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991.
Erd?s, Freud and Hegyvári [1] constructed a permutation a 1,a 2,… of positive integers with \([a_{i}, a_{i+1}]< i\exp \left\{c\sqrt{\log i}\log\log i\,\right\}\) for an absolute constant c>0 and all i≧3. In this note, we construct a permutation of all positive integers such that for any ε>0 there exists an i 0 with \([a_{i}, a_{i+1}]\allowbreak < i\exp \left\{\left(2\sqrt{2}+\varepsilon\right) \sqrt{\log i\log\log i}\,\right\}\) for all i≧i 0. 相似文献
992.
Łukasz Kosiński 《Journal of Geometric Analysis》2011,21(4):902-919
We give a characterization of non-hyperbolic pseudoconvex Reinhardt domains in ℂ2 for which the answer to the Serre problem is positive. Moreover, all non-hyperbolic pseudoconvex Reinhardt domains in ℂ2 with non-compact automorphism group are explicitly described. 相似文献
993.
We consider a subproblem in parameter estimation using the Gauss-Newton algorithm with regularization for NURBS curve fitting. The NURBS curve is fitted to a set of data points in least-squares sense, where the sum of squared orthogonal distances is minimized. Control-points and weights are estimated. The knot-vector and the degree of the NURBS curve are kept constant. In the Gauss-Newton algorithm, a search direction is obtained from a linear overdetermined system with a Jacobian and a residual vector. Because of the properties of our problem, the Jacobian has a particular sparse structure which is suitable for performing a splitting of variables. We are handling the computational problems and report the obtained accuracy using different methods, and the elapsed real computational time. The splitting of variables is a two times faster method than using plain normal equations. 相似文献
994.
In this paper, we prove the existence, uniqueness and the stability of solutions for some nonlinear functional-integral equations by using generalized Lipschitz condition. We prove a fixed point theorem to obtain the mentioned aims in Banach space X:= C([a, b],R). As application we study some Volterra integral equations with linear, nonlinear and singular kernel. 相似文献
995.
光子晶体异质结耦合波导光开关 总被引:2,自引:0,他引:2
以二维三角晶格光子晶体为研究对象,在该光子晶体中引入两行平行的单模线缺陷波导,以一行耦合介质柱为间距,通过调节部分耦合介质柱的折射率,构筑了光子晶体异质结耦合波导光开关结构。利用平面波展开法和定向耦合原理计算了在不同入射光频率下,缺陷波导间耦合介质柱的折射率不同时的耦合长度,确定了合适的光子晶体异质结耦合波导光开关的结构参数。利用时域有限差分法研究了该光开关中耦合介质柱的折射率变化及异质结构介质柱的位置分布对光信号输出路径的影响。结果表明,通过改变该结构中耦合介质柱的折射率可以改变光的输出路径,可实现光的开关行为。并且异质结构介质柱位置的随机分布对该光开关的影响不大,有助于光子晶体新型滤波器、定向耦合器、波分复用器以及光开关等光子器件的研究。 相似文献
996.
A theoretical investigation is reported of the fine structure levels and the spin-singlet contributions to zero-field-splitting (ZFS) parameters for Cr2+ ion in CdGa2S4 crystals. Firstly, the complete energy matrix including all spin states for a 3d 4 ion in tetrahedral D 2d symmetry is constructed according the double-group chain in the strong-field scheme. Then, by diagonalizing the complete energy of electron–electron interactions, the crystal field and the spin–orbit coupling for the Cr2+ (3d 4) ion in CdGa2S4 crystal, the fine structure levels and the spin-singlet contributions to ZFS parameters a, D and F are calculated. The results show that the spin-singlet contribution to D is negligible, but the contributions to a and F are very important. So, to obtain more accurate ZFS parameters for 3d 4 ions in the tetrahedral crystals, all spin states should be considered. 相似文献
997.
Antreas D. Athanassopoulos Emmanuel Thanassoulis 《The Journal of the Operational Research Society》1995,46(1):20-34
This paper discusses the practical usefulness of separating market efficiency from profitability when assessing the comparative performance of private sector organizational units. The market efficiency of a unit reflects its ability to attract custom. The paper shows how data envelopment analysis can be used to assess market efficiency and it illustrates the usefulness of this measure in managing the public houses of a brewery. 相似文献
998.
Michael Pidd 《The Journal of the Operational Research Society》1995,46(3):362-374
The three-phase approach provides a simple and robust way to develop discrete computer simulation programs. Object-orientation allows system developers to develop software which can be extended and also makes it impossible for important variables within a software system to be tampered with. This paper shows how the two approaches can be usefully combined and discusses the development of a simulation library, written in C++ and based on these ideas. Limitations of both approaches are also discussed. 相似文献
999.
A tractor-trailer problem, with full load, from the class of combined routeing and scheduling problems is described. Distinctive features of the problem are: movements must be carried out within certain time windows; subsets of movements are linked in the sense that they must be executed in a certain order; and different priorities are attached to different movements. A new bidirectional sequential constructive heuristic is developed for the solution of this problem. The method constructs routes and schedules for the available tractor fleet. The algorithm attempts to minimize the total time for all the movements by minimizing the time taken up by unproductive movements (so-called deadhead) and waiting time between movements. Some practical aspects of the implementation of the approach are discussed. 相似文献
1000.
Sara Maad 《Arkiv f?r Matematik》2003,41(1):105-114
We study a semilinear elliptic equation of the form
wheref is continuous, odd inu and satisfies some (subcritical) growth conditions. The domain Ω⊂RN is supposed to be an unbounded domain (N≥3). We introduce a class of domains, called strongly asymptotically contractive, and show that for such domains Ω, the equation
has infinitely many solutions. 相似文献