Multi-angle statistical analysis of tropical cyclones(TCs)and their distant thermodynamic disturbances over Northwest Pacific from July to September during 2001-2020 was conducted.The results show that TCs could trigg...Multi-angle statistical analysis of tropical cyclones(TCs)and their distant thermodynamic disturbances over Northwest Pacific from July to September during 2001-2020 was conducted.The results show that TCs could trigger distant thermodynamic disturbances,which mainly caused an increase in air pressure and a rise in temperature in northern China.The distant thermodynamic disturbances triggered by TCs differed in spatial distribution and intensity in different months.In the same month,the spatial distribution of such disturbances triggered by high-intensity TCs was consistent with the overall pattern,and there was a significant increase in intensity and area.From the probability of TC activities and the significance test of variance of analysis under different levels of P-J index,it is found that TC activities could stimulate the increase of P-J teleconnection index.There was a significant positive correlation between them,which was accompanied by a step effect.展开更多
Sand/dust storms are some of the main hazards in arid and semi-arid zones. These storms also influence global environmental changes. By field observations, empirical statistics, and numerical simulations, pioneer rese...Sand/dust storms are some of the main hazards in arid and semi-arid zones. These storms also influence global environmental changes. By field observations, empirical statistics, and numerical simulations, pioneer researchers on these natural events have concluded the existence of a positive relationship between thermodynamic effects and sand/dust storms. Thermodynamic effects induce an unsteady stratified atmosphere to influence the process of these storms. However, studies on the relationship of thermodynamic effects with particles (i.e., sand and dust) are limited. In this article, wind tunnel with heating was used to simulate the quantitative relationship between thermodynamic effects and particle movement on different surfaces. Compared with the cold state, the threshold wind velocity of particles is found to be significantly decrease under the hot state. The largest decrease percentage exceedes 9% on fine and coarse sand surfaces. The wind velocity also has a three-power function in the sand transport rate under the hot state with increased sand transport. Thermodynamic effects are stronger on loose surfaces and fine particles, but weaker on compacted surfaces and coarse particles.展开更多
By employing a five-layer seasonal numerical weather prediction model and utilizing the National Meteorological Center (NMC) objective analysis data on May 10,1991 as the initial field,three numerical experiments——d...By employing a five-layer seasonal numerical weather prediction model and utilizing the National Meteorological Center (NMC) objective analysis data on May 10,1991 as the initial field,three numerical experiments——diabatic with orography,adiabatic with orography and adiabatic without orography——have been carried out to investigate the dy- namic and thermodynamic effects of the Qinghai-Xizang Plateau (hereafter the Plateau) on the seasonal transition in the early summer in East Asia.The results show that the typical seasonal transition features such as the northward shift of the subtropical westerly jet stream,the adjustment of the long-wave in middle and high latitudes and the changes of the circulation in the lower troposphere can be well simulated,if the dynamic and thermodynamic effects of the Plateau are both considered in the model as in the experiment adiabatic with orography.In other two experiments,it is failed to simulate out the seasonal transition features. The results also show that the thermodynamic effect of the Plateau acts on the atmosphere as a gradually enhanced heating source in the early summer,which makes the air temperature in 500 hPa over the Plateau increase by nearly 10℃ in a month and accelerates the northward shift of the subtropical westerly jet stream about seven latitudes more north- ward in twenty days and helps the shifted jet maintain at the northern periphery of the Plateau.It is also helpful to the formation and maintenance of the Lake Balchas trough and the northward and westward extension of the Pacific subtropical high.On the other hand,the dynamic effect of the Plateau weakens the northward shift of the subtropical westerly jet stream and barricades the westward extension of the Pacific subtropical high.If only the dynamic effect of the Plateau is considered in the model without consideration of the thermodynamic effect of the Plateau,not only the shifted jet withdraws southward but also the simulated Lake Balchas trough is 10 longitudes more eastward than that in the diabatic experiment,and the simulated Pacific subtropical high is more eastward and northward.However,the dy- namic effect of the Plateau strengthens the vertical movements in the west and east of the Plateau and makes the low-level jet maintain in the southeast of the Plateau.The path of the cold air and the tunnel of the water vapor in the lower troposphere during the seasonal transition period in the early summer in East Asia are determined by the coupling of the dynamic and thermodynamic effects of the Plateau.展开更多
An exceptional rainy season occurred in the Yangtze River valley of eastern China in June-July 2020.The relative importance of the dynamic and thermodynamic effects on this unusual event is evaluated through the budge...An exceptional rainy season occurred in the Yangtze River valley of eastern China in June-July 2020.The relative importance of the dynamic and thermodynamic effects on this unusual event is evaluated through the budget equations of moisture and moist static energy(MSE).The moisture budget analysis suggests that the thermodynamic effect contributes to the precipitation anomaly by 8.5%through the advection of abnormal water vapor by mean vertical motion,while the dynamic effect,related to water vapor advection by anomalous vertical motion,has the dominant contribution.The MSE budget analysis further reveals that the anomalous vertical motion is both constrained by the dynamic effect related to changes in atmospheric circulation and the thermodynamic effect related to changes of the atmospheric thermal state,with a ratio of thermodynamic versus total effects estimated at 45.3%.The dynamic effect is linked to the advection of warm and humid air by the abnormal southwesterly wind,which is related with an anomalous anticyclone over the Philippine Sea.The thermodynamic effect is partly induced by the positive advection of anomalous MSE(mainly latent energy)by the mean vertical motion.This analysis of the dynamic and thermodynamic effects is useful to understand the underlying physical mechanisms leading to the unusual rainy season in the Yangtze River valley in summer 2020.It is also helpful to put forward a few speculations on the potential role of global warming whose primary effect is,after all,to change the thermal state of the atmosphere.展开更多
For a black hole with two horizons, the effective entropy is assumed to be a linear combination of the two entropies of the outer and inner horizons. In terms of the effective thermodynamic quantities the effective Be...For a black hole with two horizons, the effective entropy is assumed to be a linear combination of the two entropies of the outer and inner horizons. In terms of the effective thermodynamic quantities the effective Bekenstein-Smarr formula and the effective first law of thermodynamics are derived.展开更多
