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The deep mining and civil engineering industry need to perform rock stability analyses during excavation projects. The stability is mainly controlled by the shear strength of the rock fractures, which are the weakest point of the rock mass. In turn, the shear strength is governed by the mechanical properties of the fractures. It is both time and cost demanding to determine the properties of the rock fractures in laboratory. Also, the interpretation of the results requires a deep understanding of the normal and shear behaviour of rock fractures. This study aims to investigate if it is possible to determine the peak shear strength of rock fractures by merely estimating fracture parameters during field mapping and core logging. SKB supplied test results on drilled bore cores from site investigations in Forsmark and Laxemar for deep nuclear waste deposits. SKB generated data of high quality and in large quantity, which made it very valuable for the purpose of the study. The study begins with a literature review and an interaction matrix, clarifying the relationships between mechanical properties and affecting parameters of rock fractures. The predicted relationships of the parameters are then tested in an analysis based on the compiled data from SKB. The results show that the peak friction angle, the residual friction angle and the dilation angle are possible to approximate for open granite fractures in deep mining projects. Further on, the study proposes that the joint matching coefficient is included in the field mapping and core logging since it has a strong influence on the mechanical behaviour of the fracture, notably the normal and shear stiffness. Finally, the study questions estimations of JRC on small samples.

Silicon photonics is emerging as a potential field to achieve optical interconnects towards the realization of ultra high bandwidth. The indirect band-gap property of silicon still remains as a big challenge to incorporate silicon photonic active device, for example, silicon-based laser. In the Laboratory of Semiconductor Materials at KTH, a monolithic integration platform based on nano-epitaxial lateral overgrowth (nano-ELOG) technique has been proposed to integrate III-V semiconductor materials with silicon for light source application. The integration process involves uneven surface morphology at different stages. The surfaces of the indium phosphide seed layer on silicon used for ELOG, the mask deposited on it (the silicon/silicon dioxide waveguide) and the ELOG indium phosphide layer grown on it prior to laser growth are often rough. In this thesis work, we have optimized chemical mechanical polishing (CMP) technique in order to achieve an even surface. The same procedure is also necessary to reach the optimal thickness of different layers to enable effective coupling of light from the laser source into the waveguide. CMP of indium phosphide to obtain an average surface roughness of < 1 nm has been optimized by a two-step polishing using different slurries; it results in a step height of ca 3 nm. Similarly the surface of silicon/silicon dioxide “waveguide” has also been optimized with the roughness of ~ 0.5 nm. In the latter case, a step height of 40 nm is retained and this increase with respect to InP is identified to be mainly due to limitations of the polishing machine which is different from that used for indium phosphide. The reduction in step heights with polishing time is analyzed and compared with an existing theoretical model. Our results are in good qualitative agreement with the model. The optimized surface morphology obtained in this work was tested for its suitability for integration. For this evaluation, InP was grown by ELOG in a hydride vapour phase epitaxy reactor with and without CMP of the involved surfaces. The surface after CMP yields layers of better surface morphology with fewer defects as revealed by atomic force microscopy, surface profilometer and cathodoluminescence analysis. The results indicate that the CMP process is useful for monolithic integration for silicon photonics.

Drop impacts are present in our everyday lives, from showering and washing the dishes to inkjet printing and many industrial processes, such as spray coatings and spray cooling. In many of these applications it may be undesirable to have air entrained within the drop when it impacts a surface. As a drop approaches a surface, the gas beneath the drop is unable to fully escape resulting in a rising pressure which becomes sufficient to form a dimple in the bottom center of the drop. Therefore, when the drop makes contact with the surface, it is around the perimeter of this dimple, thus entrapping a disc of air which contracts into a minute bubble. In this dissertation, we study the very early time dynamics of the formation of the central air disc under a variety of circumstances using ultra-high-speed interferometry at rates up to 5 million frames per second. We show the effects of the liquid viscosity for viscosities spanning 7 orders of magnitude, for impacts of drops onto solid surfaces or a film of the same liquid. We find that the size of the air disc is weakly dependent on the drop viscosity to the -1/9 power. We also explore the extended gliding of the drop on a less than 160 nm thick film of air. For impacts onto a solid surface, this gliding layer is rupture in multiple random locations and each localized contact wets the surface at extreme rates compared with the expected viscous-capillary velocity. For impacts onto liquid films, the localized contacts are rarely observed and the gliding layer ruptures at a uniform location. The central bubble contracts much faster than expected in this case as well. Furthermore, we study the effects of reducing the ambient air pressure discovering a compressible and rarified-gas regime wherein the drop makes a double contact with the surface. Lastly, we study the effects of nano-scale surface roughness on the central bubble and the formation of thick bands of microbubbles around the periphery of the air disc.

Indiana University-Purdue University Indianapolis (IUPUI) / Erosive tooth wear (ETW) is an emerging dental condition manifested clinically as tooth surface loss, eventually impairing the teeth’s structural integrity, function, and esthetics. Both research and practice are in need of a quantitative, non-destructive method to monitor ETW. Cross-polarization optical coherence tomography (CP-OCT), an advanced imaging tool, shows great potential to fulfill this need, but its feasibility and shortcomings remain unclear. In this dissertation, I explored the capability of CP-OCT to monitor ETW in three in vitro studies, one per chapter. Chapter 2 investigated the effects of enamel surface roughness and dental erosion severity on CP-OCT dental surface loss measurements. Chapter 3 tested the effects of enamel surface roughness and dental erosion on CP-OCT enamel thickness measurements at different simulated wear levels. Chapter 4 explored the ability of CP-OCT to quantify the thickness of natural and wornout enamel surfaces and to estimate longitudinally the wear depths resulting from simulated wear. I concluded: (1) enamel surface roughness did not affect CP-OCT measurements of enamel surface loss, however, the estimated error limited the appropriate assessment of the initial stages of dental erosion surface loss using CP-OCT; (2) enamel surface roughness and dental erosion did not affect CP-OCT enamel thickness measurements, and the CP-OCT differentiated the simulated enamel wear levels; and (3) CP-OCT quantified thickness of natural enamel before, during, and after the tooth wear simulation and allowed wear depth estimation following the simulated wear. / 2021-07-03

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19184号 / 工博第4061号 / 新制||工||1626(附属図書館) / 32176 / 京都大学大学院工学研究科マイクロエンジニアリング専攻 / (主査)教授 田畑 修, 教授 琵琶 志朗, 准教授 土屋 智由, 教授 松原 厚 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19687号 / 工博第4142号 / 新制||工||1639(附属図書館) / 32723 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 斧 髙一, 教授 稲室 隆二, 教授 青木 一生 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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