TY - JOUR A1 - Monkman, Gareth J. A1 - Sindersberger, Dirk A1 - Prem, Nina T1 - Magnetically enhanced photoconductive high voltage control JF - ISSS Journal of Micro and Smart Systems N2 - The recent surge of interest in electrostatic actuators, particularly for soft robotic applications, has placed increasing demands on high voltage control technology. In this respect, optoelectronic bidirectional switching and analogue regulation of high voltages is becoming increasingly important. One common problem is the leakage current due to dark resistance of the material or device used. Another is the physical size of such elements. However, their ability to provide galvanic separation makes them a very attractive alternative to conventional (wired) semiconductor elements. This paper gives an overview of available methods and devices before introducing a concept based on the combination of photoresistive and magnetoresistive effects in Gallium Arsenide that are potentially applicable to other semiconductor materials. KW - GaAs KW - High voltage actuators KW - Magnetoresistance KW - Opto-sensors KW - Photoconduction KW - Soft robotics Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-30606 N1 - Corresponding author: Gareth J. Monkman VL - 11 SP - 317 EP - 328 PB - Springer Nature ER - TY - JOUR A1 - Monkman, Gareth J. A1 - Striegl, Birgit A1 - Prem, Nina A1 - Sindersberger, Dirk T1 - Electrical Properties of Magnetoactive Boron‐Organo‐Silicon Oxide Polymers JF - Macromolecular Chemistry and Physics N2 - The electrical properties of rheopectic magnetoactive composites comprising boron-organo-silicon oxide dielectric matrices containing carbonyl iron microparticles are presented for the first time. The increase in interfacial magnetocapacitance is seen to greatly exceed that experienced when using conventional elastomeric matrices such as polydimethylsiloxane. In addition to the increase in capacitance, a simultaneous and sharp decrease in the parallel electrical resistance over several orders of magnitude is also observed. The effects are time dependent but repeatable. Potential applications include magnetically controlled frequency dependent devices, magnetic sensor systems, weighting elements for neural networks, etc. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-26488 N1 - Corresponding author: Gareth J. Monkman VL - 221 IS - 4 SP - 1 EP - 8 PB - Wiley ER - TY - JOUR A1 - Prem, Nina A1 - Sindersberger, Dirk A1 - Monkman, Gareth J. T1 - Infrared spectral analysis of low concentration magnetoactive polymers JF - Journal of Applied Polymer Science N2 - This work concerns an area of magnetoactive polymer (MAP) research seldom considered. Traditionally only MAP with high concentrations of magnetic filler (typically between 10 and 90 wt%) have been investigated. This article deals with a hitherto neglected aspect of research, namely MAP containing lower magnetic filler concentrations (1 to 3 wt%). This article utilizes a range of spectroscopic analysis methods (Raman and FTIR) and their applicability to MAP characterization at wavelengths ranging from 2.5 to 25 mu m. Particular attention is paid to low carbonyl iron particle (CIP) concentrations in MAP for which the emergence of capillary doublets at a critical 2 wt% concentration is revealed. This results in measurable magnetic field-dependent changes in IR absorption at a wavelength of 4.255 mu m together with a detectable CO2 susceptibility. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48366. KW - ELASTOMERS KW - magnetism and magnetic properties KW - sensors and actuators KW - spectroscopy Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-25913 SN - 1097-4628 N1 - Corresponding author: Nina Prem VL - 137 IS - 7 SP - 1 EP - 7 PB - Wiley ER - TY - JOUR A1 - Prem, Nina A1 - Sindersberger, Dirk A1 - Striegl, Birgit A1 - Böhm, Valter A1 - Monkman, Gareth J. T1 - Shape memory effects using magnetoactive Boron-organo-silicon oxide polymers JF - Macromolecular Chemistry and Physics N2 - Thermomechanical shape memory materials have certain disadvantages when it comes to 3D volumetric reproduction intended for rapid prototyping or robotic prehension. The need to constantly supply energy to counteract elastic retraction forces in order to maintain the required geometry, together with the inability to achieve conformal stability at elevated temperatures, limits the application of thermal shape memory polymers. Form removal also presents problems as most viscoelastic materials do not ensure demolding stability. This work demonstrates how magnetoactive boron−organo−silicon oxide polymers under the influence of an applied magnetic field can be used to achieve energy free sustainable volumetric shape memory effects over extended periods. The rheopectic properties of boron−organo−silicon oxide materials sustain form removal without mold distortion. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-23205 N1 - Corresponding Author: Gareth J. Monkman VL - 221 IS - 15 SP - 1 EP - 8 PB - Wiley ER - TY - JOUR A1 - Maier, Robert A1 - Schlattl, Andreas A1 - Guess, Thomas A1 - Mottok, Jürgen T1 - CausalOps - Towards an industrial lifecycle for causal probabilistic graphical models JF - Information and Software Technology N2 - Context: Causal probabilistic graph-based models have gained widespread utility, enabling the modeling of cause-and-effect relationships across diverse domains. With their rising adoption in new areas, such as safety analysis of complex systems, software engineering, and machine learning, the need for an integrated lifecycle framework akin to DevOps and MLOps has emerged. Currently, such a reference for organizations interested in employing causal engineering is missing. This lack of guidance hinders the incorporation and maturation of causal methods in the context of real-life applications. Objective: This work contextualizes causal model usage across different stages and stakeholders and outlines a holistic view of creating and maintaining them within the process landscape of an organization. Method: A novel lifecycle framework for causal model development and application called CausalOps is proposed. By defining key entities, dependencies, and intermediate artifacts generated during causal engineering, a consistent vocabulary and workflow model to guide organizations in adopting causal methods are established. Results: Based on the early adoption of the discussed methodology to a real-life problem within the automotive domain, an experience report underlining the practicability and challenges of the proposed approach is discussed. Conclusion: It is concluded that besides current technical advancements in various aspects of causal engineering, an overarching lifecycle framework that integrates these methods into organizational practices is missing. Although diverse skills from adjacent disciplines are widely available, guidance on how to transfer these assets into causality-driven practices still need to be addressed in the published literature. CausalOps’ aim is to set a baseline for the adoption of causal methods in practical applications within interested organizations and the causality community. KW - Causal engineering KW - Model lifecycle KW - MLOps KW - Causal graphical models Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-73350 SN - 0950-5849 N1 - Corresponding author der OTH Regensburg: Robert Maier PB - Elsevier ER - TY - JOUR A1 - Grabinger, Lisa A1 - Hauser, Florian A1 - Mottok, Jürgen T1 - On the perception of graph layouts JF - Journal of Software: Evolution and Process N2 - In the field of software engineering, graph-based models are used for a variety of applications. Usually, the layout of those graphs is determined at the discretion of the user. This article empirically investigates whether different layouts affect the comprehensibility or popularity of a graph and whether one can predict the perception of certain aspects in the graph using basic graphical laws from psychology (i.e., Gestalt principles). Data on three distinct layouts of one causal graph is collected from 29 subjects using eye tracking and a print questionnaire. The evaluation of the collected data suggests that the layout of a graph does matter and that the Gestalt principles are a valuable tool for assessing partial aspects of a layout. KW - causal graphs KW - eye tracking KW - gestalt principles KW - graph layouts KW - modeling languages Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-62973 N1 - Corresponding author: Lisa Grabinger PB - Wiley ER - TY - JOUR A1 - Kriegl, Raphael A1 - Krenkel, Lars A1 - Shamonin (Chamonine), Mikhail T1 - Preservation of wetting ridges using field-induced plasticity of magnetoactive elastomers JF - Journal of Colloid and Interface Science N2 - Hypothesis. The presence of a wetting ridge is crucial for many wetting phenomena on soft substrates. Conventional experimental observations of a wetting ridge require permanent presence of a droplet. The magnetic field-induced plasticity effect (FIPE) of soft magnetoative elastomers (MAEs) allows one to overcome this limitation. Depositing a droplet onto an MAE surface and applying a magnetic field fixes the