Ana Vidaurre

Measuring coupled oscillations using an automated video analysis technique based on image recognition

The applications of the digital video image to the investigation of physical phenomena have increased enormously in recent years. The advances in computer technology and image recognition techniques allow the analysis of more complex problems. In this work, we study the movement of a damped coupled oscillation system. The motion is considered as a linear combination of two normal modes, i.e. the symmetric and antisymmetric modes. The image of the experiment is recorded with a video camera and analysed by means of software developed in our laboratory. The results show a very good agreement with the theory.

Contribution of digital simulation in visualizing physics processes

In our experience of teaching physics for engineering at university level we have learned that the mathematical relationships between the parameters that control a process are important, but not sufficient, to understand a process. Such knowledge will only be consolidated if the new concept is incorporated by student in his field of study. Simulation programs, especially through visualization, can help to attain this target. We have developed three programs using Visual Basic. One of them is devoted to fitting experimental data and is complementary to experimental work; the others focus on dynamics, translation, and rotational movement, helping to understand the Newtons laws.

Digital simulation of wave motion

Information and communication technologies have been shown to be very effective in the transmission of scientific knowledge. Nowadays, the development of software and hardware makes it possible to simulate processes as close to reality as we want. However, when we are trying to explain some complex physical processes, it is better to simplify the problem by means of simplified pictures of the total process. In the present work, we analyze the design of a simulation program of wave motion developed in our laboratory. The aim of the program is to help students to understand the basic concepts of the wave motion. For this reason, we have paid special attention to interactivity and graphic aspects.

Hydrophilic sponges based on poly(hydroxyethyl acrylate)

Abstract Hydrophilic sponges were prepared by co-polymerisation of hydroxyethyl acrylate and ethylene-glycol dimethacrylate in solution. The porous structure of the sponge is due to the segregation of the solvent from the polymer network during the polymerisation process as the result of a large excess of solvent. The influence of the solvent and the monomer/solvent ratio on the formation of the porous structure is studied. The morphology of the samples was examined in a scanning electron microscope equipped with a cryounit using the low-temperature freeze drying technique cryogenic scanning electron microscope (cryoSEM). Equilibrium water sorption isotherms of the sponge and the parameters that fit the Guggengeim–Anderson–De Boer equation are presented. The water uptake in immersion in liquid water can be used to estimate the volume fraction of pores in the sponge.

Testing Theoretical Models of Magnetic Damping Using an Air Track.

Magnetic braking is a long-established application of Lenzs law. A rigorous analysis of the laws governing this problem involves solving Maxwells equations in a time-dependent situation. Approximate models have been developed to describe different experimental results related to this phenomenon. In this paper we present a new method for the analysis of magnetic braking using a magnet fixed to the glider of an air track. The forces acting on the glider, a result of the eddy currents, can be easily observed and measured. As a consequence of the air track inclination, the glider accelerates at the beginning, although it asymptotically tends towards a uniform rectilinear movement characterized by a terminal speed. This speed depends on the interaction between the magnetic field and the conductivity properties of the air track. Compared with previous related approaches, in our experimental setup the magnet fixed to the glider produces a magnetic braking force which acts continuously, rather than over a short period of time. The experimental results satisfactorily concur with the theoretical models adapted to this configuration.

Endoworm: A new semi-autonomous enteroscopy device

Using enteroscopes with therapeutic capacity to explore the small intestine entails certain limitations, including long exploration times, patient discomfort, the need for sedation, a high percentage of incomplete explorations and a long learning curve. This article describes the advances and setbacks encountered in designing the new Endoworm enteroscopy system, a semi-autonomous device consisting of a control unit and three cavities that inflate and deflate in such a way that the bowel retracts over the endoscope. The system can be adapted to any commercial enteroscope. Endoworm was tested in different intestine models: a polymethyl methacrylate rigid tube, an in vitro polyester urethane model, an ex vivo pig model and an in vivo animal model. The general behavior of the prototype was evaluated by experienced medical personnel. The mean distance covered through the lumen was measured in each cycle. The system was found to have excellent performance in the rigid tube and in the in vitro model. The ex vivo tests showed that the behavior depended largely on the mechanical properties of the lumen, while the in vivo experiments suggest that the device will require further modifications to improve its performance.

Evaluación entre compañeros de la comunicación oral efectiva

La evaluacion entre companeros es una forma de aprendizaje colaborativo en el que los estudiantes valoran el producto de aprendizaje de otros estudiantes. En nuestro caso, efectuan dos tipos de evaluacion relacionados con la comunicacion efectiva: en equipo evaluan cuantitativamente documentos con la resolucion de problemas de otros equipos, y, posteriormente, evaluan cualitativamente las presentaciones orales de los ejercicios. Se les han dado pautas sobre como llevar a cabo la evaluacion. El resultado ha sido comparado con la evaluacion hecha por los profesores. En la evaluacion cualitativa de las presentacions no se ha encontrado diferencias significativas entre la realizada por los alumnos en equipo y la de los profesores. Ademas, la argumentacion que hacen a las valoraciones son rigurosas y muestran su aprendizaje a traves del trabajo hecho por los companeros.

Using 3D virtual environments to visualize wave interference phenomena

Information and Communication Technologies have demonstrated to be extremely effective in the transmission of scientific knowledge. Nowadays, the development of software and hardware makes it possible to simulate physical processes as close to reality as required. Furthermore, complex physical processes benefit from graphical simplicity in order to emphasize the main points for a complete understanding. In this work we focus our attention on the interference of coherent scalar waves in homogeneous media. Digital simulations have been designed in order to help the students to understand this phenomenon. Examples of interference of plane waves and cylindrical waves are visualized in sapce-time scales as the main advantage over traditional teaching resources.