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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Untersuchungen zur Optimierung von elektrischen Schaltungsträgern auf der Basis von Keramik-Metall-Verbunden

Günther, Michael January 2008 (has links)
Zugl.: Dresden, Techn. Univ., Diss., 2008
2

How to Estimate the Unmodulated Carrier Power Level of a Modulated Telemetry Signal

Law, Eugene 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / This paper will present methods to both measure the unmodulated carrier power of a modulated signal and to estimate the unmodulated carrier power level from the measured power spectrum. The unmodulated carrier power level is needed to convert measured spectra into units of dBc.
3

Switchmode Power Supply Miniaturization with Emphasis on Integrated Passive Components on Prefired High Performance Ceramic Substrates

Hoagland, Richard W. 24 August 1999 (has links)
This Dissertation is a study of Switched Mode Power Supply (SMPS) miniaturization and how to effectively use the available technologies to achieve the ultimate goal of a reduced size without loss of functionality while maintaining a cost effective design. This research investigates several methods used to obtain low loss, highly compact power supplies. Within these constraints, the Dissertation investigates the issues of design, materials, and cost in order to design and achieve these miniaturized power supplies. This research addresses high performance ceramic, passive component integration. Three key issues; electrical characterization, thermal analysis and simulation, and material characterization, are examined in this work. Thick film passive components (capacitors and resistors) on AlN have been developed. Also, guidelines for the design implementation and steps necessary to integrate these passive components on prefired alumina (Al2O3) and aluminum nitride (AlN) ceramic surfaces, for power electronic applications, have been generated. The use of aluminum nitride, as a high performance ceramic substrate and the resulting issues concerning compatible inks, have been investigated. Since a sizable amount of heat is generated by power electronic circuits, the integrated components are analyzed with respect to tolerance and degeneration over a range of temperatures and frequencies. Thick film capacitors on the order of 120pF/mm2 with breakdown voltage ratings of 250V have been developed on prefired AlN. Resistors were developed with impedances ranging from 10W to 10MegW. Thermal measurements, of these resistors, show that the thermal conductivity of the aluminum nitride with passivation layer is two to three times that of alumina. Several versions of a typical SMPS boost circuit have been generated using Direct Bond Copper (DBC) on ceramic, Insulated Metal Substrate (IMS), Printed Circuit Boards (PCB), and prefired ceramic thick film technology. The integrated passive components developed are applied on prefired ceramic versions and compared to the DBC, IMS and PCB versions. A small daughter board consisting of the boost circuit control is introduced to further supplement miniaturization and reduce cost. The daughter board uses thick film technology with integrated thick film resistors. The design of the mother board, which houses the power boost section,can be designedand implemented on virtually any type of substrate (PCB, DBC, IMS, or conventional thick film). The fabrication and testing of each version is reported in this work. / Ph. D.
4

In vivo metabolism of 7H-dibenzo[c.g.] carbazole (DBC) and benzo[a]pyrene (BaP)

SINER, ANGELA 11 March 2002 (has links)
No description available.
5

The function of Nup358 in nucleocytoplasmic transport / Die Funktion von Nup358 im nukleocytoplasmatischen Transport

Wälde, Sarah 23 August 2010 (has links)
No description available.
6

High Frequency, High Power Density GaN-Based 3D Integrated POL Modules

Ji, Shu 14 March 2013 (has links)
The non-isolated POL converters are widely used in computers, telecommunication systems, portable electronics, and many other applications. These converters are usually constructed using discrete components, and operated at a lower frequency around 200 ~ 600 kHz to achieve a decent efficiency at the middle of 80\'s%. The passive components, such as inductors and capacitors, are bulky, and they occupy a considerable foot-print. As the power demands increase for POL converters and the limited real estate of the mother board, the POL converters must be made significantly smaller than what they have demonstrated to date. To achieve these goals, two things have to happen simultaneously. The first is a significant increase in the switching frequency to reduce the size and weight of the inductors and capacitors. The second is to integrate passive components, especially magnetics, with active components to realize the needed power density.<br />Today, this concept has been demonstrated at a level less than 5A and a power density around 300-700W/in3 by using silicon-based power semiconductors. This might address the need of small hand-held equipment such as PDAs and smart phones. However, it is far from meeting the needs for applications, such as netbook, notebook, desk-top and server applications where tens and hundreds of amperes are needed.<br />After 30 years of silicon MOSFET development, the silicon has approached its theoretical limits. The recently emerged GaN transistors as a possible candidate to replace silicon devices in various power conversion applications. GaN devices are high electron mobility transistors (HEMT) and have higher band-gap, higher electron mobility, and higher electron velocity than silicon devices, and offer the potential benefits for high frequency power conversions. By implementing the GaN device, it is possible to build the POL converter that can achieve high frequency, high power density, and high efficiency at the same time. GaN technology is in its early stage; however, its significant gains are projected in the future. The first generation GaN devices can outperform the state-of-the-art silicon devices with superior FOM and packaging. <br />The objective of this work is to explore the design of high frequency, high power density 12 V input POL modules with GaN devices and the 3D integration technique. This work discusses the fundamental differences between the enhancement mode and depletion mode GaN transistors, the effect of parasitics on the performance of the high frequency GaN POL, the 3D technique to integrate the active layer with LTCC magnetic substrate, and the thermal design of a high density module using advanced substrates with improved thermal conductivity.<br />The hardware demonstrators are two 12 V to 1.2 V highly integrated 3D POL modules, the single phase 10 A module and two phase 20 A module, all built with depletion mode GaN transistors and low profile LTCC inductors.<br /> / Master of Science
7

