El método de aproximación por media muestral

The sample average approximation (SAA) method is an approach for solving stochastic optimization problems by using Monte Carlo simulation. The basic idea of such method is that we can approximate the expected objetive function by the corresponding sample average function using a random sample. We solve the obtained sample average approximating problem by deterministic optimization techniques, and the process is repeated several times with different samples to obtain candidate solutions along with statistical estimates of their optimality gaps until a stopping criterion is satisfied. In section 1 we describe the expected value and sample average approximation problems and give a few examples of real cases in which it can be useful. In section 2 we show many results related to convergence of estimators (objective value, optimal solution, etc) under certain assumptions. In section 3 we discuss convergence rates of objetive values. In section 4 we implement the method to study two problems (that involve different random variables) to illustrate the power of the method.Universidad de Sevilla. Grado en Matemática

Relational analysis of the oil and gas sector of Mexico : Implications for Mexico's energy reform

Unidad de excelencia María de Maeztu MdM-2015-0552This paper describes a novel tool-kit to analyze energy systems in relation to the bio-economic and environmental performance of society. It is illustrated with data from the oil and gas sector of Mexico. The approach combines relational analysis (as developed in theoretical biology) and Multi-Scale Integrated Assessment of Societal and Ecosystem Metabolism (MuSIASEM). It integrates two non-equivalent views of the functioning of the oil and gas system starting from the identification and description of the relations between functional and structural elements. The metabolic pattern of the energy system is described as a sequential pathway generated by different functional elements (e.g., extraction, refining, transportation), each of which is made up of different structural elements (e.g., plants adopting different extraction techniques, diverse types of refineries, different methods of transportation), and operating at a given level of openness (imports and exports). The relations found over the elements of the energy system are described both in functional terms (what/why) and in spatial terms (where/how). The policy relevance of the information generated is discussed in relation to the Mexican Energy Reform

Quick Analysis of Organic Amendments via Portable X-ray Fluorescence Spectrometry

The determination of heavy metals in soils and organic amendments, such as compost, manure, biofertilizer, and sludge, generally involves the digestion of samples with aqua regia, and the determination of those in the solution using various techniques. Portable X-ray fluorescence (PXRF) has many advantages in relation to traditional analytical techniques. However, PXRF determines the total elemental content and, until now, its use for the analysis of organic amendments has been limited. The objective of this work is the calibration of a PXRF instrument to determine the aqua regia-soluble elemental contents directly in solid samples of organic amendments. Our proposal will avoid the digestion step and the use of other laboratory techniques. Using a training set of samples, calibration functions were obtained that allow the determination of the aqua regia-soluble contents from the PXRF readings of total contents. The calibration functions (obtained by multiple linear regression) allowed the quantitative determination of the aqua regia-soluble contents of Fe, K, P, S, Zn, Cu, Pb, Sr, Cr, and Mn, as well as the organic matter content and a semi-quantitative assessment of Al, Ca, V, Ba, Ni, and As contents. The readings of Si, Fe, Al, Ca, K, or S were used as correction factors, indicating that the calibrations functions found are truly based on the chemical composition of the sample matrix. This study will allow a fast, cheap, and reliable field analysis of organic amendments and of other biomass-based materials.Spanish Ministry of Science, Innovation and Universities, and the European Regional Development Fund, European Union, (AEI/FEDER, UE), grant number CGL2016-78937-R

