江苏省宁镇扬山地丘陵地区农业资源的综合开发利用

宁镇扬山地丘陵地区土地面积133.9万公顷,农业资源丰富,是江苏省开发潜力很大的地区之一。本文从气候资源、水资源、土地资源和生物资源,阐述了它们的区域优势;探讨了农业资源开发利用中的主要问题。提出了综合开发利用的建议和对策,制定农业资源综合开发的总体规划;建立农业资源综合开发治理试验区;发挥山丘地区资源优势,建立商品生产基地。     

陕西灞源地区金矿勘查预测准则及找矿方向

本文以陕西灞源地区湘子岔与安岭沟两个金矿床以及小秦岭其它地区典型金矿床的成矿地质特征和控矿地质因素研究为基础,提出了本区金矿勘查预测的若干准则,并依据上述准则对不同区段的找矿远景进行综合评价,从而确定出该区今后进一步找矿的方向。     

Using Q-mode factor analysis in biostratigraphic ordination

Although traditionally restricted to the analysis of closed compositional data, the Imbrie Q-mode method appears also to be of utility when applied to binary data sets common in biostratigraphy. Its advantages include its utilization of the tally concept, and its ability to analyze very large numbers of species simultaneously. When the structure of the data set is simple, the method appears to be capable of ranking samples along a temporal gradient, or coenocline, defined by the second unroated factor. Varimax and oblique rotations do not appear to increase the efficacy of this ranking. Even when facies effects are important, a temporal ranking of samples can be achieved, providing that the variation due to time is greater than that due to facies.     

Simulation of one-dimensional correlated fields using a matrix-factorization moving average approach

The simulation of one-dimensional stationary correlated fields is of increasing importance in the earth sciences. A new method for repeated generation of independent realizations, which are long and dense relative to the correlation scale of the underlying stochastic process, is examined here. This method is conceptually simple and easy to apply. It consists of a matrix-factorization technique for derivation of moving average coefficients which are used as weights in the construction of successive observations from linear combinations of random normal deviates. The matrix-factorization procedure is fast and need be performed only once for a given correlation function and density of observations. This technique can be used to generate evenly spaced observations in time or a single space dimension for any prescribed correlation function and marginal distribution which is Gaussian with arbitrary mean and variance. Tests of ensemble properties of generation procedures have been developed and results for this method compared with those for a popular generation technique. For correlation functions and generation conditions examined, the matrix-factorization moving average approach more accurately produces ensemble characteristics of the prescribed underlying process. For repeated generation of 2001 observations spaced evenly over realizations with length equal to 100 times the correlation scale, the moving average approach requires only about one fifth the CPU time used by the Shinozuka and Jan method to obtain similar accuracy.     

判定潜在震源区的活断层模糊综合评判模型

确定潜在震源区及其震级上限是地震区划工作中的重要一环,而活断层的研究在这一领域中具有重要的意义。本文采用概率数理统计和模糊数学方法建立了活断层模糊综合评判模型,对活断层的定量化研究、潜在震源区研究中的不确定性分析以及充分反映地震活动的时空不均一性方面作了初步的探索性研究。并以华北地区为例进行了试算,取得了较好的结果     

Complex rays applied to wave propagation in a viscoelastic medium

In order to trace a ray between known source and receiver locations in a perfectly elastic medium, the take-off angle must be determined, or equialently, the ray parameter. In a viscoelastic medium, the initial value of a second angle, the attenuation angle (the angle between the normal to the plane wavefront and the direction of maximum attenuation), must also be determined. There seems to be no agreement in the literature as to how this should be done. In computing anelastic synthetic seismograms, some authors have simply chosen arbitrary numerical values for the initial attenuation angle, resulting in different raypaths for different choices. There exists, however, a procedure in which the arbitrariness is not present, i.e., in which the raypath is uniquely determined. It consists of computing the value of the anelastic ray parameter for which the phase function is stationary (Fermat's principle). This unique value of the ray parameter gives unique values for the take-off and attenuation angles. The coordinates of points on these stationary raypaths are complex numbers. Such rays are known as complex rays. They have been used to study electromagnetic wave propagation in lossy media. However, ray-synthetic seismograms can be computed by this procedure without concern for the details of complex raypath coordinates. To clarify the nature of complex rays, we study two examples involving a ray passing through a vertically inhomogeneous medium. In the first example, the medium consists of a sequence of discrete homogeneous layers. We find that the coordinates of points on the ray are generally complex (other than the source and receiver points which are usually assumed to lie in real space), except for a ray which is symmetric about an axis down its center, in which case the center point of the ray lies in real space. In the second example, the velocity varies continuously and linearly with depth. We show that, in geneneral, the turning point of the ray lies in complex space (unlike the symmetric ray in the discrete layer case), except if the ratio of the velocity gradient to the complex frequency-dependent velocity at the surface is a real number. We also present a numerical example which demonstrates that the differences between parameters, such as arrival time and raypath angles, for the stationary ray and for rays computed by the above-mentioned arbitrary approaches can be substantial.