Nonequilibrium statistical theory of fracture is a theory of fracture that macromechanical quantities can be derived from the microscopic atomic mechanism of microcrack(or microvoid)evolution kinetcs by means of noneq...Nonequilibrium statistical theory of fracture is a theory of fracture that macromechanical quantities can be derived from the microscopic atomic mechanism of microcrack(or microvoid)evolution kinetcs by means of nonequilibrium statistical physical concepts and methods. The microcrack evolution equation is the central equation in the theory.The coefficents of the equation, the microcrack growth rate and the microcrack nucleation rate,come from microscopic atomic mechanism.The solution of the equation connects with macromechanical quantities by the model of the weakest chain. All the other formulas and quantities, for instance, distribution function,fracture probability, reliability, failure rate and macromechanical quantities such as strength, toughness, life etc. and their statistical distribution function and statistical fluctuation are derived in a unified fashion and expressed by a few physical parameters. This theory can be widely applied to various kinds of fracture, such as the brittle, fatigue, delayed and environmental fracture of metals and structural ceramics. The theoretical framework of this theory is given in this paper.展开更多
In this study, a constitutive model based on microscopic physical mechanism of silicone rubber foams was established. A theoretical statistical model of rubber elasticity considering the effect of dangling chains was ...In this study, a constitutive model based on microscopic physical mechanism of silicone rubber foams was established. A theoretical statistical model of rubber elasticity considering the effect of dangling chains was modified to build this model. When a strain amplification factor （X） was introduced, the theoretical model could fit the tensile stress-strain data of mono- and bi-modal foam matrix well （Adj. R-Square = 0.9989, 0.9983）. Parameters related to the polymer network, namely, average molecular weight （Me） and volume fraction （Ф） of chain segments between adjacent cross-linking points （network strands）, were calculated by probabilistic method from the number-average molecular weight （Mn）, vinyl content （wvi） of the primary polysiloxanes and percent conversion （q） of vinyl groups. The primary and infinite strain amplification factors （X0, X∞） and decay exponent （z）, introduced by X and related to the nanoparticles, were obtained by fitting. Inspired by the fact that the actual strain of matrix was lower than that of the foams＇, we introduced another item, strain hysteresis item （H, related with the foam porosity and cell structure）, into the statistical model as well. With the same above values of Mc, Ф, X0 and X∞, the model could also fit the compressive stress-strain data of mono- and bi-modal foams well （Adj. R-Square = 0.9948, 0.9985）. Interestingly, the strain hysteresis items of the mono- and bi-modal foams almost completely coincided under all experimental strains, which may be attributed to the almost equal porosity and similar cell structure of the two foams. This constitutive model may connect the macroscopic stress-strain behaviour to the parameters of microscopic molecular structures, promisingly providing a basis for the performance improvement and optimization of silicone rubber foams.展开更多
Based on collection and arrangement of evaluation indicators of soundscape in a forest park,24 primary evaluation indicators are chosen by grey statistical theory.The results show that there are 5 main factors influen...Based on collection and arrangement of evaluation indicators of soundscape in a forest park,24 primary evaluation indicators are chosen by grey statistical theory.The results show that there are 5 main factors influencing soundscape in a forest park,including water soundscape,wind soundscape,animal soundscape,recreation soundscape,and artificial soundscape,which contain 13 evaluation indicators.Among these factors,natural sound elements account for 84.6%.Thus a comprehensive evaluation indicator system of soundscape(including natural and unnatural soundscape) in a forest park is constructed by the selected evaluation indicators,and it is expected to provide a reference for scientific and systematic construction and development of forest parks in future.展开更多
This paper develops the non-equilibrium statistical fatigue damage theory to study the statistical behaviour of micro-crack for metals in magnetic field. The one-dimensional homogeneous crack system is chosen for stud...This paper develops the non-equilibrium statistical fatigue damage theory to study the statistical behaviour of micro-crack for metals in magnetic field. The one-dimensional homogeneous crack system is chosen for study. To investigate the effect caused by magnetic field on the statistical distribution of micro-crack in the system, the theoretical analysis on microcrack evolution equation, the average length of micro-crack, density distribution function of microcrack and fatigue fracture probability have been performed. The derived results relate the changes of some quantities, such as average length, density distribution function and fatigue fracture probability, to the applied magnetic field, the magnetic and mechanical properties of metals. It gives a theoretical explanation on the change of fatigue damage due to magnetic fields observed by experiments, and presents an analytic approach on studying the fatigue damage of metal in magnetic field.展开更多
