Gesamtliste aus der Hochschulbibliographie

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Machts, René; Hunold, Alexander; Drebenstedt, Christian; Rock, Michael; Leu, Carsten; Haueisen, Jens
Rain may improve survival from direct lightning strikes to the human head. - In: Scientific reports, ISSN 2045-2322, Bd. 14 (2024), 1, 1695, S. 1-9

There is evidence that humans can survive a direct lightning strike to the head. Our question is: could water (rain) on the skin contribute to an increase in the survival rate? We measure the influence of rain during high-energy direct lightning strikes on a realistic three-compartment human head phantom. We find a lower number of perforations and eroded areas near the lightning strike impact points on the head phantom when rain was applied compared to no rain. Current amplitudes in the brain were lower with rain compared to no rain before a fully formed flashover. We conclude that rain on the scalp potentially contributes to the survival rate of 70-90% due to: (1) lower current exposition in the brain before a fully formed flashover, and (2) reduced mechanical and thermal damage.



https://doi.org/10.1038/s41598-023-50563-w
Mühlenhoff, Julian; Radler, Oliver; Sattel, Thomas
Development of a hydraulic actuator for MRI- and radiation-compatible medical applications. - In: Actuators, ISSN 2076-0825, Bd. 13 (2024), 3, 90, S. 1-17

This paper presents methods for the actuation, measurement, and control of a magnetic resonance imaging- and radiation-compatible single-axis translatory actuation system. As an exemplary demanding use case, the axis is developed for a robotic phantom for evaluating emitted radiation doses of radiotherapy devices. For this, the robot has to follow given three-dimensional trajectories of patients’ movements with an accuracy of 200 µm. For enabling use of magnetic resonance imaging, actuation of the robot is realized by hydraulic transmission without any metal parts or electrical components at the imaging side. The hydraulic axis is developed, built-up, and tested. In order to compensate for deviations from the targeted actuation trajectory resulting from tolerances, friction, and non-linearities in the system, a combination of photogrammetric measurement and iterative learning control is applied. The developed photogrammetric system is capable of determining the robot’s position with systematic errors of 35 µm and stochastic errors of 0.3 µm. Different types of iterative learning control methods are applied, parameterized, and tested. With this, the hydraulically actuated axis is able to follow given trajectories with maximum errors below 130 µm.



https://doi.org/10.3390/act13030090
Chu, Xu; Pandey, Sandeep
Non-intrusive, transferable model for coupled turbulent channel-porous media flow based upon neural networks. - In: Physics of fluids, ISSN 1089-7666, Bd. 36 (2024), 2, 025112, S. 025112-1-025112-13

Turbulent flow over permeable interfaces is omnipresent featuring complex flow topology. In this work, a data-driven, end-to-end machine learning model has been developed to model the turbulent flow in porous media. For the same, we have derived a non-linear reduced order model (ROM) with a deep convolution autoencoder. This model can reduce highly resolved spatial dimensions, which is a prerequisite for direct numerical simulation, by 99%. A downstream recurrent neural network has been trained to capture the temporal trend of reduced modes; thus, it is able to provide future evolution of modes. We further evaluate the trained model's capability on a newer dataset with a different porosity. In such cases, fine-tuning could reduce the efforts (up to two-order of magnitude) to train a model with limited dataset (10%) and knowledge and still show a good agreement on the mean velocity profile. Especially, the fine-tuned model shows a better agreement in the porous domain than the channel and interface areas indicating the topological feature is less challenging for training than the multi-scale nature of the turbulent flows. Leveraging the current model, we find that even quick fine-tuning achieves an impressive order-of-magnitude reduction in training time by approximately O(102) and still results in effective flow predictions. This promising discovery encourages the fast development of a substantial amount of data-driven models tailored for various types of porous media. The diminished training time substantially lowers the computational cost when dealing with changing porous topologies, making it feasible to systematically explore interface engineering with different types of porous media.



