Dans ce mémoire, on étudie la désintégration d’un faux vide, c’est-à-dire un vide qui est un minimum relatif d’un potentiel scalaire par effet tunnel. Des défauts topologiques en 1+1 dimension, appelés kinks, apparaissent lorsque le potentiel possède un minimum qui brise spontanément une symétrie discrète. En 3+1 dimensions, ces kinks deviennent des murs de domaine. Ils apparaissent par exemple dans les matériaux magnétiques en matière condensée. Un modèle à deux champs scalaires couplés sera étudié ainsi que les solutions aux équations du mouvement qui en découlent. Ce faisant, on analysera comment l’existence et l’énergie des solutions statiques dépend des paramètres du modèle. Un balayage numérique de l’espace des paramètres révèle que les solutions stables se trouvent entre les zones de dissociation, des régions dans l’espace des paramètres où les solutions stables n’existent plus. Le comportement des solutions instables dans les zones de dissociation peut être très différent selon la zone de dissociation dans laquelle une solution se trouve. Le potentiel consiste, dans un premier temps, en un polynôme d’ordre six, auquel on y rajoute, dans un deuxième temps, un polynôme quartique multiplié par un terme de couplage, et est choisi tel que les extrémités du kink soient à des faux vides distincts. Le taux de désintégration a été estimé par une approximation semi-classique pour montrer l’impact des défauts topologiques sur la stabilité du faux vide. Le projet consiste à déterminer les conditions qui permettent aux kinks de catalyser la désintégration du faux vide. Il appert qu’on a trouvé une expression pour déterminer la densité critique de kinks et qu’on comprend ce qui se passe avec la plupart des termes. / In this thesis, we study the tunneling decay of the false vacuum, that is, a vacuum that is a relative minimum of a scalar potential. Topological defects in 1+1 dimension, called kinks, appear when the potential possesses a minimum that spontaneously breaks a discrete symmetry. In 3+1 dimensions, these kinks become domain walls. For instance, they appear in magnetic materials in condensed matter. A model with two coupled scalar fields will be studied, as well as the solutions to the equations of motion that arise from it. We will then analyze how the energy of the static solutions depend on the parameters of the model. A numerical survey of parameter space reveals that the stable solutions are located between dissociation zones, areas in parameter space where stable solutions no longer exist. The behavior of the unstable solutions in the dissociation zones can be very different depending on which dissociation zone a solution is found near the dissociation zone. The potential first consists in a sixth-order polynomial, to which is added a quartic polynomial multiplied by a coupling term, and is chosen such that the extremities of the kink are at distinct false vacua. The decay rate has been estimated by a semiclassical approximation to show the impact of topological defects on the stability of the false vacuum. The project consists in determining the conditions that allow the kinks to catalyze false vacuum decay. It appears that we found an expression for the critical kink density and that we understand what happens with most terms.

Penning trap mass spectrometry (PTMS) can be used to test the Standard Model (SM) and to answer the questions related to the origin and abundance of the elements in the universe. There are several facilities worldwide specialized in PTMS and some of them can measure the masses of isotopes with half-lives in the range of milliseconds. TRIUMF’s ion trap for atomic and nuclear science (TITAN) is one such facility. In mass measurement the precision is linearly proportional to the charge state of the ion of interest. To increase the charge state, ions are charge-bred using an electron beam ion trap (EBIT) at TITAN. However, the charge breeding process introduces an energy spread among the ions which adversely affects the precision of the mass measurement. To overcome this problem a cooler Penning trap (CPET) was designed, assembled and is now being tested off-line. This thesis presents the first systematic test results of CPET. We also present the result of the first Penning trap mass measurement of the isotope 24Al, which is five times more precise than the previous atomic mass evaluation (AME2012) value. The precise and accurate mass of 24Al is important for both astrophysics and for test of the standard model (SM). The resonance energy (E_r) calculated for the 23Mg(p,gamma)24Al reaction using the ground state mass of 24Al reported in this thesis shows a 2s deviation from the direct measurement. On the other hand, tests of the SM by evaluating f_t values using isospin T = 1 nuclides have reached a high precision level. Effort is now shifting towards the T = 2 nuclides, which are far from stability compared to their T = 1 counterparts. For this reason, the ground state masses of T = 2 nuclides and of their decay products are required to be known with high precision. 24Al is the daughter of one such nucleus, 24Si. The ground state mass of 24Al reported in this thesis will be useful to test the SM. / October 2016

The goal of Master's Thesis is an identification of life cycle costs of vacuum cleaners. Next point is an analysis of these life cycle cost by using value analysis. The theoretical part is focused on definitions of Life Cycle Costing (LCC) and Value Analysis (VA). The practical part, which is fundamental, contains identification of life cycle cost of selected vacuum cleaners, life cycle costing of selected vacuum cleaners and their value analysis. Result of this Master's Thesis is an interpretation of the results and the suggestion of steps for consumers and producers of vacuum cleaners.

