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This review paper presents the current state-of-the-art pertains to water pipe failure prediction and risk assessment, published in the last ten years (2009-2019). This paper has been motivated by the lack of comprehensive review articles that integrates water network failure and risk modeling. Some of the current practices reviewed the pipe condition and its failure. Others focused on the statistical prediction models, whereas the rest outlined failure prediction models of large diameter mains only. The mainstream of the current practice, highlighted in this paper characterizes the structural deterioration and failure rates using various statistical techniques, whereas the remainder of research covers a proliferation of machine learning and soft computing applications to forecast and model the pipeline risk of failure. The review offers descriptions of the models together with their proposed methodologies, algorithms and equations, contributions and drawbacks, comparisons and critiques, and types of data used to develop the models using the bibliographic review method. Finally, future work and research challenges are recommended to assist the civil engineering research community in setting a clear agenda for the upcoming research. Key words: pipe failure, risk analysis, prediction models, water main deterioration, water main rehabilitation, infrastructure, state-of-the-art review. Le present article de synthese presente l'etat actuel des realisations en matiere de prevision des defaillances de conduites d'eau et revaluation des risques, tel que publie au cours des dix dernieres annees (2009-2019). C'est l'absence d'etudes globales integrant la defaillance d'un reseau d'eau et la modelisation des risques qui a motive cette etude. Certaines des pratiques actuelles ont examine l'etat de la conduite et sa defaillance. D'autres ont porte sur les modeles de prediction statistique, tandis que les autres ont decrit les modeles de prediction de defaillances de conduites principales de grand diametre seulement. Le courant dominant de la pratique actuelle, mis en evidence dans le present document, caracterise la deterioration structurelle et les taux de defaillance a l'aide de diverses techniques statistiques, alors que le reste de la recherche porte sur une multitude d'applications d'apprentissage automatique et de calcul electronique pour prevoir et modeliser le risque de defaillance de pipeline. La revue propose des descriptions de modeles ainsi que leurs methodologies, algorithmes et equations proposes, leurs contributions et inconvenients, des comparaisons et critiques, et les types de donnees utilisees pour elaborer les modeles a l'aide de la methode de la revue bibliographique. Enfin, on suggere les prochains travaux et les defis associes a la recherche pour aider le milieu de la recherche en genie civil a etablir un programme clair pour la recherche a venir. [Traduit par la Redaction] Mots-cles: defaillance de conduites, analyse des risques, modeles de prediction, deterioration de conduite principale, rehabilitation de conduite principale, infrastructure, revue sur l'etat actuel des connaissances., Introduction Water supply networks have always been an integral part of public infrastructure and a vital constituent of the national assets. Unfortunately, communities all over the world experience undesired incidents [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2010.05.001 Byline: Li Chunlin, Li Layuan Keywords: Mobile grid; Context; Joint optimization Abstract: This paper presents joint contexts optimization in mobile grid. The paper describes device context information for context-aware services in the mobile device collaboration. The objective of the paper is to dynamically deliver services to mobile grid users according to current context of mobile grid environment. A utility function is used as objective function that expresses values for the current contexts. The optimization is carried out by the joint context parameter optimizer with respect to an objective function. A joint contexts optimization algorithm is proposed which decomposes mobile grid system optimization problem into sub-problems. In the experiment, the performance evaluation of joint contexts optimization algorithm is conducted. Author Affiliation: Department of Computer Science, Wuhan University of Technology, Wuhan 430063, PR China Article History: Received 12 August 2009; Revised 29 March 2010; Accepted 10 May 2010 Article Note: (footnote) [star] Reviews processed and proposed for publication to the Editor-in-Chief by Associate Editor Prof. H. Dag.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.10.002 Byline: Wen-Fang Yen (a), Shingchern D. You (b), Yung-Chao Chang (c) Keywords: Real-time FFT; Real-time signal processing; Completion delay Abstract: The technique of pre-calculation process for real-time FFT is presented in this paper. The real-time FFT algorithm simultaneously constructs and computes the butterfly modules while the incoming data is collected. Thus, the time to complete the FFT calculation is shorter when compared to the conventional FFT. The proposed pre-calculation process that can further reduce this time is verified. Furthermore, depending on the computing capability of the processor, different number of pre-calculation stages for better performance is also suggested in the paper. For a critical mission requiring a shorter time to complete the FFT calculation, the proposed approach is a better choice. Author Affiliation: (a) Department of Electronic Engineering, Hwa Hsia Institute of Technology, 111, Gong Jhuan Rd., Chung Ho, Taipei, Taiwan, ROC (b) Department of Computer Science and Information Engineering, National Taipei University of Technology, 1, Sec. 3, Chung-Hsiao East Rd., Taipei, Taiwan, ROC (c) Delhum Technology and Service Corp., 9F, 332, Sec. 1, Tun-Hwa South Rd., Taipei, Taiwan, ROC Article History: Received 15 April 2008; Accepted 22 October 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.09.009 Byline: Soonhak Kwon (a), Chang Hoon Kim (b), Chun Pyo Hong (c) Keywords: Systolic array; LSB first algorithm; Finite field arithmetic; VLSI; Trinomial Abstract: Systolic arrays for multiplication in GF(2.sup.m) of Yeh et al. with LSB (least significant bit) first algorithm have the unfavorable properties such as increased area complexity and bidirectional data flows compared with the arrays of Wang and Lin with MSB (most significant bit) first algorithm. In this paper, by using a polynomial basis with LSB first algorithm, we present new bit parallel and bit serial systolic arrays over GF(2.sup.m). Our bit parallel systolic multiplier has unidirectional data flows with seven latches in each basic cell. Also our bit serial systolic array has only one control signal with eight latches in each basic cell. Thus our new arrays with LSB first algorithm have shorter critical path delay, comparable hardware complexity, and have the same unidirectional data flows compared with the arrays using MSB first algorithm. We also present new linear systolic arrays for multiplication in GF(2.sup.m) using irreducible trinomial x.sup.m+x.sup.k+1. It is shown that our linear arrays with trinomial basis have reduced hardware complexity since they require two fewer latches than the linear systolic arrays using general irreducible polynomials. Author Affiliation: (a) Institute of Basic Science and Department of Mathematics, Sungkyunkwan University, Suwon 440-746, Republic of Korea (b) School of Computer and Information Technology, Daegu University, Kyungsan 712-714, Republic of Korea (c) School of Computer and Communication Engineering, Daegu University, Kyungsan 712-714, Republic of Korea Article History: Received 7 April 2008; Revised 21 August 2008; Accepted 11 September 2008 Article Note: (footnote) [star] This paper is an extended and revised version of the paper presented at ISCAS 2003 (IEEE Symposium on Circuits and Systems). Also, this paper was supported by Faculty Research Fund, Sungkyunkwan University, 2007.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2007.05.006 Byline: Grace Elias, Ali Miri, Tet-Hin Yeap Keywords: Reconfigurable hardware; Public key cryptosystems; Algorithms implemented in hardware Abstract: In this age, where new technological devices such as PDAs and mobile phones are becoming part of our daily lives, providing efficient implementations of suitable cryptographic algorithms for devices built on embedded systems is becoming increasingly important. This paper presents an efficient design of a high-performance hyperelliptic curve cryptosystem for a field programmable gate array which is well suited for embedded systems having limited resources such as memory, space and processing power. In this paper, we investigate two architectures, one using a projective coordinate representation for hyperelliptic systems and the second using a mixed coordinate representation that eliminates the need for field inversions in the point arithmetic, which has been proven to be expensive in both time and space. In addition, both architectures are based on an explicit formula which allows one to compute the point arithmetic directly in the finite field, thereby eliminating a level of arithmetic. The operation time for the HECC system is also improved by considering simplifications of the hyperelliptic curve which are accomplished through simple transformation of variables. As a result, these implementations offer significantly faster operation time and smaller area consumption then other HECC hardware implementations done to date. Author Affiliation: School of Information Technology and Engineering, University of Ottawa, Ottawa, Canada