Although fluorobis(phenylsulfonyl)methane(FBSM)and its cyclic analog 2-fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide(FBDT)possess similar physicochemical properties,Shibata et al.found that FBSM failed to undergo nucleo...Although fluorobis(phenylsulfonyl)methane(FBSM)and its cyclic analog 2-fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide(FBDT)possess similar physicochemical properties,Shibata et al.found that FBSM failed to undergo nucleophilic monofluoromethylation of aldehydes regardless of the reaction conditions at-tempted(using various organic and inorganic bases).However,it was later discovered by Hu et al.that the nucleophilic monofluoromethylation could be accomplished by employing lithium hexamethyldisi-lazide(LiHMDS)as a base.Herein,we present an in-depth computational investigation into the intrigu-ing effects of reagent structure and bases on the nucleophilic monofluoromethylation of aldehydes.The computations reveal the 1,4-diazabicyclo[2.2.2]octane(DABCO)catalyzed nucleophilic monofluoromethy-lation of benzaldehyde with acyclic FBSM is a thermodynamically unfavorable process mainly due to the destabilizing O···O lone pair repulsions in FBSM product,whereas such repulsion could be largely avoided in FBDT product because of its constrained five-membered ring structure.Employing LiHMDS as a base can not only facilitate the nucleophilic monofluoromethylation via Li–O interactions but also render the monofluoromethylation of benzaldehyde with FBSM thermodynamically favored.展开更多
A novel ferruginous active absorbent, prepared by fly ash, industrial lime and the additive Fe（VI）, was introduced for synchronous abatement of binary mixtures of SO2–NOx from simulated coal-fired flue gas. The syn...A novel ferruginous active absorbent, prepared by fly ash, industrial lime and the additive Fe（VI）, was introduced for synchronous abatement of binary mixtures of SO2–NOx from simulated coal-fired flue gas. The synergistic action of various factors on the absorption of SO2 and NOx was investigated. The results show that a strong synergistic effect exists between Fe（VI） dose and reaction temperature for the desulfurization. It was observed that in the denitration process, the synergy of Fe（VI） dose and Ca/（S ＋ N） had the most significant impact on the removal of NO, followed by the synergy of Fe（VI） and reaction temperature, and then the synergy of reaction temperature and flue gas humidity. A scanning electron microscope（SEM） and an accessory X-ray energy spectrometer（EDS）were used to observe the surface characteristics of the raw and spent absorbent as well as fly ash. A reaction mechanism was proposed based on chemical analysis of sulfur and nitrogen species concentrations in the spent absorbent. The Gibbs free energy, equilibrium constants and partial pressures of the SO2–NOx binary system were determined by thermodynamics.展开更多
We discuss black hole solutions of Einstein-Λ gravity in the presence of nonlinear electrodynamics in dS spacetime.Considering the correlation of the thermodynamic quantities respectively corresponding to the black h...We discuss black hole solutions of Einstein-Λ gravity in the presence of nonlinear electrodynamics in dS spacetime.Considering the correlation of the thermodynamic quantities respectively corresponding to the black hole horizon and cosmological horizon of dS spacetime and taking the region between the two horizons as a thermodynamic system,we derive effective thermodynamic quantities of the system according to the first law of thermodynamics,and investigate the thermodynamic properties of the system under the influence of nonlinearity parameter α.It is shown that nonlinearity parameter α influences the position of the black hole horizon and the critical state of the system,and along with electric charge has an effect on the phase structure of the system,which is obvious,especially as the effective temperature is below the critical temperature.The critical phase transition is proved to be second-order equilibrium phase transition by using the Gibbs free energy criterion and Ehrenfest equations.展开更多
An extremely heavy rainfall event lasting from 17 to 22 July 2021 occurred in Henan Province of China, with accumulated precipitation of more than 1000 mm over a 6-day period that exceeded its mean annual precipitatio...An extremely heavy rainfall event lasting from 17 to 22 July 2021 occurred in Henan Province of China, with accumulated precipitation of more than 1000 mm over a 6-day period that exceeded its mean annual precipitation. The present study examines the roles of persistent low-level jets(LLJs) in maintaining the precipitation using surface station observations and reanalysis datasets. The LLJs triggered strong ascending motions and carried moisture mainly from the outflow of Typhoon In-fa(2021). The varying directions of the LLJs well corresponded to the meridional shifts of the rainfall. The precipitation rate reached a maximum during 20-21 July as the LLJs strengthened and expanded vertically into double LLJs, including synoptic-weather-system-related LLJs(SLLJs) at 850–700 hPa and boundary-layer jets(BLJs)at ~950 hPa. The coupling of the SLLJ and BLJ provided strong mid-and low-level convergence on 20 July, whereas the SLLJ produced mid-level divergence at its entrance that coupled with low-level convergence at the terminus of the BLJ on21 July. The formation mechanisms of the two types of LLJs are further examined. The SLLJs and the low-pressure vortex(or inverted trough) varied synchronously as a whole and were affected by the southwestward movement of the WPSH in the rainiest period. The persistent large total pressure gradient force at low levels also maintained the strength of low-level geostrophic winds, thus sustaining the BLJs on the synoptic scale. The results based on a Du-Rotunno 1D model show that the Blackadar and Holton mechanisms jointly governed the BLJ dynamics on the diurnal scale.展开更多
The objective of this study is to analyze the fundamental characteristics and the thermodynamic effects of cavitating flows in liquid hydrogen.For this purpose,numerical simulation of cavitating flows are conducted ov...The objective of this study is to analyze the fundamental characteristics and the thermodynamic effects of cavitating flows in liquid hydrogen.For this purpose,numerical simulation of cavitating flows are conducted over a three dimensional hydrofoil in liquid hydrogen.Firstly,the efficiency of this computational methodology is validated through comparing the simulation results with the experimental measurements of pressure and temperature.Secondly,after analysing the cavitating flows in liquid hydrogen and water,the characteristics under cryogenic conditions are highlighted.The results show that the thermodynamic effects play a significant role in the cavity structure and the mass transfer,the dimensionless mass transfer rate of liquid hydrogen is much larger,and the peak value is about ninety times as high as water at room temperature.Furthermore,a parametric study of cavitating flows on hydrofoil is conducted by considering different cavitation number and dimensionless thermodynamic coefficient.The obtained results provide an insight into the thermodynamic effect on the cavitating flows.展开更多
