Change Laws of Intensity of Moderate-Small Earthquakes (2.0≤Ms≤5.5)

The change laws of intensity of nearly 200 moderate-small earthquakes with Ms=2.0~5.5 occurring on the Chinese mainland since 1954 have been analyzed and are compared with that of moderately strong earthquakes(Ms≥5.0).The results show that there is quite obvious regionality in the statistical laws by both moderate-small earthquakes and moderately strong earthquakes:attenuation of intensity in Eastern China is slower than that in Western China and the ratio of the major axis to the minor axis of iso-seismal lines in Eastern China is smaller than that in Western China.The results also show that for a fixed magnitude the attenuation of intensity of moderate-small earthquakes is faster when intensity is higher than V and slower when intensity is lower than V-in comparison with that of moderately strong earthquakes.Furthermore,there also have been some differences in the aspects as intensity-magnitude relation between statistical laws of moderate-small earthquakes and moderately strong earthquakes.These di     

羌塘盆地胜利河海相油页岩地球化学特征及Re-Os定年

地球化学资料表明,羌塘盆地胜利河海相油页岩有机碳含量为15.05%～20.34%,平均为17.695%,灰分含量为55.23%,焦油含量为11.0%;干酪根类型为Ⅱ1或Ⅱ2型。利用Re-Os同位素对该油页岩层进行定年,得到的等时线年龄为101±24Ma。该等时线年龄比生物地层所获得的地层年龄年轻。     

北京天竺晚上新世以来植被演替与气候变迁

研究了北京天竺TZ01钻孔岩心孢粉样品239块，孢粉组合反映了北京天竺晚上新世以来(约3.580 Ma BP)植被演替和气候变迁大致经历了10个发展阶段：(1) 3.580～3.050 Ma BP：以针叶林植被为主，气候寒冷偏湿；(2) 3.050～2.555 Ma BP：植被为落叶阔叶和常绿阔叶混交林-草原类型，该阶段开始升温，但气候较为温暖湿润；(3)2.555～2.300 Ma BP：植被为温凉偏干的疏林草原，湿度开始下降；(4) 2.300～1770 Ma BP：植被类型仍为疏林草原，该阶段温度上升，但幅度并不大，湿度基本不变，气候温凉干爽；(5) 1.770～1.070 Ma BP：植被类型为针阔混交林-草原，气候温暖湿润；(6) 1.070～0.922 Ma BP：植被演替为较暖湿略干的针阔混交林-草原；(7)0.922～0.800 Ma BP：植被为较寒冷干燥的疏林草原，温度降低，降水减少；(8) 0.800～0.650 Ma BP：植被为温暖偏干的以松为主的疏林草原，温度有所上升，但湿度变化较小；(9)0.650～0.160 Ma BP：植被为温凉湿润的针阔叶混交林-草原；(10) 0.160 Ma BP至今：植被以针阔叶混交林-草原为主，前期气候冷湿，后期较为温暖湿润。     

Petrogenesis of the Pt–Pd mineralized Jinbaoshan ultramafic intrusion in the Permian Emeishan Large Igneous Province,SW China

The Jinbaoshan ultramafic intrusion is a sheet-like body with a thick wehrlite unit in the center and thin pyroxenite units at the margins. PGE are enriched in several disseminated sulfide zones in the intrusion. Olivine from the intrusion has low Fo and depleted Ni contents compared to olivine from coeval Emeishan picrites. Whole rock major and trace element concentrations suggest that the Jinbaoshan wehrlites originally contained <30% trapped liquid. The total amount of sulfide in the rocks exceeds that which could have been dissolved in the trapped liquid. The Jinbaoshan wehrlites are interpreted to represent residual assemblages formed by dissolution of plagioclase by passing magma. No clear evidence of crustal contamination is indicated by S, Nd and Os isotopes. We envision that sulfide saturation occurred at depth due to olivine and chromite crystallization. Immiscible sulfide droplets were transported to the Jinbaoshan conduit where they accumulated and reacted with magma successively passing through the conduit to achieve high PGE concentrations.     

