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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Algoritmo das projeções sucessivas para seleção de variáveis em calibração de segunda ordem

Gomes, Adriano de Araújo 29 June 2015 (has links)
Submitted by Maike Costa (maiksebas@gmail.com) on 2016-05-12T12:35:36Z No. of bitstreams: 1 arquivo total.pdf: 5933598 bytes, checksum: f90080e0529915a4c5c37308259bee89 (MD5) / Made available in DSpace on 2016-05-12T12:35:36Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 5933598 bytes, checksum: f90080e0529915a4c5c37308259bee89 (MD5) Previous issue date: 2015-06-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work it was developed a new strategy for intervals selection using the successive projections algorithm (SPA) coupled to N-PLS and U-PLS models, both with residual bilinearização (RBL) as a post-calibration step. The new algorithm coupled to N-PLS/RBL models was evaluated in two cases of studies. The first was simulated data for quantitation of two analytes (A and B) in the presence of a single interfering. On the second study was conducted a quantitation of ofloxacin in water in the presence of interferents (ciprofloxacin and danofloxacin) by means of liquid chromatography with diode array detection (LC-DAD) data modeling. The results were compared to the N-PLS/RBL model and the variables selection with the genetic algorithm (GA-N-PLS/RBL). In the first case of study (simulated data) were observed RMSEP values (x 10-3 in arbitrary units) for the analytes A and B in the order of 6.7 to 47.6; 10.6 to 11.4; and 6.0 to 14.0 for the N-PLS/RBL, Ga-N-PLS/RBL and the proposed method, respectively. On the second case of study (HPLC-DAD data) RMSEP value (mg/L) of 0.72 (N-PLS/RBL); 0.70 (GA-N-PLS/RBL) and 0.64 (iSPA N-PLS/RBL) were obtained. When combined with the U-PLS/RBL, the new algorithm was evaluated in the EEM modeling in the presence of inner filter effect. Simulated data and quantitation of phenylephrine in the presence of acetaminophen in water sample and interferences (ibuprofen and acetylsalicylic acid) were used as a case of studies. The results were compared to the U-PLS/RBL and e twell established method PARAFAC. For simulated data was observed the following RMSEP values (in arbitrary units) 1.584; 0.077 and 0.066 for PARAFAC; U-PLS/RBL and the proposed method, respectively. In the quantitation of phenylephrine the found RMSEP (in μg/L) were of 0.164 (PARAFAC); 0.089 (U-PLS/RBL) and 0.069 (ISPA-U-PLS/RBL). In all cases it was shown that variables selection is a useful tool capable of improving accuracy when compared with the respective global models (model without variables selection) leading to more parsimonious models. It was observed in all cases, that the sensitivity loss promoted by variables selection is compensated by using more selective channels, justifying the obtained RMSEP smaller values. Finally, it was also observed that the models based on variables selection such as the proposed method were free from significant bias at 95% confidence. / Neste trabalho foi desenvolvida uma nova estratégia para seleção de intervalos empregando o algoritmo das projeções sucessivas (SPA) acoplado a modelos N-PLS e U-PLS, ambos com etapa pós-calibração de bilinearização residual (RBL). O novo algoritmo acoplado a modelos N-PLS/RBL, foi avaliado em dois estudos de casos. O primeiro envolvendo dados simulados para quantificação de dois analitos (A e B) na presença de um único interferente. No segundo foi conduzida a quantificação de ofloxacina em água na presença de interferentes (ciprofloxacina e danofloxacina) por meio da modelagem de dados cromatografia liquida com detecção por arranjo de diodos (LC-DAD). Os resultados obtidos foram comparados ao modelo N-PLS/RBL e a seleção de variáveis com o algoritmo genético (GA-N-PLS/RBL). No primeiro estudo de caso (dados simulados) foram observados valores de RMSEP (x 10-3 em unidades arbitrárias) para os analitos A e B da ordem de 6,7 e 47,6; 10,6 e 11,4; 6,0 e 14,0 para o N-PLS/RBL, GA-N-PLS/RBL e o método proposto, respectivamente. No segundo estudo de caso (dados HPLC-DAD) valores de RMSEP (em mg/L) de 0,72 (N-PLS/RBL); 0,70 (GA-N-PLS/RBL) e 0,64 (iSPA-N-PLS/RBL) foram obtidos. Quando combinado com o U-PLS/RBL o novo algoritmo foi avaliado na modelagem de EEM em presença efeito de filtro interno. Dados simulados e a quantificação de fenilefrina na presença de paracetamol em amostras de água e interferentes (Ibuprofeno e ácido acetil salicílico) foram usados como estudos de caso. Os resultados obtidos foram comparados ao modelo U-PLS/RBL e ao bem estabelecido método PARAFAC. Para dados simulados foram observado os seguintes valores de RMSEP (em unidades arbitrarias) 1,584; 0,077 e 0,066 para o PARAFAC; U-PLS/RBL e método proposto, respectivamente. Na quantificação de fenilefrina os RMSEP (em μg/L) encontrados foram de 0,164 (PARAFAC); 0,089 (U-PLS/RBL) e 0,069 (iSPA-U-PLS/RBL). Em todos os casos foi demostrado que seleção de variáveis é uma ferramenta útil capaz de melhorar a acurácia quando comparados aos respectivos modelos globais (modelo sem seleção de variáveis) e tornar os modelos mais parcimoniosos. Foi observado ainda para todos os casos, que a perda de sensibilidade promovida pela seleção de variáveis é compensada pelo uso de canais mais seletivos, justificando os menores valores de RMSEP obtidos. E por fim, foi também observado que os modelos baseados em seleção de variáveis como o método proposto foram isentos de bias significativos a 95% de confiança.
2