A new approach was employed to calculate the canonical (thermal) rate constant basedon unified statistical theory. All information for the calculation was obtained from ab initio meth-ods. The flux integral for any po...A new approach was employed to calculate the canonical (thermal) rate constant basedon unified statistical theory. All information for the calculation was obtained from ab initio meth-ods. The flux integral for any point of reaction coordinate was calculated by counting the numberof quantum states and applied to determine the dividing surfaces along the intrinsic reaction coor-dinate (IRC). The classical exchange reaction H2+H, as an example, was investigated. The IRC forthe reaction has been traced and detailed information of IRC was carried out at the QCISD/6-311 G** level .The calculated rate constants are well consistent with the experimental results.展开更多
Understanding the thermodynamic behavior of complex fluids in confined environments is critical for various industrial and natural processes including but not limited to polymer flooding enhanced oil recovery(EOR).In ...Understanding the thermodynamic behavior of complex fluids in confined environments is critical for various industrial and natural processes including but not limited to polymer flooding enhanced oil recovery(EOR).In this work,we develop Atif-V2.0,an extended classical density functional theory(cDFT)framework that integrates the interfacial statistical associating fluid theory(iSAFT)to model multicomponent associating fluids composed of water-soluble polymers,alkanes,and water.Building on the original theoretical framework of Atif for modeling nanoconfined inhomogeneous fluids,Atif-V2.0 embeds explicit solvent and captures additional physical interactions-hydrogen bonding,which are critical in associating fluid systems.The other key feature of Atif-V2.0 is its ability to account for polymer topology.We demonstrate its capability by predicting the equilibrium structure and thermodynamic behavior of branched hydrolyzed polyacrylamide solutions near hard walls with various branching topologies,which provides a robust theoretical tool for the rational design of EOR polymers.展开更多
1H NMR chemical shifts of binary aqueous mixtures of acylamide, alcohol, dimethyl sulphoxide (DMSO), and acetone are correlated by statistical associating fluid theory (SAFT) association model. The comparison between ...1H NMR chemical shifts of binary aqueous mixtures of acylamide, alcohol, dimethyl sulphoxide (DMSO), and acetone are correlated by statistical associating fluid theory (SAFT) association model. The comparison between SAPT association model and Wilson equation shows that the former is better for dealing with aqueous solutions. Finally, the specialties of both models are discussed.展开更多
In order to study the influence of microstructural texture on the growth of short fatigue cracks in metals, the nonequilibrium statistical theory of fatigue fracture correlating a microscopic mechanism with the macros...In order to study the influence of microstructural texture on the growth of short fatigue cracks in metals, the nonequilibrium statistical theory of fatigue fracture correlating a microscopic mechanism with the macroscopic properties is modified to take into consideration the microstructural features of a material, thereby allowing a rationalisation of the experimental data of short fatigue crack growth and long fatigue crack growth. The nonequilibrium statistical theory thus developed relates the growth of cracks with a dislocation mechanism to simulate short fatigue crack growth with the long fatigue crack growth behaviour and predicts the fatigue crack growth rates throughout the fatigue lifetime. The results is finally compared with that of other fatigue theories.展开更多
With the rapid development of higher education in China,colleges and universities are facing new challenges and impacts in talent training.Probability Theory and Mathematical Statistics is one of the important courses...With the rapid development of higher education in China,colleges and universities are facing new challenges and impacts in talent training.Probability Theory and Mathematical Statistics is one of the important courses in higher education for science and engineering majors and economics and management majors.Its critical role in cultivating students’thinking skills and improving their problem-solving skills is self-evident.Course ideological and political education construction is an important link in college talent training work.Combining ideological and political education with course teaching can help students establish correct value concepts and play a certain role in improving their comprehensive ability and quality.At present,the construction of ideological and political education in the Probability Theory and Mathematical Statistics course still faces some problems,mainly manifested in the lack of attention paid by teachers to course ideological and political education,insufficient exploitation of ideological and political elements,and the simplification of ideological and political education implementation methods.In order to comprehensively deepen the construction of course ideological and political education in line with the actual needs of Probability Theory and Mathematical Statistics course teaching,we should strengthen the construction of teacher teams,improve teachers’ability to carry out course ideological and political education,integrate educational resources,develop educational resources for ideological and political education,and innovate teaching methods to improve the overall effect of ideological and political education integration.展开更多
