TY - JOUR A1 - Kindmann, Rolf A1 - Kraus, Matthias A1 - Laumann, Jörg A1 - Vette, Jan T1 - Verallgemeinerte Berechnungsmethode für in Beton eingespannte Stahlprofile – Einspanntiefen, Tragfähigkeitsnachweise und Bemessungshilfen JF - Stahlbau N2 - Stützen und Träger aus Stahlprofilen können in Fundamente oder Wände aus Stahlbeton einbetoniert werden. Diese Anschlüsse wirken in der Regel wie Einspannungen, die eine ausreichende Einspanntiefe erfordern. Im Folgenden wird eine verallgemeinerte Berechnungsmethode für in Stahlbetonkonstruktionen eingespannte Stahlprofile aus gewalzten I-Profilen, geschweißten I-Profilen, runden Hohlprofilen, eckigen Hohlprofilen und einzelligen Kastenquerschnitten vorgestellt. Für Beanspruchungen infolge einachsiger Biegung um die starke und schwache Profilachse werden der profilabhängige Ansatz der Betondruckspannungen im Einspannbereich und die Ermittlung der Einspanntiefe behandelt. Unter Berücksichtigung der Normalkraft werden an den maßgebenden Stellen Tragfähigkeitsnachweise für die Stahlprofile geführt. Als Ergänzung zu den Berechnungsformeln werden Bemessungshilfen zur Verfügung gestellt, die die Wahl der mitwirkenden Breiten und der Einspanntiefen erleichtert. KW - Stahlprofile KW - Anschlüsse an Stahlbeton KW - Einspanntiefen KW - Eingespannte Stützen und Träger KW - steel profiles Y1 - 2022 U6 - http://dx.doi.org/10.1002/stab.202200024 SN - 1437-1049 VL - 93 IS - Early View SP - 1 EP - 25 PB - Ernst & Sohn GmbH CY - Berlin ER - TY - JOUR A1 - Molinnus, Denise A1 - Iken, Heiko A1 - Johnen, Anna Lynn A1 - Richstein, Benjamin A1 - Hellmich, Lena A1 - Poghossian, Arshak A1 - Knoch, Joachim A1 - Schöning, Michael Josef T1 - Miniaturized pH-Sensitive Field-Effect Capacitors with Ultrathin Ta₂O₅ Films Prepared by Atomic Layer Deposition JF - physica status solidi (a) applications and materials science N2 - Miniaturized electrolyte–insulator–semiconductor capacitors (EISCAPs) with ultrathin gate insulators have been studied in terms of their pH-sensitive sensor characteristics: three different EISCAP systems consisting of Al–p-Si–Ta2O5(5 nm), Al–p-Si–Si3N4(1 or 2 nm)–Ta2O5 (5 nm), and Al–p-Si–SiO2(3.6 nm)–Ta2O5(5 nm) layer structures are characterized in buffer solution with different pH values by means of capacitance–voltage and constant capacitance method. The SiO2 and Si3N4 gate insulators are deposited by rapid thermal oxidation and rapid thermal nitridation, respectively, whereas the Ta2O5 film is prepared by atomic layer deposition. All EISCAP systems have a clear pH response, favoring the stacked gate insulators SiO2–Ta2O5 when considering the overall sensor characteristics, while the Si3N4(1 nm)–Ta2O5 stack delivers the largest accumulation capacitance (due to the lower equivalent oxide thickness) and a higher steepness in the slope of the capacitance–voltage curve among the studied stacked gate insulator systems. KW - atomic layer deposition KW - capacitive field-effect sensors KW - pH sensors KW - ultrathin gate insulators Y1 - 2022 U6 - http://dx.doi.org/10.1002/pssa.202100660 SN - 1862-6319 VL - 219 IS - 8 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Bhattarai, Aroj A1 - Horbach, Andreas A1 - Staat, Manfred A1 - Kowalczyk, Wojciech A1 - Tran, Thanh Ngoc T1 - Virgin passive colon biomechanics and a literature review of active contraction constitutive models JF - Biomechanics N2 - The objective of this paper is to present our findings on the biomechanical aspects of the virgin passive anisotropic hyperelasticity of the porcine colon based on equibiaxial tensile experiments. Firstly, the characterization of the intestine tissues is discussed for a nearly incompressible hyperelastic fiber-reinforced Holzapfel–Gasser–Ogden constitutive model in virgin passive loading conditions. The stability of the evaluated material parameters is checked for the polyconvexity of the adopted strain energy function using positive eigenvalue constraints of the Hessian matrix with MATLAB. The constitutive material description of the intestine with two collagen fibers in the submucosal and muscular layer each has been implemented in the FORTRAN platform of the commercial finite element software LS-DYNA, and two equibiaxial tensile simulations are presented to validate the results with the optical strain images obtained from the experiments. Furthermore, this paper also reviews the existing models of the