Abstract: A potential flow model is used to study the unsteady
flow past two airfoils in configuration, each of which is suddenly set
into motion. The airfoil bound vortices are modeled using lumped
vortex elements and the wake behind the airfoil is modeled by discrete
vortices. This consists of solving a steady state flow problem at each
time-step where unsteadiness is incorporated through the “zero normal
flow on a solid surface" boundary condition at every time instant.
Additionally, along with the “zero normal flow on a solid surface"
boundary condition Kelvin-s condition is used to compute the strength
of the latest wake vortex shed from the trailing edge of the airfoil.
Location of the wake vortices is updated at each time-step to get the
wake shape at each time instant. Results are presented to show the
effect of airfoil-airfoil interaction and airfoil-wake interaction on the
aerodynamic characteristics of each airfoil.
Abstract: This paper propose a new circuit design which
monitor total leakage current during standby mode and generates the
optimal reverse body bias voltage, by using the adaptive body bias
(ABB) technique to compensate die-to-die parameter variations.
Design details of power monitor are examined using simulation
framework in 65nm and 32nm BTPM model CMOS process.
Experimental results show the overhead of proposed circuit in terms
of its power consumption is about 10 μW for 32nm technology and
about 12 μW for 65nm technology at the same power supply voltage
as the core power supply. Moreover the results show that our
proposed circuit design is not far sensitive to the temperature
variations and also process variations. Besides, uses the simple
blocks which offer good sensitivity, high speed, the continuously
feedback loop.
Abstract: Nonlinear system identification is becoming an important tool which can be used to improve control performance. This paper describes the application of adaptive neuro-fuzzy inference system (ANFIS) model for controlling a car. The vehicle must follow a predefined path by supervised learning. Backpropagation gradient descent method was performed to train the ANFIS system. The performance of the ANFIS model was evaluated in terms of training performance and classification accuracies and the results confirmed that the proposed ANFIS model has potential in controlling the non linear system.
Abstract: This research uses computational linguistics, an area of study that employs a computer to process natural language, and aims at discerning the patterns that exist in declarative sentences used in technical texts. The approach is mathematical, and the focus is on instructional texts found on web pages. The technique developed by the author and named the MAYA Semantic Technique is used here and organized into four stages. In the first stage, the parts of speech in each sentence are identified. In the second stage, the subject of the sentence is determined. In the third stage, MAYA performs a frequency analysis on the remaining words to determine the verb and its object. In the fourth stage, MAYA does statistical analysis to determine the content of the web page. The advantage of the MAYA Semantic Technique lies in its use of mathematical principles to represent grammatical operations which assist processing and accuracy if performed on unambiguous text. The MAYA Semantic Technique is part of a proposed architecture for an entire web-based intelligent tutoring system. On a sample set of sentences, partial semantics derived using the MAYA Semantic Technique were approximately 80% accurate. The system currently processes technical text in one domain, namely Cµ programming. In this domain all the keywords and programming concepts are known and understood.
Abstract: Like other external sorting algorithms, the presented
algorithm is a two step algorithm including internal and external
steps. The first part of the algorithm is like the other similar
algorithms but second part of that is including a new easy
implementing method which has reduced the vast number of inputoutput
operations saliently. As decreasing processor operating time
does not have any effect on main algorithm speed, any improvement
in it should be done through decreasing the number of input-output
operations. This paper propose an easy algorithm for choose the
correct record location of the final list. This decreases the time
complexity and makes the algorithm faster.
Abstract: Protection system hidden failures have been identified as one of the main causes of system cascading collapse resulting to power system instability. In this paper, a systematic approach is presented in order to identify the probability of a system cascading collapse by taking into consideration the effect of protection system hidden failure. This includes the accurate calculation of the probability of hidden failure as it will provide significant impinge on the findings of the probability of system cascading collapse. The probability of a system cascading collapse is then used to identify the initial tripping of sensitive transmission lines which will contribute to a critical system cascading collapse. Based on the results obtained from this study, it is important to decide on the accurate value of the hidden failure probability as it will affect the probability of a system cascading collapse.
Abstract: Composite nanostructures of metal
core/semiconductor shell (Au/CdS) configuration were prepared
using organometalic method. UV-Vis spectra for the Au/CdS colloids
show initially two well separated bands, corresponding to surface
plasmon of the Au core, and the exciton of CdS shell. The absorption
of CdS shell is enhanced, while the Au plasmon band is suppressed
as the shell thickness increases. The shell sizes were estimated from
the optical spectra using the effective mass approximation model
(EMA), and compared to the sizes of the Au core and CdS shell
measured by high resolution transmission electron microscope
(HRTEM). The changes in the absorption features are discussed in
terms of gradual increase in the coupling strength of the Au core
surface plasmon and the exciton in the CdS. leading to charge
transfer and modification of electron oscillation in Au core.
