• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 448
  • 58
  • 38
  • 35
  • 24
  • 14
  • 11
  • 9
  • 5
  • 3
  • 2
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 750
  • 750
  • 240
  • 179
  • 126
  • 118
  • 111
  • 110
  • 99
  • 93
  • 79
  • 65
  • 65
  • 65
  • 62
  • 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.
381

Técnicas de testes aplicadas a software embarcado em redes ópticas / Tests techniques applied to embedded software in optical networks

Fadel, Aline Cristine, 1984- 19 August 2018 (has links)
Orientadores: Regina Lúcia de Oliveira Moraes, Eliane Martins / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-19T14:09:37Z (GMT). No. of bitstreams: 1 Fadel_AlineCristine_M.pdf: 3259764 bytes, checksum: a287ca33254d027f23e2f2f818464ee1 (MD5) Previous issue date: 2011 / Resumo: Esse trabalho apresenta os detalhes e os resultados de testes automatizados e manuais que utilizaram a técnica de injeção de falhas e que foram aplicados em redes ópticas. No primeiro experimento o teste foi automatizado e utilizou a emulação de falhas físicas baseadas na máquina de estados do software embarcado dessa rede. Para esse teste foi utilizado uma chave óptica que é controlada por um robô de testes. O segundo experimento foi um teste manual, que injetou falhas nas mensagens de comunicação do protocolo dessa rede, a fim de validar os mecanismos de tolerância a falhas do software central dessa rede. Esse experimento utilizou a metodologia Conformance and Fault injection para preparar, executar e relatar os resultados dos casos de testes. Nos dois experimentos também foi utilizado um padrão de documentação de testes que visa facilitar a reprodução dos testes, a fim de que eles possam ser aplicados em outros ambientes. Com a aplicação desses testes, a rede óptica pode alcançar uma maior confiabilidade, disponibilidade e robustez, que são características essenciais para sistemas que requerem alta dependabilidade / Abstract: This work presents the details and the results of automatic and manual tests that used the fault injection technique and were applied on GPON network. In the first experiment the test was automated, and it performed the emulation of physical faults based on the state machine of the embedded software in this network. In this test is used an optical switch that is controlled by a test robot. The second experiment was a manual test, which injected faults on protocol communication message exchanged through the optical network, in order to validate the main software fault tolerance mechanisms. This experiment used a Conformance and Fault injection methodology to prepare, execute and report the results of the test cases. In both experiments, it was used a standard test documentation to facilitate the reproduction of the tests, so that they can be applied in other environments. With applying both tests, the optical networks reach greater reliability, availability and robustness. These attributes are essential for systems that require high dependability / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia
382

Evaluation of a diagnostic tool for use during system development and operations

Andersson, Daniel, Sköld, Patrik January 2007 (has links)
Rodon is a diagnostic tool developed by Sörman. SAAB’s interest in Rodon regards the possibility to use the tool for development and operations of aircraft systems. The main goal of this thesis was to evaluate the capacity of Rodon and determine how SAAB can use the diagnostic tool during development and operations. The tool uses model based diagnosis with artificial intelligence for fault isolation which is a powerful approach. If Rodon is introduced at SAAB, then detailed models of systems will be necessary to create, including the nominal behavior of the system and different faulty behaviors. In order to achieve high quality fault isolation, it is necessary to have complete and consistent models. To be able to use all applications that Rodon feature for a modeled system, preferable characteristics are that the model should be static, have discrete control signals, and have well defined system behavioral modes. During development of a system Rodon can be used to improve and easy the work for failure analysis, guidance of sensor placements, evaluation of tests, generation of decision structures, and fault isolation. Since design of tests during development is a desirable application that Rodon does not have, two different methods are presented that utilizes Rodon to generate all possible limit checking tests. In conclusion, Rodon can be very useful in several different aspects if introduced, but benefits gained by using Rodon will have to be compared to the labor cost of creating good models.
383

