The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence...The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence is still lacking.To validate this framework,here we employ a programmable robotic platform,where a single light-controlled wheeled robot travels in an activity landscape.Our experiments quantitatively demonstrate that the intrinsic pressure difference across the activity interface is balanced by the emerged polarization force.This result unambiguously confirms the theoretical predictions,thus validating the intrinsic pressure framework and laying the experimental foundation for the intrinsic pressure-based mechanical description of dry active matter.展开更多
The physics of ionic and electrical conduction at electrode materials of lithium-ion batteries （LIBs） are briefly sum marized here, besides, we review the current research on ionic and electrical conduction in elect...The physics of ionic and electrical conduction at electrode materials of lithium-ion batteries （LIBs） are briefly sum marized here, besides, we review the current research on ionic and electrical conduction in electrode material incorporating experimental and simulation studies. Commercial LIBs have been widely used in portable electronic devices and are now developed for large-scale applications in hybrid electric vehicles （HEV） and stationary distributed power stations. However, due to the physical limits of the materials, the overall performance of today＇s LIBs does not meet all the requirements for future applications, and the transport problem has been one of the main barriers to further improvement. The electron and Li-ion transport behaviors are important in determining the rate capacity of LIBs.展开更多
A laboratory experiment was conducted inside a wind wave tank to investigate the wave induced turbulence. In this experiment, the wave surface elevation and velocity beneath the water surface were measured simultaneou...A laboratory experiment was conducted inside a wind wave tank to investigate the wave induced turbulence. In this experiment, the wave surface elevation and velocity beneath the water surface were measured simultaneously to investigate the relation between the wave status and wave induced turbulence. The profile of the turbulent dissipation rate and Reynolds stress were calculated using experimental data. The effect of the wave status on turbulence is investigated with regard to the wind wave, swell, and mixed wave conditions. It was depicted that the turbulence decreased with increasing depth from the water surface and that the turbulence that was induced by a wave with larger wavelength and wave height is much stronger for the same wave status. Finally, we observed that the wind wave is more effective in activating the wave induced turbulence.展开更多
Explicit structure-preserving geometric particle-in-cell(PIC)algorithm in curvilinear orthogonal coordinate systems is developed.The work reported represents a further development of the structure-preserving geometric...Explicit structure-preserving geometric particle-in-cell(PIC)algorithm in curvilinear orthogonal coordinate systems is developed.The work reported represents a further development of the structure-preserving geometric PIC algorithm achieving the goal of practical applications in magnetic fusion research.The algorithm is constructed by discretizing the field theory for the system of charged particles and electromagnetic field using Whitney forms,discrete exterior calculus,and explicit non-canonical symplectic integration.In addition to the truncated infinitely dimensional symplectic structure,the algorithm preserves exactly many important physical symmetries and conservation laws,such as local energy conservation,gauge symmetry and the corresponding local charge conservation.As a result,the algorithm possesses the long-term accuracy and fidelity required for first-principles-based simulations of the multiscale tokamak physics.The algorithm has been implemented in the Sym PIC code,which is designed for highefficiency massively-parallel PIC simulations in modern clusters.The code has been applied to carry out whole-device 6 D kinetic simulation studies of tokamak physics.A self-consistent kinetic steady state for fusion plasma in the tokamak geometry is numerically found with a predominately diagonal and anisotropic pressure tensor.The state also admits a steady-state subsonic ion flow in the range of 10 km s-1,agreeing with experimental observations and analytical calculations Kinetic ballooning instability in the self-consistent kinetic steady state is simulated.It is shown that high-n ballooning modes have larger growth rates than low-n global modes,and in the nonlinear phase the modes saturate approximately in 5 ion transit times at the 2%level by the E×B flow generated by the instability.These results are consistent with early and recent electromagnetic gyrokinetic simulations.展开更多
The altimeter normalized radar cross section(NRCS) has been used to retrieve the sea surface wind speed for decades, and more than a dozen of wind speed retrieval algorithms have been proposed. Despite the continuing ...The altimeter normalized radar cross section(NRCS) has been used to retrieve the sea surface wind speed for decades, and more than a dozen of wind speed retrieval algorithms have been proposed. Despite the continuing efforts to improve the wind speed measurements, a bias dependence on wave state persists in all wind algorithms. On the basis of recent evidence that short waves are essentially modulated by local winds and much less affected by wave state, we proposed a physics-based approach to retrieve the wind speed from the dual-frequency difference in terms of the mean square slope of short waves. A collocated dataset of coincident altimeter/buoy measurements were used to develop and validate the approach. Validation against buoy measurements indicates that the approach is almost unbiased and has an overall root mean square error of 1.24 m s-1, which is 5.3% lower than the single-parameter algorithm in operational use(Witter and Chelton, 1991) and 2.4% lower than another dual-frequency approach(Chen et al., 2002). Furthermore, the results indicate that the new approach significantly improves the wave-dependent bias compared to the single-parameter algorithm. The capacity of altimeter to retrieve sea surface wind speed appears to be limited for the case of winds below 3 m s-1. The validity of the approach at high winds needs to be further examined in the future study.展开更多
Due to advantages of high power-conversion efficiency(PCE), large power-to-weight ratio(PWR), low cost and solution processibility, flexible perovskite solar cells(f-PSCs) have attracted extensive attention in recent ...Due to advantages of high power-conversion efficiency(PCE), large power-to-weight ratio(PWR), low cost and solution processibility, flexible perovskite solar cells(f-PSCs) have attracted extensive attention in recent years. The PCE of f-PSCs has developed rapidly to over 25%, showing great application prospects in aerospace and wearable electronic devices. This review systematically sorts device structures and compositions of f-PSCs, summarizes various methods to improve its efficiency and stability recent years. In addition, the applications and potentials of f-PSCs in space vehicle and aircraft was discussed. At last, we prospect the key scientific and technological issues that need to be addressed for f-PSCs at current stage.展开更多
