Recursos de colección

Archivo Digital UPM (109.118 recursos)

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

Estado = En Prensa

Mostrando recursos 1 - 20 de 57

  1. Enabling an Anatomic View to Investigate Honeypot Systems: A Survey

    Fan, Wenjun; Du, Zhihui; Fernández Cambronero, David; Villagra González, Victor Abraham
    A honeypot is a type of security facility deliberately created to be probed, attacked and compromised. It is often used for protecting production systems by detecting and deflecting unauthorized accesses. It is also useful for investigating the behaviour of attackers, and in particular, unknown attacks. For the past 17 years much effort has been invested in the research and development of honeypot based techniques and tools and they have evolved to become an increasingly powerful means of defending against the creations of the blackhat community. In this paper, by studying multiple honeypot systems, the two essential elements of honeypots - the...

  2. A Novel SDN based Stealthy TCP Connection Handover Mechanism for Hybrid Honeypot Systems

    Fan, Wenjun; Fernández Cambronero, David
    Honeypots have been largely used to capture and investigate malicious behavior through deliberately sacrificing their own resources in order to be attacked. Hybrid honeypot architectures consisting of frontends and backends are widely used in the research area, specially due to the benefits of their high scalability and fidelity for detailed attacking data collection. A hybrid honeypot system often needs a facility aimed to tightly control the network traffic, for purposes such as redirecting the traffic from the frontends to the backends for in-depth attack analysis. However, the current traffic redirection approaches, particularly the TCP connection handover mechanisms, are not stealthy and...

  3. MoocCast: Evaluating Mobile Screencast for Online Courses

    Tabuenca, Bernardo; Kalz, Marco; Löhr, Ansje
    The progressive adoption of smartphones and interconnected devices is inspiring students to redesign their physical spaces towards a seamless shift between daily life and learning activities. In the last years, Massive Open Online Courses (MOOCs) represent one of the key resources facilitating universal access to education as they enable students to learn across formal and informal contexts. However, there is little research exploring these alternative ways to present the content offered to learners in MOOCs for improved accessibility from personal contexts. This work presents the first study evaluating mobile-screencast technology as a means to facilitate learning processes in online courses....

  4. Monolithic Interconnected Modules (MIM) for High Irradiance Photovoltaic Energy Conversion: a Comprehensive Review

    Datas Medina, Alejandro; García-Linares Fontes, Pablo
    Monolithic Interconnected Modules (MIM) are densely packed arrays of series interconnected photovoltaic (PV) cells that are manufactured on the same semiconductor substrate. This review presents the result of a prospective study whose objective is to provide an overview of the historical development and current state of the art of the MIM technology. The most outstanding works from the conception of the first MIM devices in the late 70s to the most recent ideas to date, including all relevant milestones achieved during these four decades, are reported. This review focuses on MIM devices that are designed for high-irradiance photovoltaic (HIPV) applications,...

  5. La construcción modular ligera con módulos tridimensionales, antecedentes y situación actual

    Ovando Vacarezza, Graciela; Lauret Aguirregabria, Benito; Pérez-Pujazón Millán, Belén; Catañeda Vergara, Estéfana
    La industrialización de la vivienda ha sido a lo largo de los años una meta a alcanzar en distintos países por los agentes involucrados en la arquitectura. Las razones de éxito y fracaso de los métodos de prefabricación pueden ser claramente comprendidos en el estudio de la evolución de su historia. En este paper se expondrán los antecedentes y la situación actual de la construcción industrializada con módulos tridimensionales ligeros por ser el sistema de mayor grado de industrialización. La construcción con módulos tridimensionales ligeros es poco conocida entre los arquitectos y escasamente publicada en la literatura técnica, a pesar de que...

  6. Simple mathematical approach to solar cell/panel behavior based on datasheet information

    Pindado Carrion, Santiago; Cubas Cano, Javier
    new explicit mathematical expression is used to describe the behavior of a photovoltaic device (solar cell/panel), that is, its I-V curve, based on the characteristic points normally included in the manufacturers’ datasheets. This expression consists of two simple equations, one for voltage levels lower than the voltage at the maximum power point, V < Vmp, and the other one for voltage levels above this point, V > Vmp. The first equation is defined with two of the three characteristic points (short circuit and maximum power points), whereas the second one is defined with the current and voltage levels at maximum...

  7. Impact of extended contact co-firing on multicrystalline silicon solar cell parameters

    Peral Boiza, Ana; Dastgheib-Shirazi, Amir; Fano, Vanesa; Jimeno, Juan Carlos; Hahn, Giso; Cañizo Nadal, Carlos del
    During the temperature spike of the contact co-firing step in a solar cell process, it has been shown that the concentration of lifetime-killer dissolved metallic impurities increases, while adding an annealing after the spike getters most of the dissolved impurities towards the phosphorus emitter, where they are less detrimental. The contact co-firing temperature profile including the after-spike annealing has been called extended contact co-firing, and it has also been proposed as a means to decrease the emitter saturation current density of highly doped emitters, benefiting thus a wide range of materials in terms of detrimental impurity content. The aim of the present...

