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81.
Robert Ehrlich 《Physics in Perspective (PIP)》2006,8(1):83-89
I compare the theory of intelligent design to string theory to see on what basis, if any, only the former can be justifiably
excluded as being scientific.We shall see that the classic criterion of testability or falsifiability is sometimes not so
straightforward, and that there are other criteria to help us make such a distinction. 相似文献
82.
According to the basic idea of classical yin-yang complementarity and modern dual-complementarity, in a simple and unified
new way proposed by Luo, the unconventional Hamilton-type variational principles for electromagnetic elastodynamics can be
established systematically. This new variational principles can fully characterize the initial-boundary-value problem of this
dynamics. In this paper, the expression of the generalized principle of virtual work for electromagnetic dynamics is given.
Based on this equation, it is possible not only to obtain the principle of virtual work in electromagnetic dynamics, but also
to derive systematically the complementary functionals for eleven-field, nine-field and six-field unconventional Hamilton-type
variational principles for electromagnetic elastodynamics, and the potential energy functionals for four-field and three-field
ones by the generalized Legendre transformation given in this paper. Furthermore, with this approach, the intrinsic relationship
among various principles can be explained clearly. 相似文献
83.
84.
关于由衍射片的背面反射光形成的衍射图样的讨论 总被引:1,自引:0,他引:1
在光的衍射实验中,我们看到的一般是由通过衍射片的直射光形成的衍射图样,但在衍射片的另一面,同样存在着另一个衍射图样,它是由衍射片的背面反射光形成的,两个衍射图样关于衍射片对称.本文给出了这种实验现象,并用巴比涅原理解释了这种现象. 相似文献
85.
ZHAO Ren ZHANG Li-Chun HU Shuang-Qi 《理论物理通讯》2006,46(4):635-638
We generalize the method that is used to study corrections to Cardy-Verlinde formula due to generalized uncertainty principle and discuss corrections to Cardy-Verlinde formula due to generalized uncertainty principle in (anti)- de Sitter space. Because in de Sitter black hole spacetime the radiation temperature of the black hole horizon is different from the one of the cosmological horizon, this spacetime is a thermodynamical non-equilibrium spacetime. 相似文献
86.
LUO En & LI WeiHua Department of Applied Mechanics Engineering Sun Yat-sen University Guangzhou China 《中国科学G辑(英文版)》2007,50(3):370-378
According to the basic idea of classical yin-yang complementarity and modern dual-complementarity, in a simple and unified way proposed by Luo, some basic principles in the dynamic theory of viscoelastic materials with voids can be estab- lished systematically. In this paper, an important integral relation in terms of con- volutions is given, which can be considered as the generalized principle of virtual work in mechanics. Based on this relation, it is possible not only to obtain the principle of virtual work and the reciprocal theorem, but also to derive systemati- cally the complementary functionals for the eight-field, six-field, four-field simpli- fied Gurtin-type variational principles and the potential energy-functional for the two-field one in the dynamic theory of viscoelastic materials with voids by the generalized Legendre transformations given in this paper. Furthermore, with this approach, the intrinsic relationship among various principles can be explained clearly. 相似文献
87.
From first principle calculations, we demonstrate that LiXS_2(X = Ga, In) compounds have potential applications as cathode materials for Li ion batteries. It is shown that Li can be extracted from the LiXS_2 lattice with relatively small volume change and the XS_4 tetrahedron structure framework remains stable upon delithiation. The theoretical capacity and average intercalation potential of the LiGaS_2(LiInS_2) cathode are 190.4(144._2) m Ah/g and 3.50 V(3.53 V). The electronic structures of the LiXS_2 are insulating with band gaps of _2.88 eV and 1.99 eV for X = Ga and In, respectively.However, Li vacancies, which are formed through delithiation, change the electronic structure substantially from insulating to metallic structure, indicating that the electrical conductivities of the LiXS_2 compounds should be good during cycling.Li ion migration energy barriers are also calculated, and the results show that Li ion diffusions in the LiXS_2 compounds can be as good as those in the currently widely used electrode materials. 相似文献
88.
The aim of this paper is to show that the procedure of maximum entropy principle for the closure of the moments equations for rarefied monatomic gases can be extended also to polyatomic gases. The main difference with respect to the usual procedure is the existence of two hierarchies of macroscopic equations for moments of suitable distribution function, in which the internal energy of a molecule is taken into account. The field equations for 14 moments of the distribution function, which include dynamic pressure, are derived. The entropy and the entropy flux are shown to be a generalization of the ones for classical Grad’s distribution. The results are in perfect agreement with the recent macroscopic approach of extended thermodynamics for real gases. 相似文献
89.
以脱氧核糖核酸和工程中的细长结构为背景, 大变形大范围运动的弹性杆动力学受到关注. 将分析力学方法运用到精确Cosserat弹性杆动力学, 旨在为前者拓展新的应用领域, 为后者提供新的研究方法. 基于平面截面假定, 在弯扭基础上再计及拉压和剪切变形形成精确Cosserat弹性杆模型. 用刚体运动的概念描述弹性杆的变形, 导出弹性杆变形和运动的几何关系; 在定义截面虚位移及其变分法则的基础上, 建立用矢量表达的d’Alembert-Lagrange原理, 在线性本构关系下化作分析力学形式, 并导出Lagrange方程和Nielsen方程, 定义正则变量后化作Hamilton正则方程; 对于只在端部受力的弹性杆静力学, 导出了将守恒量预先嵌入的Lagrange方程, 并讨论了其首次积分. 从弹性杆的d’Alembert-Lagrange原理导出积分变分原理, 在线性本构关系下化作Hamilton原理. 形成的分析力学方法使弹性杆的全部动力学方程具有统一的形式, 为弹性杆动力学的对称性和守恒量的研究及其数值计算铺平道路.
关键词:
精确Cosserat弹性杆
分析动力学方法
变分原理
Lagrange方程 相似文献
90.
为研究清凉寺窑汝瓷胎和张公巷窑青瓷胎的原料特征及来源, 选取37个清凉寺窑汝瓷胎样品(32个汝官瓷胎和5个汝民瓷胎)、 32个张公巷窑青瓷胎样品以及14个岩石样品, 用中子活化分析 (NAA)方法测得每个样品中的23种元素含量; 使用散布分析及主成分分析方法处理NAA数据。 结果表明: 元素Fe, Ce, Ba, Ta, Th, La, Sm和Cr可作为区分汝官瓷胎和张公巷窑青瓷胎原料产地的指纹元素; 汝官瓷胎原料产地较集中, 来源相对稳定; 清凉寺窑汝民瓷胎料产地与汝官瓷基本相同, 均为就地取材; 张公巷窑青瓷胎原料产地较为分散, 与汝官瓷不同, 但二者距离相近。 关 相似文献