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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.
11

Katheterablation von Vorhofflimmern

Piorkowski, Christopher 04 October 2010 (has links)
Bedingt durch die zunehmende Prävalenz der Rhythmusstörung Vorhofflimmern mit den assoziierten Morbiditäts- und Mortalitätsrisiken ist die Entwicklung und Etablierung kurativer Therapieverfahren von klinischem und wissenschaftlichem Interesse. Entsprechend dem pathophysiologischen Verständnis der Arrhythmie-induzierenden Triggeraktivität und des Arrhythmie-erhaltenden Flimmersubstrat mit der vorrangigen anatomisch-strukturellen Lokalisation beider Entitäten im Übergangsbereich der großen Pulmonalvenentrichter in den posterioren linken Vorhof wurden katheterinterventionelle Ablationskonzepte als potentiell kurative Therapien entwickelt. Limitationen der praktischen Umsetzung theoretischer Linienkonzepte ergeben sich aus komplexen anatomischen Gegebenheiten und instabilen Zugangsbedingungen infolge Atmung und kardialer Mobilität. Aufbauend auf non-fluoroskopischen Navigationssystemen wurden Verfahren für vollständig Modell-integrierte Ansätze der Ablationslinienplatzierung entwickelt, bei denen Planung, Durchführung und Validierung der Ablation an anatomisch korrekten dreidimensionalen CT-Modellen des linken Vorhofes erfolgen. Zur Verbesserung instabiler Zugangsbedingungen wurden Verfahren der Katheternavigation mittels steuerbaren Schleusensystemen eingeführt und in entsprechenden Studien mit klinischen Endpunkten validiert. Zu objektivierbaren Erfassung von Energietransfer und myokardialer Läsionsbildung während der Ablation wurden katheterinterventionelle Kontakttechnologien, die auf der Messung lokaler komplexer Impedanzen zwischen Katheter und Gewebe beruhen, in der ersten klinischen Anwendung erprobt und validiert. Mit diesen technologischen Entwicklungen gelangen eine zunehmend akkuratere klinische Umsetzung theoretischer Ablationskonzepte und damit eine Etablierung des Therapiekonzeptes als klinisches Standardverfahren. Eine zur Abschätzung des Nutzen/Risiko-Profils nötige detaillierte Komplikationsanalyse stellte die Ösophagusverletzung als schwerste Komplikation heraus, die mit 0,3% selten auftrat, aber für nahezu alle langfristigen Folgeschäden verantwortlich war. Entwicklungen zur periprozeduralen Visualisierung des Ösophagus mit paralleler intraösophagealer Temperaturmessung sind Ansätze zur Vermeidung dieser Komplikation in der Zukunft. Bedingt durch das Auftreten und die postinterventionelle Zunahme asymptomatischer Flimmerrezidive ist die Frage eines objektiven Vorhofflimmermonitorings von entscheidender Bedeutung für die Beurteilung der Effektivität der Ablation sowie weitergehende klinische und wissenschaftliche Fragestellungen; wie die Indikation zur Antikoagulation oder den Vergleich von Rhythmus- und Frequenzkontrolle. 7-Tage-LzEKGs und transtelephonische EKGs wurden als Standard zum Monitoring innerhalb klinischer Vorhofflimmerstudien etabliert. Entwicklungen im Bereich implantierbarer kontinuierlicher Rhythmusmonitore werden in Zukunft das Netz zur Erfassung asymptomatischen Vorhofflimmerns weiter verdichten.
12

Simultaneous Localization And Mapping For A Mobile Robot Operating In Outdoor Environments

Sezginalp, Emre 01 December 2007 (has links) (PDF)
In this thesis, a method to the solution of autonomous navigation problem of a robot working in an outdoor application is sought. The robot will operate in unknown terrain where there is no a priori map present, and the robot must localize itself while simultaneously mapping the environment. This is known as Simultaneous Localization and Mapping (SLAM) problem in the literature. The SLAM problem is attempted to be solved by using the correlation between range data acquired at different poses of the robot. A robot operating outdoors will traverse unstructured terrain, therefore for localization, pitch, yaw and roll angles must also be taken into account along with the (x,y,z) coordinates of the robot. The Iterative Closest Points (ICP) algorithm is used to find this transformation between different poses of the robot and find its location. In order to collect the range data, a system composing of a laser range finder and an angular positioning system is used. During localization and mapping, odometry data is fused with range data.
13

