http://dl.gi.de/handle/20.500.12116/36641 2026-07-21T13:24:58Z http://dl.gi.de/handle/20.500.12116/36650 Causal loops: Logically consistent correlations, time travel, and computation Baumeler, Ämin Causal loops are loops in cause-effect relations, where, say for two events A , B , the event A is a cause of B and, vice versa, B is a cause of A . Such loops are traditionally ruled out due to potential logical problems, e. g. , where an effect suppresses its own cause. Motivated by our current physical theories, we show that not only causal loops exist that are logically consistent, but that these loops are computationally tame and help to further investigate on the theoretical foundations of time travel. Causal loops do not necessarily pose problems from a logics, computer-science, and physics point of view. This opens their potential applicability in various fields from philosophy of language to computer science and physics. 2019-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/36647 Tracing local energy markets: A literature review Mengelkamp, Esther; Diesing, Julius; Weinhardt, Christof We conduct a structured literature review on the concept of local energy markets (LEMs). LEMs have gained increasing attention in the last two decades. Yet, a holistic definition and clear demarcation of LEMs is still missing. The review shows current works to shift their focus from conceptual implementation and design to increasingly realistic applications of LEMs. Secure access to (near) real-time smart meter data is a prerequisite for LEMs. Current research gaps, e. g. the inclusion of network constraints, agent-centric LEM designs or a comparison of market mechanisms, are identified. 2019-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/36651 Face2Face: Real-time facial reenactment Thies, Justus This article summarizes the dissertation “Face2Face: Realtime Facial Reenactment” by Justus Thies (Eurographics Graphics Dissertation Online, 2017). It shows advances in the field of 3D reconstruction of human faces using commodity hardware. Besides the reconstruction of the facial geometry and texture, real-time face tracking is demonstrated. The developed algorithms are based on the principle of analysis-by-synthesis. To apply this principle, a mathematical model that represents a face virtually is defined. Utilizing this model to synthesize facial imagery, the model parameters are adjusted, such that the synthesized image fits the input image as good as possible. Thus, in reverse, this process transfers the input image to a virtual representation of the face. The achieved quality allows many new applications that require a good reconstruction of the face. One of these applications is the so-called “Facial Reenactment”. Our developed methods show that such an application does not need any special hardware. The generated results are nearly photo-realistic videos that show the transfer of the expressions of one person to another person. These techniques can for example be used to bring movie dubbing to a new level. Instead of adapting the audio to the video, which might also include changes of the text, the video can be post-processed to match the mouth movements of the dubber. Since the approaches that are shown in the dissertation run in real-time, one can also think of a live dubber in a video teleconferencing system that simultaneously translates the speech of a person to another language. The published videos of the projects in this dissertation led to a broad discussion in the media. On the one hand this is due to the fact that our methods are designed such that they run in real-time and on the other hand that we reduced the hardware requirements to a minimum while improving the resulting quality. In fact, after some preprocessing, we are able to edit ordinary videos from the Internet in real-time. Amongst others, we impose a different mimic to faces of prominent persons like former presidents of the United States of America. This led inevitably to a discussion about trustworthiness of video material, especially from unknown source. Most people did not expect that such manipulations are possible, neglecting existing methods that are already able to edit videos (e. g. special effects in movie productions). Thus, besides the advances in real-time face tracking, our projects raised the awareness of video manipulation. 2019-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/36645 Perspectives on data availability and market approaches to congestion management Richter, Bent; Staudt, Philipp Transmission grid congestion is one of the consequences of an increasing power generation from intermittent renewable capacities. These are often installed in the periphery and have rare generation peaks. It thus becomes more complicated to ensure a balanced grid operation at all times. It is necessary to develop holistic strategies for the management of congestion that consider short and long operating horizons. This paper introduces several congestion management mechanisms along minimal analytical and numerical models. These solutions are then discussed in regard to the necessary data availability and their contribution to an improved congestion management strategy. The paper therefore contributes to the development of a research agenda at the intercept between economists and computer scientists in the area of energy informatics. 2019-01-01T00:00:00Z