Leung Ping-chung. / Thesis (D.Sc.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references.

Or Pui Ching. / Thesis submitted in: December 1999. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 174-201). / Abstracts in English and Chinese. / acknowledgement --- p.i / abstract (english version) --- p.ii / abstract (chinese version) --- p.vii / table of contents --- p.xi / abbreviations --- p.xvi / list of tables --- p.xviii / list of figures --- p.xxii / Chapter chapter 1. --- introduction --- p.1 / Chapter chapter 2. --- literature review --- p.3 / Chapter 2.1. --- Bone structure --- p.3 / Chapter 2.1.1. --- Composition --- p.3 / Chapter 2.1.2. --- Cortical and Trabecular bone --- p.3 / Chapter 2.2. --- Bone Remodeling --- p.4 / Chapter 2.3. --- Bone Mass --- p.5 / Chapter 2.3.1. --- Peak Bone Mass --- p.5 / Chapter 2.3.1.1. --- Racial and Genetic Factors --- p.5 / Chapter 2.3.1.2. --- Gonadal Factors --- p.6 / Chapter 2.3.1.3. --- Nutrition Factors --- p.6 / Chapter 2.3.1.4. --- Exercise and Physical Activity --- p.7 / Chapter 2.3.2. --- Bone Loss --- p.7 / Chapter 2.3.2.1. --- Determinants of Osteoporotic Bone Loss --- p.7 / Chapter 2.3.2.2. --- Estrogen Deficiency --- p.8 / Chapter 2.3.2.3. --- Dietary Calcium deficiency and Vitamin D deficiency --- p.8 / Chapter 2.3.2.4. --- Physical Activity --- p.9 / Chapter 2.3.2.5. --- Alcoholism and Smoking --- p.9 / Chapter 2.3.2.6. --- Disease-specific Osteoporosis --- p.9 / Chapter 2.3.2.7. --- Drug-induced Osteoporosis --- p.10 / Chapter 2.3.3. --- Bone Mass and Fracture Risk --- p.11 / Chapter 2.4. --- Clinical Presentation of Osteoporosis --- p.12 / Chapter 2.4.1. --- Vertebral Fractures --- p.12 / Chapter 2.4.1.1. --- Radiological Aspects of Vertebral Fracture --- p.13 / Chapter 2.4.1.1.1. --- Changes in Trabecular Pattern --- p.13 / Chapter 2.4.1.1.2. --- Changes in Shape of the Vertebral bodies --- p.13 / Chapter 2.4.1.1.3. --- Changes of Intervertebral Discs --- p.14 / Chapter 2.4.1.2. --- Back Pain --- p.15 / Chapter 2.4.2. --- Hip Fractures --- p.15 / Chapter 2.4.3. --- Quality of Life --- p.16 / Chapter 2.5. --- Treatment of Established Osteoporosis --- p.18 / Chapter 2.5.1. --- Pain Relief --- p.18 / Chapter 2.5.2. --- Drug Therapy --- p.19 / Chapter 2.5.2.1. --- Calcium Supplement --- p.19 / Chapter 2.5.2.2. --- Vitamin D --- p.20 / Chapter 2.5.2.3. --- Estrogen --- p.21 / Chapter 2.5.2.4. --- Fluorides --- p.22 / Chapter 2.5.2.5. --- Calcitonin --- p.23 / Chapter 2.5.2.6. --- Bisphosphonates --- p.24 / Chapter 2.5.2.6.1. --- Physicochemical effects --- p.27 / Chapter 2.5.2.6.2. --- Mechanisms --- p.27 / Chapter 2.5.2.6.3. --- Therapeutic Use --- p.27 / Chapter 2.5.2.6.4. --- Side effects --- p.29 / Chapter 2.5.2.6.5. --- Alendronate --- p.30 / Chapter 2.5.2.7. --- Summary of drug treatment --- p.33 / Chapter 2.6. --- Diagnostic Methods of Osteoporosis --- p.40 / Chapter 2.6.1. --- Biochemical Markers of Bone Metabolism in Osteoporosis --- p.40 / Chapter 2.6.1.1. --- Bone Formation Markers --- p.41 / Chapter 2.6.1.1.1. --- Bone-specific Alkaline Phosphatase (bALP) --- p.41 / Chapter 2.6.1.2. --- Bone Resorption Markers --- p.42 / Chapter 2.6.1.2.1. --- Deoxypyridinoline (Dpd) --- p.43 / Chapter 2.6.2. --- Bone Densitometry --- p.45 / Chapter 2.6.2.1. --- Dual Energy X-ray Absorptiometry (DEXA) --- p.45 / Chapter 2.6.2.2. --- Peripheral Quatitative Computed Tomography (pQCT) --- p.47 / Chapter 2.6.2.3. --- Quantitative Ultrasound (QUS) --- p.48 / Chapter 2.6.3. --- Summary of Diagnostic Methods --- p.49 / Chapter chapter 3. --- methodology --- p.50 / Chapter 3.1. --- Study on Vertebral Structures --- p.51 / Chapter 3.1.1. --- Procedures --- p.51 / Chapter 3.1.2. --- Data analysis --- p.53 / Chapter 3.2. --- Alendronate Treatment --- p.54 / Chapter 3.2.1. --- Subject Selection --- p.54 / Chapter 3.2.2. --- Study design and drug administration --- p.55 / Chapter 3.2.3. --- Bone Densitometry --- p.56 / Chapter 3.2.3.1. --- Dual Energy X-ray absorptiometry --- p.56 / Chapter 3.2.3.2. --- Peripheral Quantitative Computed Tomography (pQCT) --- p.58 / Chapter 3.2.4. --- Biochemical Markers --- p.63 / Chapter 3.2.4.1. --- Bone formation marker --- p.63 / Chapter 3.2.4.2. --- Bone resorption marker --- p.64 / Chapter 3.2.5. --- Quality of Life --- p.65 / Chapter 3.2.6. --- New fracture assessment --- p.66 / Chapter 3.2.7. --- Statistical analysis --- p.67 / Chapter 3.3. --- Proximal femur fracture study --- p.68 / Chapter 3.3.1. --- Subject and study design --- p.69 / Chapter 3.3.2. --- Statistical analysis --- p.70 / Chapter chapter 4. --- results of study on vertebral structures --- p.71 / Chapter 4.1. --- Results of morphological change of vertebral bodes in osteoporotic patients --- p.71 / Chapter 4.2. --- Morphological changes of intervertebral discs --- p.71 / Chapter 4.3. --- Correlation between morphological changes of vertebrae and bulging ratio --- p.72 / Chapter chapter 5. --- results of alendronate study --- p.76 / Chapter 5.1. --- Baseline measurement --- p.76 / Chapter 5.1.1. --- Demographic characteristics --- p.76 / Chapter 5.1.2. --- Reasons for admission --- p.77 / Chapter 5.1.3. --- Social support --- p.77 / Chapter 5.1.4. --- Number of vertebral fracture(s) --- p.78 / Chapter 5.1.5. --- BMD measurement (Baseline) --- p.79 / Chapter 5.1.5.1. --- BMD of Lumbar spine and Hip (measured by DEXA) --- p.79 / Chapter 5.1.5.2. --- BMD of distal tibia and radius measured by pQCT --- p.80 / Chapter 5.1.6. --- Biochemical Markers (Bone formation and resorption) --- p.86 / Chapter 5.2. --- After treatment --- p.88 / Chapter 5.2.1. --- Bone mineral density measurement (measured by DEXA) --- p.90 / Chapter 5.2.1.1. --- Lumbar spine --- p.90 / Chapter 5.2.1.2. --- Femoral Neck --- p.93 / Chapter 5.2.1.3. --- Trochanter --- p.95 / Chapter 5.2.1.4. --- Ward's Triangle --- p.98 / Chapter 5.2.1.5. --- Summary --- p.101 / Chapter 5.2.2. --- Bone Mineral Density measured by pQCT --- p.103 / Chapter 5.2.2.1. --- Distal Radius (Program 1) --- p.103 / Chapter 5.2.2.1.1. --- BMD change of D50 --- p.103 / Chapter 5.2.2.1.2. --- BMD changes of D100 --- p.106 / Chapter 5.2.2.1.3. --- BMD change of P100 --- p.108 / Chapter 5.2.2.2. --- Distal Radius (Program 2) --- p.111 / Chapter 5.2.2.2.1. --- BMD change of pure trabecular bone --- p.112 / Chapter 5.2.2.2.2. --- BMD changes of pure cortical bone --- p.114 / Chapter 5.2.2.3. --- Distal Tibia (Program 1) --- p.118 / Chapter 5.2.2.3.1. --- BMD changes of D50 --- p.118 / Chapter 5.2.2.3.2. --- BMD changes of D100 --- p.121 / Chapter 5.2.2.3.3. --- BMD changes of P100 --- p.124 / Chapter 5.2.2.4. --- Distal Tibia (Program 2) --- p.128 / Chapter 5.2.2.4.1. --- BMD changes of pure trabecular bone --- p.128 / Chapter 5.2.2.4.2. --- BMD changes of pure cortical bone --- p.131 / Chapter 5.2.3. --- Bone turnover --- p.135 / Chapter 5.2.3.1. --- Bone Resorption Marker (urinary Deoxypyridinoline) --- p.135 / Chapter 5.2.3.2. --- Bone Formation Marker (Bone Specific Alkaline Phosphatase) --- p.137 / Chapter 5.2.4. --- Quality of Life (QOL) --- p.139 / Chapter 5.2.5. --- Oswestry Disability Index (ODI) --- p.139 / Chapter 5.2.6. --- Pain --- p.141 / Chapter 5.2.6.1. --- Pain frequency --- p.141 / Chapter 5.2.6.2. --- Night Pain --- p.142 / Chapter 5.2.6.3. --- Administration of pain relief drugs --- p.143 / Chapter 5.2.7. --- Activity of daily living --- p.144 / Chapter 5.2.8. --- Prevention of new vertebral fracture(s) --- p.146 / Chapter 5.2.9. --- Safety and Tolerability --- p.147 / Chapter chapter 6. --- results on proximal femoral fractures study --- p.149 / Chapter 6.1. --- Epidemiological study on proximal femoral fractures --- p.149 / Chapter 6.2. --- The role of ultrasound equipment in the assessment osteoporosis in patients with proximal femoral fractures --- p.154 / Chapter 6.3. --- Summary --- p.155 / Chapter chapter 7. --- discussion --- p.156 / Chapter 7.1. --- The study on vertebral structures --- p.156 / Chapter 7.1.1. --- Changes in Shape of Vertebral Bodies --- p.156 / Chapter 7.1.2. --- Changes of Interevertbral Discs --- p.157 / Chapter 7.2. --- Alendronate treatment on Chinese elderly women with