The coupling of lower hybrid wave to the plasma is a crucial issue for efficient current drive in tokamaks. This paper establishes a new coupling model which assumes the antenna to be a curved face and the plasma to b...The coupling of lower hybrid wave to the plasma is a crucial issue for efficient current drive in tokamaks. This paper establishes a new coupling model which assumes the antenna to be a curved face and the plasma to be a cylinder. Power spectrum considering the coupling between wave-guides in both poloidal and toroidal direction is simply estimated and discussed. The effect of the poloidal wave vector on wave propagation, power deposition and driven current is also investigated with the help of lower hybrid current drive code. Results show that the poloidal wave vector affects the ray tracing, and also has effect on power deposition and driven current. The effect of the poloidal wave vector on power deposition and driven current profile depends on plasma parameters. Preliminary studies suggest that it seems possible to control the current profile by adjusting the poloidal phase difference between the waveguide in poloidal direction.展开更多
The thermal-electrical characteristic of a GaN light-emitting diode （LED） with the hybrid transparent conductive layers （TCLs） of graphene （Gr） and NiOx is investigated by a finite element method. It is indicate...The thermal-electrical characteristic of a GaN light-emitting diode （LED） with the hybrid transparent conductive layers （TCLs） of graphene （Gr） and NiOx is investigated by a finite element method. It is indicated that the LED with the compound TCL of 3-layer Gr and 1 nm NiOx has the best thermal-electrical performance from the view point of the maximum temperature and the current density deviation of multiple quantum wells, and the maximum temperature occurs near the n-electrode rather than p-electrode. Furthermore, to depress the current crowding on the LED, the electrode pattern parameters including p- and n-electrode length, p-electrode buried depth and the distance of n-electrode to active area are optimized. It is found that either increasing p- or n-electrode length and buried depth or decreasing the distance of n-electrode from the active area will decrease the temperature of the LED, while the increase of the n-electrode length has more prominent effect. Typically, when the n-electrode length increases to 0.8 times of the chip size, the temperature of the GaN LED with the inm NiOx/3-1ayer-Gr hybrid TCLs could drop about 7K and the current density uniformity could increase by 23.8%, compared to 0.4 times of the chip size. This new finding will be beneficial for improvement of the thermal- electrical performance of LEDs with various conductive TCLs such as NiOx/Gr or ITO/Gr as current spreading layers.展开更多
In this paper, a plug-in hybrid electrical vehicle(PHEV) is taken as the research object, and its dynamic performance and economic performance are taken as the research goals. Battery charge-sustaining(CS) period is d...In this paper, a plug-in hybrid electrical vehicle(PHEV) is taken as the research object, and its dynamic performance and economic performance are taken as the research goals. Battery charge-sustaining(CS) period is divided into power mode and economy mode. Energy management strategy designing methods of power mode and economy mode are proposed. Maximum velocity, acceleration performance and fuel consumption are simulated during the CS period in the AVL CRUISE simulation environment. The simulation results indicate that the maximum velocity and acceleration time of the power mode are better than those in the economy mode. Fuel consumption of the economy mode is better than that in the power mode. Fuel consumption of PHEV during the CS period is further improved by using the methods proposed in this paper, and this is meaningful for research and development of PHEV.展开更多
This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure o...This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.展开更多
The superconducting tokamak HT-7U [1] has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW /2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the...The superconducting tokamak HT-7U [1] has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW /2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the most efficient non-induction device can heat the plasma and drive the plasma current has been efficiently in operation 'owl and a particular design of the 2.8 MW/-35 kV high-voltage DC power supply has been already completed and will apply to the klystron of LHCD on HT-7 and the future HT-7U, and the project of the power supply has been examined and approved professionally by an authorized group of high-level specialist in the institute of Plasma Physics. The detailed design of the power supply and the simulation results are referred in the paper.展开更多
Particle-in-cell （PIC） simulation method has been proved to be a good candidate to study the interactions between plasmas and radio-frequency waves. However, for waves in the lower hybrid range of frequencies, a ful...Particle-in-cell （PIC） simulation method has been proved to be a good candidate to study the interactions between plasmas and radio-frequency waves. However, for waves in the lower hybrid range of frequencies, a full PIC simulation is not efficient due to its high computational cost. In this work, a gyro-kinetic electron and fully-kinetic ion （GeFi） particle simulation model is applied to study the propagations and mode conversion processes of lower hybrid waves （LHWs） in plasmas. With this method, the computational efficiency of LHW simulations is greatly increased by using a larger grid size and time step. The simulation results in the linear regime are validated by comparison with the linear theory.展开更多
