De-A-steroids in immature marine shales

Three series of de-A-diasterenes have been observed in a variety of immature marine shales. Two of them have been identified by comparison with authentic standards and the structures of the third assigned by extrapolation. The greater complexity in the number of series compared with diasterenes indicates that the ring A degradation occurred to differing extents. The rate of C-20 diagenetic isomerisation in the de-A-diasterenes proceeds at a similar rate to that in diasterenes. Two series of B-ring monoaromatic de-A-steroid hydrocarbons have also been found. Comparison with the B-ring monoaromatic anthrasteroids indicates that the de-A-compounds are 14α(H) and 14β(H) isomers. Diagenetic isomerisation of the 14α(H) isomers to the more stable 14β(H) isomers occurs at a rate similar to that in the B-ring monoaromatic anthrasteroid series.     

迭部5.9级地震爆破地震波动力学特性的变化

本文利用遥测传输台网可见记录和磁带记录对厂坝炮爆破进行地震波动力学特性分析,发现各次爆破记录有一致性。对失真信号进行滤波处理,经凝聚函数分析证明了爆源的一致性。对1987年1月8日迭部Ms=5.9地震的分析,表明由于介质状态的改变,记录到的地震波优势频率向高频方向移动。在近震中有关台站上,地震波位移谱出现多峰与能量分散现象,拐角频率也向高频方向移动,振幅比呈现低—高—发震的形态。在地震前二十几天,主频处地震波衰减小,而震后明显变大。上述特征可能与该地震孕育过程中应力水平和介质状态变化有关。     

Empirically derived relationships between fractal dimension and power law form frequency spectra

Fractal analysis and Fourier analysis are independent techniques for quantitatively describing the variability of natural figures. Both methods have been applied to a variety of natural phenomena. Previous analytical work has formulated relationships between the fractal dimension and power law form frequency spectrum.Mandelbrot (1985) has shown that difficulties arise when the ruler method for measuring dimensionality is applied to other than self-similar figures. Since an investigator presumably does not know in advance the dimensionality of a natural profile, it is essential to quantify the nature of the discrepancy for self-affine cases. In this study, a series of experiments are conducted in which discrete random series of specified spectral forms are analyzed using the fractal ruler method. The various parameters of the fractal measurement are related to the parameters of the spectral model. In this way, empirical relationships between the techniques can be derived for discrete, finite series which simulate the results of applying the fractal method to observational data.The results of the study indicate that there are considerable discrepancies between the results predicted by theory and those derived empirically. The fundamental power law form of length versus resolution pairs does not hold over the entire region of analysis. The predicted linear relationship between fractal dimension and exponent of the frequency spectrum does not hold, and the spectral signals can be extended beyond the limits of dimension inferred by theory. Root-mean-square variability is also shown to be linearly related to the fractal intercept term. An investigation of the effect of nonstationary sampling is conducted by generating signals composed of segments of differing spectral characteristics. Fractal analyses of these signals appear identical to those conducted on stationary series.The discrepancies between theoretical prediction and empirical results described in this study reflect the difficulties of applying analytically derived techniques to measurement data. Both Fourier and fractal techniques are formulated through rigorous mathematics, assuming various conditions for the underlying signal. When these techniques are applied to discrete, finite length, nonstationary series, certain statistical transformations must be applied to the data. Methods such as windowing, prewhitening, and anti-aliasing filters have been developed over many years for use with Fourier analysis. At present, no such statistical theory exists for use with fractal analysis. It is apparent from the results of this study that such a statistical foundation is required before the fractal ruler method can be routinely applied to observational data.     

地球现代板块运动的天文和人卫多普勒测定

本文根据作者首次得到的全球113架光学天文仪器观测纲要的数千个星组未知数G,计算研究了1962-1982年间地球板块运动的某些方面.同时还根据1973-1983年间人卫多普勒的测量结果进行了相应的研究.这两种独立的技术其测量结果符合较好,且与地球物理和VLBI的测量结果相吻合.     

以单多普勒雷达观测资料反演冷锋流场的试验

通过对一次欧洲冷锋过程单多普勒雷达立体扫描资料的实例计算来考察用ＶＡＤ（ＶｅｌｏｃｉｔｙＡｚｉｍｕｔｈＤｉｓｐｌａｙ）方法反演锋面在垂直剖面图上的风场和用ＶＡＰ（ＶｅｌｏｃｉｔｙＡｚｉｍｕｔｈＰｒｏｃｅｓｓｉｎｇ）方法反演水平风场的可能性。反演结果不仅显著展示了锋面两侧的风向切变，而且也展示出气团内部风场中存在的中尺度结构。由于ＶＡＰ方法对距离圈上多普勒速度随方位的变化非常敏感（多普勒速度的脉动）     

用X射线光谱法测定锰的X射线发射谱的细结构及锰的价态分析

在普通的ＸＲＦ光谱仪上测定金属锰，氧化锰、锰的化合物中ＭｎＫβ发射谱带，经谱数据处理获得了谱线的轮廓线及谱峰参数（峰位，峰高，峰宽，峰宽，峰函数比例因子，不对称因子）；研究了谱参数与价态间的关系。结果表明ＭｎＫβ谱带结构与化合价，氧化数，化学键及配位状况有关，利用所得出的规律对太平洋锰结核的价态作了定性测定，并用谱峰分解法对Ｍｎ３Ｏ４试样进行化学价态定量分析的浓度量，得到满意的结果。     