Décomposition tensorielle de signaux luminescents émis par des biosenseurs bactériens pour l'identification de Systèmes Métaux-Bactéries / Tensor decomposition approach for identifying bacteria-metals systems

Caland, Fabrice 17 September 2013 (has links)
La disponibilité et la persistance à l'échelle locale des métaux lourds pourraient être critiques notamment pour l'usage futur des zones agricoles ou urbaines, au droit desquelles de nombreux sites industriels se sont installés dans le passé. La gestion de ces situations environnementales complexes nécessitent le développement de nouvelles méthodes d'analyse peu invasives (capteurs environnementaux), comme celles utilisant des biosenseurs bactériens, afin d'identifier et d'évaluer directement l'effet biologique et la disponibilité chimique des métaux. Ainsi dans ce travail de thèse, nous avons cherché à identifier, à l'aide d'outils mathématiques de l'algèbre multilinéaire, les réponses de senseurs bactériens fluorescents dans des conditions environnementales variées, qu'il s'agisse d'un stress engendré par la présence à forte dose d'un métal ou d'une carence nutritive engendrée par son absence. Cette identification est fondée sur l'analyse quantitative à l'échelle d'une population bactérienne de signaux multidimensionnels. Elle repose en particulier sur (i) l'acquisition de données spectrales (fluorescence) multi-variées sur des suspensions de biosenseurs multicolores interagissant avec des métaux et sur (ii) le développement d'algorithme de décomposition tensoriels. Les méthodes proposées, développées et utilisées dans ce travail s'efforcent d'identifier « sans a priori» a minima, la réponse fonctionnelle de biosenseurs sous différentes conditions environnementales, par des méthodes de décomposition de tenseurs sous contraintes des signaux spectraux observables. Elles tirent parti de la variabilité des réponses systémiques et permettent de déterminer les sources élémentaires identifiant le système et leur comportement en fonction des paramètres extérieurs. Elles sont inspirées des méthodes CP et PARALIND . L'avantage de ce type d'approche, par rapport aux approches classiques, est l'identification unique des réponses des biosenseurs sous de faibles contraintes. Le travail a consisté à développer des algorithmes efficaces de séparations de sources pour les signaux fluorescents émis par des senseurs bactériens, garantissant la séparabilité des sources fluorescentes et l'unicité de la décomposition. Le point original de la thèse est la prise en compte des contraintes liées à la physique des phénomènes analysés telles que (i) la parcimonie des coefficients de mélange ou la positivité des signaux source, afin de réduire au maximum l'usage d'a priori ou (ii) la détermination non empirique de l'ordre de la décomposition (nombre de sources). Cette posture a permis aussi d'améliorer l'identification en optimisant les mesures physiques par l'utilisation de spectres synchrones ou en apportant une diversité suffisante aux plans d'expériences. L'usage des spectres synchrones s'est avéré déterminant à la fois pour améliorer la séparation des sources de fluorescence, mais aussi pour augmenter le rapport signal sur bruit des biosenseurs les plus faibles. Cette méthode d'analyse spectrale originale permet d'élargir fortement la gamme chromatique des biosenseurs fluorescents multicolores utilisables simultanément. Enfin, une nouvelle méthode d'estimation de la concentration de polluants métalliques présents dans un échantillon à partir de la réponse spectrale d'un mélange de biosenseurs non-spécifiques a été développée / Availability and persistence of heavy metals could be critical for future use of agricultural or urban areas, on which many industrial sites have installed in the past. The management of these complex environmental situations requiring the development of new analytical methods minimally invasive, such as bacterial biosensors, to identify and directly assess the biological effects and the chemical availability of metals. The aims of this thesis was to identify the responses of fluorescent bacterial sensors various environmental conditions, using mathematical tools of algebra multi-linear, whether stress caused by the presence of high dose of a metal or a nutrient deficiency caused by his absence. This identification is based on quantitative analysis of multidimensional signals at the bacterial population-scale. It is based in particular on (i) the acquisition of multivariate spectral data on suspensions of multicolored biosensors interacting with metals and (ii) the development of algorithms for tensor decomposition. The proposed methods, developed and used in this study attempt to identify functional response of biosensors without \textsl{a priori} by decomposition of tensor containing the spectral signals. These methods take advantage of the variability of systemic responses and allow to determine the basic sources identifying the system and their behavior to external factors. They are inspired by the CP and PARALIND methods. The advantage of this approach, compared to conventional approaches, is the unique identification of the responses of biosensors at low constraints. The work was to develop efficient algorithms for the source separation of fluorescent signals emitted by bacterial sensors, ensuring the sources separability and the uniqueness of the decomposition. The original point of this thesis is the consideration of the physical constraints of analyzed phenomena such as (i) the sparsity of mixing coefficients or positivity of sources signals in order to minimize the use of a priori or (ii) the non-empirical determination of the order of decomposition (number of sources).This posture has also improved the identification optimizing physical measurements by the use of synchronous spectra or providing sufficient diversity in design of experiments. The use of synchronous spectra proved crucial both to improve the separation of fluorescent sources, but also to increase the signal to noise ratio of the lowest biosensors. This original method of spectral analysis can greatly expand the color range of multicolored fluorescent biosensors used simultaneously. Finally, a new method of estimating the concentration of metal pollutants present in a sample from the spectral response of a mixture of non-specific biosensor was developed

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