@article{Diamantidis, author = {Diamantidis, Dimitris}, title = {A Critical View on Environmental and Human Risk Acceptance Criteria}, series = {International Journal of Environmental Science and Development}, volume = {8}, journal = {International Journal of Environmental Science and Development}, number = {1}, doi = {10.18178/ijesd.2017.8.1.921}, pages = {62 -- 66}, abstract = {Natural and technological hazards have a major impact on environmental and human safety. Risk assessment plays an essential role in the risk management of the effects of such hazards. This contribution summarizes first the general formulation of risk depending on two parameters: hazard probability and associated consequences. Problems faced in industrial applications based on the experience of the author are discussed. Risk acceptance criteria for the contributors to risk i.e. human, economic and environment are critically reviewed. Resilience based criteria are also included and conclusions for future developments are provided.}, language = {en} } @article{FranzWolfPeriyasamyetal., author = {Franz, Maja and Wolf, Lucas and Periyasamy, Maniraman and Ufrecht, Christian and Scherer, Daniel D. and Plinge, Axel and Mutschler, Christopher and Mauerer, Wolfgang}, title = {Uncovering Instabilities in Variational-Quantum Deep Q-Networks}, series = {Journal of the Franklin Institute}, journal = {Journal of the Franklin Institute}, edition = {In Press, Corrected Proof}, publisher = {Elsevier}, issn = {0016-0032}, doi = {10.1016/j.jfranklin.2022.08.021}, abstract = {Deep Reinforcement Learning (RL) has considerably advanced over the past decade. At the same time, state-of-the-art RL algorithms require a large computational budget in terms of training time to converge. Recent work has started to approach this problem through the lens of quantum computing, which promises theoretical speed-ups for several traditionally hard tasks. In this work, we examine a class of hybrid quantumclassical RL algorithms that we collectively refer to as variational quantum deep Q-networks (VQ-DQN). We show that VQ-DQN approaches are subject to instabilities that cause the learned policy to diverge, study the extent to which this afflicts reproduciblity of established results based on classical simulation, and perform systematic experiments to identify potential explanations for the observed instabilities. Additionally, and in contrast to most existing work on quantum reinforcement learning, we execute RL algorithms on an actual quantum processing unit (an IBM Quantum Device) and investigate differences in behaviour between simulated and physical quantum systems that suffer from implementation deficiencies. Our experiments show that, contrary to opposite claims in the literature, it cannot be conclusively decided if known quantum approaches, even if simulated without physical imperfections, can provide an advantage as compared to classical approaches. Finally, we provide a robust, universal and well-tested implementation of VQ-DQN as a reproducible testbed for future experiments.}, language = {en} } @article{SchloplocherEttengruberSteffens, author = {Schloplocher, Paul Dragos and Ettengruber, Stefan and Steffens, Oliver}, title = {Improvements for building-performance simulations by a comparative finite-element method analysis}, series = {Energy and Buildings}, volume = {278}, journal = {Energy and Buildings}, publisher = {Elsevier}, doi = {10.1016/j.enbuild.2022.112563}, pages = {1 -- 12}, abstract = {This paper presents a method to improve building-performance simulations (BPS) by the comparison and analysis of different approaches based on finite-element method (FEM) models. The lumped parameter method (LPM) is used in several BPS programs and tools. It has the advantage of fast computing times and comparably good accuracy for thermal and energy loads. With the help of detailed FEM simulations, it is possible to further improve the degree of detail and accuracy while maintaining the high simulation speed. In this work, we compare time-dependent results for local temperatures in a generic reference room within a given periode of time. In a second step, the differences between the models with respect to various physical effects are analyzed and used to introduce additional equations into the LPM model in order to improve its accuracy. Thus, we discuss potentials for improvement for BPS and demonstrate a method of a practical implementation. The results show minor differences of less than 0.1 K for radiation and heat transfer, so their level of detail in BPS is appropriate. In these terms, no improvements were pursued within the work. However, the FEM simulation is capable of calculating the internal convective heat transfer and thermal bridges more accurately due to the use of computational fluid dynamics (CFD) and the geometrically precise representation of the FEM model. Here, deviations of up to 1 K in room temperature (convective heat transfer) and up to 0.5 K in wall temperatures (thermal bridges) were pointed out. By improving the LPM with equations obtained from the FEM, these deviations can be reduced to less than 0.2 K, which is a considerable improvement in accuracy.}, language = {en} } @article{MaiwaldRoiderSchmidtetal., author = {Maiwald, Frederik and Roider, Clemens and Schmidt, Michael and Hierl, Stefan}, title = {Optical Coherence Tomography for 3D Weld Seam Localization in Absorber-Free Laser Transmission Welding}, series = {Applied Sciences}, volume = {12}, journal = {Applied Sciences}, number = {5}, publisher = {MPDI}, address = {Basel}, doi = {10.3390/app12052718}, pages = {1 -- 11}, abstract = {Quality and reliability are of the utmost importance for manufacturing in the optical and medical industries. Absorber-free laser transmission welding enables the precise joining of identical polymers without additives or adhesives and is well-suited to meet the demands of the aforementioned industries. To attain sufficient absorption of laser energy without absorbent additives, thulium fiber lasers, which emit in the polymers' intrinsic absorption spectrum, are used. Focusing the laser beam with a high numerical aperture provides significant intensity gradients inside the workpiece and enables selective fusing of the internal joining zone without affecting the surface of the device. Because seam size and position are crucial, the high-quality requirements demand internal weld seam monitoring. In this work, we propose a novel method to determine weld seam location and size using optical coherence tomography. Changes in optical material properties because of melting and re-solidification during welding allow for weld seam differentiation from the injection-molded base material. Automatic processing of the optical coherence tomography data enables the identification and measurement of the weld seam geometry. The results from our technique are consistent with microscopic images of microtome sections and demonstrate that weld seam localization in polyamide 6 is possible with an accuracy better than a tenth of a millimeter.}, language = {en} } @article{KreitmeierChashinFetisovetal., author = {Kreitmeier, Florian and Chashin, Dmitri V. and Fetisov, Yuri K. and Fetisov, Leonid Y. and Schulz, Irene and Monkman, Gareth J. and Shamonin (Chamonine), Mikhail}, title = {Nonlinear Magnetoelectric Response of Planar Ferromagnetic-Piezoelectric Structures to Sub-Millisecond Magnetic Pulses}, series = {Sensors}, volume = {12}, journal = {Sensors}, number = {11}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/s121114821}, pages = {14821 -- 14837}, abstract = {The magnetoelectric response of bi- and symmetric trilayer composite structures to pulsed magnetic fields is experimentally investigated in detail. The structures comprise layers of commercially available piezoelectric (lead zirconate titanate) and magnetostrictive (permendur or nickel) materials. The magnetic-field pulses have the form of a half-wave sine function with duration of 450 µs and amplitudes ranging from 500 Oe to 38 kOe. The time dependence of the resulting voltage is presented and explained by theoretical estimations. Appearance of voltage oscillations with frequencies much larger than the reciprocal pulse length is observed for sufficiently large amplitudes (~1-10 kOe) of the magnetic-field pulse. The origin of these oscillations is the excitation of bending and planar acoustic oscillations in the structures. Dependencies of the magnetoelectric voltage coefficient on the excitation frequency and the applied magnetic field are calculated by digital signal processing and compared with those obtained by the method of harmonic field modulation. The results are of interest for developing magnetoelectric sensors of pulsed magnetic fields as well as for rapid characterization of magnetoelectric composite structures.}, language = {en} } @article{ApelsmeierGleixnerMayeretal., author = {Apelsmeier, Andreas and Gleixner, Ramona and Mayer, Matthias and Shamonin (Chamonine), Mikhail and Schmauss, Bernhard}, title = {Intensity referencing in an extrinsic optical fiber temperature sensor}, series = {Procedia Engineering}, volume = {5}, journal = {Procedia Engineering}, publisher = {Elsevier}, doi = {10.1016/j.proeng.2010.09.301}, pages = {1095 -- 1098}, abstract = {Optical fiber sensors based on intensity measurement require some form of intensity referencing to avoid errors arising from parasitic losses. Known techniques of referencing such as balanced bridge, divided beam systems or two-wavelength referencing are not suitable for low-cost applications since they use relatively complicated optical components such as multiple LED sources, couplers, filters etc. In this work a novel method of referencing in an extrinsic optical fiber sensor system utilizing temperature dependence of absorption edge in a semiconductor crystal is described. The sensor system comprises a single LED source and no optical fiber junctions. The emission spectrum of an LED depends on its temperature. The reference is provided by controlling the temperature of an LED source and transmission measurements with different emission spectra. The entire process is controlled by a microprocessor unit. Performance of a sensor system is investigated and it is shown that the losses in connectors may be compensated for.