The electromagnetic wave propagations and their coupling characteristics in magnetized plasma near the antenna of ion cyclotron range of frequencies(ICRF)is studied based on self-developed 3DFEM-IA code.This code effe...The electromagnetic wave propagations and their coupling characteristics in magnetized plasma near the antenna of ion cyclotron range of frequencies(ICRF)is studied based on self-developed 3DFEM-IA code.This code effectively resolves the three-dimensional(3D)geometry and the electromagnetic field using the finite element method.Our findings reveal that the distributions of electromagnetic fields and energy flow density significantly depend on the antenna phases,surface current density on the antenna straps,and background plasma density.Notably,the non-uniform surface current density on the antenna straps,resulting from the presence of induced currents,contributes to a reduction in coupling power within the edge plasma.Furthermore,the calculated coupling impedance increases with plasma density,corroborating well with experimental measurements.展开更多
A program developed with COMSOL software integrates EAST four-strap antenna coupling with the double-stub Ferrite tuners(FT)impedance matching,obtaining physical quantities crucial for predicting the overall performan...A program developed with COMSOL software integrates EAST four-strap antenna coupling with the double-stub Ferrite tuners(FT)impedance matching,obtaining physical quantities crucial for predicting the overall performance of the ion cyclotron resonance heating(ICRH)antenna and matching system.These quantities encompass S-matrix,port complex impedance,reflection coefficients,electric field and voltage distribution,and optimal matching settings.In this study,we explore the relationship between S-matrix,reflection coefficients,port complex impedance,and frequency.Then,we analyze the impact of Faraday screens placement position and transparency,the distance from the Faraday screen(FS)to the current straps(CS),the relative distance between ports,and the characteristic impedance of the transmission line on the coupling characteristic impedance of the EAST ICRH system.Finally,we simulate the electric field distribution and voltage distribution of the EAST ICRH system for plasma heating with double-stub FT impedance matching.Using optimized parameters,the coupling power of the ICRH system can be approximately doubled.The results present herein may offer guidance for the design of high-power,long-pulse operation ICRH antenna systems.展开更多
This paper presents the heave responses and the moonpool water motions of a truss Spar platform with semi-closed moonpool in random waves. A 2-DOF（degree of freedom） coupling dynamical equations of the platform heav...This paper presents the heave responses and the moonpool water motions of a truss Spar platform with semi-closed moonpool in random waves. A 2-DOF（degree of freedom） coupling dynamical equations of the platform heave and vertical motions of the moonpool water are derived. The linear wave theory is used to simulate the random waves. The response statistical values and the power spectrums are calculated to analyze the mutual influences between the platform heave and the moonpool water motions for different opening ratios of the moonpool. The effect of coupling parameters on the platform heave and the moonpool water motions are analyzed. The results show that motions of the moonpool water significantly affected the platform heave when the characteristic wave period is far away from the natural period of the platform heave, and different moonpool opening ratios lead to different heave amplitudes of the platform. In the actual design, an optimized moonpool opening ratio can be designed to reduce heave motions of the platform.展开更多
Over the last decade,power systems in the world have suffered a number of blackouts;caused by cascading failures.Such incidents resulted in major economic losses and social impacts,induced great concerns on the grid s...Over the last decade,power systems in the world have suffered a number of blackouts;caused by cascading failures.Such incidents resulted in major economic losses and social impacts,induced great concerns on the grid security and prompted people to understand and analyze the mechanism of the power system's cascading failures and blackouts.Conventional analysis on power systems constructs a detailed model of every component of the system,and focuses on dynamic behaviors of individual components.Therefore,it is difficult to uncover the global dynamic characteristic while deeply studying the cascading failures and the mechanism of large blackouts.The complex system theory can provide global perspectives of cascading blackouts.展开更多
Inductive coupled wireless power transfer(WPT)system transfers energy through the magnetic field.The magnetics field distribution of WPT system has significantly influence on the transmission efficiency and misalignme...Inductive coupled wireless power transfer(WPT)system transfers energy through the magnetic field.The magnetics field distribution of WPT system has significantly influence on the transmission efficiency and misalignment tolerance.This study investigates the magnetic field distribution of WPT system and presents a magnetic field distribution analytical model for WPT system.The analytical model is based on Fourier analysis method,and it can be applied in the cases of coil with air core and with Ferrite core.Furthermore,the finite element simulation model and experiment are conducted.The results of analysis,simulation and experiment are in good agreement.展开更多
