Focusing of a sound beam in an underwater waveguide using a vertical antenna

2013 ◽  
Vol 59 (3) ◽  
pp. 297-304 ◽  
Author(s):  
V. V. Artel’nyi ◽  
P. V. Artel’nyi ◽  
A. L. Virovlyansky ◽  
P. I. Korotin ◽  
A. V. Nasedkin ◽  
...  
Keyword(s):  
Author(s):  
Shaojun Wang ◽  
Xiaoying Tang ◽  
Houde Yu ◽  
Yaozhou Qian ◽  
Jun Cheng ◽  
...  

Responding to complexity and particularity welding on the geometry of TKY tubular node, this paper constructs mathematical model of tubular joint weld of arbitrary section by simplifying the geometry structure, and draws welded joints and ultrasonic sound beam lines based on the actual specifications in order to solve the problems of low efficiency, positioning difficulty, missing inspection and etc. The computeraided simulation technology can realize the visualization in the beam coverage model of welded joints, which can commendably guide the design of ultrasonic phased array inspection and overcome the blindness of the instrument detection parameters, thus improving the effectiveness and pertinence of the actual detection. Study shows that it is beneficial to enhance the effectiveness of the detection tubular joint weld by employment of Visual beam and ultrasonic phased array technology.


2016 ◽  
Vol 30 (08) ◽  
pp. 1650096 ◽  
Author(s):  
Shuzeng Zhang ◽  
Xiongbing Li ◽  
Hyunjo Jeong

A more general two-dimensional wave motion equation with consideration of attenuation and nonlinearity is proposed to describe propagating nonlinear Rayleigh waves of finite amplitude. Based on the quasilinear theory, the numerical solutions for the sound beams of fundamental and second harmonic waves are constructed with Green’s function method. Compared with solutions from the parabolic approximate equation, results from the general equation have more accuracy in both the near distance of the propagation direction and the far distance of the transverse direction, as quasiplane waves are used and non-paraxial Green’s functions are obtained. It is more effective to obtain the nonlinear Rayleigh sound beam distributions accurately with the proposed general equation and solutions. Brief consideration is given to the measurement of nonlinear parameter using nonlinear Rayleigh waves.


Tempo ◽  
1991 ◽  
pp. 18-23 ◽  
Author(s):  
Stephen Montague

In the early 1920s and 30s a strange electronic instrument found its way from Russia into some of the more fashionable ballrooms, night clubs, and concert halls in Europe and America. This exotic new invention, called the ‘theremin’ or ‘thereminvox’, caused a considerable stir. Part of the interest was its unusual sound (like a musical saw mated with a light soprano), but its most dramatic feature was that the performer never actually touched the instrument. He or she simply waved graceful hands near the two antennae (one set vertically, the other looped horizontally) to coax out seamless, melifluous melodies. The proximity of the right hand to the vertical antenna changed the ultrasonic electromagnetic field, thus changing the pitch over about a six-octave range. The left hand (or sometimes a foot pedal) controlled the volume. By gently shaking the right hand at the antenna a vibrato could be achieved, giving performances a little more musical (not to mention choreographic) interest. Fashionable women dressed in long gowns seemed to be favourite photographic subjects of the period as performers, as well as the inventor himself, poised ‘playing the rods’ in full dress tails, arms outstretched like a great conductor–or perhaps sorcerer.


1977 ◽  
pp. 62-89 ◽  
Author(s):  
Josef Krautkrämer ◽  
Herbert Krautkrämer
Keyword(s):  

2012 ◽  
Vol 588-589 ◽  
pp. 703-706
Author(s):  
Zhi Wei Zhang ◽  
Bo Wang ◽  
Zhi Gang Zhu

In order to improve the SINR of the beam-former in the case of DOA mismatch, the paper raises the probability of constraint beam-forming algorithm based on mutative scale chaos optimization in connection with the worst performance of the best sound beam-forming algorithm. By introducing the probability constraints confidence interval and the signal vector error distribution law in the beam-forming, the constrained optimization problem is eventually turned into a nonlinear optimization problem. Then the global optimal weight is searched by the mutative scale chaos optimization method. Simulations have shown that the algorithm can significantly improve the SINR.


2012 ◽  
Vol 198-199 ◽  
pp. 1047-1052
Author(s):  
Yang Zhang ◽  
Li Min Tao

Audio directional system is a new-style loudspeaker, which can project the sound beam onto a given region as light beam. In this paper, the basic working principle and the system components of audio directional system are proposed. The total harmonic distortion of the self-demodulated signal is analyzed based on “Berktay far-field solution”. Besides, this paper has designed the audio directional experimental system whose performances have been tested. The shortcomings of the self-demodulation theory are pointed out after the comparison between the test data and the theoretical analysis results.


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