Aços de alta resistência e baixa liga (ARBL) têm sido bastante utilizados na fabricação de tubulações para o transporte de petróleo e gás. Entretanto, o uso destes materiais em meios com elevadas concentrações de H2S, denominados sour, tem resultado em falhas frequentes, devido à suscetibilidade destes materiais ao desenvolvimento do fenômeno de trincamento induzido pelo hidrogênio (Hydrogen Induced Cracking - HIC), assim como devido a problemas de corrosão. O desenvolvimento de diferentes processos tecnológicos para a produção de tubos de aços ARBL, tais como a laminação controlada e resfriamento acelerado, a adição de microligantes, assim como a diminuição do teor de enxofre, fósforo, carbono e manganês, tem levado à elaboração de materiais com propriedades mecânicas otimizadas, permitindo também um melhor controle da microestrutura. As perdas de dureza e resistência mecânica devidas à redução do teor de manganês, são compensadas pela adição de elementos como cromo e nióbio. Neste trabalho estão sendo comparadas a resistência à corrosão e os parâmetros de permeabilidade do hidrogênio de dois tubos de aço API 5L X65 e uma chapa API 5L X65, todos do tipo ARBL e com baixo manganês (0,27%) e alto nióbio (0,083% a 0,090%), na solução B da norma NACE, TM-0284 (2011). Para isto, foram realizados ensaios de potencial de circuito aberto (Open Circuit Potential - OCP), espectroscopia de impedância eletroquímica (Electrochemical Impedance Spectroscopy - EIS) e curvas de polarização potenciodinâmicas no eletrólito naturalmente aerado, desaerado e saturado com H2S. Os testes de permeabilidade do hidrogênio foram realizados com base na norma ASTM INTERNATIONAL G148 - 97, porém usando a célula modificada de DEVANATHAN e STACHURSKY (1962) e com H2S como veneno catódico. Os materiais foram caracterizados por microscopia óptica (MO), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva de Raios-X (X-Ray Energy Dispersive Spectroscopy - EDS) antes e depois de testes de imersão nos diferentes eletrólitos. Caracterização dos produtos de corrosão por difração de raios-X (DRX) também foi realizada após imersão em meio saturado com H2S (sour). As análises por MO e MEV mostraram matrizes ferríticas para os três aços, com a presença de baixos teores do microconstituinte martensita/austenita (M/A), de perlita e com baixo nível de inclusões uniformemente distribuídas e com composições químicas semelhantes. Os resultados dos ensaios de corrosão mostraram que, para todos os meios investigados, o aço denominado como B apresentou a melhor resistência à corrosão, enquanto aquele denominado como C se mostrou o mais suscetível em todas as condições estudadas. Para os três aços, a resistência à corrosão apresentou a seguinte ordem crescente de acordo com o meio de exposição: meio saturado com H2S < meio naturalmente aerado < meios desaerados. Ensaios de OCP e EIS no meio saturado com H2S em um período de 24h mostraram que a resistência à corrosão aumenta com o tempo em razão da formação de uma camada de sulfeto de ferro, que, no entanto, se apresentou pouco aderente. Os resultados dos ensaios de permeação de hidrogênio mostraram que o aço denominado B, que apresentou maior resistência à corrosão em todos os meios e que não apresenta perlita em sua microestrutura, teve o maior valor de difusividade efetiva de hidrogênio, menor concentração de hidrogênio atômico na sub-superfície e menor quantidade de traps por unidade de volume. Quanto aos outros dois materiais, os resultados dos testes de permeabilidade ficaram em desacordo com os resultados da caracterização microestrutural e dos testes de resistência à corrosão, indicando que fatores diferentes dos detectados neste estudo são importantes para governar essas propriedades. / High strength low alloy (HSLA) steels have been widely used in the manufacture of pipelines for the transport of oil and gas. However, the application of these steels in media with high H2S concentrations, denominated sour, has resulted in frequent failures due to the susceptibility of these materials to the development of Hydrogen Induced Cracking (HIC) phenomena, as well as due to corrosion problems. The development of different technological processes for HSLA piping production, like controlled rolling and accelerated cooling, the addition of microalloying elements, as well as the reduction of the amounts of sulphur, phosphorus, carbon and manganese, has led to the development of materials with optimized mechanical properties, also allowing a better microstructural control. Hardness and mechanical resistance reduction due to the lowering of Mn content are compensated by niobium and chromium addition. In this work, the corrosion resistance and the hydrogen permeability parameters of two API 5L X65 steel tubes and an API 5L X65 plate, all HSLA type and with low manganese (0.27%) and high niobium (0.083% to 0.090%) contents, are compared in solution B of NACE standard TM-0284 (2011). For this, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves were carried out in the naturally aerated, deaerated and H2S saturated electrolyte. Hydrogen permeability tests were performed based on ASTM INTERNATIONAL G148-97, but using a modified DEVANATHAN and STACHURSKY (1962) cell and with H2S as cathodic poison. The materials were characterized by means of optical microscopy (OM), scanning electron microscopy (SEM) and X-Ray Energy Dispersive Spectroscopy (EDS) prior and after immersion tests in the different electrolytes. Characterization of the corrosion products by X-ray diffraction (XRD) was also performed after immersion in the H2S-saturated (sour) medium. The OM and SEM characterization showed ferritic matrices for the three steels, with the presence of low levels of the martensite/austenite (M/A) microconstituent, perlite and with a low level of inclusions evenly distributed and with similar chemical compositions. The results of the corrosion tests showed that, for all investigated media, the steel denominated as B presented the best resistance to corrosion, whereas the one denominated as C showed to be the most susceptible in all the conditions studied. For the three steels, the corrosion resistance showed the following ascending order according to the exposure medium: H2S saturated < naturally aerated medium < deaerated media. OCP and EIS tests in the H2S-saturated medium in a period of 24 hours showed that the corrosion resistance increases over time due to the formation of an iron sulphide layer, which, however, presented little adhesion. The results of the hydrogen permeation tests showed that the steel denominated B, that presented greater corrosion resistance in all media and that does not present perlite in its microstructure, had the highest values of effective hydrogen diffusivity, the lowest concentration of atomic hydrogen in the subsurface and the smallest amount of traps per unit volume. Concerning the other two materials, the results of the permeability tests were at variance with the results of the microstructural characterization and corrosion resistance tests, indicating that factors other than those detected in this study are important to govern such properties.