The generation of nonclassical photons via quantum light–matter interactions is of fundamental importance in quantum optics.Here we investigate steady-state two-photon correlation function and photon squeezing in an ...The generation of nonclassical photons via quantum light–matter interactions is of fundamental importance in quantum optics.Here we investigate steady-state two-photon correlation function and photon squeezing in an open anisotropic Rabi lattice by applying quantum dressed master equation embedded with the mean-field approximation.The expanded antibunching effect of photons due to anisotropic qubit–photon interaction,is strongly suppressed by including inter-site photon tunneling,whereas the giant photon bunching keeps robust with weak inter-site photon tunneling strength.The microscopic processes for photon antibunching and bunching effects are presented based on incoherent transitions between eigenstates.The photon squeezing is also analyzed under the influences of qubit–photon coupling and anisotropic factor.The quadrature squeezing shows persistency by tuning on the inter-site photon tunneling,and becomes dramatically pronounced at the small anisotropic factor.Moreover,the increasing number of qubits significantly enhances quadrature squeezing with strong qubit–photon interaction.We hope such results may provide physical insights into efficient generation and manipulation of nonclassical features of photons in quantum light–matter interacting lattice systems.展开更多
The properties of nonadiabatic trapping models of the reaction NH+H -N+H, are investigated in a collinear model as \veil as a non-collinear thermal reaction on the basis of theintrinsic reaction coordinate (IRC) intbr...The properties of nonadiabatic trapping models of the reaction NH+H -N+H, are investigated in a collinear model as \veil as a non-collinear thermal reaction on the basis of theintrinsic reaction coordinate (IRC) intbrmation obtained by ah initio calculations at QCISD/631 IG** ie\el. Using the unitied statistical theory fornonadiabatic trapping models. the thermal rateconstants over the temperature range of 2000-3000K are computed which are in excellent agreementwith the experiment results.展开更多
Using nonequilibrium statistical mechanics closure method, it is shown that the skewness factor of the velocity derivative of isotropic turbulence ap- proaches a constant -0.515 when the Reynolds number is very high, ...Using nonequilibrium statistical mechanics closure method, it is shown that the skewness factor of the velocity derivative of isotropic turbulence ap- proaches a constant -0.515 when the Reynolds number is very high, which is in agree- ment with the DNS (direct numerical simulation) result of Vincent and Meneguzzi (1991).展开更多
Statistical methods are commonly used to evaluate natural populations and environmental variables, yet these must recognize temporal trends in population character to be appropriate in an evolving world. New equations...Statistical methods are commonly used to evaluate natural populations and environmental variables, yet these must recognize temporal trends in population character to be appropriate in an evolving world. New equations presented here define the statistical measures of aggregate historical populations affected by linear changes in population means and standard deviations. These can be used to extract the statistical character of present-day populations, needed to define modern variability and risk, from tables of historical data that are dominated by measurements made when conditions were different. As an example, many factors such as climate change and in-channel structures are causing flood levels to rise, so realistic estimation of future flood levels must take such secular changes into account. The new equations provide estimates of water levels for ＂100-year＂ floods in the USA Midwest that are 0.5 to 2 m higher than official calculations that routinely assume population stationarity. These equations also show that flood levels will continue to rise by several centimeters per year. This rate is nearly ten times faster than the rise of sea level, and thus represents one of the fastest and most damaging rates of change that is documented by robust data.展开更多
With hydrogen-like impurity（HLI） located in the center of Cs I quantum pseudodot（QPD） and by using the variational method of Pekar type（VMPT）, we investigate the first-excited state energy（FESE）, excitation en...With hydrogen-like impurity（HLI） located in the center of Cs I quantum pseudodot（QPD） and by using the variational method of Pekar type（VMPT）, we investigate the first-excited state energy（FESE）, excitation energy and transition frequency of the strongly-coupled bound polaron in the present paper. Temperature effects on bound polaron properties are calculated by employing the quantum statistical theory（QST）. According to the present work＇s numerical results, the FESE, excitation energy and transition frequency decay（amplify） with raising temperature in the regime of lower（higher）temperature. They are decreasing functions of Coulomb impurity potential strength.展开更多
