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Wind power is a fast-growing, sustainable energy source. However, the problem of wind variability as it relates to wind power reliability is an obstacle to its large-scale deployment. It is possible to improve the reliability of wind power by interconnecting wind generation. In this study, wind power plants within the Midwest ISO were aggregated to examine the effect on reliability. Wind speed data from the North American Regional Reanalysis were used to calculate wind power data. It was found that the reliability of interconnected wind power was improved relative to individual wind power plants in both the short-term and the long-term, and that the most significant improvements were at the highest scales of interconnection. It was also found that the reliability of interconnected wind power is more directly related to the area of the network rather than the number of wind power plants in the network.

Esta dissertação apresenta a importância do gerenciamento da confiabilidade de um produto durante seu desenvolvimento. Tal gerenciamento consiste em um processo sistemático que resulta no alcance dos requisitos governamentais, do cliente e da empresa. Estudou-se a metodologia de gerenciamento da confiabilidade através do planejamento da confiabilidade meta, alocação ótima de confiabilidade, avaliação e modelagem da confiabilidade, planejamento do crescimento da confiabilidade, controle do crescimento da confiabilidade até a obtenção dos resultados planejados. Através dessa metodologia, em um estudo aplicado contemplando um produto médico-hospitalar, foi possível: (a) identificar os componentes críticos do produto, (b) identificar a lacuna existente entre o valor de confiabilidade no início do projeto quando comparado à meta, (c) planejar o crescimento da confiabilidade ao longo das fases do projeto, (d) realizar melhorias ou reprojetos nos componentes do produto, (e) controlar o crescimento da confiabilidade e (f) alcançar a confiabilidade planejada. Os resultados obtidos foram de um aumento de 24% para 100% na confiabilidade do produto para cinco anos de utilização e de 0% para 83% para dez anos de utilização. Os valores obtidos de confiabilidade superaram os valores planejados, confirmando a eficiência da metodologia adotada. / This study discusses the relevance of Product Reliability Management during the product development phase. It consists of a systematic process that results in achieving the requirements of government regulations, customer satisfaction and companies goals. We studied the Product Reliability Management methodology through five aspects, including: target planning, optimal allocation, evaluation and modeling of product reliability, growth planning, and growth control to achieve the planned results. Using this methodology, applied in a study comprising the analysis of a medical product, it was possible to: (a) identify the critical components of the product (b) identify the gap between the reliability rate at the beginning of the project when compared to the final target (c) plan the growth of reliability throughout the phases of the project (d) make improvements or redesign product components (e) control the growth of reliability and (f) achieve the planned product reliability. The obtained results show an increase of 24% to 100% on five years product reliability, and from 0% to 83% for ten years product reliability. The values of reliability exceeded the planned values, confirming the effectiveness of the Product Reliability Management methodology.

abstract: Several decades of transistor technology scaling has brought the threat of soft errors to modern embedded processors. Several techniques have been proposed to protect these systems from soft errors. However, their effectiveness in protecting the computation cannot be ascertained without accurate and quantitative estimation of system reliability. Vulnerability -- a metric that defines the probability of system-failure (reliability) through analytical models -- is the most effective mechanism for our current estimation and early design space exploration needs. Previous vulnerability estimation tools are based around the Sim-Alpha simulator which has been to shown to have several limitations. In this thesis, I present gemV: an accurate and comprehensive vulnerability estimation tool based on gem5. Gem5 is a popular cycle-accurate micro-architectural simulator that can model several different processor models in close to real hardware form. GemV can be used for fast and early design space exploration and also evaluate the protection afforded by commodity processors. gemV is comprehensive, since it models almost all sequential components of the processor. gemV is accurate because of fine-grain vulnerability tracking, accurate vulnerability modeling of squashed instructions, and accurate vulnerability modeling of shared data structures in gem5. gemV has been thoroughly validated against extensive fault injection experiments and achieves a 97\% accuracy with 95\% confidence. A micro-architect can use gemV to discover micro-architectural variants of a processor that minimize vulnerability for allowed performance penalty. A software developer can use gemV to explore the performance-vulnerability trade-off by choosing different algorithms and compiler optimizations, while the system designer can use gemV to explore the performance-vulnerability trade-offs of choosing different Insruction Set Architectures (ISA). / Dissertation/Thesis / Masters Thesis Computer Science 2016

