基于CGA的建筑物程序化建模研究

CGA形状语法是一种新的模拟计算机图形的语言,能够程序化地产生高视觉效果和详细几何信息的建筑。它能够以很低的成本广泛地用于电脑游戏和电影等的建筑物建模。清晰的等级规则可以让用户方便地指定建筑物之间的层次关系。CGA形状语法表明它能够有效地产生大规模的具有非常详细程度的城市,能够解决以前大规模模型建立过程中在任意方向和形状方面的详细程度问题。     

GPS网形与GPS网质量的关系分析

基于GPS静态相对测量,基线数据处理采用双差观测值单基线解算的一般模式,讨论GPS网基线解算和3维无约束平差的公式,得出GPS网的质量与基线向量质量和GPS网结构有关,而与网形和点位无关,并通过实验数据,分析验证了这一观点,提出了一些有益的结论。     

Morphometric Comparisons Between Rogen Terrain and Hummocky Terrain

Visual interpretation of aerial photography suggests that certain geomorphological similarities exist between the hummocky terrain of central Alberta, Canada, and the Rogen terrain of Nunavut, Canada. This study statistically compares the two landform types based on measures of depression shapes and ridge orientations. Comparison of depression shapes indicates that two of three sample areas chosen from the hummocky terrain study area are statistically similar to those of the Rogen terrain study area. Analysis of ridge orientations indicates the ridge crests from two of three hummocky terrain sample areas, and ridge crests from within the Rogen terrain study site all exhibit a preferred trend. Variability in the process of formation may explain why only particular areas throughout the hummocky terrain exhibit patterns similar to the Rogen terrain and others do not. Statistical similarities in two-dimensional form between the hummocky terrain of central Alberta and the Rogen terrain of the Northwest Territories however, suggest that these landforms may have a common or similar origin.     

Environmental “Education”: The Last Measure Of Man

Promotion of nonacademic geography is a logical response to curtailment of opportunity for new teaching careers. Yet this necessary redirection of effort must be accompanied by renewed dedication to education and especially to nonprofessional undergraduate education. The case for geography in the liberal arts curriculum may well be a strong one, but questions about what we can offer need to be raised more frequently among ourselves if we are to respond effectively when such questions are asked by outsiders.     

缅甸其培水电站恩梅开江断裂构造特征及活动性评价

综合野外地质调查、氡气测量、石英形貌扫描(SEM)等资料,认为恩梅开江断裂中-晚元古代为一条韧性剪切带,但在喜马拉雅期发生了脆性变形,表现为一条由多条脆性断层叠加于韧性剪切带的断裂带。断裂新构造活动期主要集中在上新世到更新世。全新世以来活动性较弱,对水电站工程建设影响微弱。     

矿液致裂作用对苗儿山矿田花岗岩型脉状铀矿床多期成矿的制约

运用矿液致裂理论与多种测试技术,详细研究了桂北苗儿山矿田花岗岩型脉状铀矿床矿脉的形态与内部结构,获知成矿时矿液的压力大于围岩的静压力,矿脉由矿液压裂作用形成。在此基础上讨论了矿液致裂对花岗岩型脉状铀矿床多期成矿的控制。     

多孔可变临界孔隙度模型及储层孔隙结构表征

碳酸盐岩、致密砂岩和页岩等储层具有孔隙类型多样、孔隙结构复杂和非均质性强等特征,属于典型的多重孔隙储层,孔隙结构表征是多重孔隙储层预测和流体识别的关键.现有的孔隙结构表征方法大多利用孔隙纵横比或者构建一种新参数来描述孔隙结构.岩石临界孔隙度模型是一种常用的岩石物理模型,具有一定的物理意义和地质含义.本文推导了岩石临界孔隙度与岩石孔隙结构(孔隙纵横比)之间的关系,进而利用极化(形状)因子建立临界孔隙度与弹性参数之间的关系,构建了能够包含多种孔隙类型的多孔可变临界孔隙度模型.利用多孔可变临界孔隙度模型由储层的弹性参数反演不同孔隙类型的体积含量.实验室测量数据和实际测井数据表明,多孔可变临界孔隙度模型能够适用于多重孔隙储层岩石物理建模和孔隙结构表征.     

评估MODIS的BRDF角度指数产品

应用地表观测的二向性反射数据集和多种MODIS数据产品,通过统计分析,对MODIS的二向性反射角度指数产品进行综合评估,结果表明:(1)MODIS角度指数包含了地表三维结构信息,有望用来反演地表的物理结构参数;(2)MODIS角度指数是内在的三维关系,各向异性因子(Anisotropic Factor:ANIF)和各向异性指数(Anisotropic Index:ANIX)高相关,建议去掉ANIF以精炼MODIS角度指数产品;(3)各向异性平整指数(Anisotropic FlatIndex:AFX)较好地指示了地表基本散射类型的变化,且具有较小的类内方差,对改善特定地表分类精度可能会更有用.     

Estimates of parameters of grain-size distribution from weight frequencies

When grains of a sediment sample are separated by sieving into a number of size classes, the weight of the grains belonging to a particular size-class is called the weight frequency of that class. That the weight frequencies cannot be used as simple frequencies for the calculation of the mean and standard deviation of size of grains is well known. A method is developed in this paper for estimating these two as well as a third parameter, named shape parameter, by minimizing a quadratic form that arises naturally as an analogue of the ² statistic. Two fully worked out numerical examples, with simulated data, are presented to illustrate the method. A computer program in FORTRAN language is also appended. Comparative study shows that the quicker conventional method used by geologists may produce reasonably good estimates of standard deviation when the sample size is large, but the estimates of mean may show large deviations.