Abgeschlossene Dissertation
Refine
Document Type
- Doctoral Thesis (42)
Language
- English (26)
- German (14)
- Multiple languages (2)
Keywords
- Agrarprodukt (1)
- Autonomous vessels (1)
- BIPV (1)
- Backstepping control (1)
- Bahnplanung (1)
- Beobachterentwurf (1)
- Bernstein Basis (1)
- Biomedical signals (1)
- Bodensee (1)
- COMSOL Multiphysics (1)
Institute
- Fakultät Bauingenieurwesen (1)
- Fakultät Elektrotechnik und Informationstechnik (1)
- Fakultät Informatik (3)
- Fakultät Maschinenbau (2)
- Fakultät Wirtschafts-, Kultur- und Rechtswissenschaften (3)
- Institut für Optische Systeme - IOS (3)
- Institut für Strategische Innovation und Technologiemanagement - IST (3)
- Institut für Systemdynamik - ISD (8)
- Institut für angewandte Thermo- und Fluiddynamik - IATF (1)
- Konstanz Institut für Corporate Governance - KICG (1)
Particularly for manufactured products subject to aesthetic evaluation, the industrial manufacturing process must be monitored, and visual defects detected. For this purpose, more and more computer vision-integrated inspection systems are being used. In optical inspection based on cameras or range scanners, only a few examples are typically known before novel examples are inspected. Consequently, no large data set of non-defective and defective examples could be used to train a classifier, and methods that work with limited or weak supervision must be applied. For such scenarios, I propose new data-efficient machine learning approaches based on one-class learning that reduce the need for supervision in industrial computer vision tasks. The developed novelty detection model automatically extracts features from the input images and is trained only on available non-defective reference data. On top of the feature extractor, a one-class classifier based on recent developments in deep learning is placed. I evaluate the novelty detector in an industrial inspection scenario and state-of-the-art benchmarks from the machine learning community. In the second part of this work, the model gets improved by using a small number of novel defective examples, and hence, another source of supervision gets incorporated. The targeted real-world inspection unit is based on a camera array and a flashing light illumination, allowing inline capturing of multichannel images at a high rate. Optionally, the integration of range data, such as laser or Lidar signals, is possible by using the developed targetless data fusion method.
IT-Compliance in KMU
(2023)
Trotz des dringenden Erfordernisses einer nachhaltigen und unabhängigen Energieerzeugung und bereits steigender Anteile photovoltaisch erzeugten Stroms stockt die Verbreitung der bauwerkintegrierten Photovoltaik (BIPV). Zahlreiche „Leuchtturm“-Projekte zeigen das große ästhetische Potential solaraktiver Bauteile und dennoch werden insbesondere von Architekt/innen-Seite neben vermeintlichen Einschränkungen in der planerischen Freiheit immer wieder auch gestalterische Vorbehalte angeführt.
Bisher wurde im Zusammenhang mit PV-Bauteilen schwerpunktmäßig die technische und konstruktive Einfügung thematisiert. Um einen Beitrag zur Diskussion um die Entwicklung visuell überzeugender Ergebnisse zu leisten, die verhindern, dass photovoltaische Bauteile am Gebäude als Fremdkörper wahrgenommen werden, ermittelt die vorliegende Arbeit auf der Grundlage ästhetischer Architekturtheorien allgemeingültige Kriterien für architektonische Wirkungsqualität und transferiert diese auf den Bereich der BIPV-Gestaltung.
Dabei werden zum Verständnis erforderliche Grundlagen der BIPV-Systemtechnik vermittelt sowie verfügbare Bauteile und die unterschiedlichen Akteure und Ziele bei der Gestaltung von BIPV aufzeigt. Auch die speziellen funktionalen und technischen Anforderungen, die PV-Bauteile als „aktive“ Bauteile stellen, werden berücksichtigt und hinsichtlich ihrer hemmenden oder synergetischen Wechselwirkungen differenziert.
Im Rahmen einer Projektstudie finden die oben genannten Kriterien Anwendung auf 13 „best practice“-Beispiele aktueller Wettbewerbsgewinner des vom Solarenergieförderverein Bayern e. V. (SeV) ausgelobten „Architekturpreis Gebäudeintegrierte Solartechnik“, die in Form von Steckbriefen vergleichend dargestellt werden.
Das Ergebnis ist die Synthese eines Kriterienkatalogs als Orientierungs-, Planungs- und Kommunikationswerkzeug, in dem alle Ergebnisse systematisiert zusammengestellt werden.
Ergänzend wird in einem kurzen Exkurs auf von der Hauptuntersuchung ausgenommene, für die Praxis aber relevante Schnittstellen zu wirtschaftlichen Aspekten eingegangen.
