Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Bemerkung Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Zugriffsart Link Abteilungen OPUS4-11083 Wissenschaftlicher Artikel Zhen, Manghao, ; Liang, Yunpei, ; Staat, Manfred, m.staat@fh-aachen.de; Li, Quanqui, ; Li, Jianbo, Discontinuous fracture behaviors and constitutive model of sandstone specimens containing non-parallel prefabricated fissures under uniaxial compression The deformation and damage laws of non-homogeneous irregular structural planes in rocks are the basis for studying the stability of rock engineering. To investigate the damage characteristics of rock containing non-parallel fissures, uniaxial compression tests and numerical simulations were conducted on sandstone specimens containing three non-parallel fissures inclined at 0°, 45° and 90° in this study. The characteristics of crack initiation and crack evolution of fissures with different inclinations were analyzed. A constitutive model for the discontinuous fractures of fissured sandstone was proposed. The results show that the fracture behaviors of fissured sandstone specimens are discontinuous. The stress-strain curves are non-smooth and can be divided into nonlinear crack closure stage, linear elastic stage, plastic stage and brittle failure stage, of which the plastic stage contains discontinuous stress drops. During the uniaxial compression test, the middle or ends of 0° fissures were the first to crack compared to 45° and 90° fissures. The end with small distance between 0° and 45° fissures cracked first, and the end with large distance cracked later. After the final failure, 0° fissures in all specimens were fractured, while 45° and 90° fissures were not necessarily fractured. Numerical simulation results show that the concentration of compressive stress at the tips of 0°, 45° and 90° fissures, as well as the concentration of tensile stress on both sides, decreased with the increase of the inclination angle. A constitutive model for the discontinuous fractures of fissured sandstone specimens was derived by combining the logistic model and damage mechanic theory. This model can well describe the discontinuous drops of stress and agrees well with the whole processes of the stress-strain curves of the fissured sandstone specimens. Amsterdam Elsevier 2024 13 Seiten Theoretical and Applied Fracture Mechanics 131 Art. No. 104373 10.1016/j.tafmec.2024.104373 campus https://doi.org/10.1016/j.tafmec.2024.104373 Fachbereich Medizintechnik und Technomathematik OPUS4-11082 Wissenschaftlicher Artikel Engelmann, Ulrich M., engelmann@fh-aachen.de; Simsek, Beril, ; Shalaby, Ahmed, ; Krause, Hans-Joachim, h.krause@fh-aachen.de Key contributors to signal generation in frequency mixing magnetic detection (FMMD): an in silico study Frequency mixing magnetic detection (FMMD) is a sensitive and selective technique to detect magnetic nanoparticles (MNPs) serving as probes for binding biological targets. Its principle relies on the nonlinear magnetic relaxation dynamics of a particle ensemble interacting with a dual frequency external magnetic field. In order to increase its sensitivity, lower its limit of detection and overall improve its applicability in biosensing, matching combinations of external field parameters and internal particle properties are being sought to advance FMMD. In this study, we systematically probe the aforementioned interaction with coupled Néel-Brownian dynamic relaxation simulations to examine how key MNP properties as well as applied field parameters affect the frequency mixing signal generation. It is found that the core size of MNPs dominates their nonlinear magnetic response, with the strongest contributions from the largest particles. The drive field amplitude dominates the shape of the field-dependent response, whereas effective anisotropy and hydrodynamic size of the particles only weakly influence the signal generation in FMMD. For tailoring the MNP properties and parameters of the setup towards optimal FMMD signal generation, our findings suggest choosing large particles of core sizes dc > 25 nm nm with narrow size