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International Review on Computers and Software - September 2008 - Papers

New Methods of Image Analysis Applied to Hand-Written Arabic Character Recognition
Adaptive Multi-Channel SteganoGraphy in Bitmap Images
Stereo Image Reversible Watermarking
Per-Pixel Displacement Mapping Using Cone Tracing
Vertical Handover Evaluation for WiWi Network Based on Overall Throughput
A Model for Header Compression Context Transfer in Cellular IP
On Analysis of Boundness Property for ECATNets By Using Logic of Concurrency
A New Mobility Metric for Evaluating Ad Hoc Network Performance
An Adaptive Approach to Anomaly Intrusion Detection Based on Data Mining and String Metrics
A New Collaborative System for Industrial Tele-Maintenance
A Review on Genetic Algorithm in Parallel & Distributed Environment
A Simple DFE–Based Equalization Technique for Wideband Communications: System Design and Optimization Issues
A Hybrid Data Integration Approach Based on Specialized Mediators
Distributed Caml Light

International Review on Computers and Software - Papers

New Methods of Image Analysis Applied to Hand-Written Arabic Character Recognition
by F. Bouchareb, R. Hamdi

Abstract - This paper describes new methods for handwritten Arabic character recognition. We propose a novel algorithm for smoothing image and segmentation of the Arabic character using width writing estimated from skeleton character The moments and Fourier descriptor of profile projection and centered distance are used as features of each character, these features are invariant in translation , rotation and scale. We apply Principal component Analysis (PCA) as data processing algorithm to features vector in order to reduce dimension. The classifier proposed in this work is based on Support Vector Machines (SVM) which considered as a recent optimal classifier up to now. The results show that these methods are very powerful for isolated handwritten Arabic character.

Keywords: Arabic caracter recognitio; PCA; SVM; OCR.

Adaptive Multi-Channel SteganoGraphy in Bitmap Images

by G. Dastghaibyfard, M. A. Nikouei Mahani, S. Niktab Etaati

Abstract - In this paper a new method for steganography in bitmap and grayscale images is proposed. This method uses covert channels to hide the message. These covert channels defined on a specific color band. For hiding the message, at first message bytes split into nibbles, then the distance between pixels in the channel band, change and adjust according to message nibbles. It hides the message implicitly, instead of replacing redundant bits with message bits and improves the security and invisibility. The proposed method described in tree main part: 1- preparing message. 2- Stego Encoding. 3 - Stego Decoding, that each part are described precisely. The Peak Signal-to-Noise Ratio (PSNR) of affected images show low difference between original and affected image.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: SteganoGraphy, Multi-Channel, Bitmap, Covert Communication.

Stereo Image Reversible Watermarking
by J. N. Ellinas

Abstract - In this paper, a new reversible watermarking method is presented that reduces the size of a stereoscopic image pair while keeping its content visible. The proposed technique embeds the disparity compensated difference and the disparity vectors of the stereo pair into the reference image, halving its total capacity. The residual is usually lossy compressed before embedding because the embedding bit rate of the reference image is not high enough. The watermarked image is visible at a high quality and at any instant the stereo pair may be recovered by an inverse process. In fact, the reference image may be exactly recovered whereas the target image is slightly distorted as the residual is not embedded intact. The embedding capacity of the reference image and the quality of the watermarked image are contradictory and depend on the image content as well as the effectiveness of the embedding algorithm. The employed embedding method reorders the reference image into an array of consecutive pixel pairs and embeds a number of bits according to the intensity difference of each pair. In this way, it hides a number of bits in intensity smooth areas and most of the data in textured areas where resulting distortions are less visible. The effect of different traversal schemes on the performance of the embedding algorithm is also examined and an approximate method is suggested in order to select the most suitable scheme for embedding capacity enhancement.

Keywords: Reversible watermarking, Disparity compensation, Traversal schemes.

Per-Pixel Displacement Mapping Using Cone Tracing
by A. Halli, A. Saaidi, K. Satori, H. Tairi

Abstract - The technique of cone tracing, used for rendering very detailed surface in real-time, is certainly among the best techniques at the present time. But unfortunately, in its two versions, conservative and relaxed, this technique suffers from a heavy pre-processing having a quadratic complexity. Moreover, the processing of non-square textures remains a problem. In this article we introduce a new linear complexity algorithm for generating relaxed cone maps. Additionally, we propose to use the Height Distributional Distance Transform HDDT for creating conservative cone maps. The HDDT is a linear algorithm used in terrain rendering. We also introduce a new method for supporting non-square textures using an elliptical rectification. Finally, we suggest using the cones’ radius instead of their ratio. This eliminates the constraint limiting the cones’ apex angle to π/4 which significantly improves the performance of the cone tracing technique.

