@inproceedings{9856, author = {{Lenzen, Marco and Unger, Andreas and Wortberg, Johannes}}, publisher = {{SPE Antec}}, title = {{{2PC-Recu-Module for energy recovery at hydraulic driven injection molding machines}}}, year = {{2013}}, } @inproceedings{9858, abstract = {{In this contribution, we introduce a multiobjective optimization used to calculate safe optimal working points for a mechatronic system by including stochastic safety-critical signals in an objective function. Our application example consists of a linear drive for a rail-bound vehicle and an actuation unit. The linear drive's secondary part is fixed; the primary part is vehicle-mounted and can be adjusted vertically to account for deviations of the height of the secondary part. A small air gap between both parts improves efficiency, but increases the risk of a collision between the two parts. Using height data of the secondary part, a trajectory for the vertical adjustment of the primary part is calculated. However, unexpected deviations necessitate a readjustment of the air gap. The probability of such unexpected height deviations can be calculated from the readjustment data. The system is equipped with sensors to measure the air gap. Assuming that the sensor noise is normally distributed, noise characteristics are determined. Using this information and the probability distribution of unexpected height deviations, the probability of a collision is determined.T he sensor noise and the probability of a collision between both parts of the linear drive are included in the dynamical model of the system. Using multiobjective optimization, pareto-optimal working points for the controller of the air gap are obtained. By selecting an appropriate working point, safe operation can be ensured.}}, author = {{Meyer, Tobias and Hölscher, Christina and Menke, Michael and Sextro, Walter and Zimmer, Detmar}}, booktitle = {{Proc. Appl. Math. Mech.}}, pages = {{483--484}}, title = {{{Multiobjective Optimization including Safety of Operation Applied to a Linear Drive System}}}, doi = {{10.1002/pamm.201310234}}, volume = {{13}}, year = {{2013}}, } @inproceedings{9859, abstract = {{Self-optimizing mechatronic systems allow the adaptation of the system's behavior to the current situation. This can be used to actively adapt the behavior to the current degradation state of the system or of some of its components. To this end, the Multi-Level Dependability Concept has been developed. In this contribution, we show how the Multi-Level Dependability Concept has been applied to the active suspension module of an innovative rail-bound vehicle. For this module, the usage of control reconfiguration, which is a novel approach to exploit complex redundancy systems, is required. We show that by combining self-optimization with the possibilities given by control reconfiguration, the dependability of a complex mechatronic system can be greatly improved.}}, author = {{Meyer , Tobias and Henning Keßler, Jan and Sextro, Walter and Trächtler, Ansgar}}, booktitle = {{Proceedings of the Annual Reliability and Maintainability Symposium (RAMS)}}, title = {{{Increasing Intelligent Systems' Reliability by Using Reconfiguration}}}, doi = {{10.1109/RAMS.2013.6517636}}, year = {{2013}}, } @article{9860, abstract = {{Self-optimizing mechatronic systems offer possibilities well beyond those of traditional mechatronic systems. Among these is the adaptation of the system behavior to the current situation. To do so, they are able to choose from different working points, which are pre-calculated using multiobjective optimization and are thus Pareto-optimal with regard to the chosen objective functions. In this contribution, a method is presented that allows to continuously control the system degradation by adapting the behavior of a selfoptimizing system throughout its complete lifetime. The current remaining useful lifetime is estimated and then related to the spent lifetime and the desired useful lifetime. Using this information, a reliability-related objective is prioritized using a closed-loop control, which in turn is used to determine the working point of the self-optimizing system. This way, the desired useful lifetime can be achieved. To exemplify the setup of the controller structure and to demonstrate the adaptation of the system behavior, a dynamic model of a clutch system is used. It can be seen that the closed loop controller is able to correct for external perturbations, such as changed requirements, as well as changed system parameters. This way, the modeled system is able to achieve the desired lifetime reliably.