distributions (σ < 0.1) to minimize the required drive field amplitude. This allows potential improvements of FMMD as a stand-alone application, as well as advances in magnetic particle imaging, hyperthermia and magnetic immunoassays. Basel MDPI 2024 Artikel 1945 Sensors 24 This article belongs to the Special Issue "Advances in Magnetic Sensors and Their Applications" 6 10.3390/s24061945 weltweit https://doi.org/10.3390/s24061945 Fachbereich Medizintechnik und Technomathematik OPUS4-11081 Buch (Monographie) Elsaesser, Evelyn, ; Klebinggat, Michael, ; Kuhn, Wilfried, ; Michielsens, Constant, ; Pauels, Willibert, ; Popkes, Enno E., ; Schneider, Elke, ; Laack, Walter van, Dr.vanLaack@web.de; Warven, Rinus van, Laack, Walter van Schnittstelle Tod - Ist die Menschheit zu retten ohne Vertrauen auf ein Danach Aachen van Laack Buchverlag 2024 156 Seiten 978-3-936624-58-8 8. Tagungsband zum NTE-Seminar in Aachen am, 11.11.2023 https://www.vanlaack-buch.de/buecher-d/schnittstelle-tod-ist-die-menschheit-zu-retten-ohne-vertrauen-auf-ein-danach/ Fachbereich Medizintechnik und Technomathematik OPUS4-11068 unpublished Grieger, Niklas, grieger@fh-aachen.de; Mehrkanoon, Siamak, ; Bialonski, Stephan, bialonski@fh-aachen.de Preprint: Data-efficient sleep staging with synthetic time series pretraining Analyzing electroencephalographic (EEG) time series can be challenging, especially with deep neural networks, due to the large variability among human subjects and often small datasets. To address these challenges, various strategies, such as self-supervised learning, have been suggested, but they typically rely on extensive empirical datasets. Inspired by recent advances in computer vision, we propose a pretraining task termed "frequency pretraining" to pretrain a neural network for sleep staging by predicting the frequency content of randomly generated synthetic time series. Our experiments demonstrate that our method surpasses fully supervised learning in scenarios with limited data and few subjects, and matches its performance in regimes with many subjects. Furthermore, our results underline the relevance of frequency information for sleep stage scoring, while also demonstrating that deep neural networks utilize information beyond frequencies to enhance sleep staging performance, which is consistent with previous research. We anticipate that our approach will be advantageous across a broad spectrum of applications where EEG data is limited or derived from a small number of subjects, including the domain of brain-computer interfaces. 2024 10 Seiten arXiv weltweit https://arxiv.org/abs/2403.08592 Fachbereich Medizintechnik und Technomathematik OPUS4-11053 Wissenschaftlicher Artikel Bornheim, Tobias, ; Grieger, Niklas, ; Blaneck, Patrick Gustav, ; Bialonski, Stephan, bialonski@fh-aachen.de Speaker Attribution in German Parliamentary Debates with QLoRA-adapted Large Language Models The growing body of political texts opens up new opportunities for rich insights into political dynamics and ideologies but also increases the workload for manual analysis. Automated speaker attribution, which detects who said what to whom in a speech event and is closely related to semantic role labeling, is an important processing step for computational text analysis. We study the potential of the large language model family Llama 2 to automate speaker attribution in German parliamentary debates from 2017-2021. We fine-tune Llama 2 with QLoRA, an efficient training strategy, and observe our approach to achieve competitive performance in the GermEval 2023 Shared Task On Speaker Attribution in German News Articles and Parliamentary Debates. Our results shed light on the capabilities of large language models in automating speaker attribution, revealing a promising avenue for computational analysis of political discourse and the development of semantic role labeling systems. Regensburg Gesellschaft für Sprachtechnologie und Computerlinguistik 2024 13 Seiten Journal for language technology and computational linguistics : JLCL 37 1 10.21248/jlcl.37.2024.244 weltweit https://doi.org/10.21248/jlcl.37.2024.244 Fachbereich