TY - CHAP A1 - Konetzke, Eric A1 - Rutsch, Matthias A1 - Hoffmann, Maik A1 - Unger, Alexander A1 - Golinske, René A1 - Killat, Dirk A1 - Ramadas, Sivaram Nishal A1 - Dixon, Steve A1 - Kupnik, Mario T1 - Phased array transducer for emitting 40-kHz air-coupled ultrasound without grating lobes T2 - Proceedings, IEEE International Ultrasonics Symposium (IUS), 21 Oct - 24 Oct 2015 Y1 - 2015 U6 - https://doi.org/10.1109/ULTSYM.2015.0019 PB - IEEE ER - TY - CHAP A1 - Hoffmann, Maik A1 - Unger, Alexander A1 - Jäger, Axel A1 - Kupnik, Mario T1 - Effect of transducer port cavities in invasive ultrasonic transit-time gas flowmeters T2 - IEEE International Ultrasonics Symposium, Taipeh (Taiwan), 2015 Y1 - 2015 U6 - https://doi.org/10.1109/ULTSYM.2015.0272 SP - 1 EP - 4 PB - IEEE ER - TY - THES A1 - Hoffmann, Maik T1 - Untersuchung zur Realisierbarkeit eines Ultraschalldurchflussmessgerätes mittels schmalbandiger Ultraschallwandler N2 - Schmalbandige Ultraschallwandler versprechen durch ihre Anpassung an Gase deutlich höhere Schalldrücke und eine bessere Sensitivität und somit für den Einsatz in Gasultraschalldurchflussmesssystemen einen alternativen Ansatz. Insbesondere die, für die Verwendung in Gasen neuen, Capacitive Micromachined Ultrasonic Transducers (CMUTs) bieten sich an, da sie auch in rauen Umweltbedingungen eingesetzt werden können. Damit bieten sie einen neuen Ansatz zur Verwendung in Ultraschalldurchflussmessgeräten für Gase. Bisher wird beim Einsatz von Ultraschallwandlern mit breitbandigen Typen gearbeitet und mittels Impulsen und Korrelation die Laufzeit bestimmt. Diese Verfahren sind nicht für schmalbandige Wandler geeignet. Zur optimalen Umsetzung der Analyse wird eine Bestimmung der Richtcharakteristik der Ultraschallwandler, der Schallausbreitung im Flowmeter und möglicher Störgeräusche durchgeführt. Aus diesen Ergebnissen wird unter anderem ein mehrkanaliges Durchflussmessgerät aufgebaut, welches eine optimale Schallausbreitung ohne eine Beeinflussung der Strömung ermöglicht und nur einen Ultraschallsender benötigt. Anhand von Simulationen und Messungen an zwei aufgebauten Durchflussmessern werden im Rahmen dieser Arbeit verschiedene Verfahren untersucht, die es ermöglichen, bei extrem schmalbandigen Wandlern die Laufzeit zu bestimmen. Es kristallisieren sich zwei Continuous Wave (CW)-Verfahren heraus, die einen Einsatz dieser Wandler ermöglichen. Die Phasenbestimmung mittels 6-Tor-Methode sowie ein in einem Field Programmable Gate Array (FPGA) umgesetztes Zählverfahren liefert kontinuierlich die Phasenverschiebung bzw. Laufzeit der Signale, aus der die Strömungsgeschwindigkeit bestimmt werden kann. Im Vergleich zu einem Strömungsmesser mit einer Prandtlsonde zeigen beide Verfahren qualitative ebenbürtige Ergebnisse bei signifikant höherer Effizienz. N2 - Narrowband ultrasonic transducer promise a higher acoustic pressure and sensitivity due the better acoustic match to gaseous fluids. Therefore, it is an approach to use them in an ultrasonic gas flow meter (UFM), especially capacitive micromachined ultrasonic transducers (CMUTs) for use in a harsh environment. So far, in UFMs broadband ultrasonic transducer in combination with a Time-of-Flight (ToF) detection based on correlation techniques are used. This approach is not possible for narrowband systems. As first steps in this work the transmitter directivity and sound pressure level of the used ultrasonic transducer are measured. The acoustic boundary conditions in the UFM and noise produced by the flow are also a concern of this research and are investigated. Out of these results a single transmitter UFM with three channels was built in addition to the classic one. This type uses an optimal sound beam without disturbing the gas flow. Several methods based on continuous wave techniques were investigated. In the performed simulations and measurements two principles show better results. The measure of the phase shift with the 6-port-method and a counting algorithm in a Field Programmable Gate Array (FPGA) provide the time of flight needed for calculating the flow speed. Compared to a flow meter based on a Pitot tube the results of these methods are of a competing validity. Y1 - 2019 CY - Cottbus ER - TY - CHAP A1 - Unger, Alexander A1 - Konetzke, Eric A1 - Rutsch, Matthias A1 - Hoffmann, Maik A1 - Ramadas, Sivaram Nishal A1 - Dixon, Steve A1 - Kupnik, Mario T1 - Versatile air-coupled phased array transducer for sensor applications T2 - IEEE Sensors 2015, Busan, South Korea Y1 - 2015 U6 - https://doi.org/10.1109/ICSENS.2015.7370187 SP - 1 EP - 4 PB - IEEE ER - TY - CHAP