浅谈调整测绘产业的发展方向

本文通过对目前测绘市场的划分和简单分析 ,阐述了在当今市场经济条件下 ,测绘产业应适当调整发展方向 ,积极参与市场竞争的途径。     

M51 revisited: A genetic algorithm approach of its interaction history

Detailed models of observed interacting galaxies suffer from the extended parameter space. Here, we present results from our code MINGA which couples an evolutionary optimization strategy (a genetic algorithm) with a fast N-body method. MINGA allows for an automatic search of the optimal region(s) in parameter space within a few hours to a few days of CPU time on a modern PC by investigating of the order of 10⁵ models. We demonstrate its applicability by modelling the HI intensity and velocity maps of the interacting system M51 and NGC 5195. We get a good fit for the HI intensity map and we can reproduce the counter-rotation feature of the HI arm. Our result corroborates the results of Salo and Laurikainen (2000) who favour a model with multiple passages through M51's disk. This revised version was published online in August 2006 with corrections to the Cover Date.     

Distribution of Fe2+ and Fe3+ and next-nearest neighbour effects in natural chromites: comparison between results of QSD and Lorentzian doublet analysis

The Mössbauer spectra of one chromite at 298 K and one chromite at 298, 200, 170, 140 and 90 K have been analyzed in this study. A Voigt-based quadrupole splitting distribution (QSD) method was used to analyze the spectra. The tetrahedral site Fe²⁺ and the octahedral site Fe³⁺ quadrupole splitting distributions (QSDs) were obtained from the Mössbauer spectra of chromites, and the multiple tetrahedral site Fe²⁺ Gaussian QSD components and the large widths σ _Δ of the Gaussian QSD components of the tetrahedral site Fe²⁺ QSDs for chromites were attributed to next-nearest neighbor effects. In addition, temperature dependences of the isomer shift and the quadrupole splitting were presented and discussed. Comparisons between the Mössbauer parameters for thickness-corrected folded spectra and raw-folded spectra of chromites were made, and the results show that the two sets of the Mössbauer parameters and ratios of ferric to total iron as well as χ² are very close to each other. This is because of the small absorber thickness of chromites in this study. Comparisons between the Mössbauer parameters of chromites obtained using the Voigt-based QSD method and a Lorentzian doublet method were also made. The results show that there are some differences between the two sets of the Mössbauer parameters and ratios of ferric to total iron, but not significant. However, much larger χ² were obtained when the Lorentzian doublet method was used to fit the spectra of chromites. This indicates that the Voigt-based QSD method is more adequate to analyze the Mössbauer spectra of chromites from the point of view of statistics.     

丽江7.0级地震前形变场动态演化与孕震信息提取研究

本文用分段速率整体动态平差法，处理了滇西水准监测网８０年代以来的水准复测资料，并进行了形变速率多面函数拟合和垂直形变场信息分离。研究了１９９６年２月３日发生于滇西水准监测网北部的丽江７０级地震前，形变场动态演化和信息分离得到的垂直形变剪切变形、扩张变形、体积变化及准加速度等信息指标分布变化特征。结果表明：８０年代中前期，在滇西的丽江、永胜及其附近地区出现的大规模形变速率高梯度带和信息指标高值分布所反映的剧烈垂直差异运动，是丽江７０级地震前１０余年孕震应变能开始快速积累的显示；而１９８５～１９９２年形变场趋势转折与垂直差异运动显著减弱，可能意味着孕震能量积累到一定程度后，孕震区处于相对闭锁阶段。在此基础上，结合丽江７０级地震前区域地震活动分析和不同地区强震孕震形变对比，进一步研究了强震前形变场非均匀态特征和孕震信息的识别提取，得出了一些用大地形变进行强震中期预测的有益结果。     

丽江7.0级地震丽江县城房屋震害分析

本简述丽江７．０级地震造成的丽江县城钢筋砼框架、砖混结构和单层空旷房屋的震害，研究了房屋的特征，对震害的原因作了初步分析。     

丽江7.0级地震的烈度分布

本综合丽江地震宏观考察资料、系统介绍了整个震区和丽江县城（大研镇）的烈度分布及各烈度区的震害特征，并对一些主要烈度异常点（区）产生的原因进行了初步分析。     

丽江7.0级地震震源环境及其破裂过程讨论

本通过对丽江Ｍｓ７．０地震发生环境和破裂过程的分析讨论，得到以下认识：丽江地震发生在滇西北裂陷区北部块体内，这是一个由三组深断裂切割包围的三角形断块，断块内发育有裂陷盆地（大具－丽江裂陷盆地）；该区除了水平应力作用外，还有很强的来自地幔物质上隆引起的垂直应力作用；主余震分布在地壳一个由相对低速区包围的高速区内。地壳介质结构横向非均匀性－地壳高速块体的存在，可能是丽江地震震源成核的重要成因。丽江７     

武定6.5级地震序列震源机制

由地震Ｐ波初动符号资料，求解得到１９９５年１０月２４日武定６．５级地震序主震及２１外强余震的震源机制解。主震的两个节面走向分别为北西西向，倾向ＮＮＥ，倾角７０°；另一个节面走向为北北东，倾向Ｗ，倾角７７°；等效释放应力场主压力力方位为３２４°，仰角２４°。表明与区域应力场基本一致的主要震震源应力场及发震断裂控制着整个序列的地震活动。     

对2001年11月14日新疆-青海交界8.1级大震预测的反思

20 0 1年 1 1月 1 4日在新疆 -青海交界地区发生了 8.1级大震。震中为 90 .9°E,3 6.2°N。本文对这次大震的粗略预测作了回顾 ,并讨论了有关 8级大震的某些问题     

Calculation of the parameters of georesistivi－ty anisotropy and case history of earthquake precursors

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