Non-numerical parallel algorithms for asynchronous parallel computer systems

The work in this thesis covers mainly the design and analysis of many important Non-Numerical Parallel Algorithms that run on MIMD type Parallel Computer Systems (PCSs), in particular the NEPTUNE and the SEQUENT BALANCE 8000 PCSs available at Loughborough University of Technology. [Continues.

A process - oriented verification and validation for real time embedded systems

Based on formal and robust concepts, the real-time embedded systems allow meeting the requirements for the quality of the systems. Considering the UML MARTE profile as the standard by excellence, it has been the most used in the modelling and analysis of systems. In addition, for the support of time constraints, the CCSL language (Clock Constraint Specification Language) has been proposed. However, the MARTE-CCSL profile allows only formal verification, which represents only the static validation. As a complement to the analysis, it is essential to consider the dynamic validation step as well. In this paper, we suggest a hybrid processoriented verification approach (HV&V) for MARTE-CCSL models. The HV&V approach is based on a transformation of MARTE-CCSL models to Timed CSP (Communicating Sequential Processes) models. Thus, the Timed CSP model and the generated counterexamples will be automatically used by the validation step. This last step helps to quickly generate a prototype that is functional and verifiable at low cost. The approach is tested on the elevator control system.Keywords:  Real Time Embedded Systems (RTES), Timed CSP (Communicating Sequential Processes), Clock Constraint Specification Language (CCSL), MARTE (Modeling and Analysis of Real Time Embedded Systems), V&V (Verification & Validation

A Twofold Self-Healing Approach for MANET Survivability Reinforcement

International audienceDistributed systems are by nature fault-prone systems. The situation becomes more complex in the presence of intrusions that continue to grow in both number and severity, especially in open environments like MANET. In this paper, we present a twofold self-healing approach to reinforce MANET survivability. First, a fault-tolerant IDS is designed by replication of individual agents within MASID to ensure continuous supervision of the network. However, since not all intrusions are predictable, there might have some serious effects on the network before being detected and completely removed. For that, even if the implications of intrusions could be minimized by the intrusion detection system MASID, still the need for the recovery of altered or deleted data is a vital step to ensure the correct functioning of the network. For that, a recovery-oriented approach for a self-healing MANET is also presented. It is based on the ability of MASID-R to assess the damage caused by the detected intrusions and aimed at enabling the supervised network to heal itself of those faults and damages. Simulations using ns-2 have been performed to study the feasibility and prove the optimality of the proposed approach

On the Design of a New Intrusion Detection System for Securing MANET: An Agent-Based Approach

MANETs for short, are increasingly gaining popularity. However, these networks are more vulnerable to attacks than wired networks. This is, mainly, due to their special nature and to the numerous constraints they present. Although many research works have been devoted to develop security mechanisms for MANETs, but still the optimal and efficient security solution not found. In this paper, we focus on intrusion detection in the mobile ad-hoc networks. Starting by an overview of the existing work in this field, and ending up with the proposal of a new distributed and cooperative architecture for intrusion detection. In order to overcome the weaknesses and flaws of the existing MANET intrusion detection systems (IDSs), this architecture integrates an agent-based detection process. So, the main principle of the proposed architecture is based on: (a) the distribution which is achieved through the implementation of a local intrusion detection system on each network node, and (b) the cooperation that is guaranteed by mobile and stationary agents’ collaboration. In that way we were able to have an IDS with so many interesting features such as: flexibility, distribution and cooperation, autonomy, lightweight, reactivity and fault tolerance which are extremely desired for any MANET intrusion detection system. The paper also discusses various constraints and limitations related to MANETs; and shows how effectively does our IDS manage to overcome them. 1

A Twofold Self-Healing Approach for MANET Survivability Reinforcement

International audienceDistributed systems are by nature fault-prone systems. The situation becomes more complex in the presence of intrusions that continue to grow in both number and severity, especially in open environments like MANET. In this paper, we present a twofold self-healing approach to reinforce MANET survivability. First, a fault-tolerant IDS is designed by replication of individual agents within MASID to ensure continuous supervision of the network. However, since not all intrusions are predictable, there might have some serious effects on the network before being detected and completely removed. For that, even if the implications of intrusions could be minimized by the intrusion detection system MASID, still the need for the recovery of altered or deleted data is a vital step to ensure the correct functioning of the network. For that, a recovery-oriented approach for a self-healing MANET is also presented. It is based on the ability of MASID-R to assess the damage caused by the detected intrusions and aimed at enabling the supervised network to heal itself of those faults and damages. Simulations using ns-2 have been performed to study the feasibility and prove the optimality of the proposed approach

Formal Verification of UML MARTE Specifications Based on a True Concurrency Real Time Model

The profile UML MARTE offers a general modeling framework for designing and analyzing real-time and embedded systems. Temporal aspects are critical criteria that should be taken into account during the design process. So, formal methods may be used to ensure the functional correctness of such systems. For this purpose, this paper defines an operational method for translating UML sequence diagrams annotated with MARTE stereotypes to time Petri nets with action duration specifications. The semantics of these specifications are defined in terms of duration action timed automata. This allows formal verification by means of several model checker tools like UPPAAL.390

Low Complexity Image Compression using Pruned 8-point DCT Approximation in Wireless Visual Sensor Networks

International audienceSince the transmission of the uncompressed image in the context of wireless visual sensor networks (WVSNs) consumes less energy than transmitting the compressed image, developing energy-aware compression algorithms are mandatory to extend the camera node's lifetime and thereby the whole network lifetime. The present paper studies a low-complexity image compression algorithm in the context of WVSNs. This algorithm consists of applying a pruning approach on a DCT approximation transform. The scheme is investigated in terms of computation cycles, processing time, energy consumption and image quality. Experimental works are conducted using the Atmel Atmega128 processor of Mica2 and MicaZ sensor boards. Simulation results show that the studied scheme can exhibit a competitive performance when compared against other algorithms. Furthermore, the scheme can achieve the best tradeoff between energy consumption and image quality

Hybrid intelligent framework for one-day ahead wind speed forecasting

International audienc