An extreme torrential rain(ETR)event occurred in Henan Province,China,during 18-21 July 2021.Based on hourly rain-gauge observations and ERA5 reanalysis data,the ETR was studied from the perspective of kinetic energy(...An extreme torrential rain(ETR)event occurred in Henan Province,China,during 18-21 July 2021.Based on hourly rain-gauge observations and ERA5 reanalysis data,the ETR was studied from the perspective of kinetic energy(K),which can be divided into rotational wind(V_(R))kinetic energy(K_(R)),divergent wind kinetic energy(K_(D)),and the kinetic energy of the interaction between the divergent and rotational winds(K_(RD)).According to the hourly precipitation intensity variability,the ETR process was divided into an initial stage,a rapid increase stage,and maintenance stage.Results showed that the intensification and maintenance of ETR were closely related to the upper-level K,and most closely related to the upperlevel K_(R),with a correlation coefficient of up to 0.9.In particular,the peak value of hourly rainfall intensity lagged behind the K_(R) by 8 h.Furthermore,diagnosis showed that K transformation from unresolvable to resolvable scales made the ETR increase slowly.The meridional rotational wind(u_(R))and meridional gradient of the geopotential(φ)jointly determined the conversion of available potential energy(APE)to K_(R) through the barotropic process,which dominated the rapid enhancement of K_(R) and then caused the rapid increase in ETR.The transportation of K by rotational wind consumed K_(R),and basically offset the K_(R) produced by the barotropic process,which basically kept K_(R) stable at a high value,thus maintaining the ETR.展开更多
In this study,we put forward a radiative-convective-transportive energy balance model of a gray atmosphere to examine individual roles of the greenhouse effect of water vapor,vertical convection,and atmospheric polewa...In this study,we put forward a radiative-convective-transportive energy balance model of a gray atmosphere to examine individual roles of the greenhouse effect of water vapor,vertical convection,and atmospheric poleward energy transport as well as their combined effects for a quasi-linear relationship between the outgoing longwave radiation(OLR)and surface temperature(T_(S)).The greenhouse effect of water vapor enhances the meridional gradient of surface temperature,thereby directly contributing to a quasi-linear OLR-T_(S) relationship.The atmospheric poleward energy transport decreases the meridional gradient of surface temperature.As a result of the poleward energy transport,tropical(high-latitude)atmosphere-surface columns emit less(more)OLR than the solar energy input at their respective locations,causing a substantial reduction of the meridional gradient of the OLR.The combined effect of reducing the meridional gradients of both OLR and surface temperature by the poleward energy transport also contributes to the quasi-linear OLR-T_(S) relationship.Vertical convective energy transport reduces the meridional gradient of surface temperature without affecting the meridional gradient of OLR,thereby suppressing part of the reduction to the increasing rate of OLR with surface temperature by the greenhouse effect of water vapor and poleward energy transport.Because of the nature of the energy balance in the climate system,such a quasi-linear relationship is also a good approximation for the relationship between the annual-mean net downward solar energy flux at the top of the atmosphere and surface temperature.展开更多
In this article, the global existence and the large time behavior of smooth solutions to the initial boundary value problem for a degenerate compressible energy transport model are established.
Under external heating forcing in the Southern Ocean,climate models project anomalous northward atmosphere heat transport(AHT)across the equator,accompanied by a southward shift of the intertropical convergence zone(I...Under external heating forcing in the Southern Ocean,climate models project anomalous northward atmosphere heat transport(AHT)across the equator,accompanied by a southward shift of the intertropical convergence zone(ITCZ).Comparison between a fully coupled and a slab ocean model shows that the inclusion of active ocean dynamics tends to partition the cross-equatorial energy transport and significantly reduce the ITCZ shift response by a factor of 10,a finding which supports previous studies.To understand how ocean dynamics damps the ITCZ’s response to an imposed thermal heating in the Southern Ocean,we examine the ocean heat transport(OHT)and ocean circulation responses in a set of fully coupled experiments.Results show that both the Indo-Pacific and the Atlantic contribute to transport energy across the equator mainly through its Eulerian-mean component.However,different from previous studies that linked the changes in OHT to the changes in the wind-driven subtropical cells or the Atlantic meridional overturning circulation(AMOC),our results show that the cross-equatorial OHT anomaly is due to a broad clockwise overturning circulation anomaly below the subtropical cells(approximately bounded by the 5°C to 20°C isotherms and 50°S to 10°N).Further elimination of the wind-driven component,conducted by prescribing the climatological wind stress in the Southern Ocean heat perturbation experiments,leads to little change in OHT,suggesting that the OHT response is predominantly thermohaline-driven by air-sea thermal interactions.展开更多
Polymers of 1- and 2-vinylnaphthalene containing more than about 50 mol% sulfonic acid groups dissolve in water to form 'hypercoiled' conformations which have many of the properties of micelles. Hydrophobic m...Polymers of 1- and 2-vinylnaphthalene containing more than about 50 mol% sulfonic acid groups dissolve in water to form 'hypercoiled' conformations which have many of the properties of micelles. Hydrophobic molecules such as anthracene and perylene are selectively absorbed in these pseudo micellar structures, and their fluorescence emission is sensitized by energy transfer from the surrounding naphthalene chromophores. When irradiated with UV light in the presence of oxygen, the emission of perylene rapidly decreases. It is proposed that this is due to reaction of singlet oxygen with the perylene trapped in the hypercoiled polymer. (Author abstract) 3 Refs.展开更多
