The zero-noise limit of differential equations with singular coefficients is investigated for the first time in the case when the noise is a general alpha-stable process. It is proved that extremal solutions are selected and the probability of selection is computed. Detailed analysis of the characteristic function of an exit time form on the half-line is performed, with a suitable decomposition in small and large jumps adapted to the singular drift.

Fully understanding soot formation in flames is critical to the development of practical combustion devices, which typically operate at high pressures, and fire suppression systems in space. Flames display significant changes under microgravity and high-pressure conditions as compared to normal-gravity flames at atmospheric pressure, but the exact causes of these changes are not well-characterized. As such, the effects of gravity and pressure on the stability characteristics and sooting behavior of laminar coflow diffusion flames were investigated. To study these effects, a new highly-scalable combustion modelling tool was developed specifically for use on large multi-processor computer architectures. The tool is capable of capturing complex processes such as detailed chemistry, molecular transport, radiation, and soot formation/destruction in laminar diffusion flames. The proposed algorithm represents the current state of the art in combustion modelling, making use of a second-order accurate finite-volume scheme and a parallel adaptive mesh refinement algorithm on body-fitted, multi-block meshes. An acetylene-based, semi-empirical model was used to predict the nucleation, growth, and oxidation of soot particles. Reasonable agreement with experimental measurements for different fuels and pressures was obtained for predictions of flame height, temperature and soot volume fraction. Overall, the algorithm displayed excellent strong scaling performance by achieving a parallel efficiency of 70% on 384 processors. The effects of pressure and gravity were studied for flames of two different fuels: ethylene-air flames between pressures of 0.5–5 atm and methane-air flames between 1–60 atm. Based on the numerical predictions, zero-gravity flames had lower temperatures, broader soot-containing zones, and higher soot concentrations than normal-gravity flames at the same pressure. Buoyant forces caused the normal-gravity flames to narrow with increasing pressure while the increased soot concentrations and radiation at high pressures lengthened the zero-gravity flames. Low-pressure flames at both gravity levels exhibited a similar power-law dependence of the maximum carbon conversion on pressure which weakened as pressure was increased. This dependence decayed at a faster rate in zero gravity when pressure was increased beyond 1–10 atm.

Chromium (VI) is a pervasive groundwater contaminant that poses a considerable threat to human health. Remediation techniques have focused on the reduction of the highly mobile Cr(VI) to the sparingly soluble, and less toxic, Cr(III) species. Traditionally, remediation performance has been evaluated through the measurement of Cr(VI) concentrations; however, this method is both costly and time-consuming, and provides little information regarding the mechanism of Cr(VI) removal. More recently, Cr isotope analysis has been proposed as a tool for tracking Cr(VI) migration in groundwater. Redox processes have been shown to produce significant Cr isotope fractionation, where enrichment in the ⁵³Cr/⁵²Cr ratio in the remaining Cr(VI) pool is indicative of a mass-transfer process. This thesis describes laboratory batch and column experiments that evaluate the Cr isotope fractionation associated with the reduction of Cr(VI) by various materials and under various conditions. Laboratory batch experiments were conducted to characterize the isotope fractionation during Cr(VI) reduction by granular zero-valent iron (ZVI) and organic carbon (OC). A decrease in Cr(VI) concentrations was accompanied by an increase in δ⁵³Cr values for the ZVI experiments. Data were fitted to a Rayleigh-type curve, which produced a fractionation factor α = 0.9994, suggesting a sorption-dominated removal mechanism. Scanning electron microscopy (SEM), X-ray absorption near-edge structure (XANES) spectroscopy, and X-ray photoelectron spectroscopy (XPS) indicated the presence of Cr(III) on the solid material, suggesting that reduction of Cr(VI) occurred. A series of batch experiments determined that reaction rate, experimental design, and pre-treatment of the ZVI had little to no effect on the Cr isotope fractionation. The interpretation of isotope results for the organic carbon experiments was complicated by the presence of both Cr(VI) and Cr(III) co-existing in solution, suggesting that further testing is required. A laboratory column experiment was conducted to evaluate isotopic fractionation of Cr during Cr(VI) reduction by OC under saturated flow conditions. Although decreasing dissolved Cr(VI) concentrations also were accompanied by an increase in δ⁵³Cr values, the isotope ratio values did not fit a Rayleigh-type fractionation curve. Instead, the data followed a linear regression equation yielding α = 0.9979. Solid-phase analysis indicated the presence of Cr(III) on the surface of the OC. Both the results of the solid-phase Cr and isotope analyses suggest a combination of Cr(VI) reduction mechanisms, including reduction in solution, and sorption prior to reduction. The linear characteristic of the δ⁵³Cr data may reflect the contribution of transport on Cr isotope fractionation.

