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Improved minimum variance distortionless response spectrum method for efficient and robust non-uniformundersampled frequency identification in blade tip timing

《机械工程前沿（英文）》 2023年 第18卷 第4期 doi: 10.1007/s11465-023-0759-x

摘要： The noncontact blade tip timing (BTT) measurement has been an attractive technology for blade health monitoring (BHM). However, the severe undersampled BTT signal causes a significant challenge for blade vibration parameter identification and fault feature extraction. This study proposes a novel method based on the minimum variance distortionless response (MVDR) of the direction of arrival (DoA) estimation for blade natural frequency estimation from the non-uniformly undersampled BTT signals. First, based on the similarity between the general data acquisition model for BTT and the antenna array model in DoA estimation, the circumferentially arranged probes on the casing can be regarded as a non-uniform linear array. Thus, BTT signal reconstruction is converted into the DoA estimation problem of the non-uniform linear array signal. Second, MVDR is employed to address the severe undersampling issue and recover the BTT undersampled signal. In particular, spatial smoothing is innovatively utilized to enhance the estimation of covariance matrix of the BTT signal to avoid ill-condition or singularity, while improving efficiency and robustness. Lastly, numerical simulation and experimental testing are employed to verify the validity of the proposed method. Monte Carlo simulation results suggest that the proposed method behaves better than conventional methods, especially under a lower signal-to-noise ratio condition. Experimental results indicate that the proposed method can effectively overcome the severe undersampling problem of BTT signal induced by physical limitations, and has a strong potential in the field of BHM.

关键词： blade tip timing (BTT)     frequency identification     minimum variance distortionless response (MVDR)     undersampled     blade health monitoring (BHM)    

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基于频率响应函数的动力学模型修正方法研究

朱凼凼,冯咬齐,向树红

《中国工程科学》 2005年 第7卷 第8期   页码 89-94

摘要：

概述了国内外动力学模型修正技术的研究状况，研究了近些年发展起来的基于频响函数的动力学模型修正方法；利用航天器振动试验测量所得的频响函数，从理论上介绍了频响函数残差法、设计参数型频响函数法和摄动型频响函数法三种基于频响函数的动力学模型修正方法，为动力学模型修正技术的发展提供参考。

关键词： 航天器     动力学     频响函数     模型修正    

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复杂机械结构中高频动响应能量有限元方法研究

祝丹晖,解妙霞,孔祥杰,张文博,陈花玲

《中国工程科学》 2013年 第15卷 第1期   页码 106-112

摘要：

从理论研究和应用研究两个方面追踪了国内外关于能量有限元的发展现状，并指出能量有限元已趋向于预示越来越复杂的结构动响应；接下来介绍本课题组近年来利用能量有限元方法针对实际复杂结构及复杂载荷环境中的高频动响应问题所做的研究工作，主要包括3个部分：一是在考虑多种传递波功率流耦合的情况下，发展了圆柱壳、截锥壳等复杂结构的高频响应能量有限元方法，从而得到了此类结构的中高频局部动响应特性；二是考虑在脉动载荷、混响室等复杂环境中，利用能量有限元方法并结合能量边界元方法预示了结构的高频振动特性和声振耦合特性；三是开发了能量有限元的计算软件，为其大规模应用奠定了基础。最后指出了能量有限元方法目前存在的问题和进一步研究的方向。

关键词： 中高频响应     能量有限元方法     声振响应预示     机械结构     动力学    

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Load shedding scheme for an interconnected hydro-thermal hybrid system with SMES

D. TYAGI, Ashwani KUMAR, Saurabh CHANANA

《能源前沿（英文）》 2012年 第6卷 第3期   页码 227-236 doi: 10.1007/s11708-012-0198-6

摘要： The frequency of the power system varies based on the load pattern of the consumers. With continuous increase in the load, the frequency of the system keeps decreasing and may reach its minimum allowable limits. Further increase in the load will result in more frequency drop leading to the need of load shedding, if excess generation is not available to cater the need. This paper proposed a methodology in a hybrid thermal-hydro system for finding the required amount of load to be shed for setting the frequency of the system within its minimum allowable limits. The load shedding steps were obtained based on the rate of change of frequency with the increase in the load in both areas. The impact of superconducting magnetic energy storage (SMES) was obtained on load shedding scheme. The comparison of the results was presented on the two-area system.