Um framework para avaliação de mapeamento tridimensional Utilizando técnicas de estereoscopia e odometria visual / Three-dimensional mapping of external environments through Stereoscopy and visual odometry techniques

Santos, Cristiano Flores dos 30 March 2016 (has links)
The three-dimensional mapping environments has been intensively studied in the last decade. Among the benefits of this research topic is possible to highlight the addition of autonomy for car or even drones. The three-dimensional representation also allows viewing of a given scenario iteratively and with greater detail. However, until the time of this work was not found one framework to present in detail the implementation of algorithms to perform 3D mapping outdoor approaching a real-time processing. In view of this, in this work we developed a framework with the main stages of three-dimensional reconstruction. Therefore, stereoscopy was chosen as a technique for acquiring the depth information of the scene. In addition, this study evaluated four algorithms depth map generation, where it was possible to achieve the rate of 9 frames per second. / O mapeamento tridimensional de ambientes tem sido intensivamente estudado na última década. Entre os benefícios deste tema de pesquisa é possível destacar adição de autonomia á automóveis ou mesmo drones. A representação tridimensional também permite a visualização de um dado cenário de modo iterativo e com maior riqueza de detalhes. No entanto, até o momento da elaboração deste trabalho não foi encontrado um framework que apresente em detalhes a implementação de algoritmos para realização do mapeamento 3D de ambientes externos que se aproximasse de um processamento em tempo real. Diante disto, neste trabalho foi desenvolvido um framework com as principais etapas de reconstrução tridimensional. Para tanto, a estereoscopia foi escolhida como técnica para a aquisição da informação de profundidade do cenário. Além disto, neste trabalho foram avaliados 4 algoritmos de geração do mapa de profundidade, onde foi possível atingir a taxa de 9 quadros por segundo.
14

Truncated Signed Distance Fields Applied To Robotics

Canelhas, Daniel Ricão January 2017 (has links)
This thesis is concerned with topics related to dense mapping of large scale three-dimensional spaces. In particular, the motivating scenario of this work is one in which a mobile robot with limited computational resources explores an unknown environment using a depth-camera. To this end, low-level topics such as sensor noise, map representation, interpolation, bit-rates, compression are investigated, and their impacts on more complex tasks, such as feature detection and description, camera-tracking, and mapping are evaluated thoroughly. A central idea of this thesis is the use of truncated signed distance fields (TSDF) as a map representation and a comprehensive yet accessible treatise on this subject is the first major contribution of this dissertation. The TSDF is a voxel-based representation of 3D space that enables dense mapping with high surface quality and robustness to sensor noise, making it a good candidate for use in grasping, manipulation and collision avoidance scenarios. The second main contribution of this thesis deals with the way in which information can be efficiently encoded in TSDF maps. The redundant way in which voxels represent continuous surfaces and empty space is one of the main impediments to applying TSDF representations to large-scale mapping. This thesis proposes two algorithms for enabling large-scale 3D tracking and mapping: a fast on-the-fly compression method based on unsupervised learning, and a parallel algorithm for lifting a sparse scene-graph representation from the dense 3D map. The third major contribution of this work consists of thorough evaluations of the impacts of low-level choices on higher-level tasks. Examples of these are the relationships between gradient estimation methods and feature detector repeatability, voxel bit-rate, interpolation strategy and compression ratio on camera tracking performance. Each evaluation thus leads to a better understanding of the trade-offs involved, which translate to direct recommendations for future applications, depending on their particular resource constraints.
15

[en] EVALUATION OF A 3D RECONSTRUCTION ALGHORITHM WITH RGB-D SENSORS / [pt] AVALIAÇÃO DE UM ALGORITMO DE RECONSTRUÇÃO 3D COM SENSORES RGB-D

