潮汐形变资料中地震前兆信息的识别与提取   总被引：30，自引：17，他引：13  

张燕  吴云  刘永启  褚永海  施顺英 《大地测量与地球动力学》2003,23(4):34-39

将小波变换的多分辨率分析引入潮汐形变资料处理中，对近年来云南地区的3次强震前的潮汐形变观测资料进行了处理与分析，发现在地震前2～5个月，震中附近的形变台站都接收到一个频段相同的异常信号，且它们之间是相关的，相关系数达80％以上，由此可以确定信号是由同一个源发出来的。出现在多个台站的相同频段的异常信号很可能就是我们想要得到的地震前兆信息。  相似文献   

Effect of animal orientation on acoustic estimates of zooplanktonproperties     

Warren  J.D. Stanton  T.K. McGehee  D.E. Dezhang Chu 《Oceanic Engineering, IEEE Journal of》2002,27(1):130-138

It is well known that the behavior of zooplankton and, in particular, their orientation distribution dramatically affects the level of backscattered acoustic energy. As a result, interpretation of acoustic survey data in the ocean is subject to error. In order to quantify these effects, laboratory data from two important classes of animals were collected. The data involved broad-band (350-650 kHz) acoustic signals insonifying individual animals whose orientation was varied over the range 0°-360° in 1° increments. The animals were from two major anatomical groups: fluid-like (decapod shrimp; Palaemonetes vulgaris) and elastic-shelled (periwinkles; Littorina littorea). The data were analyzed both in the time domain (with pulse compression processing) and the frequency domain. Averages of the laboratory data over different orientation distributions illustrate the variability in average target strength that can be expected in the ocean environment. The average target strength of the shrimp varied by 3 dB when averaged over orientation distributions centered around broadside and end-on incidence. In addition, size estimates from pulse compression processing of the broad-band echoes were made for various orientation distributions for both the shrimp and periwinkles. These results show the necessity of animal orientation information for the proper interpretation of acoustic backscatter data  相似文献   

Submicron polyphase inclusions in garnet from the Tananao Metamorphic Complex, Taiwan: a key to unravelling otherwise unrecognized metamorphic events     

S. L. Hwang  T. F. Yui  H. T. Chu  P. Shen 《Journal of Metamorphic Geology》2001,19(5):601-607

Kyanite and staurolite occur in the Tananao Metamorphic Complex as submicron inclusions in almandine‐rich garnet from a metamorphosed palaeosol weathering horizon, near Hoping, eastern Taiwan. Quartz, rutile/brookite and zircon are also found as associated submicron inclusions in garnet. Employing the reaction ilmenite+kyanite+quartz=almandine+rutile, and the breakdown of staurolite and quartz as thermobarometers, these submicron‐scale minerals formed at >8.3–8.8 kbar and < 660–690 °C. This P–T estimate is different from that (i.e. 5–7 kbar and 530–550 °C) derived from matrix minerals, which include almandine‐rich garnet, muscovite, chlorite, chloritoid, plagioclase, quartz and ilmenite. These results suggest that submicron inclusions in garnet‐like materials may record portions of the otherwise undocumented prograde path or provide information about previous metamorphic events and thus yield new insights into orogenic belts.  相似文献   

SOME ANALYSES OF RECENT CHINESE PROVINCIAL DATA     

David K. Y. Chu 《The Professional geographer》1982,34(4):431-437

A complete set of Chinese provincial data has recently been published and may be employed to study the regional variations in China. Great regional inequalities are found in industrial outputs, provisions of university places and distribution of qualified doctors.  相似文献   

地理学的逻辑方法和基本法则   总被引：5，自引：0，他引：5  

楚义芳 《地理学报》1988,(3)

从科学哲学和科学学的角度考察地理学思想史,可以发现:地理学之所以徘徊于科学性不强的“经验科学”的水平,关键在于其科学的理论化和系统化不够。本文对地理学的逻辑方法及其公理系统作了初步探讨,并尝试就此推演地理定理,估计地理学的未来发展趋势。  相似文献   

Ab initio prediction of 29Si-NMR chemical shifts     

Chu Shidong  Li Yingxia  Song Ni  Guan Huashi 《中国海洋大学学报(英文版)》2002,1(1):63-65

The ability of several ab initio models to predict experimental ²⁹Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B) and allytrimethylsilane (C) are calculated by GIAO, CSGT and IGAIM methods, using HF/6–31G^*, B3LYP/6-31G^*, HF/6–311+G^**, B3LYP/6–311+G^** and MPW1PW91/6–311+G^** models respectively. The ²⁹Si chemical shifts calculated by GIAO method using HF/6–311+G^** model are highly in agreement with those obtained experimentally. All of the models above reproduce the trends of chemical shifts in all cases studied, suggesting that the models are of practical value.  相似文献   

Radio emission characteristics of Pulsars and their magnetic dipole angle     

Wang Zhen-ru  Chu Yi 《Chinese Astronomy and Astrophysics》1981,5(4):438-440

We have made a statistical analysis on the subpulse width, the mean pulse width and the rate of change of polarization angle in pulsars. We obtained a number of empirical relations showing how these radio emission characteristics are related to the magnetic inclination and discussed the physical implications of the relations.  相似文献   

An Instability Theory of Ice-Air Interaction For the Migration of the Marginal Ice Zone     

P. C. Chu 《Geophysical Journal International》1986,86(3):863-883

  相似文献   

U-Pb zircon ages for the Luzhenguan Complex in northern part of the eastern Dabie orogen   总被引：4，自引：0，他引：4  

Wolfgang Siebe 《中国科学D辑(英文版)》2005,48(9):1357-1367

The Dabie Mountain is the collisional orogenic belt between the North China Block and the Yangtze Block. As the eastern segment of the central-China orogenic belt, its tectonic framework is corresponding to the Qinling orogenic belt as a whole[1]. The NHB in northern part of Dabie Orogen is regarded as the joint belt between the Yangtze Block and the North China Block, and roughly corresponds to the north Qinling belt of the Qinling orogenic belt, which separated the Tongbai-Dabie hig…  相似文献   

On the problem of land melioration on the Chinese Loess Plateau     

Xian-mo Zhu  S. M. Chu 《GeoJournal》1995,36(2-3):289-294

The Loess Plateau in Northwestern China, with 60 million inhabitants, is strongly endangered by heavy erosion quickly decreasing soil fertility and yield of crops, causing also severe problems in the main river of the area, uplifting its bed by strong sedimentation. This situation is mainly due to improper land use, cutting woods, ploughing up grasslands which are the consequence of the decreasing yield of former plough lands. This vicious cycle may only be disrupted by a proper land management based on the newest results of scientific research, on up to date data bases as well as on traditional methods. The land melioration methods must primarily aim at a prevention of further erosion and at an increase of infiltration by different methods, but all means of a proper country planning and development should be harmonised in order of halting of further deterioration of the area.  相似文献