关键词： critical load     frequency response     load shedding     multi-area system     rate of change of frequency     superconducting magnetic energy storage (SMES) device    

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Load shedding scheme for the two-area system with linear quadratic regulator

D. TYAGI, Ashwani KUMAR, Saurabh CHANANA

《能源前沿（英文）》 2013年 第7卷 第1期   页码 90-102 doi: 10.1007/s11708-012-0224-8

摘要： The power system is prone to many emergency conditions which may lead to emergency state of operation with decay in the system frequency. The dramatic change in the frequency can result in cascaded failure of the system. In order to avoid power system collapse, load shedding (LS) schemes are adopted with the optimal amount of load shed. This paper proposed a methodology in a two-area thermal-thermal system for finding the required amount of load to be shed for setting the frequency of the system within minimum allowable limits. The LS steps have been obtained based on the rate of change of frequency with the increase in load in steps. A systematic study has been conducted for three scenarios: the scheme with a conventional integral controller; the scheme with a linear quadratic regulator (LQR); and the scheme with an LQR and superconducting magnetic energy storage devices (SMES). A comparison of the results has been presented on the two-area system.

关键词： critical load     frequency response     load shedding (LS)     multi-area system     rate of change of frequency     linear quadratic regulator (LQR)     superconducting magnetic energy storage devices (SMES)    

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Inverse identification of the mechanical parameters of a pipeline hoop and analysis of the effect of preload

Ye GAO, Wei SUN

《机械工程前沿（英文）》 2019年 第14卷 第3期   页码 358-368 doi: 10.1007/s11465-019-0539-9

摘要： To create a dynamic model of a pipeline system effectively and analyze its vibration characteristics, the mechanical characteristic parameters of the pipeline hoop, such as support stiffness and damping under dynamic load, must be obtained. In this study, an inverse method was developed by utilizing measured vibration data to identify the support stiffness and damping of a hoop. The procedure of identifying such parameters was described based on the measured natural frequencies and amplitudes of the frequency response functions (FRFs) of a pipeline system supported by two hoops. A dynamic model of the pipe-hoop system was built with the finite element method, and the formulas for solving the FRF of the pipeline system were provided. On the premise of selecting initial values reasonably, an inverse identification algorithm based on sensitivity analysis was proposed. A case study was performed, and the mechanical parameters of the hoop were identified using the proposed method. After introducing the identified values into the analysis model, the reliability of the identification results was validated by comparing the predicted and measured FRFs of the pipeline. Then, the developed method was used to identify the support stiffness and damping of the pipeline hoop under different preloads of the bolts. The influence of preload was also discussed. Results indicated that the support stiffness and damping of the hoop exhibited frequency-dependent characteristics. When the preloads of the bolts increased, the support stiffness increased, whereas the support damping decreased.

关键词： inverse identification     pipeline hoop     frequency response function     mechanical parameters     preload    

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Soil seismic analysis for 2D oblique incident waves using exact free-field responses by frequency-based

《结构与土木工程前沿（英文）》 2022年 第16卷 第12期   页码 1530-1551 doi: 10.1007/s11709-022-0900-7

摘要： The seismic analysis of a viscoelastic half-space under two-dimensional (2D) oblique incident waves is carried out by the finite/infinite element method (FIEM). First, the frequency-domain exact solutions for the displacements and stresses of the free field are derived in general form for arbitrary incident P and SV waves. With the present formulation, no distinction needs to be made for SV waves with over-critical incident angles that make the reflected P waves disappear, while no critical angle exists for P waves. Next, the equivalent seismic forces of the earthquake (Taft Earthquake 1952) imposed on the near-field boundary are generated by combining the solutions for unit ground accelerations with the earthquake spectrum. Based on the asymmetric finite/infinite element model, the frequency-domain motion equations for seismic analysis are presented with the key parameters selected. The results obtained in frequency and time domain are verified against those of Wolf’s, Luco and de Barros’ and for inversely computed ground motions. The parametric study indicated that distinct phase difference exists between the horizontal and vertical responses for SV waves with over-critical incident angles, but not for under-critical incident angles. Other observations were also made for the numerical results inside the text.

