Intelligent reflecting surface(IRS) is regarded as a promising technology because it can achieve higher passive beamforming gain. In particular, the IRS assisted simultaneous wireless information and power transfer(SW...Intelligent reflecting surface(IRS) is regarded as a promising technology because it can achieve higher passive beamforming gain. In particular, the IRS assisted simultaneous wireless information and power transfer(SWIPT) system can make the information decoding receivers(IDRs) have a higher signal-to-noise ratio(SNR), and the energy harvesting receivers(EHRs) have the guarantee of minimum harvested energy threshold. Motivated by the above,in this paper, we use the power splitting(PS) at the user and introduce artificial noise(AN) into the access point(AP), so that the user in system can harvest energy and decode information simultaneously,further improve the security of user. We jointly optimize the beamforming matrix at AP, the reflection phase shift at IRS and the PS ratio, in order to maximize the user’s achievable secrecy rate, subject to the user’s minimum harvested energy threshold and AP’s transmission power. Due to the introduction of PS ratio, the coupling between variables is increased,and the complexity of the problem is significantly increased. Furthermore, the problem is non-convex, so we propose an efficient algorithm based on Taylor Formula, semi-definite relaxation(SDR) and alternating optimization(AO) to get the solution. Numerical results show that the proposed IRS-SWIPT system with PS and AN achieves significant performance improvement compared with other benchmark scheme.展开更多
As a novel signaling technology,the power splitting receiver(PSR)simultaneously employs both the coherent and non-coherent signal processing.In order to improve its communication performance,an intelligent reflecting ...As a novel signaling technology,the power splitting receiver(PSR)simultaneously employs both the coherent and non-coherent signal processing.In order to improve its communication performance,an intelligent reflecting surface(IRS)is introduced into its signal propagation path.Consequently,an IRSaided PSR is concerned for a point-to-point(P2P)data link,where both the single-antenna and multiantenna deployments on the receiver are discussed.We aim at maximizing the capacity of the concerned P2P data-link by jointly optimizing the passive beamforming of IRS and the splitting ratio of PSR,either in single-antenna or multi-antenna case.However,owing to the coupling of multiple variables,the optimization problems are non-convex and challenging,especially in the later multi-antenna case.The proposed alternating-approximating algorithm(A-A),aided by semi-definite relaxation(SDR)and successive convex approximation(SCA)methods,etc.,successfully overcomes these challenges.We compare the IRS-aided PSR system that optimized by our proposed algorithm to the systems without IRS or PSR,and the systems without joint optimization.The simulation results show that our proposal has a better performance.展开更多
Based on Newton ' s second law,the bend-torsion-shaft coupling nonlinear dynamic model and equations of power split gear transmission system are established.According to the principle of tooth profile modification...Based on Newton ' s second law,the bend-torsion-shaft coupling nonlinear dynamic model and equations of power split gear transmission system are established.According to the principle of tooth profile modification,the tooth profile modification is considered as time-varying gear backlash function acting along the line of action.Then the dynamic functions are solved by using Runge-Kutta numerical method.After analyzing the effect of tooth profile modification quantity( TPMQ) and relative tooth profile modification length( TPML) to the nonlinear dynamic characteristics of power split gear transmission,the following conclusions are drawn:1 The TPMQ of a certain stage transmission affects the vibration of its own stage more significantly than the other stage,and the coupling effect between two stages can be ignored usually in the modification design;2 If the first stage TPMLs are less than 0.3,the influence of the first stage TPMLs to the first stage transmission vibration is much more greatly than the influence of the second stage TPMLs to the first stage transmission vibration,or else both the first and second stage TPMLs affect the first stage transmission vibration largely.The same is true for the second stage TPMLs,and the cutoff value is 0.2;3 The TPMQ affects the vibration of power split gear transmission system more principally than the TPML,and should be top-priority in the modification design.展开更多
In order to identify all the appropriate system schemes for the compound split systems formed primarily with a four-port mechanical power split device, power transmission characteristics of the compound split systems ...In order to identify all the appropriate system schemes for the compound split systems formed primarily with a four-port mechanical power split device, power transmission characteristics of the compound split systems was analyzed. Considering the structural symmetry and according to the different connection arrangement of the four ports, compound split system was classified into four types. Using black-box modeling method, the generalized models of the speed ratio, the torque ratio and the power split ratio were established. Moreover, a semi-invert diagram was used to distin- guish the different schemes in each type. The characteristics of the speed ratio, the torque ratio and the power split ratio in each domain were also analyzed and compared. Through the semi-invert dia- gram, a selection method based on the rated-power speed ranges in different schemes was presented and all suitable compound split systems were identified, which can be used as references for the scheme selection of this kind of continuously variable power split transmission.展开更多
