Event horizon in a compact binary coalescence

Màster Oficial d'Astrofísica, Física de Partícules i Cosmologia, Facultat de Física, Universitat de Barcelona, Curs: 2019-2020, Tutor: Roberto EmparanIn this work we introduce a general method, mostly analytical with relatively simple numerics, for obtaining the event horizon in a compact binary coalescence in which one of the components is a supermassive black hole with a mass much greater than its companion's. We not only reproduce previous literature but also go beyond it by not restricting the smaller object to be a black hole. We apply this procedure to study the mergers of the large black hole with: (a) a Schwarzschild black hole, (b) a charged black hole, (c) a charged singularity and (d) several models of neutron stars. For the uncharged black hole, we recover the exact results in the literature using a slightly different method for solving (numerically) the equations. For the charged case, our results agree qualitatively with the results for the event horizon in the neutral case. For the charged singularity, we find that a \hole" (not a black hole) appears in the event horizon, due to the repulsive gravitational effect of the singularity, which we argue is physically pathological. For neutron stars, we discover that the structure of the merger depends on their compactness: above a certain threshold, the supermassive black hole induces the formation of a black hole inside the star, thus making the merger to happen \inside-out" in a phenomenon that we have named \precursory collapse". Our study of the mergers between neutron stars and black holes has given rise to an article that we have submitted for publicatio

Dynamical binaries in star clusters

To explain both the dynamics of a globular cluster and its production of gravitational waves from coalescing binary black holes, it is necessary to understand its population of dynamically-formed binaries. We provide a theoretical understanding of this population, benchmarked by direct $N$-body models. We find that clusters on average have only one dynamically-assembled binary at any given time. This is different from theoretical expectations and models of binary populations, which predict a larger number of binaries ($\sim 5$), especially for low-$N$ clusters ($\sim 100$), or in the case of two-mass models, low number of black holes. We argue that the presence of multiple binaries is suppressed by a high rate of binary-binary interactions, which efficiently ionise one of the binaries involved. These also lead to triple formation and potentially gravitational wave (GW) captures, which may provide an explanation for the recently reported efficiency of binary black hole mergers with non-zero ($\gtrsim 0.01$) eccentricity in low-mass clusters.Comment: 12 pages, 16 figures, submitted to MNRA

Estudio de los Portafolios en el Practicum: An álisis de un PLE - Portafolio

The specialized literature agrees to notice that even existing some conditions, it is not a generalized methodology at universities. In the new grades and knowledge areas is found the subject of external practices that would be able to show conditions for using the portfolios. Whereas, there are some questions in the educational area: What conditions exist for the use of the portfolios in the Practicum of the education grades in Spain? What level of utilization are evident? What problems of understanding, the students express about the documentation of evidences in portfolios? The research performs a mixed methodology: a first quantitative study with descriptive methodology, interview to 31 coordinators of Practicum of all grades in 10 (20%) Faculty of Education, along with a qualitative study and content analysis of 256 Practicum guides of all grades of 36 (72%) Faculties of Education of public universities in Spain. A second case study, perform a content analysis of 592 annotations of 212 students to show and evaluate the evidences in ePortfolios of the Practicum of the degree of Pedagogy. The results reveal that there are 11 students per tutor 2,88h medium for tutoring and assess ePortfolios. Being mail (between 37.77% and 46.66%) followed by the platforms most used technologies. The eRúbricas and video annotations help document the evidence, however, students still show difficulties in some competencesFunded by Spanish Plan of R+D+i Excellence (2014-16) No. EDU2013-41974P. Project entitled: “Study of the Impact of Federated eRubrics on Assessing Competences in the Practicum”. http://goo.gl/u07aN

Predictive Methodology for Quality Assessment in Injection Molding Comparing Linear Regression and Neural Networks

