• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 285
  • 88
  • 46
  • 37
  • 27
  • 13
  • 4
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 592
  • 592
  • 470
  • 104
  • 87
  • 82
  • 81
  • 81
  • 79
  • 64
  • 63
  • 61
  • 55
  • 49
  • 49
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Anchor Nodes Placement for Effective Passive Localization

Pasupathy, Karthikeyan 08 1900 (has links)
Wireless sensor networks are composed of sensor nodes, which can monitor an environment and observe events of interest. These networks are applied in various fields including but not limited to environmental, industrial and habitat monitoring. In many applications, the exact location of the sensor nodes is unknown after deployment. Localization is a process used to find sensor node's positional coordinates, which is vital information. The localization is generally assisted by anchor nodes that are also sensor nodes but with known locations. Anchor nodes generally are expensive and need to be optimally placed for effective localization. Passive localization is one of the localization techniques where the sensor nodes silently listen to the global events like thunder sounds, seismic waves, lighting, etc. According to previous studies, the ideal location to place anchor nodes was on the perimeter of the sensor network. This may not be the case in passive localization, since the function of anchor nodes here is different than the anchor nodes used in other localization systems. I do extensive studies on positioning anchor nodes for effective localization. Several simulations are run in dense and sparse networks for proper positioning of anchor nodes. I show that, for effective passive localization, the optimal placement of the anchor nodes is at the center of the network in such a way that no three anchor nodes share linearity. The more the non-linearity, the better the localization. The localization for our network design proves better when I place anchor nodes at right angles.
142

Uticaj bežične senzorske tehnologije na upravljanje montažnim sistemima / Impact of wireless sensor technology on control of assembly systems

Gogolak Laslo 26 June 2014 (has links)
<p>U doktorskoj disertaciji obrađen je problem upravljanja montažnim<br />sistemima pomoću bežične senzorske tehnologije u cilju poboljšanja<br />efikasnosti proizvodnje i poboljšanja kvaliteta proizvoda. U okviru<br />ove disertacije je razvijen model bežičnog upravljačkog sistema za<br />upravljanje i nadzor industrijskih procesa. Glavni cilj istraživanja<br />je razvoj integrisanog sistema za praćenje pozicije radnog predmeta i<br />praćenje okolnosti u kojima se radni predmet nalazi u montažnim<br />sistemima. Rezultati istraživanja su potvrđeni eksperimentalnim<br />istraživanjem u laboratorijskoj i u realnoj industrijskoj sredini.</p> / <p>The dissertation deals with the problem of monitoring and controlling<br />industrial assembly lines by wireless sensor technology with the aim of<br />improving the efficiency of production and the quality of the product. A model<br />of a wireless controlling system has been developed for monitoring and<br />controlling industrial processes. The main focus of the study is the<br />development of an integrated system for monitoring the position of the<br />product and the influences on the product in the assembly lines. The results<br />are confirmed by experiments in a laboratory and real industrial environment.</p>
143

Custom biomedical sensors for application in wireless body area networks and medical device integration frameworks

Li, Kejia January 1900 (has links)
Doctor of Philosophy / Department of Electrical & Computer Engineering / Steve Warren / The U.S. health care system is one of the most advanced and costly systems in the world. The health services supply/demand gap is being enlarged by the aging population coupled with shortages in the traditional health care workforce and new information technology workers. This will not change if the current medical system adheres to the traditional hospital-centered model. One promising solution is to incorporate patient-centered, point-of-care test systems that promote proactive and preventive care by utilizing technology advancements in sensors, devices, communication standards, engineering systems, and information infrastructures. Biomedical devices optimized for home and mobile health care environments will drive this transition. This dissertation documents research and development focused on biomedical device design for this purpose (including a wearable wireless pulse oximeter, motion sensor, and two-thumb electrocardiograph) and, more importantly, their interactions with other medical components, their supporting information infrastructures, and processing tools that illustrate the effectiveness of their data. The GumPack concept and prototype introduced in Chapter 2 addresses these aspects, as it is a sensor-laden device, a host for a local body area network (BAN), a portal to external integration frameworks, and a data processing platform. GumPack sensor-component design (Chapters 3 and 4) is oriented toward surface applications (e.g., touch and measure), an everyday-carry form factor, and reconfigurability. Onboard tagging technology (Chapters 5 and 6) enhances sensor functionality by providing, e.g., a signal quality index and confidence coefficient for itself and/or next-tier medical components (e.g., a hub). Sensor interaction and integration work includes applications based on the GumPack design (Chapters 7 through 9) and the Medical Device Coordination Framework (Chapters 10 through 12). A high-resolution, wireless BAN is presented in Chapter 8, followed by a new physiological use case for pulse wave velocity estimation in Chapter 9. The collaborative MDCF work is transitioned to a web-based Hospital Information Integration System (Chapter 11) by employing database, AJAX, and Java Servlet technology. Given the preceding sensor designs and the availability of information infrastructures like the MDCF, medical platform-oriented devices (Chapter 12) could be an innovative and efficient way to design medical devices for hospital and home health care applications.
144

