A study on entanglement dynamics for a four-qubit model

In this paper, we consider the entanglement dynamics of a four-qubit model [2006 Phys. Rev. A 74 042328] where two entangled qubits a and b locally interact with separate qubits A and B via the spin-exchange-like Hamiltonian. We study the effect of purity of initial entangled state of qubits a, b on the entanglement evolution and its relation with energy transfer. Also, we find that the total bipartite entanglement of qubits a, b plus A, B is not a constant any longer when the initial entangled state of a, b is not pure, which is a complement to the result in the paper [2007 J. Phys. B 40 S45] for the pure case.     

Steady state speed distribution analysis for a combined cellular automaton traffic model

Cellular Automaton （CA） based traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain （DTMC） analytical framework for a Nagel-Schreckenberg and Fukui Ishibashi combined CA model （W^2H traffic flow model） from microscopic point of view to capture the macroscopic steady state speed distributions. The inter-vehicle spacing Maxkov chain and the steady state speed Markov chain are proved to be irreducible and ergodic. The theoretical speed probability distributions depending on the traffic density and stochastic delay probability are in good accordance with numerical simulations. The derived fundamental diagram of the average speed from theoretical speed distributions is equivalent to the results in the previous work.     

基于自相关函数的激光散斑统计半径的测量

为了测量激光散斑的统计半径,运用统计光学理论推导了二维近场散斑光强的归一化自相关函数,并提出了通过求解散斑图像自相关拟合函数的系数来计算激光散斑统计半径的一种测量方法,利用该测量方法编制的测量软件可以方便地计算出激光散斑的统计半径.通过对尺寸已知的模拟散斑的测量,测量结果与实际尺寸相吻合,证实了该测量方法的可行性.     

Bridge density functional approximation for non-uniform hard core repulsive Yukawa fluid

In this work, a bridge density functional approximation （BDFA） （J. Chem. Phys. 112, 8079 （2000）） for a nonuniform hard-sphere fluid is extended to a non-uniform hard-core repulsive Yukawa （HCRY） fluid. It is found that the choice of a bulk bridge functional approximation is crucial for both a uniform HCRY fluid and a non-uniform HCRY fluid. A new bridge functional approximation is proposed, which can accurately predict the radial distribution function of the bulk HCRY fluid. With the new bridge functional approximation and its associated bulk second order direct correlation function as input, the BDFA can be used to well calculate the density profile of the HCRY fluid subjected to the influence of varying external fields, and the theoretical predictions are in good agreement with the corresponding simulation data. The calculated results indicate that the present BDFA captures quantitatively the phenomena such as the coexistence of solid-like high density phase and low density gas phase, and the adsorption properties of the HCRY fluid, which qualitatively differ from those of the fluids combining both hard-core repulsion and an attractive tail.     

降低轴流风机噪声的两种方法

本文对轴流风机的噪声源进行了理论和实验分析,对降低风机噪声的方法进行了总结。在此基础上,研究了降低风机噪声的两种新方法——叶片不等距分布方法和叶片穿孔方法。理论分析和实验结果表明,这两种方法为降低轴流风机噪声提供了新的途径。     

一类二阶渐近周期微分方程的正同宿轨道

§ 1　IntroductionIn this note we are concerned with the asymptotically periodic second order equation-u″+α( x) u =β( x) uq +γ( x) up,　 x∈ R,( 1 )where1 相似文献   

传递系统的伪分解函数和应用

令X为一个紧致度量空间,fX→X为(拓扑)传递的映射.通过对传递系统(X,f)在fn,n∈N的作用下的伪分解,先引入一个新的拓扑不变量"传递系统的PD函数(伪分解函数)".然后,讨论关于此不变量的一些重要性质.最后,把关于周期轨道的Sharkovskii定理推广到传递子系统上.     

一种时序逻辑网络的快速设计方法

引用1984年尹克震提出的“开关函数的反演公式”,采用伪随机序列技术的思想,提出移位寄存器型时序逻辑网络的一种快速设计方法。     

On the differentiability of depth distribution function of deposited energy, momentum and ion range

Based on the translational invariance of a medium,a new theorem has been proposed and proved rigorously:the depth distributions of the deposited energy,momentum and ion range must be infinitely differentiable functions in amorphous or polycrystalline infinite targets by ion bombardment,if these functions exist.The origin of the “discontinuity”,derived by Dr Glazov in 1995 in J.Phys.:Condens.Matter 7 6365,has been analysed in detail.For the power cross section,neglecting electronic stopping,the linear transport equations determining the depth distribution functions of the deposited energy and monentum (by taking the threshold enerkgy into account )have been solved asymptotically.An important formula derived by Dr Glazov has been confirmed and generalized.The results agree with the new theorem.