Mohamed Khalgui

The paper combines two approaches: "the classical formal approach based on Petri nets and their extensions" with the "evolutionary approach" represented by genetic algorithms, i.e. NSGA 2. The paper provides a new combined formalism that aims both to exploit the power of the genetic algorithm to find optimal solutions as well as to take advantage o...

This paper addresses the formal verification of reconfigurable discrete event systems (RDESs) using Isabelle/HOL proof assistant. A reconfigurable system transitions from one mode to another during its operation to adapt its behavior to the relevant environment. By including such a feature, RDESs become complex and are often costly in terms of comp...

Coordinated vehicle route guidance is recognized as an effective way to alleviate the Braess' paradox that new congestion is generated since numerous vehicles obey the same guidance from Google Maps. In conventional route games, decision‐makers are assumed to be completely rational (maximized utility is taken as an optimization objective). However,...

Recently, reconfigurable wireless sensor networks (RWSNs) have attracted a lot of attention in research and industrial communities. They became more complex and dynamic systems which led to the emergence of many challenges. The lack of energy, real-time constraints, and software and hardware failures are the most important challenges in RWSNs. Inde...

Generalized stochastic Petri nets (GSPNs) have been extended to several dynamic-structure formalisms providing suitable tools for the modeling and verification of reconfigurable discrete-event systems (R-DESs). However, analyzing the performance of large-complex R-DESs remains a big challenging issue. Indeed, dynamic-structure GSPNs still rely on o...

The definition of an electricity trading protocol among microgrids is not an easy task to perform due to the grid's increasing requirements. In fact, a trading process must provide security and especially privacy of the buyer and seller identities as well as prices. Also, guaranteeing a financial profit to trading parties is of great importnace. Mo...

Developing Smart Grids (SG) requires more advanced software engineering tools to keep-up with the growing requirements. Reconfiguration, context-awareness, and security features are becoming necessary for the smart and reliable behavior of future electricity grids. Several software solutions have been proposed to improve the development of such fea...

In the discrete event systems literature, the studies addressing opacity usually assume a passive intruder, who has full knowledge of the structure of a system but with only a partial observation ability. This work touches upon the opacity problem in discrete event systems modeled with labeled Petri nets , by assuming the existence of an active int...

In this paper, an asymmetrical congestion game is used to build a fairness concern‐based coordinated route guidance model for alleviating traffic congestion. Coordinated vehicle route guidance is commonly recognized as an effective way to alleviate the “route flapping” phenomenon, where a new congestion appears since numerous vehicles obey the same...

This poster is about a new energy efficient and fault tolerant methodology based on a multi-agent architecture in Reconfigurable Wireless Sensor Networks.

This paper deals with the modelling and verification of reconfigurable discrete event systems using model driven engineering Hadoop. Hadoop is therefore a platform for establishing a dialogue between several machines. Its objectives are to solve the main problems of Hard disk size and of computing powers limitations. Isabelle/HOL is an interactive/...

As today's reconfigurable distributed control systems become more and more complex, the modelling of its controlling applications becomes more difficult. The Unified Modelling Language (UML) is considered as a standard language for modelling software and systems. However, UML does not provide formal semantics that allow correctness verification. It...

Unmanned aerial systems (UAVs) are dramatically evolving and promoting several civil applications. However, they are still prone to many security issues that threaten public safety. Security becomes even more challenging when they are connected to the Internet as their data stream is exposed to attacks. Unmanned traffic management (UTM) represents...

Future distributed reconfigurable systems need to provide smarter services. Therefore the used software need to include advanced mechanisms such as the context-awareness, artificial intelligence, collaboration between distributed parts of the system, as well as the secure data exchange. Most of the existing context-aware frameworks are restricted t...

This article deals with reconfigurable uniprocessor systems powered by a renewable energy source under real-time and resource sharing constraints. A reconfigurable system is defined as a set of implementations, each of which is encoded by real-time periodic software tasks. Reconfiguration is a flexible runtime scenario that adapts the current syste...

Since microgrid systems are growing in complexity, the development of its control software becomes more and more difficult. This is why the use of high level abstraction modelling becomes a crucial need to cope with this increasing complexity. Defining commonly understandable software models is a challenging task due to many reasons such as the dif...

