Theory of homogeneous vapour condensation and surface deposition from boundary layers

Homogeneous condensation of vapours mixed with a carrier gas in the stagnation point boundary layer flow near a cold wall is considered. There is a condensation region near the wall with supersaturated vapour. Assuming that the surface tension times the molecular area is much larger than the thermal energy far from the wall, droplets are nucleated exclusively in a narrow nucleation layer where the Zeldovich flux of clusters surpassing the critical nucleus size is at a maximum. The vapour condenses in the free molecular regime on the droplets, which are thermophoretically attracted to the wall. Unlike the narrow condensation region for heterogeneous condensation on solid particles, in the case of homogeneous condensation the condensation region is wide even when the rate of vapour scavenging by droplets is large. A singular perturbation theory of homogeneous vapour condensation in boundary layer flow approximates very well the vapour and droplet density profiles, the nucleation layer and the deposition rates at the wall for wide ranges of the wall temperature and the scavenging parameter B. A key point in the theory is to select a trial vapour number density profile among a one parameter family of profiles between an upper and a lower bound. The maximum of the Zeldovich flux for supercritical nuclei provides the approximate location of the nucleation layer and an approximate droplet density profile. Then the condensate number of molecules and the vapour density profile are calculated by matched asymptotic expansions that also yield the deposition rates. For sufficiently large wall temperatures, a more precise corrected asymptotic theory is given.This work was supported by the Spanish Ministerio de Economía y Competitividad grant FIS2011-28838-C02-01 and by the Autonomous Region of Madrid grant P2009/ENE-1597 (HYSYCOMB).Publicad

The Effect of NAFTA on Mexican Agricultural Exports to the United States: The Case of Coffee Beans, 1970-2003

Since its implementation in 1994, NAFTA\u27s impacts on trade have been extensively and positively evaluated at an aggregate level, but not so much at a regional or sectorial level. Through time series analysis, this paper studies NAFTA\u27s impact on Mexican exports of coffee beans to the U.S. The study shows a NAFTA\u27s positive, although short-lasting effect (for two-three years) on the studied variable, mainly because the international market of coffee beans used to function on a quota system, thus preventing Mexico from capitalizing (and furthering) on the comparative advantage derived from its location, close to the U.S. market

The Necessary Conciliation of Personal Income Tax in the Family Sphere with Constitutional Principles

Universidad de Sevilla. Doble Máster Universitario en Abogacía y Asesoría Jurídico-Mercantil, Fiscal y Labora

Influence of primary-particle density in the morphology of agglomerates

Agglomeration processes occur in many different realms of science, such as colloid and aerosol formation or formation of bacterial colonies. We study the influence of primary-particle density in agglomerate structures using diffusion-controlled Monte Carlo simulations with realistic space scales through different regimes (diffusion-limited aggregation and diffusion-limited colloid aggregation). The equivalence of Monte Carlo time steps to real time scales is given by Hirsch's hydrodynamical theory of Brownian motion. Agglomerate behavior at different time stages of the simulations suggests that three indices (the fractal exponent, the coordination number, and the eccentricity index) characterize agglomerate geometry. Using these indices, we have found that the initial density of primary particles greatly influences the final structure of the agglomerate, as observed in recent experimental works.This work has been supported by the Spanish Ministerio de Economía y Competitividad Grant No. FIS2011-28838-C02-01 and by the Autonomous Region of Madrid Grant No. P2009/ENE-1597 (HYSYCOMB).Publicad

Análisis clínico retrospectivo a cinco años de restauraciones de prótesis fija dentosoportadas preparadas sin línea de terminación

Las prótesis fijas dentosoportadas (PFDs) han sido durante muchos años el tratamiento de elección, cuando no es posible realizar restauraciones con resinas compuestas o materiales similares, debido a cantidad del tejido a sustituir, o cuando necesitamos reponer una o varias piezas. A pesar del gran impacto de los implantes dentales, las PFDs aún tienen un amplio campo para ser utilizadas como primera opción, o como alternativa en la reposición de dientes perdidos. Hoy en día, lo más habitual es preparar los dientes que van a recibir una restauración fija, con líneas de terminación gingivales, sobre las cuales los técnicos asientan los materiales de restauración. Estas prótesis, han sido ampliamente estudiadas desde hace décadas. Sin embargo, el uso de las líneas de terminación puede presentar ciertos problemas como la dificultad de tallarlas, especialmente cuando los dientes presentan caries en las porciones más apicales, o la dificultad de reproducirlas con las impresiones, entre otros..

