Modelling of turbulent scalar flux in turbulent premixed flames based on DNS databases

A transport equation for scalar flux in turbulent premixed flames was modelled on the basis of DNS databases. Fully developed turbulent premixed flames were obtained for three different density ratios of flames with a single-step irreversible reaction, while the turbulent intensity was comparable to the laminar burning velocity. These DNS databases showed that the countergradient diffusion was dominant in the flame region. Analyses of the Favre-averaged transport equation for turbulent scalar flux proved that the pressure related terms and the velocity–reaction rate correlation term played important roles on the countergradient diffusion, while the mean velocity gradient term, the mean progress variable gradient term and dissipation terms suppressed it. Based on these analyses, modelling of the combustion-related terms was discussed. The mean pressure gradient term and the fluctuating pressure term were modelled by scaling, and these models were in good agreement with DNS databases. The dissipation terms and the velocity–reaction rate correlation term were also modelled, and these models mimicked DNS well.     

Broken conformal ward identities in non-abelian gauge theories

Integrated broken conformal Ward identities for non-abelian gauge theories are derived. There exist anomalous terms linked to the ones in the Callan-Symanzik equations. Also there is a gauge dependent term that can be predicted classically and a new term involving Faddeev-Popov ghosts. These two terms cannot be neglected asymptotically relative to the other terms for gauge variant Greens functions.     

Structural properties of a TM polarized Gaussian beam in the far-field

In the far-field, the TM polarized Gaussian beam is just a sum of two orthogonal terms: the TE and the TM terms. The analytical expressions for the ratios of the powers of the TE and the TM terms to that of the TM polarized Gaussian beam are obtained without any approximation. The contributions of the powers of the TE and TM terms to the power of the TM polarized Gaussian beam only depend on the f-parameter. The analytical divergence angles of the TE term, the TM term, and the TM polarized Gaussian beam are derived. The formulae of the kurtosis parameters of the TE term, the TM term, and the TM polarized Gaussian beam are also presented. The divergence angles and the kurtosis parameters are only determined by the f-parameter. Relations among the divergence angles and the kurtosis parameters of the TE term, the TM term, and the TM polarized Gaussian beam are presented, respectively. The influence of the f-parameter on the ratios of the powers of the TE and the TM terms to the power of the TM polarized Gaussian beam, the far-field divergence angles, and the kurtosis parameters are numerically analyzed.     

Far-field divergence of a vectorial plane wave diffracted by a circular aperture from the vectorial structure

Based on the vectorial structure of an electromagnetic wave, the analytical and concise expressions for the TE and TM terms of a vectorial plane wave diffracted by a circular aperture are derived in the far-field. The expressions of the energy flux distributions of the TE term, the TM term and the diffracted plane wave are also presented. The ratios of the power of the TE and TM terms to that of the diffracted plane wave are examined in the far-field. In addition, the far-field divergence angles of the TE term, the TM term and the diffracted plane wave, which are related to the energy flux distribution, are investigated. The different energy flux distributions of the TE and TM terms result in the discrepancy of their divergence angles. The influences of the linearly polarized angle and the radius of the circular aperture on the far-field divergence angles of the TE term, the TM term and the diffracted plane wave are discussed in detail. This research may promote the recognition of the optical propagation through a circular aperture.vspace1mm     

KdV孤子的含时微扰理论

研究了周期性含时微扰对KdV(Korteweg de Vries)孤子的影响. 将微扰项展为时间变量的傅里叶级数,发现其常数项是导致长期项的根源. 在一阶近似下,消除长期项,求出了孤子参数(高度、宽度和速度)随时间的缓慢变化. 傅氏级数中的其他项决定了微扰对孤子波形的一阶修正. 关键词： KdV孤子 孤子微扰论     

Model for gravity at large distances

We construct an effective model for gravity of a central object at large scales. To leading order in the large radius expansion we find a cosmological constant, a Rindler acceleration, a term that sets the physical scales, and subleading terms. All these terms are expected from general relativity, except for the Rindler term. The latter leads to an anomalous acceleration in geodesics of test particles.     

