Defect Analysis and Detection of Cutting Regions in CFRP Machining Using AWJM

The use of composite materials with a polymeric matrix, concretely carbon fiber reinforced polymer, is undergoing further development owing to the maturity reached by the forming processes and their excellent relationship in terms of specific properties. This means that they can be implemented more easily in di erent industrial sectors at a lower cost. However, when the components manufactured demand high dimensional and geometric requirements, they must be subjected to machining processes that cause damage to the material. As a result, alternative methods to conventional machining are increasingly being proposed. In this article, the abrasive waterjet machining process is proposed because of its advantages in terms of high production rates, absence of thermal damage and respect for the environment. In this way, it was possible to select parameters (stand-o distance, traverse feed rate, and abrasive mass flow rate) that minimize the characteristic defects of the process such as taper angle or the identification of di erent surface quality regions in order to eliminate striations caused by jet deviation. For this purpose, taper angle and roughness evaluations were carried out in three di erent zones: initial or jet inlet, intermediate, and final or jet outlet. In this way, it was possible to characterize di erent cutting regions with scanning electronic microscopy (SEM) and to distinguish the statistical significance of the parameters and their e ects on the cut through an analysis of variance (ANOVA). This analysis has made it possible to distinguish the optimal parameters for the process

Paralelización de una aplicación de contorneado automático de imágenes médicas 3D

[ES] Trabajar con grandes cantidades de datos de una manera inadecuada, el acceso a ellos y la manera de realizar los cálculos a la hora de programar puede afectar enormemente y de manera negativa al tiempo de ejecución de cualquier aplicación. Cuando se trata con imágenes médicas para la segmentación automática debemos hacer frente a todos estos problemas, y para solucionarlos vamos a hacer uso tanto de la paralelización de la aplicación entre distintos núcleos de procesamiento, como de la reorganización de código y uso correcto de los datos para conseguir una mejora en el tiempo de cómputo del programa. Por otro lado, se ha intentado abordar el problema del contorneado automático de órganos usando redes neuronales artificiales, prescindiendo de la anterior aplicación para buscar un mayor índice de acierto y proporcionar mejores resultados usando esta tecnología.[EN] Working with large amounts of data in an inadequate form, the access to it and the way to perform calculations when programming can affect enormously and negatively to the time of execution of any application. When it comes to automatic segmentation of medical images we must face all the problems mentioned and solve them, to do that we need to use both the parallelization of the application between different processing cores, and the reorganization of code and the correct usage of data to get an improvement in the computing time of the program. On the other hand, we have tried to solve the problem about automatic segmentation of organs using artificial neural networks without the previous application to get a higher success rate and better results using this technology.Salguero García, P. (2017). Paralelización de una aplicación de contorneado automático de imágenes médicas 3D. http://hdl.handle.net/10251/86669.TFG

On the Machinability of an Al-63%SiC Metal Matrix Composite

This paper presents a preliminary study of aluminium matrix composite materials during machining, with a special focus on their behavior under conventional processes. This work will expand the knowledge of these materials, which is considered to be strategic for some industrial sectors, such as the aeronautics, electronics, and automotive sectors. Finding a machining model will allow us to define the necessary parameters when applying the materials to industry. As a previous step of the material and its machining, an experimental state-of-the-art review has been carried out, revealing a lack of studies about the composition and material properties, processes, tools, and recommended parameters. The results obtained and reflected in this paper are as follows; SiC is present in metallic matrix composite (MMC) materials in a very wide variety of sizes. A metallographic study of the material confirms the high percentage of reinforcement and very high microhardness values registered. During the machining process, tools present a very high level of wear in a very short amount of time, where chips are generated and arcs are segmented, revealing the high microhardness of the material, which is given by its high concentration of SiC. The chip shape is the same among other materials with a similar microhardness, such as Ti or its alloys. The forces registered in the machining process are quite di erent from conventional alloys and are more similar to the values of harder alloys, which is also the case for chip generation. The results coincide, in part, with previous studies and also give new insight into the behavior of this material, which does not conform to the assumptions for standard metallic materials, where the hypothesis of Sha er is not directly applicable. On the other hand, here, cutting forces do not behave in accordance with the traditional model. This paper will contribute to improve the knowledge of the Al-63%SiC MMC itself and the machining behavior

New data on the distribution range of Hemidactylus turcicus in Portugal

En Portugal, la salamanquesa rosada Hemidactylus turcicus solamente está presente en la costa sur y en zonas interiores del sudeste. En este trabajo se describe la existencia de una nueva población que expande la distribución de esta especie por la costa portuguesa. El hallazgo ocurrió en primavera y verano de 2010 durante los inventarios de fauna realizados en una cantera restaurada en Setúbal. La nueva localidad se halla a 70 km de la población más cercana hasta ahora conocida y se especulan dos posibles hipótesis para su aparente aislamiento: (1) un deficiente esfuerzo de prospección en la zona, o (2) una dispersión a larga distancia debida al transporte humano involuntario

New data on the distribution range of Hemidactylus turcicus in Portugal

En Portugal, la salamanquesa rosada Hemidactylus turcicus solamente está presente en la costa sur y en zonas interiores del sudeste. En este trabajo se describe la existencia de una nueva población que expande la distribución de esta especie por la costa portuguesa. El hallazgo ocurrió en primavera y verano de 2010 durante los inventarios de fauna realizados en una cantera restaurada en Setúbal. La nueva localidad se halla a 70 km de la población más cercana hasta ahora conocida y se especulan dos posibles hipótesis para su aparente aislamiento: (1) un deficiente esfuerzo de prospección en la zona, o (2) una dispersión a larga distancia debida al transporte humano involuntario

¿Las implicaciones «negativas» de la identificación social feminista en la identidad laboral? : Relaciones entre los procesos de búsqueda de empleo y las subjetividades feministas.

