• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3181
  • 859
  • 430
  • 391
  • 382
  • 254
  • 100
  • 84
  • 56
  • 54
  • 51
  • 50
  • 24
  • 16
  • 16
  • Tagged with
  • 7006
  • 1819
  • 1682
  • 1127
  • 862
  • 755
  • 654
  • 506
  • 480
  • 459
  • 444
  • 424
  • 408
  • 389
  • 372
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

A multi-channel defense against communication denial-of-service attacks in wireless networks

Alnifie, Ghada Matooq. January 2008 (has links)
Thesis (Ph.D.)--George Mason University, 2008. / Vita: p. 152. Thesis director: Robert Simon. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer Science. Title from PDF t.p. (viewed Jan. 8, 2009). Includes bibliographical references (p. 144-151). Also issued in print.
62

Service-differentiated and reliable communication in event-based wireless sensor networks

Xue, Yuyan. January 2010 (has links)
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2010. / Title from title screen (site viewed July 8, 2010). PDF text: 179 p. : col. ill. ; 13 Mb. UMI publication number: AAT 3397143. Includes bibliographical references. Also available in microfilm and microfiche formats.
63

New analytical applications of gold nanoparticles

Kurniawan, Fredy January 2008 (has links)
Regensburg, Univ., Diss., 2008.
64

New fluorescent optical pH sensors with minimal effects of ionic strength

Weidgans, Bernhard M. January 2004 (has links) (PDF)
Regensburg, Univ., Diss., 2004.
65

Multimodal Movement Sensing using Motion Capture and Inertial Sensors for Mixed-Reality Rehabilitation

January 2010 (has links)
abstract: This thesis presents a multi-modal motion tracking system for stroke patient rehabilitation. This system deploys two sensor modules: marker-based motion capture system and inertial measurement unit (IMU). The integrated system provides real-time measurement of the right arm and trunk movement, even in the presence of marker occlusion. The information from the two sensors is fused through quaternion-based recursive filters to promise robust detection of torso compensation (undesired body motion). Since this algorithm allows flexible sensor configurations, it presents a framework for fusing the IMU data and vision data that can adapt to various sensor selection scenarios. The proposed system consequently has the potential to improve both the robustness and flexibility of the sensing process. Through comparison between the complementary filter, the extended Kalman filter (EKF), the unscented Kalman filter (UKF) and the particle filter (PF), the experimental part evaluated the performance of the quaternion-based complementary filter for 10 sensor combination scenarios. Experimental results demonstrate the favorable performance of the proposed system in case of occlusion. Such investigation also provides valuable information for filtering algorithm and strategy selection in specific sensor applications. / Dissertation/Thesis / M.S. Electrical Engineering 2010
66

Desenvolvimento de sensor inteligente contendo indicadores de H2S / Development of intelligent sensor containing H2S indicators

Kato Junior, Edison Tutomu, 1978 07 December 2013 (has links)
Orientadores: Telma Teixeira Franco, Cristiana Maria Pedroso Yoshida / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T11:24:55Z (GMT). No. of bitstreams: 1 KatoJunior_EdisonTutomu_D.pdf: 14133160 bytes, checksum: 4ca041ce9eb1c6a78d7e55bb1e39489f (MD5) Previous issue date: 2013 / Resumo: Um sensor inteligente foi desenvolvido neste estudo, visando detectar a presença de gás sulfídrico (H2S). A aplicação deste sensor pode ser abrangente, desde aplicações em controle de vazamentos na indústria petroquímica, até o controle de qualidade de produtos alimentícios, uma vez que o H2S é um dos metabólitos liberado por microrganismos contaminantes em condições de anaerobiose. Este sistema tem a função de comunicar a presença de H2S no caso de vazamentos na linha de recuperação em pontos críticos (juntas, válvulas, conecções, etc.) ou informar ao consumidor possíveis alterações microbiológicas no produto durante o transporte e armazenamento, indicando o estado de frescor do produto. O sensor biodegradável e inteligente foi desenvolvido a partir de filmes de quitosana, um polímero natural proveniente do descarte da indústria pesqueira, biodegradável e capaz de formar filmes resistentes, flexíveis e com eficiente barreira a oxigênio. A incorporação dos indicadores de H2S produz um sinal colorimétrico como uma reposta rápida para a presença deste composto. O objetivo deste estudo consistiu na obtenção do sensor inteligente com indicadores de presença de H2S, na caracterização do sensor quanto suas propriedades mecânicas, correlação da gramatura calculada/prática e capacidade de absorção de água, aplicação e avaliação de eficiência do sensor em ambiente real na análise da identificação de contaminação microbiológica e análises visando caracterizar a interação entre o indicador colorimétrico e a matriz de quitosana. O presente trabalho deu origem ao depósito de uma patente junto ao INPI no dia 18 de dezembro de 2009, sob o número de protocolo 018090056144 e junto ao Patent Cooperation Treaty (PCT) no dia 24 de novembro de 2010, sob o número do processo internacional PCT/BR2010/000394 / Abstract: A smart sensor was developed in this study to detect the presence of hydrogen sulphide gas (H2S). This sensor can be applied for leakage control in the petrochemical industry and also in quality control of food products, once the H2S is one of the metabolites released by contaminating microorganisms under anaerobic conditions. This system has the function of communicating the presence of H2S in the case of leaks in the recovery line at critical points (seals, valves, connections, etc.) in petrochemicals. It can inform the consumer possible microbiological changes in the product during transport and storage, indicating the state of freshness of the product. The biodegradable and smart sensor was developed using chitosan, a natural polymer derived from the disposal of the fishing industry, biodegradable and capable of forming resistant, flexible films and efficient barrier to oxygen. The accumulation of trash of hard degradation is increasing worldwide. The incorporation of H2S indicators produces a colorimetric signal as a rapid response to the presence of this compound. The aim of this study was to obtain intelligent sensors with H2S indicators, the characterization of the sensor as its mechanical properties, correlation of the calculated thickness / practice and ability to absorb water, efficienty evaluation in a real environment on the analysis of the identification of microbiological contamination and analysis to characterize the interaction between the chitosan matrix and the colorimetric indicator / Doutorado / Engenharia Química / Doutor em Engenharia Química
67