Vectorial Structure of Non-Paraxial Linearly Polarized Gaussian Beam in Far Field

According to the vectorial structure of non-paraxial electromagnetic beams and the method of stationary phase, the analytical TE and TM terms of non-paraxial linearly polarized Caussian beam are presented in the far field. The influence of linearly polarized angle on the relative energy flux distributions of the whole beam and its TE and TM terms is studied. The beam spot of the TE term is perpendicular to the direction of linearly polarized angle, while that of the TM term coincides with the direction of linearly polarized angle. The whole beam spot is elliptical, and the long axis is located at the direction of linearly polarized angle. The relative energy flux distribution of the TE term is relatively centralized in the direction perpendicular to the linearly polarized angle. While that of the TM term is relatively centralized in the direction of linearly polarized angle. To obtain the isolated TM and TE terms, a polarizer should be put at the long and the short axis of the whole beam spot, respectively.     

Finite-width corrections to the Nambu action for the Nielsen-Olesen string

The finite-width correction terms to the Nambu action for Nielsen-Olesen strings are calculated. They consist of an extrinsic curvature squared or rigidity term and a new “twist” term. The extrinsic curvature term prevents cusps forming, rounding them off with a curvature radius of the order of the string width.     

Thermal Squeezed State Representation of Scalar Field and Energy Density in Semiclassical Theory of Gravity

The semiclassical theory of gravity is studied in terms of representation of scalar field in thermal coherent state and thermal squeezed state formalisms. For the FRW cosmological model with a minimal scalar field, the semiclassical Einstein equation reduces to zero-point energy term plus a finite temperature term and classical term in thermal coherent state. In thermal squeezed vacuum state it reduces to quantum term in addition to the finite temperature term and zero-point energy term. The present study can account for nonclassical state and finite temperature effect contributions to energy density in semiclassical theory of gravity.     

Flexural rigidity of a liquid surface

The energy of a mass of liquid is evaluated asymptotically in powers of the range of the intermolecular potential divided by a typical dimension of the liquid. The leading term is the internal energy, proportional to the liquid volume. The second term is the energy of surface tension, proportional to the area of the liquid surface. The third term is proportional to an integral over this surface of the square of the mean curvature of the surface minus one-third of its Gaussian curvature. This new term has exactly the form of the bending energy of a thin elastic plate. Comparing it with the bending energy yields expressions for the flexural rigidity and the Poisson ratio of the liquid surface. This flexural rigidity of the surface leads to new terms in the equation of equilibrium of the liquid surface, in addition to the usual surface tension terms.     

Response function of the plastic track detector CR-39

From available experimental data a general response function of CR-39 was derived, which has a linear and a supra-linear term with different temperature dependence. The factor of the supralinear term can be expressed in terms of the linear term which governs the response function in the low REL range. Therefore it is possible to establish the response function by means of alpha particles only.     

A note on analytical solutions of nonlinear fractional 2D heat equation with non-local integral terms

In this paper, we consider the (2+1) nonlinear fractional heat equation with non-local integral terms and investigate two different cases of such non-local integral terms. The first has to do with the time-dependent non-local integral term and the second is the space-dependent non-local integral term. Apart from the nonlinear nature of these formulations, the complexity due to the presence of the non-local integral terms impelled us to use a relatively new analytical technique called q-homotopy analysis method to obtain analytical solutions to both cases in the form of convergent series with easily computable components. Our numerical analysis enables us to show the effects of non-local terms and the fractional-order derivative on the solutions obtained by this method.     

Higher-order radiative perturbation theory

As a computationally effective tool, the first-order term of the radiative perturbation theory has been computed successfully, and has been applied in a number of areas. In this article, we develop the computational expressions for the higher-order terms of the perturbation expansion in a plane parallel atmosphere. These expressions are then implemented, and numerical results for some typical cases are presented. These results indicate that the computation is successful and that the higher-order terms are essential in cases where the first-order term alone cannot predict the perturbation with sufficient accuracy.     