VHF & UHF energy harvesting radio system physical and MAC layer considerations / VHF and UHF energy harvesting radio system physical and MAC layer considerations

Zhang, Xiaohu January 1900 (has links)
Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn / Wireless Sensor Network industrial and civilian applications have been moved closer to us since they were originally developed for defense applications. They have been or will be widely used in industrial process monitoring and control, earth quake monitoring, healthcare applications, construction health monitoring, home automation, traffic control, and space exploration. The IEEE802.15.4 standard defines the PHY and MAC layers for low power wireless sensor networks. However, applications and research of wireless sensor networking are centered on battery powered devices. To remove the battery from the system is the ultimate goal of this research by using Energy Harvesting technology, which will largely reduce the wireless sensor network maintenance cost, increase the option open to application environments and push the speed of wireless sensor network industrialization. This thesis tackles the problem of RF link budget and PHY layer design for Energy Harvesting Wireless Sensor Network Nodes, through a modification to PHY/MAC layers. To this end, a prototype of energy harvesting radio is developed that hinges on burst-communication and solar cell energy harvesting techniques. The choice of operating frequency is considered relative to transmission range, antenna technology and RF link budget, and quantified by propagation measurements at four unlicensed frequencies in the VHF through UHF spectrums. A short preamble, PHY payload protocol frame structure and synchronization method are also proposed in order to support long sleep period duty cycle necessary in Energy Harvesting Radio systems. Some related work has recently begun under a standardization effort known as 802.15.4f. It is hoped that this thesis will contribute to this effort.
145

Redes de sensores sem fio na coleta de dados fisiológicos de bovinos para aplicações na zootecnia de precisão / Wireless sensor networks technology applied to bovine physiological data acquisition for precision animal production

Arce, Aldo Ivan Céspedes 22 February 2008 (has links)
Este trabalho mostra a aplicação das redes de sensores sem fio na monitoração de variáveis fisiológicas de bovinos. A necessidade de experimentar técnicas de coleta de dados, que causem menos perturbações no comportamento natural dos animais de interesse da zootecnia de precisão, foi a principal motivação deste trabalho. Para testar a aplicabilidade da tecnologia das redes de sensores sem fio neste campo, foi desenvolvida uma infra-estrutura, utilizando técnicas de instrumentação eletrônica e comunicação sem fio via rádio-freqüência. A rede foi projetada com o protocolo floating base sensor network (FBSN) que implementa uma topologia adhoc com escolha aleatória dos nós. Os protótipos desenvolvidos foram utilizados para efetuar coletas de sinais cerebrais e temperaturas corporais de bovinos adultos. Foram desenvolvidos também os softwares embarcados e de supervisão e um simulador de deslocamento bovino, que foi utilizado como ferramenta de auxílio no projeto da infra-estrutura de monitoramento implementada. O consumo das fontes de energia e a relação custo-beneficio do sistema foram os principais itens avaliados. Os resultados obtidos mostraram que é possível utilizar redes de sensores sem fio como técnicas eficientes para coleta de dados fisiológicos de bovinos. / This work presents an application of wireless sensor networks technology used for bovine physiological variables monitoring. The main stimulus of this work was the precision animal production researcher\'s interest in developing and testing new techniques that could allow data acquisition with less interference in animal behavior. In order to test the feasibility of the wireless sensor network technology in this area, an infrastructure was developed using electronic instrumentation and radio frequency wireless communication techniques. The network was projected to support the floating base sensor network protocol that is a special kind of adhoc topology with randomic selection of path nodes. The developed prototypes were used to acquire brain electrical activity and body temperature from bovines. The development of supervisor and embedded software and a bovine\'s displacement simulator tool was also described here. The energy consumption and the cost-benefit relationship of the network nodes were the main evaluated features. The results obtained prove that the wireless sensor networks can be considered as an efficient technique to be used to acquire bovine\'s physiological data.
146

Sensoriamento automático e participativo em cidades. / Automatic and participatory sensing in cities.

