【作者】 陈海秀；

【导师】 张国雄； 裘祖荣；

【作者基本信息】 天津大学 ， 测试计量技术及仪器， 2007， 博士

【摘要】 对液体的分析检测在环保、医药、食品、安检等行业都有重要的意义。随着人民生活水平的不断提高,人们对保护其生存环境的意识也日益增强,对污染的控制,对饮食、医药和工业用液的质量检测都提出了更多、更高的要求。运用先进的科学技术,研究建立实用、有效的分析方法和仪器已是势在必行。光谱液滴分析系统将光谱分析方法引入到液滴分析技术中来,对液体进行综合分析,在被测液体形成液滴的过程中,对被测液滴实施监测,从而获得有关该被测液体的物理、化学特性信息,对液体进行定性和量化识别。光谱液滴分析系统通过融合光谱分析技术和液滴分析技术,将光纤、电容液滴分析方法与小型光谱仪结合起来,既可以得到样品液滴在不同时刻的轮廓与电学、光学信息的关系,也可以同时得到该液体在设定波段的光谱信息,经过数据融合可得到由液体物理、化学及力学等特性综合确定的三维液滴指纹图。由于光纤、电容液滴分析方法对于某些液体来说不适用,在应用上存在一定的局限性。在这种情况下,利用光谱分析方法可帮助我们获取液体的特性信息。同时,在鉴别液体的应用中,对于液滴指纹信息比较相近的液体,可借助液体的光谱信息增强对液体的识别能力。反过来,对设定波段的小型光谱仪无法区分的样品,基于液滴指纹数据可以起到鉴别功能。对于液体中指定成分的定量分析,可借用红外光谱分析中的方法实现,此时需将小型光谱仪的工作波段设定在被测液体有吸收的波长范围内。光谱液滴分析方法将光谱分析的快速便捷与液滴分析的多参数结果的优点结合起来,使液滴分析技术进入到化学成分分析的领域,拓宽了液滴分析技术的应用范围。由于液体物理、化学特性的差异,从而不同液体在相同条件下形成液滴的轮廓形状不同,因此本文中还研究了图像液滴分析方法,不仅可以解决通过电容液滴分析方法获取液滴体积受液体介电常数影响的问题,而且更重要的意义是对液体的液滴几何轮廓特征进行分析,进一步研究利用了液体的力学特性。图像液滴分析方法可以单独使用,得到液体的液滴轮廓特征指纹图,同时也可以作为对其它液滴分析方法的一种补充。本文的主要工作和创造性研究包括以下几个方面:1.将光谱分析理论引入液滴分析,并通过技术融合搭建了一体化的测量仪器。选取工作波段在近红外光谱范围的小型光纤光谱仪用于系统中对液体样品的光谱分析,综合考虑仪器的实用性和结构耦合,设计了仪器的机械结构和光学结构,并对信号检测电路进行了改进设计,设计出整体结构小、便于在线分析的光谱液滴分析系统。2.在光谱测量中引入了流动比色装置,解决了对不同液体进行光谱测量时的条件一致性问题。由于液滴在生长过程中光程不断变化,直接通过液滴测量光谱时很难保证对不同液体具有相同的光程,从而给定量分析带来困难,而且由于液滴分析的特点与结构限制,使得直接通过液滴测量液体的吸收光谱难以实现,因此在测量装置中加入了流动比色装置,运用固定光程的样品池保证了光谱测量的一致性和可行性。3.运用光谱液滴分析系统,实现了对液体光谱信号和光纤、电容信号的同步采集,并通过数据融合,得到被测液体的三维液滴指纹图,它包含丰富的液体力学、物理、化学特性信息,从而为精确识别液体提供重要依据。4.运用CCD摄像机实时记录液滴的生长过程,并进行液滴图像分析,实现了液滴轮廓特征参数的提取和分析。利用液滴轮廓特征参数,可对液体进行鉴别分析。5.利用光谱液滴分析系统,对不同液体进行了实验分析,根据实验中得到的液体特征数据,建立液体样品特征数据库,实现对数据查询对照和对数据库中数据的管理操作,从而可对液体进行定性鉴别。6.结合化学计量学方法,实现了光谱数据预处理以及建模测算的定量分析模型的建立,从而可以对液体组分进行定量分析。通过对多组分液体的建模实验,验证了方法的可行性。更多还原