Vascular smooth muscle cells (VSMC) constitute an important component of blood vessels and are primarily responsible for vessel contraction. In vascular disorders such as hypertension and atherosclerosis as well as pregnancy and exercise, VSMC demonstrate increased capacity to proliferate and migrate, resulting in vascular remodelling. The actin cytoskeleton is an important component of vascular contractility and is also essential for proliferation and migration of VSMC. Vasoactive agonists such as Endothelin-1 (ET-1) and Noradrenaline (NA), have been shown to mediate VSMC contraction through changes in actin cytoskeleton and focal adhesion (FA) remodelling, and have also been reported to cause VSMC migration in the appropriate setting. The aim of this study was to investigate the signalling mechanisms responsible for FA dependent actin cytoskeleton remodelling of VSMC in response to ET-1 and NA, with a special focus on Hydrogen peroxide-inducible clone 5 (Hic-5). The latter is a FA protein shown to regulate actin cytoskeleton dynamics in small arteries in response to Noradrenaline (NA) and the response of VSMC to arterial injury and abdominal aortic aneurysm. We have shown that Src-dependent tyrosine phosphorylation of Hic-5 regulated its subcellular localisation in mouse embryonic fibroblasts and VSMC, but was not responsible for the effects of ET-1 and NA on actin filament remodelling or Hic-5 redistribution in VSMC. ET-1 stimulation caused an increase in Hic-5 localisation at FAs concurrent with an increase in the density of actin filaments, whereas NA stimulation caused a decrease in Hic-5 localisation at FAs in VSMC concurrent with actin filament redistribution at the cell cortex. Hic-5 was the FA protein that demonstrated the most dramatic changes in subcellular localisation in response to ET-1 and NA, when compared to paxillin (Hic-5 homologue) or vinculin (classical FA marker). NA-mediated changes in Hic-5 localisation and actin filament distribution were more pronounced compared to ET-1-mediated changes. Further investigation into the NA-induced changes suggested that actin filament disassembly preceded Hic-5 relocalisation from FAs to the cytosol. These results show that vasoactive peptides cause Hic-5 relocalisation and actin filament rearrangement in VSMCs in an agonist-dependent manner. Given that VSMC FA remodelling and actin cytoskeleton reorganisation occur during contraction and arterial remodelling, our data identify Hic-5 as a key regulator of these processes in response to NA and ET-1. Furthermore, these data have implications in agonist- specific VSM function such as migration and contraction.