}}, author = {{Meyer, Tobias and Sondermann-Wölke, Christoph and Kimotho, James Kuria and Sextro, Walter}}, journal = {{Chemical Engineering Transactions}}, pages = {{625--630}}, title = {{{Controlling the Remaining Useful Lifetime using Self-Optimization}}}, doi = {{10.3303/CET1333105}}, volume = {{33}}, year = {{2013}}, } @inproceedings{9861, abstract = {{Selbstoptimierende mechatronische Systeme bieten die Möglichkeit, ihr Verhalten an geänderte Umgebungsbedingungen anzupassen. Dazu werden beispielsweise redundante Strukturen genutzt, Reglerparameter angepasst oder Regelstrategien umgeschaltet. Dies kann auch genutzt werden, um die Zuverlässigkeit des Systems zu steigern. Zugleich entstehen aber durch die gesteigerte Komplexität dieser Systeme zusätzliche Risiken. Um sicherzustellen, dass das System dennoch die gestellten Anforderungen bezüglich der Zuverlässigkeit erfüllt, ist eine Modellierung des Gesamtsystems und anschließende Zuverlässigkeitsbewertung notwendig. Dies ist aufgrund der situationsabhängigen Verhaltensanpassung und des nicht intuitiv vorhersehbaren Verhaltens jedoch nicht mit klassischen Verfahren möglich. Ein Modellierungsverfahren, das diese Eigenschaften abbilden kann, ist LARES (LAnguage for REconfigurable dependable Systems). Die Anwendung von LARES zur Bewertung der Zuverlässigkeit eines selbstoptimierenden Systems wird anhand des Feder-Neige-Moduls gezeigt. Es ist eine Baugruppe der Fahrzeuge eines innovativen Bahnsystems, der RailCabs. Das Feder-Neige-Modul dient dazu, unerwünschte Schwingungen des Fahrzeugaufbaus zu minimieren. Mit LARES können die Hardware-Komponenten des Systems, ihre in Abhängigkeit von der aktuellen Situation veränderten Belastungen sowie die nicht-deterministische Verhaltensadaption modelliert werden.}}, author = {{Meyer, Tobias and Sondermann-Wölke, Christoph and Sextro, Walter and Riedl, Martin and Gouberman, Alexander and Siegle, Markus}}, booktitle = {{9. Paderborner Workshop Entwurf mechatronischer Systeme}}, editor = {{Gausemeier, Jürgen and Dumitrescu, Roman and Rammig, Franz and Schäfer, Wilhelm and Trächtler, Ansgar}}, pages = {{161--174}}, publisher = {{Heinz Nixdorf Institut, Universität Paderborn}}, title = {{{Bewertung der Zuverlässigkeit selbstoptimierender Systeme mit dem LARES-Framework}}}, year = {{2013}}, } @misc{9863, abstract = {{The 9th International Workshop on Piezoelectric Materials and Applications in Actuators (IWPMA 2012) was successfully held on 22–25 April 2012 in Hirosaki, Japan. The general chair was Prof. M.K. Kurosawa from the Tokyo Institute of Technology, Japan. In the past, Korea, Germany, Turkey, China, and USA have hosted the annual conference, but this was the first time for the annual IWPMA conference to be held in Japan. The IWPMA 2012 was organized as a joint symposium with JTTAS Smart Actuator/Sensor Study Committee and ICAT International Actuator Symposium. More than 150 people from the world (12 countries) participated and had fruitful discussions with 138 presentations including 11 invited talks. In addition to piezoelectric materials and piezoelectric actuators, the presentation topics were expanded to include solid-state actuators, energy harvesting, multifunctional materials, and other current important issues. It is our honor to pronounce that the “Sensors and Actuators A” journal has published this special issue on the IWPMA 2012 including the best 25 contributions. This issue covers the functional materials, such as piezoelectric and magnetostrictive materials, and their applications. However, for the innovative devices, various ideas concerning materials, mechanisms, designs, fabrication process, and control-systems are also required to be organically combined. From the view of this concept, we believe the published 25 papers can excite the researcher's intellectual curiosity concerning these issues and can serve as the driving force for further breakthroughs. Please enjoy the latest research results selected by our editor team. Finally, we appreciate all participants in the IWPMA 2012 and the devoted reviewers for the publication. We hope that the papers in this special issue will open up the next researches, which will be presented in the future IWPMA conferences.