糠醛在银镜上的表面增强拉曼光谱研究

研究糠醛分子的常规拉曼谱（NRS）和在银镜上的表面增强拉曼光谱（SERS）谱,通过运用DFT（density functional theory,密度泛函理论）计算了FUR（Furfural）的分子振动光谱,对拉曼峰进行指认,并给出了糠醛在银镜上的吸附状态．     

真假茅台酒在银胶上的SERS光谱分析

利用显微拉曼技术研究了真、假茅台酒的正常拉曼光谱(Normal Raman Spectroscopy)和表面增强拉曼光谱(Surface Enhanced Raman Spectroscopy).在室温环境下,得到了真、假茅台酒的在632.8 nm激发光下的NRS,但是它们谱图差别不太明显.通过研究活性衬底银胶上真、假茅台酒的SERS,结果显示,它们的SERS谱差异明显.特别是在真茅台酒的SERS中,出现了属于其主要香味成分糠醛的谱峰,而在假茅台酒SERS中,这些峰不出现或者强度很弱.因此SERS光谱法可以作为鉴别茅台酒品质和真伪的一种手段.     

Power-efficient topologies for wireless sensor networks with fixed communication range

The expectations for sensor networks are growing. The performance of wireless sensor networks （WSNs） is greatly influenced by their network topology. In this paper, we consider four patterned topologies that best support connectivity among these deployed sensor nodes in two-tiered WSNs. The theoretical and simulation results show that the triangle-based topology has smaller cell number, shorter maximum hop length, less total energy consumption, and better performance than other topologies. The analysis carried out in this paper could provide the guidelines for network deployment and protocol design in the future applications.     

金属光栅的表面拉曼散射

以纳米量级金履带矩形光栅为模型,研究了表面增强拉曼散射的特性。针对TM和TE模的入射光,采用严格的耦合波原理对金属表面衍射场进行计算。通过计算,具体讨论了光栅周期、占空比、深度以及入射光的波长和入射角对表面增强的影响。     

纳米银溶胶的制备及其与荧光素相互作用的研究

以太阳为光源,以硝酸银和柠檬酸三钠为反应试剂、聚乙烯吡咯烷酮为保护剂,通过控制光照时间和光照强度,制备了蓝色和红色纳米银溶胶,比较了两种不同颜色纳米银溶胶形成过程的UV-Vis吸收光谱;采用UV-Vis分光光度法和荧光法研究了荧光素和两种颜色纳米银溶胶的相互作用。实验发现,纳米银的加入使得荧光素的吸收峰红移,并使得荧光素荧光增强。     

光化学还原法制备绿色纳米银溶胶

以高压汞灯作为反应光源,以硝酸银和柠檬酸三钠(TSC)为反应试剂,以聚乙烯吡咯烷酮(PVP)为保护剂,建立了水溶液中一步光化学还原快速制备绿色纳米银溶胶的简便方法.研究了光照时间、TSC的浓度、转速等反应条件对纳米银胶的影响及纳米银胶的稳定性,采用紫外-可见分光光度法、共振散射光谱法和扫描电镜对纳米银胶进行了表征.结果表明,反应时间及TSC的浓度均会影响纳米银胶的性质,制备得到的绿色纳米银胶粒子为高分散准球形,且在室温避光条件下十分稳定.此外,实验发现,通过控制TSC的浓度可以制备得到具有不同光谱性质的绿色纳米银胶.     

Studying creation of bulk elementary excitation by heaters in superfluid helium-II at low temperatures

In this paper, the obtained experimental results concerning creation of bulk elementary excitations (BEEs) in iso-topically pure liquid 4He at low temperatures ~60 mK are discussed. Positive rotons’ (R -rotons) creation by a pulsed heater was studied. Signals were recorded for the following quantum processes: quantum evaporation of 4He-atoms from the free liq- uid-helium surface by the BEEs of the liquid helium-II, and BEEs reflection from the free surface back into the bulk liquid. Typical signals are shown, and ratios of signal amplitudes are evaluated. For long heater pulses from 5 to 10 μs, appearance of the second atomic cloud consisting of evaporated 4He-atoms was observed in addition to the first atomic cloud. It is thought that the first atomic cloud of the evaporated helium atoms consists of very fast 4He-atoms with energies ~35 K evaporated by positive rotons with the special energies ~17 K (~2ER~2×8.6 K with ER representing the roton minimum energy) corresponding to the third non-dispersive Zakharenko wave. The second cloud of slower 4He-atoms was created by surface elementary excitations (SEEs or ripplons) possessing the special energies ~7.15 K representing the binding energy. It was assumed that such SEEs can be created by phonons incoming to the liquid surface with special energies ~6.2 K corresponding to the first non-dispersive Zakharenko wave, which can interact at the liquid surface with the same phonons already reflected from the surface for long heater pulses. Also, some pulsed-heater characteristics were studied in order to better understand the features of such heaters in low temperature experi- ments.     

