19 resultados para 39795
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Rupestris stem pitting (rSP), a graft-transmissible grapevine disease, can be identified only by its reaction (pitted wood) on inoculated Vitis rupestris ‘St. George.’ DsRNA was extracted from grapevines from California and Canada that indexed positive for rSP on St. George. Two distinct dsRNA species (B and C) (Mr = 5.3 × 106 and 4.4 × 106, respectively) were detected from the stem tissue of rSP-positive samples. Although similar dsRNA species (B and C) were detected in extracts of grapevines from New York, the association of dsRNA B and C with rSP in New York samples was not consistent. Also, eight different dsRNAs, known to be associated with the powdery mildew fungus, Uncinula necator, were detected in leaves of New York samples. In New York, the dsRNAs were not observed in leaves or stem samples collected from June through late August during the 1988 and 1989 growing seasons, suggesting that dsRNA detection in the grape tissue is variable throughout the season. We suggest that dsRNA species B and C are associated with rSP disease. The inconsistent results with New York samples are discussed.
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讨论了第二层次跟踪轴线长度的温度天扰性,引入“骨架热协变”概念。给出了结晶熔融相变的一个重要的微观形成因素和晶胞参数热膨胀差异的形成机理。
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Se presenta una experiencia extraescolar de tres días en Cuenca con estudiantes de BUP en la que la diversidad de los contenidos y la eliminación radical de elementos cotidianos (aulas, televisión, ambiente familiar) permiten el máximo aprovechamiento en un corto periodo de tiempo. Los objetivos son: estudiar el ecosistema y la explotación humana de los recursos naturales y cómo ésta influye en la historia de la comarca y la ciudad; relacionar las formas de la naturaleza con las obras de arte abstractas, y acentuar la relación del dibujo con el resto de las materias.
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Premio Educación y Sociedad 1995 en la modalidad de Material Didáctico no editado
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Thermoelectric generators (TEG) are solid state devices and are able to convert thermal energy directly into electricity and thus could play an important role in waste heat recovery in the near future. Half-Heusler (HH) compounds with the general formula MNiSn (M = Ti, Zr, Hf) built a promising class of materials for these applications because of their high Seebeck coefficients, their environmentally friendliness and their cost advantage over conventional thermoelectric materials.rnrnMuch of the existing literature on HH deals with thermoelectric characterization of n-type MNiSn and p-type MCoSb compounds. Studies on p-type MNiSn-based HHs are far fewer in number. To fabricate high efficient thermoelectric modules based on HH compounds, high performance p-type MNiSn systems need to be developed that are compatible with the existing n-type HH compounds. This thesis explores synthesis strategies for p-type MNiSn based compounds. In particular, the efficacy of transition metals (Sc, La) and main group elements (Al, Ga, In) as acceptor dopants on the Sn-site in ZrNiSn, was investigated by evaluating their thermoelectric performance. The most promising p-type materials could be achieved with transition metal dopants, where the introduction of Sc on the Zr side, yielded the highest Seebeck coefficient in a ternary NiSn-based HH compound up to this date. Hall effect and band gap measurements of this system showed, that the high mobility of minority carrier electrons dominate the transport properties at temperatures above 500 K. It could be shown that this is the reason, why n-type HH are successful TE materials for high temperature applications, and that p-types are subjected to bipolar effects which will lead to diminished thermoelectric efficiencies at high temperatures.rnrnTo complement the experimental investigations on different metal dopants and their influence on the TE properties of HH compounds, numerical solutions to the Boltzmann transport equation were used to predict the optimum carrier concentration where the maximum TE efficiency occurs for p-type HH compounds. The results for p-type samples showed that can not be treated within a simple parabolic band model approach, due to bipolar and multi-band effects.rnrnThe parabolic band model is commonly used for bulk TE materials. It is most accurate when the transport properties are dominated by one single carrier type. Since the transport properties of n-type HH are dominated by only one carrier type (high mobility electrons), it could be shown, that the use of a simple parabolic band model lead to a successful prediction of the optimized carrier concentration and thermoelectric efficiency in n-type HH compounds. rn
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Aus: Relationis historicae semestralis vernalis continuatio ; 1672, Frühj.