ZrCoRE(RE denotes rare earth elements)non-evaporable getter films have significant applications in vacuum packaging of micro-electro mechanical system devices because of their excellent gas adsorption performance,low ...ZrCoRE(RE denotes rare earth elements)non-evaporable getter films have significant applications in vacuum packaging of micro-electro mechanical system devices because of their excellent gas adsorption performance,low activation temperature and environmental friendliness.The films were deposited using DC magnetron sputtering with argon and krypton gases under various deposition pressures.The effects of sputtering gas type and pressure on the morphology and hydrogen adsorption performance of ZrCoRE films were investigated.Results show that the films prepared in Ar exhibit a relatively dense structure with fewer grain boundaries.The increase in Ar pressure results in more grain boundaries and gap structures in the films.In contrast,films deposited in Kr display a higher density of grain boundaries and cluster structures,and the films have an obvious columnar crystal structure,with numerous interfaces and gaps distributed between the columnar structures,providing more paths for gas diffusion.As Kr pressure increases,the film demonstrates more pronounced continuous columnar structure growth,accompanied by deeper and wider grain boundaries.This structural configuration provides a larger specific surface area,which significantly improves the hydrogen adsorption speed and capacity.Consequently,high Ar and Kr pressures are beneficial to improve the adsorption performance.展开更多
Nitrogen doping in chemical vapor deposition-derived ultrananocrystalline diamond(UNCD)films in-creases the electronic conductivity,yet its microstructural effects on electron transport are insufficiently understood.W...Nitrogen doping in chemical vapor deposition-derived ultrananocrystalline diamond(UNCD)films in-creases the electronic conductivity,yet its microstructural effects on electron transport are insufficiently understood.We investigated the formation of nitrogen-induced diaph-ite structures(hybrid diamond-graphite phases)and their role in changing the conductivity.Nitrogen doping in a hy-drogen-rich plasma environment promotes the emergence of unique sp^(3)-sp^(2)bonding interfaces,where diamond grains are covalently integrated with graphitic domains,facilitating a structure-driven electronic transition.High-resolution transmis-sion electron microscopy and selected area electron diffraction reveal five-fold,six-fold and twelve-fold symmetries,along with an atypical{200}crystallographic reflection,confirming diaphite formation in 5%and 10%N-doped UNCD films,while high-er doping levels(15%and 20%)result in extensive graphitization.Raman spectroscopy tracks the evolution of sp^(2)bonding with increasing nitrogen content,while atomic force microscopy and X-ray diffraction indicate a consistent diamond grain size of~8 nm.Cryogenic electronic transport measurements reveal a conductivity increase from 8.72 to 708 S/cm as the nitrogen dop-ing level increases from 5%to 20%,which is attributed to defect-mediated carrier transport and 3D weak localization.The res-ulting conductivity is three orders of magnitude higher than previously reported.These findings establish a direct correlation between diaphite structural polymorphism and tunable electronic properties in nitrogen-doped UNCD films,offering new ways for defect-engineering diamond-based electronic materials.展开更多
We introduce a hybrid cavity optomechanical model capable of generating significant genuine tripartite interactions and entanglement among coherent degrees of freedom.However,realizing and controlling such tripartite ...We introduce a hybrid cavity optomechanical model capable of generating significant genuine tripartite interactions and entanglement among coherent degrees of freedom.However,realizing and controlling such tripartite interactions and their entanglement pose crucial challenges that remain largely unexplored.In this work,we predict a tripartite coupling mechanism within a hybrid quantum system consisting of a vibrating mechanical oscillator,a two-level atom and a singlefrequency cavity field.We specifically propose a mechanism for tripartite and cross-Kerr nonlinear coupling through displacement and squeezing transformations.By adjusting the optical amplitude of the pump light,we can effectively enhance these nonlinear couplings,facilitating the manipulation of entangled and squeezed states.The resulting tripartite genuine entanglement exhibits distinct evolutionary characteristics.Notably,when the pump light amplitude is large,the tripartite entanglement persists for longer time.Additionally,the phonon displays characteristics of both cooling and squeezing.Our study presents a pathway for exploring and exploiting controllable multipartite entanglement,as well as achieving phonon cooling and squeezing with the assistance of a mesoscopic harmonic oscillator.This work underscores the innovative potential of our model in advancing the field of optomechanics and quantum entanglement.展开更多
Mesoscale eddies play a central role in the poleward oceanic heat flux in the Southern Ocean.Previous studies have documented changes in the location of temperature fronts in the Southern Ocean,but little attention ha...Mesoscale eddies play a central role in the poleward oceanic heat flux in the Southern Ocean.Previous studies have documented changes in the location of temperature fronts in the Southern Ocean,but little attention has been paid to changes in the genesis locations of mesoscale eddies.Here,we provide evidence from three decades of satellite altimetry observations for the heterogeneity of the poleward shift of mesoscale activities,with the largest trend of~0.23°±0.05°(10 yr)^(-1) over the Atlantic sector and a moderate trend of~0.1°±0.03°(10 yr)^(-1) over the Indian sector,but no significant trend in the Pacific sector.The poleward shift of mesoscale eddies is associated with a southward shift of the local westerly winds while being constrained by the major topographies.As the poleward shift of westerly winds is projected to persist,the poleward oceanic heat flux from mesoscale eddies may influence future ice melt.展开更多
Infrared-transparent conductors have attracted considerable attention due to their potential applications in electromagnetic shielding,infrared sensors,and photovoltaic devices.However,most known materials face the cr...Infrared-transparent conductors have attracted considerable attention due to their potential applications in electromagnetic shielding,infrared sensors,and photovoltaic devices.However,most known materials face the critical challenge of balancing high infrared transmittance with high electrical conductivity across the broad infrared spectral band(2.5-25μm).While ultra-thin indium tin oxide(ITO)films have been demonstrated to exhibit superior infrared transmittance,their inherent low electrical conductivity necessitates additional enhancement strategies.This study systematically investigates the effects of oxygen vacancy concentration regulation and ultra-thin copper capping layer integration on the infrared optoelectronic properties of 20 nm-thick ITO films.A fundamental trade-off is revealed in ITO films that increased oxygen vacancy content enhances the electrical conductivity while compromising the infrared transmittance.Meanwhile,following the introduction of a Cu capping layer,the Cu/ITO system exhibits opposing dependencies of infrared transmittance and electrical conductivity on the capping layer thickness,with an optimum thickness of~3 nm.Finally,by constructing a Cu(3 nm)/ITO(20 nm)heterostructure with varying oxygen vacancy content,we demonstrate the combined effect of the ultra-thin Cu capping layer and moderate oxygen vacancy content on optimizing the carrier transport network.This configuration simultaneously minimizes surface/interfacial reflection and absorption losses,achieving high infrared transmittance(0.861)and a low sheet resistance of 400 W/sq.Our findings highlight the critical role of the combined effect of metal/oxide heterostructure design and defect engineering in optimizing infrared-transparent conductive properties.展开更多
