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Research results
Ph.D de

Group : Networking & Stochastic and Combinatorial Optimization

Déterminisme du transport dans les réseaux industriels critiques

Starts on 01/11/2009
Advisor : AL AGHA, Khaldoun

Funding : Convention industrielle de formation par la recherche
Affiliation : Université Paris-Sud
Laboratory : LRI & EDF Cachan

Defended on 26/09/2013, committee :
Rapporteur LABIOD Houda MdC HDR, Telecom ParisTech, France
PUJOLLE Guy Professeur, UPMC Paris 6, France
Examinateur VEQUE Veronique Professeur, L2S Université Paris-Sud, France
CHAOUCHI Hakima Professeur, Telecom SudPris, France
Directeur AL AGHA Khaldoun Professeur, LRI Université Paris-Sud, France
MARTIN Steven MdC-HDR, LRI Université Paris-Sud, France

Research activities :

Abstract :
In critical real-time systems, any faulty behavior may endanger lives. Hence, system verification and validation is essential before their deployment. In fact, safety authorities ask to ensure deterministic guarantees. In this thesis, we are interested in offering temporal guarantees; in particular we need to prove that the end-to-end response time of every flow present in the network is bounded. This subject has been addressed for many years and several approaches have been developed. After a brief comparison between the existing approaches, the Trajectory Approach makes a good candidate due to the tightness of its offered bound. This method uses results established by the scheduling theory to derive an upper bound. The reasons leading to a pessimistic upper bound are investigated. Moreover, since the method must be applied on large networks, it is important to be able to give results in an acceptable time frame. Hence, a study of the method’s scalability was carried out. Analysis shows that the complexity of the computation is due to both recursive and iterative processes. As the number of flows and switches increases, the total runtime required to compute the upper bound of every flow present in the network understudy grows rapidly. While based on the concept of the Trajectory Approach, we propose to compute an upper bound in a reduced time frame and without significant loss of precision. It is called "Scalable Trajectory Approach". After applying it to a network, the simulation results show that the total runtime was significantly reduced.

Ph.D. dissertations & Faculty habilitations
The original manuscript conceptualizes the recent rise of digital platforms along three main dimensions: their nature of coordination devices fueled by data, the ensuing transformations of labor, and the accompanying promises of societal innovation. The overall ambition is to unpack the coordination role of the platform and where it stands in the horizon of the classical firm – market duality. It is also to precisely understand how it uses data to do so, where it drives labor, and how it accommodates socially innovative projects. I extend this analysis to show continuity between today’s society dominated by platforms and the “organizational society”, claiming that platforms are organized structures that distribute resources, produce asymmetries of wealth and power, and push social innovation to the periphery of the system. I discuss the policy implications of these tendencies and propose avenues for follow-up research.