New Cutting Force Modeling Approach for Flat End Mill

A new mechanistic cutting force model for flat end milling using the instantaneous cutting force coefficients is proposed. An in-depth analysis shows that the total cutting forces can be separated into two terms: a nominal component independent of the runout and a perturbation component induced by the runout. The instantaneous value of the nominal component is used to calibrate the cutting force coefficients. With the help of the perturbation component and the cutting force coefficients obtained above, the cutter runout is identified. Based on simulation and experimental results, the validity of the identification approach is demonstrated. The advantage of the proposed method lies in that the calibration performed with data of one cutting test under a specific regime can be applied for a great range of cutting conditions.     

关于刚体转动的角速度和角加速度的讨论

在理论力学教学中，平面运动刚体的转动与基点无关的证明过于简单，本利用矢量代数的知识，证明平面运动刚体的角度与角加速度与基点的选择无关。     

电子束物理气相沉积Nd2O3和Yb2O3共掺杂的YSZ热障涂层研究

采用固相烧结的方法制备了10 mol% Nd2O3和Yb2O3共掺杂的YSZ(3.5 mol% Y2O3部分稳定的ZrO2)材料.掺杂材料为t/t'相,而8YSZ则为t/t'与m的混合相.测试结果表明:1 100 ℃时掺杂材料的热扩散系数为4.10×10-7 m2/s,而8YSZ(8 wt.% Y2O3部分稳定的ZrO2)的则为6.41×10-7 m2/s.在200～1 300 ℃温度范围内,掺杂材料的比热容均大大低于8YSZ.电子束物理气相沉积的掺杂材料的热障涂层陶瓷层为树枝晶结构.1 100 ℃下,掺杂材料的热障涂层热循环寿命为350～500 h,而同等条件下8YSZ涂层仅为160～200 h.     

潜射导弹级间段密封圈动态密封性能模拟试验方法

根据潜射导弹级间段密封圈在出水过程中的动态变形参数设计了一套模拟试验件和加载、加水及测量装置,采用摆锤冲击加载方式和裂纹动态张开位移测量方法再现了密封圈在导弹出水过程中的使用条件,证明密封圈在规定的开缝宽度、开缝时间和弹体内外压差的使用环境下能够保证防水和密封效果。利用两自由度冲击响应模型分析了试验的动响应曲线,给出了试验系统模态参数的识别结果。     

月球探测器转移轨道的特性分析

主要分析了月球探测器由近地点出发，在假定末端条件不变的情况下，其转移轨道的特性参数对初始条件和变轨所需的速度脉冲等的影响；考虑的特性参数的变化包括转移轨道倾角的变化，近地点高度的变化和转移时间的不同．     

预旋喷嘴径向角度对预旋特性影响的数值研究

为了降低低位进气预旋流路的气动损失，针对带有不同径向角度（0°~30°）预旋喷嘴的预旋系统进行了数值仿真，并对流动特性、温降特性和比熵增特性进行了分析。结果表明:随着预旋喷嘴径向角度的增大，预旋系统无量纲温降先增大后减小，流动阻力减小，预旋系统的流量随之增大。旋转雷诺数为2.3×107时，预旋喷嘴带径向角度的预旋系统无量纲温降比传统喷嘴最大可提高18.3%，存在某一角度使预旋温降特性达到最好。预旋系统内的耗散主要发生在预旋腔和共转盘腔内，径向角度为10°时其比熵增变化量分别占整个预旋系统总体比熵增的42.4%和30.2%；合理设计预旋喷嘴的径向角度，能改善预旋腔内气流的流动效果，并且可以减少整个预旋系统的不可逆损失。      

批评语言学中互文性理论与实践研究

选取近年来温总理记者会答台湾问题为研究对象，以辛斌提出的具体互文性和体裁互文性为分析框架，对相关对话语篇做详细的考察。在具体互文性的分析上，着重分析引用与暗指手法在温总理答台湾问题对话语篇上的具体表现；在体裁互文性分析上，分析不同体裁的融合所带来不同的交际目的和意图。     

Plastic deformation analysis and forming quality prediction of tube NC bending

Plane strain assumption and exponent hardening law are used to investigate the plastic deformation in tube bending. Some theoretical formulae including stress, curvature radius of neu-tral layer, angle of neutral layer deviation, bending moment, wall thickness variation and cross-section distortion, are developed to explain the phenomena in tube bending and their magnitudes are also determined. During unloading process, the springback angle is deduced using the virtual work principle, and springback radius is also given according to the length of the neutral layer which remains unchanged before and after springback. The theoretical formulae are validated by the experimental results or the validated simulation results in literature, which can be used to quickly predict the forming quality of tube numerical control (NC) bending.     

Avoid online radiation risk: Theoretical simulation of chromosome breaks in cells exposed to heavy ions

In this study, we report an easy and quick method on simulating chromosome breaks in cells exposed to heavy charged particles. The theoretical value of chromosome break was calculated, and validated comparison with experimental value by using premature chromosome condensation technique. A good consistency was found between theoretical and experimental value. This suggested that higher relative biological effectiveness of heavy ions was closely correlated with its physical characteristics. Also, a safe approach on predicting chromosome breaks in cells exposed to heavy ions at off-line environment can be considered. Furthermore, three key factors influencing the theoretical simulation was investigated and discussed.     

宽马赫数路德维希管风洞及其关键技术

随着高马赫数飞行器研制需求的增加，急需脉冲型风洞运行范围向中低马赫数段扩展，特别是需要具有跨马赫数运行能力。以路德维希管原理运行的管风洞试验设备，由于建设及使用成本较低、参数调节方便、流场品质高等优点，已在亚/跨/超声速及高超声速领域得到了发展和应用，体现出了宽马赫数的应用潜力。本文分析了宽马赫数脉冲型风洞发展现状，重点介绍了路德维希管风洞及其在宽马赫数应用中急需解决的关键技术，包括宽马赫数喷管设计技术、高温管外加热技术以及高温高压隔离技术。