温度对CO光谱线吸收的影响分析

为了研究温度变化对CO吸收光谱线的影响,首先从吸收光谱原理出发,采用理论分析的方法,并利用高分辨率分子透射吸收数据库得出与温度有关的CO吸收光谱线谱线强度、综合加宽线型函数和吸收系数,然后通过MAT-LAB数值仿真出温度与CO吸收光谱线的谱线强度、综合加宽线型函数和吸收系数的变化关系曲线,并分析讨论温度与它们的关系。结果表明,温度对CO吸收光谱线的影响,特别是对综合加宽线型函数的影响是复杂的,并且不同激光频率还会影响线型函数和吸收系数随温度的变化关系,这对于实际应用中CO的吸收与测量具有重要的参考价值。     

基于混合卷积窗六谱线插值的多普勒信号处理

激光多普勒测速系统信号处理的过程中,通常采用快速傅里叶变换提取多普勒频移进而计算出被测物体运动速度,由于频谱泄露和栏栅效应的影响,会导致测量精度降低。本文提出了一种四项Nuttall窗和五项Rife Vincent窗的混合卷积窗函数结合改进的六谱线插值算法来降低频谱泄露和栏栅效应所带来的影响,从而提高激光多普勒信号处理精度。搭建了双光束后向散射差动式激光多普勒测速平台,通过仿真和实测得出在加入了RSN=-10dB的高斯白噪声的情况下使用该混合卷积窗所测量的最小相对误差为00027,而分别使用两个单一的窗函数测量的最小相对误差分别为00103和00461。从而验证了本方法的有效性。     

基于多波段混合气体吸收谱线的波长标定方法研究

为实现光纤扫描光源宽调谐范围内输出波长的高精度标定,提出了一种基于多波段混合气体吸收谱线的波长标定方法。采用分段阈值二阶导极值法和洛伦兹线型拟合法从混合气体吸收光谱中提取多条谱线中心位置,以其波长和驱动电压为参考点对Fabry-Perot(F-P)可调谐滤波器的迟滞非线性特性进行二次多项式拟合标定。将C2H2在C波段的吸收带与CO2在L波段的吸收带相结合,选取了21条C2H2谱线和16条CO2谱线作为波长参考。将本方法用于C+L波段的光纤光栅(FBG)波长解调,在0~60℃范围内波长拟合标准差小于3.3pm,线性相关系数大于0.999 8,系统稳定性误差小于2.6pm。     

Review on collision induced absorption in gases

A general view of spectroscopic phenomena of intermolecular collisions is presented together with the present directions of research in this field. A bibliography of about 600 references has been established, completing up to 1981 that of N.H. RICH and A.R.W. Mc KELLAR given in 1975.     

矢量正交频分复用系统的窄带干扰抑制

分析了窄带干扰对矢量正交频分复用(VOFDM)系统性能的影响,提出了一种VOFDM系统的窄带干扰抑制方法.该方法通过对接收矢量进行修正,把矢量子信道的接收转化为多载波码分多址(MC-CDMA)系统的接收检测问题,再采用最小均方误差合并技术实现窄带干扰抑制.性能分析及仿真结果表明,所建议的接收方法可有效提高系统对窄带干扰的顽健性,对于矢量长度为16的VOFDM,当信干比为15dB且误码率为10-2时,本方法相比于最小平方检测有约8dB的信噪比增益.     

Diffusion and absorption of corrosive gases in electronic encapsulants

Plastic encapsulated microcircuits with aluminum triple track structures were exposed to mixed flowing gas conditions to simulate and accelerate possible environments during long-term storage. No increase in resistance was measured and no corrosion products were observed after 800 h of accelerated exposure. Further experimentation indicated that chloride gas reacts with surface moisture in microscale and macroscale voids within the encapsulant, creating chloride ions. These ions become strongly bound to ion getters present in the epoxy molding compound, trapping the chloride ions within the bulk encapsulant and effectively retarding the diffusion process, which could lead to corrosion at the surface of the die.     

Support vector channel selection in BCI

Designing a brain computer interface (BCI) system one can choose from a variety of features that may be useful for classifying brain activity during a mental task. For the special case of classifying electroencephalogram (EEG) signals we propose the usage of the state of the art feature selection algorithms Recursive Feature Elimination and Zero-Norm Optimization which are based on the training of support vector machines (SVM). These algorithms can provide more accurate solutions than standard filter methods for feature selection. We adapt the methods for the purpose of selecting EEG channels. For a motor imagery paradigm we show that the number of used channels can be reduced significantly without increasing the classification error. The resulting best channels agree well with the expected underlying cortical activity patterns during the mental tasks. Furthermore we show how time dependent task specific information can be visualized.     

