The gravity model explicitly relates flows between zones to interzonal impedance to travel.
重力模型明确的通过地区间的阻抗来将分布量和小区联系起来。
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Gravity model
Gravity models are used in various social sciences to predict and describe certain behaviors that mimic gravitational interaction as described in Isaac Newton's law of gravity. Generally, the social science models contain some elements of mass and distance, which lends them to the metaphor of physical gravity.