TY - JOUR A1 - Pangerl, Jonas A1 - Sukul, Pritam A1 - Rück, Thomas A1 - Fuchs, Patricia A1 - Weigl, Stefan A1 - Miekisch, Wolfram A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - An inexpensive UV-LED photoacoustic based real-time sensor-system detecting exhaled trace-acetone JF - Photoacoustics N2 - n this research we present a low-cost system for breath acetone analysis based on UV-LED photoacoustic spectroscopy. We considered the end-tidal phase of exhalation, which represents the systemic concentrations of volatile organic compounds (VOCs) – providing clinically relevant information about the human health. This is achieved via the development of a CO2-triggered breath sampling system, which collected alveolar breath over several minutes in sterile and inert containers. A real-time mass spectrometer is coupled to serve as a reference device for calibration measurements and subsequent breath analysis. The new sensor system provided a 3σ detection limit of 8.3 ppbV and an NNEA of 1.4E-9 Wcm 1Hz 0.5. In terms of the performed breath analysis measurements, 12 out of 13 fell within the error margin of the photoacoustic measurement system, demonstrating the reliability of the measurements in the field. KW - Photoacoustic spectroscopy KW - Real-time mass-spectrometry KW - Breath analysis KW - Acetone KW - UV-LED Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-71279 SN - 2213-5979 N1 - Corresponding author der OTH Regensburg: Jonas Pangerl VL - 38 PB - Elsevier 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 - Haug, Sonja A1 - Altenbuchner, Amelie A1 - Weber, Karsten T1 - Elektronische Patientenakte und Freigabe von Gesundheitsdaten BT - Die Einstellung von Personen in Haushalten mit Kindern,The Attitude of Persons in Households with Children JF - Pädiatrie & Pädologie N2 - Hintergrund In Deutschland wird die elektronische Patientenakte (ePA) eingeführt. Fragestellung Untersucht werden Nutzungsbereitschaft der ePA, Einstellung zu Gesundheitsdaten und Datenübermittlung bei Personen mit und ohne Kinder. Methoden Telefonbefragung bei einer Zufallsstichprobe der Bevölkerung in Deutschland (2022, n = 1308). Ergebnisse Die ePA ist bei Haushalten mit Kindern mehrheitlich unbekannt. Ihre Nutzungsbereitschaft der ePA und die Zustimmung zur Speicherung von Gesundheitsdaten ist geringer, aber sie sind häufiger als Haushalte ohne Kinder bereit zur Freigabe ihrer Gesundheitsdaten für die Forschung. Schlussfolgerung Es besteht Aufklärungsbedarf über die Speicherung von Gesundheitsdaten. Gewünscht wird zunehmend eine digitale Arzt-Patienten-Kommunikation. KW - Gesundheitsregister KW - Elektronische Patientenakte KW - Forschungsdaten KW - Kommunikation im Gesundheitswesen KW - Versorgungsmanagement Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-73847 SN - 0030-9338 N1 - Corresponding author der OTH REgensburg: Sonja Haug PB - Springer ER - TY - JOUR A1 - Hausler, Peter A1 - Holzner, Lukas A1 - Ehrnsperger, Matthias A1 - Bierl, Rudolf T1 - Evaluation of the creep strength of samples produced by fused deposition modeling JF - Open Engineering N2 - Data sheets for 3D printing materials typically include softening temperature, impact strength, tensile strength, and stiffness. However, creep strength, an important parameter for components used over an extended period, is usually not included. Nevertheless, this parameter is of significant importance for components that are used over an extended period of time.This study compares the long-term creep behavior of a selection of materials that are commonly used in fused deposition modeling 3D printing. The materials under investigation are acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, polylactic acid, and polycarbonate. In addition, the influence of fiber reinforcements on these materials is also examined. A simple, reproducible test procedure is proposed for users to determine and compare creep resistance of materials. This enables developers to select materials suitable for their own requirements on creep resistance and allows 3D-printing users to compare different materials. Results suggest that fiber reinforcement generally improves creep stability in 3D-printing materials, with GreenTEC Pro Carbon and add:north PC Blend HT LCF showing the most promise in this study. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-79760 N1 - Corresponding author der OTH Regensburg: Peter Hausler VL - 14 IS - 1 PB - de Gruyter ER - TY - JOUR A1 - Pongratz, Christian A1 - Tix, Janek A1 - Wolfrum, Johannes A1 - Gerke, Steffen A1 - Ehrlich, Ingo A1 - Brünig, Michael T1 - Test Setup for Investigating the Impact Behavior of Biaxially Prestressed Composite Laminates JF - Experimental Techniques N2 - Instrumented impact testing and compression-after-impact testing are important to adequately qualify material behavior and safely design composite structures. However, the stresses to which fiber-reinforced plastic components are typically subjected in practice are not considered in the impact test methods recommended in guidelines or standards. In this paper, a test setup for investigating the impact behavior of composite specimens under plane uniaxial and biaxial preloading is presented. For this purpose, a special test setup consisting of a biaxial testing machine and a specially designed drop-weight tower was developed. The design decisions were derived from existing guidelines and standards with the aim of inducing barely visible impact damage in laminated carbon fiber-reinforced plastic specimens. Several measurement systems have been integrated into the setup to allow comprehensive observation of the impact event and specimen behavior. A feasibility test was performed with biaxially prestressed carbon fiber-reinforced plastic specimens in comparison with unstressed reference tests. The compressive-tensile prestressing resulted in lower maximum contact forces, higher maximum deflections, higher residual deflections and a different damage pattern, which was investigated by light microscopic analysis. Finally, the functionality of the experimental setup is discussed, and the results seem to indicate that the test setup and parameters were properly chosen to investigate the effect of prestresses on the impacts behavior of composite structures, in particular for barely visible subsequent damages. KW - Mechanical Engineering KW - Mechanics of Materials KW - Faserverbundwerkstoff KW - Schlagprüfung Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-70355 SN - 0732-8818 N1 - Corresponding authors: Christian Pongratz und Ingo Ehrlich PB - Springer Nature ER - TY - JOUR A1 - Grad, Marius A1 - Zentgraf, Jan A1 - Schultheiss, Ulrich A1 - Esper, Lukas A1 - Diemar, Andreas A1 - Noster, Ulf A1 - Spiess, Lothar T1 - Effect of Carbon Content on the Phase Composition, Microstructure and Mechanical Properties of the TiC Layer Formed in Hot-Pressed Titanium-Steel Composites JF - Metals N2 - During the hot pressing of pure titanium and different carbon steels in a temperature range of ϑ = 950–1050 °C, a compound layer up to dL≈10 μm thick is formed at the titanium–steel interface. With a higher carbon content of the used steel, the layer thickness increases. The carbon concentration within the layer is in the range of stoichiometry for TiC. Apart from TiC, no other phases can be detected by X-ray diffraction (XRD) measurements inside the formed layer. The calculation of the activation energy for the TiC layer formation is Q = 126.5–136.7 kJ mol−1 and is independent of the carbon content of the steel. The resulting microstructure has a grain size gradient, wherein the mechanical properties, such as hardness and Young‘s modulus, are almost constant. Statistical analysis using Response Surface Methodology (RSM) indicates that the carbon content of the steel has the most significant influence on layer thickness, followed by annealing temperature and annealing time. By selecting the appropriate carbon steel and the subsequent removal of the steel, it is possible to produce targeted TiC layers on titanium substrates, which holds enormous potential for this material in wear-intensive applications. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-74617 SN - 2075-4701 N1 - Cooresponding author der OTH Regensburg: Marius Grad VL - 14 IS - 9 PB - MDPI AG ER - TY - JOUR A1 - Auer, Simon A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Using markerless motion capture and musculoskeletal models: An evaluation of joint kinematics JF - Technology and Health Care N2 - BACKGROUND: This study presents a comprehensive comparison between a marker-based motion capture system (MMC) and a video-based motion capture system (VMC) in the context of kinematic analysis using musculoskeletal models. OBJECTIVE: Focusing on joint angles, the study aimed to evaluate the accuracy of VMC as a viable alternative for biomechanical research. METHODS: Eighteen healthy subjects performed isolated movements with 17 joint degrees of freedom, and their kinematic data were collected using both an MMC and a VMC setup. The kinematic data were entered into the AnyBody Modelling System, which enables the calculation of joint angles. The mean absolute error (MAE) was calculated to quantify the deviations between the two systems. RESULTS: The results showed good agreement between VMC and MMC at several joint angles. In particular, the shoulder, hip and knee joints showed small deviations in kinematics with MAE values of 4.8∘, 6.8∘ and 3.5∘, respectively. However, the study revealed problems in tracking hand and elbow movements, resulting in higher MAE values of 13.7∘ and 27.7∘. Deviations were also higher for head and thoracic movements. CONCLUSION: Overall, VMC showed promising results for lower body and shoulder kinematics. However, the tracking of the wrist and pelvis still needs to be refined. The research results provide a basis for further investigations that promote the fusion of VMC and musculoskeletal models. KW - biomechanics