脉冲电流烧结Al2O3颗粒的广义热弹性分析

脉冲电流烧结过程的颈部形成机理,特别是非导电粉末材料,是需要着重研究的核心问题。以非导电Al_2O_3粉末为研究对象,引入L-S(Lord and Shulman)型广义热弹性方程,初步探究烧结初期非导电粉末颈部局部高温形成以及快速烧结机理。利用Comsol Multiphysics模拟得到脉冲电流烧结过程中颗粒内部的温度场和应力场分布以及烧结颈部的化学势和空位浓度变化规律。数值结果表明,热以波的形式在烧结颈部产生叠加,形成局部高温。化学势变化表明:烧结初期表面扩散占主要作用,空位浓度差的突变使烧结颈部产生局部空位浓度梯度,促进烧结颈长过程,缩短烧结时间。     

热力学平衡中的假想态浅议

在热力学平衡中,假想态概念可拓展应用于稀溶液中溶质化学势等温式的推导、非均相体系中平衡常数的计算及电化学体系中电极电势的求算等。     

A Model Study of Equation of State of QCD at Finite Chemical Potential and Zero Temperature

In this paper, we give a direct method for calculating the partition function, and hence the equation of state （EOS） of QCD at finite chemical potential and zero temperature. In the EOS derived in this paper the pressure density is the sum of two terms： the first term P（μ）｜μ=0 （the pressure density at μ = 0） is a μ-independent constant; the second term, which is totally determined by G[μ] （p） （the dressed quark propagator at finite μ）, contains all the nontrivial μ-dependence. By applying a general result in the rainbow-ladder approximation of the Dyson-Schwinger approach obtained in our previous study [Phys. Rev. C 71 （2005） 015205], G[μ]（p） is calculated from the meromorphic quark propagator proposed in [Phys. Rev. D 67 （2003） 054019]. From this the full analytic expression of the EOS of QCD at finite μ and zero T is obtained （apart from the constant term P（μ）｜μ=0, which can in principle be caJculated from the CJT effective action）. A comparison between our EOS and the cold, perturbative EOS of QCD of Fraga, Pisarski and Schaffner-Bielich is made. It is expected that our EOS can provide a possible new approach for the study of neutron stars.     

超强磁场对β衰变低能跃迁特征能级的影响

分析了超强磁场对非零温电子气体化学势的影响,研究了超强磁场下口衰变低能跃迁特征能级的变化情况,并以^59Fe,^62Co为例详细计算,结果表明,磁场B〈10^10T时,特征能级几乎不变,但是当达到超强磁场（B〉10^10T）时,特征能级明显降低．     

Realization of Spin Switch in a Triple-Terminal Double-Quantum-Dot Structure

Electron transport through a triple-terminal double-quantum-dot structure is theoretically studied. By adjusting the chemical potential in leads, two channels in this system are created, and in the presence of magnetic flux the conductances for the two channels present remarkable difference from each other. When the quantum dots are made of ferromagnetic materials, the levels of quantum dots are spin dependent, then spin polarization comes about in the two channels. Furthermore, in some regions spin polarization in the different channels are opposite. We consider that this model can be a device prototype for spin filtering and spin separation.     

标准平衡常数和平衡常数

本文从标准化学势的定义出发,导出各反应类型的标准平衡常数,并讨论了标准平衡常数K。和平衡常数K的区别和联系     

L—J流体化学势的分子模拟计算

用３ 种检测粒子法（Ｗｉｄｏｍ ,Ｋｕｍａｒ,ｆｇ ｓａｍｐｌｉｎｇ） 对Ｌ－Ｊ流体临界温度以上的数十个状态点的化学势进行了模拟计算。结果表明,这几种方法与由Ｌ－ Ｊ流体状态方程得出的值吻合很好,但其中Ｋｕｍａｒ 法的结果在有些状态点与其它方法相差较大。另外,即使在ρ＊ ≥１．０ 这样高的密度下,采用适当的技术处理后这几种方法都是可行的。     

物质标准态选择与平衡常数的关系

讨论了不同物质标准态的选择与各种平衡常数之间的关系。标准态不同,标准化学势不同,因而平衡常数不同。但标准态的选择不影响物质B的化学势μB值,也不影响化学反应的自由能变化△γGm值。本从各种物质标准态的选择出发,确立了物质在不同状态下化学势的表达式及不同反应体系中各种平衡常数的表达式,从而可清楚地了解μB、μB（T）、αB、K、Km、Kc、Kx、△γGm、△γGm等物理量间的相互关系。     

Linear Chemical Potential Dependence of Two-Quark Condensate

By differentiating the inverse dressed quark propagator at finite chemical potential μ with respect to μ, the linear response of the dressed quark propagato r to the chemical potential can be obtained, From this we extract a modelindependent formula for the linear chemical potential dependence of the in-medium two-quark condensate and show by two independent methods （explicit calculation and Lorentz covariance arguments） that the first-order contribution in μ to the in-medium two-quark condensate vanishes identically. Therefore if one wants to study the in-medium two-quark condensate one should expand to at/east the second order in the chemical potential μ.