|
HYDRUS (software)
Hydrus is a suite of Windows-based modeling software that can be used for analysis of water flow, heat and solute transport in variably saturated porous media (e.g., soils). HYDRUS suite of software is supported by an interactive graphics-based interface for data-preprocessing, discretization of the soil profile, and graphic presentation of the results. While HYDRUS-1D simulates water flow, solute and heat transport in one-dimension, and is a public domain software, HYDRUS 2D/3D extends the simulation capabilities to the second and third dimensions, and is distributed commercially. History HYDRUS 1D HYDRUS-1D traces its roots to the early work of van Genuchten and his SUMATRA and WORM models, as well as later work by Vogel (1987) and Kool and van Genuchten (1989) and their SWMI and HYDRUS models, respectively. While Hermitian cubic finite element numerical schemes were used in SUMATRA and linear finite elements in WORM and the older HYDRUS code for solution of both the water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wageningen University And Research Centre
Wageningen University & Research (also known as WUR) is a public research university in Wageningen, Netherlands, specializing in life sciences with a focus on agriculture, technical and engineering subjects. It is a globally important center for life sciences and agricultural research. It is located in a region of the Netherlands known as the Food Valley. Wageningen University and Research is a holding comprising consists of Wageningen University and the (former) agricultural Research institutes of the Dutch Ministry of Agriculture. Wageningen University, is a research university which grants degrees at the BSc, MSc and PhD level in life and social sciences. It focuses its research on scientific, societal and technological problems in the field of life sciences and natural resources. It is widely known for its agriculture, forestry, and environmental studies programs. The university has about 12,000 students from over 100 countries. It is a member of the Euroleague for Life S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integrated Hydrologic Modelling
Integration may refer to: Biology *Multisensory integration * Path integration * Pre-integration complex, viral genetic material used to insert a viral genome into a host genome *DNA integration, by means of site-specific recombinase technology, performed by a specific class of recombinase enzymes ("integrases") Economics and law *Economic integration, trade unification between different states * Horizontal integration and vertical integration, in microeconomics and strategic management, styles of ownership and control *Regional integration, in which states cooperate through regional institutions and rules *Integration clause, a declaration that a contract is the final and complete understanding of the parties *A step in the process of money laundering * Integrated farming, a farm management system * Integration (tax), a feature of corporate and personal income tax in some countries * Territorial integration of independent or dependent territories into a state Engineering *D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constructed Wetland
A constructed wetland is an artificial wetland to treat sewage, greywater, stormwater runoff or Industrial wastewater treatment, industrial wastewater. It may also be designed for land reclamation after mining, or as a Flood mitigation, mitigation step for natural areas lost to land development. Constructed wetlands are engineered systems that use the natural functions of vegetation, soil, and organisms to provide secondary treatment to wastewater. The design of the constructed wetland has to be adjusted according to the type of wastewater to be treated. Constructed wetlands have been used in both centralized and decentralized wastewater systems. Primary treatment is recommended when there is a large amount of suspended solids or soluble organic matter (measured as biochemical oxygen demand and chemical oxygen demand). Similar to natural wetlands, constructed wetlands also act as a biofilter and/or can remove a range of pollutants (such as organic matter, Nutrient pollution, nutri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pedotransfer Functions
In soil science, pedotransfer functions (PTF) are predictive functions of certain soil properties using data from soil surveys. The term ''pedotransfer function'' was coined by Johan Bouma as ''translating data we have into what we need''. The most readily available data comes from a soil survey, such as the field morphology, soil texture, structure and pH. Pedotransfer functions add value to this basic information by translating them into estimates of other more laborious and expensively determined soil properties. These functions fill the gap between the available soil data and the properties which are more useful or required for a particular model or quality assessment. Pedotransfer functions utilize various regression analysis and data mining techniques to extract rules associating basic soil properties with more difficult to measure properties. Although not formally recognized and named until 1989, the concept of the pedotransfer function has long been applied to estimate so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Problem
