TY - JOUR A1 - Mayer, Matthias A1 - Rabindranath, Raman A1 - Börner, Juliane A1 - Hörner, Eva A1 - Bentz, Alexander A1 - Salgado, Josefina A1 - Han, Hong A1 - Böse, Holger A1 - Probst, Jörn A1 - Shamonin (Chamonine), Mikhail A1 - Monkman, Gareth J. A1 - Schlunck, Günther T1 - Ultra-Soft PDMS-Based Magnetoactive Elastomers as Dynamic Cell Culture Substrata JF - PLoS ONE N2 - Mechanical cues such as extracellular matrix stiffness and movement have a major impact on cell differentiation and function. To replicate these biological features in vitro, soft substrata with tunable elasticity and the possibility for controlled surface translocation are desirable. Here we report on the use of ultra-soft (Young’s modulus <100 kPa) PDMS-based magnetoactive elastomers (MAE) as suitable cell culture substrata. Soft non-viscous PDMS (<18 kPa) is produced using a modified extended crosslinker. MAEs are generated by embedding magnetic microparticles into a soft PDMS matrix. Both substrata yield an elasticity-dependent (14 vs. 100 kPa) modulation of α-smooth muscle actin expression in primary human fibroblasts. To allow for static or dynamic control of MAE material properties, we devise low magnetic field (≈40 mT) stimulation systems compatible with cell-culture environments. Magnetic field-instigated stiffening (14 to 200 kPa) of soft MAE enhances the spreading of primary human fibroblasts and decreases PAX-7 transcription in human mesenchymal stem cells. Pulsatile MAE movements are generated using oscillating magnetic fields and are well tolerated by adherent human fibroblasts. This MAE system provides spatial and temporal control of substratum material characteristics and permits novel designs when used as dynamic cell culture substrata or cell culture-coated actuator in tissue engineering applications or biomedical devices. Y1 - 2013 U6 - https://doi.org/10.1371/journal.pone.0076196 VL - 8 IS - 10 PB - PLOS ER - TY - JOUR A1 - Kral, Christian A1 - Kapeller, Hansjörg A1 - Gragger, Johannes V. A1 - Haumer, Anton A1 - Kubicek, Bernhard T1 - Phenomenon Rotor Fault-Multiple Electrical Rotor Asymmetries in Induction Machines JF - IEEE Transactions on Power Electronics N2 - In the literature, the effects caused by a single or several adjacently broken rotor bars, or a broken end ring are thoroughly investigated. The phenomenon of various nonadjacently broken rotor bars has not been studied so far in detail. Since nonadjacently broken rotor bars may give rise to fault signatures, which are not directly related with the fault extent, it is important to understand the nature of multiple electrical rotor asymmetries in induction machines. The purpose of this paper is thus to investigate several combinations of electrical rotor asymmetries, to systematically elaborate the phenomena related to the broken bars and end rings. In this paper, a sophisticated simulation model and measurement results are used to analyze the phenomenon rotor fault. KW - asynchronous machines KW - Electrical rotor asymmetries KW - induction machine KW - rotor fault KW - Rotors KW - simulation model KW - skewing Y1 - 2010 U6 - https://doi.org/10.1109/TPEL.2009.2037502 SN - 0885-8993 SN - 1941-0107 VL - 25 IS - 5 SP - 1124 EP - 1134 PB - IEEE ER - TY - JOUR A1 - Kral, Christian A1 - Haumer, Anton A1 - Haigis, Matthias A1 - Lang, Hermann A1 - Kapeller, Hansjörg T1 - Comparison of a CFD Analysis and a Thermal Equivalent Circuit Model of a TEFC Induction Machine With Measurements JF - IEEE Transactions on Energy Conversion N2 - For a totally enclosed fan-cooled induction machine, two methods of numerical analysis are compared with measurements. The first numerical method is based on computational fluid dynamics (CFDs) and the second one uses a thermal equivalent circuit (TEC). For the analysis based on CFD, a 3-D induction machine including housing is modeled. The numeric solution of the flow equations is determined for stationary temperature distributions. For the TEC, a discretized one-and-a-half-dimensional model of the induction machine is considered. With the TEC model, stationary and transient operating conditions can be simulated. Measurement results are determined by iron-copper-nickel sensors embedded in the stator winding and the housing, as well as by an IR sensor for measuring the rotor temperature. With these measurement signals, stationary and transient operating conditions can be analyzed. For stationary operating conditions, additionally, the housing temperatures are determined by an IR camera. The investigated simulation and measurement methods reveal different local and global temperatures, and thus, only certain aspects and characteristics of the obtained temperatures can be compared. Nevertheless, certain conclusions can be drawn from comparing these aspects considering the actual restrictions of each of the applied methods. KW - asynchronous machines KW - computational fluid dynamics KW - electric sensing devices KW - Fluid flow KW - induction machines KW - numerical analysis KW - simulation KW - temperature Y1 - 2009 U6 - https://doi.org/10.1109/TEC.2009.2025428 SN - 0885-8969 VL - 24 IS - 4 SP - 809 EP - 818 PB - IEEE ER - TY - JOUR A1 - Kral, Christian A1 - Haumer, Anton A1 - Lee, Sang Bin T1 - A Practical Thermal Model for the Estimation of Permanent Magnet and Stator Winding Temperatures JF - IEEE Transactions on Power Electronics N2 - A thermal model for the determination of the temperatures of interior permanent magnets and stator windings is presented in this paper. The innovation of the model relies on one temperature sensor being located in the stator core of the machine. Such sensor is simple to implement in many applications such as traction or EV, where reliability is critical. The estimated stator winding and permanent magnet temperatures are determined by a simplified thermal lumped element network model with only two time constants. It is shown that the proposed thermal model is very robust due to the structure of the model and the measured stator core temperature. The distortion of the temperature estimates caused by the cooling circuit is inherently accounted for such that the model can be used for robust online prediction of temperatures. Experimental results based on a forced water-cooled interior permanent magnet synchronous machine setup are presented to validate the effectiveness of the presented model. KW - cooling KW - lumped element thermal equivalent circuit model KW - magnetic cores KW - permanent magnet machines KW - permanent magnet synchronous machine KW - stators KW - synchronous machines KW - temperature estimation KW - variable speed KW - dynamic load Y1 - 2014 U6 - https://doi.org/10.1109/TPEL.2013.2253128 SN - 1941-0107 SN - 0885-8993 VL - 29 IS - 1 SP - 455 EP - 464 PB - IEEE ER - TY - CHAP A1 - Petchartee, Somrak A1 - Monkman, Gareth J. T1 - Contact Identification using Tactile Arrays T2 - Proceedings of the 7th IEEE International Symposium on Signal Processing and Information Technology (ISSPIT 2007), 15.-18.12.2007, Giza, Egypt N2 - The proposed method allows a robot to quantify tactile recognition of grasped objects. The responses by the robot are matched by randomly introducing objects following the completion of tactile sensor based training phases on 4 specific objects. The reproduction of the robotic contact identification is accomplished by matching threshold values of the smallest eigenvalue of the Quadric surface - called the eigenvalue trajectory. Once the grasped objects are introduced to the 2-fingered robot hand, the eigenvalue trajectory of contact surfaces are calculated by the system. Calculations are based on the degree of similarity of the characteristics between the newly received and previously trained tactile data. Experimental results indicate that the proposed algorithm allows a successful quantification of robotic contact recognition and the accomplishment of high levels of accuracy in contact identification. These results confirm that the proposed method is useful for identifying contact surfaces based on tactile sensor data. KW - Touch recognition KW - contact classification KW - tactile sensor Y1 - 2007 U6 - https://doi.org/10.1109/ISSPIT.2007.4458144 SP - 1121 EP - 1126 PB - IEEE ER - TY - JOUR A1 - Monkman, Gareth J. T1 - Workpiece Retention during Machine Processing JF - Assembly Automation N2 - Discusses the failings of conventional fixturing systems such as jigs and clamps and describes how electrorheological fluids can be used for flexible fixturing and workpiece retention. KW - Grippers KW - Rheology Y1 - 2001 U6 - https://doi.org/10.1108/01445150110381754 SN - 1758-4078 SN - 0144-5154 VL - 21 IS - 1 SP - 61 EP - 67 PB - Emerald CY - Bringley ER - TY - JOUR A1 - Monkman, Gareth J. T1 - Precise Piezoelectric Prehension JF - Industrial Robot N2 - Piezoelectric actuators are well established for use in expensive optical equipment. Within the last decade, relatively inexpensive piezoelectric actuators have become established technology in pneumatic switching and the first piezoelectrically driven impactive robot grippers are just starting to emerge. Although this article concentrates largely on the use of piezoelectric actuators for use in robot gripping systems, the potential for applications outside this field is immense. KW - Piezoelectric actuators KW - Robots KW - Grippers KW - Nanotechnology Y1 - 2000 U6 - https://doi.org/10.1108/01439910010371605 SN - 0143-991x VL - 27 IS - 3 SP - 189 EP - 194 PB - MCB University Press ER - TY - JOUR A1 - Monkman, Gareth J. T1 - Advances in Shape Memory Polymer Actuation JF - Mechatronics N2 - Shape memory materials fulfill an important role in both actuation and mechanical coupling between actuators and associated dynamic systems. The simplest techniques are thermally based and in addition to the more common shape memory alloys there are also shape memory polymers. These have similar characteristics to those of their metallic cousins, but there the relationship stops. The basic physical principles are very different and this paper attempts to outline the current state-of-the-art to those already involved with the technology and perhaps open a fresh chapter in smart materials to those who are new to it. Y1 - 2000 U6 - https://doi.org/10.1016/S0957-4158(99)00068-9 SN - 1873-4006 SN - 0957-4158 VL - 10 IS - 4/5 SP - 489 EP - 498 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kreitmeier, Florian A1 - Chashin, Dmitri V. A1 - Fetisov, Yuri K. A1 - Fetisov, Leonid Y. A1 - Schulz, Irene A1 - Monkman, Gareth J. A1 - Shamonin (Chamonine), Mikhail T1 - Nonlinear Magnetoelectric Response of Planar Ferromagnetic-Piezoelectric Structures to Sub-Millisecond Magnetic Pulses JF - Sensors N2 - The magnetoelectric response of bi- and symmetric trilayer composite structures to pulsed magnetic fields is experimentally investigated in detail. The structures comprise layers of commercially available piezoelectric (lead zirconate titanate) and magnetostrictive (permendur or nickel) materials. The magnetic-field pulses have the form of a half-wave sine function with duration of 450 µs and amplitudes ranging from 500 Oe to 38 kOe. The time dependence of the resulting voltage is presented and explained by theoretical estimations. Appearance of voltage oscillations with frequencies much larger than the reciprocal pulse length is observed for sufficiently large amplitudes (~1-10 kOe) of the magnetic-field pulse. The origin of these oscillations is the excitation of bending and planar acoustic oscillations in the structures. Dependencies of the magnetoelectric voltage coefficient on the excitation frequency and the applied magnetic field are calculated by digital signal processing and compared with those obtained by the method of harmonic field modulation. The results are of interest for developing magnetoelectric sensors of pulsed magnetic fields as well as for rapid characterization of magnetoelectric composite structures. Y1 - 2012 U6 - https://doi.org/10.3390/s121114821 N1 - Corresponding author: Mikhail Shamonin VL - 12 IS - 11 SP - 14821 EP - 14837 PB - MDPI CY - Basel ER - TY - JOUR A1 - Joseph, Saskia A1 - Schumm, Michael A1 - Rummel, Otmar A1 - Soska, Alexander A1 - Renschke, Michael A1 - Mottok, Jürgen A1 - Niemetz, Michael A1 - Schroll-Decker, Irmgard T1 - Teaching finite state machines with case method and role play JF - 2014 IEEE Global Engineering Education Conference (EDUCON 2014) : Istanbul, Turkey, 3 - 5 April 2014 N2 - The professional requirements in Software Engineering have become highly volatile due to the complexities of project development and rapid and innovative changes occurring in the field. Therefore, the development of inter-personal and social competences has gained central importance in the training of software developers. This paper will present a concept allowing to acquire competences by using Case Method and Role Play as instruments in several lectures of Software Engineering. By approaching the issue of competence acquisition on a technical as well as on an educational and social level, life-long learning is facilitated and supported. KW - Case Method KW - competences KW - learning arrangement KW - life-long learning KW - Role Play Y1 - 2013 U6 - https://doi.org/10.1109/EduCon.2013.6530275 SP - 1302 EP - 1305 PB - IEEE ER - TY - JOUR A1 - Reindl, Klaus A1 - Zheng, Yuanhang A1 - Schwarz, Andreas A1 - Meier, Stefan A1 - Maas, Roland A1 - Sehr, Armin A1 - Kellermann, Walter T1 - A stereophonic acoustic signal extraction scheme for noisy and reverberant environments JF - Computer Speech and Language N2 - In this contribution, a novel two-channel acoustic front-end for robust automatic speech recognition in adverse acoustic environments with nonstationary interference and reverberation is proposed. From a MISO system perspective, a statistically optimum source signal extraction scheme based on the multichannel Wiener filter (MWF) is discussed for application in noisy and underdetermined scenarios. For free-field and diffuse noise conditions, this optimum scheme reduces to a Delay & Sum beamformer followed by a single-channel Wiener postfilter. Scenarios with multiple simultaneously interfering sources and background noise are usually modeled by a diffuse noise field. However, in reality, the free-field assumption is very weak because of the reverberant nature of acoustic environments. Therefore, we propose to estimate this simplified MWF solution in each frequency bin separately to cope with reverberation. We show that this approach can very efficiently be realized by the combination of a blocking matrix based on semi-blind source separation (‘directional BSS’), which provides a continuously updated reference of all undesired noise and interference components separated from the desired source and its reflections, and a single-channel Wiener postfilter. Moreover, it is shown, how the obtained reference signal of all undesired components can efficiently be used to realize the Wiener postfilter, and at the same time, generalizes well-known postfilter realizations. The proposed front-end and its integration into an automatic speech recognition (ASR) system are analyzed and evaluated in noisy living-room-like environments according to the PASCAL CHiME challenge. A comparison to a simplified front-end based on a free-field assumption shows that the introduced system substantially improves the speech quality and the recognition performance under the considered adverse conditions. KW - Blind source extraction KW - Speech enhancement KW - Robust automatic speech recognition KW - PASCAL CHiME challenge Y1 - 2013 U6 - https://doi.org/10.1016/j.csl.2012.07.011 VL - 27 IS - 3 SP - 726 EP - 745 PB - Elsevier ER - TY - JOUR A1 - Schreier, Franz A1 - Kohlert, Dieter T1 - Optimized implementations of rational approximations-a case study on the Voigt and complex error function JF - Computer Physics Communications : an international journal for computational physics and physical chemistry N2 - Rational functions are frequently used as efficient yet accurate numerical approximations for real and complex valued special functions. For the complex error function , whose real part is the Voigt function , the rational approximation developed by Hui, Armstrong, and Wray [Rapid computation of the Voigt and complex error functions, J. Quant. Spectrosc. Radiat. Transfer 19 (1978) 509–516] is investigated. Various optimizations for the algorithm are discussed. In many applications, where these functions have to be calculated for a large x grid with constant y, an implementation using real arithmetic and factorization of invariant terms is especially efficient. Y1 - 2008 U6 - https://doi.org/10.1016/j.cpc.2008.04.012 SN - 0010-4655 VL - 179 IS - 7 SP - 457 EP - 465 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Petchartee, Somrak A1 - Monkman, Gareth J. T1 - Contact Classification using Tactile Arrays T2 - 2007 3rd International Conference on Intelligent Sensors, Sensor Networks and Information (ISSNIP), 3, 03.