In this paper,we propose an RLC equivalent circuit model theory which can accurately predict the spectral response and resonance characteristics of metamaterial absorption structures,extend its design,and characterize...In this paper,we propose an RLC equivalent circuit model theory which can accurately predict the spectral response and resonance characteristics of metamaterial absorption structures,extend its design,and characterize the parameters of the model in detail.By employing this model,we conducted computations to characterize the response wavelength and bandwidth of variously sized metamaterial absorbers.A comparative analysis with Finite Difference Time Domain(FDTD)simulations demonstrated a remarkable level of consistency in the results.The designed absorbers were fabricated using micro-nano fabrication processes,and were experimentally tested to demonstrate absorption rates exceeding 90%at a wavelength of 9.28μm.The predicted results are then compared with test results.The comparison reveals good consistency in two aspects of the resonance responses,thereby confirming the rationality and accuracy of this model.展开更多
One of the core works of analyzing Electrochemical Impedance Spectroscopy(EIS)data is to select an appropriate equivalent circuit model to quantify the parameters of the electrochemical reaction process.However,this p...One of the core works of analyzing Electrochemical Impedance Spectroscopy(EIS)data is to select an appropriate equivalent circuit model to quantify the parameters of the electrochemical reaction process.However,this process often relies on human experience and judgment,which will introduce subjectivity and error.In this paper,an intelligent approach is proposed for matching EIS data to their equivalent circuits based on the Random Forest algorithm.It can automatically select the most suitable equivalent circuit model based on the characteristics and patterns of EIS data.Addressing the typical scenario of metal corrosion,an atmospheric corrosion EIS dataset of low-carbon steel is constructed in this paper,which includes five different corrosion scenarios.This dataset was used to validate and evaluate the pro-posed method in this paper.The contributions of this paper can be summarized in three aspects:(1)This paper proposes a method for selecting equivalent circuit models for EIS data based on the Random Forest algorithm.(2)Using authentic EIS data collected from metal atmospheric corrosion,the paper es-tablishes a dataset encompassing five categories of metal corrosion scenarios.(3)The superiority of the proposed method is validated through the utilization of the established authentic EIS dataset.The ex-periment results demonstrate that,in terms of equivalent circuit matching,this method surpasses other machine learning algorithms in both precision and robustness.Furthermore,it shows strong applicability in the analysis of EIS data.展开更多
Radio frequency capacitively coupled plasmas(RF CCPs)operated in Ar/O_(2)gas mixtures which are widely adopted in microelectronics,display,and photovoltaic industry,are investigated based on an equivalent circuit mode...Radio frequency capacitively coupled plasmas(RF CCPs)operated in Ar/O_(2)gas mixtures which are widely adopted in microelectronics,display,and photovoltaic industry,are investigated based on an equivalent circuit model coupled with a global model.This study focuses on the effects of singlet metastable molecule O_(2)(b^(1)∑_(8)^(+)),highly excited Herzberg states O_(2)(A^(3)∑_(u)^(+),A^(3)△_(u),c^(1)∑_(u)^(-)),and the negative ion O_(2)^(-),which are usually neglected in simulation studies.Specifically,their impact on particle densities,electronegativity,electron temperature,voltage drop across the sheath,and absorbed power in the discharge is analyzed.The results indicate that O_(2)(b^(1)∑_(8)^(+))and O_(2)^(-)exhibit relatively high densities in argon-oxygen discharges.While O_(2)(A^(3)∑_(u)^(+),A^(3)△_(u),c^(1)∑_(u)^(-))play a critical role in O_(2)b1S+g production,especially at higher pressure.The inclusion of these particles reduces the electronegativity,electron temperature,and key species densities,especially the O^(-)and O^(*)densities.Moreover,the sheath voltage drop,as well as the inductance and resistance of the plasma bulk are enhanced,while the sheath dissipation power and total absorbed power decrease slightly.With the increasing pressure,the influence of these particles on the discharge properties becomes more significant.The study also explores the generation and loss of main neutral species and charged particles within the pressure range of 20 mTorr-100 mTorr(1 Torr=1.33322×10^(2)Pa),offering insights into essential and non-essential reactions for future low-pressure O_(2)and Ar/O_(2)CCP discharge modeling.展开更多