This article deals with improved formal verification of reconfigurable discrete-event systems (DESs) modeled by reconfigurable timed net condition event systems (R-TNCESs). An R-TNCES consists of a set of timed net condition event systems, each of which represents a particular behavior of a DES, and a reconfiguration scenario is a switching mode fr...

This paper deals with the formal verification of reconfigurable discrete event systems. We use the formalism called reconfigurable timed net condition/event systems (R-TNCESs) which is a Petri net pattern that deals with reconfiguration properties. Systems can experience malfunctioning due to hardware failures or software errors. Model-based diagno...

The architecture of smart distribution systems is becoming more and more complex after the appearance of networked microgrids. Maintaining the power balance between demand and supply in a cost effective way is turning into a very challenging task. Due to the intermittent nature of renewable energy and distributed architecture of microgrids (MGs), t...

Mapping complex hierarchical reconfigurable tasks on distributed architectures are classically an NP-hard problem. The current paper introduces a new software specification of these tasks with two-dimensional hierarchy levels DAGs. Each DAG is composed of multi-hierarchical subDAGs to specify graphs of complex software task graphs. We also propose...

Nowadays, multi-core architectures are being more and more used in the design of real-time systems. Those systems react usually to their environment that requires to amend their behaviors by applying reconfiguration scenarios. This paper deals with multi-core reconfigurable real-time systems that should be adapted to their environment under real-ti...

This paper deals with the real-time scheduling problem of multi-core systems powered by renewable energy harvested from environment. They handle two types of software tasks which are mapped to cores statically and not allowed to migrate. A task can be periodic which may depend on other tasks’ results, or aperiodic which is added to the system to co...

This paper deals with the scheduling of real-time periodic tasks executed on heterogeneous multicore platforms. Each processor is composed of a set of multi-speed cores with limited energy resources. A reconfigurable system is sensible to unpredictable reconfiguration events from related environment, such as the activation, removal or update of tas...

Nowadays, several systems like manufacturing, aerospace, medical, and telecommunication ones face new challenges such as fault-tolerance, response in time, flexibility, modularity, etc. To deal with these requirements, systems had to include new abilities. Consequently, systems become more complex, and their verification becomes expensive in terms...

This paper deals with improved verification of real-time systems that extend the classical formal verification with the rebuilding of reconfigurable timed net condition event systems (R-TNCESs). Indeed, previous computation tree logic (CTL) model repair approaches make the model checking eligible for generating a new correct model from a faulty one...

To enhance the recovery of the enormous number of failures of electric grids and guarantee the best power availability during technical team interventions, we have proposed a strategy that predicts the number of renewable sources needed for fault recovery by respecting total required loads and given budget by the ministry. In this paper, we improve...

This paper deals with formal verication of recon-gurable discrete event control systems (RDECSs) using recongurable timed net condition/event systems (R-TNCESs) formalism. A recongurable system switches from a mode to another during its working process to adapt its behavior to the related environment. By including such a feature, RDECSs become comp...

To overcome the problem of critical failures recovery and improve reliability, quality of service and recovery performance, it is essential to provide and apply a new oriented solution for smart grid reconfiguration. This solution allows for resolving the problem of the late intervention of technical teams and the insufficiency of energy for recove...

This paper deals with reconfigurable wireless sensor networks (RWSNs) to be composed of a set of sensor nodes, which monitor the physical and chemical conditions of the environment. RWSNs adapt dynamically their behaviors to their environment. The main challenge in RWSN is to keep the network alive as long as possible. We apply a set of solutions f...

This paper addresses the allocation of Energy Storage Systems (ESSs) in power grids by finding the optimal number of ESSs and their locations and sizes with the goal of improving reliability in contingency states. We propose a contingency-sensitivity-based heuristic to decide the optimal number of ESSs and the most effective locations for ESSs supp...

N owadays, reconfigurable real-time systems are found in diverse applications, such as avi-onics, automotive electronics, telecommunications and sensor networks. A reconfigurable system is defined as a set of implementations, each of which is encoded by real-time periodic software tasks. In these systems, the correct behavior depends not only on th...

