India-Eurasian collision vs. ocean-continent collision＊

Introduction Major tectonic activities occur in collisions zones between plates or intra-plate continental blocks. Therefore, it is significant to investigate collision processes. We know that orogenic and seismic belts in plate margins are closely relate…     

Evolution of cumulative Coulomb failure stress in northeastern Qinghai-Xizang （Tibetan） Plateau and its effect on large earthquake occurrence

We simulate accumulative Coulomb failure stress change in a layered Maxwell viscoelastic media in the north-eastern Qinghai-Xizang(Tibetan)Plateau since 1920.Lithospheric stress/strain evolution is assumed to be drivenby dislocations of large earthquakes(M≥7.0)and secular tectonic loading.The earthquake rupture parameters suchas the fault rupture length,width,and slip are either adopted from field investigations or estimated from their sta-tistic relationships with the earthquake magnitudes and seismic moments.Our study shows that among 20 largeearthquakes(M≥7.0)investigated,17 occurred in areas where the Coulomb failure stress change is positive,with atriggering rate of 85%.This study provides essential data for the intermediate to long-term likelihood estimation oflarge earthquakes in the northeastern Tibetan Plateau.     

An Intercomparison of Rules for Testing the Significance of Coupled Modes of Singular Value Decomposition Analysis

This paper clarifies the essence of the significance test of singular value decomposition analysis （SVD）, and investigates four rules for testing the significance of coupled modes of SVD, including parallel analysis, nonparametric bootstrap, random-phase test, and a new rule named modified parallel analysis. A numerical experiment is conducted to quantitatively compare the performance of the four rules in judging whether a coupled mode of SVD is significant as parameters such as the sample size, the number of grid points, and the signal-to-noise ratio vary.
The results show that the four rules perform better with lower ratio of the number of grid points to sample size. Modified parallel analysis and nonparametric bootstrap perform best to abandon the spurious coupled modes, but the latter is better than the former to retain the significant coupled modes when the sample size is not much larger than the number of grid points. Parallel analysis and random-phase test are robust to abandon the spurious coupled modes only when either （1） the observations at the grid points are spatially uncorrelated, or （2） the coupled signal is very strong for parallel analysis and is not weak for random-phase test. The reasons affecting the accuracy of the test rules are discussed.     

高分辨率探地雷达及实验研究

本文作者开发基于E5071B型矢量网络分析仪(VNA)的高分辨率探地雷达系统(LANRCS—GPR),该系统立足于频率域探地雷达系统的宽频带和适应性强的优点之上,充分发挥了矢量网络分析仪具有的超宽带、高精度测量等特性。该系统采用LAN方式进行系统联机控制方式,使系统组建成本低廉、易于扩展:本系统采用了计算效率高的F-K偏移方法作为实时成像方法。系统测试实验表明,该系统具有很高的探测分辨率,探测精度高,信号信噪比高,系统动态范围大,而且系统的操作灵活可靠,适应范围广,系统功能可扩展性强。该系统的研究开发为将来成品频域探地雷达系统的研发提供了理论、实验基础,同时也为电磁波传播研究及电磁探测研究搭建了一个采集数据精度高、信息量大、适应范围广、操作方便的实验平台。     

湿Q矢量释用技术及其在定量降水预报中的应用

新发展了一种湿Q矢量释用技术:利用松弛法迭代求解以非地转干Q矢量散度为强迫项的方程得到垂直运动场ω ₁, 然后由ω ₁计算湿Q矢量散度场, 接着再利用松弛法迭代求解以湿Q矢量散度场为强迫项的ω方程得到垂直运动ω ₂, 最后由ω ₂结合水汽条件进行降水量计算, 得到湿Q矢量释用降水场。结合一次典型的江淮梅雨锋暴雨过程研究表明, 湿Q矢量释用降水场对同期观测降水场水平分布特征、极端降水强度都具有一定的反映能力, 反映出湿Q矢量释用技术具备实际应用的可行性和一定合理性。将此释用技术应用于华东区域数值预报模式 (基于MM5 V3.6而建立, 以下简称MM5) 产品, 得到湿Q矢量释用定量降水预报 (QPF) 场, 其独立于模式本身输出的QPF场, 但与模式QPF场具有相同的时空分辨率。针对2004年6—8月汛期华东地区一次梅雨锋降水过程和一次登陆台风降水过程, 结合实况雨量资料, 比较分析了湿Q矢量释用QPF场和MM5模式QPF场对实际观测降水场的反映能力, 结果表明, 前者对有无降水、10.0 mm/24 h以上明显降水的反映能力明显优于后者。进一步进行预报统计检验表明, 湿Q矢量释用预报有无降水、小雨及10.0 mm/24 h以上降水的TS评分、正确率都明显高于MM5模式, 而漏报率、空报率则是前者明显低于后者。这也充分反映出湿Q矢量释用技术应用于QPF研究的有效性。最后, 探讨了数值预报产品释用技术对数值预报模式性能的依赖性, 并指出未来对湿Q矢量释用技术进一步改进的方向及其广泛应用前景。     

