Relative Nonsymmetry Effects of the Super(Generalized) Nonlinear Velocity, Time of a Particle and Its Kinetic Formulae for Followed Body

描述了粒子作高速运动时的超(广义)非线性速度、时间的相对不对称性效应和随体动力学诸公式。不对称性效应能解释次级宇宙线μ介子出现寿命延长的问题；也解释了著名的孪生子佯谬中谁年轻的争论问题。最后建立了随体的粒子动力学诸公式。     

用单位变化率定义和认识费雪效应公式

通过分析利用连续复利解释费雪效应公式中存在的问题,利用单位变化率概念给出了费雪效应关系新的表达式,并证明了所给公式与通常教材中的费雪效应公式等价.     

横观各向同性体滑移线场理论

本文系统推演了横观各向同性体滑移线场理论.为解决地球动力学与岩土力学问题,考虑到成层地质体横观各向同性与非均匀温度场作用,本文选择了Gol'denblat-Kopnov破坏准则.并使物性参数随温度变化,建立了复杂介质的强度准则.通过关联流动法则,导出了塑性流动基本方程.应用特征线理论,导出了滑移线斜率公式、应力沿滑移线微分公式和速度沿滑移线微分公式.应用本文理论计算了基础承压问题.本文理论将许多着名的经典理论如Mises理论,Hill理论、Coulomb理论概括为特例.这一综合理论可应用于岩土工程、地质构造、石油、采矿等许多领域.     

Blast Damage Simulation With the Discontinuous Galerkin Finite Element Method of Bond⁃Based Peridynamics北大核心CSCD

近场动力学是一种积分型非局部的连续介质力学理论,已广泛应用于固体材料和结构的非连续变形与破坏分析中,其数值求解方法主要采用无网格粒子类的显式动力学方法.近年来,弱形式近场动力学方程的非连续Galerkin有限元法得到发展,该方法不仅可以描述考察体的非局部作用效应和非连续变形特性,还可以充分利用有限单元法高效求解的特点,并继承了有限元法能直接施加局部边界条件的优点,可有效避免近场动力学的表面效应问题.该文阐述了键型近场动力学的非连续Galerkin有限元法的基本原理,导出了计算列式,给出了具体算法流程和细节,计算模拟了脆性玻璃板动态开裂分叉问题,并对爆炸冲击荷载作用下混凝土板的毁伤过程进行了计算分析.研究结果表明,该方法能够再现爆炸冲击荷载作用下结构的复杂破裂模式和毁伤破坏过程,且具有较高的计算效率,是模拟结构爆炸冲击毁伤效应的一种有效方法.     

电磁场中的电中性自旋1/2粒子及中子干涉

给出了电中性自旋1/2粒子在电磁场中的非相对论经典动力学,理论分析指出,穿过电磁场的非极化中子束量子位相干涉,只能被合理地解释为检测到自旋在外场中的进动,而不是量子物理中的“势效应”。即Aharonov-Casher和标势Aharnov-Bohm效应。     

斜纹夜蛾核型多角体病毒形态与结构

本文应用电子显微技术对斜纹夜蛾核型多角体病毒形态和精细结构进行了研究,病毒多角体在扫描电子显微镜下观察表面是皱褶不平的,多角体切片的蛋白质晶格与多角体经碱溶解后所见块状蛋白质晶格相同,其晶格间距约为20埃,多角体蛋白质晶格的亚单位呈六角形,病毒粒子在病毒束内呈不对称性排列,数目不恒定,病毒粒子的螺旋结构为13—15螺转,螺距约为150埃。     

投资者情绪的不对称性及其原因——来自中国市场的实证

文章首先验证了隔夜收益率可以作为中国股票市场中衡量个股日度投资者情绪的指标.使用这一指标,文章实证发现在中国市场上正向情绪和负向情绪具有不对称性:正向情绪的短期持续性小于负向情绪的短期持续性,负向情绪相较正向情绪需要更长的时间来释放.这一现象可由中国市场上个人投资者的处置效应解释.研究发现投资者情绪的不对称性在个人投资者占比高的股票上表现得更为强烈,而且正向投资者情绪相较负向投资者情绪驱动着更高的市场交易.     