Radial profiles of the ion temperature,Ti,have been measured by a double-sided retarding field analyzer(RFA) in the scrape-off layer(SOL) of the J-TEXT tokamak(R = 105 cm,r = 25-29 cm,Bt = 1.8-2.0 T,Ip = 120-180 ...Radial profiles of the ion temperature,Ti,have been measured by a double-sided retarding field analyzer(RFA) in the scrape-off layer(SOL) of the J-TEXT tokamak(R = 105 cm,r = 25-29 cm,Bt = 1.8-2.0 T,Ip = 120-180 kA,ne =(2-2.5) × 10^19 m^-3).Strongly declining Ti profiles in the SOL have been found.The different e-folding lengths,At,of the Ti profiles in two experimental configurations with different magnetic connection lengths,Lc,reveal that a longer Lc results in weaker parallel energy transport and longer At.In similarity with the particle transport across the SOL,At is approximately proportional to the square root of Lc.Additionally,the poloidal asymmetry has been identified with enhanced ion energy transport across the SOL on the low-field side.展开更多
We show that a current-carrying coherent electron conductor can be treated as an effective bosonic energy reservoir involving different types of electron–hole pair excitations.For weak electron–boson coupling,hybrid...We show that a current-carrying coherent electron conductor can be treated as an effective bosonic energy reservoir involving different types of electron–hole pair excitations.For weak electron–boson coupling,hybrid energy transport between nonequilibrium electrons and bosons can be described by a Landauer-like formula.This allows for unified account of a variety of heat transport problems in hybrid electron–boson systems.As applications,we study the non-reciprocal heat transport between electrons and bosons,thermoelectric current from a cold-spot,and electronic cooling of the bosons.Our unified framework provides an intuitive way of understanding hybrid energy transport between electrons and bosons in their weak coupling limit.It opens the way of nonequilibrium reservoir engineering for efficient energy control between different quasi-particles at the nanoscale.展开更多
We study the dynamical energy equipartition properties in the integrable Toda model with additional uniform or disordered on-site energies by extensive numerical simulations. The total energy is initially equidistribu...We study the dynamical energy equipartition properties in the integrable Toda model with additional uniform or disordered on-site energies by extensive numerical simulations. The total energy is initially equidistributed among some of the lowest frequency linear modes. For the Toda model with uniform on-site potentials, the energy spectrum keeps its profile nearly unchanged in a relatively short time scale. On a much longer time scale, the energies of tail modes increase slowly with time. Energy equipartition is far away from being attached in our studied time scale. For the Toda model with disordered on-site potentials, the energy transfers continuously to the high frequency modes and eventually towards energy equipartition. We further perform a systematic study of the equipartition time teq depending on the energy density ε and the nonlinear parameter α in the thermodynamic limit for the Toda model with disordered on-site potentials. We find teq∝ (1/ε)^a(1/α)^b, where b≈ 2a. The values of a and b are increased when increasing the strengths of disordered on-site potentials or decreasing the number of initially excited modes.展开更多
Land transport can no longer meet the requirements.European transport can be described by these words−crowded motorways and cities,dangerous emissions,ubiquitous traffic accidents,delays,expensive railways.Solutions a...Land transport can no longer meet the requirements.European transport can be described by these words−crowded motorways and cities,dangerous emissions,ubiquitous traffic accidents,delays,expensive railways.Solutions are being sought to transfer a large part of passengers and especially freight transport to(high-speed)rail,and efforts are moving towards electromobility,car-sharing,5G-connectivity,autonomous driving,MaaS(Mobility as a Service)-coordinated transport or hyperloop-type solutions.However,all these solutions have additional challenges and limitations.Solutions are not being searched where they really exist-in the mutual adaptation of road and rail vehicles and their deep cooperation.The ComplexTrans project shows that simply adapting the dimensions and functions of road and rail vehicles can eliminate(or at least significantly reduce)all the problems of existing land transport.The main features of the ComplexTrans system are sufficient parking spaces,reduction of urban and non-urban congestion,electric vehicles with unlimited range and cheaper than standard cars,cheaper and more accessible battery charging,“autonomous ride”,solving the overlap between passenger and freight rail transport and making it self-financing,transferring intercity freight transport to rail,replacing part of continental air transport and many others.The cost-effective and clustered individual transport and individualised public transport of the ComplexTrans system also bring very significant reductions in the risk of transmission of covid-19 and other contagious diseases during transport.展开更多
Phonon polaritons(PhPs)exhibit directional in-plane propagation and ultralow losses in van der Waals(vdW)crystals,offering new possibilities for controlling the flow of light at the nanoscale.However,these PhPs,includ...Phonon polaritons(PhPs)exhibit directional in-plane propagation and ultralow losses in van der Waals(vdW)crystals,offering new possibilities for controlling the flow of light at the nanoscale.However,these PhPs,including their directional propagation,are inherently determined by the anisotropic crystal structure of the host materials.Although in-plane anisotropic PhPs can be manipulated by twisting engineering,such as twisting individual vdW slabs,dynamically adjusting their propagation presents a significant challenge.The limited application of the twisted bilayer structure in bare films further restricts its usage.In this study,we present a technique in which anisotropic PhPs supported by bare biaxial vdW slabs can be actively tuned by modifying their local dielectric environment.Excitingly,we predict that the iso-frequency contour of PhPs can be reoriented to enable propagation along forbidden directions when the crystal is placed on a substrate with a moderate negative permittivity.Besides,we systematically investigate the impact of polaritonic coupling on near-field radiative heat transfer(NFRHT)between heterostructures integrated with different substrates that have negative permittivity.Our main findings reveal that through the analysis of dispersion contour and photon transmission coefficient,the excitation and reorientation of the fundamental mode facilitate increased photon tunneling,thereby enhancing heat transfer between heterostructures.Conversely,the annihilation of the fundamental mode hinders heat transfer.Furthermore,we find the enhancement or suppression of radiative energy transport depends on the relative magnitude of the slab thickness and the vacuum gap width.Finally,the effect of negative permittivity substrates on NFRHT along the[001]crystalline direction ofα-MoO3 is considered.The spectral band where the excited fundamental mode resulting from the negative permittivity substrates is shifted to the first Reststrahlen Band(RB 1)ofα-MoO_(3) and is widened,resulting in more significant enhancement of heat flux from RB 1.We anticipate our results will motivate new direction for dynamical tunability of the PhPs in photonic devices.展开更多
