Algoritmo genético em química

Filho, Paulo Augusto da Costa; Poppi, Ronei J.

doi:10.1590/s0100-40421999000300019

Cited by 13 publications

(15 citation statements)

References 11 publications

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“…It is important to notice that genetic algorithms do not require an initial guess for the parameters to be fitted, as they involve the generation of random sets of parameters throughout all the considered space. Although the result can not be the exact minimum of a function, the convergence goes necessarily towards the global minimum, and not towards local minima 21. Therefore, the chosen strategy consisted of using the values obtained by the genetic algorithm as initial guesses for the Powell method.…”

Section: Methodologies and Resultsmentioning

confidence: 99%

Synthesis of telechelic C₆₀ end‐capped polymers under microwave irradiation

Lin

et al. 2005

J of Applied Polymer Sci

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Bromo-Double-Terminated polystyrene (BrPSt-Br) and poly(methyl methacrylate) (Br-PMMA-Br) with predesigned molecular weight and narrow polydispersity were prepared by atom transfer radical polymerization (ATRP) using the initiating system aaЈ-dibromo-p-xylene(DBX) / CuBr/2,2Ј-bipyridine(bipy). The precursor bromo-terminated polymers were subsequently functionalized with fullerene C 60 using CuBr/bipy as the catalyst system under microwave irradiation (MI). The telechelic C 60 endcapped products were characterized by gel permeation chromatography (GPC), UV-vis, FT-IR, TGA, DSC, 1 H NMR, and 13 C NMR. The results showed that microwave irradiation could significantly increase the rate of fullerenation reaction, and the physical properties and structure of the C 60 endcapped polymers are not modified by the use of the microwave.

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Section: Methodologies and Resultsmentioning

confidence: 99%

Synthesis of telechelic C₆₀ end‐capped polymers under microwave irradiation

Lin

et al. 2005

J of Applied Polymer Sci

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“…The starting point for the use of GA is the mathematical representation of the problem. After coding, the algorithm is initialized and searches, iteratively, optimal points inside the sample domain. , …”

Section: Methodsmentioning

confidence: 99%

“…For vibrational spectroscopy, each spectrum is treated as being composed of a set of genes (wavenumbers, for example) that are arranged in a binary code. Each variable or wavenumber can receive the binary encoding 1 (selected) or 0 (not selected). , The original chromosome is randomly disturbed, creating several chromosomes from the initial population. The response for each chromosome, associated with the corresponding experimental conditions, is evaluated.…”

Section: Methodsmentioning

confidence: 99%

“…The existing variable selection methods differ by the procedure performed for selection of the spectral region. Among the methods currently used, we highlight interval partial least squares (iPLS), , elimination of uninformative variables in partial least squares (UVE-PLS), and genetic algorithm (GA) . The variable selection technique allows the elimination of unimportant information like, for example, infrared bands that do not contain any information on the properties to be analyzed or that have significant signal-to-noise amplitude …”

Section: Introductionmentioning

confidence: 99%

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Sulfur Determination in Brazilian Petroleum Fractions by Mid-infrared and Near-infrared Spectroscopy and Partial Least Squares Associated with Variable Selection Methods

et al. 2016

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Chemometric tools (PLS) with variable selection (iPLS, siPLS, UVE and GA), associated with near infrared (NIR) and mid infrared (MIR) spectroscopy, were applied for the determination of sulfur content (wt %) in petroleum derivatives. The evaluation of the models was conducted by the determination and analysis of the following requirements: coefficient of determination (R 2 ); the curve obtained by plotting the predicted versus measured values; and also the cross-validation and prediction errors.The developed models presented in this work had satisfactory results, demonstrating that both NIR and MIR techniques, combined with chemometric tools, can be used to determine the sulfur content in petroleum fractions, with LOD and LOQ from 0.0234 and 0.0781 respectively. All variable selection techniques improved the predictive ability of the mode when compared with the full-spectra model, except the UVE method that showed a better performance only when associated with MIR data.

