A weighted penalty finite element method for the analysis of power-law fluid flow problems

In this paper, a new finite element method for the flow analysis of the viscous incompressible power-law fluid is proposed by the use of penalty-hybrid/mixed finite element formulation and by the introduction of an alternative perturbation, which is weighted by viscosity, of the continuity equation. A numerical example is presented to exhibit the efficiency of the method.The Project Supported by the National Natural Science Foundation of China.     

一种用于幂律流体流动分析的加权罚有限元法*

本文采用罚-杂交/混合有限元列式,并引用由粘度加权的连续方程的另一种摄动,建议了一种新的粘性不可压幂律流体流动分析的有限元法.提出了一个数值算例,以显示方法的有效性.     

Stokes流动的罚-杂交有限元分析*

本文建议了一种用于分析Stokes流动的罚-杂交变分原理,其中,偏应力张量和静水压力事先满足线动量平衡.建立了相应的有限元模型.由此,压力可在列式过程中消去,使得有限元矩阵方程仅以节点速度作为唯一的求解未知量.推导了几种4-节点和8-节点四边形单元.通过数值算例,显示了单元性能.     

关于捷联惯性系统全姿态计算

—对于全姿态工作的捷联惯性系统，提出了物理奇点和计算奇点两种不同的概念，探讨了全姿态工作的含义，给出了新的姿态角计算框图。     

A penalty-hybrid finite element analysis of stokes flow

A type of penalty-hybrid variational principle is suggested for the analysis of Stokesian flow. On such a basis, a finite element model is formulated featuring, among others, a priori satisfaction of the deviatoric stress and hydrostatic pressure on linear momentum balance equations. Also in the present scheme the hydrostatic pressure is successfully eliminated at the element level, leaving only nodal velocities as solution unknowns. A series of 4-node and 8-node quadrilateral elements are derived and examined. Numerical examples demonstrating their characteristic behaviors are also included.The project Supported by National Natural Science Foundation of China     

核壳结构TiO2微球的制备及其光催化性能

以四氯化钛为原料，硫酸铵为分散剂，尿素为前驱物，采用一步溶剂热法成功制备出核壳结构纳米TiO₂微球。通过控制溶剂热温度对TiO₂微球的结构参数(核壳尺寸、晶粒尺寸、比表面积和孔径等)进行调控，并研究样品光催化降解气相苯的性能。结果表明，随着溶剂热温度的升高，微球核壳逐渐分离，中空结构愈发明显，且均为20 nm以下的纳米颗粒组成的二级结构。此类微球比表面积高达265.4 m²/g,孔隙率高达0.247 8 cm³/g,光吸收性能均较P25 TiO₂要高，且光吸收带边出现“蓝移”。核壳结构微球表现出吸附协同光催化降解苯的特性，尤其是180℃下制备的样品光催化活性最高，分析表明，该优异性能得益于其核壳结构对光的充分散射和吸收、优良的结晶度，以及较高的比表面积。     

粒子滤波及其在导航系统中的应用综述

传统的扩展卡尔曼滤波方法要求对非线性系统近似线性化,有可能会引入较大的模型误差.应用粒子滤波解决了这一问题.该算法可以直接应用于原系统的非线性模型当中,并且不需考虑系统噪声和量测噪声是否为高斯白噪声,都能得到很好的滤波效果.文中介绍了粒子滤波的理论基础-贝叶斯估计及具体的实现方式-蒙特卡罗方法;指出粒子滤波存在的退化问题,并从减小退化现象入手将重要性采样和再采样方法引入到算法之中;最后阐述了粒子滤波在导航系统中的一些应用.     

激光陀螺速率偏频系统初始对准方法研究

针对速率偏频激光陀螺转动的工作特性，建立了新的系统误差方程，并在静基座条件下，采用卡尔曼滤波方法实现了系统的初始对准。仿真结果表明，这种初始对准方法对准速度较快，水平对准精度比抖动偏频系统提高了一个数量级，方位对准精度也有较大提高，并且对两个水平加速度计随机常值偏置有很好的估计效果。     

A WEIGHTED PENALTY FINITE ELEMENT METHOD FOR THE ANALYSIS OF POWER-LAW FLUID FLOW PROBLEMS

In this paper,a new finite element method for the flow analysis of the viscousincompressible power-law fluid is proposed by the use of penalty-hybrid/mixed finiteelement formulation and by the introduction of an alternative perturbation,which isweighted by viscosity,of the continuity equation.A numerical example is presented toexhibit the efficiency of the method.     

A PENALTY-HYBRID FINITE ELEMENT ANALYSIS OF STOKES FLOW

A type of penalty-hybrid variational principle is suggested for the analysis ofStokesian flow.On such a basis,a finite element model is formulated featuring,amongothers,a priori satisfaction of the deviatoric stress and hydrostatic pressure on linearmomentum balance equations.Also in the present scheme the hydrostatic pressure issuccessfully eliminated at the element level,leaving only nodal velocities as solutionunknowns.A series of4-node and8-node quadrilateral elements are derived and examined.Numerical examples demonstrating their characteristic behaviors are also included.