This thesis presents an analytical treatment of surface waves inside a dielectric slab loaded with a conductive and spatially dispersive semiconductor-like substrate. The work is primarily focused on the modelling of the substrate and getting the field solutions out from the Helmholtz equation. Appropriate boundary conditions have been used in order to get a unique dispersion relation. The surface wave modes are then extracted from the relation by using a root-searching algorithm, which in this work is the MATLAB Genetic Algorithm toolbox. Many different substrate configurations have been considered, starting from the very basic isotropic case to the most complex spatial dispersion case. In between, anisotropicity has also been added to the substrate by turning the static magnetic field on. The permittivity tensors are derived from the fluid transport equations and through the course of the thesis, extra terms such as plasma oscillations, damping, cyclotron resonance, and density perturbations are added. Many assumptions, approximations, and limitations of this analytical treatment have also been addressed. Simulations results have been shown to see the effects of these various terms. The substrates analyzed in the chapters are only a theoritical approximation of an actual substrate. The main idea behind this study is to get a feel for how the transport equations can be utilized to obtain properties that might be on a macroscopic scale. The physical significance of this expose has also been discussed in the last chapter. Issues such as scalability to space plasmas and future ramifications are also included. The study done thus far will be useful in investigating such plasma mediums.

abstract: The depth richness of a scene translates into a spatially variable defocus blur in the acquired image. Blurring can mislead computational image understanding; therefore, blur detection can be used for selective image enhancement of blurred regions and the application of image understanding algorithms to sharp regions. This work focuses on blur detection and its application to image enhancement. This work proposes a spatially-varying defocus blur detection based on the quotient of spectral bands; additionally, to avoid the use of computationally intensive algorithms for the segmentation of foreground and background regions, a global threshold defined using weak textured regions on the input image is proposed. Quantitative results expressed in the precision-recall space as well as qualitative results overperform current state-of-the-art algorithms while keeping the computational requirements at competitive levels. Imperfections in the curvature of lenses can lead to image radial distortion (IRD). Computer vision applications can be drastically affected by IRD. This work proposes a novel robust radial distortion correction algorithm based on alternate optimization using two cost functions tailored for the estimation of the center of distortion and radial distortion coefficients. Qualitative and quantitative results show the competitiveness of the proposed algorithm. Blur is one of the causes of visual discomfort in stereopsis. Sharpening applying traditional algorithms can produce an interdifference which causes eyestrain and visual fatigue for the viewer. A sharpness enhancement method for stereo images that incorporates binocular vision cues and depth information is presented. Perceptual evaluation and quantitative results based on the metric of interdifference deviation are reported; results of the proposed algorithm are competitive with state-of-the-art stereo algorithms. Digital images and videos are produced every day in astonishing amounts. Consequently, the market-driven demand for higher quality content is constantly increasing which leads to the need of image quality assessment (IQA) methods. A training-free, no-reference image sharpness assessment method based on the singular value decomposition of perceptually-weighted normalized-gradients of relevant pixels in the input image is proposed. Results over six subject-rated publicly available databases show competitive performance when compared with state-of-the-art algorithms. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第20032号 / 情博第627号 / 新制||情||109(附属図書館) / 33128 / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 原田 博司, 教授 守倉 正博, 教授 梅野 健 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21756号 / 工博第4573号 / 新制||工||1713(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 蓮尾 昌裕, 教授 木村 健二, 教授 江利口 浩二 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

