基于扫描激光器的边孔光纤光栅温度压力传感系统

研究了一种基于波长扫描激光器的光纤温度压力测量系统.光纤传感头为边孔光纤光栅,利用其特有的双折射特性产生双反射峰,以实现对温度和压力的同时测量.系统采用嵌入式开发技术,将激光波长扫描、光谱数据采集和以牛顿最小二乘法为核心的光栅解调算法高度整合于一体,极大降低了光纤传感系统的体积与成本.实验结果表明,在温度10~50℃、压力0~1.2 MPa时,双反射峰对应温度与压力的变化均呈现良好的线性响应特性;系统的波长解调准确度可达1pm,温度及压力的分辨率分别达到0.1℃和0.1 MPa.该系统可为温度、压力的参量测量提供低成本、小型化、性能可靠的解决方案.     

嵌入式粒子群-遗传算法的水质COD检测特征波长优化算法

基于紫外-可见光谱法的水质测量中,光谱信号易受到系统噪声干扰、悬浮物散射干扰,且存在信息冗余、多重共线性等特征,导致水质COD测量中特征波长的选取产生较大偏差。因此,提出了基于嵌入式粒子群-遗传（EPSO_GA）算法的水质COD检测特征波长优化算法,以提高波长选择精度。为验证检测特征波长优化算法的可行性,采集了某高校池塘水样、生活污水和排水沟水样的光谱数据,利用EPSO_GA算法对预处理后的光谱数据选取特征波长。EPSO_GA算法采用实数编码方法实现了粒子群（PSO）优化算法和遗传（GA）优化算法的统一编码,在PSO算法中更新粒子时嵌入GA算法的选择、交叉、变异等操作,改善了这两种算法各自在光谱波长特征选取问题上的局限性。将EPSO_GA算法选取的特征波长结合偏最小二乘法（PLS）构建了EPSO_GA_PLS的水质COD预测模型,并且与传统的PSO算法、GA算法选取特征波长建立的PSO_PLS、GA_PLS和全光谱构建的PLS水质COD预测模型做了对比。结果表明：与PSO_PLS,GA_PLS和全光谱构建的PLS水质COD预测模型相比,EPSO_GA改善了PSO算法和GA算法在光谱特征波长选择中早熟和收敛速度慢的问题,降低了全光谱构建PLS水质COD预测模型的复杂度,提高了模型的预测精度。基于EPSO_GA算法建立的EPSO_GA_PLS水质COD预测模型,均方根误差降到了0.212 3,预测精度增加到0.999 3,可以快速定量检测水质COD,为紫外-可见光谱法测COD提供了更好的预测模型。     

A token-based routing mechanism for GMPLS-controlled WDM networks

This paper analyzes destination initiated reservation for Generalized Multi-Protocol Label Switching (GMPLS) based wavelength division multiplexing (WDM) networks and determines, via simulation, probabilities of both forward blocking and backward blocking. During light traffic load, any degradation in performance is due to backward blocking, whereas during heavy traffic load forward blocking dominates. In order to minimize performance degradation due to blocking, this paper proposes a token based routing scheme that is capable of searching for the availability of more than one route from source to destination, meeting the desired quality of service (QoS). Extensive simulation results show that the proposed technique significantly improves the blocking performance and setup delay.     

风电并网的若干问题研究

随着大规模风电场的建设,风电的并网问题日益凸显,本文从并网风电机组控制系统和电网建设方面进行分析,对并网所存在的问题及对策作了深入的探讨。     

Statistical Analysis of Multivariate Multiple Wavelength Liquid Chromatographic Response Data

Abstract

A standard mixture of uracil, phenol, benzaldehyde, and N,N-Diethyl-m-Toluamide was chromatographed under standard conditions at many wavelengths from 210 nm to 280 nm. the area percentage composition of the mixture varies depending on the wavelength chosen. Principal component analysis and factor analysis were done on the percent area composition data.     

