1981 Vol. 6, No. 2
In this paper several methods of solution of the Stokes problem with an accuracy oJ the order of flatening square are described first.Then the ralationship between the Molodensky,Mone and Fang Jun formulas is derived.Finally,a comparison of the formulas discussed above is perfomed on the model.
In this paper the Datum-shift parameters are determined using the map of geoidal undulation based on Rapp's 180×180 solution and the computed values of geoidal undulation with respect to WGS-72 system as well as the map of geoidal undulation with respect to local geodetic coordinate system-1980 of our country.The comparison of the results computed in this paper with the result which has been obtained by using the data of astronomical,geodetic,gravimetric and Doppler observations in our country manifest that the both results are consistent with an accuracy of ±10m.
In this paper the characteristics of one of the well known DTM interpolation method,the multisurface function method,are studied.As a result,a very simple cubic surface as kernel function of the multisurface function without any parameter has been found to be better than the hyperboloid one which was highly recommended by Hardy.This cubic surface is suitable for any type of terrain as shown in some computation examples.
In this paper a method for the forming of orthogonal additional parameters in a self-calibrating bundle block adjustment is described and the effect of each kind of systematic errors represented by Ebner's additional parameters on the adjusted results is analyzed.All these are deemed necessary for the understanding of the functional rule of systematic image errors as well as of the efficiency of the compensation of systematic errors by using the self-calibrating adjustment.These will help us also to analyze the possible strong correlations between the additional parameters and some other unknowns,to choose the additional parameters correctly and to know how to locate the ground control points more profitably.
In this paper,the correlation analysis of a self-calibrating bundle block adjustment and the test of significance of additional parameters are carried out by the use of a selected orthogonal additional parameter set.The main objects of study are namely:the theoretical accuracy of the adjusted coordinates and the additional parameters,the correlation coefficients among the additional parameters and between the additional parameters and the ground point coordinates,the choice of additional parameters according to the test of significance.All of these studies are performed with different weights of additional parameters.The basic conclussions obtained are:(1) The theoretical accuracy of adjusted coordinates and additional parameters as well as the correlation between additional parameters and ground point coordinates are related to the choice of the weight of additional parameters.(2) Under certain geometrical conditions some additional parameters of an orthogonal parameter set might be highly correlated with ground point coordinates.(3) From the correlation analysis by the use of synthetic data for the given geometric figure of the block and the adopted additional parameter,we can find out those parameters which are very sensitive to their weights or which can not be easily determined exactly or which will bring out high correlations among the unknowns.If those parameters are removed from the equations or are given a bigger weight,the self-calibrating adjustment will be able to obtain a reliable accuracy improvement.In this case,the adjusted results will become insensitive to the weight of additional parameters.(4) Vice versa,if the weight of additional parameters can be correctly determined according to their signal-to-noise ratio,the correlation analysis and the test of significance of additional parameters can he exempted from the adjustment procedure when the imitation errors for systematic errors are not considered.Thus,an efficient accuracy improvement can be expected.At the end of this paper some suggestions are made in accordance with the investigations in、and this paper for the proper use of self-calibration in production work.
On the basis of and,this paper put forward two dynamic adjustment schemes of repeated observations in different epochs:(1) a dynamic adjustment of linear kinematic model with a velocity parameter λ;(2) a dynamic adjustment of nonlinear kinematic model with an acceleration parameter γ.This paper deals with the principle for the choice between these two adjustment schemes and the difference of the results from these two kinds of adjustments.Finally,some important characteristics of a dynamic adjustment of levelling networks are presented.
In this paper some problems in optimum design of engineering surveying control nets are studied:1.Optimization of net form All control points are divided into two kinds.The second kind of points which has certain ranges of selection is selected by the optimum seeking method.2.Optimum coordination between the precision of observations of sides and angles.The optimum coordination is discussed separately for the case of triangulation-trilateration net,triangulation net with observing some sides and trilateration net with observing some directions(or angles).3.Optimization of the distribution of observation weights.This problem is solved by seeking the optimum proportion of weights distribution.
Based on the project programme of high precision traverse in our country,the questions whether the lateral accuracy can be increased by adding measuremnts of Astronomical Azimuths and what density is suitable for the distribution of Astronomical Azimuth are discussed.In this paper,the obtained conclusion is different from that presented by K.Borkowski,and the shortcoming in the documentis also discussed.
The design method of gravity network on the basis of the principle of the lineaprogramming and the sequential optimization is given.The constraint of the linear programmirg is(AT⊙AT) P≥N'0.The coefficient,matrix of normal equation which is comr puted strictly is used as the standard of controlling accuracy.Since the linear programming includes all practical and feasible observation lines,so the result is feasible.After the computation by using the simplex method the observation lines of which the weights are zero are eliminated and all observation lines with the practical weights are taken as the basis of the sequential optimization.In the course of the sequential optimization two equations(maxQii=min.tr Q· Ci=min) are used as the standard of comparison in order to improve the homogeneity of the accuracy of the network.The new gravity basic national network has been designed on the basis of the method designed above.The questions about the accuracy of gravity network,absolute gravity stations,the gravity base line and so on have been discussed.