Medizintechnik und Technomathematik OPUS4-11043 Wissenschaftlicher Artikel Schoenrock, Britt, ; Muckelt, Paul E., ; Hastermann, Maria, ; Albracht, Kirsten, albracht@fh-aachen.de; MacGregor, Robert, ; Martin, David, ; Gunga, Hans-Christian, ; Salanova, Michele, ; Stokes, Maria J., ; Warner, Martin B., ; Blottner, Dieter, Muscle stiffness indicating mission crew health in space Muscle function is compromised by gravitational unloading in space affecting overall musculoskeletal health. Astronauts perform daily exercise programmes to mitigate these effects but knowing which muscles to target would optimise effectiveness. Accurate inflight assessment to inform exercise programmes is critical due to lack of technologies suitable for spaceflight. Changes in mechanical properties indicate muscle health status and can be measured rapidly and non-invasively using novel technology. A hand-held MyotonPRO device enabled monitoring of muscle health for the first time in spaceflight (> 180 days). Greater/maintained stiffness indicated countermeasures were effective. Tissue stiffness was preserved in the majority of muscles (neck, shoulder, back, thigh) but Tibialis Anterior (foot lever muscle) stiffness decreased inflight vs. preflight (p < 0.0001; mean difference 149 N/m) in all 12 crewmembers. The calf muscles showed opposing effects, Gastrocnemius increasing in stiffness Soleus decreasing. Selective stiffness decrements indicate lack of preservation despite daily inflight countermeasures. This calls for more targeted exercises for lower leg muscles with vital roles as ankle joint stabilizers and in gait. Muscle stiffness is a digital biomarker for risk monitoring during future planetary explorations (Moon, Mars), for healthcare management in challenging environments or clinical disorders in people on Earth, to enable effective tailored exercise programmes. London Springer Nature 2024 13 Seiten Scientific Reports 14 Corresponding author: Dieter Blottner Article number: 4196 10.1038/s41598-024-54759-6 weltweit https://doi.org/10.1038/s41598-024-54759-6 Fachbereich Medizintechnik und Technomathematik OPUS4-11038 Teil eines Buches Kraft, Bodo, kraft@fh-aachen.de; Kohl, Philipp, p.kohl@fh-aachen.de; Meinecke, Matthias, meinecke@fh-aachen.de Bernert, Christian; Scheurer, Steffen; Wehnes, Harald Analyse und Nachverfolgung von Projektzielen durch Einsatz von Natural Language Processing UVK Verlag 2024 10 KI in der Projektwirtschaft : was verändert sich durch KI im Projektmanagement? 978-3-3811-1132-9 (Online) 157 167 10.24053/9783381111329 bezahl https://doi.org/10.24053/9783381111329 Fachbereich Medizintechnik und Technomathematik OPUS4-10891 Wissenschaftlicher Artikel Uysal, Karya, uysal@fh-aachen.de; Firat, Ipek Serat, firat@fh-aachen.de; Creutz, Till, till.creutz@fh-aachen.de; Aydin, Inci Cansu, ; Artmann, Gerhard, artmann@fh-aachen.de; Teusch, Nicole, ; Temiz Artmann, Aysegül, a.artmann@fh-aachen.de A novel in vitro wound healing assay using free-standing, ultra-thin PDMS membranes Advances in polymer science have significantly increased polymer applications in life sciences. We report the use of free-standing, ultra-thin polydimethylsiloxane (PDMS) membranes, called CellDrum, as cell culture substrates for an in vitro wound model. Dermal fibroblast monolayers from 28- and 88-year-old donors were cultured on CellDrums. By using stainless steel balls, circular cell-free areas were created in the cell layer (wounding). Sinusoidal strain of 1 Hz, 5% strain, was applied to membranes for 30 min in 4 sessions. The gap circumference and closure rate of un-stretched samples (controls) and stretched samples were monitored over 4 days to investigate the effects of donor age and mechanical strain on wound closure. A significant decrease in gap circumference and an increase in gap closure rate were observed in trained samples from younger donors and control samples from older donors. In contrast, a significant decrease in gap closure rate and an increase in wound circumference were observed in the trained samples from older donors. Through these results, we propose the model of a cell monolayer