Auto-ignition Modeling in a Spark Ignition Internal Combustion Engine Fueled with Gaseous Fuels with Variable Methane Number

A semi-empirical model for determining Knock Occurrence Crank Angle (KOCA) in a Cooperative Fuel Research (CFR) engine was developed. The model is based on the Integral Model approach and experimental data collected in a factorial 23 with axial and central runs experiment. Mixtures of CH4/H2 were employed as fuel. The model was accurate enough to predict KOCA with a maximum and minimum error of just 3.6 and 0.9 degrees respectively. To study the auto-ignition chemistry and its relationship with the knock resistance of gaseous fuels, the Methane Number of CO/CO2/H2 mixtures were measured. A correlation for estimating Methane Number as a function of fuel compositions was proposed. The proposed correlation is a good tool for estimating the Methane Number of fuels with high concentration of carbon dioxide, carbon monoxide and hydrogen. A comprehensive evaluation of the accuracy of a detailed chemical kinetics mechanism for predicting KOCA in a CFR engine was carried out. The spark ignition engine model of Chemkin Pro® software coupled with Gri-Mech. 3.0 chemical kinetics mechanism was used to model auto-ignition A set of equations for calculating residual gas fraction (x_r), inlet valve close gas temperature (T_IVC) and residual gas temperature?(T?_r) were proposed. Moreover, a technique for estimating combustion parameters from the indicator diagram was developed. Results reveal that accuracy of the mechanism used for estimating KOCA decreases as compression ratio decreases. This result is consistent with the lack of accuracy of the mechanism for predicting ignition delay time of gaseous fuel at low temperature

Ponderación ML de parámetros en un sistema de reconocimiento de palabras basado en CDHMM

Speech dynamic feature are routinely used in current speech recognition systems in combination with short-term (static) spectral features. The aim of this paper is to propose a method to automatically estimate the optimum ponderation of static and dynamic features in a speech recognition system. The recognition system considered in this paper is based on Continuous-Density Hidden Markov Modelling (CDHMM) widely used in speech recognition. Our approach consists basically in 1) adding two new parameters for each state of each model that weight both kinds of speech features, and 2) estimating those parameters by means of a Maximum Likelihood training. Experimental results in speaker independent digit recognition show an important increase of recognition accuracy.Peer ReviewedPostprint (published version

Innovative concepts of Integrated Solar Combined Cycles (ISCC) using a Solid Oxide Fuel Cell (SOFC)

Concentrating Solar Power (CSP) is one of the most promising ways for electricity production of the upcoming years with high penetration of intermittent renewable energy sources such as wind and solar-photovoltaics. This is due to the fact that CSP when coupled to Thermal Energy Storage (TES) system enables large, inexpensive and flexible energy dispatch, which contributes to energy grid stabilization. At the same time, TES allows for steady operation of the power block by reducing undesirable fluctuations due to weather transient conditions and increasing the number of hours that the power block operates at design conditions 1. Despite the abovementioned advantages of CSP systems, a step further is needed for increase overall system efficiency and decrease CO2 emissions. Several studies have been performed considering high efficiency plant layouts such as combined cycle. For the latter, several works have been investigated about solar integration of combined cycle using parabolic trough and solar tower technologies. In both cases, solar energy was used for water/steam preheating and evaporation steps of the Rankine cycle in combination with the exhaust gases of fossil-fuel gas turbine engine. However, no research has been performed considering ISCC coupled with a Solid Oxide Fuel Cell (SOFC). In this research, two innovative layouts of ISCC power plants will be analyzed. First considers a ISCC based on solar tower and second a ISCC with a parabolic trough collector field coupled to the Heat Recovery Steam Generator (HRSG). The objective of this research is analyze the energy behavior of both layouts, selecting the best ISCC scheme to be coupled with a SOFC. The simulations will be performed using Thermoflex software. In both layouts, a SOFC is introduced before the combustion chamber at the topping cycle, and a Rankine cycle (bottoming cycle) with 2 pressures is considered.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Selección de plantas superiores de banano Gros Michel (AAA) en asocio caféárboles en cuatro fincas de la comunidad Yasica Sur San Ramón, Matagalpa, II semestre del año 2013

La presente investigación se realizó en la comunidad de Yasica Sur- municipio San Ramón Matagalpa durante el año 2013-2014, la muestra se constituyó con cuatro productores que poseen asocio de bananos, café y árboles forestales. Evaluándose como variables: Principales características que se deben tomar en cuenta para la selección de plantas superiores, tipos de propagación usada por los productores, altura sobre el nivel del mar (asnm). El propósito de la presente investigación fue identificar plantas superiores de banano Gros Michel (AAA) para mejorar la producción en la comunidad de Yasica Sur- San Ramón, Matagalpa, en el II semestre 2013. El tipo de estudio empleado es de carácter descriptivo cualicuantitativo porque se cuantificó y calificó las principales características físicas y productivas de las plantas de banano Gros Michel (AAA), Número de plantas, Altura de la planta (cm), grosor del pseudotallo (cm), % de sombra, Número de hojas, Anclaje, Tamaño del racimo (cm), Peso del racimo (kg), Número de manos por racimo, Número dedos por mano, grosor y largo de los dedos (cm), concluyendo con la validación de la hipótesis general debido que han mejorado las plantaciones de banano con plantas que presentan mejores características fisiológicas y productivas, se incrementará la producción de banano en la comunidad. Se lograron identificar 69 plantas de las cuales 40 fueron del productor Marvin Ochoa donde se encontró 4 plantas superiores, 17 para el productor Lorenzo Granado con 2 plantas superiores, 5 para el productor Milton Palacios donde se encontró 2 plantas superiores y el productor René Tinoco con 7 plantas muestreadas no se encontró plantas superiore

