Orientadores: Sandro Guedes de Oliveira, Lúcia Duarte Dillon / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-17T17:53:23Z (GMT). No. of bitstreams: 1 Abreu_ElitaSelmarade_M.pdf: 3986219 bytes, checksum: 3254aa4fe691af01904819c1fb348ada (MD5) Previous issue date: 2010 / Resumo: O principal propósito dessa dissertação é estudar modelos de meio efetivo de física de rochas que conecte as propriedades petrofísicas e as propriedades elásticas, assim como a sua aplicação na investigação dessas propriedades em rochas carbonáticas. Inicialmente será feita uma introdução a alguns modelos de física de rochas para meio efetivo, conhecidos como modelo de Voigt-Reuss-Hill, modelo de Kuster & Toksöz, modelo Diferencial de Meio Efetivo e relação de Gassmann, com objetivo de estabelecer os parâmetros que serão medidos e utilizados no desenvolver do trabalho. Após essa parte introdutória, baseado no modelo de Xu-Payne, foram realizadas uma série de análises de atributos geométricos, como a distribuição de tipos de poros, obtidas através de lâminas petrográficas com intuito de descrever a correlação entre as propriedades petrofísicas e elásticas e assim poder calibrar o modelo teórico utilizado na predição dessas propriedades. Dessa forma, o modelo calibrado passa a desempenhar um papel mais condizente com o sistema poroso da rocha permitindo uma melhor correlação entre os parâmetros elásticos e petrofísicos. Os resultados obtidos mostram que a utilização da informação de lâminas petrográficas, na parametrização do modelo, torna o método mais robusto na predição e conexão das propriedades elásticas e petrofísicas de rochas carbonáticas, tornando confiável a mudança de escala rocha-perfil, bem como possibilitando a predição qualitativa de propriedade permo-porosas a partir da velocidade da rocha / Abstract: The main purpose of this dissertation is to study rock physics effective models that connect the petrophysics and elastic properties as well as its application on the investigation of these properties on carbonate rocks. Firstly, we make an introduction to some rock physics of effective models as: Voig-Reuss-Hill, Kuster&Toksöz, Differential Effective Medium, Gassmann¿s Relation, aiming at establishing the parameters that will be measured and used latter. After this introductory part and based on the Xu-Payne model, several geometric factors analysis was done like pore types distribution, obtained by thin sections, with the intention of describing the correlation between the petrophysics and elastic properties. In this way, the model becomes more compatible with the rock porous medium, allowing a better correlation between the petrophysics and elastic parameters. Our results show that using the thin section information on the model parametrization, the predictability and connectivity of petrophysics and elastic properties applied to carbonate rocks become more robust, making trustable the upscale rock-well log and also enabling the permo-porosity properties prediction, in a qualitative way, through the velocity measurements / Mestrado / Física / Mestra em Física

Les matériaux tellurites possèdent des propriétés optiques non linéaires exceptionnelles, avec des valeurs de la susceptibilité optique non linéaire d’ordre trois de l’ordre de 10 à 50 fois supérieures à celle de la silice pure, favorisant alors l’efficacité des effets non linéaires. L’origine de ces propriétés optiques exceptionnelles est associée non seulement à la présence de la paire libre mais aussi à une « délocalisation » électronique très forte le long des ponts Te-O-Te dans des chaînes polymérisées (TeO2)p. Ainsi, nos recherches expérimentales ont porté sur les deux systèmes ternaires suivants : TeO2-TiO2-ZnO (TTZ) et TeO2-GeO2-ZnO (TGZ).Les domaines vitreux ont été délimités, la stabilité thermique augmente en fonction de l’ajout de ZnO, TiO2 et GeO2. L’étude vibrationnelle réalisée par spectroscopie de diffusion Raman et réflectivité spéculaire infrarouge, a mis en évidence une faible dépolymérisation du réseau vitreux par rupture des chaînes formées via des ponts Te-O-Te. Pour les teneurs élevées en ZnO, ce dernier contribue à une compensation de cette rupture par la formation de nouveaux ponts Te-O-Zn et/ou Zn-O-Zn. Une étude complète des propriétés mécaniques a été menée à la fois à température ambiante et en fonction de la température, notamment au passage de la température de transition vitreuse. L’augmentation de la teneur en ZnO dans les verres TTZ et TGZ a augmenté globalement les modules élastiques. Enfin, la diminution de la susceptibilité optique non linéaire du troisième ordre avec l’ajout de ZnO, nous a permis de montrer l’importance de la présence de chaînes composées de ponts Te-O-Te dans la structure du verre à base de dioxyde de tellure. / Tellurite materials possess exceptional nonlinear optical properties, with values of the third-order nonlinear optical susceptibility are 10 to 50 times higher than in pure silica, favoring then the efficiency of the nonlinear effects. The origin of these exceptional optical properties is not only associated with the presence of the electronic lone pair, but also with the very strong electronic "delocalization" along Te-O-Te bridges in polymerized chains (TeO2)p. Our experimental researches concerned the following both ternary glass systems: TeO2-TiO2-ZnO (TTZ) and TeO2-GeO2-ZnO (TGZ).The glass formation domains were determined, the thermal stability increases with the increased amount of ZnO, TiO2 and GeO2. The vibrational study carried out using Raman spectroscopy and specular infrared reflectivity, revealed that the increase of the ZnO amount leads to a slight depolymerization of the glass network by breaking chains formed via Te-O-Te bridges. For higher ZnO contents, the latter contributes to a compensation of this break by the formation of new bridges: Te-O-Zn and/or Zn-O-Zn. Mechanical properties were studied at the same time at room and high temperature, in particular around the glass transition temperature. The increase of the ZnO content in TTZ and TGZ glasses increased globally elastic modulus. Finally, the decrease of the third-order nonlinear optical susceptibility with the increased ZnO concentration emphasizes the role of the presence of chains consisted of Te-O-Te bridges in the structure of the tellurite glass.

