The goal of this paper is to quantitatively formulate some necessary conditions for the development of intense atmospheric vortices. Specifically, these criteria are discussed for tropical cyclones (TC) and polar lo...The goal of this paper is to quantitatively formulate some necessary conditions for the development of intense atmospheric vortices. Specifically, these criteria are discussed for tropical cyclones (TC) and polar lows (PL) by using bulk formulas for fluxes of momentum, sensible heating, and latent heating between the ocean and the atmosphere. The velocity scale is used in two forms: (1) as expressed through the buoyancy flux b and the Coriolis parameter Ic for rotating fluids convection, and (2) as expressed with the cube of velocity times the drag coefficient through the formula for total kinetic energy dissipation in the atmospheric boundary layer. In the quasistationary case the dissipation equals the generation of the energy. In both cases the velocity scale can be expressed through temperature and humidity differences between the ocean and the atmosphere in terms of the reduced gravity, and both forms produce quite comparable velocity scales. Using parameters b and Ic, we can form scales of the area and, by adding the mass of a unit air column, a scale of the total kinetic energy as well. These scales nicely explain the much smaller size of a PL, as compared to a TC, and the total kinetic energy of a TC is of the order 1018 - 1019 J. It will be shown that wind of 33 m s^-1 is produced when the total enthalpy fluxes between the ocean and the atmosphere are about 700 W m-2 for a TC and 1700 W m-2 for a PL, in association with the much larger role of the latent heat in the first case and the stricter geostrophic constraints and larger static stability in the second case. This replaces the mystical role of 26℃ as a criterion for TC origin. The buoyancy flux, a product of the reduced gravity and the wind speed, together with the atmospheric static stability, determines the rate of the penetrating convection. It is known from the observations that the formation time for a PL reaching an altitude of 5-6 km can be only a few hours, and a day, or even half a day, for a TC reaching 15-18 km. These two facts allow us to construct curves on the plane of Ts and ΔT = Ts - Ta to determine possibilities for forming an intense vortex. Here, Ta is the atmospheric temperature at the height z = 10 m. A PL should have AT 〉 20℃ in accordance with the observations and nmnerical simulations. The conditions for a TC are not so straightforward but our diagram shows that the temperature difference of a few degrees, or possibly even a fraction of a degree, might be sufficient for TC development for a range of static stabilities and development times.展开更多
The correlation of the scaled energy,e = Es/ Mo, versus earthquake magnitude, Ms, is studied based on two models: (1) Model 1 based on the use of the time function of the average displacements, with a ω^-2 source ...The correlation of the scaled energy,e = Es/ Mo, versus earthquake magnitude, Ms, is studied based on two models: (1) Model 1 based on the use of the time function of the average displacements, with a ω^-2 source spectrum, across a fault plane; and (2) Model 2 based on the use of the time function of the average displacements, with a ω^-3 source spectrum, across a fault plane. For the second model, there are two cases: (a) As ζ= T, where r is the rise time and T the rupture time, lg(e) - -Ms; and (b) As ζ 〈〈 T, lg(e)- -(1/2)Ms. The second model leads to a negative value of e. This means that Model 2 cannot work for studying the present problem. The results obtained from Model 1 suggest that the source model is a factor, yet not a unique one, in controlling the correlation of e versus Ms.展开更多
The three-dimensional nonlinear quasi-geostrophic potential vorticity equation is reduced to a linear form in the stream function in spherical coordinates for the permanent wave solutions consisting of zonal wavenumbe...The three-dimensional nonlinear quasi-geostrophic potential vorticity equation is reduced to a linear form in the stream function in spherical coordinates for the permanent wave solutions consisting of zonal wavenumbers from 0 to n and rn vertical components with a given degree n.This equation is solved by treating the coefficient of the Coriolis parameter square in the equation as the eigenvalue both for sinusoidal and hyperbolic variations in vertical direction. It is found that these solutions can represent the observed long term flow patterns at the surface and aloft over the globe closely. In addition, the sinusoidal vertical solutions with large eigenvalue G are trapped in low latitude,and the scales of these trapped modes are longer than 10 deg. lat. even for the top layer of the ocean and hence they are much larger than that given by the equatorial β-plane solutions.Therefore such baroclinic disturbances in the ocean can easily interact with those in the atmosphere.Solutions of the shallow water potential vorticity equation are treated in a similar manner but with the effective depth H=RT/g taken as limited within a small range for the atmosphere.The propagation of the flow energy of the wave packet consisting of more than one degree is found to be along the great circle around the globe both for barotropic and for baroclinic flows in the atmosphere.展开更多
