Konferenzbeiträge ab 2018 bis 2021

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Vieweg, Philipp P.; Kolesnikov, Yuri; Karcher, Christian;
Experimental study of a liquid metal film flow in a streamwise magnetic field. - In: Magnetohydrodynamics, Bd. 58 (2022), 1/2, S. 5-11

Continuous wetting of a surface with liquid metal is indispensable in many applications, such as in fusion reactors. In the present study, we provide data on the suppression of free-surface instabilities of liquid metal film flows under the action of strong streamwise magnetic fields in analogy to the poloidal fields used in application. We have designed and built up an experimental test setup which allows studying the influence of magnetohydrodynamics on the dynamic behaviour of liquid metal GaInSn film flows in laminar, transient, and turbulent regimes. While the width and the length of the film are adjusted at w = 23 mm and l = 120 mm, respectively, we are able to apply strong uniform magnetic fields up to B = 5 T over the entire fluid-flow volume. Moreover, the setup allows to vary the Reynolds number within the range 200 ≤ Re ≤ 1700. The corresponding Hartmann and Stuart numbers are Ha ≤ 180 and N ≤ 40, respectively. This study shows that a streamwise magnetic field is capable of suppressing free-surface instabilities even in the turbulent regime of the film flow by dampening any motion perpendicular to the applied magnetic field. Plans for future studies include the quantitative investigation of the parameter space.

Otto, Christian; Geinitz, Veronika; Kletzin, Ulf; Schimpf, Christian;
FE simulation of multi-stage wire drawing processes. - In: Alles auf Draht!, (2022), S. 55-60

Häcker, Annika-Verena; Mohr-Weidenfeller, Laura; Stolzenberg, Clara F. L.; Reinhardt, Carsten; Manske, Eberhard;
Modifications to a high-precision direct laser writing setup to improve its laser microfabrication. - In: SPIE digital library, Bd. 11989 (2022), S. 119890U-1-119890U-7

Two-photon-absorption (2PA) techniques enables the possibility to create extremely fine structures in photosensitive materials. For direct laser writing as micro- or nanofabrication a laser system can be combined with highly precise positioning systems. These are mostly limited by a few hundreds micrometer positioning range with applications based on piezoelectric stages or even just relatively few tens micrometer positioning range with applications based on galvanometer scanners. Although these techniques are precise, but stitching methods are required for larger fabrication areas. Therefore, a setup consisting of a femtosecond laser for 2PA and a nanopositioning and nanomeasuring machine (NMM-1) was developed for high precision laser writing on lager surfaces. Further developments of the system should enable a significant improvement in high-precision and stitching free direct laser writing. In order to combine the the femtosecond laser and the NMM-1 into a functional unit, to write complex structures with highest accuracy and homogeneity, further improvements like a beam expansion for a better use of the numerical aperture of the objective and a new femtosecond laser with a integrated power measurement are realized. This showed improvements in line width for nano strucuring. Advantages and disadvantages as well as further developments of the NMM-1 system will be discussed related to current developments in the laser beam and nanopositioning system optimization.

Thiele, Sebastian; Eliseyev, Ilya A.; Smirnov, Alexander N.; Jacobs, Heiko O.; Davydov, Valery Y.; Schwierz, Frank; Pezoldt, Jörg;
Electric bias-induced edge degradation of few-layer MoS2 devices. - In: Materials today, ISSN 2214-7853, Bd. 53 (2022), 2, S. 281-284

In this work, we experimentally investigate the effects of electric bias on the degradation of few-layer MoS2 back-gated field-effect transistors in ambient air. The devices were fabricated using mechanically exfoliated MoS2 flakes, which were transferred to a Si/SiO2 substrate by a PDMS-based transfer. We report an accelerated electric bias-induced degradation of the devices under investigation and used optical and scanning electron microscopy (SEM) to monitor changes of the morphology of the MoS2 channel. In particular, we found a linear dependency of the degradation on the electric field between the Ti/Au source and drain contacts. In addition, we identify four regions in which morphological changes occur, of which the edges of the MoS2 channel are most affected.

Mathew, Sobin; Lebedev, Sergey P.; Lebedev, Alexander A.; Hähnlein, Bernd; Stauffenberg, Jaqueline; Udas, Kashyap; Jacobs, Heiko O.; Manske, Eberhard; Pezoldt, Jörg;
Nanoscale surface morphology modulation of graphene - i-SiC heterostructures. - In: Materials today, ISSN 2214-7853, Bd. 53 (2022), 2, S. 289-292

A multitude gratings design consists of gratings with different pitches ranging from the micrometre down to sub 40 nm scale combined with sub 10 nm step heights modulating the surface morphology for length scale measurements is proposed. The surface morphology modulation was performed using electron beam lithography incorporating a standard semiconductor processing technology. The critical dimension, edge roughness, step heights and line morphology in dependence on the grating pitch is studied.