wetting ridge in place due to the FIPE. The droplet can be removed to investigate the ridge with ease using conventional optical methods. Experiments. The wetting ridge is observed on MAEs with different shear moduli and different material thicknesses by confocal laser scanning microscopy (LSM). The preservation quality of the ridge is analyzed for several values of magnetic field from 10 mT to 270 mT. To verify the plausibilty of results obtained, the measured shape is compared to a theoretical model by Style & Dufresne. Findings. Upon removal of the sessile droplet, the deformation remains embossed onto the MAE surface as long as the magnetic field remains applied. The height of the ridge peak on soft samples (effective shear modulus kPa) is close to the theoretical prediction for a magnetic flux density of 50 mT. The magnitude of the external magnetic field magnifies the height of the wetting ridge. KW - Wetting ridge KW - Droplet KW - Magnetoactive elastomer KW - Magnetorheological elastomer KW - Field-induced plasticity KW - Confocal laser scanning microscopy Y1 - 2025 U6 - https://doi.org/10.1016/j.jcis.2024.12.132 SN - 0021-9797 N1 - Corresponding author der OTH Regensburg: Raphael Kriegl VL - 683 SP - 1019 EP - 1027 PB - Elsevier ER - TY - JOUR A1 - Mühlbauer, Andreas A1 - Keiner, Dominik A1 - Gerhards, Christoph A1 - Caldera, Upeksha A1 - Sterner, Michael A1 - Breyer, Christian T1 - Assessment of technologies and economics for carbon dioxide removal from a portfolio perspective JF - International Journal of Greenhouse Gas Control N2 - Carbon dioxide removal (CDR) is essential to achieve ambitious climate goals limiting global warming to less than 1.5◦C, and likely for achieving the 1.5◦C target. This study addresses the need for diverse CDR portfolios and introduces the LUT-CDR tool, which assesses CDR technology portfolios aligned with hypothetical societal preferences. Six scenarios are described, considering global deployment limitations, techno-economic factors, area requirements, technology readiness, and storage security for various CDR options. The results suggest the feasibility of large-scale CDR, potentially removing 500–1750 GtCO2 by 2100 to meet the set climate targets. For a 1.0◦C climate goal, CDR portfolios necessitate 12.0–37.5% more primary energy compared to a scenario without CDR. Remarkably, funding a 1.0◦C target requires only 0.42–0.65% of the projected global gross domestic product. Bioenergy carbon capture and sequestration and rainfall-based afforestation play limited roles, while secure sequestration of captured CO2 via direct air capture, electricity-based carbon sequestration, and desalination-based afforestation emerge as more promising options. The study offers crucial techno-economic parameters for implementing CDR options in future energy-industry-CDR system analyses and demonstrates the tool’s flexibility through alternative assumptions. It also discusses limitations, sensitivities, potential tradeoffs, and outlines options for future research in the area of large-scale CDR. Y1 - 2025 U6 - https://doi.org/10.1016/j.ijggc.2024.104297 VL - 141 PB - Elsevier ER - TY - JOUR A1 - Monkman, Gareth J. A1 - Sindersberger, Dirk A1 - Prem, Nina A1 - Diermeier, Andreas A1 - Szecsey, Tamara T1 - Dielectric behaviour of magnetic hybrid materials JF - Physical Sciences Reviews N2 - The objectives of this work include the analysis of electrical and magnetic properties of magneto-elastic hybrid materials with the intention of developing new techniques for sensor and actuator applications. This includes the investigation of dielectric properties at both low and high frequencies. The behaviour of capacitors whose dielectrics comprise magnetic hybrid materials is well known. Such interfacial magnetocapacitance can be varied according to magnetic content, magnetic flux density and the relative permittivity of the polymer matrix together with other dielectric content. The basic function of trapping electrical charges in polymers (electrets) is also established technology. However, the combination of magnetoactive polymers and electrets has led to the first electromagnetic device capable of adhering to almost any material, whether magnetically susceptible or not. During the course of this research, in addition to dielectrics, electrically conductive polymers based on (PDMS) matrices were developed in order to vary the electrical properties of the material in a targeted manner. In order to ensure repeatable results, this demanded new fabrication techniques hitherto unavailable. The 3D printing of silicones is