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1
Dippel, Markus. « Charakterisierung des Schmelzverhaltens selbstorganisierter Indium-Nanostrukturen auf WSe₂-Substraten / ». Konstanz, 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=96136629X.
Texte intégral
2
Maier, Andreas. « Strukturelle und magnetische Eigenschaften von CoPt 3-Nanostrukturen auf WSe 2 ». [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9683803.
Texte intégral
3
Trinh, Le-Huy. « Antennes reconfigurables pour les applications mobiles et réseaux sans fil ». Thesis, Nice, 2015. http://www.theses.fr/2015NICE4047/document.
Texte intégralRésumé :
Au cours de ces dernières années, les technologies de télécommunication ont fait d'énormes progrès, notamment dans les communications mobiles et les réseaux de capteurs sans fil (WSN). Pour répondre à l’augmentation de la capacité de transmission et à l’amélioration de la qualité des canaux de communications mobiles, l’élargissement de la bande de fonctionnement est nécessaire par l'utilisation d'antennes reconfigurables en fréquence. En outre, dans les applications WSN, afin de réduire les collisions, d’augmenter la distance de communication et d'optimiser la consommation, l’utilisation d’antennes reconfigurables en directivité est une bonne solution. Dans ce cadre, nos travaux de recherche ont portés sur la conception de différentes structures antennaires reconfigurables. Dans un premier temps nous avons réalisés une antenne reconfigurable à base de nouveaux éléments actifs, les digitally tunable capacitors (DTC). Ces composants sont de très bons candidats en vue d’une intégration d'antennes pour des applications communications mobiles et WSN. Ensuite nous nous sommes attachés à concevoir des structures multibande, MIMO et reconfigurables en fréquence, permettant d’augmenter la bande de fréquence de fonctionnement du système de communication, d'optimiser l'efficacité et la qualité spectrale et d'améliorer la qualité de canal. Enfin, une autre voie a été explorée, l’utilisation d’antennes reconfigurables en directivité pour des applications de WSN. Les résultats de simulation et de mesure sont également présentés dans ce chapitre. Grâce à l'utilisation de ce type de structures, la performance des WSN a été optimiséeIn recent years, telecommunication technologies have enormous progress, especially cellular communications and wireless sensor networks. To meet the demand of increasing transmission capacity, improving quality of cellular communication channels, expanding the operating band of the equipment is necessary. As passive antenna has reached the limit on increasing the operating band with the small size, the use of frequency reconfigurable antenna is a feasible solution. Besides, in the applications of WSN, to reduce collisions, increase communication distance and optimize consumption, directional reconfigurable antenna is a good proposal. In this thesis we present several reconfigurable antenna structures. Firstly, a new component is introduced; digitally tunable capacitor (DTC). Thanks to its advantages, such parts are good candidate to be integrated in the antenna for cellular communication and wireless sensor network applications. After, several antennas are introduced include multiband antenna, MIMO and frequency reconfigurable antenna, which can be used to extend the operating frequency band of the communication system, optimize spectral efficiency and quality improve channel quality. The structures of these antennas are introduced together with the results of simulation and measurement for the purpose of solving the challenges given in the future cellular communications systems. And then, the proposed approach to the design of reconfigurable directional antennas is presented. Several reconfigurable directional antennas, which are used in applications of WSN, are introduced. Thanks to the use of directional antennas reconfigurable, performance of WSN system will be optimized
4
Digiere, Adriano Ricardo [UNESP]. « Camada de gerenciamento para comunicação entre computadores baseada em redes sem fio (WSE-OS) ». Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/98660.
Texte intégralRésumé :
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O maior custo de propriedade de computadores não é o hardware ou o software, mas sim o tempo que os profissionais de informática gastam em suporte e manutenção dos ambientes computacionais. Em um conglomerado de computadores em rede, cada computador torna- se uma entidade gerenciada individualmente, o que gera contínuas solicitações de alterações de configuração, como instalação de atualizações de software, conexão e configuração de periféricos, criação de perfis de e-mail e aplicação de patches. Além disso, existe ainda o risco de furto de dados e invasão por hackers quando os computadores dos usuários não estão protegidos. Aliado a este cenário, a constante evolução dos sistemas computacionais e seu potencial de processamento, a cada dia são necessárias novas técnicas de aproveitamento destes recursos. Soluções que visam facilitar o gerenciamento de ambientes com grande massa de computadores de forma a tirar o máximo proveito do poder computacional concentrado em servidores já se tornaram necessidades reais, não só em grandes corporações, mas também em pequenas e médias empresas, além de outros tipos organizações, como por exemplo, instituições de ensino. Frente esta necessidade, focando uma ferramenta compatível neste cenário de crescimento, este trabalho apresenta um modelo de gerenciamento centralizado, nomeado WSE-OS (Wireless Sharing Environment – Operating Systems), baseado em técnicas de virtualização e acesso remoto seguro combinadas a um sistema de arquivos remotos em espaço de usuário. Esta solução elimina a necessidade da instalação e configuração de aplicativos “máquina a máquina”, além de tirar maior proveito do poder computacional existente nos servidores. A principal característica deste modelo que o destaca das soluções atuais é que ele é especificamente elaborado para operar sobre redes...
The largest cost of desktop ownership is not the hardware or software, but the time that administrators spend on support and maintenance of computing environments. In a conglomerate of computers in a network, each computer becomes an entity managed individually, which generates continuous requests for configuration changes, such as installing software updates, configuration and connection of peripherals, profiling email and applying patches. Moreover, there is the risk of data theft and hacking when users' computers are not protected. Allied to this scenario, the constant evolution of computer systems and their potential for processing, each day requires new techniques for exploitation of these resources. Solutions aimed facilitating the management of environments with large mass of computers to take maximum advantage of computing power concentrated on servers have become real needs, not only in large corporations but also small and medium enterprises, besides other types organizations, such as educational institutions. Facing this need, focusing on a tool that supported this growth scenario, this work presents a centralized management model, named WSE-OS (Wireless Sharing Environment – Operating Systems) based on virtualization techniques and secure remote access combined with a remote file system in user space. This solution eliminates the need for installing and configuring applications machine to machine, besides take greater advantage of existing computing power on the servers . The main feature of this model that highlights the current solutions is that it is specifically designed to operate on networks with low transmission rates, such as wireless networks. The WSE-OS is able to perform the replication of operating system images in an environment with WLAN communication, which makes management more flexible and independent of physical connections, besides offer... (Complete abstract click electronic access below)
5
Zhang, Rui. « Experimental and theoretical studies of electronic and mechanical properties of two-dimensional (2D) WSe₂ ». Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33228.
Texte intégralRésumé :
Two-dimensional (2D) transition metal dichalcogenides (TMDs) with intrinsic band gaps are considered to be prospective alternatives for graphene in the applications of emerging nano-semiconductor devices. As a significant member of the TMDs family, WSe₂ with superior optical properties attracts increasing attention, especially in the optoelectronics. In this thesis, the electronic and mechanical properties of 2D WSe₂ have been studied experimentally and theoretically. Firstly, the fabrication of substrate-supported and suspended pre-patterned WSe₂ FETs with the low-cost optical lithography and vapour HF etching technology have been realised. The subsequent electrical measurement of the fabricated WSe₂ FETs indicates that the WSe₂/dielectric interface can affect the electrical performance of 2D WSe₂ negatively. To gain more insights on the impact of field-effect on 2D WSe₂, first-principle calculations have been conducted in this research to study the evolutions of the crystal structure, electronic band structure, conductive channel size, and electrical transport property of WSe2 under various levels of field-effect. Furthermore, a layer thinning and chemical doping method of 2D WSe₂ by vapour XeF₂ exposure featured with good air-stability, scalability, and controllability has been developed to enable the layer engineering of 2D WSe₂ and integration of 2D WSe₂ to logic circuits, solar cells, and light-emitting diodes (LED). The thinning and doping mechanism has been investigated with a combination of Raman spectroscopy, photoluminescence (PL) spectroscopy, and Xray photoelectron spectroscopy (XPS) characterization techniques. Afterwards, the inplane elastic properties (including the Young's modulus, breaking strain, and etc.) of 2D WSe₂ have been measured with nanoindentation experiments implemented by atomic force microscopy (AFM). The results prove the suitability of 2D WSe₂ in the applications of flexible devices and nanoelectromechanical systems (NEMS) operating in the audio resonance frequency, such as acoustic sensors and loudspeakers. To provide a comprehensive understanding of the strain engineering of 2D WSe₂, the strain induced variations of the crystal structure, electronic band structure, and electrical transport property of 2D WSe₂ have been further studied with first-principle calculations, which paves the way for the performance tuning of 2D WSe₂ devices via strain and applications of 2D WSe₂ in strain sensors.
6
Digiere, Adriano Ricardo. « Camada de gerenciamento para comunicação entre computadores baseada em redes sem fio (WSE-OS) / ». São José do Rio Preto : [s.n.], 2011. http://hdl.handle.net/11449/98660.
