Recursos de colección

Archivo Digital UPM (107.543 recursos)

This is an institutional repository providing access to the research output of the institution. Primarily contains thesis.

Materia = Física

Mostrando recursos 1 - 20 de 1.560

  1. Passive neutron area monitor with TLD pairs

    Guzmán-García, Karen Arlete; Borja Hernández, C.G.; Valero Luna, C.; Hernández Dávila, V.M.; Vega-Carrillo, Héctor René
    The response of a passive neutron area monitor with pairs of thermoluminescent dosimeters has been calculated using the Monte Carlo code MCNP5. The response was calculated for one TLD 600 located at the center of a polyethylene moderator. The response was calculated for 47 monoenergetic neutron sources ranging from 1E(-9) to 20 MeV. Response was calculated using two irradiation geometries, one with an upper source and another with a lateral source. For both irradiation schemes the response was calculated with the TLD in two positions, one parallel to the source and another perpendicular to the source. The advantage of this passive...

  2. Estudio teórico y numérico del comportamiento acústico de la disolución y crecimiento de nubes de burbujas

    Sañudo Babío, Jaime
    El proyecto trata sobre el estudio teórico y la resolución numérica de una serie de ecuaciones derivadas de las ecuaciones fundamentales de Mecánica de Fluidos. Dichas ecuaciones aplican al estudio del comportamiento o respuesta de burbujas gaseosas que se encuentran en el seno de un líquido. A lo largo del proyecto las propiedades seleccionadas para los cálculos corresponden a burbujas de CO2 sumergidas en agua, y el tamaño de las burbujas estudiado se encuentra en torno a las 100 micras. En el cuarto capítulo, se realiza una explicación teórica a modo de introducción de las ecuaciones generales de partida, a las...

  3. Demography-based adaptive network model reproduces the spatial organization of human linguistic groups

    Capitán Gómez, José Ángel; Manrubia, Susanna
    The distribution of human linguistic groups presents a number of interesting and nontrivial patterns. The distributions of the number of speakers per language and the area each group covers follow log-normal distributions, while population and area fulfill an allometric relationship. The topology of networks of spatial contacts between different linguistic groups has been recently characterized, showing atypical properties of the degree distribution and clustering, among others. Human demography, spatial conflicts, and the construction of networks of contacts between linguistic groups are mutually dependent processes. Here we introduce an adaptive network model that takes all of them into account and successfully...

  4. Analysis of thermionic bare tether operation regimes in passive mode

    Sanmartín Losada, Juan Ramón; Chen, Xin; Sánchez Arriaga, Gonzalo
    A thermionic bare tether (TBT) is a long conductor coated with a low work-function material. In drag mode, a tether segment extending from anodic end A to a zero-bias point B, with the standard Orbital-motion-limited current collection, is followed by a complex cathodic segment. In general, as bias becomes more negative in moving from B to cathodic end C, one first finds space-chargelimited (SCL) emission covering up to some intermediate point B*, then full Richardson-Dushman (RD) emission reaching from B* to end C. An approximate analytical study, which combines the current and voltage profile equations with results from asymptotic studies of the Vlasov-Poisson system for emissive...

  5. Apuntes de Mecánica de Fluidos

    Martín Domingo, Agustín
    Esta publicacion contiene unos apuntes para la parte de Mecánica de Fluidos de las asignaturas de la ETSAM, junto con cierta cantidad de material adicional que excede el ámbito del curso. Aunque está lejos de ser completa y de estar libre de errores, el autor espera sea útil.

  6. Quantum interference of high-order harmonics from mixed gases

    González Fernández, Agustín; Velarde Mayol, Pedro
    We present a theoretical study about the interference of the harmonics generated by a mixture of two gases, He-Ne. Our model is based on the electron quantum paths, a discrete number of electron trajectories, and continuum-bound transitions. A laser with intensity around 1014W/cm2 that interacts with a mixture of gases, He-Ne, produces an interference that is destructive at the low-order harmonics and oscillates between constructive and destructive near to cutoff. This destructive interference at high-order harmonics may be used to explore other transitions, which are currently hidden. At low-order harmonic frequencies, our numerical results are in very good agreement with...

