The magmatic activity mechanism of the fossil spreading center in the Southwest sub-basin,South China Sea

Petrogeochemical data indicate that after the end of seafloor spreading,residual magmatic activity still exists in the deep basin of the South China Sea.By using different viscous structure models beneath the fossil spreading center of the Southwest sub-basin we simulated the amount of melt produced,the length of the melting period,and the thermal evolution process in terms of geothermics and the buoyant decompression melting mechanism.We compared the results of our model with observed heat flow,seismic,and petrogeochemistry data.The results show that depletion buoyancy induced by buoyant decompression melting plays an important role in the melting process,while retention buoyancy,thermal buoyancy,and viscous shear force have only a weak influence on the melting process.From the length of the melting period,we determined that for the three viscous structures models the magmatic activity lasted about 5,12,and 15 Ma.Under the effect of buoyant depression melting,local high-temperature areas will develop under the basin,which can explain the low-velocity layer detected by seismic exploration in the middle and upper lithosphere of the Southwest sub-basin.We also simulated the possible lithology distribution beneath the fossil spreading center with the physical conditions of different viscous structure,different temperature structure,and different melting fraction,which provided a greater understanding of the rock petrogeochemical data of the deep sea basin in the South China Sea.     

基于全天空极光图像方向能量表征方法的极光事件分类

针对基于全天空极光图像的极光事件自动分类问题,提出一种基于方向能量二元编码重组表征的自动分类方法。首先,通过对多个方向上能量分解来描述极光事件中的局部纹理和各个方向上的运动信息,并且结合分块策略获得极光事件的全局形态信息;然后,借鉴一种二元编码重组的方式对多个方向能量进行融合,从而使得极光事件的表征具有同时表征局部纹理、全局形态和运动信息的能力。该表征方法完全不依赖于极光事件的长度,可用于表征不同持续时间的极光事件,并且不需要复杂的训练过程。利用最近邻和支撑向量机分类器分别对从中国北极黄河站拍摄到的极光图像中挑选的特定极光事件进行自动分类,结果表明,与其他两种典型的动态纹理描述方法相比,本文所提出的表征方法结合最近邻分类器,得到了最好的分类效果,能有效用于极光事件的分析,为海量数据中的极光事件自动分类提供了一种新方法。     

关于辽宁地区b值方法定量预测的研究

本文利用地震学分析预报方法程式指南和“八五”攻关成果中提出的地震b值定量预测方法,对辽宁及邻区1969年以来发生的8次地震震例作了回顾性检验研究。在此基础上,根据震前b值的变化特征,总结出了可能适用于辽宁地区半年左右尺度的b值预测方法的异常羊别指标及预报规则。     

川藏公路“102”滑坡群的基本特征

“102”滑坡群位于川藏公路西藏波密县境内的通麦“102”地段.该地段滑坡成群分布,在约3km长的范围内,共有大小滑坡22处,其中直接危害川藏公路且规模较大的滑坡有6处.     

美国板块边界观测(PBO)中的钻孔应变观测设备

介绍美国的板块边界观测(PBO)项目中的钻孔应变观测和钻孔应变观测设备,如钻孔应变仪、钻孔应变仪的辅助观测设备、数据采集、数据传输、电源系统、仪器的防护装置等,并介绍其技术要求.     

Computing the Light Periods of Blazars with the Periodogram Spectral Analysis Method

The periodogram spectral analysis method applicable to equallyspaced time series is discussed, and the method is tested first with a simulated data series. It is confirmed that this method is effective for noisy series. Then, applying this method to the analysis of the light periods of the quasars 3C 279 and 3C 345 as well as the BL Lac objects OJ 287 and ON 231, we obtain their light periods to be 7.14 yr, 10.00 yr, 11.76 yr and 6.80 yr, respectively. These results obtained by periodogram spectral analysis are consistent with those obtained by the Jurkevich method in the literature. We have analyzed the effects of different window functions, and commented on their correct selection in practical applications.     

南极乔治王岛长城湾沿岸固定冰中有色层生态观察

自1988年11月至1989年3月,对南极乔治王岛的长城湾沿岸水域中的海洋生物和环境因子进行了调查,1988年11月20日在2号站采得的冰芯中部有一层约5cm的棕色层,而1988年11月17日、20日和26日在5号站采得的冰芯样中有二层棕色层。固定冰中叶绿素a浓度范围在2.55～56.8mg/m~3之间,而且大部分含量集中在海冰的中间层中,而不象其它海区如昭和、戴维斯、凯西和麦克默多等站,大部分叶绿素a集中在海冰的底部,造成这种差别的原因、可能是由于海冰的结构和形成过程不同所致。     

Discovery of 13 New Variable Stars in the Field of the Open Cluster NGC 2168 （M35）

A wide-field time-series CCD photometric survey of variable stars in the field of the open cluster NGC 2168 was carried out using the BATC Schmidt telescope. In total 13 new variable stars are discovered with three W UMa systems, one EA type and two EB type eclipsing binaries (one of them could be a W UMa system), and seven pulsating stars including three candidates of δScuti stars.     

A New Solar Radio Spectrometer at 1.10-2.06 GHz and First Observational Results

An improved Solar Radio Spectrometer working at 1.10-2.06 GHz with much improved spectral and temporal resolution, has been accomplished by the National Astronomical Observatories and Hebei Semiconductor Research Institute, based on an old spectrometer at 1-2 GHz. The new spectrometer has a spectral resolution of 4 MHz and a temporal resolution of 5ms, with an instantaneous detectable range from 0.02 to 10 times of the quiet Sun flux. It can measure both left and right circular polarization with an accuracy of 10% in degree of polarization. Some results of preliminary observations that could not be recorded by the old spectrometer at 1-2 GHz are presented.