Wave Component Analysis of Fluid-Loaded, Finite Cylindrical Shell Response

1995 ◽  
Author(s):  
Karl Grosh ◽  
Peter M. Pinsky
Keyword(s):  
Surface Displacement ◽  
Dispersion Relations ◽  
Wave Number ◽  
Far Field ◽  
Signal Processing Algorithm ◽  
Field Response ◽  
Finite Cylindrical Shell ◽  
Finite Shell ◽  
Complex Dispersion

Abstract In this paper, the surface displacement response of a finite fluid-loaded shell and the resulting far field acoustic pressure are studied. A high resolution signal processing algorithm is applied to the surface displacement to estimate the constituent wave numbers and corresponding amplitudes for these wave components. This parameter estimation technique identifies the fluid-loaded cylinder’s complex dispersion relations from finite shell data; the dispersion relations consist of subsonic, leaky, evanescent and oscillatory-decaying wave-number loci. The identified results are compared to the analytic dispersion relations. The far field pressure radiated due to each wave-number component is computed allowing for the determination of important contributors to the far field response. For the frequencies studied, the subsonic wave dominates the far field response due to the finite length of the shell and large amplitude of this component. The supersonic components have the next largest contribution to the far field pressure.

Collisionless damping of plasma waves as a real physical phenomenon does not exist

2014 ◽  
Vol 6 (3) ◽  
pp. 1291-1296
Author(s):  
V. N. Soshnikov
Keyword(s):  
Energy Conservation ◽  
Dispersion Equation ◽  
Physical Phenomenon ◽  
Harmonic Wave ◽  
Collisionless Plasma ◽  
Plasma Waves ◽  
Wave Number ◽  
Erroneous Statement ◽  
Complex Dispersion

Trivial logic of collisionless plasma waves is reduced to using complex exponentially damping/growing wave functions to obtain a complex dispersion equation for their wave number 1 k and the decrement/increment 2 k (for a given real frequency  and complex wave number k  k1  ik2 ), whose solutions are ghosts 1 2 k , k which do not have anything to do at 2 k  0 with the real solution of the dispersion equation for the initial exponentially damping/growing real plasma waves with the physically observable quantities 1 2 k , k , for which finding should be added, in this case, the second equation of the energy conservation law. Using a complex dispersion equation for the simultaneous determination of 1 k and 2 k violates the law of energy conservation, leads to a number of contradictions, is logical error, and finally also the mathematical error leading to both erroneous statement on the possible existence of exponentially damping/growing harmonic wave solutions and to erroneous values 1 k and 2 k . Mathematically correct conclusion about the damping/growing of virtual complex waves of collisionless plasma is wrongly attributed to the actual real plasma waves.

Determination of the energy wave-number characteristic of Pb from experimental phonon frequencies

1969 ◽  
Vol 62 (2) ◽  
pp. 379-389 ◽  
Author(s):  
V. Bortolani ◽  
P. Ottaviani
Keyword(s):  
Wave Number

Determination of geometric properties of SNOM tips by means of combined far-field and near-field evaluation

1999 ◽  
Author(s):  
Soenke Seebacher ◽  
Wolfgang Osten ◽  
Werner P. O. Jueptner ◽  
Vadim P. Veiko ◽  
Nikolay B. Voznesensky
Keyword(s):  
Near Field ◽  
Field Evaluation ◽  
Far Field ◽  
Geometric Properties

Determination of Underwater Plate Dynamics Using Laser Beams

1974 ◽  
Vol 96 (3) ◽  
pp. 722-728
Author(s):  
Rudolph E. Croteau ◽  
Herman E. Sheets
Keyword(s):  
Near Field ◽  
Surface Displacement ◽  
Coupled System ◽  
Green Laser ◽  
Testing Facility ◽  
Acoustic Testing ◽  
Propeller Blades ◽  
The Relationship ◽  
Made In

Underwater plate vibration and its associated noise are of interest for the analysis of ship structures, propeller blades, and other areas of underwater acoustics. In order to analyze the relationship between a plate vibrating underwater and the acoustic pressure in the near-field, optical interferometric holography, using a blue-green laser beam, was used to determine surface displacement for the vibrating plate, which was excited through a fluid-coupled system. Acoustic measurements of the same source were made in a water tower concurrently with the holography and later at a precision acoustic testing facility. This method permits prediction of underwater plate modal frequencies and shapes with high accuracy.

Micro Roughness Determination Of Periodic Microelectronics Structures Using Optical Far Field Measurements

2011 ◽  
Author(s):  
Alexandre Vauselle ◽  
Philippe Maillot ◽  
Gaëlle Georges ◽  
Carole Deumié ◽  
David G. Seiler ◽  
...  
Keyword(s):  
Field Measurements ◽  
Far Field
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