TY - JOUR A1 - Froese, Vincent A1 - Jain, Brijnesh A1 - Niedermeier, Rolf A1 - Renken, Malte T1 - Comparing temporal graphs using dynamic time warping JF - Social Network Analysis and Mining N2 - Within many real-world networks, the links between pairs of nodes change over time. Thus, there has been a recent boom in studying temporal graphs. Recognizing patterns in temporal graphs requires a proximity measure to compare different temporal graphs. To this end, we propose to study dynamic time warping on temporal graphs. We define the dynamic tem- poral graph warping (dtgw) distance to determine the dissimilarity of two temporal graphs. Our novel measure is flexible and can be applied in various application domains. We show that computing the dtgw-distance is a challenging (in general) NP-hard optimization problem and identify some polynomial-time solvable special cases. Moreover, we develop a quadratic programming formulation and an efficient heuristic. In experiments on real-world data, we show that the heuristic performs very well and that our dtgw-distance performs favorably in de-anonymizing networks compared to other approaches. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-38493 VL - 10 SP - 1 EP - 16 PB - Springer Nature ER - TY - JOUR A1 - Monkman, Gareth J. A1 - Striegl, Birgit A1 - Prem, Nina A1 - Sindersberger, Dirk T1 - Electrical Properties of Magnetoactive Boron‐Organo‐Silicon Oxide Polymers JF - Macromolecular Chemistry and Physics N2 - The electrical properties of rheopectic magnetoactive composites comprising boron-organo-silicon oxide dielectric matrices containing carbonyl iron microparticles are presented for the first time. The increase in interfacial magnetocapacitance is seen to greatly exceed that experienced when using conventional elastomeric matrices such as polydimethylsiloxane. In addition to the increase in capacitance, a simultaneous and sharp decrease in the parallel electrical resistance over several orders of magnitude is also observed. The effects are time dependent but repeatable. Potential applications include magnetically controlled frequency dependent devices, magnetic sensor systems, weighting elements for neural networks, etc. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-26488 N1 - Corresponding author: Gareth J. Monkman VL - 221 IS - 4 SP - 1 EP - 8 PB - Wiley ER - TY - JOUR A1 - Prem, Nina A1 - Sindersberger, Dirk A1 - Monkman, Gareth J. T1 - Infrared spectral analysis of low concentration magnetoactive polymers JF - Journal of Applied Polymer Science N2 - This work concerns an area of magnetoactive polymer (MAP) research seldom considered. Traditionally only MAP with high concentrations of magnetic filler (typically between 10 and 90 wt%) have been investigated. This article deals with a hitherto neglected aspect of research, namely MAP containing lower magnetic filler concentrations (1 to 3 wt%). This article utilizes a range of spectroscopic analysis methods (Raman and FTIR) and their applicability to MAP characterization at wavelengths ranging from 2.5 to 25 mu m. Particular attention is paid to low carbonyl iron particle (CIP) concentrations in MAP for which the emergence of capillary doublets at a critical 2 wt% concentration is revealed. This results in measurable magnetic field-dependent changes in IR absorption at a wavelength of 4.255 mu m together with a detectable CO2 susceptibility. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48366. KW - ELASTOMERS KW - magnetism and magnetic properties KW - sensors and actuators KW - spectroscopy Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-25913 SN - 1097-4628 N1 - Corresponding author: Nina Prem VL - 137 IS - 7 SP - 1 EP - 7 PB - Wiley ER - TY - JOUR A1 - Becker, Tatiana I. A1 - Raikher, Yuriy L. A1 - Stolbov, Oleg V. A1 - Böhm, Valter A1 - Zimmermann, Klaus T1 - Magnetoactive elastomers for magnetically tunable vibrating sensor systems JF - Physical Sciences Reviews N2 - Magnetoactive elastomers (MAEs) are a special type of smart materials consisting of an elastic matrix with embedded microsized particles that are made of ferromagnetic materials with high or low coercivity. Due to their composition, such elastomers possess unique magnetic field-dependent material properties. The present paper compiles the results of investigations on MAEs towards an approach of their potential application as vibrating sensor elements with adaptable sensitivity. Starting with the model-based and experimental studies of the free vibrational behavior displayed by cantilevers made of MAEs, it is shown that the first bending eigenfrequency of the cantilevers depends strongly on the strength of an applied uniform magnetic field. The investigations of the forced vibration response of MAE beams subjected to in-plane kinematic excitation confirm the possibility of active magnetic control of the amplitude-frequency characteristics. With change of the uniform field strength, the MAE beam reveals different steady-state responses for the same excitation, and the resonance may occur at various ranges of the excitation frequency. Nonlinear