To describe the dynamic response characteristics of the laminated graded-bandgap GaAs-based photocathode with distributed Bragg reflection structure,a general theoretical temporal response model is deduced by combinin...To describe the dynamic response characteristics of the laminated graded-bandgap GaAs-based photocathode with distributed Bragg reflection structure,a general theoretical temporal response model is deduced by combining the unsteady continuity equation and numerical calculation method.Through the model,the contribution of the distribution Bragg reflec-tion structure and graded-bandgap emission layer to the temporal response are investigated.Meanwhile,the relationships between the temporal response characteristics of the laminated GaAs-based photocathode and different structural parame-ters are also analyzed,including average electron decay time,emission layer thickness,and incident light wavelength.It is found that the introduction of distribution Bragg reflection(DBR)layer solves the discrepancy between the absorption capability of the emission layer and the temporal response.Moreover,the distributed Bragg reflection layer can improve the time response by optimizing the initial photoelectron distribution.The improvement effect of the DBR layer on the temporal response is enhanced with the emission layer thickness decreasing or the incident light wavelength increasing.These results explain the effect of the DBR layer of the photocathode on the dynamic characteristics,which can offer a new insight into the dynamic research of GaAs-based photocathode.展开更多
Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased subst...Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased substantially, in particular, average length of fish in 2008 was reduced by ~85% than those occurring in 1985, and at that time ~93% of the total catch was dominated by one-year-old individuals. Correspondingly, growth parameters also varied significantly over the years, i.e., k（growth coefficient） and t_0（zero-length age） gradually increased from 0.26 and –0.58 year in 1960 to 0.56 and –0.25 year in 2008, respectively. Although, L∞（body length）sharply decreased from 34.21 cm in 1960 to 24.06 cm in 2008, and t_r（inflexion age） decreased from 3.78 year in1960 to 1.61 year in 2008. There was a great increase both in natural mortality coefficient and fishing mortality coefficient. However, according to the gray correlation analysis, changes in the biological characteristics of small yellow croaker were induced by different stressors ranked as： fishing vessel power〉feeding grade〉sea surface temperature. This study suggests that the active fishery management measures for biological characters of fish populations should be considered.展开更多
Space-division multiplexing(SDM)offers a promising route to scaling data throughput in fiber-optic networks,but it also introduces challenges such as mode-dependent loss(MDL)and intermodal crosstalk,which increase the...Space-division multiplexing(SDM)offers a promising route to scaling data throughput in fiber-optic networks,but it also introduces challenges such as mode-dependent loss(MDL)and intermodal crosstalk,which increase the computational load on digital signal processing(DSP).Periodic mode mixing has been shown to mitigate these effects by redistributing loss and gain across modes and shortening the effective temporal impulse response over which crosstalk accumulates.In this work,we present a novel and compact mode-scrambling device,3D printed directly onto the facet of a few-mode fiber.展开更多
In studies of auditory perception, a dichotomy between envelope and temporal fine structure(TFS) has been emphasized. It has been shown that frequency-following responses(FFRs) in the rat inferior colliculus can be di...In studies of auditory perception, a dichotomy between envelope and temporal fine structure(TFS) has been emphasized. It has been shown that frequency-following responses(FFRs) in the rat inferior colliculus can be divided into the envelope component(FFREnv)and the temporal fine structure component(FFRTFS). However, the existing FFR models cannot successfully separate FFREnv and FFRTFS. This study was to develop a new FFR model to effectively distinguish FFREnv from FFRTFS by both combining the advantages of the two existing FFR models and simultaneously adding cellular properties of inferior colliculus neurons. To evaluate the validity of the present model, correlations between simulated FFRs and experimental data from the rat inferior colliculus were calculated. Different model parameters were tested, FFRs were calculated, and the parameters with highest prediction were chosen to establish an ideal FFR model. The results indicate that the new FFR model can provide reliable predictions for experimentally obtained FFREnv and FFRTFS.展开更多
