scholarly journals SEISMIC MODEL STUDY OF REFRACTIONS FROM A LAYER OF FINITE THICKNESS

Geophysics ◽  
1954 ◽  
Vol 19 (3) ◽  
pp. 388-401 ◽  
Author(s):  
Frank Press ◽  
Jack Oliver ◽  
Maurice Ewing
Keyword(s):  
Travel Time ◽  
Layer Thickness ◽  
Finite Thickness ◽  
Selective Absorption ◽  
Two Dimensional ◽  
Seismic Model ◽  
Dimensional Model ◽  
Model Experiments ◽  
Model Study ◽  
Two Dimensional Model

Two dimensional model experiments on refractions from layers of finite thickness are described. Refractions can be unreliable for velocity and depth determinations when they occur with wavelengths which are large compared to the layer thickness. Discrepancies reported between refraction velocities and borehole velocities can be partially accounted for in this manner. Even simple two‐ and three‐layer models can show such effects as misleading second arrivals, echeloning of travel time curves, masked layers, and selective absorption in the overburden.

Model study of explosion-generated Rayleigh waves in a half space

1964 ◽  
Vol 54 (2) ◽  
pp. 475-484
Author(s):  
I. N. Gupta ◽  
C. Kisslinger
Keyword(s):  
Rayleigh Wave ◽  
Half Space ◽  
Rayleigh Waves ◽  
Radial Component ◽  
Two Dimensional ◽  
Source Depth ◽  
Dimensional Model ◽  
Retrograde Motion ◽  
Model Study ◽  
Two Dimensional Model

ABSTRACT The Rayleigh waves generated by an explosion on or in the interior of a two-dimensional model show that the source acts as a downward impulse when the shot is on or just below the surface, and as a buried source of compression for deeper shots. The seismograms are in agreement with established theory for the line source on or in a half-space. The source depth corresponding to the reversal of polarity of the Rayleigh wave is small, and appears to be equal to the radius of the zone of inelastic failure around the shot. The polarity reversal is a true indication of a change in the mechanism of Rayleigh wave generation, and is not related to the change from retrograde motion at the free surface to prograde motion in the interior associated with the change in sign of the radial component at depth.

Thermal structure of the Venus ionosphere: A two-dimensional model study

1986 ◽  
Vol 13 (1) ◽  
pp. 10-13 ◽  
Author(s):  
R. C. Whitten ◽  
R. P. Singhal ◽  
W. C. Knudsen
Keyword(s):  
Thermal Structure ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Model Study ◽  
Two Dimensional Model

scholarly journals Frictionally Excited Thermoelastic Instability in Multi-Disk Clutches and Brakes

2000 ◽  
Vol 123 (4) ◽  
pp. 865-871 ◽  
Author(s):  
P. Decuzzi ◽  
M. Ciaverella ◽  
G. Monno
Keyword(s):  
Critical Speed ◽  
Finite Thickness ◽  
Thickness Ratio ◽  
Wave Parameter ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Thermoelastic Instability ◽  
Dimensional Plane ◽  
Two Dimensional Model ◽  
Radial Thickness

The propensity toward thermoelastic instability (TEI) in multi-disk clutches and brakes is investigated by introducing a new bidimensional analytical model, where metal and friction disks are replaced by two-dimensional layers of finite thickness. This new model permits to estimate the effect of the thickness ratio a1/a2, between friction and metal disks, on the critical speed, critical wave parameter and migration speed of the sliding system. It is found that as the thickness ratio a1/a2 decreases the critical speed reduces significantly taking up values about 80 percent smaller than that predicted by previous two-dimensional models for commonly used ratios 0.1<a1/a2<1, whilst the critical wave parameter slightly increases. Therefore, not only the susceptibility towards TEI can be reduced by changing the material properties of the friction lining but also by adjusting suitably the thickness ratio of the disks. The two-dimensional model is also employed to determine the critical speed in a real multi-disk clutch, and the results are compared with a three-dimensional finite element code. It is shown that the critical speed estimated by the present two-dimensional plane strain model is in good agreement with that determined by the FE code for sufficiently large radial thickness of the disks, whilst the two-dimensional plane stress solution has to be used for relatively small radial thickness ratios. Also, it is found that the critical number of hot spots is independent of the radial thickness ratio and it is correctly predicted by the two-dimensional model.

Implications of smaller concentrations of stratospheric OH: A two-dimensional model study of ozone perturbations

1981 ◽  
Vol 15 (9) ◽  
pp. 1583-1589 ◽  
Author(s):  
R.C. Whitten ◽  
W.J. Borucki ◽  
H.T. Woodward ◽  
L.A. Capone ◽  
C.A. Riegel ◽  
...  
Keyword(s):  
Two Dimensional ◽  
Dimensional Model ◽  
Model Study ◽  
Two Dimensional Model

Revised predictions of the effect on stratospheric ozone of increasing atmospheric N2O and chlorofluoromethanes: A two-dimensional model study

1983 ◽  
Vol 17 (10) ◽  
pp. 1995-2000 ◽  
Author(s):  
R.C Whitten ◽  
W.J Borucki ◽  
H.T Woodward ◽  
L.A Capone ◽  
C.A Riegel✠
Keyword(s):  
Stratospheric Ozone ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Model Study ◽  
Two Dimensional Model

Thermomechanical Behavior of Multilayered Media: Results

1990 ◽  
Vol 112 (2) ◽  
pp. 317-323 ◽  
Author(s):  
J. M. Leroy ◽  
A. Floquet ◽  
B. Villechaise
Keyword(s):  
Layered Medium ◽  
Finite Thickness ◽  
Thermomechanical Behavior ◽  
Stress Fields ◽  
Two Dimensional ◽  
Variable Properties ◽  
Dimensional Model ◽  
Multilayered Media ◽  
Thin Coatings ◽  
Two Dimensional Model

To study the thermoelastic behavior of coatings a two-dimensional model of a finite thickness layered medium submitted to a moving heat flux was presented in a previous paper (Leroy, Floquet, and Villechaise, 1989). The influence of thin coatings with variable properties or thicknesses on the temperature and stress fields is studied here. These results show that important stresses occur in a coating whose properties differ from those of the substrate, even for low temperature rises.

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