机械零件磨损量的反求工程分析方法研究

具有复杂曲面的机械零件,磨损量测量和评价要达到定量化、精确化、可视化的目标,传统的方法已无能为力。为此提出了一种新方法,即基于反求工程技术测量和评价机械磨损量的可视化分析方法。并用研究实例,详细说明了实现过程中的关键技术,包括基于反求工程的磨损零件表面数字化测量技术、测量点云的预处理技术、磨损前后数字化模型对齐比较技术以及可视化的磨损量评价方法。

The wake of falling disks at low Reynolds numbers

We visualized the wake structure of circular disks falling vertically in quiescent water. The evolution of the wake was shown to be similar to the flow patterns behind a fixed disk. The Reynolds number, Re = Ud/v, is in the range of 40 - 200. With the ascension of Reynolds numbers, a regular bifurcation occurred at the first critical Reynolds number Reel, leading to a transition from an axisymmetric wake structure to a plane symmetric one; A Hopf bifurcation took place at the second critical Reynolds number Rec2, as the wake structure became unsteady. Plane symmetry of the wake structure was first lost as periodic vortex shedding ap- peared, but recovered at higher Reynolds number. The differ- ence between the two critical Reynolds numbers was found to be shape-dependent, as we compared our results for thin discs with those for other falling bodies, such as spheres and cones. This observation could be understood in terms of the instability mechanism of the vortical structure.

无人机在露天矿山监测中的应用

在露天矿山开采过程中,对矿山进行实时动态监测很有必要,它不仅能够实时掌握开采进度和开采方案实施的准确性,还有利于数字矿山建设。本文以河北省保定市涞源县某露天矿区为例,利用Pix4Dmapper软件对无人机航拍影像进行数据采集与处理,获取矿区的三维点云数据、数字正射影像和数字地表模型,并利用Arc GIS和Global Mapper软件对生产成果进行矿山开发占地分析,实现露天矿山三维可视化。本文为准确掌握矿山环境治理执行情况,把握矿山开发整体情况给予了有力的参考和借鉴作用。