The International Arab Journal of 

Information Technology

 

January 2006, Volume 3, Number 1

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A Mobility-Aware Two-Phase Commit Protocol

 

Nadia Nouali1&2, Habiba Drias2, and Anne Doucet3

1Mobile Computing Department, CERIST, Algeria

2Faculté du Génie Electrique, Université Houari Boumediene, Algeria

3LIP6 Laboratory, Université Pierre et Marie Curie, France

 

Abstract: Mobile computing is increasingly attracting attention of researchers to revisit the conventional implementation of distributed computing paradigms for use in this new environment. In this paper we propose to revisit the conventional implementation of the Two Phase Commit (2PC) protocol which is a fundamental asset of transactional technology for ensuring consistent effects of distributed transactions. We propose a new execution framework to provide an efficient extension that is aware of the mobility of the mobile host. The proposed M-2PC (Mobility-aware 2PC protocol preserves the 2PC principle and the freedom of the mobile clients and servers while it minimizes the impact of wireless and unreliable.

Keywords: Mobile 2PC protocol, Mobile Transactions, Mobile computing, Disconnection, Mobility.

Received March 15, 2004; accepted October 30, 2004

 

A Novel Quantum-Inspired Evaluation Algorithm for Multi-Source Affine Image Registration

 

1Hichem Talbi, 2Amer Draa, 3Mohamed Batouche

 1USI Emir Abdelkader, Constantine, Algeria

2,3Lire Laboratory, Mentouri University, Constantine, Algeria

 

Abstract: In this paper we propose a new algorithm for image registration which is a key stage in almost every computer vision system. The algorithm is inspired from both genetic algorithms and quantum computing fields and uses the mutual information as a measure of similarity. The proposed approach is based on some concepts and principles of quantum computing such as quantum bit and states superposition. So, the definitions of the basic genetic operations have been adapted to use the new concepts. The evaluation of each solution is performed by the computation of mutual information between the reference image and the resulting image. The process aims to maximize this mutual information in order to get the best affine transformation parameters which allow the alignment of the two images.

Keywords: Image registration, genetic algorithms, mutual information, quantum computation, states’ superposition

Received August 5, 2004; accepted November 3, 2004

 

 

Incremental Learning of Auto-Association Multilayer Perceptrons Network

   

Essam Al -Daoud

Jordan, Zarka Private University, Faculty of Science,

Computer Science Department

 

 

Abstract: This paper introduces a new algorithm to reduce the time of updating the weights of auto-association multilayer perceptrons network. The basic idea is to modify the singular value decomposition which has been used in the batch algorithm to update the weights whenever a new row is added to the input matrix. The computation analysis and the experiments show that the new algorithm speeds up the implementation about 5-8 times.  

 

Keywords: Neural Networks, Auto-Association Multilayer Perceptrons, Singular Value Decomposition

Received October 10, 2004; accepted December 16, 2004

 

 

Design and Implementaion of A Two-Phase Commit Protocol Simulator

 

T. Taibi1, A. Abid2, W.J. Lim2, Y.F. Chiam2, C.T. Ng2

1College of Information Technology

 United Arab Emirates University

 2Faculty of Information Technology
Multimedia University

Selangor, Malaysia

 

 

Abstract: The world of computing is moving towards a trend where tasks are being done in a distributed manner. This is especially relevant in distributed transaction processing systems used by financial institutions, where a single transaction could result in significant changes in other parts of the system. In a distributed system, a transaction often involves the participation of multiple sites and access of shared data in remote locations. A failure of one site in committing its part of the transaction could cause the entire system to be inconsistent. Thus, some form of control is necessary to ensure that concurrent execution of transactions in a distributed environment does not jeopardize the integrity of the system as well as its data consistency. In this work a Two-Phase Commit Protocol (2PC) simulator was developed using Java Remote Method Invocation (RMI) in order to visualize and monitor the execution of transactions and their failure and recovery.

 

Keywords: 2PC, Transaction Coordinator, Transaction Manager, Data Manager, Locking Manager, Failure Recovery, Java RMI.

Received July 9, 2004; accepted December 17, 2004

05

 

Speaker Recognition for Wire/Wireless Communication Systems

Mohamed Abdel Fattah, Fuji Ren, and Shingo Kuroiwa

Faculty of Engineering, The University of Tokushima, Japan

 

 Abstract: Recently data communication spread to the mobile wireless world. The complexity of medium and large speech & speaker recognition systems are beyond the memory and computational resources of the small portable devices. Moreover the most common approach to speaker recognition today is the use of global Gaussian mixture models (GMM) which ignores knowledge of the underlying phonetic content of the speech, so it does not take advantage of all available information. In this paper we address the solution of these two problems by investigating the phoneme effect on speaker recognition system. We used YOHO database for speaker identification task. We found that some phonemes have strong effect on speaker identification. Segmenting the most effective phoneme for speaker recognition task from a speaker utterance and send this phoneme only through the wireless communication system will decrease the complexity of medium and speed up the authentication process though mobile communication system. We have applied different approaches   on YOHO corpus, several of these approaches were able outperform previously published results on the speaker ID task. One of our approaches could achieve 0.7% error rate by using only an average segment of 4.45% of the testing utterance for recognition.