An effective thermodynamic transformation analysis method was proposed in this study. According to the phenomenon of ex- ergy consumption always coupling with heat transfer process, the effective thermodynamic tempera...An effective thermodynamic transformation analysis method was proposed in this study. According to the phenomenon of ex- ergy consumption always coupling with heat transfer process, the effective thermodynamic temperatures were defined, then the actual power cycle or refrigeration/heat pump cycle was transformed into the equivalent reversible Carnot or reverse Carnot cycles for thermodynamic analysis. The derived effective thermodynamic temperature of the hot reservoir of the equivalent reverse Camot cycle is the basis of the proposed method. The combined diagram of TR-h and TR-q was adopted for the analy- sis of the system performance and the exergy consumption, which takes advantage of the visual expression of the heat/work exchange and the enthalpy change, and is convenient for the calculation of the coefficient of performance and exergy con- sumptions. Take a heat pump water heater with refrigerant of R22 for example, the proposed method was systematically intro- duced, and the fitting formulas of the effective thermodynamic temperatures were given as demonstration. The results show that the proposed method has advantage and well application foreground in the performance simulation and estimation under the variable working conditions.展开更多
Based on modern observations,historical proxy data,and climate model simulations,this paper provides a comprehensive overview of the past,present and future evolution characteristics of the Atlantic Meridional Overtur...Based on modern observations,historical proxy data,and climate model simulations,this paper provides a comprehensive overview of the past,present and future evolution characteristics of the Atlantic Meridional Overturning Circulation(AMOC),as well as its impact on the surface air temperature(SAT)at regional and hemispherical scales.The reconstruction results based on the proxy data indicate that the AMOC has weakened since the late 19th century and experienced overall weakening throughout the 20th century with low confidence.Direct observations show that the AMOC weakened during 2004–2016,but it is not possible to distinguish between its decadal variability and long-term trend.Climate models predict that if greenhouse gas emissions continue to increase,AMOC will weaken in the future,but there will not be a sudden collapse before 2100.For the thermodynamic effects of AMOC,the increased surface heat flux release and meridional heat transport(MHT)over the North Atlantic associated with the strong AMOC cause an increase in the hemispherical SAT.At the millennial scale,climate cooling(warming)periods correspond to a weakened(strengthened)AMOC.The enhanced MHT of a strong AMOC can affect Arctic warming and thus influence regional SAT anomalies and SAT extremes through mutual feedback between Arctic sea ice and AMOC.In terms of dynamic effects,a strong AMOC modulates the Rossby wave trains originating from the North Atlantic and spreading across mid-to-high latitudes in the Northern Hemisphere and causes an increase in the variabilities in the circulation anomalies over the Ural and Siberian regions.Ultimately,a strong AMOC significantly affects the frequencies of extreme cold and warm events in the mid-to-high latitude regions over Eurasia.In addition,AMOC can also influence regional and global SAT anomalies through its dynamic adjustment of planetary-scale circulation.Decadal variation in AMOC is closely related to the Atlantic Multidecadal Oscillation(AMO).During positive phases of AMO and AMOC,enhanced surface heat fluxes over the North Atlantic lead to abnormal warming in the Northern Hemisphere,while during negative phases,the reverse case occurs.Under high emission scenarios in the future,the possibility of AMOC collapse increases due to freshwater forcing.However,most advanced climate models underestimate the strength of the AMOC and its impact on the AMO and relevant climate change,which presents a major challenge for future understanding and prediction of the AMOC and its climate effects.展开更多
By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather pro...By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather processes of the rain during the onset period of the summer monsoon in Eastern Asia in 1979 were studied numerically.According to the initial field of 12GMT 14 June 1979,five-day numerical experiments with or without the orographic effects were carried out respectively.The results show that the Plateau can influence the precipitation significantly during the summer monsoon season.Although the summer monsoon is the result of the seasonal variations of the global circulation and the heating difference between land and sea,it is influenced evidently by the Plateau in medium-range processes.There are very complex interactions between the mountain and diabatic heating effects so that both of them should be considered correctly in the general circulation models in order to describe the nature of the atmosphere reliably.展开更多
In the extended thermodynamics of black holes,there exists a thermodynamical pressure whose dual thermodynamical quantity is volume.Extensive studies have been conducted on the phase structure of numerous black holes,...In the extended thermodynamics of black holes,there exists a thermodynamical pressure whose dual thermodynamical quantity is volume.Extensive studies have been conducted on the phase structure of numerous black holes,demonstrating striking similarities to the phase structures of various ordinary matter systems.From a comparison between the thermodynamic properties of spherically symmetric AdS black holes and ordinary thermodynamic systems,we know that the isovolumetric heat capacity of the former is zero,whereas that of the latter is non-zero.The intrinsic reason for this discrepancy is a topic of interest.For Reissner-Nördstrom-de Sitter(RN-dS)spacetime with the coexistence of the black hole and cosmological horizons,the effective thermodynamic quantities are presented alongside the interaction between two horizons.The heat capacity in RN-dS spacetime is then investigated,and it is demonstrated that the behavior of the heat capacity in RN-dS spacetime is analogous to that of Schottky specific heat.Treating two horizons in RN-dS spacetime as two distinct energy levels in a two-energy-level system,we investigate the thermodynamic properties in RN-dS spacetime by studying the thermodynamic properties in an ordinary two-energy system,thereby elucidating the intrinsic reasons for the occurrence of Schottky specific heat in RN-dS spacetime.The heat capacity observed in RN-dS spacetime is not only consistent with that of Schottky specific heat described by the effective thermodynamic quantities in RN-dS spacetime but also with that of an ordinary two-energy-level system.These results not only reveal the quantum properties of RN-dS spacetime but also provide a new avenue for further in-depth study of the quantum properties of black holes and dS spacetime.展开更多