Wavelength dispersive X-ray analysis and cathodoluminescence techniques for monitoring the chemical removal of AlInN on an N-face GaN surface

This paper shows the selective etching process of an AlInN sacrificial layer, lattice-matched to GaN, on N-face GaN by an aqueous solution of 1,2-diaminoethane. Using the wavelength dispersive X-ray (WDX) spectrometers on an electron probe micro-analyser, together with an optical spectrometer and silicon CCD array added to the light microscope, and sharing the same focus as the electron microscope, cathodoluminescence spectra are collected from exactly the same spot as sampled by the WDX spectrometers. This technique allows the compositional properties of the etched AlInN layer and the optical properties of the semiconductor layers underlying the sacrificial layer to be scrutinised, verifying the etching selectivity and the efficiency of the process.     

利用离轴腔增强吸收光谱技术探测实际大气中的二氧化碳

以1.573μm窄线宽可调谐半导体激光器作光源,结合高精细度光学谐振腔的离轴腔增强吸收光谱技术,选择CO2在6 357.311 6cm-1的吸收谱线,对实际大气CO2分子进行了测量。为了得到更准确的有效方程,对谐振腔吸收程长的标定方法进行了研究,给出了一种简单、实用的标定方法。实验结果表明,高精密度光学谐振腔的有效吸收程长为～1 195.73m,测得实际大气CO2的浓度为～388.3ppm(S/N≈22),最小可探测浓度为17.65ppm。将波长调制技术与OA-CEAS技术结合后,最终将CO2分子的最小可探测浓度提高到0.36ppm(S/N≈1 064)。     

A new alternative approach of all optical frequency encoded clocked S-R flip-flop exploiting the non-linear character of semiconductor optical amplifiers

In all optical networking and computing system, the role of all-optical flip-flops is very much essential. For signal synchronization with a reference clock and for storage of digital bits the flip-flop has no alternative. In this communication the authors propose a method of developing an all optical frequency encoded clocked R-S flip-flop using the non-linear character of semiconductor optical amplifiers. Frequency is the basic character of light and several encoding/decoding problems in computations and communications can be solved using the frequency encoding principle of optical data. The proposed system is all-optical and therefore it can extend a super fast speed of operation (far above THz limit).     

纳秒激光电离分子团簇产生高离化离子的激光波长效应

 利用脉冲分子束-激光电离-飞行时间质谱仪,在10⁹～10¹² W·cm^-2激光功率密度条件下,考察了Nd：YAG激光器输出的1 064,532,266 nm波长的激光与苯、氨、硫化氢等团簇的相互作用。发现1 064 nm的激光可以电离分子束产生高离化态的C⁴⁺,N⁵⁺,S⁶⁺等离子;波长为532 nm的激光则电离产生价态较低的C³⁺,C²⁺,N³⁺,N²⁺, S⁴⁺,S³⁺以及S²⁺ 等离子;在266 nm波长条件下进行实验,没有产生任何高价离子。提出了一个“多光子电离引发-逆轫致吸收加热-电子碰撞电离”模型来解释高价离子的产生。激光场下电子在团簇内部的逆轫致加热是整个过程的关键步骤,电子被加热的速度正比于激光波长的平方。这可以解释为何长波长的激光有利于更高价态离子的产生。     

纳秒强激光中乙腈团簇增强的高价电离研究

利用脉宽为25 ns的脉冲Nd∶YAG 1 064 nm的激光,在1010～1011 W·cm-2的强度下,用飞行时间质谱对乙腈分子束激光电离过程进行了研究。实验中利 用氦气作为载气,乙腈分子束采用扩散和脉冲两种方式进样,当扩散束进样时,乙腈分子的谱峰可用多光子电离来解释,而当脉冲分子束进样时,实验中产生了外层价电子高剥离的Nq+ (q=2～5) 和Cq+(q=1～4)信号谱。实验中同时发现,激光波长增大时,高价离子的谱强度也趋向于增大。激光延迟及谱峰的相关性分析表明,这些高价离子可能来源于乙腈团簇的库仑爆炸 过程。提出一个多光子电离引发,逆韧致吸收加热-电子碰撞电离模型来解释高价离子的产生,对高价离子伴随的波长效应也给出了较为合理的解释。