Desarrollo de un Sensor Virtual de Ley de Concentrado Rougher en Planta Las Tórtolas

Barrera Páez, Rodrigo Andrés January 2007 (has links)
No description available.
68

Design and Implementation of Broad Band and Narrow Band Antennas and Their Applications

Salmani, Zeeshan 08 1900 (has links)
The thesis deals with the design and implementation of broadband and narrowband antennas and their applications in practical environment. In this thesis, a new concept for designing the UWB antenna is proposed based on the CRLH metamaterials and this UWB antenna covers a frequency range from 2.45 GHz to 11.6 GHz. Based on the design of the UWB antenna, another antenna is developed that can cover a very wide bandwidth i.e from 0.66 GHz to 120 GHz. This antenna can not only be used for UWB applications but also for other communication systems working below the UWB spectrum such as GSM, GPS, PCS and Bluetooth. The proposed antenna covering the bandwidth from 0.66 GHz to 120 GHz is by far the largest bandwidth antenna developed based on metamaterials. Wide band antennas are not preferred for sensing purpose as it is difficult to differentiate the received signals. A multiband antenna which can be used as a strain sensor for structural health monitoring is proposed. The idea is to correlate the strain applied along the length or width with the multiple resonant frequencies. This gives the advantage of detecting the strain applied along any direction (either length or width), thus increasing the sensing accuracy. Design and application of a narrow-band antenna as a temperature sensor is also presented. This sensor can be used to detect very high temperature changes (>10000C). This sensor does not require a battery, can be probed wirelessly, simple and can be easily fabricated, can withstand harsh environmental conditions.
69

Dynamically Controllable Applications in Wireless Sensor Networks

Rajan, Sriram 13 May 2006 (has links)
Applications for Wireless Sensor Networks can be updated dynamically by means of wireless upgrade mechanisms. Current research efforts in wireless upgrade mechanisms for WSN have focused on transmitting application packets for upgrades via wireless medium. However, these schemes require significant overhead involved in sending and receiving application packets that affect the sensor operation, in addition to bringing the nodes down to reprogram and restart them. By designing applications in a way that allows dynamic functionality changes during operation, the overhead and sensor delays can be eliminated. Dynamically Controllable Application (DCA) is a novel scheme for designing WSN applications whose behavior can be rapidly and dynamically changed during operation. The results indicate that a veritable functionality change is achieved in a span of a few milliseconds.
70

Investigation of Two Polarimetric Optical Strain Sensors

Vulovic, Boris 03 1900 (has links)
This thesis presents a theoretical description and experimental testing of two polarimetric fiber-optic strain sensors. 'The first .of these is an intrinsic sensor in which a single mode optical fiber acts as the sensing element. This sensor exhibited low strain sensitivity and high cross-sensitivity to temperature. The second sensor was of the extrinsic type, A single polarization maintaining fiber was used to deliver and collect light from the sensing element, which a was piece of photoelastic sheet PS-1. This type of sensor exhibited large dynamic range of 1:1350, resolution of 0.59ps, and strain sensitivity of the normalized signal of0.00219pe+1. / Thesis / Master of Engineering (ME)

Page generated in 0.0285 seconds