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Research results
Ph.D de

Ph.D
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
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DESIGNING INTERACTIVE TOOLS FOR CREATORS AND CREATIVE WORK
Creative work has been at the core of research in Human-Computer Interaction (HCI). I describe the results of a series of studies that look at how creators work, where creators include artists with years of professional practice, as well as learners, or novices and casual makers. My research focuses on three creation activities: drawing, physical modeling, and music composition. For these activities, I examine how artists switch between representations and how these representations evolve throughout their creative process, from early sketches to fine-grained forms or structured vocabularies. I present interactive systems that enrich their workflow (i) by extending their computer tools with physical user interfaces, or (ii) by making physical materials interactive. I also argue that sketch-based representations can allow for user interfaces that are more personal and less rigid. My presentation will reflect on lessons and limitations of this work and discuss challenges for future design-support tools.