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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.
51

Détection de rails, caractérisation de croisements et localisation de trains sur la trajectoire d'un métro automatique

Corsino Espino, Jorge 13 June 2014 (has links) (PDF)
Cette thèse porte sur la fonction de détection d'obstacles dans le domaine ferroviaire à partir de la vision par ordinateur. Il s'agit d'assurer une perception de l'environnement situé à l'avant du train afin de détecter et d'évaluer les distances des obstacles situés sur la voie.Nous avons donc proposé un module détection de rails à partir des images à niveaux de gris, pour déterminer une zone libre d'obstacles à l'avant du train. Cette détection est basée dans l'algorithme de RANSAC et une estimation de la voie par un polynôme de degré 2. Elle s'est montrée robuste à notre base de données et a permis de détecter les rails à des distances supérieures à la distance d'arrêt. Aussi, un algorithme d'étalonnage des caméras installées dans le train a été proposé à partir de la morphologie de la voie.Comme support de la reconnaissance de rails, nous présentons un module de détection et classification des appareils de voie basé dans le descripteur HOG extrait des images IPM (Inverse Perspective Mapping). Un classifieur SVM (Support Vector Machines) binaire a été utilisé pour la détection et un SVM multi-classe pour différencier les appareils de voie existants sur la ligne.Après avoir élaboré le module de détection des rails, nous avons implémenté un détecteur de trains. À partir d'un échantillon des images de trains de la ligne en question et des images négatives comme des voitures ou des bus, nous avons créé une base de données d'obstacles pour trouver un descripteur robuste qui arrive à décrire la forme des trains et permet à un classifieur SVM de discriminer les images et détecter les trains. Par la suite, ce classifieur est utilisé par le système global pour déterminer la présence d'un train au-delà de la détection de la voie. À la distance maximale de détection, un rectangle de la taille d'un train est extrait de l'image pour vérifier la présence d'un train. Ces rectangles font l'objet d'une classification au moyen de descripteurs globaux de type HOG et une structure SVM binaire.Cette étude permettra non seulement de déboucher sur des applications concrètes, mais surtout d'évaluer la maturité des technologies de traitements d'images pour réaliser des fonctions sûres appliquées aux systèmes ferroviaires.
52

Enabling loop-closures and revisits in active SLAM techiniques by using dynamic boundary conditions an local potential distortions / Viabilizante fechamento de ciclos e revistas técnicas de SLAM ativo usando condições de contorno dinâmicas e distorções de potencial locais