Ultrasonic guided waves have been used extensively for long-range pipe inspections. The technique is based on detecting the guided wave echoes reflected from pipe defects located at a remote distance. The axial location of the defect from the transducer can be determined by the arrival time of the echo. However, further information about the defect, such as the circumferential size or distribution of the defect, is hard to obtain with conventional guided waves. This problem will be a critical issue for applications, such as discriminating the pipe corrosion defects from pipe welds. In this paper, a circumferential guided wave array is built for sending and receiving guided waves along the pipe. All of the elements are connected to a single channel pulser/receiver through multiplexers. An algorithm based on two-dimensional (2D) blind deconvolution is developed to process the guided wave echoes acquired by the multiplexed circumferential transducer array. The output of the algorithm can be utilized for evaluating the circumferential distributions and geometry of the defects. The processing algorithm is verified via both numerical simulations and experiments in the paper This circumferential sizing algorithm can serve as an effective postanalysis tool for most available guided wave pipe inspection systems.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2005.09.005 Byline: Ergun Ercelebi (a), Abdulhamit SubaAi (b) Keywords: Audio watermarking; Digital watermarking; Copyright protection; Multimedia security; Pseudo-random sequence Abstract: A robust multi bit and high quality audio watermarking technique in time domain is proposed in this paper. Watermarking is a technique used to label digital media by hiding copyright or other information into the underlying data. The watermark must be imperceptible and undetectable by the user and should be robust to various types of distortion. To enhance the robustness and taper-resistance of the embedded watermark, in this paper a multi bit technique is employed. Instead of embedding one bit into an audio frame, multiple bits can be embedded into each audio sub-frame. For attackers, since they do not know the parameters, this significantly reduces the possibility of unauthorized bit detection and removal of watermark. In real-time watermarking applications, robustness is not the only factor that plays an important role. The other factor that plays a very an important role is computational complexity. In general, audio file is transmitted in compressed form. Real-time watermark embedding must take into account this compressed form, because first decompressing the data, adding a watermark and then recompressing the data is computationally too demanding. In this paper, we propose robust and low complexity audio watermarking algorithm. To evaluate the performance of the proposed audio watermarking algorithm, subjective and objective quality tests including bit error rate (BER) and signal-to-noise ratio (SNR) were conducted. Compared to traditional one bit embedding algorithm, the proposed algorithm gives highly recovery rate after attack by commonly used audio data manipulations, such as low pass filtering, requantization, resampling, and MP3 compression. Author Affiliation: (a) Department of Electrical and Electronics Engineering, University of Gaziantep, 27310 Gaziantep, Turkey (b) Department of Electrical and Electronics Engineering, Kahramanmaras Sutcu Imam University, 46100 Kahramanmaras, Turkey Article History: Received 15 March 2005; Revised 20 August 2005; Accepted 8 September 2005

This paper proposes a novel vehicle routing and scheduling problem in transporting hazardous materials for networks with multiple time-varying attributes. It actually aims to identify all nondominated time-varying paths with departure times at the origin and waiting times at intermediate nodes along these paths for a given pair of origin and destination, subject to three kinds of practical constraints: Limited operational time period, and service, and waiting time window constraints at a node. Based on the assumption of linear waiting attributes at a node, the proposed problem can be equivalently transformed into a static multiobjective shortest path problem in an acyclic network reconstructed by the space-time network technique. An efficient dynamic programming method is then developed. In addition, two numerical examples and a case study are carried out to demonstrate the methodology proposed in this paper. DOI: 10.1061/(ASCE)0733-947X(2005)131:9(699) CE Database subject headings: Hazardous materials; Multiple objective analysis; Transportation networks; Routing; Scheduling; Algorithms.

The notion of optimization is inherent in the design of a sequence of amino acid monomer types in a long heteropolymer chain of a protein that should fold to a desired conformation. Building upon our previous work wherein continuous parametrization and deterministic optimization approach were introduced for protein sequence design, in this paper we present an alternative formulation that leads to a quadratic programming problem in the first stage of a two-stage design procedure. The new quadratic formulation, which uses the linear interpolation of the states of the monomers in Stage I could be solved to identify the globally optimal sequence(s). Furthermore, the global minimum solution of the quadratic programming problem gives a lower bound on the energy for a given conformation in the sequence space. In practice, even a local optimization algorithm often gives sequences with global minimum, as demonstrated in the examples considered in this paper: The solutions of the first stage are then used to provide an appropriate initial guess for the second stage, where a rescaled Gaussian probability distribution function-based interpolation is used to refine the states to their original discrete states. The performance of this method is demonstrated with HP (hydrophobic and polar) lattice models of proteins. The results of this method are compared with the results of exhaustive enumeration as well as our earlier method that uses a graph-spectral method in Stage 1. The computational efficiency of the new method is also demonstrated by designing HP models of real proteins. The method outlined in this paper is applicable to very large chains and can be extended to the case of multiple monomer types. [DOI: 10.1115/1.1901705]

Mobile crane manufacturers provide operators and practitioners with tabulated lift-capacity charts. These charts are structured based on predetermined crane configurations, which consist of boom/jib length, lifting radius, lifting height, main boom angles to ground, and jib angle to ground or its offset to its main boom centerline. Practitioners, however, are often required to lift on a partially extended hydraulic section and/or lifting radius other than those listed in the manufacturers' lift-capacity charts. This paper presents a newly developed optimization algorithm (referred to in this paper as Algorithm-2) for selecting and locating mobile cranes on construction sites based on their minimum boom length and/or minimum radius, accordingly higher lifting capacities. Algorithm-2 includes an optimization procedure that avoids lifting capacity violations. In addition to the practical use of Algorithm 2, the mathematical representations of the crane's geometry are also useful for research in the automation and robotic field of operations involving cranes. The algorithm is incorporated into a computer system that integrates a selection module and a database. Data pertinent to crane lift configurations are retrieved from the database and are then processed to determine the optimum, geometrical selection of the crane configuration. A case example is described in order to demonstrate the use of the developed algorithm and to illustrate its essential features. DOI: 10.1061/(ASCE)0733-9364(2005)131:5(579) CE Database subject headings: Cranes; Optimization; Databases.

This study, evaluates the resource-constrained critical path method (RCPM). which the writers have recently proposed. RCPM establishes a critical path method (CPM)-like. resource-constrained schedule by resource-dependent activity relationships (or resource links) thai the five-step RCPM technique identifies. With its CPM-like feature. RCPM provides the critical path and float data that are not available in traditional resource-constrained scheduling techniques. In addition. RCPM provides more flexibility to the schedule through identified alternative schedules, which allow certain activities to be executed beyond their late finish times without delaying the project completion. This paper evaluates the RCPM's performance by comparing it with five related previous studies. A brief review of each study is also included in this paper. This comparison shows that RCPM performs well in identifying resource links and alternative schedules. compared to other methods. This study is of interest to academics because it highlights the advantages and disadvantages of different algorithms that have attempted to overcome present problems in traditional resource-constrained scheduling techniques. DOI: 10.1061/(ASCE)0733-9364(2005)131:5(522) CE Database subject headings: Scheduling; Critical path method; Resource allocation; Construction management.

In a real construction project, the duration and cost of each activity could change dynamically as a result of many uncertain variables, such as weather, resource availability, productivity, etc. Managers/planners must take these uncertainties into account and provide an optimal balance of time and cost based on their own experience and knowledge. In this paper, fuzzy sets theory is applied to model the managers' behavior in predicting time and cost pertinent to a specific option within an activity. Genetic algorithms are used as a searching mechanism to establish the optimal time-cost profiles under different risk levels. In addition, thee nonreplaceable front concept is proposed to assist managers in recognizing promising solutions from numerous candidates on the Pareto front. Economic analysis skills, such as the utility theory and opportunity cost, are integrated into the new model to mimic the decision making process of human experts. A simple case study is used for testing the new model developed. In comparison with the previous models, the new model provides managers with greater flexibility to analyze their decisions in a more realistic manner. The results also indicate that greater robustness may be achieved by taking some risks. This research is relevant to both industry practitioners and researchers. By incorporating the concept of fuzzy sets, managers can represent the range of possible time-cost values as well as their associated degree of belief. The model presented in this paper can, therefore, support decision makers in analyzing their time-cost optimization decision in a more flexible and realistic manner. Many novel ideas have also been incorporated in this paper to benefit the research community. Examples of these include the use of fuzzy sets theory, nonreplaceable front concept, utility theory, opportunity cost, etc. With suitable modifications, these concepts can be applied to model to other similar optimization problems in construction. CE Database subject headings: Fuzzy sets; Algorithms; Risk management; Stochastic processes; Time factors; Cost control; Project management; Productivity.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2004.07.002 Byline: S. Srinivasan, D.P. Mital, S. Haque Abstract: In this paper we have addressed the problem of finding a path through a maze of a given size. The traditional ways of finding a path through a maze employ recursive algorithms in which unwanted or non-paths are eliminated in a recursive manner. Neural networks with their parallel and distributed nature of processing seem to provide a natural solution to this problem. We present a biologically inspired solution using a two level hierarchical neural network for the mapping of the maze as also the generation of the path if it exists. For a maze of size S the amount of time it takes would be a function of S (O(S)) and a shortest path (if more than one path exists) could be found in around S cycles where each cycle involves all the neurons doing their processing in a parallel manner. The solution presented in this paper finds all valid paths and a simple technique for finding the shortest path amongst them is also given. The results are very encouraging and more applications of the network setup used in this report are currently being investigated. These include synthetic modeling of biological neural mechanisms, traversal of decision trees, modeling of associative neural networks (as in relating visual and auditory stimuli of a given phenomenon) and surgical micro-robot trajectory planning and execution. Author Affiliation: Department of Health Informatics, UMDNJ -- School of Health Related Professions, 65 Bergen St., Newark, NJ 07107-3001, United States