Texte intégralRésumé :
Orientador: Roberta SpolonBanca: João Paulo Papa
Banca: Regina Helena Carlucci Santana
Resumo: O maior custo de propriedade de computadores não é o hardware ou o software, mas sim o tempo que os profissionais de informática gastam em suporte e manutenção dos ambientes computacionais. Em um conglomerado de computadores em rede, cada computador torna- se uma entidade gerenciada individualmente, o que gera contínuas solicitações de alterações de configuração, como instalação de atualizações de software, conexão e configuração de periféricos, criação de perfis de e-mail e aplicação de patches. Além disso, existe ainda o risco de furto de dados e invasão por hackers quando os computadores dos usuários não estão protegidos. Aliado a este cenário, a constante evolução dos sistemas computacionais e seu potencial de processamento, a cada dia são necessárias novas técnicas de aproveitamento destes recursos. Soluções que visam facilitar o gerenciamento de ambientes com grande massa de computadores de forma a tirar o máximo proveito do poder computacional concentrado em servidores já se tornaram necessidades reais, não só em grandes corporações, mas também em pequenas e médias empresas, além de outros tipos organizações, como por exemplo, instituições de ensino. Frente esta necessidade, focando uma ferramenta compatível neste cenário de crescimento, este trabalho apresenta um modelo de gerenciamento centralizado, nomeado WSE-OS (Wireless Sharing Environment - Operating Systems), baseado em técnicas de virtualização e acesso remoto seguro combinadas a um sistema de arquivos remotos em espaço de usuário. Esta solução elimina a necessidade da instalação e configuração de aplicativos "máquina a máquina", além de tirar maior proveito do poder computacional existente nos servidores. A principal característica deste modelo que o destaca das soluções atuais é que ele é especificamente elaborado para operar sobre redes... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The largest cost of desktop ownership is not the hardware or software, but the time that administrators spend on support and maintenance of computing environments. In a conglomerate of computers in a network, each computer becomes an entity managed individually, which generates continuous requests for configuration changes, such as installing software updates, configuration and connection of peripherals, profiling email and applying patches. Moreover, there is the risk of data theft and hacking when users' computers are not protected. Allied to this scenario, the constant evolution of computer systems and their potential for processing, each day requires new techniques for exploitation of these resources. Solutions aimed facilitating the management of environments with large mass of computers to take maximum advantage of computing power concentrated on servers have become real needs, not only in large corporations but also small and medium enterprises, besides other types organizations, such as educational institutions. Facing this need, focusing on a tool that supported this growth scenario, this work presents a centralized management model, named WSE-OS (Wireless Sharing Environment - Operating Systems) based on virtualization techniques and secure remote access combined with a remote file system in user space. This solution eliminates the need for installing and configuring applications "machine to machine", besides take greater advantage of existing computing power on the servers . The main feature of this model that highlights the current solutions is that it is specifically designed to operate on networks with low transmission rates, such as wireless networks. The WSE-OS is able to perform the replication of operating system images in an environment with WLAN communication, which makes management more flexible and independent of physical connections, besides offer... (Complete abstract click electronic access below)
Mestre
7
Crepaldi, Luis Gustavo [UNESP]. « Middleware de comunicação entre objetos distribuídos para gerenciamento de computadores baseado em redes sem fio (WSE-OS) ». Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/98663.
Texte intégralRésumé :
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Universidade Estadual Paulista (UNESP)
Para simplificar o gerenciamento de computadores, vários sistemas de administração estruturados por conexões físicas adotam técnicas avançadas para gestão de configuração de software. No entanto, a forte ligação entre hardware e o software faz com que haja uma individualização desta gerência, além da penalização da mobilidade e ubiqüidade do poder computacional. Neste cenário, cada computador torna-se uma entidade individual a ser gerenciada, exigindo operações manuais de configuração da imagem de sistema. Tecnologias que oferecem gestão centralizada baseadas em conexões físicas cliente-servidor, combinando técnicas de virtualização com a utilização de sistemas de arquivos distribuídos, refletem a degradação em flexibilidade e facilidade de instalação deste sistema gerenciador. Outras arquiteturas para gerenciamento centralizado que estruturam o compartilhamento de dados através de conexões físicas e dependem do protocolo PXE, apresentam os mesmos impasses descritos anteriormente. Diante das limitações dos modelos de gerenciamento centralizado baseado em conexões físicas, o objetivo deste trabalho é o desenvolvimento de um middleware de comunicação cliente-servidor como parte integrante e necessária para um ambiente de gerenciamento centralizado em redes de comunicações sem fio. Este ambiente, denominado WSE-OS (Wireless Sharing Enviroment ? Operating Systems), é um modelo baseado Virtual Desktop Infrastructure (VDI) que associa técnicas de virtualização e sistema de acesso remoto seguro para criação de uma arquitetura distribuída como base de um sistema de gestão. WSE-OS é capaz de realizar a replicação de sistemas operacionais em um ambiente de comunicação sem fio além de oferecer abstração de hardware aos clientes. O WSE-OS pode substituir o boot local com disco rígido por um boot de uma Imagem de Sistema Única...
To simplify computer management, various administration systems structured with physical connections adopt advanced techniques to manage software configuration. Nevertheless, the strong link between hardware and software makes for an individualism of that management, besides penalizing computational mobility and ubiquity. In this scenario, each computer becomes an individual entity to be managed, requiring manual operations of the system image configuration. Technologies that offer centralized management based on client-server physical connections, combining virtualization techniques with the use of distributed file systems in clusters with distributed processing on network computers reflect the deterioration in flexibility and ease of installation and maintenance of distributed applications. Other architectures for centralized management that structure the sharing of data through physical connections and depend on the PXE protocol, present the same dilemmas described above. Given the limitations models of centralized management based on physical connections, the objective of this project is the development of a middleware for client-server communication as part necessary of an environment for centralized management in wireless communications networks. This environment, called WSE-OS (Wireless Sharing Environment ? Operating Systems), is a model based Virtual Desktop Infrastructure (VDI), which combines virtualization techniques and secure access system for creating a distributed architecture as the basis for a management system. WSE-OS is capable of replicating operating systems in a wireless environment, addition to providing hardware abstraction to clients. The WSE-OS can replace the boot with local hard disk to a boot from SSI (Single System Image) virtualized in server via communication middleware, increasing flexibility and allowing multiple operating systems... (Complete abstract click electronic access below)
8
Crepaldi, Luis Gustavo. « Middleware de comunicação entre objetos distribuídos para gerenciamento de computadores baseado em redes sem fio (WSE-OS) / ». São José do Rio Preto : [s.n.], 2011. http://hdl.handle.net/11449/98663.
Texte intégralRésumé :
Resumo: Para simplificar o gerenciamento de computadores, vários sistemas de administração estruturados por conexões físicas adotam técnicas avançadas para gestão de configuração de software. No entanto, a forte ligação entre hardware e o software faz com que haja uma individualização desta gerência, além da penalização da mobilidade e ubiqüidade do poder computacional. Neste cenário, cada computador torna-se uma entidade individual a ser gerenciada, exigindo operações manuais de configuração da imagem de sistema. Tecnologias que oferecem gestão centralizada baseadas em conexões físicas cliente-servidor, combinando técnicas de virtualização com a utilização de sistemas de arquivos distribuídos, refletem a degradação em flexibilidade e facilidade de instalação deste sistema gerenciador. Outras arquiteturas para gerenciamento centralizado que estruturam o compartilhamento de dados através de conexões físicas e dependem do protocolo PXE, apresentam os mesmos impasses descritos anteriormente. Diante das limitações dos modelos de gerenciamento centralizado baseado em conexões físicas, o objetivo deste trabalho é o desenvolvimento de um middleware de comunicação cliente-servidor como parte integrante e necessária para um ambiente de gerenciamento centralizado em redes de comunicações sem fio. Este ambiente, denominado WSE-OS (Wireless Sharing Enviroment ? Operating Systems), é um modelo baseado Virtual Desktop Infrastructure (VDI) que associa técnicas de virtualização e sistema de acesso remoto seguro para criação de uma arquitetura distribuída como base de um sistema de gestão. WSE-OS é capaz de realizar a replicação de sistemas operacionais em um ambiente de comunicação sem fio além de oferecer abstração de hardware aos clientes. O WSE-OS pode substituir o boot local com disco rígido por um boot de uma Imagem de Sistema Única... (Resumo completo, clicar acesso eletrônico abaixo)Abstract: To simplify computer management, various administration systems structured with physical connections adopt advanced techniques to manage software configuration. Nevertheless, the strong link between hardware and software makes for an individualism of that management, besides penalizing computational mobility and ubiquity. In this scenario, each computer becomes an individual entity to be managed, requiring manual operations of the system image configuration. Technologies that offer centralized management based on client-server physical connections, combining virtualization techniques with the use of distributed file systems in clusters with distributed processing on network computers reflect the deterioration in flexibility and ease of installation and maintenance of distributed applications. Other architectures for centralized management that structure the sharing of data through physical connections and depend on the PXE protocol, present the same dilemmas described above. Given the limitations models of centralized management based on physical connections, the objective of this project is the development of a middleware for client-server communication as part necessary of an environment for centralized management in wireless communications networks. This environment, called WSE-OS (Wireless Sharing Environment ? Operating Systems), is a model based Virtual Desktop Infrastructure (VDI), which combines virtualization techniques and secure access system for creating a distributed architecture as the basis for a management system. WSE-OS is capable of replicating operating systems in a wireless environment, addition to providing hardware abstraction to clients. The WSE-OS can replace the boot with local hard disk to a boot from SSI (Single System Image) virtualized in server via communication middleware, increasing flexibility and allowing multiple operating systems... (Complete abstract click electronic access below)
Orientador: Marcos Antônio Cavenaghi
Coorientador: Roberta Spolon
Banca: João Paulo Papa
Banca: Regina Helena Carlucci Santana
Mestre
9
ESSAIDI, HATEM. « Contribution a l'obtention et a la caracterisation de couches minces de wse#2 pour applications au photovoltaique ». Nantes, 1995. http://www.theses.fr/1995NANT2055.
Texte intégralRésumé :
Suite aux travaux anterieurs realises au laboratoire sur les dichalcogenures de metaux refractaires, l'objet de ce travail a ete d'optimiser les procedes d'obtention de couches minces de wse#2, afin que leurs proprietes soient le plus proche possible de celles des monocristaux, de facon a pouvoir envisager leur utilisation dans le domaine photovoltaique. A cette fin deux techniques ont ete utilisees: la synthese simple a partir d'une couche mince de tungstene pulverise et d'un grain de selenium, le tout etant recuit dans un tube scelle sous vide. Si l'adherence des couches est fortement amelioree par rapport a celle des echantillons anterieurs grace a l'utilisation de tungstene pulverise, la reproductibilite reste cependant assez faible. La reaction a l'etat solide, induite thermiquement entre feuillets superposes de w et de se (w/se/w. . W/se), suivi d'un traitement thermique. Les couches obtenues sont stoechiometriques, cristallisees dans la structure 2h-wse#2 et texturees de tel facon que l'axe c des cristallites soit perpendiculaire au plan du substrat. Les mesures d'absorption optique montrent que la bande interdite est de l'ordre de celle mesuree dans les monocristaux (eg = 1,35ev). De plus les structures excitoniques (excitons a et b) sont parfaitement visibles sur le spectre d'absorption ce qui montre la bonne qualite des couches. Cependant si les couches ont des proprietes non reproductibles, leur resistivite, tres superieure a celle des monocristaux, reste controlee par les joints de grains. Afin de limiter cet effet, un traitement sous vapeur d'iode a ete mis au point, il permet de multiplier la conductivite par 10 au plus. Une premiere approche du comportement des couches minces de wse#2 dans une solution electrolytique a ete effectuee, on observe un effet photovoltaique
10
Treubel, Frank. « Wachstum, Struktur und Magnetismus von gamma-Mn auf Pt(111) und CoPt3̀(111) auf WSe 2(111) ». [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8885149.