Guest Editor in Chief:Professor Xiao-Ping Zhang, University of Birmingham The potential for renewable energy to make contributions to mitigating the impact of climate change is expected to increase significantly in th...Guest Editor in Chief:Professor Xiao-Ping Zhang, University of Birmingham The potential for renewable energy to make contributions to mitigating the impact of climate change is expected to increase significantly in the longer term. Renewable energy generation technologies including onshore wind, offshore wind, wave,tidal, marine current, and ocean thermal energy generation as well as PV power generation, which are considered展开更多
A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_4(KTP) crystal. The tuning range was observed intermittently from 0.96 ...A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_4(KTP) crystal. The tuning range was observed intermittently from 0.96 THz to 1.87 THz,from 3.04 THz to 3.33 THz, from 4.17 THz to 4.48 THz, from 4.78 THz to 4.97 THz, from 5.125 THz to 5.168 THz, from5.44 THz to 5.97 THz, and from 6.74 THz to 7.01 THz. The dual-Stokes wavelengths resonance phenomena were observed in some certain tuning angle ranges. Through the theoretical analysis of the dispersion curve of the KTP crystal, the intermittent THz wave tuning range and dual-wavelength Stokes waves operation during angle tuning process were explained.The theoretical analysis was in good agreement with the experiment results. The maximum THz output voltage detected by Golay cell was 1.7 V at 5.7 THz under the pump energy of 210 mJ, corresponding to the THz wave output energy of5.47 μJ and conversion efficiency of 2.6 × 10^(-5).展开更多
We study the energy scaling of terahertz (THz) emission through difference frequency generation of near-infrared pulses, and demonstrate that Gigawatt few-cycle THz transients at the central frequency of 30 THz are pr...We study the energy scaling of terahertz (THz) emission through difference frequency generation of near-infrared pulses, and demonstrate that Gigawatt few-cycle THz transients at the central frequency of 30 THz are produced from GaSe crystal pumped by two pulses at 1.65 and 1.95 micrometers, with the high quantum yield of 28%. Our analysis indicates that the high yield of DFG originates from the largely reduced group velocity mismatch as the long-wavelength pumping pulses are employed.展开更多
We examine the validity of the ACDM model and probe the dynamics of dark energy with the latest astronomical observations. Using the Ore(z) diagnosis, we find that various kinds of observational data are in tension ...We examine the validity of the ACDM model and probe the dynamics of dark energy with the latest astronomical observations. Using the Ore(z) diagnosis, we find that various kinds of observational data are in tension within the ACDM framework. We then allow for dynamics of dark energy and investigate the constraint on dark energy parameters. We find that for two different kinds of parametri- sations of the equation of state parameter w, a combination of current data mildly favours an evolving w, although the significance is not sufficient for it to be supported by Bayesian evidence. A forecast of the DESI survey shows that the dynamics of dark energy could be detected at the 7σ confidence level and would be decisively supported by Bayesian evidence, if the best-fit model of w derived from current data is the true model.展开更多
A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic mo...A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic model. The hydrostatic approximation was abandoned and the simple energy ( E e ) closure scheme was used in both models. Using the two models, characteristics of PBL structure and its evolution were fully studied. The main characteristic of the PBL is the circulation, and it fairly affects the distribution of the pollutant in the pit.展开更多
