873 resultados para Computer-Aided Engineering and Design


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Mode of access: Internet.

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Tesi hau Solarus AB enpresaren konzentratzailedun eguzki kolektore fotovoltaiko termikoei (C-PVT) buruz doa eta bi helburu nagusi ditu. Lehena Solarus-eko oraingo diseinuaren alderaketak diseinatzea da, MaReCo (Maximum Reflector Collector) diseinuaren eta parabola puruaren alderaketa batzuekin batera. Diseinu hauetan eguzki zelulen ebaketa berriak daude barruan eta 4 busbar-eko eguzki zeluletan oinarritua dago. Honi esker analisi sakon bat egin ahalko da hargailu eta estruktura diseinuak konparatuz. Bigarren helburua Solarus AB-k Gävleko unibertsitatean (HiG) kokaturik dituen kolektoreen errendimendu elektriko eta termikoa aztertzean datza. Datuak simulazio eta software espezifikoen bidez lortu dira eta ondoren Microsoft Excel®-en aztertu. Bi proiektu txikiagoak egin dira ere enpresan, bata eguzki kolektore fotovoltaiko termikoen merkatuaren ikerketan datza eta bestea eguzki kolektoreen produkzio prozesuaren gida batean. Hargailuen eta estrukturaren diseinu berriak preparatuta utzi dira prototipoen hurreneko eraikuntzarako eta proiektuarekin jarraitzeko etorkizuneko lan bat planeatu da. Unibertsitateko instalakuntzaren analisiari dagokionez, errendimendu elektriko eta termikoa estimatuena baino nabarmenki txikiagoak izan dira.

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The main objective for physics based modeling of the power converter components is to design the whole converter with respect to physical and operational constraints. Therefore, all the elements and components of the energy conversion system are modeled numerically and combined together to achieve the whole system behavioral model. Previously proposed high frequency (HF) models of power converters are based on circuit models that are only related to the parasitic inner parameters of the power devices and the connections between the components. This dissertation aims to obtain appropriate physics-based models for power conversion systems, which not only can represent the steady state behavior of the components, but also can predict their high frequency characteristics. The developed physics-based model would represent the physical device with a high level of accuracy in predicting its operating condition. The proposed physics-based model enables us to accurately develop components such as; effective EMI filters, switching algorithms and circuit topologies [7]. One of the applications of the developed modeling technique is design of new sets of topologies for high-frequency, high efficiency converters for variable speed drives. The main advantage of the modeling method, presented in this dissertation, is the practical design of an inverter for high power applications with the ability to overcome the blocking voltage limitations of available power semiconductor devices. Another advantage is selection of the best matching topology with inherent reduction of switching losses which can be utilized to improve the overall efficiency. The physics-based modeling approach, in this dissertation, makes it possible to design any power electronic conversion system to meet electromagnetic standards and design constraints. This includes physical characteristics such as; decreasing the size and weight of the package, optimized interactions with the neighboring components and higher power density. In addition, the electromagnetic behaviors and signatures can be evaluated including the study of conducted and radiated EMI interactions in addition to the design of attenuation measures and enclosures.

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SpicA FAR infrared Instrument, SAFARI, is one of the instruments planned for the SPICA mission. The SPICA mission is the next great leap forward in space-based far-infrared astronomy and will study the evolution of galaxies, stars and planetary systems. SPICA will utilize a deeply cooled 2.5m-class telescope, provided by European industry, to realize zodiacal background limited performance, and high spatial resolution. The instrument SAFARI is a cryogenic grating-based point source spectrometer working in the wavelength domain 34 to 230 μm, providing spectral resolving power from 300 to at least 2000. The instrument shall provide low and high resolution spectroscopy in four spectral bands. Low Resolution mode is the native instrument mode, while the high Resolution mode is achieved by means of a Martin-Pupplet interferometer. The optical system is all-reflective and consists of three main modules; an input optics module, followed by the Band and Mode Distributing Optics and the grating Modules. The instrument utilizes Nyquist sampled filled linear arrays of very sensitive TES detectors. The work presented in this paper describes the optical design architecture and design concept compatible with the current instrument performance and volume design drivers.

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The current knowledge revised in this article describes a wide range of facilities in common use on dairy cattle farms in warm climates. A dairy cattle farm consists of several facilities, such as housing system, yards, manure pits, milking center, environmental protection structures, forage storage, and several machines for different facilities. Any facility design tends to be a compromise, often between many factors, and no single solution will be optimal for all concerned.

