三维水动力学模型高精度差分格式和解法研究

采用高精度差分格式对三维水动力学问题的时均化Navier-Stokes方程进行了数值模拟，进而采用广义共轭剩余法（GCR方法）求解压力泊松方程，并采用显式三级二阶Runge-Kutts格式模拟了时间步进过程。傅立叶分析表明，文中所采用的三阶迎风紧致差分格式具有较高的精度，数值实验进一步验证了上述数值模型的准确性和有效性。     

基于语义网络的方案设计过程表达与推理

从基于机械运动方案设计的表达方法必须能支持概念设计全过程的思想出发，提出计算机辅助概念设计系统必须能够表达设计方案、产生方案、产生多个方案和确定最优方案．根据方案表达方法应具备的基本功能要求，选用语义网络技术表达设计方案过程、工艺动作、机构及其相互间的关系，通过对设计方案中机构时间配合及其影响的表达和调整实现了方案设计运动循环图表达的计算机辅助化．利用基于语义网络表示的不确定性推理技术构造待求问题的语义网络片断，通过已有设计实例与设计要求的属性值与属性值、属性值与属性值域、属性值域与属性值域三者的匹配比较构造贴近度计算公式，并对工业平缝机中的挑线机构进行了机构选型．实例证明了击模型的正确、实用性．     

基于二维提升方案的可逆双正交小波变换在渐进性无损图像压缩中的应用

分析了一维(基于行、列分解和重构)提升方案的特点，从理论上指出了一维提升方案的不足之处，提出了二维(基于子带分解和重构)提升方案，并给出了CDF(1，3)双正交小波二维提升方案的具体形式，改进的提升方案弥补了一维提升方案的不足之处，不需作‘√2’因子和归一化处理，整个小波变换是可逆的、基于整数运算的、能量守恒的，减少了误差传递的机会，用该小波变换实现了快速的、渐进性的直至无损图像压缩。     

关节软骨力学行为的数值模拟

关节软骨为一由骨胶原和蛋白聚糖固体相和孔隙流体相组成的多孔材料，其可以用基于混合物理论的两相多孔介质模型准确描述。作者采用有限元数值方法分析关节软骨图限压缩蠕变和应力松弛问题，得到软骨组织在蠕变和应力松弛过程中，固体相和流体相的速度、固体相的有效应力以及孔隙压力等随时间的变化规律。所得到的结果可以为人工软骨材料和人工关节的研制提供理论参考，对生物机械工程等领域的研究具有指导意义。     

溪洛渡拱坝二期冷却方式仿真分析研究

混凝土拱坝二期冷却一方面是为横缝的接缝灌浆创造条件，另一方面也可以达到调整坝体应力状态的目的．溪洛渡拱坝每个坝段均不设纵缝，一期冷却散热量受到限制，所以混凝土二期冷却的任务十分繁重．利用数值仿真计算方法，以溪洛渡拱坝为背景，分析了二期冷却初始温差、冷却水温、冷却时间等重要参数对高拱坝不同部位的温度及温度应力影响规律，并推荐了合理的二期冷却方式，其结论对设计单位制定温控措施及理浆方案具有参考价值．     

回旋区煤粉燃烧过程与辐射图像的关联性

高炉喷吹煤粉的喷煤枪出口到回旋区中心是煤粉燃烧的关键区域，为建立高炉回旋区煤粉燃烧与辐射图像之间的关联关系，以燃烧过程数值模拟和辐射图像信息与燃烧空间温度分布的关联性为基础，建立了二维辐射图像信息与高炉风口回旋区内三维辐射能的关系。提出将辐射图像信息作为煤粉燃烧过程数值模拟的辐射边界条件，借助燃烧过程数值模拟技术来估计燃烧介质辐射特性参数的非均匀分布，得到了高炉回旋区煤粉燃烧过程数值模拟与辐射图像处理相结合的方法，提出了一种利用二维成像技术测量三维温度场的方法。     

变形双重介质分形油藏渗流流动分析

研究了变形双重介质分形油藏渗流问题的压力不稳定响应 ,考虑了储层的双重介质特征和分形特征以及应力敏感地层中介质的变形问题 ,建立了新的应力敏感地层双重分形介质数学模型 ,包括只有裂缝发生形变和裂缝与岩石同时发生形变时定产量生产的两类数学模型。渗透率依赖于孔隙压力变化的流动方程是强非线性的 ,故采用数值方法求解了这些数学模型。探讨了分形参数、变形参数和双重介质参数变化时压力的变化规律 ,给出了典型的压力曲线图板。这些结果可用于试井分析。     

Shift visual cryptography scheme of two secret images

A new visual cryptography scheme of two secret images, which is named the shift visual cryptography of two secret images, is given. The compound function family of a general construction model is also introduced. The uniqueness and validity of this model are proved, and the minimum rows and columns for realizing the scheme are obtained. Compared with visual cryptography of one secret image, the shift visual cryptography scheme can share two secret images with the same size of pixels expansion without losing the contrast. It has randomness and various forms, and furthermore, we can also visually recover two secret images even if the two shares are different in form and color.     

A model for assessing effects of climate change on runoff in China

A model is established for assessing the effects of climate change on runoff in China based on the land surface parameterization scheme variable infiltration capacity (VIC). The entire area of China is represented by 2604 cells with a resolution of 60 km×60 km for each cell. Forcing data, soil and vegetation parameters needed by the VIC model for the entire area of China are prepared. Daily forcing data, which are obtained from 740 stations between 1980 and 1990, are interpolated to the 60 km×60 km grid system. The VIC model is run on every grid cell over the whole China, and a routing scheme is run offline with daily input of surface runoff and drainage from the VIC to get hydrograph at basin outlets. The spatial patterns of simulated runoff and mean annual precipitation are consistent very well. The results of monthly streamflow simulations over the Huaihe and Weihe River basins indicate that there is a good agreement between the observed and simulated values, and also initially indicate the rationality and feasibility of the evaluation model.     

Compact difference approximation with consistent boundary condition

For simulating multi-scale complex flow fields it should be noted that all the physical quantities we are interested in must be simulated well. With limitation of the computer resources it is preferred to use high order accurate difference schemes. Because of their high accuracy and small stencil of grid points computational fluid dynamics (CFD) workers pay more attention to compact schemes recently. For simulating the complex flow fields the treatment of boundary conditions at the far field boundary points and near far field boundary points is very important. According to authors' experience and published results some aspects of boundary condition treatment for far field boundary are presented, and the emphasis is on treatment of boundary conditions for the upwind compact schemes. The consistent treatment of boundary conditions at the near boundary points is also discussed. At the end of the paper are given some numerical examples. The computed results with presented method are satisfactory.