-06.12.2007, Melbourne, VIC, Australia N2 - This paper proposed a contact recognition algorithm capable of determining contact surfaces types by tactile sensor fusion. This algorithm can recognize grasped objects using a 2- fingered robot hand, on which tactile sensors are mounted. Experiments have demonstrated reliable surface classification and accurate transformation independent of object shape and orientation. The contribution of this paper regards the relations between a surface and the points cloud defining it. Particularly, we investigate on the possibility that there is some intrinsic feature of a points cloud under quadric surface, allowing us to discriminate or classify a dataset defining a surface from the acquisition noise. KW - manipulators KW - objec recognition KW - sensor arrays KW - signal classification KW - tactile sensors Y1 - 2007 U6 - https://doi.org/10.1109/ISSNIP.2007.4496848 SP - 227 EP - 232 ER - TY - CHAP A1 - Kreitmeier, Florian A1 - Schulz, Irene A1 - Monkman, Gareth J. A1 - Shamonin (Chamonine), Mikhail A1 - Fetisov, Yuri K. A1 - Chashin, Dmitri V. A1 - Fetisov, Leonid Y. T1 - Observation of Nonlinear Magnetoelectric Response to Magnetic Pulses in Layered Magnetostrictive-Piezoelectric Structures N2 - A detailed experimental study of the magnetoelectric response of planar bi- and symmetric trilayer composite structures to magnetic field pulses is reported. The structures consist of layers of commercially available piezoelectric (lead zirconate titanate) and magnetostrictive (permendur or nickel) materials. The magnetic-field pulses have the form of a half-wave sine function with duration of 450 μs and amplitude from 500 Oe up to 38 kOe. The measurement method is explained and the measured time dependence of the resulting voltage is presented. The most interesting case, when pulse amplitudes are sufficiently large (~ 1-10 kOe) and various types of acoustic oscillation with frequencies much larger than the reciprocal pulse length are excited in the structures, is considered. The dependencies of the magnetoelectric voltage coefficient on the excitation frequency and the applied magnetic field are calculated. By digital signal processing the results are compared with those obtained by the method of harmonic field modulation (HFM). The findings are of interest for developing magnetoelectric sensors for pulsed magnetic fields as well as for rapid characterization of magnetoelectric composite structures. T2 - Proceedings of 2012 21st IEEE ISAF held jointly with 11th IEEE ECAPD and IEEE PFM (ISAF/ECAPD/PFM), 9th-13th of July 2012, Aveiro, Portugal KW - composite materials KW - magnetoelectric effect KW - magnetoelectric sensors KW - magnetostriction KW - piezoelectricity KW - magnetic field pulse Y1 - 2012 U6 - https://doi.org/10.1109/ISAF.2012.6297739 PB - IEEE ER - TY - CHAP A1 - Maas, Roland A1 - Thippur, Akshaya A1 - Sehr, Armin A1 - Kellermann, Walter T1 - An uncertainty decoding approach to noise- and reverberation-robust speech recognition T2 - IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 26-31 May 2013, Vancouver, BC, Canada : Proceedings N2 - The generic REMOS (REverberation MOdeling for robust Speech recognition) concept is extended in this contribution to cope with additional noise components. REMOS originally embeds an explicit reverberation model into a hiddenMarkov model (HMM) leading to a relaxed conditional independence assumption for the observed feature vectors. During recognition, a nonlinear optimization problem is to be solved in order to adapt the HMMs' output probability density functions to the current reverberation conditions. The extension for additional noise components necessitates a modified numerical solver for the nonlinear optimization problem. We propose an approximation scheme based on continuous piecewise linear regression. Connected-digit recognition experiments demonstrate the potential of REMOS in reverberant and noisy environments. They furthermore reveal that the benefit of an explicit reverberation model, overcoming the conditional independence assumption, increases with increasing signal-to-noise-ratios. KW - Hidden Markov models KW - Reverberation KW - Noise KW - Speech KW - Adaptation models KW - Vectors KW - Optimization Y1 - 2013 U6 - https://doi.org/10.1109/ICASSP.2013.6639098 SP - 7388 EP - 7392 PB - IEEE ER - TY - JOUR A1 - Sehr, Armin A1 - Barfuss, Hendrik A1 - Hofmann, Christian A1 - Maas, Roland A1 - Kellermann, Walter T1 - Efficient training of acoustic models for reverberation-robust medium-vocabulary automatic speech recognition JF - 2014 4th Joint Workshop on Hands-Free Speech Communication and Microphone Arrays, HSCMA, 12-14 May 2014, Villers-les-Nancy, France N2 - A recently proposed concept for training reverberation-robust acoustic models for automatic speech recognition using pairs of clean and reverberant data is extended from word models to tied-state triphone models in this paper. The key idea of the concept, termed ICEWIND, is to use the clean data for the temporal alignment and the reverberant data for the estimation of the emission densities. Experiments with the 5000-word Wall Street Journal corpus confirm the benefits of ICEWIND with tied-state triphones: While the training time is reduced by more than 90%, the word accuracy is improved at the same time, both for room-specific and multi-style hidden Markov models. Since the acoustic models trained with ICEWIND need less Gaussian components for the emission densities to achieve comparable recognition rates as Baum-Welch acoustic models, ICEWIND also allows for a reduced decoding complexity. KW - Hidden Markov models KW - Training KW - Speech recognition KW - Speech KW - Vectors KW - Accuracy KW - Training data Y1 - 2014 U6 - https://doi.org/10.1109/HSCMA.2014.6843275 SP - 177 EP - 181 PB - IEEE ER - TY - JOUR A1 - Monkman, Gareth J. A1 - Egersdörfer, Stefan A1 - Meier, Alexander A1 - Böse, Holger A1 - Baumann, Michael A1 - Ermert, Helmut A1 - Kahled, W. A1 - Freimuth, Herbert T1 - Technologies for Haptic Displays in Teleoperation JF - Industrial Robot N2 - Since the 1960s many alphanumeric to tactile data conversion methods have been investigated, mainly with the ultimate aim of assisting the blind. More recently, interest has been directed toward the display of pictures on haptically explorable surfaces – tactile imaging – for a range of medical, remote sensing and entertainment purposes. This paper examines the technologies which have been utilised for haptically explorable tactile displays over the past three decades, focussing on those which appear commercially viable in the immediate future. Y1 - 2003 U6 - https://doi.org/10.1108/01439910310506792 SN - 0143-991x VL - 30 IS - 6 SP - 525 EP - 530 PB - Emerald ER - TY - JOUR A1 - Stoll, Andrea A1 - Mayer, Matthias A1 - Monkman, Gareth J. A1 - Shamonin (Chamonine), Mikhail T1 - Evaluation of highly compliant magneto-active elastomers with colossal magnetorheological response JF - Journal of applied polymer science N2 - Highly compliant elastomers with a shear storage modulus as low as 25 Pa are prepared using commercially available silicone, plasticizer, and tactile mutator silicone additive. They are used as matrix material for magneto-active elastomers (MAEs) with carbonyl iron contents between 0 and 85 wt %. In the absence of an external magnetic field, the storage modulus of MAEs based on two selected mixtures ranges between ~100 Pa and ~2000 Pa. Addition of a mutator to the matrix mixture results in a long post-cure period depending on the curing temperature and the initial mixture. In the presence of a magnetic field, the presented MAEs exhibit a strong magneto-induced change in storage modulus resulting in a colossal magnetorheological effect of >106 % which is ~30 times higher than previously reported values. The results are of interest in applications using such elastomers as cell substrates with magnetically tunable rigidity. Y1 - 2014 U6 - https://doi.org/10.1002/app.39793 SN - 1097-4628 SN - 0021-8995 PB - Wiley CY - New York, NY ER - TY - JOUR A1 - Forster, Eva A1 - Mayer, Matthias A1 - Rabindranath, Raman A1 - Böse, Holger A1 - Schlunck, Günther A1 - Monkman, Gareth J. A1 - Shamonin (Chamonine), Mikhail T1 - Patterning of ultrasoft, agglutinative magnetorheological elastomers JF - Journal of applied polymer science N2 - A low-cost wax-cast molding technique for structuring ultrasoft (Young’s modulus ≤ 40 kPa), agglutinative magnetorheological elastomer (MRE) material is presented. MRE structures ranging from a few millimeters down to the micrometer range with highly reproducible results are possible. Semitransparent MREs are also fabricated and their surfaces modified accordingly. This method opens new possibilities for MREs in biomedical engineering and microfluidic applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 Y1 - 2013 U6 - https://doi.org/10.1002/app.38500 VL - 128 IS - 4 SP - 2508 EP - 2515 PB - Wiley CY - New York, NY ER - TY - CHAP A1 - Maier, Robert A1 - Grabinger, Lisa A1 - Urlhart, David A1 - Mottok, Jürgen ED - Seguin, Christel ED - Zeller, Marc ED - Prosvirnova, Tatiana T1 - Towards Causal Model-Based Engineering in Automotive System Safety T2 - Model-Based Safety and Assessment, 8th International Symposium, IMBSA 2022: Munich, Germany, September 5–7, 2022, Proceedings N2 - Engineering is based on the understanding of causes and effects. Thus, causality should also guide the safety assessment of complex systems such as autonomous driving cars. To ensure the safety of the intended functionality of these systems, normative regulations like ISO 21448 recommend scenario-based testing. An important task here is to identify critical scenarios, so-called edge and corner cases. Data-driven approaches to this task (e.g. based on machine learning) cannot adequately address a constantly changing operational design domain. Model-based approaches offer a remedy – they allow including different sources of knowledge (e.g. data, human experts) into safety considerations. With this paper, we outline a novel approach for ensuring automotive system safety. We propose to use structural causal models as a probabilistic modelling language to combine knowledge about an open-context environment from different sources. Based on these models, we investigate parameter configurations that are candidates for critical scenarios. In this paper, we first discuss some aspects of scenario-based testing. We then provide an informal introduction to causal models and relate their development lifecycle to the established V-model. Finally, we outline a generic workflow for using causal models to identify critical scenarios and highlight some challenges that arise in the process. Y1 - 2022 U6 - https://doi.org/10.1007/978-3-031-15842-1_9 SP - 116 EP - 129 PB - Springer Nature CY - Cham ER - TY - CHAP A1 - Maier, Robert A1 - Mottok, Jürgen ED - Trapp, Mario ED - Saglietti, Francesca ED - Spisländer, Marc ED - Bitsch, Friedemann T1 - BayesianSafety - an Open-Source Package for Causality-Guided, Multi-Model Safety Analysis T2 - Computer Safety, Reliability, and Security, 41st International Conference (SAFECOMP 2022): Munich, Germany, September 6–9, 2022, Proceedings T2 - Lecture notes in computer science ; 13414 N2 - Development and verification of modern, dependable automotive systems require appropriate modelling approaches. Classic automotive safety is described by the normative regulations ISO 26262, its relative ISO/PAS 21448, and their respective methodologies. In recent publications, an emerging demand to combine environmental influences, machine learning, or reasoning under uncertainty with standard-compliant analysis techniques can be noticed. Therefore, adapting established methods like FTA and proper tool support is necessary. We argue that Bayesian Networks (BNs) can be used as a central component to address and merge these demands. In this paper, we present our Open-Source Python package BayesianSafety. First, we review how BNs relate to data-driven methods, model-to-model transformations, and causal reasoning. Together with FTA and ETA, these models form the core functionality of our software. After describing currently implemented features and possibilities of combining individual modelling approaches, we provide an informal view of the tool’s architecture and of the resulting software ecosystem. By comparing selected publicly available safety and reliability analysis libraries, we outline that many relevant methodologies yield specialized implementations. Finally, we show that there is a demand for a flexible, unifying analysis tool that allows researching system safety by using multi-model and multi-domain approaches. KW - Package BayesianSafety KW - Causality KW - Bayesian Networks KW - Event Tree Analysis KW - Fault Tree Analysis Y1 - 2022 U6 - https://doi.org/10.1007/978-3-031-14835-4_2 SP - 17 EP - 30 PB - Springer Nature CY - Cham ER - TY - CHAP A1 - Maier, Robert A1 - Mottok, Jürgen T1 - Causality and Functional Safety - How Causal Models Relate to the Automotive Standards ISO 26262, ISO/PAS 21448, and UL 4600 T2 - 27th International Conference on Applied Electronics (AE): 06-07 September 2022, Pilsen, CZ N2 - With autonomous driving, the system complexity of vehicles will increase drastically. This requires new approaches to ensure system safety. Looking at standards like ISO 26262 or ISO/PAS 21448 and their suggested methodologies, an increasing trend in the recent literature can be noticed to incorporate uncertainty. Often this is done by using Bayesian Networks as a framework to enable probabilistic reasoning. These models can also be used to represent causal relationships. Many publications claim to model cause-effect relations, yet rarely give a formal introduction of the implications and resulting possibilities such an approach may have. This paper aims to link the domains of causal reasoning and automotive system safety by investigating relations between causal models and approaches like FMEA, FTA, or GSN. First, the famous “Ladder of Causation” and its implications on causality are reviewed. Next, we give an informal overview of common hazard and reliability analysis techniques and associate them with probabilistic models. Finally, we analyse a mixed-model methodology called Hybrid Causal Logic, extend its idea, and build the concept of a causal shell model of automotive system safety. KW - Causality KW - Reliability KW - Functional Safety Y1 - 2022 U6 - https://doi.org/10.1109/AE54730.2022.9920053 PB - IEEE ER - TY - CHAP A1 - Frauenschläger, Tobias A1 - Mottok, Jürgen T1 - Security-Gateway for SCADA-Systems in Critical Infrastructures T2 - 27th International Conference on Applied Electronics (AE): 06-07 September 2022, Pilsen, CZ N2 - Supervisory Control and Data Acquisition (SCADA) systems are used to control and monitor components within the energy grid, playing a significant role in the stability of the system. As a part of critical infrastructures, components in these systems have to fulfill a variety of different requirements regarding their dependability and must also undergo strict audit procedures in order to comply with all relevant standards. This results in a slow adoption of new functionalities. Due to the emerged threat of cyberattacks against critical infrastructures, extensive security measures are needed within these systems to protect them from adversaries and ensure a stable operation. In this work, a solution is proposed to integrate extensive security measures into current systems. By deploying additional security-gateways into the communication path between two nodes, security features can be integrated transparently for the existing components. The developed security-gateway is compliant to all regulatory requirements and features an internal architecture based on the separation-of-concerns principle to increase its security and longevity. The viability of the proposed solution has been verified in different scenarios, consisting of realistic field tests, security penetration tests and various performance evaluations. KW - Critical Infrastructure KW - Certification KW - Supervisory Control and Data Acquisition KW - Security KW - Dependability Y1 - 2022 U6 - https://doi.org/10.1109/AE54730.2022.9920070 PB - IEEE ER - TY - CHAP A1 - Jahn, Sabrina A1 - Kaul, Nicolas A1 - Mottok, Jürgen T1 - Using or Misusing? Introducing Misuse Cases in a Software Engineering Course for Undergraduate Engineering Students T2 - ITiCSE '22 : Proceedings of the 27th ACM Conference on on Innovation and Technology in Computer Science Education, Vol 1: July 8 - 13, 2022, Dublin Ireland N2 - Today's cyberphysical systems are increasingly prone to misuse. To secure existing and future software systems, introducing concepts of IT-Security and Secure Software Engineering (SecSE) in Software Engineering (SE) courses is essential for academic education of future software engineers. This is not only important for computer science students, but also for engineering students studying topics of computing and SE. However, only little research exists on integrating these topics into traditional SE courses, especially for engineering students in non-computer science majors. To narrow this gap, this paper contributes with the design and evaluation of an exercise on modeling misuse cases alongside use cases, based on the inductive teaching method problem-based learning (PBL). The exercise is part of an educational design research investigating which learning content and teaching methods are suitable for integrating IT-Security and SecSE topics into traditional SE education of engineering students to convey factual knowledge as well as raise awareness and interest for both topics during software development. We present the integration of the exercise design into a traditional SE course for engineering students and its evaluation to examine its suitability. We evaluated the exercise design regarding the suitability of the design components, the learning content of misuse cases and the intended learning goals as well as its impact on students' motivation, and their interest in IT-security. The paper then presents indications on the feasibility and success of the exercise design for teaching misuse cases to engineering students and sparking their interest in IT-Security. KW - educational design research KW - mis-use case KW - problem-based learning KW - inductive teaching KW - engineering students KW - higher education KW - secure software engineering KW - IT-Security Y1 - 2022 U6 - https://doi.org/10.1145/3502718.3524823 SP - 491 EP - 497 PB - Association for Computing Machinery CY - New York, NY ER - TY - CHAP A1 - Grabinger, Lisa A1 - Hauser, Florian A1 - Mottok, Jürgen T1 - Accessing the Presentation of Causal Graphs and an Application of Gestalt Principles with Eye Tracking T2 - 2022 IEEE International Conference on Software Analysis, Evolution and Reengineering (SANER 2022), 1st Workshop on Advances in Human-Centric Experiments in Software Engineering (HUMAN 2022): 15-18 March 2022, Honolulu, HI, USA N2 - The discipline of causal inference uses so-called causal graphs to model cause and effect relations of random variables. As those graphs only encode a relation structure there is no hard rule concerning their alignment. The present paper presents a study with the aim of working out the optimal alignment of causal graphs with respect to comprehensibility and interestingness. In addition, the study examines whether the central gestalt principles of psychology apply for causal graphs. Data from 29 participants is acquired by triangulating eye tracking with a questionnaire. The results of the study suggest that causal graphs should be aligned downwards. Moreover, the gestalt principles proximity, similarity and closure are shown to hold true for causal graphs. KW - causal graphs KW - gestalt principles KW - eye tracking Y1 - 2022 U6 - https://doi.org/10.1109/SANER53432.2022.00153 SP - 1278 