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Los retos y oportunidades a los que se enfrentan las organizaciones y administraciones de las primeras décadas del siglo XXI se caracterizan por una serie de fuerzas perturbadoras como la globalización, el avance de las tecnologías emergentes y el desequilibrio económico, que están actuando como impulsores de la transformación del mercado. La acción conjunta de estos factores está obligando a todas las empresas industriales a tener que trabajar con mayores y más exigentes niveles de productividad planteándose continuamente como mejorar y lograr satisfacer los requerimientos de los clientes. De esta situación surge la necesidad de volver a plantearse de nuevo ¿quién es el cliente?, ¿qué valora el cliente? y ¿cómo se pueden generan beneficios sostenibles? La aplicación de esta reflexión a la industria naval militar marca los objetivos a los que esta tesis doctoral busca dar respuesta. El primer objetivo, de carácter general, consiste en la definición de un modelo de negocio sostenible para la industria naval militar del 2025 que se adapte a los requisitos del cliente y al nuevo escenario político, económico, social, tecnológico y ambiental que rodea esta industria. El segundo objetivo, consecuencia del modelo general, trata de desarrollar una metodología para ejecutar programas de apoyo al ciclo de vida del “buque militar”. La investigación se estructura en cuatro partes: en la primera se justifica, por un lado, la necesidad del cambio de modelo y por otro se identifican los factores estructurantes para la definición del modelo. La segunda parte revisa la literatura existente sobre uno de los aspectos básicos para el nuevo modelo, el concepto Producto-Servicio. La tercera parte se centra totalmente en la industria naval militar estudiando los aspectos concretos del sector y, en base al trabajo de campo realizado, se identifican los puntos que más valoran las Marinas de Guerra y como estas gestionan al buque militar durante todo su ciclo de vida. Por último se presentan los principios del modelo propuesto y se desarrollan los pilares básicos para la ejecución de proyectos de Apoyo al Ciclo de Vida (ACV). Como resultado de la investigación, el modelo propuesto para la industria naval militar se fundamenta en once principios: 1. El buque militar (producto de alto valor añadido) debe ser diseñado y construido en un astillero del país que desarrolla el programa de defensa. 2. El diseño tiene que estar orientado al valor para el cliente, es decir, se tiene que diseñar el buque militar para que cumpla su misión, eficaz y eficientemente, durante toda su vida operativa, asegurando la seguridad del buque y de las personas y protegiendo el medio ambiente de acuerdo con las regulaciones vigentes. 3. La empresa debe suministrar soluciones integrales de apoyo al ciclo de vida al producto. 4. Desarrollar y mantener las capacidades de integración de sistemas complejos para todo el ciclo de vida del buque militar. 5. Incorporar las tecnologías digitales al producto, a los procesos, a las personas y al propio modelo de negocio. 6. Desarrollar planes de actuación con el cliente domestico a largo plazo. Estos planes tienen que estar basados en tres premisas: (i) deben incluir el ciclo de vida completo, desde la fase de investigación y desarrollo hasta la retirada del buque del servicio; (ii) la demanda debe ser sofisticada, es decir las exigencias del cliente, tanto desde la óptica de producto como de eficiencia, “tiran” del contratista y (iii) permitir el mantenimiento del nivel tecnológico y de las capacidades industriales de la compañía a futuro y posicionarla para que pueda competir en el mercado de exportación. 7. Impulsar el sector militar de exportación mediante una mayor actividad comercial a nivel internacional. 8. Fomentar la multilocalización ya que representa una oportunidad de crecimiento y favorece la exportación posibilitando el suministro de soluciones integrales en el país destino. 9. Reforzar la diplomacia institucional como palanca para la exportación. 