@article{9767, abstract = {{The paper presents the results of numerical and experimental investigation of cylindrical piezoelectric actuator used for achieving independent three degrees of freedom oscillations of the contact point. The design of actuator based on a hollow piezoelectric cylinder mounted on a metal rod. The piezoceramic cylinder has a radial polarization and special configuration of the electrodes that cover inner and outer surface of the cylinder. The main advantage of actuator's design is that solid metallic rod operates as a part of inner electrode of the cylinder and a stator of actuator. The geometry of piezoelectric actuator was adopted to reach resonance of oscillations for the first longitudinal mode and the third flexural mode at same frequency. The actuator is designed to move positioned object through contact point which is located on the top of the rod. The optimal topology of electrodes was found to achieve longitudinal and flexural oscillations of the actuator in two perpendicular planes. Three degrees of freedom of the positioning object can be achieved and control of the system can be implemented by applying different excitation schemes and regimes. The numerical simulation and experimental study of piezoelectric actuator was performed. Impedance of actuator was analyzed under different excitation regimes. The results of numerical modeling and experimental study were compared. Recommendations for the further development of this type of actuator are given.}}, author = {{Lucinskis, Raimundas and Mazeika, Dalius and Hemsel, Tobias and Bansevicius, Ramutis}}, journal = {{AIP Conference Proceedings}}, keywords = {{dielectric polarisation, piezoceramics, piezoelectric actuators}}, number = {{1}}, pages = {{693--696}}, publisher = {{AIP}}, title = {{{Multi-DOF cylindrical piezoelectric actuator with radial polarization}}}, doi = {{10.1063/1.3703277}}, volume = {{1433}}, year = {{2011}}, } @article{9769, abstract = {{In this study, we report some improvements in a hydrothermal method for lead-free piezoelectric powders and the performance of the sintered (K$_{0.48}$Na$_{0.52}$)NbO$_{3}$ ceramics. To increase the obtained powder weight per source solution volume, the hydrothermal reaction conditions were modified. This improvement is important for mass production; however, it resulted in a larger particle size dispersion. Therefore, we examined to introduced the ball milling process that is useful for dense (K$_{0.48}$Na$_{0.52}$)NbO$_{3}$ ceramics. When a large amount of powder was obtained, it took a long time to eliminate the residual alkaline ions in the hydrothermal powders by a washing process. Therefore, a neutralization was conducted in the powder washing process. Using this powder, a solid solution of (K,Na)NbO$_{3}$ceramics was synthesized. The relative density was successfully increased. Concerning the electrical properties, the relative permittivity was improved, and the piezoelectric constant d$_{33}$ was also increased from 114 to 130 pC/N.}}, author = {{Maeda, Takafumi and Hemsel, Tobias and Morita, Takeshi}}, journal = {{Japanese Journal of Applied Physics}}, pages = {{07HC01}}, publisher = {{The Japan Society of Applied Physics}}, title = {{{Improved Process for Hydrothermal Lead-Free Piezoelectric Powders and Performances of Sintered (K0.48Na0.52)NbO3 Ceramics}}}, volume = {{50}}, year = {{2011}}, } @inproceedings{9770, abstract = {{One cannot image today's life without mechatronic systems, which have to be developed in a joint effort by teams of mechanical engineers, electrical engineers, control engineers and software engineers. Often these systems are applied in safety critical environments like in cars or aircrafts. This requires systems that function correctly and do not cause hazardous situations. However, random errors due to wear or external influences cannot be completely excluded. Consequently, we have to perform a hazard analysis for the system. Further, the union of four disciplines in one system requires the development and analysis of the system as a whole. We present a component-based hazard analysis that considers the entire mechatronic system including hardware, i.e. mechanical and electrical components, and software components. Our approach considers the physical properties of different types of flow in mechatronic systems. We have identified reusable patterns for the failure behavior which can be generated automatically. This reduces the effort for the developer. As cycles, e.g. control cycles, are an internal part of every mechatronic system our approach is able to handle cycles. The presented approach has been applied to a real-life case study.