Development lending institutions are exploring solutions that can ensure the effectiveness of funds. Results-based financing (RBF) considers this goal by linking desired outputs to the disbursement of funds. This may require borrowers to prefinance programs and then receive allocated disbursements after achieving results, which forms cash flow gaps. This paper presents a framework for the simulation and optimization of RBF programs using genetic algorithms (GA). It applies finance-based scheduling on RBF multiple projects to obtaining an improved benefit from borrowed funds. The Program-for-Results (P4R) mechanism offered by the World Bank (WB) was used as one of the RBF mechanisms for verification. It was validated using the Sustainable Rural Sanitation Services Program (SRSSP) in Egypt and improved the overall financial standing of the government. This model introduces an enhanced financing environment for RBF mega-programs, enabling borrowers to apply for the RBF mechanism. Key words: managing multiple projects, loans, cash flow, financial management, genetic algorithms. Les etablissements de credit au developpement explorent des solutions qui peuvent assurer l'efficacite des fonds. Le financement axe sur les resultats (FAR) tient compte de cet objectif en etablissant un lien entre les extrants souhaites et le decaissement des fonds. Cela peut necessiter que les emprunteurs financent prealablement les programmes, puis recoivent leurs decaissements alloues apres avoir atteint les resultats, ce qui forme des ecarts de tresorerie. Cet article presente un cadre pour la simulation et l'optimisation des programmes FAR, en utilisant des algorithmes genetiques (GA). Ce cadre applique un calendrier financier sur plusieurs projets FAR, pour obtenir un meilleur benefice des fonds empruntes. Le mecanisme du Programme pour les resultats (PPR) offert par la Banque mondiale (BM) a ete utilise comme l'un des mecanismes du FAR pour la verification. Il a ete valide au moyen du Programme de services d'assainissement rural durable (PSARD) en Egypte, et il a ameliore la situation financiere globale du gouvernement. Ce modele introduit un environnement de financement ameliore pour les megaprogrammes de FAR, permettant aux emprunteurs de demander le mecanisme de FAR. [Traduit par la Redaction] Mots-cles: gerer de multiples projets, prets, flux de tresorerie, gestion financiere, algorithmes genetiques., Introduction Financing multiple projects, specifically in the infrastructure sector, requires huge investments. This entails supplying financing to cover the cash flow requirements of the projects. These types of projects are [...]

This paper addresses the use of heuristic optimization algorithms to generate generally valid analytic equations for estimating the initial pressure drop of square and Dutch woven screens in polymer recycling. We present a mathematical description of the isothermal initial pressure drop of non-Newtonian polymer melt flows through woven screens without the need for numerical methods. We first performed numerical CFD simulations to create a set of 9,000 physically independent modeling set-ups as a basis for heuristic modeling. Then, we applied symbolic regression based on genetic programming to develop pecScreen models, achieving coefficients of determination [R.sup.2] > 0.9995. For verification of our models, we performed experiments using both virgin and slightly contaminated in-house and postindustrial recycling materials. The experimentally determined data are in good agreement with the approximation results, which yielded a coefficient of determination R2 of 0.926. Our modeling approach, the accuracy of which we have proven, allows fast and stable computational modeling of the initial pressure drop of polymer melt flows through woven screens. POLYM. ENG. SCI., 59:1105-1113, 2019. [C] 2019 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers., INTRODUCTION With the role and importance of plastics in our economy continuously growing in the past 50 years, the annual demand for plastics in Europe has steadily increased, reaching 49 [...]

This column is the first of a set that expands our previous discussions of the classical least squares (CLS) algorithm. Having found a new effect that can introduce a large error in calibration results, we extend our investigation of the effects of this phenomenon to calibrations using principal component regression (PCR) and partial least squares (PLS) that we were previously unable to do., A while back, we published a series of columns, and a formal paper, about classical least squares (CLS) analysis of liquid mixtures (1-15) to deal with and explain the use [...]

