Reversibility and irreversibility from an initial value formulation

From a time evolution equation for the single particle distribution function derived from the N-particle distribution function (A. Muriel, M. Dresden, Physica D 101 (1997) 297), an exact solution for the 3D Navier–Stokes equation – an old problem – has been found (A. Muriel, Results Phys. 1 (2011) 2). In this Letter, a second exact conclusion from the above-mentioned work is presented. We analyze the time symmetry properties of a formal, exact solution for the single-particle distribution function contracted from the many-body Liouville equation. This analysis must be done because group theoretic results on time reversal symmetry of the full Liouville equation (E.C.G. Sudarshan, N. Mukunda, Classical Mechanics: A Modern Perspective, Wiley, 1974). no longer applies automatically to the single particle distribution function contracted from the formal solution of the N-body Liouville equation. We find the following result: if the initial momentum distribution is even in the momentum, the single particle distribution is reversible. If there is any asymmetry in the initial momentum distribution, no matter how small, the system is irreversible.     

本科生量子信息教学几点体会

量子信息的概念和原理相当抽象,为了使学生更容易理解量子信息的基本概念和原理,在教学中提供一些通俗易懂的例题,将量子信息概念和原理通过实例具体化,这对学生深刻领会量子信息基本概念和原理有很大帮助,并取得了较好的教学效果.     

基于狭义相对论的同时性对长度收缩佯谬的认识

利用狭义相对论对同时性的理解,指出了关于一种长度收缩佯谬解释的不妥之处,并解释了改进后的关于长度收缩佯谬的提法,证明了在不同参照系上的观测者观测所得到的结论相同.     

零售商主导型供应链渠道管理与悖论机制分析

普遍认为零售企业压榨供应商、但实际上供应商利润率远高于零售商是业界关注的一个热点商业悖论问题。通过构建无退货、一般退货、全额退货、线性回扣等体现零售商不同强势地位的供应链渠道管理模型,研究并比较了退货和回扣等强势契约机制以及销售努力对零售供应链管理绩效的影响。分析表明供应商通过批发价定价可以有效转移强势契约带来的风险和成本支付,零售商不能通过强势契约显著提升零售供应链效益。零售商应该利用渠道优势首先强化对批发价定价权的影响,在此基础上合理采用强势契约机制。本文研究很好地解释了零供双方渠道地位与利润水平矛盾的商业悖论问题。     

THEORETICAL ANALYSIS AND EXPERIMETNAL VERIFICATION FOR PAINLEV碋 PARADOX

含摩擦的多体系统可能存在Painlevé 疑难奇异性-- 多体系统的后续运动可能存在无解(非协调状态)或者多解(不确定状态). 实际系统总要运动下去, 而对应于非协调奇异性状态的多体系统将经历怎样的运动值得探讨. 从计算、实验和理论证明3 个角度研究Painlevé 疑难问题, 验证和证明了多体系统处于非协调状态时其后续运动的切向冲击特征, 并揭示了切向冲击运动的共同规律.     

Implications of Local Friendliness Violation for Quantum Causality

We provide a new formulation of the Local Friendliness no-go theorem of Bong et al. [Nat. Phys. 16, 1199 (2020)] from fundamental causal principles, providing another perspective on how it puts strictly stronger bounds on quantum reality than Bell’s theorem. In particular, quantum causal models have been proposed as a way to maintain a peaceful coexistence between quantum mechanics and relativistic causality while respecting Leibniz’s methodological principle. This works for Bell’s theorem but does not work for the Local Friendliness no-go theorem, which considers an extended Wigner’s Friend scenario. More radical conceptual renewal is required; we suggest that cleaving to Leibniz’s principle requires extending relativity to events themselves.     

圆柱型正交各向异性弹性楔的佯谬解

圆柱型正交各向异性弹性楔体顶端受有集中力偶的经典解,当顶角满足一定关系时,其应力成为无穷大,这是个佯谬．该文在哈密顿体系下将该问题进行重新求解,即利用极坐标各向异性弹性力学哈密顿体系．在原变量和其对偶变量组成的辛几何空间求解特殊本征值的约当型本征解,从而直接给出该佯谬问题的解析解．结果再次表明经典力学中的弹性楔佯谬解对应的是哈密顿体系下辛几何的约当型解．     

直角杠杆佯谬的能流解释和弹性定律协变性的统一

直角杠杆佯谬是指可绕角顶自由转动的直角杠杆在一个惯性系中已达力学平衡,但变换到另一惯性系中出现力矩,却仍处于平衡状态的似有矛盾的问题．本文介绍了劳厄的能流解释,并将其与弹性定律的协变性解释统一起来     

Fast incremental algorithm for speeding up the computation of binarization

Binarization is an important basic operation in image processing community. Based on the thresholded value, the gray image can be segmented into a binary image, usually consisting of background and foreground. Given the histogram of input gray image, based on minimizing the within-variance (or maximizing the between-variance), the Otsu method can obtain a satisfactory binary image. In this paper, we first transfer the within-variance criterion into a new mathematical formulation, which is very suitable to be implemented in a fast incremental way, and it leads to the same thresholded value. Following our proposed incremental computation scheme, an efficient heap- and quantization-based (HQ-based) data structure is presented to realize its implementation. Under eight real gray images, experimental results show that our proposed HQ-based incremental algorithm for binarization has 36% execution-time improvement ratio in average when compared to the Otsu method. Besides this significant speedup, our proposed HQ-based incremental algorithm can also be applied to speed up the Kittler and Illingworth method for binarization.