Huzuni is a composition for a sinfonietta ensemble comprised of flute, clarinet, oboe, bassoon, horn, trumpet, trombone, two percussion instruments, piano, violin, viola, violoncello, double bass. The inspiration for it began when I was told that my music was too guarded and that a greater degree of emotion was needed. Such a critical response led me to reflect on compositional techniques, styles, and approaches that were outside of my comfort zone, all of which became the inspiration for this work. Huzuni, Swahili for grief, , is a thirteen-minute single movement work in three sections that reflects the raw emotions in dealing with grief. The form of the composition exposes the five stages of grief-denial, anger, bargaining, depression and acceptance- first introduced in 1969 by Elisabeth Kübler-Ross who founded the Kübler-Ross Model. In Huzuni, we move through each stage slightly differently than in the grief model. The first section establishes denial that leads directly into the bargaining stage. Throughout this movement, g minor provides a sense of denial of truth, achieved in part because the traditional and expected g minor tonic-dominant-tonic progression is replaced with i-v-vi. This replacement weakens g minor and sets up different expectations for the listener. The second section begins with “depression” and transitions to “anger.” Throughout this section, dissonance is emphasized and helps to suppress a clear and perceivable tonal center. “Depression” functions as a bridge that slowly and gradually simulates a sense of despair. When juxtaposed against the first section, it shows us that consciousness can be related to tonality and unconsciousness to atonality. Although the second section might be considered the lowest emotional point of the work, I attempted to imbue it with a sense of humor that represents the working through of difficulties while never losing faith. The third and final section exposes the idea of acceptance which is achieved by a juxtaposition of sections one (g minor) and three (B major). The ascending third relationship between their two keys suggests the triumphant climb from a depressed state into a state of acceptance that is finally resolved, in the coda, in the key of E major simulating the sense of moving on. The work relies on processes drawn from electronic music in which sound masses are transformed by adding or subtracting discrete variables, or single parameters of sound and time: pitch, rhythm, and dynamics. For example, bars 111-127 contain a rhythmic figure in the piano that slows down and is transformed into a sound-mass. That sound-mass is then orchestrated throughout different instrumental groupings, creating a spatialized musical effect where the phasing of the sound mass from one instrumental group to the next changes the way the listener experiences the piece. Passing the main melody from one instrumental group to another quickly creates a three-dimensional listening space where the listener can experience a change in timbre in addition to the isolation of the harmonic series as the melody passes through each group. Throughout the compositional process I attempted to incorporate the elastic properties of time and space made possible using the tools found in 8-channel electronic music. These tools were incorporated by manipulating both chordal progressions and orchestration as illustrated in the previous paragraph. Such a musical effect spatializes sound by diffusing energy evenly throughout a performance environment. The result is an immersive listening experience, in which sound is generated from specific directions at precise times, different from the standard front and center direction we have come to expect.

