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A buffer-aware worst-case timing analysis of wormhole NoC is proposed in this paper to integrate the impact of buffer size on the different dependencies relationship between flows, i.e. direct and indirect blocking flows, and consequently the timing performance. First, more accurate definitions of direct and indirect blocking flows sets have been introduced to take into account the buffer size impact. Then, the modeling and worst-case timing analysis of wormhole NoC have been detailed, based on Network Calculus formalism and the newly defined blocking flows sets. This introduced approach has been illustrated in the case of a realistic NoC case study to show the trade off between latency and buffer size. The comparative analysis of our proposed Buffer-aware timing analysis with conventional approaches is conducted and noticeable enhancements in terms of maximum latency have been proved., Comment: ISAE Technical report done during the master Thesis of Hamdi Ayed at ISAE at 2010

The aim of my thesis is to provide a resources-efficient gateway to connect Input/Output (I/O) CAN buses to a backbone network based on AFDX technology, in modern avionics communication architectures. Currently, the Remote Data Concentrator (RDC) is the main standard for gateways in avionics; and the existing implementations do not integrate any resource management mechanism. To handle these limitations, we design an enhanced CAN-AFDX RDC integrating new functions: (i) Frame Packing (FP) allowing to reduce communication overheads with reference to the currently used "1 to 1" frame conversion strategy; (ii) Hierarchical Traffic Shaping (HTS) to reduce contention on the CAN bus. Furthermore, our proposed RDC allows the connection of multiple I/O CAN buses to AFDX while guaranteeing isolation between different criticality levels, using a software partitioning mechanism. To analyze the performance guarantees offered by our proposed RDC, we considered two metrics: the end-to-end latency and the induced AFDX bandwidth consumption. Furthermore, an optimization process was proposed to achieve an optimal configuration of our proposed RDC, i.e., minimizing the bandwidth utilization while meeting the real-time constraints of communication. Finally, the capacity of our proposed RDC to meet the emerging avionics requirements has been validated through a realistic avionics case study.

The gateway impact on the end to end system performances is a major challenge in the design process of heterogeneous embedded systems. In this paper, this problem is tackled for a specific avionics network AFDX with CAN to identify the main interconnection issues. The results herein show the possible enhancements of the system performances thanks to an optimized gateway based on a frames pooling strategy, compared to a basic gateway.

A buffer-aware worst-case timing analysis of wormhole NoC is proposed in this paper to integrate the impact of buffer size on the different dependencies relationship between flows, i.e. direct and indirect blocking flows, and consequently the timing performance. First, more accurate definitions of direct and indirect blocking flows sets have been introduced to take into account the buffer size impact. Then, the modeling and worst-case timing analysis of wormhole NoC have been detailed, based on Network Calculus formalism and the newly defined blocking flows sets. This introduced approach has been illustrated in the case of a realistic NoC case study to show the trade off between latency and buffer size. The comparative analysis of our proposed Buffer-aware timing analysis with conventional approaches is conducted and noticeable enhancements in terms of maximum latency have been proved.

Ce travail vise l'amélioration des modèles eulériens à deux fluides pour l'hydrodynamique et le transfert de masse en écoulement turbulent à bulles. Nous étudions des zones de mélange oxygène-eau pour des taux de vide 2/infini/11%. Un gradient de taux de vide imposé en entrée génère des mouvements à grande échelle. La vitesse relative des bulles induit de profondes modifications de la turbulence aux petites échelles. On étudie donc des écoulements fortement contrôlés par la gravité. Nous avons fait des mesures locales caractérisant l'hydrodynamique et le champ d'oxygène dissous. Un travail de simulation numérique a consisté à améliorer les modèles d'échange interfacial de masse, de quantité de mouvement, et à prendre en compte la modulation de la turbulence qui modifie le transport turbulent. Les résultats obtenus avec le code Melodif montrent, qu'à condition de modéliser la modification des échelles par les interactions interfaciales, un bon accord avec les expériences est obtenu.