Water distribution networks (WDNs) are one of the most important elements of urban infrastructure and require large investment for construction. Design of WDNs is classified as a large combinatorial discrete nonlinear optimization problem. The main concerns associated with the optimization of such networks are the nonlinearity of the discharge-head loss relationships for pipes and the discrete nature of pipe sizes. Due to these issues, this problem is widely considered to be a benchmark problem for testing and evaluating the performance of nonlinear and heuristic optimization algorithms. This paper compares different techniques, all based on evolutionary algorithms (EAs), which yield optimal solutions for least-cost design of WDNs. All of these algorithms search for the global optimum starting from populations of solutions, rather than from a single solution, as in Newton-based search methods. They use different operators to improve the performance of many solutions over repeated iterations. Ten EAs, four of them for the first time, are applied to the design of three networks and their performance in terms of the least cost, under different stopping criteria, are evaluated. Statistical information for 20 executions of the ten algorithms is summarized, and Friedman tests are conducted. Results show that, for the two-loop benchmark network, the particle swarm optimization gravitational search and biology and bioinformatics global optimization algorithms efficiently converge to the global optimum, but perform poorly for large networks. In contrast, given a sufficient number of function evaluations, the covariance matrix adaptation evolution strategy and soccer league competition algorithm consistently converge to the global optimum, for large networks. Key words: evolutionary algorithms, genetic algorithm, water distribution networks, optimization. Les reseaux de distribution d'eau (RDE) sont l'un des elements les plus importants de l'infrastructure urbaine et leur construction necessite d'importants investissements. La conception des RDE est consideree comme un important probleme d'optimisation non lineaire combinatoire. Les principales preoccupations liees a l'optimisation de ces reseaux sont la nonlinearite des relations debit--perte de charge pour les tuyaux et la nature discrete des dimensions des conduites. En raison de ces difficultes, cette problematique est generalement consideree comme un probleme d'evaluation pour tester et evaluer les performances des algorithmes d'optimisation non lineaire et heuristique. Cet article compare differentes techniques, toutes basees sur des algorithmes evolutionnistes (AE), qui donnent des solutions optimales en matiere de conception de RDE a moindre cout. Tous ces algorithmes cherchent l'optimum global a partir de populations de solutions, plutot qu'a partir d'une solution unique, comme dans les methodes de recherche basees sur Newton. Ils utilisent differents operateurs pour ameliorer le rendement de nombreuses solutions au cours d'iterations repetees. Dix AE sont employes, dont quatre pour la premiere fois, a la conception de trois reseaux dont les performances en matiere de moindres couts, selon differents criteres d'arret, sont evaluees. Des informations statistiques pour 20 executions des 10 algorithmes sont resumees, et des tests de Friedman sont effectues. Les resultats montrent que, pour le reseau de comparaison en anneau double, les algorithmes d'optimisation gravitationnelle par essaim des particules et les algorithmes d'optimisation globale de la biologie et de la bio-informatique convergent efficacement vers l'optimum global, mais ne fonctionnent pas efficacement pour les grands reseaux. En revanche, avec un nombre suffisant devaluations fonctionnelles, les algorithmes strategie devolution de l'adaptation de la matrice de covariance et de competition de ligue de soccer convergent systematiquement vers l'optimum global, pour les grands reseaux. [Traduit par la Redaction] Mots-cles: algorithme evolutionniste, algorithme genetique, reseaux de distribution d'eau, optimisation., Introduction Evolutionary algorithms (EAs) are becoming increasingly popular for their use in solving engineering decision problems and in practical applications such as calibration, because they: (i) are based on rather [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2010.05.002 Byline: Farhad Gh. Khodaei (a), Javad Nourinia (a), Changiz Ghobadi (b) Keywords: Adaptive beamforming; Eigenvalue; Smart antennas; CDMA Abstract: In this paper, a novel adaptive beamforming algorithm has been proposed which can be used for tracking the subscribers of a smart antenna in a wide angle spread environment. It can be adapted for arbitrary variations in both eigenvalues and eigenvectors of the autocorrelation matrix of received signal which is mostly the case for moving subscribers' environment. Moreover, it uses one adaptive module which is less than two adaptive modules of previous works and leads to a high speed at least two times more than previous works. Author Affiliation: (a) No. 16, Laleh Alley, Ranjbar Alley, Pasdaran Street, Maragheh City, East Azarbayjan State 55167-13846, Iran (b) Urmia university, Urmia, Iran Article History: Received 15 June 2009; Revised 24 March 2010; Accepted 3 May 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2010.05.004 Byline: Tae-Wuk Bae (a), Byoung-Ik Kim (a), Young-Choon Kim (b), Kyu-Ik Sohng (a) Keywords: Infrared sequences; Small target detection; Cross product; Temporal profile; Hypothesis testing Abstract: This paper presents a new small target detection method using cross product of temporal pixels based on temporal profiles in infrared (IR) image sequences. Temporal characteristics of small targets and various backgrounds are different. A new algorithm classifies target pixels and background pixels through hypothesis testing using the cross product of pixels on temporal profile and predicts the temporal backgrounds based on the results. Small target pixels are detected by subtracting the predicted temporal background profile from the original temporal profile. For performance comparison between the proposed method and the conventional methods, the receiver operating characteristics (ROC) curves were computed experimentally. Experimental results show that the proposed algorithm has better discrimination of target and clutter pixels and lower false alarm rates than conventional methods. Author Affiliation: (a) School of Electrical Engineering and Computer Science, Kyungpook National University, South Korea (b) Dept. of Information and Communication Engineering, Youngdong University, South Korea Article History: Received 6 December 2009; Accepted 17 May 2010 Article Note: (footnote) [star] Reviews processed and proposed for publication to the Editor-in-Chief by Associate Editor Dr. F. Sahin.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2010.03.009 Byline: Ramin Tajallipour, Khan A. Wahid Abstract: The paper presents a fast algorithm to efficiently compute radix-10 logarithm of a decimal number. The algorithm uses a 32-bit floating-point arithmetic, and is based on a digit-by-digit iterative computation that does not require look-up tables, curve fitting, decimal-binary conversion, or division operations; the number of iterations depends on the precision defined by the user. Two numerical examples are shown for the purpose of illustration. The algorithm produces very accurate result with a maximum absolute error of 0.267x10.sup.-5 for a 32-bit precision. When implemented on to the Xilinx VirtexII FPGA, the pipelined architecture costs only 2632 logic cells, runs at a maximum frequency of 53.5MHz, and consumes 117mW of power. The design is very suitable for timing and accuracy critical applications and compliant with IEEE754-2008 standard. Author Affiliation: Dept. of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Article History: Received 2 July 2009; Revised 30 January 2010; Accepted 31 March 2010 Article Note: (footnote) [star] Reviews processed and proposed for publication to the Editor-in-Chief by Associate Editor Dr. F. Balasa.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2009.12.015 Byline: A.Y. Al-nahari (a), S.A. El-Dolil (b), M.I. Desouky (b), F.E. Abd El-samie (b) Keywords: Call admission control; Load control; Power control; WCDMA Abstract: Wideband code division multiple access (WCDMA) systems are interference-limited. When a WCDMA system operates at nearly full capacity, admitting a new user may affect the stability of the system. Therefore, the proper call admission control (CAC) is crucial and should balance between quality of service (QoS) requirements for the new user as well as for the existing users and the required high capacity. In this paper, we investigate this trade-off in the uplink direction using a power-based multi-cell admission control (MC-AC) algorithm. Multimedia services are considered with different QoS requirements in this algorithm. Different traffic scenarios are also considered. Simulation results reveal that the proposed MC-AC algorithm has many advantages over single-cell admission control (SC-AC) in terms of the overall stability of the system and the total system throughput. Author Affiliation: (a) Department of Electronics, Faculty of Engineering and Architecture, Ibb University, Ibb, Yemen (b) Department of Electronics and Electrical Communications, Faculty of Electronic Engineering, Menoufia University, Menouf, Egypt Article History: Received 12 September 2008; Revised 27 September 2009; Accepted 31 December 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2009.03.008 Byline: Ali Chamam, Samuel Pierre Keywords: Wireless sensor networks; Clustering; Network lifetime; Distributed; Energy efficiency Abstract: Minimizing energy dissipation and maximizing network lifetime are among the central concerns when designing applications and protocols for sensor networks. Clustering has been proven to be energy-efficient in sensor networks since data routing and relaying are only operated by cluster heads. Besides, cluster heads can process, filter and aggregate data sent by cluster members, thus reducing network load and alleviating the bandwidth. In this paper, we propose a novel distributed clustering algorithm where cluster heads are elected following a three-way message exchange between each sensor and its neighbors. Sensor's eligibility to be elected cluster head is based on its residual energy and its degree. Our protocol has a message exchange complexity of O(1) and a worst-case convergence time complexity of O(N). Simulations show that our algorithm outperforms EESH, one of the most recently published distributed clustering algorithms, in terms of network lifetime and ratio of elected cluster heads. Author Affiliation: Department of Computer Engineering, Ecole Polytechnique of Montreal, C.P. 6079, succ. Centre-Ville, Montreal (QC), Canada H3C 3A7

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2009.04.005 Byline: Xiang-Yang Wang (a)(b), Yi-Ping Yang (b), Hong-Ying Yang (b) Keywords: Image watermarking; Desynchronization attacks; Multi-scale Harris detector; Wavelet moments Abstract: Desynchronization attack is known as one of the most difficult attacks to resist, which can desynchronize the location of the watermark and hence causes incorrect watermark detection. It is a challenging work to design a robust image watermarking scheme against desynchronization attacks. Based on multi-scale Harris detector and wavelet moment theory, we propose a new content based image watermarking algorithm with low computational complexity, good visual quality and reasonable resistance toward desynchronization attacks in this paper. Firstly, the steady image feature points are extracted from the origin host by using multi-scale Harris detector, and the local feature regions (LFRs) are constructed adaptively according to the feature scale theory. Then, the LFRs are image normalized, and significant regions are obtained from the normalized LFRs by utilizing the invariant centroid theory. Finally, the digital watermark is embedded into the LFRs by modifying wavelet moment invariants of the significant regions. By binding the watermark with the geometrically invariant image features, the watermark detection can be done without synchronization error. Experimental results show that the proposed image watermarking is not only invisible and robust against common image processing operations as sharpening, noise adding, and JPEG compression etc, but also robust against the desynchronization attacks such as rotation, translation, scaling, row or column removal, cropping, and local random bend etc. Author Affiliation: (a) State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876, China (b) School of Computer and Information Technology, Liaoning Normal University, Dalian 116029, China Article History: Received 12 September 2008; Revised 15 April 2009; Accepted 23 April 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.11.022 Byline: Xiaomin Zhu, Peizhong Lu Keywords: Scheduling; Heterogeneous clusters; Real-time; Security-critical; Heuristic Abstract: Nowadays, increasing attention has been directed towards the issue of security service for real-time applications with security requirements on clusters. However, the study of integrating security demands of real-time applications into scheduling is rare. In this paper, we propose a novel two-phase scheduling strategy TPSS which takes timing constraints and security needs into consideration for security-critical real-time applications on heterogeneous clusters. In the first-phase, a novel algorithm DSRF is proposed to schedule real-time tasks. When the system is in heavy burden, DSRF is able to degrade the security levels of new tasks and tasks waiting in local queues so as to enhance guarantee ratio. On the contrary, when the system is in light burden, DSRF is capable of employing slack time to improve the security quality of new tasks and adequately utilize the system resource. The minimal security level can guarantee the system security, and higher security level is able to make the system more secure. In the second-phase, a new algorithm FMSL is proposed to minimize the difference of security levels of accepted tasks and further improve the security levels of accepted tasks on the whole, which degrades the probability of the applications being attacked. We compare TPSS, DSRF, SAEDF and RF by extensive simulations. The experimental results indicate that TPSS significantly improves the flexibility of scheduling and outperforms other algorithms. Author Affiliation: School of Computer Science, Fudan University, No. 220 Handan Road, Shanghai 200433, PR China

