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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.
291

Modélisation et Optimisation d'un Générateur Synchrone à Double Excitation de Forte Puissance

Ammar, Aymen 28 June 2013 (has links) (PDF)
Alliant flexibilité de contrôle et bon rendement, les Machines Synchrone à Double Excitation (MSDE) sont de plus en plus investiguées pour diverses applications de petites et moyennes puissances et rarement pour des applications de fortes puissances. Cette thèse a pour objectif l'étude d'un Générateur Synchrone à Double Excitation (GSDE) de forte puissance. Un modèle de comportement a été établi. Des méthodes analytiques et semi-analytiques ont été utilisées pour la modélisation multi-physique de la machine. Ce modèle a été validé, dans un premier temps, par comparaison aux résultats d'un modèle éléments finis.Comparé à un Générateur Synchrone à Pôles Saillants (GSPS), le GSDE offre des solutions plus intéressantes énergétiquement et économiquement, que ce soit en fonctionnement à vitesse constante ou à vitesse variable. Dans le cadre d'un fonctionnement en générateur éolien, l'augmentation du nombre d'encoche par pôle et par phase et l'augmentation de la fréquence d'alimentation contribuent à l'amélioration des performances de la GSDE. Cependant il faudrait tenir compte des impacts sur l'électronique de puissance et le multiplicateur mécanique. En plus, la distribution de Weibull et le bon choix de la plage utile de variation de la vitesse du vent, jouent un rôle important sur le dimensionnement optimal du générateur éolien.Un prototype de GSDE d'une puissance d'1MVA a été dimensionné, optimisé et fabriqué. Tout d'abord, le prototype a servi à la validation du modèle multi-physique. En plus la réalisation des essais sur deux étapes (avant et après le collage des aimants permanents) a montré l'apport énergétique du GSDE par rapport au GSPS
292

Reikalavimų specifikavimo šablonų pagrindu analizė ir programinis prototipas / Analysis of requirements specification using templates and programme prototype

Zinkevičius, Egidijus 04 March 2009 (has links)
Reikalavimų inžinerija yra bene svarbiausias etapas informacinės sistemos kūrime. Tik tikslus reikalavimų specifikavimo proceso valdymas leis sėkmingai projektuoti, realizuoti ir įdiegti informacines sistemas kompiuterizuojamose srityse. Dažnai neefektyvus reikalavimų rinkimo procesas tampa projekto nesėkmės ar programinės įrangos defekto pagrindu. Be to, aptiktų netikslumų pašalinimo kaina kyla eksponentiškai, kai jie atrandami vėlyvosiose projekto stadijose. Todėl įmonės ar asmenys, siekiantys pagerinti projekto kokybę ir produktyvumą, turėtų ypatingai atkreipti dėmesį į reikalavimų valdymo procesą. Pastebėta, jog reikalavimų specifikavimo procesas vis labiau kompiuterizuojamas, o reikalavimų valdymo įrankių bei šablonų naudojimas gerina reikalavimų specifikacijos ir būsimo produkto kokybę. Šis magistrinis darbas yra skirtas reikalavimų specifikavimo šablonų pagrindu eksperimentiniam tyrimui ir jo vertinimui. / The usage of computers takes more important place in our modern life. It was noticed that more and more enterprises use requirement management tools and specification templates to increase quality of requirement specification and projects. Very often ineffective requirements-gathering processes are the source of project failures and software defects. In addition, the cost of fixing defects rises exponentially as their discovery occurs later in the development process. However, a solid requirements process is fundamental to an effective overall process, and companies seeking increased quality and productivity should start with the requirements process. The intention of this work is to make the experimental research of requirements specification using templates and evaluate it.
293

Swedish Dimensional Adjectives / Svenska dimensionsadjektiv

Vogel, Anna January 2004 (has links)
The purpose of this study is to give a thorough and detailed account and analysis of the semantics of twelve Swedish dimensional adjectives: hög ’high/tall’, låg ’low’, bred ’broad/wide’, smal ’narrow’ vid ’broad’, trång ’narrow’, tjock ’thick’, tunn ’thin’, djup ’deep’, grund ’narrow’, lång ’long’ and kort ’short’. Focus has been placed on their spatial, non-metaphorical sense. The study was written within the framework of cognitive linguistics, where lexical definitions may be given in terms of prototypical and peripheral uses. Four sources of data have been considered: a corpus, consisting of contemporary fiction, an elicitation test, designed for the purpose, dictionary articles on the pertinent adjectives, and the author's own linguistic intuition as a native speaker. The methodology has involved categorisation of combinations of adjective and noun, based upon three major themes: orientation, function, and shape. In order to determine prototypical uses, precedence has been given to the outcome of the elicitation test over the corpus search. For both sources, frequency has played an important part. The ranking of senses as stated in the dictionary articles has also been considered. The results indicate that the dimensional adjectives differ quite markedly from each other, as opposed to a structural view where the adjectives traditionally have been regarded as forming a neat patchwork. Adjectives overlap each other for some uses (högt gräs ’high grass’, långt gräs ’long grass’ and even djupt gräs ’deep grass’), while there are also situations in which no dimensional adjective can describe an object. Furthermore, adjectives forming pairs, such as djup – grund ’deep – shallow’, do not exhibit full antonymy, despite the fact that dimensional adjectives are traditionally cited as examples par excellence concerning antonymy.
294