far from being a mature technology and much pioneering work was necessary before extending the usual 3 d.o.f. to include orientation about and diffusion of particles in these three axes, thus leading to the concept of 6D printing. In 6D printing, the application of a magnetic field can be used during the curing process to control the particulate distribution and thus the spatial filler particle density as desired. Most of the devices (sensors and actuators) produced by such methods contain levels of carbonyl iron powder (CIP) embedded magnetic filler of up to 70 wt%. Contrary to this, a hitherto neglected research area, namely magnetoactive polymers (MAPs) having significantly lower magnetic particle concentrations (1 to 3 wt% CIP) were also investigated. With filler concentrations lower than 3 wt%, structures are formed which are completely absent at higher filler levels. CIP concentrations in the range of 1wt% demonstrate the formation of toroidal structures. Further development of coherent rings with a compact order results as filler concentrations increase towards 2 wt%. Above 3 wt% the structure eventually disintegrates to the usual random order found in traditional MAP with higher CIP content. Structured samples containing 1%–3 wt% CIP were investigated with the aid of X-ray tomography where solitary ring structures can be observed and eventually the formation of capillary doubles. Over wavelengths ranging from 1 to 25 µm, spectroscopic analysis of thin film MAP samples containing 2 wt% CIP revealed measurable magnetic-field-dependent changes in IR absorption at a wavenumber 2350 (λ = 4.255 µm). This was found to be due to the diamagnetic susceptibility of atmospheric carbon dioxide (CO2). Consequently, the first potential application for sparse matrix MAPs was found. KW - cappillary doublet KW - diamagnetic KW - elastomer dielectric KW - FTIR KW - interfacial magnetocapacitance KW - magnetoactive polymer KW - PDMS KW - toroid Y1 - 2021 U6 - https://doi.org/10.1515/psr-2019-0121 N1 - Corresponding author: Gareth J. Monkman VL - 7 IS - 10 SP - 1169 EP - 1185 PB - de Gruyter ER - TY - JOUR A1 - Schmidt, Henrik A1 - Straub, Benedikt B. A1 - Sindersberger, Dirk A1 - Bröckel, Ulrich A1 - Monkman, Gareth J. A1 - Auernhammer, Günter T1 - Collision and separation of nickel particles embedded in a Poly dimethylsiloxan matrix under a rotating magnetic field: A strong magneto active function JF - Colloid and Polymer Science N2 - In order to function as soft actuators, depending on their field of use, magnetorheological elastomers (MREs) must fulfill certain criteria. To name just a few, these can include rapid response to external magnetic fields, mechanical durability, mechanical strength, and/or large deformation. Of particular interest are MREs which produce macroscopic deformation for small external magnetic field variations. This work demonstrates how this can be achieved by just a small change in magnetic field orientation. To achieve this, (super)paramagnetic nickel particles of size ≈ 160 μm were embedded in a non-magnetic polydimethylsiloxan (PDMS) (661–1301 Pa) and their displacement in a stepwise rotated magnetic field (170 mT) recorded using a video microscope. Changes in particle aggregation resulting from very small variations in magnetic field orientation led to the observation of a new strongly magneto-active effect. This configuration is characterized by an interparticle distance in relation to the angle difference between magnetic field and particle axis. This causes a strong matrix deformation which in turn demonstrates hysteresis on relaxation. It is shown that the occurrence strongly depends on the particle size, particle distance, and stiffness of the matrix. Choosing the correct parameter combination, the state can be suppressed and the particle-matrix system demonstrates no displacement or hysteresis. In addition, evidences of non-negligible higher order magnetization effects are experimentally ascertained which is qualitatively in agreement with similar, already theoretically described, particle systems. Even at larger particle geometries, the new strongly magneto-active configuration is preserved and could create macroscopic deformation changes. Y1 - 2021 U6 - https://doi.org/10.1007/s00396-020-04784-4 VL - 299 SP - 955 EP - 967 PB - Springer ER - TY - JOUR A1 - Kinoshita, Keisuke A1 - Delcroix, Marc A1 - Gannot, Sharon A1 - Habets, Emanuel A. P. A1 - Haeb-Umbach, Reinhold A1 - Kellermann, Walter A1 - Leutnant, Volker A1 - Maas, Roland A1 - Nakatani, Tomohiro A1 - Raj, Bhiksha A1 - Sehr, Armin A1 - Yoshioka, Takuya T1 - A summary of the REVERB challenge: state-of-the-art and remaining challenges in reverberant speech processing research JF - Eurasip journal on advances in signal processing N2 - In recent years, substantial progress has been made in the field of reverberant speech signal processing, including both single- and multichannel dereverberation techniques and automatic speech recognition (ASR) techniques that are robust to reverberation. In this paper, we describe the REVERB challenge, which is an evaluation campaign that was designed to evaluate such speech enhancement (SE) and ASR techniques to reveal the state-of-the-art techniques and obtain new insights regarding potential future research directions. Even though most existing benchmark tasks and challenges for distant speech processing focus on the noise robustness issue and sometimes only on a single- channel scenario, a particular novelty of the REVERB challenge is that it is carefully designed to test robustness against reverberation, based on both real, single- channel, and multichannel recordings. This challenge attracted 27 papers, which represent 25 systems specifically designed for SE purposes and 49 systems specifically designed for ASR purposes. This paper describes the problems dealt within the challenge, provides an overview of the submitted systems, and scrutinizes them to clarify what current processing strategies appear effective in reverberant speech processing. KW - Automatic speech recognition KW - Dereverberation KW - Evaluation campaign KW - QUALITY KW - REVERB challenge KW - Reverberation Y1 - 2016 U6 - https://doi.org/10.1186/s13634-016-0306-6 VL - 2016 PB - Springer Nature ER - TY - JOUR A1 - Sterner, Michael A1 - Bauer, Franz T1 - Power-to-X im Kontext der Energiewende und des Klimaschutzes in Deutschland JF - Chemie-Ingenieur-Technik N2 - Um den Einfluss verschiedener Power-to-X-Verfahren auf die Transformation des deutschen Energiesystems und das Erreichen der Klimaschutzziele zu überprüfen, wurde ein sektorübergreifendes Energiesystemmodel entwickelt. Die daraus gewonnenen Ergebnisse zeigen: Für eine erfolgreiche Energiewende ist der Einsatz von Power-to-X in Zukunft unverzichtbar. Vor allem in Bereichen und Sektoren, in denen hohe Energiedichten erforderlich und nur wenig andere Optionen zur Defossilisierung vorhanden sind, werden Power-to-X-Technologien zwingend notwendig. T2 - Power-to-X in Context of Energy Transition and Climate Change Mitigation in Germany KW - Power-to-Gas KW - Climate mitigation KW - Energy system KW - Modeling KW - Power-to-X KW - Klimaschutz KW - Energiewende Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-11669 SN - 0009-286X N1 - Corresponding author: Franz Bauer VL - 92 IS - 1-2 SP - 85 EP - 90 PB - Wiley ER - TY - JOUR A1 - Keiner, Dominik A1 - Walter, Lukas A1 - Bogdanov, Dmitrii A1 - Peters, Ian Marius A1 - Breyer, Christian T1 - Assessing the impact of bifacial solar photovoltaics on future power systems based on capacity-density-optimised power plant yield modelling JF - Solar Energy N2 - Bifacial solar photovoltaic (PV) technology is currently taking over the solar PV module market, exceeding a 90% share in 2025. This important technology must be included in energy system modelling. This study provides a method for calculating the yield of monofacial and bifacial power plants in fixed-tilted, single-axis tracking, and east-west facing vertical setup. A novel method is introduced to maximise the capacity density of solar PV power plants without the need for detailed land cost for the most efficient use of the occupied area. The results indicate a 15-20% yield gain from single-axis tracking compared to fixed-tilted power plants, and a limited bifacial gain of up to 10% for most areas of the world. Higher bifacial gains are sporadically possible in specific conditions. Fixed-tilted systems show higher bifacial gains. Optimising tilt angles and row pitch would allow for 147 MW/ km2 capacity density today, though on average 70-110 MW/km2 can be achieved for 20.2% module efficiency. The impact on the power system, studied in a free cost optimisation scenario and forcing vertical bifacial PV scenario, implying agrivoltaics, is not significant with a +/- 10% change in total solar PV capacity, change in installed wind power of on average-10%, increase of installed battery capacity of on average 5%, and an on average changed levelised cost of electricity of-2% globally. Bifacial solar PV technology has been found to be beneficial but no game changer for future power systems; system improvements are