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Variational mode decomposition based modal parameter identification in civil engineering

Mingjie ZHANG, Fuyou XU

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1082-1094 doi: 10.1007/s11709-019-0537-3

摘要： An out-put only modal parameter identification method based on variational mode decomposition (VMD) is developed for civil structure identifications. The recently developed VMD technique is utilized to decompose the free decay response (FDR) of a structure into to modal responses. A novel procedure is developed to calculate the instantaneous modal frequencies and instantaneous modal damping ratios. The proposed identification method can straightforwardly extract the mode shape vectors using the modal responses extracted from the FDRs at all available sensors on the structure. A series of numerical and experimental case studies are conducted to demonstrate the efficiency and highlight the superiority of the proposed method in modal parameter identification using both free vibration and ambient vibration data. The results of the present method are compared with those of the empirical mode decomposition-based method, and the superiorities of the present method are verified. The proposed method is proved to be efficient and accurate in modal parameter identification for both linear and nonlinear civil structures, including structures with closely spaced modes, sudden modal parameter variation, and amplitude-dependent modal parameters, etc.

关键词： modal parameter identification     variational mode decomposition     civil structure     nonlinear system     closely spaced modes    

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Experimental study of modal parameter identification in a simulated ambient-excited structure

JI Xiaodong, QIAN Jiaru, XU Longhe

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 281-285 doi: 10.1007/s11709-007-0036-9

摘要： Structure modal parameter online identification was used to monitor the structural health as evidenced by changes in the vibration characteristics. The natural excitation technique and the eigensystem realization algorithm were combined to identify the modal parameters in the time domain of a structure excited by simulated ambient vibrations. The mass-normalized mode shapes were obtained from the eigen-sensitivity analysis. The experimental modal analysis was performed on a two-story steel braced frame model excited by simulated ambient vibrations and hammer impacts. The mass-normalized mode shapes were acquired by changing the structural mass and by eigen-sensitivity analy sis. From finite element analysis results and the experimental data, it is shown that this method is effective.

关键词： eigensystem realization     eigen-sensitivity analysis     realization algorithm     vibration     effective    

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Parameter identification of interconnected power system frequency after trip-out of high voltage transmission

Xuzhan ZHOU,Shanshan LIU,Mingkun WANG,Yiping DAI,Yaohua TANG

《能源前沿（英文）》 2014年 第8卷 第3期   页码 386-393 doi: 10.1007/s11708-014-0323-9

摘要： Accurate modeling and parameters of high voltage (HV) grid are critical for stability research of system frequency. In this paper, simulation modeling of the system frequency was conducted of an interconnected power system with HV transmission lines in China. Based on recorded tripping data of the HV transmission lines, system parameters were identified by using genetic algorithm (GA). The favorable agreement between simulation results and recorded data verifies the validity of gird models and the accuracy of system parameters. The results of this paper can provide reference for the stability research of HV power grid.

关键词： high voltage (HV) grid     frequency stability parameter identification     primary frequency regulation (PFR)    

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Kinematic Model Building and Servo Parameter Identification of 3-HSS Parallel Mechanism

YANG Zhi-yong, WU Jiang, HUANG Tian, NI Yan-bing

《机械工程前沿（英文）》 2006年 第1卷 第1期   页码 60-66 doi: 10.1007/s11465-005-0019-2

摘要：

Aiming at a parallel mechanism with three degrees of freedom, a method for dynamic model building and the parameter identification of its servosystem is presented. First, the reverse solution models of position, velocity, and acceleration of parallelogram branch structure are deduced, and then, its dynamic model of a rigid body is set up by using the virtual work principle. Based on the above model, a method to identify the servo parameter of the parallel mechanism is put up. In this method, the triangle-shaped input with variable frequency is adopted to offset the disadvantages of pseudorandom number sequence in parameter identification, such as dramatically changing the vibration amplitude of the motor, easily impacting the motor that results in its velocity loop to easily open, and so on. Moreover, the rotary inertia can also be identified by the additive mass. The abovementioned data will lay a solid foundation for the optimum performance of the system in the whole workspace.

关键词： building     acceleration     additive     workspace     optimum performance    

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Variable stiffness and damping magnetorheological isolator

Yang ZHOU, Xingyu WANG, Xianzhou ZHANG, Weihua LI

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 310-315 doi: 10.1007/s11465-009-0039-4

摘要： This paper presents the development and characterization of a magnetorheological (MR) fluid-based variable stiffness and damping isolator. The prototype of the MR fluid isolator is fabricated, and its dynamic behavior is measured under various applied magnetic fields. The parameters of the model under various magnetic fields are identified, and the dynamic performance of the isolator is evaluated in simulation. Experimental results indicate that both the stiffness and damping capability of the developed MR isolator can be controlled by an external magnetic field.

