An experimental and numerical study of flames in narrow channels with electric fields

The proceeding at: 14th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2014). Took at 2014, November, 18-21, in Awaji Island, Hyogo Japan. The event Web site in: http://powermems2014.org/The advancement of microscale combustion has been limited by quenching effects as flames cease to be much smaller than combustors. The long studied sensitivity of flames to electrical effects may provide means to overcome this issue. Here we experimentally and numerically investigate the potential of electric field effects to enhance combustion. The results demonstrate that, under specific conditions, externally electric fields will sustain combustion in structures smaller than the quenching distance. The analysis proposes a reduced mechanism to model this result and provides a study of the governing parameters. We find good qualitative agreement between the model and experiments. Specifically, the model is found to successfully capture the capacity to increase and decrease flame speed according to electric field magnitude and direction. Further, in both experiments and computations the sensitivity to electrical enhancement increases for more energetic mixtures. We do find that the model underpredicts the maximum achievable speed enhancement observed, suggesting that additional phenomena should be included to expand the range of conditions that can be studied.Publicad

Continuity or discontinuity of hillfort occupations in northwestern iberia? A revision of Viladonga’s site sequence, Castro de Rei, Lugo

En este artículo se presentan los principales resultados de una revisión de la secuencia del castro de Viladonga (Castro de Rei, Lugo) a partir de un análisis crono-estratigráfico del registro material, con especial relevancia de la cerámica. Este es uno de los principales yacimientos a partir del cual se ha sustentado el relato arqueológico del noroeste peninsular durante el período denominado tradicionalmente como “galaico-romano”. Importante fue la contribución historiográfica del sitio al debate sobre la continuidad de las ocupaciones fortificadas en altura durante los momentos tardíos del Imperio Romano y la época sueva, que ha generado diversas interpretaciones sobre la articulación del territorio. Estas interpretaciones partían de la idea de que este castro, y otros similares, estuvieron ocupados entre el siglo II d. C. hasta, al menos, la quinta centuria de forma ininterrumpida. Sin embargo, otras interpretaciones sugerían una cesura en esta secuencia ocupacional, si bien todavía no había sido objeto de una atención específica. La revisión crono-estratigráfica realizada en Viladonga ha permitido proponer una nueva secuencia con dos grandes fases de ocupación separadas por un hiato entre los siglos II d. C. y el V d. C. y una fase final de abandono a inicios del siglo VI d. C. La secuencia propuesta supone la reformulación de algunos de los principales paradigmas sobre las transformaciones del poblamiento en el noroeste durante este periodo.We present in this paper the main results of a revision of the chronological sequence of Viladonga (Castro de Rei, Lugo) through a chrono-stratigraphic analyses of the material culture, with special regard to pottery assembleages. This hilltop occupation has been one of most important sites through which scholars have developed an archaeological narrative of the so-called “galaic-Roman” period in the northwestern part of the Iberian Peninsula. It was particularly important for the debate around the continuity of this hilltop occupations through the post-Roman and Suevic periods, generating a diversity of interpretations on the settlement articulation in this crucial historical context. These interpretations were based on the idea that this site, and others with similar characteristics, were occupied through a long sequence between the 2nd century and 5th century AD. However, other interpretations suggested a possible break in the occupational sequence, even though they were not being specifically considered. The chrono-stratigraphic analyses of Viladonga have come to propose a new sequence with two major phases of occupation, disrupted by a hiatus between the 2nd and the fourth century and a final phase of abandonment in the 6th century AD. Consequently, this sequence implies a revision of the main paradigms on the transformation of the settlement pattern in the northwestern part of the Iberian peninsula in this period.Ministerio de Economía, Industria y Competitividad HUM2016-76094-C4-2-

Effect of an external electric field on the propagation velocity of premixed flames