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“…Este método poderia ser usado, por exemplo, na seleção de variáveis de dados espectroscópicos em calibração multivariada [97][98][99] .…”

Section: Aplicação De Efa E Simplisma Em Análise De Solosunclassified

Avaliação do uso de métodos quimiométricos em análise de solos

Sena¹,

Poppi²,

Frighetto³

et al. 2000

Quím. Nova

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EVALUATION OF THE USE OF CHEMOMETRIC METHODS IN SOIL ANALYSIS. One of the major interests in soil analysis is the evaluation of its chemical, physical and biological parameters, which are indicators of soil quality (the most important is the organic matter).Besides there is a great interest in the study of humic substances and on the assessment of pollutants, such as pesticides and heavy metals, in soils. Chemometrics is a powerful tool to deal with these problems and can help soil researchers to extract much more information from their data. In spite of this, the presence of these kinds of strategies in the literature has obtained projection only recently. The utilization of chemometric methods in soil analysis is evaluated in this article. The applications will be divided in four parts (with emphasis in the first two): (i) descriptive and exploratory methods based on Principal Component Analysis (PCA); (ii) multivariate calibration methods (MLR, PCR and PLS); (iii) methods such as Evolving Factor Analysis and SIMPLISMA; and (iv) artificial intelligence methods, such as Artificial Neural Networks.Keywords: chemometrics; soil analysis; principal component analysis. DIVULGAÇÃO INTRODUÇÃOCom a crescente sofisticação das técnicas instrumentais de análise química, impulsionada pela invasão de microprocessadores e microcomputadores no laboratório, técnicas de tratamentos de dados mais complexas do ponto de vista matemáti-co e estatístico tornaram-se necessárias 1 . A análise de dados é uma parte essencial em todo experimento, sendo univariada quando somente uma variável é medida sistematicamente para várias amostras. Há muito tempo a estatística univariada vem sendo aplicada a problemas químicos, mas a sua utilização tornou-se limitada. Nas últimas décadas, a aná-lise multivariada foi introduzida no tratamento de dados quími-cos, ganhando rapidamente popularidade e dando origem a uma nova disciplina, batizada de Quimiometria. O modelo estatístico dos métodos multivariados considera a correlação entre muitas variáveis analisadas simultaneamente, permitindo a extração de uma quantidade muito maior de informação.Neste artigo será avaliada a utilização de métodos quimiométricos em análise de solos. O solo é uma estrutura complexa formada pela influência de fatores geológicos, topográficos, climáticos, temporais e antropogênicos; sendo a parte mais importante da geosfera e de onde provêm a maior parte dos nossos alimentos. Além disso, ele funciona como uma espécie de filtro ambiental para a purificação da água e do ar 2 . O interesse maior na análise de solos está na avaliação de seus parâmetros químicos (concentração de metais e nutrientes, pH, etc.), físicos (compactação, umidade, etc.) e biológicos (microrganismos, etc.), os quais são um indicador de sua qualidade. Dentre os constituintes do solo, o mais estudado é a matéria orgânica (MO). Esta controla muitas de suas propriedades e é um fator central na manutenção de sistemas agrícolas sustentá-veis. Práticas que favoreçam a conservação da MO melhoram as propriedades ...

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Algoritmo genético em química

Cited by 13 publications

References 11 publications

Synthesis of telechelic C₆₀ end‐capped polymers under microwave irradiation

Synthesis of telechelic C₆₀ end‐capped polymers under microwave irradiation

Sulfur Determination in Brazilian Petroleum Fractions by Mid-infrared and Near-infrared Spectroscopy and Partial Least Squares Associated with Variable Selection Methods

Avaliação do uso de métodos quimiométricos em análise de solos

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Algoritmo genético em química

Cited by 13 publications

References 11 publications

Synthesis of telechelic C60 end‐capped polymers under microwave irradiation

Synthesis of telechelic C60 end‐capped polymers under microwave irradiation

Sulfur Determination in Brazilian Petroleum Fractions by Mid-infrared and Near-infrared Spectroscopy and Partial Least Squares Associated with Variable Selection Methods

Avaliação do uso de métodos quimiométricos em análise de solos

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Synthesis of telechelic C₆₀ end‐capped polymers under microwave irradiation

Synthesis of telechelic C₆₀ end‐capped polymers under microwave irradiation