Récupérer l'énergie mécanique ambiante est une alternative prometteuse afin d'assurer l'autonomie énergétique d'appareils nomades. Le développement des générateurs électrostatiques souples reste toutefois à ce jour anecdotique du fait des hautes tensions de polarisation employées, de la nécessité de grandes déformations mécaniques mais aussi de l'utilisation de matériaux peu conventionnels et mal caractérisés. Le but de cette thèse est d'apporter des avancées scientifiques et des solutions aux verrous technologiques précités. Tout d'abord, une caractérisation rigoureuse des propriétés électriques et mécaniques de deux matériaux communément utilisés pour ces applications (acrylate VHB 4910 et silicone Polypower) nous a donné accès aux propriétés physiques dans un fonctionnement réel de ces polymères : influence de la précontrainte, de la nature des électrodes... Ces données ont permis d'élaborer des lois analytiques fiables que nous avons ensuite insérées dans un modèle thermodynamique permettant de définir avec précision les puissances et densités d'énergie récupérables pour ces générateurs. Des pistes d'amélioration des matériaux utilisés dans les applications générateurs peuvent être dégagées de notre modèle. Le second verrou à lever concerne la source haute tension de polarisation nécessaire à ces générateurs électrostatiques. Pour cela, nous avons proposé une solution innovante couplant l'élastomère diélectrique à un électret. Différentes configurations de générateurs hybrides dans des géométries 2D et 3D ont été évaluées. Enfin, nous avons réalisé un prototype qui a délivré une puissance de l'ordre de 35µW sachant qu'une optimisation de ce prototype est réalisable et que des puissances récupérées de plusieurs centaines de µW sont tout à fait réalistes. / Scavenging mechanical ambient energy is a promising solution to ensure the autonomy of wearable transducers. Nevertheless, the development of soft electrostatic generator (DEG) is up to now slow down due to the use of high bias voltage, high strain and innovative mischaracterized materials. The aim of this Ph-D thesis is to propose innovative solutions to these technological barriers. Firstly, a complete characterization of the electrical and mechanical properties of two commonly used dielectric polymer (acrylate VHB 4910 and silicone Polypower) has revealed the true physical properties of these polymers and especially the influence of the pre-stress and the nature of the electrode used. Thanks to these data, reliable analytic laws have been proposed and inserted into our thermodynamic model in order to predict the output power and scavenged energy density for the DEG. Moreover, our model allow us to propose improvements for the materials used in these applications. The second challenge is to propose an alternative to the high bias voltage needed for these soft generators. We have proposed an innovative solution combining an electret and a dielectric elastomer. Various configurations of hybrid generators in 2D or 3D geometry have been modelled and evaluated. Finally, a prototype has been designed allowing scavenging 35µW. With an appropriate optimization of our prototype, hundreds of µW can be scavenged.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Barium Titanate (BaTiO3 BT) based Ceramic materials have a wide industrial application as Multilayer Ceramic Capacitors (MLCCs) mainly due to its high dielectric constant and good capacitance stability with the temperature change, however this material also presents some limitations, for example, oxidation of low cost electrodes. Several ways of BT modifications have been proposed in Literature, as example, the use of different synthesis methods and the doping with different ions. Therefore, the present work had as objectives the synthesis, sintering and electrical characterization of the BaTiO3 and Ba0.77Ca0.23TiO3 (Barium Calcium Titanate) ceramics. The Sol Gel Proteic method was used to powder synthesis, in this method, coconut water is employed as polymeric agent instead of the conventional alcoxide precursors. The characterization was done using the differential thermal analysis, thermogravimetry, x-ray powder diffraction, scanning electron microscopy and impedance spectroscopy techniques. Both, the calcined powders at 1100 °C and the sintered ceramics at 1350 °C presented single crystalline phase, with good