Les propriétés électroniques et d'autoassemblage de deux composés organiques, le DHTAP et le bis-pyrène, ont été étudiées par microscopie à effet tunnel (STM), sous ultra-vide et à basse température. Les propriétés optiques ont été étudiées par spectroscopie en cavité résonnante (CRD), également sous ultravide.La croissance du DHTAP a été étudiée sur différents métaux nobles. La croissance du bis-pyrène a été étudiée sur Au(111). Dans chaque cas, les conditions de température idéales pour la formation d’une première couche organisée ont été déterminées. Différents modèles sont proposés pour les structures observées en première couche. La formation de la seconde couche moléculaire à également été étudiée.L'évolution des propriétés optiques, étudié par CRD, du bis-pyrène déposé sur du verre borosilicate combinée aux informations obtenues par STM ont permit d’associer ces modifications aux interactions des moments dipolaires de transition des molécules de la première et de la seconde couche et on également permit de déterminer le mode de croissance.Finalement, la possibilité d’induire des modifications chimique de la molécule de DHTAP, intégrée dans une couche auto-assemblée, en utilisant le courant tunnel du STM a été observé. Il s’avère que la molécule de DHTAP intégrée en première couche peut subir une double déshydrogénation pour conduire à la formation d’un composé identifié comme étant le 5,7,12,14-tetraazapentacene (TAP). En seconde couche, la formation de deux radicaux, en plus du TAP, a été observé. La molécule de TAP présente un certain intérêt du fait qu’elle n’est pas synthétisable pas les méthodes conventionnelle de chimie organique. / Electronic and self-assembling properties of two organic compound, the DHTAP and the bis-pyrene, have been studied by the means of low temperature scanning tunnelling microscopy (STM) under ultrahigh vacuum conditions. Optical properties have been studied by cavity ring-down (CRD) spectroscopy, also under ultrahigh vacuum conditions.The growth of DHTAP has been studied on different metallic substrate. The growth of bis-pyrene has been studied on Au(111). In each case, the optimal temperature conditions for the formation of a well-ordered first monolayer have been determined. The formation of second monolayers has also been studied. The evolution of the optical properties, studied by CRD, of bis-pyrene deposited on borosilicate glass combined with information obtained from STM allow us to identify these modifications as interactions between transition dipole moments of molecules in the first and in the second layer, and also determine the growth mode.Finally, the possibility to induce chemical modification of DHTAP molecules embedded in an ordered monolayer using the tunnelling current of the STM has been studied. It appears that the molecule embedded in the first ML can be doubly dehydrogenated which leads to the formation of a compound identified as 5,7,12,14-tetraazapentacene (TAP). In the second layer, the formation of two radicals in addition to the TAP has been observed. The TAP molecule is interesting because of that it cannot be synthesized using common organic chemical methods.

Ce travail de thèse porte sur l’étude de l’effet du traitement par champs électriques pulsés (CEP) sur l’amélioration de la congélation des tissus végétaux. Pour l’ensemble de notre étude, nous avons démontré que l’effet des champs électriques pulsés est complexe. Le prétraitement entraîne une électroperméabilisation des membranes. Les analyses calorimétriques ont mis en évidence que l’électroperméabilisation conduit à une augmentation de la teneur en eau liée. Les transferts de matière entre les milieux intra et extracellulaires sont intensifiés. Cela conduit à une modification dynamique de la composition des deux compartiments au cours de la congélation. En effet, les essais réalisés sur le cryo-pressage assisté par CEP démontrent que les températures de fusion sont plus basses et que le jus récupéré est beaucoup plus concentré. Il a été constaté que le temps de congélation d’un échantillon soumis préalablement à un prétraitement par champs électriques pulsés est sensiblement plus court que celui d’un échantillon sans prétraitement. D’autre part, l’électroperméabilisation facilite les transferts de matière avec le milieu extérieur. Le prétraitement par CEP accélère notamment l’imprégnation des tissus végétaux par des cryoprotectants, l’évaporation de l’eau libre et la sublimation de l’eau congelée. Finalement, le prétraitement par champs électriques pulsés induit des modifications de la structure des échantillons, de leur composition et influence favorablement les transferts couplés de masse et d’énergie. / This work is focused on the study of the effects of pulsed electric fields (PEF) on the improvement of plant tissues freezing. These studies have demonstrated that the effects of the PEF are rather complex. The PEF treatment results in membrane electro-permeabilization. Calorimetric analyses showed that the electro-permeabilization leads to an increase in bound water content. It also results in acceleration of mass transfer processes between intra- and extracellular parts of a tissue. The dynamic modification of the composition of these two parts during the freezing was observed. Experimental tests using the PEF-assisted cryo-pressing demonstrated that the melting temperatures were lower and that the extracted juice was much more concentrated as compared to untreated tissues. Moreover, the PEF-treatment allowed significant decreasing of freezing time. Furthermore, the electro-permeabilization facilitates the mass transfer with the external medium. The PEF treatment accelerates the impregnation of plant tissues by cryoprotectants, evaporation of free water and sublimation of frozen water. Finally, the treatment by PEF induces changes in the structure of the samples, their composition and positively influences both the mass and energy transfers.

