TY - THES A1 - Knopf, Christoph T1 - Methodik zur Analyse der elektrischen Feldverteilung und thermischer Vorgänge bei der bipolaren transurethralen Resektion N2 - Die transurethrale Resektion der Prostata (TURP) ist ein Verfahren der Elektrochirurgie innerhalb der Urologie. Thema der Arbeit ist die Entwicklung einer Methodik für realitätsnahe vergleichende Untersuchungen der elektrothermischen Vorgänge um Resektoskope zur bipolaren TURP. Die Relevanz dieses Themas liegt in der aktuellen Diskussion, ob elektrothermische Verletzungen eine mögliche Ursache urethraler Komplikationen darstellen. In diesem Kontext sind nicht die Vorgänge an der Resektionselektrode sondern in nicht behandelten Arealen des Operationsgebiets von Interesse. Bisher durchgeführte Untersuchungen konzentrieren sich auf monopolare Systeme. Untersuchte bipolare Elektrodenanordnungen unterscheiden sich allerdings von heutigen bipolaren Resektoskopen. Die vorhandenen Erkenntnisse sind deshalb nur äußerst eingeschränkt anwendbar. Informationen zu thermischen Vorgängen bezüglich Spätkomplikationen liegen nicht vor. Der gewählte Ansatz aus messtechnischer Bestimmung der 3D Potentialverteilung ex situ sowie modellbasierter und numerischer Analyse der sich daraus ergebenden 3D Verlustleistungsdichteverteilung und der darauf beruhenden Temperaturberechnung im operationsnahen Gewebe ermöglicht ein auf die Realität übertragbares Ergebnis. Die berechnete Temperatur dient des Weiteren als Grundlage einer medizinischen Einschätzung hinsichtlich des Potentials elektrothermischer Verletzungen. Ergebnis der Arbeit ist, dass vergleichende Untersuchungen bipolarer Resektoskope mit der entwickelten Methodik durchführbar sind. Für die untersuchte bipolare Elektrodenanordnung erscheinen elektrothermische Verletzungen als Ursache urethraler Strikturen bei konservativer Betrachtung und unter durchschnittlichen Operationsbedingungen ohne intraoperative Komplikationen unwahrscheinlich. KW - Feldverteilung KW - thermische Vorgänge KW - bipolare transurethrale Resektion Y1 - 2014 UR - http://d-nb.info/1056056851 SN - 978-3-84403030-3 N1 - Zugl.: Chemnitz, Techn. Univ., Diss., 2014 PB - Shaker ER - TY - JOUR A1 - Prall, Christoph A1 - Erni, Daniel A1 - Rueter, Dirk T1 - Analysis of the Efficient High-Temperature In Situ Photoluminescence from GaN Layers during Epitaxial Growth JF - Condensed matter N2 - Photoluminescence (PL) in GaN or InGaN layers monitored during epitaxial growth at high temperatures permits a quasi-continuous in situ characterization of opto-electronic properties. Therefore, epitaxial parameters can now be optimized at the earliest possible stage. A pulsed and high-power UV laser was required for PL excitation at high temperatures. Herein, the underlying nonlinear mechanism was studied via time-resolved PL experiments and rate equation-based modeling. A temperature-activated and saturable path for quenching over defects was identified. Beyond the saturation threshold, reasonably-intensive PL sets in. At high temperatures not only is the near band gap-PL present, but also—as a new observation—a defect-assisted PL emerges. Apart from these specific electronic transitions in high-temperature PL of GaN, a simple, but reasonably predictive model of the luminescent thin film has been set up to track down interference fringes in the PL spectra. It is worth mentioning that the spectral PL modulation (aiming at the Purcell effect) is often mixed up with ordinary Fabry–Pérot interference. A distinction has become key to properly analyze the spectral signatures of high-temperature PL in order to provide a reliable in situ characterization of GaN layers during epitaxial growth. Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1393-opus4-1290 VL - 2 IS - 19 ER - TY - JOUR A1 - Rüter, Dirk T1 - Experimental Demonstration and Circuitry for a Very Compact Coil-Only Pulse Echo EMAT JF - sensors N2 - This experimental study demonstrates for the first time a solid-state circuitry and design for a simple compact copper coil (without an additional bulky permanent magnet or bulky electromagnet) as a contactless electromagnetic acoustic transducer (EMAT) for pulse echo operation at MHz frequencies. A pulsed ultrasound emission into a metallic test object is electromagnetically excited by an intense MHz burst at up to 500 A through the 0.15 mm filaments of the transducer. Immediately thereafter, a smoother and quasi “DC-like” current of 100 A is applied for about 1 ms and allows an echo detection. The ultrasonic pulse echo operation for a simple, compact, non-contacting copper coil is new. Application scenarios for compact transducer techniques include very narrow and hostile environments, in which, e.g., quickly moving metal parts must be tested with only one, non-contacting ultrasound shot. The small transducer coil can be operated remotely with a cable connection, separate from the much bulkier supply circuitry. Several options for more technical and fundamental progress are discussed. Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1393-opus4-1285 VL - 17 IS - 926 ER - TY - THES A1 - Weidenmüller, Jens T1 - Optimization of Encircling Eddy Current Sensors for Online Monitoring of Hot Rolled Round Steel Bars N2 - Modern manufacturing industries are continually working on quality enhancements for the hot rolling process of round products. One method for improving the finalisation of the rods is the implementation of an automatic size control system. As a result of these trends over the last few years, there has been an increasing demand for more accurate online measurements. Thus the reason for the research performed for this thesis. A particular challenge throughout this research was dealing with the temperature changes (up to 1200°C) from the in- and output of the fervent rolling stocks, and the effect this temperature changes had on the sensors. Furthermore, there is also high demand for developing fast and practical electronic measuring equipment, capable of measuring during high transport velocities (up to 120 m/s). The eddy current principle is just one of the very few methods available which can with-stand such harsh industrial environments. In fact, eddy current sensors are already being integrated into online monitoring tasks for hot rolling processes. The measurement uncertainty, however, is still considerably large for process control purposes. One reason for this lies within the ability for eddy current detectors to receive signals influenced by outward forces, i.e. forces dependent on its location, its geometry, the outside temperature and the material properties of a particular target. Thus the current accuracy for a cross-sectional area measurement, for example, is no higher than 1%. As a result, this thesis investigates the magnitude of all individual influential factors on the eddy current detectors, using model-based analysis techniques. The analytical model provides a solution for all rotationally symmetrical targets and the FEA model covers all of the other influencing parameters in a more time consuming manner. This thesis then provides different methods which are developed to separate the cross-sectional area measurement of a rod from all of the other influencing parameters. In addition, a material tracking approach for round products is developed. Two different kinds of prototypes, capable of measuring approximately 466 Tons of red-hot steel rods during the production process, are finally introduced in this thesis. The usefulness of the eddy current principle is validated by the provided field test results. The count accuracy for the identification of 2876 bars was found to be 99.93%, and the average measurement accuracy for the cross-sectional area experiments was reduced to ± 0.29 % when including all of the findings. KW - Rundstahl KW - Warmwalzen KW - Halberzeugnis KW - Hochtemperatur KW - Inprozesskontrolle Y1 - 2014 SN - 978-3844027945 PB - Shaker CY - Aachen ER - TY - JOUR A1 - Klein, Martin A1 - Rüter, Dirk T1 - A Large and Quick Induction Field Scanner for Examining the Interior of Extended Objects or Humans JF - Progress In Electromagnetics Research B N2 - This study describes the techniques and signal properties of a large, powerful, and linear-scanning 1.5 MHz induction field scanner. The mechanical system is capable of quickly reading the volume of relative large objects, e.g., a test person. The general approach mirrors Magnetic Induction Tomography (MIT), but the details differ considerably from currently-described MIT systems: the setup is asymmetrical, and it operates in gradiometric modalities, either with coaxial excitation with destructive interference or with a single excitation loop and tilted receivers. Following this approach, the primary signals were almost completely nulled, and test objects' real or imaginary imprint was obtained directly. The coaxial gradiometer appeared advantageous: exposure to strong fields was reduced due to destructive interference. Meanwhile, the signals included enhanced components at higher spatial frequencies, thereby obtaining a gradually improved capability for localization. For robust signals, the excitation field can be powered towards the rated limits of human exposure to time-varying magnetic fields. Repeated measurements assessed the important signal integrity, which is affected by the scanner´s imperfections, particularly any motions or respiratory changes in living beings during or between repeated scans. The currently achieved and overall figure of merit for artifacts was 58 dB for inanimate test objects and 44 dB for a test person. Both numbers should be understood as worst case levels: a repeated scan with intermediate breathing and drift/dislocations requires 50 seconds, whereas a single measurement (with respiratory arrest) takes only about 5 seconds. Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1393-opus4-1245 VL - 2017 IS - 78 SP - 155 EP - 173 ER - TY - CHAP A1 - Ahmad, Rabie A1 - Uwe, Handmann T1 - Fusion of Audio- and Visual Cues for Real-Life Emotional Human Robot Interaction T2 - Pattern Recognition N2 - Recognition of emotions from multimodal cues is of basic interest for the design of many adaptive interfaces in human-machine interaction (HMI) in general and human-robot interaction (HRI) in particular. It provides a means to incorporate non-verbal feedback in the course of interaction. Humans express their emotional and affective state rather unconsciously exploiting their different natural communication modalities such as body language, facial expression and prosodic intonation. In order to achieve applicability in realistic HRI settings, we develop person-independent affective models. In this paper, we present a study on multimodal recognition of emotions from such auditive and visual cues for interaction interfaces. We recognize six classes of basic emotions plus the neutral one of talking persons. The focus hereby lies on the simultaneous online visual and accoustic analysis of speaking faces. A probabilistic decision level fusion scheme based on Bayesian networks is applied to draw benefit of the complementary information from both – the acoustic and the visual – cues. We compare the performance of our state of the art recognition systems for separate modalities to the improved results after applying our fusion scheme on both DaFEx database and a real-life data that captured directly from robot. We furthermore discuss the results with regard to the theoretical background and future applications. Y1 - 2019 SN - 978-3-642-23123-0 SP - 346 EP - 355 PB - Springer ER - TY - CHAP A1 - Matthias, Tuma A1 - Ioannis, Iossifidis A1 - Gregot, Schoner T1 - Temporal stabilization of discrete movement in variable environments: An attractor dynamics approach T2 - Proceedings 2009 IEEE International Conference on Robotics and Automation N2 - The ability to generate discrete movement with distinct and stable time courses is important for interaction scenarios both between different robots and with human partners, for catching and interception tasks, and for timed action sequences. In dynamic environments, where trajectories are evolving online, this is not a trivial task. The dynamical systems approach to robotics provides a framework for robust incorporation of fluctuating sensor information, but control of movement time is usually restricted to rhythmic motion and realized through stable limit cycles. The present work uses a Hopf oscillator to produce discrete motion and formulates an online adaptation rule to stabilize total movement time against a wide range of disturbances. This is integrated into a dynamical systems framework for the sequencing of movement phases and for directional navigation, using 2D-planar motion as an example. The approach is demonstrated on a Khepera mobile unit in order to show its reliability even when depending on low-level sensor information. Y1 - 2019 UR - https://ieeexplore.ieee.org/document/5152562/figures#figures U6 - http://dx.doi.org/10.1109/ROBOT.2009.5152562 SP - 683 EP - 686 ER - TY - CHAP A1 - W., Von Seelen A1 - J., Gayko A1 - Uwe, Handmann A1 - T., Kalinke T1 - Scene analysis and organization of behavior in driver assistance systems T2 - Proceedings 2000 International Conference on Image Processing (Cat. No.00CH37101) N2 - To reduce the number of traffic accidents and to increase the drivers comfort, the thought of designing driver assistance systems arose in the past years. Fully or partly autonomously guided vehicles, particularly for road traffic, pose high demands on the development of reliable algorithms. Principal problems are caused by having a moving observer in predominantly natural environments. At the Institut fur Neuroinformatik methods for analyzing driving relevant scenes by computer vision are developed in cooperation with several partners from the automobile industry. We present a solution for a driver assistance system. We concentrate on the aspects of video-based scene analysis and organization of behavior. Y1 - 2019 UR - https://ieeexplore.ieee.org/document/899483 U6 - http://dx.doi.org/10.1109/ICIP.2000.899483 ER - TY - RPRT A1 - Däuper, Olaf A1 - Fouquet, Dörte A1 - Irrek, Wolfgang T1 - Finanzielle Vorsorge im Kernenergiebereich - Etwaige Risiken des Status quo und mögliche Reformoptionen N2 - Gutachten - Finanzielle Vorsorge im Kernenergiebereich - Etwaige Risiken des Status quo und mögliche Reformoptionen im Auftrag des BMWI Bundesministerium für Wirtschaft und Energie, Scharnhorststraße 34-37, 10115 Berlin Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1393-opus4-1105 ER - TY - RPRT A1 - Seefeldt, Friedrich A1 - Offermann, Ruth A1 - Duscha, Markus A1 - Brischke, Lars-Arvid A1 - Schmitt, Corinna A1 - Irrek, Wolfgang A1 - Ansari, Esmail A1 - Meyer, Christian T1 - Marktanalyse und Marktbewertung sowie Erstellung eines Konzeptes zur Marktbeobachtung für ausgewählte Dienstleistungen im Bereich Energieeffizienz N2 - Endbericht (überarbeitete Fassung) Marktanalyse und Marktbewertung sowie Erstellung eines Konzeptes zur Marktbeobachtung für ausgewählte Dienstleistungen im Bereich Energieeffizienz Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1393-opus4-1090 ER -