钻孔应变差应变耦合系数反演与有关机理的探讨

研究反演分量式钻孔应变差应变耦合系数的方法,采用考虑方位角校正和相位滞后影响两种计算模型,计算结果显示大多数测站采用两种方法反演的耦合系数均比较相近,相位滞后、方位角校正以及拟合残差的结果相对稳定;但是有部分测站的差应变相位滞后偏离较大,从而导致采用两种方法反演的耦合系数差异较大。结合测站周边的构造分布,对可能导致该现象的物理机制进行了探讨。     

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潮汐应力与大震关系研究

选用1976—2009年全球震源深度小于70 km, M_W≥7.0的地震为研究对象, 利用震源机制解资料, 对每个地震的发震断层面进行了判断, 得到233个地震的发震断层面解。 据此, 本文讨论了发震时断层面上的地球固体潮汐剪应力方向与滑动方向的关系以及潮汐正应力在发震时所处的相位, 发震时断层面的库仑应力值。 结果表明, 当潮汐剪应力方向与滑动方向一致时触发作用最为明显, 逆断层地震与潮汐的关系最为密切; 而当潮汐剪应力方向与滑动方向相反时, 地震较少发生。     

X波段双极化雷达在北京夏季降水估测中的应用

利用X波段双极化雷达和地面自动雨量站数据对北京地区2009年夏季降水进行分析,先采用低通滤波、衰减订正等方法对数据质量进行控制,提取了单位差分传播相移Kdp之后,分别拟合出X波段双极化雷达参数与降水之间的两个关系式:Zh=159R1.37及R=13.9Kdp0.81,最后再分别利用这些拟合公式对北京地区进行降雨估测。结果表明:雷达用这两个公式估测的降雨量与地面实测降雨量有较好的一致性;且当每小时降雨量大于10mm时,Kdp-R的估测比Zh-R估测更稳定、准确;通过平均标准差统计可知,Kdp-R估测精度明显高于Zh-R估测精度。     

Interdecadal Variations of Phase Delays Between Two Ni(n)o Indices at Different Time Scales

Phase delays between two Nino indices-sea surface temperatures in Nino regions 1+2 and 3.4(1950-2001)-at different time scales are detected by wavelet analysis. Analysis results show that thereare two types of period bifurcations in the Nino indices and that period bifurcation points exist only in the region where the wavelet power is small. Interdecadal variation features of phase delays between the two indices vary with different time scales. In the periods of 40-72 months, the phase delay changes its sign in 1977: Nino 1+2 indices are 2-4 months earlier than Nino 3.4 indices before 1977, but 3-6 months later afterwards. In the periods of 20-40 months, however, the phase delay changes its sign in another way:Nino 1+2 indices are 1-4 months earlier before 1980 and during 1986-90, but 1-4 months later during 1980-83 and 1993-2001.     

铯原子喷泉钟低噪声频率综合器的研制

铯原子喷泉钟是现今的时间频率的基准,其中的频率综合器性能直接影响喷泉钟的稳定度性能.介绍了铯原子喷泉钟的低噪声频率综合器的设计和实现.对该频率综合器的测试表明,输出的9.2 GHz频率信号的相位噪声为-82 dB[Rad2/Hz]@offset1 Hz,满足设计要求.     

Installation of ocean bottom bases for observation of seafloor crustal movement

Abstract

Ocean bottom bases (OBBs) have been installed on both sides of the axis of the Sagami Trough east of the Izu Peninsula, central Japan, as the first step toward long‐term geodetic and geophysical observations at the plate boundary (subduction zone). The OBB is a platform for seafloor measurements; otherwise it is difficult to find an appropriate place for precise seafloor measurements in the subduction zones. It is made of a nonmagnetic concrete block of size 1100 × 1100 × 500 mm. It was lowered from a ship using a winch wire and installed on a predetermined place with its position being monitored by an acoustic transponder system and a 30‐kHz bottom pinger with an accuracy of about 2 m.

It was confirmed later during the divings on board the submersible Shinkai 2000 that the OBB was installed on a flat mud bottom in normal condition. No change has been recognized in the installation condition in 3 years; the OBB is stable enough to be used for acoustic range measurements on the seafloor as well as for several geophysical measurements.

The resolution of seafloor range measurement can be improved by two orders by using phase measurement techniques with the aid of pulse compression. Precise acoustic range measurement of the order of 10^?5 is feasible under the following conditions: two‐way measurements between the two OBBs installed on the slope facing each other with angles larger than 1.5°. Correction is necessary for the effect of long‐term temperature variation.     

双频载波相位求差法在周跳探测与修复中的应用

载波相位测量中小周跳的探测与修复一直是高精度GPS定位研究中的热点领域。分析了L1和L2载波相位观测值的关系,通过相邻历元的相位观测值求差来探测周跳,并结合伪距差分约束条件来确定及修复周跳。结合实例分析,证明该方法可以有效地探测并修复周跳,并通过Matlab编程实现了算法的程序化。     

塔里木盆地年平均气温的分形特征研究

根据分形理论、相空间嵌入定理、Grassberger和Procaccia提出的计算分维数的方法,对塔里木盆地22个气象台站50年(1956-2005)的年平均气温时间序列数据进行分析,计算其分维数,进一步应用普通克立格法、采用变异函数的指数模型对分维数进行了空间插值.研究结果表明.(1)该区域年平均气温的分维数为2.22～2.64,它提供了该区域气候吸引子的自相似结构的基本信息,表明模拟该区域气候系统至少需要3个独立变量,(2)分形维数的空间分布与地形地理位置密切相关,在地形地势复杂的地方及有地表径流的地方分维数的值较高,譬如在盆地边缘砾石带、盆地边缘绿洲带、盆地东部的罗布泊湖盆区分形维数均较高,约为2.55～2.57,表明这些地方气候变化较为复杂,沙漠腹地分形维数较低,约为2.51～2.55,气候系统的复杂性相对较低.     

用Sp震相测定北京地震台附近的地壳厚度

根据CDSN北京地震台宽频带数字地震仪记录到的20个远震记录中的S震相与Sp震相的到时差测定了北京地震台附近地壳厚度值H。得出了以北京地震台为圆心20～45km环形区域内地壳厚度平均值为40．2km左右的结果。并简要的讨论了Sp震相在北京地震台的记录特征。初步得出了Sp震相在北京地震台的可观测范围为11°～40°,S波震相高效率转换为Sp震相的距离约在30°的结果。