The growth of titanium dioxide nanotubes (TiO2) via anodization process depends on the controlling parameters such as applied potential, anodization time, and electrolyte composition. In the present work, the Taguchi method was applied to evaluate statistically the influence of the anodization parameters on the morphology of anodized TiO2 films. Mixture of ethylene-glycol and glycerol was used as an electrolyte and the settings of the experimental design were parameterized on the basis of four important anodization factors consisting of chemical pretreatment, amount of fluoride, water content and applied potential. Samples were characterized by XRD and FEG-SEM. Based on 4 variables at 3 different settings, full factorial plan requires 34 = 81 tests. In this work the experiment was designed on the basis of an L9 (34) orthogonal array (4 variables, 3 levels, 9 tests). The optimum conditions were found on the basis of smaller-is-better and larger-is-better analyses. The signal-to-noise ratio was employed to find optimal process parameters levels and to analyze the influence of these parameters on the tubular length, internal and external diameters and formation of nanograss on the film surface. Hence, it is clearly shown that the performance of TiO2 nanotubes can be evaluated by the Taguchi method.

Este artigo apresenta um método adaptado do estudo de repetitividade e reprodutividade (R& R) para analisar a capacidade e o desempenho de sistemas de medição, no contexto da análise de dados funcionais. Dados funcionais ocorrem quando a variável de resposta é caracterizada por uma coleção de dados que formam um perfil ou uma curva, e não por uma observação individual. O método proposto é uma alternativa ao uso de métodos tradicionais de análise, que são ineficientes para dados funcionais. O método apresenta uma adaptação da análise de variância de dois fatores. Foi usada a distância de Hausdorff como medida de proximidade entre as curvas. O método proposto foi aplicado a um estudo simulado de R& R. O estudo foi estruturado para analisar cenários em que o sistema de medição foi aprovado e reprovado. Os resultados foram comparados com os obtidos através da aplicação da ANOVA ponto a ponto nas curvas. O método proposto foi denominado de ANOVA das distâncias.

This paper presents a method to analyze the performance of measurement systems in a functional data analysis context, based on repeatability and reproducibility (R& R) studies. Functional data are a collection of data points organized as a profile or curve. The method is an alternative to traditional methods that may lead to wrong conclusions when applied to functional data. In the proposed method, hypothesis tests and two-way ANOVA were adapted to be used in measurement system analysis. The method is grounded on the use of the Hausdorff distance to measure the proximity between curves. The method proposed was applied in a simulated repeatability and reproducibility study. The study was structured such that scenarios in which the measurement system was approved and rejected were tested. Results were compared with those obtained applying traditional ANOVA point wise on the curves. The method proposed was named ANOVA of the distances.