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.     

数值试验中时间步长的选取

建立一个二维的海陆风静力模式来讨论时间步长的选取，发现定时间步长不宜取得太大或者太小，必须是某个适当的值。变时间步长的模拟效果要比定步长理想。时间步长越大，海风中心强度模拟值变小。     

大同镇川堡井水位阶变与地震关系初析

统计了大同镇川堡井１９８８年６月～１９９１年１２月原始记录曲线的水位阶变资料，认为该井水位阶变可能反映了口泉断裂的蠕动，也反映了两次大同—阳高地震前应力应变作用的过程。     

印尼苏门答腊8.7级大震对中国陆区的影响

发生在2004年12月26日的印尼苏门答腊8．7级地震，是全球有地震台网以来100多年中记录到的少数几次特大地震之一。初步汇集了在中国陆区观测到的地震活动、地壳形变、地下流体等多学科震时和震后效应的异常变化，包括地震活动性（特别是云南地区）的显著增强；地壳形变观测，尤其是钻孔应变观测记录到地壳应力-应变的震时和震后显著变化，以及地下水温度、化学成分、特别是水位的突出变化。同时，还从库仑破裂应力触发、动态应力触发以及下地壳和上地幔流动变形机制等方面，对这些大震效应作了一些成因机理讨论。     

动力刚度计算方法-"盐溶”法-的改进

本文首先讨论了采用盐溶法（damping-solvent extraction method)争动力刚度时，在某些频率点（奇点）产生误差的原因；提出一种多次逼近的改进办法，提高了计算精度。在一般情况下，动力刚度的奇点是未知的。本文建议的逼近技术可用于校核这一方法所获得的结果。     

东安牛头寨地区锑矿床控制因素及成因探讨

锑矿床严格受构造控制，表现出逐级控矿特征：区域性F1断裂、牛头寨复式背斜及北北东、北北西、北西向次级断裂，分别控制着锑矿带、锑矿床的空间展布及锑矿脉的形态、产状与规模。地层岩石建造对成矿的控制，主要表现在赋矿地层中的白云岩、硅质岩等易碎裂，为矿液的运移提供了有利的通道。部分含矿地层的Sb高丰度，还可能成为矿提供了矿源。已有的研究表明，锑矿床的硫同位素组成具有岩浆硫特征，并混入了部分围岩沉积硫。石英的氢氧同位素组成反映出岩浆流体与变质水混入溶液特征。矿物包裹体的爆裂温度平均为157℃。石英的包裹体成分测试结果，揭示了矿液为K－Na-Ca-Cl型富硅的弱碱性溶液。矿床成因厘定为岩浆期后中低温热液脉状充填矿床。     

Inversion of coseismic stress-triggered fault slips using borehole strainmeter observations

Coseismic stress-triggering is becoming a new hot spot of research. Coseismic strain steps recorded by borehole strainmeters are particularly valuable in studying coseismic stress-triggered fault slips. Based on the theory of dis location, one can invert the triggered fault slips with such data if he/she has a well understanding about the local faults. Genetic algorithm can be applied to significantly raise the efficiency of searching a best solution among all possibilities in this kind of inversion. A testifying check of the program and analyses of each parameter＇s influence may further enhance the reliability of inversion results. Taking complexity of geological structure into account, the inversion results should be regarded as the predominant property or a comprehensive effect of triggered local faults＇ activities. As an attempt, we inverted the assumingly active faults＇ slips triggered by the Ms=8.1 Kunlun Mountain earthquake over Beijing area.     

任意色阶区间精细选区创建方法初探

在通道中利用“阂值”命令创建选择X-255。在通道混合中创建任意色阶区间选择X1～X2。利用通道混合“减去”模式中“缩放”“补偿值”实现深度自由选择。     

经济信息管理系统分析与研究

根据经济信息管理系统的组织特征与建立原则 ,提出经济信息管理系统的结构模式与建立步骤。