用喇曼增强非简并四波混频测量喇曼模的横向弛豫时间

在频率域研究了用喇曼增强非简并四波混频(RENFWM)测量喇曼模的横向弛豫时间,得到消背底的RENFWM光谱,对实验曲线进行拟合,获得苯和甲苯的振动模的横向弛豫时间分别为1.5ps和2ps。     

对二氯苯喇曼谱用于激光喇曼分光计中杂散光的半定量测试

本文详细研究了近波数区(20cm~(-1)附近)对二氯苯喇曼谱峰背比与激光喇曼分光计中杂散光的定量关系,并在此基础上提出了一种测试激光喇曼分光计中杂散光的半定量方法。     

Nd：LiTaO3背散射组态下的喇曼光谱异常

本文研究了掺钕钽酸锂组体背射几何组态下的喇曼光谱，与纯钽酸锂晶体的喇曼光谱相比，发现喇曼谱中不仅有Ｅ（ＬＯ＋ＴＯ）模向Ａ１（ＴＯ）模的转变，而且还有新振动模的出现和部分振动模强度的变化，本文用光折变理论结合掺杂后晶体微观结构的改变对实验结果作了分析和探讨。     

XeCl准分子激光在铅蒸气中的高效率受激电子喇曼散射

本文报道了采用非稳腔XeCl准分子激光泵浦铅蒸气获得52%喇曼能量转换效率.比较了稳腔与非稳腔XeCI激光泵浦下的喇曼转换特性.     

部分离化激光等离子体的受激喇曼散射不稳定性

由于部分离化激光等离子体中存在束缚电子，它可显著改变其参量不稳定性。本文分析了部分离化激光等离子体的受激喇曼散射的非线性色散关系，计算了钕玻璃倍频和三倍频激光受激喇曼散射的增长率，结果表明，前向受激喇曼散射显著增强，后向受激喇曼散射影响不大。     

蛋白质结构和功能的紫外共振喇曼光谱研究

紫外共振喇曼光谱技术是研究复杂大分子结构的有力工具。结合作者在美国Pittsburgh University期间所做的工作，介绍了用紫外共振喇曼光谱研究肽和蛋白质结构与功能的现状和进展，N-methylacetamide和glycyglycine水溶液光化学异构过程的紫外共振喇曼光谱研究，简述了紫外共振喇曼光谱实验技术要点。本文还跟踪国际最新研究成果，介绍了利用紫外共振喇曼光谱技术研究蛋白质的折叠和去折叠过程。     

固体的光散射讲座 第四讲 非线性喇曼散射

非线性喇曼散射是指由于分子的偶极矩或激活介质的宏观极化矢量与光电场强度呈非线性关系,所引起的喇曼散射过程.在自发散射过程的理论描述中,振动着的分子体系的偶极矩可以写成其中q为分子振动的简正坐标,u为分子体系的固有偶极矩,α(q)称为分子体系的极化率,β(q)等则可称为超极化率.显然,上式中第二项所引起的喇曼散射是线性的,第三项以后各项所引起的喇曼散射则属于非线性的,其中由β(q)所引起的喇曼散射则称为超喇曼散射[1,2] 当人射光较弱时,自发的线性及非线性喇曼散射效应都非常弱,而且它们是非相干的散射.当人射的泵浦光较强时,再…     

亚微米直径光纤的非线性特性研究

用电磁场的严格解分析了亚微米直径光纤的非线性系数，发现光纤直径在700 nm左右（亚微米量级）非线性系数较大，喇曼阈值较小，喇曼增益谱线较多；受激喇曼散射特性的分析表明，由于直径小，光纤在较小的泵浦光功率作用下能量密度就很大，因此很容易观察到受激喇曼散射.实验结果表明，理论分析与实验结果吻合得很好.     