UM MÉTODO PARA SELEÇÃO DE SOFTWARE NA ENGENHARIA DE REQUISITOS / A METHOD FOR SELECTION OF SOFTWARE IN SOFTWARE ENGINEERING REQUIREMENTS

CANTANHÊDE FILHO, Paulino Almeida 14 March 2005 (has links)
Made available in DSpace on 2016-08-17T14:52:57Z (GMT). No. of bitstreams: 1 Paulino de Almeida Cantanhede Filho.pdf: 1682767 bytes, checksum: a5fce1801fd45fddf7e98305e0e9b053 (MD5) Previous issue date: 2005-03-14 / Guidelines for evaluation and selection of COTS (Commercial-Off-The-Shelf) products. Comes a methodology for the Development based on COTS (DBC) in the Requirements Engineering, being approached the evaluation phases and selection of DBC. The method is divided in three phases, that are divided in activities orienting by actions that seek to the quality of the information for a socket of decision in an automated and oriented way for defined evaluation criteria during the Requirements Engineering. This approach divide the requirements in three levels: Fundamental, Contractual and Desirable. The functional and no-functional requirements are treated in an equalitarian way. / Este trabalho apresenta diretrizes para avaliação e seleção de produtos COTS (Commercial- Off-The-Shelf). Apresenta-se uma metodologia para o Desenvolvimento Baseado em COTS (DBC) na Engenharia de Requisitos, abordando-se as fases de avaliação e seleção do DBC. O método está dividido em três fases, que por sua vez estão divididas em atividades direcionadas por ações que visam à qualidade das informações para uma tomada de decisão de forma automatizada e orientada por critérios de avaliação definidos durante a Engenharia de Requisitos. Esta abordagem divide os requisitos em três níveis, são eles: Fundamental, Contratual e Desejável. Os requisitos funcionais e não-funcionais são tratados de forma igualitária.
8

Formal relationships in sequential object systems

Kerfoot, Eric D. January 2010 (has links)
Formal specifications describe the behaviour of object-oriented systems precisely, with the intent to capture all properties necessary for correctness. Relationships between objects, and in a broader sense the relationship between whole components, may not be adequately captured by specifications. One critical component of specifications having a role in relationships are invariants which define a constraint between multiple objects. If an object's invariant relies on external objects for its conditions, correct operations which abide by their specifications modifying these external objects may violate the constraint. Such an invariant defines a relationship between multiple objects which is unsound since it does not adequately describe the responsibilities which the objects in the relationship have to each other. The root cause of this correctness loophole is the failure of specifications to capture such relationships adequately as well as their correctness requirements. This thesis addresses this shortcoming in a number of ways, both for individual objects in a sequential environment, and between concurrent components which are defined as specialized object types. The proposed Colleague Technique [29] defines sound invariants between two object types using classical Design-by-Contract [35] methodologies. Additional invariant conditions introduced through the technique ensure that no correct operation may produce a post-state which does not satisfy all invariants satisfied by the pre-state. Relationships between objects, as well as their correct specification and management, are the subjects of this thesis. Those relationships between objects which can be described by invariants are made sound with the Colleague Technique, or the lightweight ownership type system that accompanies it. Behavioural correctness beyond these can be addressed with specifications in a similar manner to sequential systems without concurrency, in particular with the use of runtime assertion checking [11].
9

Seleção automatizada de componentes de software orientada por métricas estruturais e informações de reúso