The performance of symbiotic radio(SR)networks can be improved by equipping secondary transmitters(STs)with intelligent reflecting surfaces(IRSs).Since the IRS power consumption is a non-negligible issue for STs,we co...The performance of symbiotic radio(SR)networks can be improved by equipping secondary transmitters(STs)with intelligent reflecting surfaces(IRSs).Since the IRS power consumption is a non-negligible issue for STs,we consider an IRS assisted SR system where the IRS operates under power splitting(PS)mode.We aim at minimizing the IRS power consumption for the ST under the quality of service constraints for both primary and secondary transmissions by optimizing the transmit beamforming,the reflect beamforming and the PS factor.The optimization problem is non-convex.To tackle it,an algorithm is proposed by employing the block coordinate descent,semidefinite relaxation and alternating direction method of multipliers techniques.Simulation results demonstrate the efficiency and effectiveness of the proposed algorithm.展开更多
The deformation compatibility equations and the torque balance equations of star gearing with three branches have been found based on the characteristic that the system composes a closed-loop of power flow. In conside...The deformation compatibility equations and the torque balance equations of star gearing with three branches have been found based on the characteristic that the system composes a closed-loop of power flow. In consideration of the parts manufacturing errors, assembly errors, bearing stiffness and float, the power splitting rate of each star gear and the system were calculated by using the theory of equivalent mesh error. The effects of the errors, float and the bearing stiffness on power splitting were studied. The study provides a useful theoretical guideline for the design of star gearing.展开更多
In order to implement the dynamic characteristic of a dual power-split transmission, a dynamic me- chanics model is built. Firstly, according to the method of theoretical analysis of the tooth contact analysis （TCA）...In order to implement the dynamic characteristic of a dual power-split transmission, a dynamic me- chanics model is built. Firstly, according to the method of theoretical analysis of the tooth contact analysis （TCA） and loaded tooth contact analysis （LTCA）, the actual meshing process of each gear pairs is simulated, and the time-varying mesh stiffness excitations are obtained, which can improve the numerical precision. Second- ly, by using the lumped mass method, the bending-torsional coupling three dimensional dynamic model of the dual power-split transmission is established, and the identical dimensionless equations are deduced by elimina- ting the effect of rigid displacement and the method of dimensional normalization. Finally, by the method of the fourth order Runge-Kutta algorithm with variable step lengths, the responses of this system in a frequency domain and time domain are obtained, and the dynamic load change characteristics of each gear pairs are analyzed. The results show that the establishment, solution and analysis of the system dynamics model could provide a basis for the dynamic design, and have an important significance for the dynamic efficiency analysis and dynamic perform- ance optimization design of the dual power-split transmission.展开更多
Continuous transient impact(CTI)frequently occurs in power split(PS)hybrid powertrain system when the mode transition torque crossing zero,which affects overall vehicle ride comfort.To study the CTI mechanism,a transi...Continuous transient impact(CTI)frequently occurs in power split(PS)hybrid powertrain system when the mode transition torque crossing zero,which affects overall vehicle ride comfort.To study the CTI mechanism,a transient torsional vibration(TTV)coupling model of a hybrid powertrain test system is established based on the test bench with double feedforward correction load emulation compensation control,and realize the CTI performance prediction along the power transfer path.Firstly,the time-domain and frequency-domain characteristics of CTI during the mode transition process(MTP)test are introduced.Secondly,the external excitation model including bench load,engine resistance torque and motor torque ripple,and the internal excitation model including the torsional vibration of planetary coupling(PC)and two stage reducer are established.Then,the MTP coordinated control method of power split hybrid powertrain test system are introduced,and the gear torque zero crossing model which considering time-varying stiffness,damping and gear backlash is integrated into the TTV model.Finally,the CTI mechanism is simulated and analyzed.The results show that the front planet gear of Ravigneaux-PC is the main source of high-frequency gear knocking.Moreover,the frequent torque crossing zero at the dedicated hybrid transmission(DHT)power output end after the torque coordinated control of each power source is the main cause of continuous mesh impact during MTP,and the coupling effect with the gear backlash intensifies the CTI of DHT output end at frequency band 100–200 Hz,and the CTI can reduce the overall efficiency of PS-DHT system and vehicle comfort.The research results are useful for the development of CTI suppression optimization algorithm.展开更多
