Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [212]-293).

An understanding of extreme waves is important in the design and analysis of offshore structures, such as oil and gas platforms. With the increase of interest in the shipping of LNG, the design of import and export terminals in coastal water of slowly varying intermediate depth requires accurate analysis of steep wave shoaling. In this thesis, data from laboratory experiments involving random wave simulations on very gentle slopes have been analysed in terms of a model of large wave events, and the results interpreted by observation of the shape and magnitude of the large wave events. The auto-correlation function of the free surface elevation time histories, called NewWave, has been calculated from the wave spectrum and shown to fit very well up to the point where waves start to break (when compared to the ‘linear’ surface elevation time history). It has been shown that NewWave is an appropriate model for the shape of the ‘linear’ part of large waves provided kd > 0.5. A Stokes-like expansion for NewWave analysis has been demonstrated to match the average shape of the largest waves, accounting for the dominant vertical asymmetry. Furthermore, an appropriate local wave period derived from NewWave has been inserted into a Miche-based limiting criterion, using the linear dispersion equation, to obtain estimates for the limiting wave height. Overall, the analysis confirms the Miche-type criterion applies to limiting wave height for waves passing over very mild bed slopes. A derivation of general Green-Naghdi (GN) theory, which incorporates non-linear terms in its formulation, is also presented. This approach satisfies the boundary conditions exactly and approximates the field equations. The derived 2-dimensional vertical GN Level 1 model, capable of simulating steep waves on varying water depth, is validated against solitary waves and their interactions, and solitary waves on varying water depth and gives good qualitative agreement against the KdV equation. The developed and validated numerical model is used to simulate focussed wave groups on both constant depth and gentle slope. In general, the behaviour of waves simulated by the numerical model is very similar to that observed in the experimental data. There is evidence of vertical asymmetry as the water depth is reduced, owing to the non-linearity. Although the main physics is still controlled by linear dispersion, the higher order harmonics become increasingly important for shoaling waves. The numerical results also show a slope-induced wave set-up that keeps on increasing in amplitude as the wave group travels on the gentle slope.

Thesis (Ph. D.)--University of Adelaide, 1995. / Includes bibliographical references (p. 474-514).

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Civil and Environmental Engineering." Includes bibliographical references (p. 79-80).

Orientador: Paulo Vatavuk / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-26T05:26:13Z (GMT). No. of bitstreams: 1 SouzaJunior_JosedoCarmode_M.pdf: 6575151 bytes, checksum: ab067f578f53eb5139546f4f0f2c13e2 (MD5) Previous issue date: 2014 / Resumo: O volume global de perdas de água é significativo. Cada ano, mais de 32 bilhões de m3 de água tratada são perdidos por vazamentos em redes de distribuição. Tendo em vista a complexidade dos sistemas de abastecimento de água, a divisão em sistemas menores permite analisar individualmente cada componente do sistema e definir ações que proporcionem uma gestão mais adequada. O presente trabalho tem por objetivo apresentar as ferramentas para gestão de perdas de água através da utilização dos Distritos de Medição e Controle (DMC's), que são áreas menores e mais gerenciáveis e possibilitam um controle efetivo de pressões e vazões nas redes de distribuição, proporcionando a redução dos volumes de água perdidos. A metodologia de utilização dos DMC's é internacionalmente aceita como uma das melhores práticas para redução de perdas de água, entretanto, sua aplicação é relativamente recente no campo de redes de distribuição. As áreas de abrangência dos DMC's são definidas tomando-se por base parâmetros como número de ligações de água, requisitos de pressão mínima e máxima, nível atual de vazamentos, limites do sistema de abastecimento, como áreas de bombeamento e áreas de válvulas redutoras de pressão, ou limites definidos através de estudos que identificam locais estratégicos para implantação de medidores de vazão. Após a implantação dos DMC's é realizado o gerenciamento das perdas de água, através do monitoramento das pressões e vazões. Os efeitos positivos do gerenciamento das pressões são reais para diminuir as perdas de água através da redução de pressões. A medição de vazão em redes de distribuição é outro fator importante no controle de perdas de água, pois sua correta utilização tem influência direta nos índices de perdas, onde é possível identificar áreas com níveis elevados de vazamentos. O trabalho apresenta um estudo de caso da implantação de DMC's no município de Bragança Paulista, operado pela Companhia de Saneamento Básico do Estado de São Paulo ¿ SABESP, demonstrando as ferramentas utilizadas para o gerenciamento das pressões e vazões, e propõe uma metodologia para intensificar os trabalhos de redução de perdas em DMC's, através de um sistema de informações geográficas, indicadores de desempenho adotados pela International Water Association (IWA) e da elaboração do balanço hídrico com o software gratuito do Banco Mundial WB-EasyCalc. Os resultados demonstram que a ferramenta possibilita uma gestão efetiva, através de uma ação mais focada nos DMC's que apresentam os maiores índices de perdas de água. Palavras-chave: Distrito de Medição e Controle (DMC), Rede de Distribuição de Água, Perdas de Água / Abstract: The overall volume of water losses is considerable. Each year, more than 32 billion m3 of drinking water are lost through leakage in water distribution networks. Given the complexity of water supply systems, the division into smaller structures allows the analysis of individual components and define actions that provides better management. This study presents the tools for managing water losses using District Metered Areas (DMAs), which are smaller and more manageable areas and enable effective control of pressures and flows in water distribution networks, providing a reduction in the volume of water losses. The methodology of using DMAs is internationally accepted as one of the best practices for reducing water losses, however, it¿s application is relatively new in the field of water distribution networks. The areas covered by the DMAs are defined by taking into consideration parameters like number of connections, minimum and maximum pressure requirements, current leakage level, limits of the water supply system as pump areas, and pressure reducing valves areas, or boundaries defined by studies that identify strategic locations for deployment of flowmeters. After having established DMAs, management of water losses is performed supervising the pressures and flow rates. The pressure management result in positive effects reducing water losses through reduced pressures. The measurement of flow in water distribution networks is another important factor in water loss control, because it¿s proper use has a direct influence on loss rates, where can identify areas with high levels of leakage. This study presents a case study about implementation of DMAs in the city of Bragança Paulista, operated by the Water Sanitation & Company of the State of São Paulo - SABESP, showing the tools used to manage pressures and flow rates, and proposes a methodology to improve works about water losses reduction in DMAs, through a Geographic Information System, performance indicators used by the International Water Association (IWA) and the development with the free water balance software from the World Bank, WB EasyCalc. The results shows that the tool allows effective management of water losses through actions in DMAs wich have the highest water losses. Keywords: District Metered Area (DMA), Water Distribution Network (WDN), Water Loss / Mestrado / Recursos Hidricos, Energeticos e Ambientais / Mestre em Engenharia Civil

