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151.
Explicit formula for the geoid-quasigeoid separation 总被引:1,自引:0,他引:1
The explicit formula for the geoid-to-quasigeoid correction is derived in this paper. On comparing the geoidal height and
height anomaly, this correction is found to be a function of the mean value of gravity disturbance along the plumbline within
the topography. To evaluate the mean gravity disturbance, the gravity field of the Earth is decomposed into components generated
by masses within the geoid, topography and atmosphere. Newton’s integration is then used for the computation of topography-and
atmosphere-generated components of the mean gravity, while the combined solution for the downward continuation of gravity
anomalies and Stokes’ boundary-value problem is utilized in computing the component of mean gravity disturbance generated
by mass irregularities within the geoid. On application of this explicit formulism a theoretical accuracy of a few millimetres
can be achieved in evaluation of the geoid-to-quasigeoid correction. However, the real accuracy could be lower due to deficiencies
within the numerical methods and to errors within the input data (digital terrain and density models and gravity observations). 相似文献
152.
Summary The three-dimensional mesoscale cloud-resolving model ARPS (Advanced Regional Prediction System) was used to investigate the
dispersal of an inert seeding agent within a cumulonimbus (Cb) cloud developing from two different initial states. In this
paper, we stress the influence vortices in the cloud have on seeding agent dispersion. If a strong directional ambient wind
shear is present in the lowest layer, a vortex pair formed at the flanks of the simulated cloud. Following the velocity field,
a considerable amount of the injected seeding agent would be thrown out to the rear of the cloud, where both updrafts associated
with vortices and downdrafts occurred. After a short time the agent was present only in the cloud periphery. If the Cb cloud
developed under conditions where directional ambient wind shear did not exist, seeding agent dispersion would be quite different.
In this case, almost all the seeding agent was transported into the main updraft, while the residence time of the agent within
the cloud was longer due to the weaker cloud dynamics. Therefore, we must pay attention to whether or not the cloud contains
vortices when we make the decision where to seed. This is necessary in order to minimize the loss of seeding material. 相似文献
153.
Summary A couple of different techniques for implementing the variable resolution within numerical models of the atmosphere that use
quasi-uniform grids are estimated and compared based on their merit in the simple linear advection experiments. These techniques
are: grid stretching, Schmidt transforming and grid overlapping. The quasi-uniform grids are: a conformal cubic and an octagonal
grid. The techniques for the variable resolution are evaluated from the perspective of their effects on numerical solution
and the practicality of their application. Our analysis suggests that the grid stretching is for now the most optimal choice.
However, a special form of grid overlapping is presented that has potential to become a viable alternative in the future. 相似文献
154.
Dieter Kelletat Sander R. Scheffers Anja Scheffers 《Pure and Applied Geophysics》2007,164(2-3):413-431
The Andaman-Sumatra Tsunami of Dec. 26, 2004, was by far the largest tsunami catastrophe in human history. An earthquake of
9 to 9.3 on the Richter scale, the extension of waves over more than 5000 km of ocean and run-ups up to 35 m are its key features.
These characteristics suggest significant changes in coastal morphology and high sediment transport rates. A field survey
along the west coast of Thailand (Phuket Island, Khao Lak region including some Similan Islands, Nang Pha mangrove areas and
Phi Phi Don Islands) seven to nine weeks after the tsunami, however, discovered only small changes in coastal morphology and
a limited amount of dislocated sediments, restricted to the lower meters of the tsunami waves. This is in striking contrast
to many paleo-tsunami's events of the Atlantic region. Explanations for this discrepancy are sought in:
a. Mechanics of the earthquake. A rather slow shock impulse on the water masses over the very long earthquake zone,
b. Shallow water in the earthquake zone, and
c. Bathymetry of the foreshore zone at the impacted sites. Shallow water west of Thailand has diminished wave energy significantly.
The differences in geomorphological and sedimentological signatures of this tsunami compared with many paleo-tsunami worldwide
makes it unsuitable to be used as a model for old and future tsunami imprints by an event of this extreme energy and extension. 相似文献
155.
