Cherif Tolba

Bio: Cherif Tolba is an academic researcher from University of Annaba. The author has contributed to research in topics: Routing protocol & Ad hoc On-Demand Distance Vector Routing. The author has an hindex of 5, co-authored 15 publications receiving 193 citations. Previous affiliations of Cherif Tolba include Universite de technologie de Belfort-Montbeliard.

Performances evaluation of the traffic control in a single crossroad by Petri nets

Abstract: Minimizing the queue length and vehicle delay time at crossroads is a major problem in the regulation of the traffic urban networks This paper deals with two formal approaches based on Petri nets for a single crossroad On one hand, these approaches make it possible to study the traffic behavior at crossroad in a microscopic point of view and in a macroscopic one On other hand, the developed models provide a tool for the performance analysis of the different traffic signal's control For this purpose, we show the performance indices of the vehicle interval control, which are obtained from simulation examples

Continuous Petri nets models for the analysis of traffic urban networks

Abstract: The traffic flow theory is concerned with finding a relation among the variables of traffic flow. We propose a new approach which consists of representing these variables by those of continuous Petri nets with variable speed (VCPN). A model of VCPN is suggested for the analysis and control design in urban and interurban networks. The proposed model provides representation for both motorway corridors and complex road junctions.

STPA and Bowtie risk analysis study for centralized and hierarchical control architectures comparison

Abstract: The industrial zones are increasingly invaded by groups of mobile robots that are the most capable to perform complex tasks by collaborating and cooperating together. The operation of a mobile robot within a dynamic and high-risk environment with strong interaction between robot-robot and human-robot is of a certain complexity of control and safety. Such type of systems requires a safety and hazard investigation to verify if it is able to operate under certain operating conditions, while still ensuring the control and collaboration between mobile robots and human. This paper presents an approach that combines aspects of System-Theoretic Process Analysis (STPA) and Bowtie for safety assessment purposes. The approach we propose is used for a case related to multi-robot systems considering the coordinating, cooperating and collaborating aspects. At first, a risk identification study is done using STPA to extract a set of risk scenarios related to different types of hierarchical coordination architectures in addition to their factors. Afterward, an evaluation of the obtained scenarios is performed by the Bowtie method. The aim of our study is to better compare different control approaches of a multi-agent system. The combination offers detailed hazard identification. It further provides a classification of risks which helps to improve STPA outcomes thus facilitate decision-making over the suitable approach.

A mixed approach load balancing and efficient energy for multi-path routing in mobile ad hoc networks

Abstract: Load balancing and energy efficient are recognized as a crucial issue in ad hoc networks. Several routing protocols have been proposed in order either to distribute equitably the workload among the nodes of network or to consume in efficient way the residual energy of nodes. In this paper, a novel approach is proposed to enhance the AODV routing protocol by considering the node capacity for relaying the data packets to the destination. The node capacity considers both the workload and remaining energy of node. Using these criteria, a modified AODV protocol is proposed AODV-LB which improves the packets delivery ratio and prolongs the network lifetime. Simulation shows that AODV-LB surpass the AODV and the protocol Energy Efficient Ad-hoc on Demand Vector (E2AODV) by reducing the consumed energy and the packets loss ratio in the network.

Evaluating effects of traffic and vehicle characteristics on vehicular emissions near traffic intersections

Abstract: Urban air quality is generally poor at traffic intersections due to variations in vehicles’ speeds as they approach and leave This paper examines the effect of traffic, vehicle and road characteristics on vehicular emissions with a view to understand a link between emissions and the most likely influencing and measurable characteristics It demonstrates the relationships of traffic, vehicle and intersection characteristics with vehicular exhaust emissions and reviews the traffic flow and emission models Most studies have found that vehicular exhaust emissions near traffic intersections are largely dependent on fleet speed, deceleration speed, queuing time in idle mode with a red signal time, acceleration speed, queue length, traffic-flow rate and ambient conditions The vehicular composition also affects emissions These parameters can be quantified and incorporated into the emission models There is no validated methodology to quantify some non-measurable parameters such as driving behaviour, pedestrian activity, and road conditions

Urban traffic control structure based on hybrid Petri nets

Abstract: An urban network of signalized intersections can be suitably modeled as a hybrid system, in which the vehicle flow behavior is described by means of a time-driven model and the traffic light dynamics are represented by a discrete event model. In this paper, a model of such a network via hybrid Petri nets is used to state and solve the problem of coordinating several traffic lights with the aim of improving the performance of some classes of special vehicles, i.e., public and emergency vehicles. The proposed model has been validated using real traffic data relevant to the city of Torino, Italy. Some relevant experimental results are reported and discussed.

Optimal Cycle Program of Traffic Lights With Particle Swarm Optimization

Abstract: Optimal staging of traffic lights, and in particular optimal light cycle programs, is a crucial task in present day cities with potential benefits in terms of energy consumption, traffic flow management, pedestrian safety, and environmental issues. Nevertheless, very few publications in the current literature tackle this problem by means of automatic intelligent systems, and, when they do, they focus on limited areas with elementary traffic light schedules. In this paper, we propose an optimization approach in which a particle swarm optimizer (PSO) is able to find successful traffic light cycle programs. The solutions obtained are simulated with simulator of urban mobility, a well-known microscopic traffic simulator. For this study, we have tested two large and heterogeneous metropolitan areas with hundreds of traffic lights located in the cities of Bahia Blanca in Argentina (American style) and Malaga in Spain (European style). Our algorithm is shown to obtain efficient traffic light cycle programs for both kinds of cities. In comparison with expertly predefined cycle programs (close to real ones), our PSO achieved quantitative improvements for the two main objectives: 1) the number of vehicles that reach their destination and 2) the overall journey time.

Coverage and Connectivity in WSNs: A Survey, Research Issues and Challenges

Abstract: Wireless Sensor Networks (WSNs) consist of several battery powered sensor nodes. The sensing coverage of the Field of Interest (FoI) is an important function of the sensor nodes in connected WSNs. A FoI is said to be covered if each point in the FoI is monitored by at least one sensor node. Due to small size, battery power supply, simple architecture, and light weight Operating System of the sensor nodes, maintaining the desired coverage of the FoI consists various issues and challenges in a connected WSN. This paper surveys the existing work done to address various issues and challenges for solving the coverage and connectivity problems in WSNs. Our discussion emphasis on sensing models, classification of coverage, research issues in WSNs and practical challenges in deployment of WSNs. We review a brief but complete overview of the various solutions of coverage problems in connected WSNs and describing insights into issues and challenges for research in this area.