Liquid marbles (non-stick droplets) containing crude petroleum are reported. Liquid marbles were ob- tained by use of fluorinated decyl polyhedral oligomeric silsequioxane (FD-POSS) powder. Marbles containing crud...Liquid marbles (non-stick droplets) containing crude petroleum are reported. Liquid marbles were ob- tained by use of fluorinated decyl polyhedral oligomeric silsequioxane (FD-POSS) powder. Marbles containing crude petroleum remained stable on a broad diversity of solid and liquid supports. The effective surface tension of marbles filled with petroleum was established. The mechanism of friction of the marbles is discussed. Actuation of liquid marbles containing crude petroleum with an electric field is presented.展开更多
Based on the formulation of a multiple non-isotropic scattering process, a characteristic source time is introduced to define the initial impulse width of energy density at the source. An analytical expression of the ...Based on the formulation of a multiple non-isotropic scattering process, a characteristic source time is introduced to define the initial impulse width of energy density at the source. An analytical expression of the initial intensity spectral density of a seismic wave is incorporated into the integral equation of seismic wave energy density. And, a recursive formula of Green's function is derived to obtain the higher order Green's function, which is included to describe the stronger non-isotropic scattering process. Then, the effect of the scattering pattern on the energy density envelope is investigated by the modified scattering theory. Significant differences arc found in the decay of the energy density envelopes with distances using different scattering patterns. The envelope synthesized by the forward dominated scattering pattern is larger than the results obtained by the isotropic and backward dominated scattering pattern. Different scattering patterns are also used to fit the observation data from the aftershocks of the 2008 Wenchuan earthquake. It is concluded that the envelopes synthesized by the forward scattering pattern can match the data better than the isotropic and backward dominated scattering cases, and a new interpretation of the coda wave is given. Finally, using the forward dominated scattering pattern, the envelope broadening of the observed data is reproduced.展开更多
The thermal stability of the soliton excited in the protein molecular system which work at finite temperature and a nonlinear vibration of the molecular chain have beed studied in our theory. The results obtained show...The thermal stability of the soliton excited in the protein molecular system which work at finite temperature and a nonlinear vibration of the molecular chain have beed studied in our theory. The results obtained show that the soliton moves in supersonic velocity and the amplitude of soliton depends on the temperature and the strengthen of nonlinear vibration. but the soliton excited is thermal stable in the case of the physiologic temperature 310K.展开更多
The current interruption capability of a gas, when used in high voltage gas-blast circuit breakers,depends not only on its material properties but also the flow field since turbulence plays a dominant role in arc cool...The current interruption capability of a gas, when used in high voltage gas-blast circuit breakers,depends not only on its material properties but also the flow field since turbulence plays a dominant role in arc cooling during the interruption process. Based on available experimental results, a study of CO2 switching arcs under a DC(direct current) current in the model circuit breaker has been conducted to calibrate CO2 arc model and to analyse its electric and thermal property. Through detailed analysis of the results mechanisms responsible for the temperature distribution are identified and the domain energy transportation process of different region discussed. The present work provides significant coefficients for CO2 switching arc simulation and gives a better understanding of CO2 arc burning mechanisms.展开更多
This work aims to investigate the factors accelerating electric vehicle(EV)acceptance at the consumer end in Pakistan and analyzes the implications for policymakers for a fast-track EV transition.The study further in-...This work aims to investigate the factors accelerating electric vehicle(EV)acceptance at the consumer end in Pakistan and analyzes the implications for policymakers for a fast-track EV transition.The study further in-vestigates the high EV penetration scenario resulting from the technology acceptance model(TAM's 80%EV)and its impact on energy demand and CO_(2)emissions.The study design used a quantitative analysis method with the survey as an instrument for data collection regarding EV acceptance.The model under investigation was adapted from the famous Technology-Acceptance Models(TAMs)and modified with other significant predictors evidenced in the literature.Correlation and stepwise regression were performed with a multicollinearity check for model hypothesis testing.Out of six predictors,only four factors were significant in accelerating the EV transition.Financial policies were found to be highly significant,followed by environmental concern,facilitating conditions and perceived ease of use.The research then used exponential smoothing forecasts for transport demand and developed an EV penetration scenario based on modified TAM results.The results highlight the significant in-crease in transport demand and the opportunity for Pakistan to limit passenger transport emissions to 36.6 MT instead of 61.6 MT by 2040.展开更多
