Laid Kahloul

Designing reconfigurable manufacturing systems using reconfigurable object Petri nets

In reconfigurable manufacturing systems (RMSs), the structure of the system can be changed during its execution. This reconfiguration can be triggered by several motivations: a new requirement in the production process, avoiding some problems caused by machines breakdowns, etc. RMSs are characterised by their flexibility which guarantees productivity and efficiency. However, their design is more complicated and needs new techniques and paradigms. The use of high level Petri nets (PNs) offers the ability to design these systems and to analyse their properties. In this article, the authors apply reconfigurable object nets (RONs) for the modelling, simulation and analysis of RMSs. Indeed, a formal method is proposed, where the reconfiguration process is specified explicitly as a graph transformation, the simulation is realised using the RON-tool, and the analysis exploits the TINA-tool (timed nets analyser tool).

Using High Level Petri Nets in the Modelling, Simulation and Verification of Reconfigurable Manufacturing Systems

In Reconfigurable Manufacturing Systems (RMSs), the structure of the system can be changed during execution of the system. This reconfiguration can be motivated by a new requirement in the production process, or to avoid some problems caused by machines breakdowns. These systems offer a high flexibility leading to more productivity and efficiency. However, their design is more complicated implying new techniques and paradigms. The use of formal high level Petri Nets offers the ability to design these systems and to analyse or prove their properties. In this paper, we apply Reconfigurable Object Nets (RONs) for the modelling, simulation and analysis of reconfigurable manufacturing systems. We propose a formal approach, where the reconfiguration is specified as graph transformations, the simulation is realized using the RON-tool, and the analysis exploits some software tools such as TINA-tool and PIPE-tool.

A new "data size" based algorithm for itinerary planning among mobile agents in wireless sensor networks

The integration of mobile agent systems in the wireless sensor networks (WSN) has a positive impact on this type of networks. The itineraries followed by mobile agents have a influences significantly on the energy consumption. Finding an optimal sequence of visited source nodes (data sensors) is an NP-hard problem. Many researches have dealt with itinerary planning in WSNs through the use of a single agent (SIP: Single agent Itinerary Planning) or multiple mobile agents (MIP: Multiple agents Itinerary Planning). The itinerary planning, for multiple agents in WSN (MIP), must consider the following three issues: (i) the appropriate number of Mobile Agents, (ii) the suitable grouping of source-nodes, (iii) and finally, the optimal itinerary for each Mobile Agent to visit all its associated nodes. In the current MIP solutions, the geographical distance is the unique factor motivating to plan the itinerary of the agents. These solutions dont consider the data size provided by each node which is another factor affecting energy consumption too.n In this paper, we provide a new MIP solution which is based on the both basic factors (geographical distance and data size) affecting energy consumption. Using these two factors, this study provides a new way for determining the number of mobile agents and for grouping source-nodes. Once, the number of mobile agents and the node groups are defined, we identify the itinerary (a path passing through the set of source nodes that must be visited by the mobile agent). The itinerary is defined using the GRASP (Greedy randomized adaptive search procedure) heuristic algorithm. The simulation results prove that our proposal is more efficient than other existing approaches in terms of task duration and the amount of consumed energy.

Net rewriting system for GSPN a RMS case study

The use of Petri Nets in the design of Reconfigurable Manufacturing Systems is an attractive field. Petri Nets allow modelling in an abstract way RMSs and to make specification, refinement, verification and validation of these systems. Moreover, the use of Stochastic Petri Nets allows the designer to catch more indispensable aspects (time and stochastic events) of RMSs, thus the designer can make performance evaluation. In order to study the reconfigurability, explicitly, in Petri nets, several works proposed extension for PN called reconfigurable Petri nets. However, these extensions do not deal yet with stochastic Petri nets. The objective of this paper is to present an extension of Stochastic Petri nets to deal with reconfigurability.

Reconfigurable Stochastic Petri Nets for Reconfigurable Manufacturing Systems

The use of Petri Nets in the design of Reconfigurable Manufacturing Systems is an attractive field. Petri Nets allow modelling RMSs in an abstract way and to make specification, refinement, verification and validation of these systems. Moreover, the use of Stochastic Petri Nets allows the designer to catch more indispensable aspects (time and stochastic events) of RMSs, thus the designer can make performance evaluation. In order to study explicitly the reconfigurability, in Petri nets, several works proposed the extension of PN called reconfigurable Petri nets. However, these extensions do not deal yet with stochastic Petri nets. The objective of this paper is to present an extension of Stochastic Petri nets to deal with reconfigurability in manufacturing.