Texte intégral
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Treubel, Frank. « Wachstum, Struktur und Magnetismus von gamma-Mn auf Pt(111) und CoPt 3(111) auf WSe 2(0001) / ». [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8875814.
Texte intégral
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Frey, Michael [Verfasser]. « WSE-Sensor zur Erkennung feuchter, nasser, schnee- und eisbedeckter Fahrbahnoberflächen : Beitrag zum Dynamischen Fahrbahn Informations System DFIS / Michael Frey ». Aachen : Shaker, 2005. http://d-nb.info/1181621186/34.
Texte intégral
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Yau, Louis. « Simulation analysis of learning and expectations in the stock exchange : a case study with the Warsaw Stock Exchange (WSE) ». Thesis, University of Leicester, 1996. http://hdl.handle.net/2381/35527.
Texte intégralRésumé :
Increasingly, it has become difficult to explain economic phenomena within the neo-classical framework in a period of changes when learning about the changes precedes any costly adaptation. The process of learning has been argued to be a missing element. It is defined as the continuous inference from observable data the unobservable state and structure of the market that are typically unknown. Learning is more detectable during rapid economic changes and when the gain- loss differential is critically enormous, like in the financial markets. Hence, an interactive learning model is formulated to study how learning and the interaction between market and traders can affect price. In particular, the noise trader approach which accounts for the excess volatility and the mean reversion phenomena in share prices, is used as a theoretical framework that allows learning to happen. A case study is done to four chosen shares in the Warsaw Stock Exchange (WSE), a newly-emerged market in a transitory economy. Analysis is done by means of simulation and detailed comparison between empirical and simulated data. The objectives are: (i) to understand the effect of learning and the interaction between market and agents and (ii) to search for the underlying conditions in the chosen markets so as to have a better understanding of them. The results suggest that the four chosen markets in WSE are not efficient. Self-fulfilling inefficient market beliefs of agents who are learning the state of the market with dynamically misspecified models may be a cause. Learning also leads to excess volatility and mean reversion in share prices. Moreover, free participation in the market can produce seemingly deceptive regression results against the objective process if agents are capable of influencing market realisation. This is best reflected in one of our controlled extreme cases with no learning in the market.
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Lima, Leonardo José de [UNESP]. « Proposta para aumento da escalabilidade do sistema WSE-OS por meio do escalonamento de conexões e gerenciamento da replicação de dados dos servidores ». Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/110380.
Texte intégralRésumé :
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Devido a queda gradual no custo de aquisição de novos computadores, há cada vez mais dispositivos computacionais adentrando o mercado. A grande quantidade de novos dispositivos gera heterogeneidade entre eles e esta dificulta a administração de ambientes computacionais, pois é necessário manter os sistemas funcionando em compatibilidade com dispositivos bastante distintos simultaneamente. O sistema WSE-OS propõe uma solução de centralização de dados e recursos que aborda o problema da heterogeneidade de maneira eficaz. Fazendo uso da tecnologia wireless a ferramenta WSE-OS utiliza uma estrutura Thin Client que permite aos seus clientes executarem instanciações de sistemas operacionais virtualizados armazenados no servidor. Este trabalho apresenta uma proposta que altera a estrutura do WSE-OS incluindo a capacidade de operar com múltiplos servidores, tendo como objetivo aumentar a escalabilidade, disponibilidade e confiabilidade da ferramenta por meio de técnicas de replicação do servidor e escalonamento das conexões. A replicação de dados consiste em detectar as alterações sofridas nos dados contidos em um determinado servidor e transmiti-las aos demais priorizando a consistência entre as réplicas. O escalonamento de conexões funciona ativamente distribuindo os clientes dentre os servidores para melhorar o desempenho da ferramenta
Due to a gradual decrease in the cost of purchasing new computers, there is more and more computing devices entering the market. The large quantity of new devices creates heterogeneity among them and this complicates the administration of computing environments, because is necessary to keep the systems running in compatibility with quite different devices simultaneously. The WSE-OS system proposes a solution for centralizing data and resources that addresses this problem effectively. Using wireless networking technology, the WSE-OS tool uses a Thin Client structure that allows its clients to execute instantiations of virtualized operating systems stored on the server. This paper presents a proposal that changes WSE-OS's structure including the ability to run with multiple servers, having as its goal increase scalability, availability and reliability through server’s data replication and staggering of connections. Data replication consists in detecting changes on data from a given server and transmit it to the others prioritizing the consistency among replicas. The staggering of connections works on actively distributing the clients among servers to improve system’s performance
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Lima, Leonardo José de. « Proposta para aumento da escalabilidade do sistema WSE-OS por meio do escalonamento de conexões e gerenciamento da replicação de dados dos servidores / ». São José do Rio Preto, 2013. http://hdl.handle.net/11449/110380.
Texte intégralRésumé :
Orientador: Roberta SpolonBanca: José Remo Ferreira Brega
Banca: Sarita Mazzini Bruschi
Resumo: Devido a queda gradual no custo de aquisição de novos computadores, há cada vez mais dispositivos computacionais adentrando o mercado. A grande quantidade de novos dispositivos gera heterogeneidade entre eles e esta dificulta a administração de ambientes computacionais, pois é necessário manter os sistemas funcionando em compatibilidade com dispositivos bastante distintos simultaneamente. O sistema WSE-OS propõe uma solução de centralização de dados e recursos que aborda o problema da heterogeneidade de maneira eficaz. Fazendo uso da tecnologia wireless a ferramenta WSE-OS utiliza uma estrutura Thin Client que permite aos seus clientes executarem instanciações de sistemas operacionais virtualizados armazenados no servidor. Este trabalho apresenta uma proposta que altera a estrutura do WSE-OS incluindo a capacidade de operar com múltiplos servidores, tendo como objetivo aumentar a escalabilidade, disponibilidade e confiabilidade da ferramenta por meio de técnicas de replicação do servidor e escalonamento das conexões. A replicação de dados consiste em detectar as alterações sofridas nos dados contidos em um determinado servidor e transmiti-las aos demais priorizando a consistência entre as réplicas. O escalonamento de conexões funciona ativamente distribuindo os clientes dentre os servidores para melhorar o desempenho da ferramenta
Abstract: Due to a gradual decrease in the cost of purchasing new computers, there is more and more computing devices entering the market. The large quantity of new devices creates heterogeneity among them and this complicates the administration of computing environments, because is necessary to keep the systems running in compatibility with quite different devices simultaneously. The WSE-OS system proposes a solution for centralizing data and resources that addresses this problem effectively. Using wireless networking technology, the WSE-OS tool uses a Thin Client structure that allows its clients to execute instantiations of virtualized operating systems stored on the server. This paper presents a proposal that changes WSE-OS's structure including the ability to run with multiple servers, having as its goal increase scalability, availability and reliability through server's data replication and staggering of connections. Data replication consists in detecting changes on data from a given server and transmit it to the others prioritizing the consistency among replicas. The staggering of connections works on actively distributing the clients among servers to improve system's performance
Mestre
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BENHIDA, SAMIR. « Mise au point de techniques d'obtention de couches minces de wse#2 et de cuinse#2, caracterisation en vue d'applications dans le domaine photovoltaique ». Nantes, 1992. http://www.theses.fr/1992NANT2043.
Texte intégralRésumé :
Les dichalcogenures de metaux refractaires sont des composes dont les proprietes chimiques et photoelectriques sont susceptibles d'applications dans le domaine de la conversion d'energie photoelectrochimique. Le wse#2, de part la valeur de sa bande interdite (1. 35 ev) est l'un des plus prometteurs de ces composes. L'objet de ce travail a ete de mettre au point des techniques d'obtention de ce materiau. A cette fin les montages de depot utilises ont ete optimises de facon a obtenir les couches desirees. Celles-ci ont ete caracterisees par diffraction de rayons x, microscopie a balayage et a transmission, microsonde-electronique, spectroscopie de photoelectrons (xps), absorption optique et mesure de la variation de la conductivite en fonction de la temperature. Dans le cas de couches minces de wse#2, ce compose a pu etre obtenu par simple synthese a partir d'une plaque de tungstene et d'un grain de selenium, le tout etant recuit dans un tube scelle sous vide. Cependant l'adherence des couches au substrat de tungstene est faible. C'est pourquoi une autre technique a ete utilisee a savoir, depot de feuillet superpose w/se/w. . . W suivi d'un traitement thermique, qui permet, par reaction chimique a l'etat solide, la formation de couches minces de wse#2. Les conditions du traitement thermique ont ete optimisees de facon a obtenir des couches continues et texturees de telle maniere que l'axe c des cristallites soit perpendiculaire au plan du substrat. Les mesures de conductivite montrent cependant que celle-ci est controlee par les joints de grains. Ceci est confirme par la microscopie electronique a transmission qui montre que la continuite entre les cristallites orientes et assuree par des microcristallites desordonnes. Parallelement a l'etude du wse#2, des couches de cuinse#2 ont ete realisees de facon a generaliser la technique d'obtention mise au point pour le wse#2. Les feuillets de cu, in, se sont evapores sequentiellement dans le rapport stchiometrique desire. Un recuit a 623k pendant 3h permet d'obtenir du cuinse#2 cristallise dans la structure chalcopyrite. Le contact mo/cuinse#2, souvent utilise dans les structures a base de cuinse#2 a ete etudie en tracant des profils xps. On montre que se diffuse dans mo avec formation de mose#2 a l'interface
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Mahmoudi, Aymen. « Propriétés électroniques des dichalcogénures bi-dimensionnels de métaux de transition ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP106.
