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
In this study, tractor power output, fuel consumption rate and work performance were indirectly predicted in order to develop an eco driving system. Firstly, equations were developed which could foretell tractor power...In this study, tractor power output, fuel consumption rate and work performance were indirectly predicted in order to develop an eco driving system. Firstly, equations were developed which could foretell tractor power output and fuel consumption rate using characteristic curves of tractor power output. Secondly, with actual engine revolution per minute （rpm） determined by initial engine rpm and work load, tractor power output and fuel consumption rate were forecasted. Thirdly, it was possible to foresee tractor work performance and fuel consumption rate by the speed signals of Global Positioning System （GPS）. Lastly, precision of the eco driving system was evaluated through tractor Power Take-Off （PTO） test, and effects of the eco driving system were investigated in the plowing and rotary tilling operations. Engine rpm, power output, fuel consumption rate, work performance and fuel consumption rate per plot area were displayed on the eco driving system. Predicted tractor power outputs in the full load curve were well coincided with the actual power output of prototype, but small differences, 1 to 6 kW were found in the part load curve. Error of the fuel consumption rate was 0.5 to 3 L/h at the part load curve. It was shown that 69% and 53% of fuel consumption rates could be reduced in plowing and rotary tilling operations, respectively, when the eco driving system was installed in tractor.展开更多
A power saving frequency difference controlling method was introduced by the double inverter and motor experiment system.The characters of the system under differ- ent loads were investigated.The theoretical analysis ...A power saving frequency difference controlling method was introduced by the double inverter and motor experiment system.The characters of the system under differ- ent loads were investigated.The theoretical analysis and experiment results show the frequency difference method is a ideal power saving speed regulation method for the dou- ble inverter and motor system.The experiment system is simply structured,convenient to operate and provides a new way of character testing for frequency conversion speed regulation.展开更多
This work discusses the combination of two thermodynamic cycles seeking to improve the overall chemical energy conversion rate into mechanical energy. Here one engine operates according a Rankine cycle in order to use...This work discusses the combination of two thermodynamic cycles seeking to improve the overall chemical energy conversion rate into mechanical energy. Here one engine operates according a Rankine cycle in order to use part of the thermal energy released to the boundary, i.e., the neighboring atmosphere. The analysis of this combined cycle shows that it might, under proper condition, represent a gain of 1.2% in the overall delivered engine power.展开更多
The heat storage solar Stirling generator referred in this paper is a power conversion unit integrating sunlight receiver, regenerative chamber, Stirling engine and generator, which increases a heat storage function r...The heat storage solar Stirling generator referred in this paper is a power conversion unit integrating sunlight receiver, regenerative chamber, Stirling engine and generator, which increases a heat storage function relative to similar power conversion units. This power conversion unit adopts invention patents authorized in China in recent years to apply to dish solar Stirling thermal power system, and it will be sure to become a principal part of future energy internet and the optimal technical route of CSP （concentrating solar power）. The trough system rests on that Stirling generator substitutes the steam turbine to desalt seawater by remaining heat during power generation. Accordingly, the tower system will be rejected.展开更多
The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks （CRNs）. Existing research has focused on the dual-hop network, which cannot be extend...The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks （CRNs）. Existing research has focused on the dual-hop network, which cannot be extended to a triple-hop network due to its shortcomings, including the limited transmission range and one-way communication. In this paper, a novel, triple-hop relay scheme is proposed to implement time-division duplex （TDD） transmission among secondary users （SUs） in a three-phase transmission. Moreover, a superposition coding （SC） method is adopted for handling two-receiver cases in triple-hop networks with a cognitive relay. We studied a joint optimization of time and power allocation in all three phases, which is formulated as a nonlinear and concave problem. Both analytical and numerical results show that the proposed scheme is able to improve the throughput of SUs, and enlarge the transmission range of primary users （PUs） without increasing the number of hops.展开更多
Clusters of water molecules have low ionization energies because of stabilization of charge from the dipole moment of surrounding molecules,and thus can form potential traps resulting in the undesirable photovoltaic p...Clusters of water molecules have low ionization energies because of stabilization of charge from the dipole moment of surrounding molecules,and thus can form potential traps resulting in the undesirable photovoltaic performance in organic solar cells(OSCs).Herein,we demonstrated a solvent-water evaporation(SWE)strategy,which can effectively remove the water-induced traps that are omnipresent in photoactive layers,leading to a significant improvement in device performance.A higher power conversion efficiency of 17.10%and a better device photostability are achieved by using this SWE method,as compared with the untreated binary PM6:Y6 system(15.83%).We highlight the water-related traps as a limiting factor for carrier transport and extraction properties,and further reveal the good universality of the SWE strategy applied into OSCs.In addition,organic light-emitting diodes and organic field-effect transistors are investigated to demonstrate the applicability of this SWE approach.This strategy presents a major step forward for advancing the field of organic electronics.展开更多
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In this study, tractor power output, fuel consumption rate and work performance were indirectly predicted in order to develop an eco driving system. Firstly, equations were developed which could foretell tractor power output and fuel consumption rate using characteristic curves of tractor power output. Secondly, with actual engine revolution per minute （rpm） determined by initial engine rpm and work load, tractor power output and fuel consumption rate were forecasted. Thirdly, it was possible to foresee tractor work performance and fuel consumption rate by the speed signals of Global Positioning System （GPS）. Lastly, precision of the eco driving system was evaluated through tractor Power Take-Off （PTO） test, and effects of the eco driving system were investigated in the plowing and rotary tilling operations. Engine rpm, power output, fuel consumption rate, work performance and fuel consumption rate per plot area were displayed on the eco driving system. Predicted tractor power outputs in the full load curve were well coincided with the actual power output of prototype, but small differences, 1 to 6 kW were found in the part load curve. Error of the fuel consumption rate was 0.5 to 3 L/h at the part load curve. It was shown that 69% and 53% of fuel consumption rates could be reduced in plowing and rotary tilling operations, respectively, when the eco driving system was installed in tractor.