The issue of dropping the random force f(i) and the arbitrariness of choosing the basic variable in the variational approach to turbulence closure problem, pointed out recently by the Russian scientists Bazdenkov and ...The issue of dropping the random force f(i) and the arbitrariness of choosing the basic variable in the variational approach to turbulence closure problem, pointed out recently by the Russian scientists Bazdenkov and Kukharkin, are discussed. According to the mean-square estimation method, the random force f(i) should be dropped in the error expression of the LFP (Langevin-Fokker-Planck) model. However, f(i) is not neglected, its effect has been taken into account by the variational approach. In order to optimize the perturbation solution of the Liouville equation, the LFP model requires that the basic variable is as near to Gaussian as possible. Hence, the velocity, instead of the vorticity, should be chosen as the basic variable in the three-dimensional turbulence. Although the LFP model and the zero-order Gaussian term of PDF (probability density function) imply whiteness assumption (zero correlation time of f(i)), the higher-order non-Gaussian terms of PDF correspond to the nonwhiteness of turbulence dynamics, the variational approach does calculate the nonwhiteness effect properly.展开更多
Based on the unified Hauser–Feshbach and exciton model,which can describe the particle emission processes between discrete energy levels with energy,angular momentum,and parity conservations,a statistical theory of l...Based on the unified Hauser–Feshbach and exciton model,which can describe the particle emission processes between discrete energy levels with energy,angular momentum,and parity conservations,a statistical theory of light nucleus reaction(STLN)is developed to calculate the double-differential cross-sections of the outgoing neutron and light charged particles for the proton-induced^(6) Li reaction.A significant difference is observed between the p+^(6) Li and p+^(7) Li reactions owing to the discrepancies in the energy-level structures of the targets.The reaction channels,including sequential and simultaneous emission processes,are analyzed in detail.Taking the double-differential cross-sections of the outgoing proton as an example,the influence of contaminations(such as^(1) H,^(7)Li,^(12)C,and^(16)O)on the target is identified in terms of the kinetic energy of the first emitted particles.The optical potential parameters of the proton are obtained by fitting the elastic scattering differential cross-sections.The calculated total double-differential cross-sections of the outgoing proton and deuteron at E_(p)=14 MeV agree well with the experimental data for different outgoing angles.Simultaneously,the mixed double differential cross-sections of^(3) He andαare in good agreement with the measurements.The agreement between the measured data and calculated results indicates that the two-body and three-body breakup reactions need to be considered,and the pre-equilibrium reaction mechanism dominates the reaction processes.Based on the STLN model,a PLUNF code for the p+^(6) Li reaction is developed to obtain an ENDF-6-formatted file of the double-differential cross-sections of the nucleon and light composite charged particles.展开更多
A k ε PDF (probability density function) model based on a statistical theory for turbulent gas particle flows is proposed, and a numerical procedure combining the finite difference and finite fluctuating velocity...A k ε PDF (probability density function) model based on a statistical theory for turbulent gas particle flows is proposed, and a numerical procedure combining the finite difference and finite fluctuating velocity group methods is used. The obtained statistically averaged equations have the same form as that of the equations obtained by the Reynolds averaging. Using the k ε PDF model (PDF particle turbulence model combined with k ε gas turbulence model), many terms, such as the diffusion term in particle Reynolds stress equations, can be exactly calculated for verifying the second order moment model. The k ε PDF model is used to simulate gas particle flows behind a backward facing step. Comparison of the predictions using both k ε PDF and the k ε k p models with experimental results shows that the k ε PDF model gives more reasonable nonisotropic features of particle turbulence.展开更多
This paper investigates theoretically the influence of magnetization on fatigue life by using non-equilibrium statistical theory of fatigue fracture for metals. The fatigue microcrack growth rate is obtained from the ...This paper investigates theoretically the influence of magnetization on fatigue life by using non-equilibrium statistical theory of fatigue fracture for metals. The fatigue microcrack growth rate is obtained from the dynamic equation of microcrack growth, where the influence of magnetization is described by an additional term in the potential energy of microcrack. The statistical value of fatigue life of metal under magnetic field is derived, which is expressed in terms of magnetic field and macrophysical as well as microphysical quantities. The fatigue life of AISI 4140 steel in static magnetic field from this theory is basically consistent with the experimental data.展开更多
