Message form the Editors  

DDoS Incidents and their Impact: A Review

Abstract: The phenomenal growth and success of Internet has changed the way traditional essential services such as banking, transportation, medicine, education and defence are operated. Now they are being progressively replaced by cheaper and more efficient Internet-based applications. In present era, the world is highly dependent on the Internet and it is considered as main infrastructure of the global information society. Therefore, the availability of Internet is very critical for the socio-economic growth of the society. However, the inherent vulnerabilities of the Internet architecture provide opportunities for a lot of attacks on its infrastructure and services. Distributed denial-of-service attack is one such kind of attack, which poses an immense threat to the availability of the Internet. One of the biggest challenges before researchers is to find details of these attacks because to avoid defamation most of the commercial sites do not even reveal that they were attacked. In this paper, an overview of distributed denial-of-service problem and Inherent vulnerabilities in the Internet architecture are provided. Real distributed denial-of-service incidents with their financial impact are critically analyzed and finally need for a comprehensive distributed denial-of-service solution is highlighted.

Keywords: Availability, botnet, DoS, DDoS, incident, vulnerability.

Received April 18, 2008; accepted June 8, 2008

Input Variable Selection Using Parallel Processing of RBF Neural Networks

Abstract: In this paper we propose a new technique focused on the selection of the important input variable for modelling complex systems of function approximation problems, in order to avoid the exponential increase in the complexity of the system that is usual when dealing with many input variables. The proposed parallel processing approach is composed of complete radial basis function neural networks that are in charge of a reduced set of input variables depending in the general behaviour of the problem. For the optimization of the parameters of each radial basis function neural networks in the system, we propose a new method to select the more important input variables which is capable of deciding which of the chosen variables go alone or together to each radial basis function neural networks to build the parallel structure, thus reducing the dimension of the input variable space for each radial basis function neural networks. We also provide an algorithm which automatically finds the most suitable topology of the proposed parallel processing structure and selects the more important input variables for it. Therefore, our goal is to find the most suitable of the proposed families of parallel processing architectures in order to approximate a system from which a set of input/output. So that the proposed parallel processing structure outperforms other algorithms not only with respect to the final approximation error but also with respect to the number of computation parameters of the system.

Keywords: Parallel processing, input variable selection, radial basis function neural networks.

Received November 30, 2007; accepted May 12, 2008

An Enhancement of Major Sorting Algorithms

Abstract: One of the fundamental issues in computer science is ordering a list of items. Although there is a huge number of sorting algorithms, sorting problem has attracted a great deal of research; because efficient sorting is important to optimize the use of other algorithms. This paper presents two new sorting algorithms, enhanced selection sort and enhanced bubble Sort algorithms. Enhanced selection sort is an enhancement on selection sort by making it slightly faster and stable sorting algorithm. Enhanced bubble sort is an enhancement on both bubble sort and selection sort algorithms with O(nlgn) complexity instead of O(n2) for bubble sort and selection sort algorithms. The two new algorithms are analyzed, implemented, tested, and compared and the results were promising.

Keywords: Enhanced selection sort, enhanced bubble sort, selection sort, bubble sort, number of swaps, time complexity.  

Received May 27, 2008; accepted September 1, 2008

Performance of OCDMA Systems Using
Random Diagonal Code for Different
Decoders Architecture Schemes 

Keywords: Optical code division multiple access, bit-error rate, phase intensity induced noise, SNR, and modified frequency hopping.

Received April 21, 2008; accepted June 8, 2008

Semiotics Explorations on Designing the Information Intensive Web Interfaces

Abstract: The growth of technological innovations, internet developments, and their (web) applications has raised a definite issue on retaining the web interface quite understandable. Moreover, a need is also being felt on developing suitable and coherent guidelines for designing interface to swell the user interpretability of web signs. These design principles are semiotics by nature and semiotics is the science of signs, that is, meaning’s of representations. For this, new and important perspectives for interface design would be discovered by semiotic analysis on interface signs. Therefore, this research mainly focuses on the valuable insights that semiotic analysis could offer to present the fundamental concepts to create understandable signs. The fundamental role of this research is to provide the semiotics background to the web designers with presenting the entire semiotics explanations for a particular web domain and the semiotics golden rules that will help them to designing the web interface signs comprehensible and usable to work with.

