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Now showing items 311-320 of 329
Dissertation
A User-Centric Perspective on Parallel Programming with Focus on OpenMP
(2008-01-16)
The process of developing software that takes advantage of multiple processors is commonly referred to as parallel programming. For various reasons, this process is much harder than the sequential case. For decades, parallel programming has been a problem for a small niche only: engineers working on parallelizing mostly numerical applications in High Performance Computing. This has changed with the advent of multi-core processors in mainstream computer architectures. Parallel programming in our days becomes a problem ...
Dissertation
Low-Cost Micromechanically Tunable Optical Devices: Strained Resonator Engineering, Technological Implementation and Characterization
(2006-02-22)
The rapid growth of the optical communication branches and the enormous demand for more bandwidth require novel networks such as dense wavelength division multiplexing (DWDM). These networks enable higher bitrate transmission using the existing optical fibers.
Micromechanically tunable optical microcavity devices like VCSELs, Fabry-Pérot filters and photodetectors are core components of these novel DWDM systems. Several air-gap based tunable devices were successfully implemented in the last years. Even though these ...
Dissertation
Evolving Distributed Algorithms with Genetic Programming
(2009-05-11)
Distributed systems are one of the most vital components of the economy. The most prominent example is probably the internet, a constituent element of our knowledge society. During the recent years, the number of novel network types has steadily increased. Amongst others, sensor networks, distributed systems composed of tiny computational devices with scarce resources, have emerged. The further development and heterogeneous connection of such systems imposes new requirements on the software development process. Mobile ...
Dissertation
Framework for middleware executed on mobile devices
(2007-10-09)
Die ubiquitäre Datenverarbeitung ist ein attraktives Forschungsgebiet des vergangenen und aktuellen Jahrzehnts. Es handelt von unaufdringlicher Unterstützung von Menschen in ihren alltäglichen Aufgaben durch Rechner. Diese Unterstützung wird durch die Allgegenwärtigkeit von Rechnern ermöglicht die sich spontan zu verteilten Kommunikationsnetzwerken zusammen finden, um Informationen auszutauschen und zu verarbeiten. Umgebende Intelligenz ist eine Anwendung der ubiquitären Datenverarbeitung und eine strategische ...
Dissertation
Zweiachsige Hybriderregung von Synchronmaschinen
(2017-04-25)
Neue Anwendungsfelder von geregelten elektrischen Antrieben, wie beispielsweise die Windenergie und die Elektromobilität, führen zu einer stetig steigenden Nachfrage nach wartungsfreien Systemen mit langen Betriebszeiten. Der Preisverfall der Leistungselektronik bei immer höheren Wirkungsgraden ermöglicht durch geeignete Topologien und entsprechende Regelung deutliche Energieeinsparung beim Betrieb elektrischer Antriebe.
In der Elektromobilität stellen im Besonderen gegensinnige Anforderungen, wie hohe Effizienz bei ...
Dissertation
Trajectory Mapping in Physical and Topical Spaces
(2023)
In this dissertation, two different types of trajectories are investigated. In the engfirst part of this work, we investigate methods for the analysis of physical trajectories. We focus on scenarios, in which signal strengths ofWiFi access points are recorded. In detail, they are recorded through smartphone devices by people moving through a building. By means of theWiFi signal strengths, (physical) trajectories of humans are reconstructed, which reflect the locations visited over time. Accurate localization based ...
Dissertation
Orometry, Intrinsic Dimensionality and Learning: Novel Insights into Network Data
(2023-11)
Today, networks are an integral part of our world. Let it be real-life friendship networks or social connections that are based on social media. In this thesis, we contribute to the understanding of networks by studying networks from three different perspectives. First, we adapt notions and concepts from orometry to metric data and networks to gain novel insights from a local perspective. Specifically, we study measures of local outstandingness and propose concepts to derive small hierarchies from larger networks. ...
Dissertation
Regionalisierung von E-Kfz-Ladestellen in Szenarien für den zukünftigen Ausbau in Deutschland
(2023-04)
Ein wesentlicher Baustein zur Senkung der CO2-Emissionen im Verkehrssektor ist die Elektrifizierung des Individualverkehrs, wobei die schnell wachsende Lade-infrastruktur Auswirkungen auf das Stromnetz hat. Netzberechnungen erfordern die räumliche Verortung von zukünftigen Ladestellen. Die vorliegende Arbeit mo-delliert dafür Heimladestellen und öffentlich zugängliche Ladestellen holistisch und punktgenau, und ist für alle Gemeinden in Deutschland anwendbar. Zunächst wird die Anzahl an Elektrofahrzeugen und Ladestellen ...
Dissertation
Context Awareness for Smartphone-Based Cooperative VRU Collision Avoidance
(2024)
Nach Angaben der Weltgesundheitsorganisation sterben weltweit noch immer jährlich rund 1,35 Millionen Menschen bei Verkehrsunfällen. Ungefähr 54% dieser Todesfälle ereignen sich unter ungeschützten Verkehrsteilnehmern wie Fußgängern, Radfahrern und Motorradfahrern. Fußgänger und Radfahrer machen dabei zusammen rund 26% aller Verkehrstoten aus. Im Gegensatz zu fahrzeugbasierten Kollisionsvermeidungssystemen setzen kooperative Systeme die Verwendung von mobilen Geräten wie Smartphones zur kontinuierlichen Erfassung von ...
Aufsatz
Continuous Feature Networks: A Novel Method to Process Irregularly and Inconsistently Sampled Data With Position-Dependent Features
(2023-12-30)
Continuous Kernels have been a recent development in convolutional neural networks. Such kernels are used to process data sampled at different resolutions as well as irregularly and inconsistently sampled data. Convolutional neural networks have the property of translational invariance (e.g., features are detected regardless of their position in the measurement domain), which is unsuitable if the position of detected features is relevant for the prediction task. However, the capabilities of continuous kernels to ...