We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance...We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.展开更多
Heat exchanger systems(HXSs)or heat recovery steam generators(HRSGs)are commonly used in 100 kW to 50 MW combined cooling,heating,and power(CCHP)systems.Power flow coupling(PFC)is found in HXSs and is complex for rese...Heat exchanger systems(HXSs)or heat recovery steam generators(HRSGs)are commonly used in 100 kW to 50 MW combined cooling,heating,and power(CCHP)systems.Power flow coupling(PFC)is found in HXSs and is complex for researchers to quantify.This could possibly mislead the dispatch schedule and result in the inaccurate dispatch.PFC is caused by the inlet and outlet temperatures of each component,gas flow pressure variation,conductive medium flow rate,and atmosphere condition variation.In this paper,the expression of PFC is built by using quadratic functions to fit the non!inearit>of thermal dynamics.While fitting the model,the environmental condition needs prediction,which is calculated using phase space reconstruction(PSR)Kalman filter.In order to solve the complex quadratic dispatch model,a hybrid following electricity load(FEL)and following thermal load(FTL)mode for reducing the dimension of dispatch model,and a feasible zone analysis(FZA)method are proposed.As a result,the PFC problem of CCHP system is solved,and the dispatch cost,investment cost,and the maximum power requirements are optimized.In this paper,a case in Jinan,China is studied.The PFC model is proven to be more precise and accurate compared with traditional models.展开更多
Based on the high-speed development of the fiber laser in recent years, the development of researching 915 nm semiconductor laser as main pumping sources of the fiber laser is at a high speed. Because the beam quality...Based on the high-speed development of the fiber laser in recent years, the development of researching 915 nm semiconductor laser as main pumping sources of the fiber laser is at a high speed. Because the beam quality of the laser diode is very poor, the 915 nm laser diode is generally based on optical fiber coupling module to output the laser. Using the beam-shaping and fiber-coupling technology to improve the quality of output beam light, we present a kind of high-power and high-brightness semiconductor laser module, which can output 13.22 W through the optical fiber. Based on 915 nm GaAs semiconductor laser diode which has output power of 13.91 W, we describe a thoroughly detailed procedure for reshaping the beam output from the semiconductor laser diode and coupling the beam into the optical fiber of which the core diameter is 105 μm and the numerical aperture is 0.18. We get 13.22 W from the output fiber of the module at 14.5 A, the coupling efficiency of the whole module is 95.03% and the brightness is 1.5 MW/cm2-str. The output power of the single chip semiconductor laser module achieves the advanced level in the domestic use.展开更多
The rapid development of electric vehicles(EVs)is strengthening the bi-directional interactions between electric power networks(EPNs)and transportation networks(TNs)while providing opportunities to enhance the resilie...The rapid development of electric vehicles(EVs)is strengthening the bi-directional interactions between electric power networks(EPNs)and transportation networks(TNs)while providing opportunities to enhance the resilience of power systems towards extreme events.To quantify the temporal and spatial flexibility of EVs for charging and discharging,a novel dynamic traffic assignment(DTA)problem is proposed.The DTA problem is based on a link transmission model(LTM)with extended charging links,depicting the interaction between EVs and power systems.It models the charging rates as continuous variables by an energy boundary model.To consider the evacuation requirements of TNs and the uncertainties of traffic conditions,the DTA problem is extended to a two-stage distributionally robust version.It is further incorporated into a two-stage distributionally robust unit commitment problem to balance the enhancement of EPNs and the performance of TNs.The problem is reformulated into a mixed-integer linear programming problem and solved by off-the-shelf commercial solvers.Case studies are performed on two test networks.The effectiveness is verified by the numerical results,e.g.,reducing the load shedding amount without increasing the unmet traffic demand.展开更多