}, language = {en} } @article{MonkmanSindersbergerPremetal., author = {Monkman, Gareth J. and Sindersberger, Dirk and Prem, Nina and Szecsey, Tamara}, title = {Smart Stiction}, series = {Robotics \& Automation Engineering Journal}, volume = {4}, journal = {Robotics \& Automation Engineering Journal}, number = {4}, publisher = {Juniper Publishers}, doi = {10.19080/RAEJ.2019.04.555641}, abstract = {Soft robotics could loosely be described as the engineering science of expanded dexterity through controllable flexibility. The exploitation of controllable compliance through the judicious choice of soft flexible members, as opposed to a finite number of rigid kinematic joints, can result in greater dexterity without compromising simplicity. One example is the replacement of segmented mechanical legs with simple compliant material eruciform prolegs. To achieve this in robotics, without introducing additional mechanical joints, mobile surfaces with switchable coefficients of friction is essential. This paper explains how, using silicone based smart materials, the rapid alternation between kinematic and static friction (stiction) may be achieved.}, language = {en} } @article{Herrmann, author = {Herrmann, Frank}, title = {Human Experience Versus Rule Decision at Krones AG}, series = {Biomedical Journal of Scientific \& Technical Research}, volume = {42}, journal = {Biomedical Journal of Scientific \& Technical Research}, number = {1}, publisher = {Biomedical Research Network+}, issn = {2574 -1241}, doi = {10.26717/BJSTR.2022.42.006691}, pages = {33255 -- 33260}, abstract = {Final assembly at Krones AG must make the best possible use of its production space and meeting the specified customer due dates is critical. Via a self developed simulation tool, the present scheduling procedure is compared with the one by priority rule shortest slack. As a consequence slack should have a higher importance in the planning}, language = {en} } @article{GoeppelFrikelHaltmeier, author = {G{\"o}ppel, Simon and Frikel, J{\"u}rgen and Haltmeier, Markus}, title = {Data-Proximal Complementary ℓ1-TV Reconstruction for Limited Data Computed Tomography}, series = {Mathematics}, volume = {12}, journal = {Mathematics}, number = {10}, publisher = {MDPI}, issn = {2227-7390}, doi = {10.3390/math12101606}, abstract = {In a number of tomographic applications, data cannot be fully acquired, resulting in severely underdetermined image reconstruction. Conventional methods in such cases lead to reconstructions with significant artifacts. To overcome these artifacts, regularization methods are applied that incorporate additional information. An important example is TV reconstruction, which is known to be efficient in compensating for missing data and reducing reconstruction artifacts. On the other hand, tomographic data are also contaminated by noise, which poses an additional challenge. The use of a single regularizer must therefore account for both the missing data and the noise. A particular regularizer may not be ideal for both tasks. For example, the TV regularizer is a poor choice for noise reduction over multiple scales, in which case ℓ1 curvelet regularization methods are well suited. To address this issue, in this paper, we present a novel variational regularization framework that combines the advantages of different regularizers. The basic idea of our framework is to perform reconstruction in two stages. The first stage is mainly aimed at accurate reconstruction in the presence of noise, and the second stage is aimed at artifact reduction. Both reconstruction stages are connected by a data proximity condition. The proposed method is implemented and tested for limited-view CT using a combined curvelet-TV approach. We define and implement a curvelet transform adapted to the limited-view problem and illustrate the advantages of our approach in numerical experiments.}, language = {en} } @article{MikhaeilGadererDawoud, author = {Mikhaeil, Makram and Gaderer, Matthias and Dawoud, Belal}, title = {On the development of an innovative adsorber plate heat exchanger for adsorption heat transformation processes; an experimental and numerical study}, series = {Energy}, volume = {207}, journal = {Energy}, number = {September}, publisher = {Elsevier}, doi = {10.1016/j.energy.2020.118272}, pages = {1 -- 13}, abstract = {An innovative adsorber plate heat exchanger (APHE), which is developed for application in adsorption heat pumps, chillers and thermal energy storage systems, is introduced. A test frame has been constructed as a representative segment of the introduced APHE for applying loose grains of AQSOA-Z02. Adsorption kinetic measurements have been carried out in a volumetric large-temperature-jump setup under typical operating conditions of adsorption processes. A transient 2-D model is developed for the tested sample inside the setup. The measured temporal uptake variations with time have been fed to the model, through which a micro-pore diffusion coefficient at infinite temperature of 2 E-4 [m2s-1] and an activation energy of 42.1 [kJ mol-1] have been estimated. A 3-D model is developed to simulate the combined heat and mass transfer inside the APHE and implemented in a commercial software. Comparing the obtained results with the literature values for an extruded aluminium adsorber heat exchanger coated with a 500 μm layer of the same adsorbent, the differential water uptake obtained after 300 s of adsorption (8.2 g/100 g) implies a sound enhancement of 310\%. This result proves the great potential of the introduced APHE to remarkably enhance the performance of adsorption heat transformation appliances.}, language = {en} } @article{HuberHeindlSchlosseretal., author = {Huber, Lea and Heindl, Melanie and Schlosser, Marc and Pfitzner, Arno and Dawoud, Belal}, title = {On the Cycle Stability and Macroscopic Structure of Iron Oxide Pellets for Thermochemical Hydrogen Storage: Influence of Water Content during the Pelletizing Process}, series = {Applied Sciences}, volume = {13}, journal = {Applied Sciences}, number = {11}, publisher = {MDPI}, address = {16}, doi = {10.3390/app13116408}, abstract = {Hydrogen storage based on the repeated reduction and oxidation (redox) reactions of iron oxide/iron composites represents a promising technology. This work is dedicated to studying the influence of the amount of water added during the pelletizing process on the cycle stability and structure of iron oxide pellets. The storage composites were prepared from iron oxide (Fe2O3) and 10 wt.-\% support material (cement) with different amounts of water (18 and 33 wt.-\%) in a laboratory-scale pelletizing disk. To evaluate the cycle stability of the composites, the kinetics of the redox reactions were experimentally measured at 800 ∘ C in an atmosphere of 50\% N2 and 50\% H2 (reduction) or 50\% steam (oxidation), respectively. Moreover, the structure of the pellets was analyzed by micro-computed tomography scans. It turned out that pellets with higher water contents attained faster kinetics and a higher cycle stability. The sample with the least water content (18 wt.-\%) needed about 26 min and 19 min to reach a conversion rate of 80\% during the reduction and oxidation reactions of the sixth redox cycle, respectively. In contrast, the sample with the highest water content (33 wt.-\%) could achieve the same conversion rate after 18 min (reduction) and 13 min (oxidation) during the ninth redox cycle.}, language = {en} } @article{Schiek, author = {Schiek, Roland}, title = {Nonlinear refractive index in silica glass}, series = {Optical Materials Expres}, volume = {13}, journal = {Optical Materials Expres}, number = {6}, publisher = {Optica}, doi = {10.1364/ome.489520}, pages = {1727 -- 1740}, abstract = {The third-order nonlinear susceptibility of silica glass is measured via self-phase modulation in standard single mode fibers at a wavelength of 1550 nm. To minimize the influence of polarization state changes along the propagation only meter-long fibers were investigated. With pulse durations of picoseconds a quasi-instantaneous nonlinearity with ultrafast electronic and fast nuclear-vibration contributions produces under conditions of negligible dispersion a classic and clean nonlinear phase shift following exactly the shape of the pulse power. The complex pulse envelope was retrieved from frequency optical gating spectrograms. The nonlinear fiber parameter γ could be determined with an accuracy of 3.7 percent. Considering the mode field structure and the doping influence the nonlinear refractive index of silica glass as the fiber base material was found to be n 2 =2.22⋅10 -16 cm 2 W±6.0\% for picosecond-long pulses. Comparing nonlinear phase shifts from linear and circular polarized light a nuclear-vibration contribution to the cubic fiber nonlinearity of 25 percent was estimated.}, language = {en} } @article{RomanoEhrlich, author = {Romano, Marco and Ehrlich, Ingo}, title = {Classification of damping properties of fabric-reinforced flat beam-like specimens by a degree of ondulation implying a mesomechanic kinematic}, series = {Science and Engineering of Composite Materials}, volume = {31}, journal = {Science and Engineering of Composite Materials}, number = {1}, publisher = {Walter de Gruyter GmbH}, issn = {2191-0359}, doi = {10.1515/secm-2024-0019}, abstract = {In order to determine the influence of the ondulations in fabrics on the damping properties of fiber-reinforced plastics, the structural dynamic properties of fabric- and unidirectionally reinforced plastics are investigated. The free decay behavior of flat beam-like specimens is investigated under fixed-free boundary conditions. As the material damping is consistently higher in fabric-reinforced specimens compared to unidirectionally reinforced ones, a contribution of an additionally acting mesomechanic kinematic in fabric weaves is implied. Based on a degree of ondulation, it is possible to classify the enhancement of the material damping and determine the corresponding energy dissipation. The study provides valuable quantitative relations of the additional damping effect due to the mesomechanic kinematic. Compared to the unidirectionally reinforced material, plain weave enhances the material damping by 37…52\% at ˜OPL=0.0133 , whereas twill weave 2/2 enhances it by 31…40\% at ˜OT2=0.0098 . The consideration of the findings contributes to a deeper understanding of the visco-elastic dynamic behavior of fabric-reinforced plastics and allows further applications in research, development, and industry.