RETC各步骤简要说明
1、Type of Problem
Ur specifies identifying header for the output file and lects whether direct or inver problem is solved. The ur also has to specify which type of input data are available for inver procedure. Experimental hydraulic data need to be provided to solve the inver problem (i.e., optimization of parameters in hydraulic model). For the direct problem, RETC calculates the hydraulic functions from ur-specified model.
用户指定确认输出文件的标题，同时选择需要解决的直接或逆向的问题。用户还需要指定输入数据的类型以便开展逆向过程。需要提供实验水力数据来解决逆向问题（例如，水力模型中参数的最优化）。至于直接问题，RETC从用户指定的模型中计算水力函数。
2、Time and Space Units
勾股定理逆定理
Ur lects the length and time units for the data in the input and output files. When the units are changed, data in the input file are converted accordingly.
用户选择输入和输出文件中数据的长度和时间单位。当单位发生变化时，输入文件中的数据相应地发生变化。
One also specifies the maximum number of iterations (MIT) for the inver problem and maximum number of iterations (KITER) to be printed into the output file. U a large number (e.g., MIT=30) for the simultaneous fit. Improved estimates for the unknown coefficients are printed during the first KITER iterations of the least-squares analysis. This input parameter eliminates excessively long output files if many iterations are needed before convergence is reached. Results for the last iterations are always printed.
用户同样需要指定逆向问题中迭代的最大值（MIT），以及输出文件中迭代的最大值（KITER）。将两者同时设定为较大值（例如，MIT=30）。未知系数的矫正估计将在最小二乘分析的第1次KITER迭代时保存。如果在达到收敛之前需要很多次迭代，那么这个输入的参数将避免过长的输出文件。最后一次迭代的结果通常是输出的。
每月5号3、Type of Retention/Conductivity Model
The code allows urs to lect eight model combinations to describe the soil hydraulic properties.
荞麦拌面此界面允许用户选择8种模型组合来描述土壤水力特征。
For the retention data the models:
对于土壤水分特征数据（土壤持水性数据）：
word序号怎么自动生成a) van Genuchten [1980] with variable m and n,
b) van Genuchten [1980] with m = 1 - 1/n,
c) van Genuchten [1980] with m = 1 - 2/n,国家助学金申请理由200字>章程英文
d) Brooks and Corey [1964],
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e) Kosugi [1996] (log normal distribution model对数正态分布模型),
f) Dual-porosity model 双重孔隙度模型
For the conductivity data model a), b), d), e), and f) can be coupled with Mualem's model;
对于土壤导水率数据，模型a)、b)、d)、e)和f)可与Mualem模型联用；
a), c) and d) can be coupled with Burdine's Model
a)、c)和d)可与Burdine模型联用。
4、Hydraulic Parameter
身份证年龄公式The ur specifies the initial estimates for the model parameters and lects which parameters are unknown and fitted to the experimental data, and which are suppod to be known and kept constant. Initial estimates of the hydraulic parameters may also be lected from a soil catalog by specifying the soil texture. This approach has inherent errors; it is always the ur's reponsibility to evaluate the initial estimates in view of the optimization results. Finally, the ur can cho characteristic names for the model parameters. When the direct problem is solved, there are no fitted parameters, and the initial estimates are the values for which the forward problem is solved.
用户指定模型参数的初始估计值，并选择未知参数和适合的实验数据，以及被认为是已知的和常量的数据。水力参数的初始估计值还可通过指定土壤质地从土壤目录中选择获得。这种方法具有固有的误差；从最优化结果来看，估计初始值始终是用户的责任。最后，用户可以选择的模型参数的特征名称。当直接问题解决时，没有拟合参数，以及初始估计值的正向问题就解决了。
5、Retention Curve Data
Specifies obrved retention data. This window is ud to enter pairs of pressure head/suction and water content data as well as the weight of this retention point. A new pair of data is entered after clicking on a "Add Line" button. A pair of data is deleted by locating a cursor on a particular line and clicking button "Delete Line". RETC can also import a ur-specified ASCII input file.
指定土壤水分特征的观测数据。这个窗口用于输入成对的压力水头和土壤含水量数据，以及这一持水点的质量。点击“Add Line”按钮将增加一组数据。点击“Delete Line”按钮将删除光标指定的行。RETC还可导入用户指定的ASC Ⅱ输入文件。
6、Warning
7、RETC Guide
8、Results
8.1 Soil Hydraulic Properties
8.2 Output File
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