Denna studie har utförts på Calamo AB som arbetar med elektropolering och betning av rostfritt stål. Efter ytbehandlingssteget krävs sköljning av godset för att avlägsna kemikalierester vilket medför att stora mängder surt sköljvatten uppstår. Idag används våtkemisk fällningsanläggning för att rena sköljvattnet. Det befintliga reningsverket kräver flertalet tillsatser samtidigt som mängden slam som går till deponi är stor. Företaget vill utreda miljönyttan med att installera en vakuumindunstare för att ersätta det befintliga reningsverket som reningsmetod samt se över möjligheten att minska sin vattenförbrukning i samband med sköljning av gods för att bland annat kunna reducera storleken på indunstaren, minska belastningen på reningsstegen samt reducera mängden avfall. Studiens mål var att kartlägga uppkomsten av förorenat sköljvatten, identifiera potentiella vattenbesparande åtgärder och hur dessa åtgärder påverkar effektiviteten hos reningsanläggningarna. Samt visa hur installation av en vakuumindunstare förändrar företagets miljöpåverkan och utreda om det finns möjligheter att återanvända eller återvinna kemikalier och metaller från processen. Kartläggning och flödesmätningar av sköljvattenbehovet utfördes med hjälp av information av personal på Calamo samt en ultraljudsmätare. Vattenbesparande åtgärder, påverkan på reningsanläggning samt möjligheter till återvinning av kemikalier undersöktes genom litteraturstudie samt modellering i Excel. Utredningen av miljönyttan genom att ersätta befintligt reningsverk med vakuumindunstare utfördes med hjälp av LCA-värden hämtade från databasen SimaPro 8.0.4. Flera olika förslag på vattenbesparande åtgärder studerades och dessa gav en total vattenreduktion till reningsverket på mellan 5 - 81 % beroende på hur många samt vilka åtgärder som vidtogs. Enligt miljöberäkningarna genererar vakuumindunstaren 3 gånger högre utsläpp av koldioxidekvivalenter och 7 gånger större behov av icke förnyelsebar energi jämfört med det befintliga reningsverket. Genom att installera sprutskölj med motströmsteknik i stycke, sammankoppla befintliga sköljkar i avdelningarna betning, AVFKA samt automaten och installera sparsköljstank i alla avdelningar uppnås en reduktion av förorenat vatten till reningsstegen på 81%, vilket ytterligare kan optimeras genom installation av jonbytare, återanvändning av varmt vatten från renrum. Dessutom ökar föroreningshalten med 61% då dessa åtgärder vidtas vilket gynnar reningseffektiviteten i reningsanläggningarna och därav rekommenderas detta alternativ. Även kemikalieanvändningen och förluster av metalljoner reduceras avsevärt i processen genom användningen av sparskölj. Att installera vakuumindunstare rekommenderas inte på grund av dess stora energianvändning, dock kan andra resultat uppstå då andra LCA-värden används samt genom andra antaganden och hänsyn till kemikalie- och metallåtervinning istället för deponi. / This study has been carried out at Calamo AB, which works with electropolishing and pickling of stainless steel. After the surface treatment step, rinsing of the material is required to remove chemical residues, which results in large amounts of acid rinse water. Today, wet chemical precipitation plant is used to clean the rinse water. The existing treatment plant requires most additives, while the amount of sludge that goes to landfill is large. The company wants to investigate the environmental benefits of installing a vacuum evaporator to replace the existing sewage treatment plant as a purification method and to review the possibility of reducing its water consumption in connection with rinsing of goods in order to reduce the size of the evaporator, reduce the load on the purification steps and reduce the amount of waste. The aim of the study was to map the emergence of polluted rinse water, identify potential water-saving measures and how these measures affect the efficiency of the treatment plants. And show how the installation of a vacuum evaporator changes the company's environmental impact and investigate whether there are opportunities to reuse or recycle chemicals and metals from the process. Mapping and flow measurements of the rinse water requirement were performed using information from staff at Calamo and an ultrasonic meter. Water-saving measures, impact on treatment plant and opportunities for recycling of chemicals were investigated through literature study and modeling in Excel. The study of the environmental benefits by replacing existing treatment plants with vacuum evaporators was carried out using LCA values obtained from the database SimaPro 8.0.4. Several different proposals for water-saving measures were studied and these gave a total