Generalized MGF of Beckmann Fading with Applications to Wireless Communications Performance Analysis

The Beckmann distribution is a general multipath fading model for the received radio signal in the presence of a large number of scatterers, which can thence be modeled as a complex Gaussian random variable where both the in-phase and quadrature components have arbitrary mean and variance. However, the complicated nature of this distribution has prevented its widespread use and relatively few analytical results have been reported for this otherwise useful fading model. In this paper, we derive a closed-form expression for the generalized moment-generating function (MGF) of the signal-to-noise ratio (SNR) of Beckmann fading, which permits to circumvent the inherent analytical complexity of this model. This is a new and useful result, as it is key for evaluating several important performance metrics of different wireless communication systems and also permits to readily compute the moments of the output SNR. Thus, we obtain simple exact expressions for the energy detection performance in Beckmann fading channels, both in terms of the receiver operating characteristic (ROC) curve and of the area under ROC curve. We also analyze the outage probability in interference limited systems affected by Beckmann fading, as well as the outage probability of secrecy capacity in wiretap Beckmann fading channels. Monte Carlo simulations have been performed to validate the derived expressions.Universidad de Málaga. Campus de Excelencia Internacional. Andalucía Tech

Using one-dimensional modeling to analyse the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Detailed injection system model

A combined experimental and computational investigation has been performed in order to evaluate the influence of physical properties of biodiesel on the injection process in a common-direct injection system with second generation solenoid injectors. For that purpose, after a complete characterization of the system, which involved mechanical and hydraulic characterization, a one-dimensional model has been obtained and extensively validated. Simulations have then been performed with a standard diesel and a 100% rape methyl ester (RME) biodiesel which allowed a comparison and analysis of the dynamic response of the injector to be done. Different injection strategies involving main injection and main plus post-injection have been used to explore the impact of the use of biodiesel on the performance and stability of solenoid injectors. As far as the dynamic response of the injector is concerned, the results obtained have clearly shown that the use of biodiesel affects the dynamic response of the needle, especially at low injection pressures. The behavior of the system under multi-injection strategies (main plus post-injection) has been also evaluated determining for different operating conditions (injection pressures and backpressures) the minimum dwell time between injections to assure a stable behavior in the injection process (mass flow rate). Important differences have been found between biodiesel and standard diesel in this critical parameter at low injection pressures, becoming less important at high injection pressure. Finally, a modification on the injector hardware has been proposed in order to compensate these differences.This research has been funded by "Ministerio de Ciencia e Innovacion" in the frame of the project "Estudio teorico experimental de la influencia del combustible sobre la cavitacion y el desarrollo del chorro evaporative (FlexiFuel)", Reference TRA2010-17564.Payri Marín, R.; Salvador Rubio, FJ.; Marti Aldaravi, P.; Martínez López, J. (2012). Using one-dimensional modeling to analyse the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Detailed injection system model. Energy Conversion and Management. 54(1):90-99. https://doi.org/10.1016/j.enconman.2011.10.004S909954

Sistema embebido para el control de carga de baterías en un vehículo eléctrico híbrido ligero (EPISOL)

El presente trabajo es resultado de un proyecto para desarrollar un vehículo híbrido con varias fuentes de carga de baterías. Su objetivo es contribuir a reducir las emisiones debidas al tráfico urbano de vehículos, tendencia muy buscada en los últimos años, donde se han acometido importantes proyectos de investigación orientados al desarrollo de sistemas de propulsión y combustibles alternativos a los actualmente mayoritarios. A continuación se describe el sistema embebido de control realizado, en el que un microcontrolador se encarga del ajuste de la carga de las baterías, a partir de las contribuciones de una pila de combustible, unos paneles solares y un generador conectado a un motor de combustión interna, para conseguir el mayor rendimiento energético y lograr unos niveles de emisiones casi nulos

Definición de la gestión energética de un vehículo híbrido basada en la simulación del funcionamiento de los componentes del sistema propulsor en las condiciones de operación de diseño

La tendencia actual hacia el incremento de la movilidad en las sociedades más avanzadas va en contradicción con criterios de control de la contaminación local y la explotación de los recursos de combustible. Entre las soluciones planteadas, se encuentran los vehículos híbridos. En este artículo se presenta la definición y simulación de la gestión energética de uno de estos vehículos, a partir de las condiciones de operación. El vehículo híbrido diseñado en su totalidad combina propulsión con un motor eléctrico alimentado por baterías y un motor térmico, incluyéndose, además, paneles solares, así como carga externa por red eléctrica. Se han desarrollado modelos de simulación de los componentes y su integración. Analizando el campo de aplicación del vehículo, se ha planteado un ciclo de conducción a partir de ciclos estándar. Con el modelo, se ha analizado la idoneidad de diferentes estrategias de control de la energía, considerando diversas condiciones operativas