The present research aims to develop a novel technique for creation of composite riot helmet shells with reinforcing fibre continuity for better protection against low velocity impacts. In this research an innovative, simple and effective method of making a single-piece continuously textile reinforced helmet shell by vacuum bagging has been established and discussed. This technique also includes the development of solid collapsible moulding apparatus from non-woven fibres. Angle-interlock fabric due to its good mouldability, low shear rigidity and ease of production is used in this research. Several wrinkle-free single- piece composite helmet shells have been manufactured. Low-velocity impact test on the continuously reinforced helmet shells has been carried out. For this purpose an in-house helmet shell testing facility has been developed. Test rig has been designed in such a way that the impact test can be carried out at different locations at the riot helmet shell. Low-velocity impact test has been successfully conducted on the developed test rig. The practical experimentation and analysis revealed that the helmet shell performance against impact is dependent on the impact location. The helmet shell top surface has better impact protection as compared to helmet shell side and back location. Moreover, the helmet shell side is the most at risk location for the wearer. Finite Element models were created and simulated in Abaqus software to investigate the impact performance of single-piece helmet shells at different impact locations. Models parts have been designed in Rhinoceros software. Simulated results are validated by the experimental result which shows that the helmet top position is the safest position against an impact when it is compared to helmet back and helmet side positions.

My dissertation deals with the progress of consumer society in the 60th of 20th century in the Czechoslovakia. At the beginning of my work i try to theory of consumer society, everydayness and the free time in czechoslovak society. My aim is equipment of electric apparatus in the families and their importance for women's work in households. Especially I reply the questions, where and how the apparatus were sold, how was the quality of them and how much apparatus saved women's jobs. I analyse the availability of those apparatus for consumers/users. I compare amount, prices and design of home appliances in Czechoslovakia and abroad. My dissertation is based on the fact that in 60th of 20th century was very big increase of refrigerators, automatic washing machines, irons, hoovers, hairdryers, televisions and next smaller home appliances. I compare this growth with countries of Western Europe. My dissertation is based on studium of specialized monographs, articles and studies of czech and english provenance. But I also use the unpublished sources of institucional and personal characters (Archive of the National Technical Museum, the National Museum Archive

Le contexte du réchauffement climatique entraîne un développement des technologies CSP (Concentrated Solar Power). La réduction des coûts de production de ces technologies passe par une amélioration de la durabilité et de l'efficacité des composants des centrales solaires. Les températures de fonctionnement élevées du CSP (250-600°C) nécessitent d'employer des absorbeurs spectralement sélectifs afin de limiter les pertes par radiation. Cette thèse propose une architecture originale d'absorbeurs sélectifs stables à haute température sous air en combinant un dépôt de TiAlN en couches minces avec un réseau de diffraction. L'ajout d'une texturation de surface augmente l'absorption solaire du dépôt par un effet d'absorption et de gradient des indices optiques effectifs conduisant à une augmentation du rendement photothermique de l'absorbeur. Dans ce mémoire, la modélisation du comportement optique des absorbeurs texturés, les méthodes de fabrication du réseau de diffraction ainsi que le dépôt des couches minces par PVD et PECVD seront abordés et les mesures expérimentales seront comparées aux modélisations. L'analyse des absorbeurs texturés fabriqués confirme un gain de rendement photothermique pouvant atteindre +3% ainsi qu'une stabilité thermique remarquable à 500°C sous air jusqu'à 300 h de recuit / The global warming context reinforces the development of CSP technologies. Cost reduction of CSP requires the improvement of component durability and efficiency. The solar absorbers should be spectrally selective since the high working temperatures of CSP plants increase the radiative thermal losses. This thesis proposes an original, spectrally selective absorber structure combining TiAlN based coatings and diffractive gratings. The surface texturing provided by the diffractive gratings improves the solar absorption of the thin coating by an effective optical index gradation effect leading toincreased photothermal efficiency. In this thesis, the modeling of the textured absorber’s optical behavior, fabrication methods of diffractive gratings, as well as layer deposition by PVD/PECVD will be discussed. Experimental measurements will be compared to the theoretical modelling. The experimental analysis of textured absorbers confirms the increase of photothermal efficiency by almost 3%, as well as a good thermal stability at 500°C in air for 300 hours of annealing