  7. Macroscopic CNT fibres inducing non-epitaxial nucleation and orientation of semicrystalline polymers

    Yue, Hangbo; Monreal-Bernal, Alfonso; Fernández-Blázquez, J. P.; Llorca Martinez, Francisco Javier; Vilatela, J. J.
    In the presence of macroscopic fibres of carbon nanotubes (CNT), various semicrystalline polymers are shown to present accelerated crystallisation through the formation of a transcrystalline (TC) layer perpendicular to the fibre axis. From differential scanning calorimetry, polarized optical microscopy and X-ray diffraction we establish this to be due to much faster nucleation rates at the fibre surface. The formation of a TC layers is demonstrated for polyvinyldene fluoride, isotactic polypropylene and poly(lactic acid) in spite of the large differences in their chemistry and structure unit cells, suggesting that epitaxy in terms of lattice type or size matching is not a prerequisite. For the three polymers as well...

  8. Analytical solution of an afocal two freeform mirror design problem

    Benitez Gimenez, Pablo; Nikolic, Milena; Miñano Dominguez, Juan Carlos
    We investigate a new afocal two freeform mirror design problem in first order optics. The resulting first-order partial differential equations for the freeform two mirror system have an analytic solution with the sole condition that the x-y and x'-y' axes are parallel. Two selected solutions are presented. One of them is emiaplanatic (fulfilling the aplanatic condition only for the x-coordinates), while the other is, to our knowledge, the firstexample of an aplanatic two-mirror system without rotational symmetry.

  9. Cuestionarios conceptuales en Física: evaluación de resultados de aprendizaje y conceptos erróneos en Mecánica y Electromagnetismo = Concept Inventories in Physics: assessment of learning outcomes and misconceptions in Mechanics and Electromagnetism

    Alconchel Pecino, Francisco; Cámara Moral, María Encarnación; Díaz Muñoz, Marcos; Gámez Mejías, Berta; Gámez Mejías, María de Linarejos; Laguna Heras, Maria Fe; Lavín Hueros, Álvaro; Martín Blanquer, Pilar; Ponce Garrés, Ángel; Seidel Gómez de Quero, Luis
    En este trabajo presentamos los resultados de la aplicación de dos cuestionarios conceptuales (FCI, Force Concept Inventory, y BEMA, Brief Electricity and Magnetism Assessment) a estudiantes de primer curso de Grados en Ingeniería en la Universidad Politécnica de Madrid. Hemos utilizado los cuestionarios conceptuales como una herramienta de investigación educativa orientada a identificar fortalezas y debilidades en el perfil de entrada de los alumnos y en los resultados de aprendizaje de las asignaturas de Física General I y II. Además, hemos identificado los errores conceptuales más importantes. Los resultados obtenidos nos permiten dirigir las acciones de innovación educativa a objetivos...

  10. Laser Shock Processing: An Advanced Technique for Improving the Surface and Mechanical Properties of Metallic Alloys

    Ocaña Moreno, José Luis; Porro González, Juan Antonio; Díaz Muñoz, Marcos; Ruiz de Lara de Luis, Leonardo; García Beltrán, Ángel; Santiago Varela, José Antonio; Peral Jiménez, David
    Profiting by the increasing availability of laser sources delivering intensities above 10 9W/cm2 with pulse energies in the range of several Joules and pulse widths in the range of nanoseconds, laser shock processing (LSP) is being consolidating as an effective technology for the improvement of surface and mechanical resistance properties of metals and is being developed as a practical process amenable to production engineering. The main acknowledged advantage of the laser shock processing technique consists on its capability of inducing a relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly, the life improvement...