active smooth muscle cells, but these models have not been computationally studied here. The review part shows that the constitutive models originally developed for the active contraction of skeletal muscle based on Hill’s three-element model, Murphy’s four-state cross-bridge chemical kinetic model and Huxley’s sliding-filament hypothesis, which are mainly used for arteries, are appropriate for numerical contraction numerical analysis of the large intestine. KW - virgin passive KW - strain energy function KW - smooth muscle contraction KW - viscoelasticity KW - damage Y1 - 2022 U6 - http://dx.doi.org/10.3390/biomechanics2020013 SN - 2673-7078 VL - 2 IS - 2 SP - 138 EP - 157 PB - MDPI CY - Basel ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. A1 - Erpicum, Sebastien A1 - Peltier, Yann A1 - Dewals, Benjamin T1 - Unsteady shallow meandering flows in rectangular reservoirs: a modal analysis of URANS modelling JF - Journal of Hydro-environment Research N2 - Shallow flows are common in natural and human-made environments. Even for simple rectangular shallow reservoirs, recent laboratory experiments show that the developing flow fields are particularly complex, involving large-scale turbulent structures. For specific combinations of reservoir size and hydraulic conditions, a meandering jet can be observed. While some aspects of this pseudo-2D flow pattern can be reproduced using a 2D numerical model, new 3D simulations, based on the unsteady Reynolds-Averaged Navier-Stokes equations, show consistent advantages as presented herein. A Proper Orthogonal Decomposition was used to characterize the four most energetic modes of the meandering jet at the free surface level, allowing comparison against experimental data and 2D (depth-averaged) numerical results. Three different isotropic eddy viscosity models (RNG k-ε, k-ε, k-ω) were tested. The 3D models accurately predicted the frequency of the modes, whereas the amplitudes of the modes and associated energy were damped for the friction-dominant cases and augmented for non-frictional ones. The performance of the three turbulence models remained essentially similar, with slightly better predictions by RNG k-ε model in the case with the highest Reynolds number. Finally, the Q-criterion was used to identify vortices and study their dynamics, assisting on the identification of the differences between: i) the three-dimensional phenomenon (here reproduced), ii) its two-dimensional footprint in the free surface (experimental observations) and iii) the depth-averaged case (represented by 2D models). KW - coherent structures KW - hydraulic modelling KW - model performance KW - Proper Orthogonal Decomposition KW - Q-criterion Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.jher.2022.03.002 SN - 1570-6443 IS - In Press PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pfaff, Raphael A1 - Enning, Manfred A1 - Sutter, Stefan T1 - A risk‑based approach to automatic brake tests for rail freight service: incident analysis and realisation concept JF - SN Applied Sciences N2 - This study reviews the practice of brake tests in freight railways, which is time consuming and not suitable to detect certain failure types. Public incident reports are analysed to derive a reasonable brake test hardware and communication architecture, which aims to provide automatic brake tests at lower cost than current solutions. The proposed solutions relies exclusively on brake pipe and brake cylinder pressure sensors, a brake release position switch as well as radio communication via standard protocols. The approach is embedded in the Wagon 4.0 concept, which is a holistic approach to a smart freight wagon. The reduction of manual processes yields a strong incentive due to high savings in manual labour and increased productivity. KW - Freight rail KW - Brake test KW - Incident analysis KW - Train composition KW - Brake set-up Y1 - 2022 U6 - http://dx.doi.org/10.1007/s42452-022-05007-x SN - 2523-3971 N1 - Corresponding author: Raphael Pfaff VL - 4 IS - 4 SP - 1 EP - 14 PB - Springer CY - Cham ER - TY - JOUR A1 - Kaulen, Lars A1 - Schwabedal, Justus T. C. A1 - Schneider, Jules A1 - Ritter, Philipp A1 - Bialonski, Stephan T1 - Advanced sleep spindle identification with neural networks JF - Scientific Reports N2 - Sleep spindles are neurophysiological phenomena that appear to be linked to memory formation and other functions