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 - da Silva Mota, Fabio Antonio A1 - Hinckel, Jose Nivaldo A1 - Rocco, Evandro Marconi A1 - Schlingloff, Hanfried T1 - Trajectory Optimization of Launch Vehicles Using Object-oriented Programming JF - Journal of aerospace technology and management N2 - The aim of this study is to model launch vehicles with focus on 3-DOF trajectory optimization using a modular approach. Despite the large number of operational launch vehicles, they usually consist of basic components and subsystems. In other words, a launch vehicle is an assembly of stages, which in turn is divided into propellant system and engine, and the engine is an assembly of basic components such as pumps, turbines, combustion chamber, and nozzle. To allow future extension and reuse of the codes, a modular structure using object-oriented programming is used. Two formulations of state equations of the trajectory and two optimization methods are described. The launch vehicle performance will be measured by payload mass for a given mission. The simulations of the VLS-1, Ariane 5 and VLS-Alfa were performed and showed good agreement with the literature. KW - Launch vehicle KW - Object-oriented programming KW - Optimization KW - Trajectory Y1 - 2018 U6 - https://doi.org/10.5028/jatm.v10.948 VL - 10 PB - Institute of Aeronautics and Space ER - TY - JOUR A1 - Kurzweil, Peter A1 - Shamonin (Chamonine), Mikhail T1 - State-of-Charge Monitoring by Impedance Spectroscopy during Long-Term Self-Discharge of Supercapacitors and Lithium-Ion Batteries JF - Batteries N2 - Frequency-dependent capacitance C(ω) is a rapid and reliable method for the determination of the state-of-charge (SoC) of electrochemical storage devices. The state-of-the-art of SoC monitoring using impedance spectroscopy is reviewed, and complemented by original 1.5-year long-term electrical impedance measurements of several commercially available supercapacitors. It is found that the kinetics of the self-discharge of supercapacitors comprises at least two characteristic time constants in the range of days and months. The curvature of the Nyquist curve at frequencies above 10 Hz (charge transfer resistance) depends on the available electric charge as well, but it is of little use for applications. Lithium-ion batteries demonstrate a linear correlation between voltage and capacitance as long as overcharge and deep discharge are avoided. KW - aging KW - capacitance KW - self-discharge KW - state-of-charge monitoring KW - supercapacitor Y1 - 2018 U6 - https://doi.org/10.3390/batteries4030035 VL - 4 IS - 3 SP - 1 EP - 13 PB - MPDI ER - TY - JOUR A1 - Alvarez Moret, Judit A1 - Obermeier, Tina A1 - Pohl, Fabian A1 - Löschel, Rainer A1 - Kölbl, Oliver A1 - Dobler, Barbara T1 - Second cancer risk after radiation therapy of ependymoma using the flattening filter free irradiation mode of a linear accelerator JF - Journal of Applied Clinical Medical Physics N2 - Pediatric patients suffering from ependymoma are usually treated with cranial or craniospinal three-dimensional (3D) conformal radiotherapy (3DCRT). Intensity-modulated techniques spare dose to the surrounding tissue, but the risk for second malignancies may be increased due to the increase in low-dose volume. The aim of this study is to investigate if the flattening filter free (FFF) mode allows reducing the risk for second malignancies compared to the mode with flattening filter (FF) for intensity-modulated techniques and to 3DCRT. A reduction of the risk would be advantageous for treating pediatric ependymoma. 3DCRT was compared to intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) with and without flattening filter. Dose-volume histograms (DVHs) were compared to evaluate the plan quality and used to calculate the excess absolute risk (EAR) to develop second cancer in the brain. Dose verification was performed with a two-dimensional (2D) ionization chamber array and the out-of-field dose was measured with an ionization chamber to determine the EAR in peripheral organs. Delivery times were measured. Both VMAT and IMRT achieved similar plan quality in terms of dose sparing in the OAR and higher PTV coverage as compared to 3DCRT. Peripheral dose in low-dose region, which is proportional to the EAR in organs located in this region, for example, gonads, bladder, or bowel, could be significantly reduced using FFF. The lowest peripheral EAR and lowest delivery times were hereby achieved with VMATFFF . The EAR calculated based