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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.
111

Process Models for Laser Engineered Net Shaping

Kummailil, John 29 April 2004 (has links)
The goal of this dissertation is to develop a model relating LENSâ„¢ process parameters to deposited thickness, incorporating the effect of substrate heating. A design review was carried out, adapting the technique of functional decomposition borrowed from axiomatic design. The review revealed that coupling between the laser path and laser power caused substrate heating. The material delivery mechanism was modeled and verified using experimental data. It was used in the derivation of the average deposition model which predicted deposition based on build parameters, but did not incorporate substrate heating. The average deposition model appeared capable of predicting deposited thickness for single line, 1- layer and 2-layer builds, performing best for the 1- layer builds which were built under essentially isothermal conditions. This model was extended to incorporate the effect of substrate heating, estimated using an energy partition approach. The energy used for substrate heating was modeled as a series of timed heating events from an instantaneous point heat source along the path of the laser. The result was called the spatial deposition model, and was verified using the same set of experimental data. The model appeared capable of predicting deposited thickness for single line, 1- layer and 2- layer builds and was able to predict the characteristic temperature rise near the borders as the laser reversed direction.
112

Post-silicon Functional Validation with Virtual Prototypes

Cong, Kai 03 June 2015 (has links)
Post-silicon validation has become a critical stage in the system-on-chip (SoC) development cycle, driven by increasing design complexity, higher level of integration and decreasing time-to-market. According to recent reports, post-silicon validation effort comprises more than 50% of the overall development effort of an 65nm SoC. Though post-silicon validation covers many aspects ranging from electronic properties of hardware to performance and power consumption of whole systems, a central task remains validating functional correctness of both hardware and its integration with software. There are several key challenges to achieving accelerated and low-cost post-silicon functional validation. First, there is only limited silicon observability and controllability; second, there is no good test coverage estimation over a silicon device; third, it is difficult to generate good post-silicon tests before a silicon device is available; fourth, there is no effective software robustness testing approaches to ensure the quality of hardware/software integration. We propose a systematic approach to accelerating post-silicon functional validation with virtual prototypes. Post-silicon test coverage is estimated in the pre-silicon stage by evaluating the test cases on the virtual prototypes. Such analysis is first conducted on the initial test suite assembled by the user and subsequently on the expanded test suite which includes test cases that are automatically generated. Based on the coverage statistics of the initial test suite on the virtual prototypes, test cases are automatically generated to improve the test coverage. In the post-silicon stage, our approach supports coverage evaluation of test cases on silicon devices to ensure fidelity of early coverage evaluation. The generated test cases are issued to silicon devices to detect inconsistencies between virtual prototypes and silicon devices using conformance checking. We further extend the test case generation framework to generate and inject fault scenario with virtual prototypes for driver robustness testing. Besides virtual prototype-based fault injection, an automatic driver fault injection approach is developed to support runtime fault generation and injection for driver robustness testing. Since virtual prototype enables early driver development, our automatic driver fault injection approach can be applied to driver testing in both pre-silicon and post-silicon stages. For preliminary evaluation, we have applied our coverage evaluation and test generation to several network adapters and their virtual prototypes. We have conducted coverage analysis for a suite of common tests on both the virtual prototypes and silicon devices. The results show that our approach can estimate the test coverage with high fidelity. Based on the coverage estimation, we have employed our automatic test generation approach to generate additional tests. When the generated test cases were issued to both virtual prototypes and silicon devices, we observed significant coverage improvement. And we detected 20 inconsistencies between virtual prototypes and silicon devices, each of which reveals a virtual prototype or silicon device defect. After we applied virtual prototype-based fault injection approach to virtual prototypes for three widely-used network adapters, we generated and injected thousands of fault scenarios and found 2 driver bugs. For automatic driver fault injection, we have applied our approach to 12 widely used drivers with either virtual prototypes or silicon devices. After testing all these drivers, we found 28 distinct bugs.
113

Conception et réalisation de pièces prototypes fonctionnelles en usinage sur machines-outils à commande numérique 5 axes