土-地铁隧道动力相互作用的大型振动台试验——试验结果分析

在进行土-地铁隧道动力相互作用的大型振动台模型试验中,分别测出了模型地基的加速度反应、隧道结构的加速度反应、结构的侧向土压力反应和隧道结构的应变反应。本文首先对模型体系的加速度反应实测值进行整理,分析了模型地基的边界模拟效果、模型地基和隧道结构的加速度反应规律。其次,对模型隧道结构的应变实测结果进行了分析,给出了地铁区间隧道在水平向地震动作用下横截面的应变分布规律,分析了模型箱侧壁与地基土以及隧道结构与土体接触面上的动土压力实测结果及其反应的规律。最后,对试验中模型土的液化现象、地震裂缝和地下结构上浮等震害现象进行了描述。     

On the Performance Evaluation of Pan-Sharpening Techniques

The limitations of the currently existing pan-sharpening quality indices are analyzed: the absolute difference between pixel values, mean shifting, and dynamic range change is frequently used as spatial fidelity measurement, but they may not correlate well with the actual change of image content; and spectral angle is a widely used metric for spectral fidelity, but the spectral angle remains the same if two vectors are multiplied by two individual constants, which means the average spectral angle between two multispectal images is zero even if pixel vectors are multiplied by different constants. Therefore, it is important to evaluate the quality of a pan-sharpened image under a task of its practical use and to assess spectral fidelity in the context of an image. In this letter, three data analysis techniques in linear unmixing, detection, and classification are applied to evaluate spectral information within a spatial scene context. It is demonstrated that those old but simplest approaches, i.e., Brovey and multiplicative (or after straightforward adjustment) methods, can generally yield acceptable data analysis results. Thus, it is necessary to consider the tradeoff between computational complexity, actual improvement on application, and hardware implementation when developing a pan-sharpening method.     

长距离跨海高程基准传递方法及精度

大连市C级GPS控制网覆盖面积为1.7万km2.其中海域为4 700 km2,容有长山列岛的大小不等8个岛屿,8个网点分布在海岛,陆地与近海岛屿之间的距离为20-30 km;岛屿之间的距离为30-40 km;最大间距为120.5 km.本次研讨利用GPS定位技术结合重力资料所确定的小长山岛上网点高程与利用潮位观测法获得的相应网点高程比较,通过比较小长山GPS网点高程差值的方法研究长距离跨海高程基准传递可取的方法及精度.     

用HV谱比法推测银川市区沉积层基底分布特征

在缺乏其他资料的情况下,地脉动常常用做确定地震动对地表介质产生影响效应的简便手段。本文以银川市区为研究对象,根据地震勘探资料有目的的选取5条测线在银川市区进行地脉动观测,观测点共141个。用Nakamura提出的HV谱比法解析观测数据,在给定地下构造剪切波速度(VS)的基础上,由H/V比值曲线中的基本频率推测盆地深层地下构造。通过理论计算进一步验证了解析结果。结合前人地震勘探资料推测了银川市区脉动基本频率分布特征,并给出2D和3D银川市基底构造变化情况,对比分析表明,HV谱比法得到的脉动基本频率值可以反映银川盆地基底变化情况。     

Anisotropic reverse-time migration for tilted TI media

Seismic anisotropy in dipping shales results in imaging and positioning problems for underlying structures. We develop an anisotropic reverse‐time depth migration approach for P‐wave and SV‐wave seismic data in transversely isotropic (TI) media with a tilted axis of symmetry normal to bedding. Based on an accurate phase velocity formula and dispersion relationships for weak anisotropy, we derive the wave equation for P‐wave and SV‐wave propagation in tilted transversely isotropic (TTI) media. The accuracy of the P‐wave equation and the SV‐wave equation is analyzed and compared with other acoustic wave equations for TTI media. Using this analysis and the pseudo‐spectral method, we apply reverse‐time migration to numerical and physical‐model data. According to the comparison between the isotropic and anisotropic migration results, the anisotropic reverse‐time depth migration offers significant improvements in positioning and reflector continuity over those obtained using isotropic algorithms.     

《气象与环境科学》2007年总目次

阐述了利用VB和Fortran语言混合编程开发气象预报系统的两种方法,一种是利用VB的shell函数调用可执行文件法,另一种是利用VB调用Fortran生成的动态链接库法,并具体介绍了如何通过DLL实现VB 6.0和Fortran的接口,最终实现VB的可视化界面与Fortran强大数值计算能力相结合的新思路.