L'évaluation de la stabilité des falaises est complexe, du fait de l'incertitude des mécanismes de rupture et de la méconnaissance de l'état de fracturation interne du massif. Les méthodes géophysiques permettent d'obtenir de l'information sur la structure interne du massif. Le radar géologique a montré son efficacité pour détecter et caractériser les fractures. Plusieurs profils radar (réflexion, transmission, CMP) sont testés sur deux falaises verticales calcaires proches de Grenoble. La combinaison de profils verticaux et horizontaux permet de mieux contraindre la géométrie 3D du réseau de fractures. Les analyses de vitesses radar, déduites des acquisitions CMP, permettent de caractériser directement les larges fractures ouverture en profondeur. La tomographie radar fournit une image 2D de l'intérieur du massif, mais avec une trop faible résolution. Dans une gamme de fréquences donnée, la détection de fractures par le radar va dépendre de l'ouverture et du remplissage, qui contrôlent le coefficient de réflexion. Une stratégie de caractérisation des fractures est proposée en utilisant la sensibilité fréquentielle de la réflectivité. L'inversion des coefficients de réflexion radar, basée sur un algorithme de voisinage, permet de retrouver les paramètres caractéristiques des fractures modélisées. La méthode du rapport spectral entre un signal réfléchi (mesuré) et un signal de référence (connu), permet de calculer facilement le coefficient de réflexion. Une étude numérique 2D (FDTD) est menée pour le choix du signal de référence. L'inversion des coefficients de réflexion radar synthétiques est testée pour une configuration de fracture ouverte rencontrée sur le terrain.

La cryopréservation par vitrification est une technique qui devrait permettre de rallonger considérablement les durées de conservation des greffons en abaissant leur température de stockage jusqu'à – 196°C. Elle nécessite l'utilisation de solutions cryoprotectrices (contenant des antigels biocompatibles) pour empêcher la cristallisation de glace dans les tissus, ainsi que des vitesses de variation de la température relativement rapides. La calorimétrie différentielle à balayage permet de déterminer les vitesses requises pour la vitrification des solutions cryoprotectrices. L'exemple de l'éthylène glycol est présenté, complétant les informations connues sur ce cryoprotecteur dans la plage des concentrations concernant la vitrification. Au niveau de la procédure de vitrification, la méthode du recuit a permis d'éviter l'apparition de fractures dans des volumes importants de solution cryoprotectrice. Le cas particulier de la solution VM3 (21st Century Medicine) est détaillé. Il permet de montrer que la stabilité de l'état amorphe ainsi que la quantité de glace cristallisée au réchauffement sont influencées par la température et la durée du recuit. Une analyse sur l'influence du type et de la forme du container porte-échantillon par rapport à la qualité du verre fabriqué a été commencée en parallèle, mais les limites du dispositif cryogénique utilisé nous ont poussé à développer un nouveau cryostat automatisé, permettant de faire des études systématiques dans des conditions reproductibles. Ce cryostat, entièrement conçu et construit au CRTBT, représente le prototype de ce que nous souhaitons proposer à des médecins pour les aider dans leur étude clinique de la cryopreservation des systèmes biologiques. Sa précision de mesure et sa facilité d'utilisation nous a pour le moment permis de mettre en évidence différents événements ayant lieu pendant la vitrification et le réchauffement de nos échantillons.

