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Simplified equivalent models of large-scale wind power and their application on small-signal stability 被引量:9
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作者 Nan DING Zongxiang LU +1 位作者 Ying QIAO Yong MIN 《Journal of Modern Power Systems and Clean Energy》 SCIE EI 2013年第1期58-64,共7页
With the rapid growth of grid-connected wind power penetration level,it is necessary to study the impacts of wind power on power system stability.The small-signal stability of power systems with large-scale wind power... With the rapid growth of grid-connected wind power penetration level,it is necessary to study the impacts of wind power on power system stability.The small-signal stability of power systems with large-scale wind power is explored using the eigenvalue analysis method.A prototype sample system,the two-synchronous-generator system with a wind farm,is proposed for theoretical analysis.Then,simplified models of wind turbines(WTs)and the corresponding equivalent models of wind farms are analyzed.Three kinds of typical WT models,i.e.,squirrel cage induction generator,doubly-fed induction generator,and permanent magnet synchronous generator are used.Furthermore,based on the simplified equivalent models,effects of large-scale wind farms on the electromechanical oscillation modes(EOMs)of synchronous systems are discussed.Simulation results indicate that wind farms of the three kinds of WTs have positive effects on EOMs.However,long transmission lines connecting wind farmto the systemmay produce negative effects on the small-signal stability of the system. 展开更多
关键词 Wind turbine(WT) Small-signal stability Electromechanical oscillation mode(EOM) Simplified model equivalent model
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Time-varying gravity field model of Sichuan-Yunnan region based on the equivalent mass source model
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作者 Xiaozhen Hou Shi Chen +2 位作者 Linhai Wang Jiancheng Han Dong Ma 《Geodesy and Geodynamics》 EI CSCD 2023年第6期566-572,共7页
High-precision time-varying gravity field is an effective way to study the internal mass movement and understanding the spatio-temporal evolution process of the geodynamic system.Compared to the satellite gravity meas... High-precision time-varying gravity field is an effective way to study the internal mass movement and understanding the spatio-temporal evolution process of the geodynamic system.Compared to the satellite gravity measurement,the repeated terrestrial gravity observation can provide a more high-order signal related to the shallow crust and subsurface.However,the suitable and unified method for gravity model estimation is a key problem for further applications.In this study,we introduce the spherical hexahedron element to simulate the field source mass and forward model the change of gravity field located at the Sichuan-Yunnan region(99—104°E,23—29°N)in the four epochs from 2015 to 2017.Compared to the experimental results based on Slepian or spherical harmonics frequency domain method,this alternative approach is suitable for constructing the equivalent mass source model of regional-scale gravity data,by introducing the first-order smooth prior condition of gravity time-varying signal to suppress the high-frequency component of the signal.The results can provide a higher spatial resolution reference for regional gravity field modeling in the Sichuan-Yunnan region. 展开更多
关键词 Gravity change equivalent source model Time-varying gravity model Gravity field INVERSION
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Research on Equivalent Modeling Method of AC-DC Power Networks Integrating with Renewable Energy Generation
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作者 Weigang Jin Lei Chen +3 位作者 Yifei Li Shencong Zheng Yuqi Jiang Hongkun Chen 《Energy Engineering》 EI 2023年第11期2469-2487,共19页
Along with the increasing integration of renewable energy generation in AC-DC power networks,investigating the dynamic behaviors of this complex system with a proper equivalent model is significant.This paper presents... Along with the increasing integration of renewable energy generation in AC-DC power networks,investigating the dynamic behaviors of this complex system with a proper equivalent model is significant.This paper presents an equivalent modeling method for the AC-DC power networks with doubly-fed induction generator(DFIG)based wind farms to decrease the simulation scale and computational burden.For the AC-DC power networks,the equivalent modeling strategy in accordance with the physical structure simplification is stated.Regarding the DFIG-based wind farms,the equivalent modeling based on the sequential identification of multi-machine parameters using the improved chaotic cuckoo search algorithm(ICCSA)is conducted.In light of the MATLAB simulation platform,a two-zone four-DC interconnected power grid with wind farms is built to check the efficacy of the proposed equivalentmodelingmethod.Fromthe simulation analyses and comparative validation in different algorithms and cases,the proposed method can precisely reflect the steady and dynamic performance of the demonstrated system under N-1 and N-2 fault scenarios,and it can efficiently achieve the parameter identification of the wind farms and fulfill the equivalent modeling.Consequently,the proposed approach’s effectiveness and suitability are confirmed. 展开更多
