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Multi-time scale dynamics in power electronics-dominated power systems

Xiaoming YUAN, Jiabing HU, Shijie CHENG

《机械工程前沿（英文）》 2017年第12卷第3期页码 303-311 doi: 10.1007/s11465-017-0428-z

摘要：

Electric power infrastructure has recently undergone a comprehensive transformation from electromagnetics to semiconductors. Such a development is attributed to the rapid growth of power electronic converter applications in the load side to realize energy conservation and on the supply side for renewable generations and power transmissions using high voltage direct current transmission. This transformation has altered the fundamental mechanism of power system dynamics, which demands the establishment of a new theory for power system control and protection. This paper presents thoughts on a theoretical framework for the coming semiconducting power systems.

关键词： power electronics power systems multi-time scale dynamics mass-spring-damping model self-stabilizing and en-stabilizing property multi-time scale power system stabilizer

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Study of an artificial boundary condition based on the damping-solvent extraction method

Qiang XU, Jianyun CHEN, Jing LI, Mingming WANG

《结构与土木工程前沿（英文）》 2012年第6卷第3期页码 281-287 doi: 10.1007/s11709-012-0167-5

摘要： A new artificial boundary condition for time domain analysis of a structure-unlimited-foundation system was proposed. The boundary condition was based on the damping-solvent extraction method. The principle of the damping-solvent extraction method was described. An artificial boundary condition was then established by setting two spring-damper systems and one artificial damping limited region. A test example was developed to verify that the proposed boundary condition and model had high precision. Compared with the damping-solvent extraction method, this boundary condition is easier to be applied to finite element method (FEM)-based numerical calculations.

关键词： damping-solvent extraction method structure-unlimited-foundation system spring-damper system artificial damping limited region finite element method

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Dynamic modeling of hydrostatic guideway considering compressibility and inertia effect

Yikang DU,Kuanmin MAO,Yaming ZHU,Fengyun WANG,Xiaobo MAO,Bin LI

《机械工程前沿（英文）》 2015年第10卷第1期页码 78-88 doi: 10.1007/s11465-015-0331-4

摘要：

Hydrostatic guideways are used as an alternative to contact bearings due to high stiffness and high damping in heavy machine tools. To improve the dynamic characteristic of bearing structure, the dynamic modeling of the hydrostatic guidway should be accurately known. This paper presents a “mass-spring-Maxwell” model considering the effects of inertia, squeeze, compressibility and static bearing. To determine the dynamic model coefficients, numerical simulation of different cases between displacement and dynamic force of oil film are performed with fluent code. Simulation results show that hydrostatic guidway can be taken as a linear system when it is subjected to a small oscillation amplitude. Based on a dynamic model and numerical simulation, every dynamic model’s parameters are calculated by the Levenberg-Marquardt algorithm. Identification results show that “mass-spring-damper” model is the most appropriate dynamic model of the hydrostatic guidway. This paper provides a reference and preparation for the analysis of the dynamic model of the similar hydrostatic bearings.

关键词： hydrostatic guidway dynamic model dynamic mesh technique Levenberg-Marquardt mass-spring-damper model

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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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Analytical study on damping performances of magnetorheological grease damper based on disk squeeze mode

Danxia ZHAO, Changrong LIAO, Qiong LIU, Jing LUO

《机械工程前沿（英文）》 2011年第6卷第3期页码 312-317 doi: 10.1007/s11465-011-0235-x

摘要：

In this paper, a small displacement-type magnetorheological grease (MRG) damper based on disk squeeze mode is proposed. The squeeze flow differential equation is obtained. The Navier slip condition is considered on the surfaces and the boundary compatible condition is established. The radial velocity profiles and the radial pressure distributions are derived respectively, and the mathematical stress expression is calculated. To verify rationality of analytical method, the MRG damper is designed and fabricated according to the technical requirements of an engine vibration isolation system. The experimental damping force from MTS870 Electro-hydraulic Servo with sine wave excitation shows that the proposed analytical method is feasible and provides the reference value for designing MRG damper based on disk squeeze mode.

关键词： magnetorheological grease (MRG) damper squeeze model

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Impact analytical models for earthquake-induced pounding simulation

Kun YE, Li LI

《结构与土木工程前沿（英文）》 2009年第3卷第2期页码 142-147 doi: 10.1007/s11709-009-0029-y

摘要： Structural pounding under earthquake has been recently extensively investigated using various impact analytical models. In this paper, a brief review on the commonly used impact analytical models is conducted. Based on this review, the formula used to determine the damping constant related to the impact spring stiffness, coefficient of restitution, and relative approaching velocity in the Hertz model with nonlinear damping is found to be incorrect. To correct this error, a more accurate approximating formula for the damping constant is theoretically derived and numerically verified. At the same time, a modified Kelvin impact model, which can reasonably account for the physical nature of pounding and conveniently implemented in the earthquake-induced pounding simulation of structural engineering is proposed.

