DM4型超声波测厚仪在高温测厚过程中的应用

简要阐述了DM4型超声波测厚仪的使用方法、注意事项及在高温测厚过程中应注意的一些问题，同时对高温测厚的一些经验公式进行了初步探讨。     

染料云的形态结构表征—染料的径向分布与投影密度分布

彩色影像的最小像元—染料云的形态结构的表征有两种方法：一种是染料云的染料浓度的径向分布；另一种是染料云的投影密度分布．前者一般是从染料云形成过程的模拟计算得到；后者是从微密度计对染料云的扫描测得．本文提出了将染料的径向分布转换成相对投影密度的一种近似计算方法，从而使两种形式的表征方法相互联系起来，这为进一步优化染料云形态的研究打下基础．     

Spacing of edge fractures in layered materials

Opening-mode fractures developed from a free surface in a layered material often terminate at the interface that divides the fractured layer and the underlying layer. They also display regular spacing that is of the same order of magnitude as the thickness of the fractured layer. We have investigated the stress distribution between two adjacent edge fractures as a function of the ratio of fracture spacing to thickness of the fractured layer using a two-layer elastic model with a fractured top layer. The results show that when the ratio of fracture spacing to the layer thickness changes from greater than to less than a critical value the normal stress acting perpendicular to the fractures near the free surface changes from tensile to compressive. This stress state transition precludes further infilling of fractures unless they are driven by mechanisms other than a pure extension, or there are flaws that significantly perturb the local stress field between the fractures. Hence, the critical fracture spacing to layer thickness ratio defines a lower limit for fractures driven by extension, which also defines the condition of fracture saturation. The critical value of the fracture spacing to layer thickness ratio is independent of the average strain of the fractured layer, and it increases with increasing ratio of Young's modulus of the fractured layer to that of the underlying layer. The critical value increases with increasing Poisson's ratio of the fractured layer, but it decreases with increasing Poisson's ratio of the underlying layer. For the case with the same elastic constants for the fractured layer and the underlying layer, the critical spacing to layer thickness ratio is about 3.1. Delamination between the fractured layer and the underlying layer makes the critical spacing to layer thickness ratio much greater. Infilling fractures grow more easily from flaws located near the bottom of the fractured layer than from those located near the free surface when the spacing to layer thickness ratio is less than the critical value. The propagation of an edge flaw between adjacent edge fractures is unstable, but for the flaw to propagate to the interface, its height has to be greater than a critical size, that decreases with increasing fracture spacing to layer thickness ratio. The propagation behavior of an internal flaw with its lower tip at the interface depends on the edge fracture spacing to layer thickness ratio. The propagation is unstable, when the fracture spacing to layer thickness ratio is greater than a critical value; stable, when the fracture spacing to layer thickness ratio is less than another critical value; and first unstable, then stable, and/or unstable again, when the fracture spacing to layer thickness ratio is between these two critical values.     

薄膜厚度的多探头计算机实时测控系统

阐述了用声阻抗法实时监测薄膜沉积的原理，介绍了一种使用个人计算机的实时测控系统。它可在真空镀膜的过程中对膜厚进行实时测量和控制，允许使用多个石英晶体探头，以适应多源共蒸发真空镀膜的需要。监测的过程和结果可以存储下来进行分析。为优化镀膜工艺提供了很大的方便。     

UG NX二次开发在CAD模型离散中的应用

在CAD模型已知的零件数字化检测中,为将CAD模型和零件的实测点云模型进行对比分析,首先要解决CAD模型离散为点云数据的问题。针对这一问题,提出了一种基于UG NX平台二次开发获得点云数据的方法。介绍了UG NX二次开发的工具及其基本特点,并综合运用二次开发工具和Visual StudiO2010开发环境在UG NX10.0中设计了完成CAD模型离散的对话框。阐述了CAD模型离散的原理、基本流程,编写对话框中的回调函数实现了离散功能,获得了点云数据。将离散结果与原模型进行对比分析,表明离散结果可以很好地代表CAD模型。     

特种高强度钢等厚冷压成球面工艺

球缺封头传统成形工艺无法满足某水下使用设备球形板形状、厚度、力学性能、重量等设计要求。通过开展特种高强度钢等厚冷压球面工艺研究，掌握了冷压成形中板厚变化规律、形状误差控制、消除冷作硬化及保证力学性能控制和成形压力控制四项主要关键技术，实现了特种高强度钢等厚球面冷压成形，满足了球形板设计要求。     

HNS的临界厚度测试研究

为了验证六硝基茋(HNS)的爆轰波传播性能,采用楔形装药方法对三种HNS装药的临界厚度进行了实验研究,其装药密度分别为1.00,1.570 g·cm-3,粒径分别为20 μm,9 μm,89 nm.结果表明: HNS粒度对爆轰波传播特性影响显著,粒度减小,临界截面厚度变小,即爆轰波传播性能增强;装药密度的增加利于爆轰波传递,在装药密度为1.570 g·cm-3时,HNS-Ⅳ的临界厚度只有0.46 mm.     

Application of Paris’s law to thermal cycling-induced failure in semiconductor device patterns

The present work provides a semi-empirical model to show that the growth rate of thermal displacement-induced cracks in semiconductor devices depends on pattern thickness. Paris’s law is adopted to characterize the growth rate of cracks during thermal-cycling. The crack propagation rate is estimated from the semi-empirical relation (dc/dN)_v=C(ΔK)ⁿ, where ΔK indicates the range of an applied stress intensity factor, and C is a scaling constant. The applied stress intensity factor is related to the initial crack length as ΔK=YΔσ(πc)^1/2, where σ represents the thermal displacement-induced normal stress, c describes the pre-existing crack length, and Y is a geometrical factor. The resulting crack growth rate can be expressed as a function of device pattern thickness: dc/dN∞(1/t)^m, where t describes the pattern thickness, and m is another constant. The present semi-empirical results showing the relationship between the crack growth rate and pattern thickness indicate that if a semiconductor device pattern becomes thinner by 68%, its susceptibility to thermal cycling-induced damage will be enhanced by 76%.     

一种城区LiDAR点云数据的抽稀算法

当城区LiDAR点云数据密度较大时，存在大量的数据冗余，造成了计算量大、效率低、显示不便等一系列问题，使得建筑物的三维可视化及三维重建等应用受到较大挑战。针对该问题，结合泊松碟采样在测地空间中的地形自适应特点，提出了适用于城区LiDAR点云数据的抽稀算法。泊松碟采样随机将与已有采样点的测地距离大于某一阈值的点加入采样点集，并不断重复这一过程直至没有新的采样点加入为止。在此基础上，依据LiDAR点云数据的特点，定义了一种新的与所选点与其邻域内其他点间高度差标准差相关的加权测地距离，改进了泊松碟采样算法。该方法能有效调整城区建筑物的采样率，从而尽可能地保持建筑物的原始特征，并保留良好的可视化效果。四组对比实验结果表明了该算法的适用性及高效性。     

重离子核反应中的中子辐射屏蔽计算

在分析重离子核反应中中子的产生和有关保健物理数据的基础上,确定了用于屏蔽计算的核反应系统和计算参数,计算了单核能为100MeV、束流强度为3.9×10~(11)离子/s的~(12)C离子轰击Cu靶时距靶5m和10m处达到不同中子剂量当量率时需要设置的混凝土(ρ=2.3g/cm~3)屏蔽厚度。