Orientador: José Gilberto Dalfre Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-21T12:04:12Z (GMT). No. of bitstreams: 1 Diniz_AldoRobertoSilva_M.pdf: 2375146 bytes, checksum: 0af05ce5634ce83e9d2b7af8c30a2179 (MD5) Previous issue date: 2012 / Resumo: O presente trabalho apresenta uma avaliação de um método para o controle de perdas físicas de água, caracterizando-as, de maneira a priorizar as ações de combate e redução de perdas físicas. Para o desenvolvimento do trabalho, foi realizada uma ampla revisão bibliográfica, em que é apresentada a conceituação geral sobre perdas de água, suas causas e ocorrências, indicadores, ações para redução, e uma abordagem detalhada quanto aos métodos existentes para avaliação de perdas e as ferramentas disponíveis. O método de avaliação para o controle das perdas físicas baseia-se no balanço hídrico, utilizando o software gratuito desenvolvido pela AWWA (American Water Works Association, Water Audit 4.0) e foi aplicada no estudo de caso do sistema de abastecimento de água da Região Metropolitana de São Paulo (RMSP), denominado setor Casa Verde. Foram levantados os dados de controle do sistema e realizados os ensaios de campo, com medições de pressão para determinação do local dos vazamentos não visíveis, auxiliando na sua caracterização e permitindo a priorização das ações de combate às perdas físicas. Os resultados do diagnóstico da localização das perdas foram analisados, desenvolvendo-se uma estratégia para a redução de perdas físicas / Abstract: This paper presents an evaluation method for the control of physical losses of water, aiding in determining the profile of losses, allowing for better prioritization of actions to combat and reduce physical losses. For the development of this evaluation was performed an extensive literature review, where it shows a general concept on water loss, its causes and events, indicators, actions to reduce, and as a comprehensive approach to existing methodologies to assess losses and tools available. The assessment of physical losses presented here is the beginning through the water balance, using free software developed by AWWA (American Water Works Association, Water Audit 4.0), was applied to the water supply system in the Metropolitan Region of São Paulo (MRSP) industry called Casa Verde. Data were the basic control system and field trials carried out with pressure measurements and tests to determine the location of leaks not visible. The assessment was applied in a supply sector of the northern area of the metropolitan region, with characteristics of controlled pressure. Diagnostic results of the losses were consistent with expectations. Depending on the results for this sector should be developed a specific strategy for the reduction of physical losses and method for controlling physical losses of water, aiding in determining the profile of losses, allowing for better prioritization of actions to combat and reduce physical loss / Mestrado / Recursos Hidricos, Energeticos e Ambientais / Mestre em Engenharia Civil

To achieve sustainable production of H2 fuel through water splitting, low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are required to replace Pt and IrO2 catalysts. Here, for the first time, we present the interface engineering of novel MoS2/Ni3S2 heterostructures, in which abundant interfaces are formed. For OER, such MoS2/Ni3S2 heterostructures show an extremely low overpotential of ~218 mV at 10 mA cm-2, which is superior to that of the state-of-the-art OER electrocatalysts. Using MoS2/Ni3S2 heterostructures as bifunctional electrocatalysts, an alkali electrolyser delivers a current density of 10 mA cm-2 at a very low cell voltage of ~1.56 V. In combination with density function theory (DFT) calculations, this study demonstrates that the constructed interfaces synergistically favor the chemisorption of hydrogen and oxygencontaining intermediates, thus accelerating the overall electrochemical water splitting.