Le multipactor est un phénomène parasite qui se produit dans les dispositifs où l'on transmet une onde hyperfréquence sous vide tels que les tubes électroniques à vide, les cavités résonnantes pour accélérateurs de particules et les circuits micro-ondes à bord des satellites. Il consiste en une avalanche d'électrons mis en mouvement par un champ hyperfréquence. La simulation du multipactor est cruciale dans tout design de structure HF sous vide. Les géométries complexes 3D d'objets imposent de posséder des outils de simulations tridimensionnels pour prédire ce phénomène. Le premier travail de cette thèse a consisté à valider un logiciel de simulation 3D du multipactor, Musicc3D, à la fois par le calcul et l'expérimentation. Une étude théorique à une dimension ainsi qu'une simulation 2D éprouvée ont été réalisées et les résultats du logiciel Musicc3D ont été favorablement confrontés à leurs résultats. Des règles de définition du maillage 3D ont été établies pour un bon fonctionnement de la simulation 3D. Toujours pour valider la simulation, l'ensemble des cavités accélératrices construites par l'IPNO ces dernières années a été simulé et favorablement comparé aux observations de barrières de multipactor quand elles existaient. Dans le but d'exploiter les prédictions de la simulation 3D, mais aussi de la valider et enfin d'être capable de qualifier différents matériaux et/ou états de surfaces, une cavité résonnante équipée de mesures dédiées au multipactor a été construite. Les premiers résultats obtenus avec cette cavité ont été favorablement comparés à la simulation. / Multipacting is a parasitic phenomenon and extremely detrimental in devices where there is a ultra high frequency wave transmitted in a vacuum environment such as vacuum electron tubes, resonant cavities for particle accelerators and microwave circuits on board of satellites. It consists of an avalanche of electrons put in motion by a microwave field. Multipacting simulation is crucial in any HF structure design. The complex 3D geometrics obligates to have three-dimensional simulation tools to predict this phenomenon. The first study in this thesis consisted in validating a 3D simulation software of Multipacting, Musicc3D, by calculation and experimentation. A theoretical study with one dimension and a a tested 2D simulation were carried out and the results of the software Musicc3D were favorably confronted to their results. 3D grid definition rules were established for the proper working of the 3D simulation. Also to validate the simulation, the whole of the park of accelerating cavities built by the IPNO these last years was simulated and favorably compared with the observations of barriers of Multipacting when they existed. With an aim of exploiting the predictions of the 3D simulation, but also to validate it and finally be able to qualify various materials and/or state of surfaces, a resonant cavity equipped with measurements dedicated for Multipacting was built. The first results obtained with this cavity were favorably compared to the simulation.

The direct epitaxial growth of multilayer BN by atomic layer deposition is of critical significance forfo two-dimensional device applications. X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) demonstrate layer-by-layer BN epitaxy on two different substrates. One substrate was a monolayer of RuO2(110) formed on a Ru(0001) substrate, the other was an atomically clean Ni(111) single crystal. Growth was accomplished atomic layer deposition (ALD) cycles of BCl3/NH3 at 600 K substrate temperature and subsequent annealing in ultrahigh vacuum (UHV). This yielded stoichiometric BN layers, and an average BN film thickness linearly proportional to the number of BCl3/NH3 cycles. The BN(0001)/RuO2(110) interface had negligible charge transfer or band bending as indicated by XPS and LEED data indicate a 30° rotation between the coincident BN and oxide lattices. The atomic layer epitaxy of BN on an oxide surface suggests new routes to the direct growth and integration of graphene and BN with industrially important substrates, including Si(100). XPS and LEED indicated epitaxial deposition of h-BN(0001) on the Ni(111) single crystal by ALD, and subsequent epitaxially aligned graphene was deposited by chemical vapor deposition (CVD) of ethylene at 1000 K. Direct multilayer, in situ growth of h-BN on magnetic substrates such as Ni is important for spintronic device applications. Solid-state electrolytes (SSEs) are of significant interest for their promise as lithium-ion conducting materials but are prone to degradation due to lithium carbonate formation on the surface upon exposure to atmosphere, adversely impacting Li ion conduction. In situ XPS monitored changes in the composition of the SSE Li garnet (Li6.5La3Zr1.5Ta0.5O12, LLZTaO) upon annealing in UHV and upon Ar+ ion sputtering. Trends in core level spectra demonstrate that binding energy (BE) calibration of the Li 1s at 56.4 eV, yields a more consistent interpretation of results than the more commonly used standard of the adventitious C 1s at 284.8 eV. Annealing one ambient-exposed sample to >1000 K in UHV effectively reduced surface carbonate and oxygen, leaving significant amounts of carbon in lower oxidation states. A second ambient-exposed sample was subjected to 3 keV Ar+ ion sputtering at 500 K in UHV, which eliminated all surface carbon, and reduced the O 1s intensity and BE. These methods present alternative approaches to lithium carbonate removal than heating or polishing in inert atmospheres and are compatible with fundamental surface science studies. In particular, the data show that sputtering at mildly elevated temperatures yields facile elimination of carbonate and other forms of surface carbon. This is in contrast to annealing in either UHV or in noble gas environments, which result in carbonate reduction, but with significant remnant coverages of other forms of carbon.

