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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

Radiation damage studies of silicon detectors

Sotthibandhu, Sakuntala January 1994 (has links)
No description available.
242

The asymmetry of the '1'2C(#gamma# #->#,pn) reaction

Franczuk, Stefan January 1998 (has links)
No description available.
243

Angular distribution of '1'2C(#gamma#, NN) reactions

Yau, Tony Tsz-Hong January 1996 (has links)
No description available.
244

Particle detection with superconducting phonon sensors

Hahn, Andreas January 1994 (has links)
No description available.
245

Tunneled data transmission over wireless sensor networks

Yow, Thiam Poh 12 1900 (has links)
A technique for terminal communication through transmission links established across a wireless sensor network is developed and tested. Using protocols established for conventional wireless communication networks as a guiding principle, different methodologies for link management, and segmentation and reassembly of information are explored. A protocol for sensor network encapsulation was designed and implemented across a network of terminals and wireless sensor motes. The study concludes with a discussion of the capabilities and limitations of this technique supported by results obtained through experiments under various scenarios. / Singapore Army author.
246

Design of a bore sight camera for the lineate image near ultraviolet spectrometer (LINUS)

Cabezas, Rodrigo. 06 1900 (has links)
Approved for public release; distribution is unlimited. / The Lineate Image Near Ultraviolet Spectrometer (LINUS) is a spectral imager that works in the ultraviolet region of the spectrum. This thesis describes the latest of several steps in the development of this instrument. Due to the narrow field of view of the instrument, 2.5 x 0.5 degrees, an accurate pointing method is necessary; also, a scheme of quality evaluation of the post-processed spectral image is desirable. A way to achieve both goals was developed by designing and implementing the layout for two visual cameras, wide and narrow field of view, and a method to capture the images in order to perform the subsequent comparison with the processed spectral image. Since this is the first time the system is working in full-automated mode, a new wavelength calibration with the emission lines from a platinum hollow cathode lamp was performed and a new response curve for sulfur dioxide (SO2) was taken. Finally, laboratory and outdoor field observations were conducted to test the system integration. / Lieutenant, Chilean Navy
247

The Effect of Crystal Defects on the Performance of High-flux CZT X-ray Detectors

Sadeghi, Niloofar 09 October 2015 (has links)
Cadmium Zinc Telluride (CZT) has been one of the most promising semiconductor materials for many years. Due to its high atomic number, suitable band-gap energy and ability to function at room temperature, CdZnTe has become the material of choice to be used as a room temperature radiation detector for many applications in the fields of medical imaging, process monitoring and national security, where demands and specifications set by those applications require that these detectors can operate well at the extreme conditions while maintaining good resolution, high detection efficiency, good reliability and high throughput. In most applications, detectors are exposed to high flux of X-ray radiation. One of the most common issues is the degradation of these detectors due to the presence of extended and point defects, which can act as traps for the charge carriers. This charge trapping causes the build-up of space charge and disturbing the electric field, resulting incomplete charge collection and signal formation of the detectors. This thesis investigates the associated failure modes by identifying the types of defects that exist in the CZT crystal and studies their roles in the performance of X-ray radiation detectors using in-house diagnostic tools. The results from different screening methods are compared and studied in order to find meaningful relationships and correlations that will help researchers to better understand the underlying physics and provide information and means for corrections and improvements of the crystal quality. / Graduate
248

A novel facial action intensity detection system

Bingol, Deniz 30 January 2015 (has links)
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. October 2014. / Despite the fact that there has been quite a lot of research done in the eld of facial expression recognition, not much development has occurred in detecting the intensity of facial actions. In facial expression recognition, the intensity of facial actions is an important and crucial aspect, since it would provide more information about the facial expression of an individual, such as the level of emotion in a face. Furthermore, having an automated system that can detect the intensity of facial actions in an individual's face can lead up to a lot of potential applications from lie detection to smart classrooms. The provided approach includes robust methods for face and facial feature extraction, and multiple machine learning methods for facial action intensity detection.
249

Eletrodos impressos modificados com poli-histidina aplicados na construção de sensores eletroquímicos para crômio(VI) e fármacos /

