Design Of Small-sized Immersed Instrument Of COD Using Uy-vis Spectrophotometry

In this topic we designed a small-sized immersed instrument for measuring COD. The measuring principle was based on uv-vis spectrophotometry. With this method the instrument designed of the virtue of convenient operation, fast measuring, no secondary pollution to the environment and be able to on-line measurement. We choose xenon flash lamp as the illuminant, miniature fiber spectrometer served as the detector of transmission spectrum for water sample. Then, we design the measuring optical system, waterproof and sealed mechanical structure and measurement control circuit. Finally, the partial least-square (PLS), back propagation (BP) artificial neural network and radial basis function (RBF) artificial neural network algorithms are applied to modeling the relationship between COD and the spectra to find the best method.In the first chapter, we introduce the research background, recent research status and the content and purpose of this project; In the second chapter, we present the principle of uv spectrophotometry and give outlines of several normal methods of modeling the relationship between spectral and COD; In the third chapter, we introduce the optical design and mechanical design of the measuring optical system, the mechanical structure design of the whole instrument and the design of the measurement control circuit; In the fourth chapter, we employ the three methods mentioned in the second chapter to modeling the relationship between COD and the spectra, then use the model to predict and compare the advantages and disadvantages of the three kinds of methods; Finally, the main research contents of this topic was summarized and the future development was prospected.