Two-Level Data Collection for an Energy-Efficient Solution in Wireless Sensor Networks: Multi-Agent System Approach

Density in sensor networks often causes data redundancy, which is often the origin of high energy consumption. Data collection techniques are proposed to avoid retransmission of the same data by several sensors. In this paper, the authors propose a new data collection strategy based on static agents and clustering nodes in wireless sensor network (WSN) for an efficient energy consumption called: Two-Level Data Collection Strategy (TLDC). It consists in two-level hierarchy of nodes grouping. The technique is based on an experience building to perform a reorganization of the groups. Cooperation between agents can be used to reduce the communication cost significantly, by managing the data collection smartly. In order to validate the proposed scheme, the authors use the timed automata (TA) model and UPPAAL engine to validate the proposed strategy; the results after and before reorganization are compared. They establish that the proposed approach reduces the cost of communication in the group and thus minimizes the consumed energy.

A Novel Approach for Mobile Maintenance Using Mobile Agents Technology and Mobile Devices

The long use of a system causes its degradation. Hence, the maintenance activity is required in order to keep and improve the efficiency in the system. With the rapid development in networking technology, a need appears to change the manufacturing strategies. These new technologies improve the maintenance process, and establish remote maintenance (tele-maintenance, e-maintenance and m-maintenance). These kinds of maintenance try to provide personnel maintenance with the right information at the suitable time, which makes information available, anywhere and anytime. Our proposition is the use of mobile agent technology to reduce the maintenance costs and solve the problem of the unavailability of an expert in all phases of condition-based maintenance (CBM) strategy. The mobile agent technology overcomes a lot of problems and there is not much work that has used this technology. We have also used the web services (WS) to insure interoperability between machines and to support interaction over the network. O...

A dynamic skyline technique for a context-aware selection of the best sensors in an IoT architecture

Abstract The integration of the Internet of Things (IoT) paradigm into web services and cloud computing allows us to handle thousands of sensors and their data. In this regard, sensing as a service model has recently emerged and the data generated by these sensors can be reused by different users and applications within IoT middleware solutions. With the huge number of sensors available in the IoT environment, the crucial challenge is how to efficiently search and select the best sensors depending on the users’ requirements. This paper aims to exploit the power of a dynamic skyline operator in the field of multi-criteria decision making, to reduce the search space for the purpose of improving the efficiency of context-awareness and selecting the best sensors following the users’ request. The architecture adopted in this proposition is composed by several gateways distributed in the network and connected with a server, where each gateway must respond to user requests locally. Hereafter, the server will aggregate the results of all gateways and give the final answer. The experimentation shows the efficiency of our method in comparison to existing ones.

FRABAC: a new hybrid access control model for the heterogeneous multi-domain systems

In this paper, a new hybrid, flexible, scalable and fine-grained model, fine-grained role-attribute access control (FRABAC) is proposed. FRABAC combines the benefits of the two most popular basic models: role-based access control (RBAC) and attribute-based access control (ABAC). The new proposed model overcomes the shortcomings of both models RBAC and ABAC known as combinatorial explosion in rules and roles when the security policy becomes complicated. Besides avoiding the combinatorial explosion, the new proposed model provides a role permission agreement (APA) to handle inter organisational access decision in collaborative cloud services cases. The proposed model is applied to define the security policies in realistic case studies and results are compared to previous existing models. On the other hand, the consistency and the correctness of the built policies are analysed through a formal modelling/analysis approach. This formal approach uses hierarchical coloured Petri nets (HCPNs) to model the policy and the CPN-tools to analyse the generated models.

A new hybrid access control model for multi-domain systems

Access control is an important issue in multi-domain information systems. A variety of access control models have been developed to address different aspects of security problems in such systems. Currently, the two most popular models are role-based access control (RBAC) and Attribute-based access control (ABAC). Providing a hybrid model which considers both the “role” concept and the “attributes” has become an important research topic. In this paper, we propose a new access control model based principally on roles, attributes, access modes and the type of resources. This model combines the advantages of the two models RBAC and ABAC and overcomes their limitations.