关键词： oblique incident waves     critical angle     half-space     finite/infinite element approach     seismic response analysis    

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Identification of dynamic stiffness matrix of bearing joint region

Feng HU, Bo WU, Youmin HU, Tielin SHI

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 289-299 doi: 10.1007/s11465-009-0064-3

摘要： The paper proposes an identification method of the dynamic stiffness matrix of a bearing joint region on the basis of theoretical analysis and experiments. The author deduces an identification model of the dynamic stiffness matrix from the synthetic substructure method. The dynamic stiffness matrix of the bearing joint region can be identified by measuring the matrix of frequency response function (FRFs) of the substructure (axle) and whole structure (assembly of the axle, bearing, and bearing housing) in different positions. Considering difficulty in measuring angular displacement, applying moment, and directly measuring relevant FRFs of rotational degree of freedom, the author employs an accurately calibrated finite element model of the unconstrained structure for indirect estimation. With experiments and simulation analysis, FRFs related with translational degree of freedom, which is estimated through the finite element model, agrees with experimental results, and there is very high reliability in the identified dynamic stiffness matrix of the bearing joint region.

关键词： frequency response function (FRFs)     dynamic stiffness     finite element     synthetic substructure method     joint region    

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Effects of elastic support on the dynamic behaviors of the wind turbine drive train

Shuaishuai WANG, Caichao ZHU, Chaosheng SONG, Huali HAN

《机械工程前沿（英文）》 2017年 第12卷 第3期   页码 348-356 doi: 10.1007/s11465-017-0420-7

摘要：

The reliability and service life of wind turbines are influenced by the complex loading applied on the hub, especially amidst a poor external wind environment. A three-point elastic support, which includes the main bearing and two torque arms, was considered in this study. Based on the flexibilities of the planet carrier and the housing, a coupled dynamic model was developed for a wind turbine drive train. Then, the dynamic behaviors of the drive train for different elastic support parameters were computed and analyzed. Frequency response functions were used to examine how different elastic support parameters influence the dynamic behaviors of the drive train. Results showed that the elastic support parameters considerably influenced the dynamic behaviors of the wind turbine drive train. A large support stiffness of the torque arms decreased the dynamic response of the planet carrier and the main bearing, whereas a large support stiffness of the main bearing decreased the dynamic response of planet carrier while increasing that of the main bearing. The findings of this study provide the foundation for optimizing the elastic support stiffness of the wind turbine drive train.

关键词： wind turbine drive train     elastic support     dynamic behavior     frequency response function    

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Integrated virtual-design methods for forecasting radiated noise of single cylinder diesel block

GUO Lei, HAO Zhiyong, XU Hongmei, LIU Lianyun

《能源前沿（英文）》 2008年 第2卷 第4期   页码 416-421 doi: 10.1007/s11708-008-0097-z

摘要： The two cycle dynamical results, such as the bearing load, the piston thrust, and the load spatial distribution etc., were obtained by hybrid dynamical simulation of the flexible assembly of the block and crank-train. The finite element model of the block was validated by modal test. The frequency response of the block was calculated using the finite element method (FEM). Finally, the radiated noise such as sound power level and efficiency in the out sound field were obtained using the direct boundary element method (BEM).

