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51.
The design of a noncollinear acousto-optic tunable filter (AOTF) is commonly based on parallel tangent momentum-matching condition. Previous studies have either moving parts or modulation. These approaches would obviously decrease the accuracy of an acousto-optic tunable filter (AOTF) since it will be influenced by vibration or by an extended measurement time. In this paper, we introduce a novel noncollinear acousto-optic tunable filter division-of-amplitude photopolarimeter (DOAP). It is completely characterized by a wavelength-dependent 4 × 4 matrix that can be determined directly by calibration. The instrument has neither moving parts nor modulation. Besides, this system can acquire the image, spectral and polarization information of an object simultaneously. 相似文献
52.
K.?MatyjasekEmail author K.?Wolska S.?M.?Kaczmarek J.?Subocz L.?Ivleva 《Applied physics. B, Lasers and optics》2012,106(1):143-150
The influence of Ni doping on the ferroelectric and dielectric properties have been examined in Sr0.61Ba0.39Nb2O6 (SBN:61) relaxor crystals. The dopants introduced into SBN:61 crystals promote the switching process by reducing the value
of threshold nucleation field, and thus coercive field. We present real-time studies of domain nucleation and growth processes
in doped SBN:61 by the nematic liquid crystal (NLC) decoration technique. The broad phase transition and low-frequency dielectric
dispersion that are exhibited by doped SBN:61 samples have a strong link to the configuration of the ferroelectrics microdomains,
which in turn is strongly determined by Ni ions concentration. 相似文献
53.
近红外光谱(NIRS)广泛应用于生产过程分析与监测,常需事先建立定量校正或定性判别模型,并需在生产条件变化后调整模型,使用较复杂。本文从相异度和相似度两个对立互补的角度,提出自适应移动窗口标准差法和过程光谱相似度法,并以此为基础建立一种针对生产过程的无需校正模型的简易光谱在线监测方法。论文以中药柱层析过程为例,对监测过程作NIRS自适应移动窗口标准差趋势图和过程光谱相似度趋势图,并通过HPLC离线分析所得的多指标成分含量变化趋势图进行对比验证,发现可用于工艺状况实时监测,指导收集起点、终点、溶液相变点的判断,表明论文提出的方法合理可行。该方法亦可用于紫外/可见、红外、拉曼、荧光等光谱及色谱、质谱等其他过程分析技术。 相似文献
54.
分析了分光计中望远镜调节原理,归纳与总结了望远镜光轴、载物台都垂直于分光计中心轴的多种调节方法,有利于实验教学。 相似文献
55.
56.
为了减小常规L波段高功率微波测量接收天线的结构尺寸及增益,设计了一种基于轴向缝隙馈电的小型化同轴扩张型天线。通过理论分析和数值模拟,选择了较优的结构尺寸,得到天线的增益及方向图特性:在1.3~1.6 GHz范围内,增益从-2.0 dBi变化至0.8 dBi;天线最大辐射方向在物理结构轴向。基于矢量网络分析仪E8362B的天线特性测量结果与数值计算结果基本一致:工作频率从1.3~1.6 GHz变化时,增益从-2.3 dBi变化至1.2 dBi;E面方向图主瓣宽度大于60,轴向轴比大于35 dB,结果表明设计的天线能够满足L波段高功率微波测量天线低增益小型化要求。 相似文献
57.
长周期光纤光栅折射率特性仿真的新方法 总被引:1,自引:1,他引:0
基于长周期光纤光栅的模式耦合机理,提出一种快速模拟长周期光纤光栅折射率特性的方法。该方法在计算包层模式的有效折射率时分开计算,在环境折射率小于包层折射率时采用二分法和分步搜索法结合计算包层模式的有效折射率,在环境折射率大于包层折射率时采用Nelder-Mead加分步搜索法求解包层模式的有效折射率。在应用谐振波长的决定式求解与环境折射率的匹配的谐振波长时,采用变区间应用二分法求解而不是传统的逐步搜索法求解谐振波长。数值结果与实验结果做了对比,两者基本一致。实践证明,该方法方便快捷,比一般的方法速度提高7倍以上。 相似文献
58.
59.
We study the formation of multi-armed spirals and multi-pairs antispirals in spatial rock–paper–scissors games with mobile individuals. We discover a set of seed distributions of species, which is able to produce multi-armed spirals and multi-pairs antispirals with a finite number of arms and pairs based on stochastic processes. The joint spiral waves are also predicted by a theoretical model based on partial differential equations associated with specific initial conditions. The spatial entropy of patterns is introduced to differentiate the multi-armed spirals and multi-pairs antispirals. For the given mobility, the spatial entropy of multi-armed spirals is higher than that of single armed spirals. The stability of the waves is explored with respect to individual mobility. Particularly, we find that both two armed spirals and one pair antispirals transform to the single armed spirals. Furthermore, multi-armed spirals and multi-pairs antispirals are relatively stable for intermediate mobility. The joint spirals with lower numbers of arms and pairs are relatively more stable than those with higher numbers of arms and pairs. In addition, comparing to large amount of previous work, we employ the no flux boundary conditions which enables quantitative studies of pattern formation and stability in the system of stochastic interactions in the absence of excitable media. 相似文献
60.
Adaptive synchronization of chaos in permanent magnet synchronous motors based on passivity theory 下载免费PDF全文
An adaptive synchronization control method is proposed for chaotic permanent magnet synchronous motors based on the property of a passive system. We prove that the controller makes the synchronization error system between the driving and the response systems not only passive but also asymptotically stable. The simulation results show that the proposed method is effective and robust against uncertainties in the systemic parameters. 相似文献