Erscheinungsjahr 2024

Anzahl der Treffer: 73
Erstellt: Wed, 17 Jul 2024 23:13:54 +0200 in 0.3257 sec


Baumstark, Alexander; Paradies, Marcus; Sattler, Kai-Uwe; Kläbe, Steffen; Baumann, Stephan
So far and yet so near - accelerating distributed joins with CXL. - In: 20th International Workshop on Data Management on New Hardware (DaMoN 2024), (2024), 7, insges. 9 S.

Distributed partitioned joins are one of the most expensive operators in distributed DBMSs where a major part of the execution is attributed to network transfer costs. Although high-speed network technologies, such as RDMA, can lower this cost, they still come with significantly higher latency than local DRAM access. The emerging CXL interconnect protocol promises to provide direct and cache-coherent access to remote memory while offering byte-addressable memory access without CPU intervention. For short-distance communication in distributed DBMSs, CXL represents an interesting alternative for low-latency requirements. In this work, we explore how CXL can be leveraged for engine-internal communication and data exchange. We discuss and apply communication strategies to distributed joins. We emulate various CXL characteristics based on optimistic and pessimistic assumptions on the real performance of upcoming CXL devices and evaluate their impact on the execution of distributed joins. Our results show that CXL has the potential to improve distributed join performance.



https://doi.org/10.1145/3662010.3663449
Tangalychev, Roman; Korotenko, Vasilii; Efimov, Igor; Efimov, Oleg N.
Properties of AlCl3 guanidine deep eutectic solvent with addition of polyethylene oxide of different molecular weights supported by quantum-chemical calculation. - In: Journal of energy storage, ISSN 2352-152X, Bd. 96 (2024), 112665, S. 1-8

Deep eutectic solvent of AlCl3 with guanidine HCl was synthesized in the molar ratio 3:1 in the presence of polyethylene glycols of various molecular weights from 1500 to 5&hahog;106 g/mol. Concentration of polymer was 2.5 %, 5 % and 10 %. Temperature dependence between 25 and 70 ˚C of conductivity of each electrolyte was calculated from the cyclic voltammetry of aluminum deposition-stripping measurements. It was found that conductivity increases with molecular weight of polymer in the interval between 2 and 10 kD. This result was interpreted as binding of AlCl3 guanidine to two different sites which have hydroxyl (chain ends) and ether (middle chain) oxygen with relatively higher and lower binding energy respectively. Polymer with longer chain has more low energy binding sites which causes lesser binding and consequently higher conductivity of electrolyte. B3LYP-D3 and DLPNO-CCSD(T) computations support experimental results. DES are discussed in terms of Pearson HSAB principle.



https://doi.org/10.1016/j.est.2024.112665
Motuziuk, Olexandr; Nozdrenko, Dmytro; Prylutska, Svitlana; Vareniuk, Igor; Cherepanov, Vsevolod; Bogutska, Kateryna; Rudenko, Sergii; Prylutskyy, Yuriy; Piosik, Jacek; Ritter, Uwe
C60 fullerene reduces the level of liver damage in chronic alcohol intoxication of rats. - In: Molecules, ISSN 1420-3049, Bd. 29 (2024), 13, 2951, S. 1-15

The liver is the main organ responsible for the metabolism of ethanol, which suffers significantly as a result of tissue damage due to oxidative stress. It is known that C60 fullerenes are able to efficiently capture and inactivate reactive oxygen species in in vivo and in vitro systems. Therefore, the purpose of this study is to determine whether water-soluble C60 fullerene reduces the level of pathological process development in the liver of rats induced by chronic alcohol intoxication for 3, 6, and 9 months, depending on the daily dose (oral administration; 0.5, 1, and 2 mg/kg) of C60 fullerene throughout the experiment. In this context, the morphology of the C60 fullerene nanoparticles in aqueous solution was studied using atomic force microscopy. Such biochemical parameters of experimental animal blood as ALT (alanine aminotransferase), AST (aspartate aminotransferase), GGT (gamma-glutamyl transferase) and ALP (alkaline phosphatase) enzyme activities, CDT (carbohydrate-deficient transferrin) level, values of pro-antioxidant balance indicators (concentrations of H2O2 (hydrogen peroxide) and GSH (reduced glutathione), activities of CAT (catalase), SOD (superoxide dismutase) and GPx (selenium-dependent glutathione peroxidase)), and pathohistological and morphometric features of liver damage were analyzed. The most significant positive change in the studied biochemical parameters (up to 29 ± 2% relative to the control), as markers of liver damage, was recorded at the combined administration of alcohol (40% ethanol in drinking water) and water-soluble C60 fullerenes in the optimal dose of 1 mg/kg, which was confirmed by small histopathological changes in the liver of rats. The obtained results prove the prospective use of C60 fullerenes as powerful antioxidants for the mitigation of pathological conditions of the liver arising under prolonged alcohol intoxication.



https://doi.org/10.3390/molecules29132951
Heyder, Florian; Mellado, Juan Pedro; Schumacher, Jörg
Generative convective parametrization of a dry atmospheric boundary layer. - In: Journal of advances in modeling earth systems, ISSN 1942-2466, Bd. 16 (2024), 6, e2023MS004012, S. 1-20

Turbulence parametrizations will remain a necessary building block in kilometer-scale Earth system models. In convective boundary layers, where the mean vertical gradients of conserved properties such as potential temperature and moisture are approximately zero, the standard ansatz which relates turbulent fluxes to mean vertical gradients via an eddy diffusivity has to be extended by mass-flux parametrizations for the typically asymmetric up- and downdrafts in the atmospheric boundary layer. We present a parametrization for a dry and transiently growing convective boundary layer based on a generative adversarial network. The training and test data are obtained from three-dimensional high-resolution direct numerical simulations. The model incorporates the physics of self-similar layer growth following from the classical mixed layer theory of Deardorff by a renormalization. This enhances the training data base of the generative machine learning algorithm and thus significantly improves the predicted statistics of the synthetically generated turbulence fields at different heights inside the boundary layer, above the surface layer. Differently to stochastic parametrizations, our model is able to predict the highly non-Gaussian and transient statistics of buoyancy fluctuations, vertical velocity, and buoyancy flux at different heights thus also capturing the fastest thermals penetrating into the stabilized top region. The results of our generative algorithm agree with standard two-equation mass-flux schemes. The present parametrization provides additionally the granule-type horizontal organization of the turbulent convection which cannot be obtained in any of the other model closures. Our proof of concept-study also paves the way to efficient data-driven convective parametrizations in other natural flows.



https://doi.org/10.1029/2023MS004012
Ilchmann, Achim; Kirchhoff, Jonas; Schaller, Manuel
Port-Hamiltonian descriptor systems are relative generically controllable and stabilizable. - In: Mathematics of control, signals, and systems, ISSN 1435-568X, Bd. 0 (2024), 0, insges. 37 S.

The present work is a successor of Ilchmann and Kirchhoff (Math Control Signals Syst 33:359-377, 2021) on generic controllability and of Ilchmann and Kirchhoff (Math Control Signals Syst 35:45-76, 2022) on relative generic controllability of linear differential-algebraic equations. We extend the result from general, unstructured differential-algebraic equations to differential-algebraic equations of port-Hamiltonian type. We derive results on relative genericity. These findings are the basis for characterizing relative generic controllability of port-Hamiltonian systems in terms of dimensions. A similar result is proved for relative generic stabilizability.



https://doi.org/10.1007/s00498-024-00392-7
Calmbach, Benjamin; Moreno Pérez, Jaime Alberto; Reger, Johann
Minimizing the homogeneous L2-gain of homogeneous differentiators. - In: European journal of control, ISSN 1435-5671, Bd. 0 (2024), 0, 101039, S. 1-8

The differentiation of noisy signals using the family of homogeneous differentiators is considered. It includes the high-gain (linear) as well as robust exact (discontinuous) differentiator. To characterize the effect of noise and disturbance on the differentiation estimation error, the generalized, homogeneous L2-gain is utilized. Analog to the classical Lp-gain, it is not defined for the discontinuous case w.r.t. disturbances acting on the last channel. Thus, only continuous differentiators are addressed. The gain is estimated using a differential dissipation inequality, where a scaled Lyapunov function acts as storage function for the homogeneous L2 supply rate. The fixed differentiator gains are scaled with a gain-scaling parameter similar to the high-gain differentiator. This paper shows the existence of an optimal scaling which minimizes the homogeneous L2-gain estimate and provides a procedure to obtain it locally. Differentiators of dimension two are considered and the results are illustrated via numerical evaluation and a simulation example.



https://doi.org/10.1016/j.ejcon.2024.101039
Köpsell, Saskia; Oertel, Simon
Digitalization attempts in higher education: the role of imprinting and the effect of business departments. - In: Studies in higher education, ISSN 1470-174X, Bd. 0 (2024), 0, S. 1-19

In recent decades, higher education institutions (HEIs) have increasingly been exposed to a market logic that has led them to adopt structures and practices that are common in for-profit firms. In our study, we analyze how HEIs react to the increasing demands of digitalization and which factors explain the adoption of relevant structures. Based on 379 HEIs in Germany, our findings show that imprinting is of great importance for the implementation of a position for digitalization - that is, HEIs founded in a more recent phase of higher education in Germany are more likely to create a leadership position for digitalization. At the same time, we find that imprinting has no effect on the creation of more operational positions for digitalization but that the existence of a business department in HEIs has a positive effect. We discuss these findings in the context of higher education research and questions about factors influencing the adoption of practices and structures in HEIs.



https://doi.org/10.1080/03075079.2024.2355349
Reum, Thomas;
Consequences of the potential gauging process for modeling electromagnetic wave propagation. - In: IEEE open journal of antennas and propagation, ISSN 2637-6431, Bd. 0 (2024), 0, S. 1-12

This predominantly theoretical article focuses on a qualitative discussion of peculiarities, which are introduced in practical electromagnetic (EM) wave propagation scenarios when the gauge for the electrodynamic potentials is not chosen in accordance to the appropriate space-time metric of the underlying physical framework. Based on ordinary vector calculus, this is done for the viewpoint of radio frequency (RF) engineers by using two examples of guided EM waves: one large-scale case of a terrestrial scenario and one small-scale case involving a device level setup. Readers may benefit especially from this practical orientation, since gauging is often analyzed primarily mathematical by solely arguing on terms of equations instead of discussing concrete applications. The provided context aims to enhance the usual perspective and is applicable for a wide class of situations involving various wave types at any frequency.



https://doi.org/10.1109/OJAP.2024.3412162
Lauer, Kevin; Müller, Robin; Peh, Katharina; Schulze, Dirk; Krischok, Stefan; Reiß, Stephanie; Frank, Andreas; Ortlepp, Thomas
Investigation of Tl-doped silicon by low-temperature photoluminescence during light-induced degradation treatments. - In: Physica status solidi, ISSN 1862-6319, Bd. n/a (2024), n/a, 2400287, S. 1-6

Scientific progress is made in understanding photoluminescence (PL) lines in thallium-doped silicon. Two PL lines called A and P, which appear after quenching, are found to exhibit irreversible as well as reversible behavior under the application of light-induced degradation (LID) treatments. The reversible behavior is similar to changes of a P line in indium-doped silicon due to LID treatments, which have led to the identification of this P line to be caused by an InSi-Sii-defect. By exploiting the metastability of defects from the ASi-Sii category, the experimental findings of this study indicate that the underlying defect for the A and P line in thallium-doped silicon is the TlSi-Sii-defect.



https://doi.org/10.1002/pssa.202400287
Jahn, Hannes; Böhm, Valter; Zentner, Lena
Analysis of deformation in tensegrity structures with curved compressed members. - In: Meccanica, ISSN 1572-9648, Bd. 0 (2024), 0, insges. 12 S.