关键词： bearing     dynamical     frequency response     dynamical simulation     hybrid dynamical    

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Evaluation of transmissibility for a class of nonlinear passive vibration isolators

Z. K. PENG, Z. Q. LANG, G. MENG

《机械工程前沿（英文）》 2012年 第7卷 第4期   页码 401-409 doi: 10.1007/s11465-012-0349-9

摘要：

In this study, the concept of Output Frequency Response Functions (OFRFs) is applied to represent the transmissibility of nonlinear isolators in frequency domain. With the OFRFs estimated from numerical simulation responses, an explicit analytical relationship between the transmissibility and the nonlinear characteristic parameters is derived for a wide class of nonlinear isolators that have nonlinear anti-symmetric damping characteristics and a comprehensive pattern about how the nonlinear damping characteristic parameters might affect the force and displacement transmissibility is built for the vibration isolators. The results reveal that it is reasonable to analyze the force and displacement transmissibility of the nonlinear isolators by simply investigating the fundamental harmonic components of the force and displacement outputs of the nonlinear isolators, and the introduction of a nonlinear anti-symmetric damping into vibration isolators can significantly suppress both the force and displacement transmissibility over the resonant frequency region, but has almost no effect on the transmissibility at non-resonant regions. These conclusions are of significant importance in the analysis and design of the nonlinear vibration isolators with nonlinear anti-symmetric damping.

关键词： nonlinear vibration     volterra series     Output Frequency Response Functions (OFRFs)     nonlinear damping     vibration isolator    

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Analysis of planetary gear transmission in non-stationary operations

Fakher CHAARI, Mohamed Slim ABBES, Fernando Viadero RUEDA, Alfonso Fernandez del RINCON, Mohamed HADDAR

《机械工程前沿（英文）》 2013年 第8卷 第1期   页码 88-94 doi: 10.1007/s11465-013-0361-8

摘要：

Planetary gearboxes operate usually in non-stationary conditions generated mainly by variable loads applied to these transmissions. In order to understand the dynamic behavior of planetary gearboxes in such conditions, a mathematic model is developed including driving unit, transmission and load. The variability of load induces a variable speed of the transmission which is taken into account when characterizing the main dynamic parameter of the transmission which is the mesh stiffness function. This function is not periodic following the variability of the transmission speed. The computation of the dynamic response shows an intimate relation between the vibration amplitude level and the load value. As the load increase the vibration level increase. A combined amplitude and frequency modulation is observed which is well characterized using Short Time Fourier transform more suited than the spectral analysis.

关键词： planetary gearbox     non-stationary conditions     variable load     dynamic response     time frequency analysis    

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Review of recent advances of polymer based dielectrics for high-energy storage in electronic power devices from the perspective of target applications

Wenjie Sun, Jiale Mao, Shuang Wang, Lei Zhang, Yonghong Cheng

《化学科学与工程前沿（英文）》 2021年 第15卷 第1期   页码 18-34 doi: 10.1007/s11705-020-1939-4

摘要： Polymer-based dielectric capacitors are widely-used energy storage devices. However, although the functions of dielectrics in applications like high-voltage direct current transmission projects, distributed energy systems, high-power pulse systems and new energy electric vehicles are similar, their requirements can be quite different. Low electric loss is a critical prerequisite for capacitors for electric grids, while high-temperature stability is an essential pre-requirement for those in electric vehicles. This paper reviews recent advances in this area, and categorizes dielectrics in terms of their foremost properties related to their target applications. Requirements for polymer-based dielectrics in various power electronic equipment are emphasized, including high energy storage density, low dissipation, high working temperature and fast-response time. This paper considers innovations including chemical structure modification, composite fabrication and structure re-design, and the enhancements to material performances achieved. The advantages and limitations of these methods are also discussed.

关键词： dielectric capacitors     polymer-based dielectrics     energy density     dielectric loss     working temperature     frequency response    

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A frequency error estimation for isogeometric analysis of Kirchhoff–Love cylindrical shells

《结构与土木工程前沿（英文）》 2023年 第17卷 第10期   页码 1599-1610 doi: 10.1007/s11709-023-0006-x

摘要： A frequency error estimation is presented for the isogeometric free vibration analysis of Kirchhoff–Love cylindrical shells using both quadratic and cubic basis functions. By analyzing the discrete isogeometric equations with the aid of harmonic wave assumption, the frequency error measures are rationally derived for the quadratic and cubic formulations for Kirchhoff–Love cylindrical shells. In particular, the governing relationship of the continuum frequency for Kirchhoff–Love cylindrical shells is naturally embedded into the frequency error measures without the need of explicit frequency expressions, which usually are not trivial for the shell problems. In accordance with these theoretical findings, the 2nd and 4th orders of frequency accuracy are attained for the isogeometric schemes using quadratic and cubic basis functions, respectively. Numerical results not only thoroughly verify the theoretical convergence rates of frequency solutions, but also manifest an excellent magnitude match between numerical and theoretical frequency errors for the isogeometric free vibration analysis of Kirchhoff–Love cylindrical shells.