Mechanoluminescence(ML)is bringing a paradigm-shifting for next-generation lightbased human–robot interaction.However,the overlooked character of ML temporal dynamic response remains a critical barrier to overcoming ...Mechanoluminescence(ML)is bringing a paradigm-shifting for next-generation lightbased human–robot interaction.However,the overlooked character of ML temporal dynamic response remains a critical barrier to overcoming the limitation of mechanooptical conversion efficiency.Here,by resolving the dynamic interplay among stimuli rate,interfacial charge accumulation and ML performance of three typical materials,like ZnS:Cu^(2+),SrAl_(2)O_(4):Eu^(2+),Dy^(3+),Y_(3)Al_(5)O_(12):Ce^(3+),the cognition of ML has been deeply understand.Obviously,the ML performance is predominantly governed by the crosscoupling of stimuli rate and stimuli time rather than absolute stress magnitude.For the first time,the optimal stretching stimulation rate for commercial ZnS:Cu^(2+),SrAl_(2)O_(4):Eu^(2+),Dy^(3+)and Y_(3)Al_(5)O_(12):Ce^(3+)are respectively determined as~10.3 Mpa/s,~11.0 Mpa/s,~31.9 Mpa/s,which is of great significance for obtaining high-performance ML behavior,and an ubiquitous ML hysteresis phenomenon is demonstrated originating from a time-consuming mechano-electro-optical conversion process even existing in trap-controlled SrAl_(2)O_(4):Eu^(2+),Dy^(3+).Moreover,a qualitative relationship for ML brightness(MLB),stimuli rate(sr),stimuli time(st),inherent interfacial triboelectricity coefficient(iitre)and relative interfacial triboelectricity coefficient(ritre)is established as ML B=f(sr)*g(st)*p(iitre)*q(ritre)for guiding the design of ML elastomers.For instance,based on this equation,a topology-optimized Y_(3)Al_(5)O_(12):Ce^(3+)@polydimethylsiloxane(PDMS)elastomer is engineered,achieving unprecedented 693 times brighter emission,78%lower stress threshold and 20%lighter weight,which is successfully applied in remote control(~450 m)of quadruped robot.Three main contributions of this work include:(i)demonstrating the influence law of temporal dynamic stimulation on ML performance.(ii)resolving long-standing mechano-optical asynchrony debates.(iii)establishing a universal guideline for designing high-performance ML platforms.展开更多
Understanding how drivers perceive and respond to external stimuli in driving tasks is important for the development of advanced driving technologies and human-computer interaction.In this paper,we conducted a tempora...Understanding how drivers perceive and respond to external stimuli in driving tasks is important for the development of advanced driving technologies and human-computer interaction.In this paper,we conducted a temporal response analysis between driving data and cortical activation data measured by functional near-infrared spectroscopy(fNIRS),based on a naturalistic driving experiment.Temporal response function analysis indicates that stimuli,which elicit significant responses of drivers include distance,acceleration,time headway,and the velocity of the preceding vehicle.For these stimuli,the time lags and response patterns were further discussed.The influencing factors on drivers’perception were also studied based on various driver characteristics.These conclusions can provide guidance for the construction of car-following models,the safety assessment of drivers and the improvement of advanced driving technologies.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U2141239 and 61771245)the Fund from the Science and Technology on Low-Light-Level Night Vision Laboratory of China(Grant No.J20200102).
文摘To describe the dynamic response characteristics of the laminated graded-bandgap GaAs-based photocathode with distributed Bragg reflection structure,a general theoretical temporal response model is deduced by combining the unsteady continuity equation and numerical calculation method.Through the model,the contribution of the distribution Bragg reflec-tion structure and graded-bandgap emission layer to the temporal response are investigated.Meanwhile,the relationships between the temporal response characteristics of the laminated GaAs-based photocathode and different structural parame-ters are also analyzed,including average electron decay time,emission layer thickness,and incident light wavelength.It is found that the introduction of distribution Bragg reflection(DBR)layer solves the discrepancy between the absorption capability of the emission layer and the temporal response.Moreover,the distributed Bragg reflection layer can improve the time response by optimizing the initial photoelectron distribution.The improvement effect of the DBR layer on the temporal response is enhanced with the emission layer thickness decreasing or the incident light wavelength increasing.These results explain the effect of the DBR layer of the photocathode on the dynamic characteristics,which can offer a new insight into the dynamic research of GaAs-based photocathode.
基金The National Basic Research Program(973 Program)of China under contract No.2015CB453303the Aoshan Scientific and Technical Innovation Program under contract No.2015ASKJ02-05the Taishan Scholar Project Special Fund
文摘Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased substantially, in particular, average length of fish in 2008 was reduced by ~85% than those occurring in 1985, and at that time ~93% of the total catch was dominated by one-year-old individuals. Correspondingly, growth parameters also varied significantly over the years, i.e., k（growth coefficient） and t_0（zero-length age） gradually increased from 0.26 and –0.58 year in 1960 to 0.56 and –0.25 year in 2008, respectively. Although, L∞（body length）sharply decreased from 34.21 cm in 1960 to 24.06 cm in 2008, and t_r（inflexion age） decreased from 3.78 year in1960 to 1.61 year in 2008. There was a great increase both in natural mortality coefficient and fishing mortality coefficient. However, according to the gray correlation analysis, changes in the biological characteristics of small yellow croaker were induced by different stressors ranked as： fishing vessel power〉feeding grade〉sea surface temperature. This study suggests that the active fishery management measures for biological characters of fish populations should be considered.
