This dissertation studies the causes and mechanism of power system cascading outages and proposes the improved interactive scheme between system-wide and local levels of monitoring and control to quickly detect, classify and mitigate the cascading outages in power system. A novel method for evaluating the vulnerability of individual components as well as the whole power system, which is named as weighted vulnerability analysis, is developed. Betweenness centrality is used to measure the importance of each bus and transmission line in the modeled power system network, which is in turn used to determine the weights for the weighted vulnerability index. It features fast reaction time and achieves higher accuracy when dealing with the cascading outage detection, classification and mitigation over the traditional methods. The overload problem due to power flow redistribution after one line tripped is a critical factor contributing to the cascading outages. A parallel corridor searching method is proposed to quickly identify the most vulnerable components after tripping a transmission line. The power system topology model can be simplified into state graph after searching the domains for each generator, the commons for each bus, and links between the commons. The parallel corridor will be determined by searching the links and commons in system topology graph for the given state of power system operation. During stressed operating state, either stable or unstable power swing may have impacts on distance relay judgment and lead to relay misoperation, which will result in the power system lines being tripped and as a consequence power system operating state becoming even more stressful. At the local level, an enhanced fault detection tool during power system swing is developed to reduce the chance of relay misoperation. Comprehensive simulation studies have been implemented by using the IEEE 39-bus and 118-bus test systems. The results are promising because: The results from weighted vulnerability analysis could provide better system situational awareness and accurate information about the disturbance; The results form parallel corridor search method could identify the most vulnerable lines after power re-distribution, which will give operator time to take remedial actions; The results from new travelling wave and wavelet transform based fault detection could reduce the impact of relay misoperation.

This dissertation studied new transmission line fault diagnosis approaches using new technologies and proposed a scheme to apply those techniques in preventing and mitigating cascading blackouts. The new fault diagnosis approaches are based on two time-domain techniques: neural network based, and synchronized sampling based. For a neural network based fault diagnosis approach, a specially designed fuzzy Adaptive Resonance Theory (ART) neural network algorithm was used. Several ap- plication issues were solved by coordinating multiple neural networks and improving the feature extraction method. A new boundary protection scheme was designed by using a wavelet transform and fuzzy ART neural network. By extracting the fault gen- erated high frequency signal, the new scheme can solve the difficulty of the traditional method to differentiate the internal faults from the external using one end transmis- sion line data only. The fault diagnosis based on synchronized sampling utilizes the Global Positioning System of satellites to synchronize data samples from the two ends of the transmission line. The effort has been made to extend the fault location scheme to a complete fault detection, classification and location scheme. Without an extra data requirement, the new approach enhances the functions of fault diagnosis and improves the performance. Two fault diagnosis techniques using neural network and synchronized sampling are combined as an integrated real time fault analysis tool to be used as a reference of traditional protective relay. They work with an event analysis tool based on event tree analysis (ETA) in a proposed local relay monitoring tool. An interactive monitoring and control scheme for preventing and mitigating cascading blackouts is proposed. The local relay monitoring tool was coordinated with the system-wide monitoring and control tool to enable a better understanding of the system disturbances. Case studies were presented to demonstrate the proposed scheme. An improved simulation software using MATLAB and EMTP/ATP was devel- oped to study the proposed fault diagnosis techniques. Comprehensive performance studies were implemented and the test results validated the enhanced performance of the proposed approaches over the traditional fault diagnosis performed by the transmission line distance relay.

<p>Cascading Web Services represent a collection of services offered in a system consisting of multiple devices and multiple interacting platform independent networks. ‘Cascading’ enables Web Services to exploit access in diverse environments without manual intervention. The aim of this thesis is to investigate how Mobile Web Services interact with multiple other Web Services by allowing the generated content to cascade. These services are demonstrated as a technical design solution, in a number of cases within the field of Learning technologies. Communication among devices is preceded using request-response commands by cascading these commands between different Web Services that are self-contained and independent on their context or state.</p><p>The system signifies a typical Service Oriented Architecture (SOA) based on a distributed system. Cascading Web Services involve multiple transport networks including Bluetooth Technology, GPRS, Wi-Fi, and Wired Networks. Whereas the protocol of this communication is to bridge Wired and Wireless networks for data transactions, specifically from a Bluetooth location-based network. A number of particular cases will be illustrated in the context of ‘educational outdoor activities’, to demonstrate how the system solution works involving users.</p>

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In the refining industry, the cost of a power system interruption is dominated by an associated loss of production. Power distribution within a refinery includes a set of production units within a highly inter-dependent process, where the outage of a single unit affects the production of additional units. This thesis proposes a method to quantify the impact of this cascading effect, called the criticality enhancement function, in which a process reliability model is introduced to link electrical outage cut-sets with lost production. Power system criticality is analyzed using four different approaches to the calculation of annual expected impact from load point interruptions on a case study of the 125,000 barrel-per-day Petro-Canada Edmonton Refinery. This thesis demonstrates how employment of the proposed technique, with its marriage of electrical and process reliability models, enables the most accurate estimation of the impact of power system interruptions.