  11. Descubriendo conceptos erróneos en Física de Primer Curso mediante cuestionarios conceptuales

    Alconchel Pecino, Francisco; Cámara Moral, María Encarnación; Diaz Muñoz, Marcos; Laguna Heras, Maria Fe; Lauzurica Santiago, Sara; Lavin Hueros, Alvaro; Martín Blanquer, Pilar; Seidel Gómez de Quero, Luis
    En este trabajo se presentan los resultados de la aplicación del cuestionario conceptual BEMA (Brief Electricity and Magnetism Assessment) a alumnos de primer curso de Grados de Ingeniería en la Universidad Politécnica de Madrid. Además de obtener resultados cuantitativos globales sobre el perfil de entrada de los alumnos y sobre la evaluación de resultados de aprendizaje en la asignatura Física General II, hemos analizado los cuestionarios para identificar conceptos erróneos en Electricidad y Magnetismo. El uso de los cuestionarios conceptuales como herramienta de investigación educativa, ya muy bien contrastado, es útil además para identificar las carencias concretas en una materia...

  12. Cuestionarios conceptuales en primer curso de grados en Ingeniería como herramienta de investigación educativa

    Alconchel Pecino, Francisco; Cámara Moral, María Encarnación; Casquel del Campo, Rafael; Gámez Mejías, Berta; Gámez Mejías, María de Linarejos; Lavín Hueros, Álvaro; Martín Blanquer, Pilar; Seidel Gómez de Quero, Luis
    En este trabajo presentamos los resultados de la administración del cuestionario conceptual FCI (Force Concept Inventory) a alumnos de primer curso de Grados en Ingeniería de la Universidad Politécnica de Madrid. Hemos utilizado el cuestionario conceptual como una herramienta de investigación educativa orientada a identificar fortalezas y debilidades en el perfil de entrada de los alumnos y en los resultados de aprendizaje de la asignatura de Física General I. Los resultados obtenidos, además de ser contrastados con resultados de otras Universidades de todo el mundo, nos permiten dirigir las acciones de innovación educativa y de cambio metodológico a objetivos mucho...

  13. Wave propagation in soils problems using the Generalized Finite Difference Method

    Benito Muñoz, Juan José; Ureña Prieto, Francisco; Salete Casino, Eduardo; Muelas Rodríguez, Ángel; Gavete Corvinos, Luis Antonio; Galindo Aires, Rubén Ángel
    The consideration of highly irregular topography or heterogeneities and singularities in the domain are necessary for solving a wide variety of seismic problems, e. g. earthquake site studies. Therefore, the use of a meshless method (MM) with the possibility of employing an irregular grid point distribution can be of interest for modeling this kind of problems. The tradition of using Finite Different Methods for modeling seismic wave propagation problems have allowed researches to solve it and, in fact, a numerical model using the geotechnical calculation software FLAC has been used here to validate the results. It is clear the improvement...

  14. Evaluación de la absorción acústica en cámara reverberante

    Pérez Molina, Julio José
    Este Proyecto Fin de Grado describe la manera correcta de realizar la evaluación de absorción acústica mediante la medida del coeficiente de absorción de un determinado material en sala reverberante. De esta manera, observando las exigencias descritas en la Norma UNE-EN ISO 354:2004 [1], se van a realizar las mediciones en la cámara reverberante que se encuentra en la Escuela Técnica Superior de Ingeniería y Sistemas de Telecomunicación de la UPM. Como primer paso, se pretende ajustar la cámara reverberante para las medidas de absorción acústica. Se realizará siguiendo los requisitos establecidos por la norma, atendiendo especialmente a lo indicado en...

