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International Review on Computers and Software - November 2006 - Papers

SIDERA - A Simulation Model for Time-Triggered Distributed Real-Time Systems
Web Services and Data Integration in Distributed Automation and Information Systems in Internet Environment
Grid Middleware Technologies and OGSA: A Comparative Study
A Hybrid Protocol for Consistency Management of Replicas in OptorSim Simulator
A Low Cost Multipurpose Algorithm for Secure Transfer of Medical Images
Wavelet Based Speckle Filtering of the SAR Images
Genetic Algorithm for Task Scheduling on Distributed Heterogeneous Computing System
Logitboost of Multinomial Bayesian Classifier for Text Classification
Supporting Data Changes in Multidimensional Data Warehouses
A Rewriting Logic Based Tool for ECATNets Coverability Analysis

International Review on Computers and Software - Papers

SIDERA - A Simulation Model for Time-Triggered Distributed Real-Time Systems
by A. Hanzlik

Abstract - SIDERA (SImulation model for DEpendable Real-time Architectures) is a simulation model for time-triggered distributed real-time systems. It is based on the Time-Triggered Architecture TTA and allows the simulation of large-scale real-time systems. SIDERA provides simulation of various real-time protocol services like system startup, communication, clock synchronization, membership service and protocol error detection and handling. A failure simulation module allows testing the stability of the systems under investigation in the presence of node failures. This paper is about basic concepts of time-triggered distributed systems and the implementation of these concepts in a simulation environment. Further, it provides a case study of clock synchronization in distributed systems and presents an approach that significantly improves the synchronism in a distributed system while reducing the need for high-quality oscillators.

Keywords: Simulation, Clock Synchronization, Time-Triggered Systems, Distributed Real-Time Computing.

Web Services and Data Integration in Distributed Automation and Information Systems in Internet Environment

by N. Kakanakov, M. Shopov, I. Stankov, G. Spasov

Abstract - In this paper an abstract model for adaptation of enterprise technologies in heterogeneous networks of small devices is proposed. The model is based on hierarchical multi-tier approach for better manageability and administration. Its structure allows not only separation between business and presentation logic, but also separation of enterprise and automation functions. Thus, changes in business and automation logics do not affect the user. The actual distribution of functions appears on the service and automation tiers. The level of abstraction of the model allows its usage in various environments – home and office automation, industry, medicine, agriculture. In the paper an experimental application of the presented model for an effective management of HVAC (heating, ventilation and air conditioning) systems in buildings is discussed.

Keywords: N-tier model, distributed computing, embedded systems, Industrial Ethernet, HVAC.

Grid Middleware Technologies and OGSA: A Comparative Study
by I. Chana, S. Bawa

Abstract - Grid Resource Management refers to the operations used to control the capabilities provided by Grid resources and the services that are made available to other entities. Grid enables the selection and sharing of a wide variety of geographically distributed resources including super computers, High Performance Computers (HPC), Massively Parallel Processors (MPPs), storage systems, data sources, and other such resources for solving compute-intensive and data-intensive problems. This sharing of resources is a complicated task, as it requires the ability to bridge the differing resource management requirements of the resource owners. Different resource owners use different middleware for resource management as a standard middleware framework is yet to be developed. OGSA has come up as a benchmark for this standardization. It defines principle standards, which every grid system must adhere to, to become a future, global grid. This paper surveys the resource models for popular Grid middleware- Globus, UNICORE, Legion, Alchemi and SUN Grid Engine. It then compares these middleware w.r.t. OGSA standards.

Keywords: Grid middleware, Grid Computing, OGSA, Resource Management.

A Hybrid Protocol for Consistency Management of Replicas in OptorSim Simulator
by G. Belalem, Y. Slimani, B. Beldjilali

Abstract - In large scale distributed systems, technique of replication is one of the popular research topics and is a widely accepted way to improve the accessibility of information and to survive the unreliability of communication networks, but the use of this technique can be very expensive to take account the consistency management of the replicas. In this paper, we present an extension of the OptorSim simulator by a consistency management module of the replicas in the Data Grids. The consistency manager inspired by the pessimistic and optimistic approaches of consistency, this suggested approach has two vocations, in the first time, it makes it possible to reduce the response times compared with the completely pessimistic approach, in the second time, it gives a good quality of service compared with the optimistic approach.

Keywords: Data Grid, Replication, Optimistic approach, Pessimistic approach, Consistency, OptorSim.

A Low Cost Multipurpose Algorithm for Secure Transfer of Medical Images

by S. Boucherkha, Z. Laboudi, M. Benmohamed

Abstract - On-line medical image distribution is widely used nowadays between healthcare institutions. Medical images are a type of data requiring a large processing capacity and transmission bandwith, so, compression is often mandatory. Besides, the integrity and confidentiality of image content is a critical issue due to diagnostic and ethics requirements. In this work, we aim at giving an efficient scheme to provide confidentiality for the transmission of medical images and related data with a minimal computational effort. The proposed system consists of an efficient combination of a lossless compression algorithm, encryption in a CBC mode, and spatial domain watermarking to embed patient information in the related medical image. We demonstrate experimentally that by interleaving basic algorithms for compression, embedding and encryption in a one-pass algorithm, we can achieve better computational performance than by using the same algorithms in separate stages while maintaining the same security level and compression rate.

