Laboratorio virtual LAVIDITA

Lavidita proporciona al alumno de un entorno que le permitirá potenciar tanto su capacidad científica, mejorar su productividad académica, mediante una herramienta docente didáctica, de fácil uso que le resulte práctica y eficaz para introducirse en el campo de La hidráulica, hidrodinámica, morfodinámica fluvial y otros fenómenos de flujos asociados al medio ambiente. Este proyecto virtual a su vez vence las barreras prácticas en la docencia experimental y permite al alumno el acceso a experimentos no habituales en laboratorios convencionales. La metodología de aplicación es un Cd interactivo muy simple en el cual se desarrollan básicamente tres temas: transporte de sedimentos, mecánica de fluidos y mezcla mediante ejemplos visuales y gráficos interactivos del desarrollo de experimentos controlados, en los que le permite resolver problemas, hacer demostraciones, mediciones y otras actividades prácticas y teóricas

Tsunamis generated by fast granular landslides: 3D experiments and empirical predictors

Landslides falling into water bodies can generate impulsive waves, which are a type of tsunamis. The propagating wave may be highly destructive for hydraulic structures, civil infrastructure and people living along the shorelines. A facility to study this phenomenon was set up in the laboratory of the Technical University of Catalonia. The set-up consists of a new device releasing granular material at high velocity into a wave basin. A system employing laser sheets, high-speed and high-definition cameras was designed to accurately measure the high velocity and geometry of the sliding mass as well as the produced water displacement in time and space. The analysis of experimental data helped to develop empirical relationships linking the landslide parameters with the produced wave amplitude, propagation features and energy, which are useful tools for the hazard assessment. The empirical relationships were successfully tested in the case of the 2007 event that occurred in Chehalis Lake (Canada).Peer ReviewedPostprint (author's final draft

Coherent structures in oscillatory flows within the laminar-to-turbulent transition regime for smooth and rough walls

This is an Accepted Manuscript of an article published by Taylor & Francis Group in [Journal of hydraulic research] on [2016], available online at: http://www.tandfonline.com/10.1080/00221686.2016.1174960We investigate coherent structures present in oscillatory boundary layers over smooth and rough beds for Reynolds numbers between 103 and 104, in the transition to turbulence regime. A two-camera 2D- particle image velocimetry (PIV) system was used to visualize coherent structures in an oscillatory-flow tunnel. The obtained results show that smooth-bed flow is populated by vortex-tube structures that are formed due to the Kelvin–Helmholtz instability. Three types of coherent structures are observed in the rough-wall experiments: vortices randomly distributed in space; turbulent bursts – spatial structures without a clear shape compared to vortices but with a longer life than the former; and shear layers of vortices originating due to flow separation from some of the grains on the bed. The reported study contributes to the description of coherent structures in oscillatory flows that are captured with the PIV technique, particularly a new structure in flows over rough beds in the transition to turbulence regime.Peer ReviewedPostprint (author's final draft

Experimental and Theoretical Modelling of 3D Gravity Currents

Postprint (published version

Virtual patient design : exploring what works and why : a grounded theory study

Objectives: Virtual patients (VPs) are online representations of clinical cases used in medical education. Widely adopted, they are well placed to teach clinical reasoning skills. International technology standards mean VPs can be created, shared and repurposed between institutions. A systematic review has highlighted the lack of evidence to support which of the numerous VP designs may be effective, and why. We set out to research the influence of VP design on medical undergraduates. Methods: This is a grounded theory study into the influence of VP design on undergraduate medical students. Following a review of the literature and publicly available VP cases, we identified important design properties. We integrated them into two substantial VPs produced for this research. Using purposeful iterative sampling, 46 medical undergraduates were recruited to participate in six focus groups. Participants completed both VPs, an evaluation and a 1-hour focus group discussion. These were digitally recorded, transcribed and analysed using grounded theory, supported by computer-assisted analysis. Following open, axial and selective coding, we produced a theoretical model describing how students learn from VPs. Results: We identified a central core phenomenon designated ‘learning from the VP’. This had four categories: VP Construction; External Preconditions; Student–VP Interaction, and Consequences. From these, we constructed a three-layer model describing the interactions of students with VPs. The inner layer consists of the student's cognitive and behavioural preconditions prior to sitting a case. The middle layer considers the VP as an ‘encoded object’, an e-learning artefact and as a ‘constructed activity’, with associated pedagogic and organisational elements. The outer layer describes cognitive and behavioural change. Conclusions: This is the first grounded theory study to explore VP design. This original research has produced a model which enhances understanding of how and why the delivery and design of VPs influence learning. The model may be of practical use to authors, institutions and researchers