EP - 1285 PB - IEEE ER - TY - CHAP A1 - Schiedermeier, Maximilian A1 - Rettner, Cornelius A1 - Steiner, Marcel A1 - März, Martin T1 - Dual-inverter control synchronization strategy to minimize the DC-link capacitor current T2 - 2020 IEEE Vehicle Power and Propulsion Conference (VPPC), 18 November 2020 - 16 December 2020, Gijon, Spain N2 - This paper proposes the possible switching synchronization strategies of an automotive dual-inverter against the background of minimizing the RMS DC-link capacitor current. The publication mainly focuses on the straight-ahead motion of a rear axle with one electric drive per wheel. In addition to it, a dual-inverter consisting of two subinverters with a common DC-link capacitor is taken into consideration. These sub-inverters each have three phases and are based on a 2-level voltage-source-topology. To control the electrical machines, the continuous Space-Vector-Modulation strategy is used. For this application, different control signal synchronization strategies of the two sub-inverters of the dualinverter are presented. Apart from the existing strategies, this paper proposes a new method, which inherits a compromise between low complexity and high effectiveness. In contrast to previous publications, the resulting capacitor currents are quantified and subsequentlyevaluated. This novel quantification, which is dependent on the dual-inverter’s operating point, provides a base for targeted dimensioning of the capacitor. Moreover, this forms the foundation for further investigations of vehicle’s cornering, as well as for the possible synchronization of stand-alone inverters. In the context of this publication, the presented results are verified by experimentally determined data of a motor-inverter system. KW - Axles KW - Capacitors KW - Complexity theory KW - DC-link capacitor KW - Dual-inverter KW - interleaved inverters KW - Inverters KW - space vector modulation (SVM) KW - Switches KW - Synchronization KW - Voltage source inverter (VSI) KW - Wheels Y1 - 2020 U6 - https://doi.org/10.1109/VPPC49601.2020.9330921 SP - 1 EP - 6 PB - IEEE ER - TY - CHAP A1 - Reindl, Andrea A1 - Langer, Tobias A1 - Meier, Hans A1 - Niemetz, Michael T1 - Comparative Reliability Analysis for Single and Dual CAN (FD) Systems T2 - 27th 2022 International Conference on Applied Electronics (AE): 6-7 September 2022, Pilsen, Czech Republic N2 - Modern cyber-physical systems, such as autonomous vehicles, advanced driver assistance systems, automation systems and battery management systems, result in extended communication requirements regarding the reliability and the availability. The Controller Area Network (CAN) is a broadcast-based protocol which is still used as a standard for serial communication between individual microcontrollers due to its reliability and low power consumption. In addition, it provides mechanisms for detecting transmission errors and retransmitting messages in the event of an error. The enhancement CAN Flexible Data-Rate (CAN FD) offers increased data rates and transmission rates in order to meet the data throughput requirements. In this paper, the mechanisms for reliable data transmission in a CAN FD network are analyzed. To improve reliability, a second identical CAN-FD network is added to the system, using the additional CAN interface already available on common microcontrollers. The redundant communication network is examined in terms of failure rates and the mean time to failure. The reliability over the operation time is calculated for the single and the redundant version of the CAN FD network using the failure rate limits of the ASIL levels. Y1 - 2022 SN - 9781665494816 U6 - https://doi.org/10.1109/AE54730.2022.9920078 SP - 1 EP - 6 PB - IEEE ER - TY - JOUR A1 - Hofrichter, Andreas A1 - Rank, Daniel A1 - Heberl, Michael A1 - Sterner, Michael T1 - Determination of the optimal power ratio between electrolysis and renewable energy to investigate the effects on the hydrogen production costs JF - International Journal of Hydrogen Energy N2 - Green hydrogen via renewable powered electrolysis has a high relevance in decarbonization and supply security. Achieving economically competitive hydrogen production costs is a major challenge in times of an energy price crisis. Our objective is to show the economically optimal installed capacity of electrolysers in relation to wind and solar power so swift and credible statements can be made regarding the system design. The ratio between renewable generation and electrolysis power as well as scaling effects, operating behaviour and development of costs are considered. Hydrogen production costs are calculated for four exemplary real PV and wind sites and different ratios of electrolysis to renewable power for the year 2020. The ideal ratio for PV systems is between 14% and 73% and for wind between 3.3% and 143% for low and high full load hours. The lowest hydrogen production costs are identified at 2.53 €/kg for 50 MW wind power and 72 MW electrolysis power. The results provide plant constructors the possibility to create a cost-optimized design via an optimum ratio of electrolysis to renewable capacity. Therefore, the procedures for planning and dimensioning of selected systems can be drastically simplified. Y1 - 2023 U6 - https://doi.org/10.1016/j.ijhydene.2022.09.263 SN - 0360-3199 N1 - Corresponding author: Michael Heberl N1 - Corrigendum to “Determination of the optimal power ratio between electrolysis and renewable energy to investigate the effects on the hydrogen production costs” [Int J Hydrogen Energy 48 (5) (2023) 1651–1663] - https://doi.org/10.1016/j.ijhydene.2023.03.128 VL - 48 IS - 5 SP - 1651 EP - 1663 PB - Elsevier ER - TY - CHAP A1 - Körner, Patrick A1 - Reindl, Andrea A1 - Meier, Hans A1 - Niemetz, Michael T1 - A Theoretical Comparison of Different Virtual Synchronous Generator Implementations on Inverters T2 - 2022 24th European Conference on Power Electronics and Applications (EPE'22 ECCE Europe): 05-09 September 2022, Hannover, Germany N2 - The goal to overcome the global climate crisis leads to a rising demand for the usage of Renewable Energy Sources (RES). Decentralized control strategies are needed to allow the integration of RES into the grid. The Virtual Synchronous Generator (VSG) is proposed as a method to add virtual inertia to the grid by emulating the rotating mass of a Synchronous Generator (SG) on the control algorithm of an inverter. This paper presents the VSG control structure as well as the mathematical description in a unified form. Due to the fact that classical droop control can be seen as a special form of the VSG, their correlation is highlighted by evaluating the steady state output characteristics of the inverter. Furthermore, a theoretical comparison between different VSG topologies, including the VISMA-Method 2 and the synchronverter, is given. In order to achieve better voltage stability, principles to add virtual impedance to the inverter's output are described. Y1 - 2022 UR - https://ieeexplore.ieee.org/document/9907497 PB - IEEE ER - TY - CHAP A1 - Lalo, Erjola A1 - Sailer, Andreas A1 - Mottok, Jürgen A1 - Siemers, Christian T1 - Overhead-Aware Schedule Synthesis for Logical Execution Time (LET) in Automotive Systems T2 - 2022 IEEE 35th International System-on-Chip Conference (SOCC): 05-08 September 2022, Belfast, United Kingdom N2 - The Logical Execution Time (LET) has recently been integrated in multi-core automotive systems to ensure timing and dataflow determinism. Although buffering mechanisms are introduced to incorporate LET semantics, they do not guarantee that tasks are executed within their LET frames. In fact, LET and buffering semantics are violated if scheduling is not designed to execute all tasks within their LET frames and in a specific order. In this paper, we describe a scheduling synthesis technique for Fixed-Priority Scheduling (FPS) to achieve resource-efficient execution of LET systems. The proposed approach considers LET semantics, scheduling overheads, and delays caused by operating system operations and provides the possibility to optimize the schedule with respect to aspects like scheduling overheads. Our performance and feasibility evaluation shows that the proposed algorithm provides results in a reasonable amount of time for models of complex industrial applications. Thus, the integration of the proposed algorithm into an automated process is of high benefit to accelerate the development of vehicle applications. Y1 - 2022 SN - 978-1-6654-5985-3 U6 - https://doi.org/10.1109/SOCC56010.2022.9908103 SP - 1 EP - 6 PB - IEEE ER - TY - JOUR A1 - Kriegl, Raphael A1 - Kravanja, Gaia A1 - Hribar, Luka A1 - Čoga, Lucija A1 - Drevenšek‐Olenik, Irena A1 - Jezeršek, Matija A1 - Kalin, Mitjan A1 - Shamonin (Chamonine), Mikhail T1 - Microstructured Magnetoactive Elastomers for Switchable Wettability JF - Polymers N2 - We demonstrate the control of wettability of non-structured and microstructured magnetoactive elastomers (MAEs) by magnetic field. The synthesized composite materials have a concentration of carbonyl iron particles of 75 wt.% (≈27 vol.%) and three different stiffnesses of the elastomer matrix. A new method of fabrication of MAE coatings on plastic substrates is presented, which allows one to enhance the response of the apparent contact angle to the magnetic field by exposing the particle-enriched side of MAEs to water. A magnetic field is not applied during crosslinking. The highest variation of the contact angle from (113 ± 1)° in zero field up to (156 ± 2)° at about 400 mT is achieved in the MAE sample with the softest matrix. Several lamellar and pillared MAE structures are fabricated by laser micromachining. The lateral dimension of surface structures is about 50 µm and the depth varies between 3 µm and 60 µm. A systematic investigation of the effects of parameters of laser processing (laser power and the number of passages of the laser beam) on the wetting behavior of these structures in the absence and presence of a magnetic field is performed. In particular, strong anisotropy of the wetting behavior of lamellar structures is observed. The results are qualitatively discussed in the framework of the Wenzel and Cassie-Baxter models. Finally, directions of further research on magnetically controlled wettability of microstructured MAE surfaces are outlined. The obtained results may be useful for the development of magnetically controlled smart surfaces for droplet-based microfluidics. Y1 - 2022 U6 - https://doi.org/10.3390/polym14183883 N1 - Corresponding authors: Raphael Kriegl und Mikhail Shamonin VL - 14 IS - 18 SP - 1 EP - 21 PB - MDPI ER - TY - JOUR A1 - Nadzharyan, Timur A. A1 - Shamonin (Chamonine), Mikhail A1 - Kramarenko, Elena Yu T1 - Theoretical Modeling of Magnetoactive Elastomers on Different Scales: A State-of-the-Art Review JF - Polymers N2 - A review of the latest theoretical advances in the description of magnetomechanical effects and phenomena observed in magnetoactive elastomers (MAEs), i.e., polymer networks filled with magnetic micro- and/or nanoparticles, under the action of external magnetic fields is presented. Theoretical modeling of magnetomechanical coupling is considered on various spatial scales: from the behavior of individual magnetic particles constrained in an elastic medium to the mechanical properties of an MAE sample as a whole. It is demonstrated how theoretical models enable qualitative and quantitative interpretation of experimental results. The limitations and challenges of current approaches are discussed and some information about the most promising lines of research in this area is provided. The review is aimed at specialists involved in the study of not only the magnetomechanical properties of MAEs, but also a wide range of other physical phenomena occurring in magnetic polymer composites in external magnetic fields. KW - magnetodeformation KW - magnetorheological effect KW - mechanical properties KW - magnetic particles KW - theoretical modeling KW - magnetorheological elastomersn KW - magnetoactive elastomers Y1 - 2022 U6 - https://doi.org/10.3390/polym14194096 VL - 14 IS - 19 SP - 1 EP - 42 PB - MDPI ER - TY - CHAP A1 - Pozzobon, Enrico A1 - Renner, Sebastian A1 - Mottok, Jürgen A1 - Matoušek, Václav T1 - An optimized Bitsliced Masked Adder for ARM Thumb-2 Controllers T2 - 27th International Conference on Applied Electronics (AE): Sep 6, 2022 - Sep 7, 2022, Pilsen, Czech Republic N2 - The modular addition is used as a non-linear operation in ARX ciphers because it achieves the requirement of introducing non-linearity in a cryptographic primitive while only taking one clock cycle to execute on most modern architectures. This makes ARX ciphers especially fast in software implementations, but comes at the cost of making it harder to protect against side-channel information leakages using Boolean masking: the best known 2-shares masked adder for ARM Thumb micro-controllers takes 83 instructions to add two 32-bit numbers together. Our approach is to operate in bitsliced mode, performing 32 additions in parallel on a 32-bit microcontroller. We show that, even after taking into account the cost of bitslicing before and after the encryption, it is possible to achieve a higher throughput on the tested ciphers (CRAX and ChaCha20) when operating in bitsliced mode. Furthermore, we prove that no first-order information leakage is happening in either simulated power traces and power traces acquired from real hardware, after sufficient countermeasures are put into place to guard against pipeline leakages. KW - ARM Thumb KW - bitsliced KW - side-channel KW - Boolean masking Y1 - 2022 U6 - https://doi.org/10.1109/AE54730.2022.9919884 PB - IEEE ER - TY - CHAP A1 - Wetzel, Daniel A1 - Reindl, Andrea A1 - Meier, Hans A1 - Niemetz, Michael A1 - Farmbauer, Michael T1 - A Customized Python Interface for Windows OS for a Low Budget USB-to-CAN-Adapter T2 - International Conference on Electrical, Computer and Energy Technologies (ICECET 2022): 20-22 July 2022, Prague, Czech Republic N2 - Over the last three decades, the Controller Area Network (CAN) has become the dominant communication in embedded systems. Especially for automotive systems it offers advantages including high robustness, low error rate and high reliability combined with low power consumption. Therefore, learning the basics of this bus system is substantial in this field. Nowadays, various media about the functionality and use of CAN exist which make it easy to read into the topic. But often, theory alone is not sufficient. To deepen the understanding, practical implementation contributes significantly. However, affordable and easy-to-use CAN devices for training purposes are scarce. Existing equipment can be divided into expensive professional devices, which have many functions and inexpensive ones for hobbyists, which require difficult configurations. Therefore, a practical solution is a low-budget device equipped with an overlay which deals with the time consuming configurations. This paper covers the development of a python interface for a purchasable cost effective CAN device for Windows OS. The intention is to create an easy-to-use program that enables beginners to get in touch with CAN and collect practical experience. At the start, a brief explanation of the CAN functionality is given. After that, we introduce the hardware used in this project. Next, the software part covers the development of the interface and the integration of this interface into python-can. Furthermore, a virtual playground is introduced for testing purposes. Also, to demonstrate the functionality of the interface, a test program is executed in conjunction with a logic analyzer. KW - Controller area network KW - User Interface KW - USB to CAN KW - Windows KW - python-CAN Y1 - 2022 SN - 978-1-66547-087-2 U6 - https://doi.org/10.1109/ICECET55527.2022.9872574 PB - IEEE CY - Piscataway, NJ, USA ER - TY - JOUR A1 - Fuhrmann, Thomas T1 - Spherical lens aberration minimization method for short-range free-space light transmission JF - Optical Engineering N2 - Spherical aberrations of lenses lead to increased spot radii on the focal plane. Several methods, such as optimizing thickness and radii or building lens groups, are known to minimize these spherical aberrations. Here, an innovative method for spherical aberration minimization is introduced; it can be used for short-range free-space optical communication systems, such as unit power afocal relay trains, lens waveguides, and periodic lens systems. This spherical aberration compensation principle is based on the combination of two identical spherical convex lenses at an optimal distance. Due to the higher refractive power for rays with an larger axis distance, rays from the outer area of the first lens intersect the inner area of the second lens, and vice versa. With this setup, the radial refractive power deviation of the two lenses compensate each other. Analytic calculations and numerical simulations are done to confirm this behavior, and measurements using two symmetric spherical lenses with polymer optical fibers as light feed confirm the calculations. Simulations and measurements show a very good matching behavior except for an unknown systematic error. At a lens distance of 300 mm, the optical attenuation decreased by ∼2 dB compared with a very small lens distance. This leads to the conclusion that this proposed spherical aberration minimization method works as theoretically predicted. KW - Monochromatic aberrations KW - Signal attenuation KW - Spherical lenses KW - Polymer optical fibers KW - Monte Carlo methods KW - Free space optics KW - Optical testing KW - Distance measurement KW - Optical engineering KW - Optical simulations Y1 - 2022 U6 - https://doi.org/10.1117/1.OE.61.8.085101 SN - 1560-2303 SN - 0036-1860 SN - 0091-3286 VL - 61 IS - 8 PB - SPIE CY - Bellingham, Wash. ER - TY - CHAP A1 - Sefl, Ondrej A1 - Prochazka, Radek A1 - Haller, Rainer A1 - Monkman, Gareth J. T1 - Alternative Approach to Optical Detection of Partial Discharges in Air T2 - 2021 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP): 12-15 Dec. 2021, Vancouver, BC, Canada N2 - This article compares the standard electrical method of partial discharge detection with a novel optical detection method based on silicon photomultipliers. A third, complementary, single-loop antenna method is added to represent the ultra-high frequency method commonly used in gas-insulated switchgear/lines. A trio