October 2009, No. 4
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TS-PVM: A Fault Tolerant PVM
Extension for Real Time Applications

Usama Badawi
Department of Mathematics, Faculty of Science, Egypt

Abstract: In this research work, a fault tolerant extension of the de facto message passing system parallel virtual machine, TS- parallel virtual machine, is introduced. This extension enables real time applications over parallel virtual machine. In PVM and similar message passing systems, if the message receiver is not available, due to network failure or machine crash, a failure is reported and data must be resent. If the transferred data is persistent, i.e. should not be lost, then it is important to provide the system with failure recovery mechanisms. The idea behind the proposed extension, TS- parallel virtual machine, is to integrate a fault tolerant distributed shared memory layer, in parallel virtual machine. Such layer has been inherited from the TRIPS system that supports fault tolerance over a DSM. The challenge of this research work is the integration of a DSM layer in a message passing system. The proposed parallel virtual machine extension would have bad performance if compared to the pure message passing one. On the other hand, the real time application can be completed in spite of failures occurrence.  

Keywords: Fault tolerance, persistent data, PVM, real time applications, tuple space.

Received January 14, 2007; accepted May 12, 2008

 
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The Effect of Computer Assisted Language Learning in Teaching English Grammar on the Achievement of Secondary Students in Jordan

Abdallah Abu Naba'h1, Jebreen Hussain1, Aieman Al-Omari2, and Sadeq Shdeifat1
1Department of Curricula and Instruction, The Hashemite University, Jordan
2Department of Educational Foundations and Administration, The Hashemite University, Jordan

Abstract: This study aimed at investigating the effect of using an instructional software program of English language on the achievement of secondary students in Jordan. The sample of the study consisted of (212) students distributed randomly on four experimental groups and four control groups. The instruments of the study were an instructional software program for teaching the passive voice and an achievement test. An Analysis of covariance was used to find out the effect of the instructional program on the students’ achievement in the passive voice.   The findings of the study revealed that: 1. there were statistically significant differences (a < 0.05) between the students' achievement mean scores in grammar attributed to the instructional method of teaching. This difference is in favor of the students in the experimental group 2. there were statistically significant differences (a < 0.05) between the students' achievement mean scores in grammar attributed to gender. This difference is in favor of male students. 3. there were statistically significant differences (a < 0.05) between the students' achievement mean scores in grammar attributed to stream of study. This difference is in favor of the scientific stream students. In light of the findings of the study, it was recommended that TEFL teachers use CAI lessons in their instruction.

Keywords: Computer assisted language learning, achievement, use of instructional program.

Received November 21, 2007; accepted May 25, 2008

 
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Survivable System by Critical Service Recovery Model: Single Service Analysis

Irving Paputungan and Azween Abdullah
Computer and Information Science Department, University Technology Patroness, Malaysia

Abstract: This paper reported another recovery model to enhance system survivability. The model focuses on how to preserve the system and resume its critical service while incident occurs by reconfiguring the damaged critical service resources based on available resources without affecting the stability and functioning of the system. There are three critical requisite conditions in this recovery model: the number of pre-empted non-critical service resources, the response time of resource allocation, and the cost of reconfiguration, which are used in some scenarios to find and re-allocate the available resource for the reconfiguration. To validate the viability of the approach, one instance case is provided. The adoption of fault-tolerance and survivability using redundancy re-allocation in this recovery model is discussed from a new perspective.

Keywords: Critical service, recovery, resources reconfiguration, survivability.

 Received August 16, 2007; accepted May 12, 2008

 
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Multi Purpose Code GenerationUsing Fingerprint Images

Bashar Ne’ma and Hamza Ali
Software Engineering Department, Isra Private University, Jordan

Abstract: Extracting minutia and other features from fingerprint images is one of the most important steps in automatic fingerprint identification and classification. This paper proposes a method for the generation of long and secure code that may be used for multi-purpose applications, such as ATM, coded door locks and other security measures. The method consists of two phases; the first phase is carried out using fingerprint image enhancement and thinning. The second phase consists of extracting minutia, ridge ending, bifurcation and all other features in order to produce initial pattern. Finally the multi-purposes secure code is generated by applying the one-way MD5 hash function on that pattern. The achieved results are discussed for security improvement. The proposed technique also shows considerable improvement in the minutia detection process in terms of both efficiency and speed.

