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基于非线性时序模型盲辨识的因子隐Markov模型识别方法 总被引:1,自引:1,他引:1
基于模型辨识的机械有效故障特征提取方法中输入信号难以确定,以及机械设备运行过程中具有信息量大、非平稳、特征重复再现性差的特点,结合非线性时序模型盲辨识和因子隐Markov模型,提出一种基于非线性时序模型盲辨识的特征提取的因子隐Markov模型识别方法,并应用到旋转机械升降速过程故障诊断中.同时还与基于Fourier变换、小波变换的特征提取的因子隐Markov模型识别方法进行比较,试验结果表明该方法是有效的. 相似文献
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本文讨论了用ARNAX时间序列模型来辨识液压系统的阶和参数,同时得到系统的干扰噪声模型。文中提出的增广最小二乘法和BIC定阶准则的结合,比已有方法辨识参数和阶的精度要高。进一步根据估计参数的渐近正态性确定模型的子阶和时滞。文中应用该方法辨识了液压位置系统及其噪声模型的阶和参数。仿真和实测阶跃响应比较,证明得到的辨识模型是有效的。 相似文献
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首先研究负荷模型参数对电网仿真频率动态过程影响的程度,确定负荷模型参数辨识灵敏度;随后采用基于粒子群优化算法的故障拟合法进行负荷频率特性参数辨识,这对异步联网系统或孤网系统负荷建模仿真具有重要的实施意义。 相似文献
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本文从“正向”和“逆向”两方面对转子径向摩擦故障的非线性特征进行了分析,首先从机理上对径向摩擦进行了力学描述,分析了其非线性振动的原因,并基于振动波形分析,阐述了其频域特征;然后利用时间序列分析方法讨论了摩擦序列的非线性特性,并用基于条件期望估价的模型结构辨识方法,给出了摩擦故障的最佳时序模型。 相似文献
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受噪声以及复杂传递路径等影响,风电机组齿轮故障特征信号通常比较微弱。为有效诊断齿轮故障,提出一种新的盲解卷积方法——最大重加权峭度盲解卷积方法。重加权峭度对故障信号中单个或少量强冲击干扰具有很好的鲁棒性,且无需待恢复故障冲击序列先验知识。最大重加权峭度盲解卷积方法能有效地解决经典的基于峭度最大化方法倾向于恢复单个主导冲击而非齿轮故障冲击序列的问题,同时相较于常见非全“盲”(依赖故障特征频率先验)方法在工业装备齿轮故障诊断方面具有更强的适用性。仿真信号分析结果表明所提方法在恢复故障冲击序列方面效果显著,在风电机组故障诊断中的应用案例证实了所提方法对齿轮故障诊断的有效性。 相似文献
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本文分析了时间序列建模方法用于处理动态数据,建立系统模型与进行预测控制的特点及问题;研究了时间序列方法建模与系统辨识方法建模以及滤波理论的内在联系;应用系统辨识方法与滤波理论的成果改进了文献[5]采用的参数估计方法,并提出了进一步提高建模速度与预测控制速度的措施。 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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The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci... 相似文献
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针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。 相似文献
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针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。 相似文献
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A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load. 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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针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。 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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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