of air-insulated electrode designs that simulate the fundamental fault/discharge types in gaseous insulation (protrusion – corona discharge, floating conductive particle, surface discharges) are employed. Phase-resolved partial discharge activity patterns are compiled for each electrode design. The patterns are analyzed using spatial statistics and the interpretation of the obtained data trends explained by means of an example. Ultimately, the consistency and reliability of discharge detection by the optical methods for each fault/discharge type are evaluated, and suggestions for improvement are made. KW - gas insulated switchgear KW - loop antennas KW - partial discharges KW - photomultipliers KW - reliability KW - statistical analysis KW - surface discharges Y1 - 2021 SN - 978-1-6654-1907-9 U6 - https://doi.org/10.1109/CEIDP50766.2021.9705350 SN - 2576-2397 SP - 324 EP - 327 PB - IEEE ER - TY - JOUR A1 - Schmid, Michael A1 - Fritz, Florian A1 - Mottok, Jürgen T1 - Fine-grained parallelism framework with predictable work-stealing for real-time multiprocessor systems JF - Journal of Systems Architecture N2 - Lately, parallel task models have received much attention in the development of real-time multiprocessor systems, as they allow highly compute-intensive tasks to have shorter deadlines which is very much required in modern reactive systems. However, missing modularity and portability can make parallel programming a cumbersome endeavor. As a consequence, compute-intensive sectors in the desktop and server segment have relied on parallelism frameworks such as Intel Threading Building Blocks, Cilk and OpenMP. These parallelism frameworks, however, are optimized for decent average case performance and consequently, do not meet the strict requirements imposed by real-time systems. In this paper, we present a proof-of-concept parallelism framework which was implemented in particular for soft real-time systems and having tight timing and safety requirements of such critical systems in mind. The proposed runtime system implements static memory allocation in a work-stealing environment that conforms to the strict space and tight probabilistic time bounds of work-stealing schedulers. Furthermore, we evaluate the performance of this framework by conducting multiprogrammed benchmarks on a real-time embedded multicore architecture. Y1 - 2022 U6 - https://doi.org/10.1016/j.sysarc.2022.102393 N1 - Corrigendum: https://www.sciencedirect.com/science/article/pii/S1383762123000528?via%3Dihub VL - 124 IS - March PB - Elsevier ER - TY - CHAP A1 - Eberhart, Philip A1 - Chung, Tek Shan A1 - Haumer, Anton A1 - Kral, Christian T1 - Open Source Library for the Simulation of Wind Power Plants T2 - Proceedings of the 11th International Modelica Conference, Versailles, France, September 21-23, 2015 N2 - This paper presents the new open source Modelica libraryWindPowerPlants. For the economic assessment of either a wind power plant or an entire wind park, the accurate prediction of the energy output is essential. Such prediction is usually performed by means of calculations based on statistical wind data. The proposed WindPowerPlants library is capable of assessing the energy output both for statistical and real wind data based on time domain simulations. In the presented version of the library wind turbine models are modeled with pitch control. The generator models have variable speed and an optional connector to the mains. The entire library is based on power balance conditions and losses are fully neglected. Yet, the library can be extended towards more detailed models considering different types of losses. The structure and components of the library are presented. Simulations examples are shown and compared with reference data. The applicability of the proposed WindPowerPlants library is demonstrated and possible enhancements are discussed. KW - variable speed KW - pitch control KW - Wind power pants KW - energy KW - statistical wind data KW - power Y1 - 2015 U6 - https://doi.org/10.3384/ecp15118929 SP - 929 EP - 936 CY - Linköping ER - TY - JOUR A1 - Setzpfandt, Frank A1 - Sohler, Wolfgang A1 - Schiek, Roland A1 - Pertsch, Thomas T1 - Nonlinear coupling in discrete optical waveguide arrays with quadratic nonlinearity JF - Physical Review A N2 - We demonstrate nonlinear coupling in a discrete optical system. This is achieved in waveguide arrays with quadratic nonlinearity, where the symmetries of the nonlinearly interacting waveguide modes are used to suppress the usually dominating nonlinear effects within individual waveguides. We derive a mathematical model to describe the nonlinear coupling in such waveguide arrays and show experimentally the profound effects of this nonlinear coupling mechanism on second-harmonic generation. KW - BLOCH OSCILLATIONS KW - DYNAMICS KW - LIQUID-CRYSTALS KW - PHOTONIC LATTICES KW - PROPAGATION KW - SOLITONS Y1 - 2015 U6 - https://doi.org/10.1103/PhysRevA.92.043832 VL - 92 IS - 4 PB - American Physical Society ER - TY - CHAP A1 - Grauvogl, Dominik A1 - Krabinski, Jeffrey A1 - Stauder, Peter A1 - Hopfensperger, Bernhard A1 - Gerling, Dieter T1 - NVH Comparison of a Novel Wound Field Synchronous Machine with Magnetic Asymmetry with a PSM for a HV Electric Drive T2 - 2021 JSAE Annual Congress (Spring) Proceedings; online meeting (No.76-21) N2 - This paper shows how magnetic noises can be reduced with a wound field synchronous machine (WFSM) with magnetic asymmetry compared to a permanent magnet synchronous machine (PSM), operating at base speed range and full load. In order to reproduce a real noise behavior, the two rotor types are operated in a complete electric drive unit (EDU) consisting of an electric motor, gearbox, inverter and overall housing. In the concept study, the noise characteristics of the two electric machines is evaluated and compared via mechanical finite element method (FEM) simulations using the equivalent radiated power (ERP) level and Campbell diagrams. Furthermore, it is shown that critical frequency orders can already be identified by the analysis of the magnetic force density from the electromagnetic design without computationally intensive ERP calculations. In this context, the ERP investigations have shown that the unique feature of the magnetically asymmetric WFSM is the reduction of the slot harmonics. At the current state of the art, the slot harmonics can only be reduced with a rotor skewing. The disadvantage of this is a reduction in performance and a more expensive production. It is also remarkable that the magnetic asymmetry reduces the slot harmonics more than the rotor skewing in the PSM. In addition, both machines are still considered with a short-pitched stator winding to optimize the overall noise level by reducing the 24th frequency order. KW - Elektroantrieb KW - Synchronmaschine KW - traction drive system KW - NVH KW - e-axle KW - magnetic asymmetry Y1 - 2021 UR - https://tech.jsae.or.jp/paperinfo/en/content/p202101.343/ PB - JSAE ER - TY - CHAP A1 - Mucha, Matthias A1 - Mottok, Jürgen A1 - Krämer, Stefan T1 - Estimation of Worst Case Response Time Boundaries in Multi-Core Real-Time Systems T2 - 2017 International Conference on Applied Electronics (AE), 5-6 Sept. 2017, Pilsen N2 - We address a novel probabilistic approach to estimate the Worst Case Response Time boundaries of tasks. Multi-core real-time systems process tasks in parallel on two or more cores. Tasks in our contribution may preempt other tasks, block tasks with semaphores to access global shared resources, or migrate to another core. The depicted task behavior is random. The shape of collected response times of a task within a processing time is multimodal. Extreme Value approaches need unimodal response time distributions to estimate the Worst Case Response Time of tasks. The new proposed method derives a set of three task set shapes from the source task set. It is used to minimize the uncertainty of random task behavior by maximizing the coverage of possible Worst Case Response Times. The case study evaluates the new proposed estimation method by the use of dynamically generated random tasks with varying task properties. Y1 - 2017 SN - 978-80-261-0641-8 U6 - https://doi.org/10.23919/ae.2017.8053598 SN - 1803-7232 SP - 1 EP - 6 PB - IEEE ER - TY - CHAP A1 - Kraus, Hermann A1 - Brückl, Oliver ED - Schulz, Detlef T1 - Concept for the Use of an Automated Network-Planning in the Distribution Grid Level with Coordination of Various Grid Expansion Measures T2 - NEIS 2019 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg 19.09.2019 - 20.09.2019 N2 - In this thesis, a concept for the automated use of network planning processes, which is part of the decision support system developed in the framework of the EU project CrossEnergy, is presented. This publication focuses on the automatic processing of input data and subsequent network modeling as well as the coordination of network extension measures for the systematic solution of static voltage and current problems. Different variants are calculated in order to be able to compare the design technologies. KW - Eingabedaten KW - Entscheidungsunterstützungssystem KW - Konstruktionstechnik KW - Netzausbau KW - Netzmodell KW - Spannung (elektrisch) Y1 - 2019 UR - http://www.vde-verlag.de/proceedings-de/565152022.html SN - 978-3-8007-5152-5 SP - 161 EP - 165 ER - TY - JOUR A1 - Dillinger, Andrea Elisabeth A1 - Weber, Gregor R. A1 - Mayer, Matthias A1 - Schneider, Magdalena A1 - Göppner, Corinna A1 - Ohlmann, Andreas A1 - Shamonin (Chamonine), Mikhail A1 - Monkman, Gareth J. A1 - Fuchshofer, Rudolf A1 - Keller, Kate A1 - Lozano, Diana C. A1 - Clark, Abbot T1 - CCN2/CTGF-A Modulator of the Optic Nerve Head Astrocyte JF - Frontiers in cell and developmental biology (Front Cell Dev Biol.) N2 - In primary open-angle glaucoma (POAG), a neurodegenerative disease of the optic nerve (ON) and leading cause of blindness, the optic nerve head (ONH) undergoes marked structural extracellular matrix (ECM) changes, which contribute to its permanent deformation and to degeneration of ON axons. The remodeling process of the ECM causes changes in the biomechanical properties of the ONH and the peripapillary sclera, which is accompanied by an increased reactivity of the resident astrocytes. The molecular factors involved in the remodeling process belong to the Transforming growth factor (TGF)-β superfamily, especially TGF-β2. In previous publications we showed that TGF-β2 induced ECM alterations are mediated by Cellular Communication Network Factor (CCN)2/Connective Tissue Growth Factor (CTGF) and recently we showed that CCN2/CTGF is expressed by astrocytes of the ON under normal conditions. In this study we wanted to get a better understanding of the function of CCN2/CTGF under normal and pathologic conditions. To this end, we analyzed the glial lamina and peripapillary sclera of CCN2/CTGF overexpressing mice and studied the effect of CCN2/CTGF and increasing substratum stiffness on murine ON astrocytes in vitro. We observed enhanced astrocyte reactivity in the ONH, increased ECM protein synthesis in the peripapillary sclera and increased Ccn2/Ctgf expression in the ONH during the pathologic development in situ. CCN2/CTGF treatment of primary murine ON astrocytes induced a higher migration rate, and increase of ECM proteins including fibronectin, elastin and collagen type III. Furthermore, the astrocytes responded to stiffer substratum with increased glial fibrillary acidic protein, vimentin, actin and CCN2/CTGF synthesis. Finally, we observed the reinforced appearance of CCN2/CTGF in the lamina cribrosa of glaucomatous patients. We conclude that reactive changes in ONH astrocytes, induced by the altered biomechanical characteristics of the region, give rise to a self-amplifying process that includes increased TGF-β2/CCN2/CTGF signaling and leads to the synthesis of ECM molecules and cytoskeleton proteins, a process that in turn augments the stiffness at the ONH. Such a scenario may finally result in a vicious circle in the pathogenesis of POAG. The transgenic CTGF-overexpressing mouse model might be an optimal model to study the chronic pathological POAG changes in the ONH. KW - astrocytes KW - extracellar matrix KW - glaucoma KW - glial lamina KW - growth factors KW - optic nerve KW - stiffness Y1 - 2022 U6 - https://doi.org/10.3389/fcell.2022.864433 VL - 10 PB - frontiers ER - TY - JOUR A1 - Kovalev, Alexander A1 - Belyaeva, Inna A. A1 - von Hofen, Christian A1 - Gorb, Stanislav A1 - Shamonin (Chamonine), Mikhail T1 - Magnetically Switchable Adhesion and Friction of Soft Magnetoactive Elastomers JF - Advanced Engineering Materials N2 - Herein, the effect of an applied moderate (~240 mT) magnetic field on the work of adhesion (WoA) of mechanically soft (the shear modulus ~10 kPa) magnetoactive elastomer (MAE) samples with two different mass fractions (70 and 80 wt%) of carbonyl iron powder (CIP) is concerned. The unfilled elastomer sample is used for comparison. Due to some sedimentation of filling particles, the concentration of inclusions in thin (~10 μm) subsurface layers is different. It is shown that the WoA increases (up to 1.8-fold) on the particle-enriched side (PES) in the magnetic field and its value is higher for higher filler concentration. On the particle-depleted side (PDS), WoA does not depend on particle concentration and on the magnetic field. Adhesion and friction are coupled in MAEs. No statistically significant difference in the friction coefficient, determined from the extended Amontons´ law, depending on sample side, CIP concentration, or presence of magnetic field is found. However, the PDS in the magnetic field demonstrates significantly higher critical shear stress compared to that for the PES or PDS in the absence of magnetic field. Correlations between different surface properties are discussed. Obtained results are useful for the development of magnetically controllable soft robots. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-45283 N1 - Corresponding authors: Stanislav Gorb und Mikhail Shamonin VL - 24 IS - 10 SP - 1 EP - 8 PB - WILEY-VCH ER - TY - JOUR A1 - Glavan, Gašper A1 - Belyaeva, Inna A. A1 - Shamonin (Chamonine), Mikhail T1 - Multiferroic Cantilevers Containing a Magnetoactive Elastomer: Magnetoelectric Response to Low-Frequency Magnetic Fields of Triangular and Sinusoidal Waveform JF - Sensors N2 - In this work, multiferroic cantilevers comprise a layer of a magnetoactive elastomer (MAE) and a commercially available piezoelectric polymer-based vibration sensor. The structures are fixed at one end in the horizontal plane and the magnetic field is applied vertically. First, the magnetoelectric (ME) response to uniform, triangle-wave magnetic fields with five different slew rates is investigated experimentally. Time and field dependences of the generated voltage, electric charge, and observed mechanical deflection are obtained and compared for four different thicknesses of the MAE layer. The ME responses to triangular and sinusoidal wave excitations are examined in contrast. Second, the ME response at low frequencies (≤3 Hz) is studied by the standard method of harmonic magnetic field modulation. The highest ME coupling coefficient is observed in the bias magnetic field strength of ≈73 kA/m and it is estimated to be about 3.3 ns/m (ME voltage coefficient ≈ 25 V/A) at theoretically vanishing modulation frequency (f→0 Hz). Presented results demonstrate that the investigated heterostructures are promising for applications as magnetic-field sensors and energy harvesting devices. KW - magnetoactive elastomer KW - piezoelectric polymer KW - multilayer cantilever KW - direct magnetoelectric effect KW - magnetic field sensing Y1 - 2022 U6 - https://doi.org/10.3390/s22103791 N1 - Corresponding authors: Gašper Glavan und Mikhail Shamonin Veröffentlichtes Datenset: https://doi.org/10.5281/zenodo.14651784 VL - 22 IS - 10 SP - 1 EP - 17 PB - MDPI CY - Basel ER - TY - CHAP A1 - Zheng, Jihong A1 - Fuhrmann, Thomas A1 - Xu, Boqing A1 - Schreiner, Rupert A1 - Jia, Hongzhi A1 - Zhang, Wei A1 - Wang, Ning A1 - Seebauer, Gudrun A1 - Zhu, Jiyan T1 - Curriculum design and German student exchange for Sino-German Bachelor program majored in optoelectronics engineering T2 - 14th Conference on Education and Training in Optics and Photonics (ETOP 2017), 29-31.05.2017, Hangzhou, China, 29-31.05.2017 N2 - Different higher education backgrounds in China and Germany led to challenges in the curriculum design at the beginning of our cooperative bachelor program in Optoelectronics Engineering. We see challenges in different subject requirements from both sides and in the German language requirements for Chinese students. The curriculum was optimized according to the AS IIN criteria, which makes it acceptable and und erstandable by both countries. German students are integrated into the Chinese class and get the sa me lectures like their Chinese colleagues. Intercultural and curriculum challenges are successfully solved. The results are summarized to provide an example for other similar international programs. KW - cooperative bachelor program KW - optoelectronics KW - microsystems KW - student exchange Y1 - 2017 U6 - https://doi.org/10.1117/12.2269574 PB - SPIE ER - TY - JOUR A1 - Sorokin, Vladislav V. A1 - Stepanov, Gennady V. A1 - Shamonin (Chamonine), Mikhail A1 - Monkman, Gareth J. A1 - Khokhlov, Alexei R. A1 - Kramarenko, Elena Yu T1 - Hysteresis of the viscoelastic properties and the normal force in magnetically and mechanically soft magnetoactive elastomers: Effects of filler composition, strain amplitude and magnetic field JF - Polymer N2 - Hysteresis in dynamic modulus, loss factor and normal forces of magnetoactive elastomers (MAEs) comprising various proportions of small (3-5 mu m) and large (50-60 mu m) ferromagnetic particles are experimentally studied using dynamic torsion performed at a fixed oscillation frequency in varying DC magnetic fields. It is shown that hysteresis is a characteristic feature of MAEs observed both under increasing/decreasing magnetic field strength and increasing/decreasing strain amplitude. This hysteresis is attributed to the specific rearrangement of the magnetic filler network under simultaneously applied magnetic field and shear deformation. Rheological properties of the magnetic filler network formed in the magnetic field and, therefore, the rheological properties of MAEs depend strongly on the filler composition and the magnetic field