widely possible underlining the important role of this technology. KW - Bifacial KW - Capacity density KW - Energy system modelling KW - Monofacial KW - photovoltaics KW - Power plant Y1 - 2025 U6 - https://doi.org/10.1016/j.solener.2025.113543 VL - 295 PB - Elsevier ER - TY - JOUR A1 - Doepfert, Markus A1 - Candas, Soner A1 - Kraus, Hermann A1 - Tzscheutschler, Peter A1 - Hamacher, Thomas T1 - Assessing the techno-economic benefits of LEMs for different grid topologies and prosumer shares JF - iScience N2 - The shift toward decentralized and renewable energy sources has introduced significant challenges to traditional power systems, necessitating innovative market designs. Local energy markets present a viable solution for integrating distributed energy resources such as photovoltaic systems, electric vehicles, and heat pumps. This study investigates the techno-economic implications of local energy markets compared to conventional market designs, focusing on their impact on average energy prices and operational peak power. Through comprehensive simulations across various grid topologies with varying penetration levels of the distributed energy resources, totaling 400 simulation setups, we demonstrate that local energy markets can enhance economic efficiency and grid stability with 99% of the scenarios boasting lower average energy prices and 80% lower operational peak power levels. The findings suggest that local energy markets can play a role in the future energy system, provided that additional infrastructure, management costs, and bureaucratic complexity are kept to a minimum. Y1 - 2025 U6 - https://doi.org/10.1016/j.isci.2025.112493 VL - 28 IS - 6 PB - Elsevier - Cell Press ER - TY - JOUR A1 - Thema, Martin A1 - Bauer, Franz A1 - Sterner, Michael T1 - Power-to-Gas: Electrolysis and methanation status review JF - Renewable and Sustainable Energy Reviews N2 - This review gives a worldwide overview on Power-to-Gas projects producing hydrogen or renewable substitute natural gas focusing projects in central Europe. It deepens and completes the content of previous reviews by including hitherto unreviewed projects and by combining project names with details such as plant location. It is based on data from 153 completed, recent and planned projects since 1988 which were evaluated with regards to plant allocation, installed power development, plant size, shares and amounts of hydrogen or substitute natural gas producing examinations and product utilization phases. Cost development for electrolysis and carbon dioxide methanation was analyzed and a projection until 2030 is given with an outlook to 2050. The results show substantial cost reductions for electrolysis as well as for methanation during the recent years and a further price decline to less than 500 euro per kilowatt electric power input for both technologies until 2050 is estimated if cost projection follows the current trend. Most of the projects examined are located in Germany, Denmark, the United States of America and Canada. Following an exponential global trend to increase installed power, today's Power-to-Gas applications are operated at about 39 megawatt. Hydrogen and substitute natural gas were investigated on equal terms concerning the number of projects. KW - Biological CO2-Methanation KW - Chemical CO2-Methanation KW - Cost-development KW - Electrolysis KW - Power-to-Gas Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-26238 N1 - Corresponding author: Martin Thema VL - 112 IS - 7 SP - 775 EP - 787 PB - Elsevier ER - TY - JOUR A1 - Sterner, Michael A1 - Hofrichter, Andreas A1 - Meisinger, Alexander A1 - Bauer, Franz A1 - Pinkwart, Karsten A1 - Maletzko, Annabelle A1 - Dittmar, Felix A1 - Cremers, Carsten T1 - 19 Import options for green hydrogen and derivatives - An overview of efficiencies and technology readiness levels JF - International Journal of Hydrogen Energy N2 - The import of hydrogen and derivatives forms part of many national strategies and is fundamental to achieving climate protection targets. This paper provides an overview and technical comparison of import pathways for hydrogen and derivatives in terms of efficiency, technological maturity and development and construction times with a focus on the period up to 2030. The import of hydrogen via pipeline has the highest system efficiency at 57-67 % and the highest technological maturity with a technology readiness level (TRL) of 8-9. The import of ammonia and methanol via ship and of SNG via pipeline shows efficiencies in the range of 39-64 % and a technological maturity of TRL 7 to 9 when