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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Reconnaissance de comportements complexes par traitement en ligne de flux d’événements / Online event flow processing for complex behaviour recognition

Piel, Ariane 27 October 2014 (has links)
L’analyse de flux d’évènements pour reconnaître des comportements complexes prédéfinis (Complex Event Processing – CEP) permet d’interpréter et de réagir à des quantités importantes de données ne pouvant être appréhendées telles quelles. Dans cette thèse, nous fournissons le cadre théorique général d’un CEP en adoptant une approche purement formelle qui assure une possibilité de vérification et d’analyse du processus de reconnaissance. Nous définissons un langage, le langage des chroniques, permettant de décrire les comportements complexes à reconnaître. Nous formalisons la notion de reconnaissance de chronique à l’aide d’une sémantique ensembliste fondée sur une représentation arborescente des reconnaissances. Dans une visée applicative, nous développons ensuite deux modèles du processus de reconnaissance. Le premier est réalisé avec le formalisme des réseaux de Petri colorés et permet de valider les principes de reconnaissance en faisant notamment ressortir les problèmes de concurrence et de modularité. Le second implémente directement le formalisme mathématique sous la forme d’une bibliothèque C++ appelée Chronicle Recognition Library (CRL) et disponible en open source. Nous tirons parti de cette implémentation pour traiter deux cas d’applications liés à l’insertion des drones dans l’espace aérien. La première vise à surveiller la cohérence d’un système de drones insérés dans le trafic aérien, en cas de pannes de liens de communication. Notre application permet d’une part de vérifier la cohérence des procédures actuellement mises en place en cas de pannes ; et d’autre part de compléter ces procédures par des alarmes dans les situations inévitables causées par des erreurs humaines. La seconde application surveille le bon respect des procédures de sécurité d’un drone partant en mission et traversant diverses zones, contrôlées ou non, de l’espace aérien. / Recognising complex predefined behaviours by the analysis of event flows (Complex Event Processing - CEP) alows to interpret and react to large quantities of data wich one would not be able to apprehend alone. In this Ph.D. thesis, we provide a general theoretical framework for CEP through a purely formal approach ensuring the possibility to check and analyse the recognition process. We define a language, the chronicle language, allowing the description of the complex behaviours to be recognised. We formalise the notion of chronicle recognition through a set semantics based on an arborescent representation of recognitions. In order to use this framework, we then develop two models of the recognition process. The first relies on coloured Petri nets and allows the validation of recognition principles including concurrency and modularity issues. The second model directly implements the mathematical formalism in a C++ library, chronicle recognition library (CRL), wich is avaible in open source. We use this implementation to fulfil two applications linked to the insertion of unmanned aircraft system inside air traffic in case of communication link breakdowns. This application allows, on the other hand, to check the consistency of the procedures currently followed in case of failures ; and, on the other hand, to complete these procedures with alarms in case of unavoidable situations caused by human errors. The second application oversees that the security procedures of an unmanned aircraft flying through controlled or uncontrolled airspace are correctly followed.
2

Processamento e caracterizações de ligas Al-Ti-V-Zr-Nb e Al-Ti-V-Cr-Nb (ligas com elementos multiprincipais) para aplicação aeroespacial / Processing and characterization of Al-Ti-V-Zr-Nb and Al-Ti-V-Cr-Nb alloys (multi-principal elements alloys) for aerospace application

