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Abstract.With the rapid development of information technology, and network information technology, modern information technology can make the arduous work fast and easily. A complete online examination system can enable students to check the learning results and find their own disadvantages. Therefore, the online examination system can improve the learning efficiency.

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Abstract. This paper mainly introduces the various methods and techniques of using 3D solid design drawings of Inventor jewelry products. The main contents include: jewelry design and drawing of the preparation of knowledge, Inventor basic knowledge, jewelry design Inventor function commands, fast drawing entity tool, jewelry design in the drawing.

This paper introduces the research background of the two-dimensional circular part layout problem, analyzes the complexity of the layout problem, studies the current research status of the circular part layout problem, and finally, lists the relationship between layout methods and layout schemes of the two-dimensional circular part layout problem.

In order to solve the sealing problem of the cooling and evaporating medium of the large air volume fan in the large ship equipment, a five-stage, nine-tooth, large-gap magnetic fluid and magnetic grease combined rotary sealing device is designed, which is suitable for the environment with high rolling and high corrosion of large ships. Through the theoretical derivation of the pressure resistance formula and the Ansys finite element analysis, it is found that the pressure resistance of the seal increases with the increase of the saturation magnetization of the magnetic fluid, the yield stress of the magnetic grease and the magnetic field gradient in the seal gap. On the sealing test bench, the sealing pressure test was carried out on the device. When the maximum clearance is 0.7 mm, the single-stage pressure resistance capacity can still reach 20 KPa, and the sealing capacity remains stable with the increase of rotating speed. Theoretical and experimental results show that the design is suitable for large clearance sealing of high-power motors or other high vibration equipment in corrosive environment.

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