using point sources. Liquid hydrogen, LOHC and Fischer-Tropsch products have the lowest efficiency and TRL in comparison. The use of direct air capture (DAC) reduces efficiency and TRL considerably. Reconversion of the derivatives to hydrogen is also associated with high losses and is not achievable for all technologies on an industrial scale up to 2030. In the short to medium term, import routes for derivatives that can utilise existing infrastructures and mature technologies are the most promising for imports. In the long term, the most promising option is hydrogen via pipelines. KW - Hydrogen KW - Derivatives KW - Power-to-X KW - Efficiency KW - TRL KW - Construction time KW - Technical assessment KW - Import KW - Hydrogen strategy KW - Energy system modelling Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-77756 SN - 0360-3199 N1 - Corresponding author der OTH Regensburg: Michael Sterner VL - 90 SP - 1112 EP - 1127 PB - Elsevier ER - TY - JOUR A1 - Kovalev, Alexander A1 - Belyaeva, Inna A. A1 - von Hofen, Christian A1 - Gorb, Stanislav A1 - Shamonin (Chamonine), Mikhail T1 - Magnetically Switchable Adhesion and Friction of Soft Magnetoactive Elastomers JF - Advanced Engineering Materials N2 - Herein, the effect of an applied moderate (~240 mT) magnetic field on the work of adhesion (WoA) of mechanically soft (the shear modulus ~10 kPa) magnetoactive elastomer (MAE) samples with two different mass fractions (70 and 80 wt%) of carbonyl iron powder (CIP) is concerned. The unfilled elastomer sample is used for comparison. Due to some sedimentation of filling particles, the concentration of inclusions in thin (~10 μm) subsurface layers is different. It is shown that the WoA increases (up to 1.8-fold) on the particle-enriched side (PES) in the magnetic field and its value is higher for higher filler concentration. On the particle-depleted side (PDS), WoA does not depend on particle concentration and on the magnetic field. Adhesion and friction are coupled in MAEs. No statistically significant difference in the friction coefficient, determined from the extended Amontons´ law, depending on sample side, CIP concentration, or presence of magnetic field is found. However, the PDS in the magnetic field demonstrates significantly higher critical shear stress compared to that for the PES or PDS in the absence of magnetic field. Correlations between different surface properties are discussed. Obtained results are useful for the development of magnetically controllable soft robots. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-45283 N1 - Corresponding authors: Stanislav Gorb und Mikhail Shamonin VL - 24 IS - 10 SP - 1 EP - 8 PB - WILEY-VCH ER - TY - JOUR A1 - Kravanja, Gaia A1 - Kriegl, Raphael A1 - Hribar, Luka A1 - Glavan, Gašper A1 - Drevenšek‐Olenik, Irena A1 - Shamonin (Chamonine), Mikhail A1 - Jezeršek, Matija T1 - Magnetically Actuated Surface Microstructures for Efficient Transport and Tunable Separation of Droplets and Solids JF - Advanced Engineering Materials N2 - Efficient transportation of droplets (∽10 ¹ ̶̶̶̶ 10 ² µl) and small solid objects (∽10 ¹ ̶ 10 ² mm ³ ) have important applications in many fields, such as microfluidics, lab‐on‐a‐chip devices, drug delivery, etc. A novel multifunctional surface consisting of a periodic array of micro‐lamellae from a soft magnetoactive elastomer (MAE) on a plastic substrate is reported for these purposes. The physical origin of the propulsion is the bending of soft magnetic lamellae in non‐uniform magnetic fields, which is also observed in uniform magnetic fields. The magnetoactive surface is fabricated using a facile and rapid method of laser ablation. The propulsion of items is realized using a four‐pole rotating magnet. This results in a cyclic lamellar fringe motion over the micro‐structured surface and brings an advantage of easy reciprocation of transport by rotation reversal. Two modes of object transportation are identified: “pushing” mode for precise control of droplet and solid positioning and “bouncing” mode for heavier solid objects transportation. A water droplet of 5 μl or a glass sphere with a 2.1 mm diameter can be moved at a maximum speed of 60 mm s ⁻¹ . The multifunctionality of the proposed mechatronic platform is demonstrated on the examples of selective solid‐liquid separation and droplet merging. KW - Keywordslaser micromachinings KW - magnetoactive elastomers KW - magnetoresponsivesurfaces KW - object separations KW - object transportations Y1 - 2023 U6 - https://doi.org/10.1002/adem.202301000 SN - 1527-2648 VL - 25 IS - 22 SP - 1 EP - 11 PB - Wiley-VCH