关键词 equivalent modeling AC-DC power networks renewable energy generation wind farm improved chaotic cuckoo search algorithm
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The initial stages of Li_(2)O_(2) formation during oxygen reduction reaction in Li-O_(2) batteries:The significance of Li_(2)O_(2) in charge-transfer reactions within devices 被引量:1
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作者 Daniela M.Josepetti Bianca P.Sousa +2 位作者 Simone A.J.Rodrigues Renato G.Freitas Gustavo Doubek 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第1期223-231,I0006,共10页
Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion batteries.However,this theoretical characteristic has not yet been converted into a real device wi... Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion batteries.However,this theoretical characteristic has not yet been converted into a real device with high cyclability.Problems with air contamination,metallic lithium reactivity,and complex discharge and charge reactions are the main issues for this technology.A fast and reversible oxygen reduction reaction(ORR)is crucial for good performance of secondary batteries',but the partial knowledge of its mechanisms,especially when devices are concerned,hinders further development.From this perspective,the present work uses operando Raman experiments and electrochemical impedance spectroscopy(EIS)to assess the first stages of the discharge processes in porous carbon electrodes,following their changes cycle by cycle at initial operation.A growth kinetic formation of the discharge product signal(Li_(2)O_(2))was observed with operando Raman,indicating a first-order reaction and enabling an analysis by a microkinetic model.The solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time constants.While the time constant for the anode interface reveals to remain relatively constant after the first discharge,its surface seemed to be more non-uniform.The model indicated that the reaction occurs at the Li_(2)O_(2) surface,decreasing the associated resistance during the initial discharge phase.Furthermore,the growth of Li_(2)O_(2) forms a hetero-phase between Li_(2)O_(2)/electrolyte,while creating a more compact and homogeneous on the Li_(2)O_(2)/cathode surface.The methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis. 展开更多
关键词 Li-O_(2)battery Operando Raman analysis equivalent circuit modeling Time-constant distribution
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Dynamic Response of A Group of Cylindrical Storage Tanks with Baffles Considering the Effect of Soil Foundation
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作者 SUN Ying WANG Jia-dong +3 位作者 HUO Rui-li ZHOU Ding GU Zhen-yuan QIAN Wang-ping 《China Ocean Engineering》 SCIE EI CSCD 2024年第1期129-143,共15页
The sloshing in a group of rigid cylindrical tanks with baffles and on soil foundation under horizontal excitation is studied analytically.The solutions for the velocity potential are derived out by the liquid subdoma... The sloshing in a group of rigid cylindrical tanks with baffles and on soil foundation under horizontal excitation is studied analytically.The solutions for the velocity potential are derived out by the liquid subdomain method.Equivalent models with mass-spring oscillators are established to replace continuous fluid.Combined with the least square technique,Chebyshev polynomials are employed to fit horizontal,rocking and horizontal-rocking coupling impedances of soil,respectively.A lumped parameter model for impedance is presented to describe the effects of soil on tank structures.A mechanical model for the soil-foundation-tank-liquid-baffle system with small amount of calculation and high accuracy is proposed using the substructure technique.The analytical solutions are in comparison with data from reported literature and numerical codes to validate the effectiveness and correctness of the model.Detailed dynamic properties and seismic responses of the soil-tank system are given for the baffle number,size and location as well as soil parameter. 展开更多
关键词 cylindrical tanks multiple annular baffles equivalent analytical model soil−structure interaction subdomain method dynamic response
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A compact X-band backward traveling-wave accelerating structure
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作者 Xian-Cai Lin Hao Zha +4 位作者 Jia-Ru Shi Qiang Gao Fang-Jun Hu Qing-Zhu Li Huai-Bi Chen 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第5期13-29,共17页
Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated tumors.We proposed a compact VHEE facility based on an X-band high-gradient high-power technique.In this study,we invest... Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated tumors.We proposed a compact VHEE facility based on an X-band high-gradient high-power technique.In this study,we investigated and realized the first X-band backward traveling-wave(BTW)accelerating structure as the buncher for a VHEE facility.A method for calculating the parameters of single cell from the field distribution was introduced to simplify the design of the BTW structure.Time-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state.A prototype of the BTW structure with a thermionic cathode-diode electron gun was designed,fabricated,and tested at high power at the Tsinghua X-band high-power test stand.The structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA. 展开更多
关键词 Backward traveling-wave accelerating structure equivalent circuit model High-power test Very high-energy electron radiotherapy
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Full Dynamic Model for Liquid Sloshing Simulation in Cylindrical Tank Shape
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作者 Omar Noui Mohamed Bouazara Marc J. Richard 《World Journal of Mechanics》 2024年第4期55-72,共18页
This study presents a comprehensive full dynamic model designed for simulating liquid sloshing behavior within cylindrical tank structures. The model employs a discretization approach, representing the liquid as a net... This study presents a comprehensive full dynamic model designed for simulating liquid sloshing behavior within cylindrical tank structures. The model employs a discretization approach, representing the liquid as a network of interconnected spring-damper-mass systems. Key aspects include the adaptation of liquid discretization techniques to cylindrical lateral cross-sections and the calculation of stiffness and damping coefficients. External forces, simulating various vehicle maneuvers, are also integrated into the model. The resulting system of equations is solved using Maple Software with the Runge-Kutta-Fehlberg method. This model enables accurate prediction of liquid displacement and pressure forces, offering valuable insights for tank design and fluid dynamics applications. Ongoing refinement aims to broaden its applicability across different liquid types and tank geometries. 展开更多
关键词 Fluid-Structure Interaction equivalent Mechanical Model Liquid Discretization Spring-Mass Model Spring-Mass Network Liquid Simulation
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Minimal Realization of Linear Graph Models for Multi-physics Systems
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作者 Clarence W.DE SILVA 《Instrumentation》 2019年第4期72-84,共13页
An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is termed a multi-domain(or multi-physics)system.Th... An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is termed a multi-domain(or multi-physics)system.The present paper concerns the use of linear graphs(LGs)to generate a minimal model for a multi-physics system.A state-space model has to be a minimal realization.Specifically,the number of state variables in the model should be the minimum number that can completely represent the dynamic state of the system.This choice is not straightforward.Initially,state variables are assigned to all the energy-storage elements of the system.However,some of the energy storage elements may not be independent,and then some of the chosen state variables will be redundant.An approach is presented in the paper,with illustrative examples in the mixed fluid-mechanical domains,to illustrate a way to recognize dependent energy storage elements and thereby obtain a minimal state-space model.System analysis in the frequency domain is known to be more convenient than in the time domain,mainly because the relevant operations are algebraic rather than differential.For achieving this objective,the state space model has to be converted into a transfer function.The direct way is to first convert the state-space model into the input-output differential equation,and then substitute the time derivative by the Laplace variable.This approach is shown in the paper.The same result can be obtained through the transfer function linear graph(TF LG)of the system.In a multi-physics system,first the physical domains have to be converted into an equivalent single domain(preferably,the output domain of the system),when using the method of TFLG.This procedure is illustrated as well,in the present paper. 展开更多
关键词 Multi-physics Modelling Mechatronic Systems Linear Graphs Dependent Energy Storage Elements Redundant State Variables Minimal State-space Realization Domain Conversion equivalent models Frequency-domain Model