Tensegrity structures are prestressed structures consisting of compressed members connected by prestressed tensioned members. Due to their properties, such as flexibility and lightness, mobile robots based on these structures are an attractive subject of research and are suitable for space applications. In this work, a mobile robot based on a tensegrity structure with two curved members connected by eight tensioned strings is analyzed in terms of deformation in the curved members. Further, the difference in locomotion trajectory between the undeformed and deformed structure after the prestress is analyzed. For that, the theory of large deflections of rod-like structures is used. To determine the relationship between acting forces and the deformation, the structure is optimized using minimization algorithms in Python. The results are validated by parameter studies in FEM. The analysis shows that the distance between the two curved members significantly influences the structure’s locomotion. It can be said that the deformation of the components significantly influences the locomotion of tensegrity structures and should be considered when analyzing highly compliant structures.



https://doi.org/10.1007/s11012-024-01833-y
Sauni Camposano, Yesenia Haydee; Jaekel, Konrad; Riegler, Sascha S.; Matthes, Sebastian; Glaser, Marcus; Peter, Nicolas J.; Vardo, Emina; Bartsch, Heike; Schwaiger, Ruth; Bergmann, Jean Pierre; Gallino, Isabella; Schaaf, Peter
Controlling propagation velocity in Al/Ni reactive multilayer systems by periodic 2D surface structuring. - In: Advanced engineering materials, ISSN 1527-2648, Bd. n/a (2024), n/a, 2302272, S. 1-11

The chemical energy released as heat during the exothermic reaction of reactive multilayer systems has shown potential applications in various technological areas, e.g., in joining applications. However, controlling the heat release rate and the propagation velocity of the reaction is required to enhance their performance in most of these applications. Herein, a method to control the propagation velocity and heat release rate of the system is presented. The sputtering of Al/Ni multilayers on substrates with periodic 2D surface structures promotes the formation of growth defects into the system. This modification in the morphology locally influences the reaction characteristics. Tailoring the number of 2D structures in the substrate enables the control of the velocity and maximum temperature of the propagation front. The morphology of the produced reactive multilayers is investigated before and after reaction using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. In addition, the enthalpy of the system is obtained through calorimetric analysis. The self-sustained and self-propagating reaction of the systems is monitored by a high-speed camera and a high-speed pyrometer, thus revealing the propagation velocity and the temperatures with time resolution in the microsecond regime.



https://doi.org/10.1002/adem.202302272
Kirchhoff, Jonas;
Generic observability for port-Hamiltonian descriptor systems. - In: Mathematics of control, signals, and systems, ISSN 1435-568X, Bd. 0 (2024), 0, insges. 43 S.

The present work is a successor of Ilchmann and Kirchhoff (Math Control Signals Syst 33:359-377, 2021. https://doi.org/10.1007/s00498-021-00287-x), Ilchmann and Kirchhoff (Math Control Signals Syst 35:45-76, 2023. https://doi.org/10.1007/s00498-021-00287-x) on (relative) generic controllability of unstructured linear differential-algebraic systems and of Ilchmann et al. (Port-Hamiltonian descriptor systems are generically controllable and stabilizable. Submitted to Mathematics of Control, Signals and Systems, 2023. https://arxiv.org/abs/2302.05156) on (relative) generic controllability of port-Hamiltonian descriptor systems. We extend their results to (relative) genericity of observability. For unstructured differential-algebraic systems, criteria for (relative) generic observability are derived from Ilchmann and Kirchhoff (Math Control Signals Syst 35:45-76, 2023. https://doi.org/10.1007/s00498-021-00287-x) using duality. This is not possible for port-Hamiltonian systems. Hence, we tweak the results of Ilchmann et al. (Port-Hamiltonian descriptor systems are generically controllable and stabilizable. Submitted to Mathematics of Control, Signals and Systems, 2023. https://arxiv.org/abs/2302.05156) and derive similar criteria as for the unstructured case. Additionally, we consider certain rank constraints on the system matrices.



https://doi.org/10.1007/s00498-024-00388-3
Graske, Marcus; Sauni Camposano, Yesenia Haydee; Vardo, Emina; Matthes, Sebastian; Schaaf, Peter
Mechanical ignition of Al/Ni reactive multilayer systems: influence of impacting material, its properties, and geometric characteristics. - In: Advanced engineering materials, ISSN 1527-2648, Bd. n/a (2024), n/a, 2400479, S. 1-13

Al/Ni reactive multilayer systems (RMS) with a bilayer thickness of Λ = 50 nm and total thickness th = 5 μm on a SiO2 substrate exhibit a self-propagating reaction after ignition. A common method to initiate the self-propagating reaction is by electric spark ignition. Herein, RMS are ignited by a mechanical impact using various materials with indeterminate geometries to investigate the basic mechanisms. SiO2, glass, PMMA, and resin-bonded SiC particles are used as impacting material with different geometrical impact areas. The used materials are placed on top of the RMS and a mechanical impulse is applied. The ignition behavior of the RMS is subsequently evaluated and classified. Additionally, the impacted RMS are examined by microscopy to reveal the damage pattern. By correlating particle size ⟨Dparticle⟩ and spacing ⟨dhole⟩ of the penetrating materials, an ignition threshold can be established. Moreover, the results demonstrate that the energy input threshold can be reduced through a strategic distribution of particles within the impacting and penetrating geometry. This provides valuable insights into the mechanical ignition fundamental and supports future applications of mechanical ignition of RMS.



https://doi.org/10.1002/adem.202400479
Stauffenberg, Jaqueline; Belkner, Johannes; Dontsov, Denis; Herzog, Ludwig; Hesse, Steffen; Rangelow, Ivo W.; Ortlepp, Ingo; Kissinger, Thomas; Manske, Eberhard
Investigations on tip-based large area nanofabrication and nanometrology using a planar nanopositioning machine (NFM-100). - In: Measurement science and technology, ISSN 1361-6501, Bd. 35 (2024), 8, 085011, S. 1-14

This paper explores large area application of tip-based nanofabrication by field emission scanning probe lithography and showcases the simultaneous possibility of atomic force microscopy on macroscopic scales. This is made possible by the combination of tip-based technology and a planar nanopositioning and nanomeasuring machine. Using long range atomic force microscopy measurement of regular grating structures, the performance of the machine is thoroughly characterized over the full 100 mm range of motion of the positioning machine, which was confirmed by repeated measurements. After initially focussing on achieving the minimum line width of 40 nm in microscopic areas, a grating with a pitch of 1 μm is additionally fabricated over a total length of 10 mm, whereby the dimensions and deviations are also considered.



https://doi.org/10.1088/1361-6501/ad4668
Moreira, Pedro H. O.; Soydan, Alper K.; Reiprich, Johannes; Isaac, Nishchay Angel; Aliabadian, Bardia; Vernizzi, Guilherme J.; Jacobs, Heiko O.
Patterned liquid micro rails for the transport of micrometer sized chips. - In: Advanced Materials Technologies, ISSN 2365-709X, Bd. n/a (2024), n/a, 2400235, S. 1-11

Transport and alignment of microscopic chips are important steps in microelectronics component integration with common approaches being pick-and-place, microfluidics, parallel transfer and self-assembly. An alternate transport approach of microscopic chips is proposed using patterned liquid micro rails as chaperones. The surface free energy and interfacial free energy minimization of all constituents enable the creation of stable pathways. This allows for chip-attachment to rails, while the liquid layer lubricates chip-sliding. Monorails, digital monorails, and digital birails are investigated for chip movement behavior. Chip position and speed can be controlled using liquid flow in closed chambers. Speeds from 10 to 400 mm s−1 are achieved with translation distances as long as 50 mm. It is discovered that chips can selectively cross rail discontinuities of up to 500 µm, allowing for chip position control through a stop-and-go motion. A programmable liquid rails-based chip conveyor system is demonstrated by transporting diodes to receptor sites where they undergo self-assembly.



https://doi.org/10.1002/admt.202400235
Wang, Honglei; Cheng, Pengfei; Wu, Bing; Yan, Yong; Schaaf, Peter; Sofer, Zdeněk; Wang, Dong
2D metal phosphorous trichalcogenides (MPCh3) for sustainable energy storage and conversion: nanoarchitectonics and advanced applications. - In: Advanced functional materials, ISSN 1616-3028, Bd. n/a (2024), n/a, 2407432, S. 1-22

2D metal phosphorous trichalcogenides (MPCh3) have attracted considerable attention in sustainable energy storage and conversion due to their distinct physical and chemical characteristics, such as adjustable energy bandgap, significant specific surface area, and abundant active sites. However, research on 2D MPCh3 primarily focuses on electrocatalysis, and understanding its energy conversion and storage mechanisms remains incomplete. This review comprehensively summarizes recent advancements in energy storage and conversion using 2D MPCh3-based materials of various structures. It begins with a discussion of the distinctive properties and preparation techniques of 2D MPCh3, followed by a focus on the rational design and development of these materials for diverse energy-related applications, including rechargeable batteries, supercapacitors, electrocatalysis, photocatalysis, and desalination. Finally, it outlines the key challenges and prospects for future research on 2D MPCh3 materials.



https://doi.org/10.1002/adfm.202407432
Vardo, Emina; Sauni Camposano, Yesenia Haydee; Matthes, Sebastian; Glaser, Marcus; Bartsch, Heike; Hildebrand, Jörg; Bergmann, Jean Pierre; Schaaf, Peter
Impact of substrate thickness and surface roughness on Al/Ni multilayer reaction kinetics. - In: Advanced engineering materials, ISSN 1527-2648, Bd. n/a (2024), n/a, 2302269, S. 1-10