The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little att...The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little attention has been paid to the accuracy of various open circuit voltage(OCV) models for correcting the SoC with aid of the ampere-hour counting method. This paper presents a comprehensive comparison study on eighteen OCV models which cover the majority of models used in literature. The low-current OCV tests are conducted on the typical commercial LiFePO/graphite(LFP) and LiNiMnCoO/graphite(NMC) cells to obtain the experimental OCV-SoC curves at different ambient temperature and aging stages. With selected OCV and SoC points from experimental OCV-SoC curves, the parameters of each OCV model are determined by curve fitting toolbox of MATLAB 2013. Then the fitting OCV-SoC curves based on diversified OCV models are also obtained. The indicator of root-mean-square error(RMSE) between the experimental data and fitted data is selected to evaluate the adaptabilities of these OCV models for their main features, advantages,and limitations. The sensitivities of OCV models to ambient temperatures, aging stages, numbers of data points,and SoC regions are studied for both NMC and LFP cells. Furthermore, the influences of these models on SoC estimation are discussed. Through a comprehensive comparison and analysis on OCV models, some recommendations in selecting OCV models for both NMC and LFP cells are given.展开更多
Quickly and accurately obtaining the internal temperature distribution of a transformer plays a key role in predicting its operating conditions and simplifying the maintenance process.A reasonable equivalent thermal c...Quickly and accurately obtaining the internal temperature distribution of a transformer plays a key role in predicting its operating conditions and simplifying the maintenance process.A reasonable equivalent thermal circuit model is a relatively reliable method of obtaining the internal temperature distribution.However,thermal circuit models without targeted consideration of operating conditions and parameter corrections usually limit the accuracy of the results.This paper proposed a five-node transient thermal circuit model with the introduction of nonlinear thermal resistance,which considered the internal structure and winding layout of the core-type high-frequency transformer.The Nusselt number,a crucial variable in heat convection calculations and directly related to the accuracy of thermal resistance parameters,was calibrated on the basis of the distribution of external cooling air.After parameter calibration,the maximum computational error of the hotspot temperature is reduced by 5.48%compared with that of the uncalibrated model.Finally,an experimental platform for temperature monitoring was established to validate the five-node model and its ability to track the temperature change at each reference point after calibrating the Nusselt number.展开更多
A small-signal equivalent circuit model and the ted. The equivalent lumped circuit, which takes the main extraction techniques for photodetector chips are presen- factors that limit a photodetector＇s RF performance i...A small-signal equivalent circuit model and the ted. The equivalent lumped circuit, which takes the main extraction techniques for photodetector chips are presen- factors that limit a photodetector＇s RF performance into consideration,is first determined based on the device＇s physical structure. The photodetector＇s S parameters are then on-wafer measured, and the measured raw data are processed with further calibration. A genetic algorithm is used to fit the measured data, thereby allowing us to calculate each parameter value of the model. Experimental resuits show that the modeled parameters are well matched to the measurements in a frequency range from 130MHz to 20GHz, and the proposed method is proved feasible. This model can give an exact description of the photodetector chip＇s high frequency performance,which enables an effective circuit-level prediction for photodetector and optoelectronic integrated circuits.展开更多
All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid...All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs,which is challenging to investigate quantitatively by experimental approach.This work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in ASSLBs.With the assistance of an equivalent circuit model and distribution of relaxation times,it is discovered that as the number of voids and the sharpness of cracks increase,the contact resistance Rcgrows and ultimately dominates the battery impedance.Through accurate fitting,inverse proportional relations between contact resistance Rcand(1-porosity)as well as crack angle was disclosed.This contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs.展开更多
Small signal equivalent circuit model and modulation properties of vertical cavity surface emitting lasers(VCSEL's) are presented.The modulation properties both in analytic equation calculation and in circuit mo...Small signal equivalent circuit model and modulation properties of vertical cavity surface emitting lasers(VCSEL's) are presented.The modulation properties both in analytic equation calculation and in circuit model simulation are studied.The analytic equation calculation of the modulation properties is calculated by using Mathcad program and the circuit model simulation is simulated by using Pspice program respectively.The results of calculation and the simulation are in good agreement with each other.Experiment is performed to testify the circuit model.展开更多