This fairy tale begins with the journey of the famous Zhuang Zhou dreaming of a butterfly: I often do not know whether I am living in a dream, dreaming of a butterfly, or is a butterfly dreaming of me? Furthermore, th...This fairy tale begins with the journey of the famous Zhuang Zhou dreaming of a butterfly: I often do not know whether I am living in a dream, dreaming of a butterfly, or is a butterfly dreaming of me? Furthermore, there is the saying that those who believe it will see it, while for those who see it, it is then too late to believe it. The first thing I believe in is the holographic principle, and the holographic dark energy brought about by the holographic principle. Not until last year, I began to believe that there must be a new energy scale in between the Planck scale and the standard model scale. I also believe that this new scale is related to the minimal axion model. The results of the journey described in this paper are the following: 1. There is a new energy scale, which we will call the intermediate energy scale,and the best choice is 1012Ge V. 2. The minimal axion exists, and under the new scale, there is no new physics. The axion plays both the roles of inflation and dark matter. New physics between the new scale and the Planck scale may exist because in this energy range, quantum gravity becomes important. 3. The dark energy is holographic dark energy. Then all of the observable effects of all three predictions about dark energy, dark matter, and cosmic inflation are to be observed.展开更多
Based on image strip dividing, an effective and fast image retargeting algorithm is proposed for resizing images. First,we construct the image energy map using gradient magnitude of the pixels and calculate the accumu...Based on image strip dividing, an effective and fast image retargeting algorithm is proposed for resizing images. First,we construct the image energy map using gradient magnitude of the pixels and calculate the accumulated energy of each column,dividing the image into several strips by integrating similar energy columns. The reduced amount of dimension is decided in inverse proportion to the average energy for each strip. Then we retarget the image combining scaling with cropping in terms of each strip's reduced ratio. Experiment results show that the proposed algorithm is capable of implementing fast image retargeting and preserving both the local structures and the global visual effect of the image.展开更多
Observations show that Type Ia supernovae (SNe Ia) are dimmer than ex- pected from a matter dominated Universe. It has been suggested that this observed phenomenon can also be explained using light absorption instea...Observations show that Type Ia supernovae (SNe Ia) are dimmer than ex- pected from a matter dominated Universe. It has been suggested that this observed phenomenon can also be explained using light absorption instead of dark energy. However, there is a serious degeneracy between the cosmic absorption parameter and the present matter density parameter Ωm when one tries to place constraints on the cosmic opacity using SNe Ia data. We combine the latest baryon acoustic oscillation (BAO) and Union2 SNe Ia data in order to break this degeneracy. Assuming a fiat ACDM model, we find that, although an opaque Universe is favored by SNe Ia+BAO since the best fit value of the cosmic absorption parameter is larger than zero, fire = 1 is ruled out at the 99.7% confidence level. Thus, cosmic opacity is not sufficient to account for the present observations and dark energy or modified gravity is still re- quired.展开更多
Molecular simulation was performed to study the interaction between CaCO3 crystal and several oligomer inhibitors, by using the equilibrium morphology method to calculate the growth morphology of CaCO3 without inhibit...Molecular simulation was performed to study the interaction between CaCO3 crystal and several oligomer inhibitors, by using the equilibrium morphology method to calculate the growth morphology of CaCO3 without inhibitors. The calculated morphology agreed well with SEM photographs. Then, a double-layer model was built to investigate the interaction between calcite crystal and oligomer inhibitors containing maleic anhydride (MA) and acrylic acid (AA). Interaction energy per gram of an oligomer inhibitor was introduced as a scale of inhibition efficiency of different monomers. The results indicated that, for calcite scale inhibition, acrylamide (AM) and vinyl phosphonic acid (VPA) were the most efficient monomers, while allylsulfonic acid (AS) was the poorest. Increasing proportion of AM in dimer inhibitor molecule would improve the inhibition efficiency of MA, though, for a trimer, such as MA-AA-AM, certain sequence of monomers in the inhibitor molecule was necessary besides higher proportion of AM.展开更多
In this study,a persistent heavy rainfall event(PHRE) that lasted for around 9 days(from 0000 UTC 17 to0000 UTC 26 June 2010) and caused accumulated precipitation above 600 mm over the Yangtze River valley,was rea...In this study,a persistent heavy rainfall event(PHRE) that lasted for around 9 days(from 0000 UTC 17 to0000 UTC 26 June 2010) and caused accumulated precipitation above 600 mm over the Yangtze River valley,was reasonably reproduced by the advanced research WRF model.Based on the simulation,a set of energy budget equations that divided the real meteorological field into the mean and eddy flows were calculated so as to understand the interactions between the precipitation-related eddy flows and their background circulations(BCs).The results indicated that the precipitation-related eddy flows interacted with their BCs intensely during the PHRE.At different layers,the energy cycles showed distinct