Abstract ：

现有复杂网络应用于故障诊断时,通常基于时域信息出发建模,造成信号频域特征缺失,并且提取的网络拓扑特性过于宏观,对网络内部的局部变化不敏感。相比于宏观特征,局部特征往往蕴含更为丰富的信息,能更准确地表征网络模型。针对此问题,提出一种基于频域复杂网络分解的局部特征提取新方法,该方法借助复杂网络的结构特性来获取信号在频域的变化规律,采用对网络局部变化敏感的微观特性表征整个网络模型,不受机理的限制,应用灵活。采用滚动轴承不同故障的数据进行验证,并与常规复杂网络拓扑特征和时域统计参数进行对比分析,结果表明,本研究方法及提取的特征可分性好,对故障识别正确率达99%,可满足滚动轴承故障诊断的需求,同时对其他...

Keyword ：

故障诊断 频域复杂网络分解 旋转机械 子网络平均度

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Abstract ：

现有复杂网络应用于故障诊断时,通常基于时域信息出发建模,造成信号频域特征缺失,并且提取的网络拓扑特性过于宏观,对网络内部的局部变化不敏感。相比于宏观特征,局部特征往往蕴含更为丰富的信息,能更准确地表征网络模型。针对此问题,提出一种基于频域复杂网络分解的局部特征提取新方法,该方法借助复杂网络的结构特性来获取信号在频域的变化规律,采用对网络局部变化敏感的微观特性表征整个网络模型,不受机理的限制,应用灵活。采用滚动轴承不同故障的数据进行验证,并与常规复杂网络拓扑特征和时域统计参数进行对比分析,结果表明,本研究方法及提取的特征可分性好,对故障识别正确率达99%,可满足滚动轴承故障诊断的需求,同时对其他非平稳信号处理及识别有一定的借鉴意义。

Keyword ：

故障诊断 频域复杂网络分解 旋转机械 子网络平均度

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Abstract ：

针对现有轴心轨迹特征用于转子故障程度判别识别精度低、效果差的问题,提出一种基于轴心轨迹象限信息熵的轴心轨迹特征提取新方法。该方法将轴心轨迹按象限划分为四个区域,分别计算四个区域的信息熵作为故障特征,然后使用模糊聚类进行故障模式识别和故障程度判别。通过分析网格划分程度对于聚类效果的影响,确定了象限信息熵获取过程中关键参数的确定方法,进而通过聚类中心初始化,改善了模糊C均值算法聚类效果不稳定的问题。通过在实验台进行不同故障不同程度的故障模拟实验,将提出的新指标与现有轴心轨迹特征进行对比,结果表明该方法在识别效果和数据可视化方面表现卓著,为后期进行实时状态监测和故障精密诊断提供了新的思路。

Keyword ：

模糊C均值聚类 象限信息熵 轴心轨迹 转子

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差商 铁谱图像 图像分割 油液监测

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Abstract ：

In this paper, a general discussion on the controller design for transient response control is first conducted based on the polynomial method. It is shown for general all-pole close-loop systems, their step responses have zero or nearly zero overshoot under the nominal characteristic ratio assignment [2.5, 2, 2,&mellip;]; while the time constant τ determines the speed of response. The control of the classical benchmark two-mass system is introduced as a case study, in which the m-IPD control configuration is adopted. It is found the time constant τ cannot be arbitrarily specified under the m-IPD control configuration and the nominal characteristic ratio assignment. The designed m-IPD controller demonstrates a sufficient damping performance. Meanwhile, the large and negative derivative gain designed under the nominal characteristic ratio assignment leads to a poor robustness. Through the complementary sensitivity function analysis, the robustness of the polynomial-based m-IPD controller design is found to depend on the term of (K*ds*2+ Ki*ps*+ Ki*); while the characteristic ratio assignment and the time constant determine the nominal time response of the close-loop control system. © 2013 IFAC.