}}, booktitle = {{Sensors and Actuators A: Physical}}, editor = {{Morita, Takeshi and Hemsel, Tobias and Ijima, T. and Jeong, D. Y. and Kanda, T. and Twiefel, Jens and Uzgur, E. and Lallart, M.}}, location = {{Hirosaki}}, pages = {{1--172}}, publisher = {{Elsevier}}, title = {{{Selected Papers from the 9th International Workshop on Piezoelectric Materials and Applications in Actuators}}}, doi = {{10.1016/j.sna.2013.06.017}}, volume = {{200}}, year = {{2013}}, } @article{9866, abstract = {{The hydrothermal method utilizes a solution-based chemical reaction to synthesize piezoelectric thin films and powders. This method has a number of advantages, such as low-temperature synthesis, and high purity and high quality of the product. In order to promote hydrothermal reactions, we developed an ultrasonic assisted hydrothermal method and confirmed that it produces dense and thick lead--zirconate--titanate (PZT) films. In the hydrothermal method, a crystal growth process follows the nucleation process. In this study, we verified that ultrasonic irradiation is effective for the nucleation process, and there is an optimum irradiation period to obtain thicker PZT films. With this optimization, a 9.2-$\mu$ m-thick PZT polycrystalline film was obtained in a single deposition process. For this film, ultrasonic irradiation was carried out from the beginning of the reaction for 18 h, followed by a 6 h deposition without ultrasonic irradiation. These results indicate that the ultrasonic irradiation mainly promotes the nucleation process.}}, author = {{Ohta, Kanako and Isobe, Gaku and Bornmann, Peter and Hemsel, Tobias and Morita, Takeshi}}, issn = {{0041-624X}}, journal = {{Ultrasonics}}, keywords = {{Piezoelectric material}}, number = {{4}}, pages = {{837 -- 841}}, title = {{{Study on optimizing ultrasonic irradiation period for thick polycrystalline PZT film by hydrothermal method}}}, doi = {{10.1016/j.ultras.2012.12.003}}, volume = {{53}}, year = {{2013}}, } @article{9867, abstract = {{We report the piezoelectric properties of CuO-doped hydrothermal (K,Na)NbO3 ceramics that can be applied as hard-type lead-free piezoelectric ceramics. To date, we have succeeded in synthesizing high-quality KNbO3 and NaNbO3 powders by the hydrothermal method, which is based on an ionic reaction at high temperature (around 210 $\,^{\circ}$C) and pressure. Increasing both the piezoelectric constant d and the mechanical quality factor (Qm) is important for resonance-type piezoelectric devices, such as ultrasonic motors and transformers. CuO doping into hydrothermal (K,Na)NbO3 ceramics was examined to realize hard-type lead-free piezoelectric ceramics. By doping with 1.2 mol \% CuO, Qm was increased and the dielectric loss (tan δ) was decreased to 0.5\%. The grain size was also influenced by the amount of CuO doping, which indicates that Qm is related to the density. To achieve a higher Qm value, the grain size is required to be less than 5 µm; however, excessive CuO doping leads to anomalous grain growth. Optimal piezoelectric properties were obtained for 1.2 mol \% CuO-doped (K,Na)NbO3; k31 = 0.32, d31 = -44 pC/N, Qm (radial) = 959, and tan δ= 0.5\%. These characteristics showed that CuO doping with hydrothermal powders is effective for obtaining hard-type ceramics, and the mechanical quality factor is more than ten times higher than that of nondoped hydrothermal (K,Na)NbO3 ceramics. Therefore, compared with the conventional solid-state method, we could succeed in obtaining hard-type ceramics by a simple and short process.