On Minerogenetic Series: The Third Discussion

The minerogenetic(or metallogenetic) series of mineral deposits(called minerogenetic series for short) is an academic idea(concept) of studying minerogenetic characteristics in mineral deposit geology. It uses the views of systematology and mobilism to study mineralizing processes and naturally occurring mineral deposit assemblages formed in various stages of geological development in specific tectonic environments. The minerogenetic series is also a natural classification of mineral deposits. T...     

基于假三元模型的透辉石-硬玉固溶体热力学性质计算

自然界中矿物多以固溶体形式存在,据其晶体化学特征计算热力学性质是开展矿物成因理论研究的基础。本文引入描述二元矿物固溶体热力学性质的假三元模型,计算得到了透辉石-硬玉固溶体系列的热力学性质。该模型通过构造一种高度有序的中间相,同时考虑长程和短程有序效应,基于热力学平衡态矿物固溶体自由能最低的规律,可以计算特定组分下矿物的平衡自由能、焓和熵等热力学参数。本文针对透辉石-硬玉固溶体体系,取绿辉石为其中间有序态,计算了其活度-成分关系和温度-组分相图等,发现绿辉石随温度升高的有序无序相变为一级相变,相变温度为1 148±25 K,与实验研究结果一致。本文获得的透辉石-绿辉石-硬玉体系的热力学参数可用于视剖面图方法研究MORB成分的岩石的榴辉岩相变质作用过程。     

高温高压模拟实验气态产物碳同位素演化特征

对泥炭、褐煤样品进行了高压（０．１～２ＧＰａ）、高温（２００～８００℃）模拟实验,并用微量气体同位素测定系统（ＧＣ－Ｃ－ＭＳ）测定了气态产物的碳同位素值。在４００℃的温度条件下,乙烷、丙烷、正丁烷碳同位素值有随压力升高而变重的趋势,并出现了碳同位素局部反序的特征（δ＾１３Ｃ２〉δ＾１３Ｃ３）;在６００℃、１ＧＰａ和１．５ＧＰａ的温压条件下,甲烷和乙烷的δ＾１３（ＰＤＢ）值偏重,分别约为－１５．０‰     

基于高阶滑模控制器的水下潜器运动控制

水下环境复杂多变,由于水流的不可预知性和多变性,潜器的水动力系数往往无法准确获取,使得依赖这种参数的潜器运动控制算法的应用受到了很大的局限。为了解决控制器对模型参数的依赖,设计了一种基于高阶滑模控制算法的模型无关控制器,并通过设置合理的过渡过程,解决了这种控制算法依赖初值的弊端。仿真结果表明,位置和姿态的控制能够快速的收敛,误差很小并且不依赖于初始条件,控制器需调节参数很少,并且算法简单,适用于工程的实际需要。     

Numerical analysis of the symmetric methods

Aimed at the initial value problem of the particular second-order ordinary differential equations,y =f(x, y), the symmetric methods (Quinlan and Tremaine, 1990) and our methods (Xu and Zhang, 1994) have been compared in detail by integrating the artificial earth satellite orbits in this paper. In the end, we point out clearly that the integral accuracy of numerical integration of the satellite orbits by applying our methods is obviously higher than that by applying the same order formula of the symmetric methods when the integration time-interval is not greater than 12000 periods.     

三维高阶深度偏移方程及其数值求解方法

从三维非均匀介质中的波动方程出发,利用拟微分算子理论,Ｐａｄｅ逼近方法及因式分解技巧,获得了非均匀介质的三维高阶深度偏移方程,相应地提出了逐次低阶方程方法、低阶方程组方法及分裂方法等３种求解方法．与二维情形不同,以上每一种方法在数值求解时均存在由测线坐标ｙ的出现而带来的困难．为了克服这一困难,我们提出了差分算子分解方法,避免了近年来人们竞相研究的ｘ－ｙ方向微分算子分裂带来的分裂误差,保持了应有的相容性,解决了这一令人烦恼的问题．     