Osteoporotic vertebral fracture --- p.158 / Chapter 7.2.1. --- The Effect of Alendronate on BMD of Lumbar Spine --- p.159 / Chapter 7.2.2. --- The Effects of Alendronate on BMD of Proximal Femur --- p.159 / Chapter 7.2.3. --- The Effects of Alendronate on the BMD of Trabecular and Cortical Bone in the Distal Radius and Distal Tibia --- p.160 / Chapter 7.2.4. --- The Effects of Calcium Supplementation in the study --- p.162 / Chapter 7.2.5. --- The Effect of alendronate on Biochemical Turnover --- p.162 / Chapter 7.2.6. --- The Efficacy of Alendronate on Prevention of New Fractures --- p.163 / Chapter 7.2.7. --- The Effect of Alendronate on Quality of Life --- p.164 / Chapter 7.2.8. --- Adverse Effects of Alendronate --- p.165 / Chapter 7.3. --- Proximal Femur Fracture Study --- p.165 / Chapter chapter 8. --- conclusion --- p.168 / bibliography --- p.174 / epilogue --- p.202 / appendix --- p.xxv

Les roches vulcanogéniques de la Mine de Seival appartiennent à la Formation Hilário du Bassin de Camaquã, d’âge Néoprotérozoique. Ces roches contiennent six mines inactives avec diverses prospections de cuivre–argent. Les minéralisations semblent associées à un contrôle structurel intense du régime ruptile. La compréhension de la transformation chimique de l’hydrothermalisme associé aux paléo-contraintes est assez faible dans la région. Nous proposons de caractériser la chimie des minéraux des phases magmatiques, tardi–magmatiques et hydrothermales ainsi que de comprendre les contraintes structurales et la géochimie des veines tardives de barytine et calcite. Pour ce faire, nous avons effectué des analyses minéralogiques, et chimiques des phases magmatiques et d’altération. La chimie minérale associée à la modélisation thermodynamique a permis de caractériser l’altération comme tardi– magmatique. L’albitisation (650 à 350 °C) s’est produite en association avec une chloritisation (312 à 120 °C) et avec de la pyrite et de la chalcopyrite. Les températures les plus basses (150 à 50 °C) ont été reliées à la formation de smectite et d’inter-stratifié de chlorite/smectite et avec de la chalcocite–covellite, chalcocite–bornite ou barytine. Nous effectuons les analyses structurales des mesures de cinématique et de la direction des failles/fractures. L’analyse structurale a montré trois contraintes principales survenant dans la Mine Seival et dans le District Minier de Lavras do Sul : compression NW–SW ; compression NE–SW ; distension ENE–SWS. La contrainte NW–SE est la principale direction de contrainte associée à la minéralisation et aux filons minéralisés dans ces deux régions. / The volcanogenic rocks of the Seival Mine belong to Hilário Formation from Camaquã Basin, with ages Neoproterozoic. These rocks contain six inactive mines with various prospects of copper-silver. Mineralization are associated with intense structural control in brittle regime. Chemical transformation of hydrothermal alteration associated with paleostress is not very well understood in the region. We propose a characterization of mineral chemistry of the magmatic phases, tardi–magmatic and hydrothermal as well as understand the paleostress and geochemistry of late veins. For this, we realized analyses of mineral chemistry of magmatic and alteration phase. Mineral chemistry coupled with thermodynamic modeling allowed to characterize the alteration as tardi–magmatic. The albitization (650 to 350 °C) occurred in association with chloritization (312 to 120 °C), and with pyrite and chalcopyrite. The lowest temperatures (150 to 50 °C) were related to formation of smectite and interlayered chlorite/smectite, and with chalcocite–covellite, chalcocite–bornite or barite. We perform structural analyzes through kinematic measures and failure/fracture directions. The analysis on faults, fractures and mineralization showed three main stresses occurring in the Seival Mine and Lavras do Sul Mining District: NW–SE compression; NE–SW compression; ENE–SWS distension. The NW–SE paleostress is the main effort related to the dikes and mineralization in both areas.

