Afin d'enrayer le dérèglement climatique actuel dû à l'utilisation à grande échelle de combustibles fossiles comme source d'énergie, une transition vers des énergies non émettrices de dioxyde de carbone est nécessaire. L'hydrogène, vecteur d'énergie neutre en dioxyde de carbone, pourrait y jouer un rôle important. Cependant, ses propriétés thermodynamiques interdisent de le stocker pur à des pressions modérées dans un volume raisonnable pour alimenter un véhicule. Le stockage solide sous forme d'hydrure métallique semble être une solution prometteuse à ce problème. Les alliages de structure cubique centrée à base de vanadium étant légers comparés aux alliages à base de terres rares étudiés depuis les années 1970, cette thèse a pour objet l'étude des propriétés d'hydrogénation (pression d'équilibre et capacité d'absorption notamment) d'alliages du système Fe Ti-V. Les composés à étudier devant être de structure cubique centrée et la limite de solubilité du fer dans cette phase du système Fe-Ti-V n'étant pas documentée de manière fiable, la première partie du travail a consisté en l'approfondissement des connaissances sur le diagramme d'équilibre grâce notamment à la détermination des sections isothermes à 1000 °C et 1200 °C. Pour cela, des échantillons massifs ont été synthétisés par fusion en four à arc puis recuit en four résistif. Les relations de phases ont été systématiquement analysées par diffraction des rayons X sur poudre et microsonde électronique. Grâce à ces techniques, nous avons pu montrer qu'après recuit à 1000 °C, la limite de solubilité du fer dans un alliage Ti-V dépasse 15 at.% pour tout rapport Ti/V. Lorsque la température de recuit est portée à 1200 °C, cette limite de solubilité dépasse 20 at.% de fer quel que soit le rapport Ti/V < 1. Une réaction quasi-péritectique a également pu être mise en évidence à 1140 °C et une projection de la surface liquidus est proposée, basée sur l'analyse de la microstrucure des échantillons. La seconde partie de notre travail a consisté en l'étude sur banc manométrique des propriétés d'hydrogénation d'échantillons de structure cubique centrée. Il en ressort que la majorité des composés étudiés ont une capacité totale à température ambiante de 1,7H/M, soit 3,4 wt.%, ou 140 g_L-1, la capacité réversible s'élevant à 0,98H/M, soit 1,93 wt.%, ou 82,5 g_L-1 (densité supérieure à celle du dihydrogène liquide) pour l'échantillon de compositionTi10V88Fe2. La dépendance entre l'enthalpie d'hydrogénation et la compositiondes échantillons est linéaire et a été déterminée. On peut ainsi, en fonction de la composition choisie, obtenir des pressions d'équilibre allant de 0,1 bar à plus de 100 bar. Une étude structurale par diffraction des rayons X pour de faibles concentrations en hydrogène a mis en évidence la déformation de la maille cubique en maille quadratique lorsque la quantité d'hydrogène absorbé augmente. La cinétique d'absorption des échantillons de structure cubique centrée est par ailleurs très avantageuse, puisqu'une minute suffit pour que 90% de la capacité totale soit atteinte. En revanche, on observe un ralentissement de la cinétique en fonction du nombre de cycles appliqués. Toutefois, ce type d'alliage reste prometteur pour des applications de stockage de l'hydrogène