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Although there is a vast amount of literature on website evaluation, relatively little has been written about the analysis of websites of small and medium-sized enterprises (SME). This paper examines a comprehensive set of content and design features of 915 websites of Portuguese SME, as well as the relationship between these features and enterprise size. The results indicate that the majority of the websites are used to convey information, rather than to make transactions, support networking and collaboration or to interact dynamically with users. Accessibility or privacy and security features are not common among websites. Web 2.0 features have a low presence in SME websites, but social media emerged as a construct. In contrast with existing literature, the study has found that website content and design features are positively related with enterprise size. The contributions and implications are discussed together with avenues for further research.

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Dyspnea is a common and disabling symptom of respiratory and heart diseases, which is growing in incidence. During hospital admission, breathlessness is under-diagnosed and under-treated, although there are treatments available for controlling the symptom. We have developed a tailored implementation strategy directed to medical staff to promote the application of these pharmacological and non-pharmacological tools in dealing with dyspnea. The primary aim is to decrease the rate of patients that do not receive an adequate relief of dyspnea. This is a four-stage quasi-experimental study. The intervention consists in two teaching talks that will be taught in Cardiology and Respiratory Medicine Departments. The contents will be prepared by Palliative Care specialists, based on available tools for management of dyspnea and patients' needs. A cross-sectional study of dyspnea in hospitalized patients will be performed before and after the intervention to ascertain an improvement in dyspnea intensity due to changes in medical practices. The last phase consists in the creation of consensus protocols for dyspnea management based in our experience. The results of this study are expected to be of great value and may change clinical practice in the near future and promote a changing for the better of dyspnea care.

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Fluids are important because of their preponderance in our lives. Fluid mechanics touches almost every aspect of our daily lives, and it plays a central role in many branches of science and technology. Therefore, it is a challenging and exciting field of scientific activity due to the complexity of the subject studied and the breadth of the applications. The quest for advances in fluid mechanics, as in other scientific fields, emerge from analytical, computational (CFD) and experimental studies. The improvement in our ability to describe, predict and control the phenomena played (and plays) key roles in the technological breakthroughs. The present theme issue of “Fluid and Heat Flow: Simulation and Optimization” collects a selection of papers. selection of papers presented at Special Session “Fluid Flow, Energy Transfer and Design

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Literature emphasises the sparse research focused in collaborative and open approaches in the design conceptualisation stage, also known as the Fuzzy Front-End (FFE). Presently, the most challenging discussion arising from this specific field of research lies in understanding on whether or not to structure the referred conceptual stage. Accordingly, the established hypothesis behind this study sustains that a structured approach in the FFE would benefit the interdisciplinary dialogue. Therefore, two objectives support this study: to understand the benefits of an interdisciplinary approach in the FFE, and to test one proposed model for this conceptual stage. By means of a small-scale design experiment, this paper pretends to give additional contributions to this area of research, in the context of new product development (NPD). The general research supporting this specific study aims to conceptualise in the area of newly and futuristic aircraft configurations. Hence, this same topic based the conceptualisation process in the conducted ideation sessions, which are conducted by five different teams of three elements each. The results of the different ideation sessions reinforce the contemporary paradigm of Open Innovation (OI), which is based in trust and communication to better collaborate. The postulated hypothesis for this study is partially validated as teams testing the proposed and structured model generally consider that its usage would benefit the integration of different disciplines. Besides, a general feeling that a structured approach integrates different perspectives and gives creativity a focus pervades. Nevertheless, the small-scale of the design experiment attributes some limitations to this study, despite giving new insights in how to better organise coming and more sustained studies. Interestingly, the importance of sketching as an interdisciplinary means of communication is underlined with the obtained results.