In this thesis we study photonic computation within the framework of reservoir computing. Inspired by the insight that the human brain processes information by generating patterns of transient neuronal activity excited by input sensory signals, reservoir computing exploits the transient dynamics of an analogue nonlinear dynamical system to solve tasks that are hard to solve by algorithmic approaches. Harnessing the massive parallelism offered by optics, we consider a generic class of nonlinear dynamical systems which are suitable for reservoir computing and which we label photonic computing liquids. These are spatially extended systems which exhibit dispersive or diffractive signal coupling and nonlinear signal distortion. We demonstrate that a wide range of optical systems meet these requirements and allow for elegant and performant imple- mentations of optical reservoirs. These advances address the limitations of current photonic reservoirs in terms of scalability, ease of implementation and the transition towards truly all-optical computing systems.We start with an abstract presentation of a photonic computing liquid and an in-depth analysis of what makes these kinds of systems function as potent reservoir computers. We then present an experimental study of two photonic reservoir computers, the first based on a diffractive free-space cavity, the second based on a fiber-loop cavity. These systems allow us to validate the promising concept of photonic computing liquids, to investigate the effects of symme- tries in the neural interconnectivity and to demonstrate the effectiveness of weak and distributed optical nonlinearities. We also investigate the ability to recover performance lost due to uncontrolled parameters variations in unstable operating environments by introducing an easily scalable way to expand a reservoir’s output layer. Finally, we show how to exploit random diffraction in a strongly dispersive optical system, including applications in optical telecom- munications. In the conclusion we discuss future perspectives and identify the characteristic of the optical systems that we consider most promising for the future of photonic reservoir computing. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

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In the 21st century the safe disposal of highly radioactive nuclear waste remains a major challenge to humanity. For the first 300 years nuclear fission products will be the main source of large amounts of the radioactivity, however, over a period of 100,000s of years most of the radiotoxicity of nuclear waste will originate from transuranium elements such as Pu, Am, and Cm. Because of the reducing conditions within a potential deep underground repository Am and Cm will exclusively – and Pu at least partially – be present in their trivalent state. For the safety case of a repository, it will be of importance to understand the mobility and retention behavior of those trivalent actinides within the host rock environment. Here, the focus is set on crystalline rock, a host rock under consideration in many countries such as Finland, Sweden, Czech Republic, and also Germany. Research in the last two decades has focused on determining the chemical speciation behavior of radionuclides on the molecular scale using primarily pure, individual mineral phases in their pulverized form. Real crystalline rock systems, on the km scale of a repository, are however much more complex, physically large and bulky, and heterogeneous. Parameters, such as heterogeneity of topography or composition, and competing surface processes have to be considered adequately in transport modelling as well as the safety assessment and thus large-scale experiments without the loss of molecular level information are needed. In this work, the focus was set on the assessment of parameters affecting chemical speciation and retention of Cm(III) and its chemical homologue Eu(III) at 5·10-7 M to 10-4 M concentrations on surfaces of crystalline rocks, relevant to potential future repositories. Correlative spectromicroscopy as a combination of spatially resolved techniques, was applied to study mineralogy, surface topography, quantitative metal ion uptake, and surface metal speciation on the same thin sections in the mm to cm scale with μm resolution. Cm(III) sorption experiments on cleaved K-feldspar crystals at pH 5.5 and 6.9 using autoradiography in conjunction with micro-focus time-resolved laser-induced fluorescence spectroscopy (μTRLFS), and vertical scanning interferometry, showed that sorption uptake and speciation is dependent on pH and surface roughness. In regions expressing a high surface roughness quantitatively more Cm(III) sorbed to the surface than in smoother regions. Further, the formed Cm(III) surface complexes are more strongly bound in regions with a high roughness, since they possess a higher number of strong sorption sites. The speciation between smooth and rough surfaces does not differ at pH 5.5. In contrast, at pH 6.9 in rougher areas, stronger species form favorably in addition to weaker surface sorption species. For comparison, Cm(III) sorption at pH 7.3 was conducted on a granodiorite crystalline rock thin section from the Grimsel Test Site, Switzerland with an inclusion of a large K-feldspar mineral grain. The spectromicroscopy approach was extended by Raman-microscopy to identify the surface mineralogy. From calibrated autoradiography of the entire thin section, it could be assessed that most sorption occurs on mica minerals rather than on feldspar. However, the K-feldspar grain was investigated in detail for a comparison of Cm(III) speciation on crystals and natural grains. On the grain, the sorption was heterogeneously distributed mainly occurring in rough surface regions. Since the overall sorption uptake