Aujourd’hui, l’un des principaux défis dans l’industrie pétrolière, et particulièrement dans le domaine de l’exploration, est l’exploitation des nouvelles ressources dans des zones structuralement complexes.Nous savons que la géométrie et le glissement le long des failles actives modifie la distribution locale des contraintes. La connaissance du champ de contrainte perturbé actuel est importante pour l’étude des tremblements de Terre, pour la planification de forages ainsi que pour la prédiction de la fracturation induite par l’hydro-fracturation et la prédiction de la réactivation des fractures. Les contraintes perturbées passées, quant à elles sont responsables du développement des fractures naturelles (préexistantes). La détection et la modélisation de celles-ci sont essentielles tant dans le domaine pétrolier (migration et piégeage des fluides) pour une exploitation efficace et à moindre coût des réserves naturelles.Comprendre et quantifier le développement spatial et temporel de ces contraintes a un impact économique non négligeable. L'analyse des paléo-contraintes a été introduite dans un premier temps par Anderson (1905 & 1942) de manière intuitive, puis dans le milieu du siècle dernier, Wallace (1951) et Bott ( 1959) proposèrent les simples postulats que le champ de contrainte est homogène et que la direction du rejet est parallèle à la traction projetée sur le plan de faille. Beaucoup de méthodes d’inversion de contraintes reposent aujourd’hui sur ce principe.Afin d’étudier la validité de l’hypothèse Wallace et Bott, une comparaison avec les vecteurs de glissement générés à partir de modèles numériques (BEM) est effectuée. En testant l’influence de multiples paramètres (géométrie, contraintes au limites du modèle, friction, coefficient de poisson, demi-espace, pression de fluide dans la faille), il est montré que les failles à géométries complexes soumises à certaines contraintes aux limites peuvent engendrer des vecteurs glissements présentant des écarts important avec les la plus grande contraintes cisaillantes résolue sur le plan de faille. A l’inverse, la présence d’une forte friction de glissement permet, dans certaines conditions, de valider l’hypothèse de Wallace et Bott. On s’attache ensuite à comparer les résultats des inversions de contraintes basées sur l’hypothèse de Wallace et Bott (appelé méthode d’inversion classique de contraintes) avec une méthode géomécanique. Pour cela, une faille à géométrie complexe est utilisée dans une étude de sensibilité (contraintes aux limites, friction, échantillonnage) permettant d’analyser l’incertitude des résultats des deux méthodes d’inversion. Cette analyse est ensuite confrontée à l’étude d’un cas de terrain, montrant les avantages et inconvénients des méthodes d’inversions classiques de contraintes.Un des principaux défis de l’industrie pétrolière est l’exploitation des ressources des zones structuralement complexes telles que les réservoirs naturellement fracturés. Connaitre l’état de contraintes hétérogène passé permet d’optimiser la modélisation de ces fractures naturelles. Etant donné que les glissements sur les failles sont difficiles à observer dans les réservoirs pétroliers, les données de d’orientation de fractures (joints, failles, stylolites) sont naturellement prises en compte lors de l’inversion des contraintes. On montre, en utilisant divers exemples de terrain et d’industrie, que dans de tels cas, l’utilisation d’inversions basée sur la mécanique est beaucoup plus appropriée. Cependant, il est parfois difficile de déterminer le type cinématique de fracture observée le long des puits, et très souvent, les zones étudiées ont subi une tectonique polyphasée. La dernière partie vise donc à résoudre le problème des données de types cinématiques non identifiables (joints, failles, stylolites…) et étend parallèlement l’inversion mécanique des contraintes à la séparation de phases tectoniques. / Today, one of the main challenges in the oil industry, especially during the exploration phase, is the exploitation of new resources in structurally complex areas such as naturally fractured reservoirs, salt diapirs, mountain ranges, and unconventional reservoirs.We know that the geometry and sliding along active faults modifies the local stress distribution. Knowing the present day perturbed stress field is important for the study of earthquakes, for the planning of the borehole drilling and stability as well as for the prediction of fractures induced by hydro-fracturing and reactivation of natural fractures. In the other side, perturbed paleostress are responsible for the development of (pre-existing) natural fractures. The detection and modeling of the latter, are essential both in the oil industry (migration and trapping of fluids) for a cost efficient recovery of natural reserves.Understanding and quantifying the spatial and temporal development of the stress distribution has a significant economic and environmental impact. The analysis of paleo-constraints was intuitively introduced first by Anderson (1905 & 1942), then in the middle of the last century, Wallace (1951) and Bott (1959) proposed the simple hypothesis that (i) The stress field is homogeneous in space and constant in time, and that (ii) the slip direction is parallel to the traction projected on the fault plane which gives the direction of the shear stress. Many stress inversion methods are based on this hypothesis while recent studies raise doubts as to their compatibility with rock mechanics.In order to investigate the validity of the Wallace and Bott hypothesis, a comparison with vectors of slip generated with numerical models (BEM) is performed. By testing the influence of multiple parameters (geometry, boundary conditions, friction, Poisson’s coefficient , half-space, fault fluid pressure), it is shown that the complex geometry faults subject to specific boundary conditions can yield slip vectors with significant discrepancies with the maximum shear stress resolved on the fault plane. Conversely, the presence of a high sliding friction, allows under certain conditions, to validate the hypothesis of Wallace and Bott.We then focus on the task to compare the results of stress inversions based on the assumption of Wallace and Bott (called classical stress inversion methods) to a geomechanical method. For this, a complex fault geometry is used in a sensitivity analysis (boundary conditions, friction, sampling) to evaluate the uncertainty of the results of the two inversion methods. This analysis is then compared to a case study, Chimney Rock (Utah, USA), showing the advantages and disadvantages of the classical stress inversion methods.One of the main challenges of the oil industry is the exploitation of resource in structurally complex oil fields such as naturally fractured reservoirs. Knowing the heterogeneous paleostress allows to optimize the modeling of these natural fractures. Since slip on faults is hardly observed in petroleum reservoirs, fracture orientation data (joints, faults, stylolites) are naturally taken into account during the inversion of stresses. It is shown, using various field and industry examples, that in such cases the use of mechanical stress inversions is much more appropriate.However, it is sometimes difficult to determine the fracture kinematics observed along wellbores, and very often the studied regions underwent multiple tectonic phases. The final section aims to address the problem of data with unknown kinematic (joints, faults, stylolites ...) and expends the mechanical stress inversion to the separation of tectonic phases.