To address the future application requirements of carbon-based material grids for ion thrusters characterized by high thrust,elevated specific impulse,and extended operational life,research was conducted using the LIP...To address the future application requirements of carbon-based material grids for ion thrusters characterized by high thrust,elevated specific impulse,and extended operational life,research was conducted using the LIPS-100 ion thruster developed by the Lanzhou Institute of Physics.This study focused on small-diameter configurations of carbon-carbon composite material grids.Successful development was achieved for both a 10 cm split carbon-carbon planar grid and an integrated carbon-carbon convex grid component.Performance variations among different configurations were investigated through extensive performance tests across the wide-range from 1 to 25 mN,as well as 200 h lifespan assessments under typical conditions at 20 mN.The results indicate that the two configurations of the carbon-carbon grid can achieve stable operation across the broad range of 1-20 mN,with beam current fluctuations ranging from 368 to 379 mA and accel grid current fluctuations between 1.58 and 1.81 mA.Furthermore,the key performance parameters of these grids were comparable to those of the traditional molybdenum grids.Under conditions of high thrust and power,the carbon-carbon grid demonstrated a significant reduction in the intercepted current at the accel grid.In comparison to the split carbon-carbon planar grid,the weight of the integrated carbon-carbon convex composite grid was reduced by 17.5%,the anode voltage decreased by approximately 2.4%-8.6%,and the cathode keeper voltage was reduced by approximately 3.5%-12.4%.It can be concluded that the integrated carbon-carbon convex grid offers distinct advantages in terms of hot-state structural stability,suppression of grid etching rates,and enhancement of thruster discharge efficiency.展开更多
A 100-channel double-foil soft X-ray array imaging(DSXAI)diagnostic system has been developed for the HL-2A tokamak to obtain tomographic bremsstrahlung emissivity and electron temperature(T_(e)).This system employs a...A 100-channel double-foil soft X-ray array imaging(DSXAI)diagnostic system has been developed for the HL-2A tokamak to obtain tomographic bremsstrahlung emissivity and electron temperature(T_(e)).This system employs a double-foil technique to determine T_(e) by comparing the soft X-ray(SXR)emissivities from the same plasma location through two beryllium(Be)foils of differing thickness.The DSXAI system comprises five photocameras mounted at two different poloidal cross-sections,separated toroidally by 15°,allowing for three distinct poloidal viewing angles.Each photocamera features 20 channels,offering a temporal resolution of approximately 4μs and a spatial resolution of about 8 cm,with no channel overlap.Each photocamera contains two identical optical systems,each defined by an aperture slit and a photodiode array.The double-foil configuration is realized by placing these two optical systems,each with a different Be foil,in close proximity.Initial experimental results demonstrate that the DSXAI diagnostic system performs well,successfully reconstructing 2-dimensional(2D)tomographic SXR emissivity and T_(e) on the HL-2A tokamak.This study provides valuable insights for the future implementation of similar diagnostic systems on fusion reactors like ITER.展开更多
In this research work, atomic and molecular orbitals based analysis has been made to see electronic structure of platinum halides (platinum dichloride, platinum dibromide, platinum diiodide and platinum difluride). Th...In this research work, atomic and molecular orbitals based analysis has been made to see electronic structure of platinum halides (platinum dichloride, platinum dibromide, platinum diiodide and platinum difluride). The geometry optimization and three dimensional (3D) modeling of the above mentioned species have been made on CAChe pro software. The results show: (i) The involvement of three p atomic orbitals is negligible as their summation values are very low in comparison to d orbital and considerably low with respect to s orbital. (ii) The study well support the Landis concepts of sdn-hybridation (here n = 1) as bond angle and contributions of s-orbital and d-orbital of Pt(II) are maximum with negligible contribution of p-orbitals. (iii) These halides also support the cloud-expanding effect with experimental data and also follow the nephelauxetic effect. The result is in good agreement with experiment results that covalent character increases in the order: PtI2 > PtBr2 > PtCl2 > PtF2. (iv) And thus the study will help to fine tune the existing complexes of these halides.展开更多
The accurate simulation of wave propagation in real media requires properly taking the attenuation into account,which leads to wave dissipation together with its causal companion,wave dispersion.In this study,to obtai...The accurate simulation of wave propagation in real media requires properly taking the attenuation into account,which leads to wave dissipation together with its causal companion,wave dispersion.In this study,to obtain a weak formulation of heterogenous viscoacoustic wave propagation in an infinite domain,the viscoacoustic medium is first characterized by its frequency-dependent complex bulk compliance instead of the classically used complex bulk modulus.Then,a mechanical model using serially connected standard linear solids(SSLS)is built to obtain the rational approximation of the complex bulk compliance whose parameters are calculated via an adapted nonlinear optimization method.Utilizing the obtained bulk compliance-based constitutive relation,a novel second-order viscoacoustic wave equation in the frequency domain is derived,of which the weak formulation can be physically explained as the virtual work equation and can thus be discretized using a continuous spectral element method in space.Additionally,a new method is introduced to address the convolution terms involved in the inverse Fourier transform,whose accurate time integration can then be achieved using an explicit time scheme,which avoids the transient growth that exists in the classical method.The resulting full time-space decoupling scheme can handle wave propagation in arbitrary heterogeneous media.Moreover,to treat the wave propagation in an infinite domain,a perfectly matched layer in weak formulation is derived for the truncation of the infinite domain via complex coordinate stretching of the virtual work equation.With only minor modification,the resulting perfectly matched layer can be implemented using the same time scheme as for the wave equation inside the truncated domain.The accuracy,numerical stability,and versatility of the new proposed scheme are demonstrated with numerical examples.展开更多