Estrategia de intangibles en el medio televisivo

The new highly competitive TV ratings have positioned intangible values communication strategies at the very center of the TV channels’ marketing campaigns. Due to the homogeneity of the contents, it becomes necessary to add value to the television brands by means of managing intangible values so that they get a differentiated image. Broadcast companies, like any other, have decided to take care of their audiovisual aesthetics to capture their audience. Many of these companies are trying to stand out from their competence by offering to their audience new intangible values.La elevada competencia en el medio televisivo ha propiciado que las cadenas comiencen a establecer estrategias de comunicación donde los valores intangibles se han convertido en claros protagonistas. Ante una homogeneidad en la oferta de contenidos, se hace necesario agregar valor a las marcas televisivas por medio de la gestión de intangibles con el fin de desmarcarse y diferenciarse de su competencia. Las empresas audiovisuales, como cualquier otra empresa, han apostado por gestionar su comunicación y posicionar su marca a través de un cuidado en su estética audiovisual que genera una oportunidad para la captación de la audiencia. Muchas son ya las cadenas que intentan desmarcarse y diferenciarse de su competencia ofreciendo al espectador nuevos valores intangibles que se manifiestan por medio del diseño audiovisual. Estos nuevos valores se visualizan y expresan por medio del desarrollo de elementos, herramientas comunicativas y formas discursivas peculiares (sintonías, cortinillas de continuidad, cabeceras, grafismo, autopromociones, etc.), que sirven para posicionar y diferenciar unas cadenas de otras y, lo más importante, para definir y expresar una Identidad y una proyección de su Imagen Corporativa propia para crear ante el espectador un posicionamiento atractivo, diferenciador y positivo. Las características que posee el medio televisivo requieren un estudio sobre la manera en que las empresas audiovisuales gestionan estrategias basadas en valores intangibles con el objetivo de posicionarse ante una audiencia cada vez más exigente

Conjugated Polymers for Organic Electronics: Structural and Electronic Characteristics

The use of organic materials to design electronic devices has actually presented a broad interest for because they constitute an ecological and suitable resource for our current "electronic world". These materials provide several advantages (low cost, light weight, good flexibility and solubility to be easily printed) that cannot be afforded with silicium. They can also potentially interact with biological systems, something impossible with inorganic devices. Between these materials we can include small molecules, polymers, fullerenes, nanotubes, graphene, other carbon-based molecular structures and hybrid materials. Actually these materials are being used to build electronic structures into electronic devices, like organic light-emitting diodes (OLEDs), organic solar cells (OSCs), and organic field-effect transistors (OFETs), constituting and already commercial reality. Some of them are used on a widespread basis1, and are the focus of some recent researches in molecules2,3 and polymers4-6 suitable for these purposes. In this study we analyze the electronic and molecular characteristics of some different π-conjugated structures in order to evaluate their potential as semiconducting materials for organic electronics. For this purpose we focus on the study of conjugated polymers with different backbones configurations: (i) donor-acceptor configuration, (ii) 1D lineal or 2D branched conjugated backbones, and (iii) encapsulated polymers. To achieve this goal, we use a combined experimental and theoretical approach that includes electronic spectroscopies (i.e., absorption, emission and microsecond transient absorption), vibrational Raman spectroscopy and DFT calculations. These structural modifications are found to provoke a strong impact on the HOMO and LUMO levels and the molecular morphology, and, consequently, on their suitability as semiconductors in organic electronic applications.References 1. S. R. Forrest, M. E. Thompson. Chem. Rev., 2007, 107, 923 2. R. C. González-Cano, G. Saini, J. Jacob, J. T. López Navarrete, J. Casado and M. C. Ruiz Delgado. Chem. Eur. J. 2013, 19, 17165 3. J. L. Zafra, R. C. González-Cano, M. C. Ruiz Delgado, Z. Sun, Y. Li, J. T. López Navarrete, J. Wu and J. Casado. J. Chem. Phys. , 2014, 140, 054706 4. M. Goll, A. Ruff, E. Muks, F. Goerigk, B. Omiecienski, I. Ruff, R. C. González-Cano, J. T. López Navarrete, M. C. Ruiz Delgado, S. Ludwigs. Beilstein J. Org. Chem., 2015, 11, 335. 5. D. Herrero-Carvajal, A. de la Peña, R. C. González-Cano, C. Seoane, J. T. López Navarrete, J. L. Segura, J. Casado, M. C. Ruiz Delgado, J. Phys. Chem. C, 2014, 118, 9899. 6. M. Scheuble, Y. M. Gross, D. Trefz, M. Brinkmann, J. T. López Navarrete, M. C. Ruiz Delgado, and S. Ludwigs, Macromolecules, 2015, 48, 7049.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Detección de texto en escenas naturales

