Archivo Digital UPM
This is an institutional repository providing access to the research output of the institution. Primarily contains thesis.
Materia = Electrónica
Mostrando recursos 1 - 20 de 699
Optical digital chaos cryptography - Arenas Pingarrón, Álvaro; González Marcos, Ana; Rivas Moscoso , José Manuel; Martín Pereda , José Antonio
In this work we present a new way to mask the data in a one-user communication system when direct sequence - code division multiple access (DS-CDMA) techniques are used. The code is generated by a digital chaotic generator, originally proposed by us and previously reported for a chaos cryptographic system. It is demonstrated that if the user's data signal is encoded with a bipolar phase-shift keying (BPSK) technique, usual in DS-CDMA, it can be easily recovered from a time-frequency domain representation. To avoid this situation, a new system is presented in which a previous dispersive stage is applied to the...
Using Buildroot for building Embedded Linux Systems - Ruiz González, Mariano
This document describes the basic steps to developed and embedded Linux-based system using the BeagleBoard. The document has been specifically written to use a BeagleBoard development system based on the OMAP `processor.
Optical bistable devices as sensing elements - González Marcos, Ana; Hurtado Villavieja , Antonio; Martín Pereda , José Antonio
The nonlinear optical properties of many materials and devices have been the main object of research as potential candidates for sensing in different places. Just one of these properties has been, in most of the cases, the basis for the sensing operation. As a consequence, just one parameter can be detected. In this paper, although just one property will be employed too, we will show the possibility to sense different parameters with just one type of sensor. The way adopted in this work is the use of the optical bistability obtained from different photonic structures. Because this optical bistability has...
Bit noise from an optical logic gate with laser diodes - González Marcos, Ana; Martín Pereda, José Antonio; Hurtado Villavieja, Antonio
Output bits from an optical logic cell present noise due to the type of technique used to obtain the Boolean functions of two input data bits. We have simulated the behavior of an optically programmable logic cell working with Fabry Perot-laser diodes of the same type employed in optical communications (1550nm) but working here as amplifiers. We will report in this paper a study of the bit noise generated from the optical non-linearity process allowing the Boolean function operation of two optical input data signals. Two types of optical logic cells will be analyzed. Firstly, a classical "on-off" behavior, with...
An alternative for reducing the layers in the construction of three-phase planar transformers - Prieto López, Roberto; Asensi Orosa, Rafael; García Suárez, Oscar; Cobos Márquez, José Antonio; Jerez, F.; Flavio David, Gerez
A modified winding layout for three-phase transformers with PCB windings is proposed in this paper. This modified layout can be used in high current transformers with many PCB layers to simplify the fabrication process. One of the key factors that might increase the cost and complexity in the construction of planar transformers is the number of layers of each PCB winding. This issue becomes even more important in medium-high power three-phase transformers, where the number of PCB layers is higher. In addition to that, the proposed method allows the use of commercial core shapes that are commonly used to design...
An overview of fast DC-DC converters for envelope amplifier in RF transmitters - García Suárez, Oscar; Vasic, Miroslav; Alou Cervera, Pedro; Oliver Ramírez, Jesús Angel; Cobos Márquez, José Antonio
In the last years, RF power amplifiers are taking advantage of the switched dc-dc converters to use them in several architectures that may improve the efficiency of the amplifier, keeping a good linearity. The use of linearization techniques such as Envelope Elimination and Restoration (EER) and Envelope Tracking (ET) requires a very fast dc-dc power converter to provide variable voltage supply to the power amplifier but theoretically the efficiency can be much higher than using the classical amplifiers belonging to classes A, B or AB. The purpose of this paper is to analyze the state of the art of the...
Analysis and optimized design of a distributed multi-stage EMC filter for an interleaved three-phase PWM-rectifier system for aircraft applications - Hensgens, Nico H.; Silva Fernández, Marcelo Alexis; Oliver Ramírez, Jesús Angel; Alou Cervera, Pedro; García Suárez, Oscar; Cobos Márquez, José Antonio
Different possible input filter configurations for a modular three-phase PWM rectifier system consisting of three interleaved converter cells are studied. The system is designed for an aircraft application where MIL-STD-461E conducted EMI standards have to be met and system weight is a critical design issue. The importance of a LISN model on the simulated noise levels and the effect of interleaving and power unbalance between the different converter modules is discussed. The effect of the number of filter stages and the degree of distribution of the filter stages among the individual converter modules on the weight and losses of the...