<p>Saab Microwave Systems, SMW is a supplier of radar systems. The circuit boards that are operating in their radars have components which solder joints contains lead. However, the EU directive RoHs and WEEE are causing SMW to prepare for a transition to lead free solder joints. The objective of this thesis is to gain deeper knowledge of lead free solder joints.</p><p>Brittle fractures in solder joints is a type of failure that might increase in a transition to lead free solder joints. The brittle fractures are induced by the creation of the intermetallic phases which are formed during soldering. The amount and composition of the intermetallics affects the mechanical strength of the joint. An intermetallic layer is thickened during heat exposure as during soldering, thermal aging and rework.</p><p>The focus of this thesis was to investigate how rework affect the brittleness of the lead free solder joint and thereby how the intermetallic layers change depending on chemical composition, design and reflow cycles. Two types of components and two types of solder materials (SnPb and SAC305) were studied.</p><p>To study the mechanical properties of the joint a shear testing device was used. This is a way of measuring the reliability of the joint when subjected to mechanical shock. The intermetallic layers were examined in a Scanning Electron Microscope and the fracture surfaces were studied in a optical microscope, a scanning electron microscope and a stereomicroscope. The heat spread over the board where examined by soldering thermocouples to the board and plotting the values of time and temperature.</p><p>The results showed that the rework process did not have any significant impact of the intermetallic growth. The adjecent and distant components were not damaged during rework. A lead free rework process can therefor be preformed successfully at SMW. The intermetallic layers formed at the interface between the a lead free solder and a nickel finish grew faster than an intermetallic layer formed between a leaded solder and a nickel finish. The presence of nickel could therefore have a more negative effect on the intermetallic growth rate for the lead free material compared to the leaded.</p>

Le comportement géotechnique des massifs rocheux est principalement régi par leurs discontinuités. Celles-ci ont pour cause les déviateurs de contrainte et de déformation appliqués au massif tout au long de son histoire géologique. On en conclut que les caractéristiques mécaniques et hydrauliques actuelles d'un massif dépendent à la fois de ses particularités structurales acquises et éventuellement de contraintes s'exerçant de nos jours, notamment par suite du mouvement des plaques lithosphériques. L'appréciation de la qualité d'un site doit s'efforcer de combiner l'analyse structurale, les mesures in situ et, si possible, les données acquises par la sismologie. Une telle démarche permet de généraliser les résultats de reconnaissances par nature ponctuelles et de mieux comprendre certaines anisotropies mécaniques et hydrauliques. Des études de sites de fondation de barrages, en terrains cristallins et cristallophylliens, effectuées en Arabie Séoudite et dans les Pyrénées-Orientales illustrent la démarche méthodologique qui vient d'être proposée.

Displaced femoral neck fractures comprise more than a third of all hip fractures. There is controversy as to the optimal treatment. Despite attempts to improve the methods for internal fixation, complication rates have been almost unchanged: 20-40% non-union and late segmental collapse in another 10-20%. Internal fixation has been the preferred treatment in Scandinavia, whereas primary hemi- or total arthroplasty have been more prevalent in the rest of Europe and North America. In this study, patients 75 years or older, including those with mental impairment, were randomized to either internal fixation or cemented primary total hip arthroplasty (THA). A total of 146 hips in 143 patients were followed for two years. After one year 23% had died, and after two years 29%. Mortality was about the same in both groups. The accumulated mortality was pronounced among the mentally impaired patients. In the internal fixation group, 44% underwent further surgery. In the THA group, 18% dislocated. The dislocation rate was higher for the mentally impaired patients. The Harris hip scores were higher in the THA group, whereas pain was more common in the internal fixation group. The first 50 patients in each treatment group were studied concerning heterotopic ossification (HO), a well-known complication after THA. The incidence of HO in the THA group was similar to what is found after THA due to osteoarthritis. However, only 1/39 developed severe symptoms. A subgroup of 100 patients was included in a study concerning nutritional status and functional capacity using the Modified Norton scale, Katz index of ADL and a questionnaire measuring instrumental activities of daily living. The THA group fared better concerning weight change over time, locomotion and pain. The nutritional intervention did not show any measurable effects. All patients were followed until two years postoperatively and all fracturerelated hospital costs, including reoperations, were calculated. We found no difference in total costs between the treatment groups. Costs to the municipality were calculated comparing the baseline cost before surgery with the average cost per month during the first postoperative year. No difference was found between the treatment groups. On the basis of our results, we recommend arthroplasty for patients in this age group with normal mental function and high functional demands.

