The U.S. patent office refuses to assess claims for perpetual motion devices unless the inventors can produce working models.
美国专利局拒绝评估认证永动装置，除非设计者们能制造出可用的模型。
After 1870, inventors were no longer obligated to include models with applications. Today, models are required only for perpetual motion machines.
1870年之后，发明家们在申请专利的时候已经不必要再附上模型了。如今，只有永动机在申请专利时才需要模型。
Laboratory physical model tests were performed to study the performances of the motion characteristics and the mooring forces of pontoon floating breakwater models.
实验结果表明浮箱的相对板宽和锚链刚度是影响模型运动和锚链力的重要因素。
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