AP聚类改进免疫算法用于航空发动机故障诊断

在免疫算法训练过程中引入近邻传播(AP)聚类与熵权法,对训练样本进行聚类与权值计算,将权值引入免疫算法中样本选择阈值的计算,以解决训练过程采用固定选择阈值所造成的检测器在部分区域过拟合,部分区域欠拟合的问题。结果表明:改进的免疫算法用于典型非线性函数的寻优时,迭代性能均优于传统免疫算法,并在大部分情况下优于粒子群算法与量子遗传算法,在进行某型发动机故障诊断的实例实验时,改进后的算法的诊断准确率达到98.06%,高于传统免疫算法的92.60%。      

实物标准电阻器智能输出系统的研究

针对实物电阻器输出阻值的改变只能通过手动方式实施的问题,设计了一套智能控制系统,实现实物电阻器阻值的数字化输出。将多只四端标准电阻器以一定的排列顺序串联连接,利用四端标准电阻器的原理特点,所有串联电阻共用一对电位端,在每只电阻器的左右分别都有一个电流输出端,电流输出端线路中接入继电器控制开关,以控制继电器的开通闭合,来实现电阻器的不同组合输出。本系统经试用,性能稳定、准确度高、实时性好、适用范围广、试运行情况良好。     

一种基于观测站数目最小化的TDOA/FDOA无源定位算法

在三维（3D）运动目标无源定位系统中，无模糊定位最少需要4个观测站。而传统的两步加权最小二乘（TSWLS）及其改进的闭式算法至少需要5个观测站进行求解，当减少一个观测站时，这些闭式算法往往无法提供可靠解。针对这一问题，提出一种最小化观测站数目的到达时间差（TDOA）与到达频率差（FDOA）定位算法。该算法是一种闭式解法并且能够在三维场景下仅使用4个观测站进行定位。该算法分为两步：第1步分离传统的TSWLS算法中未知参数空间，建立了一组新的等式，并且利用加权最小二乘（WLS）算法得到目标位置与速度的初始值；第2步利用泰勒级数展开算法将中间变量线性化，对目标位置和速度初始值进一步校正。理论分析证明了在适当的噪声水平下该算法能够达到克拉美罗界（CRLB）。此外，计算机仿真表明仅使用4个观测站时，该算法对于近场以及远场目标参数的估计精度在测量噪声较小时可以实现CRLB；并且还表明使用5个观测站估计时，该算法比TSWLS及其改进算法能更好地适应大的测量噪声。     

基于点云数据的发动机管路最小间距计算方案

为检测整机发动机管路是否满足最小间距的设计要求,提出了一种基于点云数据的发动机管路最小间距计算方案,方案包含5个步骤:①从点云数据中划分出不同管路的数据;②基于管路点云数据的空间分布构造等间隔栅格,计算栅格中心点作为管路的趋势线数据;③在管路各趋势线数据点位置上构造垂直平面,将管路点云数据投影到最近的垂直平面上,获得各个垂直平面上呈圆弧状分布的投影点数据;④对各垂直平面上的投影点数据进行最小二乘圆拟合,得到拟合圆圆心及其半径值,将拟合圆圆心作为管路中心线数据;⑤采用遍历法计算两条管路中心线数据的最小间距,中心线最小间距分别减去两条管路的半径值则得到两条管路的表面最小间距。通过12条管路验证了方案的准确度。实验结果表明:管路最小间距偏差在-0.35~0.46mm之间,管路半径偏差在-0.08~0.22mm之间。该方案的实施有助于管路间距数字化检测的实现,且方案的计算结果具有较好的鲁棒性。      

运输机机翼平面参数快速优化方法

提出了一套机翼平面参数快速优化方法。新方法通过改变优化思路,简化计算模型,合理选择计算方法,有效地提高了优化效率。简要介绍参数优化思想与流程控制,重点阐述优化程序的气动、重量与性能计算模块的算法。以某运输机为算例,优化结果与资料数据吻合,验证了新方法的正确性。     

TEC differences for the mid-latitude ionosphere in both sides of the longitudes with zero declination

Based on measurements of ground-based GPS station network, differences of the mid-latitude ionospheric TEC in the east and west sides of North America, South America and Oceania have been analyzed in this paper. Results show that for nearly all seasons from 2001 to 2010 and in both sides of the longitudes with zero declination, there exist systematic differences for the mid-latitude ionospheric TEC in the regions mentioned above and the features of these differences markedly depend upon the local time but less depend upon seasons and the level of solar activity. Theory analysis shows that the longitude variations of both declination and zonal thermospheric winds are one of important factors to cause differences of the mid-latitude ionospheric TEC in both sides of the longitudes with zero declination.     