Automatized connection of the layers of planar transformers with parallel windings to improve the component behavior - Asensi Orosa, Rafael; Prieto López, Roberto; Cobos Márquez, José Antonio
Transformers with parallel windings are commonly used to reduce the losses in the windings. Windings losses depend on the winding positioning and the frequency effects because each winding affects the current sharing of itself and the neighboring windings. In this paper a methodology for determining the connections of the parallel windings that reduces the power losses (and temperature) in the windings of multi-winding transformers is presented. Other applications of the method, such as balanced current sharing and voltage drop reduction are also explored. In this paper a methodology for determining the connections of the parallel windings that reduces the power...
Comparison of V2IC control with voltage mode and current mode controls for high frequency (MHz) and very fast response applications - Alou Cervera, Pedro; Oliver Ramírez, Jesús Angel; Svikovic, Vladimir; García Suárez, Oscar; Cobos Márquez, José Antonio
High switching frequencies (several MHz) allow the integration of low power DC/DC converters. Although, in theory, a high switching frequency would make possible to implement a conventional Voltage Mode control (VMC) or Peak Current Mode control (PCMC) with very high bandwidth, in practice, parasitic effects and robustness limits the applicability of these control techniques. This paper compares VMC and CMC techniques with the V2IC control. This control is based on two loops. The fast internal loop has information of the output capacitor current and the error voltage, providing fast dynamic response under load and voltage reference steps, while the slow...
Optimal design of AC EMI filters with damping networks and effect on the systems power factor - Hensgens, Nico H.; Silva Fernández, Marcelo Alexis; Oliver Ramírez, Jesús Angel; Cobos Márquez, José Antonio; Skibin, Stanislav; Ecklebe, Andreas
The cutoff frequencies of an EMI filter are normally given by the noise attenuation requirements the filter has to fulfill. In order to select the component values of the filter elements, i.e. inductances and capacitances, an additional design criterium is needed. In this paper the effect of the EMI filter input and output impedances are considered. The input impedance influences the filters effect on the system displacement power factor and the output impedance plays a key role in the system stability. The effect of filter element values, the number of filter stages as well as additional damping networks are considered...
Nanocrack-induced leakage current in AlInN/AlN/GaN - Minj, Albert; Cavalcoli, Daniela; Pandey, Saurabh; Fraboni, Beatrice; Cavallini, Anna; Brazzini, Tommaso; Calle Gómez, Fernando
Here we report on the study of nano-crack formation in Al1−xInxN/AlN/GaN heterostructures, on its association with composition fluctuation and on its local electrical properties. It is shown here that indium segregation at nano-cracks and threading dislocations originating from the non-pseudomorphic AlN interlayer could be the cause of the high reverse-bias gate leakage current of Ni/Au Schottky contacts on Al1−xInxN/AlN/GaN heterostructures and significantly affects the contact rectifying behavior. Segregation of indium around crack tips in Al1−xInxN acting as conductive paths was assessed with conductive atomic force microscopy.
Wireless measurement system for structural health monitoring with high time synchronization accuracy - Araujo Pinto, Álvaro; García Palacios, Jaime; Blesa Martínez, Javier; Tirado, Francisco; Romero Perales, Elena; Samartin Quiroga, Avelino F.; Nieto-Taladriz García, Octavio
Structural health monitoring (SHM) systems have excellent potential to improve the regular operation and maintenance of structures. Wireless networks (WNs) have been used to avoid the high cost of traditional generic wired systems. The most important limitation of SHM wireless systems is time-synchronization accuracy, scalability, and reliability. A complete wireless system for structural identification under environmental load is designed, implemented, deployed, and tested on three different real bridges. Our contribution ranges from the hardware to the graphical front end. System goal is to avoid the main limitations of WNs for SHM particularly in regard to reliability, scalability, and synchronization. We...
On the dynamic adaptation of language models based on dialogue information - Lucas Cuesta, Juan Manuel; Ferreiros López, Javier; Fernández Martínez, Fernando; Echeverry Correa, Julian David; Lebai Lutfi, Syaheerah Binti
We present an approach to adapt dynamically the language models (LMs) used by a speech recognizer that is part of a spoken dialogue system. We have developed a grammar generation strategy that automatically adapts the LMs using the semantic information that the user provides (represented as dialogue concepts), together with the information regarding the intentions of the speaker (inferred by the dialogue manager, and represented as dialogue goals). We carry out the adaptation as a linear interpolation between a background LM, and one or more of the LMs associated to the dialogue elements (concepts or goals) addressed by the user....
