Recursos de colección

Archivo Digital UPM (106.121 recursos)

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

Materia = Telecomunicaciones

Mostrando recursos 1 - 20 de 3.416

  1. Análisis de la oferta de sistemas de información integrados (ERP) y diseño de una metodología para su selección

    Torres de Gabriel, Jorge
    El presente trabajo está vinculado al sector de las Tecnologías de la Información y la Comunicación, las cuales pueden definirse como el estudio, diseño, desarrollo, implementación, soporte y administración de los sistemas de información, particularmente aplicaciones de software y hardware de ordenadores. Por un lado, el mercado de las Tecnologías de la Información y la Comunicación está en constante desarrollo y por otro, las empresas generan una gran cantidad de datos que va aumentando de forma exponencial. Motivo por el cual es importante que las empresas dispongan de algún tipo de sistema (de información) que sea capaz de procesar los...

  2. Collaborative tools: computer science students' skills versus software industry needs

    Medina-Domínguez, Fuensanta; Sánchez-Segura, María Isabel; Moreno Sánchez-Capuchino, Ana María; Santín, Daniel
    Software companies encourage and further the use of collaborative tools and skills at the workplace in pursuit of the benefits of their use: they improve communication, productivity and efficiency, and competitiveness. Besides, undergraduate and graduate software engineering computing curricula recommend subjects related to effective cooperative working and group learning. In order to align industry needs and curricula recommendations, universities should provide students with the collaborative knowledge and skills that they will require on the labour market once they finish their degrees. In this scenario, we asked three questions: Are collaborative tools beneficial to software projects? Is it easier for students...

  3. Controlling the degradation of wireless sensor networks

    Rozas Cid, Alba; Blesa Martínez, Javier; Romero Perales, Elena; Araujo Pinto, Álvaro
    With the fast expansion of Wireless Sensor Networks (WSNs) and the increasing emergence of new scenarios and applications, extending their lifetime is crucial. Usually, WSN developers use generic algorithms and deployment arrangements without considering the specific needs of their network's application. Taking this application into account can result in a significant enhancement of performance, both in terms of increasing the lifetime and improving the quality of service (QoS). Furthermore, most WSN developers do not consider the final behavior of the network when nodes are nearly depleted and resources are scarce. In this paper we introduce the concept of the controlled...

  4. Solutions of general linear difference equations, nested sums and applications

    Abderraman Marrero, Jesús Carmelo; Tomeo Perucha, Venancio
    The equivalence between the celebrated combinatorial and determinantal representations for the solutions of linear difference equations with variable coefficients, of both n-th and unbounded order, is considered. A more explicit representation is proposed using determined nested sums of their variable coefficients, which enables us to manage adequately all the sum of products involved in the previous representations. Some particular applications are also outlined.

  5. Infinite invertible arrowhead matrices and applications

    Abderraman Marrero, Jesús Carmelo; Tomeo Perucha, Venancio
    Motivated by current applications of the arrowhead matrices of large order, the infinite invertible arrowhead matrices are considered. A method based on a simple but suitable triangular factorization is proposed for obtaining, in the finite-dimensional case, a decomposition of the inverse in O(n) time. This procedure can be applicable to infinite arrowhead matrices factored properly. Some illustrative examples are given.

  6. Monolithic integration of a high power semiconductor master oscillator power amplifier

    Faugeron, Mickael; Vilera Suárez, Mariafernanda; Pérez Serrano, Antonio; Garcia Tijero, Jose Manuel; Esquivias Moscardo, Ignacio; Perez Hugalde, Carlos; Krakowski, Michel; Van Dijk, Frédéric
    We present a high power semiconductor Master Oscillator Power Amplifier monolithically integrated on InP, which includes a modulation section. This device can be used for random-modulation-continuous wave lidar systems or free-space communications.

  7. High power three-section integrated master oscillator power amplifier at 1.5 μm

    Faugeron, Mickael; Vilera Suárez, Mariafernanda; Krakowski, Michel; Robert, Yannick; Vinet, Eric; Primiani, Peppino; Le Goëc, Jean-Pierre; Parillaud, Olivier; Pérez Serrano, Antonio; García Tijero, Jose Manuel; Kochem, Gerd; Traub, Martin; Esquivias Moscardo, Ignacio; Van Dijk, Frédéric
    We present the design and the performance of a monolithically integrated master oscillator power amplifier at 1.5 μm. The three-section device includes a distributed feedback laser, a modulation section, and a high power tapered amplifier. In order to mitigate the coupling effects of the light reflected at the facets, the device has been designed with a bent longitudinal axis and a tilted front facet. The device delivers >400 mW mode-hopping free output power. In static regime, the modulation section allows an extinction ratio of 35 dB.

