@article{9571, abstract = {{Several positioning tasks demand translatory drive instead of rotary motion. To achieve drives that are capable, e.g., to drive the sunroof of a car or to lift a car's window, multiple miniaturized motors can be combined. But in this case many other questions arise: The electromechanical behavior of the individual motors differs slightly, the motor characteristics are strongly dependent on the driving parameters and the driven load, many applications need some extra power for special cases like overcoming higher forces periodically. Thus, the bundle of motors has to act well-organized and at last controlled to get an optimized drive that is not oversized and costly.}}, author = {{Mracek, Maik and Hemsel, Tobias and Sattel, Thomas and Vasiljev, Piotr and Wallaschek, Jörg}}, issn = {{1385-3449}}, journal = {{Journal of Electroceramics}}, keywords = {{Ultrasonic linear motor, High power, Control, Modeling, Characteristics}}, number = {{3-4}}, pages = {{153--158}}, publisher = {{Springer US}}, title = {{{Driving concepts for bundled ultrasonic linear motors}}}, doi = {{10.1007/s10832-007-9123-5}}, volume = {{20}}, year = {{2008}}, } @inproceedings{9573, abstract = {{Integrating dependability in self-optimizing systems is a challenging task. Self-optimizing systems incorporate on the one hand the opportunity to apply novel solutions to complex mechatronic systems, but on the other hand constitute a possible risk because of non-determined behavior. The dependability concept in this paper covers both aspects: Increasing safety with selfoptimization and minimizing the risk of self-optimization. This dependability concept is combined with the self-optimization process of the active guidance module which is currently under development at the Collaborative Research Center 614 at the University of Paderborn.}}, author = {{Sondermann-Wölke, Christoph and Geisler, Jens and Müler, Thomas and Trächtler, Ansgar and Böcker, Joachim}}, booktitle = {{ASME 2008 -- International Design Engineering Technical Conferences \& Computers and Information in Engineering Conference (IDETC/CIE)}}, title = {{{The active guidance module of a rail-bound vehicle as an application for the dependability oriented design in self-optimizing systems}}}, year = {{2008}}, } @article{9574, abstract = {{For devices having non-linear contact, load plays a fundamental role. Variations in the characteristics of the load cause change in eigenfrequency and amplitude of the vibration. In most technical applications, this unwanted behaviour is cancelled by the use of control algorithms. However, multiple applications, like bond quality monitoring or chemical and pressure sensors, have found that the load may be characterised by interpreting the change in characteristics of a resonant vibrating device used as a sensor. Surgical resection of tumours is a very difficult task. After localising the tumour by the use of imaging techniques, the resection demands the surgeon to decide where and what to resect based on visual and tactile differentiation of tumour and healthy tissue. Exactness of this process could be enhanced if we can provide the surgeon with a device capable of evaluating mechanical characteristics of the tissue much more accurately than the surgeon himself can do. As the mechanical characteristics of tumour and healthy tissue differ but slightly, the task is to design a system with high sensitivity. Therefore, we have developed a resonant actuator-sensor that allows the differentiation among distinct media that have similar mechanical characteristics to tumour and healthy tissue using a piezoelectric bimorph. The design is based on the detection and evaluation of frequency shift and amplitude variation of the fundamental and higher harmonics using one layer for the resonant excitation of vibration and the other one as the sensing element.