Search results for " PCA"

Nonlinear data description with Principal Polynomial Analysis

2012

Principal Component Analysis (PCA) has been widely used for manifold description and dimensionality reduction. Performance of PCA is however hampered when data exhibits nonlinear feature relations. In this work, we propose a new framework for manifold learning based on the use of a sequence of Principal Polynomials that capture the eventually nonlinear nature of the data. The proposed Principal Polynomial Analysis (PPA) is shown to generalize PCA. Unlike recently proposed nonlinear methods (e.g. spectral/kernel methods and projection pursuit techniques, neural networks), PPA features are easily interpretable and the method leads to a fully invertible transform, which is a desirable property…

Integrated analytical methodologies for the non-invasive study of Cultural Heritage: the case study of Renaissance Statues of Abatellis Palace

2012

Polychlorinated Biphenyls in Sediments from Sicilian Coastal Area (Scoglitti) using Automated Soxhlet, GC-MS, and Principal Component Analysis

2014

A methodology for the PAHs and PCBs congener determination in sediment samples has been revised. We determined the distributions of PAHs and PCBs in the superficial sediments of the Scoglitti (Italy) coastal area to provide data for comparison with other marine systems and to hypothesize the sources. Extraction yield, for PCB, was never less than 60% in most cases, while for PAHs, utilizing perdeuterated surrogate standard (benz[a]anthracene-d12 and anthracene-d10) was never less than 72%. The total concentration of the 16 PAHs investigated, expressed as the sum of concentrations, PAHs, varied from 1–5087 μg/kg of dry matrix, while the PCBs ranged from detection limit to 36 μg/kg of dry mat…

Spettrofotometria per il monitoraggio degli interventi di restauro: valutazione tramite PCA

2011

La realizzazione di indagini spettrofotometriche per il monitoraggio delle variazioni cromatiche pone la necessità di gestire un elevato numero di dati richiedendo l’utilizzo di analisi statistiche. A tale scopo, la PCA è stata applicata a dati spettrofotometrici relativi a diverse tipologie di superfici (musive, marmoree, etc). Tale metodologia permette di valutare in maniera efficace gli effetti generati a seguito del restau;ro, evidenziando la correlazione tra tutte variabili spettrofotometriche. La distribuzione in cluster dei dati consente di visualizzare la variabile che maggiormente contribuisce allo spostamento cromatico, permettendo il monitoraggio differenziato del comportamento d…

Agronomical and chemical characterisation of Thymbra capitata (L.) Cav. biotypes from Sicily, Italy

2015

In this study the agromomical and chemical characterization of 13 sicilian biotypes of Thymbra capitata (L.) Cav. (or Thymus capitatus Hoff. et Link.) collected from different areas of Sicily (Italy) and grown under the same agricultural and environmental condition are reported. The main morpho-productive parameters and quali-quantitative profile of essential oils were determined . Essential oils were extracts from the aerial parts of the plants by hydrodistillation. The essential oils were analyzed by GC-FID and GC-MS. Hierarchical Cluster Analysis and Principal Component Analysis statistical methods were used to group biotypes according to the essential oils chemical composition. The esse…

Reuse of Food Waste: The Chemical Composition and Health Properties of Pomelo (Citrus maxima) Cultivar Essential Oils

2022

The aim of the present study is to investigate the chemical profile, antioxidant activity, carbohydrate-hydrolysing enzyme inhibition, and hypolipidemic effect of essential oils (EOs) extracted from Sicilian Citrus maxima (pomelo) flavedo. Using gas-chromatography-mass spectrometry analysis (GC-MS) we analysed the Eos of five cultivars of C. maxima, namely, ‘Chadock’, ‘Maxima’, ‘Pyriformis’, ‘Terracciani’, and ‘Todarii’, and their blends. The antioxidant activity was performed by using a multi-target approach using 2,2′-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic acid (ABTS), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), ferric reduc…

Multiple factor analysis: principal component analysis for multitable and multiblock data sets

2013

On application of kernel PCA for generating stimulus features for fMRI during continuous music listening

2018

Background There has been growing interest towards naturalistic neuroimaging experiments, which deepen our understanding of how human brain processes and integrates incoming streams of multifaceted sensory information, as commonly occurs in real world. Music is a good example of such complex continuous phenomenon. In a few recent fMRI studies examining neural correlates of music in continuous listening settings, multiple perceptual attributes of music stimulus were represented by a set of high-level features, produced as the linear combination of the acoustic descriptors computationally extracted from the stimulus audio. New method fMRI data from naturalistic music listening experiment were…

Determination of Changes in the Quality of Surface Water in the River—Reservoir System

2021

Assessing the changing parameters of water quality at different points in the river–reservoir system can help prevent river pollution and implement remedial policies. It is also crucial in modeling water resources. Multivariate statistical analysis is useful for the analysis of changes in surface water quality. It helps to identify indicators that may be responsible for the eutrophication process of a reservoir. Additionally, the analysis of the water quality profile and the water quality index (WQI) is useful in assessing water pollution. These tools can support and verify the results of a multivariate statistical analysis. In this study, changes in water quality parameters of the Turawa r…

Improved chemometric approach for XRF data treatment: application to the reverse glass paintings from the Lipari collection

2023

The Aeolian cultural heritage preserves hundreds of testimonies of the past that have passed through six millennia of history. Among these, the Archeological Park of the Aeolian Islands with the Museum Luigi Bernab`o Brea (Italy) preserves a valuable set of artworks, which are related to a little-known ‘popular’ figurative heritage. It is an assemblage of small glass foils decorated using the technique of reverse painting, datable to between the end of the 17th century and the end of the 18th century, and actually under investigation by historians. Here, an X-ray fluorescence (XRF) spectroscopy study (performed with portable equipment) is combined with a multivariate approach that allows us…