Based on the control theories of PID, fuzzy logic and expert PID, the driver models are built and applied in the forward simulation for hybrid electric vehicles （HEV）. The impact to the vehicle speed tracking and th...Based on the control theories of PID, fuzzy logic and expert PID, the driver models are built and applied in the forward simulation for hybrid electric vehicles （HEV）. The impact to the vehicle speed tracking and the fuel economy is compared among the different driver models. The different human-simulated characteristics of the driver models are emphatically analyzed. The analysis results indicate that the driver models based on PID, simple fuzzy logic and expert PID are corresponding to the handling characteristics of different drives. The driver models of different human-simulated characteristics bring the handling divergence of drivers with different driving level and habit to the HEV forward simulation, and that is significant to the all-around verification and validation of the control strategy for HEV. System simulation results of different driver models validate the impact of driver models to the dynamic and fuel economy performance of HEV.展开更多
Hybrid nematic films have been studied by Monte Carlo simulations using a lattice spin model, in which the pair potential is spatially anisotropic and dependent on elastic constants of liquid crystals. We confirm in t...Hybrid nematic films have been studied by Monte Carlo simulations using a lattice spin model, in which the pair potential is spatially anisotropic and dependent on elastic constants of liquid crystals. We confirm in the thin hybrid nematic film the existence of a biaxially nonbent structure and the structure transition from the biaxial to the bent-director structure, which is similar to the result obtained using the Lebwoh-Lasher model. However, the step-like director＇s profile, characteristic for the biaxial structure, is spatially asymmetric in the film because the pair potential leads to K1 ≠ K3. We estimate the upper cell thickness to be 69 spin layers, in which the biaxial structure can be found.展开更多
In order to effectively imitate the dynamic operation characteristics of the HVDC （high voltage direct current） power transmission system at a real ±500kV HVDC transmission project, the electromechanical-electr...In order to effectively imitate the dynamic operation characteristics of the HVDC （high voltage direct current） power transmission system at a real ±500kV HVDC transmission project, the electromechanical-electromagnetic transient hybrid simulation was carried out based on advanced digital power system simulator （ADPSS）. In the simulation analysis, the built hybrid model＇s dynamic response outputs under three different fault conditions are considered, and by comparing with the selected fault recording waveforms, the validities of the simulation waveforms are estimated qualitatively. It can be ascertained that the hybrid simulation model has the ability to describe the HVDC system＇s dynamic change trends well under some special fault conditions.展开更多
A linear simulation study of energetic passing particle-driven low-frequency fishbone instability in tokamak plasmas has been carried out using the global kinetic-MHD(magnetohydrodynamics)hybrid code M3D-K.This work i...A linear simulation study of energetic passing particle-driven low-frequency fishbone instability in tokamak plasmas has been carried out using the global kinetic-MHD(magnetohydrodynamics)hybrid code M3D-K.This work is focused on the interaction of energetic passing beam ions and n=1 mode with a monotonic safety factor q profile and q_(0)<1.Specifically,the stability and mode frequency as well as mode structure of the n=1mode are calculated for scans of parameter values of beam ion beta,beam ion injection energy,beam ion orbit width,beam ion beta profile,as well as background plasma beta.The excited modes are identified as a low-frequency fishbone with the corresponding resonance of w_(φ)+w_(θ)=w,where w_(φ)is the beam ion toroidal transit frequency and w_(θ)is the beam ion poloidal transit frequency.The simulated mode frequency is approximately proportional to the beam ion injection energy and beam ion orbit width.The mode structure is similar to that of internal kink mode.These simulation results are similar to the analytic theory of Yu et al.展开更多
To realize the efficient transient simulation of a grid-connected power generation system based on multiple inverters, this paper proposes a hybrid simulation method integrating the models of electromagnetic transient...To realize the efficient transient simulation of a grid-connected power generation system based on multiple inverters, this paper proposes a hybrid simulation method integrating the models of electromagnetic transient and dynamic phasors. Based on a demonstration of the concepts and properties of dynamic phasors, the models of single-phase and three-phase inverters described by dynamic phasors are established first. Considering the numerical compatibility problem between dynamic phasors and instantaneous values, an interface scheme between dynamic phasors and instantaneous values is designed, and the efficiency and precision differences of various transformation methods are compared in detail.Finally, by utilizing MATLAB/Simulink, a hybrid simulation platform of a multi-inverter grid-connected system is built, and the efficiency and accuracy of the hybrid simulation are validated via comparison with the full electromagnetic transient simulation.展开更多