}, language = {en} } @article{SteiningerGadererDawoud, author = {Steininger, Peter and Gaderer, Matthias and Dawoud, Belal}, title = {Assessment of the Annual Transmission Heat Loss Reduction of a Refurbished Existing Building with an Advanced Solar Selective Thermal Insulation System}, series = {Sustainability}, volume = {13}, journal = {Sustainability}, number = {13}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/su13137336}, pages = {1 -- 19}, abstract = {A numerical parameter sensitivity analysis of the design parameters of the recently published solar selective thermal insulation system (SATIS) has been carried out to enhance its thermal and optical properties. It turned out that the insulation properties of SATIS can be effectively improved by reducing the length of the glass closure element. Increasing the area share of the light conducting elements (LCEs) and decreasing their length-to-diameter (L/D) ratio were identified as key parameters in order to increase the solar gain. Two SATIS variants were compared with the same wall insulation without SATIS in a yearly energetic performance assessment. The SATIS variant with 10 mm length of the closure element, 44.2\% area share of LCE, as well as front and rear diameters of 12 mm/9 mm shows an 11.8\% lower transmission heat loss over the heating period than the wall insulation without SATIS. A new methodology was developed to enable the implementation of the computed solar gains of SATIS in 1D simulation tools. The result is a radiant heat flow map for integration as a heat source in 1D simulation models. A comparison between the 1D and 3D models of the inside wall heat fluxes showed an integral yearly agreement of 98\%.}, language = {en} } @article{SindersbergerPremMonkman, author = {Sindersberger, Dirk and Prem, Nina and Monkman, Gareth J.}, title = {Structure formation in low concentration magnetoactive polymers}, series = {AIP advances}, volume = {9}, journal = {AIP advances}, number = {3}, publisher = {AIP Publishing}, doi = {10.1063/1.5079997}, abstract = {This paper concerns recent research into the autonomous formation of micro-structures in low carbonyl iron powder (CIP) concentration magneto active polymers (MAP). Higher concentrations of CIP show an isotropic distribution of magnetic filler throughout the entire sample, while autonomous structure formation is possible at mass concentrations lower than 3\%. The formation of micro-toroids commences as CIP concentration approaches 1\% wt. Further development of coherent rings with a defined order follow as CIP concentrations increase toward 2\% wt, whilst exceeding 3\% wt leads to the same isotropic distribution found in higher concentration MAP. Structured samples containing between 1\% wt and 3\% wt CIP were investigated using X-Ray tomography where solitary structures could clearly be observed. The ring structures represent microinductivities whose geometries can be manipulated during fabrication. In addition, these structures are magnetic field sensitive. This is not only relevant to applications in the GHz and THz areas but recent research has revealed implications for optical, thermal, acoustic and even chemical MAP sensors. (C) 2019 Author(s).}, language = {en} } @article{SternerBauer, author = {Sterner, Michael and Bauer, Franz}, title = {Power-to-X im Kontext der Energiewende und des Klimaschutzes in Deutschland}, series = {Chemie-Ingenieur-Technik}, volume = {92}, journal = {Chemie-Ingenieur-Technik}, number = {1-2}, publisher = {Wiley}, issn = {0009-286X}, doi = {10.1002/cite.201900167}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-11669}, pages = {85 -- 90}, abstract = {Um den Einfluss verschiedener Power-to-X-Verfahren auf die Transformation des deutschen Energiesystems und das Erreichen der Klimaschutzziele zu {\"u}berpr{\"u}fen, wurde ein sektor{\"u}bergreifendes Energiesystemmodel entwickelt. Die daraus gewonnenen Ergebnisse zeigen: F{\"u}r 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.}, subject = {Power-to-Gas}, language = {de} } @article{KloiberSchultheissSoteloetal., author = {Kloiber, Jessica and Schultheiß, Ulrich and Sotelo, Lamborghini and Sarau, George and Christiansen, Silke H. and Gavras, Sarkis and Hort, Norbert and Hornberger, Helga}, title = {Corrosion behaviour of electropolished magnesium materials}, series = {Materials Today Communications}, journal = {Materials Today Communications}, edition = {Journal Pre-proof}, publisher = {Elsevier}, doi = {10.1016/j.mtcomm.2023.107983}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-68254}, abstract = {Although magnesium and its alloys are promising candidates as biodegradable implant materials, the tendency for localized corrosion mechanism in physiological environment limit their biomedical application. Electropolishing is an attractive strategy for improving the corrosion behaviour of metals, but it is still largely unexplored in magnesium materials. In this study, the characterization of electropolished surfaces of AM50 and pure magnesium was performed, focussing on their in vitro degradation behaviour in cell medium. Corrosion rates were evaluated using potentiodynamic polarisation. The surface morphology before and after the onset of corrosion was investigated by scanning electron microscopy and confocal laser scanning microscopy. The presented electropolishing process led to improved surface performances, observable by significantly lower corrosion rates (0.08 mm·year-1 in Dulbecco's modified Eagle's medium), lower arithmetical mean height (0.05 µm), lower water contact angle (25-35°) and lower micro hardness (35-50 HV 0.1) compared to mechanically and chemically treated surfaces. MgO/Mg(OH)2 could be detected on electropolished surfaces. The localized corrosion mode could be reduced, but not entirely prevented. Electropolishing shows great potential as post-treatment of magnesium-based components, but detailed tests of the long-term corrosion behaviour are an important area of future research.}, language = {en} } @article{ThemaBauerSterner, author = {Thema, Martin and Bauer, Franz and Sterner, Michael}, title = {Power-to-Gas: Electrolysis and methanation status review}, series = {Renewable and Sustainable Energy Reviews}, volume = {112}, journal = {Renewable and Sustainable Energy Reviews}, number = {7}, publisher = {Elsevier}, doi = {10.1016/j.rser.2019.06.030}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-26238}, pages = {775 -- 787}, abstract = {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.}, language = {en} } @article{SternerHofrichterMeisingeretal., author = {Sterner, Michael and Hofrichter, Andreas and Meisinger, Alexander and Bauer, Franz and Pinkwart, Karsten and Maletzko, Annabelle and Dittmar, Felix and Cremers, Carsten}, title = {19 Import options for green hydrogen and derivatives - An overview of efficiencies and technology readiness levels}, series = {International Journal of Hydrogen Energy}, volume = {90}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.10.045}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77756}, pages = {1112 -- 1127}, abstract = {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.}, language = {en} } @article{KovalevBelyaevavonHofenetal., author = {Kovalev, Alexander and Belyaeva, Inna A. and von Hofen, Christian and Gorb, Stanislav and Shamonin (Chamonine), Mikhail}, title = {Magnetically Switchable Adhesion and Friction of Soft Magnetoactive Elastomers}, series = {Advanced Engineering Materials}, volume = {24}, journal = {Advanced Engineering Materials}, number = {10}, publisher = {WILEY-VCH}, doi = {10.1002/adem.202200372}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-45283}, pages = {1 -- 8}, abstract = {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.}, language = {en} } @article{BartschBehamGebhardtetal., author = {Bartsch, Alexander and Beham, Daniela and Gebhardt, Jakob and Ehrlich, Ingo and Schratzenstaller, Thomas and Monkman, Gareth J.}, title = {Mechanical Properties of NdPrFeB Based Magnetoactive Bisphenol-Free Boron-Silicate Polymers}, series = {Journal of Nanomedicine and Nanotechnology}, volume = {14}, journal = {Journal of Nanomedicine and Nanotechnology}, number = {6}, publisher = {Walsh Medical Media}, issn = {2157-7439}, doi = {10.35248/2157-7439.23.14.705}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-67425}, abstract = {Following a ban on many materials containing bisphenol-A, new bisphenol-free Boron silicates have been found as substitutes. The purpose of this study is to describe the mechanical properties of these bisphenol-free magnetoactive borosilicate polymers containing hard magnetic particles. Samples of 0\%, 33\% and 66\% by wt. were loaded for compression using a universal testing machine. The maximum forces occurring for different travel speeds were compared before and after post-magnetization treatments. The post-magnetization included 2 stages. In addition, the change in mechanical properties within 24 hours after the post-magnetization process was investigated. Furthermore, the influence of speed and particle content were investigated. In general, there is a correlation between the required compressive force and, the level of post-magnetization stress, the increase in travel speed and particle content in the boron silicate. Comparison of the non-post-magnetized and post-magnetized samples using two-tailed t-tests shows that the p-values for all weight fraction changes in NdPrFeB particles and travel speeds are less than 0.001. Also, a comparison between tests in which the traverse speed was varied also showed significant changes in the resulting compression forces. The same is valid for changes in the weight ratio of the NdPrFeB particles in the samples. For post-magnetized samples, no significant difference can be observed in the first 24 hours following magnetization. In summary, the material presents viscoelastic, plastic force-displacement behavior, which can be well recognized by its bi-linear curve shape. The investigation shows that borosilicate polymers based on NdPrFeB can have their mechanical behavior modified and controlled by post-magnetization processes. This opens new possibilities for many future applications.