Effects of yaw-roll coupling ratio on lateral-directional aerodynamic characteristics

Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide different coupled motions from low to high angles of attack.A parameter ‘‘coupling ratio" was introduced to indicate the extent of yaw-roll coupling. At each pitch angle, seven coupling ratios were designed to study the yaw-roll coupling effects on the lateraldirectional aerodynamic characteristics systematically. At high angles of attack, the damping characteristics of yawing and rolling moments drastically varied with coupling ratios. In the coupled motions with the rotation taking place about the wind axis, the lateral-directional aerodynamic moments exhibited unsteady characteristics and were different from the ‘‘quasi-steady" results of the rotary balance tests. The calculated results of the traditional aerodynamic derivative method were also compared with the experimental data. At low and very high angles of attack, the aerodynamic derivative method was applicative. However, within a wide range of angles of attack, the calculated results of aerodynamic derivative method were inconsistent with the experimental data, due to the drastic changes of damping characteristics of lateral-directional aerodynamic moments with yaw-roll coupling ratios.     

平台式重力仪航空重力测量数据后处理技术研究

针对航空重力测量对数据后处理的要求,结合平台式重力仪系统的组成与工作原理,在重力异常信号的频域特征基础上,设计出一套有严格频域规范的航空重力数据后处理流程,并对某海域实测数据进行了处理。结果表明,重力异常值内符合精度为12条东西测线达到0.43mGal/140s和0.84mGal/100s,4条南北测线达到0.39mGal/140s和0.79mGal/100s;以同测线GT-2A单次测量结果为标准值统计标准差,12条东西测线为0.72mGal/140s和0.98mGal/100s,4条南北测线为1.41mGal/140s和1.53mGal/100s。结果表明,设计的航空重力测量数据后处理方法可以实现重力异常信号的高精度提取。     

变体辅助的无人机栖落机动模糊控制设计

无人机（Unmanned aerial vehicle， UAV）的栖落机动是一种大幅度的俯仰运动，易引起升降舵操纵力矩饱和。本文以变体方式增强无人机的俯仰操纵能力，并研究其对应的控制设计方法。首先对栖落机动建立了纵向动力学模型，并通过采用轨迹线性化和张量积变换方法转换得到T-S模糊模型。基于Lyapunov稳定理论和平方和方法，设计了满足控制输入约束的栖落机动多项式模糊控制器。对非变体与变体下的栖落机动控制过程进行了仿真，结果验证了控制律的有效性，并且表明变体辅助的无人机具有更强的操纵性能，能提高栖落机动中升降舵的抗饱和能力。     

Design and analysis of a truss deployable antenna mechanism based on a 3UU-3URU unit

Space deployable structures with large calibers, high accuracy, and large folding ratios are indispensable equipment in the aerospace field. Given that the single-DOF 3RR-3RRR deployable unit cannot be fully folded, this study proposes a 3UU-3URU deployable unit with two kinds of DOF: folding movement and orientation adjustment. First, based on the G-K formula, the DOF of the 3UU-3URU unit is analyzed. Then, the 3UU-3URU unit is used to construct a deployable truss antenna with a curved surface, and the DOF of the whole deployable antenna containing multiple 3UU-3URU units is calculated. The structural design of a deployable antenna with two loops is carried out with specific parameters and geometric relations. Next, a DOF simulation of a basic combination unit composed of three 3UU-3URU units is performed. Finally, a prototype of the basic combination unit is manufactured, and the DOF of the mechanism is experimentally verified.