Keyword ：

Characteristic ratio assignments Close-loop control Complementary sensitivity functions Controller designs Damping performance Polynomial methods Speed of response Two mass systems

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Abstract ：

Nonlinear dynamics of cracked rotor system with fractional order damping is investigated with a response-dependent breathing crack model. The fourth order Runge-Kutta method and tenth order continued fraction expansion Euler (CFE-Euler) method are introduced to simulate the proposed system equation of fractional order cracked rotors. The effects of derivative order of damping, rotating speed ratio, crack depth, orientation angle of imbalance relative to the crack direction and mass eccentricity on the system dynamics are demonstrated by bifurcation diagram, Poincare map and rotor trajectory diagram. The results show that the rotor system gets chaotic, quasi-periodic and periodic as the fractional order increases. It is also found that the imbalance eccentricity level, crack depth, rotational speed, fractional damping and crack angle all exert considerable influence on the nonlinear behaviors of cracked rotor system.

Keyword ：

Bifurcation diagram Continued fraction expansion Cracked rotor system Fourth order Runge-Kutta methods Fractional order Nonlinear behavior Orientation angles Trajectory diagram

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Abstract ：

为了有效地提高转子系统特性的分析精度,使其能够准确地进行故障诊断,以Jeffcott转子模型为基础,建立了带有分数阶阻尼和横向呼吸裂纹故障的转子系统的动力学模型.采用4阶龙格库塔法和10阶连分式欧拉法对转子系统的动力学方程进行数值仿真计算,利用轴心轨迹图、Poincare截面映射图和分岔图等,研究了阻尼的分数阶次、转速和裂纹深度对裂纹转子动态特性的影响,并通过实验对理论分析结果进行了验证.分析结果表明:在半临界转速附近,由于裂纹的存在,转子的轴心轨迹呈现明显的双环型(或称内8字形),因此响应中的2倍频分量占主导地位.随着分数次阻尼阶次的增加,转子系统依次经历混沌、准周期和周期运动,同时裂纹深度、不平衡量以及转速对转子系统的动态特性具有明显影响.

Keyword ：

非线性动力学 分数阶阻尼 裂纹转子系统

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Abstract ：

In this paper, an new method is proposed based on support vector regression (SVR) and discrete wavelet decomposition (DWD) for long-term rotor vibration trend forecasting. The feasibility of SVR in long-term vibration trend forecasting is also examined in this paper. And, the discrete wavelet decomposition is used to extract the trend components of vibration time series. Finally, the hybrid prediction model and algorithm of combining SVR and DWD is validated by a group of practical long-term vibration data measured from a flue gas turbine. The results show that the hybrid prediction model possesses more advantageous to forecast long-term state time series than directly using SVR model. © 2009 IEEE.

Keyword ：

Discrete wavelet decomposition Hybrid prediction models Rotor vibrations Support vector regression (SVR) Trend forecasting Trend prediction Vibration data Vibration time

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Abstract ：

In this paper, nonlinear dynamics of Duffing system with fractional order damping is investigated. The four order Runge-Kutta method and ten order CFE-Euler methods are introduced to simulate the fractional order Duffing equations. The effect of taking fractional order on the system dynamics is investigated using phase diagrams, bifurcation diagrams and Poincare map. The bifurcation diagram is also used to exam the effects of excitation amplitude and frequency on Duffing system with fractional order damping. The analysis results show that the fractional order damped Duffing system exhibits period motion, chaos, period motion, chaos, period motion in turn when the fractional order changes from 0.1 to 2.0. A period doubling route to chaos is clearly observed. © 2009 by ASME.

Keyword ：

Bifurcation diagram Duffing equations Duffing system Excitation amplitudes Fractional order Period doubling route to chaos Poincare map System Dynamics

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Abstract ：

Phase shift orbit divides the response space into two different regions one of which can improve or and the other deteriorate the rotor balance. It plays a guiding role in the searching procedure for the balancing correction scheme. Considering the situation that the elliptical shaped orbit of an anisotropic rotor system may lead to a nonlinear phase increment relation between the initial phase vector and unbalance weight, the phase compensation formula then is established to implement the guiding function of the phase shift orbit. The effectiveness and correctness of the phase shift orbit is confirmed in a field balancing of a 300 MW turbine generator set.

Keyword ：

Anisotropic rotor Correction schemes Field balancing Guiding function Holobalancing Initial phase vector Phase compensation Phase shift orbit

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