Characteristics of the Videos in Spanish Posted on Youtube about Human Papillomavirus Vaccines

Fundamentos: Internet constituye un recurso de búsqueda de información relacionada con la salud. El objetivo de este trabajo fue conocer las características de los vídeos en idioma español de YouTube relacionados con la vacuna contra el virus del papiloma humano (VPH). Métodos: Se realizó un estudio observacional a partir de una búsqueda en YouTube el 26 de julio de 2013, con las palabras claves: “vacuna virus papiloma humano”, “vacuna VPH”, “vacuna Gardasil”, “vacuna Cervarix”. Se establecieron categorías por tipo, fuente de publicación y predisposición favorable o no hacia la vacuna. Se registró el número de visitas, tiempo de duración de los videos y origen de los 20 vídeos más visitados. Resultados. Se encontraron 1.080 videos registrados, 170 fueron seleccionados y clasificados como: noticias locales (n=39; 37 favorables, 2 desfavorables; 2:06:29; 42972 visitas), noticias nacionales (n=32; 30/2; 1:49:27; 50138 visitas), creados por subscritores de YouTube (n=21; 13/8; 2:50:35; 144655 visitas), entrevistas (n=21; 20/1; 1:44:39; 10991 visitas), anuncios (n=21; 19/2; 0:27:05; 28435 visitas), conferencias (n=17; 15/2; 3:25:39; 27206 visitas), documentales (n=16; 12/4; 2:11:31; 30629 visitas), y noticias internacionales (n=3; 3/0; 0:11:33; 1667 visitas). De los 20 videos más reproducidos predominan los favorables a la vacunación (n=12; 0:43:43; 161.789 visitas) frente a los desfavorables (n=8; 2:44:14; 86.583 visitas). Conclusiones. Predominan los videos que tiene una opinión favorable hacia la vacuna contra el VPH, aunque los videos de contenido negativo son los más extensos y reproducidos.Background. Internet is a resource to search for health-related information. The aim of this work was to know the content of the videos in Spanish language of YouTube related to the vaccine against the human papilloma virus (HPV). Metthods. An observational study was conducted from a search on YouTube on 26th July 2013 by using keywords such as: “human papilloma virus vaccine”, “HPV vaccine”, “Gardasil vaccine”, “Cervarix vaccine”. Different categories were established according to: the type of vaccine, the published source and the favorable or unfavorable predisposition towards the human papillomavirus vaccination. The number of visits and the duration of the videos were gathered, with analysis of variables in the 20 most visited videos. Results. A total of 170 videos were classified like: local news (n=39; 37 favorable, 2 unfavorable; 2:06:29; 42972 visits), national news (n=32; 30/2; 1:49:27; 50138 visits), created by YouTube subscribers (n=21; 21/1; 1:44:39; 10991 visits), advertisements (n=21; 19/2; 0:27:05; 28435 visits), conferences (n=17; 15/2; 3:25:39; 27206 visits), documentaries (n=16; 12/4; 2:11:31; 30629 visits). From all of the 20 most viewed YouTube videos predominated those which were favorable to the vaccination (n=12; 0:43:43; 161789 visits) against the unfavorable (n=8; 2:44:14; 86583 visits). Conclusions. Most of the videos have a favorable opinion towards HPV vaccine, although videos with a negative content were the longest and most viewed

Numerical study of the behavior of an air pre-cooler

Introducing an air pre-cooler step before an air cooler system have been proved to improve the global efficiency of a cooling setup. Several authors have studied the mass and the heat exchanges of an air stream and the water sprayed inside an adiabatic cooling pad. However, these previous studies present their results and correlations as functions of experimental dependent parameters. Therefore, the aim of this study is to develop a numerical modeling capable of characterizing the behavior of an air pre-cooling stage without the need of previous experimental tests, allowing an accurate initial study when designing an air cooler installation. Several numerical models and simulation tests have been developed by our researching group in order to get a proper approximation of the problem, and the employment of previous experimental data allowed the model validation in terms of pressure drop and air cooling efficiency. As a result, a numerical model is defined, validated, and compared with existing empirical correlations models as a first step to determine the best possible cooling pad configuration in every air cooling setup as a function of the pad geometry, air and water flow rates, with an only numerical simulation.The authors acknowledge the financial support received from the Spanish Government, through Projects ENE2013-48696-C2-1-R and C2-2-R as well as by the FEDER (FondoEuropeo de Desarrollo Regional

Direct torque control of multiphase doubly converter-fed asynchronous machines incorporating the harmonic torques

