With the advancement of more electric aircraft(MEA)technology,the application of electro-hydrostatic actuators(EHAs)in aircraft actuation systems has become increasingly prevalent.This paper focuses on the modeling an...With the advancement of more electric aircraft(MEA)technology,the application of electro-hydrostatic actuators(EHAs)in aircraft actuation systems has become increasingly prevalent.This paper focuses on the modeling and mode switching analysis of EHA used in the primary flight control actuation systems of large aircraft,addressing the challenges associated with mode switching.First,we analyze the functional architecture and operational characteristics of multi-mode EHA,and sumarize the operating modes and implementation methods.Based on the EHA system architecture,we then develop a theoretical mathematical model and a simulation model.Using the simulation model,we analyze the performance of the EHA during normal operation.Finally,the performance of the EHA during mode switching under various functional switching scenarios is investigated.The results indicate that the EHA meets the performance requirements in terms of accuracy,bandwidth,and load capacity.Additionally,the hydraulic cylinder operates smoothly during the EHA mode switching,and the response time for switching between different modes is less than the specified threshold.These findings validate the system performance of multi-mode EHA,which helps to improve the reliability of EHA and the safety of aircraft flight control systems.展开更多
In order to enhance the safety of autonomous driving vehicles,this work focuses on the issue of automatic-to-manual mode transition in the column electric power steering(C-EPS)system.First,we utilized an extended stat...In order to enhance the safety of autonomous driving vehicles,this work focuses on the issue of automatic-to-manual mode transition in the column electric power steering(C-EPS)system.First,we utilized an extended state observer to estimate the driver's steering torque and designed a steering mode transition unit.Second,we validated the mode switching function through an experimental platform.The results indicated that when using the extended state observer for torque estimation,the steering wheel angle and lower input angle errors were approximately±0.5%.The input and observed torque curves were closely aligned,demonstrating excellent tracking capability of the system.In addition,by adopting a steering mode conversion unit,the switch from autonomous control to manual control has been obtained,achieving a smooth and minimal change in steering wheel angle without significant bumps.The experimental results demonstrate that the designed mode switching strategy has the advantages of speed and smoothness,and has strong practical value.展开更多
The photovoltaic(PV)output process is inherently complex,often disrupted by a multitude of meteoro-logical factors,while conventional detection methods at PV power stations prove inadequate,compromising prediction acc...The photovoltaic(PV)output process is inherently complex,often disrupted by a multitude of meteoro-logical factors,while conventional detection methods at PV power stations prove inadequate,compromising prediction accuracy.To address this challenge,this paper introduces a power prediction method that leverages modal switching(MS),weight factor adjustment(WFA),and parallel long short-term memory(PALSTM).Initially,historical PV power station data is categorized into distinct modes based on global horizontal irradiance and converted solar angles.Correlation analysis is then employed to evaluate the impact of various meteorological factors on PV power,selecting those with strong correlations for each specific mode.Subsequently,the weights of meteorological parameters are optimized and adjusted,and a PALSTM neural network is constructed,with its parallel modal parameters refined through training.Depending on the prediction time and input data mode characteristics,the appropriate mode channel is selected to forecast PV power station generation.Ultimately,the feasibility of this method is validated through an illustrative analysis of measured data from an Australian PV power station.Comparative test results underscore the method’s advantages,particularly in scenarios where existing detection methods are lacking and meteorological factors frequently fluctuate,demonstrating its superior prediction accuracy and stability.展开更多
Based on analyzing the structure and working principle on electric vehicles （EVs） with dual motors coupled by planetarY gears, the control strategy of mode switching was proposed. The power interruption problem on E...Based on analyzing the structure and working principle on electric vehicles （EVs） with dual motors coupled by planetarY gears, the control strategy of mode switching was proposed. The power interruption problem on EVs with automatic mechanical transmission （AMT） shifting was resolved. Based on the speed-torque characteristics of the planetary gears and the principle of the auxiliary motor＇ s zero speed braking, control features of mode switching were introduced. The mode shifting between the main motor mode and dual motors coupled driving were studied. Matlab/Simulink was adopted as a platform to develop the simulation model of EVs with dual motors drive system and 3 gears AMT. Simulation results demonstrated that the power interruption of dual motors drive system was solved during mode switching. The power requirements of EVs were satisfied, too.展开更多
This paper explores and proposes a design solution of an integrated skip cycle mode （SCM） control circuit with a simple structure. The design is simulated and implemented with XD10H-1.0μm modular DIMOS 650 V proces...This paper explores and proposes a design solution of an integrated skip cycle mode （SCM） control circuit with a simple structure. The design is simulated and implemented with XD10H-1.0μm modular DIMOS 650 V process. In order to meet the requirement of a wide temperature range and high yields of products, the schematic extracted from the layout is simulated with five process corners at 27℃ and 90℃. Simulation results demonstrate that the proposed integrated circuit is immune to noise and achieves skipping cycle control when switching mode power supply （SMPS） works with low load or without load.展开更多
