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Fused filament fabrication or fused deposition modeling (FFF/FDM) has as one of its main restrictions the surface quality intrinsic to the process, especially linked to the layer thickness used during manufacture. The purpose of this paper is to study the possibility of improving the surface quality of polylactic acid (PLA) parts manufactured by FFF using the shot blasting technique.

The influence of corundum blasting on 0.2 mm layer thickness FDM PLA parts treated with two sizes of abrasive, different exposure times and different incidence pressures.

As a result, improvements of almost 80% were obtained in the surface roughness of the pieces with high exposure times, and more than 50% in just 20 s.

This technique is cheap, versatile and adaptable to different part sizes and geometries. Furthermore, it is a fast and environmentally friendly technique compared to conventional machining or vapor smoothing. Despite this, no previous studies have been carried out to improve the quality of this technology.

This paper aims to explore the perceptions of preservice teachers regarding their learning during the teaching practicum (TP) period in the context of the pandemic. Specifically, the objectives of this study are to analyze the difficulties and the learning consequences perceived by student teachers and also to identify proposals with which to improve the initial teacher education (ITE) during the TP period in times of uncertainty and crisis.

This study used a mixed-methods approach. The participants consisted of 89 preservice teachers (student teachers). An online questionnaire was used to collect data during January 2022 in two rounds. The data analysis was carried out from an integrative perspective and used both a descriptive approach and the content analysis of the participants’ narratives.

The results show the differences, adjustments and adaptations that have had to be implemented in schools as a whole. The findings also highlight the difficulties that the pandemic context has caused for the TP period in schools and the relevant implications that it has had on ITE during these past two academic years.

This research is relevant for a better understanding of the challenges faced during the pandemic in the field of early childhood and primary education. More specifically, this paper gives important clues to higher education institutions on how to carry out TP, especially in times of uncertainty and crisis.

The purpose of this study is to determine the perception of graduates from teaching degree programs in Early Childhood and Primary Education carried out in Spain in accordance with the European Higher Education Area, who are currently working in classrooms, on their initial training in the educational treatment of diversity (ETD). In addition, potential differences were examined based on the teaching degree that was studied (Early Childhood or Primary).

This study used a mixed methodology including an ad hoc questionnaire and a semi-structured interview. Participants were 140 working teachers who had previously earned their degree in Early Childhood or Primary Education programs. Data analysis was carried out from an integrative perspective, using a basic descriptive focus and content analysis.

The results reveal that the new teachers considered that their initial training in the area of ETD was not as extensive as it should have been and as required by their daily teaching needs. They felt that they had acquired better education in the theoretical content as compared to the practical component. They mentioned a lack of training to attend to students entering the system at a later stage as well as for those with high intellectual abilities, noting that the initial training in ETD focused excessively on deficits and not enough on potentialities and other student diversities.

This study may be useful as it offers an improved adaptation to the reality of early education in ETD classrooms of future teachers, both for the competent education administrations and universities. It may also serve as a starting point to adjust the permanent training offer for teachers to their specific needs, making up for the deficiencies of their initial training.

This paper aims to study the interfacial and interlayer bonding of Polylactic acid parts manufactured by fused deposition modelling. Different layer thicknesses are analysed in the manufacture of these pieces and the lack of material associated with this parameter is verified. The influence of the immersion of these parts in different solvents is also studied, as they are increasingly used in the improvement of the surface finish. Tomography results are also obtained in which the increase in density of the parts subjected to these treatments is demonstrated.

The material used in this study is a 1.75-mm diameter polylactic acid (PLA) filament from fused filament fusion world. Monolayer and multilayer samples have been manufactured. The manufactured parts were subjected to solvent immersion for a period of 60 s. The solvents used are chloroform (CHCl3), dichloromethane (CH2Cl2), tetrahydrofuran (C4H8O) and ethyl acetate (C4H8O2). The pieces were then dried for 48 h. The interior of the samples was evaluated by two techniques: microscopy and tomography.

With this study, it has been observed that the thickness of the layer affects the porosity interfacial to a greater extent than in the interlayer, causing the increase in porosity as this thickness is increased.The impact of different chemical treatments (immersions in different solvents) on the internal quality of the parts has been evaluated. All the solvents analysed soften the surface as they cause the softening of the material and its possible redistribution. In the interior, however, they affect in a lighter way. The retention of solvents in the porosity of the pieces is also checked, especially pronounced in the areas close to the surface. Finally, changes are observed in the density of the pieces, related to the partial crystallization of the samples.

All that has been studied shows that the application of chemical post-processes not only affects the surface texture of the parts, or the less studied mechanical properties, but also affects the interfacial union of the parts in a very different way. This is the first study carried out on this aspect with polylactic acid (PLA) and post-processing methods.

Existing studies are scarce, especially on the Industry 4.0 application to firms' innovation and competitiveness, and even more on the application to LATAM and Spanish SMEs. This paper tries to fill this gap by explaining the results of applying a systematic model, to understand which are the SMEs' strengths and weaknesses in relation to the Industry 4.0 transformation.

A systematic methodology involving documentation analysis, visits to the companies, interviews with employees and managers, making a preliminary diagnosis, crossing their needs with the enablers that can apply. The fieldwork was carried out during a two month period (2019), on a target sample of 22 SMEs operating under industrial productive activity already exporting or planning their internationalization toward LATAM regions.

There are relevant barriers that need to be overcome in order to enter Industry 4.0 and, in this specific analysis, the following major classification was obtained: (1) Technological barrier, (2) Training barrier, (3) Economic barrier and (4) Contextual barrier.

