Performance Analysis of Non-Ideal MIMO Systems in Fading Channels

En esta tesis se aborda el análisis de prestaciones de sistemas MIMO bajo ciertas condiciones no ideales. Se han considerado limitaciones realistas como son las interferencias co-canal, el canal de retorno con velocidad limitada, y la correlación espacial entre antenas. Bajo estas condiciones, se han analizado las probabilidades de error y de outage para sistemas MIMO que incluyen técnicas de conformación de haz en el transmisor y/o distintas técnicas de diversidad espacial en el receptor. Con el fin de obtener expresiones cerradas y exactas par los indicadores de rendimiento mencionados, se han desarrollo nuevos métodos o herramientas matemáticas que facilitan o, en algunos casos, hacen posible el análisis. En primer lugar, se han obtenido nuevas expresiones cerradas para las integrales del tipo Lipschitz-Hankel y para la distribución de los elementos de la diagonal de matrices Wishart complejas. Posteriormente, estos resultados han sido aplicados al análisis de prestaciones de distintos sistemas MIMO en condiciones no-ideales. Concretamente, se han obtenido nuevas expresiones cerrradas de la probabilidad de outage para: sistemas MRC con interferencia co-canal, sistemas MIMO con correlación espacial entre antenas, y sistemas MIMO MRC con un canal de retorno limitado en velocidad. Además, se han obtenido expresiones cerradas para la probabilidad de error en sistemas de diversidad en recepción que emplean modulaciones no coherentes y no ortogonales

A Unification of LoS, Non-LoS and Quasi-LoS Signal Propagation in Wireless Channels

The modeling of wireless communications channels is often broken down into two distinct states, defined according to the optical viewpoints of the transmitter (TX) and receiver (RX) antennas, namely line-of-sight (LoS) and non-LoS (NLoS). Movement by the TX, RX, both and/or objects in the surrounding environment means that channel conditions may transition between LoS and NLoS leading to a third state of signal propagation, namely quasi-LoS (QLoS). Unfortunately, this state is largely ignored in the analysis of signal propagation in wireless channels. We therefore propose a new statistical framework that unifies signal propagation for LoS, NLoS, and QLoS channel conditions, leading to the creation of the Three State Model (TSM). The TSM has a strong physical motivation, whereby the signal propagation mechanisms underlying each state are considered to be similar to those responsible for Rician fading. However, in the TSM, the dominant signal component, if present, can be subject to shadowing. To support the use of the TSM, we develop novel formulations for the probability density functions of the in-phase and quadrature components of the complex received signal, the received signal envelope, and the received signal phase. Additionally, we derive an expression for the complex autocorrelation function of the TSM, which will be of particular importance in understanding and simulating its time correlation properties. Finally, we show that the TSM provides a good fit to field measurements obtained for two different bodycentric wireless channels operating at 2.45 GHz, which are known to be subject to the phenomena underlying the TSM.The State Research Agency (AEI) of SpainThe European Social Fund under grant RYC2020-030536-IAEI under grant PID2020-118139RB-I00

Variable-selection ANOVA Simultaneous Component Analysis (VASCA)

Motivation: ANOVA Simultaneous Component Analysis (ASCA) is a popular method for the analysis of multivariate data yielded by designed experiments. Meaningful associations between factors/interactions of the experimental design and measured variables in the dataset are typically identified via significance testing, with permutation tests being the standard go-to choice. However, in settings with large numbers of variables, like omics (genomics, transcriptomics, proteomics and metabolomics) experiments, the ‘holistic’ testing approach of ASCA (all variables considered) often overlooks statistically significant effects encoded by only a few variables (biomarkers). Results: We hereby propose Variable-selection ASCA (VASCA), a method that generalizes ASCA through variable selection, augmenting its statistical power without inflating the Type-I error risk. The method is evaluated with simulations and with a real dataset from a multi-omic clinical experiment. We show that VASCA is more powerful than both ASCA and the widely adopted false discovery rate controlling procedure; the latter is used as a benchmark for variable selection based on multiple significance testing. We further illustrate the usefulness of VASCA for exploratory data analysis in comparison to the popular partial least squares discriminant analysis method and its sparse counterpart.Agencia Andaluza del Conocimiento, Regional Government of Andalucia , in SpainEuropean Commission B-TIC-136-UGR20State Research Agency (AEI) of SpainEuropean Social Fund (ESF) RYC2020-030536-IAEI PID2020-118139RB-I0

