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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.
61

Engineering Ecosystems of Systems: UML Profile, Credential Design, and Risk-balanced Cellular Access Control

Bissessar, David 14 December 2021 (has links)
This thesis proposes an Ecosystem perspective for the engineering of SoS and CPS and illustrates the impact of this perspective in three areas of contribution category First, from a conceptual and Systems Engineering perspective, a conceptual framework including the Ecosystems of System Unified Language Modeling (EoS-UML) profile, a set of Ecosystem Ensemble Diagrams, the Arms :Length Trust Model and the Cyber Physical Threat Model are provided. Second, having established this conceptual view of the ecosystem, we recognize unique role of the cryptographic credentials within it, towards enabling the ecosystem long-term value proposition and acting as a value transfer agent, implementing careful balance of properties meet stakeholder needs. Third, we propose that the ecosystem computers can be used as a distributed compute engine to run Collaborative Algorithms. To demonstrate, we define access control scheme, risk-balanced Cellular Access Control (rbCAC). The rbCAC algorithm defines access control within a cyber-physical environment in a manner which balances cost, risk, and net utility in a multi-authority setting. rbCAC is demonstrated it in an Air Travel and Border Services scenario. Other domains are also discussed included air traffic control threat prevention from drone identity attacks in protected airspaces. These contributions offer significant material for future development, ongoing credential and ecosystem design, including dynamic perimeters and continuous-time sampling, intelligent and self optimizing ecosystems, runtime collaborative platform design contracts and constraints, and analysis of APT attacks to SCADA systems using ecosystem approaches.
62

Etude et prédiction d'attention visuelle avec les outils d'apprentissage profond en vue d'évaluation des patients atteints des maladies neuro-dégénératives / Study and prediction of visual attention with deep learning net- works in view of assessment of patients with neurodegenerative diseases

Chaabouni, Souad 08 December 2017 (has links)
Cette thèse est motivée par le diagnostic et l’évaluation des maladies neuro-dégénératives et dans le but de diagnostique sur la base de l’attention visuelle.Néanmoins, le dépistage à grande échelle de la population n’est possible que si des modèles de prédiction automatique suffisamment robustes peuvent être construits. Dans ce contexte nous nous intéressons `a la conception et le développement des modèles de prédiction automatique pour un contenu visuel spécifique à utiliser dans l’expérience psycho-visuelle impliquant des patients atteints des maladies neuro-dégénératives. La difficulté d’une telle prédiction réside dans une très faible quantité de données d’entraînement. Les modèles de saillance visuelle ne peuvent pas être fondés sur les caractérisitiques “bottom-up” uniquement, comme le suggère la théorie de l’intégration des caractéristiques. La composante “top-down” de l’attention visuelle humaine devient prépondérante au fur et à mesure d’observation de la scène visuelle. L’attention visuelle peut-être prédite en se basant sur les scènes déjà observées. Les réseaux de convolution profonds (CNN) se sont révèlés être un outil puissant pour prédire les zones saillantes dans les images statiques.Dans le but de construire un modèle de prédiction automatique pour les zones saillantes dans les vidéos naturels et intentionnellement dégradées, nous avons conçu une architecture spécifique de CNN profond. Pour surmonter le manque de données d’apprentissage,nous avons conçu un système d’apprentissage par transfert dérivé de la méthode de Bengio.Nous mesurons ses performances lors de la prédiction de régions saillantes. Les r´esultatsobtenus sont int´eressants concernant la r´eaction des sujets t´emoins normaux contre leszones d´egrad´ees dans les vid´eos. La comparaison de la carte de saillance pr´edite des vid´eosintentionnellement d´egrad´ees avec des cartes de densit´e de fixation du regard et d’autresmod`eles de r´ef´erence montre l’int´erˆet du mod`ele d´evelopp´e. / This thesis is motivated by the diagnosis and the evaluation of the dementia diseasesand with the aim of predicting if a new recorded gaze presents a complaint of thesediseases. Nevertheless, large-scale population screening is only possible if robust predictionmodels can be constructed. In this context, we are interested in the design and thedevelopment of automatic prediction models for specific visual content to be used in thepsycho-visual experience involving patients with dementia (PwD). The difficulty of sucha prediction lies in a very small amount of training data.Visual saliency models cannot be founded only on bottom-up features, as suggested byfeature integration theory. The top-down component of human visual attention becomesprevalent as human observers explore the visual scene. Visual saliency can be predictedon the basis of seen data. Deep Convolutional Neural Networks (CNN) have proven tobe a powerful tool for prediction of salient areas in static images. In order to constructan automatic prediction model for the salient areas in natural and intentionally degradedvideos, we have designed a specific CNN architecture. To overcome the lack of learningdata we designed a transfer learning scheme derived from bengio’s method. We measureits performances when predicting salient regions. The obtained results are interestingregarding the reaction of normal control subjects against degraded areas in videos. Thepredicted saliency map of intentionally degraded videos gives an interesting results comparedto gaze fixation density maps and other reference models.
63

CRYSTAL PLASTICITY OF PENTAERYTHRITOL TETRANITRATE (PETN)

Jennifer Oai Lai (17677422) 24 April 2024 (has links)
<p dir="ltr">We investigate the crystal plasticity and shock response of single crystal and polycrystalline pentaerythritol tetranitrate (PETN) using mesoscale finite element simulations. The model includes the Mie-Grüneisen Equation of State and a single crystal plasticity model. Simulations with single crystals with different orientations are tested using our plasticity model under shock compression to explore shear stress and slip. Parameters regarding the Mie-Grüneisen Equation of State are also verified in various orientations from 0.50 to 1.75 km/s. A polycrystalline PETN sample with varying grain sizes and orientations are subjected to shock loading with impact velocities ranging from 0.25 to 0.75 km/s. We study how differences in shock orientation affect slip and stress in PETN at different shock strengths.</p>

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