abstract: Potential-Induced Degradation (PID) is an extremely serious photovoltaic (PV) durability issue significantly observed in crystalline silicon PV modules due to its rapid power degradation, particularly when compared to other PV degradation modes. The focus of this dissertation is to understand PID mechanisms and to develop PID-free cells and modules. PID-affected modules have been claimed to be fully recovered by high temperature and reverse potential treatments. However, the results obtained in this work indicate that the near-full recovery of efficiency can be achieved only at high irradiance conditions, but the full recovery of efficiency at low irradiance levels, of shunt resistance, and of quantum efficiency (QE) at short wavelengths could not be achieved. The QE loss observed at short wavelengths was modeled by changing the front surface recombination velocity. The QE scaling error due to a measurement on a PID shunted cell was addressed by developing a very low input impedance accessory applicable to an existing QE system. The impacts of silicon nitride (SiNx) anti-reflection coating (ARC) refractive index (RI) and emitter sheet resistance on PID are presented. Low RI ARC cells (1.87) were observed to be PID-susceptible whereas high RI ARC cells (2.05) were determined to be PID-resistant using a method employing high dose corona charging followed by time-resolved measurement of surface voltage. It has been demonstrated that the PID could be prevented by deploying an emitter having a low sheet resistance (~ 60 /sq) even if a PID-susceptible ARC is used in a cell. Secondary ion mass spectroscopy (SIMS) results suggest that a high phosphorous emitter layer hinders sodium transport, which is responsible for the PID. Cells can be screened for PID susceptibility by illuminated lock-in thermography (ILIT) during the cell fabrication process, and the sample structure for this can advantageously be simplified as long as the sample has the SiNx ARC and an aluminum back surface field. Finally, this dissertation presents a prospective method for eliminating or minimizing the PID issue either in the factory during manufacturing or in the field after system installation. The method uses commercially available, thin, and flexible Corning® Willow® Glass sheets or strips on the PV module glass superstrates, disrupting the current leakage path from the cells to the grounded frame. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2016

Esta dissertação apresenta a importância do gerenciamento da confiabilidade de um produto durante seu desenvolvimento. Tal gerenciamento consiste em um processo sistemático que resulta no alcance dos requisitos governamentais, do cliente e da empresa. Estudou-se a metodologia de gerenciamento da confiabilidade através do planejamento da confiabilidade meta, alocação ótima de confiabilidade, avaliação e modelagem da confiabilidade, planejamento do crescimento da confiabilidade, controle do crescimento da confiabilidade até a obtenção dos resultados planejados. Através dessa metodologia, em um estudo aplicado contemplando um produto médico-hospitalar, foi possível: (a) identificar os componentes críticos do produto, (b) identificar a lacuna existente entre o valor de confiabilidade no início do projeto quando comparado à meta, (c) planejar o crescimento da confiabilidade ao longo das fases do projeto, (d) realizar melhorias ou reprojetos nos componentes do produto, (e) controlar o crescimento da confiabilidade e (f) alcançar a confiabilidade planejada. Os resultados obtidos foram de um aumento de 24% para 100% na confiabilidade do produto para cinco anos de utilização e de 0% para 83% para dez anos de utilização. Os valores obtidos de confiabilidade superaram os valores planejados, confirmando a eficiência da metodologia adotada. / This study discusses the relevance of Product Reliability Management during the product development phase. It consists of a systematic process that results in achieving the requirements of government regulations, customer satisfaction and companies goals. We studied the Product Reliability Management methodology through five aspects, including: target planning, optimal allocation, evaluation and modeling of product reliability, growth planning, and growth control to achieve the planned results. Using this methodology, applied in a study comprising the analysis of a medical product, it was possible to: (a) identify the critical components of the product (b) identify the gap between the reliability rate at the beginning of the project when compared to the final target (c) plan the growth of reliability throughout the phases of the project (d) make improvements or redesign product components (e) control the growth of reliability and (f) achieve the planned product reliability. The obtained results show an increase of 24% to 100% on five years product reliability, and from 0% to 83% for ten years product reliability. The values of reliability exceeded the planned values, confirming the effectiveness of the Product Reliability Management methodology.