Alexandre Segundo, Jailton Maciel 30 August 2014 (has links)
Made available in DSpace on 2015-05-14T12:36:52Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2070301 bytes, checksum: e15a4fc1a4f27fd39d2a55b1400d522b (MD5) Previous issue date: 2014-08-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The great difficulty of selecting software components is still an obstacle to achieving the success of Component-Based Development (CBD). With the growing market for components, the tendency is always to increase the number of options for assembling applications in different contexts, making it impractical to manual selection. Dealing with a problem of gigantic and complex search space, it is required automation performed by optimization techniques. The proposed approach aims to automate the process of selecting components using techniques of Search-Based Software Engineering (SBSE), whose optimization technique is driven by structural metrics (i.e., connections between components of a software architecture) and information reuse (i.e., aggregated values to the component itself). The metrics used in this component selection context are intended to assess the structural perspective of an architectural instance, since they predict possible integration problems between implementations of components produced by third parties. Note that other proposals ignore this perspective and focus only on the component itself. In addition, reuse information can bring an alternative to represent the perception of the developers about the quality attributes of the software components in a reuse scenario as: the degree of consumers' satisfaction who have already purchased this component and the number of downloads of it. The proposed evaluation is carried out through experiments, which are validated by applying statistical tests. / A grande dificuldade de selecionar componentes de software ainda é um obstáculo para alcançar o sucesso do Desenvolvimento Baseado em Componentes (DBC). Com o crescimento do mercado de componentes, a tendência é sempre aumentar o número de opções para montagem de aplicações em diferentes contextos, tornando impraticável a seleção manual. Tratando de um problema com gigantesco espaço de busca e complexo, é requerida a automatização efetuada por técnicas de otimização. O trabalho proposto visa automatizar o processo de seleção de componentes utilizando técnicas da Engenharia de Software Baseada em Busca (ESBB), cuja técnica de otimização é orientada por métricas estruturais (avaliam as conexões entre componentes de uma arquitetura de software) e informações de reúso (i.e., valores correspondentes ao reúso de software agregados ao próprio componente). As métricas utilizadas neste contexto de seleção de componentes têm o propósito de avaliar a perspectiva estrutural de uma instância arquitetural, já que elas preveem possíveis problemas de integração entre implementações de componentes produzidas por terceiros, além de que muitos problemas ignoram essa perspectiva e só focam no componente em si. Já as informações de reúso trazem consigo uma alternativa para representar a percepção dos desenvolvedores sobre os atributos de qualidade dos componentes de software em cenários de reúso, tais como: o grau de satisfação dos consumidores que já adquiriram tal componente e o número de downloads do mesmo. A avaliação da proposta é conduzida através de experimentos, que são validados aplicando testes estatísticos.
10

Fédération de données semi-structurées avec XML

Dang-Ngoc, Tuyet-Tram 18 June 2003 (has links) (PDF)
Contrairement aux données traditionnelles, les données semi-structurées sont irrégulières : des données peuvent manquer, des concepts similaires peuvent être représentés par différents types de données, et les structures même peuvent être mal connues. Cette absence de schéma prédéfini, permettant de tenir compte de toutes les données du monde extérieur, présente l'inconvénient de complexifier les algorithmes d'intégration des données de différentes sources. Nous proposons une architecture de médiation basée entièrement sur XML. L'objectif de cette architecture de médiation est de fédérer des sources de données distribuées de différents types. Elle s'appuie sur le langage XQuery, un langage fonctionnel conçu pour formuler des requêtes sur des documents XML. Le médiateur analyse les requêtes exprimées en XQuery et répartit l'exécution de la requête sur les différentes sources avant de recomposer les résultats. L'évaluation des requêtes doit se faire en exploitant au maximum les spécificités des données et permettre une optimisation efficace. Nous décrivons l'algèbre XAlgebre à base d'opérateurs conçus pour XML. Cette algèbre a pour but de construire des plans d'exécution pour l'évaluation de requêtes XQuery et traiter des tuples d'arbres XML. Ces plans d'exécution doivent pouvoir être modélisés par un modèle de coût et celui de coût minimum sera sélectionné pour l'exécution. Dans cette thèse, nous définissons un modèle de coût pour les données semi-structurées adapté à notre algèbre. Les sources de données (SGBD, serveurs Web, moteur de recherche) peuvent être très hétérogènes, elles peuvent avoir des capacités de traitement de données très différentes, mais aussi avoir des modèles de coût plus ou moins définis. Pour intégrer ces différentes informations dans l'architecture de médiation, nous devons déterminer comment communiquer ces informations entre le médiateur et les sources, et comment les intégrer. Pour cela, nous utilisons des langages basés sur XML comme XML-Schema et MathML pour exporter les informations de métadonnées, de formules de coûts et de capacité de sources. Ces informations exportées sont communiquées par l'intermédiaire d'une interface applicative nommée XML/DBC. Enfin, des optimisations diverses spécifiques à l'architecture de médiation doivent être considérées. Nous introduisons pour cela un cache sémantique basé sur un prototype de SGBD stockant efficacement des données XML en natif.

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