Spelling suggestions: "subject:"data freshness"" "subject:"mata freshness""
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MELQART : un système d'exécution de mashups avec disponibilité de données / MELQART : a mashup execution system with data availabilityOthman Abdallah, Mohamad 26 February 2014 (has links)
Cette thèse présente MELQART, un système d'exécution de mashups avec disponibilité de données. Un mashup est une application web qui combine des données provenant de fournisseurs hétérogènes (web services). Ces données sont agrégées pour former un résultat homogène affiché dans des composants appelés mashlets. Les travaux dans le domaine des mashups, se sont principalement intéressés au fonctionnement des mashups, aux différents outils de construction et à leur utilisation et interaction avec les utilisateurs. Dans cette thèse, nous nous intéressons à la gestion de données dans les mashups et plus particulièrement à la disponibilité et la fraîcheur de ces données. L'amélioration de la disponibilité tient compte du caractère dynamique des données des mashups. Elle garantit (1) l'accès aux données même si le fournisseur est indisponible, (2) la fraicheur de ces données et (3) un partage de données entre les mashups afin d'augmenter la disponibilité de données. Pour cela nous avons défini un modèle de description de mashups permettant de spécifier les caractéristiques de disponibilité des données. Le principe d'exécution de mashups est défini selon ce modèle en proposant d'améliorer la disponibilité et la fraicheur des données du mashup par des fonctionnalités orthogonales à son processus d'exécution. Le système MELQART implante ce principe et permet de valider notre approche à travers l'exécution de plusieurs instances de mashups dans des conditions aléatoires de rupture de communication avec les fournisseurs de données. / This thesis presents MELQART: a mashup execution system that ensures data availability. A mashup is a Web application that application that combines data from heterogeneous provides (Web services). Data are aggregated for building a homogenous result visualized by components named mashlets. Previous works have mainly focused, on the definition of mashups and associated tools and on their use and interaction with users. In this thesis, we focus on mashups data management, and more specifically on fresh mashups data availability. Improving the data availability take into account the dynamic aspect of mashups data. It ensures (1) the access to the required data even if the provider is unavailable, (2) the freshness of these data and (3) the data sharing between mashups in order to avoid the multiple retrieval of the same data. For this purpose, we have defined a mashup description formal model, which allows the specification of data availability features. The mashups execution schema is defined according to this model with functionalities that improve availability and freshness of mashed-up data. These functionalities are orthogonal to the mashup execution process. The MELQART system implements our contribution and validates it by executing mashups instances with unpredictable situations of broken communications with data providers.
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Information Freshness and Delay Optimization in Unreliable Wireless SystemsYao, Guidan 02 September 2022 (has links)
No description available.
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OPTIMIZING DATA FRESHNESS IN INFORMATION UPDATE SYSTEMSBedewy, Ahmed M. 30 September 2021 (has links)
No description available.
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Network Utility Maximization Based on Information FreshnessCho-Hsin Tsai (12225227) 20 April 2022 (has links)
<p>It is predicted that there would be 41.6 billion IoT devices
by 2025, which has kindled new interests on the timing coordination between
sensors and controllers, i.e., how to use the waiting time to improve the
performance. Sun et al. showed that a <i>controller</i> can strictly improve
the data freshness, the so-called Age-of-Information (AoI), via careful
scheduling designs. The optimal waiting policy for the <i>sensor</i> side was
later characterized in the context of remote estimation. The first part of this
work develops the jointly optimal sensor/controller waiting policy. It
generalizes the above two important results in that not only do we consider
joint sensor/controller designs, but we also assume random delay in both the
forward and feedback directions. </p>
<p> </p>
<p>The second part of the work revisits and significantly
strengthens the seminal results of Sun et al on the following fronts: (i) When
designing the optimal offline schemes with full knowledge of the delay
distributions, a new <i>fixed-point-based</i> method is proposed with <i>quadratic
convergence rate</i>; (ii) When the distributional knowledge is unavailable,
two new low-complexity online algorithms are proposed, which provably attain
the optimal average AoI penalty; and (iii) the online schemes also admit a
modular architecture, which allows the designer to <i>upgrade</i> certain
components to handle additional practical challenges. Two such upgrades are
proposed: (iii.1) the AoI penalty function incurred at the destination is
unknown to the source node and must also be estimated on the fly, and (iii.2)
the unknown delay distribution is Markovian instead of i.i.d. </p>
<p> </p>
<p>With the exponential growth of interconnected IoT devices
and the increasing risk of excessive resource consumption in mind, the third
part of this work derives an optimal joint cost-and-AoI minimization solution
for multiple coexisting source-destination (S-D) pairs. The results admit a new <i>AoI-market-price</i>-based
interpretation and are applicable to the setting of (i) general heterogeneous
AoI penalty functions and Markov delay distributions for each S-D pair, and
(ii) a general network cost function of aggregate throughput of all S-D pairs. </p>
<p> </p>
<p>In each part of this work, extensive simulation is used to
demonstrate the superior performance of the proposed schemes. The discussion on
analytical as well as numerical results sheds some light on designing practical
network utility maximization protocols.</p>
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Analýza a optimalizace datové komunikace pro telemetrické systémy v energetice / Analysis and Optimization of Data Communication for Telemetric Systems in EnergyFujdiak, Radek January 2017 (has links)
Telemetry system, Optimisation, Sensoric networks, Smart Grid, Internet of Things, Sensors, Information security, Cryptography, Cryptography algorithms, Cryptosystem, Confidentiality, Integrity, Authentication, Data freshness, Non-Repudiation.
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