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Die vorliegende Arbeit erörtert Ansätze für „Zeitmaschinen“, die in Einklang mit der modernen Physik stehen. Besprochen werden u. a. die Tachyonen-Hypothese, Tiplers rotierender Zylinder, der Gödel-Kosmos, der Anti-de-Sitter-Kosmos und die sogenannten „Wurmlöcher“. Zugleich sollen Ansätze vorgestellt werden (z. B. Eternalismus, Viele-Welten-Modell, Prinzip der konsistenten Geschichte), die Lösungsversuche für die Paradoxien von Vergangenheitsreisen bieten. Obwohl erstaunlicherweise die fundamentalen Gesetze der Physik (abgesehen von extrem seltenen und makroskopisch nicht in Erscheinung tretenden quantenmechanischen Effekten) bei einer Zeitumkehr nicht verletzt sind, scheint es in der Natur doch ein grundsätzliches Verbot von Vergangenheitsreisen zu geben. Der Physiker Dieter Zeh, dessen Position im Schlusskapitel der Arbeit näher beleuchtet wird, vertritt die Auffassung, dass die Science-Fiction-Literatur zum Thema „Zeitreisen“ überwiegend auf einfachen begrifflichen Fehlern beruhe. Die in Anlehnung an die Allgemeine Relativitätstheorie konstruierten Vorgänge seien bestenfalls genauso „theoretisch möglich“ wie ein Gas, das sich von selbst in einer Ecke des Gefäßes versammelt. Um die Reisen in die Vergangenheit scheint es zu stehen wie mit einer Anfrage an Radio Jerewan; die Antwort lautet stets: „Im Prinzip ja, aber …“ Doch die Faszination dieser Idee wird weiterhin Stoff für die „Fiction“ liefern.:Vorwort 5 1 Was ist Zeit? 9 2 Der Zeitpfeil 15 3 Zeitreisen und Science-Fiction 19 4 Zeitreisen und die moderne Physik 23 4.1 Reisen in die Zukunft 23 4.2 Reisen in die Vergangenheit 27 4.2.1 Überlichtgeschwindigkeit 28 4.2.2 „Pathologische“ Raum-Zeiten 32 a) Rotierende Zylinder 32 b) Der Gödel-Kosmos 33 c) Der Anti-de-Sitter-Kosmos 34 d) Wurmlöcher 35 e) Kosmische Strings 40 5 Die Paradoxien von Vergangenheitsreisen 41 6 Closed time-like curves (CTC’s): Ein Gespräch mit Dieter Zeh 49 Literatur 53

Die vorliegende Arbeit erörtert Ansätze für „Zeitmaschinen“, die in Einklang mit der modernen Physik stehen. Besprochen werden u. a. die Tachyonen-Hypothese, Tiplers rotierender Zylinder, der Gödel-Kosmos, der Anti-de-Sitter-Kosmos und die sogenannten „Wurmlöcher“. Zugleich sollen Ansätze vorgestellt werden (z. B. Eternalismus, Viele-Welten-Modell, Prinzip der konsistenten Geschichte), die Lösungsversuche für die Paradoxien von Vergangenheitsreisen bieten. Obwohl erstaunlicherweise die fundamentalen Gesetze der Physik (abgesehen von extrem seltenen und makroskopisch nicht in Erscheinung tretenden quantenmechanischen Effekten) bei einer Zeitumkehr nicht verletzt sind, scheint es in der Natur doch ein grundsätzliches Verbot von Vergangenheitsreisen zu geben. Der Physiker Dieter Zeh, dessen Position im Schlusskapitel der Arbeit näher beleuchtet wird, vertritt die Auffassung, dass die Science-Fiction-Literatur zum Thema „Zeitreisen“ überwiegend auf einfachen begrifflichen Fehlern beruhe. Die in Anlehnung an die Allgemeine Relativitätstheorie konstruierten Vorgänge seien bestenfalls genauso „theoretisch möglich“ wie ein Gas, das sich von selbst in einer Ecke des Gefäßes versammelt. Um die Reisen in die Vergangenheit scheint es zu stehen wie mit einer Anfrage an Radio Jerewan; die Antwort lautet stets: „Im Prinzip ja, aber …“ Doch die Faszination dieser Idee wird weiterhin Stoff für die „Fiction“ liefern.:Vorwort 5 1 Was ist Zeit? 9 2 Der Zeitpfeil 15 3 Zeitreisen und Science-Fiction 19 4 Zeitreisen und die moderne Physik 23 4.1 Reisen in die Zukunft 23 4.2 Reisen in die Vergangenheit 27 4.2.1 Überlichtgeschwindigkeit 28 4.2.2 „Pathologische“ Raum-Zeiten 32 a) Rotierende Zylinder 32 b) Der Gödel-Kosmos 33 c) Der Anti-de-Sitter-Kosmos 34 d) Wurmlöcher 35 e) Kosmische Strings 40 5 Die Paradoxien von Vergangenheitsreisen 41 6 Closed time-like curves (CTC’s): Ein Gespräch mit Dieter Zeh 49 Literatur 53