magnitude. Larger magnetic particles and higher magnetic fields provide stronger magnetic networks. Both factors result in the extension of the linear viscoelastic regime to larger strain amplitudes and lead to higher values of shear storage and loss moduli. It is found that the hysteresis width maximises at an intermediate magnetic field where it is attributed to the balance between elastic and magnetic particle interactions. This is apparently where the most significant restructuring of the magnetic network occurs. The hysteresis width decreases with increasing fraction of large particles in the magnetic filler. The loss factor grows significantly when the magnetic network is physically broken by large strains gamma > 1%. A huge (more than one order of magnitude) increase of normal force at maximum magnetic field strengths is observed. It is predicted that any physical quantity depending on the internal structuring of the magnetic filler should demonstrate hysteresis either with a changing magnetic field and constant deformation amplitude or under variable deformation in a constant magnetic field. (C) 2015 Elsevier Ltd. All rights reserved. KW - BEHAVIOR KW - COMPRESSION KW - Dynamic modulus KW - GELS KW - hysteresis KW - Magnetorheological elastomers KW - magnetostriction KW - MODULUS KW - PARTICLES KW - POLYMER COMPOSITES KW - shear Y1 - 2015 U6 - https://doi.org/10.1016/j.polymer.2015.08.040 VL - 76 SP - 191 EP - 202 PB - Elsevier ER - TY - CHAP A1 - Setzpfandt, Frank A1 - Schiek, Roland A1 - Sohler, Wolfgang A1 - Pertsch, Thomas T1 - Nonlinear Nearest-Neighbor Coupling in Quadratic Waveguide Arrays T2 - Nonlinear Optics : Proceedings Nonlinear Optics 26-31 July 2015, Kauai, Hawaii, United States N2 - We investigate nonlinear coupling between neighboring waveguides in waveguide arrays with second-order nonlinearity. Using mode symmetries to suppress local nonlinearities, we experimentally show the profound effect of such nonlinear nearest-neighbor interactions on second-harmonic generation. Y1 - 2015 SN - 978-1-55752-001-2 U6 - https://doi.org/10.1364/nlo.2015.nm3b.6 PB - OSA CY - Washington, D.C. ER - TY - CHAP A1 - Haumer, Anton A1 - Kral, Christian T1 - Enhancements of Electric Machine Models: The EMachines Library T2 - Proceedings of the 11th International Modelica Conference, Versailles, France, September 21-23, 2015 N2 - Transient models of multi phase electric machines are already implemented in the Modelica Standard Library (MSL). However, advanced effects like saturation and skin effect are not taken into account. As an extension to the MSL models, the new EMachines library is presented. This package will be released as a supplemental library to the commercial EDrives library. The particular focus of this paper is on the deep bar effect of induction machines. A comparison of simulation results demonstrates the influence of the skin effect on the operational behavior of the machines. At the end of this publication further developments of the EMachines library will be outlined. KW - multi phase electric machines KW - induction machines KW - squirrel cage KW - deep bar effect KW - skin effect Y1 - 2015 U6 - https://doi.org/10.3384/ecp15118509 VL - 118 SP - 509 EP - 515 PB - Linköping University Electronic Press ER - TY - CHAP A1 - Studt, Reimer A1 - Weiß, Florian A1 - Mottok, Jürgen A1 - Weiss, Florian A1 - Mottok, Jürgen T1 - An engineering approach to developing lecture material for new study courses T2 - 2014 IEEE Global Engineering Education Conference (EDUCON), 3-5 April 2014, Istanbul, Turkey N2 - Professional software development is a complex task with many inputs and a complex output. In order to handle complex topics as software or complex engineering projects, structured processes as the V-model or iterative development processes exist. Similarly, the development of a software engineering lecture is a task with many inputs, and a complex output. A structured and methodological approach to the development of a lecture is presented, which applies the same principles as used in the development of software. KW - biomedical engineering KW - competence model KW - computer science education KW - Education KW - Insulin KW - Knowledge engineering KW - lecture development KW - Materials KW - Software KW - Software engineering KW - Unified modeling language Y1 - 2014 U6 - https://doi.org/10.1109/EDUCON.2014.6826153 SP - 592 EP - 597 PB - IEEE ER - TY - CHAP A1 - Setzpfandt, Frank A1 - Solntsev, Alexander S. A1 - Titchener, James A1 - Wu, Che Wen A1 - Xiong, Chunle A1 - Pertsch, Thomas A1 - Schiek, Roland A1 - Neshev, Dragomir N. A1 - Sukhorukov, Andrey A. T1 - Optically tunable entangled photon state generation in a nonlinear directional coupler T2 - CLEO: QELS_Fundamental Science 2015, San Jose, California, United States, 10-15 May 2015 N2 - We propose and experimentally demonstrate an all-optically tunable biphoton quantum light source using a nonlinear directional coupler. The source can generate high-fidelity N00N states, completely split states, and states with variable degrees of entanglement. Y1 - 2015 SN - 978-1-55752-968-8 U6 - https://doi.org/10.1364/cleo_qels.2015.fth4d.3 PB - OSA CY - Washington, D.C. ER - TY - CHAP A1 - Schmidt, Hans-Peter A1 - Fuchs, Andreas A1 - Fuchs, Stefan T1 - Simultaneous contact less charging of multiple electric vehicles: Contact less power and data transfer for multiple distributed loads T2 - 2014 4th International Electric Drives Production Conference ( 30 Sept.-1 Oct. 2014, Nuremberg, Germany N2 - A design of a 3-phase inductive power and data transfer for multiple stationary loads is proposed. It focuses on stable load voltages while minimizing electromagnetic interference. Loads are contactless charging units of electric vehicles at car parks. Physical properties of the inductive couplers are modelled via 3-D FEM and lumped parameters are used for system studies. Design principles are verified at laboratory scale with a purpose built test stand. KW - charging infrastructure KW - Coils KW - contact less charging KW - Couplers KW - Couplings KW - Data transfer KW - Electric vehicles KW - electro mobility KW - Feeds KW - multiple stationary loads KW - Windings Y1 - 2014 U6 - https://doi.org/10.1109/EDPC.2014.6984435 SP - 1 EP - 3 PB - IEEE ER - TY - CHAP A1 - Tao, Ye A1 - Liu, Guozhu A1 - Mottok, Jürgen A1 - Hackenberg, Rudolf A1 - Hagel, Georg A1 - Mottok, Jürgen T1 - Just-in-Time Teaching in software engineering: A Chinese-German empirical case study T2 - 2014 IEEE Global Engineering Education Conference (EDUCON), 3-5 April 2014, Istanbul, Turkey N2 - Learning centered teaching becomes an important factor in a global perspective of learning software engineering. The Just-in-Time Teaching approach is used in a Chinese-German empirical case study. In a one year terminated project we will analyze the performance of our students in an active learning scenario with Just-in-Time Teaching and Peer Instruction. We will contribute an inter-cultural comparison of achieved competencies by student’s self-assessment and teacher’s observation. KW - Activating Learning KW - Blended Learning KW - Conferences KW - Educational institutions KW - E-Learning KW - ISO Standards KW - JiTT KW - Just-in-Time Teaching KW - Materials KW - Practical Learning KW - Software KW - Software engineering Y1 - 2014 U6 - https://doi.org/10.1109/EDUCON.2014.6826220 SP - 983 EP - 986 PB - IEEE ER - TY - CHAP A1 - Schlal, Sebastian A1 - Wicke, Markus A1 - Zahner, Thomas A1 - Lang, Kurt-Jürgen T1 - Evaluation of thermal solder joint quality and thermal performance of PCBs by using standard measurement equipment T2 - 20th International Workshop on Thermal Investigations of ICs and Systems, 24-26 Sept. 2014, Greenwich, UK N2 - By using more powerful LEDs a good thermal management is becoming more and more important. Here usually the thermal interconnects have to be in focus. Therefore a simple and rapid measurement method for the thermal check of the solder joint in a high volume production is necessary. A standard thermal resistance measurement is very time consuming due to the calibration of each device. By using thermal characterized reference devices it is possible to skip the time consuming part. Furthermore, a simple methodology for evaluating the thermal performance of the various metal core PCB (MCPCB) materials and construction is required during development. In this paper we will present how we successfully demonstrated that this new method offers an opportunity to determine the thermal performance of a high power QFN LED on different types of isolated metal substrate (IMS) and with a standard SMU [1] (source measurement units). KW - Electrical resistance measurement KW - Light emitting diodes KW - Semiconductor device measurement KW - Soldering KW - standards KW - Thermal resistance Y1 - 2014 U6 - https://doi.org/10.1109/THERMINIC.2014.6972522 SP - 1 EP - 5 PB - IEEE ER - TY - CHAP A1 - Setzpfandt, Frank A1 - Solntsev, Alexander S. A1 - Titchener, James A1 - Wu, Che Wen A1 - Xiong, Chunle A1 - Pertsch, Thomas A1 - Schiek, Roland A1 - Neshev, Dragomir N. A1 - Sukhorukov, Andrey A. T1 - Optically Tunable Entangled Photon State Generation in a Nonlinear Directional Coupler T2 - Nonlinear Optics [Kauai, Hawaii 26-31 July 2015] N2 - We propose and experimentally demonstrate an all-optically tunable biphoton quantum light source using a nonlinear directional coupler. The source can generate high-fidelity N00N states, completely split states, and states with variable degrees of entanglement. Y1 - 2015 SN - 978-1-55752-001-2 U6 - https://doi.org/10.1364/nlo.2015.nw2a.4 IS - paper NW2A.4 PB - OSA CY - Washington, D.C. ER - TY - CHAP A1 - Hofmeister, Justus A1 - Krebs, Stefan A1 - Schickhuber, Gerald A1 - Scharfenberg, Georg T1 - Design and development of a Pico Hydro turbine system for the use in developing countries T2 - 2015 5th International Youth Conference on Energy (IYCE), 27-30 May 2015, Pisa, Italy N2 - In Sub-Saharan Africa less than 10% of the rural population has access to electricity [1]. Stand-alone power systems (SPS) can be a solution to the problem of the lack of electricity, which highlights challenges such as modules installation costs as well as the sufficient knowledge required for installing, maintaining and operating such systems. With this fact in mind, a 250 W Low Head turbine system was developed and optimized to have the advantage of the simplicity of installation and a construction from readily available materials. This design scores the electrical efficiency of 60%, reduces manufacturing unit coast to 130 € and takes into account the necessity of providing a clear and simple manual describing the manufacturing and installation. A better version of the load controller, using a microcomputer is under current development. Mounting of the system have been simplified to reduce the amount of construction material required to provide uninterrupted 230 V at 50 Hz AC or optional 12 V DC power supply. Current efforts aim on transferring the required mechanical and electrical knowledge for building, programming, installing and maintaining such system to schools in targeted countries. This project doesn’t only provide people in rural developing countries a gleam of hope to catch up with the developed countries, but also helps students to use their theoretical knowledge to realize practical applications. KW - Coils KW - Development Cooperation KW - Generators KW - Hydraulic turbines KW - Low Head KW - Pico Hydro KW - Propellers KW - Shafts KW - Synchronous Generator KW - Water Turbine KW - Windings Y1 - 2015 U6 - https://doi.org/10.1109/IYCE.2015.7180767 SP - 1 EP - 7 PB - IEEE ER - TY - CHAP A1 - Hopfensperger, Bernhard A1 - Daubner, Andreas A1 - Herrmann, Fabian A1 - Hopkins, Andrew A1 - Mellor, Phil T1 - Investigation of Shifted PWM Methods for a Dual Three-Phase System to Reduce Capacitor RMS Current T2 - PCIM Europe Digital Days 2020: International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management: 07.-08.07.2020, Online [proceedings] N2 - Mild hybrid automotive topologies containing a 48V high power (>15 kW) electric drive system demand a high integration of power electronics and electrical machine. A multi-phase motor winding topology helps to keep the per-phase operating currents to a reasonable level. Close integration and multi-phase system have led to a drive system with dual 3-phase systems supplied by a common 48V DC-link, which allows to shift PWM patterns for reduction of DC-link capacitor ripple current and size. This paper derives some basic rules for combinations of common PWM methods for dual 3-phase systems without magnetic cross-coupling. Experimental measurements verify simulated results. KW - Elektroantrieb KW - dual three phase system Y1 - 2020 UR - https://ieeexplore.ieee.org/document/9177989 SN - 978-3-8007-5245-4 SP - 124 EP - 131 PB - VDE-Verlag CY - Berlin, Offenbach ER - TY - CHAP A1 - Hofmann, Gerhard A1 - Scharfenberg, Georg T1 - Applicability of the ISO 26262 for functional safety for motorbikes T2 - 2014 International Conference on Applied Electronics, 9-10 Sept. 2014, Pilsen, Czech Republic N2 - This article deals with the question to what extent the automotive standard for functional safety ISO 26262 is also applicable to motorbikes. It examines thereby, on the one hand where to find comparable criteria between cars and motorbikes from the standpoint of functional safety, and, on the other hand, where differences between the automobile and the motorbike must be considered. It shows the extent to which the safety-related automotive standard is applicable to motorbikes. Furthermore, the differences are determined, which must lead to the consequence of a new “state of the art” and to a new standard for motorbikes. On the example of a light function the new MSIL classification gets applied. In this article, the motorbike is viewed as a whole. For the most parts the standard is also valid for scooters. KW - Automobiles KW - Automotive engineering KW - Functional Safety KW - ISO 26262 KW - ISO Standards KW - motorbike KW - Motorcycles KW - MSIL KW - safety Y1 - 2014 U6 - https://doi.org/10.1109/AE.2014.7011679 SP - 107 EP - 112 PB - IEEE ER - TY - JOUR A1 - Schoepe, Wilfried A1 - Hänninen, Risto A1 - Niemetz, Michael T1 - Breakdown of Potential Flow to Turbulence Around a Sphere Oscillating in Superfluid 4He Above the Critical Velocity JF - Journal of low temperature physics N2 - The onset of turbulent flow around an oscillating sphere in superfluid 4He is known to occur at a critical velocity where is the circulation quantum and is the oscillation frequency. But it is also well known that initially in a first up-sweep of the oscillation amplitude, can be considerably exceeded before the transition occurs, thus leading to a strong hysteresis in the velocity sweeps. The velocity amplitude where the transition finally occurs is related to the density of the remanent vortices in the superfluid. Moreover, at temperatures below ca. 0.5 K and in a small interval of velocity amplitudes between and a velocity that is about 2 % larger, the flow pattern is found to be unstable, switching intermittently between potential flow and turbulence. From time series recorded at constant temperature and driving force, the distribution of the excess velocities is obtained and from that the failure rate. Below 0.1 K we also can determine the distribution of the lifetimes of the phases of potential flow. Finally, the frequency dependence of these results is discussed. KW - Intermittent switching KW - LAMINAR KW - MICROSPHERE KW - Oscillatory flow KW - Quantum turbulence KW - Remanent vorticity KW - VIBRATING-WIRE Y1 - 2015 U6 - https://doi.org/10.1007/s10909-014-1265-7 VL - 178 SP - 383 EP - 391 PB - Springer Nature ER - TY - CHAP A1 - Schiek, Roland T1 - Self-phase modulation in lithium niobate waveguides T2 - 2014 International Conference Laser Optics, title=Self-phase modulation in lithium niobate waveguides, 30 June-4 July 2014, St. Petersburg, Russia N2 - Self-phase modulation in lithium niobate wave-guides with cascaded quadratic and cubic nonlinearities is characterized by comparison of amplitude and phase of input and output pulse envelopes and spectra. Cubic nonlinear susceptibility coefficients of lithium niobate were determined from the measured nonlinear phase shifts. KW - Frequency measurement KW - Frequency modulation KW - lithium niobate KW - nonlinear susceptibility KW - self-phase modulation KW - Wavelength measurement Y1 - 2014 U6 - https://doi.org/10.1109/LO.2014.6886403 PB - IEEE ER - TY - JOUR A1 - Räsänen, Esa A1 - Pulkkinen, Otto A1 - Virtanen, Tuomas A1 - Zollner, Manfred A1 - Hennig, Holger T1 - Fluctuations of hi-hat timing and dynamics in a virtuoso drum track of a popular music recording JF - PLoS ONE N2 - Long-range correlated temporal fluctuations in the beats of musical rhythms are an inevitable consequence of human action. According to recent studies, such fluctuations also lead to a favored listening experience. The scaling laws of amplitude variations in rhythms, however, are widely unknown. Here we use highly sensitive onset detection and time series analysis to study the amplitude and temporal fluctuations of Jeff Porcaro's one-handed hi-hat pattern in "I Keep Forgettin'"-one of the most renowned 16th note patterns in modern drumming. We show that fluctuations of hi-hat amplitudes and interbeat intervals (times between hits) have clear long-range correlations and short-range anticorrelations separated by a characteristic time scale. In addition, we detect subtle features in Porcaro's drumming such as small drifts in the 16th note pulse and non-trivial periodic two-bar patterns in both hi-hat amplitudes and intervals. Through this investigation we introduce a step towards statistical studies of the 20th and 21st century music recordings in the framework of complex systems. Our analysis has direct applications to the development of drum machines and to drumming pedagogy. KW - Humans KW - Models, Theoretical KW - Music Y1 - 2015 U6 - https://doi.org/10.1371/journal.pone.0127902 VL - 10 IS - 6 PB - PLOS ER - TY - CHAP A1 - Grothmann, Benjamin A1 - Poelsterl, Thomas A1 - Gerling, Dieter T1 - Online compensation of current sensor gain-faults for safety-relevant IPM-drives T2 - 2017 IEEE Transportation Electrification Conference and Expo (ITEC), 22-24 June 2017, Chicago, IL, USA N2 - Detection and compensation of current sensor gain-faults regardless of the