Facial Features Tracking using Active Appearance Models

Fanelli, Gabriele January 2006 (has links)
This thesis aims at building a system capable of automatically extracting and parameterizing the position of a face and its features in images acquired from a low-end monocular camera. Such a challenging task is justified by the importance and variety of its possible applications, ranging from face and expression recognition to animation of virtual characters using video depicting real actors. The implementation includes the construction of Active Appearance Models of the human face from training images. The existing face model Candide-3 is used as a starting point, making the translation of the tracking parameters to standard MPEG-4 Facial Animation Parameters easy. The Inverse Compositional Algorithm is employed to adapt the models to new images, working on a subspace where the appearance is "projected out" and thus focusing only on shape. The algorithm is tested on a generic model, aiming at tracking different people’s faces, and on a specific model, considering one person only. In the former case, the need for improvements in the robustness of the system is highlighted. By contrast, the latter case gives good results regarding both quality and speed, with real time performance being a feasible goal for future developments.
384

Modélisation des dépendances fonctionnelles pour l'analyse des risques de niveau avion / Functional dependencies modelling for aircraft level risk analysis

Maîtrehenry, Sébastien 04 October 2013 (has links)
Nos travaux se situent au croisement de trois domaines : la sûreté de fonctionnement, l'analysefonctionnelle et l'ingénierie des modèles. Dans l'objectif d'assister les analyses préliminaires desrisques, nous avons proposé d'exploiter les modèles issus de l'analyse fonctionnelle de l'avion. Cesmodèles décrivent les dépendances entre les fonctions qui doivent être réalisées durant une phasede vol. Pour exploiter ces modèles, nous avons introduit la notion d'efficacité qui mesure ledegré de contribution d'une fonction à la réalisation nominale d'une phase de vol. Cette notionest utile pour les analyses de risques car elle permet de formaliser divers cas dedysfonctionnements des fonctions et pour évaluer le niveau de dégradation d'une phase de vol encas de dysfonctionnement d'une ou plusieurs fonctions. Nous avons proposé d'annoter les modèlesissus de l'analyse fonctionnelle avec des informations relatives à l'efficacité des fonctions et à leursdysfonctionnements possibles. En suivant les principes de la transformation de modèles, nousavons étudié les moyens de produire le plus automatiquement possible des modèles utiles auxanalyses de risques à partir des modèles annotés. Les modèles produits sont décrits avec lelangage AltaRica, ils peuvent être analysés avec les outils associés à ce langage afin d'évaluerl'effet du dysfonctionnement de fonctions de l'avion ou de rechercher les combinaisons dedysfonctionnements les plus critiques. L'approche proposée a été appliquée pour analyser lesrisques associés aux fonctions utiles lors du décollage d'un avion. / Our work links three domains: safety, functional analysis and model based engineering. In orderto assist preliminary risk analysis, we have proposed to exploit models developed for functionalanalysis. These models describe dependencies between functions that have to be performed duringa flight phase. To exploit these models, we have introduced the notion of efficiency thatmeasures the degree of contribution of a function to the nominal realisation of a flight phase.This notion is useful for risk analysis because it enables the formalisation of various cases offunction failures and the evaluation of the level of degradation of a flight phase in case offunction failures. We have proposed to annotate functional analysis models with informationrelated with function efficiency and potential function failures. Following the principles of modeltransformation, we have studied the means to produce as automatically as possible models thatcould be used to support risk analysis starting from annotated models. Produced models aredescribed with the AltaRica language, they can be analysed with the tools associated with thislanguage in order to evaluate the effect of function failures or to search for the most criticalcombinations of failures. The approach was applied in order to analyse the risks associated withthe functions used during an aircraft take-off.
385

Identifying mixtures of mixtures using Bayesian estimation

Malsiner-Walli, Gertraud, Frühwirth-Schnatter, Sylvia, Grün, Bettina January 2017 (has links) (PDF)
The use of a finite mixture of normal distributions in model-based clustering allows to capture non-Gaussian data clusters. However, identifying the clusters from the normal components is challenging and in general either achieved by imposing constraints on the model or by using post-processing procedures. Within the Bayesian framework we propose a different approach based on sparse finite mixtures to achieve identifiability. We specify a hierarchical prior where the hyperparameters are carefully selected such that they are reflective of the cluster structure aimed at. In addition, this prior allows to estimate the model using standard MCMC sampling methods. In combination with a post-processing approach which resolves the label switching issue and results in an identified model, our approach allows to simultaneously (1) determine the number of clusters, (2) flexibly approximate the cluster distributions in a semi-parametric way using finite mixtures of normals and (3) identify cluster-specific parameters and classify observations. The proposed approach is illustrated in two simulation studies and on benchmark data sets.
386

