Examinando por Materia "Transformada de Wavelet"
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Publicación Análisis de técnicas Wavelet para el desarrollo de compresores de audio(Universidad EAFIT, 2017) Medina Sánchez, Laura Victoria; Villegas Gutiérrez, Jairo AlbertoPublicación Analysis of Atmosphere-Plant-Soil Interactions(Universidad EAFIT, 2025) Revelo Aristizábal, Mauricio Felipe; Ruiz Restrepo, Daniel Felipe; Universidad EAFIT, InnovaciónUnderstanding the interactions between the atmosphere, vegetation, and soil is essential for addressing issues related to slope stability, water transfer, and thermal variability in geological media, particularly under changing climatic conditions. These interactions govern coupled processes in soils and rocks and have implications for geotechnical engineering, land management, and environmental sustainability. Vegetation plays a central role in regulating the soil's hydromechanical balance by promoting infiltration, reducing runoff, and providing reinforcement through root systems. This thesis investigates the Soil–Atmosphere continuum, with a specific focus on the role of vegetation. The document is structured into three chapters and three appendices, each contributing to a detailed analysis of the topic. Chapter 1 addresses the Soil–Atmosphere system from a thermo-hydro-mechanical perspective and develops two complementary approaches. The first examines the role of vegetation, emphasizing root geometry and reviewing current formulations reported in the literature. In addition, the importance of in situ geotechnical monitoring for studying the Atmosphere–Plant–Soil interface is discussed through case studies. Chapter 2 presents a methodology based on digital image processing to visualize and quantify root system architecture. This method yields geometric parameters that support interpretation in Plant–Soil applications and the evaluation of nature-based solutions. The chapter highlights the role of visual analysis as a bridge between theoretical concepts and observational data. Chapter 3 analyzes time series obtained from multisensor networks applied to Soil–Atmosphere interactions at three monitoring points with distinct climatic and geotechnical conditions. Vegetation variables are not included in these case studies. Spectral techniques such as the Wavelet transform and the Hilbert–Huang transform were applied to identify dominant periodicities and evaluate potential relationships among variables such as precipitation, soil moisture, temperature, and displacement. The analysis includes coherence estimation and Spearman correlation between intrinsic mode functions (IMFs) to examine temporal coupling among environmental variables at multiple scales. Appendix 1 presents the theoretical foundations of thermo-hydro-mechanical processes in porous media. Appendix 2 contains soil characterization data from a monitored site where vegetation was grown under natural conditions. Appendix 3 includes complementary visualizations of the time-series analysis, featuring the complete spectral decompositions.Publicación Correlación serial con Wavelets(Universidad EAFIT, 2007) Villa Valencia, Alberto Antonio; Martínez Plazas, Javier; Villegas Gutiérrez, Jairo Alberto; Zuluaga Díaz, Francisco IvánPublicación Estimación de un modelo del precio de la energía eléctrica en Colombia con detección de puntos de volatilidad, utilizando la transformada Wavelet y series de tiempo(Universidad EAFIT, 2018) Arbeláez Arcila, Jesús Alonso; Trespalacios Carrasquilla, AlfredoIn this document we propose a technique to estimate a model of the price of electric power in Colombia, using the filtering properties of the Discrete Wavelet Transform (DWT) and the traditional time series modeling techniques ARIMA, GARCH; in addition, the detection of points of change in the variance of the price series through the detection method of multiple changes in a sequence of dependent variables; the series of spot prices is decomposed in a series of approximation and several details, then each sub-series separately is modeled with the technique that best fits the data -- The final forecast is the sum of the reconstructed forecasts obtained from each sub-series -- The most important conclusion of the proposed model is to allow greater precision in the forecast and, in turn, detect points of volatility change due to exogenous variables in the series of spot prices of the Colombian electricity marketPublicación Non parametric and robust statistical test based on wavelets for time series classification(Universidad EAFIT, 2018) Sánchez González, Alejandra; Laniado Rodas, Henry; Ríos Querubín, MateoIn this article a statistical procedure for identifying if a time series set follows the same model is developed -- With the aim of supporting characterization and pattern recognition for temporal series, and inspired by the methodology of Maharaj E. A.[1], we take advantage of the wavelet coefficients properties to characterize a signal and our procedure is made by means of a randomization test on those coefficient -- Our main contribution in this work is to introduce modified versions of test statistic in test for pattern recognition of time series which in general, have a great performance in terms of size and power, both being desirable features in a statistic test -- It is worth pointing out that we introduce robust statistical tests whose performance are better in presence of atypical values than some techniques already studied in the literature -- The methodology developed here allow us to design a new method to classify time series and atypical values identification -- We implement our new methods in real and simulated casesPublicación Solución numérica de la ecuación KDV utilizando representación de operadores diferenciales en base wavelet(Universidad EAFIT, 2016) Castro Rodríguez, Denis Alberto; Aramburo Palacios, Darwin; Villegas Gutiérrez, Jairo Alberto; Castaño Bedoya, Jorge Iván