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To evaluate the multidimensional measurement derived from the gas sensors array, dimensionality reduction was performed using the t-SNE method, which (unlike the commonly used PCA method) preserves the local structure of the data by minimizing the Kullback-Leibler divergence between the two distributions with respect to the location of points on the map. The k-median method was used to evaluate the discretization potential of the collected multidimensional data. It showed that observations from different stages of the wastewater treatment process have varying chemical fingerprints. In the final stage of data analysis, a supervised machine learning method, in the form of a random forest, was used to classify observations based on the measurements from the sensors array. The quality of the resulting model was assessed based on several measures commonly used in classification tasks. All the measures used confirmed that the classification model perfectly assigned classes to the observations from the test set, which also confirmed the absence of model overfitting.<\/jats:p>","DOI":"10.3390\/s23010487","type":"journal-article","created":{"date-parts":[[2023,1,2]],"date-time":"2023-01-02T04:51:22Z","timestamp":1672635082000},"page":"487","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":42,"title":["Application of Machine Learning Methods for an Analysis of E-Nose Multidimensional Signals in Wastewater Treatment"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6531-6562","authenticated-orcid":false,"given":"Magdalena","family":"Pi\u0142at-Ro\u017cek","sequence":"first","affiliation":[{"name":"Faculty of Technology Fundamentals, Lublin University of Technology, 20-618 Lublin, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2415-7454","authenticated-orcid":false,"given":"Ewa","family":"\u0141azuka","sequence":"additional","affiliation":[{"name":"Faculty of Technology Fundamentals, Lublin University of Technology, 20-618 Lublin, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0035-7187","authenticated-orcid":false,"given":"Dariusz","family":"Majerek","sequence":"additional","affiliation":[{"name":"Faculty of Technology Fundamentals, Lublin University of Technology, 20-618 Lublin, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0559-5475","authenticated-orcid":false,"given":"Bartosz","family":"Szel\u0105g","sequence":"additional","affiliation":[{"name":"Faculty of Environmental, Geomatic and Energy Engineering, Kielce University of Technology, 25-314 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9092-9854","authenticated-orcid":false,"given":"Sylwia","family":"Duda-Saternus","sequence":"additional","affiliation":[{"name":"Institute of Rural Health in Lublin, 20-090 Lublin, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0621-7222","authenticated-orcid":false,"given":"Grzegorz","family":"\u0141ag\u00f3d","sequence":"additional","affiliation":[{"name":"Faculty of Environmental Engineering, Lublin University of Technology, 20-618 Lublin, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1389","DOI":"10.1016\/j.watres.2006.01.034","article-title":"Evolution of a Wastewater Treatment Plant Challenges Traditional Design Concepts","volume":"40","author":"Dominguez","year":"2006","journal-title":"Water Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"134","DOI":"10.5004\/dwt.2020.25439","article-title":"Simulation of the Influence of Wastewater Quality Indicators and Operating Parameters of a Bioreactor on the Variability of Nitrogen in Outflow and Bulking of Sludge: Data Mining Approach","volume":"186","year":"2020","journal-title":"Desalin. 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