长边条翼身融合过渡曲面的构造方法

 针对飞航导弹长边条翼身融合过渡曲面的构造展开研究,为满足融合过渡曲面过渡线能够由设计人员确定和长边条面必须是等截面的直纹面等要求,综合应用基于局部重新参数化构造过渡曲面和基于物理的能量曲面造型构造过渡曲面方法,并结合导弹弹身曲面是等截面直纹面的特点,通过构造翼身融合面、长边条面和头锥面3张曲面拼接来构造G-1连续的长边条翼身融合过渡曲面。提出了预先构造中间辅助面和辅助基曲面的方法,通过辅助基曲面和弹翼面上重新参数化局部基曲面间线性组合来构造翼身融合面。通过使中间辅助过渡面的边界切矢与弹身的纵向切矢一致,来保证长边条面与翼身融合面间的G-1连续性。最后利用基于物理的能量曲面造型方法构造与弹身和长边条面G-1连续的头锥过渡面。     

基于局部方法的余度惯性组件故障诊断

介绍了局部方法(local approach)原理及其在随机系统故障诊断中的应用问题,讨论了用于故障诊断的样本数目对检测性能的影响,指出通过增加样本数目,可以大大增加局部方法检测小故障的能力,并说明样本数为1时,广义似然比(GLR,Generalized Likelihood Ratio)方法和局部方法的判决函数相同.为了验证所提出方法的有效性,将局部方法用于沿正十二面体对称侧面配置的冗余微机械惯性组件(IMU, Inertial Measurement Unit)故障检测,实验结果表明文中的理论分析是符合实际情况的.      

Navier-Stokes方程两层稳定有限元算法分析

分析了定常Navier-Stokes方程的两种两层稳定有限元算法。它们将局部Gauss积分稳定化技术和两层算法的思想充分结合,采用低次等阶有限元P1-P1或Q1-Q1对N-S方程进行数值求解。误差分析和数值算例结果表明,当粗、细网格尺度H=O（h1/2）时,它们与在细网格上的单层有限元算法具有相同的收敛速度,而两层算法却节省了大量的计算时间。相比之下,Simple算法具有更高的计算效率。而且进一步发现Oseen算法能够对小粘性系数N-S方程进行有效求解。     

地方高职院校大学生网络素质调研与分析

通过对某高职院校大学生网络使用情况进行问卷和走访调研，详细统计地方高职院校大学生网络行为的数据，分析和总结地方高职院校大学生网络素质的现状。     

局部弯矩对复合材料结构连接区的影响

本文选取部分不同连接形式的复合材料连接试验,首先按一般结构强度设计时将连接区视为理想化的模型预算结构破坏模式及最大承载值,再结合试验结果分析不同连接形式中影响破坏的关键原因,相互比较,寻求较合理的复合材料连接形式,避免复合材料结构连接设计中的不足。     

共享内存网--面向飞机仿真的实时网络

将多台计算机连接起来,共同完成单个的实时任务,如飞机仿真是一项非常具有挑战性的工程任务。本文论述了计算机分布式仿真的一些独特要求,对目前使用的两种主要方法进行了总结,将共享内存网的概念和传统的方法进行了对比介绍,共享内存网的设计方法、性能参数以及详细的设计过程也有论述。     

Airfoil Aeroelastic Flutter Analysis Based on Modified Leishman-Beddoes Model at Low Mach Number

Based on modified Leishman-Beddoes (L-B) state space model at low Mach number (lower than 0.3), the airfoil aeroelastic system is presented in this paper. The main modifications for L-B model include a new dynamic stall criterion and revisions of normal force and pitching moment coefficient. The bifurcation diagrams, the limit cycle oscillation (LCO) phase plane plots and the time domain response figures are applied to investigating the stall flutter bifurcation behavior of airfoil aeroelastic systems with symmetry or asymmetry. It is shown that the symmetric periodical oscillation happens after subcritical bifurcation caused by dynamic stall, and the asymmetric periodical oscillation, which is caused by the interaction of dynamic stall and static divergence, only happens in the airfoil aeroelastic system with asymmetry. Validations of the modified L-B model and the airfoil aeroelastic system are presented with the experimental airload data of NACA0012 and OA207 and experimental stall flutter data of NACA0012 respectively. Results demonstrate that the airfoil aeroelastic system presented in this paper is effective and accurate, which can be applied to the investigation of airfoil stall flutter at low Mach number.     

Bifurcation in a 3-DOF Airfoil with Cubic Structural Nonlinearity

Limit cycle oscillations (LCOs) as well as nonlinear aeroelastic analysis of a 3-DOF aeroelastic airfoil motion with cubic restoring moments in the pitch degree of freedom are investigated.Aeroelastic equations of an airfoil with control surface in an incompressible potential flow are presented in the time domain.The harmonic balance (HB) method is utilized to calculate the LCO frequency and amplitude for the airfoil.Also the semi-analytical method has revealed the presence of stable and unstable limit cycles,along with stability reversal in the neighborhood of a Hopf bifurcation.The system response is determined by numerically integrating the governing equations using a standard Runge-Kutta algorithm and the obtained results are compared with the HB method.Also the results by the third order HB (HB3) method for control surface are consistent with the other numerical solution.Finally,by combining the numerical and the HB methods,types of bifurcation,be it supercritical,subcritical,or divergent flutter area are identified.     

预测控制综合设计算法设计及软件实现

预测控制综合设计方法通过设计一组满足特定要求的终端约束条件来保证系统的稳定性.给出了一组满足该要求的终端约束条件,然后依据多参数二次规划法求解预测控制器的基本思路,在Matlab环境下设计并实现了一个预测控制综合方法的控制器求解软件,最后通过一个仿真实验验证了该软件的基本功能.仿真结果表明,所设计的软件可以用于求解基于...     

局部应变法预测飞机结构带孔部件疲劳寿命

介绍了应用Levenberg-Marquardt迭代法计算局部应力和局部应变的工作.Levenberg-Marquardt迭代法是求解超越方程的一种常用数学方法,但是缺点是程序比较复杂,计算效率较低,因此本文目的是找到一种程序实现简单、计算效率高、计算精度满足要求的计算方法,选择了二分法,并且对比分析了二分法和Leve...