The three essays of this dissertation inform tax policy design. It is a compilation of empirical and experimental research work. The first and the second essays explore the performance of a recent tax policy reform at the sub-national level in India in terms of revenue efficiency as well as economic efficiency. India is among the only three countries in the world to have adopted a sub-national VAT. Therefore, empirically examining its performance not only improves the understanding of this important tax policy reform but also informs tax policy decision-making at the sub-national level in other developing countries. India transitioned to the state-level VAT between the years 2003 and 2008. Among other things, it was expected to achieve revenue growth and decrease tax cascading on commodities by improving economic efficiency of the indirect tax system. In the first essay, I model the impact of the VAT on revenue by adding revenue dependent administrative and compliance costs associated with taxation to an existing model developed by Keen and Lockwood (2010). The theoretical results show that replacing one type of indirect tax with another improves long-run revenue efficiency only if there is a net decrease in the administrative, compliance and distortionary costs of taxation at the margin. I then compile a unique state-level dataset for the years 1990 to 2010 to determine changes in the long-run revenue efficiency from the use of the VAT. This essay contributes to the literature by extending an existing revenue efficiency model and testing it in the unique situation of India’s sub-national VAT. The results reveal a significant improvement in the long-run revenue efficiency of the sales tax instrument used by state governments. The model implies this improvement is driven by a net fall in the marginal taxation costs from the use of the state-level VAT. This finding has important implications on the role of a sub-national VAT in the future as an effective tax instrument in the developing countries. The second essay appeals to the general theory of tax incidence which suggests that a VAT will have less impact on prices than a traditional turnover tax because the VAT does not “get stuck” in the production process as a turnover tax does. The impact should be larger for goods that have more components to the production process as the tax then “touches” more of the final product. In this essay I measure the change in the level of tax cascading with VAT by using multiple waves of the state- and household-level expenditure surveys. Specifically I test the impact of the VAT on the real consumption of households on a variety of consumption goods. I find the biggest significant decrease in the tax cascading burden of the long-term durable goods which essentially involve the maximum production components. This result is found in the 18 more developed states of India which are the focus of the empirical analysis due to data constraints. The third essay is an experimental research which looks at the influence of institutions on the economic burden of an excise tax. The traditional long-run tax incidence theory establishes that the economic incidence of an excise tax is independent of the assignment of the liability to pay tax. However, the theory is silent on the possible effects of the market institutions on tax incidence. Since all markets need an institution to function and every market institution has its own unique price and quantity determination property, it is important to understand its bearings on the incidence of taxes. Existing experimental research has tested economic incidence under many different market institutions but no previous research systematically analyzes and compares the incidence of a unit tax under two important market institutions we deal with in everyday life. One of these institutions is posted offer which dominates the consumer goods markets in developed countries and the other is double auction which is frequently observed in developing countries. I report a significant impact of these market institutions on tax incidence. In particular, I find that consumers bear a much higher burden of a unit tax in the posted offer markets as compared to the double auction markets and their burden further increases when the liability to pay the tax is on the seller.