The use of recycled polypropylene in industry to reduce environmental impact is increasing. Design for manufacturing and process simulation is a key stage in the development of plastic parts. Traditionally, a trial-and-error methodology is followed to eliminate uncertainties regarding geometry and process. A new proposal is presented, combining simulation with the design of experiments and creating prediction models for seven different process and part quality output features. These models are used to optimize the design without developing additional time-consuming simulations. The study aims to compare the precision and correlation of these models. The methods used are linear regression and artificial neural network (ANN) fitting. A wide range of eight injection parameters and geometry variations are used as inputs. The predictability of nonlinear behavior and compensatory effects due to the complex relationships between this wide set of parameter combinations is analyzed further in the state of the art. Results show that only Back Propagation Neural Networks (BPNN) are suitable for correlating all quality features in a single formula. The use of prediction models accelerates the optimization of part design, applying multiple criteria to support decision-making. The methodology is applied to the design of a plastic support for induction hobs. Furthermore, this methodology has demonstrated that a weight reduction of 27% is feasible. However, it is necessary to combine process parameters that differ from the standard ones with a non-uniform thickness distribution so that the remaining injection parameters, material properties, and dimensions fall within tolerances

Comparing Cosmopolitan Discourses Across Sexual Landscapes: Montreal’s Gay Village and Mile End District

Gay spaces have long been a part in the urban landscape of major metropolitan areas in advanced capitalist societies. These urban forms were largely produced in the 1970s and 1980s as safe spaces where LGBTQ individuals could go to escape societal homophobia. In the following decades, these neighbourhoods underwent major urban restructuring associated with broader neoliberal processes of city remaking. In the beginning of the 2000s, a new wave of studies began correlating the neoliberal urban restructuring of gaybourhoods to the production of cosmopolitan spaces. The cosmopolitan discourse has been a driving force in the remaking of major metropolitan areas that wish to attract capital and compete in a global market formed by creative and diversified cities. According to contemporary literature on creative cities, gay neighbourhoods are an essential component in any global city, as they represent diversity and progressiveness. Alongside traditional gay neighbourhoods, new patterns of intra-urban migration among LGBTQ individuals led to the formation of neighbourhoods where sexual identities are not the main marker of the space but queer individuals are welcomed and an active part of the neighbourhood's life. Queer-friendly neighbourhoods are now a reality in the landscapes of major metropolitan areas. In the case of Montreal, the city’s queer-friendly neighbourhood (Mile End) is also home to a creative, young and middle-class population, marking it also as a cosmopolitan space. This research interrogates and compares what kind of cosmopolitan discourses residents of both the gay Village and the Mile End are enacting, producing and performing. The findings of this research indicate that cosmopolitanism is indeed being performed and actively (re)shaping both neighbourhoods. To what extent and what kind of cosmopolitan discourse is employed differs from one space to another and is directly liked to other social and spatial process such as gentrification, safety and urban sexual identities

El rock y el metal en el aula de primaria como recurso didáctico

Treball Final de Grau en Mestre o Mestra d'Educació Primària. Codi: MP1040. Curs acadèmic: 2017/2018La educación primaria es una etapa donde los maestros nos hemos de valer de muchos recursos atractivos para paliar las dificultades de aprendizaje que presentan algunos alumnos. En el presente documento reflexionaremos sobre el uso de la música heavy metal como recurso empleado para la didáctica, ya no solo musical, sino de otras áreas del currículum como la literatura o la historia. Lo haremos a través de una unidad didáctica implementada en la estancia en prácticas en dos clases de 5º de primaria con 24 y 21 alumnos/as respectivamente. Una UD concebida para demostrar que, a través de este estilo de música minoritario y muchas veces marginado socialmente, podemos conseguir buenos resultados en el aula. Los datos obtenidos nos permiten establecer algunas conclusiones tales como que mediante canciones de heavy metal los alumnos son capaces de memorizar poemas de forma sencilla, son capaces de aumentar sus calificaciones a la hora de interpretar una canción con la flauta dulce o comprenden mejor la historia del Quijot

