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Sadoudi S.,Polytechnic School of Algiers | Tanougast C.,CNRS System Conception, Modelisation, and Optimsation Laboratory | Azzaz M.S.,Polytechnic School of Algiers
Journal of Engineering Science and Technology Review | Year: 2015

A new non-coherent chaotic modulation technique based on adaptive decision threshold is proposed for the Ultra- WideBand (UWB) Direct Chaotic Communication (DCC) technology. The principal advantages of the proposed technique are: (1) Removing the threshold problem of the classical Chaotic On-Off Keying modulation technique which uses a nonzero decision threshold; (2) Providing a high throughput comparing to the others techniques since it do not uses any delay at the modulation; (3) Reducing the transmitted power, thanks to a transmitted bit energy devised by two. The obtained simulation results show high Bit Error Rate performances of the proposed technique applied in an UWB DCC system. In addition, the new chaotic modulation is more suitable in all DCC-based communications schemes. © 2015 Kavala Institute of Technology. Source

Kacem I.,CNRS System Conception, Modelisation, and Optimsation Laboratory
2013 2nd International Conference on Systems and Computer Science, ICSCS 2013 | Year: 2013

In this paper, we consider some practical scheduling problems under unavailability constraints (break-down periods, maintenance durations and/or setup times). Such problems can be met in different industrial environments and be associated to numerous real-life applications. The studied criteria are related to the maximum lateness minimization. The paper is organized in two main parts. The first part focuses on some special cases (makespan minimization when tails are equal and maximum lateness minimization when release dates are equal (see Section 2). The second part is devoted to the maximum lateness minimization (see Section 3). In each part, we present the main contributions and explain their principles (complexity results, heuristic algorithms and their worst-case performance, existing approximation schemes, exact methods, dynamic programming,...), Finally, Section 4 concludes the paper. © 2013 IEEE. Source

Kacem I.,CNRS System Conception, Modelisation, and Optimsation Laboratory | Kellerer H.,University of Graz | Seifaddini M.,CNRS System Conception, Modelisation, and Optimsation Laboratory
Journal of Combinatorial Optimization | Year: 2015

In this paper we deal with the single machine scheduling problem with one non-availability interval to minimize the maximum lateness where jobs have positive tails. Two cases are considered. In the first one, the non-availability interval is due to the machine maintenance. In the second case, the non-availability interval is related to the operator who is organizing the execution of jobs on the machine. The contribution of this paper consists in an improved fully polynomial time approximation scheme (FPTAS) for the maintenance non-availability interval case and the elaboration of the first FPTAS for the operator non-availability interval case. The two FPTASs are strongly polynomial. © 2015 Springer Science+Business Media New York Source

Habbas Z.,CNRS System Conception, Modelisation, and Optimsation Laboratory | Amroun K.,University of Abderrahmane Mira de Bejaia | Singer D.,CNRS System Conception, Modelisation, and Optimsation Laboratory
RAIRO - Operations Research | Year: 2016

Many real-world problems can be modelled as Constraint Satisfaction Problems (CSPs). Although CSP is NP-complete, it has been proved that non binary CSP instances may be efficiently solved if they are representable as Generalized Hypertree Decomposition (GHD) with small width. Algorithms for solving CSPs based on a GHD consider an extensional representation of constraints together with join and semi-join operations giving rise to new large constraint tables (or relations) needed to be temporarily saved. Extensional representation of constraints is quite natural and adapted to the specification of real problems but unfortunately limits significantly the practical performance of these algorithms. The present work tackles this problem using a compact representation of constraint tables. Consequently, to make algorithms compatible with this compact representation, new "compressed join" and "compressed semi-join" operations have to be defined. This last step constitutes our main contribution which, as far as we know, has never been presented. The correctness of this approach is proved and validated on multiple benchmarks. Experimental results show that using compressed relations and compressed operations improves significantly the practical performance of the basic algorithm proposed by Gottlob et al. for solving non binary CSPs with a Generalized Hypertree Decomposition. © 2016 EDP Sciences, ROADEF, SMAI. Source

Sadoudi S.,Polytechnic School of Algiers | Tanougast C.,CNRS System Conception, Modelisation, and Optimsation Laboratory | Azzaz M.S.,Polytechnic School of Algiers | Dandache A.,CNRS System Conception, Modelisation, and Optimsation Laboratory
Eurasip Journal on Image and Video Processing | Year: 2013

In this paper, we propose and demonstrate experimentally a new wireless digital encryption hyperchaotic communication system based on radio frequency (RF) communication protocols for secure real-time data or image transmission. A reconfigurable hardware architecture is developed to ensure the interconnection between two field programmable gate array development platforms through XBee RF modules. To ensure the synchronization and encryption of data between the transmitter and the receiver, a feedback masking hyperchaotic synchronization technique based on a dynamic feedback modulation has been implemented to digitally synchronize the encrypter hyperchaotic systems. The obtained experimental results show the relevance of the idea of combining XBee (Zigbee or Wireless Fidelity) protocol, known for its high noise immunity, to secure hyperchaotic communications. In fact, we have recovered the information data or image correctly after real-time encrypted data or image transmission tests at a maximum distance (indoor range) of more than 30 m and with maximum digital modulation rate of 625,000 baud allowing a wireless encrypted video transmission rate of 25 images per second with a spatial resolution of 128 × 128 pixels. The obtained performance of the communication system is suitable for secure data or image transmissions in wireless sensor networks. © 2013 Sadoudi et al. Source

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