Generator Power Optimisation for a More-Electric Aircraft by Use of a Virtual Iron Bird

A prodedure is developed to minimise the generator design power within the electric power system of a future more-/ all-electric aircraft. This allows to save weight on the generators and on other equipment of the electic power system. Execution of the optimisation procedure by hand demonstrates the complexity of the problem. An automation of the process shows the capabilities of integrated modelling, simulation and optimisation tools

Silver nanoparticles - From the synthesis to the biological application

The main topic of this doctoral thesis was the synthesis and characterization of defined silver nanoparticles (Ag NPs). These particles were synthesized with different sizes and modified surface chemistry. Two core sizes were synthesized. One, very small particle (~2 nm core) with hydrophilic ligands at the surface and second, bigger particles (~4.2 nm core) with different kinds of coatings were prepared. Additionally, the potential of these particles were tested for their use in biological systems. For this, they had to be stable in aqueous media. To assess this, their stability against different salt concentration was measured. Another important point, especially for silver nanoparticles, was its cytotoxicity. The cytotoxicity of the silver particles is a very important research topic due to the antimicrobial effect observed in silver NPs. Here, the toxicity of the different particles was measured in two different cell lines. The very small particles (~2 nm), so called nanoclusters (NCs), were prepared in two steps. After the reduction of the silver precursor first an etching step and afterwards a ligand exchange reaction were done. This ligand exchange also allowed the particles to be stable in aqueous media. During the whole synthesis the size and the distribution of the particles changed. At the beginning the particles showed a broad distribution and sizes up to almost 30 nm. After the etching the distribution decreased a lot and the sizes shrunk to 5 nm. The final core size of about 2 nm with a narrow distribution was reached after the ligand exchange being the particles stable in an aqueous suspension. A big advantage of these nanoclusters was that they showed fluorescence in the red and did not need to be labeled with an additional dye for in vitro experiments. The second type of particles showed a core size of around 4.2 nm and was synthesized in a simple reduction reaction. For this reaction first a precursor of the stabilizing ligand had to be synthesized. After the synthesis the particles were stable as a gray powder and showed a hydrophobic surface. To get the particles into aqueous phase two different methods were used. First a ligand exchange reaction with a hydrophilic ligand and second the coating of the particles with an amphiphilic polymer. One advantage of the coating process was the easy modification of the surface afterwards. This was shown by the modification of the particles with a dye and/or polyethylene glycol (PEG) chains. A further advantage was that the toxicity of the particles was highly reduced by this process. This reduced toxicity was on one hand due to the increased stability of the particles and on the other hand due to the reduced uptake of the particles when their surface was saturated with PEG. An increase of the stability against sodium chloride could also been shown for commercial gold particles using the same coating process. The commercial gold nanoparticles were stabilized by citrate molecules at the beginning and so first a ligand exchange including a phase transfer to the organic phase had to be done to reach the same surface like the silver nanoparticles. Nevertheless, the Ag NPs showed a cytotoxic effect, which was due to the release of Ag(I) ions. This release was measured under different pH conditions. Under neutral pH values neither the Ag NPs stabilized by hydrophilic ligand molecules nor the once stabilized by the polymer coating showed a release of more than 0.1% of ions up to 14 days. Under acidic conditions (pH 3) all the particles showed a release of about 1% of ions already after 7 days. In comparison of the total amount of silver with a silver salt the concentration of silver ions from the particles are low but they are “more toxic” because of the better uptake respectively their release inside the cell. To summarize it can be said that a defined synthesis and modification of different Ag NPs could be done but although they showed a very high stability they never lost their cytotoxicity

The Abolition of the Parental Right to Corporal Punishment in Sweden, Germany and other European Countries: A Model for the United States and other Democracies?

Zweitveröffentlichung. Download von https://kfn.de/publikationen/kfn-forschungsbericht

Cheating With Honor

The intent of this paper is to understand what leads a student to cheat within the context of a small (enrollment below 2,000 students) liberal arts college. The development of a model will examine cheating from three categories highlighted in the literature: demographics, college culture, and the perception of cheating. Demographics capture relevant personal attributes of a student such as gender, GPA, and major. Cultural variables include variables for the presence of an honor code and participation in a sport or social organization, which provide that student with a unique cultural experience. Perception variables deal with the perceptions the students have developed about cheating based on the academic culture within which they operate, such as student perception of cheating on campus, perception of peer behavior, and perceived faculty involvement

Multisensory spatial mechanisms of the bodily self and social cognition : a commentary on Vittorio Gallese & Valentina Cuccio