of the central nervous system, and that can be observed in electroencephalographic recordings (EEG) during sleep. Manually identified spindle annotations in EEG recordings suffer from substantial intra- and inter-rater variability, even if raters have been highly trained, which reduces the reliability of spindle measures as a research and diagnostic tool. The Massive Online Data Annotation (MODA) project has recently addressed this problem by forming a consensus from multiple such rating experts, thus providing a corpus of spindle annotations of enhanced quality. Based on this dataset, we present a U-Net-type deep neural network model to automatically detect sleep spindles. Our model’s performance exceeds that of the state-of-the-art detector and of most experts in the MODA dataset. We observed improved detection accuracy in subjects of all ages, including older individuals whose spindles are particularly challenging to detect reliably. Our results underline the potential of automated methods to do repetitive cumbersome tasks with super-human performance. Y1 - 2022 U6 - http://dx.doi.org/10.1038/s41598-022-11210-y SN - 2045-2322 N1 - Corresponding author: Stephan Bialonski VL - 12 IS - Article number: 7686 SP - 1 EP - 10 PB - Springer Nature CY - London ER - TY - JOUR A1 - Ulmer, Jessica A1 - Braun, Sebastian A1 - Cheng, Chi-Tsun A1 - Dowey, Steve A1 - Wollert, Jörg T1 - Gamification of virtual reality assembly training: Effects of a combined point and level system on motivation and training results JF - International Journal of Human-Computer Studies N2 - Virtual Reality (VR) offers novel possibilities for remote training regardless of the availability of the actual equipment, the presence of specialists, and the training locations. Research shows that training environments that adapt to users' preferences and performance can promote more effective learning. However, the observed results can hardly be traced back to specific adaptive measures but the whole new training approach. This study analyzes the effects of a combined point and leveling VR-based gamification system on assembly training targeting specific training outcomes and users' motivations. The Gamified-VR-Group with 26 subjects received the gamified training, and the Non-Gamified-VR-Group with 27 subjects received the alternative without gamified elements. Both groups conducted their VR training at least three times before assembling the actual structure. The study found that a level system that gradually increases the difficulty and error probability in VR can significantly lower real-world error rates, self-corrections, and support usages. According to our study, a high error occurrence at the highest training level reduced the Gamified-VR-Group's feeling of competence compared to the Non-Gamified-VR-Group, but at the same time also led to lower error probabilities in real-life. It is concluded that a level system with a variable task difficulty should be combined with carefully balanced positive and negative feedback messages. This way, better learning results, and an improved self-evaluation can be achieved while not causing significant impacts on the participants' feeling of competence. KW - Gamification KW - Virtual reality KW - Assembly KW - User study KW - Level system Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.ijhcs.2022.102854 SN - 1071-5819 VL - 165 IS - Art. No. 102854 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Mueller, Tobias A1 - Segin, Alexander A1 - Weigand, Christoph A1 - Schmitt, Robert H. T1 - Feature selection for measurement models JF - International journal of quality & reliability management N2 - Purpose In the determination of the measurement uncertainty, the GUM procedure requires the building of a measurement model that establishes a functional relationship between the measurand and all influencing quantities. Since the effort of modelling as well as quantifying the measurement uncertainties depend on the number of influencing quantities considered, the aim of this study is to determine relevant influencing quantities and to remove irrelevant ones from the dataset. Design/methodology/approach In this work, it was investigated whether the effort of modelling for the determination of measurement uncertainty can be reduced by the use of feature selection (FS) methods. For this purpose, 9 different FS methods were tested on 