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951.
The structure of the nematic-isotropic interfacial layer is studied theoretically for systems formed by rod-like and persistent macromolecules. It is shown that the width of interfacial layer is normally of the order of the straight part of a molecule. This allows us to use the approach which describes intermolecular interactions phenomenologically (i.e. it allows us to consider all interactions), at the same time this approach describes molecular flexibility microscopically (i.e. it allows us to study the effects of flexibility correctly). It was found, that non-monotonic gradient profiles in the surface layer of the order parameter or of the concentration of molecules as a function of the coordinate perpendicular to the interface are possible. For example, a thin layer with abnormal ordering of molecules along the surface may exist near the interface for some systems. 相似文献
952.
E. V. Zakharov S. N. Levchenko Yu. Ya. Kharlanov 《Computational Mathematics and Modeling》1997,8(3):282-287
The article considers the mathematical model of a lens antenna in the shape of a homogeneous dielectric torus excited by an
axial magnetic dipole. The boundary-value problem for an elliptical differential equation is posed and reduced by the fundamental
solution method to an integral equation of 2nd kind over the torus section. A numerical algorithm is proposed, and the numerical
results are compared with experimental findings.
Translated from Obratnye Zadachi Estestvoznaniya, Published by Moscow University, Moscow, 1997, pp. 109–115. 相似文献
953.
The impurity weakening of crystalline NaCl:Mg and NaCl:Mn associated with purification of the matrix in a melt is demonstrated.
This effect is manifested in a consistent change in the yield strength and mobility of dislocations. Its unusual temperature
dependence is determined: in a number of cases weakening becomes greater as the temperature is lowered within the interval
293–4.2 K. A deviation in the elastic region of the stress-strain curves is observed to increase as the temperature is lowered.
Plasticizing of crystalline NaCl is established: when the deformation temperature is lowered from 293 to 77 and 4.2 K the
rate of rise in the yield strength of Cd2+ and Sr2+ doped samples is lower than that of undoped samples. An explanation for this fact is proposed.
Fiz. Tverd. Tela (St. Petersburg) 39, 313–317 (February 1997)
Deceased. 相似文献
954.
A system for display of magnetic resonance (MR) spectroscopic imaging (SI) data is described which provides for efficient review and analysis of the multidimensional spectroscopic and spatial data format of this technique. Features include the rapid display of spectra from selected image voxels, formation of spectroscopic images, spectral and image data processing operations, methods for correlating spectroscopic image data with high resolution 1H MR images, and hardcopy facilities. Examples are shown for 31P and 1H spectroscopic imaging studies obtained in human and rat brain. 相似文献
955.
956.
1IntroductionThispaperisconcernedwithpositivesolutionOfthesemilinearheatequationswithlocalizedreactionssubjecttoeitherinitialconditions(Cauchyproblem)ortheinitialandboundary-value(DirichletorNeumanntype)conditionswherenisaboundeddomaininRe,icEO.Equations(1.1)canbethoughtofasamodeltodescribesomephysicalphenomena(heatpropagation,chemicalreaction)inwhichthenonlinearreactionsinadynndcalsystemtakesplaceonlyatasinglesite.InthesequelforconvenienceweshallsamplycalltheCauchy,initial-Direchlet,orini… 相似文献
957.
958.
The Z0-boson contribution to the elastic scattering amplitude of an electron in an arbitrary plane-wave electromagnetic field is obtained. Special cases of the plane-wave field are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 33–39, February, 1991. 相似文献
959.
模糊集的分解集定理有两种形式,第一种形式与模糊集的λ—截集有关:A=其中A_λ是的λ—截集 ̄[1].第二种形式与集合套有关:其中H(λ)为集合套 ̄[2]或者A=其中H(λ)为集合套,Q为(0,1)的可列稠密子集_[3],.其实,这两种形式在本文提出的基本模糊集的概念下,可以统一起来成为任何模糊集可以分解为一些(可数或不可数)基本模糊集的和。不仅如此,本文还提出简单模糊集的概念,并证明了任何模糊集都可以表示成为可数个单调上升的简单模糊集的和,或等价地,可以表示成可数个单调上升的简单模糊集的极限,所用的证明方法是构造性的,所以对模糊集的结构也得出了一个清晰的认识. 相似文献
960.
We obtain equations that describe heat conduction of bodies spatially reinforced by a system of capillary tubes filled with a moving heat-tapping fluid. The corresponding initial boundary-value problem of heat conduction is formulated and qualitatively analyzed. For thin-walled structures, we present an algorithm for reduction of the three-dimensional problem to a two-dimensional one. Specific calculations in solving the formulated problem are performed in the stationary and axisymmetric cases for a conic shell of revolution. The influence of the reinforcement parameters (intensity and direction), velocity of fluid motion in thermal tubes, dimensions of the inner sections of the tubes, and cone angle of a shell on the temperature field is investigated. 相似文献