scholarly journals Analytic Representation of the Optimal Flow for Gravity Irrigation

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2710 ◽  
Author(s):  
Carlos Fuentes ◽  
Carlos Chávez
Keyword(s):  
Linear Relationship ◽  
Analytic Representation ◽  
Hydrodynamic Characteristics ◽  
One Dimensional ◽  
Coupled Equations ◽  
Irrigation Flow ◽  
Coefficient Of Uniformity ◽  
Relationship Of ◽  
Strip Length ◽  
Infiltration Parameters

The aim of this study is the deduction of an analytic representation of the optimal irrigation flow depending on the border length, hydrodynamic properties, and soil moisture constants, with high values of the coefficient of uniformity. In order not to be limited to the simplified models, the linear relationship of the numerical simulation with the hydrodynamic model, formed by the coupled equations of Barré de Saint-Venant and Richards, was established. Sample records for 10 soil types of contrasting texture were used and were applied to three water depths. On the other hand, the analytical representation of the linear relationship using the Parlange theory of infiltration proposed for integrating the differential equation of one-dimensional vertical infiltration was established. The obtained formula for calculating the optimal unitary discharge is a function of the border strip length, the net depth, the characteristic infiltration parameters (capillary forces, sorptivity, and gravitational forces), the saturated hydraulic conductivity, and a shape parameter of the hydrodynamic characteristics. The good accordance between the numerical and analytical results allows us to recommend the formula for the design of gravity irrigation.

scholarly journals One-Dimensional Vacuum Steady Seepage Model of Unsaturated Soil and Finite Difference Solution

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Feng Huang ◽  
Jianguo Lyu ◽  
Guihe Wang ◽  
Hongyan Liu
Keyword(s):  
Finite Difference ◽  
Unsaturated Soil ◽  
Vacuum Pressure ◽  
Vacuum Field ◽  
One Dimensional ◽  
Steady Seepage ◽  
Basic Equations ◽  
The One ◽  
Seepage Law ◽  
Relationship Of

Vacuum tube dewatering method and light well point method have been widely used in engineering dewatering and foundation treatment. However, there is little research on the calculation method of unsaturated seepage under the effect of vacuum pressure which is generated by the vacuum well. In view of this, the one-dimensional (1D) steady seepage law of unsaturated soil in vacuum field has been analyzed based on Darcy’s law, basic equations, and finite difference method. First, the gravity drainage ability is analyzed. The analysis presents that much unsaturated water can not be drained off only by gravity effect because of surface tension. Second, the unsaturated vacuum seepage equations are built up in conditions of flux boundary and waterhead boundary. Finally, two examples are analyzed based on the relationship of matric suction and permeability coefficient after boundary conditions are determined. The results show that vacuum pressure will significantly enhance the drainage ability of unsaturated water by improving the hydraulic gradient of unsaturated water.

scholarly journals Estimation for Two-Dimensional Nonsymmetric Coherently Distributed Source in L-Shaped Arrays

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Tao Wu ◽  
Zhenghong Deng ◽  
Qingyue Gu ◽  
Jiwei Xu
Keyword(s):  
Expectation Maximization ◽  
Two Dimensional ◽  
Signal Distribution ◽  
Distributed Source ◽  
One Dimensional ◽  
Least Squares Estimators ◽  
Iterative Calculation ◽  
Symmetric Source ◽  
Relationship Of ◽  
The Relationship

We explore the estimation of a two-dimensional (2D) nonsymmetric coherently distributed (CD) source using L-shaped arrays. Compared with a symmetric source, the modeling and estimation of a nonsymmetric source are more practical. A nonsymmetric CD source is established through modeling the deterministic angular signal distribution function as a summation of Gaussian probability density functions. Parameter estimation of the nonsymmetric distributed source is proposed under an expectation maximization (EM) framework. The proposed EM iterative calculation contains three steps in each cycle. Firstly, the nominal azimuth angles and nominal elevation angles of Gaussian components in the nonsymmetric source are obtained from the relationship of rotational invariance matrices. Then, angular spreads can be solved through one-dimensional (1D) searching based on nominal angles. Finally, the powers of Gaussian components are obtained by solving least-squares estimators. Simulations are conducted to verify the effectiveness of the nonsymmetric CD model and estimation technique.

scholarly journals Non-linear relationship of cell hit and transformation probabilities in a low dose of inhaled radon progenies

2009 ◽  
Vol 29 (2) ◽  
pp. 147-162 ◽  
Author(s):  
Imre Balásházy ◽  
Árpád Farkas ◽  
Balázs Gergely Madas ◽  
Werner Hofmann
Keyword(s):  
Linear Relationship ◽  
Low Dose ◽  
Non Linear ◽  
Relationship Of

Measurement of Press Creep Stress Exponent of ZM6 Alloy at Room Temperature

2007 ◽  
Vol 546-549 ◽  
pp. 509-511
Author(s):  
Ying Ying Zhong ◽  
Shu Fang Xu ◽  
Xin Ming Zhang ◽  
Tian Cai Guo ◽  
Yun Lai Deng
Keyword(s):  
Strain Rate ◽  
Linear Relationship ◽  
Stress Exponent ◽  
Room Temperature ◽  
Constant Load ◽  
Nano Indentation ◽  
Indentation Technique ◽  
Creep Stress ◽  
Creep Stress Exponent ◽  
Relationship Of

Nano-indentation technique was used to survey creep stress exponent of ZM6 (Mg-2.8Nd-0.7Zn-0.6Zr) alloy at room temperature. The results showed that average press creep stress exponent of ZM6 alloy was about 89.75, and independent of strain rate and hardness, which has been verified by linear relationship of the double logarithmic plots between strain rate ( ε& ) and hardness (H ) measured by a nano-indentation equipment with constant load of 500mN.

The Comparison and Analysis of Void Fraction of OGFC-13 Asphalt Concrete through Vacuum Method and Volume Method

2016 ◽  
Vol 847 ◽  
pp. 17-24 ◽  
Author(s):  
Cheng Yang Tang ◽  
Wen Yi ◽  
Xian Feng He ◽  
Li Tan
Keyword(s):  
Linear Relationship ◽  
Void Fraction ◽  
Asphalt Mixture ◽  
Hunan Province ◽  
Pass Rate ◽  
Mixture Ratio ◽  
Vacuum Method ◽  
Comparison And Analysis ◽  
Volume Method ◽  
Relationship Of

In this paper, the mixture ratio experiment has been done about OGFC-13 asphalt mixture of the layer on S103(liuyang section) of Changsha, Hunan province The void fraction of asphalt mixture is determined by vacuum sealing method and volume method on the condition of different material and different gradation. Through the comparison and analysis of void fraction determined values by vacuum method and volume method, it can been found that the air porosity of OGFC-13 asphalt mixture has a good linear relationship with the 2.36mm pass rate. The linear relationship of void fraction determined value by vacuum method and volume method relates with materials and nominal diameter.

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