Nutri Fruti es un plan de negocio dedicado a la producción y comercialización de frutas exóticas envasadas al vacío, con la finalidad de satisfacer las necesidades de los clientes, quienes buscan consumir productos con un alto valor nutricional y que sean fáciles de preparar. Está orientado al nivel socioeconómico A y B entre hombre y mujeres entre 25 a 39 años que residan en los distritos de Lima Moderna. La propuesta de valor es ofrecer un producto diferenciado y premium que permita ahorrar tiempo a los clientes en su día a día, con frutas exóticas nutritivas en trozos congelados. El proyecto está orientado sobre supuestos de un crecimiento porcentual del 30% en el segundo año, 25% en el tercer y cuarto año; y 20% en el quinto año, fundamentado con fuentes sobre el crecimiento del rubro alimentario y la diferenciación de nuestros productos. Se tendrá una inversión inicial de 102, 497 soles del cual el 50% será financiamiento de accionistas y el otro 50% será financiado por terceros. Asimismo, representa un escenario positivo para el retorno de la inversión de los accionistas con un COK de 10.63% y el costo del financiamiento del proyecto WACC de 13.74% para cubrir sus obligaciones. El proyecto es viable y rentable, ya que el VAN es de S/. 318,439 soles y una TIR de 116.49% con un tiempo de recuperación de la inversión de 2 años y por cada sol que se invierta se obtendrá una ganancia de 6.21 soles. / Nutri Fruti is a business plan dedicated to the production and commercialization of exotic fruits vacuum packed, to satisfy the needs of customers, who seek to consume products with a high nutritional value and that are easy to prepare. It is oriented to the socioeconomic level A and B between men and women between 25 and 39 years old who reside in the districts of Modern Lima. The value proposition is to offer a differentiated and premium product that allows customers to save time in their day-to-day lives, with nutritious exotic fruits in frozen pieces. The project is oriented on assumptions of a percentage growth of 30% in the second year, 25% in the third and fourth year; and 20% in the fifth year, based on sources on the growth of the food industry and the differentiation of our products. There will be an initial investment of 102,497 soles of which 50% will be financing from shareholders and the other 50% will be financed by third parties. Likewise, it represents a positive scenario for the return on investment of shareholders with a COK of 10.63% and the cost of financing the WACC project of 13.74% to cover their obligations. The project is viable and profitable, since the NPV is S /. 318,439 soles and an IRR of 116.49% with a recovery time of the investment of 2 years and for each sol that is invested, a profit of 6.21 soles will be obtained. / Trabajo de investigación

This diploma thesis deals with a basic description of dynamic and condenser microphone, its performance regarding polar patterns and a type of mechanical construction. It also describes a principle of operation of a triode. The thesis deals with selecting of a suitable type of microprocessor to control microphone preamplifier functions. Last part contains a power supply and microphone preamplifier circuits design using a semiconductor and vacuum tube technology.

The beginning of this thesis contains an overview of properties of the insulators, and description of insulators that were used for in depth research of surface breakdown in vacuum. Furthermore, this work focuses on mechanisms of an electric breakdown initiation at the interface of the solid insulator and surrounding low pressure gas. Multiple methods for measurements of dielectric strength are examined. The experimental part describes the measurements performed in the vacuum chamber. The results of these measurements are then analysed. In conclusion, used insulators are compared and suggestions for further work are given.