This study investigated the inductively coupled plasma etching reactor and RF coils developed by North Microelectronic Corporation. Full three dimensional simulations were made at different discharge conditions. The s...This study investigated the inductively coupled plasma etching reactor and RF coils developed by North Microelectronic Corporation. Full three dimensional simulations were made at different discharge conditions. The simulations examined and compared the distribution and non-uniformity of several plasma parameters at a fixed position upon the wafer at different pressures and coil currents. These parameters included electron density, electron temperature and power deposition. The results demonstrate that the electron density, power deposition and uniformity increase with either higher pressure or stronger coil currents, while the electron temperature decreases at this condition. Coil number increase can reduce the non-uniformity of parameters in the spatial distribution. The linear relationship between power deposition and electron density does not always exist. The comparison between simulation results and experiment results is also presented in the paper.展开更多
The GFL-GFM hybrid wind farm (HWF) combines the voltage source control advantages of grid-forming (GFM) wind turbines (WTs) with the current source control advantages of grid-following (GFL) wind turbines. It becomes ...The GFL-GFM hybrid wind farm (HWF) combines the voltage source control advantages of grid-forming (GFM) wind turbines (WTs) with the current source control advantages of grid-following (GFL) wind turbines. It becomes a new type of large-scale grid-connected wind power generation. In this paper, we propose an HWF frequency-voltage active support based on GFL and GFM hierarchical subgroup control. It aims to realize the support of active power and reactive power under the premise of ensuring system stability. The strategy consists of the determination of the control objectives of the GFM-GFL subgroups, the distributed control (DC) of the GFM-GFL subgroups, and the adaptive control and switching of each unit of the GFM and GFL groups. The GFM-group maintains the grid-connected voltage stability and the GFL-group exhausts the active support. DC at the group level and adaptive control at the unit level are included under the hierarchy of the respective objectives. Finally, a GFL-GFM HWF model is established on the MATLAB/Simulink platform, and the simulation verifies that the proposed strategy can realize the enhancement of the frequency-voltage support capability of the HWF under the premise of grid-connected stability.展开更多
Based on its prototype of machine-isolator-foundation systems, a theoretical model for dynamic coupled linear system is established, in which both the passive and active control factors are considered. Power flow is u...Based on its prototype of machine-isolator-foundation systems, a theoretical model for dynamic coupled linear system is established, in which both the passive and active control factors are considered. Power flow is used as the cost function to evaluate the isolation effectiveness. And the transmission of vibratory power flow from a vibrating rigid body into a simply supported thin panel through passive isolators and actuators is investigated numerically. The active control strategy is summarized in the conclusion.展开更多
The bump-on-tail(BOT)instability is generally caused by a beam of energetic particles existing in relatively cold background plasma.The employment of second-stage wave-driven module in the variable specific impulse ma...The bump-on-tail(BOT)instability is generally caused by a beam of energetic particles existing in relatively cold background plasma.The employment of second-stage wave-driven module in the variable specific impulse magnetoplasma rocket(VASIMR)yields the production of energetic ions,which could drive the BOT instability.The present work explores this possibility for the first time via numerical simulations based on the experimental data on the VASIMR,i.e.,referring to VX-50.It is found that the BOT instability does exist even in the plume region away from antenna.The results indicate that velocity space diffusion provides a stabilizing effect on the nonlinear evolution of waves,while dissipation in the bulk plasma essentially impedes it.To show the practical values implied by these computations,the influences of this BOT instability on the power coupling and thrust are investigated particularly.These findings are valuable for VASIMR,as well as other plasma thrusters that yield energetic particles inside relatively cold background plasma,to suppress BOT instability and thus increase the power coupling efficiency and thrust performance.展开更多
基金Project supported by the National MCF Energy Research and Development Program(Grant No.2022YFE03190100)the National Natural Science Foundation of China(Grant Nos.12422513,12105035,and U21A20438)the Xiaomi Young Talents Program。
文摘The electromagnetic wave propagations and their coupling characteristics in magnetized plasma near the antenna of ion cyclotron range of frequencies(ICRF)is studied based on self-developed 3DFEM-IA code.This code effectively resolves the three-dimensional(3D)geometry and the electromagnetic field using the finite element method.Our findings reveal that the distributions of electromagnetic fields and energy flow density significantly depend on the antenna phases,surface current density on the antenna straps,and background plasma density.Notably,the non-uniform surface current density on the antenna straps,resulting from the presence of induced currents,contributes to a reduction in coupling power within the edge plasma.Furthermore,the calculated coupling impedance increases with plasma density,corroborating well with experimental measurements.
