FERA in parameter identification with application in low speed wind tunnel test

This paper presents a new approach which consists of a fuzzified eigensystem realization algorithm (FERA) to identify the parameters of the designed mini-UAV model performance in the low speed wind tunnel (LSWT) power on testing system. On the basis of the identification scheme, it is able to reduce system operational cost of wind tunnel tests and provide a tool for predicting results without resorting to on-site experiments. A variety of variables in model types and testing environment such as model profile, angle of attack, elevator, tunnel wind speed and power system (motor and propeller) are considered. The method based on logic devices is simple yet effective. The results obtained are compared to those obtained by the conventional wind-tunnel testing method. To verify effectiveness of the proposed methodology, both of simulations and real-world experiments are conducted. The results show that the working performance of the proposed method correlates well with expectation.     

飞机后缘襟翼运动同步性设计和计算

在飞机的起飞、降落、巡航飞行中,襟翼运动起着重要的作用.全机有多块内、外襟翼,当分别绕各自不同的转轴运动时,会产生不同的圆锥运动.为实现所有的内、外襟翼同步运动,需对每块襟翼上的不同作动器进行精心设计、布局,及对作动器运动参数进行计算.这既非常关键,又相当复杂,一直是设计中的难题.介绍了现代客机襟翼作动器运动学计算方法...     

高校“双困”毕业生就业难点及就业对策探析

高校"双困"毕业生是就业的特殊群体,要实现"双困"毕业生的充分就业,国家应该从政策上加大扶持力度;高校要有针对性地进行专业技能拓展、心理健康教育和就业指导,提高学生的综合素质能力;"双困"生也应认清就业形势,转变观念,培养自身能力,提升就业竞争力。只有从多方面入手,才能最终达到充分就业的目的。     

一种用于高速数据采集系统的无损压缩方法

提出了一种应用于电子装备多通道数字信号高速采集与存储系统的无损压缩方法.该方法具有实现简单、压缩率高的特点.在高速数据采集系统的实际应用中,该方法能将海量采样数据压缩至原来的25%左右而不影响系统的处理速度,验证了该压缩方法的有效性和实用性.     

千兆赫横电磁室（GTEM）的原理和计算方法

GTEM是几年前才发明的EMC/EMI测量装备,具有很大的重要性。文章重点论述以下几个问题:(1)传统的横电磁传输室(TTC)的缺点;(2)GTEM的原理及可能达到的技术指标;(3)特性阻抗的无穷级数公式;(4)对特性阻抗进行编程计算的方法,以及计算实例。最后,讨论了准静态分析所存在的问题,从而明确了进一步研究的方向。     

Numerical investigation on the shock wave transition in a three-dimensional scramjet isolator

The scramjet isolator, which is used to prevent the hypersonic inlet from disturbances that arise from the pressure rise in the scramjet combustor due to the intense turbulent combustion, is one of the most critical components in hypersonic airbreathing propulsion systems. Any engineering error that is possible in the design and manufacturing procedure of the experimental model, and the intense heat release in the scramjet combustor, may cause the performance of the isolator to decrease, leading to its lack of capability in supporting the back pressure. The coupled implicit Reynolds Averaged Navier–Stokes (RANS) equations and the two-equation standard k?ε turbulent model have been employed to numerically simulate the flow fields in a three-dimensional scramjet isolator. The effects of the divergent angle and the back pressure on the shock wave transition and the location of the leading edge of the shock wave train have been estimated and discussed. The obtained results show that the present numerical results are in very good agreement with the available experimental shadow-pictures, and the numerical method is more suitable for capturing the shock wave train and predicting the location of the leading edge of the shock wave train in the scramjet isolator than the present two-dimensional numerical methods. This is due to the small width-to-height ratio of the isolator and the intense three-dimensional flow structures. On increasing the divergent angle of the scramjet isolator, the static pressure along the central symmetrical line of the isolator decreases sharply. This is due to the strong expansion wave generated at the entrance of the isolator, and when the divergent angle of the isolator is sufficiently large, namely 1.5°, a zone of negative pressure is formed just ahead of the leading edge of the shock wave train. At the same time, the shock wave train varies from being oblique to being normal, and then back to oblique. With an increase in the prescribed back pressure at the exit of the scramjet isolator, the leading edge of the shock wave train moves forward towards the entrance of the isolator, and when the back pressure is sufficiently large, unstart conditions in the hypersonic inlet can take place if the shock train reaches the inlet.     

强5E型飞机颤振特性分析

根据强5飞机以往型号的颤振计算结果，对强5E型飞机的两种外挂状态（全机＋2×LS－500J激光弹。全机＋2×LS－500J激光弹＋2×4001副油箱）作了颤振特性分析。     

大迎角体涡,翼涡干扰的Euler方程数值模拟

本文用Ｅｕｌｅｒ方程的简化区算法计算翼－身组合体绕流。当大迎角时，计算能自动捕捉到大后掠前缘的分离涡，机射的分离涡由强加Ｋｕｔｔａ条件生成，形成体涡与翼涡的相互干拢。本文对加长前机身的ＡＧＡＲＤ－Ｂ翼－射组合体模型，给出机射有分离和无分离时，横流截面的速度矢量分布、法向力和压力中心，分析体涡的影响。     

定标系统光源控制电路设计

文章介绍了某型号定标系统光源控制电路的设计。     

The accuracy of ionogram-derived N(h) profiles

At the Millstone Hill station the Incoherent Scatter Radar (ISR) and a Digisonde 256 are simultaneously operating. Some characteristic true heights determined by both instruments are compared with each other, possible reasons for observed difference are indicated.