影响带式输送机托辊使用寿命的因素

在带式输送机的设计中,托辊的使用性能和合理布置对于带式输送机的正常使用、稳定运行有着不可忽视的重要作用。过去,受到机械加工工艺水平及设备精度低的限制,托辊的加工精度成为影响托辊使用寿命的主要因素。通过多年皮带机设计经验与生产经验的积累以及用户反馈发现,托辊轴承的使用寿命才是其使用性能及其使用寿命的关键因素。     

Multi-optimisation of the screw kick in rugby by using a genetic algorithm

This paper describes the use of Pareto-optimal solutions for the screw kick in rugby. We attempted to optimise the initial conditions for a screw kick. The optimisation was carried out using an elitist non-dominated sorting genetic algorithm. Distance achieved in flight is considered as an objective function, as well as the lateral deviation between the ball and the touchline, or the flight time. Six initial conditions were defined as control parameters: the magnitude of the velocity vector, the flight path angle, the azimuth angle, the spin rate, the pitch angle and the yaw angle. The results are summarised as follows: it is impossible for both objective functions to be satisfied simultaneously, although the greatest distance achieved in flight and the smallest value of the lateral deviation between the ball and the touchline, or the least flight time, is the ideal situation. This kind of conflicting solution is called a ‘Pareto-optimal solution’. The optimal kick in Pareto-optimal solutions made by the leg nearest the touchline produces a greater flight distance than the optimal kick in Pareto-optimal solutions made using the leg furthest from the touchline. The initial pitch angle, which is the angle between the longitudinal axis of the ball and the horizontal plane, should be comparable to or slightly greater than the initial flight path angle in order to satisfy the Pareto-optimal solutions.     

汽车上的螺纹连接

一部汽车有上千件、甚至多达几千件螺纹连接,要正确地使用和维修汽车,必须熟悉各种螺纹连接件的结构、作用和使用注意事项。     

螺栓的疲劳分析

阐述螺栓由于受轴向变载作用产生交变应力而引起的疲劳破坏;分析螺栓的受力、疲劳破坏的主要影响因素、螺栓设计疲劳曲线及提高螺栓疲劳强度的措施.     

多组分混合物在"犁刺"管上强化传热研究

研究多组分混合物在水平光滑管、螺纹管与“犁刺”管上的冷凝强化传热。找出了比新型的螺纹强化传热管性能更好，具有开发价值的“犁刺”强化传热管（“犁刺”管的传热效果约为光滑管的14～15倍，螺纹管的传热效果约为光滑管的10倍以上)。     

电软起动技术在带式输送机中的应用

介绍了矿井带式输送机控制技术的发展方向，在空间离散化条件下把皮带作为一个弹性体进行了受力分析，指出直接起动和停止的危害，提出如何降低带式输送机的启动系数，叙述了国内外带式输送机常用的软起动方式及优缺点，对电软起动技术的工作原理、优点和在矿井带式输送机控制中的应用以及电软起动的四种方式进行了阐述。     

数字图像分析方法在螺纹检测中的应用

This paper describes the use of computer-aided measurement for external metric screw threads.Thread parameters,including thread pitch,thread angle,pitch giameter and major diameter,were measured with CCD cameras and image analysis software.New technologies such as digital image processing were used to increase the efficiency of measurements.In this study,by reconstructing the toolmaker‘s microscope,the computer-aided semi-automated measuring system was developed,which could evaluate the accuracy of screw thread fpofile.It is concluded that the measuement accuracy is comparable to that of traditional toolmaker‘s microscope method.     

基于时间序列法的胶带机火灾信号分析与合成

胶带机火灾信号属于非平稳的随机过程,根据实际遇到的随机信号可以由一个白噪声信号通过一个有理传输函数系统逼近的原理,利用自回归模型分析、合成出了胶带机火灾和非火灾信号。将格式滤波器结构引入了单通道自回归模型的参数求解中,避免了应用横向滤波器时对数据窗两侧信号做人为假定为零的假设,降低了数据窗口较短时产生的误差。结果表明,通过该方法合成出的胶带机火灾和非火灾信号可有效扩充测试火灾探测算法的数据集、验证算法的准确性和灵敏度。     

多刚体系统动力学分析方法(Ⅱ)

本文在文[1]的基础上，分析和综述了Kane方法、旋量方法以及变分方法在多刚体系统动力学分析中的应用，并导出相应形式的系统动力学方程．     

多环反馈电流模式二阶滤波器

本文提出了用改进式电流传送器实现多环反馈电流模式二阶低通、高通、带通、陷波滤波器．给出了PSPICE仿真结果，进一步证实了理论分析的正确性、电路的品质因素Q和截止频率ωp、增益H0独立可调，该电路的无源灵敏度低，适于全集成实现．