The intent of this thesis is to contribute to the understanding of the origin of fractures in rock. The man-made fracturing from engineering activities in crystalline rock as well as the fracturing induced by the natural process of meteorite impacts is studied by means of various characterization methods. In contrast to engineering induced rock fracturing, where the goal usually is to minimize rock damage, meteorite impacts cause abundant fracturing in the surrounding bedrock. In a rock mass the interactions of fractures on the microscopic scale (mm-cm scale) influence fractures on the mesoscopic scale (dm-m scale) as well as the interaction of the mesocopic fractures influencing fractures on the macroscopic scale (m-km scale). Thus, among several methods used on different scales, two characterization tools have been developed further. This investigation ranges from the investigation of micro-fracturing in ultra-brittle rock on laboratory scale to the remote sensing of fractures in large scale structures, such as meteorite impacts. On the microscopic scale, the role of fractures pre-existing to the laboratory testing is observed to affect the development of new fractures. On the mesoscopic scale, the evaluation of the geometric information from 3D-laser scanning has been further developed for the characterisation of fractures from tunnelling and to evaluate the efficiency of the tunnel blasting technique in crystalline rock. By combining information on: i) the overbreak and underbreak; ii) the orientation and visibility of blasting drillholes and; iii) the natural and blasting fractures in three dimensions; a analysis of the rock mass can be made. This analysis of the rock mass is much deeper than usually obtained in rock engineering for site characterization in relation to the blasting technique can be obtained based on the new data acquisition. Finally, the estimation of fracturing in and around two meteorite impact structures has been used to reach a deeper understanding of the relation between fracture, their water content and the electric properties of the rock mass. A correlation between electric resistivity and fracture frequency in highly fractured crystalline rock has been developed and applied to potential impact crater structures. The results presented in this thesis enables more accurate modelling of rock fractures, both supporting rock engineering design and interpretation of meteorite impact phenomena. / QC 20100709

The presence of fractures, joints and karst features within rock strongly influence the hydraulic and mechanical behavior of a rock mass, and there is a strong desire to characterize these features in a noninvasive manner, such as by using ground penetrating radar (GPR). These features can alter the incident waveform and polarization of the GPR signal depending on the aperture, fill and orientation of the features. The GPR methods developed here focus on changes in waveform, polarization or texture that can improve the detection and discrimination of these features within rock bodies. These new methods are utilized to better understand the interaction of an invasive shrub, Juniperus ashei, with subsurface flow conduits at an ecohydrologic experimentation plot situated on the limestone of the Edwards Aquifer, central Texas. First, a coherency algorithm is developed for polarimetric GPR that uses the largest eigenvalue of a scattering matrix in the calculation of coherence. This coherency is sensitive to waveshape and unbiased by the polarization of the GPR antennas, and it shows improvement over scalar coherency in detection of possible conduits in the plot data. Second, a method is described for full-waveform inversion of transmission data to quantitatively determine fracture aperture and electromagnetic properties of the fill, based on a thin-layer model. This inversion method is validated on synthetic data, and the results from field data at the experimentation plot show consistency with the reflection data. Finally, growing hierarchical self-organizing maps (GHSOM) are applied to the GPR data to discover new patterns indicative of subsurface features, without representative examples. The GHSOMs are able to distinguish patterns indicating soil filled cavities within the limestone. Using these methods, locations of soil filled cavities and the dominant flow conduits were indentified. This information helps to reconcile previous hydrologic experiments conducted at the site. Additionally, the GPR and hydrologic experiments suggests that Juniperus ashei significantly impacts infiltration by redirecting flow towards its roots occupying conduits and soil bodies within the rock. This research demonstrates that GPR provides a noninvasive tool that can improve future subsurface experimentation.

Diss. (sammanfattning) Umeå : Umeå universitet, 2009. / Härtill 4 uppsatser. Även tryckt utgåva.