The control strategy is firstly the first braking power according to the fuzzy control algorithm, considering the speed, the battery SOC and the battery maximum charging power limit to obtain the maximum braking speed...The control strategy is firstly the first braking power according to the fuzzy control algorithm, considering the speed, the battery SOC and the battery maximum charging power limit to obtain the maximum braking speed, thus the secondary distribution of the hydraulic braking torque. Then the brake control strategy can reduce the impact of the EV braking mode conversion process, and meet the braking demand and brake safety, which proves the effectiveness of the control strategy. In order to ensure the braking stability of the vehicle and further improve the energy utilization rate of electric vehicles, the vehicle speed refueling controller, battery charging state and braking force are used as the energy variables, and the braking force distribution coefficient is taken as the output variable. The braking power distribution coefficient is recommended, considering the stability requirements of the engine, battery, and braking system, to distribute mechanical braking and engine regeneration to the front and rear axles of the machine. Simulation of the developed regenerative braking strategy is analyzed and incorporated into the AVL cruise park model. The results show that this strategy improves braking stability and comfort over the classical ECE curve control strategy, increasing FTP75 by 17.22% compared to the classical ECE curve control strategy展开更多
An experimental analysis of the slug-induced vibration(SIV)of a flexible catenary riser with an aspect ratio of 130 is reported in this work.The vibration responses and internal slug flow details at different gas-liqu...An experimental analysis of the slug-induced vibration(SIV)of a flexible catenary riser with an aspect ratio of 130 is reported in this work.The vibration responses and internal slug flow details at different gas-liquid ratios(Q_(g)/Q_(l))and mixture velocities(vm)are non-intrusively and simultaneously captured by high-speed cameras.Both the in-plane and out-of-plane responses of the catenary riser are excited in all considered cases.The slug flow characteristics,including translational velocities,slug lengths,recurrence frequencies,and pressure variations,are analyzed and dis-cussed,as are the dynamic responses of the riser in terms of the amplitudes,space-varying frequency,and modal weight.The dominant modal response based on the root-mean-square amplitude profiles does not match that based on the dominant frequency.Three mode switching types are identified based on the RMS amplitude profiles and the dominant frequency.When vm is small,no mode switching(NMS)is observed in either the in-plane or out-of-plane responses.For mode switching I(MS I),the switching between the first and second modes in the in-plane response is induced by slug flow with different recurrence frequencies in cases of large Q_(g)/Q_(l).However,there is no mode switching in the out-of-plane response.The switching between the first and third modes for the in-plane response and the second and fourth modes for the out-of-plane response(MS II)occurs in cases of relatively high vm and low Q_(g)/Q_(l).展开更多
To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of...To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.展开更多
This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic ther...This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic thermoacoustic mode.The swirler as an origin of the swirling flow is also the source of the flow disturbance,which has effects on the flame response.The location of the swirler is varied in the experiment to study the effect on combustion instabilities and flame transfer functions.A low order model is built to analyze the thermoacoustic instabilities of the combustion system.The experimental results show that the ITA switches from an unstable state to a stable state as the swirl mixing distance changes with an increment of 15 mm;while the instability of the quarter-wave mode is not varied.The measured Flame Transfer Functions(FTFs)show that the gain curves of the frequency-dependent FTFs seem to be stretched or compressed with the modulation of the swirler position,which has effects on frequencies and instabilities of thermoacoustic modes.With the low order model,the effects of flame response on combustion instabilities are analyzed and the flame dominant nature of the ITA mode is confirmed.展开更多
The chattering characteristic of sliding mode control isanalyzed when it is applied in distributed control systems （DCSs）.For a DCS with random time delay and packet dropout, a discreteswitching system model with ti...The chattering characteristic of sliding mode control isanalyzed when it is applied in distributed control systems （DCSs）.For a DCS with random time delay and packet dropout, a discreteswitching system model with time varying sampling period isconstructed based on the time delay system method. The reachinglaw based sliding mode controller is applied in the proposedsystem. The exponential stability condition in the form of linearmatrix inequality is figured out based on the multi-Lyaponov functionmethod. Then, the chattering characteristic is analyzed for theswitching system, and a chattering region related with time varyingsampling period and external disturbance is proposed. Finally, numericalexamples are given to illustrate the validity of the analysisresult.展开更多
