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981.
采用对称约简的分析方法,得出了变系数Ginzburg-Landau方程的抛物渐近自相似脉冲解析解的一般表达式.给出了二阶色散系数纵向双曲型变化和纵向指数型变化的色散渐减光纤中自相似脉冲的振幅、啁啾以及脉冲宽度的具体形式,并与数值解进行了对比,其结果符合得很好.从而证实了稀土元素掺杂的色散渐减光纤中,在增益色散因子的影响下,脉冲的演化具有抛物型自相似特性. 相似文献
982.
983.
基于经典小波变换的布里渊光时域反射计光信号处理 总被引:1,自引:0,他引:1
布里渊光时域反射计结构的布里渊散射分布式光纤传感器检测的是自发散射光,信号非常微弱,而且频带在几十兆赫兹以上,难以应用普通相干解调方法。针对传感散射光信号特点,提出基于经典(Morlet)小波变换的光相干检测方法。首先采用微波电光调制产生频移参考光和自发布里渊散射光进行相干检测,再应用经典小波变换进行散射光信号的幅度解调,得到信噪比改善的布里渊散射传感光信号。给出了数值模拟和实验数据处理结果,表明经典小波变换能较好地处理布里渊光时域反射计检测信号。并和基于希尔伯特(Hilbert)变换的传感信号处理方法进行了对比,发现此方法优于基于希尔伯特变换的信号处理。 相似文献
984.
985.
986.
With some reviews on the investigations on the schemes for quantum state transfer based on spin systems, we discuss the quantum
dynamics of magnetically-controlled networks for Bloch electrons. The networks are constructed by connecting several tight-binding
chains with uniform nearest-neighbor hopping integrals. The external magnetic field and the connecting hopping integrals can
be used to control the intrinsic properties of the networks. For several typical networks, rigorous results are shown for
some specific values of external magnetic field and the connecting hopping integrals: a complicated network can be reduced
into a virtual network, which is a direct sum of some independent chains with uniform nearest-neighbor hopping integrals.
These reductions are due to the fermionic statistics and the Aharonov-Bohm effects. In application, we study the quantum dynamics
of wave packet motion of Bloch electrons in such networks. For various geometrical configurations, these networks can function
as some optical devices, such as beam splitters, switches and interferometers. When the Bloch electrons as Gaussian wave packets
input these devices, various quantum coherence phenomena can be observed, e.g., the perfect quantum state transfer without
reflection in a Y-shaped beam, the multi-mode entanglers of electron wave by star-shaped network, magnetically controlled
switches, and Bloch electron interferometer with the lattice Aharonov-Bohm effects. With these quantum coherent features,
the networks are expected to be used as quantum information processors for the fermion system based on the possible engineered
solid state systems, such as the array of quantum dots that can be implemented experimentally.
相似文献
987.
Bulk mechanical alloying (BMA) followed by hot pressing (HP) was used to prepare Mg2Si0.6Ge0.4 thermoelectric material with high densification. Starting from the elemental power mixture, the Mg2Si0.6Ge0.4 solid solution was solid‐state synthesized via BMA. In fact, the peaks for the cubic‐structured Mg2Si0.6Ge0.4 solid solution phase were detected after 300 cycles in BMA. The single phase of Mg2Si0.6Ge0.4 was synthesized at 600 cycles in BMA. Mg2Si0.6Ge0.4 showed p‐type semiconduction without doping. Effects of hot pressing conditions on thermoelectric properties were investigated. With increasing hot pressing temperature from 673 to 773 K and pressure from 500 MPa to 1 GPa, the electrical conductivity increased and the Seebeck coefficient decreased. The maximum figure of merit was obtained with the processing parameter of 600 cycles BMA and hot pressing at 773 K, 1 GPa for 1 h. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
988.
989.
Hong-Qiang Song Yong Wang Shi-Shen Yan Liang-Mo Mei Ze Zhang 《Journal of magnetism and magnetic materials》2007
TiO2:Co thin films of high Co concentration were investigated by the high resolution transmission electron microscopy, physical property measurement system and energy dispersive X-ray. The as-deposited films are amorphous magnetic semiconductors and we did not find any Co metal particles in them. The electronic transport process in the low-temperature range below 80 K could be described by the spin-dependent variable-range-hopping process. However, after the samples were annealed at 300 °C, large amounts of Co metal particles were observed to connect each other and the films show a metallic behavior. The origin of ferromagnetism of the thin films is also discussed. 相似文献
990.
Zhi Yan Zhitang Song Hongxuan Ren Xiaoyuan Zhou Yu Wang Lihui Lai 《Applied Surface Science》2007,253(24):9372-9380
Zinc oxide based film bulk acoustic resonator as mass sensor was fabricated by multi-target magnetron sputtering under optimized deposition condition. Each layer of the device was well crystallized and highly textural observed by transmission electron microscopy and X-ray diffraction measurement. Through piezoelectric test, the device vibrated with significant distance. The influence of top electrode on resonant frequency and the bio-specimen of mass loading effect were investigated. Data show that the device has qualified properties as mass biosensor, with a resonant frequency of 3-4 GHz and a high sensitivity of 8-10 kHz cm2/ng. 相似文献