To implement structural hybrid simulation independent of the control system of any testing equipment in civil engineering, an external command control approach is put forward. Several setup technologies and the corres...To implement structural hybrid simulation independent of the control system of any testing equipment in civil engineering, an external command control approach is put forward. Several setup technologies and the corresponding API approaches are investigated to simultaneously combine numerical simulation with physical testing. Hybrid program technology is put forward and described in detail, using Visual C++ program to effectively and accurately control testing equipment and MATLAB program to implement numerical simulation with easy extension. The control program of testing equipment and numerical simulation program are integrated by calling MATLAB engine in Visual C++. A hybrid simulation about a full-scale six-story masonry structure is carried out. The testing results manifest that the external command control approach has the versatility because of simple hardware connection and control program independent on control software of testing equipment; powerful program function of Visual C++ and flexible program of MATLAB are integrated by hybrid program technology; hybrid simulation system provides a realistic and cost-effective testing platform that enables earthquake engineer researchers to accurately and efficiently capture the seismic performance of large or complex structures without having to carry out physical testing of the entire structure.展开更多
In this work,a new hybrid MPGD consisting of two GEM foils and a metallic mesh was proposed.Based on the simulation studies,this design can significantly reduce the rise time of signal and has a better performance in ...In this work,a new hybrid MPGD consisting of two GEM foils and a metallic mesh was proposed.Based on the simulation studies,this design can significantly reduce the rise time of signal and has a better performance in respect of particle identification compared with the triple GEM design.The gain with various voltages setting was computed in order to provide us references for future experiment.The simulation results also show that the time and space resolution compared to the triple GEM detector are also improved.The time and space resolution of hybrid detector with Ar/CO_2(70/30) and Ar/isobutane(95/5) were investigated for various drift electric field intensities.This new hybrid detector shows excellent potential for both fundamental research and imaging applications.展开更多
By performing one-dimensional （l-D） hybrid simulations, we analyze in detail the parametric instabilities of the Alfv^n waves with a spectrum in a low beta plasma. The parametric instabilities experience two stages....By performing one-dimensional （l-D） hybrid simulations, we analyze in detail the parametric instabilities of the Alfv^n waves with a spectrum in a low beta plasma. The parametric instabilities experience two stages. In the first stage, the density modes are excited and immediately couple with the pump Alfv6n waves. In the second stage, each pump Alfv^n wave decays into a density mode and a daughter Alfv6n mode similar to the monochromatic cases. Ftlrthermore, the proton velocity beam will also be formed after the saturation of the parametric instabilities. When the plasma beta is high, the parametric decay in the second stage will be strongly suppressed.展开更多
Single-photon sensors are novel devices with extremely high single-photon sensitivity and temporal resolution.However,these advantages also make them highly susceptible to noise.Moreover,single-photon cameras face sev...Single-photon sensors are novel devices with extremely high single-photon sensitivity and temporal resolution.However,these advantages also make them highly susceptible to noise.Moreover,single-photon cameras face severe quantization as low as 1 bit/frame.These factors make it a daunting task to recover high-quality scene information from noisy single-photon data.Most current image reconstruction methods for single-photon data are mathematical approaches,which limits information utilization and algorithm performance.In this work,we propose a hybrid information enhancement model which can significantly enhance the efficiency of information utilization by leveraging attention mechanisms from both spatial and channel branches.Furthermore,we introduce a structural feature enhance module for the FFN of the transformer,which explicitly improves the model's ability to extract and enhance high-frequency structural information through two symmetric convolution branches.Additionally,we propose a single-photon data simulation pipeline based on RAW images to address the challenge of the lack of single-photon datasets.Experimental results show that the proposed method outperforms state-of-the-art methods in various noise levels and exhibits a more efficient capability for recovering high-frequency structures and extracting information.展开更多