Modern general purpose programming languages like Java or C# provide a rich feature set and a higher degree of abstraction than conventional real-time programming languages like C/C++ or Ada. Applications developed with these modern languages are typically deployed via platform independent intermediate code. The intermediate code is typically executed by a virtualizing runtime environment. This allows for a high portability. Prominent examples are the Dalvik Virtual Machine of the Android operating system, the Java Virtual Machine as well as Microsoft .NET’s Common Language Runtime. The virtualizing runtime environment executes the instructions of the intermediate code. This introduces additional challenges to real-time software development. One issue is the transformation of the intermediate code instructions to native code instructions. If this transformation interferes with the execution of the real-time application, this might introduce jitter to its execution times. This can degrade the quality of soft real-time systems like augmented reality applications on mobile devices, but can lead to severe problems in hard real-time applications that have strict timing requirements. This thesis examines the possibility to overcome timing issues with intermediate code execution in virtualizing runtime environments. It addresses real-time suitable generation of native code from intermediate code in particular. In order to preserve the advantages of modern programming languages over conventional ones, the solution has to adhere to the following main requirements: - Intermediate code transformation does not interfere with application execution - Portability is not reduced and code transformation is still transparent to a programmer - Comparable performance Existing approaches are evaluated. A concept for real-time suitable code generation is developed. The concept bases on a pre-allocation of the native code and the elimination of indirect references, while considering and optimizing startup time of an application. This concept is implemented by the extension of an existing virtualizing runtime environment, which does not target real-time systems per se. It is evaluated qualitatively and quantitatively. A comparison of the new concept to existing approaches reveals high execution time determinism and good performance and while preserving the portability deployment of applications via intermediate code.

Several cloud providers offer reltional databases as part of their portfolio. It is however not obvious how resource virtualization and sharing, which is inherent to cloud computing, influence performance and predictability of these cloud databases. Cloud providers give little to no guarantees for consistent execution or isolation from other users. To evaluate the performance isolation capabilities of two commercial cloud databases, we ran a series of experiments over the course of a week (a query, a minute) and report variations in query response times. As a baseline, we ran the same experiments on a dedicated server in our data center. The results show that in the cloud single outliers are up to 31 times slower than the average. Additionally, one can see a point in time after which the average performance of all executed queries improves by 38 %.

As cycling becomes more popular and automated driving is on the rise, it can be assumed that in the city of the future highly automated vehicles (HA Vs) and cyclists will share the same roads. Yet only little is known about how cyclists announce their maneuvers to motorized vehicles or how they communicate and interact with them. Knowledge on these aspects is currently missing to guide the design of cyclist-HA V interactions. Situations where a cyclist rides upfront a vehicle, will be especially challenging for HA Vs, such as when a cyclist (A) avoids an obstacle on the road section ahead, (B) merges onto the road from an ending cycling path, or (C) leaves the road turning into a driveway {see Figure 1) [1 ]. Based on the cyclist's intention, the HA V will have to pass or keep following with only limited options to communicate to the cyclist ahead. Design solutions derived from the well-studied field of pedestrian-HA V interactions cannot simply be transferred to the here considered cyclist-HA V interactions, since in past research successful design concepts for pedestrians were not beneficial for cyclists [2]. Hence, it is vital to investigate the behavior and experiences of cyclists in more detail and to explore possible design solutions for HA V interaction behavior in these situations. With this study we aim to get more insights into the subjective experience of cyclists travelling in longitudinal traffic, especially during cyclist-vehicle interactions, as well as to derive cyclists' requirements to design safe and desirable cyclist-HA V interactions.