Smart grids are critical cyber-physical power systems that are characterized by reliable and safe operation against physical faults and cyber attacks. Smart grid systems have to be developed for the protection from cyber-physical threats by taking the necessary countermeasures. To address this problem, this paper proposes a unified framework that c...

To guarantee a better power availability in complex power systems, this paper provides a new strategy that deals with smart grids rebuilding for fault recovery. We propose a heuristic that schedules technical team interventions and allows to carry favor clients with no recovery sources compared with those that are covered by renewable sources, and...

Demand side management (DSM) is one of the main functionalities of the smart grid as it allows the consumer to adjust its energy consumption for an efficient energy management. Most of the existing DSM techniques aim at minimizing the energy cost while not considering the comfort of consumers. Therefore, maintaining a trade-off between these two co...

Smart distribution systems are critical cyber-physical energy systems that consists of multiple networked microgrids (MGs) with a distributed architecture. The main problem behind these cyber-physical energy systems is how to manage energy sources to have an efficient and economic energy supply. This paper proposes a cooperative energy management s...

IEC 61499 provides a standardized approach for the development of distributed control systems. The standard introduces a component architecture, based on function blocks that are event-triggered components processing data and signals. However, it gives only limited support for the design of reconfigurable architectures. In particular, handling of s...

Nowadays, multi-core architectures are increasingly being adopted in the design of emerging complex real-time systems. Meanwhile, implementing those systems as threads generates a complex system code due to the large number of threads, which may lead to a reconfiguration time overhead as well as redundancy increases. In this paper, we present a nov...

The Micro Air Vehicle Link (MAVLink in short) is a communication protocol for unmanned systems (e.g., drones, robots). It specifies a comprehensive set of messages exchanged between unmanned systems and ground stations. This protocol is used in major autopilot systems, mainly ArduPilot and PX4, and provides powerful features not only for monitoring...

The Micro Air Vehicle Link (MAVLink in short) is a communication protocol for unmanned systems (e.g., drones, robots). It specifies a comprehensive set of messages exchanged between unmanned systems and ground stations. This protocol is used in major autopilot systems, mainly ArduPilot and PX4, and provides powerful features not only for monitoring...

This paper deals with improved rebuilding of models in formal verification of reconfigurable discrete-event systems (RDESs) modeled by reconfigurable timed net condition event systems (R-TNCESs). Automated computation tree logic (CTL) model update and repair are approaches that extend model-checking to generate a new correct model that represents t...

This paper deals with formal modeling and verification of reconfigurable real-time systems under reconfigura-bility and real-time constraints. To deal with the modeling, we enrich the formalism, named reconfigurable timed net condition event systems (R-TNCESs), with new reconfiguration forms such as the ability to update the earliest/latest firing...

The MAVLink is a lightweight communication protocol between Unmanned Aerial Vehicles (UAVs) and ground control stations (GCSs). It defines a set of bi-directional messages exchanged between a UAV (aka drone) and a ground station. The messages carry out information about the UAV's states and control commands sent from the ground station. However, th...

The paper deals with microgrids in an islanded location where only local generator sources are deployed. However, microgrids in isolated mode are susceptible to unplanned meteorological changes. The defy is to improve the autonomy of these microgrids; thus we start first by checking the required availability of power in the microgrid after unexpect...

In the last few years, Unmanned Aerial Vehicles (UAVs) are making a revolution as an emerging technology with many different applications in the military, civilian, and commercial fields. The advent of autonomous drones has initiated serious challenges, including how to maintain their safe operation during their missions. The safe operation of UAVs...

In the last few years, Unmanned Aerial Vehicles (UAVs) are making a revolution as an emerging technology with many different applications in the military, civilian, and commercial fields. The advent of autonomous drones has initiated serious challenges, including how to maintain their safe operation during their missions. The safe operation of UAVs...

The paper deals with the intelligence adaptation of distributed real-time embedded control systems when scenarios of reconfiguration happen in their hardware or software level. The reconfiguration process is a composition of controllers reconfiguration by adding/deleting or updating tasks and intelligence reconfiguration by adding/deleting and upda...

This paper deals with the medium between two reconfigurable sensor nodes characterized by radio interfaces that support multiple channels for exchanging real-time messages under energy constraints. These constraints are violated if the consumed energy in transmission is higher than the remaining quantity of energy. A reconfiguration, i.e., any addi...