A power train dynamics model of a coaxial parallel hybrid electric vehicle （HEV） was built for different clutch operating states. With the state vector constituted by the motor rotation speed and the clutch transmit...A power train dynamics model of a coaxial parallel hybrid electric vehicle （HEV） was built for different clutch operating states. With the state vector constituted by the motor rotation speed and the clutch transmitting torque at two successive time steps, a discrete state space model for estimating the clutch transmitting torque was built, and the Kalman filtering algorithm was used to estimate the clutch transmitting torque. The Matlab/Simulink was employed to simulate the clutch transmitting torque for two mode-switch processes. Estimation errors were analyzed through compa- ring the estimated and simulated values of the clutch torque. Impact of the noise covariance and the sample time on clutch torque estimation errors were explored. The results show that the developed estimation method can be used to estimate the clutch transmitting torque for HEV with good accura- cy. The results are useful for torque direct control of automatic diaphragm clutches.展开更多
In order to realize the modular design of the microgrid,this paper proposed a new modular topology for the AC-DC mixed microgrid.In that topology,the AC microgrid unit and the DC microgrid unit were packaged together ...In order to realize the modular design of the microgrid,this paper proposed a new modular topology for the AC-DC mixed microgrid.In that topology,the AC microgrid unit and the DC microgrid unit were packaged together by the back-to-back converter.The battery-supercapacitor hybrid energy storage system was connected to the DC bus of back-to-back converter.By the reasonable design on the battery-supercapacitor hybrid system,the energy storage system could supply the rapid power and energy support for the microgrid spontaneously.The mathematical model and the control algorithm of that microgrid topology were studied.By the simulation analysis,it can be concluded that AC-DC mixed modular microgrid topology could operate steadily on both the grid-connected mode and the isolated mode.Furthermore,we can conclude by the simulation that the designed modular microgrid could operate uninterrupted when the microgrid topology switched from the grid-connected mode to the isolated mode.The seamless switching became the natural property for the modular microgrid.As a result,the modular microgrid topology can be considered as a usual power/load module to realize the friendly power interaction with the power grid.展开更多
Multi-frame coding is supported by the emerging H.264. It is important for the enhancement of both coding efficiency and error robustness. In this paper, error resilient schemes for H.264 based on multi-frame were inv...Multi-frame coding is supported by the emerging H.264. It is important for the enhancement of both coding efficiency and error robustness. In this paper, error resilient schemes for H.264 based on multi-frame were investigated. Error robust H.264 video transmission schemes were introduced for the applications with and without a feedback channel. The experimental results demonstrate the effectiveness of the proposed schemes.展开更多
At present,solar thermal power generation is in the demonstration stage,and the large-scale production is affected by many factors.In view of the characteristics of different operating modes of photothermal power gene...At present,solar thermal power generation is in the demonstration stage,and the large-scale production is affected by many factors.In view of the characteristics of different operating modes of photothermal power generation,it is analyzed that the turbine needs to be started and stopped frequently due to different operating modes,which will lead to the instability of the output energy and the reduction of power generation efficiency.In this paper,the dynamic equation of energy conversion process is established by using the law of conservation of energy and conservation of mass.Combined with the logic switching criterion of the system,the system model was established by using the extended differential Petri net,and the validity and accuracy of the model were verified.Through the Petri net model of the system,the system’s working mode switching and power generation situation are analyzed due to the difference of direct normal irradiation intensity(DNI).Finally,the accuracy of the model is proved by comparing it with experimental data of the photovoltaic and thermal demonstration projects that have been connected to the grid.展开更多
Multiantenna technology can be implemented in several modes.These modes have varying characteristics and are used in different scenarios.This paper introduces Beamforming(BF),Cyclic Delay Diversity(CDD),Spatial Divers...Multiantenna technology can be implemented in several modes.These modes have varying characteristics and are used in different scenarios.This paper introduces Beamforming(BF),Cyclic Delay Diversity(CDD),Spatial Diversity(SD),Spatial Multiplexing(SM),and other multiantenna technologies.It also analyzes various technical features and their application scenarios.An adaptive multiantenna switching algorithm is proposed that chooses a suitable mode for sending data according to the scenario or wireless channel conditions.This switching algorithm improves multiantenna technology and enhances the quality of wireless network communications.展开更多
Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact ...Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact on both voltage and frequency. This paper presents the opportunity for monitoring the distributed electrical energy by means of a system that monitors, controls, and provides a breakpoint based on high or low voltage and frequency tripping mechanism that avoids any damage to the load. The designed system comprised a switch mode power supply (SMPS), a direct digital synthesizer (DDS), and PIC16F876A microcontroller techniques for stable voltage and frequency outputs. Proteus design suite version 8.11 software and Benchcope SDS1102CN were used for modeling and simulation. The hardware prototype was implemented at a telecom cell site for data capturing and analysis. Test results showed that the implementation of the prototype provided stable and constant outputs of 222 V/50 Hz and 112 V/60 Hz which constituted 99% and 99.8% efficiency for voltage and frequency performance respectively. The paper also discusses different technologies that can be adopted by the system to mitigate voltage and frequency effects on customer appliances.展开更多
