Reflection of high-frequency elastic waves from a non-plane boundary surface of the elastic medium

2007 ◽  
Vol 302 (4-5) ◽  
pp. 925-935 ◽  
Author(s):  
A. Pompei ◽  
M.A. Sumbatyan ◽  
N.V. Boyev
Keyword(s):  
Elastic Medium ◽  
Elastic Waves ◽  
High Frequency ◽  
Boundary Surface ◽  
Plane Boundary

Dynamic properties of reflected and head waves near the critical point

1979 ◽  
Vol 16 (7) ◽  
pp. 1388-1401 ◽  
Author(s):  
Larry W. Marks ◽  
F. Hron
Keyword(s):  
Exact Solution ◽  
High Frequency ◽  
Classical Problem ◽  
Plane Boundary ◽  
Head Wave ◽  
Disk File ◽  
Ray Theory ◽  
Computational Point ◽  
Spherical Waves ◽  
Head Waves

The classical problem of the incidence of spherical waves on a plane boundary has been reformulated from the computational point of view by providing a high frequency approximation to the exact solution applicable to any seismic body wave, regardless of the number of conversions or reflections from the bottoming interface. In our final expressions the ray amplitude of the interference reflected-head wave is cast in terms of a Weber function, the numerical values of which can be conveniently stored on a computer disk file and retrieved via direct access during an actual run. Our formulation also accounts for the increase of energy carried by multiple head waves arising during multiple reflections of the reflected wave from the bottoming interface. In this form our high frequency expression for the ray amplitude of the interference reflected-head wave can represent a complementary technique to asymptotic ray theory in the vicinity of critical regions where the latter cannot be used. Since numerical tests indicate that our method produces results very close to those obtained by the numerical integration of the exact solution, its combination with asymptotic ray theory yields a powerful technique for the speedy computation of synthetic seismograms for plane homogeneous layers.

High‐frequency elastic waves in random composites via the Kramers–Kronig relations

1985 ◽  
Vol 46 (3) ◽  
pp. 243-245 ◽  
Author(s):  
Neima Brauner ◽  
Abraham I. Beltzer
Keyword(s):  
Elastic Waves ◽  
High Frequency ◽  
Random Composites

A Novel Piezoelectric RF-MEMS Resonator with Enhanced Quality Factor

2022 ◽  
Author(s):  
JINCHAO LI ◽  
Zeji Chen ◽  
Wenli Liu ◽  
Jinling Yang ◽  
Yinfang Zhu ◽  
...  
Keyword(s):  
Elastic Waves ◽  
High Frequency ◽  
Rf Mems ◽  
Comprehensive Analysis ◽  
Quality Factors ◽  
Piezoelectric Resonator ◽  
Front End ◽  
Rf Front End ◽  
Mems Resonator ◽  
Compact Size

Abstract This work presents a novel ultra-high frequency (UHF) Lamb mode Aluminum Nitride (AlN) piezoelectric resonator with enhanced quality factors (Q). With slots introduced in the vicinity of the tether support end, the elastic waves leaking from the tether sidewalls can be reflected, which effectively reduces the anchor loss while retaining size compactness and mechanical robustness. Comprehensive analysis was carried out to provide helpful guidance for obtaining optimal slot designs. For various resonators with frequencies ranging from 630 MHz to 1.97 GHz, promising Q enhancements up to 2 times have all been achieved. The 1.97 GHz resonator implemented excellent f × Q product up to 6.72 × 1012 and low motional resistance down to 340 Ω, which is one of the highest performances among the reported devices. The devices with enhanced Q values as well as compact size could have potential application in advanced RF front end transceivers.

ON VOLTERRA'S DISLOCATIONS IN A SEMI-INFINITE ELASTIC MEDIUM

1958 ◽  
Vol 36 (2) ◽  
pp. 192-205 ◽  
Author(s):  
J. A. Steketee
Keyword(s):  
Green’S Function ◽  
Elastic Medium ◽  
Green's Function ◽  
Displacement Field ◽  
General Problem ◽  
Function Method ◽  
Green’S Functions ◽  
Boundary Surface ◽  
Green’S Function Method ◽  
Plane Parallel

In this paper a Green's function method is developed to deal with the problem of a Volterra dislocation in a semi-infinite elastic medium in such a way that the boundary surface of the medium remains free from stresses. (A Volterra dislocation is here defined as a surface across which the displacement components show a discontinuity of the type Δu = U + Ω ×r, where U and Ω are constant vectors.) It is found that the general problem requires the construction of six sets of Green's functions. The method for the construction is outlined and applied to one of the six sets, which is of the type of two double forces with moments in a plane parallel with the boundary. The displacement field thus generated is computed. Several of the results obtained are believed to be of geophysical interest, but a more detailed discussion of these applications is postponed to a further communication which is being prepared.

