Localised forced ignition of globally stoichiometric stratified mixtures: A numerical investigation

Localised forced ignition of globally stoichiometric stratified mixtures (i.e. < φ > =1.0) has been analysed here based on direct numerical simulations for different initial values of velocity and equivalence ratio fluctuations (i.e. u′ and φ′), and the Taylor micro-scale l_φ of equivalence ratio φ variation. The localised ignition is accounted for by a source term in the energy transport equation which deposits energy over a stipulated time interval. It has been found that combustion takes place predominantly under premixed mode in the case of successful ignition. The initial values of φ′ and l_φ have been found to have significant effects on the extent of burning of stratified mixtures following localised ignition. It has been found that an increase in u′(φ′) has adverse effects on the burned gas mass, whereas the effects of l_φ on the extent of burning are non-monotonic and dependent on φ′. Detailed physical explanations have been provided for the observed u′, φ′ and l_φ dependences on the extent of burning in stratified mixtures.     

Ein Biprisma-Interferometer für 100 keV Elektronen und seine Anwendung

A biprism-interferometer for 100 keV electrons working with magnetic quadrupole lenses is described. With this instrument the mean inner potentials φ of Cu and Au were measured. Values of φ=(20,2± 0,7) V for Cu and φ=(16,8± 1,0) V for Au were found.     

一类类光测地线的加速度

类光测地线γ0(λ)与二维类空超曲面φ正交，λ为其仿射参量.假如在类光测地线γ0(λ)上存在一点r(r=γ0(λr))共轭于类空超曲面φ，则对于γ0(λ)上任一点q(q=γ0(λq))满足λq＞λr，一定能把γ0连续变形成一条从φ到q的类时曲线.当产生类时曲线的变分矢量场不是类光测地线上的广义Jacobi场时，这些类时曲线在趋于类光测地线时，它们的固有加速度趋于无穷大. 关键词： 类光测地线 共轭点 变分     

Josephson Current in f-Wave Superconductor/f-Wave Superconductor Junctions

We study the temperature T and the phase of the Josephson critical current I( φ ) by taking into account the roughness scattering effect at inerface in an f-wave superconductor (S)/Insulator layer (I)/f-wave superconductor (S) junction. It is found that the Josephson critical currents in f-wave S/f-wave S, the barrier strength and the roughness strength at inerface always suppress the Andreev reflection. When α =β, the phase dependence of theJosephson current I ( φ ) between two f-wave S is predicted to be sin φ; particularly, when α ≠β, the phase dependence of the Josephson current I( φ ) between two f-wave superconductors is not predicted to be sin φ and with the barrier strength increasing, the period of the I( φ ) turns decrease.     

Has the QCD critical point been signaled by observations at the BNL relativistic heavy ion collider?

The shear viscosity to entropy ratio (eta/s) is estimated for the hot and dense QCD matter created in Au+Au collisions at BNL Relativistic Heavy Ion Collider (square root[s_{NN}]=200 GeV). A very low value is found; eta/s approximately 0.1, which is close to the conjectured lower bound (1/4pi). It is argued that such a low value is indicative of thermodynamic trajectories for the decaying matter which lie close to the QCD critical end point.     

The big bang as a result of the first-order phase transition driven by a change of the scalar curvature in an expanding early Universe: The “hyperinflation” scenario

We suggest that the Big Bang could be a result of the first-order phase transition driven by a change in the scalar curvature of the 4D spacetime in an expanding cold Universe filled with a nonlinear scalar field φ and neutral matter with an equation of state p = νε (where p and ε are the pressure and energy density of the matter, respectively). We consider the Lagrangian of a scalar field with nonlinearity φ⁴ in a curved spacetime that, along with the term–ξR|φ|² quadratic in φ (where ξ is the interaction constant between the scalar and gravitational fields and R is the scalar curvature), contains the term ξRφ₀(φ + φ⁺) linear in φ, where φ₀ is the vacuum mean of the scalar field amplitude. As a consequence, the condition for the existence of extrema of the scalar-field potential energy is reduced to an equation cubic in φ. Provided that ν > 1/3, the scalar curvature R = [κ(3ν–1)ε–4Λ] (where κ and Λ are Einstein’s gravitational and cosmological constants, respectively) decreases with decreasing ε as the Universe expands, and a first-order phase transition in variable “external field” parameter proportional to R occurs at some critical value R _c < 0. Under certain conditions, the critical radius of the early Universe at the point of the first-order phase transition can reach an arbitrary large value, so that this scenario of unrestricted “inflation” of the Universe may be called “hyperinflation.” After the passage through the phase-transition point, the scalar-field potential energy should be rapidly released, which must lead to strong heating of the Universe, playing the role of the Big Bang.     

