"后Urey模型时代"的稳定同位素地球化学基础理论

简要综述了最近十几争来稳定同位素地球化学基础理论发展的几个热点,包括能处理重元素的同位素分馏的核场效应理论、基于晶格动力学及声子的密度函数微扰理论计算的固体同位素分馏理论、稳定同位素的微观反应动力学理论,以及含压力变量的同位素分馏理论。这些新理论,表明长期基于Urey模型或称Bigeleisen-Mayer公式的稳定同位素地球化学的时代已经结束,更精确、更丰富的理论体系正在逐步建立之中。     

Selection of p–y curves for the design of single laterally loaded piles

Two-dimensional finite element analysis has been used to find load–transfer relationships for translation of an infinitely long pile through undrained soil for a variety of soil-constitutive models. It has been shown that these load–transfer curves can be used as p–y curves in the analysis of single piles undergoing lateral pile head loading in undrained soils with non-linear stress–strain laws. Lateral pile response deduced from 2-D analysis input to the subgrade reaction method has been compared to the behaviour of a single pile analysed using three-dimensional finite element analysis. Good agreement between the two methods for non-linear soils suggests that the 2-D analysis may form a useful design method for calculation of p–y curves. Copyright © 1999 John Wiley & Sons, Ltd.     

Impact Factors on Removal of Perchloroethylene with Nano-Ni/Fe Methodology

Chlorinated hydrocarbons are widely detected in groundwater, but conventional removal methodologies are not time-and-cost effective. With the development of iron reducing technology in recent years, research on nano-iron and nano-bimetal has become a hot spot. The paper presents the results of impact factors on perchloroethylene （PCE） removal by nano-Ni/Fe method. The data show that the reaction rate of unexposed nano-Ni/Fe is 4 times higher than exposed one; and temperature is one of the important controlling factors. Reaction rate constant KSA increases by 2-3 times with every 10℃ increment of temperature. Within a specific range, higher Ni/Fe ratio favors dechlorination process. When the Ni/Fe is 8%, the dechlorination process reaches the highest rate. Dissoved oxygen in the solution does not favor the degradation of chlorinated hydrocarbons.     

大型城市管网抗震可靠性分析与优化

本文提出了地震作用下供水系统的渗漏模型,发展了地震后带渗漏管网的流分析技术,结合一次二阶矩方法获得了地震后供水管网的功能可靠度。针对供燃气管网系统则提出了一类高效精确的大型网络抗震连通可靠度分析的概率解析算法———递推分解算法。以上述管网抗震可靠性分析理论为基础,分别发展了基于模拟退火算法的供水系统网络拓扑优化分析理论和基于遗传算法的供燃气网络系统拓扑优化理论。     

Mineral Phase Transformation and Water Fluid Evolution of Khondalite Series in the Border Area of Shanxi and Inner Mongolia, China

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A study on the reaction kinetics of mineral surface adsorption in mix system

The experimental results on adsorption of ions pb²⁺, Zn²⁺ and Ag⁺ onto mineral surfaces in a mix system show that the reaction kinetics of adions adsorbed onto mineral surfaces was mainly controlled by their diffusion rates in solution. The concentration variations can be fit for the second-order rate equation with good determined coefficients r = 0.800 5—0.979 7. In the near neutral solution, the concentration of exchanged ions K⁺ and Na⁺ related to reaction time can be described by the fint-order rate equation with r = 0.855 7–0.997 7. Meanwhile, the complex diffusionexchange rate equation is suitable for describing the ca^{2 +} concentration variation, as ions Pb^{2 +} and Zn²⁺ were adions. Experimental data show that the amount of ions K⁺, Na⁺and Ca²⁺ release is much more than that of adion decrement in solution. This fact may suggest that the complexstion reaction of adions Pb²⁺, Z²⁺ and Ag⁺ with the mineral surfaces was the major reaction process while adions were not entering the phyllosilicate interlayers or CaCO₃ lattice to exchange the ions K⁺, Na⁺ and Ca²⁺ at room temperature. Project supported by the National Natural Science Foundation of China (Grant No. 49773206) and the Natural Science Foundation of Guangdong Province (Grant No. 960504)     

Generation of rhyolite magmas by melting of subducting sediments in Shodo-Shima island, Southwest Japan, and its bearing on the origin of high-Mg andesites

Abstract Geochemical characteristics of rhyolites from the Miocene Setouchi volcanic belt in the Southwest Japan arc were examined. The following observations may be best explained by the derivation of rhyolite magmas by melting of subducting sediments as follows. (i) Sr-Nd-Pb isotope compositions of Setouchi rhyolites are close to those of the local trench-fill sediments; (ii) major element compositions of rhyolites are identical to those of experimentally produced sediment melts; and (iii) concentrations of incompatible elements in rhyolites are consistent with partial melting of the local trench-fill sediments in the presence of residual garnet. Furthermore, trace element and isotope signatures of Setouchi high-Mg andesites can be also rationalized by interaction of such rhyolitic sediment melts with overlying mantle peridotites.     

基于小比例缩尺模型结构试验的小型钢架反力墙优化设计与力学性能分析

为了降低模型制作加工成本和节约试验空间,开展结构缩尺比例小于1:10的小模型结构抗震试验。目前,国内相关的试验设备较少,本文将参考大型反力墙的结构形式,研究小型钢架反力墙,并对其进行优化设计和力学性能分析,为后续的制作加工提供理论依据。     

强震下高层建筑横向晃动反应过程模拟分析

传统的静力弹塑性分析方法对强震作用下的高层建筑的横向晃动反应过程模拟时,存在计算结果不准确、计算用时较长的问题。提出新的强震下高层建筑横向晃动反应过程模拟分析方法,其基于直接积分法的三种方法实施模拟分析。分别是隐式方法、显式方法以及KK模型方法。其中隐式方法和显式方法均能够对不同自由度下的高层建筑的横向晃动位移作出准确的计算,KK模型通过高层建筑Von Mises屈服面,分析高层建筑钢材Bauschinger反应基础上,精确模拟出高层建筑在横向晃动反应中的变形过程。实验结果说明,所提方法对强震作用下的高层建筑的横向晃动反应的运算准确率和效率较高。     

Analytical design of an underwater construction robot on the slope with an up-cutting mode operation of a cutter bar

In this paper, the movements of the analytical models of complete underwater tracked vehicle (UTV) and cutter bar (CB) tool systems on a surface as well as their movements up and down a slope in the up-cutting mode operation are fully studied and analyzed. First, the mathematical expression of the mechanics, for which the forces, moments, and energy from the CB to the UTV are analyzed, is related. Next, analyses on the systemic parameters and their sensitivity are conducted to observe the variations of the operational and geometric parameters, as well as the cutter-tool and material-condition effects on the force, moment, and power components. Also, a design process composed of seven typical steps is proposed as the reference of a trencher-machine design. The important design parameters of the trenching machine such as the length of the CB, the nose radius of the CB, and the height of the pivot point are designed according to the proposed design process; furthermore, these parameters are used for the estimation of the slope-angle range when the trencher system is working on the slope. To demonstrate the application of derived equations to practical problems of the machine design, a number of numerical simulations are performed. Through the numerical simulations, the important parameters of the system such as the tangential force, F_t, the tractive thrust, H, the normal reaction, V, the cutting moment, M_c, the maximum carrier weight, W, and the available power are analyzed. From these, as a reference data for the designing of a trencher machine, the previous design of the system can be improved.