Made available in DSpace on 2014-12-17T15:43:48Z (GMT). No. of bitstreams: 1 KerlisonPO_DISSERT.pdf: 1641521 bytes, checksum: 5f1078757c465e02ee64ce8aff96f794 (MD5) Previous issue date: 2012-12-18 / The aim of this study was to comparatively evaluate the mechanical strength of squared and rectangular 2.0 mm system miniplates comparing them to the standard configuration with 2 straight miniplates in stabilizing fractures in the anterior mandible. Ninety synthetic polyurethane mandible replicas were used in mechanical test. The samples were divided into six groups of three different methods for fixation. Groups 1, 2 and 3 showed complete fractures in symphysis, characterized by a linear separation between the medial incisor, and groups 4, 5 and 6 showed complete fractures in parasymphysis with oblique design. Groups 1 and 4 were represented by the standard technique with two straight miniplates parallel to each other. Groups 2 and 5 were stabilized by squared miniplates and groups 3 and 6 were fixed by rectangular design. Each group was subjected to a mechanical test at a displacement speed of 10 mm/min on a universal testing machine, receiving linear vertical load on the region of the left first molar. The values of the maximum load and when displacements reached 5 mm were obtained and statistically analyzed by calculating the confidence interval of 95%. Fixation systems using squared (G2) and rectangular (G3) miniplates obtained similar results. No statistically significant differences with respect to the maximum load and the load at 5 mm displacement were found when compared to standard method in symphyseal fractures (G1). In parasymphysis the fixation method using squared miniplates (G5) obtained results without significant differences regarding the maximum load and the load at 5 mm when compared to the standard configuration (G4). The fixation method using rectangular miniplates (G6) showed inferior results which were statistically significant when compared to the standard configuration (G4) for parasymphysis fractures. The mechanical behavior of the fixation methods was similar, except when rectangular miniplates were used. The fixation methods showed better results with statistical significance in symphyseal fractures / O prop?sito deste estudo foi avaliar comparativamente a resist?ncia mec?nica de miniplacas quadradas e retangulares do sistema 2.0 mm, comparando-as ? configura??o padr?o, com 2 miniplacas retas, na estabiliza??o de fraturas na regi?o anterior de mand?bula. Noventa r?plicas de mand?bulas de poliuretano foram utilizadas no ensaio mec?nico. As amostras foram divididas em 6 grupos com 3 m?todos de fixa??o do sistema 2.0 mm. Os grupos 1, 2 e 3 apresentavam fraturas sinfis?rias completas, caracterizadas pela separa??o linear entre os incisivos mediais, e os grupos 4, 5 e 6 apresentavam fraturas parassinfis?rias completas com desenho obl?quo. Os grupos 1 e 4 foram representados pelo m?todo padr?o, com 2 miniplacas retas, dispostas paralelamente entre si. Os grupos 2 e 5 tiveram as mand?bulas estabilizadas por meio de miniplacas quadradas e os grupos 3 e 6, pelas retangulares. Cada grupo foi submetido a um teste mec?nico realizado por meio de uma m?quina de ensaio universal, na velocidade de 10mm/minuto, recebendo carga vertical linear na regi?o de primeiro molar esquerdo. Os valores da carga m?xima e da carga com deslocamento pr?-estabelecido em 5 mm foram obtidos e submetidos ? an?lise estat?stica a partir do c?lculo do intervalo de confian?a de 95%. Os sistemas de fixa??o utilizando miniplacas quadradas (G2) e retangulares (G3) obtiveram resultados similares, sem diferen?as estatisticamente significativas em rela??o ? carga m?xima e ? carga no deslocamento de 5 mm, quando comparada ? configura??o padr?o (G1), nas fraturas sinfis?rias da mand?bula. Nas fraturas parassinfis?rias, o m?todo de fixa??o utilizando miniplacas quadradas (G5) obteve resultados sem diferen?as estatisticamente significativas no que se refere ? carga m?xima e ? carga no deslocamento de 5 mm, quando comparadas ? configura??o padr?o (G4). O m?todo de fixa??o utilizando as miniplacas retangulares (G6) obteve resultados inferiores, estatisticamente significantes, quando comparado ? configura??o padr?o (G4) nas fraturas parassinfis?rias. O comportamento mec?nico dos m?todos de fixa??o estudados foi similar, exceto nas fraturas parassinfis?rias, quando se utilizaram as miniplacas com a configura??o retangular. Os m?todos de fixa??o utilizados apresentaram melhores resultados, com signific?ncia, nas fraturas sinfis?rias