Silva, Ademir Ferreira da 18 January 2016 (has links)
As cidades estão a seu tempo e a seu modo, modernizando os serviços prestados à população. Entre os diversos fatores que estão contribuindo para esta evolução estão a diversificação e proliferação de sensores, nos diversos domínios de serviços das cidades, e os novos canais de comunicação com os munícipes, entre eles, as redes sociais e mais recentemente os sistemas crowdsensing, motivados pelos anseios sociais, por melhores serviços públicos e pela popularização dos dispositivos móveis. Nesta direção, a eficiência administrativa é um fator essencial, uma vez que as cidades estão se mostrando mais complexas na medida em que cresce a população nas áreas urbanas. A utilização de técnicas de sistemas distribuídos para que múltiplos domínios de serviços usufruam da mesma infraestrutura computacional, pode auxiliar na eficiência das cidades, evitando gastos administrativos duplicados e até mesmo, possibilitando a correlação de eventos entre os serviços, favorecendo a identificação de fatores de causalidades e assim, a tomada de decisões administrativas mais objetivas e precisas. Neste contexto, este trabalho concentra-se na análise de um middleware direcionado à gestão de cidades para coleta, integração e interpretação dos dados de sensores, pertencentes aos serviços disponíveis da própria cidade, junto com os dados do sensoriamento colaborado pelos cidadãos. Para avaliação do conceito foi investigado o cenário de monitoração da conservação de vias públicas. Após 3 meses de coletas de dados por um sistema de sensoriamento automático, totalizando mais de 360 mil pontos e também mais de 90 relatórios pelo sensoriamento participativo, verificou-se que um sistema distribuído pode realizar a interpretação de séries históricas, engajar os munícipes apoiar a manutenção dos serviços da cidade e também indicar objetivamente aos gestores públicos os pontos que devem ser prioritariamente atendidos. Aliar ferramentas pelas quais o cidadão pode, de acordo com sua necessidade, convicção e altruísmo, exercer influência nos gestores públicos com o suporte de informação contínua e critérios objetivos das redes de sensores, pode estimular a continua excelência dos serviços públicos. / The cities in their own way and time are improving their services provided to the population. Among several factors that are contributing to this trend are the diversification and proliferation of sensors in various services domains of cities and new communication ways with citizens, for instance, social networks and more recently, crowdsensing systems, motivated by social expectations for better public services and the popularity of mobile devices. In this direction, administrative efficiency is a key factor, since the cities are proving more complex with increasing the population in urban areas. Techniques of distributed systems to share the same computing infrastructure to multiple service domains, can assist in the efficiency of cities, avoiding duplicate administrative costs and even allowing event correlation between services, providing the identification of causality factors, thus making management decisions more objective and accurate. In this context, this research focuses on analysis of a middleware directed to city management for collection, integration and interpretation of sensors data, present in city services, along with the sensing data contributed by citizens. For concept evaluation, was investigated the scenario of conservation of public streets. After 3 months of data collection by an automatic sensing system comprising more than 360 thousand points and also 94 reports of collaborative sensing, it was found that a distributed system can perform the interpretation of historical series; engage the citizens to support maintenance of city services and indicate objectively the points that should primarily be fix by public managers. Combining tools, which citizens can, according to their need, conviction, altruism, exert their own influence in public management and the continuous information support to objective criteria of sensor networks, can stimulate the continued excellence of public services.
147

Um sistema de alerta para o monitoramento remoto do consumo de energia usando redes de sensores sem fio / An alert for remote monitoring of energy consumption using wireless sensor networks