Cassava is a staple food, feed and bioenergy crop important to the world especially in the tropics.Domesticated cassava is characterized by powerful carbohydrate accumulation but its wild progenitor is not.Here, we in...Cassava is a staple food, feed and bioenergy crop important to the world especially in the tropics.Domesticated cassava is characterized by powerful carbohydrate accumulation but its wild progenitor is not.Here, we investigated the transcriptional differences of eight c DNA libraries derived from developing leaf, stem and storage root of cassava cv. Arg7 and an ancestor line,W14, using next generation sequencing system. A total of41302 assembled transcripts were obtained and from these,25961 transcripts with FPKM≥3 in at least one library were named the expressed genes. A total of 2117, 1963 and3584 transcripts were found to be differentially expressed in leaf, stem and storage root(150 d after planting),respectively, between Arg7 and W14 and ascribed to 103,93 and 119 important pathways in leaf, stem and storage root, respectively. The highlight of this work is that the genes involved in light response, such as those for photosystem I(PSA) and photosystem II(PSB), other genes involved in light harvesting, and some of the genes in the Calvin cycle of carbon fixation were specially upregulated in leaf. Genes for transport and also for key rate-limiting enzymes(PFK, PGK and PK, GAPDH)coupling ATP consumption in glycolysis pathway were predominantly expressed in stem, and genes for sucrose degradation(INVs), amylose synthesis(GBSS) and hydrolysis(RCP1, AMYs), the three key steps of starch metabolism, and transport associated with energy translocation(ABC, AVPs and ATPase) and their upstream transcription factors had enhanced expression in storage root in domesticated cassava. Co-expression networks among the pathways in each organs revealed therelationship of the genes involved, and uncovered some of the important hub genes and transcription factors targeting genes for photosynthesis, transportation and starch biosynthesis.展开更多
The role of interface couplings on the energy transport of two coupled Frenkel-Kontorova (FK) chains is explored through numerical simulations. In general, it is expected that the interface cou- plings result in the...The role of interface couplings on the energy transport of two coupled Frenkel-Kontorova (FK) chains is explored through numerical simulations. In general, it is expected that the interface cou- plings result in the suppression of heat conduction through the coupled system due to the additional interface phonon-phonon scattering. In the present paper, it is found that the thermal conductivity increases with increasing intensity of interface interactions for weak inter-chain couplings, whereas the heat conduction is suppressed by the interface interaction in the case of strong inter-chain couplings. Based on the phonon spectral energy density method, we demonstrate that the enhance- ment of energy transport results from the excited phonon modes (in addition to the intrinsic phonon modes), while the strong interface phonon-phonon scattering results in the suppressed energy transport.展开更多
We use 9 years data of Cluster to study the dependencies of plasma parameters and energy transport in the plasma sheet on the lasting time of northward/southward interplanetary magnetic field(IMF). The plasma paramete...We use 9 years data of Cluster to study the dependencies of plasma parameters and energy transport in the plasma sheet on the lasting time of northward/southward interplanetary magnetic field(IMF). The plasma parameters and energy transport in the plasma sheet always respond to the change of IMF direction by more or less time. The ion density starts to increase/decrease remarkably at 80 min after northward/southward IMF turning. The ion temperature starts to decrease at 25 min after northward IMF turning, whereas it starts to increase at 80 min after southward IMF turning. The earthward convection velocity within15 min after northward IMF turning almost equals to that within 15 min period after southward IMF turning. However at time greater than 15 min after southward IMF turning, the earthward convection velocity under southward IMF starts to remarkably increase. The response time(15 min) of magnetospheric convection velocity is well consistent with the response times of nightside ionospheric convection to southward IMF turning. The enthalpy flux is larger than kinetic flux by about three orders of magnitudes, and thus the enthalpy flux plays a dominant role in the plasma sheet energy transport. The enthalpy flux does not weaken immediately after northward IMF turning. The enthalpy flux within 15 min after northward IMF turning is comparable to or even slightly larger than that within 15 min after southward IMF. The enthalpy flux starts to decrease at times greater than15 min after northward IMF turning, whereas it starts to increase at times greater than 15 min after southward IMF turning. The result that the enhanced energy transport during the 15 min period after northward IMF turning may explain previous observation that substorms frequently occur shortly after northward IMF turning.展开更多
Lead iodide single crystal was grown by physical vapor transport method.Two radiation detectors with different configurations were fabricated from the as-grown crystal.The electrical and y-ray response properties at r...Lead iodide single crystal was grown by physical vapor transport method.Two radiation detectors with different configurations were fabricated from the as-grown crystal.The electrical and y-ray response properties at room temperature of the both detectors were investigated.It is found that the dark resistivity of the detectors are respectively 3×10^(10)Ω·cm for bias electric field parallel to crystal c-axis(E//c) and 2×10~8Ω·cm for perpendicular to crystal c-axis(E⊥c).The energy spectrum response measurement shows that both detectors were sensitive to ^(241) Am 59.5 keVγ-rays,and achieved a good energy resolution of 16.8%for the E⊥c-axis configuration detector with a full width at half maximum of 9.996 keV.展开更多
As a key technology for space-based Earth observation and astronomical exploration,cooled mid-wavelength and long-wavelength Infrared(IR)detection is widely used in national defense,astronomy exploration,medical imagi...As a key technology for space-based Earth observation and astronomical exploration,cooled mid-wavelength and long-wavelength Infrared(IR)detection is widely used in national defense,astronomy exploration,medical imaging,environmental monitoring,agricultural and other areas.The performances of IR detectors,including cut-off wavelength,detectivity,sensitivity and temperature resolution,plays a significant role in efficiently observing and tracking the low-temperature far-distance moving targets.Achieving optimal detection performance requires the IR detectors to operate at cryogenic temperatures.The future development of space-based applications relies heavily on the mid-wavelength and long-wavelength IR detection technologies,which should be enabled by the long-life cryogenic refrigeration and high-efficiency energy transportation system operating below 40 K,to support the Earth observation and astronomical detection.However,the efficiency degradation caused by the super low temperature brings tremendous challenges to the life time of cryogenic refrigeration and energy transportation systems.This paper evaluates the influence of cryogenic temperature on the infrared detector performances,reviews the features,development and space applications of cryogenic cooling technologies,as well as the cryogenic energy transportation approaches.Additionally,it analyzes the future development trends and challenges in supporting the space-based IR detection.展开更多