A three-dimensional(3-D)global hybrid simulation is carried out for the generation and structure of magnetic reconnection in the magnetosheath due to interaction of an interplanetary Tangential Discontinuity(TD)with t...A three-dimensional(3-D)global hybrid simulation is carried out for the generation and structure of magnetic reconnection in the magnetosheath due to interaction of an interplanetary Tangential Discontinuity(TD)with the bow shock and magnetosphere.Runs are performed for solar wind TDs possessing diFFerent initial half-widths.As the TD propagates through the bow shock toward the magnetopause,it is greatly narrowed by a two-step compression processes,a "shock compression" followed by a subsequent "convective compression".In cases with a relatively thin solar wind TD,3-D patchy reconnection is initiated in the transmitted TD,forming magnetosheath flux ropes.Multiple components of ion particles are present in the velocity distribution in the magnetosheath merging,accompanied by ion heating.For cases with a relatively wide initial TD,a dominant single X-line appears in the subsolar magnetosheath after the transmitted TD is narrowed.A shock analysis is performed for the detailed structure of magnetic reconnection in the magnetosheath.Rotational Discontinuity(RD)/TimeDependent Intermediate Shock(TDIS)are found to dominate the reconnection layer,which and some weak slow shocks are responsible for the ion heating and acceleration.展开更多
Most protons in the solar wind belong to one of two different populations,the less dense beam protons and the denser core protons.The beam protons,with a velocity of(1-2)V_(A)(V_(A)is the local Alfvén speed),alwa...Most protons in the solar wind belong to one of two different populations,the less dense beam protons and the denser core protons.The beam protons,with a velocity of(1-2)V_(A)(V_(A)is the local Alfvén speed),always drift relative to the core protons;this kind of distribution is unstable and stimulates several kinds of wave mode.In this study,using a 2 D hybrid simulation model,we find that the original right-handed elliptically polarized Alfvén waves become linearly polarized,and eventually become right-handed and circularly polarized.Given that linearly polarized waves are a superposition of left-handed and right-handed waves,cyclotron resonance in the right-handed/left-handed component heats beam/core protons perpendicularly.The resonance between beam protons and right-handed polarized waves is stronger when the beam relative density is lower,resulting in more dramatic perpendicular heating of beam protons,whereas the situation is reversed when the beam relative density is larger.展开更多
We reversely analyzed the energy management strategy （EMS） for a single-shaft parallel hybrid electric vehicle （HEV）, and build a forward co-simulation platform based on Cruise and Matlab. The vehicle dynamics mod...We reversely analyzed the energy management strategy （EMS） for a single-shaft parallel hybrid electric vehicle （HEV）, and build a forward co-simulation platform based on Cruise and Matlab. The vehicle dynamics model is built with Cruise, and control model is set up with Matlab/Simulink environment. The data between the two models are transferred by the Matlab API interface in Cruise. After mechanical and signal connections are completed, we establish the computing tasks and take the simulations of vehicle＇ s power performance, economy, and emission performance. The simulation results match the actual measurement results, which show that the co-simulation platform is correct and feasible. The platform can be used not only for a basic simulation platform to optimize further EMS, but also for the development of actual control system.展开更多
Both current and pressure coupling schemes have been adopted in the hybrid kinetic–magnetohydrodynamic code CLT-K recently.Numerical equivalences between these two coupling schemes are strictly verified under differe...Both current and pressure coupling schemes have been adopted in the hybrid kinetic–magnetohydrodynamic code CLT-K recently.Numerical equivalences between these two coupling schemes are strictly verified under different approximations.First,when considering only the perturbed distribution function of energetic particles(EPs),the equivalence can be proved analytically.Second,when both the variations of the magnetic field and the EP distribution function are included,the current and pressure coupling schemes numerically produce the same result in the nonlinear simulations.On this basis,the influences of co-/counter-passing and trapped EPs on the linear stabilities of the m/n=2/1 tearing mode(TM)have been investigated(where m and n represent the poloidal and toroidal mode numbers,respectively).The results of scanningβh of EPs show that the co-passing and trapped EPs are found to stabilize the TM,while the counter-passing EPs tend to destabilize the TM.The behind(de)stabilization mechanisms of the TM by EPs are carefully analyzed.Furthermore,after exceeding critical EP betas,the same branch of the high-frequency mode is excited by co-/counterpassing and trapped EPs,which is identified as the m/n=2/1 energetic particle mode.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10575104 and 10875149)Dean Foundation of Hefei Institute of Physical Science,Chinese Academy of Sciences
文摘The coupling of lower hybrid wave to the plasma is a crucial issue for efficient current drive in tokamaks. This paper establishes a new coupling model which assumes the antenna to be a curved face and the plasma to be a cylinder. Power spectrum considering the coupling between wave-guides in both poloidal and toroidal direction is simply estimated and discussed. The effect of the poloidal wave vector on wave propagation, power deposition and driven current is also investigated with the help of lower hybrid current drive code. Results show that the poloidal wave vector affects the ray tracing, and also has effect on power deposition and driven current. The effect of the poloidal wave vector on power deposition and driven current profile depends on plasma parameters. Preliminary studies suggest that it seems possible to control the current profile by adjusting the poloidal phase difference between the waveguide in poloidal direction.