Multi-tenancy in relational databases has been a topic of interest for a couple of years. On the one hand, ever increasing capabilities and capacities of modern hardware easily allow for multiple database applications to share one system. On the other hand, cloud computing leads to outsourcing of many applications to service architectures, which in turn leads to offerings for relational databases in the cloud, as well. The ability to benchmark multi-tenancy database systems (MT-DBMSs) is imperative to evaluate and compare systems and helps to reveal otherwise unnoticed shortcomings. With several tenants sharing a MT-DBMS, a benchmark is considerably different compared to classic database benchmarks and calls for new benchmarking methods and performance metrics. Unfortunately, there is no single, well-accepted multi-tenancy benchmark for MT-DBMSs available and few efforts have been made regarding the methodology and general tooling of the process. We propose a method to benchmark MT-DBMSs and provide a framework for building such benchmarks. To support the cumbersome process of defining and generating tenants, loading and querying their data, and analyzing the results we propose and provide MULTE, an open-source framework that helps with all these steps.

In this thesis, a context-aware, personalized virtual assistant for use in automobiles is presented. With the increasing use of technology in automobiles, there is a growing need for safer and more practical ways for drivers to access information and perform tasks while driving. Voice-based interfaces, such as natural language processing, provide a solution to this problem as they do not require visual or manual input. In this thesis, a fine-tuned model of GPT-3 is used to understand user intentions and identify the user’s needs. The voice assistant is trained to understand the environment and the actions it can perform. The use of triggers such as drowsiness detection is also implemented to make the virtual assistant proactive in ensuring the user’s safety. User testing and evaluation was conducted to demonstrate the effectiveness of the context-aware, personalized virtual assistant in improving the driving experience and promoting safe driving practices.

Die langfristigen Folgen von psychischer Fehlbeanspruchung stellen ein beträchtliches Problem unserer modernen Gesellschaft dar. Zur Identifizierung derartiger Fehlbelastungen während der Mensch-Maschine-Interaktion (MMI) kann die objektive, kontinuierliche Messung der psychischen Beanspruchung einen wesentlichen Beitrag leisten. Neueste Entwicklungen in der Sensortechnologie und der algorithmischen Methodenentwicklung auf Basis von KI liefern die Grundlagen zu ihrer messtechnischen Bestimmung. Vorarbeiten zur Entwicklung einer Methode zur neuronalen Beanspruchungsdiagnostik sind bereits erfolgt (Radüntz, 2017). Eine praxisrelevante Nutzung dieser Ergebnisse ist erfolgsversprechend, wenn die Methode mit Wearables kombiniert werden kann. Gleichzeitig sind die Evaluation und bedingungsbezogene Reliabilitätsprüfung der entwickelten Methode zur neuronalen Beanspruchungsdiagnostik in realitätsnahen Umgebungen erforderlich. Im Rahmen von experimentellen Untersuchungen der Gebrauchstauglichkeit von kommerziellen EEG-Registrierungssystemen für den mobilen Feldeinsatz wird die darauf basierende Systemauswahl für die MMI-Praxis getroffen. Die Untersuchungen zur Validierung der kontinuierlichen Methode zur Beanspruchungsdetektion erfolgt am Beispiel des Fluglotsenarbeitsplatzes beim simulierten „Arrival Management“. / The long-term negative consequences of inappropriate mental workload on employee health constitute a serious problem for a digitalized society. Continuous, objective assessment of mental workload can provide an essential contribution to the identification of such improper load. Recent improvements in sensor technology and algorithmic methods for biosignal processing are the basis for the quantitative determination of mental workload. Neuronal workload measurement has the advantage that workload registration is located directly there where human information processing takes place, namely the brain. Preliminary studies for the development of a method for neuronal workload registration by use of the electroencephalogram (EEG) have already been carried out [Rad16, Rad17]. For the field use of these findings, the mental workload assess- ment on the basis of the EEG must be evaluated and its reliability examined with respect to several conditions in realistic environments. A further essential require-ment is that the method can be combined with the innovative technologies of gel free EEG registration and wireless signal transmission. Hence, the presented papers include two investigations. Main subject of the first investigation are experimental studies on the usability of commercially-oriented EEG systems for mobile field use and system selection for the future work. Main subject of the second investigation is the evaluation of the continuous method for neuronal mental workload registration in the field. Thereby, a challenging application was used, namely the arrival management of aircraft. The simulation of the air traffic control environment allows the realisation of realistic conditions with different levels of task load. Furthermore, the work is well contextualized in a domain which is very sensible to human-factors research.

