The analysis of the uniformity of a spherically averaged Hubble expansion in the Local Group frame of reference by Wiltshire, Smale, Mattsson and Watkins (2013) is extended. We carry out an investigation to constrain the frame of reference from which the spherically averaged Hubble expansion is the most uniform by applying arbitrary Lorentz boosts to the data. The proposition of a systematic boost offset between the Hubble expansion in the Local Group and CMB reference frames is verified within statistical uncertainties. This evidence further supports the claim that the Local Group is closer to the frame of reference in which Hubble expansion should be considered. We subsequently carry out a statistical analysis in search of a frame of minimum expansion variation and find consistent results with the systematic boost offset analysis. However, there is a considerable degeneracy to perform boosts in the plane of the galaxy, which may be a consequence of a lack of constraints from the Zone of Avoidance where data is absent. The COMPOSITE sample of 4,534 galaxies is used primarily, with the key results repeated with the recently released Cosmicflows-2 sample of 8,162 galaxies. The treatment of Malmquist distance bias is investigated in the context of the Cosmicflows-2 and COMPOSITE samples. We find systematic differences in the inclusion of the large SFI++ subsample into these catalogues. These differences are explored and the origin of Malmquist distance bias reviewed. We find the Cosmicflows-2 data produces results which naively suggest more variation of cosmic expansion than would be expected in any cosmological model when the methods of Wiltshire et al. are applied. We trace this discrepancy to the fact that the distribution Malmquist biases have not been corrected for in the Cosmicflows-2 survey.

Videogrammetry is an affordable and easy-to-use technology for spatial 3D scene recovery. When applied to the civil engineering domain, a number of issues have to be taken into account. First, videotaping large scale civil infrastructure scenes usually results in large video files filled with blurry, noisy, or simply redundant frames. This is often due to higher frame rate over camera speed ratio than necessary, camera and lens imperfections, and uncontrolled motions of the camera that results in motion blur. Only a small percentage of the collected video frames are required to achieve robust results. However, choosing the right frames is a tough challenge. Second, the generated point cloud using a monocular videogrammetric pipeline is up to scale, i.e. the user has to know at least one dimension of an object in the scene to scale up the entire scene. This issue significantly narrows applications of generated point clouds in civil engineering domain since measurement is an essential part of every as-built documentation technology. Finally, due to various reasons including the lack of sufficient coverage during videotaping of the scene or existence of texture-less areas which are common in most indoor/outdoor civil engineering scenes, quality of the generated point clouds are sometimes poor. This deficiency appears in the form of outliers or existence of holes or gaps on surfaces of point clouds. Several researchers have focused on this particular problem; however, the major issue with all of the currently existing algorithms is that they basically treat holes and gaps as part of a smooth surface. This approach is not robust enough at the intersections of different surfaces or corners while there are sharp edges. A robust algorithm for filling holes/gaps should be able to maintain sharp edges/corners since they usually contain useful information specifically for applications in the civil and infrastructure engineering domain. To tackle these issues, this research presents and validates an improved videogrammetric pipeline for as built documentation of indoor/outdoor applications in civil engineering areas. The research consists of three main components: 1. Optimized selection of key frames for processing. It is necessary to choose a number of informative key frames to get the best results from the videogrammetric pipeline. This step is particularly important for outdoor environments as it is impossible to process a large number of frames existing in a large video clip. 2. Automated calculation of absolute scale of the scene. In this research, a novel approach for the process of obtaining absolute scale of points cloud by using 2D and 3D patterns is proposed and validated. 3. Point cloud data cleaning and filling holes on the surfaces of generated point clouds. The proposed algorithm to achieve this goal is able to fill holes/gaps on surfaces of point cloud data while maintaining sharp edges. In order to narrow the scope of the research, the main focus will be on two specific applications: 1. As built documentation of bridges and building as outdoor case studies. 2. As built documentation of offices and rooms as indoor case studies. Other potential applications of monocular videogrammetry in the civil engineering domain are out of scope of this research. Two important metrics, i.e. accuracy, completeness and processing time, are utilized for evaluation of the proposed algorithms.