Elektros tinklo valdymo laboratorinio stendo prototipas / Laboratory equipment prototype for electrical network control

Jučas, Tomas 02 July 2012 (has links)
Parengtas bakalauro baigiamasis darbas yra skirtas suprojektuoti ir pagaminti automatinio rezervo įjungimo skydo prototipą, kurį būtų galima naudoti laboratoriniams darbams universitete.Šio darbo paskirtis yra papildyti elektros aparatų discipliną dar vienu, dažnai sutinkamu ir naudojamu visame pasaulyje stendu, paaiškinant jo veikimo principą, galimybes. Darbe aiškiai yra išdėstomos visos stendo dalys, stendui keliami reikalavimai, parodomos principinė ir valdymo schemos, paaiškinamas detalus veikimas, stendo valdiklio programos algoritmas. Taip pat supažindinama su Lucas-neulle mokomuoju dviejų atskirų tiekimo linijų stendu, parodant visas jo sudedamąsias dalis ir jas trumpai paaiškinant. / ATS helps to avoid serious problems in healthcare facilities for example by the same time when surgery is being held to save human lives and power supply interference occurs, it safely automatically switches power supply mains with no effect to the user. In industry it helps to avoid any power supply problems which every single of them could lead to destruction of expensive machinery or even harm people. Considering problems occurring in power supply lines, this was a great inspiration to produce automatic transfer switch prototype as my Bachelors degree thesis. Since Electrical Engineering Department had no real ATS system prototype before, it will surely supply existing basis and will help students to gain useful experience. Furthermore, all the details about ATS are expounded and will lead to full understanding of the system.
295

MULTIPLE CHANNEL COHERENT AMPLITUDE MODULATED (AM) TIME DIVISION MULTIPLEXING (TDM) SOFTWARE DEFINED RADIO (SDR) RECEIVER

Alluri, Veerendra Bhargav 01 January 2008 (has links)
It is often required in communication and navigation systems to be able to receive signals from multiple stations simultaneously. A common practice to do this is to use multiple hardware resources; a different set of resources for each station. In this thesis, a Coherent Amplitude Modulated (AM) receiver system was developed based on Software Defined Radio (SDR) technology enabling reception of multiple signals using hardware resources needed only for one station. The receiver system architecture employs Time Division Multiplexing (TDM) to share the single hardware resource among multiple streams of data. The architecture is designed so that it can be minimally modified to support any number of stations. The Verilog Hardware Description Language (HDL) was used to capture the receiver system architecture and design. The design and architecture are initially validated using HDL post-synthesis and post-implementation simulation. In addition, the receiver system architecture and design were implemented to a Xilinx Field Programmable Gate Array (FPGA) technology prototyping board for experimental testing and final validation.
296

Conception et intégration de microsystèmes sur un cylindre pour la mesure de ses déformations : application à un outil du domaine de la santé

Yang, Wenbin 24 November 2011 (has links) (PDF)
L'objectif de cette thèse est de développer un cylindre instrumenté pour mesurer sa déflexion dans les applications médicales. Deux types de matériaux sont utilisés pour le cylindre : l'acier inoxydable et le NiTi. Des microjauges sont réparties le long du cylindre pour mesurer en temps réel sa déformation, permettant ainsi de guider le cylindre à sa destination envisagée dans un geste chirurgical. Plusieurs approches pour la mesure de déformation sont présentées et comparées, et la mesure de déformation par les microjauges piézorésistives semiconductrices intégrées sur le cylindre paraît la méthode optimale en tenant compte de la sensibilité, la compatibilité biomédicale et la faisabilité en microfabrication. Des analyses théoriques et par méthode d'éléments finis sont effectués pour analyser le comportement mécanique du cylindre en flexion mais aussi pour positionner et dimensionner les microjauges piézorésistives sur le cylindre. Un premier prototype a été réalisé et caractérisé pour vérifier la fonctionnalité de notre système.La réalisation des microjauges sur les cylindres se déroule par la microfabrication en salle blanche. Le germanium est utilisé comme le matériau piézorésistif. A cause de la spécificité géométrique des cylindres en tant que le substrat de la microfabrication, de nombreuses modifications sont apportées au procédé de fabrication 'standard' pour le dépôt et l'usinage des matériaux en surface du substrat métallique courbe. Le résultat de microfabrication est présenté, ainsi que l'analyse et les améliorations éventuelles du procédé actuel.
297

