Variation propagation of bench vises in multi-stage machining processes

Comunicación presentada a MESIC 2019 8th Manufacturing Engineering Society International Conference (Madrid, 19-21 de Junio de 2019)Variation propagation has been successfully modeled by the Stream of Variation (SoV) approach in multistage machining processes. However, the SoV model basically supports 3-2-1 fixtures based on punctual locators and other workholding systems such as conventional vises are not considered yet. In this paper, the SoV model is expanded to include the fixture- and datum-induced variations on workholding devices such as bench vises. The model derivation is validated through assembly and machining simulations on Computer Aided Design software. The case study analyzed shows an average error of part quality prediction between the SoV model and the CAD simulations of 0.26%

Herramientas basadas en indicadores tróficos para la implementación del enfoque ecosistémico en pesquerías con escasez de datos: ejemplos de Argelia y Bahía Bou-Ismail

Over the past decade, the Algerian government has undertaken several incentives financed by state subsidies, via a range of development plans for fishing activities. Although these have led to the growth and modernization of the fishing fleet and the creation of various jobs, this increased fishing pressure has not maximized production as anticipated. In fact, catch is decreasing, and there are clear signs of stock overexploitation for several species, particularly sardines, for which catches have fallen dramatically. This study analyses the impact of fishing from an ecosystem perspective, with a view to the implementation of ecosystem approach to fishery management (EAFM) at the level of Algerian fisheries. To this end, a series of trophic indicators are used. The analysis shows that ecosystems at both national level and in the Bou-Ismail Bay are excessively exploited, and are altered by overexploitation and probably eutrophication. This situation is demonstrated in particular by the decrease in the average trophic level of catch, which is synonymous with “Fishing Down Marine Food Webs” (FDMW).Durante la década pasada, el gobierno argelino puso en marcha varios incentivos de financiación estatal, a través de una serie de planes de desarrollo para actividades pesqueras. A pesar de que este hecho ha originado crecimiento y modernización en la flota pesquera, además de la creación de puestos de trabajo, este aumento de la presión pesquera no ha permitido aumentar la producción pesquera como se había previsto. De hecho, las capturas están decreciendo y hay claros signos de sobreexplotación en varias especies, particularmente la sardina, para la cual las capturas han descendido drásticamente. Este estudio analiza el impacto de la pesca desde una perspectiva ecosistémica, con vistas a implementar el enfoque ecosistémico en la ordenación pesquera argelina. Se utilizan una serie de indicadores tróficos para este fin. El análisis muestra que los ecosistemas están muy explotados, alterados por la sobreexplotación y probablemente eutrofizados, tanto a nivel nacional como en la bahía de Bou-Ismail. Esta situación ha quedado demostrada concretamente por el descenso en el nivel trófico medio de las capturas, que significa la pesca de los niveles inferiores de la cadena trófica marina

Incorporation of form deviations into the matrix transformation method for tolerance analysis in assemblies

Comunicación presentada a MESIC 2019 8th Manufacturing Engineering Society International Conference (Madrid, 19-21 de Junio de 2019)Mathematical models for tolerance representation are used to assess how the geometrical variation of a specific component feature propagates along the assembly, so that tolerance analysis in assemblies can be carried out using a specific tolerance propagation method. Several methods for tolerance analysis have been proposed in the literature, being some of them implemented in CAD systems. All these methods require modelling the geometrical variations of the component surfaces: parametric models, variational models, DoF models, etc. One of the most commonly used models is the DoF model, which is employed in a number of tolerance analysis methods: Small Displacement Torsor (SDT), Technologically and Topologically Related Surfaces (TTRS), Matrix Transformation, Unified Jacobian–Torsor model. However, none of the DoF-based tolerance analysis methods incorporates the effect of form deviations. Among the non DoF-based methods, there are two that include form tolerances: the Vector Loop or Kinematic method and the Tolerance Map (T-Map) model, although the latter is still under development. In this work, a proposal to incorporate form deviations into the matrix transformation method for tolerance analysis in assemblies is developed using a geometrical variation model based on the DoF model. The proposal is evaluated applying it to a 2D case study with components that only have flat surfaces, but the proposal can be extrapolated to 3D cases