基金Supported by the Foundation of the State Key Laboratory of Mechanical Transmission of Chongqing University under Grant Nos SKLMT-KFKT-201419 and SKLM-ZZKT-2015Z16the National High-Technology Research and Development Program of China under Grant No 2015AA034801+4 种基金the National Natural Science Foundation of China under Grant Nos 11374359,11304405,11544010 and 11547305the Chongqing Education Commission Scientific Project under Grant No KJ132209the Natural Science Foundation of Chongqing under Grant Nos cstc2013jcyjA50031,cstc2015jcyjA50035 and cstc2015jcyjA1660the Fundamental Research Funds for the Central Universities under Grant Nos CDJZR14135502,CDJZR14300050,106112016CDJZR288805 and 106112015CDJXY300002the Sharing Fund of Large-scale Equipment of Chongqing University under Grant Nos 201512150017,201512150029 and 201512150030
文摘The thermal-electrical characteristic of a GaN light-emitting diode （LED） with the hybrid transparent conductive layers （TCLs） of graphene （Gr） and NiOx is investigated by a finite element method. It is indicated that the LED with the compound TCL of 3-layer Gr and 1 nm NiOx has the best thermal-electrical performance from the view point of the maximum temperature and the current density deviation of multiple quantum wells, and the maximum temperature occurs near the n-electrode rather than p-electrode. Furthermore, to depress the current crowding on the LED, the electrode pattern parameters including p- and n-electrode length, p-electrode buried depth and the distance of n-electrode to active area are optimized. It is found that either increasing p- or n-electrode length and buried depth or decreasing the distance of n-electrode from the active area will decrease the temperature of the LED, while the increase of the n-electrode length has more prominent effect. Typically, when the n-electrode length increases to 0.8 times of the chip size, the temperature of the GaN LED with the inm NiOx/3-1ayer-Gr hybrid TCLs could drop about 7K and the current density uniformity could increase by 23.8%, compared to 0.4 times of the chip size. This new finding will be beneficial for improvement of the thermal- electrical performance of LEDs with various conductive TCLs such as NiOx/Gr or ITO/Gr as current spreading layers.
文摘In this paper, a plug-in hybrid electrical vehicle(PHEV) is taken as the research object, and its dynamic performance and economic performance are taken as the research goals. Battery charge-sustaining(CS) period is divided into power mode and economy mode. Energy management strategy designing methods of power mode and economy mode are proposed. Maximum velocity, acceleration performance and fuel consumption are simulated during the CS period in the AVL CRUISE simulation environment. The simulation results indicate that the maximum velocity and acceleration time of the power mode are better than those in the economy mode. Fuel consumption of the economy mode is better than that in the power mode. Fuel consumption of PHEV during the CS period is further improved by using the methods proposed in this paper, and this is meaningful for research and development of PHEV.
基金supported by the State Grid Science and Technology Project (No.52999821N004)。
文摘This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.
文摘The superconducting tokamak HT-7U [1] has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW /2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the most efficient non-induction device can heat the plasma and drive the plasma current has been efficiently in operation 'owl and a particular design of the 2.8 MW/-35 kV high-voltage DC power supply has been already completed and will apply to the klystron of LHCD on HT-7 and the future HT-7U, and the project of the power supply has been examined and approved professionally by an authorized group of high-level specialist in the institute of Plasma Physics. The detailed design of the power supply and the simulation results are referred in the paper.