https://doi.org/10.1063/5.0189632
Schwarz, Andreas; Sellnow, Timothy L.; Geppert, Johanna; Sellnow, Deanna D.
Protective action as an enduring keystone of risk communication: effective form, function and process of risk messaging as advocated by global higher education practitioners during a pandemic. - In: Journal of contingencies and crisis management, ISSN 1468-5973, Bd. 32 (2024), 1, e12545, S. 1-6

Risk communication is a keystone in crisis prevention and mitigation. For that purpose, many institutions worldwide have the task of translating scientific risk information into actionable messages for public safety. As a collaboration among international risk and crisis communication scholars and practitioners, we sought to identify what risk communication practitioners at higher education organizations in the Global South and North identify as essential elements of effective risk communication, based on 32 interviews in 16 countries during the first wave of the COVID-19 pandemic (June-August, 2020). Results exemplify a shared vision for addressing the stickiest, most wicked challenges to effective risk communication globally. The interviews revealed globally shared best practices related to form, function, and process leading directly to what we consider the keystone of effective risk communication: saving lives (outcome).



https://doi.org/10.1111/1468-5973.12545
Gholamhosseinian, Ashkan; Seitz, Jochen
CAI2M2: a centralized autonomous inclusive intersection management mechanism for heterogeneous connected vehicles. - In: IEEE open journal of vehicular technology, ISSN 2644-1330, Bd. 5 (2024), S. 230-243

https://doi.org/10.1109/OJVT.2024.3354393
Dong, Yulian; Huo, Jingyao; Xu, Changfan; Ji, Deyang; Zhao, Huaping; Li, Liqiang; Lei, Yong
Research progress on vanadium sulfide anode materials for sodium and potassium-ion batteries. - In: Advanced Materials Technologies, ISSN 2365-709X, Bd. n/a (2024), n/a, 2301840, S. 1-28

Considering environmental changes and the demand for more sustainable energy sources, stricter requirements have been placed on electrode materials for sodium and potassium-ion batteries, which are expected to provide higher energy and power density while being affordable and sustainable. Vanadium sulfide-based materials have emerged as intriguing contenders for the next generation of anode materials due to their high theoretical capacity, abundant reserves, and cost-effectiveness. Despite these advantages, challenges such as limited cycle life and restricted ion diffusion coefficients continue to impede their effective application in sodium and potassium-ion batteries. To overcome the limitations associated with electrochemical performance and circumvent bottlenecks imposed by the inherent properties of materials at the bulk scale, this review comprehensively summarizes and analyzes the crystal structures, modification strategies, and energy storage processes of vanadium sulfide-based electrode materials for sodium and potassium-ion batteries. The objective is to guide the development of high-performance vanadium-based sulfide electrode materials with refined morphologies and/or structures, employing environmentally friendly and cost-efficient methods. Finally, future perspectives and research suggestions for vanadium sulfide-based materials are presented to propel practical applications forward.



https://doi.org/10.1002/admt.202301840
Küstner, Merle Johanna; Eckstein, Diana; Brauer, Dana; Mai, Patrick; Hampl, Jörg; Weise, Frank; Schuhmann, Berit; Hause, Gerd; Glahn, Felix; Foth, Heidi; Schober, Andreas
Modular air-liquid interface aerosol exposure system (MALIES) to study toxicity of nanoparticle aerosols in 3D-cultured A549 cells in vitro. - In: Archives of toxicology, ISSN 1432-0738, Bd. 0 (2024), 0, insges. 20 S.

