| The atmosphere is very much polluted by various gases, among which sulfur dioxide is the most outrageous. It is known to all that sulfur dioxide produces acid rain of negative influence upon people's health, industry and agriculture. To put environmental pollution under control requires a constant keenness to concentration of sulfur dioxide in the atmosphere. Appropriate detection systems, that inform researchers of atmosphere quality in time, are supposed to established up in big cities. This is proved to be an effective way for the very purpose.Today, expensive as well as hard to maintain, instruments for detecting atmosphere quality are imported, which strains the proceeding of our research in this field. Prof. Yang Guanling, from Physic and telecom engineering school, South China Normal University, lead the project group to develop a project named "Domestic Research and Production of Atmosphere Auto-monitoring System". "Concentration Detection System of Sulfur Dioxide in the Atmosphere", is a part of the project. And Guang zhou Bureau of Environmental Protection supports the item.The thesis is based on other members' achievements in basic theories as well as fabrication of sample instruments for its smooth composition. A lot of helpful data really help a lot in the present work.Based on all work done by our members, the thesis makes a contrastive analysis of various principles and methods employed in detecting concentration of sulfur dioxide. Based on that ultra-violet fluorescence, theoretically, is able to function effectively in the detection, the invention of the monitoring instrument adopts virtual instruments and optic counting. The designing of all parts of the monitoring instrument is analyzed; running parameters are constantly in our mastery; all performance indexes of the instrument employed in the detection get ready for our research. The thesis emphasizes the key technologies. 1, In this paper, special attention is given to the theory of ultra-violetfluorescence and the detection of sulfur dioxide concentration in the atmosphere led by the former. The following formula is induced:Based on Lambert—Beer Law, the value of sic is small.2, Perfect the intelligent sample instrument and develop instrumental detection system that can run properly without the involvement of any virtual instrumental platform. The last system includes: the proposition of the best absorption spectrum; the designing of exciting light source; the further lowering of instrumental background counts; the designing of plate; the self detection of signals; the refrigeration of counting system and the display of temperature. Owning to the last list, the user can enjoy simple operation platform and the interaction between man and machine. As a part of the detection system of atmosphere quality, it takes into consideration systematization and the choice of instrumental network interface.3, The thesis completes the designing as well as debugging of software and hardware concerning light, machines, electricity and computation, figures out instrumental operation parameters.4, Acquire a lot of function parameter based on the instrument:(1) When the room temperature is 22°C ,the temperature of photon counter lowers to 5°C after 25 minutes.(2) The dark counter and background counter are stability. At the same time, the concentration of sample gas is constant, The response value is also bigger when the flow increases.(3) The concentration of sulfur dioxide is linear to photon counter when the counter gate is 1 second, the response value is 0.24counts/ppb · s. When the gate is 2s and 5s, the values increase to 0.51counts/ppb · s and 1.31counts/ppb · s. |
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