Texte intégralRésumé :
Le sujet de cette thèse s'inscrit dans la thématique des matériaux bidimensionnels (2D) d'épaisseur atomique. L'étude des propriétés optiques et électroniques des hétérostructures hybrides à base de dichalcogénures de métaux de transition (TMD) MX₂ (M = Mo, W ; X = S, Se, Te) est aujourd'hui considérée avec attention en raison de futures applications et d'études plus fondamentales. Plus que leurs propriétés physiques intrinsèques, en configuration multicouche, ces matériaux offrent des phénomènes physiques prometteurs tels que la modulation de la valeur de la bande interdite, la ferroélectricité pour des configurations cristallines spécifiques, etc. En particulier, ce travail se consacre aux hétérostructures hybrides à base de diséléniure de tungstène (WSe₂) sur des substrats de graphène et de phosphate de gallium (GaP). En mettant en œuvre des techniques de microscopie et de spectroscopie telles que la spectroscopie Raman et la spectroscopie de photoémission résolue en angle (ARPES), une étude des propriétés électroniques, optiques et structurelles d'hétérostructures composées de plusieurs matériaux 2D a été réalisée afin de fournir une meilleure compréhension de ces systèmes émergents. Par conséquent, les premières mesures directes de la structure de bande électronique de la phase rhomboédrique de la structure bicouche de WSe₂ déposée sur un substrat 2D de graphène sont présentées dans ce manuscrit. La croissance directe de ce matériau 2D sur un substrat 3D de GaP a été étudiée pour plusieurs épaisseurs. Ces travaux ont permis d'identifier l'effet de la nature de la phase cristalline ainsi que la méthode de croissance sur les structures de bandes électroniques, ce qui permet une meilleure compréhension de ces systèmes émergentsThe subject of this thesis is two-dimensional (2D) materials of atomic thickness. The study of the optical and electronic properties of hybrid heterostructures based on MX₂ transition metal dichalcogenides (TMDs) (M = Mo, W; X = S, Se, Te) is now being carefully considered with a view to future applications and more fundamental studies. Beyond their intrinsic physical properties, in multilayer configurations, these materials offer promising physical phenomena such as modulation of bandgap values, ferroelectricity for specific crystal configurations, and so on. In particular, this work focuses on hybrid heterostructures based on tungsten diselenide (WSe₂) on graphene and gallium phosphate (GaP) substrates. Using microscopy and spectroscopy techniques such as Raman spectroscopy and angle-resolved photoemission spectroscopy (ARPES), we investigated the electronic, optical, and structural properties of heterostructures composed of several 2D materials to better understand these emerging systems. Accordingly, the first direct measurements of the electronic band structure of the rhombohedral phase of the WSe₂ bilayer structure deposited on a 2D graphene substrate are presented in this manuscript. The direct growth of this 2D material on a 3D GaP substrate has been studied for several thicknesses. This work has enabled us to identify the effect of the nature of the crystalline phase and the growth method on the electronic band structures, providing a better understanding of these emerging systems
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Zhang, Nan. « Propriétés électroniques de MoS2 / MoSe2van der Waals heterostructures ». Thesis, Toulouse, INSA, 2020. http://www.theses.fr/2020ISAT0017.
Texte intégralRésumé :
Le sujet de ma thèse concerne l’étude des propriétés optiques fon-damentales des dichalcogénures des métaux de transition (DCMT)des couches ultra-mince et plus précisément les hétérostuctures con-stituées de matériaux MX2(où M est du molybdène (Mo) et X dusoufre (S) ou du sélénium (Se)), liées entre elles par des interactionsde type Van der Waals. Le premier chapitre de la thèse a été con-sacré pour la description des propriétés fondamentales générales des(DCMT) exfolié et amincie jusqu’une monocouche. Egalement, leshétérostuctures à base des DCMT ont été largement décrites.Le chapitre 2 décrit les techniques expérimentales mises à dispo-sition pour servir mon projet de recherche soit en terme de mesuresou en terme de préparation des échantillons.Dans le chapitre 3, je présente l’effet de la photo-génération surles propriétés des exciton émis inter-couche. La photo-générationétant identifié à partir une augmentation de l’énergie de dissociationdes trions (via luminescence) accompagnée par un changement carac-téristique du rapport d’intensité de photoluminescence d’exciton etde trion dans le MoS2. Simultanément, j’ai observé une diminutionde l’intensité de PL de l’exciton généré inter-couche. Par contre lesignal PL composé des excitons et trions dans la couche de MoSe2aété amélioré montrant que le transfert de charges inter-couche peutêtre contrôlé en contrôlant le niveau de dopage. Cet effet observéest persistant sur une échelle de temps de plusieurs heures, tant quel’échantillon est maintenu sous vide. Ceci indique un mécanisme im-pliquant la désorption, induite par un laser, des molécules physisor-bées à la surface de l’hétérostructure. Je soutiens cette hypothèse endévoilant la sensibilité du taux de photo-génération sur la longueurd’onde d’excitation. Le processus de photo- génération se produitbeaucoup plus rapidement pour les photons ayant une énergie plusélevée.Dans le chapitre 4, je présente le résultat de l’impact du motifmoiré sur le spectre d’exciton inter-couche dans l’hétérostructureMoS2/ MoSe2. La formation du motif moiré est un phénomène car-actéristique des empilements de van der Waals où, en raison de lafaible interaction entre les couches chacune conservent ses propresparamètres de réseau. Par conséquent, en raison d’un petit anglede torsion ou d’une discordance de réseau entre les monocouches, unpotentiel variable dans l’espace périodique peut être induit. Ce po-tentiel peut avoir un impact non trivial sur les propriétés optiques desexcitons intra et inter-couche des hétérostructures de dichalcogénurede métaux de transition. Ici, je montre des preuves expérimentalesde l’impact du motif de moiré sur l’émission intra-couche dans unehétérostructure de MoSe2/ MoS2encapsulée avec du nitrure de borehexagonal (h-BN). Le potentiel périodique dans le plan se traduit par une clivage de spectre d’émission et ou d’absorption de l’excitonet du trion dans la couche de MoSe2. La différence d’énergie ob-servée entre les pics clivés est tout à fait conforme aux prévisionsthéoriques. De plus, ce chapitre contient une description détailléede la manière dont l’orientation relative des flocons dans une tellehétérostructure peut être révélée par la spectroscopie de générationdu deuxième harmonique.Le chapitre 5 contient les résultats des études préliminaires surl’impact de la qualité des échantillons et la possibilité de générerune polarisation de vallée via l’application d’un champ magnétique.Dans ces études, trois types de structures sont comparés, à savoirle MoSe2préparé par CVD et le MoSe2encapsulé par h-BN, ainsique l’hétérostructure MoSe2 / MoS2. De plus, j’ai trouvé que laformation d’un motif moiré a un impact négligeable sur le facteur gde Landé sur la transition excitonique intra-layerIn my thesis, I concluded results of my three years investigation of the optical properties of MoSe2/MoS2 transition metal dichalcogenides heterostructures. Thesis starts with the general overview of the properties of transition metal dichalcogenides monolayers and their heterostucers. This is followed by the detailed description experimental techniques which wear used to characterize photoresponse of heterostructures and their preparation. Next three paragraphs are devoted to the rustles of my investigations:In chapter 3 the impact of characteristic for transition metal dichalcogenides effect photodoping on the interlayer exciton emission properties is presented. The photodoping isidentified by the increasing (upon illumination) trion dissociation energy, accompanied by a characteristic change of the exciton/trion photoluminescence intensity ratioin MoSe2. At the same time, I observe decreasing photoluminescence intensity of the interlayer exciton. In the same time the combined PL intensity of the exciton and the trion in MoSe2 is enhanced, showing that the interlayer charge transfer can be controlled by the doping level. This observed effect is persistent on a timescale of several hours, as long as the sample is maintained under vacuum. This indicate a mechanism involving laser induced desorption of molecules physisorbed on the surface of the heterostructure. I support this hypothesis by revealed sensitivity of the photodoping rate on the excitation wavelength. The process of photodoping occurs much faster for higher energy photons.In chapter 4 I present result of the impact of moiré pattern on the intralayer exciton spectrum in MoS2/MoSe2 heterostructure. The moiré pattern formation is a phenomenon characteristic for van der Waals stacks where due to the weak interlayer interaction the ingredient layers preserve their own lattice parameters. Therefore due to small twist angle or of lattice mismatch between the monolayers periodic spatially varying potential is induced. This potential can have nontrivial impact on the optical properties of both intra- and interlayer excitons of transition metal dichalcogenide heterostructures. Here, I show experimental evidences of the moiré pattern impact on intralayer emission in a MoSe2/MoS2 heterobilayer encapsulated in hexagonal boron nitride. The periodic in-plane potential results in a splitting of the MoSe2 exciton and trion in emission and (for the exciton) absorption spectra. The observed energy difference between the split peaks is fully consistent with theoretical predictions. Moreover this chapter contain detailed description how the relative orientation of the flakes in such heterostructure can be revealed by second harmonic generation spectroscopy.Chapter 5 contains result of the initial studies about the impact of sample quality and possibility to generate valley polarization by the magnetic field. In this studies three type of structures are compared namely CVD grown and h-BN encapsulated MoSe2, together with MoSe2/MoS2 heterostructure. In addition I found that the formation of moire pattern has negligible impact on the Lande g-factor on intralayer excitonic transition
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Oskarsson, Lina. « Regnvatteninsamling : Vattenbesparingspotential i svenska förhållanden med fallstudie i Järlåsa ». Thesis, Uppsala universitet, Luft-, vatten- och landskapslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-417853.
