Based on the measurement of the contrast ratios of the transmission spectra from the throughput and drop ports of ring resonator, an efficient method is proposed to extract the coupling ratio and round-trip loss of th...Based on the measurement of the contrast ratios of the transmission spectra from the throughput and drop ports of ring resonator, an efficient method is proposed to extract the coupling ratio and round-trip loss of the integrated optical waveguide ring resonator. The parameters of a racetrack resonator prepared by ion-exchange technique in K9 optical glass substrate are examined, which demonstrates the validity of this method. The accuracy and applicable range of this method are also discussed.展开更多
With observations and reflections on a series of phenomena,such as the ＂independent situation＂of China＇s FDI during the recent global financial risis and the increase of round tripped investment after the ＂tax rat...With observations and reflections on a series of phenomena,such as the ＂independent situation＂of China＇s FDI during the recent global financial risis and the increase of round tripped investment after the ＂tax rate unification,＂this paper examines a unique phenomenon in China＇s FDI-round tripped investment.It reveals its determinants from a micro-perspectiv ,and establishes a vector error correction mode（VECM）for emprirical testing.The results is that the determinants of China＇s round tripped investment are institutional factors such as ＂achievable differential treatment＂ and cpaital control.Tax ,exchange rate,housing price and capital control intensity all have an impact on the scale of round tripped FDI.However,judging from the extent of influence,the most important factor should be exchange rate ,followed by capital control intensity and housing price,and tax has a limited impact.展开更多
Triboelectric nanogenerator(TENG)has made significant progress in wind energy harvesting.As the most advantageous rotary TENG among wind energy harvesters,the severe material wear and the output that fluctuates with w...Triboelectric nanogenerator(TENG)has made significant progress in wind energy harvesting.As the most advantageous rotary TENG among wind energy harvesters,the severe material wear and the output that fluctuates with wind speed seriously hinder the application of TENG wind energy harvesters.In this study,we propose a round-trip oscillation triboelectric nanogenerator(RTO-TENG)consisting of a crank transmission mechanism and a power generation unit.The RTO-TENG utilizes a simple crank transmission mechanism combined with a zigzag-laminated triboelectric nanogenerator(Z-TENG)to achieve high-performance constant output and low material wear.The crank transmission mechanism can realize the transformation from circular motion to arc reciprocating motion,converting the random wind energy into bi-directional kinetic energy,driving the vertical contact and separation of the Z-TENG.Due to the low transmission ratio(1:1)of the crank transmission mechanism and the consistent frequency of the Z-TENG contact–separation with that of the pendulum,the RTO-TENG’s power generation unit(10 Z-TENGs)is insensitive to changes in wind speed,resulting in a constant and stable output response at various speeds.After 480,000 cycles,the output of RTO-TENG decreased by only 0.9%compared to the initial value of 6μC,and the scanning electron microscopy(SEM)images of the polytetrafluoroethylene(PTFE)film showed no significant wear on the surface of the friction layer,demonstrating excellent output stability and abrasion resistance of the RTO-TENG wind energy collector’s material.The equipped energy management module,based on a gas discharge tube switch,can further enhance the output performance of the RTO-TENG.After optimizing its inductor parameter L to match the load capacitor,it can charge a 220μF load capacitor to 13.4 V in 40 s,resulting in a 298%improvement in charging speed compared to the voltage of 4.48 V without the management module.Therefore,the RTO-TENG can efficiently provide power to low-power small electronic devices for Internet of Things(IoTs),such as road traffic warning signs and thermo-hygrometers.展开更多
