Abstract : in this paper the mathematical model for shape optimization of arch dam subject to crack - depth constraint is estabilshed and the super finite element method ( sfem ) for arch dam cracking analysis is used as the re - analysis method . the research findings on xiaowen arch dam show that the shape optimization of arch dam subject to crack - depth constraint may further help reduce the volume of dam 文摘:本文引进裂缝深度约束条件，研究了拱坝开裂条件下的体形优化设计问题.结构分析采用超级有限单元法，既能有效控制计算规模又能方便地反映结构开裂的局部特性.对小湾拱坝和溪洛渡拱坝进行的优化设计研究表明，在优化过程中允许开裂并考虑开裂约束条件，可以更好地挖掘拱坝潜力，进一步减小坝体混凝土方量
In the third part , the essences of steganography and disadvanges of common visual perception evaluation , such as psnr and wpsnr are studied . based on analysis local error that is introduced by embedding information , combining hvs , three objective perception evaluation method for steganography performance are proposed , which are based on human visual systems and local statistic error distribution respectively . in the steganalysis part , a steganography security statistic attack model and methods for some steganography methods are presented 在信息隐藏的性能评价方面，研究了常用的峰值信噪比，加权峰值信噪比等前人提出的感知性能评价准则，指出针对信息隐藏的性能评价不能单纯从视觉特性出发，提出从信息隐藏的数据特性和感知特性出发，结合局部特性来考察失真误差的变化的思想，并据此提出基于局部区域误差统计分布和视觉掩模方法评价信息隐藏性能的方法。
Complex systems are the ones with a great many interactive components among which the relationships are complicated and uncertain . the global - behavior of complex systems is non - linear and cannot be deduced from the local characteristics . the fmacial stock market in econimic system , which involves lots of investors , corporations , governments and so on , is such a system 所谓复杂系统，指的是系统具有大量交互成分，其内部关联复杂、不确定，总体行为具有非线性，即不能通过系统的局部特性，形式地或者抽象地描述整个系统特性的系统。
Thirdly , based on the geometrical differential constraints and force balancing constraints of the coordinated flexible manipulators , the mutual relationships between the kinematic and dynamic parameters in static configuration have been presented . the manipulation stiffness of the coordinated system has also been proposed . the manipulability of the flexible robot system has been then analyzed in two aspects : i ) the global characteristics in the manipulation workspace based on the manipulation stiffness ; ii ) the local property of the reachable boundary of generalized forces 然后，利用柔性机器人协调抓取的几何微分约束和力平衡约束，通过深入分析系统在静态位形时其内部各运动参量和力参量之间的关系，定义了系统的操作刚度，从两个方面对系统的操作性能进行了分析： 1 ）操作空间中，基os于系统操作刚度的全局特性； 2 ）在一定约束的条件下，系统操作力矢端可达二边界的局部特性。
In the terms of interpolation , the image reconstructed from nearest interpolation or linear interpolation has good edge but serious noise ; reconstruction from 4 * 4cubic interpolation or three b - spline or three - order lagrange interpolations has better local character . 2 x 2cubic interpolations which has both better edge and local character is the ideal interpolation , the following is the basic principle during reconstruction : ( 1 ) the more width of interpolation , the more number of summation and the more order of interpolation polynomial , the higher of density resolution ; ( 2 ) the more of interpolation polynomial and width of interpolation , the more of reconstruction time simultaneously , aimed at eliminating the effects of noise contained in projection data , in this paper , author analysis cause and effects of common artifacts . importantly , discusses convolution back - projection reconstruction algorithm with a shift axis of rotation has been derived for correcting images that acquired with a divergence axis of rotation using the fan beam geometry with an angle - equaled detector 在ct图像重建时，选择有限带宽窗有较好的空间分辨率，三角形窗有较好的密度分辨率，选择余弦窗则使得空间分辨率与密度分辨率的折衷；从窗函数的频谱角度来讲，可以用于图像重建的一个良好的卷积窗函数应该具备以下条件： ( ? )小的3db带宽b ，即最小的主瓣宽度； ( ? )最小的旁瓣最大峰值a ； ( ? )最大的旁瓣峰值衰减速度d ；就内插函数而言，临近点内插与线性内插重建图像噪声大，但有较好的边缘与细节； 4 4三次内插、三次b -样条与四次拉格朗日多项式内插图像平滑，局部特性较好。
The formulation for the error analysis of acoustic radiation problem calculated by the boundary point method ( bpm ) is put forward ; the physical explanation of the boundary point analysis of the acoustic radiation problem is given ; the influence of the particular solution on the calculation stability of the bpm is studied ; the etthanced volume source boundary point method ( evsbpm ) is presented ; a test for the effectiveness of the evsbpm is carried out on the aspects of its calculation precision , calculation speed , calculation stability , adaptation to the geometric shape of vibrating body as well as its ability to overcome the non - uniqueness problem through various examples with different boundary shapes and different boundary value distributions 第三章导出了边界点方法分析振动声辐射问题的误差估计理论公式，揭示了边界点方法分析振动声辐射问题的物理本质；研究了特解场的局部特性对边界点方法的数值稳定性的影响；改进了现有的特解场构造方法，提出了改进体积源边界点方法；通过诸多不同边界曲面和不同边界量分布的声辐射算例，从计算精度、计算速度、计算稳定性、对振动体表面几何形状的适应性以及克服解的非唯一性等方面，对改进体积源边界点方法的有效性进行了考证。