How to solve the hypersonic aerothermodynamics around large-scale uncontrolled spacecraft during falling disintegrated process from outer space to earth,is the key to resolve the problems of the uncontrolled Tiangong-...How to solve the hypersonic aerothermodynamics around large-scale uncontrolled spacecraft during falling disintegrated process from outer space to earth,is the key to resolve the problems of the uncontrolled Tiangong-No.1 spacecraft reentry crash.To study aerodynamics of spacecraft reentry covering various flow regimes,a Gas-Kinetic Unified Algorithm(GKUA)has been presented by computable modeling of the collision integral of the Boltzmann equation over tens of years.On this basis,the rotational and vibrational energy modes are considered as the independent variables of the gas molecular velocity distribution function,a kind of Boltzmann model equation involving in internal energy excitation is presented by decomposing the collision term of the Boltzmann equation into elastic and inelastic collision terms.Then,the gas-kinetic numerical scheme is constructed to capture the time evolution of the discretized velocity distribution functions by developing the discrete velocity ordinate method and numerical quadrature technique.The unified algorithm of the Boltzmann model equation involving thermodynamics non-equilibrium effect is presented for the whole range of flow regimes.The gas-kinetic massive parallel computing strategy is developed to solve the hypersonic aerothermodynamics with the processor cores 500~45,000 at least 80%parallel efficiency.To validate the accuracy of the GKUA,the hypersonic flows are simulated including the reentry Tiangong-1 spacecraft shape with the wide range of Knudsen numbers of 220~0.00005 by the comparison of the related results from the DSMC and N-S coupled methods,and the low-density tunnel experiment etc.For uncontrolling spacecraft falling problem,the finite-element algorithm for dynamic thermalforce coupling response is presented,and the unified simulation of the thermal structural response and the hypersonic flow field is tested on the Tiangong-1 shape under reentry aerodynamic environment.Then,the forecasting analysis platform of end-of-life largescale spacecraft flying track is established on the basis of ballistic computation combined with reentry aerothermodynamics and deformation failure/disintegration.展开更多
Kelvin–Helmholtz(KH)instability is a fundamental fluid instability that widely exists in nature and engineering.To better understand the dynamic process of the KH instability,the influence of the tangential velocity ...Kelvin–Helmholtz(KH)instability is a fundamental fluid instability that widely exists in nature and engineering.To better understand the dynamic process of the KH instability,the influence of the tangential velocity on the compressible KH instability is investigated by using the discrete Boltzmann method based on the nonequilibrium statistical physics.Both hydrodynamic and thermodynamic nonequilibrium(TNE)effects are probed and analyzed.It is found that,on the whole,the global density gradients,the TNE strength and area firstly increase and decrease afterwards.Both the global density gradient and heat flux intensity in the vertical direction are almost constant in the initial stage before a vortex forms.Moreover,with the increase of the tangential velocity,the KH instability evolves faster,hence the global density gradients,the TNE strength and area increase in the initial stage and achieve their peak earlier,and their maxima are higher for a larger tangential velocity.Physically,there are several competitive mechanisms in the evolution of the KH instability.(i)The physical gradients increase and the TNE effects are strengthened as the interface is elongated.The local physical gradients decrease and the local TNE intensity is weakened on account of the dissipation and/or diffusion.(ii)The global heat flux intensity is promoted when the physical gradients increase.As the contact area expands,the heat exchange is enhanced and the global heat flux intensity increases.(iii)The global TNE intensity reduces with the decreasing of physical gradients and increase with the increasing of TNE area.(iv)The nonequilibrium area increases as the fluid interface is elongated and is widened because of the dissipation and/or diffusion.展开更多
Developing a robust computational strategy to address the rich physical characteristic involved in the thermcdynamic effects on the cryogenic cavitation remains a challenge in research. The objective of the present st...Developing a robust computational strategy to address the rich physical characteristic involved in the thermcdynamic effects on the cryogenic cavitation remains a challenge in research. The objective of the present study is to focus on developing mod- elling strategy to simulate cavitating flows in liquid nitrogen. For this purpose, numerical simulation over a 2D quarter caliber hydrofoil is investigated by calibrating cavitation model parameters and implementing the thermodynamic effects to the Zwart cavitation model. Experimental measurements of pressure and temperature are utilized to validate the extensional Zwart cavi- tation model. The results show that the cavitation dynamics characteristic under the cryogenic environment ale different from that under the isothermal conditions： the cryogenic case yields a substantially shorter cavity around the hydrofoil, and the pre- dicted pressure and temperature inside the cavity are steeper under the cryogenic conditions. Compared with the experimental data, the computational predictions with the modified evaporation and condensation parameters display better results than the default parameters from the room temperature liquids. Based on a wide range of computations and comparisons, the extension- al Zwart cavitation model may predict more accurately the quasi-steady cavitation over a hydrofoil in liquid nitrogen by pri- marily altering the evaporation rate near the leading edge and the condensation rate in the cavity closure region.展开更多
Recently,some meaningful results have been obtained by studying the phase transition,critical exponents,and other thermodynamical properties of different black holes.Especially for the Anti-de Sitter(AdS)black holes,t...Recently,some meaningful results have been obtained by studying the phase transition,critical exponents,and other thermodynamical properties of different black holes.Especially for the Anti-de Sitter(AdS)black holes,their thermodynamical properties nearby the critical point have attracted considerable attention.However,there exists little work on the thermodynamic properties of the de Sitter(dS)spacetime with black holes.In this paper,based on the effective thermodynamical quantities and the method of the Maxwell's equal-area law,we explore the phase equilibrium for the de Sitter spacetime with the charged black holes and the cloud of string and quintessence(i.e.,C-dSSQ spacetime).The boundaries of the two-phase coexistence region in both P_(eff)−T_(eff)and T_(eff)−S diagrams are obtained.The coexistent curve and the latent heat of phase transition for this system are also investigated.Furthermore,we analyze the effect of parameters(the state parameterωand the ratio of two horizon radii x=r+/r_(c))on the two-phase coexistence region boundary.The results indicate that the phase transition in C-dSSQ spacetime is analogous to that in a van der Waals fluid(vdw)system,which is determined by the electrical potential at the horizon.These results are helpful for understanding the basic properties of black holes and are also of great value for the establishment of quantum gravity.展开更多
基金the National Natural Science Foundation of China(42305011).