应用"Maple"数学软件来推求同科电子光谱项

推求光谱项对于研究原子的结构和光谱十分重要.怎样确定复杂的多电子原子体系的光谱项是原子物理学研究的重要内容之一.受泡利原理的限制,含有多个同科电子的原子电子组态的光谱项的推求一直是原子物理学,结构化学等学科研究的难点,人工方法推求其谱项困难很大.本文根据同科电子在L-S耦合下量子数取值的组合特点,推出了总轨道磁量子数为ML时出现次数的计算公式,结合Maple数学软件,给出了一种推求同科电子光谱项的新方法.根据该公式,使用Maple数学软件,能快速、准确的求得同科电子在L-S耦合下的光谱项.文中我们举例应用该方法,具体推求了同科电子体系d3,f7电子组态在L-S耦合下的光谱项,所得结果与文献给出的一致.     

Gauge invariant theories of the generalized chiral Schwinger model

The gauge invariant theories of the generalized chiral Schwinger model are constructed in terms of two schemes with and without Wess-Zumino terms, respectively. Following the former scheme, we calculate the Wess-Zumino term which cancels the gauge anomaly, and then constitute the gauge invariant theory by adding the Wess-Zumino term to the original Lagrangian of the model. According to the latter, we modify the original Hamiltonian by adding a term composed of constraints of the model. It is so designed that the theory described by the modified Hamiltonian and its corresponding first-order Lagrangian maintains gauge invariance. We show by the canonical Dirac method that each of the two gauge invariant theories has the same physical spectrum as that of the original gauge noninvariant formulation.     

Gauge invariant theories of the generalized chiral Schwinger model

The gauge invariant theories of the generalized chiral Schwinger model are constructed in terms of two schemes with and without Wess-Zumino terms, respectively. Following the former scheme, we calculate the Wess-Zumino term which cancels the gauge anomaly, and then constitute the gauge invariant theory by adding the Wess-Zumino term to the original Lagrangian of the model. According to the latter, we modify the original Hamiltonian by adding a term composed of constraints of the model. It is so designed that the theory described by the modified Hamiltonian and its corresponding first-order Lagrangian maintains gauge invariance. We show by the canonical Dirac method that each of the two gauge invariant theories has the same physical spectrum as that of the original gauge noninvariant formulation.     

Coarsely grained stochastic Boltzmann equation and its moment equations

The stochastic Boltzmann equation is coarsely grained. The coarsely grained stochastic (CGS) Boltzmann equation has fluctuating terms in its collision term. On the basis of the CGS Boltzmann equation, reduced Grad’s 26 moment equations are derived. Coarsely grained moment equations obtained from the CGS Boltzmann equation show that fluctuating terms remain as nonvanishing terms owing to the nonlinearity in the collision term of the CGS Boltzmann equation. The Navier-Stokes-Fourier law obtained using the CGS Boltzmann equation indicates that the pressure deviator and heat flux include fluctuations of their one-order higher moments.     

推求等效组态的原子谱项波函数

本文提出了推求复杂组态Ｌ－Ｓ耦合谱项波函数的系统方法，着重解决了推求多重谱项的谱项波函数这一难题，运用ＰＡＳＣＡＬ语言编制了计算程序，利用本程序可快速、准确地求出等效组态的ｓ＾Ｎ，ｐ＾Ｎ，ｄ＾Ｎ，ｇ＾Ｎ，ｉ＾Ｎ，ｋ＾Ｎ的Ｌ－Ｓ耦合谱项和谱项波函数     

Gravity with propagating pseudoscalar torsion

The ECSK torsional theory of gravitation admits a new lagrangian term. The term introduces a propagating torsion potential in a manner which seems more motivated than other similar approaches. Also, unlike approaches involving similar new terms, no new physical constants need be introduced. The long-range effects of the new field are very small.     

Application of a time-dependent density-matrix formalism

An extended time-dependent Hartree-Fock theory which includes the effects of nucleon-nucleon collisions is presented and applied to the small-amplitude quadrupole motions of¹⁶O and⁴⁰Ca. The collision term of the theory includes not only the Born term but also higher-order terms. It is found that the higher-order terms are essential to the damping of the motions.