}}, author = {{Yokouchi, Yuriko and Maeda, Takafumi and Bornmann, Peter and Hemsel, Tobias and Morita, Takeshi}}, journal = {{Japanese Journal of Applied Physics}}, number = {{7S}}, title = {{{Piezoelectric Properties of CuO-Doped (K,Na)NbO3 Lead-Free Ceramics Synthesized with Hydrothermal Powders}}}, doi = {{10.7567/JJAP.52.07HB03}}, volume = {{52}}, year = {{2013}}, } @phdthesis{9792, abstract = {{''Energy Harvester`` wandeln Umgebungsenergie in nützliche elektrische Energie. Zur Berechnung der elektromechanischen Charakteristik eines piezoelektrischen ''Energy Harvesters" wird ein auf Materialeigenschaften, Geometrie und Randbedingungen basierendes analytisches Modell vorgestellt. Dieses dient als Basis für ein weiteres Modell, welches den Betrieb eines autonomen Systems beschreibt. Die theoretischen Arbeiten werden mit Laborversuchen validiert. Es zeigt sich, dass der piezoelektrische Harvester im eingeschwungenen Zustand durch den Gleichrichtungsvorgang zwei abwechselnde Lastzustände erfährt. Dies führt zu nichtlinearem Verhalten des Harvesters, besonders wenn die angeschlossene Last eine geringe Impedanz hat. Desweiteren zeigen die Ergebnisse, dass ein solches autonomes System effizient arbeitet, wenn es an eine Last mit hoher Impedanz angeschlossen ist und bei einer der Antiresonanzfrequenz des piezoelektrischen Harvesters entsprechenden Frequenz angeregt wird.Das Modell des autonomen Systems wird auf ein System mit mehreren piezoelektrischen Wandlern erweitert. Zur praktischen Implementierung eines solchen Systems wird eine Technik zur Frequenzeinstellung eingeführt, da die optimalen Betriebsfrequenzen der einzelnen Wandler aufeinander abgestimmt werden müssen. Die Einstellung erfolgt, indem die Entfernung zwischen zwei Permanentmagneten und damit deren Anziehungskraft, welche die Steifigkeit des Harvesters beeinflusst, angepasst wird. Diese Technik zur Frequenzeinstellung wird modelliert und experimentell validiert. Die Ergebnisse zeigen, dass die Frequenzeinstellung mittels Permanentmagneten eine einfache und zugleich effektive Lösung für das Problem der Frequenzanpassung piezoelektrischer ''Energy Harvester" darstellt. Energy harvesters convert ambient energy into useful electrical energy. An analytical model for calculating the electromechanical characteristics of a piezoelectric harvester based on the material properties, geometry and boundary conditions is presented. This model is the basis for a further model which describes the operation of an autonomous system powered by a piezoelectric harvester. This theoretical work is validated by corresponding laboratory experiments. It is found that, in steady-state operation, the piezoelectric harvester experiences two alternating load conditions due to the rectification process. These load conditions make the system behave nonlinearly, especially if the connected electrical load is of low impedance. Furthermore, the results show that such an autonomous system works efficiently if it is connected to a high impedance load and excited at a frequency matching the anti-resonance frequency of the piezoelectric harvester.The model of an autonomous system is extended to describe a system with multiple piezoelectric transducers. For implementing such a system, the optimum operation frequencies of the individual transducers must be adjusted. Therefore, a frequency tuning method is introduced. The tuning is accomplished by adjusting the distance between two permanent magnets and thus changing the attracting force between them in order to affect the structural stiffness of the harvester. This tuning method is modeled and validated experimentally. The results show that frequency tuning using permanent magnets is a simple and effective solution for the frequency adjustment of piezoelectric energy harvesters.}}, author = {{Al-Ashtari, Waleed}}, publisher = {{Shaker}}, title = {{{Model based enhancement of an autonomous system with a piezoelectric harvester}}}, year = {{2013}}, } @article{9781, abstract = {{A piezoelectric energy harvester is an electromechanical device that converts ambient mechanical vibration into electric power. Most existing vibration energy harvesting devices operate effectively at a single frequency only, dictated by the design of the device. This frequency must match the frequency of the host structure vibration. However, real world structural vibrations rarely have a specific constant frequency. Therefore, piezoelectric harvesters that generate usable power across a range of exciting frequencies are required to make this technology