京都大学 / 0048 / 新制・論文博士 / 博士(工学) / 乙第13008号 / 論工博第4133号 / 新制||工||1649(附属図書館) / 32936 / (主査)教授 北村 隆行, 教授 北條 正樹, 教授 琵琶 志朗 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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In engineering, materials are often assumed to be homogeneous and isotropic; in actuality, material properties do change with sample direction and location. This variation is due to the anisotropy of the individual grains and their spatial distribution in the material. Currently there is a lack of communication between the design engineer, material scientist, and processor for solving multi-objective/constrained designs. If communication existed between these groups then materials could be designed for applications, instead of the reverse. Microstructure sensitive design introduces a common language, a spectral representation, where both design properties and microstructures are expressed. Using Hill bounds, effective elastic properties are expressed within the spectral representation. For the elastic properties, two FCC materials, copper and nickel, were chosen for computation and to demonstrate how symmetry enters into the methodology. This spectral representation renders properties as hyper-surfaces that translate through a multi-dimensional Fourier space depending on the property value of the hyper-surface. Property closures are generated by condensing the information contained within the multi-dimensional Fourier space into a 2-D representation. This compaction of information is beneficial for a quick determination of property limits for a particular alloy system. The design engineer can now dictate the critical design properties and receive sets of microstructures that satisfy the design objectives.

Mineral carbonation contributes to CO2 reduction, and it may also reduce the cost of mineral processing by improving the mechanical properties of rock/ore. Here, we study and compare the mechanical properties of two minerals, forsterite (Mg2SiO4) and magnesite (MgCO3) using molecular dynamics (MD) simulation. The goal is to understand whether carbonation results in hardness reduction of rock and subsequently comminution energy during the crushing and processing of the ore. We investigated how these materials respond to different physical conditions, such as temperature and strain rate, to understand their behavior under stress. By examining the molecular structure of forsterite and magnesite at temperatures ranging from 300K to 700K and strain rates of 0.001, 0.01, and 0.05ps-1, we observed how they deform when subjected to both tensile and compressive forces. This study has shown that at higher temperatures, both forsterite and magnesite monocrystals undergo deformation more easily under pressure. Forsterite is found relatively hard and shows maximum strength before deformation compared to magnesite. The stiffness of magnesite decreases at elevated temperatures which reduces the energy requirement for the comminution process. We also looked at how pressure and temperature changes affected their elasticity. Ultimately, our findings suggest that magnesite may be more suitable for processes like comminution, which involves breaking down materials, compared to forsterite. This insight into the effects of mineral carbonation on geomaterials contributes to our understanding of how these minerals behave under different conditions and could have implications for various industries. / Master of Science / Mineral carbonation contributes to CO2 reduction, and it may also reduce the cost of mineral processing by improving the mechanical properties of rock/ore. Here, we study and compare the mechanical properties of two minerals, forsterite (Mg2SiO4) and magnesite (MgCO3) using molecular dynamics (MD) simulation. The goal is to understand whether carbonation results in hardness reduction of rock and subsequently comminution energy during the crushing and processing of the ore. We investigated how these materials respond to different physical conditions, such as temperature and strain rate, to understand their behavior under stress. By examining the molecular structure of forsterite and magnesite at temperatures ranging from 300K to 700K and strain rates of 0.001, 0.01, and 0.05ps-1, we observed how they deform when subjected to both tensile and compressive forces. This study has shown that at higher temperatures, both forsterite and magnesite monocrystals undergo deformation more easily under pressure. Forsterite is found relatively hard and shows maximum strength before deformation compared to magnesite. The stiffness of magnesite decreases at elevated temperatures which reduces the energy requirement for the comminution process. We also looked at how pressure and temperature changes affected their elasticity. Ultimately, our findings suggest that magnesite may be more suitable for processes like comminution, which involves breaking down materials, compared to forsterite. This insight into the effects of mineral carbonation on geomaterials contributes to our understanding of how these minerals behave under different conditions and could have implications for various industries.

The present doctoral thesis summarises results of investigation focused on the characterisation of materials involved in Solid Oxide Cell technology. The main topic of investigation was the ceramic cell, also known as MEA. Particular attention was given to the role that bi-material interfaces, co-sintering effects and residual stresses play in the resulting mechanical response. The first main goal was to investigate the effects of the manufacturing process (i.e. layer by layer deposition) on the mechanical response; to enable this investigation, electrode layers were screen-printed one by one on the electrolyte support and experimental tests were performed after every layer deposition. The experimental activity started with the measurement of the elastic characteristics. Both elastic and shear moduli were measured via three different techniques at room and high temperature. Then, uniaxial and biaxial flexural strengths were determined via two loading configurations. The analysis of the elastic and fracture behaviours of the MEA revealed that the addition of layers to the electrolyte has a detrimental effect on the final mechanical response. Elastic characteristics and flexural strength of the electrolyte on the MEA level are sensibly reduced. The reasons behind the weakening effect can be ascribed to the presence and redistribution of residual stresses, changes in the crack initiation site, porosity of layers and pre-cracks formation in the electrode layers. Finally, the coefficients of thermal expansion were evaluated via dilatometry on bulk materials serving as inputs for finite elements analyses supporting experiments and results interpretation. The second most important goal was to assess the influence of operating conditions on the integrity of the MEA. Here interactions of ceramic–metal interfaces within the repetition unit operating at high temperatures and as well at both oxidative and reductive atmospheres were investigated. The elastic and fracture responses of MEA extracted from SOC stacks after several hours of service were analysed. Layer delamination and loss of mechanical strength were observed with increasing operational time. Moreover, SEM observations helped to detect significant microstructural changes of the electrodes (e.g. demixing, coarsening, elemental migration and depletion), which might be responsible for decreased electrochemical performances. All the materials presented in this work are part of SOC stacks produced and commercialised by Sunfire GmbH, which is one of the world leading companies in the field.