The purpose of this study is to examine the overland trade with northern Mexico as international trade, to analyze its unique role in the economic development of both New Mexico and Missouri, and to evaluate the influence of Mexican gold and silver on the economic development of Missouri. The economic development of the United States between the beginning of the Revolution and the Civil War was attended by uncertainty, risk, and experimentation. The United States was exceedingly poor in specie, had almost no liquid capital, and its international credit rating was not well established. The United States currency system was based on paper money in contrast to that of New Spain and Mexico.Chapter I discusses the vagaries of a paper currency system, especially when the young nation was trying to establish its international credit rating, fight a war with England, and develop a wilderness on its western frontier. The problems were made more difficult because citizens of the United States lacked not only financial experience, but also adequate liquid capital. Mexico, however, had gold and silver ores and the capacity to mint coin. Northern Mexico was handicapped by Spanish commercial policies; until independence in 1821, it had little industrial capacity and almost no mercantile facilities. Chapter II provides an overview of New Mexico in 1820. Taken together, these two chapters show the mutual economic benefit to be derived by both New Mexico and Missouri from the development of the trade.Chapter III is a detailed chronological study of the events of the first decade of the trade between Santa Fe and Missouri. It brings together into one place the most up-to-date information on the participants in the trade from 1820-1830. Comparisons are made between the Anglo-American sources and the Spanish-American records; an effort is made to fill in as many gaps as possible and to check the accuracy of both sets of records. In this chapter the chief participants in the trade are studied.Chapter IV studies the nature of banking, credit, and currency problems in Missouri. It shows the tendency of people on the frontier of the United States to resort to experimentation in their efforts to deal with deflation, recession, and depression. Particular emphasis is given the panics of 1819 and 1837. The chapter also shows the effects in St. Louis of rapid growth and inflation. The unique role of Mexican gold and silver in the establishment of Missouri finance is studied. Between 1830 and 1840, as Chapter V shows, the merchant-capitalists of St. Louis replaced the farmer-merchants of the period 1820-1830, and the exchange of trade goods for Mexican specie and bullion increased steadily. The specie flow to Missouri reversed the usual United States frontier economic condition. Missouri accumulated enough liquid capital to launch St. Louis into position of "the Gateway to the West" as the great movement of people to California and Oregon began in the 1840's.In Chapter VI, a comparison of coin in circulation in the United States and coins minted by the United States correlates with the specie flow from Mexico to Missouri. The data vindicates the thesis that the key to St. Louis' financial success in the early years of Missouri's statehood lay in its trade with northern Mexico which resulted in the accumulation of the most valuable of all commodities, gold and silver specie and bullion.

This thesis refers to a simulation of an adhesive joint used to bond two metal sheets of a component of the side skirt bracket implemented in trucks. The adhesive joint must support fatigue and mixed-mode loading. The principal goal is the implementation of a novel material model, which governs the damage produced by a mixed-mode fatigue loading in a rubber adhesive layer. Two approaches to define the material model are implemented: the filament model and the principal strain model. The models are fitted against experiments, which have been performed parallel to the development of this thesis by the Mechanics of Materials (MoM) research group of the University of Skövde. The models incorporate fitting parameters with the aim of adjusting the models against experimental results. Simulations are performed using the Finite Element (FE) software, ABAQUS, and the material models are implemented using UMAT subroutines. The filament model is inaccurate and it is considered unable to model the mixed-mode behaviour of the adhesive joint. The principal strain model is considered a well-established method to define the damage and to predict the fatigue life of the adhesive under fatigue in mixed-mode loading.

The diesel engine is growing in popularity due to its energy efficiency and solving the emissions issues associated with diesel engine exhaust would clear the way for further growth. The key pollutants are NOx, particulate matter and unburned hydrocarbons. Selective catalytic reduction (SCR) catalysis is likely the best choice for NOx control. In SCR, NH3 selectively reacts with NOx to form N2 – the selectivity refers to NH3 reacting with NOx instead of the abundant O2. Urea is used as the NH3 source, being injected into the exhaust as an aqueous solution where the urea decomposes and NH3 is generated. Spatial resolution characterization techniques have been gaining attention in the catalysis field because of the higher level of information provided. In this thesis, a new spatial resolution technique, called SpaciFTIR (spatially-resolved, capillary-inlet Fourier transform infra-red spectroscopy), was developed, which overcomes the interference of water in the detection of NH3 in an earlier developed technique, SpaciMS (spatially-resolved, capillary-inlet mass spectrometry). With the new test method, three SCR topics were addressed. First, the three key SCR reactions were spatially resolved. These are the standard SCR reaction (2NO + 2NH3 + 1/2O2 = 2N2 + 3H2O), the fast SCR reaction (NO + NO2 + 2NH3 = 2N2 + 3H2O), and NO2-SCR, (6NO2 + 8NH3 = 7N2 + 12H2O). Results show that in the presence of NO2, but at a NO2/NOx ratio < 0.5, the fast SCR reaction proceeds followed by the standard SCR reaction, i.e. in series. If the NO2/NOx ratio exceeds 0.5, the NO2-SCR and fast SCR reactions occur in parallel. Compared to the standard integral test method, this spatial resolution technique clearly showed such trends. Secondly, the spatial resolution technique was used to characterize the effects of thermal aging on catalyst performance. It was found that for a highly aged catalyst, there was a radial activity profile due to an inhomogeneous temperature distribution in the process of aging. Aging effects on various key SCR reactions, i.e. NO oxidation, NH3 oxidation, and the reduction reactions, were studied. Last but not least, for the purpose of passive SCR system development, transient NH3 storage profiles along the monolith channel were measured with SpaciFTIR. Passive SCR is a system where the NH3 is generated on an upstream catalyst, such as a three-way catalyst or lean-NOx trap, instead of via urea injection. In such a system, NH3 is therefore not constantly being fed to the SCR catalyst, but “arrives” in pulses. Factors such temperature, NH3 concentration, pulsing time, flow rate and thermal aging were investigated. For the first time, NH3 migration was observed and its effect on SCR reactions along the length of catalyst was studied.