基金Horizon 2020 Framework Programme(619732)Ministry of Innovation,Science and Technology,Fulbright U.S.Scholar Program。
文摘Space-division multiplexing(SDM)offers a promising route to scaling data throughput in fiber-optic networks,but it also introduces challenges such as mode-dependent loss(MDL)and intermodal crosstalk,which increase the computational load on digital signal processing(DSP).Periodic mode mixing has been shown to mitigate these effects by redistributing loss and gain across modes and shortening the effective temporal impulse response over which crosstalk accumulates.In this work,we present a novel and compact mode-scrambling device,3D printed directly onto the facet of a few-mode fiber.
基金supported by the National Natural Science Foundation of China(Grant No.31470987)the National Basic Research Development Program of China(Grant No.2015CB351800)“985”grants from Peking University for Physiological Psychology and China Postdoctoral Science Foundation(Grant No.2016M601066)
文摘In studies of auditory perception, a dichotomy between envelope and temporal fine structure(TFS) has been emphasized. It has been shown that frequency-following responses(FFRs) in the rat inferior colliculus can be divided into the envelope component(FFREnv)and the temporal fine structure component(FFRTFS). However, the existing FFR models cannot successfully separate FFREnv and FFRTFS. This study was to develop a new FFR model to effectively distinguish FFREnv from FFRTFS by both combining the advantages of the two existing FFR models and simultaneously adding cellular properties of inferior colliculus neurons. To evaluate the validity of the present model, correlations between simulated FFRs and experimental data from the rat inferior colliculus were calculated. Different model parameters were tested, FFRs were calculated, and the parameters with highest prediction were chosen to establish an ideal FFR model. The results indicate that the new FFR model can provide reliable predictions for experimentally obtained FFREnv and FFRTFS.
基金financially supported by National Natural Science Foundation of China(U24A20307,12304460).
文摘Mechanoluminescence(ML)is bringing a paradigm-shifting for next-generation lightbased human–robot interaction.However,the overlooked character of ML temporal dynamic response remains a critical barrier to overcoming the limitation of mechanooptical conversion efficiency.Here,by resolving the dynamic interplay among stimuli rate,interfacial charge accumulation and ML performance of three typical materials,like ZnS:Cu^(2+),SrAl_(2)O_(4):Eu^(2+),Dy^(3+),Y_(3)Al_(5)O_(12):Ce^(3+),the cognition of ML has been deeply understand.Obviously,the ML performance is predominantly governed by the crosscoupling of stimuli rate and stimuli time rather than absolute stress magnitude.For the first time,the optimal stretching stimulation rate for commercial ZnS:Cu^(2+),SrAl_(2)O_(4):Eu^(2+),Dy^(3+)and Y_(3)Al_(5)O_(12):Ce^(3+)are respectively determined as~10.3 Mpa/s,~11.0 Mpa/s,~31.9 Mpa/s,which is of great significance for obtaining high-performance ML behavior,and an ubiquitous ML hysteresis phenomenon is demonstrated originating from a time-consuming mechano-electro-optical conversion process even existing in trap-controlled SrAl_(2)O_(4):Eu^(2+),Dy^(3+).Moreover,a qualitative relationship for ML brightness(MLB),stimuli rate(sr),stimuli time(st),inherent interfacial triboelectricity coefficient(iitre)and relative interfacial triboelectricity coefficient(ritre)is established as ML B=f(sr)*g(st)*p(iitre)*q(ritre)for guiding the design of ML elastomers.For instance,based on this equation,a topology-optimized Y_(3)Al_(5)O_(12):Ce^(3+)@polydimethylsiloxane(PDMS)elastomer is engineered,achieving unprecedented 693 times brighter emission,78%lower stress threshold and 20%lighter weight,which is successfully applied in remote control(~450 m)of quadruped robot.Three main contributions of this work include:(i)demonstrating the influence law of temporal dynamic stimulation on ML performance.(ii)resolving long-standing mechano-optical asynchrony debates.(iii)establishing a universal guideline for designing high-performance ML platforms.
基金supported by the National Key R&D Program of China(No.2021YFC3001500).
文摘Understanding how drivers perceive and respond to external stimuli in driving tasks is important for the development of advanced driving technologies and human-computer interaction.In this paper,we conducted a temporal response analysis between driving data and cortical activation data measured by functional near-infrared spectroscopy(fNIRS),based on a naturalistic driving experiment.Temporal response function analysis indicates that stimuli,which elicit significant responses of drivers include distance,acceleration,time headway,and the velocity of the preceding vehicle.For these stimuli,the time lags and response patterns were further discussed.The influencing factors on drivers’perception were also studied based on various driver characteristics.These conclusions can provide guidance for the construction of car-following models,the safety assessment of drivers and the improvement of advanced driving technologies.