Dissipative Rydberg gases are an outstanding platform for the investigation of many-body open systems.Despite the wealth of existing studies,the non-equilibrium dynamics of dissipative Rydberg gases has rarely been ex...Dissipative Rydberg gases are an outstanding platform for the investigation of many-body open systems.Despite the wealth of existing studies,the non-equilibrium dynamics of dissipative Rydberg gases has rarely been examined or harnessed through the lens of non-Hermitian physics,which is intrinsic to open systems.Here we report the experimental observation of chiral switching between many-body steady states in a dissipative thermal Rydberg vapor,which is underlain by an exceptional structure in the Liouvillian eigenspectrum of the system.Similar to typical chiral state transfer in non-Hermitian systems,as the parameters are adiabatically varied around a closed contour,depending on the chirality of the parameter modulation,the Rydberg vapor can change between two collective steady states with distinct Rydberg excitations and optical transmissions.Adopting a mean-field description,we reveal that both the existence of the bistable steady states and chiral dynamics derive from the Liouvillian exceptional structure,where two exceptional lines merge at a higher-order exceptional point.Such a non-Hermitian perspective of the dissipative Rydberg gas not only provides a new paradigm for chiral mode switching through many-body parameters,as we demonstrate experimentally,but also paves the way for devising novel applications based on the unique features of non-Hermitian physics.展开更多
Due to the advantages such as low line cost,low transmission loss,and high power supply reliability,DC distribution networks have become the main development trend for future distribution networks.In this paper,a typi...Due to the advantages such as low line cost,low transmission loss,and high power supply reliability,DC distribution networks have become the main development trend for future distribution networks.In this paper,a typical DC distribution network with multiple voltage levels is considered as a research object.It is proposed that the interface converters between DC buses with different voltage levels be implemented through the series-parallel combination of full-bridge LLC resonant converters.To realize the decentralized self-discipline control of DC voltage under various working conditions,different slack buses are prepared according to the voltage ranges of the DC buses,and the voltage regulation modes of the DC distribution network are divided into main voltage regulation mode,backup voltage regulation mode,and off-grid voltage droop regulation mode.By introducing a voltage coefficient related to DC voltage deviation as a basis for mode switching,the voltage fluctuations caused by slow switching between control modes in the method of traditional voltage margin control is reduced,facilitating fast and smooth switching between different voltage regulation modes.Finally,a simulation model for DC distribution networks is constructed utilizing MATLAB/Simulink.Simulation results verify the effectiveness and feasibility of the proposed voltage regulation modes and switching methods for DC distribution networks.Finally,an experimental platform is also constructed to verify the feasibility of the mode switching method proposed in this paper.展开更多
Industrial parks(IPs)play a crucial role in facilitating economic efficiency and comprehensive energy utilization in the industrial age.At the same time,multi-energy coupling and management of various types of energy ...Industrial parks(IPs)play a crucial role in facilitating economic efficiency and comprehensive energy utilization in the industrial age.At the same time,multi-energy coupling and management of various types of energy in IP have become serious challenges.In this paper,combined heat and power unit(CHP)model considering operation mode switching characteristics is formulated by exploring its internal composition to improve output flexibility of the energy supply side.Then,heat and electricity integrated energy system(HE-IES)optimal dispatch and pricing model are established,taking electricity and heat demand response strategy and steam thermal inertia property into account.Based on the above models,a mixed-integer bilinear programming framework is designed to coordinate the day-ahead operation and pricing strategy of the HE-IES in the IP.The scenario study is carried out on a practical industrial park in Southern China.Numerical results indicate the proposed mechanism can effectively improve IP’s energy utilization and economic efficiency.展开更多
Electric-hydraulic hybrid power steering(E-HHPS)system,a novel device with multiple modes for commercial electric vehicles,is designed to realize both superior steering feel and high energy efficiency.However,inconsis...Electric-hydraulic hybrid power steering(E-HHPS)system,a novel device with multiple modes for commercial electric vehicles,is designed to realize both superior steering feel and high energy efficiency.However,inconsistent steering perfor-mance occurs in the mode-switching process due to different dynamic characteristics of electric and hydraulic components,which even threatens driving safety.In this paper,mode-switching strategy and dynamic compensation control method are proposed for the E-HHPS system to eliminate the inconsistency of steering feel,which comprehensively considers ideal assistance characteristics and energy consumption of the system.Then,the influence of disturbances on system stability is analyzed,and H_(∞)robust controller is employed to guarantee system robustness and stability.The experimental results dem-onstrate that the proposed strategy can provide a steering system with natural steering feel without apparent inconsistency and effectively minimize energy consumption.展开更多
基金supported by the Chinese Civil Aircraft Project(No.MJ-2017-S49).
