Ray Theory. Media of Variable Velocity

2018 ◽  
pp. 183-208
Keyword(s):  
Variable Velocity ◽  
Ray Theory

scholarly journals An Electrostatic Self-Excited Resonator with Pre-Tension/Pre-Compression Constraint for Active Rotation Control

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 650
Author(s):  
Ruide Yun ◽  
Yangsheng Zhu ◽  
Zhiwei Liu ◽  
Jianmei Huang ◽  
Xiaojun Yan ◽  
...  
Keyword(s):  
Maximum Velocity ◽  
Flapping Wings ◽  
Variable Velocity ◽  
Beam Length ◽  
Dc Voltage ◽  
Middle Position ◽  
Simply Supported ◽  
Maximum Value ◽  
Constraint Structure

We report a novel electrostatic self-excited resonator driven by DC voltage that achieves variable velocity-position characteristics via applying the pre-tension/pre-compression constraint. The resonator consists of a simply supported micro-beam, two plate electrodes, and two adjustable constraint bases, and it can be under pre-compression or pre-tension constraint by adjusting the distance L between two constraint bases (when beam length l > L, the resonator is under pre-compression and when l < L, it is under pre-tension). The oscillating velocity of the beam reaches the maximum value in the position around electrodes under the pre-compression constraint and reaches the maximum value in the middle position between two electrodes under the pre-tension condition. By changing the constraint of the microbeam, the position of the maximum velocity output of the oscillating beam can be controlled. The electrostatic self-excited resonator with a simple constraint structure under DC voltage has great potential in the field of propulsion of micro-robots, such as active rotation control of flapping wings.

Tomographic inversion of measured cross-correlation functions of ocean noise in shallow water using ray theory

2016 ◽  
Vol 62 (4) ◽  
pp. 436-446 ◽  
Author(s):  
V. V. Goncharov ◽  
A. S. Shurup ◽  
O. A. Godin ◽  
N. A. Zabotin ◽  
A. I. Vedenev ◽  
...  
Keyword(s):  
Shallow Water ◽  
Correlation Functions ◽  
Cross Correlation ◽  
Ray Theory ◽  
Tomographic Inversion ◽  
Ocean Noise

Time-Domain Analysis of SOFAR Propagation in Low-Latitude Sea Area by Wave Theory and Ray Theory

1995 ◽  
Vol 34 (Part 1, No. 5B) ◽  
pp. 2940-2942
Author(s):  
Shinichi Imayoshi ◽  
Toshio Tsuchiya ◽  
Toshiaki Kikuchi ◽  
Akio Hasegawa
Keyword(s):  
Time Domain ◽  
Wave Theory ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Ray Theory ◽  
Low Latitude ◽  
Sea Area

Wave action on currents with vorticity

1999 ◽  
Vol 386 ◽  
pp. 329-344 ◽  
Author(s):  
BENJAMIN S. WHITE
Keyword(s):  
Phase Shift ◽  
Deep Water ◽  
Current Velocity ◽  
Wave Action ◽  
Ray Theory ◽  
Wkb Method ◽  
Interaction Of Waves ◽  
New Equation ◽  
Spatially Varying

The interaction of waves on deep water with spatially varying currents may be described by a ray theory, with the wave amplitudes determined by the principle of conservation of wave action (CWA). However, all previous deep water derivations of CWA are restricted to the case of an irrotational current. In this paper, both the ray theory and CWA are derived by a WKB method without the assumption of irrotationality. Also derived is a new equation for a spatially varying phase shift which is not predicted by the usual ray theory, and which, in general, displaces the positions of the wave crests by a distance on the order of a wavelength. This phase shift, which is caused by variations of the current velocity with depth, vanishes in the irrotational case, and so is in accord with the irrotational theory.

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