IAN MEDEIROS COELHO 16 January 2017 (has links)
[pt] Sensores de profundidade do tipo RGB-D são alternativas interessantes para realizar a reconstrução 3D do ambiente a um baixo custo. Neste trabalho, avaliamos uma pipe-line de reconstrução implementada em GPU que une um sistema de tracking baseado no alinhamento de nuvem de pontos para estimar a posição da câmera e um sistema de reconstrução/visualização volumétrica para suavizar as medidas naturalmente ruidosas do sensor, utilizando o Kinect como entrada RGB-D. Foi feita uma análise técnica do algoritmo, demonstrando o impacto de modificações de parâmetros do sistema, além de um comparativo de tempo e precisão entre a implementação aqui apresentada e uma versão pública disponibilizada pela Point Cloud Library(PCL) durante o desenvolvimento deste trabalho. Algumas modificações em relação ao trabalho original foram feitas e os testes de desempenho demonstram que nossa implementação é mais rápida do que a da PCL sem comprometer significantemente a precisão da reconstrução. / [en] Depth sensors of the type RGB-D are interesting alternatives to do a 3D reconstruction of the environment with low cost. In this work, we evaluate a reconstruction pipe-line implemented on GPU that merges a point cloud alignment tracking system to estimate the camera position and a volumetric reconstruction/visualization to smooth the naturally noise measures from the sensor, using the Kinect as RGB-D input. A technical analysis of the algorithm has been made, showing the impact of parameter modifications of the system and a comparative of time and precision between the presented implementation and a public version available by the Point Cloud Library (PCL) during the development of this work. Some modifications to the original work have been made and the performance tests demonstrate that our implementation is faster than the PCL version without compromising the reconstruction precision.
16

3D mapování vnitřního prostředí senzorem Microsoft Kinect / 3D indoor mapping using Microsoft Kinect

Pilch, Petr January 2013 (has links)
This work is focused on creating 3D maps of indoor enviroment using Microsoft Kinect sensor. The first part shows the description of Microsoft Kinect sensor, the methods for acquisition and processing of depth data and their registration using different algorithms. The second part shows application of algorithms for map registration and final 3D maps of indoor enviroment.
17

3D Mapping of Islamic Geometric Motifs

Sayed, Zahra January 2017 (has links)
In this thesis a novel approach in generating 3D IGP is applied using shape grammar, an effective pattern generation method. The particular emphasis here is to generate the motifs (repeat unit) in 3D using parameterization, which can then be manipulated within 3D space to construct architectural structures. Three unique distinctive shape grammar algorithms were developed in 3D; Parameterized Shape Grammar (PSG), Auto-Parameterized Shape Grammar (APSG) and Volumetric Shell Shape Grammar (VSSG). Firstly, the PSG generates the motifs in 3D. It allows one to use a single changeable regular 3D polygon, and forms a motif by given grammar rules including, Euclidean transformations and Boolean operations. Next, APSG was used to construct the architectural structures that manipulates the motif by automating the grammar rules. The APSG forms a wall, a column, a self-similarity star and a dome, the main features of Islamic architecture. However, applying Euclidean transformations to create non-Euclidean surfaces resulted in gaps and or overlaps which does not form a perfect tessellation. This is improved upon by the VSSM, which integrates two key methods, shell mapping and coherent point drift, to map an aesthetically accurate 3D IGM on a given surface. This work has successfully presented methods for creating complex intricate 3D Islamic Geometric Motifs (IGM), and provided an efficient mapping technique to form visually appealing decorated structures. / Partially funded by the Centre of Visual Computing (CVC)
18

Combining dense short range sensors and sparse long range sensors for mapping

Lin, Ismael January 2018 (has links)
Mapping is one of the main components of autonomous robots, and consist in the construction of a model of their environment based on the information gathered by different sensors over time. Those maps will have different attributes depending on the type of sensor used for the reconstruction. In this thesis we focus on RGBD cameras and LiDARs. The acquired data with cameras is dense, but the range is short and the construction of large scale and consistent maps is more challenging. LiDARs are the exact opposite, they give sparse data but can measure long ranges accurately and therefore support large scale mapping better. The thesis presents a method that uses both types of sensors with the purpose of combine their strengths and reduce their weaknesses. The evaluation of the system is done in an indoor environment, and with an autonomous robot. The result of the thesis shows a map that is robust in large environments and has dense information of the surroundings. / Kartläggning är en av huvudkomponenterna för autonoma robotar, och består av att bygga en modell av miljön utifrån informationen som samlats in av olika sensorer över tid. Dessa kartor kommer att ha olika attribut beroende på vilken typ av sensor som används för rekonstruktionen. I denna avhandling är fokus på RGBD-kameror och LiDARs. Datan från kameror är kompakt men kan bara mäta korta sträckor och det är utmanande att konstruera storskaliga och konsistenta kartor. LiDARs är exakt motsatta, de ger gles data men kan mäta långa avstånd noggrant och stödjer därför storskalig kartering bättre. Avhandlingen presenterar en metod som använder båda typerna av sensorer i syfte att kombinera deras styrkor och minska svagheterna. Utvärderingen av systemet sker i en inomhusmiljö och med en autonom robot. Resultatet av avhandlingen visar en karta som är robust i stora miljöer och har tät information om omgivningen.
19

