Persona: Rubio Álvarez, Miguel Ángel
Cargando...
Dirección de correo electrónico
ORCID
0000-0002-4210-0443
Fecha de nacimiento
Proyectos de investigación
Unidades organizativas
Puesto de trabajo
Apellidos
Rubio Álvarez
Nombre de pila
Miguel Ángel
Nombre
6 resultados
Resultados de la búsqueda
Mostrando 1 - 6 de 6
Publicación Red Interactiva de Inteligencia Colectiva para el servicio Exterior venezolano (RINCEX)(2007-06-18) Alves Pérez, Elisabeth; Rubio Álvarez, Miguel ÁngelPublicación Flow field based data processing for the oscillating conical bob interfacial shear rheometer(American Institute of Physics, 2018-01-01) Pastor Ruiz, Juan Manuel; Tajuelo Rodríguez, Javier; Rubio Álvarez, Miguel ÁngelA rotational rheometer can be used as an interfacial shear rheometer (ISR) by means of proper accessories that allow one to shear fluid-fluid interfaces in a controlled manner. One of the most used accessories, even commercially available, is based on a biconical bob geometry. However, recovering the correct values of the rheological variables is far from trivial. A strategy that has proved to be successful in other ISRs is to properly account for the interface and subphase drags by numerically finding the corresponding flow fields and, then, use an iterative scheme to recover the proper values of the complex Boussinesq number and, consequently, the dynamic surface moduli. Here, we propose to use such a scheme for the biconical bob oscillatory rheometer. We compare our solution with different well known previous approximations, and discuss under which conditions those approximations may lead to errors in the data processing. We have tested the performance of our design and numerical framework on several interfacial systems, comparing the results to those obtained through a magnetic needle rheometer (ISR). We demonstrate that, even for relatively low values of the Boussinesq number, the numerical flow field solution here proposed allows one to precisely reproduce the results obtained by the ISR, while those approximations based on a linear velocity decay at the interface may introduce spurious effects on the calculation of the dynamic surface moduli.Publicación Linear shear rheology of aging β-casein films adsorbing at the air/water interface(Elsevier, 2018-02-01) Martínez Pedrero, F.; Sánchez Puga, Pablo; Chulia Jordan, R.; González Rubio, Ramón; Tajuelo Rodríguez, Javier; Ortega Coloma, Francisco Javier; Rubio Álvarez, Miguel ÁngelIn this work, the viscoelasticity of fragile β-casein films has been followed using different macro- and microrheological techniques. The modulus of the complex surface viscosity varies with time, allowing for the monitoring of the protein adsorption and annealing. β-casein adsorption creates a soft glassy gel at the interface that experiences an aging process. Macrorheological experiments with multiple probe sizes in addition to microrheological experiments demonstrated the consistency of the surface rheological properties over a broad range of viscosities. Surface pressure measurements were performed to complement the characterization of the processes.Publicación BiconeDrag—A data processing application for the oscillating conical bob interfacial shear rheometer(Elsevier, 2019-06) Sánchez Puga, Pablo; Pastor Ruiz, Juan Manuel; Tajuelo Rodríguez, Javier; Rubio Álvarez, Miguel ÁngelBiconeDrag is a software package that allows one to perform a flow field based data processing of dynamic interfacial rheology data pertaining to surfactant laden air–fluid interfaces obtained by means of a rotational bicone shear rheometer. MATLAB and Python versions of the program are provided. The bicone fixture is widely used to transform a conventional bulk rotational rheometer into an interfacial shear rheometer. Typically, such systems are made of a bicone bob, which is mounted on the rheometer rotor, and a cylindrical cup. Usually, the experiment consists of measuring the response of the interface under an oscillatory stress. The program takes the values of the torque/angular displacement amplitude ratio and phase difference to compute the interfacial dynamic moduli (or complex viscosity) by consistently taking into account the hydrodynamic flow both at the interface and the subphase. This is done by numerically solving the Navier–Stokes equations for the subphase velocity field together with the Boussinesq–Scriven boundary condition at the interface, and no slip boundary conditions elsewhere. Furthermore, the program implements a new iterative scheme devised by solving for the complex Boussinesq number in the rotor’s torque balance equation.Publicación Shear rheology of fluid interfaces: Closing the gap between macro- and micro-rheology(Elsevier, 2018-09) Guzmán Solís, Eduardo; Pastor Ruiz, Juan Manuel; González Rubio, Ramón; Tajuelo Rodríguez, Javier; Rubio Álvarez, Miguel Ángel; Ortega Coloma, Francisco JavierFor many years the determination of the shear viscosity of interfacial layers has been source of strong controversy. This is mainly because different techniques provided different values of such parameter, which leads in many cases to a puzzling interpretation of the experimental results. One possible explanation of this is the non-correct analysis of the hydrodynamic conditions of the measurement and, in particular, the assumption of some approximations that may not be necessarily valid in all cases. The introduction of hydrodynamic consideration in the study of interfacial shear rheology has helped to clarify some of the existing discrepancies between measurements performed using different devices, thus allowing one to establish clearly the viscosity range in which different techniques can operate with enough sensitivity for determining the interfacial shear viscosity. This review puts in perspective the most recent developments on the studies of the interfacial shear rheology of fluid/fluid interfaces, analyzing the strength and weakness of the different approaches.Publicación Prácticas de simulación en la asignatura "Teoría de circuitos y electrónica"(Universidad Nacional de Educación a Distancia (España). Instituto Universitario de Educación a Distancia (IUED), 2019) Montoya Lirola, María del Mar; Rubio Álvarez, Miguel ÁngelSe presenta una actividad desarrollada por el equipo docente de la asignatura «Teoría de circuitos y electrónica» con el objetivo de fomentar una mayor participación del estudiante en su proceso de aprendizaje y de desarrollar nuevos métodos de evaluación de los resultados de aprendizaje. La actividad consiste en ofertar un conjunto de prácticas de simulación para su realización de manera voluntaria por parte de los estudiantes. La puesta en marcha de la actividad ha comprendido la elección del software, la realización de un tutorial y de unas tutorías en línea y la elaboración de los guiones de prácticas. La evaluación de los resultados de aprendizaje se lleva a cabo a través de las memorias de prácticas que elaboran los estudiantes y su contribución a la calificación final es de tipo sumativo.