KW - range of motion KW - musculoskeletal system KW - optical motion capture Y1 - 2024 U6 - https://doi.org/10.3233/THC-240202 SN - 0928-7329 N1 - Corresponding author der OTH Regensburg: Sebastian Dendorfer SP - 1 EP - 10 PB - IOS Press ER - TY - JOUR A1 - Loo, Xuyan A1 - Nagaraju, Bhavana A1 - Pathivada, Sai A1 - Bartsch, Alexander A1 - Schratzenstaller, Thomas A1 - Sattler, Robert A1 - Monkman, Gareth J. T1 - Electrical properties of bisphenol-A-free magnetoactive borosilicate polymers JF - AIP Advances N2 - The recent REACH regulations require the elimination of bisphenol-A and titanium dioxide from commercially available boron-based polymers. This has led to changes in some of the mechanical characteristics, which strongly influence the properties of magnetoactive borosilicate polymers. This work delivers results on the electrical properties and discusses some implications for future research using bisphenol-A and titanium-dioxide-free substitutes. KW - Electrical components KW - Electrical properties and parameters KW - Dielectric properties KW - Electrical resistivity KW - Magnetic materials KW - Viscoelasticity KW - Polymers KW - Non Newtonian fluids KW - Magnetic fluids Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-72936 SN - 2158-3226 N1 - Corresponding author der OTH Regensburg: Gareth J. Monkman VL - 14 IS - 5 PB - AIP Publishing ER - TY - JOUR A1 - Tauwald, Sandra Melina A1 - Erzinger, Florian A1 - Quadrio, Maurizio A1 - Rütten, Markus A1 - Stemmer, Christian A1 - Krenkel, Lars T1 - Tomo-PIV in a patient-specific model of human nasal cavities: a methodological approach JF - Measurement Science and Technology N2 - The human nose serves as the primary gateway for air entering the respiratory system and plays a vital role in breathing. Nasal breathing difficulties are a significant health concern, leading to substantial healthcare costs for patients. Understanding nasal airflow dynamics is crucial for comprehending respiratory mechanisms. This article presents a detailed study using tomo-Particle Image Velocimetry (PIV) to investigate nasal airflow dynamics while addressing its accuracy. Embedded in the OpenNose project, the work described aims to provide a validation basis for different numerical approaches to upper airway flow. The study includes the manufacturing of a transparent silicone model based on a clinical CT scan, refractive index matching to minimize optical distortions, and precise flow rate adjustments based on physiological breathing cycles. This method allows for spatial high-resolution investigations in different regions of interest within the nasopharynx during various phases of the breathing cycle. The results demonstrate the accuracy of the investigations, enabling detailed analysis of flow structures and gradients. This spatial high-resolution tomo-PIV approach provides valuable insights into the complex flow phenomena occurring during the physiological breathing cycle in the nasopharynx. The study's findings contribute to advancements in non-free-of-sight experimental flow investigation of complex cavities under nearly realistic conditions. Furthermore, reliable and accurate experimental data is crucial for properly validating numerical approaches that compute this patient-specific flow for clinical purposes. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-70393 N1 - Corresponding author: Sandra Melina Tauwald VL - 35 IS - 5 PB - IOP Publishing ER - TY - CHAP A1 - Currle, Edda A1 - Haug, Sonja T1 - Acceptance of Telepresence Robotics, Telecare and Teletherapy Among Stroke Patients, Relatives and Therapy Staff T2 - dHealth 2024: proceedings of the 18th annual conference on Health Informatics meets Digital Health conference N2 - Background: Stroke as a cause of disability in adulthood causes an increasing demand for therapy and care services, including telecare and teletherapy. Objectives: Aim of the study is to analyse the acceptance of telepresence robotics and digital therapy applications. Methods: Longitudinal study with a before and after survey of patients, relatives and care and therapy staff. Results: Acceptance of the technology analysed is high in all three groups. Although acceptance among patients declined in parts of the cases in the second survey after having used telerobotics, all in all approval ratings remained high. With regard to patients no significant correlation was found between the general technology acceptance and the acceptance of use of telerobotics. Conclusion: Accepted new telecare and teletherapies can be offered with the help of telepresence robotics. This requires knowledge of and experience with the technology. Y1 - 2024 SN - 978-1-64368-517-5 U6 - https://doi.org/10.3233/SHTI240005 SN - 0926-9630 N1 - Corresponding Author: Edda Currle SP - 15 EP - 21 PB - IOS Press ER - TY - JOUR A1 - Göppel, Simon A1 - Frikel, Jürgen A1 - Haltmeier, Markus T1 - Data-Proximal Complementary ℓ1-TV Reconstruction for Limited Data Computed Tomography