Design Of Data Acquisition System Of Scattering Light Signals From Atmospheric Particulate Matter

The single particle scattering method is widely employed due to its nonintrusive, fast, high precision and suitable for on- line measurement. In this dissertation, a particles measurement method based on the single particle light scattering method was studied and the corresponding scattered light signal acquisition system was designed. The main content and innovation achievements of this dissertation as follows:A particles measurement method based on the light scattering method, which simulates the scattering situation of the photons and single particle theory, to measure the information of particles was proposed. Two important theories were obtained through a large number of simulation calculations and analysis of scattering intensity spectrum curve of atmospheric particles under different circumstances. O ne is the particle diameter measurement model. —Regardless of the nature of particles, the scattering intensity only associated with the size of particles when the scattering angle is small. The other one is the particle nature(species) measurement model.—The scattering intensity of different composition particles processes great distinction in the wide-angle side. The near forward angle and three large angle are selected as °15 and °60, °135, °160.According to the above theory, the scattered light signal acquisition system was designed which mainly includes both hardware and software aspects. In terms of hardware, the light chamber structure of four channels and four corresponding photoelectric detection circuits were designed and the appropriate DAQ was selected. While for the software, data acquisition interface was written by using the Lab VIEW graphical programming software, including data collection, management, display and playback module to realize the real- time monitoring of the information from atmospheric particulate matter. During the process of designing the program, a login screen and print options and the design of access to the database and calling MATLAB were added. As a result, the system’s functions were extended and the further data processing was simplified. In order to test the stability of the system and the accuracy of data monitoring, some experiments have been done. From the test results, we can find that the acquisition system can collect data in real-time and complete the required acquisition tasks commendably.In this thesis, an overall data acquisition system of scattering light signals from atmospheric particle matter was designed. The theory achieved can be applied to collect the scattering light signals from atmospheric particle matter in real time. The method in this paper provides a valuable reference for the development of the atmospheric particulate matter detection analyzer.