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Dissertation
Interferometrisch messender faseroptischer Sensor mit mechanisch oszillierender Sonde
(2015-07-14)
Punktförmig messende optische Sensoren zum Erfassen von Oberflächentopografien im Nanometerbereich werden in der Forschung und Industrie benötigt. Dennoch ist die Auswahl unterschiedlicher Technologien und kommerziell verfügbarer Sensoren gering. In dieser Dissertationsschrift werden die wesentlichen Aspekte eines Messsystems untersucht das über das Potenzial verfügt, zu den künftigen Standardmessmethoden zu gehören. Das Messprinzip beruht auf einem Common-Path-Interferometer. In einer mikrooptischen Sonde wird das ...
Dissertation
Model Calculations for Characterisation and Implementation of Vertical Thin-Layer Structures with Distributed Cavity Mode for Filter and Laser Applications
(2018-04-11)
This work focusses on the approach of optical thin-layer filters with distributed cavity mode. Fabry-Pérot filters own a single cavity layer in the centre of the stack. In contrast, with chirped filter approach the cavity thickness is distributed over several layers. Model calculation results are applied to characterise the properties of the spectrum and the electric field of chirped filters. The aim of distributing the cavity within the filter stack is to distribute the electric field in the resonance case (transmission ...
Dissertation
Large-Size AlGaN/GaN HEMT Large-Signal Electrothermal Characterization and Modeling for Wireless Digital Communications
(2012-03-29)
The rapid growth in high data rate communication systems has introduced new high spectral efficient modulation techniques and standards such as LTE-A (long term evolution-advanced) for 4G (4th generation) systems. These techniques have provided a broader bandwidth but introduced high peak-to-average power ratio (PAR) problem at the high power amplifier (HPA) level of the communication system base transceiver station (BTS). To avoid spectral spreading due to high PAR, stringent requirement on linearity is needed which ...
Dissertation
Optimization-Based Robotic Manipulation for Safe Interaction with Human Operators
(2014-05-02)
This thesis investigates a method for human-robot interaction (HRI) in order to uphold productivity of industrial robots like minimization of the shortest operation time, while ensuring human safety like collision avoidance. For solving such problems an online motion planning approach for robotic manipulators with HRI has been proposed. The approach is based on model predictive control (MPC) with embedded mixed integer programming.
The planning strategies of the robotic manipulators mainly considered in the thesis ...
Dissertation
Highly Sensitive Sensor Based On Intracavity Laser Absorption Spectroscopy By Means of Relative Intensity Noise
(2011-01-07)
This thesis concerns with the main aspects of medical trace molecules detection by means of intracavity laser absorption spectroscopy (ICLAS), namely with the equirements for highly sensitive, highly selective, low price, and compact size sensor. A novel two modes semiconductor laser sensor is demonstrated. Its operation principle is based on the competition between these two modes. The sensor sensitivity is improved when the sample is placed inside the two modes laser cavity, and the competition between the two modes ...
Dissertation
Self-Healing in Autonomous Robot Teams
(2017-05-24)
Today, robots are used in nearly every type of automated manufacturing and assembly process. Robot installations typically apply static actuator systems in clearly structured environments. These systems show impressive abilities in speed and accuracy for repetitive manipulation tasks. Future automation applications, however, require an increasing level of flexibility, where classical systems reach their physical limits. As a reaction, robots become mobile, intelligent and cooperative. These new characteristics, ...
Dissertation
Context as a Service
(2013-03-22)
In the vision of Mark Weiser on ubiquitous computing, computers are disappearing from the focus of the users and are seamlessly interacting with other computers and users in order to provide information and services. This shift of computers away from direct computer interaction requires another way of applications to interact without bothering the user. Context is the information which can be used to characterize the situation of persons, locations, or other objects relevant for the applications.
Context-aware ...
Dissertation
Information Exchange and Fusion in Dynamic and Heterogeneous Distributed Environments
(2010-12-10)
Context awareness, dynamic reconfiguration at runtime and heterogeneity are key characteristics of future distributed systems, particularly in ubiquitous and mobile computing scenarios. The main contributions of this dissertation are theoretical as well as architectural concepts facilitating information exchange and fusion in heterogeneous and dynamic distributed environments. Our main focus is on bridging the heterogeneity issues and, at the same time, considering uncertain, imprecise and unreliable sensor information ...
Dissertation
Decision Making for Teams of Mobile Robots
(2016-11-02)
In the past years, we could observe a significant amount of new robotic systems in science, industry, and everyday life. To reduce the complexity of these systems, the industry constructs robots that are designated for the execution of a specific task such as vacuum cleaning, autonomous driving, observation, or transportation operations. As a result, such robotic systems need to combine their capabilities to accomplish complex tasks that exceed the abilities of individual robots. However, to achieve emergent cooperative ...
Dissertation
Managing Quality Properties of Web Service Compositions
(2015-04-28)
Web services from different partners can be combined to applications that realize a more complex business goal. Such applications built as Web service compositions define how interactions between Web services take place in order to implement the business logic. Web service compositions not only have to provide the desired functionality but also have to comply with certain Quality of Service (QoS) levels. Maximizing the users' satisfaction, also reflected as Quality of Experience (QoE), is a primary goal to be achieved ...