  8. Wavelength jumps and multimode instabilities in integrated master oscillator power amplifiers at 1.5 mu m: experiments and theory

    Pérez Serrano, Antonio; Vilera Suárez, Mariafernanda; Javaloyes, Julien; García Tijero, Jose Manuel; Esquivias Moscardo, Ignacio; Balle, Salvador
    We analyze the large (>10 nm) and abrupt jumps in emission wavelength, together with the multimode instabilities associated with them, which are observed in monolithically integrated master oscillator power amplifiers emitting at 1.5 μm. The physical origin of such phenomena is investigated in the framework of a travelling-wave model which phenomenologically incorporates thermal effects via self and cross-heating of the different sections of the device. The occurrence of the wavelength jumps and the instabilities as a function of the injected currents in the two sections is interpreted in terms of a thermally tuned competition between the modes of the master...

  9. Emission characteristics of a 1.5-mu m all-semiconductor tapered master oscillator power amplifier

    Vilera Suárez, Mariafernanda; Pérez Serrano, Antonio; Garcia Tijero, Jose Manuel; Esquivias Moscardo, Ignacio
    We present experimental results on the emission characteristics of a 1.5-_m distributed feedback (DFB) tapered master oscillator power amplifier (MOPA) in a wide range of steady-state injection conditions, showing different dynamical behaviors. A detailed analysis of the optical and radio-frequency spectra has allowed the identification of three different emission regimes: i) stable amplified DFB emission, but with wavelength jumps when sweeping the injection currents; ii) multimode Fabry–Perot (FP) operation of the complete MOPA cavity; and iii) self-pulsed operation at frequencies between 5 and 8 GHz. The quasi-periodic occurrence of these emission regimes as a function of the injected currents is...

  10. A survey on future railway radio communications services: challenges and opportunities

    Moreno García-Loygorri, Juan; Riera Salis, José Manuel; Haro Ariet, Leandro De; Rodríguez, Carlos
    Radio communications is one of the most disruptive technologies in railways, enabling a huge set of value-added services that greatly improve many aspects of railways, making them more efficient, safer, and profitable. Lately, some major technologies like ERTMS for high-speed railways and CBTC for subways have made possible a reduction of headway and increased safety never before seen in this field. The railway industry is now looking at wireless communications with great interest, and this can be seen in many projects around the world. Thus, railway radio communications is again a flourishing field, with a lot of research and many...

  11. Analysis of complexity and modulation spectra parameterizations to characterize voice roughness

    Moro Velázquez, Laureano; Gómez García, Jorge Andrés; Godino Llorente, Juan Ignacio
    Disordered voices are frequently assessed by speech pathologists using acoustic perceptual evaluations. This might lead to problems due to the subjective nature of the process and due to the in uence of external factors which compromise the quality of the assessment. In order to increase the reliability of the evaluations the design of new indicator parameters obtained from voice signal processing is desirable. With that in mind, this paper presents an automatic evaluation system which emulates perceptual assessments of the roughness level in human voice. Two parameterization methods are used: complexity, which has already been used successfully in previous works,...

  12. Design of maintenance structures for rural electrification with solar home systems. The case of the Moroccan program

    Carrasco Moreno, Luis Miguel; Martín Campos, F.J.; Narvarte Fernandez, Luis; Ortuño, M.T.; Vitoriano, B.
    In decentralised rural electrification through solar home systems, private companies and promoting institutions are faced with the problem of deploying maintenance structures to operate and guarantee the service of the solar systems for long periods (ten years or more). The problems linked to decentralisation, such as the dispersion of dwellings, difficult access and maintenance needs, makes it an arduous task. This paper proposes an innovative design tool created ad hoc for photovoltaic rural electrification based on a real photovoltaic rural electrification program in Morocco as a special case study. The tool is developed from a mathematical model comprising a set...

  13. Characterisation and efficiency test of a li-ion energy storage system for PV systems

    Makivar Puente, Aitor; Narvarte Fernández, Luis
    Li-ion batteries are modern electrical energy storage systems which are undergoing an intense development in their technological features. Their high specific energy, efficiency and durability, together with the lowering of their production costs, are placing them as one of the most promising actors in the field of electrical energy storage technology used as tool for integrating renewable energy sources. But due to the fact that they are in an early stage of development, their reliability must be trusted. This paper describes a method and the results for testing round trip efficiencies of a modern Li-ion battery based energy storage system...

  14. Influence of polarization on keyhole probability on a MIMO-OFDM train-to-wayside system on tunnels

    Moreno García-Loygorri, Juan; Haro Ariet, Leandro de; Rodríguez, Carlos; Cuéllar Navarrete, Luis; Riera Salis, Jose Manuel
    This paper presents a deep insight on a real implementation of a train-to-wayside broadband radio on subway tunnels that makes use of a 2x2 MIMO-OFDM setup. A keyhole is a phenomenon that usually happens in tunnels and that seriously degrades channel?s capacity, even if both transmitter and receiver antennas are uncorrelated. The main purpose of this paper is to study in detail the influence of the polarization in the probability of having a keyhole on a MIMOOFDM train-to-wayside communication system on a tunnel. MIMO keyholes are studied in four different polarization setups, six different tunnels cross-sections and, finally, capacity results...

