Diffraction of plane sh waves in a half-space

Scattering of antiplane shear waves (SH) in two dimensions by surface and near-surface defects in a homogeneous, isotropic elastic semi-infinite medium has been studied. Attention has been focused here in the range of medium to long wavelengths. A combined finite element and analytical technique has been used to study the problems of scattering by semi-circular and triangular canyons. The results for the former case are compared with the known exact solution and those for the latter case are compared with some available approximate solutions. Finally a problem of multiple scattering by a triangular canyon and a nearby circular tunnel is studied. Numerical results are presented showing the effects of multiple scattering and different angles of incidence. These results are of interest in earthquake engineering.     

Die Vertikaländerung des beschleunigungsfreien Windes in äquatorialen Breiten

Zusammenfassung Wie in mittleren und höheren Breiten bedingt auch am Äquator die meridionale Temperaturverteilung eine Vertikaländerung des reibungs- und beschleunigungsfreien Windes. Allerdings darf man dabei keine Drehung des Windvektors erwarten, da, wie gezeigt wird, sowohl am Äquator als auch in seiner Umgebung ausschliesslich rein zonale stationäre und beschleunigungsfreie Strömungen (bei verschwindenden zonalen Änderungen des Temperatur- und Druckgradienten) in Betracht kommen.

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Summary At the equator vertical variations of a frictionless and unaccelerated wind are caused by the meridional distribution of temperature in a similar way as in higher latitudes. Nevertheless there cannot be expected any deviation of the wind vector with high since only pure zonal winds free of acceleration may be possible around the equator and in its neighbourhood.

     

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