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Economia e Gestão do Ambiente / Master in Environmental Economics and Management / First and foremost, this research project develops a framework for analyzing electric system operators ( ESOs ). A deep literature survey is invoked to inventory the responsibilities of these institutions; then, a graphical model is developed so as any type of operator can be represented. This framework is useful to create comparisons between operators and understand the different nature of the responsibilities they are charged with, in connection with the particularities of their electric sectors. This framework was developed with the precise aim to benchmark the Brazilian operator against similar entities, yet it can be used for any country with an at least functionally unbundled ESO. Canada, Norway and Colombia were chosen due to the high percentage of hyroelectricity in their electricity generation capacity and production matrixes, a characteristic that is similar to the Brazilian case. Nevertheless, the study finds that the Brazilian operator s particularities owe mainly to the uniqueness of the electricity context, despite a few transaction costs between institutions than can possibly be reduced.

A future expansion of wind power in the Nordic power system makes the balancing for the transmission system operator Svenska Kraftnät (SvK) more complicated. Up to the hour of delivery the balance responsible parties’ (BRP) makes prognoses and plans, for consumption and production, to help maintain the balance in the electrical grid. How well this is accomplished is affected by the setup of the market design. Therefore SvK has proposed the following possible changes in market design:   Increase the imbalance costs Intensify the regulation of imbalances Increase the temporal resolution on the different markets Present the prices for balancing power in real-time Modify the balancing market to simplify auction of consumption bids A mapping over the BRPs’ processes within planning and trading on the day-ahead, intra-day, and the balancing market has been performed in this thesis. This mapping shows that the actual processes differ from the theoretical. How they differ depends on the size of the BRP, hence a categorization has been carried out with regards to their share of production in the electrical grid. The results show that the different market changes affect the categories in different ways as well.   The analysis shows that increased imbalance costs, intensified regulation of imbalances and modification of the balancing market to simplify auction of consumption bids are the most beneficial changes from the systems perspective. Finally a discussion covers how these changes could be conducted, along with the possible implications that might occur. Implications could be increased electricity prices and economies of scale for larger BRP’s.

Unipolar depression is a leading cause of disability and overall burden of disease for millions of individuals across the world. Depressive symptoms (e.g., depressed mood, anhedonia, fatigue, feelings of worthlessness, difficulties concentrating, etc.) can drastically affect an individual's life leading to occupational, social, and personal impairment. Past research shows significant ethnic and racial differences in depression rates and treatment. Moreover, previous literature has also begun to explore the multidimensional nature of depression, investigating its occasion-like (or episodic) and trait-like (or stable) factors. However, prior studies have not explored differences in occasion and trait depression by race or ethnicity, nor have they explored these questions in nurses, a group that faces substantial workplace stressors. To redress these gaps, the current study investigated trait and occasion depression in a large sample of nurses (N = 390) tracked across 12 months and aimed to understand whether trait versus occasion rates of depression differed by racial and ethnic minority status. Findings indicated substantially more trait depression (65.93%) than occasion depression (34.11%) across the year in nurses. However, there were no significant differences based on racial and ethnic minority status. Results highlight the importance of understanding depression as a much more stable aspect of an individual's personality, instead of merely viewing it as a direct response to changes in an individual's external environment. Additionally, findings suggest that focusing on adaptation of more long-term skills to target trait-like depression may be more helpful for nurses experiencing depression.

published_or_final_version / Architecture / Master / Master of Landscape Architecture