Along this thesis the actual state of the art algorithms of autonomous text localization and recognition in natural scene images are going to be analyzed, as well as methods for reaching a real-time execution on these matters are going to be developed, in order to create suitable algorithms for performing those tasks on mobile platforms. The developed algorithms for making the text localization faster are based on the detection of regions where is very likely to find text due to properties which are going to be detailed along this document. The main objective of this thesis is helping blind people to interact easily with their environment by given them a portable tool for obtaining more information of their surroundings.En el presente trabajo se pretende analizar los actuales algoritmos de estado del arte en detección y reconocimiento autónoma de texto en imágenes de escenas naturales, así como agilizar su ejecución para que puedan ser procesados por plataformas móviles en tiempo real, debido a que dichos algoritmos requieren una potencia de computación elevada para poder ejecutarse de forma rápida. Para alcanzar el objetivo propuesto se han desarrollado algoritmos de bajo coste computacional cuya función se basa en la selección de zonas de la imagen donde la probabilidad de encontrar texto es alta, debido a ciertas características que se detallaran a largo del presente documento. La finalidad de este trabajo es ayudar a las personas invidentes a interactuar más fácilmente con su entorno, proporcionándoles una herramienta que les permita ser capaces de obtener más información y que pueden llevar a cualquier lugar cómodamente gracias al poder de procesamiento de los nuevos teléfonos inteligentes.López González, R. (2016). Detección de texto en escenas naturales. http://hdl.handle.net/10251/92594TFG

El problema paramétrico del emparejamiento en grafos y problema de emparejamiento con dos objetivos

The minimum (maximum) matching problem is a fundamental problem in combinatorial optimization. The special structure of matching found by Edmonds allows to use different approximations. The idea of this work is to present a general insight of the matching problem, different sorts of algorithms for solving its original and the bi-objective formulations and a computational approach. In section 1 we describe the problem, its applications and the Grötschel-Holland algorithm (for solving using linear programming). In section 2 we introduce the theoretical background necessary for understanding the SAP algorithm and the sensitive analysis. In section 3 we implement some methods in Python 3.7 with Gurobi to study their computational properties and sensitive analysis. In section 4 we present our conclusions.El problema del emparejamiento es una de las cuestiones clásicas de la Programación Matemática. En este trabajo desarrollamos un extenso análisis sobre el trasfondo teórico de ciertos métodos para resolverlo, tanto en su formulación original, como en la formulación biobjetivo. Tras una presentación inicial del problema, presentamos una primera aproximación a la resolución del problema mediante la Programación Lineal conocida como el algoritmo de Grötschel-Holland. Seguidamente, veremos numerosas aplicaciones que motivan el interés del problema. En el segundo capítulo nos centramos en los conceptos y la estructura intrínseca del problema del emparejamiento, la cuál nos permite finalmente detallar el algoritmo del SAP. Además, presentamos el método de reoptimización propuesto por Derigs para este algoritmo. El tercer epígrame lo dedicamos a realizar un análisis computacional. Implementamos en Python 3.7 distintos métodos de resolución del problema del emparejamiento con el fin de reportar una comparativa entre ellos. Finalmente, llevamos a cabo un análisis de sensibilidad del problema original y la versión biobjetivo. Finalmente, en el cuarto capítulo presentamos las conclusiones.Universidad de Sevilla. Máster Universitario en Matemática

Safety of permanent pacemaker implantation: a prospective study

Although pacemaker implantation is considered to be low risk, it is not exempt from complications and technical failures during the procedure, both in the short and long term, and the complications that such patients may present remain unknown. The aim has been to analyze the complication rates associated with permanent pacing and to identify if these differ between patients with or without previous antithrombotic therapy. We used a prospective, single center, observational study of 310 adult patients with indications of permanent pacing. They were hospitalized from 1 January to 31 December 2014 and followed up for 6 months after the pacemaker implant. The participants were distributed into two groups according to the antithrombotic therapy prior to the implant. The most frequent major complications were pneumothorax (3.87%) and lead dislodgement (8.39%), while superficial phlebitis (12.90%) and uncomplicated hematomas (22.58%) were presented as the most recurrent minor complications. Hematomas were the most frequent minor complication in the antithrombotic therapy cohort, and shoulder pain was reported as the most recurrent minor complication in the non-exposed group. Finding out about complications in pacemaker implants enables a complete view of the process, and hence the prioritization of actions aimed at improving safety and reducing associated risks