Volume 5, Number 1, December 2007


Computing and Information Sciences is a peer reviewed journal that is committed to timely publication of original research, surveying and tutorial contributions on the analysis and development of computing and information science. The journal is designed mainly to serve researchers and developers, dealing with information and computing. Papers that can provide both theoretical analysis, along with carefully designed computational experiments, are particularly welcome. The journal is published 2-3 times per year with distribution to librarians, universities, research centers, researchers in computing, mathematics, and information science. The journal maintains strict refereeing procedures through its editorial policies in order to publish papers of only the highest quality. The refereeing is done by anonymous Reviewers. Often, reviews take four months to six months to obtain, occasionally longer, and it takes an additional several months for the publication process.

Paper 1: Practical Efficiencies of Slotted Stream Tapping in IP Networks

Practical Efficiencies of Slotted Stream Tapping in IP Networks

Achraf Gazdar and Abdelfettah Belghith

Abstract: Many broadcasting protocols have been proposed for video-on-demand systems. The overwhelming majority of these protocols are, however, analytically evaluated or studied through simulations but virtually with no consideration to their feasibility and or ease of implementation in a real network environment. Efficient VoD protocols are usually the most complex in terms of implementation at both the client and the server sides. In this paper, we detail the design and the implementation of our proposed VoD protocol called Slotted Stream Tapping (SST), in an IP environment using IETF standards. We compare STT results to the theoretical results of the most known hybrid protocols and show that SST presents indeed an adequate compromise between ease of implementation and server/network performance. Extensive experiments are conducted on our test bed to evaluate the server/client bandwidth consumption and the client buffer size. We finally compare STT theoretical and experimental results which we prove to be in very close resemblance.



Paper 2: Enhancing PSM Efficiencies in Infrastructure 802.11 Networks

Enhancing PSM Efficiencies in Infrastructure 802.11 Networks

Abdelfettah Belghith, Aymen Belghith and Miklos Molnar

Abstract:Power conservation techniques are of utmost importance in Wireless LANs to prolong the life of mobile stations relying on portable limited energy batteries. A power conservation mechanism should provide the maximum energy saving at light traffic loads, yet thrives to deliver data as much as possible in high traffic conditions. In this paper, we investigate the inherent functional properties of the infrastructure mode IEEE 802.11 Power Saving Mechanism (PSM). We show through extensive simulations that PSM stands very short and does not level up to its design objectives. PSM blocks the network traffic flow, yet it does not adequately save energy as supposed to be. We show that at high traffic loads, PSM exhibits a very poor throughput and excessive power consumption per delivered data frame. We therefore investigate the inherent properties that made PSM inefficient and propose two different enhancements called State Aware PSM (SA-PSM) and Once Poll PSM (OP-PSM). We show through extensive simulations that tangible improvements are attained. These enhancements save power as much as PSM for light traffic loads and deliver as much a throughput as when no power saving mechanism is deployed. Virtually at all traffic loads, OP-PSM and SA-PSM nicely outperform PSM and provide a much less average time spent by a data frame from its generation at the source station until its delivery to the destination station.



Paper 3: A Distributed Clustering Algorithm without an Explicit Neighbourhood  Knowledge

A Distributed Clustering Algorithm without an Explicit Neighbourhood  Knowledge

Abdelfettah Belghith, Imen Jemili and Mohamed Mosbah

Abstract: Ad-hoc networks have received significant attention over the last few years as these emerging networks provide a fast deployable multi-hop wireless infrastructure for a growing number of applications when a wireline network is neither available nor economical to build. To overcome the scalability problem, creating hierarchies among the nodes seems to be a promising approach and an effective way to organize the network as the number of nodes increases. In this paper, we present a novel distributed clustering algorithm for ad-hoc networks. Our algorithm is based on a synchronized and layered process. Its main objective is to minimize the number of control messages exchanged during the clustering process. We evaluate our algorithm using the Visidia simulation test bed and show that it outperforms one of the most known clustering algorithms in minimizing both the number of control messages and the number of elected clusterheads.