The development of magnesium batteries strongly relies on the use of a Mg metal anode and its benefits of high volumetric capacity,reduction potential,low cost and improved safety,however,to date,it still lacks suffic...The development of magnesium batteries strongly relies on the use of a Mg metal anode and its benefits of high volumetric capacity,reduction potential,low cost and improved safety,however,to date,it still lacks sufficient cycling stability and reversibility.Along with the electrolyte selection,the interfacial processes can be affected by the anode itself applying electrode engineering strategies.In this study,six different Mg anode approaches–namely bare Mg metal,Mg foil with an organic and inorganic artificial solid electrolyte interphase,Mg alloy,Mg pellet and a tape-casted Mg slurry–are selected to be investigated by means of electrochemical impedance spectroscopy in Mg|Mg and Mg|S cells.While a plating/stripping overpotential asymmetry was observed and assigned to the desolvation during Mg plating,the impedance spectra of stripping and plating hardly differ for all applied anodes.In contrast,the sulfur species significantly influence the impedance response by altering the surface layer composition.By systematic process assignment of the gained spectra in Mg|Mg and Mg|S cells,specific equivalent circuit models for different anodes and cell conditions are derived.Overall,the study aims to give valuable insights into the interfacial processes of Mg anodes to support their further development toward long-lasting Mg batteries.展开更多
Quantum well infrared photodetectors(QWIPs) based on intersubband transitions hold significant potential for high bandwidth operation. In this work, we establish a carrier transport optimization model incorporating el...Quantum well infrared photodetectors(QWIPs) based on intersubband transitions hold significant potential for high bandwidth operation. In this work, we establish a carrier transport optimization model incorporating electron injection at the emitter to investigate the carrier dynamics time and impedance spectroscopy in GaAs/AlGaAs QWIPs. Our findings provide novel evidence that the escape time of electrons is the key limiting factor for the 3-dB bandwidth of QWIPs. Moreover, to characterize the impact of carrier dynamics time and non-equilibrium space charge region on impedance, we developed an equivalent circuit model where depletion region resistance and capacitance are employed to describe non-equilibrium space charge region. Using this model, we discovered that under illumination, both net charge accumulation caused by variations in carrier dynamics times within quantum wells and changes in width of non-equilibrium space charge region exert different dominant influences on depletion region capacitance at various doping concentrations.展开更多
With the rise of the electric vehicle industry,as the power source of electric vehicles,lithium battery has become a research hotspot.The state of charge(SOC)estimation and modelling of lithium battery are studied in ...With the rise of the electric vehicle industry,as the power source of electric vehicles,lithium battery has become a research hotspot.The state of charge(SOC)estimation and modelling of lithium battery are studied in this paper.The ampere-hour(Ah)integration method based on external characteristics is analyzed,and the open-circuit voltage(OCV)method is studied.The two methods are combined to estimate SOC.Considering the accuracy and complexity of the model,the second-order RC equivalent circuit model of lithium battery is selected.Pulse discharge and exponential fitting of lithium battery are used to obtain corresponding parameters.The simulation is carried out by using fixed resistance capacitance and variable resistance capacitor respectively.The accuracy of variable resistance and capacitance model is 2.9%,which verifies the validity of the proposed model.展开更多
Intra-body communication (IBC) is a new,emerging,short-range and human body based communication methodology.It is a technique to network various devices on human body,by utilizing the conducting properties of human ti...Intra-body communication (IBC) is a new,emerging,short-range and human body based communication methodology.It is a technique to network various devices on human body,by utilizing the conducting properties of human tissues,suitable for currently fast developing Body area network (BAN)/Body sensor network (BSN).IBC is believed to have advantages in power consumption,electromagnetic radiation,interference from external electromagnetic noise,security,and restriction in spectrum resource.In this article,the authors develop two models,which are analytical and empirical approaches,for comparing the performance and accuracy of IBC on a human limb.Through in vivo experiment of five volunteers,both models basically match with the experimental result with equivalent circuit model superior than electromagnetic model in term of maximum error.展开更多
Compact torus(CT)injection is one of the most promising methods for the central fuelling of next-generation reactor-grade fusion devices due to its high density,high velocity,and selfcontained magnetised structure.A n...Compact torus(CT)injection is one of the most promising methods for the central fuelling of next-generation reactor-grade fusion devices due to its high density,high velocity,and selfcontained magnetised structure.A newly compact torus injector(CTI)device in Keda Torus e Xperiment(KTX),named KTX-CTI,was successfully developed and tested at the University of Science and Technology in China.In this study,first,we briefly introduce the basic principles and structure of KTX-CTI,and then,present an accurate circuit model that relies on nonlinear regression analysis(NRA)for studying the current waveform of the formation region.The current waveform,displacement,and velocity of CT plasma in the acceleration region are calculated using this NRA-based one-dimensional point model.The model results were in good agreement with the experiments.The next-step upgrading reference scheme of the KTX-CTI device is preliminarily investigated using this NRA-based point model.This research can provide insights for the development of experiments and future upgrades of the device.展开更多