Gravitating global monopoles in extra dimensions and the braneworld concept

Multidimensional configurations with a Minkowski external spacetime and a spherically symmetric global monopole in extra dimensions are discussed in the context of the braneworld concept. The monopole is formed with a hedgehoglike set of scalar fields φⁱ with a symmetry-breaking potential V depending on the magnitude φ² = φⁱφⁱ. All possible kinds of globally regular configurations are singled out without specifying the shape of V(φ). These variants are governed by the maximum value φ_m of the scalar field, characterizing the energy scale of symmetry breaking. If φ_m < φ_cr (where φ_cr is a critical value of φ related to the multidimensional Planck scale), the monopole reaches infinite radii, whereas in the “strong field regime,” when φ_m ≥ φ_cr, the monopole may end with a finite-radius cylinder or have two regular centers. The warp factors of monopoles with both infinite and finite radii may either exponentially grow or tend to finite constant values far from the center. All such configurations are shown to be able to trap test scalar matter, in striking contrast to RS2 type five-dimensional models. The monopole structures obtained analytically are also found numerically for the Mexican hat potential with an additional parameter acting as a cosmological constant.     

Brownian dynamics simulation of monolayer formation by deposition of colloidal particles: A kinetic study at high bulk particle concentration

Brownian dynamics simulations (BDS) of sedimentation and irreversible adsorption of colloidal particles on a planar surface were carried out at bulk particle volume fractions (φ) in the range 0.05 to 0.25. The sedimentation and adsorption of colloidal particles were simulated as a non-sequential process that allows simultaneous settling and adsorption of particles. A kinetic model for the formation of particle monolayers based on the available surface fraction (θ ( A )) is proposed to predict simulation results. The simulations show a value of 0.625 for the maximum fractional surface coverage (θ (∞)) and a monolayer structure insensitive to φ. However, the kinetic order of the monolayer formation process has a strong dependence with φ, changing from a value close to a unit, at low φ, to a value around two at high φ. This change in the kinetic reaction order is associated to differences of particle adsorption mechanism on the surface. At low φ values, the monolayer formation is achieved by independent adsorption of single particles and the reaction order is close to 1. At high φ values, the simultaneous adsorption of two particles on the surface leads to an increase of the reaction order to values close to 2.     

Local anisotropy in globally isotropic granular packings

We report on two-dimensional computer simulations of frictionless granular packings at various area fractions φ above the jamming point φ(c). We measure the anisotropy in coarse-grained stress ε(s) and shear modulus ε(m) as functions of coarse-graining scale, R. ε(s) can be collapsed onto a master curve after rescaling R by a characteristic length scale ξ and ε(s) by an anisotropy magnitude A. Both A and ξ accelerate as φ→φ(c) from above, consistent with a divergence at φ(c). ε(m) shows no characteristic length scale and has a nontrivial power-law form, ε(m)~R(-0.62), over almost the entire range of R at all φ. These results suggest that the force chains present in the spatial structure of the quenched stress may be governed by different physics than the anomalous elastic response near jamming.     

Effective exponents for de almeida-thouless line

The experimental irreversibility line at the magnetic phase diagram H-T of spin glasses is often approximated using a power law Hα (T_G-T)^φ/2. The mean field theory of de Almeida and Thouless predicts φ=3 for temperatures T close to the spin-glass transition temperature T_G . For a range of reduced temperature involved in an experiment one should use, however, effective exponents (φ>3) obtained by fitting the power law to the exact expression for de Almeida-Thouless line. These compare favorably with experimental values of φ obtained for different spin glasses. The increase of effective exponent up to φ=7 on approaching the spin-glass-ferromagnetism multicritical point is also considered.     

Global and heliolatitude indices of solar activity and cosmic ray modulation

The time variation of the galactic cosmic rays (GCR) (1958–2006) is described using solar activity indices in the form Z^α, Z^α exp[?(φ/φ₀)^β], where Z and φ are one of the solar activity indices and the heliolatitude of sunspots; α, β, and φ₀ are the optimum parameters found by the least-squares method. The time variation of the GCR flux is satisfactorily described, the role of the active region heliolatitude in the index in relation to the cosmic ray modulation is revealed.     

Hadrons in hot and dense matter

I discuss our current understanding of the properties of hot and dense hadronic matter in equilibrium and its excitation spectrum. The latter allows for an experimental study of matter under extreme conditions through ‘in-medium spectroscopy’.     

