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动力学 2

多输入多输出 2

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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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Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 173-179 doi: 10.1007/s11709-009-0034-1

摘要： Flutter derivatives are essential for flutter analysis of long-span bridges, and they are generally identified from the vibration testing data of a sectional model suspended in a wind tunnel. Making use of the forced vibration testing data of three sectional models, namely, a thin-plate model, a nearly streamlined model, and a bluff-body model, a comparative study was made to identify the flutter derivatives of each model by using a time-domain method and a frequency-domain method. It was shown that all the flutter derivatives of the thin-plate model identified with the frequency-domain method and time-domain method, respectively, agree very well. Moreover, some of the flutter derivatives of each of the other two models identified with the two methods deviate to some extent. More precisely, the frequency-domain method usually results in smooth curves of the flutter derivatives. The formulation of time-domain method makes the identification results of flutter derivatives relatively sensitive to the signal phase lag between vibration state vector and aerodynamic forces and also prone to be disturbed by noise and nonlinearity.

关键词： long-span bridges     wind-induced vibration     flutter derivatives     forced vibration test     time-domain method     frequency-domain method    

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

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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State identification of home appliance with transient features in residential buildings

《能源前沿（英文）》 2022年 第16卷 第1期   页码 130-143 doi: 10.1007/s11708-022-0822-z

摘要： Nonintrusive load monitoring (NILM) is crucial for extracting patterns of electricity consumption of household appliance that can guide users’ behavior in using electricity while their privacy is respected. This study proposes an online method based on the transient behavior of individual appliances as well as system steady-state characteristics to estimate the operating states of the appliances. It determines the number of states for each appliance using the density-based spatial clustering of applications with noise (DBSCAN) method and models the transition relationship among different states. The states of the working appliances are identified from aggregated power signals using the Kalman filtering method in the factorial hidden Markov model (FHMM). Thereafter, the identified states are confirmed by the verification of system states, which are the combination of the working states of individual appliances. The verification step involves comparing the total measured power consumption with the total estimated power consumption. The use of transient features can achieve fast state inference and it is suitable for online load disaggregation. The proposed method was tested on a high-resolution data set such as Labeled hIgh-Frequency daTaset for Electricity Disaggregation (LIFTED) and it outperformed other related methods in the literature.

关键词： nonintrusive load monitoring (NILM)     load disaggregation     online load disaggregation     Kalman filtering     factorial hidden Markov model (FHMM)     Labeled hIgh-Frequency daTaset for Electricity Disaggregation (LIFTED)    

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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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ISO 18186国际标准的制定及思考

包起帆

《中国工程科学》 2012年 第14卷 第10期   页码 23-26

摘要：

随着我国经济的快速发展和技术水平的不断提高，如何提升我国在国际标准化活动中的影响力和话语权的呼声越来越高。国际标准《ISO 18186∶2011 集装箱-RFID货运标签系统》于2011年由国际标准化组织(ISO)正式发布，成为自我国开始参与国际标准化组织活动以来，在物流、物联网领域首个由中国发起、起草和主导的国际标准。这项国际标准是以“构建包括系统平台建设、软硬件设计、商业化运行模式和系统应用的完整产业链”为技术支撑，沿着“技术专利化、专利标准化、标准国际化”的路线，先形成国家标准GB/T 23678—2009，并同步推进相关国际标准的制定。这里将对国际标准制定的过程和方法进行介绍，分享一些经验，以期为我国创新成果上升，为国际标准提供一些有益帮助。

关键词： 国际标准制定     集装箱RFID（无线射频识别）     ISO 18186    

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射频识别在可视化后勤系统中的应用

王爱明,穆晓曦,李艾华

《中国工程科学》 2006年 第8卷 第8期   页码 65-68

摘要：

射频识别技术是一种新型自动识别技术，具有可靠性高、保密性强，方便快捷、非接触等特点。将射频识别技术应用于后勤可视化系统，可以实时获取保障对象的需求及物资供应的类型、数量和流向等信息，从而实现全时段、全方位、全过程的供应保障。介绍了射频识别系统结构及工作原理，同时研究了射频识别技术在后勤可视化系统中的应用，所提出的在运物资可视化系统是根据贴在集装箱和装备上的射频识别标签实现的。

关键词： 可视化后勤     射频识别     在运可视化系统    

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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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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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The research on structural damage identification using rough set and integrated neural network

Juelong LI, Hairui LI, Jianchun XING, Qiliang YANG

《机械工程前沿（英文）》 2013年 第8卷 第3期   页码 305-310 doi: 10.1007/s11465-013-0259-5

摘要：

A huge amount of information and identification accuracy in large civil engineering structural damage identification has not been addressed yet. To efficiently solve this problem, a new damage identification method based on rough set and integrated neural network is first proposed. In brief, rough set was used to reduce attributes so as to decrease spatial dimensions of data and extract effective features. And then the reduced attributes will be put into the sub-neural network. The sub-neural network can give the preliminary diagnosis from different aspects of damage. The decision fusion network will give the final damage identification results. The identification examples show that this method can simplify the redundant information to reduce the neural network model, making full use of the range of information to effectively improve the accuracy of structural damage identification.

