title: Prediction of the distillation temperatures of crude oils using ¹H NMR and support vector regression with estimated confidence intervals.
abstract: This paper aims to estimate the temperature equivalent to 10% (T10%), 50% (T50%) and 90% (T90%) of distilled volume in crude oils using (1)H NMR and support vector regression (SVR). Confidence intervals for the predicted values were calculated using a boosting-type ensemble method in a procedure called ensemble support vector regression (eSVR). The estimated confidence intervals obtained by eSVR were compared with previously accepted calculations from partial least squares (PLS) models and a boosting-type ensemble applied in the PLS method (ePLS). By using the proposed boosting strategy, it was possible to identify outliers in the T10% property dataset. The eSVR procedure improved the accuracy of the distillation temperature predictions in relation to standard PLS, ePLS and SVR. For T10%, a root mean square error of prediction (RMSEP) of 11.6°C was obtained in comparison with 15.6°C for PLS, 15.1°C for ePLS and 28.4°C for SVR. The RMSEPs for T50% were 24.2°C, 23.4°C, 22.8°C and 14.4°C for PLS, ePLS, SVR and eSVR, respectively. For T90%, the values of RMSEP were 39.0°C, 39.9°C and 39.9°C for PLS, ePLS, SVR and eSVR, respectively. The confidence intervals calculated by the proposed boosting methodology presented acceptable values for the three properties analyzed; however, they were lower than those calculated by the standard methodology for PLS.
authors.affiliation: Institute of Chemistry, State University of Campinas, POB: 6154, 13084-971 Campinas, Brazil.
authors.forename: Paulo R
authors.initials: PR
authors.lastname: Filgueiras
authors.affiliation: Institute of Chemistry, State University of Campinas, POB: 6154, 13084-971 Campinas, Brazil.
authors.forename: Luciana A
authors.initials: LA
authors.lastname: Terra
authors.affiliation: Department of Chemistry, Federal University of Espírito Santo, Laboratory of Research and Development of Methodologies for Analysis of Oils, Avenida Fernando Ferrari 514, Goiabeiras, Vitória 29075-910, Espírito Santo, Brazil.
authors.forename: Eustáquio V R
authors.initials: EV
authors.lastname: Castro
authors.affiliation: CENPES/PETROBRAS, Avenida Jequitiba 950, Rio de Janeiro 21941-598, Brazil.
authors.forename: Lize M S L
authors.initials: LM
authors.lastname: Oliveira
authors.affiliation: CENPES/PETROBRAS, Avenida Jequitiba 950, Rio de Janeiro 21941-598, Brazil.
authors.forename: Júlio C M
authors.initials: JC
authors.lastname: Dias
authors.affiliation: Institute of Chemistry, State University of Campinas, POB: 6154, 13084-971 Campinas, Brazil. Electronic address: ronei@iqm.unicamp.br.
authors.forename: Ronei J
authors.initials: RJ
authors.lastname: Poppi
keywords: Boosting; Confidence interval; Crude oil; Distillation boiling point; Partial least squares; Support vector regression