In this study the relationship between the dynamic response of the flexible substrate and the power generation for energy harvesting system is proposed. High electro-mechanical transformation of piezoelectric materials, high efficient energy transfer of mechanical structure and controlled circuit make the piezoelectric generator a high performance. The devices of cantilevers with lump structures on the flexible substrate and piezoelectric film (ZnO) are designed. Then some individual layers of power generator are stocked in parallel to form a multi-layer system with a broad resonant band width. When the generator is operated in a wide frequency range vibration environment, the multi-layer piezoelectric films in the form of cantilever structures can induce current. First the finite element method for the piezoelectric cantilever beam is constructed by using ANSYS software. Both modal analysis and harmonic response analysis are performed to obtain the structural modal parameters and frequency response functions, respectively. Besides, the beam structure is modeled by 3D coupled field piezoelectric element. This research will apply Taguchi¡¦s method to design including variations of dimensions and material properties for energy harvesting system. The flexible substrate is polymeric film (PET). Imprinting process is applied to transfer the simulated geometric configuration onto a flexible substrate to obtain a maximum power output. The results show the single devices can improve efficiently by using lump structures on the flexible substrate, the generator could achieve maximum OCV of 2.25V which is 0.276£gW every centimeter squared when attached to a stable source of vibration. The multi-layer system can be used in 50~500Hz of low frequency environment. Furthermore, the output voltage (OCV) is upward when the flexible substrate with low Young¡¦s modulus.

p. 1-110 / Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-03-07T19:10:39Z No. of bitstreams: 1 88888q.pdf: 1473667 bytes, checksum: 7db700f83e8b6688927f7d2e24326d50 (MD5) / Approved for entry into archive by Tatiana Lima(tatianasl@ufba.br) on 2013-03-13T18:47:29Z (GMT) No. of bitstreams: 1 88888q.pdf: 1473667 bytes, checksum: 7db700f83e8b6688927f7d2e24326d50 (MD5) / Made available in DSpace on 2013-03-13T18:47:29Z (GMT). No. of bitstreams: 1 88888q.pdf: 1473667 bytes, checksum: 7db700f83e8b6688927f7d2e24326d50 (MD5) Previous issue date: 2006 / Atualmente, a investigação sobre a satisfação dos clientes em serviços tem tido grande destaque, tanto no meio acadêmico quanto empresarial. Inúmeras pesquisas revelam a importância desses estudos para o desenvolvimento e o crescimento das empresas. Esta pesquisa investigou a satisfação do cliente de telefonia por banda larga (Velox) da Telemar, em Salvador, nos bairros que mais utilizam esse serviço. Através da aplicação de um roteiro de entrevistas semi-estruturado, buscamos identificar a satisfação do cliente em relação às principais dimensões do serviço, a saber: (1) desempenho do serviço; (2) relação custo-benefício, (3) central de atendimento; (4) reparo técnico. A pesquisa verificou ainda que, de maneira geral, a satisfação do cliente com o serviço de banda larga da Telemar pode ser considerada muito boa. Em todas as dimensões, exceto a relação custo - benefício, a maioria dos clientes se declarou bastante satisfeita. / Salvador

Les antennes reconfigurables offrent de multiples fonctions en changeant dynamiquement leurs propriétés telles que la fréquence de fonctionnement, la polarisation, le diagramme de rayonnement ou toute combinaison de ces trois paramètres. Leur agilité et leur diversité créent de nouvelles possibilités d'applications pour les systèmes radio tels que les réseaux locaux, les liaisons par satellite et notamment la radio cognitive. Dans cette thèse, deux antennes reconfigurables en fréquence fonctionnant dans les bandes des standards sans fil actuels ont été proposées. Elles sont basées sur la modification de la géométrie du patch rayonnant. Leurs dimensions ont été optimisées par algorithmes génétiques embarqués et combinés à un logiciel de simulation électromagnétique. La commande de la reconfiguration de ces antennes est réalisée à l'aide d'un microcontrôleur qui pilote l'état des commutateurs (des diodes PIN). De ce fait, un système d'antenne reconfigurable intelligent dédié à la radio cognitive a été développé. / Reconfigurable antennas offer multiple functions by dynamically changing their properties such as operating frequency, polarization, radiation pattern, and a combination of all these factors. Their agility and diversity create a wide range of different and new applications for radio systems such as local networks, satellites, and especially in cognitive radio. In this thesis, two new frequency reconfigurable antennas are proposed. The frequency reconfiguration is obtained by changing the geometry of radiating patch. Their dimensions have been optimized by genetic algorithm embedded in the electromagnetic simulation software. These antennas operate at the frequency band for IEEE 802.11b/g standard with satisfactory radiation characteristics. This thesis also presents a method of controlling the operation of the frequency reconfigurable antenna by a micro-controller. The operation of electronic switches (PIN diodes) are carried out through programs which allows an adaptive operating system like smart antennas and work well in cognitive radio environment.