Erosión local en pilas de puente: los procesos y su mitigación. Aplicación al pabellón puente de la Expo 2008 de Zaragoza

Se exponen los avances en el estudio de la erosión local en pilas de puente gracias a la experimentación en modelos a escala reducida en laboratorio. Se describe la evolución temporal, las características de la erosión local en pilas de base cuadrada y circular, la influencia de las presiones no hidrostáticas, así como también la protección que ha de utilizarse para mitigar la erosión. Desde el punto de vista de la ingeniería el uso de modelos reducidos es imprescindible debido a la complejidad de los fenómenos que intervienen. Se presenta la aplicación a la evaluación del riesgo de erosión fluvial en una pila compleja de gran anchura, construida en el cauce del río Ebro en Zaragoza. Se describe el problema de erosión local, las características del modelo físico ensayado y los mantos de escollera que consiguen detener la erosión, así como la ejecución y auscultación de esta protección.Peer Reviewe

Group delay in Bragg grating with linear chirp

An analytic solution for Bragg grating with linear chirp in the form of confluent hypergeometric functions is analyzed in the asymptotic limit of long grating. Simple formulas for reflection coefficient and group delay are derived. The simplification makes it possible to analyze irregularities of the curves and suggest the ways of their suppression. It is shown that the increase in chirp at fixed other parameters decreases the oscillations in the group delay, but gains the oscillations in the reflection spectrum. The conclusions are in agreement with numerical calculations.Comment: 16 pages, 8 figures, submitted to Opt. Com

Where has all the youth crime gone? youth justice in an age of austerity

Youth justice under the Coalition government in England and Wales has been characterised by considerable gains — falling youth crime, increased diversion and substantial reductions in child imprisonment — that would generally be associated with a progressive agenda. Focusing on youth justice policy in England and Wales, this article suggests that the tensions implicit in a government of the new right delivering outcomes that demonstrate an increased tolerance to children who offend can be explained by the logic of austerity. That same logic brings with it other policy measures that are potentially less compatible with children's well-being

Versatile image-based measurements of granular flows and water wave propagation in experiments of tsunamis generated by landslides

Landslides falling into water bodies can generate destructive waves, which can be classified as tsunamis. An experimental facility to study this phenomenon has been set up. It consists of a landslidegenerator releasing gravel at high-speed into a wave basin. A non-intrusive system has been designed ad-hocto be able to measure the high velocity and the geometry of the landslide as well as the generated waves characteristics. The measurement system employs the treatment of images captured by a high-speed camera which records the launched granular material illuminated by a laser sheet. A grid of laser sheets marks thebasin water surface. The water has been filled by a small amount of kaolin to properly reflect the laser lightat water surface. Thus, by filming with high definition cameras the perturbed water surface and successively processing the resulting images, it has been possible to measure the generated waves. The measurement framework employs a versatile camera calibration technique which allows accurate measurements in presence of: (1) high lens distortions; (2) pronounced non-parallelism condition between camera sensor and plane of measurement coincident with the laser sheet. The maximum resolution of the measurement tool is0.01 mm, while the maximum uncertainty due to systematic error has been estimated to be 15% for theworst-case scenario. This work improves the suitability of image-based measuring systems in granular flows and free surface hydraulics experimentsThis work was funded by GITS and the 3 years’ national project DEBRIS FLOW (CGL 2009-13039) ofthe Spanish Ministry of Education. Francesco Bregoli has been supported by the 4-years grant FPU2009-3766 of the SpanishMinistry of Education. Authors want to thank Dr. Cecilia Caldini (IDOM Consulting, Barcelona) for the 3D reconstruction ofthe laboratory setup.Peer ReviewedPostprint (published version