on stretchable CellDrums as a practical tool for wound healing research. The combination of biomechanical cell loading in conjunction with analyses such as gene/protein expression seems promising beyond the scope published here. Basel MDPI 2022 Artikel 22 membranes 2023 This article belongs to the Special Issue "Latest Scientific Discoveries in Polymer Membranes" 13(1) 10.3390/membranes13010022 weltweit https://doi.org/10.3390/membranes13010022 Fachbereich Medizintechnik und Technomathematik OPUS4-11006 Konferenzveröffentlichung Schmitz, Annika, ; Apandi, Shah Eiman Amzar Shah, ; Spillner, Jan, ; Hima, Flutura, ; Behbahani, Mehdi, behbahani@fh-aachen.de Digel, Ilya; Staat, Manfred; Trzewik, Jürgen; Sielemann, Stefanie; Erni, Daniel; Zylka, Waldemar Effect of different cannula positions in the pulmonary artery on blood flow and gas exchange using computational fluid dynamics analysis Pulmonary arterial cannulation is a common and effective method for percutaneous mechanical circulatory support for concurrent right heart and respiratory failure [1]. However, limited data exists to what effect the positioning of the cannula has on the oxygen perfusion throughout the pulmonary artery (PA). This study aims to evaluate, using computational fluid dynamics (CFD), the effect of different cannula positions in the PA with respect to the oxygenation of the different branching vessels in order for an optimal cannula position to be determined. The four chosen different positions (see Fig. 1) of the cannulas are, in the lower part of the main pulmonary artery (MPA), in the MPA at the junction between the right pulmonary artery (RPA) and the left pulmonary artery (LPA), in the RPA at the first branch of the RPA and in the LPA at the first branch of the LPA. Duisburg Universität Duisburg-Essen 2024 1 4th YRA MedTech Symposium 2024 : February 1 / 2024 / FH Aachen 978-3-940402-65-3 29 30 10.17185/duepublico/81475 weltweit https://doi.org/10.17185/duepublico/81475 Fachbereich Medizintechnik und Technomathematik OPUS4-11005 Konferenzveröffentlichung Simsek, Beril, ; Krause, Hans-Joachim, h.krause@fh-aachen.de; Engelmann, Ulrich M., engelmann@fh-aachen.de Digel, Ilya; Staat, Manfred; Trzewik, Jürgen; Sielemann, Stefanie; Erni, Daniel; Zylka, Waldemar Magnetic biosensing with magnetic nanoparticles: Simulative approach to predict signal intensity in frequency mixing magnetic detection Magnetic nanoparticles (MNP) are investigated with great interest for biomedical applications in diagnostics (e.g. imaging: magnetic particle imaging (MPI)), therapeutics (e.g. hyperthermia: magnetic fluid hyperthermia (MFH)) and multi-purpose biosensing (e.g. magnetic immunoassays (MIA)). What all of these applications have in common is that they are based on the unique magnetic relaxation mechanisms of MNP in an alternating magnetic field (AMF). While MFH and MPI are currently the most prominent examples of biomedical applications, here we present results on the relatively new biosensing application of frequency mixing magnetic detection (FMMD) from a simulation perspective. In general, we ask how the key parameters of MNP (core size and magnetic anisotropy) affect the FMMD signal: by varying the core size, we investigate the effect of the magnetic volume per MNP; and by changing the effective magnetic anisotropy, we study the MNPs' flexibility to leave its preferred magnetization direction. From this, we predict the most effective combination of MNP core size and magnetic anisotropy for maximum signal generation. Duisburg Universität Duisburg-Essen 2024 1 4th YRA MedTech Symposium 2024 : February 1 / 2024 / FH Aachen 978-3-940402-65-3 27 28 10.17185/duepublico/81475 weltweit https://doi.org/10.17185/duepublico/81475 Fachbereich Medizintechnik und Technomathematik OPUS4-11004 Buch (Monographie) Staat, Manfred, m.staat@fh-aachen.de; Digel, Ilya, digel@fh-aachen.de; Trzewik, Jürgen, ; Sielemann, Stefanie, ; Erni, Daniel, ; Zylka, Waldemar, Symposium Proceedings; 4th YRA MedTech Symposium 2024 : February 1 / 2024 / FH Aachen Duisburg Universität Duisburg-Essen 2024 40 Seiten 978-3-940402-65-3 10.17185/duepublico/81475 