Novel applications of optical analytical techniques have been demonstrated in three general areas, namely application of broadband cavity enhanced absorption spectroscopy (BBCEAS) to the detection of liquid phase analytes, the use of total luminescence spectroscopy to discriminate between different type of teas and the development of an optical sensor to detect ammonia gas, based on the fluorescence quenching of a dye immobilised in a sol gel matrix. A simple BBCEAS setup has been developed with a view to perform sensitive visible wavelength measurements on liquid phase solutions. In the present work a simple low-cost experimental setup has been demonstrated for the measurement of the visible spectra of representative liquid-phase analytes in a 2 mm quartz cuvette placed at normal incidence to the cavity mirrors. Measurements on Ho3+ and sudan black with a white LED and the R ≥ 0.99 mirrors covered a broad wavelength range (~250 nm) and represents the largest wavelength range covered to date in a single BBCEAS experiment. The sensitivity of the technique as determined by the best αmin value was 5.1 x 10-5 cm-1 and was obtained using the R ≥ 0.99 mirrors. The best limit of detection (LOD) for the strong absorber brilliant blue-R, was approximately 620 pM. The optical setup was then optimised for the application of BBCEAS detection to an HPLC system. A 1 cm pathlength HPLC cell with a nominal volume of 70 ml was used in this study. The cavity was formed by two R ≥ 0.99 plano-concave mirrors with a bandwidth of ~ 420 – 670 nm. Two analytes rhodamine 6G and rhodamine B were chosen for separation by HPLC, as they were chemically similar species with distinctive visible spectra and would co-elute in an isocratic separation. The lowest value of amin obtained was 1.9 x 10-5 cm-1. The most significant advantage of the HPLC-BBCEAS study over previous studies arose from the recording of the absorption spectrum over a range of wavelengths. It was demonstrated that the spectral data collected could be represented as a contour plot which was useful in visualising analytes which nearly co-eluted. The LOD values for the two analytes studied indicated that the developed HPLC-BBCEAS setup was between 54 and 77 times more sensitive than a commercial HPLC system. For improved sensitivity and lower detection limits the low cost BBCEAS setup was used with a significantly longer 20 cm pathlength cell where the mirrors were in direct contact with the liquid phase analyte. This also reduced interface losses. The experiments were carried out using both R ³ 0.99 and R ³ 0.999 mirrors. The lowest αmin value obtained in this study was 2.8 x 10-7 cm-1 which is the lowest reported value to date for a liquid phase measurement, making this study the most sensitive liquid phase absorption measurement reported. The lowest LOD recorded was 4.6 pM, and was obtained for methylene blue with the R ³ 0.999 mirrors. A novel application of total luminescence spectroscopy to discriminate between different types of teas objectively was also investigated. A pattern recognition technique based on principal component analysis (PCA) was applied to the data collected and resulted in discrimination between both geographically similar and dissimilar teas. This work has shown the potential of fluorescence spectroscopy to distinguish between seven types of teas from Africa, India, Sri Lanka and Japan. Geographically similar black teas from 15 different plantation estates in Sri Lanka were also studied. The visualisation technique allowed the separation of all 11 types of teas when the first two principal components were utilised. The final part of the thesis describes the development of an optical sensor for the detection of ammonia gas. The operation of the sensor depended on the fluorescence quenching of the dye 9 amino acridine hydrochloride (9 AAH) immobilised in a sol gel matrix. It was also shown that the sensor response was not affected by the presence of acidic gases such as HCl and SO2. The final version of the sensor made use of dual channel monitoring to improve the sensitivity of the sensor. Measurements using diluted mixtures of ammonia gas in the range 5 -70 ppm showed that the response of the sensor was nonlinear, with the sensitivity increasing at lower concentrations. The measurement of the baseline noise allowed the LOD to be estimated at ~400 ppb.

