Instalación experimental para la investigación de motores de combustión interna con hidrógeno

El desarrollo de motores de combustión interna (MCI) más eficientes, alimentados con combustibles potencialmente limpios como el hidrógeno, se presenta como una posible solución a las problemáticas ocasionadas por las emisiones de gases contaminantes y de efecto invernadero generadas por las unidades de potencia convencionales. Sin embargo, para optimizar el diseño de los motores, es necesario profundizar los conocimientos sobre los procesos de transferencia de calor, combustión y turbulencia involucrados en la propagación de llamas premezcladas de aire/hidrógeno. El uso de este último habilita el funcionamiento del MCI con mezcla pobres, esto habilita modificaciones que permitirían mejorar la eficiencia del sistema e inhibir la producción de los distintos óxidos de nitrógeno, debido a la baja temperatura de combustión. En este trabajo se presenta la metodología experimental utilizada para investigar los procesos de flujo y transferencia de calor en un MCI alimentado con hidrógeno. Dicha experimentación, a su vez, busca ser utilizada para desarrollar y validar modelos de mecánica de fluidos computacional que permitan dar cuenta de los sendos fenómenos que ocurren en simultáneo en la cámara de combustión. Se detallan los aspectos operativos de la instalación, el sistema de control, la instrumentación y el método experimental. Finalmente se muestran resultados del relevamiento de la geometría interna del motor, la flujometría de la admisión y curvas preliminares de presión en el circuito admisión y la cámara de combustión.Eje: Combustibles tradicionales y alternativos.Facultad de Ingenierí

Instalación experimental para la investigación de motores de combustión interna con hidrógeno

El desarrollo de motores de combustión interna (MCI) más eficientes, alimentados con combustibles potencialmente limpios como el hidrógeno, se presenta como una posible solución a las problemáticas ocasionadas por las emisiones de gases contaminantes y de efecto invernadero generadas por las unidades de potencia convencionales. Sin embargo, para optimizar el diseño de los motores, es necesario profundizar los conocimientos sobre los procesos de transferencia de calor, combustión y turbulencia involucrados en la propagación de llamas premezcladas de aire/hidrógeno. El uso de este último habilita el funcionamiento del MCI con mezcla pobres, esto habilita modificaciones que permitirían mejorar la eficiencia del sistema e inhibir la producción de los distintos óxidos de nitrógeno, debido a la baja temperatura de combustión. En este trabajo se presenta la metodología experimental utilizada para investigar los procesos de flujo y transferencia de calor en un MCI alimentado con hidrógeno. Dicha experimentación, a su vez, busca ser utilizada para desarrollar y validar modelos de mecánica de fluidos computacional que permitan dar cuenta de los sendos fenómenos que ocurren en simultáneo en la cámara de combustión. Se detallan los aspectos operativos de la instalación, el sistema de control, la instrumentación y el método experimental. Finalmente se muestran resultados del relevamiento de la geometría interna del motor, la flujometría de la admisión y curvas preliminares de presión en el circuito admisión y la cámara de combustión.Eje: Combustibles tradicionales y alternativos.Facultad de Ingenierí

Instalación experimental para la investigación de motores de combustión interna con hidrógeno

El desarrollo de motores de combustión interna (MCI) más eficientes, alimentados con combustibles potencialmente limpios como el hidrógeno, se presenta como una posible solución a las problemáticas ocasionadas por las emisiones de gases contaminantes y de efecto invernadero generadas por las unidades de potencia convencionales. Sin embargo, para optimizar el diseño de los motores, es necesario profundizar los conocimientos sobre los procesos de transferencia de calor, combustión y turbulencia involucrados en la propagación de llamas premezcladas de aire/hidrógeno. El uso de este último habilita el funcionamiento del MCI con mezcla pobres, esto habilita modificaciones que permitirían mejorar la eficiencia del sistema e inhibir la producción de los distintos óxidos de nitrógeno, debido a la baja temperatura de combustión. En este trabajo se presenta la metodología experimental utilizada para investigar los procesos de flujo y transferencia de calor en un MCI alimentado con hidrógeno. Dicha experimentación, a su vez, busca ser utilizada para desarrollar y validar modelos de mecánica de fluidos computacional que permitan dar cuenta de los sendos fenómenos que ocurren en simultáneo en la cámara de combustión. Se detallan los aspectos operativos de la instalación, el sistema de control, la instrumentación y el método experimental. Finalmente se muestran resultados del relevamiento de la geometría interna del motor, la flujometría de la admisión y curvas preliminares de presión en el circuito admisión y la cámara de combustión.Eje: Combustibles tradicionales y alternativos.Facultad de Ingenierí

Validation and Enhancement of a Supermesh Strategy for the CFD Simulation of Four-Stroke Internal Combustion Engines