Salloum, Tammam 21 October 2009 (has links) (PDF)
A ce jour, les pièces prototypes réalisées à partir de poudre ou de liquide n'ont pas forcement des propriétés mécaniques suffisantes ni la précision requise pour être placées dans des mécanismes fonctionnels. L'objectif de ce travail est de réaliser des mécanismes prototypes fonctionnels, c'est-à-dire capables de fonctionner sur un banc d'essais ou en service dans son milieu d'utilisation (sur un véhicule par exemple). L'approche URP "Usinage Rapide de Prototype" proposée consiste à décomposer une pièce complexe de type carter par exemple, en plusieurs strates épaisses usinées sur machine outil à commande numérique 5 axes et assemblées. Le tranchage en strates est déterminé de sorte que les entités fonctionnelles ne soient pas découpées et que l'usinage soit réalisable, y compris pour les entités à obtenir dans l'épaisseur de la pièce. Le type et la position des dispositifs de centrage et de fixation des strates sont ensuite choisis. Deux montages d'usinage originaux et une gamme d'usinage ont été conçus pour réaliser chaque strate en deux phases. Un protocole de vérification de l'usinabilité a été proposé. Un carter a été réalisé sur la machine MIKRON UCP 710 du laboratoire avec une analyse des précisions obtenues. Une pièce d'essai a été définie pour permettre l'évaluation des capabilités de la méthode.
114

Un modèle multidimensionnel pour un processus d'analyse en ligne de résumés flous

Naoum, Lamiaa 22 November 2006 (has links) (PDF)
Le travail présenté dans cette thèse traite de l'exploration et de la manipulation des résumés de bases de données de taille significative. Les résumés produits par le système SaintEtiQ sont des vues matérialisées multi-niveaux de classes homogènes de données, présentées sous forme de collections d'étiquettes floues disponibles sur chaque attribut. La contribution de cette thèse repose sur trois points. En premier lieu nous avons défini un modèle de données logique appelé partition de résumés, par analogie avec les cubes de données OLAP, dans le but d'offrir à l'utilisateur final un outil de présentation des données sous forme condensée et adaptée à l'analyse. En second lieu, nous avons défini une collection d'opérateurs algébriques sur l'espace multidimensionnel des partitions de résumés. Ces opérateurs sont à la base d'une algèbre de manipulation des résumés. Cette algèbre prend en compte les spécificités du modèle de résumé que nous traitons. Nous avons adapté la ma jorité des opéra- teurs d'analyse proposés dans les systèmes OLAP. Ainsi, nous avons identifié : les opérateurs de base issus de l'algèbre relationnelle, les opérateurs de changement de granularité et les opérateurs de restructuration. Ces résultats offrent de nouvelles perspectives pour l'exploitation effective des résumés dans un système décisionnel. Finalement, pour compléter ce travail, nous nous sommes intéressés à la représen- tation des résumés et des partitions de résumés linguistiques, notamment pour en fournir une présentation claire et concise à l'utilisateur final. Appliquée à une hiérar- chie de résumés produite par le système SaintEtiQ, l'approche tente de construire des prototypes flous représentant les résumés.
115

