Complete list from the university bibliography

Anzahl der Treffer: 464
Erstellt: Wed, 27 Mar 2024 23:38:05 +0100 in 0.0666 sec


Boeck, Thomas;
Stability analysis of wall-attached Bénard-Marangoni convection in a vertical magnetic field. - In: Proceedings in applied mathematics and mechanics, ISSN 1617-7061, Bd. 23 (2023), 2, e202300020, S. 1-8

The threshold for the onset of thermocapillary flow in a planar liquid layer heated from below is increased by a vertical magnetic field when the liquid is a good electric conductor. The magnetic damping effect is reduced when the induced eddy currents are blocked by insulating side walls. Neutral conditions for this specific Bénard-Marangoni stability problem with a vertical field and side walls are obtained numerically for three-dimensional perturbations assumed periodic in one horizontal direction. The domain is bounded by a free-slip wall at the bottom, a free surface at the top and two free-slip lateral walls in the other horizontal direction. Buoyancy forces and surface deformations are neglected and a constant heat flux is imposed on the free surface. Upon increasing the magnetic induction, the least stable modes become localized near the side walls and the convective threshold increases at a lower rate than for the least stable bulk mode.



https://doi.org/10.1002/pamm.202300020
Omidian, Maryam; Schulte, Stefan; Néel, Nicolas; Kröger, Jörg
Scanning tunneling spectroscopy of lithium-decorated graphene. - In: Annalen der Physik, ISSN 1521-3889, Bd. 535 (2023), 11, 2300249, S. 1-8

Lithium decoration of graphene on SiC(0001) is achieved in a surface science approach by intercalation and adsorption of the alkali metal. Spectroscopy of the differential conductance with a scanning tunneling microscope at the Li-decorated graphene surfaces does not give rise to a pairing gap at the Fermi energy, which may be expected because of the previously predicted superconducting phase [Profeta et al., Nat. Phys. 2012, 8, 131]. Rather, pronounced gaps in the spectroscopic data of intercalated samples reflect the excitation of graphene phonons. Rationales that possibly explain this discrepancy between experimental findings and theoretical predictions are suggested.



https://doi.org/10.1002/andp.202300249
Schindler, Max; Domahidi, Emese
Exploring citizen discussions’ potential to inform smart city agendas: insights from German-city-centered online communities. - In: New media & society, ISSN 1461-7315, Bd. 0 (2023), 0

With more than 50% of the world’s population living in urban areas, the smart city concept has been introduced as a solution to urbanization problems, with a focus on technological and social innovation. However, critics argue that the concept is more about marketing than actual benefits for citizens. Given the limitations of conventional and formalized e-participation and smart city procedures, we highlight the value of shared citizen knowledge and the potential of e-interaction in this context by analyzing city-related informal social media communication, following recent calls to embrace citizens’ opinions in the smart city framework. This work focuses on major German cities with more than 100,000 inhabitants. The authors identify nine categories of interest in citizens’ discussions. Unlike official channels, citizens tend to focus on social and societal issues. The results of this study can complement existing tools by including citizens’ perspectives in smart city decision-making processes.



https://doi.org/10.1177/14614448231187032
Samadi, Raheleh; Nazari, Amin; Seitz, Jochen
Intelligent Energy-aware Routing Protocol in Mobile IoT Networks based on SDN. - In: IEEE transactions on green communications and networking, ISSN 2473-2400, Bd. 7 (2023), 4, S. 2093-2103

Intelligent devices and equipment have affected almost all aspects of our life and behavior. The type of connection and the manner of communication between this large volume of devices has caused the emergence of a vast field in the Internet called the Internet of Things, which significantly highlights the issue of energy management and increases the lifetime of networks. Complex communications, especially in mobile networks, have generated many challenges for network designers. To solve these challenges, the Software Defined Networking (SDN) paradigm has reduced the overhead in the devices caused by processing and computing by adding new capabilities to mobile IoT networks. This technique transfers energy-consuming tasks to the central controller, which manages continuous topological changes of the network in dynamic environments. This paper presents a new routing approach called Intelligent Energy-aware Routing Protocol in Mobile IoT Networks based on SDN (IERMIoT), which tries to manage the dynamic changes of topology due to the movement of mobile nodes to increase the network’s lifetime and prevent energy dissipation. For this purpose, it defines clusters of nodes and uses an intelligent evolutionary algorithm to determine the number of clusters required in the network and their balanced distribution in the dynamic environment. Also, this approach considers a mechanism to reduce the overhead of control packets and routing packets, which significantly affects the energy consumption of nodes. The simulation results indicate the proposed solution’s effectiveness compared to other simulated approaches with respect to packet delivery rate, average energy consumption, network lifetime, number of alive nodes, coverage, and routing overhead.