Summary The green feldspar in alkali granite from the Avdar deposit of decoration stone (150 km W of Ulan-Bator) has been identified by means of physical and chemical methods as amazonite. Its structural state corresponds to that of microcline with a high degree of triclinicity and displaying the following anomalous dimensions of the unit cell (nm):a=0.8568,b=1.2967,c=0.7217 nm, =90.732, =115.851, =87.702°;V=0.72115 nm3.The amazonite contains in increased amount of Pb (1950 ppm) as well as of Rb (1.15 mass %). The genesis of this amazonite is associated with younger metasomatic processes in the alkali granite.
With 1 Figure 相似文献
Amazonit aus dem Alkali-Granit des Avdar-Massivs, Mongolei
Zusammenfassung Der grüne Feldspat im Alkaligranit aus der Dekorationsstein-Lagerstätte im Avdar Massiv (150 km W von Ulan-Bator) wurde auf Grund physikalischer und chemischer Methoden als Amazonit bestimmt. Sein Strukturzustand entspricht demjenigen eines Mikroklins, der eine hohe Triklinität und anomale Elementarzelle aufweist (in nm):a=0.8568,b=1.2967,c=0.7217 nm, =90.732, =115.851, =87.702°;V=0.72115 nm3.Der Amazonit hat einen erhöhten Gehalt an Pb (1950 ppm) und an Rb (1.15 Gew.-%). Die Genesis dieses Amazonits ist mit jüngeren metasomatischen Prozessen im Alkaligranit verknüpft.
With 1 Figure 相似文献
156.
Josef Bochníček Tomáš Zelinka Reviewer T. Kolbenheyer 《Studia Geophysica et Geodaetica》1981,25(4):411-412
Summary The authors prove that the solution of Laplace's equation under Neumann's boundary conditions can be transformed to an advantage into determining the field which is generated by charges, induced by the external field at surfaces of discontinuity. 相似文献
157.
Summary The changes of the anisotropy of magnetic susceptibility of igneous rocks, induced by a magnetic field, are studied. It is proved that changes in the degree of anisotropy of susceptibility and of the orientation of the susceptibility ellispoid of specimens occur due to the configuration of the domain structure under the effect of the magnetic field. The influence of this effect on the total anisotropy of rocks depends on the degree of anisotropy due to the shape factor and on the stability of the domain structure. A model concept is presented, explaining the qualitatively different pattern of the changes of the anisotropy of susceptibility under the effect of the magnetic field in various directions of the specimens. 相似文献
158.
Summary A new computer-oriented algorithm GSO is presented for solving overdetermined systems of linear observation equations according to the principle of the least-squares method. The matrix of the system of observation equations may be of deficient rank. In this case the algorithm leads to the vector of unknowns with a minimum Euclidean norm. Alternatively, it is possible to minimize the norm of a subvector formed by a selected group of unknowns. The weight coefficient matrix, corresponding to the vector (subvector) of unknows, has the least possible trace. The algorithm GSO is based on the Gram-Schmidt Orthogonalization of suitably defined augmented matrices. The establishing and solving of normal equations is not necessary. Apart from the unknowns and residuals, GSO also determines the factorized weight coefficient matrices of the adjusted values.Presented at the I.A.G. International Symposium on Optimization of Design and Computation of Control Networks, Sopron, Hungary 1977. 相似文献
159.
Summary The problem of the elastic properties of a medium composed of thin anisotropic layers is treated. The study is based on the conditions of stress and strain and on Hooke's Law under the assumption of close contact between the layers. The algorithm described is suitable for a computer.Dedicated to RNDr. Jan Pícha, CSc., on his 60th Birthday 相似文献
160.
Summary The values of the electrical conductivity, recorded during the heating and cooling cycle, of eclogites and basalts are compared. The observed difference in the values is explained by reversible and irreversible changes which take place in the samples. 相似文献