Gestaltningstekniker i interaktionsdesign : en fråga om syfte och publik

Johansson, Maria January 2006 (has links)
<p>Denna studie är en fallstudie av ett privat sjukvårdsföretag. Studien syftar till att undersöka hur olika gestaltningstekniker</p><p>samt gruppers sammansättning kan påverka diskussioner kring design och därmed fungera som strukturerande resurser för</p><p>samtalet. Studien vidgar begreppet prototyper till att hantera mer än de delar som behandlats i tidigare forskning: medium,</p><p>detaljrikedom och närhet till slutprodukt.</p><p>Datainsamling har skett vid sex fokusgruppstillfällen där tre olika grupper (inom olika delar av en och samma organisation:</p><p>användare hos kund, användare hos systemleverantören och systemutvecklare hos leverantören) har fört en diskussion kring</p><p>designen utifrån tre olika gestaltningstekniker (gränssnittsskisser, scenarios och dynamiska datorprototyper).</p><p>Diskussionerna har sedan analyserats i termer av domäner för interaktionsdesign och aspekter av IT-systemet i användning.</p><p>Studiens huvudsakliga slutsatser är att gestaltningstekniker påverkar vilka domäner och aspekter som diskuteras varför</p><p>designern kan välja gestaltningsteknik efter vad han eller hon vill få ut av diskussionen. Skisserna bedöms ge den mest</p><p>heltäckande diskussionen, medan scenarios fungerar bäst för dem som inte är teknikvana och tar då upp struktur och</p><p>funktion. Datorprototypen lämpar sig bäst för diskussion kring interaktion och presentation. Men gruppens sammansättning</p><p>påverkar diskussionen i högre utsträckning än gestaltningsteknikerna. Därför dras även slutsatsen att det är viktigt att</p><p>designern känner sin publik och anpassar valet av gestaltningsteknik efter målgruppen.</p> / <p>This thesis investigates how different prototyping techniques and compositions of groups can influence discussions about</p><p>design and therefore function as structuring resources for the discussion. This thesis widens the conception of prototypes to</p><p>include more than the issues that have been discussed in previous research: medium, wealth of details and closeness to the</p><p>final product.</p><p>Data has been collected through six focus groups where three different groups (within different parts of one organization;</p><p>users at client, users at system supplier, and systems developers at supplier) have discussed the design with the help of the</p><p>different prototyping techniques (sketches, scenarios and dynamic computer prototypes).</p><p>The discussions where analyzed in terms of domains for interaction design and different aspects of the system in use.</p><p>The main conclusions of this thesis are that prototyping techniques influence which domains and aspects are discussed.</p><p>Therefore the designer can choose prototyping technique depending on what he or she wants to discuss about the design.</p><p>The sketches provides the most complete discussion, while scenarios works best with those that are not knowledgeable</p><p>about IT-systems and then the discussion deals with structure and function. The computer prototype is best suited for</p><p>discussing interaction and presentation. But the composition of the group has more influence on the discussion than the</p><p>choice of prototyping technique. Therefore the conclusion is drawn that it is important that the designer knows his or her</p><p>audience and adjusts the choice of prototyping technique to the composition of the group.</p>
116

Simple haptics : Sketching perspectives for the design of haptic interactions

Moussette, Camille January 2012 (has links)
Historically, haptics—all different aspects of the sense of touch and its study—has developed around very technical and scientific inquiries. Despite considerable haptic research advances and the obviousness of haptics in everyday life, this modality remains mostly foreign and unfamiliar to designers. The guiding motif of this research relates to a desire to reverse the situation and have designers designing for and with the haptic sense, for human use and looking beyond technical advances. Consequently, this thesis aims to nurture the development of haptics from a designerly perspective, leading to a new field of activities labeled haptic interaction design. It advances that haptic attributes and characteristics are increasingly part of the qualities that make up the interactions and the experiences we have with objects and the interfaces that surround us, and that these considerations can and ought to be knowingly and explicitly designed by designers. The book encompasses an annotated research through design exploration of the developing field of haptic interaction design, building on a considerable account of self-initiated individual design activities and empirical-style group activities with others. This extensive investigation of designing haptic interactions leads to the Simple Haptics proposition, an approach to ease the discovery and appropriation of haptics by designers. Simple Haptics consists in a simplistic, rustic approach to the design of haptic interactions, and advocates an effervescence of direct perceptual experiences in lieu of technical reverence. Simple Haptics boils down to three main traits: 1) a reliance on sketching in hardware to engage with haptics; 2) a fondness for basic, uncomplicated, and accessible tools and materials for the design of haptic interactions; and 3) a strong focus on experiential and directly experiencable perceptual qualities of haptics.  Ultimately, this thesis offers contributions related to the design of haptic interactions. The main knowledge contribution relates to the massification of haptics, i.e. the intentional realization and appropriation of haptics—with its dimensions and qualities—as a non-visual interaction design material. Methodologically, this work suggests a mixed longitudinal approach to haptics in a form of a well-grounded interplay between personal inquiries and external perspectives. The book also presents design contributions as ways to practically, physically and tangibly access, realize and explore haptic interactions. Globally these contributions help make haptics concrete, graspable, sensible and approachable for designers. The hope is to inspire design researchers, students and practitioners to discover and value haptics as a core component of any interaction design activities.
117

A methodology for creating expert-based quantitative models for early phase design

