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951.
Using first-principles density functional theory within the generalized gradient approximation method, the effect of Zn doping on electronic and magnetic properties of NiFe2O4 ferrite spinel has been studied. The crystal structure of the compounds is assigned to a pseudocubic structure and the lattice constant increases as the Zn concentration increases. Our spin-polarized calculations give a half-metallic state for NiFe2O4 and a normal metal state for ZnxNi1−xFe2O4 (0<x≤0.5). Based on the magnetic properties calculations, it is found that the saturation magnetic moment enhances linearly with increase in the Zn content in NiFe2O4. The Zn doping in NiFe2O4 also induces strong ferrimagnetism since it decreases the magnetic moment of A-sites. 相似文献
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953.
In this paper, we propose two kinds of optimality concepts, called the sharp minima and the weak sharp minima, for a constrained set-valued optimization problem. Subsequently, we extend the Fermat rules for the local minima of the constrained set-valued optimization problem to the sharp minima and the weak sharp minima in Banach spaces or Asplund spaces, by means of the Mordukhovich generalized differentiation and the normal cone. As applications, we investigate the generalized inequality systems with constraints, and get some characterizations of error bounds for the constrained generalized inequality systems in convex and nonconvex cases. 相似文献
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L. Wang H. P. Dai H. Dong Y. Y. Cao Y. X. Sun 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(3):335-342
This paper considers the problem of controlling
weighted complex dynamical networks by applying adaptive control
to a fraction of network nodes. We investigate the local and
global synchronization of the controlled dynamical network through
the construction of a master stability function and a Lyapunov
function. Analytical results show that a certain number of nodes
can be controlled by using adaptive pinning to ensure the
synchronization of the entire network. We present numerical
simulations to verify the effectiveness of the proposed scheme. In
comparison with feedback pinning, the proposed pinning control
scheme is robust when tested by noise, different weighting and
coupling structures, and time delays. 相似文献
959.
A unified boundary integral equation (BIE) is developed for the scattering of elastic and acoustic waves. Traditionally, the elastic and acoustic wave problems are solved separately with different BIEs. The elastic wave case is represented in a vector BIE with the traction and displacement vectors as unknowns whereas the acoustic wave case is governed by a scalar BIE with velocity potential or pressure as unknowns. Although these two waves can be unified in the form of a partial differential equation, the unified form in its BIE counterpart has not been reported. In this work, we derive the unified BIE for these two waves and then show that the acoustic wave case can be derived from this BIE by introducing a shielding loss for small shear modulus approximation; hence only one code needs to be maintained for both elastic and acoustic wave scattering. We also derive the asymptotic Green's tensor for zero shear modulus and solve the corresponding vector equation. We employ the method of moments, which has been widely used in electromagnetics, as a numerical tool to solve the BIEs involved. Our numerical experiments show that it can also be used robustly in elastodynamics and acoustics. 相似文献
960.
A field method for integrating the equations of motion of mechanico--electrical coupling dynamical systems
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A field method for integrating the equations of motion for mechanico-electrical coupling dynamical systems is studied. Two examples in mechanico-electrical engineering are given to illustrate this method. 相似文献