Dark Matter Halos and Evolution of Bars in Disk Galaxies: Varying Gas Fraction and Gas Spatial Resolution

We conduct numerical experiments by evolving gaseous/stellar disks embedded in live dark matter halos aiming at quantifying the effect of gas spatial resolution and gas content on the bar evolution. Three model sequences have been constructed using different resolutions, and the gas fraction has been varied along each sequence within the range of f g = 0%-50%, but keeping the disk and halo properties unchanged. We find that the spatial resolution becomes important with an increase in the gas content. For the higher resolution model sequences, we observe a bimodal behavior in the bar evolution with respect to the gas fraction, especially during the secular phase of this evolution. The switch from the gas-poor to gas-rich behavior is abrupt and depends on the resolution used, being reasonably confined to f g ~ 5%-12%. The diverging evolution has been observed in nearly all basic parameters characterizing bars, such as the bar strength, central mass concentration, bar vertical buckling amplitude, bar size, etc. We find that the presence of the gas component severely limits the bar growth and affects its pattern speed evolution. Gas-poor models display rapidly decelerating bars, while gas-rich models exhibit bars with constant or even slowly accelerating tumbling. We also find that the gas-rich models have bar corotation (CR) radii within the disk at all times, in contrast with gas-poor and purely stellar disks. In addition, the CR-to-bar size ratio is less than 2 for gas-rich models. Next, we have confirmed that the disk angular momentum within the CR remains unchanged in the gas-poor models, as long as the CR stays within the disk, but experiences a sharp drop before leveling off in the gas-rich models. Finally, we discuss a number of observed correlations between various parameters of simulated bars, such as between the bar sizes and the gas fractions, between the bar strength and the buckling amplitude, and between the bar strength and its size, etc. Published copy located at:https://iopscience.iop.org/article/10.1088/0004-637X/719/2/147

Dark Matter Halos and Evolution of Bars in Disk Galaxies: Collisionless Models Revisited

We construct and evolve families of steady-state models of stellar disks embedded in live DM halos, in order to study the dynamical and secular phases of bar evolution. These models are tested against those published in the literature in order to extend them and include the gaseous component in the follow up paper. We are interested in the angular momentum (J) redistribution in the disk-halo system. We confirm the previous results and quantify for the first time the dual role that the DM halos play in the bar evolution: more centrally concentrated halos dilute the dynamical processes, such as spontaneous bar instability and vertical buckling instability, and slowdown the J transfer, while facilitating it in the secular phase. Within the corotation radius (Rcr), the disk J remains nearly constant, as long as Rcr stays within the disk -- a sign that the lost J to the outer disk and the halo is being compensated by an influx of fresh J due to the outward motion of Rcr. This is feasible as long as the bar slowdown dominates the loss of J inside Rcr. We find that in some models the bar pattern speed stalls for prolonged time periods when Rcr is located outside the disk. This phenomenon appears concurrent with the near absence of J transfer between the disk and the halo. Furthermore, we confirm that stellar bars generally display the corotation to bar size ratios in the range of ~1-1.4, but only between the times of the first buckling and Rcr leaving the disk. The corotation-to-disk size ratio emerges as an important dynamic discriminator between various stages of barred disk evolution. Finally, we analyze a number of correlations between the basic parameters of a barred disk and a halo, some already reported in the literature and some new.Comment: 15 pages, 20 figures, to be published by the Astrophysical Journal; small corrections following the referee comment

Dark Matter Halos and Evolution of Bars in Disk Galaxies: Varying Gas Fraction and Gas Spatial Resolution

We conduct numerical experiments by evolving gaseous/stellar disks embedded in live dark matter halos aiming at quantifying the effect of gas spatial resolution and gas content on the bar evolution. Model sequences have been constructed using different resolution, and gas fraction has been varied along each sequence within fgas=0%-50%, keeping the disk and halo properties unchanged. We find that the spatial resolution becomes important with an increase in `fgas'. For the higher resolution model sequences, we observe a bimodal behavior in the bar evolution with respect to the gas fraction, especially during the secular phase of this evolution. The switch from the gas-poor to gas-rich behavior is abrupt and depends on the resolution used. The diverging evolution has been observed in nearly all basic parameters characterizing bars, such as the bar strength, central mass concentration, vertical buckling amplitude, size, etc. We find that the presence of the gas component severely limits the bar growth and affects its pattern speed evolution. Gas-poor models display rapidly decelerating bars, while gas-rich models exhibit bars with constant or even slowly accelerating tumbling. The gas-rich models have bar corotation (CR) radii within the disk at all times, in constrast with gas-poor and purely stellar disks. The CR-to-bar size ratio is less than 2 for gas rich-models. We have confirmed that the disk angular momentum within the CR remains unchanged in the gas-poor models, as long as the CR stays within the disk, but experiences a sharp drop before leveling off in the gas-rich models. Finally, we discuss a number of observed correlations between various parameters of simulated bars, e.g., bar sizes and gas fractions, bar strength and buckling amplitude, bar strength and its size, etc.Comment: 13 pages, 13 figures, to be published by the Astrophysical Journal; minor changes following the referee repor

Rehabilitación Energética del edificio H de la Escuela Técnica Superior de Ingeniería Industrial de Barcelona (ETSEIB)

