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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.
171

Offset Surface Light Fields

Ang, Jason January 2003 (has links)
For producing realistic images, reflection is an important visual effect. Reflections of the environment are important not only for highly reflective objects, such as mirrors, but also for more common objects such as brushed metals and glossy plastics. Generating these reflections accurately at real-time rates for interactive applications, however, is a difficult problem. Previous works in this area have made assumptions that sacrifice accuracy in order to preserve interactivity. I will present an algorithm that tries to handle reflection accurately in the general case for real-time rendering. The algorithm uses a database of prerendered environment maps to render both the original object itself and an additional bidirectional reflection distribution function (BRDF). The algorithm performs image-based rendering in reflection space in order to achieve accurate results. It also uses graphics processing unit (GPU) features to accelerate rendering.
172

Hardware bidirectional real time motion estimator on a Xilinx Virtex II Pro FPGA

Iqbal, Rashid January 2006 (has links)
This thesis describes the implementation of a real-time, full search, 16x16 bidirectional motion estimation at 24 frames per second with the record performance of 155 Gop/s (1538 ops/pixel) at a high clock rate of 125 MHz. The core of bidirectional motion estimation uses close to 100% FPGA resources with 7 Gbit/s bandwidth to external memory. The architecture allows extremely controlled, macro level floor-planning with parameterized block size, image size, placement coordinates and data words length. The FPGA chip is part of the board that was developed at the Institute of Computer & Communication Networking Engineering, Technical University Braunschweig Germany, in collaboration with Grass Valley Germany in the FlexFilm research project. The goal of the project was to develop hardware and programming methodologies for real-time digital film image processing. Motion estimation core uses FlexWAFE reconfigurable architecture where FPGAs are configured using macro components that consist of weakly programmable address generation units and data stream processing units. Bidirectional motion estimation uses two cores of motion estimation engine (MeEngine) forming main data processing unit for backward and forward motion vectors. The building block of the core of motion estimation is an RPM-macro which represents one processing element and performs 10-bit difference, a comparison, and 19-bit accumulation on the input pixel streams. In order to maximize the throughput between elements, the processing element is replicated and precisely placed side-by-side by using four hierarchal levels, where each level is a very compact entity with its own local control and placement methodology. The achieved speed was further improved by regularly inserting pipeline stages in the processing chain.
173

Offset Surface Light Fields

Ang, Jason January 2003 (has links)
For producing realistic images, reflection is an important visual effect. Reflections of the environment are important not only for highly reflective objects, such as mirrors, but also for more common objects such as brushed metals and glossy plastics. Generating these reflections accurately at real-time rates for interactive applications, however, is a difficult problem. Previous works in this area have made assumptions that sacrifice accuracy in order to preserve interactivity. I will present an algorithm that tries to handle reflection accurately in the general case for real-time rendering. The algorithm uses a database of prerendered environment maps to render both the original object itself and an additional bidirectional reflection distribution function (BRDF). The algorithm performs image-based rendering in reflection space in order to achieve accurate results. It also uses graphics processing unit (GPU) features to accelerate rendering.
174

Έλεγχος της μίξης κυμάτων και της δημιουργίας αργού φωτός υπό συνθήκες ηλεκτρομαγνητικά επαγώμενης διαφάνειας και ενίσχυσης χωρίς αντιστροφή πληθυσμού σε μεταλλικούς ατμούς

