In a recent study, an environment-friendly material, corrugated cardboard, was used as a building block for the vibration isolator with a preliminary study. The present thesis was motivated to advance technology for improving the design of such a corrugated cardboard vibration isolator with a focus on the modeling of its stiffness and damping. In particular, this study has performed the following works: (1) improving the FE (finite element) model of the stiffness of the corrugated cardboards by more accurately identifying the material parameters in the cardboard material constitutive equation; (2) analyzing the effect of the error in geometry of the corrugated cardboards in the FE model; (3) developing the Rayleigh damping model of the corrugated cardboards and evaluating its accuracy. Several conclusions were drawn from this study: (1) the parameter identification procedure based on the inverse analysis is feasible for improving the accuracy of the model of the stiffness of the cardboard. (2) The FE model of the cardboards with a greater in-plane geometrical deflection has less vertical compressive stiffness. The geometrical deflections of the corrugated cardboards also change the condition of the contact friction stress and the compressive deformation. (3) Rayleigh damping model is accurate enough for calculating the damping of the corrugated cardboards. The contributions of the thesis include: (1) provision of a more accurate model for the compressive stiffness the corrugated cardboards, (2) finding that the friction between the cardboard and the vibrator and the geometrical error of the cardboards have a significant influence over the accuracy of the FE model, (3) finding that in practice the foregoing influence can significantly degraded the performance of the cardboards as a vibrator isolator, and (4) provision of a model for the compressive damping of the corrugated cardboards.

The oxidation behavior of model binary and ternary alloys in supercritical water (SCW) was examined. Binary alloys contained 9 or 14 at% Cr. Ternary alloys had 1.5 at% of one of the following elements: Si, Al, V, Mn or Ti. Samples with different surface finishes were exposed to SCW for up to 500 hours. The oxidized samples were characterized using gravimetry, SEM, HRTEM and EDX. After exposure, a uniform double layer oxide with outwardly grown magnetite inwardly grown Fe-Cr mixed oxide was detected on most of samples. Alloys contains 14 at% Cr or/and 1.5 at% Si showed a mixed oxidation mode, where relatively thick double layer oxides coexisted with thin protective oxide. The coverage with the thin oxide increased with the increase of deformation and/or Cr and/or Si content. A 20 nm thick Si-enriched layer was detected at such alloy/oxide interfaces. This behavior is very similar to “third element effect”.

The oxidation behavior of model binary and ternary alloys in supercritical water (SCW) was examined. Binary alloys contained 9 or 14 at% Cr. Ternary alloys had 1.5 at% of one of the following elements: Si, Al, V, Mn or Ti. Samples with different surface finishes were exposed to SCW for up to 500 hours. The oxidized samples were characterized using gravimetry, SEM, HRTEM and EDX. After exposure, a uniform double layer oxide with outwardly grown magnetite inwardly grown Fe-Cr mixed oxide was detected on most of samples. Alloys contains 14 at% Cr or/and 1.5 at% Si showed a mixed oxidation mode, where relatively thick double layer oxides coexisted with thin protective oxide. The coverage with the thin oxide increased with the increase of deformation and/or Cr and/or Si content. A 20 nm thick Si-enriched layer was detected at such alloy/oxide interfaces. This behavior is very similar to “third element effect”.

The growing interest in increasing the wear resistance and hardness of surfaces that are in contact with abrasives or corrosive materials has inspired the development of several processes for creating protective coatings. In-situ laser cladding is one of the most promising of these processes. It enables the formation of a uniform coating by melting powder to form the desired composition from a pure powder component. In this research, pure Ti, graphite, and Fe are used for in-situ laser cladding on a steel substrate to form an Fe-TiC metal matrix composite (MMC). The effect of laser parameters on both the quality of the bonding and morphology of the in-situ-formed TiC iron-based composite clad are investigated. Results show that laser parameters play a crucial role in determining the clad quality and clad microstructure. Two combined parameters, effective energy and powder deposition density, are used to study the effect of laser parameters (i.e., laser power, scan speed and powder feed rate) on the clad properties. While results indicate that combined parameters help to determine the quality limit, laser process parameters need to be taken into account in order to study the clad microstructure. To increase the clad hardness and TiC volume fraction, C:Ti atomic ratio should increase from 45:55 to 55:45, and Fe percentages in the powder composition should decrease from 70 wt% to the 10 wt%. By varying the powder composition, a change in TiC morphology, clad microstructure and clad hardness occurs. The dilution effect is also considered in the interpretation of results. In order to estimate wear resistance, the ASTM G65-A procedure was selected to perform tests on various clad compositions. An increased wear resistance is seen when the volume fraction of TiC is increased.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 121-127).