Mesoscale air-sea interactions play a critical role in damping eddy activities.However,how mesoscale heat flux influences the distribution of eddy kinetic energy(EKE)in the wavenumber space remains unclear.In this stu...Mesoscale air-sea interactions play a critical role in damping eddy activities.However,how mesoscale heat flux influences the distribution of eddy kinetic energy(EKE)in the wavenumber space remains unclear.In this study,we investigate the EKE and temperature variance(T_(var))budgets in the Kuroshio Extension(KE)region using wavenumber spectral analysis based on 1/10°coupled climate simulations.These simulations include a standard high-resolution simulation and a smoothed simulation that overlooks mesoscale heat flux.By comparing the differences between these models,we confirm that air-sea heat exchange significantly dissipates Tvar.Neglecting mesoscale heat flux results in a 60% underestimation of the Tvar damping rate,which in turn increases energy transfer to EKE through the vertical buoyancy flux by 22%.This enhanced vertical buoyancy flux leads to a 20% higher EKE level and larger energy budget terms,particularly in the diffusion term,which is closely related to wind power.Furthermore,underestimating air-sea heat exchange could lead to an overestimation of the inverse kinetic energy cascade,thereby distorting the overall energy budget in the KE region.展开更多
Thefield of energy storage devices is primarily dominated by lithium-ion batteries(LIBs)due to their mature manufacturing processes and stable performance.However,immature lithium recovery technology cannot stop the co...Thefield of energy storage devices is primarily dominated by lithium-ion batteries(LIBs)due to their mature manufacturing processes and stable performance.However,immature lithium recovery technology cannot stop the continuous increase in the cost of LIBs.Along with the rapid development of electric transportation,it has become inevitable to trigger a new round of competition in alternative energy storage systems.Some monovalent rechargeable metal ion batteries(sodium ion batteries(SIBs)and potassium ion batteries(PIBs),etc.)and multi-valent rechargeable metal-ion batteries(magnesium ion batteries(MIBs),calcium ion batteries(CIBs),zinc ion batteries(ZIBs),and aluminum ion batteries(AIBs),etc.)are potential candidates,which can replace LIBs in some of the scenarios to alleviate the pressure on supply.The cathode material plays a crucial role in determining the battery capacity.Transition metal compounds dominated by layered transition metal oxides as key cathode materials for secondary batteries play an important role in the advancement of various battery energy storage systems.In summary,this manuscript aims to review and summarize the research progress on transition metal compounds used as cathodes in different metal ion batteries,with the aim of providing valuable guidance for the exploration and design of high-performance integrated battery systems.展开更多
Bi(Sb)_(2)Te(Se)_(3)alloys,as the only commercial thermoelectric materials,have been applied widely in cooling fields.While,the current energy conversion efficiency(dominated by the dimensionless ZT)of commercial prod...Bi(Sb)_(2)Te(Se)_(3)alloys,as the only commercial thermoelectric materials,have been applied widely in cooling fields.While,the current energy conversion efficiency(dominated by the dimensionless ZT)of commercial products is still lower and cannot meet the market demand.In this paper,high thermoelectric performance at room temperature in both zonemelted(ZM)Bi_(0.46)Sb_(1.54)Te_(3)ingots and powder-metallurgy(PM)Bi_(0.46)Sb_(1.54)Te_(3)blocks with a large size was realized successfully by optimizing their preparation process.The peak ZT values of ZM and PM p-type Bi_(0.46)Sb_(1.54)Te_(3)alloys reached 1.26 and 1.45,respectively.They are higher than those of all the n-type or p-type Bi_(2)Te_(3)-based products in current commercial applications.In particular,their production process of large size p-type Bi_(0.46)Sb_(1.54)Te_(3)alloys could be directly industrialized.展开更多
Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems...Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems is still a challenging problem that needs to be solved,as it affects reliability.Based on the analysis of in-orbit and ground test data of ion thrusters from simulation and experimental results,the main influencing factors of induced electric breakdown are clarified and the mechanisms of induced electric breakdown are analyzed.It is found that the main factors inducing breakdown are the voltage and electric field strength between the grids.In addition,by monitoring the waveform of plasma discharge,the temporal characteristics of breakdown can be defined as three stages of“breakdown-spark-loop response”.Thus,three kinds of engineering suppression methods for breakdown of static vacuum with periodic short-term heating,electrode surface polishing and sealing insulation with plasma,add energy suppression circuit are carried out,and the experimental results show that the electric breakdown frequency can be reduced by about 30%.展开更多
The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions ...The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions across 14 summers from 1999 to 2022.In austral summer,the mCDW upwells along the upper continental slope then intrudes on the continental shelf across the shelf break in a warm tongue that gradually upwells poleward.The mCDW intrusion at the 73°E section is relatively weaker in December and stronger in February while showing significant interannual variability.During strong intrusions(January 2000 and February 2003),the mCDW extends southward to 68°S and upwells to 50 m,whereas the mCDW only reaches the shelf break during weak intrusions(December 2004,January 2006,January 2011,and February 2015).The intensity of the mCDW intrusions correlates strongly with the accumulated wind stress curl(30 days prior)north of the shelf break(73.5°-78.0°E,64.5°-66.0°S).The summertime westerly winds play a key role in regulating the interannual variability of mCDW intrusion onto the continental shelf.A southward shift of the westerly winds promotes the upwelling and southward intrusion of mCDW across the shelf break.In addition,mCDW at 73°E can reach as far as 68°S due to the southward flow of mCDW being hindered by a northward outflowing branch of the coastal current at the Amery Ice Shelf(AIS)front.In austral summer,the mCDW had never been observed at the section along the AIS front;thus,it cannot directly contribute to the basal melting of the ice shelf.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.T2325027,12274448,T2350007,12404239,12174041,12325405,12090054,and T2221001)the National Key R&D Program of China (Grant No.2022YFF0503504)。
文摘The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence is still lacking.To validate this framework,here we employ a programmable robotic platform,where a single light-controlled wheeled robot travels in an activity landscape.Our experiments quantitatively demonstrate that the intrinsic pressure difference across the activity interface is balanced by the emerged polarization force.This result unambiguously confirms the theoretical predictions,thus validating the intrinsic pressure framework and laying the experimental foundation for the intrinsic pressure-based mechanical description of dry active matter.