Keywords: Speaker recognition, speaker identification, speech recognition, wireless communications

Received August 24, 2004; accepted September 17, 2004 

 

 

 

 A New Approach in Key Generation and Expansion in Rijndael Algorithm

 

Naim Ajlouni1, Asim El-Sheikh2, and Abdullah Abdali Rashed2

1Amman Arab University for Graduate Studies, Jordan

2Arab Academy for Banking and Financial Science, Jordan

 

Abstract: This paper presents a new algorithm that simplifies the process of generating and expanding cipher key, which is considered one of the most important elements in ciphering process. This algorithm generates a pool of keys, and then sends this pool to the authorized receiver. Sender will use this pool to select the schedule key randomly. In key exchange, receiver will get the index of the first element in the schedule key at the other and the algorithm extracts the schedule key and uses it to decipher the ciphered block without key re-expansion.

 Keywords: Rijndael block cipher, AES, key generation, key expansion.

Received September 1, 2004; accepted December 21, 2004

 

 

 

Incremental Genetic Algorithm

 

Nashat Mansour1, Mohamad Awad1, and Khaled El-Fakih2

1Computer Science Division, Lebanese American University, Lebanon

2Department of Computer Science, American University of Sharjah, UAE

 

Abstract: Classical genetic algorithms (CGA) are known to find good sub-optimal solutions for complex and intractable optimization problems. In many cases, problems undergo frequent minor modifications, each producing a new problem version. If these problems are not small in size, it becomes costly to use a genetic algorithm to reoptimize them after each modification. In this paper, we propose an Incremental Genetic Algorithm (IGA) to reduce the time needed to reoptimize modified problems.The idea of IGA is simple and leads to useful results. IGA is similar to CGA except that it starts with an initial population that contains chromosomes saved from the CGA run for the initial problem version (prior to modifying it). These chromosomes are best feasible and best infeasible chromosomes to which we apply two techniques in order to ensure sufficient diversity within them. To validate the proposed approach, we consider three problems: optimal regression software testing, general optimization, and exam scheduling. The empirical results obtained by applying IGA to the three optimization problems show that IGA requires a smaller number of generations than those of a CGA to find a solution. In addition, the quality of the solutions produced by IGA is comparable to those of CGA.

Keywords: Exam scheduling, general optimization, incremental genetic algorithms, optimization algorithms, regression testing, soft computing.

Received September 28, 2004; accepted December 21, 2004

 

 

 

A Virtual Cooperative Learning Environment Using Human Companion

 

Tahar Bouhadada and Mohamed Tayeb Laskri

Research Group on Artificial Intelligence, University of Annaba, Algeria

 

Abstract: This paper describes the architecture of an interactive learning environment (ILE) on Internet using companions which one is a human and geographically distant of the learning site. The achieved system rests on a three-tier Customer/Server architecture (Customer, Web Server, Data and applications Server) where human and software actors can communicate via the Internet. and uses the DTL learning strategy. It contents five main actors: a tutor actor in charge to guide the learner; a system actor whose role is to manage and to control the accesses to the system; a teacher actor in charge of the management and the updating of the different bases; a llearner actor who represents the main actor of the system for whom is dedicated the teaching. And a learning companion actor whose role can be sometimes as an assistant, and other times, as a troublemaker.

Keywords: Interactive learning environment, LCS, DTL strategy, companion, distant learning, troublemaker.

Received July 20, 2004; accepted September 26, 2004

 

 

 

Integrating Multicasting and Hash Algorithm to support Host Mobility

 

Sahar Al-Talib, Borhanuddin Mohd Ali, and Sabira Khatun

Department of Communication and Networking System, Universiti Putra Malaysia, Malaysia

 

Abstract: The paper explains a framework that has been proposed to construct a dynamic delivery tree for the mobile node (MN) movement in a mobile IPv6 network. The branches of the tree constitute the shortest paths from the packet source to each of the visited locations. The tree is dynamic such that the branches grow and shrink to reach the MN when necessary. This architecture is multicast-based, in which a mobile node is assigned a multicast address and the correspondent nodes send packets to that multicast group. As the mobile node moves to a new location, it joins the multicast group through the new location and prunes through the old location. Hash Algorithm has been implemented as a mechanism for the MN to join and leave a multicast group. Dynamics of the multicast tree provide for smooth handoff, efficient routing and conservation of network bandwidth. To allow a smooth handoff, the MN should not prune the old location until it starts receiving packets from the new location. The performance of the proposed mechanism was evaluated through a simulation model built for this purpose. The simulation results showed that the dynamics of joining and leaving the group directly affect handoff latency and smoothness, as a result it conserved radio frequency (RF) bandwidth.