  15. Low-cost measurement for a secondary Mode S radar transmitter

    Parra Cerrada, Ángel; González Posadas, Vicente; Jiménez Martín, José Luis; Blanco del Campo, Álvaro; Hernández Perdomo, Wilmar; Calderón Cordova, Carlos
    A low-cost, multiple-purpose, and high-precision timing test setup for the measurements of secondary Mode S radar transmission signal was proposed. The goal was to fully guarantee compliance of the proposed transmitter under test with the really hard International Civil Aircraft Organization requirements using traditional measurement equipment, which was difficult or even impossible to ensure up to now. The low-cost structure proposed in this paper allows the user to perform measurements independently of the measurements performed by the pieces of test equipment shelled by the manufacturer of radar, which is a very important aspect since the independence of the verifications is a mandatory requirement...

  16. Aplicación de comparativa de smartphones

    Lage Vázquez, Iván
    Este documento se corresponde con el Proyecto de Fin de Máster (PFM) correspondiente a la titulación de Máster en Ingeniería Web por la Universidad Politécnica de Madrid, cuyo autor es Iván Lage Vázquez y siendo tutelado por el profesor Jesús Bernal Bermúdez. En este PFM desarrollamos una aplicación web que, como bien versa el título, tiene como objetivo ofrecer una funcionalidad principal que consiste en comparar características técnicas de teléfonos inteligentes o más conocidos como smartphones. Detrás de esta funcionalidad principal se encuentra una web 2.0 cuyos contenidos se nutren de la comunidad de usuarios que hacen uso de la aplicación. Entre estas funcionalidades podemos...

  17. Dispositivo LoRa de comunicación a largo alcance y bajo consumo energético para aplicaciones del ámbito del desarrollo

    Rodríguez Munca, José Daniel
    Teniendo en cuenta los avances en innovación tecnológica, se han desarrollado estándares inalámbricos abiertos de bajo consumo energético, alto radio de cobertura y bajo costo como respuesta a las tendencias y necesidades del mercado del IoT como lo es el estándar LoRAWAN (LoRa Alliance, 2016). Sin embargo, es necesario adaptar su uso para aplicaciones del ámbito del desarrollo debido a que el uso de la tecnología apropiada puede ser la clave en el aseguramiento de los servicios básicos que sustentan redes de infraestructuras como agua potable, comunicaciones, electricidad, saneamiento, entre otros; mejorando la calidad de la vida de las personas...

  18. Analysis of the performance of tapered semiconductor optical amplifiers: role of the taper angle

    García Tijero, Jose Manuel; Vilera Suárez, Mariafernanda; Pérez Serrano, Antonio; Esquivias Moscardo, Ignacio; Borruel, Luis
    The role of the taper angle in the performance of tapered semiconductor optical amplifiers emitting at 1.57 um is analyzed by means of simulations with a self-consistent steady state electro-optical and thermal simulator. The results indicate that the self-focusing caused by carrier lensing is delayed to higher output powers for devices with taper angle slightly higher than the free diffraction angle and therefore a higher power with beam quality is attainable with these devices at the expenses of a lower efficiency

  19. IBES/ Iniciativa de Barrios Emergentes y Sostenibles. Herramientas aplicadas para la regeneración de áreas vulnerables. Caso de estudio-aplicación en Cancino Adentro, Santo Domingo Este.

    Navarro de Corcuera, Lucía
    Enfocada para la región de Latinoamérica y el Caribe surgió en 2010 la Iniciativa Ciudades Emergentes y Sostenibles (ICES) por el Banco Interamericano de Desarrollo (BID) que, desde un enfoque multisectorial, propone el desarrollo de las ciudades interviniendo en la sostenibilidad ambiental, urbana, fiscal y de gobernabilidad. El trabajo presente adapta el ICES para llevar su aplicación a la escala de barrio, centrándose en los aspectos que contempla la habitabilidad y el territorio, apostando por intervenciones no asistencialistas y más orientadas a la innovación. IBES constituye un conjunto de herramientas de asistencia técnica para los ayuntamientos municipales que les ayude en...

  20. Emission characteristics of 1.5 um monolithically integrated master oscillator power amplifiers

    Vilera Suárez, Mariafernanda
    El presente trabajo es un estudio de las características de emisión de los láseres de semiconductor Master-Oscillator Power-Amplifier (MOPAs) monolíticos para su uso en aplicaciones que requieren simultáneamente alto brillo y alta pureza espectral. Se han estudiado dos tipos de láseres en el rango de emisión comprendido entre 1540 nm y 1580 nm: MOPAs comerciales de dos secciones y MOPAs de tres secciones específicamente diseñados para su uso como emisores en un sistema LIDAR de absorción diferencial. El análisis espectral de los dispositivos de dos secciones reveló la aparición de inestabilidades espectrales indeseadas en un rango amplio de condiciones de...

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