基金supported by Science Foundation of Institute of Plasma Physics Chinese Academy of Sciences(No.Y35ETY1304)the JSPSNRF-NSFC A3 Foresight Program in the Field of Plasma Physics(No.11261140328)+1 种基金National ITER Plans Program of China(No.2013GB111002)National Natural Science Foundation of China(No.11105178)
文摘Particle-in-cell （PIC） simulation method has been proved to be a good candidate to study the interactions between plasmas and radio-frequency waves. However, for waves in the lower hybrid range of frequencies, a full PIC simulation is not efficient due to its high computational cost. In this work, a gyro-kinetic electron and fully-kinetic ion （GeFi） particle simulation model is applied to study the propagations and mode conversion processes of lower hybrid waves （LHWs） in plasmas. With this method, the computational efficiency of LHW simulations is greatly increased by using a larger grid size and time step. The simulation results in the linear regime are validated by comparison with the linear theory.
基金Supported by the National Natural Science Foundation of China(50905018)
文摘Based on the control theories of PID, fuzzy logic and expert PID, the driver models are built and applied in the forward simulation for hybrid electric vehicles （HEV）. The impact to the vehicle speed tracking and the fuel economy is compared among the different driver models. The different human-simulated characteristics of the driver models are emphatically analyzed. The analysis results indicate that the driver models based on PID, simple fuzzy logic and expert PID are corresponding to the handling characteristics of different drives. The driver models of different human-simulated characteristics bring the handling divergence of drivers with different driving level and habit to the HEV forward simulation, and that is significant to the all-around verification and validation of the control strategy for HEV. System simulation results of different driver models validate the impact of driver models to the dynamic and fuel economy performance of HEV.
基金Project supported by the National Natural Science Foundation of China (Grants Nos 60736042 and 60878047)the Key Subject Construction Project of Hebei Province University
文摘Hybrid nematic films have been studied by Monte Carlo simulations using a lattice spin model, in which the pair potential is spatially anisotropic and dependent on elastic constants of liquid crystals. We confirm in the thin hybrid nematic film the existence of a biaxially nonbent structure and the structure transition from the biaxial to the bent-director structure, which is similar to the result obtained using the Lebwoh-Lasher model. However, the step-like director＇s profile, characteristic for the biaxial structure, is spatially asymmetric in the film because the pair potential leads to K1 ≠ K3. We estimate the upper cell thickness to be 69 spin layers, in which the biaxial structure can be found.
基金supported by the General Program of Chinese Postdoctoral Science Foundation under Grant No.2012M511595
文摘In order to effectively imitate the dynamic operation characteristics of the HVDC （high voltage direct current） power transmission system at a real ±500kV HVDC transmission project, the electromechanical-electromagnetic transient hybrid simulation was carried out based on advanced digital power system simulator （ADPSS）. In the simulation analysis, the built hybrid model＇s dynamic response outputs under three different fault conditions are considered, and by comparing with the selected fault recording waveforms, the validities of the simulation waveforms are estimated qualitatively. It can be ascertained that the hybrid simulation model has the ability to describe the HVDC system＇s dynamic change trends well under some special fault conditions.
基金the National MCF Energy R&D Program of China(Nos.2019YFE03030004 and 2019YFE03050001)National Natural Science Foundation of China(Nos.11975232 and 11975270)。
文摘A linear simulation study of energetic passing particle-driven low-frequency fishbone instability in tokamak plasmas has been carried out using the global kinetic-MHD(magnetohydrodynamics)hybrid code M3D-K.This work is focused on the interaction of energetic passing beam ions and n=1 mode with a monotonic safety factor q profile and q_(0)<1.Specifically,the stability and mode frequency as well as mode structure of the n=1mode are calculated for scans of parameter values of beam ion beta,beam ion injection energy,beam ion orbit width,beam ion beta profile,as well as background plasma beta.The excited modes are identified as a low-frequency fishbone with the corresponding resonance of w_(φ)+w_(θ)=w,where w_(φ)is the beam ion toroidal transit frequency and w_(θ)is the beam ion poloidal transit frequency.The simulated mode frequency is approximately proportional to the beam ion injection energy and beam ion orbit width.The mode structure is similar to that of internal kink mode.These simulation results are similar to the analytic theory of Yu et al.