was lower, the dominant species formed are bound strongly to the surface occupying strong sorption sites. Complexes were observed that were either the result of ternary complexation on the surface or incorporation. While sorption on K-feldspar crystals was higher than on the mineral grain, no ternary complexation could be observed, therefore the formation of this species is likely a result of the heterogeneous mineralogy. The formation of those complexes with carbonate is likely, whereas silicate does not seem to contribute. The exact complex structure determination will be the focus of future work. Increasing the complexity of the system, the next step was to study Cm(III) sorption at pH 8.0 on entire crystalline rock thin sections and analyzing speciation within and between different mineral gains. The focus was set on granite from Eibenstock, Germany and gneiss from Bukov, Czech Republic. On granite, sorption was highest on mica as well as feldspar and smallest on quartz as measured on the sub-mm to cm scale by quantitative autoradiography. On quartz regions, where surface roughness was higher, sorption quantities close to those on feldspar and mica could be observed. A detailed μTRLFS analysis shows highest sorption quantities on topaz, followed by feldspar, and only minor uptake was detected on quartz. Assessment of Cm(III) uptake on mica was not possible due to strong quenching of the Cm(III) luminescence through Fe as part of the mineral structure. Sorption on topaz, feldspar, and quartz occurred preferably in regions with a high surface roughness, such as surface pits, cracks, or mineral grain boundaries between the grains. Surface complexes in high roughness regions are bound more strongly than in smoother regions. A process that could either be Cm(III) ternary complexation or incorporation was exclusively observed on feldspar and quartz, likely because more sorption sites allowed for surface incorporation after which ternary complexation can occur. The experiments showed that mineralogy is the most important parameter when it comes to surface sorption, however it is closely followed by the surface roughness. On gneiss the overall mineralogy was different, which in turn affected the surface Cm(III) uptake. Combining the results from Raman microscopy and autoradiography, sorption was found almost exclusively on amphibole and mica, while little to no sorption was observed on feldspar and quartz. Due to the high Fe content of amphibole and mica, quenching hindered Cm(III) luminescence detection using μTRLFS. However, on feldspar and quartz μTRLFS allowed for uptake and speciation analysis. While no uptake was seen in smooth regions, uptake was increased in rougher regions. This highlights that in a competitive sorption environment, on low sorbing mineral phases, sorption is controlled by surface roughness. Cm(III) uptake and speciation analysis on mica using μTRLFS proved to be difficult because of luminescence quenching induced by structurally incorporated Fe in the minerals. However, to tackle this challenge, Cm(III) sorption experiments were performed on a granitic pegmatite from Olkiluoto, Finland at adjusted experimental settings, i.e., using a five times higher metal concentration than in previous experiments. Autoradiography as well as μTRLFS showed that Cm(III) sorption mainly occurred on mica, while uptake on feldspar and quartz was minor. Mica itself can be found as part of small cracks and pits, or as large grains. Inherently mica showed a high surface roughness, however Cm(III) uptake and speciation differed between the differently sized grains. On smaller grains, uptake was lower than on the larger grains, resulting in primarily stronger inner-sphere sorption species that formed. The high uptake on larger grains lead additionally to the formation of weaker inner-sphere sorption species. To compare the obtained Cm(III) results Eu(III) sorption was performed on a granite thin section. It was observed that Eu(III) uptake and speciation not only occurs heterogeneously between different minerals, but also within single grains particularly close to mineral grain boundaries. This implies that surface roughness, next to mineralogy, influences the sorption process. However, the detection of Eu(III) was hindered by surface precipitation, naturally incorporated Eu(III), and thus vague luminescence peak analysis. Spatially resolved correlative spectroscopy workflows that were further optimized in this thesis proved to be universally applicable in the range of mineral crystals to different crystalline rock thin sections and luminescent metals (Cm, Eu) and can be taken in the future as references for further studies with other luminescence metals such as Am(III) or U(VI). The derived findings show that in future assessments of the mobility of trivalent radionuclides in reactive transport modelling, parameters need to be selected carefully. Additional processes and parameters not considered before, like the surface roughness, will influence the retention of radionuclides within the geosphere. Those processes and parameters need to be quantified and implemented in the models to represent the deep repository system more reliable.

