Time–frequency representation of earthquake accelerograms and inelastic structural response records using the adaptive chirplet decomposition and empirical mode decomposition

In this paper, the adaptive chirplet decomposition combined with the Wigner-Ville transform and the empirical mode decomposition combined with the Hilbert transform are employed to process various non-stationary signals (strong ground motions and structural responses). The efficacy of these two adaptive techniques for capturing the temporal evolution of the frequency content of specific seismic signals is assessed. In this respect, two near-field and two far-field seismic accelerograms are analyzed. Further, a similar analysis is performed for records pertaining to the response of a 20-story steel frame benchmark building excited by one of the four accelerograms scaled by appropriate factors to simulate undamaged and severely damaged conditions for the structure. It is shown that the derived joint time–frequency representations of the response time histories capture quite effectively the influence of non-linearity on the variation of the effective natural frequencies of a structural system during the evolution of a seismic event; in this context, tracing the mean instantaneous frequency of records of critical structural responses is adopted.The study suggests, overall, that the aforementioned techniques are quite viable tools for detecting and monitoring damage to constructed facilities exposed to seismic excitations.     

Gauss-Markov模型参数的岭型广义逆估计及其优良性

本文继续文献 [10 ]的工作 ,进一步讨论了测量平差 Gauss- Markov模型参数岭型广义逆估计的若干性质 ,如允许性、优效性、相对效率、抗干扰性等等 ,得到了许多重要结论。计算结果表明 ,在设计阵呈病态时 ,岭型广义逆估计确能明显改善 L S估计     

岩石矿物及粉尘中游离二氧化硅的测定

改进了游离二氧化硅（fSiO2)测定中试样的分解方法，采用硫－磷混酸替代单独使用磷酸分解试样，防止了焦磷酸盐的形成，同时，氟硼酸对fSiO2的溶解率符合测定要求。改进的方法用于标准物质中fSiO2的测定，结果与标准值或磷酸溶矿重量法相符。对于ω(fSiO2)=3.26%的标样10次测定的RSD为2．4％。     

基于小波多分辨率分析方法的海冰遥感影像数据融合

采用小波多分辨率分析方法，对辽东湾2000－01－18的海冰遥感数据（NOAA／ARHRR和Radarsat/ScanSAR)进行了融合分析，并从几方面对结果作了深入的分析和对比。文中首次采用了小波分析中的多层次分解和重构技术用于数据融合分析。     

一个有限差分大气环流模式的并行效率

适合于大规模并行处理机（ＭＰＰ）的中国科学院大气物理研究所新一代九层大气环流模式（ＩＡＰ ９Ｌ ＡＧＣＭ）被发展成功。本文描述了并行模式的设计原则，给出了该模式的并行版本在我国几种主要的并行机上的并行执行效率数据。采用消息传递方式（ＭＰＩ）的区域分解方法用于实现程序的并行，结果表明，对于该模式，只有一维区域分解方法才能取得较好的并行可扩展性，即随着处理器的增加而能得到相应较好的并行加速比和并行效率。     

SYNERGISTIC EFFECTS ON ATMOSPHERIC ANOMALY OF THE TROPICAL INDIAN AND PACIFIC OCEANS IN NORTHERN WINTER

In terms of observational analysis and numerical simulations,study is performed of thesynergistic effects of the tropical Indian Ocean and Pacific SSTA on the atmosphere in northern win-ter.It turns out that the SSTA features show in-phase variation for the Indian Ocean and the central/eastern Pacific at low latitudes and anti-phase change compared with that in the neighborhood of thewestern Pacific“warming pool”.When negative SSTA in the western Pacific and positive SSTA inthe central/eastern Pacific and the Indian Ocean are available,the 500 hPa height anomaly exhibits awave train of a positive-negative-positive anomaly following a great-circle path emanating from thesubtropical western Pacific via the NW portion to North America,with enhanced westerly jet overmidlatitude East Asia and the NW Pacific,and v.v.The comparison to the results from the numeri-cal modeling of the tropical western Pacific SSTA reveals the importance of the synergistic effects ofthe oceans on atmospheric circulations.     

非单一电离层扰动场的台阵探测分析

真实的ＴＩＤ一类大尺度电离层扰动是非平稳和色散的，而且是统计非单一的．本文首先给出了描述这种真实扰动场的数学模型，进而导出了联系台阵探测可测量与扰动场传播参量的观测方程，在此基础上提出了求解观测方程的时频分析方法．这一台阵探测数据分析的新方法，既能分离出非单一电离层扰动场中各种准单一扰动成分，又能获得准单一扰动成分传播参量随时间的演变和随频率的色散．分析实例表明，本文方法分辨率好，精度高，结果可靠，是适用于ＴＩＤ一类大尺度电离层扰动台阵探测数据分析的有效方法．     

重力学反问题中零外部位密度的研究

对重力学反问题研究中零外部位密度的数学性质及物理意义进行了系统研究和分析．首先从基本定义及条件的描述入手，推演出其数学表示和限制，由此揭示重力学反问题的非适定性形态，进而论及其与非零外部位密度之间的数学关系．由此证明对应于给定外部位的场源函数可以分解成零外部位密度与调和密度的直和．通过对其物理意义的讨论，为地球物理反演非零外部位场源及物理大地测量学构制等效场源提供理论依据．     

Modeling,ray tracing,and block nonlinear travel-time inversion in 3D

We describe an integrated forward and inverse three-dimensional modeling system that can deal with complex geological structures. The system has been designed to handle large-scale problems by using a distributed approach. It uses seismic ray tracing for forward simulation, time-to-depth mapping, and nonlinear travel-time inversion.A novel decomposition method is our tool to attack large-scale problems in a parallel approach. The system is fully implemented and we demonstrate its performance with synthetic examples.This research was partially supported by the National Science Foundation under SBIR Grant III-9300992.     

A NEW RECEPTOR MODEL:A DIRECT TRILINEAR DECOMPOSITION FOLLOWED BY A MATRIX RECONSTRUCTION

In many cases,monitoring data for ambient airborne particles can be organized in the form of a three-way data table with one way for chemical species,one for sampling periods and one for sites.A directtrilinear decomposition followed by a matrix reconstruction(DTDMR)is developed to analyze such adata table as a whole.The three-way data set is composed into three two-way matrices by a direct trilineardecomposition(DTD).The column vectors of each of the matrices are called‘source profiles’,‘emissionpatterns’and‘site coefficients’respectively.Particulate sources are identified by examining both theirsource profiles and emission patterns.After the sources have been identified,emission patterns and sitecoefficients are used to produce a three-way matrix that gives estimates of mass contributions of sourcesto the samples collected at every site in every period.By simulation study,not only has the method beenverified,but a good indicator has been found that shows the number of factors(i.e.sources)in thesystem.Unlike other receptor models,DTDMR does not require source profile data and does not involvetrial-and-error procedures.Since DTDMR identifies sources based on variations in two dimensions,it hasa higher potential to distinguish two sources that have similar chemical compositions.The DTDMRmodel has provided excellent results with simulated data and has been applied in a real world three-waydata set.