CASTRO-JUL Fátima, DÍAZ-REDONDO Rebeca P. , FERNÁNDEZ VILAS Ana, CHABRIDON Sophie, CONAN Denis Fog architectures and sensor location certification in distributed event-based systems. Sensors, january 2019, vol. 19, n° 1, pp. 104-1-104-26 URL: https://www.mdpi.com/1424-8220/19/1/104/pdf abstract
Since smart cities aim at becoming self-monitoring and self-response systems, their deployment relies on close resource monitoring through large-scale urban sensing. The subsequent gathering of massive amounts of data makes essential the development of event-filtering mechanisms that enable the selection of what is relevant and trustworthy. Due to the rise of mobile event producers, location information has become a valuable filtering criterion, as it not only offers extra information on the described event, but also enhances trust in the producer. Implementing mechanisms that validate the quality of location information becomes then imperative. The lack of such strategies in cloud architectures compels the adoption of new communication schemes for Internet of Things (IoT)-based urban services. To serve the demand for location verification in urban event-based systems (DEBS), we have designed three different fog architectures that combine proximity and cloud communication. We have used network simulations with realistic urban traces to prove that the three of them can correctly identify between 73% and 100% of false location claims
LIAO Jianwei, TRAHAY François, CAI Zhigang, XIONG Hailing, CHEN Shanxiong, ISHIKAWA Yutaka Fine granularity and adaptive cache update mechanism for client caching. IEEE systems journal, 2019, pp. 1-12 (document in press - published online 05 Sep 2018) abstract
Distributed file systems have been commonly used as the back end to provide high-performance I/O services for hosting complicated data processing, such as database workloads. By buffering the frequently used data in the local file cache, which is called the client caching mechanism, can reduce the I/O latency and improve the performance of file access. However, the overhead and complexity for ensuring data consistency may offset the performance benefits caused by data caching. This paper proposes an adaptive, per-block cache update mechanism, which can ensure data consistency of block data in a distributed file system, with low synchronization overhead. Specifically, based on the recent history of read/write requests, the proposed scheme can adaptively select the best-suited consistency update policy for each data block at run time. The experiments on database applications show that our newly proposed mechanism can greatly reduce the overhead resulted by maintaining cache consistency, especially for the workloads having fluctuating read/write ratios. As a consequence, the system performance can be also enhanced
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OUDART David, CANTENOT Jérôme, BOULANGER Frédéric, CHABRIDON Sophie An approach to design smart grids and their IT system by cosimulation. MODELSWARD 2019: 7th International Conference on Model-Driven Engineering and Software Development, Science and Technology Publications, Lda Av. D. Manuel I, 27A – 2º Dir 2900-595 Setúbal, Portugal : SCITEPRESS, 20-22 february 2019, Prague, Czech Republic, 2019 (document in press) abstract
Smart grids are the oncoming generation of power grids, which rely on information and communication technologies to tackle decentralized and intermittent energy sources such as wind farms and photovoltaic plants. They integrate electronics, software information processing and telecommunications technical domains. Therefore the design of smart grids is complex because of the various technical domains and modeling tools at stake. In this article, we present an approach to their design, which relies on model driven engineering, executable models and FMI based cosimulation. This approach is illustrated on the use case of an insular power grid and allows to study the impact of power production decisions