Keywords:

Fingerprint matching, image enhancement, reference point, code generation, embedded system.

 Received December 31, 2007; accepted May 22, 2008

  

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Clustering Items in Different Data
Sources Induced by Stability

Jhimli Adhikari1, Pralhad Rao2, and Animesh Adhikari3
1Department of Computer Science, Narayan Zantye College, India
2Department of Computer Scence and Tecnology, India
3Department of Computer Science, Chowgule College, India

Abstract: Many multi-branch companies transact from different branches. Each branch of such a company maintains a separate database over time. The variation of sales of an item over time is an important issue. Thus, we introduce the notion of stability of an item. Stable items are useful in making many strategic decisions for a company. Based on the degree of stability of an item, we design an algorithm for clustering items in different data sources. We have proposed the notion of best cluster by considering average degree of variation of a class. Also, we have designed an alternative algorithm to find best cluster among items in different data sources.  Experimental results are provided on three transactional databases.

Keywords: Clustering, data mining, dispersion, multiple databases, stability.

Received March 12, 2007; accepted May 20, 2008

 
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Mobility and QoS of 802.11 and 802.11e
Wireless LAN Standards

Fedoua Didi1, Houda Labiod2, Guy Pujolle3, and Mohamed Feham1
1Department of the University of Tlemcen, University Abou Bekr Belkaid of Tlemcen, Algeria
2Department INFRES in Computer Science, Enst of Paris, France
3University Pierre and Marie Curie, France

Abstract: Quality of service is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN are the most widely used WLAN standards today, and the  IEEE 802.11e quality of service enhancement standard exists and introduces quality of service support for multimedia applications. This paper compares the propositions of standard IEEE 802.11e with the standard IEEE 802.11 without quality of service, a simulation of these standards is performed by using the network simulator simulator. We test also the mobility and the roaming of stations. A discussion is presented in detail using simulation-based evaluations and we let us confirm the quality of service of IEEE 802.11e compared to IEEE 802.11, but we have detected some weaknesses of 802.11e. It starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate of weight of queues, so there is an unbalance enters the flows with high priorities.

Keywords: IEEE 802.11, Medium access control, quality of service, distributed coordination function, point coordination function, hybrid coordination function.

Received January 18, 2008; accepted May 20, 2008

 
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Fuzzy and Neuro-Fuzzy Modeling of
a Fermentation Process

Chabbi Charef1, Mahmoud Taibi1, and Nicole Vincent2
1Electronics Department, University of Annaba, Algeria
2Laboratory CRIP5-SIP, University René Descartes Paris, France

Abstract: Neuro-fuzzy modeling may be qualified as a grey-box technique, since it combines the transparency of rule-based fuzzy systems with the learning capability of neural networks. The main problem in the identification of non-linear processes is the lack of complete information. Certain variables are, either immeasurable or difficult to measure, the soft sensors are the necessary tools to solve the problem. Those latter can be used via online estimation, and then they will be implemented in fed-batch fermentation processes for optimal production and online monitoring. The process parameters are estimated through a fuzzy logic system. The fuzzy models of takagi-sugeno type suffer of the problem of poor initialization, which can be solved by the trial-and error method Trial-and-error method is used to solve the poor initialization problem of TS models, this deals with identifying the structure of the model, such structure consists on finding the optimum number of rules, which enters in the model cost reduction. The fuzzy model might not capture the process non-linearity, especially if the number of rules is over-optimized. Bioreactors exhibit a wide range of dynamic behaviours and offer many challenges to modeling, as a result of the presence of living micro-organisms whose growth rate is described by complex equations. We will illustrate the fuzzy and the neuro-fuzzy modeling on the identification of such a system. In order to compare the NF model outputs, we     use another fuzzy model that does not incorporate the neural network learning capability, to identify the parameters of the same process. Even though, the two models were trained using levenberg-marquardt algorithm, the corresponding simulation results show that a better modeling is achieved using NF technique, especially that we did not employ any involved optimization procedure to identify the NF structure.

Keywords: Yeast fermentation, fed-batch, takagi-sugeno model, levenberg-marquardt algorithm.