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
The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission d...The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission delay of photogenerated carriers is given.From analysis on the frequency domain of the circuit model the device has two poles.One has the relationship with junction capacitance and the DPD’s load,the other with the depth and the doping concentration of the N-well in the DPD.Different depth of the N-well and different area of the DPDs with bandwidth were compared.The analysis results are important to design the high speed DPDs.展开更多
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
In the parametric modeling of the circuit model for glow discharge in air,a new method for the design of glow discharge circuit model is presented.The new circuit model is an important reference for the design of plas...In the parametric modeling of the circuit model for glow discharge in air,a new method for the design of glow discharge circuit model is presented.The new circuit model is an important reference for the design of plasma power supply,the simulation of glow discharge plasma actuator and the simulation of glow discharge plasma anemometer.The modeling approach consists in developing an electrical model of the glow discharge in air based on circuit components.The structure of the circuit model is established according to the theoretical analysis and the experimental device.Then the parameters of the circuit model are obtained based on the circuit analysis.Finally,the circuit model is verified by comparing the simulation current with the experimental current.This model takes into account the whole framework of the air glow discharge including the sheath and the plasma area.The built circuit model is feasible and reliable,thus being instructive for the investigation of the glow discharge in air.展开更多
We introduce the paradigm of chaotic mathematical circuitry which shows some similarity to the paradigm of electronic circuitry, especially in the frame of chaotic attractors for solving practical problems(generating ...We introduce the paradigm of chaotic mathematical circuitry which shows some similarity to the paradigm of electronic circuitry, especially in the frame of chaotic attractors for solving practical problems(generating hyperchaos; developing chaos based pseudo random number generator(CPRNG) and chaotic multistream PRNG; secure communication via synchronization). They can also be used in cryptography, generic algorithms in optimization, control, etc.展开更多
An analytical model for current-voltage behavior of amorphous In-Ga-Zn-O thin-film transistors（a-IGZO TFTs）with dual-gate structures is developed.The unified expressions for synchronous and asynchronous operating mo...An analytical model for current-voltage behavior of amorphous In-Ga-Zn-O thin-film transistors（a-IGZO TFTs）with dual-gate structures is developed.The unified expressions for synchronous and asynchronous operating modes are derived on the basis of channel charges,which are controlled by gate voltage.It is proven that the threshold voltage of asynchronous dual-gate IGZO TFTs is adjusted in proportion to the ratio of top insulating capacitance to the bottom insulating capacitance（C_（TI）/C_（BI））.Incorporating the proposed model with Verilog-A,a touch-sensing circuit using dual-gate structure is investigated by SPICE simulations.Comparison shows that the touch sensitivity is increased by the dual-gate IGZO TFT structure.展开更多
The V-shaped electro-optical properties control is investigated by an equivalent circuit model.Simu-lation results show that genuine V-shaped form is only observed at hysteresis inversion frequency,and be-low and abov...The V-shaped electro-optical properties control is investigated by an equivalent circuit model.Simu-lation results show that genuine V-shaped form is only observed at hysteresis inversion frequency,and be-low and above this frequency an anomalous and normal hysteresis are observed.And the inversion fre-quency decreases with the resistance of ferroelectric liquid crystal(FLC)layer following logf_i=-alogR_(LC)+b .The results are in good accordance with the reported experimental results.展开更多
基金Supported by the National Natural Science Foundation of China(62174092)the Open Fund of State Key Laboratory of Infrared Physics(SITP-NLIST-ZD-2023-04)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0580000)。
文摘In this paper,we propose an RLC equivalent circuit model theory which can accurately predict the spectral response and resonance characteristics of metamaterial absorption structures,extend its design,and characterize the parameters of the model in detail.By employing this model,we conducted computations to characterize the response wavelength and bandwidth of variously sized metamaterial absorbers.A comparative analysis with Finite Difference Time Domain(FDTD)simulations demonstrated a remarkable level of consistency in the results.The designed absorbers were fabricated using micro-nano fabrication processes,and were experimentally tested to demonstrate absorption rates exceeding 90%at a wavelength of 9.28μm.The predicted results are then compared with test results.The comparison reveals good consistency in two aspects of the resonance responses,thereby confirming the rationality and accuracy of this model.
