A THREE-DIMENSIONAL ELASTICITY SOLUTION FOR TWO-DIRECTIONAL FGM ANNULAR PLATES WITH NON-UNIFORM ELASTIC FOUNDATIONS SUBJECTED TO NORMAL AND SHEAR TRACTIONS

In the present paper, bending and stress analyses of two-directional functionally graded （FG） annular plates resting on non-uniform two-parameter Winkler-Pasternak founda- tions and subjected to normal and in-plane-shear tractions is investigated using the exact three- dimensional theory of elasticity. Neither the in-plane shear loading nor the influence of the two- directional material heterogeneity has been investigated by the researchers before. The solution is obtained by employing the state space and differential quadrature methods. The material proper- ties are assumed to vary in both transverse and radial directions. Three different types of variations of the stiffness of the foundation are considered in the radial direction： linear, parabolic, and sinu- soidal. The convergence analysis and the comparative studies demonstrate the high accuracy and high convergence rate of the present approach. A parametric study consisting of evaluating effects of different parameters （e.g., exponents of the material properties laws, the thickness to radius ratio, trends of variations of the foundation stiffness, and different edge conditions） is carried out. The results are reported for the first time and are discussed in detail.     

Electrical and Optical Properties of Conducting TCNQ Salts

New series of TCNQ molecular complexes and organic radical-lm salts are presented. Their electrical behavior is related to their optical properties: characteristic parameters, such as the plasma frequency and the relaxation time. arc dcduced.     

Isoprene Polymerization by Butyllithium in Cyclohexane. I. Initiation Reaction

Kinetic studies, using a gas chromatographic method, of the consumption of n-, sec-, and t-butyllithium during the polymerization of isoprene in cyclohexane show in the three cases a sigmoidal curve. When the concentration of polyisoprenyllithium increases, the initiation rate goes through a maximum with n-butyllithium but continuously increases in the two other cases. The three corresponding lithium-butoxides have a drastic effect on the initiation rate. Thus, the addition of n-butoxide strongly increases the initial rate, but the rate further decreases except in the case of sec-butyl-lithium. The behavior of the sec-butoxide is roughly the same, but more limited, while the t-butoxide causes a slight initial promotion in the case of n-BuLi and sec-BuLi but decreases the initiation rate in the case of t-BuLi. These results are discussed in terms of association of organolithium molecules and ion pairs reactivity.     

An Introduction to the Solid State Polymerization of Transition-metal Complexes: A Comparative Study

Preliminary studies in this laboratory^' of topochemical and topotactic polyreactions of NiBr₂[P(CH₂CH₂CN)₃]₂ have shown that the reactions are in many cases characterized by a) product specificity, b) stereospecificity, c) “crystallographic specificity” and d) highly anisotropic “front motion” through individual single crystals. The polymerization reaction under investigation here is     

Some basic problems in numerically simulating effective properties and local fields of composite materials

It is pointed out that to numerically estimate the effective properties and local fields of matrix-inclusion composites, a commonly adopted method is accompanied with some serious draw-backs. We call this method the nominal loading scheme (NLS), which considers the actual inclusion distribution inside a finite domain, Ω say, treats the external domain of Ω to be of the pure matrix material, and imposes the actural traction, σ^∞ say on the remote boundary. It thus gives rise to the following basic problems: (i) Can NLS be improved remarkably just by adjusting σ^∞? (ii) What is the relationship between the size of Ω and the scale of inclusions? (iii) Which choice is better in calculating the effective properties, the whole domain Ω or an appropriately selected sub-domain of Ω? Targeting these problems, the equivalent loading scheme (ELS) and equivalent matrix scheme (EMS) are proposed. It is theoretically analyzed that both ELS and EMS can be used to precisely simulating the effective properties and local fields of matrix-inclusion composities, and both ELS and EMS are self-approved. As an application, ELS combined with a so-called pseudo-dislocations method is used to evaluate the effective properties and local fields of two-dimensional two-phase composites with close-packed circular inclusions, or randomly distributed circular inclusions, or randomly distributed microcracks. The results show that substituting the remore traction σ^∞ with the effective stress field σ^ɛ suggested by IDD scheme is a simple and effective method, and the estimation of the effective properties and local fields is very close to the accurate solution. The present work is supported by the National Natural Science Foundation of China (No. 19525207).     

关于有信用风险的期权定价的鞅方法

本文考虑了一个关于具有对方风险的衍生物的金融模型\bd 应用公司价值模型, 本文讨论了关于具有对方破产风险的衍生物的欧式期权定价问题\bd 应用鞅方法, 在高斯分布等的假设下本文得到并证明一个关于该期权的显式Black-Scholes定价公式\bd 该公式推广了Ammann在[1]中的相应结果.     

一个推广的Hilbert型不等式及其等价式

引入单参量λ及估算权系数,建立一个新的具有混合核的Hilbert型不等式以最佳常数因子的推广.作为应用,给出了其等价形式及一些特殊结果.     

Molecular dynamics simulations of thermodynamics,elastic constants and solid solution strengths for Mg-Gd alloys

The thermal and mechanical properties of Mg-Gd intermetallics MgGd, MgGd₂ and MgGd₃ are studied using a modified analytical embedded atom method. Calculated results agree well with the available experimental data and other theoretical results. The results on the elastic constants suggest that thermal softening behavior is observed as the temperature increases and the bulk moduli of ordered phases are larger than that of elemental Mg above 300 K. The heat capacities of MgGd, Mg₂Gd and Mg₃Gd are 22.91, 23.04 and 23.09 J mol K^-1, respectively, at 300 K. Furthermore, the addition of Gd gives rise to an increase of c/a. With the same content of Gd, the ratio c/a remains unchanged with increasing temperature, whereas this phenomenon does not occur in pure Mg, which indicates that the temperature-independent c/a restrains the occurrence of non-basal slip and twinning. Hence the addition of Gd can enhance the strength of Mg, in good agreement with experimental observation.     

Analysis of Wet Pressing of Paper: The Three-Phase Model. Part II: Compressible Air Case

In this study we consider a model of wet pressing of paper. We use the techniques and results from the first part of this paper, where a simplified model is studied in details. The model is, using suitable transformation, rewritten in the standard parabolic-hyperbolic form. Numerical solution for typical example is given and the effects of plastic deformations of paper are investigated. Finally, the model is employed to adres the problem of choosing an optimal pressing regime.