Reactive multilayers comprising alternating nanoscale layers of Al and Ni exhibit potential across various applications, including localized heating for welding and joining. Control over reaction properties is pivotal for emerging applications, such as chemical time delays or neutralization of biological or chemical weapons. In this research, insights are offered into the intricate interplay between substrate thickness, surface roughness, and the behavior of Al/Ni reactive multilayers, opening avenues for tailored applications in various domains. To observe this interplay, silica with various thicknesses from 0.4 to 1.6 μm is deposited on polished single-crystalline Si and rough poly-Si base substrates. Additionally, to analyze the impact of varying silica thickness along the sample length on reaction behavior, silica in steplike shape is fabricated. Subsequently, Al/Ni multilayers with 5 μm total thickness and 20 or 50 nm bilayer periodicities are deposited. Reaction velocity and temperature are monitored with a high-speed camera and pyrometer. In the results, it is indicated that silica thickness significantly affects self-propagation in multilayers. The reaction is not self-sustained for silica layers ≤ 0.4 μm, depending on bilayer periodicity and substrate roughness. The velocity increases or decreases based on the direction of reaction propagation, whether it moves upward or downward, in relation to the thickness of silica.



https://doi.org/10.1002/adem.202302269
Bartsch, Heike; Kaltwasser, Mahsa; Karimi, Kiana; Müller, Jens
Low insertion loss interposer approach for RF applications based on commercial LTCC tape, alkaline-free glass and printed metallization. - In: Materials research bulletin, ISSN 0025-5408, Bd. 178 (2024), 112902, S. 1-5

Materials with high RF performance are in increasing demand due to the needs of modern telecommunications. Glass and low-temperature co-fired ceramics (LTCCs) are both interesting candidates for the design of complex signal transmission systems. Glass can be processed in large panels, and has suitable structure dimensions for silicon processing, but its multilayer capability is limited. LTCC is a mature technology for complex multilayer assemblies, but the structure dimensions and conductor line resolution are restricted by the need to use screen printing technology. The approach presented here combines the advantages of both technological domains: a thin glass sheet is bonded with no additional material to a LTCC multilayer ceramic and sintered to form a tight joint. Metallization of the glass is created using printable pastes and electroplating. Two fabrication routes are compared: etching of printed thick film metal layers, and semi-additive structuring. The results of RF measurements show a low attenuation per unit length for both types of metallization, indicating that our approach is a promising one for the integration of heterogeneous systems of RF transmission modules.



https://doi.org/10.1016/j.materresbull.2024.112902
Hanson, Kenneth R.; Döring, Nicola; Walter, Roberto
Sex doll specifications versus human body characteristics. - In: Archives of sexual behavior, ISSN 1573-2800, Bd. 53 (2024), 6, S. 2025-2033

Sex dolls have been criticized for reproducing unrealistic expectations about human bodies. Yet precise sex doll measurements are lacking in the literature nor has there been any systematic attempt to determine the extent to which sex dolls exaggerate human characteristics. To address this gap, we compared the specifications of sex dolls marketed in the USA with the characteristics of women and men living in the USA. Specifically, we tested if and to what degree female dolls were slimmer (H1) and male dolls more muscular (H2) than female and male humans, respectively. Furthermore, we tested if and to what degree female dolls’ breasts (H3) and male dolls’ penises (H4) were larger than those of women and men. We also tested if sex dolls’ observed race/ethnicity was more often White than that of the US population (H5). In 2023, we collected the measures of all 757 full-body sex dolls marketed by the US retailer SexyRealSexDolls.com. Body measures from the US population were extracted from scientific literature. Descriptive and inferential statistical analyses were performed using R. All hypotheses were fully or partially confirmed, which indicated that sex dolls marketed in the USA are not realistic depictions of the US population but hypergendered (H1, H2), hypersexualized (H3, H4), and racially fetishized (H5). Implications of the lack of realism are discussed.



https://doi.org/10.1007/s10508-024-02871-z
Alkorta, Manex; Cizek, Rebecca; Néel, Nicolas; Frederiksen, Thomas; Kröger, Jörg
Impact of single-melamine tautomerization on the excitation of molecular vibrations in inelastic electron tunneling spectroscopy. - In: Nano letters, ISSN 1530-6992, Bd. 24 (2024), 24, S. 7195-7201

Vibrational quanta of melamine and its tautomer are analyzed at the single-molecule level on Cu(100) with inelastic electron tunneling spectroscopy. The on-surface tautomerization gives rise to markedly different low-energy vibrational spectra of the isomers, as evidenced by a shift in mode energies and a variation in inelastic cross sections. Spatially resolved spectroscopy reveals the maximum signal strength on an orbital nodal plane, excluding resonant inelastic tunneling as the mechanism underlying the quantum excitations. Decreasing the probe-molecule separation down to the formation of a chemical bond between the melamine amino group and the Cu apex atom of the tip leads to a quenched vibrational spectrum with different excitation energies. Density functional and electron transport calculations reproduce the experimental findings and show that the shift in the quantum energies applies to internal molecular bending modes. The simulations moreover suggest that the bond formation represents an efficient manner of tautomerizing the molecule.



https://doi.org/10.1021/acs.nanolett.4c00904
Gizatullin, Bulat; Mattea, Carlos; Stapf, Siegfried; Wissel, Till; Buntkowsky, Gerd
NMR relaxation dispersion of liquids adsorbed on modified surfaces of SBA-15 mesoporous silica. - In: The journal of physical chemistry, ISSN 1932-7455, Bd. 128 (2024), 21, S. 8785-8796

The NMR relaxation dispersion of 1H and 2H nuclei in water and alkanes was studied in mesoporous SBA-15 silica in its native state and with modified internal surfaces. By comparison with silica gel of comparable characteristic pore size, a qualitative agreement of the relaxation dispersion was found. In the absence of detectable amounts of paramagnetic centers, intramolecular relaxation is approximated by the model of Reorientations Mediated by Translational Displacements (RMTD), which assumes rigid molecules diffusing along curved surfaces and experiencing long-term memory of their relative orientation due to their polarity. For all liquids, significant relaxation dispersion is found so that the vanishing polarity of alkanes does not allow the assumption of a negligible surface interaction. The difference in dispersion shape between 1H and 2H nuclei, relaxing by dipolar and quadrupolar mechanisms, respectively, allows the reconstruction of the intermolecular contribution to relaxation, which has not yet been studied systematically in porous media. A model based on the relative contributions of intra- and intermolecular interactions as well as hydrogen exchange with OH- and NH2-groups is presented.



https://doi.org/10.1021/acs.jpcc.4c00645
Baumer, Christoph; Schmidt, Udo; Bund, Andreas
Investigating the suitability of various silver(I) complexes for use in a cyanide-free silver electrolyte. - In: Coatings, ISSN 2079-6412, Bd. 14 (2024), 5, 618, S. 1-16

The suitability of various nitrogen, sulfur, oxygen, and phosphorus compounds as complexing agents in a silver electrolyte was examined by using potentiometric titration under practical conditions. The setup consisted of three electrodes to measure the pH and the activity of the silver ions simultaneously. Different ratios of silver to complexing agent from 1:10 to 1:1 at a constant ionic strength of 0.2 mol/L were investigated. The type of the complexes and their corresponding critical stability constants were evaluated by fitting the measured data using a self-developed algorithm. The pH and Nernst potential curve were calculated for the assumed complexes based on the law of mass action to find the best approximation. The correct definition of the occurring species is challenging and can lead to significant changes in the calculation of stability constants. For this reason, the measured silver potential curves were primarily used for the rating of the complexing agents. An evaluation of the measurements shows that the donor atom of the complexing agent and its ligand field strongly affected the stability and type of the complexes. Only a few complexing agents were found to be suitable for use in the cyanide-free silver electrolyte.



https://doi.org/10.3390/coatings14050618
Ilgaz, Fatih; Spetzler, Elizaveta; Wiegand, Patrick; Faupel, Franz; Rieger, Robert; McCord, Jeffrey; Spetzler, Benjamin
Miniaturized double-wing ∆E-effect magnetic field sensors. - In: Scientific reports, ISSN 2045-2322, Bd. 14 (2024), 11075, S. 1-12

Magnetoelastic micro-electromechanical systems (MEMS) are integral elements of sensors, actuators, and other devices utilizing magnetostriction for their functionality. Their sensitivity typically scales with the saturation magnetostriction and inversely with magnetic anisotropy. However, large saturation magnetostriction and small magnetic anisotropy make the magnetoelastic layer highly susceptible to minuscule anisotropic stress. It is inevitably introduced during the release of the mechanical structure during fabrication and severely impairs the device’s reproducibility, performance, and yield. To avoid the transfer of residual stress to the magnetic layer, we use a shadow mask deposition technology. It is combined with a free-free magnetoelectric microresonator design to minimize the influence of magnetic inhomogeneity on device performance. Magnetoelectric resonators are experimentally and theoretically analyzed regarding local stress anisotropy, magnetic anisotropy, and the ΔE-effect sensitivity in several resonance modes. The results demonstrate an exceptionally small device-to-device variation of the resonance frequency < 0.2% with large sensitivities comparable with macroscopic ΔE-effect magnetic field sensors. This development marks a promising step towards highly reproducible magnetoelastic devices and the feasibility of large-scale, integrated arrays.



https://doi.org/10.1038/s41598-024-59015-5
Conde, Melisa; Mikhailova, Veronika; Döring, Nicola
“I have the feeling that the person is here”: older adults’ attitudes, usage intentions, and requirements for a telepresence robot. - In: International Journal of Social Robotics, ISSN 1875-4805, Bd. 0 (2024), 0, insges. 21 S.

The social integration of older adults has been shown to be vital for successful aging. Innovative communication technologies, such as telepresence robots, can protect older adults against loneliness and social isolation by helping them stay connected to their social networks. This human-centered qualitative study aims to identify the attitudes (research question 1, RQ1), intentions to use (RQ2), and requirements (RQ3) of older adults for robot-mediated communication (RMC) via a telepresence robot. Semi-structured individual interviews were conducted with N = 30 older adults from Germany, who evaluated storyboard illustrations depicting a fictional RMC scenario between a grandparent and their adult grandchild. The study identified 3 attitude groups towards telepresence robots among participants: positive, negative, and conflicting attitudes (RQ1). Furthermore, based on their intentions of use, participants were classified into reluctant future users (n = 12), future non-users (n = 10), and enthusiastic future users (n = 8) (RQ2). Finally, the study identified technological, social, and age-related requirements of older adults for a telepresence robot (RQ3). Practical recommendations are provided based on these findings, such as leveraging older adults’ current technology-related skills, adapting technologies to older adults’ lifestyles and social networks, and designing technologies that contribute to older adults aging in place. This study contributes to the human-centered design of telepresence robots that support the social integration of older adults.



https://doi.org/10.1007/s12369-024-01143-z
Bohm, Sebastian; Phi, Hai Binh; Dittrich, Lars; Runge, Erich
Chip-integrated non-mechanical microfluidic pump driven by electrowetting on dielectrics. - In: Lab on a chip, ISSN 1473-0189, Bd. 24 (2024), 11, S. 2893-2905

