Numerical instabilities are often encountered in FE solution of continuum topology optimization. The essence of the numerical instabilities is given from the inverse partial differential equation (PDE) point of view. On the basis of the strict mathematical theory, a novel method, named as window filter and multi-grid method, which solves the numerical instabilities, is proposed. Convergent analyses and a numerical example are presented.

针对导弹天线罩这类薄壁复杂回转体测量的难题．提出了一种新的测量原理，研制了专门的天线罩几何参数测量仪，设计了测量的软、硬件系统。介绍了测量仪的工作原理、测量系统的构成以及误差评定和数据处理的方法，并给出了测量实践结果。测量仪使用结果表明，实现了对工件准确、快速、经济的目动测量，以及对测量结果的评定和可视化处理，取得了满意的效果。

The radome is a revolution shell part made of hard and brittle material and has 3-D complex curved surface. The electric thickness of the radome is an important electromagnetic performance index, determined by the geometric thickness and the dielectric constant of the material. For the semi-finished radome, its electric thickness can usually not meet the requirement of the design owing to the error of the geometric thickness and the non-uniformity of the dielectric constant of the material. Therefore, it is necessary to precisely grind the inner surface of the radome to compensate the electric thickness error by altering the geometric thickness. To this end, a three-axis CNC precision measuring and grinding machine tool, which is controlled by a industrial personal computer (IPC) and a programmable multi-Axis controller (PMAC), was designed and developed. In order to avoid installation errors caused by separate loading operation and to ensure the grinding accuracy, the measuring and grinding process of the radome are accomplished in the same installing position on the machine tool in a manner of "once-loading and two-step-operation". First, the inner surface is precisely measured to set up a process datum and then, the finish grinding process is performed based on the datum and the required grinding allowance in the machine tool. It is shown in practice that the radome ground by the machine tool satisfies the requirement for the precision of the electric thickness.

An analysis of the cutting performance of multipass abrasive waterjet (AWJ) machining is presented based on an experimental investigation on an 87% alumina ceramic. It is shown that with a good combination of cutting parameters such as nozzle traverse speed, multipass cutting demonstrates distinct superiority over the single pass cutting. Plausible trends of kerf quality and depth of cut with respect to the number of passes, nozzle traverse speed and nozzle traverse direction are analyzed. A general guide for the selection of cutting parameters in multipass cutting is finally presented based on the analysis.

基于物体表面图像灰度信息的三维几何形状反求（由明暗恢复形状），已成为工业界和学术界研究的热点问题之一。首先给出描述该问题的数学物理模型，并利用变分原理将其转化为一个泛函的极小化问题，然后应用有限差分思想和非线性最小二乘方法，将该泛函极小化问题归结为求解线性方程组。最后利用该算法产生的迭代公式对合成图像进行计算，并应用曲面造型软件CAXA（制造工程师）进行曲面重构，从而验证了该方法的有效性和可行性。