关于有理Bézier曲面片的几何连续拼接问题

本文深入研究了有理Bézier曲面片的几何连续拼接问题,给出了GC~1拼接条件的显式表示和判断两曲面片GC~1拼接状况的判定条件。用此条件可编写一简单程序,通过输入两曲面片的控制顶点及权因子,便可以“YES”或“NO”的输出回答两曲面片的拼接是否为GC~1连续。在非GC~1拼接时,可对称地修改两曲面片使其GC~1拼接。最后,本文给出了几种CAD/CAM工程中实用的充分条件。     

一类有理曲线曲面的修改方法及计算机实现

本文首先进一步探讨三次Ｈ－样条曲线的一些性质，推导了曲线权函数性质，得到了位相似定理，证明了曲线保凸的充要条件，给出了曲线二阶几何连续的条件。然后，对三次Ｈ－样条形式的有理曲线曲面，给出了权因子的几何解释，提出了一系列修改曲线曲面形状的算法，并将其应用于各种实例，在计算机得以实现。结果表明，采用有理Ｈ－样条方法设计曲线曲面，便于局部修改，形状容易控制，能使造型达到满意效果。     

一种适合于工程应用的准C~1连续Bézier三角曲面及其构造方法

本文比较系统地讨论了Clough-Tocher三角形分割模型在Bézier三角曲面设计中的作用。并从工程应用的角度提出了一种以Clough-Tocher分割为基础,旨在原三角形区域上构造9参数Bézier三角曲面的新方法。这种新的9参数插值不仅能够消除Clough-Tother分割产生的畸变插值区域对插值曲面品质的影响,还能够有效地减轻一般9参数三次Bézier三角曲面片之间的尖端连接。本文将从工程应用的角度把这种插值曲面称为准C~1连续的9参数Bézier三角曲面。在一些实际应用中,这种准C~1连续的插值曲面对3D离散数据的拟合效果是令人满意的。     

用于高硬度模具钢SKD11的铣刀几何角度优化及试验

在切削淬硬模具钢SKD11中,为开发和选用与生产条件相匹配的具备优化几何角度的高性能铣刀,对专用于高硬度模具钢SKD11铣刀的几何角度进行了优化及试验分析.设计了4类不同几何结构的TiAlN复合涂层铣刀.从切削力、切削振动、切削变形、铣刀耐用度以及铣刀磨损机理等方面对这4类铣刀高速铣削SKD11过程进行了研究,综合评价其铣削性能,确定了在常用的高速加工生产条件下的优化铣刀.所选择的优化槽形铣刀具的寿命比之其他刀具延长3倍,在切削力和切削振动方面,该刀具具有最稳定的表现,而且大小较其他刀具下降70%.     

圆锥电磁转子系统耦合特性和控制

提出了圆锥电磁轴承的耦合动特性概念，并明确给出了其定义，在此基础上，建立了五自由度圆锥电磁轴承转子系统动力学耦合模型，进一步分析了圆锥电磁轴承耦合特性对系统最优控制器的影响。     

RBCC进气道双流道变几何方案研究

提出了一种基于双流道变几何的二元进气道设计方案:通过下流道的开关,实现进气道压缩角和收缩比的调节,使得进气道能够适应更宽的工作范围,并能兼顾与飞行器和燃烧室的一体化设计.研究表明:该方案可在保证原有双模态冲压发动机进气道高来流马赫数性能不变的前提下,将自起动马赫数降至引射/亚燃模态过渡点附近,该方案自起动马赫数为2.8;低来流马赫数时进气道具有较高的流量系数（来流马赫数为3.0时达到0.62）、较高的总压恢复系数（来流马赫数为3.0时达到0.79）和较低的阻力（低来流马赫数时降低了30%多）.      

Cylindrical and spherical dust-electron-acoustic shock waves due to dust charge fluctuation

Cylindrical and spherical dust-electron-acoustic (DEA) shock waves propagating in a dusty plasma (containing cold inertial electrons, hot Maxwellian electrons, stationary and streaming ions, and charge fluctuating stationary dust) are theoretically investigated by reductive perturbation method. It is shown that the effect of the dust charge fluctuation introduces some new features in the nonlinear propagation of the DEA waves, particularly the dust charge fluctuation provides a source of dissipation, and is responsible for the formation of the DEA shock structures. It is also found that the basic features of the DEA nonlinear structures are significantly modified by the non-planar (viz. cylindrical and spherical) geometry, and that the height of the cylindrical DEA shock structures are larger than that of the planar DEA shock structures, but smaller than that of the spherical ones. The implications of these results in laboratory dusty plasmas are briefly discussed.     

飞机武器系统易损性评价中几何描述研究

提出了飞机易损性评价中应提供的几何数据，建立了各类几何及拓扑变换的数学模型，用此模型可计算易损性评价所需的各个标准方位的几何数据。     

利用奇异酉几何构作新的带仲裁的认证码

利用有限域上奇异酉几何构作了一个新的带仲裁的认证码．并计算了这个码的参数。当编码规则按等概率分布选取时，计算出了各种攻击成功的概率。     

Interference-free wind tunnel testing of jet propelled missiles

Wind tunnel evaluation of the aerodynamic interaction effects between plume and the external flow past the missile body including the wake boundary (“slipstream”) over powered flight envelopes of rocket propelled vehicles can be greatly facilitated — or even made possible — by a methodology replacing the hot propellant by cold, inert gases. Model nozzle design is based on the second order matching of plume geometry and first order modeling of plume stiffness. Since modeled nozzles will have larger throat radii than the prototypes, one can use sting-supported, sting-fed model installations thus eliminating aerodynamic interference effects due to struts. The concepts of simulated altitude and simulated full-scale Reynolds Number greatly reduce wind tunnel occupancy time. Computer programs, covering all steps of evaluating prototype nozzle performance, model sting nozzle design, model test evaluation and interpretation have been developed. The modeling methodology is supported by experimental results obtained in an induction wind tunnel at the FFA, Bromma, Sweden and in the 16 T and VKF-A altitude tunnels at AEDC, Tullahoma, Tenn.