基金supported by National Magnetic Confinement Fusion Energy Development Research Project(Nos.2022YFE03070003 and 2019YFE03070000)Natural Science Foundation of Hunan Province(No.2020JJ4515)+6 种基金Key Projects of Hunan Provincial Department of Education(No.20A432)the Government Sponsored Study Abroad Program of the Chinese Scholarship Council(CSC)(No.202108430056)Anhui Provincial Natural Science Foundation(No.2308085MA23)IAEA Coordinated Research Project F43026(No.26480)the National Key Research&Development Program of China(No.2018YFE0303103)National Natural Science Foundation of China(Nos.11875287 and 12275314)Anhui Provincial Key Research&Development Project(No.205258180096)。
文摘A program developed with COMSOL software integrates EAST four-strap antenna coupling with the double-stub Ferrite tuners(FT)impedance matching,obtaining physical quantities crucial for predicting the overall performance of the ion cyclotron resonance heating(ICRH)antenna and matching system.These quantities encompass S-matrix,port complex impedance,reflection coefficients,electric field and voltage distribution,and optimal matching settings.In this study,we explore the relationship between S-matrix,reflection coefficients,port complex impedance,and frequency.Then,we analyze the impact of Faraday screens placement position and transparency,the distance from the Faraday screen(FS)to the current straps(CS),the relative distance between ports,and the characteristic impedance of the transmission line on the coupling characteristic impedance of the EAST ICRH system.Finally,we simulate the electric field distribution and voltage distribution of the EAST ICRH system for plasma heating with double-stub FT impedance matching.Using optimized parameters,the coupling power of the ICRH system can be approximately doubled.The results present herein may offer guidance for the design of high-power,long-pulse operation ICRH antenna systems.
基金financially supported by the National Natural Science Foundation of China(Grant No.51179125)the Innovation Foundation of Tianjin University(Grant No.1301)
文摘This paper presents the heave responses and the moonpool water motions of a truss Spar platform with semi-closed moonpool in random waves. A 2-DOF（degree of freedom） coupling dynamical equations of the platform heave and vertical motions of the moonpool water are derived. The linear wave theory is used to simulate the random waves. The response statistical values and the power spectrums are calculated to analyze the mutual influences between the platform heave and the moonpool water motions for different opening ratios of the moonpool. The effect of coupling parameters on the platform heave and the moonpool water motions are analyzed. The results show that motions of the moonpool water significantly affected the platform heave when the characteristic wave period is far away from the natural period of the platform heave, and different moonpool opening ratios lead to different heave amplitudes of the platform. In the actual design, an optimized moonpool opening ratio can be designed to reduce heave motions of the platform.