Esta tese identificou vários aspectos importantes da estrutura trófica e dinâmica de nutrientes em ecossistemas aquáticos sujeitos a perturbações externas, tais como mudanças no nível da água, aumento de carga de nutrientes e matéria orgânica, biomanipulação e clima. Para descrever tais efeitos sobre a estrutura trófica, um complexo modelo ecológico, com base em processos físicos, químicos e biológicos, foi desenvolvido e aplicado em ecossistemas aquáticos tropicais, subtropicais e temperados. Em tais aplicações, uma análise integrada foi empregada considerando a transferência de impactos da bacia para o ecossistema, com a finalidade de entender a real dinâmica dos ecossistemas aquáticos. As simulações revelaram importantes aspectos sobre a estrutura e funcionalidade dos ecossistemas frente as pertubações. Por exemplo, a lagoa Mangueira, um lago raso subtropical no sul do Brasil, pode oscilar entre dois estados alternativos estáveis (alta e baixa transparência da água), dependendo da concentração de ortofosfato e da túrbidez. Foi sugerido também que podem ocorrer profundas alterações na composição do fitoplâncton com a aumento sistemático da concentração de ortofosfato. Foram constatados significativos gradientes horizontais e verticais na estrutura trófica da lagoa Mangueira, indicando a importância de considerar a heterogeneidade espacial em grandes lagos para melhorar a compreensão dos processos ecológicos e padrões. Cenários críticos de simulação indicaram que o aumento da carga de nutrientes afeta negativamente a transparência da água, diferentemente do efeito de mudanças climáticas. Pequenas alterações na estrutura trófica causadas por esses fatores indicam uma forte resistência da lagoa Mangueira. O modelo ecológico também foi útil para descrever a dinâmica do ecossistema, antes e depois da biomanipulação do lago Engelsholm localizado na Dinamarca. Nesse caso, o modelo conseguiu razoavelmente prever a mudança para um estado de alta transparência da após a biomanipulação, entretanto a mudança na composição do fitoplâncton foi muito mais difícil de representar. Além disso, aplicações mais simples também auxiliaram o processo de tomada de decisão e planejamento. A modelagem ecológica aplicada em ecossistemas aquáticos mostrou ser uma alternativa promissora para a gestão integrada dos recursos naturais. / This thesis identified several important features of the trophic structure and dynamics of nutrients in ecosystems subjected to external disturbances such as changes in the water level, nutrient and organic matter loading, fish communities and climate. To describe such effects on trophic structure, a complex ecological model, based on physical, chemical and biological processes has been developed and applied in tropical, subtropical and temperate aquatic ecosystems. In such applications, an integrated analysis was employed considering the transfer of impacts from the watershed to the ecosystem, in order to bring closer the understading of the ecosystem dynamics. Simulations revealed important features about system structure and functionality in front of disturbances. For instance, lake Mangueira a subtropical lake in Southern Brazil can oscilate between two alternative steady stables (clear or turbid water), depending orthophosphate concentration and water transparency. It was also suggested that can occurs profound changes in phytoplankton composition from increase of orthophosphate concentration. Horizontal and vertical gradients in the trophic structure are notable in lake Mangueira, indicating the importance to consider spatial heterogeneity in large lakes to improve understanding of ecological processes and patterns. Simulation scenarios indicated that increased nutrient loading negatively affects water transparency, differently from climate changes. Slight changes in trophic structure caused by those factors indicate a strong resistence of the lake Mangueira. The ecological model also was useful to describe the ecosystem dynamics before and after biomanipulation of lake Engelsholm located in Denmark. In that case, the model could reasonably well predict a shift to a clear water state, but the changed composition of phytoplankton functional groups was much more hard to represent. Furthermore, simpler applications also provided support for decision making and planning in the ecosystem. Ecological modeling applied in aquatic ecosystems showed be a promising alternative towards the integrated management of natural resources.

xx, 214 p. : ill. (some col.) / Intramolecular cascading Michael additions have the ability to transform simple, symmetric substrates into densely functionalized compounds containing new ring structures and chiral centers. The Rauhut-Currier (RC) reaction, also known as the vinylogous Morita-Baylis-Hillman reaction, utilizes this type of reactivity by cyclizing tethered, activated alkenes using phosphine or thiolate catalysis. This dissertation describes the expansion of the scope of the RC reaction, the introduction and importance of co-catalysts to cascading Michael additions, the development of the first amine-catalyzed RC reaction, and the transformation of cyclization products into fused, polycyclic aromatic compounds. Chapter I reviews the development and applications of the Rauhut-Currier reaction. Chapter II describes the regioselective synthesis of di-substituted indenes and introduces phenol as a rate- and selectivity-enhancing co-catalyst. Although tertiary amine nucleophiles were found to be inferior to phosphines as cyclization catalysts, chapter III discusses the ability of unhindered primary and secondary amines to undergo a diastereoselective, cascading aza-Michael-Michael addition to yield a wide variety of amino-indanes in the presence of an acid catalyst. Recognizing the importance of protic environments and small nucleophiles, the development of the first amine-catalyzed intramolecular RC is introduced in chapter IV. Chapter V describes the conversion of methyl ketone-substituted indenes to fluorene derivatives via an intramolecular aldol reaction. Chapter VI describes the serendipitous discovery and synthesis of indenopyrylium salts. Chapter VII details the novel production of indenopyridines from di-substituted indenes. Lastly, chapter VIII provides a summary and suggests future directions for this research. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Shih-Yuan Liu, Chairperson; Kenneth Doxsee, Advisor; David Tyler, Member; Michael Haley, Member; A. Dana Johnston, Outside Member

