A avaliação dos sistemas de fornecimento de energia para o futuro é da maior importância para se obter informações sobre o potencial de impacto ambiental dos vários estágios do ciclo de vida das tecnologias inovadoras, determinando as vantagens competitivas sobre as tecnologias convencionais e para o desenvolvimento de cenários futuros. Este trabalho apresenta e caracteriza os tipos de pilhas combustíveis de média e baixa temperatura mais pesquisadas e comercializadas nos últimos anos. Realiza-se também a apresentação da avaliação do impacto ambiental dos principais materiais utilizados nas pilhas a combustível, considerando as fases de fabricação, operação e disposição final após o término da vida útil. São apresentados vários dados de LCA (Life Cycle Assessment) efetuados para alguns tipos de pilhas. O trabalho efetuou uma contribuição ao estudo da avaliação de impacto ambiental das pilhas a combustível de média e baixa temperatura utilizando a metodologia Delphi. Foi construído um questionário e um banco de dados para formação do conjunto de respondentes que participaram da pesquisa. Eles receberam o questionário na primeira rodada e o responderam. Depois receberam novamente o questionário em conjunto com as respostas obtidas na primeira etapa, para nova rodada de respostas. Ao final o estudo verifica se ocorreu aumento de consenso e a influência dos respondentes mais qualificados sobre os menos qualificados. Os resultados mostraram que os respondentes acreditam numa redução do impacto ambiental das pilhas. O mais surpreendente é que os respondentes acreditam que os catalisadores do grupo PGM Podem ser substituídos. / Assessing future energy systems is of major importance for providing information on potential environmental awareness of the some life cycle stage of innovative technologies, for determining competitive advantages compared to conventional technologies and for developing scenarios of future. The main objective of this work is to provide a contribution for the evaluation of the environmental impact of fuel cells of low and media temperature, including all life cycles, and hydrogen production step, using the Delphi methodology. This work introduces and characterizes several types of fuel cells, which are more researched in the last years and presents several life cycles analysis for the fuel cells, their manufacture, operation and waste after the lifetime. The Delphi research is presented, with the first and second round results, the questionnaire and the methods descriptions adopted in this study. The Delphi Methodology is detailed in this work detailing the entrance data, the philosophy to be used in this study of the future scenes, as well as, the statistical treatment to be used for evaluation of the final results. A questionnaire was constructed and a respondents team participated in the research. Initially they received the questionnaire in the first round. In the next round they received again the questionnaire together with the responses obtained in the first stage. At the end, the study it was verified it there was an increase of consensus and an influence of the most qualified respondents on the other respondents. The results showed that the respondents believe in reducing the environmental impact of fuel cells. The most surprising in the research is that the respondents believe that the group\'s PGM catalysts can be replaced.

A avaliação dos sistemas de fornecimento de energia para o futuro é da maior importância para se obter informações sobre o potencial de impacto ambiental dos vários estágios do ciclo de vida das tecnologias inovadoras, determinando as vantagens competitivas sobre as tecnologias convencionais e para o desenvolvimento de cenários futuros. Este trabalho apresenta e caracteriza os tipos de pilhas combustíveis de média e baixa temperatura mais pesquisadas e comercializadas nos últimos anos. Realiza-se também a apresentação da avaliação do impacto ambiental dos principais materiais utilizados nas pilhas a combustível, considerando as fases de fabricação, operação e disposição final após o término da vida útil. São apresentados vários dados de LCA (Life Cycle Assessment) efetuados para alguns tipos de pilhas. O trabalho efetuou uma contribuição ao