基金support of the project from the National Key R&D Program of China,Research and Application of Sensing System for Cross-regional Complex Oil&Gas Pipeline Network Safe and Efficiency Operational Status Monitoring(Grant No.2022YFB3207603).
文摘One of the core works of analyzing Electrochemical Impedance Spectroscopy(EIS)data is to select an appropriate equivalent circuit model to quantify the parameters of the electrochemical reaction process.However,this process often relies on human experience and judgment,which will introduce subjectivity and error.In this paper,an intelligent approach is proposed for matching EIS data to their equivalent circuits based on the Random Forest algorithm.It can automatically select the most suitable equivalent circuit model based on the characteristics and patterns of EIS data.Addressing the typical scenario of metal corrosion,an atmospheric corrosion EIS dataset of low-carbon steel is constructed in this paper,which includes five different corrosion scenarios.This dataset was used to validate and evaluate the pro-posed method in this paper.The contributions of this paper can be summarized in three aspects:(1)This paper proposes a method for selecting equivalent circuit models for EIS data based on the Random Forest algorithm.(2)Using authentic EIS data collected from metal atmospheric corrosion,the paper es-tablishes a dataset encompassing five categories of metal corrosion scenarios.(3)The superiority of the proposed method is validated through the utilization of the established authentic EIS dataset.The ex-periment results demonstrate that,in terms of equivalent circuit matching,this method surpasses other machine learning algorithms in both precision and robustness.Furthermore,it shows strong applicability in the analysis of EIS data.
基金supported by the National Natural Science Foundation of China(Grant Nos.12020101005,12475202,12347131,and 12405289).
文摘Radio frequency capacitively coupled plasmas(RF CCPs)operated in Ar/O_(2)gas mixtures which are widely adopted in microelectronics,display,and photovoltaic industry,are investigated based on an equivalent circuit model coupled with a global model.This study focuses on the effects of singlet metastable molecule O_(2)(b^(1)∑_(8)^(+)),highly excited Herzberg states O_(2)(A^(3)∑_(u)^(+),A^(3)△_(u),c^(1)∑_(u)^(-)),and the negative ion O_(2)^(-),which are usually neglected in simulation studies.Specifically,their impact on particle densities,electronegativity,electron temperature,voltage drop across the sheath,and absorbed power in the discharge is analyzed.The results indicate that O_(2)(b^(1)∑_(8)^(+))and O_(2)^(-)exhibit relatively high densities in argon-oxygen discharges.While O_(2)(A^(3)∑_(u)^(+),A^(3)△_(u),c^(1)∑_(u)^(-))play a critical role in O_(2)b1S+g production,especially at higher pressure.The inclusion of these particles reduces the electronegativity,electron temperature,and key species densities,especially the O^(-)and O^(*)densities.Moreover,the sheath voltage drop,as well as the inductance and resistance of the plasma bulk are enhanced,while the sheath dissipation power and total absorbed power decrease slightly.With the increasing pressure,the influence of these particles on the discharge properties becomes more significant.The study also explores the generation and loss of main neutral species and charged particles within the pressure range of 20 mTorr-100 mTorr(1 Torr=1.33322×10^(2)Pa),offering insights into essential and non-essential reactions for future low-pressure O_(2)and Ar/O_(2)CCP discharge modeling.
基金Supported by National Natural Science Foundation of China(Grant No.51507012)Beijing Municipal Natural Science Foundation of China(Grant No.3182035)
文摘The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little attention has been paid to the accuracy of various open circuit voltage(OCV) models for correcting the SoC with aid of the ampere-hour counting method. This paper presents a comprehensive comparison study on eighteen OCV models which cover the majority of models used in literature. The low-current OCV tests are conducted on the typical commercial LiFePO/graphite(LFP) and LiNiMnCoO/graphite(NMC) cells to obtain the experimental OCV-SoC curves at different ambient temperature and aging stages. With selected OCV and SoC points from experimental OCV-SoC curves, the parameters of each OCV model are determined by curve fitting toolbox of MATLAB 2013. Then the fitting OCV-SoC curves based on diversified OCV models are also obtained. The indicator of root-mean-square error(RMSE) between the experimental data and fitted data is selected to evaluate the adaptabilities of these OCV models for their main features, advantages,and limitations. The sensitivities of OCV models to ambient temperatures, aging stages, numbers of data points,and SoC regions are studied for both NMC and LFP cells. Furthermore, the influences of these models on SoC estimation are discussed. Through a comprehensive comparison and analysis on OCV models, some recommendations in selecting OCV models for both NMC and LFP cells are given.
