Abstract: This paper deals with the performance evaluation of a public transportation system in terms of waiting times at various connection points. The behaviour of a bus network is studied in the framework of Discrete Event Systems (DES). Two possible operating modes of buses can be observed at each connection stop: periodic and non-periodic mode. Two complementary tools, Petri nets and (max, +) algebra, are used to describe the network by a non-stationary linear state model. This one can be solved after solving the structural conflicts associated to the graphical representation. From the characteristic matrix of the mathematical model, we determine eigenvalues and eigenvectors that we use to evaluate the connection times of passengers. This work is finally illustrated with a numerical example.
Notes: Received 15 January 2007; accepted 27 August 2007. Available online 13 November 2007.
Abstract: Legal information certification and secured storage combined with documents electronic signature are of great interest when digital documents security and conservation are in concern. Therefore, these new and evolving technologies offer powerful abilities, such as identification, authentication and certification. The latter contribute to increase the global security of legal digital archives conservation and access. However, currently used cryptographic and hash coding concepts cannot intrinsically enclose cognitive information about both the signer and the signed content. Indeed, an evolution of these technologies may be necessary to achieve full text researches within hundreds or thousands of electronically signed documents. This article aims at describing a possible model along with associated processes to create and make use of these new electronic signatures called "meaningful electronic signatures" as opposed to traditional electronic signatures based on bit per bit computation.
Abstract: In this paper, we present a modeling approach of a pervasive e-learning application based on high-level Petri Nets. This graphical tool has been used as a powerful graphical modeling language during the three last decades. Their mathematical analysis techniques allow an analytical verification of many relevant properties of systems' behavior. Their powerful modeling allows a graphical description including various phenomena such as synchronization, parallelism and concurrency. The proposed model and the associated results, in this paper, point out a very clear trade-off between expressive power, analyzability and model consistency. The second contribution of the paper consists in the implementation of the application. This implementation is started with a conceptual analysis study. Then, Java technologies, XML language and Oracle data base are used to design the application.
Abstract: The rapid expansion of wireless technologies and their interactions with wired networks together with wide spread of GNSS infrastructures allow today the development of location-based services (LBS). Furthermore, the evolution of service oriented infrastructures enables information sharing between applications over the network. In this paper, a distributed interactive platform, called TransportML, for LBS interaction and cooperation is presented. It is an extended XML platform based on Services Oriented Architecture (SOA) principles to recognize, to monitor, and to collect service information and description over the network. A prototype is developed, in the context of intelligent transportation systems (ITS), to allow sharing information collected by each service and then acquiring more information about the driving context. This information helps drivers making appropriate decisions and, therefore, increases and improves road safety. The prototype is tested in urban and highway areas and results are reported to show the benefit of using this platform for sharing road information as well as services interaction.
Abstract: Dioid algebra associated with Petri Nets are appropriate tools for modeling, analyzing, and
evaluating the performance of Discrete Event Systems (DESs). These tools are restricted to model systems
characterized by choice phenomena and conflicts. In this paper a routing policy to arbitrate and resolve the
conflicts encountered while modeling DESs by dioid algebra, is proposed. This routing policy is illustrated by con-
sidering services interaction as a case study. Results are reported to show the eectiveness of the proposed policy.
Abstract: As Web services composition arouses a growing interest,
most research works address implementation and execution
issues. Therefore, many composition languages
(BPEL, XLANG, WSFL, WSCI, to name a few of them) have
been proposed in the past few years. However, a weakness
of these languages is that they are difficult to use in
early stages of development, such as specification. In this
paper, an extension to UML 2.0 called âUML-S: UML for
Servicesâ is introduced. UML-S allows for a Model Driven
Engineering (MDE) of Web services and their interactions.
Abstract: This paper presents a new approach based on (max, plus) algebra to model cooperative navigation in pervasive e- learning applications. This modeling approach is appropriate for modeling these systems that are governed, on the one hand, by events occurrence in a discrete state space, and on the other hand, by synchronization and parallelism phenomena. In addition, this approach enables to verify in a formal way the model consistency.
Abstract: Ubiquitous and pervasive networks and applications include a growing number of research themes. In most use cases, applications require location information to interpret their environment and behave accordingly. In this paper, location algorithms and positioning methods that can be used for wireless geolocation are presented.
Abstract: In this paper, solving of conflicts of a Petri net model with techniques of (max, plus) algebra is considered. We define a routing policy which enables to solve and arbitrate the associated conflicts with a Petri net. We show how the conflict solving semantic prevents the deadlock in a graphical model while introducing routing functions into modelling. To illustrate the proposed results, a public transportation network is worked out. The aim is to analyze and evaluate the performance of a bus network which is represented by a Petri net with conflicts and a state model in (max, plus) algebra.
