Carmine is a widely used food pigment in various food and beverage additives. Excessive consumption of synthetic pigment shall do harm to body seriously. The food is generally associated with a variety of colors. Under the simulation context of various food pigments’ coexistence, we adopted the technology of fluorescence spectroscopy, together with the PSO-SVM algorithm, so that to establish a method for the determination of carmine content in mixed solution. After analyzing the prediction results of PSO-SVM, we collected a bunch of data: the carmine average recovery rate was 100.84%, the root mean square error of prediction (RMSEP) for 1.03e-04, 0.999 for the correlation coefficient between the model output and the real value of the forecast. Compared with the prediction results of reverse transmission, the correlation coefficient of PSO-SVM was 2.7% higher, the average recovery rate for 0.6%, and the root mean square error was nearly one order of magnitude lower. According to the analysis results, it can effectively avoid the interference caused by pigment with the combination of the fluorescence spectrum technique and PSO-SVM, accurately determining the content of carmine in mixed solution with an effect better than that of BP.
In this paper, a sylstem of fiber-optic gas sensor based methane absorption spectra is studied. The system have made
great improvement and in-depth analysis in methane spectral absorption,a weak optical signal extraction and processing
and gas measurement accuracy.The system consists of light source, Photonic Crystal Fiber, air chamber, photoelectric
detectors and signal processing components and so on. According to the Lambert-Beer law, spectrum absorption
intensity is closely relate with the concentration of the gas. In order to ensure the system at a high resolution and
sensitivity,The system used distributed feedback semiconductor laser (DFBLD) as a light source .It bring useful
information of the optical signal to PIN Photodetector which then convert the optical signal to electrical signals after
optical interacting with the methane gas,then send the electrical signal to lock-in amplifier.the harmonic detection of
gas concentration was achieved by the light modulator, And then compared the harmonic component. Finally, the signal
expected was produced through the A / D converter digital in the computer.
An optical fiber gas sensing system based on the law of Beer-Lambert is designed to determine the concentration of gas.
This technique relies on the fact that the target gas has a unique, well-defined absorption characteristic within the
infrared region of electromagnetic spectrum. The narrow-band filtering characteristic of optical fiber Bragg grating is
used to produce the narrow spectrum light signal. An aspheric objective optical fiber collimator is used in the system as
an optical fiber gas sensing detector to improve the sensitivity and stability. Experimental results show there is a high
measuring sensitivity at 0.01%, and the measuring range goes beyond 5%.
Methane is the main composition of natural gas and marsh gas. It is an important industrial raw material and combustion gas in daily life. Detecting methane and its concentration in time has utmost important affect on safe operation of industry mine and person safe. Developing methane-detecting system has become an important topic and research direction of gas detecting domain. Through processing weak signal with harmonic detection technique, a multi-point fiber-optic gas sensor system for measuring the concentration of methane is designed based on light absorbing capability of gas, which varies with gas concentration at its characteristic wavelength. DFBLD (Distributed Feedback Laser Diode) in 1300nm waveband is used as illuminant and phase-detecting technology is used to carry out harmonic wave detecting the concentration of methane. Study shows that the accuracy of instrument is 5ppm, accuracy and stability of the sensor can meet practical demands. It can be applied to multi-point measurement at real-time in multiple occasions.