在MapInfo中实现区域对象样点布设功能

随着GIS在森林资源管理中应用的不断深入，在GIS系统中实现林业专业抽样设计功能是非常必要的。本文使用MapBasic鳊程语言实现三种样点布设功能。操作时，用鼠标点击欲布样点区域，在弹出对话框中作出回答，就能得到样点布设图和样点坐标表。     

GIS支持下的全国广播电视信息管理系统的建设

介绍了GIS支持下的与专业信息充分结合的 ,为领导和专业技术人员提供决策支持等方面的实例。从技术和应用角度论述了服务于全国广播、电视信息管理和决策的“GIS支持下的全国广播电视覆盖信息管理系统”。对构成系统的数据组成、数据库结构、主要功能模块、应用效果等情况进行了系统论述     

基于先验知识的GIS路径寻优算法

针对地理信息系统中特定的两点路径寻优问题,提出了一种基于先验知识的快速搜索算法。该算法模拟人脑寻找路径的思维过程,首先针对实际问题建立先验知识库,在路径搜索过程中,利用知识库中的信息剪去不可能的搜索路径,构造出简化的查询树,从而大大提高最优路径的搜索速度。     

利用信噪比削弱GPS多路径效应的研究

由于多路径误差的非时空相关性,使其成为双差模型中较难解除的误差源。本文利用观测值的信噪比对观测值质量进行评价,通过降低受多路径效应影响的观测值的权重,从而达到削减多路径误差的目的。最后通过实验数据解算结果的重复性验证了此方法的有效性和可靠性。     

地图投影的最小二乘二元多项式拟合的误差估计

探讨了在地图投影的最小二乘二元多项式拟合中参考点的分布对拟合误差的影响,提出了一种基于矩阵的秩亏的方法来判断参考点是否在指定次数的二元多项式空间的代数曲线上,并导出在极小范数最小二乘意义下的拟合多项式的误差估计式,公式表明拟合误差和参考点的最小二乘误差无关。     

叶面积指数(LAI)的遥感定量方法综述

总结了当前遥感定量研究叶面积指数(LAI)的两种主要方法:统计模型法和光学模型法,阐述了各自的机理和研究进展,在此基础上,讨论了两种方法的优缺点及未来的发展趋势。     

长江三角洲长江以北地区全新世以来人地关系的环境考古研究

通过长江三角洲长江以北地区高邮龙虬庄和海安青墩两个新石器时代考古遗址剖面粒度、磁化率、孢粉以及年代学测定，较为全面地分析了该区全新世以来生态环境变化与人类文明兴衰的相互关系，研究结果表明：在有人类活动以前，该区距离海洋较远，但受海面变化影响强烈。此后，气候向暖湿方向发展，7000—6000间的大西洋温暖湿润气候以及3700aB．P．左右期间，该区气候适宜，人类文明在这样的适宜气侯条件下得到长足发展。值得注意的是，海安青墩遗址剖面中出现厚达1m多的自然沉积地层，粒度分析以及孢粉分析表明，这一自然沉积地层是4000aB．P．以来的海侵事件所致，正是这次海侵事件，使研究区人类文明得以衰落。     

高原交通干线对土地利用和景观格局的影响——以兰州至格尔木段为例

运用景观生态学方法和Arc/Info软件，研究1995年至2000年兰州至格尔木铁路沿线的区域土地利用和景观格局变化，分析交通干线（公路和铁路）的影响程度与范围。主要结果如下：（1）东线土地利用和景观格局没有发生显著变化，西线土地利用和景观格局变化较大；（2）东线缓冲带土地利用程度综合指数没有显著变化，西线缓冲带土地利用程度综合指数明显升高。缓冲带综合土地利用动态度的变化反映了交通干线的轴向影响规律；兰州至西宁铁路对土地利用变化的显著影响范围是5km，青藏铁路对土地利用变化的显著影响范围是7km；（3）9个城市缓冲带的土地利用变化分析表明：城市扩展主要发生在1km缓冲带内。     

