Level Spacing Distributions and Quantum Chaos in Hermitian and non-Hermitian Systems

The correspondence between quantum level spacing distributions and classical motion of 1-D PT symmetric non-Hermitian systems is investigated using two PT symmetric complex potentials- complex rational power potential V1(x) = (ix)^(2n 1)/m and genera/polynomial potential V2(x) =x^2M ib1x^2M-1 b2x^2M-2 … ib2M-1x. The level spacing distribution of V1 has two forms. When 2n 1-2m is positive, the level spacing distribution of real eigen values assumes a decreasing power function, while it behaves as an increasing power function when 2n 1-2m is negative.The PT symmetry of this system is spontaneously broken as 2n 1 - 2m becomes negative. This change manifests itself in classical mechanics as it is found by Bender et al. However, it was found that the change in the form of level spacing distribution mentioned above is not due to the spontaneous breaking down of PT symmetry. Level spacing distribution of V2 assumes an increasing power function when order of the polynomial is greater than two.     

密等离子体Ni-like金离子双电子复合的理论研究

以碰撞-辐射模型为基础,推导了含电子密度修正的双电子复合速率系数计算公式.以类镍金离子为例,计算并讨论了密等离子体中辐射衰变发生在3d-5f的总双电子复合速率系数.     

A SHIFT-SPLITTING PRECONDITIONER FOR NON-HERMITIAN POSITIVE DEFINITE MATRICES

A shift splitting concept is introduced and, correspondingly, a shift-splitting iteration scheme and a shift-splitting preconditioner are presented, for solving the large sparse system of linear equations of which the coefficient matrix is an ill-conditioned non-Hermitian positive definite matrix. The convergence property of the shift-splitting iteration method and the eigenvalue distribution of the shift-splitting preconditioned matrix are discussed in depth, and the best possible choice of the shift is investigated in detail. Numerical computations show that the shift-splitting preconditioner can induce accurate, robust and effective preconditioned Krylov subspace iteration methods for solving the large sparse non-Hermitian positive definite systems of linear equations.     

多答案保护秘密共享协议

针对目前基于口令解决区块链私钥丢失问题的方案中面临的口令遗忘和泄露的问题,提出一种基于密保问题的多答案保护秘密共享方案（multi-answer protected secret sharing,MAPSS）。该方案允许用户将一个秘密共享给多个服务器,并令所有服务器存储多个密保问题,之后用户仅需向部分（阈值）服务器提供部分（阈值）密保问题的答案就能重构该秘密。该方案不仅可以用于区块链私钥找回,还支持抗遗忘和泄露的找回策略;该方案无需公钥基础设施且高效。在随机预言机模型下证明了该方案的安全性基于Threshold Parallel One-More Diffie-Hellman (TP-OMDH)假设,实现了该方案的系统原型,验证了该方案的实用性。     

He-O_2转动激发截面的理论计算

用公认精确的密耦 (Close Coupling)方法、采用两种不同的相互作用势计算了He -O2 碰撞的态 态转动激发截面 (E =2 6.8meV) ,通过系统研究和计算发现 :低能散射时 ,He -O2 碰撞的弹性散射主要发生在小角部分 ,而非弹性转动激发主要发生在大角部分。研究表明 :转动激发截面对势能表面的方向性和散射角都非常敏感。     

食用天然色素密蒙黄稳定性分析研究

研究了食品中常见的几种金属离子Na^ 、Cu^2 、Al^3 、Fe^3 、Sn^2 和维生素C、苯甲酸等食品添加剂对食用天色色素密蒙黄稳定性的影响,并对色素的耐碱性和耐热性进行了探讨,结果表明其性能稳定。本研究为密蒙黄色素的开发应用提供了依据。     

赵忠尧,电子对产生和湮灭

 作为20世纪物理学发展的里程碑,关于电子无穷海的狄拉克理论现在已被普遍认为是粒子物理基础的不可分割的一部分.然而它曾有过一段难以被人们接受的时期.     

Low-temperature specific heat and resistance for the heavy-electron metals CeCu6-xMx （M=Ni,Zn）

The specific heat and resistance of CeCu_{6-x}M_x (M=Ni,Zn) have been studied in the concentration range where they still retain the orthorhombic structure. The coefficient c of -ln T term in resistance R=R_0+bT-cln T, as well as the γ, have been found to vary in opposite directions with increasing x for Ni and Zn substitutions. The physical mechanism is discussed.     

六角密堆结构的Mbius变换及镁的对势

提出并证明了一个适用于六角密堆(hcp)结构的Mbius变换公式.从晶体中原子的结合能出发，利用这个公式可以得到具有hcp结构的晶体中原子间的相互作用对势.作为例子，利用这一方法计算了镁的对势. 关键词：