Πένταρης, Διονύσιος 06 September 2010 (has links)
Στη παρούσα διατριβή μελετούμε την αλληλεπίδραση ατόμων αλκαλίων (νατρίου-Na και καλίου-K) με σύμφωνη πηγή ακτινοβολίας (laser). Συγκεκριμένα παρουσιάζουμε: i) Την επίδραση της καταστρεπτικής κβαντικής συμβολής (destructive quantum interference), η οποία εμφανίζεται στη διαδρομή-1, του ατομικού K υπό nsec διφωτονική διέγερση. Η καταστρεπτική κβαντική συμβολή οδηγεί στη γραμμική απόκριση των εσωτερικά παραγόμενων εντάσεων των ακτινοβολιών στις μεταβάσεις των παραγόμενων πεδίων της διαδρομής-1. Το φαινόμενο αυτό μελετάται για διάφορες τιμές των παραμέτρων: της μέγιστης έντασης της διεγείρουσας ακτινοβολίας του laser, του διφωτονικού αποσυντονισμού, της ατομικής πυκνότητας και του μήκους διάδοσης των ακτινοβολιών, όταν οι δύο από τις τρείς αυτές παραμέτρους παραμένουν σταθερές. Επίσης, μελετούμε τις προυποθέσεις του κορεσμού της διαδρομής-1 για ισχυρότερη ένταση του εξωτερικού πεδίου laser και κατόπιν δείχνουμε ότι η διαδρομή-2, εμφανίζεται, έχοντας πρώτα κορεσθεί η διαδρομή-1, στις μικρές ατομικές πυκνότητες. Επιπρόσθετα, παρουσιάζουμε τις προυποθέσεις επαγωγής ενός είδους ατομικής μνήμης (optical free induction memory) όταν ο παλμός laser υποστεί απότομη πτώση στο μέγιστο του (truncated pulse). ii) Τις συνθήκες εκείνες οι οποίες ευθύνονται για την εμφάνιση αξονικής ή/και κωνικής εκπομπής της διαδρομής-1, και διαδρομής-2, αντίστοιχα, για διάφορες ατομικές πυκνότητες, υπό fsec διφωτονική διέγερση του ατομικού K. iii) Την παραγωγή ακτινοβολιών από σύμφωνη παραμετρική μίξη (parametric four-wave mixing) ή και μερικώς σύμφωνο μηχανισμό όπως η ενισχυμένη αυθόρμητη εκπομπή (amplified spontaneous emission) ή υπέρ σκέδαση- Raman (stimulated hyper-Raman scattering), όταν το nsec πεδίο laser διεγείρει με δύο φωτόνια την μετάβαση 4S1/2-6S1/2, καθώς και την μετάβαση 4S1/2-7S1/2, αντίστοιχα. Εστιάζουμε κατά μείζονα λόγο τη μελέτη μας στη διαδρομή-2, στήν μονόδρομη (unidirectional) και στήν αμφίδρομη (bidirectional) διάδοση της ακτινοβολίας του πεδίου laser. iv) Την γέννεση της κωνικής τρίτης αρμονικής (conical third harmonic generation-THG) σε μεταλλικούς ατμούς Na και K υπό fsec διέγερση. Στη περίπτωση του Na (μέσο με κανονική διασπορά) βρίσκουμε ότι η χαρακτηριστική δακτυλοειδή δομή του κώνου της τρίτης αρμονικής οφείλεται στήν επίδραση κυρίως του τανυστικού όρου πέμπτης τάξης ο οποίος σχετίζεται με την μίξη έξι κυμάτων. Ακόμα, δείχνουμε, ότι στη περίπτωση του K (μέσο με αρνητική διασπορά) η εκπομπή μακρινού πεδίου (far field emission) της κωνικής τρίτης αρμονικής, παρουσιάζει ορισμένες διαφοροποιήσεις σε σχέση με αυτή του Na. Το όλο φαινόμενο αντιμετωπίζεται φαινομενολογικά. / In the doctorate dissertation is studied the effect of the wave mixing of laser light with the internally generated fields of the alkali vapors, such as the sodium (Na) and the potassium (K) respectively. Specifically it was studied: ι) The numerical simulation of the four-level system, when a two-photon nsec field excites the transition 4S1/2-6S1/2 of potassium atom. It is shown that the destructive quantum interference is responsible for the reduction of the non-linearity of path-1, in which, the parameters of the system, such as the two-photon detuning, the atomic density and the laser maximum intensity, play an important role. Moreover the saturation of the path-1 has as a consequence the passage of the energy to the atomic path-2, which activates later than the path-1, in low atomic density of atomic K. A truncated excitation pulse is able to induced phenomena of atomic memory in which the providing excitation intensity is able to be stored in the system. The optical free induction memory (OFIM) is observed in the truncated nsec excitation of the transition 4S1/2-6S1/2. This type of atomic memory is studied via the evolution of the density matrix element s12, for specific selection of the two-photon detuning. ii) The conditions which are responsible for the axial or/and conical emission of radiation of path-1 and of path-2, respectively under the fsec two-photon excitation respectively. iii) The production of coherent (parametric four-wave mixing) or/and partially coherent (amplified spontaneous emission or stimulated hyper-Raman scattering) radiation when the nsec laser field excites with two-photons the transition 4S1/2-6S1/2, and the transition 4S1/2-7S1/2, of atomic potassium respectively. It is also studied the emissions of the path-2 in the unidirectional and the bidirectional propagation (counter-propagation) of the laser field in the nsec 4S1/2-6S1/2 two-photon excitation. iv) The conical third harmonic generation (THG) in Na and K vapor under the fsec excitation. It is proved that the third harmonic generation of Na, (normally dispersive medium), in the laser wavelength range of 1770-2200 nm, is mainly a result of six-wave mixing. The fifth order tensor term dominates against the third order term, (which is connected with the four-wave mixing process), as it is shown theoretically. In the case of Κ vapor (negative dispersion medium), in the laser wavelength range of 1200-2180 nm, the observed conical emission appears similarities and dissimilarities with the Na one respectively. The THG generation of Κ interpreted in a phenomenological way.
175