光纤共振和预共振喇曼光谱(英)

在液芯光纤内产生共振和预共振喇曼效应，喇曼光谱强度可以大幅度提高，最高可达109倍．本文介绍获得光纤（预）共振喇曼光谱的可行性、实验及实验结果．用远离吸收带的激光激发获得了α甲基吡啶预共振喇曼光谱．用小功率激光（0．8mW）、低浓度溶液（9．6×10(-12)mol／L）还获得了β叶红素在CS2中的共振喇曼光谱．     

热丝CVD生长金刚石薄膜喇曼散射研究

本文报道热丝化学气相沉积法（ＨＦＣＶＤ）生长金钢石薄膜的喇曼散射结果。选取多种峰型，对金钢石薄膜喇曼谱（１１０－１８００ｃｍ－１）采用最小二乘法进行非线性拟合，得到最佳拟合模型，其计算得到的拟合曲线怀实验谱图符合得较好。该模型揭示，石墨Ｄ峰（１３５５ｃｍ－１）是金刚石薄膜喇曼谱中不可缺少的一个组份，并且结合石墨Ｄ峰和金刚石喇曼的空间相关线型，可以解释金刚石喇曼区特殊峰形的物理机制，拟合参量的进一步     

运动背景下弱小目标的提取算法

 对低信噪比运动背景下序列图像中弱小目标的提取算法进行了研究，提出一种新的目标提取算法。根据运动背景的相关性和目标运动的连续性，采用背景模板匹配技术，计算各帧背景运动量，去除复杂背景，用自适应预估和阈值分割技术捕获跟踪目标。实验中，结合所研究的算法，对100帧包含低对比度弱小目标的运动图像序列进行了处理。实验结果表明，此方法能有效地实现目标的自动捕获与跟踪，跟踪效率高，跟踪稳定。     

Energy budget of cosmological first-order phase transition in FLRWbackground

We study the hydrodynamics of bubble expansion in cosmological first-order phase transition in the Friedmann-Lema??treRobertson-Walker(FLRW) background with probe limit. Different from previous studies for fast first-order phase transition in flat background, we find that, for slow first-order phase transition in FLRW background with a given peculiar velocity of the bubble wall, the efficiency factor of energy transfer into bulk motion of thermal fluid is significantly reduced, thus decreasing the previously-thought dominated contribution from sound wave to the stochastic gravitational-wave background.     

Small target detection using main directional suppression high pass filter

Small target detection in deep space background with a complex background is one of the most important tasks in space technology. Undulant background and stars have a great influence on the target detection for low signal to noise ratio targets of imagery. In this paper, a main directional suppression high pass filter is proposed for background suppression, furthermore applied in small target detection. First, target and background models are created. Second, the problems and the necessity of the deep space background suppression are proposed. Then, the main directional suppression high pass filter is presented for background suppression. Experimental results prove that the presented algorithm is efficient and adaptable to small and dim target detection under undulant background with star lines.     

低对比度小目标检测

对强杂波背景下的远距离目标探测,提出基于序列图像的局部自适应背景预测,获得图像背景的最佳估计。对残差图像采用能量累积及中值滤波消除背景杂波。为提高信噪比,采用带缓冲窗口的双窗滤波法使目标和背景的差别更加显著,有利于低对比度下的目标分割。最后采用改进的高阶相关方法,在不影响检测性能的情况下加快了真实目标识别的运算收敛速度,并最终实现了算法工程化,在图像局部信噪比大于0.3时,采用三阶相关时检测概率达到98%。     

开路光伏空间孤子的动态行为

从理论上研究了开路情况下一维光伏空间孤子的时间演化过程.采用数值方法,通过研究有无背景光辐照下光伏空间亮(暗)孤子的含时空间电荷场,分别得到了光伏空间亮(暗)孤子的孤子波形强度微分方程.在此基础上研究了开路情况下通过增加均匀背景光辐照强度对光伏空间孤子及其半峰全宽的影响.结果显示,通过增加均匀背景光辐照强度,光伏空间孤子随时间的演化过程比没有均匀背景光时加快的倍数为均匀背景光强与暗辐照光强之比.光伏空间孤子的半峰全宽达到稳态所需的时间随孤子峰值强度和暗辐照与均匀背景光强度之和的比值的增大而变短.     