commercially viable. Currently known harvester tuning techniques have many limitations, in particular they miss the ability to work during harvester operation and most often cannot perform a precise tuning. This paper describes the design and testing of a vibration energy harvester with tunable resonance frequency, wherein the tuning is accomplished by changing the attraction force between two permanent magnets by adjusting the distance between the magnets. This tuning technique allows the natural frequency to be manipulated before and during operation of the harvester. Furthermore the paper presents a physical description of the frequency tuning effect. The experimental results achieved with a piezoelectric bimorph fit the calculated results very well. The calculation and experimental results show that using this tuning technique the natural frequency of the harvester can be varied efficiently within a wide range: in the test setup, the natural frequency of the piezoelectric bimorph could be increased by more than 70\%.}}, author = {{Al-Ashtari, Waleed and Hunstig, Matthias and Hemsel, Tobias and Sextro, Walter}}, journal = {{Smart Materials and Structures}}, number = {{3}}, pages = {{035019}}, title = {{{Frequency tuning of piezoelectric energy harvesters by magnetic force}}}, volume = {{21}}, year = {{2012}}, } @article{9782, abstract = {{Piezoelectric structures are nowadays used in many different applications. A better understanding of the influence of material properties and geometrical design on the performance of these structures helps to develop piezoelectric structures specifically designed for their application. Different equivalent circuits have been introduced in the literature to investigate the behaviour of piezoelectric transducers. The model parameters are usually determined from measurements covering the characteristic frequencies of the piezoelectric transducer. This article introduces an analytical technique for calculating the mechanical and electrical equivalent system parameters and characteristic frequencies based on material properties and geometry for a cantilever bimorph structure. The model is validated by measurements using a cantilever bimorph and fits the experimental results better than previous models. The model gives a full set of piezoelectric transducer parameters and is therefore well suited for further theoretical investigations of piezoelectric transducers for different applications. The results also show that even small manufacturing tolerances have a considerable effect on the system parameters and characteristic frequencies. This might lead to intolerable deviations, especially in dynamic applications and should be avoided by careful design and production.}}, author = {{Al-Ashtari, Waleed and Hunstig, Matthias and Hemsel, Tobias and Sextro, Walter}}, journal = {{Journal of Intelligent Material Systems and Structures}}, number = {{1}}, pages = {{15--23}}, title = {{{Analytical determination of characteristic frequencies and equivalent circuit parameters of a piezoelectric bimorph}}}, doi = {{10.1177/1045389X11430742}}, volume = {{23}}, year = {{2012}}, } @inproceedings{9783, abstract = {{To optimize the ultrasound irradiation for cavitation based ultrasound applications like sonochemistry or ultrasound cleaning, the correlation between cavitation intensity and the resulting effect on the process is of interest. Furthermore, changing conditions like temperature and pressure result in varying acoustic properties of the liquid. That might necessitate an adaption of the ultrasound irradiation. To detect such changes during operation, process monitoring is desired. Labor intensive processes, that might be carried out for several hours, also require process monitoring to increase their reliability by detection of changes or malfunctions during operation. In some applications cavitation detection and monitoring can be achieved by the application of sensors in the sound field. Though the application of sensors is possible, this necessitates modifications on the system and the sensor might disturb the sound field. In other applications harsh, process conditions prohibit the application of sensors in the sound field. Therefore alternative techniques for cavitation detection and monitoring are desired. The applicability of an external microphone and a self-sensing ultrasound transducer for cavitation detection were experimentally investigated. Both methods were found to be suitable and easily applicable.