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961.
We investigate numerically the effects of higher-order space-charge field on the self-deflection of bright photovoltaic spatial solitons in two-photon photovoltaic photorefractive crystals under steady-state conditions. The expression for an induced space-charge electric field, including higher-order space-charge field terms is obtained. The dynamical evolution equation is built in which the effects that arise from these higher-order terms are considered. Numerical results indicate that bright photovoltaic solitons can bend towards both the same direction as the crystal's c-axis and the opposite direction, respectively. Specifically, self-deflection cannot occur for bright photovoltaic solitons if the strength of the photovoltaic field and the intensity of the input beam are appropriately selected. Relevant examples are provided. 相似文献
962.
Zhenghong He Zhicheng Ye Qingyu Cui Jiliang Zhu Hongyue Gao Yuye Ling Hongqing Cui Jiangang Lu Xiaojun Guo Yikai Su 《Optics Communications》2011,284(16-17):4022-4027
We study one-dimensional photonic crystals made of cholesteric liquid crystals with sandwiched isotropic defect layers. Based on the Berreman Fast 4 × 4 matrix method, the dispersion relation of one-dimensional photonic crystals is calculated and the corresponding reflection chromaticity is obtained. It is found that the color shift could be controlled by adjusting the thickness and refractive index of the isotropic defect layers. Compared with conventional structures, the reflection chromaticity of this structure is insensitive to the incident angle, if the thickness ratio of the cholesteric liquid crystals to that of the isotropic defect layers and the refractive index of periodical isotropic defect layers are properly set. Furthermore, the common forbidden bands for both left and right circular polarizations can be obtained, and we also take the wavelength-dependent refractive indices into consideration and obtain the reflected light chromaticity with the incident angle increasing. The proposed device can be used as a reflective color filter in the display industry. 相似文献
963.
A linearized tensor renormalization group algorithm is developed to calculate the thermodynamic properties of low-dimensional quantum lattice models. This new approach employs the infinite time-evolving block decimation technique, and allows for treating directly the transfer-matrix tensor network that makes it more scalable. To illustrate the performance, the thermodynamic quantities of the quantum XY spin chain as well as the Heisenberg antiferromagnet on a honeycomb lattice are calculated by the linearized tensor renormalization group method, showing the pronounced precision and high efficiency. 相似文献
964.
Uniaxial systems often form labyrinthine domains that exhibit short-range order but are macroscopically isotropic and would not be expected to exhibit precise symmetries. However, their underlying frustration results in a multitude of metastable configurations of comparable energy, and driving such a system externally might lead to pattern formation. We find that soft x-ray speckle diffraction patterns of the labyrinthine domains in CoPd/IrMn heterostructures reveal a diverse array of hidden rotational symmetries about the magnetization axis, thereby suggesting an unusual form of emergent order in an otherwise disordered system. These symmetries depend on applied magnetic field, magnetization history, and scattering wave vector. Maps of rotational symmetry exhibit intriguing structures that can be controlled by manipulating the applied magnetic field in concert with the exchange bias condition. 相似文献
965.
966.
为评定光斑环围参量(包括环围功率和环围尺寸)阵列测试法的测量不确定度,给出了环围参量一般形式的定义和连续形式的计算表达式,归纳并比较了阵列测试法下光斑环围参量的3种常用计算方法,即近似环围功率法、准确环围功率法和等效环围尺寸法,给出了零阶近似下环围参量离散形式的计算表达式。根据不确定度传递律,推导了基于等效环围尺寸法的环围参量测量不确定度的一般表达式,讨论了常见简化条件下的环围参量测量不确定度表达式。建立了光斑环围参量计算及其不确定度评定的一套较完整的方法。以强度为高斯分布的光斑为例,得到了简化条件下的环围参量测量不确定度的解析表达式,并用数值模拟法验证了其正确性。 相似文献
967.
半导体制冷电脑CPU恒温散热研究 总被引:1,自引:1,他引:0
用风冷的方法给CPU降温存在着降温效率低、反应速度慢、风扇的机械转动可靠性差、噪音大等弊病.因此,这里设计了一种用半导体制冷降温的装置来提高CPU的散热效率.它用温度传感器检测电脑CPU温度,当CPU温度超过设定温度的时侯,控制电路供电使半导体制冷块制冷,使CPU温度保持恒定.为防止冷凝结露,采用绝热材料密封导热铜板及... 相似文献
968.
969.
S. Sambasivam D. Paul Joseph Jung Hyun Jeong Byung Chun Choi Kwon Taek Lim Sang Su Kim Tae Kwon Song 《Journal of nanoparticle research》2011,13(10):4623-4630
Diluted magnetic semiconductor (DMS) nanoparticles of Sn1−x
Er
x
O2 (x = 0.0, 0.02, 0.04, and 0.1) were prepared by sol–gel method. The X-ray diffraction patterns showed SnO2 rutile structure for all samples with no impurity peaks. The decrease in crystallite size with Er concentration was confirmed
from TEM measurements (from 12 to 4 nm). The UV–Visible absorption spectra of Er-doped SnO2 nanoparticles showed blue shift in band gap compared to undoped SnO2. The electron spin resonance analysis of Er-doped SnO2 nanoparticles indicate Er3+ in a rutile lattice and also decrease in intensity with Er concentration above x = 0.02. Temperature-dependent magnetization studies and the inverse susceptibility curves indicated increased antiferromagnetic
interaction with Er concentration. 相似文献
970.
Lin Su Chao Wang Yong-hao Yu Yong-ying Ren Ke-liang Xie Guo-lin Wang 《BMC neuroscience》2011,12(1):120