火焰原子吸收法测定钢铁中钴时的背景吸收及消除

对于背景校正装置的原子吸收分光光度计,用火焰原子吸收法测定钴时,由于铁等有背景吸收（指铁的背景通过吸收池以后的背景,称为背景吸收）,故无法用标准加入法测定钢铁中低含量钴。本文对测钴时的背景吸收及铁的干扰做了详细的研究,用金２４２．８ｎｍ谱线做为测钴时背景吸收校正线,可完全扣除背景吸收。用标准加入法测定了钢及高温合金中低含量钴。     

合成孔径雷达反演海面风场变分模型分析

为考察合成孔径雷达反演海面风场变分模型精度,开展了误差分析试验.在背景场误差为极大值条件下分析场误差低于背景场误差,且随背景场风向增大呈周期性变化;在背景场误差逐渐变大条件下分析场误差逐渐增大,误差偏离方向与背景场误差偏离方向一致;在特定背景场条件下与直接反演模型相比,低风速时反演误差略高,中高风速时反演误差明显较低.总体来讲,变分模型误差小于背景场误差,风速反演误差小于1.60 m/s,风向误差小于17.15°.     

Lateralization of coherent and incoherent targets added to a diotic background

Lateralization responses to noise targets were obtained in a diotic noise background. On each trial, a noise target was added to the background noise in one earphone. Subjects were required to identify the earphone containing the target. Noise targets were either coherent or incoherent with the background. The long-term power spectrum of the incoherent target was identical to that of the background noise, and its amplitude was adjusted so that the addition of either the coherent or incoherent target to the background produced the same average increment in power. When 50-ms noise targets were presented in the middle of a 750-ms diotic background, lateralization thresholds were lower for the incoherent targets. The advantage with incoherent targets was shown to depend on the temporal relationships between target and masker. Superior performance with incoherent targets is inconsistent with predictions based on an analysis of interaural phase and amplitude differences. Models based on interaural subtraction, on the other hand, are able to account for the lateralization advantage shown by incoherent targets but are unable to account for the variations in threshold produced by altering the temporal relationships between target and masker.     

Auditory evoked potentials in females with high and low acceptance of background noise when listening to speech

Acceptable noise level (ANL) is a measure of a listener's acceptance of background noise when listening to speech. A consistent finding in research on ANL is large intersubject variability in the acceptance of background noise. This variability is not related to age, gender, hearing sensitivity, type of background noise, speech perception in noise performance, cochlear responses, or efferent activity of the medial olivocochlear pathway. In the present study, auditory evoked potentials were examined in 21 young females with normal hearing with low and high acceptance of background noise to determine whether differences in judgments of background noise are related to differences measured in aggregate physiological responses from the auditory nervous system. Group differences in the auditory brainstem response, auditory middle latency response, and cortical, auditory late latency response indicate that differences in more central regions of the nervous system account for, at least in part, the variability in listeners' willingness to accept background noise when listening to speech.     

氮气低温除氡技术与极低水平氡测量方法研究

高纯低本底氮气在低本底实验中有重要作用,对氮气的放射性氡本底纯化技术和低本底氡测量方法进行研究非常重要。利用低温物理吸附技术,对氮气中的氡进行纯化,同时建立了静电收集结合低温富集法的氡测量装置, 能够测量氮气中10 μBq/m3的氡本底。利用氡测量装置测量了普通氮气中和纯化氮气中的氡,结果表明,纯化系统可以将氡本底为20 mBq/m3的氮气降低至(25.2±5) μBq/m3,即可将氡本底降低到纯化前的0.125%。研究还发现,纯化能力与氮气中氡本底相关,在氮气中氡本底为几十mBq/m3到几十μBq/m3范围内,随着氡本底的下降,纯化能力也随之下降。主要原因是,随着氮气中氡的分压降低,吸附能力下降。另外,在极低本底下由系统本底及泄露引入的氡污染影响显著增大。