characteristics.In the upper troposphere,downscaled energy cascade processes appeared,which favored the maintenance of upper-level eddy flows;whereas,a baroclinic energy conversion,which reduced the upper-level jet,also occurred.In the middle troposphere,significant upscaled energy cascade processes,which reflect the eddy flows' reactionary effects on their BCs,appeared.These effects cannot be ignored with respect to the BCs' evolution,and the reactionary effects were stronger in the dynamical field than in the thermodynamical field.In the lower troposphere,a long-lived quasi-stationary lower-level shear line was the direct trigger for the PHRE.The corresponding eddy flows were sustained mainly through the baroclinic energy conversion associated with convection activities.Alongside this,the downscaled energy cascade processes of kinetic energy,which reflect the direct influences of BCs on the precipitation-related eddy flows,were also favorable.A downscaled energy cascade of exergy also appeared in the lower troposphere,which favored the precipitation-related eddy flow indirectly via the baroclinic energy conversion.展开更多
A vast body of fusion data has been analyzed for different projectiles and target nuclei. It is indicated that the sub-barrier fusion depends on the fusion Q-value. In terms of a recently introduced fusion Q-value rul...A vast body of fusion data has been analyzed for different projectiles and target nuclei. It is indicated that the sub-barrier fusion depends on the fusion Q-value. In terms of a recently introduced fusion Q-value rule and an energy scaling reduction procedure, the experimental fusion excitation functions are reduced and compared with each other. It is found that the reduced fusion excitations of selected fusion systems show a similar trend. The fusion data for massive nuclei are in agreement with the Q-value rule. In the fusion process, the Q contribution should be considered. Within this approach, the sub-barrier fusion cross sections of most fusion systems can be predicted without involving any structure effects of colliding nuclei. Instances of disagreement are presented in a few fusion systems. The use of the energy scaling as a criterion of possible experimental data inconsistency is discussed. More precise experimental fusion data need to be measured.展开更多
基金the grant of the RF President SS4166 2006.5the Program of the Presidium of RAS"Mathematical Methods of Nonlinear Dynamics"
文摘The goal of this paper is to quantitatively formulate some necessary conditions for the development of intense atmospheric vortices. Specifically, these criteria are discussed for tropical cyclones (TC) and polar lows (PL) by using bulk formulas for fluxes of momentum, sensible heating, and latent heating between the ocean and the atmosphere. The velocity scale is used in two forms: (1) as expressed through the buoyancy flux b and the Coriolis parameter Ic for rotating fluids convection, and (2) as expressed with the cube of velocity times the drag coefficient through the formula for total kinetic energy dissipation in the atmospheric boundary layer. In the quasistationary case the dissipation equals the generation of the energy. In both cases the velocity scale can be expressed through temperature and humidity differences between the ocean and the atmosphere in terms of the reduced gravity, and both forms produce quite comparable velocity scales. Using parameters b and Ic, we can form scales of the area and, by adding the mass of a unit air column, a scale of the total kinetic energy as well. These scales nicely explain the much smaller size of a PL, as compared to a TC, and the total kinetic energy of a TC is of the order 1018 - 1019 J. It will be shown that wind of 33 m s^-1 is produced when the total enthalpy fluxes between the ocean and the atmosphere are about 700 W m-2 for a TC and 1700 W m-2 for a PL, in association with the much larger role of the latent heat in the first case and the stricter geostrophic constraints and larger static stability in the second case. This replaces the mystical role of 26℃ as a criterion for TC origin. The buoyancy flux, a product of the reduced gravity and the wind speed, together with the atmospheric static stability, determines the rate of the penetrating convection. It is known from the observations that the formation time for a PL reaching an altitude of 5-6 km can be only a few hours, and a day, or even half a day, for a TC reaching 15-18 km. These two facts allow us to construct curves on the plane of Ts and ΔT = Ts - Ta to determine possibilities for forming an intense vortex. Here, Ta is the atmospheric temperature at the height z = 10 m. A PL should have AT 〉 20℃ in accordance with the observations and nmnerical simulations. The conditions for a TC are not so straightforward but our diagram shows that the temperature difference of a few degrees, or possibly even a fraction of a degree, might be sufficient for TC development for a range of static stabilities and development times.
