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491.
Gerhard A. Koepf H. R. Fetterman Nelson McAvoy 《International Journal of Infrared and Millimeter Waves》1980,1(4):597-607
A submillimeter laser with off-axis pump beam injection is described. This design concept achieves complete isolation of the pump laser with respect to the pump radiation reflected from the smm resonator. Active line independent stabilization of the pump laser is obtained by the use of an external tunable etalon as a frequency reference. The smm output power is constant to within 4% over periods of hours. Mean frequency drifts of less than 2 parts in 108 per minute were measured by mixing with very high harmonics of an X-band synthesizer in a planar Schottky diode.Supported in part by NSF 相似文献
492.
Markus Berndt Jérôme Breil Stéphane Galera Milan Kucharik Pierre-Henri Maire Mikhail Shashkov 《Journal of computational physics》2011,230(17):6664-6687
We present a new hybrid conservative remapping algorithm for multimaterial Arbitrary Lagrangian–Eulerian (ALE) methods. The hybrid remapping is performed in two steps. In the first step, only nodes of the grid that lie inside subdomains occupied by single materials are moved. At this stage, computationally cheap swept-region remapping is used. In the second step, nodes that are vertices of mixed cells (cells containing several materials) and vertices of some cells in a buffer zone around mixed cells are moved. At this stage, intersection-based remapping is used. The hybrid algorithm results in computational expense that lies between swept-region and intersection-based remapping We demonstrate the performance of our new method for both structured and unstructured polygonal grids in two dimensions, as well as for cell-centered and staggered discretizations. 相似文献
493.
对于守恒型扩散方程,研究其二阶时间精度非线性全隐有限差分离散格式的性质,证明了其解的存在唯一性.研究了二阶时间精度的Picard-Newton迭代格式,证明了迭代解对原问题真解的二阶时间和空间收敛性,以及对非线性离散解的二次收敛速度,实现了非线性问题的快速求解.本文中方法也适用于一阶时间精度格式的分析,并可推广至对流扩散问题.数值实验验证了二阶时间精度Picard-Newton迭代格式的高精度和高效率. 相似文献
494.
A KAM Theorem for Reversible Systems of Infinite Dimension 总被引:1,自引:0,他引:1
Shun Qing CHEN Xiao Ping YUAN 《数学学报(英文版)》2007,23(10):1777-1796
For reversible systems of infinite dimension we prove an infinitely dimensional KAM theorem with an application to the network of weakly coupled oscillators of friction. The KAM theorem shows that there are many invariant tori of infinite dimension, and thus many almost periodic solutions, for the reversible systems. 相似文献
495.
提出一种基于分布反馈光注入锁定效应的可调谐光电振荡器,其环路主要由马赫曾德尔调制器、光电探测器、环形器、分布反馈激光器和射频放大器顺接而成,分布反馈激光器是系统关键器件,通过分布反馈激光器光注入锁定效应,分布反馈腔在光域实现了微波光子滤波器功能,无需传统光电振荡器必须的射频带通滤波器.同时,由于分布反馈激光器注入锁定提高了环路Q值,因此系统可采用短环路结构,从而降低了光纤因温度敏感对微波信号稳定性的影响并减小了整个系统的尺寸.另外,通过调节注入光波长和功率可改变该微波光子滤波器的中心频率,从而可实现系统的可调谐性.理论分析了该光电振荡器的原理和微波光子滤波器的调谐性,在此基础上开展了实验验证.结果表明该光电振荡器能够产生18.7~21.6 GHz的可调微波信号,在1 kHz频偏处的相位噪声为-90 dBc/Hz. 相似文献
496.
The perturbation-incremental method is extended to determine thebifurcations and limit cycles of strongly nonlinear autonomousoscillators with many degrees of freedom. Coupled van der Poloscillators and coupled Rayleigh oscillators are taken as numericalexamples. Limit cycles of the oscillators can be calculated to anydesired degree of accuracy. The stabilities of limit cycles are alsodiscussed. 相似文献
497.
498.
Q. Y. Wang Q. S. Lu G. R. Chen 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):255-261
The collective behaviour of a square-lattice
Hodgkin-Huxley neural network model with white noise is
investigated by numerical methods. It is found that for an
intermediate value of noise the Hodgkin-Huxley neurons in the
square lattice exhibit an ordered circular structure. However, as
the noise level increases, the ordered circular structures are
distorted, and eventually totally destroyed. Thereby, the
constructive role of appropriately pronounced random perturbations
in the studied network is revealed. Furthermore, it is shown that
as the diffusive coefficient increases, the typical width of the
spatial waves also increases accordingly, which results in a
decrease of the number of cycles by a given size of the spatial
grid. More interestingly, it is observed that the spatio-temporal
coherence resonance is enhanced as the diffusive coefficient is
increased. Finally, the dependence of the typical width and the
average period of the firing rate function on the diffusive
coefficient is studied. Results presented in this paper should
prove valuable for the understanding of information processing of
neural systems in the presence of noise. 相似文献
499.
The effects of pump phase modulation on noise characteristics of
fiber optical parametric amplifiers
M. Gao C. Jiang W. Hu J. Wang H. Ren 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):431-436
This paper investigates the effects of pump phase
modulation (PM) on the noise characteristics of fiber optical parametric
amplifiers (FOPAs) theoretically. The results show that the effect of the
pump PM on the noise of FOPAs can be diminished by adjusting the structural
parameters of amplifiers properly. The parameters of the pump phase
modulation are optimized with several methods to reduce the noise of FOPAs. 相似文献
500.
A model of two-dimensional coupled complex Ginzburg-Landau oscillators driven by a rectificative feedbackcontroller is used to study controlling spatiotemporal chaos without gradient force items. By properly selecting the signalinjecting position with considering the maximum gap between signals and targets, and adjusting the control time interval,we have finally obtained the efficient chaos control via numerical simulations. 相似文献