water reduction to the treatment plant of between 5 - 81% depending on how many and what measures were taken. According to the environmental calculations, the vacuum evaporator generates 3 times higher emissions of carbon dioxide equivalents and 7 times the need for non-renewable energy compared to the existing treatment plant. By installing spray rinse with countercurrent technology in one piece, interconnecting existing rinses in the cuttings departments, AVFKA as well as the dispenser and installing sparse rinse tank in all departments, a reduction of contaminated water to the purification steps of 81% is achieved, which can be further optimized by installation of ion exchangers, reuse of hot water from clean room. In addition, the pollutant content increases by 61% as these measures are taken, which favors the purification efficiency of the treatment plants and hence this option is recommended. The use of chemicals and losses of metal ions are also considerably reduced in the process through the use of savings rinses. Installing vacuum evaporators is not recommended due to its large energy use, however, other results may arise when other LCA values are used, as well as through other assumptions and considerations for chemical and metal recycling instead of landfill.

As perdas pós-colheita de alimentos hortícolas justificam a adoção de técnicas de conservação. Uma vez beneficiados, esses produtos permitem agregar valor à produção primária e se tornam de conveniência ao consumidor. Essa pesquisa teve como objetivo definir as metodologias do processamento mínimo de cenoura, pimentão e salada mista (batata e vagem), quanto ao tipo e intensidade de adoção das técnicas de barreiras e monitorar o processamento, via controle microbiológico, sensorial, físico-químico e nutricional. As hortaliças foram lavadas em água corrente, descascadas e cortadas com facas afiadas de aço inoxidável. Para a sanificação, foram imersas por 15 min em água refrigerada (± 7ºC) com 100 mg L-1 de cloro livre a pH ajustado para 7,0; a seguir foram centrifugadas a 550-900 G, por 5 min. As hortaliças foram acondicionadas, manualmente, em sacos plásticos de filme multicamada laminado, do tipo BOPP/PEBD (polipropileno biorientado/polietileno de baixa densidade). As embalagens foram fechadas em seladora modelo AP-500, marca Tec Maq, sob ar atmosférico, vácuo e atmosfera modificada (2% de O2, 10% CO2 e 88% de N2) e a seguir foram armazenados sob refrigeração a 1ºC ± 1ºC. A vitamina C não foi afetada em nenhum dos tratamentos nos três produtos. Os teores de b-caroteno mantiveram-se praticamente constantes em cenoura e salada mista; no pimentão, após a primeira semana de armazenamento, sofreram um decréscimo, permanecendo praticamente inalterados ao longo do armazenamento. Quanto à análise sensorial, os resultados para a cenoura e salada mista, foram satisfatórios até 21 dias de armazenamento para todos os tratamentos; exceto para o pimentão. Os três produtos obtiveram em todos os tratamentos, contagens para psicrotróficos variando de 10 2 a 10 5 UFC/g, 10 1 a 10 3 UFC/g e 10 3 a 10 6 UFC/g, respectivamente. Anaeróbios mesófilos e coliformes totais, foram constatados em pimentões minimamente processados. Porém, as baixas contagens obtidas, em todos os tratamentos, mostraram que a vida útil destes prolongou-se até o 14º dia de armazenamento. Para a cenoura e salada mista minimamente processadas, não foram constatados coliformes totais e fecais, anaeróbios mesófilos e Salmonella em nenhum dos tratamentos. / The postharvest losses of horticultural products justify the adoption of preservation techniques. Once these products are processed, they add value to the primary products and they become convenient to the consumer. This research had the purpose of defining the methodologies for minimal processing of carrot, green pepper and mixed salad of potato and string bean in relation to the type and intensity of adoption of the barrier techniques. In addition, it was our objective to monitor the processing, through by microbiological, sensory, physical-chemical and nutritional evaluation. The vegetables were washed in running water, peeled and cut with sharp stainless steel knives. For the sanitization they were submerged, for 15 min, in cold water (± 7ºC) with 100 mg L -1 of free chlorine at pH 7,0; next, they were centrifuged at 550-900 G, for 5 min. The product was hand packed in plastic bags BOPP/LDPE (biorientated polypropylene/low-density polyethylene). The packages were sealed under air, vacuum and modified atmosphere (2% O2, 10% CO2 and 88% N2) and stored under refrigeration at 1ºC±1ºC. The vitamin C content was not affected in any of the treatments. The values for