}}, author = {{Stroop, Ralf and Uribe, David Oliva and Martinez, Melisa Orta and Brökelmann, Michael and Hemsel, Tobias and Wallaschek, Jörg}}, issn = {{1385-3449}}, journal = {{Journal of Electroceramics}}, keywords = {{Piezo ceramics, Bimorph, Tactile sensor, Tumour tissue}}, number = {{3-4}}, pages = {{237--241}}, publisher = {{Springer US}}, title = {{{Tactile tissue characterisation by piezoelectric systems}}}, doi = {{10.1007/s10832-007-9183-6}}, volume = {{20}}, year = {{2008}}, } @article{9575, abstract = {{Many ultrasonic processes are based on the mechanical contact of oscillating parts. Within ultrasonic machining (drilling, milling, grinding) micro impacts lead to abrasion at the processed workpiece and hopefully do not damage the tool. In ultrasonic motors ideally neither part gets worn. Thus the appropriate design of contact partners as well as their kinematics is a substantial task during the development of such devices. A first step to optimize contact mechanics is to understand their behavior and dependencies on parameter variations, such as vibration amplitude and pre-stress of the impacting parts. For a detailed understanding models validated with convincing experimental data from measurements are absolutely essential. This paper focuses on simple vibro-impact experiments which can be used as benchmark data for future models. The setup of the experiment and first experimental investigations are described in detail.}}, author = {{Twiefel, Jens and Potthast, Christian and Mracek, Maik and Hemsel, Tobias and Sattel, Thomas and Wallaschek, Jörg}}, issn = {{1385-3449}}, journal = {{Journal of Electroceramics}}, keywords = {{Contact measurements, Vibro-impact, Ultrasonic application}}, number = {{3-4}}, pages = {{209--214}}, publisher = {{Springer US}}, title = {{{Fundamental experiments as benchmark problems for modeling ultrasonic micro-impact processes}}}, doi = {{10.1007/s10832-007-9169-4}}, volume = {{20}}, year = {{2008}}, } @inproceedings{9576, abstract = {{In neurosurgery, delineation of tumor boundaries during resection of brain tumors is of substantial relevance. During operation distinction between tumor and healthy tissue rely on the abilities of the surgeon based on visual and tactile differentiation. In this paper a high sensitivity actuator-sensor system using a piezoelectric bimorph is presented. Frequency shift and transfer function of the bimorphpsilas voltages are detected and evaluated. Sensorpsilas sensitivity is evaluated using two frequency controls strategies: A phase-locked loop (PLL) and a self-oscillating circuit. Results of measurements conducted on gel-phantoms are presented and discussed.}}, author = {{Uribe, David Oliva and Stroop, Ralf and Hemsel, Tobias and Wallaschek, Jörg}}, booktitle = {{Frequency Control Symposium, 2008 IEEE International}}, issn = {{1075-6787}}, keywords = {{biomedical measurement, brain, cancer, neurophysiology, phantoms, phase locked loops, piezoelectric actuators, surgery, tactile sensors, transfer functions, tumours, PLL, biomedical tissue differentiation system, brain tumor resection, frequency control, frequency shift, gel-phantom, high sensitivity actuator-sensor system, neurosurgery, phase-locked loop, piezoelectric actuators, piezoelectric bimorph, self-oscillating circuit, sensor sensitivity, tactile differentiation, tactile sensor system, transfer function, tumor boundary, visual differentiation, Biomedical measurements, Circuits, Frequency control, Neoplasms, Neurosurgery, Phase locked loops, Piezoelectric actuators, Surges, Transfer functions, Voltage}}, pages = {{91--94}}, title = {{{Development of a biomedical tissue differentiation system using piezoelectric actuators}}}, doi = {{10.1109/FREQ.2008.4622963}}, year = {{2008}}, } @misc{9572, author = {{Rischmueller, Volker and Wallaschek, Jörg and Froehlich, Peter and Haussecker, Walter and Rieger, Vincent and Twiefel, Jens and Guenther, Dirk and Hemsel, Tobias}}, title = {{{Patent EP2156480: Piezoelektrische Antriebsvorrichtung / Piezoelectric Drive Unit}}}, year = {{2008}}, } @inproceedings{9560, author = {{Tonchev, Anton and Hirschberg, Wolfgang and Sextro, Walter and Major, Zoltan and Neges, Josef}}, booktitle = {{27. Internationales Mju-Symposium/Bremsen-Fachtagung}}, number = {{657}}, pages = {{29 -- 49}}, publisher = {{VDI Verlag GmbH}}, title = {{{Modellierung der Hysterese- und Adhäsionseffekte zwischen Bremsbelag und Bremsscheibe}}}, year = {{2007}}, } @inproceedings{9561, author = {{Tonchev, Anton and Hirschberg, Wolfgang and Sextro, Walter and Major, Zoltan and Neges, Josef}}, booktitle = {{27. Internationales Mju-Symposium/Bremsen-Fachtagung}}, number = {{657}}, pages = {{144--163}}, publisher = {{VDI Verlag GmbH}}, title = {{{Modelling of Hysteresis and Adhesion Effects between Brake Pad and Disc}}}, year = {{2007}}, } @inproceedings{9562, abstract = {{Penetration tests (Magness-Taylor, force/deformation, Kramer multiblade shear) applied directly over the peel of the fruit are the most acceptable methods for measuring firmness and turgidity of fruits and vegetables [1, 2]. To replace these destructive and mechanical penetration methods by non-destructive ultrasonic measurements implies a great advance in order to obtain fast studies about the state of the fruit at the time of harvest, during storage, and in the distribution points. Moreover, there are other advantages since this technique can be fast, non-destructive, fully automated, and performed on-line [1]. Within this context, the objective of this study was to examine the relationship between physico-mechanical characteristics (oil-gland break stress, thickness and dehydration) and ultrasonic characteristics in the ``Salustiana'' orange peel during the complete dehydration process of the orange at ambient conditions. After a description of the measurement system [3], the fruit selection procedure and the measurement protocol, we analyze the results of the change of physico-mechanical and ultrasonic properties in the orange peel and their change with storage time.}}, author = {{Camarena Gandia, Francisco and Hemsel, Tobias and Espinosa, Victor and Twiefel, Jens and Ardid, Miquel and Martinez-Mora, Joan and Gandia, Joan Babtiste}}, booktitle = {{Proceedings of 19th international congress on Acoustics, Madrid}}, title = {{{Non-destructive ultrasonic test of orange dehydration}}}, year = {{2007}}, } @inproceedings{9563, author = {{Genzo, Alexander and Sextro, Walter and Panning, Lars}}, booktitle = {{VDI-Berichte}}, pages = {{147--161}}, publisher = {{VDI Verlag GmbH}}, title = {{{Schwingungsverhalten elastischer Körper mit nichtlinearen Kopplungen in ausgedehnten Reibkontakten}}}, volume = {{2022}}, year = {{2007}}, } @article{9564, abstract = {{Surgical resection of brain tumours is a difficult task. To enhance surgery results, a tactile sensor is wanted that gives better resolution and sensitivity than the human tactile sense. The characteristics of resonant vibrating piezoelectric elements change with varying load. This allows for calculation of mechanical load parameters by measuring electrical quantities. Different setups of piezoelectric sensors have been used to investigate soft materials. Finally, a piezoelectric bimorph sensor gave good results for distinguishing tissue mimicking gel-phantoms with different gelatine concentrations. }}, author = {{Hemsel, Tobias and Stroop, Ralf and Oliva Uribe, David and Wallaschek, Jörg}}, issn = {{0022-460X}}, journal = {{Journal of Sound and Vibration}}, pages = {{441 -- 446}}, title = {{{Resonant vibrating sensors for tactile tissue differentiation}}}, doi = {{10.1016/j.jsv.2007.03.063}}, volume = {{308}}, year = {{2007}}, } @inproceedings{9565, author = {{Lierke, Ernst-Günter and Hemsel, Tobias}}, booktitle = {{Proceedings of 19th international congress on Acoustics, Madrid}}, title = {{{Perspectives of Tumour Therapy by Local Ultrasonic Hyperthermia and Thermal Ablation}}}, year = {{2007}}, } @article{9566, author = {{Shigematsu , Takashi and Morita, Takeshi and Hemsel, Tobias}}, journal = {{Proceedings of Symposium on Ultrasonic Electronics}}, pages = {{439 -- 440}}, title = {{{Fundamental Study on A Thickness-Shear Transformer using X-Cut Lithium Niobate}}}, volume = {{28}}, year = {{2007}}, } @article{9567, abstract = {{Numerical predictions of the forced vibration of a disk assembly including frictional effects between the shrouds are presented concerning engineering needs for the blade design process. Assuming a tuned disk assembly, numerical static, free, and then forced vibration analyses of a shrouded turbine blade measured in the spin pit are performed systematically. For the excitation forces of an air jet evaluated from the fairly linear behavior of the experimental blade resonance peaks, the reliability of the proposed approach is validated through the very close agreement of the computed and measured resonant peaks. These resonant peaks demonstrate either a fairly linear behavior or a nonlinear one like the jump effect of blade resonance amplitudes, or elastic impacts between the shrouds. Also, the damping performance for different contact configurations between the shrouds is numerically analyzed. These numerical results indicate that the shrouds generate higher frictional damping for small angles (0{\^a}30deg) between the circumferential direction and the normal vector to the contact surface.