基于旋转曲面变换PSO算法的神经网络用于胺类有机物毒性分类

神经网络模型能有效地模拟非线性的输入输出关系。本研究应用三层前馈网络对51种胺类有机物进行了结构-毒性关系的分类研究。常规的神经网络权值训练算法,例如误差反传算法,存在着收敛速度慢,容易陷入局部极值点等问题。因此提出旋转曲面变换粒子群优化算法,将被优化函数的局部极小点变换为全局最大点,同时不改变比局部极小点的值更小的区域的函数形状。此方法和粒子群优化相结合,能使待优化函数跳出局部极值点,提高训练神经网络权值的效率。实验结果显示,基于旋转曲面变换粒子群优化算法的神经网络,权值训练过程收敛速度较快,且自检误差和预报误差都较小,是一种有效的胺类有机物毒性分类方法。     

利用受激布里渊散射改善偏振抽取腔光束质量的研究

在理论上分析了受激布里渊散射相位共轭效应和阈值效应对后向受激布里渊散射光束发散角的影响。在实验上，用受激布里渊散射相位共轭镜（SBS PCM）代替普通反射镜构成Nd:YAG激光器的偏振抽取腔，补偿了激活介质和光学元件造成的波前畸变，压缩了发散角，改善了光束质量。研究了抽运能量、透镜焦距等因素对受激布里渊散射偏振抽取腔输出光光束质量的影响。     

SO2的简并四波混频光谱

简并四波混频（DegenerateFour－WaveMixingDFWM）是一项非线性光谱技术·近年来，它被成功地用于气相痕量原子、分子和自由基的探测［1，2］，而受到人们的关注．DFWM具有亚多普勒的光谱分辨、良好的时间和空间分群等特点，可以实现远距离探测，能有效地排除背景光干扰．此外，由于DFWM技术是直接用于探测体系的吸收，可以应用于无荧光或荧光量子产率低的体系和激发态具有电离和预解离等竞争通道的体系，而这两种体系用传统的激光诱导荧光（LIF）和共振多光子电离（REMPI）方法很难探测．Dreier和Rakestraw曾用DFWM技术探测火…     

用自适应偏最小二乘回归为药物定量构效关系建模

提出了一种自适应偏最小二乘回归（APLSR）方法。对于指定的预测对象，APLSR将根据样本在结构参数空间中的分布，分析它们对预测对象的预报能力，自适应地为各个样本分配权值，并从样本数据中提取和选用PLS成分，从而实施自适应加权PLSR，以获得预报性能良好的模型，作者将APLSR应用于含硫苯衍生物的QSAR建模，取得了令人满意的效果。     

在阴离子表面活性剂存在下,漂蓝6B分光光度测定矿石中的微量铍

漂蓝6B(ECAB)是一种有实用价值的显色剂。十二烷基硫酸钠(SDS)对吡啶偶氮衍生物与某些金属离子体系有强烈的增敏作用,但阴离子表面活性剂对三苯甲烷酸性染料与金属离子的络合物体系的增敏作用尚未见报导。本文研究了SDS对三苯甲烷类酸性染料之一——ECAB与铍络合物体系的增溶增敏作用。结果表明,在SDS存在下,在pH6.3左右,Be(Ⅱ)-ECAB体系的最大吸收波长为616nm,试剂空白在此波长下吸光度很低,表观摩尔吸光系数为1.11×10~5,比相应的二元络合物灵敏度提高4倍多,亦比采用阳离子表面活性剂作增敏剂时灵敏度高。该体系具有显色速度快,络合物稳定性好,不沾污吸收池和容量瓶,实验操作简便等优点。加入掩蔽剂后,已被用于直接测定矿石中微量铍及铜铍合金试样中含铍量,获得了满意的结果。     

Laser-induced quadrupole-quadrupole collisional energy transfer in Xe-Kr

By considering the relative velocity distribution function and multipole expansion interaction Hamiltonian, a three-state model for calculating the cross section of laser-induced quadrupole-quadrupole collisional energy transfer is presented. Calculated results in Xe-Kr system show that in the present system, the laser-induced collision process occurs for ～4 ps, which is much shorter than the dipole-dipole laser-induced collisional energy transfer (LICET) process. The spectrum of laser-induced quadrupole-quadrupole collisional energy transfer in Xe-Kr system has wider tunable range in an order of magnitude than the dipole-dipole LICET spectra. The peak cross section decreases and moves to the quasi-static wing with increasing temperature and the full width at half peak of the profile becomes larger as the system temperature increases.     

Medium performance effect on the high output energy from a xenon lamp-pumped pyrromethene-567 solid-state dye laser

In order to obtain a high output energy from a xenon lamp-pumped solid-state dye laser, homogeneities of laser mediums and flatnesses of medium faces with different processing treatments are discussed in the paper. The medi- ums without aging treatment, which are prepared by using a prepolymer process and have diamond-machined end faces to produce the required optical finish, give a highest laser output of 281.9 mJ with 0.215% slope efficiency at 2.0×10 4 mol/L. The best medium lifetime is 21 shots to 50% of original output equating 74.6 kJ/liter.     

Observation of Two Quasi—Static Wings of Laser—Induced Collision Energy Transfer

We investigate experimentally laser-induced collision energy transfer for transitions both from Eu(6s6p)^8 P9/2 to Sr(5s10s)^1So and from Eu(6s6p)^s-P7/2 to Sr(5s8d)^1D2.Two quasi-static wings are observed in their excited function spectra.By using two dipole-dipole interactions,a spectral line from numerical calculation is consistent with the experimental line in two quasi-static wings.     

Nd：YAG固体脉冲激光器实验研究

介绍了Nd：YAG固体脉冲激光器相关的实验项目：静态和调Q状态的出光阈值、激光脉宽、倍频和激光光束形状等.采用普通相纸、红外相纸和激光能量计检测出不同的激光器静态和调Q出光阈值;采用散射、反射和透射方法研究了静态和调Q输出激光脉冲的宽度,发现用K9玻璃和多层膜镜测试的激光脉冲宽度比散射方法的大;采用激光能量计测试激光器静态和调Q的倍频效率和倍频激光能量与倍频晶体的位置关系;激光光束探测器表征激光器静态和调Q输出光的光斑形状.通过这些实验项目,学生将深入了解和掌握固体脉冲激光器的工作原理、性能参数,以及表征激光器性能参数的仪器设备,并深入地研究解决实验发现的问题,为今后激光相关领域的工作奠定坚实的基础.     

Study on optical anisotropy properties of SiO2 films with different thermal annealing temperatures

SiO2 films are deposited on Si substrates by an ion beam sputtering technique and continuously annealed in a quartz culture dish in air at various annealing temperature ranging from 20 to 750 ℃ with a step of 100 ℃ for a fixed time of 24 h. The effects of thermal treatment on optical anisotropy properties of SiO2 films are investigated by spectroscopic ellipsometry. When the annealing temperature is 550℃, the optical anisotropy properties of SiO2 film is minimum. The obtained results indicate that the optical anisotropy properties of SiO2 films can be improved by a proper thermal annealing process.