Rocha Filho, Geraldo Pereira 06 June 2014 (has links)
Determinar quais são os aparelhos eletrônicos de uma residência que possuem maior influência na conta de luz não é tarefa trivial. As Redes de Sensores Sem Fios (RSSF) auxiliam os usuários nessa tarefa, permitindo descobrir se há algum tipo de desperdício no ambiente monitorado e assim, auxiliá-los a fazer as devidas correções. Por isso, é fundamental usar nas smart grids métodos que detectam novidades, também conhecido como anomalias , de forma individual e autônoma, para os usuários quando algo anômalo surge no consumo de energia dos equipamentos eletrônicos. Tais anomalias podem surgir, por exemplo, quando um equipamento consome energia acima do esperado, o que pode indicar um defeito. Nesse contexto, este trabalho propõe um método inteligente, nomeado como Novelty Detection Power Meter (NodePM), para detectar as novidades no consumo de energia dos equipamentos eletrônicos monitorados por uma smart grid. O NodePM detecta as novidades considerando a entropia de cada equipamento monitorado, a qual é calculada com base em um modelo de cadeia de markov que é gerado através de um algoritmo de aprendizado de máquina. Para tanto, o NodePM é integrado a uma plataforma de monitoramento remoto de consumo de energia, que consiste de uma RSSF associada a uma aplicação em nuvem. Para validar o desempenho do NodePM foram feitos experimentos utilizando a análise de variância e testes paramétricos e não-paramétricos. Os resultados de tais experimentos, obtidos mediante a análise estatística, evidenciou a viabilidade do NodePM na plataforma desenvolvida / It is not a simple task to determine which pieces of elevtronic equipment have the greatest influence on the electricity bill. The Wireless Sensor Networks (WSN) assist users in this task, allowing to discover if there is any type of a waste in a monitored environment and thus, help them to take proper actions. Hence, it is of crucial importance to use intelligent methods in the smart grids for a novelty detection and to inform the users in an individual and autonomous way when some anomaly has occurred in the energy consumption of electronic equipment. These anomalies can arise, for instance, when a piece of equipment consumes more energy than expected. In this context, we propose an intelligent method, named the Novelty Detection Power Meter (NodePM), to detect the novelties in the energy consumption of electonic equipment monitored by a smart grid. The NodePM detects the novelties considering the entropy of each device monitored, which is calculed based on a Markov chain model that is generated through a machine learning algorithm. For this end, the NodePM is integrated into a platform for the remote monitoring of energy consumption, which consists of a WSN associated with a cloud application. To validate the performance of the NodePM, experiments were done using analysis of variance and parametric and non-parametric tests. The result of these tests, which were obtained from a statistical analysis, provided evidence of the feasibility of the NodePM in the platform that was developed
148

Rede de sensores sem fio em ambientes veiculares baseada no padrão Zigbee. / Wireless sensor network (WSN) in automotive area based in the standard ZigBee.

Florido, Ivan Roca 28 March 2008 (has links)
A área automotiva cada vez mais incorpora dispositivos e sistemas eletromecânicos na comunicação. Estes dispositivos são baseados nas informações internas e externas coletadas através de sensores específicos. Esta estrutura permite, por exemplo, a automatização de sistemas de transporte em ambientes controlados, monitoramento de veículos, informações de condições de trânsito e outros. Os protocolos de comunicação são fundamentais na troca de dados entre os módulos eletrônicos e certamente, se não fosse pela aplicação desses protocolos, não teríamos a integração de boa parte dos sistemas eletrônicos atualmente disponíveis. A integração dos sistemas de comunicação automotivos através de uma rede de sensores sem fio (RSSF) baseada nas especificações do padrão IEEE 802.15.4 ZigBee, constitui uma alternativa de comunicação nos ambientes automotivos. Além disso, esta integração em ambientes automotivos diminui a quantidade de fiação nos veículos. Neste trabalho apresentamos uma rede de sensores tipo estrela para a aquisição dos dados em um ambiente automotivo, realizando medições de intensidade do sinal, qualidade do sinal, throughput, pacotes perdidos. / The automotive area is including more and more devices and electromechanical systems at communication. Those devices are based in internal and external information collected through specific sensors. This structure allows, for example, automation of transport systems at controlled environments, vehicles monitoring, information of transit conditions and other. The communication protocols are fundamentals in data exchange between electronic modules and without those protocols, couldnt be possible integrate a majority of available electronic systems. The integration of automotive communication systems through wireless sensor network (WSN) based in the specifications of the standard IEEE 802.15.4 ZigBee constitute an alternative of communication in automotive environments. Besides, this integration in automotive environments reduces the quantity of wires in the vehicles. In this work we present a WSN star topology for data acquisition in automotive environment performing measurements of signal intensity, quality of signal, throughput, and lost packages.
149

Desenvolvimento de uma rede de sensores sem fio para processamento de sinais acústicos marinhos. / Development of a wireless sensor network for marine acoustic signals processing.