Diffraction of impulsive elastic waves by a fluid cylinder

1974 ◽  
Vol 75 (3) ◽  
pp. 391-404 ◽  
Author(s):  
Ramanand Jha
Keyword(s):  
Exact Solution ◽  
Circular Cylinder ◽  
Elastic Medium ◽  
Elastic Waves ◽  
Line Source ◽  
Inviscid Fluid ◽  
Geometrical Theory ◽  
Shadow Zone ◽  
Integral Transformations ◽  
Geometrical Theory Of Diffraction

AbstractIn this paper, the problem of diffraction of an impulsive P wave by a fluid circular cylinder has been considered. The cylinder is embedded in an unbounded isotropic homogeneous elastic medium and it is filled with inviscid fluid material. The line source, giving rise to the incident front, is situated outside the cylinder parallel to its axis.The exact solution of the problem is obtained by using the method of dual integral transformations. The solution is evaluated approximately to obtain the motion on the wave front in the shadow zone of the elastic medium. Further, we interpret the approxi mate solutions in terms of Keller's geometrical theory of diffraction. Our result also gives a correction to an earlier investigation of the similar problem by Knopoff and Gilbert(s).

The asymptotic analysis of canonical problems in high-frequency scattering theory

1973 ◽  
Vol 74 (2) ◽  
pp. 289-312
Author(s):  
W. G. C. Boyd
Keyword(s):  
Real Axis ◽  
High Frequency ◽  
Separation Of Variables ◽  
Integral Representations ◽  
Stratified Medium ◽  
Plane Boundary ◽  
The Real ◽  
The Past ◽  
Parameter Separation ◽  
Wave Problems

AbstractThe asymptotic treatment of high-frequency scalar wave problems has in the past been rather unsatisfactory. Typically, the integral representations which arose were evaluated by stationary phase, or as a series of residues. The justification of these methods was usually heuristic and formal. In this paper, a method is advanced which, it is claimed, may be applied to any one-parameter separation of variables problem. The method assumes an integral representation whose contour of integration is the real axis. It is then only necessary to deform this contour in the neighbour-hood of the real axis to derive rigorous asymptotic expansions of the field in both the illumination and shadow. The method is applied to the particular example of scattering by a plane boundary in a general stratified medium with monotonically increasing refractive index.

High-frequency scattering of elastic waves from cylindrical cavities

Wave Motion ◽  
1984 ◽  
Vol 6 (1) ◽  
pp. 41-60 ◽  
Author(s):  
R.J. Brind ◽  
J.D. Achenbach ◽  
J.E. Gubernatis
Keyword(s):  
Elastic Waves ◽  
High Frequency ◽  
Scattering Of Elastic Waves ◽  
Cylindrical Cavities

Asymptotic Expansions of Guided Elastic Waves

1972 ◽  
Vol 39 (2) ◽  
pp. 378-384 ◽  
Author(s):  
B. Rulf ◽  
B. Z. Robinson ◽  
P. Rosenau
Keyword(s):  
Elastic Waves ◽  
High Frequency ◽  
Rayleigh Waves ◽  
Lamb Waves ◽  
Two Dimensions ◽  
Guided Wave ◽  
Curved Surfaces ◽  
Sh Waves ◽  
Free Surfaces ◽  
Wave Problems

The problem of propagation of guided elastic waves near curved surfaces and in layers of nonconstant thickness is investigated. Rigorous solutions for such problems are not available, and a method is shown for the construction of high frequency asymptotic solutions for such problems in two dimensions. The method is applied to Love waves, which are SH-waves in an elastic layer, Rayleigh waves, which are elastic waves guided by a single free surface, and Lamb waves, which are SV-waves guided in a plate or layer with two free surfaces. The procedure shown breaks the second-order boundary-value problems which have to be solved into successions of simpler problems which can be solved numerically. Some numerical examples for Rayleigh waves are carried out in order to demonstrate the utility of our method. The method shown is useful for a large variety of guided wave problems, of which the ones we treat are just examples.

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