基于红外光谱研究沥青燃烧机理和有害气体成分分析

利用Rosemount气体分析仪和定碳炉搭建起固定床燃烧反应试验平台,通过红外光谱分析技术定量分析沥青及其胶浆在高升温速率条件下燃烧反应的有毒气态产物成分、及其释放规律。研究表明,在高升温速率、近等温条件下,沥青及胶浆的燃烧过程可近似分为活泼挥发组分析出燃烧、二次挥发析出结合残炭燃烧两个阶段,其主要气态产物为CO₂,CO,NO,NO₂及SO₂。沥青材料中活泼挥发组分含量是影响燃烧气态产物释放规律的关键因素之一,减少沥青材料中活泼挥发组分的含量可有效降低燃烧气态产物的生成、尤其是CO的产生。     

多维漫透射光谱提高复杂混合溶液分析能力

多维漫透射光谱技术利用传统的近红外透射测量方式,增加一维扫描装置,获得透射方向上的径向光谱,并利用多点漫透射光谱对复杂混合溶液进行成分分析。实验设计了基于氙灯光源、精密电控平移台和光谱仪的检测装置,选用Intralipid-20%,India Ink和C₆H₁₂O₆共配制225种成分含量不同的混合溶液,分别测量距其透射中心点0～5 mm(间隔0.25 mm)范围内的20点漫透射光谱信号,以偏最小二乘回归算法对单点和多点漫透射光谱信号进行建模分析。实验得到India Ink含量和Intralipid-20%含量随漫透射光位置点的增加建模及预测的精度提高,C₆H₁₂O₆含量随漫透射光位置点的增加建模及预测精度没有明显变化。结果表明,增加不同位置信息的漫透射光谱信号,能够提高复杂混合溶液中强吸收物质和强散射物质的信噪比,对于弱吸收弱散射物质有望在提升系统精度的前提下提高其预测能力。     

利用同步荧光光谱快速鉴别潲水油

为快速鉴别潲水油,采用三维同步荧光光谱结合平行因子法解析潲水油的特征波长差(Δλ),并利用支持向量机建立潲水油鉴别模型。结果表明,潲水油的特征Δλ为60 nm;特征Δλ下的样品原始同步荧光光谱经过主成分分析提取5个主成分,以径向基函数(RBF)为核函数,利用网格搜索和6-fold交叉验证优化建模参数,得到惩罚因子C=512、核参数g=0.5,该条件下建立的模型对训练集和预测集的判别率均达到100%。采用同步荧光光谱可以快速、准确地鉴别潲水油。     

一种改进型多组分气体的Tikhonov正则化特征光谱提取方法

针对FTIR光谱分析数据计算量大,具有相同基团的多组分混合气体交叉灵敏度过高,以及在线分析过程中基线漂移等问题,提出了一种改进的TR2-1(Tikhonov 2norm-1norm)正则化特征变量提取法。该方法借鉴TR1和TR2模型的基本思想,引入谱线距离和谱线系数绝对值最小化两个约束项来保证所提取特征量的准确度,消除基线漂移所带来的影响,并结合上述两种模型建立了不适定问题的最优化求解通式。该通式有效地克服了经验法和实验法确定正则矩阵和参数所带来的误差。实验以浓度为0.01%~20%的甲烷、乙烷、丙烷、正丁烷、异丁烷、正戊烷和异戊烷气体为例进行了特征光谱选取。结果表明,对于浓度为0.2%的甲烷气体,其预测误差平方和仅为2.6×10-4,可决系数达到0.959 2,分析准确度高,有效增强了TR正则法的实用性。     

Mode-I crack in a two-dimensional fibre-reinforced generalized thermoelastic problem

A general model of the equations of the Lord-Şulman theory including one relaxation time and the Green-Lindsay theory with two relaxation times, as well as the classical dynamical coupled theory, are applied to the study of the influence of reinforcement on the total deformation for an infinite space weakened by a finite linear opening mode-I crack. We study the influence of reinforcement on the total deformation of rotating thermoelastic half-space and their interaction with each other. The material is homogeneous isotropic elastic half space. The crack is subjected to prescribed temperature and stress distributions. The normal mode analysis is used to obtain the exact expressions for displacement components, force stresses, and temperature. The variations of the considered variables with the horizontal distance are illustrated graphically. Comparisons are made with the results obtained in the three theories with and without rotation. A comparison is also made between the two theories for different depths.     