文摘With the advancement of more electric aircraft(MEA)technology,the application of electro-hydrostatic actuators(EHAs)in aircraft actuation systems has become increasingly prevalent.This paper focuses on the modeling and mode switching analysis of EHA used in the primary flight control actuation systems of large aircraft,addressing the challenges associated with mode switching.First,we analyze the functional architecture and operational characteristics of multi-mode EHA,and sumarize the operating modes and implementation methods.Based on the EHA system architecture,we then develop a theoretical mathematical model and a simulation model.Using the simulation model,we analyze the performance of the EHA during normal operation.Finally,the performance of the EHA during mode switching under various functional switching scenarios is investigated.The results indicate that the EHA meets the performance requirements in terms of accuracy,bandwidth,and load capacity.Additionally,the hydraulic cylinder operates smoothly during the EHA mode switching,and the response time for switching between different modes is less than the specified threshold.These findings validate the system performance of multi-mode EHA,which helps to improve the reliability of EHA and the safety of aircraft flight control systems.
基金Supported by the National Natural Science Foundation of China(52172324)Key Research and Development Plan of Shaanxi Province(2021GY-285,2021SF-483)+1 种基金Science and Technology Project of Shaanxi Provincial Department of Transport(21-20K,20-38T)Fundamental Research Funds for the Central Universities,CHD(300102323501)。
文摘In order to enhance the safety of autonomous driving vehicles,this work focuses on the issue of automatic-to-manual mode transition in the column electric power steering(C-EPS)system.First,we utilized an extended state observer to estimate the driver's steering torque and designed a steering mode transition unit.Second,we validated the mode switching function through an experimental platform.The results indicated that when using the extended state observer for torque estimation,the steering wheel angle and lower input angle errors were approximately±0.5%.The input and observed torque curves were closely aligned,demonstrating excellent tracking capability of the system.In addition,by adopting a steering mode conversion unit,the switch from autonomous control to manual control has been obtained,achieving a smooth and minimal change in steering wheel angle without significant bumps.The experimental results demonstrate that the designed mode switching strategy has the advantages of speed and smoothness,and has strong practical value.
基金This work was supported in part by the Natural Science Foundation of Henan Province,and the specific grant number is 232300420301the initial of author is P.L.,the URL to the sponsors’websites is https://kjt.henan.gov.cn/(accessed on 09 February 2025)And this work was also supported in part by the Fundamental Research Funds for the Universities of Henan Province,and the specific grant number is NSFRF220425,the initial of author is P.L.,the URL to sponsors websites is http://app.hnkjt.gov.cn/web/index.do(accessed on 09 February 2025).
文摘The photovoltaic(PV)output process is inherently complex,often disrupted by a multitude of meteoro-logical factors,while conventional detection methods at PV power stations prove inadequate,compromising prediction accuracy.To address this challenge,this paper introduces a power prediction method that leverages modal switching(MS),weight factor adjustment(WFA),and parallel long short-term memory(PALSTM).Initially,historical PV power station data is categorized into distinct modes based on global horizontal irradiance and converted solar angles.Correlation analysis is then employed to evaluate the impact of various meteorological factors on PV power,selecting those with strong correlations for each specific mode.Subsequently,the weights of meteorological parameters are optimized and adjusted,and a PALSTM neural network is constructed,with its parallel modal parameters refined through training.Depending on the prediction time and input data mode characteristics,the appropriate mode channel is selected to forecast PV power station generation.Ultimately,the feasibility of this method is validated through an illustrative analysis of measured data from an Australian PV power station.Comparative test results underscore the method’s advantages,particularly in scenarios where existing detection methods are lacking and meteorological factors frequently fluctuate,demonstrating its superior prediction accuracy and stability.
基金Supported by Doctoral Fund of Ministry of Education of China(20101101110012)the National Natural Science Foundationof China(51175040)
文摘Based on analyzing the structure and working principle on electric vehicles （EVs） with dual motors coupled by planetarY gears, the control strategy of mode switching was proposed. The power interruption problem on EVs with automatic mechanical transmission （AMT） shifting was resolved. Based on the speed-torque characteristics of the planetary gears and the principle of the auxiliary motor＇ s zero speed braking, control features of mode switching were introduced. The mode shifting between the main motor mode and dual motors coupled driving were studied. Matlab/Simulink was adopted as a platform to develop the simulation model of EVs with dual motors drive system and 3 gears AMT. Simulation results demonstrated that the power interruption of dual motors drive system was solved during mode switching. The power requirements of EVs were satisfied, too.
