The noise of the fan is mainly consist of circumrotatory noise and backset noise based on the theoretical analysis 首先基于风机噪声理论的分析确定了影响风机噪声源的主要因素是旋转噪声和涡流噪声。
2.
The principle of outside installation mechanism in laser tracking measurement system is introduced and a spherical mechanism method is adopted to design the 2d tracking circumrotatory mechanism according the development of laser tracking measurement system in global 作者根据国内外激光跟踪测量系统发展情况，介绍了外置式激光跟踪测距系统的原理，采用球形跟踪伺服装置的设计思想，设计了两维旋转跟踪伺服装置。
3.
In this thesis , the technology of visual fictitous design was used to design the level exchanged direction and double direction plough . first , the traction force formula of cylindrical plough face based on the prior study was deduced , and the forces of the solid model of circumrotatory pin was calculated , and visual dummy design technology was applied to analyse the force of circumrotatory pin and the parameter of pin 其次在前人研究的基础上推导出圆柱型犁体曲面的牵引阻力公式；根据该公式计算出旋转销三维实体模型所受的力，根据该力运用可视化虚拟设计技术对模型进行受力分析，对旋转销的参数进行合理设计；根据牵引阻力公式计算出安全螺栓所受的力，根据该力运用虚拟设计技术对安全机构进行设计。