Holovideo: Real-time 3D range video encoding and decoding on GPU

We present a 3D video-encoding technique called Holovideo that is capable of encoding high-resolution 3D videos into standard 2D videos, and then decoding the 2D videos back into 3D rapidly without significant loss of quality. Due to the nature of the algorithm, 2D video compression such as JPEG encoding with QuickTime Run Length Encoding (QTRLE) can be applied with little quality loss, resulting in an effective way to store 3D video at very small file sizes. We found that under a compression ratio of 134:1, Holovideo to OBJ file format, the 3D geometry quality drops at a negligible level. Several sets of 3D videos were captured using a structured light scanner, compressed using the Holovideo codec, and then uncompressed and displayed to demonstrate the effectiveness of the codec. With the use of OpenGL Shaders (GLSL), the 3D video codec can encode and decode in realtime. We demonstrated that for a video size of 512×512, the decoding speed is 28 frames per second (FPS) with a laptop computer using an embedded NVIDIA GeForce 9400 m graphics processing unit (GPU). Encoding can be done with this same setup at 18 FPS, making this technology suitable for applications such as interactive 3D video games and 3D video conferencing.     

Detrended cross-correlation analysis of electroencephalogram

In the paper we use detrended cross-correlation analysis (DCCA) to study the electroencephalograms of healthy young subjects and healthy old subjects. It is found that the cross-correlation between different leads of a healthy young subject is larger than that of a healthy old subject. It was shown that the cross-correlation relationship decreases with the aging process and the phenomenon can help to diagnose whether the subject's brain function is healthy or not.     

空间调制傅里叶变换红外光谱仪多级微反射镜倾斜误差分析

空间调制傅里叶变换红外光谱仪无可动部件,系统稳定而紧凑,而且程差可控,可实现在线监测和实时检测。多级微反射镜是光谱仪干涉系统的关键器件,其在系统中的位置精度对光谱仪性能影响很大。本文对多级微反射镜的倾斜误差引起的光程差变化进行了理论计算,并利用光学软件进行了模拟仿真。分析结果表明,随着多级微反射镜倾斜角度的增大,干涉图对比度下降,对应的光谱图脉冲谱线展宽,信噪比下降,严重时会出现波数偏离。以上分析方法对后期系统公差分配及装调有着重要的指导意义。     

基于前失速先兆检测机理的叶顶喷气扩稳实验研究

拓宽轴流压气机稳定工作裕度及探索其流动失稳控制途径一直是内部流动研究的焦点。本文从前失速先兆检测机理入手,对前失速先兆与叶顶间隙泄漏流非定常性进行了关联性研究,发现了前失速先兆与叶顶间隙泄漏流非定常性有一定的关联性。在认识这类关联性的基础上,提出了基于前失速先兆捕捉的失稳控制途径,并结合DSP控制器构建扩稳控制方案,在低速轴流压气机上进行了实验验证。实验结果表明:采用叶顶喷气扩稳控制措施后,简化了原来复杂的控制机构,并为控制措施的实施预留了反馈控制时间,与原来的定常喷气控制措施相比有变工况自适应的优势。     

窗口可变滑动相关分析方法在激光诱导击穿光谱谱线自动识别中的应用

激光诱导击穿光谱(LIBS)谱线具有很窄的展宽,且光谱仪因外界温度条件的变化存在波长漂移,光谱数据为离散数字信号,受噪声、谱线重叠及连续背景的影响,信号存在失真和变形。而目前光谱仪自带谱线识别分析软件主要以"就近原则"为主,错误率较高,必须依赖于人眼的观察对比。针对这个问题,在研究LIBS光谱特性的基础上,提出了一种窗口可变滑动相关分析方法(CAASW),用于激光诱导击穿光谱谱线自动识别。以土壤标准物质为样品,对该方法进行了实验分析和评价,与光谱仪自带分析识别软件相比,CAASW明显提高了识别准确率和识别速度,最终实现了谱线的自动识别。