JF - Mathematics N2 - 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. KW - image reconstruction KW - limited data KW - artifact reduction KW - sparse regularization KW - total variation KW - wedge-adapted curvelets Y1 - 2024 U6 - https://doi.org/10.3390/math12101606 SN - 2227-7390 N1 - Corresponding author der OTH Regensburg: Jürgen Frikel (und Markus Haltmeier) VL - 12 IS - 10 PB - MDPI ER - TY - JOUR A1 - Romano, Marco A1 - Ehrlich, Ingo T1 - Classification of damping properties of fabric-reinforced flat beam-like specimens by a degree of ondulation implying a mesomechanic kinematic JF - Science and Engineering of Composite Materials N2 - 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. KW - fiber-reinforced plastics KW - mesomechanic scale KW - fabric-reinforced layer KW - ondulation Y1 - 2024 U6 - https://doi.org/10.1515/secm-2024-0019 SN - 2191-0359 SN - 0792-1233 N1 - Corresponding author der OTH Regensburg: Marco Romano VL - 31 IS - 1 PB - Walter de Gruyter GmbH 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 - Glavan, Gašper A1 - Belyaeva, Inna A. A1 - Shamonin (Chamonine), Mikhail T1 - On the Piezomagnetism of Magnetoactive Elastomeric Cylinders in Uniform Magnetic Fields: Height Modulation in the Vicinity of an Operating Point by Time-Harmonic Fields JF - Polymers N2 - 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. Y1 - 2024 U6 - https://doi.org/10.3390/polym16192706 N1 - Corresponding author der OTH Regensburg: Gašper Glavan VL - 16 IS - 19 ER - TY - JOUR A1 - Siegl, Marco A1 - Jungbauer, Bastian A1 - Gebhardt, Jakob A1 - Judenmann, Anna A1 - Ehrlich, Ingo ED - Baeten, Somayeh T1 - Winding process of fibre-reinforced thermoplastic tubes with integrated tape production through in-situ roving impregnation and infrared consolidation JF - The International Journal of Advanced Manufacturing Technology N2 - 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. KW - Thermoplastic composite tubes KW - Filament-winding KW - Tape production KW - Thermoplastic impregnation KW - In-situ roving impregnation KW - Infrared consolidation Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-77827 N1 - Corresponding author der OTH Regensburg: Marco Siegl VL - 135 IS - 5-6 SP - 2847 EP - 2870 PB - Springer Nature ER - TY - JOUR A1 - Franke, Markus A1 - Wagner, Marcus T1 - Transient surrogate modeling of modally reduced structures with discontinuous loads and damping JF - Archive of Applied Mechanics N2 - 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. KW - Discontinuous loads KW - Modal decomposition KW - Surrogate modeling KW - Long short-term memory KW - Finite element method Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-72834 N1 - Corresponding author der OTH Regensburg: Markus Franke VL - 94 IS - 5 PB - Springer Nature ER - TY - JOUR A1 - Schuhegger, Lukas A1 - Kara, Sinan A1 - Galka, Stefan A1 - Dünnweber, Jan A1 - Meißner, Sebastian T1 - Umzugsplanung mit Fabrikdatenmodellen und Virtual Reality JF - Zeitschrift für wirtschaftlichen Fabrikbetrieb N2 - Angesichts eines dynamischen industriellen Umfelds müssen produzierende Unternehmen flexibel bleiben und sich kontinuierlich anpassen, um ihre Wettbewerbsfähigkeit zu erhalten. Eine effektive Planung von Restrukturierungen in Produktionssystemen, oft als Umzugsplanung bezeichnet, ist entscheidend, um Verzögerungen zu vermeiden und Stillstandszeiten zu minimieren. Die Identifikation von Umzugsfällen, welche den Umfang umzuziehender Ressourcen wie Maschinen, Anlagen, Ausrüstungen und Arbeitsplätzen beschreiben und die Definition zugehöriger Aufgaben sind essenzielle Schritte der Umzugsplanung. Dieser Beitrag stellt eine Vorgehensweise zur Bestimmung von Umzugsfällen mittels eines Fabrikdatenmodells vor, ergänzt durch eine Visualisierung in Virtual Reality, um Planende bei der Umzugsplanung zu unterstützen. N2 - Given a dynamic industrial environment, manufacturing companies must remain flexible and continuously adapt to maintain their competitiveness. Effective planning of restructuring efforts in production systems, often referred to as reconfiguration planning, is crucial to avoid delays and minimize downtime. Identifying reconfiguration cases, which describe the scope of resources to be relocated, such as machines, equipment, and workstations, and defining the associated tasks are essential steps in reconfiguration planning. This paper presents an approach for determining reconfiguration cases using a factory data model, complemented by visualization in virtual reality, to support planners in the reconfiguration process. KW - Fabrikdatenmodel KW - Virtual Reality KW - Umzugsplanung KW - Restrukturierung KW - Umstellung KW - Factory Data Model KW - Reconfiguration Planning KW - Restructuring KW - Relocation KW - Virtual Reality Y1 - 2024 U6 - https://doi.org/10.1515/zwf-2024-1154 SN - 2511-0896 SN - 0947-0085 N1 - Corresponding author der OTH Regensburg: Lukas Schuhegger VL - 119 IS - 11 SP - 799 EP - 804 PB - de Gruyter ER - TY - JOUR A1 - Schmidbauer, Simon A1 - Becker, Maria A1 - Haug, Sonja T1 - Online Political Participation of Refugees in Germany: Analysis of a Survey in Bavaria JF - Sage Online N2 - 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. KW - political participation KW - internet use KW - refugees KW - political online participation Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-77671 N1 - Corresponding author der OTH Regensburg: Sonja Haug PB - Sage CY - Thousand Oaks ER - TY - JOUR A1 - Grad, Marius A1 - Schultheiß, Ulrich A1 - Diemar, Andreas A1 - Spieß, Lothar A1 - Noster, Ulf T1 - Preparation methodology for the microstructural characterization of diffusion layers in a titanium/steel composite JF - Practical Metallography N2 - 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. N2 - Beim Heißpressen von Titan und Kohlenstoffstahl entsteht an der Grenzfläche eine Diffusionsschicht, welche abhängig vom Kohlenstoffgehalt des verwendeten Stahls entweder ausschließlich TiC oder zusätzliche andere Phasen enthält. Im Fall eines Stahls mit mittlerer Kohlenstoffkonzentration (0,67 wt.-% C) bildet sich eine reine TiC-Schicht. Um eine Aussage über die funktionalen und mikrostrukturellen Eigenschaften, wie Schichtdicke, Porosität oder Korngröße, entsprechender Schichten treffen zu können, wurde eine Präparationsmethodik entwickelt. Hierbei wird jedoch nicht nur das Gefüge der Diffusionsschicht, sondern auch das der beiden Grundsubstrate entwickelt. Ein Vergleich mit Elektronenrückstreubeugungs-Untersuchungen (EBSD) liefert hinsichtlich der Mikrostruktur vergleichbare Ergebnisse. Auch die Messung der Elementverteilung durch Glimmentladungsspektroskopie (GDOES) kann durch eine Schliffbildanalyse unter Anwendung der neuen Präparationsmethodik belegt werden. Die Methodik stellt also eine Möglichkeit zur schnellen und sicheren Kontrolle der Schichtbildung beim Heißpressen von Titan und Kohlenstoffstahl dar. T2 - Präparationsmethodik zur mikrostrukturellen Charakterisierung von Diffusionsschichten eines Titan-Stahl-Verbunds KW - Diffusion layers KW - TiC KW - microstructure KW - preparation methodology KW - EBSD KW - GDOES Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-78346 SN - 2195-8599 N1 - Corresponding author der OTH Regensburg: Marius Grad VL - 61 IS - 12 SP - 938 EP - 946 PB - Walter de Gruyter GmbH ER - TY - JOUR A1 - Knödler, Leonard A1 - Dean, Jillian A1 - Knoedler, Samuel A1 - Kauke-Navarro, Martin A1 - Hollmann, Katharina A1 - Alfertshofer, Michael A1 - Helm, Sabrina A1 - Prantl, Lukas A1 - Schliermann, Rainer T1 - Hard shell, soft core? Multi-disciplinary and multi-national insights into mental toughness among surgeons JF - Frontiers in Surgery N2 - Background: With the prevalence of burnout among surgeons posing a significant threat to healthcare outcomes, the mental toughness of medical professionals has come to the fore. Mental toughness is pivotal for surgical performance and patient safety, yet research into its dynamics within a global and multi-specialty context remains scarce. This study aims to elucidate the factors contributing to mental toughness among surgeons and to understand how it correlates with surgical outcomes and personal well-being. Methods: Utilizing a cross-sectional design, this study surveyed 104 surgeons from English and German-speaking countries using the Mental Toughness Questionnaire (MTQ-18) along with additional queries about their surgical practice and general life satisfaction. Descriptive and inferential statistical analyses were applied to investigate the variations in mental toughness across different surgical domains and its correlation with professional and personal factors. Results: The study found a statistically significant higher level of mental toughness in micro-surgeons compared to macro-surgeons and a positive correlation between mental toughness and surgeons' intent to continue their careers. A strong association was also observed between general life satisfaction and mental toughness. No significant correlations were found between the application of psychological skills and mental toughness. Conclusion: Mental toughness varies significantly among surgeons from different specialties and is influenced by professional dedication and personal life satisfaction. These findings suggest the need for targeted interventions to foster mental toughness in the surgical community, potentially enhancing surgical performance and reducing burnout. Future research should continue to explore these correlations, with an emphasis on longitudinal data and the development of resilience-building programs. KW - mental toughness KW - mental health KW - resilience KW - robustness KW - psychology KW - surgery Y1 - 2024 U6 - https://doi.org/10.3389/fsurg.2024.1361406 N1 - Correspondign author der OTH Regensburg: Rainer Schliermann (und Leonard Knoedler) VL - 11 PB - Frontiers ER - TY - JOUR A1 - Schulz, Carsten A1 - Vogl, Yannick A1 - Geiger, Benjamin A1 - Schaeffer, Thomas