Deficiencies of applying the traditional least squares support vector machine （LS-SVM） to time series online prediction were specified. According to the kernel function matrix＇s property and using the recursive cal...Deficiencies of applying the traditional least squares support vector machine （LS-SVM） to time series online prediction were specified. According to the kernel function matrix＇s property and using the recursive calculation of block matrix, a new time series online prediction algorithm based on improved LS-SVM was proposed. The historical training results were fully utilized and the computing speed of LS-SVM was enhanced. Then, the improved algorithm was applied to timc series online prediction. Based on the operational data provided by the Northwest Power Grid of China, the method was used in the transient stability prediction of electric power system. The results show that, compared with the calculation time of the traditional LS-SVM（75 1 600 ms）, that of the proposed method in different time windows is 40-60 ms, proposed method is above 0.8. So the improved method is online prediction. and the prediction accuracy（normalized root mean squared error） of the better than the traditional LS-SVM and more suitable for time series online prediction.展开更多
文摘Nonequilibrium statistical theory of fracture is a theory of fracture that macromechanical quantities can be derived from the microscopic atomic mechanism of microcrack(or microvoid)evolution kinetcs by means of nonequilibrium statistical physical concepts and methods. The microcrack evolution equation is the central equation in the theory.The coefficents of the equation, the microcrack growth rate and the microcrack nucleation rate,come from microscopic atomic mechanism.The solution of the equation connects with macromechanical quantities by the model of the weakest chain. All the other formulas and quantities, for instance, distribution function,fracture probability, reliability, failure rate and macromechanical quantities such as strength, toughness, life etc. and their statistical distribution function and statistical fluctuation are derived in a unified fashion and expressed by a few physical parameters. This theory can be widely applied to various kinds of fracture, such as the brittle, fatigue, delayed and environmental fracture of metals and structural ceramics. The theoretical framework of this theory is given in this paper.
基金financially supported by the National Natural Science Foundation of China(Nos.51473151 and 51703210)
文摘In this study, a constitutive model based on microscopic physical mechanism of silicone rubber foams was established. A theoretical statistical model of rubber elasticity considering the effect of dangling chains was modified to build this model. When a strain amplification factor （X） was introduced, the theoretical model could fit the tensile stress-strain data of mono- and bi-modal foam matrix well （Adj. R-Square = 0.9989, 0.9983）. Parameters related to the polymer network, namely, average molecular weight （Me） and volume fraction （Ф） of chain segments between adjacent cross-linking points （network strands）, were calculated by probabilistic method from the number-average molecular weight （Mn）, vinyl content （wvi） of the primary polysiloxanes and percent conversion （q） of vinyl groups. The primary and infinite strain amplification factors （X0, X∞） and decay exponent （z）, introduced by X and related to the nanoparticles, were obtained by fitting. Inspired by the fact that the actual strain of matrix was lower than that of the foams＇, we introduced another item, strain hysteresis item （H, related with the foam porosity and cell structure）, into the statistical model as well. With the same above values of Mc, Ф, X0 and X∞, the model could also fit the compressive stress-strain data of mono- and bi-modal foams well （Adj. R-Square = 0.9948, 0.9985）. Interestingly, the strain hysteresis items of the mono- and bi-modal foams almost completely coincided under all experimental strains, which may be attributed to the almost equal porosity and similar cell structure of the two foams. This constitutive model may connect the macroscopic stress-strain behaviour to the parameters of microscopic molecular structures, promisingly providing a basis for the performance improvement and optimization of silicone rubber foams.
基金Supported by the National Key Technology R&D Program(2014BAD15B00)Science and Technology Project of Educational Commission of Fujian Province,China(JA15168)
文摘Based on collection and arrangement of evaluation indicators of soundscape in a forest park,24 primary evaluation indicators are chosen by grey statistical theory.The results show that there are 5 main factors influencing soundscape in a forest park,including water soundscape,wind soundscape,animal soundscape,recreation soundscape,and artificial soundscape,which contain 13 evaluation indicators.Among these factors,natural sound elements account for 84.6%.Thus a comprehensive evaluation indicator system of soundscape(including natural and unnatural soundscape) in a forest park is constructed by the selected evaluation indicators,and it is expected to provide a reference for scientific and systematic construction and development of forest parks in future.
