边坡稳定分析的三维Spencer法

将边坡稳定分析中的二维Spencer法拓展到了三维。该方法对所有条块满足力的平衡以及整体力矩平衡，克服了其他方法中只适用对称问题的缺点，不需已知滑动方向，还可根据滑面的几何特征，进一步得到各条块局部的稳定性系数及其潜在的滑动方向。此外，给出了该方法的实现步骤，其算法的收敛性也较好。最后以不对称问题为算例，并与其他文献中的结果进行比较，验证了该方法的可行性和有效性。

Search For Critical Slip Surface In Slope Stability Analysis By Spline-Based Ga Method

The stability of a soil slope is usually analyzed by limit equilibrium methods, in which the identification of the critical slip surface is of principal importance. In this study the spline curve in conjunction with a genetic algorithm is used to search the critical slip surface, and Spencer's method is employed to calculate the factor of safety. Three examples are presented to illustrate the reliability and efficiency of the method. Slip surfaces defined by a series of straight lines are compared with those defined by spline curves, and the results indicate that use of spline curves renders better results for a given number of slip surface nodal points comparing with the approximation using straight line segments.

A paradigm for virus-host coevolution: Sequential counter-adaptations between endogenous and exogenous retroviruses

Endogenous retroviruses ( ERVs) are remnants of ancient retroviral infections of the host germline transmitted vertically from generation to generation. It is hypothesized that some ERVs are used by the host as restriction factors to block the infection o

Influence of methanol on retention of hydrophobic organic chemicals in soil leaching column chromatography

The influence of methanol in methanol-water mixed eluents on the capacity factor (P), an important parameter which could depict leaching potential of hydrophobic organic chemicals (HOCs) in soil leaching column chromatography (SLCC), was investigated. Two reference soils, GSE 17201 obtained from Bayer Landwirtschaftszentrum, Monheim, Germany and SP 14696 from LUFA, Spencer, Germany, were used as packing materials in soil columns, and isocratic elution with methanol-water mixtures at different volume fractions of methanol (phi) were tested. Shortterm exposure of the column (packed with the GSE 17201 soil) to the eluents increased solute retention by a certain (23% log-unit) degree evaluated through a correlation with the retention on the same soil column but unpreconditioned by methanol-containing eluents. Long-term exposure of soil columns to the eluents did not influence the solute retention. A log-linear equation, log k' = log k'(w) - Sphi, could well and generally describe the retention of HOCs in SLCC. For the compounds of homologous series, logk'(w), had good linear relationship with S, indicating the hydrophobic partition mechanism existing in the retention process. (C) 2002 Elsevier Science Ltd. All rights reserved.

管理干部胜任特征评价方法的初步研究

Competency Assessment Method (CAM) is an important technique of Human Resource Management and Development in theory and practice, especially in personnel selection and training. Based on literatures of related fields, the thesis explored the feasibility of CAM in China. The main results found in this study are as follows: 1. Competencies scored in Behavioral Event Interviews (BEI) are not influenced by length of protocol, by performance in the preceding year. Average level and maximal level of complexity correlate significantly with length of protocol. Total competency frequency of outstanding executives is not significantly different from that of typical executives. These results support McCleland's view. But there is significant correlation between length of protocol and competency frequencies, which which is not agreed by McCleland. We found that competency scores using coding standard of average level and maximal level of complexity show more reliability than that using coding standard of competency frequencies. But this isn't confirmed by McCleland. 2. Inter-rater reliability was studied. The results indicated: total Category Agreement (CA) is 55.45%, over 70 percent of 20 competencies of the inter-rater reliability coefficients based on the classical test theory are significantly correlated. G coefficient based on the generalization theory is 0.85697. 3. Study of criterion sample shows that manager's competencies of China's communication enterprise are as follows: Impact and Influence, Organization Commitment, Information Seeking, Achievement Orientation, Team Leadership, Interpersonal Understanding, Initiative, Market Awareness, Self-confidence, Developing Others. This result in similar to the generic competency model of managers presented in Spencer's book. 4. CAM showed more advantages than the method of experts panel judgement.