Texte intégralRésumé :
Vattenbesparing och alternativa lösningar för att tillgodose vattenbehovet har blivit mer aktuellt de senaste åren med torka. Regnvatteninsamling för hushållsanvändning används redan på många platser runtom i världen men är begränsad i Sverige idag. Syftet är att dels undersöka en lämplig dimensionering av ett system för regnvatteninsamling för hushåll i Jälåsa och att identifiera olika drivkrafter och hinder. Metoden i denna studie har varit dels massbalans- och effektivitetsberäkningar för att se hur mycket regnvatten som kan samlas in och dels intervjuer med två teknikleverantörer och fem kommuner för att utvärdera den juridiska, sociala och ekonomiska potentialen. Resultatet visade att tankstorlek på mellan 1000 och 4000 liter är rimligt för hushållsanvändning till toalett eller toalett och tvättmaskin och ger en effektivitet (procent av vattenbehovet som täcks av regnvatten) på mellan 83,6 % och 96,0 %. Vilken storlek som är mest lämplig beror på faktorer såsom vad regnvattnet används till, takyta, antal personer i hushållet och om first-flushbortledning används. Beräkningar visar att ungefär 19-29 % av den totala dricksvattenförbrukningen skulle kunna sparas i Järlåsa, vilket motsvarar ungefär 4 400 till 6 700 kubikmeter dricksvatten per år. Resultatet visar även att torrperioder då tanken är tom blir kortare med en större tankstorlek och det finns tydliga skillnader i volym vatten i tanken mellan olika nederbördsrika år. Enligt kommuner ansågs potentialen för regnvatteninsamling vara störst för bevattning i dagsläget men att de även var positivt inställda till annan användning såsom toalettspolning och tvättmaskin. Identifierade hinder var oro kring kontamination av dricksvatten, brist på ekonomisk lönsamhet till följd av låga dricksvattenpriser i Sverige och behov av förtydligande av krav och vilka risker som finns med regnvatteninsamling. Idag är potentialen och motivationen som störst för de som har dålig tillgång på vatten och en ökad miljömässig medvetenhet skulle kunna öka implementeringen av regnvatteninsamling i Sverige. Slutsatsen är att det finns potential för regnvatteninsamling men att det fortfarande krävs viss utveckling och mer kunskap om regnvatteninsamling under svenska förhållanden.Water saving and alternative solutions to supply drinking water have become more important due to several consecutive droughts in recent years in Sweden. Rainwater harvesting for households is already being used in many places around the world but still has limited application in Sweden. The purpose with this study is to investigate a suitable sizing of a rainwater harvesting system in Järlåsa and to identify drivers and obstacles for implementation. The methods used in this study were firstly calculations based on mass balance and efficiency estimates and secondly interviews with two technology providers and five municipalities. The results showed that a tank size between 1000 and 4000 liters would be suitable for the purpose of supplying water for flushing toilets and for washing machines and the efficiency (percentage of water demand being met by rainwater) would be between 83,6% and 96,0%. What size tank is recommended depends on factors such as what rainwater is used for, roof area, number of people in household and whether first-flush is diverted. Results show that around 19-29%, around 4 400 to 6 700 cubic meters per year, of the total potable water consumption could be saved in Järlåsa every year using rainwater harvesting. The results also show that the dry periods, when the tank was empty, become shorter with a larger tank size and that there are distinct differences in the volume rainwater in the tank between years with varying precipitation. According to municipalities the potential was highest for irrigation purposes today but there was also potential for use in household for flushing toilets and supplying washing machines. The identified obstacles were concern regarding contamination of the drinking water supply, lack of economic profitability as a consequence of low water prices and the need for clarification of requirements and risks with rainwater harvesting. Today the potential and motivation is highest for those with an insufficient water supply and an increase in the environmental awareness could possibly enhance implementation further. The conclusion is that there is potential for rainwater harvesting but that there still is a need for some development and more knowledge regarding rainwater harvesting under Swedish conditions.
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Zielinski, Kamil. « Langfristige Renditeentwicklung nach Börseneinführungen und Kapitalerhöhungen am polnischen Kapitalmarkt ». Doctoral thesis, Humboldt-Universität zu Berlin, Wirtschaftswissenschaftliche Fakultät, 2013. http://dx.doi.org/10.18452/16837.
Texte intégralRésumé :
Die vorliegende Studie entstand, um die langfristige Renditeentwicklung polnischer Aktien nach Börseneinführungen und Kapitalerhöhungen in den Jahren 1994-2008 zu untersuchen. Ein besonderes Augenmerk richtet sich dabei auf die Erkennung und Analyse der performancerelevanten Unternehmenseigenschaften sowie auf die Erklärung der festgestellten Marktanomalien mit Hilfe ausgewählter Modellansätze. Die empirischen Analysen wurden aus dem Blickwinkel eines Kleininvestors durchgeführt, wodurch die meisten Ergebnisse, neben dem wissenschaftlichen Wert, eine hohe Praxisrelevanz besitzen. Die Untersuchung von insgesamt 263 Börseneinführungen ergab, dass die Emissionsrenditen der meisten Aktien zwar signifikant positiv waren, längerfristig bauten sie sich aber ab. Am Ende des 36-sten Notierungsmonats wiesen sie insgesamt eine starke Underperformance auf. Dabei entwickelten sich die langfristigen marktbereinigten IPO-Renditen in den 90-er Jahren wesentlich schlechter, als nach der Jahrhundertwende. Die Analyse des Kursverhaltens nach 157 Kapitalerhöhungen durch Aktien- und Bezugsrechtsemissionen zeigte, dass innerhalb der dreijährigen Halteperiode die Performance der betrachteten Stichprobe von der Rendite des Gesamtmarktes nur geringfügig abweichte. Dabei entwickelten sich die Kurse von Aktien der kleineren Firmen wesentlich schlechter, als die Aktienkurse der hochkapitalisierten Unternehmen.This study investigates the long-term stock return after initial public offerings and seasoned equity offerings occurred between 1994 and 2008. A particular attention is being paid to the identification and analysis of performance-relevant issuing firm characteristics and the explanation of the identified market anomalies by means of the preselected explanatory models. Since the empirical study was carried out from the small investor’s perspective, the majority of the obtained results provide not only a considerable scientific value, but also a strong relevance to the actual practice. The study examined 263 IPOs of common stocks and found an overwhelmingly positive initial return. However, this return vanished gradually on the long run, resulting in a high overall underperformance in 36 months after the first listing. In this respect, it is remarkable that the long-term returns of the IPO-stocks issued in the 1990s proved considerably lower than of those placed after 2000. The examination of the long-term stock price behaviour after 157 SEOs reveals only a tiny difference between the performance of the sample and the overall market return. Noteworthy is however the fact that equity issues conducted by smaller firms led usually to significantly poorer stock performance, than when equity was offered by large capitalized companies.
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Niste, Vlad. « WS2 nanoparticles as lubricant additives ». Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/383967/.
Texte intégralRésumé :
Due to their excellent tribological properties and potential to replace problematic lubricant additives currently in use, WS2 nanoparticles (NPs) have spurred considerable interest from academia and industry over the last two decades to decipher their mechanism of action. To elucidate the mechanism, this study carried out tribological tests at high pressures and low/high temperatures (40 and 100ºC) and investigated the tribofilm generated on the wear track and its wear and friction properties. It was found that WS2 NPs react with the metal substrate at high temperatures to form a chemical tribofilm covered with squashed NPs. The generation of this tribofilm accounts for their excellent tribological properties. By investigating the chemical and mechanical properties of the tribofilm, it was possible to explain the tribological properties of WS2 NPs. Based on chemical analysis results, a layered structure was proposed for the chemically formed tribofilms. The large amount of tungsten compounds in the composition may explain the excellent mechanical properties of the tribofilm, as revealed by nanoindentation tests. The importance of base oil polarity was investigated. It was found that the efficiency of the NPs is reduced in polar oils, because the oil molecules can compete with the nanoadditive by adsorbing on the metal surface in the tribological contact and impeding the formation of the tribofilm. To investigate which type of WS2 NPs (2H or IF) performs better in tribological applications and if other tungsten dichalcogenides (IF-WSe2) are also potential candidates as nanoadditives, tribological tests and analysis of the wear tracks were performed. 2H-WS2 showed superior friction and wear reducing properties in high-pressure high-temperature contacts. The tribological performance of 2H-WS2 NPs was compared to that of popular conventional additives, e.g. antiwear zinc dialkyldithiophosphates (ZDDPs) and organic friction modifiers (OFMs). At the end of three hour tests, 2H-WS2 NPs and ZDDP+OFM mixtures showed similar antiwear properties, but 2H-WS2 NPs induced a significant reduction of the friction coefficient in the mixed and boundary lubrication regimes. The ability of 2H-WS2 NPs to inhibit hydrogen permeation in high strength bearing steel used in fuel cells and wind turbines was also investigated. Thermal desorption spectroscopy revealed that the chemical tribofilm generated on the wear tracks can significantly reduce the concentration of hydrogen and water in the steel substrate after rolling contact fatigue tests performed in high-temperature high-pressure conditions.
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Schwartz, Kerry, Candice Rupprecht, Mary Ann Stoll, Holly Thomas-Hillburn, Tasha Krecek-Lynch, Alex Prescott et Sushmita Ramaswamy. « Water Scene Investigation (WSI) Program ». College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2013. http://hdl.handle.net/10150/298147.
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Krajíček, Tomáš. « Analýza multicastových protokolů pro WSN ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219337.
Texte intégralRésumé :
This work deals with the issue of multicast traffic over ZigBee wireless network and implementation of corresponding protocols in to MATLAB background, further with realisation of multicast data transmission, consequential energy performance evaluation and comparation of particular protocols.
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Takahshi, Naoko. « Flagella synthesis in Rhodobacter sphaeroides WS8 ». Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259820.
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Brás, Luís Pedro Marques. « Sectorial antennas for WSN localization system ». Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/12857.
Texte intégralRésumé :
Doutoramento em Engenharia EletrotécnicaThis work investigates low cost localization systems (LS) based on received signal strength (RSS) and integrated with different types of antennas with main emphasis on sectorial antennas. The last few years have witnessed an outstanding growth in wireless sensor networks (WSN). Among its various possible applications, the localization field became a major area of research. The localization techniques based on RSS are characterized by simplicity and low cost of integration. The integration of LS based on RSS and sectorial antennas (SA) was proven to provide an effective solution for reducing the number of required nodes of the networks and allows the combination of several techniques, such as RSS and angle of arrival (AoA). This PhD thesis focuses on studying techniques, antennas and protocols that best meet the needs of each LS with main focus on low cost systems based on RSS and AoA. Firstly there are studied localization techniques and system that best suit the requirements of the user and the antennas that are most appropriate according to the nature of the signal. In this step it is intended to provide a fundamental understanding of the undertaken work. Then the developed antennas are presented according to the following categories: sectorial and microstrip antennas. Two sectorial antennas are presented: a narrowband antenna operating at 2.4 to 2.5 GHz and a broadband antenna operating at 800MHz-2.4GHz. The low cost printed antennas were designed to operate at 5 GHz, which may be used for vehicular communication. After presenting the various antennas, several prototypes of indoor/outdoor LS are implemented and analyzed. Localization protocols are also proposed, one based on simplicity and low power, and the other on interoperability with different types of antennas and system requirements.