文摘This paper develops the non-equilibrium statistical fatigue damage theory to study the statistical behaviour of micro-crack for metals in magnetic field. The one-dimensional homogeneous crack system is chosen for study. To investigate the effect caused by magnetic field on the statistical distribution of micro-crack in the system, the theoretical analysis on microcrack evolution equation, the average length of micro-crack, density distribution function of microcrack and fatigue fracture probability have been performed. The derived results relate the changes of some quantities, such as average length, density distribution function and fatigue fracture probability, to the applied magnetic field, the magnetic and mechanical properties of metals. It gives a theoretical explanation on the change of fatigue damage due to magnetic fields observed by experiments, and presents an analytic approach on studying the fatigue damage of metal in magnetic field.
文摘A new approach was employed to calculate the canonical (thermal) rate constant basedon unified statistical theory. All information for the calculation was obtained from ab initio meth-ods. The flux integral for any point of reaction coordinate was calculated by counting the numberof quantum states and applied to determine the dividing surfaces along the intrinsic reaction coor-dinate (IRC). The classical exchange reaction H2+H, as an example, was investigated. The IRC forthe reaction has been traced and detailed information of IRC was carried out at the QCISD/6-311 G** level .The calculated rate constants are well consistent with the experimental results.
基金financially supported by the Key Technologies R&D Program of China National Offshore Oil Corporation(No.KJGG2021-0504)。
文摘Understanding the thermodynamic behavior of complex fluids in confined environments is critical for various industrial and natural processes including but not limited to polymer flooding enhanced oil recovery(EOR).In this work,we develop Atif-V2.0,an extended classical density functional theory(cDFT)framework that integrates the interfacial statistical associating fluid theory(iSAFT)to model multicomponent associating fluids composed of water-soluble polymers,alkanes,and water.Building on the original theoretical framework of Atif for modeling nanoconfined inhomogeneous fluids,Atif-V2.0 embeds explicit solvent and captures additional physical interactions-hydrogen bonding,which are critical in associating fluid systems.The other key feature of Atif-V2.0 is its ability to account for polymer topology.We demonstrate its capability by predicting the equilibrium structure and thermodynamic behavior of branched hydrolyzed polyacrylamide solutions near hard walls with various branching topologies,which provides a robust theoretical tool for the rational design of EOR polymers.
基金Supported by the National Natural Science Foundation of China (No. 29976035)the Natural Science Foundation of Zhejiang Provincial (No. RC01051).
文摘1H NMR chemical shifts of binary aqueous mixtures of acylamide, alcohol, dimethyl sulphoxide (DMSO), and acetone are correlated by statistical associating fluid theory (SAFT) association model. The comparison between SAPT association model and Wilson equation shows that the former is better for dealing with aqueous solutions. Finally, the specialties of both models are discussed.
文摘In order to study the influence of microstructural texture on the growth of short fatigue cracks in metals, the nonequilibrium statistical theory of fatigue fracture correlating a microscopic mechanism with the macroscopic properties is modified to take into consideration the microstructural features of a material, thereby allowing a rationalisation of the experimental data of short fatigue crack growth and long fatigue crack growth. The nonequilibrium statistical theory thus developed relates the growth of cracks with a dislocation mechanism to simulate short fatigue crack growth with the long fatigue crack growth behaviour and predicts the fatigue crack growth rates throughout the fatigue lifetime. The results is finally compared with that of other fatigue theories.
基金2023 General Project of Philosophy and Social Science Research in Universities of Jiangsu Province“Exploration and Practice of Mixed Teaching Model Oriented by Curriculum Ideology and Politics in the Course of Probability Theory and Mathematical Statistics”(2023SJYB1499)。
文摘With the rapid development of higher education in China,colleges and universities are facing new challenges and impacts in talent training.Probability Theory and Mathematical Statistics is one of the important courses in higher education for science and engineering majors and economics and management majors.Its critical role in cultivating students’thinking skills and improving their problem-solving skills is self-evident.Course ideological and political education construction is an important link in college talent training work.Combining ideological and political education with course teaching can help students establish correct value concepts and play a certain role in improving their comprehensive ability and quality.At present,the construction of ideological and political education in the Probability Theory and Mathematical Statistics course still faces some problems,mainly manifested in the lack of attention paid by teachers to course ideological and political education,insufficient exploitation of ideological and political elements,and the simplification of ideological and political education implementation methods.In order to comprehensively deepen the construction of course ideological and political education in line with the actual needs of Probability Theory and Mathematical Statistics course teaching,we should strengthen the construction of teacher teams,improve teachers’ability to carry out course ideological and political education,integrate educational resources,develop educational resources for ideological and political education,and innovate teaching methods to improve the overall effect of ideological and political education integration.