b-carotene remained stable for carrot and mixed salad. For the green pepper, the values decreased after the first week of storage. In relation to the sensory analysis, carrot and mixed salad were considered satisfactory until 21 days of storage for all treatments; but for green pepper. In all treatments, counts for the three products ranged psychrotrophic ranging from 10 2 to 10 5 UFC g -1 , 10 1 to 10 3 UFC g -1 , 10 3 to 10 6 UFC g -1 , respectively. Anaerobic mesophiles and total coliforms were observed in minimally processed green peppers. However, the low count obtained in all treatments indicated a shelf life of 14 days. For the minimally processed carrot and mixed salad, no total or fecal coliforms, anaerobic mesophiles and Salmonella were observed in any of the treatments.

As observações astronômicas dos últimos 15 anos revelaram que o universo atualmente está expandindo aceleradamente. No contexto da relatividade geral se acredita que a energia escura, cujo melhor candidato é a densidade do vácuo ($\\Lambda/8\\pi G$), é o agente responsável por este estado acelerado. No entanto, o termo $\\Lambda$ tem duas sérias dificuldades: o problema da constante cosmológica e o problema da coincidência. Com o objetivo de aliviar o problema da constante cosmológica, muitos modelos adotam um termo $\\Lambda$ dinâmico, permitindo seu decrescimento ao longo de toda a história cósmica. Neste tipo de modelo, a equação de conservação do tensor momento energia total exige uma troca de energia entre a densidade do vácuo e as outras componentes energéticas do universo; o que também alivia o problema da coincidência. Neste trabalho discutimos diferentes consequências de um vácuo dinâmico no âmbito cosmológico e no processo de colapso gravitacional. Em particular, analisamos o caso em que a densidade do vácuo possui uma dinâmica não trivial com a escala de energia típica do universo, que depende monotonamente do parâmetro de Hubble, decrescendo ao longo de toda a história cósmica. Nos referiremos a este modelo como modelo deflacionário. Nesse contexto, utilizando os primeiros termos da expansão para a densidade do vácuo, sugerida pela teoria do grupo de renormalização em espaço-tempos curvos, propomos um novo cenário cosmológico baseado numa densidade do vácuo dinâmica. O cenário proposto é completo no sentido de que o mesmo vácuo é responsável pelas duas fases aceleradas do universo, conectadas por uma fase de radiação e um estágio de domínio da matéria. Neste cenário o universo plano é não singular, iniciando sua evolução a partir de um estágio do tipo de Sitter e, portanto, toda a história cósmica ocorre entre duas fases de Sitter limites. Este modelo não apresenta o problema de horizonte, e nele a nucleossíntese cosmológica ocorre como no modelo de Friedmann, e embora este modelo seja muito próximo do modelo $\\Lambda$CDM, o grande acúmulo de observações no estágio recente do universo permitirão que este poda ser testado. Adicionalmente, mostraremos que generalizações do modelo deflacionário incluindo curvatura espacial apresentam propriedades e vantagens similares. Usando observações de $H(z)$, da luminosidade de supernovas tipo Ia, da função de crescimento linear das perturbações escalares, e da posição do pico das oscilações acústicas de bárions conseguimos vincular um dos parâmetros do modelo. Por outro lado, analisando a física do universo primordial, assumindo um vácuo não perturbado, conseguimos limitar um segundo parâmetro fazendo uso do índice espectral das perturbações escalares. Com o objetivo de fazer uma análise mais completa do modelo no âmbito cosmológico, analisamos também as possíveis restrições oriundas da validade da segunda lei da termodinâmica em sua forma generalizada (GSLT). Para isto investigamos a evolução tanto da entropia associada ao horizonte aparente do universo, que é um horizonte atrapante devido a que o escalar de Ricci é positivo, como do seu conteúdo material. Motivados pela forma como a singularidade primordial do universo é evitada devido aos efeitos do decaimento do vácuo, incluímos no presente trabalho outra linha de desenvolvimento: a análise dos estágios finais do processo de colapso gravitacional em presença de uma densidade do vácuo dinâmica. Centraremos esta análise na determinação de modelos que possam ou não evitar a formação de um buraco negro. Mostraremos que modelos com um termo de vácuo proporcional à densidade de energia total do sistema, não podem evitar a formação de uma singularidade no estágio final do processo de colapso. Adicionalmente obteremos correções para a massa colapsada, para o tempo de formação do horizonte e para o tempo de colapso como função dos parâmetros do modelo e da