T1 - Vor- und Nachteile einer Lumped-Mass-Modellierung von Förderbändern am Beispiel eines Zwei-Walzensystems JF - Forschung im Ingenieurwesen JF - Engineering Research N2 - Im Betrieb von Förderbändern auftretende Phänomene sind das Bandwandern in Achsrichtung der Walzen und die Bandverformung in der Bandebene [1, S. 142]. Das Bandwandern ist bisher detailliert untersucht [2–4], während die Bandverformung Gegenstand weniger Veröffentlichungen ist. Deshalb wird in diesem Artikel eine Methode zur Berechnung der sich im dynamischen Betrieb einstellenden Verformung eines elastischen Förderbandes vorgestellt. Dazu wird ein Mehrkörpersimulations-Modell basierend auf der Lumped-Mass-Modellierung verwendet. Als Untersuchungsbeispiel dient ein Zwei-Walzensystem mit flexiblen und zylindrischen Walzen, sowie ein flexibles Förderband. Es zeigt sich, dass mit der Lumped-Mass-Modellierung eine dynamische Bandverformung, die von der gewählten Diskretisierung abhängt, berechnet werden kann. Aufgrund dieser Abhängigkeit ist es notwendig eine Konvergenzanalyse durchzuführen. Zusätzlich ist darauf zu achten, dass die künstliche Anregung aufgrund der Lumped-Mass-Modellierung nicht mit einer Eigenfrequenz des Modells zusammenfällt. N2 - Phenomena occurring in the operation of conveyor belts are belt walking in the axial direction of the rollers and belt deformation in the belt plane [1, S. 142]. Whereas [2,3,4] investigate the first effect in detail [2,3,4], the latter is mostly neglected. The authors therefore focus on the calculation of the deformation of the elastic conveyor belt during dynamic operation using a flexible multibody approach. To consider the flexibility of the belt in an efficient way, the model uses the well-known Lumped-Mass-Approach. The discretization of the model (number and distance of masses) thereby impacts the shape of the band deformation. The article investigates the minimum required discretization for two dimensions, the effect on the system response and the influence on the computation time. As an example, a two-roller system with flexible, cylindrical rolls and a flexible conveyor belt is used. The results of the model will be compared with theoretical expectations and show very promising results. T2 - Pros and cons of Lumped Mass Modelling of conveyor belts using a two-roller system Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-72891 SN - 0015-7899 N1 - Corresponding author der OTH Regensburg: Carsten Schulz VL - 88 IS - 1 PB - Springer Vieweg CY - Belrin ; Heidelberg ER - TY - JOUR A1 - Schuderer, Matthias A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Schulz, Carsten T1 - Friction modeling from a practical point of view JF - Multibody System Dynamics N2 - AbstractRegularized static friction models have been used successfully for many years. However, they are unable to maintain static friction in detail. For this reason, dynamic friction models have been developed and published in the literature. However, commercial multibody simulation packages such as Adams, RecurDyn, and Simpack have developed their own specific stick-slip models instead of adopting one of the public domain approaches. This article introduces the fundamentals of these commercial models and their behavior from a practical point of view. The stick-slip models were applied to a simple test model and a more sophisticated model of a festoon cable system using their standard parameters. KW - Multibody dynamics KW - Friction KW - Stick-slip effect KW - Adams KW - RecurDyn KW - Simpack Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-72513 SN - 1384-5640 N1 - Corresponding author: Matthias Schuderer PB - Springernature ER - TY - JOUR A1 - Markov-Glazer, Alon A1 - Elbe, Anne-Marie A1 - Schliermann, Rainer T1 - The use of psychological skills in deaflympic sport JF - European Journal of Adapted Physical Activity N2 - This study explores the use of psychological skills among Deaflympic athletes and aims to provide initial insights into sport psychology practices in this overlooked population. To this end, the frequency of psychological skills’ usage, usage patterns, and differences between subgroups were examined within this population. The Test of Performance Strategies (TOPS) was administered to 84 German Deaflympic athletes (mean age = 28; 27% female) along with biographical questions (e.g., hearing status). The findings indicate that Deaflympic athletes regularly utilize psychological skills in training and competition, displaying similar usage to that of Olympic athletes. However, only a minority of Deaflympic athletes train their skills with professional consultants. Additionally, relaxation techniques were employed rarely in comparison to the other investigated skills. This study’s findings contribute to the foundation of sport psychology research with Deaflympic athletes and underscore the need for a differentiated approach in tailoring interventions for this population. KW - Deaf culture KW - Deaflympian