文摘Multi-angle statistical analysis of tropical cyclones(TCs)and their distant thermodynamic disturbances over Northwest Pacific from July to September during 2001-2020 was conducted.The results show that TCs could trigger distant thermodynamic disturbances,which mainly caused an increase in air pressure and a rise in temperature in northern China.The distant thermodynamic disturbances triggered by TCs differed in spatial distribution and intensity in different months.In the same month,the spatial distribution of such disturbances triggered by high-intensity TCs was consistent with the overall pattern,and there was a significant increase in intensity and area.From the probability of TC activities and the significance test of variance of analysis under different levels of P-J index,it is found that TC activities could stimulate the increase of P-J teleconnection index.There was a significant positive correlation between them,which was accompanied by a step effect.
基金Under the auspices of National Natural Science Foundation of China(No.40930741,41071009,41001005)Knowledge Innovation Programs of Chinese Academy of Sciences(No.KZCX2-YW-329)
文摘Sand/dust storms are some of the main hazards in arid and semi-arid zones. These storms also influence global environmental changes. By field observations, empirical statistics, and numerical simulations, pioneer researchers on these natural events have concluded the existence of a positive relationship between thermodynamic effects and sand/dust storms. Thermodynamic effects induce an unsteady stratified atmosphere to influence the process of these storms. However, studies on the relationship of thermodynamic effects with particles (i.e., sand and dust) are limited. In this article, wind tunnel with heating was used to simulate the quantitative relationship between thermodynamic effects and particle movement on different surfaces. Compared with the cold state, the threshold wind velocity of particles is found to be significantly decrease under the hot state. The largest decrease percentage exceedes 9% on fine and coarse sand surfaces. The wind velocity also has a three-power function in the sand transport rate under the hot state with increased sand transport. Thermodynamic effects are stronger on loose surfaces and fine particles, but weaker on compacted surfaces and coarse particles.
文摘By employing a five-layer seasonal numerical weather prediction model and utilizing the National Meteorological Center (NMC) objective analysis data on May 10,1991 as the initial field,three numerical experiments——diabatic with orography,adiabatic with orography and adiabatic without orography——have been carried out to investigate the dy- namic and thermodynamic effects of the Qinghai-Xizang Plateau (hereafter the Plateau) on the seasonal transition in the early summer in East Asia.The results show that the typical seasonal transition features such as the northward shift of the subtropical westerly jet stream,the adjustment of the long-wave in middle and high latitudes and the changes of the circulation in the lower troposphere can be well simulated,if the dynamic and thermodynamic effects of the Plateau are both considered in the model as in the experiment adiabatic with orography.In other two experiments,it is failed to simulate out the seasonal transition features. The results also show that the thermodynamic effect of the Plateau acts on the atmosphere as a gradually enhanced heating source in the early summer,which makes the air temperature in 500 hPa over the Plateau increase by nearly 10℃ in a month and accelerates the northward shift of the subtropical westerly jet stream about seven latitudes more north- ward in twenty days and helps the shifted jet maintain at the northern periphery of the Plateau.It is also helpful to the formation and maintenance of the Lake Balchas trough and the northward and westward extension of the Pacific subtropical high.On the other hand,the dynamic effect of the Plateau weakens the northward shift of the subtropical westerly jet stream and barricades the westward extension of the Pacific subtropical high.If only the dynamic effect of the Plateau is considered in the model without consideration of the thermodynamic effect of the Plateau,not only the shifted jet withdraws southward but also the simulated Lake Balchas trough is 10 longitudes more eastward than that in the diabatic experiment,and the simulated Pacific subtropical high is more eastward and northward.However,the dy- namic effect of the Plateau strengthens the vertical movements in the west and east of the Plateau and makes the low-level jet maintain in the southeast of the Plateau.The path of the cold air and the tunnel of the water vapor in the lower troposphere during the seasonal transition period in the early summer in East Asia are determined by the coupling of the dynamic and thermodynamic effects of the Plateau.
基金Supported by the National Key Research and Development Program of China(2018YFC1507704)National Natural Science Foundation of China(42088101)。
文摘An exceptional rainy season occurred in the Yangtze River valley of eastern China in June-July 2020.The relative importance of the dynamic and thermodynamic effects on this unusual event is evaluated through the budget equations of moisture and moist static energy(MSE).The moisture budget analysis suggests that the thermodynamic effect contributes to the precipitation anomaly by 8.5%through the advection of abnormal water vapor by mean vertical motion,while the dynamic effect,related to water vapor advection by anomalous vertical motion,has the dominant contribution.The MSE budget analysis further reveals that the anomalous vertical motion is both constrained by the dynamic effect related to changes in atmospheric circulation and the thermodynamic effect related to changes of the atmospheric thermal state,with a ratio of thermodynamic versus total effects estimated at 45.3%.The dynamic effect is linked to the advection of warm and humid air by the abnormal southwesterly wind,which is related with an anomalous anticyclone over the Philippine Sea.The thermodynamic effect is partly induced by the positive advection of anomalous MSE(mainly latent energy)by the mean vertical motion.This analysis of the dynamic and thermodynamic effects is useful to understand the underlying physical mechanisms leading to the unusual rainy season in the Yangtze River valley in summer 2020.It is also helpful to put forward a few speculations on the potential role of global warming whose primary effect is,after all,to change the thermal state of the atmosphere.
文摘For a black hole with two horizons, the effective entropy is assumed to be a linear combination of the two entropies of the outer and inner horizons. In terms of the effective thermodynamic quantities the effective Bekenstein-Smarr formula and the effective first law of thermodynamics are derived.
基金supported by the Natural Science Foundation of China(Nos.22122104,21933004 and 21702098).
