长距离跑径赛项目2组弧形起跑线画法例析

根据田径规则对有些长距离跑径赛项目起跑的有关规定，讨论了这些径赛项目分2组同时起跑时，其2组弧形起跑线的渐开线画法和放射点连线画法．     

万能渐开线检查仪量值统一的几个问题

本文提出了万能渐开线检查仪量值统一的几个问题及其解决办法,指出了渐开线样板的发展前途。     

渐开线外花键挤压成形的上限解

对于渐开线外花键的挤压工艺，因齿面为渐开线型，所涉及的参数又很多，给理论分析带来一定的难度，因此目前多用试验方法寻取一些工艺参数，作者提出用上限法进行理论分析，其中包括两个扇形单元和一个渐开线单元，用该方法可取得良好的上限解，为制定工艺参数提供了一种理论分析方法。     

不分道跑起跑线的两种测画法

本文根据圆的渐开线原理和两点间的距离公式,得出两种种用放射式丈量法测画不分道跑起跑线的新画法。从而克服了原画法的某些缺点,体现了科学、准确、简使易行、丈量快和节省人力等优点。     

关于通过两个三重点曲率严格单调曲线的计算

讨论了通过两个三重点的曲率严格单调的 C~2—类曲线的计算问题;证明了用圆的渐开线拼接的可行性;给出了用四段圆的渐开线拼接曲率严格单调的 C~2—类曲线并通过给定三重点的算法。同时,还给出了一种计算通过两个三重点曲率近似单调的曲线方法。     

EFFICIENCY OF INVOLUTE GEAR DRIVES WITH UNDERCUT PINIONS USED IN WRIST WATCHES

In wrist watches gear drives with undercut pinions are used. Those pinions have got a tooth number as few as 5—7. The efficiency of such gear drives is important because of the limited energy supply. The mean efficiency of gear drives can be expressed as E_m=1/(φ_2-φ_1)(integral from φ_1 to φ_2(E(φ)dφ)) in which ~0_1, ~_2 are the approach angle and the recess angle respectively. In the discussion we assume that the friction coefficient between the two tooth flanks is constant because the sliding speed is relatively low in wrist watches and the main purpose is to find out the relation between gear parameters and its efficiency rather than to calculate the exact value of the efficiency. In normal conditions ~o_1 and ~o_2 can be found from the gear geometry without much difficulty. However when the pinion is an undercut one we have to first find the forming diameter where the involute profile starts. In this paper equations for the computation of the efficiency and the contact ratio of those gear drives are discussed.     

渐开线齿轮的润滑研究

本文从渐开线齿轮的真实运转情况出发,同时考虑齿轮齿面的滚滑速度、挤压速度、齿面的剪力影响,以及真实的啮合齿对数,分析并用数值求解了渐开线齿轮的齿面间油膜厚度和齿轮的动态特性。在小载荷的情况下,渐开线齿轮的最小油膜厚度和马丁公式计算结果相近。要减小齿轮的噪音和运动波动,必须对齿形进行合理的修形。     

基于重建图像全角度前投影的硬化校正方法

现有的硬化效应校正方法依赖于射线频谱等先验条件,校正过程较为复杂,因此提出一种基于重建图像全角度前投影的硬化校正方法.对重建后的图像进行区域分割,提取出杯状伪影主要影响的组织区域;然后进行基于像素点的全角度前投影,获得校正基算子;再将校正基算子及其高次方乘积进行线性组合获得校正算子,并将此校正算子应用于原图像从而达到校正的目的.水模、头模和西瓜的校正结果显示,本方法对单物质及近人体的物质重建图像的硬化效应均有较好的校正效果.     

MAP based blocking artifact reduction for DCT domain distributed video coding

This paper proposes a maximum a posteriori (MAP) based blocking artifact reduction algorithm for discrete cosine transform (DCT) domain distributed video coding,in which the SI and the initial reconstr...     

锥面砂轮磨齿机磨削斜齿轮时的构形原理及其误差特征

渐开线螺旋面是工程上广泛应用的廓面之一。其上存在四族特征线：渐开线、螺旋线、直母线及接触迹具有重要的工程意义。本文基于渐开线螺旋面上的特征线族,研究了锥面砂轮磨齿机磨削渐开线斜齿轮廓面的构形原理,并进行了误差特征分析。