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In this thesis, we deal with the design of experiments in the drug development process, focusing on the design of clinical trials for treatment comparisons (Part I) and the design of preclinical laboratory experiments for proteins development and manufacturing (Part II). In Part I we propose a multi-purpose design methodology for sequential clinical trials. We derived optimal allocations of patients to treatments for testing the efficacy of several experimental groups by also taking into account ethical considerations. We first consider exponential responses for survival trials and we then present a unified framework for heteroscedastic experimental groups that encompasses the general ANOVA set-up. The very good performance of the suggested optimal allocations, in terms of both inferential and ethical characteristics, are illustrated analytically and through several numerical examples, also performing comparisons with other designs proposed in the literature. Part II concerns the planning of experiments for processes composed of multiple steps in the context of preclinical drug development and manufacturing. Following the Quality by Design paradigm, the objective of the multi-step design strategy is the definition of the manufacturing design space of the whole process and, as we consider the interactions among the subsequent steps, our proposal ensures the quality and the safety of the final product, by enabling more flexibility and process robustness in the manufacturing.

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The research solved the historiographic lacuna about Leonardo Ricci’s work in the United States focusing on the span 1952-1972 as a fundamental period for the architect's research, which moved from the project for the community space to macrostructures. The considered period is comprised between Ricci’s first travel to the United States and the date of his resignation from the University of Florida, one year before his resignation from the deanship of the faculty of architecture of Florence (1973). The research retraced philologically the stages of Ricci’s activity in the U.S.A. unveiling the premises and results of his American transfer, and to what extent it marked a turning period for his work as educator and designer and for the wider historiographic contest of the Sixties. The American transfer helped him grounding his belief in avoiding a priori morphological results in favor of what he called the “form-act” design method. Ricci’s research in the U.S.A. is described in his books Anonymous (XX century) and City of the Earth (unpublished). In them and in Ricci’s projects one common thread is traceable: the application of the “form-act” as the best tool to conceive urban design, a discipline established in the United States during Ricci’s first stay at M.I.T., in which he encountered the balance point between architecture and urban planning, between the architect’s sign and his being anonymous, between the collective and the individual dimension. With the notions of “anonymous architecture” and “form-act”, Urban Design and “open work” are the key words to understand Ricci’s work in the United States and in Italy. Urban design’s main goal to design the city as a collective work of art was the solution of that dychothomous research that enlivened Ricci’s work and one possible answer to that tension useful for him to seek the truth of architecture.

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Due to the interest of general public and the industrial stakeholders, new challenges and demands are rising in aircraft design. The sustainability is taking its place amongst more traditional design factors, such as safety, performances and costs. Sustainability is both environmental and economic, and among the factors contributing to economic sustainability, there is also passengers' comfort. In order to win these two challenges, they must be considered in the early stages of aircraft design. In this work, the focus is on emissions generation and acoustic comfort, aiming at reducing pollution and internal noise in the preliminary design phases. These results can be achieved with both unconventional aircraft configurations and advanced materials, which also require new numerical formulations to be assessed. In this research, on one hand, the windowless configuration for a commercial aircraft is studied with traditional preliminary design methods in order to achieve a weight reduction and consequently a return in terms of emissions and costs. On the other hand, a new class of insulating materials, the acoustic metamaterials, is applied on the passenger cabin lining panels. The complex kinematic behaviour of these advanced materials is studied through the Carrera's Unified Formulation, that enhances a wide class of powerful refined shell and beam theories with a unique formulation.

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In the frame of inductive power transfer (IPT) systems, arrays of magnetically coupled resonators have received increasing attention as they are cheap and versatile due to their simple structure. They consist of magnetically coupled coils, which resonate with their self-capacitance or lumped capacitive networks. Of great industrial interest are planar resonator arrays used to power a receiver that can be placed at any position above the array. A thorough circuit analysis has been carried out, first starting from traditional two-coil IPT devices. Then, resonator arrays have been introduced, with particular attention to the case of arrays with a receiver. To evaluate the system performance, a circuit model based on original analytical formulas has been developed and experimentally validated. The results of the analysis also led to the definition of a new doubly-fed array configuration with a receiver that can be placed above it at any position. A suitable control strategy aimed at maximising the transmitted power and the efficiency has been also proposed. The study of the array currents has been carried out resorting to the theory of magneto-inductive waves, allowing useful insight to be highlighted. The analysis has been completed with a numerical and experimental study on the magnetic field distribution originating from the array. Furthermore, an application of the resonator array as a position sensor has been investigated. The position of the receiver is estimated through the measurement of the array input impedance, for which an original analytical expression has been also obtained. The application of this sensing technique in an automotive dynamic IPT system has been discussed. The thesis concludes with an evaluation of the possible applications of two-dimensional resonator arrays in IPT systems. These devices can be used to improve system efficiency and transmitted power, as well as for magnetic field shielding.