It is projected that energy demand worldwide will double from 2009 until 2050. There is a demand for additional clean renewable energy, which can be supplied by biogas. Farm-based biogas plants exist in small numbers in Sweden; for the benefit of society it important to increase their numbers throughout the country. The aim of this report is to create the tools to allow for a competent evaluation of newly built farm-based biogas plants from an energy efficiency and environmental perspective. In this thesis data from newly built plants has been analyzed to determine mistakes that could be avoided in future expansion. Research has been performed within the bounds of a SLF financed project focusing on the role of cooperation in achieving profitability and environmental benefits in farm based biogas plants. The thesis has found that the investment cost during the technical lifetime of the plant is 11-16 kWh/MWh and 2.65 – 3.65 kg CO2-eq. per MWh. The initial investment is repaid by a factor of at least 50 during the technical lifetime of the plant. Energy ratios have been calculated for two of the plants that express the usable energy produced from each. It has been found that 29 % of Högryd’s 2 GWh in energy production becomes usable electricity and heat; at Lövsta 62 % of its 10 GWh became usable electricity and heat. A larger biogas plant benefits from a higher electrical efficiency, however, the impact of the heat utilization is significant. Replacement of 120 MWh of oil and electricity reduces the import of fossil-fuels more than 1.5 GWh of wood chips.

There is no abstract available for this dissertation.

The objective of this thesis is to successfully design, fabricate, and characterize an optimum metal-insulator-metal diode that can be used as a fast switching diode in various applications such as solar energy conversion. The improvements of this type of diode will result in rectification of a wider spectrum of AC signals to usable electricity. In this project, several proposed designs of MIM diodes were successfully fabricated and characterized. Pt-Al2O3-Al metal-insulator-metal diode was fabricated to have high asymmetry in I-V curve. Additionally, in an attempt to study the effect of material properties on MIM diode???s performance, four different combinations of MIIIIM diode were compared and discussed. Many processes were involved in the fabrication of these diodes such as E-beam evaporation, photolithography, reactive ion etching RIE, and Atomic Layer Deposition (ALD) technique. The fabricated tunneling diodes are intended to operate in the GHz regime and can also operate at higher frequencies (THz) by changing and scaling the dimensions. In addition to MIM diode work, this project attempted to engineer the contrast curve of polystyrene as a negative resist used for E-beam lithography using multi layer resist stack. If the resist stack has a very high contrast and its sensitivity differs between the various layers, it can be ideal for the fabrication of multi-level zone-plate/Fresnel lens.