}, language = {en} } @article{GlavanBelyaevaShamoninChamonine, author = {Glavan, Gašper and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail}, title = {On the Piezomagnetism of Magnetoactive Elastomeric Cylinders in Uniform Magnetic Fields: Height Modulation in the Vicinity of an Operating Point by Time-Harmonic Fields}, series = {Polymers}, volume = {16}, journal = {Polymers}, number = {19}, doi = {10.3390/polym16192706}, abstract = {Soft magnetoactive elastomers (MAEs) are currently considered to be promising materials for actuators in soft robotics. Magnetically controlled actuators often operate in the vicinity of a bias point. Their dynamic properties can be characterized by the piezomagnetic strain coefficient, which is a ratio of the time-harmonic strain amplitude to the corresponding magnetic field strength. Herein, the dynamic strain response of a family of MAE cylinders to the time-harmonic (frequency of 0.1-2.5 Hz) magnetic fields of varying amplitude (12.5 kA/m-62.5 kA/m), superimposed on different bias magnetic fields (25-127 kA/m), is systematically investigated for the first time. Strain measurements are based on optical imaging with sub-pixel resolution. It is found that the dynamic strain response of MAEs is considerably different from that in conventional magnetostrictive polymer composites (MPCs), and it cannot be described by the effective piezomagnetic constant from the quasi-static measurements. The obtained maximum values of the piezomagnetic strain coefficient (∼102 nm/A) are one to two orders of magnitude higher than in conventional MPCs, but there is a significant phase lag (35-60°) in the magnetostrictive response with respect to an alternating magnetic field. The experimental dependencies of the characteristics of the alternating strain on the amplitude of the alternating field, bias field, oscillation frequency, and aspect ratio of cylinders are given for several representative examples. It is hypothesized that the main cause of observed peculiarities is the non-linear viscoelasticity of these composite materials.}, language = {en} } @article{GlavanKettlBrunhuberetal., author = {Glavan, Gašper and Kettl, Wolfgang and Brunhuber, Alexander and Shamonin (Chamonine), Mikhail and Drevenšek-Olenik, Irena}, title = {Effect of Material Composition on Tunable Surface Roughness of Magnetoactive Elastomers}, series = {Polymers}, volume = {11}, journal = {Polymers}, number = {4}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/polym11040594}, pages = {1 -- 13}, abstract = {We investigated magnetic-field-induced modifications of the surface roughness of magnetoactive elastomers (MAEs) with four material compositions incorporating two concentrations of ferromagnetic microparticles (70 wt\% and 80 wt\%) and exhibiting two shear storage moduli of the resulting composite material (about 10 kPa and 30 kPa). The analysis was primarily based on spread optical reflection measurements. The surfaces of all four materials were found to be very smooth in the absence of magnetic field (RMS roughness below 50 nm). A maximal field-induced roughness modification (approximately 1 m/T) was observed for the softer material with the lower filler concentration, and a minimal modification (less than 50 nm/T) was observed for the harder material with the higher filler concentration. All four materials showed a significant decrease in the total optical reflectivity with an increasing magnetic field as well. This effect is attributed to the existence of a distinct surface layer that is depleted of microparticles in the absence of a magnetic field but becomes filled with particles in the presence of the field. We analyzed the temporal response of the reflective properties to the switching on and off of the magnetic field and found switching-on response times of around 0.1 s and switching-off response times in the range of 0.3-0.6 s. These observations provide new insight into the magnetic-field-induced surface restructuring of MAEs and may be useful for the development of magnetically reconfigurable elastomeric optical surfaces.}, language = {en} } @article{FoerstlSuessEnglertetal., author = {F{\"o}rstl, Nikolas and S{\"u}ß, Franz and Englert, Carsten and Dendorfer, Sebastian}, title = {Design of a reverse shoulder implant to measure shoulder stiffness during implant component positioning}, series = {Medical Engineering \& Physics}, volume = {121}, journal = {Medical Engineering \& Physics}, edition = {Journal Pre-proof}, publisher = {Elsevier}, doi = {10.1016/j.medengphy.2023.104059}, pages = {22}, abstract = {To avoid dislocation of the shoulder joint after reverse total shoulder arthroplasty, it is important to achieve sufficient shoulder stability when placing the implant components during surgery. One parameter for assessing shoulder stability can be shoulder stiffness. The aim of this research was to develop a temporary reverse shoulder implant prototype that would allow intraoperative measurement of shoulder stiffness while varying the position of the implant components. Joint angle and torque measurement techniques were developed to determine shoulder stiffness. Hall sensors were used to measure the joint angles by converting the magnetic flux densities into angles. The accuracy of the joint angle measurements was tested using a test bench. Torques were determined by using thin-film pressure sensors. Various mechanical mechanisms for variable positioning of the implant components were integrated into the prototype. The results of the joint angle measurements showed measurement errors of less than 5° in a deflection range of ±15° adduction/abduction combined with ±45° flexion/extension. The proposed design provides a first approach for intra-operative assessment of shoulder stiffness. The findings can be used as a technological basis for further developments.}, language = {en} } @article{BartschBurgerGradetal., author = {Bartsch, Alexander and Burger, Moritz and Grad, Marius and Esper, Lukas and Schultheiß, Ulrich and Noster, Ulf and Schratzenstaller, Thomas}, title = {Enhancement of laser cut edge quality of ultra-thin titanium grade 2 sheets by applying an in-process approach using modulated Yb:YAG continuous wave fiber laser}, series = {Discover Mechanical Engineering}, journal = {Discover Mechanical Engineering}, number = {10}, publisher = {Springer}, doi = {10.1007/s44245-023-00018-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-65647}, pages = {9}, abstract = {Titanium is used in many areas due to its excellent mechanical, biological and corrosion-resistant properties. Implants often have thin and filigree structures, providing an ideal application for fine cutting with laser. In the literature, the main focus is primarily on investigating and optimizing the parameters for titanium sheets with thicknesses greater than 1 mm. Hence, in this study, the basic manufacturing parameters of laser power, cutting speed and laser pulse of a 200 W modulated fiber laser are investigated for 0.15 mm thick grade 2 titanium sheets. A reproducible, continuous cut could be achieved using 90 W laser-power and 2 mm/s cutting-speed. Pulse pause variations between 85 and 335 μs in 50 μs steps and a fixed pulse width of 50 μs show that a minimum kerf width of 23.4 μm, as well as a minimum cut edge roughness Rz of 3.59 μm, is achieved at the lowest pulse pause duration. An increase in roughness towards the laser exit side, independent of the laser pulse pause duration, was found and discussed. The results provide initial process parameters for cutting thin titanium sheets and thus provide the basis for further investigations, such as the influence of cutting gas pressure and composition on the cut edge.}, language = {en} } @article{SieglJungbauerGebhardtetal., author = {Siegl, Marco and Jungbauer, Bastian and Gebhardt, Jakob and Judenmann, Anna and Ehrlich, Ingo}, title = {Winding process of fibre-reinforced thermoplastic tubes with integrated tape production through in-situ roving impregnation and infrared consolidation}, series = {The International Journal of Advanced Manufacturing Technology}, volume = {135}, journal = {The International Journal of Advanced Manufacturing Technology}, number = {5-6}, editor = {Baeten, Somayeh}, publisher = {Springer Nature}, doi = {10.1007/s00170-024-14628-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77827}, pages = {2847 -- 2870}, abstract = {This paper introduces a novel method for producing fibre-reinforced thermoplastic tubes by integrating tape production and consolidation into a single operation. This innovation diverges from conventional methods by combining processes to reduce costs by using raw materials instead of organotapes, allowing customised material combinations and utilising residual heat from tape production. The new process uses carbon roving and molten low-viscosity PA6 granulates, processed through a new direct impregnation setup in siphon design. Key advancements include a high-speed impregnation module capable of up to 1 m/s with high-performance extruders, cost-effective infrared emitters for winding, and a powered consolidation unit with adjustable winding angles between ±65° and ±90°. Experiments demonstrate operational speeds of approximately 471 mm/min, with an optimal cross-winding speed of 354 mm/min due to the technical limitations of the laboratory extruder and IR emitter used. Based on the technical limitations of the current system, future improvements and methodological changes will be discussed.}, language = {en} } @article{KravanjaBelyaevaHribaretal., author = {Kravanja, Gaia and Belyaeva, Inna A. and Hribar, Luka and Drevenšek-Olenik, Irena and Jezeršek, Matija and Shamonin (Chamonine), Mikhail}, title = {Tunable Drop Splashing on Magnetoactive Elastomers}, series = {Advanced Materials Interfaces}, volume = {8}, journal = {Advanced Materials Interfaces}, number = {11}, publisher = {Wiley}, doi = {10.1002/admi.202100235}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-24504}, pages = {1 -- 7}, abstract = {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.}, language = {en} } @misc{KrieglKravanjaHribaretal., author = {Kriegl, Raphael and Kravanja, Gaia and Hribar, Luka and Jezeršek, Matija and Drevenšek-Olenik, Irena and Shamonin (Chamonine), Mikhail}, title = {Characterization of Wetting Properties of Magnetoactive Elastomer Surfaces}, series = {Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS) - 2023, September 11-13, 2023 Austin, Texas, USA}, journal = {Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS) - 2023, September 11-13, 2023 Austin, Texas, USA}, publisher = {The American Society of Mechanical Engineers}, address = {New York, USA}, isbn = {978-0-7918-8752-3}, doi = {10.1115/SMASIS2023-110998}, abstract = {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.