curvatura espacial. Por último analisaremos a influência de uma densidade do vácuo capaz de dominar sobre as outras componentes no regime de altas energias, mostrando que este tipo de dinâmica na densidade do vácuo evita a formação de um estado final singular. / The astronomical observations of the last 15 years revealed that the universe is currently undergoing an expanding accelerating phase. In the general relativity context is believed that dark energy, whose best candidate is the vacuum energy density $ho_v \\equiv \\Lambda/8\\pi G$, is the fuel responsible for the present accelerating stage. However, the so-called $\\Lambda$-term has two serious drawnbacks, namely: the cosmological constant problem and the coincidence problem. In order to alleviate the cosmological constant problem, many models adopt a dynamical $\\Lambda$ term, thereby allowing its decreasing throughout the cosmic history. In this kind of model, the total energy conservation law defined in terms of the energy momentum tensor requires an energy exchange between the vacuum and the material components of the universe, which also contributes to alleviate the coincidence problem. In the present thesis we discuss different consequences of an interacting vacuum component both in the cosmological scenario as well as in the process of gravitational collapse. In particular, in the cosmological domain, we examine the case where the vacuum has a nontrivial dynamics dependent on a typical energy scale, the Hubble parameter, that decreases in the course of the cosmic history. We will refer to this model as deflationary model. In this context, by using a truncated expansion for the vacuum energy density, as suggested by the renormalization group theory in curved space-time, we propose a new cosmological scenario based on a dynamical $\\Lambda$-term. The proposed scenario is complete in the sense that the same vacuum is responsible for both accelerating phases of the universe, which are linked by two subsequent periods of radiation and non-relativistic matter domination. In this scenario the flat universe is nonsingular and starts its evolution from an asymptotic de Sitter stage, so that the cosmic story takes place between two extreme de Sitter phases. The model is free of the horizon problem as well as of the \"graceful exit\" problem plaguing many inflationary variants. In addition, the cosmological nucleosynthesis occurs as in the Friedmann model and the observations in the latest stages of the universe can potentially differentiate between the deflationary and the standard $\\Lambda$CDM model. The generalizations including spatial curvature are aslo discussed in detail. On the other hand, by using the late time tests like type Ia supernovae, the redshift dependence of the Hubble parameter, $H(z)$, the linear growth function of scalar perturbations, and the peak position of baryon acoustic oscillations we have constrained the basic parameters of the model. Conversely, analyzing the physics of the primordial universe and assuming that the vacuum is a smooth component, we have also constrained the spectral index of scalar density perturbations. In order to establish a more complete analysis of our cosmological scenario, we also discuss the possible constraints arising from the validity of the generalized second law of thermodynamics, that is, by including the horizon thermodynamics. Since the apparent horizon of the universe behaves like a trapped horizon because the Ricci scalar is positive, we investigate the evolution of both the entropy of the material components and the entropy associated to the horizon. Motivated by the avoidance of the Big-Bang singularity due to the decaying vacuum effects, we have explored another line of development: the analysis of the final stages of gravitational collapse process in the presence of a dynamic vacuum. This analysis focused on the determination of models able to prevent or not the formation of a black hole. In this connection, we shown that the presence of an interacting vacuum proportional to the total energy density of the system does not prevent the formation of a singularity in the final stages of the collapsing process. In addition, we obtain corrections for the collapsed mass, the horizon time formation and the collapsing time as a function of the free parameters and the spatial curvature of the models. Finally, we have also analyzed the influence of a vacuum contribution which dominates the other components into the high energy limit (due to the presence of higher orders terms in the contraction rate), and shown that for this kind of models the growth of the vacuum energy density prevents the formation of the singularity.