Public-key cryptographic algorithms are an essential part of todays cyber security, since those are required for key exchange protocols, digital signatures, and authentication. But large scale quantum computers threaten the security of the most widely used public-key cryptosystems. Hence, the National Institute of Standards and Technology ( NIST ) is currently in a standardization process for post-quantum secure public-key cryptography. One type of such systems is based on the NP-complete problem of decoding random linear codes and therefore called code-based cryptography. The best-known code-based cryptographic system is the McEliece system proposed in 1978 by Robert McEliece. It uses a scrambled generator matrix as a public key and the original generator matrix as well as the scrambling as private key. When encrypting a message it is encoded in the public code and a random but correctable error vector is added. Only the legitimate receiver can correct the errors and decrypt the message using the knowledge of the private key generator matrix. The original proposal of the McEliece system was based on binary Goppa codes, which are also considered for standardization. While those codes seem to be a secure choice, the public keys are extremely large, limiting the practicality of those systems. Many different code families were proposed for the McEliece system, but many of them are considered insecure since attacks exist, which use the known code structure to recover the private key. The security of code-based cryptosystems mainly depends on the number of errors added by the sender, which is limited by the error correction capability of the code. Hence, in order to obtain a high security for relatively short codes one needs a high error correction capability. Therefore maximum distance separable ( MDS ) codes were proposed for those systems, since those are optimal for the Hamming distance. In order to increase the error correction capability we propose q -ary codes over different metrics. There are many code families that have a higher minimum distance in some other metric than in the Hamming metric, leading to increased error correction capability over this metric. To make use of this one needs to restrict not only the number of errors but also their value. In this work, we propose the weight-one error channel, which restricts the error values to weight one and can be applied for different metrics. In addition we propose some concatenated code constructions, which make use of this restriction of error values. For each of these constructions we discuss the usability in code-based cryptography and compare them to other state-of-the-art code-based cryptosystems. The proposed code constructions show that restricting the error values allows for significantly lower public key sizes for code-based cryptographic systems. Furthermore, the use of concatenated code constructions allows for low complexity decoding and therefore an efficient cryptosystem.
This thesis presents the development of two different state-feedback controllers to solve the trajectory tracking problem, where the vessel needs to reach and follow a time-varying reference trajectory. This motion problem was addressed to a real-scaled fully actuated surface vessel, whose dynamic model had unknown hydrodynamic and propulsion parameters that were identified by applying an experimental maneuver-based identification process. This dynamic model was then used to develop the controllers. The first one was the backstepping controller, which was designed with a local exponential stability proof. For the NMPC, the controller was developed to minimize the tracking error, considering the thrusters’ constraints. Moreover, both controllers considered the thruster allocation problem and counteracted environmental disturbance forces such as current, waves and wind.The effectiveness of these approaches was verified in simulation using Matlab/Simulink and GRAMPC (in the case of the NMPC), and in experimental scenarios, where they were applied to the vessel, performing docking maneuvers at the Rhine River in Constance (Germany).
In spite of the amount of new tools and methodologies adopted in the road infrastructure sector, the performance of road infrastructure projects is not constantly improving. Considering that the volume of projects undertaken is forecasted to increase every year, this is a substantial issue for the road infrastructure sector. Hence this work focuses on the principles of Blockchain Technology, road infrastructure sector and the information exchange with the aim to use the advantages of the Blockchain Technology in supporting to overcome the various challenges along the life cycle of road infrastructure projects.
Within the scope of this paper, two studies were conducted. First, focus groups were used to explore where society (road infrastructure sector) stands in terms of industry 4.0 and to get a better understanding if and where the principles of Blockchain Technology can be used when managing projects in the road infrastructure sector. Second, semi-structured interviews were administrated with experts of the road infrastructure sector and experts of Blockchain Technology to better understand the interrelation between these two areas. Based on the outcome of the two studies, technology barriers and enablers were explored for the purpose of improved information exchange within the road infrastructure sector.
The two studies revealed that there are significant and strong interrelations between the principles of the Blockchain Technology, project management within the road infrastructure sector and information exchange. These interrelations are complex and diverse, but overall it can be concluded that the adoption of the principles of Blockchain Technology into the field of information exchange improves the management of road infrastructure projects. Based on the two studies a theoretical framework was developed.
In summary this research showed that trust is an important factor and builds the foundation for communication and to ensure a proper information exchange. Within the scope of this thesis, it was demonstrated that the principles of the Blockchain Technology can be used to increase transparency, traceability and immutability during the life cycle of road infrastructure projects in the area of information exchange.