Visual Disability and Causes of Preventable Blindness

The World Health Organization (WHO) estimates, worldwide, approximately 1300 million people with a form of visual impairment. More than 314 million have a severe visual impairment. Of these, 37 million are blind and 124 million suffer from low vision. Eighty percent of all these cases are considered avoidable. The main causes of blindness from one country to another, in order of frequency, are cataract (39%), uncorrected refractive errors (18%), and glaucoma (10%). In Latin America and the Caribbean, the loss of vision in adults continues to be a public health problem. Blindness and visual impairment tombs have a remarkable impact on the socioeconomic development of individuals and societies and the prevention of avoidable visual disabilities in the long term in terms of attention to health care and social expenditures. Of all the organs of the body, the eye is more accessible to direct examination. The visual function can be evaluated by means of simple subjective tests. The same can be taken care of from an adequate primary care service

Determinantes Sociales de la Salud identificados en la aparición de malaria en el área urbana de la ciudad de Bilwi. Municipio de Puerto Cabezas, RACCN de Nicaragua 2014-2016

Estudio descriptivo de corte transversal realizado en el área urbana del municipio del Puerto Cabezas, el universo fue la población urbana de la ciudad de Bilwi afectada con malaria y la muestra compuesta por 65 personas escogidas por método no probabilístico en bolas de nieve, la unidad de análisis fueron las personas diagnosticadas con malaria del área urbana de la ciudad de Bilwi. El 90.8% de los entrevistados fueron misquitos, El 100% de las personas residían en los barrios de Bilwi, el 100% de los encuestados tenía más de 1 a 3 años de vivir en el barrio, un 72.3% la Malaria fue causada por la suciedad, un 83.1% de las viviendas la basura la quemaban y el 6.2% la depositan en el tren de aseo, el métodos de protección contra el vector y el más usado fue el mosquitero en el 100% de las viviendas, en el 52.3% la casa y sus alrededores estaba sucia, el 75.4% de las viviendas se les realizó la Respuesta al caso de estas el 63.1% fueron visitadas en los primeros 5 días posterior al diagnóstico, el 9.2% fue visitadas a la semana, el resto en un tiempo mayor, 67.7% se les brindó todas las actividades integrales, el clima referido por los encuestados, la temperatura en el 76.9% es alta, la humedad el 86.2% es media, la fuerza de los vientos el 60% es media, y la pluviosidad el 72.3% llueve diario, la intensidad de las lluvias el 49.2% refirieron que es moderada. Las condiciones climatológicas, la falta de Higiene tanto del medio ambiente como domiciliar en el área urbana (intra y peri domiciliar), el no contar con los servicios básicos indispensables, las acciones en el tiempo correspondiente a la norma del programa de control de vectores, el análisis de previsión con la información que se cuenta, la pobreza extrema, la falta de coordinación interinstitucional para solucionar el problema de la basura, fueron entre los principales determinantes sociales y de salud identificados durante el estudi

Aproximación a los modelos de responsabilidad penal de las personas jurídicas

En la presente monografía se pretende hacer una descripción de los diferentes modelos propuestos para atribuir responsabilidad penal a las personas jurídicas. Entre estos modelos se encuentran los que proponen sistemas de autorresponsabilidad, es decir, teniendo en cuenta únicamente las actuaciones de la propia empresa. De otra parte, se hace referencia al modelo de heterorresponsabilidad, en el cual se tiene en cuenta las actuaciones de las personas físicas que actúan a nombre de la empresa. Se hace además una breve referencia al modelo alemán, el cual no consagra sanciones penales, sino de carácter administrativo. Finalmente se hace referencia a la situación actual de la responsabilidad penal de personas jurídicas en Colombia

A Case-Based Reasoning Model Powered by Deep Learning for Radiology Report Recommendation

Case-Based Reasoning models are one of the most used reasoning paradigms in expert-knowledge-driven areas. One of the most prominent fields of use of these systems is the medical sector, where explainable models are required. However, these models are considerably reliant on user input and the introduction of relevant curated data. Deep learning approaches offer an analogous solution, where user input is not required. This paper proposes a hybrid Case-Based Reasoning, Deep Learning framework for medical-related applications, focusing on the generation of medical reports. The proposal combines the explainability and user-focused approach of case-based reasoning models with the deep learning techniques performance. Moreover, the framework is fully modular to fit a wide variety of tasks and data, such as real-time sensor captured data, images, or text, to name a few. An implementation of the proposed framework focusing on radiology report generation assistance is provided. This implementation is used to evaluate the proposal, showing that it can provide meaningful and accurate corrections, even when the amount of information available is minimal. Additional tests on the optimization degree of the case base are also performed, evidencing how the proposed framework can optimize this base to achieve optimal performance

Value of Travel Time Savings for University Students and Preference Heterogeneity

This paper examines the sensitivity of value of travel time savings (VTTS) to assumptions on individual preferences in a random utility discrete choice framework. Preferences heterogeneity is incorporated by introducing random parameters and by interacting characteristics of travel modes with characteristics of the individual. The data set is a revealed preference survey on student travel mode choice. The results indicate that there is a systematic influence of gender on VTTS and additional heterogeneity is explained by unobserved characteristics. The evidence also suggests model specifications that impose preferences homogeneity tend to produce lower estimates of VTTS compared with more flexible structures that allow random variation of parameters over individuals. However, the degree of underestimation seems to be context dependent..Random utility discrete choice models, preference heterogeneity, subjective value of travel time, random parameter logit.