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.42275013,42030611 and 42175008)the Open Grants of the State Key Laboratory of Severe Weather(Grant No.2021LASWB17)。
文摘An extreme torrential rain(ETR)event occurred in Henan Province,China,during 18-21 July 2021.Based on hourly rain-gauge observations and ERA5 reanalysis data,the ETR was studied from the perspective of kinetic energy(K),which can be divided into rotational wind(V_(R))kinetic energy(K_(R)),divergent wind kinetic energy(K_(D)),and the kinetic energy of the interaction between the divergent and rotational winds(K_(RD)).According to the hourly precipitation intensity variability,the ETR process was divided into an initial stage,a rapid increase stage,and maintenance stage.Results showed that the intensification and maintenance of ETR were closely related to the upper-level K,and most closely related to the upperlevel K_(R),with a correlation coefficient of up to 0.9.In particular,the peak value of hourly rainfall intensity lagged behind the K_(R) by 8 h.Furthermore,diagnosis showed that K transformation from unresolvable to resolvable scales made the ETR increase slowly.The meridional rotational wind(u_(R))and meridional gradient of the geopotential(φ)jointly determined the conversion of available potential energy(APE)to K_(R) through the barotropic process,which dominated the rapid enhancement of K_(R) and then caused the rapid increase in ETR.The transportation of K by rotational wind consumed K_(R),and basically offset the K_(R) produced by the barotropic process,which basically kept K_(R) stable at a high value,thus maintaining the ETR.
基金part supported by grants from the National Natural Science Foundation of China(Grant Nos.42222502 and 42075028)grants from the National Science Foundation(AGS-2032542 and AGS-2202875)。
文摘In this study,we put forward a radiative-convective-transportive energy balance model of a gray atmosphere to examine individual roles of the greenhouse effect of water vapor,vertical convection,and atmospheric poleward energy transport as well as their combined effects for a quasi-linear relationship between the outgoing longwave radiation(OLR)and surface temperature(T_(S)).The greenhouse effect of water vapor enhances the meridional gradient of surface temperature,thereby directly contributing to a quasi-linear OLR-T_(S) relationship.The atmospheric poleward energy transport decreases the meridional gradient of surface temperature.As a result of the poleward energy transport,tropical(high-latitude)atmosphere-surface columns emit less(more)OLR than the solar energy input at their respective locations,causing a substantial reduction of the meridional gradient of the OLR.The combined effect of reducing the meridional gradients of both OLR and surface temperature by the poleward energy transport also contributes to the quasi-linear OLR-T_(S) relationship.Vertical convective energy transport reduces the meridional gradient of surface temperature without affecting the meridional gradient of OLR,thereby suppressing part of the reduction to the increasing rate of OLR with surface temperature by the greenhouse effect of water vapor and poleward energy transport.Because of the nature of the energy balance in the climate system,such a quasi-linear relationship is also a good approximation for the relationship between the annual-mean net downward solar energy flux at the top of the atmosphere and surface temperature.
基金Supported by the Foundation for Talents of Beijing (20081D0501500171)the Funds of Beijing University of Technology
文摘In this article, the global existence and the large time behavior of smooth solutions to the initial boundary value problem for a degenerate compressible energy transport model are established.
基金This work is supported by the National Key Research and Development Program of China(2018YFA0605702)the National Natural Science Foundation of China(NSFC,41906002,91858210,41976006,and 41776009).
文摘Under external heating forcing in the Southern Ocean,climate models project anomalous northward atmosphere heat transport(AHT)across the equator,accompanied by a southward shift of the intertropical convergence zone(ITCZ).Comparison between a fully coupled and a slab ocean model shows that the inclusion of active ocean dynamics tends to partition the cross-equatorial energy transport and significantly reduce the ITCZ shift response by a factor of 10,a finding which supports previous studies.To understand how ocean dynamics damps the ITCZ’s response to an imposed thermal heating in the Southern Ocean,we examine the ocean heat transport(OHT)and ocean circulation responses in a set of fully coupled experiments.Results show that both the Indo-Pacific and the Atlantic contribute to transport energy across the equator mainly through its Eulerian-mean component.However,different from previous studies that linked the changes in OHT to the changes in the wind-driven subtropical cells or the Atlantic meridional overturning circulation(AMOC),our results show that the cross-equatorial OHT anomaly is due to a broad clockwise overturning circulation anomaly below the subtropical cells(approximately bounded by the 5°C to 20°C isotherms and 50°S to 10°N).Further elimination of the wind-driven component,conducted by prescribing the climatological wind stress in the Southern Ocean heat perturbation experiments,leads to little change in OHT,suggesting that the OHT response is predominantly thermohaline-driven by air-sea thermal interactions.
基金The financial support of this work by the Natural Sciences and Engineering Research Council of Canada is greatfully acknowledged.
文摘Polymers of 1- and 2-vinylnaphthalene containing more than about 50 mol% sulfonic acid groups dissolve in water to form 'hypercoiled' conformations which have many of the properties of micelles. Hydrophobic molecules such as anthracene and perylene are selectively absorbed in these pseudo micellar structures, and their fluorescence emission is sensitized by energy transfer from the surrounding naphthalene chromophores. When irradiated with UV light in the presence of oxygen, the emission of perylene rapidly decreases. It is proposed that this is due to reaction of singlet oxygen with the perylene trapped in the hypercoiled polymer. (Author abstract) 3 Refs.
