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991.
The principle and experimental results of the open microwave resonant cavity measurement system were introduced. The models were steel ball models and the ball models coated with copper. The diameter of the models was 10mm . The models were launched in ballistic range. The model velocity was 5.44 km .s-1. The wake electron density of the models was obtained. The experimental results presents that the response time of the open microwave resonant cavity measurement system was quicker than 1ms. The results showed the wake electron density ranged from 109cm -3 to 1011cm -3 could be achieved. 相似文献
992.
Numerical and experimental study on coherent beam combining of fibre amplifiers using simulated annealing algorithm 下载免费PDF全文
We present the numerical and experimental study on
the coherent beam combining of fibre amplifiers by means of simulated
annealing (SA) algorithm. The feasibility is validated by the Monte
Carlo simulation of correcting static phase distortion using SA
algorithm. The performance of SA algorithm under time-varying phase
noise is numerically studied by dynamic simulation. It is revealed
that the influence of phase noise on the performance of SA algorithm
gets stronger with an increase in amplitude or frequency of phase
noise; and the laser array that contains more lasers will be more
affected from phase noise. The performance of SA
algorithm for coherent beam combining is also compared with a widely
used stochastic optimization algorithm, i.e., the stochastic
parallel gradient descent (SPGD) algorithm. In a proof-of-concept
experiment we demonstrate the coherent beam combining of two 1083~nm
fibre amplifiers with a total output power of 12~W and 93%
combining efficiency. The contrast of the far-field coherently
combined beam profiles is calculated to be as high as 95%. 相似文献
993.
以铋、钆的硝酸盐等制备前驱溶胶体系,用CSD法在SrTiO3(100)基底上制备出c轴织构良好的可作为涂层导体缓冲层的GdBiO3(GBO)薄膜。首先利用差热分析的结果对GBO薄膜分解过程的吸、放热情况进行了研究,确定了较为适当的有机物分解工艺。在此基础上研究了不同外延成相热处理温度对GBO薄膜生长的影响,并对较高温度处理后样品产生裂纹的原因进行了初步分析。GBO薄膜的相组成和微结构利用XRD和SEM进行分析。研究结果表明,在Ar气氛中适宜于GBO薄膜生长的最佳温度在770℃度附近,在此条件下可以制备出表面平整致密的GBO薄膜。 相似文献
994.
995.
轴向隐失波激励的回音壁模式光纤激光器 总被引:4,自引:1,他引:3
采用轴向隐失波激励增益的方式,使激光增益区域局限在光纤回音壁模式的模场区域内,显著地降低了回音壁模式光纤激光辐射的抽运阈值,由此形成一种低阈值的回音壁模式光纤激光器.在微焦耳量级的低抽运能量条件下,用回音壁模式光纤激光器研究了激光染料的浓度效应.实验结果表明,随着激光染料浓度的增加,回音壁模式激光辐射的波长向长波方向移动,激光波长范围变宽.用回音壁模式染料激光的四能级模型得到激光上能级和所有能级上的分子数比值γ(λ)曲线后,很好地解释了实验结果.低抽运阈值的回音壁模式光纤激光器,为研究液体激光现象提供了极为便利的手段. 相似文献
996.
We address the effect of the truncation parameter and spherical aberration (SA) on the singularity transformation and spectral behavior of the polychromatic Gaussian beams focused by an aperture lens with SA in detail. The numerical simulation results, based on the derived equations of the intensity and the spectral density, are given. It is found that the axial singularities vanished with the change of the truncated parameter. The intensity and drastic spectral change fade away with an annihilation process of the phase singularities, and the drastic spectral change does not disappear immediately at the moment the phase singularity annihilates. The singularities in the focal region will redistribute with the increment of SA coefficient, some singularities will vanish, some will spilt into two new singularities, and other off-axial singularities will appear and split into two new singularities as well. When SA coefficient changed, we can find that the axial singularities disappear as well with the decreasing value of truncation parameter. These new splitted singularities due to the change of SA coefficient will converge into one singularity again and disappear gradually. 相似文献
997.
The Mott relation between the electrical and thermoelectric transport coefficients normally holds for phenomena involving scattering. However, the anomalous Hall effect (AHE) in ferromagnets may arise from intrinsic spin-orbit interaction. In this work, we have simultaneously measured AHE and the anomalous Nernst effect (ANE) in Ga1-xMnxAs ferromagnetic semiconductor films, and observed an exceptionally large ANE at zero magnetic field. We further show that AHE and ANE share a common origin and demonstrate the validity of the Mott relation for the anomalous transport phenomena. 相似文献
998.
Shengli Pu Tao Geng Xianfeng Chen Xianglong Zeng Ming Liu Ziyun Di 《Journal of magnetism and magnetic materials》2008
The model of tunable superparamagnetic photonic crystals self-assembled in colloidal magnetic fluids under externally applied magnetic fields is established. The mechanisms, which are in charge of the tunability of the band gaps with magnetic fields are clarified. The band structures of the triangularly-arrayed two-dimensional photonic crystals with limited heights of magnetic columns are calculated with the experimental data of structures and refractive indices in the literatures. The field-dependent properties of the first band gaps are gained for the z-odd and z-even modes, respectively. Simulation results indicate that the mid frequencies of the first band gaps of the z-odd modes can be easily tuned by the external magnetic fields, while those of the z-even modes bear relatively weak dependence on the external magnetic fields. Simultaneously, the first band gaps of both kinds of modes become wide along with the increase of the magnetic fields. The results presented in this work give a guideline for realizing the tunable photonic crystals with magnetically colloidal materials and magnetic stimuli. 相似文献
999.
1000.
Jianming Lin Jihuai Wu Zhengfang Yang Minli Pu 《Macromolecular rapid communications》2001,22(6):422-424
A novel poly(acrylic acid)/mica superabsorbent composite was synthesized by graft polymerization reaction between partially neutralized acrylic acid and ultrafine mica mineral powder. The water absorbency of the composite is higher than 1 100 g H2O/g. The influence of the neutralization degree of acrylic acid, as well as of the amounts of mica and crosslinker on the absorbing properties are discussed in this paper. 相似文献