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961.
B. Asenjo C. Guillén E. Saucedo D. Lincot M.T. Gutiérrez 《Journal of Physics and Chemistry of Solids》2010,71(12):1629-1633
In2S3 films have been chemically deposited on ITO coated glass substrates by chemical bath deposition, using different deposition times and precursor concentrations. The bilayers are intended for photovoltaic applications. Different characterization methods have been employed: optical properties of the films were investigated from transmittance measurements, structural properties by XRD and micro-Raman, and surface morphology by SEM microscopy analysis. Also, the direct and indirect band-gaps and the surface gap states were studied with surface photovoltage spectroscopy (SPS). We proposed that electronic properties of the In2S3 samples are controlled by two features: shallow tail states and a broad band centred at 1.5 eV approximately. Their relation with the structure is discussed, suggesting that their origin is related to defects created on the S sub-lattice, and then both defects are intrinsic to the material. 相似文献
962.
We prove that several types of open Riemann surfaces, including the finitely connected planar domains, embed properly into
such that the values on any given discrete sequence can be arbitrarily prescribed.
Kutzschebauch supported by Schweizerische Nationalfonds grant 200021-107477/1. 相似文献
963.
T. E. Bulgakova A. V. Voytishek 《Computational Mathematics and Mathematical Physics》2009,49(7):1093-1102
Selection of conditionally optimal parameters of the randomized iterative method for solving large-scale linear systems of equations is considered. The error of this method is analyzed by analogy with the functional Monte Carlo algorithms. For the simple iteration method, the “column” randomization of the matrix is thoroughly analyzed. 相似文献
964.
For a fixed value of a parameter k≥2, the Maximum k-Edge-Colorable Subgraph Problem consists in finding k edge-disjoint matchings in a simple graph, with the goal of maximising the total number of edges used. The problem is known to be -hard for all k, but there exist polynomial time approximation algorithms with approximation ratios tending to 1 as k tends to infinity. Herein we propose improved approximation algorithms for the cases of k=2 and k=3, having approximation ratios of 5/6 and 4/5, respectively. 相似文献
965.
We study the complexity of the problem of deciding the existence of a spanning subgraph of a given graph, and of that of finding a maximum (weight) such subgraph. We establish some general relations between these problems, and we use these relations to obtain new NP-completeness results for maximum (weight) spanning subgraph problems from analogous results for existence problems and from results in extremal graph theory. On the positive side, we provide a decomposition method for the maximum (weight) spanning chordal subgraph problem that can be used, e.g., to obtain a linear (or O(nlogn)) time algorithm for such problems in graphs with vertex degree bounded by 3. 相似文献
966.
Shadow systems are often used to approximate reaction-diffusion systems when one of the diffusion rates is large. In this paper, we study the global existence and blow-up phenomena for shadow systems. Our results show that even for these fundamental aspects, there are serious discrepancies between the dynamics of the reaction-diffusion systems and that of their corresponding shadow systems. 相似文献
967.
We are interested in nonlocal eikonal equations describing the evolution of interfaces moving with a nonlocal, non-monotone velocity. For these equations, only the existence of global-in-time weak solutions is available in some particular cases. In this paper, we propose a new approach for proving uniqueness of the solution when the front is expanding. This approach simplifies and extends existing results for dislocation dynamics. It also provides the first uniqueness result for a Fitzhugh-Nagumo system. The key ingredients are some new perimeter estimates for the evolving fronts as well as some uniform interior cone property for these fronts. 相似文献
968.
Christian Liedtke 《Journal of Pure and Applied Algebra》2009,213(5):737-741
The Picard scheme of a smooth curve and a smooth complex variety is reduced. In this note we discuss which classes of surfaces in terms of the Enriques-Kodaira classification can have non-reduced Picard schemes and whether there are restrictions on the characteristic of the ground field. It turns out that non-reduced Picard schemes are uncommon in Kodaira dimension κ≤0, that this phenomenon can be bounded for κ=2 (general type) and that it is as bad as can be for κ=1. 相似文献
969.
Mark Wildon 《Journal of Pure and Applied Algebra》2009,213(7):1464-1477
Building on work of Saxl, we classify the multiplicity-free permutation characters of all symmetric groups of degree 66 or more. A corollary is a complete list of the irreducible characters of symmetric groups (again of degree 66 or more) which may appear in a multiplicity-free permutation representation. The multiplicity-free characters in a related family of monomial characters are also classified. We end by investigating a consequence of these results for Specht filtrations of permutation modules defined over fields of prime characteristic. 相似文献
970.
Duong Quoc Viet 《Journal of Pure and Applied Algebra》2009,213(11):2104-2116
Let A be a Noetherian local ring with the maximal ideal m and an m-primary ideal J. Let S=?n≥0Sn be a finitely generated standard graded algebra over A. Set S+=?n>0Sn. Denote by FJ(S)=?n≥0→(Sn/JSn) the fiber cone of S with respect to J. The paper characterizes the multiplicity and the Cohen-Macaulayness of FJ(S) in terms of minimal reductions of S+. 相似文献