关键词： rough set     integrated neural network     damage identification     decision making fusion    

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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）》 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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Calculation of collision frequency function for aerosol particles in free molecule regime in presence

Xiaowei LUO, Yannick BENICHOU, Suyuan YU

《能源前沿（英文）》 2013年 第7卷 第4期   页码 506-510 doi: 10.1007/s11708-013-0275-5

摘要： The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas (free molecule regime). Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.

关键词： aerosol particles     collision frequency function     coagulation    

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Mechanical design, modeling, and identification for a novel antagonistic variable stiffness dexterous

《机械工程前沿（英文）》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0691-5

摘要： This study traces the development of dexterous hand research and proposes a novel antagonistic variable stiffness dexterous finger mechanism to improve the safety of dexterous hand in unpredictable environments, such as unstructured or man-made operational errors through comprehensive consideration of cost, accuracy, manufacturing, and application. Based on the concept of mechanical passive compliance, which is widely implemented in robots for interactions, a finger is dedicated to improving mechanical robustness. The finger mechanism not only achieves passive compliance against physical impacts, but also implements the variable stiffness actuator principle in a compact finger without adding supererogatory actuators. It achieves finger stiffness adjustability according to the biologically inspired stiffness variation principle of discarding some mobilities to adjust stiffness. The mechanical design of the finger and its stiffness adjusting methods are elaborated. The stiffness characteristics of the finger joint and the actuation unit are analyzed. Experimental results of the finger joint stiffness identification and finger impact tests under different finger stiffness presets are provided to verify the validity of the model. Fingers have been experimentally proven to be robust against physical impacts. Moreover, the experimental part verifies that fingers have good power, grasping, and manipulation performance.

关键词： multifingered hand     mechanism design     robot safety     variable stiffness actuator    

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Fuel variability effect on flickering frequency of diffusion flames

Jizhao LI, Yang ZHANG

《能源前沿（英文）》 2009年 第3卷 第2期   页码 134-140 doi: 10.1007/s11708-009-0034-9

摘要： It is known that fuel variability of different gas suppliers may cause combustion instability in a gas turbine combustor. Mechanisms that control the time scale of the heat release oscillations and acoustic pressure perturbations are both physical and chemical in nature, and thus can be influenced by changes in fuel composition. The intent of this study is to investigate the fuel variability on the flickering frequency of diffusion flames in the hope of understanding some of the fundamental aspects of fuel variability effect on the dynamics of combustion. Experiments were conducted at atmospheric pressure with a matrix of methane and propane blends. An optical fibre system was applied to capture simultaneously the flame flickering at two different light frequencies (430 nm and 516 nm), which provided a means of comparing the chemistry change. It was found that the low frequency oscillation of flow and flame structures depended only weakly on the exit velocities of the fuel, while ambient conditions had a significant effect on flickering frequencies and spectrum. The results of using CH and C H as test fuels at different flow rates showed very little variations, with peak frequencies at 11-13 Hz. When the jet flame was not disturbed, harmonics to at least the third mode were obtained in most of these cases. However, the cases which included CH /C H splits of 90/10, 85/15 and 80/20 by volume showed that unstable flickering frequencies and flame harmonics were not observed. When a mixture of methane/propane at a ratio of 1:1 was used the peak flickering frequency was around 6 Hz, and slight disturbance in the environment would cause the harmonics to disappear. Mechanisms thought to produce changes in the dynamic response and frequency harmonics were discussed.

关键词： fuel variability     flickering frequency     diffusion flames     dynamics of combustion    

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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

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

Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

期刊论文

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

Ye GAO, Wei SUN

期刊论文

State identification of home appliance with transient features in residential buildings

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

ISO 18186国际标准的制定及思考

包起帆

期刊论文

射频识别在可视化后勤系统中的应用

王爱明,穆晓曦,李艾华

期刊论文

Variational mode decomposition based modal parameter identification in civil engineering

Mingjie ZHANG, Fuyou XU

期刊论文

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

期刊论文

The research on structural damage identification using rough set and integrated neural network

Juelong LI, Hairui LI, Jianchun XING, Qiliang YANG

期刊论文

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

期刊论文

Calculation of collision frequency function for aerosol particles in free molecule regime in presence

Xiaowei LUO, Yannick BENICHOU, Suyuan YU

期刊论文

Mechanical design, modeling, and identification for a novel antagonistic variable stiffness dexterous

期刊论文

Fuel variability effect on flickering frequency of diffusion flames

Jizhao LI, Yang ZHANG

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