Advancing Towards Model-Based Decision-Making : A Qualitative Case Study at a Swedish Whisky Start-Up

Nerbel, Jan Frederic, Hammarsten, Ellinor, Hedlund, Tobias January 2017 (has links)
This study investigates decision-making processes in respect to the maturation time and the marketed quantities of single malt whisky in a Swedish distillery start-up. At first, the literature regarding decision-making in both start-ups and larger organisations has been reviewed. It can be concluded that decision-making in start-ups, compared to their established counterparts, is more based on heuristics and continuously exposed to several biases. In the following, a general resource exploitation model is presented in the context of deterministic decision-making and adjusted towards whisky casks as deposits of nonrenewable resources. The consecutive case study is conducted in a Swedish distillery start-up. Findings indicate that the start-up is exposed to a high market dynamic and expert-knowledge is of high importance. In the start-up, these experts make decisions regarding the maturation times and the quantities of the marketed whisky. Nevertheless, the optimal exploitation model can be implemented into daily operations and delivers additional data for decisions. Planning can evolve from a mainly cost-based towards a profit-maximising perspective. However, the quality of the model results are expected to be limited, due to the deterministic nature of the model in a highly dynamic environment. This effect may be even amplified by input parameters, which cannot be precisely determined.Therefore, the industry knowledge of the decision-maker appears to be the most important factor for decision-making processes in this industry.
387

Commande prédictive pour la réalisation de tâches d'asservissement visuel successives / Predictive control for the achievement of successive visual servoing tasks

Cazy, Nicolas 29 November 2016 (has links)
On rencontre aujourd'hui la vision par ordinateur employée pour la réalisation de nombreuses applications de la robotique moderne. L'un des axes de recherche actuel qui tend à améliorer ces systèmes est centré sur la commande. L'objectif est de proposer des schémas de commande originaux permettant de lier efficacement les informations mesurées par les capteurs de vision aux actions que l'on souhaite réaliser avec les robots. C'est dans cet aspect que s'inscrit ce document en apportant de nouvelles méthodes à la commande robotique classique faisant intervenir la vision, l'asservissement visuel. Le cas de pertes d'informations visuelles pendant la réalisation d'une tâche d'asservissement visuel est étudié. Dans ce sens, deux méthodes de prédiction qui permettent à la tâche d'être réalisée malgré ces pertes sont présentées. Puis une méthode inédite de correction est proposée. Celle-ci permet d'obtenir de meilleurs résultats de prédiction qu'une méthode classique, comme le démontrent des résultats obtenus en simulation et en condition réelle. Enfin, dans le contexte de la réalisation de plusieurs tâches d'asservissement visuel successives, une nouvelle méthode est présentée. Celle-ci exploite les caractéristiques d'un schéma de commande utilisé depuis quelques dizaines d'années dans l'industrie et la recherche, la commande prédictive basée modèle. Des résultats obtenus en simulation proposent de visualiser les effets de cette méthode sur le comportement d'un drone qui embarque une caméra. / The computer vision is used for the achievement of many applications of modern robotics. One of the current research topics that aims to improve these systems is focused on command. The objective consists to propose original control schemes to effectively link the information measured by the vision sensor to the actions that are to be achieved with the robots. This document is part of this look by bringing new methods to classical robotic control involving vision, the visual servoing.The case of visual information losses during the achievement of a visual servoing task is studied. In this sense, two prediction methods that allow the task to be achieved despite these losses are presented. Then a new method of correction is proposed. This provides better prediction results than a conventional method, as shown by the results obtained in simulation and in real conditions.Finally, in the context of the achievement of several successive visual servoing tasks, a new method is presented. This exploits the characteristics of a control scheme used for several decades in industry and research, model based predictive control. The results obtained in simulation propose to see the effect of this method on the behavior of a drone that embeds a camera.
388

