Preliminary temperature Accelerated Life Test (ALT) on III-V commercial concentrator triple-junction solar cells

A quantitative temperature accelerated life test on sixty GaInP/GaInAs/Ge triple-junction commercial concentrator solar cells is being carried out. The final objective of this experiment is to evaluate the reliability, warranty period, and failure mechanism of high concentration solar cells in a moderate period of time. The acceleration of the degradation is realized by subjecting the solar cells at temperatures markedly higher than the nominal working temperature under a concentrator Three experiments at three different temperatures are necessary in order to obtain the acceleration factor which relates the time at the stress level with the time at nominal working conditions. . However, up to now only the test at the highest temperature has finished. Therefore, we can not provide complete reliability information but we have analyzed the life data and the failure mode of the solar cells inside the climatic chamber at the highest temperature. The failures have been all of them catastrophic. In fact, the solar cells have turned into short circuits. We have fitted the failure distribution to a two parameters Weibull function. The failures are wear-out type. We have observed that the busbar and the surrounding fingers are completely deteriorate

Instrumentación de referencia para realización automática de ensayos de fiabilidad

En todo proceso de desarrollo de un dispositivo electrónico o equipo cabe la necesidad de evaluar la fiabilidad de sus componentes, es decir, cual es el porcentaje de equipos que tras un determinado periodo de vida mantiene todas sus funcionalidades dentro de especificaciones. La evaluación de la fiabilidad mediante ensayos acelerados es la herramienta que permite una estimación de la vida del dispositivo o equipo de forma previa a su comercialización. La cuantificación de la fiabilidad es crítica para identificar los costos de un determinado periodo de garantía, y para ofrecer a los clientes el nivel de calidad deseado. El objetivo de este Proyecto Fin de Carrera, es el diseño de un sistema automático de instrumentación versátil, para la realización y caracterización de ensayos acelerados, el cual nos sirva para abordar una amplia gama de ensayos con los que evaluar la fiabilidad de los dispositivos electrónicos o equipos. Además del uso industrial donde se evaluará la fiabilidad de forma previa a la comercialización, este sistema se podrá emplear en la docencia de esta área, y fundamentalmente para la realización de ensayos acelerados en investigación de dispositivos electrónicos. La versatilidad de nuestro hardware y aplicación software es un punto a favor, ya que con este sistema de instrumentación se pueden realizar numerosos tipos de ensayos acelerados, sin el problema de tener que cambiar toda la instrumentación, cada vez que se quiera realizar otro ensayo distinto. Los componentes que se elijan para realizar el ensayo acelerado, serán sometidos a un estrés (tensión, corriente, humedad, temperatura…) y se podrá ir observando cómo envejecen, lo que nos permite evaluar la vida del dispositivo en un corto periodo, emulando sus condiciones de trabajo, además de estudiar la fiabilidad también se puede identificar como se degradan sus características principales antes del fallo. El Software utilizado en este Proyecto se ha implementado con un lenguaje de programación gráfico para instrumentación, LabVIEW. La aplicación software se explica de manera muy detallada a lo largo de la memoria, para que su uso y adaptación si fuese necesario no suponga ningún problema para el usuario. En la última parte de esta memoria se encuentra la guía de usuario y un ensayo acelerado planteado como ejemplo. Explicaremos como se han interconectado los equipos a los componentes en los que se va a realizar el ensayo y así se comprobará el correcto funcionamiento del software tomando las medidas necesarias. ABTRACT In all process of development of an electronic device or equipment, we have the need to evaluate the reliability of its components, that is to say, what percentage of equipment that after a certain period of life keeps all of its functionalities within specifications. The evaluation of reliability by means of accelerated tests is the tool that allows an estimation of the lifetime of the device or equipment prior to its marketing. The quantification of reliability is critical to identify the costs of a specific warranty period, and to offer customers the desired quality level. The objective of this Thesis is the design of an automatic very versatile instrument for the realization and characterization of accelerated tests, which will help us to address a wide range of tests to assess the reliability of the devices or electronic equipment. In addition to industrial use where test the reliability before its commercialization, use it can be used in teaching of this area, fundamentally for the realization of accelerated testing in the investigation of electronic devices. The versatility of our hardware and software implementation is a plus, given that this instrumentation system can perform numerous types of accelerated tests, without the problem to have to change everything, every time you want to make another different test. The components that will be chosen to perform the accelerated test, will be subjected to stress (voltage, current, humidity, temperature ...) and you can observe how they age, allowing us to evaluate the life of the device in a short period, emulating their working conditions. In addition to studying the reliability it can also identify how its main characteristics are degraded before failure. The software used in this Thesis has been implemented with a graphical programming language for instrumentation, LabVIEW. This software is explained in great detail throughout the Thesis, so that its use and adaptation, if necessary, will not be a problem for the user. In the last part of this memory we will expose a user guide and test that we have done. We will explain how the equipment has been interconnected to the components in which we are going to perform the test and so we will check the correct operation of the software taking the necessary measures.