O entendimento sobre os processos de fraturas em materiais à de grande importÃncia para a fÃsica e indÃstrias da construÃÃo civil. AtravÃs dos processos de fraturas podemos compreender melhor as propriedades elÃsticas dos materiais, como seu mÃdulo de Young macroscÃpico, tensÃo de ruptura e mÃdulo de rigidez. Podemos definir os processos de fraturas como sendo aqueles que dividem um sistema em duas ou mais partes, destruindo a conexÃo global dos elementos que o constituem. Nesse contexto, no primeiro capÃtulo à feito uma descriÃÃo matemÃtica das equaÃÃes da mecÃnica do contÃnuo, no segundo capÃtulo aborda-se o modelo de elementos discretos (DEM) que à um mÃtodo numÃrico capaz de descrever o comportamento mecÃnico de materiais granulados. No terceiro capÃtulo, construÃmos o modelo computacional para estudar, as propriedades mecÃnicas de 3 tipos de amostras, cristalina, amorfa e multifÃsica. O modelo computacional utilizado se mostrou bastante interessante e apresentou resultados que podemos considerar como sendo satisfatÃrios. / O entendimento sobre os processos de fraturas em materiais à de grande importÃncia para a fÃsica e indÃstrias da construÃÃo civil. AtravÃs dos processos de fraturas podemos compreender melhor as propriedades elÃsticas dos materiais, como seu mÃdulo de Young macroscÃpico, tensÃo de ruptura e mÃdulo de rigidez. Podemos definir os processos de fraturas como sendo aqueles que dividem um sistema em duas ou mais partes, destruindo a conexÃo global dos elementos que o constituem. Nesse contexto, no primeiro capÃtulo à feito uma descriÃÃo matemÃtica das equaÃÃes da mecÃnica do contÃnuo, no segundo capÃtulo aborda-se o modelo de elementos discretos (DEM) que à um mÃtodo numÃrico capaz de descrever o comportamento mecÃnico de materiais granulados. No terceiro capÃtulo, construÃmos o modelo computacional para estudar, as propriedades mecÃnicas de 3 tipos de amostras, cristalina, amorfa e multifÃsica. O modelo computacional utilizado se mostrou bastante interessante e apresentou resultados que podemos considerar como sendo satisfatÃrios. / The understanding about the fractures processes in materials has a big importance for physics and civil construction industries. Through the fractures processes, we can better understand the materialsâ elastics properties as its macroscopic Young module, rupture tension and rigidity module. We can define the fractures processes as those which divide a system into two or more parts, destroying the global connection of the elements that constitute it. In this context, in the first chapter, we can find a mathematical description of continuum mechanics equations. The second chapter discusses the model of Discrete Element(DEM), which is a numerical method capable of describing the mechanical behavior of granular materials. In the third chapter, we built the computational model for studying the mechanicals properties of three types of samples, crystalline, amorphous and multiphase. The computational model showed itself quite interesting and presented results which we can consider satisfactory. / The understanding about the fractures processes in materials has a big importance for physics and civil construction industries. Through the fractures processes, we can better understand the materialsâ elastics properties as its macroscopic Young module, rupture tension and rigidity module. We can define the fractures processes as those which divide a system into two or more parts, destroying the global connection of the elements that constitute it. In this context, in the first chapter, we can find a mathematical description of continuum mechanics equations. The second chapter discusses the model of Discrete Element(DEM), which is a numerical method capable of describing the mechanical behavior of granular materials. In the third chapter, we built the computational model for studying the mechanicals properties of three types of samples, crystalline, amorphous and multiphase. The computational model showed itself quite interesting and presented results which we can consider satisfactory.

