Evaluación de servicios educativos: el rendimiento en los centros públicos y privados medido en PISA-2003

Este artículo tiene como objetivo principal conocer el efecto del tipo de centro educativo y, en concreto, su titularidad (pública o privada) sobre los resultados de los usuarios del sistema educativo español. El análisis empírico se basa en la aplicación de técnicas de regresión multinivel a los datos procedentes de la evaluación efectuada en el programa PISA-2003, de la OCDE. Los resultados del análisis dan respaldo a la hipótesis de trabajo, en la que se afirma que las diferencias de puntuaciones que se observan a favor de los centros privados no vienen explicadas por la titularidad del centro, sino por otras variables referidas a los usuarios (individuales y familiares), a sus compañeros y al propio centro.financiación de la educación, evaluación de servicios públicos, rendimiento educativo, análisis multinivel, programa PISA

Barriers to non-formal professional training in Spain in periods of economic growth and crisis. An analysis with special attention to the effect of the previous human capital of workers

We analyze the determining factors of access to non-formal professional training in Spain and their evolution in recent years. Specifically, a comparison is made between a moment during a period of economic growth (2007) and the current crisis period (2012). The data used is from the Economically Active Population Survey. The sample is divided according to gender and interaction variables are included to analyze the differential effects of human capital on the probability of receiving training in the two periods considered. The hypothesis is that there are significant barriers that make access to non-formal professional training difficult (we focus on previous human capital available) and that these barriers have not ceased to operate during the economic crisis

Teacher quality and student skill acquisition. An analysis based on PIRLS-2011 outcomes

This article examines the question of teacher quality and its effects on the skills acquisition of primary school students in Spain. We use an education production function in which we incorporate teachers' fixed effects, estimated by means of a multiple regression model. Specifically, we examine the acquisition of reading skills by drawing on data from PIRLS-2011. The results obtained allow us to conclude that teachers constitute an important input in the acquisition of reading skills. Additionally, we analyse which observed teachers' characteristics can be related to teacher quality. By identifying the quality of each teacher in the sample, we are also able to determine where the "best" and "worst" teachers work. The results indicate that there is a greater probability of finding high quality teachers in privately owned schools and in schools where the students come from families with higher levels of economic and socio-cultural resource

Increasing online shop revenues with web scraping: a case study for the wine sector

Purpose – Wine has been produced for thousands of years and nowadays we have seen a spread in the wine culture. E-commerce sales of wine have increased considerably and online customer’s satisfaction is influenced by quality and price. This paper presents a case study of the company “QuieroVinos, S.L.”, an online wine shop founded in 2015 that sells Spanish wines in two main marketplaces. Design/methodology/approach – With the final target of increasing the company profits it has been designed and developed an application to track the prices of competitors for a set of products. This information will be used to set the product prices in order to offer the products both competitively and profitably in each Marketplace. This application must check, by tacking into account information such as the product cost or the minimum product margin, if it is possible to decrease the price in order to reach the top cheapest position and as a consequence, increase the sales. Findings – The application improved in a notorious way the company’s results in terms of sales and shipping costs. It must be said that without the use of the presented application, performing the price comparison process within each one of the marketplaces would have taken a long time. Moreover, as prices change very frequently, the obtained information has a very limited time value, and the competitors prices should be analyzed daily in order to take accurate decisions regarding the company’s price policy. Originality/value – Although the application has been designed for the wine sector and the two named marketplace, it could be exported to other sectors. For that, it should be implemented new modules to collect information regarding the competitor’s price of the products selling on each corresponding marketplaceThis work was supported by the Ministerio de Economía y Competitividad under contract TIN2017- 84553-C2-2-R. Also, the authors are members of the research group 2017-SGR363, funded by the Generalitat de Catalunya

Numerical simulation of roughness effects on the flow past a circular cylinder

In the present work large eddy simulations of the flow past a rough cylinder are performed at a Reynolds number of Re = 4.2 × 105 and an equivalent sand-grain surface roughness height ks = 0.02D. In order to determine the effects of the surface roughness on the boundary layer transition and as a consequence on the wake topology, results are compared to those of the smooth cylinder. It is shown that surface roughness triggers the transition to turbulence in the boundary layer, thus leading to an early separation caused by the increased drag and momentum deficit. Thus, the drag coefficient increases up to CD 1.122 (if compared to the smooth cylinder it should be about CD 0.3 - 0.5). The wake topology also changes and resembles more the subcritical wake observed for the smooth cylinder at lower Reynolds numbers than the expected critical wake at this Reynolds number.Peer ReviewedPostprint (author's final draft

Parallel Adaptive Mesh Refinement Simulation of the Flow Around a Square Cylinder at Re = 22000

AbstractIn this paper a parallel adaptive mesh refinement for LES simulation of turbulent flows is presented. The AMR scheme applies a cell- based refinement technique to get enough grid-resolution to solve the small scales structures, adapting the mesh according to physics- based refinement criteria. A flexible tree data structure is used to keeping track of the mesh adaptation and an edge-based data structure to save and search cell connectivity. The AMR framework is combined with parallel algorithms for partitioning and balancing of the computational mesh. Numerical results for turbulent flow around a square cylinder at Re = 22000 are compared to experimental data

Numerical analysis of conservative unstructured discretisations for low Mach flows

This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. https://authorservices.wiley.com/author-resources/Journal-Authors/licensing-and-open-access/open-access/self-archiving.htmlUnstructured meshes allow easily representing complex geometries and to refine in regions of interest without adding control volumes in unnecessary regions. However, numerical schemes used on unstructured grids have to be properly defined in order to minimise numerical errors. An assessment of a low-Mach algorithm for laminar and turbulent flows on unstructured meshes using collocated and staggered formulations is presented. For staggered formulations using cell centred velocity reconstructions the standard first-order method is shown to be inaccurate in low Mach flows on unstructured grids. A recently proposed least squares procedure for incompressible flows is extended to the low Mach regime and shown to significantly improve the behaviour of the algorithm. Regarding collocated discretisations, the odd-even pressure decoupling is handled through a kinetic energy conserving flux interpolation scheme. This approach is shown to efficiently handle variable-density flows. Besides, different face interpolations schemes for unstructured meshes are analysed. A kinetic energy preserving scheme is applied to the momentum equations, namely the Symmetry-Preserving (SP) scheme. Furthermore, a new approach to define the far-neighbouring nodes of the QUICK scheme is presented and analysed. The method is suitable for both structured and unstructured grids, either uniform or not. The proposed algorithm and the spatial schemes are assessed against a function reconstruction, a differentially heated cavity and a turbulent self-igniting diffusion flame. It is shown that the proposed algorithm accurately represents unsteady variable-density flows. Furthermore, the QUICK schemes shows close to second order behaviour on unstructured meshes and the SP is reliably used in all computations.Peer ReviewedPostprint (author's final draft

Direct numerical simulation of the turbulent natural convection flow in an open cavity of aspect ratio 4

In this paper, three-dimensional turbulent natural convection heat transfer in an open cavity with an isothermal wall facing the overture has been studied. The aspect ratio chosen for the cavity has been 4 to complement the studies by Trias et al. [1, 2] of closed cavities with the same aspect ratio. Direct numerical simulations (DNS) of the cavity are presented and analyzed. Rayleigh numbers up to Ra = 1012 has been considered.Peer ReviewedPostprint (published version