Understanding the link between environmental factors such as disturbance events, land cover, and soil productivity to spatial variation in animal distributions and vital rates is fundamental to population ecology and wildlife management. The Longleaf pine (Pinus palustris; hereafter, LLP) ecosystem is an archetypal fire-mediated ecosystem, which has seen drastic reductions in land area due to fire suppression. Current restoration utilizes prescribed fire and hardwood removal, but more research is needed to understand the influence of these restoration efforts on the wildlife that exist in that ecosystem. As such, we conducted field surveys on Camp Blanding Joint Training Center and Wildlife Management Area to understand how fire influences relative abundances of mammalian predators, occupancy and species richness of avian species, guilds and communities, and vital rates of white-tailed deer (Odocoileus viginianus) fawns. Our results indicated that mammalian predator space use, and avian species richness were influenced by fire and land cover. Mammalian predator space use was altered by fire conditions and land cover. This mechanism may support predator management strategies that utilizes commonly management techniques for the restoration and conservation of the LLP ecosystem to indirectly alter predator distributions, which has the potential to positively affect the management of important species within this ecosystem. Some mammalian mesocarnivores historically common throughout the southeastern United States were rarely detected, suggesting more research is needed to identify the cause of the potential decline in mesocarnivores in the Southeastern United States. Avian species richness at the community level was positively influenced by the heterogeneity of post fire conditions, or pyrodiversity. Avian species richness of the cavity nesting guild was negatively influenced by increasing time-since-fire. Our results suggest that managers can promote avian community diversity by reducing the size of burn units to create areas with multiple adjacent burn units, with unique fire histories and a mosaic of post-fire conditions. Lastly, fawn recruitment was greater on the higher productivity site than the low productivity site on CB. However, within sites soil productivity did not have a demonstrable effect. In fact, we observed differences between sites, but did not observe any effects of covariates on spatial variation in density or survival of fawns within sites. Although we did not explicitly test the factors influencing our parameters between sites, we hypothesize that the variation in coyote activity rates as well as soil productivity and its subsequent effects (i.e. forage availability, concealment cover, and land cover type) likely drove the differences we saw between sites. These results are relevant to local managers and provide support for unit-specific, deer management on CB. In conclusion, understanding the influence of fire in a frequently burned landscape allows us to better inform management of predators and avian communities using prescribed burns, and the differences in deer populations between areas allowed us to better in inform managers on harvest quotas so that the magnitude of the effect of harvest can better match the population vital rates of each area. / Master of Science / Understanding the link between environmental factors such as fire, land cover and soil productivity is essential for wildlife managers to maintain healthy wildlife populations. The Longleaf pine (Pinus palustris) ecosystem requires frequent fire and has seen drastic reductions in land area due to fire suppression. Current restoration utilizes prescribed fire, controlled burning of an area, and hardwood removal, logging hardwood trees such as oaks, but more research is needed to understand how this restoration influences the wildlife in the longleaf pine ecosystem. As such, we collected data collected from Camp Blanding Joint Training Center and Wildlife Management Area to understand how fire influences the relative numbers of mammalian predators, the distribution and species richness (i.e. number of unique species) of avian species, guilds and communities, and vital rates (i.e. births, survival to a certain age) of white-tailed deer fawns. Our results indicated that mammalian predator distributions, and avian species richness were influenced by fire and land cover. Mammalian predator space use was altered by fire conditions and landcover, which supports a predator management strategy that utilizes prescribed burning and hardwood removal used in restoration and conservation of the LLP ecosystem to indirectly alter predator distributions. Some mammalian mesocarnivores (i.e. foxes, skunks, weasels, etc.) historically common throughout the southeastern United States were rarely detected, suggesting more research is needed to identify the cause of the potential decline of cryptic mesocarnivores in the Southeastern United States. Avian species richness, number of unique species, at the community level was positively influenced by pyrodiversity, the number of unique burn years in an area. This supports and further extends the 'pyrodiversity begets biodiversity' hypothesis for avian species, which states that greater pyrodiversity increases the diversity of bird species in that area. Avian species richness of cavity nesting birds decreased with increasing time since fire. Our results suggest that managers can promote avian community diversity by reducing the size of burn units to create areas with multiple adjacent burn units, with unique fire histories and a mosaic of post-fire conditions. Lastly, fawn recruitment was greater on the higher productivity site than the low productivity site, however, within sites soil productivity did not seem to influence birth and recruitment. Although we did not statistically test the factors influencing our parameters between sites, we hypothesize that the variation in coyote activity rates as well as soil productivity and its subsequent effects (i.e. forage availability, concealment cover, and land cover type) likely drove the differences we saw between sites. These results are relevant to local managers and provide support for managing deer differently across both sites. In conclusion, understanding the influence of fire in a frequently burned landscape allows us to better inform management of predators and avian communities using prescribed burns, and the differences in deer populations between areas allowed us to better in inform managers on harvest quotas so that the magnitude of the effect of harvest can better match the population vital rates of each area.