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rotational-ambiguity
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On rotational ambiguity in model-free analyses of multivariate data
, Article Journal of Chemometrics ; Volume 20, Issue 6-7 , 2006 , Pages 302-310 ; 08869383 (ISSN) ; Mason, C ; Tauler, R ; Jalali Heravi, M ; Maeder, M ; Sharif University of Technology
2006
Abstract
Rotational ambiguity is a central but not well investigated problem in all soft-modelling analyses of multivariate data. A novel method which is based on Resolving Factor Analysis (RFA) is proposed. Completely general and exhaustive results are presented for the two-component case. In particular the effects of noise and global analysis of series of measurements are investigated. Copyright © 2007 John Wiley & Sons, Ltd
Development and Application of Independent Component Analysis Method for Evaluation of Complex Chromatographic Data
, M.Sc. Thesis Sharif University of Technology ; Parastar Shahri, Hadi (Supervisor)
Abstract
In recent years, chromatographic technique as one of the most important analytical techniques have been developed for the analysis of complex samples. Hyphenated chromatographic techniques such as liquid or gas chromatography combine separation and spectroscopic detection technique to exploit the advantages of both and they have attracted attention of chemists to analyze complex mixtures. However, inadequate separation challenges still exist especially in the analysis of complex samples. Therefore, two-dimensional chromatographic systems such as comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) have been proposed for the analysis of complex samples due to their...
Development and Application of Chemometric Methods for Hyperspectral Image Analysis for Authentication and Adulteration Detection in Food (Saffron and Turmeric)
, Ph.D. Dissertation Sharif University of Technology ; Parastar Shahri, Hadi (Supervisor) ; Abdollahi, Hamid (Supervisor)
Abstract
The use of hyperspectral images to detect food fraud has become popular and it is necessary to develop chemometrics methods for analyzing the data from these images. Additionally, food authenticity has become a major challenge, and the focus of this thesis is on developing multivariate methods in chemometrics to extract useful information from data obtained from food authenticity verification using hyperspectral imaging (HSI). This thesis consists of six chapters. In the first chapter, a brief introduction to the fundamentals of hyperspectral imaging and food authenticity verification is presented. In the second chapter, the data structure of these images and chemometric methods including...
Mutual information map as a new way for exploring the independence of chemically meaningful solutions in two-component analytical data
, Article Analytica Chimica Acta ; Volume 1227 , 2022 ; 00032670 (ISSN) ; Abdollahi, H ; Tauler, R ; Rukebusch, C ; Parastar, H ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In the present contribution, a new approach based on mutual information (MI) is proposed for exploring the independence of feasible solutions in two component systems. Investigating how independent are different feasible solutions can be a way to bridge the gap between independent component analysis (ICA) and multivariate curve resolution (MCR) approaches and, to the best of our knowledge, has not been investigated before. For this purpose, different chromatographic and hyperspectral imaging (HSI) datasets were simulated, considering different noise levels and different degrees of overlap for two-component systems. Feasible solutions were then calculated by both grid search (GS) and...
Multivariate curve resolution-particle swarm optimization: A high-throughput approach to exploit pure information from multi-component hyphenated chromatographic signals
, Article Analytica Chimica Acta ; Volume 772 , 2013 , Pages 16-25 ; 00032670 (ISSN) ; Ebrahimi Najafabadi, H ; Jalali Heravi, M ; Sharif University of Technology
2013
Abstract
Multivariate curve resolution-particle swarm optimization (MCR-PSO) algorithm is proposed to exploit pure chromatographic and spectroscopic information from multi-component hyphenated chromatographic signals. This new MCR method is based on rotation of mathematically unique PCA solutions into the chemically meaningful MCR solutions. To obtain a proper rotation matrix, an objective function based on non-fulfillment of constraints is defined and is optimized using particle swarm optimization (PSO) algorithm. Initial values of rotation matrix are calculated using local rank analysis and heuristic evolving latent projection (HELP) method. The ability of MCR-PSO in resolving the chromatographic...
Is independent component analysis appropriate for multivariate resolution in analytical chemistry?
, Article TrAC - Trends in Analytical Chemistry ; Volume 31 , 2012 , Pages 134-143 ; 01659936 (ISSN) ; Jalali Heravi, M ; Tauler, R ; Sharif University of Technology
2012
Abstract
In this article, we examine Independent Component Analysis (ICA) and the concept of Mutual information (MI) as a quantitative measure of independence from the point of view of analytical chemistry. We compare results obtained by different ICA methods with results obtained by Multivariate Curve Resolution Alternating Least Squares (MCR-ALS). These results have shown that, when non-negativity constraints are applied, values of MI increase considerably and the resolved components cannot anymore be considered to be independent (i.e. they can only be considered to be the " least dependent" components). MI values of profiles resolved by MCR-ALS and ICA did not differ significantly when...
Joint approximate diagonalization of eigenmatrices as a high-throughput approach for analysis of hyphenated and comprehensive two-dimensional gas chromatographic data
, Article Journal of Chromatography A ; Volume 1524 , 2017 , Pages 188-201 ; 00219673 (ISSN) ; Parastar, H ; Sharif University of Technology
Abstract
The objective of the present work is development of joint approximate diagonalization of eigenmatrices (JADE) as a member of independent component analysis (ICA) family, for the analysis of gas chromatography-mass spectrometry (GC–MS) and comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC–MS) data to address incomplete separation problem occurred during the analysis of complex sample matrices. In this regard, simulated GC–MS and GC × GC–MS data sets with different number of components, different degree of overlap and noise were evaluated. In the case of simultaneous analysis of multiple samples, column-wise augmentation for GC–MS and column-wise super-augmentation...