【Abstract】 The detection and analysis of liquid are significant in the fields such as environmental protection, medicine, food and safety inspection etc. With the improvement of living conditions, the consciousness of environmental protection is becoming stronger than ever. There are higher and higher requirements to the pollution control and quality detection of food, drink, medicine and industrial fluid. The research on practical and effective analytical methods and instruments based on advanced technology is an urgent demand. The spectral liquid signature analyzer introduces spectral analysis method into liquid analysis technology and studies the liquid sample synthetically. The physical and chemical property information of the liquid is acquired by monitoring the drop formation process under a certain measuring condition, and thus the qualitative and quantitative measurements and discrimination of liquids are realized.Through the merging of spectral analysis method and liquid analysis technology, the spectral liquid signature analyzer combines the fiber, capacitive drop analysis method with miniature spectrometer. The relationship between the sample liquid drop’s profile information at different time with the electrical and optical information of the liquid drop can be gained, as well as the spectral information of the liquid sample in the set waveband of miniature spectrometer. And after data merging the three-dimensional liquid fingerprints determined by the physical, chemical and mechanical properties of the liquid sample are available. As the fiber and capacitive liquid drop analysis are not suitable for some liquids and the application range is limited, the spectral method may be utilized to gain the character information of liquid in this condition. And in the application of liquid identification, for the liquid samples that can’t be distinguished with the set waveband miniature spectrometer, the discrimination function can be realized with the fingerprint data of the liquid drop. Moreover, for different liquids with similar fingerprint information, the discrimination ability can be also enhanced by spectrum information of liquids. The quantitative analysis of the specific component in liquid sample can be approached with the infrared spectrum analysis method, with the waveband of the miniature spectrometer be setted in the wavelength range in which the liquid sample has absorption phenomenon. The spectral liquid signature analysis method integrates the high speed, convenience of the spectrum analysis with the multifunction characteristics of liquid drop analysis. The application of spectral analysis makes it possible for research on the chemical composition of the liquid sample, which broadens the application fields of the liquid drop analysis technology.For the profile features of different liquid drops are different due to their physical and chemical characteristic differences, the image drop analysis method is also studied. With capacitance drop analysis method the drop volume obtained will be influced by the dielectric constant of the liquid. With the image drop analysis method this problem can be avoided, and more importantly this method can be used to analysis the liquid drop’s profile feature and to study the mechanical characteristics of the liquid. The image drop analysis method can be utilized solely and the profile characteristic fingerprints of the liquid drop are obtained. Moreover, the image drop analysis method can be as replenishment to other drop analysis methods.The dissertation covers the following aspects concerning the main work and creative researches.1. The spectral analysis theory is introduced to the liquid drop analysis technology and an integrated measuring instrument is developed through the technique merging. The near infrared miniature fiber spectrometer is applied in the system to acquire the spectrum of the liquid sample. Based on the consideration of structure coupling and the development of on-line analytical instrument, the mechanical and optical structures as well as signal processing circuit of the spectral liquid signature analyzer are designed.2. A flowing cuvette is introduced to the spectrum measuring part so as to solve the problem of consistency of the measurement condition for different liquid samples. During the drop formation process, the optical path changes with the growth of the drop. If the spectrum of the liquid sample were measured directly through the growing drop, it would be difficult to assure the same optical path length for different liquid samples, which would bring difficulty to quantitative analysis of liquid. The structure of the liquid drop analysis makes it impossible to measure the absorption spectrum directly through the liquid drop. Thus a flowing cuvette is utilized in the spectrum measurement, and the spectrum measurement of different liquid samples can be carried out with the fixed optical path length under the same conditions. 3. With the spectral liquid signature analyzer, the fiber, capacitive signal and the spectrum of the liquid sample can be captured simultaneously. The three-dimensional liquid fingerprints reflecting physical, chemical and mechanical properties of liquid are obtained after data processing. The fine discrimination between different liquid samples may be done with the integrated characteristics embodied in the three-dimensional fingerprints.4. The growing process of the liquid drop is recorded by a CCD camera, and the analysis of the liquid drop images is realized. The profile characteristic parameters of the liquid drop are extracted and can be used to discriminate different liquids.5. Experiments have been conducted with the spectral liquid signature analyzer, and a liquid database is established by using the liquid property data from the experiments. Data inquiry and other management operations to the database can be done with the application program, and the qualitative discrimination of liquid is realizable with the database.6. Chemometrics is applied to preprocess the spectroscopic data and to establish the quantitative analysis model. The feasibility of this method has been proved through the modeling the multi-component liquids.更多还原