基金Project supported by the National Natural Science Foundation of China(Grant No.11874011)the Opening Project of Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology.
文摘The generation of nonclassical photons via quantum light–matter interactions is of fundamental importance in quantum optics.Here we investigate steady-state two-photon correlation function and photon squeezing in an open anisotropic Rabi lattice by applying quantum dressed master equation embedded with the mean-field approximation.The expanded antibunching effect of photons due to anisotropic qubit–photon interaction,is strongly suppressed by including inter-site photon tunneling,whereas the giant photon bunching keeps robust with weak inter-site photon tunneling strength.The microscopic processes for photon antibunching and bunching effects are presented based on incoherent transitions between eigenstates.The photon squeezing is also analyzed under the influences of qubit–photon coupling and anisotropic factor.The quadrature squeezing shows persistency by tuning on the inter-site photon tunneling,and becomes dramatically pronounced at the small anisotropic factor.Moreover,the increasing number of qubits significantly enhances quadrature squeezing with strong qubit–photon interaction.We hope such results may provide physical insights into efficient generation and manipulation of nonclassical features of photons in quantum light–matter interacting lattice systems.
文摘The properties of nonadiabatic trapping models of the reaction NH+H -N+H, are investigated in a collinear model as \veil as a non-collinear thermal reaction on the basis of theintrinsic reaction coordinate (IRC) intbrmation obtained by ah initio calculations at QCISD/631 IG** ie\el. Using the unitied statistical theory fornonadiabatic trapping models. the thermal rateconstants over the temperature range of 2000-3000K are computed which are in excellent agreementwith the experiment results.
基金The project supported by the National Basic Research Program "Non-linear Science"
文摘Using nonequilibrium statistical mechanics closure method, it is shown that the skewness factor of the velocity derivative of isotropic turbulence ap- proaches a constant -0.515 when the Reynolds number is very high, which is in agree- ment with the DNS (direct numerical simulation) result of Vincent and Meneguzzi (1991).
文摘Statistical methods are commonly used to evaluate natural populations and environmental variables, yet these must recognize temporal trends in population character to be appropriate in an evolving world. New equations presented here define the statistical measures of aggregate historical populations affected by linear changes in population means and standard deviations. These can be used to extract the statistical character of present-day populations, needed to define modern variability and risk, from tables of historical data that are dominated by measurements made when conditions were different. As an example, many factors such as climate change and in-channel structures are causing flood levels to rise, so realistic estimation of future flood levels must take such secular changes into account. The new equations provide estimates of water levels for ＂100-year＂ floods in the USA Midwest that are 0.5 to 2 m higher than official calculations that routinely assume population stationarity. These equations also show that flood levels will continue to rise by several centimeters per year. This rate is nearly ten times faster than the rise of sea level, and thus represents one of the fastest and most damaging rates of change that is documented by robust data.
基金Project supported by the National Natural Science Foundation of China(Grant No.11464033)
文摘With hydrogen-like impurity（HLI） located in the center of Cs I quantum pseudodot（QPD） and by using the variational method of Pekar type（VMPT）, we investigate the first-excited state energy（FESE）, excitation energy and transition frequency of the strongly-coupled bound polaron in the present paper. Temperature effects on bound polaron properties are calculated by employing the quantum statistical theory（QST）. According to the present work＇s numerical results, the FESE, excitation energy and transition frequency decay（amplify） with raising temperature in the regime of lower（higher）temperature. They are decreasing functions of Coulomb impurity potential strength.
基金The work is supported by the National Basic Research Program "Non-linear Sciences the National Natural Science Foundation of China
文摘The issue of dropping the random force f(i) and the arbitrariness of choosing the basic variable in the variational approach to turbulence closure problem, pointed out recently by the Russian scientists Bazdenkov and Kukharkin, are discussed. According to the mean-square estimation method, the random force f(i) should be dropped in the error expression of the LFP (Langevin-Fokker-Planck) model. However, f(i) is not neglected, its effect has been taken into account by the variational approach. In order to optimize the perturbation solution of the Liouville equation, the LFP model requires that the basic variable is as near to Gaussian as possible. Hence, the velocity, instead of the vorticity, should be chosen as the basic variable in the three-dimensional turbulence. Although the LFP model and the zero-order Gaussian term of PDF (probability density function) imply whiteness assumption (zero correlation time of f(i)), the higher-order non-Gaussian terms of PDF correspond to the nonwhiteness of turbulence dynamics, the variational approach does calculate the nonwhiteness effect properly.