}}, author = {{Priesterjahn, Claudia and Sondermann-Wölke, Christoph and Tichy, Mathias and Hölscher, Christian}}, booktitle = {{Proc. of the 2nd IEEE International Workshop MoBE-RTES at the 14th IEEE International Symposium on Object/Component/Service-oriented Real-time Distributed Computing (ISORC)}}, publisher = {{IEEE Computer Society}}, title = {{{Component-based Hazard Analysis for Mechatronic Systems}}}, year = {{2011}}, } @article{9772, abstract = {{A profound description of friction in wheel--rail contact plays an essential role for optimization of traction control strategies, as input quantity for railway simulations in general and for the estimation of wear and rolling contact fatigue. A multitude of wheel--rail contact models exists, however, traction--creepage curves obtained from measurements show quantitative and qualitative deviations. There are several phenomena which influence the traction--creepage characteristics: Mechanisms resulting from surface roughness, frictional heating or the presence of interfacial fluids can have a dominating influence on friction. In this paper, a new wheel--rail contact model, accounting for these influential parameters, will be presented. The presented model accounts for the interaction of an interfacial fluid model for combined boundary and mixed lubrication of rough surfaces with a wheel--rail contact model that additionally accounts for frictional heating. A quantitative comparison with measurements found in the literature is not conducted, since the exact conditions of the measurements are mostly unknown and parameters can easily be adjusted to fit the measurements. Emphasis is placed on the qualitative behavior of the model with respect to the measurements and good agreement is found. The dependence of the maximum traction coefficient on rolling velocity, surface roughness and normal load is studied under dry and water lubricated conditions.}}, author = {{Tomberger, Christoph and Dietmaier, Peter and Sextro, Walter and Six, Klaus}}, issn = {{0043-1648}}, journal = {{Wear}}, keywords = {{Wheel--rail contact, Rolling contact, Friction, Interfacial fluid, Lubrication, Surface roughness, Contact temperature}}, pages = {{2 -- 12}}, title = {{{Friction in wheel--rail contact: A model comprising interfacial fluids, surface roughness and temperature}}}, doi = {{10.1016/j.wear.2010.10.025}}, volume = {{271}}, year = {{2011}}, } @article{9877, author = {{Isobe, Gaku and Bornmann, Peter and Hemsel, Tobias and Morita, Takeshi}}, journal = {{Proceedings of Symposium on Ultrasonic Electronics}}, pages = {{19--20}}, publisher = {{Trans Tech Publ}}, title = {{{High temperature tolerant transducer for Ultrasonic Assisted Hydrothermal Method}}}, volume = {{32}}, year = {{2011}}, } @article{16000, author = {{Marten, Thorsten and Niewel, J. and Tröster, Thomas}}, issn = {{1867-2493}}, journal = {{HTM Journal of Heat Treatment and Materials}}, pages = {{309--315}}, title = {{{Untersuchung alternativer Erwärmungsverfahren für den Presshärteprozess}}}, doi = {{10.3139/105.110119}}, year = {{2011}}, } @inproceedings{22029, abstract = {{In this work the influence of the orientation and the toolpath generation of manufactured parts based on the mechanical data are analyzed. Tensile Specimen are generated with the given parameters as well as with changing parameters of the native software based upon the CAD data. The parts then are built up with the “Fortus 400mc” from Stratasys. First tensile tests show different strength and strain characteristics that depend on the given structure and as a result of the build direction. The influence of the parameters was analyzed with a statistic test method by using the software Design Expert.