16 artificial test datasets, whose properties (number of data points, number of features, complexity, features with low influence and redundant features) were varied via a design of experiments. Findings Based on a success metric, the stability, universality and complexity of the method, two FS methods could be identified that reliably identify relevant and irrelevant influencing quantities for a measurement model. Originality/value For the first time, FS methods were applied to datasets with properties of classical measurement processes. The simulation-based results serve as a basis for further research in the field of FS for measurement models. The identified algorithms will be applied to real measurement processes in the future. KW - Feature selection KW - Modelling KW - Measurement models KW - Measurement uncertainty Y1 - 2022 U6 - http://dx.doi.org/10.1108/IJQRM-07-2021-0245 SN - 0265-671X IS - Vol. ahead-of-print, No. ahead-of-print. PB - Emerald Group Publishing Limited CY - Bingley ER - TY - JOUR A1 - Röthenbacher, Annika A1 - Cesari, Matteo A1 - Doppler, Christopher E.J. A1 - Okkels, Niels A1 - Willemsen, Nele A1 - Sembowski, Nora A1 - Seger, Aline A1 - Lindner, Marie A1 - Brune, Corinna A1 - Stefani, Ambra A1 - Högl, Birgit A1 - Bialonski, Stephan A1 - Borghammer, Per A1 - Fink, Gereon R. A1 - Schober, Martin A1 - Sommerauer, Michael T1 - RBDtector: an open-source software to detect REM sleep without atonia according to visual scoring criteria JF - Scientific Reports N2 - REM sleep without atonia (RSWA) is a key feature for the diagnosis of rapid eye movement (REM) sleep behaviour disorder (RBD). We introduce RBDtector, a novel open-source software to score RSWA according to established SINBAR visual scoring criteria. We assessed muscle activity of the mentalis, flexor digitorum superficialis (FDS), and anterior tibialis (AT) muscles. RSWA was scored manually as tonic, phasic, and any activity by human scorers as well as using RBDtector in 20 subjects. Subsequently, 174 subjects (72 without RBD and 102 with RBD) were analysed with RBDtector to show the algorithm’s applicability. We additionally compared RBDtector estimates to a previously published dataset. RBDtector showed robust conformity with human scorings. The highest congruency was achieved for phasic and any activity of the FDS. Combining mentalis any and FDS any, RBDtector identified RBD subjects with 100% specificity and 96% sensitivity applying a cut-off of 20.6%. Comparable performance was obtained without manual artefact removal. RBD subjects also showed muscle bouts of higher amplitude and longer duration. RBDtector provides estimates of tonic, phasic, and any activity comparable to human scorings. RBDtector, which is freely available, can help identify RBD subjects and provides reliable RSWA metrics. Y1 - 2022 U6 - http://dx.doi.org/10.1038/s41598-022-25163-9 SN - 2045-2322 VL - 12 IS - Article number: 20886 SP - 1 EP - 14 PB - Springer Nature CY - London ER - TY - JOUR A1 - Tran, Ngoc Trinh A1 - Trinh, Tu Luc A1 - Dao, Ngoc Tien A1 - Giap, Van Tan A1 - Truong, Manh Khuyen A1 - Dinh, Thuy Ha A1 - Staat, Manfred T1 - FEM shakedown analysis of structures under random strength with chance constrained programming JF - Vietnam Journal of Mechanics N2 - Direct methods, comprising limit and shakedown analysis, are a branch of computational mechanics. They play a significant role in mechanical and civil engineering design. The concept of direct methods aims to determine the ultimate load carrying capacity of structures beyond the elastic range. In practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and constraints. If strength and loading are random quantities, the shakedown analysis can be formulated as stochastic programming problem. In this paper, a method called chance constrained programming is presented, which is an effective method of stochastic programming to solve shakedown analysis problems under random conditions of strength. In this study, the loading is deterministic, and the strength is a normally or lognormally distributed variable. KW - limit analysis KW - shakedown analysis KW - chance constrained programming KW - stochastic programming KW - reliability of structures Y1 - 2022 U6 - http://dx.doi.org/10.15625/0866-7136/17943 SN - 0866-7136 SN - 2815-5882 VL - 44 IS - 4 SP - 459 EP - 473 PB - Vietnam Academy of Science and Technology (VAST) ER -