A simulation-driven model-based approach for designing software-intensive systems-of-systems architectures / Uma abordagem digirida por simulação e baseada em modelos para projeto de arquiteturas de sistemas de sistemas intensivos em software

Valdemar Vicente Graciano Neto 27 March 2018 (has links)
Context: Software-intensive systems have been increasingly interoperated forming alliances termed as Systems-of-Systems (SoS). SoS comprises a collection of systems joined to achieve a set of missions that none of the systems can accomplish on its own. Each constituent system keeps its own management, goals, and resources while coordinating within the SoS and adapting to meet SoS goals. Applications of SoS range from traffic control to emergency response and crisis management. As SoS often support critical domains, such systems must be correct by dealing with malfunction or defects and avoiding failures that could cause extensive damage and losses to the users. Problem: Correct SoS operations depend on a precise specification and a rigorous attestation of its operational consistency. However, besides limitations on languages to jointly capture SoS structure and behavior, predictions on the SoS operational consistency rely on constituent systems not totally known at design-time. Therefore, SoS have been developed and deployed without evaluating their operations, since current languages do not support such precision in evaluation. Objectives: This thesis provides solutions founded on a formal architectural description language to support an early evaluation of SoS operation regarding SoS structure and behavior by means of simulations. Contribution: The main contributions of this project comprise (i) a model transformation approach for automatically producing simulation models from SoS software architecture descriptions, combining SoS structure and behavior description in a same solution, (ii) a SoS software architecture evaluation method for SoS operation prediction considering the inherent changes that can occur, (iii) environment modelling and automatic generation of stimuli generators to sustain the SoS simulation, delivering data to feed such simulation, and (iv) a method for the automatic synchronization between the runtime descriptive architecture (changed at runtime due to dynamic architecture) and its original prescriptive architecture based on model discovery and recovery mechanisms and a backward model transformation. Evaluation: We conducted case studies to assess our solutions using Flood Monitoring SoS and Space SoS. Results: Our solutions support a high accuracy to (i) produce fault-free and fully operational simulations for SoS software architectures, (ii) support evaluation and prediction of SoS operation at design-time, (iii) automatically generate stimuli generators to sustain and feed the simulation execution, and (iv) maintain the synchronization between the runtime architecture and the intended version of the SoS architecture. Conclusions: We concluded that the proposed solutions advance the state of the art in SoS software architecture evaluation by offering solutions to predict the SoS operations effectiveness to maintain a continuous operation despite architectural changes, providing more trust for users that futurely shall rely on SoS services. / Contexto: Sistemas intensivos em software tem sido interoperados para formar alianças conhecidas como Sistemas-de-Sistemas (SoS). Domínios de aplicação de SoS variam do controle de tráfego ao gerenciamento de situações de crises e emergência. Devido à criticidade destes domínios, tais sistemas precisam ser confiáveis e robustos, lidando com potenciais defeitos e mal funcionamento, e evitando falhas que poderiam causar ameaças à integridade dos usuários. Problema: O funcionamento correto de um SoS depende da especificação precisa e da garantia rigorosa da consistência de suas operações. Entretanto, além das limitações nas linguagens quanto à especificação de ambos estrutura e comportamento do SoS, prever seu comportamento depende da especificação de constituintes que não são totalmente conhecidos em tempo de projeto e de seu comportamento emergente. Neste sentido, SoS têm sido desenvolvidos e implantados sem a devida avaliação de seus comportamentos, uma vez que as linguagens disponíveis atualmente não dão suporte a uma especificação precisa destes comportamentos. Objetivos: Este projeto de doutorado relata avanços teóricos e práticos fundamentados em uma linguagem de descrição arquitetural formal para permitir a predição e avaliação do comportamento e estrutura dos SoS com base em simulações. Contribuições: As principais contribuições deste projeto envolvem (i) uma transformação de modelos para produzir automaticamente modelos de simulação para descrições de arquitetura de software de SoS, combinando estrutura e comportamento em uma mesma solução, (ii) um método de avaliação de arquitetura de software de SoS para prever o comportamento do SoS considerando sua dinâmica inerente, (iii) modelagem do ambiente e derivação automática de geradores de estímulos entregando dados continuamente e sustentando a execução de simulações de SoS, e (iv) um método para promover a sincronização automática entre modelos descritivos e prescritivos de arquitetura de software de SoS baseados em mecanismos de descoberta e recuperação de modelos, e transformação de modelos reversa. Avaliação: Estudos de caso foram conduzidos para avaliar as soluções nos domínios de Monitoramento de Enchentes e Espacial. Resultados: As abordagens propostas exibem alta acurácia no que tange (i) a produzir simulações operacionais e sem falhas para arquiteturas de software de SoS, (ii) ao suporte á avaliação, ainda em tempo de projeto, do comportamento que emerge da operação do SoS, (iii) à derivação automática de geradores de estímulos para entrega contínua de dados e manutenção da execução das simulações geradas, e (iv) à manutenção do alinhamento entre os modelos descritivos e prescritivos da arquitetura do SoS avaliado. Conclusões: Conclui-se que as abordagens propostas avançam o estado da arte no projeto de arquiteturas de Software de SoS ao permitir prever, em tempo de projeto, como o SoS vai operar em tempo de execução, permitindo estabelecer estratégias para manter a simulação rodando, e sua operação contínua, mesmo com as mudanças arquiteturais inerentes ao seu funcionamento, provendo mais confiabilidade para os usuários futuramente dependerão de seus serviços.
389