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.11.019 Byline: Ling Wang (a), Hui Song (a), Yingtao Jiang (b), Lihong Zhang (c) Keywords: Interconnect; Mesh; Routing; Network-on-chip; SoC Abstract: In this paper, we present a routing algorithm that combines the shortest path routing and adaptive routing schemes for NoCs. In specific, routing follows the shortest path to ensure low latency and low energy consumption. This routing scheme requires routing information be stored in a series of routing tables created at the routers along the routing path from the source to the destination. To reduce the exploration space and timing cost for selecting the routing path, a routing list and routing table for each node are created off-line. Routing table is updated on-line to reflect the dynamic change of the network status to avoid network congestion. To alleviate the high hardware implementation cost associated with the routing tables, a method to help reduce the size of the routing tables is also introduced. Compared to the existing routing algorithms, the experimental results have confirmed that the proposed algorithm has better performance in terms of routing latency and power consumption. Author Affiliation: (a) Department of Computer Science and Technology, Harbin Institute of Technology, #715, Harbin 150001, PR China (b) Department of Electrical and Computer Engineering, University of Nevada, Las Vegas, USA (c) Electrical and Computer Engineering, Faculty of Engineering and Applied Science, Memorial University of Newfoundland, Canada

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2009.02.006 Byline: Kanyapat Watcharasitthiwat, Paramote Wardkein Keywords: Ant colony optimization; Genetic algorithm; Reliability optimization; Tabu search algorithm; Topology network design Abstract: Network design problem is a well-known NP-hard problem which involves the selection of a subset of possible links or a network topology in order to minimize the network cost subjected to the reliability constraint. To overcome the problem, this paper proposes a new efficiency algorithm based on the conventional ant colony optimization (ACO) to solve the communication network design when considering both economics and reliability. The proposed method is called improved ant colony optimizations (IACO) which introduces two addition techniques in order to improve the search process, i.e. neighborhood search and re-initialization process. To show its efficiency, IACO is applied to test with three different topology network systems and its results are compared with those obtained results from the conventional approaches, i.e. genetic algorithm (GA), tabu search algorithm (TSA) and ACO. Simulation results, obtained these test problems with various constraints, shown that the proposed approach is superior to the conventional algorithms both solution quality and computational time. Author Affiliation: Department of Telecommunication Engineering, Faculty of Engineering, King Mongkut's Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520, Thailand Article History: Received 11 January 2007; Revised 7 January 2009; Accepted 10 February 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.08.002 Byline: Mani Ranjbar, Shohreh Kasaei Keywords: Spatial error concealment; Image completion; Inpainting; Exemplar-based error concealment; Real-time concealment; Context-dependent splitting; Video compression Abstract: In this paper, the problem of spatial error concealment for real-time applications is addressed. The proposed method can be categorized in exemplar-based error concealment approaches. In this category, a patch of corrupted pixels are replaced by another patch of the image that contains correct pixels. For splitting the erroneous block to different patches, a novel context-dependent exemplar-based algorithm based on a previously proposed segmentation method is proposed. The capability of the proposed method for concealment in diverse image regions is depicted. Our detailed conducted experiments show that the proposed method outperforms the state-of-the-art spatial error concealment methods in terms of output quality. Author Affiliation: Department of Computer Engineering, Sharif University of Technology, Tehran 11155-9517, Iran

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.11.004 Byline: Khaled Mayyas Keywords: Adaptive filters; Low complexity algorithms; Stereophonic acoustic echo cancellation Abstract: Stereophonic acoustic echo cancellation (SAEC) has brought up recently much attention and found a viable place in a number of hands-free applications. In this paper, we propose an LMS-type algorithm for SAEC based on decomposing the long adaptive filter of each channel of the SAEC system into smaller subfilters. We further reduce the complexity of the algorithm by employing the selective coefficient update (SCU) method in each subfilter. This leads to a significant improvement in the convergence rate of the algorithm with low computational overhead. However, the algorithm has a high final mean-square error (MSE) at steady-state that increases as number of subfilters increases. A combined-error algorithm is presented that achieves fast convergence without compromising the steady state error level. Simulations demonstrate the convergence speed advantages of the combined-error algorithm. Author Affiliation: Department of Electrical Engineering, Jordan University of Science and Technology, P.O. Box 3030, Irbid 221 10, Jordan Article History: Received 30 July 2007; Accepted 7 November 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.06.004 Byline: Amir Moradi (a), Mohammad Taghi Manzuri Shalmani (a), Mahmoud Salmasizadeh (b) Keywords: Side-channel attacks; DPA; DTL; Transition signaling; Countermeasure Abstract: In this paper, a new logic style is proposed to be used in the implementation of cryptographic algorithms. The aim of this approach is to counteract power analysis attacks. The proposed technique is based on the transition signaling. In dual-rail transition logic, one-bit value is transmitted by a transition on the proper signal of a couple of wires. According to this concept, converter units and logic gates are defined; it is proposed to use flip-flops to build DTL alternative parts. Although the usage of flip-flops leads to increase the required area, experimental results show that the power consumption of DTL circuits depends on unpredictable initial state of T-flip-flops. In other words, DTL randomizes the power consumption without using random number/mask generators while its delay time is reasonable in comparison with other logic styles. The difference of mean traces and the simulated attacks show that the power consumption of DTL gates does not correlate with the input/output values. Author Affiliation: (a) Department of Computer Engineering, Sharif University of Technology, Tehran, Iran (b) Electronic Research Center, Sharif University of Technology, Tehran, Iran Article Note: (footnote) [star] This project is partially supported by Iran National Science Foundation and Iran Telecommunication Research Center.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.06.003 Byline: Santi P. Maity (a), Malay K. Kundu (b), Seba Maity (c) Keywords: Authentication; Digital watermarking; Fast Walsh transform; FPGA; QoS; VLSI Abstract: Spread spectrum (SS) watermarking for multimedia signal becomes appealing due to its high robustness attribute and is used widely for various applications. Some of these applications essentially demand development of low cost algorithms so that they can be used for real time services such as broadcast monitoring, security in communication etc. In recent time one popular non-conventional application of digital watermarking becomes promising that assesses blindly the QoS (quality of services) of the multimedia services which is expected to be offered by the future generation mobile radio network. Majority of the existing SS watermarking schemes suffer from high computation cost and complexity leading to the difficulty for real time implementation and limits their usage for the above mentioned applications. This paper proposes fast Walsh transform (FWT) based SS image watermarking scheme that serves the dual purposes of authentication in data transmission as well as QoS assessment for digital media through dynamic estimation of the wireless channel condition. Fast Walsh transform offers low computation cost for implementation, smaller change in image (multimedia signal) information due to data embedding and ease of hardware realization. VLSI implementation using field programmable gate array (FPGA) has been developed to make it suitable for real time implementation. Author Affiliation: (a) Department of Information Technology, Bengal Engineering and Science University, Shibpur P.O. Botanic Garden, Howrah 711 103, India (b) Center for Soft Computing Research and Machine Intelligence Unit, Indian Statistical Institute, 203, B.T. Road, Kolkata 700 108, India (c) Department of EI and ECE, College of Engineering and Management, Kolaghat, P.O. Mecheda, Midnapur East 721 171, India