}, language = {en} } @article{PangerlSukulRuecketal., author = {Pangerl, Jonas and Sukul, Pritam and R{\"u}ck, Thomas and Escher, Lukas and Miekisch, Wolfram and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photoacoustic trace-analysis of breath isoprene and acetone via interband- and Quantum Cascade Lasers}, series = {Sensors and Actuators: B. Chemical}, volume = {424}, journal = {Sensors and Actuators: B. Chemical}, publisher = {Elsevier}, doi = {10.1016/j.snb.2024.136886}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77024}, pages = {12}, abstract = {This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the photoacoustic systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm 1Hz 0.5 and 4.9E-9 Wcm 1Hz 0.5. Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices}, language = {en} } @article{FrankeWagner, author = {Franke, Markus and Wagner, Marcus}, title = {Transient surrogate modeling of modally reduced structures with discontinuous loads and damping}, series = {Archive of Applied Mechanics}, volume = {94}, journal = {Archive of Applied Mechanics}, number = {5}, publisher = {Springer Nature}, doi = {10.1007/s00419-024-02601-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-72834}, pages = {20}, abstract = {In this work, a surrogate model for structural, transient and discontinuously excited finite element method simulations is developed. This allows to reduce the computational effort of repeated calculations of identical models under different load cases. The architecture of the surrogate combines fully connected neural network layers with long short-term memory layers. For the reproduction of different damping ratios, a categorical variable is added to the continuous input data. Based on a recursive flow of the predicted data back to the input layer, long-term dependencies do not vanish due to short-input sequences. The system dimension is reduced by applying the model-order reduction technique for modal decomposition. The high accuracy of the surrogate and the reduction of computational costs are shown on an academic example of a cantilever beam and a real-world example of a robot. The advantages of our approach are illustrated in comparison with state-of-the-art surrogates for transient finite element analysis. By using the surrogate proposed in this study, oscillations due to discontinuous excitation of mechanical structures can be reproduced. For this purpose, only short-input sequences are necessary since the excitation of the oscillations does not have to be part of the input sequence during the whole duration of the oscillations. Due to the categorical variable for the damping ratio, the surrogate can account for the influence of different damping in parameter studies.}, language = {en} } @article{LindnerPipaKarpenetal., author = {Lindner, Matthias and Pipa, Andrei V. and Karpen, Norbert and Hink, R{\"u}diger and Berndt, Dominik and Foest, R{\"u}diger and Bonaccurso, Elmar and Weichwald, Robert and Friedberger, Alois and Caspari, Ralf and Brandenburg, Ronny and Schreiner, Rupert}, title = {Icing Mitigation by MEMS-Fabricated Surface Dielectric Barrier Discharge}, series = {Applied Sciences}, volume = {11}, journal = {Applied Sciences}, number = {23}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app112311106}, pages = {1 -- 17}, abstract = {Avoiding ice accumulation on aerodynamic components is of enormous importance to flight safety. Novel approaches utilizing surface dielectric barrier discharges (SDBDs) are expected to be more efficient and effective than conventional solutions for preventing ice accretion on aerodynamic components. In this work, the realization of SDBDs based on thin-film substrates by means of micro-electro-mechanical-systems (MEMS) technology is presented. The anti-icing performance of the MEMS SDBDs is presented and compared to SDBDs manufactured by printed circuit board (PCB) technology. It was observed that the 35 mu m thick electrodes of the PCB SDBDs favor surface icing with an initial accumulation of supercooled water droplets at the electrode impact edges. This effect was not observed for 0.3 mu m thick MEMS-fabricated electrodes indicating a clear advantage for MEMS-technology SDBDs for anti-icing applications. Titanium was identified as the most suitable material for MEMS electrodes. In addition, an optimization of the MEMS-SDBDs with respect to the dielectric materials as well as SDBD design is discussed.}, language = {en} } @article{GamischHuberGadereretal., author = {Gamisch, Bernd and Huber, Lea and Gaderer, Matthias and Dawoud, Belal}, title = {On the Kinetic Mechanisms of the Reduction and Oxidation Reactions of Iron Oxide/Iron Pellets for a Hydrogen Storage Process}, series = {Energies}, volume = {15}, journal = {Energies}, number = {21}, publisher = {MDPI}, doi = {10.3390/en15218322}, abstract = {This work aims at investigating the kinetic mechanisms of the reduction/oxidation (redox) reactions of iron oxide/iron pellets under different operating conditions. The reaction principle is the basis of a thermochemical hydrogen storage system. To simulate the charging phase, a single pellet consisting of iron oxide (90\% Fe2O3, 10\% stabilising cement) is reduced with different hydrogen (H2) concentrations at temperatures between 600 and 800 °C. The discharge phase is initiated by the oxidation of the previously reduced pellet by water vapour (H2O) at different concentrations in the same temperature range. In both reactions, nitrogen (N2) is used as a carrier gas. The redox reactions have been experimentally measured in a thermogravimetric analyser (TGA) at a flow rate of 250 mL/min. An extensive literature review has been conducted on the existing reactions' kinetic mechanisms along with their applicability to describe the obtained results. It turned out that the measured kinetic results can be excellently described with the so-called shrinking core model. Using the geometrical contracting sphere reaction mechanism model, the concentration- and temperature-dependent reduction and oxidation rates can be reproduced with a maximum deviation of less than 5\%. In contrast to the reduction process, the temperature has a smaller effect on the oxidation reaction kinetics, which is attributed to 71\% less activation energy (Ea,Re=56.9 kJ/mol versus Ea,Ox=16.0 kJ/mol). The concentration of the reacting gas showed, however, an opposite trend: namely, to have an almost twofold impact on the oxidation reaction rate constant compared to the reduction rate constant.}, language = {en} } @article{KaessStrahringerWestner, author = {K{\"a}ss, Sebastian and Strahringer, Susanne and Westner, Markus}, title = {A Multiple Mini Case Study on the Adoption of Low Code Development Platforms in Work Systems}, series = {IEEE Access}, journal = {IEEE Access}, publisher = {IEEE}, issn = {2169-3536}, doi = {10.1109/ACCESS.2023.3325092}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-65634}, pages = {118762 -- 118786}, abstract = {Although adopting Low Code Development Platforms (LCDPs) promises significant efficiency and effectiveness improvements for application development, its adoption still needs further empirical research. This paper uses a combinatorial approach to research LCDP adoption and presents the results of a multiple mini case study with 36 cases on LCDP adoption. A combination of the Socio-Technical Systems theory and the Technology-Organisational-Environment model is used as a theoretical lens. In this paper, we show that LCDP adoption is a multifaceted phenomenon and identify three archetypes for LCDP adoption (i.e., IT Resource Shortage Mitigators, Application Development Democratisers, and Synergy Realisers) and one archetype for LCDP non-adoption (i.e., Intricacy Adversaries). Each archetype can be interpreted as an individual path towards LCDP (non-)adoption. Based on these archetypes, we derive seven starting points for practitioners to adopt LCDPs in work systems. Moreover, by using the theoretical lenses, the paper shows that for an LCDP adoption to occur, an optimisation of the social and technical sub-systems is required.}, language = {en} } @article{KrieglKravanjaHribaretal., author = {Kriegl, Raphael and Kravanja, Gaia and Hribar, Luka and Čoga, Lucija and Drevenšek-Olenik, Irena and Jezeršek, Matija and Kalin, Mitjan and Shamonin (Chamonine), Mikhail}, title = {Microstructured Magnetoactive Elastomers for Switchable Wettability}, series = {Polymers}, volume = {14}, journal = {Polymers}, number = {18}, publisher = {MDPI}, doi = {10.3390/polym14183883}, pages = {1 -- 21}, abstract = {We demonstrate the control of wettability of non-structured and microstructured magnetoactive elastomers (MAEs) by magnetic field. The synthesized composite materials have a concentration of carbonyl iron particles of 75 wt.\% (≈27 vol.\%) and three different stiffnesses of the elastomer matrix. A new method of fabrication of MAE coatings on plastic substrates is presented, which allows one to enhance the response of the apparent contact angle to the magnetic field by exposing the particle-enriched side of MAEs to water. A magnetic field is not applied during crosslinking. The highest variation of the contact angle from (113 ± 1)° in zero field up to (156 ± 2)° at about 400 mT is achieved in the MAE sample with the softest matrix. Several lamellar and pillared MAE structures are fabricated by laser micromachining. The lateral dimension of surface structures is about 50 µm and the depth varies between 3 µm and 60 µm. A systematic investigation of the effects of parameters of laser processing (laser power and the number of passages of the laser beam) on the wetting behavior of these structures in the absence and presence of a magnetic field is performed. In particular, strong anisotropy of the wetting behavior of lamellar structures is observed. The results are qualitatively discussed in the framework of the Wenzel and Cassie-Baxter models. Finally, directions of further research on magnetically controlled wettability of microstructured MAE surfaces are outlined. The obtained results may be useful for the development of magnetically controlled smart surfaces for droplet-based microfluidics.