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51.
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We propose an efficient scheme for optimizing the optical memory of a sequence of signal light pulses in a system of ultracold atoms in ∧ configuration.The memory procedure consists of write-in,storage,and retrieval phases.By applying a weak microwave field in the storage stage,additional phase-dependent terms are included,and the contrast of the output signal pulses can be dynamically controlled(enhanced or suppressed) through manipulating the relative phase φ between optical and microwave fields.Our numerical analysis shows that the contrast is enhanced to the most extent when φ = 1.5π.In addition,the contrast is in proportion to the Rabi frequency of the microwave field with a certain relative phase. 相似文献
53.
One-dimensional photonic crystal structures for multiple channeled
filtering and polarization selective filtering in the terahertz
(THz) range are studied theoretically. The design of aperiodic photonic
quantum-well (APQW) structures for multiple channeled filtering and
different polarization filtering at arbitrary preassigned
frequencies are achieved by using the simulated annealing algorithm
with a special merit function. The parameters of these filters can
be expediently controlled and the transmission characters are
polarization dependent. Numerical simulations show that the designed
APQWs can meet the desired specification well. 相似文献
54.
In this paper multiple delay feedback control (MDFC) with different
and independent delay times is shown to be an efficient method for
stabilizing fixed points in finite-dimensional dynamical systems.
Whether MDFC can be applied to infinite-dimensional systems has been
an open question. In this paper we find that for infinite-dimensional
systems modelled by delay differential equations, MDFC works well for
stabilizing (unstable) steady states in long-, moderate- and
short-time delay regions, in particular for the hyperchaotic case. 相似文献
56.
For the first time, we report on projective synchronization between two time delay chaotic systems with single time delays. It overcomes some limitations of the previous work, where projective synchronization has been investigated only in finite-dimensional chaotic systems, so we can achieve projective synchronization in infinitedimensional chaotic systems. We give a general method with which we can achieve projective synchronization in time-delayed chaotic systems. The method is illustrated using the famous delay-differential equations related to optical bistability. Numerical simulations fully support the analytical approach. 相似文献
57.
建立了快速滤过型净化(m-PFC)结合气相色谱-串联质谱(GC-MS/MS)测定茶叶中10种拟除虫菊酯类农药残留的方法。比较了采用不同提取溶剂(乙腈、丙酮和乙酸乙酯)和不同提取方式(不加水浸泡和加水浸泡)时10种农药的提取效率;比较了2种QuEChERS净化管和m-PFC柱对茶叶提取液的净化效果和农药残留的回收率。结果表明,茶叶样品不加水浸泡,用乙腈提取效果最好;m-PFC柱对茶叶提取液净化效果良好,而且能保证较高的农药回收率。10种拟除虫菊酯农药在相应的范围内有良好的线性关系,相关系数(R2)大于0.9980;10种农药在4个水平添加下的回收率为87.5%~111.3%,RSD为2.1%~8.9%。方法的检出限为0.001~0.015 mg/kg,定量限为0.003~0.05 mg/kg。利用该方法检测市售50例茶叶样品中10种拟除虫菊酯农药的残留,检出率为48%,但农药残留量均在国家标准限量值以下。与传统QuEChERS法和固相萃取法相比,该方法具有操作简单、准确度和精密度良好等优点,为多种拟除虫菊酯类农药在茶叶中的残留测定提供了快速检测的新方法。 相似文献
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沸腾回流强迫水解法制备均分散α—Fe2O3超微粒水溶胶 总被引:10,自引:0,他引:10
Matijevic等曾报道在密闭静态环境下强迫水解酸化的铁盐溶液制备出几种形状单一的微米或亚微米级的均匀α-Fe_2O_3或β-FeOOH胶体粒子。类似的工作国内亦有报道。如粒子尺寸减小到纳米量级,则体系兼有表面效应、体积效应和特殊的光学性质。我们尝试用强迫水解法制备粒径几十纳米的球形或立方形的α-Fe_2O_3均分散胶体粒子,结果获得成功。 相似文献