Nozdrenko, Dmytro; Matvienko, Tatiana; Vygovska, Oksana; Soroca, Vasil; Bogutska, Kateryna; Zholos, Alexander; Scharff, Peter; Ritter, Uwe; Prylutskyy, Yuriy;
Post-traumatic recovery of muscle soleus in rats is improved via synergistic effect of C60 fullerene and TRPM8 agonist menthol. - In: Applied nanoscience, ISSN 2190-5517, Bd. 12 (2022), 3, S. 467-478

Functional biomechanical parameters of muscle soleus contraction in rats as well as selected blood biochemical parameters were studied during the first 3 days of post-traumatic syndrome progression caused by the destruction of muscle cells by compression. Single administration of the antioxidant C60 fullerene and the selective agonist of TRPM8 channels menthol were used as therapeutic agents. Injection of C60 fullerene at a concentration of 1 mg/kg into the damaged muscle improved its contractile function by 25-28%. The use of combined injections of C60 fullerene and menthol (at the concentration 1 mg/kg) improved this index by additional 27-39% and simultaneously stabilized the decrease in muscle strength observed throughout the experiment. A tendency towards a decrease in the indexes of the above described biochemical parameters by 10-15% were found with the therapeutic administration of C60 fullerene. With combined injections of C60 fullerene and menthol, the above described biochemical parameters decreased by an additional 17-24%. The synergism between the action of menthol and C60 fullerene on the post-traumatic recovery of skeletal muscle function opens up new perspectives for the clinical application of this combination therapy.

Streck, Marco; Husung, Stephan; Hassler, Julien;
Determination and systematization of load situations for eBike drive units as basis for their design and optimization. - In: Achte IFToMM D-A-CH Konferenz 2022, (2022), S. 1-6

Torres Melgarejo, Mario André; Henning, Stefan; Zentner, Lena; Theska, René;
On the influence of geometrical deviations of flexure hinges on the trajectory behaviour of straight-line compliant mechanisms for ultra-precision applications :
Zum Einfluss von geometrischen Abweichungen von Festkörpergelenken auf das Bahnverhalten von nachgiebigen Geradführungsmechanismen für Ultrapräzisionsanwendungen. - In: Achte IFToMM D-A-CH Konferenz 2022, (2022), insges. 2 S.

Ou, Chen; Zhu, Hongqiu; Shardt, Yuri A. W.; Ye, Lingjian; Yuan, Xiaofeng; Wang, Yalin; Yang, Chunhua;
Quality-driven regularization for deep learning networks and its application to industrial soft sensors. - In: IEEE transactions on neural networks and learning systems, ISSN 2162-237X, (2022), S. 1-11
Early access

The growth of data collection in industrial processes has led to a renewed emphasis on the development of data-driven soft sensors. A key step in building an accurate, reliable soft sensor is feature representation. Deep networks have shown great ability to learn hierarchical data features using unsupervised pretraining and supervised fine-tuning. For typical deep networks like stacked auto-encoder (SAE), the pretraining stage is unsupervised, in which some important information related to quality variables may be discarded. In this article, a new quality-driven regularization (QR) is proposed for deep networks to learn quality-related features from industrial process data. Specifically, a QR-based SAE (QR-SAE) is developed, which changes the loss function to control the weights of the different input variables. By choosing an appropriate inductive bias for the weight matrix, the model provides quality-relevant information for predictive modeling. Finally, the proposed QR-SAE is used to predict the quality of a real industrial hydrocracking process. Comparative experiments show that QR-SAE can extract quality-related features and achieve accurate prediction performance.

Reimche, Maxim; Geißhirt, M.; Berghof, Steffen; Bergmann, Jean Pierre;
Innovative methodology to determine process costs for manufacturing within production networks. - In: Production at the leading edge of technology, (2022), S. 656-665

Companies that manufacture their own products and also provide after-market service are common and usually involve in-house manufacturing and assembly. The limited capacity of in-house resources and the requirement to meet delivery deadlines forces companies to deviate from the cost-optimal production strategy and to produce quantities according to demand instead of optimal lot sizes. A selective increase in the capacity of heavily utilized resources, e.g. by additional capacity of platforms or participation in peer-to-peer networks, enables companies to make savings on setup costs by producing selected articles in optimal load sizes. Such savings can be used to price third-party capacity. This paper presents a new method for pricing the procurement of capacity in a peer-to-peer network and demonstrates it on an industrial example.