El objetivo de esta tesis es proponer medidas de mejora para el Edificio H de la Escuela Técnica Superior de Ingeniería Industrial de Barcelona, enfocadas principalmente en la eficiencia energética, el impacto ambiental y los potenciales ahorros económicos en el edificio, siendo complementadas por la búsqueda de la mejora en la calidad del confort al interior de los espacios. Las propuestas se plantean a partir del análisis del consumo actual de energía, el comportamiento térmico de la envolvente del edificio y el funcionamiento de los sistemas e instalaciones para climatización (calefacción y refrigeración) e iluminación. Así, se plantea una propuesta de rehabilitación energética mediante diferentes medidas de mejora como lo son la incorporación de un sistema de aislamiento de la envolvente, la sustitución de la ventanería, el cambio de luminarias y la incorporación de un nuevo sistema centralizado de calefacción y refrigeración. El conjunto de estas mejoras logra un ahorro energético al reducir el consumo en un 48,4%, obtenido en gran parte por el ahorro de demanda energética generado bajo la medida de mejora de la envolvente con una reducción importante de demanda para calefacción y refrigeración de 54,2%. El documento se complementa con conclusiones sobre el estado actual de la edificación, sobre las medidas de mejora y sobre la aplicación de este tipo de proyectos en Colombia. Estas propuestas promueven un edificio de consumo energético casi nulo, conocido como NZEB (Nearly Zero Energy Building), estando dentro del marco normativo del Código Técnico de la Edificación y logrando enmarcarse en los objetivos del Plan UPC Energía 2020 al reducir la demanda energética y las emisiones de CO2 en las edificaciones pertenecientes a la universidad.The goal of this thesis is to propose improvement measures for the H Building of the Barcelona School of Industrial Engineering, focused mainly on energy efficiency, environmental impact and potential economic savings in the building, being complemented by the search for the improvement in quality of comfort inside the spaces. The improvement proposals are based on the analysis of current energy consumption, the thermal behavior of the building envelope and the operation of systems and installations for heating, cooling and lighting. Thus, a proposal for energy rehabilitation is proposed through different improvement measures such as the incorporation of an envelope insulation system, the replacement of glazing elements, the change of luminaires and the incorporation of a new centralized heating and cooling system. All these improvements would achieve energy savings by reducing consumption by 48.4%, largely obtained by the reduction of energy demand generated under the envelope improvement measure with a significant reduction in demand for heating and cooling of 54.2% The document is complemented by conclusions on the current state of the building, on improvement measures and on the application of this type of projects in Colombia. These proposals promote an almost zero energy consumption building, kown as NZEB (Nearly Zero Energy Building), being within the regulatory framework of the Technical Building Code and achieving the goals of the UPC Energy 2020 Plan by reducing energy demand and CO2 emissions in the buildings belonging to the university

La generalización como eje transversal en el currículo de matemáticas

Este proyecto de investigación se realiza en la Universidad de Antioquia en el marco de la Licenciatura en Educación Básica con Énfasis en Matemáticas, en él se pretende generar reflexiones que permitan a los maestros utilizar la generalización como un proceso que se encuentra inmerso en toda actividad matemática. En este documento presentaremos los avances del marco teórico del proyecto y el rastreo de libros de texto de matemáticas de la educación básica

William W. Loring en: Trayectoria Militar y Escritural en Estados Unidos y Egipto

William W. Loring fought in the Wars of Florida (1835-1842, 1855-1858), the Mexican-American War (1846-1848), and the Civil War (1861-1865) that helped in the expansion and unity of the American territory as well as in the invasion of Abyssinia with the Egyptian army. Loring’s historical role is valuable not only for his participation in key wars of the Nineteenth Century but for the reflexive components of his writing that examine the theme of the military hero and the impact of armed conflicts in both victims and perpetrators

An intelligent approach to design and development of personalized meta search: Recommendation of scientific articles

In this article we present a method to recommend articles scientists taking into account their degree of generality or specificity. In terms of methodology, two approaches are presented to recommend articles based on Topic Modeling. The first of these is based on the divergence of topics that are given in the documents, while the second is based on the similarity between these topics. After a validation process it was demonstrated that the proposed methods are more efficient than the traditional methods

Sale forecast for basic commodities based on artificial neural networks prediction

The objective of this paper is to carry out the comparison and selection of a method to forecast sales of basic food products efficiently. The source of data comes from a set of popular markets in the main departments of Colombia. The methods and methodologies used are: Hold Method, Winters, the Box Jenkins methodology (ARIMA) and an Artificial Neural Network. The results show that the artificial neural network obtained a better performance achieving the lowest mean square error

Análisis del esfuerzo residual en concreto para pavimento rígido reforzado con fibras metálicas y sintéticas

A través del presente trabajo, luego de efectuar una exploración general respecto a los conceptos asociados con los diferentes tipos de fibras empleadas y su aplicación en diversas clases de concreto, se efectúa la explicación detallada acerca de los ensayos realizados, a fin de generar un análisis y valoración del esfuerzo residual en concreto para pavimento rígido reforzado con fibras metálicas y sintéticas. Como resultado de los ensayos realizados, se podrá obtener un punto de vista objetivo, que comparado bajo términos de funcionalidad, eficiencia y rentabilidad, permitirá el desarrollo y generación de una nueva forma de mezcla que facilite el desarrollo de estructuras en pavimentos

Database knowledge discovery In marketing companies

In recent years, technological development in both the computing and data transmission fields has allowed the storage and management of large volumes of data. Today, businesses move in highly competitive and continuous changing environments. Market dynamics requires companies to handle the right information at the right time so that managers can make the appropriate business decisions. For this reason, companies have understood that the large volumes of data residing in their systems can, and must, be analyzed and exploited to gain new knowledge. This research develops a Database Knowledge Discovery process for assisting in the decision-making of a group of distribution companies. In this sense, subjects related to Data Mining and its application in the environment of economic, financial, and management indicators are described, obtaining models of association and grouping to support the work of managers at different levels of the organization