随机度量理论的最近进展及其应用

本文综述了随机度量理论在近十年来的重要进展及其具有代表性的某些应用。     

Thermomechanical stress fields in high-temperature fibrous composites. I: Unidirectional laminates

This two-part paper presents a closed-form procedure for evaluation of estimates of local thermomechanical stress fields in two-phase fibrous composites and laminates. The first part is concerned with a unidirectional elastic laminate subjected to uniform mechanical loads and to uniform changes in temperature. Both phases are assumed to be elastic, with temperature-dependent moduli and expansion coefficients; the solution reflects the influence of thermomechanical interactions. Exact solutions are not possible for any real system, because the local geometry is not known in detail. Instead, estimates of the fields are found from a modified Mori-Tanaka approximation. Examples are presented for two SiC/Ti---Al---Nb composites. Local stresses of interest are found after cooling from fabrication to room temperature. The presence of local yielding, and the influence of coupling terms on the local stress magnitudes are examined. Extension of the results to laminated plates is presented in Part II (Dvorak, G.J., Chen, T. & Teply, J., Composites Science and Technology, 43 (1992) 359–368, this issue).     

Convergence of iterated boolean sums of simultaneous approximants

Explicit error estimates are given for the iterated Boolean sum of a sequence of simultaneous approximants; the rate of convergence is shown to be improved for smooth functions. The general results are applied in the case of the Bernstein, Durrmeyer and Stancu operators.     

Unrestricted Hartree-Fock approximation of the extended emery model

We use an unrestricted self-consistent Hartree-Fock approach to calculate the nature of doping states in the three-band Hubbard model. It turns out that for physically relevant parameter values one hole is localized within a small spin-polarized region where five Cu spins are aligned in the same direction. The spin polarization and binding energy between these spinpolaronic states are investigated as a function of different parameters including a Holstein-type electron-phonon coupling on the Cu sites. At higher doping concentration we observe the occurrence of afmon states where the holes are localized in a ring-shaped area. Inside this ring the antiferromagnetic order parameter has inverse sign with respect to the residual antifer-romagnetically ordered plane.     

一种改进的辐射传输计算方法

精确、快速计算辐射传输一直是大气辐射学中的一个重要研究课题。我们在Knut Stamnes的离散纵标法（1988）[1]的基础之上,提出了一种辐射传输四流近似计算方法。该算法可以得到一个解析解,并且通过作数值计算,可以看到本算法的计算精度是令人满意的。     

Design Methodology of the Structure of Postal Express Mail Networks of Aviation Channels in China

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无染色牛肝过氧化氢酶薄晶的图象处理

本文根据Ｐ．Ｎ．Ｔ．Ｕｎｗｉｎ和Ｒ．Ｈｅｎｄｅｒｓｏｎ等人提出的对生物大分子晶体的囹象处理方法，对无染色的牛肝过氧化氢酶薄晶的显微象和衍射图进行了图象处理，最后得到了牛肝过氧化氢酶薄晶的二维结构。从中可以看出，牛肝过氧化氢酶薄晶的一个单胞由４个子胞组成，４个子胞排列方向各异。     

A NEW APPROACH FOR THE CLASSIFICATION AND ENUMERATION OF UNIQUE REACTION ROUTES AND UNIQUE OVERALL REACTIONS IN MULTIPLE CHEMICAL REACTION SYSTEMS

The methodology of response reactions (RERs) introduced earlier from thermodynamic and kinetic considerations is used in this work to develop a new algorithm for the classification and enumeration of unique/direct reaction routes (RRs) and overall reactions (ORs). According to the RERs approach, a unique set of both RRs and ORs may be generated starting from any conceivable set of linearly independent RRs and ORs. In particular, the direct ORs may be most conveniently enumerated starting from the formula matrix of the terminal species (reactants and products), i.e., without any relation to the elementary reactions comprising the detailed mechanism. Depending on the type of ORs produced by the RRs one can distinguish between two distinct types of direct RRs. Namely, one option is to define a direct RR by specifying the intermediate species that need to be eliminated. This type of RR is referred to as Milner RRs. The other option is to require the direct RRs to produce RERs, thus resulting in RRs referred to as Happel-Sellers RRs.     

FAFFA加速的PO-MM研究复杂金属载体上线天线电磁特性

本文提出了一种快速远场近似(FAFFA)加速的混合物理光学矩量法(POMM),利用FAFFA加速计算矩阵方程中的矩阵矢量积,明显提高了计算效率.对物体表面上的远场组之间的耦合作用推导出了一组简洁的计算公式,并分析了计算复杂度.复杂金属组合体上线天线输入导纳、互导纳和方向性图的计算结果与文献结果一致.利用该方法分析计算了一个舰船模型上线天线的电磁特性.数值结果表明了这种方法的正确性和工程应用中的有效性.     

Asymptotic stress intensity factor density profiles for smeared-tip method for cohesive fracture

The paper presents a computational approach and numerical data which facilitate the use of the smeared-tip method for cohesive fracture in large enough structures. In the recently developed K-version of the smeared tip method, the large-size asymptotic profile of the stress intensity factor density along a cohesive crack is considered as a material characteristic, which is uniquely related to the softening stress-displacement law of the cohesive crack. After reviewing the K-version, an accurate and efficient numerical algorithm for the computation of this asymptotic profile is presented. The algorithm is based on solving a singular Abel's integral equation. The profiles corresponding to various typical softening stress-displacement laws of the cohesive crack model are computed, tabulated and plotted. The profiles for a certain range of other typical softening laws can be approximately obtained by interpolation from the tables. Knowing the profile, one can obtain with the smeared-tip method an analytical expression for the large-size solution to fracture problems, including the first two asymptotic terms of the size effect law. Consequently, numerical solutions of the integral equations of the cohesive crack model as well as finite element simulations of the cohesive crack are made superfluous. However, when the fracture process zone is attached to a notch or to the body surface and the cohesive zone ends with a stress jump, the solution is expected to be accurate only for large-enough structures.