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Mass‑Spring‑Damping Theory Based Equivalent Mechanical Model for Cylindrical Lithium‑ion Batteries under Mechanical Abuse 被引量:3
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作者 Wenwei Wang Yiding Li +1 位作者 Cheng Lin Sheng Yang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2020年第2期161-174,共14页
An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindri... An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindrical lithium-ion battery consists of a spring-damping parallel unit.Therefore,a spring-damping parallel unit connecting a damping unit in series is selected to construct the constitutive characteristics of the battery under mechanical abuse.Comparison results show that the equivalent mechanical model can more effectively describe the mechanical properties of the batteries than most cubic fitting models,of which the average relative error of the equivalent mechanical model under different states-of-charge is less than 6.75%.Combined with the proposed equivalent mechanical model,the failure process of the batteries was simulated and analyzed using LS-Dyna and HyperWorks.Under rigid rod tests,failure occurred at the core and bottom of the batteries;under hemispherical punch tests,failure occurred at the core and top,consistent with the experimental results.The average prediction error for the failure displacement under different abuse conditions is less than 4%in the simulations.The equivalent mechanical model requires only a few parameters and can be recognized easily.In the future,the model can be used in safety warning devices based on mechanical penetration. 展开更多
关键词 Cylindrical lithium-ion battery Mass-spring-damping theory equivalent mechanical model Mechanical abuse condition Failure analysis
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EQUIVALENT NORMAL CURVATURE APPROACH MILLING MODEL OF MACHINING FREEFORM SURFACES 被引量:5
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作者 YI Xianzhong MA Weiguo +2 位作者 QIHaiying YAN Zesheng GAO Deli 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2008年第3期52-57,共6页
A new milling methodology with the equivalent normal curvature milling model machining freeform surfaces is proposed based on the normal curvature theorems on differential geometry. Moreover, a specialized whirlwind m... A new milling methodology with the equivalent normal curvature milling model machining freeform surfaces is proposed based on the normal curvature theorems on differential geometry. Moreover, a specialized whirlwind milling tool and a 5-axis CNC horizontal milling machine are introduced. This new milling model can efficiently enlarge the material removal volume at the tip of the whirlwind milling tool and improve the producing capacity. The machining strategy of this model is to regulate the orientation of the whirlwind milling tool relatively to the principal directions of the workpiece surface at the point of contact, so as to create a full match with collision avoidance between the workpiece surface and the symmetric rotational surface of the milling tool. The practical results show that this new milling model is an effective method in machining complex three- dimensional surfaces. This model has a good improvement on finishing machining time and scallop height in machining the freeform surfaces over other milling processes. Some actual examples for manufacturing the freeform surfaces with this new model are given. 展开更多
关键词 equivalent normal curvature milling model Whirlwind milling method Freeform surfaces 5-axis CNC machine Differential geometry
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Multi-layer Quasi Three-dimensional Equivalent Model of Axial-Flux Permanent Magnet Synchronous Machine 被引量:7
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作者 Mingjie He Weiye Li +1 位作者 Jun Peng Jiangtao Yang 《CES Transactions on Electrical Machines and Systems》 CSCD 2021年第1期3-12,共10页
Axial-flux permanent magnet synchronous machine(AFPMSM)enjoys the merits of high torque density and high efficiency,which make it one good candidate in the direct-drive application.The AFPMSM is usually analyzed based... Axial-flux permanent magnet synchronous machine(AFPMSM)enjoys the merits of high torque density and high efficiency,which make it one good candidate in the direct-drive application.The AFPMSM is usually analyzed based on the three-dimensional finite element method(3D FEM)due to its three-dimensional magnetic field distribution.However,the 3D FEM suffers large amount of calculation,time-consuming and is not suitable for the optimization of AFPMSM.Addressing this issue,a multi-layer quasi three-dimensional equivalent model of the AFPMSM is investigated in this paper,which could take the end leakage into consideration.Firstly,the multi-layer quasi three-dimensional equivalent model of the AFPMSM with single stator and single rotor is derived in details,including the equivalent processes and conversions of structure