Biomecânica da articulação interfalângica proximal-nativa versus artroplástica

Mestrado em Engenharia MecânicaA presente dissertação teve como principal objetivo o estudo de aspetos biomecânicos da articulação interfalângica proximal da mão, mais precisamente as alterações induzidas pela artroplastia, quando comparado com a articulação no estado nativo. Numa primeira etapa realizou-se uma análise detalhada dos aspetos anatómicos, biomecânicos, patológicos e respetivos tratamentos da articulação com especial enfoque no processo artroplástico desta. Posteriormente, desenvolveram-se os modelos geométricos das estruturas ósseas envolvidas e respetivos implantes com base na digitalização destas estruturas físicas. Na fase posterior desenvolveram-se os modelos numéricos de elementos finitos da condição da articulação nativa e protésica. Os modelos representativos da condição protésica simularam duas situações de interface entre o implante e o osso, por forma a representar duas condições cirúrgicas distintivas, uma representativa de um estado pós cirúrgico e a outra de um estado de médio-longo termo, onde é suposto uma boa ancoragem do implante ao osso. Nestes modelos foram analisados e comparados os estados de deformação no osso, estabilidade do implante e os níveis de tensão no implante para as diferentes condições de carga. De seguida, desenvolveram-se modelos experimentais da articulação com recursos a modelos ósseos especificamente desenvolvidos para o efeito, constituídos por um corpo interior em espuma, replicando a estrutura de osso esponjoso, e uma casca externa em resina epóxi reforçada com fibra de vidro, replicando a estrutura de osso cortical. Estes modelos foram instrumentados com extensómetros nas suas superfícies por forma a avaliar os estados de deformação na sua condição nativa e artroplástica para duas condições de carga distintas representativas de atividades diárias da mão, avaliando-se assim a alterações de transferência de carga no córtex. Os resultados dos modelos numéricos foram comparados com os experimentais, obtendo-se uma boa correlação entre estes. As deformações nas falanges quer nos modelos numéricos, quer experimentais, demonstram uma clara alteração na transferência de carga entre o modelo nativo e o artroplástico. Observou-se um aumento das deformações no osso esponjoso na condição pós-cirúrgica, alterações que estão diretamente relacionadas ao risco de falência do osso por sobrecarga localizada associada a um efeito de fadiga por ação de cargas cíclicas. Na condição de médio-longo termo, o risco identificado está associado a uma redução das deformações nas regiões ósseas vizinhas do implante, relativamente à condição nativa, e pode associar-se este efeito de stressshielding a um potencial risco de reabsorção óssea a termo. Conclui-se assim que a artroplastia da articulação interfalângica proximal altera de forma relevante o comportamento biomecânico das falanges, aportando riscos de origens distintas que eventualmente podem ser minorados por um otimização da geometria e materiais do implante e limitação da condições de carga a impor à articulação num estado pós-cirúrgico.The main objective of this work was the study of biomechanical aspects of the proximal interphalangeal joint of the hand, specifically the changes induced by arthroplasty, when compared with the joint in the native state. The first step was the accomplishment of a detailed a detailed analysis of the anatomical aspects, biochemical, pathological and respective treatments of the joint with special focus on artroplastic process. After, iwere developed the geometric models of the bone structures involved and their respective implants based on the scanning of these physical structures. Posteriorly, were developed the numerical finite element models of the condition of native and prosthetic joint. Representative models of the prosthetic condition simulate two interface conditions between the implant and the bone in order to represent two distinctive surgical conditions, one refers to a post-surgical state and the other refers to a state of medium to long term, in which is supposed a good anchorage of the implant to the bone. In these models were analyzed and compared deformation states of the bone, the implant stability and the implant voltage levels for different load conditions. Then, were developed experimental models of the joint, through the resource of bone models developed specifically for this purpose, constituted by an inner foam body, replicating the cancellous bone structure, and an outer shell epoxy resin reinforced with fiberglass, replicating cortical bone structure. These models were instrumented with strain gauge on their surfaces, in order to evaluate the deformation states in its native condition and in its arthroplasty condition for two different load conditions that represents daily activities using the hand, evaluating thus the charge transfer changes in the cortex.. The results of numerical models were compared with the experimentals, yielding a good correlation between them. The deformation of the phalanges in the numerical models and in the experimental models, shows a clear change in charge transfer between the native and the artroplastic. There was an increase of deformations in the cancellous bone in post-surgical condition, these changes are directly related to the risk of failure of bone through a located overhead associated with a fatigue effect of the cyclic loading action. In the condition of medium-long term, the identified risk is associated with a reduction of the deformations in the surrounding bone regions of the implant relative to the native condition, and this stress-shielding effect can be associated with the potential risk of bone resorption term. It is therefore concluded that the arthroplasty proximal interphalangeal joint changes the biomechanical behavior of the phalanges, bringing risks of different origins that can possibly be alleviated by optimizing the geometry and implant materials and limiting loading conditions to the joint in a postsurgical state

