一种基于网络拓扑关系的地图匹配算法

地图匹配是车辆导航定位系统中提高定位精度的一种方法,其精度受定位数据、地图数据质量及坐标系转换关系的影响。在分析现有算法的基础上,提出了一种基于网络拓扑关系的地图匹配算法。该算法只需将GPS定位数据和G IS数据相结合,即可用算法的形式解决地图匹配中一些常见的问题。实验证明:该算法是一种精度高、效率好、实用性强的地图匹配算法,具有较好的实用价值。     

地图空间关系认知元素分析

分析了目前地图空间认知的几种理论研究。从地图学史的角度出发,应用几幅著名的中外古地图,指出符号、注记以及空间拓扑关系在地图发展变化中的不变性,认为这3种元素构成了地图空间关系认知的基本元素,并分析了这3种元素在地图空间关系构建方面所起的作用。最后提出了在网络环境下,这3种元素在大众制图中的指导意义。     

Comparison of relative permeability–fluid saturation–capillary pressure relations in the modelling of non-aqueous phase liquid infiltration in variably saturated,layered media

The characteristic functions relating relative permeabilities and capillary pressures to fluid saturations (k_r–S–P_c models) are of great importance for the modelling of sub-surface multi-phase flow and transport. In order to test their performance and to identify their important parameters, four well-known three-phase k_r–S–P_c models have been tested against published experimental data on non-aqueous phase liquid (NAPL) migration in the unsaturated zone. Both homogenous systems and systems with embedded heterogeneities have been analysed.     

空间方向关系形式化描述模型研究

空间方向关系形式化描述模型是空间关系研究的难点和重点，目前尚无完善的模型出现，因此进行其模型的研究意义重大。首先论述运用平面目标Voronoi图描述方向关系在理论上的可行性；然后详细阐述基于Voronoi图的空间方向关系形式化描述模型建立；为了验证模型的正确性，给出几个典型的算例；最后指出模型的优、缺点。     

Calculated Phase Relations in High-Pressure Metapelites in the System NKFMASH (Na2O-K2O-FeO-MgO-Al2O3-SiO2-H2O)

Using an internally consistent thermodynamic dataset and updatedmodels of activity–composition relation for solid solutions,petrogenetic grids in the system NKFMASH (Na₂O–K₂O–FeO–MgO–Al₂O₃–SiO₂–H₂O)and the subsystems NKMASH and NKFASH have been calculated withthe software THERMOCALC 3.1 in the P–T range 5–36kbar and 400–810°C, involving garnet, chloritoid,biotite, carpholite, talc, chlorite, kyanite/sillimanite, staurolite,phengite, paragonite, albite, glaucophane, jadeite, with quartz/coesiteand H₂O in excess. These grids, together with calculated AFMcompatibility diagrams and P–T pseudosections, are shownto be powerful tools for delineating the phase equilibria andP–T conditions of Na-bearing pelitic assemblages for avariety of bulk compositions from high-P terranes around theworld. These calculated equilibria are in good agreement withpetrological studies. Moreover, contours of the calculated phengiteSi isopleths in P–T pseudosections for different bulkcompositions confirm that phengite barometry is highly dependenton mineral assemblage. KEY WORDS: phase relations; HP metapelite; NKFMASH; THERMOCALC; phengite geobarometry     

Laboratory simulation of water-resources conservation by means of the layout of a series of ponds along a streambank

 The purpose of this research is to describe a water-storage method that is more reliable than reservoirs, and to study the efficacy of interception and storage of surface runoff in ponds. In this method, a series of ponds is laid out along a streambank so that interception of surface runoff can be increased and more water can be stored in the wet season for use in the dry season. The simulated results show that the structure of a pond, vegetation and the extent of land development, topographic slope, and the degree to which a pond penetrates an aquifer affect the efficacy of interception and storage of surface runoff in ponds. Received, May 1996 Revised, July 1997, March 1998 Accepted, October 1997     

