If the field changes slowly, we can replace the time integral by a line integral over the unperturbed orbit.
As the value in the Threshold field changes in the animation, the color of a state or territory changes based on the food stamp participation rate of that state.
We would describe this by saying 'as the Universe evolves over time and gets bigger, so this field changes in value'.
The result shows that the velocity field changes with the increase of space from shoulder and stir tool and the flow of weld metal from top to bottom and stir zone to rotation zone also weakens.