microstructural homogeneity and relative density higher than 90%. The sintered ceramics presented a dielectric constant value at room temperature of 1200 (BT) and 680 (BCT), and dielectric loss of 4,8% (BT) and 1,8% (BCT). Besides, the BCT ceramics presented a Curie temperature on average 14 °C above that observed in Literature. Finally, the activation energies of the conductive process of the grain an grain boundary regions were evaluated following two distinct methods using: i) the Brick-layer model; and ii) the average relaxation frequency of each ceramic region, grain and grain boundary. The obtained values by the two methods are in accordance with them and suggest that the dominant conduction mechanism occurs by oxygen vacancy diffusion created still during the sintering process. / Materiais cerâmicos a base de titanato de bário (BaTiO3 BT Barium Titanate ) possuem uma larga aplicação industrial como Capacitores Cerâmicos Multicamadas (MLCCs Multi layers ceramic capacitors ) devido, principalmente, a sua alta constante dielétrica e boa estabilidade da capacitância com a variação da temperatura, porém esse material apresenta também algumas limitações, como por exemplo, a oxidação de eletrodos de baixo custo. Diversas modificações no BT têm sido sugeridas na literatura, como a utilização de diferentes métodos de síntese e a dopagem com diferentes íons. Dessa forma, o presente trabalho objetivou a síntese, a sinterização e a caracterização elétrica de cerâmicas de BaTiO3 e Ba0.77Ca0.23TiO3 (Titanato de Bário e Cálcio BCT Barium Calcium Titanate ). Para a síntese dos pós foi utilizado o método sol-gel proteico, neste método, a água de coco é utilizada como agente polimérico, ao invés dos alcóxidos convencionais. Para a caracterização das amostras foram utilizadas as técnicas de análise térmica diferencial, termogravimetria, difração de raios X, microscopia eletrônica de varredura e espectroscopia de impedância. Os pós calcinados a 1100°C bem como as cerâmicas sinterizadas a 1350°C e apresentaram fase cristalina única, com boa homogeneidade microestrutural e densidade relativa superior a 90%. O valor da constante dielétrica à temperatura ambiente foi de 1200 para o BT e 680 para o BCT com perda dielétrica de 4,8% e 1,8%, respectivamente. Além disso, as cerâmicas de BCT apresentaram uma temperatura de Curie em média 14 °C acima dos valores observados na Literatura. Por ultimo, as energias de ativação dos processos condutivos nas regiões de grão e de contorno de grão foram obtidas seguindo dois procedimentos distintos: i) utilizando o modelo de brick-layer; e ii) utilizando a frequência de relaxação média de cada região da cerâmica, grão e contorno de grão. Os valores obtidos pelos dois métodos concordaram entre si e sugerem que o mecanismo de condução dominante ocorre por vacâncias de O2- formadas ainda durante o processo de sinterização.

[EN] Sustainability is nowadays an investment for the future of any economic activity. The current situation of crisis has had an adverse impact in most industries, including the agri-food sector. However, this industry has been relatively the least affected when compared with other industrial sectors. This is mainly attributed to the fact that food products continue to be basic for consumers despite the economic downturn. Therefore, the agri-food sector is a key element in the European economy and can play a crucial role in the achievement of the objectives set in the EU's strategy for 2020: ensuring a sustainable framework of growth of a more competitive economy. The European agri-food industry has focused on energy efficiency and on reducing greenhouse gases emissions, along with better management of their resources as a way to improve its industrial competitiveness. In this sense, the search for solutions to transform the by-products generated in high value-added ingredients, is a priority. In this context, the juice industry, as fundamental sub-sector within the food sector, and large waste generator, must exploit the opportunity to transform their by-products into useful and profitable products for society. This transformation presents some difficulties which impede the profitability of the process. These difficulties are associated with the by-product, such as its compositional variability and its seasonality, and current techniques of transformation as the high energy cost