关键词： structural pounding Hertz model Kelvin model nonlinear damping coefficient of restitution

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正交直墙前直立圆柱振荡问题的研究

宁德志,滕斌

《中国工程科学》 2003年第5卷第5期页码 84-91

摘要：

应用镜像原理，将正交直墙前单个圆柱在静水中的振荡问题，转化为4个对称布置圆柱在静水中的振荡问题，由此应用速度势的特征函数展开法，建立了正交直墙前直立圆柱振荡问题的解析解。通过数值计算研究了圆柱与正交直墙间距离大小、水深等因素对附加质量和辐射阻尼的影响。计算结果表明，正交直墙前圆柱上的附加质量和辐射阻尼将明显增大，且随着波数的变化而发生振荡；不同水深中圆柱的附加质量和辐射阻尼在低频区与水深成线性关系。

关键词：附加质量辐射阻尼镜像原理正交直墙圆柱

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Endochronic damage constitutive model for fully-graded aggregate mass concrete

SONG Yupu, WANG Huailiang

《结构与土木工程前沿（英文）》 2007年第1卷第3期页码 274-280 doi: 10.1007/s11709-007-0035-x

摘要： The behavior of deformation and strength of a fully-graded aggregate concrete under complex stress state is the basis of the nonlinear analysis and design for mass concrete structures such as concrete dams. In this paper, based on the combined endochronic theory with damage mechanics and on the quantities of experimental data, an endochronic damage constitutive model suitable for various aggregate grade concrete is proposed. This model takes into consideration the scale effect and the effect of wet screen sieve of aggregate in which the concept of yield surface is not needed and the difference of damage evolution rule of various graded aggregate concrete is a concern. The proposed model is used to analyze the deformation and strength of fully-graded aggregate mass concrete and the wet screened aggregate concrete specimens. The calculated results are in good agreement with experimental data, which can be used as a guide for the design of arch dams and other mass concrete structures.

关键词： concept surface design concern strength

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Vibration suppression of speed-controlled robots with nonlinear control

Paolo BOSCARIOL,Alessandro GASPARETTO

《机械工程前沿（英文）》 2016年第11卷第2期页码 204-212 doi: 10.1007/s11465-016-0380-3

摘要：

In this paper, a simple nonlinear control strategy for the simultaneous position tracking and vibration damping of robots is presented. The control is developed for devices actuated by speed-controlled servo drives. The conditions for the asymptotic stability of the closed-loop system are derived by ensuring its passivity. The capability of achieving improved trajectory tracking and vibration suppression is shown through experimental tests conducted on a three-axis Cartesian robot. The control is aimed to be compatible with most industrial applications given the simplicity of implementation, the reduced computational requirements, and the use of joint position as the only measured signal.

关键词： industrial robot nonlinear control vibration damping model-free control motion control

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Analysis and characterization of wind-solar-constant torque spring hybridized model

Shantanu ACHARYA,Subhadeep BHATTACHARJEE

《能源前沿（英文）》 2014年第8卷第3期页码 279-289 doi: 10.1007/s11708-014-0312-z

摘要： Solar and wind are the most promising renewable energy resources. But their unpredictable and varying nature prevents them from being used as the sole resource for power generation. This paper presents a model of wind and solar thermal hybrid power plant with a spring storage system which is expected to play an efficient role in combating with the drawbacks related to renewable power generation. In the proposed scheme, wind energy is harnessed by a hybrid vertical axis wind turbine, solar energy is utilized by a Stirling engine, and the surplus energy is stored in a winding spring. The paper discusses the working methodologies and analyses the performance of such 2.6 kW hybrid power plant model. It has been observed that the plant is capable of consistently generating 50% of its rated capacity irrespective of limitations in solar and wind resources.