estudo da avaliação de impacto ambiental das pilhas a combustível de média e baixa temperatura utilizando a metodologia Delphi. Foi construído um questionário e um banco de dados para formação do conjunto de respondentes que participaram da pesquisa. Eles receberam o questionário na primeira rodada e o responderam. Depois receberam novamente o questionário em conjunto com as respostas obtidas na primeira etapa, para nova rodada de respostas. Ao final o estudo verifica se ocorreu aumento de consenso e a influência dos respondentes mais qualificados sobre os menos qualificados. Os resultados mostraram que os respondentes acreditam numa redução do impacto ambiental das pilhas. O mais surpreendente é que os respondentes acreditam que os catalisadores do grupo PGM Podem ser substituídos. / Assessing future energy systems is of major importance for providing information on potential environmental awareness of the some life cycle stage of innovative technologies, for determining competitive advantages compared to conventional technologies and for developing scenarios of future. The main objective of this work is to provide a contribution for the evaluation of the environmental impact of fuel cells of low and media temperature, including all life cycles, and hydrogen production step, using the Delphi methodology. This work introduces and characterizes several types of fuel cells, which are more researched in the last years and presents several life cycles analysis for the fuel cells, their manufacture, operation and waste after the lifetime. The Delphi research is presented, with the first and second round results, the questionnaire and the methods descriptions adopted in this study. The Delphi Methodology is detailed in this work detailing the entrance data, the philosophy to be used in this study of the future scenes, as well as, the statistical treatment to be used for evaluation of the final results. A questionnaire was constructed and a respondents team participated in the research. Initially they received the questionnaire in the first round. In the next round they received again the questionnaire together with the responses obtained in the first stage. At the end, the study it was verified it there was an increase of consensus and an influence of the most qualified respondents on the other respondents. The results showed that the respondents believe in reducing the environmental impact of fuel cells. The most surprising in the research is that the respondents believe that the group\'s PGM catalysts can be replaced.

Submitted by Almir Azevedo (barbio1313@gmail.com) on 2017-12-07T16:15:32Z No. of bitstreams: 0 / Made available in DSpace on 2017-12-07T16:15:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-10 / A mão de obra no setor nuclear está envelhecendo e se aposentando. O fluxo de saída de pessoal é maior que o de entrada, gerando uma diferença que pode comprometer a operação de algumas instalações num futuro bem próximo. Nesta cenário, a Agência Internacional de Energia Atômica (AIEA) vem promovendo há alguns anos, debates e iniciativas que ajudem a minimizar esse impacto. Com o objetivo de apresentar o setor nuclear e despertar o interesse pela matéria, várias iniciativas são tomadas. Considerar as peculiaridades de fontes de energia, torna-se importante por traçar paralelos e esclarecer pontos específicos do assunto de maneiro que o indivíduo, após seu conhecimento, tenha condições de avaliar e criar uma visão mais realista sobre o tema, desmistificando e atualizando alguns conceitos sobre cada setor apresentado. Este trabalho apresenta algumas fontes que compõem a matriz energética brasileira, suas externalidades e as ferramentas de computação utilizadas na construção de um objeto de aprendizado voltado ao público infanto e juvenil. Desta forma se pretende atender ao pleito da AIEA em propagar conhecimentos de energia nuclear entre indivíduos ainda em formação, e que possa ainda cumprir a missão de derrubar mitos de maneiro responsável, e quem sabe despertar interesses naturais para o setor nuclear. Para isto, utiliza recursos de computação gráfica e realidade virtual na construção de um objeto de aprendizado que possa ser utilizado como ferramenta de educadores em sala de aula.