基金supported by the National High Technology Research and Development Program of China(Grant No.2015AA034201)the National Natural Science Foundation of China(Grant Nos.11234013 and 11264014)+2 种基金the Natural Science Foundation of Jiangxi Province,China(Grant Nos.20133ACB21010 and20142BAB212002)the Foundation of Jiangxi Education Committee,China(Grant Nos.GJJ14254 and KJLD14024)supported by the"Gan-po talent 555"Project of Jiangxi Province,China
文摘The physics of ionic and electrical conduction at electrode materials of lithium-ion batteries （LIBs） are briefly sum marized here, besides, we review the current research on ionic and electrical conduction in electrode material incorporating experimental and simulation studies. Commercial LIBs have been widely used in portable electronic devices and are now developed for large-scale applications in hybrid electric vehicles （HEV） and stationary distributed power stations. However, due to the physical limits of the materials, the overall performance of today＇s LIBs does not meet all the requirements for future applications, and the transport problem has been one of the main barriers to further improvement. The electron and Li-ion transport behaviors are important in determining the rate capacity of LIBs.
基金supported by the National Natural Science Foundation of China(No.41276010)the Ministry of Education of China(No.20130132130002)
文摘A laboratory experiment was conducted inside a wind wave tank to investigate the wave induced turbulence. In this experiment, the wave surface elevation and velocity beneath the water surface were measured simultaneously to investigate the relation between the wave status and wave induced turbulence. The profile of the turbulent dissipation rate and Reynolds stress were calculated using experimental data. The effect of the wave status on turbulence is investigated with regard to the wind wave, swell, and mixed wave conditions. It was depicted that the turbulence decreased with increasing depth from the water surface and that the turbulence that was induced by a wave with larger wavelength and wave height is much stronger for the same wave status. Finally, we observed that the wind wave is more effective in activating the wave induced turbulence.
基金supported by the the National MCF Energy R&D Program(No.2018YFE0304100)National Key Research and Development Program(Nos.2016YFA0400600,2016YFA0400601 and 2016YFA0400602)+1 种基金National Natural Science Foundation of China(Nos.11905220 and 11805273)supported by the U.S.Department of Energy(DE-AC02-09CH11466)。
文摘Explicit structure-preserving geometric particle-in-cell(PIC)algorithm in curvilinear orthogonal coordinate systems is developed.The work reported represents a further development of the structure-preserving geometric PIC algorithm achieving the goal of practical applications in magnetic fusion research.The algorithm is constructed by discretizing the field theory for the system of charged particles and electromagnetic field using Whitney forms,discrete exterior calculus,and explicit non-canonical symplectic integration.In addition to the truncated infinitely dimensional symplectic structure,the algorithm preserves exactly many important physical symmetries and conservation laws,such as local energy conservation,gauge symmetry and the corresponding local charge conservation.As a result,the algorithm possesses the long-term accuracy and fidelity required for first-principles-based simulations of the multiscale tokamak physics.The algorithm has been implemented in the Sym PIC code,which is designed for highefficiency massively-parallel PIC simulations in modern clusters.The code has been applied to carry out whole-device 6 D kinetic simulation studies of tokamak physics.A self-consistent kinetic steady state for fusion plasma in the tokamak geometry is numerically found with a predominately diagonal and anisotropic pressure tensor.The state also admits a steady-state subsonic ion flow in the range of 10 km s-1,agreeing with experimental observations and analytical calculations Kinetic ballooning instability in the self-consistent kinetic steady state is simulated.It is shown that high-n ballooning modes have larger growth rates than low-n global modes,and in the nonlinear phase the modes saturate approximately in 5 ion transit times at the 2%level by the E×B flow generated by the instability.These results are consistent with early and recent electromagnetic gyrokinetic simulations.
基金supported by the National High Technology Research and Development Program of China (2013 AA09A505)
文摘The altimeter normalized radar cross section(NRCS) has been used to retrieve the sea surface wind speed for decades, and more than a dozen of wind speed retrieval algorithms have been proposed. Despite the continuing efforts to improve the wind speed measurements, a bias dependence on wave state persists in all wind algorithms. On the basis of recent evidence that short waves are essentially modulated by local winds and much less affected by wave state, we proposed a physics-based approach to retrieve the wind speed from the dual-frequency difference in terms of the mean square slope of short waves. A collocated dataset of coincident altimeter/buoy measurements were used to develop and validate the approach. Validation against buoy measurements indicates that the approach is almost unbiased and has an overall root mean square error of 1.24 m s-1, which is 5.3% lower than the single-parameter algorithm in operational use(Witter and Chelton, 1991) and 2.4% lower than another dual-frequency approach(Chen et al., 2002). Furthermore, the results indicate that the new approach significantly improves the wave-dependent bias compared to the single-parameter algorithm. The capacity of altimeter to retrieve sea surface wind speed appears to be limited for the case of winds below 3 m s-1. The validity of the approach at high winds needs to be further examined in the future study.
基金supported by National Natural Science Foundation of China (Grant Nos. 62204104, 42005138, 12274190, 12274189, 62275115)Shandong Province High Education Youth Innovation Team Program (Grant No. 2023KJ210)Science and Technology Program of Yantai (Grant No. 2023JCYJ047)。
文摘Due to advantages of high power-conversion efficiency(PCE), large power-to-weight ratio(PWR), low cost and solution processibility, flexible perovskite solar cells(f-PSCs) have attracted extensive attention in recent years. The PCE of f-PSCs has developed rapidly to over 25%, showing great application prospects in aerospace and wearable electronic devices. This review systematically sorts device structures and compositions of f-PSCs, summarizes various methods to improve its efficiency and stability recent years. In addition, the applications and potentials of f-PSCs in space vehicle and aircraft was discussed. At last, we prospect the key scientific and technological issues that need to be addressed for f-PSCs at current stage.