Sensorless explicit model predictive control for multi-phase buck converters with variable output voltage - Catalanotto, Giuseppe; García Suárez, Oscar; Oliver Ramírez, Jesús Angel; Alou Cervera, Pedro; Cobos Márquez, José Antonio
The purpose of this paper is to use the predictive control to take advantage of the future information in order to improve the reference tracking. The control attempts to increase the bandwidth of the conventional regulators by using the future information of the reference, which is supposed to be known in advance. A method for designing a controller is also proposed. A comparison in simulation with a conventional regulator is made controlling a four-phase Buck converter. Advantages and disadvantages are analyzed based on simulation results.
Survey of architectures and optimizations for wide bandwidth envelope amplifier - Vasic, Miroslav; García Suárez, Oscar; Oliver Ramírez, Jesús Angel; Alou Cervera, Pedro; Cobos Márquez, José Antonio
In the last years, RF power amplifiers are taking
advantage of the switched dc-dc converters to use them in
several architectures that may improve the efficiency of the
amplifier, keeping a good linearity. The use of linearization techniques such as Envelope Elimination and Restoration(EER) and Envelope Tracking (ET) requires a very fast dc-dc power converter to provide variable voltage supply to the power amplifier but theoretically the efficiency can be much higher than using the classical amplifiers belonging to classes A, B or AB. The purpose of this paper is to analyze the state of the art of the power...
The DLMT hardware implementation. A comparative study with the DCT and the DWT - Moreno González, Felix Antonio; Aledo Ortega, David
In the last recent years, with the popularity of image compression techniques, many architectures have been proposed. Those have been generally based on the Forward and Inverse Discrete Cosine Transform (FDCT, IDCT). Alternatively, compression schemes based on discrete "wavelets" transform (DWT), used, both, in JPEG2000 coding standard and in H264-SVC (Scalable Video Coding) standard, do not need to divide the image into non-overlapping blocks or macroblocks. This paper discusses the DLMT (Discrete Lopez-Moreno Transform) hardware implementation. It proposes a new scheme intermediate between the DCT and the DWT, comparing results of the most relevant proposed architectures for benchmarking. The DLMT...
Diseño del equipamiento de un estudio de grabación digital - Herreros Carballo, Sergio
El presente proyecto describe la instalación de audio de un estudio de grabación digital musical. La finalidad de este proyecto es puramente educativa, afianzando conceptos que se han contemplado durante la carrera. La instalación tiene
carácter ficticio, por lo que no tiene implementación real. Aun así, se ha intentado desarrollar con carácter profesional.
El proyecto se ha dividido en varias fases de trabajo. Primeramente, se procedió a la búsqueda de información relativa a estudios de grabación, atendiendo principalmente a sus configuraciones. Paralelamente, se buscó información sobre los principales equipos dentro de un estudio de grabación y realizando un pequeño estudio de mercado.
Mobile devices: dominant design as a goal - Alija Fuertes, Miguel Jesús
Since the beginning of the smartphones in the 80s, the mobile device market has grown and evolved towards devices connected everywhere, with hardware more and more close to
computers and laptops than a classic mobile telephone. Nowadays, this market seems to be crowded and some companies seem not to know exactly which step is next. In this manner, a concept appears in the market as a solution or a difficulty to overcome: the dominant design. The thesis aims to establish an analysis and definition of what a dominant design is and how we should understand this concept: which are the costumers’...
Study of the effect of different hole sizes on mechanical strength of wafers for back contact solar cells - Cereceda, Eneko; Barredo Egusquiza, Josu; Gutiérrez, J.R.; Jimeno, Juan Carlos; Fraile de Lerma, Alberto; Hermanns, Lutz Karl Heinz
Drilling process on wafers to produce EWT or MWT solar cells is a critical fabrication step, which affects on their mechanical stability. The amount of damage introduced during drilling process depends on the density of holes, their size and the chemical process applied afterwards. To quantify the relation between size of the holes and reduction of mechanical strength, several sets of wafers have been prepared, with different hole diameter. The mechanical strength of these sets has been measured by the ring on ring bending test, and the stress state in the moment of failure has been deduced by FE simulation.
Aplicación de nuevas tecnologías en los sistemas de alumbrado - Mahtani Bhagwandas, Navin
A medida que transcurre el tiempo la sociedad evoluciona, las ciudades crecen, se modernizan, mejoran su infraestructura y se ofrecen más y mejores servicios a sus
ciudadanos. Esto ha hecho que durante muchos años las ciudades se hayan desarrollado sin pensar en lo que vendrá más adelante, contaminando el medio ambiente y consumiendo mucha energía y de forma ineficiente. Ante esta situación, y gracias a las innovaciones tecnológicas en materia de comunicaciones, se están adoptando medidas para dirigir la evolución de las ciudades hacia un modelo de ciudad inteligente y sostenible.
Las redes de comunicaciones constituyen uno de los pilares sobre los...