关键词： magnetorheological (MR) fluid     stiffness     damping     mathematical model     dynamic performance     parameter identification    

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Kinetic-compartmental modelling of potassium-containing cellulose feedstock gasification

Attila Egedy, Lívia Gyurik, Tamás Varga, Jun Zou, Norbert Miskolczi, Haiping Yang

《化学科学与工程前沿（英文）》 2018年 第12卷 第4期   页码 708-717 doi: 10.1007/s11705-018-1767-y

摘要：

Biomass is of growing interest as a secondary energy source and can be converted to fuels with higher energy density especially by pyrolysis or gasification. Understanding the mechanism and the kinetics of biomass pyrolysis (thermal decomposition) and gasification (conversion of organic material to gases) could be the key to the design of industrial devices capable of processing vast amounts of biomass feedstock. In our work real product components obtained in pyrolysis were took into consideration as well as char and oil as lumped components, and the kinetic constants for a biomass model compound (cellulose) pyrolysis and gasification were identified based on a proposed simplified reaction mechanism within a compartment model structure. A laboratory scale reactor was used for the physical experiments containing consecutive fast pyrolysis and gasification stages using alkali metal (K) containing feedstock, which has a significant effect on the cellulose pyrolysis and gasification. The detailed model was implemented in MATLAB/Simulink environment, and the unknown kinetic parameters were identified based on experimental data. The model was validated based on measurement data, and a good agreement was found. Based on the validated first principle model the optimal parameters were determined as 0.15 mL/min steam flow rate, and 4% K content.

关键词： biomass pyrolysis     kinetic parameter identification     compartment modelling     optimisation    

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基于RBF神经网络的水文地质参数识别

张俊艳,魏连伟,韩文秀,邵景力,崔亚丽,张建立

《中国工程科学》 2004年 第6卷 第8期   页码 74-78

摘要：

水文地质参数识别问题是水文地质学上的一个难题。针对传统水文地质参数识别方法的局限性，提出了水文地质参数识别的径向基函数(RBF )神经网络方法，并通过算例验证了它的可行性与有效性，实现了水文地质参数的自动识别，提高了计算效率，比BP神经网络具有更好的参数识别效果。

关键词： 地下水     水文地质参数     径向基函数(RBF)神经网络     BP神经网络    

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Ambient vibration testing and updating of the finite element model of a simply supported beam bridge

Ivan Gomez ARAUJO, Esperanza MALDONADO, Gustavo Chio CHO

《结构与土木工程前沿（英文）》 2011年 第5卷 第3期   页码 344-354 doi: 10.1007/s11709-011-0124-8

摘要： An ambient vibration test on a concrete bridge constructed in 1971 and calibration of its finite element model are presented. The bridge is characterized by a system of post-tensioned and simply supported beams. The dynamic characteristics of the bridge, i.e. natural frequencies, mode shapes and damping ratios were computed from the ambient vibration tests by using the Eigensystem Realization Algorithm (ERA). Then, these characteristics were used to update the finite element model of the bridge by formulating an optimization problem and then using Genetic Algorithms (GA) to solve it. From the results of the ambient vibration test of this type of bridge, it is concluded that two-dimensional mode shapes exist: in the longitudinal and transverse; and these experimentally obtained dynamic characteristics were also achieved in the analytical model through updating. The application of GAs as optimization techniques showed great versatility to optimize any number and type of variables in the model.

关键词： modal analysis     parameter identification     ambient vibration test     Eigensystem Realization Algorithm (ERA) method     finite element method    

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Processing parameter optimization of fiber laser beam welding using an ensemble of metamodels and MOABC

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0703-5

摘要： In fiber laser beam welding (LBW), the selection of optimal processing parameters is challenging and plays a key role in improving the bead geometry and welding quality. This study proposes a multi-objective optimization framework by combining an ensemble of metamodels (EMs) with the multi-objective artificial bee colony algorithm (MOABC) to identify the optimal welding parameters. An inverse proportional weighting method that considers the leave-one-out prediction error is presented to construct EM, which incorporates the competitive strengths of three metamodels. EM constructs the correlation between processing parameters (laser power, welding speed, and distance defocus) and bead geometries (bead width, depth of penetration, neck width, and neck depth) with average errors of 10.95%, 7.04%, 7.63%, and 8.62%, respectively. On the basis of EM, MOABC is employed to approximate the Pareto front, and verification experiments show that the relative errors are less than 14.67%. Furthermore, the main effect and the interaction effect of processing parameters on bead geometries are studied. Results demonstrate that the proposed EM-MOABC is effective in guiding actual fiber LBW applications.

