Modelling shell and oscillation mark formation during continuous casting via explicit incorporation of slag infiltration

The development of reliable numerical models is vital to improve the quality of continuously cast products and to increase the productivity of the casting machine. In order to provide accurate predictions, these models must include detailed descriptions of the physical phenomena occurring inside the mould, such as metal flow, heat transfer and solidification. However, these topics are often treated separately during modelling due to their complexity. This has a negative impact on the accuracy of the predictions. To address this issue, a numerical model capable of coupling the flow dynamics with both the heat transfer to the mould walls and solidification has been developed. The 2‐dimenional model is based on a commercial CFD code that solves the Navier‐Stokes Equations coupled with a Volume of Fluid interface tracking technique for the multiphase system slag‐steel‐air under transient conditions within a conventional slab mould. The use of an extremely fine mesh in the meniscus region (~50 μm) allows, for the first time, the explicit calculation of liquid slag infiltration into the shell‐mould gap. Heat transfer through the solid mould faces and mould oscillation were also included in the model to provide a more realistic representation of the process. The model developed was tested in two case studies. In the first case, the predicted values were compared to prior numerical models and laboratory experiments directed to casting of conventional slabs. Excellent agreement was found for characteristics such as slag film development and heat flux variations during mould oscillation. Furthermore, predicted values for shell thickness, consumption and heat flux were also found to be in good agreement with plant measurements. The findings of this case study provided improved, fundamental understanding of the mechanisms involved in slag infiltration and solidification inside the mould and how these affect key process parameters, such as powder consumption and shell growth. The second case study consisted of a sensitivity study, where casting conditions (e.g. casting speed, mould cooling, steel/slag properties and oscillation settings) were varied in the simulations to determine their effect on both powder consumption and the formation of defects. The simulations predicted the initial formation of typical casting defects known as oscillation marks, without the aid of any external data fitting. The key result drawn from the sensitivity study was the determination of simple rules for the calculation of consumption, heat flux and defect formation as a function of the casting conditions. This opens the possibility of using the model as a diagnostic tool and for process optimisation

Existing con el Lobo, Traversing la Frontera con Mis Nepantla Coyotes, y Buscando la Vida del Zorro: An Autoethnographic Exploration of a Chicano in Academia

This dissertation is the experience of my life, an evolution of pláticas I have had con mis coyotes, my Nepantlero guides. I am one Chicano navigating through the mechanisms of a coercive and hegemonic system which limits our advancement in the academy. My ontology, epistemology, and axiology stem from my cultural and family foundations which I explore through the application of Testimonio. The dissertation consists of several chapter, first a description of the theoretical underpinnings which bolster my approach. I then guide you in a journey along a path of my discovery. My approach to how this study will be conducted is centered on a Chicano/Pocho stylism. I establish this stylism as grounded in my axiological belief about the need to serve, the epistemological belief that this work is empowering and liberating to me, and that ontologically this work is about barrier removals. I argue that my story is above all other sources of data, that my knowledge is valuable based upon the sources of its origin, and that Testimonio is the most appropriate means by which to share/explore/discover me. I provide my own version of an epic poem providing a realization of a Chicano experience in higher education. I then explore the poem through the stories of my life to provide a context for you to understand me. I address the multiple constituencies involved in my work through the form of an epistolary. I close my work by introducing the need for iterations, a reintroducing of the element of the circle. A circle allows us to review, or revisit for additional interpretations and understanding. Summarizing, this dissertation seeks to give me the opportunity to describe the context in which I exist and the forces that have impacted and shaped me. I reflect here on the data collection possibilities. Through this plática, using text both multifaceted and interdisciplinary—mis cuentos—I engage in the cogitation of approaches, principles, and information

Stress Reactivity in Humans and Animals: Two Meta-Analyses

International Journal of Exercise Science 6(2) : 144-156, 2013. Previous meta-analyses examining the effects of exercise on stress reactivity have included methodologically weak studies; we therefore conducted a meta-analysis utilizing more stringent inclusion criteria. An analysis of 33 randomized controlled trials involving humans (N = 1,252) revealed a moderate effect (ES = -0.31; 95% CI = -.43, -.20) for exercise as a method to reduce stress reactivity. An additional analysis with 27 randomized controlled trials of physical activity in animals (N = 462) also revealed a moderate reduction (ES = -0.33; 95% CI = -0.15, -0.52) in stress reactivity. The combined results of these analyses indicate that exercise diminishes the negative effects of increased reactivity to stressors

Possible implications of an accessory abductor digiti minimi muscle: a case report

<p>Abstract</p> <p>Background</p> <p>Accessory ADM was first reported in 1868 although muscular, vascular and nervous variations of the hypothenar eminence are rare, contrary to anomalous muscles in the wrist which are relatively common.</p> <p>Case presentation</p> <p>This case report presents a bilateral variation of an accessory abductor digiti minimi muscle in a male specimen. Ulnar artery and ulnar nerves were taken into account regarding their position and trajectory related to this variation.</p> <p>Conclusion</p> <p>Muscle size may be an important factor in considering whether a variation is able to produce neurovascular compression and clinical implications.</p