文摘Although fluorobis(phenylsulfonyl)methane(FBSM)and its cyclic analog 2-fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide(FBDT)possess similar physicochemical properties,Shibata et al.found that FBSM failed to undergo nucleophilic monofluoromethylation of aldehydes regardless of the reaction conditions at-tempted(using various organic and inorganic bases).However,it was later discovered by Hu et al.that the nucleophilic monofluoromethylation could be accomplished by employing lithium hexamethyldisi-lazide(LiHMDS)as a base.Herein,we present an in-depth computational investigation into the intrigu-ing effects of reagent structure and bases on the nucleophilic monofluoromethylation of aldehydes.The computations reveal the 1,4-diazabicyclo[2.2.2]octane(DABCO)catalyzed nucleophilic monofluoromethy-lation of benzaldehyde with acyclic FBSM is a thermodynamically unfavorable process mainly due to the destabilizing O···O lone pair repulsions in FBSM product,whereas such repulsion could be largely avoided in FBDT product because of its constrained five-membered ring structure.Employing LiHMDS as a base can not only facilitate the nucleophilic monofluoromethylation via Li–O interactions but also render the monofluoromethylation of benzaldehyde with FBSM thermodynamically favored.
基金supported by the National Natural Science Foundation of China (Nos. 51308212, 10974053)the National Key Technology R&D Program (No. 2011BAI02B03)+1 种基金the Fundamental Research Funds for the Central Universities (No. 13ZD18)the State Scholarship Fund (No. 201206735009)
文摘A novel ferruginous active absorbent, prepared by fly ash, industrial lime and the additive Fe（VI）, was introduced for synchronous abatement of binary mixtures of SO2–NOx from simulated coal-fired flue gas. The synergistic action of various factors on the absorption of SO2 and NOx was investigated. The results show that a strong synergistic effect exists between Fe（VI） dose and reaction temperature for the desulfurization. It was observed that in the denitration process, the synergy of Fe（VI） dose and Ca/（S ＋ N） had the most significant impact on the removal of NO, followed by the synergy of Fe（VI） and reaction temperature, and then the synergy of reaction temperature and flue gas humidity. A scanning electron microscope（SEM） and an accessory X-ray energy spectrometer（EDS）were used to observe the surface characteristics of the raw and spent absorbent as well as fly ash. A reaction mechanism was proposed based on chemical analysis of sulfur and nitrogen species concentrations in the spent absorbent. The Gibbs free energy, equilibrium constants and partial pressures of the SO2–NOx binary system were determined by thermodynamics.
基金supported by NSFC under Grant No.11705107by the doctoral Sustentation Fund of Shanxi Datong University(2015-B-10).
文摘We discuss black hole solutions of Einstein-Λ gravity in the presence of nonlinear electrodynamics in dS spacetime.Considering the correlation of the thermodynamic quantities respectively corresponding to the black hole horizon and cosmological horizon of dS spacetime and taking the region between the two horizons as a thermodynamic system,we derive effective thermodynamic quantities of the system according to the first law of thermodynamics,and investigate the thermodynamic properties of the system under the influence of nonlinearity parameter α.It is shown that nonlinearity parameter α influences the position of the black hole horizon and the critical state of the system,and along with electric charge has an effect on the phase structure of the system,which is obvious,especially as the effective temperature is below the critical temperature.The critical phase transition is proved to be second-order equilibrium phase transition by using the Gibbs free energy criterion and Ehrenfest equations.
基金supported by Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)the National Natural Science Foundation of China(Grant Nos.42122033,41875055,and 42075006)Guangzhou Science and Technology Plan Projects(202002030346 and 202002030196).
文摘An extremely heavy rainfall event lasting from 17 to 22 July 2021 occurred in Henan Province of China, with accumulated precipitation of more than 1000 mm over a 6-day period that exceeded its mean annual precipitation. The present study examines the roles of persistent low-level jets(LLJs) in maintaining the precipitation using surface station observations and reanalysis datasets. The LLJs triggered strong ascending motions and carried moisture mainly from the outflow of Typhoon In-fa(2021). The varying directions of the LLJs well corresponded to the meridional shifts of the rainfall. The precipitation rate reached a maximum during 20-21 July as the LLJs strengthened and expanded vertically into double LLJs, including synoptic-weather-system-related LLJs(SLLJs) at 850–700 hPa and boundary-layer jets(BLJs)at ~950 hPa. The coupling of the SLLJ and BLJ provided strong mid-and low-level convergence on 20 July, whereas the SLLJ produced mid-level divergence at its entrance that coupled with low-level convergence at the terminus of the BLJ on21 July. The formation mechanisms of the two types of LLJs are further examined. The SLLJs and the low-pressure vortex(or inverted trough) varied synchronously as a whole and were affected by the southwestward movement of the WPSH in the rainiest period. The persistent large total pressure gradient force at low levels also maintained the strength of low-level geostrophic winds, thus sustaining the BLJs on the synoptic scale. The results based on a Du-Rotunno 1D model show that the Blackadar and Holton mechanisms jointly governed the BLJ dynamics on the diurnal scale.
基金Sponsored by the Natural Science Foundation of Heilongjiang Province of China(Grant No.A201409)the Special Fund Project for Technology Innovation Talent of Harbin(Grant No.2013RFLXJ007)the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.201159)
文摘The objective of this study is to analyze the fundamental characteristics and the thermodynamic effects of cavitating flows in liquid hydrogen.For this purpose,numerical simulation of cavitating flows are conducted over a three dimensional hydrofoil in liquid hydrogen.Firstly,the efficiency of this computational methodology is validated through comparing the simulation results with the experimental measurements of pressure and temperature.Secondly,after analysing the cavitating flows in liquid hydrogen and water,the characteristics under cryogenic conditions are highlighted.The results show that the thermodynamic effects play a significant role in the cavity structure and the mass transfer,the dimensionless mass transfer rate of liquid hydrogen is much larger,and the peak value is about ninety times as high as water at room temperature.Furthermore,a parametric study of cavitating flows on hydrofoil is conducted by considering different cavitation number and dimensionless thermodynamic coefficient.The obtained results provide an insight into the thermodynamic effect on the cavitating flows.