贝叶斯网络支持的地表参数混合反演模式研究

基于贝叶斯网络理论，建立用于植被地表参数估计的混合反演模式，结合遥感物理模型实现了冬小麦叶片叶绿素含量（Cab）和冠层叶面积指数（LAI）的反演。用模型模拟数据以及2001年顺义遥感实验数据验证结果表明，LAI和Cab均有较好的反演精度。针对含噪声模拟数据反演结果中约有10％的噪声数据反演失败的情况，用不确定知识的处理方法有效地降低了失败点的比例。混合反演模式本质上是一个融合先验知识与观测数据的知识推理方案，本文实现了对反演过程中参数后验概率更新算法并引入热力学中的信息熵概念实现了参数后验信息动态定量计算，同时简单探讨了现阶段定量评价遥感反演过程中信息流控制存在的难点问题。     

利用夫琅和费暗线探测自然光条件下的植被光合作用荧光研究

自然光照条件下测定的植被反射的辐照度光谱既包括太阳光诱导荧光的发射光谱，又包括叶片对入射光的反射光谱，研究如何从冠层光谱中提取荧光光谱有十分重要的应用价值。首先，论文介绍了夫琅和费暗线探测自然光条件下的光合作用荧光的基本原理和方法。其次，将太阳大气的夫琅和费暗线拓展到地球大气，发现地物光谱仪测定的冠层辐照度光谱中688nm和760nm两个氧气吸收形成的夫琅和费暗线特征明显，且荧光较强，所以利用这两个波段的夫琅和费暗线可以探测自然光条件下的光合作用荧光。第三，研究并分析了夫琅和费暗线方法计算的688nm和760nm波段的荧光特性，结果表明该方法计算的荧光是可靠的，它与光合有效辐射（PAR）关系密切，复相关系数达到了0．9；冬小麦冠层荧光光谱在760nm和688nm波段的荧光大小基本相等，而地锦冠层荧光光谱在688nm波段的荧光强度是760nm的3倍左右，表明荧光光谱能够更加敏感地反映植被物种或生理生化状况的差别。最后，将夫琅和费暗线方法计算的688nm和760nm波段的荧光数据与激光脉冲调制荧光仪测定Fv／Fm荧光参数进行了统计分析，结果表明它与Fv／Fm存在极显著的负相关关系。所以利用夫琅和费暗线方法能够探测植被冠层荧光，并有可能替代传统的测定方法，并推广到航空航天平台，实现荧光探测从接触式点测量方式到航空或卫星遥感大面积监测的技术飞越。     

Influence of Site and Source Dependent Ground Motion Scenarios on the Seismic Safety of Long-span Bridges in Cologne, Germany

An overlap in frequency between the 1D resonance frequency of sediments and the vibrational frequencies of long-span bridges might lead to a strongly increased structural response of the latter. Interference of surface waves caused by reflections at dipping interfaces may introduce additional unfavourable amplifications. Therefore, the vulnerability of two bridges crossing the Rhine River in Cologne, Germany, was assessed using ground motion scenarios computed for four profiles crossing the Lower Rhine Embayment. Due to their vibrational frequencies being in the vicinity of resonant peaks in the response spectra, the Severinsbridge showed critical loading and the bridge Cologne-Deutz even exhibited grave failure according to the dynamic FE-simulations.     

Fast ion conduction character and ionic phase-transitions in disordered crystals: the complex case of the minerals of the pearceite–polybasite group

The minerals of the pearceite–polybasite group, general formula (Ag,Cu)₁₆ M ₂S₁₁ with M = Sb, As, have been recently structurally characterized. On the whole, all the structures can be described as a regular succession of two module layers stacked along the c axis: a first module layer (labeled A), with general composition [(Ag,Cu)₆(As,Sb)₂S₇]²⁻, and a second module layer (labeled B), with general composition [Ag₉CuS₄]²⁺. In detail, in the B layer of the pearceite structure silver cations are found in various sites corresponding to the most pronounced probability density function locations of diffusion-like paths. We have shown for the first time that the observed structural disorder in the B layer is strongly related to the fast ion conduction character exhibited by these minerals. This paper reports an integrated XREF, DSC, CIS and EPMA study on all the members of the pearceite–polybasite group. DSC and conductivity measurements pointed out that the 222 members show ionic-transitions at 340 K (arsenpolybasite-222) and 350 K (polybasite-222), whereas the 221 members have transitions at lower temperature, that is, 310–330 K (arsenpolybasite-221) and 335 K (polybasite-221). For the 111 members (pearceite and antimonpearceite), the transition occurs below room temperature at 273 K. In situ single-crystal X-ray diffraction experiments showed that these minerals present the same high temperature structure and are observed at room temperature either in their high temperature (HT) fast ion conductivity form or in one of the low temperature (LT) fully ordered (222), partially ordered (221) or still disordered (111) forms, with transition temperatures slightly above or below room temperature. The pearceite–polybasite group of minerals can be considered as a homogeneous series with the same aristotype, fast ion conducting form at high temperature. Depending upon the Cu content, an ordering occurs with transition temperatures related to that content: the lower the Cu content, the higher the transition temperature from the fast ion conducting HT form to the non-ion conducting form.Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.