单个波长到多个波长的变换实验

报道一种波长变换的新方法.采用此方法不需要任何泵浦光便能够直接将信号光变换成在特定谱宽内的任意多个任意波长的变换光,这对于将来的波分复用光网络提供了较大的方便.此波长变换的原理是利用色散位移光纤的非线性效应产生超连续光谱(SC)信号,由于这种SC信号携带有变换光信号,对这种连续谱进行滤波便能够得到所需要的任意频率的变换信号.此变换方式具有变换频带宽,偏振不敏感的优点。     

金属Zn液态结构变化的研究

利用ＴＢ模型给出的原子间相互作用势详细计算了不同温度下Ｚｎ的双体分布函数ｇ（ｒ），结果发现随着温度的不断降低，液态金属Ｚｎ的ｇ（ｒ）第一峰变得高而尖，第二峰由弱变强，说明了液态金属Ｚｎ的有序度随温度降低而不断增强；利用键对分析技术统计了液态金属Ｚｎ在不同温度下的键取向序参数、键对数。键取向序参数及键对数随温度的变化，进一步证明了低温液态的有序度高于高温液态，从而充分说明液态金属在不同温度下有不同的结构形式，而不像人们想象得那样杂乱无章。     

Mobile Rayleigh Doppler wind lidar based on double-edge technique

<正>We describe a mobile molecular Doppler wind lidar(DWL) based on double-edge technique for wind measurement of altitudes ranging from 10 to 40 km.A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity.The lidar operates at 355 nm with a 45-cm-aperture telescope and a matching azimuth-over-elevation scanner that provides full hemispherical pointing.To guarantee wind accuracy,a single servo loop is used to monitor the outgoing laser frequency to remove inaccuracies due to the frequency drift of the laser or the etalon.The standard deviation of the outgoing laser frequency drift is 6.18 MHz and the corresponding velocity error is 1.11 m/s.The wind profiles measured by the DWL are in good agreement with the results of the wind profile radar(WPR).Evaluation is achieved by comparing at altitudes from 2 to 8 km.The relative error of horizontal wind speed is from 0.8 to 1.8 m/s in the compared ranges.The wind accuracy is less than 6 m/s at 40 km and 3 m/s at 10 km.     

Effect of polarization on efficiency of volume Bragg grating filter

<正>Diffraction efficiency of volume Bragg grating,whose period is in the same order as the incident wavelength, is related to the polarization direction of the incident linear polarized beam.When two linearly polarized recording beams with the same polarization direction are used for recording volume Bragg gratings in a photopolymer with diffusion amplification,the azimuth of polarization of the reconstruction beam influences the diffraction efficiency of the grating.When the probe beam is linearly polarized and oriented orthogonally to the grating vectors,the±1-order diffraction beams are also linearly polarized with polarization direction parallel to that of the probe beam.According to the results,a two-dimensional nonspatial optical filter consisting of the volume Bragg gratings would achieve significantly higher efficiency.     

爆炸磁压缩发生器爆炸管运动研究

 报导了对爆炸磁压缩发生器(MFCG)的爆炸管进行的爆轰试验结果。用电子学方法测试了爆炸管采用的粉状RDX炸药的爆轰速度;采用高速分幅摄影方法,观测了爆炸管在管内RDX炸药爆轰产物驱动下的膨胀运动过程,测试了膨胀角、对称性和膨胀速度。试验表明,爆炸管在膨胀至 3倍初始半径内未发现破裂现象,其性能满足MFCG的设计要求。     

Decay properties of D and D_s mesons in coulomb plus power potential （CPPν）

The decay properties of the D and D s mesons are computed in a nonrelativistic phenomenological quark-antiquark potential of the type V （r） =-4 /3 α s /r＋ Ar ν with different choices of ν.Numerical method to solve the Schrdinger equation has been used to obtain the spectroscopy of qQ mesons.The numerically obtained radial solutions are employed to obtain the decay constant and leptonic decay widths.It has been observed that predictions of the ground state masses and the decay widths are consistent with other model predictions as well as with the known experimental values.     

偏振激发-能量色散X-射线荧光光谱法快速分析地质样品中34种元素

报道了利用偏振激发 能量色散X 射线荧光光谱法快速定量分析地质样品中 34种元素所得到的结果。制样方法采用粉末压片法。原子序数低于Fe的元素采用基本参数法 ,Fe及其他元素采用散射线内标法进行校准。实验中分别采用了高取向热解石墨 (HOPG) ,Al2 O3 ,Mo ,Co等不同偏振靶 (或二级靶 ) ,对目标元素组进行选择激发和探测。在总测量时间为 6 0 0s·(每个样品 ) -1的条件下 ,得到的各元素的检出限达到 0 5～ 30 μg·g-1。     

近红外漫反射光谱法测定玉米秸秆NDF与ADF含量

应用主成分空间和傅里叶变换近红外光谱技术,采用偏最小二乘回归法(PLS),在国内首次建立了适合不同品种类型、不同生长发育时期和不同部位且适配范围广的近红外漫反射光谱(NIRS)测定玉米秸秆中性洗涤纤维(NeutralDetergentFiber,NDF)和酸性洗涤纤维(AcidDetergentFiber,ADF)含量的稳定校正模型。结果表明,采用一阶导数 矢量归一化预处理和一阶导数 多元散射校正预处理,谱区均为7502～5450cm-1和4601～4247cm-1,所建立的NDF与ADF校正模型,其校正和预测效果最佳。其校正决定系数(R2cal)均大于094,交叉验证和外部验证决定系数(R2cv,R2val)为092～096,各项误差(RMSEE,RMSECV和RMSEP)为149%～181%。该结果对青贮玉米秸秆材料快速鉴定和筛选具有重要的意义。     

Possible triggering of solar activity to big earthquakes (Ms ≥ 8) in faults with near west-east strike in China

A big earthquake (Ms = 8.1) occurred at western Kunlun Mts gap on November 14, 2001. It is the biggest earthquake in China in the past 50 years and the only one with a magnitude bigger than 8 in China after Dangxiong Earthquake (M = 8) in Tibet in 1951. The big earthquake has drawn wide attention of scientists in seismological, geophysical, geological and astro-geodynamic circles. Scientists are interested in the occurrence regularity of the very big earthquakes and try to find out the fac…     

用于机械振动实时监测的光纤光栅有源传感装置

把一对中心反射波长分别为1562.11nm和1562.71nm的光纤光栅粘贴在均质、等厚、等腰三角形悬臂梁上下表面作为环形腔光纤激光器端镜，当机械振动激励自由端时，通过观测激光输出脉冲，地施加于自由端的机械振动的频率进行了实时监测；观察两光栅波长漂移量差值的变化，可在0～6.1mm的范围内判断所测振动的振幅。低于100Hz时，实验结果与实际值基本吻合。