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The Priority of Rules and the Termination Analysis Using Petri Nets

 Latifa Baba-hamed1 and Hafida Belbachir2

1Computer Science Department, University of Oran Es-Sénia, Algeria

2Computer Science Department, University of USTO, Algeria 

Abstract: An active database system is a conventional database system extended with a facility for managing active rules (or triggers).  Rules in active database systems can be very difficult to program, due to the unstructured and unpredictable nature of rule processing. In this paper, we propose a method of termination analysis of rules in an active database system based on Petri nets. We consider here the model structure and the model execution of the approach.  

Keywords: Active database, ECA rules, termination rules, Petri nets, path, priority. 

Received December 4, 2005; accepted June 19, 2006
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A Framework to Build Quality Models for Web Applications

Alessandro Marchetto and Andrea Trentini

 Dipartimento di Informatica e Comunicazione, Università degli Studi di Milano, Italy 

Abstract: This paper describes an approach to build and apply a quality model useful to analyze a web application through an object-oriented model and to evaluate the structural software qualities using the built model. The constructed quality model is focused on a set of software metrics and uses a prediction system based on software analogies analysis. In particular, the paper focuses on model construction, customization and interpretation. The proposed approach uses a combination of traditional web and object-oriented metrics to describe structural properties of web applications and to analyze them. These metrics are useful to measure some important software attributes such as complexity, coupling, size, cohesion and defects density. Furthermore, the presented quality model uses these metrics to describe applications in order to predict some software quality factors (such as test effort, reliability, error proneness) through an instance-based classification system. The approach uses a classification system to study software analogies and to define a set of information usable as the basis for applications quality factors prediction and evaluation. 

Keywords: Software metrics, test effort, quality factors prediction, classification systems. 

Received November 28, 2005; accepted April 13, 2006 
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Experiments of Intelligent Algorithms on Ramsey Graphs


Jihad Mohamad AlJaam

Department of Computer Science and Engineering, Qatar University, Qatar

Abstract: Ramsey numbers are known to be hard combinatorial problems that have many important applications including number theory, algebra, geometry, topology, set theory, logic, ergodic theory, information theory, and theoretical computer science.  The evaluation of Ramsey numbers using intelligent algorithms has been extensively studied in the last decades and only few numbers are currently known. Almost all of these methods failed to find the exact value of Ramsey numbers as they are over constraints problem. They have succeeded only to improve some upper and lower bounds of these numbers. In this work, we have tested the following intelligent algorithm: Backtracking, local search, tabu search and simulated annealing on some extremely hard instances of Ramsey numbers namely R (5, 9) - 120 and R (6, 8) - 121. As we failed to solve these hard instances using the previous techniques, we decided to combine them together in a hybrid metaheuristic algorithm and succeeded to generate the expected solutions. This new hybrid algorithm seems efficient and promising. It can be applied also on different combinatorial problems even if deep mathematical properties of the problems' domain are not on hand.

Keywords: Metaheuristic, hybrid algorithms, optimization, combinatorics, Ramsey numbers. 

Received November 19, 2005; accepted April 5, 2006
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Performance Analysis of Mobile IPv4 and Mobile IPv6

Fayza Nada

Faculty of Computers and information, Suez Canal University, Egypt 

Abstract: The number of mobile computers is increasing at a phenomenal rate, and efficient support for mobility will make a decisive difference to the Internet's future performance. This, along with the growing importance of the Internet and the web indicates the need to pay attention to supporting mobility. Mobile IPv6 (MIPv6) is a protocol to deal with mobility for the next generation Internet (IPv6). However, the performance of MIPv6, especially in comparison with MIPv4, has not been extensively investigated yet.  In this paper, we present an analysis of the Mobile IPv6 performance as the packets delay changes due to supporting mobility. We also introduce a comparison between Mobile IPv4 and Mobile IPv6 in supporting mobility. 

Keywords: MIPv4, MIPv6, mobile networking, TCP performance, network simulation. 