This study provides new insights on the mechanisms that controlled the development of solution-enhanced fractures and suprastratal deformation associated with the Mississippian Madison Sequence IV evaporite paleokarst complex. Based on detailed field mapping utilizing LiDAR, GPS, and field observations, we document a paleostructural high (oriented 145º) associated with the Ancestral Rockies uplift within the study area. One hundred twenty-one sediment-filled, solution-enhanced fractures within the Seq. IV cave roof were mapped and characterized by their dominant fill type (Amsden or Madison) and vertical extent. Spatial analysis reveals minimum spacing of these features occurs in areas uplifted during the Late Paleozoic suggesting a link between paleostructural position and solution feature spacing. Shape analysis of these solution features also supports structural position during the Late Paleozoic acted as a dominant control on fracture morphology: (1) downward tapering and fully penetrative features concentrate in areas that experienced uplift; (2) upward tapering concentrate in areas that were undeformed. Mapping of Seq. IV cave roof strata demonstrates vertical collapse variability exceeds 22 m and fault intensity increases in areas of increased collapse. These findings have significant implications for prediction and characterization of solution-enhanced fractures and suprastratal deformation within evaporite paleokarst systems. / text

An appreciation of the extent of syndepositional fracturing, faulting, and cementation of carbonate platform margins is essential to understanding the role of early diagenesis and compaction in margin deformation. This study uses integrated lidar and outcrop data along the Capitan Reef from an area encompassing the mouths of both Rattlesnake and Walnut Canyons. Mapping geomorphic expressions of syndepositional faults and fractures at multiple scales of observation was the main approach to delineating zones of syndepositional fractures. Ridge- groove couplets visible in exposures of the Capitan Reef throughout the Guadalupe Mountains were targeted because the ability to identify these as signs of syndepositional fracture development would have implications for the entire reef complex. Results show that these ridgegroove couplets are the product of differential weathering of syndepositional as well as burial-related fractures. Recessive grooves have an average syndepositional fracture spacing of ~13 m whereas ridges have a spacing of ~33 m. vi Smaller (~5-20 m-wide) scale erosional lineaments common in the study area and mappable on airborne lidar are formed by differential erosion of planes of syndepositional faults. Maps of these fault lineaments on the lidar show that syndepositional faults extend laterally for 300 m - 2000 m and relay near the terminations of the faults at each end. Faults can be further grouped into fault systems consisting of sets of faults connected by fault relays that extend for at least the entire length (~12 km) of the study area. Although vertical displacement along faults is typically less than 11 m, syndepositional faults result in changes in structural dip domain of 1-6 degrees across an individual fault. Even smaller erosional lineaments (10 cm-1 m) are visible on the airborne lidar that form as a result of differential erosion of individual fractures. Larger fractures (> 20 cm) can be reliably mapped on the lidar, but smaller features (< 20 cm) cannot be reliably mapped with currently available data and can only be captured using field studies. Fracture fill types are heterogeneous along strike as shown by comparisons of field study locations. Siliciclastic-dominated fills are likely sourced from overlying siliciclastic units of the shelf, which, in this area, were from the Ocotillo Siltstone. These silt-filled fractures are broadly distributed, indicating preferential development and infill of syndepositional fractures during the deposition of the Ocotillo Siltstone in the G27/28 high-frequency sequences. Development of early fractures is also shown to have been influenced by mechanical stratigraphy with changes in fracture spacing between massive to thick-bedded shelf-margin (~17 m fracture spacing) and outer-shelf facies tracts versus thin-bedded outer-shelf and shelf-crest (~28 m fracture spacing). Ultimately, this study demonstrated that the Capitan shelf margin was ubiquitously overprinted by syndepositional fracturing and faulting and that this nearsurface structural modification influenced early diagenetic patterns and internal vii sedimentation throughout the reef margin. Before this study, the extent and nature of syndepositional fracture/fault development within the margin were largely unquantified. Here, by integrating field observations and surface weathering reflections of these fractures as observed in the lidar, we can demonstrate a widespread impact of early fracturing more akin to analogous early-lithified margins such as the Devonian of the Canning Basin of Australia. / text