关键词： laser beam welding     parameter optimization     metamodel     multi-objective    

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Determination of effective stress parameter of unsaturated soils: A Gaussian process regression approach

Pijush Samui, Jagan J

《结构与土木工程前沿（英文）》 2013年 第7卷 第2期   页码 133-136 doi: 10.1007/s11709-013-0202-1

摘要： This article examines the capability of Gaussian process regression (GPR) for prediction of effective stress parameter ( ) of unsaturated soil. GPR method proceeds by parameterising a covariance function, and then infers the parameters given the data set. Input variables of GPR are net confining pressure ( ), saturated volumetric water content ( ), residual water content ( ), bubbling pressure ( ), suction ( ) and fitting parameter ( ). A comparative study has been carried out between the developed GPR and Artificial Neural Network (ANN) models. A sensitivity analysis has been done to determine the effect of each input parameter on . The developed GPR gives the variance of predicted . The results show that the developed GPR is reliable model for prediction of of unsaturated soil.

关键词： unsaturated soil     effective stress parameter     Gaussian process regression (GPR)     artificial neural network (ANN)     variance    

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1000 MW ultra-supercritical turbine steam parameter optimization

FENG Weizhong

《能源前沿（英文）》 2008年 第2卷 第2期   页码 187-193 doi: 10.1007/s11708-008-0030-5

摘要： The 2 × 1000 MW ultra-supercritical steam turbine of Shanghai Waigaoqiao Phase III project, which uses grid frequency regulation and overload control through an overload valve, is manufactured by Shanghai Turbine Company using Siemens technology. Through optimization, the steam pressure is regarded as the criterion between constant pressure and sliding pressure operation. At high circulating water temperature, the turbine overload valve is kept closed when the unit load is lower than 1000 MW while at other circulating water temperatures the turbine can run in sliding pressure operation when the unit load is higher than 1000 MW and the pressure is lower than 27 MPa This increases the unit operation efficiency. The 3D bending technology in the critical piping helps to reduce the project investment and minimize the reheat system pressure drop which improves the unit operation efficiency and safety. By choosing lower circulating water design temperature and by setting the individual Boiler Feedwater Turbine condenser to reduce the exhaust steam flow and the heat load to the main condenser, the unit average back pressure and the terminal temperature difference are minimized. Therefore, the unit heat efficiency is increased.
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Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

《机械工程前沿（英文）》 2020年 第15卷 第1期   页码 55-65 doi: 10.1007/s11465-019-0545-y

摘要： When a fast-steering mirror (FSM) system is designed, satisfying the performance requirements before fabrication and assembly is vital. This study proposes a structural parameter design approach for an FSM system based on the quantitative analysis of the required closed-loop bandwidth. First, the open-loop transfer function of the FSM system is derived. In accordance with the transfer function, the notch filter and proportional-integral (PI) feedback controller are designed as a closed-loop controller. The gains of the PI controller are determined by maximizing the closed-loop bandwidth while ensuring the robustness of the system. Then, the two unknown variables of rotational radius and stiffness in the open-loop transfer function are optimized, considering the bandwidth as a constraint condition. Finally, the structural parameters of the stage are determined on the basis of the optimized results of rotational radius and stiffness. Simulations are conducted to verify the theoretical analysis. A prototype of the FSM system is fabricated, and corresponding experimental tests are conducted. Experimental results indicate that the bandwidth of the proposed FSM system is 117.6 Hz, which satisfies the minimum bandwidth requirement of 100 Hz.

关键词： fast-steering mirror     structural parameter     PI controller     bandwidth     notch filter    

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Energy efficient cutting parameter optimization

Xingzheng CHEN, Congbo LI, Ying TANG, Li LI, Hongcheng LI

《机械工程前沿（英文）》 2021年 第16卷 第2期   页码 221-248 doi: 10.1007/s11465-020-0627-x

摘要： Mechanical manufacturing industry consumes substantial energy with low energy efficiency. Increasing pressures from energy price and environmental directive force mechanical manufacturing industries to implement energy efficient technologies for reducing energy consumption and improving energy efficiency of their machining processes. In a practical machining process, cutting parameters are vital variables set by manufacturers in accordance with machining requirements of workpiece and machining condition. Proper selection of cutting parameters with energy consideration can effectively reduce energy consumption and improve energy efficiency of the machining process. Over the past 10 years, many researchers have been engaged in energy efficient cutting parameter optimization, and a large amount of literature have been published. This paper conducts a comprehensive literature review of current studies on energy efficient cutting parameter optimization to fully understand the recent advances in this research area. The energy consumption characteristics of machining process are analyzed by decomposing total energy consumption into electrical energy consumption of machine tool and embodied energy of cutting tool and cutting fluid. Current studies on energy efficient cutting parameter optimization by using experimental design method and energy models are reviewed in a comprehensive manner. Combined with the current status, future research directions of energy efficient cutting parameter optimization are presented.