10. Potenciar el liderazgo tecnológico tanto en producto como en procesos con políticas activas de I + D+ i. 11. Reforzar la capacidad de financiación con soluciones innovadoras. El segundo objetivo de esta tesis se centra en el desarrollo de soluciones integrales de Apoyo al Ciclo de Vida (ACV). La metodología planteada trata de minimizar la brecha entre capacidades y necesidades a lo largo de la vida operativa del barco. Es decir, el objetivo principal de los programas de ACV es que la unidad conserve durante toda su vida operativa, en términos relativos a las tecnologías existentes, las capacidades equivalentes a las que tendrá cuando entre en servicio. Los ejes de actuación para conseguir que un programa de Apoyo al Ciclo de Vida cumpla su objetivo son: el diseño orientado al valor, la ingeniería de Apoyo al Ciclo de Vida, los proyectos de refresco de tecnología, el mantenimiento Inteligente y los contratos basados en prestaciones. ABSTRACT On the first decades of the 21st century, organizations and administrations face challenges and come across opportunities threatened by a number of disruptive forces such as globalization, the ever-changing emerging technologies and the economic imbalances acting as drivers of the market transformation. This combination of factors is forcing all industrial companies to have more and higher demanding productivity levels, while bearing always in mind how to improve and meet the customer’s requirements. In this situation, we need to question ourselves again: Who is the customer? What does the customer value? And how can we deliver sustainable economic benefits? Considering this matter in a military naval industry framework sets the goals that this thesis intends to achieve. The first general goal is the definition of a new sustainable business model for the 2025 naval industry, adapted to the customer requirements and the new political, economic, social, technological and environmental scenario. And the second goal that arises as a consequence of the general model develops a methodology to implement “warship” through life support programs. The research is divided in four parts: the first one justifies, on the one hand, the need to change the existing model and, on the other, identifies the model structural factors. On the second part, current literature regarding one of the key issues on the new model (the Product-Service concept) is reviewed. Based on field research, the third part focuses entirely on military shipbuilding, analyzing specific key aspects of this field and identifying which of them are valued the most by Navies and how they manage through life cycles of warships. Finally, the foundation of the proposed model is presented and also the basic grounds for implementing a Through Life Support (TLS) program are developed. As a result of this research, the proposed model for the naval industry is based on eleven (11) key principles: 1. The warship (a high added value product) must be designed and built in a shipyard at the country developing the defense program. 2. Design must be customer value oriented, i.e.warship must be designed to effectively fulfill its mission throughout its operational life, ensuring safety at the ship and for the people and protecting the environment in accordance with current regulations. 3. The industry has to provide integrated Through Life Support solutions. 4. Develop and maintain integrated complex systems capabilities for the entire warship life cycle. 5. Introduce the product, processes, people and business model itself to digital technologies. 6. Develop long-term action plans with the domestic customer. These plans must be based on three premises: (i) the complete life cycle must be included, starting from the research and development stage throughout the ship’s disposal; (ii) customer demand has to be sophisticated, i.e. customer requirements, both from the efficiency and product perspective, "attract" the contractor and (iii) technological level and manufacturing capabilities of the company in the future must be maintained and a competitive position on the export market has to be achieved. 7. Promote the military exporting sector through increased international business. 8. Develop contractor multi-location as it entails an opportunity for growth and promote export opportunities providing integrated solutions in the customer's country. 9. Strengthen institutional diplomacy as a lever for export. 10. Promote technological leadership in both product and processes with active R & D & I policies (Research & Development & Innovation) 11. Strengthen financing capacity through innovative solutions. The second goal of this thesis is focused on developing integrated Through Life Support (TLS) solutions. The proposed methodology tries to minimize the gap between needs and capabilities through the ship operational life. It means, the main TLS program objective is to maintain the ship’s performance and capabilities during operational life, in relative terms to current technologies, equivalent to those the ship had when it entered service. The main actions to fulfill the TLS program objectives are: value-oriented design, TLS engineering, technology updating projects, intelligent maintenance and performance based contracts.