in dehydration processes. This thesis represents an innovative and sustainable solution for overcoming the disadvantages associated with the high costs of stabilization, turning this by-products into high value-added ingredients, from both, nutritional and technological, points of view. The aim is to develop a microwave coupled with hot air drying technique allowing maximizing profits by using the following strategy: reducing time and operational costs, producing a new ingredient rich in dietary fiber, with interesting technological properties for the development of healthy foods, studying the proposed comprehensive process and analyzing the new generated by-products. The methodological approach of the thesis been focused, on the one hand, on studying phenomena that govern the internal transport of water and energy through the orange peel during its dehydration applying thermodynamics. On the other hand, the energy consumption of the drying process, the technological and sensory properties of the fiber obtained and its potential use as a fat substitute have been compared with the conventional hot air drying method. Finally, the integrated process, including both the combined drying technique and the pretreatments needed for colour and bitter compounds extraction, is proposed as a new route of valorization, in which the new by-products obtained, polyphenols and carotenoid rich extracts, are analysed. This study has analyzed the microwave coupled with hot air process, developing tools that allow the adequate upscaling of the drying operation by adapting it to the best standards of quality of the final product. A monitoring system that ensures these standards has been designed. The quality and the energy consumption of the dietary fiber production process has been improved. The properties associated with its inclusion in food matrices have been optimized. An innovative and sustainable process for the stabilization of industrial by-products and for their further conversion into dietary fiber and other bioactive compounds, applying microwave coupled with hot air drying, has been developed. / [ES] La sostenibilidad es una de las apuestas de futuro en cualquier actividad económica. La situación de crisis ha tenido un impacto adverso en la mayoría de las industrias, incluyendo las de ámbito agroalimentario. Sin embargo, ésta ha sido relativamente la menos afectada cuando se compara con otros sectores industriales. Esto se atribuye al hecho de que los productos alimenticios continúan siendo básicos para los consumidores a pesar de la desaceleración económica. Por lo tanto, esta industria es un pilar fundamental en la economía europea y puede jugar un papel crucial en la consecución de los objetivos marcados en la Estrategia de la UE para 2020: asegurar un marco sostenible de crecimiento de una economía más competitiva. La industria agroalimentaria europea ha apostado por la eficiencia energética y la reducción de emisiones de gases invernadero, junto con una mejor gestión de sus recursos como vía para la mejora de su competitividad industrial. La búsqueda de soluciones para transformar los subproductos generados en ingredientes de alto valor añadido, es una de las prioridades. En este contexto, la industria productora de zumos, como subsector fundamental dentro del sector alimentario, y gran generador de residuos, tiene la oportunidad de transformar sus subproductos en productos útiles y rentables para la sociedad. Esta transformación presenta algunas dificultades que impiden la rentabilidad del proceso. Estas dificultades están asociadas al subproducto, como su variabilidad composicional o su estacionalidad, y a las técnicas actuales de transformación como el elevado coste energético en procesos de deshidratación. Esta tesis se plantea como una solución innovadora y sostenible para, más allá de superar los inconvenientes asociados a los altos costes de estabilización, transformar este subproducto en un ingrediente de alto valor añadido, tanto nutricional como tecnológico. Para ello se propone desarrollar una técnica de secado combinado por aire caliente y microondas que permita maximizar beneficios mediante la siguiente estrategia: reducir el tiempo y el coste energético de la operación, produciendo un nuevo ingrediente rico en fibra dietética con propiedades tecnológicas de interés para el desarrollo de alimentos más