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51.
复合六边形空气孔格点光子晶体光纤的色散特性分析 总被引:1,自引:0,他引:1
提出了一种复合六边形空气孔格点光子晶体光纤,其包层是由两种不同大小的空气孔组合而构成的。利用带有良匹配层(APML)吸收边界的全矢量频域有限差分法(FDFD)对其色散特性进行了数值分析。结果表明,通过调节包层中两种不同尺寸的空气孔的大小以及孔间距这三个参量,可以得到不同水平的平坦色散曲线,甚至超低超平坦的色散曲线。在孔间距Λ取2.1μm,小尺寸空气孔直径取0.5μm,大尺寸空气孔直径取0.8μm的条件下,在1.48~1.78μm的波长范围内得到了0±0.545 ps/(km.nm)的色散。 相似文献
52.
Let be a polynomial semigroup containing an element with degree at least 2 with the semigroup operation being functional composition. We prove that is nearly abelian if and only if the smallest completely invariant closed subset of the Riemann sphere is not equal to the Riemann sphere. We also give a positive answer to Conjecture 7.1 in Hinkkanen and Martin's paper on the dynamics of semigroups of rational functions.
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J. Kenedy Martins 《Bulletin of the Brazilian Mathematical Society》2001,32(1):83-105
The invariants needed to decide when a pair of hypersurfaces ofS
6 orCP
n
are respectivelyG
2-congruent or holomorpic congruent are determined and this result is used to characterize the hypersurfaces of these spaces whose Hopf vector fields are also Killing fields. 相似文献
56.
基于近圆轨道卫星的特点,通过理论公式推导,确定卫星星下点轨道,建立近圆轨道卫星过顶时间预报的数学模型.首先依据观察站确定卫星进出观察站接收圈时星下点的经纬度,然后根据该点经纬度与卫星倾斜角推求卫星的升交点或者降交点,最后从升交点或者降交点出发外推不超过1/4周期,两者合并得到整个周期的卫星轨迹推导公式.将模型应用于已知和未知卫星轨道根数的实际军事行动避空侦察中去,与实际检测情况相比误差较小、吻合度较高,说明模型有较好的工程应用价值. 相似文献
57.
We relate the equianalytic and the equisingular deformations of a reduced complex plane curve to the Jacobian syzygies of its defining equation. Several examples and conjectures involving rational cuspidal curves are discussed. 相似文献
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One of the unresolved issues on Saint-Venant's principle concerns the energy decay estimates established in the literature for the traction boundary-value problem of three-dimensional linear isotropic elastostatics for a cylinder. For the semi-infinite cylinder with traction-free lateral surface and self-equilibrated loads at the near end, it has been shown that the stresses decay exponentially from the end and results were obtained for the estimated decay rate, which is a lower bound for the exact decay rate. These results are, however, generally conservative in that they underestimate the exact decay rate. Another shortcoming, which motivated the present investigation, is that the estimated decay rates tend to zero as the Poisson's ratio tends to the value 1/2. Thus for the limiting case of an incompressible material, these methods fail to establish exponential decay. The purpose of the present paper is to remedy this defect. In particular, an exponential decay estimate is established with estimated decay rate independent of Poisson's ratio. Thus, in particular, the results here hold in the incompressible limit as 1/2. An alternative treatment directly for the incompressible case has been given recently. It should be noted that the stresses in the three-dimensional traction boundary-value problem do depend on Poisson's ratio and that stress decay estimates for the cylinder problem with estimated decay rates dependent on are, in fact, to be expected. However, in the absence of such results that do not deteriorate as 1/2, we obtain here an estimated decay rate that is independent of . 相似文献
60.
IntroductionAsanimportantnumericalmethod ,BoundaryElementMethod (BEM)hasbeenappliedinmanyareas[1].However,theBEMhasthedifficultiesofcalculatingsingularintegralsatnodesonboundaryoratinteriorpointsveryclosetotheboundary .TheaccuracyoftheBEMdependsontheprecisionofthecalculatedvaluesofthesingularintegrals,toagreatdegree.Manyresearchersdevotethemselvestothetreatmentofthesingularintegrals[2~3],whicharereviewedindetailbyRef.[4] .Ageneralregularizationalgorithmofevaluatingthephysicalquantitiesa… 相似文献