基金supported by the National Natural Science Foundation of China (Grant No. 51076147)
文摘An effective thermodynamic transformation analysis method was proposed in this study. According to the phenomenon of ex- ergy consumption always coupling with heat transfer process, the effective thermodynamic temperatures were defined, then the actual power cycle or refrigeration/heat pump cycle was transformed into the equivalent reversible Carnot or reverse Carnot cycles for thermodynamic analysis. The derived effective thermodynamic temperature of the hot reservoir of the equivalent reverse Camot cycle is the basis of the proposed method. The combined diagram of TR-h and TR-q was adopted for the analy- sis of the system performance and the exergy consumption, which takes advantage of the visual expression of the heat/work exchange and the enthalpy change, and is convenient for the calculation of the coefficient of performance and exergy con- sumptions. Take a heat pump water heater with refrigerant of R22 for example, the proposed method was systematically intro- duced, and the fitting formulas of the effective thermodynamic temperatures were given as demonstration. The results show that the proposed method has advantage and well application foreground in the performance simulation and estimation under the variable working conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.41822503 and 42175053)the National Key Research and Development Program(Grant No.2016YFA0601502).
文摘Based on modern observations,historical proxy data,and climate model simulations,this paper provides a comprehensive overview of the past,present and future evolution characteristics of the Atlantic Meridional Overturning Circulation(AMOC),as well as its impact on the surface air temperature(SAT)at regional and hemispherical scales.The reconstruction results based on the proxy data indicate that the AMOC has weakened since the late 19th century and experienced overall weakening throughout the 20th century with low confidence.Direct observations show that the AMOC weakened during 2004–2016,but it is not possible to distinguish between its decadal variability and long-term trend.Climate models predict that if greenhouse gas emissions continue to increase,AMOC will weaken in the future,but there will not be a sudden collapse before 2100.For the thermodynamic effects of AMOC,the increased surface heat flux release and meridional heat transport(MHT)over the North Atlantic associated with the strong AMOC cause an increase in the hemispherical SAT.At the millennial scale,climate cooling(warming)periods correspond to a weakened(strengthened)AMOC.The enhanced MHT of a strong AMOC can affect Arctic warming and thus influence regional SAT anomalies and SAT extremes through mutual feedback between Arctic sea ice and AMOC.In terms of dynamic effects,a strong AMOC modulates the Rossby wave trains originating from the North Atlantic and spreading across mid-to-high latitudes in the Northern Hemisphere and causes an increase in the variabilities in the circulation anomalies over the Ural and Siberian regions.Ultimately,a strong AMOC significantly affects the frequencies of extreme cold and warm events in the mid-to-high latitude regions over Eurasia.In addition,AMOC can also influence regional and global SAT anomalies through its dynamic adjustment of planetary-scale circulation.Decadal variation in AMOC is closely related to the Atlantic Multidecadal Oscillation(AMO).During positive phases of AMO and AMOC,enhanced surface heat fluxes over the North Atlantic lead to abnormal warming in the Northern Hemisphere,while during negative phases,the reverse case occurs.Under high emission scenarios in the future,the possibility of AMOC collapse increases due to freshwater forcing.However,most advanced climate models underestimate the strength of the AMOC and its impact on the AMO and relevant climate change,which presents a major challenge for future understanding and prediction of the AMOC and its climate effects.
文摘By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather processes of the rain during the onset period of the summer monsoon in Eastern Asia in 1979 were studied numerically.According to the initial field of 12GMT 14 June 1979,five-day numerical experiments with or without the orographic effects were carried out respectively.The results show that the Plateau can influence the precipitation significantly during the summer monsoon season.Although the summer monsoon is the result of the seasonal variations of the global circulation and the heating difference between land and sea,it is influenced evidently by the Plateau in medium-range processes.There are very complex interactions between the mountain and diabatic heating effects so that both of them should be considered correctly in the general circulation models in order to describe the nature of the atmosphere reliably.
基金Supported by the Natural Science Foundation of China(12375050,11705106,12075143)the Scientific Innovation Foundation of the Higher Education Institutions of Shanxi Province,China(2023L269)+2 种基金the Science Foundation of Shanxi Datong University(2022Q1,2020Q2)the Natural Science Foundation of Shanxi Province,China(202203021221209,202303021211180)the Teaching Reform Project of Shanxi Datong University(XJG2022234)。
文摘In the extended thermodynamics of black holes,there exists a thermodynamical pressure whose dual thermodynamical quantity is volume.Extensive studies have been conducted on the phase structure of numerous black holes,demonstrating striking similarities to the phase structures of various ordinary matter systems.From a comparison between the thermodynamic properties of spherically symmetric AdS black holes and ordinary thermodynamic systems,we know that the isovolumetric heat capacity of the former is zero,whereas that of the latter is non-zero.The intrinsic reason for this discrepancy is a topic of interest.For Reissner-Nördstrom-de Sitter(RN-dS)spacetime with the coexistence of the black hole and cosmological horizons,the effective thermodynamic quantities are presented alongside the interaction between two horizons.The heat capacity in RN-dS spacetime is then investigated,and it is demonstrated that the behavior of the heat capacity in RN-dS spacetime is analogous to that of Schottky specific heat.Treating two horizons in RN-dS spacetime as two distinct energy levels in a two-energy-level system,we investigate the thermodynamic properties in RN-dS spacetime by studying the thermodynamic properties in an ordinary two-energy system,thereby elucidating the intrinsic reasons for the occurrence of Schottky specific heat in RN-dS spacetime.The heat capacity observed in RN-dS spacetime is not only consistent with that of Schottky specific heat described by the effective thermodynamic quantities in RN-dS spacetime but also with that of an ordinary two-energy-level system.These results not only reveal the quantum properties of RN-dS spacetime but also provide a new avenue for further in-depth study of the quantum properties of black holes and dS spacetime.
基金The National Key Basic Research and Development Program(2014CB744100)and the National Natural Science Foundation of China(91530319 and 11325212)support the present researches in the design of the study and collection,analysis,and interpretation of data and in writing the manuscript.
