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971.
低重复率的Ti:Al2O3飞秒激光放大器研究 总被引:5,自引:1,他引:4
本文报道了重复频率为10Hz的Ti:Al2O3飞秒激光放大器的研究.基于脉冲啁啾放大技术和采用再生/多通放大装置,得到了能量为8mJ的放大光脉冲,在该放大系统中,激光脉冲获M净增益约8×107. 相似文献
972.
973.
An epidemic model with a constant removal rate of infective individuals is proposed to understand the effect of limited resources for treatment of infectives on the disease spread. It is found that it is unnecessary to take such a large treatment capacity that endemic equilibria disappear to eradicate the disease. It is shown that the outcome of disease spread may depend on the position of the initial states for certain range of parameters. It is also shown that the model undergoes a sequence of bifurcations including saddle-node bifurcation, subcritical Hopf bifurcation, and homoclinic bifurcation. 相似文献
974.
Enguo Gu Jiong Ruan Zhenxun Huang 《Communications in Nonlinear Science & Numerical Simulation》1998,3(4):242-247
In this paper, a problem of stabilizing a period-T orbit in discrete chaotic m degree polynomial dynamical systems is studied. The aim is to present a new method for determining the neighborhood of a period-T point in which the system remains stable when subjected to a linear feedback control. A theorem on the existence of neighborhood is rigorously proved using idea from functional analysis and polar coordinate transformation. The ways of implementing the obtained theorem in the Hénon map are proposed. The validity of this method is shown by numerical simulation. 相似文献
975.
For any complete noncompact Kähler manifold with nonnegative and bounded holomorphic bisectional curvature, we provide the necessary and sufficient condition for the immortal solution to the Ricci flow. 相似文献
976.
General formulae for the transient evolution of the susceptibility (absorption) induced by the quantum interference effect in a four-level N-type EIT medium is presented. The influence of the signal light on the transient susceptibility for the probe beam is studied for two typical cases when the strength of the coupling beam is much greater or less than that of the signal field. An interesting level reciprocity relationship between these two cases is found. 相似文献
977.
978.
Optimization of Multilevel Investments Using Dynamic Programming Based on Fuzzy Cash Flows 总被引:1,自引:0,他引:1
Cengiz Kahraman Da Ruan Cafer Erhan Bozdag 《Fuzzy Optimization and Decision Making》2003,2(2):101-122
Dynamic programming is applicable to any situation where items from several groups must be combined to form an entity, such as a composite investment or a transportation route connecting several districts. The most desirable entity is constructed in stages by forming sub-entities of progressively larger size. At each stage of the development, the sub-entities that are candidates for inclusion in the most desirable entity are retained, and all other sub-entities are discarded. In deterministic dynamic programming, a specification of the current state and current decision is enough to tell us with certainty the new state and costs during the current stage. In many practical problems, these factors may not be known with certainty, even if the current state and decision are known. In this paper, the dynamic programming is applied to the situation where each investment in the set has the following characteristics: the amount to be invested has several possible values, and the rate of return varies with the amount invested. Each sum that may be invested represents a distinct level of investment, and the investment therefore has multiple levels. A fuzzy present worth based dynamic programming approach is used. A numeric example for a multilevel investment with fuzzy geometric cash flows is given. A computer software named FUZDYN is developed for various problems such as alternatives having different lives, different uniform cash flows, and different ranking methods. 相似文献
979.
In this paper, a new type of circular-shaped microshield and conductor-backed coplanar waveguide is proposed. Analytic closed-form
expressions for characteristic impedance and effective dielectric constant for the new line are obtained using conformal mapping
method under the assumption of pure-TEM propagation and zero dispersion. The new waveguide proposed by this paper can reduce
radiation to much less than the conventional coplanar waveguide and microstrip, and can reduce the current concentration at
both the edges of the strip conductor. 相似文献
980.
光子晶体缺陷模的带宽与品质因子研究 总被引:22,自引:11,他引:11
利用光学传输矩阵法研究了结构参量对缺陷态光子晶体的缺陷模带宽和品质因子的影响.研究发现,当缺陷介质层厚度h0的值较小时,缺陷模的带宽很小且基本保持不变;当h0较大时,缺陷模的带宽随h0的增加而快速增加.另外发现,缺陷模的品质因子在某个h0处取最大值.但是总体上看,h0较小时的品质因子要远大于h0较大时的品质因子.此外,缺陷模的品质因子随光子晶体的周期数增加而急剧增加约4.788倍,而带宽则随周期数的增加而急剧减少约4.788倍.当周期数为13时就可以获得109以上的品质因子值和小于10-9的相对带宽值. 相似文献