In this dissertation, we develop multiscale finite element methods and uncertainty quantification technique for Richards' equation, a mathematical model to describe fluid flow in unsaturated porous media. Both coarse-level and fine-level numerical computation techniques are presented. To develop an accurate coarse-scale numerical method, we need to construct an effective multiscale map that is able to capture the multiscale features of the large-scale solution without resolving the small scale details. With a careful choice of the coarse spaces for multiscale finite element methods, we can significantly reduce errors. We introduce several methods to construct coarse spaces for multiscale finite element methods. A coarse space based on local spectral problems is also presented. The construction of coarse spaces begins with an initial choice of multiscale basis functions supported in coarse regions. These basis functions are complemented using weighted local spectral eigenfunctions. These newly constructed basis functions can capture the small scale features of the solution within a coarse-grid block and give us an accurate coarse-scale solution. However, it is expensive to compute the local basis functions for each parameter value for a nonlinear equation. To overcome this difficulty, local reduced basis method is discussed, which provides smaller dimension spaces with which to compute the basis functions. Robust solution techniques for Richards' equation at a fine scale are discussed. We construct iterative solvers for Richards' equation, whose number of iterations is independent of the contrast. We employ two-level domain decomposition pre-conditioners to solve linear systems arising in approximation of problems with high contrast. We show that, by using the local spectral coarse space for the preconditioners, the number of iterations for these solvers is independent of the physical properties of the media. Several numerical experiments are given to support the theoretical results. Last, we present numerical methods for uncertainty quantification applications for Richards' equation. Numerical methods combined with stochastic solution techniques are proposed to sample conductivities of porous media given in integrated data. Our proposed algorithm is based on upscaling techniques and the Markov chain Monte Carlo method. Sampling results are presented to prove the efficiency and accuracy of our algorithm.