}, language = {en} } @article{LehrerKapsLepeniesetal., author = {Lehrer, Tobias and Kaps, Arne and Lepenies, Ingolf and Duddeck, Fabian and Wagner, Marcus}, title = {2S-ML: A simulation-based classification and regression approach for drawability assessment in deep drawing}, series = {International Journal of Material Forming}, volume = {16}, journal = {International Journal of Material Forming}, publisher = {Springer}, doi = {10.1007/s12289-023-01770-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-64664}, pages = {1 -- 17}, abstract = {New structural sheet metal parts are developed in an iterative, time-consuming manner. To improve the reproducibility and speed up the iterative drawability assessment, we propose a novel low-dimensional multi-fidelity inspired machine learning architecture. The approach utilizes the results of low-fidelity and high-fidelity finite element deep drawing simulation schemes. It hereby relies not only on parameters, but also on additional features to improve the generalization ability and applicability of the drawability assessment compared to classical approaches. Using the machine learning approach on a generated data set for a wide range of different cross-die drawing configurations, a classifier is trained to distinguish between drawable and non-drawable setups. Furthermore, two regression models, one for drawable and one for non-drawable designs are developed that rank designs by drawability. At instantaneous evaluation time, classification scores of high accuracy as well as regression scores of high quality for both regressors are achieved. The presented models can substitute low-fidelity finite element models due to their low evaluation times while at the same time, their predictive quality is close to high-fidelity models. This approach may enable fast and efficient assessments of designs in early development phases at the accuracy of a later design phase in the future.}, language = {en} } @article{MikhaeilNowakPalombaetal., author = {Mikhaeil, Makram and Nowak, Sebastian and Palomba, Valeria and Frazzica, Andrea and Gaderer, Matthias and Dawoud, Belal}, title = {Experimental and analytical investigation of applying an asymmetric plate heat exchanger as an evaporator in a thermally driven adsorption appliance}, series = {Applied Thermal Engineering}, journal = {Applied Thermal Engineering}, number = {228}, publisher = {Elsevier}, doi = {10.1016/j.applthermaleng.2023.120525}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-61115}, abstract = {This communication presents an experimental and analytical study on the evaporation mechanism in a closed-structured asymmetric plate heat exchanger (PHE) employed as a stagnant water evaporator for the application in an adsorption heat transformation appliance. To this aim, an experimental unit is constructed, which comprises two identical PHEs, one acting as an vaporator/condenser and the second, as an adsorber/desorber. Two endoscopes are mounted inside the investigated evaporator to visualize the evaporation mechanism when performing adsorption-evaporation processes under different boundary conditions. It turned out that the evaporation mechanism is a partially covered, thin film evaporation. A heat transfer analysis is performed to evaluate the heat transfer coefficient of the thin film evaporation () inside the investigated evaporator, resulting in -values between 1330 and 160 [W∙m-2∙K-1] over the investigated adsorption-evaporation time. Correlating the obtained () to the film thickness and the wetted area results in -values between 0.34 and 0.78 [mm] and wetted to total area ratios of 0.78 to 0.16. Besides, an analytical model has been developed and introduced to correlate the overall evaporator heat transfer coefficient with the adsorption potential and the time rate of change of the water uptake.}, language = {en} } @inproceedings{KaramaraBogdanskiZoelleretal., author = {Karamara, Merve and Bogdanski, Moritz-Ole and Z{\"o}ller, Raphael and Albrecht, Sophie Viktoria and Linner, Thomas and Bock, Thomas and Braml, Thomas}, title = {Increasing efficiency and sustainability: A comparative analysis of concrete 3D printing and traditional methods based on case studies}, series = {MATEC Web of Conferences}, volume = {409}, booktitle = {MATEC Web of Conferences}, publisher = {EDP Sciences}, doi = {10.1051/matecconf/202540913005}, pages = {7}, abstract = {At the forthcoming Concrete Solutions 2025 conference, the subject of concrete 3D printing will be explored in the "Case Studies" category, with a comparison to traditional methods. Concrete 3D printing offers several significant advantages, including the ability to create complex geometries, increased material efficiency, faster build times and cost savings. These are particularly important in the context of the current skilled labour shortage and emphasis on resource efficiency in construction. Nevertheless, challenges persist in the areas of machine reliability, process integration, and material adaptation to meet the requirements of 3D printing. The case studies will present modular and design-engineering-based strategies for the development of efficient, scalable automation solutions that integrate 3D printing into existing processes and allow for project-specific customisation through selective automation. These findings provide a robust framework for industrial applications that enhance efficiency and adaptability. By comparing concrete 3D printing to conventional methods, the insights offer a foundation for advancing automated production in construction, promoting scalable, resource-efficient, and economically sustainable practices that address the industry's evolving demands.}, language = {en} } @article{FrankeWagnerKrause, author = {Franke, Markus and Wagner, Marcus and Krause, Tom Janis}, title = {Data-driven model order reduction with surrogate elements for transient simulations}, series = {Engineering Computations : International journal for computer-aided engineering and software}, volume = {2025}, journal = {Engineering Computations : International journal for computer-aided engineering and software}, publisher = {Emerald Publishing}, address = {Leeds}, doi = {10.1108/EC-06-2024-0511}, pages = {26}, abstract = {Purpose - The purpose of this study is to introduce surrogate elements for static and transient finite element simulations. These elements are designed to replace regions of several conventional solid elements with a single artificial element that possesses a reduced number of degrees of freedoms (dofs). A notable advantage of our surrogate elements is their seamless integration into standard finite element meshes. Design/methodology/approach - The construction of the surrogate elements stiffness and mass matrices is achieved through an optimization process wherein displacements serve as the optimization objective. Moreover, the matrices are designed to possess properties analogous to those of standard finite elements. A particular focus is placed on ensuring that the artificial stiffness matrices are positive semi-definite. Furthermore, artificial degrees of freedom are introduced. Findings - The efficacy of the proposed technique is demonstrated through its application to two different use cases. It is demonstrated that, despite being trained on examples comprising a single surrogate element, the surrogate elements can be employed multiple times within complex and practical models. The degree of accuracy achieved in these applications is noteworthy. Moreover, the proposed method is considerably faster than the fully discretized models. Originality/value - The study expands the field of substructuring and model order reduction by incorporating artificial surrogate elements built by neural networks, which enables seamless integration with standard finite element analysis via positive semi-definite matrices. Furthermore, the introduction of artificial degrees of freedom, which are detached from the computational domain, is proposed. Once trained, the surrogate elements can be utilised in load and support independent scenarios.}, language = {en} } @article{HillebrandWestnerMatschi, author = {Hillebrand, Patrick and Westner, Markus and Matschi, Markus}, title = {Schl{\"u}sselfaktoren erfolgreicher CIOs}, series = {HMD Praxis der Wirtschaftsinformatik}, volume = {59}, journal = {HMD Praxis der Wirtschaftsinformatik}, publisher = {Springer Nature}, doi = {10.1365/s40702-022-00867-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-33751}, pages = {762 -- 779}, abstract = {Die vorliegende Studie untersucht Schl{\"u}sselfaktoren erfolgrei- cher CIOs in deutschen Großunternehmen. Mit einer mittleren Verweildauer (Median) von 4,0 Jahren weisen deutsche CIOs, die mit 43 \% noch {\"u}berwiegend an den CFO berichten, im Vergleich zu anderen C-Level-Positionen eine deutlich k{\"u}rzere Verweildauer im Amt auf. Die Ergebnisse aus 60 Interviews mit erfolgreichen deutschsprachigen CIOs, die prim{\"a}r {\"u}ber eine {\"u}berdurchschnittlich lange Verweildauer verf{\"u}gen, lassen verschiedene Schl{\"u}sselfaktoren f{\"u}r den Erfolg erkennen: Grundvoraussetzung ist stets die Gew{\"a}hrleistung eines sicheren und effizienten IT-Betriebs. {\"U}ber effektive und innovative Change-Projekte machen die interviewten CIOs den IT-Mehrwert transparent und agieren als Br{\"u}ckenbauer zwischen IT und Fachbereichen. Dadurch wirken sie positiv auf die Firmenkultur ein und etablieren die IT nachhaltig in den Fachbereichen als Erfolgsfaktor. Erfolgreiche CIOs selbst sind keine „Techies", sondern zeichnen sich durch hohe F{\"u}hrungskompetenz und ein hohes Gesch{\"a}ftsverst{\"a}ndnis, gepaart mit vision{\"a}rem Denken aus. Dadurch gelingt es ihnen, die IT zukunftsorientiert auszurichten und Anforderungen und Potenziale f{\"u}r und aus den Fachbereichen fr{\"u}hzeitig zu antizipieren. Die zuk{\"u}nftige Entwicklung der CIO-Organisation und der Paradigmen in der IT wird durch die Studienteilnehmer hingegen teilweise kontrovers diskutiert - so gibt es beispielsweise bei der Beurteilung der Sinnhaftigkeit und Relevanz der CDO-Position noch kein einheitliches Meinungsbild.