dependencies of the amplification ratio on the excitation frequency are obtained for different magnitudes of the applied field. Furthermore, it is shown that the steady-state vibrations of MAE beams can be detected based on the magnetic field distortion. The field difference, which is measured simultaneously on the sides of a vibrating MAE beam, provides a signal with the same frequency as the excitation and an amplitude proportional to the amplitude of resulting vibrations. The presented prototype of the MAE-based vibrating unit with the field-controlled “configuration” can be implemented for realization of acceleration sensor systems with adaptable sensitivity. The ongoing research on MAEs is oriented to the use of other geometrical forms along with beams, e.g. two-dimensional structures such as membranes. KW - adaptable sensor unit KW - amplification ratio KW - bending vibration KW - eigenfrequency KW - Magnetic field control KW - magnetoactive elastomer Y1 - 2020 U6 - https://doi.org/10.1515/psr-2019-0125 SN - 2365-659X VL - 7 IS - 10 SP - 1 EP - 28 PB - de Gruyter ER - TY - JOUR A1 - Wiesent, Lisa A1 - Schultheiß, Ulrich A1 - Lulla, Philipp A1 - Nonn, Aida A1 - Noster, Ulf T1 - Mechanical properties of small structures built by selective laser melting 316 L stainless steel – a phenomenological approach to improve component design JF - Materials Science & Engineering Technology JF - Materialwissenschaft und Werkstofftechnik N2 - Experimental investigations are conducted to quantify the influence of specimen thickness and orientation on the mechanical properties of selective laser melted stainless steel 316 L. The results indicate that the mechanical strength and ductility increase with increasing specimen thickness until a saturation value is reached from a specimen thickness of about 2 mm. Specimen orientation dependency is pronounced for thin specimens (<1.5 mm), whereas only small deviations in strength are observed for thicker specimens with orientations of 30°, 45° and 90° to build direction. The mechanical properties of the specimen orientation of 0° to build direction shows great deviation to the other orientations and the smallest overall strength. A reliable design of selective laser melted components should account for specimen thickness and orientation, e. g. by a correction factor. Furthermore, it is recommended to avoid loads vertical (90°) and parallel (0°) to build direction to guarantee higher ductility and strength. T2 - Mechanische Eigenschaften von kleinen Strukturen aus selektiv lasergeschmolzenem 316 L Edelstahl – ein phänomenologischer Ansatz zur Verbesserung des Bauteildesigns Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-14718 N1 - Corresponding author: Lisa Wiesent VL - 51 IS - 12 SP - 1615 EP - 1629 PB - Wiley ER - TY - JOUR A1 - Prem, Nina A1 - Sindersberger, Dirk A1 - Striegl, Birgit A1 - Böhm, Valter A1 - Monkman, Gareth J. T1 - Shape memory effects using magnetoactive Boron-organo-silicon oxide polymers JF - Macromolecular Chemistry and Physics N2 - Thermomechanical shape memory materials have certain disadvantages when it comes to 3D volumetric reproduction intended for rapid prototyping or robotic prehension. The need to constantly supply energy to counteract elastic retraction forces in order to maintain the required geometry, together with the inability to achieve conformal stability at elevated temperatures, limits the application of thermal shape memory polymers. Form removal also presents problems as most viscoelastic materials do not ensure demolding stability. This work demonstrates how magnetoactive boron−organo−silicon oxide polymers under the influence of an applied magnetic field can be used to achieve energy free sustainable volumetric shape memory effects over extended periods. The rheopectic properties of boron−organo−silicon oxide materials sustain form removal without mold distortion. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-23205 N1 - Corresponding Author: Gareth J. Monkman VL - 221 IS - 15 SP - 1 EP - 8 PB - Wiley ER - TY - JOUR A1 - Engelhardt, Lucas A1 - Melzner, Maximilian A1 - Havelkova, Linda A1 - Fiala, Pavel A1 - Christen, Patrik A1 - Dendorfer, Sebastian A1 - Simon, Ulrich T1 - A new musculoskeletal AnyBodyTM detailed hand model JF - Computer Methods in Biomechanics and Biomedical Engineering N2 - Musculoskeletal research questions regarding the prevention or rehabilitation of the hand can be addressed using inverse dynamics simulations when experiments are not possible. To date, no complete human hand model implemented in a holistic human body model has been fully developed. The aim of this work was to develop, implement, and validate a fully detailed hand model using the AnyBody Modelling System (AMS) (AnyBody, Aalborg, Denmark). To achieve this, a consistent multiple cadaver dataset, including all extrinsic and intrinsic muscles, served as a basis. Various obstacle methods were implemented to obtain with the correct alignment of the muscle paths together with the full range of motion of the fingers. These included tori, cylinders, and spherical