TY - CONF AB - 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. AU - Isobe, Gaku AU - Ageba, Ryo AU - Maeda, Takafumi AU - Bornmann, Peter AU - Hemsel, Tobias AU - Morita, Takeshi ED - B. J. Linde, Bogumil ED - Paczkowski, Jacek ED - Ponikwicki, Nikodem ID - 9785 IS - 1 KW - contamination KW - lead compounds KW - piezoelectric materials KW - piezoelectric thin films KW - piezoelectric transducers KW - ultrasonic effects T2 - AIP Conference Proceedings TI - Synthesis of piezoelectric materials by ultrasonic assisted hydrothermal method VL - 1433 ER - TY - JOUR AB - 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. AU - Klöpper, Benjamin AU - Sondermann-Wölke, Christoph AU - Romaus, Christoph ID - 9786 IS - 1 JF - Journal of Robotics and Mechatronics KW - self-optimizing systems KW - dependability KW - probabilistic planning KW - energy management TI - Probabilistic Planning for Predictive Condition Monitoring and Adaptation Within the Self-Optimizing Energy Management of an Autonomous Railway Vehicle VL - 24 ER - TY - CONF AU - Kohl, Sergej AU - Sextro, Walter AU - Zuber, Armin ID - 9787 T2 - 8. Tag des Fahrwerks, Aachen, 2012 TI - Benteler Vehicle Dynamics -- Fahrdynamikentwicklung basierend auf einer neuen Auslegungstheorie ER - TY - CONF AB - 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. AU - Maeda, Takafumi AU - Bornmann, Peter AU - Hemsel, Tobias AU - Morita, Takeshi ID - 9788 KW - crystallisation KW - hydrophones KW - piezoceramics KW - potassium compounds KW - powder technology KW - powders KW - sensors KW - sintering KW - sodium compounds KW - (K0.48Na0.52)NbO3 KW - KNbO3 powder KW - NaNbO3 powder KW - crystallization KW - energy harvesting devices KW - g33 constant KW - hydrophone sensor KW - hydrothermal lead-free (K0.48Na0.52)NbO3 ceramics KW - hydrothermal method KW - piezoelectric applications KW - sintering KW - Materials KW - Transducers SN - 1948-5719 T2 - Ultrasonics Symposium (IUS), 2012 IEEE International TI - Piezoelectric applications of hydrothermal lead-free (K0.48Na0.52)NbO3 ceramics ER - TY - JOUR AB - [$Li_x(Na_0.52K_0.48)_1-x]NbO_3 (0 \leq x \leq 0.091)$ 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$. AU - Maeda, Takafumi AU - Hemsel, Tobias AU - Morita, Takeshi ID - 9789 JF - Japanese Journal of Applied Physics TI - Piezoelectric Properties of Li-Doped (K0.48Na0.52)NbO3 Ceramics Synthesized Using Hydrothermally-Derived KNbO3 and NaNbO3 Fine Powders VL - 51 ER - TY - CONF AB - 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. AU - Sondermann-Wölke , Christoph AU - Meyer, Tobias AU - Dorociak, Rafal AU - Gausemeier, Jürgen AU - Sextro, Walter ID - 9791 KW - Mechatronic Systems KW - Principle Solution KW - Condition Monitoring KW - Conceptual Design T2 - Proceedings of the 11th International Probabilistic Safety Assessment and Management Conference (PSAM11) and The Annual European Safety and Reliability Conference (ESREL2012) TI - Conceptual Design of Advanced Condition Monitoring for a Self-Optimizing System based on its Principle Solution ER - TY - JOUR AB - 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. AU - Hunstig, Matthias AU - Hemsel, Tobias AU - Sextro, Walter ID - 9806 JF - ACTUATOR 2012 Conference Proceedings KW - Piezoelectric Inertia Motors KW - Drive Signals KW - Stick-slip KW - Slip-slip TI - Analysis of different operation modes for inertia motors ER - TY - JOUR AB - Aiming to diminish the reflection losses of glass covered light harvesting devices, the optical reflectivity of nanostructured glass surfaces is studied theoretically and experimentally. The work is inspired by the nanoscale roughness of insect eyes, which is tried to be replicated on a technical glass surface. To this end, the reflectivity of glass surfaces with topographies represented by linear, parabolic and Fermishaped glass/air fill factor profiles is calculated for normal incidence. It is shown that using the latter ones, an almost complete suppression of reflections can be achieved. A simple, self-organization technique to create such Fermi-shaped filling factor profiles in glass experimentally is also presented. AU - Achtelik, J. AU - Sievers, W. AU - Lindner, Jörg ID - 4095 IS - 9 JF - Materials Science and Engineering: B SN - 0921-5107 TI - Biomimetic approaches to create anti-reflection glass surfaces for solar cells using self-organizing techniques VL - 178 ER - TY - JOUR AB - We report on the molecular beam epitaxy growth of cubic GaN on 3C–SiC (001) nanostructures. Transmission electron microscopy (TEM) studies show phase-pure cubic GaN crystals with a low defect density on top of the post shaped 3C–SiC nanostructures and GaN grown on their sidewalls, which is dominated by {111} planar defects. The nanostructures, aligned parallel and perpendicular to the [110] directions of the substrate, are located in anti-phase domains of the 3C–SiC/Si (001) substrate. These anti-phase domains strongly influence the optimum growth of GaN layers in these regions. TEM measurements demonstrate a different stacking fault density in the cubic GaN epilayer in these areas. AU - Kemper, R.M. AU - Hiller, L. AU - Stauden, T. AU - Pezoldt, J. AU - Duschik, K. AU - Niendorf, T. AU - Maier, H.J. AU - Meertens, D. AU - Tillmann, K. AU - As, D.J. AU - Lindner, Jörg ID - 4104 JF - Journal of Crystal Growth SN - 0022-0248 TI - Growth of cubic GaN on 3C–SiC/Si (001) nanostructures VL - 378 ER - TY - JOUR AB - Two methods to create biomimetic anti-reflection nanostructures in ordinary glass microscope object slides are presented. One technique is based on a nanosphere lithography process combined with physical vapour deposition of nickel and reactive ion etching (RIE). The other uses plasma induced dewetting of a smooth nickel surface. The amount of reflected light was measured and a method to simulate the reflectivity from an atomic force microscopy (AFM) topography scan of the glass surface is presented. The reflectivity for visible light at normal incidence was reduced to 20-50 % of the original value with both methods and the simulation gives results in good agreement to the measurement. AU - Achtelik, Jörn AU - Kemper, Ricarda M. AU - Sievers, Werner AU - Lindner, Jörg ID - 4114 JF - MRS Proceedings SN - 1946-4274 TI - Self-Organized Nanostructure Formation for Anti-Reflection Glass Surfaces VL - 1389 ER -