  15. Estudio y diseño de difusores piramidales

    Coifman Lucena, Andrea
    Proyecto dedicado al estudio de difusores acústicos con geometría piramidal, a fin de conseguir un prototipo adecuado para la mejora de la calidad acústica de un recinto. Está dividido en tres partes: teoría, estudio y diseño. En la primera parte, se ha procedido a hacer un estudio teórico del concepto de difusión acústica, así como, de los difusores acústicos que ayudan a mejorar las características de la difusión, centrándonos en la actuación de los difusores con geometría piramidal. Al final de esta primera parte, se estudia cómo predecir la difusión de estos elementos. En la segunda parte, se entra en el estudio de...

  16. Induction of through-thickness compressive residual stress fields in thin Al2024- T351 plates by laser shock processing

    Ocaña Moreno, José Luis; Correa Guinea, Carlos; Porro González, Juan Antonio; Díaz Muñoz, Marcos; Ruiz de Lara de Luis, Leonardo; Peral Jiménez, David
    Purpose - With the aid of the calculational system developed by the authors, the analysis of the problem of laser shock processing (LSP) treatment for induction of residual stress (RS) fields for fatigue life enhancement in relatively thin sheets in a way compatible with reduced overall workpiece deformation due to spring-back self-equilibration has been envisaged. Numerical results directly tested against experimental results have been obtained confirming the critical influence of the laser energy and irradiation geometry parameters. The paper aims to discuss these issues. Design/methodology/approach - Plane rectangular specimens (160mm×100mm×2mm) of Al-cladded (-80µm) Al2024-T351 were considered both for LSP experimental...

  17. A dynamical systems perspective on the absence of debris associated with the disappearance of flight MH370

    García Garrido, Víctor; Mancho, Ana María; Wiggins, Stephen; Mendoza Parra, Carolina Andrea
    The disappearance of Malaysia Airlines flight MH370 on the morning of 8 March 2014 is one of the great mysteries of our time. Perhaps the most relevant aspect of this mystery is that not a single piece of debris from the aircraft was found during the intensive surface search carried out for roughly 2 months following the crash. Difficulties in the search efforts, due to the uncertainty of the plane's final impact point and the time that had passed since the accident, bring the question on how the debris scattered in an always moving ocean, for which there are multiple...

  18. Supervivencia de una amarra espacial en órbita baja

    Negrete Solana, Juan José
    Electrodynamic tethers are a tool to deorbit dead satellites in LEO. These satellites can be shattered by an impact with space debris thereby increasing the amount of space debris and eventually triggering the Kessler cascade. In the LEO environment the tethers can be rendered inoperative by bombardment by space debris or micrometeoroids. In this report we study the survival probability of a tape-tether against multiple impacts with debris. In particular a FORTRAN program which computes the survival probability of a 5 km long, 2 cm wide and 0.05 mm thick tether orbiting at 800 km altitude during 3 months is presented....

  19. Apuntes de Análisis Vectorial

    Martín Domingo, Agustín
    Esta publicacion está basada en unos apuntes para la parte de campos escalares y vectoriales de las asignaturas de la ETSAM y de la titulación de Ingeniero en Geodesia y Cartografía. Además, se ha añadido otro material extra a lo largo del tiempo, por lo que el contenido actual es más amplio que el correspondiente a dichas asignaturas. Sin embargo, espero que muchas de las partes sean aún bastante útiles.

  20. Crystallographically uniform arrays of ordered (In) GaN Nanocolumns

    Gacevic, Zarko; Bengoechea Encabo, Ana; Albert, Steven; Torres Pardo, Almudena; González Calbet, José María; Calleja Pardo, Enrique
    In this work, through a comparative study of self-assembled (SA) and selective area grown (SAG) (In)GaN nanocolumn (NC) ensembles, we first give a detailed insight into improved crystallographic uniformity (homogeneity of crystallographic tilts and twists) of the latter ones. The study, performed making use of: reflective high energy electron diffraction, X-ray diffraction and scanning electron microscopy, reveals that unlike their SA counterparts, the ensembles of SAG NCs show single epitaxial relationship to both sapphire(0001) and Si(111) underlying substrates. In the second part of the article, making use of X-ray diffraction, we directly show that the selective area growth leads to...

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