Les poudres laitières sont obtenues par concentration du produit liquide (membranes, évaporation sous vide) puis séchage du concentré. Contrairement au séchage par atomisation, peu de travaux ont été menés sur la concentration par évaporation sous vide. Pourtant, la maîtrise du schéma global de production des poudres gagnerait en une meilleure compréhension de cette opération réalisée dans des évaporateurs à flot tombant. Le présent travail vise à étudier comment améliorer les performances des évaporateurs ; il s’appuie sur deux facteurs limitants de l’opération : l’encrassement des surfaces d’échange et la viscosité maximale en sortie des évaporateurs. La contribution des différents constituants des produits à l’encrassement a été étudiée grâce à une méthodologie développée sur un évaporateur pilote.Les résultats obtenus ont permis d’identifier les éléments minéraux qui contribuent à l’encrassement lors de la concentration de microfiltrat et d’ultrafiltrat de lait, de lactosérums acides chlorhydrique et lactique. Afin de dépasser l’extrait sec maximal en sortie des évaporateurs à flot tombant, deux évaporateurs rotatifs à couche mince, de conceptions différentes, ont été testés à l’échelle pilote. Les études de faisabilité ont été menées jusqu’à la poudre. Le potentiel des équipements a été évalué suivant les propriétés fonctionnelles des poudres et le coût énergétique d’élimination de l’eau. Dans l’un des cas, le remplacement de la tour de séchage par deux évaporateurs rotatifs en série constitue une rupture technologique pour la production de poudres de perméat et dimi / Dairy powders are produced using a two-step process: concentration of the liquid product (membrane, concentration by vacuum evaporation) and drying of the concentrate. Contrary to spray-drying, vacuum concentration has been poorly investigated. However, a better understanding of this unit operation carried out in falling-film evaporators would lead to an improved control of the global process scheme for the production of powders. This PhD project aims to highlight how to enhance the performances of falling-film evaporators; it focuses on two limiting factors of the vacuum concentration: the fouling of the heating surfaces and the maximal viscosity at the outlet of the falling-film evaporators. The contribution of the different product components to the fouling was investigated using a methodology developed at pilot-scale.Our results showed which mineral elements favored the fouling of falling-film evaporators during the concentration of milk microlfiltrate and ultrafiltrate as well as hydrochloric and lactic acid wheys. Besides, two thin-film rotative evaporators of different designs were tested at pilot-scale in order to exceed the maximum dry matter achieved in falling-film evaporators. The feasibility studies were conducted up to the production of powders. The capabilities of the equipment were evaluated according to the functional properties of powders and the specific energy costs relative to the removal of water. In one case, the combination of two rotative evaporators replacing the spray drier constitutes a technological breakthrough in the production of permeate p

L’anarchia désigne au sens propre la vacance du pouvoir dans la sphère militaire (la mort du chef sur le champ de bataille) et dans la sphère politique (la vacance de la magistrature, en particulier éponyme). La notion est vite devenue plus générale et exprime au figuré le manque ou le refus du commandement. Elle se rapproche des sens d’insubordination, insoumission, indiscipline, licence et désordre. L’expérience effective de la vacance du pouvoir dans les cités grecques, sa représentation et sa conceptualisation constituent les axes principaux de cette recherche. L’anarchia est envisagée à l’échelle de l’âme, de la famille, de la cité, voire de l’univers. Elle engage une réflexion sur l’articulation entre deux principes a priori antagonistes, l’aspiration à la liberté et la nécessité de l’ordre, et par conséquent sur les fondements de l’exercice légitime du pouvoir. L’étude repose sur l’analyse précise des emplois du terme anarchia dans les sources épigraphiques, historiques, littéraires et philosophiques. La première partie envisage les vacances effectives des magistratures dans le cadre du cours normal ou d’une rupture du fonctionnement des institutions ainsi que les palliatifs mis en place. Les occurrences du terme anarchia concernent les cités d’Athènes, Thasos, Téos, Syros et Bérénikè. S’ajoutent les emplois problématiques des termes akosmia à propos du régime crétois par Aristote et atagia dans les inscriptions thessaliennes. La deuxième partie envisage l’évolution sémantique du terme de l’absence de chef à l’anarchie chez les historiens et les poètes tragiques et la place de l’anarchia dans les théories du commandement