Keywords: Real time rendering, per-pixel displacement mapping, cone tracing.

Vertical Handover Evaluation for WiWi Network Based on Overall Throughput

by R. A. Saeed, H. Mohamad, B. M. Ali, M. Abbas

Abstract - The next generation wireless networks will consist of several overlapping tiers. Provision of undisrupted communication to mobile users is a challenging task. Handover delay is one of the problematic issues that users are face in the heterogynous networks. However, in the case of both WiMAX and WiFi technologies located at the same base station (BS); the vertical handover (VHO) delay will be less compared with two conventional WiMAX/WiFi heterogonous networks with two different wireless Internet service providers (WISP). However, protocol conversion is still adding delay and jitter for data exchange between the needed two technologies. In this paper, In order to reduce the delay in protocol conversion, a new design for WiWi (WiMAX and WiFi) adaptation layer is proposed. The realization of the interworking between these two standards is discussed and evaluated.

Keywords: WiFi, WiMAX, Convergence, Heterogeneous Network, Seamless Handover.

A Model for Header Compression Context Transfer in Cellular IP

by M. Anbar, D. P. Vidyarthi

Abstract - Providing uninterrupted Internet connectivity to mobile users has become a serious challenge in recent as the increasing number of users requires more bandwidth. Time is an equally important factor while providing these services to the mobile users. In mobile computing IP based technologies are extremely important. Mobile IP deals with the management of the IP when the macro mobility is concerned. Cellular networks are used as an access method to the Internet and the other IP-based networks. Cellular IP has been suggested and suited for the micro mobility of the users. Context transfer in Cellular IP protocol incurs an overhead, which often is intolerable as the micro mobility is in concern. The basic idea of the proposed model depends on attaching the context established during Header Compression (HC) process with an IP signaling message and transferring it from base station to another before the handoff operation takes place. Since the proposed model discusses the transfer of Header Compression context, it also shows the importance of Header Compression in reducing the consumed bandwidth through NS-2 simulation experiment. The result reveals the efficacy of the model.

Keywords: macro mobility, micro mobility, Mobile IP, IP Header, IP Context, handoff.

On Analysis of Boundness Property for ECATNets By Using Logic of Concurrency

by N. Boudiaf, K. Bensaber

Abstract - To analyze the behavior of Petri nets, the accessibility graph and Model Checking are widely used. However, if the analyzed Petri net is unbounded then the accessibility graph becomes infinite and Model Checking can not be used even for small Petri nets. ECATNets are a category of algebraic Petri nets. The main feature of ECATNets is their sound and complete semantics based on rewriting logic and its language Maude. ECATNets analysis may be done by using techniques of accessibility analysis and Model Checking defined in Maude. But, these two techniques supported by Maude do not work also with infinite-states systems. As a category of Petri nets, ECATNets can be unbounded and so infinite systems. In order to know if we can apply accessibility analysis and Model Checking of Maude to an ECATNet, we propose in this paper an algorithm allowing the detection if the ECATNet is bounded or not. We exploit the true concurrency of rewriting logic to get an algorithm helping to cope with state explosion problem. Moreover, we propose a rewriting logic based tool implementing this algorithm. We show that Maude system is ideally suited for implementing this algorithm thanks to the reflectivity of the rewriting logic.

Keywords: ECATNets, Rewriting Logic, Maude, True Concurrency, Dynamic Analysis, Finite-State Systems, Infinite-State Systems, Boundness Property Checkness.

A New Mobility Metric for Evaluating Ad Hoc Network Performance

by N. Enneya, M. El Koutbi

Abstract - The performance of an ad-hoc network is closely related to the capability of routing protocols to adapt themselves to unpredictable changes of topology network and link status. In simulations, performance studies of routing protocols depend on the chosen mobility model. Consequently, the comparison of the obtained performance results becomes more difficult. To solve the above problem it is necessary to define a unified mobility measure which is independent of any mobility model. In this paper, we propose a unified quantitative measure of the mobility that is logical and light-weight. Logical, because it has a strong linear relationship with the change of link status for a wide variety of scenarios. Light-weight, because it’s simple to evaluate and to implement in ad-hoc network simulations.

Keywords: Mobility Measure, Mobility Model, Ad-hoc Network, Ad-hoc Routing Protocol, Ad-hoc Performance.