Tesi per compendi de publicacions. La consulta íntegra de la tesi, inclosos els articles no comunicats públicament per drets d'autor, es pot realitzar prèvia petició a l'Arxiu UPC / Recently, the emergence of lab-on-a-chip devices has seen in a variety of applications especially in clinical analys is and diagnostics. ln particular the lack of suitable microdevices for separation of plasma from whole blood is a barrier to achieve a reliable lab on a chip (LOC) blood test. In order to address this issue, a novel self-driven high throughput blood plasma separator microchip is introduced as a first step to a miniaturized blood analys is. PDMS (Polydim ethylsiloxane) is utilized as the base material for the microdevice fabrication to ens ure the biocompatibility, the disposability (single-use to avoid contamination) and the low cost ofthe system for the mass-manufacturing. One of the characteristic features ofthe presented m icrodevice is that it needs to work just by capillary pressure eliminating the need of external sources. The requested capillary pressure to drive blood through the microdevice is derived via PDMS modification byanalyzing different surfactants, which are mixed with pre-cured PDMS to achieve a stable hydrophilic character. Furthermore, a diamond microchannel integrated micropillar (dMIMP) pump with high throughput and with a resistance flow 35.5% lower than a circular based micropillar pump (cMIMP) has been developed. For this purpose, the pressure drop and flow resistance of a lam inar flow through low aspect ratio MIMPs with different shapes and geometrical parameters are experim entally, numerically and analytically determined. In order to characterize the fabricated microcapillarypumps in PDMS, a novel and simple fabrication technique is introduced to overcome the PDMS deform ation under high-pressure operation. The presented fabrication technique combines the use of stiff PDMS (1 0:2, the ratio between polymer base and cross liking agent) and a thin coating layer of the UV curable thiolene resin as supporter (Norland Optical Adhesive 63) on the fabricated PDMS microchannel. Finally, using all the achieved results in the material property and microcapillary pump design in the last steps, a novel selfd riven high throughput microfluid ic chip for blood plasma separation is designed and fabricated. The presented microdevice can successfu lly separate more than 0.11JL of plasma from a whole human fresh blood drop (51JL) without the need of external forces with high efficiency(more than 90%) and reasonable time (3 to 5 minutes). The achieved plasma volume (0.1 IJL) in 10 1Jm-depth collected channels ofthe presented self-driven microdevice paves the path to integrate this microfluidic circuit in a portable medical point-of-care-testing (POCT) for doing different blood analysis. / Recientemente, la aparición de dispositivos de laboratorio en un chip (Lab on a chip) ha generado una gran variedad de nuevas aplicaciones especialmente en análisis clínicos y diagnóstico. En particular, la falta de micro dispositivos adecuados para la separación del plasma de la sangre es una barrera para lograr un dispositivo portátil que pueda realizar una análisis de sangre. Con el fin de abordar esta cuestión, un microsistema auto impulsado que pueda obtener una cantidad importante de plasma sanguíneo de una gota de sangre seria un primer paso para un análisis de sangre miniaturizado. En esta tesis se utiliza PDMS (Polydimethylsiloxane ) como material de base para la fabricación del microdispositivo debido a su biocompatibilidad y su bajo coste. Uno de los rasgos característicos del dispositivo presentado es que trabaja solo con presión capilar que elimina la necesidad de fuentes externas. La presión capilar solicitada para conducir sangre a través del microdispositivo se obtiene mediante la modificación del PDMS mediante diferentes agentes tensioactivos, que se mezclan con PDMS pre-curado para lograr un carácter hidrófilo estable. El proceso de filtración se basará en una estructura de columnas con baja relación de aspecto. Estás estructuras se han analizado numéricamente, analíticamente y experimentalmente, para obtener un diseño con baja resistencia al flujo. En concreto, se ha diseñado un conjunto de microcolumnas base diamante (dMIMP) que se utilizará como bomba de alto rendimiento y baja resistencia al flujo (35.5 % menor que una bomba microcolumnas circulares (cMIMP)). Para realizar esta caracterización se ha desarrollado un sistema de fabricación que permita caracterizar las estructruas de PDMS, a alta presión sin que se deformen. Por último, se ha utilizado el PDMS modificado y la bomba capilar optimizada para realizar un diseño de microfiltro de plasma sanguíneo de alto rendimiento. El microdispositivo presentado puede separar más de 0.11microL de plasma de una gota de sangre fresca humana (5microL) sin la necesidad de fuerzas externas con una alta eficiencia (más del 90%) y un tiempo razonable (de 3 a 5 minutos). El volumen de plasma obtenido es suficiente para implementar diferentes tipos de test sanguíneo y por tant representa el primer paso hacia la creación de un punto de atención portàtil (POC, point of care).

