一种针对局部结构的有限元模型修正方法

针对实际结构有限元模型（FEM）的建模误差通常仅存在于局部区域，提出了一种对局部结构单独进行模型修正的方法。首先，根据频响函数（FRF）解耦理论得到由残余结构频响函数与包含待修正参数的局部结构动刚度所重构的整体结构频响函数的拟合值，然后通过迭代优化使其与测量值的残差最小化，从而得到参数的极大似然估计。在此基础上，将残差关于参数的灵敏度以局部结构动力学矩阵表示，建立了模型修正的基本方程，利用整体结构的测试数据即可直接对分离出来的局部结构进行模型修正。最后，对喷气式飞机和三角机翼飞机分别进行了数值模拟和实验研究，验证了所提方法的可行性和有效性。结果表明，所提方法可以成功地用于仅局部区域含有建模误差的实际结构有限元模型的修正，修正后的有限元模型的动态特性与实际结构有较好的一致性。     

一种高动态低信噪比卫星导航信号捕获方法

为提升高动态低信噪比环境下卫星导航信号的捕获性能,提出了一种基于分数阶傅里叶变换(FrFT)及部分匹配滤波(PMF)的捕获方法。在该方法中,接收机首先利用PMF对接收信号做分段相干积分,随后借助快速傅里叶变换(FFT)对分段积分结果做离散快速FrFT,最后通过检测FrFT输出的峰值完成信号的捕获。由于具有多普勒频率变化率的卫星导航信号在FrFT后呈现能量聚焦特性,所提方法能够显著提高信号的长时间相干积分增益。同时对所提算法的捕获概率、平均捕获时间以及算法复杂度等性能指标进行了理论分析及计算机仿真验证。仿真表明,与传统的PMF-FFT方法相比,所提方法能够通过延长相干积分时间的方式有效提升高动态低信噪比卫星导航信号的捕获概率、降低捕获时间。     

An innovative approach for integrated airline network and aircraft family optimization

The determination of optimal aerial transport networks and their associated flight frequencies is crucial for the strategic planning of airlines, as well as for carrying out market research, to establish target markets, and for aircraft and crew rostering. In addition, optimum airplane types for the selected networks are crucial to improve revenue and to provide reduced operating costs. The present study proposes an innovative approach to determine the optimal aerial transport network simultaneously with the determination of the optimum fleet for that network, composed of three types of airplanes (network and vehicle integrated design). The network profit is maximized. The passenger’s demands between the airports are determined via a gravitational model. An embedded linear programming solution is responsible for obtaining potential optimal network configurations. The optimum fleet combination is determined from a database of candidate aircraft designs via genetic algorithm. A truly realistic airplane representation is made possible thanks to accurate surrogate models for engine and aerodynamics is adopted. An accurate engine deck encompassing a compression map and an innovative engine weight calculation besides an aerodynamical artificial neural network module enable a high degree of accuracy for the mission analysis. The proposed methodology is applied to obtain the optimum network comprised of twenty main Brazilian airports and corresponding fleet.     

基于小波变换的图像低通去噪

提出了一种利用小波变换的多分辨率特性对图像进行低通去噪的方法,系统的阐述了其基本原理和核心算法,并对加噪后的图像实现了低通去噪处理。     

J—7LP飞机1：6遥控模型失速尾旋试验

对无动力J—7LP动力学缩比模型进行了遥控试飞,以研究其失速尾旋特性,全偏平尾和方向舵可使模型进八尾旋,舵面全回中即可从各种尾旋中改出。偏转副翼对尾旋特性有明显的影响。     

减少机床噪声污染的方法

噪声污染已成为世界三大污染之一.在工业企业中机床噪声是重要的噪声污染源之一.本文主要从机床的齿轮传动、轴承的选用和齿轮箱的结构等方面对机床噪声产生的影响以及提出相应的降噪措施进行了探讨.从而降低机床噪声,保障工人身心健康,改善车间工作环境.     

Digital Aircraft Sheet Metal Part Manufacturing System and Its Key Technology

The architecture of digital sheet metal manufacturing system is proposed based on the classification of sheet metal manufacturing information.The essence of digital manufacturing is the definition,management and transfer of information,and the key technologies are brought forward and described.It is pointed out that knowledge-based manufacturing elements design is necessary to make digital technology efficient.The management of all kinds of sheet metal manufacturing element information is to build single source of manufacturing data.Multi-state model-based digital transfer and coordination method is designed to provide a foundation for digital manufacturing of aircraft sheet metal part.The application of digital sheet metal manufacturing is exemplified with an aircraft sheet metal part.The application result is compared to that of the traditional analog transfer technology.It is shown that the developed technology can improve part quality,shorten manufacturing time and lower manufacturing cost.     

逆升压电子设备冷却系统控制方案的研究

分析了目前国内一些飞机基于三点温度控制方案的逆升压电子设备冷却系统的缺陷 ,提出了一种新的系统控制方案 ,即基于飞行速度和高度的逆升压电子设备冷却系统的控制方案。这一方案不需要人工干预 ,可实现全自动化。     

鲁棒变结构制导规律研究

研究存在相对速度测量噪声时的鲁棒制导问题，根据一类变结构制导规律，分析了相对速度测量噪声、制导参数对导引收敛性的影响，以弹道收敛为准则，给出了实现鲁棒制导的条件，研究结果对设计先进的雷达制导系统具有重要意义。     

回转体头部空化噪声特性的实验研究

为了分析回转体头部空化噪声特性,利用高速水洞实验室对实验测得的回转体圆头头体、平头头体模型空化噪声的谱特性进行了测量。测量结果表明:在空化形态不变的条件下,空化噪声宽带谱级将随空泡数的减小而单调增加;随着空化的发展,其空化噪声谱的低频段升高,而高频段的噪声则相对下降;在空泡数基本相同的条件下,模型空化噪声的宽带谱级和谱形基本相同。