基金supported by National Natural Science Foundation of China(No.11305070)the Ministry of Science and Technology(No.2013GB106001)the Open Foundation of the Key Laboratory of Geospace Environment,the CSA/SAFEA International Partnership Program for Creative Research Teams
文摘Radial profiles of the ion temperature,Ti,have been measured by a double-sided retarding field analyzer(RFA) in the scrape-off layer(SOL) of the J-TEXT tokamak(R = 105 cm,r = 25-29 cm,Bt = 1.8-2.0 T,Ip = 120-180 kA,ne =(2-2.5) × 10^19 m^-3).Strongly declining Ti profiles in the SOL have been found.The different e-folding lengths,At,of the Ti profiles in two experimental configurations with different magnetic connection lengths,Lc,reveal that a longer Lc results in weaker parallel energy transport and longer At.In similarity with the particle transport across the SOL,At is approximately proportional to the square root of Lc.Additionally,the poloidal asymmetry has been identified with enhanced ion energy transport across the SOL on the low-field side.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0403501)the National Natural Science Foundation of China(Grant No.21873033)the Program for HUST Academic Frontier Youth Team。
文摘We show that a current-carrying coherent electron conductor can be treated as an effective bosonic energy reservoir involving different types of electron–hole pair excitations.For weak electron–boson coupling,hybrid energy transport between nonequilibrium electrons and bosons can be described by a Landauer-like formula.This allows for unified account of a variety of heat transport problems in hybrid electron–boson systems.As applications,we study the non-reciprocal heat transport between electrons and bosons,thermoelectric current from a cold-spot,and electronic cooling of the bosons.Our unified framework provides an intuitive way of understanding hybrid energy transport between electrons and bosons in their weak coupling limit.It opens the way of nonequilibrium reservoir engineering for efficient energy control between different quasi-particles at the nanoscale.
基金supported by the National Natural Science Foundation of China(Grant Nos.11575087 and 11305045)the Fundamental Research Funds for the Central Universities,China(Grant No.2017B17114)
文摘We study the dynamical energy equipartition properties in the integrable Toda model with additional uniform or disordered on-site energies by extensive numerical simulations. The total energy is initially equidistributed among some of the lowest frequency linear modes. For the Toda model with uniform on-site potentials, the energy spectrum keeps its profile nearly unchanged in a relatively short time scale. On a much longer time scale, the energies of tail modes increase slowly with time. Energy equipartition is far away from being attached in our studied time scale. For the Toda model with disordered on-site potentials, the energy transfers continuously to the high frequency modes and eventually towards energy equipartition. We further perform a systematic study of the equipartition time teq depending on the energy density ε and the nonlinear parameter α in the thermodynamic limit for the Toda model with disordered on-site potentials. We find teq∝ (1/ε)^a(1/α)^b, where b≈ 2a. The values of a and b are increased when increasing the strengths of disordered on-site potentials or decreasing the number of initially excited modes.
基金This research is partly supported by project SGS-2019-001The 3-D visualisations were prepared by students of University of West Bohemia or by professional designers.
文摘Land transport can no longer meet the requirements.European transport can be described by these words−crowded motorways and cities,dangerous emissions,ubiquitous traffic accidents,delays,expensive railways.Solutions are being sought to transfer a large part of passengers and especially freight transport to(high-speed)rail,and efforts are moving towards electromobility,car-sharing,5G-connectivity,autonomous driving,MaaS(Mobility as a Service)-coordinated transport or hyperloop-type solutions.However,all these solutions have additional challenges and limitations.Solutions are not being searched where they really exist-in the mutual adaptation of road and rail vehicles and their deep cooperation.The ComplexTrans project shows that simply adapting the dimensions and functions of road and rail vehicles can eliminate(or at least significantly reduce)all the problems of existing land transport.The main features of the ComplexTrans system are sufficient parking spaces,reduction of urban and non-urban congestion,electric vehicles with unlimited range and cheaper than standard cars,cheaper and more accessible battery charging,“autonomous ride”,solving the overlap between passenger and freight rail transport and making it self-financing,transferring intercity freight transport to rail,replacing part of continental air transport and many others.The cost-effective and clustered individual transport and individualised public transport of the ComplexTrans system also bring very significant reductions in the risk of transmission of covid-19 and other contagious diseases during transport.
基金supported by the National Natural Science Foundation of China(Nos.52106099 and 51576004)the Natural Science Foundation of Shandong Province(No.ZR2022YQ57)the Taishan Scholars Program.
