining step with rate constant, k1= 4.67×102 . A plausible
mechanism is discussed. We discus theoretically why Ag(I)2TCPP is
unstable.
Abstract: Wireless sensor networks (WSN) are currently
receiving significant attention due to their unlimited potential. These
networks are used for various applications, such as habitat
monitoring, automation, agriculture, and security. The efficient nodeenergy
utilization is one of important performance factors in wireless
sensor networks because sensor nodes operate with limited battery
power. In this paper, we proposed the MiSense hierarchical cluster
based routing algorithm (MiCRA) to extend the lifetime of sensor
networks and to maintain a balanced energy consumption of nodes.
MiCRA is an extension of the HEED algorithm with two levels of
cluster heads. The performance of the proposed protocol has been
examined and evaluated through a simulation study. The simulation
results clearly show that MiCRA has a better performance in terms of
lifetime than HEED. Indeed, MiCRA our proposed protocol can
effectively extend the network lifetime without other critical
overheads and performance degradation. It has been noted that there
is about 35% of energy saving for MiCRA during the clustering
process and 65% energy savings during the routing process compared
to the HEED algorithm.
Abstract: Synthesis gas manufacturing by steam reforming of hydrocarbons is an important industrial process. High endothermic nature of the process makes it one of the most cost and heat intensive processes. In the present work, composite effect of different inert gases on synthesis gas yield, feed gas conversion and temperature distribution along the reactor length has been studied using a heterogeneous model. Mathematical model was developed as a first stage and validated against the existing process models. With the addition of inert gases, a higher yield of synthesis gas is observed. Simultaneously the rector outlet temperature drops to as low as 810 K. It was found that Xenon gives the highest yield and conversion while Helium gives the lowest temperature. Using Xenon inert gas 20 percent reduction in outlet temperature was observed compared to traditional case.
Abstract: This paper presents two simplified models to
determine nodal voltages in power distribution networks. These
models allow estimating the impact of the installation of reactive
power compensations equipments like fixed or switched capacitor
banks. The procedure used to develop the models is similar to the
procedure used to develop linear power flow models of transmission
lines, which have been widely used in optimization problems of
operation planning and system expansion. The steady state non-linear
load flow equations are approximated by linear equations relating the
voltage amplitude and currents. The approximations of the linear
equations are based on the high relationship between line resistance
and line reactance (ratio R/X), which is valid for power distribution
networks. The performance and accuracy of the models are evaluated
through comparisons with the exact results obtained from the
solution of the load flow using two test networks: a hypothetical
network with 23 nodes and a real network with 217 nodes.
Abstract: As a result of urbanization, the unpredictable growth of industry and transport, production of chemicals, military activities, etc. the concentration of anthropogenic toxicants spread in nature exceeds all the permissible standards. Most dangerous among these contaminants are organic compounds having great persistence, bioaccumulation, and toxicity along with our awareness of their prominent occurrence in the environment and food chain. Among natural ecological tools, plants still occupying above 40% of the world land, until recently, were considered as organisms having only a limited ecological potential, accumulating in plant biomass and partially volatilizing contaminants of different structure. However, analysis of experimental data of the last two decades revealed the essential role of plants in environment remediation due to ability to carry out intracellular degradation processes leading to partial or complete decomposition of carbon skeleton of different structure contaminants. Though, phytoremediation technologies still are in research and development, their various applications have been successfully used. The paper aims to analyze mechanisms of organic contaminants uptake and detoxification in plants, being the less studied issue in evaluation and exploration of plants potential for environment remediation.
Abstract: In some real applications of Statistical Process Control
it is necessary to design a control chart to not detect small process
shifts, but keeping a good performance to detect moderate and large
shifts in the quality. In this work we develop a new quality control
chart, the synthetic T2 control chart, that can be designed to cope with
this objective. A multi-objective optimization is carried out employing
Genetic Algorithms, finding the Pareto-optimal front of
non-dominated solutions for this optimization problem.