A microfluidic pump is presented that generates its pumping action via the EWOD (electrowetting-on-dielectric) effect. The flow is generated by the periodic movement of liquid-vapor interfaces in a large number (≈10^6) of microcavities resulting in a volume change of approx. 0.5 pl per cavity per pump stroke. The total flow resulting from all microcavities adds up to a few hundred nanolitres per cycle. Passive, topologically optimized, non-mechanical Tesla valves are used to rectify the flow. As a result, the micropump operates without any moving components. The dimensioning, fabrication, and characterization process of the micropump are described. Device fabrication is done using conventional manufacturing processes from microsystems technology, enabling cost-effective mass production on wafer-level without additional assembly steps like piezo chip-level bonding, etc. This allows for direct integration into wafer-based microfluidic or lab-on-a-chip applications. Furthermore, first measurement results obtained with prototypes of the micropump are presented. The voltage- and frequency-dependent pump performance is determined. The measurements show that a continuous flow rate larger than 0.2 ml min^−1 can be achieved at a maximum pump pressure larger than 12 mbar.



https://doi.org/10.1039/D4LC00178H
Noßmann, Bastian; Yu, Zuodong; Das, Ankur; Schulte, Stefan; Néel, Nicolas; Wu, Chien-Te; Kirchner, Stefan; Kröger, Jörg
Yu-Shiba-Rusinov states induced by single Fe atoms on reconstructed compound superconductor V3Si. - In: Surface science, ISSN 1879-2758, Bd. 746 (2024), 122504, S. 1-10

Reconstructed surfaces of the A15-compound superconductor V3Si(100) that are possibly induced by the segregation of bulk impurities serve as platforms to study the dependence of Yu-Shiba-Rusinov states induced by a single Fe atom on the adsorption site. Their number, energy and electron-hole asymmetry vary strongly with the atomic environment of the Fe atom. These variations are indicative of different Fe d-orbitals being active in the site-dependent exchange coupling with the substrate Cooper pairs. Spatially resolved spectroscopy gives rise to a short decay length of the Yu-Shiba-Rusinov states and thereby suggests the three-dimensional character of the scattering process underlying the bound states.



https://doi.org/10.1016/j.susc.2024.122504
Rashidifar, Ali; Römer, Florian; Semper, Sebastian; Gutzeit, Nam; Del Galdo, Giovanni
Broadband DRA with uniform angular dependent delay for indoor localization. - In: IEEE access, ISSN 2169-3536, Bd. 12 (2024), S. 63644-63654

Estimating the Time Difference of Arrival (TDoA), is a simple yet reliable technique to accurately perform an indoor monostatic localization. To implement TDoA estimation, one approach is to utilize a broadband radar system equipped with multiple receiving antenna elements. To obtain the Time of Arrival (ToA) at each antenna element, the round-trip time is required. However, the round-trip time does not only consist of the propagation delay in free space but the propagation delay within the antenna as well. To perform the localization precisely, it is desired that an antenna element introduces a uniform delay in all directions. To this end, a compact rectangular dielectric resonator antenna is designed for the operating frequency of 6.5 GHz with a fractional bandwidth of 20%. Al2O3 with a dielectric constant of 9.8 is used for the substrate as well as the dielectric resonator. The antenna is designed to provide a high correlation between the input and the output pulses. To investigate the correlation, the antenna is excited with a modulated Gaussian pulse and the radiated pulses are studied. The antenna possesses an excellent behavior in terms of pulse preservation for the upper hemisphere. Therefore, when incoming pulses from the same distance but different directions impinge on the antenna, they reach the port of the antenna at a similar time. It is shown that this feature of the proposed antenna allows the utilization of TDoA estimation without the need for a calibration step. The characteristics of the antenna are verified by simulation and measurement.



https://doi.org/10.1109/ACCESS.2024.3395124
Döring, Nicola; Walter, Roberto
An experiment on the press coverage of child sexual abuse: can readers differentiate between good and bad reporting?. - In: Mass communication & society, ISSN 1532-7825, Bd. 0 (2024), 0, S. 1-23

News reporting on child sexual abuse (CSA) plays an important role in educating the public and fighting sexual violence, according to the public interest model of normative media theory. Bad reporting, however, is widespread and hinders a solution-oriented approach. Against this backdrop, the current study investigated which normative and subjective criteria are used by readers when they assess the quality of CSA newspaper reporting (RQ1). Furthermore, it was tested if readers can differentiate between good and bad CSA reporting quality (RQ2) and if their personal involvement in the topic - concerning victimization, exposure to CSA reporting, CSA knowledge - influences assessments of journalistic quality (RQ3). An experimental online study with a national quota sample of N = 2724 adults (18–65 years; Mage  = 44.1; 52.5% women) from Germany was conducted in 2020. The study is preregistered and further materials are shared on osf.io. It turned out that readers mostly used the normative criteria to assess CSA reporting quality that are suggested by the academic literature (RQ1). Readers were able to differentiate between CSA reporting with high versus low journalistic quality (RQ2) - irrespective of their own CSA victimization (RQ3). Readers rated bad reporting as mediocre, though, indicating potential unawareness of certain quality issues.



https://doi.org/10.1080/15205436.2024.2335344
Döring, Nicola; Mohseni, Rohangis; Pietras, Laura; Dekker, Arne; Briken, Peer
Research in brief: how prevalent is rough sex? Results from a national online sample of adults in Germany. - In: Perspectives on sexual and reproductive health, ISSN 1931-2393, Bd. 56 (2024), 2, S. 90-97

Background: Rough sex refers to consensual sexual activities that incorporate playful aggression, such as hair pulling, spanking, or choking. It is relevant in the context of sexual health as it can enhance sexual arousal, pleasure, and intimacy among consenting partners. However, it can also be associated with consent violations, discomfort, and injuries ranging from mild to severe or even fatal. The prevalence of rough sex in Germany is widely unknown. Our study aims to establish, for the first time, the overall age-related and gender-related prevalence rates of active and passive rough sex involvement among adults in Germany. Methods: A national online sample of 1101 adults from Germany, aged 18-69 years (50% men, 49% women, 1% gender-diverse individuals) gave informed consent and reported on their lifetime engagement in rough sex in active and passive roles. We recruited participants through a professional panel provider for a multi-themed sexual health survey. Data analysis was conducted using R, with 95% confidence intervals of prevalence rates computed to answer the research questions. Results: Lifetime prevalence of rough sex involvement was 29%. Adults below the age of 40 reported higher rates of involvement (up to 43%) than people over 40 (up to 26%). Men reported predominantly active role involvement and women reported primarily passive role involvement. Discussion: Results show that rough sex is common. Sexual health professionals, educators, and researchers should be prepared to guide current and aspiring practitioners of rough sex, helping them understand potential benefits, risks, and age- and gender-related differences.



https://doi.org/10.1111/psrh.12267
Naumann, Clemens; Carlesi, Tommaso; Otto, Henning; Cierpka, Christian; Laboureur, Delphine
Dynamic characterization of Fiber Bragg Grating temperature sensors. - In: Experimental thermal and fluid science, Bd. 156 (2024), 111222, S. 1-10

To reliably characterize fast dynamic heat transfer mechanisms, fast-response temperature sensors are crucial, including knowledge about the temporal response. In this paper, the dynamic behavior of a Fiber Bragg Grating temperature sensor is investigated and compared to different types of fast-response thermocouples using two different experimental dynamic characterization methods. A temperature step is generated by either plunging the sensor into a fluid or exposing it to a fluid droplet at different temperatures. The step response is evaluated to determine the sensor response time. Calibration runs are performed for a silica-based 0.1 mm FBG sensor, as well as for 0.16 mm and 0.8 mm exposed tip and 0.25 mm sheathed tip type K thermocouples. Water, glycerin, oil and GaInSn were used to cover a broad range of applications regarding different thermal diffusivities and viscosities. The FBG sensor showed the shortest response times compared to the thermocouples, ranging from 60 ms in oil down to 3 ms in liquid metal, which is 20% up to 70% faster compared to a 0.25 mm sheathed tip type K thermocouple. Additional plunging calibration runs of the FBG sensor were performed in a ternary nitrate molten salt mixture (HITEC) to determine its overall and dynamic behavior in corrosive fluids at elevated temperatures. It turns out that the FBG sensor is not affected by the molten salt and shows similar response times to those measured in water. Regarding the characterization methods, both techniques show reproducible results, even though the droplet method is inapplicable for sensors with higher heat capacity or lower thermal conductivity than the calibration fluid. Furthermore, splashing effects for fluids with low viscosity reduce the reliability of the droplet method. The results also show that a dynamic characterization is indispensable for temperature measurements with high temporal resolution because the response time depends on the sensor size and the heat transfer coefficient between sensor and surrounding, which in turn depends on the sensor type, fluid properties and the flow parameters.



https://doi.org/10.1016/j.expthermflusci.2024.111222
Zhao, Yuguo; Björk, Emma M.; Yan, Yong; Schaaf, Peter; Wang, Dong
Recent progress in transition metal based catalysts and mechanism analysis for alcohol electrooxidation reactions. - In: Green chemistry, ISSN 1463-9270, Bd. 26 (2024), 9, S. 4987-5003

In order to address energy and environmental challenges effectively, there is a need to promote renewable energy-driven electrochemical conversion technologies, particularly electrosynthesis. Electrosynthesis has the potential to convert abundant molecules into valuable chemicals and fuels. However, the widespread adoption of electrosynthesis is often hindered by the slow oxygen evolution reaction (OER). To overcome this limitation, we can employ the more efficient alcohol electrooxidation reaction (AOR), utilizing renewable biomass-derived alcohols as an alternative to OER for producing high-value chemicals. Consequently, the development of efficient AOR catalysts, in conjunction with cathodic reduction reactions (hydrogen evolution, oxygen, and nitrogen electroreduction, etc.), is crucial for sustainable and environmentally-friendly advancements. A thorough understanding of AOR mechanisms is essential for catalyst design and can be achieved through the utilization of in situ characterization techniques and density functional theory (DFT) calculations. This review summarizes recent progress in AOR catalysts, with a particular focus on the electrooxidation of monohydric alcohols, polyols, and associated studies on reaction mechanisms. Additionally, the review identifies key factors impeding AOR development and provides insights into future prospects.



https://doi.org/10.1039/D4GC00227J
Arévalo Arboleda, Stephanie; Conde, Melisa; Döring, Nicola; Raake, Alexander
Introducing personas and scenarios to highlight older adults' perspectives on robot-mediated communication. - In: HRI '24 companion, (2024), S. 209-213

Little is known about the expectations of older adults (60+ years old) in robot-mediated communication when leaving aside care-related activities. To bridge this gap, we carried out 30 semi-structured interviews with older adults to explore their experiences and expectations related to technology-mediated communication. We present the results of the collected data through personas that portray three archetype users, Conny Connected, Stephan Skeptical, and Thomas TechFan. These personas are presented in a specific communication scenario with individual goals that go beyond mere communication, such as the desire for closeness (Conny Connected), a problem-free experience (Stephan Skeptical), and exploring affordances of telepresence robots (Thomas Tech-Fan). Also, we provide two considerations when aiming at positive experiences for older adults with robots: balance generalizable aspects and individual needs and identify and challenge preconceptions of telepresence robots.



