Resumen. En esta investigación se analizó la influencia de diferentes estructuras obtenidas en el proceso de recocido para la vida útil de los elementos finales (baleros). Se observó, con base en los resultados, que existe una estrecha relación entre las estructuras (tamaño de carburos) en estado recocido y las propiedades mecánicas de elementos finales después del temple y revenido.

This study compares the energy efficiency of two processes covering the thermal energy demand of a swimming pool: a combined heat and power (CHP) unit on the one hand, and a heat pump with internal combustion engine on the other hand. The thermal energy demand of the swimming pool was 1438 kWh per day (78% heating the pool and 22% providing hot water for showers), owing to temperate climate in the city of Toluca in central Mexico; a mean annual temperature of 13.5 °C (10.5 °C in January and 15.7 °C in June) offers a large potential of renewable thermal energy stored in the atmosphere. Its utilization in heat pumps driven by thermal combustion engines can provide energy below 60 °C; this temperature level provides hot water for showers while a lower temperature level of about 40°C heats up the pool water and swimming hall. Depending on outdoor temperature, which defines the load for the units, the efficiency in terms of total primary energy consumption is better for the CHP solution (100% and 80% load) and is better for the heat pump in the case of a 57% load. The energy losses for the CHP unit on-site are equivalent to half the losses caused by extraction and distribution of natural gas under current circumstances in Mexico. The results provide a decision tool.

Recently, throughout the world, there is a special emphasis on the development of a photovoltaic industry. In fact, the solar photovoltaic (PV) is now, after hydro and wind power, the third most important renewable energy source in terms of globally installed capacity. The growth rate of the PV industry during 2011 increased by almost 70 percent, an outstanding level among all renewable technologies. Especially in Mexico, there is great potential for this kind of systems. In July 2007 the CRE (Energy regulation commission) published the grid connection contract. This contract opens the possibility of installing small solar PV systems connected to the grid (up to 10 kWp for residential applications and 30 kWp for industrial applications). This allowed for an important growth of the photovoltaic industry. Due to that important development of the PV industry, there is a need for engineers trained to design, install, and evaluate this kind of systems. The Autonomous University of the State of Mexico (UAEMEX) offers a new engineering program related to the development of sustainable energy systems. This kind of engineering program requires special equipment for experimentation and practice. Part of this equipment is very expensive and is designed just for certain applications. Specialists at UAEMEX detected the need of a system to evaluate and demonstrate the application of PV modules, but they also found that most of the systems in the market are too small and are not capable of evaluating different arrangements. This paper sets forth the design of a mobile system to evaluate PV modules and arrangements. This system is useful, not only for demonstration practices, but also for experimentation with different materials and types of PV cells. The design allows the completion of 2 or 4 PV modules with different positions and inclination. Also, it is prepared to simulate some interferences and shadows on the modules in order to evaluate their effect. The prototype is equipment with a data acquisition system that will be used to obtain the PV module curves. Also, it will be used to evaluate the atmospheric and shadow effects on these modules. This prototype will be used to complement the learning of solar-PV systems, but also to meet the needs of basic science, math, and engineering teaching objectives in an integrated and hands-on way. A basic description of the design of the system proposed is set forth in this paper with a comparative analysis of the systems in the market. Finally, there is a summary of practices that may be performed with the equipment proposed.

En este trabajo se realiza un análisis de la forma en la cual la situación económica, tecnológica y medioambiental actual genera la necesidad de nuevos profesionales capaces de resolver las problemáticas actuales. Se hace especial énfasis en el aspecto ambiental y energético para establecer la responsabilidad actual de la Ingeniería en el consumo de energía, tanto a nivel nacional como mundial, y la necesidad de un especialista en sistemas energéticos cuyo papel sea el diseñar sistemas que permitan emplear la energía de manera eficiente y sustentable. Con base en ello se indican al final algunas competencias que este profesional debe desarrollar durante su formación. Palabras Clave: Contexto energético, sistemas energéticos sustentables.

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Background: The increase in life expectancy has led to the performance of major hepatectomies in elderly patients more frequently.The objective is to present surgical results in patients older than 80 years undergoing a major hepatectomy and to make a comparison with the group under 80 years in our institution. Methods: A non-concurrent cohort study of patients older than 80 years who underwent a major hepatectomy at Hospital Clinico of Universidad Catolica from January 2006 to July 2017. Database designed in ExcelÒ 14.4 for analysis of biodemographic, clinical and morbimortality data. Results: Eight patients were analyzed. Mean age 82.6 AE 2.2 years. Six patients (75%) male. The most frequent surgical indication was intrahepatic cholangiocarcinoma and hiliar cholangiocarcinoma in two patients each one (25%). Four patients (50%) underwent right (RH) and 4 (50%) a left hepatectomy (LH). Morbidity was present in 3 patients (37.5%) with Clavien-Dindo ! IIIa only in 1 patient (12.5%) submitted to LH required reoperation by biliperitoneum. Mean operative time was 360 AE 158 and 240 AE 0 min for RH and LH respectively. Comparing the morbidity among the group younger than 80 years in relation to the older than 80 years group in LH, the clinically relevant morbidity (Clavien-Dindo ! IIIa) was significantly lower in the latter. The mean of hospitalization days was 24 AE 22 days for RH group and 7 AE 2 days for LH group showing no statistically difference. There was no perioperative mortality or at 30 days after surgery. Conclusion: These group of patients does not present greater morbidity and mortality than patients under 80 years operated in our institution.

