1987 Vol. 12, No. 4
This paper is a report of the study on the combined adjustment of satellite and terrestrial network,which is a research project undertaken in recent years.In this paper the following points have been discussed:——the WUS model with seven parameters and model appending VLBI observations.(the former likely makes the deviation of the translation parameters minimum and the latter will be able to keep the scale parameter of the terrestrial network separate from the scale parameter of the satellite network).——the method of the combined adjustment by means of least squares collocation and build-up of observation equations in different coordinate system.——The analyses of the errors in the combined adjustment in which emphasis is placed on the concept of "Influence rate".——A development of the combined adjustment program with multifunction such as the location of the gross errors,estimation of the variance components;the hypothetic test of the transformation parameters and automatic selection of models with appropriate nember of transformation parameters and so on.——The application of the combined adjustment to North-West satellite network and terrestrial network.
The concept of fourdimensional integrated geodesy is outlined and the dynamic observational equation for gravity vector is developed according to the basic idea and conceptual models presented by Hein and Grafarend.The time-dependent effects on the observations caused by Earth tide and crustal movements are included in the equations.
The discrepencies forward and backward in rerunning levels are usually used as statistic in the accuracy estimate of levelling.The existing methods concerned,however,don't involve verifications on correctness of the error models for the discrepencies,even lack strict and feasible formulae for the estimate.In this paper,the MINQUE of variance components is applied to estimating the variances,and some statistical tests and optimal option of the error models are presented based on the principle of regression analysis.The methods of the estimation and analysis are not only analytically strict but also more feasible.Finally,the advantages and effectiveness of the methods are examined.through a testing computation using first-order class Ⅰ levelling of 175 sections and lines.
This paper discusses how to utilize microcomputers and the.relevant hardware interfaces for gathering,analyzing and processing the on-site information of 2048 weaving machines in a weaving shop of a textile factory.This gathered information is to be sent,on the one hand,to a display centre,where it is demonstrated for the managers to master all the site conditions and on the other hand,to a IBM-PC for statistics,quality analysis and report form printing.Considering that it's quite a long distance from the information gathering interfaces to the site or the display centre,the interference resulting from longline transmission and the corresponding technical measure adopted are dealt with to guarantee the system reliabily.
The self-calibration of metric camera in a single station without ground controls is a method using pure photogrammetric information,Starting from the collinearity equation and considering the decenter of projection center from the rotation center of camera,the geometric relationship between vertical and oblique photographs and its linearized error equation are derived.A FORTRAN program has been developed in VAX-11/750.The results are given both for simulation and practical data.
This paper briefly explains four kinds of topological relations on maps-incidence relation,neighbourhood relation,overlap relation and co-area relation as well as the relations among them.Also it expounds the possibility of obtaining those topological relations by computing,namely topological relation data can be worked out from the geographical coordinate data on maps.Meanwhile,method and procedure of the computation are briefly discussed.
Not one of quota model and structure model can be omitted for the selection of cartographic objects in cartographic generalization of computer-assisted cartography and the expert system in map-database.Under the control of the quota,structure model can be used for selecting concrete object.But it muse be considered that a lot of factors act as role in the selection of the concrete objects.Since the relationships of them are generally veiled and arc of universal fazziness,it is either complication or loss of more cartographic imformation to process them with tranditional two-value logic method.In this article,as an example of the selection of rivers,it is initially discussed to use fuzzy sets theory for establishing the structure model of the selection of cartographic objects and it is simply explained to use a simple sample.
The least squares estimator is a minimum and unbiased estimator.The parameter estimates are based on the minimum sum of residual spuares.The parameter estimates may be reliable if the coefficient matrix ATA is nearly a unit matrix.However,minimizing the sum of residual squares may not guarrantee that the variances of the parameter estimates are small if the matrix ATA is ill-conditioned.The distances between parameter estimates and their true values may be reduced by using the ridge estimator.In other words,the ridge estimator may be used to improve the accuracies with regard to the parameters of imprecised estimates.
This paper sets forth the theory which is used for analysing the effects of observed elements in notwork,and gives four indexes corresponding with it.The relation between the effects of observed elements and the configuration of network is discussed,also the relation between the effects and the accuracy matching of observed elements.Meanwhile,the geometric significance of the requisite obsevational component is shown.
With the development of marine surveying techniques,in order to obtain the position parameters as accurate as possible more attention should be paid to the data-processing.For example,in the practice of positioning for marine geophysics exploration,it is often difficult to estimate the position using coventional method because of the existence of gross error in the measurements.At present,there is little work done concerning outliers in marine surveying.This paper tries to solve the following problems:1) How to discover the outliers in measurements and to obtain accurate position parameters.2) Put forward some suggestions on the field work.