基金supported by the State Grid Science and Technology Project (grant no. KJ2021-069)。
文摘To realize the efficient transient simulation of a grid-connected power generation system based on multiple inverters, this paper proposes a hybrid simulation method integrating the models of electromagnetic transient and dynamic phasors. Based on a demonstration of the concepts and properties of dynamic phasors, the models of single-phase and three-phase inverters described by dynamic phasors are established first. Considering the numerical compatibility problem between dynamic phasors and instantaneous values, an interface scheme between dynamic phasors and instantaneous values is designed, and the efficiency and precision differences of various transformation methods are compared in detail.Finally, by utilizing MATLAB/Simulink, a hybrid simulation platform of a multi-inverter grid-connected system is built, and the efficiency and accuracy of the hybrid simulation are validated via comparison with the full electromagnetic transient simulation.
基金Funded by National Natural Science Foundation of China under the Grant No.90715036Open Project of Jiangsu Key Laboratory of Structural Engineering (Grant No.ZD1004)Project of the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘To implement structural hybrid simulation independent of the control system of any testing equipment in civil engineering, an external command control approach is put forward. Several setup technologies and the corresponding API approaches are investigated to simultaneously combine numerical simulation with physical testing. Hybrid program technology is put forward and described in detail, using Visual C++ program to effectively and accurately control testing equipment and MATLAB program to implement numerical simulation with easy extension. The control program of testing equipment and numerical simulation program are integrated by calling MATLAB engine in Visual C++. A hybrid simulation about a full-scale six-story masonry structure is carried out. The testing results manifest that the external command control approach has the versatility because of simple hardware connection and control program independent on control software of testing equipment; powerful program function of Visual C++ and flexible program of MATLAB are integrated by hybrid program technology; hybrid simulation system provides a realistic and cost-effective testing platform that enables earthquake engineer researchers to accurately and efficiently capture the seismic performance of large or complex structures without having to carry out physical testing of the entire structure.
基金Supported by the National Natural Science Foundation of China(Nos.11135002,11275235,11405077 and 11575073)
文摘In this work,a new hybrid MPGD consisting of two GEM foils and a metallic mesh was proposed.Based on the simulation studies,this design can significantly reduce the rise time of signal and has a better performance in respect of particle identification compared with the triple GEM design.The gain with various voltages setting was computed in order to provide us references for future experiment.The simulation results also show that the time and space resolution compared to the triple GEM detector are also improved.The time and space resolution of hybrid detector with Ar/CO_2(70/30) and Ar/isobutane(95/5) were investigated for various drift electric field intensities.This new hybrid detector shows excellent potential for both fundamental research and imaging applications.
基金Supported by the National Natural Science Foundation of China under Grant Nos 41331067,41474125,41274144,41174124 and 41121003the National Basic Research Program of China under Grant Nos 2013CBA01503 and 2012CB825602the Key Research Program of Chinese Academy of Sciences under Grant No KZZD-EW-01-4
文摘By performing one-dimensional （l-D） hybrid simulations, we analyze in detail the parametric instabilities of the Alfv^n waves with a spectrum in a low beta plasma. The parametric instabilities experience two stages. In the first stage, the density modes are excited and immediately couple with the pump Alfv6n waves. In the second stage, each pump Alfv^n wave decays into a density mode and a daughter Alfv6n mode similar to the monochromatic cases. Ftlrthermore, the proton velocity beam will also be formed after the saturation of the parametric instabilities. When the plasma beta is high, the parametric decay in the second stage will be strongly suppressed.
文摘Single-photon sensors are novel devices with extremely high single-photon sensitivity and temporal resolution.However,these advantages also make them highly susceptible to noise.Moreover,single-photon cameras face severe quantization as low as 1 bit/frame.These factors make it a daunting task to recover high-quality scene information from noisy single-photon data.Most current image reconstruction methods for single-photon data are mathematical approaches,which limits information utilization and algorithm performance.In this work,we propose a hybrid information enhancement model which can significantly enhance the efficiency of information utilization by leveraging attention mechanisms from both spatial and channel branches.Furthermore,we introduce a structural feature enhance module for the FFN of the transformer,which explicitly improves the model's ability to extract and enhance high-frequency structural information through two symmetric convolution branches.Additionally,we propose a single-photon data simulation pipeline based on RAW images to address the challenge of the lack of single-photon datasets.Experimental results show that the proposed method outperforms state-of-the-art methods in various noise levels and exhibits a more efficient capability for recovering high-frequency structures and extracting information.