Bergamini, Márcio Fernando. January 2007 (has links)
Orientador: Maria Valnice Boldrin Zanoni / Banca: Hideko Yamanaka / Banca: Orlando Fatibello Filho / Banca: Mauro Bertotti / Banca: Auro Atsushi Tanaka / Resumo: O presente trabalho investiga a aplicação de eletrodos impressos, de carbono (SPCE) e ouro (SPGE), na determinação de espécies de interesse farmacêutico, tais como, aurotiomalato, L-dopa e procaína, utilizando sistemas convencionais, com fluxo de solução e análise por injeção em fluxo, respectivamente. Após a otimização de todos os parâmetros voltamétricos e inerentes da técnica construí-se curvas analíticas para cada composto farmacêutico com respostas lineares entre concentrações de 1,4 x 10-6 a 1,5 x 10-4 mol L-1, 1,5 x 10-6 a 6,6 x 10-4 mol L-1 e 1,0 x 10-5 a 1,0 x 10-4 mol L-1 para o aurotiomalato, a L-dopa e a procaína, respectivamente. O método foi aplicado na determinação dessas espécies em formulações farmacêuticas. A construção e caracterização voltamétrica de. eletrodos de carbono impresso (SPCE) por filmes de poli-histidina (PH) foi também investigada com intuito de ampliar o nível de sensibilidade e seletividade dos métodos voltamétricos. Para isso, foram testados três diferentes procedimentos de para a construção dos eletrodos modificados: a adição direta de uma solução do polímero (SPCE/PH), a utilização de uma reação cruzada entre a poli-histidina e o glutaraldeído (SPCE/Glu-PH) e a eletropolimerização a partir do monômero histidina (SPCE/EPH). O comportamento voltamétrico dos eletrodos modificados mostrou-se fortemente dependente do procedimento de preparação dos filmes. Eletrodos SPCE/PH e SPCE/Glu-PH apresentaram uma alta eficiência na pré-concentração de ânions, como o ferricianeto. Não sendo observado nenhum efeito eletrocatalítico para a oxidação de ácido ascórbico com esses eletrodos. Já para o SPCE/EPH foi observado um baixo desempenho na pré-concentração de ânions, mas um pronunciado efeito eletrocatalítico para a oxidação de ácido ascórbico. A aderência e estabilidade das respostas obtidas...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present work investigated the application of screen-printed carbon (SPCE) and screen-printed gold electrodes (SPGE) in the determination of species of pharmaceutical interest, such as, aurothiomalate, L-dopa and procaine. The performance of all electrodes was tested in a conventional electrochemical system, and also in two electrochemical cells using amperometric detection. The first one was constructed to operate on hydrodynamic system and the second one to work on flow injection analysis (FIA) system. Analytical curves were obtained for all systems with linear relationship from peak current vs concentration from 1.4 x 10-6 to 1.5 x 10-4 mol L-1 for aurothiomalate; 1.5 x 10-6 to 6.6 x 10-4 mol L-1 for L-dopa and 1.0 x 10-5 to 1.0 x 10-4 mol L-1 for procaine, respectively. The method was tested in pharmaceutical compounds with good recovery. Screen-printed carbon electrodes (SPCE) can be easily modified with poly-histidine (PH) films using three different procedures: by direct addition of a poly-histidine solution on the electrode surface (SPCE/PH), using a cross-link reaction between poly-histidine and glutaraldehyde (SPCE/Glu-PH) and by electropolymerization of the histidine monomer (SPCE/EPH). The voltammetric behavior of the three modified electrodes was evaluated using potassium hexacyanoferrate(III) and ascorbic acid as model compounds. All modified electrode from stable films, but SPCE coated by deposition of PH and Glu-PH presented higher efficiency for pre concentration anions, while SPCE coated by electropolymerization of the monomer (EPH) presented pronounced electrocatalytic effect in the ascorbic acid oxidation. The resulting PH films presented good adherence and high stabilities and they were applied in the voltammetric analysis of isoniazide, pyrazinamide, aurothiomalate and chromium (VI). The best experimental condition for isoniazide and pyrazinamide...(Complete abstract click electronic access below) / Doutor
250