This paper provides new insights and sets a starting point regarding LATAM and Spanish’ Industry 4.0 situation, while contributing to the SMEs competitiveness by providing deeper understanding of the barriers and limitations in adopting Industry 4.0, pointing out some implications and suggestions for organizations to implement.

Los estudios existentes son escasos, especialmente sobre la aplicación de la Industria 4.0 a la innovación y competitividad de las empresas, y más aún sobre la aplicación a las PYMEs de LATAM y españolas. Este trabajo trata de llenar este vacío explicando los resultados de un modelo sistemático, para entender cuáles son sus fortalezas y debilidades en la transformación hacía la Industria 4.0.

Este modelo sistemático involucra el análisis de documentación, visitas a las empresas, entrevistas con empleados y directivos, realizando un diagnóstico previo, cruzando sus necesidades con los habilitadores que pueden aplicar. El trabajo de campo se ha realizado durante un periodo de dos meses (2019), sobre una muestra potencial de 22 PYMEs que operan bajo actividad productiva industrial y que ya exportan o planean su internacionalización hacia las regiones de LATAM.

Existen barreras relevantes que deben ser superadas para implementar la Industria 4.0 y, en este análisis específico, se identificaron: (1) Barreras tecnológicas; (2) Barreras formativas; (3) Barreras económicas; y (4) Barreras contextuales.

Este trabajo proporciona nuevas perspectivas y establece un punto de partida sobre la situación de la Industria 4.0 en las PYMEs LATAM y españolas, apoyando la competitividad al proporcionar una comprensión más profunda de las barreras y limitaciones en su implementación, al tiempo que señala algunas implicaciones y sugerencias para las organizaciones a implementar.

Autopoiesis is a concept originally used to define living systems. However, no measure for autopoiesis has been proposed so far. Moreover, how can we build systems with a higher autopoiesis value? The paper aims to discuss these issues.

Relating autopoiesis with Ashby’s law of requisite variety, self-organization is put forward as a way in which systems can be designed to match the variety of their environment.

Guided self-organization has been shown to produce systems which can adapt to the requisite variety of their environment, offering more efficient solutions for problems that change in time than those obtained with traditional techniques.

Being able to measure autopoiesis allows us to apply this measure to all systems. More “living” systems will be fitter to survive in their environments: biological, social, technological, or urban.

In any distributed application, the communication between the distributed processes/nodes of the distributed systems is essential for both reliability and efficiency matters. The purpose of this paper is to address this issue for distributed applications based on JXTA protocols aiming at extending and evaluating the protocols of the JXTA library for reliable P2P computing.

After a careful examination of the current version of JXTA protocols, the need was observed for improving the original JXTA protocols such as pipe services to ensure reliable communication between nodes of the grid platform and the discovery and presence service to increase the performance of the applications. Using a mixed P2P network based on broker peers and client peers architecture, which served as a basis to extend the JXTA protocols, was the basis of the approach.

The original JXTA protocols are extented/re‐implemented to support the development of reliable P2P distributed applications.

The proposed approach has been validated in practice by deploying a P2P network using nodes of PlanetLab platform and testing each of the re‐implemented protocols using this real P2P network. The extended JXTA protocols can be used to develop reliable P2P distributed applications.

Is of value by showing how to improve both efficiency reliability of JXTA protocols and services.

The purpose of this work is to investigate the similarity requirements for the application of multifidelity modeling (MFM) for the prediction of airfoil dynamic stall using computational fluid dynamics (CFD) simulations.

Dynamic stall is modeled using the unsteady Reynolds-averaged Navier–Stokes equations and Menter's shear stress transport turbulence model. Multifidelity models are created by varying the spatial and temporal discretizations. The effectiveness of the MFM method depends on the similarity between the high- (HF) and low-fidelity (LF) models. Their similarity is tested by computing the prediction error with respect to the HF model evaluations. The proposed approach is demonstrated on three airfoil shapes under deep dynamic stall at a Mach number 0.1 and Reynolds number 135,000.

The results show that varying the trust-region (TR) radius (λ) significantly affects the prediction accuracy of the MFM. The HF and LF simulation models hold similarity within small (λ ≤ 0.12) to medium (0.12 ≤ λ ≤ 0.23) TR radii producing a prediction error less than 5%, whereas for large TR radii (0.23 ≤ λ ≤ 0.41), the similarity is strongly affected by the time discretization and minimally by the spatial discretization.

The findings of this work present new knowledge for the construction of accurate MFMs for dynamic stall performance prediction using LF model spatial- and temporal discretization setup and the TR radius size. The approach used in this work is general and can be used for other unsteady applications involving CFD-based MFM and optimization.

El presente trabajo indaga acerca del estado actual de la legislación de alojamiento turístico bajo la modalidad de apartamentos turísticos y viviendas de uso turístico en España.

Se trata de una investigación exploratoria centrada en el análisis de una tipología específica dentro del subsector hospedaje. Se basa en un trabajo de gabinete (recopilación bibliográfica y normativa).

Como resultado, se advierte que la legislación de alojamiento turístico bajo la modalidad de apartamentos y viviendas de uso turístico en España ha experimentado un creciente desarrollo en la última década y presenta un importante nivel de dispersión, un alto grado de heterogeneidad en los criterios de categorización, y en algunos casos falta de incorporación de aspectos claves como la accesibilidad, la calidad y la sostenibilidad.

La originalidad del estudio se fundamenta en el análisis comparativo de la regulación que las Comunidades Autónomas realizan de esta modalidad de alojamiento turístico denominada en la mayoría de las normativas analizadas de apartamentos turísticos y viviendas de uso turístico. El trabajo comprende un estudio actualizado de la legislación autonómica en la materia.