Jorge, Vitor Augusto Machado January 2017 (has links)
Robôs verdadeiramente autônomos devem conhecer o ambiente para executar tarefas complexas. Em ambientes desconhecidos o robô deve concorrentemente construir o mapa do ambiente e se localizar usando sensores proprioceptivos e exteroceptivos imprecisos. Isto é problemático, uma vez que o mapa parcial e possivelmente incorreto do ambiente será usado para corrigir erros de localização. Este problema importante da robótica móvel é conhecido como Localização e Mapeamento Simultâneos (SLAM). Quando um robô autonomamente executa o algoritmo de SLAM concorrentemente com uma estratégia de exploração, o problema passa a se chamar SLAM Ativo ou Exploração Integrada. Um dos principais desafios por trás destes problemas é o tratamento de fechamento de ciclos. Ao atravessar regiões desconhecidas ou ambientes esparsos, a pose do robô e o mapa podem não ser propriamente corrigidos por falta de informação. Quando isto acontece, as incertezas da posição do robô e do mapa aumentam, podendo levar a erros irrecuperáveis. Por outro lado, quando o ciclo é fechado corretamente, estas incertezas diminuem consideravelmente. Portanto, a escolha do caminho para explorar o ambiente pode drasticamente melhorar ou degradar a qualidade do mapeamento e da localização. Uma técnica bem conhecida de exploração de ambientes é a adaptação do problema de valor de contorno (BVP) para a equação de Laplace e condições de contorno de Dirichlet. Apesar de ser fácil de implementar, resultando em trajetórias de exploração suaves, esta técnica não endereça cuidadosamente erros de SLAM, uma vez que ela segue a descida do gradiente, o que pode não possibilitar revisitas, uma limitação crucial para o SLAM Ativo. Mesmo sendo uma técnica de exploração gulosa e direcionada a fronteiras, consideramos que a flexibilidade do BVP e condições de contorno de Dirichlet ainda são pouco exploradas. Nossa proposta é modificar o algoritmo de Exploração por BVP para executar comportamentos complexos, tais como revisitas e, em particular, fechamentos de ciclo. Apresentamos duas novas abordagens: a primeira faz uso de uma condição de contorno direcionada pelo tempo combinada a distorções de potencial para gerar comportamentos de fechamento de ciclo, além de um potencial que nunca cessa de existir, mesmo após o ambiente ter sido completamente explorado; a segunda, propicia o fechamento de ciclos aproveitando a propagação do potencial em regiões desconhecidas, através de um par dinâmico de condições de contorno que funcionam como obstáculos e objetivos virtuais. Ambas abordagens aproveitam o Esqueleto de Voronoi do ambiente para reduzir o custo computacional do algoritmo. Testes em ambientes reais e simulados usando o robô Pioneer 3DX mostram que as técnicas apresentadas apresetam melhores resultados quando comparadas a técnicas concorrentes. / Truly autonomous robots must know the environment in order to execute complex tasks. In unknown environments, the robot must construct a map and localize itself using noisy proprioceptive and exteroceptive sensors. This is problematic, since the partial and possibly inaccurate map of the environment will be used to correct localization errors. This important problem of mobile robotics is known as Simultaneous Localization and Mapping (SLAM). When a robot autonomously execute a SLAM algorithm concurrently with an exploration strategy, this problem is called Active SLAM or Integrated Exploration. One of the main challenges behind both these problems is the treatment of loop closures. While the robot traverses unknown regions or sparse environments, the robot pose and the map may not be properly corrected due to lack of information. When this happens, the uncertainties about the map and the robot pose increase, which may lead to unrecoverable SLAM errors. On the other hand, when a loop is closed successfully, these uncertainties drastically decrease. Therefore, path chosen to explore the environment can considerably improve or degrade the quality of both localization and mapping. One well known way to explore the environment is the adaptation of the Boundary Value Problem (BVP) for the Laplace Equation and Dirichlet boundary conditions. Even though it is easy to implement, resulting in smooth exploration trajectories, it does not carefully address SLAM errors, since it follows a gradient decent which not always allows revisits, a crucial limitation for Active SLAM. Despite being a greedy frontier driven exploration strategy, we consider the flexibility of the BVP and Dirichlet boundary conditions still under-explored for Active SLAM. Our proposal is to modify the BVP Exploration algorithm to execute complex exploration behaviors, such as revisits and, in particular, loop-closures. We present two new approaches: the first makes use of a time driven boundary value condition together with potential distortions to generate loop closing behaviors and a potential field that never ceases to exist, even after the exploration ends; the second enables loop closure behaviors with BVP by taking advantage of potential propagation in unknown space generated by a pair of dynamic boundary conditions functioning as virtual walls and goals. Both approaches take advantage of a local optimization that uses the Voronoi Skeleton to reduce the computational cost of the algorithm. Tests in real and simulated environments using a Pioneer 3DX show that the proposed approaches present better results when compared with competing approaches.
53

Enabling loop-closures and revisits in active SLAM techiniques by using dynamic boundary conditions an local potential distortions / Viabilizante fechamento de ciclos e revistas técnicas de SLAM ativo usando condições de contorno dinâmicas e distorções de potencial locais