Evaluation of the reliability of commercial concentrator triple-junction solar cells by means of accelerated life tests (ALT)

A temperature accelerated life test on commercial concentrator lattice-matched GaInP/GaInAs/Ge triple-junction solar cells has been carried out. The solar cells have been tested at three different temperatures: 119, 126 and 164 °C and the nominal photo-current condition (820 X) has been emulated by injecting current in darkness. All the solar cells have presented catastrophic failures. The failure distributions at the three tested temperatures have been fitted to an Arrhenius-Weibull model. An Arrhenius activation energy of 1.58 eV was determined from the fit. The main reliability functions and parameters (reliability function, instantaneous failure rate, mean time to failure, warranty time) of these solar cells at the nominal working temperature (80 °C) have been obtained. The warranty time obtained for a failure population of 5 % has been 69 years. Thus, a long-term warranty could be offered for these particular solar cells working at 820 X, 8 hours per day at 80 °C.

Evaluation of the reliability of high concentrator GaAs solar cells by means of temperature accelerated aging tests

ABSTRACT Evaluating the reliability, warranty period, and power degradation of high concentration solar cells is crucial to introducing this new technology to the market. The reliability of high concentration GaAs solar cells, as measured in temperature accelerated life tests, is described in this paper. GaAs cells were tested under high thermal accelerated conditions that emulated operation under 700 or 1050 suns over a period exceeding 10 000 h. Progressive power degradation was observed, although no catastrophic failures occurred. An Arrhenius activation energy of 1.02 eV was determined from these tests. The solar cell reliability [R(t)] under working conditions of 65°C was evaluated for different failure limits (1–10% power loss). From this reliability function, the mean time to failure and the warranty time were evaluated. Solar cell temperature appeared to be the primary determinant of reliability and warranty period, with concentration being the secondary determinant. A 30-year warranty for these 1 mm2-sized GaAs cells (manufactured according to a light emitting diode-like approach) may be offered for both cell concentrations (700 and 1050 suns) if the solar cell is operated at a working temperature of 65°C.

Preliminary temperature accelerated life test (ALT) on lattice mismatched triple-junction concentrator solar cells-on-carriers

A temperature accelerated life test on concentrator lattice mismatched Ga0.37In0.63P/Ga0.83In0.17As/Ge triple-junction solar cells-on-carrier is being carried out. The solar cells have been tested at three different temperatures: 125, 145 and 165°C and the nominal photo-current condition (500X) is emulated by injecting current in darkness. The final objective of these tests is to evaluate the reliability, warranty period, and failure mechanism of these solar cells in a moderate period of time. Up to now only the test at 165°C has finished. Therefore, we cannot provide complete reliability information, but we have carried out preliminary data and failure analysis with the current results.