La determinación de las tensiones a las que están sometidos los engranajes es una parte importante del proceso de cálculo de la capacidad de carga de una transmisión de engranajes, que se realiza habitualmente mediante métodos analíticos, semianalíticos o numéricos. Para que estos métodos proporcionen resultados precisos, es importante que se apliquen bajo escenarios tan realistas como sea posible. No obstante, las limitaciones de estos métodos, que pueden estar impuestas por sus hipótesis de cálculo o por su coste computacional, hacen que en ocasiones se desprecien algunos efectos que pueden tener cierta influencia sobre el estado tensional de la transmisión. Entre estos efectos, uno de especial relevancia es la desalineación de los engranajes producida por la deformación bajo carga de los ejes que los soportan. En este trabajo, se han estudiado las limitaciones de los métodos analíticos, semianalíticos y numéricos utilizados habitualmente para la determinación del estado tensional de transmisiones de engranajes de ejes paralelos, y se han propuesto nuevos métodos de cálculo, o modificaciones de los existentes, para vencer estas limitaciones y tener en cuenta el comportamiento elástico de los ejes en el cálculo de las tensiones a las que están sometidos los engranajes. Posteriormente, haciendo uso de los métodos propuestos, se ha propuesto un nuevo procedimiento de modificación de la geometría de los dientes de los engranajes, que permite compensar los efectos negativos de la desalineación del engrane.

Normally, there are in use certain technologies of reduction of noise named passive, in the cancellation of the noise produced by industrial machinery. These technologies can be applied directly on the source (use of absorbers, mufflers and closings), in the way of transmission (as isolations, acoustic barriers, materials of absorption and acoustic sounders), or in the recipient (as the acoustic conditioning of locals or ear protective ). In this thesis, there is applied a technology different from that of passive type, named active control of noise, centring his use on the field of the industrial machinery.The active control is based on the attenuation or elimination of a acoustic wave by destructive interference. Though nowadays the active control of noise is in use commercial in some applications like air ducts, elements of auditory personal protection, cabins of planes ¿, it is occasionally used in industrial buildings, where the machines are in the habit of issuing serious and strongly tonal noise, what a priori, they are the suitable conditions for the utilization of the above mentioned control. The problem is that the industrial machinery places inside industrial buildings of big dimensions and therefore of high modal density. Normally passive technologies can be applied encasing totally the source with panels of absorbent and insulating material. But to low frequencies, to encase is not synonymous of reducing the level of noise in the exterior, since these materials in the range of low frequencies have very under performance of attenuation and enclosed to the resonance frequencies of the capsule is possible to come to increase the sonorous level in the exterior. If the active control is realized there is not obtained a global reduction (in the whole space) but punctually near the microphones of control. This doctoral thesis tries to demonstrate that, introducing a noise source in a suitable capsule is achieved to diminish the modal density of his acoustic field, and therefore, it is possible to obtain the global cancellation for active control of the noise generated by this one in an enclosure of big dimensions, where of direct form it would be totally impossible to realize it for other means. There has carried out the theoretical model of the acoustic field produced in an enclosure for an encased source and has been validated by means of level measurements of sonorous pressure in the interior and exterior of the encapsulamiento for a loudspeaker. With these equations the active control and his parameters have been studied for an ideal cancellation depending on different situations and applications. There have been realized tests of active control of an electrical encased engine, the results have been analyzed them comparing to the obtained ones with the theoretical model, a loudspeaker or the own engine without encasing, so much inside the capsule as in the exterior enclosure, corroborating the kindness of the active capsule. There has been realized a practical application of this theory in the cancellation by active control of the noise of a ventilator of a personal computer.