Received November 18, 2005; accepted March 4, 2006
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An Efficient Parallel Gauss-Seidel Algorithm for the Solution of Load Flow Problems

Raed Alqadi1 and Maher Khammash2

1Department of Computer Engineering, An-Najah National University, Palestine

2Department of Electrical Engineering, An-Najah National University, Palestine

 Abstract: In this paper, a parallel algorithm for solving the load flow problem of large power systems is presented. This algorithm uses a parallel virtual machine implemented as a distributed system built from readily available PCs. The proposed algorithm is based on the Gauss-Seidel algorithm usually used in the solution of load flow problems. This algorithm is parallelized by distributing the bus voltages among a set of processors such that each processor will be working on 1/n of the bus voltages in the circuit, where n is the number of processors. Since it is virtually impossible to obtain a parallel processing machine in our country, the algorithm is developed over a distributed system which consists of a network of PCs. Even though the communication overhead is much more than that in a real parallel machine, the results show that large power systems can be solved in much less time compared to the time required for sequential algorithm usually used, and that with proper selection of the number of processors, the execution time is reduced by almost a factor of the number of processors.  

Keywords: Parallel algorithm, distributed system, load flow, communication overhead, execution time. 

Received November 16, 2005; accepted April 22, 2006
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A Framework for Evaluating and Selecting Learning Technologies

Abdel Nasser Zaied

College of Graduate Studies, Arabian Gulf University, Bahrain

 Abstract: This paper considers some of the major issues in the field of learning technology selection. It presents a framework towards the development of selection criteria that aim at improving technology selection process to avoid the technological problems. The variables like gender, age, and race of the participants are not examined. To find out the criteria, which have high impact on learning technology selection, three groups (faculties, IT specialists & students) and two control groups (faculties working as IT specialists & students working as IT specialists) are selected from three Gulf universities (Arabian Gulf University, Bahrain University and Kuwait University). Initially, 19 criteria are used; the groups’ independent opinion is collected for analysis and organized according to the weighted average. The top criteria (over mean) are retained and the others are canceled. Seven criteria show high impact on learning technology selection process in general. These criteria are feedback capability, student/instructor satisfaction, student motivation and self-learning, ease of access, use and revision, professional development, usability and reliability and instructional time.

Keyword: Learning technology, technology selection criteria. 


Received October 31, 2005; accepted March 4, 2006
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Numerical Solution of One GSM Cell Using

MOSEL-2 Language

Aymen Zreikat

Department of Information Technology, Mu’tah University, Jordan 

Abstract: This paper presents a numerical solution of one GSM cell using the Modeling Specification and Evaluation Language (MOSEL-2) which is the new version of MOSEL, developed at the University of Erlangen, Germany. In this regard, the frequency spectrum of GSM cell is divided into two layers (super and regular) according to the intelligent underlay-overlay principle. Based on this principle, the super frequencies have better Carrier-to-Interference (C/I) ratio than the regular frequencies and usually used near the base station in hot spot areas, while the regular frequencies are used for the whole cell. In this paper, and based on the above assumptions, the queuing model of GSM systems is suggested and the numerical solution of this model is presented by MOSEL-2. As a result of this, the critical performance measures such as: loss probability, mean queue length and utilization are presented and discussed.

Keywords: Performance modelling, GSM systems, MOSEL-2, underlay-overlay, performance measures, queuing model. 

Received October 27, 2005; accepted January 22, 2006
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Arabic Text Categorization

Rehab Duwairi

Department of Computer Information Systems, Jordan University of Science and Technology, Jordan

 Abstract: In this paper, we compare the performance of three classifiers for Arabic text categorization. In particular, the naïve Bayes, k-nearest-neighbors (knn), and distance-based classifiers were used. Unclassified documents were preprocessed by removing punctuation marks and stopwords. Each document is then represented as a vector of words (or of words and their frequencies as in the case of the naïve Bayes classifier). Stemming was used to reduce the dimensionality of feature vectors of documents. The accuracy of the classifiers is compared using recall, precision, error rate and fallout. The results of the experimentations that were carried out on an in-house collected Arabic text show that the naïve Bayes classifier outperforms the other two.  

Keywords: Text categorization, naïve Bayes, knn, distance-based classifier, Arabic language. 

Received October 10, 2005; accepted March 1, 2006
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Enhanced Dynamic Bandwidth Allocation Proportional to Queue Length with Threshold Value for VBR Traffic

Wee Kuokkwee, Mohamed Othman, Subramaniam Shamala, and Ahmad Ariffin

Department of Communication Technology and Network, University Putra Malaysia, Malaysia

 Abstract: In Asynchronous Transfer Mode (ATM) network, Variable Bit Rate (VBR) service category has been defined to support any application for which the end-system can benefit from statistical multiplexing, by sending information at a variable rate, and can tolerate or recover from a potentially small random loss ratio. Due to its burst characteristic, bandwidth allocation strategy is necessary in order to share the network resources with other traffics fairly. The implementation of proposed approaches; heuristic, Unused Buffer Reallocation (UnBR) and Higher-priority Queue Sharing (HQS), in bandwidth strategy perform better improvement if compare to the proposed strategy. In addition, we observed that a bandwidth strategy did not always perform well, hence, suitable strategies should be chosen depending on the different conditions in order to fulfill its network demand. 