文摘This paper explores and proposes a design solution of an integrated skip cycle mode （SCM） control circuit with a simple structure. The design is simulated and implemented with XD10H-1.0μm modular DIMOS 650 V process. In order to meet the requirement of a wide temperature range and high yields of products, the schematic extracted from the layout is simulated with five process corners at 27℃ and 90℃. Simulation results demonstrate that the proposed integrated circuit is immune to noise and achieves skipping cycle control when switching mode power supply （SMPS） works with low load or without load.
文摘The control strategy is firstly the first braking power according to the fuzzy control algorithm, considering the speed, the battery SOC and the battery maximum charging power limit to obtain the maximum braking speed, thus the secondary distribution of the hydraulic braking torque. Then the brake control strategy can reduce the impact of the EV braking mode conversion process, and meet the braking demand and brake safety, which proves the effectiveness of the control strategy. In order to ensure the braking stability of the vehicle and further improve the energy utilization rate of electric vehicles, the vehicle speed refueling controller, battery charging state and braking force are used as the energy variables, and the braking force distribution coefficient is taken as the output variable. The braking power distribution coefficient is recommended, considering the stability requirements of the engine, battery, and braking system, to distribute mechanical braking and engine regeneration to the front and rear axles of the machine. Simulation of the developed regenerative braking strategy is analyzed and incorporated into the AVL cruise park model. The results show that this strategy improves braking stability and comfort over the classical ECE curve control strategy, increasing FTP75 by 17.22% compared to the classical ECE curve control strategy
基金financially supported by the National Natural Science Foundation of China(Grant No.52301338)the Sichuan Science and Technology Program(Grant No.2024NSFSC0968).
文摘An experimental analysis of the slug-induced vibration(SIV)of a flexible catenary riser with an aspect ratio of 130 is reported in this work.The vibration responses and internal slug flow details at different gas-liquid ratios(Q_(g)/Q_(l))and mixture velocities(vm)are non-intrusively and simultaneously captured by high-speed cameras.Both the in-plane and out-of-plane responses of the catenary riser are excited in all considered cases.The slug flow characteristics,including translational velocities,slug lengths,recurrence frequencies,and pressure variations,are analyzed and dis-cussed,as are the dynamic responses of the riser in terms of the amplitudes,space-varying frequency,and modal weight.The dominant modal response based on the root-mean-square amplitude profiles does not match that based on the dominant frequency.Three mode switching types are identified based on the RMS amplitude profiles and the dominant frequency.When vm is small,no mode switching(NMS)is observed in either the in-plane or out-of-plane responses.For mode switching I(MS I),the switching between the first and second modes in the in-plane response is induced by slug flow with different recurrence frequencies in cases of large Q_(g)/Q_(l).However,there is no mode switching in the out-of-plane response.The switching between the first and third modes for the in-plane response and the second and fourth modes for the out-of-plane response(MS II)occurs in cases of relatively high vm and low Q_(g)/Q_(l).
基金Supported by National Natural Science Foundation of China (Grant Nos. 52375003, 52205006)National Key R&D Program of China (Grant No. 2019YFB1309600)。
文摘To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.
基金supported the National Natural Science Foundation of China(Nos.51676126 and 51776191)。
文摘This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic thermoacoustic mode.The swirler as an origin of the swirling flow is also the source of the flow disturbance,which has effects on the flame response.The location of the swirler is varied in the experiment to study the effect on combustion instabilities and flame transfer functions.A low order model is built to analyze the thermoacoustic instabilities of the combustion system.The experimental results show that the ITA switches from an unstable state to a stable state as the swirl mixing distance changes with an increment of 15 mm;while the instability of the quarter-wave mode is not varied.The measured Flame Transfer Functions(FTFs)show that the gain curves of the frequency-dependent FTFs seem to be stretched or compressed with the modulation of the swirler position,which has effects on frequencies and instabilities of thermoacoustic modes.With the low order model,the effects of flame response on combustion instabilities are analyzed and the flame dominant nature of the ITA mode is confirmed.
基金supported by the National Natural Science Fundation of China(5147618751506221)+1 种基金the Natural Science Basic Research Plan in Shaanxi Province of China(2015JQ51792015JM5207)
文摘The chattering characteristic of sliding mode control isanalyzed when it is applied in distributed control systems （DCSs）.For a DCS with random time delay and packet dropout, a discreteswitching system model with time varying sampling period isconstructed based on the time delay system method. The reachinglaw based sliding mode controller is applied in the proposedsystem. The exponential stability condition in the form of linearmatrix inequality is figured out based on the multi-Lyaponov functionmethod. Then, the chattering characteristic is analyzed for theswitching system, and a chattering region related with time varyingsampling period and external disturbance is proposed. Finally, numericalexamples are given to illustrate the validity of the analysisresult.