The thesis describes the complex of basic testing procedures conducted by Euro NCAP company with a view to the examination of pedestrian protection in accordance with EEVC WG 17 and topical instruments used at passenger vehicles for pedestrian protection. It includes a detailed procedure of the creation of an adult head impactor including its certification and the formation of its impact on the bonnet of the vehicle. It is specialized in the studies how material properties influence the size of HIC criterion.

This thesis deals with the subject of crash tests Euro NCAP, concretely child-head impact test to the car bonnet. Object of thesis is make homogeneous car bonnet, where will remove stiffness places and also the bonnet global stiffness won´t be worst. The bonnet must carry out limits for pedestrian protection.

„Hic sunt leones“ is a printed publication that represents the outcome of diploma thesis Map of Brno. It is a pocket-size map in a form of a book describing the dark side of Brno, fitting contextually within the scope of urban exploration. Locations described within the publication are far beyond the general interest of the majority, and even the alternative minority, of population within the city. These are locations whose visit may result not just in dirty pants or possible conflict with the police, but also in injuries or even death. The inaccessibility of these places is emphasized by the inaccessibility of the map itself, which is being tested at it's very edge of usability. Accurate cartographic mapping is not the intention of this project, neither it is the process of making these places easily accessible. Mediation of their unique atmosphere and providing the evidence of their mere existence is the primary intention here. More so because of the fact that such places are subjects to very fast perdition.

The microstructure of steel is well known to affect hydrogen-induced cracking (HIC) susceptibility by having certain heterogeneities serving as effective hydrogen trap sites. A consensus on whether or not fine-scale niobium carbide (NbC), nitride (NbN) and carbonitride (Nb(C,N)) precipitates can behave as effective hydrogen traps has yet to be established. The H-trapping capacity of Nb precipitates in a Fe-C-Mn-Nb model steel was investigated with the goal of minimizing embrittlement effects and improving the design of X70 pipeline grade steel for sour service oil and gas applications. First, a heat treatment was applied to the model steel to change the Nb-based precipitate size distribution, which was subsequently characterized via transmission electron microscopy, electron energy loss spectroscopy, and atom probe tomography. The experimental heat treatment increased the number of fine-scale precipitates (<15 nm) that are ideal for APT characterization. NbN and NbC precipitates of various stoichiometries were confirmed within the steel. Further, a custom electrolytic H-charging device was designed, fabricated, and validated using thermal desorption spectroscopy. Additionally, the extent of galvanic corrosion between NbC and NbN and the steel matrix was determined using custom scaled-up particle matrix specimens. Potentiodynamic polarizations conducted using active and passivating electrolytes revealed the relative nobility of the materials. Both NbC and NbN particles were more noble than the steel matrix; thus, possessing driving force for galvanic corrosion, with the particles serving as cathodes. Future studies involving electrolytic charging of the steel in a D-based electrolyte coupled with atom probe tomography will facilitate the direct observation of H-trapping sites relative to various Nb-based precipitates and contribute to an improved understanding of the mechanisms governing HIC. / Thesis / Master of Science in Materials Science and Engineering (MSMSE)

No description available.