China-Taiwan relations have been for decades a hot issue in East Asia as well as worldwide. The thesis researches on the China’s foreign policy toward Latin America and the Caribbean region in terms of competition with Taiwan for diplomatic recognition from the perspective of zero-sum and non zero-sum game. This study’s objective is to examine the impact of recently improved cross-Strait relations on the intensity of diplomatic competition for recognition in Latin America and the Caribbean between both sides of the Strait. Two following questions are going to be answered: Is a complete victory in diplomatic competition in Latin America and the Caribbean region a short-term goal for the PRC? How can China’s refusal of its diplomatic recognition by Paraguay be interpreted? First, literature review and theoretical framework is provided. Second, China’s and Taiwan’s policy towards Latin America and the Caribbean is researched. Third, cross- Strait rapproachement is depicted. Fourth, relations between the PRC and Taiwan after year 2005 are presented. Fifth, three case studies of Costa Rica, Panama, Paraguay are discussed. In the study I am going to look for evidence to prove that the rapprochement and the new cross-Strait diplomacy are good signs of non-zero sum game between Taiwan and China with a significant impact on diplomatic competition in Latin America and the Caribbean region. To fulfil the aim of this master thesis I am using secondary data. The scope of the paper in terms of the time period is from the establishment of the PRC but the bigger part of the paper is focused on the recent events.

Livestock grazing impacts more land than any other use. Yet knowledge of grazing impacts on native fauna is scarce. This thesis takes a predictive approach to investigating the effects of livestock grazing on Australian woodland birds, employing some novel methodological approaches and experimental designs. These include methods of analysis to handle zero-inflated data and the application of Bayesian statistics to analyse predictions based on expert opinion. The experimental designs have enabled impacts of grazing to be separated from the frequently confounding effects of other disturbances, and to consider the effect of grazing on habitat condition in the context of different surrounding land uses. A distinguishing feature of many datasets is their tendency to contain a large proportion of zero values. It can be difficult to extract ecological relationships from these datasets if we do not consider how these zeros arose and how to model them. Recent developments in modelling zero-inflated data are tested with the aim of making such methods more accessible to mainstream ecology. Through practical examples, we demonstrate how not accounting for zero-inflation can reduce our ability to detect relationships in ecological data and at worst lead to incorrect inference. The impact of grazing on birds was first examined through the elicitation of a priori predictions from 20 Australian ecologists. This expert knowledge was then used to inform a statistical model using Bayesian methods. The addition of expert data through priors in our model strengthened results under at least one grazing level for all but one bird species examined. This study highlights that in fields where there is extensive expert knowledge, yet little published data, the use of expert information as priors for ecological models is a cost effective way of making more confident predictions about the effect of management on biodiversity. A second set of a priori predictions were formulated using a mechanistic approach. Habitat structure is a major determinant of bird species diversity and livestock grazing is one mechanism by which structure is altered. Using available information on the vegetation strata utilised by each species for foraging and the strata most affected by grazing, predictions of the impact of grazing on each bird species were formulated. We found that foraging height preference was a good predictor of species’ susceptibility to grazing. This approach is a starting point for more complex predictive models, and avoids the circularity of post hoc interpretation of impact data. The confounding of grazing with tree clearing was addressed by examining the impact of pastoral management on birds in sub-tropical grassy eucalypt woodland in Southeast Queensland, where land management practices have made it possible to disentangle these effects. Changes in bird species indices were recorded across woodland and riparian habitats with and without trees across three levels of grazing, replicated over space and time. Tree removal had a dramatic influence on 78% of the bird fauna. 65% of species responded significantly to changes in grazing level and the abundance of 42% of species varied significantly with habitat, level of clearing and grazing. The impact of grazing on birds was most severe in riparian habitat. Finally, the extent to which landscape context and local habitat characteristics influence bird assemblages of riparian habitats in grazed landscapes is addressed. Over 80% of bird species responded significantly to changes in local riparian habitat characteristics regardless of context, while over 50% of species were significantly influenced by landscape context. The influence of landscape context increased as the surrounding landuse became more intensive. These results suggest that it is not enough to conserve riparian habitats alone but conservation and restoration plans must consider landscape context. The ability to predict which bird species will be most affected by grazing will facilitate the transformation of this industry into one that is both profitable and ecologically sustainable. Results from this thesis suggest that any level of commercial grazing is detrimental to some woodland birds. Habitats with high levels of grazing support a species-poor bird assemblage dominated by birds that are increasing nationally. However, provided trees are not cleared and landscape context is not intensively used, a rich and abundant bird fauna can coexist with moderate levels of grazing, including iconic woodland birds which are declining elsewhere in Australia.

Thesis (Ph. D.)--Miami University, Dept. of Educational Leadership, 2009. / Title from second page of PDF document. Includes bibliographical references (p. 87-90).

Thesis (Ph. D.)--University of California, San Diego, 2006. / Vita. Includes bibliographical references.