基金supported by the National Natural Science Foundation of China(Grant 52207180)Xi'an High Voltage Apparatus Research Institute Co.Ltd.(Grant K222301-01)the Anhui Provincial Natural Science Foundation(Grant 2208085UD18).
文摘Quickly and accurately obtaining the internal temperature distribution of a transformer plays a key role in predicting its operating conditions and simplifying the maintenance process.A reasonable equivalent thermal circuit model is a relatively reliable method of obtaining the internal temperature distribution.However,thermal circuit models without targeted consideration of operating conditions and parameter corrections usually limit the accuracy of the results.This paper proposed a five-node transient thermal circuit model with the introduction of nonlinear thermal resistance,which considered the internal structure and winding layout of the core-type high-frequency transformer.The Nusselt number,a crucial variable in heat convection calculations and directly related to the accuracy of thermal resistance parameters,was calibrated on the basis of the distribution of external cooling air.After parameter calibration,the maximum computational error of the hotspot temperature is reduced by 5.48%compared with that of the uncalibrated model.Finally,an experimental platform for temperature monitoring was established to validate the five-node model and its ability to track the temperature change at each reference point after calibrating the Nusselt number.
文摘A small-signal equivalent circuit model and the ted. The equivalent lumped circuit, which takes the main extraction techniques for photodetector chips are presen- factors that limit a photodetector＇s RF performance into consideration,is first determined based on the device＇s physical structure. The photodetector＇s S parameters are then on-wafer measured, and the measured raw data are processed with further calibration. A genetic algorithm is used to fit the measured data, thereby allowing us to calculate each parameter value of the model. Experimental resuits show that the modeled parameters are well matched to the measurements in a frequency range from 130MHz to 20GHz, and the proposed method is proved feasible. This model can give an exact description of the photodetector chip＇s high frequency performance,which enables an effective circuit-level prediction for photodetector and optoelectronic integrated circuits.
基金supported by the Beijing Natural Science Foundation(Z200011,L233004)the National Key Research and Development Program(2021YFB2500300)+3 种基金the National Natural Science Foundation of China(52394170,52394171,22109011,22393900,and 22108151)the Tsinghua-Jiangyin Innovation Special Fund(TJISF)(2022JYTH0101)the S&T Program of Hebei(22344402D)the Tsinghua University Initiative Scientific Research Program.
文摘All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs,which is challenging to investigate quantitatively by experimental approach.This work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in ASSLBs.With the assistance of an equivalent circuit model and distribution of relaxation times,it is discovered that as the number of voids and the sharpness of cracks increase,the contact resistance Rcgrows and ultimately dominates the battery impedance.Through accurate fitting,inverse proportional relations between contact resistance Rcand(1-porosity)as well as crack angle was disclosed.This contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs.
文摘Small signal equivalent circuit model and modulation properties of vertical cavity surface emitting lasers(VCSEL's) are presented.The modulation properties both in analytic equation calculation and in circuit model simulation are studied.The analytic equation calculation of the modulation properties is calculated by using Mathcad program and the circuit model simulation is simulated by using Pspice program respectively.The results of calculation and the simulation are in good agreement with each other.Experiment is performed to testify the circuit model.
基金financially supported by the Federal Ministry for Education and Research of Germany(Bundesminis-terium für Bildung und Forschung,BMBF)and the European Commission within the projects“MagSiMal”(03XP0208)“E-MAGIC”(824066),respectively。
文摘The development of magnesium batteries strongly relies on the use of a Mg metal anode and its benefits of high volumetric capacity,reduction potential,low cost and improved safety,however,to date,it still lacks sufficient cycling stability and reversibility.Along with the electrolyte selection,the interfacial processes can be affected by the anode itself applying electrode engineering strategies.In this study,six different Mg anode approaches–namely bare Mg metal,Mg foil with an organic and inorganic artificial solid electrolyte interphase,Mg alloy,Mg pellet and a tape-casted Mg slurry–are selected to be investigated by means of electrochemical impedance spectroscopy in Mg|Mg and Mg|S cells.While a plating/stripping overpotential asymmetry was observed and assigned to the desolvation during Mg plating,the impedance spectra of stripping and plating hardly differ for all applied anodes.In contrast,the sulfur species significantly influence the impedance response by altering the surface layer composition.By systematic process assignment of the gained spectra in Mg|Mg and Mg|S cells,specific equivalent circuit models for different anodes and cell conditions are derived.Overall,the study aims to give valuable insights into the interfacial processes of Mg anodes to support their further development toward long-lasting Mg batteries.
