Modelado Matemático Y Simulación De Un Reactor Fotocatalítico Para La Oxidación Selectiva De Alcohol Bencílico

En el Capítulo 1 se analiza la teoría que sustenta a cada uno de los modelos que se incorporaron a los programas realizados, así como otros modelos presentes en las referencias consultadas y reportadas en la bibliografía. Al final del Capítulo 1 se describe el planteamiento del problema y los objetivos de esta Tesis. En el Capítulo 2 se presenta el desarrollo matemático del Modelo de Cuatro Flujos de la Radiación, el desarrollo de la ecuación cinética de reacción y se presenta un método numérico para resolver la ecuación de diseño del reactor fotocatalítico en estado transitorio. Además, se presentan los modelos de emisión de la radiación y el modelo de agitación, que son modelos ya desarrollados en la bibliografía. También se presentan las condiciones frontera y las suposiciones empleadas en cada modelo. Con los modelos obtenidos se analizó el efecto de la carga de catalizador, potencia de la lámpara, las dimensiones del reactor y la velocidad de agitación. Estos resultados son mostrados en el Capítulo 3 en donde se evalúa el efecto que tiene cada factor sobre la conversión. En el Capítulo 4 se establecen las conclusiones pertinentes de acuerdo con los resultados obtenidos de la simulación. Al final, se anexa el Artículo científico que fue enviado para su revisión a la revista científica Fuel.La fotocatálisis es un proceso que se basa en la absorción de la energía radiante visible o ultravioleta por un fotocatalizador, el cual promueve la reacción de fotoxidación. Esta tecnología se emplea para producir aldehídos a partir de sus correspondientes alcoholes, entre otras aplicaciones. Factores como la geometría, la distribución de la luz, tipo de flujo, entre otros, influyen sobre el rendimiento final de la reacción fotocatalítica. Este proyecto de investigación tuvo como objetivo principal el estudio, modelado y simulación de un reactor fotocatalítico por lotes para la oxidación selectiva del alcohol bencílico, mediante los software comerciales Comsol Multiphysics 4.3 ® y Matlab R2013a®. El modelo matemático establecido para simular el comportamiento del reactor fotocatalítico, comprende a su vez los siguientes sub-modelos: a) Emisión de la radiación; b) Absorción y dispersión de la radiación; c) Modelo hidrodinámico; d) Cinética de reacción heterogénea; e) Ecuación de diseño del reactor fotocatalítico en estado no estacionario. Estos modelos están constituidos por sistemas de ecuaciones diferenciales parciales y expresiones algebraicas. Así mismo, se establecieron las condiciones de frontera pertinentes y las consideraciones que permiten la resolución de los sub-modelos. Es importante resaltar que en este trabajo se propuso un modelo de absorción y dispersión de la radiación en coordenadas cilíndricas, denominado ―Modelo de Cuatro Flujos de la radiación‖, el cual consiste en un sistema de ecuaciones diferenciales que permiten predecir la velocidad la velocidad volumétrica local de absorción de fotones, LVRPA, por sus siglas en inglés. Se demostró que este modelo provee datos consistentes con los obtenidos mediante otros métodos como el de Montecarlo y el Modelo de Seis Flujos. Posteriormente se obtuvo una ecuación cinética que permite establecer la dependencia de la velocidad de reacción con la LVRPA. Se determinó que la velocidad de reacción depende de la LVRPA dentro del reactor, la cual varía en el volumen de reacción, ya que existen zonas obscuras en donde la radiación no logra excitar a las partículas de catalizador. Por este motivo fue necesario establecer una ecuación de diseño que considerara las variaciones de velocidad de reacción dentro del reactor. Los programas elaborados para resolver el modelo obtenido se emplearon para predecir la cantidad óptima de catalizador, el efecto que tienen sobre la conversión la potencia de la lámpara, la carga de catalizador, y las dimensiones del reactor