Departing from an emerging technology such as the spread tow thin-ply technology, in which the ply thickness can be significantly reduced, the overall purpose of this thesis is motivated by the industry need to better understand the potential benefits of thin-ply laminates in terms of delamination resistance and to propose predictive tools for their design. The first part of the thesis enhance the understanding of the damage mechanisms observed at the free-edge of thin-ply based laminate under different loading directions. The second part evaluates the capability of two current design approaches to predict the onset of free-edge delamination. Finally, a design procedure is established to search for the quasi-isotropic laminate with optimal delamination resistance under off-axis loads. The results of this thesis demonstrate the advantages of thin plies in delaying, or even suppressing the onset of damage mechanisms over standard ply laminates. / Partint d'una tecnologia emergent com la dispersió de fibres (en anglès, spread tow technology), en la qual el gruix de capa pot ser significativament reduït, la motivació per dur a terme aquesta tesi prové del desig, per part de la indústria, de comprendre millor els beneficis dels laminats de capes primes en termes de resistència a la delaminació i proposar eines de predicció per al seu disseny. La primera part d'aquesta tesi té com objectiu entendre millor els mecanismes de dany a la vora lliure d'un laminat de capes primes sotmès a diferents direccions de càrrega. La segona part consisteix en avaluar dos procediments actuals per la predicció de la delaminació per efecte de vora. Finalment, es proposa una metodologia per obtenir laminats quasi-isòtrops amb una resistència a la delaminació òptima. Els resultats d'aquesta tesi demostren els avantatges de l'ús de capes primes per retardar, o fins i tot suprimir la iniciació dels mecanismes de dany respecte els laminats de capes estàndard.

Los metamateriales (MTMs) representan una interesante área de investigación emergente que promete lograr un importante progreso tecnológico y científico en diversas áreas como las telecomunicaciones, la microelectrónica, radar, e imágenes médicas. La cantidad de artículos dedicados a la investigación en esta área (MTMs) se mantiene en pleno crecimiento en la actualidad. Las estructuras MTMs pueden sostener una fuerte resonancia electromagnética con longitudes de onda electricamente pequeñas y por lo tanto son potencialmente aplicables para la miniaturización de los componentes. La miniaturización, optimización del rendimiento del dispositivo mediante la eliminación de frecuencias espurias, y la posibilidad de controlar el ancho de banda del filtro para amplios márgenes de frecuencias es un reto para los presentes y futuros dispositivos de comunicación. Esta tesis se focaliza en el estudio de ambos temas (MTMs y miniaturización) centrándose en las nuevas estrategias para la miniaturización de componentes basados en MTMs. Desde la aparición de estos, los resonadores dieléctricos (DR) son un nuevo tipo de MTMs distinguidos por sus pequeñas pérdidas, así como su fácil combinación con estructuras externas; son la elección adecuada para todo proceso de desarrollo. La principal ventaja de utilizar una alta constante dieléctrica como DR es miniaturizar el tamaño del filtro. El tamaño del filtro de DR es considerablemente menor que la dimensión de la guía de ondas de otros filtros que operan a la misma frecuencia. Dada una constante dieléctrica, tanto la frecuencia de resonancia como el factor de calidad Q se definen a partir de las dimensiones del resonador dieléctrico. Cuanto mayor es la constante dieléctrica, menor es el espacio en el que se concentran los campos, y por lo tanto las dimensiones necesarias para trabajar a una frecuencia de operación definida quedan reducidas. Con el objetivo de miniaturizar las dimensiones del dispositivo, en este trabajo se propone un nuevo diseño para un filtro rechaza banda basado en la alta constante dieléctrica que proporciona una fina capa de pasta epoxy (TFDR) como material DRs excitado a través de una línea microstrip. Además, se propone un filtro pasa banda diseñado en base a los resonadores dieléctricos incrustados (EDR), esto constituye un nuevo enfoque en el campo de los resonadores miniaturizados adaptado a los metamateriales, logrando evitar la degradación del factor Q inherente al coeficiente de acoplamiento basado en partículas eléctricamente pequeñas. En esta tesis se propone también un nuevo filtro pasa de banda basado en resonadores de anillo dividido (SRRs), que es uno de los bloques de construcción MTMs más popular hoy en día. Los filtros de paso de banda basados en este concepto