Gesamtliste aus der Hochschulbibliographie

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Yan, Chengzhan; Chao, Xin; Zhao, Huaping; Wang, Shun; Lei, Yong
Synthesis of nitrogen-doped amorphous carbon nanotubes from novel cobalt-based MOF precursors for improving potassium-ion storage capability. - In: , ISSN 1095-7103, Bd. 677 (2025), 1, S. 35-44

Amorphous carbon materials with sophisticated morphologies, variable carbon layer structures, abundant defects, and tunable porosities are favorable as anodes for potassium-ion batteries (PIBs). Synthesizing amorphous carbon materials typically involves the pyrolysis of carbonaceous precursors. Nonetheless, there is still a lack of studies focused on achieving multifaceted structural optimizations of amorphous carbon through precursor formulation. Herein, nitrogen-doped amorphous carbon nanotubes (NACNTs) are derived from a novel composite precursor of cobalt-based metal-organic framework (CMOF) and graphitic carbon nitride (g-CN). The addition of g-CN in the precursor optimizes the structure of amorphous carbon such as morphology, interlayer spacing, nitrogen doping, and porosity. As a result, NACNTs demonstrate significantly improved electrochemical performance. The specific capacities of NACNTs after cycling at current densities of 100 mA/g and 1000 mA/g increased by 194 % and 230 %, reaching 346.6 mAh/g and 211.8 mAh/g, respectively. Furthermore, the NACNTs anode is matched with an organic cathode for full-cell evaluation. The full-cell attains a high specific capacity of 106 mAh/gcathode at a current density of 100 mA/g, retaining 90.5 % of the specific capacity of the cathode half-cell. This study provides a valuable reference for multifaceted structural optimization of amorphous carbon to improve potassium-ion storage capability.



https://doi.org/10.1016/j.jcis.2024.07.191
Liao, Wang; Zhang, Chen; Aliâc, Belmin; Wildenauer, Alina; Dietz-Terjung, Sarah; Sucre, Jose Guillermo Ortiz; Sutharsan, Sivagurunathan; Schöbel, Christoph; Seidl, Karsten; Notni, Gunther
Leveraging 3D convolutional neural network and 3D visible-near-infrared multimodal imaging for enhanced contactless oximetry. - In: Journal of biomedical optics, ISSN 1560-2281, Bd. 29 (2024), S3, S33309, S. S33309-1-S33309-20

Significance: Monitoring oxygen saturation (SpO2) is important in healthcare, especially for diagnosing and managing pulmonary diseases. Non-contact approaches broaden the potential applications of SpO2 measurement by better hygiene, comfort, and capability for long-term monitoring. However, existing studies often encounter challenges such as lower signal-to-noise ratios and stringent environmental conditions. Aim: We aim to develop and validate a contactless SpO2 measurement approach using 3D convolutional neural networks (3D CNN) and 3D visible-near-infrared (VIS-NIR) multimodal imaging, to offer a convenient, accurate, and robust alternative for SpO2 monitoring. Approach: We propose an approach that utilizes a 3D VIS-NIR multimodal camera system to capture facial videos, in which SpO2 is estimated through 3D CNN by simultaneously extracting spatial and temporal features. Our approach includes registration of multimodal images, tracking of the 3D region of interest, spatial and temporal preprocessing, and 3D CNN-based feature extraction and SpO2 regression. Results: In a breath-holding experiment involving 23 healthy participants, we obtained multimodal video data with reference SpO2 values ranging from 80% to 99% measured by pulse oximeter on the fingertip. The approach achieved a mean absolute error (MAE) of 2.31% and a Pearson correlation coefficient of 0.64 in the experiment, demonstrating good agreement with traditional pulse oximetry. The discrepancy of estimated SpO2 values was within 3% of the reference SpO2 for ∼80% of all 1-s time points. Besides, in clinical trials involving patients with sleep apnea syndrome, our approach demonstrated robust performance, with an MAE of less than 2% in SpO2 estimations compared to gold-standard polysomnography. Conclusions: The proposed approach offers a promising alternative for non-contact oxygen saturation measurement with good sensitivity to desaturation, showing potential for applications in clinical settings.



https://doi.org/10.1117/1.JBO.29.S3.S33309
Lanza, Lukas;
Exact output tracking in prescribed finite time via funnel control. - In: Automatica, ISSN 0005-1098, Bd. 170 (2024), 111873, S. 1-9