A conceptual approach for the design of instruments in education professionals for the evaluation of the competence “Learning to Learn”

En este artículo pretendemos realizar una aproximación al concepto de competencia, centrándonos finalmente en la competencia Aprender a Aprender, objeto de nuestro estudio. Esta aproximación conceptual tiene como finalidad el diseño de instrumentos que nos permitan evaluar dicha competencia en los profesionales de la educación. Para ello, reflexionaremos acerca de los procesos implicados en el desarrollo de la competencia Aprender a Aprender, que se van a evaluar. Esto nos permitirá planificar y diseñar el proceso de evaluación de la competencia Aprender a Aprender.Neste artigo, pretendemos fazer uma abordagem ao conceito de concorrência, finalmente, centrando-se sobre a competência de aprender a aprender, objeto de nosso estudo. Esta abordagem conceptual destina-se a concepção de instrumentos que permitem-nos avaliar essa concorrência nos profissionais da educação. Para este efeito, refletindo sobre os processos envolvidos no desenvolvimento da competência aprender a aprender, avaliaremos. Isso permitir-nos planejar e desenvolver o processo de avaliação da competência aprender a aprender.This paper we intend to make an approach to the concept of competition, finally focusing on competence learn to learning, the object of our study. This conceptual approach is intended tools design that allows us to assess that competence in professionals in education. To do this, we will reflect on the processes involved in the development of competence learn to learning, to be evaluated. This allows us to plan and design the assessment process of competence learns to learning

The cyanobacterial ribosomal-associated protein LrtA from Synechocystis sp. PCC 6803 is an oligomeric protein in solution with chameleonic sequence properties

The LrtA protein of Synechocystis sp. PCC 6803 intervenes in cyanobacterial post-stress survival and in stabilizing 70S ribosomal particles. It belongs to the hibernating promoting factor (HPF) family of proteins, involved in protein synthesis. In this work, we studied the conformational preferences and stability of isolated LrtA in solution. At physiological conditions, as shown by hydrodynamic techniques, LrtA was involved in a self-association equilibrium. As indicated by Nuclear Magnetic Resonance (NMR), circular dichroism (CD) and fluorescence, the protein acquired a folded, native-like conformation between pH 6.0 and 9.0. However, that conformation was not very stable, as suggested by thermal and chemical denaturations followed by CD and fluorescence. Theoretical studies of its highly-charged sequence suggest that LrtA had a Janus sequence, with a context-dependent fold. Our modelling and molecular dynamics (MD) simulations indicate that the protein adopted the same fold observed in other members of the HPF family ( - - - - - ) at its N-terminal region (residues 1–100), whereas the C terminus (residues 100–197) appeared disordered and collapsed, supporting the overall percentage of overall secondary structure obtained by CD deconvolution. Then, LrtA has a chameleonic sequence and it is the first member of the HPF family involved in a self-association equilibrium, when isolated in solution.Ministerio de Economía y Competitividad CTQ2015-64445-RMinisterio de Economía y Competitividad BIO2016-78020-RMinisterio de Economía y Competitividad FIS2014-52212-RMinisterio de Economía y Competitividad BIO2016-75634-PFundación Séneca 19353/PI/1

Differences in the relative roles of environment, prey availability and human activity in the spatial distribution of two marine mesopredators living in highly exploited ecosystems

