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61.
62.
When height networks are being adjusted, many geodesists advocate the approach where the adjustment should be done by using geopotential numbers rather than the orthometric or normal heights used in practice. This is based on a conviction that neither orthometric nor normal heights can be used for the adjustment because these height systems are not holonomic, meaning–among other things–that height increments (orthometric or normal) when summed around a closed loop do not sum up to zero. If this was the case, then the two height systems could not be used in the adjustment; the non-zero loop closure would violate the basic, usually unspoken, assumption behind the adjustment, namely that the model claiming that height differences are observable is correct. In this paper, we prove in several different ways that orthometric and normal heights are theoretically just as holonomic as the geopotential numbers are, when they are obtained from levelled height differences using actual gravity values. This disposes of the argument that geopotential numbers should be used in the adjustment. Both orthometric and normal heights are equally qualified to be used in the adjustment directly. 相似文献
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The problem of judging on model deficiency in S.L.R. data treatment is considered. In particular the correlation analysis
of residuals of adjusted orbits is used to show the presence of unmodelled signals. This analysis seems suitable at least
for a proper preprocessing of S.L.R. data, in the sense of being an efficient procedure of outliers rejection. 相似文献
66.
Finite covariance functions 总被引:1,自引:0,他引:1
Because of the full covariance matrices and the computer storage limitations the number of measurements which can be handled
by the collocation method simultaneously, is limited. This paper presents a method to compute covariance functions with a
finite support yielding sparse covariance matrices. The theoretical background is pointed out and, for the one- and two-dimensional
case, special functions are developed which can be combined with the usually used covariance functions to get a “finite covariance
function”. Simulated examples to demonstrate the behaviour of different solution methods to solve these special, sparse covariance
matrices supplement our investigations. 相似文献
67.
The two Altimetry-Gravimetry linearized boundary value problems, both characterized by gravity anomaly boundary data on the continents, while on the oceans either the gravity potential or its radial derivative is assumed to be known, are investigated in their modified version, in the spherical boundary approximation. A constant unknown bias is added to the data set on the oceans, while a vanishing zerodegree harmonic component is assumed as additional constraint. Existence, uniqueness and regularity results are obtained, it is proved that, in order to obtain regularization of the solution, not only regular data must be imposed, on the continents and on the oceans, but suitable constraints on the coast line are needed. 相似文献
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69.
We study the possibility that large flux differences between the poles and the equator at the bottom of the solar convective zone are compatible with the small differences observed at the surface. The consequences of increasing the depth of the convective zone due to overshooting are explored.A Boussinesq model is used for the convective zone and we assume that the interaction of the global convection with rotation is modelled through a convective flux coefficient whose perturbed part is proportional to the local Taylor number. The numerical integration of the equations of motion and energy shows that coexistence between large pole-equator flux differences at the bottom and small ones at the surface is possible if the solar convective zone extends to a depth of 0.4R
. The angular velocity distribution inside the convective zone is in agreement with the -dynamo theories of the solar cycle. 相似文献
70.
The problem of phase ambiguity resolution in global positioning system (GPS) theory is considered. The Bayesian approach
is applied to this problem and, using Monte Carlo simulation to search over the integer candidates, a practical expression
for the Bayesian estimator is obtained. The analysis of the integer grid points inside the search ellipsoid and their evolution
with time, while measurements are accumulated, leads to the development of a Bayesian theory based on a mathematical mixture
model for the ambiguity.
Received: 29 March 2001 / Accepted: 3 September 2001 相似文献