An Adaptive Approach to Anomaly Intrusion Detection Based on Data Mining and String Metrics
by V. G. Jecheva, E. P. Nikolova

Abstract - Various kinds of attacks on computer systems result in increasing the number of security breaches, which become a serious problem in the contemporary network world. An intrusion detection system (IDS) can be utilized to determine if a computer system has experienced an unauthorized intrusion or security breach. The present paper proposes an adaptive approach to anomaly based intrusion detection which is grounded on classification trees and string metrics. Some experimental results, obtained from the conducted simulations, are also represented and discussed.

Keywords: Intrusion Detection, Anomaly Based IDS, Data Mining, Classification Trees, String Metrics.

A New Collaborative System for Industrial Tele-Maintenance
by D. Hedjazi, A. Zidani, M. Boussedjra

Abstract - This paper outlines basic concepts of a design methodology of a new collaborative system for industrial tele-maintenance. The maintenance staff can remotely achieve the work through direct collaboration between the experts’ members within a shared workspace. The system is mainly founded on two separated components, the first one manages administrative considerations of industrial tele-maintenance, the second component manages interaction, coordination, and communication among experts working simultaneously on a common industrial problems. The system is mainly designed to address users’ needs, increase knowledge and skills sharing, information availability, mobility, deep expertise, and to reduce the costs of equipment failures.

Keywords: Collaborative Work, Group Management, Industrial Tele-maintenance, Shared Diagnosis.

A Review on Genetic Algorithm in Parallel & Distributed Environment
by R. K. Jena, P. Srivastava, G. K. Sharma

Abstract - This paper analyzes some technical and practical issues concerning genetic algorithm in parallel and distributed environment. Succinctly, it tries to capture and present some of the most important publications on parallel and distributed genetic algorithm. It also focuses on some of the prominent software’s / tools related to parallel and distributed genetic algorithm.

Keywords: Parallel genetic algorithms, Coarse grain model, Fine grain model, Hybrid genetic algorithms.

A Simple DFE–Based Equalization Technique for Wideband Communications: System Design and Optimization Issues
by K. B. Baltzis

Abstract - This paper presents a low–complexity decision feedback equalizer (DFE) for wideband communications over fading channels. A series of parallel branches that introduce different sampling phase prior to the DFE are used to improve its performance and reduce the complexity of its filters. The Minimum Mean Square Error (MMSE) criterion is applied for the optimization and update of the filters coefficients. Theoretical analysis and simulation results are provided to show the operation of the receiver and demonstrate its performance. Comparisons with relevant techniques are performed to corroborate the merits of the proposal. The effect of the number of branches, the length of the filters and the sampling frequency on the receiver performance is investigated. Interesting conclusions about the complexity reduction of the receiver and the optimization of a wideband wireless communication system have also been obtained.

Keywords: Decision Feedback Equalizer, MMSE, Optimization, Spread Spectrum, Wireless Communications.

A Hybrid Data Integration Approach Based on Specialized Mediators
by F. Boulçane, M. Boufaida

Abstract - Data integration systems are one of the important issues in many distributed architectures like mediation systems. Mediators use a virtual global schema that generalizes over the relevant parts of the sources schemas. There are two basic approaches for designing a data integration system: Global As View (GAV) and Local As View (LAV). In the GAV approach, the global schema is defined in terms of the local sources schemas, while in the LAV approach, the global schema is defined independently of the local sources schemas. To better cope with heterogeneous data integration, this paper presents an integration approach of heterogeneous data. This approach, named HAV (Hybrid As View), aims at combining the best of GAV and LAV, and then reduces their limitations to improve the data integration effectiveness, flexibility and scalability. The paper deals with the problem of the mapping and the query processing and provides some formal definitions based on Lenzerini's formula for data integration. HAV is experimented on a case study and is evaluated qualitatively and quantitatively.

Keywords: heterogeneous data, data integration, mediation system, mediation architecture, GAV, LAV.

Distributed Caml Light
by E. Merah, A. Chaoui

Abstract - In this paper we propose an extension of the functional programming language Caml, exactly Caml Light, that allows it to express concurrent and distributed applications; we call the resulting language Distributed Caml Light. This proposed language will be developed further to support the mobile computation paradigm. For the concurrent and distributed extension of Caml Light, we use the model of ERLANG functional programming language in spite of its simplicity on the one hand and of its success in the development of applications in this area on the other hand. In Distributed Caml Light, processes communicate with each other by sending asynchronous messages. Writing distributed programs in Distributed Caml Light is made by the adaptation of functions used for concurrency.

Keywords: Functional Programming, Concurrency, Distribution, Asynchronous Communication.