Engler, William O., III 08 April 2013 (has links)
Early systems engineering and requirements definition requires quantitative information about potential solutions prior to having sufficient information or time to develop detailed models. This research develops and demonstrates a transparent and repeatable process for rapidly creating quantitative models that leverage existing expert knowledge. This process is built upon established modeling frameworks and current literature for low fidelity modeling and hierarchical expert-based methods. The process includes system definition using interactive morphological analysis and gathering information from subject-matter experts with computer-based interfaces in order to create a series of linear performance models. Available volunteers provided data for a relevant aerospace design to test the process as a whole and several hypotheses about specific methodological decisions made during the development. The collected data was analyzed for similarity among participants and for similarity to model parameters of an existing trusted truth model. The results of the analysis demonstrated the ability for expert-based models to accurately match the behavior of the truth models and of historical data.
118

Algoritmos de Geração de Protótipos Para Bases Desbalanceadas

Oliveira, Dayvid Victor Rodrigues de 25 February 2014 (has links)
Submitted by Lucelia Lucena (lucelia.lucena@ufpe.br) on 2015-03-06T19:37:29Z No. of bitstreams: 2 DISSERTAÇÃO Dayvid Victor Rodrigues de Oliveira.pdf: 798881 bytes, checksum: 3b4ac40fda11573b025340c2b03e8903 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-06T19:37:29Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO Dayvid Victor Rodrigues de Oliveira.pdf: 798881 bytes, checksum: 3b4ac40fda11573b025340c2b03e8903 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014-02-25 / Técnicas de redução de instâncias são técnicas usadas para reduzir a quantidade de instâncias em um conjunto de dados. Estas técnicas podem atuar removendo dados redundantes ou gerando novos dados. As instâncias resultantes são chamadas de protótipos. Técnicas de seleção de protótipos, são técnicas de redução de instâncias que realizam esta tarefa selecionando um subconjunto do conjunto de dados original. Já as técnicas de geração de protótipos, são técnicas de redução de instâncias que criam instâncias que não necessariamente pertencem ao conjunto de dados original. Algoritmos evolucionários têm sido frequentemente utilizados em seleção de protótipos, tal abordagem é chamada de evolutionary prototype selection. Algumas bases de dados do mundo real possuem muitas instâncias de uma classe, a classe majoritária, e poucas de outra, classe minoritária, estas bases são chamadas de bases desbalanceadas. Em tais bases, muitos algoritmos de redução de instâncias se tornam inviáveis, retornando muitas instâncias da classe majoritária e poucas, ou até nenhuma, da classe minoritária. Este efeito é ainda mais acentuado em técnicas de remoção de ruídos. Neste trabalho, são propostas duas técnicas de geração de protótipos que minimizam o efeito de desbalanceamento entre classes. A primeira proposta é o Creative Steady-State Memetic Algorithm (CSSMA), um algoritmo de geração de protótipos que utiliza um algoritmo evolucionário, incorporando uma busca local, para encontrar o conjunto de protótipos artificiais que maximiza a função de aptidão. Esta técnica é inspirada no Steady-State Memetic Algorithm, uma das melhores técnicas de seleção de protótipos na literatura, tanto em redução quanto em classificação. A segunda proposta é o Adaptive Self- Generating Prototypes (ASGP), esta técnica gera instâncias levando em consideração o tamanho do maior agrupamento de cada classe. O ASGP é uma derivação do Self-Generating Prototypes (SGP), considerada uma das técnicas de geração de protótipos de maior poder de generalização, sendo, porém, ineficiente em bases desbalanceadas. As bases de dados usadas nos experimentos são do módulo imbalanced datasets do KEEL software, dicotômicas, e com diferentes níveis de desbalanceamento. Cada base é dividida em 5 partições para aplicação do k-fold cross validation (k=5). As métricas usadas para avaliar a performance dos algoritmos foram a area under the ROC curve (AUC) e a taxa de redução. Para comparar os resultados, foi utilizado o teste estatístico de Wilcoxon. Os resultados mostram que o CSSMA foi superior em taxa de acerto, AUC, a outros algoritmos evolucionários de redução de instâncias recentemente propostos. O ASGP também obteve uma AUC superior ao Self-Generating Prototypes 2, versão mais atual do SGP.
119