O presente trabalho investiga sistemas de localização (SL) de baixo custo baseados na intensidade do sinal (RSS) e integrados com diferentes tipos de antenas com principal destaque para antenas sectoriais. Os últimos anos testemunharam um crescimento surpreendente de redes de sensores sem fios (RSSF), onde entre diversas aplicações possíveis, a localização tornou-se uma das principais áreas de pesquisa. Técnicas baseadas na intensidade do sinal caracterizam-se pela simplicidade e baixo custo de integração. A integração de SL baseados na intensidade do sinal recebido e antenas sectoriais (AS) oferecem uma solução eficaz para reduzir o número de nós necessários e para combinar diversas técnicas de localização. Esta tese de doutoramento foca-se no estudado de técnicas, antenas e protocolos de acordo com os requisitos de cada sistema localização com especial atenção para sistemas de baixo custo baseados na intensidade do sinal e no ângulo de chegada. Inicialmente são estudadas técnicas e SL de acordo com as necessidades do utilizador e as antenas que melhor se enquadram de acordo com a natureza do sinal. Esta etapa tem como objectivo proporcionar a compreensão fundamental do trabalho desenvolvido. Em seguida são apresentadas as antenas desenvolvidas divididas em: antenas sectorias e antenas impressas de baixo custo. Duas antenas sectoriais são apresentadas: uma de banda estreita a operar a 2,4-2,5GHz e outro de banda larga 800MHz-2.4GHz. As antenas impressas foram desenvolvidas para operar a 5 GHz, pelo que podem ser utilizadas para comunicação veicular. Após apresentação das diversas antenas vários protótipos de SL interiores/exteriores são implementados e analisados. Protocolos de localização são também propostos, um baseado na simplicidade e baixo consumo, outro na interoperabilidade com diferentes tipos de antenas e requisitos do sistema.
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Bendeck, Fawsy. « WSM-P workflow semantic matching platform ». München Verl. Dr. Hut, 2008. http://d-nb.info/99216298X/04.
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Bejoy, B. J., et B. Paramasivan. « RELIABILITY ORIENTED TRANSPORT PROTOCOL IN WSN ». IJCSN Journal, 2012. http://hdl.handle.net/10150/229012.
Texte intégralRésumé :
Wireless Sensor Network consists of tens or thousands of
sensor nodes scattered in a physical space and one or
more Base stations or Sinks. Even thought developed for
military applications now they find a wide variety of
civilian applications also. Some of the applications are
Target tracking, Animal monitoring, Vehicle monitoring.
The need (or lack thereof) for reliability in a sensor
network is firmly dependent upon the specific
application the sensor network is used for. Some
applications like re-tasking or reprogramming sensor
nodes [upgrading software or algorithms, adding codes,
scripts etc] over -the-air requires assured delivery of
high-priority events to sinks. We believe that as the
number of sensor network applications grows, there will
be a need to build more powerful general-purpose
hardware and software environments capable of
reprogramming or retasking sensors to.Wireless sensor network is a special form of wireless networks dedicated to surveillance and monitoring applications Reliability in wireless sensor network is application specific. The specific form of reliability might change from application to application. Our idea is to generate reliability based transport protocol that is customizable to meet the needs of emerging reliable data applications in sensor networks and is also adaptive when the nodes are mobile. In our approach, clusters are formed for minimizing energy dissipation. The nodes maintain a neighbor list to forward data and any changes in the local topology can trigger updates to a node’s neighbor list. If a node notices that its neighbor list has changed, it can spontaneously re-advertise all of its data thus providing reliable transport in mobility conditions also. Our approach has five phases-setup, relaying, relay initiated error recovery, selective status reporting and node supervising. Our simulation results prove that the proposed approach can outperform existing related techniques and is highly responsive to the various error and mobility conditions experienced in sensor networks.
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Zafar, Muhammad Asif, et Zeshan Aslam Khan. « Fire Detection in Coal Mines Using WSN ». Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-5030.
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Fire Detection in Coal Mines Using WSN is an application for monitoring and detection of fire in coal mines using wireless sensor networks. The application uses BDI (Belief, Desire and Intention) based multi agent model and its implementation on sensor networks. The Language which is interpreted by Jason is an extension of AgentSpeak; this is based on the BDI Architecture. The BDI agents are reactive planning systems, systems that are not meant to compute the value of a function and terminate, but rather designed to be permanently running, reacting to some form of event. The distributed model of environment is adopted to overcome the communication overhead, power consumption, network delay and reliability on a centralized base station.
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Wang, Teng. « Water Quality Monitoring System based on WSN ». Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107735.
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With the growth of economy in recent years, the water quality monitoring becomes a critical issue about water pollution. Water Quality Monitoring has a big influence on the aquaculture management, waste water treatment, drinking water and some other applications. There is a trend to build a wireless sensor network system for water quality monitoring. This system detects pH, conductivity, dissolved oxygen, turbidity, temperature, ORP (Oxidation-Reduction Potential), BOD (Biochemical Oxygen Demand), Flow and etc. Some important electrochemical parameters of water quality should also be detected, like Ca2+, Mg2+, Cl2, Cl-, NO3-, NH3+, CO2/CO32-, F-, BF4-, K+, Na+. The water quality monitoring system should guarantee the accuracy, security and reliability. In this paper, I research an integrated system model for water quality monitoring system which is based on chlorine analyzer, turbidity meter, pH meter, conductivity meter, dissolved oxygen meter and so on. I analyze the water quality monitoring program according to different physical environment.
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Sha, Mao Xuan, Xi Tao Wang et Shu Zuo. « WSN Setup by means of Software Agents ». Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-16450.
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A significant challenge in the Wireless Sensor Networks (WSN) research field is to find flexible and energy efficient strategies to perform the network setup and configuration to accomplish specified sensing missions. This thesis presents an approach which uses mobile agents to disseminate and allocate sensing missions to the sensor nodes. The addressed problem refers to the selection of appropriate nodes to perform the sensing mission, by using a decentralized approach supported by mobile software agents. Traditional approaches to deal with WSN setup use the pre-planned strategies, which are deliberately modelled, designed and tuned before the network deployment, and thus are not flexible. This thesis presents an alternative approach based on Belief Desire Intention-model agents using JASON, instead of traditional approaches. Simulation results provides evidences that this approach can achieve the goals of a sensing mission setup by decisions autonomously taken by the sensor node, diminishing then the need for communication among the sensor nodes, hence saving energy resources.
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Hassmund, David. « WSC Wind Science Centre : Centret för vindenergi ». Thesis, Mittuniversitetet, Avdelningen för industridesign, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-20246.
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Målet med projektet har varit att designa en byggnad där information om vindkraft kan presenteras. Utgångspunkten iprojektet har varit upplevelsen med ett antal studier som grund. Området som berörs är Borgsjö som är optimalt läge fördenna typ av informationsbyggnad. Genom studiebesök, enkätundersökning, intervjuer och analys har ett antal konceptframställts. För att engagera besökarna så har även en enhet för utomhusbruk tagits fram där användaren med sin egenstyrka kan generera elektricitet och jämföra med miniverket. Slutkonceptet är en sluten byggnad med en interaktiv projektionoch statisk informatoin med interaktiva möjligheter på motsatt sida. Pekskärmar visade dig vara ett föredraget interaktionsmediumtillsammans med projektorn, alternativet pekskärm har dock valts bort i slutkonceptet till fördel för denstatiska lösningen.
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Koh, Kenneth Johannesen. « Analysis of Key Industrial WSN MAC Protocols ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for telematikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-27346.
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This paper looks at two MAC protocols for wireless sensor networksfor use in industrial applications developed at the Ubicom Lab, at theUniversity of Ulsan. A theoretical comparison of the MAC protocolsare performed to understand more about the benefits and downsidesto both of them, and experimental scenarios to validate the theoreticalanalysis are suggested. Theoretical analysis suggests that BigMAC hasan advantage in environments with high interference and frequent linkbreaks, while I-MAC has an advantage when the network topology isstable.
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AUZA, JOSE MAURICIO NAVA. « PERFORMANCE OF ENERGY EFFICIENT ALGORITHMS IN WSN ». PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35321@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
As redes de sensores sem fio se constituem numa área que outorga grandes oportunidades para a oferta de uma série de aplicações inovadoras e com baixo custo. Os dispositivos destas redes são bastantes pequenos e sua fonte de alimentação são baterias. O tempo de vida destas é limitado, limitando assim o tempo da vida dos sensores e da rede como um todo. Por esta razão nos últimos anos o tema de eficiência energética tem atraído grande interesse de pesquisadores. O aumento do custo da energia e do consumo global da energia pelo setor de ICT (Information and Communications Technologies) têm crescido vertiginosamente devido ao aumento continuo do número de clientes e da demanda por aplicações de maior complexidade. Por tudo isso têm sido desenvolvidos distintos métodos e técnicas para economizar energia nas RSSF. Neste trabalho se implementam dois algoritmos que levam em conta critérios para economizar os custos de energia da rede e através de experimentos de simulação se avalia os mesmos. Nos resultados pode se observar as vantagens de trabalhar com sistemas que visam a eficiência energética.
The WSNs (Wireless Sensor Networks) belong to an area that gives rise to great opportunities to spread innovative and low cost applications. These kinds of networks are composed of tiny devices with limited energy. The main source of power supply for WSNs are batteries, which are limited in cycle life, thus limiting the sensors lifetime and the network as a whole. Due to that fact, the energy efficiency network is becoming the main concern to be addressed by researchers. Rising energy prices and global energy consumption by the ICT (Information and Communications Technologies) sector have grown dramatically due to the continuous increase in customer number and the demand for more complex applications. For the reasons outlined above, different energy-saving techniques for WSNs have been developed. Two energy-saving algorithms for WSNs were implemented in this thesis, and they were tested by experimental evaluation using simulation. The results obtained from the simulations showed the advantages of working with systems aiming at energy efficiency.
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Elliott, Bradley Jay. « Optimization of WSU Total Ankle Replacement Systems ». Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1341333609.
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Toldov, Viktor. « Adaptive MAC layer for interference limited WSN ». Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10002/document.
