Gravity model is a good tool to explain the direction and flow of bilateral trade, and has gained success on the empirical research in international trade.
引力模型作为解释双边贸易流向和流量问题的有力的分析工具，已经在国际贸易实证研究中获得了相当的成功。
2
Objective To establish the method to assess mathematically the compensation of flow in bilateral vertebralartery(BVA).
目的建立定量描述双侧椎动脉血流代偿性的方法。
3
The research via gravity model shows that the system quality of each country will impact bilateral trade effectively, and the trade flow is large between the countries with similar systems.