saludables, estudiando el proceso integral propuesto y analizando los nuevos subproductos generados. El enfoque metodológico de la tesis ha estado dirigido, por una parte, a estudiar los fenómenos que gobiernan el transporte interno de agua y energía a través de la piel de naranja durante su deshidratación, aplicando termodinámica. Por otra parte, el consumo energético del proceso de secado, las propiedades tecnológicas y sensoriales de la fibra obtenida y su potencial uso como ingrediente sustituto de grasa, se han comparado con el método de secado convencional por aire caliente. Finalmente, el proceso integrado, incluyendo tanto el secado combinado como las etapas previas de extracción de color y compuestos amargos, se propone como una nueva ruta de valorización, en la que se analizan posibles subproductos de interés tales como extractos ricos en polifenoles y carotenoides. En este estudio se ha analizado el proceso combinado de secado con aire caliente y microondas, desarrollando herramientas que permiten dimensionar adecuadamente la operación de secado adaptándola a los estándares óptimos de calidad del producto final. Se ha diseñado un sistema de monitorización que asegure dichos estándares. Se ha mejorado el proceso de obtención de fibra alimentaria respecto a su calidad y a su gasto energético. Se han optimizado las propiedades asociadas a su inclusión en matrices alimentarias. Se ha desarrollado un proceso innovador y sostenible para la estabilización de subproductos vegetales de origen industrial y para su posterior conversión en fibra dietética y otros compuestos bioactivos, aplicando la tecnología de secado por aire caliente y / [CAT] La sostenibilitat és una de les apostes de futur en qualsevol activitat econòmica. L'actual situació de crisi ha tingut un impacte advers en la majoria de les indústries, incloent les d'àmbit agroalimentari. No obstant això, la indústria agroalimentària ha sigut relativament la menys afectada quan es compara amb altres sectors industrials. Açò s'atribuïx principalment al fet de que els productes alimentaris continuen sent bàsics per als consumidors a pesar de la desacceleració econòmica. Per tant, esta indústria és un pilar fonamental en l'economia europea i pot jugar un paper crucial en la consecució dels objectius marcats en l'Estratègia de la UE per a 2020: assegurar un marc sostenible de creixement d'una economia més competitiva. La indústria agroalimentària europea ha apostat per l'eficiència energètica i la reducció d'emissions de gasos d'efecte hivernacle, junt amb una millor gestió dels seus recursos com a via per a la millora del seu vaig competirtu En este sentit, la busca de solucions per a transformar els subproductes generats en ingredients d'alt valor afegit, és una de les prioritats. En este context, la indústria productora de sucs, com subsector fonamental dins del sector alimentari, i gran generador de residus, té el deure i l'oportunitat de transformar els seus subproductes en productes útils i rendibles per a la societat. Esta transformació presenta algunes dificultats que impedixen la rendibilitat del procés. Estes dificultats estan associades al subproducte, com la seua variabilitat composicional o la seua estacionalitat, i a les tècniques actuals de transformació com l'elevat cost energètic en processos de deshidratació. Esta tesi es planteja com una solució innovadora i sostenible per a, més enllà de superar els inconvenients associats als alts costos d'estabilització, transformar este subproducte en un ingredient d'alt valor afegit, tant nutricional com tecnològic. Per a això es proposa desenvolupar una tècnica de'assecat combinat per aire calent i microones que permeta maximitzar beneficis per mitjà de l'estratègia següent: reduir el temps i el cost energètic de l'operació, produint un nou ingredient ric en fibra dietètica amb propietats tecnològiques d'interés per al desenvolupament d'aliments més saludables, estudiant el procés integral proposat i analitzant els nous subproductes generats. L'enfocament metodològic de la tesi ha estat dirigit, d'una banda, a estudiar els fenòmens que governen el transport intern d'aigua i energia a través de la pell de taronja durant la seua deshidratació, aplicant termodinàmica. D'altra banda, el consum energètic del procés de d'assecat, les propietats tecnològiques i sensorials de la fibra obtinguda i el seu potencial ús