一种基于频谱拟合的信号去噪方法

通常我们采用Fourier变换的方法对信号进行去噪 ,本文尝试提出一种新的方法滤除高频噪声与干扰以解决Fourier变换去噪的缺陷 ,在此称为频谱拟合去噪方法。     

Gaussian fitting based optimal design of aircraft mission success space using multi-objective genetic algorithm

In order to obtain the optimized aircraft design concept which meets the increasingly complex operation environment at the conceptual design stage, System-of-systems (SoS) engineering must be considered. This paper proposes a novel optimization method for the design of aircraft Mission Success Space (MSS) based on Gaussian fitting and Genetic Algorithm (GA) in the SoS area. First, the concepts in the design and evaluation of MSS are summarized to introduce the Contribution to System-of-Systems (CSS) by using a conventional effectiveness index, Mission Success Rate (MSR). Then, the mathematic modelling of Gaussian fitting technique is noted as the basis of the optimization work. After that, the proposed optimal MSS design is illustrated by the multi-objective optimization process where GA acts as the search tool to find the best solution (via Pareto front). In the case study, a simulation system of penetration mission was built. The simulation results are collected and then processed by two MSS design schemes (contour and neural network) giving the initial variable space to GA optimization. Based on that, the proposed optimization method is implemented under both schemes whose optimal solutions are compared to obtain the final best design in the case study.     

RS-GIS based morphometrical and geological multi-criteria approach to the landslide susceptibility mapping in Gish River Basin,West Bengal,India

Darjeeling Himalaya is one of the several mountainous areas of India which is often suffered from landslide hazards. In this paper, a multi criteria evaluation is applied using 16 morphometric indicators, geology and lineaments to identify the areas vulnerable in respect to drainage and relief conditions. As both drainage and relief parameters exert strong influences on landslide intensity, both the diversity maps are integrated for final landslide susceptibility mapping. The obtained results show that 20.17?sq.?km (7.61%) area within the basin is highly susceptible for landslides, where average drainage density is 3.78?km/sq.?km, relative relief is greater than 408?m and slope is greater than 12°. The validation result shows that very high landslide susceptible zone is associated with very high frequency of landslide occurrence. Beside this, ROC curve also suggests good predicted rate (86.60%) for the model. So, the proposed method can be applied for predicting landslide susceptible zone.     

飞行员头部特征分析及头型分类方法研究

通过对飞行员进行实地调查,发现目前装备的飞行头盔舒适度并不理想。由此,本文介绍了一种新的头部分析方案,借助光栅投影图像测量技术构建的飞行员头部三维模型,通过数值拟合方法分析获得飞行员的头部特征外形参数。同时按照统计学原理,根据头高、头宽、头长尺寸对飞行员的头型进行了科学地分类。本文描述的外形参数分析方法和头型分类方法可以用在今后大规模飞行员头部特征测量分析以及改进头盔设计的工作中。相关标准对今后头盔设计的改进工作有参考意义。     

某型飞机桨叶平衡孔的喷丸强化技术分析

对飞机铝合金桨叶平衡孔的喷丸强化可以有效提高桨叶的疲劳强度。但在强化过程中必须对喷丸时间、喷丸强度、丸料、覆盖率等因素进行精确控制及优化，以确保达到理想的强化效果，保障飞行安全。     

单点金刚石车削非球曲面测量数据样条拟合算法研究

在分析离散数据插值与逼近方法的基础上,讨论了B-样条拟合算法;并针对超精密非球曲面的测量数据,分析了B-样条拟合算法的拟合误差与阶次的关系,同时与多项式最小二乘拟合做了比较.对比结果表明,B-样条拟合能达到更高的精度,并建议在非球曲面拟合中采用4阶次B-样条、51个控制节点,能达到较好的拟合效果.     

基于动力学的无损检测方法在复合材料桨叶上的应用

基于动力学理论建立了复合材料桨叶结构特性分析及损伤检验的动力学方法。首先通过有限元瞬态分析获取复合材料桨叶在具体边界条件下的工作变形,即ODS;然后运用基于移动矩形窗的最小二乘拟合方法,提取边界层函数因子;最后根据边界层函数及组合的特性变化进行SA349桨叶及直九尾桨的损伤检测,实现了直升机桨叶上损伤位置的有效识别和定位,验证了该方法的有效性。     

极大似然法在飞机极曲线辨识中的应用

介绍了利用极大似然法辨识飞机极曲线的基本原理。通过仿真研究及对实测飞行试验数据的处理，表明该方法能够辨识出光滑的非线性飞机极曲线，算法具有良好的收敛性及结果的唯一性，并且可方便地推广应用于工程中其它类型的非线性曲线辨识问题。     

Analysis Approach to Durability Based on Material Initial Fatigue Quality and S-N Curve

Based on probabilistic fracture mechanics approach, a new concept of material initial fatigue quality (MIFQ) is developed. Then, the relation between S-N curve and crack propagation curve is studied. From the study, a new durability analysis method is presented. In this method, S-N curve is used to determine crack growth rate under constant amplitude loading and evaluate the effects of different factors on durability and then the structural durability is analyzed. The tests and analyses indicate that this method has lower dependence on testing, and higher accuracy, reliability and generality and is convenient for application.     

火箭橇水刹车戽斗入水运动的阻力预测

火箭橇水刹车戽斗作为火箭橇高速试验的减速装置,附加质量较大,运行速度快,在利用水的冲击作用减速时,承受很大的载荷。为了确保火箭橇水刹车戽斗的安全,同时达到预期的减速效果,对火箭橇水刹车戽斗的运动情况进行数值仿真分析。借助Abaqus中的流固耦合技术,通过CEL方法对火箭橇水刹车戽斗入水运动情况进行分析,得到火箭橇水刹车戽斗在多种不同运动情况下的阻力曲线,并根据流体阻力理论计算公式,拟合出该火箭橇水戽斗入水的流体阻力计算公式。利用该公式可对该火箭橇水刹车戽斗在不同速度、不同初始水位高度下所受的阻力进行预测。