Organic/ Inorganic Occurrence of Metallic Elements of the Black Shale-Hosted Baiguoyuan Silver-Vanadium Deposit in Xingshan, Hubei

By means of kerogen purification, the proton induced X-ray emission (PIXE) and instrumental neutron activation analysis (INAA), the authors have studied the organic/inorganic occurrence modes of the metallic elements of the Baiguoyuan silver-vanadium deposit hosted in black shale in Hubei Province, China. The result shows that Au, Hg and Ta have a strong tendency to occur organically, with more than 70% of these elements being associated organically. Se, Ga, Ag and Hf are partly associated with organic matter, with more than 20% of them occurring organically. Compared with the above elements, Zn, Cu, As and Sb are weakly associated organically, and tend to be enriched in kerogen. However, Mn, Th, U, V, Co, Cr, Al, Fe and Sc usually occur inorganically. Of the rare earth elements (REE), La, Ce, Tb, Dy, Yb and Lu have stronger ability to be associated with organic matter than Sm and Eu.     

The focal mechanism solution of the M s 6.5 Wuding earthquake in Yunnan Province of October 24, 1995

The focal mechanism of Wuding earthquake with magnitude M=6.5 on October 24, 1995 is estimated by the method of inversion of seismic tensor in this paper. The two principal axes are nearly horizontal, the principal compressive axis is about N30°E, the nodal plane which strikes about N105°E (N75°W) is probably consistent with the actual rupture plane.     

The form of Newtonian cooling in atmospheric tidal theory

The different forms of the classical atmospheric tidal vertical structure equation derived by Lindzen and McKenzie (1967) and by Dickinson and Geller (1968) are shown to be due solely to their different treatment of the infrared radiative damping of tidal temperature perturbations. While both parameterize the infrared cooling as a Newtonian cooling, the former use the tidal temperature perturbation along a constant geometric height surface while the latter use the perturbation along a constant pressure surface. These two tidal temperature perturbations differ when the background atmospheric temperature varies with height. Scaling arguments show that for most applications the differences between the use of these two forms of Newtonian cooling are negligible. However, relative differences of 30% in amplitude and 15° in phase can occur in the Martian atmosphere, with its relatively short radiative time constants, for a possibly resonant planetary-scale Rossby tidal mode.     

Revisiting the Phasor-Walkout method for detailed investigation of harmonic signals in time series

A well-known but rarely used powerful method to investigate the presence of harmonic signals in time series is the Phasor Walkout method (other names are: Graphical Fourier Transform, Summation Dial, Complex Demodulation). At a given test frequency the complex contributions (phasors) to the Fourier Transform of each sample in an equidistantly sampled series are added vectorially in the complex plane. The resulting pattern, the walkout, reveals information about the properties of the signal which is not easy to obtain by other methods. Synthetic examples are used to demonstrate the resolving power of the method. The following geophysical examples for the application of this method are shown: determination of the frequency of the breathing mode₀ S ₀ of the earth after a large earthquake; the study of superconducting gravimeter records after a large deep earthquake used in the core mode interpretation of a spectral peak, the study of the residualS ₃ (8 h period) signal in a tidal record and the bichromatic Rayleigh-waves from Mount Pinatubo on June 15, 1991.     

System identification of linear structures based on Hilbert–Huang spectral analysis. Part 1: normal modes

Based on the Hilbert–Huang spectral analysis, a method is proposed to identify multi‐degree‐of‐freedom (MDOF) linear systems using measured free vibration time histories. For MDOF systems, the normal modes have been assumed to exist. In this method, the measured response data, which are polluted by noises, are first decomposed into modal responses using the empirical mode decomposition (EMD) approach with intermittency criteria. Then, the Hilbert transform is applied to each modal response to obtain the instantaneous amplitude and phase angle time histories. A linear least‐square fit procedure is proposed to identify the natural frequency and damping ratio from the instantaneous amplitude and phase angle for each modal response. Based on a single measurement of the free vibration time history at one appropriate location, natural frequencies and damping ratios can be identified. When the responses at all degrees of freedom are measured, the mode shapes and the physical mass, damping and stiffness matrices of the structure can be determined. The applications of the proposed method are illustrated using three linear systems with different dynamic characteristics. Numerical simulation results demonstrate that the proposed system identification method yields quite accurate results, and it offers a new and effective tool for the system identification of linear structures in which normal modes exist. Copyright © 2003 John Wiley & Sons, Ltd.     

皖南山区生态经济发展模式与对策

文章在分析皖南山区存在的主要生态经济问题基础上。提出了适合皖南山区的5种生态经济发展模式；（1）生态农业发展模式；（2）旅－农－工－贸联动发展模式；（3）生态恢复与重建模式；（4）山区综合开发模式；（5）庭院生态经济模式。文章最后对皖南山区发展生态经济，实现生态系统与经济系统的良性循环提出了具体建议。