There have been many experimental investigations into the ability of electric fields to enhance combustion by acting upon ion species present in flames. In this work, we examine this phenomenon using a one-dimensional model of a lean premixed flame under the influence of a longitudinal electric field. We expand upon prior two-step chain-branching reaction laminar models with reactions to model the creation and consumption of both a positively-charged radical species and free electrons. Also included are the electromotive force in the conservation equation for ion species and the electrostatic form of the Maxwell equations in order to resolve ion transport by externally applied and internally induced electric fields. The numerical solution of these equations allows us to compute changes in flame speed due to electric fields. Further, the variation of key kinetic and transport parameters modifies the electrical sensitivity of the flame. From changes in flame speed and reactant profiles we are able to gain novel, valuable insight into how and why combustion can be controlled by electric fields.This collaborative research was supported by the Spanish MCINN under Project #ENE2012–33213 and by King Abdullah University of Science and Technology (KAUST), Cooperative Agreement # 025478 entitled, electromagnetically Enhanced Combustion: Electric Flames.Publicad

The role of non-thermal electrons in flame acceleration

We examine in this work the effect of an external electric field on the propagation velocity of a laminar, one-dimensional and lean premixed flame, with the final goal of clarifying the relative importance of each of the three different mechanisms postulated in the literature to explain the effect of electric fields on flames: ionic wind, kinetic enhancement by non-thermal electrons and ohmic heating. The onedimensional model proposed here expands the four-reactions scheme previously presented by SanchezSanz, et al. (2015) to include the effect of non-thermal electrons and activated neutral molecules on flame acceleration. Two additional reactions are included in the model to complete a minimum set of six elementary reaction capable of qualitatively reproduce the results observed in classical Uaggers, and Von Engel, (1971).) and recent (Volkov et al., 2013; Murphy, et al., 2014,) experiments. The limit of weakly ionized plasmas is used to integrate the Boltzmann equation and to derive an explicit expression for the electron temperature proportional to the square of the electric field. The numerical integration of the conservation equations gives the flame propagation velocity for a given set of parameters. The results reveal the importance of the electric field polarity on flame acceleration, finding faster flames for positive electric fields than for equally intense negative fields. At low-intensity fields, our results indicate that the ionic wind, and the associated redistribution of the charged particles, is the main mechanism inducing flame acceleration. In more intense fields, the combined effect of the ionic wind and the heat transfer from the high-temperature electrons to the background gas induces a significant increase in the temperature field upstream and downstream of the flame front.This work was supported by the Spanish MCINN through projects ENE2012-33213 and ENE2015-65852-C2-1-R

Modelo local de simulación de nivel de napa freática en la Depresión del Salado

p.155-158A partir del esquema clásico del balance hidrológico seriado se elaboró un modelo que estima la variación mensual del nivel de napa freática a partir de las características físicas del suelo y de la precipitación y la evapotranspiración potencial mensuales. El modelo se ajustó tomando como referencia las series mensuales de las localidades de Dolores (1942-1977) y Chascomús (1945-1951). Pudo comprobarse que, tomando como partida los datos observados, el modelo reproduce ajustadamente el comportamiento de la napa durante 7 años, apartándose luego gradualmente. Por lo que posee capacidad para interpolar largos períodos faltantes en las series de observaciones, problema que se presenta frecuentemente con los registros de napa freática. El estudio se realizó para localidades situadas en la Depresión del Salado, lo que determina que el modelo sea de validez local ya que no se consideró el aporte de agua desde otras localidades debido a la escasa pendiente de la zona y a las características de drenaje de los suelos, las cuales determinan un movimiento vertical lento del agua debido a la presencia de horizontes de escasa permeabilidad

Cronología de inundaciones y sequías en el noreste de la provincia de Buenos Aires 1911 - 1989