  8. Analysis of tether-mission concept for multiple flybys of moon Europa

    Sanmartín Losada, Juan Ramón; Charro, Mario; Garret, Henry B.; Sánchez Arriaga, Gonzalo; Sánchez Torres, Antonio
    All four giant planets, far from the Earth and sun and having deep gravitational wells, present propulsion and power mission issues, but they also have an ambient plasma and magnetic field that allows for a common mission concept. Electrodynamic tethers can provide propellantless drag for planetary capture and operation down the gravitational well, and they can generate power to use along with or be stored for inverting tether current. The design for an alternative to NASA’s proposed Europa mission is presented here. The operation requires the spacecraft to pass repeatedly near Jupiter, for greater plasma density and magnetic field, raising a radiation-dose issue that...

  9. Modeling and simulation of upper brachial plexus injury

    Destarac Eguizabal, Marie Andre; Garcia Cena, Cecilia Elisabet; Saltaren Pazmiño, Roque Jacinto; Reyes Urbina, Monica J.; Lopez Lopez, Javier; Espinoza Gomez, Ricardo
    This paper presents the first musculoskeletal model and simulation of upper plexus brachial injury. From this model is possible to analyse forces and movement ranges in order to develop a robotic exoskeleton to improve rehabilitation. The software that currently exists for musculoskeletal modeling is varied and most have advanced features for proper analysis and study of motion simulations. Whilst more powerful computer packages are usually expensive, there are other free and open source packages available which offer different tools to perform animations and simulations and which obtain forces and moments of inertia. Among them, Musculoskeletal Modeling Software was selected to...

  10. Inorganic Photovoltaics - Planar and Nanostructured Devices

    Ramanujam, J.; Verma, A.; González-Díaz, B.; Guerrero-Lemus, R.; Cañizo Nadal, Carlos del; García-Tabarés, E.; Rey-Stolle Prado, Ignacio; Granek, F.; Korte, L.; Tucci, M.; Rath, J.; Singh, U.P.; Todorov, T.; Gunawan, O.; Rubioara, S.S.; Plaza, J.L.; Dieguez, E.; Hoffmann, B.; Christiansen, S.; Cirlin, G.E.
    Since its invention in the 1950s, semiconductor solar cell technology has evolved in great leaps and bounds. Solar power is now being considered as a serious leading contender for replacing fossil fuel based power generation. This article reviews the evolution and current state, and potential areas of near future research focus, of leading inorganic materials based solar cells, including bulk crystalline, amorphous thin-films, and nanomaterials based solar cells. Bulk crystalline silicon solar cells continue to dominate the solar power market, and continued efforts at device fabrication improvements, and device topology advancements are discussed. III-V compound semiconductor materials on c-Si for...

  11. Ti/Pd/Ag Contacts to n-Type GaAs for High Current Density Devices

    Huo, Pengyun; Rey-Stolle Prado, Ignacio
    The metallization stack Ti/Pd/Ag on n-type Si has been readily used in solar cells due to its low metal/semiconductor specific contact resistance, very high sheet conductance, bondability, long-term durability, and cost-effectiveness. In this study, the use of Ti/Pd/Ag metallization on n-type GaAs is examined, targeting electronic devices that need to handle high current densities and with grid-like contacts with limited surface coverage (i.e., solar cells, lasers, or light emitting diodes). Ti/Pd/Ag (50 nm/50 nm/1000 nm) metal layers were deposited on n-type GaAs by electron beam evaporation and the contact quality was assessed for different doping levels (from 1.3 × 1018 cm−3 to 1.6 × 1019 cm−3) and annealing temperatures...

  12. Effect of Sb on the quantum efficiency of GaInP solar cells

    Barrigón Montañés, Enrique; Barrutia Poncela, Laura; Ochoa Gómez, Mario; Rey-Stolle Prado, Ignacio; Algora del Valle, Carlos
    The energy bandgap of GaInP solar cells can be tuned by modifying the degree of order of the alloy. In this study, we employed Sb to increase the energy bandgap of the GaInP and analyzed its impact on the performance of GaInP solar cells. An effective change in the cutoff wavelength of the external quantum efficiency of GaInP solar cells and an effective increase of 50 mV in the open-circuit voltage of GaInP/Ga(In)As/Ge triple junction solar cells were obtained with the use of Sb. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Calentamiento del fango en un digestor anaerobio mediante la aplicación de Energía Solar

    Garcia Corchero, David
    El objetivo de la presente investigación consiste en estudiar el aprovechamiento solar para el calentamiento de los fangos en los digestores anaerobios mediante agua caliente circulando en el interior de un serpentín que rodea la superficie de dicho digestor, como alternativa a los métodos convencionales del calentamiento de fangos como la resistencia eléctrica o el intercambiador de calor mediante la energía obtenida por el gas metano producido en la digestión anaerobia. Se utilizaron 3 digestores, dos de los cuales se calentaron con agua caliente en el interior de un serpentín procedente de un sistema de calentamiento de agua con colectores solares...