operating-point is a crucial aspect for safety-relevant servo-drives. This paper presents and investigates a new direct phase-gain re-balancing methodology, especially suited for interior permanent magnet machine (IPM) drives mostly operating at low speed-ranges including standstill. The proposed model-based approach utilizes high-frequency signal-injection (HFI) to facilitate fast and persistent sensor monitoring for any operating state of the drive. No additional sensing hardware is required. Extraction of the HFI-phase-current response enables detection and immediate compensation of sensor gain-faults. Implementation aspects of the proposed concept are discussed thoroughly. Experimental results are presented to prove and investigate robustness, reliability and fault-tolerant performance. KW - Acoustic noise KW - Current measurement KW - Frequency synchronization KW - Hardware KW - Phase measurement KW - Signal to noise ratio KW - Torque Y1 - 2017 U6 - https://doi.org/10.1109/ITEC.2017.7993355 SP - 701 EP - 706 PB - IEEE ER - TY - JOUR A1 - Niemetz, Michael A1 - Hänninen, Risto A1 - Schoepe, Wilfried T1 - On the Transition from Potential Flow to Turbulence Around a Microsphere Oscillating in Superfluid 4He JF - Journal of low temperature physics N2 - The flow of superfluid around a translationally oscillating sphere, levitating without mechanical support, can either be laminar or turbulent, depending on the velocity amplitude. Below a critical velocity that scales as and is temperature independent below 1 K, the flow is laminar (potential flow). Below 0.5 K, the linear drag force is caused by ballistic phonon scattering that vanishes as until background damping, measured in the empty cell, becomes dominant for K. Increasing the velocity amplitude above leads to a transition from potential flow to turbulence, where the large turbulent drag force varies as . In a small velocity interval % above , the flow is unstable below 0.5 K, switching intermittently between both patterns. From time series recorded at constant temperature and driving force, the lifetimes of both phases are analyzed statistically. We observe metastable states of potential flow which, after a mean lifetime of 25 min, ultimately break down due to vorticity created by natural background radioactivity. The lifetimes of the turbulent phases have an exponential distribution, and the mean increases exponentially with . We investigate the frequency at which the vortex rings are shed from the sphere. Our results are compared with recent data of other authors on vortex shedding by moving a laser beam through a Bose-Einstein condensate. Finally, we show that our observed transition to turbulence belongs to the class of "supertransient chaos" where lifetimes of the turbulent states increase faster than exponentially. KW - Bose-Einstein condensates KW - Critical velocity KW - DYNAMICS KW - EINSTEIN CONDENSED GAS KW - HE-4 KW - HELIUM KW - LAMINAR KW - MK TEMPERATURES KW - ONSET KW - Oscillatory flow KW - Quantum turbulence KW - Superfluid helium KW - Vortex shedding Y1 - 2017 U6 - https://doi.org/10.1007/s10909-017-1745-7 VL - 187 IS - 3-4 SP - 195 EP - 220 PB - Springer Nature ER - TY - GEN A1 - Sterner, Michael T1 - Megathema Wasserstoff: Power-to-X im Kontext der Energiewende und des Klimaschutzes in Deutschland T2 - IRES Symposium, Berlin 18.11.2020 KW - Erneuerbare Energien KW - Wasserstoff KW - Klimaneutralität KW - Power-to-X KW - Energiewende KW - Sektorenkopplung Y1 - 2020 ER - TY - CHAP A1 - Grauvogl, Dominik A1 - Stauder, Peter A1 - Hopfensperger, Bernhard A1 - Gerling, Dieter T1 - Multiphysics Design of a Wound Field Synchronous Machine with Magnetic Asymmetry T2 - Proceedings of the 2021 IEEE International Electric Machines & Drives Conference (IEMDC): 17-20 May 2021, Hartford, CT, USA N2 - In this paper a multiphysics development method is used for designing a novel wound field synchronous machine of the future generation of high voltage traction drives. This method covers the domains of electromagnetics, the mechanical strength, thermal behavior and the magnetic noise. It is shown that the proposed novel asymmetric design with a circular flux barrier in combination with an asymmetric pole offset is fulfilling the requirements according to performance and torque ripple. A fatigue strength rotor mechanic concept is included. A hybrid cooling concept consisting of a water jacket cooled stator and air cooled rotor ensures the needed continuous power. Unacceptable noise levels are excluded by investigating the equivalent radiated power (ERP) level due to radial forces in the air gap. Finally, the multi-physical workflow resulted in a fully developed component with a high degree of maturity. KW - air cooling KW - wound field synchronous machine KW - cooling concept KW - fatigue limit KW - flux barrier Y1 - 2021 U6 - https://doi.org/10.1109/IEMDC47953.2021.9449564 ER - TY - CHAP A1 - Diehl, Andreas A1 - Wolff, Lilli A1 - Fuhrmann, Thomas A1 - Niemetz, Michael A1 - Mörtlbauer, Stefanie A1 - Dirnberger, Sandra T1 - Compact Freshmen Welcome Seminar for Engineering Students T2 - Procedia - Social and Behavioral Sciences N2 - The Faculty of Electrical Engineering and Information Technology of the OTH Regensburg developed and implemented a compact freshmen seminar for the afternoon of the first day of study. The intention of this seminar is to help the freshmen during their transition between school and study without losing lecture time in the first semester. The concept was tested with one small study group at the beginning of the summer semester 2015. To rate the impact of the seminar and to find aspects for continuous improvement an evaluation method was developed and used. Due to the good student resonance during the first run, this introduction seminar was held again in the winter semester 2015/16. It is planned to integrate this seminar as a regular session for all freshmen of the faculty curriculum and monitor the long-term effects of student motivation and success. KW - Engineering Education KW - Freshmen Seminar Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-31034 N1 - Corresponding author: Thomas Fuhrmann IS - 228 SP - 45 EP - 52 PB - Elsevier ER - TY - CHAP A1 - Blank, M. A1 - Brunner, Stefan A1 - Fuhrmann, Thomas A1 - Meier, Hans A1 - Niemetz, Michael T1 - Embedded Linux in engineering education T2 - 2015 IEEE Global Engineering Education Conference (EDUCON), 18-20 March 2015, Tallinn, Estonia N2 - With the availability of cost effective embedded Linux solutions and the increasing complexity of embedded devices because of growing calculation power and communication demand, Linux is getting increasingly interesting as an operating system for the design of embedded control solutions. This is the case for almost all technical applications in electrical engineering like energy distribution systems, high level communication, signal processing or industrial automation. In the engineering master courses at the OTH Regensburg, a lecture is offered introducing students to Linux with a strong focus on embedded applications. This paper describes the concept of the lecture including the laboratory set up and gives some examples of embedded Linux projects performed by students. KW - Engineering Education KW - Linux KW - Operating systems KW - Ports (Computers) KW - Universal Serial Bus KW - Vehicles KW - Wireless communication Y1 - 2015 U6 - https://doi.org/10.1109/EDUCON.2015.7095964 SP - 145 EP - 150 PB - IEEE ER - TY - CHAP A1 - Schneider, Michael A1 - Haumer, Anton A1 - Köckeis, Rupert T1 - Modelling and Simulation of the passive Structure of a 5-Axis-Milling Machine with rigid and flexible bodies for evaluating the static and dynamic behaviour T2 - Proceedings of the 12th International Modelica Conference, Prague, Czech Republic, May 15-17, 2017 N2 - Most of the mechanical simulations for industrial usage are done by finite element (FE-) analysis. Milling machines are mechatronic systems, combining electrical, mechanical and control components for machining certain materials. Modelica provides a powerful and strong tool to simulate different physical ares in one model. For this usage a mechanical model of a 5-Axis-Milling Machine is implemented with rigid and flexible bodies. Specific attention will be paid to which components can be modelled rigid without significant deviation in accordance to the real behaviour of the machine. Two classes of implementing flexible bodies in multi body systems are given by the flexible bodies Library, advantages and disadvantages of both classes will be evaluated. At the end a comparision of the static and dynamic behaviour of the passive structure of the model in contrast to a FE-analysis is given. KW - clay modelling KW - multibody system KW - Milling machine KW - flexible body Y1 - 2017 U6 - https://doi.org/10.3384/ecp17132389 SP - 389 EP - 395 PB - Linköping University Electronic Press ER - TY - CHAP A1 - Grimm, Alexander A1 - Haumer, Anton T1 - EMOTH The EMobility Library of OTH Regensburg T2 - Proceedings of the 12th International Modelica Conference, Prague, Czech Republic, May 15-17, 2017 N2 - The importance of E-Mobility is rapidly increasing, not only for private vehicle traffic but also for public transport. In and around Regensburg, Germany there are a lot of automotive companies. Therefore E-Mobility is an important topic in the curriculum of several courses of study at the East-Bavarian Technical University of Applied Sciences Regensburg (OTH). One Master of Applied Research student at OTH has chosen the topic to develop an open-source simulation tool for electric vehicles – the EMOTH Library – based on Modelica and to refine several aspects of the library during the one and a half year of the master course. After one semester, the basic version of the library is available and will be presented in this paper. Y1 - 2017 U6 - https://doi.org/10.3384/ecp17132285 SP - 285 EP - 290 PB - Linköping University Electronic Press ER - TY - JOUR A1 - Kalita, Viktor M. A1 - Snarskii, Andrei A. A1 - Shamonin (Chamonine), Mikhail A1 - Zorinets, Denis T1 - Effect of single-particle magnetostriction on the shear modulus of compliant magnetoactive elastomers JF - Physical review E N2 - The influence of an external magnetic field on the static shear strain and the effective shear modulus of a magnetoactive elastomer (MAE) is studied theoretically in the framework of a recently introduced approach to the single-particle magnetostriction mechanism [V. M. Kalita et al., Phys. Rev. E 93, 062503 (2016)]. The planar problem of magnetostriction in an MAE with magnetically soft inclusions in the form of a thin disk (platelet) having the magnetic anisotropy in the plane of this disk is solved analytically. An external magnetic field acts with torques on magnetic filler particles, creates mechanical stresses in the vicinity of inclusions, induces shear strain, and increases the effective shear modulus of these composite materials. It is shown that the largest effect of the magnetic field on the effective shear modulus should be expected in MAEs with soft elastomer matrices, where the shear modulus of the matrix is less than the magnetic anisotropy constant of inclusions. It is derived that the effective shear modulus is nonlinearly dependent on the external magnetic field and approaches the saturation value in magnetic fields exceeding the field of particle anisotropy. It is shown that model calculations of the effective shear modulus correspond to a phenomenological definition of effective elastic moduli and magnetoelastic coupling constants. The obtained theoretical results compare well with known experimental data. Determination of effective elastic coefficients in MAEs and their dependence on magnetic field is discussed. The concentration dependence of the effective shear modulus at higher filler concentrations has been estimated using the method of Pade approximants, which predicts that both the absolute and relative changes of the magnetic-field-dependent effective shear modulus will significantly increase with the growing concentration of filler particles. KW - BEHAVIOR KW - composites KW - DEPENDENCE KW - FERROGELS KW - MECHANICAL-PROPERTIES KW - MICROSTRUCTURE KW - Polymer KW - PURE SHEAR KW - RHEOLOGY KW - SENSITIVE ELASTOMERS Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevE.95.032503 VL - 95 IS - 3 PB - American Physical Society ER - TY - GEN A1 - Sterner, Michael A1 - Thema, Martin T1 - Technologies status and perspectives of Power-to-Gas in connection with seasonal underground storage T2 - European Workshop on Underground Energy Storage, Paris 07.11.2019 KW - Erneuerbare Energien KW - Klimaneutralität KW - Energiewende KW - Sektorenkopplung KW - Power-to-Gas Y1 - 2019 ER - TY - GEN A1 - Thema, Martin A1 - Bauer, Franz A1 - Sterner, Michael T1 - Power-to-Gas world status report T2 - International Renewable Energy Storage Conference, Düsseldorf 14.-16.03.2019 KW - Erneuerbare Energien, Klimaneutralität, Energiewende, Sektorenkopplung, Power-to-Gas KW - Power-to-Gas KW - Sektorenkopplung KW - Energiewende KW - Klimaneutralität Y1 - 2019 ER - TY - CHAP A1 - Wick, Michael A1 - Lindner, Gerhard A1 - Zimmer, Katja A1 - Schreiner, Rupert A1 - Fuhrmann, Thomas A1 - Seebauer, Gudrun A1 - Xu, Boqing A1 - Zheng, Jihong A1 - Wang, Ning ED - Liu, Xu ED - Zhang, Xi-Cheng T1 - German-Chinese cooperative Bachelor in engineering physics/optoelectronics T2 - 14th Conference on Education and Training in Optics and Photonics: ETOP 2017; Hangzhou, China 29.05.2017 - 31.05.2017 N2 - The University of Shanghai for Science and Technology (USST), the Coburg University of Applied Sciences and Arts (CUASA) and the OTH Regensburg, University of Applied Sciences (OTHR) established an English taught international cooperative bachelor program in the area of Engineering Physics/Optoelectronics. Students from China study their first four semesters at USST. They continue their studies in Germany for the last three semesters, including an internship and a bachelor thesis, graduating with a Chinese and a German bachelor degree. Students from Germany study their third and fourth semester at USST to gain international experience. While the first cohort of Chinese students is currently in Germany, the second cohort of German students is in Shanghai. Up to now the feedback regarding this study program is completely positive, thus it is planned to develop it further. Y1 - 2017 SN - 9781510613812 U6 - https://doi.org/10.1117/12.2269943 PB - SPIE ER - TY - CHAP A1 - Rösel, Birgit A1 - Köhler, Thomas T1 - First results of a new digitalized concept for teaching control theory as minor subject at a university of applied science T2 - 2018 IEEE Global Engineering Education Conference (EDUCON), 17-20 April 2018, Santa Cruz de Tenerife, Spain N2 - This paper presents a digitalized concept for teaching control theory as minor subject with an integrated approach for lectures, exercises and practical sessions and first results of the implementation at the department of electrical engineering at the OTH Regensburg. The concept uses activating methods like blended learning and possibilities of digitalization of teaching implementing Just in Time Teaching and Peer Instruction. The base of the new concept is the idea of constructive alignment. Furthermore this paper presents the feedback of the students along with an accompanying scientific research over several semesters. The data obtained from the presented module are compared with the data from other blended learning approaches in Germany. KW - Blended Learning KW - constructive alignment KW - Control theory KW - Electrical engineering KW - Electronic learning KW - Just in Time Teaching KW - Task analysis KW - taxonomy KW - teaching text Y1 - 2018 U6 - https://doi.org/10.1109/EDUCON.2018.8363217 SP - 118 EP - 125 PB - IEEE ER - TY - CHAP A1 - Fuhrmann, Thomas T1 - Motivation Centered Learning T2 - 2018 IEEE Frontiers in Education Conference (FIE), 3-6 Oct. 2018, San Jose, CA, USA N2 - This Research Work in Progress Paper evaluates students’ motivation sources and shows the high impact that work of professors has on students’ motivation. Common goal of most professors is to help students acquiring knowledge and competencies that are relevant for their further life. From the beginning of Universities’ history, lectures are usually chosen to reach this goal but it is seen in recent years that they are in many cases not the optimal choice. In the last years, many efforts were made to increase students knowledge gain. From learning and motivation psychology research, many details are known how humans remember and transfer knowledge. These research results are used to create new lecture formats to activate students. Research based learning, project based lab courses, problem based learning, feedback systems, flipped classroom, blended learning and gamification in lectures are only some examples for new formats. Common goal of all these new types of learning formats is to increasing students’ motivation and to enhance learning success. In this paper, evaluations using a questionnaire with open questions were done among first year students, bachelor students before graduation and alumni, about their sources of motivation and demotivation. Interesting curricula and lectures with application related topics and possibilities for own work are the main sources of motivation. Enthusiastic professors with high competences and good lecture didactics also contribute to students’ motivation. On the other side, demotivated professors with boring lectures play a much higher role for demotivating students. Therefore, it is necessary to integrate aspects of student motivation into curriculum and lecture design and professors should become aware that they are important role-models for motivating or demotivating students. KW - Computational modeling KW - Electrical engineering KW - Information technology KW - Psychology KW - Social networking (online) KW - Task analysis KW - Urban areas Y1 - 2018 U6 - https://doi.org/10.1109/FIE.2018.8658436 SP - 1 EP - 5 PB - IEEE ER - TY - CHAP A1 - Goetz, Rebecca A1 - Rauch, Johannes A1 - Brückl, Oliver ED - Schulz, Detlef T1 - Techno-economic analysis of reactive power sources T2 - NEIS 2021, Conference on Sustainable Energy Supply and Energy Storage Systems: Hamburg, 13.