1990—1995年全球灾害地震统计特征

研究了１９９０－１９９５年间全球大地震活动及重大灾害地震的时空强分布特征,着重讨论了灾害地震与地震活动水平,人文地理,经济地理和发震时间等各种因素的密切关系。     

Variogram Fitting by Generalized Least Squares Using an Explicit Formula for the Covariance Structure

In the context of spatial statistics, the classical variogram estimator proposed by Matheron can be written as a quadratic form of the observations. If data are Gaussian with constant mean, then the correlation between the classical variogram estimator at two different lags is a function of the spatial design matrix and the variance matrix. When data are independent with unidimensional and regular support, an explicit formula for this correlation is available. The same is true for a multidimensional and regular support as can be shown by using Kronecker products of matrices. As variogram fitting is a crucial stage for correct spatial prediction, it is proposed to use a generalized least squares method with an explicit formula for the covariance structure (GLSE). A good approximation of the covariance structure is achieved by taking account of the explicit formula for the correlation in the independent situation. Simulations are carried out with several types of underlying variograms, as well as with outliers in the data. Results show that this technique (GLSE), combined with a robust estimator of the variogram, improves the fit significantly.     

A Comparison of the Sequential Gaussian and Markov-Bayes Simulation Methods for Small Samples

We compared the performance of sequential Gaussian simulation (sGs) and Markov-Bayes simulation (MBs) using relatively small samples taken from synthetic datasets. A moderate correlation (approximately r = 0.70) existed between a continuous primary variable and a continuous secondary variable. Given the small sample sizes, our objective was to determine whether MBs, with its ability to incorporate the secondary information, would prove superior to SgS. A split-split-plot computer experiment was conducted to compare the two simulation methods over a variety of primary and secondary sample sizes as well as spatial correlations. Using average mean square prediction error as a measure of local performance, sGs and MBs were roughly equivalent for random fields with short ranges (2 m). As range increased (15 m) the average mean square prediction error for sGs was less than or equal to that for MBs, even when number of noncollocated secondary observations was twice the number of collocated observations. Median variance within nonoverlapping subregions was used as a measure of the local heterogeneity or surface texture of the image. In most situations sGs images more faithfully reflected the true local heterogeneity, while MBs was more erratic, sometimes oversmoothing and sometimes undersmoothing.     

粗粒土动强度试验成果的分析方法

介绍一种新的粗粒土动强度试验成果的分析整理方法。在对试验所获资料进行误差分析的基础上,认为这种方法可为工程设计的可靠性分析提供方便和依据,同时,也有效地弱化资料分析整理过程中的人为因素。     

东南沿海地震带b值统计

本文讨论可信的历史地震资料和现代化仪器记录资料的统一使用问题。     

Variance and skewness in the FIRST survey

We investigate the large-scale clustering of radio sources in the FIRST 1.4-GHz survey by analysing the distribution function ( counts in cells ). We select a reliable sample from the the FIRST catalogue, paying particular attention to the problem of how to define single radio sources from the multiple components listed. We also consider the incompleteness of the catalogue. We estimate the angular two-point correlation function w (θ), the variance Ψ₂ and skewness Ψ₃ of the distribution for the various subsamples chosen on different criteria. Both w (θ) and Ψ₂ show power-law behaviour with an amplitude corresponding to a spatial correlation length of r ₀ ∼ 10  h ⁻¹Mpc. We detect significant skewness in the distribution, the first such detection in radio surveys. This skewness is found to be related to the variance through Ψ₃ =  S ₃(Ψ₂)^α, with α = 1.9 ± 0.1, consistent with the non-linear gravitational growth of perturbations from primordial Gaussian initial conditions. We show that the amplitude of variance and the skewness are consistent with realistic models of galaxy clustering.     

The contribution to the Galactic diffuse gamma-ray spectrum from unresolved rotation-powered pulsars

We consider the contribution to the Galactic diffuse γ-ray emission from unresolved γ-ray pulsars. Based on the thick outer gap model, Monte Carlo methods are used to simulate the properties (period, distance, magnetic field, etc.) of the Galactic population of rotation-powered pulsars the gamma-ray flux of which is lower than the threshold sensitivity of the EGRET detector on the Compton Gamma-Ray Observatory . Furthermore, the contribution to the Galactic diffuse γ-ray spectrum from the unresolved γ-ray pulsars is calculated. Our results indicate that the unresolved γ-ray pulsars contribute ∼5 to ∼10 per cent to the measured Galactic diffuse γ-ray emission if the birth rate of neutron stars in the Galaxy is 1 to 2 per century, and that these pulsars contribute significantly to the observed Galactic diffuse γ-ray emission above 1 GeV. Comparing the model spectrum with the observed spectrum, we show that the unresolved γ-ray pulsars contribute very little to the diffuse emission at lower energies but can account for ∼50 per cent of the observed spectrum above 1 GeV if the product of the birth rate of neutron stars and the γ-ray beaming fraction is about unity. Such a large pulsar contribution can explain the difference (∼60 per cent) between the intensity of the Galactic diffuse emission as measured by EGRET above 1 GeV and model predictions based on cosmic ray–matter interaction only.     

运用双层控制体系确定风、涝灾区域保险费率研究——以河北省为例

灾害损失率计算是农作物保险费率确定的基础。确定为农作物保险费率服务的灾害损失率需要较强的稳定性，为此我们采用多年平均损失率指标，并利用多年平均损失率进行分区。它既能反映出灾害损失率宏观分布规律，又能刻划出灾害损失率较微观的空间分布差异，使区域费率确定更加准确、合理。由于研究区域灾情信息的不完全性，依据大系统理论的递阶控制原理，我们设计了多年平均损失率的双层控制体系，使区域费率的厘定实现了稳定性和灵活性的统一。     

极射赤平投影中的数学方法

本文提供了严格依据赤平投影原理并利用空间解析几何知识推导出的公式计算方法，可以写出已知产状的线或面的赤平投影方程，也能计算两线所共的面，两面的交线，线或面之间的夹角以及它们的平分线或平分面，可以进行真倾斜和视倾斜的换算，倾斜和侧伏的换算；模拟线面绕轴的旋转以及恢复节理的原始产状；最后阐述用计算机进行节理统计和绘制极点等密图的原理。所用的向量表示方法直观表达了相关构造要素之间的空间关系，可用于计算机辅助教学，也能用于生产实践，精度可达0.01°。     

基于地震活动性的强震中长期预报的三种新方法

本文介绍基于地震活动性的强震中长期预报的三种新方法，即自助统计，Ｓｏｍｐｉ谱分析及模糊时空分维。对川滇地区一些强震的震例分析检验结果表明，这三种新方法可在数年期的强震中长期预报中发挥一定的作用。