1996 Vol. 21, No. 2
A new algorithm of spherical harmonic synthesis on satellite gravity gra-dient component is presented in the paper.Moreover,the results of test computa-tions are given over two special areas in China from earth's gravity field model WDM94,which shows that the method is very effective.
In this paper,the flattening,mass,gravity,pressure,mean principal mo-mentum of inertia,difference of principal momentum of inertia at any radius in the interior of the Earth are computed.Their polynomial and discrete digital representa-tions are given in aecordeuce with that of the Preliminary Reference Earth Model (PREM).
Applying the theory of strain analysis and based on the data of the national A order and B order GPS network,the national astrogeodetic network has been checked.Through the strain analysis,the range and the feature of expanded and contracted deformation,wrest deformation and turn of the national astrogeodetic network have been shown clearly.According to the analysis result the authors pre-sent some suggestion for the choice of coordinate transformation model,and give a reasonable coordinate transformation model.
In this paper,the mechanism of periodic errors of Lacoste and Romberg (LCR)G gravity meters is analysed.The principles and methods of calibration of pe-riodic errors are also discussed.By using the three terms of calibration observations of LCR-G920 and LCR-G922,the further study on periodic errors of LCR-G gravity meters is taken,and some conclusions are reached.
In this paper the dimensions and visualisation of spatial data are intro-duced.Two kinds of spatial data structures in 3D GIS are discussed.One is based on surface representation and the other is based on solid representation.Included are:boundary representation(BR),constructive solid geometry(CSG),non-uniform reasonable B-spline surface(NURBS),octree and tetrahedral irregular network. The characteristics and possible applications of these structures are also analysed.
On the basis Of papers[1,2],the positional errors of area primitives in GIS are discussed in this paper.And accuracy indicators for estimating positional error of area primitives and area of uncertainty region are also given.These are of some value to both further researches and industrial production.
This paper is on the basic principles for developing the universal expert. system of remotely sensed image understanding.The setting up of fact-base files, the knowledge expression and acquisition,fussy inference and the connection with the system of remote sensing image processing and GIS software are discussed in detail.RSSTAR,as one of the so-called universal expert systems for remote sensing image analysis has been introduced with its development and preliminary effect.
The quantitaive expression of topographic features is made by applying fractal theory.Three dimensions;line dimension,box dimension 1 and box dimen-sion 2,are proposed,and their characteristics,which are used in topographic ex-pression,are analysed in detail.At last the fractal dimensions of some typical land-forms are determined.
This paper is about the study on the constructive elements,characteris-tics and utility of the comparative process.The authors have also presented a model of theory construction in comparative process and some experimental facts with the model.
Combined with the master plan for Jinkou,one of the new satellite towns of Wuhan Municipality,a GIS approach is used to make the land use suitabil-ity evaluation before making the master plan.The principle,methodology,procedure and software are disscussed in this paper.The results shows that the GIS approach is reliable and suitable to such land suitability evaluation.
A measurement method of optical transfer function(OTF)is discribed in this paper,in which charge-coupled device(CCD)in space camera,with an image sampler joined up with a PC,is used directly as an optoelectronic element.Knife edge scanning with high precision and high sampling density and digital Fourier analysis method is adopted.After measuring the defocal MTF curve of space camer-a,the best imageing position is determined precisely.
A method for judging charge-coupled device(CCD)imaging sensor by modulation transfor function(MTF)is presented.The formulas for calculating the MTF of CCD imaging sensor are also given.This paper centers on using MTF to analyze the spatial frequency response of ideal CCD systems.The resultant infor-mation will allow more accurate design of systems incorporating discrete devices such as CCDs.
This paper introduces the matrix vector transformation of Chinese char-acters for Windows.Non-scale zooming and arbitrary rotations can be realized,and the vector Chinese charactors can also be displyed by using various colors.The pro-cess to discrete points and the rectilinealiy method after edge tracing are introduced too in this paper.
In this paper,we study the following kind of backward nonlinear stochastic evolution equation x(t)+∫tTf(s,x(s),y(s))ds+∫tTy(s)dW(s)=X Under a rather mild assumption,only a local condition is satified.Local and global existence and uniqueness results are obtained.Where(Ω,F,P,W,Ft)is a stan-dard Wiener process,for any given(x,y),f(·,x·y)is an Ft-adapted process, and X is Ft-measurable.