No description available.

Kvůli stále značnému počtu usmrcených chodců při dopravních nechodách se výrobci automobilů snaží pomocí vhodné konstrukce automobilu zmírnit následky způsobené nehodou. Při srážce impaktoru hlavy s kapotou automobilu dochází ke zpomalení impaktoru a na toto zpomalení je aplikováno HIC kitérium. HIC kritérium vyhodnocuje míru možnosti poranění hlavy při srážce. Cílem diplomové práce je výběr nejvhodnějšího časového průběhu zpomalení dětského impaktoru hlavy při srážce s kapotou automobilu Škoda Superb II z hlediska HIC kritéria a navržení konstrukčních úprav kapoty a okolních částí, které se dostanou do kontaktu tak, aby se skutečný průběh blížil teoretické fyziologicky přípustné variantě. Pro výpočtové modelování úlohy byla použita explicitní varianta metody konečných prvků (MKP). V první části práce jsou analyzovány data ze simulací úderu impaktoru dětské hlavy na kapotu auta, zvlástě pak analýzy částí energie spotřebované kapotou při srážce s impaktorem. Tyto data byly poskytnuté firmou Škoda Auto a.s. Další část se zaobírá návrhem křivek zpomalení se sinusovým, čtvercovým a trojúhelníkým tvarem. Dále je také navržena 2 vrcholová trojúhelníhová křivka zpomalení, jež je pomocí parametrů modifikovatelná. Optimalizací aproximovaného modelu geometrie kapoty automobilu při dopadu impaktoru hlavy na navržený model geometrie kapoty je zajištěno podobné shody s dříve optimalizovanou 2 vrcholovou trojúhleníkovou křivkou zpomalení. V další části je použit originální model geometrie kapoty automobilu Škoda Superb II a další optimalizace modelu geometrie kapoty vůči optimálnímu časovému průběhu zpomalení.

