1998 Vol. 23, No. 2
In this paper,the characteristics of new-generation quasi-geoid with high resolution and high accuracy in China are discussed. The applied formulae using remove-restore techniques are presented. The rigorous methods and algorithms for computing Stokes formula and estimating the accuracy of height anomaly are also described.
Grey correlation analysis and fuzzy clustering are used in multi-point analysis. Integrated deformation is analyzed and spatial prediction model is established combining the geological qualitative analysis with mathematical quantitative analysis to the T0~T6, area of Lian Zi dangerous rock mass in The Three Gorges. The result shows that the multi-point spatial nonlinear prediction model used for Integrated deformation prediction with poor data in formation is a recommended method.
The presentation briefly introduces the basic principle of Expert System (ES) at first,then discusses the probability of it's application to the optimal design of survey control network. A survey Control Network Optimal Design Expert System (CONODES) is developed based on the General Adjustment Program (GAP) by using the expert system building tool-ART. The knowledge presentation and it's inference strategy are demonstrated in detail in this paper. At last,the comparison of it's advantage and disadvantage with the traditional approach for optimal design of survey control network is made.
This paper presents the state model and deals with the data processing methods for various deformation monitoring nets and target tracking problems. Based on the matrix outer product method,an efficient filtering algorithm is developed to perform the state estimation and prediction of the state variables. The theoretical analysis and numerical results show the advantages over the conventional methods in terms of efficiency and numerical stability.
In this paper,an assessment of measured ionospheric vertical total electron content (VEC) in Hong Kong area based on dual GPS data which are from the Hong Kong DGPS universal reference station is presented. The variances of VEC on four seasons in one year are given, and the variant regularity of VEC in one day is also analyzed. It is favorable for building a practical model of ionosphere in Hong Kong area.
In this paper,a definition of three dimensional convex hull of a set of spatial points is presented. The partitioning index method based on octree for spatial points is proposed. An algorithm for three dimensional convex hull creation is developed and some tests are made to confirm the algorithm.
The problem of how to deal with the three dimensional representation and analysis of terrain surface within the two dimensional GIS, such as GeoStar,is examined in this paper. It is stressed that the concept of visualization is expanded into the whole GIS system. it's much more than visualization,i. e. it enables the data-input more flexible,data interpolation more powerful,model viewing and manipulation capabilities more highly interactive. The author proposes integrating DEM and digital orthographic image with the basic data of 2D GIS to provide 3D realistic environment for geo-referenced multidiscipline applications.
First at the base of point Voronoi diagram,the definition of the spatial object's Voronoi diagram is brought forth. Then according to spatial object's Voronoi diagram, the definition of spatial adjacency are given and the applications in spatial query are discussed. At last some experiment results are given.
In the past few years,the Voronoi spatial data model has attracted more and more attentions. However,the Voronoi tessellations used in the Voronoi spatial data model are ordinary and the obstacles are not taken into account. Modifying ordinary Voronoi diagram with linear obstacles is one of the two basic approaches in generation Voronoi tessellations with obstacles. The authors proposed to aggregate the segmented linear obstacles for forming united partitions. The algorithms and techniques for modifying the ordinary Voronoi tessellations based on these united partitions are discussed further in this paper. The VORDLL is used in the experimental work.
In this paper, four constructors, i. e., tuple, set, list and temporal constructors were introduced to construct an algebraic model of structure of temporal objects. Transfor-mations from various traditional temporal relational data models to the temporal object model were illustrated. The study has shown that the algebraic model of structure of temporal objects has more advantages over temporal relational models in complex structures and temporal semantics modeling.
In order to model and represent the spatial-temporal process of land use dynamic change present, this paper analyzes the characteristics and forms of land use change and proposes a temporal data structure about land use types in Land Resource information System (LRIS or LIS), which can handle the temporal problem.
This paper presents a new image matching method based on wavelet transform.This method uses wavelet transform to decomposite the image and generates the pyramid image structure. Using parallax and feature constraint in the relaxation image matching, the reliability can be improved.
By building grey system model the yearly agriculture crop yields were predicated.The post--effectiveness of nature and society have been taken into consideration. And greyMarkov chain approach was used. The prediction reasults were resonable.
Using the green herbage yields, environment and the remote sensing (RS) data observed in different grassland types in Fukang County, Xinjiang from 1994 to 1997, the correlation analysis and the estimating yield methods were studied by measns of 3S technology. The methods of images processing, information collecting and using information, links of RS data and grassl and data were further developed in this paper. The results show that the total accuracyes of the remote sensing estimating and forecasting green yields were above 75% in large areas.
Essential information for generating the digital map and associated database is discussed in this paper. Several digital map dependent functions, including map representation,initialization of the AVLN system, position and location, route determination, and route guidance are mainly described.
In this paper, the characteristics of the multimedia data model has been analyzed.One model for the organization and storing multimedia data, namely the multimedia data model based on the non first normal form (NF2) has been proposed based on the theory of relation database and extension for the non first normal form. With the help of this model, the multimedia data such as image, sound, video and so forth and embedding structure of multimedia data can be effectively stored and managed.
Taking the thematic charts in thematic mapping for example, a new method based on pattern-plate for thematic mapping is given in this paper. Also the conception of patternplate, the design principles of pattern-plate tool and the method for establishing patternplate library are discussed.
Based on the introduction of the basic principles of teletext, synchronous separation of video signals, abstraction of row order pulse signals, overlaying of graphical and teletext information by computer are presented and the basic idea of the design and the method of realization of the graphical and teletext information's receiving store and broadcast are mainly discussed in this paper. There are also detailed descriptions of the solution of share collision of buffer storage and the method of signal's abstraction during the procedure of design, which make the whole design complete and practicable.
Based on the analysis of special requirements of master calibration square wave in the partial discharge detection and discharge capacity calibration, the principle and hardware of calibrater and its applications in the power system are presented in this paper.
In this paper, causes for the change of early phase of cycle error with photoelectric ranger are analyzed. The new thought on the theory with cycle error is given. It is showed that some preblems should be noticed in the processing of the cycle error.