abstract: ABSTRACT As the use of photovoltaic (PV) modules in large power plants continues to increase globally, more studies on degradation, reliability, failure modes, and mechanisms of field aged modules are needed to predict module life expectancy based on accelerated lifetime testing of PV modules. In this work, a 26+ year old PV power plant in Phoenix, Arizona has been evaluated for performance, reliability, and durability. The PV power plant, called Solar One, is owned and operated by John F. Long's homeowners association. It is a 200 kWdc, standard test conditions (STC) rated power plant comprised of 4000 PV modules or frameless laminates, in 100 panel groups (rated at 175 kWac). The power plant is made of two center-tapped bipolar arrays, the north array and the south array. Due to a limited time frame to execute this large project, this work was performed by two masters students (Jonathan Belmont and Kolapo Olakonu) and the test results are presented in two masters theses. This thesis presents the results obtained on the south array and the other thesis presents the results obtained on the north array. Each of these two arrays is made of four sub arrays, the east sub arrays (positive and negative polarities) and the west sub arrays (positive and negative polarities), making up eight sub arrays. The evaluation and analyses of the power plant included in this thesis consists of: visual inspection, electrical performance measurements, and infrared thermography. A possible presence of potential induced degradation (PID) due to potential difference between ground and strings was also investigated. Some installation practices were also studied and found to contribute to the power loss observed in this investigation. The power output measured in 2011 for all eight sub arrays at STC is approximately 76 kWdc and represents a power loss of 62% (from 200 kW to 76 kW) over 26+ years. The 2011 measured power output for the four south sub arrays at STC is 39 kWdc and represents a power loss of 61% (from 100 kW to 39 kW) over 26+ years. Encapsulation browning and non-cell interconnect ribbon breakages were determined to be the primary causes for the power loss. / Dissertation/Thesis / M.S.Tech Technology 2012

abstract: Non-volatile memories (NVM) are widely used in modern electronic devices due to their non-volatility, low static power consumption and high storage density. While Flash memories are the dominant NVM technology, resistive memories such as phase change access memory (PRAM) and spin torque transfer random access memory (STT-MRAM) are gaining ground. All these technologies suffer from reliability degradation due to process variations, structural limits and material property shift. To address the reliability concerns of these NVM technologies, multi-level low cost solutions are proposed for each of them. My approach consists of first building a comprehensive error model. Next the error characteristics are exploited to develop low cost multi-level strategies to compensate for the errors. For instance, for NAND Flash memory, I first characterize errors due to threshold voltage variations as a function of the number of program/erase cycles. Next a flexible product code is designed to migrate to a stronger ECC scheme as program/erase cycles increases. An adaptive data refresh scheme is also proposed to improve memory reliability with low energy cost for applications with different data update frequencies. For PRAM, soft errors and hard errors models are built based on shifts in the resistance distributions. Next I developed a multi-level error control approach involving bit interleaving and subblock flipping at the architecture level, threshold resistance tuning at the circuit level and programming current profile tuning at the device level. This approach helped reduce the error rate significantly so that it was now sufficient to use a low cost ECC scheme to satisfy the memory reliability constraint. I also studied the reliability of a PRAM+DRAM hybrid memory system and analyzed the tradeoffs between memory performance, programming energy and lifetime. For STT-MRAM, I first developed an error model based on process variations. I developed a multi-level approach to reduce the error rates that consisted of increasing the W/L ratio of the access transistor, increasing the voltage difference across the memory cell and adjusting the current profile during write operation. This approach enabled use of a low cost BCH based ECC scheme to achieve very low block failure rates. / Dissertation/Thesis / Ph.D. Electrical Engineering 2014