ER - TY - JOUR A1 - Kravanja, Gaia A1 - Belyaeva, Inna A. A1 - Hribar, Luka A1 - Drevenšek‐Olenik, Irena A1 - Shamonin (Chamonine), Mikhail A1 - Jezeršek, Matija T1 - Laser Micromachining of Magnetoactive Elastomers as Enabling Technology for Magnetoresponsive Surfaces JF - Advanced Materials Technologies N2 - A simple method for structuring of the surface of a magnetoactive elastomer (MAE) on the tens of micrometers scale, which capabilities extend beyond conventional mold-based polymer casting, is reported. The method relies on the ablation of the material by absorption of nanosecond infrared pulses from a commercial laser. It is shown that it is possible to fabricate parallel lamellar structures with a high aspect ratio (up to 6:1) as well as structures with complex scanning trajectories. The method is fast (fabrication time for the 7 × 7 mm2 is about 60 s), and the results are highly reproducible. To illustrate the capabilities of the fabrication method, both orthogonal to the MAE surface and tilted lamellar structures are fabricated. These magnetosensitive lamellae can be easily bent by ±45° using an external magnetic field of about 230 mT. It is demonstrated that this bending allows one to control the sliding angle of water droplets in a great range between a sticky (>90°) and a sliding state (<20°). Perspectives on employing this fabrication technology for magnetosensitive smart surfaces in microfluidic devices and soft robotics are discussed. Y1 - 2021 U6 - https://doi.org/10.1002/admt.202101045 VL - 7 IS - 5 SP - 1 EP - 8 PB - Wiley ER - TY - JOUR A1 - Kravanja, Gaia A1 - Belyaeva, Inna A. A1 - Hribar, Luka A1 - Drevenšek‐Olenik, Irena A1 - Jezeršek, Matija A1 - Shamonin (Chamonine), Mikhail T1 - Tunable Drop Splashing on Magnetoactive Elastomers JF - Advanced Materials Interfaces N2 - The significant effect of an external dc magnetic field on the splashing behavior of ethanol drops impacting on the unstructured (flat) surface of soft magnetoactive elastomers (MAEs) is reported. The Weber number corresponding to the transition between the deposition and the splashing regime is reduced by ≈20% in a moderate magnetic field of ≈300 mT. Alongside this effect, a two-fold increase of the initial deceleration of the ejection sheet is observed for the softest sample. The main underlying mechanism for the observed phenomena is believed to be the magnetic-field-induced stiffening of the MAEs. Further possible mechanisms are magnetically induced changes in the surface roughness and magnetic-field-induced plasticity (magnetic shape memory effect). The potential application areas are magnetically regulable wetting and magneto-responsive surfaces for controlling the drop splashing. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-24504 N1 - Corresponding author: Mikhail Shamonin VL - 8 IS - 11 SP - 1 EP - 7 PB - Wiley ER - TY - GEN A1 - Kriegl, Raphael A1 - Kravanja, Gaia A1 - Hribar, Luka A1 - Jezeršek, Matija A1 - Drevenšek‐Olenik, Irena A1 - Shamonin (Chamonine), Mikhail T1 - Characterization of Wetting Properties of Magnetoactive Elastomer Surfaces T2 - Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS) - 2023, September 11–13, 2023 Austin, Texas, USA N2 - Commercially available contact angle (CA) measuring devices usually do not allow for the application of magnetic fields to the sample under test. A setup for measuring the CA of liquids on magnetosensitive surfaces has been developed specifically for investigating the surfaces of magnetoactive elastomers (MAEs). The addition of a programmable linear stage, which moves a permanent magnet, allows for fine control of the magnetic field applied to the MAE without the need for large and power-consuming electromagnets. Paired with a custom control and evaluation software, this measurement setup operates semiautomatically, limiting operator error and increasing precision, speed, as well as repeatability of static and dynamic CA measurements for different magnetoactive materials. The software is equipped with robust droplet fitting algorithms to avoid experimental challenges arising with soft magnetoactive materials, such as the curling of sample edges or diffuse non-reflective surfaces. Several application examples on MAE surfaces, both processed and unprocessed, are presented. KW - magnetoactive elastomers KW - image processing KW - droplet contour fitting KW - contact angle Y1 - 2023 SN - 978-0-7918-8752-3 U6 - https://doi.org/10.1115/SMASIS2023-110998 N1 - Corresponding author: Raphael Kriegl PB - The American Society of Mechanical Engineers CY - New York, USA ER -