UM ESTUDO PRELIMINAR DAS INFLUÊNCIAS DO MERCADO DE COMMODITIES NA VARIAÇÃO DO CUSTO DA ALIMENTAÇÃO DO TRABALHADOR: ANÁLISE DE RISCO DA SEGURANÇA ALIMENTAR E NUTRICIONAL

A Segurança Alimentar e Nutricional do trabalhador brasileiro é uma das formas de garantia de saúde e conseqüente aumento de produtividade refletido pelo compromisso do PAT Programa de Alimentação do Trabalhador que completou 30 anos em 2006. O objetivo do estudo é relacionar a variação de preços das commodities de alimentos presentes na refeição do trabalhador de acordo com o sistema normativo do PAT, identificando possíveis conseqüências negativas à Segurança Alimentar do Trabalhador no Brasil. A metodologia, por meio da análise de regressão múltipla, utiliza os dados de ICV Índice de Custo de Vida - de alimentação fora do domicílio como proxy a alimentação do trabalhador. Os resultados sugerem que os alimentos que apresentaram variação negativa com os tipos de refeições analisadas, como a carne suína e a soja, podem ser substituídos por outro valor nutricional semelhante como a carne bovina, o frango e o óleo de milho. Apenas a variação do preço do feijão foi seguida pelo aumento do preço do prato comercial, cuja alternativa é a mudança na maneira de oferecer a refeiç ão ao trabalhador, como os restaurantes por quilo. Diante do cenário exposto, há indícios de que a variação de preços dos alimentos no mercado de commodities teria pouca influência no preço final das refeições, mas a discussão em torno da futura escassez de oferta de alimentos devido ao aumento da população mundial e a mudança dos padrões alimentares com as sociedades urbanizadas insere o risco da SAN no contexto político e econômico da nutrição.(AU)

UM ESTUDO PRELIMINAR DAS INFLUÊNCIAS DO MERCADO DE COMMODITIES NA VARIAÇÃO DO CUSTO DA ALIMENTAÇÃO DO TRABALHADOR: ANÁLISE DE RISCO DA SEGURANÇA ALIMENTAR E NUTRICIONAL

A Segurança Alimentar e Nutricional do trabalhador brasileiro é uma das formas de garantia de saúde e conseqüente aumento de produtividade refletido pelo compromisso do PAT Programa de Alimentação do Trabalhador que completou 30 anos em 2006. O objetivo do estudo é relacionar a variação de preços das commodities de alimentos presentes na refeição do trabalhador de acordo com o sistema normativo do PAT, identificando possíveis conseqüências negativas à Segurança Alimentar do Trabalhador no Brasil. A metodologia, por meio da análise de regressão múltipla, utiliza os dados de ICV Índice de Custo de Vida - de alimentação fora do domicílio como proxy a alimentação do trabalhador. Os resultados sugerem que os alimentos que apresentaram variação negativa com os tipos de refeições analisadas, como a carne suína e a soja, podem ser substituídos por outro valor nutricional semelhante como a carne bovina, o frango e o óleo de milho. Apenas a variação do preço do feijão foi seguida pelo aumento do preço do prato comercial, cuja alternativa é a mudança na maneira de oferecer a refeiç ão ao trabalhador, como os restaurantes por quilo. Diante do cenário exposto, há indícios de que a variação de preços dos alimentos no mercado de commodities teria pouca influência no preço final das refeições, mas a discussão em torno da futura escassez de oferta de alimentos devido ao aumento da população mundial e a mudança dos padrões alimentares com as sociedades urbanizadas insere o risco da SAN no contexto político e econômico da nutrição.(AU)

Two-Dimensional Failure Modeling with Minimal Repair

In this paper, we discuss two-dimensional failure modeling for a system where degradation is due to age and usage. We extend the concept of minimal repair for the one-dimensional case to the two-dimensional case and characterize the failures over a two-dimensional region under minimal repair. An application of this important result to a rnanufacturer's servicing costs for a two-dimensional warranty policy is given and we compare the minimal repair strategy with the strategy of replacement of failure. (C) 2003 Wiley Periodicals, Inc.