The present paper describes and validates an efficient CFD implementation to replicate the working fluid-dynamics of a real four-stroke internal combustion engine. To do this, experimental data obtained on a single-cylinder engine are used to validate the proposed computational approach. The engine domain is divided into regions according to each moving zone, and these are coupled using a pseudo-supermesh interface presented in a previous work by the authors. In this work, the original pseudo-supermesh strategy is enhanced by introducing the dual-boundary concept to model the valve opening/closing events to increase the accuracy and simplicity of the simulation procedure. The results produced by the proposed software tool show a good correlation to the experimental measurements of the complete engine cycle. Macroscopic quantities of the in-cylinder flow are accurately replicated as well as the instantaneous evolution of the in-cylinder and intake manifold pressure. Furthermore, the present work shows that the computational efficiency and scalability of the enhanced pseudo-supermesh approach are preserved even when applied to more complex real problems. In this sense, this work contributes to a new engineering tool promoting the enhanced pseudo-supermeshes as an effective tool for the design, development, and optimization of internal combustion engines.Fil: Aguerre, Horacio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Pedreira, Patricio Hernán. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Orbaiz, Pedro Jose. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Nigro, Norberto Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentin

Desarrollo del modelo aerodinámico de un cohete supersónico

Este trabajo presenta el diseño aerodinámico del cohete Theros III, que participó en la competencia Spaceport America Cup. Las estructuras aerodinámicas fueron diseñadas en base a información de la literatura y corregidas con datos del simulador OpenRocket en un proceso iterativo que incluyó el diseño y selección del motor del lanzador. La telemetría obtenida en vuelo permitió concluir que las estimaciones del coeficiente de arrastre del lanzador, realizadas con OpenRocket empleando el método de Barrowman, fueron en exceso. La implementación de un modelo de mecánica de fluidos computacional permitió obtener coeficientes de arrastre menores a los previstos por OpenRocket y similares a los estimados por Aerolab, simulador que emplea datos experimentales para sus predicciones.Facultad de Ingenierí

Characterization of individuals at high risk of developing melanoma in Latin America: bases for genetic counseling in melanoma

PURPOSE: CDKN2A is the main high-risk melanoma-susceptibility gene, but it has been poorly assessed in Latin America. We sought to analyze CDKN2A and MC1R in patients from Latin America with familial and sporadic multiple primary melanoma (SMP) and compare the data with those for patients from Spain to establish bases for melanoma genetic counseling in Latin America. METHODS: CDKN2A and MC1R were sequenced in 186 Latin American patients from Argentina, Brazil, Chile, Mexico, and Uruguay, and in 904 Spanish patients. Clinical and phenotypic data were obtained. RESULTS: Overall, 24 and 14% of melanoma-prone families in Latin America and Spain, respectively, had mutations in CDKN2A. Latin American families had CDKN2A mutations more frequently (P = 0.014) than Spanish ones. Of patients with SMP, 10% of those from Latin America and 8.5% of those from Spain had mutations in CDKN2A (P = 0.623). The most recurrent CDKN2A mutations were c.-34G>T and p.G101W. Latin American patients had fairer hair (P = 0.016) and skin (P < 0.001) and a higher prevalence of MC1R variants (P = 0.003) compared with Spanish patients. CONCLUSION: The inclusion criteria for genetic counseling of melanoma in Latin America may be the same criteria used in Spain, as suggested in areas with low to medium incidence, SMP with at least two melanomas, or families with at least two cases among first- or second-degree relatives.Genet Med 18 7, 727-736

Eligibility criteria for Menopausal Hormone Therapy (MHT): a position statement from a consortium of scientific societies for the use of MHT in women with medical conditions. MHT Eligibility Criteria Group

This project aims to develop eligibility criteria for menopausal hormone therapy (MHT). The tool should be similar to those already established for contraception A consortium of scientific societies coordinated by the Spanish Menopause Society met to formulate recommendations for the use of MHT by women with medical conditions based on the best available evidence. The project was developed in two phases. As a first step, we conducted 14 systematic reviews and 32 metanalyses on the safety of MHT (in nine areas: age, time of menopause onset, treatment duration, women with thrombotic risk, women with a personal history of cardiovascular disease, women with metabolic syndrome, women with gastrointestinal diseases, survivors of breast cancer or of other cancers, and women who smoke) and on the most relevant pharmacological interactions with MHT. These systematic reviews and metanalyses helped inform a structured process in which a panel of experts defined the eligibility criteria according to a specific framework, which facilitated the discussion and development process. To unify the proposal, the following eligibility criteria have been defined in accordance with the WHO international nomenclature for the different alternatives for MHT (category 1, no restriction on the use of MHT; category 2, the benefits outweigh the risks; category 3, the risks generally outweigh the benefits; category 4, MHT should not be used). Quality was classified as high, moderate, low or very low, based on several factors (including risk of bias, inaccuracy, inconsistency, lack of directionality and publication bias). When no direct evidence was identified, but plausibility, clinical experience or indirect evidence were available, "Expert opinion" was categorized. For the first time, a set of eligibility criteria, based on clinical evidence and developed according to the most rigorous methodological tools, has been defined. This will provide health professionals with a powerful decision-making tool that can be used to manage menopausal symptoms

Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study an international prospective cohort study

We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care. We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care