KW - psychological skills training KW - TOPS Y1 - 2024 U6 - https://doi.org/10.5507/euj.2024.012 VL - 17 IS - 15 PB - European Federation of Adapted Physical Activity CY - Olomouc ER - TY - JOUR A1 - Rückert, Tobias A1 - Rückert, Daniel A1 - Palm, Christoph T1 - Methods and datasets for segmentation of minimally invasive surgical instruments in endoscopic images and videos: A review of the state of the art JF - Computers in Biology and Medicine N2 - In the field of computer- and robot-assisted minimally invasive surgery, enormous progress has been made in recent years based on the recognition of surgical instruments in endoscopic images and videos. In particular, the determination of the position and type of instruments is of great interest. Current work involves both spatial and temporal information, with the idea that predicting the movement of surgical tools over time may improve the quality of the final segmentations. The provision of publicly available datasets has recently encouraged the development of new methods, mainly based on deep learning. In this review, we identify and characterize datasets used for method development and evaluation and quantify their frequency of use in the literature. We further present an overview of the current state of research regarding the segmentation and tracking of minimally invasive surgical instruments in endoscopic images and videos. The paper focuses on methods that work purely visually, without markers of any kind attached to the instruments, considering both single-frame semantic and instance segmentation approaches, as well as those that incorporate temporal information. The publications analyzed were identified through the platforms Google Scholar, Web of Science, and PubMed. The search terms used were “instrument segmentation”, “instrument tracking”, “surgical tool segmentation”, and “surgical tool tracking”, resulting in a total of 741 articles published between 01/2015 and 07/2023, of which 123 were included using systematic selection criteria. A discussion of the reviewed literature is provided, highlighting existing shortcomings and emphasizing the available potential for future developments. KW - Deep Learning KW - Minimal-invasive Chirurgie KW - Bildsegmentierung KW - Surgical instrument segmentation KW - Surgical instrument tracking KW - Spatio-temporal information KW - Endoscopic surgery KW - Robot-assisted surgery Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-69830 N1 - Corresponding author: Tobias Rückert N1 - Corrigendum unter: https://opus4.kobv.de/opus4-oth-regensburg/frontdoor/index/index/docId/7033 VL - 169 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hantsch, Carolin A1 - Westner, Markus A1 - Matschi, Markus T1 - IT/OT-Konvergenz: Status-Quo und Umsetzungsempfehlungen JF - HMD Praxis der Wirtschaftsinformatik N2 - Organisationen machen große Anstrengungen zur Verbesserung ihrer Ambidextrie, d. h. ihrer Fähigkeit sowohl Exploitationsziele (z. B. Effizienz, Vorhersagbarkeit) als auch Explorationsziele (z. B. Anpassbarkeit, Innovation) zu erreichen. Obwohl gemäß der Praxisliteratur Technologie in Software-Projekten dabei eine zentrale Rolle spielen kann, gibt es kaum Forschung dazu, wie technologische Faktoren Ambidexterie in Software-Projekten beeinflussen. In dieser Studie untersuchen wir die Rolle dreier technologischer Faktoren: kontinuierliche Integration, Standardisierung und Microservice-Architektur. Die Ergebnisse einer Mehrinformanten-Umfrage in 95 Projekten in der Schweiz und Dänemark zeigen, dass kontinuierliche Integration und Standardisierung mit höherer Ambidexterie einhergehen, während der Zusammenhang zwischen Microservice-Architektur und Ambidextrie nicht signifikant ist. Unser Artikel geht über die existierende Forschung hinaus, indem er zeigt, dass kontinuierliche Integration und Standardisierung nicht nur Exploitation, sondern auch Exploration fördern können. Wir diskutieren auch Gründe für den insignifikanten Zusammenhang zwischen Microservice-Architektur und Ambidextrie. N2 - This study examines IT/OT Convergence in 31 predominantly large German companies. It presents an “IT/OT Governance Framework” as a specific model for successful convergence implementation. The analysis reveals a heterogeneous level of convergence maturity across the examined companies, the majority of which are at the beginning or in the implementation phase. Close cooperation between IT and OT is favored, but without IT completely taking over OT. An IT/OT tandem consisting of a CIO and a central OT responsible person is seen as the ideal way to take responsibility. Six specific recommendations were derived from the interviews and included in the IT/OT Governance Framework developed. These include ensuring top management support, using security as a driver, introducing a central OT responsible person, bringing IT and OT teams physically closer together, continuously demonstrating the added value of convergence, and taking a step-by-step