An inverse problem in science is the process of calculating from a set of observations the causal factors that produced them: for example, calculating an image in X-ray computed tomography, sound source reconstruction, source reconstruction in acoustics, or calculating the density of the Earth from measurements of its gravity field. It is called an inverse problem because it starts with the effects and then calculates the causes. It is the inverse of a forward problem, which starts with the causes and then calculates the effects. Inverse problems are some of the most important mathematical problems in science and mathematics because they tell us about parameters that we cannot directly observe. They can be found in system identification, optics, radar, acoustics, communication theory, signal processing, medical imaging, computer vision, geophysics, oceanography, astronomy, remote sensing, natural language processing, machine learning, nondestructive testing, slope stability analys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Levenberg–Marquardt Algorithm
In mathematics and computing, the Levenberg–Marquardt algorithm (LMA or just LM), also known as the damped least-squares (DLS) method, is used to solve non-linear least squares problems. These minimization problems arise especially in least squares curve fitting. The LMA interpolates between the Gauss–Newton algorithm (GNA) and the method of gradient descent. The LMA is more robust than the GNA, which means that in many cases it finds a solution even if it starts very far off the final minimum. For well-behaved functions and reasonable starting parameters, the LMA tends to be slower than the GNA. LMA can also be viewed as Gauss–Newton using a trust region approach. The algorithm was first published in 1944 by Kenneth Levenberg, while working at the Frankford Army Arsenal. It was rediscovered in 1963 by Donald Marquardt, who worked as a statistician at DuPont, and independently by Girard, Wynne and Morrison. The LMA is used in many software applications for solv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hysteresis
Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of the moment often form a loop or hysteresis curve, where there are different values of one variable depending on the direction of change of another variable. This history dependence is the basis of memory in a hard disk drive and the remanence that retains a record of the Earth's magnetic field magnitude in the past. Hysteresis occurs in ferromagnetic and ferroelectricity, ferroelectric materials, as well as in the deformation (mechanics), deformation of rubber bands and shape-memory alloys and many other natural phenomena. In natural systems, it is often associated with irreversible process, irreversible thermodynamic change such as phase transitions and with internal friction; and dissipation is a common side effect. Hysteresis can be fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Retention Curve
Water retention curve is the relationship between the water content, ''θ'', and the soil water potential, ψ. The soil moisture curve is characteristic for different soil types, and is also called the soil moisture characteristic. It is used to predict soil water storage, plant water supply (field capacity) and soil aggregate stability. Due to the hysteretic effect of water filling and draining the pores, different wetting and drying curves may be distinguished. The general features of a water retention curve can be seen in the figure, in which the volume water content, ''θ'', is plotted against the matric potential, \Psi_m. At potentials close to zero, the soil is close to saturation, and water is held in the soil primarily by capillary forces. As ''θ'' decreases, binding of the water becomes stronger, and at small potentials (more negative, approaching wilting point) water is strongly bound in the smallest of pores, at contact points between grains and as films bound by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convection–diffusion Equation
The convection–diffusion equation is a parabolic partial differential equation that combines the diffusion equation, diffusion and convection (advection equation, advection) equations. It describes physical phenomena where particles, energy, or other physical quantities are transferred inside a physical system due to two processes: diffusion and convection. Depending on context, the same equation can be called the advection–diffusion equation, drift velocity, drift–diffusion equation, or (generic) scalar transport equation. Equation The general equation in conservative form is \frac = \mathbf \cdot (D \mathbf c - \mathbf c) + R where * is the variable of interest (species concentration for mass transfer, temperature for heat transfer), * is the diffusivity (also called diffusion coefficient), such as mass diffusivity for particle motion or thermal diffusivity for heat transport, * is the velocity field that the quantity is moving with. It is a function of time and space. Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richards Equation
The Richards equation represents the movement of water in Vadose zone, unsaturated soils, and is attributed to Lorenzo A. Richards who published the equation in 1931. It is a Differential equation, quasilinear partial differential equation; its analytical solution is often limited to specific initial and boundary conditions. Proof of the Existence theorem, existence and Uniqueness theorem, uniqueness of solution was given only in 1983 by Hans Wilhelm Alt, Alt and Stephan Luckhaus, Luckhaus. The equation is based on Darcy-Buckingham law representing flow in porous media under variably saturated conditions, which is stated as :\vec=-\mathbf(\theta) (\nabla h + \nabla z), where :\vec is the volumetric flux [L/T]; :\theta is the Water content, volumetric water content [~]; :h is the liquid pressure head, which is negative for unsaturated porous media [L]; :\mathbf(h) is the unsaturated hydraulic conductivity [L/T]; :\nabla z is the geodetic head gradient, which is assumed as \nabla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal friction, frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's center line than near its walls. Experiments show that some stress (physics), stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
