889 resultados para 010203 Calculus of Variations Systems Theory and Control Theory
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Software is a key component in many of our devices and products that we use every day. Most customers demand not only that their devices should function as expected but also that the software should be of high quality, reliable, fault tolerant, efficient, etc. In short, it is not enough that a calculator gives the correct result of a calculation, we want the result instantly, in the right form, with minimal use of battery, etc. One of the key aspects for succeeding in today's industry is delivering high quality. In most software development projects, high-quality software is achieved by rigorous testing and good quality assurance practices. However, today, customers are asking for these high quality software products at an ever-increasing pace. This leaves the companies with less time for development. Software testing is an expensive activity, because it requires much manual work. Testing, debugging, and verification are estimated to consume 50 to 75 per cent of the total development cost of complex software projects. Further, the most expensive software defects are those which have to be fixed after the product is released. One of the main challenges in software development is reducing the associated cost and time of software testing without sacrificing the quality of the developed software. It is often not enough to only demonstrate that a piece of software is functioning correctly. Usually, many other aspects of the software, such as performance, security, scalability, usability, etc., need also to be verified. Testing these aspects of the software is traditionally referred to as nonfunctional testing. One of the major challenges with non-functional testing is that it is usually carried out at the end of the software development process when most of the functionality is implemented. This is due to the fact that non-functional aspects, such as performance or security, apply to the software as a whole. In this thesis, we study the use of model-based testing. We present approaches to automatically generate tests from behavioral models for solving some of these challenges. We show that model-based testing is not only applicable to functional testing but also to non-functional testing. In its simplest form, performance testing is performed by executing multiple test sequences at once while observing the software in terms of responsiveness and stability, rather than the output. The main contribution of the thesis is a coherent model-based testing approach for testing functional and performance related issues in software systems. We show how we go from system models, expressed in the Unified Modeling Language, to test cases and back to models again. The system requirements are traced throughout the entire testing process. Requirements traceability facilitates finding faults in the design and implementation of the software. In the research field of model-based testing, many new proposed approaches suffer from poor or the lack of tool support. Therefore, the second contribution of this thesis is proper tool support for the proposed approach that is integrated with leading industry tools. We o er independent tools, tools that are integrated with other industry leading tools, and complete tool-chains when necessary. Many model-based testing approaches proposed by the research community suffer from poor empirical validation in an industrial context. In order to demonstrate the applicability of our proposed approach, we apply our research to several systems, including industrial ones.
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A synbiotic is a formulation containing both probiotics and prebiotics. This study aims to evaluate the effect of supplementation with a synbiotic containing Enterococcus faecium strain E1707 (NCIMB 10415) in preventing or controlling diarrhoea and other gastrointestinal signs in boarded canine radiotherapy patients. A double-blind, randomized, placebocontrolled clinical trial was carried out in 21 adult dogs undergoing radiotherapy and boarded for a duration period of 2 to 3 weeks to treat their cancers. Dogs were randomly divided between two groups: A and B, the synbiotic and placebo group, respectively. The content of the sachets was added to the food once daily. Faecal score was assessed daily, and dogs were also monitored for the development of diarrhoea and other gastrointestinal signs such as weight loss, reduced appetite and vomiting. The results from descriptive statistics seem to favour group B, however these findings were not validated with inferential statistics due to insufficient statistical sample power. Because of this, it is not possible to make conclusions about the benefits of synbiotic as supportive treatment for dogs undergoing radiotherapy. All results should be considered to be preliminary, until they are elucidated by further animal inclusion.
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The purpose of this work is to obtain micrometer sized spherical particles of silica and silica-chromium from sodium silicate. Spherical particles were prepared by sol-gel method from hydrolysis to polycondensation of aqueous sodium silicate in alcohol medium. Chromium was added to the system for some samples. Compositions and morphologies were achieved by changing the precipitation agent. X-ray diffractometry, electrophoretic mobility, infrared spectroscopy and scanning electron microscopies were carried out on these particles to identify phases, determine particle mobility, morphology, particle sizes, shapes and order at short distance. Non-crystalline silica particles with spherical shapes and micrometric size were obtained. The surface potentials of the silica particles differed from that of the silica-chromium particles. (C) 1999 Elsevier B.V. B.V. All rights reserved.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Este proyecto trata de diseñar el sistema eléctrico y de control de potencia de una maqueta del túnel aerodinámico ACLA-16 de la Universidad Politécnica de Madrid (UPM). Dicha maqueta se utiliza para estudiar el efecto de la capa límite atmosférica, debido a su importancia en el impacto sobre estructuras civiles. Primero se desarrolla una parte teórica sobre qué son los túneles aerodinámicos, las aplicaciones que tienen y conceptos básicos acerca de la capa límite atmosférica. Luego se analiza el diseño geométrico de la maqueta del túnel y se detallan los elementos que debe tener el sistema eléctrico. Además, se realiza una simulación por ordenador con un programa de CFD (Fluent) para comparar los resultados experimentales reales con los resultados numéricos de la simulación para comprobar si se pueden extraer resultados aceptables por ordenador y así ahorrar costes y tiempo en el estudio de ensayos.
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El proyecto está basado en el estudio de la planta de potencia de un túnel aerodinámico. Para ello se ha realizado una breve introducción definiendo qué es un túnel aerodinámico, cuál es su propósito, qué tipos hay, etc. Posteriormente se ha escogido un tipo concreto de túnel entre todas las posibilidades y se ha procedido a su estudio. Se ha definido una forma y unas dimensiones y tras calcular las pérdidas de carga, se ha seleccionado la planta de potencia necesaria para compensar dichas pérdidas, dimensionándose también las conexiones de esta desde la acometida de potencia eléctrica. Por último se han dimensionado las conexiones correspondientes a la iluminación y los servicios que competen al túnel aerodinámico.
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La utilización de túneles aerodinámicos en ingeniería civil está cada vez más demandada debido al actual desarrollo urbanístico, esto es, la necesidad de edificios cada vez más altos en los que concentrar mayor cantidad de población, puentes y estructuras que faciliten el paso de medios de transporte alternativos, la importancia de los aspectos artísticos en la construcción (además de los funcionales), etc. Son muchos los factores que pueden hacer necesario el ensayo de alguna de esas estructuras en un túnel aerodinámico, y no existe un criterio universal a la hora de decidir si conviene o no hacerlo.
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"Serial no. J-100-60."
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"A summary report, January 1989."
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Includes bibliographical references and index.
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Mode of access: Internet.
Information systems audit and control issues for enterprise management systems: Qualitative evidence