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A l'époque de l'Internet des Objets, le nombre de dispositifs communicants ne cesse d'augmenter. Souvent, les objets connectés utilisent des bandes de fréquences « industriel, scientifique et médical (ISM) » pour effectuer les communications. Ces bandes sont disponibles sans licence, ce qui facilite le déploiement de nouveaux objets connectés. Cependant, cela mène aussi au fait que le niveau d'interférences augmente dans les bandes ISM. Les interférences ont non seulement un impact négatif sur la qualité de service, mais aussi elles causent des pertes de messages couteuses en énergie, ce qui est particulièrement nocif pour les nœuds capteurs souvent limités en énergie. Dans cette thèse, l'impact des interférences sur la consommation énergétique des nœuds est étudié expérimentalement. Les résultats de ces expérimentations sont utilisés pour estimer la durée de vie des nœuds en fonction de différents niveaux d’interférence subis. Puis, un algorithme de Radio Cognitive (RC) basé sur la technique d’ échantillonnage de Thompson est proposé et évalué par la simulation et implémentation. Les résultats montrent que l'approche proposée trouve le meilleur canal plus vite que les autres techniques. De plus, une extension multi sauts pour RC est proposée et évaluée par expérimentation lors d'une compétition EWSN Dependability Competition. Finalement, le protocole adaptatif WildMAC est proposé pour le cas d'usage du projet LIRIMA PREDNET qui consiste à surveiller des animaux sauvages. Les performances sont évaluées par simulation avec le simulateur WSNet. Les résultats montrent que la solution proposée respecte les contraintes imposées par le projet PREDNET dans la zone cibléeIn the era of the Internet of Things, the number of connected devices is growing dramatically. Often, connected objects use Industrial, Scientific and Medical radio bands for communication. These kinds of bands are available without license, which facilitates development and implementation of new connected objects. However, it also leads to an increased level of interference in these bands. Interference not only negatively affects the Quality of Service, but also causes energy losses, which is especially unfavorable for the energy constrained Wireless Sensor Networks (WSN). In the present thesis the impact of the interference on the energy consumption of the WSN nodes is studied experimentally. The experimental results were used to estimate the lifetime of WSN nodes under conditions of different levels of interference. Then, a Thompson sampling based Cognitive Radio (CR) adaptive solution is proposed and evaluated via both, simulation and hardware implementation. Results show that this approach finds the best channel quicker than other state of the art solutions. An extension for multihop WSN was proposed for this CR solution and evaluated by hardware implementation in the framework of EWSN Dependability Competition. Finally, an adaptive WildMAC MAC layer protocol is proposed for the usecase of the LIRIMA PREDNET wildlife animal tracking project. Obtained field range test data were used to theoretically estimate cell densities and deployment zone coverage in this Low Power Widea Area Network (LPWAN). Then performance of the protocol was evaluated in WSNet simulation. The results show performance that allows to respect PREDNET project requirements with the given coverage
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Michopoulos, Vasilis. « Congestion and medium access control in 6LoWPAN WSN ». Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/11463.
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In computer networks, congestion is a condition in which one or more egressinterfaces are offered more packets than are forwarded at any given instant [1]. In wireless sensor networks, congestion can cause a number of problems including packet loss, lower throughput and poor energy efficiency. These problems can potentially result in a reduced deployment lifetime and underperforming applications. Moreover, idle radio listening is a major source of energy consumption therefore low-power wireless devices must keep their radio transceivers off to maximise their battery lifetime. In order to minimise energy consumption and thus maximise the lifetime of wireless sensor networks, the research community has made significant efforts towards power saving medium access control protocols with Radio Duty Cycling. However, careful study of previous work reveals that radio duty cycle schemes are often neglected during the design and evaluation of congestion control algorithms. This thesis argues that the presence (or lack) of radio duty cycle can drastically influence the performance of congestion control mechanisms. To investigate if previous findings regarding congestion control are still applicable in IPv6 over low power wireless personal area and duty cycling networks; some of the most commonly used congestion detection algorithms are evaluated through simulations. The research aims to develop duty cycle aware congestion control schemes for IPv6 over low power wireless personal area networks. The proposed schemes must be able to maximise the networks goodput, while minimising packet loss, energy consumption and packet delay. Two congestion control schemes, namely DCCC6 (Duty Cycle-Aware Congestion Control for 6LoWPAN Networks) and CADC (Congestion Aware Duty Cycle MAC) are proposed to realise this claim. DCCC6 performs congestion detection based on a dynamic buffer. When congestion occurs, parent nodes will inform the nodes contributing to congestion and rates will be readjusted based on a new rate adaptation scheme aiming for local fairness. The child notification procedure is decided by DCCC6 and will be different when the network is duty cycling. When the network is duty cycling the child notification will be made through unicast frames. On the contrary broadcast frames will be used for congestion notification when the network is not duty cycling. Simulation and test-bed experiments have shown that DCCC6 achieved higher goodput and lower packet loss than previous works. Moreover, simulations show that DCCC6 maintained low energy consumption, with average delay times while it achieved a high degree of fairness. CADC, uses a new mechanism for duty cycle adaptation that reacts quickly to changing traffic loads and patterns. CADC is the first dynamic duty cycle pro- tocol implemented in Contiki Operating system (OS) as well as one of the first schemes designed based on the arbitrary traffic characteristics of IPv6 wireless sensor networks. Furthermore, CADC is designed as a stand alone medium access control scheme and thus it can easily be transfered to any wireless sensor network architecture. Additionally, CADC does not require any time synchronisation algorithms to operate at the nodes and does not use any additional packets for the exchange of information between the nodes (For example no overhead). In this research, 10000 simulation experiments and 700 test-bed experiments have been conducted for the evaluation of CADC. These experiments demonstrate that CADC can successfully adapt its cycle based on traffic patterns in every traffic scenario. Moreover, CADC consistently achieved the lowest energy consumption, very low packet delay times and packet loss, while its goodput performance was better than other dynamic duty cycle protocols and similar to the highest goodput observed among static duty cycle configurations.
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Firouzbakhsh, Navid, et Karchegani Arash Mokhtari. « Internet to WSN configuration and access using 6LoWPAN ». Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-26607.
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The Internet of Things mission is to connect any objects to the Internet, in order to provide the ability to access everything, everywhere. It will enable people to control and monitor their environment in a very convenient way. In order to fulfill the Internet of Things mission, one idea is to wrap a non-IP based protocol stack in the objects equipped with sensors, actuators and computing resources to enable them to be connected to the Internet through a protocol translation gateway. An alternative and competing idea, is to embed the TCP/IP stack into such smart objects, enabling them to interact with the Internet seamlessly. However, in order to satisfy the Internet of Things needs such as scalability, interoperability and simplicity of configuration and management, the use of IP architecture for smart objects is of interest, since it has proven itself a highly scalable, interoperable and simple communication technology. In particular, the new optimized Internet Protocol, IPv6, which is capable of providing any single object with a unique address, accompanied by many other great features such as plug-and-play and a real end-to-end connectivity, can offer great benefits to the Internet of Things. Nevertheless, most of the smart objects specially deployed in Wireless Sensor Networks a subset of Internet of Things, are not able to adapt the large IPv6 packet because of their Link- Layer limitations. Hence, it is a quite challenging task for these devices to transmit an IPv6 packet. For this reason, the Internet Engineering Task Force organization has offered an IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN) solution in order to solve the IPv6 adaptability problem. This thesis presents the design and deployment of an IPv6-based WSN using this solution. The result of this work is building a 6LoWPAN based on the Contiki OS. This WSN is able to send the measured environment temperature to a web server and control the status of a light through the Internet in a standard, scalable, and seamless way.
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Dong, Ni. « Building control and automation via PID and WSN ». Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199344.
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Li, Zhitan. « The Optimization of Solar Energy Harvesting in WSN ». Thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-35560.
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In recent year, wireless sensor networks have gradually become an indispensable part of people's daily lives. Energy consumption and energy harvesting play an important role in these systems. In outdoor, there is no doubt that solar energy is more suitable to powering the wireless sensor nodes. Although the energy consumption of these systems has been greatly reduced and the lifetime of sensor nodes also be improved through the larger capacity of supercapacitor or larger size of solar panel. But it will generate another kind of squander, how to choose a suitable solar panel and supercapacitor is appearance in our view. In this paper, I optimized the solar energy harvesting system from two aspects of capacity of supercapacitor and size of solar panel. The objective of this thesis has shown that as small solar panel and supercapacitor as possible for a given load of these systems under low consumption condition. Here, I establish the simulation in Simulink of Matlab, and build a low-power consumption; high-security solar energy harvesting hardware system for monitoring environment in Sundsvall, Sweden. Through the comparison between the simulation and real monitor to verify the feasibility
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Goulart, Rodrigo Rafael Vilarreal. « Um modelo híbrido para o WSD em biomedicina ». Pontifícia Universidade Católica do Rio Grande do Sul, 2013. http://hdl.handle.net/10923/1628.
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Previous issue date: 2013This work studies Word Sense Disambiguation (WSD) in the Biomedicine domain for English language, using external knowledge sources. Among the existing proposals for the selection of a sense for an ambiguous word, there is the graph-based approach. This approach uses a metric in the evaluation of graphs containing candidates to the correct sense for the ambiguous word. In this research, a set of metrics is analyzed individually, and, based on this evaluation, we propose a hybrid model for the selection of the metrics in order to determine the most adequate metric to be employed. The model makes use of a set of features and heuristics that determine a semi-supervised solution for WSD. The results obtained with experiments show an improvement in performance and reveal new perspectives of research. The proposed model raises the hit rate to 68,48%, increasing significantly in 3,52% the rate reported in literature.
Este trabalho estuda o Word Sense Disambiguation no domínio da Biomedicina, para a língua inglesa, com uso de fontes externas de conhecimento. Dentre as propostas existentes para a seleção de um sentido para uma palavra ambígua, está a abordagem baseadas em grafos. Essa abordagem emprega uma métrica na avaliação de grafos que contêm candidatos ao sentido correto da palavra ambígua. Nesta pesquisa um conjunto de métricas é analisado individualmente e, com base nas avaliações, propõe-se um modelo híbrido de seleção de métricas com o objetivo de determinar a métrica mais adequada a ser empregada. O modelo faz uso de um conjunto de features e heurísticas que determinam uma solução semi-supervisionada para o WSD. Os resultados obtidos com experimentos apontam melhoria na performance e revelam novas perspectivas de pesquisa. O modelo proposto eleva a taxa de acerto a 68,48%, aumentando significativamente em 3,52% a taxa reportada na literatura.
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Peng, Tingqing. « WSN Routing Schedule Based on Energy-aware Adaptation ». Thesis, Mittuniversitetet, Institutionen för informationssystem och –teknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-39223.