 Keywords: Mobile IPv6, multicast group, hash algorithm, handover.

Received July 27, 2004; accepted December 28, 2004

 

 

 

MOSIX Evaluation on a Linux Cluster

 

Najib Kofahi1, Saeed Al Zahrani2, and Syed Manzoor Hussain3

1Department of Computer Sciences, Yarmouk University, Jordan

2Saudi Aramco, SA

3Dept. of Information and Computer Science, King Fahd University of Petroleum and Minerals, SA

 

Abstract: MOSIX (Multicomputer Operating System for Unix) is a cluster-computing enhancement of Linux kernel that supports preemptive process migration. It consists of adaptive resource sharing algorithms for high performance scalability by migrating processes across a cluster. MPI (Message Passing Interface) is a library standard for writing message passing programs, which has the advantage of portability and ease of use. This paper highlights the advantages of a process migration model to utilize computing resources better and gain considerable speedups in the execution of parallel and multi-tasking applications. We executed several CPU bound tests under MPI and MOSIX. The results of these tests show the advantage of using MOSIX over MPI. At the end of this paper, we present the performance of the executions of those tests, which showed that in some cases improvement in the performance of MOSIX over MPI can reach tens of percents.

Keywords: High performance computing, performance evaluation, Linux cluster, MOSIX, MPI, process migration.

Received July 28, 2004; accepted September 30, 2004

 

Image Segmentation and Edge Detection Based on Chan-Vese Algorithm

 

Nassir Salman

Computer Science Department, Zarqa Private University, Jordan

 

Abstract: The main idea in this paper is to detect regions(objects) and their boundaries, also to isolate and extract individual components from a medical image. This can be done using K-means firstly to detect regions in a given image. Then based on techniques of curve evolution, Chan-Vese for segmentation and level sets approaches to detect the edges around each selected region. Once we classified our images into different intensity regions based on K-means method, to be easy to separate each region with its boundary and its area individually in the next steps . Then we detect regions whose boundaries are not necessarily defined by gradient using Chan-Vese algorithm for segmentation. In the level set formulation, the problem becomes a mean-curvature flow like evolving the active contour, which will stop on the desired boundary of our selected region results from K- means step. The final image segmentation results are one closed boundary per actual region in the image and segmented map

Keywords: Chan-Vese approach , K-means, Active counters, Level set methods, Segmentation , Edge detection,

Received September 30, 2004; accepted February 1, 2005

 

An Extended E-Learning Architecture: Integrating Software Tools Within The E-Learning Portal

 

Zuhoor Al-Khanjari, Swamy Kutti, and Muna Hatem 

Department of Computer Science, Sultan Qaboos University, Sultanate of Oman

 

Abstract: Higher education based on the Information Technology is found to be a feasible and economical model in improving the traditional education model [1, 2]. Consequently e-Learning portals have been used to design online courses according to the course goals and students needs. A basic goal of on-line course design is to provide almost a complete course environment including a virtual lab related to each course if needed. This allows students to access the entire course environment in on-line at anytime, and from anywhere. This paper explains the development of a feasible system architecture that extends the services of a portal by integrating software tools as part of the designed on-line courses. The resulting architecture is simple, distributed resources and cost effective. The supporting experimental work has been carried out on the test bed around the e-Learning portal WebCT that is currently available in SQU (Sultan Qaboos University).

Keywords: E-Learning, e-Learning Portal, Internet Training, Workgroup Learning, Web-server, MyCoursesServer, Application server, Unix Network Server, WebCT.

Received June 13, 2004; accepted February 25, 2005

 

Partial Automation of Sensitivity Analysis by Mutant Schemata Approach

 

Zuhoor Al-Khanjari

Department of Computer Science, Sultan Qaboos University, Oman

 

Abstract: According to Voas et al. testability is defined as the ease with which faults may manifest themselves as failures when the software undergoes the testing process [1]. They also went further by introducing an approach for measuring sensitivity in terms of estimates from Propagation, Infection and Execution (PIE) analyses of software and calculating the testability of a program through sensitivity estimate. Their testability calculations ‘by hand’ to determine the stability of the PIE analysis technique had drawbacks such as more time-consuming, high cost and less precision in the overall results [2]. Particularly the infection analysis part is one of the most expensive, sophisticated and time-consuming component of the PIE analysis technique. In order to solve this problem an investigation has been carried out by the author for establishing the feasibility of automating (or partially automating) the PIE analysis technique by means of a fast, and computationally less expensive approach [3]. A Mutant Schemata Generation Infection (MSG-Infection) tool has been developed to automate PIE analyses partially. This paper introduces the MSG-Infection tool briefly and explains the method of automating the PIE analyses technique. It also presents the results indicating a significant improvement in performance due to MSG-Infection tool.

Keywords: testability analysis, sensitivity analysis, PIE technique, mutation testing, mutant schemata approach, Mothra Mutation system, PiSCES software, MSG-Infection tool, system time, user time and real time.

Received June 20, 2004; accepted February 2, 2005