approach to implementation. KW - IT/OT Convergence KW - Operational Technology KW - OT KW - Governance Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-77937 N1 - Corresponding author der OTH Regensburg: Markus Westner PB - Springer Nature ER - TY - JOUR A1 - Glavan, Gašper A1 - Belyaeva, Inna A. A1 - Shamonin (Chamonine), Mikhail T1 - Transient Response of Macroscopic Deformation of Magnetoactive Elastomeric Cylinders in Uniform Magnetic Fields JF - Polymers N2 - Significant deformations of bodies made from compliant magnetoactive elastomers (MAE) in magnetic fields make these materials promising for applications in magnetically controlled actuators for soft robotics. Reported experimental research in this context was devoted to the behaviour in the quasi-static magnetic field, but the transient dynamics are of great practical importance. This paper presents an experimental study of the transient response of apparent longitudinal and transverse strains of a family of isotropic and anisotropic MAE cylinders with six different aspect ratios in time-varying uniform magnetic fields. The time dependence of the magnetic field has a trapezoidal form, where the rate of both legs is varied between 52 and 757 kA/(s·m) and the maximum magnetic field takes three values between 153 and 505 kA/m. It is proposed to introduce four characteristic times: two for the delay of the transient response during increasing and decreasing magnetic field, as well as two for rise and fall times. To facilitate the comparison between different magnetic field rates, these characteristic times are further normalized on the rise time of the magnetic field ramp. The dependence of the normalized characteristic times on the aspect ratio, the magnetic field slew rate, maximum magnetic field values, initial internal structure (isotropic versus anisotropic specimens) and weight fraction of the soft-magnetic filler are obtained and discussed in detail. The normalized magnetostrictive hysteresis loop is introduced, and used to explain why the normalized delay times vary with changing experimental parameters. KW - magnetoactive elastomer KW - magnetorheological elastomer KW - macroscopic deformation KW - magnetostriction KW - time-varying magnetic field Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-71067 SN - 2073-4360 N1 - Corresponding author der OTH Regensburg: Gašper Glavan Zugehöriges Datenset: doi:10.5281/zenodo.10679499 VL - 16 IS - 5, Special Issue Magnetic Polymer Composites: Design and Application II PB - MDPI CY - Basel, Schweiz ER - TY - JOUR A1 - Weindler, Jeremy A1 - Dawoud, Belal T1 - Experimental investigation of a small-scale continuous flow ohmic heating reactor for a highly effective conversion of renewable electricity surpluses into heat JF - Applied Thermal Engineering N2 - Sector coupling is expected to play a decisive role as a key technology to realize the energy transition towards green energy supply. This work introduces, therefore, a comprehensive experimental study on a new power-to-heat system based on the continuous-flow, ohmic heating principle, which aims at utilizing renewable electricity in green processes. The ohmic heating technology, which is widely applied in the food industry, has been adapted and evaluated for delivering heat and domestic hot water to a single-family house. The introduced prototype is designed to convert renewable electricity into heat in the power range between 1000 and 3000 W with a typical electrical household installation (230 V, 50 Hz and 16 A fuse). A dedicated test rig has been developed and a comprehensive experimental campaign has been carried out to investigate the performance of the introduced system under typical operating conditions of a single-family house. Both the conversion efficiency and the dynamics of the thermal response of the introduced system have been assessed. It turned out that, the temperature lift between the return and supply of the reactor, and consequently, the conversion efficiency of electrical into thermal energy, are independent on the return temperature, for a fixed value of the volume flow rate of the electrolyte solution. A remarkable steady-state conversion efficiency of 97.5% has been measured. In addition, the dynamic response of the ohmic heating system has been found to be strongly dependent on the desired temperature lift. By an implemented controller, 95% of the steady state temperature lift of 44.5 K can be realized in 50 s, which marks an exceptionally rapid thermal response. The obtained results pave the way towards a field test study of the developed technology in a real household installation as well as to extend the focus on new fields such as green chemical processes. KW - renewable energy KW - Ohmic-heating KW - Power-to-heat KW - Sector coupling KW - Energy surpluses Y1 - 2024 U6 - https://doi.org/10.1016/j.applthermaleng.2024.122401 SN - 1359-4311 N1 - Corresponding author der OTH Regensburg: Dawoud, Belal VL - 242 PB - Elsevier ER -