}, language = {de} } @article{ThumannBuchnerMarburgetal., author = {Thumann, Philipp and Buchner, Stefan and Marburg, Steffen and Wagner, Marcus}, title = {A comparative study of Glinka and Neuber approaches for fatigue strength assessment on 42CrMoS4-QT specimens}, series = {Strain}, volume = {2023}, journal = {Strain}, number = {e12470}, publisher = {Wiley}, issn = {1475-1305}, doi = {10.1111/str.12470}, pages = {21}, abstract = {In fatigue strength assessment, the methods based on ideal elastic stresses according to Basquin and the less established method based on elastic-plastic stress quantities according to Manson, Coffin and Morrow are applied. The former calculates loads using linear-elastic stresses, the latter requires elasticplastic evaluation parameters, such as stresses and strains. These can be determined by finite element analysis (FEA) with a linear-elastic constitutive law, and subsequent conversion to elastic-plastic loads, using the macro support formula by Neuber. In this contribution, an alternative approach to approximate elastic-plastic parameters proposed by Glinka is compared to the the strain-life method using Neuber's formula, as well as the stress-life method of Basquin. Several component tests on 42CrMoS4-QT specimens are investigated. To determine the input data for the fatigue strength evaluations, the entire test setup is computed by FEA. The nodal displacements from these validated full-model simulations are used as boundary conditions for a submodel simulation of a notch, whose results serve as input for the fatigue strength assessments. It is shown that all approaches provide a reliable assessment of components. Our key result is that the strain-life method using the concept by Glinka for notch stress computation, yields improved results in fatigue strength assessments.}, language = {en} } @article{SchuheggerKaraGalkaetal., author = {Schuhegger, Lukas and Kara, Sinan and Galka, Stefan and D{\"u}nnweber, Jan and Meißner, Sebastian}, title = {Umzugsplanung mit Fabrikdatenmodellen und Virtual Reality}, series = {Zeitschrift f{\"u}r wirtschaftlichen Fabrikbetrieb}, volume = {119}, journal = {Zeitschrift f{\"u}r wirtschaftlichen Fabrikbetrieb}, number = {11}, publisher = {de Gruyter}, issn = {2511-0896}, doi = {10.1515/zwf-2024-1154}, pages = {799 -- 804}, abstract = {Angesichts eines dynamischen industriellen Umfelds m{\"u}ssen produzierende Unternehmen flexibel bleiben und sich kontinuierlich anpassen, um ihre Wettbewerbsf{\"a}higkeit zu erhalten. Eine effektive Planung von Restrukturierungen in Produktionssystemen, oft als Umzugsplanung bezeichnet, ist entscheidend, um Verz{\"o}gerungen zu vermeiden und Stillstandszeiten zu minimieren. Die Identifikation von Umzugsf{\"a}llen, welche den Umfang umzuziehender Ressourcen wie Maschinen, Anlagen, Ausr{\"u}stungen und Arbeitspl{\"a}tzen beschreiben und die Definition zugeh{\"o}riger Aufgaben sind essenzielle Schritte der Umzugsplanung. Dieser Beitrag stellt eine Vorgehensweise zur Bestimmung von Umzugsf{\"a}llen mittels eines Fabrikdatenmodells vor, erg{\"a}nzt durch eine Visualisierung in Virtual Reality, um Planende bei der Umzugsplanung zu unterst{\"u}tzen.}, language = {de} } @article{SchmidbauerBeckerHaug, author = {Schmidbauer, Simon and Becker, Maria and Haug, Sonja}, title = {Online Political Participation of Refugees in Germany: Analysis of a Survey in Bavaria}, series = {Sage Online}, journal = {Sage Online}, publisher = {Sage}, address = {Thousand Oaks}, doi = {10.1177/21582440241286303}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77671}, abstract = {New media are an important resource for the political participation of marginalized groups. However, there is still a lack of knowledge about the factors that influence whether this opportunity is used. Influencing factors emerge from both the Civic Voluntarism Model and previous research on migrants' political activity. Using data collected in 2019/2020 from 486 refugees living in Bavaria, we estimate linear probability models to investigate facilitating factors for the use of new media for political participation. The analysis shows that refugees in Germany who inform themselves about politics online tend to be predominantly male, higher educated, and politically involved. Language skills and the duration of stay also appear to be important. For the expression of one's political opinion online, gender and language skills have an impact, but informing oneself about German politics, political interest, and offline political activity in Germany are the most relevant factors. This indicates that there is a close link between on- und offline activity. However, using the internet requires particular resources, so that people with lower language skills, for example, are particularly disadvantaged.}, language = {de} } @article{GradSchultheissDiemaretal., author = {Grad, Marius and Schultheiß, Ulrich and Diemar, Andreas and Spieß, Lothar and Noster, Ulf}, title = {Preparation methodology for the microstructural characterization of diffusion layers in a titanium/steel composite}, series = {Practical Metallography}, volume = {61}, journal = {Practical Metallography}, number = {12}, publisher = {Walter de Gruyter GmbH}, issn = {2195-8599}, doi = {10.1515/pm-2024-0087}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-78346}, pages = {938 -- 946}, abstract = {Hot pressing of titanium and carbon steel leads to the formation of a diffusion layer at the interface. Depending on the carbon content of the steel used, it either exclusively contains TiC or additional other phases. In the case of steel with a medium carbon concentration (0.67 wt.\% C), a pure TiC layer forms. A preparation methodology was developed to make statements about functional and microstructural properties of the respective layers such as layer thickness, porosity, or grain size. However, apart from the diffusion layer's microstructure, it also reveals the microstructure of the two base substrates. A comparison based on electron backscatter diffraction (EBSD) examinations yields similar results in terms of microstructure. A micrograph analysis based on the new preparation methodology also allows confirming the element distribution measurement by glow discharge optical emission spectroscopy (GDOES). The methodology therefore provides a way of quickly and reliably controlling the layer formation during the hot pressing process of titanium and carbon steel.}, language = {en} } @article{PangerlMoserMuelleretal., author = {Pangerl, Jonas and Moser, Elisabeth and M{\"u}ller, Max and Weigl, Stefan and Jobst, Simon and R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {A sub-ppbv-level Acetone and Ethanol Quantum Cascade Laser Based Photoacoustic Sensor- Characterization and Multi-Component Spectra Recording in Synthetic Breath}, series = {Photoacoustics}, volume = {30}, journal = {Photoacoustics}, publisher = {Elsevier}, issn = {2213-5979}, doi = {10.1016/j.pacs.2023.100473}, pages = {1 -- 12}, abstract = {Trace gas analysis in breath is challenging due to the vast number of different components. We present a highly sensitive quantum cascade laser based photoacoustic setup for breath analysis. Scanning the range between 8263 and 8270 nm with a spectral resolution of 48 pm, we are able to quantify acetone and ethanol within a typical breath matrix containing water and CO2. We photoacoustically acquired spectra within this region of mid-infra-red light and prove that those spectra do not suffer from non-spectral interferences. The purely additive behavior of a breath sample spectrum was verified by comparing it with the independently acquired single component spectra using Pearson and Spearman correlation coefficients. A previously presented simulation approach is improved and an error attribution study is presented. With a 3σ detection limit of 6.5 ppbv in terms of ethanol and 250 pptv regarding acetone, our system is among the best performing presented so far.}, language = {en} } @article{RauchBrueckl, author = {Rauch, Johannes and Br{\"u}ckl, Oliver}, title = {Achieving Optimal Reactive Power Compensation in Distribution Grids by Using Industrial Compensation Systems}, series = {Electricity}, volume = {4}, journal = {Electricity}, number = {1}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/electricity4010006}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-59139}, pages = {78 -- 95}, abstract = {This paper presents a method for integrating industrial consumers owning compensation systems as alternative reactive power sources into grid operating processes. In remuneration, they receive a market-based provision of reactive power. The aim is to analyze the potential of reactive power compensation systems of industrial companies connected to medium-voltage (10 kV-30 kV) AC grids in order to increase the reactive power ability of distribution grids. Measurement methods and reactive power potential results of six industrial companies are presented to characterize the amount and temporal availability of their reactive power potential. The presented approach for using the decentralized reactive power potential is a centralized reactive power control method and is based on optimal power flow (OPF) calculations. An optimization algorithm based on linear programming is used to coordinate a reactive power retrieval tuned to the actual demand. The influencing quantities are the current grid status (voltage and load flow capacity reserves at grid nodes and power lines) and the current reactive power potential of the reactive power sources. The compensation impact of six measured industrial companies on an exemplary medium-voltage grid is shown by an application example.}, language = {en} } @inproceedings{PfahlerThielNeidhart, author = {Pfahler, Katharina and Thiel, Charlotte and Neidhart, Thomas}, title = {Einfluss der Probengeometrie auf die Mechanischen Eigenschaften von Stampflehm - Eine Literaturrecherche}, series = {ce/papers - Proceedings in Civil Engineering}, volume = {8}, booktitle = {ce/papers - Proceedings in Civil Engineering}, number = {1}, publisher = {Ernst \& Sohn, a Wiley Brand}, issn = {2509-7075}, doi = {10.1002/cepa.3291}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-80291}, pages = {57 -- 68}, abstract = {Der Klimawandel lenkt den Fokus im Bauwesen zunehmend auf die Reduktion von Treibhausgasen und die F{\"o}rderung nachhaltiger Materialien. Baustoffe wie Lehm gewinnen dank ihrer {\"o}kologischen und bauphysikalischen Vorteile an Bedeutung. Eine zentrale Herausforderung stellt die Definition standardisierter Pr{\"u}fmethoden f{\"u}r Stampflehm dar. Dieser Beitrag analysiert Forschungsergebnisse zur Geometrie von Stampflehmprobek{\"o}rpern mittels Literaturrecherche und vergleicht experimentelle Untersuchungen sowie relevante Normen und Testmethoden. Die Auswertung zeigt, dass {\"a}ußere Einfl{\"u}sse wie Mischungszusammensetzung, Verdichtungsenergie, Gesteinsk{\"o}rnung und Tonminerale eine zentrale Rolle spielen. Eine Vereinheitlichung von Probengeometrie, Lagerung und Pr{\"u}fverfahren ist essenziell, um reproduzierbare Ergebnisse zu erzielen und die mechanischen Kennwerte von Stampflehm vergleichbar zu machen. Ziel ist es, einheitliche Standards zu entwickeln, um die Stampflehmbauweise in der Praxis zu f{\"o}rdern.