用七次幂多项式拟合片体线型和主体横剖面面积曲线，以线性兴波阻力理论为基础计算兴波阻力；

By approximating the lines of the demi-hull and the main body's section with 7-order polynomial, the authors calculate the wave-making resistance of a SWATH based on the linear theory.

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文章采用单位功率因数pwm整流器和斩波电路组成开关电源主体，建立以pwm整流电路为输入电路的新型开关电源。

In this paper, using unity power factor PWM rectifier and chopper circuit, it establishes a new type of switching power supply about PWM input rectifier circuit.

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