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Heightened awareness of the impact of climate change has led to rapidly increasing penetration of renewable energy resources in electric energy distribution systems. Those distributed energy resources (DERs), mostly inverter-based, can act as resiliency sources for the grid but also introduce new control and stability challenges. In this thesis, a cyber-physical system (CPS) testbed is proposed combining a real-time electro-magnetic transient power system simulation and a practical model for communication network simulation. By regularly updating the CPS testbed with real-world SCADA information, a digital twin is effectively created. The digital twin allows the testing of novel microgrid control and cybersecurity strategies. Simulations using the Virginia Tech Electric Service (VTES) as a test case demonstrate the capability of adequately controlled resources, including solar PV, energy storage, and a synchronous generator, to enhance resilience by providing energy to critical loads. The DERs comply with IEEE disturbance ride-through requirements and switching transients are maintained within acceptable limits. A comprehensive DER-based resiliency plan is developed and validated for the Virginia Tech smart grid. / M.S. / In the last two decades, the increased occurrence of major power outages in the United States underscores the critical need to improve the reliability and resilience of the power grid. Massive investments have been made to install information and communications technology enabling near real-time monitoring and control of the smart grid. Simultaneously, heightened awareness of the impact of climate change led to rapidly increasing penetration of renewable energy resources at the distribution system level. Those distributed energy resources, mostly inverter-based, can act as resiliency sources for the grid but also introduce new control and stability challenges. In this work, a comprehensive testbed is proposed for the real-time simulation of both the power systems and communication networks. This method allows the testing of novel microgrid control and cybersecurity strategies. The testbed is used to develop and validate a resiliency plan for the Virginia Tech Electric Service using distributed energy resources.

Ma Ning. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 49-57). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.5 / Chapter 2 --- Literature Review --- p.11 / Chapter 2.1 --- Problems about Using Sibling Samples --- p.19 / Chapter 2.2 --- Difficulties with the Within-twin-pair Studies --- p.20 / Chapter 3 --- Method --- p.21 / Chapter 3.1 --- Omitted Variable Bias (Selection Effect) --- p.21 / Chapter 3.1.1 --- OLS Model --- p.21 / Chapter 3.1.2 --- Fixed-Effect Model --- p.23 / Chapter 3.1.3 --- GLS Model --- p.23 / Chapter 3.2 --- Measurement Error --- p.24 / Chapter 4 --- Data --- p.26 / Chapter 5 --- Results --- p.29 / Chapter 5.1 --- "OLS, Fixed-Effect, GLS and IV estimates" --- p.29 / Chapter 5.2 --- Important findings --- p.34 / Chapter 5.3 --- Further Results --- p.35 / Chapter 5.3.1 --- Consistency of Fixed-Effect Estimate --- p.35 / Chapter 5.3.2 --- Smoking as an Instrument for Education --- p.39 / Chapter 5.3.3 --- Symmetry Test --- p.41 / Chapter 5.3.4 --- Hausman Test --- p.44 / Chapter 5.3.5 --- Selection Bias --- p.45 / Chapter 6 --- Conclusions --- p.48 / Chapter 7 --- Bibliography --- p.49

Thesis (M.A.)--Carleton University, 2004. / Includes bibliographical references (p. 111-118). Also available in electronic format on the Internet.

Hexagonal close packed (hcp) crystal structures, such as magnesium and titanium, provide formidable strength in relation to density. Current interests in reducing CO2 emissions, hold magnesium as a contender to lightweight passenger vehicles. Although significant decreases in mass could be achieved through magnesium, poor formability and energy absorption capacity limit the possibility for cost-effective production. This Master’s thesis aims to observe the microstructure and micro texture evolution induced by twinning using interrupted electron backscattered diffraction (EBSD) characterization in order to determine potential mechanisms causing early failure of magnesium alloys. This study revealed {10-11} contraction twins at stress levels contrary to the basic hypothesis of the Schmid effect revealing the importance of non-Schmid effects in damage. Furthermore, it was observed that crack nucleation occurs in magnesium alloys, due mainly to interaction between twins and microstructure defects and form inside contraction twins, causing cleavage-like terraces in the fracture surface.