We present a novel lung aerosol exposure system named MALIES (modular air-liquid interface exposure system), which allows three-dimensional cultivation of lung epithelial cells in alveolar-like scaffolds (MatriGrids®) and exposure to nanoparticle aerosols. MALIES consists of multiple modular units for aerosol generation, and can be rapidly assembled and commissioned. The MALIES system was proven for its ability to reliably produce a dose-dependent toxicity in A549 cells using CuSO4 aerosol. Cytotoxic effects of BaSO4- and TiO2-nanoparticles were investigated using MALIES with the human lung tumor cell line A549 cultured at the air-liquid interface. Experiments with concentrations of up to 5.93 × 10^5 (BaSO4) and 1.49 × 10^6 (TiO2) particles/cm^3, resulting in deposited masses of up to 26.6 and 74.0 µg/cm^2 were performed using two identical aerosol exposure systems in two different laboratories. LDH, resazurin reduction and total glutathione were measured. A549 cells grown on MatriGrids® form a ZO-1- and E-Cadherin-positive epithelial barrier and produce mucin and surfactant protein. BaSO4-NP in a deposited mass of up to 26.6 µg/cm^2 resulted in mild, reversible damage (˜ 10% decrease in viability) to lung epithelium 24 h after exposure. TiO2-NP in a deposited mass of up to 74.0 µg/cm^2 did not induce any cytotoxicity in A549 cells 24 h and 72 h after exposure, with the exception of a 1.7 fold increase in the low exposure group in laboratory 1. These results are consistent with previous studies showing no significant damage to lung epithelium by short-term treatment with low concentrations of nanoscale BaSO4 and TiO2 in in vitro experiments.



https://doi.org/10.1007/s00204-023-03673-3
Sarısakalo&bovko;glu, Aynur;
[Rezension von: Schlüsselwerke der Journalismusforschung]. - In: Publizistik. - Wiesbaden : VS Verl. für Sozialwiss., 2000- , ISSN: 1862-2569 , ZDB-ID: 2273951-8Publizistik, ISSN 1862-2569, Bd. 0 (2024), 0, insges. 3 S.

https://doi.org/10.1007/s11616-023-00827-2
Koch, Juliane; Liborius, Lisa; Kleinschmidt, Peter; Prost, Werner; Weimann, Nils; Hannappel, Thomas
Impact of the tip-to-semiconductor contact in the electrical characterization of nanowires. - In: ACS omega, ISSN 2470-1343, Bd. 9 (2024), 5, S. 5788-5797

Well-defined semiconductor heterostructures are a basic requirement for the development of high-performance optoelectronic devices. In order to achieve the desired properties, a thorough study of the electrical behavior with a suitable spatial resolution is essential. For this, various sophisticated tip-based methods can be employed, such as conductive atomic force microscopy or multitip scanning tunneling microscopy (MT-STM). We demonstrate that in any tip-based measurement method, the tip-to-semiconductor contact is decisive for reliable and precise measurements and in interpreting the properties of the sample. For that, we used our ultrahigh-vacuum-based MT-STM coupled in vacuo to a reactor for the preparation of nanowires (NWs) with metal organic vapor phase epitaxy, and operated our MT-STM as a four-point nanoprober on III-V semiconductor NW heterostructures. We investigated a variety of upright, free-standing NWs with axial as well as coaxial heterostructures on the growth substrates. Our investigation reveals charging currents at the interface between the measuring tip and the semiconductor via native insulating oxide layers, which act as a metal-insulator-semiconductor capacitor with charging and discharging conditions in the operating voltage range. We analyze in detail the observed I-V characteristics and propose a strategy to achieve an optimized tip-to-semiconductor junction, which includes the influence of the native oxide layer on the overall electrical measurements. Our advanced experimental procedure enables a direct relation between the tip-to-NW junction and the electronic properties of as-grown (co)axial NWs providing precise guidance for all future tip-based investigations.



https://doi.org/10.1021/acsomega.3c08729
Li, Zirui; Faheem, Faizan; Husung, Stephan
Collaborative Model-based Systems Engineering using Dataspaces and SysML v2. - In: Systems, ISSN 2079-8954, Bd. 12 (2024), 1, 18, S. 1-22

Collaborative Model-based Systems Engineering between companies is becoming increasingly important. The utilization of the modeling possibilities of the standard language SysML v2 and the multilateral data exchange via Dataspaces open new possibilities for efficient collaboration. Based on systemic approaches, a modeling concept for decomposing the system into sub-systems is developed as a basis for the exchange. In addition, based on the analysis of collaboration processes in the context of Systems Engineering, an architectural approach with a SysML editor and Dataspace for the exchange is elaborated. The architecture is implemented on the basis of open-source solutions. The investigations are based on an application example from precision engineering. The potential and challenges are discussed.



https://doi.org/10.3390/systems12010018