Use of Carbonated Water as Kneading in Mortars Made with Recycled Aggregates

The increased concern about climate change is revolutionising the building materials sector, making sustainability and environmental friendliness increasingly important. This study evaluates the feasibility of incorporating recycled masonry aggregate (construction and demolition waste) in porous cement-based materials using carbonated water in mixing followed (or not) by curing in a CO2 atmosphere. The use of carbonated water can be very revolutionary in cement-based materials, as it allows hydration and carbonation to occur simultaneously. Calcite and portlandite in the recycled masonry aggregate and act as a buffer for the low-pH carbonated water. Carbonated water produced better mechanical properties and increased accessible water porosity and dry bulk density. The same behaviour was observed with natural aggregates. Carbonated water results in an interlaced shape of carbonate ettringite (needles) and fills the microcracks in the recycled masonry aggregate. Curing in CO2 together with the use of carbonated water (concomitantly) is not beneficial. This study provides innovative solutions for a circular economy in the construction sector using carbonated water in mixing (adsorbing CO2), which is very revolutionary as it allows carbonation to be applied to in-situ products

Review of the Application of Hydrotalcite as CO2 Sinks for Climate Change Mitigation

In recent decades, the environmental impact caused by greenhouse gases, especially CO2, has driven many countries to reduce the concentration of these gases. The study and development of new designs that maximise the efficiency of CO2 capture continue to be topical. This paper presents a review of the application of hydrotalcites as CO2 sinks. There are several parameters that can make hydrotalcites suitable for use as CO2 sinks. The first question is the use of calcined or uncalcined hydrotalcite as well as the temperature at which it is calcined, since the calcination conditions (temperature, rate and duration) are important parameters determining structure recovery. Other aspects were also analysed: (i) the influence of the pH of the synthesis; (ii) the molar ratio of its main elements; (iii) ways to increase the specific area of hydrotalcites; (iv) pressure, temperature, humidity and time in CO2 absorption; and (v) combined use of hydrotalcites and cement-based materials. A summary of the results obtained so far in terms of CO2 capture with the parameters described above is presented. This work can be used as a guide to address CO2 capture with hydrotalcites by showing where the information gaps are and where researchers should apply their efforts

Attosecond control of spin polarization in electron–ion recollision driven by intense tailored fields

Tunnel ionization of noble gas atoms driven by a strong circularly polarized laser field in combination with a counter-rotating second harmonic generates spin-polarized electrons correlated to the spin-polarized ionic core. Crucially, such two-color field can bring the spin-polarized electrons back to the parent ion, enabling the scattering of the spin-polarized electron on the spin-polarized parent ion. Here we show how one can control the degree of spin polarization as a function of electron energy and recollision time by tuning the laser parameters, such as the relative intensities of the counter-rotating fields. The attosecond precision of the control over the degree of spin polarization opens the door for attosecond control and spectroscopy of spin-resolved dynamics

Improvement project in a primary school in northwest Mexico

El presente estudio muestra la experiencia que se siguió para detectar un área de mejora en una institución de reciente creación de educación primaria del noroeste de México, perteneciente a una red de centros escolares en el país. La pregunta de investigación fue: ¿Cuál es el conocimiento y aplicación de un modelo educativo por parte de los docentes de un centro escolar de reciente creación en el noroeste de México? El objetivo del estudio fue conocer el nivel de apropiación que tienen los docentes de un centro escolar acerca de un modelo educativo, con la intención de indagar las implicaciones en las dimensiones de la gestión escolar, organizativa, pedagógica-curricular y de participación social. Se siguió una metodología cualitativa con un enfoque de estudio de casos donde se consultó a docentes, padres de familia y director del centro escolar donde se realizó el estudio. Los resultados permitieron detectar nuevas áreas de mejora en la réplica del modelo educativo, dado que la institución tiene la responsabilidad de asegurar la calidad de los egresados, la institucionalización del modelo educativo, la continuidad del sistema y la apertura de los nuevos centros escolaresThis paper presents the experience to perceive an area of improvement in a newly created institution of elementary education in northwestern Mexico, which belongs to a network of schools in the country. The research question was: What is the level of knowledge and application of an educational model based on values by the teachers of a newly established school in northwestern Mexico? The aim of the study was to determine the level of ownership that teachers have on an educational model, with the purpose to determine the implications on the organizational, pedagogical-curricular and social participation of the school management dimensions. A qualitative methodology was followed based on a case study approach where teachers, parents and director of the school were interviewed. Results allowed to define new areas of improvement in the educational model mimic, because the institution has the responsibility to ensure the quality of graduates, the institutionalization of the educational model, the continuity of the system and opening new school

A Novel Artificial Neural Network to Predict Compressive Strength of Recycled Aggregate Concrete