Received November, 28 2007; accepted April 24, 2008

 
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 Video Compression Using Multiwavelet and Multistage Vector Quantization

 Esakkirajan Sankaralingam1, Veerakumar Thangaraj2, Senthil Vijayamani3,
and Navaneethan Palaniswamy1
 1Department of Electrical and Electronics Engineering, PSG College of Technology, India
2Department of Electronics and Communication Engineering, PSG College of Technology, India
3Department of Electrical and Electronics Engineering Nasik, Mahindra and Mahindra, India

Abstract: This paper presents a new video coding technique using multiwavelet transform and multi-stage vector quantization. Three types of redundancies that are common in video sequence are spatial, temporal and psycho visual redundancies. In this work, the spatial redundancy in the video is minimized using multiwavelet transform. The transform coefficients are then quantized using multi-stage vector quantization scheme.   Motion estimation/ compensation reduce temporal redundancy by exploiting interpicture correlation. Kite cross diamond search is the block matching algorithm used for motion estimation. The objective is to develop low bit rate video coder with acceptable visual quality. The performance of the proposed method is compared with wavelet based video coder.

Keywords: Multiwavelet, multistage vector quantization, kites cross diamond search.

 Received November 30, 2007; accepted May 12, 2008

 
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Towards Reengineering Web Applications
 to Web Services

Bouchiha Djelloul, Malki Mimoun, and Mostefai Abd El Kader
EEDIS Laboratory, University of Sidi Bel Abbes, Algeria


Abstract: Web services technology and service-oriented architectures are rapidly developing and widely supported. However, it is fairly difficult for existing web applications to expose functionality as services in a service-oriented architecture, because when web applications were built, they served as monolithic systems. This paper describes a framework called WA2WS, which can be used for constructing web Services from existing web applications. This framework consists of two phases. First, an abstraction phase which consists in extracting UML conceptual schema from a web application using domain ontology. Second, an implementation phase which consists in generating the JAVA code of web service from the UML conceptual schema using mapping rules.

Keywords: Reengineering, web services, service-oriented architectures, web applications, ontology, UML.

 Received December 11, 2007; accepted April 9, 2008 

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Pruning Based Interestingness of Mined Classification Patterns

Ahmed Al-Hegami
Department of Computer Science, University of Sana'a, Yemen

Abstract: Classification is an important problem in data mining. Decision tree induction is one of the most common techniques that are applied to solve the classification problem. Many decision tree induction algorithms have been proposed based on different attribute selection and pruning strategies. Although the patterns induced by decision trees are easy to interpret and comprehend compare to the patterns induced by other classification algorithms, the constructed decision trees may contain hundreds or thousand of nodes which are difficult to comprehend and interpret by the user who examines the patterns. For this reasons, the question of an appropriate constructing and providing a good pruning criteria have long been a topic of considerable debate. The main objective of such criteria is to create a tree such that the classification accuracy, when used on unseen data, is maximized and the tree size is minimized. Usually, most of decision tree algorithms perform splitting criteria to construct a tree first, then, prune the tree to find an accurate, simple, and comprehensible tree. Even after pruning, the decision tree constructed may be extremely huge and may reflect patterns, which are not interesting from the user point of view. In many scenarios, users are only interested in obtaining patterns that are interesting; thus, users may require obtaining a simple, and interpretable, but only approximate decision tree much better than an accurate tree that involves a lot of details. In this paper, we proposed a pruning approach that captures the user subjectivity to discoverer interesting patterns. The approach computes the subjective interestingness and uses it as a pruning criterion to prune away uninteresting patterns. The proposed framework helps in reducing the size of the induced model and maintaining the model. One of the features of the proposed approach is to capture the user background knowledge, which is monotonically augmented. The experimental results are quite promising.

Keywords: Knowledge discovery in databases, data mining, decision tree, domain knowledge, interestingness, novelty measure.