La armonización del Derecho, concepto y críticas en cuanto a su implementación

El presente trabajo de investigación tiene como objetivo el estudio de la armonización del derecho comercial internacional, analizando sus objetivos, características, tipologías y algunas de las críticas que han sido formuladas al proceso armonizador

Diseño del sistema de acondicionamiento de aire para el Auditorio Judicial Miguel Blanco Quirós del Organismo de Investigación Judicial

Proyecto de Graduación (Licenciatura en Ingeniería en Mantenimiento Industrial) Insituto Tecnológico de Costa Rica, Escuela de Ingeniería en Mantenimiento Industrial, 2017.The purpose of this project is to design the air conditioning system for the Miguel Blanco Quirós Judicial Auditorium of the OIJ, whose problem is that there is currently a system that does not comply with the environmental aspects that the country has committed to adopt, in addition to having an age of 15 years whose deterioration has increased over time, which has caused the system to be subject to continuous repairs. In order to solve the aforementioned problem, the thermal load of the enclosure was calculated, the pipeline and duct system was sized, the generation equipment and terminal units were selected, the design drawings were drawn up and the project budget analysis was carried out, all in accordance with design criteria of the ASHRAE Standard, as well as with the legal framework that governs the health and environmental aspects in this type of designs. It was determined that the energy to be compensated by the system is 107.001,23 kcal/h (35,36 tons of refrigeration) and its calculation was verified by thermal load calculation software, which the project cost is $133.298 (₡ 76.294.443,28) and that the savings to implement the project is 21,39$ 3.769,64/Ton (₡ 2.157.589,52/Ton), a cost per area of $297,89/m2 (₡ 170.500,90/m2) and a cost of$ 305,03/occupant (₡ 174.586,83/occupant).Poder Judicia

Evaluación experimental de la co-digestión anaeróbica de contenido ruminal y estiércol bovino en un reactor rotativo

Colombia is a country famously known for its biodiversity and high potential in agricultural production, Cordoba is a department labeled in Colombia for its high production of products that come from the field, the main economic activity in this place is livestock, then followed by agriculture. These activities leave organic residues such as manure and bovine rumen content, which can have a high energy potential. This research examined the behavior of anaerobic digestion and co-digestion, considering bovine manure (E) and rumen content (CR) as residual biomass. Samples with a ratio of 30% rumen content and 70% bovine manure (E70-CR30) and another complete with bovine manure (E100) were also evaluated. During the experimental evaluation, 2 samples were analyzed for E70-CR30 and another for E100 to analyze the parameters of pressure, pH and temperature, in addition to evaluating the behavior of biogas every week. As a last step, the biogas was characterized by means of a chromatography test to evaluate the calorific value (LHV) and to know the biogas yield. The results of the experiment showed that the E70-CR30 combination has a 64% higher CH4 production compared to the E100 mixture.Colombia es un país famosamente conocido por su biodiversidad y alto potencial en producción de agrícolas, Córdoba es un departamento etiquetado en Colombia por su alta producción de productos que provienen del campo, la principal actividad económica en este lugar es la ganadería, luego le sigue la agricultura. Estas actividades dejan residuos orgánicos como el estiércol y contenido ruminal bovino, que pueden tener un alto potencial energético. Esta investigación se examinó el comportamiento de la digestión y codigestión anaerobia, considerando el estiércol bovino (E) y contenido ruminal (CR) como biomasa residual. Asimismo, se evaluó muestras con una relación de 30% contenido ruminal y 70% estiércol bovino (E70-CR30) y otra completa de estiércol bovino (E100). Durante la evaluación experimental se analizaron 2 muestras para E70-CR30 y otra para E100 para los analizar los parámetros de presión, pH y temperatura, además de evaluar cada semana el comportamiento de biogás. Como última medida se caracterizó el biogás mediante un ensayo de cromatografía, para evaluar el poder calorífico (LHV) y conocer el rendimiento del biogás. Los resultados del experimento arrojaron que la combinación E70-CR30 tiene una producción de 64% mayor de CH4 en comparación con la mezcla E100