}}, author = {{Szwedowicz, J and Visser, R and Sextro, Walter and Masserey, P. A}}, issn = {{0889-504X}}, journal = {{Journal of Turbomachinery}}, number = {{1}}, pages = {{011002--011002}}, title = {{{On Nonlinear Forced Vibration of Shrouded Turbine Blades}}}, volume = {{130}}, year = {{2007}}, } @inproceedings{9532, author = {{Becker, C and Wedman, S and Hemsel, Tobias}}, booktitle = {{Proceedings of 2nd International Workshop on Piezoelectric Materials and Applications in Actuators}}, number = {{Band 180}}, pages = {{481}}, title = {{{Design and Construction of a 3D-Scanning-Laservibrometer}}}, year = {{2006}}, } @article{9533, abstract = {{The design of piezoelectric transducers is usually based on single-objective optimization only. In most practical applications of piezoelectric transducers, however, there exist multiple design objectives that often are contradictory to each other by their very nature. It is impossible to find a solution at which each objective function gets its optimal value simultaneously. Our design approach is to first find a set of Pareto-optimal solutions, which can be considered to be best compromises among multiple design objectives. Among these Pareto-optimal solutions, the designer can then select the one solution which he considers to be the best one. In this paper we investigate the optimal design of a Langevin transducer. The design problem is formulated mathematically as a constrained multiobjective optimization problem. The maximum vibration amplitude and the minimum electrical input power are considered as optimization objectives. Design variables involve continuous variables (dimensions of the transducer) and discrete variables (the number of piezoelectric rings and material types). In order to formulate the optimization problem, the behavior of piezoelectric transducers is modeled using the transfer matrix method based on analytical models. Multiobjective evolutionary algorithms are applied in the optimization process and a set of Pareto-optimal designs is calculated. The optimized results are analyzed and the preferred design is determined. }}, author = {{Fu, Bo and Hemsel, Tobias and Wallaschek, Jörg}}, issn = {{0041-624X}}, journal = {{Ultrasonics}}, keywords = {{Piezoelectric transducer}}, pages = {{e747 -- e752}}, title = {{{Piezoelectric transducer design via multiobjective optimization}}}, doi = {{10.1016/j.ultras.2006.05.087}}, volume = {{44, Supplement}}, year = {{2006}}, } @inproceedings{9534, author = {{Fu, Bo and Hemsel, Tobias and Wallaschek, Jörg}}, booktitle = {{Proceedings of 2nd International Workshop on Piezoelectric Materials and Applications in Actuators}}, number = {{Band 180}}, pages = {{223--228}}, title = {{{Multiobjective optimization of piezoelectric transducers using evolutionary algorithms}}}, year = {{2006}}, } @inproceedings{9535, author = {{Genzo, Alexander and Sextro, Walter}}, booktitle = {{Proceedings of ISMA - International conference on noise and vibration engineering}}, keywords = {{Noise, Vibration engineering}}, pages = {{51--52}}, title = {{{Dynamic Behaviour of Elastic Bodies Coupled by Extended Friction Contacts}}}, year = {{2006}}, } @inbook{9536, abstract = {{This paper presents a model for unsteady longitudinal slippage of a loaded rubber wheel. The aim of modelling was to calculate the dynamical contact behavior in a numerical efficient way. Further on, simulation results are compared to experimental data.}}, author = {{Gutzeit, F and Sextro, Walter and Kröger, Matthias}}, booktitle = {{Analysis and Simulation of Contact Problems}}, editor = {{Wriggers, Peter and Nackenhorst, Udo}}, isbn = {{978-3-540-31760-9}}, pages = {{261--270}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Unsteady rolling contact of rubber wheels}}}, doi = {{10.1007/3-540-31761-9_29}}, volume = {{27}}, year = {{2006}}, } @inproceedings{9537, author = {{Hemsel, Tobias and Henning, C and Kauczor, Christopher and Littmann, Walter}}, booktitle = {{Proceedings of 2nd International Workshop on Piezoelectric Materials and Applications in Actuators}}, number = {{Band 180}}, pages = {{183--186}}, title = {{{Powder coating fabrication by ultrasonic standing wave atomizer}}}, year = {{2006}}, }