The research analysis of aerodynamic numerical simulation of grid fin

This paper presents the results of an investigation to use arc-length mesh generation and finite volume TVD scheme to calculate Euler equations for predicting the effect of geometry parameters in reducing the drag force and improving the lift-drag ratio of grid fin in the supersonic flow regime. The effects of frame and web, whose cross section shape and thickness and spacing, on the aerodynamic character of the grid fin were studied. Calculations were made at Mach 2.5 and several angles of attack. The results were validated by comparing the computed aerodynamic coefficients against wind tunnel experimental data. Good agreement was found between computed and experimental results. The computed results suggest that parameters of the grid fin's frame have the greatest effect on the grid fin aerodynamic character, especially on its drag force. It was concluded proper choice of appropriate grid fin geometry parameters could reduce the drag force and improve the lift-drag ratios.     

DNA介导的限制性发光猝灭模型及其演化计算

导出了普适性的ＤＮＡ介导的限制性发光猝灭方程：Ｉ０／Ｉ＝ａ／［１＋ｅｘｐ（ｂ－ＫＬＱＱ）］．提出了表观猝灭常数ＫＬＱ，最大猝灭量ａ和半猝灭量Ｑ１／２等概念．将高度智能化的演化计算技术引入了配合物与ＤＮＡ作用的研究中，并用ＬＱ方程对５个发光猝灭体系进行了演化优化．计算结果十分理想     

MATLAB在数值计算方法教学中的应用

结合教学实践,给出了MATLAB在计算方法教学中应用的实例,把图形演示、符号运算、工具箱等应用到计算方法课的教学中,在激发学生主动性和积极性的同时,有效地提高了课堂教学效果.     

对《用图解快速定限法确定卷积的积分限》的扩展讨论

对《用图解快速定限法确定卷积的积分限》在无限长有值函数卷积积分区间的图解分段中出现的±∞的取舍情况进行了分类和讨论,对无限长有值函数卷积的图解定限方法进行了总结,并举例说明了其使用方法.     

A numerical analysis to the non-linear fin problem

In this paper a numerical analysis is carried out to obtain the temperature distribution within a single fin. It is assumed that the heat transfer coefficient depends on the temperature. The complete highly non-linear problem is solved numerically and the variations of both, dimensionless surface temperature and dimensionless surface temperature gradient as well as heat transfer characteristics with the governing non-dimensional parameters of the problem are graphed and tabulated.     

基于函数S-粗集的Bellman原理优化算法在知识测度的应用

应用函数双向S-粗集理论实现参考模式和测试模式的动态模式匹配．用Bellman原理的动态规划算法实现全局约束定义下的Levenstein距离的计算,以此确定出参考模式和测试模式的距离测度,有明显降低计算复杂度的效果,并以无纸考试系统非标准化试题的智能评分为例进行说明。     

Numerical simulation of a direct internal reforming solid oxide fuel cell using computational fluid dynamics method

A detailed mathematical model of a direct internal reforming solid oxide fuel cell （DIR-SOFC） incorporating with simulation of chemical and physical processes in the fuel cell is presented. The model is developed based on the reforming and electrochemical reaction mechanisms, mass and energy conservation, and heat transfer. A computational fluid dynamics （CFD） method is used for solving the complicated multiple partial differential equations （PDEs） to obtain the numerical approximations. The resulting distributions of chemical species concentrations, temperature and current density in a cross-flow DIR-SOFC are given and analyzed in detail. Further, the influence between distributions of chemical species concentrations, temperature and current density during the simulation is illustrated and discussed. The heat and mass transfer, and the kinetics of reforming and electrochemical reactions have significant effects on the parameter distributions within the cell. The results show the particular characteristics of the DIR-SOFC among fuel cells, and can aid in stack design and control.     

数字电子电路调试方法

数字电路的调试，在电子技术实践中占很重要的位置，通过调试过程，使各项性能技术指标达到要求。使之正常工作，本文对数字电路的调试方法予以介绍。     

锥杆中应力波传播的放大特性

从变截面杆中一维应力平面波的无量纲控制方程组出发,采用特征线数值解法分析了应力波在锥形杆段中的传播特性,讨论了无量纲参数λ、τ_r和R对透射波放大系数和波形的影响,为应力波放大器的合理设计提供了理论依据。在Hopkinson压杆装置上对锥杆中的应力波传播进行了实验研究。理论分析计算和实验研究结果一致地表明原先由Leftheris提出的计算公式和有关结论是错误的。     

潜在语义分析:原理与应用

潜在语义分析(LSA)是关于知识归纳和知识表征的新理论，也是利用大型本语料库及统计计算方法提取和表征词汇语境意义的一种理论和方法，然而在实际应用中存在着一定的局限性，缺乏人类用来构建和应用经验知识的认知能力。建设大型语料库和提供在线语篇理解加工模式会将进一步促进LSA研究。