resultan prometedores para las aplicaciones donde la miniaturización y la compatibilidad con la tecnología de ondas planares milimétricas son los requisitos críticos del diseño. Además, para mayor miniaturización, tecnología DR de incrustado es reportada. Otro enfoque para la reducción de tamaño se basa en modificar el resonador tradicional para generar modos adicionales, los cuales hacen que el resonador se comporte como un resonador multimodal. Por último, se propone un filtro compacto paso banda de banda ultra ancha (UWB) utilizando un resonador de anillo abierto conectado a tierra empleado como un resonador multimodal (MMR). Esta propuesta permite utilizar cinco resonancias para producir un ancho de banda fraccional del 128% dentro de la banda ultra ancha. Para demostrar y validar la funcionalidad de los diseños, todos los dispositivos propuestos se han implementado y fabricado, con una excelente concordancia entre las simulaciones y las medidas experimentales. A través de estos métodos ha quedado demostrado que los modelos de sus circuitos equivalentes proporcionan una descripción precisa del comportamiento de las estructuras. En este trabajo se ha conseguido relacionar una relación directa entre las dimensiones físicas del dispositivo y su modelo equivalente eléctrico en forma de circuito. / Metamaterials (MTMs) represent an exciting emerging research area that promises to bring about important technological and scientific advancement in various areas such as telecommunication, radar, microelectronic, and medical imaging. The amount of research on this MTMs area has grown extremely quickly in this time. MTM structure are able to sustain strong sub-wavelength electromagnetic resonance and thus potentially applicable for component miniaturization. Miniaturization, optimization of device performance through elimination of spurious frequencies, and possibility to control filter bandwidth over wide margins are challenges of present and future communication devices. This thesis is focused on the study of both interesting subject (MTMs and miniaturization) which is new miniaturization strategies for MTMs component. Since, the dielectric resonators (DR) are new type of MTMs distinguished by small dissipative losses as well as convenient conjugation with external structures; they are suitable choice for development process. The primary advantage in using a high dielectric constant as a DR is to miniaturize the filter size. The size of DR filter is considerably smaller than the dimension of waveguide filters operate at the same frequency. For a given dielectric constant, both resonant frequency and Q-factor are defined according to the dielectric resonator dimensions. That, the higher the dielectric constant, the smaller the space within which the fields are concentrated, the lower the dimension at a defined frequency. To obtain the required compact sizes new stop-band filter is proposed in this work based on number of thick film high dielectric constant epoxy paste (TFDR) as DRs which excited with a microstrip line. In addition, a band-pass filter is proposed based on embedded dielectric resonators (EDR) constitutes a new approach to the miniaturized resonators suitable for metamaterials design without the Q degradation inherent to the coupling coefficient based on sub-wavelength particles. Also this thesis is proposed a new band-pass filter based on split ring resonators (SRRs), which is a one of the popular MTMs building blocks today. The band-pass filters based on this concept can be very promising for the applications where miniaturization and compatibility with planar millimeter wave technology are the important issues. Also, for further miniaturization, embedded DR technology is reported. Another approach for size reduction is modifying the traditional resonator to generate additional modes, which make the resonator to behave as a multimode resonator. Finally a compact ultra-wide band-pass (UWB) band-pass filter using grounded open ring resonator as a multimode resonator (MMR) is proposed. The approach allows using five resonances to produce a 128% fractional bandwidth into the ultra-wide band. A general theoretic framework has been established using transmission matrix description of the filter constituent components. To demonstrate and validate designs functionality, all the proposed devices are implemented and fabricated, which a good agreement between simulations and measurement are obtained. Through these methods it is demonstrated that their equivalent circuit models provide an accurate description of the considered structures. Indeed, a clear relationship between their equivalents circuit model and the layout physical dimensions were found.

