Problemática, metodología y teoría: el recorrido de un grupo de investigación en enseñanza de las ciencias

This paper discusses some results obtained from research on the teaching of mechanics to initial university courses in Brazil, together with the epistemological problems arising

Cinemática : de los números a las representaciones algebraicas

Se presenta el análisis de un cuestionario que enfoca el problema del uso de la matemática en cinemática elemental, tomado a alumnos universitarios de primer año. El marco teórico que orienta la investigación es el Modelo de Redescripción Representacional de Karmiloff-Smith. Los datos obtenidos muestran los diferentes niveles de explicitación de las representaciones y la variedad y singularidad de los recursos que utilizan los alumnos para resolver las cuestiones planteadas. La presentación de la representación algebraica, permite observar cómo los alumnos van integrando esta herramienta, la combinan con sus formas de resolución y la descartan cuando no les proporciona una forma de llegar al resultado. Puede observarse una relación directa entre poder explicitar con más detalle las cuentas que hicieron para llegar a un resultado y cuán lejos llegan en la resolución

Predictive Missile Guidance with Online Trajectory Learning

This study presents a predictive guidance scheme for tactical missiles. The modern day targets, with improved manoeuverability, have revealed insufficient performance of the conventional guidance laws. The underlying cause of this poor performance is the reactive nature of the conventional guidance laws such as proportional navigation (PN) and pure pursuit (PP). Predictive guidance offers an alternative approach to the classical methods by taking proactive actions by estimating target’s future trajectory. However, most of the existing predictive guidance approaches assume that the interceptor have a model of the target dynamics. A guidance strategy is developed in this study, that can learn the target dynamics iteratively and adapt the interceptor actions accordingly. A recursive least squares (RLS) estimation algorithm is employed for learning and estimating the possible future target positions, and a fixed horizon nonlinear program is employed for selecting the optimal interception action. Monte-Carlo simulations show that the guidance algorithm introduced in this work demonstrates a significantly improved performance compared to the alternatives in terms of interception time and miss distance

Abstractions, accounts and grid usability

The vision of the Grid is one of seamless, virtual and constantly changing resources where users need not concern themselves about details, such as exactly where an application is running or where their data is being stored. However, seamless and virtual often imply a lack of control that users may be wary of, or even opposed to. Drawing upon our studies of HCI and of collaborative work, this paper examines whether the Grid development community should be taking this vision literally and argues for the need for accountability of systems ‘in interaction’. We give examples of an alternative approach that seeks to provide ways in which administrators, technical support and user communities can make sense of the behaviour of the complex socio-technical ensembles that are the reality of Grids

Mobilising communities to address alcohol harm : an Alcohol Health Champion approach

In this article, Cathy Ure et al. look at engaging communities in order to reduce alcohol harms. By training Alcohol Health Champions, individuals can support vulnerable friends and family, and work within their communities to influence policy and promote change

Final Year Preservice Teachers\u27 Views of Professional Experience in Partnership Schools

This study investigated the perspectives of preservice teachers’ (PSTs) on their final year placements in Initial Teacher Education (ITE) programs offered at Deakin University, Victoria, Australia. It compared the views of PSTs in two placement models; the Alliance school (partnership)and non-Alliance school (or conventional) models. The Alliance model draws on Activity Theory (Engeström, 2015) to strengthen the links between theory and practice in ITE, providing additional support during school placements through an ‘in situ’ boundary crosser. These boundary crossers use an Assessment Circle process that supports professional conversations about teaching and learning. A mixed method approach has been used to compare the reported experiences of final year PSTs who completed placements in an Alliance partnership schools or a non-Alliance schools. Findings indicate significant differences in the experiences of the two cohorts of PSTs in relation to perceived levels of support and their understanding of the Australian Professional Standards for Teachers (AITSL, 2011)

Multiple-Criteria Decision Analysis and characterisation of phase change materials for waste heat recovery at high temperature for sustainable energy-intensive industry

A latent heat storage system based on Phase Change Materials (PCMs) is proposed to increase the energy and environmental efficiency by recovering and storing waste heat from combustion gases or other surplus sources at in the energy-intensive industries (EII), currently unused. The final configuration design is specifically adapted to the plant operational requirements, by means of a methodology combining the search of the best conceptual design and a proper selection of core PCMs. To that end, a selection of suitable PCM is carried out by using characterisation techniques and thermal stability testing. Furthermore, relevant key factors are weighted by an in-house Multiple-Criteria Decision Analysis (MCDA) to define the most promising design options to be implemented in two plants belonging to the EII sector. For the ceramic sector, the design resulted in a shell-and-tube system with 1188 kg of a PCM melting at 885 °C and encapsulated in double concentric tubes, involving a storage capacity of 227 MJ. Similarly, 1606 kg of PCM, whose phase-change temperature is 509 °C, is selected for the steel sector providing a PCM-TES system capable to store 420 MJ