Output reference tracking of unknown nonlinear systems is considered. The control objective is exact tracking in predefined finite time, while in the transient phase the tracking error evolves within a prescribed boundary. To achieve this, a novel high-gain feedback controller is developed that is similar to, but extends, existing high-gain feedback controllers. Feasibility and functioning of the proposed controller is proven rigorously. Examples for the particular control objective under consideration are, for instance, linking up two train sections, or docking of spaceships.



https://doi.org/10.1016/j.automatica.2024.111873
Zhang, Xijie;
Is open access disrupting the journal business? : a perspective from comparing full adopters, partial adopters, and non-adopters. - In: Journal of informetrics, ISSN 1751-1577, Bd. 18 (2024), 4, 101574, S. 1-14

Two decades after the inception of open access publishing (OA), its impact has remained a focal point in academic discourse. This study adopted a disruptive innovation framework to examine OA's influence on the traditional subscription market. It assesses the market power of gold journals (OA full adopters) in comparison with hybrid journals and closed-access journals (partial adopters and non-adopters). Additionally, it contrasts the market power between hybrid journals (partial adopters) and closed-access journals (non-adopters). Using the Lerner index to measure market power through price elasticity of demand, this study employs difference tests and multiple regressions. These findings indicate that OA full adopters disrupt the market power of non-adopting incumbents. However, by integrating the OA option into their business models, partial adopters can effectively mitigate this disruption and expand their influence from the traditional subscription market to the emerging OA paradigm.



https://doi.org/10.1016/j.joi.2024.101574
Engelhardt, Maximilian; Giehl, Sebastian; Schubert, Michael; Ihlow, Alexander; Schneider, Christian; Ebert, Alexander; Landmann, Markus; Del Galdo, Giovanni; Andrich, Carsten
Accelerating innovation in 6G research: real-time capable SDR system architecture for rapid prototyping. - In: IEEE access, ISSN 2169-3536, Bd. 12 (2024), S. 118718-118732

The upcoming 3GPP global mobile communication standard 6G strives to push the technological limits of radio frequency (RF) communication even further than its predecessors: Sum data rates beyond 100 Gbit/s, RF bandwidths above 1 GHz per link, and sub-millisecond latency necessitate very high performance development tools. We propose a new SDR firmware and software architecture designed explicitly to meet these challenging requirements. It relies on Ethernet and commercial off-the-shelf network and server components to maximize flexibility and to reduce costs. We analyze state-of-the-art solutions (USRP X440 and other RFSoC-based systems), derive architectural design goals, explain resulting design decision in detail, and exemplify our architecture’s implementation on the XCZU48DR RFSoC. Finally, we validate its performance via measurements and outline how the architecture surpasses the state of the art with respect to sustained RF recording, while maintaining high Ethernet bandwidth efficiency. Building a 6G integrated sensing and communication (ISAC) example, we demonstrate its real-time and rapid application development capabilities.



https://doi.org/10.1109/ACCESS.2024.3447884
Peh, Katharina; Bratek, Dominik; Lauer, Kevin; Müller, Robin Lars Benedikt; Schulze, Dirk; Flötotto, Aaron; Krischok, Stefan
Light-induced degradation transition energy barrier measured by photoluminescence spectra in Si:In. - In: Physica status solidi, ISSN 1862-6319, Bd. 0 (2024), 0, 2400570, S. 1-7

https://doi.org/10.1002/pssa.202400570
Zheng, Niannian; Shardt, Yuri A. W.; Luan, Xiaoli; Liu, Fei
Supervised probabilistic dynamic-controlled latent-variable model for quality pattern prediction and optimisation. - In: ISA transactions, ISSN 1879-2022, Bd. 0 (2024), 0, S. 1-19

A supervised probabilistic dynamic-controlled latent-variable (SPDCLV) model is proposed for online prediction, as well as real-time optimisation of process quality indicators. Compared to existing probabilistic latent-variable models, the key advantage of the proposed method lies in explicitly modelling the dynamic causality from the manipulated inputs to the quality pattern. This is achieved using a well-designed, dynamic-controlled Bayesian network. Furthermore, the algorithms for expectation-maximisation, forward filtering, and backward smoothing are designed for learning the SPDCLV model. For engineering applications, a framework for pattern-based quality prediction and optimisation is proposed, under which the pattern-filtering and pattern-based soft sensor are explored for online quality prediction. Furthermore, quality optimisation can be realised by directly controlling the pattern to the desired condition. Finally, case studies on both an industrial primary milling circuit and a numerical example illustrate the benefits of the SPDCLV method in that it can fully model the process dynamics, effectively predict and optimise the quality indicators, and monitor the process.