This paper deals with testing a distributed reconfigurable hardware systems (DRHSs) by proposing a new extension of the IEEE Std. 1149.1 named reconfigurable joint test action group (RJTAG). The first step introduces an extension of the boundary scan architecture by changing the usual boundary scan register (BSR) into a reconfigurable BSR. The seco...

A microgrid is a small-scale smart network that contains distributed resources and loads and serves several technical, economic and environmental aims. In this kind of power system, the energy generated by the different sources is often collected in an adequate bus system (AC or DC busses), and transported to loads across a distribution system. In...

This paper presents an overview on different research activities that we did in the recent decade for developing reconfigurable discrete-event systems (RDESs) from initial high level specification according to user requirements until final low level deployment in target hardware components. A reconfiguration is any run-time scenario that adapts the...

The original version of the chapter “CRMPSoC: New Solution for Feasible Reconfigurable MPSoC”, starting on p.175 was revised. An affiliation has been added. The original chapter was corrected.

This paper proposes a deadlock prevention method to design a maximally permissive liveness-enforcing pure Petri net supervisor for a discrete event system, if such a supervisor exists; otherwise, it obtains the most permissive one in the sense that no other pure liveness-enforcing supervisors via linear monitors can be more permissive than it. This...

This study presents an improved parallel rebuilding of reconfigurable timed net condition-event systems (RTNCESs) modeling reconfigurable discrete-event systems (RDESs). Computation tree logic (CTL) model repair is one of the existing approaches that extends formal verification using model checking, by an automatized debugging phase and updating di...

This research paper deals with combining semi-formal and formal methods to develop distributed reconfigurable control systems (DRCSs). The reconfiguration consists in modifying the system behavior to adapt it to the changes in its related environment caused by user needs and operating constraints. A DRCS which consists of networked reconfigurable c...

Demand side management (DSM) is one of the main functionalities of the smart grid as it allows the consumer to adjust its energy consumption for an efficient energy management. Most of the existing DSM techniques aim at minimizing the energy cost while not considering the comfort of consumers. Therefore, maintaining a trade-off between these two co...

This paper deals with multi-channel reconfigurable WSN (RWSN) under time and energy constraints, that adapts its behavior at run-time to any evolution in the related environment according to well-defined conditions. A reconfiguration scenario is adding new tasks and consequently new messages on the medium, removing other ones or changing their char...

The deadlock control problem in automated manufacturing systems (AMSs) has received much attention in recent years due to the flexibility of an AMS. In the framework of Petri nets, resourcetransition circuits and siphons are often used to characterize and derive a deadlock control policy for an AMS. This paper mainly focuses on a class of Petri net...

A deluge of approaches has been proposed to implement and deploy a computationally effective and maximally permissive liveness-enforcing supervisor for sequential resource allocation systems (RASs). However, they are stalled by the computational complexity of a large state space that grows exponentially with respect to the size of an underlying RAS...

Low-cost Unmanned Aerial Vehicles (UAVs), also known as drones, are increasingly gaining interest for enabling novel commercial and civil Internet-of-Things (IoT) applications. However, there are still open challenges that restrain their real-world deployment. First, drones typically have limited wireless communication ranges with the ground statio...

This paper deals with the formal verification of reconfigurable discrete event control systems (RDECSs) using reconfigurable timed net condition/event systems (R-TNCESs) formalism. A reconfigurable system switches from a mode to another during its working process to adapt its behavior to the related environment. By including such a feature, RDECSs...

This paper deals with software validation of flexible discrete-event systems. A reconfiguration scenario is any run-time adaptation of the software execution according to user requirements. Nevertheless, since several behaviors can be redundant from an execution to another, using the object constraint language (OCL) is not useful to specify all con...

State space techniques are one of the main approaches deployed for the analysis of concurrent systems. However, state space construction is stalled by a common phenomenon called the state explosion problem which makes it a tough task or even impossible when the state space computation demands prohibitive cost (time and memory). We limit general res...

This paper deals with real-time scheduling of homogeneous multi-core platforms powered by a battery to be periodically recharged. A system is composed of reconfigurable real-time dependent and periodic tasks to be assigned to different cores interconnected by a network-on-chip (NoC). The system is subject to reconfigurations, which are automatic op...