Jorge, Vitor Augusto Machado January 2017 (has links)
Robôs verdadeiramente autônomos devem conhecer o ambiente para executar tarefas complexas. Em ambientes desconhecidos o robô deve concorrentemente construir o mapa do ambiente e se localizar usando sensores proprioceptivos e exteroceptivos imprecisos. Isto é problemático, uma vez que o mapa parcial e possivelmente incorreto do ambiente será usado para corrigir erros de localização. Este problema importante da robótica móvel é conhecido como Localização e Mapeamento Simultâneos (SLAM). Quando um robô autonomamente executa o algoritmo de SLAM concorrentemente com uma estratégia de exploração, o problema passa a se chamar SLAM Ativo ou Exploração Integrada. Um dos principais desafios por trás destes problemas é o tratamento de fechamento de ciclos. Ao atravessar regiões desconhecidas ou ambientes esparsos, a pose do robô e o mapa podem não ser propriamente corrigidos por falta de informação. Quando isto acontece, as incertezas da posição do robô e do mapa aumentam, podendo levar a erros irrecuperáveis. Por outro lado, quando o ciclo é fechado corretamente, estas incertezas diminuem consideravelmente. Portanto, a escolha do caminho para explorar o ambiente pode drasticamente melhorar ou degradar a qualidade do mapeamento e da localização. Uma técnica bem conhecida de exploração de ambientes é a adaptação do problema de valor de contorno (BVP) para a equação de Laplace e condições de contorno de Dirichlet. Apesar de ser fácil de implementar, resultando em trajetórias de exploração suaves, esta técnica não endereça cuidadosamente erros de SLAM, uma vez que ela segue a descida do gradiente, o que pode não possibilitar revisitas, uma limitação crucial para o SLAM Ativo. Mesmo sendo uma técnica de exploração gulosa e direcionada a fronteiras, consideramos que a flexibilidade do BVP e condições de contorno de Dirichlet ainda são pouco exploradas. Nossa proposta é modificar o algoritmo de Exploração por BVP para executar comportamentos complexos, tais como revisitas e, em particular, fechamentos de ciclo. Apresentamos duas novas abordagens: a primeira faz uso de uma condição de contorno direcionada pelo tempo combinada a distorções de potencial para gerar comportamentos de fechamento de ciclo, além de um potencial que nunca cessa de existir, mesmo após o ambiente ter sido completamente explorado; a segunda, propicia o fechamento de ciclos aproveitando a propagação do potencial em regiões desconhecidas, através de um par dinâmico de condições de contorno que funcionam como obstáculos e objetivos virtuais. Ambas abordagens aproveitam o Esqueleto de Voronoi do ambiente para reduzir o custo computacional do algoritmo. Testes em ambientes reais e simulados usando o robô Pioneer 3DX mostram que as técnicas apresentadas apresetam melhores resultados quando comparadas a técnicas concorrentes. / Truly autonomous robots must know the environment in order to execute complex tasks. In unknown environments, the robot must construct a map and localize itself using noisy proprioceptive and exteroceptive sensors. This is problematic, since the partial and possibly inaccurate map of the environment will be used to correct localization errors. This important problem of mobile robotics is known as Simultaneous Localization and Mapping (SLAM). When a robot autonomously execute a SLAM algorithm concurrently with an exploration strategy, this problem is called Active SLAM or Integrated Exploration. One of the main challenges behind both these problems is the treatment of loop closures. While the robot traverses unknown regions or sparse environments, the robot pose and the map may not be properly corrected due to lack of information. When this happens, the uncertainties about the map and the robot pose increase, which may lead to unrecoverable SLAM errors. On the other hand, when a loop is closed successfully, these uncertainties drastically decrease. Therefore, path chosen to explore the environment can considerably improve or degrade the quality of both localization and mapping. One well known way to explore the environment is the adaptation of the Boundary Value Problem (BVP) for the Laplace Equation and Dirichlet boundary conditions. Even though it is easy to implement, resulting in smooth exploration trajectories, it does not carefully address SLAM errors, since it follows a gradient decent which not always allows revisits, a crucial limitation for Active SLAM. Despite being a greedy frontier driven exploration strategy, we consider the flexibility of the BVP and Dirichlet boundary conditions still under-explored for Active SLAM. Our proposal is to modify the BVP Exploration algorithm to execute complex exploration behaviors, such as revisits and, in particular, loop-closures. We present two new approaches: the first makes use of a time driven boundary value condition together with potential distortions to generate loop closing behaviors and a potential field that never ceases to exist, even after the exploration ends; the second enables loop closure behaviors with BVP by taking advantage of potential propagation in unknown space generated by a pair of dynamic boundary conditions functioning as virtual walls and goals. Both approaches take advantage of a local optimization that uses the Voronoi Skeleton to reduce the computational cost of the algorithm. Tests in real and simulated environments using a Pioneer 3DX show that the proposed approaches present better results when compared with competing approaches.
54

Soldagem de trilhos ferroviários perlíticos: origem das microestruturas. / Welding of pearlitic railroad rails: origins of microstructures.

Lucas Pintol Nishikawa 04 May 2018 (has links)
Este estudo analisou, em um primeiro momento, soldas de trilhos perlíticos para carga pesada soldados pelo processo aluminotérmico e solda topo com centelhamento (Flash butt-weld) focando nas alterações macro e microestruturais, bem como alterações de dureza decorrentes do processo. Uma junta em situação de uso real também foi estudada comparando-se o comportamento de deformação e desgaste à condição sem uso. Todos os casos apresentaram comportamento semelhante na zona afetada pelo calor possuindo perda de dureza em região de microestrutura esferoidizada. A origem desta estrutura foi, então, discutida. A formação de esferoidização pelo fenômeno de redução de energia de interface por movimentação de interfaces sólidas é considerado incompatível com os tempos dos processos utilizados. A hipótese de formação da zona esferoidizada por transformação do eutetóide divorciado (Divorced Eutectoid Transformation, DET) foi testada por meio de simulações de ciclos térmicos em dilatômetro de têmpera, para três diferentes aços. Com base nos resultados é seguro afirmar que o processo envolvido na esferoidização ao final da zona afetada pelo calor de trilhos perlíticos soldados é, de fato, a transformação do eutetóide divorciado. Confirmando esta hipótese, observa-se que o aumento do teor de carbono nos trilhos aumenta a faixa de esferoidização. / This work analyzed, initially, pearlitic heavy haul rail thermite welds and flash buttwelds, focusing in macro and microstructural changes as well as hardness changes occurring due to the processes. A weld in real use was also studied comparing the deformation behavior and wear to the unused condition. All cases presented similar behavior at the heat-affected zone with hardness loss associated to a spheroidized microstructure. The mechanisms for the formation of this structure, was discussed. The spheroidization by solid interface movement, driven by interface energy reduction, is not compatible with the processing times for welding. The hypothesifs of spheroidized region formation by a divorced eutectoid transformation (DET) was tested by simulated heat-treatments using a dilatometer and three different steels. Based on that it is safe to conclude that the process for the formation of an spheroidized zone at the end of the heat-affected zone on welded pearlitic rails is, indeed, the divorced eutectoid transformation. Furthermore, the carbon content was shown to increase spheroidization range.
55