Introdução: Embora o nascimento de gêmeos tenha sempre chamado atenção, não há fatores genéticos ou ambientais conhecidos que podem determinar o nascimento de monozigóticos gêmeos (MZ). E mesmo para gêmeos dizigóticos (DZ), influências genéticas não são completamente compreendidas. Objetivos: Um estudo prévio do nosso grupo demonstrou que o alelo C do polimorfismo rs1042522 no gene TP53 foi mais frequente nas mães de gêmeos do que nas mães de gestação única em uma pequena cidade no sul do Brasil. A fim de esclarecer se este foi um fator isolado, foi realizado um estudo observacional de caso-controle de base populacional. Métodos: As amostras foram selecionadas a partir de um programa de investigação de paternidade financiado pelo estado do Rio grande do Sul. As amostras foram consideradas casos em que duas das crianças tinham a mesma data de nascimento e os controles eram de amostras em que pelo menos dois filhos nasceram em datas diferentes. O método de escolha dos controles foi sequencial, sendo utilizados os primeiros que preenchessem esta condição a cada ano. Resultados: De 2007 a 2013, foram 32.661 registros pesquisados e 283 (0,9%) gêmeos foram encontrados (119 MZ e 164 DZ). Frequências alélicas e genotípicas não foram diferentes entre as mães de gêmeos ou mães de não gêmeos. No entanto, as mães de gêmeos MZ apresentaram uma maior frequência do genótipo GG e menor frequência do alelo C quando comparado com as mães de gêmeos DZ. Além disso, a proporção de gêmeos monozigóticos (42%) é maior do que normalmente relatado (30%). Finalmente, a proporção de gêmeos encontrados neste estudo parece ser mais realista, já que esta amostra não é supostamente de usuárias de técnicas de reprodução assistida. / Introduction: Although the birth of twins has always attracted attention, there are no known genetic or environmental factors that can determine the birth of monozygotic (MZ) twins. And even for dizygotic (DZ) twins, genetic influences are not completely understood. Objective: A previous study from our group has shown that the C allele of polymorphism rs1042522 in TP53 gene was more frequent in the mothers of twins than in the mothers of singletons in a small village in South Brazil. In order to clarify if this was an isolated factor, we performed a population-based observational case-control study. Methods: Samples were selected from a state-funded program of paternity investigation. Samples were considered cases when two of the children had the same date of birth whereas controls were those samples in which at least two children were born in different dates. The first subsequent sample fulfilling control criteria was included after each case. Results: From 2007 to 2013, 32,661 records were searched and 283 (0.9%) twins were found (119 MZ and 164 DZ). Genotypic and allele frequencies were not different between mothers of twins or mothers of singletons. However, mothers of MZ twins showed a higher frequency of GG genotype and lower frequency of the C allele when compared to mothers of DZ twins. Also, the proportion of MZ twins (42%) is higher than usually reported (30%). Finally, the proportion of twins found in this study seems to be more realistic, as this sample is allegedly not user of assisted reproduction techniques.

Na literatura psicológica, encontramos pesquisas realizadas com gêmeos visando estudar a influência de fatores genéticos versus ambientais na estruturação da personalidade e também no campo da psicopatologia. Entretanto, existem poucos relatos de pesquisas voltados para a interação intra-par de gêmeos e entre os gêmeos e seus cuidadores, especialmente em relação às questões edípicas. O fenômeno, tão estudado pela psicanálise, tem sido pouco investigado na vivência de situações triangulares entre os co-gêmeos e seus pais. O método de Observação Psicanalítica modelo Esther Bick inspirou o planejamento desta tese, que tem como objetivos: observar e descrever as relações objetais triangulares entre os gêmeos e seus pais durante o primeiro ano de vida; analisar a possibilidade de a triangulação edípica ocorrer prioritariamente entre o par de gêmeos; verificar se a \"presença real\" do co-gêmeo poderia exacerbar a vivência como \"terceiro excluído\" entre os gêmeos. Participaram cinco pares de gêmeos recém-nascidos e suas respectivas famílias, sendo dois pares masculinos(monozigoto e dizigoto), dois pares femininos (monozigoto e dizigoto) e um par de sexos diferentes. Foram realizadas visitas semanais com duração de uma hora cada, às residências dos gêmeos, durante o primeiro ano de vida, a fim de observar os gêmeos e seus cuidadores. A observadora pode presenciar o que se passava na relação intra-par de gêmeos, bem como entre os gêmeos e demais pessoas presentes. Após cada sessão de observação foi elaborado um relatório constando os comportamentos observados e as percepções da observadora em relação aos fatos. Foram estudados especialmente os seguintes fenômenos observados nas famílias de gêmeos: atendimento individual mãe-gêmeos; atendimento conjunto mãe-gêmeos; disputa de colo/atenção materna; atendimento pai-gêmeos; relacionamento intra-par de gêmeos. As relações triangulares envolvendo os co-gêmeos e seus pais foram analisadas, tendo como subsídio as teorias de Freud e Klein a respeito das questões edípicas. Foram percebidas quatro formas de relação triangular além do triângulo edípico filho-mãe-pai nas famílias estudadas. / In the psychological literature, we have found researches performed with twins where the aim was to study the influence of genetic factors versus environmental ones in the structuring of the personality and also in the field of the psychology. However, there are few reports of researches related to the twins\' intra-pair interaction and between the twins and their caretakers, especially in relation to the oedipal issues. The phenomenon, so studied by the psychoanalysis, has been little investigated in the experience of triangular situations between the co-twins and their parents. Esther Bick method of Psychoanalytic Observation model inspired the planning of this thesis, which has as its objectives: to observe and to describe the oppose triangular relationships between the twins and their parents during the first year of life; to analyze the possibility that the oedipal triangulation may happen essentially between the pair of twins; to verify if the \"real presence\" of the co-twin could exacerbate the existence as a \"third excluded\" between the twins. Five pairs of just born twins and their respective families participated in the study; among them we have two male pairs (monozygotic and dizygotic twins), two female pairs (monozygotic and dizygotic twins) and a pair of different sexes. Weekly visits were carried out with an hour duration each, to the twins\' residences, during the first year of life, in order to observe the twins and their caretakers. The observer could witness what happened in the twins\' intra-pair relationship, as well as between the twins and among the other people present. After each observation session a report was elaborated including the observed behaviors and the observer\'s perceptions related to the facts. The following observed phenomena were specially studied in the twins\' families: individual attendance mother-twin; pair attendance mother-twins; dispute of mother\'s holding/attention; father-twins attendance; twins\' intra-pair relationship. The triangular relationships involving the co-twins and their parents were analyzed, having as its subsidy Freud\'s and Klein\'s theories regarding to oedipal relations. It has been noticed four triangular relationship forms besides the triangle son-mother-father oedipal one in the studied families.

