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951.
Reciprocity theorem to compute the static deformation due to a point dislocation buried in a spherically symmetric earth 总被引:4,自引:0,他引:4
Shuhei Okubo 《Geophysical Journal International》1993,115(3):921-928
Intriguing reciprocity relations exist between the static deformation excited by a point dislocation in a SNREI earth and those generated by external forces, such as tidal force, surface loading and surface shear forces. Coseismic deformations can be rewritten as follows: (1) potential change in terms of the tide deformation field, (2) radial displacement in terms of the load and tidal deformation fields, and (3) tangential displacement in terms of shear and torsional deformation fields. The relations greatly reduce the effort to compute the coseismic crustal deformation in a spherically symmetric earth. 相似文献
952.
We invert ISC PcP and PKP absolute and differential traveltimes in an attempt to infer the long-wavelength topography of the core-mantle boundary (CMB). The data selection and processing methods are described and evaluated. These travel-time data are very noisy and the geographic distribution of the data is highly non-uniform, inhibiting reliable inference of CMB topography. Spatial averaging enhances the coherent component of the residual variance (related to heterogeneity), however, the random component of the variance is much larger than the coherent component. We show that for PcP data the coherent signal due to mantle heterogeneity overshadows that arising from the CMB, and that the effects of mantle heterogeneity are mapped into our inferred CMB solutions. The PcP data are not correlated across the spatial averaging bins and seem to have a strong bias due to small-scale structure and/or noise. The non-uniform geographic sampling of the data plays a role in the mapping of mantle heterogeneity onto the CMB. Spatial patterns of CMB models inferred from different phases do not agree. Amplitudes of seismically inferred CMB undulations vary greatly. The sensitivity of inferred CMB models to the processing, spatial averaging procedure, and inversion techniques are investigated. Topographic amplitudes increase strongly with increasing input residual variance. The power spectrum of inferred topography indicates that there are unmodelled heterogeneities that must be described with spherical harmonics of degree 6 and higher. Based on this work, we conclude that reliable inference of long-wavelength CMB topography is not likely with the current ISC data set or with a spherical harmonic expansion truncated to degree and order 6. 相似文献
953.
954.
A STUDY ON THE RELATIONSHIPS OF THE NUTRIENTS NEAR THE CHANGJIANG RIVER ESTUARY WITH THE FLOW OF THE CHANGJIANG RIVER WATER 总被引:5,自引:1,他引:5
沈志良 《中国海洋湖沼学报》1993,11(3):260-267
Investigations from August, 1985 to July , 1986 showed that the high concentration area of PO4-P , SiO3-Si and NO3-N gradually reduced with the reduction of the area of the Changjiang River diluted water from summer, autumn to winter , and that the seasonal distributions and variations of the nutrients concentrations were mainly controlled by the river flow and were also related to the growth and decline of phytoplankton . The conservation of SiO3-Si and NO3-N in the estuary in the flood season was poorer than that in the dry season .. The behaviour of PO4-P in the estuary shows that aside from -biological removal, buffering of PCU-P is possible in the estuary . The highest monthly average concentrations and annual average concentrations in the river mouth were respectively 0.88 and 0.57 umol/L for PO4-P,191.5 and 96.2 umol/L for SiO3-Si, and 81.6 and 58.6 umol/L for NOs-N . The Changjiang's annual transports of PO4-P , SiO3-Si and NO3-N to the sea were about 1.4×104tons , 204.4×104 tons and 63.6×104 相似文献
955.
A PRELIMINARY ANALYSIS ON THE CHARACTERISTICS OF THE KUROSHIO FRONTAL EDDY IN THE EAST CHINA SEA IN SPRING 总被引:3,自引:0,他引:3
The Kuroshi'o front eddy's surface and sectional isothermal distribution characteristics were analyzed on the basis of observation data obtained in April 13-16 of 1989 in the East China Sea. It was found from the similarity between these isothermal distributions with those in January and beginning of June for the years 1986-1990 that the Kuroshio front eddy often occurred from March to the beginning of June. The Kuroshio front eddy movement in the East China Sea in spring was along two routes: the Okinawa Trough route, and the continental shelf slope route. The two moving routes both in the surface layer and in the section are described, their causes are discussed, and differences are compared. 相似文献
956.
957.
958.
Xia Zhenhuan. Professor Dept. Hydraulic Engineering. Tsinshua University. Song Genpei. Lecturer. kept. Hydraulic Engineering. Tsinghua University. Chen Yiping. Assistant. Dept. Hydraulic Engineerins Tsomghua University Wang Gang. Engineer. Research institute of Naval Engineering. PLA 《国际泥沙研究》1990,(1)
1. INTRODUCTIONAs a wide range of size distirbution including usually a certain POrtion of cohesive material is thecommon feature of the sediment constituting hyperconcentrated flows. it is desirable to study the settling properties of mixtures of cohesive and non--cohesjve sediment particles at high concentrations.Past studies on the settling of discrete particles in a suspension of fine cohesjve sediment is scarcein the literature. The Sediment Research Laboratory of Tsinghua Universi… 相似文献
959.
电离层赤道异常两日振荡的数值模拟 总被引:1,自引:0,他引:1
近20年来,国外学者对电离层赤道异常问题的数值模拟研究未考虑到大气行星波对潮汐发电机电场的调制效应,因而不能解释赤道异常峰值的逐日变化.本文结果表明二日波对F_2区电子浓度的输运有很大影响.这一方法可以推广到赤道异常各种长周期行星波振荡的数值研究. 本文从非定常等离子体连续方程出发,建立包含行星波振荡对E×B漂移的调制效应的方程,并给出数值模拟的方法以及可与实际观测进行比较的结果.文中取二日波漂移振幅为U_p=0 m/s、5m/s、10m/s,而初位相分别为φ=0°、90°共四种情形进行了模拟,结果表明,二日波的调制可使赤道异常的时空分布以及异常峰值产生明显的逐日变化.在所选取的模型中,取U_p=5m/s,φ=0°所得到的f_0F_2t的二日分布特征与观测较吻合.而u_p约5m/s的变化能引起异常峰值f_0F_2约1-2MHz的起伏,而二天之内f_0F_2的二个峰值表现出约2-4MHz的起伏. 相似文献