com a ingredient substitut de greix, s'han comparat amb el mètode d'assecat convencional per aire calent. Finalment, el procés integrat, incloent tant l'assecat combinat com les etapes prèvies d'extracció de color i compostos amargs, es proposa com una nova ruta de valoració, en la que s'analitzen possibles subproductes d'interés com ara extractes rics en polifenoles i carotenoides. En este estudi s'ha analitzat el procés combinat d'assecat amb aire calent i microones, desenvolupant ferramentes que permeten dimensionar adequadament l'operació d'assecat adaptant-la als estàndards òptims de qualitat del producte final. S'ha dissenyat un sistema de monitorització que assegure els dits estàndards. S'ha millorat el procés d'obtenció de fibra alimentaria respecte a la seua qualitat i al seu consum energètic. S'han optimitzat les propietats associades a la seua inclusió en matrius alimentàries. S'ha desenvolupat un procés innovador i sostenible per a l'estabilització de subproductes vegetals d'origen industrial i per a la seua posterior conversió en fibra dietètica i altres compostos bioactius, aplicant la tecnologia d'assecat por aire calent i microones. / Talens Vila, C. (2015). DESARROLLO DE TÉCNICAS COMBINADAS DE SECADO CON AIRE CALIENTE Y MICROONDAS EN LA PRODUCCIÓN DE FIBRA ALIMENTARIA A PARTIR DE SUBPRODUCTOS CÍTRICOS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/54114 / TESIS

Neste trabalho, investigou-se capacitores MOS fabricados sobre superfícies irregulares contendo formas retangulares periódicas com 100 nm de altura, obtidas a partir de corrosão por plasma localizadas. Os óxidos de porta com 4,5 nm de espessura foram crescidos em ambientes ultrapuros de O2 ou pirogênico a fim de comparar a uniformidade de cobertura sobre os degraus verticais dos perfis retangulares. Foi mostrado que a oxidação pirogênica ou convencional na temperatura de 850 ºC permite obter óxidos de porta sobre degraus com altura de 100nm com baixa corrente de fuga e alto campo de ruptura. Esse comportamento pode ser interpretado como óxidos de porta perfeitamente amoldados sobre os degraus de 100nm de altura. O impacto deste resultado é agora a possibilidade de implementar óxidos de porta para transistores de porta envolvente e FinFETs. / In this work, it was investigated MOS capacitors fabricated onto periodic rectangular shapes, 100 nm in height, obtained by localized plasma etching onto silicon wafer surfaces. 4.5-nm gate oxide growth was performed in ultrapure dry O2 or pyrogenic environments in order to compare the coverage uniformity at the step edges of rectangular shapes defined onto the silicon surfaces. It was shown that pyrogenic and conventional oxidation at 850 ºC allows one to obtain gate oxides on 100nm-stepped silicon surfaces with low leakage current and high dielectric breakdown field. This behavior can be understood as highly conformal gate oxides over silicon steps with height of 100 nm. The impact of this result is now the feasibility of implementing gate oxides for surrounding gate transistors (SGT\'s) and FinFETs.

Ces travaux de thèse consistent à élaborer des nanocomposites Polyaniline/hexaferrite pour l’absorption des micro-ondes. L’idée principale est la mise en œuvre de matériaux composites à base de polymères conducteurs intrinsèques telle la Polyaniline que nous avons dopée avec différents types d’acides (HCl, CSA, NSA et TSA…) et l’hexaferrite de baryum de type magnétoplombite (M) stœchiométrique ou substitué. Au niveau de l’hexaferrite de baryum, la substitution du Fe3+ s’est faite par les ions Al3+, Bi3+, Cr3+ et Mn3+.L’hexaferrite de baryum et les hexaferrites substitués par les différents ions cités ci-dessus ont été synthétisés par voie hydrothermale dynamique en faisant varier divers paramètres au cours de la synthèse (pH, température, temps, rapport [OH-]/[NO3-]…).L’élaboration des composites Polyaniline/hexaferrite (pur ou substitués) a été effectuée par polymérisation oxydative en utilisant plusieurs techniques de synthèse : la polymérisation chimique en solution (en tenant compte de la nature de l’acide utilisé) avec ou sans agitation (Aqueous-Based Polymerization with or without stirring) et la polymérisation oxydative par voie solide (Solid-Based Polymerization). L’optimisation de ces différentes techniques de synthèse après caractérisations physicochimiques (DRX, FTIR, ATG, MEB, EDX), diélectriques (ε’, ε’’, σdc) et magnétiques (Mr, Ms, Hc, Tc, µ’, µ’’) des échantillons, a montré que la polymérisation par voie solide se trouve la méthode la plus facile, économique et respectueuse de l’environnement. Elle est aussi adaptée à la production du composite Pani/BaFe12O19 avec de bonnes propriétés structurales, physiques et magnétiques. L’étude de la substitution du Fe3+ dans le BaFe12O19 par Al3+, Bi3+, Cr3+ et Mn3+ a montré une forte dépendance des propriétés structurales et magnétiques avec la distribution de ces ions dans la maille cristalline hexagonale. En effet, les ions Al3+, Cr3+ et Mn3+ ont une tendance à occuper les sites tétraédriques, alors que le Bi3+ occupe les sites octaédriques. Une augmentation de Hc associée à la taille des cristallites a été observée pour les particules substituées avec l'Al et le Cr alors qu’une modification de l'anisotropie magnetocristalline (fort terme d'ordre supérieur) a été mise en évidence pour les substitutions Bi et Mn, dû à leur grand rayon ionique. L’incorporation des hexaferrites substitués dans la Polyaniline pour obtenir des composites Pani/BaMeFe11O19, où Me = Al, Bi, Cr et Mn, révèle une variation des propriétés électromagnétiques dans la gamme de fréquences allant de 1 à 18 GHz. En effet, ces variations sont dues à la formation de dipôles entre l’ion de substitution et les cations O2- dans le ferrite qui sont responsables de la résonance ferromagnétique, de l'anisotropie magnétocristalline et des interactions avec la matrice polymérique. Le composite Pani/BaFe12O19 présente des absorptions dans la bande X qui se déplacent vers la bande Ku avec la substitution du fer confirmant / This thesis deals with the formulation of Polyaniline/hexaferrite nanocomposite for absorbing electromagnetic waves. The main idea is the process of composite materials based on polymers intrinsic conductors such as polyaniline that we doped with different types of acids (HCl, CSA, NSA, and ... TSA) and barium hexaferrite with magnetoplumbite structure with or without substitution according to desired stoichiometries. In the barium hexaferrite, the substitution of Fe 3+ is made by Al3+, Bi3+, Cr3+ and Mn3+ ions.The barium hexaferrite and its substitutions by different ions mentioned above were synthesized dynamic hydrothermal method by varying various parameters during the synthesis (pH, temperature, time, ratio [OH-]/[NO3-] ...).The elaboration of polyaniline/hexaferrite composite (pure or substituted) was carried out by oxidative polymerization using various synthesis techniques: Aqueous-Based Polymerisation with or without agitation (taking into account the nature of the acid used) (ABP) and Solid-Based Polymerization (SBP). The optimization of these various synthesis techniques after physicochemical (XRD, FTIR, TGA, SEM, EDX), dielectric (ε ', ε' ', σdc) and magnetic (Mr, Ms, Hc, Tc, µ', µ'') characterizations of the samples showed that the solid route is the easiest method, economical and environmentally friendly. It is also suitable for the production of composite Pani/BaFe12O19 with good structural, physical and magnetic properties.The study of the substitution of Fe 3+ in the BaFe12O19 by Al3+, Bi3+, Cr3+ and Mn3+ showed a strong dependence of the structural and magnetic properties with the distribution of these ions in the hexagonal crystal lattice. In fact, Al3+, Cr3+ and Mn3+ ions tend to occupy the tetrahedral sites, while the Bi3+ favoured the octahedral sites. An increase in Hc associated with the small crystallite size observed for particles substituted with Al and Cr and the enhancement magnetocristalline anisotropy (strong higher order term) for Bi and Mn due to their high ionic radius.The incorporation of the substituted hexaferrite in the polyaniline to obtain Pani/BaMeFe11O19 composite, where Me = Al, Bi, Cr and Mn, reveals a variation in electromagnetic properties in the frequency range from 1 to 18 GHz. In fact, these variations are due to the formation of dipoles between the substituting ion and surrounding O2- cations in the ferrite which are responsible for the ferromagnetic resonance, the magnetocrystalline anisotropy and the exchange interaction with the polymer. The composite Pani/BaFe12O19 shows absorption bands at the X-band that shift to the Ku-band with the substitution of iron, confirming the potential of these materials for microwave applications.