This commentary aims to find the right description of the pre-reflective brain mechanisms underlying our phenomenal experience of being a subject bound to a physical body (bodily self) and basic cognitive, perceptual, and subjective aspects related to interaction with other individuals (social cognition). I will focus on the proposal by Gallese and Cuccio that embodied simulation, in terms of motor resonance, is the primary brain mechanism underlying the pre-reflective aspects of social cognition and the bodily self. I will argue that this proposal is too narrow to serve a unified theory of the neurobiological mechanisms of both target phenomena. I support this criticism with theoretical considerations and empirical evidence suggesting that multisensory spatial processing, which is distinct from but a pre-requisite of motor resonance, substantially contributes to the bodily self and social cognition. My commentary is structured in three sections. The first section addresses social cognition and compares embodied simulation to an alternative account, namely the attention schema theory. According to this theory we pre-reflectively empathize with others by predicting their current state of attention which involves predicting the spatial focus of attention. Thereby we derive a representational model of their state of mind. On this account, spatial coding of attention, rather than motor resonance, is the primary mechanism underlying social cognition. I take this as a theoretical alternative complementing motor resonance mechanisms. The second section focuses on the bodily self. Comparison of the brain networks of the bodily self and social cognition reveals strong overlap, suggesting that both phenomena depend on shared multisensory and sensorimotor mechanisms. I will review recent empirical data about altered states of the bodily self in terms of self-location and the first-person perspective. These spatial aspects of the bodily self are encoded in brain regions distinct from the brain network of embodied simulation. I argue that while motor resonance might contribute to body ownership and agency, it does not account for spatial aspects of the bodily self. Thus, embodied simulation appears to be a necessary but insufficiently “primary” brain mechanism of the bodily self and social cognition. The third section discusses the contributions of the vestibular system, i.e., the sensory system encoding head motion and gravity, to the bodily self and social cognition. Vestibular cortical processing seems relevant to both processes, because it directly encodes the world-centered direction of gravity and allows us to distinguish between motions of the own body and motions of other individuals and the external world. Furthermore, the vestibular cortical network largely overlaps with those neural networks relevant to the bodily self and social cognition. Thus, the vestibular system may play a crucial role in multisensory spatial coding relating the bodily self to other individuals in the external world

Human-Piloted Drone Racing: Visual Processing and Control

Humans race drones faster than algorithms, despite being limited to a fixed camera angle, body rate control, and response latencies in the order of hundreds of milliseconds. A better understanding of the ability of human pilots of selecting appropriate motor commands from highly dynamic visual information may provide key insights for solving current challenges in vision-based autonomous navigation. This paper investigates the relationship between human eye movements, control behavior, and flight performance in a drone racing task. We collected a multimodal dataset from 21 experienced drone pilots using a highly realistic drone racing simulator, also used to recruit professional pilots. Our results show task-specific improvements in drone racing performance over time. In particular, we found that eye gaze tracks future waypoints (i.e., gates), with first fixations occurring on average 1.5 seconds and 16 meters before reaching the gate. Moreover, human pilots consistently looked at the inside of the future flight path for lateral (i.e., left and right turns) and vertical maneuvers (i.e., ascending and descending). Finally, we found a strong correlation between pilots eye movements and the commanded direction of quadrotor flight, with an average visual-motor response latency of 220 ms. These results highlight the importance of coordinated eye movements in human-piloted drone racing. We make our dataset publicly available.Comment: 8 pages, 6 figure

Vision systems with the human in the loop

The emerging cognitive vision paradigm deals with vision systems that apply machine learning and automatic reasoning in order to learn from what they perceive. Cognitive vision systems can rate the relevance and consistency of newly acquired knowledge, they can adapt to their environment and thus will exhibit high robustness. This contribution presents vision systems that aim at flexibility and robustness. One is tailored for content-based image retrieval, the others are cognitive vision systems that constitute prototypes of visual active memories which evaluate, gather, and integrate contextual knowledge for visual analysis. All three systems are designed to interact with human users. After we will have discussed adaptive content-based image retrieval and object and action recognition in an office environment, the issue of assessing cognitive systems will be raised. Experiences from psychologically evaluated human-machine interactions will be reported and the promising potential of psychologically-based usability experiments will be stressed

ACCEPTANCE OF IMAGINED VERSUS EXPERIENCED VIRTUAL REALITY SHOPPING ENVIRONMENTS: INSIGHTS FROM TWO EXPERIMENTS

As first Virtual Reality (VR) shopping environments have begun to appear on the market, the question arises whether users will adopt them for doing their shopping. However, the evaluation of systems that have not yet diffused the market is potentially challenging because it requires bringing larger samples of respondents into a VR laboratory. Therefore, by conducting two experimental studies we shed light on the research question of whether evaluating the acceptance requires that respondents experience the immersive and interactive shopping environment. Our results reveal that particularly the hedonic variable perceived enjoyment as well as the VR specific variable perceived telepresence are underestimated when participants only imagine (based on a video) being in a VR shopping environment while there is no difference with respect to the behavioral intention to use the system. In addition, we show that particularly the hedonic variable perceived enjoyment and the utilitarian variable perceived usefulness influence the intention to use the shopping environment in the future. Overall, we conclude that experiencing the VR shopping environment is essential for users to be able to evaluate the respective technology

Zur Entwicklung der Gewalt in Deutschland : Schwerpunkte: Jugendliche und Flüchtlinge als Täter und Opfer

Unter Mitarbeit von Prof. Dr. Thomas Mößle, Laura Beckmann und Eberhard Mecklenbur