Variations of the origin of collateral branches emerging from the posterior aspect of the brachial plexus

<p>Abstract</p> <p>Background</p> <p>The frequency of variation found in the arrangement and distribution of the branches in the brachial plexus, make this anatomical region extremely complicated. The medical concerns involved with these variations include anesthetic blocks, surgical approaches, interpreting tumor or traumatic nervous compressions having unexplained clinical symptoms (sensory loss, pain, wakefulness and paresis), and the possibility of these structures becoming compromised. The clinical importance of these variations is discussed in the light of their differential origins.</p> <p>Methods</p> <p>The anatomy of brachial plexus structures from 46 male and 11 female cadaverous specimens were studied. The 40–80 year-old specimens were obtained from the Universidad Industrial de Santander's Medical Faculty's Anatomy Department (dissection laboratory). Parametric measures were used for calculating results.</p> <p>Results</p> <p>Almost half (47.1%) of the evaluated plexuses had collateral variations. Subscapular nerves were the most varied structure, including the presence of a novel accessory nerve. Long thoracic nerve variations were present, as were the absence of C5 or C7 involvement, and late C7 union with C5–C6.</p> <p>Conclusion</p> <p>Further studies are needed to confirm the existence of these variations in a larger sample of cadaver specimens.</p

Radiative non-isothermal Bondi accretion onto a massive black hole

In this paper, we present the classical Bondi accretion theory for the case of non-isothermal accretion processes onto a supermassive black hole (SMBH), including the effects of X-ray heating and the radiation force due to electron scattering and spectral lines. The radiation field is calculated by considering an optically thick, geometrically thin, standard accretion disk as the emitter of UV photons and a spherical central object as a source of X-ray emission. In the present analysis, the UV emission from the accretion disk is assumed to have an angular dependence, while the X-ray/central object radiation is assumed to be isotropic. This allows us to build streamlines in any angular direction we need to. The influence of both types of radiation is evaluated for different flux fractions of the X-ray and UV emissions with and without the effects of spectral line driving. We find that the radiation emitted near the SMBH interacts with the infalling matter and modifies the accretion dynamics. In the presence of line driving, a transition resembles from pure type 1 & 2 to type 5 solutions (see Fig2.1 of Frank etal. 2002), which takes place regardless of whether or not the UV emission dominates over the X-ray emission. We compute the radiative factors at which this transition occurs, and discard type 5 solution from all our models. Estimated values of the accretion radius and accretion rate in terms of the classical Bondi values are also given. The results are useful for the construction of proper initial conditions for time-dependent hydrodynamical simulations of accretion flows onto SMBH at the centre of galaxies.Comment: 10 pages, 10 figures, Accepted to be published in A&

Las secuencias didácticas, una alternativa para el aprendizaje del concepto de función

El aprendizaje del concepto de función siempre ha estado ligado a su expresión algebraica, la elaboración de tablas, su representación gráfica y a la solución de ejercicios; aspectos que desarrollan habilidades cognitivas dejando de lado el desarrollo de competencias. Las secuencias didácticas emergen desde el enfoque socioformativo como medio para dinamizar el proceso de aprendizaje, en caso particular, del concepto de función y sus transformadas. Apoyados de la formación de expresiones faciales se construyó una secuencia didáctica conformada de tres sesiones; en la primera se presenta el software Scientific Workplace 5.5 y se ilustran algunas funciones, en la segunda se realiza la simulación de una imagen facial y a partir de ella se construye el concepto de función y sus transformadas

Admisibilidad y pertinencia de la prueba en materia civil

Múltiples conceptos se nos han dado ya por los procesalistas acerca de lo que debemos entender por prueba. Los partidarios de interpretar únicamente el sentido estricto del vocablo nos proporcionan una definición que se fundamenta en lo etimológico. Así, según Caravantes, para unos la palabra prueba viene del adverbio probe, que equivale en castellano a honradamente, ya que el que alega una cosa y la prueba obra con honradez; y para otros, procede de la palabra latina probandum, que es lo mismo que recomendar, probar, experimentar, patentizar o hacer fe

Bloques lógicos: estrategia didáctica para el aprendizaje del concepto de permutación y combinatoria

En el espacio académico “Estadística y Probabilidades” que se orienta en el sexto semestre de la licenciatura en matemáticas y física se abordó el aprendizaje de los conceptos permutación y combinación encontrándose que los estudiantes confunden dichos conceptos, para lo cual se diseñó el juego “Bloques lógicos” los cuales consisten en piezas geométricas, cuadrados, rectángulos, círculos y triángulos, de diferentes colores y a partir de ellos se construyó una secuencia didáctica que permitiera mejorar el aprendizaje de dichos conceptos. Se trabajó con un total de cuarenta y cinco (45) estudiantes de las Instituciones educativas San Francisco de Asís y Comfaca del municipio de Florencia –Caquetá–