}}, author = {{Bagsik, A. and Schöppner, Volker}}, booktitle = {{ANTEC}}, pages = {{1294--1298}}, title = {{{Mechanical Properties of Fused Deposition Modeling Parts Manufactured with ULTEM*9085}}}, doi = {{https://www.researchgate.net/profile/Volker_Schoeppner/publication/284341800_Mechanical_properties_of_fused_deposition_modeling_parts_manufactured_with_ULTEMzast9085/links/5c73971b458515831f6cd501/Mechanical-properties-of-fused-deposition-modeling-parts-manufactured-with-ULTEM-zast9085.pdf}}, year = {{2011}}, } @article{28046, author = {{Bloh, Bea and Drossel, Kerstin}}, journal = {{Empirische Pädagogik}}, number = {{2}}, pages = {{145--160}}, title = {{{Formen der Lehrerkooperation und ihre schulischen Bedingungen. Empirische Untersuchung zur kollegialen Zusammenarbeit und Schulleitungshandeln.}}}, volume = {{25}}, year = {{2011}}, } @article{28048, author = {{Gerick, Julia and Bloh, Bea}}, journal = {{Schulverwaltung NRW}}, pages = {{268--270}}, title = {{{Erweiterter Gestaltungspielraum für Schulen. Welche Veränderungen beschreiben Schulleiterinnen und Schulleiter in ihrem beruflichen Selbstverständnis?}}}, volume = {{10}}, year = {{2011}}, } @article{28042, author = {{Bloh, Bea and van Ophuysen, Stefanie}}, journal = {{Journal for Educational Research Online}}, number = {{1}}, pages = {{141--167}}, title = {{{Transformationale Führung in Schulen. Der Einsatz des "Multifactor Leadership Questionnaire" (MLQ 5 x Short)}}}, volume = {{3}}, year = {{2011}}, } @inbook{28043, author = {{Bloh, Bea and Gieske, Mario and Gerick, Julia}}, booktitle = {{Neue Steuerung - Alte Ungleichheiten?}}, editor = {{Dietrich, F. and Heinrich, M. and Thieme, N.}}, pages = {{101--112}}, title = {{{Schulleitungstypen in eigenverantwortlichen Schulen}}}, year = {{2011}}, } @article{28049, author = {{Bloh, Bea}}, journal = {{Lernende Schule}}, number = {{53}}, pages = {{18--21}}, title = {{{Für eine gesunde Schule sorgen: Lehrergesundheit als Aufgabe der Schulleitung – Entlastung als Qualitätsmerkmal.}}}, volume = {{14}}, year = {{2011}}, } @article{35342, author = {{Youssry, Mohamed and Coppola, Luigi and Nicotera, Isabella and Ar, Gönül and Schmidt, Claudia}}, issn = {{0021-9797}}, journal = {{Journal of Colloid and Interface Science}}, keywords = {{Colloid and Surface Chemistry, Surfaces, Coatings and Films, Biomaterials, Electronic, Optical and Magnetic Materials}}, number = {{2}}, pages = {{506--512}}, publisher = {{Elsevier BV}}, title = {{{Effect of shear on vesicle and lamellar phases of DDAB/lecithin ternary systems}}}, doi = {{10.1016/j.jcis.2011.03.053}}, volume = {{358}}, year = {{2011}}, } @article{35344, author = {{Bayer, Frank M. and Tang, Mingxue and Michels, Rolf and Schmidt, Claudia and Huber, Klaus}}, issn = {{0743-7463}}, journal = {{Langmuir}}, keywords = {{Electrochemistry, Spectroscopy, Surfaces and Interfaces, Condensed Matter Physics, General Materials Science}}, number = {{21}}, pages = {{12851--12858}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Molecular Recognition with 2,4-Diaminotriazine-Functionalized Colloids}}}, doi = {{10.1021/la202685e}}, volume = {{27}}, year = {{2011}}, } @article{5973, author = {{Åslund, Ingrid and Medronho, Bruno and Topgaard, Daniel and Söderman, Olle and Schmidt, Claudia}}, issn = {{1090-7807}}, journal = {{Journal of Magnetic Resonance}}, number = {{2}}, pages = {{291--299}}, publisher = {{Elsevier BV}}, title = {{{Homogeneous length scale of shear-induced multilamellar vesicles studied by diffusion NMR}}}, doi = {{10.1016/j.jmr.2011.01.024}}, volume = {{209}}, year = {{2011}}, } @article{35346, author = {{Medronho, Bruno and Brown, Jennifer and Miguel, Maria Graça and Schmidt, Claudia and Olsson, Ulf and Galvosas, Petrik}}, issn = {{1744-683X}}, journal = {{Soft Matter}}, keywords = {{Condensed Matter Physics, General Chemistry}}, number = {{10}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{Planar lamellae and onions: a spatially