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R. CHANDER 《Geophysical Prospecting》1978,26(3):595-599
The minimum distance criterion of Backus and Gilbert is used to determine the depths of line masses approximating the subsurface two dimensional distribution of density differences responsible for the observed residual Bouguer anomaly values. The quantity minimized is the sum of the squared differences between the starting trial depths and the desired final depths of line masses. The search for the desired depths is limited to preset depth ranges. 相似文献
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A combination of ray theory and diffraction theory has been used to simulate reflections of seismic pulses from a full plane and reflections and diffractions from a half plane buried horizontally in earth models with linear increase of velocity with depth. Wave forms of signals reflected from a full plane in this case are modifications of the source pulse, even if the medium is assumed to be perfectly elastic. The extent of pulse modification increases with increase of the velocity gradient. The duration of the reflected pulse is always longer than that of the source pulse. The pulses diffracted from the edge of the half plane in such cases do not lie along hyperbolic curves in the time-offset plane. Diffracted signals can be observed only up to a limited distance from the edge of the half plane equalling half the horizontal range of the ray which is tangential to the half plane and has its end points at the level of the source and the receiver. 相似文献
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This paper deciphers the late stress systems involved in the development of kink bands in the perspective of thrust regime.
In kink bands, the correlation coefficient for α–β plots is positive near thrusts and negative away from thrusts. The plots show nearly linear relationship near thrusts and
non-linear relationship away from thrusts. The rotation was prominent mechanism of kink band formation near thrusts and rotation
coupled with shearing, along the kink planes away from thrusts. Along thrusts σ
1 is horizontal E–W trend and it rotates to horizontal N–S trend away from the thrust. The proposed model establishes that
(1) the shearing along kink planes led to angular relationship, β < α and (2) the kink planes of conjugate kinks could be used for paleostress analysis even in those cases where shearing along
these planes has occurred. 相似文献
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Long-term climate data records (CDR) are often constructed using observations made by multiple Earth observing sensors over
a broad range of spectra and a large scale in both time and space. These sensors can be of the same or different types operated
on the same or different platforms. They can be developed and built with different technologies and are likely operated over
different time spans. It has been known that the uncertainty of climate models and data records depends not only on the calibration
quality (accuracy and stability) of individual sensors, but also on their calibration consistency across instruments and platforms.
Therefore, sensor calibration inter-comparison and validation have become increasingly demanding and will continue to play
an important role for a better understanding of the science product quality. This paper provides an overview of different
methodologies, which have been successfully applied for sensor calibration inter-comparison. Specific examples using different
sensors, including MODIS, AVHRR, and ETM+, are presented to illustrate the implementation of these methodologies. 相似文献
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R. CHANDER 《Geophysical Prospecting》1977,25(1):120-124
A polygonal ray path connects the seismic source and detector positions when the intervening medium consists solely of constant velocity layers with plane interfaces which may have arbitrary orientation. The coordinates of the ray vertices satisfy a system of coupled equations resulting from the requirement that Fermat's principle be satisfied along the ray path. Solving the system of equations is equivalent to tracing the ray numerically. A notable feature of this approach is that a ray which is critically refracted over a segment of its path requires no special handling. 相似文献
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