dimensions,motion conditions and electromagnetic parameters.Then,to consider the influence of end leakage on the performance,a correction factor is introduced in the multi-layer quasi three-dimensional equivalent model.Finally,the proposed multi-layer quasi three-dimensional equivalent model is verified by the 3D FEM based on an AFPMSM under different structure parameters.It demonstrates that the errors of flux linkage and average torque obtained by the multi-layer quasi three-dimensional equivalent model and 3D FEM are only around 2%although the structure parameters of the AFPMSM are varied.Besides,the computation time of one case based on the multi-layer quasi three-dimensional equivalent model is only 6 min,which is much less than that of the 3D FEM,1.8 h,under the same conditions.Thus,the proposed multi-layer quasi three-dimensional equivalent model could be used to optimize the AFPMSM and much time could be saved by this method compared with the 3D FEM. 展开更多
关键词 Axial flux equivalent model end leakage permanent magnet machine
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An equivalent model of discharge instability in the discharge chamber of Kaufman ion thruster 被引量:1
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作者 田丰 谢侃 +4 位作者 苗龙 梁福文 宋家辉 白松 王宁飞 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第11期126-134,共9页
The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high... The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high-current stage does not exist.In this study,a complete prediction model for the pulse in the ion thruster is established using the zero-dimensional plasma discharge model and equivalent circuit model.The zero-dimensional plasma discharge model is used to obtain the corresponding plasma parameters by calculating the beam current,discharge current,voltage,and gas flow under actual working conditions.The input parameters of the equivalent circuit model are calculated using empirical formulae to acquire the estimated discharge waveforms.The pulse waveforms obtained using the model are found to be consistent with the experimental results.The model is used to evaluate the process of rapid changes in plasma density.Additionally,this model is employed to predict changes in the pulse waveforms when the volume of the discharge chamber and grid plate transmittance are changed. 展开更多
关键词 Kaufman ion thruster arc discharge pulse phenomenon zero-dimensional plasma discharge model equivalent circuit model
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Simulation study of a magnetocardiogram based on a virtual heart model:effect of a cardiac equivalent source and a volume conductor 被引量:2
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作者 寿国法 夏灵 +2 位作者 马平 唐发宽 戴灵 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第3期121-128,共8页
In this paper, we present a magnetocardiogram (MCG) simulation study using the boundary element method (BEM) and based on the virtual heart model and the realistic human volume conductor model. The different contr... In this paper, we present a magnetocardiogram (MCG) simulation study using the boundary element method (BEM) and based on the virtual heart model and the realistic human volume conductor model. The different contributions of cardiac equivalent source models and volume conductor models to the MCG are deeply and comprehensively investigated. The single dipole source model, the multiple dipoles source model and the equivalent double layer (EDL) source model are analysed and compared with the cardiac equivalent source models. Meanwhile, the effect of the volume conductor model on the MCG combined with these cardiac equivalent sources is investigated. The simulation results demonstrate that the cardiac electrophysiological information will be partly missed when only the single dipole source is taken, while the EDL source is a good option for MCG simulation and the effect of the volume conductor is smallest for the EDL source. Therefore, the EDL source is suitable for the study of MCG forward and inverse problems, and more attention should be paid to it in future MCG studies. 展开更多
关键词 virtual heart model MAGNETOCARDIOGRAM dipole source equivalent double layer source volume conductor model
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Numerical analysis of Shiobara hydropower cavern using practical equivalent approach
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作者 V.B.Maji 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第2期402-410,共9页