Hi ha nombrosos estudis que fan constar la diversitat de déficits cognitius que pateixen les persones amb esquizofrènia. Aquests déficit es troben en diverses àrees (atenció, llenguatge, memòria i especialment les funcions executives = FE), i conseqüentment afecta al funcionament de la vida diària d'aquestes persones.Muñoz i Tirapu (2001) definiren "la síndrome disexecutiva" com una constel.lació d'alteracions cognitiva-conductuals relacionades amb l'afectació de les FE i que en persones amb esquizofrènia afecta als següents elements: dificultat per centrar-se en una tasca i finalitzar-la sense un control ambiental extern; presència d'un comportament rígid, perseverant i en ocasions amb conductes estereotipades; dificultats en l'establiment de nous repertoris conductuals juntament amb una absència d'estratègies operatives, de creativitat i amb una mancança de flexibilitat cognitiva. Entre els diferents models de rehabilitació, hi ha autors com (Roder i cols. 1996) que proposen models integradors (programa ITP) suggerint un programa terapèutic tenint present la influència interactiva de les variables biològiques, cognitives i ambientals.Els objectius generals d'aquest estudi són: avaluar l'eficàcia del programa d'entrenament cognitiu de les funcions executives i el manteniment dels resultats obtinguts després del programa al cap de sis mesos d'haver finalitzat aquest. Els criteris d'inclusió dels subjectes a l'estudi són: diagnòstic d'esquizofrènia (DSM-IVTR). La mostra estava formada per 19 subjectes: el grup d'estimulació cognitiva (GEC) amb 12 pacients i el grup control (GC) format per 7 pacients. Els dos grups només es diferenciaven perquè en el grup GEC es va aplicar el programa d'entrenament cognitiu de sis mesos, i el grup GC no va rebre cap tipus de programa terapèutic.Es va administrar a tots els subjectes tres avaluacions cognitives aplicant les mateixes proves en tres moments diferents (la primera avaluació: abans d'iniciar el programa, la segona avaluació que s'administrava immediatament després d'haver finalitzat el programa, i la tercera avaluació administrada sis mesos després d'haver finalitzat els sis mesos de programa d'entrenament cognitiu). Les proves consistien en diferents mesura d'avaluació, entre d'altres, de la qualitat de vida, simptomatologia, rendiment executiu i funcional (DEX, PANSS, QLS, Test of Porteus, Tower of London i WCST).El programa d'entrenament de sis mesos de duració administrat al grup GEC consistia en tres fases: la primera fase estava formada per exercicis de raonament abstracte i formació conceptual; la segona fase per tasques de planificació i seqüenciació de diverses accions; i la tercera consistia en la resolució de problemes reals dels pacients.Els resultats obtinguts mostra efectivitat en el programa d'entrenament cognitiu de les funcions executives, i en concret, en el raonament conceptual i abstracte, planificació i seqüenciació, i resolució de problemes. Aquesta millora es manté sis mesos després d'haver finalitzat el programa.Probablement els efectes obtinguts en el programa han generat una influència positiva en la disminució de la simptomatologia i un augment en el rendiment funcional executiu i de qualitat de vida. / "Study of the efficacy of an executive training program (ETP) applied to people with schizophrenia"TEXT:It was carried out/applied a cognitive training program to schizophrenic people. Muñoz i Tirapu (2001) defined the "disexecutive syndrome" in reference to the fact that these patients have difficulties in concentrating on an activity, in planning and in having lack of creativity and mental flexibility. Some authors propose integrating models (Roder et al. 1996). Following this approach, this training program of the executive functions has been developed (ETP). The objectives of this study were two: firstly to evaluate the efficiency of an ETP applied to people with schizophrenia and secondly to evaluate the maintenance of the results after the program.To people with schizophrenia were divided into two groups (19 patients): the cognitive training group (CTG) (12 patients) and the control group (CG) (7 patients). All subjects underwent three cognitive evaluations (initial, 6 months and 12 months) that assessed symptoms, quality of life, functional performance and executive functions. The tests carried out, among others, were: DEX, PANSS, QLS, Test of Porteus, Tower of London and WCST.The ETP lasted 6 months and included exercises of planning, problem solving and abstract reasoning. For example, several exercises of planning (journeys, culinary dishes and some other sequential actions), and reasoning exercises about daily life situations and problem-solving trainingThe CTG obtained better scores immediately after the ETP. The patients of this group partially maintained these results in the evaluation done 6 months after the finishing of the program. These positive results are mainly observed in the capacity of planning, mental flexibility, abstract reasoning and problem solving. An improvement was also observed in the rest of parameters that were evaluated.The results show the effectiveness of the cognitive training program that not only appeared immediately after the program, but with the 12 months followup.The effects of the ETP may have had a positive influence in the decreased of the schizophrenic symptomathology and, therefore, an increase of quality of life and functional performance.