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.06.008 Byline: Radha Guha, Nader Bagherzadeh, Pai Chou Keywords: HW/SW co-design; Streaming applications; Application convergence; Hardware resource management; Task placement; Partitioning and scheduling algorithm Abstract: There are many design challenges in the hardware-software co-design approach for performance improvement of data-intensive streaming applications with a general-purpose microprocessor and a hardware accelerator. These design challenges are mainly to prevent hardware area fragmentation to increase resource utilization, to reduce hardware reconfiguration cost and to partition and schedule the tasks between the microprocessor and the hardware accelerator efficiently for performance improvement and power savings of the applications. In this paper a modular and block based hardware configuration architecture named memory-aware run-time reconfigurable embedded system (MARTRES) is proposed for efficient resource management and performance improvement of streaming applications. Subsequently we design a task placement algorithm named hierarchical best fit ascending (HBFA) algorithm to prove that MARTRES configuration architecture is very efficient in increased resource utilization and flexible in task mapping and power savings. The time complexity of HBFA algorithm is reduced to O(n) compared to traditional Best Fit (BF) algorithm's time complexity of O(n.sup.2), when the quality of the placement solution by HBFA is better than that of BF algorithm. Finally we design an efficient task partitioning and scheduling algorithm named balanced partitioned and placement-aware partitioning and scheduling algorithm (BPASA). In BPASA we exploit the temporal parallelism in streaming applications to reduce reconfiguration cost of the hardware, while keeping in mind the required throughput of the output data. We balance the exploitation of spatial parallelism and temporal parallelism in streaming applications by considering the reconfiguration cost vs. the data transfer cost. The scheduler refers to the HBFA placement algorithm to check whether contiguous area on FPGA is available before scheduling the task for HW or for SW. Author Affiliation: EECS Department of UC, Irvine, United States

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.06.014 Byline: Behnam Ghavami, Hossein Pedram, Mehrdad Najibi Keywords: Cryptography; Side channel attack; Asynchronous design; Low power; QDI Abstract: Regarding the significant mathematical immunity of recent cryptographic algorithms, attacks considering the physical aspects of these algorithms, known as side channel attacks, have received much of interest. Today, it is quite clear that asynchronous circuits possess considerable inherent countermeasure capabilities against side channel attacks, and therefore they are more immune for cryptographic systems compared to synchronous design. However, due to lack of automatic synthesis and optimization tools for these circuits, implementation of secure asynchronous circuits encounters many difficulties. In this paper, a fully automated secure design flow and a set of secure library cells resistant to power analysis and fault injection attacks are introduced for quasi delay insensitive asynchronous circuits. In the proposed flow, a high-level description of the system is received in Verilog format powered by some special macros, and then the corresponding specification will be decomposed into smaller circuits directly mappable to predefined circuit templates. With the use of a special standard-cell library, the final circuit is resistive to differential power analysis on faulty hardware attack. We suggest a restructuring on the conditional statements in the high-level description of the circuit which leads to a considerable optimization in power consumption after the decomposition of the system. To verify the efficiency of our presented design flow, we implemented data encryption standard (DES) and advanced encryption standard (AES) algorithms, and we showed 23% less power consumption compared to the existing data driven decomposition asynchronous synthesis method. Also, these implementations are three times faster than the synchronous implementations on average, in TSMC 0.18[mu]m technology. Author Affiliation: Computer Engineering Department, Amirkabir University of Technology, Tehran, Iran

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.09.007 Byline: Baodong Qin (a), Ming Li (b)(c), Fanyu Kong (b)(c), Daxing Li (b)(c) Keywords: Non-adjacent form; Left-to-right recoding; Integer recoding; Pairing based cryptosystems; Signed radix-r representation Abstract: Recently, signed-digit radix-r (r[greater than or equal to]2) representation is used to speed up the scalar multiplication of pairing based cryptosystems. One such representation is wrNAF proposed by Takagi et al. at the international conference on information security 2004 (ISC 2004). This representation is obtained from right to left. In this paper, we present a new signed-digit radix-r representation with the same average weight, that is r-1/w(r-1)+1 as the wrNAF. The new representation uses the same digits as the wrNAF but has the advantage that it can be deduced using a left-to-right algorithm. Further, we show that like the wrNAF, the new representation has a minimal number of non-zero digits. Interleaved with the left-to-right scalar multiplication, the new representation can reduce both the time and space complexity of the computation compared to the right-to-left wrNAF. Author Affiliation: (a) College of Computer Science and Technology, Southwest University of Science and Technology, 59 Qinglong Road, Mianyang 621010, Sichuan, PR China (b) Institute of Network Security, Shandong University, 27 Shanda Nanlu Road, Jinan 250100, Shandong, PR China (c) Key Laboratory of Cryptographic Technology and Information Security, 27 Shanda Nanlu Road, Jinan 250100, Shandong, PR China Article History: Received 4 January 2008; Accepted 18 September 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.09.001 Byline: Ali A. Kanso Keywords: Cryptography; Security; Stream ciphers; Linear feedback shift registers; Shrinking generator Abstract: The need for wireless communication systems has increased rapidly in the past few years and wireless communication has become more convenient in business and society. However, the air interface is vulnerable to eavesdropping, hence encryption in wireless communication systems is a necessity to keep sensitive information confidential and to prevent fraud. Furthermore, wireless devices such as Bluetooth devices and mobile phones require an encryption algorithm that is secure, fast and simple to implement. There are several cryptosystems for stream cipher applications such as A5/x used in GSM mobile communications. However, A5/x are vulnerable to cryptanalytic attacks. In this paper, a new clock-controlled cryptosystem intended for hardware implementation is proposed. The design has attractive properties such as simplicity and scalability. The cryptographical properties including period, balancedness, linear complexity and probability distribution are analyzed. The design provides the basic security requirements, and is resistant to known cryptanalytic attacks. It is shown that the irregular clocking introduced provides a certain level of strengthened security against several cryptanalytic attacks. These properties enhance its use as a suitable cryptosystem for stream cipher applications. Author Affiliation: Department of Mathematics and Computer Science, College of Science, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait Article History: Received 24 December 2007; Accepted 3 September 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.07.001 Byline: Cihan Topal, Cuneyt Akinlar Keywords: P2P; IPv4+4; LSRR; STUN; SIP Abstract: The current structure of the Internet, with hosts behind network address translation (NAT) boxes, causes well-known problems for P2P applications. There are several proposals, e.g., STUN, UPnP, MIDCOM, TURN among others, to enable P2P UDP communication for nodes behind NAT boxes, but each technique offers a partial solution that works in special limited cases and fails in others. In this paper, we present a framework based on the use of IPv4+4 addresses and the standard IPv4 Loose Source Record Route (LSRR) option that offers a complete solution to the secure seamless P2P UDP communication problem. Our proposal requires no changes whatsoever to end-host protocol stacks and Internet routers. The only requirement is a simple upgrade of border routers with a new LSRR-based packet forwarding algorithm for the P2P UDP traffic. We detail our implementation of a Linux-based border router that runs the proposed forwarding algorithm, and describe how applications requiring P2P UDP communication such as Voice over IP (VoIP) using SIP can benefit from our framework. Author Affiliation: Anadolu University, Department of Computer Engineering, 2 Eylul Kampusu, 26470 Eskisehir, Turkey Article History: Received 28 January 2008; Accepted 17 July 2008 Article Note: (footnote) [star] This work is partially supported by Turkish Science and Technology Research Institute (TUBITAK) Grant 107E166.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2007.12.004 Byline: Arash Dana (a), Ahmad Khadem Zadeh (b), Seyed Ali Sadat Noori (a) Keywords: Mobile ad hoc networks; Reliability; Routing; Neural networks Abstract: Topological changes in mobile ad hoc networks frequently render routing paths unusable. Such recurrent path failures have detrimental effects on quality of service. A suitable technique for eliminating this problem is to use multiple backup paths between the source and the destination in the network. Most of the proposed on-demand routing protocols however, build and rely on single route for each data session. Whenever there is a link disconnection on the active route, the routing protocol must perform a path recovery process. This paper proposes an effective and efficient protocol for backup and disjoint path set in an ad hoc wireless network. This protocol converges into a highly reliable path set very fast with no message exchange overhead. The paths selection according to this algorithm is beneficial for mobile ad hoc networks, since it produces a set of backup paths with much higher reliability. Simulations are conducted to evaluate the performance of our algorithm in terms of route numbers in the path set and its reliability. In order to acquire link reliability estimates, we use link expiration time (LET) between each two nodes. In another experiment, we save the LET of entire links in the ad hoc network during a specific time period, then use them as a data base for predicting the probability of proper operation of links. Links reliability obtains from LET. Prediction is done by using a multi-layer perceptron (MLP) network which is trained with error back-propagation error algorithm. Experimental results show that the MLP net can be a good choice to predict the reliability of the links between the mobile nodes with more accuracy. Author Affiliation: (a) Department of Electrical Engineering, Central Tehran Branch, Islamic Azad University, Iran (b) Education and International Scientific Cooperation Department, Iran Telecommunication Research Center, Iran Article History: Received 5 September 2006; Accepted 17 December 2007