宽谱段环境污染气体红外遥测技术研究

根据环境污染气体监测的广谱需求,提出了宽谱段红外光谱遥测方法,利用长波红外傅里叶干涉光谱技术,向长波红外大气窗口短波端外扩展了仪器响应波段,使之在一定条件下能够探测多数常见工业气体的指纹特征。在7.0 ～14.5 m波段内,采用差谱法和亮温法,可监测多种常用工业有毒有害气体,并可给出以浓度程长积表征的概略浓度。介绍了遥测光谱仪的性能表征方法,例举了实用型产品PARES100对11种常用工业有毒有害气体的应用实例。     

浸入式光栅谱线特性

浸入式光栅常应用于光学材料折射率较高的红外谱段.其特殊的工作模式会产生一系列普通反射式光栅不需面临的问题, 而它们对于浸入式光栅的应用却十分重要.论文推导了普通光栅长波端与短波端谱线长度的关系.针对折射率与波长相关的特点, 以短波红外(1.5~2.5 μm)为例, 分析其谱线位置分布及光谱分辨率变化特性.结果表明, 浸入式光栅谱线分布相较于普通光栅有明显差异, “梯形”谱线会发生倾斜.在折射率变化较大的短波红外谱段, “梯形”谱线倾斜程度较明显.在以长波(2.5 μm)配准Littrow条件时, 谱线向短波端倾斜, 以短波(1.5 μm)配准时向长波端倾斜, 且Littrow波长均漂离中心波长.由于折射率在热红外谱段变化较小, “梯形”谱线倾斜较小, 更接近普通光栅情况.浸入式光栅的光谱分辨率随折射率变化而改变, 同级中, 波长增大分辨率增大;各级间, 级数减小分辨率减小.同时, 由于高级次(短波)分辨率大于低级次(长波), 因此各级谱线长度之比不再满足普通光栅中的比例关系.     

热像设备模数混合电路公共阻抗干扰的研究

随着红外成像技术的发展,大面阵探测器、高集成度处理电路、高帧频红外图像等特点给模拟电路的设计带来了很多困难,其中模数混合电路的干扰问题尤为突出.在建立电路模型的基础上对模拟前级的干扰问题形成原因进行了分析,依据分析结果改进设计模拟前级,经过验证,减小了模拟前级信号受到的干扰.     

氖原子弱光电流谱线的观测

应用光电流光谱技术,在空心阴极放电管中首次观测到氖原子的2P_7→4d_5、2P_1→4S_2 和2P_6→4d_J"跃迁产生的三条弱谱线.     

Combining Capon and APES for estimation of spectral lines

We propose combining the Capon and the APES spectral estimators for estimation of both the amplitude and the frequency of spectral lines. The so-obtained estimator does not suffer from Capon's biased amplitude estimates nor from APES' biased frequency estimates or resolution problem. Furthermore, the combined estimator is computationally simpler than APES and has about the same complexity as Capon. Numerical simulations are presented illustrating the increased performance.This work was supported in part by the Swedish Foundation for Strategic Research.     

Investigation of spectral dependences of the absorption coefficient in InGaAs layers

Journal of Communications Technology and Electronics - Values of the absorption coefficient of InGaAs structures grown by means of gaseous-phase epitaxy from metaloranic compounds have been studied...     

Equivalent network analysis of MIC transmission lines in the spectral domain

The propagation characteristics of planar guiding structures are analyzed by an equivalent network method in the spectral domain. Both the eigenvalues and eigenfunctions of the guided structure are determined by solving the active transmission line network. Numerical results obtained by the network method are compared with those obtained by the other method. It is demonstrated that the present method is simple but accurate and therefore is suitable for analyzing the 3-D discontinuity problems of some complicated planar structures.     

Widening of spectral lines in an Ar+laser

In this paper an investigation of the spectral line widths and shifts of Ar I and Ar II lines in argon ion laser plasma is carried out. The discharge-tube internal diameters were 5 and 7 mm, the current densities were 113, 163, and 242 A/cm², and the pressures were 0.68, 0.42, and 0.23 torr. Approximate calculations were made of ion and electron temperatures, electron density, ion mean free path, and charge-exchange cross section. It was determined that ion-neutral charge-exchange collisions play an important role in this type of plasma.     

红宝石激光诱导钠高离化态谱线

本文作者用高功率红宝石激光激发钠蒸汽，获得7条新的高离化态谱线，并证认其归属，实验结果与理论是一致的。     

Improved quasi-TEM spectral domain analysis of boxed coplanarmulticonductor microstrip lines

A very efficient quasi-TEM analysis of multistrip transmission systems embedded in a layered medium is presented. The number of conductors and substrates is arbitrary, and the whole structure is assumed to be enclosed in a rectangular set of boundary conditions. The analysis makes use of the Galerkin method in the spectral domain. Chebyshev polynomials with edge conditions are used as basis and test functions for the strips' free charge distribution. This standard technique is considerably enhanced by using two alternative procedures to accelerate the computation of the entries of the Galerkin matrix. Extremely accurate results for a multistrip system, including the charge distribution, can then be obtained on a PC computer in a short time     

On the family of ML spectral estimates for mixed spectrumidentification

A recently developed point spectrum identification procedure based on a family of AR and ML spectral estimates is exploited to arrive at a mixed spectrum identification procedure. To this end, a variety of properties of the AR and ML estimates as a function of model order are described. These properties relate to amplitude convergence, resolution and a characterization of the AR spectral artifact which is used to arrive at improved continuous spectral estimates. A variety of examples are presented     

基于光谱吸收CH4传感器灵敏度的分析

基于气体红外吸收的基本原理,首先对部分常见气体的吸收谱进行了解,然后对甲烷（CH4）气体传感器原理进行分析。对于光纤气体传感器而言,气体检测灵敏度是一个重要的考虑因素。通过对光谱吸收理论的分析和数据模拟,得到在不考虑光路干扰因素,理想状态情况下,气室吸收长度L和气体浓度C对传感器灵敏度的影响。当L一定时,C增大,则会提高传感灵敏度。当C一定时,增加L,尤其当C较高时,则传感灵敏度较高。