Most regulations only allow the use of the coarse fraction of recycled concrete aggregate (RCA) for the manufacture of new concrete, although the heterogeneity of RCA makes it difficult to predict the compressive strength of concrete, which is an obstacle to the incorporation of RCA in concrete production. The compressive strength of recycled aggregate concrete is closely related to the dosage of its constituents. This article proposes a novel artificial neural network (ANN) model to predict the 28-day compressive strength of recycled aggregate concrete. The ANN used in this work has 11 neurons in the input layer: the mass of cement, fly ash, water, superplasticizer, fine natural aggregate, coarse natural or recycled aggregate, and their properties, such as: sand fineness modulus of sand, water absorption capacity, saturated surface dry density of the coarse aggregate mix and the maximum particle size. Two training methods were used for the ANN combining 15 and 20 hidden layers: Levenberg–Marquardt (LM) and Bayesian Regularization (BR). A database with 177 mixes selected from 15 studies incorporating RCA were selected, with the aim of having an underlying set of data heterogeneous enough to demonstrate the efficiency of the proposed approach, even when data are heterogeneous and noisy, which is the main finding of this work

Sistema de consulta de notas a través de Páginas Web y de Telefonía Móvil

In this paper we are going to present a system which lets any student at Cordoba University knows what the final qualifications he has obtained in the different subjects he is registered are. The sytem lets him consult the qualifications using Internet and mobile telephony. Teachers who are reagistered in the system can upload tha qualifications without addtional software, they only need the certificate file generated by the UcoActas application. Then, all the registered students in this subject and in this service, will receive an e-mail to notify them that they can consult the qualifications. Then, they can use a Web browser or they can use a specific mobile application to consult them. Currently we are doing functionality tests with voluntary students from different courses.En este artículo se presenta un sistema que permite a cualquier alumno de la Universidad de Córdoba informarse sobre las calificaciones finales obtenidas en las asignaturas en las que está matriculado. El sistema permite consultar las notas de las actas utilizando Internet y Telefonía Móvil. Los profesores que estén dados de alta en el sistema podrán subir las notas sin necesidad de utilizar un tercer "software", directamente con el fichero de las actas generado por el programa UcoActas. Una vez subidas las notas, todos los alumnos matriculados que estén suscritos a este servicio, recibirán un e-mail con el aviso de que la consulta en la Web está disponible. Si el alumno lo desea, también podrá consultar sus notas publicadas utilizando un programa para dispositivos móviles que hará una petición segura al sistema. Actualmente se están realizando pruebas de actualización con estudiantes voluntarios de varias asignaturas

Efectos de una unidad didáctica ludotécnica en el aprendizaje del salto de altura de alumnos de bachillerato

The aim of this study was to verify the influence of ludotechnic model to teach the high jump discipline in the Secondary Education Physical Education context. The study sought to test students’ satisfaction, their learning of the technique and their performance. The teaching unit intervention consisted of 6 sessions with 24 high school students, 11 male and 13 female. Following a quasi-experimental intervention, a pretest and postest previously validated were used to assess the satisfaction-boredom (8 items), and a protocol for performance measurement (12 premises) and the height (all sessions were videotaped and analysed afterwards). The results indicated significant differences: increase of students satisfaction t (,0039) <0,05 (M= 3,37 to 3,76), decrease of students boredom t (,0010) <0,05 (M= 2,6 to 2,03), and improvement of technical execution (3,8 to 7,4 was achieved in 12 items available. p<0,05). The conclusion is that the ludtechnic model is a method that enables the development of a more motivating, satisfying and efficient (improvement of the sport discipline objectives) physical education lessons.El objetivo del presente estudio fue comprobar la influencia del modelo ludotécnico para enseñar la disciplina del salto de altura en el contexto de clase de educación física. El estudio se centró en la satisfacción de los estudiantes, su aprendizaje de la técnica y su eficacia en la realización de esta prueba. Se llevó a cabo una intervención de 6 sesiones con 24 alumnos de 2º de Bachillerato, 11 hombres y 13 mujeres. Se sometió a los participantes a una intervención cuasi-experimental compuesta por un pre-test y un post-test mediante un cuestionario validado, para evaluar la satisfacción-aburrimiento (8 ítems), y un protocolo de salto para medir la ejecución técnica (12 premisas) y la altura alcanzada, mediante grabaciones en las seis sesiones llevadas a cabo. Los resultados indicaron que aumentó de forma significativa la satisfacción t (0,039) < 0,05 (M= 3,37 a 3,76), disminuyó el aburrimiento t (0,010) < 0,05 (M= 2,60 a 2,03), y se logró una mejor ejecución técnica p < 0,05 (M= 3,8 a 7,4, sobre 12). Como conclusión, podemos indicar que el modelo ludotécnico es una metodología que posibilita un desarrollo más motivante, satisfactorio y eficaz (logro los objetivos técnicos de la disciplina deportiva) de las clases de educación física