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2008.02.001 Byline: Marc St-Hilaire (a), Steven Chamberland (b), Samuel Pierre (b) Keywords: Third generation (3G) mobile networks; Universal mobile telecommunications system (UMTS); Network planning; Global approach; Metaheuristic; Tabu search (TS) Abstract: In this paper, we propose a tabu search (TS) algorithm for the global planning problem of third generation (3G) universal mobile telecommunications system (UMTS) networks. This problem is composed of three NP-hard subproblems: the cell, the access network and the core network planning subproblems. Therefore, the global planning problem consists in selecting the number, the location and the type of network nodes (including the base stations, the radio network controllers, the mobile switching centers and the serving GPRS (General Packet Radio Service) support nodes) as well as the interconnections between them. After describing our metaheuristic, a systematic set of experiments is designed to assess its performance. The results show that quasi-optimal solutions can be obtained with the proposed approach. Author Affiliation: (a) Department of Systems and Computer Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6 (b) Department of Computer Engineering, Ecole Polytechnique de Montreal, C.P. 6079, Succ. Centre-Ville, Montreal, Quebec, Canada H3C 3A7 Article History: Received 24 August 2006; Accepted 2 February 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2007.12.003 Byline: Ricardo Lima, Damian Quiroga, Claudio Reineri, Fernando Magnago Keywords: Power quality; Wavelet transform; Control center applications Abstract: This paper presents a novel concept for power quality hardware and software architecture. Software tools related to detection, classification and characterization of power quality events can be integrated into a Distribution Control Center in which the interconnection between different subsystems is being carried out through the Internet allowing flexibility to the system. This system is implemented using wavelet analysis applied in all proposed algorithms. Different power quality events are taken as examples to illustrate the capabilities of the proposed method. The obtained results reveal that the proposed architecture is feasible to be implemented as an integral part of a control center system. The proposed system has the property of fast and accurate detection and classification of any power quality disturbance event and introduces a new PQ index determination that allows characterizing any type of disturbance including the non-periodic signals. Author Affiliation: Universidad Nacional de Rio Cuarto, Campus Universitario. Ruta 36, Km 601 Cordoba, Argentina Article History: Received 29 March 2006; Accepted 12 December 2007

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2007.11.003 Byline: Tomas Balderas-Contreras, Rene Cumplido, Claudia Feregrino-Uribe Keywords: Cryptography; Block cipher; KASUMI; Hardware implementation; RISC Processors Abstract: Modern cellular networks allow users to transmit information at high data rates, have access to IP-based networks deployed around the world, and access to sophisticated services. In this context, not only is it necessary to develop new radio interface technologies and improve existing core networks to reach success, but guaranteeing confidentiality and integrity during transmission is a must. The KASUMI block cipher lies at the core of both the f8 data confidentiality algorithm and the f9 data integrity algorithm for Universal Mobile Telecommunications System networks. KASUMI implementations must reach high performance and have low power consumption in order to be adequate for network components. This paper describes a specialized processor core designed to efficiently perform the KASUMI algorithm. Experimental results show two orders of magnitude performance improvement over software only based implementations. We describe the used design technique that can also be applied to implement other Feistel-like ciphering algorithms. The proposed architecture was implemented on a FPGA, results are presented and discussed. Author Affiliation: Computer Science Department National Institute for Astrophysics, Optics and Electronics, INAOE Luis E. Erro 1, Tonantzintla, Puebla 72840, Mexico Article History: Received 8 January 2007; Accepted 27 November 2007

The economic design of control charts and the optimization of preventive maintenance policies have separately received a tremendous amount of attention in the quality and reliability literature over the years in an attempt to reduce the costs associated with operating manufacturing processes. Not until recently has the proposal been made to integrate these two fields and utilize the relationship between quality and equipment performance to improve the productivity of a manufacturing process. In this paper, we extend the initial preliminary investigation of this idea of using an [bar.X] chart in conjunction with an age-replacement preventive maintenance policy. We formulate a partially observable, discrete-time Markov decision process in order to obtain the near-optimal combined preventive maintenance/statistical process control policy that minimizes the costs associated with maintenance, sampling, and poor quality. We develop transition probabilities for the various states of the infinite horizon problem and a solution algorithm for finding the best policy in polynomial time by finding a control limit on the sampling policy. We also perform sensitivity analysis on the decision variables for each of the various input parameters. It is shown that in every case a combined PM and SPC policy is the most cost efficient. Keywords: Quality control, control limit, partially observable Markov decision processes, preventive maintenance, 1. Introduction The economic design of control charts has recently received a tremendous amount of attention in the statistical process control literature. Designing control charts with an economic objective refers [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2007.05.005 Byline: K. Sakiyama, L. Batina, B. Preneel, I. Verbauwhede Keywords: HW/SW co-design; RSA; ECC; FPGA implementation; GF(p) operations; GEZEL Abstract: It is a challenge to implement large word length public-key algorithms on embedded systems. Examples are smartcards, RF-ID tags and mobile terminals. This paper presents a HW/SW co-design solution for RSA and Elliptic Curve Cryptography (ECC) over GF(p) on a 12MHz 8-bit 8051 micro-controller. The hardware coprocessor has a Modular Arithmetic Logic Unit (MALU) of which the digit size (d) is variable. It can be adapted to the speed and bandwidth of the micro-controller to which it is connected. The HW/SW co-design space exploration is based on the GEZEL system-level design environment. It allows the designer to find the best performance-area combination for the digit size. As a case study of an FPGA prototyping, 160-bit ECC over GF(p) (ECC-160p) was implemented on Xilinx Virtex-II PRO (XC2VP30). The results show that one point multiplication takes only 130ms including all communications between the 8051 and the coprocessor. The performance is 40 times faster than the most optimized SW implementation on a small CPU in literature. This is achieved by the HW/SW co-design exploration in order to find the optimized digit size of the MALU. On the other hand, the design of ECC-160p maintains a high level of flexibility by using coprocessor instructions. Our proposed architecture proves that HW/SW co-design provides a high performance close to ASIC solutions with a flexible feature of SW even on a small CPU. Author Affiliation: Katholieke Universiteit Leuven, Department Electrical Engineering - ESAT/SCD-COSIC Kasteelpark Arenberg 10, B-3001 Leuven-Heverlee, Belgium

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2007.05.002 Byline: Maurice Keller, Robert Ronan, William Marnane, Colin Murphy Keywords: Tate pairing; Cryptography; Hardware architecture; BKLS/GHS algorithm Abstract: In this paper two different approaches to the design of a reconfigurable Tate pairing hardware accelerator are presented. The first uses macro components based on a large, fixed number of underlying Galois Field arithmetic units in parallel to minimise the computation time. The second is an area efficient approach based on a small, variable number of underlying components. Both architectures are prototyped on an FPGA. Timing results for each architecture with various different design parameters are presented. Author Affiliation: Department of Electrical and Electronic Engineering, University College Cork, Cork City, Ireland

Abstract This paper considers the problem of the dynamic processing of large amounts of sparse three-dimensional data. It is assumed that computations are performed in a neighborhood defined around each [...]

This paper investigates learning causal relationships from the extensive datasets that are becoming increasingly available in manufacturing systems. A causal modeling approach is proposed to improve an existing causal discovery algorithm by integrating manufacturing domain knowledge with the algorithm. The approach is demonstrated by discovering the causal relationships among the product quality and process variables in a rolling process. When allied with engineering interpretations, the results can be used to facilitate rolling process control. Keywords: Bayesian network, process control, knowledge discovery, causal modeling, rolling process, 1. Introduction Rapid advances in sensing and computing technologies have allowed numerous sensors to be imbedded in manufacturing systems to collect on-line production data. Analysis of the extensive datasets could [...]