[pt] Para combater as alterações climáticas, os sistemas energéticos modernos estão a passar por uma transição baseada na descarbonização, envolvendo uma vasta implantação de fontes de energia renováveis e a electrificação das sociedades. Para que esta transição seja bem sucedida, vários desafios associados à produção de energia renovável precisam de ser abordados nas operações do sistema energético. Esses desafios decorrem da alta variabilidade de produção, juntamente com previsibilidade e controlabilidade limitadas, levando a necessidades de flexibilidade nas operações do sistema de energia. O fluxo de potência ideal (OPF) e o comprometimento da unidade (UC) estão entre as ferramentas computacionais mais importantes para os operadores do sistema determinarem o estado do sistema de potência. Este cálculo é realizado para otimizar diversas decisões na rede, para despachar os componentes da rede e para reconfigurá-los. Além disso, o cálculo é utilizado para precificar os serviços prestados por geradores de grande escala e, progressivamente, por entidades descentralizadas como famílias e pequenas empresas que, além de consumirem, também geram e armazenam energia, e assim, têm um papel no equilíbrio energético através de sua flexibilidade. Várias simplificações são feitas no OPF e no UC para lidar com a carga computacional dos modelos, que tende a ser elevada para sistemas realistas. A imprecisão do modelo devido à simplificação das equações de fluxo de potência ou ao ignorar a estocasticidade, está causando cada vez mais altos custos para as operações do sistema, à medida que a situação real se desvia da previsão, implicando ações dispendiosas por parte dos operadores do sistema em tempo real. Esta tese centra-se nos desafios das operações dos sistemas de energia modernos, tais como gestão coordenada de congestionamento e tensão, programação de energia e reservas, bem como cálculo de preços. Em primeiro lugar, a tese constrói métodos e algoritmos para melhorar a capacidade computacional e a precisão do modelo para problemas de UC e OPF com restrita de rede e corrente alternada (AC) através do desenvolvimento de uma aproximação melhorada das leis físicas que governam os fluxos de potência. Em segundo lugar, aplica estes métodos e algoritmos ao problema de coordenação entre múltiplos Operadores de Redes de Distribuição (DSO) e Operadores de Redes de Transmissão (TSO), introduzindo novas técnicas de optimização descentralizada para gerir problemas de congestionamento e tensão, bem como abordar aspectos de troca de informação de rede. Por fim, a tese propõe novos mecanismos de precificação, abordando endogenamente as decisões operacionais não convexas de energia e programação de reservas para o planejamento do dia seguinte, considerando a estocasticidade da geração de energia renovável. Os benefícios computacionais e de precisão são ilustrados em estudos de caso, empregando diversas métricas desenvolvidas. / [en] To counter climate change, modern power systems are undergoing a decarbonisation-based transition involving vast deployment of renewable energy sources and electrification of societies. For this transition to succeed, various challenges associated with renewable power production need to be addressed in power system operations. These challenges stem from high output variability along with limited predictability and controllability, leading to flexibility needs in power system operations. Optimal power flow (OPF) and unit commitment (UC) are amongst the most important computational tools for system operators to determine the state of the power system. This computation is performed to optimise various decisions on the grid, to dispatch the components in the network, and to reconfigure them. Additionally, the computation is used to price the services provided by large scale generators and, progressively, by decentralised entities such as households and small enterprises which, apart from consuming, also generate and store power, and thus, have a role in energy balancing through their flexibility. Various simplifications are made in OPF and UC to tackle the computational burden of the models, which tends to be high for realistic systems. Model inaccuracy due to simplification of power flow equations or ignoring stochasticity, is increasingly causing high costs for system operations, as the real situation deviates from the forecast implying costly actions by system operators in real-time. This thesis focuses on challenges in modern power system operations, such as coordinated congestion and voltage management, energy and reserve scheduling as well as price computation. Firstly, the thesis constructs methods and algorithms to enhance computational capability and model accuracy for Alternating Current (AC) Network-Constrained UC and OPF problems through devising an improved approximation of the physical laws governing power flows. Secondly, it applies these methods and algorithms to the coordination problem amongst multiple Distribution System Operators (DSO) and Transmission System Operators (TSO), introducing novel decentralised optimisation techniques for managing congestion and voltage problems as well as addressing network information exchange aspects. Finally, the thesis proposes new pricing mechanisms, endogenously tackling the non-convex operational decisions for energy and reserve scheduling for day-ahead planning, considering stochasticity of renewable energy generation. Computational and accuracy benefits are illustrated in case studies by employing various metrics developed.