文摘Phonon polaritons(PhPs)exhibit directional in-plane propagation and ultralow losses in van der Waals(vdW)crystals,offering new possibilities for controlling the flow of light at the nanoscale.However,these PhPs,including their directional propagation,are inherently determined by the anisotropic crystal structure of the host materials.Although in-plane anisotropic PhPs can be manipulated by twisting engineering,such as twisting individual vdW slabs,dynamically adjusting their propagation presents a significant challenge.The limited application of the twisted bilayer structure in bare films further restricts its usage.In this study,we present a technique in which anisotropic PhPs supported by bare biaxial vdW slabs can be actively tuned by modifying their local dielectric environment.Excitingly,we predict that the iso-frequency contour of PhPs can be reoriented to enable propagation along forbidden directions when the crystal is placed on a substrate with a moderate negative permittivity.Besides,we systematically investigate the impact of polaritonic coupling on near-field radiative heat transfer(NFRHT)between heterostructures integrated with different substrates that have negative permittivity.Our main findings reveal that through the analysis of dispersion contour and photon transmission coefficient,the excitation and reorientation of the fundamental mode facilitate increased photon tunneling,thereby enhancing heat transfer between heterostructures.Conversely,the annihilation of the fundamental mode hinders heat transfer.Furthermore,we find the enhancement or suppression of radiative energy transport depends on the relative magnitude of the slab thickness and the vacuum gap width.Finally,the effect of negative permittivity substrates on NFRHT along the[001]crystalline direction ofα-MoO3 is considered.The spectral band where the excited fundamental mode resulting from the negative permittivity substrates is shifted to the first Reststrahlen Band(RB 1)ofα-MoO_(3) and is widened,resulting in more significant enhancement of heat flux from RB 1.We anticipate our results will motivate new direction for dynamical tunability of the PhPs in photonic devices.
基金made to the Donors of the American Chemical Society Petroleum Research Fund for support of this research(Grant 52043-UR5)
文摘Liquid marbles (non-stick droplets) containing crude petroleum are reported. Liquid marbles were ob- tained by use of fluorinated decyl polyhedral oligomeric silsequioxane (FD-POSS) powder. Marbles containing crude petroleum remained stable on a broad diversity of solid and liquid supports. The effective surface tension of marbles filled with petroleum was established. The mechanism of friction of the marbles is discussed. Actuation of liquid marbles containing crude petroleum with an electric field is presented.
基金the State Key Program of National Natural Science of China under Grant No. 51138001Science Fund for Creative Research Groups of the National Natural Science Foundation of China under Grant No. 51121005Open Research Fund Program of State key Laboratory of Hydro science and Engineering under Grant No. shlhse-2010-C-03
文摘Based on the formulation of a multiple non-isotropic scattering process, a characteristic source time is introduced to define the initial impulse width of energy density at the source. An analytical expression of the initial intensity spectral density of a seismic wave is incorporated into the integral equation of seismic wave energy density. And, a recursive formula of Green's function is derived to obtain the higher order Green's function, which is included to describe the stronger non-isotropic scattering process. Then, the effect of the scattering pattern on the energy density envelope is investigated by the modified scattering theory. Significant differences arc found in the decay of the energy density envelopes with distances using different scattering patterns. The envelope synthesized by the forward dominated scattering pattern is larger than the results obtained by the isotropic and backward dominated scattering pattern. Different scattering patterns are also used to fit the observation data from the aftershocks of the 2008 Wenchuan earthquake. It is concluded that the envelopes synthesized by the forward scattering pattern can match the data better than the isotropic and backward dominated scattering cases, and a new interpretation of the coda wave is given. Finally, using the forward dominated scattering pattern, the envelope broadening of the observed data is reproduced.
文摘The thermal stability of the soliton excited in the protein molecular system which work at finite temperature and a nonlinear vibration of the molecular chain have beed studied in our theory. The results obtained show that the soliton moves in supersonic velocity and the amplitude of soliton depends on the temperature and the strengthen of nonlinear vibration. but the soliton excited is thermal stable in the case of the physiologic temperature 310K.
基金supported by National Natural Science Foundation of China(Grant No.51337006)
文摘The current interruption capability of a gas, when used in high voltage gas-blast circuit breakers,depends not only on its material properties but also the flow field since turbulence plays a dominant role in arc cooling during the interruption process. Based on available experimental results, a study of CO2 switching arcs under a DC(direct current) current in the model circuit breaker has been conducted to calibrate CO2 arc model and to analyse its electric and thermal property. Through detailed analysis of the results mechanisms responsible for the temperature distribution are identified and the domain energy transportation process of different region discussed. The present work provides significant coefficients for CO2 switching arc simulation and gives a better understanding of CO2 arc burning mechanisms.
文摘This work aims to investigate the factors accelerating electric vehicle(EV)acceptance at the consumer end in Pakistan and analyzes the implications for policymakers for a fast-track EV transition.The study further in-vestigates the high EV penetration scenario resulting from the technology acceptance model(TAM's 80%EV)and its impact on energy demand and CO_(2)emissions.The study design used a quantitative analysis method with the survey as an instrument for data collection regarding EV acceptance.The model under investigation was adapted from the famous Technology-Acceptance Models(TAMs)and modified with other significant predictors evidenced in the literature.Correlation and stepwise regression were performed with a multicollinearity check for model hypothesis testing.Out of six predictors,only four factors were significant in accelerating the EV transition.Financial policies were found to be highly significant,followed by environmental concern,facilitating conditions and perceived ease of use.The research then used exponential smoothing forecasts for transport demand and developed an EV penetration scenario based on modified TAM results.The results highlight the significant in-crease in transport demand and the opportunity for Pakistan to limit passenger transport emissions to 36.6 MT instead of 61.6 MT by 2040.