Orientador: Maria Beatriz Duarte Gavião / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-10T12:37:49Z (GMT). No. of bitstreams: 1 Barbosa_TaisdeSouza_M.pdf: 1685317 bytes, checksum: 7aaeb0f9822b99fbb6aec351a46ce7e5 (MD5) Previous issue date: 2008 / Resumo: Atualmente, o interesse pela qualidade de vida e saúde bucal em crianças vem aumentando, já que as desordens orais provavelmente apresentam efeito negativo na qualidade de vida das mesmas. Um tema que vem recebendo grande destaque é a comparação entre os relatos de qualidade de vida relacionada à saúde bucal originários das crianças e dos pais. Assim, três revisões sistemáticas foram desenvolvidas neste trabalho com o objetivo de revisar a literatura em informações válidas e consistentes provenientes das crianças e pais considerando a qualidade de vida relacionada à saúde bucal em crianças, e identificar o padrão de concordância/discordância entre ambos. O levantamento bibliográfico, de 1985 a 2007, foi feito nas bases de dados Medline, ISI, Lilacs e Scielo. Dois pesquisadores realizaram a busca individualmente e selecionaram os artigos que utilizaram instrumentos validados, com medidas quantitativas de saúde bucal da criança e direcionados às percepções das crianças e dos pais sobre qualidade de vida relacionada à saúde bucal em crianças. Na primeira revisão foram encontrados 89 artigos e selecionados treze, os quais demonstraram validade construtiva adequada. Entretanto, o autoentendimento da criança em relação à saúde bucal e ao bem-estar foi afetado pelas variáveis: idade, gênero, raça, educação, cultura, experiências relacionadas às condições bucais e à idade, oportunidade de tratamento, estágio de desenvolvimento, adaptação cultural dos questionários e auto-percepção da necessidade de tratamento. Doze artigos de 402 inicialmente identificados foram incluídos na segunda revisão. Os resultados demonstraram que as relações entre qualidade de vida e saúde bucal em crianças não são diretas, mas mediadas por variáveis pessoais, sociais e ambientais, assim como pelo desenvolvimento da criança, o qual influencia a compreensão da relação entre saúde, doença e qualidade de vida. Na terceira revisão, dos 87 artigos que foram criticamente avaliados, cinco estudos foram selecionados, os quais demonstraram que as crianças e os pais não apresentam necessariamente as mesmas percepções sobre a qualidade de vida relacionada à saúde bucal. Embora o relato dos pais seja incompleto, devido ao desconhecimento sobre algumas experiências da criança, informações úteis podem ser obtidas. Estas revisões sistemáticas foram relevantes não somente para identificar, revisar e avaliar os estudos prévios sobre a qualidade de vida relacionada à saúde bucal em crianças, mas principalmente para o início de uma série de pesquisas nas populações de crianças e pais brasileiros neste contexto. Sendo assim, dois estudos transversais foram realizados. No primeiro estudo realizou-se a tradução dos questionários Child Perceptions Questionnaires (CPQ8-10 e CPQ11-14) para língua portuguesa, as respectivas adaptações culturais (n=80) e a verificação da validade (n=210) e confiabilidade (n=40). Os resultados demonstraram que ambos os questionários são válidos e confiáveis para uso na população de crianças brasileiras, embora a validade discriminativa tenha sido esporádica, inconsistente ou inexistente. O segundo estudo consistiu da tradução do questionário Parental Perceptions Questionnaire (PPQ) para a língua portuguesa e as adaptações culturais necessárias (n=20), além da avaliação da respectiva validade (n=210), confiabilidade (n=20) e concordância entre os relatos da criança e dos pais (210 pares de crianças e pais) sobre a qualidade de vida relacionada à saúde bucal das crianças. Os resultados demonstraram que a versão brasileira do PPQ apresentou propriedades psicométricas adequadas. Alguns pais apresentaram conhecimento limitado sobre a qualidade de vida relacionada à saúde bucal das crianças. Considerando que as percepções dos pais e das crianças mensuram percepções diferentes da mesma realidade, informações provenientes desses podem ser complementos na avaliação da criança / Abstract: More recently, there has been increasing interest in the oral health-related quality of life (OHRQoL) of children, since pediatric oral disorders are likely to have a negative effect on the child quality of life (QoL). One issue that receives a great deal of attention is the comparison of the measurement of children OHRQoL reports with those of their parents. In this way, three systematic reviews were carried out to review the literature on valid and reliable informations from children and parents concerning child OHRQoL, and to identify the pattern of agreement/disagreement between their reports. The literature was searched using Medline, ISI, Lilacs and Scielo, from 1985-2007. Two researchers independently checked and then selected