基金supported by the National Natural Science Foundation of China(No.12065003)the Guangxi Key R&D Project(2023AB07029)+1 种基金the Scientific Research and Technology Development Project of Guilin(20210104-2)the Central Government Guides Local Scientific and Technological Development Funds of China(Guike ZY22096024)。
文摘Based on the unified Hauser–Feshbach and exciton model,which can describe the particle emission processes between discrete energy levels with energy,angular momentum,and parity conservations,a statistical theory of light nucleus reaction(STLN)is developed to calculate the double-differential cross-sections of the outgoing neutron and light charged particles for the proton-induced^(6) Li reaction.A significant difference is observed between the p+^(6) Li and p+^(7) Li reactions owing to the discrepancies in the energy-level structures of the targets.The reaction channels,including sequential and simultaneous emission processes,are analyzed in detail.Taking the double-differential cross-sections of the outgoing proton as an example,the influence of contaminations(such as^(1) H,^(7)Li,^(12)C,and^(16)O)on the target is identified in terms of the kinetic energy of the first emitted particles.The optical potential parameters of the proton are obtained by fitting the elastic scattering differential cross-sections.The calculated total double-differential cross-sections of the outgoing proton and deuteron at E_(p)=14 MeV agree well with the experimental data for different outgoing angles.Simultaneously,the mixed double differential cross-sections of^(3) He andαare in good agreement with the measurements.The agreement between the measured data and calculated results indicates that the two-body and three-body breakup reactions need to be considered,and the pre-equilibrium reaction mechanism dominates the reaction processes.Based on the STLN model,a PLUNF code for the p+^(6) Li reaction is developed to obtain an ENDF-6-formatted file of the double-differential cross-sections of the nucleon and light composite charged particles.
文摘A k ε PDF (probability density function) model based on a statistical theory for turbulent gas particle flows is proposed, and a numerical procedure combining the finite difference and finite fluctuating velocity group methods is used. The obtained statistically averaged equations have the same form as that of the equations obtained by the Reynolds averaging. Using the k ε PDF model (PDF particle turbulence model combined with k ε gas turbulence model), many terms, such as the diffusion term in particle Reynolds stress equations, can be exactly calculated for verifying the second order moment model. The k ε PDF model is used to simulate gas particle flows behind a backward facing step. Comparison of the predictions using both k ε PDF and the k ε k p models with experimental results shows that the k ε PDF model gives more reasonable nonisotropic features of particle turbulence.
文摘This paper investigates theoretically the influence of magnetization on fatigue life by using non-equilibrium statistical theory of fatigue fracture for metals. The fatigue microcrack growth rate is obtained from the dynamic equation of microcrack growth, where the influence of magnetization is described by an additional term in the potential energy of microcrack. The statistical value of fatigue life of metal under magnetic field is derived, which is expressed in terms of magnetic field and macrophysical as well as microphysical quantities. The fatigue life of AISI 4140 steel in static magnetic field from this theory is basically consistent with the experimental data.
基金Project (SGKJ[200301-16]) supported by the State Grid Cooperation of China
文摘Deficiencies of applying the traditional least squares support vector machine （LS-SVM） to time series online prediction were specified. According to the kernel function matrix＇s property and using the recursive calculation of block matrix, a new time series online prediction algorithm based on improved LS-SVM was proposed. The historical training results were fully utilized and the computing speed of LS-SVM was enhanced. Then, the improved algorithm was applied to timc series online prediction. Based on the operational data provided by the Northwest Power Grid of China, the method was used in the transient stability prediction of electric power system. The results show that, compared with the calculation time of the traditional LS-SVM（75 1 600 ms）, that of the proposed method in different time windows is 40-60 ms, proposed method is above 0.8. So the improved method is online prediction. and the prediction accuracy（normalized root mean squared error） of the better than the traditional LS-SVM and more suitable for time series online prediction.