基金supported by the National Natural Science Foundation of China (31261140363, 31171230)the National Basic Research and Development Program (2010CB126601)+1 种基金China Agriculture Research System (CARS-12wwq)the Hainan Province Innovative Research Team Foundation (2016CXTD013)
文摘Cassava is a staple food, feed and bioenergy crop important to the world especially in the tropics.Domesticated cassava is characterized by powerful carbohydrate accumulation but its wild progenitor is not.Here, we investigated the transcriptional differences of eight c DNA libraries derived from developing leaf, stem and storage root of cassava cv. Arg7 and an ancestor line,W14, using next generation sequencing system. A total of41302 assembled transcripts were obtained and from these,25961 transcripts with FPKM≥3 in at least one library were named the expressed genes. A total of 2117, 1963 and3584 transcripts were found to be differentially expressed in leaf, stem and storage root(150 d after planting),respectively, between Arg7 and W14 and ascribed to 103,93 and 119 important pathways in leaf, stem and storage root, respectively. The highlight of this work is that the genes involved in light response, such as those for photosystem I(PSA) and photosystem II(PSB), other genes involved in light harvesting, and some of the genes in the Calvin cycle of carbon fixation were specially upregulated in leaf. Genes for transport and also for key rate-limiting enzymes(PFK, PGK and PK, GAPDH)coupling ATP consumption in glycolysis pathway were predominantly expressed in stem, and genes for sucrose degradation(INVs), amylose synthesis(GBSS) and hydrolysis(RCP1, AMYs), the three key steps of starch metabolism, and transport associated with energy translocation(ABC, AVPs and ATPase) and their upstream transcription factors had enhanced expression in storage root in domesticated cassava. Co-expression networks among the pathways in each organs revealed therelationship of the genes involved, and uncovered some of the important hub genes and transcription factors targeting genes for photosynthesis, transportation and starch biosynthesis.
文摘The role of interface couplings on the energy transport of two coupled Frenkel-Kontorova (FK) chains is explored through numerical simulations. In general, it is expected that the interface cou- plings result in the suppression of heat conduction through the coupled system due to the additional interface phonon-phonon scattering. In the present paper, it is found that the thermal conductivity increases with increasing intensity of interface interactions for weak inter-chain couplings, whereas the heat conduction is suppressed by the interface interaction in the case of strong inter-chain couplings. Based on the phonon spectral energy density method, we demonstrate that the enhance- ment of energy transport results from the excited phonon modes (in addition to the intrinsic phonon modes), while the strong interface phonon-phonon scattering results in the suppressed energy transport.
基金supported by the National Natural Science Foundation of China (Grant No. 41821003)。
文摘We use 9 years data of Cluster to study the dependencies of plasma parameters and energy transport in the plasma sheet on the lasting time of northward/southward interplanetary magnetic field(IMF). The plasma parameters and energy transport in the plasma sheet always respond to the change of IMF direction by more or less time. The ion density starts to increase/decrease remarkably at 80 min after northward/southward IMF turning. The ion temperature starts to decrease at 25 min after northward IMF turning, whereas it starts to increase at 80 min after southward IMF turning. The earthward convection velocity within15 min after northward IMF turning almost equals to that within 15 min period after southward IMF turning. However at time greater than 15 min after southward IMF turning, the earthward convection velocity under southward IMF starts to remarkably increase. The response time(15 min) of magnetospheric convection velocity is well consistent with the response times of nightside ionospheric convection to southward IMF turning. The enthalpy flux is larger than kinetic flux by about three orders of magnitudes, and thus the enthalpy flux plays a dominant role in the plasma sheet energy transport. The enthalpy flux does not weaken immediately after northward IMF turning. The enthalpy flux within 15 min after northward IMF turning is comparable to or even slightly larger than that within 15 min after southward IMF. The enthalpy flux starts to decrease at times greater than15 min after northward IMF turning, whereas it starts to increase at times greater than 15 min after southward IMF turning. The result that the enhanced energy transport during the 15 min period after northward IMF turning may explain previous observation that substorms frequently occur shortly after northward IMF turning.
基金Project supported by the National Natural Science Foundation of China(No.50902012)the Natural Science Foundation of Sichuan Province,China(No.2009JY0087)
文摘Lead iodide single crystal was grown by physical vapor transport method.Two radiation detectors with different configurations were fabricated from the as-grown crystal.The electrical and y-ray response properties at room temperature of the both detectors were investigated.It is found that the dark resistivity of the detectors are respectively 3×10^(10)Ω·cm for bias electric field parallel to crystal c-axis(E//c) and 2×10~8Ω·cm for perpendicular to crystal c-axis(E⊥c).The energy spectrum response measurement shows that both detectors were sensitive to ^(241) Am 59.5 keVγ-rays,and achieved a good energy resolution of 16.8%for the E⊥c-axis configuration detector with a full width at half maximum of 9.996 keV.
基金the support from the National Basic Research Program of China(No.613322)the Beijing Nova Program,China(No.Z200002121078)+1 种基金the National Natural Science Foundation of China(No.52202506)the Chinese Government Scholarship(CN)(No.201904980001)。
文摘As a key technology for space-based Earth observation and astronomical exploration,cooled mid-wavelength and long-wavelength Infrared(IR)detection is widely used in national defense,astronomy exploration,medical imaging,environmental monitoring,agricultural and other areas.The performances of IR detectors,including cut-off wavelength,detectivity,sensitivity and temperature resolution,plays a significant role in efficiently observing and tracking the low-temperature far-distance moving targets.Achieving optimal detection performance requires the IR detectors to operate at cryogenic temperatures.The future development of space-based applications relies heavily on the mid-wavelength and long-wavelength IR detection technologies,which should be enabled by the long-life cryogenic refrigeration and high-efficiency energy transportation system operating below 40 K,to support the Earth observation and astronomical detection.However,the efficiency degradation caused by the super low temperature brings tremendous challenges to the life time of cryogenic refrigeration and energy transportation systems.This paper evaluates the influence of cryogenic temperature on the infrared detector performances,reviews the features,development and space applications of cryogenic cooling technologies,as well as the cryogenic energy transportation approaches.Additionally,it analyzes the future development trends and challenges in supporting the space-based IR detection.