https://doi.org/10.1109/TGCN.2023.3296272
Arlt, Dorothee; Schumann, Christina; Wolling, Jens
What does the public know about technological solutions for achieving carbon neutrality? Citizens' knowledge of energy transition and the role of media. - In: Frontiers in communication, ISSN 2297-900X, Bd. 8 (2023), 1005603, S. 01-13

The present study explores the relation between media use and knowledge in the context of the energy transition. To identify relevant knowledge categories, we relied on the expertise of an interdisciplinary research team. Based on this expertise, we identified awareness-knowledge of changes in the energy system and principles-knowledge of hydrogen as important knowledge categories. With data obtained from a nationwide online survey of the German-speaking population (n = 2,025) conducted in August 2021, we examined the level of knowledge concerning both categories in the German population. Furthermore, we studied its associations with exposure to journalistic media and direct communication from non-media actors (e.g., scientists). Our results revealed a considerable lack of knowledge for both categories. Considering the media variables, we found only weak, and in some cases even negative, relations with the use of journalistic media or other actors that spread information online. However, we found comparably strong associations between both knowledge categories and the control variables of sex, education, and personal interest. We use these results to open up a general discussion of the role of the media in knowledge acquisition processes.



https://www.frontiersin.org/articles/10.3389/fcomm.2023.1005603
Ran, Yan; Ren, Jie; Yang, Zhi Chao; Zhao, Huaping; Wang, Yude; Lei, Yong
The 3D flower-like MnV12O31&hahog;10H2O as a high-capacity and long-lifespan cathode material for aqueous zinc-ion batteries. - In: Small structures, ISSN 2688-4062, Bd. 4 (2023), 11, 2300136, S. 1-11

Selecting the right cathode material is a key component to achieving high-energy and long-lifespan aqueous zinc-ion batteries (AZIBs); however, the development of cathode materials still faces serious challenges due to the high polarization of Zn2+. In this work, MnV12O31&hahog;10H2O (MnVO) synthesized via a one-step hydrothermal method is proposed as a promising cathode material for AZIBs. Because the stable layered structure and hieratical morphology of MnVO provide a large layer space for rapid ion transports, this material exhibits high specific capacity (433 mAh g−1 at 0.1 A g−1), an outstanding long-term cyclability (5000 cycles at a current density of 3 A g−1), and an excellent energy density (454.65 Wh kg−1). To illustrate the intercalation mechanism, ex situ X-Ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy are adopted, uncovering an H+/Zn2+ dual-cation co-intercalation processes. In addition, density-functional theory calculation analysis shows that MnVO has a delocalized electron cloud and the diffusion energy barrier of Zn2+ in MnVO is low, which promotes the Zn2+ transport and consequently improves the reversibility of the battery upon deep cycling. The key and enlightening insights are provided in the results for designing high-performance vanadium-oxide-based cathode materials for AZIBs.



https://doi.org/10.1002/sstr.202300136
Jochmann, Thomas; Seibel, Marc S.; Jochmann, Elisabeth; Khan, Sheraz; Hämäläinen, Matti; Haueisen, Jens
Sex-related patterns in the electroencephalogram and their relevance in machine learning classifiers. - In: Human brain mapping, ISSN 1097-0193, Bd. 44 (2023), 14, S. 4848-4858

Deep learning is increasingly being proposed for detecting neurological and psychiatric diseases from electroencephalogram (EEG) data but the method is prone to inadvertently incorporate biases from training data and exploit illegitimate patterns. The recent demonstration that deep learning can detect the sex from EEG implies potential sex-related biases in deep learning-based disease detectors for the many diseases with unequal prevalence between males and females. In this work, we present the male- and female-typical patterns used by a convolutional neural network that detects the sex from clinical EEG (81% accuracy in a separate test set with 142 patients). We considered neural sources, anatomical differences, and non-neural artifacts as sources of differences in the EEG curves. Using EEGs from 1140 patients, we found electrocardiac artifacts to be leaking into the supposedly brain activity-based classifiers. Nevertheless, the sex remained detectable after rejecting heart-related and other artifacts. In the cleaned data, EEG topographies were critical to detect the sex, but waveforms and frequencies were not. None of the traditional frequency bands was particularly important for sex detection. We were able to determine the sex even from EEGs with shuffled time points and therewith completely destroyed waveforms. Researchers should consider neural and non-neural sources as potential origins of sex differences in their data, they should maintain best practices of artifact rejection, even when datasets are large, and they should test their classifiers for sex biases.



