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81.
The adsorption of C2H4 on the FeNi(1 1 1) alloy surface has been studied by ASED-MO tight binding calculations. The C2H4 molecule presents its most stable geometry with the CC bond axis parallel to the surface along the [1, −1, 0] direction, bonded on top Fe atom and bonded along a Fe-Fe bridge site. As a consequence, the strength of the local Fe-Fe bond decreases between 37 and 62% of its original bulk value. This bond weakening is mainly due to the new C-Fe interactions however no Fe3C carbide formation is evidenced on surface. The Fe-Ni and Ni-Ni superficial bonds are only slightly modified. 相似文献
82.
Let S f be the finitary infinite symmetric group. For a certain class of irreducible unitary representations of S f , a version of Schur orthogonality relations is proved. That is, we construct an invariant inner product on the matrix coefficient space of each representation and show that matrix coefficients for distinct representations are orthogonal with respect to these norms. 相似文献
83.
Yongge Tian 《Linear and Multilinear Algebra》2013,61(2):125-131
After recalling the definition and some basic properties of finite hypergroups—a notion introduced in a recent paper by one of the authors—several non-trivial examples of such hypergroups are constructed. The examples typically consist of n n×n matrices, each of which is an appropriate polynomial in a certain tri-diagonal matrix. The crucial result required in the construction is the following: ‘let A be the matrix with ones on the super-and sub-diagonals, and with main diagonal given by a 1…a n which are non-negative integers that form either a non-decreasing or a symmetric unimodal sequence; then Ak =Pk (A) is a non-negative matrix, where pk denotes the characteristic polynomial of the top k× k principal submatrix of A, for k=1,…,n. The matrices Ak as well as the eigenvalues of A, are explicitly described in some special cases, such as (i) ai =0 for all ior (ii) ai =0 for i<n and an =1. Characters ot finite abelian hypergroups are defined, and that naturally leads to harmonic analysis on such hypergroups. 相似文献
84.
Aljaž Zalar 《代数通讯》2013,41(9):3420-3429
A linear polyomial non-negative on the non-negativity domain of finitely many linear polynomials can be expressed as their non-negative linear combination. Recently, under several additional assumptions, Helton, Klep, and McCullough extended this result to matrix polynomials. The aim of this article is to study which of these additional assumptions are really necessary. 相似文献
85.
Lambek extended the usual commutative ideal theory to ideals in noncommutative rings, calling an ideal A of a ring R symmetric if rst ∈ A implies rts ∈ A for r, s, t ∈ R. R is usually called symmetric if 0 is a symmetric ideal. This naturally gives rise to extending the study of symmetric ring property to the lattice of ideals. In the process, we introduce the concept of an ideal-symmetric ring. We first characterize the class of ideal-symmetric rings and show that this ideal-symmetric property is Morita invariant. We provide a method of constructing an ideal-symmetric ring (but not semiprime) from any given semiprime ring, noting that semiprime rings are ideal-symmetric. We investigate the structure of minimal ideal-symmetric rings completely, finding two kinds of basic forms of finite ideal-symmetric rings. It is also shown that the ideal-symmetric property can go up to right quotient rings in relation with regular elements. The polynomial ring R[x] over an ideal-symmetric ring R need not be ideal-symmetric, but it is shown that the factor ring R[x]/xnR[x] is ideal-symmetric over a semiprime ring R. 相似文献
86.
Cyclic posets are generalizations of cyclically ordered sets. In this article, we show that any cyclic poset gives rise to a Frobenius category over any discrete valuation ring R. The stable category of a Frobenius category is always triangulated and has a cluster structure in many cases. The continuous cluster categories of [14], the infinity-gon of [12], and the m-cluster category of type A ∞ (m ≥ 3) [13] are examples of this construction as well as some new examples such as the cluster category of ?2. An extension of this construction and further examples are given in [16]. 相似文献
87.
本实验建立了以抗坏血酸为基体改进剂测定蚝油中铅的方法。研究了多种基体改进剂消除蚝油基体对测铅的干扰,方法的相对标准偏差为4.9%,回收率为94%-96%,检出限为1.5ng/mL。本方法可用于蚝油、贻贝油等调味品中铅含量的测定。 相似文献
88.
The evaluation of matrix functions of the form f(A)v, where A is a large sparse or structured symmetric matrix, f is a nonlinear function, and v is a vector, is frequently subdivided into two steps: first an orthonormal basis of an extended Krylov subspace of fairly small dimension is determined, and then a projection onto this subspace is evaluated by a method designed for small problems. This paper derives short recursion relations for orthonormal bases of extended Krylov subspaces of the type Km,mi+1(A)=span{A-m+1v,…,A-1v,v,Av,…,Amiv}, m=1,2,3,…, with i a positive integer, and describes applications to the evaluation of matrix functions and the computation of rational Gauss quadrature rules. 相似文献
89.
利用已给出粗信息矩阵及粗集的有关理论,提出并研究了粗信息矩阵的两个数量特征--粗牲度短阵及粗精度矩阵,给出了一系列性质及定理. 相似文献
90.
通过静态批次实验研究旱田黄土对Pb(Ⅱ)和氯吡硫磷的共吸附行为,使用SEM,FTIR,XRD和理论分析揭示共吸附机制。实验结果发现:黄土对Pb(Ⅱ)和氯吡硫磷的共吸附符合Langmuir等温线方程,经计算得出的理论吸附容量qm分别为12.5和0.64mg.g-1,准二级动力学方程能更好地描述反应行为。吸附反应后,黄土表面形貌变化很小,FTIR图谱中的某些波峰红移、消失或强度减弱,综合XRD图谱及理论分析,认为:旱田黄土对Pb(Ⅱ)的吸附为表面配位络合和范德华力的作用,以化学吸附为主;而氯吡硫磷的去除涉及到黄土有机质对氯吡硫磷大分子的截留作用,以及氢键、范德华力的作用,以物理吸附为主,兼有化学吸附的贡献。旱田黄土有机质对Pb(Ⅱ)和氯吡硫磷的吸附有重要贡献。 相似文献