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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.
71

Development of RF front end prototype compliant with the 802.11a standard for wireless applications

Papageorgiou, Nikolaos A. 01 December 2003 (has links)
No description available.
72

Malmöspanaren - En digital plattform för deltagande förvaltning av Malmö stads cykelvägnät

Ehrenberg, Nils, Landstedt, Simon January 2012 (has links)
In this project we have explored digital tools for service management on the bicycle paths of Malmö. This was done through the participation of citizens in order to attempt to discern how such interactions can be eased using a mobile app, as well as how this app can be designed in order to appear trustworthy with user friendly interactions.We have explored this field by using goal-oriented design through interviews, prototyping and user tests. We have created a digital prototype as a possible solution for how the interactions can be done.Throughout the process interviews were held and user tests with selected members of the user group. To explore the concepts we have used paper prototypes in order to establish the design and then defining the interactions with the help of a digital prototype.Finally we have concluded that a general app for bikers in the city would be functional and that a longer study in the effects of such an app would be interesting as a continuation of this work.
73

Εκτίμηση παραμέτρων μαθηματικών προτύπων κελιών καυσίμου στερεού οξειδίου

Χαραλαμπίδου, Χριστίνα 04 September 2013 (has links)
Οι σημαντικές περιβαλλοντικές επιπτώσεις που απορρέουν από τις ανθρώπινες δραστηριότητες έχουν οδηγήσει την επιστημονική κοινότητα σε αναζήτηση πιο αποδοτικών και φιλικών προς το περιβάλλον τεχνολογιών παραγωγής ενέργειας. Σε αυτά τα πλαίσια η τεχνολογία των κελιών καυσίμων έχει προσελκύσει σημαντικό ενδιαφέρον. Τα κελιά καυσίμου μετατρέπουν τη χημική ενέργεια που είναι αποθηκευμένη σε ένα καύσιμο απ’ ευθείας σε ηλεκτρική, χωρίς να υπόκεινται στους περιορισμούς του κύκλου Carnot. Συγκριτικά με τα υπόλοιπα κελιά καυσίμου, το κελί καυσίμου στερεού οξειδίου (SOFC), ξεχωρίζει κυρίως λόγω της υψηλής απόδοσής του. Στην παρούσα εργασία γίνεται εκτίμηση των παραμέτρων μαθηματικών προτύπων κελιών καυσίμου στερεού οξειδίου, με σκοπό να αναλυθούν οι ηλεκτροχημικές διεργασίες που πραγματοποιούνται κατά τη λειτουργία τους. Αρχικά περιγράφεται η λειτουργία του SOFC και αναπτύσσονται οι εξισώσεις που συνιστούν το μαθηματικό πρότυπο SOFC. Επίσης, παρουσιάζονται επιλεγμένα μαθηματικά πρότυπα που αναφέρονται στη βιβλιογραφία για την προσομοίωση των διεργασιών που λαμβάνουν χώρα στο SOFC. Στην συνέχεια, περιγράφεται η μέθοδος βελτιστοποίησης που χρησιμοποιείται για την εκτίμηση των παραμέτρων των μαθηματικών προτύπων. Τέλος, παρατίθενται τα αποτελέσματα και τα συμπεράσματα που απορρέουν από την προσομοίωση και την εκτίμηση παραμέτρων καθώς και προτάσεις για μελλοντική έρευνα. / Human impact on the environment, has led the scientific community in research of more efficient and environmentally friendly energy production technologies. In this frame, fuel cell technology has attracted considerable attention. Fuel cells convert the chemical energy stored in a fuel into electrical without being subject to the Carnot cycle limitations. Compared to other types of fuel cells, solid oxide fuel cell (SOFC) stands out mainly due to its high performance. In the present work, parameter estimation of solid oxide fuel cell mathematical prototypes is implemented, in order to analyze the electrochemical processes taking place during SOFC operation. Initially, SOFC performance is described and the SOFC prototype equations are developed. Furthermore, selected mathematical prototypes reported in literature for the simulation of the processes taking place in the SOFC are presented. Then, the simulation method used for the parameter estimation of the mathematical prototypes is described. Finally, simulation results and conclusions derived from parameter estimation as well as suggestions for future work are given.
74

