Cxtfit is a computer software developed by the saline soil laboratory of the United States to study one-dimensional soil solute transport. Based on Levenberg Marquardt algorithm, cxtfit uses the function optimization method of nonlinear least square to fit the breakthrough curve of solute mixture replacement experiment, solves the model parameters, and predicts the concentration distribution of solute in soil with time and space. Cxtfit is based on the solute convection dispersion equation. The original cxtfit1.0 was developed and compiled by Parker and van Genuchten, and gradually improved into today's cxtfit2.0, which contains more equation analysis for different initial boundary value problems and generation problems. The software includes three different types of solute transport models: equilibrium CDE model, physicochemical nonequilibrium CDE model and stochastic flow tube model.

IBIS model is used to describe the input, output and I / obuffer behavior characteristics of IC devices, and to simulate the interaction between buffer and on-board circuit system. The core content of IBIS model is the buffer model, because these buffers produce some simulated waveforms, so the simulator uses these waveforms to simulate the influence of transmission line and some high-speed phenomena. Specifically, Ibis describes the input and output impedances (in the form of I / V curves), rise and fall times, as well as pull-up and pull-down in different situations. Engineers can use this model to analyze Si, crosstalk, EMC and timing in the circuit system on PCB.

Calite model is an interactive screening model planned and managed by the state water project (SWP) and the Central Valley Project (CVP) in California. It simulates the hydrology of the Central Valley, reservoir operation and delivery allocation decisions to SWP and CVP, delta salinity response to changes in river flow and outlet, and resident ecosystem index. The power of filtering models like callite is the ability to quickly simulate system operations and merge changes relatively easily. The current version of calite simulates the operation of the system on a monthly basis. On the latest modeling computer, it takes about 6 minutes (compared with 30 minutes of calsim), recording a full 82 years of records (water year 1922-2003). Scenarios can be run using a variety of different user specified parameters related to hydrometeorology, requirements, facilities and infrastructure, regulations, and system operations. Through the integrated post-processing tools of the model, we can observe, compare and analyze the results.

One dimensional River Stuart model

The vegetation model SSiB was developed in the late 1980s. It is based on the SIB proposed by sellers et al. In 1986. The simplification is mainly aimed at the calculation of radiation transfer, aerodynamic drag coefficient and stomatal resistance coefficient in plants. The simplified SSiB has 1 layer of vegetation, 3 layers of soil and 8 forecast variables (moisture of 3 layers of soil, water content of vegetation surface, snow cover of soil surface and leaf surface temperature). Therefore, there are only two predictors: soil surface temperature and deep soil temperature. In the model, stomatal resistance coefficient, soil resistance coefficient, vegetation boundary layer resistance coefficient and two-layer aerodynamic resistance coefficient are used to control the dynamic, thermal and water exchange between the earth and the atmosphere.

DRAINMOD is a computer simulation model, which simulates the hydrological conditions of poorly drained high water level soil hourly with a long climate record (for example, 50 years). The model predicts the impacts of drainage and related water management practices on groundwater table, soil moisture status and crop yield. The parallel method is mainly used to analyze the hydrological conditions of some types of wetlands to determine whether the wetland hydrological standards meet the requirements of drainage or part of the drainage site. The model is also used to determine the hydropower capacity of the sewage treatment system. The model has been successfully tested and applied to various geographical and soil conditions. Over the past 20 years, the model's capacity has been extended to predict the impact of drainage and water resource management practices on hydrology and water quality in farmland and watershed wide agriculture and woodland.