HIL testovací stav pro soustavu univerzálních elektronických řídících jednotek / HIL test stand for universal electronic control units

Zouhar, Štěpán January 2019 (has links)
This diploma thesis is focused on testing of Electronic Control Units, especially functional testing in which hardware and software is verified and also Model in the Loop, Software in the Loop, Processor in the Loop and Hardware in the Loop testing methods. Within practical part of this thesis testing stand for functional test of the ECU was developed and manufactured. It is connected to PC via Input/Output card, testing is controlled by MATLAB script. Whole process of testing is automated from initial upload of testing firmware to tested ECU over all phases of test up to bootloader flashing. Hardware in the Loop test was also created, in which ECU works as controller and DC motor is simulated in real time with PC in MATLAB environment.
390

Automated Modeling of Human-in-the-Loop Systems

Noah M Marquand (11587612) 22 November 2021 (has links)
Safety in human in the loop systems, systems that change behavior with human input, is difficult to achieve. This difficulty can cost lives. As desired system capability grows, so too does the requisite complexity of the system. This complexity can result in designers not accounting for every use case of the system and unintentionally designing in unsafe behavior. Furthermore, complexity of operation and control can result in operators becoming confused during use or receiving insufficient training in the first place. All these cases can result in unsafe operations. One method of improving safety is implementing the use of formal models during the design process. These formal models can be analyzed mathematically to detect dangerous conditions, but can be difficult to produce without time, money, and expertise.<br> This document details the study of potential methods for constructing formal models autonomously from recorded observations of system use, minimizing the need for system expertise, saving time, money, and personnel in this safety critical process. I first discuss how different system characteristics affect system modeling, isolating specific traits that most clearly affect the modeling process Then, I develop a technique for modeling a simple, digital, menu-based system based on a record of user inputs. This technique attempts to measure the availability of different inputs for the user, and then distinguishes states by comparing input availabilities. From there, I compare paths between states and check for shared behaviors. I then expand the general procedure to capture the behavior of a flight simulator. This system more closely resembles real-world safety critical systems and can therefore be used to approximate a real use case of the method outlined. I use machine learning tools for statistical analysis, comparing patterns in system behavior and user behaviors. Last, I discuss general conclusions on how the modeling approaches outlined in this document can be improved and expanded upon.<br> For simple systems, we find that inputs alone can produce state machines, but without corresponding system information, they are less helpful for determining relative safety of different use cases than is needed. Through machine learning, we find that records of complex system use can be decomposed into sets of nominal and anomalous states but determining the causal link between user inputs and transitions between these conditions is not simple and requires further research.

Page generated in 0.0906 seconds