weltweit https://doi.org/10.17185/duepublico/81475 Fachbereich Medizintechnik und Technomathematik OPUS4-10998 unpublished Ringers, Christa, ; Bialonski, Stephan, bialonski@fh-aachen.de; Solovev, Anton, ; Hansen, Jan N., ; Ege, Mert, ; Friedrich, Benjamin M., ; Jurisch-Yaksi, Nathalie, Preprint: Local synchronization of cilia and tissue-scale cilia alignment are sufficient for global metachronal waves Motile cilia are hair-like cell extensions present in multiple organs of the body. How cilia coordinate their regular beat in multiciliated epithelia to move fluids remains insufficiently understood, particularly due to lack of rigorous quantification. We combine here experiments, novel analysis tools, and theory to address this knowledge gap. We investigate collective dynamics of cilia in the zebrafish nose, due to its conserved properties with other ciliated tissues and its superior accessibility for non-invasive imaging. We revealed that cilia are synchronized only locally and that the size of local synchronization domains increases with the viscosity of the surrounding medium. Despite the fact that synchronization is local only, we observed global patterns of traveling metachronal waves across the multiciliated epithelium. Intriguingly, these global wave direction patterns are conserved across individual fish, but different for left and right nose, unveiling a chiral asymmetry of metachronal coordination. To understand the implications of synchronization for fluid pumping, we used a computational model of a regular array of cilia. We found that local metachronal synchronization prevents steric collisions and improves fluid pumping in dense cilia carpets, but hardly affects the direction of fluid flow. In conclusion, we show that local synchronization together with tissue-scale cilia alignment are sufficient to generate metachronal wave patterns in multiciliated epithelia, which enhance their physiological function of fluid pumping. 2021 19 Seiten bioRxiv Veröffentlicht in eLife 12:e77701 (https://doi.org/10.7554/eLife.77701). 10.1101/2021.11.23.469646 weltweit https://www.biorxiv.org/content/10.1101/2021.11.23.469646v3 (Preprint) Fachbereich Medizintechnik und Technomathematik OPUS4-10996 Wissenschaftlicher Artikel Yang, Peng-Fei, ; Kriechbaumer, Andreas, ; Albracht, Kirsten, Albracht@fh-aachen.de; Sanno, Maximilian, ; Ganse, Bergita, ; Koy, Timmo, ; Shang, Peng, ; brüggemann, Gert-Peter, ; Müller, Lars Peter, ; Rittweger, Jörn, A novel optical approach for assessing in vivo bone segment deformation and its application in muscle-bone relationship studies in humans Singapore Elsevier 2014 0 Journal of Orthopaedic Translation 2 4 238 238 10.1016/j.jot.2014.07.078 https://www.sciencedirect.com/science/article/pii/S2214031X14001582?via%3Dihub Fachbereich Medizintechnik und Technomathematik OPUS4-10994 Wissenschaftlicher Artikel Werkhausen, Amelie, ; Albracht, Kirsten, Albracht@fh-aachen.de; Cronin, Neil J, ; Paulsen, Gøran, ; Bojsen-Møller, Jens, ; Seynnes, Olivier R, Effect of training-induced changes in achilles tendon stiffness on muscle-tendon behavior during landing During rapid deceleration of the body, tendons buffer part of the elongation of the muscle-tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle-tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarflexion force, peak Achilles tendon strain and stiffness were measured during isometric contractions, using a combination of dynamometry, ultrasound and kinematics data. Additionally, testing included a step-landing task, during which joint mechanics and lengths of gastrocnemius and soleus fascicles, Achilles tendon, and MTU were determined using synchronized ultrasound, kinematics and kinetics data collection. After training, plantarflexion strength and Achilles tendon stiffness increased (15 and 18%, respectively), and tendon strain during landing remained similar. Likewise, lengthening and negative work produced by the gastrocnemius MTU did not change detectably. However, in the training group, gastrocnemius fascicle length was offset (8%) to a longer length at touch down and, surprisingly, fascicle