文摘Over the last decade,power systems in the world have suffered a number of blackouts;caused by cascading failures.Such incidents resulted in major economic losses and social impacts,induced great concerns on the grid security and prompted people to understand and analyze the mechanism of the power system's cascading failures and blackouts.Conventional analysis on power systems constructs a detailed model of every component of the system,and focuses on dynamic behaviors of individual components.Therefore,it is difficult to uncover the global dynamic characteristic while deeply studying the cascading failures and the mechanism of large blackouts.The complex system theory can provide global perspectives of cascading blackouts.
基金supported by Beijing Nova Program(Grant No.20220484153).
文摘Inductive coupled wireless power transfer(WPT)system transfers energy through the magnetic field.The magnetics field distribution of WPT system has significantly influence on the transmission efficiency and misalignment tolerance.This study investigates the magnetic field distribution of WPT system and presents a magnetic field distribution analytical model for WPT system.The analytical model is based on Fourier analysis method,and it can be applied in the cases of coil with air core and with Ferrite core.Furthermore,the finite element simulation model and experiment are conducted.The results of analysis,simulation and experiment are in good agreement.
基金Project supported by the National High-Tech R&D Program of China(No.2013AA09A414)the National Natural Science Foundation of China(No.51221004)the Interdisciplinary Research Foundation of Zhejiang University(No.2012HY003A)
文摘We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.
基金the National Natural Science Foundation of China(No.61733010).
文摘Heat exchanger systems(HXSs)or heat recovery steam generators(HRSGs)are commonly used in 100 kW to 50 MW combined cooling,heating,and power(CCHP)systems.Power flow coupling(PFC)is found in HXSs and is complex for researchers to quantify.This could possibly mislead the dispatch schedule and result in the inaccurate dispatch.PFC is caused by the inlet and outlet temperatures of each component,gas flow pressure variation,conductive medium flow rate,and atmosphere condition variation.In this paper,the expression of PFC is built by using quadratic functions to fit the non!inearit>of thermal dynamics.While fitting the model,the environmental condition needs prediction,which is calculated using phase space reconstruction(PSR)Kalman filter.In order to solve the complex quadratic dispatch model,a hybrid following electricity load(FEL)and following thermal load(FTL)mode for reducing the dimension of dispatch model,and a feasible zone analysis(FZA)method are proposed.As a result,the PFC problem of CCHP system is solved,and the dispatch cost,investment cost,and the maximum power requirements are optimized.In this paper,a case in Jinan,China is studied.The PFC model is proven to be more precise and accurate compared with traditional models.
文摘Based on the high-speed development of the fiber laser in recent years, the development of researching 915 nm semiconductor laser as main pumping sources of the fiber laser is at a high speed. Because the beam quality of the laser diode is very poor, the 915 nm laser diode is generally based on optical fiber coupling module to output the laser. Using the beam-shaping and fiber-coupling technology to improve the quality of output beam light, we present a kind of high-power and high-brightness semiconductor laser module, which can output 13.22 W through the optical fiber. Based on 915 nm GaAs semiconductor laser diode which has output power of 13.91 W, we describe a thoroughly detailed procedure for reshaping the beam output from the semiconductor laser diode and coupling the beam into the optical fiber of which the core diameter is 105 μm and the numerical aperture is 0.18. We get 13.22 W from the output fiber of the module at 14.5 A, the coupling efficiency of the whole module is 95.03% and the brightness is 1.5 MW/cm2-str. The output power of the single chip semiconductor laser module achieves the advanced level in the domestic use.