élaborées par Xénophon, Platon et Aristote. / The term anarchia refers literally to the absence of power, in the military sphere (that caused by the loss of a commander), and the political sphere (the absence of archontes, specifically the eponymous archon). The concept quickly generalised, coming to designate in the figurative sense the lack and want of power or the rejection and negation of power. It approaches the meanings of insubordination, rebelliousness, unruliness, licentiousness and disorder. The actual experience of power vacuum in the cities of Ancient Greece and how the Greeks represented it and conceptualised it are the three main lines of this research. Anarchia is conceived not only in the city but also in the soul of the individual, in the family, or even in the universe. It demands reflection on the articulation between two seemingly antagonistic principles, the desire for freedom and the necessity of order, and consequently upon the foundations of legitimate authority. This work relies on a precise analysis of the term anarchia in the epigraphic, historical, literary and philosophical sources. The first part deals with actual periods of power vacuum in the ordinary course of political life or in the context of institutional disruption and the implemented remedies. The term anarchia is employed in the cities of Athens, Thasos, Teos, Syros and Berenike. One must add the problematical use of the terms acosmia by Aristotle regarding the Cretan regime and atagia in the Thessalian inscriptions. The second part deals with the semantic evolution of the term from the absence of ruler to anarchy in the work of historians and tragic poets and the role of anarchia in the theory of leadership developed by Xenophon, Plato and Aristotle.

Gegenstand dieser Arbeit ist die retrograde Bewegung des Vakuumbogens, einer Bewegung des Bogenfußes entgegen der Lorentz-Kraft. Die retrograde Bewegung wird auf die Bewegung der Brennflecke des Kathodenansatzes zurückgeführt. Es wurden die Unterstrukturen der Brennflecke und ihre Bewegung im Magnetfeld untersucht. Dabei wurden bekannte makroskopische Erscheinungen (Plasmakante entlang der Magnetfeldlinien) erstmalig beobachteten mikroskopischen Erscheinungen (Jets) zugeordnet. In der vorliegenden Arbeit wurden die Eigenschaften der Jets bestimmt. Desweiteren wurde aus Untersuchungen zur Schrittweite und zeitlichen Abfolge der Brennfleckbewegung unter dem Einfluß des externen Magnetfeldes abgeleitet, daß die zufällige Bewegung des Brennflecks und seiner Bestandteile im magnetfeldfreien Fall auf kleineren Orts- und Zeitskalen als die retrograde Bewegung des Brennflecks (200...300µm) und (1...4µs) erfolgt und damit auch verschiedene Mechanismen ihre Ursache sind. Die beobachteten Jets, die aus dem Brennfleckkern emittiert werden, liefern eine Erklärung für die retrograde Bewegung. In den Jets werden elektrische Felder generiert, welche zur Neuzündung von Brennflecken beitragen. Sie sind der Hauptgrund für die Asymmetrie auf der retrograden Seite (Jets) und der Vorwärtsrichtung (keine Jets). Außerdem konnte gezeigt werden, daß bei heißen Kathoden keine Bewegungsumkehr der retrograden Bewegung erfolgt. Dadurch konnte Klarheit in Bezug auf ältere Veröffentlichungen geschaffen werden, die der retrograden Bewegung eine solche Erscheinung zugeordnet haben. / This thesis treats the phenomenon of retrograde motion of vacuum arcs, the motion of the arc root in the opposite direction of the Lorentz-force. The retrograde motion is attributed to the motion of the cathode spots. The sub-structures of cathodes spots and their motion in a magnetic field were examined. Known macroscopic phenomena (plasma edge along the magnet field lines) were related to observed microscopic phenomena (jets). These jets have been observed for the first time and their properties have been determined. From investigations of typical step widths and time constants of the cathode spots' motion in an external magnetic field it was derived, that random walk and retrograde motion of cathode spots and its fragments in the magnetic field-free case occur on smaller spatial (200...300µm) and temporal (1...4µs) scales than the retrograde motion of the spot. This leads to the conclusion that the mechanisms of both types of motion are different. The observed jets, which are emitted from the spot core, supply an explanation for the retrograde motion. Within the jets electrical fields are generated, which contribute to the ignition of new cathode spots. The jets are the reason for asymmetry on the retrograde side (jets) and the forward direction (no jets). Additionally it could be shown that with hot cathodes no reversal of the retrograde motion occurs. This cleared the assertion of older publications that a reversal of the retrograde motion is linked to the cathode temperature.