Emotion lexicon in the Sepedi, Xitsonga and Tshivenda language groups in South Africa : the impact of culture on emotion / T. Nicholls

Nicholls, Tanja January 2008 (has links)
Thesis (M.A. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2008.
298

Emotion lexicon in the Sepedi, Xitsonga and Tshivenda language groups in South Africa : the impact of culture on emotion / T. Nicholls

Nicholls, Tanja January 2008 (has links)
Thesis (M.A. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2008.
299

Leadership Style Of Turkish Middle Level Managers In Private Sector And Its Relationship With Subordinate Performance, Satisfaction, And Commitment

Ozmen, Ipek Nursel 01 December 2005 (has links) (PDF)
The main purpose of the present study was to examine the leadership styles of Turkish middle-level managers and leadership prototypes of Turkish employees in terms of task-oriented and people-oriented behaviours. The secondary purpose was to investigate the effects of incongruence between actual and ideal manager perceptions on three important work outcomes: performance (task and contextual performance), job satisfaction, and organizational commitment (affective, continuance, and normative commitment). A total of 320 people working in a wide range of organizations (71 managers and 239 employees) filled out the questionnaire. Employees rated their actual managers&rsquo / leadership style and also their ideal manager&rsquo / s leadership style (i.e., leader prototype) in the same questionnaire, while the managers rated their own leadership style as well as their leadership style as perceived by their subordinates. Additionally, supervisory-rated performance and self-rated job satisfaction and organizational commitment levels of employees were obtained. Results indicated that self-reported leadership styles of Turkish managers were consisting of more people-oriented behaviours than task-oriented behaviours. On the contrary, employees perceived their managers as being more task-oriented than people-oriented. Ideal leadership style for the employees were comprised of higher levels of both task- and people-oriented behaviours than their actual managers. Incongruence between the actual and ideal manager perceptions of employees predicted job satisfaction levels of the employees only. The results are discussed together with the implications, strengths and limitations of the study. Some suggestions for future research are made.
300

Evaluation of loggerhead sea turtle carapace properties and prototype biomimetic carapace fabrication

Hodges, Justin E. 11 November 2008 (has links)
The research presented in this study has been conducted in an effort to aid in the creation of a biomimetic shell that may be employed in full-scale field experiments to determine the efficacy of mitigation options to limit loggerhead mortality in boat strike incidents. The objectives of this research include the development of experimental testing procedures for the material characterization of the loggerhead carapace, and the design, fabrication, and evaluation of an artificial prototype carapace. A photographic database of wounded sea turtles in Georgia was evaluated in order to determine the primary sources of loggerhead collision injuries and the most common regions of the carapace damaged in boat strike incidents. Skeg impact was found to be the most common source of injury, with a frequency of 44%. In addition, 74% of the sea turtles reviewed sustained injuries to the center third of their carapace length, indicating this region as the most probable impact location. Material testing procedures were developed for evaluating the material properties of the loggerhead carapace. This was followed by the material testing of three loggerhead shells for the purpose of determining localized mechanical properties. Samples were harvested from the shells in a manner designed to identify potential variations in properties due the location and orientation of the coupons within the carapace. Each coupon was subjected to axial tension or three-point bending. Specialized tabs were designed for tension testing in order to accommodate the coupon's irregular geometry and minimize curvature-induced moments. The tensile test results indicated that the longitudinal and transverse properties of the loggerhead carapace were similar. The tensile strength, elongation at failure, and modulus of elasticity were determined to have percent variations of 12.2%, 10.7%, and 10.1% respectively. In contrast, the three-point bending test results indicated that the modulus of rupture and flexural modulus for the transverse samples were approximately four times greater than those of the longitudinal samples. This variation may be attributed to regions of weak tissue running transversely through the carapace. The results of the material testing were utilized in the design of two prototype composite shells. The prototypes were successful in simulating the strain at failure and force per unit width to within 10% of the loggerhead carapace. The resulting procedure may be used to create artificial shells suitable for prototype scale tests in natural environments. In addition, the material testing methods developed for this investigation may offer insight into procedures for evaluating alternate forms of rigid or curved biological specimens.

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