Implications of model error for numerical climate prediction

Numerical climate models constitute the best available tools to tackle the problem of climate prediction. Two assumptions lie at the heart of their suitability: (1) a climate attractor exists, and (2) the numerical climate model's attractor lies on the actual climate attractor, or at least on the projection of the climate attractor on the model's phase space. In this contribution, the Lorenz '63 system is used both as a prototype system and as an imperfect model to investigate the implications of the second assumption. By comparing results drawn from the Lorenz '63 system and from numerical weather and climate models, the implications of using imperfect models for the prediction of weather and climate are discussed. It is shown that the imperfect model's orbit and the system's orbit are essentially different, purely due to model error and not to sensitivity to initial conditions. Furthermore, if a model is a perfect model, then the attractor, reconstructed by sampling a collection of initialised model orbits (forecast orbits), will be invariant to forecast lead time. This conclusion provides an alternative method for the assessment of climate models

Sting jets in simulations of a real cyclone by two mesoscale models

The existence of sting jets as a potential source of damaging surface winds during the passage of extratropical cyclones has recently been recognized However, there are still very few published studies on the subject Furthermore, although ills known that other models are capable of reproducing sting jets, in the published literature only one numerical model [the Met Office Unified Model (MetUM)] has been used to numerically analyze these phenomena This article alms to improve our understanding of the processes that contribute to the development of sting jets and show that model differences affect the evolution of modeled sting jets A sting jet event during the passage of a cyclone over the United Kingdom on 26 February 2002 has been simulated using two mesoscale models namely the MetUM and the Consortium for Small Scale Modeling (COSMO) model to compare their performance Given the known critical importance of vertical resolution in the simulation of sting jets the vertical resolution of both models has been enhanced with respect to their operational versions Both simulations have been verified against surface measurements of maximum gusts, satellite imagery and Met Office operational synoptic analyses, as well as operational analyses from the ECMWF It is shown that both models are capable of reproducing sting jets with similar, though not identical. features Through the comparison of the results from these two models, the relevance of physical mechanisms, such as evaporative cooling and the release of conditional symmetric instability, in the generation and evolution of sting jets is also discusse

General guidelines of risk management for the guidance of fire detection system in the Metropolitan Business Center Horizontal Property

En el presente ensayo se exponen los principales aspectos de la gerencia de riesgos bajo la metodología propuesta por el Project Management Institute PMI y su incidencia en la administración del sistema automático de detección de incendios que opera en un conjunto de edificios de uso comercial denominado Centro Empresarial Metropolitano P.H. Este sistema actualmente demanda una actualización tecnológica, debido a que, lleva en operación 15 años aproximadamente, situación que al ser analizada desde la perspectiva de la gerencia de proyectos, en especial, desde la óptica de la gerencia de riesgos, aporta información de uso relevante para adelantar un proyecto de estas características en edificaciones habitadas, situación que incrementa los niveles de riesgo tanto del proyecto como de sus beneficiarios. Por lo tanto, la gerencia de riesgos facilita la identificación y gestión de las diferentes circunstancias adversas involucradas en la realización de este ensayo, involucrando a las partes interesadas en el mismo como los son sus copropietarios y ocupantes, permitiendo estimar con mayor precisión los recursos necesarios para desarrollarlo.In this essay the main aspects of risk management under the methodology proposed by the Project Management Institute PMI and its impact on the administration of automatic fire detection operates on a set of commercial buildings called Metropolitan Business Center H.P. This system currently demand a technological upgrade, because that has been in operation about 15 years and are being analyzed from the perspective of project management, especially from the perspective of risk management , provides information relevant use to advance a project of this nature in inhabited buildings , a situation that increases the risk levels for project and beneficiaries. Therefore, risk management facilitates the identification and guidance of the various adverse circumstances involved in conducting this essay, involving stakeholders as their owners and occupants, allowing more accurately estimate the resources to develop it

Estudio Multifactorial y simulación de la degradación fotocatalítica de un fármaco