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In view of the problem of uneven load distribution and energy consumption among nodes in a multi-hop wireless sensor network, this research constructs the routing schedule problem as a MOP (Multi-objective Optimization Problem), and proposed an energy-aware routing optimization scheme RDSEGA based on multi-objective optimization. In this scheme, in order to avoid the searching space explosion problem caused by the increase of nodes, KSP Yen's algorithm was applied to prune the searching space, and the candidate paths selected after pruning are recoded based on priority. Then adopted the improved strengthen elitist genetic algorithm to get the entire network routing optimization scheme with the best energy efficiency. At the same time, in view of the problem of routing discontinuity in the process of path crossover and mutation, new crossover and mutation method was proposed that based on the gene fragments connected by the adjacent node or the same node to maximize the effectiveness of the evolution result. The experimental results prove that the scheme reduced the energy consumption of nodes in the network, the load between nodes becomes more balanced, and the working time of the network has been prolonged nearly 40% after the optimization. This brings convenience to practical applications, especially for those that are inconvenient to replace nodes.
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Li, Jiakai. « AI-WSN : Adaptive and Intelligent Wireless Sensor Networks ». University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1341258416.
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Karlsson, Tom, et Mike Persson. « Outdoor localization in long range WSN using trilateration ». Thesis, Linköpings universitet, Fysik och elektroteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-141689.
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This thesis report investigates how good position estimations that can be done outdoors with received signal strength indication (RSSI) trilateration for sub 1-GHz radio nodes. A custom network and an empirical distance model have been created as well as a technique for weighting multiple distance estimations, using wrapped normal probability density functions. The developed localization system was tested on an open area of one square kilometer, to estimate a node’s position on various locations. To evaluate the localization system, mean and median error of the estimated positions were calculated.
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Votava, Martin. « Lokalizační protokol pro WSN s podporou mobility uzlů ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218265.
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Work is focused on wireless sensor networks.The main theme is the mobility and localization in these networks. This work describes different methods and capabilities of mobile and localization schemes. This work describes a new localization protocol for wireless sensor networks. Finally, there is included a new protocol in the simulation at Network Simulator 2 and evaluate the results obtained.
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Ceriotti, Matteo. « Guaranteeing Communication Quality in Real World WSN Deployments ». Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/369149.
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Networks of smart interconnected objects have allowed the integration of the artificial world into the physical one. The interaction over a wireless medium is simultaneously the technology enabler and the primary hindering factor. The complexity and variability of the behavior of low power wireless communication is one of the challenges making the design and deployment of a system based on this technology a unique and demanding experience. In this thesis, we describe the deployment of two operational systems for structural health monitoring and adaptive lighting, undertaken by our research group. Our major contribution, among others, covers the definition and implementation of the system services enabling the monitoring infrastructure to guarantee the required quality. The resulting unique design and reliability provide concrete support to the vision of wireless sensor networks as dependable monitoring infrastructure.
Despite the success in meeting the user needs, the simple yet effective solutions exploited in the aforementioned deployments make apparent the limitations of the widely used approaches to coordinate access to the communication medium. This thesis also argues that the currently employed solutions at the MAC layer are insufficient to provide guarantees to the resource user. Therefore, we introduce Reins-MAC, a Time-Division Multiple-Access (TDMA) communication scheduler that coordinates access to the medium in a fully decentralized fashion. Limited flexibility, scalability, robustness, as well as increased overhead and complexity are commonly recognized shortcomings of TDMA approaches. Reins-MAC overcomes these limitations by adapting the scheduling to match local availability and natural connectivity variations. Moreover, each node is empowered with full control over its own communication resources.
The ability to anarchically apply changes to the communication schedule allows the steering of the resource allocation towards individual needs, dictated by the higher layers in the network stack. The resulting quality and anarchy in accessing the communication resource affect the design and implementation of WSNs, opening new horizons where the application regains control of the primary resource: communication.
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Ceriotti, Matteo. « Guaranteeing Communication Quality in Real World WSN Deployments ». Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/563/1/thesis.pdf.
Texte intégralRésumé :
Networks of smart interconnected objects have allowed the integration of the artificial world into the physical one. The interaction over a wireless medium is simultaneously the technology enabler and the primary hindering factor. The complexity and variability of the behavior of low power wireless communication is one of the challenges making the design and deployment of a system based on this technology a unique and demanding experience. In this thesis, we describe the deployment of two operational systems for structural health monitoring and adaptive lighting, undertaken by our research group. Our major contribution, among others, covers the definition and implementation of the system services enabling the monitoring infrastructure to guarantee the required quality. The resulting unique design and reliability provide concrete support to the vision of wireless sensor networks as dependable monitoring infrastructure.
Despite the success in meeting the user needs, the simple yet effective solutions exploited in the aforementioned deployments make apparent the limitations of the widely used approaches to coordinate access to the communication medium. This thesis also argues that the currently employed solutions at the MAC layer are insufficient to provide guarantees to the resource user. Therefore, we introduce Reins-MAC, a Time-Division Multiple-Access (TDMA) communication scheduler that coordinates access to the medium in a fully decentralized fashion. Limited flexibility, scalability, robustness, as well as increased overhead and complexity are commonly recognized shortcomings of TDMA approaches. Reins-MAC overcomes these limitations by adapting the scheduling to match local availability and natural connectivity variations. Moreover, each node is empowered with full control over its own communication resources.
The ability to anarchically apply changes to the communication schedule allows the steering of the resource allocation towards individual needs, dictated by the higher layers in the network stack. The resulting quality and anarchy in accessing the communication resource affect the design and implementation of WSNs, opening new horizons where the application regains control of the primary resource: communication.
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Yaoming, Chen. « A smart gateway design for WSN health care system ». Thesis, Jönköping University, JTH. Research area Robust Embedded Systems, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-11826.
Texte intégralRésumé :
Using Wireless Sensor Networks (WSNs) in health care system has yielded a tremendous effort in recent years. However, in most of these researches tasks like sensor data processing, health states decision making and emergency messages sending are done by a remote server. Numbers of patient with large scale of sensor data consume a lot of communication resource, bring a burden to the remote server and delay the decision time and notification time. In this paper, we present a prototype of a smart gateway that we have implemented. This gateway is an interconnection and services management platform especially for WSN health care systems at home environments, by building a bridge between WSN and public communication networks, compatible with an on-board data decision system (DDS) and a lightweight database, which enable to make the patient’s health states decision in the gateway in order to get faster response time to the emergencies. We have also designed the communication protocols between WSN, gateway and remote servers. Additionally Ethernet, Wi-Fi and GSM/GPRS communication module are integrated into the smart gateway in order to report and notify information to care-givers. We have conducted experiments on the proposed smart gateway by performing it together with a wireless home e-health care sensor network. The results show that it is reliable and has low latency and low power consumption.
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Gao, Jie. « Intelligent and Interactive Package Based on RFID and WSN ». Licentiate thesis, KTH, Elektroniksystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-49765.
Texte intégralRésumé :
An intelligent and interactive package can interact with people smartly, safely and friendly. It involves many technologies such as electronics, optics, biologic, magnetics and electro-mechanics. By combined with Radio Frequency Identification (RFID) and Wireless Sensor Network (WSN), intelligent and interactive packaging technology has been an emerging and global research topic over the years. In this thesis, a new technology, named Controlled Delamination Material (CDM), is introduced. It was primarily used in aerospace applications in the past and further developed by Stora Enso AB. A CDM product can delaminate easily in a controlled way by the use of electrical current. This concept opens up many interesting application possibilities for the traditional packaging industry. In order to understand the delamination mechanism, some related work on the electrochemical characteristics of the material showed the possibility to facilitate the interactive packaging system design. A paper-based package which is integrated with RFID system and CDM is presented to realize an intelligent and interactive system. It can be opened automatically through a finger touch. The opening action is controlled electrically by RFID system. The test results of the demonstration have proved feasibility of the solution and shown the potential for mass production. Following this solution, an interactive pharmaceutical package for pervasive healthcare is proposed by using EPCglobal Gen2 RFID technology. A Gen2 RFID system significantly increases the efficiency of information exchange, and reduces the medication error rate and the possibility of sale counterfeit drugs. It makes the medication accessible for patient only at the prescribed dose and time, and at the same time, the information for the action of taking medication will be delivered to the doctor as well. Such interactive pharmaceutical package not only gives unprecedented high patient compliance, but also improves the communication between patients and healthcare staffs. By integrating WSN with various bio-chemical sensors, in addition to temperature and moisture sensors, more kinds of information can be involved in the intelligent and interactive packaging communication system. It enhances the functionalities of the package such as rotecting the integrity and effectiveness of product, providing safety information details, and being child resistance, senior friendlinessQC 20111205
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Lagana, Marcello. « Cognitive WSN access based on local WLAN traffic estimation ». Thesis, KTH, Kommunikationsnät, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91890.
Texte intégralRésumé :
The recent growth in the deployment of wireless networks that access the unlicensed ISM bands has introduced the issue of co-existence between different kinds of wireless technologies. In this work we address the enhancement of the performance of the low-cost Wireless Sensor Network nodes competing for spectrum access with the WLAN devices, that are more powerful in terms of transmission and computational power. Those low-cost WSN nodes are usually battery powered devices with low computational capabilities and limited battery capacity, thus the traditional methods for accessing the wireless spectrum should be revised, including throughput and energy efficiency optimization while considering the hardware constraints of the nodes. In this work we provide tools for spectrum activity prediction that will be used by a WSN cognitive MAC to minimize the collision probability with WLAN transmissions, hence the number of retransmissions, increasing consequently the energy efficiency of communication. We propose two approaches for WLAN spectrum activity modeling considering different probability distributions for the idle WLAN spectrum periods. The first considers the universal activity of the WLAN, while the second takes into account the hardware limitations of the sensors in terms of the detection range. For both modeling options we provide low-complexity algorithms based on either numerical estimation methods or neural networks for the parameter estimation that are suitable for the employment in the WSN. We complete the work with an extensive performance analysis in terms of estimation accuracy and we show that, even with a spatial limitedknowledge of the WLAN traffic, the sensors could derive a good approximation of the universal activity model.
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Mir-Shekari, Sarah Yasamin. « Glycosylation of the influenza A/WSN/33 virus haemagglutinin ». Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294355.
Texte intégral