lengthening and velocity were reduced by 27 and 21%, respectively. These changes were not observed for soleus fascicles when accounting for variation in task execution between tests. These results indicate that a training-induced increase in tendon stiffness does not noticeably affect the buffering action of the tendon when the MTU is rapidly stretched. Reductions in gastrocnemius fascicle lengthening and lengthening velocity during landing occurred independently from tendon strain. Future studies are required to provide insight into the mechanisms underpinning these observations and their influence on energy dissipation. Lausanne Frontiers Research Foundation 2018 11 Seiten Frontiers in physiology 9 10.3389/fphys.2018.00794 https://pubmed.ncbi.nlm.nih.gov/29997526/ Fachbereich Medizintechnik und Technomathematik OPUS4-10990 Wissenschaftlicher Artikel Ketelhut, Maike, ; Göll, Fabian, ; Braunstein, Björn, ; Albracht, Kirsten, Albracht@fh-aachen.de; Abel, Dirk, Comparison of different training algorithms for the leg extension training with an industrial robot In the past, different training scenarios have been developed and implemented on robotic research platforms, but no systematic analysis and comparison have been done so far. This paper deals with the comparison of an isokinematic (motion with constant velocity) and an isotonic (motion against constant weight) training algorithm. Both algorithms are designed for a robotic research platform consisting of a 3D force plate and a high payload industrial robot, which allows leg extension training with arbitrary six-dimensional motion trajectories. In the isokinematic as well as the isotonic training algorithm, individual paths are defined i n C artesian s pace by sufficient s upport p oses. I n t he i sotonic t raining s cenario, the trajectory is adapted to the measured force as the robot should only move along the trajectory as long as the force applied by the user exceeds a minimum threshold. In the isotonic training scenario however, the robot's acceleration is a function of the force applied by the user. To validate these findings, a simulative experiment with a simple linear trajectory is performed. For this purpose, the same force path is applied in both training scenarios. The results illustrate that the algorithms differ in the force dependent trajectory adaption. Berlin De Gruyter 2018 3 Current Directions in Biomedical Engineering 4 1 17 20 10.1515/cdbme-2018-0005 https://doi.org/10.1515/cdbme-2018-0005 Fachbereich Medizintechnik und Technomathematik OPUS4-10989 Wissenschaftlicher Artikel Werkhausen, Amelie, ; Cronin, Neil J., ; Albracht, Kirsten, Albracht@fh-aachen.de; Paulsen, Gøran, ; Larsen, Askild V., ; Bojsen-Møller, Jens, ; Seynnes, Olivier R., Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running Background During the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus. Methods Eleven subjects were assigned to a training group performing isometric singleleg plantarflexion contractions three times per week for ten weeks, and another ten subjects formed a control group. Before and after the training period, Achilles tendon stiffness was estimated, and muscle-tendon mechanics were assessed during running at preferred speed using ultrasonography, kinematics and kinetics. Results Achilles tendon stiffness increased by 18% (P <0:01) in the training group, but the associated reduction in strain seen during isometric contractions was not statistically significant. Tendon elongation during the stance phase of running was similar after training, but tendon recoil was reduced by 30% (P <0:01), while estimated tendon force remained unchanged. Neither gastrocnemius medialis nor soleus fascicle shortening during stance was affected by training. Discussion These results show that a training-induced increase in Achilles tendon stiffness altered tendon behaviour during running. Despite training-induced changes in tendon mechanical properties and recoil behaviour, the data suggest that fascicle shortening patterns were preserved for the running speed that we examined. The asymmetrical changes in tendon