Made available in DSpace on 2014-12-17T14:55:33Z (GMT). No. of bitstreams: 1 FlaviaCC_Capa_ate_pag15.pdf: 8751469 bytes, checksum: df79b8a134d4a6869e65f7ed508775af (MD5) Previous issue date: 2009-11-17 / ln this work, planar quasi- Y agi antennas are investigated based on the concept of the classic Y agi_Uda antennas. These antennas represent improvements on the topologies of the antennas existing printed because they present characteristics of broad bandwidth, excellent radiation diagrams and simple construction. New configurations are adapted for the driver of the antennas, introducing patches elements into the driver. These new configurations are named Patches Elements Anteonas (PEA). This adaptation is obtained from simulations that are executed usiog the software C8T Microwave 8tudio 5. After doing the optimizations, procedures for construction and measurement ofthe prototypes are executed in order to improve the performance of the antennas in such way that they could be used in wireless communication applications, such as Bluetooth, WLAN' s and Wi-Fi. Next, the quasi- Y agi antennas are studied in order to implement them in arrangements. The arrangements construction is based 00 the best driver configuration of the antenna developed in this work. First, a linear arrangement composed by two elements of quasi?Yagi antennas is constructed in such way that the radiation characteristics and the mutual coupling effects could be analyzed. After that, a 90? angle arrangement composed by two elements is studied to observe the effect of circular polarization. Experiments are executed in order to evaluate the arrangements performance. The experimental results show that the analysis made in this work is efficient and accurate. The numerical values obtained for the analyzed parameters of each structure developed are compared with the experimental values. 80, it is possible to observe a good concordance between them. Finally, some future works proposals are presented / Neste trabalho, antenas planares quasi-Yagi s?o estudadas com base no conceito das antenas Yagi-Uda cl?ssicas. Estas antenas representam melhorias sobre as topologias das antenas impressas existentes por apresentarem caracter?sticas de banda larga, excelentes diagramas de irradia??o e constru??o simples. Novas configura??es s?o adaptadas para o driver das antenas, introduzindo elementos patches sobre o driver. Essas novas configura??es s?o chamadas de Antenas de Elementos Patches (AEP). Esta adapta??o ? obtida realizando simula??es de otimiza??o com o aux?lio do software CST Microwave Studio 5. Ap?s as otimiza??es, procedimentos para constru??o e medi??o dos prot?tipos s?o realizados com o objetivo de melhorar o desempenho das antenas para aplica??es de comunica??es sem fio, tais como Bluetooth, WLAN's e Wi-Fi. Posteriormente, as antenas quasi- Yagi s?o estudadas com o intuito de implement?-Ias em arranjos. A constru??o dos arranjos baseia-se na melhor configura??o do driver da antena desenvolvida por este trabalho. Primeiramente, um arranjo linear com dois elementos de antenas quasi-Yagi ? constru?do de tal forma que as caracter?sticas de irradia??o e o efeito do acoplamento m?tuo pudessem ser analisados. Em seguida, um arranjo composto por dois elementos dispostos sob um ?ngulo de 900 ? estudado para se observar o efeito da polariza??o circular. Experimentos s?o executados para avaliar o desempenho dos arranjos. Os resultados dos experimentos demonstram que a an?lise efetuada neste trabalho ? eficiente e precisa. Os valores num?ricos obtidos para os par?metros analisados em cada estrutura desenvolvida s?o comparados com os valores experimentais. Com isso, ? poss?vel observar uma boa concord?ncia entre eles. Por fim, algumas propostas para a realiza??o de trabalhos futuros s?o apresentadas