Truncation error formulae for the disturbing gravity vector

Recurrence relations have been derived for truncation error coefficients of the extended Stokes' function and its partial derivatives required in the computation of the disturbing gravity vector at any elevation above the earth's surface. The corresponding formulae, the example of values of the truncation error coefficients for H=30.1 km and ψ₀=30^∘ and the estimations of truncation error are given in this article. Received: 26 January 1996 / Accepted: 11 June 1997     

模糊对象粗糙表达及其空间关系研究

空间数据的模糊性是当前GIS领域研究的难点之一。现有的GIS数据模型基本上还不具备对模糊性进行描述、处理和分析的功能 ,使得GIS对数据的处理容易造成信息损失。把粗糙集和模糊集对空间数据的模糊性和不确定性处理的优势结合起来表达模糊对象 ,即利用粗糙集处理由于知识的粒度性所造成的模糊性和不精确性 ;利用模糊集处理模糊对象原始数据所具有的不确定性 ,从而扩展了空间数据模型对模糊数据的表达能力 ,并详细研究了模糊面与模糊面以及模糊线与模糊面之间的拓扑关系     

波形长度分形维数在结构振动诊断中的应用

在Hausdorff维数和分配维数的基础上 ,采用拓扑映射技术 ,提出了振动波形长度分形维数的定义和计算公式 ,并对其数学严密性进行了证明。结合工程实例探讨了基于振动波形长度分形维数计算的结构振动诊断技术 :模型增长法和滑动窗法。该技术对于波形异常检测表现出精度高、抗噪能力强及自动快捷等优势 ,构成了一条分形理论用于结构振动诊断的有效技术路线 ,具有良好的应用价值。     

Plant water relations of thornscrub shrub species, north-eastern Mexico

As an approach to understand how diurnal and seasonal plant water potentials (Ψ) are related to soil water-content and evaporative demand components, the responses of six thornscrub shrubs species (Havardia pallens, Acacia rigidula, Eysenhardtia texana, Diospyros texana, Randia rhagocarpa, and Bernardia myricaefolia) of the north-eastern region of Mexico to drought stress were investigated during the course of 1 year. All study species showed the typical diurnal pattern of variation in Ψ. That is, Ψ decreased gradually from predawn (Ψ_pd) maximal values to reach minima at midday (Ψ_md) and began to recover in the late afternoon. On a diurnal basis and with adequate soil water-content (>0.20 kg kg⁻¹), diurnal Ψ values differed among shrub species and were negatively and significantly (p<0.001) correlated with air temperature (r=−0.741 to −0.883) and vapor pressure deficit (r=−0.750 to −0.817); in contrast, a positive and significant (p<0.001) relationship was found to exist with relative humidity (r=0.758–0.842). On a seasonal basis, during the wettest period (soil water-content>0.20 kg kg⁻¹), higher Ψ_pd (−0.10 MPa) and Ψ_md (−1.16 MPa) values were observed in R. rhagocarpa, whereas lower figures (−0.26 and −2.73 MPa, respectively) were detected in A. rigidula. On the other hand, during the driest period (soil water-content<0.15 kg kg⁻¹), Ψ_pd and Ψ_md values were below −7.3 MPa; i.e. when shrubs species faced severe water deficit. Soil water-content at different soil layers, monthly mean relative humidity and monthly precipitation were significantly correlated with both Ψ_pd (r=0.538–0.953; p<0.01) and Ψ_md (r=0.431–0.906; p<0.05). Average soil water-content in the 0–50 cm soil depth profile explained between 70% and 87% of the variation in Ψ_pd. Results have shown that when gravimetric soil water-content values were above 0.15 kg kg⁻¹, Ψ_pd values were high and constant; below this threshold value, Ψ declined gradually. Among all shrub species, A. rigidula appeared to be the most drought tolerant of the six species since during dry periods it tends to sustain significantly higher Ψ_pd in relation to B. myricaefolia. The remaining species showed an intermediate pattern. It is concluded that the ability of shrub species to cope with drought stress depends on the pattern of water uptake and the extent to control water loss through the transpirational flux.