Fac tExtraction For Ruby On Rails Platform

Tshering, Nima January 2010 (has links)
In the field of software engineering, software architecture plays an important role particularly in areas of critical and large-scale software system development and over the years it has evolved as an important sub-discipline within the field of software engineering. However, software architecture is still an emerging discipline mainly attributed by the lack of standardized way for architectural representation and also due to lack of analysis methods that can determine if the intended architecture translates into correct implementation during the software development [HNS00]. Architecture compliance checking [KP07] is a technique used to resolve latter part of the problem and Fraunhofer SAVE (Software Architecture Visualization and Evaluation) is a compliance-checking tool that uses fact extraction. This master’s thesis provides fact extraction support to Fraunhofer SAVE for a system developed using Ruby on Rail framework by developing a fact extractor. The fact extractor was developed as an eclipse plug-in in Java that was integrated with SAVE platform, it consists of a parser that parses Ruby source code and then generates an abstract syntax tree. The architectural facts are extracted by analyzing these abstract syntax trees using a visitor pattern from which architecture of the system are generated. It is represented using the internal model of the SAVE platform. The fact extractor was validated using two reference systems of differing sizes developed using Ruby on Rails framework. A reference system with smaller size, which contains all the relevant Ruby language constructs, was used to evaluate correctness and completeness of the fact extractor. The evaluation result showed the correctness value of 1.0 or 100% and completeness value of 1.0 or 100%. Afterwards, a larger application with more complex architecture was used to validate the performance and robustness of the fact extractor. It has successfully extracted, analyzed and build the SAVE model of this large system by taking 0.05 seconds per component without crashing. Based these computations, it was concluded that the performance of the fact extractor was acceptable as it performed better than C# fact extractor.
56

Mobile Service For the Olympic Games 2008

Silva, Lakmal, Xin, Yu January 2008 (has links)
Mobile tourism service applications can be developed and successfully deployed with the rapid developments in mobile phones, communication technologies and tourism. In many situations, when travelers visit a country for a special event or just as travelers, it is obvious that they want to utilize the time and resources efficiently to enjoy the events and visit many places as possible. To achieve this, a traveler needs variety of information to make decisions and travel plans. Traditionally, this means purchasing tour guide books about a county or a city that refer them. At the same time, the 29th Olympic game is coming to the oldest civilized country China in 2008. The goal of our mobile service is to provide needed tourist information of the host country as well as event specific information. In the case of traveling for a special event, it is crucial to be informed about the last minute changes in the schedules. Our implementation tries to address these issues as much as possible.
57

Rekonstruktion och optimering av laddningstid för en webbsida i Ruby on Rails

Andréasson, Dan, Morja, Daniel January 2015 (has links)
Många verksamheter representeras idag på internet i omodern stil vilket kan påverka besökarens uppfattning om verksamheten negativt. I detta arbete har en webbsida rekonstruerats. Webbsidan tillhör en förening med verksamhet inom gaming och esport. Rekonstruktionen är till för att ge besökare en klar bild av vad föreningens huvudverksamhet är och för att integrera streamingtjänsten Twitch för att ge besökare ytterligare en anledning att återbesöka sidan. Dessutom har laddningstiden för startsidan optimerats för att ge bättre besökupplevelse. Med hjälp av Redis och metoden Eager loading visar arbetet hur man kan sänka laddningstiden på en webbsida.
58