For the simultaneous wireless information and power transfer(SWIPT), the full-duplex MIMO system can achieve simultaneous transmission of information and energy more efficiently than the half-duplex. Based on the mean...For the simultaneous wireless information and power transfer(SWIPT), the full-duplex MIMO system can achieve simultaneous transmission of information and energy more efficiently than the half-duplex. Based on the mean-square-error(MSE) criterion, the optimization problem of joint transceiver design with transmitting power constraint and energy harvesting constraint is formulated. Next, by semidefinite relaxation(SDR) and randomization method, the SDRbased scheme is proposed. In order to reduce the complexity, the closed-form scheme is presented with some simplified measures. Robust beamforming is then studied considering the practical condition. The simulation results such as MSE versus signal-noise-ratio(SNR), MSE versus the iteration number, well prove the performance of the proposed schemes for the system model.展开更多
In this paper, we propose the decode-and-forward(DF) based bidirectional wireless information and power transfer(BWIPT) in two-hop relay systems, where the bidirectional relay can decode and forward information from t...In this paper, we propose the decode-and-forward(DF) based bidirectional wireless information and power transfer(BWIPT) in two-hop relay systems, where the bidirectional relay can decode and forward information from the user to the access point(AP), and assist the wireless power transfer from the AP to the user. To maximize the information rate from the user to the AP, we derive the closed form expression of the optimal power splitting(PS) factor, and the time allocation scheme to obtain the optimal time switching(TS) factor. Simulation results show that for both PS and TS protocols, the proposed DF based bidirectional relay systems can improve the information rate as compared with the amplify-and-forward(AF) based bidirectional relay systems.展开更多
Regarding mobile machinery, particularly agricultural tractors, there is an ongoing competition for the most suitable technology to achieve optimum functionality with maximum efficiency. In this competition, the effic...Regarding mobile machinery, particularly agricultural tractors, there is an ongoing competition for the most suitable technology to achieve optimum functionality with maximum efficiency. In this competition, the efficiency of electric series-hybrid powertrains （ESHPs） is often depicted as worse than the efficiency of mechanical-hydraulic power-split powertrains （MHPSPs）. On closer inspection of these statements, however, systematic errors, such as unequal balance limits, neglected size effects and nonlinearities, non-observance of recent technical developments and standards, or erroneous application of research results regarding MHPSPs on ESHPs are often evident. For verification （and under avoidance of the systematic errors mentioned above）, the losses of an ESHP of 150 kW power are for example calculated and compared with the losses of a typical MHPSP of the same power. The comparison of the losses shows that the ESHP clearly exceeds the efficiency of the comparative MHPSP in the main working range and that there is still potential for improvement.展开更多
基金supported by the National Natural Science Foundation of China (No. 61971190)the Fundamental Research Funds for the Central Universities (No. 2019 MS089)+1 种基金the Hebei Province Natural Science Foundation (No. F2016502062)the Beijing Natural Science Foundation (No. 4164101)。
文摘Intelligent reflecting surface(IRS) is regarded as a promising technology because it can achieve higher passive beamforming gain. In particular, the IRS assisted simultaneous wireless information and power transfer(SWIPT) system can make the information decoding receivers(IDRs) have a higher signal-to-noise ratio(SNR), and the energy harvesting receivers(EHRs) have the guarantee of minimum harvested energy threshold. Motivated by the above,in this paper, we use the power splitting(PS) at the user and introduce artificial noise(AN) into the access point(AP), so that the user in system can harvest energy and decode information simultaneously,further improve the security of user. We jointly optimize the beamforming matrix at AP, the reflection phase shift at IRS and the PS ratio, in order to maximize the user’s achievable secrecy rate, subject to the user’s minimum harvested energy threshold and AP’s transmission power. Due to the introduction of PS ratio, the coupling between variables is increased,and the complexity of the problem is significantly increased. Furthermore, the problem is non-convex, so we propose an efficient algorithm based on Taylor Formula, semi-definite relaxation(SDR) and alternating optimization(AO) to get the solution. Numerical results show that the proposed IRS-SWIPT system with PS and AN achieves significant performance improvement compared with other benchmark scheme.