Fantastique et révolte chez Jean Muno et Hugo Raes / Fantastic and Revolt in the Work of Jean Muno and Hugo Raes

Josefson, Åsa 06 March 2010 (has links)
Cette étude est consacrée aux expressions de la thématique de la révolte chez les écrivains belges Jean Muno (1924-1988), francophone, et Hugo Raes (1929-), néerlandophone. Il ne s’agit pas d’une étude comparée de leurs œuvres respectives, une approche exclue par les différences qui les séparent, mais d’une mise en valeur d’une thématique qui relie deux écrivains du même pays et de la même génération, tous deux actifs dans le domaine de la littérature de l’imaginaire. L’objectif est double : le premier est de relever et analyser les différentes composantes de la thématique de la révolte dans leurs textes. Le second est de cerner la particularité de leur fantastique à l’aide d’un modèle élaboré dans la section théorique du présent travail, inspiré par la théorie des prototypes telle qu’elle a été formulée par Eleanor Rosch. / This thesis focuses on the thematic of revolt in the work of the two Belgian writers Jean Muno (1924-1988), French-speaking, and Hugo Raes (1929-), Dutch-speaking. It is not a comparative study of their texts; the differences between them exclude such an approach. The present study highlights a thematic that connects two authors from the same country, of the same generation, both active in the field of fantastic literature. It has a double aim: the analysis of the different components of the thematic of revolt in their work is the first. The second is to define the distinctive features of their fantastic texts with the aid of a model elaborated in the theoretic section of the thesis, inspired by Eleanor Rosch’s prototype theory.
75

Integrating visual feedback and a vision agent into the telemanufacturing environment.

04 June 2008 (has links)
The automated fabrication of a prototype three-dimensional part from a three-dimensional drawing can be regarded as rapid prototyping. There are two basic types of rapid prototyping: subtractive fabrication and additive fabrication. Subtractive fabrication begins with a block of material that is larger than the object to be created and “sculpts” the block into the required prototype three-dimensional part. Additive fabrication continuously adds particles to an object until the desired object is created. Often this process builds a prototype three-dimensional part layer by layer. The prototype three-dimensional parts are created by particular rapid prototyping hardware. Telemanufacturing allows for the remote submission of three-dimensional drawings via a communication medium to the site where the rapid prototyping machine resides. The communication medium for the purposes of this dissertation is the Internet. After the three-dimensional drawing is submitted to the remote site, the rapid prototyping machine proceeds to create the prototype three-dimensional part. The aim of this research is to integrate a visual feedback system into the telemanufacturing environment. The visual feedback system allows a user at a remote location to view the progress of the manufacture of the prototype three-dimensional part in real time. This research also aims to integrate a software agent into the telemanufacturing environment. An agent is loosely defined as “one that acts for another”. The software agent discussed in this dissertation will analyze visual data obtained from the rapid prototyping environment, determine if the prototype three-dimensional part being created contains errors, and take the necessary action. The ultimate goal of this dissertation is to allow the visual analysis of a part as a rapid prototyping machine is creating it. This research allows for two approaches to this “visual analysis”: human analysis, and analysis by a software agent. The “visual analysis” will detect any errors that have occurred during the manufacturing process and ultimately result in the reduction of time and resources to create prototype three dimensional parts using telemanufacturing. / Prof. E.M. Ehlers
76

The need for speed : A study of how a new digital tool can affect B2B relationships