Automated testing of a dynamic web application

Olofsson, Niclas January 2014 (has links)
Software testing plays an important role in the process of verifying software functionality and preventing bugs in production code. By writing automated tests using code instead of conducting manual tests, the amount of tedious work during the development process can be reduced and the software quality can be improved. This thesis presents the results of a conducted case study on how automated testing can be used when implementing new functionality in a Ruby on Rails web application. Different frameworks for automated software testing are used as well as test-driven development methodology, with the purpose of getting a broad perspective on the subject. This thesis studies common issues with testing web applications, and discuss drawbacks and advantages of different testing approaches. It also looks into quality factors that are applicable for tests, and analyze how these can be measured.
59

Využití Ruby on Rails pro podporu týmové spolupráce vývojářů / Using Ruby on Rails for supporting team collaboration of developers

Hofmann, Petr January 2008 (has links)
Thema of this master thesis is Using Ruby on Rails for support of team collaboration of developers. The main objective is support of team collaboration of developers (students of programming courses) at the Catedry of Computer Science of the University of Economics Prague. The objective has been acomplished by developement of a new application in Ruby on Rails on the school server kitscm.vse.cz. This application is used for support of team collaboration. Application automatizes some of procedures, which were made on the server kitscm.vse.cz manually in the past. Application collaborates with another open-source applications (openldap, dokuwiki, subversion) running on the kitscm.vse.cz server. After the introduction (chapter 1), follows familiarization with Ruby and Ruby on Rails (chapter 2), analysis and design of the application (chapter 3), familirization with application operational architecture (chapter 4) and example of development of part of the application (chapter 5). Main benefit is an application supporting team collaboration, which is used by students and teachers. The whole application is available on http://sourceforge.net/projects/kitscm/ under GPL license.
60

More than downloading : Visualization of data produced by sensors in a home environment

Bremstedt Pedersen, Ivan, Andersson, Alfred January 2012 (has links)
A home automation system usually contains a set of tools that users use to control devices in their homes, often remotely. These devices often include but are not limited to light switches, thermostats, thermometers, window blinds, and climate controls. The potential for these kinds of systems is huge because of the sheer number of devices that could be controlled and managed with minimal and inexpensive extra hardware. Many of the appliances in a normal home could benefit from being connected to a system that allows the owner to manage and control the devices in their home. Thus the number of potential devices is orders of magnitude larger than the number of homes connected to the system. There are several systems on the market that provide systems to monitor and control a home environment, however these systems only support specific in system devices. This uncovers a problem where a homeowner only has the opportunity to use specific products that fit into these systems. By introducing an open platform for the public that are not bound to any system we can allow more devices to be integrated in the home and contribute to further development of smarter homes. The goal with this project was to provide a scalable open platform with the possibility of asynchronous updating. This has been done by implementing multiple logical parts to both provide a web interface for the user and to allow us to handle communication and storage of data. All these parts are linked together to form a system of servers that handles all background operations. This thesis discusses and presents implementations of all of these servers, how they are implemented, communicate with each other, provide secure connections and how they can scale with increasing usage. In this process we also discuss and present techniques that were used, how to use them and their benefits, to help us reach our goal. / ”Home automation” syftar till ett system som låter användaren kontrollera och styra olika apparater i hemmet, ofta sker detta utifrån. Dessa apparater inkluderar, men är inte begränsade till ljusbrytare, termostater, termometrar, persienner eller klimatanläggningar. Potentialen för ett sådant system är enormt då antalet apparater som skulle kunna övervakas med endast minimal och billig extra hårdvara är stort. Många av dessa apparater kan dra nytta av att vara ansluten till ett system som gör det möjligt för ägaren att hantera och styra enheter i deras hem. Antalet apparater är därför mångdubbelt fler än antalet hem som är kopplade till systemet. Det finns flera system på marknaden som ger användaren ett sätt att övervaka och styra en hemmiljö, men dessa system är ofta låsta och stödjer bara specifika enheter. Genom att införa en öppen plattform för allmänheten som inte är bunden till något system, kan vi tillåta att fler enheter kan integreras i hemmet och bidra till ytterligare utveckling av smartare hem. Målet med detta projekt var att skapa en skalbar öppen plattform med möjlighet till asynkron uppdatering. Detta har gjorts genom att implementera flera logiska delar för att förse användaren med ett webbgränssnitt och för att tillåta oss hantera kommunikation och lagring av data. Alla dessa delar är sammanlänkade för att bilda ett system av servrar som hanterar alla bakgrundsprocesser. Denna avhandling diskuterar och presenterar implementeringar av alla dessa servrar, hur de genomförs, kommunicera med varandra, ger säkra anslutningar och hur de kan skala med ökad användning. I denna process diskuterar och presenterar vi de tekniker som använts, hur man använder dem och deras fördelar.

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