Alignement paramétrique d’images : proposition d’un formalisme unifié et prise en compte du bruit pour le suivi d’objets

Authesserre, Jean-baptiste 02 December 2010 (has links)
L’alignement d’images paramétrique a de nombreuses applications pour la réalité augmentée, la compression vidéo ou encore le suivi d’objets. Dans cette thèse, nous nous intéressons notamment aux techniques de recalage d’images (template matching) reposant sur l’optimisation locale d’une fonctionnelle d’erreur. Ces approches ont conduit ces dernières années à de nombreux algorithmes efficaces pour le suivi d’objets. Cependant, les performances de ces algorithmes ont été peu étudiées lorsque les images sont dégradées par un bruit important comme c’est le cas, par exemple, pour des captures réalisées dans des conditions de faible luminosité. Dans cette thèse, nous proposons un nouveau formalisme, appelé formalisme bidirectionnel, qui unifie plusieurs approches de l’état de l’art. Ce formalisme est utilisé dans un premier temps pour porter un éclairage nouveau sur un grand nombre d’approches de la littérature et en particulier sur l’algorithme ESM (Efficient Second-order Minimization). Nous proposons ensuite une étude théorique approfondie de l’influence du bruit sur le processus d’alignement. Cette étude conduit à la définition de deux nouvelles familles d’algorithmes, les approches ACL (Asymmetric Composition on Lie Groups) et BCL (Bidirectional Composition on Lie Groups) qui permettent d’améliorer les performances en présence de niveaux de bruit asymétriques (Rapport Signal sur Bruit différent dans les images). L’ensemble des approches introduites sont validées sur des données synthétiques et sur des données réelles capturées dans des conditions de faible luminosité. / Parametric image alignment is a fundamental task of many vision applications such as object tracking, image mosaicking, video compression and augmented reality. To recover the motion parameters, direct image alignment works by optimizing a pixel-based difference measure between a moving image and a fixed-image called template. In the last decade, many efficient algorithms have been proposed for parametric object tracking. However, those approaches have not been evaluated for aligning images of low SNR (Signal to Noise ratio) such as images captured in low-light conditions. In this thesis, we propose a new formulation of image alignment called Bidirectional Framework for unifying existing state of the art algorithms. First, this framework allows us to produce new insights on existing approaches and in particular on the ESM (Efficient Second-order Minimization) algorithm. Subsequently, we provide a theoretical analysis of image noise on the alignment process. This yields the definition of two new approaches : the ACL (Asymmetric Composition on Lie Groups) algorithm and the BCL (Bidirectional Composition on Lie Groups) algorithm, which outperform existing approaches in presence of images of different SNR. Finally, experiments on synthetic and real images captured under low-light conditions allow to evaluate the new and existing approaches under various noise conditions.
176

Features of the Electric Fields Generated by Lightning with Special Attention to Positive Ground Flashes