Estudo e desenvolvimento de sensores biomiméticos baseados em materiais carbonáceos modificados com ftalocianinacobalto (II) para detecção amperométrica de metribuzin /

Figueira, Eduardo Carneiro. January 2012 (has links)
Orientador: Maria Del Pilar Taboada Sotomayor / Banca: Iara Lucia Tescarollo Dias / Banca: Emerson Schwingel Ribeiro / Resumo: O presente trabalho está baseado na construção de sensores biomiméticos para monitoramento sensível e seletivo do agrotóxico metribuzin (MTZ). Para isto, eletrodos à base de pasta de carbono e nanotubos de carbono foram modificados com diversos complexos potenciais catalisadores biomiméticos das enzimas P450, que são enzimas que catalisam um grande número de reações incluindo os agrotóxicos. O complexo que apresentou perfil biomimético e melhores resultados na determinação amperométrica do metribuzin foi à ftalocianinacobalto (II) [CoPc]. Quando construídos sensores à base de pasta de carbono modificada com CoPc, os melhores resultados foram obtidos usando 15% (m/m) de complexo na preparação da pasta e realizando as medidas em tampão Britton-Robinson 0,08 mol L-1 (pH 2,0), aplicando potencial de -690 mV vs Ag|AgCl. Sob estas condições obteve-se uma faixa linear de resposta de 2,4 x 10-5 a 2,0 x 10-4 mol L-1, com uma boa sensibilidade e LOD e LOQ de 4,3 x 10-6 e 1,4 x 10-5 mol L-1, respectivamente. Estudos relacionados a elucidar a biomimeticidade do sensor, incluíram avaliação da influência da velocidade de varredura empregando voltametria cíclica, exploração do perfil hiperbólico da resposta do sensor e estudo de interferentes e de seletividade. A seguir, foi avaliada a influencia de nanotubos de carbono de paredes múltiplas (MWCNT) na preparação da pasta no intuito de tentar aumentar a detectabilidade do sensor modificado com ftalocianinacobalto (II). Entretanto, os resultados obtidos não foram àqueles esperados, devido principalmente, à grande quantidade de material aglutinante (Nujol® que é isolante) necessário para a obtenção da pasta. Assim, a seguir, foi realizada a avaliação de eletrodos impressos à base de grafite, contendo MWCNT a 0,3% e CoPc a 5%, 10% e 15% (m/m). Sob as condições de... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work is based on the construction of biomimetic sensors for monitoring sensitive and selective pesticide metribuzin (MTZ). For this, the base electrodes of carbon paste and carbon nanotubes have been modified with various complex catalysts potential biomimetic of P450 enzymes, which are enzymes that catalyze a large number of reactions including pesticides. The complex profile that showed better results in biomimetic and amperometric determination of metribuzin was the ftalocianinacobalto (II) [CoPc]. When constructed sensors based on a modified carbon paste CoPc with the best results were obtained using 15% (m/ m) complex in the preparation of the folder and making the measurements in Britton-Robinson buffer 0,08 mol L-1 (pH 2,0), by applying potential to -690 mV vs Ag | AgCl. Under these conditions gave a linear response range of 2.4 x 10-5 to 2.0 x 10-4 mol L-1, and with good sensitivity and LOQ and LOD of 4,3 x 10-6 and 1 , 4 x 10-5 mol L-1, respectively. Related studies to elucidate the biomimeticidade sensor, included evaluation of the influence of scan rate using cyclic voltammetry, exploitation of hyperbolic profile of the sensor response and the study of interferences and selectivity. Next, we evaluated the influence of carbon nanotubes multi-walled (MWCNT) in the preparation of the folder in order to try to increase the detectability of the sensor modified with ftalocianinacobalto (II). However, the results were not those expected, mainly due to the large amount of binder material (Nujol ® which is an insulator) necessary for obtaining the paste. Thus, the following evaluation was made electrodes printed based on graphite containing MWCNT CoPc 0,3% and 5%, 10% and 15% (m / m). Under the above conditions optimized for the analysis carbon paste, the printed electrode that provided the best... (Complete abstract click electronic access below) / Mestre

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