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1.
The amounts of decreased charge at Al sites of Al-based (Al–Pd–Cr–Fe, Al–Si–Mn, and Al–Re–Si) and at Zn sites of Zn-based (Zn–Mg–Zr) quasicrystals and approximant crystals were estimated. The evaluation was done by comparisons between chemical shifts experimentally observed by soft-X-ray emission spectroscopy and the amount of valence charge obtained by Bader analysis for first principle calculations of reference materials (Al, α-Al2O3, Zn, and ZnO). Decreased charges at Al sites of Al-based quasicrystals and at Zn sites of Zn-based quasicrystals were evaluated to be 1.0–2.5 e–/atom and 1.1–1.2 e–/atom, respectively. A covalent bonding nature alloy of Al–Re–Si also showed a decrease in valence charge at Al sites. 相似文献
2.
The zero field cooled (ZFC) and field cooled (FC) low-field magnetic moment m of a dense frozen ferrofluid containing Fe55Co45 particles of size 4.6nm in hexane exhibits irreversibility at temperatures T?T b≈ 30?K. FC in μ 0 H ≤ 1?T gives rise to shifted minor hysteresis loops below T b. At T c≈ 10?K, sharp peaks of m ZFC and of the ac susceptibility χ ′, a kink of the thermoremanent magnetic moment m TRM, a sizeable reduction of the coercive field H c, and the appearance of a spontaneous moment m SFM indicate a phase transition with near mean-field critical behaviour of both m SFM and χ ′ . These features are explained within a core-shell model of nanoparticles, whose strongly disordered shells gradually become blocked below T b, while their soft ferromagnetic cores couple dipolarly and become superferromagnetic (SFM) below T c. 相似文献
3.
G. Apreutesei 《Journal of Difference Equations and Applications》2013,19(5):511-527
The continuous dependence on data is studied for a class of second order difference equations governed by a maximal monotone operator A in a Hilbert space. A nonhomogeneous term f appears in the equation and some bilocal boundary conditions a, b are added. One shows that the function which associates to {a, b, A, f} the solution of this boundary value problem is continuous in a specific sense. One uses the convergence of a sequence of operators in the sense of the resolvent. The problem studied here is the discrete variant of a problem from the continuous case. 相似文献
4.
The Al45Cr7 compound is considered to exhibit an approximant structure of the icosahedral Al4Cr phase. Its (010) surface has been investigated in detail using density functional calculations. Surface energy calculations show that the stable terminations result from a cleavage of the crystal between adjacent atomic planes, in agreement with the layered structure of the compound. The integrity of the icosahedral atomic arrangements (icosahedral clusters) found in the bulk structure, is predicted to be removed at the surface. This result is in contrast to what has been previously concluded for the (010) surface of the Al13Fe4 quasicrystal approximant. Our findings are discussed in relation to the bonding network in the compound, calculated using the Crystal Orbital Hamiltonian Population approach, as possible reasons for such contrasted behavior. 相似文献
5.
The function-valued Padé-type approximant (FPTA) was defined in the inner product space [8]. In this work, we choose the coefficients in the Neumann power series to make the inner product with both sides a function-valued system of equations to yield a scalar system. Then we express an FPTA in the determinant form. To avoid the direct computation of the determinants, we present the E-algorithm for FPTA based on the vector-valued E-algorithm given by Brezinski [4]. The method of FPTA via E-algorithm (FPTAVEA) not only includes all previous methods but overcomes their essential difficulties. The numerical experiment for a typical integral equation [1] illustrates that the method of FPTAVEA is simpler and more effective for obtaining the characteristic values and the characteristic functions than all previous methods. In addition, this method is also applicable to other Fredholm integral equations of the second kind without explicit characteristic values and characteristic functions. A corresponding example [12] is given and the numerical result is the same as that in [12]. 相似文献
6.
We consider stochastic equations in Hilbert spaces with singular drift in the framework of [G. Da Prato, M. Röckner, Singular dissipative stochastic equations in Hilbert spaces, Probab. Theory Related Fields 124 (2) (2002) 261-303]. We prove a Harnack inequality (in the sense of [F.-Y. Wang, Logarithmic Sobolev inequalities on noncompact Riemannian manifolds, Probab. Theory Related Fields 109 (1997) 417-424]) for its transition semigroup and exploit its consequences. In particular, we prove regularizing and ultraboundedness properties of the transition semigroup as well as that the corresponding Kolmogorov operator has at most one infinitesimally invariant measure μ (satisfying some mild integrability conditions). Finally, we prove existence of such a measure μ for noncontinuous drifts. 相似文献
7.
In this work, we study the stability of the solution semigroup for some linear partial functional differential equations with infinite delay in a Banach space when the exponential stability fails. We use the so-called characteristic equation to compute the order of each pole of the resolvent operator associated with the infinitesimal generator of the solution semigroup. This result allows us to give sufficient conditions for having stability of the solution semigroup. 相似文献
8.
Abdel-Wahab M. Nourein 《BIT Numerical Mathematics》1976,16(3):291-297
In this paper we describe a new technique for generating iteration formulas — of arbitrary order — for determining a zero (assumed simple) of a functionf, assumed analytic in a region containing the zero. The 1/p Padé Approximant (p0) to the functiong(t)f(z) is formed wherez=w+t, using the Taylor series forf at the pointw, an approxination to the zero off. The value oft for which the 1/p Padé Approximant vanishes provides the basis of iteration formulas of orderp+2.Some known iteration formulas, e.g., Newton-Raphson's, Halley's and Kiss's of order of convergence two, three and four, are directly obtained by settingp=0,1 and 2, respectively. 相似文献
9.
This paper concerns with the study of a differential variational–hemivariational inequality (DVHVI, for short) in infinite-dimensional Banach spaces. We first introduce the new concept of gap functions for the variational control system of (DVHVI). Then, we consider two kinds of gap functions which are regularized gap function and Moreau–Yosida regularized gap function, respectively, and examine the relevant properties of the gap functions. Moreover, two global error bounds which depend implicitly on the regularized gap function and the Moreau–Yosida regularized gap function, accordingly, are obtained. Finally, in order to illustrate the applicability of the theoretical results, we investigate a coupled dynamic system which is formulated by a nonlinear reaction–diffusion equation described by a time-dependent nonsmooth semipermeability problem. 相似文献
10.
The Cauchy problem for the abstract semilinear evolution equation u′(t) = Au (t) + B (u (t)) + C (u (t)) is discussed in a general Banach space X. Here A is the so‐called Hille‐Yosida operator in X, B is a differentiable operator from D (A) into X, and C is a locally Lipschitz continuous operator from D (A) into itself. A vectorvalued functional defined only on X is used and appropriate conditions on the nonlinear operators B and C are imposed so that a vector‐valued functional defined on the domain of the operator A may be constructed in order to specify the growth of a global solution. The advantage of our formulation lies in the fact that it is possible to obtain a global solution by checking some energy inequalities concerning only low order derivatives (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献