Johari, Dalina January 2017 (has links)
This thesis focuses on the main processes in positive ground flashes and the distant lightning environment for both positive and negative ground flashes. It presents the characteristics of the preliminary breakdown pulses (PBPs), the characteristics of the electric field pulses observed during leader propagation, and the characteristics of the electric fields produced by the first and the subsequent return strokes. It also features the observations of distant positive and negative ground flashes at distances up to 1000 km. The results were based on electric field measurements conducted remotely during summer thunderstorms in Sweden in 2014. We found that the majority of the positive ground flashes were preceded by PBPs. Some were preceded by more than one PBP train, and the parameter values for the subsequent PBP trains were found to be smaller than the values for the first PBP train. Three types of PBPs were also identified. The results suggest that the PBPs in positive ground flashes during summer thunderstorms in Sweden are weak, and the inverted dipole charge cloud configuration is consistent with our observation. A small percentage of these positive ground flashes were observed to be preceded by pronounced leader pulses. The presence of these pulses suggests that the leaders propagate in a stepped manner. We inferred that these pulses were due to the upward-connecting negative leader since their characteristics were similar to those of a negative stepped leader. On the basis of the leader pulses’ time of initiation and the average speed of the leader, we estimated the distance travelled by the leader. One case of positive return stroke preceded by negative leader pulses was also observed, and the occurrence of these pulses was the first in positive ground flashes to be reported. The majority of these positive ground flashes were found to be single-stroke. Comparison between the first and the subsequent return strokes showed that the average durations of the subsequent stroke parameters were smaller than that of the first strokes. The distances reported by the lightning location system suggest that the subsequent strokes probably created new terminations to ground. Two possible reasons were given to explain the reason for the shorter duration of the subsequent return strokes parameters compared to the first strokes. Finally, observations of distant positive and negative ground flashes showed that the electric field waveforms have a typical shape, like a distorted ‘W’ (or distorted ‘M’ for negative ground flashes) followed by small oscillations. These small oscillations were more pronounced in negative ground flashes, especially at a greater distance. The heights of the ionospheric reflections estimated for both ground flashes were found to likely correspond to a D-layer of the ionosphere. Two possible reasons were suggested for the small oscillations observed in the waveforms.
177

Gestion énergétique optimisée pour un bâtiment intelligent multi-sources multi-charges : différents principes de validations / Optimized Energy Management for an intelligent building : different principles of validation

Badreddine, Rim 06 July 2012 (has links)
Le bâtiment est un noeud énergétique important et un support idéal pour développer etanalyser les effets d’un système de gestion optimisée d’énergie (SGEB) tant son impactpotentiel sur la demande énergétique globale est important. Cependant, pour que ces objectifssoient atteints, plusieurs verrous doivent être levés. Au-delà des problématiques liées àl’architecture de distribution, aux modèles (y compris ceux relatifs au comportement desusagers), aux outils de dimensionnement, à la formalisation des paramètres, contraintes etcritères, aux systèmes de production et aux modes de connexions au réseau de distribution, lesproblèmes liés à la mise en oeuvre d’un outil de gestion décentralisée et à sa validation sontcentraux centrale. Ces travaux s’inscrivent directement dans cette optique. Ils portent enparticulier sur l’élaboration de modèles énergétiques, de stratégies de gestion d’énergie dansune configuration multi-sources et multi-charges et surtout de mise en oeuvre de méthodes etd’outils de validation au travers de bancs tests variés où certains composants peuvent êtreréels.Ce travail analyse le gestionnaire énergétique « G-homeTech » comprenant plusieursfonctionnalités de gestion testées sur des bancs d’essai virtuels et hybrides qui permettent decombiner à la fois des composants matériels et logiciels dans les simulations. Cela a permisd'insérer des actionneurs communicants pour tester leur pertinence. Les validations menéesmontrent que le gestionnaire énergétique permet l'effacement de pointes de consommation etdes économies sur la facture énergétique globale tout en respectant les contraintes techniqueset réglementaires.Les évènements prédits ne sont pas toujours ceux qui se produisent. Nous avons alorssimulé de telles situations. La radiation solaire et la consommation totale des services noncontrôlables sont différentes de celles prédites. Cette différence a conduit à des dépassementsde puissance électrique souscrite qui a activé le mécanisme de gestion réactive du gestionnaireénergétique. Des ordres de délestage sont alors dynamiquement envoyés à certainséquipements. Ces ordres alimentent directement les modèles des équipements électriques.Selon les importances relatives données au coût et au confort, nous avons montré que legestionnaire énergétique permet de faire des économies substantielles en évitant lesconsommations durant les pics de prix et évitant les dépassements de souscription pareffacement, par modulation du fonctionnement des systèmes de chauffage et par décalage defonctionnement des services temporaires dans les périodes plus intéressante énergétiquement. / The building is an important energy node and an ideal support to develop and analyzethe effects of an Energy Management System (EMS). Because of its potential impact, such amanagement of global energy demand is important. However, to achieve these goals, severallocks must be removed. Beyond issues related to the distribution architecture, to models(including those relating to user behavior), sizing tools, the formalization of parameters,constraints and criteria, production systems and methods of connection to the grid, problemrelated to implementation of decentralized management tool and its validation are central. Mywork is part of this context. It focuses in particular on the development of energy models,strategies for energy management in a multi-source and multi-load configuration, andespecially, the implementation methods and the validation tools through various test bencheswhere some components are real.This paper analyzes the energy manager “G-homeTech” including several managementfeatures tested on virtual and hybrid test benches that combine both hardware and softwarecomponents in the simulations. This has put communicating actuators to test their relevance.The validations show that the energy manager allows the deletion of peak demand andsavings on the overall energy bill while respecting the technical and regulatory constraints.Predicted events are not always those that occur. We then simulated such situations.Solar radiation and the total consumption of uncontrollable services are different from thosepredicted. This difference has led to over-subscribed electric power which has enabled themanagement mechanism of reactive energy manager. Load shedding orders are thendynamically sent to certain equipement. These orders directly supply models of electricalequipment.According to the relative importance given to cost and comfort, we have shown that theenergy manager can make substantial savings avoiding consumption during price peaks andavoiding over-subscription by erasure, by modulation of heating system operation and byshefting the timed service operation in the most interesting periods in energy.
178