The energy efficiency assessment of high-pressure pneumatic circuits is the aim of this dissertation. From a historical perspective the past and cur- rent activities with regards to the energy saving conservation in pneumatic technology were examined, and it could be concluded that high pressure pneumatic circuits have been repeatedly used for years in several industrial applications but to date no studies on that specific field are known. After a systematic review of studies concerning energy saving in pneumatic applications, a complete dynamic model for a high-pressure air blowing machine, employed in the production of plastic bottles, was developed. A synthetic version of the real pneumatic system was considered and consisted of a valve manifold, two tanks, one that simulated the mould cavity where the plastic preform is commonly blown and the other, was intended to recycle air. The one-dimensional models were derived for the pneumatic valve, pipes and vessels. The dynamic modelling of the valve took into account the flow non-linearities through the various geometrical restrictions as well as the pressure and temperature evolution at the inner chambers. Because of the existence of flow discontinuities in the pipes, different solving methods were applied, taking as starting point the Method of Characteristics and continued delving into finite volume methods such as Riemann-solver-based schemes. On the experimental phase a single blowing station unit was designed and built up. The pressure and temperature characteristics at different positions of the pneumatic circuit were measured in detail. In addition, the fluid flow through the valve manifold could be characterised by the sonic conductance and critical pressure ratio, which were determined by the isothermal discharge method. Effort was also expended to study the behaviour of the pressure waves generated along the tubes. The pressure wave propagation was computationally charted, with the intention of assessing how this parameter affected the recycling process. The examination of the experimental results proved the efficiency of the re- cycling process and demonstrated to be in close agreement with the mathematical model. The parameters governing the maximum amount of air to be recycled at each working cycle were identified, and the influence of the pipe geometry was discussed. Finally the author provides recommendations for future research and makes suggestions regarding the valve design to enhance the efficiency of the system. / El objetivo de esta investigación es evaluar la eficiencia energética de los circuitos neumáticos que trabajan con presiones muy superiores a las que habitualmente se emplean en la mayoría de aplicaciones industriales. Un análisis exhaustivo de como el ahorro energético se ha tratado a lo largo de las últimas décadas permite concluir que a pesar de que existen numerosos estudios que revisan las diferentes metodologías empleadas tanto en el reciclaje como en la reducción del consumo de aire comprimido, ninguno presta atención a las aplicaciones que representan el objeto de este estudio. La revisión de las patentes publicadas en las últimas décadas pone de manifiesto la actividad creciente en el desarrollo de máquinas de soplado para botellas de plástico (PET). Las diferentes técnicas empleadas con la intención de reciclar el aire empleado en una de las fases de soplado indican la necesidad de un ahorro de energía. En base a este escenario, se desarrolló un modelo matemático que permite determinar la variación transitoria de los principales parámetros físicos que gobiernan el flujo de aire a través del circuito neumático utilizado en una máquina de soplado de aire a alta presión. El modelo reducido de dicho circuito consiste de un bloque de válvulas, dos tanques, uno que simula la cavidad del molde, donde la preforma de plástico se moldea mediante inyección por soplado y el otro, en el que se recicla el aire empleado en el soplado. Debido a la existencia de discontinuidades de flujo en las tuberías, se aplicaron diferentes métodos de resolución para las ecuaciones de Euler, tomando como punto de partida el Método de las Características y finalizando con métodos numéricos basados en esquemas del tipo Riemann-solver. Por otro lado el modelado matemático de la válvula tiene en cuenta las no linealidades del flujo a través de las diversas restricciones geométricas, así como la evolución de presión y temperatura en los volúmenes interiores de la misma. En la fase experimental, se diseñó y construyó una estación de soplado que permitía determinar las características de presión y temperatura en diferentes posiciones del circuito neumático. Esto permitió determinar el comportamiento de las ondas de presión generadas a lo largo de los tubos y su influencia el proceso de reciclaje. A sí mismo, se emplearon métodos alternativos (simple discharge method and isothermal discharge method) para caracterizar el flujo a través del bloque de válvulas. El examen de los resultados experimentales demostró la eficiencia del proceso de reciclaje y demostró estar en estrecho acuerdo con el modelo matemático. Se identificaron los parámetros que rigen la máxima cantidad de aire que puede reciclarse en cada ciclo de trabajo, y se examinó la influencia de la geometría de la tubería. Por último, el autor aporta recomendaciones para futuras investigaciones y hace sugerencias sobre el diseño de la válvula neumática para mejorar la eficiencia del sistema.