光谱位相干涉仪参数的优化选取

模拟研究了光谱位相相干直接电场重构法的三个主要参数：时间延迟τ、频率剪切量Ω和展宽器色散φ之间的相互关系.研究结果表明：不同的待测脉冲，具有不同的最佳时间延迟τ；而τ的改变所引起的Ω的改变又限制了τ的选取范围；在此情况下只有适当调整φ才能在τ的较宽的范围内保证测量精度. 关键词： 光谱位相相干直接电场重构法 飞秒脉冲测量 光谱相干     

Superconducting vortex line in Josephson junction

The superconducting ring closed with the half infinite plane Josephson junction is considered. The external magnetic flux is introduced in the ring with the external source supplied solenoid.The conditions of stability are found for the superconducting vortex in the plane Josephson junction. The function φ(φ_x) is derived. Here φ is the total magnetic flux in the hole. This function differentiates from the same function in the case of the ring closed. with the point contact.     

Dirac vector model and variational treatments of proton spin-spin coupling across three bonds

The Dirac vector model and variational treatments have been used to study the angular dependence of proton spin couplings across three bonds in fragments of the type H-X-Y-H (X, Y = C, N, O). These couplings can be expressed by means of the relation J(φ) = A + B cos φ + C cos² φ, where φ is the dihedral angle and A, B and C are constants. It is seen that the behaviour of various fragments towards substituents can be qualitatively predicted by looking at the sign of the constant B.     

关于狭义相对论本质的十个论据

为寻找狭义相对论的本质,我们逐渐积累了10个论据,在量子力学基础上集中到一个基本假设:一个粒子总是不纯的,它总是包含着两个对立的场,φ(x,t)与χ(x,t),它们耦合在一起,并服从如下的对称性:φ(-x,-t)χ(x,t),χ(-x,-t)φ(x,t)。在一个粒子态中因|φ|>|χ|,φ占主导地位,但随着粒子速度增长,隐藏的χ场随之增大,这导致各种奇异的狭义相对论效应。在新定义的空一时反演(x-x,t-t)下,因φ(x,t)φ(-x,-t)=χc(x,t),　χ(x,t)χ(-x,-t)=φc(x,t)而|χc|>|φc|,于是粒子便变为它的反粒子,具有同样的动量与(正的)能量。上述对称性应当作为构造狭义相对论,相对论性量子力学,量子场论和粒子物理的出发点,其中关于中微子的超光速理论又是特别有兴趣的。     

矢量介子φ的动力学模型及耦合常数fφKK2,fωKK2与fρKK2的值

假设矢量介子φ(Ι=0,ι=1,m_φ=7.30m_π)是K散射交换ρ,ω以及φ介子本身而形成的共振。应用双色散关系中的N/D方法,并设ρ,ω以及交换的φ介子的质量为已知,近似求出KK的分波散射振幅。当要求该振幅能重新给出正确的共振位置(φ的质量)和宽度时,即可得出偶合常数f_φKK²、f_ωKK²与f_ρKK²所必需满足的关系,从而给出它们可能取的数值。     

Partonic Flow and phi-Meson production in Au+Au collisions at sqrt radical sNN = 200 GeV

We present first measurements of the phi-meson elliptic flow (v2(pT)) and high-statistics pT distributions for different centralities from radical sNN=200 GeV Au+Au collisions at RHIC. In minimum bias collisions the v2 of the phi meson is consistent with the trend observed for mesons. The ratio of the yields of the Omega to those of the phi as a function of transverse momentum is consistent with a model based on the recombination of thermal s quarks up to pT approximately 4 GeV/c, but disagrees at higher momenta. The nuclear modification factor (R CP) of phi follows the trend observed in the K S 0 mesons rather than in Lambda baryons, supporting baryon-meson scaling. These data are consistent with phi mesons in central Au+Au collisions being created via coalescence of thermalized s quarks and the formation of a hot and dense matter with partonic collectivity at RHIC.     

关于狭义相对论本质的十个论据(英文)

为寻找狭义相对论的本质,我们逐渐积累了10个论据,在量子力学基础上集中到一个基本假设:一个粒子总是不纯的,它总是包含着两个对立的场,φ(x,t)与χ(x,t),它们耦合在一起,并服从如下的对称性:φ(-x,-t)χ(x,t),χ(-x,-t)φ(x,t)。在一个粒子态中因|φ|>|χ|,φ占主导地位,但随着粒子速度增长,隐藏的χ场随之增大,这导致各种奇异的狭义相对论效应。在新定义的空一时反演(x-x,t-t)下,因φ(x,t)φ(-x,-t)=χc(x,t),　χ(x,t)χ(-x,-t)=φc(x,t)而|χc|>|φc|,于是粒子便变为它的反粒子,具有同样的动量与(正的)能量。上述对称性应当作为构造狭义相对论,相对论性量子力学,量子场论和粒子物理的出发点,其中关于中微子的超光速理论又是特别有兴趣的。