Receiver Functions from Autoregressive Deconvolution

Summary Receiver functions can be estimated by minimizing the square errors of Wiener filter in time-domain or spectrum division in frequency domain. To avoid the direct calculation of auto-correlation and cross-correlation coefficients in Toeplitz equation or of auto-spectrum and cross-spectrum in spectrum division equation as well as empirically choosing a damping parameter, autoregressive deconvolution is presented to isolate receiver function from three-component teleseismic P waveforms. The vertical component of teleseismic P waveform is modeled by an autoregressive model, which can be forward and backward, predicted respectively. The optimum length of the autoregressive model is determined by the Akaike criterion. By minimizing the square errors of forward and backward predicting filters, autoregressive filter coefficients can be recursively solved, and receiver function is also estimated in the similar procedure. Both synthetic and real data tests show that autoregressive deconvolution is an effective method to isolate receiver function from teleseismic P waveforms in time-domain.     

交互式数据语言在气象数据可视化中的应用

科学计算可视化是20世纪80年代后期随着计算机图形学应用的拓广而发展起来的一个新的研究分支，受其推动，数字信息的可视化成为20世纪90年代研究的前缘。随着“数字地球”、“数字城市”、“数字油田”等概念的提出，气象工作者迫切需要更加精确地了解各种气象数据和地形实体。而对于这些复杂的数据资料，目前人们已不能满足于等线图那样的平面描述，更需要建立三维图像，用更接近实际的方式去描述它，从各个不同角度观察它，三维可视化就是实现以上目标的有效手段。实体三维可视化技术是描绘和理解三维实体的一种重要计算机技术，它可以帮助使用者快速、准确理解和描述三维实体，并能协助快速选定感兴趣的目标，为分析、理解数据提供了有利工具。     

合浦绒螯蟹生长和生态特性

为保护和开发合浦绒螯蟹资源,通过生态调查和养殖试验,研究了该蟹的生长和生态特征,结果表明该蟹在淡水中生长,在盐度8～25的海水中繁殖;其生活史包括卵、蚤状幼体、大眼幼体、幼蟹和成蟹5个阶段.各阶段的生长和生态特征各不相同.规格较大的蟹其绝对生长值也大,但相对生长率则较小;相反,规格较小的蟹其绝对生长值较小,但相对生长率则较大.合浦绒螯蟹交配的适宜水温是1 5～20℃,盐度8～25;蚤状幼体生长的适宜水温为20～25℃,盐度8～25;大眼幼体已趋于淡水生活,其生长适温18～28℃;幼蟹和成蟹在淡水中生活,适温是20～30℃.资源调查和养殖试验结果表明合浦绒螯蟹的生长速度较快,一年内可长成,开展人工养殖是可行的.     

Geochemistry of ore-forming fluids and geological significance

The Kuoerzhenkuola gold field (including the Kuoerzhenkuola and the Buerkesidai gold deposits) is the most important one in the Sawuer gold belt, northern Xinjiang, China. Isotopic studies including D, O, He, C, S, Pb and Sr reveal that the ore-forming fluids of the Kuoerzhenkuola and the Buerkesidai deposits shared the same source: the water of ore fluids was magmatic water and minor meteoric water; the mineralizers and ore materials derived mainly from mantle beneath the island arc, and partially from crust. The ore-forming fluids of two deposits are a mixture of mantle-derived fluids incorporated by crust-derived fluid, and meteoric water. Based on these results, combined with the consideration of the tectonic setting and geological features, we suggest that the two gold deposits in the Kuoerzhenkuola gold field, Sawur gold belt share the same genesis, and are volcanogenic hydrothermal gold deposits occurring in the same caldera.     

Isolation and characteristics of one marine psychrotrophic cellulase-generating bacterium Ar/w/b/75°/10/5 from Chuckchi Sea,Arctic

Microorganisms living in polar zones play an important part as the potential source of organic activity materials with low temperature characteristics in the bio-technological applications. A psychrotrophic bacterium (strain Ar/w/b/75°/10/5) , producing cellulose at low temperatures during late-exponential and early-stationary phases of cell growth, was isolated from sea ice-covered surface water in Chuckchi Sea, Arctic. This bacterium, with rod cells, was Gram-negative, slightly halophilic. Colony growing on agar plate was in black. Optimum growth temperature was 15℃. No cell growth was observed at 351 or above. Optimum salt concentration for cell growth was between 2 and 3 % of sodium chloride in media. Maximal cellulase activity was detected at a temperature of 35℃ and pH8. Cellulase was irreversibly inactivated when incubated at 55℃ within 30 min. Enzyme can be kept stable at the temperature no higher than 25℃. Of special interest was that this bacterium produced various extracellular enzymes i