强磁场中无自旋和自旋粒子的Synchro-Curvature辐射谱

Synchro-Curvature辐射是张家铝和郑广生最近提出的一种新的、更普遍的辐射机制,它全面描述了一个相对论性带电粒子在弯曲磁场中运动时所产生的辐射特征.这种新辐射机制概括了通常同步辐射及曲率辐射的全部经典结果,揭示了其间的有机联系和统一性.并为精确讨论脉冲星研究中的辐射问题给出了普遍而简单的统一公式.不过由于脉冲星磁场已高达10⁸T,量子效应不能不考虑,应用最近Lieu和Axford发展的GFWW方法推广了张家铝和郑广生的结果,对无自旋的K-G粒子及有自旋的Dirac粒子给出了其相应的Synchro-Curvature量子辐射谱公式,并讨论了它们的辐射特性.     

不变的赋值函数与Cauchy投影公式(英文)

本文研究了Rn中凸集上不变的赋值函数与凸体的投影问题.利用赋值函数的方法,我们获得了凸体在任意维平面上投影的Cauchy公式和Kubota公式,这些结果推广了经典的Cauchy公式和Kubota公式.     

相对论裸粒子Green函数和碰撞积分

从相对论非平衡态统计系综理论出发,利用Bogoliubov假设和极化近似,用裸粒子Green函数方法求解相对论两体关联方程,导出用裸粒子Green函数表示的相对论动力方程碰撞积分的一般公式,导出适用于相对论等离子体的的“广义Boltzmann方程”.     

Numerical modeling of the movement of a rigid particle in viscous fluid

Modeling the movement of a rigid particle in viscous fluid is a problem physicists and smathematicians have tried to solve since the beginning of this century. A general model for an ellipsoidal particle was first published by Jeffery in the twenties. We exploit the fact that Jeffery was concerned with formulae which can be used to compute numerically the velocity field in the neighborhood of the particle during his derivation of equations of motion of the particle. This is our principal contribution to the subject. After a thorough check of Jeffery's formulae, we coded software for modeling the flow around a rigid particle based on these equations. Examples of its applications are given in conclusion. A practical example is concerned with the simulation of sigmoidal inclusion trails in porphyroblast.     

The motion of a particle in a viscous fluid under gravity,vibration and Basset's force

The sedimentation of a heavy solid spherical particle from a state of rest in an incompressible viscous fluid in a vessel with a vibrating bottom is investigated. Taking the Basset force into account, the problem is reduced to solving a Cauchy problem for a linear integro-differential equation. An exact solution of this problem and simple asymptotic formulae are obtained and a complete analysis of the effect of the Basset force on the oscillations and sedimentation of the particles is carried out. It is shown that a consideration of the Basset force introduces a considerable correction to the classical amplitude-frequency relation, reducing its value and also considerably slowing the arrival of the amplitude at a constant value. When there are no vibrations, it follows from the solution of the problem that there is a slow establishment of the limiting velocity (inversely proportional to the square root of the time), which differs considerably from the case of the sedimentation of particles in accordance with Stokes's law (the establishment of the limiting velocity occurs exponentially).     

速度空间的D'Alembert原理

从质点系的牛顿动力学方程出发,考虑力是坐标ｒ 、速度⒒ｒ 和时间ｔ 的函数的情况,引入速度空间的“动能”（ 即加速度能） 的概念,导出了完整系和非完整系速度空间的 Ｄ’ Ａｌｅｍｂｅｒｔ 原理的各种形式·     

Pulsatile flow of particle-fluid suspension model of blood under periodic body acceleration

A particle-fluid suspension model is applied to the problem of pulsatile blood flow through a circular tube under the influence of body acceleration. With the help of finite Hankel and Laplace transforms, analytic expressions for axial velocity for both fluid and particle phase, fluid acceleration, wall shear stress and instantaneous flow rate have been obtained. It is observed that the solutions can be used for all feasible values of pulsatile and body acceleration Reynolds numbers R_p and R_b. Using physiological data, the following qualitative and quantitative results have been obtained. The amplitude Q_b of instantaneous flow rate due to body acceleration decreases as the tube radius decreases. The effect of the volume fraction of particle C on Q_b is to increase it with increase of C in arteriole and to decrease Q_b as C increases in coronary and femoral arteries. The maximum of the axial velocity and fluid acceleration shifts from the axis of the tube to the vicinity of the tube wall as the tube diameter increases. The effect of C on the velocity and acceleration are nonuniform. The wall shear amplitude t_b\tau_b due to body acceleration increases as the tube diameter decreases from femoral to coronary and a further decrease in the tube diameter leads to a decrease in t_b\tau_b. The effects of C on t_b\tau_b are again nonuniform.     

