地理信息标准研制的国内外进展及思考

通过对比分析国内外地理信息标准研制的进展,发现国内外标准化机构的工作重点均从地理数据标准化逐渐向地理信息服务标准化转变.在此基础上,从工作机制和标准研制两方面,思考了我国地理信息标准化近期应采取的对策.     

准噶尔盆地中部III 区块原油中25-降藿烷分布特征与成因意义

通过对准噶尔盆地中部Ш区块原油或油砂抽提物的饱和烃气相色谱-质谱分析,研究了原油或油砂抽提物中25-降藿烷的分布规律.结果表明,不同井区或同一口井不同深度(层位)的原油25-降藿烷的相对含量存在比较明显的差别,表明其所遭受的生物降解程度有所差异,沿构造带从南到北,同一油层中原油的生物降解程度增强,比如位于构造北部(构造部位相对较高)的永1井、永3井侏罗系原油25-降藿烷丰度较高,表明生物降解比较明显,而位于南部(构造低部位)的永6井白垩系和侏罗系油层中的原油均无明显的生物降解现象;同一口井随深度增大生物降解作用将弱,如永2井浅部白垩系油层的原油降解较严重,而深部西山窑组的原油降解作用则不明显.根据原油生物降解的特征,结合车-莫古隆起调整对研究区油气成藏的影响,讨论了原油生物降解差异分布的成因机制.     

空间索引与多尺度表达的一体化模型研究

在分析各种常用索引的基础上,依据各自的适用范围,提出了对点对象建立格网索引,对线、面对象建立改进四叉树索引的组合优化策略。设计的改进四叉树索引避免了传统四叉树的重复索引,提高了数据访问的效率。     

GIS在四川城市环境地质调查评价中的应用

将GIS应用于四川城市环境地质调查评价,建立一套完整的标准,指导全省21城市的数据库建设工作。在数据库的基础上利用MAPGIS二次开发平台,集成四川城市环境地质问题调查评价信息系统,供地方政府和各级管理机构使用。     

误差熵的估计问题研究

指出了具有复杂分布的随机量的总体熵的估计问题,首次给出了估计熵的最小截断误差限.推导了样本熵的近似估计公式,引入最优窗宽、全局最优窗宽的算法,首次解决了样本熵的估计值不惟一的问题.     

追忆李四光对防震减灾的贡献,以系统整体观指导防震应急

笔者在追忆李四光地震科学和防震减灾指导思想的基础上,提出了以系统整体观指导防震应急的新论点,包括:运用地壳运动整体观研究地震规律;应用地震预测整体观进行地震预测;划分活动性构造体系,研究构造活动性;加强综合监测,研究各种地震前兆和相关的自然变异的发展趋势;圈定地震风险区,制定防震应急预案等.并结合中国的实际情况进行了论述.     

Interactive 3-D computation of fault surfaces using level sets

Deformable implicit surfaces, implemented with level set methods, have demonstrated a great potential in the computational sciences for applications such as modeling, simulation, and segmentation. They allow implicit handling of complex topologies deformed by operations where large changes can occur without destroying the level set representation. The use of level set techniques for the computation and segmentation of plane-like and high positive curvature features is nontrivial. We present a technique for representing and extracting fault surfaces from 3-D seismic attribute data such that 2-manifolds can be interactively computed and segmented. We present our approach as an interactive workflow that generates highly accurate fault surfaces.     

A virtual voyage through 3D structures generated by chaotic mixing of magmas and numerical simulations: a new approach for understanding spatial and temporal complexity of magma dynamics

In this contribution, we present a virtual voyage through 3D structures generated by chaotic mixing of magmas and numerical simulations with the aim to highlight the power of 3D representations in the understanding of this geological phenomenon. In particular, samples of mixed juveniles from Salina island (Southern Italy) are reconstructed in 3D by serial lapping and digital montage and numerical simulations are performed by using a 3D chaotic dynamical system. Natural and simulated magma mixing structures are visualized by using several multimedia tools including animations and “virtual reality” models. It is shown that magma interaction processes can generate large spatial and temporal compositional heterogeneities in magmatic systems. The same topological structures are observed in both 3D reconstructed rock samples and chaotic numerical simulations, indicating that the mixing of magmas is governed by chaotic dynamics. The use of 3D multimedia models gives the opportunity to penetrate into magma mixing structures and to understand their significance in the context of magma dynamics. Such an approach is very powerful since multimedia tools can strongly capture the attention of the reader bringing him/her into an interactive and memorable geological experience. Electronic supplementary material  enclosed:     

北京市有机氯农药填图与风险评价

采用1个样/km2的密度、1个分析组合样/16km2的方法,对北京市784km2范围内的土壤、大气干湿沉降物、大气颗粒物中HCH、DDT的含量和空间分布特征进行有机氯农药填图.查明2000年北京市地表土壤HCH和DDT的平均含量分别为8.80±11.83ng/g、108.99±301.90ng/g.2006年大气干湿沉降物中HCH和DDT平均含量分别为10.09±9.60ng/g、12.99±13.51ng/g,HCH和DDT的年沉降通量分别为996.57±939.96g/a·km2、1291.53±1342.28g/a·km2.2006年大气颗粒物PM10和PM2.5中的HCH含量分别为0.294±0.205ng/m3和0.217±0.137ng/m3,DDT的平均含量分别为1.037±1.301ng/m3和0.522±0.773ng/m3,显著高于2002-2003年度大气颗粒物中HCH(PM100.01786ng/m3,PM250.01731ng/m3)和DDT(PM100.01672ng/m3,PM2.50.02353ng/m3)的含量,表明北京市或周边地区仍在使用含HCH和DDT化学成分的农药.以2000年北京地表土壤和2006年大气干湿沉降物中HCH和DDT的含量为基础,对2020年土壤中HCH和DDT的时空演变的预测显示,即使干湿沉降物中HCH和DDT的沉降通量每年以5%的速率递减,到2020年土壤中HCH和DDT的环境质量仍不能显著改善,而控制和削减北京及周边地区含HCH和DDT成分农药的使用将是改善北京地表土壤环境质量的关键措施.