-14. September 2021 N2 - This paper presents different options to provide reactive power in electricity grid systems. Since conventional power plants are being phased out and the reactive power demand tends to increase, alternative technologies are needed to cover it. reactive power sources are being defined and specified in this submission. A technical evaluation and an economic analysis of selected reactive power sources are carried out, based on interviews with manufacturers and operators. As well a multifactorial techno-economic comparison of the evaluated reactive power sources is presented. The technical analysis addresses reactive power control-ranges, stochastic parameters, lifespans, electrical losses and dynamics of re-active power sources. It states that power electronics allow faster setpoint changes than mechanical technologies can achieve, but at the same time this is associated with the highest electrical losses of the reactive power sources considered here. Considering the economic analysis, relative investment costs per reactive power of conventional compensation systems turn out to be the most cost-efficient. With regard to the multifactorial techno-economic comparison, it is im-portant not only to standardize on reactive power that can be provided, but also to include the additional system-relevant properties of technologies in the evaluation as well as the costs in operation. Y1 - 2021 UR - https://ieeexplore.ieee.org/document/9698281/ SN - 978-3-8007-5651-3 SP - 286 EP - 291 PB - VDE-Verlag ER - TY - CHAP A1 - Klitsman, Maksym A1 - Brückl, Oliver A1 - Eller, Johannes ED - Schulz, Detlef T1 - Analysis and simulation of the population driving behaviour and charging processes at different charging station types with electric vehicles T2 - NEIS 2021, Conference on Sustainable Energy Supply and Energy Storage Systems: 13-14. September 2021, Hamburg N2 - Electric vehicles are one of the important components of the energy transition, which is necessary for the CO2 emission reduction. In order to estimate the influence of electromobility on electric grids at present day and in the future, the generation of realistic charge profiles is necessary. The main objective of this study is the development of an algorithm, which generates realistic charge time series of electric vehicles. The very huge and detailed input surveys enable to define different population groups, representing specific driving behaviour. These groups are then composed and scaled up, according to the statistical population structure of a chosen town or city in Germany, and show typical driving behaviour of all inhabitants. The charge profiles are calculated for several charge station types, based on daily electric vehicle user mobility, day type and household type. In addition, charge process occurrence is evaluated through a model, involving charge infrastructure presence, attractiveness of corresponding charge station type and charge process necessity. Y1 - 2021 SN - 978-3-8007-5651-3 SP - 254 EP - 260 PB - VDE-Verlag ER - TY - GEN A1 - Sterner, Michael T1 - Wie wird Deutschland klimaneutral? Neue Lösungen für erneuerbare Energieerzeugung T2 - Jahreskonferenz der Stiftung Nagelschneider zur Erforschung, München, 19.11.2021 KW - Erneuerbare Energien KW - Klimaneutralität KW - Energiewende KW - Klimaschutz Y1 - 2021 CY - München ER - TY - GEN A1 - Sterner, Michael T1 - Power-to-Gas technologies in the energy sector and their role in the fight against climate change T2 - Hungarian Power-to-Gas REKK Forum, Budapest Corvinus University, 12.02.2020 KW - Erneuerbare Energien KW - Klimaneutralität KW - Energiewende KW - Sektorenkopplung KW - Power-to-Gas Y1 - 2020 ER - TY - GEN A1 - Sterner, Michael A1 - Heberl, Michael T1 - The ORBIT-Project: Biological methanation in a trickle-bed reactor - key results and next steps T2 - 5th Nuremberg Workshop on Methanation and 2nd Generation, Nürnberg Friedrich-Alexander-Universität, 28.05.2021 KW - biologische Methanisierung KW - Archaeen KW - Power-to-Gas KW - Erneuerbare Energien KW - Rieselbett Bioreaktor Y1 - 2021 ER - TY - JOUR A1 - Gegenfurtner, Andreas A1 - Boucheix, Jean-Michel A1 - Gruber, Hans A1 - Hauser, Florian A1 - Lehtinen, Erno A1 - Lowe, Richard K. T1 - The gaze relational index as a measure of visual expertise JF - Journal of Expertise N2 - Eye tracking is a powerful technique that helps reveal how people process visual information. This paper discusses a novel metric for indicating expertise in visual information processing. Named the Gaze Relational Index (GRI), this metric is defined as the ratio of mean fixation duration to fixation count. Data from two eye-tracking studies of professional vision and visual expertise in using 3D dynamic medical visualizations are presented as cases to illustrate the suitability and additional benefits of the GRI. Calculated values of the GRI were higher for novices than for experts, and higher in non-representative, semi-familiar / unfamiliar task conditions than in domain-representative familiar tasks. These differences in GRI suggest that, compared to novices, experts engaged in more knowledge-driven, top-down processing that was characterized by quick, exploratory visual search. We discuss future research aiming to replicate the GRI in professional domains with complex visual stimuli and to identify the moderating role of cognitive ability on GRI estimates. KW - eye tracking KW - fixations KW - information processing KW - professional vision KW - visual expertise Y1 - 2020 UR - https://www.journalofexpertise.org/articles/volume3_issue1/JoE_3_1_Gegenfurtner.pdf SN - 2573-2773 VL - 3 IS - March SP - 32 EP - 40 PB - Michigan State University ER - TY - JOUR A1 - Sorokin, Vladislav V. A1 - Stepanov, Gennady V. A1 - Shamonin (Chamonine), Mikhail A1 - Monkman, Gareth J. A1 - Kramarenko, Elena Yu T1 - Magnetorheological behavior of magnetoactive elastomers filled with bimodal iron and magnetite particles JF - Smart materials and structures N2 - Magnetoactive elastomers (MAE) based on soft silicone matrices, filled with various proportions of large diameter ( approximately 50 mu m) iron and small diameter ( approximately 0.5 mu m) magnetite particles are synthesized. Their rheological behavior in homogeneous magnetic fields up to 600 mT is studied in detail. The addition of small magnetite particles facilitates fabrication of uniformly distributed magnetic elastomer composites by preventing aggregation and sedimentation of large particles during curing. It is shown that using the proposed bimodal filler particles it is possible to tailor various magnetorheological (MR) properties which can be useful for different target applications. In particular, either absolute or relative magnetorheological effects can be tuned. The value of the damping factor as well as the range of deformation amplitudes for the linear viscoelastic regime can be chosen. The interdependencies between different MR properties of bimodal MAEs are considered. The results are discussed in the model framework of particle network formation under the simultaneous influence of external magnetic fields and mechanical deformation. KW - damping factor KW - DAMPING PROPERTIES KW - FIELD KW - HYDROGELS KW - MAGNETOELASTIC BEHAVIOR KW - Magnetorheological effect KW - magnetorheological elastomer KW - mechanical hysteresis KW - Payne effect Y1 - 2017 U6 - https://doi.org/10.1088/1361-665X/26/3/035019 VL - 26 IS - 3 PB - IOP Publishing ER - TY - JOUR A1 - Kalita, Viktor M. A1 - Snarskii, Andrei A. A1 - Zorinets, Denis A1 - Shamonin (Chamonine), Mikhail T1 - Single-particle mechanism of magnetostriction in magnetoactive elastomers JF - Physical Review E N2 - Magnetoactive elastomers (MAEs) are composite materials comprised of micrometer-sized ferromagnetic particles in a nonmagnetic elastomermatrix. Asingle-particle mechanism ofmagnetostriction in MAEs, assuming the rotation of a soft magnetic, mechanically rigid particle with uniaxial magnetic anisotropy in magnetic fields is identified and considered theoretically within the framework of an alternative model. In this mechanism, the total magnetic anisotropy energy of the filling particles in the matrix is the sum over single particles. Matrix displacements in the vicinity of the particle and the resulting direction of the magnetization vector are calculated. The effect of matrix deformation is pronounced well if the magnetic anisotropy coefficient K is much larger than the shear modulus mu of the elastic matrix. The feasibility of the proposed magnetostriction mechanism in soft magnetoactive elastomers and gels is elucidated. The magnetic-field-induced internal stresses in the matrix lead to effects of magnetodeformation and may increase the elastic moduli of these composite materials. KW - BEHAVIOR KW - Deformation KW - DEPENDENCE KW - FERROGELS KW - HOMOGENEOUS MAGNETIC-FIELD KW - magnetodeformation KW - MICROSTRUCTURE KW - SENSITIVE ELASTOMERS Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevE.93.062503 VL - 93 IS - 6 PB - American Physical Society ER - TY - JOUR A1 - Burdin, Dmitrii A. A1 - Ekonomov, Nikolai A. A1 - Chashin, Dmitri V. A1 - Fetisov, Leonid Y. A1 - Fetisov, Yuri K. A1 - Shamonin (Chamonine), Mikhail T1 - Temperature Dependence of the Resonant Magnetoelectric Effect in Layered Heterostructures JF - Materials N2 - The dependence of the resonant direct magnetoelectric effect on temperature is studied experimentally in planar composite structures. Samples of rectangular shapes with dimensions of 5 mm x 20 mm employed ferromagnetic layers of either an amorphous (metallic glass) alloy or nickel with a thickness of 20-200 m and piezoelectric layers of single crystalline langatate material or lead zirconate titanate piezoelectric ceramics with a thickness of 500 m. The temperature of the samples was varied in a range between 120 and 390 K by blowing a gaseous nitrogen stream around them. It is shown that the effective characteristics of the magnetoelectric effectsuch as the mechanical resonance frequency f(r), the quality factor Q and the magnitude of the magnetoelectric coefficient (E) at the resonance frequencyare contingent on temperature. The interrelations between the temperature changes of the characteristics of the magnetoelectric effect and the temperature variations of the following material parametersYoung's modulus Y, the acoustic quality factor of individual layers, the dielectric constant epsilon, the piezoelectric modulus d of the piezoelectric layer as well as the piezomagnetic coefficients ((n)) of the ferromagnetic layerare established. The effect of temperature on the characteristics of the nonlinear magnetoelectric effect is observed for the first time. The results can be useful for designing magnetoelectric heterostructures with specified temperature characteristics, in particular, for the development of thermally stabilized magnetoelectric devices. KW - acoustic quality factor KW - composite structure KW - linear KW - magnetoelectric effect KW - magnetoelectric heterostructure KW - magnetostriction KW - nonlinear KW - piezoelectric KW - temperature dependence Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-32185 N1 - corresponding author: Mikhail Shamonin VL - 10 IS - 10 PB - MDPI ER - TY - JOUR A1 - Monkman, Gareth J. A1 - Sindersberger, Dirk A1 - Diermeier, Andreas A1 - Prem, Nina T1 - The magnetoactive electret JF - smart materials and structures N2 - A magnet which adheres to every surface, not only those of ferromagnetic materials, has hitherto been the domain of science fiction. Now for the first time such a novel device exists. The fusion of a permanently magnetized magnetoactive polymer containing hard magnetic particles and an electret enhanced with ferroelectric particles has resulted in the development of a new smart device-the magnetoactive electret. Magnetoactive electrets can be made to exhibit the usual magnetic properties of permanent magnetism together with the electrostatic properties of electrets. This results in simultaneous magnetoadhesion and electroadhesion forces from the same elastomeric element. The biasing field, needed to avoid discontinuities concerned with transition through the zero point in operating curves, is normally provided by means of either a magnetic or an electric field. This novel technology provides both bias options in a single device. KW - 6D printing KW - electret KW - electroadhesion KW - FLUIDS KW - MAGNETIC-FIELD KW - magnetoactive electret KW - magnetoactive polymer KW - magnetoadhesion KW - Magnetorheological elastomers KW - RHEOLOGY Y1 - 2017 U6 - https://doi.org/10.1088/1361-665X/aa738f VL - 26 IS - 7 PB - IOP Publishing ER - TY - JOUR A1 - Kinoshita, Keisuke A1 - Delcroix, Marc A1 - Gannot, Sharon A1 - Habets, Emanuel A. P. A1 - Haeb-Umbach, Reinhold A1 - Kellermann, Walter A1 - Leutnant, Volker A1 - Maas, Roland A1 - Nakatani, Tomohiro A1 - Raj, Bhiksha A1 - Sehr, Armin A1 - Yoshioka, Takuya T1 - A summary of the REVERB challenge: state-of-the-art and remaining challenges in reverberant speech processing research JF - Eurasip journal on advances in signal processing N2 - In recent years, substantial progress has been made in the field of reverberant speech signal processing, including both single- and multichannel dereverberation techniques and automatic speech recognition (ASR) techniques that are robust to reverberation. In this paper, we describe the REVERB challenge, which is an evaluation campaign that was designed to evaluate such speech enhancement (SE) and ASR techniques to reveal the state-of-the-art techniques and obtain new insights regarding potential future research directions. Even though most existing benchmark tasks and challenges for distant speech processing focus on the noise robustness issue and sometimes only on a single- channel scenario, a particular novelty of the REVERB challenge is that it is carefully designed to test robustness against reverberation, based on both real, single- channel, and multichannel recordings. This challenge attracted 27 papers, which represent 25 systems specifically designed for SE purposes and 49 systems specifically designed for ASR purposes. This paper describes the problems dealt within the challenge, provides an overview of the submitted systems, and scrutinizes them to clarify what current processing strategies appear effective in reverberant speech processing. KW - Automatic speech recognition KW - Dereverberation KW - Evaluation campaign KW - QUALITY KW - REVERB challenge KW - Reverberation Y1 - 2016 U6 - https://doi.org/10.1186/s13634-016-0306-6 VL - 2016 PB - Springer Nature ER - TY - JOUR A1 - Belyaeva, Inna A. A1 - Kramarenko, Elena Yu A1 - Shamonin (Chamonine), Mikhail T1 - Magnetodielectric effect in magnetoactive elastomers: Transient response and hysteresis JF - POLYMER N2 - Magnetodielectric properties of magnetoactive elastomers comprising micrometer-sized iron particles dispersed in compliant elastomer matrices are experimentally studied in stepwise time-varying dc magnetic fields. It is found that imposition of magnetic field significantly increases both the effective lossless permittivity of these composite materials as well as their effective conductivity. These magnetodielectric effects are more pronounced for larger concentrations of soft-magnetic filler particles and softer elastomer matrices. The largest observed relative change of the effective dielectric constant in the maximum magnetic field of 0.57 T is of the order of 1000%. The largest observed absolute change of the loss tangent is approximately 0.8. The transient response of the magnetodielectric effect to a step magnetic-field excitation can be rather complex. It changes from a simple monotonic growth with time for small magnetic-field steps (<0.1 T) to a non-monotonic behavior with a significant rapidly appearing overshoot for large magnetic-field steps (>0.3 T). The settling time to the magnetic-field step excitation can reach roughly 1000 s and it depends on the applied magnetic field and sample composition. There is also significant hysteresis of the magnetodielectric effect on the externally applied magnetic field. These findings are attributed to the rearrangement of ferromagnetic filler particles in external magnetic fields. The results will be useful for understanding and predicting the transient behavior of magnetoactive elastomers in applications where the control magnetic field is time dependent. (C) 2017 Elsevier Ltd. All rights reserved. KW - BEHAVIOR KW - composites KW - DIELECTRIC-PROPERTIES KW - hysteresis KW - MAGNETIC-FIELD KW - magnetoactive elastomer KW - magnetodielectric effect KW - Magnetorhelogical elastomer KW - MELT STATE KW - MICROSTRUCTURE KW - POLYMER DEGRADATION KW - PROGRESS KW - Smart material KW - THERMOOXIDATIVE DEGRADATION KW - TIME-RESOLVED RHEOLOGY KW - Transient response Y1 - 2017 U6 - https://doi.org/10.1016/j.polymer.2017.08.056 VL - 127 SP - 119 EP - 128 PB - ELSEVIER ER - TY - CHAP A1 - De, Sangita A1 - Mottok, Jürgen A1 - Niklas, Michael A1 - Brada, Premek ED - Trinitis, Carsten ED - Pionteck, Thilo T1 - Semantic Synergy Exploration in Interface Description Models of Heterogeneous Vehicle Frameworks: Towards Automotive Meta Interface Description Model T2 - ARCS 2019: 32nd GI/ITG International Conference on Architecture of Computing Systems May 20 - 21, 2019, Technical University of Denmark, Copenhagen, Denmark Workshop, Proceedings N2 - This The vehicle is evolving to a complex network of heterogeneous subsystems of ECUs, sensors and actuators, each with different computational requirements. These sub-systems are connected via bus systems following different communication paradigms like e.g. signal based or service-oriented communications. This has led to the heterogeneous syntax of describing interfaces even though the semantics of the interfaces are similar. The wide variety of Interface Description Languages (IDLs) in automotive industry hinders partly with the efficient collaboration between different suppliers and the OEMs in the automotive industry. Given this wide variety of automotive IDLs, what could be more beneficial, from a software engineering point of view, is a generic automotive domain specific IDL that can satisfy all the fundamental requirements of the heterogeneous subsystems. This paper describes an approach to compare and correlate IDLs based on semantic similarities of the languages, considering the two aspects: application description and underlying message frameworks used in the different domains of given automotive subsystems. With the exploration of semantic synergies between the IDLs, various domain specific and