Hellsten, Josefin, Näsström, Johan January 2019 (has links)
The technological development that we have seen in the last decades has resulted in a more digitized business environment and affected industries from an innovative and competitive perspective. The digital transition is an ongoing process and it creates opportunities and challenges for businesses globally. Digital transitions can have consequences for different aspects within a company, from the top management all the way to their customer relations. This study is concentrated on the latter, namely customer relations in a business-to-business context within the sportswear industry. The purpose of this degree project is to develop a deeper understanding about how perceived usefulness of a new digital tool affects the behavioral intention to use it based on a relationship marketing perspective. The study specifically investigates key account managers in a business-to-business context from the sportswear company Athics. By investigating perceived usefulness of 3D Virtual Prototypes by the key account managers’ behavioral intention to use, we managed to explain whether this technology would be accepted or rejected by the managers. None of the key account managers had previous experience with 3D Virtual Prototypes. The degree project had a qualitative method where we interviewed eight key account managers from the product division Athics Footwear through semi-structured interviews. The study takes a deductive approach. The ontological and epistemological stances are interpretivism and constructionism. After reviewing the literature on relationship marketing and technology acceptance model, we formed a conceptual model to get a deeper understanding of their relation to each other. This model was reconstructed once the empirical findings were analysed due to new findings. The revised model contributes to research on relationship marketing and technology acceptance. The findings show that Athics key account managers have a positive attitude towards using 3D Virtual Prototypes and intend to use it once Athics implements this new technology. They believe that 3D Virtual Prototypes can affect relationship strength directly and perceive it as useful in creating long-lasting relationships with their business-to-business customers. However, the study’s result shows that relationship performance will only be affected by sales performance. Implying that 3D Virtual Prototypes can still be perceived as useful but from a different cause. Moreover, the study’s result shows that by implementing 3D virtual prototypes customers will get more involved in the process of developing a shoe. Therefore, we consider customer involvement as a new finding and an important factor in relationship marketing when implementing a new digital tool. The key account managers perceive the digital tool to be more useful towards larger accounts due to their innovative and collaborative side. Smaller accounts are more challenging since they express a more conservative mindset by being less collaborative and perceive innovations as a higher risk.
77

Algorithms for layered manufacturing in image space. / CUHK electronic theses & dissertations collection