Change has become a ubiquitous force in a highly globalized and interconnected world. Coastal systems are being restructured by overfishing, globalization, climate change and other factors. Further, social and ecological changes in coastal systems interact across spatial and temporal scales creating challenges that are complex, nonlinear and often difficult to predict. These new challenges have the potential to push social-ecological systems past their experienced range of variability and thus have immense consequences for the both the health of marine ecosystems and the livelihoods of hundreds of millions of people who depend on marine resources for their survival. Addressing these challenges will require collaborative efforts informed by site-specific research on the dynamics of social-ecological systems. Ultimately, this dissertation aims to contribute to efforts towards social-ecological system sustainability. Specifically, the purpose of the research is to improve our understanding of how small-scale fishers in Mozambique have adapted over time to cope with a particular set of challenges and how likely fishers are to cope effectively with future changes in their complex social-ecological systems. The dissertation is organized around four research chapters, each of which addresses a specific research objective. Detailed knowledge of historical social-ecological conditions is a critical entry point for understanding small-scale fisheries systems. While fisheries landings data are often the primary source for historical reconstructions of fisheries, reliance on data of a single type and/or from a single-scale can lead to incomplete or misleading conclusions. Moreover, in the case of many small-scale fisheries landings statistics are often incomplete and/or inaccurate. Therefore, Chapter 2 combines data from multiple sources and scales to reconstruct historical social-ecological system dynamics along the Mozambican coast. At the national scale, my analysis points towards trends of fishing intensification and decline in targeted species, and highlights the significant impact of small-scale fisheries on marine stocks. At the local scale, fishers are experiencing changes in fish abundance and distribution, as well as in their physical, social and cultural environments and have responded by increasing their fishing effort. In the context of multiple drivers of change, it has become increasingly important to identify how communities are responding to livelihood stressors. In Chapter 3, I examine how fishers are adapting to social-ecological change, and identify factors that facilitate adaptation and factors that inhibit adaptation. Primarily, fishers are adapting through intensifying their fishing efforts or by diversifying their livelihoods. Adaptation is facilitated by fishers’ groups, occupational pride and family networks. It is inhibited by limited assets, adaptive actions with negative social and ecological impacts, competition over declining resources and pervasive poverty. My data suggest that it is not the poorest fishers who are least able to adapt to change, but fishers who are locked into a declining fishery. I argue that adaptations are spatially and social differentiated and place-specific. Therefore, future adaptation initiatives aimed at strengthening the capacity of threatened communities to respond to livelihood stressors need to explicitly consider this complexity. Millions of people around the world depend on shrimp aquaculture for their income and livelihood. Yet, the phenomenal growth of shrimp aquaculture during the last two decades has given rise to considerable environmental damage and social disruption at the local level. In Chapter 4, I analyze the impacts of employment at an export-oriented shrimp farm in central Mozambique on livelihood vulnerability of farm and non-farm employees. My data indicate that shrimp farm employees are less vulnerable to chronic stressors, such a pervasive poverty, than non-farm employees, but more vulnerable to acute shocks, such as the White Spot Syndrome Virus (WSSV), associated with shrimp production than non-farm employees. I argue that future vulnerability research will need to account for this duality as aquaculture development spreads along the Western Indian Ocean. In response to the speed and magnitude of contemporary change, understanding how much disturbance communities will absorb, where social thresholds lie and what coastal community systems might look like after a threshold is crossed are critical research questions. Chapter 5 evaluates the resilience of two fishing communities in central Mozambique and forecasts the outcome of moving past socially defined thresholds. My results indicate that coastal communities are continuously absorbing multiple sources of disturbance without shifting into different states. However, a 90% decline in catch rates would represent a threshold for both communities. At Zalala Beach, fishers would respond by permanently moving to another location whereas in Inhangome, fishers would respond by changing their professions. These results contribute to our understanding of social resilience. Deliberate progress towards the goal of long-term sustainability depends on understanding the dynamics of social-ecological systems. Therefore, this dissertation aims to contribute to a growing body of theory and empirical evidence on how fishers negotiate livelihoods under conditions of rapid change and increasing vulnerability. The dissertation concludes by summarizing seven key research findings and by discussion some of the theoretical, methodological and policy contributions of my research to the literature. / Graduate / 0366

This study is concerned with the development of extended fluid-dynamic models for the prediction of micro-scale flows. When compared to classical fluid descriptions, such models must remain valid on scales where traditional techniques fail. Also, knowing that solution to these equations will be sought by numerical methods, the nature of the extended models must also be such that they are amenable to solution using computational techniques. Moment closures of kinetic theory offer the promise of satisfying both of these requirements. It is shown that the hyperbolic nature of moment equations imbue them with several numerical advantages including an extra order of spacial accuracy for a given reconstuction when compared to the Navier-Stokes equations and a reduced sensitivity to grid irregularities. In addition to this, the expanded set of parameters governed by the moment closures allow them to accurately model many strong non-equilibrium effects that are typical of micro-scale flows. Unfortunately, traditional moment models have suffered from various closure breakdowns, and robust models that offer a treatment for non-equilibrium viscous heat-conducting gas flows have been elusive. To address these issues, a regularized 10-moment closure is first proposed herein based on the maximum-entropy Gaussian moment closure. This mathematically well-behaved model avoids closure breakdown through a strictly hyperbolic treatment for viscous effects and an elliptic formulation that accounts for non-equilibrium thermal diffusion. Moreover, steps toward the development of fully hyperbolic moment closures for the prediction of non-equilibrium viscous gas flow are made via two novel approaches. A thorough study of each of the proposed techniques is made through numerical solution of many classical flow problems.

国立情報学研究所で電子化したコンテンツを使用している。

国立情報学研究所で電子化したコンテンツを使用している。

国立情報学研究所で電子化したコンテンツを使用している。