p.241-249El objetivo del presente trabajo consistió en reproducir, por medio del balance hídrico del suelo, la cronología de inundaciones y sequías del Noreste de la Provincia de Buenos Aires y evaluar si la misma pudo darse dentro de un régimen de lluvias completamente aleatorio o si requirió que el mismo contuviera componentes determinísticas, como ciclos, periodicidades o saltos climáticos para producirse. Muchas de las series de datos mensuales empleadas presentaron una leve tendencia positiva, aunque en ningún caso resultó significativa debido a la alta variabilidad natural del fenómeno, que también puede ser interpretado como un salto de los promedios 1971-89 con respecto a los 1911-70, dado que tomados aisladamente ninguno de los dos períodos presenta tendencia. El análisis espectral reveló algunos picos levemente significativos y cuasi significativos, pero con una contribución muy pequeña a la variancia total, lo que hace descartar los efectos de procesos periódicos o cuasi periódicos. El estudio de rachas reveló que las de precipitación son completamente aleatorias y ráramente exceden los tres meses de duración, mientras que las de humedad del suelo muestran un proceso markoviano con alta persistencia pudiendo llegar a los 18 meses de extensión. Comparado con el período 1911 -70, el período 1971 -89 presentó un predominio de las rachas húmedas

Population pharmacokinetics and pharmacokinetic/pharmacodynamic evaluation of marbofloxacin against Coagulase-negative staphylococci, Staphylococcus aureus and Mycoplasma agalactiae pathogens in goats

Marbofloxacin is a broad-spectrum fluoroquinolone, and an extra-label use has been reported in horse, sheep and goat. However, extrapolation of dosage regimens from cattle to horse and small ruminants could lead to incorrect dosing due to pharmacokinetic differences among species, increasing the risk of antimicrobial resistance or toxicity. Pharmacokinetic properties of marbofloxacin, including PK/PD analysis, have been studied by intravenous, intramuscular and subcutaneous administration in lactating and non-lactating goats. A population pharmacokinetic model of marbofloxacin in goats was built using 10 pharmacokinetic studies after intravenous, intramuscular, and subcutaneous administration at a dose of 2, 5 and 10 mg/kg. Serum or plasma and milk concentration-time profiles were simultaneously fitted with a non-linear mixed effect model with Monolix software. Level of milk production (lactating and non-lactating) and health status (healthy and un-healthy) were retained as covariates on volume of distribution and clearance. Marbofloxacin concentrations were well described in plasma/serum and milk by the population model. Simulated dose regimens of marbofloxacin administered at 2, 5 and 10 mg/kg by intramuscular route for five days were evaluated (n = 5000 per group). Steady-state fAUCs for each dose regimen were obtained. Probability of target attainment of fAUC/MIC ratios were determined and PK/PDco values (highest MIC for which 90% of individuals can achieve a prior numerical value of the fAUC/MIC index) were established using Monte Carlo simulations (n = 50,000). MIC values for wild type isolates of Staphylococcus aureus, coagulase negative staphylococci, and Mycoplasma agalactiae were determined and tentative epidemiological cutoff (TECOFF) were obtained at 1.0, 0.5 and 0.5 mg/L, respectively. The PK/PDco for the dose regimen of 2 mg/kg/24 h and 5 mg/kg/24 h (0.125 and 0.25 mg/L) were lower than TECOFF (0.5 and 1 mg/L). The dosage regimen of 10 mg/kg/24 h was adequate for intermediate MIC values of 0.125–0.50 mg/L and could be effective for a population with a target fAUC/MIC ratio ˂ 48 for Coagulase negative staphylococci and Mycoplasma agalactiae, but not for Staphylococcus aureus. Results obtained in thi

Comparative study of two cogeneration systems based on energy recovery of fumes from a casting process

This paper develops the comparison of two cogeneration systems that are suitable to perform heat energy recovery of the smoke produced by a casting process.The authors would like to thank the financial support of Government of Cantabria and NISSAN under the INVESNOVA research project and to the Council on Research and Technological Development of the University of Cantabria by their administrative assistance

Basicoanimal

En muchos escritos, películas y libros (de los cuales se hablará más adelante) se ha mostrado el lado animal del hombre, como su lado maligno, atrevido e impulsivo, pero no se puede desconocer que ese animal que llevamos dentro también es un animal lleno de amor, de sentimientos filiales, de ternura. Esta obra intenta honrar, apreciar y enaltecer todos los estados animales en el ser humano. Es un homenaje al hombre en su básico animal, al animal honesto, al animal interno, expresando sus sentimientos de rabia, dolor, cansancio, amor, ternura, felicidad sin ninguna reserva.Maestro (a) en Artes VisualesPregrad