用解压力耦合方程的半隐式法计算流体流动

本文简介了计算传热学及流体力学中具有十分活跃而广泛实用,并自成体系的帕坦卡——斯波尔丁法。对通用微分方程在各种情况下如何确定对应的因变量、扩散系数和源项进行了说明。并应用此法计算了流体力学中具有精确解的平面poiseuiue流、纯剪切流和couette流的流场,证明此法具有很高的精度。最后以换热器强化设备中的二维通道流为例,应用“SIMPLE”法编写了FORTRAN77计算机程序,在中型计算机SIEMENS 7570 C上进行了数值计算。     

一种实用的双回线测距方法

提出了一套适用于双回线的故障选相和测距方法，该方法仅仅使用了系统单侧的电压和电流信息，并对这套方法进行了ＥＭＴＰ仿真计算，仿真结果表明，大多数情况下，本方案具有较高的测距精度，同时也证明了本方案的实用价值。     

关于De Rham定理

De Rham定理给出了关联微分拓扑和代数拓扑的有理解力的论述。本文给出了该定理的一个简捷的证明。     

样条半解析法计算变厚度板

本文将板的位移函数表示为三次样条函数与梁振型函数的乘积形式,利用位移变分原理建立控制方程,为变厚度板的计算提出一个解析半数值方法。与有限元法以及有限条法相比,计算量和内存要求得到显著节省,利用微机或袖珍机(PC—1500)即可方便地实现。数值算例表明,本文方法具有较高的计算精度。     

油田气液二相流混输的管道压降计算

本文由流体力学的基本原理出发,根据二相混合流里单位质量体积的关系,利用数学方法,推导出一个二相混合流在圆断面管道输送的压降计算的收敛迭代格式——华北油田公式Y~((n 1))=Y~((n)) (A-Y~((n))(1n(1-Y~((n))/A)-F)/1 Y~((n)-A)并根椐华北油田的实验数据,与国内外现用的十个著名公式作了对比计算,结果表明华北油田公式优于其它公式,可以作为规划设计油田时的参考。     

Operator Constructions and Volterra Mappings in Differential Games

It is proved that B. N. Pshenichnyi's -strategies and strategies based on Volterra mappings are equivalent. It is shown that Volterra mapping sought for is a boundary for some directednesses of prelimit mappings.     

Differential topological characteristics of the DSR on injection space of electrical power system

This paper analyzes the differential topological characteristics of the dynamic security region (DSR) on injection space of electrical power system by differential topology theories. It is shown that the boundary of the DSR on injection space has no suspension and is compact, and there are no holes inside the DSR defined based on controlling unstable equilibrium point (UEP) method. The 10-generator, 39-bus New England Test System, is taken as an example to show these characteristics of the DSR on injection space.     

日照作用平面二维温度场计算研究

通过“室外综合温度“方法,计算出结构正晒面的温度峰值和背晒面温度值,并由建筑物的使用性质,查出其室内温度.将这些作为二维导热微分方程的边界条件,并通过差分法和有限元法分别对该微分方程进行求解,得出各节点温度值,为后阶段温度应力分析作准备.     

p-Moment stability of functional differential equations with random impulses

By means of Liapunov's direct method coupled with Razumikhin technique some sufficient conditions for (uniform, uniform and globally asymptotic, uniformly globally asymptotic, and globally exponential) p-moment stability of the zero solution of functional differential equations with random impulses are presented, where the parameter λ(t) in (dV(t, x(t)))/dt is not required to be negative definite. Thus the obtained results are convenient to apply.     

A New Active Convex Hull Model for Image Regions

This paper presents a new active convex hull model with the following advantages: invariant with respect to the number of pixels to be enveloped; the number of time iterations is invariant, with respect to the image size; time-cheap for large image regions. The model is based on the geometric heat differential equations, derived from parabolic equation, and parameterized by arc length. To prevent the active contour from intruding into concavities and evolve it to the proper convex hull we use a vector field given as a difference between normal and tangent forces. The vector field is also used to segment an image to shells, such that a single region is present in each shell. A penalty function is developed to stop evolvement of those arc segments, whose vectors encountered boundary points of an image region. Based on the model a discrete algorithm is designed and coded by Mathematica 5.2. A condition is developed, with respect to the image size, to guarantee stable convergence of the active contour to the convex hull of the desired region. To validate the advantages and contributions a set of experiments is performed using synthetic, groundwater and medical images of different size and modalities. The paper concludes with a discussion and comparison of the active convex hull model with set of existing convex hull algorithms. Nikolay M. Sirakov received B.S. degree from School of Mathematics and Informatics-Sofia University in 1982, M.S. degree from the same University in the field of Coding Theory in 1983, and Ph.D. degree from Institute of Mechanics-Bulgarian Academy of Sciences in the field of 3D modeling and recognition in 1991. He had research and teaching positions at the Institute of Mechanics (1984–2000—Associate Professor since 1999), International Lab of Artificial Intelligence-Slovak Academy of Sciences (1990), Instituto Superior Technico–CVRM-Portugal (1993, 1998–2000), and Northern Arizona University (2001–2004). Currently Dr. Sirakov is an Assistant Professor of Mathematics and Computer Science at Texas A&M University Commerce. His research interests fall in Active Contours/Surfaces Models to image segmentation and features extraction, 3D reconstruction and visualization, 2D/3D objects matching and classification, Image Processing and Analysis, and Content Based Image Retrieval. He published over seventy papers and was a co-author of two books in the above listed fields.