基金sponsored by Academia Sinica and the National Science Council(under Grant No.NSC101-2119-M-001-01)
文摘The correlation of the scaled energy,e = Es/ Mo, versus earthquake magnitude, Ms, is studied based on two models: (1) Model 1 based on the use of the time function of the average displacements, with a ω^-2 source spectrum, across a fault plane; and (2) Model 2 based on the use of the time function of the average displacements, with a ω^-3 source spectrum, across a fault plane. For the second model, there are two cases: (a) As ζ= T, where r is the rise time and T the rupture time, lg(e) - -Ms; and (b) As ζ 〈〈 T, lg(e)- -(1/2)Ms. The second model leads to a negative value of e. This means that Model 2 cannot work for studying the present problem. The results obtained from Model 1 suggest that the source model is a factor, yet not a unique one, in controlling the correlation of e versus Ms.
文摘The three-dimensional nonlinear quasi-geostrophic potential vorticity equation is reduced to a linear form in the stream function in spherical coordinates for the permanent wave solutions consisting of zonal wavenumbers from 0 to n and rn vertical components with a given degree n.This equation is solved by treating the coefficient of the Coriolis parameter square in the equation as the eigenvalue both for sinusoidal and hyperbolic variations in vertical direction. It is found that these solutions can represent the observed long term flow patterns at the surface and aloft over the globe closely. In addition, the sinusoidal vertical solutions with large eigenvalue G are trapped in low latitude,and the scales of these trapped modes are longer than 10 deg. lat. even for the top layer of the ocean and hence they are much larger than that given by the equatorial β-plane solutions.Therefore such baroclinic disturbances in the ocean can easily interact with those in the atmosphere.Solutions of the shallow water potential vorticity equation are treated in a similar manner but with the effective depth H=RT/g taken as limited within a small range for the atmosphere.The propagation of the flow energy of the wave packet consisting of more than one degree is found to be along the great circle around the globe both for barotropic and for baroclinic flows in the atmosphere.
文摘Guest Editor in Chief:Professor Xiao-Ping Zhang, University of Birmingham The potential for renewable energy to make contributions to mitigating the impact of climate change is expected to increase significantly in the longer term. Renewable energy generation technologies including onshore wind, offshore wind, wave,tidal, marine current, and ocean thermal energy generation as well as PV power generation, which are considered
基金Project supported by the National Basic Research Program of China(Grant Nos.2015CB755403 and 2014CB339802)the National Key Research and Development Program of China(Grant No.2016YFC0101001)+2 种基金the National Natural Science Foundation of China(Grant Nos.61775160,61771332,and 61471257)China Postdoctoral Science Foundation(Grant No.2016M602954)Postdoctoral Science Foundation of Chongqing,China(Grant No.Xm2016021)
文摘A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_4(KTP) crystal. The tuning range was observed intermittently from 0.96 THz to 1.87 THz,from 3.04 THz to 3.33 THz, from 4.17 THz to 4.48 THz, from 4.78 THz to 4.97 THz, from 5.125 THz to 5.168 THz, from5.44 THz to 5.97 THz, and from 6.74 THz to 7.01 THz. The dual-Stokes wavelengths resonance phenomena were observed in some certain tuning angle ranges. Through the theoretical analysis of the dispersion curve of the KTP crystal, the intermittent THz wave tuning range and dual-wavelength Stokes waves operation during angle tuning process were explained.The theoretical analysis was in good agreement with the experiment results. The maximum THz output voltage detected by Golay cell was 1.7 V at 5.7 THz under the pump energy of 210 mJ, corresponding to the THz wave output energy of5.47 μJ and conversion efficiency of 2.6 × 10^(-5).