UM ESTUDO PRELIMINAR DAS INFLUÊNCIAS DO MERCADO DE COMMODITIES NA VARIAÇÃO DO CUSTO DA ALIMENTAÇÃO DO TRABALHADOR: ANÁLISE DE RISCO DA SEGURANÇA ALIMENTAR E NUTRICIONAL

A Segurança Alimentar e Nutricional do trabalhador brasileiro é uma das formas de garantia de saúde e conseqüente aumento de produtividade refletido pelo compromisso do PAT Programa de Alimentação do Trabalhador que completou 30 anos em 2006. O objetivo do estudo é relacionar a variação de preços das commodities de alimentos presentes na refeição do trabalhador de acordo com o sistema normativo do PAT, identificando possíveis conseqüências negativas à Segurança Alimentar do Trabalhador no Brasil. A metodologia, por meio da análise de regressão múltipla, utiliza os dados de ICV Índice de Custo de Vida - de alimentação fora do domicílio como proxy a alimentação do trabalhador. Os resultados sugerem que os alimentos que apresentaram variação negativa com os tipos de refeições analisadas, como a carne suína e a soja, podem ser substituídos por outro valor nutricional semelhante como a carne bovina, o frango e o óleo de milho. Apenas a variação do preço do feijão foi seguida pelo aumento do preço do prato comercial, cuja alternativa é a mudança na maneira de oferecer a refeiç ão ao trabalhador, como os restaurantes por quilo. Diante do cenário exposto, há indícios de que a variação de preços dos alimentos no mercado de commodities teria pouca influência no preço final das refeições, mas a discussão em torno da futura escassez de oferta de alimentos devido ao aumento da população mundial e a mudança dos padrões alimentares com as sociedades urbanizadas insere o risco da SAN no contexto político e econômico da nutrição.(AU)

Assessment of Information Asymmetry

2000 Mathematics Subject Classification: 62P20, 91B42

Professionalism and Ethics in Hospitality

In their discussion - Professionalism and Ethics in Hospitality - by James R. Keiser, Associate Professor and John Swinton, Instructor, Hotel, Restaurant and Institutional Management, The Pennsylvania State University, Keiser and Swinton initially offer: “Referring to “the hospitality profession” necessitates thinking of the ethics of that profession and how ethics can be taught. The authors discuss what it means for the hospitality industry to be a profession.” The authors will have you know, a cursory nod to the term or description, profession and/or professional, is awarded to the hospitality industry at large; at least in an academic sense. Keiser and Swinton also want you to know that ethics, and professionalism are distinctly unique concepts, however, they are related. Their intangible nature does make them difficult, at best, to define, but ethics in contemporary hospitality has, to some degree, been charted and quantified. “We have left the caveat emptor era, and the common law, the Uniform Commercial Code, and a variety of local ordinances now dictate that the goods and services hospitality offers carry an implied warranty of merchantability,” the authors inform you. About the symbiotic relationship between ethics and professionalism, the authors say this: The less precise a code of ethics goes, the general rule, the fewer claims the group has to professional status.” The statement above may be considered a cornerstone principle. “However, the mere existence of an ethical code (or of professional status, for that matter) does not ensure ethical behavior in any group,” caution Keiser and Swinton. “Codes of ethics do not really define professionalism except as they adopt a group's special, arcane, exclusionary jargon. Worse, they can define the minimum, agreed-upon standards of conduct and thereby encourage ethical corner-cutting,” they further qualify the thought. And, in bridging academia, Keiser and Swinton say, “Equipped now with a sense of the ironies and ambiguities inherent in labeling any work "professional," we can turn to the problem of instilling in students a sense of what is professionally ethical. Students appear to welcome this kind of instruction, and while we would like to think their interest comes welling up from altruism and intellectual curiosity rather than drifting down as Watergate and malpractice fallout, our job is to teach, not to weigh the motives that bring us our students, and to provide a climate conducive to ethical behavior, not supply a separate answer for every contingency.” Keiser and Swinton illustrate their treatise on ethics via the hypothetical tale [stylized case study] of Cosmo Cuisiner, who manages the Phoenix, a large suburban restaurant. Cosmo is “…a typical restaurant manager faced with a series of stylized, over-simplified, but illustrative decisions, each with its own ethical skew for the students to analyze.” A shortened version of that case study is presented. Figure 1 outlines the State Restaurant Association Code of Ethics.