}, subject = {Lehmbau}, language = {de} } @article{RoehrlStauferBugertetal., author = {R{\"o}hrl, Simon and Staufer, Susanne and Bugert, Flemming and Nadimpalli, Vamsi Krishna and Hauser, Florian and Grabinger, Lisa and Bittner, Dominik and Ezer, Timur and Altweck, Ricardo and Graf, Sabine and Kriza, Thomas and Mottok, J{\"u}rgen}, title = {Ethical Considerations of AI in Education: A Case Study based on Pythia Learning Enhancement System}, series = {IEEE Access}, volume = {11}, journal = {IEEE Access}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, issn = {2169-3536}, doi = {10.1109/ACCESS.2025.3583975}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-83403}, pages = {1 -- 25}, abstract = {As the use of AI in education increases, addressing ethical concerns is essential for its responsible use and implementation. This study explores the ethical considerations of AI in education by analyzing a concrete application, the Pythia Learning Enhancement System, which enables personalized and adaptive educational experiences. In this case study, the concrete implementation of Pythia, contrary to high-level abstract analyses, provides practical insights into these ethical issues. To achieve this goal, we first define Pythia and outline its implementation. Using the various topics covered by Pythia, the ethical issues associated with each of these topics are outlined, resulting in a list of ten distinct ethical issues. Because there is overlap in issues covered by similar applications, they can benefit from this identification. An ethical (human rights) and didactic (constructivism) theoretical background is then provided as a basis for further discussion. This is used to build the arguments used in the main study. This consists of analyzing each of the issues and providing recommendations to mitigate potential harm arising from these issues. This helps to provide guidelines for future applications. In the analysis, the ethical discussion is mainly based on the human rights of the stakeholders involved, emphasizing human dignity. After the analysis, each of the issues is contextualized with the recent AI Act of the European Union, providing a novel mapping of the issues of AI in education to the AI Act. Finally, the limitations of the study are stated and a plan for future research is presented.}, language = {en} } @article{GaertnerRankHeberletal., author = {G{\"a}rtner, Sebastian and Rank, Daniel and Heberl, Michael and Gaderer, Matthias and Dawoud, Belal and Haumer, Anton and Sterner, Michael}, title = {Simulation and Techno-Economic Analysis of a Power-to-Hydrogen Process for Oxyfuel Glass Melting}, series = {Energies}, volume = {14}, journal = {Energies}, number = {24}, publisher = {MDPI}, doi = {10.3390/en14248603}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-22713}, abstract = {As an energy-intensive industry sector, the glass industry is strongly affected by the increasingly stringent climate protection targets. As established combustion-based production systems ensure high process stability and glass quality, an immediate switch to low greenhouse gas emission processes is difficult. To approach these challenges, this work investigates a step-by-step integration of a Power-to-Hydrogen concept into established oxyfuel glass melting processes using a simulation approach. This is complemented by a case study for economic analysis on a selected German glass industry site by simulating the power production of a nearby renewable energy park and subsequent optimization of the power-to-hydrogen plant performance and capacities. The results of this study indicate, that the proposed system can reduce specific carbon dioxide emissions by up to 60\%, while increasing specific energy demand by a maximum of 25\%. Investigations of the impact of altered combustion and furnace properties like adiabatic flame temperature (+25 °C), temperature efficiency (∆ξ = -0.003) and heat capacity flow ratio (∆zHL = -0.009) indicate that pure hydrogen-oxygen combustion has less impact on melting properties than assumed so far. Within the case study, high CO2 abatement costs of 295 €/t CO2-eq. were determined. This is mainly due to the insufficient performance of renewable energy sources. The correlations between process scaling and economic parameters presented in this study show promising potential for further economic optimization of the proposed energy system in the future.}, language = {en} } @article{ReichenederWestnerMatschi, author = {Reicheneder, Matthias and Westner, Markus and Matschi, Markus}, title = {IT-Near- und Offshoring in deutschen Großunternehmen: Aktueller Stand, Motive und Auswahlkriterien}, series = {HMD Praxis der Wirtschaftsinformatik}, journal = {HMD Praxis der Wirtschaftsinformatik}, publisher = {Springer Nature}, address = {Wiesbaden}, issn = {1436-3011}, doi = {10.1365/s40702-025-01150-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-79582}, pages = {19}, abstract = {Die vorliegende Studie untersucht die aktuelle IT-Near- und Offshoring-Praxis in deutschen Großunternehmen. Daf{\"u}r wurden 33 CIOs und IT-F{\"u}hrungskr{\"a}fte mittels Interviews befragt. Haupttreiber der geografischen Verlagerung von IT-Services ins Ausland ist die Ressourcenverf{\"u}gbarkeit in anderen L{\"a}ndern, bedingt durch den Fachkr{\"a}ftemangel in Deutschland. Dies trifft auch auf die Auswahl geeigneter IT-Services f{\"u}r das Near- und Offshoring zu. W{\"a}hrend IT-Near- und Offshoring historisch prim{\"a}r aufgrund von Kosteneinsparungen initiiert wurde, spielt dieser Aspekt heute eine untergeordnete Rolle. Die Interviewteilnehmer und -teilnehmerinnen sehen in Kosteneinsparungen zwar immer noch einen positiven Effekt, erwarten aber, dass dieser in Zukunft aufgrund der Angleichung des Kostenniveaus schwinden wird. Die Unternehmen verlagern haupts{\"a}chlich Applikationsbetrieb und -entwicklung, erkennen jedoch zunehmend das Potenzial, auch h{\"o}herwertige Aufgaben, z. B. Projektmanagement und Unternehmensarchitekturmanagement, aus geografisch entfernteren L{\"a}ndern erbringen zu lassen. Unternehmen, die ausschließlich IT-Nearshoring betreiben, erbringen weniger als ein Drittel ihrer IT-Services aus nahegelegenen L{\"a}ndern. Firmen mit IT-Offshoring-Pr{\"a}senzen weisen einen h{\"o}heren IT-Near‑/Offshoringgrad auf und verlagern knapp die H{\"a}lfte der eigenen IT-Serviceerbringung ins Ausland. Die beliebtesten L{\"a}nder sind Portugal f{\"u}r das Nearshoring und Indien f{\"u}r das Offshoring.}, language = {de} } @article{MauererJoblinTamburrietal., author = {Mauerer, Wolfgang and Joblin, Mitchell and Tamburri, Damian and Paradis, Carlos and Kazman, Rick and Apel, Sven}, title = {In Search of Socio-Technical Congruence: A Large-Scale Longitudinal Study}, series = {IEEE Transactions on Software Engineering (TSE)}, volume = {48}, journal = {IEEE Transactions on Software Engineering (TSE)}, number = {8}, publisher = {IEEE}, doi = {10.1109/TSE.2021.3082074}, pages = {3159 -- 3184}, abstract = {This paper describes a large-scale empirical study investigating the relevance of socio-technical congruence over key basic software quality metrics, namely, bugs and churn. That is, we explore whether alignment or misalignment of social communication structures and technical dependencies in large software projects influences software quality. To this end, we have defined a quantitative and operational notion of socio-technical congruence, which we call /socio-technical motif congruence/ (STMC). STMC is a measure of the degree to which developers working on the same file or on two related files, need to communicate. As socio-technical congruence is a complex and multi-faceted phenomenon, the interpretability of the results is one of our main concerns, so we have employed a careful mixed-methods statistical analysis. In particular, we provide analyses with similar techniques as employed by seminal work in the field to ensure comparability of our results with the existing body of work. The major result of our study, based on an analysis of 25 large open-source projects, is that STMC is /not/ related to project quality measures---software bugs and churn---in any temporal scenario. That is, we find no statistical relationship between the alignment of developer tasks and developer communications on one hand, and project outcomes on the other hand. We conclude that, wherefore congruence does matter as literature shows, then its measurable effect lies elsewhere.}, language = {en} } @article{HofrichterRankHeberletal., author = {Hofrichter, Andreas and Rank, Daniel and Heberl, Michael and Sterner, Michael}, title = {Determination of the optimal power ratio between electrolysis and renewable energy to investigate the effects on the hydrogen production costs}, series = {International Journal of Hydrogen Energy}, volume = {48}, journal = {International Journal of Hydrogen Energy}, number = {5}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2022.09.263}, pages = {1651 -- 1663}, abstract = {Green hydrogen via renewable powered electrolysis has a high relevance in decarbonization and supply security. Achieving economically competitive hydrogen production costs is a major challenge in times of an energy price crisis. Our objective is to show the economically optimal installed capacity of electrolysers in relation to wind and solar power so swift and credible statements can be made regarding the system design. The ratio between renewable generation and electrolysis power as well as scaling effects, operating behaviour and development of costs are considered. Hydrogen production costs are calculated for four exemplary real PV and wind sites and different ratios of electrolysis to renewable power for the year 2020. The ideal ratio for PV systems is between 14\% and 73\% and for wind between 3.3\% and 143\% for low and high full load hours. The lowest hydrogen production costs are identified at 2.53 €/kg for 50 MW wind power and 72 MW electrolysis power. The results provide plant constructors the possibility to create a cost-optimized design via an optimum ratio of electrolysis to renewable capacity. Therefore, the procedures for planning and dimensioning of selected systems can be drastically simplified.}, language = {en} }