基金supported by National Key R&D Program of China with Grant number 2019YFB1803400in part by Sichuan Science and Technology Program under Grant 2024NSFSC0472。
文摘As a novel signaling technology,the power splitting receiver(PSR)simultaneously employs both the coherent and non-coherent signal processing.In order to improve its communication performance,an intelligent reflecting surface(IRS)is introduced into its signal propagation path.Consequently,an IRSaided PSR is concerned for a point-to-point(P2P)data link,where both the single-antenna and multiantenna deployments on the receiver are discussed.We aim at maximizing the capacity of the concerned P2P data-link by jointly optimizing the passive beamforming of IRS and the splitting ratio of PSR,either in single-antenna or multi-antenna case.However,owing to the coupling of multiple variables,the optimization problems are non-convex and challenging,especially in the later multi-antenna case.The proposed alternating-approximating algorithm(A-A),aided by semi-definite relaxation(SDR)and successive convex approximation(SCA)methods,etc.,successfully overcomes these challenges.We compare the IRS-aided PSR system that optimized by our proposed algorithm to the systems without IRS or PSR,and the systems without joint optimization.The simulation results show that our proposal has a better performance.
基金Sponsored by the National Natural Science Foundation of China(Grant No.2009AA04Z404)
文摘Based on Newton ' s second law,the bend-torsion-shaft coupling nonlinear dynamic model and equations of power split gear transmission system are established.According to the principle of tooth profile modification,the tooth profile modification is considered as time-varying gear backlash function acting along the line of action.Then the dynamic functions are solved by using Runge-Kutta numerical method.After analyzing the effect of tooth profile modification quantity( TPMQ) and relative tooth profile modification length( TPML) to the nonlinear dynamic characteristics of power split gear transmission,the following conclusions are drawn:1 The TPMQ of a certain stage transmission affects the vibration of its own stage more significantly than the other stage,and the coupling effect between two stages can be ignored usually in the modification design;2 If the first stage TPMLs are less than 0.3,the influence of the first stage TPMLs to the first stage transmission vibration is much more greatly than the influence of the second stage TPMLs to the first stage transmission vibration,or else both the first and second stage TPMLs affect the first stage transmission vibration largely.The same is true for the second stage TPMLs,and the cutoff value is 0.2;3 The TPMQ affects the vibration of power split gear transmission system more principally than the TPML,and should be top-priority in the modification design.
基金Supported by the Ministerial Level Advanced Research Foudation (111044)
文摘In order to identify all the appropriate system schemes for the compound split systems formed primarily with a four-port mechanical power split device, power transmission characteristics of the compound split systems was analyzed. Considering the structural symmetry and according to the different connection arrangement of the four ports, compound split system was classified into four types. Using black-box modeling method, the generalized models of the speed ratio, the torque ratio and the power split ratio were established. Moreover, a semi-invert diagram was used to distin- guish the different schemes in each type. The characteristics of the speed ratio, the torque ratio and the power split ratio in each domain were also analyzed and compared. Through the semi-invert dia- gram, a selection method based on the rated-power speed ranges in different schemes was presented and all suitable compound split systems were identified, which can be used as references for the scheme selection of this kind of continuously variable power split transmission.
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-TP-20-106A1)。
文摘The performance of symbiotic radio(SR)networks can be improved by equipping secondary transmitters(STs)with intelligent reflecting surfaces(IRSs).Since the IRS power consumption is a non-negligible issue for STs,we consider an IRS assisted SR system where the IRS operates under power splitting(PS)mode.We aim at minimizing the IRS power consumption for the ST under the quality of service constraints for both primary and secondary transmissions by optimizing the transmit beamforming,the reflect beamforming and the PS factor.The optimization problem is non-convex.To tackle it,an algorithm is proposed by employing the block coordinate descent,semidefinite relaxation and alternating direction method of multipliers techniques.Simulation results demonstrate the efficiency and effectiveness of the proposed algorithm.
基金supported by the Natural Science Foundation of China (51175423)
文摘The deformation compatibility equations and the torque balance equations of star gearing with three branches have been found based on the characteristic that the system composes a closed-loop of power flow. In consideration of the parts manufacturing errors, assembly errors, bearing stiffness and float, the power splitting rate of each star gear and the system were calculated by using the theory of equivalent mesh error. The effects of the errors, float and the bearing stiffness on power splitting were studied. The study provides a useful theoretical guideline for the design of star gearing.