基金Supported by the National High Technology Research and Development Program of China(863Program)(2012AA111104)
文摘A power train dynamics model of a coaxial parallel hybrid electric vehicle （HEV） was built for different clutch operating states. With the state vector constituted by the motor rotation speed and the clutch transmitting torque at two successive time steps, a discrete state space model for estimating the clutch transmitting torque was built, and the Kalman filtering algorithm was used to estimate the clutch transmitting torque. The Matlab/Simulink was employed to simulate the clutch transmitting torque for two mode-switch processes. Estimation errors were analyzed through compa- ring the estimated and simulated values of the clutch torque. Impact of the noise covariance and the sample time on clutch torque estimation errors were explored. The results show that the developed estimation method can be used to estimate the clutch transmitting torque for HEV with good accura- cy. The results are useful for torque direct control of automatic diaphragm clutches.
文摘In order to realize the modular design of the microgrid,this paper proposed a new modular topology for the AC-DC mixed microgrid.In that topology,the AC microgrid unit and the DC microgrid unit were packaged together by the back-to-back converter.The battery-supercapacitor hybrid energy storage system was connected to the DC bus of back-to-back converter.By the reasonable design on the battery-supercapacitor hybrid system,the energy storage system could supply the rapid power and energy support for the microgrid spontaneously.The mathematical model and the control algorithm of that microgrid topology were studied.By the simulation analysis,it can be concluded that AC-DC mixed modular microgrid topology could operate steadily on both the grid-connected mode and the isolated mode.Furthermore,we can conclude by the simulation that the designed modular microgrid could operate uninterrupted when the microgrid topology switched from the grid-connected mode to the isolated mode.The seamless switching became the natural property for the modular microgrid.As a result,the modular microgrid topology can be considered as a usual power/load module to realize the friendly power interaction with the power grid.
文摘Multi-frame coding is supported by the emerging H.264. It is important for the enhancement of both coding efficiency and error robustness. In this paper, error resilient schemes for H.264 based on multi-frame were investigated. Error robust H.264 video transmission schemes were introduced for the applications with and without a feedback channel. The experimental results demonstrate the effectiveness of the proposed schemes.
基金supported by the Science Technology Project of State Grid Corporation of China(Grant No.52272219000 V)the Major Science and Technology Project of Gansu Province(Grant No.20ZD7GF011).
文摘At present,solar thermal power generation is in the demonstration stage,and the large-scale production is affected by many factors.In view of the characteristics of different operating modes of photothermal power generation,it is analyzed that the turbine needs to be started and stopped frequently due to different operating modes,which will lead to the instability of the output energy and the reduction of power generation efficiency.In this paper,the dynamic equation of energy conversion process is established by using the law of conservation of energy and conservation of mass.Combined with the logic switching criterion of the system,the system model was established by using the extended differential Petri net,and the validity and accuracy of the model were verified.Through the Petri net model of the system,the system’s working mode switching and power generation situation are analyzed due to the difference of direct normal irradiation intensity(DNI).Finally,the accuracy of the model is proved by comparing it with experimental data of the photovoltaic and thermal demonstration projects that have been connected to the grid.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China under Grant No.2009ZX03003
文摘Multiantenna technology can be implemented in several modes.These modes have varying characteristics and are used in different scenarios.This paper introduces Beamforming(BF),Cyclic Delay Diversity(CDD),Spatial Diversity(SD),Spatial Multiplexing(SM),and other multiantenna technologies.It also analyzes various technical features and their application scenarios.An adaptive multiantenna switching algorithm is proposed that chooses a suitable mode for sending data according to the scenario or wireless channel conditions.This switching algorithm improves multiantenna technology and enhances the quality of wireless network communications.
文摘Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact on both voltage and frequency. This paper presents the opportunity for monitoring the distributed electrical energy by means of a system that monitors, controls, and provides a breakpoint based on high or low voltage and frequency tripping mechanism that avoids any damage to the load. The designed system comprised a switch mode power supply (SMPS), a direct digital synthesizer (DDS), and PIC16F876A microcontroller techniques for stable voltage and frequency outputs. Proteus design suite version 8.11 software and Benchcope SDS1102CN were used for modeling and simulation. The hardware prototype was implemented at a telecom cell site for data capturing and analysis. Test results showed that the implementation of the prototype provided stable and constant outputs of 222 V/50 Hz and 112 V/60 Hz which constituted 99% and 99.8% efficiency for voltage and frequency performance respectively. The paper also discusses different technologies that can be adopted by the system to mitigate voltage and frequency effects on customer appliances.