关键词： energy efficiency     cutting parameter     optimization     machining process    

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Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

Xueping PAN, Ping JU, Feng WU, Yuqing JIN

《机械工程前沿（英文）》 2017年 第12卷 第3期   页码 367-376 doi: 10.1007/s11465-017-0429-y

摘要：

A new hierarchical parameter estimation method for doubly fed induction generator (DFIG) and drive train system in a wind turbine generator (WTG) is proposed in this paper. Firstly, the parameters of the DFIG and the drive train are estimated locally under different types of disturbances. Secondly, a coordination estimation method is further applied to identify the parameters of the DFIG and the drive train simultaneously with the purpose of attaining the global optimal estimation results. The main benefit of the proposed scheme is the improved estimation accuracy. Estimation results confirm the applicability of the proposed estimation technique.

关键词： wind turbine generator     DFIG     drive train system     hierarchical parameter estimation method     trajectory sensitivity technique    

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Non-convex sparse optimization-based impact force identification with limited vibration measurements

《机械工程前沿（英文）》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0762-2

摘要： Impact force identification is important for structure health monitoring especially in applications involving composite structures. Different from the traditional direct measurement method, the impact force identification technique is more cost effective and feasible because it only requires a few sensors to capture the system response and infer the information about the applied forces. This technique enables the acquisition of impact locations and time histories of forces, aiding in the rapid assessment of potentially damaged areas and the extent of the damage. As a typical inverse problem, impact force reconstruction and localization is a challenging task, which has led to the development of numerous methods aimed at obtaining stable solutions. The classical ℓ2 regularization method often struggles to generate sparse solutions. When solving the under-determined problem, ℓ2 regularization often identifies false forces in non-loaded regions, interfering with the accurate identification of the true impact locations. The popular ℓ1 sparse regularization, while promoting sparsity, underestimates the amplitude of impact forces, resulting in biased estimations. To alleviate such limitations, a novel non-convex sparse regularization method that uses the non-convex ℓ1−2 penalty, which is the difference of the ℓ1 and ℓ2 norms, as a regularizer, is proposed in this paper. The principle of alternating direction method of multipliers (ADMM) is introduced to tackle the non-convex model by facilitating the decomposition of the complex original problem into easily solvable subproblems. The proposed method named ℓ1−2-ADMM is applied to solve the impact force identification problem with unknown force locations, which can realize simultaneous impact localization and time history reconstruction with an under-determined, sparse sensor configuration. Simulations and experiments are performed on a composite plate to verify the identification accuracy and robustness with respect to the noise of the ℓ1−2-ADMM method. Results indicate that compared with other existing regularization methods, the ℓ1−2-ADMM method can simultaneously reconstruct and localize impact forces more accurately, facilitating sparser solutions, and yielding more accurate results.

关键词： impact force identification     inverse problem     sparse regularization     under-determined condition     alternating direction method of multipliers    

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标题 作者 时间 类型 操作

Variational mode decomposition based modal parameter identification in civil engineering

Mingjie ZHANG, Fuyou XU

期刊论文

Experimental study of modal parameter identification in a simulated ambient-excited structure

JI Xiaodong, QIAN Jiaru, XU Longhe

期刊论文

Parameter identification of interconnected power system frequency after trip-out of high voltage transmission

Xuzhan ZHOU,Shanshan LIU,Mingkun WANG,Yiping DAI,Yaohua TANG

期刊论文

Kinematic Model Building and Servo Parameter Identification of 3-HSS Parallel Mechanism

YANG Zhi-yong, WU Jiang, HUANG Tian, NI Yan-bing

期刊论文

Variable stiffness and damping magnetorheological isolator

Yang ZHOU, Xingyu WANG, Xianzhou ZHANG, Weihua LI

期刊论文

Kinetic-compartmental modelling of potassium-containing cellulose feedstock gasification

Attila Egedy, Lívia Gyurik, Tamás Varga, Jun Zou, Norbert Miskolczi, Haiping Yang

期刊论文

基于RBF神经网络的水文地质参数识别

张俊艳,魏连伟,韩文秀,邵景力,崔亚丽,张建立

期刊论文

Ambient vibration testing and updating of the finite element model of a simply supported beam bridge

Ivan Gomez ARAUJO, Esperanza MALDONADO, Gustavo Chio CHO

期刊论文

Processing parameter optimization of fiber laser beam welding using an ensemble of metamodels and MOABC

期刊论文

Determination of effective stress parameter of unsaturated soils: A Gaussian process regression approach

Pijush Samui, Jagan J

期刊论文

1000 MW ultra-supercritical turbine steam parameter optimization

FENG Weizhong

期刊论文

Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

期刊论文

Energy efficient cutting parameter optimization

Xingzheng CHEN, Congbo LI, Ying TANG, Li LI, Hongcheng LI

期刊论文

Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

Xueping PAN, Ping JU, Feng WU, Yuqing JIN

期刊论文

Non-convex sparse optimization-based impact force identification with limited vibration measurements

期刊论文