Evaluation of reduction behavior of blast furnace dust particles during in-flight process with experiment aided mathematical modeling

In-flight reduction technology is a flexible process that allows recycling of the fine iron bearing metallurgical dusts efficiently. In this work, a mathematical model, incorporating introduced experimental kinetic parameters, was developed to accurately evaluate the reduction behavior of blast furnace (BF) dust particles during flight. A detailed evaluation of particle residence time, thermal history and reduction degree conversion were used to eliminate the deviations related to the assumptions of constant particle velocity and temperature in the experiment. The results show that the particle velocity decreases along the longitudinal direction of the reactor for a long distance and reaches a constant low velocity at the middle part of the reaction zone. The calculated particle residence time is 0.15–0.44 s less than the experimentally estimated value. The particle temperature reaches the isothermal temperature at the 0.15 m position from the reaction zone bottom. An obvious transition of reduction degree of dust particle is found when particle temperature reaches over 1640 K. The prediction accuracy of the model was improved by using the optimized kinetic parameters, namely pre-exponential factor and activation energy.     

The radial basis reproducing kernel particle method for geometrically nonlinear problem of functionally graded materials

In this paper, the radial basis function (RBF) is introduced into the reproducing kernel particle method (RKPM), and the radial basis reproducing kernel particle method (RRKPM) is proposed for solving geometrically nonlinear problem of functionally graded materials (FGM). Compared with the RKPM, the advantages of the proposed method are that it can eliminate the negative effect of different kernel functions on the computational accuracy, and has higher computational accuracy and stability. Using the Total Lagrange (T.L.) formulation and the weak form of Galerkin integration, the corresponding formulae for geometrically nonlinear problem of FGM are derived. The penalty factor, shaped parameter of the RBF, the control parameter of influence domain radius, loading step number and node distribution are discussed. Furthermore, the effects of different gradient functions and exponents on displacement and stress are analyzed. Newton-Raphson (N-R) iterative method is utilized for numerical solution. The proposed method is correct and effective for solving geometrically nonlinear problem of FGM, which can be demonstrated by several numerical examples.     

Strong Propagations of Chaos in Moran's Type Particle Interpretations of Feynman–Kac Measures

Abstract

This article is concerned with strong propagations of chaos properties in Moran's type particle interpretations of continuous time Feynman–Kac formulae. These particle schemes can also be seen as approximating models of simple generalized spatially homogeneous Boltzmann equations. We provide a simple and original semigroup analysis based on empirical tensor measures combinatorics properties, martingales techniques, and coupling arguments. We also design a general and abstract framework without any topological assumption on the state space. This yields a natural way to analyze the propagations of chaos properties for interacting particle models on path space. Applications to genealogical type particle algorithms for the nonlinear filtering and smoothing problem are also discussed.     

极限分析的广义界限定理

本文研究了非连续流动场中,刚塑性介质极限分析完全解的界限问题.提出了一个包括界面条件及间断面条件在内的混合边值问题的广义变分原理,建立了极限载荷乘子的变分解析公式.并证明了一个新的界限定理,其中的场变量将不再受到屈服条件、不可压缩条件等约束的限制.此定理的推论给出了变分解与完全解之间的关系.初步应用表明,对于简单选取的场变量,由本文公式可以得到准确解的较佳界限值,结果具有较好的稳定性.     

Analysis of models for calculating the motion of solids of revolution of minimum resistance in soil media

The solution of problems of searching for the optimal shape of a body when it penetrates into dense media is considered using local interaction models (LIMs) and Grigoryan's model of a soil medium in an axisymmetric formulation. A new LIM is obtained that is improved by taking account of the non-linear compressibility and shear strength in the analytical solution of a problem on the expansion of a spherical cavity. The applicability of an LIM that is quadratic with respect to the velocity in determining the forces resisting penetration of sharp bodies into soft soil is justified theoretically and experimentally and the violation of the conditions for the model to be applicable in the case of blunt bodies is established. It is shown that a solution taking account of non-linear flow effects in a two-dimensional formulation enables both the shape as well as power and kinematic characteristics of the optimal blunt bodies as they pass through soil media to be improved considerably. The ratio of the finite depths of penetration of solids of revolution into soft ground taking account of internal friction is estimated by the ratio of the coefficients in the Rankine–Resal formulae.     

Optimal estimation of Eulerian velocity field given Lagrangian observations

The problem of estimating an Eulerian velocity field given particle trajectories is formulated as an optimal filtering problem. Under the idealistic assumption that the Eulerian velocity field is delta-correlated in time (Kraichnan model) the exact solution of the non-linear filtering problem is found. In a more realistic Markov model with finite correlation time an approximate solution is suggested and examined by Monte Carlo means.