Spatial Relation Resolution and Spatial Relation Abstraction

This paper attempts toregard spatial relation transformationas an important process in map gener-alization. The spatial relation generali-zation can be divided into the compo-nents of abstraction: topology, dis-tance and orientation. The concept‘ spatial relation resolution' is intro-duced to describe the constraints ofrelative spatial relation. On the basisof nine intersection models, the cardi-nal direction models and the iso-dis-tance-relation models, this paper givesthree sorts of relation resolution repre-sentations for topological, distance andorientation relation, respectively. Twomapping implementations in map gen-eralization is discussed.

Categorical Database Generalization

This paper focuses on the issues of categorical database gen-eralization and emphasizes the roles ofsupporting data model, integrated datamodel, spatial analysis and semanticanalysis in database generalization.The framework contents of categoricaldatabase generalization transformationare defined. This paper presents an in-tegrated spatial supporting data struc-ture, a semantic supporting model andsimilarity model for the categorical da-tabase generalization. The concept oftransformation unit is proposed in generalization.

Layering-based Breakpoint Handling in Contour Line Extraction

This paper deals withthe automatic connection of contourlines extracted from a scanned browngeographical map. For the variety oftopographical elements contained on amap, the factors causing the interrup-tion of contour line are also multiform,which make the connection task verydifficult. On the basis of separatingthose elements always making the con-tours break and regarding them as ref-erent layers, a layering-based methodis presented. The purpose is to takeinto account property information (likeinclination and configuration) of con-tour lines when they come across otherdifferent symbols, such as gully, cliff,dry land and elevation annotation etc.In this paper, the authors propose thatit should be far more effective and di-rect to adopt different algorithmic op-erators to different factors than usingsingle one operator to all.

The Spatial Characteristics of a Line and Their Application to Line Simplification

This paper discusses the spatial knowledge related to a line ,and the characteristic points of lines is detected.According to the requirements of line generalization,new algorithms for identifying characteristic line points are presented.These characteristic points are used to improve the algorithms of line generalization.An algorithm for identifying bends is shown.In this paper,improved algorithms based on those by Douglas_Peucker,Visvalingam and Whyatt are shown.In this test,the progressive process of line generalization is emphasized.

Measurement of Similarity for Spatial Directions Between Areal Objects

Similarity for spatial directions plays an important role in GIS. In this paper, the conventional approaches are analyzed. Based on raster data areal objects, the authors propose two new methods for measuring similarity among spatial directions. One is to measure the similarity among spatial directions based on the features of raster data and the changes of distances between spatial objects, the other is to measure the similarity among spatial directions according to the variation of each raster cell centroid angle. The two methods overcome the complexity of measuring similarity among spatial directions with direction matrix model and solve the limitation of small changes in direction. The two methods are simple and have broader applicability.

Models for Analyzing the Driving Force of Cultivated Land Supply Change

This paper focuses on a series of quantitative an al ysis models, such as grey relational analysis model, hierarchical cluster an alysis model, principal component analysis model, linear regression model and elastic coefficient model. These models are used to analyze the comprehensive function and effect of driving forces systemically, including analysis on featur es, analysis for differentiating the primary and the secondary, analysis on comp rehensive effects, analysis of elasticity, analysis of prediction. The primary a nd characteristic factors can be extracted by analysis of features and analysis for differentiating the primary and the secondary. Analysis on prediction an d elasticity can predict the area of cultivated land in the future and find out which factors exert great influence on the cultivated land supply.

Impacts of Overgrazing and Reclamation on Soil Resources in Rangeland Ecosystems in Huailai Basin, Hebei, China

The soil constituents and relations between the variation of soil resources and plant communities in three adjacent sites representing the overgrazing, reclamation and comparatively undisturbed communities respectively were quantified and examined in study area in Huailai Basin, Hebei Province, China. There have been significantly greater constituent of C, N, P in the soils of shrubland site. Corg, Ntotal, Navail and Pavail were between 1.18 and 3.90 times more concentrated in the soils of shrubland site in comparison with the other two sites. Although the Ptotal concentration was lower in shrubland soils than in overgrazed rangeland soils, the Pavail concentration, however, was significantly greater in the soils of shrubland site, and increased by 59.1% and even 289.6% in the soils of shrubland site comparing to those in the soils of range-land and millet field sites. Among the three sites, CV exceeding 40% were found for SO4, Cl, and F ion. The CV of organic carbon also exceeded 40% but only in the soils of millet field site. The highest CV were found for F, SO4 ion in the soils of shrubland and overgrazed rangeland sites, while for Cl and SO4 ion in those of millet field site. The results also showed that the introductions of shrubs are of vital importance for the accumulation of soil nutrients and maintenance of soil fertilities, and also for the restoration and reconstruction of desertified ecosystems.

Integration and Sharing of Geo-spatial Data Based on Data Engine

Through analyzing theprinciple of data sharing in the data-base system, this paper discusses theprinciple and method for integratingand sharing GIS data by data engine,introduces a way to achieve the highintegration and sharing of GIS data on the basis of VCT in VC++, and pro-vides the method for uniting VCT intoRDBMS in order to implement a spa-tial database with object-oriented datamodel.

Discriminant Analysis on Land Grading

This paper proposes the discriminant analysis on land grading after analyzing the common methods and discussing the Fisher’s discriminant in detail. Actually this method deduces the dimension from multi to single, thus it makes the feature vectors in n \|dimension change to a scalar, and use this scalar to classify samples. This paper illustrates the result by giving an example of the residential land grading by the discriminant analysis.

Interactive Generalization on Large-Scale Topographical Map Supported by a Database Platform

This paper makes astudy on the interactive digital gener-alization, where map generalizationcan be divided into intellective reason-ing procedure and operational proce-dure, which are done by human andcomputer, respectively. And an inter-active map generalization environmentfor large scale topographic map is thendesigned and realized. This researchfocuses on: ① the significance of re-searching an interactive map generali-zation environment, ② the features oflarge scale topographic map and inter-active map generalization, ③ the con-struction of map generalization-orien-ted database platform.

Photoregulated or Energy Dependent Process of Hormogonia Differentiation in Nostoc sphaeroides Kutzing （Cyanobacterium）

Hormogonium, which was thought to play an important role in the dispersal and survival of these microorganisms in their natural habitats, is a distinguishable developmental stage of heterocystous cyanobacteria. The present study examined the effects of different light conditions and sugars on the differentiation ofNostoc sphaeroides Kiitzing to the hormogonia stage. Results showed that differentiation of hormogonia was light dependent in the absence of sugar, but that close to 100% of cyanobacteria differentiated to hormogonia in the presence of glucose or sucrose, irrespective of the light conditions. This differentiation was inhibited, even in the presence of sugars, upon application of an inhibitor of respiration. Following the testing of different sugars, the effects of different lights were examined. It was found that 5-10μmol·m^-2·s^-1 photon flux density was optimal for hormogonia differentiation. One hundred percent differentiation was obtained with white light irradiation, in contrast with irradiation with green light (80% differentiation) and red light (0-10% differentiation). Although they showed different efficiencies in inducing hormogonia differentiation in N. sphaeroides, the green and red radiation did not display antagonistic effects. When the additional aspect of time dependence was investigated through the application of different fight radiations and an inhibitor of protein synthesis, it was found that the initial 6 h of the differentiation process was crucial for hormogonia differentiation. Taken together, these results show that hormogonia differentiation in N. sphaeroides is either a photoregulated or an energy deoendent orocess.