Systematic Analysis Method of Shear-Wave Splitting:SAM Software System

In order to make a more effective use of the data from regional digital seismograph networks and to promote the study on shear wave splitting and its application to earthquake stress-forecasting, SAM software system, i.e., the software on systematic analysis method of shear wave splitting has been developed. This paper introduces the design aims, system structure, function and characteristics about the SAM software system and shows some graphical interfaces of data input and result output. Lastly, it discusses preliminarily the study of shear wave splitting and its application to earthquake forecasting.

Variational characteristics of shear-wave splitting on the 2001 Shidian earthquakes in Yunnan, China

In 2001 three earthquakes occurred in Shidian in Yunnan Province, which were the MS=5.2 on April 10, the MS=5.9 on April 12 and the MS=5.3 on June 8. Based on the data from the station Baoshan of Yunnan Telemetry Digital Seismograph Network, the variational characteristics of shear-wave splitting on these series of strong earthquakes has been studied by using the systematic analysis method (SAM) of shear-wave splitting. The result shows the time delays of shear-wave splitting basically increase with earthquake activity intensifying. However the time delays abruptly decrease immediately before strong aftershocks. It accords with the stress relaxation before earthquakes, which was found recently in study on shear-wave splitting. The result suggests it is significant for reducing the harm degree of earthquakes to develop the stress-forecasting on earthquake in strong active tectonic zones and economic developed regions or big cities under the danger of strong earthquakes.

Statistical analysis of fracture properties based on particle swarm optimization and Pearson correlation coefficient method

Prediction of reservoir fracture is the key to explore fracture-type reservoir. When a shear-wave propagates in anisotropic media containing fracture,it splits into two polarized shear waves: fast shear wave and slow shear wave. The polarization and time delay of the fast and slow shear wave can be used to predict the azimuth and density of fracture. The current identification method of fracture azimuth and fracture density is cross-correlation method. It is assumed that fast and slow shear waves were symmetrical wavelets after completely separating,and use the most similar characteristics of wavelets to identify fracture azimuth and density,but in the experiment the identification is poor in accuracy. Pearson correlation coefficient method is one of the methods for separating the fast wave and slow wave. This method is faster in calculating speed and better in noise immunity and resolution compared with the traditional cross-correlation method. Pearson correlation coefficient method is a non-linear problem,particle swarm optimization( PSO) is a good nonlinear global optimization method which converges fast and is easy to implement. In this study,PSO is combined with the Pearson correlation coefficient method to achieve identifying fracture property and improve the computational efficiency.

下颌升支矢状劈开不同截骨术矫治下颌前突的对比分析

目的 探讨改良和经典下颌升支矢状劈开截骨术在矫治下颌前突方面的适应证及优缺点。方法 1997年1月～2005年1月，采用下颌升支矢状劈开截骨术矫正真性下颌前突及下颌前突合并其他部位畸形患者95例，男34例，女61例。年龄15～44岁，平均21．3岁。单纯下颌前突53例，下颌前突合并偏颌28例，上颌后缩11例，大舌2例，双侧颧骨突出1例。X线头影测量：蝶鞍点-鼻根点-上齿槽座点角（sella—nasion—A point，SNA）80～83°，蝶鞍点-鼻根点-下齿槽座点角（sella—nasion—B point，SNB）80～84°，上齿槽座点-鼻根点-下齿槽座点角（Apoint—nasion—B point，ANB）-3～1°。采用改良术式43例，经典术式52例。结果 患者术后面型及咬黯关系均得到明显改善。经典术式组患者术后单侧或双侧下唇区感觉障碍9例，劈骨时单侧下颌升支意外骨折1例，严重出血1例，术后切口感染1例，畸形轻度复发3例。改良术式组患者术后下唇区感觉障碍2例，畸形轻度复发1例，无颌骨意外骨折、严重出血和术后感染等并发症发生。随访3个月～7年，复查X线并进行头影测量：SNA角81～83°，SNB角78～81°，ANB角1～4°。结论 改良术式是下颌前突尤其是严重前突和伴有偏颌患者升支矢状劈开旋转、后退比较理想的一种手术方式，而对轻度至中度下颌前突患者则既可应用改良术式也可应用经典术式。

转换波处理关键技术应用及效果

GeoEast处理系统提供了丰富的多波资料处理技术,针对实际转换波资料处理过程中静校正、纵横波匹配、转换波速度建模、快慢横波时差提取的难点,应用转换波综合静校正技术大幅改善了转换波成像效果,利用井控纵波和转换波精细层位匹配技术获取了纵横波速度比,实现了纵横波层位的精确匹配,并通过转换波四参数叠前时间偏移速度建模技术得到合理、准确的转换波偏移参数场,最后使用横波分裂分析与校正技术进一步增强了转换波叠前时间偏移成像效果。应用结果表明,GeoEast多波处理技术能够满足转换波处理过程中的关键技术需求,通过纵横波资料相结合得到更丰富的转换波信息。

Hopkinson杆试验试件中应力状态近似分析与惯性修正

在Ｈｏｐｋｉｎｓｏｎ杆动态试验，特别是Ｈｏｐｋｉｎｓｏｎ拉杆试验中，由于试件尺寸长，惯性效应导致测试失真问题是人们关注的重要问题．本文对该问题进行了分析，发展了Ｇｏｒｈａｍ惯性修正模型，推导出一种新的惯性修正公式，该公式考虑了试件的径向和轴向惯性，变形率及试件端面效应，特别是考虑了惯性对试件内部速度场不均匀性的影响．计算分析表明，本公式对ＳＨＴＢ试件中惯性效应的修正量的计算值比Ｇｏｒｈａｍ模型的相应值要大４０％～５０％，虽然修正量的绝对值并不大．

基于小波相关性分析的双基线InSAR大气效应校正

针对InSAR在重复轨道模式下的地形测绘精度受到大气效应制约这一问题,提出了一种基于小波相关性分析探测双基线InSAR干涉对间的地形误差相位,从而间接校正大气效应的轻量级方法。该方法克服了已有大气效应校正方法依赖外部水汽数据或数据量需求大的局限性。在校正大气效应之前,为保证地形误差相位的唯一相似性,需要去除其他任何相同或相似的相位分量。选取了不同气候、地形条件下的洛杉矶地区和湖南中部地区作为典型实验区验证算法的有效性,并利用ALOS-1 PALSAR数据进行了实验。实验结果表明:算法在沿海水汽含量变化剧烈和内陆地形崎岖多变的区域都能稳定地校正大气效应,使得生成数字高程模型(DEM)的精度最高能提高53.4%和45.0%。其中,在沿海的洛杉矶实验区与基于GACOS产品的大气校正方法对比,精度提高了49.7%。