https://doi.org/10.1145/3610978.3640659
Zeußel, Lisa; Chowdhary, Shefali; Wu, Haocheng; Kumar, Vipan; Singh, Sukhdeep
Sustainable harnessing of waste polycarbonate for synthesizing activated furans to generate Stenhouse adducts on polymer surface. - In: Chemistry, ISSN 1861-471X, Bd. 19 (2024), 13, e202400369, S. 1-11

Plastics are versatile materials, offering lightweight, durable, and affordable solutions across various industries. However, their non-degradable nature poses challenges by end of their life. This study presented an innovative carbonyl extraction method to utilize waste poly(bisphenol A carbonate) (PC) as reaction precursor to synthesis of activated furan as precursor for photoswitchable Stenhouse adducts. This innovative chemical strategy not only generated N,N’-functionalized barbiturates but also provided an eco-friendly and cost-effective alternative to traditional synthesis methods. The method presented hereby not only promotes sustainability by repurposing waste polycarbonate as carbonyl equivalent under green conditions but also yielded reusable bisphenol A (BPA). Furthermore, the derived activated furans exhibited their functionality by forming colored donor-acceptor Stenhouse adducts (DASAs) on aminated polymer surfaces. This work demonstrated a transition from a linear plastics economy toward a circular one, highlighting the potential of plastic waste as a resource for creating materials with improved properties.



https://doi.org/10.1002/asia.202400369
Jaekel, Konrad; Riegler, Sascha Sebastian; Sauni Camposano, Yesenia Haydee; Matthes, Sebastian; Glaser, Marcus; Bergmann, Jean Pierre; Schaaf, Peter; Gallino, Isabella; Müller, Jens; Bartsch, Heike
Influence of increasing density of microstructures on the self-propagating reaction of Al/Ni reactive nanoscale multilayers. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, insges. 21 S.

Surface structuring methods are crucial in semiconductor manufacturing, as they enable the creation of intricate structures on the semiconductor surface, influencing the material’s electrical, mechanical, and chemical properties. This study employs one such structuring method known as reactive ion etching to create black Si structures on silicon substrates. After thermal oxidation, their influence on the reaction of Al/Ni nanoscale multilayers is. For this purpose, various densities of thermally oxidized black Si structures are investigated. It reveals distinct reactive behaviors without corresponding differences in energy release during differential scanning calorimetry measurements. Higher oxidized black Si structure densities result in elevated temperatures and faster reaction propagation, showing fewer defects and reduced layer connections in cross-sectional analyses. The properties of the reactive multilayers on high structure density show the same performance as a reaction on flat thermal SiO2, causing delamination when exceeding 23 structures per µm2. Conversely, lower structure density ensures attachment of reactive multilayers to the substrate due to an increased number of defects, acting as predetermined breaking points for the AlNi alloy. By establishing the adhesion between the reacted multilayer and the substrate, surface structuring could lead to a potential increase in bond strength when using reactive multilayers for bonding.



https://doi.org/10.1002/adem.202302225
Matthes, Sebastian; Glaser, Marcus; Vardo, Emina; Sauni Camposano, Yesenia Haydee; Jaekel, Konrad; Bergmann, Jean Pierre; Schaaf, Peter
Tailoring the reaction path: external crack initiation in reactive Al/Ni multilayers. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2302271, S. 1-6

The influence of intentionally externally induced cracks in reactive Al/Ni multilayer systems is investigated. These cracks affect the reaction dynamics and enable tailoring of the reaction path and the overall velocity of the reaction front. The influence of layer variations onto mechanical crack formation and resulting reaction behavior are investigated. High-speed camera imaging shows the meandering propagation of the reaction front along the crack paths. Therefore, the mechanical cracking process significantly changes the total velocity of the reaction front and thus offers a possibility to control the self-propagating high-temperature synthesis process. It is shown that the phase formation remains unaffected despite the applied strains and cracks. This favorable stability in phase formation ensures predictability and provides insight into the adaptation of RMS for precision applications in joints. The results expand the understanding of mechanical cracking as a tool to influence high-temperature synthesis in reactive multilayer coatings and provide an opportunity to expand the range of applications.



https://doi.org/10.1002/adem.202302271
Glaser, Marcus; Ehlich, Kai; Matthes, Sebastian; Hildebrand, Jörg; Schaaf, Peter; Bergmann, Jean Pierre
Influence of metal surface structures on composite formation during polymer-metal-joining based on reactive Al/Ni multilayer foil. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, insges. 34 S.

Progressive developments in the field of lightweight construction and engineering demand continuous substitution of metals with suitable polymers. However, the combination of dissimilar materials results in a multitude of challenges based on different chemical and physical material properties. Reactive multilayer systems offer a promising joining method for flexible and low-distortion joining of dissimilar joining partners with an energy source introduced directly into the joining zone. Within this publication, hybrid lap joints between semi-crystalline polyamide 6 and surface-structured austenitic steel X5CrNi18-10 (EN 1.4301) were joined using reactive Al/Ni multilayer foils of the type Indium-NanoFoil®. Main objective is to examine possibilities of influencing crack initiation in the foil plane by variation of joining pressure and different metal surface structures with regard to geometry, density and orientation. Thus, the position of foil cracks is superimposed onto the metal structure and associated filling with molten plastic is improved. Consequently, characterisation of occurring crack positions as function of joining pressure and metal structure, analysis of the composite in terms of structural filling and joint strength as well as possible causes of crack initiation are evaluated.



https://doi.org/10.1002/adem.202302254
Mejia Chueca, Maria del Carmen; Winter, Andreas; Abdi, Azadeh; Baumer, Christoph; Ispas, Adriana; Stich, Michael; Riegler, Sascha; Ecke, Gernot; Isaac, Nishchay Angel; Graske, Marcus; Gallino, Isabella; Schaaf, Peter; Jacobs, Heiko O.; Bund, Andreas
A novel method for preparation of Al-Ni reactive coatings by incorporation of Ni nanoparticles into an Al matrix fabricated by electrodeposition in AlCl3:1-eethyl-3-methylimidazolium chloride (1.5:1) ionic liquid containing Ni nanoparticles. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2302217, S. 1-17

Al/Ni reactive coatings are fabricated via electrochemical deposition (ECD) at different applied voltages for reactive bonding application. AlCl3:1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) (1.5:1) ionic liquid electrolyte is used as source of Al, whereas Ni is in the bath and incorporated into final coatings as nanoparticles (NPs). Scanning electron microscopy and Auger electron spectroscopy reveal a homogeneous Ni particle dispersion, as well as a high amount of particle incorporation into the Al matrix. A maximum of 37 wt% (22 at%) of Ni is detected via atomic absorption spectroscopy in the Al/Ni coating deposited at −0.1 V from an electrolyte containing 20 g L−1 of Ni NPs. Previous literature show that for bonding application an ideal concentration is around 50 at% of Ni and 50 at% Al. However, this is achieved using high vacuum, time-consuming processes, and costly techniques like evaporation and magnetron sputtering. The ECD used in this work represents a more cost-efficient approach which is not reported up to date for the aforementioned application. The reactivity of the coatings is confirmed by Differential scanning calorimetry. Herein, an exothermic reaction is detected upon the mixing of Al and Ni occurring at high temperatures.



https://doi.org/10.1002/adem.202302217
Qian, Yudan; Zhou, Zhiming; Zhang, Qingcheng; Zhao, Huaping; Chen, Heng; Han, Jintong; Wan, Haiting; Jin, Huile; Wang, Shun; Lei, Yong
Boosting the energy density of bowl-like MnO2carbon through lithium-intercalation in a high-voltage asymmetric supercapacitor with “water-in-salt” electrolyte. - In: Small, ISSN 1613-6829, Bd. 0 (2024), 0, 2310037, S. 1-11

Highly concentrated “‘water-in-salt”’ (WIS) electrolytes are promising for high-performance energy storage devices due to their wide electrochemical stability window. However, the energy storage mechanism of MnO2 in WIS electrolytes-based supercapacitors remains unclear. Herein, MnO2 nanoflowers are successfully grown on mesoporous bowl-like carbon (MBC) particles to generate MnO2/MBC composites, which not only increase electroactive sites and inhibit the pulverization of MnO2 particles during the fast charging/discharging processes, but also facilitate the electron transfer and ion diffusion within the whole electrode, resulting in significant enhancement of the electrochemical performance. An asymmetric supercapacitor, assembled with MnO2/MBC and activated carbon (AC) and using 21 m LiTFSI solution as the WIS electrolyte, delivers an ultrahigh energy density of 70.2 Wh kg−1 at 700 W kg−1, and still retains 24.8 Wh kg−1 when the power density is increased to 28 kW kg−1. The ex situ XRD, Raman, and XPS measurements reveal that a reversible reaction of MnO2 + xLi+ + xe−↔LixMnO2 takes place during charging and discharging. Therefore, the asymmetric MnO2/MBC//AC supercapacitor with LiTFSI electrolyte is actually a lithium-ion hybrid supercapacitor, which can greatly boost the energy density of the assembled device and expand the voltage window.



https://doi.org/10.1002/smll.202310037
Nikiruy, Kristina; Perez, Eduardo; Baroni, Andrea; Reddy, Keerthi Dorai Swamy; Pechmann, Stefan; Wenger, Christian; Ziegler, Martin
Blooming and pruning: learning from mistakes with memristive synapses. - In: Scientific reports, ISSN 2045-2322, Bd. 14 (2024), 7802, S. 1-11

Blooming and pruning is one of the most important developmental mechanisms of the biological brain in the first years of life, enabling it to adapt its network structure to the demands of the environment. The mechanism is thought to be fundamental for the development of cognitive skills. Inspired by this, Chialvo and Bak proposed in 1999 a learning scheme that learns from mistakes by eliminating from the initial surplus of synaptic connections those that lead to an undesirable outcome. Here, this idea is implemented in a neuromorphic circuit scheme using CMOS integrated HfO2-based memristive devices. The implemented two-layer neural network learns in a self-organized manner without positive reinforcement and exploits the inherent variability of the memristive devices. This approach provides hardware, local, and energy-efficient learning. A combined experimental and simulation-based parameter study is presented to find the relevant system and device parameters leading to a compact and robust memristive neuromorphic circuit that can handle association tasks.



https://doi.org/10.1038/s41598-024-57660-4
Korder, Kristina; Cao, Hao; Salomons, Elad; Ostfeld, Avi; Li, Pu
Simultaneous minimization of water age and pressure in water distribution systems by pressure reducing valves. - In: Water resources management, ISSN 1573-1650, Bd. 0 (2024), 0, insges. 19 S.