on DVH in the brain could not be reduced using FFF mode. VMATFFF improved the target coverage and homogeneity and kept the dose in the OAR similar compared to 3DCRT. In addition, delivery times were significantly reduced using VMATFFF . Therefore, for radiotherapy of ependymoma patients, VMATFFF may be considered advantageous for the combination of Elekta Synergy linac and Oncentra External Beam planning system used in this study. KW - Adolescent KW - Child KW - Child, Preschool KW - Ependymoma/radiotherapy KW - Humans KW - Infant KW - Neoplasms, Radiation-Induced KW - Neoplasms, Second Primary KW - Particle Accelerators KW - Radiotherapy Dosage KW - Radiotherapy Planning, Computer-Assisted KW - Radiotherapy, Intensity-Modulated KW - Retrospective Studies Y1 - 2018 U6 - https://doi.org/10.1002/acm2.12438 VL - 19 IS - 5 SP - 632 EP - 639 PB - Wiley ER - TY - JOUR A1 - Schmitz, Paul A1 - Neumann, Christoph Cornelius A1 - Neumann, Carsten A1 - Nerlich, Michael A1 - Dendorfer, Sebastian T1 - Biomechanical analysis of iliac crest loading following cortico-cancellous bone harvesting JF - Journal of Orthopaedic Surgery and Research N2 - Background Iliac crest bone harvesting is a frequently performed surgical procedure widely used to treat bone defects. The objective of this study is to assess the biomechanical quantities related to risk for pelvic fracture after harvesting an autologous bone graft at the anterior iliac crest. Methods Finite element models with a simulated harvest site (sized 15 × 20 mm, 15 × 35 mm, 30 × 20 mm and 30 × 35 mm) in the iliac wing are created. The relevant loading case is when the ipsilateral leg is lifted off the ground. Musculoskeletal analysis is utilized to compute the muscle and joint forces involved in this motion. These forces are used as boundary conditions for the finite element analyses. Bone tissue stress is analyzed. Results Critical stress peaks are located between the anterior superior iliac spine (ASIS) and the anterior edge of the harvest site. Irrespective of the graft size, the iliac wing does not show any significant stress peaks with the harvest site being 20 to 25 mm posterior to the ASIS. The harvest area itself inhibits the distribution of the forces applied on the ASIS to extend to the posterior iliac wing. This leads to a lack of stress posterior to the harvest site. A balanced stress distribution with no stress peaks appears when the bone graft is taken below the iliac crest. Conclusion A harvest site located at least 20 to 25 mm posterior to the ASIS should be preferred to minimize the risk of iliac fatigue fracture. KW - Bone harvesting KW - Autologous bone graft KW - Iliac crest KW - Fatigue fracture KW - Pelvis KW - ASIS KW - FEA KW - Biomechanical investigation KW - Beckenkammknochen KW - Knochenentnahme KW - Spongiosa KW - Biomechanische Analyse Y1 - 2018 U6 - https://doi.org/10.1186/s13018-018-0822-1 VL - 13 IS - 108 SP - 1 EP - 8 PB - Springer Nature ER - TY - JOUR A1 - Weber, Karsten T1 - Computers as omnipotent instruments of power BT - Hopes, fears and actual change in administration, politics, and society from the 1960s to 1980s JF - The ORBIT Journal - An Online Journal for Responsible Research and Innovation in ICT N2 - With examples concerning the development and dissemination of computer technology in the Soviet Union, the U.S., and other Western countries it shall be demonstrated that computer development on the one hand and social change as well as changes in policy making and administration on the other hand are mingled with each other without a clear direction of causation being discernible.It also shall be shown that perceived social and political threats imposed by early computer technology sometimes actually helped to stop or at least slow down social change. One conclusion that can be drawn from the case studies described for RRI is that the conscious steering of innovations fails because of diffuse and uncoordinated resistance from very different stakeholders. The case studies also suggest that the effectiveness of RRI might be rather limited. Y1 - 2018 U6 - https://doi.org/10.29297/orbit.v2i1.97 VL - 2 IS - 1 SP - 1 EP - 19 PB - Elsevier ER - TY - JOUR A1 - Keller, Helena A1 - Greim, Markus A1 - Kusterle, Wolfgang T1 - 27th Conference and Workshop on Rheology of Building Materials, Ostbayerische Technische Hochschule (OTH) Regensburg, Germany, March 7 – 8, 2018 BT - Conference report JF - Applied Rheology Y1 - 2018 U6 - https://doi.org/10.1515/arh-2018-0005 VL - 28 IS - 2 SP - 56 EP - 58 PB - De Gruyter ER - TY - CHAP A1 - Altenbuchner, Amelie A1 - Haug, Sonja A1 - Kretschmer, Rainer A1 - Weber, Karsten T1 - How to Measure Physical Motion and the Impact of Individualized Feedback in the Field of Rehabilitation of Geriatric Trauma Patients T2 - Health Informatics Meets eHealth N2 - Background: This preparatory study accelerates an implementation of individualized monitoring and feedback of physical motion using conventional motion trackers in the rehabilitation process of geriatric trauma patients. Regaining mobility is accompanied with improved quality of life in persons of very advanced age recovering from fragility fractures. Objectives: Quantitative survey of regaining physical mobility provides recommendations for action on how to use motion trackers effectively in a clinical geriatric setting. Methods: Method mix of quantitative and qualitative interdisciplinary and mutual complementary research approaches (sociology, health research, philosophy/ethics, medical informatics, nursing science, gerontology and physical therapy). While validating motion tracker use in geriatric traumatology preliminary data are used to develop a target group oriented motion feedback. In addition measurement accuracy of a questionnaire about quality of life of multimorbid geriatric patients (FLQM) is tested. Conclusion: Implementing a new technology in a complex clinical setting needs to be based on a strong theoretical background but will not succeed without careful field testing. KW - Health monitoring KW - motion tracker KW - quality of life KW - geriatric assessment Y1 - 2018 U6 - https://doi.org/10.3233/978-1-61499-858-7-226 SP - 226 EP - 232 ER - TY - JOUR A1 - Weber, Karsten A1 - Haug, Sonja T1 - Ist automatisiertes Fahren nachhaltig? BT - Entwicklungstendenzen und Forschungsüberlegungen angesichts geringer Akzeptanz JF - TATuP - Zeitschrift für Technikfolgenabschätzung in Theorie und Praxis N2 - Automatisiertes Fahren stößt derzeit noch auf große Skepsis. Eine disruptive Strategie bei der Einführung (voll-)automatisierten Fahrens könnte daher auf fehlende Akzeptanz treffen. Um dem zu entgehen, laufen evolutionäre Strategien darauf hinaus, durch die Entwicklung adaptiver Fahrassistenzsysteme Vertrautheit, Vertrauen und damit Akzeptanz bei den prospektiven NutzerInnen zu schaffen. Erste Ergebnisse einer Pilotstudie lassen jedoch Zweifel an der Nachhaltigkeit dieser Strategie aufkommen. KW - driver assistance systems KW - automated driving KW - acceptance KW - sustainability Y1 - 2018 U6 - https://doi.org/10.14512/tatup.27.2.16 VL - 27 IS - 2 SP - 16 EP - 22 PB - Karlsruhe Institute of Technology (KIT) ER - TY - JOUR A1 - Goldhacker, Markus A1 - Tomé, Ana Maria A1 - Greenlee, Mark W. A1 - Lang, Elmar Wolfgang T1 - Frequency-Resolved Dynamic Functional Connectivity Reveals Scale-Stable Features of Connectivity-States JF - Frontiers in Human Neuroscience N2 - Investigating temporal variability of functional connectivity is an emerging field in connectomics. Entering dynamic functional connectivity by applying sliding window techniques on resting-state fMRI (rs-fMRI) time courses emerged from this topic. We introduce frequency-resolved dynamic functional connectivity (frdFC) by means of multivariate empirical mode decomposition (MEMD) followed up by filter-bank investigations. In general, we find that MEMD is capable of generating time courses to perform frdFC and we discover that the structure of connectivity-states is robust over frequency scales and even becomes more evident with decreasing frequency. This scale-stability varies with the number of extracted clusters when applying k-means. We find a scale-stability drop-off from k = 4 to k = 5 extracted connectivity-states, which is corroborated by null-models, simulations, theoretical considerations, filter-banks, and scale-adjusted windows. Our filter-bank studies show that filter design is more delicate in the rs-fMRI than in the simulated case. Besides offering a baseline for further frdFC research, we suggest and demonstrate the use of scale-stability as a possible quality criterion for connectivity-state and model selection. We present first evidence showing that connectivity-states are both a multivariate, and a multiscale phenomenon. A data repository of our frequency-resolved time-series is provided. Y1 - 2018 U6 - https://doi.org/10.3389/fnhum.2018.00253 SN - 1662-5161 VL - 12 SP - 1 EP - 16 PB - Frontiers Research Foundation CY - Lausanne ER -