基金supported by the Innovation Program for Quantum Science and Technology(2024ZD0300900)the National Natural Science Foundation of China(12134014,61905234,11974335,12374337,and 12374479)+3 种基金the Key Research Program of Frontier Sciences,CAS(QYZDYSSW-SLHO03)University of Science and Technology of China Research Funds of the Double First-Class Initiative(YD2030002007)the Fundamental Research Funds for the Central Universities(WK2470000035)the Innovation Program for Quantum Science and Technology(2021ZD0301200).
文摘Dissipative Rydberg gases are an outstanding platform for the investigation of many-body open systems.Despite the wealth of existing studies,the non-equilibrium dynamics of dissipative Rydberg gases has rarely been examined or harnessed through the lens of non-Hermitian physics,which is intrinsic to open systems.Here we report the experimental observation of chiral switching between many-body steady states in a dissipative thermal Rydberg vapor,which is underlain by an exceptional structure in the Liouvillian eigenspectrum of the system.Similar to typical chiral state transfer in non-Hermitian systems,as the parameters are adiabatically varied around a closed contour,depending on the chirality of the parameter modulation,the Rydberg vapor can change between two collective steady states with distinct Rydberg excitations and optical transmissions.Adopting a mean-field description,we reveal that both the existence of the bistable steady states and chiral dynamics derive from the Liouvillian exceptional structure,where two exceptional lines merge at a higher-order exceptional point.Such a non-Hermitian perspective of the dissipative Rydberg gas not only provides a new paradigm for chiral mode switching through many-body parameters,as we demonstrate experimentally,but also paves the way for devising novel applications based on the unique features of non-Hermitian physics.
基金supported by Fundamental Research Funds for the Central Universities(No.2019JBM057)。
文摘Due to the advantages such as low line cost,low transmission loss,and high power supply reliability,DC distribution networks have become the main development trend for future distribution networks.In this paper,a typical DC distribution network with multiple voltage levels is considered as a research object.It is proposed that the interface converters between DC buses with different voltage levels be implemented through the series-parallel combination of full-bridge LLC resonant converters.To realize the decentralized self-discipline control of DC voltage under various working conditions,different slack buses are prepared according to the voltage ranges of the DC buses,and the voltage regulation modes of the DC distribution network are divided into main voltage regulation mode,backup voltage regulation mode,and off-grid voltage droop regulation mode.By introducing a voltage coefficient related to DC voltage deviation as a basis for mode switching,the voltage fluctuations caused by slow switching between control modes in the method of traditional voltage margin control is reduced,facilitating fast and smooth switching between different voltage regulation modes.Finally,a simulation model for DC distribution networks is constructed utilizing MATLAB/Simulink.Simulation results verify the effectiveness and feasibility of the proposed voltage regulation modes and switching methods for DC distribution networks.Finally,an experimental platform is also constructed to verify the feasibility of the mode switching method proposed in this paper.
基金supported by the National Natural Science Foundation of China(No.52177077)by the Science and Technology Project of State Grid Jiangsu Electric Power Co.,Ltd.,Grant J20210148.
文摘Industrial parks(IPs)play a crucial role in facilitating economic efficiency and comprehensive energy utilization in the industrial age.At the same time,multi-energy coupling and management of various types of energy in IP have become serious challenges.In this paper,combined heat and power unit(CHP)model considering operation mode switching characteristics is formulated by exploring its internal composition to improve output flexibility of the energy supply side.Then,heat and electricity integrated energy system(HE-IES)optimal dispatch and pricing model are established,taking electricity and heat demand response strategy and steam thermal inertia property into account.Based on the above models,a mixed-integer bilinear programming framework is designed to coordinate the day-ahead operation and pricing strategy of the HE-IES in the IP.The scenario study is carried out on a practical industrial park in Southern China.Numerical results indicate the proposed mechanism can effectively improve IP’s energy utilization and economic efficiency.
基金supported by the Jiangsu Key R&D Plan under Grants BE2022053-3.
文摘Electric-hydraulic hybrid power steering(E-HHPS)system,a novel device with multiple modes for commercial electric vehicles,is designed to realize both superior steering feel and high energy efficiency.However,inconsistent steering perfor-mance occurs in the mode-switching process due to different dynamic characteristics of electric and hydraulic components,which even threatens driving safety.In this paper,mode-switching strategy and dynamic compensation control method are proposed for the E-HHPS system to eliminate the inconsistency of steering feel,which comprehensively considers ideal assistance characteristics and energy consumption of the system.Then,the influence of disturbances on system stability is analyzed,and H_(∞)robust controller is employed to guarantee system robustness and stability.The experimental results dem-onstrate that the proposed strategy can provide a steering system with natural steering feel without apparent inconsistency and effectively minimize energy consumption.