domain-agnostic frameworks can be compared and correlated. The results can be generalized and abstracted to define a generic Meta IDL which could support use cases like e.g. domain-agnostic functional models and migration of software components between different kinds of automotive subsystems. Y1 - 2019 UR - https://ieeexplore.ieee.org/document/8836199 SN - 978-3-8007-4957-7 SP - 63 EP - 70 PB - VDE VERLAG CY - Berlin ER - TY - JOUR A1 - Bodnaruk, Andrii V. A1 - Brunhuber, Alexander A1 - Kalita, Viktor M. A1 - Kulyk, Mykola M. A1 - Snarskii, Andrei A. A1 - Lozenko, Albert F. A1 - Ryabchenko, Sergey M. A1 - Shamonin (Chamonine), Mikhail T1 - Temperature-dependent magnetic properties of a magnetoactive elastomer: Immobilization of the soft-magnetic filler JF - Journal of Applied Physics N2 - The magnetic properties of a magnetoactive elastomer (MAE) filled with mu m-sized soft-magnetic iron particles have been experimentally studied in the temperature range between 150 K and 310 K. By changing the temperature, the elastic modulus of the elastomer matrix was modified, and it was possible to obtain magnetization curves for an invariable arrangement of particles in the sample and in the case when the particles were able to change their position within the MAE under the influence of magnetic forces. At low (less than 220 K) temperatures, when the matrix becomes rigid, the magnetization of the MAE does not show a hysteresis behavior, and it is characterized by a negative value of the Rayleigh constant. At room temperature, when the polymer matrix is compliant, a magnetic hysteresis exists where the dependence of the differential magnetic susceptibility on the magnetic field exhibits local maxima. The appearance of these maxima is explained by the elastic resistance of the matrix to the displacement of particles under the action of magnetic forces. KW - BEHAVIOR KW - composites KW - FIELD KW - GELS KW - hysteresis KW - Magnetorheological elastomers KW - MICROSTRUCTURE KW - PERMEABILITY KW - RAYLEIGH LAW KW - STRAIN Y1 - 2018 U6 - https://doi.org/10.1063/1.5023891 VL - 123 IS - 11 PB - AIP Publishing ER - TY - JOUR A1 - Jordaan, Joshua A1 - Punzet, Stefan A1 - Melnikov, Anton A1 - Sanches, Alexandre A1 - Oberst, Sebastian A1 - Marburg, Steffen A1 - Powell, David A. T1 - Measuring monopole and dipole polarizability of acoustic meta-atoms JF - Applied physics letters N2 - We present a method to extract monopole and dipole polarizability from experimental measurements of two-dimensional acoustic meta-atoms. In contrast to extraction from numerical results, this enables all second-order effects and uncertainties in material properties to be accounted for. We apply the technique to 3D-printed labyrinthine meta-atoms of a variety of geometries. We show that the polarizability of structures with a shorter acoustic path length agrees well with numerical results. However, those with longer path lengths suffer strong additional damping, which we attribute to the strong viscous and thermal losses in narrow channels. KW - METASURFACE KW - SOUND Y1 - 2018 U6 - https://doi.org/10.1063/1.5052661 VL - 113 IS - 22 PB - AIP Publishing ER - TY - JOUR A1 - Knörzer, S. A1 - Hiller, Karl-Anton A1 - Brandt, M. A1 - Niklas, Andreas A1 - Putzger, Jürgen A1 - Monkman, Gareth J. A1 - Danilov, Sergey N. A1 - Ganichev, Sergey D. A1 - Schulz, Irene A1 - Schmalz, Gottfried T1 - Detection of pulsed blood flow through a molar pulp chamber and surrounding tissue in vitro JF - Journal of Clinical Oral Investigations N2 - OBJECTIVES Due to severe limitations of dental pulp sensitivity tests, the direct recording of pulsed blood flow, using photoplethysmography (PPG), has been proposed. In vivo evaluation is methodologically difficult and in vitro models have hitherto been adversely influenced by shortcomings in emulating the in vivo situation. Consequently, the aim of this study was to test an improved data acquisition system and to use this configuration for recording pulsed blood in a new model. MATERIALS AND METHODS We introduced a PPG signal detection system by recording signals under different blood flow conditions at two wavelengths (625 and 940 nm). Pulsed blood flow signals were measured using an in vitro model, containing a molar with a glass pulp and a resin socket, which closely resembled in vivo conditions with regard to volumetric blood flow, pulp anatomy, and surrounding tissue. RESULTS The detection system showed improved signal strength without stronger blanketing of noise. On the tooth surface, it was possible to detect signals emanating from pulsed blood flow from the glass pulp and from surrounding tissue at 625 nm. At 940 nm, pulp derived signals were recorded, without interference signals from surrounding tissue. CONCLUSION The PPG-based method has the potential to detect pulsed blood flow in small volumes in the pulp and (at 625 nm) also in adjacent tissues. CLINICAL RELEVANCE The results show the need for clear differentiation of the spatial origins of blood flow signals of any vitality test method to be applied to teeth. KW - Dental Pulp KW - Dental Pulp Cavity KW - Dental Pulp Test KW - Laser-Doppler Flowmetry KW - Molar Y1 - 2019 U6 - https://doi.org/10.1007/s00784-018-2530-y VL - 23 IS - 3 SP - 1121 EP - 1132 PB - Springer Nature ER - TY - JOUR A1 - Snarskii, Andrei A. A1 - Kalita, Viktor M. A1 - Shamonin (Chamonine), Mikhail T1 - Renormalization of the critical exponent for the shear modulus of magnetoactive elastomers JF - Scientific Reports N2 - It is shown that the critical exponent for the effective shear modulus of a composite medium where a compliant polymer matrix is filled with ferromagnetic particles may significantly depend on the external magnetic field. The physical consequence of this dependence is the critical behavior of the relative magnetorheological effect. Y1 - 2018 U6 - https://doi.org/10.1038/s41598-018-22333-6 N1 - Corresponding author: Mikhail Shamonin VL - 8 SP - 1 EP - 8 PB - Nature ER - TY - JOUR A1 - Prem, Nina A1 - Chavez Vega, Jhohan Harvey A1 - Böhm, Valter A1 - Sindersberger, Dirk A1 - Monkman, Gareth J. A1 - Zimmermann, Klaus T1 - Properties of Polydimethylsiloxane and Magnetoactive Polymers with Electroconductive Particles JF - Macromolecular Chemistry and Physics N2 - Magnetoactive polymers are intelligent materials whose mechanical and electrical characteristics are reversibly influenced by external magnetic stimuli. They consist of a highly elastic polymer matrix in which magnetically soft and/or hard particles are distributed by means of special fabrication processes. In addition to ferromagnetic particles such as carbonyl iron powder, electrically conductive particles may also be embedded into the polymer matrix. After characterizing a range of compounds, this work focuses on a comparison of the electrical properties and the suitability of various materials for applications, with particular emphasis on integration into 3D and 6D printing processes. 6D printing is based on the selective positioning of particles in a 3D polymer matrix with a further three degrees of freedom for a graduated dispersion of the particles at certain points and in desired directions. The aim is therefore to ensure that the polymers containing electroconductive tracks have the best possible electrical properties, that is, low resistivity but are still capable of being printed. A comparison between the traditionally used compounds containing graphite and carbon black is made for the first time. This latter is found to be greatly superior both in terms of electrical conductivity and applicability to 3D printing and 6D printing. KW - 3D printing KW - 6D printing KW - carbon black KW - composites KW - electroconductive particles KW - graphite KW - magnetoactive polymers KW - polydimethylsiloxane KW - STRAIN, *MRU Y1 - 2018 U6 - https://doi.org/10.1002/macp.201800222 VL - 219 IS - 18 PB - Wiley ER - TY - JOUR A1 - Steinkirchner, Alfons A1 - Fuhrmann, Thomas A1 - Niemetz, Michael T1 - Channel Coded Processor for Enhanced Safety JF - International Journal of Future Computer and Communication (IJFCC) N2 - Several concepts are known for improving processor safety, all of them having their pros and cons. Some are very resource intensive, others have limited capabilities regarding the provided error safety. In this paper we use research on channel coding of noisy communication channels known from communication theory as an analogy to random bit errors in processors. We incorporate this knowledge into processor design to suggest a new error correction concept by using channel coding in processors. The new concept of a Channel Coded Processor could provide effective implementation of redundancy by the channel coding that enables error correction. The concept could also create a complete chain of redundancy in all areas and components of the processor ranging from the code compiler through the processing hardware to the output of the information. KW - Channel coded processor concept KW - communication theory KW - safety KW - soft error Y1 - 2017 U6 - https://doi.org/10.18178/ijfcc.2017.6.2.489 SN - 2010-3751 VL - 6 IS - 2 SP - 58 EP - 62 PB - International Association of Computer Science and Information CY - Singapore ER - TY - JOUR A1 - Zimmermann, Klaus A1 - Böhm, Valter A1 - Becker T.I., A1 - Chavez Vega, Jhohan Harvey A1 - Kaufhold, Tobias A1 - Monkman, Gareth J. A1 - Sindersberger, Dirk A1 - Diermeier, Andreas A1 - Prem, Nina T1 - Mechanical Characterization of the Field-Dependent Properties of Magnetoactive Polymers and Integrated Electrets for their Application in Soft Robotics JF - International Scientific Journal "Problems of Mechanics" Y1 - 2017 SN - 1512-0740 VL - 69 IS - 4 ER - TY - JOUR A1 - Dechant, Eduard A1 - Fedulov, Feodor A1 - Chashin, Dmitri V. A1 - Fetisov, Leonid Y. A1 - Fetisov, Yuri K. A1 - Shamonin (Chamonine), Mikhail T1 - Low-frequency, broadband vibration energy harvester using coupled oscillators and frequency up-conversion by mechanical stoppers JF - Smart Materials and Structures N2 - The frequencies of ambient vibrations are often low (below 30 Hz). A broadband (3 dB bandwidth is larger than 10 Hz at an acceleration amplitude of 9.81 m s(-2)) vibration based energy harvester is proposed for transducing mechanical energy at such low frequencies into electrical energy. The mechanical setup converts low frequency mechanical vibrations into high frequency resonance oscillations of the transducer. This conversion is done by mechanical impacts on two mechanical stoppers. The originality of the presented design is that both low-frequency and high-frequency oscillators are permanently mechanically coupled. In the equivalent mechanical circuit, this coupling is achieved by connecting the ends of the stiff spring to both seismic masses, whereas one seismic mass (collison member) is also attached to the soft spring used as the constitutive element of a low-frequency oscillator. Further, both mechanical oscillators are not realized as conventional cantilever beams. In particular, the high frequency oscillator with the natural frequency of 340 Hz is a disc-shaped diaphragm with attached piezoelectric elements and a seismic mass. It is shown that it is possible to convert mechanical vibrations with acceleration amplitude of 9.81 m s(-2) in the region between approximately 7 and 25 Hz into electrical power larger than 0.1 mW with the maximum value of 0.8 mW. A simplified mathematical model based on piecewise linear coupled oscillators shows good agreement with experimental results. The ways to enhance the performance of the harvester and improve agreement with experiments are discussed. KW - broadband KW - efficiency KW - frequency up-conversion KW - low frequency KW - mechanical stoppers KW - Modeling KW - OUTPUT KW - Piezoelectric transducer KW - vibration energy harvesting Y1 - 2017 U6 - https://doi.org/10.1088/1361-665X/aa6e92 VL - 26 IS - 6 PB - IOP Publishing ER - TY - JOUR A1 - Sorokin, Vladislav V. A1 - Belyaeva, Inna A. A1 - Shamonin (Chamonine), Mikhail A1 - Kramarenko, Elena Yu T1 - Magnetorheological response of highly filled magnetoactive elastomers from perspective of mechanical energy density: Fractal aggregates above the nanometer scale? JF - Physical Review E N2 - The dynamic shear modulus of magnetoactive elastomers containing 70 and 80 mass % of carbonyl iron microparticles is measured as a function of strain amplitude via dynamic torsion oscillations in various magnetic fields. The results are presented in terms of the mechanical energy density and considered in the framework of the conventional Kraus model. The form exponent of the Kraus model is further related to a physical model of Huber et al. [Huber et al., J. Phys.: Condens. Matter 8, 409 (1996)] that uses a realistic representation for the cluster network possessing fractal structure. Two mechanical loading regimes are identified. At small strain amplitudes the exponent beta of the Kraus model changes in an externally applied magnetic field due to rearrangement of ferromagnetic-filler particles, while at large strain amplitudes, the exponent beta seems to be independent of the magnetic field. The critical mechanical energy characterizing the transition between these two regimes grows with the increasing magnetic field. Similarities between agglomeration and deagglomeration of magnetic filler under simultaneously applied magnetic field and mechanical shear and the concept of jamming transition are discussed. It is proposed that the magnetic field should be considered as an additional parameter to the jamming phase diagram of rubbers filled with magnetic particles. KW - BEHAVIOR KW - composites KW - hysteresis KW - MAGNETIC-FIELD KW - MODEL KW - RHEOLOGY KW - RUBBER KW - SENSITIVE ELASTOMERS KW - VISCOELASTIC PROPERTIES Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevE.95.062501 VL - 95 IS - 6 PB - Amer Physical Soc ER - TY - JOUR A1 - Diermeier, Andreas A1 - Sindersberger, Dirk A1 - Krenkel, Lars A1 - Rosell, X. C. A1 - Monkman, Gareth J. T1 - Controllable Magnetoactive Polymer Conduit JF - The Open Mechanical Engineering Journal N2 - Objective: Magneto-active Polymers (MAP) are smart materials whose mechanical characteristics, such as elastic and shear moduli, may be controllable by means of an externally applied magnetic field. Methods: Various additives may be used to influence the characteristics of the polymer matrix whilst a suspension of soft and/or hard magnetic particles determine the magnetic properties of the composite. Both pre-cure and post-cure magnetization is possible. Results: A range of control strategies have been investigated for evaluation of the system using fluids of differing kinematic viscosity. Conclusion: Depending on the degree of magnetic field homogeneity, magneto-deformation and magnetostriction contribute to MAP actuation. This paper presents a novel application in the form of a peristaltic MAP tube system, applicable to flow control and pumping of hemorheological fluids in blood circulatory systems for biomedical research purposes. Y1 - 2018 UR - https://www.benthamopen.com/ABSTRACT/TOMEJ-12-192 N1 - Corresponding authro: Gareth J. Monkman VL - 12 IS - 1 SP - 192 EP - 200 PB - Bentham ER - TY - JOUR A1 - Fuhrmann, Thomas A1 - Mottok, Jürgen T1 - Ethical, intercultural and professional impulses integrated into a transmission systems lecture JF - 2017 IEEE Global Engineering Education Conference (EDUCON), 25-28 April 2017, Athens, Greece N2 - In the sixth semester of the bachelor study course “Electrical Engineering and Information Technology”, a lecture “Transmission Systems” is given. It explains basic principles, circuits and systems of electrical and optical transmission systems. Short intellectual impulses, which address professional, intercultural and ethical issues of engineers' working life are integrated into this regular lecture. In each lecture unit, an impulse with one specific topic is given approximately in the middle of the lecture hour. An evaluation was done at the end of the semester, which shows that most of the students remember the discussed topics and state high interest due to high importance for their professional life. Due to these encouraging results, this concept will be developed further. KW - Engineering Education KW - Ethics Education KW - Electrical Engineering Y1 - 2017 U6 - https://doi.org/10.1109/EDUCON.2017.7942829 SP - 92 EP - 95 PB - IEEE ER - TY - JOUR A1 - Dechant, Eduard A1 - Fedulov, Feodor A1 - Fetisov, Leonid Y. A1 - Shamonin (Chamonine), Mikhail T1 - Bandwidth Widening of Piezoelectric Cantilever Beam Arrays by Mass-Tip Tuning for Low-Frequency Vibration Energy Harvesting JF - Applied Science N2 - Wireless sensor networks usually rely on internal permanent or rechargeable batteries as a power supply, causing high maintenance efforts. An alternative solution is to supply the entire system by harvesting the ambient energy, for example, by transducing ambient vibrations into electric energy by virtue of the piezoelectric effect. The purpose of this paper is to present a simple engineering approach for the bandwidth optimization of vibration energy harvesting systems comprising multiple piezoelectric cantilevers (PECs). The frequency tuning of a particular cantilever is achieved by changing the tip mass. It is shown that the bandwidth enhancement by mass tuning is limited and requires several PECs with close resonance frequencies. At a fixed frequency detuning between subsequent PECs, the achievable bandwidth shows a saturation behavior as a function of the number of cantilevers used. Since the resonance frequency of each PEC is different, the output voltages at a particular excitation frequency have different amplitudes and phases. A simple power-transfer circuit where several PECs with an individual full wave bridge rectifier are connected in parallel allows one to extract the electrical power close to the theoretical maximum excluding the diode losses. The experiments performed on two- and three-PEC arrays show reasonable agreement with simulations and demonstrate that this power-transfer circuit additionally influences the frequency dependence of the harvested electrical power. KW - array KW - BAND-PASS FILTERS KW - bandwidth KW - BIMORPH KW - Optimization KW - OUTPUT KW - PERFORMANCE KW - piezoelectric cantilever KW - POWER KW - vibration energy harvesting Y1 - 2017 U6 - https://doi.org/10.3390/app7121324 N1 - Corresponding Author: Mikhail Shamonin VL - 7 IS - 12 PB - MDPI ER -