一类广义非线性隐拟变分包含

引入和研究了一类新的涉及集值极大单调映象的广义非线性隐拟变分包含.对此类变分包含在没有紧性假设下证明了解的存在定理.为寻求此类变分包含的近似解,建议和分析了一个新的迭代算法.给出了由新算法产生的迭代序列的收敛性.作为特殊情形,也讨论了在此领域内的某些已知结果.     

On coupled gradient-dependent plasticity and damage theories with a view to localization analysis

Combinations of gradient plasticity with scalar damage and of gradient damage with isotropic plasticity are proposed and implemented within a consistently linearized format. Both constitutive models incorporate a Laplacian of a strain measure and an internal length parameter associated with it, which makes them suitable for localization analysis.The theories are used for finite element simulations of localization in a one-dimensional model problem. The physical relevance of coupling hardening/softening plasticity with damage governed by different damage evolution functions is discussed. The sensitivity of the results with respect to the discretization and to some model parameters is analyzed. The model which combines gradient-damage with hardening plasticity is used to predict fracture mechanisms in a Compact Tension test.     

Distribution and speciation of platinum group elements in environmental matrices

The use of platinum group elements (PGEs) as components of autocatalytic converters attached to motor vehicles has resulted in serious contamination of the environment by Pt, Rh and Pd in nanocrystalline forms. Trace concentrations of PGEs, particularly the major component Pt, in environmental samples have been measured by sensitive instrumental procedures. These data have raised further questions about the nature of Pt species in contaminated soils and in plants grown in them. The focus of attention is changing from accumulations of data expressing total concentrations to investigations of speciation. Application of analytical procedures for research on speciation has provided information concerning transformations of Pt compounds in contaminated soils, the uptake of Pt by plants and the nature of Pt compounds in vegetation. Determination of background levels of precious metals in clinical and environmental matrices has required the development of analytical methods which combine uses of minimal quantities of reagents, and as small a number of chemical operations as possible to yield very low procedural blanks. Sensitive instrumental methods based upon high resolution inductively coupled plasma mass spectrometry and adsorptive stripping voltammetry have proven to be valuable for this work.     

部分药、食两用花卉中微量元素含量分析

采用原子吸收分光光度法对部分药、食两用花卉中微量元素进行了分析,并与普通叶菜类进行了对比。     

ICP-AES法测定环境水样中的微量镉铬铜镍铅锌

应用ＩＣＰ－ＡＥＳ法对环境水样中Ｃｄ、Ｃｒ、Ｃｕ、Ｎｉ、Ｐｂ、Ｚｎ等６种微量元素进行直接测定。考察了环境水样中钙、镁离子对的影响。通过对国标样品及实际样品的测定,加标回收实验,建立了简便、快速、准确、稳定、重现性较好的ＩＣＰ－ＡＥＳ法测定环境水样中６种微量元素的分析方法。     

核子微探针在医学和生物学中的应用

生命科学中微量元素研究需要发展一种能在细胞水平上测量生物组织中元素分布的仪器或技术,核子微探针的发展使这种研究成为可能。本文简述了核子微探针的最新发展及其在医学、细胞药物学和细胞谱系中的某些应用。     

ICP-AES法同时测定人发中9种元素含量

应用电感耦合等离子体发射光谱法对煤矿井下人员头发中９种元素含量进行了测定,此实验结果为矿井下环境污染情况的研究提供了一定的科学依据。     

ON THE MAXIMAL LYAPUNOV EXPONENT FOR A REAL NOISE PARAMETRICALLY EXCITED CO-DIMENSION TWO BIFURCATION SYSTEM (Ⅱ)

ＴｈｅｄｅｃｉｓｉｖｅｅｆｆｅｃｔｓｏｆｓｉｎｇｕｌａｒｐｏｉｎｔｓａｎｄｂｏｕｎｄａｒｉｅｓｂｅｌｏｎｇｉｎｇｔｏｓｏｌｕｔｉｏｎｐｒｏｃｅｓｓｅｓｏｆＩｔｏｓｔｏｃｈａｓｔｉｃｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓｏｎｔｈｅｓｉｔｕａｔｉｏｎｓｏｆｄｉｓｔｒｉｂｕｔｉｏｎｓｏｆｅｒｇｏｄｉｃｃｏｍｐｏｎｅｎｔｓ,ｔｈｅｅｘｉｓｔｅｎｃｅａｎｄｔｈｅｆｏｒｍｓｏｆｉｎｖａｒｉａｂｌｅｍｅａｓｕｒｅｓ,ｔｈｅｓａｍｐｌｅｐｒｏｐｅｒｔｉｅｓ（ｉｎｃｌｕｄｉｎｇｓａｍｐｌｅｓｔａｂｉｌｉｔｙ）…     

A general mixed covolume framework for constructing conservative schemes for elliptic problems

We present a general framework for the finite volume or covolume schemes developed for second order elliptic problems in mixed form, i.e., written as first order systems. We connect these schemes to standard mixed finite element methods via a one-to-one transfer operator between trial and test spaces. In the nonsymmetric case (convection-diffusion equation) we show one-half order convergence rate for the flux variable which is approximated either by the lowest order Raviart-Thomas space or by its image in the space of discontinuous piecewise constants. In the symmetric case (diffusion equation) a first order convergence rate is obtained for both the state variable (e.g., concentration) and its flux. Numerical experiments are included.

     

Low-voltage low-temperature electroluminescence of CdF2-RE thin films

Different electroluminescence spectrums of the blueλ _max =420 nm wide-banded low-temperature low-voltage radiation of CdF₂-RE films at different levels of excitation in the region of temperatures of 77–300K are investigated. The kinetic characteristics and temperature dependence of this radiation are explored. An effect of the resonance interaction of the centers of luminescence of the wide-band and line radiation of the RE-centers is found. A model of the center of the wide-band radiation is suggested. It is shown that the “blue” radiation is caused by recombination of the carriers. Institute of Physics of Semiconductors of the National Academy of Sciences of Ukraine, Nauka Ave., 45, 252028, Kiev. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 127–132, January–February, 1999.