Paper 4: From Formal Specification to Model Checking of MAS Using CSP-Z and SPIN

From Formal Specification to Model Checking of MAS Using CSP-Z and SPIN

Ahmed Hadj Kacem and Najla Hadj Kacem

Abstract: As a result of the increasingly predominance of agent technology, there has been a lot of interest in developing agent-based methodologies. In particular, formal methodologies have recently received the attention of the agent community. One of the key features of these methodologies is their emphasis on the use of formal methods as a means to trust multiagent systems (MAS) to behave as expected. The main purpose of this paper is to extend the development process of a formal approach for designing agent-based applications, called ForMAAD. The effort expended in the added phase is concentrated on two tasks: formally specify MAS to provide a more concrete specification, and verify that the specified system fulfils correctness properties. The adoption of formal techniques from the concurrency theory is founded on the view of MAS as a computational organization of concurrent problem-solving entities.




Paper 5: Considering Topological Constraints for the Description of Dynamic Service- ...

Considering Topological Constraints for the Description of Dynamic Service-Oriented Orchestrated Architecture

Karim Guennoun, Khalil Drira and Michel Diaz

Abstract: The description of run-time changing architectures cannot be limited to the specification of a unique static topology but must cover the scope of all the correct configurations. We develop, in this paper, the concept of architectural styles to achieve this goal. We elaborate and specify the basic architectural styles for the de-sign of service-oriented applications. For this purpose we develop an appropriate formal framework using graph grammars. Our approach enables both generating architectures in conformance with a breitling replica sale style and checking conformance of ad-hoc architectures. We first, describe formally the basic interaction style involving the orchestrated interaction model where an orchestrator manages the workflow of several service requestors and providers. Finally, we define a complex architectural style to address hierarchical orchestration.



Paper 6: Workflow Soundness Verification Based on Structure Theory of Petri Nets

Workflow Soundness Verification Based on Structure Theory of Petri Nets

Kamel Barkaoui, Rahma Ben Ayed and Zohra Sbaï

Abstract: Modern workflow management systems have to support tasks with complex dependency constraints and to cope with resource allocation problem. Therefore the need for analysis method to verify the correctness of workflow specification is becoming crucial. This paper exploits recent advances of structure theory of Petri nets to find efficient structural characterization of the basic soundness property. The obtained results allow the identification and analysis of workflow net classes allowing the modelling of complex synchronization and routing workflow constructs of practical need in particular in the context of collaborative management systems.



Paper 7: Lip Localization and Viseme Classification for Visual Speech Recognition

Lip Localization and Viseme Classification for Visual Speech Recognition

Salah Werda, Walid Mahdi and Abdelmajid Ben Hamadou

Abstract: The need for an automatic lip-reading system is ever increasing. In fact, today, extraction and reliable analysis of facial movements make up an important part in many multimedia systems such as videoconference, low communication systems, lip-reading systems. In addition, visual information is imperative among people with special needs. We can imagine, for example, a dependent person ordering a machine with an easy lip movement or by a simple syllable pronunciation. Moreover, people with hearing problems compensate for their special needs by lip-reading as well as listening to the person with whom they are talking. We present in this paper a new approach to automatically localize lip feature points in a speaker’s face and to carry out a spatial-temporal tracking of these points. The extracted visual information is then classified in order to recognize the uttered viseme (visual phoneme). We have developed our Automatic Lip Feature Extraction prototype (ALiFE). Experiments revealed that our system recognizes 72.73% of French Vowels uttered by multiple speakers (female and male) under natural conditions.



Prof. Jihad Mohamad Alja'am 
Email: journal.editor.ijcis@gmail.com

The Journal Secretary
Eng. Dana Bandok
Ontario, Canada 
Email: sec.ijcis@gmail.com 


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