基金National Natural Science Foundation of China(62171208)Natural Science Foundation of Gansu Province(23JRRA1355)。
文摘ZrCoRE(RE denotes rare earth elements)non-evaporable getter films have significant applications in vacuum packaging of micro-electro mechanical system devices because of their excellent gas adsorption performance,low activation temperature and environmental friendliness.The films were deposited using DC magnetron sputtering with argon and krypton gases under various deposition pressures.The effects of sputtering gas type and pressure on the morphology and hydrogen adsorption performance of ZrCoRE films were investigated.Results show that the films prepared in Ar exhibit a relatively dense structure with fewer grain boundaries.The increase in Ar pressure results in more grain boundaries and gap structures in the films.In contrast,films deposited in Kr display a higher density of grain boundaries and cluster structures,and the films have an obvious columnar crystal structure,with numerous interfaces and gaps distributed between the columnar structures,providing more paths for gas diffusion.As Kr pressure increases,the film demonstrates more pronounced continuous columnar structure growth,accompanied by deeper and wider grain boundaries.This structural configuration provides a larger specific surface area,which significantly improves the hydrogen adsorption speed and capacity.Consequently,high Ar and Kr pressures are beneficial to improve the adsorption performance.
文摘Nitrogen doping in chemical vapor deposition-derived ultrananocrystalline diamond(UNCD)films in-creases the electronic conductivity,yet its microstructural effects on electron transport are insufficiently understood.We investigated the formation of nitrogen-induced diaph-ite structures(hybrid diamond-graphite phases)and their role in changing the conductivity.Nitrogen doping in a hy-drogen-rich plasma environment promotes the emergence of unique sp^(3)-sp^(2)bonding interfaces,where diamond grains are covalently integrated with graphitic domains,facilitating a structure-driven electronic transition.High-resolution transmis-sion electron microscopy and selected area electron diffraction reveal five-fold,six-fold and twelve-fold symmetries,along with an atypical{200}crystallographic reflection,confirming diaphite formation in 5%and 10%N-doped UNCD films,while high-er doping levels(15%and 20%)result in extensive graphitization.Raman spectroscopy tracks the evolution of sp^(2)bonding with increasing nitrogen content,while atomic force microscopy and X-ray diffraction indicate a consistent diamond grain size of~8 nm.Cryogenic electronic transport measurements reveal a conductivity increase from 8.72 to 708 S/cm as the nitrogen dop-ing level increases from 5%to 20%,which is attributed to defect-mediated carrier transport and 3D weak localization.The res-ulting conductivity is three orders of magnitude higher than previously reported.These findings establish a direct correlation between diaphite structural polymorphism and tunable electronic properties in nitrogen-doped UNCD films,offering new ways for defect-engineering diamond-based electronic materials.
基金supported by the National Natural Science Foundation of China(Grant No.12074213)the Natural Science Foundation of Shandong Province(Grant No.ZR2021MA078)the Research Project of the National Key Laboratory(Grant No.KF202004)。
文摘We introduce a hybrid cavity optomechanical model capable of generating significant genuine tripartite interactions and entanglement among coherent degrees of freedom.However,realizing and controlling such tripartite interactions and their entanglement pose crucial challenges that remain largely unexplored.In this work,we predict a tripartite coupling mechanism within a hybrid quantum system consisting of a vibrating mechanical oscillator,a two-level atom and a singlefrequency cavity field.We specifically propose a mechanism for tripartite and cross-Kerr nonlinear coupling through displacement and squeezing transformations.By adjusting the optical amplitude of the pump light,we can effectively enhance these nonlinear couplings,facilitating the manipulation of entangled and squeezed states.The resulting tripartite genuine entanglement exhibits distinct evolutionary characteristics.Notably,when the pump light amplitude is large,the tripartite entanglement persists for longer time.Additionally,the phonon displays characteristics of both cooling and squeezing.Our study presents a pathway for exploring and exploiting controllable multipartite entanglement,as well as achieving phonon cooling and squeezing with the assistance of a mesoscopic harmonic oscillator.This work underscores the innovative potential of our model in advancing the field of optomechanics and quantum entanglement.
基金supported by the National Natural Science Foundation of China(Grant Nos.42230405,42006029)Science and Technology Plan of Liaoning Province(2024JH2/102400061)+1 种基金Dalian Science and Technology Innovation Fund(2024JJ11PT007)Dalian Science and Technology Pro-gram for Innovation Talents of Dalian(2022RJ06).
文摘Mesoscale eddies play a central role in the poleward oceanic heat flux in the Southern Ocean.Previous studies have documented changes in the location of temperature fronts in the Southern Ocean,but little attention has been paid to changes in the genesis locations of mesoscale eddies.Here,we provide evidence from three decades of satellite altimetry observations for the heterogeneity of the poleward shift of mesoscale activities,with the largest trend of~0.23°±0.05°(10 yr)^(-1) over the Atlantic sector and a moderate trend of~0.1°±0.03°(10 yr)^(-1) over the Indian sector,but no significant trend in the Pacific sector.The poleward shift of mesoscale eddies is associated with a southward shift of the local westerly winds while being constrained by the major topographies.As the poleward shift of westerly winds is projected to persist,the poleward oceanic heat flux from mesoscale eddies may influence future ice melt.
基金supported by the National Key R&D Program of China(Grant No.2022YFB3806300).
文摘Infrared-transparent conductors have attracted considerable attention due to their potential applications in electromagnetic shielding,infrared sensors,and photovoltaic devices.However,most known materials face the critical challenge of balancing high infrared transmittance with high electrical conductivity across the broad infrared spectral band(2.5-25μm).While ultra-thin indium tin oxide(ITO)films have been demonstrated to exhibit superior infrared transmittance,their inherent low electrical conductivity necessitates additional enhancement strategies.This study systematically investigates the effects of oxygen vacancy concentration regulation and ultra-thin copper capping layer integration on the infrared optoelectronic properties of 20 nm-thick ITO films.A fundamental trade-off is revealed in ITO films that increased oxygen vacancy content enhances the electrical conductivity while compromising the infrared transmittance.Meanwhile,following the introduction of a Cu capping layer,the Cu/ITO system exhibits opposing dependencies of infrared transmittance and electrical conductivity on the capping layer thickness,with an optimum thickness of~3 nm.Finally,by constructing a Cu(3 nm)/ITO(20 nm)heterostructure with varying oxygen vacancy content,we demonstrate the combined effect of the ultra-thin Cu capping layer and moderate oxygen vacancy content on optimizing the carrier transport network.This configuration simultaneously minimizes surface/interfacial reflection and absorption losses,achieving high infrared transmittance(0.861)and a low sheet resistance of 400 W/sq.Our findings highlight the critical role of the combined effect of metal/oxide heterostructure design and defect engineering in optimizing infrared-transparent conductive properties.