<p>The present thesis is concerned to the application of first-principles self-consistent total-energy calculations within the density functional theory on different topics in materials science.</p><p>Crystallographic phase-transitions under high-pressure has been study for TiO2, FeI2, Fe3O4, Ti, the heavy alkali metals Cs and Rb, and C3N4. A new high-pressure polymorph of TiO2 has been discovered, this new polymorph has an orthorhombic OI (Pbca) crystal structure, which is predicted theoretically for the pressure range 50 to 100 GPa. Also, the crystal structures of Cs and Rb metals have been studied under high compressions. Our results confirm the recent high-pressure experimental observations of new complex crystal structures for the Cs-III and Rb-III phases. Thus, it is now certain that the famous isostructural phase transition in Cs is rather a new crystallographic phase transition.</p><p>The elastic properties of the new superconductor MgB2 and Al-doped MgB2 have been investigated. Values of all independent elastic constants (c11, c12, c13, c33, and c55) as well as bulk moduli in the a and c directions (Ba and Bc respectively) are predicted. Our analysis suggests that the high anisotropy of the calculated elastic moduli is a strong indication that MgB2 should be rather brittle. Al doping decreases the elastic anisotropy of MgB2 in the a and c directions, but, it will not change the brittle behaviour of the material considerably.</p><p>The three most relevant battery properties, namely average voltage, energy density and specific energy, as well as the electronic structure of the Li/LixMPO4 systems, where M is either Fe, Mn, or Co have been calculated. The mixing between Fe and Mn in these materials is also examined. Our calculated values for these properties are in good agreement with recent experimental values. Further insight is gained from the electronic density of states of these materials, through which conclusions about the physical properties of the various phases are made.</p><p>The electronic and magnetic properties of the dilute magnetic semiconductor Mn-doped ZnO has been calculated. We have found that for an Mn concentration of 5.6%, the ferromagnetic configuration is energetically stable in comparison to the antiferromgnetic one. A half-metallic electronic structure is calculated by the GGA approximation, where Mn ions are in a divalent state leading to a total magnetic moment of 5 μB per Mn atom.</p>

The present thesis is concerned to the application of first-principles self-consistent total-energy calculations within the density functional theory on different topics in materials science. Crystallographic phase-transitions under high-pressure has been study for TiO2, FeI2, Fe3O4, Ti, the heavy alkali metals Cs and Rb, and C3N4. A new high-pressure polymorph of TiO2 has been discovered, this new polymorph has an orthorhombic OI (Pbca) crystal structure, which is predicted theoretically for the pressure range 50 to 100 GPa. Also, the crystal structures of Cs and Rb metals have been studied under high compressions. Our results confirm the recent high-pressure experimental observations of new complex crystal structures for the Cs-III and Rb-III phases. Thus, it is now certain that the famous isostructural phase transition in Cs is rather a new crystallographic phase transition. The elastic properties of the new superconductor MgB2 and Al-doped MgB2 have been investigated. Values of all independent elastic constants (c11, c12, c13, c33, and c55) as well as bulk moduli in the a and c directions (Ba and Bc respectively) are predicted. Our analysis suggests that the high anisotropy of the calculated elastic moduli is a strong indication that MgB2 should be rather brittle. Al doping decreases the elastic anisotropy of MgB2 in the a and c directions, but, it will not change the brittle behaviour of the material considerably. The three most relevant battery properties, namely average voltage, energy density and specific energy, as well as the electronic structure of the Li/LixMPO4 systems, where M is either Fe, Mn, or Co have been calculated. The mixing between Fe and Mn in these materials is also examined. Our calculated values for these properties are in good agreement with recent experimental values. Further insight is gained from the electronic density of states of these materials, through which conclusions about the physical properties of the various phases are made. The electronic and magnetic properties of the dilute magnetic semiconductor Mn-doped ZnO has been calculated. We have found that for an Mn concentration of 5.6%, the ferromagnetic configuration is energetically stable in comparison to the antiferromgnetic one. A half-metallic electronic structure is calculated by the GGA approximation, where Mn ions are in a divalent state leading to a total magnetic moment of 5 μB per Mn atom.