A strain-induced birefringent double-clad fiber Bragg grating

A strain-induced birefringence double-clad (DC) fiber Bragg grating (FBG) is proposed and demonstrated.The grating is fabricated in the core of rectangular inner cladding double clad fiber by using phase mask method. By applying lateral strain on the grating, the birefringence is induced. In order to detect the birefringent effect of the grating, we use it as the output mirror of a laser. When lateral strain is applied,the grating becomes birefringent. Therefore, one reflection peak of double-clad fiber Bragg grating becomes two peaks and the laser also lases in two wavelengths. The wavelength spacing of the laser can be tuned from 0 to 0.8 nm. The absolute wavelengths for the two polarizations can be tuned 1.2 and 2.0 nm,respectively.     

拉盖尔高斯径向偏振光高数值孔径聚焦特性

光波在高数值孔径聚焦下焦点区域光强分布呈现出的特殊性质已经被应用到光学显微成像、微粒控制、光存储等领域中.本文基于矢量Deby衍射理论研究了TM01模拉盖尔高斯径向偏振光经高数值孔径聚焦下焦点区域光强分布.通过调节入瞳半径与光束束腰之比,发现拉盖尔高斯径向偏振光光斑由明亮尺寸小光斑变化成环形中空光斑,并且通过光瞳滤波器...     

A method of whispered speech enhancement based on speech absence probability and modified mel-domain masking model

Whispered speech enhancement using auditory masking model in modified Meldomain and Speech Absence Probability(SAP)was proposed.In light of the phonation characteristic of whisper,we modify the Mel-frequency Scaling model.Whispered speech is filtered by the proposed model.Meanwhile,the value of masking threshold for each frequency band is dynamically determined by speech absence probability.Then whispered speech enhancement is conducted by adaptively rectifying the spectrum subtraction coefficients using different masking threshold values.Results of objective and subjective tests on the enhanced whispered signal show that compared with other methods;the proposed method can enhance whispered signal with better subjective auditory quality and less distortion by reducing the music noise and background noise under the masking threshold value.     

基于色调恒定的MSR图像增强算法

由于多尺度Retinex算法增强后图像存在细节信息减弱和颜色失真等不足,本文提出了一种色调恒定的图像增强算法.在原图像中去掉用多尺度高斯函数估计的光照分量,结合参量自适应的非线性函数调整亮度,依据色调恒定的理论保持增强后图像的颜色.与多尺度Retinex比较的实验结果表明,本文算法更有效,增强后的图像不仅细节清晰,而且...     

Leibniz Conformal Algebras of Rank Two

We classify all Leibniz conformal algebras of rank two.     

电解沉积的分形维数与ZnSO_4溶液浓度的关系

用电沉积方法得到了不同浓度硫酸锌电解液的分形凝聚图像;进行图像处理,得到了其分形维数与浓度的关系曲线;用粒子扩散限制凝聚模型解释了此关系     

BIT新型分散染料的合成及性能研究

以3-氨基-5-硝基2,1-苯并异噻唑(BIT) 为重氮组分,在适当的条件下,与单苯胺类及萘胺磺酸类衍生物偶联, 得到了从红到兰色的一系列分散染料. 这些染料均未见报导,并对其中部分染料进行了检测,证明各项性能优良,应用前景看好.     

小麦液泡膜H~ -ATPase的Ca~(2 )激活特性

纯化小麦液泡膜H -ATPase,测定了纯化的小麦液泡膜H -ATPase 受Mg2 和Ca2 双重激活的特性及两种激活状态下酶的特性. Mg2 激活时酶水解活性受DCCD的抑制,受磷脂酰丝氨酸(PS)影响明显,ATP水解和泵质子活性相偶联.而在Ca2 激活时酶水解活性不受DCCD抑制,受PS影响微弱,Ca2 激活时ATP水解与泵质子活性解偶联. Mg2 和Ca2 对小麦液泡膜H -ATPase的激活作用不具有叠加效应.     

植物病毒病化学防治剂的探寻 Ⅺ.三羧酸乙基DHT酯的合成及抗病毒活性

合成了１０个未见文献报道的三羧酸乙基ＤＨＴ的酯类化合物,新化合物的水溶性、脂溶性均较ＤＨＴ好,并有一定抗病毒活性,其中化合物２的活性最高,对ＴＭＶ的抑制百分率达到９０％,优于对比的ＤＨＴ     

我国普通高等教育人力资源发展水平的统计分析

本文综合运用主成分分析和因子分析两种综合评价方法 ,对我国各地区高等教育人力资源的发展水平进行排序和分类 ,为规划和发展各地区的高等教育事业提供了一定的科学依据。两种综合评价方法的综合运用克服了单一评价方法的片面性 ,评价结果较为全面、客观