On Weak Regular ^＊-semigroups

In this paper, a special kind of partial algebras called projective partial groupoids is defined.It is proved that the inverse image of all projections of a fundamental weak regular ^*-semigroup under the homomorphism induced by the maximum idempotent-separating congruence of a weak regular ^*-semigroup has a projective partial groupoid structure. Moreover, a weak regular ^*-product which connects a fundamental weak regular ^*-semigroup with corresponding projective partial groupoid is defined and characterized. It is finally proved that every weak regular ^*-product is in fact a weak regular ^*-semigroup and any weak regular ^*-semigroup is constructed in this way.     

一般状态空间跳过程不变测度的存在性和唯一性

本文利用一般状态空间马氏链关于不变测度的有关结果和跳过程的性质，研究了一般状态空间跳过程不变测度的存在性和唯一性。     

LOAD CAPACITY OF OILFILM——LUBRICATED BALL-BEARING WITH SPIRAL GROOVES

In order to improve load capacity and stability of a fluid moving-pressure bearing, at present, measure of cutting grooves on a turning-shaft is generally adopted.The performances of spiral grooves are better in various groovetypes. Therefore, a theoretical analysis and an experimental investigation of the bearing with spiral grooves attract general attention. But the results of most articles published in china are numerical solutions of the computer. Using the methods of parameter perturbation in the paper, an approaching analytical solution of Reynolds equation of the moving-pressure oilfilm-lubricated ball-bearing with spiral grooves has been obtained. We have combined the numerical solutions of the computer, and the influence of the bearing parameters upon the load capacity is discussed; the optimum values of the groove parameter are obtained. The theoretical conclusion of this paper is in good agreement with the experimental data obtained by 651 Institute.     

On Moments of Folded and Truncated Multivariate Normal Distributions

Recurrence relations for integrals that involve the density of multivariate normal distributions are developed. These recursions allow fast computation of the moments of folded and truncated multivariate normal distributions. Besides being numerically efficient, the proposed recursions also allow us to obtain explicit expressions of low-order moments of folded and truncated multivariate normal distributions. Supplementary material for this article is available online.     

Inversions of Hölder’s Inequality

Mathematical Notes - In the present paper, new theorems on the inversion of the Hölder inequality that refine similar inversions known previously are proved.     

NiTi形状记忆合金热-力耦合循环变形行为宏微观实验和理论研究进展

论文对NiTi形状记忆合金热-力耦合循环变形行为研究的最新进展进行综述和评价.首先总结NiTi形状记忆合金在循环加载条件下的单轴、非比例多轴循环变形特性以及强烈的热-力耦合特性,阐述NiTi形状记忆合金在循环变形过程中出现功能性劣化的微观机理;然后,讨论在宏观和细观尺度上建立的三类NiTi形状记忆合金典型的循环本构模型,并评述代表性模型的预测能力;最后,总结已有研究存在的不足,对相关问题的进一步研究提出建议.在本构模型方面主要介绍了作者及其合作者在基于晶体塑性的热-力耦合循环本构模型方面的工作,突出了多种非弹性变形机制和强烈热-力耦合行为对形状记忆合金循环变形行为的影响.     

Oliver–Pharr indentation method in determining elastic moduli of shape memory alloys—A phase transformable material

Instrumented indentation test has been extensively applied to study the mechanical properties such as elastic modulus of different materials. The Oliver–Pharr method to measure the elastic modulus from an indentation test was originally developed for single phase materials. During a spherical indentation test on shape memory alloys (SMAs), both austenite and martensite phases exist and evolve in the specimen due to stress-induced phase transformation. The question, “What is the measured indentation modulus by using the Oliver–Pharr method from a spherical indentation test on SMAs?” is answered in this paper. The finite element method, combined with dimensional analysis, was applied to simulate a series of spherical indentation tests on SMAs. Our numerical results indicate that the measured indentation modulus strongly depends on the elastic moduli of the two phases, the indentation depth, the forward transformation stress, the transformation hardening coefficient and the maximum transformation strain. Furthermore, a method based on theoretical analysis and numerical simulation was established to determine the elastic moduli of austenite and martensite by using the spherical indentation test and the Oliver–Pharr method. Our numerical experiments confirmed that the proposed method can be applied in practice with satisfactory accuracy. The research approach and findings can also be applied to the indentation of other types of phase transformable materials.     

45fs钛宝石强激光场中Ar与Ne气的高次谐波辐射的实验研究 *

以Ar气为工作介质 ,研究了激光强度、工作介质密度对高次谐波辐射的影响 .结果表明 ,足够高的激光强度和气体密度是获得更大强度更高次谐波的基本条件 .观察到可分辨的最高谐波次数为第81次(相应的波长为969nm) ,不可分辨的谐波辐射不低于第91次 (相应的波长为863nm) ,这是目前世界上从Ar气中观察到的最高级次(最短波长)的谐波辐射 .理论分析表明 ,更高次谐波是从Ar⁺产生的 .以Ne气为工作介质 ,通过观察Ne⁺的特征谱线 ,研究了气体电离产生的自由电子对高次谐波辐射的破坏作用 .目前 ,以Ne气为工作介质观察到的可分辨的最高次谐波为第107次(相应波长为7.33nm) .而观察到的不可分辨的谐波辐射不低于第131次谐波(相应波长短于5.99nm) .     

General theory for the ferroelectric polarization induced by spin-spiral order

The ferroelectric polarization of triangular-lattice antiferromagnets induced by helical spin-spiral order is not explained by any existing model of magnetic-order-driven ferroelectricity. We resolve this problem by developing a general theory for the ferroelectric polarization induced by spin-spiral order and then by evaluating the coefficients needed to specify the general theory on the basis of density functional calculations. Our theory correctly describes the ferroelectricity of triangular-lattice antiferromagnets driven by helical spin-spiral order and incorporates known models of magnetic-order-driven ferroelectricity as special cases.     

还原偶氮测定硝基苯方法中样品背景存在的问题及改进

对还原偶氮法测定水中硝基苯分析方法中样品背景等方面存在的问题,以及对分析测定产生的影响进行了较为深入的分析和研究;提出了测定方法的改进意见.并通过硝基苯环境标准样品的实际测定,对改进前后的方法进行了对比和验证,取得了满意的结果.