Mothers' and fathers' perceptions of the quality of coparenting – the way in which they work together in their role as parents – forms the focus of three papers that comprise this thesis. Using a novel sample of ‘intact' families with young twins, this research extends the existing coparenting literature beyond its typical focus on first-born children, to include more complex families. Participants were families who were part of the Twins, Family and Behaviour (TFaB) Study, a longitudinal, multimethod study of UK families with twins born in 2009/10 conducted by myself and my colleague over a two-year period. Paper 1 examines bidirectional associations between coparenting and the marital relationship during the transition-to-school period. Controlling for cross-sectional associations and temporal stability, parents' perceptions of higher quality coparenting were associated with their subsequent report of a higher quality marital relationship. Reciprocal associations between the marital relationship and subsequent coparenting, however, were not evidenced. These findings highlight the salience of coparenting for the marital relationship, and suggest that interventions seeking to improve the couples' marital relationship should pay close attention to their coparenting. Paper 2 focuses on parenting sense of competence (PSOC), examining the role of children's disruptive behaviour, coparenting, and their interaction. For both mothers and fathers there was a significant interaction between their perceptions of coparenting and children's disruptive behaviour such that high quality coparenting may protect the PSOC of parents dealing with high levels of children's disruptive behaviour. These findings imply that practitioners and interventions concerned with promoting PSOC should pay due attention to the quality of coparenting as an important family context. Paper 3 examines family-wide and child-specific effects of coparenting and coercive parenting on the development of children's disruptive behaviour. Mothers' perceptions of coparenting interacted with maternal overall coercive parenting such that high quality coparenting intensified the toxicity of maternal coercive parenting for children's disruptive behaviour. This novel – and unexpected – finding indicates that the influence of high quality coparenting is not necessarily always positive. Coparenting interventions aiming to improve child outcomes would therefore be well-advised to also consider parenting strategies. Further research is encouraged to explore these research questions within samples of socioeconomic diversity and across family types, as well as studies designed to examine twin and non-twin family differences.

There have been numerous twin-based studies in the past that control for the unobservable variables in the analyses. However, these past studies have often yielded contradictory results with no consensus on some important issues and no definite conclusions. The objective of the present study is an attempt to explain some of the differences in the past studies, and to re-examine some issues on returns to education, the importance of genetic and environmental factors, and the significance of measurement errors. / This study applies four twin-based models to three available US twin data. The empirical results in this study show that (1) while some differences in existing studies are caused by different data used, other differences are due to different models used; (2) the "true" returns to schooling are mostly less than the "overall" returns to schooling, indicating a positive omitted variable bias; (3) the omitted variables are a significant portion, viz. approximately 40%, of the "overall" returns to schooling; (4) these omitted variables, when divided into the genetic and environmental factors, generally indicate that environmental factors have a stronger effect than genetic factors; (5) models with two schooling variables are more prone to measurement error, biasing the estimates more significantly; (6) the measurement error problem in the schooling variable biases the estimates and the magnitude of the bias depends on the data used; and (7) results for males and females are different. / Yung Chor-Wing Linda. / "May 2000." / Adviser: Junsen Zhang. / Source: Dissertation Abstracts International, Volume: 61-08, Section: A, page: 3293. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. 202-205). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest dissertations and theses, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.