A1 - Ho, Min-Chieh A1 - Hoffmann, Maik A1 - Unger, Alexander A1 - Park, Kwan Kyu A1 - Kupnik, Mario A1 - Khuri-Yakub, Butrus T. T1 - CMUTs in Permanent Contact Operation for High Output Pressure T2 - Proceedings, ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems and ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels Y1 - 2015 SN - 978-0-7918-5690-1 U6 - https://doi.org/10.1115/IPACK2015-48733 PB - ASME CY - New York, NY ER - TY - CHAP A1 - Guseva, Anastasia A1 - Hoffmann, Maik A1 - Unger, Alexander A1 - Zulk, Silvia A1 - El Amien, Mohamed Balla A1 - Sarradj, Ennes A1 - Kupnik, Mario T1 - Ultrasonic transducer characterization in air based on an indirect acoustic radiation pressure measurement T2 - IEEE International Ultrasonics Symposium (IUS), 21–24 October 2015, Taipei, Taiwan Y1 - 2015 U6 - https://doi.org/10.1109/ULTSYM.2015.0333 SP - 1 EP - 4 PB - IEEE ER - TY - CHAP A1 - Golinske, René A1 - Hoffmann, Maik A1 - Konetzke, Eric A1 - Unger, Alexander A1 - Rutsch, Matthias A1 - Kupnik, Mario T1 - Diffraction loss calculation based on boundary element method for an air-coupled phased array T2 - Proceedings IEEE International Ultrasonics Symposium Proceedings, 2015 Y1 - 2015 U6 - https://doi.org/10.1109/ULTSYM.2015.0375 PB - IEEE ER - TY - CHAP A1 - Unger, Alexander A1 - Hoffmann, Maik A1 - Ho, Min-Chieh A1 - Park, Kwan Kyu A1 - Khuri-Yakub, Butrus T. A1 - Kupnik, Mario T1 - Finite element analysis of mechanically amplified CMUTs T2 - Proceedings, 2013 IEEE International Ultrasonics Symposium N2 - We introduce the possibility of improving a single-cell capacitive micromachined ultrasonic transducer (CMUT) for air-coupled ultrasound by simply adding a hollow conical-shaped structure (horn) on top of the CMUT plate. The main objective is to improve both transmit and receive sensitivity by lowering the center-to-average displacement ratio, which for bending plate operated devices inherently is limited. In addition, for receive mode the force generated from the impinging sound pressure wave is concentrated to the center of the plate, resulting in larger signals and, in contrast to piston-shaped plates, the horn has the advantage of only moderately increasing the modal mass of the structure. By using finite element analysis and first sound pressure measurements of our modified CMUT, we demonstrate that this idea is feasible and promising for air-coupled CMUTs operating at frequencies below 150kHz, as it has been been proven to be successful for commercially available piezoelectric - driven bending plate devices as well. Y1 - 2013 U6 - https://doi.org/10.1109/ULTSYM.2013.0074 SP - 287 EP - 290 PB - IEEE ER - TY - CHAP A1 - Hoffmann, Maik A1 - Unger, Alexander A1 - Ho, Min-Chieh A1 - Park, Kwan Kyu A1 - Khuri-Yakub, Butrus T. A1 - Kupnik, Mario T1 - Volumetric characterization of ultrasonic transducers for gas flow metering T2 - Proceedings, 2013 IEEE International Ultrasonics Symposium N2 - The design of ultrasonic gas flowmeters requires a thorough three dimensional characterization of the acoustic sound field. For large pipe flowmeters, such as used for flare gas metering, the transducers are operated at frequencies ranging from 20 kHz up to 150 kHz. Thus, in this work we use a commercially available calibrated 1/8-inch microphone, mounted on a 3D positioning system for performing volumetric measurements in a volume of up to 1x1x1 m. By using proper corrections in terms of angular and free-field response of the microphone, the measurement system is efficient and delivers around 30000 measurements in about only eight hours. The data then is visualized in form of 3D figures or various slices to extract all relevant information. The system has been used to identify non-uniform velocity profiles in capacitive micromachined ultrasonic transducers (CMUTs), operating in permanent contact mode. Further, the system can be used to investigate the effect of various acoustic boundary conditions the transducers are facing when mounted inside transducer port cavities and it can be used for general model validation purpose. Y1 - 2013 U6 - https://doi.org/10.1109/ULTSYM.2013.0336 SP - 1315 EP - 1318 PB - IEEE ER - TY - CHAP A1 - Rutsch, Matthias A1 - Konetzke, Eric A1 - Unger, Alexander A1 - Hoffmann, Maik A1 - Ramadas, Sivaram Nishal A1 - Dixon, Steve A1 - Kupnik, Mario T1 - Extending the receive performance of phased ultrasonic transducer arrays in air down to 40 kHz and below T2 - IEEE International Ultrasonics Symposium, Taipeh (Taiwan), 2015 Y1 - 2015 U6 - https://doi.org/10.1109/ULTSYM.2015.0095 SP - 1 EP - 4 PB - IEEE ER -