Rechargeable neutral aqueous zinc-air batteries(ZABs)are a promising type of energy storage device with longer operating life and less corrosiveness compared with conventional alkaline ZABs.However,the neutral ZABs no...Rechargeable neutral aqueous zinc-air batteries(ZABs)are a promising type of energy storage device with longer operating life and less corrosiveness compared with conventional alkaline ZABs.However,the neutral ZABs normally possess poor oxygen evolution reactions(OERs)and oxygen reduction reactions performance,resulting in a large charge–discharge voltage gap and low round-trip efficiency.Herein,we demonstrate a sunlight-assisted strategy for achieving an ultralow voltage gap of 0.05 V in neutral ZABs by using the FeOOH-decorated BiVO4(Fe-BiVO4)as an oxygen catalyst.Under sunlight,the electrons move from the valence band(VB)of Fe-BiVO_(4) to the conduction band producing holes in VB to promote the OER process and hence reduce the overpotential.Meanwhile,the photopotential generated by the Fe-BiVO_(4) compensates a part of the charging potential of neutral ZABs.Accordingly,the energy loss of the battery could be compensated via solar energy,leading to a record-low gap of 0.05 V between the charge and discharge voltage with a high round-trip efficiency of 94%.This work offers a simple but efficient pathway for solar-energy utilization in storage devices,further guiding the design of high energy efficiency of neutral aqueous ZABs.展开更多
Traditional one-way imaging methods become invalid when a target object is completely hidden behind scattering media. In this case, it has been much more challenging, since the light wave is distorted twice.To solve t...Traditional one-way imaging methods become invalid when a target object is completely hidden behind scattering media. In this case, it has been much more challenging, since the light wave is distorted twice.To solve this problem, we propose an imaging method, so-called round-trip imaging, based on the optical transmission matrix of the scattering medium. We show that the object can be recovered directly from the distorted output wave, where no scanning is required during the imaging process. We predict that this method might improve the imaging speed and have potential application for real-time imaging.展开更多
This study is a detailed analysis of Speculation Game,a simple agent-based model of financial markets,in which the round-trip trading and the dynamic wealth evolution with variable trading volumes are implemented.Inst...This study is a detailed analysis of Speculation Game,a simple agent-based model of financial markets,in which the round-trip trading and the dynamic wealth evolution with variable trading volumes are implemented.Instead of herding behavior,the authors find that the heterogeneous holding periods in round-trip trades can contribute to the emergence of volatility clustering.In particular,the spontaneous redistribution of market wealth through repetitions of round-trip trades with non-uniform horizons can widen the wealth disparity and establish the Pareto distribution of the capital size.As a result,the intermittent placements of relatively big orders from endogenously emerged rich traders can bring on large fluctuations in price return.Empirical data are used to support the scenario derived from the model.展开更多
基金National Natural Science Foundation of China(60577014)Young Teacher Cultivation Foundation of Dalian University of Technology(893210) Doctor Start-up Foundation of Dalian University of Technology(893322)
文摘Based on the measurement of the contrast ratios of the transmission spectra from the throughput and drop ports of ring resonator, an efficient method is proposed to extract the coupling ratio and round-trip loss of the integrated optical waveguide ring resonator. The parameters of a racetrack resonator prepared by ion-exchange technique in K9 optical glass substrate are examined, which demonstrates the validity of this method. The accuracy and applicable range of this method are also discussed.
文摘With observations and reflections on a series of phenomena,such as the ＂independent situation＂of China＇s FDI during the recent global financial risis and the increase of round tripped investment after the ＂tax rate unification,＂this paper examines a unique phenomenon in China＇s FDI-round tripped investment.It reveals its determinants from a micro-perspectiv ,and establishes a vector error correction mode（VECM）for emprirical testing.The results is that the determinants of China＇s round tripped investment are institutional factors such as ＂achievable differential treatment＂ and cpaital control.Tax ,exchange rate,housing price and capital control intensity all have an impact on the scale of round tripped FDI.However,judging from the extent of influence,the most important factor should be exchange rate ,followed by capital control intensity and housing price,and tax has a limited impact.
基金supported by the Natural Science Foundation of Guangxi Province(No.2021GXNSFAA075009)the Specific Research Project of Guangxi for Research Bases and Talents(No.GUIKEAD22035178)the National Key R&D Project from Minister of Science and Technology(No.2021YFA1201603).