Chan Cheung Shing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 88-90). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgements --- p.iv / Table of Contents --- p.v / List of Figures --- p.viii / List of Tables --- p.xii / Abbreviations and Notations --- p.xiii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background and Objective --- p.1 / Chapter 1.2 --- Contribution --- p.4 / Chapter 1.3 --- Thesis Outline --- p.5 / Chapter Chapter 2 --- System Architecture --- p.6 / Chapter 2.1 --- Conceptual Design --- p.6 / Chapter 2.2 --- Sensing Device and Fall-Detection Algorithm --- p.7 / Chapter 2.3 --- Mechanical Part --- p.10 / Chapter Chapter 3 --- Mechanical Design --- p.11 / Chapter 3.1 --- Similar Products --- p.11 / Chapter 3.1.1 --- Airbag Restraining Systems in Automobiles --- p.11 / Chapter 3.1.2 --- Airbag Jackets for Motorcycle and House Riders --- p.12 / Chapter 3.2 --- Mechanism adopted --- p.12 / Chapter 3.2.1 --- Time Requirement of Inflator --- p.12 / Chapter 3.2.2 --- Mechanism and Design --- p.13 / Chapter 3.2.3 --- Actuator --- p.14 / Chapter 3.2.4 --- Punch --- p.15 / Chapter 3.2.5 --- Airbags --- p.18 / Chapter 3.2.6 --- Other Mechanisms Tried --- p.19 / Chapter 3.3 --- Prototype --- p.21 / Chapter 3.3.1 --- Implementation --- p.21 / Chapter 3.3.2 --- Demonstration --- p.23 / Chapter Chapter 4 --- Inflation Estimation --- p.25 / Chapter 4.1 --- Theory and Model --- p.25 / Chapter 4.2 --- Validation of Model --- p.28 / Chapter 4.2.1 --- Testing Equipment --- p.28 / Chapter 4.2.2 --- Preprocessing of Pressure Sensor Outputs --- p.28 / Chapter 4.2.3 --- Validation for Basic Equations --- p.29 / Chapter 4.2.4 --- Adjustment of Discharge Coefficients --- p.36 / Chapter 4.2.5 --- Validation for Discharging to a Fixed Volume --- p.40 / Chapter 4.2.6 --- Estimation of the Size of Airbag's Leakage Hole --- p.45 / Chapter 4.2.7 --- Validation for Discharging to an Airbag --- p.47 / Chapter 4.2.8 --- Time Delay due to Addition of a Pipe --- p.52 / Chapter 4.3 --- Summary of Experiments --- p.53 / Chapter 4.4 --- Limitation of Model --- p.54 / Chapter 4.5 --- Prediction of Inflation Time and Airbag Pressure --- p.55 / Chapter 4.5.1 --- Effects of Orifice Size and Vent Size on Airbag Pressure and Volume --- p.55 / Chapter Chapter 5 --- Force Attenuation Estimation --- p.58 / Chapter 5.1 --- Theory and Model --- p.58 / Chapter 5.1.1 --- Kelvin-Voigt Model --- p.59 / Chapter 5.1.2 --- Standard Linear Solid Support Model --- p.59 / Chapter 5.2 --- Simple Testing for Validation --- p.61 / Chapter 5.3 --- Summary of Experiment --- p.64 / Chapter 5.4 --- Estimation --- p.64 / Chapter 5.4.1 --- Force Attenuation Ability of Prototype --- p.64 / Chapter 5.4.2 --- Minimum Airbag Volume and Pressure Required to Reduce the Force --- p.65 / Chapter Chapter 6 --- Future Work --- p.66 / Chapter 6.1 --- Impact Test for Airbag System --- p.66 / Chapter 6.2 --- The Effective Mass of the Target User --- p.67 / Chapter 6.3 --- The Motion Data Collection --- p.68 / Chapter 6.4 --- Modification in the Inflator --- p.69 / Chapter Chapter 7 --- Conclusion --- p.70 / Appendix A Review of Basic Thermodynamics and Fluid Dynamics --- p.72 / Chapter A.1 --- Thermodynamics --- p.72 / Chapter A.2 --- Fluid Mechanics: Incompressible and Compressible Flow --- p.75 / Appendix B Derivation of Equations --- p.77 / Chapter B.1 --- Mass Flow Rate Equations --- p.77 / Chapter B.2 --- Relationship between Rate of Changes of Airbag Pressure and Volume --- p.80 / Chapter B.3 --- Pressure Change of Compressed Gas Cylinder --- p.82 / Chapter B.4 --- Dominating Factors in the Mass Flow Rate Equation --- p.83 / Appendix C Dimensions of Inflator --- p.85 / Appendix D Experimental Data --- p.86

L'intérêt porté aux milieux fracturés s'est développé dans le cadre de l'exploitation des nappes phréatiques et pétrolifères et la recherche de sites de stockage souterrains pour les déchets nucléaires de longue durée de vie. Les fractures peuvent en effet offrir des voies préférentielles d'écoulement beaucoup plus perméables que le milieu non fracturé environnant (matrice). Les fractures sont caractérisées par des distributions de longueurs et de perméabilités très larges. Lorsque elles sont interconnectées, elles forment des réseaux complexes de perméabilité variable dans lesquels les flux sont très chenalisés. <br />Le but de ce travail de thèse a été de rechercher les modèles de réseaux cohérents avec les observations locales (distributions de longueurs et d'ouvertures) et globales (à l'échelle du réseau). Ce travail s'inscrit dans le cadre d'une approche pluridisciplinaire destinée à utiliser des données obtenues à des échelles différentes (par exemple essais de puits et données de carottage). Des modèles de réseaux bidimensionnels prenant en compte les larges distributions de longueurs et d'ouvertures ont été étudiés numériquement et théoriquement. Les résultats montrent une grande diversité de structures d'écoulement allant de la fracture unique concentrant l'intégralité du flux au modèle homogène. Le type de structure d'écoulement dépend non seulement de la densité et des distributions de longueurs et de perméabilité de fractures mais aussi de l'échelle d'observation. Dans la plupart des modèles, une échelle de transition marque le passage de structures complexes extrêmement chenalisées à des milieux dans lesquels le flux se répartit dans différentes structures indépendantes. L'évolution des structures d'écoulement s'accompagne d'une dépendance d'échelle des propriétés hydrauliques telles que la perméabilité. La perméabilité croît jusqu'à la longueur de transition avant de se stabiliser aux échelles supérieures. Cette démarche de modélisation, fondée sur des observations effectuées à des échelles locales (caractéristique de la fracturation) et validée à des échelles globales (échelles du réservoir), fournit une large gamme de modèles d'écoulement admissibles et théoriquement spécifiables à partir de données de terrain. La modélisation a été étendue à la détermination de la connectivité de réseaux d'ellipses tridimensionnels.