Cette thèse interroge les fondements de la pensée d’Ivan Illich et ses implications pour la manière d’être les uns avec les autres et pour le langage. La pensée d’Illich s’ancre dans une vision singulière de l’être humain en tant que créature qui atteint la perfection en s’engageant dans une relation à l’autre, une relation libre, gratuite, et pleinement incarnée. J’explore les formes que prend cette idée à travers trois grands axes qui traversent l’oeuvre d’Illich : la relation entre soi et l’autre, le rôle des institutions et la pratique du langage. Dans un premier temps, j’examine le geste de pensée d’Illich, c’est-à-dire la manière dont il tente de faire de la quête de vérité une pratique conviviale, entre amis. Il s’inscrit par là en lien avec la figure du Samaritain issue de la parabole des Évangiles, qu’il interprète toutefois de manière très personnelle, hors de la tradition chrétienne. Ce lien étroit au Samaritain ouvre la question du jeu entre la foi et l’intellect dans sa pensée. Dans un deuxième temps, partant de cette interprétation, j’expose la vision du monde et des rapports entre les êtres qui en découlent. Selon Illich, Jésus révèle qu’aucune règle ne peut me dicter qui est mon prochain : je me porte vers lui d’un geste libre et gratuit qui émerge des entrailles, comme celui du Samaritain envers le Juif. Les Évangiles ouvrent ainsi une possibilité inédite d’être les uns avec les autres au-delà des règles d’appartenance à un groupe (clan, ethnie, nation etc). Cette idée particulière amène Illich à percevoir les institutions et les organisations qui structurent la société occidentale comme le résultat d’une perversion de cette relation, puisqu’elles cherchent à garantir, par une structure ou un service, ce qui devait rester une vocation personnelle librement assumée. Pour Illich, c’est en renonçant à toute garantie et au pouvoir dans le monde, que nous pouvons encore être les uns avec les autres à la hauteur de notre vocation de créature. Les réflexions de Jean-Luc Nancy sur l’être-les-uns-avec-les-autres offrent ici un contrepoint qui répond aux intuitions d’Illich et montre à quel point elles débordent la tradition chrétienne en se tenant au plus près de la condition simplement humaine. Enfin, dans un troisième temps, j’aborde le langage comme revers incorporel de cette irréductible condition d’être les uns avec les autres. Selon Illich, la perversion atteint aussi la langue dans laquelle nous nous parlons. Il en retrace l’origine au Moyen-Âge, au moment où émergent la notion de « langue maternelle » et l’idée de l’enseigner. Illich montre néanmoins, par sa pratique et dans ses textes, qu’une parole non ii pervertie continue d’exister, rythmée par le silence de l’ascèse et de l’écoute. Les mots de Paul Celan sur la persistance de la parole dans un monde corrompu rejoignent ici ceux d’Illich, ils les relaient et y répondent : s’ouvre ainsi un riche dialogue sur la possibilité toujours présente, mais jamais garantie, de se parler les uns aux autres. À travers tous ces enjeux, la pensée d’Illich revient sans cesse à la dimension temporelle du hic et nunc, l’ici et maintenant entre nous, difficile à saisir par l’esprit. / This thesis explores the foundations of Ivan Illich’s thinking and its implications for language and for our ways of relating to one another. His thinking is rooted in a singular vision of the human being as a creature who achieves perfection by establishing a relationship that is free and fully incarnate. I explore this fundamental idea through three major lines of thought running through Illich’s oeuvre : relations between self and other; the role of institutions; the practice of language. In the first chapter I examine this vision through Illich’s way of thinking together with friends, a convivially practiced search for truth. He thus places himself in the filiation of the Good Samaritan from the parable of the Gospels. In Illich’s highly personal interpretation, which stands outside the mainstream Christian tradition, this parable bears on the relationship between faith and reason. In Illich’s view, Jesus reveals that no rule dictates who is my neighbor: the Samaritan’s gesture of charity toward the Jew is completely gratuitous and comes from a deeply felt unease (Illich refers to the Hebrew word rhacham, often translated as mercy). In the second chapter I discuss the worldview that results from such an interpretation. For Illich, the Gospels open up a unique opportunity to be with each other beyond the rules that frame various groups (clan, tribe, nation etc). This thinking leads him to perceive the institutions and organizations of Western society as resulting from a perversion of that opportunity, because they seek to guarantee—through a structure or a service—precisely what should remain a freely-chosen, personal inclination. Illich demonstrates that by renouncing any guarantee and power in the world, we can still be with each other and live up to our personal inclination as creatures. Jean-Luc Nancy’s thinking on being-one-with-another offers here a counterpoint to Illich’s intuition and shows how this intuition goes beyond the Christian tradition by fully adhering to the human condition. Finally, in the third chapter, I approach language as the intangible reverse side of the irreducible condition of being with one another. According to Illich, the language we speak has also been corrupted through institutionalization. He traces the origin of this corruption to the Middle Ages, with the emergence of the notion of "mother tongue" and of its transmission via teaching. Through both his practice and his writing, however, Illich shows that uncorrupted speech remains possible, when punctuated by the silence of asceticism and listening. The iv words of Paul Celan on the persistence of speech in a corrupt world relays and responds to Illich’s thoughts on this theme, thus opening a rich dialogue on the possibility—always present, but never guaranteed—to speak with one another. Interwoven throughout these themes is the temporal dimension of hic et nunc, the here and now between us, which constantly surfaces in Illich’s writings yet remains difficult to grasp with the human mind.