基金financially supported by the National Natural Science Foundation of China (Grant No. 61991442)。
文摘Quantum well infrared photodetectors(QWIPs) based on intersubband transitions hold significant potential for high bandwidth operation. In this work, we establish a carrier transport optimization model incorporating electron injection at the emitter to investigate the carrier dynamics time and impedance spectroscopy in GaAs/AlGaAs QWIPs. Our findings provide novel evidence that the escape time of electrons is the key limiting factor for the 3-dB bandwidth of QWIPs. Moreover, to characterize the impact of carrier dynamics time and non-equilibrium space charge region on impedance, we developed an equivalent circuit model where depletion region resistance and capacitance are employed to describe non-equilibrium space charge region. Using this model, we discovered that under illumination, both net charge accumulation caused by variations in carrier dynamics times within quantum wells and changes in width of non-equilibrium space charge region exert different dominant influences on depletion region capacitance at various doping concentrations.
基金Project(51507073)supported by the National Natural Science Foundation of China。
文摘With the rise of the electric vehicle industry,as the power source of electric vehicles,lithium battery has become a research hotspot.The state of charge(SOC)estimation and modelling of lithium battery are studied in this paper.The ampere-hour(Ah)integration method based on external characteristics is analyzed,and the open-circuit voltage(OCV)method is studied.The two methods are combined to estimate SOC.Considering the accuracy and complexity of the model,the second-order RC equivalent circuit model of lithium battery is selected.Pulse discharge and exponential fitting of lithium battery are used to obtain corresponding parameters.The simulation is carried out by using fixed resistance capacitance and variable resistance capacitor respectively.The accuracy of variable resistance and capacitance model is 2.9%,which verifies the validity of the proposed model.
基金supported by The Science and Technology Development Fund of Macao under grant 014/2007/A1,063/2009/A and 024/2009/A1the Research Committee of the University of Macao under Grants UL012/09-Y1/EEE/VMI01/FST,RG077/09-10S/ VMI/FST,RG075/07-08S/10T/VMI/FST,and RG072/09-10S/ MPU/FSTthe Funds of Fujian Provincial Department of Science & Technology as 2007Y0024,2007T0009,2007I0018 and 2008J1005
文摘Intra-body communication (IBC) is a new,emerging,short-range and human body based communication methodology.It is a technique to network various devices on human body,by utilizing the conducting properties of human tissues,suitable for currently fast developing Body area network (BAN)/Body sensor network (BSN).IBC is believed to have advantages in power consumption,electromagnetic radiation,interference from external electromagnetic noise,security,and restriction in spectrum resource.In this article,the authors develop two models,which are analytical and empirical approaches,for comparing the performance and accuracy of IBC on a human limb.Through in vivo experiment of five volunteers,both models basically match with the experimental result with equivalent circuit model superior than electromagnetic model in term of maximum error.
基金supported by the National Key Research and Development Program of China(Nos.2017YFE0300500,2017YFE0300501)the Institute of Energy,Hefei Comprehensive National Science Center(Nos.19KZS205 and 21KZS202)+3 种基金the International Partnership Program of Chinese Academy of Sciences(No.Y16YZ17271)National Natural Science Foundation of China(Nos.11905143 and 12105088)Users with Excellence Program of Hefei Science Center CAS(No.2020HSC-UE008)The University Synergy Innovation Program of Anhui Province(Nos.GXXT-2021-014,GXXT2021-029)。
文摘Compact torus(CT)injection is one of the most promising methods for the central fuelling of next-generation reactor-grade fusion devices due to its high density,high velocity,and selfcontained magnetised structure.A newly compact torus injector(CTI)device in Keda Torus e Xperiment(KTX),named KTX-CTI,was successfully developed and tested at the University of Science and Technology in China.In this study,first,we briefly introduce the basic principles and structure of KTX-CTI,and then,present an accurate circuit model that relies on nonlinear regression analysis(NRA)for studying the current waveform of the formation region.The current waveform,displacement,and velocity of CT plasma in the acceleration region are calculated using this NRA-based one-dimensional point model.The model results were in good agreement with the experiments.The next-step upgrading reference scheme of the KTX-CTI device is preliminarily investigated using this NRA-based point model.This research can provide insights for the development of experiments and future upgrades of the device.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61434006 and 61704189)the Fund from the Youth Innovation Promotion Association of the Chinese Academy of Sciences。
文摘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.