strain patterns supports the notion that simple inseries models do not fully explain the mechanical output of the muscle-tendon unit during a complex task like running. London Peer 2019 18 Seiten PeerJ 10.7717/peerj.6764 https://doi.org/10.7717/peerj.6764 Fachbereich Medizintechnik und Technomathematik OPUS4-10987 misc Blottner, Dieter, ; Hastermann, Maria, ; Muckelt, Paul, ; Albracht, Kirsten, Albracht@fh-aachen.de; Schoenrock, Britt, ; Salanova, Michele, ; Warner, Martin, ; Gunga, Hans-Christian, ; Stokes, Maria, MYOTONES - Inflight muscle health status monitoring during long-duration space missions onboard the International Space Station: a single case study The MYOTONES experiment is the first to monitor changes in the basic biomechanical properties (tone, elasticity and stiffness) of the resting human myofascial system due to microgravity with a oninvasive, portable device on board the ISS. The MyotonPRO device applies several brief mechanical stimuli to the surface of the skin, and the natural oscillation signals of the tissue beneath are detected and computed by the MyotonPRO. Thus, an objective, quick and easy determination of the state of the underlying tissue is possible. Two preflight, four inflight and four post flight measurements were performed on a male astronaut using the same 10 measurement points (MP) for each session. MPs were located on the plantar fascia, Achilles tendon, M. soleus, M. gastrocnemius, M. multifidus, M. splenius capitis, M. deltoideus anterior, M. rectus femoris, infrapatellar tendon, M. tibialis anterior. Subcutaneous tissues thickness above the MPs was measured using ultrasound imaging. Magnetic resonance images (MRI) of lower limb muscles and functional tests were also performed pre- and postflight. Our first measurements on board the ISS confirmed increased tone and stiffness of the lumbar multifidus muscle, an important trunk stabilizer, dysfunction of which is known to be associated with back pain. Furthermore, reduced tone and stiffness of Achilles tendon and plantar fascia were observed inflight vs. preflight, confirming previous findings from terrestrial analog studies and parabolic flights. Unexpectedly, the deltoid showed negative inflight changes in tone and stiffness, and increased elasticity, suggesting a potential risk of muscle atrophy in longer spaceflight that should be addressed by adequate inflight countermeasure protocols. Most values from limb and back MPS showed deflected patterns (in either directions) from inflight shortly after the re-entry phase on the landing day and one week later. Most parameter values then normalized to baseline after 3 weeks likely due to 1G re-adaptation and possible outcome of the reconditioning protocol. No major changes in subcutaneous tissues thickness above the MPs were found inflight vs preflight, suggesting no bias (i.e., fluid shift, extreme tissue thickening or loss). Pre- and postflight MRI and functional tests showed negligible changes in calf muscle size, power and force, which is likely due to training effects from current inflight exercise protocols. The MYOTONES experiment is currently ongoing to collect data from further crew members. The potential impact of this research is to better understand the effects of microgravity and countermeasures over the time course of an ISS mission cycle. This will enable exercise countermeasures to be tailored Oxford Pergamon 2019 2 Seiten IAC Papers Archive International Astronautical Congress: space: the power of the past, the promise of the future - Washington DC, USA/Vereinigte Staaten von Amerika Dauer: 21.10.2019 → 25.10.2019 https://iafastro.directory/iac/paper/id/55065/summary/ Fachbereich Medizintechnik und Technomathematik OPUS4-10986 Konferenzveröffentlichung Ketelhut, Maike, ; Göll, Fabian, ; Braunstein, Bjoern, ; Albracht, Kirsten, Albracht@fh-aachen.de; Abel, Dirk, Iterative learning control of an industrial robot for neuromuscular training Effective training requires high muscle forces potentially leading to training-induced injuries. Thus, continuous monitoring and controlling of the loadings applied to the musculoskeletal