Aquesta tesi doctoral te com a objectiu fonamental la integració monolítica de microressonadors en una tecnologia comercial, AMS 0.35um, tot utilitzant les capes disponibles del procés tecnològic. Les estructures son alliberades en un procés post-CMOS consistint en un atac humit basat en una solució HF, sense la necessitat de utilitzar cap mascara ni cap procés fotolitografia.Per tal de dissenyar i modelitzar aquests ressonadors, un model electromecànic basat en la deflexió real dels ressonadors serà descrit permetent al dissenyador predir el màxim de corrent a la ressonància. A més a més, un conjunt d'equacions de disseny serà presentat per tots els dispositius fabricats.Al llarg d'aquesta tesi diferents aproximacions tecnològiques tot utilitzant les capes disponibles de la tecnologia estàndard per fabricar microressonadors seran introduïts i discutits. Des del punt de vista del disseny, reduir la distància del gap entre el ressonador i el elèctrode esdevé un dels paràmetres més rellevants que potenciaran la resposta elèctrica del dispositiu. Aleshores, les aproximacions tecnològiques estaran encaminades a reduir la distancia del gap tan com sigui possible. Per a les aproximacions tecnològiques més prometedores, limitacions basades en el col·lapse vertical en el procés de alliberament seran considerats per tal de evitar el disseny s'estructurés amb limitació en el seu funcionament.Una aproximació tecnològica basada en les capes del mòdul estàndard per a la fabricació de capacitats integrades, ha resultat en una de les aproximacions més prometedores per a la fabricació integrada de ressonadors MEMS en el rangs de freqüències VHF i UHF, aconseguint gaps laterals de 40nm. Dispositius exhibint freqüències en el rang VHF, amb factors de qualitat fins a 3000 a 290MHz, seran presentats, obtenint una figura de mèrit de Qxf=9.1011 Hz. A més a més, resultats preliminars en la caracterització d'un anell ressonant en mode acústic a 1GHz serà descrit. / This thesis is focused on the monolithic integration of microresonators in a commercial CMOS technology, AMS-0.35um, by using the standard layers of the process. The structures are released in a maskless post-CMOS process based on a wet hydrofluoric etchant. Those resonators will make the role of frequency selective devices replacing off-chip components of present front-end tranceivers communication systems relying on their reduced size, cost production and lower consumption. In order to design and modelize those microresonators, an electromechanical model based on the real deflection of flexural resonator will be described allowing the designer to predict the maximum current levels at resonance. In addition to that, a set of mechanical design equations will be presented for all fabricated devices. Along this report, different technological approaches using the available layers of the standard technology for fabricating microresonators will be introduced and discussed. From the design point of view, reducing the gap distance between resonator and driver becomes one of the relevant parameters that will enhance the electrical response of the device. Then, the approaches will be focused on reducing gap distances as much as possible. For the most promising approaches, limitations based on the vertical stiction in the releasing process will be considered in order to avoid the design of structures with limited performance.A fabrication approach based on the layers of the standard capacitance module will stand out as the most promising approach for successfully fabricate integrated MEMS resonators in the VHF and UHF frequency range, as expenses of 40nm gap distances. Devices exhibiting frequencies in the VHF range, with high quality factors up to 3000 at 290MHz will be presented, giving a figure of merit of Qxf=9.1011Hz. Furthermore, preliminary results on the characterization of a ring bulk acoustic resonator at 1GHz will be described.