基金Supported by NSF grant ATM-0646442 to Auburn University and the National Natural Science Foundation of China(NSFC) grant 40640420563 to Wuhan University
文摘A three-dimensional(3-D)global hybrid simulation is carried out for the generation and structure of magnetic reconnection in the magnetosheath due to interaction of an interplanetary Tangential Discontinuity(TD)with the bow shock and magnetosphere.Runs are performed for solar wind TDs possessing diFFerent initial half-widths.As the TD propagates through the bow shock toward the magnetopause,it is greatly narrowed by a two-step compression processes,a "shock compression" followed by a subsequent "convective compression".In cases with a relatively thin solar wind TD,3-D patchy reconnection is initiated in the transmitted TD,forming magnetosheath flux ropes.Multiple components of ion particles are present in the velocity distribution in the magnetosheath merging,accompanied by ion heating.For cases with a relatively wide initial TD,a dominant single X-line appears in the subsolar magnetosheath after the transmitted TD is narrowed.A shock analysis is performed for the detailed structure of magnetic reconnection in the magnetosheath.Rotational Discontinuity(RD)/TimeDependent Intermediate Shock(TDIS)are found to dominate the reconnection layer,which and some weak slow shocks are responsible for the ion heating and acceleration.
基金supported by National Natural Science Foundation of China(Nos.11822401,41674177 and 41874208).
文摘Most protons in the solar wind belong to one of two different populations,the less dense beam protons and the denser core protons.The beam protons,with a velocity of(1-2)V_(A)(V_(A)is the local Alfvén speed),always drift relative to the core protons;this kind of distribution is unstable and stimulates several kinds of wave mode.In this study,using a 2 D hybrid simulation model,we find that the original right-handed elliptically polarized Alfvén waves become linearly polarized,and eventually become right-handed and circularly polarized.Given that linearly polarized waves are a superposition of left-handed and right-handed waves,cyclotron resonance in the right-handed/left-handed component heats beam/core protons perpendicularly.The resonance between beam protons and right-handed polarized waves is stronger when the beam relative density is lower,resulting in more dramatic perpendicular heating of beam protons,whereas the situation is reversed when the beam relative density is larger.
基金Supported by the National High Technology Research and Development Program of China("863"Program),(2011AAllA252)
文摘We reversely analyzed the energy management strategy （EMS） for a single-shaft parallel hybrid electric vehicle （HEV）, and build a forward co-simulation platform based on Cruise and Matlab. The vehicle dynamics model is built with Cruise, and control model is set up with Matlab/Simulink environment. The data between the two models are transferred by the Matlab API interface in Cruise. After mechanical and signal connections are completed, we establish the computing tasks and take the simulations of vehicle＇ s power performance, economy, and emission performance. The simulation results match the actual measurement results, which show that the co-simulation platform is correct and feasible. The platform can be used not only for a basic simulation platform to optimize further EMS, but also for the development of actual control system.
基金supported by National Natural Science Foundation of China(No.11835010)by the National Key Research and Development Program of China(Nos.2019YFE03030004 and 2022YFE031000001)。
文摘Both current and pressure coupling schemes have been adopted in the hybrid kinetic–magnetohydrodynamic code CLT-K recently.Numerical equivalences between these two coupling schemes are strictly verified under different approximations.First,when considering only the perturbed distribution function of energetic particles(EPs),the equivalence can be proved analytically.Second,when both the variations of the magnetic field and the EP distribution function are included,the current and pressure coupling schemes numerically produce the same result in the nonlinear simulations.On this basis,the influences of co-/counter-passing and trapped EPs on the linear stabilities of the m/n=2/1 tearing mode(TM)have been investigated(where m and n represent the poloidal and toroidal mode numbers,respectively).The results of scanningβh of EPs show that the co-passing and trapped EPs are found to stabilize the TM,while the counter-passing EPs tend to destabilize the TM.The behind(de)stabilization mechanisms of the TM by EPs are carefully analyzed.Furthermore,after exceeding critical EP betas,the same branch of the high-frequency mode is excited by co-/counterpassing and trapped EPs,which is identified as the m/n=2/1 energetic particle mode.