Keywords: Usability, human computer interaction, web interface, empirical study.

Received May 4, 2008; accepted June 8, 2008

Low Latency, High Throughput, and Less Complex VLSI Architecture for 2D-DFT

Keywords: Digital signal processing chip, discrete Fourier transforms, systolic array, and very-large-scale integration circuit.

Received February 22, 2008; accepted June 8, 2008

Specification and Prototyping of Reactive Distributed Systems with Algebraic Term Nets

Abstract: The specification of the dynamic behaviour of reactive distributed systems must exhibit the structures of control and has to imply explicitly the relevant aspects of the distribution, such as the concurrency, the reactivity and the interaction between the entities. Among the most common reactive distributed systems we can cite industrial ones; distributed networks occur for example in telecommunications, Internet, power and energy, transportation and manufacturing. Distributed computing will play an increasingly critical role in the global industrial-infrastructure. The need for trustworthy systems has received tremendous researchers’ attention. The usage of formal tools for simulation and rototyping designed to facilitate the modelling of such systems is of great interest. Improved methods are needed to insure reliability, security and robustness of industrial distributed systems. This paper proposes the fundamentals of a formal approach for the specification of reactive distributed systems based on object-oriented paradigm. Object’s behaviour is modelled as REACTNets. The REACTNets enhance the ECATNets that are a kind of high level algebraic Petri nets with explicit distribution and reactivity. We associate to the classic ECATNets MAUDE rules to handle interactions between objects. The two formalisms have a common semantics in term of rewriting logic so that interesting prospects are opened for their integration.

Keywords: Reactive distributed systems, object oriented paradigm, rewriting logic, ECATNets, Maude, rapid prototyping.

 Received February 5, 2008; accepted September 1, 2008

Variable Rate Steganography in Gray Scale Digital Images Using Neighborhood
Pixel Information

Abstract: Steganography is the art of hiding the fact that communication is taking place, by hiding information in other information. Security has always been a major concern since time immemorial. In the past, people used hidden tattoos or invisible ink to convey steganographic content. Today, digital technology and Internet provide for easy to use cover media for steganography. In order to improve the security by providing the stego image with imperceptible quality, three different steganographic methods for gray level images are presented in this paper. Four neighbors, diagonal neighbors and eight neighbors methods are employed in our scheme. These methods utilize a pixel’s dependency on its neighborhood and psycho visual redundancy to ascertain the smooth areas and complicated areas in the image. In smooth areas we embed three bits of secret information. In the complicated areas, variable rate bits are embedded. From the experimental results it is seen that the proposed methods achieve a much higher visual quality as indicated by the high peak signal-to-noise ratio in spite of hiding a larger number of secret bits in the image. In addition, to embed this large amount of secret information, at most only half of the total number of pixels in an image is used. Moreover, extraction of the secret information is independent of original cover image.

Keywords: Information security, steganography, data hiding, stego image, cover image.

 Received October 27, 2007; accepted February 11, 2008

Ontology-Based Intelligent Mobile Search Oriented to Global e-Commerce

Abstract: In this paper we propose a novel approach for searching eCommerce products using a mobile phone, illustrated by a prototype eCoMobile. This approach aims to globalize the mobile search by integrating the concept of user multilinguism into it. To illustrate that, we particularly deal with English and Arabic languages. Indeed the mobile user can formulate his query on a commercial product in either language (English/Arabic). The description of his information need on commercial products relies on the ontology that represents the conceptualization of the product catalogue knowledge domain defined in both English and Arabic languages. A query expressed on a mobile device client defines the concept that corresponds to the name of the product followed by a set of pairs (property, value) specifying the characteristics of the product. Once a query is submitted it is then communicated to the server side which analyses it and in its turn performs an http request to an eCommerce application server (like Amazon.com). This latter responds by returning an XML file representing a set of elements where each element defines an item of the searched product with its specific characteristics. The XML file is analyzed on the server side and then items are displayed on the mobile device client along with its relevant characteristics in the chosen language.