https://doi.org/10.1016/j.isatra.2024.08.001
Bohlemann, Chris Yannic; Flötotto, Aaron; Paszuk, Agnieszka; Nandy, Manali; Großmann, Max; Romanyuk, Oleksandr; Hanke, Kai Daniel; Gieß, Aaron; Kleinschmidt, Peter; Runge, Erich; Hannappel, Thomas
Surface structure of MOVPE-prepared As-modified Si(100) substrates. - In: Applied surface science, Bd. 675 (2024), 160879, S. 1-8

In the pursuit of high-efficiency tandem devices for solar energy conversion based on III-V-semiconductors, low-defect III-V nucleation on Si(100) substrates is essential. Here, hydrogen and arsenic are key ingredients in all growth processes with respect to industrially scalable metalorganic vapor phase epitaxy. Our study provides insight into Si(100) surface preparation for the initial stage of III-V nucleation. The samples investigated, prepared on substrates with different offcut angles, show single domain surfaces consisting of rows of preferentially buckled dimers. Low energy electron diffraction and reflection anisotropy spectroscopy confirm well-defined (1 × 2)/(2 × 1) majority domains. Fourier-transform infrared spectroscopy revealed hydrogen bonding to the surface dimers, while no impurities were found by XPS. Density functional theory calculations support the experimental results and reveal a novel surface motif of H-passivated Si-As mixed dimers.



https://doi.org/10.1016/j.apsusc.2024.160879
Oppeneiger, Benedikt; Lanza, Lukas; Schell, Maximilian; Dennstädt, Dario; Schaller, Manuel; Zamzow, Bert; Berger, Thomas; Worthmann, Karl
Model predictive control of a magnetic levitation system with prescribed output tracking performance. - In: Control engineering practice, ISSN 1873-6939, Bd. 151 (2024), 106018, S. 1-14

To guarantee the safe and dependable operation of a magnetic levitation train, the distance between the magnet and the reaction rail needs to be kept within a given range. In this work, we design model predictive controllers which, in addition to complying with these constraints, provide a favorable behavior with regard to performance criteria such as travel comfort and control effort. For this purpose, we present a model of the system and the disturbances affecting it. Several results regarding the mathematical properties of this model are proven to gain insight for controller design. Finally we compare three different controllers w.r.t. performance criteria such as robustness, travel comfort, control effort, and computation time in an extensive numerical simulation study: a linear feedback controller, a model predictive control (MPC) scheme with quadratic stage costs, and the recently-proposed funnel MPC scheme. We show that the MPC closed loop complies with the constraints while also exhibiting excellent performance. Furthermore, we implement the MPC algorithms within the GRAMPC framework. This allows us to reduce the computational effort to a point at which real-time application becomes feasible.



https://doi.org/10.1016/j.conengprac.2024.106018
Lauer, Kevin; Reiß, Stephanie; Flötotto, Aaron; Peh, Katharina; Bratek, Dominik; Müller, Robin; Schulze, Dirk; Beenken, Wichard J. D.; Hiller, Erik; Ortlepp, Thomas; Krischok, Stefan
Effect of inelastic ion collisions on low-gain avalanche detectors explained by an ASi-Sii-defect mode. - In: Nuclear instruments & methods in physics research, Bd. 555 (2024), 165472, S. 1-5

The acceptor removal phenomenon (ARP), which hampers the functionality of low-gain avalanche detectors (LGAD), is discussed in frame of the ASi-Sii-defect model. The assumption of fast diffusion of interstitial silicon is shown to be superfluous for the explanation of the BSi-Sii-defect formation under irradiation, particular at very low temperatures. The experimentally observed properties of the ARP are explained by the donor properties of the BSi-Sii-defect in its ground state. Additionally, low temperature photoluminescence spectra are reported for quenched boron doped silicon showing so far unidentified PL lines, which change due to well-known light-induced degradation (LID) treatments.



https://doi.org/10.1016/j.nimb.2024.165472