Adaptive probabilistic systems have ability to modify their behaviors to cope with unpredictable significant changes at run-time such as component failures or resources depletion. Reconfiguration is often a major task for systems, i.e., it may violate the memory usage, the required energy and the concerned real-time constraints. It might also make...

The paper deals with the dynamic reconfiguration of networked devices linked by a controller area network (CAN). Each device runs dependent periodic and aperiodic software tasks and can be adapted to any evolution in its environment. A reconfiguration is a dynamic scenario that activates-deactivates the deployed devices, adds-removes software tasks...

This paper focuses on establishing a Petri net (PN) -based deadlock prevention policy for large-scale systems whose state spaces are prone to the explosion problem phenomenon. When using the reachability analysis technique, the main burden is that the number of states grows exponentially with respect to the PN structure and, thereby, synthesizing a...

Reconfiguration is often a major undertaking for systems because it can violate memory usage, the required energy and the concerned real-time constraints. The languages in which adaptive probabilistic systems are specified should be clear and intuitive, and thus accessible to generation, inspection and modification by humans. This paper introduces...

Wireless sensor networks (WSNs) can be seriously impacted by several changes in behavior. As a measure of optimality, a network should react in real-time. However, even if some reactions can make the system flexible, they can cause significant damages when they are not well-structured. Moreover, the scenarios of reconfigurations can affect several...

Recent critical embedded systems become more and more complex and usually react to their environment that requires to amend their behaviors by applying run-time reconfiguration scenarios. A system is defined in this paper as a set of networked devices where each of which has its own OS (Operating System), a processor to execute related periodic sof...

This paper deals with the test of a reconfigurable hardware system (RHS). The latter is a hardware device that allows to change the hardware resources at runtime in order to modify the system functions and therefore to dynamically adapt the system to its environment. The increasing functional complexity of embedded systems and the transition to the...

Power transmission lines of traditional power transmission systems (PTSs) may suffer from some faults that can lead to blackouts. This work proposes a methodology to construct hierarchical distributed control systems (DCSs) for the automatic fault detection and restoration of PTSs using colored Petri nets (CPNs). If faults occur in power transmissi...

This paper aims to enhance the reliability and quality of service (QoS) of power smart grids by searching and applying reconfiguration oriented solutions. A novel definition of recovery performance is provided in terms of automatic recoverability and unavailability rates. The proposed approach is based on a hierarchical and distributed multi-agent...

Hardware/software codesign involves various design problems including system specification, design space exploration, hardware/software co-verification, and system synthesis. An effective codesign process requires accurately predicting the performance, cost and power consequence of any design trade-off in algorithms and hardware configuration. This...

This paper deals with the reconfigurable real-time systems that should be adapted to their environment under real-time constraints. The reconfiguration allows moving from one implementation to another by adding/removing/modifying parameters of real-time software tasks which should meet related deadlines. Implementing those systems as threads genera...

This paper deals with reconfigurable discrete event/control systems (RDECSs) that dynamically change their structures due to external changes in environment or user requirements. Reconfigurable Timed Net Condition/Event Systems (R-TNCESs) are proposed as an extension of the Petri nets formalism for the optimal functional and temporal specification...

This paper presents new challenges for the real-time scheduling of distributed reconfigurable embedded systems powered by a renewable energy. Reconfigurable computing systems have to deal with unpredictable events from the environment such as activation of new tasks, hardware or software failures, by adapting the task allocation and scheduling in o...

This contribution aims to present a new framework called Reconfigurable Function Block, based on IEC61499 standard for industrial process measurement and control systems. It allows to optimize and simplify the design of reconfigurable systems by separating the reconfiguration model from the control model and presenting each reconfiguration scenario...

This poster was presented during the Doktorandentag 2017 of Saarland University.

Doktorandentag der Fakultät NT

To improve the power supply availability in an island microgrid, this paper proposes a new approach that integrates distributed energy sources economically, reliably and efficiently. In an island mode, a microgrid must ensure its self-sufficiency of energy production since it cannot make an energetic exchange with a main grid. However, in this mode...