This thesis presents experimental studies of the electronic and magnetic properties of several iron-based unconventional superconductors, primarily using the techniques of magnetotransport and torque magnetometry in high magnetic fields and synchrotron-based angle-resolved photo-emission spectroscopy (ARPES). Superconductivity in the iron-based superconductors is always found in proximity to a magnetic phase, and the details of the electronic structure and Fermi surface are also important in determining the strength of interactions, and ultimately superconductivity. This motivates the experimental studies of electronic, magnetic and superconducting properties of Fe-based superconductors presented in this thesis. First, quantum oscillation measurements using high-field torque magnetometry are used to provide a partial determination of the Fermi surface of superconducting LiFeAs. The data are compared with density functional theory calculations, finding strong mass enhancements on the observed electron bands, however the hole bands are not observed. A large portion of this thesis concerns experiments on FeSe, which uniquely has a structural transition but is not magnetically ordered at any temperature. High field magnetotransport measurements show quantum oscillations, revealing small quasi-two dimensional Fermi surfaces, and it is argued that both hole and electron pockets are observed. The low-temperature Fermi surface consisting of one hole pocket and two electron pockets is also deduced from low-field magnetotransport. ARPES studies show that both hole and electron pockets undergo a significant elongation when cooling through the structural transition at ~90 K, interpreted as the result of orbital order. Measurements of the resistivity anisotropy above the structural transition are used to show that the structural distortion is electronically-driven. By combining these data sets, a complete picture of the symmetry-broken electronic structure of FeSe is constructed. The final chapter concerns another iron-based superconductor with a more complex crystal structure, the so-called ``10-3-8" phase, and in particular finds an unusual field-induced magnetic transition.

Polymer matrix composites (PMCs) offer several advantages compared to traditional metallic counterparts when employed in high-performance products that need to be lightweight, yet strong enough to sustain harsh loading conditions - such as aerospace components and protective structures in military applications- armours, helmets, and fabrications retrofitted to transport vehicles and bunkers. These are often subjected to highly dynamic loading conditions under blast and ballistic impacts. Severe impact energy involved in these dynamic loading events can initiate discrete damage modes in PMCs such as matrix cracking, matrix splitting, delamination, fibre-matrix debonding, fibre micro-buckling and fibre pull-out. Interaction of these damage modes can severely reduce the load carrying capacity of such structures. This needs to be understood to design structures with improved resistance to such loading.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciencias Humanas / Made available in DSpace on 2012-10-16T07:52:23Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T18:55:42Z : No. of bitstreams: 1 98006.pdf: 3177346 bytes, checksum: ac0cea6e1b5e8b5a2fb9f7bde86c6915 (MD5) / Neste trabalho, analisam-se as representações de saúde, doença e cura de um grupo de adeptos da doutrina do Santo Daime de Florianópolis. Considerando a importância outorgada por estes indivíduos ao fenômeno da "cura espiritual", coloca-se especial ênfase neste tema. Este grupo consome ritualmente uma bebida, o "Santo Daime", que é originada dos grupos indígenas amazônicos, sendo conhecida por estas culturas como ayahuasca, caapi ou iage. O Santo Daime é considerado uma bebida "sagrada", atribuindo-se-lhe poderes terapêuticos, fundamentalmente de "cura espiritual". Esta substância possui um agente psicodélico, a DMT. Sendo que a psicoterapia psicodélica utilizou estas substâncias como agentes de "abertura espiritual" ou de "emergência espiritual", para curar transtornos neuróticos e psicossomáticos, aborda-se o estudo do potencial "curativo" do Santo Daime, utilizando a teoria elaborada por um dos principais pesquisadores da psicoterapia psicodélica, Stanislav Grof. As narrativas de experiências rituais daimistas são analisadas usando o modelo de Grof. Nestes relatos encontram-se os quatro domínios do inconsciente descritos por este autor. Entretanto, dentro do grupo existem significados peculiares em relação às experiências provenientes destes diferentes domínios, sendo tais significados também essenciais no processamento da "cura espiritual".