}}, author = {{Bornmann, Peter and Hemsel, Tobias and Sextro, Walter and Maeda, Takafumi and Morita, Takeshi}}, booktitle = {{Ultrasonics Symposium (IUS), 2012 IEEE International}}, issn = {{1948-5719}}, keywords = {{cavitation, chemical reactors, microphones, process monitoring, reliability, ultrasonic applications, ultrasonic waves, acoustic properties, cavitation based ultrasound applications, cavitation intensity, change detection reliability, external microphone, malfunction detection reliability, nonperturbing cavitation detection, nonperturbing cavitation monitoring, process monitoring, self-sensing ultrasound transducer, sonochemical reactors, sonochemistry, ultrasound cleaning, ultrasound irradiation, Acoustics, Liquids, Monitoring, Sensors, Sonar equipment, Transducers, Ultrasonic imaging}}, pages = {{1141--1144}}, title = {{{Non-perturbing cavitation detection / monitoring in sonochemical reactors}}}, doi = {{10.1109/ULTSYM.2012.0284}}, year = {{2012}}, } @inproceedings{9784, abstract = {{Piezoelectric inertia motors use the inertia of a body to drive it by means of a friction contact in a series of small steps. These motors can operate in ``stick-slip'' or ``slip-slip'' mode, with the fundamental frequency of the driving signal ranging from several Hertz to more than 100 kHz. To predict the motor characteristics, a Coulomb friction model is sufficient in many cases, but numerical simulation requires microscopic time steps. This contribution proposes a much faster simulation technique using one evaluation per period of the excitation signal. The proposed technique produces results very close to those of timestep simulation for ultrasonics inertia motors and allows direct determination of the steady-state velocity of an inertia motor from the motion profile of the driving part. Thus it is a useful simulation technique which can be applied in both analysis and design of inertia motors, especially for parameter studies and optimisation.}}, author = {{Hunstig, Matthias and Hemsel, Tobias and Sextro, Walter}}, booktitle = {{Ultrasonics Symposium (IUS), 2012 IEEE International}}, issn = {{1948-5719}}, keywords = {{friction, ultrasonic motors, Coulomb friction model, efficient simulation technique, friction contact, high-frequency piezoelectric inertia motor, motor characteristics prediction, numerical simulation, slip-slip mode, stick-slip mode, time-step simulation, ultrasonic inertia motor, Acceleration, Acoustics, Actuators, Computational modeling, Friction, Numerical models, Steady-state}}, pages = {{277--280}}, title = {{{An efficient simulation technique for high-frequency piezoelectric inertia motors}}}, doi = {{10.1109/ULTSYM.2012.0068}}, year = {{2012}}, } @inproceedings{9785, abstract = {{Hydrothermal method enables to synthesize high quality piezoelectric materials. To shorten the reaction time and to get higher quality materials, we propose an ultrasonic irradiation to the solution during the hydrothermal method. We named it ultrasonic assisted hydrothermal method (UAHTM). We have synthesized lead-free piezoelectric material and PZT thin film and the effect of UAHTM have been confirmed. In this study, we tried to improve UAHTM. First, to generate powerful and stable ultrasonic irradiation at high temperature on UAHTM, we developed a new transducer using LiNbO3 single crystal. Second, to prevent contamination to the materials, A Teflon cover on the tip of transducer was attached.