Aim Identifying the main factors affecting the spatial distribution of marine predators is essential in order to evaluate their distribution patterns, predict the potential impact of human activities on their populations and design accurate management actions. This information is also valuable from a more general management perspective, since marine predators are often considered indicators of habitat quality. In this context, we aimed to determine the degree to which environmental features, prey availability and human activities interact and influence spatial distribution of two marine mesopredator elasmobranchs, the small-spotted catshark (Scyliorhinus canicula) and the Mediterranean starry ray (Raja asterias), living in a highly human-exploited environment. Location Mediterranean Sea. Methods With information obtained from an extended experimental survey we investigated the relative importance of environmental variables, prey availability and human activities on the spatial distribution of the abundance, biomass and occurrence rate of these marine mesopredators using deviance partitioning analyses. Results Our results revealed that environmental variables were the most important factors explaining the spatial distribution of Mediterranean starry ray, whereas small-spotted catshark distribution was also influenced by prey availability and human factors. From a management point of view, these findings suggest that Mediterranean starry ray could be a good candidate as an indicator species of demersal environmental quality. On the other hand, the distribution of the small-spotted catshark, which responds in an interactive and complex way to environment, prey availability and particular human activities, may be misleading as an environmental indicator. Main conclusions The spatial distribution of elasmobranchs in highly human-impacted marine areas can reflect the interactive and combined effects of multiple factors. To avoid misunderstandings, attention should be paid to statistical procedures allowing the separation of pure and joint contribution of the factors driving the observed spatial patternsPeer reviewe

Design of a machine to rectify ceramic tiles for laboratory tests

Ponència presentada a 9th Manufacturing Engineering Society International Conference (MESIC 2021) 23rd-25th June 2021, Gijόn, SpainThe tile rectification process, also called squaring, consists of machining the edges of the tile to make them straight, parallel two by two and perpendicular to the other two in addition to controlling the size of the tile (calibrating). The current industrial lines are based on multiple heads (abrasive wheels) where the characterization of the process in terms of product quality and power consumption is hard to be conducted. In this work we present a laboratory machine equipped with a single grinding wheel to be used for testing and simulating the working conditions of a conventional rectification tile. The specifications of the machine that are required and the analysis of the different functional systems designed (clamping and motion, cutting, cooling, structure/enclosure, and electrical/control system) is reported. This machine may lead researchers to characterize the rectification process and propose actions for improving the efficiency and the sustainability of the industrial process

Evaluar la competencia aprender a aprender: Una propuesta metodológica

En este artículo se presenta un procedimiento para diseñar instrumentos para evaluar la competencia de Aprender a Aprender. Analizamos la secuencia de trabajo y los conceptos implicados. Se trata de una línea de trabajo que pretende diseñar instrumentos de evaluación referidos a estándares, para evaluar las competencias básicas en la educación obligatoria, y las genéricas o transversales en las titulaciones de grado universitarias (el sistema de instrumentos para universitarios se denomina ESCOGE). Se ilustra la reflexión acerca de esta propuesta con la definición teórica realizada para el diseño de instrumentos que permitan evaluar esta competencia en egresados universitarios del área de Ciencias de la Educación (Maestros, Pedagogos, Psicopedagogos y Educadores Sociales), aportando muestras de los elementos útiles para el estudio de evidencias de validación de constructo basada en juicio de expertos

Una aproximación conceptual para el diseño de instrumentos de evaluación de la competencia aprender a aprender en los profesionales de la educación

La competencia de Aprender a Aprender (AaA, en lo sucesivo) ha sido señalada desde hace unos años como una de las competencias clave para el desarrollo personal y social. La formación a lo largo de la vida se basa no sólo en lo que las sociedades avanzadas puedan aportar a sus ciudadanos, sino también en la preparación con que éstos cuenten para aprovechar estas oportunidades. Prevenir la posibilidad de exclusión a lo largo de la vida (fenómeno especialmente doloroso cuando se produce en edades avanzadas, en las que las personas encuentran menos permeabilidad en el mercado de trabajo), es fundamental si se quiere apoyar un modelo de desarrollo social dirigido a promover la Cohesión Social