Search results for "comunicaciones"
showing 10 items of 175 documents
High-Power Multicarrier Generation for RF Breakdown Testing
2017
Testing of satellite components for high RF power breakdown effects, such as multipactor and corona or passive-intermodulation, is a topic of growing interest in the aerospaceindustry. Switching fromthe classical single carrier approach to the more realisticmulticarrier scenario is very challenging from the experimental point of view. Themulticarrier signals, amplifiedby several RF power amplifiers, need to have controlled phase, amplitude, and frequency in each carrier. Fine tuning of the signal generator phases is required in order to compensate the phase drift occurring in the active elements of the test bed. This paper presents an efficient and low-cost technique to generate multicarrie…
Study of the Secondary Electron Yield in Dielectrics Using Equivalent Circuital Models
2018
[EN] Secondary electron emission has an important role on the triggering of the multipactor effect; therefore, its study and characterization are essential in radio-frequency waveguide applications. In this paper, we propose a theoretical model, based on equivalent circuit models, to properly understand charging and discharging processes that occur in dielectric samples under electron irradiation for secondary electron emission characterization. Experimental results obtained for Pt, Si, GaS, and Teflon samples are presented to verify the accuracy of the proposed model. Good agreement between theory and experiments has been found.
ZnMgO-based UV photodiodes: a comparison of films grown by spray pyrolysis and MBE
2016
Detecting the UV part of the spectrum is fundamental for a wide range of applications where ZnMgO has the potential to play a central role. The shortest achievable wavelength is a function of the Mg content in the films, which in turn is dependent on the growth technique. Moreover, increasing Mg contents lead to an electrical compensation of the films, which directly affects the responsivity of the photodetectors. In addition, the metal-semiconductor interface and the presence of grain boundaries have a direct impact on the responsivity through different gain mechanisms. In this work, we review the development of ZnMgO UV Schottky photodiodes using molecular beam epitaxy and spray pyrolysis…
Optical properties and microstructure of 2.02-3.30 eV ZnCdO nanowires: effect of thermal annealing
2013
International audience; ZnCdO nanowires with up to 45% Cd are demonstrated showing room temperature photoluminescence (PL) down to 2.02 eV and a radiative efficiency similar to that of ZnO nanowires. Analysis of the microstructure in individual nanowires confirms the presence of a single wurtzite phase even at the highest Cd contents, with a homogeneous distribution of Cd both in the longitudinal and transverse directions. Thermal annealing at 550 C yields an overall improvement of the PL, which is blue-shifted as a result of the homogeneous decrease of Cd throughout the nanowire, but the single wurtzite structure is fully maintained.
Impact of texture TDS and flavour TDS tasks and of chocolate-chip biscuit characteristics on oral processing features
2019
The objective of the present study was to investigate differences in oral activity when biscuits of the same type but with subtle composition differences are consumed and how performing a Temporal Dominance of Sensations (TDS) task modifies the way one eats. In addition, comparisons were made between performing a texture TDS (T-TDS) and a flavour TDS (F-TDS). Oral activity while eating biscuits with and without conducting a TDS task was recorded using a 3.dimensional motion capture system to monitor the evolution of jaw movements. The results showed that oral activity evolved over the consumption time, differed depending on the texture of the sample and was affected to a small but significa…
Validation of Using Smartphone Built-In Accelerometers to Estimate the Active Energy Expenditures of Full-Time Manual Wheelchair Users with Spinal Co…
2021
[EN] This study aimed to investigate the validity of using built-in smartphone accelerometers to estimate the active energy expenditures of full-time manual wheelchair users with spinal cord injury (SCI). Twenty participants with complete SCI completed 10 5-min daily activities that involved the upper limbs, during which their oxygen consumption and upper limb activity were registered using a portable gas analyzer and a smartphone (placed on the non-dominant arm), respectively. Time series of 1-min averaged oxygen consumption and 55 accelerometer variables (13 variables for each of the four axes and three additional variables for the correlations between axes) were used to estimate three mu…
La adopción abierta en el derecho español
2016
El reconocimiento del derecho del menor adoptado a mantener contactos o relaciones con sus familiares de origen y sus anteriores acogedores representa un nuevo modelo de adopción en el Derecho español, denominado “adopción abierta”, recientemente introducida por la Ley 26/2015, de 28 de julio, que reforma el sistema español de protección de la infancia y la adolescencia. La nueva regulación se inspira en el Derecho de otros países pero tiene precedentes en ciertas normas autonómicas españolas The recognition of the right of the adopted children to maintain contacts or relations with their families of origin and previous welcoming, represents a new model of adoption in the Spanish law, which…
Uso de Software-Defined Radio en la enseñanza de sistemas de comunicaciones
2017
[ES] En la docencia de sistemas de comunicación hay una componente teórica elevada. La percepción de los estudiantes al estudiar estas asignaturas es negativa. Este trabajo trata de explicar la motivación y la estrategia seguida para reorientar esta percepción a partir de la introducción de elementos de “Software-Defined Radio” (SDR) y “Universal Software Radio Peripherals” (USRP) en diferentes asignaturas del Grado de Ingenier´ıa Telem´atica de la Universitat de València
Conversión de formatos de proyección y codificación basada en campo de visión para streaming adaptativo de videos 360º utilizando DASH
2019
En este trabajo final de grado se ha extendido una plataforma extremo-a-extremo para la preparación, distribución y reproducción de vídeos 360º con tal de poder adoptar proyecciones CMP homogéneas, existentes hasta la fecha, además de otras configuraciones más avanzadas que permiten concentrar la resolución en áreas concretas del video 360º. In this final degree project, an end-to-end platform has been extended for the preparation, distribution and playback of 360º videos in order to be able to adopt homogeneous CMP projections, existing to date, in addition to other more advanced configurations that allow concentrating the resolution in specific areas of the 360º video.
Validity, reliability, and sensitivity to motor impairment severity of a multi-touch app designed to assess hand mobility, coordination, and function…
2021
[EN] Background: The assessment of upper-limb motor impairments after stroke is usually performed using clinical scales and tests, which may lack accuracy and specificity and be biased. Although some instruments exist that are capable of evaluating hand functions and grasping during functional tasks, hand mobility and dexterity are generally either not specifically considered during clinical assessments or these examinations lack accuracy. This study aimed to determine the convergent validity, reliability, and sensitivity to impairment severity after a stroke of a dedicated, multi-touch app, named the Hand Assessment Test. Methods: The hand mobility, coordination, and function of 88 individ…