Orientador: Luís Carlos Origa de Oliveira / Banca: Júlio Borges de Souza / Banca: Olivio Carlos Nascimento Souto / Resumo: O acelerado desenvolvimento da eletrônica de potência vem desencadeando uma série de transformações no sistema elétrico, sendo possível destacar a constante alteração da natureza das cargas consumidoras, a proliferação da co-geração e o peso crescente de questões ambientais relacionadas à questão da geração. Grande parte das cargas atuais é composta por dispositivos não-lineares que, por muitas vezes, são a causa de problemas relacionados à qualidade da energia elétrica. Considerando a variedade da distribuição sequencial das harmônicas de corrente na utilização dos filtros passivos, destacam-se os filtros e bloqueadores eletromagnéticos, os quais têm merecido especial atenção devido à sua robustez e baixo custo de implantação. Este trabalho está particularmente direcionado à investigações relacionadas ao uso desses dispositivos que possibilitam uma atenuação do fluxo das principais componentes harmônicas que compõe as distorções harmônicas de sequência zero. Neste contexto, esta dissertação apresenta contribuições inéditas relacionadas com o desenvolvimento de modelos matemáticos no domínio da frequência para bloqueadores eletromagnéticos, e um estudo de modelos matemáticos para filtros eletromagnéticos, compondo então, o aqui denominado supressor eletromagnético de componentes de sequência zero. Apresenta-se ainda, a utilização de metodologias para análise de desempenho baseado no comportamento das componentes harmônicas sequenciais. É estabelecida uma base comparativa de natureza experimental que possibilita a avaliação do desempenho e da aderência do modelo proposto. São utilizados protótipos de baixa potência de um filtro e um bloqueador, ambos eletromagnéticos, construídos a partir de análises teóricas. Os modelos desenvolvidos são utilizados na composição de um aplicativo computacional para análise... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The accelerated development of power electronics has promoted a series of changes in the electrical system, so it is possible to highlight the constant changing of consumer loads, the proliferation of co-generation and the growing importance of environmental issues related to generation. Much of the current loads are composed of non-linear devices which, in many cases are the cause of problems related to power quality. Considering the sequential distribution variety of harmonic currents in the use of passive filters, highlight the electromagnetic filters and blockers, which have received special attention due to its robustness and low cost of deployment. This work is particularly directed to investigations related to the use of these devices which enable an attenuation of the flow of the principal harmonic components that compound the zero-sequence harmonic distortion. In this context, this work presents unedited contributions related to the development of mathematical models in the frequency domain for electromagnetic blocking, and a study of mathematical models of electromagnetic filters, making then, the here called electromagnetic zero-sequence components suppressor. It presents also, the use of methodologies for performance analysis based on the sequential behavior of harmonic components. It is established a comparison basis of experimental nature that enables the performance and adherence analysis of the model. Are used a low-power prototypes of a filter and a blocker, both electromagnetic, constructed from theoretical analysis. These models are used in the composition of a software for performance analysis and optimal project of harmonic filtering systems. This tool allows an individualized and systematic investigation of the electrical system behavior for distinct harmonic sequence components. Thus, through a detailed investigation it is possible to identify appropriated actions... (Complete abstract click electronic access below) / Mestre

With the EU's introduction of Near-zero energy requirements to be implemented in all member states by 2021, the construction sector faces a challenge in which all new building constructions are receiving tightened demands for energy conservation. In the latest edition of Boverkets Byggregler, Boverket, the Swedish National Board of Housing, has revised the energy conservation section as the first of two steps in the introduction of the Near-zero energy requirement in Sweden, where the method of calculating energy consumption is renewed and primary energy aspects are now being considered.   As it is not yet completed what the exact level of requirement for Near-zero energy is, this study applies the proposal for Swedish application of Near-zero energy requirements published by Boverket in 2015, which proposes, among other things, which primary energy factors to use for different energy carriers and use this in combination with the new method of calculating energy consumption according to the latest edition of Boverkets Byggregler.   In addition to investigating what Near-zero energy will mean, the study had as its main objective to investigate what measures can be taken to the model house, provided by Nordisk Boutveckling, to enable the building to meet the new requirements. The study was therefore designed as a parameter study, where various measures to improve the building's energy conservation were tested in the energy-calculation program VIP-Energy.   The result shows that the building, which is considered to be of a typical construction standard, is able to meet the requirement when it combines existing solar cells on the roof with a battery that can store the energy produced during the solar hours and then use this to provide the building with electricity for heating, real estate energy and for the production of tap water instead of allowing the electricity to be sold or used as household-electricity. The result also shows that installing better windows is an effective measure if the building is to meet the energy requirements with a certain margin of safety. It also turns out possible to meet the requirements by improving the building with a number of measures and using district heating as a heating method.

Computer applications are no longer local installations on our computers. Many modern web applications and services rely on an internet connection to a centralized server to access the full functionality of the application. High availability architectures can be used to provide redundancy in case of failure to ensure customers always have access to the server. Due to the complexity of such systems and the need for stability, deployments are often avoided and new features and bug fixes cannot be delivered to the end user quickly. In this project, an automation system is proposed to allow for deployments to a high availability architecture while ensuring high availability. The purposed automation system is then tested in a controlled experiment to see if it can deliver what it promises. During low amounts of traffic, the deployment system showed it could make a deployment with a statistically insignificant change in error rate when compared to normal operations. Similar results were found during medium to high levels of traffic for successful deployments, but if the system had to recover from a failed deployment there was an increase in errors. However, the response time during the experiment showed that the system had a significant effect on the response time of the web application resulting in the availability being compromised in certain situations.