Doubly fed asynchronous machines have an outstanding property: they can be operated up to twice rated speed delivering full rated torque. This paper presents, for the first time in the literature, a control system for multiphase asynchronous machines fed by Voltage Source Inverters (VSIs) both in stator and rotor that incorporates the harmonic torques. The system has three main and distinctive features: the independent control of the fundamental and harmonic torques, a very fast dynamic response for each one of these torques and a powerful method for selecting the best suited inverter state to achieve the evolution of the fundamental and harmonics flux linkage space phasors prescribed by the external control loops. The first feature is achieved through the decoupling of the multiphase machine provided by the Space Phasor Theory (SPhTh). The second one comes from the application of the General Approach for a very Fast TOrque Control (GAFTOC) principle. The third feature relies on using for multi-phase VSIs a simple but powerful switching-table based mode of operation that overcomes the limitations of the switching-table based modes of operation developed up to now, that only enable for the inverter to feed machines with no harmonic torques contribution

Functional brain networks reveal the existence of cognitive reserve and the interplay between network topology and dynamics

We investigated how the organization of functional brain networks was related to cognitive reserve (CR) during a memory task in healthy aging. We obtained the magnetoencephalographic functional networks of 20 elders with a high or low CR level to analyse the differences at network features. We reported a negative correlation between synchronization of the whole network and CR, and observed differences both at the node and at the network level in: the average shortest path and the network outreach. Individuals with high CR required functional networks with lower links to successfully carry out the memory task. These results may indicate that those individuals with low CR level exhibited a dual pattern of compensation and network impairment, since their functioning was more energetically costly to perform the task as the high CR group. Additionally, we evaluated how the dynamical properties of the different brain regions were correlated to the network parameters obtaining that entropy was positively correlated with the strength and clustering coefficient, while complexity behaved conversely. Consequently, highly connected nodes of the functional networks showed a more stochastic and less complex signal. We consider that network approach may be a relevant tool to better understand brain functioning in aging.Comment: Main manuscript: 23 pages including references, 20 pages text, 8 figures and supplementary information include

Commercial gilthead seabream (Sparus aurata L.) from the Mar Menor coastal lagoon as hotspots of microplastic accumulation in the digestive system

This paper presents the results on the presence and characterization of microplastics (MP) in the gastrointestinal tract of gilthead seabream (Sparus aurata L.), a species of commercial interest from the Mar Menor coastal lagoon in Southeast Spain. This is the first time that microplastic ingestion is recorded in any species from this semi-enclosed bay. Stomach and intestine from a total of 17 specimens captured by local fishermen were processed, and microplastic particles and fibers found in all of them were displayed. Overall, 40.32% (279/692) of total isolated microparticles proved to be microplastics; i.e., <5 mm, as identified by FTIR spectroscopy. The average value by fish was 20.11 _ 2.94 MP kg1, corresponding to average concentrations of 3912.06 _ 791.24 and 1562.17 _ 402.04 MP by kg stomach and intestine, respectively. Four MP forms were isolated: fiber (71.68%), fragment (21.15%), film (6.81%), and microbead (0.36%), with sizes ranging from 91 _m to 5 mm, an average of 0.83 _ 0.04 mm, and no statistically significant differences between mean sizes in stomach and intestine samples (F-test = 0.004; p = 0.936). Nine polymer types were detected, although most of fibers remained unidentified because of their small size, the presence of polymer additives, or closely adhered pollutants despite the oxidizing digestion carried out to eliminate organic matter. No significant correlation was found between main biological parameters and ingested microplastics, and high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene polypropylene (PEP), and polyvinyl (PV) were identified as the most abundant polymers. The average microplastic ingestion in this study area was higher than those reported in most studies within the Mediterranean Sea, and closely related to microplastic pollution in the surrounding area, although with a predominance of fiber form mainly due to fishery activities.This work was financed by Project 5345/18IQA (Technical University of Cartagena). Analyses carried out by Sonia Olmos were supported by a grant from Fundación Séneca (20268/FPI/17)

Estudio mediante CFD de la influencia de parámetros característicos en la eficiencia de la etapa de preenfriamiento en aerorefrigeradores

Los paneles de enfriamiento adiabático son ampliamente usados como paso previo a los sistemas de enfriamiento debido a que incrementan la eficiencia global de dicho sistema. El presente estudio está enfocado en el análisis, tanto numérico como experimental, de estos rellenos al variar su compacidad y su longitud. El principal objetivo de este trabajo es el desarrollo y la validación experimental de un modelo numérico de panel adiabático; para ello se han realizado numerosas simulaciones mediante el modelo de fase discreta (DPM) del software ANSYS Fluent. En estas simulaciones se puede observar la interacción entre las gotas de agua y la corriente de aire, siendo la segunda enfriada antes de su llegada al aero-refrigerador. Los resultados de este estudio muestran cómo afecta a la corriente de aire del problema, las variaciones de la compacidad del relleno y de su longitud.Los autores agradecen el apoyo financiero recibido por parte del Gobierno Español, a través del Proyecto ENE2013-48696-C2-1-R y C2-2-R, así como por el FEDER (Fondo Europeo de Desarrollo Regional)