ellipsoids. The origin points of the lumbrical muscles within the tendon of the flexor digitorum profundus added a unique feature to the model. Furthermore, the possibility of an entire patient-specific scaling based on the hand length and width were implemented in the model. For model validation, experimental datasets from the literature were used, which included the comparison of numerically calculated moment arms of the wrist, thumb, and index finger muscles. In general, the results displayed good comparability of the model and experimental data. However, the extrinsic muscles showed higher accordance than the intrinsic ones. Nevertheless, the results showed, that the proposed developed inverse dynamics hand model offers opportunities in a broad field of applications, where the muscles and joint forces of the forearm play a crucial role. KW - Musculoskeletal KW - hand KW - AnyBody KW - inverse dynamics KW - moment arm Y1 - 2020 U6 - https://doi.org/10.1080/10255842.2020.1851367 VL - 24 IS - 7 SP - 777 EP - 787 PB - Taylor & Francis ER - TY - JOUR A1 - Schecklmann, Martin A1 - Schmausser, Maximilian A1 - Klinger, Felix A1 - Kreuzer, Peter M. A1 - Krenkel, Lars A1 - Langguth, Berthold T1 - Resting motor threshold and magnetic field output of the figure-of-8 and the double-cone coil JF - scientific reports N2 - The use of the double-cone (DC) coil in transcranial magnetic stimulation (TMS) is promoted with the notion that the DC coil enables stimulation of deeper brain areas in contrast to conventional figure-of-8 (Fo8) coils. However, systematic comparisons of these two coil types with respect to the spatial distribution of the magnetic field output and also to the induced activity in superficial and deeper brain areas are limited. Resting motor thresholds of the left and right first dorsal interosseous (FDI) and tibialis anterior (TA) were determined with the DC and the Fo8 coil in 17 healthy subjects. Coils were orientated over the corresponding motor area in an angle of 45 degrees for the hand area with the handle pointing in posterior direction and in medio-lateral direction for the leg area. Physical measurements were done with an automatic gantry table using a Gaussmeter. Resting motor threshold was higher for the leg area in contrast to the hand area and for the Fo8 in contrast to the DC coil. Muscle by coil interaction was also significant providing higher differences between leg and hand area for the Fo8 (about 27%) in contrast to the DC coil (about 15%). Magnetic field strength was higher for the DC coil in contrast to the Fo8 coil. The DC coil produces a higher magnetic field with higher depth of penetration than the figure of eight coil. KW - ANTERIOR CINGULATE CORTEX KW - CONNECTIVITY KW - Depression KW - FRONTAL-CORTEX KW - PREDICTOR KW - RTMS KW - STIMULATION KW - TMS Y1 - 2020 U6 - https://doi.org/10.1038/s41598-020-58034-2 VL - 10 IS - 1 PB - Nature ER - TY - JOUR A1 - Görtler, Michael T1 - Zeit als (knappe) Ressource sozialpädagogischen Handelns: Eine empirische Untersuchung zur Bedeutung von Zeit in der sozialpädagogische Praxis JF - Diskurs Kindheits- und Jugendforschung KW - CC_BY_4.0 Y1 - 2020 U6 - https://doi.org/10.3224/diskurs.v15i1.09 SN - 1862-5002 SN - 2193-9713 VL - 15 IS - 1 SP - 109 EP - 113 PB - Verlag Barbara Budrich ER - TY - JOUR A1 - Linner, Thomas A1 - Seelinger, Anja A1 - Vogt Lydia, A1 - Schäpers Barbara, A1 - Steinböck, Martina A1 - Krewer, Carmen A1 - Bock, Thomas T1 - REACH: Solutions for Technology-Based Prevention and Empowerment for Older People and their Caregivers JF - Journal of Population Ageing: Special Issue on responsive engagement of older persons promoting activity and customized healthcare N2 - REACH stands for “Responsive Engagement of the Elderly Promoting Activity and Customized Healthcare”. Sustained physical activity matters greatly to the health and well-being of older people and significantly improves their chance of maintaining independent living. It can make a difference across the whole care continuum as well as in almost every setting. Therefore, REACH solutions focus on the systematic, target-oriented increase of physical activity of older people, and tackle the whole prevention spectrum (primary, secondary, and tertiary). It seeks to empower older people and their formal and informal caregivers, and works towards viable solutions for both the formal and in-formal care sector. Technology-based personalization of prevention, activation, and care services provided in various living and care settings is at the center of the developed solutions. Ideally toolkit approach would allow for the tailoring of solutions that create value for end-users, care providers and health care payers alike through the combination, integration and adaptation/re-design elements towards the different contexts of different countries, different payment and reimbursement structures. This Special Issue sheds light on such solutions, their conception, their development, and their testing. Y1 - 2020 U6 - https://doi.org/10.1007/s12062-020-09268-5 VL - 13 IS - 1 SP - 131 EP - 137 PB - Springer Nature ER -