Photocatalysis is an advanced oxidation process, which in recent decades has proven to be a suitable technology for water treatment, which allows the elimination of bio-resistant toxic organic compounds and achieve their complete mineralization; however, its industrial implementation has been hampered due to lack of clarity in its design and scaling; in addition to the difficulty of estimating the optical coefficients and parameters that intervene in the process of radiation absorption. Based on the above, it is important to develop calculation methods and computational tools to simulate the behavior of photocatalytic reactors, facilitate their study and select the most appropriate operating parameters that allow the process to be more efficient. In the present investigation, the photocatalytic degradation of paracetamol was experimentally performed. Mathematical modeling of the process was established to determine the intrinsic kinetic equation of photocatalytic degradation, which takes into account the effect of direct and indirect photolysis and that due to photocatalysis. And through computer simulation the impact of different parameters on the conversion was analyzed. In addition, a methodology was established to determine by simulation and experimental radiometric measurements optical coefficients and the coefficient of the phase function Henyey – Greenstein, under working conditions of the photocatalytic reactor employed. The parameters analyzed in this investigation were: a) Type of catalyst, since five different catalysts were analyzed: commercial TiO2 DP25, TiO2-Mo, TiO2-W and catalysts obtained from hydrotalcite-type compounds Mg-Zn-Al and Zn-Al; b) initial concentration of reagent; c) charge of catalyst; d) effect of the oxidizing agent; e) intensity of radiation emitted by the lamp and f) thickness of the reaction space. When experimentally performing the paracetamol degradation by UV light in the absence of a catalyst, it was found that paracetamol is susceptible to degradation by photolysis. For this reason it was necessary to modify the kinetic models proposed in the literature to take into account the degradation by photolysis. The results of the proposed kinetic model show a good concordance with the experimental data, both for the kinetics of degradation by photolysis and by photocatalysis using the TiO2 DP25 catalyst, since it was the only catalyst that presented catalytic activity under the conditions used in this investigation.CONACYT 269093, 22039

GovernIT: A Software for Decision-making Support on Automated IT Governance Models

We developed a software tool named GovernIT to support the creation and evolution of computer-driven Information Technology (IT) governance models. This software automates the design of decision-making grants to coordinate interactions among IT units. It also allows the assessment of business drivers and IT risks to automate the generation of implementation roadmaps for decision-support mechanisms. The software has been used by students of an IT Governance Course to assess undesirable IT behaviors for 21 organizations, to design their target IT governance model, and to generate their IT process implementation roadmap. The results of this implementation evidences the positive impact of dynamic governance models on IT risks and efficiency

A diagnosis of low-order dynamics in the atmosphere of Mars

Introduction: There is considerable evidence that shows that the Martian atmosphere behaves in a more regular fashion than its terrestrial counterpart [1, 2, 3, 4]. This evidence leads to the hypothesis of theMartian climate attractor being of a relatively low dimension, which, in turn, would imply the possibility of describing the state of the atmosphere by means of a relatively few degrees of freedom. We explore this hypothesis by assuming that the atmospheric total energy (TE), i.e. the sum of kinetic energy and total potential energy (gravitational potential energy plus internal energy), is confined in a few coherent structures which dynamically interact nonlinearly with each other

Transient teleconnection event at the onset of a planet-encircling dust storm on Mars

We use proper orthogonal decomposition (POD) to study a transient teleconnection event at the onset of the 2001 planet-encircling dust storm on Mars, in terms of empirical orthogonal functions (EOFs). There are several differences between this and previous studies of atmospheric events using EOFs. First, instead of using a single variable such as surface pressure or geopotential height on a given pressure surface, we use a dataset describing the evolution in time of global and fully three-dimensional atmospheric fields such as horizontal velocity and temperature. These fields are produced by assimilating Thermal Emission Spectrometer observations from NASA's Mars Global Surveyor spacecraft into a Mars general circulation model. We use total atmospheric energy (TE) as a physically meaningful quantity which weights the state variables. Second, instead of adopting the EOFs to define teleconnection patterns as planetary-scale correlations that explain a large portion of long time-scale variability, we use EOFs to understand transient processes due to localised heating perturbations that have implications for the atmospheric circulation over distant regions. The localised perturbation is given by anomalous heating due to the enhanced presence of dust around the northern edge of the Hellas Planitia basin on Mars. We show that the localised disturbance is seemingly restricted to a small number (a few tens) of EOFs. These can be classified as low-order, transitional, or high-order EOFs according to the TE amount they explain throughout the event. Despite the global character of the EOFs, they show the capability of accounting for the localised effects of the perturbation via the presence of specific centres of action. We finally discuss possible applications for the study of terrestrial phenomena with similar characteristics

