非充填复垦土壤饱和导水率预报的岭回归模型

运用统计软件SAS9.0,运用岭回归技术,对非充填复垦土壤的饱和导水率与土壤紧实度、土壤有机质含量、非毛管孔隙度、毛管孔隙度、容重、水稳性团聚体含量间的关系作了详细研究,并建立了饱和导水率的岭回归预测模型。结果表明,土壤饱和导水率与容重、紧实度、毛管孔隙度、非毛管孔隙度、有机质含量、水稳性团聚体含量之间存在着严重的多重共线性问题,各因子对饱和导水率的作用依次为非毛管孔隙度>紧实度>容重>有机质含量>毛管孔隙度>水稳性团聚体含量。该模型对研究充填复垦土壤的饱和导水率具有重要意义。

DYNAMIC STRESS INTENSITY FACTORS AROUND TWO CRACKS NEAR AN INTERFACE OF TWO DISSIMILAR ELASTIC HALF－PLANES UNDER IN－PLANE SHEAR IMPACT LOAD

Transient stresses around two collinear cracks which lie in parallel with theinterface of the two dissimilar half-planes are studied in this article.The surfaces ofthe cracks are sheared suddenly. Application of the Fourier and Laplace transforms technique reduces the problem to that of solving dual integrai equations.To solvethese,the differences of.the crack surface displacements are expanded in a series offunctions which are automatically zero outside of the cracks. The unknown coefficients accompanied in the series are determined by the Schmidt method. The stress intensity .factors are defined in the Laplace transform domain and these are inverted numerically in the physical space .As an example ,the dynamic stress intensity factors around two cracks in a ceramic and steel bonded composite are numerically calculated.

城镇土地定级因素选择研究

在完成宜宾市城区土地定级基础上 ,采用计量经济学方法分析发现因子间存在多重共线性 ,彼此间信息重叠 ,进而通过删掉一些因子办法修正多重共线性。研究结果表明 ,城镇土地定级并非选择因素因子越多越好 ,选择对土地质量影响重要因子 ,剔除影响不大因子并且相关性较高因子 ,既能克服因子间共线性 ,又能减少近一半工作量 。