This study experimentally investigated the effect of hydrophobic and hydrophilic surfaces characteristics on nucleate boiling heat transfer performance for the application of direct immersion cooling of electronics. A dielectric liquid, HFE – 7100 was used as the working fluid in the saturated boiling tests. Twelve types of 1-cm2 copper heater samples, simulating high heat flux components, featured reference smooth copper surface, fully and patterned hydrophobic surface and fully and patterned hydrophilic surfaces. Hydrophobic samples were prepared by applying a thin Teflon coating following photolithography techniques, while the hydrophilic TiO2 thin films were made through a two step approach involving layer by layer self assembly and liquid phase deposition processes. Patterned surfaces had circular dots with sizes between 40 – 250 μm. Based on additional data, both hydrophobic and hydrophilic surfaces improved nucleate boiling performance that is evaluated in terms of boiling incipience, heat transfer coefficient and critical heat flux (CHF) level. The best results, considering the smooth copper surface as the reference, were achieved by the surfaces that have a mixture of hydrophobic/hydrophilic coatings, providing: (a) early transition to boiling regime and with eliminated temperature overshoot phenomena at boiling incipience, (b) up to 58.5% higher heat transfer coefficients, and (c) up to 47.4% higher CHF levels. The studied enhanced surfaces therefore demonstrated a practical surface modification method for heat transfer enhancement in immersion cooling applications.

Bearing in mind environmental concerns and global trends in ecology, biodegradable polyesters have gained enormous attention as alternative to non-biodegradable, commercial polymers used mainly in packaging industry contributing to the worldwide environment pollution. However, substitution of conventional polymers with biodegradable polyesters is limited due to their inferior mechanical and barrier properties, which can be improved by the introduction of relatively small content of non-toxic nanofillers. Nevertheless, environmental pollution is not only affected by material itself, but also manufacturing and processing sector in terms of energy sustainability. In case of the latter, low energetic processes are nowadays preferential. Thus, using microwave irradiation as the more efficient energy source, which can lead to shortening of process time, has become currently investigated subject. In this thesis, microwave-assisted in-situ synthesis of biodegradable nanocomposites based on polycaprolactone and non-toxic clay nanoparticles (layered double hydroxides) was studied and described in detail in four subsections (4.1-4.4). The first subsection (4.1) describes one-pot synthesis of Mg2+ /Al3+ layered double hydroxides functionalized with highly microwave-absorbing ionic liquids. In order to improve...

The thesis deals with linearly polarized dielectric rectangular resonator antenna (DRA) operating in the basic mode TEy11 and higher order mode TEy131 at f0 = 10GHz surrounded by an electromagnetic band gap structure (EBG). The dielectric resonator antennas, the EBG structure were designed and a method of integration of both components was developed. The simulated results show a significant improvement of the radiation pattern in the E-plane radiation pattern (narrower main beam, lower level of side lobes, higher directivity) in comparison to a conventional DRA. This was verified by the TEy11 measurement.

This document includes methods of testing and measuring of the protective layers used in solar panels with crystallic solar cells. The main emphasis here is placed on the degradation of these materials due to exposure to strong electric field. Main point of diploma thesis is evovle an experimental workplace for electric aging of dielectric materials and monitor changes of material properties. Final knowledges are then analysed with the climate degradation tests. Tested samples were prepared in cooperation with Solartec s.r.o.

This thesis deals with the dielectric relaxation spectroscopy applied to samples of an epoxy slip filled by grounded mica with granularity of 40 m. The changes of dielectric properties were investigated depending on the fulfillment of grounded mica, temperature, the relative air humidity, and the frequency between 100 Hz and 1MHz.