abstract: Soft magnetic alloys play a significant role for magnetic recording applications and highly sensitivity magnetic field sensors. In order to sustain the magnetic areal density growth, development of new synthesis techniques and materials is necessary. In this work, the effect of oxygen incorporation during electrodeposition of CoFe alloys on magnetic properties, magnetoresistance and structural properties has been studied. Understanding the magnetic properties often required knowledge of oxygen distribution and structural properties of the grown films. Transmission electron microscopy (TEM) was a powerful tool in this study to correlate the oxygen-distribution nanostructure to the magnetic properties of deposited films. Off-axis electron holography in TEM was used to measure magnetic domain wall width in the deposited films. Elemental depth profiles of Fe, Co, O were investigated by secondary ion mass spectroscopy (SIMS). Magnetic properties have been determined by superconducting quantum interference device (SQUID) measurements. Oxygen content in the CoFe deposited films was controlled by electrolyte composition. Films were deposited on Si 100 substrates and on other substrates such as Cu and Al. However, a good film quality was achieved on Si substrate. Electron energy loss and x-ray spectroscopies showed that the low oxygen films contained intragranular Fe2+ oxide (FeO) particles and that the high oxygen films contained intergranular Fe3+ (Fe2O3) along grain boundaries. The films with oxide present at the grain boundary had significantly increased coercivity, magnetoresistance and reduced saturation magnetization relative to the lower oxygen content films with intragranular oxide. The differences in magnetic properties between low oxygen and high oxygen concentration films were attributed to stronger mobile domain wall interactions with the grain boundary oxide layers. The very high magnetoresistance values were achieved for magnetic devices with nanocontact dimension < 100 nm and oxide incorporation in this nanoconfined geometry. The content of oxide phase in nanocontact was controlled by concentration of the Fe3+ ions in the electrodeposition solution. Magnetic device integrity was improved by varying amount of additive into plating solution. These results indicated that electrodeposited CoFe nanocontact is a novel class of materials with large application for magnetic field sensors. / Dissertation/Thesis / Ph.D. Materials Science and Engineering 2012

Clubfoot is one of the most common pathologies of the foot affecting 1 in 1000 newborn babies according to statistics. The first treatment approach is by using conventional procedures, such as plaster and cast, and, the literature reports a range of failures causing relapse. Patients with severe or relapsed cases or patients that are treated later in life may require unconventional procedures to provide correction. In order to increase the success rate after the correction, it is necessary to: a)perform analyses to improve the current treatments and b) investigate the tissues involved in this pathology in order to have a better understanding of clubfoot to develop future treatments. The Ilizarov fixator has been shown to be a good alternative for complex and relapsed cases. However, there are no numerical nor experimental studies to: a) improve the efficiency of the frame deployment for clubfoot, b) provide guidance on the right adjustment procedures, and c) understand the mechanical behaviour of the frame applied to clubfoot. This makes the adjustments fully dependent on the surgeon's experience instead of systematic guidelines/procedures. This results in configurations that induce stresses in the fixator that are transferred to the tissues and leading to a reduction in the success rate. Furthermore, the literature on the correction of clubfoot in babies and the role of the tissues in babies' feet during the correction is limited. Therefore, the aim of the thesis is to analyse the relationship between the adjustments of the connectors and the displacements of the fixator rods, on the one hand, and the stress-strain induced in the rods and fixator, on the other hand. This is achieved by means of a finite element analysis of the stress-strain distributions in the fixator components. The predicted stresses are used for the identification of the components that should be adjusted in the fixator to prevent them from failure. The findings and results in the thesis will enable surgeons to understand better the mechanical behaviour of the Ilizarov frame in clubfoot, and they will facilitate the establishment of a functional range of the fixator in order to improve the current procedures. Another aim is to investigate the mechanical behaviour of one of the most affected bones during the correction of clubfoot in babies, namely the talus. The literature reports a change of shape in the talus during clubfoot correction using conventional procedures. This can result in a change of the stress distribution in the foot tissues during gait in latter stages of life leading to different pathologies. This clearly shows the importance of investigating the mechanical behaviour of the talus. This is the first numerical study to investigate the right adjustment procedures of the frame for clubfoot. It is expected that the findings of this research contribute to the improvement of the current corrective procedures based on the use of the Ilizarov frame and to improve the understanding of clubfoot in babies.