Sustainable supply chain management: The influence of disposal scenarios on the environmental impact of a 2400 L waste container

This paper analyzes the influence of the supply chain management on the environmental impact of a 2400 L waste disposal container used in most cities of Spain. The studied functional unit, a waste disposal container, made up mostly of plastic materials and a metallic structure, and manufactured in Madrid (Spain), is distributed to several cities at an average distance of 392 km. A life cycle assessment of four different scenarios (SC) has been calculated with the software EcoTool v4.0 (version 4.0; i+: Zaragoza, Spain, 2015) and using Ecoinvent v3.0 database (version 3.0; Swiss Centre for Life Cycle Inventories: St. Gallen, Switzerland, 2013). The environmental impact has been characterized with two different methodologies, recipe and carbon footprint. In order to reduce the environmental impact, several end of life scenarios have been performed, analyzing the influence of the supply chain on a closed-looped system that increases recycling. Closed loop management of the waste and reuse of parts allows companies to stop selling products and start selling the service that their products give to the consumers

Life cycle assessment of a plastic part injected with recycled Polypropylene: a comparison with alternative virgin materials

Plastics recycling is becoming a common action to reduce our products and processes'' environmental impact, and it is of the utmost importance to introduce circular economy strategies. However, for most of the different types of thermoplastics, recycling is not currently its usual end of life due to the technical difficulties in the sorting and recycling processes. This paper presents the complete life cycle assessment of an industrial component made with three different thermoplastics; two virgin thermoplastics typically used for similar parts in the market as Polyamide 6 and Polypropylene, and an alternative source of 100% recycled Polypropylene. All life cycle stages are included in the study. After carrying out the life cycle inventory, calculations of the environmental impact of each life cycle steps have been performed with ReCiPe 2016 EndPoint (H/A) v1.03/World and with IPCC 2013 GWP 100a v1.03 methodologies, comparing all three materials under the same conditions. A sensibility assessment has also been performed, calculating a worst-case scenario of the recycled material, and considering higher material acquisition distances. This study shows that recycled Polypropylene contributes to reducing the overall environmental impact of the component life cycle by 29.8% under ReCiPe, and by 42.8% under Carbon Footprint when compared to virgin Polypropylene. For the worst-case scenario, these reductions in the environmental impact of the component life cycle are also significant: 23.2% and 36.4%, respectively, showing that the use of recycled polymers is a key approach to reduce the environmental impact of plastic components

Influence of mechanical design on the evolution of the environmental impact of an induction hob

Purpose: This paper studies the influence of the mechanical design of five different induction hob generations (G1 to G5), which are currently installed in several million homes, on the evolution of their environmental impact. Methods: Life cycle assessment (LCA) has been applied using SimaPro 8.0.3.14 and EcoInvent v2.2 database. Samples of each design were obtained to generate a life cycle inventory. These induction hobs have been developed and produced in Zaragoza (Spain). The functional unit has been defined as all of the components influenced by the mechanical design of a cooktop with four induction hobs and a width of 60 cm, including every component except the electronic boards and the use phase, as they are not affected by the mechanical design. The limits of the LCA model include the production of the raw materials and energy, the manufacture and production processes, the distribution, and the end of life. Results and discussion: This study has revealed that the differences in mechanical design highly affect the environmental impact, especially in the environmental categories of abiotic depletion and human toxicity due to the consumption of copper, steel, and plastics. The manufacturing phase highly affects human toxicity, mainly due to the variation in PPS use. There is a decreasing tendency in the environmental impact from the first (G1) to the last generation (G5), as G5 causes the lowest burden in 8 out of 11 analysed categories. The different generations analysed in this paper show that the compact designs of induction hobs help to decrease the environmental impact, especially thanks to the reduction in wiring lengths. It is also important to enhance the wiring separation at the end-of-life phase, avoiding designs that hinder recycling processes. Conclusions: Compact designs and reduced wiring lengths help to reduce the environmental impact. The consumption of copper, steel, aluminium, and polymers creates considerable impact, although the end-of-life phase reduces the burden created by metals, thanks to recycling. Manufacturing processes such as injection moulding also produce a noteworthy impact, especially in ozone layer depletion due to the inclusion of solvents in EcoInvent’s injection moulding dataset. The impact caused by the distribution phase for this product is almost negligible in most categories