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41.
First-principles study on the structure instability and electronic structure of cubic Ba0.5Sr0.5TiO3
Yuan Xu Wang 《Solid State Communications》2005,135(5):290-293
We present first-principles calculations on the structure instability and the electronic structure properties of cubic Ba0.5Sr0.5TiO3 (BST). The calculated total energy result shows that the Sr ions have a more important effect on the structure instability of BST system than the Ba ions. The off-center displacement of the Sr ions will lower the system energy and makes it instable. In order to understand the interaction between ions, the density of states and the charge density distribution were calculated. From the analysis of the density of states, we conclude that the hybridization between Ba p and O p is stronger than that between Sr p and O p. This is consistent with the analysis of the charge density distribution. 相似文献
42.
王开弘 《数学的实践与认识》2008,38(12):141-144
通过对q元线性码广义Hamming重量dr(·)的分析,应用支撑重量ωs(C)的性质,再次分析了q元[n,k]线性码广义Griesmer界n≥dr+sum from i=1 to k-r[(q-1)dr/qi(qr-1)]. 相似文献
43.
This is the fourth article of our series. Here, we study weighted norm inequalities for the Riesz transform of the Laplace–Beltrami
operator on Riemannian manifolds and of subelliptic sum of squares on Lie groups, under the doubling volume property and Gaussian
upper bounds.
相似文献
44.
《Applied Mathematical Modelling》2014,38(15-16):3890-3896
Data envelopment analysis (DEA) is a linear programming technique that is used to measure the relative efficiency of decision-making units (DMUs). Liu et al. (2008) [13] used common weights analysis (CWA) methodology to generate a CSW using linear programming. They classified the DMUs as CWA-efficient and CWA-inefficient DMUs and ranked the DMUs using CWA-ranking rules. The aim of this study is to show that the criteria used by Liu et al. are not theoretically strong enough to discriminate among the CWA-efficient DMUs with equal efficiency. Moreover, there is no guarantee that their proposed model can select one optimal solution from the alternative components. The optimal solution is considered to be the only unique optimal solution. This study shows that the proposal by Liu et al. is not generally correct. The claims made by the authors against the theorem proposed by Liu et al. are fully supported using two counter examples. 相似文献
45.
We give sufficient conditions on a real number β and on a closed set F in a general space of homogeneous type (X,d,μ) in such a way that μ(B(x,d(x,F)))β becomes a Muckenhoupt weight. In order to prove our result, we modify the underlying space so that it becomes 1-Ahlfors regular. 相似文献
46.
《数学学报》2014,(5)
<正>Weighted Estimates for Multilinear Pseudodifferential Operators Kang Wei LI;;Wen Chang SUN Abstract In this paper,we study the weighted estimates for multilinear pseudodifferential operators.We show that a multilinear pseudodifferential operator is bounded with respect to multiple weights whenever its symbol satisfies some smoothness and decay conditions.Our result generalizes similar ones from the classical A_p weights to multiple weights.Trigonometric Series With a Generalized Monotonicity Condition 相似文献
47.
Byeong Seok Ahn 《European Journal of Operational Research》2011,212(3):552-559
In a situation where imprecise attribute weights such as a rank order are captured, various approximate weighting methods have been proposed to aid multiattribute decision analysis. Among others, it is well known that the rank order centroid (ROC) weights result in the highest performance in terms of the identification of the best alternative under the ranked attribute weights. In this paper, we aim to reinterpret the meaning of the ROC weights and to develop a compatible weighting method that is based on other well-established academic disciplines. The ordered weighted averaging (OWA) method is a nonlinear aggregation method in that the weights are associated with the objects reordered according to their magnitudes in the aggregation process. Some interesting semantics can be attached to the approximate weights in view of the measure developed in the OWA method. Furthermore, the weights generated by the maximum entropy method show equally compatible performance with the ROC weights under some condition, which is demonstrated by theoretical and simulation analysis. 相似文献
48.
Thomas Schott 《Mathematische Nachrichten》1998,189(1):221-242
In this paper we define weighted function spaces of type Bspq(u) and Fspq(u) on the Euclidean space IRn, where u is a weight function of at most exponential growth. In particular, u(x) = exp(±|χ|) is an admissible weight. We prove some basic properties of these spaces, such as completeness and density of the smooth functions. 相似文献
49.
We improve upon the method of Zhu and Zhu [A method for directly finding the denominator values of rational interpolants, J. Comput. Appl. Math. 148 (2002) 341–348] for finding the denominator values of rational interpolants, reducing considerably the number of arithmetical operations required for their computation. In a second stage, we determine the points (if existent) which can be discarded from the rational interpolation problem. Furthermore, when the interpolant has a linear denominator, we obtain a formula for the barycentric weights which is simpler than the one found by Berrut and Mittelmann [Matrices for the direct determination of the barycentric weights of rational interpolation, J. Comput. Appl. Math. 78 (1997) 355–370]. Subsequently, we give a necessary and sufficient condition for the rational interpolant to have a pole. 相似文献
50.
Pierre Dreyfuss 《Potential Analysis》2007,26(2):101-119
We prove that under some global conditions on the maximum and the minimum eigenvalue of the matrix of the coefficients, the gradient of the (weak) solution of some degenerate elliptic equations has higher integrability than expected. Technically we adapt the Giaquinta–Modica regularity method in some degenerate cases. When the dimension is two, a consequence of our result is a new Hölder continuity result for the weak solution. 相似文献