Three-dimensional(3 D) numerical simulation of Shiobara hydropower cavern was attempted with the developed practical equivalent approach. This simple equivalent approach integrates the effect of joints and correspondi... Three-dimensional(3 D) numerical simulation of Shiobara hydropower cavern was attempted with the developed practical equivalent approach. This simple equivalent approach integrates the effect of joints and corresponding nonlinearity in the rock and predicts its deformation behaviour. The model requires minimum inputs from field or laboratory tests and is efficient to capture the nonlinear stress-strain responses associated with the jointed rock mass. In this study, the applicability of the model was demonstrated with the 3 D analysis of Shiobara hydropower cavern. The numerical results were also compared with those of six other computational models to analyse the same cavern. The 3 D modelling of powerhouse cavern shows that the present approach, though simple, can be applied to large-scale field problems. The model can precisely predict the deformation values well, and this study confirmed the effectiveness of the approach for simulation of underground structures in jointed rocks. 展开更多
关键词 Jointed rocks equivalent model Shiobara hydropower cavern dimensions(FLAC3D)
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An equivalent circuit model for terahertz quantum cascade lasers:Modeling and experiments
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作者 姚辰 徐天鸿 +2 位作者 万文坚 朱永浩 曹俊诚 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第9期257-260,共4页
Terahertz quantum cascade lasers(THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In... Terahertz quantum cascade lasers(THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In order to illustrate the capability of the model, the steady and dynamic performances of the fabricated THz QCLs are simulated by the model.Compared to the sophisticated numerical methods, the presented model has advantages of fast calculation and good compatibility with circuit simulation for system-level designs and optimizations. The validity of the model is verified by the experimental and numerical results. 展开更多
关键词 TERAHERTZ quantum cascade laser equivalent circuit model five-level rate equations
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Extrinsic equivalent circuit modeling of InP HEMTs based on full-wave electromagnetic simulation
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作者 冯识谕 苏永波 +4 位作者 丁芃 周静涛 彭松昂 丁武昌 金智 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第4期638-646,共9页
With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is pa... With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent.We present an InP HEMT extrinsic parasitic equivalent circuit,in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_(mgd)are taken into account for the high-frequency magnetic field coupling between device electrodes.Based on the suggested parasitic equivalent circuit,through HFSS and advanced design system(ADS)co-simulation,the equivalent circuit parameters are directly extracted in the multi-step system.The HFSS simulation prediction,measurement data,and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit.The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted. 展开更多
关键词 extrinsic equivalent circuit modeling InP HEMT HFSS and ADS co-simulation S-PARAMETERS
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Ferroelectric effect and equivalent polarization charge model of PbZr_(0.2)Ti_(0.8)O_(3)on AlGaN/GaN MIS-HEMT
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作者 赵垚澎 王冲 +6 位作者 郑雪峰 马晓华 李昂 刘凯 何云龙 陆小力 郝跃 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第5期602-606,共5页
PbZr_(0.2)Ti_(0.8)O_(3)(PZT)gate insulator with the thickness of 30 nm is grown by pulsed laser deposition(PLD)in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors(MIS-HEMTs).The ferroelectric... PbZr_(0.2)Ti_(0.8)O_(3)(PZT)gate insulator with the thickness of 30 nm is grown by pulsed laser deposition(PLD)in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors(MIS-HEMTs).The ferroelectric effect of PZT AlGaN/GaN MIS-HEMT is demonstrated.The polarization charge in PZT varies with different gate voltages.The equivalent polarization charge model(EPCM)is proposed for calculating the polarization charge and the concentration of two-dimensional electron gas(2DEG).The threshold voltage(V_(th))and output current density(I_(DS))can also be obtained by the EPCM.The theoretical values are in good agreement with the experimental results and the model can provide a guide for the design of the PZT MIS-HEMT.The polarization charges of PZT can be modulated by different gate-voltage stresses and the V_(th)has a regulation range of 4.0 V.The polarization charge changes after the stress of gate voltage for several seconds.When the gate voltage is stable or changes at high frequency,the output characteristics and the current collapse of the device remain stable. 展开更多
关键词 PZT ALGAN/GAN MIS-HEMT equivalent polarization charge model(EPCM)
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Analysis of Permanent Magnet-assisted Synchronous Reluctance Motor Based on Equivalent Reluctance Network Model
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作者 Changbin Li Xiuhe Wang +3 位作者 Feng Liu Jie Ren Zezhi Xing Xinwei Gu 《CES Transactions on Electrical Machines and Systems》 CSCD 2022年第2期135-144,共10页