文摘How to solve the hypersonic aerothermodynamics around large-scale uncontrolled spacecraft during falling disintegrated process from outer space to earth,is the key to resolve the problems of the uncontrolled Tiangong-No.1 spacecraft reentry crash.To study aerodynamics of spacecraft reentry covering various flow regimes,a Gas-Kinetic Unified Algorithm(GKUA)has been presented by computable modeling of the collision integral of the Boltzmann equation over tens of years.On this basis,the rotational and vibrational energy modes are considered as the independent variables of the gas molecular velocity distribution function,a kind of Boltzmann model equation involving in internal energy excitation is presented by decomposing the collision term of the Boltzmann equation into elastic and inelastic collision terms.Then,the gas-kinetic numerical scheme is constructed to capture the time evolution of the discretized velocity distribution functions by developing the discrete velocity ordinate method and numerical quadrature technique.The unified algorithm of the Boltzmann model equation involving thermodynamics non-equilibrium effect is presented for the whole range of flow regimes.The gas-kinetic massive parallel computing strategy is developed to solve the hypersonic aerothermodynamics with the processor cores 500~45,000 at least 80%parallel efficiency.To validate the accuracy of the GKUA,the hypersonic flows are simulated including the reentry Tiangong-1 spacecraft shape with the wide range of Knudsen numbers of 220~0.00005 by the comparison of the related results from the DSMC and N-S coupled methods,and the low-density tunnel experiment etc.For uncontrolling spacecraft falling problem,the finite-element algorithm for dynamic thermalforce coupling response is presented,and the unified simulation of the thermal structural response and the hypersonic flow field is tested on the Tiangong-1 shape under reentry aerodynamic environment.Then,the forecasting analysis platform of end-of-life largescale spacecraft flying track is established on the basis of ballistic computation combined with reentry aerothermodynamics and deformation failure/disintegration.
基金supported by the National Natural Science Foundation of China(Grant Nos.51806116 and 11875001)the Natural Science Foundation of Fujian Provinces(Grant Nos.2021J01652 and 2021J01655).
文摘Kelvin–Helmholtz(KH)instability is a fundamental fluid instability that widely exists in nature and engineering.To better understand the dynamic process of the KH instability,the influence of the tangential velocity on the compressible KH instability is investigated by using the discrete Boltzmann method based on the nonequilibrium statistical physics.Both hydrodynamic and thermodynamic nonequilibrium(TNE)effects are probed and analyzed.It is found that,on the whole,the global density gradients,the TNE strength and area firstly increase and decrease afterwards.Both the global density gradient and heat flux intensity in the vertical direction are almost constant in the initial stage before a vortex forms.Moreover,with the increase of the tangential velocity,the KH instability evolves faster,hence the global density gradients,the TNE strength and area increase in the initial stage and achieve their peak earlier,and their maxima are higher for a larger tangential velocity.Physically,there are several competitive mechanisms in the evolution of the KH instability.(i)The physical gradients increase and the TNE effects are strengthened as the interface is elongated.The local physical gradients decrease and the local TNE intensity is weakened on account of the dissipation and/or diffusion.(ii)The global heat flux intensity is promoted when the physical gradients increase.As the contact area expands,the heat exchange is enhanced and the global heat flux intensity increases.(iii)The global TNE intensity reduces with the decreasing of physical gradients and increase with the increasing of TNE area.(iv)The nonequilibrium area increases as the fluid interface is elongated and is widened because of the dissipation and/or diffusion.
基金supported by the Natural Science Foundation of Heilongjiang Province of China(Grant No.A201409)the Special Fund Project for Technology Innovation Talent of Harbin(Grant No.2013RFLXJ007)the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.201159)
文摘Developing a robust computational strategy to address the rich physical characteristic involved in the thermcdynamic effects on the cryogenic cavitation remains a challenge in research. The objective of the present study is to focus on developing mod- elling strategy to simulate cavitating flows in liquid nitrogen. For this purpose, numerical simulation over a 2D quarter caliber hydrofoil is investigated by calibrating cavitation model parameters and implementing the thermodynamic effects to the Zwart cavitation model. Experimental measurements of pressure and temperature are utilized to validate the extensional Zwart cavi- tation model. The results show that the cavitation dynamics characteristic under the cryogenic environment ale different from that under the isothermal conditions： the cryogenic case yields a substantially shorter cavity around the hydrofoil, and the pre- dicted pressure and temperature inside the cavity are steeper under the cryogenic conditions. Compared with the experimental data, the computational predictions with the modified evaporation and condensation parameters display better results than the default parameters from the room temperature liquids. Based on a wide range of computations and comparisons, the extension- al Zwart cavitation model may predict more accurately the quasi-steady cavitation over a hydrofoil in liquid nitrogen by pri- marily altering the evaporation rate near the leading edge and the condensation rate in the cavity closure region.
基金Supported by the Natural Science Foundation of China(11705106,12075143)the Scientific Innovation Foundation of the Higher Education Institutions of Shanxi Province(2020L0471,2020L0472)+2 种基金the Science Technology Plan Project of Datong City,China(2020153)the Science Foundation of Shanxi Datong University(2022Q1,2015Q6,2022Q2)the Teaching Reform Project of Shanxi Datong University(XJG2022234)。
文摘Recently,some meaningful results have been obtained by studying the phase transition,critical exponents,and other thermodynamical properties of different black holes.Especially for the Anti-de Sitter(AdS)black holes,their thermodynamical properties nearby the critical point have attracted considerable attention.However,there exists little work on the thermodynamic properties of the de Sitter(dS)spacetime with black holes.In this paper,based on the effective thermodynamical quantities and the method of the Maxwell's equal-area law,we explore the phase equilibrium for the de Sitter spacetime with the charged black holes and the cloud of string and quintessence(i.e.,C-dSSQ spacetime).The boundaries of the two-phase coexistence region in both P_(eff)−T_(eff)and T_(eff)−S diagrams are obtained.The coexistent curve and the latent heat of phase transition for this system are also investigated.Furthermore,we analyze the effect of parameters(the state parameterωand the ratio of two horizon radii x=r+/r_(c))on the two-phase coexistence region boundary.The results indicate that the phase transition in C-dSSQ spacetime is analogous to that in a van der Waals fluid(vdw)system,which is determined by the electrical potential at the horizon.These results are helpful for understanding the basic properties of black holes and are also of great value for the establishment of quantum gravity.