This technical report publishes the proceedings of the 26th Bilateral Student Workshop CTU Prague and HTW Dresden - User Interfaces & Visualization -, which was held on the 1st and 2nd December 2023. The workshop offers a possibility for young scientists to present their current research work in the fields of computer graphics, human-computer-interaction, robotics and usability. The workshop is intended to be a platform to bring together researchers from both the Czech Technical University in Prague (CTU) and the University of Applied Sciences Dresden (HTW). The German Academic Exchange Service offers its financial support to allow student participants the bilateral exchange between Prague and Dresden.:1) Václav Pavlovec: Multi-Boundary Labeling, pp. 2–5 2) Philipp Ballin: Influence of Speed, Direction, and Intensity of Vibrotactile Animations onto Emotional Level, pp. 6–14 3) Niklas Maximilian Kothe, Leon Kolosov: Errors In Pictures, pp. 15–21 4) Jan Trávníček: Automatic Sports Equipment Rental Service, pp. 22–26 5) Jimmy Orawetz, Felix Mühlberg: Capturing and Reproducing Atmospheres, pp. 27–32 6) Vojtěch Leischner: Time Based Audio-movement Graph, pp. 33–37 7) Markéta Machová: Balancing Exercises for Seniors in VR with Interactive Elements, pp. 38–41 8) Radka Olyšarová: MediaPipe Based Leg Tracking Method for Sensorimotor Walking Exercise for Elderly in VR, pp. 42–46 9) Vojtěch Radakulan: Application of Diegetic and Non-Diegetic Navigation in Virtual Reality, pp. 47–51 / Dieser Tagungsband enthält die Beiträge des 26. Bilateralen Studentenworkshops der CTU Prag und der HTW Dresden zu User Interfaces & Visualization, der am 1. und 2. Dezember 2023 stattfand. Der Workshop bietet jungen Wissenschaftlerinnen und Wissenschaftlern die Möglichkeit, ihre aktuellen Forschungsarbeiten in den Bereichen Computergrafik, Mensch-Computer-Interaktion, Robotik und Usability zu präsentieren. Der Workshop soll eine Plattform sein, um Forschende der Tschechischen Technischen Universität Prag (CTU) und der Hochschule für Technik und Wirtschaft Dresden (HTW) zusammenzubringen. Der Deutsche Akademische Austauschdienst stellt die finanzielle Unterstützung bereit, um den studentischen Teilnehmenden den bilateralen Austausch zwischen Prag und Dresden zu ermöglichen.:1) Václav Pavlovec: Multi-Boundary Labeling, pp. 2–5 2) Philipp Ballin: Influence of Speed, Direction, and Intensity of Vibrotactile Animations onto Emotional Level, pp. 6–14 3) Niklas Maximilian Kothe, Leon Kolosov: Errors In Pictures, pp. 15–21 4) Jan Trávníček: Automatic Sports Equipment Rental Service, pp. 22–26 5) Jimmy Orawetz, Felix Mühlberg: Capturing and Reproducing Atmospheres, pp. 27–32 6) Vojtěch Leischner: Time Based Audio-movement Graph, pp. 33–37 7) Markéta Machová: Balancing Exercises for Seniors in VR with Interactive Elements, pp. 38–41 8) Radka Olyšarová: MediaPipe Based Leg Tracking Method for Sensorimotor Walking Exercise for Elderly in VR, pp. 42–46 9) Vojtěch Radakulan: Application of Diegetic and Non-Diegetic Navigation in Virtual Reality, pp. 47–51