Rezidence Zlatá Pole v Letovicích / Residence Zlatá Pole in Letovice

Novák, Martin January 2020 (has links)
The aim of the diploma thesis is designing the transport infrastructure for the new building of the 4 apartment buildings in Letovice. The design documentation for building permission contains direction and height solution of the building, static and pedestrian traffic and also design traffic signs and outlook’s ratios. The whole newly emerging site is designed as zone 30.
179

Administrativní objekt / Administrative building

Přibylová, Blanka January 2020 (has links)
The diploma thesis deals with project documentation of an office building with an insurance company branch in Brno - Bystrc. The building is designed as a detached building with five floors and one underground floor. The ground plan of the building is rectangular, set in a slightly sloping terrain. The underground floor is located underground garage and technical facilities. On the first floor there is a café and counters. On the second and third floors there are counter halls and on the fourth floor there are office spaces of a private company. The last fifth floor serves as a flat roof exit. The construction system is two-way wall. The building is insulated with thermal insulation and covered with a flat roof.
180

Pokročilé plánování cesty robotu (RRT) / Advanced Robot Path Planning (RRT)

Knispel, Lukáš January 2012 (has links)
Tato diplomová práce práce se zabývá plánováním cesty všesměrového mobilního robotu pomocí algoritmu RRT (Rapidly-exploring Random Tree – Rychle rostoucí náhodný strom). Teoretická část popisuje základní algoritmy plánování cesty a prezentuje bližší pohled na RRT a jeho potenciál. Praktická část práce řeší návrh a tvorbu v zásadě multiplatformní C++ aplikace v prostředí Windows 7 za použití aplikačního frameworku Qt 4.8.0, která implementuje pokročilé RRT algoritmy s parametrizovatelným řešičem a speciálním dávkovým režimem. Tento mód slouží k testování efektivnosti nastavení řešiče pro dané úlohy a je založen na post-processingu a vizualizaci výstupu měřených úloh pomocí jazyka Python. Vypočtené cesty mohou být vylepšeny pomocí zkracovacích algoritmů a výsledná trajektorie odeslána do pohonů Maxon Compact Drive všesměrové mobilní platformy pomocí CANopen. Aplikace klade důraz na moderní grafické uživatelské rozhraní se spolehlivým a výkonným 2D grafickým engine.

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