Pressure reducing valves (PRVs) are essentially used to reduce operational pressures in water distribution systems (WDSs) to minimize water leakage. However, water age in a WDS is an important variable describing the water quality and should be kept as low as possible. Therefore, the aim of this study is to investigate the possibility and potential of simultaneously minimizing both pressure and water age by using PRVs. To determine the optimal location and setting of PRVs, a mixed-integer nonlinear programming (MINLP) problem is formulated with minimization of the sum of the weighted total water age and pressure as the objective function, where the weighting factor can be defined by the user’s preference. The equality constraints consist of the hydraulic equations and water age functions to describe pressure and water age in the distribution network, while the inequality constraints ensure them in the defined operating ranges, respectively. Applying the proposed approach to two case studies, the results show that both water age and pressure can indeed be significantly reduced by the optimized position and setting of the PRVs.



https://doi.org/10.1007/s11269-024-03828-6
Hannappel, Thomas; Shekarabi, Sahar; Jaegermann, Wolfram; Runge, Erich; Hofmann, Jan Philipp; Krol, Roel van de; May, Matthias M.; Paszuk, Agnieszka; Hess, Franziska; Bergmann, Arno; Bund, Andreas; Cierpka, Christian; Dreßler, Christian; Dionigi, Fabio; Friedrich, Dennis; Favaro, Marco; Krischok, Stefan; Kurniawan, Mario; Lüdge, Kathy; Lei, Yong; Roldán Cuenya, Beatriz; Schaaf, Peter; Schmidt-Grund, Rüdiger; Schmidt, W. Gero; Strasser, Peter; Unger, Eva; Montoya, Manuel Vasquez; Wang, Dong; Zhang, Hongbin
Integration of multijunction absorbers and catalysts for efficient solar-driven artificial leaf structures: a physical and materials science perspective. - In: Solar RRL, ISSN 2367-198X, Bd. 8 (2024), 11, 2301047, S. 1-49

Artificial leaves could be the breakthrough technology to overcome the limitations of storage and mobility through the synthesis of chemical fuels from sunlight, which will be an essential component of a sustainable future energy system. However, the realization of efficient solar-driven artificial leaf structures requires integrated specialized materials such as semiconductor absorbers, catalysts, interfacial passivation, and contact layers. To date, no competitive system has emerged due to a lack of scientific understanding, knowledge-based design rules, and scalable engineering strategies. Here, we will discuss competitive artificial leaf devices for water splitting, focusing on multi-absorber structures to achieve solar-to-hydrogen conversion efficiencies exceeding 15%. A key challenge is integrating photovoltaic and electrochemical functionalities in a single device. Additionally, optimal electrocatalysts for intermittent operation at photocurrent densities of 10-20 mA cm^-2 must be immobilized on the absorbers with specifically designed interfacial passivation and contact layers, so-called buried junctions. This minimizes voltage and current losses and prevents corrosive side reactions. Key challenges include understanding elementary steps, identifying suitable materials, and developing synthesis and processing techniques for all integrated components. This is crucial for efficient, robust, and scalable devices. Here, we discuss and report on corresponding research efforts to produce green hydrogen with unassisted solar-driven (photo-)electrochemical devices. This article is protected by copyright. All rights reserved.



https://doi.org/10.1002/solr.202301047
Philipp, Friedrich; Schaller, Manuel; Worthmann, Karl; Peitz, Sebastian; Nüske, Feliks
Error bounds for kernel-based approximations of the Koopman operator. - In: Applied and computational harmonic analysis, ISSN 1096-603X, Bd. 71 (2024), 101657, S. 1-25

We consider the data-driven approximation of the Koopman operator for stochastic differential equations on reproducing kernel Hilbert spaces (RKHS). Our focus is on the estimation error if the data are collected from long-term ergodic simulations. We derive both an exact expression for the variance of the kernel cross-covariance operator, measured in the Hilbert-Schmidt norm, and probabilistic bounds for the finite-data estimation error. Moreover, we derive a bound on the prediction error of observables in the RKHS using a finite Mercer series expansion. Further, assuming Koopman-invariance of the RKHS, we provide bounds on the full approximation error. Numerical experiments using the Ornstein-Uhlenbeck process illustrate our results.



https://doi.org/10.1016/j.acha.2024.101657
Freisinger, Elena; McCarthy, Ian P.
What fails and when? : a process view of innovation failure. - In: Technovation, Bd. 133 (2024), 102995, S. 1-14

Research on innovation failure has proliferated lately but with little theoretical attention given to the diversity of the concept. Using process theorizing, we present a model and propositions to understand how a firm's anticipation and value toward failure depends on the type of failure (task versus outcome) and the phase (divergent versus convergent) and point (early versus later) ‘within’ the process that the failure occurs. Using the anticipation-value stances, we then present a typology of four modes of innovation failure that can arise ‘from’ task and outcomes failure in the innovation process. The four modes (and associated learning response) are unsolicited failures (prevent-alert-eliminate); hazardous failures (predict-modify-mitigate); fortuitous failures (probe-expose-extrapolate); and excursive failures (facilitate-analyze-harness). To help explain the ideas in our process model and typology, we use the well-known IDEO shopping cart innovation project as an illustrative example. Together, these contributions provide contingency oriented insights on how failure varies and journeys within and from the innovation process, which helps researchers and managers to better understand the related causes, effects and learning responses.



https://doi.org/10.1016/j.technovation.2024.102995
Petrich, Martin; Kletzin, Ulf; Krehan, Tom-Luis; Feld, Julius; Otto, Christian
Design methodology for fiber-reinforced polymer composite springs and experimental study on a volute spring. - In: Composites and advanced materials, ISSN 2634-9833, Bd. 33 (2024), S. 1-16

Fiber-reinforced polymer (FRP) composites are particularly suitable for spring applications due to numerous advantages like lightweight design, intrinsic damping, or chemical resistance. Although there are many studies on the properties of FRPs and even some on springs made out of these materials, there is no holistic method for FRP spring design. Therefore, this article focuses on a new approach that combines all relevant design steps. This includes a spring-related overview of requirements and associated FRP properties, as well as recommendations regarding material and spring type selection with a specialization on polymer composite volute springs. Thereupon, a mountain bike rear suspension spring was designed and produced. These carbon fiber-reinforced polymer (CFRP) lightweight spring, which weighs only half of the metal spring, was examined in static and cyclic experiments. Important results of the tests are a lower spring rate than theoretically expected as well as a loss of stiffness of the spring of about 25% after 25,000 full deflections just before failure. Downhill riding tests were carried out and showed comparable driving characteristics as when using conventional steel springs. The research is a contribution to FRP spring design considerations as well as to extend the range of applications for composite springs, and especially volute springs, in the future.



https://doi.org/10.1177/26349833241245134
Zheng, Niannian; Luan, Xiaoli; Shardt, Yuri A. W.; Liu, Fei
Dynamic-controlled Bayesian network for process pattern modeling and optimization. - In: Industrial & engineering chemistry research, ISSN 1520-5045, Bd. 63 (2024), 15, S. 6674-6684

Capturing the current statistical features of a process and its dynamic evolution is important for controlling and monitoring its overall operational status. In terms of capturing the process dynamics, existing probabilistic latent-variable methods mostly consider autoregressive relationships, and thus, the causality from the control inputs to the pattern, or key hidden variable, remains unmodeled or implicit. To bridge this gap, a model structured by a newly designed dynamic-controlled Bayesian network (DCBN) is proposed in this paper for pattern modeling, especially pattern control and optimization. Significantly, the innovation and advantage of the DCBN lie in explicitly quantifying the impulse response of the pattern under control inputs. As well, the expectation-maximization algorithm is specially designed for learning the DCBN model. Finally, a new framework for pattern-based process control and optimization is presented in which online pattern filtering and control can be implemented. A case study on the combustion process from an industrial boiler illustrates the advantages of the proposed method in that it can capture the controlled dynamics of the process and achieve optimization by tracking the pattern set point or trajectory.



https://doi.org/10.1021/acs.iecr.3c04391
Pikushina, Alena; Centeno, Luis Fernando; Stehr, Uwe; Jacobs, Heiko O.; Hein, Matthias
Electrical lengths and phase constants of stretchable coplanar transmission lines at GHz frequencies. - In: Flexible and printed electronics, ISSN 2058-8585, Bd. 9 (2024), 1, 015005, S. 1-12

Elastic, bendable and stretchable electronics establish a new and promising area of multi-physics engineering for a variety of applications, e.g. on wearables or in complex-shaped machine parts. While the area of metamorphic electronics has been investigated comprehensively, the behavior at radio frequencies (RFs), especially in the GHz range, is much less well studied. The mechanical deformation of the soft substrates, for instance, due to stretching, changes the geometrical dimensions and the electrical properties of RF transmission lines. This effect could be desirable in some cases, e.g. for smart devices with shape-dependent transmission or radiation characteristics, or undesirable in other cases, e.g. in feed and distribution networks due to the variable electrical lengths and thus phase variations. This contribution describes the results of a systematic study of the broadband RF properties of coplanar transmission lines on Ecoflex® substrates, based on numerical simulations and experimental data. Two types of stretchable transmission line structures were studied: Meander- and circular ring-segmented lines. Modeling and simulation were performed combining a 2D circuit simulation software with electromagnetic full-wave simulations. The experimental part of the work included the fabrication of metamorphic substrates metallized with thin copper layers and systematic measurements of the electrical lengths and phase constants of coplanar waveguides in the frequency range from 1 to 5 GHz based on vector network analysis for different stretching levels. With the given substrate technology, we succeeded in demonstrating stretchability up to a level of 21%, while the theoretical limit is expected at 57%. The meander- and circular-shaped line structures revealed markedly different sensitivities to the stretching level, which was lower for circular structures compared to the meander structures by approximately a factor of three.



https://doi.org/10.1088/2058-8585/ad1efd
Petrich, Martin; Kletzin, Ulf
Practical fatigue strength diagrams for compression springs based on the FKM-guideline “Analytic Strength Assessment for Springs“. - In: International journal of fatigue, Bd. 183 (2024), 108273, S. 1-8

Metal springs are used extensively in technical products. The mathematical relationships and Goodman diagrams contained in the DIN EN 13906-1 standard form the essential basis for the design and calculation of cylindrical helical compression springs. They are used not only nationally, but internationally in the spring industry and by spring users. However, the diagrams are more than 50 years old and no longer reflect the current status of modern spring materials and spring manufacturing technologies. This results in great uncertainty for users of the standard, which currently has to be compensated by costly fatigue tests. In order to overcome the problems, the research project IGF 19693 aimed to renew the Goodman diagrams of the DIN EN 13906-1 standard in accordance with the state of spring technology. Therefore, the FKM guideline “Analytic Strength Assessment for Springs and Spring Elements“ was used to calculate permissible fatigue strength values for standard springs. Additionally, an extensive experimental program was carried out with fatigue tests on cold-formed helical compression springs to validate the calculations. The main results of the project are presented in this manuscript, which strengthens SMEs in designing competitive springs, which they can offer in a shorter time and at a lower cost due to lower development costs.