Anwendung von photogrammetrischen Scans im Projection Mapping

Gotthardt, Robert 22 December 2023 (has links)
Diese Arbeit untersucht die Funktionsweise, Herausforderungen und Lösungsansätze des 2D- und 3D Projection Mappings. Insbesondere wird darauf eingegangen, wie dreidimensionale Abbildungen der Realität (3D Scans) genutzt werden und wie sie erstellt werden können, wobei der Fokus auf 3D Scans liegt, die durch photogrammetrische Rekonstruktion mit der Software Meshroom entstanden sind. Ein Ziel dieser Arbeit besteht darin, die beschriebenen Themen so darzustellen, dass sie auch für semiprofessionelle Endanwender verständlich sind. Die Arbeit soll als umfassende und gebündelte Informationssammlung dienen, die als Grundlage für eigene Projekte und vertiefte Forschungen genutzt werden kann.:I. Einleitung II. Begriffe und Definitionen III. Augmented Reality 1. Direct Augmentation 1.1. Projektionsinhalte 1.2. Einrichtung der Projektoren 1.3. Previsualisierung IV. 3D Rekonstruktionen 2. Analog-Digital-Wandlung 3. Rekonstruktionsmethoden 3.1. Aktive Rekonstruktionen 3.2. Passive Rekonstruktionen 3.3. Stereo- und Multiple-Kamera-Setups 3.4. Tiefenberechnung 3.5. Photogrammetrische Pipeline V. Praxisteil 4. Methodik 5. Vorgehensweise Experimentreihe 1 5.1. Referenzmodelle 5.2. Wahl der Referenzobjekte 5.3. Scanning der Referenzobjekte 5.4. Photogrammetrische Rekonstruktion 5.4.1. Aufzeichnung der Fotodatenbanken 5.4.2. Aufbereitung der Aufnahmen 5.4.3. Meshroom-Pipeline 5.4.4. Aufbereitung der Meshes 5.5. Vergleich der Meshes 6. Ergebnisse 7. Auswertung 8. Vorgehensweise Experimentreihe 2 8.1. Aufbau des Experiments 8.2. Aufzeichung der initialen Rekonstruktionsdatenbank 8.3. Rekonstruktion des Gebäudes 8.4. Aufbereitung des Meshes 8.5. Anfertigung von Vorlagen für die Projektionseinrichtung 8.6. Kreation von Projektionsinhalten 8.7. Virtuelle Visualisierung 9. Ergebnisse 10.Auswertung 11.Diskussion 12.Fazit und Ausblick A. Literaturverzeichnis B. Abbildungsverzeichnis C. Messergebnisse D. Datenbanken E. Abbildungen
20

A Conceptual Design to Enable Lunar 3D Mapping : Analysis Based Design of A Mechanism to Facilitate Electrical Sensor Packaging and Deployment on The Lunar Regolith

Shahrokhi, Fatemehsadat, Keipour, Soheil January 2023 (has links)
The prospect of mining the moon to extract valuable resources that facilitates upcoming space exploration is what the space industry invests in, in recent years.The Lunar exploration is a solid stepping stone to enable further space exploratory missions, especially Mars. However, Moon mining is extremely complex and requires infrastructure before it begins. The CSMC is a Lunar regolith mining company which aims to process oxygen and hydrogen for both fuel and life support in-situ. Since it costs a fortune to transport the resources to the Moon’s sites, these operations will support the development of the infrastructure and technology necessary to create a robust ex-terran economy, benefiting humanity for generations to come. To fulfill this goal, the existing resources in the regolith should be detected by 3D mapping the subterrain of the Moon using sensors. These sensors need to be deposited on the Moon by a rover and would relay the signals back to the rover (and eventually the earth) for processing. This project develops a conceptual design for the configuration and deployment of the sensor probes and analysis. This concept would then form the basis for weight, and stowed envelope estimates as well as ConOps requirements. Then the design undergoes structural analysis to validate the concept’s reliability. The main focus of this thesis is on the structural analysis of the design and evaluating it based on the stress and vibration requirements in excessive environmental conditions. To do so, we used the general steps of NASA’s structural analysis procedure in the conceptual design phase which includes stress analysis, modal analysis, optimization, and redesign. Optimizing the weight of the structure has significant importance in the space sector. So, considering the trade-off between the weight and strength of the structure we redesigned the initial design to achieve lower weight. The digital prototyping and analysis is conducted in Autodesk Inventor and the main parts of the systems are prototyped using the 3D printing method to validate the operation feasibility of the mechanism.

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