文摘The rapid development of electric vehicles(EVs)is strengthening the bi-directional interactions between electric power networks(EPNs)and transportation networks(TNs)while providing opportunities to enhance the resilience of power systems towards extreme events.To quantify the temporal and spatial flexibility of EVs for charging and discharging,a novel dynamic traffic assignment(DTA)problem is proposed.The DTA problem is based on a link transmission model(LTM)with extended charging links,depicting the interaction between EVs and power systems.It models the charging rates as continuous variables by an energy boundary model.To consider the evacuation requirements of TNs and the uncertainties of traffic conditions,the DTA problem is extended to a two-stage distributionally robust version.It is further incorporated into a two-stage distributionally robust unit commitment problem to balance the enhancement of EPNs and the performance of TNs.The problem is reformulated into a mixed-integer linear programming problem and solved by off-the-shelf commercial solvers.Case studies are performed on two test networks.The effectiveness is verified by the numerical results,e.g.,reducing the load shedding amount without increasing the unmet traffic demand.
基金supported by North Microelectronic Corporation (NMC).
文摘This study investigated the inductively coupled plasma etching reactor and RF coils developed by North Microelectronic Corporation. Full three dimensional simulations were made at different discharge conditions. The simulations examined and compared the distribution and non-uniformity of several plasma parameters at a fixed position upon the wafer at different pressures and coil currents. These parameters included electron density, electron temperature and power deposition. The results demonstrate that the electron density, power deposition and uniformity increase with either higher pressure or stronger coil currents, while the electron temperature decreases at this condition. Coil number increase can reduce the non-uniformity of parameters in the spatial distribution. The linear relationship between power deposition and electron density does not always exist. The comparison between simulation results and experiment results is also presented in the paper.
基金supported by National Key R&D Program of China(No.2022YFB4202304).
文摘The GFL-GFM hybrid wind farm (HWF) combines the voltage source control advantages of grid-forming (GFM) wind turbines (WTs) with the current source control advantages of grid-following (GFL) wind turbines. It becomes a new type of large-scale grid-connected wind power generation. In this paper, we propose an HWF frequency-voltage active support based on GFL and GFM hierarchical subgroup control. It aims to realize the support of active power and reactive power under the premise of ensuring system stability. The strategy consists of the determination of the control objectives of the GFM-GFL subgroups, the distributed control (DC) of the GFM-GFL subgroups, and the adaptive control and switching of each unit of the GFM and GFL groups. The GFM-group maintains the grid-connected voltage stability and the GFL-group exhausts the active support. DC at the group level and adaptive control at the unit level are included under the hierarchy of the respective objectives. Finally, a GFL-GFM HWF model is established on the MATLAB/Simulink platform, and the simulation verifies that the proposed strategy can realize the enhancement of the frequency-voltage support capability of the HWF under the premise of grid-connected stability.
文摘Based on its prototype of machine-isolator-foundation systems, a theoretical model for dynamic coupled linear system is established, in which both the passive and active control factors are considered. Power flow is used as the cost function to evaluate the isolation effectiveness. And the transmission of vibratory power flow from a vibrating rigid body into a simply supported thin panel through passive isolators and actuators is investigated numerically. The active control strategy is summarized in the conclusion.
基金supported by the National Natural Science Foundation of China(92271113 and 12105324)the Fundamental Research Funds for the Central Universities(2022CDJQY-003)the Chongqing Entrepreneurship and Innovation Support Program for Overseas Returnees(CX2022004).
文摘The bump-on-tail(BOT)instability is generally caused by a beam of energetic particles existing in relatively cold background plasma.The employment of second-stage wave-driven module in the variable specific impulse magnetoplasma rocket(VASIMR)yields the production of energetic ions,which could drive the BOT instability.The present work explores this possibility for the first time via numerical simulations based on the experimental data on the VASIMR,i.e.,referring to VX-50.It is found that the BOT instability does exist even in the plume region away from antenna.The results indicate that velocity space diffusion provides a stabilizing effect on the nonlinear evolution of waves,while dissipation in the bulk plasma essentially impedes it.To show the practical values implied by these computations,the influences of this BOT instability on the power coupling and thrust are investigated particularly.These findings are valuable for VASIMR,as well as other plasma thrusters that yield energetic particles inside relatively cold background plasma,to suppress BOT instability and thus increase the power coupling efficiency and thrust performance.