La influencia de diversos elementos del contexto en el desempeño académico del alumno de administración

1 archivo PDF (12 páginas). magyeoipRESUMEN: Reconocer que las matemáticas son necesarias en ciertas áreas del conocimiento no siempre va acompañado de actitudes positivas hacia ellas. Al inicio de cada curso, los profesores comprobamos que muchos alumnos se muestran poco favorables hacia la materia, a pesar de que se acepta su papel en el desarrollo de la ciencia y su contribución a la solución de problemas sociales. Los docentes, por los comentarios de los alumnos, percibimos que las principales razones de este fenómeno están ligadas a sus experiencias previas. Diversos estudios indican bloqueos de tipo emocional o barreras psicológicas entre el estudiante y las matemáticas (Auzmendi, 1992) Otro autor (Gómez-Chacón, 2000) señala que muchos alumnos muestran temor ante la asignatura e incluso aversión, elementos que impiden el aprendizaje y la construcción de bases sólidas. Esta es una primera aproximación para comprender esta problemática que regularmente se presenta cuando los estudiantes inician cualquier curso de matemáticas. Analizamos las actitudes y percepciones hacia esta materia de los alumnos que cursan álgebra en el tronco divisional de Ciencias Sociales en la Universidad Autónoma Metropolitana de la unidad Xochimilco, por considerar que influyen en el aprendizaje de las matemáticas. Se aplicó un cuestionario a los estudiantes de la licenciatura en Administración en el trimestre 04-I y las preguntas se orientan hacia las experiencias en la educación media superior. Abstract: To admit that Mathematics is totally needed in some knowledge areas it is not always accompanied with positive attitude toward Mats. Teachers ascertain every course that many students do not have a good attitude toward Mats, even though they accept the Mats main roll in science growth and its contribution to solve social problems. From students’ comments, the teachers perceive that the main reasons of this issue are linked to the students’ previous experiences. Researches conducted indicate that there are emotional-psychological walls between students and Mats (Auzmendi, 1992). Another author (Gomez-Chacon, 2000) assures that many students show afraid and aversion which are elements hinder learning and the build of solid basis. This work is a first move to understand this trouble and we may see it when students start any Mats course. We analyze attitudes and perceptions toward Mats from students in the course of algebra in Common Subjects Division of Social Sciences in the Xochimilco unit of the Autonoma Metropolitana University; given the fact their experiences are elements influencing the Mats learning. A question papers was applied to students of Administration in quarter 04-I; questions were oriented to their media-high education experiences. PALABRAS CLAVE: Ciencias sociales, Administration KEYWORDS: Social Sciences, Administratio

DEVELOPMENT OF A DIELECTRIC ELECTRO ACTIVE POLYMER ROLL ACTUATOR WITH DIFFERENT BIASING ELEMENTS

This thesis presents the fabrication and characterization of a tubular Dielectric Electro-Active Polymer (DEAP) actuator system using different biasing mechanisms. DEAPs are attractive in the aerospace community due to their light weight, low electrical power consumption and no noise. A biasing mechanism is needed to supply the DEAP actuator with an optimal pre-load, and its design has a major impact on the overall actuator performance. The biasing elements considered are a conventional linear positive-stiffness bias (PSB) spring, and a constant force bias (CFB) spring. These biasing elements are paired with a roll DEAP actuator and experimentally tested under quasi-static and dynamic loading conditions with a focus on the stroke and blocked force capabilities. The experimental results indicate improvement in stroke using a CFB element but at the cost of blocked force. Work potential is found higher using a PSB than a CFB mechanism