Received December 9, 2007; accepted March 30, 2008

 
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VI-SDB: A Convivial Approach for
Description and Manipulation of
 Deductive and Stratified Databases

Amel Touzi
Faculty of Sciences of Tunis, Tunisia University, Tunisia

Abstract: Although deductive databases is based on a well established formalism, they didn't know the expected success. Their use was limited to the academic purpose. Indeed, the deductive database management systems are judged abstract, rare in commercial offers, and often expensive.  In among the abstract concepts of the deductive databases, we mention the case of the negation and its treatment by the stratification. In this paper, we propose a convivial approach that aims to make transparent theses concepts relatively abstracted and to permit a friendly usse of deductive databases and stratified database. This approach permits to simplify concepts, which always remain delicate for this type of databases users or designers, like (1) the definition of a deductive and/or stratified database (2) the study of the stratifiability, (3) the determination of the maximal stratification, (4) the incremental definition of strata and (5) the checking of integrity constraints. These operations become more delicate if the database is voluminous. The proposed system supports rules update and is not limited to facts updating as in known deductive systems. This approach is implemented and validated with VI_SDB tool based on an extension of predicates nets.

Keywords: Deductive database, stratified database, EPN formalism, GUI.

Received March 18, 2007; accepted May 30, 2007

 
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Architectural Framework for Immersive
Web Based Virtual Environments

Nuha El-Khalili
Faculty of Information Technology, University of Petra, Jordan

Abstract: The development of 3D web based applications has been possible with the establishment of a number of 3D web technologies. Such applications have been utilized in different disciplines such as surgery planning, architectural design and games. However, most of these applications are trapped to the desktop setting provided by default in 3D technologies. Very few attempts have been made to present 3D immersive web based applications and to evaluate the usability of the technologies used and the interaction techniques. In this paper, we will attempt to address these questions by examining different ways of providing an immersive virtual environment on the web.

Keywords: 3D Web applications, VRML, Java 3D, immersive virtual environments.

 Received September 6, 2006; accepted April 20, 2008

 
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Proposed Enhancement of IEEE802.11e WLAN Through Real Time Simulation Study

Bahi Hour and Shihab Hameed
Faculty of Engineering, International Islamic University, Malaysia

Abstract: One of the most successful WLAN protocols is IEEE 802.11. That is due to the simplicity and robustness against failures of its medium access control protocol. In addition, IEEE introduces the standard 802.11e for quality of service support. However, this standard is not considered efficient when used for some applications that don’t involve data and background in the transmission, but only voice and video. Some of these applications are video conferencing and internal organizations’ voice over internet protocols calls. For the purpose of enhancing voice over internet protocols and video streaming over IEEE802.11e WLAN, we have developed an ns-2 patch in C++ which suites our requirements in a simulation based performance enhancement. In this paper, the performance of IEEE802.11e WLAN is evaluated and discussed based on simulation study using the network simulator (ns-2.29) under Linux operating systems fedora core 4. Our simulation results showed enhanced performance for the voice and video traffics over the original IEEE802.11e standard. This shows the effectiveness and efficiency of our simulator of enhancing the performance for voice and video based applications such as video conferencing and voice over internet protocols.

Keywords: IEEE 802.11e, medium access control, quality of service, hybrid coordination function controlled channel access, enhanced distributed channel access, coordination function.

 Received December 17, 2007; accepted April 22, 2008

 
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A Hybrid Protocol for Identification of a
 Maximal Set of Node Disjoint Paths in
Mobile Ad hoc Networks

Ash Abbas
 Department of Computer Engineering, Aligarh Muslim University, India


Abstract: Identifying a maximal set of node-disjoint paths between a given source and a destination is a challenging task in mobile ad hoc networks. One cannot guarantee to identify the maximal set of node-disjoint paths in a single sequence of request-reply cycle. However, one can guarantee to identify a maximal set of node-disjoint paths in an incremental fashion using multiple route discoveries. In this paper, we present a protocol that adopts an approach that is a hybrid of the approaches taken by a protocol that tries to identify multiple node-disjoint paths in a single go and a protocol that identifies them incrementally. Our approach preserves the guarantee to discover a maximal set of node-disjoint paths between a given source and a destination. Further, we have shown that our approach is scalable and it requires less number of route discoveries than that required by an incremental protocol.

Keywords: Ad hoc networks, path diminution, maximal set, node-disjoint, multipath routing, multiple route discoveries, incremental protocols.

Received April 6, 2007; accepted April 3, 2008 

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