Keywords:  Bandwidth allocation, VBR, heuristic approach.

Received October 7, 2005; accepted April 10, 2006
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An Extended Feature Modelling Based Component Model for Performance Evaluation

Zhongjie Wang, Xiaofei Xu, and Dechen Zhan

School of Computer Science and Technology, Harbin Institute of Technology, China 

Abstract: Traditional component modelling methods focus emphatically on the precise and formal descriptions of business semantics, while usually cannot support to conveniently evaluate the reuse performance of components. Our main concern is to present a new component model for measuring performance after components being designed and before practically reused. The proposed model uses the Extended Feature Modelling method (Ext-FM) to express business semantics and uses variation point to express component¢s reuse mechanism. Some example metrics for component reusability are addressed briefly to validate the effectiveness of this model. 

Keywords: Component model, extended feature modelling, variation point, reusability metrics. 

Received August 28, 2005; accepted April 13, 2006
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SD-SQL Server: Scalable Distributed Database System

Soror Sahri

CERIA, Université Paris Dauphine, France

 Abstract: We present SD-SQL Server, a prototype scalable distributed database system. It let a relational table to grow over new storage nodes invisibly to the application. The evolution uses splits dynamically generating a distributed range partitioning of the table. The splits avoid the reorganization of a growing database, necessary for the current DBMSs and a headache for the administrators. We illustrate the architecture of our system, its capabilities and performance. The experiments with the well-known SkyServer database show that the overhead of the scalable distributed table management is typically minimal. To our best knowledge, SD-SQL Server is the only DBMS with the discussed capabilities at present. 

Keywords: Scalable distributed DBS, scalable table, distributed partitioned view, SDDS, performance. 

Received June 4, 2005; accepted June 27, 2006
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Intelligent Agent Based Approach for Transaction Processing in Mobile Database Systems

Sekar Ganesh, Mathan Vijayalakshmi, and Arputharaj Kannan

Department of Computer Science and Engineering, College of Engineering, Anna University, India 

Abstract: Transaction processing in a Mobile Database System (MDS) is more complex because of unlimited mobility of the Mobile Unit (MU). The handoff and frequent failure of mobile unit makes it tricky to store log records and access it for recovery. In this paper, we present a new log management scheme, which uses a mobile-agent-based framework to facilitate efficient transaction processing during handoff or MU failure. Instead of executing the transaction in mobile unit, we are giving it to base agent which is in the base station. By doing so, we save power in the mobile unit. Moreover, we are using announcement scheme during handoff which minimizes traffic of Home Location Register Database. Also we use Speculative Locking (SL) protocol, which improves the performance of fixed network transaction by trading extra processing power. In SL, a transaction releases the lock on the data object whenever it produces corresponding after-image during its execution. By accessing both before image and after images, the waiting transaction carries out speculative execution retains one execution based on the termination (commit or abort) mode of the preceding transactions.  We have also compared waiting time of ordinary locking protocol and speculative locking protocol. 

Keywords: Mobile databases, mobile agents, locking protocols. 

Received May 24, 2005; accepted April 12, 2006
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The Development of a Simplified Process Model

for CBSD

Hazleen Aris1 and Siti Salwah Salim2

1College of Information Technology, Universiti Tenaga Nasional, Malaysia

2Faculty of Computer Science and Information Technology, University of Malaya, Malaysia


Abstract: This study introduces the MyCL process model, a simplified Component-Based Software Development (CBSD) process model that is clear and easy to be understood and hence, applied. It is motivated by the fact that even though many CBSD process models have been proposed, a clear and step-by-step guidance is still lacking. They vary from one another and some are even complicated and difficult to be applied.  The MyCL process model is therefore derived by retaining the strengths and overcoming the impracticality causes of these existing CBSD process models. Evaluation of the model, which was carried out by interviewing the experts in this field has shown that this model has a good potential to be applied by software developers, especially those who are new to CBSD.

 Keywords: Software methodology, component-based software development, software engineering, process model. 

Received April 6, 2005; accepted June 30, 2006

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