Abstract: Ambient hydrolysis products in moist air and
hydrolysis kinetics in argon with humidity of RH1.5% for
polycrystalline LiH powders and sintered bulks were investigated by
X-ray diffraction, Raman spectroscopy and gravimetry. The results
showed that the hydrolysis products made up a layered structure of
LiOH•H2O/LiOH/Li2O from surface of the sample to inside. In low
humid argon atmosphere, the primary hydrolysis product was Li2O
rather than LiOH. The hydrolysis kinetic curves of LiH bulks present a
paralinear shape, which could be explained by the “Layer Diffusion
Control" model. While a three-stage hydrolysis kinetic profile was
observed for LiH powders under the same experimental conditions.
The first two sections were similar to that of the bulk samples, and the
third section also presents a linear reaction kinetics but with a smaller
reaction rate compared to the second section because of a larger
exothermic effect for the hydrolysis reaction of LiH powder.
Abstract: The present paper deals with problems related to the
possibilities to use fractal systems to solve some important scientific
and practical problems connected with filtering and separation of
aqueous phases from organic ones. For this purpose a special
separator have been designed. The reactor was filled with a porous
material with fractal dimension, which is an integral part of the set
for filtration and separation of emulsions. As a model emulsion
hexadecan mixture with water in equal quantities (1:1) was used. We
examined the hydrodynamics of the separation of the emulsion at
different rates of submission of the entrance of the reactor.
Abstract: Visual secret sharing (VSS) was proposed by Naor and Shamir in 1995. Visual secret sharing schemes encode a secret image into two or more share images, and single share image can’t obtain any information about the secret image. When superimposes the shares, it can restore the secret by human vision. Due to the traditional VSS have some problems like pixel expansion and the cost of sophisticated. And this method only can encode one secret image. The schemes of encrypting more secret images by random grids into two shares were proposed by Chen et al. in 2008. But when those restored secret images have much distortion, those schemes are almost limited in decoding. In the other words, if there is too much distortion, we can’t encrypt too much information. So, if we can adjust distortion to very small, we can encrypt more secret images. In this paper, four new algorithms which based on Chang et al.’s scheme be held in 2010 are proposed. First algorithm can adjust distortion to very small. Second algorithm distributes the distortion into two restored secret images. Third algorithm achieves no distortion for special secret images. Fourth algorithm encrypts three secret images, which not only retain the advantage of VSS but also improve on the problems of decoding.
Abstract: Text categorization - the assignment of natural language documents to one or more predefined categories based on their semantic content - is an important component in many information organization and management tasks. Performance of neural networks learning is known to be sensitive to the initial weights and architecture. This paper discusses the use multilayer neural network initialization with decision tree classifier for improving text categorization accuracy. An adaptation of the algorithm is proposed in which a decision tree from root node until a final leave is used for initialization of multilayer neural network. The experimental evaluation demonstrates this approach provides better classification accuracy with Reuters-21578 corpus, one of the standard benchmarks for text categorization tasks. We present results comparing the accuracy of this approach with multilayer neural network initialized with traditional random method and decision tree classifiers.
Abstract: The paper deals with the analysis of the dynamic
response of footbridges under human - induced dynamic loads.
This is a frequently occurring and often dominant load for
footbridges as it stems from the very purpose of a footbridge - to
convey pedestrian. Due to the emergence of new materials and
advanced engineering technology, slender footbridges are
increasingly becoming popular to satisfy the modern transportation
needs and the aesthetical requirements of the society. These
structures however are always lively with low stiffness, low mass,
low damping and low natural frequencies. As a consequence, they are
prone to vibration induced by human activities and can suffer severe
vibration serviceability problems, particularly in the lateral direction.
Pedestrian bridges are designed according to first and second limit
states, these are the criteria involved in response to static design load.
However, it is necessary to assess the dynamic response of bridge
design load on pedestrians and assess it impact on the comfort of the
user movement. Usually the load is considered a person or a small
group which can be assumed in perfect motion synchronization.
Already one person or small group can excite significant vibration of
the deck. In order to calculate the dynamic response to the movement
of people, designer needs available and suitable computational model
and criteria. For the calculation program ANSYS based on finite
element method was used.
Abstract: The wireless mesh networks (WMNs) are emerging technology in wireless networking as they can serve large scale high speed internet access. Due to its wireless multi-hop feature, wireless mesh network is prone to suffer from many attacks, such as denial of service attack (DoS). We consider a special case of DoS attack which is selective forwarding attack (a.k.a. gray hole attack). In such attack, a misbehaving mesh router selectively drops the packets it receives rom its predecessor mesh router. It is very hard to detect that packet loss is due to medium access collision, bad channel quality or because of selective forwarding attack. In this paper, we present a review of detection algorithms of selective forwarding attack and discuss their advantage & disadvantage. Finally we conclude this paper with open research issues and challenges.
Abstract: Multiple-Input-Multiple-Output (MIMO) is one of the most important communication techniques that allow wireless systems to achieve higher data rate. To overcome the practical difficulties in implementing Dirty Paper Coding (DPC), various suboptimal MIMO Broadcast (MIMO-BC) scheduling algorithms are employed which choose the best set of users among all the users. In this paper we discuss such a sub-optimal MIMO-BC scheduling algorithm which employs antenna selection at the receiver side. The channels for the users considered here are not Identical and Independent Distributed (IID) so that users at the receiver side do not get equal opportunity for communication. So we introduce a method of applying weights to channels of the users which are not IID in such a way that each of the users gets equal opportunity for communication. The effect of weights on overall sum-rate achieved by the system has been investigated and presented.