In Taiwan area, the mortality rates at all ages have decreased since the end of World War II, and the life expectancy of people has increased from 62 in 1950's to 75 in 2000, which is an increase of 21%. The mortality improvement of the elderly (i.e. people ages 65 and over) is especially significant, which effects in the rapid population aging in Taiwan area. For example, the proportion of the elderly has increased from 6.14%in 1990 to 8.52% in 2000. On one hand, the prolonged life span for an individual means a longer period of retirement life and thus a larger retirement fund. On the other hand, a longer life for the government is equivalent to a more thorough social system for the elderly. Therefore, a reliable mortality rates projection is essential to both personal financial and social welfare planning. 　　In this study, we have two main objectives: First, we explore some frequent used models, such as Lee-Carter, multivariate regression and principal component methods. We use the data between 1950 to 1995 as the pilot data and 1996 to 2000 as the test data to judge which method has the smallest prediction error. In addition, based on computer simulation, we also evaluate the performance of the estimation methods for the Lee-Carter method. The second part (and the other objective) of this study is to explore the effect of mortality improvement on the pure premium of annuity insurance. In particular, we calculate the pure premium of the annuity under the best model acquired from the first part, and compare those under 1989 TSO and other life tables. We found that the pure premiums under current life tables are under estimated, which may cause the insolvency of insurance companies.

Indiana University-Purdue University Indianapolis (IUPUI) / The Tso Morari terrane within the Himalayan orogenic belt underwent ultrahigh-pressure (UHP) coesite-eclogite metamorphism due to northward subduction of the Indian continent under the Eurasian continent during the early Eocene. In this study we optimized a best protocol for thermodynamically modelling pressure-temperature (P-T) paths of high-grade metabasites using the Tso Morari eclogite as a case study through evaluating the effects of employing commonly used thermodynamic modeling techniques (e.g., programs, thermodynamic datasets, a-X relations). A “fishhook” shaped clockwise P-T path was obtained with a peak pressure of ~28.5 kbar at ~563 °C, followed by a peak temperature of ~613 °C at ~24.5 kbar. The peak pressures predicted by modelling protocols are consistent with the conventional thermobarometry results and petrographic observations from the Tso Morari eclogites. Secondly, thermodynamic modelling using P-M(H2O) pseudosections on Tso Morari UHP rocks indicates three distinct fluid events during the prograde and retrograde metamorphism. Fluid Event 1 caused the fluid-assisted homogenization of prograde garnet cores in eclogite at ~18.5 kbar and ~555 °C; Fluid Event 2 is evidenced by the formation of poikiloblastic epidote (~23.5 kbar and ~610 °C, at the expense of lawsonite) and amphibole (from ~19.0 to ~14.5 kbar at ~610 °C, at the expense of omphacite and talc), and symplectite association (~8.7 kbar and ~625 °C) in the eclogite matrix without external fluid supply. Fluid Event 3 was determined through modelling the amphibolitization of eclogites with external fluid infiltration at ~9.0–12.5 kbar and ~608 °C. This fluid phase most likely derived from the mixing of dehydrated host orthogneiss and/or metasediments during exhumation through the amphibolite-facies zone in the subduction channel. This study demonstrates the need for using careful petrographic observations in parallel with thermodynamic modelling to achieve realistic results. / 2023-12-02

