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61.
The plastic deformation mechanism operating in polymer glasses is analyzed. The whole process consists of two main stages: nucleation of special shear defects, called PSTs (plastic shear transformations), and their disappearance. The important feature of plastic deformation of glasses is the storage of a large amount of internal energy ΔUdef upon straining. Such energy storage is the critical issue for mechanical performance of polymeric material: if the amount of stored energy is high, the appearance of macroscopic failure is very probable while glassy materials collecting a small amount of stored deformation energy are quite ductile. It is proposed that the rate of disappearance of PSTs is a key factor in dissipation of stored deformation energy. A parameter describing the dissipation ability of material upon deformation is introduced. 相似文献
62.
考虑横向变形的薄壁箱梁计算 总被引:1,自引:0,他引:1
殷治宁 《合肥工业大学学报(自然科学版)》1998,(5)
在符拉索夫的虚功法的理论基础上,对符氏虚功方程进行扩充,讨论多箱带悬壁的薄壁箱梁在截面横向可变形及悬臂转动情况下,截面纵向、横向位移和应力计算方法。通过算例,分析虚功方程的计算结果。 相似文献
63.
方丽萍 《北京理工大学学报》1998,18(1):1-4
研究整函数族fλ(z)=ze^z+λ(λ∈C)的动力系统。方法用Baker研究e^λz所采用的方法。结果与结论设Dp={λ∈| fλ(z)有一个p阶的吸性周期点},Dp表示Dp的一个连通分支。 相似文献
64.
整(0,m)插值的推广 总被引:2,自引:0,他引:2
王梅英 《北京师范大学学报(自然科学版)》1998,34(3):313-318
引进了一类新的指数型整函数插值,推广了(0,m)插值,同时也考虑了该插值算子的收敛性。 相似文献
65.
房艮孙 《北京师范大学学报(自然科学版)》1998,34(2):156-161
证明了S2m(T,R)∩L2(R)上的Marcinkiewicz-Zygmund型不等式及Bernstein型不等式,其中S2m(T,R)是以{tj}为非正规节点系的缓增的2m阶多项式样条函数空间,节点系{tj}满足Kadets1/4定理的条件,即tj=j+wj,sup↓j│wj│≤r〈1/4,wj∈R,j∈Z,由以上结果,进一步给出了在节点系上插值的插值样条s2mf(x)在L2(R)中收敛到f( 相似文献
66.
CSCW多媒体同步与协同模型 总被引:2,自引:0,他引:2
介绍了CSCW和群件基本概念,讨论了CSCW和群件的关键技术和发展现状,提出了一种基于多媒体同步关系的面向群件的多媒体同步协同模型,并讨论了初步实现技术和方案。 相似文献
67.
Thermal plasma processing involves complex interactions of particulates with plasmas. In previous studies (see Parts I and II of this series), an assessment of different effects has been made considering the dynamics and heat and mass transfer of a single particle immersed into a thermal plasma. The last paper of this sequence is concerned with the simulation of thermal plasma jet reactors and the effects caused by multiparticle injection.A mathematical model is proposed for the simulation of thermal plasma jet reactors, including the mixing phenomena between the jet and the surrounding gases by generalizing the governing equations for simple mixing flows. Also included is the density fluctuation effect by extending the K- model to a four-equation turbulence model combined with a probability density function. This model is internally consistent covering additional physical phenomena which are not covered by existing models. Unfortunately, its expected higher accuracy cannot be proven because of the present uncertainties associated with the input.For multiparticle injection, the simulation repeats calculations for single-particle injection, but with different initial conditions correcting the solutions by considering the coupling effects between particles and the plasma.The results indicate that (i) thermal plasmas show different mixing behavior in different gases; (ii) the density fluctuation effect is important since it causes large differences between the mass-weighted and unweighted time-averaged temperatures of thermal plasma jets; (iii) coupling effects become important when the particle loading rate exceeds half of the plasma mass flow rate; (iv) there are 16 constraints imposed on the modeling work which have to be considered for establishing a base for comparison with future experimental studies. 相似文献
68.
69.
E.B. Lobkovskii G.L. Soloveichik A.I. Sisov B.M. Bulychev A.I. Gusev N.I. Kirillova 《Journal of organometallic chemistry》1984,265(2):167-173
The structure of a titanium aluminium hydride complex of composition [(C5H5)2TiAlH4]2(CH3)2NC2H4N(CH3)2C6H6 has been determined by X-ray diffraction. The complex forms triclinic crystals with unit cell dimensions a = 8.406(2), b = 10.117(2), c = 11.269(3) Å; α = 112.01(2)°, β = 109.25(2)°, γ = 87.04(2)°, space group P, Z = 2 and density d = 1.21 g/cm3. The structure was refined to give a discrepancy index R = 0.056. The crystals are composed of centrosymmetric molecules of (Cp2TiAlH4)2TMEDA (Cp = η5-cyclopentadienyl) and molecules of crystal benzene. Two moieties of Cp2TiH2AlH2 are linked by a tetramethylethylenediamine molecule (rAlN 2.11 Å). The aluminium atom is bonded to a titanium atom by a double hydride bridge (rAlH b = 1.8, 1.6 Å, rTiH b = 1.6 Å), and has trigonal bipyramidal stereochemistry, [H4N] (rAlH t = 1.6 Å). 相似文献
70.
Brian J. Brisdon 《Journal of organometallic chemistry》1977,125(2):225-230
Compounds of the type [XM(CO)2(ν-allyl)L2] (where X = Cl and Br; M = Mo and W; L2 = Ph2PCH2PPh2 and Ph2 PCH2CH2PPh2) have been prepard from the corersponding MeCN complexes. The spectral properties of these compounds and the effects of chelate rign size on 31P coordination shifts and J(183W—31P) have been investigated. 相似文献