}}, author = {{Isobe, Gaku and Ageba, Ryo and Maeda, Takafumi and Bornmann, Peter and Hemsel, Tobias and Morita, Takeshi}}, booktitle = {{AIP Conference Proceedings}}, editor = {{B. J. Linde, Bogumil and Paczkowski, Jacek and Ponikwicki, Nikodem}}, keywords = {{contamination, lead compounds, piezoelectric materials, piezoelectric thin films, piezoelectric transducers, ultrasonic effects}}, number = {{1}}, pages = {{569--572}}, publisher = {{AIP}}, title = {{{Synthesis of piezoelectric materials by ultrasonic assisted hydrothermal method}}}, doi = {{10.1063/1.3703251}}, volume = {{1433}}, year = {{2012}}, } @article{9786, abstract = {{Self-optimizing mechatronic systems are a new class of technical systems. On the one hand, new challenges regarding dependability arise from their additional complexity and adaptivity. On the other hand, their abilities enable new concepts and methods to improve the dependability of mechatronic systems. This paper introduces a multi-level dependability concept for selfoptimizing mechatronic systems and shows how probabilistic planning can be used to improve the availability and reliability of systems in the operating phase. The general idea to improve the availability of autonomous systems by applying probabilistic planning methods to avoid energy shortages is exemplified on the example of an innovative railway vehicle.}}, author = {{Klöpper, Benjamin and Sondermann-Wölke, Christoph and Romaus, Christoph}}, journal = {{Journal of Robotics and Mechatronics}}, keywords = {{self-optimizing systems, dependability, probabilistic planning, energy management}}, number = {{1}}, pages = {{5--15}}, title = {{{Probabilistic Planning for Predictive Condition Monitoring and Adaptation Within the Self-Optimizing Energy Management of an Autonomous Railway Vehicle}}}, volume = {{24}}, year = {{2012}}, } @inproceedings{9787, author = {{Kohl, Sergej and Sextro, Walter and Zuber, Armin}}, booktitle = {{8. Tag des Fahrwerks, Aachen, 2012}}, pages = {{38--60}}, title = {{{Benteler Vehicle Dynamics -- Fahrdynamikentwicklung basierend auf einer neuen Auslegungstheorie}}}, year = {{2012}}, } @inproceedings{9788, abstract = {{A hydrothermal method utilizes a crystallization process in the solution so that the pure and high-quality powders can be realized. Sintering from the hydrothermal KNbO3 and NaNbO3 powders, a high-dense lead-free piezoelectric (K,Na)NbO3 ceramics could be obtained (density: 98.8\%). Concerning about the g33 constant, high value as large as commercial PZT ceramics was measured. Therefore, the hydrothermal (K,Na)NbO3 ceramics is usable for the sensors and the energy harvesting devices. To demonstrate the (K,Na)NbO3 ceramics, a hydrophone sensor was fabricated and evaluated.}}, author = {{Maeda, Takafumi and Bornmann, Peter and Hemsel, Tobias and Morita, Takeshi}}, booktitle = {{Ultrasonics Symposium (IUS), 2012 IEEE International}}, issn = {{1948-5719}}, keywords = {{crystallisation, hydrophones, piezoceramics, potassium compounds, powder technology, powders, sensors, sintering, sodium compounds, (K0.48Na0.52)NbO3, KNbO3 powder, NaNbO3 powder, crystallization, energy harvesting devices, g33 constant, hydrophone sensor, hydrothermal lead-free (K0.48Na0.52)NbO3 ceramics, hydrothermal method, piezoelectric applications, sintering, Materials, Transducers}}, pages = {{194--195}}, title = {{{Piezoelectric applications of hydrothermal lead-free (K0.48Na0.52)NbO3 ceramics}}}, doi = {{10.1109/ULTSYM.2012.0048}}, year = {{2012}}, } @article{9789, abstract = {{[$Li_x(Na_0.52K_0.48)_1-x]NbO_3 (0 \leq x \leq 0.091)$ ceramics were synthesized using hydrothermal powders and the lithium doping content was controlled to optimize their piezoelectric properties. The raw KNbO$_3$ and NaNbO$_3$ powders were obtained separately by a hydrothermal method and LiNbO$_3$ powders were prepared by milling a commercial LiNbO$_3$ single crystal. These powders were mixed with ethanol at a molar ratio LiNbO$_3$: ($Na_0.52K_0.48$)NbO$_3 = x : 1-x$. The synthesized powders were sintered at 1060--1120 $\,^{\circ}$C for 2 h. We succeeded in obtaining highly dense [$Li_x(Na_0.52K_0.48)_1-x]NbO_3$ ceramics using hydrothermal powder. The X-ray diffraction patterns revealed that the crystal phase changed from orthorhombic to tetragonal at around x = 0.06. At this morphotropic phase boundary (MPB), the c/a ratio changed from 1.016 to 1.024 and the highest piezoelectric constant was obtained with the chemical component of [$Li_x(Na_0.52K_0.48)_1-x]NbO_3$. The obtained piezoelectric properties were as follows: $k_33 = 0.51, \epsilon 33^T/ \epsilon _0 = 836$ , $c_33^E = 46$ GPa, $d_33 = 203$ pC/N, and $T_c = 482 $\,^{\circ}$C$.