  14. The challenge of sustainable building renovation: assessment of current criteria and future outlook

    Pombo Rodilla, Olatz; Rivela Carballal, Beatriz; Neila Gonzalez, Francisco Javier
    Artículo publicado en un número especial dedicado a la sostenibilidad. Se realiza un análisis crítico de las evaluación de la sostenibilidad en la rehabilitación y se plantea la perspectiva futura en este ámbito.

  15. Demonstration of the operation principles of intermediate band solar cells at room temperature

    López Estrada, Esther; Datas Medina, Alejandro; Ramiro Gonzalez, Iñigo; García-Linares Fontes, Pablo; Antolín Fernández, Elisa; Artacho Huertas, Irene; Martí Vega, Antonio; Luque López, Antonio; Shoji, Y.; Sogabe, T.; Ogura, A.; Okada, Y.
    In this work we report, for the first time at room temperature, experimental results that prove, simultaneously in the same device, the two main physical principles involved in the operation of intermediate band solar cells: (1) the production of sub-bandgap photocurrent by two optical transitions through the intermediate band; (2) the generation of an output voltage which is not limited by the photon energy absorption threshold. These principles, which had always required cryogenic temperatures to be evidenced all together, are now demonstrated at room temperature on an intermediate band solar cell based on InAs quantum dots with Al0.3Ga0.7As barriers.

  16. Thermal shields for heat loss reduction in Siemens-type CVD reactors

    Ramos Cabal, Alba; Valdehita Torija, Javier; Zamorano Saavedra, Juan Carlos; Cañizo Nadal, Carlos del
    The use of thermal shields to reduce radiation heat loss in Siemens-type CVD reactors is analyzed, both theoretically and experimentally. The potential savings from the use of the thermal shields is first explored using a radiation heat model that takes emissivity variations with wavelength into account, which is important for materials that do not behave as grey bodies. The theoretical calculations confirm that materials with lower surface emissivity lead to higher radiation savings. Assuming that radiation heat loss is responsible for around 50% of the total power consumption, a reduction of 32.9% and 15.5% is obtained if thermal shields with constant emissivities...

  17. Deposition reactors for solar grade silicon: a comparative thermal analysis of a Siemens reactor and a fluidized bed reactor

    Ramos Cabal, Alba; Filtvedt, W.O.; Lindholm, D.; Ramachandran, P.A.; Rodríguez, A.; Cañizo Nadal, Carlos del
    Polysilicon production costs contribute approximately to 25-33% of the overall cost of the solar panels and a similar fraction of the total energy invested in their fabrication. Understanding the energy losses and the behaviour of process temperature is an essential requirement as one moves forward to design and build large scale polysilicon manufacturing plants. In this paper we present thermal models for two processes for poly production, viz., the Siemens process using trichlorosilane (TCS) as precursor and the fluid bed process using silane (monosilane, MS).We validate the models with some experimental measurements on prototype laboratory reactors relating the temperature profiles...

  18. Lealtad de la marca de la bebida "AQUARIUS" = "AQUARIUS" beverage brand loyalty

    Vargas Perez, Ana Maria; Esteban Curiel, Javier de
    Desde la disciplina del marketing, esta monografía de investigación pretende estudiar cuál es el nivel de lealtad de la marca de la bebida “Aquarius”. Para ello, se ha aplicado la técnica de la encuesta a una muestra aleatoria de 100 estudiantes de la Facultad de Ciencias de la Comunicación del Campus de Fuenlabrada de la Universidad Rey Juan Carlos de Madrid. Los resultados encontrados en este trabajo indican que “Aquarius” se mantiene todavía relacionada con las bebidas reconstituyentes, con una percepción en torno a la salud, con un alto grado de recomendación, y con un nivel de lealtad relativamente medio. = From...

  19. Optical in situ calibration of Sb to grow disordered GaInP by MOVPE

    Barrigón Montañés, Enrique; Barrutia Poncela, Laura; Rey-Stolle Prado, Ignacio
    Reflectance anisotropy spectroscopy (RAS) was employed to determine the optimal specific molar flow of Sb needed to grow GaInP with a given order parameter by MOVPE. The RAS signature of GaInP surfaces exposed to different Sb/P molar flow ratios were recorded, and the RAS peak at 3.02 eV provided a feature that was sensitive to the amount of Sb on the surface. The range of Sb/P ratios over which Sb acts as a surfactant was determined using the RA intensity of this peak, and different GaInP layers were grown using different Sb/P ratios. The order parameter of the resulting layers...

  20. On the layout of a least weight single span structure with uniform load. Some comments and improvements

    Cervera Bravo, Jaime; Vázquez Espí, Carlos; Vázquez Espí, Mariano
    Beghini et al (Struct Multidisc Optim doi:10.1007/s00158-013-1030-6, 2013) have published a very interesting paper arriving to practically the same nearly optimal solutions for the so named “bridge prob- lem” that the Writers published a year before, but using an alternative and remarkable approach to the problem. In spite of this general agreement, the Writers think that some details of the paper can be improved and there are results that can be given a clear and mean- ingful interpretation thanks to an old and practically unknown theorem on optimal slenderness.

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