[pt] Valkó e Oligney propuseram um modelo que estima a evolução da fratura utilizando uma interpretação direta da curva de pressão de fundo medida durante uma operação de fracpack. Os únicos dados de entrada necessários para a aplicação do modelo são os registros geralmente disponíveis durante e após a operação. Considerando uma fratura de geometria radial e utilizando equações simples de fluxo e de geomecânica, o modelo obtém raios de empacotamento a partir da inclinação positiva da curva de pressão de fundo nos períodos de tip screenout. Nesta dissertação o modelo de Valkó e Oligney é aprimorado com a inclusão e o ajuste das equações de estado para o crescimento da fratura e para o processo de filtração, respectivamente. O modelo é também estendido para outras geometrias bidimensionais de fratura, PKN e KGD. A aplicação do modelo foi realizada utilizando os registros de pressão de oito operações de fracpack. Os resultados obtidos são a curva de propagação da fratura, o crescimento da abertura, a eficiência ao longo do tempo e a distribuição final do agente de sustentação na fratura. Para a validação desses resultados foram utilizados dois simuladores comerciais com modelos tridimensionais. Os estudos de caso indicaram que os ajustes realizados aproximaram os resultados do modelo aos obtidos nos simuladores comerciais. Além disso, a aplicação dos modelos desenvolvidos para cada geometria de fratura e a comparação com os resultados dos simuladores comerciais, permitiu confirmar a tendência esperada que, durante uma operação de fracpack, a geometria da fratura se aproxima da radial. / [en] Valkó and Oligney developed a model to estimate fracture evolution using a direct interpretation of the measured bottom hole pressure curve during a fracpack operation. The only input data needed to use the model are the usual records of the job, available during and after the operation. Considering radial fracture geometry and using simplified equations of flow and geomechanics, the model estimates a packing radius of the fracture using the slope of the increasing bottom hole pressure curve during the tip screenout period. In this work, Valkó and Oligney method is enhanced with the inclusion of state equations for the fracture growth and for the leakoff process in order to improve the model, but still maintaining minimum input data. The method is also extended to other two-dimensional fracture geometries, PKN and KGD. To apply the enhanced method, eight fracpack operation data were used. The results obtained are fracture propagation, width growth and fluid efficiency in time as well as the final proppant distribution in the fracture. To validate these results, this work used two commercial simulators with three-dimensional models. The case studies show that the modifications done to Valkó and Oligney method approximate the two-dimensional model results to the ones obtained using the commercial simulators with threedimensional models. Furthermore, the comparison between the application of the model for each fracture geometry and the commercial simulators results confirmed the expected tendency for the fracture geometry during a fracpack operation, which is a radial fracture.

Third sector organisations (TSOs) have been operating in a turbulent environment of social, political and economic changes, presenting challenges to their continued activities. The volunteer workforce, as a key component of TSOs’ human resource, has long been considered crucial for the sector. Despite this acknowledgement, existing research suggests that TSOs have not effectively managed and supported their volunteer workforce in order to sustain development. There are claims for TSOs to place volunteer management (VM) onto a strategic level, and it is considered crucial for TSO managers, CEOs and volunteer coordinators (VCs) to achieve sustainable organisational development through the strategic planning and implementation of VM practices. However, existing research has focussed more on articulating volunteer motives; and little attention has been paid to considering the ways in which individual perspectives influence effective VM. This study addressed the gap by exploring key players’ (CEO, VC and volunteer) perceptions of the policies, practices and processes used to attract, engage and retain volunteers in small to medium Scottish TSOs. It aimed to provide insights into the importance of strategic VM in sustaining TSO performance and in understanding the crucial role of VCs, through unfolding the processes of making and fulfilling individual volunteer psychological contracts (VPCs). Three case studies were carried out within three Scottish TSOs; in-depth qualitative interviews were conducted with participants occupying different roles, CEO (n=3), VC (n=5) and volunteers (n=16). Supplementary data were obtained through documentary study of VM policies and practices. Data collection was guided by a conceptual framework developed by embedding the Resource Based View (RBV) of HRM and HR devolution to the Line into the process of making and fulfilling the psychological contract. Results support the claim that TSOs would benefit from more strategic management of their volunteer workforce as a competitive resource. Examining VM through the lens of the VPC provided empirical evidence to confirm that it is crucial to engage and retain volunteers by shaping their expectations and motives within the TSO, and thus ensure more sustainable TSO performance. The results further support the salient role of VC as volunteer line manager, in attracting, engaging and retaining volunteers through effective VM implementation. In arriving at these results, this research has extended the theoretical debate on the importance of strategic HR management and the key role that line managers can play in achieving this beyond the more dominant private sector focus.