Hybride Prototypen im Design

Lorenz, Sebastian, Klemm, Maria, Krzywinski, Jens 19 July 2017 (has links) (PDF)
Aus der Einführung: "Die Verwendung von Prototypen besitzt eine zentrale Rolle bei der Produktentwicklung und im Designprozess (Camere et al. 2016). Wie Camere und Bordegoni feststellen hat sich der Fokus der Designdisziplin auf Funktionalität um die Aspekte der Usability und der User Experience erweitert. Damit einhergehend hat sich auch die Rolle der Prototypen von Funktionsmustern und Präsentationsobjekten um die Funktionen als Evaluierungs- und Versuchsobjekte ergänzt. Die Integration von Nutzern in den Designprozess ist dabei ein weiterer Punkt bei denen Prototypen ein wichtiges Werkzeug zur Kommunikation und kooperativen Arbeit liefert (Schneider 1996). Die Integration von Prototyping-Methoden in den unterschiedlichen Phasen des Designprozesses führt zu unterschiedlichen Anforderungen hinsichtlich der Form und Aufgabe der Prototypen. Entsprechend vielfältig sind die heute verwendeten Arten von Prototyping. ..."
120

Investigating and improving assessment practices in Physics in secondary schools in Mozambique

Januario, Francisco Maria 25 September 2008 (has links)
Assessment, an integral part of teaching and learning, is a planned process of identifying, gathering and interpreting information about the performance of students. However, concerns have been raised about how assessment is being conducted in schools and so the aim of this study is to investigate and improve assessment practices used by Grade 12 secondary school Physics teachers in Mozambique, Africa. The study addresses the question of what assessment practices do Grade 12 teachers in Physics in Mozambique apply and how can they be improved? and it adopted a twofold research approach. A Baseline Survey aimed at gaining an overall impression of the assessment practices used by secondary school Physics teachers and an Intervention Study aimed at producing improvements on teacher assessment practices. The preliminary research followed a survey research method, while the intervention applied an educational design research approach. In the survey three questions were investigated: (i) What assessments practices do Grade 12 Physics teachers apply? (ii) What is the quality of the assessment practices? and (iii) How relevant can the assessment practices be for student learning?To address these questions a purposive sample of 12 Physics teachers, four school directors and five educational officers was selected. The survey was conducted in six secondary schools purposefully selected throughout the country and data were collected via interviews, questionnaires, classroom observations and written notes. The Intervention Study was designed to answer the question of how teacher assessment practices can be improved.This phase of the study involved a design, a classroom tryout, and a systematic evaluation of a series of exemplary Physics assessment materials (prototypes) in a context of demonstration experiments. The prototypes were developed for the concepts of force and inertia and their validity and practicality were verified using appraisal by experts, university students, teachers, and students. Classroom tryout was conducted with two teachers and their 62 students in two secondary schools. Baseline Survey findings indicate that the most used assessment practices in schools are paper-and-pencil tests, verbal tests, and homework, while projects, portfolios, and peer assessments are the less frequently used ones. Oral communication during lessons, written work, presentations, notebooks, laboratory work, and ability to solve problems were used as quality criteria for the teachers’ assessment. It was shown that the most frequently assessed student activity was written work, followed by the ability of students to solve problems, while laboratory work was the activity that was never assessed by many of the researched teachers. Another quality criterion used was the type of feedback given by teachers to students, which indicated that teachers were giving expressed (both congratulatory and critical), personal and timely feedback. It emerged that teachers often involve the students in the evaluation of their performance through reflection of assessment results and in addition, encourage students to engage in active learning. Findings from the Intervention Study indicate that (i) teachers liked the presentation and structure of the materials following the Predict-Observe-Explain (POE) strategy and regarded their personal commitment as crucial for achieving the desired experimental results; (ii) students also liked most the POE strategy because it allowed them to develop their own explanations of the observed events and highlighted the role of teachers during the tryout as crucial for the success of the experiments. The main conclusion of this study is that assessment practices undertaken by Physics teachers in Mozambican secondary schools are of poor quality and there is a need for improvement. This must be done by developing and applying exemplary assessment materials with the potential to improve performance assessment practices associated with demonstration experiments in Physics. The study recommends that the Ministry of Education and Culture and teacher training institutions should promote the training of teachers in developing exemplary assessment materials for their own use in schools. These materials should contain specific guidelines on how to conduct effective assessment practices. / Thesis (PhD)--University of Pretoria, 2008. / Curriculum Studies / unrestricted

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