Moraes Junior, José Mauro 21 June 2018 (has links)
Foram estudadas MPEAs com diferentes composições químicas, das famílias Al-Ti-V-Zr-Nb e Al-Ti-V-Cr-Nb, visando desenvolver uma liga com propriedades interessantes para aplicação aeroespacial. As ligas foram produzidas em um forno a arco laboratorial, sob atmosfera de argônio. As primeiras ligas caracterizadas foram da composição equimolar de ambas famílias, mas não apresentaram microestrutura com solução sólida monofásica depois do tratamento térmico de homogeneização (1200°C/24h). Após ajustes na composição química duas ligas foram consideradas promissoras na caracterização microestrutural, após homogeneização, BZr7 e BCr8. Para avaliar a estabilidade microestrutural ambas foram expostas a alta temperatura por longo período de tempo (700ºC/168h), e ambas apresentaram pequena fração de segunda fase após esta exposição térmica. A dureza da BZr7 e da BCr8, após exposição térmica, foi de 3,46 e 4,91 GPa, respectivamente. Ambas foram laminadas a 1000 °C, encapsuladas em tubo de aço inoxidável austenítico para evitar oxidação, mas apenas a BZr7 apresentou conformabilidade, sendo a BCr8 não utilizada nos testes subsequentes. A BZr7 exposta termicamente apresentou, na temperatura ambiente, tensão limite de escoamento, em compressão, de 1250 MPa. A tensão limite de escoamento se manteve alta em temperaturas elevadas, sendo 1080, 720 e 690 MPa nas temperaturas de 600, 700 e 800 °C, respectivamente. A massa específica é de 6,34 g/cm3, que originou tensões de escoamento específicas de 197,2 kPa.m3/kg na temperatura ambiente, e 170,3, 113,6 e 108,8 kPa.m3/kg nas temperaturas de 600, 700 e 800 °C, respectivamente, resultados bem melhores que das três ligas convencionais usadas como referência neste trabalho, Ti6Al4V, Tiβ21s e Inconel 625. Além de boa resistência em compressão a liga apresentou boa ductilidade na temperatura ambiente (ε = 38%). Apenas a MPEA refratária AlNbTiVZr0,5, publicada por Stepanov et al. (2015d) e Yurchenko et al. (2017), apresentou combinação simultânea de alta resistência e boa ductilidade acima da liga BZr7 na temperatura ambiente. Apesar dos bons resultados de propriedades mecânicas, a liga apresentou baixa resistência à oxidação, tornando necessário revestimento para aplicações a elevadas temperaturas. / MPEAs with different chemical compositions, based in Al-Ti-V-Zr-Nb and Al-Ti-V-Cr-Nb families, were explored, aiming to develop an alloy with interesting properties for aerospace application. The alloys were produced in a laboratory arc furnace, with argon atmosphere. The equimolar composition of both families were the first characterized alloys, but did not exhibit single-phase solid solution microstructure after homogenization heat treatment (1200 °C/24h). After adjustments in the chemical composition two alloys were considered promising in the microstructural characterization after homogenization, BZr7 and BCr8. To evaluate the microstructural stability both alloys were exposed to high temperature for long period of time (700ºC/168h), and both presented small fraction of second phase after this exposure heat treatment. The microhardness of BZr7 and BCr8 alloys, after thermal exposure, was 3.46 and 4.91 GPa, respectively. Both were rolled at 1000 ° C, after encapsulation in austenitic stainless steel tube to avoid oxidation, but only BZr7 showed formability, than BCr8 was not considered for subsequent tests. The BZr7 alloy, after thermal exposure, exhibited 1250 MPa of yield stress at ambient temperature. The yield stress remained high at elevated temperatures, being 1080, 720 and 690 MPa at temperatures of 600, 700 and 800 ° C, respectively. BZr7 density is 6.34 g/cm3, resulting in a specific yield stress of 197.2 kPa.m3/kg, at room temperature, and 170.3, 113.6 and 108.8 kPa.m3/kg at temperatures 600, 700 and 800 °C, respectively, better results than the three conventional alloys tested in this work, Ti6Al4V, Tiβ21s and Inconel 625. In addition to good compressive yield stress, the alloy showed good ductility at room temperature (ε = 38%). Only the refractory MPEA AlNbTiVZr0.5, published by Stepanov et al. (2015d) and Yurchenko et al. (2017), showed a simultaneous combination of high yield stress and good ductility, above the BZr7 alloy, at room temperature. Despite the good results of mechanical properties, the BZr7 alloy showed low oxidation resistance, so coating is required for high temperature applications.

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