文摘The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission delay of photogenerated carriers is given.From analysis on the frequency domain of the circuit model the device has two poles.One has the relationship with junction capacitance and the DPD’s load,the other with the depth and the doping concentration of the N-well in the DPD.Different depth of the N-well and different area of the DPDs with bandwidth were compared.The analysis results are important to design the high speed DPDs.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB339803)the National High Technology Research and Development Program of China(Grant No.2011AA010205)+5 种基金the National Natural Science Foundation of China(Grant Nos.61131006,61321492,and 61404149)the Major National Development Project of Scientific Instrument and Equipment,China(Grant No.2011YQ150021)the National Science and Technology Major Project,China(Grant No.2011ZX02707)the Major Project,China(Grant No.YYYJ-1123-1)the International Collaboration and Innovation Program on High Mobility Materials Engineering of the Chinese Academy of Sciencesthe Shanghai Municipal Commission of Science and Technology,China(Grant Nos.14530711300)
文摘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.
基金supported by the Natural Science Foundation of Jiangsu Province (No.BK20140820)the Fundamental Research Funds for the Central Universities (No.NJ20160037)+2 种基金the Natural Science Foundation of China(No.51406083)the Funding of Jiangsu Innovation Program for Graduate Education(No.SJZZ16_0055)the Fundamental Research Funds for the Central Universities
文摘In the parametric modeling of the circuit model for glow discharge in air,a new method for the design of glow discharge circuit model is presented.The new circuit model is an important reference for the design of plasma power supply,the simulation of glow discharge plasma actuator and the simulation of glow discharge plasma anemometer.The modeling approach consists in developing an electrical model of the glow discharge in air based on circuit components.The structure of the circuit model is established according to the theoretical analysis and the experimental device.Then the parameters of the circuit model are obtained based on the circuit analysis.Finally,the circuit model is verified by comparing the simulation current with the experimental current.This model takes into account the whole framework of the air glow discharge including the sheath and the plasma area.The built circuit model is feasible and reliable,thus being instructive for the investigation of the glow discharge in air.
文摘We introduce the paradigm of chaotic mathematical circuitry which shows some similarity to the paradigm of electronic circuitry, especially in the frame of chaotic attractors for solving practical problems(generating hyperchaos; developing chaos based pseudo random number generator(CPRNG) and chaotic multistream PRNG; secure communication via synchronization). They can also be used in cryptography, generic algorithms in optimization, control, etc.
基金Supported by the National Key Research and Development Program of China under Grant No 2017YFA0204600the National Natural Science Foundation of China under Grant No 61404002the Science and Technology Project of Hunan Province under Grant No 2015JC3041
文摘An analytical model for current-voltage behavior of amorphous In-Ga-Zn-O thin-film transistors（a-IGZO TFTs）with dual-gate structures is developed.The unified expressions for synchronous and asynchronous operating modes are derived on the basis of channel charges,which are controlled by gate voltage.It is proven that the threshold voltage of asynchronous dual-gate IGZO TFTs is adjusted in proportion to the ratio of top insulating capacitance to the bottom insulating capacitance（C_（TI）/C_（BI））.Incorporating the proposed model with Verilog-A,a touch-sensing circuit using dual-gate structure is investigated by SPICE simulations.Comparison shows that the touch sensitivity is increased by the dual-gate IGZO TFT structure.
基金supported by the National Natural Science Foundation of China(No.1017405790201011)+1 种基金the Key Project of Chinese Ministry of Education(No.2005-105148)the Research Fund for the Doctoral Program of Higher Education of China(No.20070613058)
文摘The V-shaped electro-optical properties control is investigated by an equivalent circuit model.Simu-lation results show that genuine V-shaped form is only observed at hysteresis inversion frequency,and be-low and above this frequency an anomalous and normal hysteresis are observed.And the inversion fre-quency decreases with the resistance of ferroelectric liquid crystal(FLC)layer following logf_i=-alogR_(LC)+b .The results are in good accordance with the reported experimental results.