熔融拉锥型全光纤耦合器性能分析

针对市场上最急需的,生产中最常用的熔融拉锥型全光纤耦合器,介绍了它的工作原理、制作方法以及参数测量等内容,从实验上测量了所生产光纤耦合器的插入损耗、工作波长、方向性以及工作温度等,通过实验测试表明我们所生产的光耦合器器从各项指标上都达到了实用要求。     

新型SERS光纤探针的制备

以单模石英光纤为材料，首先用管腐蚀的方法制备出光纤探针，然后在管表面镀一层银膜，构成具有表面增强特性的管状光纤探针。将光纤探针应用到拉曼光谱仪上，实际测量了几个具有代表性样品的拉曼光谱，实验表明效果较好。     

紫外光诱导三角形银纳米粒子形成球形银纳米粒子及SERS研究

以聚乙烯吡咯烷酮为保护剂,制备三角形银纳米粒子溶胶。用紫外灯对三角形银纳米粒子溶胶进行光诱导实验。利用透射电子显微镜、紫外-可见吸收光谱和拉曼光谱仪研究了不同光照时间下的银胶纳米粒子的光谱特性和表面形貌,以PATP为探针分子检测银胶纳米粒子的表面增强拉曼散射光谱。实验结果表明：随着光照时间的增多,银纳米粒子溶胶颜色变化显著;紫外-可见吸收光谱吸收峰出现＂蓝移＂;透射电子显微镜图显示银纳米粒子由三角形逐渐转变成截角三角形银纳米粒子、球形银纳米粒子;表面增强拉曼散射的增强效应随着光照时间的变化逐渐减小。     

Parameters optimization and nonlinearity analysis of grating eddy current displacement sensor using neural network and genetic algorithm

A grating eddy current displacement sensor （GECDS） can be used in a watertight electronic transducer to realize long range displacement or position measurement with high accuracy in difficult industry conditions. The parameters optimization of the sensor is essential for economic and efficient production. This paper proposes a method to combine an artificial neural network （ANN） and a genetic algorithm （GA） for the sensor parameters optimization. A neural network model is developed to map the complex relationship between design parameters and the nonlinearity error of the GECDS, and then a GA is used in the optimization process to determine the design parameter values, resulting in a desired minimal nonlinearity error of about 0.11%. The calculated nonlinearity error is 0.25%. These results show that the proposed method performs well for the parameters optimization of the GECDS.     

表面增强拉曼光谱在食品质量与安全检测中的应用

表面增强拉曼光谱（SERS）技术具有操作简便、灵敏度高、无需复杂样品前处理,可适用于现场快速分析等优点,在农业、食品、医药、生物和化学等领域开始得到应用。本文主要介绍了SERS及其基底的研究,综述了近年来SERS技术在食品质量与安全检测中的应用。     

小锥度POF光传输特性的分析

理论分析了小锥度POF的光传输特性,讨论了锥形POF的径向光强分布和传输效率,并实验验证了理论计算结果的正确性,说明小锥度POF可用于不同芯径光纤的过渡连接.     

Exploring the atmosphere with lidars

In Part 1¹, we described the basic principle of the lidar (Light Detection and Ranging), the different scattering processes in the atmosphere and the Mie and Rayleigh lidars. In this part, we describe three other types of lidars: Raman lidar, differential absorption lidar (DIAL) and doppler lidar. A lidar system consists of a pulsed laser which sends out pulses of laser light and a sensor that senses the scattered light from the different molecules and aerosols in the atmosphere. The characteristics of the scattered light are used to determine the nature and amount of the constituents.     

双锥体天线输入阻抗的计算

求解大锥角双锥体天线的输入阻抗,综合阻抗和增益两方面的因素可以确定θ0=45°角的双锥体天线其宽带特性最好．因此,本文着重针对θ0=45°角双锥体天线展开研究,利用计算机求出其输入阻抗的一级近似并画出阻抗特性和输入阻抗的函数图．     

A novel voltage output integrated circuit temperature sensor

The novel integrated circuit (IC) temperature sensor presented in this paper works similarly as a two-terminal Zener, has breakdown voltage directly proportional to Kelvin temperature at 10 mV/℃, with typical error of less than ±1.0℃ over a temperature range from -50℃ to +125℃. In addition to all the features that conventional IC temperature sensors have, the new device also has very low static power dissipation ( 0.5 mW ) , low output impedance ( less than 1Ω), excellent stability, high reproducibility, and high precision. The sensor's circuit design and layout are discussed in detail. Applications of the sensor include almost any type of temperature sensing over the range of -50℃-+125℃. The low impedance and linear output of the device make interfacing the readout or control circuitry especially easy. Due to the excellent performance and low cost of this sensor, more applications of the sensor over wide temperature range are expected.     

An analytical model for predicting sheet springback after V-bending

INTRODUCTION As an important manufacturing method, bending has been widely used in modern industries to produce stamping parts such as frames, channels, braces, brackets and other structural parts. The understanding and development of bending mechanics are aimed at achieving two kinds of information which are very important for industrial production. One is to predict springback for dies design and compensation in order to obtain high dimension accuracy of bending parts. The other is to …     

憎液溶胶在工业生产中的应用

溶胶可分为亲液溶胶和憎液溶胶。在很多方面有着应用,憎液溶胶由于其特殊的结构、性质,使得它在生产、生活的方面有着不可替代的作用。憎液溶胶主要应用于表面活性剂方面。本文对于憎液溶胶的性质及应用做了一些简要的介绍,从中可以看出憎液溶胶在生产、生活等方面的重要性以及它的应用前景。     

Real-time localization estimator of mobile node in wireless sensor networks based on extended Kalman filter

Localization of the sensor nodes is a key supporting technology in wireless sensor networks (WSNs). In this paper, a real-time localization estimator of mobile node in WSNs based on extended Kalman filter (KF) is proposed. Mobile node movement model is analyzed and online sequential iterative method is used to compute location result. The detailed steps of mobile sensor node self-localization adopting extended Kalman filter (EKF) is designed. The simulation results show that the accuracy of the localization estimator scheme designed is better than those of maximum likelihood estimation (MLE) and traditional KF algorithm.     

聚二甲基硅烷与聚二甲基硅氧烷链特征比分析比较

应用构象统计方法和改进的侧基旋转异构态模型,推导了对称取代基链的均方回转半径特征比《S2》/2xl2公式,可研究聚二甲基硅烷链的柔顺性,根据特征比与链长的关系,得到聚二甲基硅烷链长链特征比值0.94,结果还与聚二甲基硅氧烷链前期计算值作了比较.