https://doi.org/10.1016/j.ijfatigue.2024.108273
Schwarz, Andreas; Unselt, Janina Jacqueline
Rage against the machine? : framing societal threat and efficacy in YouTube videos about artificial intelligence. - In: Risk analysis, ISSN 1539-6924, Bd. 0 (2024), 0, S. 1-19

Artificial intelligence (AI) has become a part of the mainstream public discourse beyond expert communities about its risks, benefits, and need for regulation. In particular, since 2014, the news media have intensified their coverage of this emerging technology and its potential impact on most domains of society. Although many studies have analyzed traditional media coverage of AI, analyses of social media, especially video-sharing platforms, are rare. In addition, research from a risk communication perspective remains scarce, despite the widely recognized potential threats to society from many AI applications. This study aims to detect recurring patterns of societal threat/efficacy in YouTube videos, analyze their main sources, and compare detected frames in terms of reach and response. Using a theoretical framework combining framing and risk communication, the study analyzed the societal threat/efficacy attributed to AI in easily accessible YouTube videos published in a year when public attention to AI temporarily peaked (2018). Four dominant AI frames were identified: the balanced frame, the high-efficacy frame, the high-threat frame, and the no-threat frame. The balanced and no-threat frames were the most prevalent, with predominantly positive and neutral AI narratives that neither adequately address the risks nor the necessary societal response from a normative risk communication perspective. The results revealed the specific risks and benefits of AI that are most frequently addressed. Video views and user engagement with AI videos were analyzed. Recommendations for effective AI risk communication and implications for risk governance were derived from the results.



https://doi.org/10.1111/risa.14299
Sharifi Ghazijahani, Mohammad; Cierpka, Christian
Spatio-temporal dynamics of superstructures and vortices in turbulent Rayleigh-Bénard convection. - In: Physics of fluids, ISSN 1089-7666, Bd. 36 (2024), 3, 035120, S. 035120-1-035120-19

Understanding turbulent thermal convection is essential for modeling many natural phenomena. This study investigates the spatiotemporal dynamics of the vortical structures in the mid-plane of turbulent Rayleigh-Bénard convection in SF6 via experiments. For this, a Rayleigh-Bénard cell of aspect ratio 10 is placed inside a pressure vessel and pressurized up to 1, 1.5, and 2.5 bar in order to reach Rayleigh numbers of Ra = 9.4 × 10^5, 2.0 × 10^6, and 5.5 × 10^6, respectively. For all three cases, the Prandtl number is Pr = 0.79 and Δ T ≈ 7 K. Then, stereoscopic particle image velocimetry is conducted to measure the three velocity components in the horizontal-mid-plane for 5.78 × 10^3 free fall times. For the given aspect ratio, the flow is no longer dominated by the side walls of the cell and turbulent superstructures that show a two-dimensional repetitive organization form. These superstructures show diverse shapes with faster dissipation rates as Ra increases. Out-of-plane vortices are the main feature of the flow. As Ra increases, the number of these vortices also increases, and their size shrinks. However, their total number is almost constant for each Ra through the measurement period. Furthermore, their occurrence is random and does not depend on whether the flow is upward-heated, downward-cooled, or horizontally directed. Vortex tracking was applied to measure lifetime, displacement, and traveled distance of these structures. The relation between lifetime and traveled distance is rather linear. Interestingly, in the vortex centers, the out-of-plane momentum transport is larger in comparison to the bulk flow. Therefore, these vortices will play a major role in the heat transport in such flows.



https://doi.org/10.1063/5.0191403
Wunsch, Lennard; Görner Tenorio, Christian; Anding, Katharina; Golomoz, Andrei; Notni, Gunther
Data fusion of RGB and depth data with image enhancement. - In: Journal of imaging, ISSN 2313-433X, Bd. 10 (2024), 3, 73, S. 1-17

Since 3D sensors became popular, imaged depth data are easier to obtain in the consumer sector. In applications such as defect localization on industrial objects or mass/volume estimation, precise depth data is important and, thus, benefits from the usage of multiple information sources. However, a combination of RGB images and depth images can not only improve our understanding of objects, capacitating one to gain more information about objects but also enhance data quality. Combining different camera systems using data fusion can enable higher quality data since disadvantages can be compensated. Data fusion itself consists of data preparation and data registration. A challenge in data fusion is the different resolutions of sensors. Therefore, up- and downsampling algorithms are needed. This paper compares multiple up- and downsampling methods, such as different direct interpolation methods, joint bilateral upsampling (JBU), and Markov random fields (MRFs), in terms of their potential to create RGB-D images and improve the quality of depth information. In contrast to the literature in which imaging systems are adjusted to acquire the data of the same section simultaneously, the laboratory setup in this study was based on conveyor-based optical sorting processes, and therefore, the data were acquired at different time periods and different spatial locations. Data assignment and data cropping were necessary. In order to evaluate the results, root mean square error (RMSE), signal-to-noise ratio (SNR), correlation (CORR), universal quality index (UQI), and the contour offset are monitored. With JBU outperforming the other upsampling methods, achieving a meanRMSE = 25.22, mean SNR = 32.80, mean CORR = 0.99, and mean UQI = 0.97.



https://doi.org/10.3390/jimaging10030073
Shekhawat, Deepshikha; Sindhani, Kashish; Raheja, Vishal Amarbhai; Baloochi, Mostafa; Isaac, Nishchay Angel; Pezoldt, Jörg
Modelling reaction transfer velocities in disconnected compact heterogeneous multilayer reactive material systems. - In: MRS advances, ISSN 2059-8521, Bd. 0 (2024), 0, S. 1-6

The tuning of the self-propagating reaction is studied theoretically by introducing a non-reactive material between two reactive material elements. For the study, the Ni/Al bilayer system was chosen. The Ni/Al elements were placed on a silicon wafer covered with a 1-µm-thick silicon dioxide. The spaces between the multilayer reactive material elements were filled with different non-reactive materials covering a wide range of thermal properties. On top of this heterogeneous layer, a 1-µm-thick sealing layer was placed consisting of the filler material. The carried out two-dimensional simulations demonstrated that embedding material allows to scale the ignition transfer time and the heat propagation velocity. For example, for a transfer length of 1 µm, the ignition time can be tuned from nano- to microseconds. Consequently, in contrast to previous results embedding materials allow scaling the properties of the self-propagating reaction in heterogeneous reactive material systems.



https://doi.org/10.1557/s43580-024-00822-3
Drücker, Svenja; Lanza, Lukas; Berger, Thomas; Reis, Timo; Seifried, Robert
Experimental validation for the combination of funnel control with a feedforward control strategy. - In: Multibody system dynamics, ISSN 1573-272X, Bd. 0 (2024), 0, S. 1-19

Current engineering design trends, such as lightweight machines and human-machine interaction, often lead to underactuated systems. Output trajectory tracking of such systems is a challenging control problem. Here, we use a two-design-degree of freedom control approach by combining funnel feedback control with feedforward control based on servo-constraints. We present experimental results to verify the approach and demonstrate that the addition of a feedforward controller mitigates drawbacks of the funnel controller. We also present new experimental results for the real-time implementation of a feedforward controller based on servo-constraints on a minimum phase system.



https://doi.org/10.1007/s11044-024-09976-2
Janke, Mario; Mäder, Patrick
7 dimensions of software change patterns. - In: Scientific reports, ISSN 2045-2322, Bd. 14 (2024), 6141, S. 1-17

Evolving software is a highly complex and creative problem in which a number of different strategies are used to solve the tasks at hand. These strategies and reoccurring coding patterns can offer insights into the process. However, they can be highly project or even task-specific. We aim to identify code change patterns in order to draw conclusions about the software development process. For this, we propose a novel way to calculate high-level file overarching diffs, and a novel way to parallelize pattern mining. In a study of 1000 Java projects, we mined and analyzed a total of 45,000 patterns. We present 13 patterns, showing extreme points of the 7 pattern categories we identified. We found that a large number of high-level change patterns exist and occur frequently. The majority of mined patterns were associated with a specific project and contributor, where and by whom it was more likely to be used. While a large number of different code change patterns are used, only a few, mostly unsurprising ones, are common under all circumstances. The majority of code change patterns are highly specific to different context factors that we further explore.



https://doi.org/10.1038/s41598-024-54894-0
Honecker, Maria Christine; Gernandt, Hannes; Wulff, Kai; Trunk, Carsten; Reger, Johann
Feedback rectifiable pairs and stabilization of switched linear systems. - In: Systems & control letters, ISSN 1872-7956, Bd. 186 (2024), 105755, S. 1-10

We address the feedback design problem for switched linear systems. In particular we aim to design a switched state-feedback such that the resulting closed-loop subsystems share the same eigenstructure. To this effect we formulate and analyse the feedback rectification problem for pairs of matrices. We present necessary and sufficient conditions for the feedback rectifiability of pairs for two subsystems and give a constructive procedure to design stabilizing state-feedback for a class of switched systems. In particular the proposed algorithm provides sets of eigenvalues and corresponding eigenvectors for the closed-loop subsystems that guarantee stability for arbitrary switching. Several examples illustrate the characteristics of the problem considered and the application of the proposed design procedure.



https://doi.org/10.1016/j.sysconle.2024.105755
Byrski, Witold; Drapała, Michał; Byrski, J&hlink;edrzej; Noack, Matti; Reger, Johann
Comparison of LQR with MPC in the adaptive stabilization of a glass conditioning process using soft-sensors for parameter identification and state observation. - In: Control engineering practice, ISSN 1873-6939, Bd. 146 (2024), 105884, S. 1-11

The paper presents the comparison of two different continuous-time adaptive control strategies applied to the temperature stabilization of molten glass during conditioning. Both control methods include on-line linear continuous-time model parameter identification using a nonstandard procedure based on the modulating functions method. The related control task is of great practical importance because it directly affects the quality of manufactured glass containers. The molten glass temperature must be stabilized with accuracy of about 1C&ring; which can be very difficult. At the core of this work, the synthesis of a nonstandard adaptive control procedure is described that consists of a linear quadratic regulator (LQR) being fed with process parameters and state estimates. These new state estimates are generated with a special transform and reconstructed by a special type of modulating function state observer consisting of two modulating function based soft-sensors which rely on a continuous-time model. However, an equally important issue of this investigation is the efficiency and accuracy of the algorithm. To this end, the described stabilization method will be compared with a standard continuous-time model predictive control (MPC) approach that was used in the authors’ previous research on the continuous molten glass temperature stabilization in a single glass forehearth zone. Simulation results based on experimental calibration data are presented and compared for these two approaches. It turns out that the first method with LQR is simpler than the MPC approach while maintaining the same level of accuracy and quality of control.



https://doi.org/10.1016/j.conengprac.2024.105884
Jaziri, Nesrine; Schulz, Alexander; Bartsch, Heike; Müller, Jens; Tounsi, Fares
A novel 2-in-1 heat management and recovery system for sustainable electronics. - In: Energy conversion and management, ISSN 0196-8904, Bd. 303 (2024), 118171, S. 1-12