In this paper, the mechanical properties of erythrocytes were studied numerically based upon the mechanical model originally developed by Pamplona and Calladine (ASME J. Biomech. Eng., 115, p. 149, 1993) for liposomes. The case under study is the erythrocyte stretched by a pair of laser beams in opposite directions within buffer solutions. The study aims to elucidate the effect of radiation pressure from the optical laser because up to now little is known about its influence on the cell deformation. Following an earlier study by Guck et al. (Phys. Rev. Lett., 84, p. 5451, 2000; Biophys. J., 81, p. 767, 2001), the empirical results of the radiation pressure were introduced and imposed on the cell surface to simulate the real experimental situation. In addition, an algorithm is specially designed to implement the simulation. For better understanding of the radiation pressure on the cell deformation, a large number of simulations were conducted for different properties of cell membrane. Results are first discussed parametrically and then evaluated by comparing with the experimental data reported by Guck et al. An optimization approach through minimizing the errors between experimental and numerical data is used to determine the optimal values of membrane properties. The results showed that an average shear stiffness around 4.611 x 10-6 [Nm.sup.-1], when the nondimensional ratio of shear modulus to bending modulus ranges from 10 to 300. These values are in a good agreement with those reported in literature. [DOI: 10.1115/1.2354204] Keywords: erythrocyte, cell membrane, Taylor deformation parameter, axisymmetry

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2006.01.024 Byline: Chin-Chen Chang (a), Yeu-Pong Lai (b) Keywords: Chinese Remainder Theorem; Residue Number System; Euclidean algorithm; Montgomery algorithm; Division-free Abstract: In recent years, the conversion of residue numbers to a binary integer has been intensively studied. The Chinese Remainder Theorem (CRT) is a solution to this conversion problem of a number to the Residue Number System with a general moduli set. This paper presents a new division-free conversion approach for the conversion of residue numbers to a binary integer. The algorithm differs from others employing a great number of division instructions by using shift instructions instead. These simple instructions keep the power consumption lower. This algorithm can also be implemented with a lookup table or upon a vector machine. Both make the conversion process efficient. This division-free algorithm employs the concept of Montgomery multiplication algorithm. There are two variations of Montgomery algorithm proposed, which are algorithms MMA and IMA. The algorithm MMA is to transform the input number into the output presentation of Montgomery algorithm. Algorithm IMA is therefore inverse the computation of Montgomery algorithm to obtain the multiplicand. These two algorithms are in the complexity of O(n), where n is alog.sub.2 q.sub.i a. q.sub.i is a modulus. The proposed algorithm for converting the residues to a binary integer therefore runs on O(n xlog m) times on O(m) processors. There are O(log m) iterations of O(n) complexity. Compared with the traditional conversion algorithm, the advantages of this proposed algorithm are not only in employing simpler operations but also in performing fewer iterations. Author Affiliation: (a) Department of Information Engineering and Computer Science, Feng Chia University, Taichung 40724, Taiwan, ROC (b) Department of Computer Science and Information Engineering, Chung Cheng Institute of Technology, National Defense University, Tauyuan 335, Taiwan, ROC Article History: Received 4 April 2002; Accepted 17 January 2006

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2005.12.001 Byline: Hao Yin (a), Feng Qiu (a), Chuang Lin (a), Geyong Min (b), Xiaowen Chu (c) Keywords: Security; Video multicast; Data embedding; Media-dependent approach Abstract: The secure distribution and maintenance of key information are essential for controlling access to video multicast systems. Unlike the conventional approaches using a dedicated channel independent of the video stream, this paper proposes a novel data embedding scheme, which we refer to as SMDE (statistical modulation data embedding), to support the media-dependent approach that exploits data-dependent channel to transmit and maintain key information. Using embedded data to convey key information is able to achieve added security and reduce bandwidth resource consumption. To this end, we present some new algorithms to embed key messages. By adopting the statistical properties of host video signal, new coding approach for embedded data, and error control algorithm, the proposed SMDE scheme can provide error resilience, transparence for adaptation mechanism, high accuracy of detecting embedded data and real-time processing capability for video applications. These advantages have been demonstrated by the extensive experimental results. Author Affiliation: (a) Department of Computer Science, Tsinghua University, 100084 Beijing, China (b) Department of Computing, University of Bradford, Bradford BD7 1DP, UK (c) Department of Computer Science, Hong Kong Baptist University, Kowloon Tong, Hong Kong Article History: Received 8 December 2004; Accepted 1 December 2005 Article Note: (footnote) [star] This work is supported by the National Natural Science Foundation of China (Nos. 60372019, 90104002, 60173012 and 60473086), the Projects of Development Plan of the State High Technology Research (No. 2001AA112080).

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2006.01.006 Byline: S.-E. Elayoubi, B. Fourestie, S. Ben Jamaa Keywords: Performance evaluation; Dynamic simulation; Mobile networks; QoS; Variance reduction; Convergence diagnostic; Interference matrices Abstract: This paper presents statistical methods to enhance dynamic simulations in mobile networks. The aim is to perform reliable (unbiased) and fast evaluation of QoS indicators such as blocking and dropping rates. To do so, we adopt a trajectory splitting (TS) method that splits the path of the simulated stochastic process into multiple copies for determined configurations, thus focusing on configurations for which communication problems are likely to occur. We show that this method significantly reduces the variance of the estimators of both blocking and dropping probabilities, and hence reduces simulation times for the same precision. In a real network dynamic simulation, we propose an algorithm that automatically checks that the network has reached its steady state distribution and eliminates the bias due to the initial stabilization samples. We then isolate stations of interest with their most interfering neighbors and show that applying TS to these regions of interest leads to a very significant reduction of the simulation times. Author Affiliation: France Telecom R&D, 38-40 rue du General Leclerc, 92130 Issy Les Moulineaux, France

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2006.01.005 Byline: Maode Ma, Qichao Zhu Keywords: CDMA wireless networks; Integrated service; Medium access control protocols; DQRAP/CDMA; Collision resolution Abstract: With rapid development of wireless technology, more and more applications can be served by wireless networks. To provide integrated service over wireless networks has become a very important issue in the design of wireless networks. In this paper, we propose a new MAC protocol with scheduling algorithms to provide integrated service for CDMA based wireless networks. This protocol evolves from the distributed queuing random access protocol for CDMA wireless network (DQRAP/CDMA). The proposed protocol has been designed to have an ability to accommodate integrated traffic in the network with effective scheduling schemes. A series of simulation experiments have been carried out to evaluate the performance of the proposed protocol and scheduling algorithms. The results reveal that the proposed protocol with the scheduling performs effectively to the integrated traffic composed of messages with or without time constraints and achieves fairness among different types of traffic. Author Affiliation: School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang, Singapore

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2005.09.004 Byline: M. Fikret Ercan (a), Ceyda OAuz (b) Keywords: Multiprocessor task scheduling; Metaheuristics; Parallel computing Abstract: This paper presents the evaluation of the solution quality of heuristic algorithms developed for scheduling multiprocessor tasks for a class of multiprocessor architectures designed to exploit temporal and spatial parallelism simultaneously. More specifically, we deal with multi-level or partitionable architectures where MIMD parallelism and multiprogramming support are the two main characteristics of the system. We investigate scheduling a number of pipelined multiprocessor tasks with arbitrary processing times and arbitrary processor requirements in this system. The scheduling problem consists of two interrelated sub-problems, which are finding a sequence of pipelined multiprocessor tasks on a processor and finding a proper mapping of tasks to the processors that are already being sequenced. For the solution of the second problem, various techniques are available. However, the problem remains of generating a feasible sequence for the pipelined operations. We employed three well-known local search heuristic algorithms that are known to be robust methods applicable to various optimization problems. These are Simulated Annealing, Tabu Search, and Genetic Algorithms. We then conduct computational experiments and evaluate the reduction achieved in completion time by each heuristic. We have also compared the results with well-known simple list-based heuristics. Author Affiliation: (a) School of Electrical and Electronic Engineering, Singapore Polytechnic, 500 Dover Road, Singapore 139651, Singapore (b) Department of Industrial Engineering, Koc University, Rumeli Feneri Yolu, Sariyer, Istanbul 34450, Turkey Article History: Received 4 February 2005; Revised 20 August 2005; Accepted 8 September 2005