基金National Key R&D Program of China(No.2022YFB3403500)the Science and Technology Program of Gansu Province(No.22JR5RA784).
文摘To address the future application requirements of carbon-based material grids for ion thrusters characterized by high thrust,elevated specific impulse,and extended operational life,research was conducted using the LIPS-100 ion thruster developed by the Lanzhou Institute of Physics.This study focused on small-diameter configurations of carbon-carbon composite material grids.Successful development was achieved for both a 10 cm split carbon-carbon planar grid and an integrated carbon-carbon convex grid component.Performance variations among different configurations were investigated through extensive performance tests across the wide-range from 1 to 25 mN,as well as 200 h lifespan assessments under typical conditions at 20 mN.The results indicate that the two configurations of the carbon-carbon grid can achieve stable operation across the broad range of 1-20 mN,with beam current fluctuations ranging from 368 to 379 mA and accel grid current fluctuations between 1.58 and 1.81 mA.Furthermore,the key performance parameters of these grids were comparable to those of the traditional molybdenum grids.Under conditions of high thrust and power,the carbon-carbon grid demonstrated a significant reduction in the intercepted current at the accel grid.In comparison to the split carbon-carbon planar grid,the weight of the integrated carbon-carbon convex composite grid was reduced by 17.5%,the anode voltage decreased by approximately 2.4%-8.6%,and the cathode keeper voltage was reduced by approximately 3.5%-12.4%.It can be concluded that the integrated carbon-carbon convex grid offers distinct advantages in terms of hot-state structural stability,suppression of grid etching rates,and enhancement of thruster discharge efficiency.
基金supported by the National Magnetic Confinement Fusion Science Program of China (Nos.2022YFE03100004,2017YFE0301700,2017YFE0301701 and 2022YFE03060003)National Natural Science Foundation of China (Nos.12375226,12175227,11875255 and 11975231)+2 种基金the China Postdoctoral Science Foundation (No.2022M723066)the Fundamental Research Funds for the Central Universitiesthe Collaborative Innovation Program of Hefei Science Center,CAS (No.2022HSCCIP022)。
文摘A 100-channel double-foil soft X-ray array imaging(DSXAI)diagnostic system has been developed for the HL-2A tokamak to obtain tomographic bremsstrahlung emissivity and electron temperature(T_(e)).This system employs a double-foil technique to determine T_(e) by comparing the soft X-ray(SXR)emissivities from the same plasma location through two beryllium(Be)foils of differing thickness.The DSXAI system comprises five photocameras mounted at two different poloidal cross-sections,separated toroidally by 15°,allowing for three distinct poloidal viewing angles.Each photocamera features 20 channels,offering a temporal resolution of approximately 4μs and a spatial resolution of about 8 cm,with no channel overlap.Each photocamera contains two identical optical systems,each defined by an aperture slit and a photodiode array.The double-foil configuration is realized by placing these two optical systems,each with a different Be foil,in close proximity.Initial experimental results demonstrate that the DSXAI diagnostic system performs well,successfully reconstructing 2-dimensional(2D)tomographic SXR emissivity and T_(e) on the HL-2A tokamak.This study provides valuable insights for the future implementation of similar diagnostic systems on fusion reactors like ITER.
文摘In this research work, atomic and molecular orbitals based analysis has been made to see electronic structure of platinum halides (platinum dichloride, platinum dibromide, platinum diiodide and platinum difluride). The geometry optimization and three dimensional (3D) modeling of the above mentioned species have been made on CAChe pro software. The results show: (i) The involvement of three p atomic orbitals is negligible as their summation values are very low in comparison to d orbital and considerably low with respect to s orbital. (ii) The study well support the Landis concepts of sdn-hybridation (here n = 1) as bond angle and contributions of s-orbital and d-orbital of Pt(II) are maximum with negligible contribution of p-orbitals. (iii) These halides also support the cloud-expanding effect with experimental data and also follow the nephelauxetic effect. The result is in good agreement with experiment results that covalent character increases in the order: PtI2 > PtBr2 > PtCl2 > PtF2. (iv) And thus the study will help to fine tune the existing complexes of these halides.
基金National Natural Science Foundation of China under Grant No.U2039209the National Key R&D Program of China under Grant No.2022YFC3004303+1 种基金the Heilongjiang Natural Science Foundation for Distinguished Young Scholars under Grant No.JQ2022E006Heilongjiang Natural Science Foundation Joint Guidance Project under Grant No.LH2021E122。
文摘The accurate simulation of wave propagation in real media requires properly taking the attenuation into account,which leads to wave dissipation together with its causal companion,wave dispersion.In this study,to obtain a weak formulation of heterogenous viscoacoustic wave propagation in an infinite domain,the viscoacoustic medium is first characterized by its frequency-dependent complex bulk compliance instead of the classically used complex bulk modulus.Then,a mechanical model using serially connected standard linear solids(SSLS)is built to obtain the rational approximation of the complex bulk compliance whose parameters are calculated via an adapted nonlinear optimization method.Utilizing the obtained bulk compliance-based constitutive relation,a novel second-order viscoacoustic wave equation in the frequency domain is derived,of which the weak formulation can be physically explained as the virtual work equation and can thus be discretized using a continuous spectral element method in space.Additionally,a new method is introduced to address the convolution terms involved in the inverse Fourier transform,whose accurate time integration can then be achieved using an explicit time scheme,which avoids the transient growth that exists in the classical method.The resulting full time-space decoupling scheme can handle wave propagation in arbitrary heterogeneous media.Moreover,to treat the wave propagation in an infinite domain,a perfectly matched layer in weak formulation is derived for the truncation of the infinite domain via complex coordinate stretching of the virtual work equation.With only minor modification,the resulting perfectly matched layer can be implemented using the same time scheme as for the wave equation inside the truncated domain.The accuracy,numerical stability,and versatility of the new proposed scheme are demonstrated with numerical examples.