基金Supported by the National Natural Science Foundation of China under Grant Nos 11274326,61221064,61405222,11134010 and 11127901the Shanghai Sailing Program under Grant No 14YF1406200
文摘We study the energy scaling of terahertz (THz) emission through difference frequency generation of near-infrared pulses, and demonstrate that Gigawatt few-cycle THz transients at the central frequency of 30 THz are produced from GaSe crystal pumped by two pulses at 1.65 and 1.95 micrometers, with the high quantum yield of 28%. Our analysis indicates that the high yield of DFG originates from the largely reduced group velocity mismatch as the long-wavelength pumping pulses are employed.
基金supported by the National Natural Science Foundation of China(Grant No.11673025)a Key International Collaboration Grant from the Chinese Academy of SciencesGBZ is also supported by a Royal Society Newton Advanced Fellowship
文摘We examine the validity of the ACDM model and probe the dynamics of dark energy with the latest astronomical observations. Using the Ore(z) diagnosis, we find that various kinds of observational data are in tension within the ACDM framework. We then allow for dynamics of dark energy and investigate the constraint on dark energy parameters. We find that for two different kinds of parametri- sations of the equation of state parameter w, a combination of current data mildly favours an evolving w, although the significance is not sufficient for it to be supported by Bayesian evidence. A forecast of the DESI survey shows that the dynamics of dark energy could be detected at the 7σ confidence level and would be decisively supported by Bayesian evidence, if the best-fit model of w derived from current data is the true model.
文摘A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic model. The hydrostatic approximation was abandoned and the simple energy ( E e ) closure scheme was used in both models. Using the two models, characteristics of PBL structure and its evolution were fully studied. The main characteristic of the PBL is the circulation, and it fairly affects the distribution of the pollutant in the pit.
基金supported by a grant from the National Natural Science Foundation of China: 12175099。
文摘This fairy tale begins with the journey of the famous Zhuang Zhou dreaming of a butterfly: I often do not know whether I am living in a dream, dreaming of a butterfly, or is a butterfly dreaming of me? Furthermore, there is the saying that those who believe it will see it, while for those who see it, it is then too late to believe it. The first thing I believe in is the holographic principle, and the holographic dark energy brought about by the holographic principle. Not until last year, I began to believe that there must be a new energy scale in between the Planck scale and the standard model scale. I also believe that this new scale is related to the minimal axion model. The results of the journey described in this paper are the following: 1. There is a new energy scale, which we will call the intermediate energy scale,and the best choice is 1012Ge V. 2. The minimal axion exists, and under the new scale, there is no new physics. The axion plays both the roles of inflation and dark matter. New physics between the new scale and the Planck scale may exist because in this energy range, quantum gravity becomes important. 3. The dark energy is holographic dark energy. Then all of the observable effects of all three predictions about dark energy, dark matter, and cosmic inflation are to be observed.
文摘Based on image strip dividing, an effective and fast image retargeting algorithm is proposed for resizing images. First,we construct the image energy map using gradient magnitude of the pixels and calculate the accumulated energy of each column,dividing the image into several strips by integrating similar energy columns. The reduced amount of dimension is decided in inverse proportion to the average energy for each strip. Then we retarget the image combining scaling with cropping in terms of each strip's reduced ratio. Experiment results show that the proposed algorithm is capable of implementing fast image retargeting and preserving both the local structures and the global visual effect of the image.
基金supported by the National Natural Science Foundation of China(Grant Nos. 10935013, 11175093, 11222545 and 11075083)Zhejiang Provincial Natural Science Foundation of China (Grant Nos. Z6100077 and R6110518)+6 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of PR China (FANEDD, Grant No. 200922)the National Basic Research Program of China (973 program, Grant No. 2010CB832803)the Program for New Century Excellent Talents in University (NCET, Grant No. 09-0144)the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT, Grant No. IRT0964)Hunan Provincial Natural Science Foundation of China (Grant No. 11JJ7001)the Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP, Grant No. 20124306110001)the Program for the Key Discipline in Hunan Province
文摘Observations show that Type Ia supernovae (SNe Ia) are dimmer than ex- pected from a matter dominated Universe. It has been suggested that this observed phenomenon can also be explained using light absorption instead of dark energy. However, there is a serious degeneracy between the cosmic absorption parameter and the present matter density parameter Ωm when one tries to place constraints on the cosmic opacity using SNe Ia data. We combine the latest baryon acoustic oscillation (BAO) and Union2 SNe Ia data in order to break this degeneracy. Assuming a fiat ACDM model, we find that, although an opaque Universe is favored by SNe Ia+BAO since the best fit value of the cosmic absorption parameter is larger than zero, fire = 1 is ruled out at the 99.7% confidence level. Thus, cosmic opacity is not sufficient to account for the present observations and dark energy or modified gravity is still re- quired.