基金supported by the Natural Science Foundation of China under Grant No.51175423
文摘In order to implement the dynamic characteristic of a dual power-split transmission, a dynamic me- chanics model is built. Firstly, according to the method of theoretical analysis of the tooth contact analysis （TCA） and loaded tooth contact analysis （LTCA）, the actual meshing process of each gear pairs is simulated, and the time-varying mesh stiffness excitations are obtained, which can improve the numerical precision. Second- ly, by using the lumped mass method, the bending-torsional coupling three dimensional dynamic model of the dual power-split transmission is established, and the identical dimensionless equations are deduced by elimina- ting the effect of rigid displacement and the method of dimensional normalization. Finally, by the method of the fourth order Runge-Kutta algorithm with variable step lengths, the responses of this system in a frequency domain and time domain are obtained, and the dynamic load change characteristics of each gear pairs are analyzed. The results show that the establishment, solution and analysis of the system dynamics model could provide a basis for the dynamic design, and have an important significance for the dynamic efficiency analysis and dynamic perform- ance optimization design of the dual power-split transmission.
基金funded by National Natural Science Foundation of China,under grand number 51675381Science and Technology Innovation Plan Of Shanghai Science and Technology Commission under grand number 21DZ1209700.
文摘Continuous transient impact(CTI)frequently occurs in power split(PS)hybrid powertrain system when the mode transition torque crossing zero,which affects overall vehicle ride comfort.To study the CTI mechanism,a transient torsional vibration(TTV)coupling model of a hybrid powertrain test system is established based on the test bench with double feedforward correction load emulation compensation control,and realize the CTI performance prediction along the power transfer path.Firstly,the time-domain and frequency-domain characteristics of CTI during the mode transition process(MTP)test are introduced.Secondly,the external excitation model including bench load,engine resistance torque and motor torque ripple,and the internal excitation model including the torsional vibration of planetary coupling(PC)and two stage reducer are established.Then,the MTP coordinated control method of power split hybrid powertrain test system are introduced,and the gear torque zero crossing model which considering time-varying stiffness,damping and gear backlash is integrated into the TTV model.Finally,the CTI mechanism is simulated and analyzed.The results show that the front planet gear of Ravigneaux-PC is the main source of high-frequency gear knocking.Moreover,the frequent torque crossing zero at the dedicated hybrid transmission(DHT)power output end after the torque coordinated control of each power source is the main cause of continuous mesh impact during MTP,and the coupling effect with the gear backlash intensifies the CTI of DHT output end at frequency band 100–200 Hz,and the CTI can reduce the overall efficiency of PS-DHT system and vehicle comfort.The research results are useful for the development of CTI suppression optimization algorithm.
基金supported by the National Great Science Specif ic Project (Grants No. 2014ZX03002002-004)National Natural Science Foundation of China (Grants No. NSFC-61471067)
文摘For the simultaneous wireless information and power transfer(SWIPT), the full-duplex MIMO system can achieve simultaneous transmission of information and energy more efficiently than the half-duplex. Based on the mean-square-error(MSE) criterion, the optimization problem of joint transceiver design with transmitting power constraint and energy harvesting constraint is formulated. Next, by semidefinite relaxation(SDR) and randomization method, the SDRbased scheme is proposed. In order to reduce the complexity, the closed-form scheme is presented with some simplified measures. Robust beamforming is then studied considering the practical condition. The simulation results such as MSE versus signal-noise-ratio(SNR), MSE versus the iteration number, well prove the performance of the proposed schemes for the system model.
基金supported in part by the National Natural Science Foundation of China(No.61401330,No.61371127)
文摘In this paper, we propose the decode-and-forward(DF) based bidirectional wireless information and power transfer(BWIPT) in two-hop relay systems, where the bidirectional relay can decode and forward information from the user to the access point(AP), and assist the wireless power transfer from the AP to the user. To maximize the information rate from the user to the AP, we derive the closed form expression of the optimal power splitting(PS) factor, and the time allocation scheme to obtain the optimal time switching(TS) factor. Simulation results show that for both PS and TS protocols, the proposed DF based bidirectional relay systems can improve the information rate as compared with the amplify-and-forward(AF) based bidirectional relay systems.
文摘Regarding mobile machinery, particularly agricultural tractors, there is an ongoing competition for the most suitable technology to achieve optimum functionality with maximum efficiency. In this competition, the efficiency of electric series-hybrid powertrains （ESHPs） is often depicted as worse than the efficiency of mechanical-hydraulic power-split powertrains （MHPSPs）. On closer inspection of these statements, however, systematic errors, such as unequal balance limits, neglected size effects and nonlinearities, non-observance of recent technical developments and standards, or erroneous application of research results regarding MHPSPs on ESHPs are often evident. For verification （and under avoidance of the systematic errors mentioned above）, the losses of an ESHP of 150 kW power are for example calculated and compared with the losses of a typical MHPSP of the same power. The comparison of the losses shows that the ESHP clearly exceeds the efficiency of the comparative MHPSP in the main working range and that there is still potential for improvement.