}}, author = {{Maeda, Takafumi and Hemsel, Tobias and Morita, Takeshi}}, journal = {{Japanese Journal of Applied Physics}}, pages = {{09MD08}}, publisher = {{The Japan Society of Applied Physics}}, title = {{{Piezoelectric Properties of Li-Doped (K0.48Na0.52)NbO3 Ceramics Synthesized Using Hydrothermally-Derived KNbO3 and NaNbO3 Fine Powders}}}, doi = {{10.1143/JJAP.51.09MD08}}, volume = {{51}}, year = {{2012}}, } @inproceedings{9791, abstract = {{The rapid development of communication and information technology opens up fascinating perspectives, which go far beyond the state of the art in mechatronics: mechatronic systems with inherent partial intelligence. These so called self-optimizing systems adapt their objectives and behavior autonomously and flexibly to changing operating conditions. On the one hand, securing the dependability of such systems is challenging due to their complexity and non-deterministic behavior. On the other hand, self-optimization can be used to increase the dependability of the system during its operation. However, it has to be ensured, that the self-optimization works dependable itself. To cope with these challenges, the multi-level dependability concept was developed. It enables predictive condition monitoring, influences the objectives of the system and determines suitable means to improve the system's dependability during its operation. In this contribution we introduce a procedure for the conceptual design of an advanced condition monitoring based on the system's principle solution. The principle solution describes the principal operation mode of the system and its desired behavior. It is modeled using the specification technique for the domain-spanning description of the principle solution of a self-optimizing system and consists of a coherent system of eight partial models (e.g. requirements, active structure, system of objectives, behavior, etc.). The partial models are analyzed separately in order to derive the components of the multi-level dependability concept. In particular, the reliability analysis of the partial model active structure is performed to identify the system elements to be monitored and parameters to be measured. The principle solution is extended accordingly: e.g. with system elements required for the realization of the dependability concept. The advantages of the method are shown on the self-optimizing guidance module of a railroad vehicle.}}, author = {{Sondermann-Wölke , Christoph and Meyer, Tobias and Dorociak, Rafal and Gausemeier, Jürgen and Sextro, Walter}}, booktitle = {{Proceedings of the 11th International Probabilistic Safety Assessment and Management Conference (PSAM11) and The Annual European Safety and Reliability Conference (ESREL2012)}}, keywords = {{Mechatronic Systems, Principle Solution, Condition Monitoring, Conceptual Design}}, title = {{{Conceptual Design of Advanced Condition Monitoring for a Self-Optimizing System based on its Principle Solution}}}, year = {{2012}}, } @article{9806, abstract = {{Piezoelectric inertia motors, also known as ``stick-slip-drives'', use the inertia of a body to drive it by means of a friction contact in small steps. While these steps normally involve stiction and sliding, the motors can also operate in ``slip-slip'' mode without any phase of static friction. In this contribution, a one degree of freedom model of an inertia motor driven by an ideal actuator is analysed. Start-up and constant velocity operation of the motor are investigated and appropriate quantities to compare ``stick-slip'' and ``slip-slip'' operation are determined. Different aspects such as velocity, uniformity of motion, load capacity, robustness, efficiency, and wear are considered. The analysis allows both modes to be applied advantageously in different applications and can widen the field of application of piezoelectric inertia motors. Motor designers are enabled to choose the appropriate mode of operation and the best drive parameters for their individual applications.}}, author = {{Hunstig, Matthias and Hemsel, Tobias and Sextro, Walter}}, journal = {{ACTUATOR 2012 Conference Proceedings}}, keywords = {{Piezoelectric Inertia Motors, Drive Signals, Stick-slip, Slip-slip}}, pages = {{761--764}}, title = {{{Analysis of different operation modes for inertia motors}}}, year = {{2012}}, }