Overheating poses major challenges in miniaturized electronics, especially as their power consumption increases. For this reason, thermal management is a necessity for efficient electronics, and its optimization is a central task in the design especially for miniaturized compact electronics. On the other hand, recovering this waste energy could be beneficial for battery-free electronics such as wireless sensors and devices located in remote environments, where the charging or changing of batteries are challenging and delicate tasks. Furthermore, batteries are known for their storage capacity degradation over time and environmental pollution. This paper presents the design, development, demonstration, and validation of an innovative 2-in-1 heat management and recovery system for autonomous electronic devices. The design incorporates the use of thermal vias as in-package heat management and vertical thermocouples, enabling simultaneously management and recovery of the heat emitted from a Si-chip. The proposed design is fabricated in Low Temperature Co-fired Ceramic (LTCC) technology, allowing the creation of a monolithic package containing miniaturized multilayer microvias in the range of 90 µm using different materials to act as embedded thermal management and vertical thermocouples, simultaneously. The design consists of 20 lateral (Ag/Co) and 21 vertical (Ag/AgPd) micro-TEGs connected electrically in series in the system. The hybrid TEG is made by combining thick- and thin-film technologies, favoring the use of different materials and technologies with high power factors for further improvements in the field of thermal energy harvesting. The proposed design allows the management of 67 % of the IC temperature by reducing it from 246 &ring;C to 80 &ring;C using Ag and AgPd thermal vias. At the same time, the system recovers the lost thermal energy to generate 37.5 µW of electrical power at a temperature difference of 58 &ring;C. The proposed approach allows simultaneously transitioning into green and sustainable battery-free electronics and enhances the devicés reliability by maintaining thermal stabilization in a miniaturized devices using a monolithic package.



https://doi.org/10.1016/j.enconman.2024.118171
Oppermann, Hannes; Thelen, Antonia; Haueisen, Jens
Single-trial EEG analysis reveals burst structure during photic driving. - In: Clinical neurophysiology, ISSN 1872-8952, Bd. 159 (2024), S. 66-74

Objective: Photic driving in the human visual cortex evoked by intermittent photic stimulation is usually characterized in averaged data by an ongoing oscillation showing frequency entrainment and resonance phenomena during the course of stimulation. We challenge this view of an ongoing oscillation by analyzing unaveraged data. Methods: 64-channel EEGs were recorded during visual stimulation with light flashes at eight stimulation frequencies between 7.8 and 23 Hz for fourteen healthy volunteers. Time-frequency analyses were performed in averaged and unaveraged data. Results: While we find ongoing oscillations in the averaged data during intermittent photic stimulation, we find transient events (bursts) of activity in the unaveraged data. Both resonance and entrainment occur for the ongoing oscillations in the averaged data and the bursts in the unaveraged data. Conclusions: We argue that the continuous oscillations in the averaged signal may be composed of brief, transient bursts in single trials. Our results can also explain previously observed amplitude fluctuations in averaged photic driving data. Significance: Single-trial analyses might consequently improve our understanding of resonance and entrainment phenomena in the brain.



https://doi.org/10.1016/j.clinph.2024.01.005
Bohm, Sebastian; Runge, Erich
Efficient analytical evaluation of the singular BEM integrals for the three-dimensional Laplace and Stokes equations over polygonal elements. - In: Engineering analysis with boundary elements, ISSN 0955-7997, Bd. 161 (2024), S. 70-77

Singularities in the fundamental solutions pose a mathematical challenge for all applications of the boundary element method, if the source and field point lie on the same element. To avoid complex and error-prone numerical procedures, analytical solutions for the integrals that arise are desirable. In this work, easy and efficiently to implement analytical solutions are presented for the fundamental solutions of the three-dimensional Stokes equation as well as Laplace’s equation. Explicit expressions are derived for general triangular elements using constant shape functions. In addition, options for extending to arbitrary polygonal elements are shown. In particular, the three cases that the incenter, the centroid or the vertices of the triangles are used as source points for the calculation are addressed. The impressive numerical efficiency of the method is demonstrated by explicit examples.



https://doi.org/10.1016/j.enganabound.2024.01.013
Ikegami, Yukino; Tsuruta, Setsuo; Kutics, Andrea; Damiani, Ernesto; Knauf, Rainer
Fast ML-based next-word prediction for hybrid languages. - In: Internet of things and cyber-physical systems, ISSN 2667-3452, Bd. 25 (2024), 101064, S. 1-15

Smartphone users are beyond two billion worldwide. Heavy users of the texting application rely on input prediction to reduce typing effort. In languages based on the Roman alphabet, many techniques are available. However, Japanese text is based on multiple character sets such as Kanji (Chinese-like word symbols), Hiragana and Katakana syllable sets. For its time/labor intensive input, next word prediction is crucial. It is still an open challenge. To tackle this, a hybrid language model is proposed. It integrates a Recurrent Neural Network (RNN) with an n-gram model. RNNs are powerful models for learning long sequences for next word prediction. N-gram models are best at current word completion. Our RNN language model (RNN-LM) predicts the next words. According the “price” of the performance gain paid by a higher time complexity, our model best deploys on a client-server architecture. Heavily-loaded RNN-LM deploys on the server while the n-gram model on the client. Our RNN-LM consists of an input layer equipped with word embedding, an output layer, and hidden layers connected with LSTMs (Long Short-Term Memories). Training is done via BPTT (Back Propagation Through Time). For robust training, BPTT is elaborated by learning rate refinement and gradient norm scaling. To avoid overfitting, the dropout technique is applied except for LSTM. Our novel model is compact (2 LSTMs, 650 units per layer), indeed. Due to synergetic elaboration, it shows 10 % lower perplexity than Zaremba's excellent conventional models in our Japanese text prediction experiment. Our model has been incorporated into IME (Input Method Editor) we call Flick. On the Japanese text input experiment, Flick outperforms Mozc (Google Japanese Input) by 16 % in time and 34 % in the number of keystrokes.



https://doi.org/10.1016/j.iot.2024.101064
Qiu, Jiajia; Duan, Yu; Li, Shaoyuan; Zhao, Huaping; Ma, Wenhui; Shi, Weidong; Lei, Yong
Insights into nano- and micro-structured scaffolds for advanced electrochemical energy storage. - In: Nano-Micro letters, ISSN 2150-5551, Bd. 16 (2024), 1, 130, S. 1-44

Adopting a nano- and micro-structuring approach to fully unleashing the genuine potential of electrode active material benefits in-depth understandings and research progress toward higher energy density electrochemical energy storage devices at all technology readiness levels. Due to various challenging issues, especially limited stability, nano- and micro-structured (NMS) electrodes undergo fast electrochemical performance degradation. The emerging NMS scaffold design is a pivotal aspect of many electrodes as it endows them with both robustness and electrochemical performance enhancement, even though it only occupies complementary and facilitating components for the main mechanism. However, extensive efforts are urgently needed toward optimizing the stereoscopic geometrical design of NMS scaffolds to minimize the volume ratio and maximize their functionality to fulfill the ever-increasing dependency and desire for energy power source supplies. This review will aim at highlighting these NMS scaffold design strategies, summarizing their corresponding strengths and challenges, and thereby outlining the potential solutions to resolve these challenges, design principles, and key perspectives for future research in this field. Therefore, this review will be one of the earliest reviews from this viewpoint.



https://doi.org/10.1007/s40820-024-01341-4
Shekhawat, Deepshikha; Sulman, Muhammad; Breiter, Manuela; Pezoldt, Jörg
Controlling reaction transfer between Al/Ni reactive multilayer elements on substrates. - In: MRS advances, ISSN 2059-8521, Bd. 0 (2024), 0, S. 1-6

Reactive multilayers produce exothermic reaction with definite velocity and maximum temperature after ignition, which are the fundamental properties of the reactive multilayer systems. The generated heat with certain velocity makes it widely used in joining, bonding in the packaging, thermal batteries and many more applications. In this work, a distinct approach for achieving a reaction transfer between the reactive multilayers and different materials is demonstrated which can affect the generated temperature and velocity from the self-propagating properties of the reaction. For these intensions, we fabricated the Al/Ni reactive elements with certain separations between elements which allow to observe the reaction front transfer and emitted temperature in the reaction chain. The created separation between reactive elements are periodical and ordered systems with different thermal conductive properties. The temperature and definite velocity were measured by time-resolved pyrometer and high-speed camera measurements. SEM analysis showed the characteristics of the reaction transfer between reactive multilayer elements. It is predicted that: (I) The reaction front stops at a space with critical length; (II) Reducing heat loss through the substrate supports reaction front propagation through spaces; (III) Thermal property design of the spaces between the reactive elements enables property modification of the self-propagating reaction.



https://doi.org/10.1557/s43580-024-00804-5
Walther, Dominik; Junger, Christina; Schmidt, Leander; Schricker, Klaus; Notni, Gunther; Bergmann, Jean Pierre; Mäder, Patrick
Recurrent autoencoder for weld discontinuity prediction. - In: Journal of advanced joining processes, ISSN 2666-3309, Bd. 9 (2024), 100203, S. 1-12

Laser beam butt welding is often the technique of choice for a wide range of industrial tasks. To achieve high quality welds, manufacturers often rely on heavy and expensive clamping systems to limit the sheet movement during the welding process, which can affect quality. Jiggless welding offers a cost-effective and highly flexible alternative to common clamping systems. In laser butt welding, the process-induced joint gap has to be monitored in order to counteract the effect by means of an active position control of the sheet metal. Various studies have shown that sheet metal displacement can be detected using inductive probes, allowing the prediction of weld quality by ML-based data analysis. The probes are dependent on the sheet metal geometry and are limited in their applicability to complex geometric structures. Camera systems such as long-wave infrared (LWIR) cameras can instead be mounted directly behind the laser to overcome a geometry dependent limitation of the jiggles system. In this study we will propose a deep learning approach that utilizes LWIR camera recordings to predict the remaining welding process to enable an early detection of weld interruptions. Our approach reaches 93.33% accuracy for time-wise prediction of the point of failure during the weld.



https://doi.org/10.1016/j.jajp.2024.100203
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), 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
Domahidi, Emese; Engelmann, Ines; Pentzold, Christian; Puppis, Manuel
Editorial. - In: Publizistik, ISSN 1862-2569, Bd. 69 (2024), 1, S. 1-4

https://doi.org/10.1007/s11616-024-00831-0
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. 9 (2024), 11, 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. 98 (2024), 4, S. 1061-1080

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
Sar&inodot;sakalo&bovko;glu, Aynur;
[Rezension von: Schlüsselwerke der Journalismusforschung]. - In: Publizistik. - Wiesbaden : VS Verl. für Sozialwiss., 2000- , ISSN: 1862-2569 , ZDB-ID: 2273951-8, ISSN 1862-2569, Bd. 69 (2024), 1, S. 107-109

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