关键词： isogeometric analysis     Kirchhoff–Love cylindrical shell     free vibration     frequency error     convergence    

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Capacity limitation of nuclear units in grid based on analysis of frequency regulation

Yiping DAI, Pan JIANG, Lin GAO, Weimin KAN, Xiaoqing XIAO, Ge JIN

《能源前沿（英文）》 2012年 第6卷 第2期   页码 148-154 doi: 10.1007/s11708-012-0174-1

摘要： The increasing capacity of nuclear units in power grid poses threat to system stability and security. Load disturbance may cause overspeed of the units and trigger the overspeed protection controller (OPC). Repeating actions of valves have a strong impact on the security of the equipment and may result in a collapse of the power system. Based on the analysis of frequency regulation, mathematic models for nuclear units in the grid are established in this paper to simulate the dynamic process when load disturbance occurs. The critical action of the OPC is proposed as the constraint of safe operation for the units. The relationship between different styles of frequency regulation and the allowable capacity of the nuclear units in the grid is discussed. This research can help to estimate the capacity limitation of nuclear units in the grid.

关键词： nuclear units capacity     overspeed     primary frequency control (PFC)     second frequency control (SFC)    

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标题 作者 时间 类型 操作

Improved minimum variance distortionless response spectrum method for efficient and robust non-uniformundersampled frequency identification in blade tip timing

期刊论文

基于频率响应函数的动力学模型修正方法研究

朱凼凼,冯咬齐,向树红

期刊论文

复杂机械结构中高频动响应能量有限元方法研究

祝丹晖,解妙霞,孔祥杰,张文博,陈花玲

期刊论文

Load shedding scheme for an interconnected hydro-thermal hybrid system with SMES

D. TYAGI, Ashwani KUMAR, Saurabh CHANANA

期刊论文

Load shedding scheme for the two-area system with linear quadratic regulator

D. TYAGI, Ashwani KUMAR, Saurabh CHANANA

期刊论文

Inverse identification of the mechanical parameters of a pipeline hoop and analysis of the effect of preload

Ye GAO, Wei SUN

期刊论文

Soil seismic analysis for 2D oblique incident waves using exact free-field responses by frequency-based

期刊论文

Identification of dynamic stiffness matrix of bearing joint region

Feng HU, Bo WU, Youmin HU, Tielin SHI

期刊论文

Effects of elastic support on the dynamic behaviors of the wind turbine drive train

Shuaishuai WANG, Caichao ZHU, Chaosheng SONG, Huali HAN

期刊论文

Integrated virtual-design methods for forecasting radiated noise of single cylinder diesel block

GUO Lei, HAO Zhiyong, XU Hongmei, LIU Lianyun

期刊论文

Evaluation of transmissibility for a class of nonlinear passive vibration isolators

Z. K. PENG, Z. Q. LANG, G. MENG

期刊论文

Analysis of planetary gear transmission in non-stationary operations

Fakher CHAARI, Mohamed Slim ABBES, Fernando Viadero RUEDA, Alfonso Fernandez del RINCON, Mohamed HADDAR

期刊论文

Review of recent advances of polymer based dielectrics for high-energy storage in electronic power devices from the perspective of target applications

Wenjie Sun, Jiale Mao, Shuang Wang, Lei Zhang, Yonghong Cheng

期刊论文

A frequency error estimation for isogeometric analysis of Kirchhoff–Love cylindrical shells

期刊论文

Capacity limitation of nuclear units in grid based on analysis of frequency regulation

Yiping DAI, Pan JIANG, Lin GAO, Weimin KAN, Xiaoqing XIAO, Ge JIN

期刊论文