共查询到20条相似文献,搜索用时 62 毫秒
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研究高斯径向基核支持向量回归机参数优化问题。推导线性和非线性支持向量回归机公式,分析影响支持向量回归机精度的主要控制参数,将拉丁超立方设计方法与Powell法相结合,提出一种快速有效的支持向量回归机参数优化方法。将支持向量回归机用于近似建模,提供仿真算例,并与Kriging函数和径向基函数近似性能进行比较。结果表明,设计的支持向量回归机能实现近似精度和近似效率的良好折中,参数估计简单,易于编程实现,是有效的近似建模方法,可为飞行器多学科设计优化用近似建模方法研究提供理论参考。 相似文献
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基于纹理特征和支持向量机的葡萄病害的识别 总被引:7,自引:0,他引:7
针对葡萄病害彩色纹理图像的特点,提出一种将支持向量机和色度矩分析应用于葡萄病害识别的方法.首先利用色度矩提取葡萄病害叶片纹理图像的特征向量,然后将支持向量机分类方法应用于病害的识别.葡萄病害纹理图像识别实验结果表明,利用色度矩提取病害彩色纹理图像特征简便、快捷、分类效果好;支持向量机分类方法对于病害分类训练样本较少时,具有良好的分类能力和泛化能力,适合于葡萄病害的分类.不同分类核函数的相互比较分析表明,径向基核函数最适合于葡萄病害的分类识别. 相似文献
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针对支持向量机核函数和控制参数选取难度较大的问题,提出了一种主动划分参数区间的双尺度径向基核支持向量机,并用并行定向变异混合粒子群优化算法选取其控制参数。试验分析了利用标准数据集经多次独立重复试验得到的均值等统计量,验证、测试了上述支持向量机模型,同时考虑了类间数据不平衡的影响。结果表明,双尺度径向基核函数的性能在多数情况下优于单径向基核函数,并行定向变异的混合粒子群优化算法优于标准粒子群优化算法,能够有效抑制早熟收敛,有利于搜索到更优的支持向量机控制参数。 相似文献
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提出一种集合经验模式分解(Ensemble empirical mode decomposition,EEMD)和支持向量机(Support Vector Machine,SVM)的故障诊断模型。采集机电系统的振动信号,进行小波降噪处理后,对其进行集合经验模式分解,得到若干具有物理意义的本征模态函数(Intrinsic mode function,IMF)并计算其能量分布。以能量分布构造特征矢量,采用遗传算法对SVM参数进行寻优,建立径向基核函数支持向量机模型进行多类故障分类。将该方法应用于转子实验台的故障诊断研究中,实验结果表明,该方法能够有效地运用于机电系统的故障诊断中。 相似文献
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为了提高光伏发电预测的精度,提出基于支持向量机和深度信念网络的光伏发电预测方法。利用改进的相似日算法选择相似日训练样本,分别构建以线性核函数、多项式核函数、高斯径向基核函数为核函数的支持向量机预测模型作为组合预测模型中的单项模型,再将三种单项模型的预测结果作为深度信念网络的输入,利用深度信念网络对三种单项模型的预测结果进行组合优化输出,根据实际输出与期望输出的误差动态调整组合权值,从而获得更高的预测精度。最后以澳大利亚沙漠太阳能研究中心的实测数据进行仿真验证,仿真结果表明,所提方法相较于其他方法具有较高的预测精度。 相似文献
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由于支持向量机中的参数会显著影响着支持向量机分类的精确度,建立了一种基于免疫算法优化最小二乘支持向量机的电力变压器故障诊断模型;该模型以变压器油中主要溶解气体作为向量机的输入,以变压器故障类型作为其相应的输出,选用径向基核、使用免疫算法得到优化参数,充分发挥向量机较高泛化能力的优势.实例验证表明,这种方法能提高变压器的故障诊断准确率,反映了其有效性和正确性. 相似文献
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Clarence W.DE SILVA 《Instrumentation》2019,(4):72-84
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... 相似文献
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INTEGRAL EQUATION METHOD'S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES 总被引:1,自引:0,他引:1
LI Cheng ZHENG Yanping 《机械工程学报(英文版)》2008,21(6):115-118
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. 相似文献
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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. 相似文献
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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... 相似文献
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分布动态载荷识别的抗噪处理 总被引:2,自引:2,他引:0
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. 相似文献
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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。 相似文献
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The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar... 相似文献
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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.... 相似文献
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J. A. Williams 《Lubrication Science》1997,3(3):267-306
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. 相似文献
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CHEN Sunyi 《机械工程学报(英文版)》2007,20(6):13-17
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. 相似文献