In this paper,the equivalent reluctance network model(ERNM)is used to calculate the magnetic circuit of a permanent magnet-assisted synchronous reluctance motor(PMASynRM)and calculate no-load air-gap magnetic field an... In this paper,the equivalent reluctance network model(ERNM)is used to calculate the magnetic circuit of a permanent magnet-assisted synchronous reluctance motor(PMASynRM)and calculate no-load air-gap magnetic field and electromagnetic torque.Iteration method is used to solve the relative permeability of iron core.A novel reluctance network model based on actual distribution of the magnetic flux inside the motor is established.The magnetomotive force(MMF)generated by armature winding affects the relative permeability of iron core,which is considered in the calculation of ERNM to improve the accuracy when the motor is under load.ERNM can be used to measure air-gap flux density,no-load back electromotive force(EMF),the average value of motor torque,the armature winding voltage under load,and power factor.The method of calculating the motor performance is proposed.The results of calculation are consistent with finite element method(FEM)and the computational complexity is much less than that of the FEM.The results of ERNM has been verified,which will provide a simple method for motor design and analysis. 展开更多
关键词 Permanent magnet-assisted synchronous reluctance motor(PMASynRM) equivalent reluctance network model(ERNM) Air-gap flux density No-load back electromotive force(EMF) TORQUE
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Early Debonding Detection of Rebar-Concrete Interface due to External Loading Utilizing AC Impedance Spectroscopy
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作者 WU Lipeng YANG Haitao DONG Xian 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第2期381-386,共6页
A novel method for detecting early damage at the steel-concrete interface due to external loading based on AC impedance spectroscopy technology was proposed.Firstly,alkali pretreatment was introduced to ensure the acc... A novel method for detecting early damage at the steel-concrete interface due to external loading based on AC impedance spectroscopy technology was proposed.Firstly,alkali pretreatment was introduced to ensure the accuracy and repeatability of the AC impedance test.Secondly,the AC impedance spectroscopy between the steel bar and concrete surface of different bonding positions was tested,and then the physical quantities reflecting the bonding damage condition were obtained by equivalent circuit fitting.Theoretical debonding position calculation and AC conductive structure analysis indicate that the change of interface resistance and interface capacitance can seize the development of bonding damage during the loading process.As the interface damage develops,obvious changes in interface resistance and interface capacitance are observed,and they cannot be recovered after unloading. 展开更多
关键词 concrete bond AC impedance spectroscopy equivalent circuit model DAMAGE
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Analysis and Experimental Study on the Friction Force at the Binding Point of Flexible Cable on Satellite
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作者 Ziquan Wang Jinzhu Li +4 位作者 Xuefeng Gao Yunqiang Wu Yingjie Lin Zhiwen Luo Donglei Jiang 《Journal of Beijing Institute of Technology》 EI CAS 2023年第6期754-768,共15页
Mainly for the problem that the friction force generated by the existing process of bind-ing,fixing and fastening the flexible cable on the satellite is unknown,the friction force analysis and experimental research on... Mainly for the problem that the friction force generated by the existing process of bind-ing,fixing and fastening the flexible cable on the satellite is unknown,the friction force analysis and experimental research on the binding point of the flexible cable are carried out.The equivalent model of the cable bundle bound by nylon cable ties is established,the force on the binding point is analyzed,and the empirical formula for calculating the friction force at the binding point is estab-lished.The formula shows that the friction force is related to the cable bundle diameter,the number of winding cycles of silicone rubber tape,the width of nylon cable ties,and the binding force.The friction force tests of the cable diameter of 5.06 mm,8.02 mm,24.02 mm,38.04 mm under different winding turns of tape were carried out,which was compared with the theoretical calculation value.It is concluded that the calculation accuracy of the theoretical model is more than 95%,which can estimate the actual friction force value accurately.This provides a reference and basis for the theoretical and experimental research on the friction force of the flexible cable binding point on satellite. 展开更多
关键词 flexible cable binding point equivalent model friction force experimental study
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