<br />Les modèles d'écoulement les plus pertinents mis au point en régime permanent ont été étudiés en régime transitoire. Les évolutions spatiales et temporelles du rabattement dépendent des propriétés topologiques et métriques du réseau de fractures. Une analyse en fonction de la distance des essais de puits effectués sur le site de Ploemeur (Morbihan) a permis d'obtenir des résultats similaires sur un site naturel. Cependant aucune correspondance totale n'a pu être dégagée, peut être à cause de la nature éventuellement tridimensionnelle du réseau naturel. Au-delà de la prédiction des tendances moyennes, les modèles étudiés sont destinés à fournir une évaluation de la précision de la prédiction en fonction de la quantité de données disponibles. Du point de vue décisionnel, il s'agit de pouvoir estimer le risque associé à la nature incomplète des données de terrain.

Various models featuring horizontal wells with multiple induced fractures have been proposed to characterize flow behavior over time in tight gas and shale gas systems. Currently, there is little consensus regarding the effects of non-ideal fracture geometries and coupled primary-secondary fracture interactions on reservoir performance in these unconventional gas reservoirs. This thesis provides a grid construction tool to generate high-resolution unstructured meshes using Voronoi grids, which provides the flexibility required to accurately represent complex geologic domains and fractures in three dimensions. Using these Voronoi grids, the interaction between propped hydraulic fractures and secondary "stress-release" fractures were evaluated. Additionally, various primary fracture configurations were examined, where the fractures may be non-planar or non-orthogonal. For this study, a numerical model was developed to assess the potential performance of tight gas and shale gas reservoirs. These simulations utilized up to a half-million grid-blocks and consider a period of up to 3,000 years in some cases. The aim is to provide very high-definition reference numerical solutions that will exhibit virtually all flow regimes we can expect in these unconventional gas reservoirs. The simulation results are analyzed to identify production signatures and flow regimes using diagnostic plots, and these interpretations are confirmed using pressure maps where useful. The coupled primary-secondary fracture systems with the largest fracture surface areas are shown to give the highest production in the traditional "linear flow" regime (which occurs for very high conductivity vertical fracture cases). The non-ideal hydraulic fracture geometries are shown to yield progressively lower production as the angularity of these fractures increases. Hence, to design optimum fracture completions, we should endeavor to keep the fractures as orthogonal to the horizontal well as possible. This work expands the current understanding of flow behavior in fractured tight-gas and shale-gas systems and may be used to optimize fracture and completion design, to validate analytical models and to facilitate more accurate reserves estimation.

One indication of increasing fragility of bone is the accumulation of microscopic cracks, or microdamage, within the bone matrix. Microdamage accumulates in bone of the elderly, when changes in bone material properties and matrix architecture coupled with a decrease in bone repair mechanisms compromise bone integrity. To preserve bone mass and reduce fracture risk, therapeutics such as alendronate are prescribed which increase bone volume fraction by decreasing the rate of bone turnover. However, concerns over adverse effects of prolonged turnover suppression have been reinforced by findings of increased microdamage density with alendronate use. Microdamage formation is not always pathologic, but extensive accumulation of damage can be an indicator of reduced bone quality. The work in this thesis explores the hypothesis that microdamage in bone of lower quality will form more easily and progress more extensively than in bone of higher quality. Microdamage initiation stresses and strains were obtained for trabecular bone from older females, older males, and younger females to determine whether thresholds for damage initiation were lower in older females. Results suggest that the stress threshold for damage initiation in older females may indeed be lower compared with younger females, and that normalized strain thresholds for severe damage formation in older males may be decreased compared with older females. Damage propagation was evaluated as a function of age and sex to determine whether damage in older women progressed more extensively than in younger women or men. Results suggest that bone from older individuals had decreased resistance to crack propagation evidenced by an increased number of severely damaged trabeculae which expanded in area under cyclic loading; however no sex differences were uncovered. Finally, the stress/strain thresholds for damage initiation were investigated in alendronate-treated bone, and results indicate that a decreased stress threshold was needed to initiate damage formation of a linear and severe morphology after one year of treatment. After three years of treatment, however, micromechanical properties recovered, perhaps due to increased matrix mineralization which increased tissue level stiffness.