Polygonal extrusion

A sweeping operation called polygonal extrusion is defined to improve the modeling power of CSG-based modeling. It is assumed that a 2D cross-sectional polygon (sweeping polygon) moves in space while its containing plane is kept orthogonal to the tangent direction of the trajectory curve, a planar polygonal chain having no self-intersections. The objective of the paper is to compute the boundary of the swept volume of the sweeping polygon as a set of polygons (or triangles). The most significant challenge to accomplishing this objective is the problem of trimming the swept volume. To solve the trimming problem, 2D-curve offsetting methods are employed. Two algorithms are presented for polygonal extrusion that are based on different offsetting methods, the Voronoi diagram and PWID offset. The proposed algorithms have been implemented and tested with various examples. Published online: 28 January 2003     

纤维体积分数对K3D/MCPA复合材料力学性能的影响

本文研究了纤维体积分数对三维编织芳纶纤维增强铸性尼龙(简称K3D／MCPA)复合材料力学性能的影响。研究表明，K3D／MCPA复合材料有优异的抗冲击性能，冲击强度比三维编织芳纶纤维增强铸性尼龙(简称C3D／MCPA)和纯基体均有大幅度的提高，且随着纤维体积的提高而升高。K3D／MCPA复合材料剪切强度随纤维体积比的增大而增大，其纵向剪切强度低于纯基体和C3D／MCPA复合材料，但其横向剪切强度高于它们。K3D／MCPA复合材料弯曲强度与弯曲模量随纤维体积比的提高而提高，但与相同体积比的C3D／MCPA相比，K3D／MCPA的弯曲强度与弯曲模量均较低。     

Rendering of Surface and Volume Details in Volume Data*

Aiming at the detail rendering in volume data, a new volume illumination model, called Composed Scattering Model (CSM), is presented. In order to enhance different details in volume data, scattering intensity is decomposed into volume scattering intensity and surface scattering intensity with different weight functions. According to the Gauss probability distribution of gray and gradient of data, we propose an accurate method to detect the materials in a voxel, called composed segmentation. In addition, we discuss the principle of constructing these weight functions based on the operators defined in composed segmentation. CSM can generate images containing more details than most popular volume rendering models. This model has been applied to the direct volume rendering of 3D data sets obtained by CT and MRI. The resultant images show not only rich details but also clear boundary surfaces. CSM is demonstrated as an accurate volume rendering model suited for detail enhancement in volume data sets.     

HDPE/CB-GP复合材料体系电性质的研究

当HDPE含量46％（质量分数，以下同）、其它添加剂（如抗氧剂、阻燃剂、交联剂和润滑剂等辅助填料）的含量11％，两种导电填料石墨（GP）和碳黑（CB）的总含量为43％时，研究结果表明石墨含量的变化对HDPE/CB-GP复合材料室温电阻率、阴C强度和后NTC强度有显著的影响．HDPE/CB-GP复合材料中GP的含量〈8．6％时，样品的室温电阻率〈30Ω·m，PTC强度〉7、后NTC强度〈1．3；电阻率．温度曲线经过17次冷热循环后重现性好，复合材料具有实际应用价值；GP在复合材料中为层片状结构。     

模拟退火算法用于蒸汽吞吐井生产能力的预测

模拟退火算法是一种利用统计力学观点求解优化问题全局最优解的方法,是目前解决优化问题的一种比较先进的方法。本文应用模拟退火算法对蒸汽吞吐注采参数进行优化设计,并确定出了6个吞吐周期的最优周期产油量和周期注蒸汽量,较实际周期产油量和实际周期注汽量均有明显增加。将各周期的优化累积产油量和优化累积注汽量画在累积产油量与累积注汽量的双对数坐标中,得出累积注汽量和累积采油量关系曲线(简称注采关系曲线)。将该注采关系曲线外推估算了该井未来周期的累积产油量和累积注汽量,从而达到对蒸汽吞吐井生产能力的预测。     

变风量空调系统

介绍了变风量空调系统（VAV系统）的特点、末端装置的型式以及最小送风量的确定方法，指出了VAV系统的研究重点和发展前景。     

CAD8903机芯的视频音频转换电路设计

本文概要介绍了CAD 8903机芯采用国产集成电路CD7680,CD74211,DG4053实现音频、视频切换功能的电路,并对CD7680中音频信号处理电路的特殊用法进行了说明。     

电解法烟道气二氧化硫在线监测系统的设计

介绍了一种烟道气中SO2在线检测系统，该系统可以实现24h不间断地监测烟道气中SO2的体积分数和质量浓度，同时将信息经网络传送给环保有关部门，具有一定的新颖性、可靠性、准确性。     

Resilient metal spring network silicone-matrix composite for separable interconnections

Resilient metal spring silicone-matrix conducting composites for separable interconnections in electronics were fabricated by the impregnation of silicone into a preform comprising randomly oriented C-shaped Cu-Be springs and a small proportion of Sn-Pb solder, which served to connect the springs at some of their intersections. Composites containing 6.1-9.8 vol.% total filler exhibited volume electrical resistivity 0.5-1.0 mΩ.cm and contact resistivity (with copper) 11-17 mΩ.cm². A compressive stress of about 30 kPa was needed for the low contact resistivity to be reached. The volume 17-26% and the contact resistivity increased by 5% after heating in air at 130-150°C for seven days. Composites containing <9 vol.% total filler showed no stress relaxation for seven days at 6.0% strain.