January 2013 (has links)
Layered manufacturing plays important role in industry. Conventional pro-cess planning takes polygon soup as input and has high quality requirements on these polygonal model such as no self-intersection, no degenerate polygon et al. A growing number of models, especially for those in complex shape are acquired from reverse engineering. Implicit representation always serves as intermediate representation and ¯nally need to be tesselated into polygonal mesh for layered manufacturing applications. However, the present tessellation techniques have difficulties to provide topologically faithful and self-intersection free polygonal mesh from implicit model. On the other hand, implicit representation are mathematically compact and robust, which is important for presenting complex freeform models. / I develop a robust and efficient approach to directly slicing implicit solids. Different from prior slicing techniques that reconstruct contours on the slicing plane by tracing the topology of intersected line segments, which is actually not robust, I generate contours through a topology guaranteed contour extraction on binary images sampled from given solids and a subsequent contour simplification algorithm which has the topology preserved and the geometric error controlled. The resultant contours are free of self-intersection, topologically faithful to the given r-regular solids and with shape error bounded; therefore, correct objects can be fabricated from them by layered manufacturing. Moreover, since I do not need to generate the tessellated B-rep of given solids, my direct slicing approach is memory efficient - only the binary image and the finest contours on one particular slicing plane need to be stored in-core. My method is general and can be applied to any implicit representations of solids. / Moreover, I also investigate techniques for support generation for layered manufacturing in image space. Region subtraction is a crucial operation for support generation. I develop a robust and reliable region subtraction method on implicit solid slicing. Compared with the conventional approach in which support regioncontours are produced from part slicing contours by polygonal operations, my approach calculates reasonable support region on binary image for each layer. I investigate a conservative growing-swallow technique to remove as much as possible the support material for self-support region while still guarantee the safety of building process. My region subtraction can serve as core technique for many layered manufacturing processes. In my research, I demonstrate region subtraction technique in both Fused Decomposition Modeling(FDM) and Stereolithography(SLA). A region cleaning technique which can reduce topology complexity of calculated support structure region is developed to fulfil specific requirement of FDM. With all the operations involved being discrete on binary image, my approach is more robust compared with the polygonal operations which are based on numerical computation. Moreover, processing on binary image makes my approach highly parallelizable. My self-intersection free contour extraction technique used in direct slicing can also be adopted to extract support structure contour on binary image if necessary. / Huang, Pu. / "October 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 80-84). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract --- p.i / Chinese Abstract --- p.iii / Acknowledgements --- p.iv / List of Figures --- p.vii / List of Tables --- p.ix / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Contribution --- p.4 / Chapter 1.3 --- Organization --- p.5 / Chapter 2 --- Literature Review --- p.7 / Chapter 2.1 --- Direct Slicing on Implicit Solid --- p.7 / Chapter 2.2 --- Slicing based Support Generation --- p.9 / Chapter 3 --- Problem Definition --- p.10 / Chapter 4 --- Topologically Faithful Slicing Contour Generation --- p.12 / Chapter 4.1 --- Introduction --- p.12 / Chapter 4.2 --- Sampling and Contour Generation --- p.15 / Chapter 4.2.1 --- Sampling --- p.16 / Chapter 4.2.2 --- Topologically faithful contouring --- p.17 / Chapter 4.2.3 --- r-Regularity and Accuracy in Layered Manufacturing --- p.19 / Chapter 4.3 --- Constrained Smoothing --- p.20 / Chapter 4.4 --- Contour Simplification --- p.24 / Chapter 4.4.1 --- Variational segmentation --- p.25 / Chapter 4.4.2 --- Topology and distortion verification --- p.27 / Chapter 4.4.3 --- Hausdorff Error Analysis --- p.31 / Chapter 4.5 --- Results and Discussion --- p.33 / Chapter 5 --- Reliable and Robust Region Subtraction for Support Generation --- p.43 / Chapter 5.1 --- Introduction --- p.43 / Chapter 5.2 --- Preliminary --- p.46 / Chapter 5.3 --- Region Subtraction --- p.48 / Chapter 5.3.1 --- Binary Image Grid-width and Self-support Feature Threshold --- p.48 / Chapter 5.3.2 --- Conservative Growing-swallow Method --- p.50 / Chapter 5.4 --- Region Cleaning Technique for FDM --- p.53 / Chapter 5.5 --- Anchor Support Generation for SLA --- p.57 / Chapter 5.6 --- Result and Discussion --- p.60 / Chapter 6 --- Conclusion --- p.71 / Chapter 6.1 --- Summary and Discussion --- p.71 / Chapter 6.2 --- Future Work --- p.73 / Chapter A --- Inconsistent Contouring Problem Analysis --- p.76 / Bibliography --- p.80
78

Avaliação de revestimento anticorrosivo orgânico aplicado em válvulas do tipo esfera para operações subsea

Faccio, Mateus January 2017 (has links)
Motivada pelos inúmeros desafios relacionados à exploração de petróleo na região do pré-sal, onde o ambiente agressivo aliado com a grande profundidade são fatores sempre presentes, a busca por materiais alternativos para aplicações em válvulas ganhou destaque. As válvulas subsea, essenciais para projetos de exploração nestas áreas são consideradas um desafio ainda maior. Dessa maneira, estudos e ensaios de desempenho em revestimentos anticorrosivos orgânicos nesse ambiente tornam-se necessários. O objetivo deste trabalho é avaliar a resistência à corrosão e ao desgaste do revestimento anticorrosivo orgânico ECTFE (Halar®) para a aplicação em válvulas industriais do tipo esfera para operações subsea, através da realização de ensaios em corpos de prova e em protótipos, perante as condições simuladas do ambiente agressivo na qual deverão operar em conformidade com o programa de qualificação do revestimento D-SMA/ING/SPF/TCNA-14-00047. Para a realização dos ensaios, foram projetados sistemas de tubulações fechadas (loopings), nos quais os protótipos foram instalados. Os parâmetros de testes estabelecidos, assim como os dados monitorados pelos sensores instalados, foram coletados durante todo o período de teste. Os ensaios definidos para a avaliação do revestimento orgânico em protótipos foram: ciclos de pressão, circulação sob vazão, circulação com água arenosa e ensaios de corrosão com e sem defeito imposto no revestimento. Complementarmente, corpos de prova em escala reduzida foram submetidos a ensaio de adesão e de fadiga. Os resultados obtidos foram conclusivos e o revestimento mostrou-se resistente às condições impostas aos protótipos, uma vez que não foram detectadas descontinuidades consideradas relevantes segundo os critérios de aceitação pré-estabelecidos em procedimento. / The search for alternative materials for applications in valves has been highlighted motivated by the numerous challenges related to oil and gas in the pre-salt region, where the aggressive environment combined with great depth are always present factors. The subsea valves, essential for exploration projects in these areas, are considered an even bigger challenge, thus, studies and performance tests on organic anti-corrosion coatings in this environment become necessary. The purpose of this study is to evaluate resistance to corrosion and wear of organic anti-corrosion coating ECTFE (Halar®) for application of industrial ball valves for subsea operations, by conducting tests on specimens and prototypes, under simulated harsh environment conditions in which they should operate in accordance with the coating qualification program D-SMA / ING / SPF / TCNA-14-00047. Closed pipes systems are designed (loops) for the carrying out of the tests, in which the prototypes were installed. The set of test parameters as well as the monitored data by installed sensors were collected during the entire test period. The defined tests for the evaluation of the organic coating in prototypes were: pressure cycles, flow rate circulation, circulation in soapy water and corrosion tests with and without defects imposed in the coating. In addition, reduced specimens were submitted to adhesion and fatigue tests. The results were conclusive and the coating was resistant to the imposed conditions on prototypes, since relevant discontinuities were not detected according to pre-established acceptance criteria for the procedure.
79