This paper is an attempt to examine possible tensions between holding a master's degree in feminist studies, and being successful when accessing the labor market. To assess this correlation, different semi-structured interviews with respondents, related to the Master of Feminist Studies at the Complutense University of Madrid, were seen through. Nowadays, gender equality is far up on the social and political agenda but contradicted by the social perception existing around the concept of feminism. As a result, a conflictive relationship between feminist identification and search for employment can be observed. This controversial relationship was analyzed through the particular perceptions and experiences of the respondents to gain insight into how this particular social phenomenon materializes.A través de entrevistas semiestructuradas realizadas a personas relacionadas con el Máster de Estudios Feministas de la Universidad Complutense de Madrid; este texto pretende realizar una aproximación a la forma en que se construye la relación entre una formación feminista y el acceso al mercado laboral. Si bien la igualdad de género se ha instituido como aspiración social relativamente aceptada y compartida, tal asunción choca con el desconocimiento y las ambiguas valoraciones sociales asociadas aún existentes en torno al concepto de feminismo. Esto genera una relación conflictiva entre la identificación feminista y la consecución de empleo. Mediante el análisis de este contexto y de las percepciones y vivencias manifestadas al respecto por las informantes, profundizaremos en la forma y funcionamiento de esta particular intersección social

Influence of AbrasiveWaterjet Parameters on the Cutting and Drilling of CFRP/UNS A97075 and UNS A97075/CFRP Stacks

The incorporation of plastic matrix composite materials into structural elements of the aeronautical industry requires contour machining and drilling processes along with metallic materials prior to final assembly operations. These operations are usually performed using conventional techniques, but they present problems derived from the nature of each material that avoid implementing One Shot Drilling strategies that work separately. In this work, the study focuses on the evaluation of the feasibility of AbrasiveWaterjet Machining (AWJM) as a substitute for conventional drilling for stacks formed of Carbon Fiber Reinforced Plastic (CFRP) and aluminum alloy UNS A97050 through the study of the influence of abrasive mass flow rate, traverse feed rate and water pressure in straight cuts and drills. For the evaluation of the straight cuts, Stereoscopic Optical Microscopy (SOM) and Scanning Electron Microscopy (SEM) techniques were used. In addition, the kerf taper through the proposal of a new method and the surface quality in different cutting regions were evaluated. For the study of holes, the macrogeometric deviations of roundness, cylindricity and straightness were evaluated. Thus, this experimental procedure reveals the conditions that minimize deviations, defects, and damage in straight cuts and holes obtained by AWJM

Combined Manufacturing Process of Copper Electrodes for Micro Texturing Applications (AMSME)

Surface texturing has brought significant improvements in the functional properties of parts and components. Sinker electro discharge machining (SEDM) is one of the processes which generates great texturing results at different scale. An electrode is needed to reproduce the geometry to be textured. Some geometries are difficult or impossible to achieve on an electrode using conventional and even unconventional machining methods. This work sets out the advances made in the manufacturing of copper electrodes for electro erosion by additive manufacturing, and their subsequent application to the functional texturing of Al-Cu UNS A92024-T3 alloy. A combined procedure of digital light processing (DLP) additive manufacturing, sputtering and micro-electroforming (AMSME), has been used to produce electrodes. Also, a specific laboratory equipment has been developed to reproduce details on a microscopic scale. Shells with outgoing spherical geometries pattern have been manufactured. AMSME process has shown ability to copper electrodes manufacturing. A highly detailed surface on a micrometric scale have been achieved. Copper shells with minimum thickness close to 300 mu m have been tested in sinker electro discharge machining (SEDM) and have been shown very good performance in surface finishing operations. The method has shown great potential for use in surfaces texturing.This work has received financial support from Spanish Government (MINECO/AEI/FEDER, Grant Project DPI2017-84935-R

Las voces de la periferia: arquitectura y acción colectiva; un ejemplo de caso

During the most difficult moments of the Covid-19 pandemic various comparisons were drawn between the current crisis and the financial disaster in 2008. In that year, a group of fine arts students developed a participative and activist project in which architecture, understood as a possibility to inhabit and look after, was the emancipatory and enabling impulse for a new type of political and social intervention which originated from the necessity to participate in discussions that consequently arouse from a time of political turmoil. Ever since, LaFábrika detodalavida, the project stemming from the inhabitation and rehabilitation of a derelict cemetery in Los Santos de Maimona (Badajoz), maintains a relation between architecture and social activation through the development of cultural practises of set political connotations. In this retrospective view we try to narrow down the requirements of these kind of projects and their difficulties with regard to the initiation of events and the upkeep of their social and professional relations.; Durante los momentos más difíciles de la pandemia de Covid-19 se establecieron diversas comparaciones entre esta crisis y el desastre financiero de 2008. Aquel año, un grupo de estudiantes de Bellas Artes desarrollaron un proyecto participativo y activista, donde la arquitectura, entendida como una posibilidad de habitar y cuidar, fue el impulso emancipador y posibilitante para un nuevo tipo de intervención política y social, producto de la necesidad de tomar parte en los discursos desplazados consecuentes de un momento de ebullición política. Desde entonces, LaFábrika detodalavida, el proyecto resultante de la ocupación y rehabilitación de una cementera abandonada en Los Santos de Maimona (Badajoz), mantiene una relación entre arquitectura y activación social a través del desarrollo de prácticas culturales de marcadas connotaciones políticas. En esta visión retrospectiva, trataremos de acercarnos a las necesidades de este tipo de proyectos y sus dificultades para la activación de eventos y el cuidado de sus relaciones sociales y profesionales