Abstract: This research was conducted for the first time at the
southeastern coasts of the Caspian Sea in order to evaluate the
performance of osteichthyes cooperatives through production (catch)
function. Using one of the indirect valuation methods in this research,
contributory factors in catch were identified and were inserted into
the function as independent variables. In order to carry out this
research, the performance of 25 Osteichthyes catching cooperatives
in the utilization year of 2009 which were involved in fishing in
Miankale wildlife refuge region. The contributory factors in catch
were divided into groups of economic, ecological and biological
factors. In the mentioned function, catch rate of the cooperative were
inserted into as the dependant variable and fourteen partial variables
in terms of nine general variables as independent variables. Finally,
after function estimation, seven variables were rendered significant at
99 percent reliably level. The results of the function estimation
indicated that human resource (fisherman quantity) had the greatest
positive effect on catch rate with an influence coefficient of 1.7 while
weather conditions had the greatest negative effect on the catch rate
of cooperatives with an influence coefficient of -2.07. Moreover,
factors like member's share, experience and fisherman training and
fishing effort played the main roles in the catch rate of cooperative
with influence coefficients of 0.81, 0.5 and 0.21, respectively.
Abstract: A 10bit, 40 MSps, sample and hold, implemented in 0.18-μm CMOS technology with 3.3V supply, is presented for application in the front-end stage of an analog-to-digital converter. Topology selection, biasing, compensation and common mode feedback are discussed. Cascode technique has been used to increase the dc gain. The proposed opamp provides 149MHz unity-gain bandwidth (wu), 80 degree phase margin and a differential peak to peak output swing more than 2.5v. The circuit has 55db Total Harmonic Distortion (THD), using the improved fully differential two stage operational amplifier of 91.7dB gain. The power dissipation of the designed sample and hold is 4.7mw. The designed system demonstrates relatively suitable response in different process, temperature and supply corners (PVT corners).
Abstract: This paper describes a CMOS four-quadrant
multiplier intended for use in the front-end receiver by utilizing the
square-law characteristic of the MOS transistor in the saturation
region. The circuit is based on 0.35 um CMOS technology simulated
using HSPICE software. The mixer has a third-order inter the power
consumption is 271uW from a single 1.2V power supply. One of the
features of the proposed design is using two MOS transistors
limitation to reduce the supply voltage, which leads to reduce the
power consumption. This technique provides a GHz bandwidth
response and low power consumption.
Abstract: In-core memory requirement is a bottleneck in solving
large three dimensional Navier-Stokes finite element problem
formulations using sparse direct solvers. Out-of-core solution
strategy is a viable alternative to reduce the in-core memory
requirements while solving large scale problems. This study
evaluates the performance of various out-of-core sequential solvers
based on multifrontal or supernodal techniques in the context of
finite element formulations for three dimensional problems on a
Windows platform. Here three different solvers, HSL_MA78,
MUMPS and PARDISO are compared. The performance of these
solvers is evaluated on a 64-bit machine with 16GB RAM for finite
element formulation of flow through a rectangular channel. It is
observed that using out-of-core PARDISO solver, relatively large
problems can be solved. The implementation of Newton and
modified Newton's iteration is also discussed.
Abstract: The research objective of the project and article
“European Ecological Network Natura 2000 – opportunities and
threats” Natura 2000 sites constitute a form of environmental
protection, several legal problems are likely to result. Most
controversially, certain sites will be subject to two regimes of
protection: as national parks and as Natura 2000 sites. This dualism
of the legal regulation makes it difficult to perform certain legal
obligations related to the regimes envisaged under each form of
environmental protection. Which regime and which obligations
resulting from the particular form of environmental protection have
priority and should prevail? What should be done if these obligations
are contradictory? Furthermore, an institutional problem consists in
that no public administration authority has the power to resolve legal
conflicts concerning the application of a particular regime on a given
site. There are also no criteria to decide priority and superiority of
one form of environmental protection over the other. Which
regulations are more important, those that pertain to national parks or
to Natura 2000 sites? In the light of the current regulations, it is
impossible to give a decisive answer to these questions. The internal
hierarchy of forms of environmental protection has not been
determined, and all such forms should be treated equally.