Search results for "Partial least squares"
showing 10 items of 146 documents
Multivariate versus univariate calibration for nonlinear chemiluminescence data
2001
Abstract Multivariate calibration is tested as an alternative to model chromium(III) concentration versus chemiluminescence registers obtained from luminol-hydrogen peroxide reaction. The multivariate calibration approaches included have been: conventional linear methods (principal component regression (PCR) and partial least squares (PLS)), nonlinear methods (nonlinear variants and variants of locally weighted regression) and linear methods combined with variable selection performed in the original or in the transformed data (stepwise multiple linear regression procedure). Both the direct and inverse univariate approaches have been also tested. The use of a double logarithmic transformatio…
Semisupervised nonlinear feature extraction for image classification
2012
Feature extraction is of paramount importance for an accurate classification of remote sensing images. Techniques based on data transformations are widely used in this context. However, linear feature extraction algorithms, such as the principal component analysis and partial least squares, can address this problem in a suboptimal way because the data relations are often nonlinear. Kernel methods may alleviate this problem only when the structure of the data manifold is properly captured. However, this is difficult to achieve when small-size training sets are available. In these cases, exploiting the information contained in unlabeled samples together with the available training data can si…
Comparative Study of Several Machine Learning Algorithms for Classification of Unifloral Honeys
2021
Unifloral honeys are highly demanded by honey consumers, especially in Europe. To ensure that a honey belongs to a very appreciated botanical class, the classical methodology is palynological analysis to identify and count pollen grains. Highly trained personnel are needed to perform this task, which complicates the characterization of honey botanical origins. Organoleptic assessment of honey by expert personnel helps to confirm such classification. In this study, the ability of different machine learning (ML) algorithms to correctly classify seven types of Spanish honeys of single botanical origins (rosemary, citrus, lavender, sunflower, eucalyptus, heather and forest honeydew) was investi…
Detecting crop water status in mature olive orchards using vegetation spectral measurements.
2014
Full spectral measurements (350–2500 nm) at tree canopy and leaf levels and the corresponding leaf water potentials (LWP) were acquired in an olive grove of Sicily, at different hours of the day, during summer season 2011. The main objective of the work was to assess, on the basis of the experimental data-set, two different approaches to detect crop water status in terms of LWP. Specifically, using existing families of Vegetation Indices (VIs) and applying Partial Least Squares Regression (PLSR) were optimised and tested. The results indicated that a satisfactory estimation of LWP at tree canopy and leaf levels can be obtained using vegetation indices based on the near infrared–shortwave in…
Continuous 3-year outdoor operation of a flat-panel membrane photobioreactor to treat effluent from an anaerobic membrane bioreactor
2020
[EN] A membrane photobioreactor (MPBR) plant was operated continuously for 3 years to evaluate the separate effects of different factors, including: biomass and hydraulic retention times (BRT, HRT), light path (Lp), nitrification rate (NOxR), nutrient loading rates (NLR, PLR) and others. The overall effect of all these parameters which influence MPBR performance had not previously been assessed. The multivariate projection approach chosen for this study provided a good description of the collected data and facilitated their visualisation and interpretation. Forty variables used to control and assess MPBR performance were evaluated during three years of continuous outdoor operation by means …
Efeitos das práticas verdes na lealdade: proposta de um modelo para o segmento hoteleiro colombiano
2021
Resumen El propósito de este estudio fue analizar la incidencia de las prácticas verdes como impulsoras para generar confianza, satisfacción y lealtad en los huéspedes. Para ello, a partir de una muestra de 302 huéspedes de hoteles en Bogotá, Colombia, se estimó un modelo de ecuaciones estructurales a través de la regresión de mínimos cuadrados parciales. Los resultados obtenidos evidencian que las prácticas sostenibles contribuyen al aumento de la confianza y la satisfacción de los huéspedes, y que estas, a su vez, influyen positivamente en su lealtad hacia el hotel. Además, dichos resultados ponen de manifiesto que una comprensión más profunda del perfil de los turistas medioambientalment…
Fast and direct analysis of oxidation levels of oil-in-water emulsions using ATR-FTIR.
2019
International audience; Oxidation of omega-3 fatty acids is a major limitation on its enrichment in food and beverages. An efficient and simple method to monitor lipid oxidation in complex systems is essential to limit lipid oxidation during formulation and processing. Fish oil-in-water emulsions (20% v/v) were exposed to iron or free radical initiated oxidation. Conjugated dienes (CDs) were rapidly measured using a previously developed fat extraction method. Fourier transform infrared (FTIR) spectroscopy has been used to directly record chemical changes occurring during oxidation. Variations were noticed in different spectral regions despite the presence of broad water bands near 3400 and …
Consumer confidence: Causality links with subjective and objective information sources
2020
Abstract This study analyses the relationship of causality between consumer confidence and the economic information ecosystem from subjective (i.e., business sentiment) and objective sources (financial information from listed companies and the stock index). Our sample covers Spain from June 2011 to December 2018. Our results show that consumer confidence and economic information can exert a causality influence on each other. The results show Granger causality from IBEX35 and total assets in the financial sector and leverage of the companies in the energy sector to the consumer confidence index (CCI), in the first lag: from operating income in the telecommunications sector to the CCI in the …
Perceived Value in Tourism: A PLSPM Approach
2015
This paper examines the concept of perceived value in rural tourism referred to the specific context of Sicilian holiday farms. Herein main dimensions composing the rural tourist perceived value (RTPV) are discussed. Using Partial Least Squares Path Modelling (PLSPM) –a statistical technique especially suitable for exploratory purposes with small samples – a theoretical structural model of the multidimensional structure of RTPV is tested and the causal relationships among RTPV and its dimensions (Functional, Convenience, Emotional and Educational) and among RTPV and tourists’ satisfaction and loyalty are explored. Results from a field survey on 350 tourists give a contribution in terms of i…
Three-dimensional geometric morphometrics of thorax-pelvis covariation and its potential for predicting the thorax morphology: A case study on Kebara…
2020
The skeletal torso is a complex structure of outstanding importance in understanding human body shape evolution, but reconstruction usually entails an element of subjectivity as researchers apply their own anatomical expertise to the process. Among different fossil reconstruction methods, 3D geometric morphometric techniques have been increasingly used in the last decades. Two-block partial least squares analysis has shown great potential for predicting missing elements by exploiting the covariation between two structures (blocks) in a reference sample: one block can be predicted from the other one based on the strength of covariation between blocks. The first aim of this study is to test w…