Esta tese identificou vários aspectos importantes da estrutura trófica e dinâmica de nutrientes em ecossistemas aquáticos sujeitos a perturbações externas, tais como mudanças no nível da água, aumento de carga de nutrientes e matéria orgânica, biomanipulação e clima. Para descrever tais efeitos sobre a estrutura trófica, um complexo modelo ecológico, com base em processos físicos, químicos e biológicos, foi desenvolvido e aplicado em ecossistemas aquáticos tropicais, subtropicais e temperados. Em tais aplicações, uma análise integrada foi empregada considerando a transferência de impactos da bacia para o ecossistema, com a finalidade de entender a real dinâmica dos ecossistemas aquáticos. As simulações revelaram importantes aspectos sobre a estrutura e funcionalidade dos ecossistemas frente as pertubações. Por exemplo, a lagoa Mangueira, um lago raso subtropical no sul do Brasil, pode oscilar entre dois estados alternativos estáveis (alta e baixa transparência da água), dependendo da concentração de ortofosfato e da túrbidez. Foi sugerido também que podem ocorrer profundas alterações na composição do fitoplâncton com a aumento sistemático da concentração de ortofosfato. Foram constatados significativos gradientes horizontais e verticais na estrutura trófica da lagoa Mangueira, indicando a importância de considerar a heterogeneidade espacial em grandes lagos para melhorar a compreensão dos processos ecológicos e padrões. Cenários críticos de simulação indicaram que o aumento da carga de nutrientes afeta negativamente a transparência da água, diferentemente do efeito de mudanças climáticas. Pequenas alterações na estrutura trófica causadas por esses fatores indicam uma forte resistência da lagoa Mangueira. O modelo ecológico também foi útil para descrever a dinâmica do ecossistema, antes e depois da biomanipulação do lago Engelsholm localizado na Dinamarca. Nesse caso, o modelo conseguiu razoavelmente prever a mudança para um estado de alta transparência da após a biomanipulação, entretanto a mudança na composição do fitoplâncton foi muito mais difícil de representar. Além disso, aplicações mais simples também auxiliaram o processo de tomada de decisão e planejamento. A modelagem ecológica aplicada em ecossistemas aquáticos mostrou ser uma alternativa promissora para a gestão integrada dos recursos naturais. / This thesis identified several important features of the trophic structure and dynamics of nutrients in ecosystems subjected to external disturbances such as changes in the water level, nutrient and organic matter loading, fish communities and climate. To describe such effects on trophic structure, a complex ecological model, based on physical, chemical and biological processes has been developed and applied in tropical, subtropical and temperate aquatic ecosystems. In such applications, an integrated analysis was employed considering the transfer of impacts from the watershed to the ecosystem, in order to bring closer the understading of the ecosystem dynamics. Simulations revealed important features about system structure and functionality in front of disturbances. For instance, lake Mangueira a subtropical lake in Southern Brazil can oscilate between two alternative steady stables (clear or turbid water), depending orthophosphate concentration and water transparency. It was also suggested that can occurs profound changes in phytoplankton composition from increase of orthophosphate concentration. Horizontal and vertical gradients in the trophic structure are notable in lake Mangueira, indicating the importance to consider spatial heterogeneity in large lakes to improve understanding of ecological processes and patterns. Simulation scenarios indicated that increased nutrient loading negatively affects water transparency, differently from climate changes. Slight changes in trophic structure caused by those factors indicate a strong resistence of the lake Mangueira. The ecological model also was useful to describe the ecosystem dynamics before and after biomanipulation of lake Engelsholm located in Denmark. In that case, the model could reasonably well predict a shift to a clear water state, but the changed composition of phytoplankton functional groups was much more hard to represent. Furthermore, simpler applications also provided support for decision making and planning in the ecosystem. Ecological modeling applied in aquatic ecosystems showed be a promising alternative towards the integrated management of natural resources.

Cascading Web Services represent a collection of services offered in a system consisting of multiple devices and multiple interacting platform independent networks. ‘Cascading’ enables Web Services to exploit access in diverse environments without manual intervention. The aim of this thesis is to investigate how Mobile Web Services interact with multiple other Web Services by allowing the generated content to cascade. These services are demonstrated as a technical design solution, in a number of cases within the field of Learning technologies. Communication among devices is preceded using request-response commands by cascading these commands between different Web Services that are self-contained and independent on their context or state. The system signifies a typical Service Oriented Architecture (SOA) based on a distributed system. Cascading Web Services involve multiple transport networks including Bluetooth Technology, GPRS, Wi-Fi, and Wired Networks. Whereas the protocol of this communication is to bridge Wired and Wireless networks for data transactions, specifically from a Bluetooth location-based network. A number of particular cases will be illustrated in the context of ‘educational outdoor activities’, to demonstrate how the system solution works involving users.