956 research outputs found

    The mean-variance model from the inverse of the variance-covariance matrix

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    In this paper we obtain the main results of the Markowitz mean-variance model from the inverse of the covariance matrix, following a shorter and mathematically rigorous path. We also obtain the equilibrium expression of Sharpes capital asset pricing model (CAPM).capm, beta, portfolio composition

    Disseny d'un captador solar d'alta temperatura, amb motor Stirling i disc parabòlic

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    Els objectius del projecte entren dins de diversos camps de l‚Äôenginyeria, els principals s√≥n la mec√†nica, construcci√≥, termodin√†mica, electricitat,... a continuaci√≥ es mostra la llista d‚Äôobjectius establerts per a la realitzaci√≥ del projecte. ‚Äź Realitzar el disseny d‚Äôun Captador Solar d‚ÄôAlta Temperatura amb motor Stirling ‚Äź Disseny √≤ptim de la parab√≤lica ‚Äź Dissenyar el sistema de seguiment solar ‚Äź Plantejar els dispositius el√®ctrics necessaris i la seva programaci√≥ ‚Äź Fer un disseny inicial del motor Stirling per a una posterior millora ‚Äź Fer un estudi dels possibles empla√ßaments on obtindr√≠em un alt rendiment Com es pot observar a dalt, aquest projecte pret√©n fer el disseny d‚Äôun primer captador solar, un prototip, amb el qual es podrien realitzar les primeres proves de forma emp√≠rica, aquestes ens permetrien guanyar experi√®ncia i optimitzar el sistema per poder fer‚Äźlo del tot rentable al mercat. Aquesta experi√®ncia √©s clau per a la construcci√≥ del dispositiu final, ja que a diferencia d‚Äôaltres sistemes o altres motors, aquest encara t√© una producci√≥ molt baixa i el secretisme de les empreses que ho fan √©s absolut

    Study of 2-D Photonic Band Gaps for NIR applications

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    Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2016, Tutors: Albert Romano i Mauricio MorenoThis work consists of the study and characterisation of the photonic band gaps (PGB) for different 2D-crystal structures. It has run with a simulating software called Optiwave. We are going to use two methods to study photonic crystals, the Finite-difference time-domain method (FDTD) and the Plane wave expansion method (PWE). This study has been focus on square and hexagonal lattice formed by dielectric cylinders in water, thus one of the important parameters is the ratio radius-to-pitc

    Mau! (A propòsit d'Això del català, d'Albert Pla Nualart)

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    Quality and financial model in public universities

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    Assuming that a unique model of university quality doesn’t exist, this article considers different models with their advantages and disadvantages. In this article we manifest the implications of each quality model with its sources of funding, paying special attention to the most recent reports from European, Spanish and Catalan universities about what would be the best funding for the university model they defend

    Algunos Inocybe de la zona alpina de los Pirineus de Catalunya, II

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    In this second contribution, 12 species and one variety of Inocybe are described (including iconography) and discussed. /. alboperonata K√ľhner, I. hum ilis (1. Favre et Horak) Esteve-Rav. et Vila comb. nov., I. johannae K√ľhner and I. luteipes 1. Favre f mixtipes Esteve-Rav. et Vila ad int., are new records in the funga1 catalogue of Iberian peninsula.En esta segunda aportaci√≥n al estudio del g√©nero Inocybe en la zona alpina de los Pirineos catalanes se describen, comentan e iconografian 12 especies y una variedad, de las cuales I. alboperonata K√ľhner, I. hum ilis (J. Favre et Horak) Esteve-Rav. et Vila comb. nov., I.johannae K√ľhner y I. luteipes 1. Favre f mixtipes Esteve-Rav. et Vila ad int., representan nuevas aportaciones al catalogo micol√≥gico peninsular

    Digital Learners in Scientific Literature: Design and Implementation of a Systematic Review from 2001 to 2010

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    En la √ļltima d√©cada han surgido numerosas denominaciones que tratan de definir a una nueva generaci√≥n de estudiantes. Una generaci√≥n digital que ha crecido rodeada de tecnolog√≠a y que, supuestamente, poseen unas caracter√≠sticas comunes y diferenciadas de las anteriores. El objetivo de este art√≠culo es analizar la evoluci√≥n y la relaci√≥n de estas denominaciones en la literatura cient√≠fica. Para ello, se muestra el proceso de construcci√≥n de una herramienta y el dise√Īo de una estrategia para la revisi√≥n sistem√°tica de esta tem√°tica en los art√≠culos publicados en ISI Web of Science entre 2001 y 2010, as√≠ como los principales resultados.In the last decade have emerged numerous denominations that seek to define a new generation of students. A digital generation that has grown up surrounded by technology and supposedly therefore has common and distinct characteristics. The aim of this paper is to investigate the evolution and the relationship of these denominations in the scientific literature. For this purpose, a tool and a strategy is built and designed for the systematic review of this subject in articles published in ISI Web of Science from 2001 to 2010, and the main results are shown.Ministerio de Educaci√≥n (Espa√Īa) PR20100394Ministerio de Ciencia e Innovaci√≥n (Espa√Īa) EDU2008-0147
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