基金supported by the Natu-ral Science Foundation of China and Fundamental Research Funds for the Central Universities(Grant Nos.42176006,42422601,202241006 to H.Y.)the Natural Science Foundation of China(Grant No.42225601 to Z.C.).
文摘Mesoscale air-sea interactions play a critical role in damping eddy activities.However,how mesoscale heat flux influences the distribution of eddy kinetic energy(EKE)in the wavenumber space remains unclear.In this study,we investigate the EKE and temperature variance(T_(var))budgets in the Kuroshio Extension(KE)region using wavenumber spectral analysis based on 1/10°coupled climate simulations.These simulations include a standard high-resolution simulation and a smoothed simulation that overlooks mesoscale heat flux.By comparing the differences between these models,we confirm that air-sea heat exchange significantly dissipates Tvar.Neglecting mesoscale heat flux results in a 60% underestimation of the Tvar damping rate,which in turn increases energy transfer to EKE through the vertical buoyancy flux by 22%.This enhanced vertical buoyancy flux leads to a 20% higher EKE level and larger energy budget terms,particularly in the diffusion term,which is closely related to wind power.Furthermore,underestimating air-sea heat exchange could lead to an overestimation of the inverse kinetic energy cascade,thereby distorting the overall energy budget in the KE region.
基金support from the Nuclear Fuel Pellet Appearance Quality Inspection Device Project(20190304 A).
文摘Thefield of energy storage devices is primarily dominated by lithium-ion batteries(LIBs)due to their mature manufacturing processes and stable performance.However,immature lithium recovery technology cannot stop the continuous increase in the cost of LIBs.Along with the rapid development of electric transportation,it has become inevitable to trigger a new round of competition in alternative energy storage systems.Some monovalent rechargeable metal ion batteries(sodium ion batteries(SIBs)and potassium ion batteries(PIBs),etc.)and multi-valent rechargeable metal-ion batteries(magnesium ion batteries(MIBs),calcium ion batteries(CIBs),zinc ion batteries(ZIBs),and aluminum ion batteries(AIBs),etc.)are potential candidates,which can replace LIBs in some of the scenarios to alleviate the pressure on supply.The cathode material plays a crucial role in determining the battery capacity.Transition metal compounds dominated by layered transition metal oxides as key cathode materials for secondary batteries play an important role in the advancement of various battery energy storage systems.In summary,this manuscript aims to review and summarize the research progress on transition metal compounds used as cathodes in different metal ion batteries,with the aim of providing valuable guidance for the exploration and design of high-performance integrated battery systems.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFE0105200)the China Postdoctoral Science Foundation(Grant No.2023M743151)the Natural Science Foundation of Henan Province,China(Grant No.242300420304)。
文摘Bi(Sb)_(2)Te(Se)_(3)alloys,as the only commercial thermoelectric materials,have been applied widely in cooling fields.While,the current energy conversion efficiency(dominated by the dimensionless ZT)of commercial products is still lower and cannot meet the market demand.In this paper,high thermoelectric performance at room temperature in both zonemelted(ZM)Bi_(0.46)Sb_(1.54)Te_(3)ingots and powder-metallurgy(PM)Bi_(0.46)Sb_(1.54)Te_(3)blocks with a large size was realized successfully by optimizing their preparation process.The peak ZT values of ZM and PM p-type Bi_(0.46)Sb_(1.54)Te_(3)alloys reached 1.26 and 1.45,respectively.They are higher than those of all the n-type or p-type Bi_(2)Te_(3)-based products in current commercial applications.In particular,their production process of large size p-type Bi_(0.46)Sb_(1.54)Te_(3)alloys could be directly industrialized.
文摘Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems is still a challenging problem that needs to be solved,as it affects reliability.Based on the analysis of in-orbit and ground test data of ion thrusters from simulation and experimental results,the main influencing factors of induced electric breakdown are clarified and the mechanisms of induced electric breakdown are analyzed.It is found that the main factors inducing breakdown are the voltage and electric field strength between the grids.In addition,by monitoring the waveform of plasma discharge,the temporal characteristics of breakdown can be defined as three stages of“breakdown-spark-loop response”.Thus,three kinds of engineering suppression methods for breakdown of static vacuum with periodic short-term heating,electrode surface polishing and sealing insulation with plasma,add energy suppression circuit are carried out,and the experimental results show that the electric breakdown frequency can be reduced by about 30%.
基金supported by the National Natural Science Foundation of China(No.41976217)the National Key R&D Program of China(No.2018YFA0605701).
文摘The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions across 14 summers from 1999 to 2022.In austral summer,the mCDW upwells along the upper continental slope then intrudes on the continental shelf across the shelf break in a warm tongue that gradually upwells poleward.The mCDW intrusion at the 73°E section is relatively weaker in December and stronger in February while showing significant interannual variability.During strong intrusions(January 2000 and February 2003),the mCDW extends southward to 68°S and upwells to 50 m,whereas the mCDW only reaches the shelf break during weak intrusions(December 2004,January 2006,January 2011,and February 2015).The intensity of the mCDW intrusions correlates strongly with the accumulated wind stress curl(30 days prior)north of the shelf break(73.5°-78.0°E,64.5°-66.0°S).The summertime westerly winds play a key role in regulating the interannual variability of mCDW intrusion onto the continental shelf.A southward shift of the westerly winds promotes the upwelling and southward intrusion of mCDW across the shelf break.In addition,mCDW at 73°E can reach as far as 68°S due to the southward flow of mCDW being hindered by a northward outflowing branch of the coastal current at the Amery Ice Shelf(AIS)front.In austral summer,the mCDW had never been observed at the section along the AIS front;thus,it cannot directly contribute to the basal melting of the ice shelf.