“Eu quero ver se a justiça vai funcionar mesmo”: a resolubilidade dos casos de abuso sexual contra crianças e adolescentes no município de Natal/RN

This study presents the issue of Children and Youth sexual violence from a critical eye in assessing the actions of the organs of defense and protection in cases of sexual abuse against children and adolescents in the city of Natal / RN. We aimed to perform this evaluation from the investigation of 05 cases of child and adolescent victims of sexual abuse that were answered by Precinct Specializing in Defense of Children and Adolescents (DCA), considering the service flow of cases, the articulation between the organs that make up System Warranty rights (SGD), the record of the complaint, as well as the elapsed time between the record of the complaint and the accountability of the offender. Thus, the present study consists in an analysis from the quantitative and qualitative theoretical-methodological approach assuming 'sexual violence in their social, historical, cultural, legal and economic dimensions. The route established between the knowledge about the object and the method of analysis involved: literature about the conceptual discussion on sexual violence, analyzing quantitative data provided by DCA, as well as semi-structured interviews with victims and those responsible for the professionals working in institutions of the defense agencies. Is apprehended in this study that the situations of violence against children is a multifaceted phenomenon that has expressions from ancient societies, assuming a peculiarity in contemporary society to consider the juvenile population as subjects of rights. Furthermore, it was possible to identify the lack of effectiveness, with respect to the actions of the organs of defense in intervention situations of sexual abuse now investigated as yet not actually configure a process of articulation between these bodies from the perspective of ensuring rights and break the cycle of violence.

Processo de construção do conhecimento a partir do diálogo ensino-serviço na ótica dos profissionais de saúde

INTRODUCTION: In Brazil, the health training policies have been going through deep changes, which are the fruits of the sanitary reform and of the breakage with the biomedical model, still hegemonic. Nevertheless, the paradigm of comprehensiveness is being introduced in health and, in order to consolidate this concept, the training has been gaining new methodological approaches. One can mention the teaching-service interaction (education-health system/citizenship health), whose proposal enables the expansion of the perception of the health-disease process, as well as the warranty of compromises of training in relation to SUS. OBJECTIVE: Understand, from health professionals, the relevance of teaching-service-community interaction, vocational training of students of the Faculty of Health Sciences / UFRN. METHODOLOGICAL PROCEDURES: This study is grounded on qualitative approach. The technique used to obtain research data was the focus group. Two focus groups (FG) were accomplished in two family basic health units of the municipality of Santa Cruz – RN, where there is participation of professionals of the Family Health Strategy. The discussions were performed from a previously elaborated script. The analysis of results was held from the categorical thematic content technique. RESULTS: The study had the participation of 18 health professionals, and 13 (72%) were females. For these professionals, the teaching-service interaction enables the student to understand the model of comprehensive health care, since the contact with the community enhances its perception about the health-disease process, but also enables recognizing the importance of teamwork to comprehensive health care. FINAL CONSIDERATIONS: The results highlight the importance of a policy of reorientation within the context of training so that students have an early contact with the service and therefore develop technical skills within the context in which they are inserted.

Justificación y error en Descartes: un argumento pragmatista en la validación cartesiana del criterio de claridad y distinción

La percepción clara y distinta es el elemento sobre el que se asienta la certeza metafísica de Descartes. Con todo, el planteamiento de los argumentos escépticos referidos a la duda metódica cartesiana ha evidenciado la necesidad de hallar una justificación al propio criterio de la percepción clara y distinta. Frente a los intentos basados en la indubitabilidad de la percepción o en la garantía surgida de la bondad divina, se defenderá una justificación alternativa pragmatista.