The Application of SOM on Dioxin Fingerprint Matching

• Main Authors: Yu-Hsin Chang, 張宇欣
• Other Authors: 馬鴻文
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/11465123126965498405

碩士 === 國立臺灣大學 === 環境工程學研究所 === 95 === Nowadays, with fast development of industry in Taiwan, dioxin pollution events take place more often. The methods usually used for identifying pollution sources are bounded, and take a lot of time to analyze the results. To find out pollution sources effectively, a dioxin fingerprint matching model based on SOM Toolbox is built in this study. The half-lives of dioxin and the scenario of multiple pollution are also considered to investigate the influence of them on dioxin fingerprints. The main advantages of SOM dioxin fingerprint matching model are as follows: a) it is able to find out the dioxin pollution sources in the short time and from the limited information; b) by using U-matrix to visualize the SOM results, no other means are needed to help analyzing the topologies; c) there is no need to transform the variables to some linear functions, so that no information would be missed; and d) because of the concept of ‘neighborhood’, the spatial information of samples are displayed well. However, when there are more than two pollution sources, and the contribution of these sources are similar, SOM can’t identify exactly which the sources are. Moreover, the decay of dioxin in air, plants and soil doesn’t have any obvious influence on fingerprints, but it is the basis for judging whether there are only one or more than two pollution sources. On the other hand, the half-lives of dioxin in water and human blood are influential on fingerprints and may cause error of identifying pollution sources. As deduced from here, dioxin decay data and residence time in media both play very important roles in affecting the changes of dioxin fingerprints. As a result, the more local and complete decay data is gained, and the more specific the transportion of dioxin is known, the more accurate the dioxin fingerprint matching will be.