A new inverse method and application to ocean data

A new method is proposed to inverse normalization data of hidden variables in a dynamical system by embedding a time series in multidimensional spaces and applying a normalization analysis to the conditional probability density of points in the reconstructed phase spaces. The method is robust in the application to Lorenz system and 4-dimensional R?ssler system by testing quantitatively and qualitatively the correlation coefficient between inverse data and original data in time domain and in frequency domain, respectively. By applying the method to analyzing the South China Sea data, the normalization data of wind speed is extracted from the sea surface temperature time series.     

泉州台763长周期地震仪的震相记录特征

76 3长周期地震仪 1 997年起取代基式仪 ,承担我国一类合网对国内外地震的监测和对外观测资料交换任务。本文介绍了我台 76 3长周期地震仪的震相记录特征 ,有利于台站对震相的分析 ,提高对外资料交换和大震速报水平。     

反相流动注射催化光度法测定废水中的亚硝酸根

采用反相流动注射技术与催化光度法相结合，用微机化流动注射分析仪准确控制反应时间，优化了实验条件，克服了催化光度法反应时间难以控制引起的方法精密度、准确度不高的弱点，拟定了测定痕量亚硝酸根的流动注射催化光度方法。分析速度第小时20次，NO2^- 质量浓度在0．00－2．00mg/L，回归方程斜率为0．155。方法直接测定电厂测水中NO2^-的结果与Griess法相符合，RSD＜5．0％（n=5）。     

Evaluation of response and energy in actively controlled structures

A computational method of energy evaluation is derived to study the elastic responses and energy distribution of actively controlled single‐degree‐of‐freedom (SDOF) structures during earthquakes. Contrary to the common perception that applying active control force pumps energy into the structure, the applied control force can actually reduce the energy in the structure by reducing the input energy from earthquakes to the structure. In addition, applying control force can dissipate a large amount of energy in the structure when this control force is applied in the direction opposite to the displacement and velocity responses. To demonstrate this energy mechanism in active controlled structures, the two most popular control algorithms, optimal linear control (OLC) and instantaneous optimal control (IOC) algorithms, are used to calculate the control response and energy spectra. One‐step time delay is incorporated into the algorithms to take into consideration the practical aspect of active control. The effects of different earthquakes and damping ratios on control energy and response spectra are studied. These studies show that both OLC and IOC are very effective in reducing the structural displacement and velocity responses by reducing the input earthquake energy as well as dissipating a large amount of energy in the structure. Copyright © 2001 John Wiley & Sons, Ltd.     

Determination of structures of Ca2CoSi2O7, Ca2MgSi2O7, and Ca2(Mg0.55Fe0.45)Si2O7 in incommensurate and normal phases and observation of diffuse streaks at high temperature

 The structures of Ca₂CoSi₂O₇, Ca₂MgSi₂O₇, and Ca₂(Mg_0.55Fe_0.45)Si₂O₇ have been determined in the temperature range between 297 and 773 K with arbitrary intervals. The structures of the incommensurate phase of the three compounds are characterized by the presence of the six-, seven-, and eight-coordinated Ca–O polyhedra and of the bundles along the c-axes consisting of four arrays of the six-coordinated Ca–O polyhedra and an array of T¹O₄ (T¹: Co, Mg, or Mg–Fe) tetrahedra in the structures. The number of bundles in each material decreases at elevated temperatures. The incommensurate phase undergoes a phase transition into the normal phase at 493 K in Ca₂CoSi₂O₇, at 360 K in Ca₂MgSi₂O₇, and at 510 K in Ca₂(Mg_0.55Fe_0.45)Si₂O₇. The features of the structures of the normal phase are almost the same as those found in the basic structures (the averaged structures of the incommensurate structures), and this fact implies that the characteristics of the structures, such as the six-coordinated Ca–O polyhedra or fragments of the bundles, should be partially preserved at higher temperatures both in the incommensurate structures and also in the structures of the normal phase. Analyses of anisotropic displacement parameters clarified that disorder of the modulation waves is developed in the structures at higher temperatures. The evolution of a disorder in the structures was ascertained by observation of the circular diffuse streaks in the vicinity of the transition temperature between the incommensurate and normal phases. Received: 3 July 2000 / Accepted: 26 October 2000     

山东省干旱演变规律及其影响

利用近５００年旱涝资料分析了干旱对山东省农业，工业及环境的危害。利用功率谱和模糊判别函数研究了旱涝的周期性和阶段性，指出旱涝的演变规律可为气候预测提供依据。     

ALow-order Model of Two-dimensional Fluid Dynamics on the Surface of a Sphere

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Amplitude Ratio of Regional Seismic Phases: An Efficient Indicator of Thermal State of the Lithosphere

By analyzing seismograms of short period records at the Beijing SeismoJogicaJ Observatory, the present paper investigates the amplitude ratio of seismic phases. The results indicate that the amplitude ratio of Sn/Lg is correlated with the lithosphere structure, the thermal state, and strong earthquake occurrence in the region the seismic rays pass through. The significance of such a correlation in the study on the genesis and prediction of strong earthquakes is discussed.     

Inversion of Q value structure beneath the Tibet Plateau

A total of 11 earthquakes with 15 Rayleigh wave paths, recorded at 11 broadband digital PASSCAL seismometers installed in the Tibet Plateau by the Sino-U.S. joint research group, were used to determine the phase velocity and attenuation coefficient of surface waves in periods of 10–130 s. The average shear wave velocity and quality factor {ie271-1} structures in the crust and upper mantle were obtained in this region. The result shows the average {ie271-2} is low and there exists a high attenuation ({ie271-3}=93–141) layer in the crust. The depth range of the low {ie271-4} value layer (16–42 km) is consistent with the range of low velocity layer (21–51 km) in the crust. Below 63 km in the lower crust, {ie271-5} decreases with depth from 114 to 34 at depth of 180 km. The low shear wave velocity and low value of {ie271-6} at the same depth range in the crust indicate that the rocks in the range is probably melted or partially melted. According to the shear wave velocity structure, the average thickness of the crust is about 71 km and a clear velocity discontiniuty appears at the depth of 51 km. The low-velocity zone (4. 26 km/s) at depth of 96–180 km may be corresponding to the asthenosphere. Contribution No. 96A0047, Institute of Geophysics, SSB, China. This study was supported by the National Natural Science Foundation of China.     

Study on the characteristics of crust－mantle transition zone in Western Yunnan Province

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