The work material in metal working operations always showssome kind of anisotropy. In order to simplify the theoreticalanalysis, especially considering bulk deformation processes,anisotropy is usually neglected and the material is assumed tobe isotropic. On the other hand, the analysis that consideredthe influence of anisotropy seldom incorporates the influenceof friction. For predicting the material flow during plasticdeformation and for predicting the final material properties ofthe product, adequate descriptions of both flow stress curvesand coefficients of friction have to be developed. In the present work a number of experimental methods fordetermining the anisotropy have been utilized and compared:Yield loci, strain ratios (R-values) and establishing flowstress-curves in different directions. The results show thatthe yield loci measurements are weak in predicting anisotropywhen the material strain hardening is different in differentdirections. It is concluded that also the strain ration(R-value) measurements are unreliable for describinganisotropy. The most trustable and useful results were foundfrom multi-direction determinations of the flow stresses. Three typical cases of ring upsetting conditions wereanalyzed by theory (3D-FEM) and experiments:     An anisotropic ring, oriented 900 to the axis ofrotational symmetrical anisotropy. The friction coefficientwas the same in all directions     An isotropic ring. The friction coefficient was differentin different directions     An anisotropic ring oriented 00 to the axis of rotationalsymmetrical anisotropy. The friction coefficient was the samein all directions The cases 1) and 2) reveal that the influence of anisotropyon the ring deformation is quite similar to that obtained bychanging the frictional condition. The case 3) exposes that ifthe material flow caused by anisotropy is incorrectly referredto friction, the possible error of the friction coefficient canbe as high as 80% for a pronounced anisotropic material. Amodified two-specimen method (MTSM) has been establishedaccording to an inverse method. Experiments were carried ascylinder upsetting. Here both ordinary cylinders were used aswell as so-called Rastegaev specimen. Also plane straincompression tests were utilized. The results show that MTSM isable to evaluate the validity of a selected mathematical modelwhen both the friction coefficient and the flow stress areunknown for a certain process. MTSM can also be used toestimate the friction coefficient and flow stress provided thatthe selected mathematical model is adequate. <b>Key words:</b>Anisotropy, friction coefficient, flowstress, modified two-specimen method and FE-analysis / NR 20140805

Thesis (Ph. D.)--Texas State University--San Marcos, 2009. / Vita. Appendices: leaves 133-163. Includes bibliographical references (leaves 16-20, 52-53, 87-91, 116-119, 130-132). References in more than one sequence of leaves. Also available on microfilm.

Doutor -- Escola Nacional de Saude Publica, Rio de Janeiro, 2003.

abstract: To extend the lifetime of complementary metal-oxide-semiconductors (CMOS), emerging process techniques are being proposed to conquer the manufacturing difficulties. New structures and materials are proposed with superior electrical properties to traditional CMOS, such as strain technology and feedback field-effect transistor (FB-FET). To continue the design success and make an impact on leading products, advanced circuit design exploration must begin concurrently with early silicon development. Therefore, an accurate and scalable model is desired to correctly capture those effects and flexible to extend to alternative process choices. For example, strain technology has been successfully integrated into CMOS fabrication to improve transistor performance but the stress is non-uniformly distributed in the channel, leading to systematic performance variations. In this dissertation, a new layout-dependent stress model is proposed as a function of layout, temperature, and other device parameters. Furthermore, a method of layout decomposition is developed to partition the layout into a set of simple patterns for model extraction. These solutions significantly reduce the complexity in stress modeling and simulation. On the other hand, semiconductor devices with self-feedback mechanisms are emerging as promising alternatives to CMOS. Fe-FET was proposed to improve the switching by integrating a ferroelectric material as gate insulator in a MOSFET structure. Under particular circumstances, ferroelectric capacitance is effectively negative, due to the negative slope of its polarization-electrical field curve. This property makes the ferroelectric layer a voltage amplifier to boost surface potential, achieving fast transition. A new threshold voltage model for Fe-FET is developed, and is further revealed that the impact of random dopant fluctuation (RDF) can be suppressed. Furthermore, through silicon via (TSV), a key technology that enables the 3D integration of chips, is studied. TSV structure is usually a cylindrical metal-oxide-semiconductors (MOS) capacitor. A piecewise capacitance model is proposed for 3D interconnect simulation. Due to the mismatch in coefficients of thermal expansion (CTE) among materials, thermal stress is observed in TSV process and impacts neighboring devices. The stress impact is investigated to support the interaction between silicon process and IC design at the early stage. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011