AN EXPERIMENT WHICH MEASURES RESONANT MODE CONVERSION IN He II

1978 ◽  
Vol 39 (C6) ◽  
pp. C6-228-C6-229
Author(s):  
S. Garrett ◽  
S. Adams ◽  
S. Putterman ◽  
I. Rudnick
Keyword(s):  
Mode Conversion ◽  
Resonant Mode

Higher Order Corrections to Resonant Mode Conversion

2007 ◽  
Author(s):  
A. S. Richardson ◽  
E. R. Tracy ◽  
A. N. Kaufman ◽  
Philip M. Ryan ◽  
David Rasmussen
Keyword(s):  
Mode Conversion ◽  
Resonant Mode ◽  
Higher Order ◽  
Higher Order Corrections

scholarly journals Periodic Tubular Structures and Phononic Crystals towards High-Q Liquid Ultrasonic Inline Sensors for Pipes

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5982
Author(s):  
Nikolay Mukhin ◽  
Ralf Lucklum
Keyword(s):  
Mode Conversion ◽  
Phononic Crystal ◽  
Resonant Mode ◽  
Phononic Crystals ◽  
Acoustic Energy ◽  
Wave Radiation ◽  
Q Factor ◽  
Tubular Structures ◽  
High Q ◽  
Ultrasound Sensor

The article focuses on a high-resolution ultrasound sensor for real-time monitoring of liquid analytes in cylindrical pipes, tubes, or capillaries. The development of such a sensor faces the challenges of acoustic energy losses, including dissipation at liquid/solid interface and acoustic wave radiation along the pipe. Furthermore, we consider acoustic resonant mode coupling and mode conversion. We show how the concept of phononic crystals can be applied to solve these problems and achieve the maximum theoretically possible Q-factor for resonant ultrasonic sensors. We propose an approach for excitation and measurement of an isolated radial resonant mode with minimal internal losses. The acoustic energy is effectively localized in a narrow probing area due to the introduction of periodically arranged sectioned rings around the tube. We present a sensor design concept, which optimizes the coupling between the tubular resonator and external piezoelectric transducers. We introduce a 2D-phononic crystal in the probing region for this purpose. The Q-factor of the proposed structures show the high prospects for phononic crystal pipe sensors.

Resonant mode conversion of a shear Alfvén wave

1987 ◽  
Vol 65 (4) ◽  
pp. 357-358
Author(s):  
Bhimsen K. Shivamoggi
Keyword(s):  
Solar Wind ◽  
Acoustic Wave ◽  
Wave Energy ◽  
Mode Conversion ◽  
Resonant Absorption ◽  
Resonant Mode ◽  
Alfven Wave ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Kinetic Alfven Wave

A new mechanism for the resonant absorption of a shear Alfvén wave is proposed that involves a direct mode conversion of the latter to an ion-acoustic wave without bringing in the intermediary — the kinetic Alfvén wave. The fraction of the incident Alfvén-wave energy that is mode-converted to an ion-acoustic wave is calculated. This mechanism likely operates in the solar wind, where it might lead to heating of the plasma.

Generation of Internal Tides by Tide-Topography Resonance over Weak Topography: Analytical Calculation

2012 ◽  
Vol 588-589 ◽  
pp. 1964-1971
Author(s):  
Li Dan Wu ◽  
Chun Bao Miao
Keyword(s):  
Conversion Rate ◽  
Mode Conversion ◽  
Bottom Topography ◽  
Analytical Calculation ◽  
Internal Tide ◽  
Resonant Mode ◽  
Internal Tides ◽  
Resonant Modes ◽  
Minimum Amplitude ◽  
Baroclinic Modes

Internal tides generated by the interaction of the barotropic tide with bottom topography are studied by using an analytical solution. Tide-topography resonance takes place when the wavenumber of the truncated sinusoidal topography is equal to that of one baroclinic mode. The minimum amplitude of the resonant mode increases from the center of the domain to both sides of the topography; while the maximum keeps the same. Amplitudes of the internal tides and mode conversion rate are analyzed as a function of the length and wavenumber of the topography. For non-resonant modes, the amplitudes are weak and vary periodically with the extending of the topography, and are exactly zero when the length of topography is integral times of the mode-1 wavelength. For resonant modes, the amplitudes increase with the length of the topography. For each internal tide mode, there is a response zone, where the amplitude for one mode is obviously larger than other baroclinic modes. The response zones for high modes are wider than those for low modes. Mode conversion rate is obviously high when the wavenumber of the topography is equal to that of the baroclinic modes; otherwise it is almost zero. Furthermore, mode conversion rate for small topography wavenumber is more than that for large topography wavenumber with the same number of the sinusoidal topography, and is less with the same topography length.

scholarly journals The Asymmetric Flexure Hinge Structures and the Hybrid Excitation Methods for Piezoelectric Stick-Slip Actuators

2021 ◽  
Author(s):  
Tinghai Cheng ◽  
Xiaosong Zhang ◽  
Xiaohui Lu ◽  
Hengyu Li ◽  
Qi Gao ◽  
...  
Keyword(s):  
High Speed ◽  
Low Voltage ◽  
Mode Conversion ◽  
Resonant Mode ◽  
Superior Performance ◽  
Flexure Hinge ◽  
Asymmetric Structure ◽  
Stick Slip ◽  
Output Performance ◽  
Long Stroke

Piezoelectric stick–slip actuators have become viable candidates for precise positioning and precise metering due to simple structure and long stroke. To improve the performances of the piezoelectric stick–slip actuators, our team deeply studies the actuators from both structural designs and driving methods. In terms of structural designs, the trapezoid-type, asymmetrical flexure hinges and mode conversion piezoelectric stick–slip actuators are proposed to improve the velocity and load based on the asymmetric structure; besides, a piezoelectric stick–slip actuator with a coupled asymmetrical flexure hinge mechanism is also developed to achieve the bidirectional motion. In terms of driving methods, a non-resonant mode smooth driving method (SDM) based on ultrasonic friction reduction is first proposed to restrain the backward motion during the rapid contraction stage. Then, a resonant mode SDM is further developed to improve the output performance of the piezoelectric stick–slip actuator. On this basis, the low voltage and symmetry of the SDM are also discussed. Finally, the direction-guidance hybrid method (DGHM) excitation method is presented to achieve superior performance, especially for high speed.

Sign in / Sign up

Export Citation Format

Share Document