In view of the shortage of the former chemistry examination for coal mine gas it uses infrared spectrometry to monitor
gas, and propose the principle of surveying the coal mine gas basing on infrared absorption spectrum methods, and has
given the structure diagram of gas remote sensing alarm system. When infrared spectrum signal including the gas
information goes through the photoelectric detection, then it goes through the Fourier spectroscope to obtain the signal,
and does the enlargement transformation; at last the computer processes and recognizes the data. The theoretical analysis
and the experimental result indicate that after the signal pretreatment including characteristic extraction, background
deduction and normalized processing it obtains a standard standardized spectrum diagram. Based on gas member in
1.65μm absorption characteristic spectrum, when it is in before some background, the mine underground gas exists the
infrared radiation information that could change and arrive to the sensor, and then the alarm system can survey these
difference information and process it to confirm the gas density, when it is under certain threshold value the system will
alarm. Through the comparison, it retrieves the gas density in mine. This method has overcome the traditional method
such as gas chromatography hydrogen flame ionization detector with shortcoming of bad timeliness, has realized
complete non-contact online automatic monitor, and really reflected the gas density.
This paper introduces the principle and schematic diagram of gas monitoring system by means of infrared method. Annealing simulating algorithm is adopted to find the whole optimum solution and the Metroplis criterion is used to make iterative algorithm combination optimization by control parameter decreasing aiming at solving large-scale combination optimization problem. Experiment result obtained by the performing scheme of realizing algorithm training and flow of realizing algorithm training indicates that annealing simulating algorithm applied to identify gas is better than traditional linear local search method. It makes the algorithm iterate to the optimum value rapidly so that the quality of the solution is improved efficiently. The CPU time is shortened and the identifying rate of gas is increased. For the mines with much-gas gushing fatalness the regional danger and disaster advanced forecast can be realized. The reliability of coal-mine safety is improved.
The DOAS system is a synthetical system that combines optics mechanics electricity and computer technologies in it. The Multi-Path DOAS system that we developed is of great sensibility and lower measure limits. Advanced controlling and signal detection technology are applied in the system. This paper briefly summarizes the principle and the realization ofthe electrical control and signal detection in DOAS system
The DOAS technique is currently the developing trend and the main technique of online monitoring of tropospheric air quality measurements. In order to enlarge the scope of monitoring with only one set of instrument, we recently developed an multi-path LP-DOAS system in which we put several sets of retroreflectors at their own appointed remote places, each makes a measuring lightpath when the telescope aligns with it. In this way we can determine high spatial resolution and two or three-dimensional trace gas distributions of a larger region with the telescope as its center. We developed a stepping-motor-based mechanics-electrical device to drive the telescope. Under the control of a PC the telescope can automatically scan these retroreflectors one by one in continuous measure cycles.
In this paper, the developing of DOAS (Differential Optical Absorption Spectroscopy) in China is presented. The measurement campaigns were performed from November,2001 to February, 2002 in
Shanghai and from June, 2001 to April, 2002 in AIOFM (Ahhui Institute of Optical and Fine Mechanics) Hefei respectively to determine the concentration of SO<sub>2</sub>, NO<sub>2</sub> and O<sub>3</sub> in ambient air. For measuring the distribution of pollutants in troposphere, a new kink of DOAS system with high spatial and temporal resolution was developed under the cooperation between German and Chinese researcher. This work was described in the latest part of this paper.
The DOAS system is one that combine optics, mechanics, electricity and computer technologies in it. The long optical path DOAS system which we developed is of great sensibility and lower measure limits. It can get the concentration of several kind of trace gases in a given space region simultaneously in the same waveband. This paper provides the method of determining the correspond wavelength in the signal sampling and the method to calculate the delay time.