关键词： hybrid vertical axis wind turbine Stirling engine solar-thermal energy wind energy constant torque spring

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Development of rocking constraint device with vertical damping capacity for three-dimensional base-isolated

《结构与土木工程前沿（英文）》 2023年第17卷第3期页码 350-367 doi: 10.1007/s11709-022-0923-0

摘要： A new rocking constraint device (RCD) is developed for three-dimensional (3D) base-isolated frame structures by connecting a custom-designed cylinder pair to provide vertical damping with replaceable damping components installed outside the cylinders when the superstructure undergoes translational motion, and rocking constraint capacity when the superstructure is susceptible to rocking. Theoretical formulas for calculating the damping and rocking constraint stiffness of the RCD are proposed. Two series of sinusoidal loading tests are conducted at different loading frequencies and amplitudes to verify the damping and rocking constraint performance of the RCD. The test results show that the cylinder without orifices on its piston can provide the desired damping with a replaceable damping component, and that the RCD can effectively suppress rocking. Although the vertical stiffness of an individual cylinder is affected by the location of the replaceable damping component and loading frequency, the average vertical stiffness of the two cylinders, which determines the rocking constraint stiffness of the RCD, is independent of the two factors. Comparisons of the test and theoretical results indicate that the errors of the proposed formulas for calculating the damping and rocking constraint stiffness of the RCD do not exceed 12.9% and 11.0%, respectively.

关键词： three-dimensional isolation rocking behavior rocking constraint device replaceable damping component sinusoidal test

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Back to the spring of Wuhan: facts and hope of COVID-19 outbreak

Guangbiao Zhou, Saijuan Chen, Zhu Chen

《医学前沿（英文）》 2020年第14卷第2期页码 113-116 doi: 10.1007/s11684-020-0758-9

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Approximation of structural damping and input excitation force

Mohammad SALAVATI

《结构与土木工程前沿（英文）》 2017年第11卷第2期页码 244-254 doi: 10.1007/s11709-016-0371-9

摘要： Structural dynamic characteristics are the most significant parameters that play a decisive role in structural damage assessment. The more sensitive parameter to the damage is the damping behavior of the structure. The complexity of structural damping mechanisms has made this parameter to be one of the ongoing research topics. Despite all the difficulties in the modeling of damping, there are some approaches like as linear and nonlinear models which are described as the energy dissipation throughout viscous, material or structural hysteretic and frictional damping mechanisms. In the presence of a mathematical model of the damping mechanisms, it is possible to estimate the damping ratio from the theoretical comparison of the damped and un-damped systems. On the other hand, solving the inverse problem of the input force estimation and its distribution to each SDOFs, from the measured structural responses plays an important role in structural identification process. In this paper model-based damping approximation method and a model-less structural input estimation are considered. The effectiveness of proposed methods has been carried out through analytical and numerical simulation of the lumped mass system and the results are compared with reference data. Consequently, high convergence of the comparison results illustrates the satisfactory of proposed approximation methods.

关键词： structural modal parameters damping identification method input excitation force identification Inverse problem

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Static balancing of planar articulated robots

Giuseppe QUAGLIA,Zhe YIN

《机械工程前沿（英文）》 2015年第10卷第4期页码 326-343 doi: 10.1007/s11465-015-0355-9

摘要：

Static balancing for a manipulator’s weight is necessary in terms of energy saving and performance improvement. This paper proposes a method to design balancing devices for articulated robots in industry, based on robotic dynamics. Full design details for the balancing system using springs are presented from two aspects: One is the optimization for the position of the balancing system; the other is the design of the spring parameters. As examples, two feasible balancing devices are proposed, based on different robotic structures: The first solution consists of linkages and springs; the other consists of pulleys, cross mechanisms and (hydro-) pneumatic springs. Then the two solutions are compared. Pneumatic, hydro-pneumatic and mechanical springs are discussed and their parameters are decided according to the requirements of torque compensation. Numerical results show that with the proper design using the methodology presented in this paper, an articulated robot can be statically balanced perfectly in all configurations. This paper therefore provides a design method of the balancing system for other similar structures.

关键词： robotics static balancing pneumatic spring mechanical spring torque compensation

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Effects of green roof damping and configuration on structural seismic response

《结构与土木工程前沿（英文）》页码 1133-1144 doi: 10.1007/s11709-023-0959-9

摘要： Sustainable structures are critical for addressing global climate change. Hence, their structural resilience or ability to recover from natural events must be considered comprehensively. Green roofs are a widely used sustainable feature that improve the environment while providing excellent occupant amenity. To expand their usage, their inherent damping and layout sensitivity to seismic performance are investigated in this study. The soil of a green roof can serve as a damper to dissipate the energy generated by earthquakes or other dynamic events. Results of preliminary analysis show that a green roof soil can increase localized damping by 2.5% under both dry and saturated conditions. Based on these findings, nonlinear time-history analyses are conducted on a three-story building in SAP2000 to monitor the structural behavior with and without a green roof. The increased damping in the green roof soil is beneficial to the structural performance, i.e., it reduces the building displacement and acceleration by 10% and 12%, respectively. Additionally, certain configurations are more effective and beneficial to the structural response than others, which suggests the possibility of design optimization. Based on the findings of this study, new methods of modeling and considering green roofs in structural design are established.

关键词： green infrastructure green roof structural resilience seismic design