https://doi.org/10.1002/hbm.26417
Junger, Christina; Buch, Benjamin; Notni, Gunther
Triangle-Mesh-Rasterization-Projection (TMRP): an algorithm to project a point cloud onto a consistent, dense and accurate 2D raster image. - In: Sensors, ISSN 1424-8220, Bd. 23 (2023), 16, 7030, S. 1-28

The projection of a point cloud onto a 2D camera image is relevant in the case of various image analysis and enhancement tasks, e.g., (i) in multimodal image processing for data fusion, (ii) in robotic applications and in scene analysis, and (iii) for deep neural networks to generate real datasets with ground truth. The challenges of the current single-shot projection methods, such as simple state-of-the-art projection, conventional, polygon, and deep learning-based upsampling methods or closed source SDK functions of low-cost depth cameras, have been identified. We developed a new way to project point clouds onto a dense, accurate 2D raster image, called Triangle-Mesh-Rasterization-Projection (TMRP). The only gaps that the 2D image still contains with our method are valid gaps that result from the physical limits of the capturing cameras. Dense accuracy is achieved by simultaneously using the 2D neighborhood information (rx,ry) of the 3D coordinates in addition to the points P(X,Y,V). In this way, a fast triangulation interpolation can be performed. The interpolation weights are determined using sub-triangles. Compared to single-shot methods, our algorithm is able to solve the following challenges. This means that: (1) no false gaps or false neighborhoods are generated, (2) the density is XYZ independent, and (3) ambiguities are eliminated. Our TMRP method is also open source, freely available on GitHub, and can be applied to almost any sensor or modality. We also demonstrate the usefulness of our method with four use cases by using the KITTI-2012 dataset or sensors with different modalities. Our goal is to improve recognition tasks and processing optimization in the perception of transparent objects for robotic manufacturing processes.



https://doi.org/10.3390/s23167030
Jaekel, Konrad; Sauni Camposano, Yesenia Haydee; Matthes, Sebastian; Glaser, Marcus; Schaaf, Peter; Bergmann, Jean Pierre; Müller, Jens; Bartsch, Heike
Ni/Al multilayer reactions on nanostructured silicon substrates. - In: Journal of materials science, ISSN 1573-4803, Bd. 58 (2023), 31, S. 12811-12826

Fast energy release, which is a fundamental property of reactive multilayer systems, can be used in a wide field of applications. For most applications, a self-propagating reaction and adhesion between the multilayers and substrate are necessary. In this work, a distinct approach for achieving self-propagating reactions and adhesion between deposited Ni/Al reactive multilayers and silicon substrate is demonstrated. The silicon surface consists of random structures, referred to as silicon grass, which were created by deep reactive ion etching. Using the etching process, structure units of heights between 8 and 13 µm and density between 0.5 and 3.5 structures per µm^2 were formed. Ni and Al layers were alternatingly deposited in the stoichiometric ratio of 1:1 using sputtering, to achieve a total thickness of 5 µm. The analysis of the reaction and phase transformation was done with high-speed camera, high-speed pyrometer, and X-ray diffractometer. Cross-sectional analysis showed that the multilayers grew only on top of the silicon grass in the form of inversed cones, which enabled adhesion between the silicon grass and the reacted multilayers. A self-propagating reaction on silicon grass was achieved, due to the thermally isolating air pockets present around these multilayer cones. The velocity and temperature of the reaction varied according to the structure morphology. The reaction parameters decreased with increasing height and decreasing density of the structures. To analyze the exact influence of the morphology, further investigations are needed.



https://doi.org/10.1007/s10853-023-08794-9
Eichfelder, Gabriele; Warnow, Leo
A hybrid patch decomposition approach to compute an enclosure for multi-objective mixed-integer convex optimization problems. - In: Mathematical methods of operations research, ISSN 1432-5217, Bd. 0 (2023), 0, insges. 30 S.

In multi-objective mixed-integer convex optimization, multiple convex objective functions need to be optimized simultaneously while some of the variables are restricted to take integer values. In this paper, we present a new algorithm to compute an enclosure of the nondominated set of such optimization problems. More precisely, we decompose the multi-objective mixed-integer convex optimization problem into several multi-objective continuous convex optimization problems, which we refer to as patches. We then dynamically compute and improve coverages of the nondominated sets of those patches to finally combine them to obtain an enclosure of the nondominated set of the multi-objective mixed-integer convex optimization problem. Additionally, we introduce a mechanism to reduce the number of patches that need to be considered in total. Our new algorithm is the first of its kind and guaranteed to return an enclosure of prescribed quality within a finite number of iterations. For selected numerical test instances we compare our new criterion space based approach to other algorithms from the literature and show that much larger instances can be solved with our new algorithm.



https://doi.org/10.1007/s00186-023-00828-x