Las ciudades además de ser centros de interacción social y económica, tienen unos atributos urbanos y arquitectónicos inherentes que las hacen atractivas para la concentración de personas y actividades económicas diversas. En este artículo se estudia para la Región Metropolitana de Barcelona cómo la proximidad física a los centros urbanos de mayor jerarquía constituye un elemento determinante para el crecimiento del empleo en los sectores económicos intensivos en conocimiento. Se estudian por ello los factores que están explicando la densidad y los cambios en la concentración del empleo en el periodo 1991-2001 en las áreas de funcionalidad económica de la Región. Los resultados muestran que es fundamentalmente la distancia al centro metropolitano el factor determinante del crecimiento de estos sectores económicos por los beneficios que la aglomeración y la proximidad geográfica tienen para su desempeño.

CIES2020: As Energias Renováveis na Transição Energética: Livro de Comunicações do XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia Solar. Helder Gonçalves, Manuel Romero (Ed.). Lisboa, Portugal: LNEG, 3-5 Novembro, 2020, p. 131-136. ISBN: 978-989-675-076-3

Compound parabolic concentrators (CPCs), whose origin dates back to the mid-1960s, gave rise to anidolic optics. Systems of this type allow the thermodynamic limit of solar concentration to be reached; however, in the case of CPCs, they involve systems with a very large height in relation to the aperture area (svelteness). Thus, arbitrary criteria have been proposed to reduce the height of the systems (truncation) and to be able to give them a real application. These truncation criteria establish the elimination of the upper part of the CPCs at a certain height in order to considerably reduce the height, but this has certainly undesirable consequences, since the geometric concentration (ratio of aperture area to receiver area) decreases with respect to the original design, which can limit the operating temperatures. Alternatively, a geometrical criterion has been proposed to truncate the CPCs without losing geometrical concentration, and still manage to reduce the height of the system by approximately 30%. This criterion consists of avoiding that the parabolic section mirrors do not block the incident rays that enter the aperture area with the maximum acceptance angle, thus defining an optimum truncation angle of 3 times the acceptance angle. However, now, with the help of the constructal law, it is possible to demonstrate that this angle is the optimum from a geometric viewpoint. Additionally, a new dimensionless number is defined for solar concentrating systems, relating the entropy generation distribution ratio, allowing to demonstrate that the Rincón criterion is the optimum for C g > 2.28.

El proceso de destilación de mezcal en México, data del siglo XVIII [1] y hasta la fecha se siguen empleando fuentes no renovables de energía para su producción. Por lo cual en este trabajo se expone el diseño de un destilador solar para que por medio de agua calentada a través de concentradores solares parabólicos (CPC´s) y haciéndola pasar por una espiral de cobre satisfaga los requerimientos de potencia y temperatura para un proceso óptimo de destilación y evitar con esto el uso de fuentes no renovables de energía y un compuesto no deseado en la elaboración del mezcal, tal como las puntas las cuales se obtienen cuando el calentamiento rebasa la temperatura de 90° C (esta temperatura se obtiene cuando el proceso se realiza de manera artesanal y no hay un control de la misma) Como resultado a través de ecuaciones, gráficas y simulaciones realizadas por medio del software SolidWorks, se obtuvo que con este tipo de cambio es posible dejar atrás un proceso que lleva aproximadamente II...

En los años recientes, el uso de la energía solar en diversos procesos ha mostrado ser una alternativa viable en relación a opciones tradicionales basadas en fuentes convencionales. En el caso de la ingeniería en alimentos, las tecnologías solares permiten obtener productos de alta calidad nutritiva a un bajo costo. La deshidratación es uno de los procesos más antiguos de preservación de alimentos, el cual consiste en retirar el agua del producto sin alterar su composición y debido a la mínima cantidad de este elemento vital, los microorganismos no se desarrollan y quedan detenidas la mayoría de las reacciones químicas y enzimáticas de alteración, manteniendo sus características nutritivas y aumentado la vida media del mismo; impidiendo con esto que la fruta se pudra y se desperdicie.