基金Financial support from the National Natural Science Foundation of China (No.50773063)National Basic Research Program of China(2010CB635111)Basic Research of National Defence are highly appreciated
文摘Molecular simulation was performed to study the interaction between CaCO3 crystal and several oligomer inhibitors, by using the equilibrium morphology method to calculate the growth morphology of CaCO3 without inhibitors. The calculated morphology agreed well with SEM photographs. Then, a double-layer model was built to investigate the interaction between calcite crystal and oligomer inhibitors containing maleic anhydride (MA) and acrylic acid (AA). Interaction energy per gram of an oligomer inhibitor was introduced as a scale of inhibition efficiency of different monomers. The results indicated that, for calcite scale inhibition, acrylamide (AM) and vinyl phosphonic acid (VPA) were the most efficient monomers, while allylsulfonic acid (AS) was the poorest. Increasing proportion of AM in dimer inhibitor molecule would improve the inhibition efficiency of MA, though, for a trimer, such as MA-AA-AM, certain sequence of monomers in the inhibitor molecule was necessary besides higher proportion of AM.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2012CB417201)National Natural Science Foundation of China(41375053 and 41505038)
文摘In this study,a persistent heavy rainfall event(PHRE) that lasted for around 9 days(from 0000 UTC 17 to0000 UTC 26 June 2010) and caused accumulated precipitation above 600 mm over the Yangtze River valley,was reasonably reproduced by the advanced research WRF model.Based on the simulation,a set of energy budget equations that divided the real meteorological field into the mean and eddy flows were calculated so as to understand the interactions between the precipitation-related eddy flows and their background circulations(BCs).The results indicated that the precipitation-related eddy flows interacted with their BCs intensely during the PHRE.At different layers,the energy cycles showed distinct characteristics.In the upper troposphere,downscaled energy cascade processes appeared,which favored the maintenance of upper-level eddy flows;whereas,a baroclinic energy conversion,which reduced the upper-level jet,also occurred.In the middle troposphere,significant upscaled energy cascade processes,which reflect the eddy flows' reactionary effects on their BCs,appeared.These effects cannot be ignored with respect to the BCs' evolution,and the reactionary effects were stronger in the dynamical field than in the thermodynamical field.In the lower troposphere,a long-lived quasi-stationary lower-level shear line was the direct trigger for the PHRE.The corresponding eddy flows were sustained mainly through the baroclinic energy conversion associated with convection activities.Alongside this,the downscaled energy cascade processes of kinetic energy,which reflect the direct influences of BCs on the precipitation-related eddy flows,were also favorable.A downscaled energy cascade of exergy also appeared in the lower troposphere,which favored the precipitation-related eddy flow indirectly via the baroclinic energy conversion.
基金Supported by National Nature Science Foundation of China(11475013,11035007,11175011)State Key Laboratory of Software Development Environment(SKLSDE-2014ZX-08)Fundamental Research Funds for the Central Universities and the Key Laboratory of High Precision Nuclear Spectroscopy,Institute of Modern Physics,Chinese Academy of Sciences
文摘A vast body of fusion data has been analyzed for different projectiles and target nuclei. It is indicated that the sub-barrier fusion depends on the fusion Q-value. In terms of a recently introduced fusion Q-value rule and an energy scaling reduction procedure, the experimental fusion excitation functions are reduced and compared with each other. It is found that the reduced fusion excitations of selected fusion systems show a similar trend. The fusion data for massive nuclei are in agreement with the Q-value rule. In the fusion process, the Q contribution should be considered. Within this approach, the sub-barrier fusion cross sections of most fusion systems can be predicted without involving any structure effects of colliding nuclei. Instances of disagreement are presented in a few fusion systems. The use of the energy scaling as a criterion of possible experimental data inconsistency is discussed. More precise experimental fusion data need to be measured.