Matching theory of ultrasonic transducer at it’s passed inherent resonance zone

Abstract The impedance matching of ultrasonic focusing spherical transducer is one of the primary factors affecting its work efficiency in ultrasonic focusing flow polishing system. To realize the efficient utilization of the vibration energy of the transducer, there are different requirements for the front and rear matching structure of the transducer. That is, the front matching structure should have high transmittance, and the rear matching structure should have high reflectivity. Based on the acoustic impedance matching theory and Kirchhoff's theory, the Influence of the front & back impedance matching structure of spherical focusing ultrasonic transducer to the focus sound pressure is studied theoretically and experimentally. The new matching structure for spherical focusing transducer is proposed based on above research. The experimental result shows that the focus sonic pressure with the new matching structure is increased by 72.03% compared with the traditional structure.

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Nanoparticles Generation using Mono-disperse Droplets by an Ultrasonic Transducer

IEEJ Transactions on Sensors and Micromachines ◽

10.1541/ieejsmas.140.37 ◽

2020 ◽

Vol 140 (2) ◽

pp. 37-42

Author(s):

Nozomu Fujimoto ◽

Takefumi Kanda ◽

Masaya Katsuta ◽

Yusaku Sakata ◽

Yoshiaki Yamada ◽

...

Keyword(s):

Ultrasonic Transducer

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Influence of Ultrasonic Transducer Structural Parameters on the Frictional Plasticizing Heat Generation of Polymer Particles

International Polymer Processing ◽

10.3139/217.3671 ◽

2019 ◽

Vol 34 (4) ◽

pp. 416-424 ◽

Cited By ~ 1

Author(s):

X. Li ◽

H.-G. Tian ◽

W.-W. Zhang ◽

S.-C. Zhang

Keyword(s):

Heat Generation ◽

Structural Parameters ◽

Ultrasonic Transducer ◽

Polymer Particles

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Modeling of a high frequency ultrasonic transducer using periodic structures

10.3728/icultrasonics.2007.vienna.1686_marechal ◽

2007 ◽

Author(s):

P. Maréchal ◽

L. Haumesser ◽

G. Feuillard ◽

L.P. Tran-Huu-Hue ◽

J. Holc ◽

...

Keyword(s):

High Frequency ◽

Periodic Structures ◽

Ultrasonic Transducer

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Design and Experiment of Capacitive Micromachined Ultrasonic Transducer Array for High-Frequency Underwater Imaging

Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) ◽

10.2174/2352096513999201026225123 ◽

2020 ◽

Vol 13 ◽

Author(s):

Yuanyu Yu ◽

Jiujiang Wang ◽

Xin Liu ◽

Sio Hang Pun ◽

Weibao Qiu ◽

...

Keyword(s):

Ultrasound Imaging ◽

High Frequency ◽

Ultrasonic Transducer ◽

Center Frequency ◽

Design Parameters ◽

Underwater Imaging ◽

Release Process ◽

Steel Wires ◽

Capacitive Micromachined Ultrasonic Transducer ◽

Frequency Ultrasound

Background:: Ultrasound is widely used in the applications of underwater imaging. Capacitive micromachined ultrasonic transducer (CMUT) is a promising candidate to the traditional piezoelectric ultrasonic transducer. In underwater ultrasound imaging, better resolutions can be achieved with a higher frequency ultrasound. Therefore, a CMUT array for high-frequency ultrasound imaging is proposed in this work. Methods:: Analytical methods are used to calculate the center frequency in water and the pull-in voltage for determining the operating point of CMUT. Finite element method model was developed to finalize the design parameters. The CMUT array was fabricated with a five-mask sacrificial release process. Results:: The CMUT array owned an immersed center frequency of 2.6 MHz with a 6 dB fractional bandwidth of 123 %. The pull-in voltage of the CMUT array was 85 V. An underwater imaging experiment was carried out with the target of three steel wires. Conclusion:: In this study, we have developed CMUT for high-frequency underwater imaging. The experiment showed that the CMUT can detect the steel wires with the diameter of 100 μm and the axial resolution was 0.582 mm, which is close to one wavelength of ultrasound in 2.6 MHz.

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Reforming the Labour Market in Good and Bad Times

10.1093/oso/9780198821878.003.0005 ◽

2018 ◽

Author(s):

Britta Gehrke ◽

Enzo Weber

Keyword(s):

Time Series ◽

Business Cycle ◽

Labour Market ◽

Markov Switching ◽

Matching Theory ◽

Market Reforms ◽

Structural Reforms ◽

Labour Market Reforms ◽

Short Run ◽

The Business Cycle

This chapter discusses how the effects of structural labour market reforms depend on whether the economy is in expansion or recession. Based on an empirical time series model with Markov switching that draws on search and matching theory, we propose a novel identification of reform outcomes and distinguish the effects of structural reforms that increase the flexibility of the labour market in distinct phases of the business cycle. We find in applications to Germany and Spain that reforms which are implemented in recessions have weaker expansionary effects in the short run. For policymakers, these results emphasize the costs of introducing labour market reforms in recessions.

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