only articles that used well-validated instruments, provided quantitative measurements of child clinical oral health status, and presented children and parental perceptions of child OHRQoL. In the first systematic review, from 89 records found, thirteen fulfilled the criteria. All selected studies suggested good construct validity. However, child understanding of oral health and well-being are affected by age, age-related experiences, gender, race, education, culture, experiences related to oral conditions, opportunities for treatment, childhood period of changes, back-translating questionnaire and child self-perceived treatment need. Twelve of 402 articles originally identified were included in the second systematic review. The results showed that the relationships between clinical oral health status and QoL in children were not direct, but mediated by a variety of personal, social and environmental variables, as well as by the child development, which have influence on the comprehension about the relationship among health, illness and QoL. In the third one, out of 87 articles that were critically assessed, five studies were selected, which showed that children and parents do not necessarily share similar views about child OHRQoL. Although the parental reports may be incomplete due to lack of knowledge about certain experiences, they still provide useful information. These systematic reviews were important not only to identify, to review and to assess the literature findings on child OHRQoL, but principally to start a series of researches on Brazilian child and parent populations concerning child OHRQoL. In this way, two cross-sectional studies were conducted. The first one translated the Child Perceptions Questionnaires (CPQ8-10 and CPQ11-14) into Portuguese language, made the necessary cultural adaptations (n=80) and evaluated their validity (n=210) and reliability (n=40). The results showed that both questionnaires were valid and reliable for use in Brazilian child population, although discriminant validity had been sporadic, inconsistent or non-existent. The second study translated the Parental Perceptions Questionnaire (PPQ) into Portuguese, made the necessary cultural adaptations (n=20), tested its validity (n=210) and reliability (n=20) and evaluated the concordance between parent and child reports (210 pairs of parents and children) concerning child OHRQoL. The results showed that the Portuguese version of PPQ had good psychometric properties. Some parents have limited knowledge about child¿ OHRQoL. Given that parental and child reports are measuring different perceptions of the same reality, information provided by parents can complement the child¿ evaluation / Mestrado / Odontopediatria / Mestre em Odontologia

Orientadores: Paulo Roberto Gardel Kurka, Kamal A. R. Ismail / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-28T16:10:56Z (GMT). No. of bitstreams: 1 AraujoFilho_BeneditoSade_D.pdf: 5884845 bytes, checksum: 9d32465225c3d77bcef03cb8d144fad0 (MD5) Previous issue date: 1999 / Resumo: O objetivo desta pesquisa é elaborar técnicas e critérios para a projeção de desvios de calibração e estudo de confiabilidade nas medidas de termopares. Propõe-se a criação de um modelo baseado no estudo dos desvios das curvas de calibração. A distribuição qui-quadrado é utilizada na determinação dos limites das curvas de desvio em função de tempo para diversos tipos de termopares em cada temperatura específica. O modelo exponencial é escolhido para a função de distribuição de confiabilidade. Os parâmetros de desvio são determinados a partir de um procedimento que tem por base a análise de dados experimentais. Resultados de aplicação prática da metodologia proposta são apresentados para o cálculo das curvas de confiabilidade de termopares do tipo T e J. São apresentadas sugestões sobre a extensão de uso e aperfeiçoamento das técnicas desenvolvidas / Abstract: The purpose of the present work is to develop techniques and suitable criteria to be used in the prediction of calibration curve deviations and reliability of thermocouple measurements. The chi-squared distribuition is used to determine the limits of time deviation curves of different thermocouple types, at specific temperatures. The exponential model is chosen to represent the reliability distribution function. Deviation parameters are determined from a procedure based on experimental data analysis. Results of the practical application of the proposed methodology are shown for the determination of reliability curves of thermocouples of the type T and J. Improvement of the techniques as well as extention of their applications are suggested at the end of the work / Doutorado / Projetos Mecanicos / Doutor em Engenharia Mecânica