Este trabalho estuda as variáveis que influenciam as estimativas de recalques em aterros sobre solos moles com drenos verticais e pré-carregamento com vácuo. É realizada revisão bibliográfica em duas vertentes. Primeiro sobre as teorias de adensamento vertical, radial e com sobrecarga de sucção a vácuo, aplicadas no Estudo de Caso e necessárias para a estimativa dos recalques. Segunda sobre probabilidade e estatística aplicada à geotecnia, utilizada para contemplar a variabilidade e a incerteza dos parâmetros geotécnicos de forma científica. Na prática, a dificuldade interposta por custo e prazo para determinação dos parâmetros geotécnicos necessários para o desenvolvimento do projeto determinaram se a propriedade geotécnica buscada seria definida diretamente ou estimada por meio de propriedades índice, ambos os casos apresentando incertezas. Lambe (1973) discutiu a acurácia dos projetos geotécnicos e concluiu que somente com a compatibilidade entre dados e métodos é que se obtêm previsões geotécnicas acuradas. Análises de recalques são realizadas a partir dos dados do Estudo de Caso, de acordo com as questões práticas importantes: a magnitude dos recalques e o tempo necessário para o seu desenvolvimento. São interpretados ensaios de adensamento em laboratório do Estudo de Caso a respeito da sua qualidade, dos parâmetros geotécnicos medidos e da representatividade da amostra em relação ao solo aluvionar heterogêneo tratado. Dois métodos de cálculo da sobrecarga a vácuo são utilizados, a saber: constante com a profundidade, de uso corrente e mais simples; e decrescente com a profundidade, conforme teoria recente e mais sofisticada. Os parâmetros geotécnicos inferidos pelas sondagens e ensaios realizados são comparados com os parâmetros aferidos de melhor ajuste à instrumentação por meio de retroanálise paramétrica. Para melhor compreender a importância e influência das variáveis que afetam a acurácia das análises realizadas são utilizados métodos probabilísticos a partir das informações disponíveis. Por fim, os resultados obtidos em ambos os locais e com os métodos de previsão utilizados são confrontados quanto à acurácia obtida. / The present research studies the variables that influence settlement estimates in embankments on soft soil with vertical drains and vacuum preloading. The analysis of the existing literature on the topic is twofold. Firstly, it concerns the theories on vertical and radial consolidation, as well as consolidation under vacuum overload, applied in the Case Study and necessary for estimating settlements. Secondly, it regards probability and statistics applied to geotechnics, used to take into account the variability and uncertainty of geotechnical parameters in a scientific manner. In practice, the difficulty posed by costs and deadlines when defining the geotechnical parameters that are necessary for developing the project determined whether the geotechnical property sought would be either directly defined or estimated through index properties, with both scenarios presenting uncertainty. Lambe (1973) discussed the accuracy of geotechnical predictions and concluded that it is only possible to obtain accurate geotechnical forecasts when data and methods are compatible. Settlement analyses are performed based on data from the Case Study, according to important practical issues: settlement levels and the time that is necessary for its development. Consolidation laboratory tests concerning the Case Study are interpreted regarding their quality, the geotechnical parameters measured and sample representativeness in relation to the heterogeneous alluvial soil that has been treated. Two methods for calculating vacuum overload are used, namely, one that is constant with depth (simpler and more broadly used) and one that decreases with depth (following a more recent and more sophisticated theory). The geotechnical parameters inferred through borings and tests that have been carried out are compared with the parameters that best suit instrumentation through parametric back analysis. With a view to better understanding the importance and influence of the variables that affect the accuracy of the analyses performed, probabilistic methods are employed based on the information available. Finally, the results obtained in both sites and through the forecast methods used are compared in regard to the accuracy obtained.