Calculating actual crop evapotranspiration under soil water stress conditions with appropriate numerical methods and time step

Calculation of actual crop evapotranspiration under soil water stress conditions is crucial for hydrological modeling and irrigation water management. Results of actual evapotranspiration depend on the estimation of water stress coefficient from soil water storage in the root zone, which varies with numerical methods and time step used. During soil water depletion periods without irrigation or precipitation, the actual crop evapotranspiration can be calculated by an analytical method and various numerical methods. We compared the results from several commonly used numerical methods, including the explicit, implicit and modified Euler methods, the midpoint method, and the Heun's third‐order method, with results of the analytical method as the bench mark. Results indicate that relative errors of actual crop evapotranspiration calculated with numerical methods in one time step are independent of the initial soil water storage in the range of soil water stress. Absolute values of relative error decrease with the order of numerical methods. They also decrease with the number of time step, which can ensure the numerical stability of successive simulation of soil water balance. Considering the calculation complexity and calculation errors caused by numerical approximation for different time step and maximum crop evapotranspiration, the explicit Euler method is recommended for the time step of 1 day (d) or 2 d for maximum crop evapotranspiration less than 5 mm/d, the midpoint method or the modified Euler method for the time step of up to one week or 10 d for maximum crop evapotranspiration less than 5 mm/d, and the Heun's third‐order method for the time step of up to 15 d. Copyright © 2011 John Wiley & Sons, Ltd.     

关于广西大厂矿田民矿开采问题的探讨

文章讨论了民矿乱采滥挖所造成的严重的资源浪费、人生安全及社会治安等问题及其原因,探讨解决民矿开采问题的有效途径,以求引起各级政府和社会的重视。     

Impact of road‐generated storm runoff on a small catchment response

The impact of road‐generated runoff on the hydrological response of a zero‐order basin was monitored for a sequence of 24 storm events. The study was conducted in a zero‐order basin (C1; 0·5ha) with an unpaved mountain road; an adjacent unroaded zero‐order basin (C2; 0·2 ha) with similar topography and lithology was used to evaluate the hydrological behaviour of the affected zero‐order basin prior to construction of the road. The impact of the road at the zero‐order basin scale was highly dependent on the antecedent soil‐moisture conditions, total storm precipitation, and to some extent rainfall intensity. At the beginning of the monitoring period, during dry antecedent conditions, road runoff contributed 50% of the total runoff and 70% of the peak flow from the affected catchment (C1). The response from the unroaded catchment was almost insignificant during dry antecedent conditions. As soil moisture increased, the road exerted less influence on the total runoff from the roaded catchment. For very wet conditions, the influence of road‐generated runoff on total outflow from the roaded catchment diminished to only 5·4%. Both catchments, roaded and unroaded, produced equivalent amount of outflow during very wet antecedent conditions on a unit area basis. The lag time between the rainfall and runoff peaks observed in the unroaded catchment during the monitoring period ranged from 0 to 4 h depending on the amount of precipitation and antecedent conditions, owing mainly to much slower subsurface flow pathways in the unroaded zero‐order basin. In contrast, the lag time in the roaded zero‐order basin was virtually nil during all storms. Copyright © 2009 John Wiley & Sons, Ltd.     

Bifurcation and second‐order work in geomaterials

In this paper, the ability of a material rate‐independent system to evolve toward another mechanical state from an equilibrium configuration, with no change in the control parameters, is investigated. From a mechanical point of view, this means that the system can spontaneously develop kinetic energy with no external disturbance from an equilibrium state, which corresponds to a particular case of bifurcation. The existence of both conjugate incremental strain and stress such that the second‐order work vanishes is established as a necessary and sufficient condition for the appearance of this bifurcation phenomenon. It is proved that this fundamental result is independent of the constitutive relation of the rate‐independent material considered. Then the case of homogeneous loading paths is investigated, and, as an illustration, the subsequent results are applied to interpret the well‐known liquefaction observed under isochoric triaxial loading conditions with loose granular materials. Copyright © 2006 John Wiley & Sons, Ltd.