Parflow is an open source, object-oriented and parallel watershed scale model. It includes a fully integrated land flow with the ability to simulate complex topography, geology and heterogeneity, as well as land surface processes including land energy budget, biogeochemistry, and snow (through CLM). It can run on multiple platforms. Parflow is the result of a long, multi agency development history and is now a collaboration between CSM, LLNL, uni Bonn and UCB. Parflow is combined with mesoscale, weather code ARPS and NCAR code WRF.

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.