Abstract: The authors present an optimization algorithm for order reduction and its application for the determination of the relative mapping errors of linear time invariant dynamic systems by the simplified models. These relative mapping errors are expressed by means of the relative integral square error criterion, which are determined for both unit step and impulse inputs. The reduction algorithm is based on minimization of the integral square error by particle swarm optimization technique pertaining to a unit step input. The algorithm is simple and computer oriented. It is shown that the algorithm has several advantages, e.g. the reduced order models retain the steady-state value and stability of the original system. Two numerical examples are solved to illustrate the superiority of the algorithm over some existing methods.
Abstract: In this article, a single application is suggested to determine the position of vehicles using Geographical Information Systems (GIS) and Geographical Position Systems (GPS). The part of the article material included mapping three dimensional coordinates to two dimensional coordinates using UTM or LAMBERT geographical methods, and the algorithm of conversion of GPS information into GIS maps is studied. Also, suggestions are given in order to implement this system based on web (called web based systems). To apply this system in IRAN, related official in this case are introduced and their duties are explained. Finally, economy analyzed is assisted according to IRAN communicational system.
Abstract: Face authentication for access control is a face
membership authentication which passes the person of the incoming
face if he turns out to be one of an enrolled person based on face
recognition or rejects if not. Face membership authentication belongs
to the two class classification problem where SVM(Support Vector
Machine) has been successfully applied and shows better performance
compared to the conventional threshold-based classification. However,
most of previous SVMs have been trained using image feature vectors
extracted from face images of each class member(enrolled
class/unenrolled class) so that they are not robust to variations in
illuminations, poses, and facial expressions and much affected by
changes in member configuration of the enrolled class
In this paper, we propose an effective face membership
authentication method based on SVM using class discriminating
features which represent an incoming face image-s associability with
each class distinctively. These class discriminating features are weakly
related with image features so that they are less affected by variations
in illuminations, poses and facial expression.
Through experiments, it is shown that the proposed face
membership authentication method performs better than the threshold
rule-based or the conventional SVM-based authentication methods and
is relatively less affected by changes in member size and membership.
Abstract: As the Social network game(SNG) is rising
dramatically worldwide, an interesting aspect has appeared in the
demographic analysis. That is the ratio of the game users by gender.
Although the ratio of male and female users in online game was
60:40% previously, the ratio of male and female users in SNG stood at
47:53% which shows that the ratio of female users is higher than that
of male users. Here, it should be noted that 35% in those 53% female
users are the first-time users of game. This fact suggests that women
who were not interested in game previously has taken an interest in
SNG. Notwithstanding this issue, there have been little studies on the
female users of SNG although there are many studies that analyzed the
tendency of female users- online game play. This study conducted the
analyzed how the game-playing tendency of SNG gamers was
manifested in the game by gender. For that, this study will identify the
tendency of SNG users by gender based on the preceding studies that
analyzed the online game users by gender. The subject of this study
was confined to the farm and urban construction simulation games
which were offered based on the mobile application platform.
Regarding the methodology of study, the first focus group
interview(FGI) was conducted with the male and female users who
had played games on Social network service(SNS) until recently. Later,
the second one-on-one in-depth interview was conducted to gain an
insight into the psychological state of the subjects.
Abstract: This article describes a Web pages automatic filtering system. It is an open and dynamic system based on multi agents architecture. This system is built up by a set of agents having each a quite precise filtering task of to carry out (filtering process broken up into several elementary treatments working each one a partial solution). New criteria can be added to the system without stopping its execution or modifying its environment. We want to show applicability and adaptability of the multi-agents approach to the networks information automatic filtering. In practice, most of existing filtering systems are based on modular conception approaches which are limited to centralized applications which role is to resolve static data flow problems. Web pages filtering systems are characterized by a data flow which varies dynamically.
Abstract: Research and development R&D work involves
enormous amount of work that has to do with data measurement and
collection. This process evolves as new information is fed, new
technologies are utilized, and eventually new knowledge is created
by the stakeholders i.e., researchers, clients, and end-users. When
new knowledge is created, procedures of R&D work should evolve
and produce better results within improved research skills and
improved methods of data measurements and collection. This
measurement improvement should then be benchmarked against a
metric that should be developed at the organization. In this paper, we
are suggesting a conceptual metric for R&D work performance
improvement (PI) at the Kuwait Institute for Scientific Research
(KISR). This PI is to be measured against a set of variables in the
suggested metric, which are more closely correlated to organizational
output, as opposed to organizational norms. The paper also mentions
and discusses knowledge creation and management as an addedvalue
to R&D work and measurement improvement. The research
methodology followed in this work is qualitative in nature, based on
a survey that was distributed to researchers and interviews held with
senior researchers at KISR. Research and analyses in this paper also
include looking at and analyzing KISR-s literature.