基于聚类离群因子和相互密度的离群点检测算法

针对大多基于聚类的离群点检测算法往往需要人工输入参数,对于不同的数据集很难选择一个合适参数的问题,将无参数的基于自然邻居的离群点检测算法的自然邻居搜索算法和密度峰值聚类算法相结合,提出一种基于聚类离群因子和相互密度的离群点检测算法。该算法使用相互密度和γ密度构造决策图,将γ密度异常大的样本点作为聚类中心进行聚类,最后根据聚类的离群因子找出离群聚类边界检测离群点,该算法不需要人工输入参数。在模拟数据集和真实数据集下进行了实验,证明了所提算法能很好地进行聚类和离群数据的挖掘。     

基于累积全熵的子空间聚类离群点检测算法

针对累积互信息方法存在的最佳聚类子空间选择不稳定和计算复杂的问题,给出累积熵的链式法则、累积全相关、累积全熵的计算方法,采用累积全熵在连续数据集上挖掘最佳聚类子空间,并在最佳聚类子空间中进行离群点挖掘,提出基于累积全熵的子空间聚类离群点检测算法。分别在真实数据集和虚拟数据集上验证了所提算法的有效性和可伸缩性。实验表明,所提算法进一步提高了子空间离群点的挖掘效率。     

基于聚类和距离的大数据集离群点检测算法

针对已有的基于距离的离群点检测算法在大数据集上扩展性差的问题,提出了基于聚类和距离混合的大数据集离群检测算法.算法第一阶段采用层次聚类和k-means混合的层次k-means算法对数据进行聚类,并按照一个启发式规则对其进行排序.第二阶段在聚类的结果上采用嵌套循环算法进行离群检测,并通过两个剪枝规则进行高效舅枝,减少了离群检测时数据点之间距离计算的次数.理论分析和实验结果证明了算法的可行性和效率.     

基于分式聚合过程神经网络的发动机气路参数偏差值预测

为解决航空发动机气路参数偏差值时间序列中突变值难以预测的问题,基于有理式函数具有更好的非线性逼近能力的理论,提出一种分式非线性聚合过程神经网络模型.该网络结构在隐层中存在一个过程神经元对偶层,通过分式非线性空间聚合的方式,分别实现信号对神经元的激励和抑制作用.根据采样点离散化的特点,采用离散Walsh变换对的内积运算替代积分算子,在简化计算过程的同时消除了数据拟合中的精度损失.采用基于离散Walsh变换LM算法进行网络训练,将训练好的模型应用在气路参数偏差值时间序列预测中.从预测结果可以看出,该模型对存在突变值的时间序列预测具有更高的效率和灵敏性.     

水洗对航空发动机性能影响分析

基于发动机监控参数EGTM,将收集的水洗样本数据通过MATLAB软件采用了箱型法和三次指数平滑法对原始数据进行了粗大误差去除和平滑处理,然后采用奇异值分解SVD将数据中的波动干扰分离开来,研究分析了积垢对航空发动机性能的影响。然后,运用插值函数Spline将水洗点通过一条平滑的曲线连接起来,研究分析了水洗对因积垢导致发动机性能衰退的作用并得出结论。最后对水洗时机做了简易评估。     

Rolls-Royce发动机基线挖掘方法

采用基于核函数的多元非线性回归分析方法,对Rolls-Royce公司的发动机基线方程进行了求解,建立了标准化过程中的核函数和性能参数的偏差值模型.把厂家系统计算出的偏差值作为目标值,其他相关参数的测量值作为输入,采用高斯牛顿迭代法对该多元非线性方程组进行回归分析,能够迅速收敛,准确地求解出模型未知系数,经整理可得出准确的基线方程.通过比较自主基线求解的偏差值与厂家系统求解的偏差值可知,采用上述基线挖掘方法得到的基线方程模型精度能够满足实际应用的要求.     

一种结合高斯统计的点云引导滤波算法

针对三维信息采集设备得到的点云中含有噪声点会影响观测和重建的问题,提出一种结合高斯统计的引导滤波方法用于点云去噪和平滑处理。首先通过计算点云中各点与邻域点的欧式距离及其均值和标准差设置高斯分布阈值去除离群点,然后采用引导滤波算法平滑模型表面噪声点。仿真实验展示了不同参数下高斯统计方法去除离群点的效果,将点云引导滤波分别与均值滤波、双边滤波进行对比,结果表明点云引导滤波具有良好的几何特征保持性能和算法耗时低的优点。     

基于法向修正的双边滤波点云去噪处理

为了在降噪的同时保持点云模型的几何特征,并较好地处理离群点,针对不同种类的噪音问题,提出了一种基于法向修正的双边滤波点云综合去噪算法。该算法先对点云模型进行空间单元格划分,构造基于单元格最佳连通域,保留内部点云数据并去除点云模型离群点,然后根据双边滤波需要求法线的特点,对点云模型进行法向修正后再进行滤波处理。实验结果表明该算法简单快捷,能够很好地去除离群点,在去噪的同时可以很好地保留点云模型的几何特征,在处理效率和稳定性方面均优于单一的双边滤波算法。     

SVR在航空发动机基线挖掘中的应用研究

针对航空发动机基线难以获取的问题,利用支持向量回归机(support vector regression,SVR)算法,采用厂家监控系统数据和飞机快速存储记录器(quick access recorder,QAR)数据两种方式对基线进行挖掘分析,提供了获取基线的多种途径和方法,取得了比较可靠的结果。支持向量回归机在处理非线性回归分析时具有快速、准确的优点,能够进行单参数及多参数的基线回归分析,通过计算结果比较分析,多参数基线回归与单参数基线回归、一元线性基线拟合相比具有偏差小、精度高的优势,能够有效提高发动机基线监控的准确性。     

保持特征的散乱点云数据去噪

为保证在去除点云数据噪声的同时不损失模型的细节特征,提出了一种基于特征信息的加权模糊C均值聚类去噪算法。首先,构建点云K-D树拓扑结构,根据点的r半径球邻域点统计特性去除大尺度离群噪声点。然后,利用主元分析法估算点云的曲率和法向量,根据曲率特征标识点云数据的特征区域,并采用特征加权模糊C均值聚类算法对特征区域去噪,采用加权模糊C均值聚类算法对非特征区域去噪。最后,使用双边滤波器对点云模型进行平滑。对提出的算法进行了验证实验,结果显示:去噪后点云模型的最大偏差保持在模型尺寸的0.15%以内;标准偏差保持在模型尺寸的0.03%以内。本文算法能够在有效去除不同尺度和强度的噪声的同时不损失点云模型的细节特征,去噪精度高,且对不同的噪声模型具有较强的鲁棒性。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.