文摘Triboelectric nanogenerator(TENG)has made significant progress in wind energy harvesting.As the most advantageous rotary TENG among wind energy harvesters,the severe material wear and the output that fluctuates with wind speed seriously hinder the application of TENG wind energy harvesters.In this study,we propose a round-trip oscillation triboelectric nanogenerator(RTO-TENG)consisting of a crank transmission mechanism and a power generation unit.The RTO-TENG utilizes a simple crank transmission mechanism combined with a zigzag-laminated triboelectric nanogenerator(Z-TENG)to achieve high-performance constant output and low material wear.The crank transmission mechanism can realize the transformation from circular motion to arc reciprocating motion,converting the random wind energy into bi-directional kinetic energy,driving the vertical contact and separation of the Z-TENG.Due to the low transmission ratio(1:1)of the crank transmission mechanism and the consistent frequency of the Z-TENG contact–separation with that of the pendulum,the RTO-TENG’s power generation unit(10 Z-TENGs)is insensitive to changes in wind speed,resulting in a constant and stable output response at various speeds.After 480,000 cycles,the output of RTO-TENG decreased by only 0.9%compared to the initial value of 6μC,and the scanning electron microscopy(SEM)images of the polytetrafluoroethylene(PTFE)film showed no significant wear on the surface of the friction layer,demonstrating excellent output stability and abrasion resistance of the RTO-TENG wind energy collector’s material.The equipped energy management module,based on a gas discharge tube switch,can further enhance the output performance of the RTO-TENG.After optimizing its inductor parameter L to match the load capacitor,it can charge a 220μF load capacitor to 13.4 V in 40 s,resulting in a 298%improvement in charging speed compared to the voltage of 4.48 V without the management module.Therefore,the RTO-TENG can efficiently provide power to low-power small electronic devices for Internet of Things(IoTs),such as road traffic warning signs and thermo-hygrometers.
基金This work was supported by the National Natural Science Foundation of China(Grant No.22278349)Natural Science Foundation of Hebei Province(Grant No.B2023203026)+2 种基金Youth Foundation of Hebei Educational Committee(Grant No.QN2020137)Cultivation Project for Basic Research and Innovation of Yanshan University(Grant No.2021LGZD015)Subsidy for Hebei Key Laboratory of Applied Chemistry after Operation Performance(Grant No.22567616H).
文摘Rechargeable neutral aqueous zinc-air batteries(ZABs)are a promising type of energy storage device with longer operating life and less corrosiveness compared with conventional alkaline ZABs.However,the neutral ZABs normally possess poor oxygen evolution reactions(OERs)and oxygen reduction reactions performance,resulting in a large charge–discharge voltage gap and low round-trip efficiency.Herein,we demonstrate a sunlight-assisted strategy for achieving an ultralow voltage gap of 0.05 V in neutral ZABs by using the FeOOH-decorated BiVO4(Fe-BiVO4)as an oxygen catalyst.Under sunlight,the electrons move from the valence band(VB)of Fe-BiVO_(4) to the conduction band producing holes in VB to promote the OER process and hence reduce the overpotential.Meanwhile,the photopotential generated by the Fe-BiVO_(4) compensates a part of the charging potential of neutral ZABs.Accordingly,the energy loss of the battery could be compensated via solar energy,leading to a record-low gap of 0.05 V between the charge and discharge voltage with a high round-trip efficiency of 94%.This work offers a simple but efficient pathway for solar-energy utilization in storage devices,further guiding the design of high energy efficiency of neutral aqueous ZABs.
基金supported by the National Natural Science Foundation of China(Nos.61535015,61275149,and 61275086)the Special Scientific Research Plan from Education Department of Shaanxi Provincial Government(No.16JK1083)
文摘Traditional one-way imaging methods become invalid when a target object is completely hidden behind scattering media. In this case, it has been much more challenging, since the light wave is distorted twice.To solve this problem, we propose an imaging method, so-called round-trip imaging, based on the optical transmission matrix of the scattering medium. We show that the object can be recovered directly from the distorted output wave, where no scanning is required during the imaging process. We predict that this method might improve the imaging speed and have potential application for real-time imaging.
基金supported by JSPS KAKENHI under Grant Nos.JP17J09156 and JP20J00107。
文摘This study is a detailed analysis of Speculation Game,a simple agent-based model of financial markets,in which the round-trip trading and the dynamic wealth evolution with variable trading volumes are implemented.Instead of herding behavior,the authors find that the heterogeneous holding periods in round-trip trades can contribute to the emergence of volatility clustering.In particular,the spontaneous redistribution of market wealth through repetitions of round-trip trades with non-uniform horizons can widen the wealth disparity and establish the Pareto distribution of the capital size.As a result,the intermittent placements of relatively big orders from endogenously emerged rich traders can bring on large fluctuations in price return.Empirical data are used to support the scenario derived from the model.