Keywords: Medical Images, Compression, Cryptography, Watermarking, Confidentiality.

Wavelet Based Speckle Filtering of the SAR Images

by K. K. Gupta, R. Gupta

Abstract - Synthetic Aperture Radar (SAR) images are corrupted by speckle noise due to random interference of electromagnetic waves. The speckle degrades the quality of the image and makes difficult to interpret, analysis and classification of the SAR images. This paper proposes a method that reduces the speckle and preserves the features. The features are preserved by using scale-space correlation between the scales. The results show that the proposed method is better than widely used filters based on the spatial domain, such as Lee, Kuan, Frost, Ehfrost, Median, Gamma filters in terms of feature preservation. Moreover the proposed method achieves a wide range of balances between speckle reduction and feature preservation, and thus is applicable in different applications such as road detection, bridge, and ribbon like structure. Further more, the proposed method does not require prior modeling of either the image or noise statistics. It uses the variance of the detail wavelets coefficients to estimate noise variance.
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Keywords: Speckles, wavelet transform, multiresolution analysis.

Genetic Algorithm for Task Scheduling on Distributed Heterogeneous Computing System

by E. Ilavarasan, P. Thambidurai

Abstract - Distributed heterogeneous computing system are increasingly being employed for critical applications, such as aircraft control, industrial process control, and banking systems. Efficient application scheduling is a key issue for achieving high performance in this system. The problem is generally addressed in terms of task scheduling, where the tasks are the schedulable units of a program. The task scheduling problem has been extensively studied and a large number of scheduling heuristics have been presented in the literature. In this paper we propose a new task-scheduling algorithm namely, Genetic Algorithm for Task Scheduling (GATS) on heterogeneous computing system, which provides optimal results for applications represented by directed acyclic graph. The performance of the algorithm is illustrated by comparing the schedule length, speedup, and efficiency with existing algorithms such as CPOP, HEFT and PSGA. The comparison study based on randomly generated graphs and graphs of three real world applications such as Gaussian Elimination Algorithm, Fast Fourier Transformation, and Gauss Jordan algorithm shows that GATS algorithm substantially outperforms existing algorithms.

Keywords: Task Graph, DAG, Scheduling, Heterogeneous Computing System, Schedule length.

Logitboost of Multinomial Bayesian Classifier for Text Classification

by S. Kotsiantis, E. Athanasopoulou, P. Pintelas

Abstract - Automated text classification has been considered as a vital method to manage and process a vast amount of documents in digital forms that are widespread and continuously increasing. In general, text classification plays an important role in information extraction and summarization, text retrieval, and question-answering. The Multinomial Bayesian Classifier has traditionally been a focus of research in the field of text learning. This paper increases the accuracy of Multinomial Bayesian Classifier with the usage of the Logitboost technique. We performed a large-scale comparison on benchmark datasets with other state-of-the-art algorithms and the proposed technique had greater accuracy in most cases.

Keywords: text mining, learning algorithms, text representation.

Supporting Data Changes in Multidimensional Data Warehouses
by F. Ravat, O. Teste

Abstract - This paper is in the field of data warehouses based on “On-Line Analytical Processing” (OLAP) technology. We detail the integration of changes in a multidimensional schema. First, the conceptual model we provide integrates the changes of facts (subject of analysis) and dimensions (axes of analysis). These changes are modeled through fact and dimension versions. Second, the logical model we provide is based on Relational-OLAP concepts. The conceptual versions are translated into data version tables and structure tables.

Keywords: Multidimensional model, Data versions, R-OLAP.

A Rewriting Logic Based Tool for ECATNets Coverability Analysis
by N. Boudiaf, A. Chaoui

Abstract - To analyze the behavior of Petri nets, the reachability graph allows verifying qualitative properties. However, even for small nets, the reachability graph can become infinite if the analyzed Petri net is unbounded. To deal with the state space explosion problem, lazy construction methods to consider only reduced state spaces have been elaborated. For example, the stubborn set reduced reachability graph is usually much smaller than the complete one, but it exhibits all dead states, if any. For unbounded nets, coverability graphs must be used. ECATNets are a category of algebraic Petri nets based on a sound combination of algebraic abstract types and high level Petri nets. The most distinctive feature of ECATNets is that their semantics is defined in terms of rewriting logic and its language Maude, allowing us to built models by formal reasoning. In this paper, we propose a rewriting logic based tool that implements an algorithm aiming the construction of coverability graph for ECATNet. Some qualitative properties such as the absence of deadlock can be checked using the constructed coverability graph. The development of this tool is facilitated thanks to the concept of the reflectivity of rewriting logic : the self-interpretation of this logic allows us both the modelling of an ECATNet and acting on it. The tool is illustrated through an example.

Keywords: Coverability Graph, ECATNets, Rewriting Logic, Maude, Dynamic Analysis, Finite-state Systems, Infinite-state Systems.