文摘A power saving frequency difference controlling method was introduced by the double inverter and motor experiment system.The characters of the system under differ- ent loads were investigated.The theoretical analysis and experiment results show the frequency difference method is a ideal power saving speed regulation method for the dou- ble inverter and motor system.The experiment system is simply structured,convenient to operate and provides a new way of character testing for frequency conversion speed regulation.
文摘This work discusses the combination of two thermodynamic cycles seeking to improve the overall chemical energy conversion rate into mechanical energy. Here one engine operates according a Rankine cycle in order to use part of the thermal energy released to the boundary, i.e., the neighboring atmosphere. The analysis of this combined cycle shows that it might, under proper condition, represent a gain of 1.2% in the overall delivered engine power.
文摘The heat storage solar Stirling generator referred in this paper is a power conversion unit integrating sunlight receiver, regenerative chamber, Stirling engine and generator, which increases a heat storage function relative to similar power conversion units. This power conversion unit adopts invention patents authorized in China in recent years to apply to dish solar Stirling thermal power system, and it will be sure to become a principal part of future energy internet and the optimal technical route of CSP （concentrating solar power）. The trough system rests on that Stirling generator substitutes the steam turbine to desalt seawater by remaining heat during power generation. Accordingly, the tower system will be rejected.
基金Project supported by the Zhejiang Provincial National Natural Science Foundation （No. LQ14F020005）, the National Natural Science Foundation of China （Nos. 61379123 and 61402414）, and the Research Program of the Educational Commission of Zhej iang Province, China （No. Y201431815）
文摘The optimization of the network throughput and transmission range is one of the most important issues in cognitive relay networks （CRNs）. Existing research has focused on the dual-hop network, which cannot be extended to a triple-hop network due to its shortcomings, including the limited transmission range and one-way communication. In this paper, a novel, triple-hop relay scheme is proposed to implement time-division duplex （TDD） transmission among secondary users （SUs） in a three-phase transmission. Moreover, a superposition coding （SC） method is adopted for handling two-receiver cases in triple-hop networks with a cognitive relay. We studied a joint optimization of time and power allocation in all three phases, which is formulated as a nonlinear and concave problem. Both analytical and numerical results show that the proposed scheme is able to improve the throughput of SUs, and enlarge the transmission range of primary users （PUs） without increasing the number of hops.
基金the National Natural Science Foundation of China(NSFC)(51773157 and 52061135206)the Fundamental Research Funds for the Central UniversitiesThe authors also thank the support of the opening project of Key Laboratory of Materials Processing and Mold and Beijing National Laboratory for Molecular Sciences(BNLMS201905).
文摘Clusters of water molecules have low ionization energies because of stabilization of charge from the dipole moment of surrounding molecules,and thus can form potential traps resulting in the undesirable photovoltaic performance in organic solar cells(OSCs).Herein,we demonstrated a solvent-water evaporation(SWE)strategy,which can effectively remove the water-induced traps that are omnipresent in photoactive layers,leading to a significant improvement in device performance.A higher power conversion efficiency of 17.10%and a better device photostability are achieved by using this SWE method,as compared with the untreated binary PM6:Y6 system(15.83%).We highlight the water-related traps as a limiting factor for carrier transport and extraction properties,and further reveal the good universality of the SWE strategy applied into OSCs.In addition,organic light-emitting diodes and organic field-effect transistors are investigated to demonstrate the applicability of this SWE approach.This strategy presents a major step forward for advancing the field of organic electronics.
