基于反向射线与顶点退化判断点在多边形内外的算法及应用

利用射线法判断点在多边形内外的方法简单易用,但是对于交点中含有顶点的情况,使用这种方法将产生奇异性,大大降低判断的准确性。鉴于这种情况,通过对已有的判断点在多边形内外算法的分析与研究,提出了基于反向射线和顶点退化处理相结合判断点在多边形内外的算法,并给出了具体的程序设计以及将该算法推广到了复杂多边形的情况。同时,将该算法应用于某市基础地理信息系统数据预编辑中,结果表明,判断准确率大大提高。     

中国假木贼属(Anabasis)的地理分布及潜在分布区预测

基于最大熵模型（MaxEnt）和地理信息系统,结合中国假木贼属（Anabasis）7个种的地理分布记录及19个环境因子,预测这7个种的潜在分布区及该属的分布中心,并分析其主导环境因子。采用受试者工作特征曲线下面积作为模型预测准确度的衡量指标,刀切法用于评估各环境因子在决定潜在分布区时的贡献量。结果显示：（1）白垩假木贼（A.cretacea）、高枝假木贼（A.elatior）、毛足假木贼（A.eriopoda）、无叶假木贼（A.aphylla）、盐生假木贼（A.salsa）和展枝假木贼（A.truncata）的潜在适生区集中在新疆北部、天山南麓及塔里木盆地西侧,短叶假木贼（A.brevifolia）的潜在适生区在新疆、甘肃、宁夏和内蒙古的部分地区。（2）中国假木贼属的分布中心在新疆准噶尔盆地、天山南麓、塔里木盆地西侧及甘肃西北部的河西走廊。（3）在19个环境因子中,对中国假木贼属这7个种分布区预测贡献量较大的生态因子是年平均气温、最湿月降水量、最干季度平均温度、平均降水量、最冷季度降水量、年均温变化范围和最湿季度降水量。     

Spatial ground motion effect on relative displacement of adjacent building structures

This paper analyses earthquake ground motion spatial variation effects on relative linear elastic response of adjacent building structures. It studies the relative importance of ground motion spatial variations and dynamic characteristics of adjacent structures in causing relative responses. Random vibration method is used in the study. It is found that, besides ground-acceleration-induced dynamic responses, quasi-static responses induced by spatially varying ground displacements also contribute significantly to the relative structural responses. The effects of spatial ground motions are very pronounced to the relative displacements of adjacent low-rise structures, and to those of high-rise adjacent structures with similar vibration characteristics. The effect of vibration properties of adjacent structures are, however, more significant to those of high-rise adjacent structures if they poses noticeably different vibration periods. Copyright © 1999 John Wiley & Sons, Ltd.     

多孔介质中两相可压缩可混溶驱动的GALERKIN方法

多孔介质中两相可压缩可混溶驱动问题由一对耦合的非线性方程来描述.Douglas在忽略弥散效应的情况下,讨论了该方程的半离散Galerkin求解方法,并得到了解的最优的L2模误差估计.文章讨论了在考虑弥散效应的情况下该方程的半离散Galerkin方法,并得到了饱和度方程解的最优L2模误差估计.     

联合IHS 变换和MAP 估计的遥感图像融合

为了提高多光谱图像和全色图像的融合质量, 提出一种基于推广的IHS(Generalized Intensity-Hue-Saturation, GIHS)变换与最大后验概率MAP(Maximum a Posteriori)相结合的遥感图像融合算法。该算法首先经过GIHS 变换, 由多光谱图像得到强度分量; 其次针对强度分量和全色图像, 通过MAP 构建高分辨率图像的成像模型, 采用最速下 降优化算法得到富含光谱信息的高分辨率全色图像; 进而依据GIHS 变换得到融合图像。实验中分别以IKONOS 卫 星、Quickbird 卫星的多光谱图像和全色图像为例, 进行融合算法验证, 并与GIHS 融合算法、传统的小波变换融合 算法、小波变换结合IHS 变换的融合算法等进行比较分析, 实验表明, 新的融合方法具有更好的融合效果。     

基于OpenGL城市大规模管网三维建模

城市管网是城市建设的重要组成部分。本文讨论了基于OpenGL的大规模城市管网三维建模技术,从介绍世界坐标系和局部坐标系的转换关系出发,重点介绍了管网的直线部分建模和管网衔接处的建模,提出了一种基于顶点混合技术来绘制管网衔接处的新算法,该算法方便高效,能产生逼真的效果,并给出了加快三维显示速度的方法,实现了城市管网的大规模实时建模。     

Ground movements caused by deep underground mining in Guan-Zhuang iron mine,Luzhong, China

It is difficult to calculate the accurate ground movement due to deep underground mining because of the complexity of the geotechnical environment. Guan-Zhuang iron mine is a pillarless sublevel caving mine operated by Luzhong Metallurgical Mining Company, south-east of Jinan, PR China. It mines the Zhangjiawa Seam at a depth of approximately 520 m. Although the towers are outside the conventional ‘angle of draw’ subsidence influence criteria, and have seen only negligible vertical displacement as a result of deep mining, there has been widespread evidence of regional horizontal displacement of the land surface, large distances away from the mining area. Possible explanations of these displacements include one or a combination of mechanisms such as pre-mining stress relaxation, regional joint patterns, soft rock strata, displacement toward active goaf areas. Luzhong Metallurgical Mining Company have been making precise measurements of distances near the shaft towers in the Guan-Zhuang iron mine since 2003. The results show horizontal displacements of up to 96 mm occur even when underground mining is about 0.8 km from the survey displacements. From an analysis of these and other survey results it is concluded that mining effects extend a long way from deep mining. The results also show that ground horizontal displacements are typically at least as great as the vertical component, that the maximum horizontal displacement occurs soon after undermining.     

多层次移位原则的道路与建筑物空间冲突处理

本文在分析传统道路与建筑物空间冲突算法的基础上,借鉴其优点,从保持建筑物间的整体空间布局特征,以及模拟人工移位的处理方法角度出发,提出根据区域密集程度的不同,划分为稀疏区、密集区、高密集区三个等级区域,并制定相应的多层次移位处理原则,然后,根据道路与建筑物的邻近程度,将建筑物分为多等级的移位层,对移位层内的冲突进一步细分;据此,依据移位层的邻近程度,将多层次处理原则贯穿于要素冲突外力的计算、外力的聚合以及其移位算法的确定中,分别对道路与建筑物的冲突、建筑物之间的冲突分别进行处理。     

钢筋混凝土框架结构直接基于位移的抗震设计

直接基于位移的抗震设计方法是对基于力的抗震设计方法的重大改进。按此方法进行设计时,需要解决的关键问题是确定结构的目标位移和相应的侧移模式。提出用框架梁节点截面屈服时的位移作为目标位移,并推导了层间屈服位移的计算公式;然后用结构近似的第一振型曲线作勾其侧移模式,对层间屈服位移进行修正。算例表明,本方法计算结果合理。