Méthodes d'apprentissage pour la classification multi label / Learning methods for multi-label classification

Kanj, Sawsan 06 May 2013 (has links)
La classification multi-label est une extension de la classification traditionnelle dans laquelle les classes ne sont pas mutuellement exclusives, chaque individu pouvant appartenir à plusieurs classes simultanément. Ce type de classification est requis par un grand nombre d’applications actuelles telles que la classification d’images et l’annotation de vidéos. Le principal objectif de cette thèse est la proposition de nouvelles méthodes pour répondre au problème de classification multi-label. La première partie de cette thèse s’intéresse au problème d’apprentissage multi-label dans le cadre des fonctions de croyance. Nous développons une méthode capable de tenir compte des corrélations entre les différentes classes et de classer les individus en utilisant le formalisme de représentation de l’incertitude pour les variables multi-valuées. La deuxième partie aborde le problème de l’édition des bases d’apprentissage pour la classification multi-label. Nous proposons un algorithme basé sur l’approche des k-plus proches voisins qui permet de détecter les exemples erronés dans l’ensemble d’apprentissage. Des expérimentations menées sur des jeux de données synthétiques et réelles montrent l’intérêt des approches étudiées. / Multi-label classification is an extension of traditional single-label classification, where classes are not mutually exclusive, and each example can be assigned by several classes simultaneously . It is encountered in various modern applications such as scene classification and video annotation. the main objective of this thesis is the development of new techniques to adress the problem of multi-label classification that achieves promising classification performance. the first part of this manuscript studies the problem of multi-label classification in the context of the theory of belief functions. We propose a multi-label learning method that is able to take into account relationships between labels ant to classify new instances using the formalism of representation of uncertainty for set-valued variables. The second part deals withe the problem of prototype selection in the framework of multi-label learning. We propose an editing algorithm based on the k-nearest neighbor rule in order to purify training dataset and improve the performances of multi-label classification algorithms. Experimental results on synthetic and real-world datasets show the effectiveness of our approaches.
80

Quelques fonctionnalités de bases de données avancées

Nguyen, Gia Toan 19 June 1986 (has links) (PDF)
On utilise une méthode de représentation de l'information basée sur la logique des prédicats du premier ordre pour enrichir la représentation sémantique des données qui peuvent être stockées dans un ensemble de bases de données reparties. On définit ensuite une méthode originale d'évaluation de questions sur des données distribuées basée sur une décomposition dynamique des opérations. On propose enfin une nouvelle approche pour le contrôle des contraintes sémantiques dans une base de données. Elle est basée sur la notion de prototypes logiques d'objets formant un échantillon de la base de données.

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