resolved rheo–NMR approach to the shear-induced structural transformations in a surfactant model system}}}, doi = {{10.1039/c0sm01323d}}, volume = {{7}}, year = {{2011}}, } @inproceedings{11889, abstract = {{In this paper we propose to jointly consider Segmental Dynamic Time Warping and distance clustering for the unsupervised learning of acoustic events. As a result, the computational complexity increases only linearly with the dababase size compared to a quadratic increase in a sequential setup, where all pairwise SDTW distances between segments are computed prior to clustering. Further, we discuss options for seed value selection for clustering and show that drawing seeds with a probability proportional to the distance from the already drawn seeds, known as K-means++ clustering, results in a significantly higher probability of finding representatives of each of the underlying classes, compared to the commonly used draws from a uniform distribution. Experiments are performed on an acoustic event classification and an isolated digit recognition task, where on the latter the final word accuracy approaches that of supervised training.}}, author = {{Schmalenstroeer, Joerg and Bartek, Markus and Haeb-Umbach, Reinhold}}, booktitle = {{Interspeech 2011}}, title = {{{Unsupervised learning of acoustic events using dynamic time warping and hierarchical K-means++ clustering}}}, year = {{2011}}, } @inproceedings{11896, abstract = {{In this paper we propose a procedure for estimating the geometric configuration of an arbitrary acoustic sensor placement. It determines the position and the orientation of microphone arrays in 2D while locating a source by direction-of-arrival (DoA) estimation. Neither artificial calibration signals nor unnatural user activity are required. The problem of scale indeterminacy inherent to DoA-only observations is solved by adding time difference of arrival (TDOA) measurements. The geometry calibration method is numerically stable and delivers precise results in moderately reverberated rooms. Simulation results are confirmed by laboratory experiments.}}, author = {{Schmalenstroeer, Joerg and Jacob, Florian and Haeb-Umbach, Reinhold and Hennecke, Marius and Fink, Gernot A.}}, booktitle = {{Interspeech 2011}}, title = {{{Unsupervised Geometry Calibration of Acoustic Sensor Networks Using Source Correspondences}}}, year = {{2011}}, } @inproceedings{9456, abstract = {{In this paper we present our experimental results about classifying audio data into broad acoustic categories. The reverberated sound samples from indoor recordings are grouped into four classes, namely speech, music, acoustic events and noise. We investigated a total of 188 acoustic features and achieved for the best configuration a classification accuracy better than 98\%. This was achieved by a 42-dimensional feature vector consisting of Mel-Frequency Cepstral Coefficients, an autocorrelation feature and so-called track features that measure the length of ''traces'' of high energy in the spectrogram. We also found a 4-feature configuration with a classification rate of about 90\% allowing for broad acoustic category classification with low computational effort.}}, author = {{Schmalenstroeer, Joerg and Bartek, Markus and Haeb-Umbach, Reinhold}}, booktitle = {{37. Deutsche Jahrestagung fuer Akustik (DAGA 2011)}}, title = {{{Investigations into Features for Robust Classification into Broad Acoustic Categories}}}, year = {{2011}}, } @inproceedings{24034, author = {{Lindemann, Christian-Friedrich and Pottebaum, Jens and Hofinger, Gesine and Künzer, Laura and Koch, Rainer}}, booktitle = {{Software Engineering 2011 - Workshopband (inkl. Doktorandensymposium), Fachtagung des GI-Fachbereichs Softwaretechnik, 21.-25.02.2011, Karlsruhe}}, editor = {{Reussner, Ralf H. and Pretschner, Alexander and J{\"a}hnichen, Stefan}}, isbn = {{978-3-88579-278-9}}, keywords = {{Ver{\}}, pages = {{193--204}}, publisher = {{GI}}, title = {{{Interdisziplinäre Anforderungsanalyse bei der Gestaltung von Systemen zur Erstellung eines gemeinsamen Lagebilds in großen Schadenslagen}}}, year = {{2011}}, }