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941.
Monopoles and vortices are well known magnetically charged soliton solutions of gauge field equations. Extending the idea of Dirac on monopoles, Schwinger pioneered the concept of solitons carrying both electric and magnetic charges, called dyons, which are useful in modeling elementary particles. Mathematically, the existence of dyons presents interesting variational partial differential equation problems, subject to topological constraints. This article is a survey on recent progress in the study of dyons. 相似文献
942.
特异的柴胡皂苷糖苷酶的分离纯化 总被引:1,自引:0,他引:1
研究了微生物Aspergillus oryzaec42菌株产特异的柴胡皂苷糖苷酶的分离纯化及其酶学性质.结果表明,该酶能够水解柴胡皂苷A或柴胡皂苷B2侧链的3-O-β-(1→3)-Glc和3-O-β-Fuc,其分子量约为58000.柴胡皂苷糖苷酶首先水解柴胡皂苷A或B2侧链的3-O-β-(1→3)-Glc生成3-O-β-Fuc-柴胡皂苷元A或B2,然后进一步水解3-O-β-Fuc-柴胡皂苷元A或B2的3-O-β-Fuc生成柴胡皂苷元A或B2.柴胡皂苷糖苷酶的最适反应温度为4℃,最适pH值为5.0;Na+和K+对酶活力的影响不明显;Cu2+,Hg2+和Ag+对酶活力有显著的抑制作用;Ca2+和Mg2+对酶活力有轻微的激活作用. 相似文献
943.
A fringe analysis method, which combines the Fourier transform with the fractional fringe order method for measuring the absolute thickness of a block gauge, is presented. An approximate integer part of the fringe order is estimated by mechanical measurements, and the fractional part is determined by Fourier analysis of the interferometric fringe patterns. The fringe patterns are obtained with a Michelson interferometer by illumination of several selected wavelengths, respectively. The use of the fractional fringe order method can determine accurately more than 2ϖ phase jumps. The measured thickness of a block gauge is 5999115.0 ± 0.7 nm, which is comparable with the standard thickness of 6 mm. The influence of wavelength and approximate integer part of fringe order on the measurement accuracy is discussed. 相似文献
944.
Left-right symmetric models are analyzed within the context of noncommutative geometry where we show that spontaneous parity violation is ruled out. 相似文献
945.
946.
A coupled isotropic-kinematic hardening material model was developed based on phenomenological observations of performed two stage experiments on a medium carbon steel – SAE 1144, where the first deformation is performed at elevated temperatures and the second deformation at room temperature. Above all, deformations with orthogonal loading at various temperatures were investigated in order to determine the influence of the loading direction as well as of the temperature. Bergström’s theory of work hardening as well as the nonlinear kinematic hardening of an Armstrong–Frederick type were used as a basis for the model development. In the proposed model a relationship between material coefficients of the classical Bergström model and temperature was investigated. The aim of the new material model was to introduce the least possible amount of new parameters as well as to facilitate the mathematical determination of parameters during the fitting of the model with experimental data. The developed model was implemented in an in-house FE-Code in order to simulate the material behavior due to the dynamic strain aging and the hardening behavior after the dynamic strain aging process. Representative simulation results were compared with the experimental data in order to validate the efficiency and the application range of the model. 相似文献
947.
F. Ashida 《Archive of Applied Mechanics (Ingenieur Archiv)》2001,71(4-5):221-232
Summary The present paper discusses a plane strain problem of transient thermoelasticity in a circular cylinder which is in partial
contact with two heated rigid stamps, in the case where the coefficient of relative heat transfer on the contact surface of
the cylinder is different from that on the traction-free surface. A finite difference method with respect to the time variable
and Airy's thermal stress function is employed to analyze the temperature and thermoelastic fields. The problem is formulated
in terms of two dual-series equations derived not only from the thermal boundary conditions but also from the mechanical boundary
conditions. Since the radial, hoop and axial stresses have singularities at the end of the contact surface of the cylinder,
the stress singularity coefficients are defined and then the relationship among these three coefficients is also obtained.
Finally, numerical results are illustrated graphically.
Received 3 March 2000; accepted for publication 12 July 2000 相似文献
948.
V. Nistor 《Acta Mathematica Hungarica》2003,99(1-2):155-183
We define the gauge-equivariant index of a family of elliptic operators invariant with respect to the free action of a family
of Lie groups (these families are called ``gauge-invariant families' in what follows). If the fibers of
are simply-connected and solvable, we compute the Chern character of the gauge-equivariant index, the result being given
by an Atiyah–Singer type formula that incorporates also topological information on the bundle
. The algebras of invariant pseudodifferential operators that we study,
and
, are generalizations of ``parameter dependent' algebras of pseudodifferential operators (with parameter in R
q), so our results provide also an index theorem for elliptic, parameter dependent pseudodifferential operators. We apply these
results to study Fredholm boundary conditions on a simplex.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
949.
Downward Sets and their separation and approximation properties 总被引:1,自引:1,他引:0
We develop a theory of downward subsets of the space I, where I is a finite index set. Downward sets arise as the set of all solutions of a system of inequalities xI,ft(x)0 (tT), where T is an arbitrary index set and each f
t (tT) is an increasing function defined on I. These sets play an important role in some parts of mathematical economics and game theory. We examine some functions related to a downward set (the distance to this set and the plus-Minkowski gauge of this set, which we introduce here) and study lattices of closed downward sets and of corresponding distance functions. We discuss two kinds of duality for downward sets, based on multiplicative and additive min-type functions, respectively, and corresponding separation properties, and we give some characterizations of best approximations by downward sets. Some links between the multiplicative and additive cases are established. 相似文献
950.
Uniaxial compression tests have been conducted on Jinan gabbro at six different axial strain rates ranging from 10~(-8)/s to 10~(-3)/s. Results show that the strength decreases by about 23% with decreasing strain rate. The stress level C_0~' /or the onset of dilatancy is constant for six strain rates. When σ_1>C_o~' ε_1 and D increase with decreasing strain rate (?) under a specific stress level.Microscopic observations on the stressed rock samples reveal that the density of microcracks for the samples loaded at low strain rates is higher than that at high strain rates; in addition there are also cracks nearly perpendicular to it, which is responsible for the increase of D value.The creep test under the stress σ_(σ_1>C_0~') confirms that the growth of microcracks in the rock has been time-dependent effects, and the steady-state creep with (?)=constant developed until the rock fails.Summing up the above reslts shows that when σ>C_0~', the constitution law of the rockswill be time-dependent, and the 相似文献