Durante, Gabriel 21 September 2018 (has links)
O crescente interesse pela caracterização de parâmetros acústicos marinhos esbarra nos poucos dispositivos eletrônicos que permitem capturar, armazenar, processar e difundir dados. Os equipamentos atuais que possibilitam obter dados referentes à vida marinha e permitem estudar as influências humanas sobre ela possuem alto custo e funcionam de forma isolada, ou seja, normalmente não há comunicação com outros dispositivos, o que dificulta a monitorização de eventos em tempo real. Sendo assim, neste trabalho são revisadas as características necessárias para estabelecer uma rede de sensores sem fio (RSSF) de alta confiabilidade, utilizando-se o conceito de Internet das Coisas (IoT). São comparados os protocolos MQTT-SN e CoAP com ferramentas de simulação e implementada uma rede de sensoriamento acústico aquático constituída de três nós sensores autônomos e um gateway usando o protocolo 6LowPAN. Também é implementada a tradução para o protocolo IPV4 no gateway, de modo que o funcionamento da rede de sensores pode ser monitorada num servidor remoto na Internet em tempo real. O desempenho da rede é avaliado com relação à autonomia energética, capacidade de memória, alcance e confiabilidade na entrega dos dados. As unidades autônomas desenvolvidas podem operar ininterruptamente, com uso de baterias, por aproximadamente 125 horas com memória de gravação de 48GB e alcance de 100m aproximadamente. Por fim, é implementado o pré-processamento dos dados sonoros visando a detecção de eventos acústicos aquáticos. / The increasing interest in the characterization of marine acoustic parameters needs electronic devices that allow capture, store, process, and diffuse data. Current equipment that provides data about the marine life and allow the study of human influences on it have high cost and work isolated, that is, without communication with other devices, which makes it difficult to monitor events in real time. Therefore, this work revises the necessary features to establish a high reliability wireless sensor network (WSN) by applying the concept of Internet of Things (IoT). The protocols MQTT-SN and CoAP are compared with simulation tools and a network is implemented to sense acoustic signals, composed by three autonomous sensor nodes and a gateway using the protocol 6LowPAN. The translation for the IPV4 protocol in the gateway is also implemented, so the operation of the sensor network can be monitored by a remote server on the Internet in real time. The performance of the network is evaluated in relation to power autonomy, memory capacity, reach and reliability. The autonomous sensor nodes can operate uninterrupted, with use of batteries, for approximately 125 hours with 48GB storage for recording and approximately 100m range. Finally, data pre-processing is implemented in order to detect aquatic acoustic events.
150

Utilização de data warehouses para gerenciar dados de redes de sensores sem fio que monitoram polinizadores. / The use of data warehouse to manage data from wireless sensors network that monitor pollinators.

Costa, Ricardo Augusto Gomes da 19 August 2011 (has links)
Este trabalho tem como objetivo a aplicação do conceito de data warehouse para a agregação, gerenciamento e apresentação de dados coletados por meio de Redes de Sensores Sem Fio que monitoram polinizadores. Os experimentos científicos que utilizam tais redes para monitorar habitat geram um volume de dados que precisa ser tratado e analisado, para que possa auxiliar os pesquisadores e demais interessados nas informações. Tais dados, gerenciados e correlacionados com informações de outras fontes, podem contribuir para a tomada de decisões e ainda realimentar outros experimentos. Para a avaliação da proposta, desenvolveu-se um modelo para extração, transformação e normalização dos dados coletados por redes de sensores sem fio, contemplando ainda a carga em data warehouse. Considerou- se no modelo, dados tabulados das redes de sensores sem fio, utilizados em experimentos com abelhas e ainda dados de outras fontes sobre o cultivo de abelhas, importantes para obtenção de visões do data warehouse mais apuradas. O uso de data warehouse aplicado a esse contexto mostrou-se um alternativa viável e útil, pois facilitou a obtenção de dados consolidados sobre o experimento, importante para a tomada de decisão pelos pesquisadores e ainda, diminui o tempo gasto pelos interessados em extrair essas informações, em comparação à tradicional análise em planilhas eletrônicas. / This work aims at applying the concept of data warehouse for data aggregation, management and presentation of data collected by Wireless Sensor Networks that monitor pollinators. Scientific experiments using such networks to monitor habitat generate a volume of data that must be addressed and analyzed, so that they can help researchers and others interested in the information. This data, managed and correlated with information from other sources may contribute to the making and still replenish other experiments. For the evaluation of the proposal, it was developed a model for the extraction, processing and standardization of data collected by wireless sensor networks, covering also the load on the data warehouse. It was considered in the model tabulated data networks of wireless sensors, used in experiments with bees and even data from other sources on the cultivation of bees, important to obtain views of the data warehouse more accurate. The use of data warehouse implemented in this context proved to be a viable and useful, as it facilitated the obtaining of information for decision making by researches and stakeholders and reduces time consumed by stakeholders to extract such information.

Page generated in 0.0663 seconds