Keywords: Mobile computing, search engine, multilingual global eCommerce, ontology, XML.

Received March 10, 2008; accepted June 08, 2008

A Quantum-Inspired Differential Evolution Algorithm for Solving the N-Queens Problem

Keywords: Quantum computing, differential evolution, N-queens problem, combinatorial optimization.

Received March 20, 2008; accepted July 8, 2008

Modelling of Updating Moving Object Database Using Timed Petri Net Model

Abstract: Tracking moving objects is one of the most common requirements for many location-based applications. The location of a moving object changes continuously but the database location of the moving object cannot update continuously. Modelling of such moving object database should be considered to facilitate study of the performance and design parameters for this database feature. Such study is essential for selecting the optimal solution in order to minimize the implementation of the overhead cost. Location updating strategy for such type of database is the most important criteria. This paper proposed a timed Petri net model based on one of the most common updating strategies, namely the distance updating strategy. In addition, a method for estimating the time needed to update moving object database  using the concept of the minimum cycle time in timed Petri nets is presented. This time is the main criterion, which can be used to study the overhead communication cost for moving object database. A typical numerical example is given to demonstrate the advantages of proposed modelling technique.

Keywords: Updating moving object database, deterministic timed Petri net, deviation update policy,  tracking moving object database.

Received June 15, 2008; accepted September 3, 2009

Identification of Promoter Region in Genomic DNA Using Cellular Automata Based Text Clustering

Keywords: Text clustering, DNA sequence, cellular automata.

Received May 10, 2008; accepted October 1, 2008

HW/SW Design-Based Implementation of Vector Median Rational Hybrid Filter

Abstract: A new code sign implementation of vector median rational hybrid filter based on efficient hardware/software implementation is introduced and applied to colour image filtering problems. This filter is used essentially to remove impulsive and Gaussian noise in colour images. In our design we start by implementing the software solution in system on programmable chip context using NIOS-II softcore processor and µClinux as operating system. We evaluate the execution time of the whole filtering process. Than we add a hardware accelerator part. This latter is implemented using fast parallel architecture. Compared to the software solution results, the use of the hardware accelerator improves clearly the filtering speed and maintains the good filtering quality as shown by simulations.

Keywords: Filtering, co-design, FPGA implementation, SoPC, NIOS-II processor.

Received January 1, 2008; accepted September 11, 2008

Optimal DSP Based Integer Motion Estimation Implementation for H.264/AVC Baseline Encoder

Abstract: The coding gain of the H.264/AVC video encoder mainly comes from the new incorporated prediction tools. However, their enormous computation and ultrahigh memory bandwidth are the penalties. In this paper we present an approach supporting efficient data reuse process to avoid unnecessary memory accesses and redundant motion estimation computations combined with a novel fast algorithm. A merging procedure joining search origin, search pattern and new variable block size motion estimation for H.264/AVC is detailed in this paper. Those approaches yield good tradeoffs between motion estimation distortion and number of computations since they invest and exploit the centre-biased characteristics of the real world video sequences: a reliable predictor determines the search origin, localizing the search process. An efficient search pattern exploits structural constraints within the motion field. A new fast block size selection DSP-based algorithm allows simultaneous fidelity of the video quality and the reduction of the computational cost. Extensive experimental work has been done, results of which show that our approach gives a speed up of 1.14 times over that of the recent fast algorithms and 10 times over the spiral search algorithm on average, with a negligible degradation in peak signal-to-noise ratio. In addition, interesting memory bandwidth is further saved with the proposed data reuse techniques at architecture level.

Keywords: H.264/AVC, search centre, block matching algorithm, pattern search, variable block size, complexity, video quality, PSNR, SSIM.

 Received March 7, 2008; accepted September 1, 2008

Representing Uncertainty in Medical Knowledge: An Interval Based Approach for
Binary Fuzzy Relations

Keywords: Binary fuzzy relation, interval valued representation, medical knowledge representation, fuzzy inclusion measure, uncertainty, fuzzy logic.

 Received April 23, 2008; accepted September 1, 2009