system along the motion trajectory is required. In this paper, a norm-optimal iterative learning control algorithm for the robot-assisted training is developed. The algorithm aims at minimizing the external knee joint moment, which is commonly used to quantify the loading of the medial compartment. To estimate the external knee joint moment, a musculoskeletal lower extremity model is implemented in OpenSim and coupled with a model of an industrial robot and a force plate mounted at its end-effector. The algorithm is tested in simulation for patients with varus, normal and valgus alignment of the knee. The results show that the algorithm is able to minimize the external knee joint moment in all three cases and converges after less than seven iterations. New York IEEE 2019 7 Seiten 2019 IEEE Conference on Control Technology and Applications 978-1-7281-2767-5 (ePub) 2019 IEEE Conference on Control Technology and Applications (CCTA) Hong Kong, China, August 19-21, 2019 10.1109/CCTA.2019.8920659 campus https://doi.org/10.1109/CCTA.2019.8920659 Fachbereich Medizintechnik und Technomathematik OPUS4-10985 Wissenschaftlicher Artikel Ketelhut, Maike, ; Kolditz, Melanie, ; Göll, Fabian, ; Braunstein, Bjoern, ; Albracht, Kirsten, albracht@fh-aachen.de; Abel, Dirk, Admittance control of an industrial robot during resistance training Neuromuscular strength training of the leg extensor muscles plays an important role in the rehabilitation and prevention of age and wealth related diseases. In this paper, we focus on the design and implementation of a Cartesian admittance control scheme for isotonic training, i.e. leg extension and flexion against a predefined weight. For preliminary testing and validation of the designed algorithm an experimental research and development platform consisting of an industrial robot and a force plate mounted at its end-effector has been used. Linear, diagonal and arbitrary two-dimensional motion trajectories with different weights for the leg extension and flexion part are applied. The proposed algorithm is easily adaptable to trajectories consisting of arbitrary six-dimensional poses and allows the implementation of individualized trajectories. Amsterdam Elsevier 2019 5 IFAC-PapersOnLine 52 14th IFAC Symposium on Analysis, Design, and Evaluation of Human Machine Systems HMS 2019 Tallinn, Estonia, 16-91 September 2019 19 223 228 10.1016/j.ifacol.2019.12.102 https://doi.org/10.1016/j.ifacol.2019.12.102 Fachbereich Medizintechnik und Technomathematik OPUS4-10982 Wissenschaftlicher Artikel Ketelhut, Maike, ; Brügge, G. M., ; Göll, Fabian, ; Braunstein, Bjoern, ; Albracht, Kirsten, albracht@fh-aachen.de; Abel, Dirk, Adaptive iterative learning control of an industrial robot during neuromuscular training To prevent the reduction of muscle mass and loss of strength coming along with the human aging process, regular training with e.g. a leg press is suitable. However, the risk of training-induced injuries requires the continuous monitoring and controlling of the forces applied to the musculoskeletal system as well as the velocity along the motion trajectory and the range of motion. In this paper, an adaptive norm-optimal iterative learning control algorithm to minimize the knee joint loadings during the leg extension training with an industrial robot is proposed. The response of the algorithm is tested in simulation for patients with varus, normal and valgus alignment of the knee and compared to the results of a higher-order iterative learning control algorithm, a robust iterative learning control and a recently proposed conventional norm-optimal iterative learning control algorithm. Although significant improvements in performance are made compared to the conventional norm-optimal iterative learning control algorithm with a small learning factor, for the developed approach as well as the robust iterative learning control algorithm small steady state errors occur. Amsterdam Elsevier 2020 7 IFAC PapersOnLine 53 2 16468 16475 10.1016/j.ifacol.2020.12.741 weltweit https://doi.org/10.1016/j.ifacol.2020.12.741 Fachbereich Medizintechnik und Technomathematik