Examinando por Materia "ONDAS ELECTROMAGNÉTICAS"
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Ítem Caracterización de Materiales Ferroeléctricos en Frecuencias de Microondas(Universidad EAFIT, 2019) Gallo Castrillón, Wilson Henry; Marulanda Bernal, José Ignacio;71696211This dissertation aims at the implementation of a technique of dielectric characterization of ferroelectric ceramic materials at microwave frequencies, to measure dielectric constant and loss tangent associated with the propagation of electromagnetic waves (Tan δ) with frequencies up to 8.5 GHz. For the characterization of the ferroelectric materials, the coatings were synthesized by spin-coating technique and then a gradual heat treatment was avoid cracking during the drying process. For this, sputtering techniques (RF magnetron sputtering) were explored using Barium Titanate targets (BaTiO3) and Strontium Titanate (SrTiO3) at 99.99% (manufacturer); Chemical solution (Sol-Gel) techniques of ferroelectric materials deposited on a metallized alumina substrates. The films obtained were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS). The technique of dielectric characterization implemented as part of this work consists of depositing the material to be analyzed on a coplanar waveguide resonator circuit (CPW). The dielectric constant and its loss tangent can be determined from the frequency response of the resonator coated with the sample material. The obtained results confirm the synthesis of Barium Titanate with cubic structure, with homogeneous distribution on surfaces and few surface defects on metallized alumina substrates. The dielectric characterization shows a relative dielectric constant 𝜀𝑟≈20, a very promising result. However, the tangent of losses despite not reporting optimal levels (Tan δ ≈0.001), these adjust to results reported in studies of similar characteristics.Ítem ¿Cómo funcionan las redes inalámbricas?(2012) Abad Restrepo, Ana Cristina; Marulanda Bernal, José Ignacio; Vidal Ramírez, Alejandra; Muriel Gil, Luisa Fernanda; Uribe Dorado, Jose Ignacio; Rincon, Diana Marcela .; Ana Cristiba Abad Restreppo (abad@eafit.edu.co); José Marulanda (jmarulan@eafit.edu.co)Ítem Diseño de una cocina solar para actividades de camping o afines(Universidad EAFIT, 2009) Monsalvo Londoño, Luis Carlos; Zamora Suárez, Óscar Hernando; París Londoño, Luis SantiagoPor medio de este trabajo se pretende dar a conocer la ventaja funcional que tienen las cocinas solares durante el desarrollo de algunas actividades al aire libre como es el picnic o el camping -- Adicionalmente se busca concebir un producto diseñado, inicialmente en consideración a las demandas asociadas a los grupos de scouts, desde su estilo de vida, hábitos comunes de consumo y el contexto en el cual se desenvuelven -- Para lograr obtener un producto que pueda vincularse a este usuario en particular se emplean diversas estructuras metodológicas de investigación y síntesis, por medio de las cuales se retoman todos aquellos aspectos relevantes en cualquier proceso de diseño de producto como son; la definición e identificación detallada del tipo de usuario, factores ergonómicos asociados a éste, la estructuración funcional asociada a una propuesta formal coherente, la identificación de procesos adecuados de producción, el potencial económico en comparación a la competencia del mercado y el compromiso ambiental del producto vinculado a su ciclo de vida -- Una vez se desarrolló todo este proceso de investigación, formalización y conceptualización, se evaluó la alternativa de solución propuesta, a partir de la materialización de un modelo funcional a escala real que permitió evaluar el desempeño del productoÍtem Diseño, construcción y prueba de un prototipo calentador solar de agua con tubos de calor(Universidad EAFIT, 2007) Mira Hernández, Carolina; París Londoño, Luis SantiagoÍtem ¿Es real todo lo que percibimos con nuestros ojos?(2012) Velásquez Prieto, Daniel Ignacio; Abad Restrepo, Ana Cristina; Daniel Velásquez (dvelas@eafit.edu.co); Ana Cristina Abad (abad@eafit.edu.co)Ítem Estudio de sistemas de detección e inhibición para emisores celulares presentes en redes comerciales(Universidad EAFIT, 2014) Carmona Valencia, Augusto; Marulanda Bernal, José IgnacioÍtem Métricas para evaluación de la calidad del sonido(Universidad EAFIT, 2012) Herrera Rendón, Juan David; Castañeda Heredia, Leonel FranciscoÍtem Simulation and parameterization by the finite element method of a C Shape Delectromagnet for application in the characterization of magnetic properties of materials(World Academy of Science, Engineering and Technology, 2012-11-22) Velásquez Torres, Álvaro Andrés; Baena Rodríguez, Juliana; Universidad EAFIT. Departamento de Ciencias Básicas; avelas26@eafit.edu.co; Electromagnetismo Aplicado (Gema)This article presents the simulation, parameterization and optimization of an electromagnet with the C–shaped configuration, intended for the study of magnetic properties of materials -- The electromagnet studied consists of a C-shaped yoke, which provides self–shielding for minimizing losses of magnetic flux density, two poles of high magnetic permeability and power coils wound on the poles -- The main physical variable studied was the static magnetic flux density in a column within the gap between the poles, with 4cm2 of square cross section and a length of 5cm, seeking a suitable set of parameters that allow us to achieve a uniform magnetic flux density of 1x104 Gaussor values above this in the column, when the system operates at room temperature and with a current consumption not exceeding 5A -- By means of a magnetostatic analysis by the finite element method, the magnetic flux density and the distribution of the magnetic field lines were visualized and quantified -- From the results obtained by simulating an initial configuration of electromagnet, a structural optimization of the geometry of the adjustable caps for the ends of the poles was performed -- The magnetic permeability effect of the soft magnetic materials used in the poles system, such as low–carbon steel (0.08% C), Permalloy (45% Ni, 54.7% Fe) and Mumetal (21.2% Fe, 78.5% Ni), was also evaluated -- The intensity and uniformity of the magnetic field in the gap showed a high dependence with the factors described above -- The magnetic field achieved in the column was uniform and its magnitude ranged between 1.5x104 Gauss and 1.9x104 Gauss according to the material of the pole used, with the possibility of increasing the magnetic field by choosing a suitable geometry of the cap, introducing a cooling system for the coils and adjusting the spacing between the poles -- This makes the device a versatile and scalable tool to generate the magnetic field necessary to perform magnetic characterization of materials by techniques such as vibrating sample magnetometry (VSM), Hall-effect, Kerr-effect magnetometry, among others -- Additionally, a CAD design of the modules of the electromagnet is presented in order to facilitate the construction and scaling of the physical device