应用RMi法估算岩体变形模量

RMR法与Q法是国内外八、九十年代岩体质量和参数估算的常用方法,然而RMR法和Q法对质量较差的岩体不太实用,而RMi法是一种既适用于软岩又适用于硬岩的岩体质量评价和参数估算方法。本文在介绍RMi法基本原理的基础上,对贵州省鱼简河水库坝基岩体变形模量进行确定。     

Continental subduction and exhumation of UHP rocks. Structural and geochronological insights from the Dabieshan (East China)

In the Dabieshan, the available models for exhumation of ultrahigh-pressure (UHP) rocks are poorly constrained by structural data. A comprehensive structural and kinematic map and a general cross-section of the Dabieshan including its foreland fold belt and the Northern Dabieshan Domain (Foziling and Luzenguang groups) are presented here. South Dabieshan consists from bottom to top of stacked allochtons: (1) an amphibolite facies gneissic unit, devoid of UHP rocks, interpreted here as the relative autochton; (2) an UHP allochton; (3) a HP rock unit (Susong group) mostly retrogressed into greenschist facies micaschists; (4) a weakly metamorphosed Proterozoic slate and sandstone unit; and (5) an unmetamorphosed Cambrian to Early Triassic sedimentary sequence unconformably covered by Jurassic sandstone. All these units exhibit a polyphase ductile deformation characterized by (i) a NW–SE lineation with a top-to-the-NW shearing, and (ii) a southward refolding of early ductile fabrics.

The Central Dabieshan is a 100-km scale migmatitic dome. Newly discovered eclogite xenoliths in a Cretaceous granitoid dated at 102 Ma by the U–Pb method on titanite demonstrate that migmatization post-dates HP–UHP metamorphism. Ductile faults formed in the subsolidus state coeval to migmatization allow us to characterize the structural pattern of doming. Along the dome margins, migmatite is gneissified under post-solidus conditions and mylonitic–ultramylonitic fabrics commonly develop. The north and west boundaries of the Central Dabieshan metamorphics, i.e. the Xiaotian–Mozitan and Macheng faults, are ductile normal faults formed before Late Jurassic–Early Cretaceous. A Cretaceous reworking is recorded by synkinematic plutons.

North of the Xiaotian–Mozitan fault, the North Dabieshan Domain consists of metasediments and orthogneiss (Foziling and Luzenguang groups) metamorphosed under greenschist to amphibolite facies which never experienced UHP metamorphism. A rare N–S-trending lineation with top-to-the-south shearing is dated at 260 Ma by the ⁴⁰Ar/³⁹Ar method on muscovite. This early structure related to compressional tectonics is reworked by top-to-the-north extensional shear bands.

The main deformation of the Dabieshan consists of a NW–SE-stretching lineation which wraps around the migmatitic dome but exhibits a consistently top-to-the-NW sense of shear. The Central Dabieshan is interpreted as an extensional migmatitic dome bounded by an arched, top-to-the-NW, detachment fault. This structure may account for a part of the UHP rock exhumation. However, the abundance of amphibolite restites in the Central Dabieshan migmatites and the scarcity of eclogites (found only in a few places) argue for an early stage of exhumation and retrogression of UHP rocks before migmatization. This event is coeval to the N–S extensional structures described in the North Dabieshan Domain. Recent radiometric dates suggest that early exhumation and subsequent migmatization occurred in Triassic–Liassic times. The main foliation is deformed by north-verging recumbent folds coeval to the south-verging folds of the South Dabieshan Domain. An intense Cretaceous magmatism accounts for thermal resetting of most of the ⁴⁰Ar/³⁹Ar dates.

A lithosphere-scale exhumation model, involving continental subduction, synconvergence extension with inversion of southward thrusts into NW-ward normal faults and crustal melting is presented.