Estudio de la transferencia de calor conjugada en canales inclinados con calentamiento asimétrico

La transferencia de calor juega un papel importante ya que no sólo se encuentra presente en la naturaleza, sino que también se hace presente en la mayoría de los procesos industriales y en áreas vitales como la producción y conversión de energía. La trasferencia de calor, a través de cualquiera de los mecanismos de transferencia de calor conducción, convección y radiación, está involucrada en las oportunidades de ahorro energético

EXPERIMENTS SIMULATION AND DESIGN TO SET TRAFFIC LIGHTS’ OPERATION RULES

[EN] In this paper it is used the experimental design to minimize the travel time of motor vehicles, in one of the most important avenues of Celaya City in Guanajuato, Mexico, by means of optimal synchronization of existing traffic lights. In the optimization process three factors are considered: the traffic lights’ cycle times, the synchrony defined as stepped, parallel and actual, and speed limit, each one with 3 evaluation levels. The response variables to consider are: motor vehicles’ travel time, fuel consumption and greenhouse effect gas (CO2) emissions. The different experiments are performed using the simulation model developed in the PTV-VISSIM software, which represents the vehicle traffic system. The obtained results for the different proposed scenarios allow to find proper levels at which the vehicle traffic system must be operated in order to improve mobility, to reduce contamination rates and decrease the fuel consumption for the different motor vehicles that use the avenue.Espinoza Mondragón, J.; Jimenez García, J.; Medina Flores, JM.; Vázquez López, JA.; Téllez Vázquez, S. (2016). EXPERIMENTS SIMULATION AND DESIGN TO SET TRAFFIC LIGHTS’ OPERATION RULES. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 907-919. https://doi.org/10.4995/CIT2016.2015.4093OCS90791

Regeneración natural y plantaciones de especies forestales, como dos métodos restauración pasiva y activa en un fragmento de bosque en la Mina San Albino, Nueva Segovia

El presente trabajo de investigación se llevó a cabo en cuatro parcelas permanentes de muestreo (PPM) de 25 m x 25 m y cinco ensayos de nucleación, como dos métodos de restauración ecológica, pasiva y activa respectivamente, en un fragmento de bosque de la Mina San Albino en el departamento de Nueva Segovia. El objetivo del estudio es generar información sobre la dinámica poblacional y crecimiento de las especies en las PPM durante un año y la sobrevivencia, crecimiento de ocho especies arbóreas: Lysiloma divaricatum, (Jacq.) J.F. Macbr. Tabebuia chrysantha (Jacq.) Nicholson, Enterolobium, cyclocarpum (Jacq.) Griseb. Brosimum alicastrum Swartz. Tabebuia rosea (Bertol.) DC, Hymenaea courbaril L, Cedrela odorata L y Calycophyllum candidissimum (Vahl) DC. Utilizadas en el ensayo de nucleación durante un periodo de seis meses. En las PPM la vegetación fue clasificada en Fustal, Latizal y Brinzal. En la categoría de fustal durante el año de estudio se registraron cambios en términos de número de especies y abundancia, se determinaron 5 especies y 14 individuos en 0.25 ha para el año 2019 y para el siguiente se determinaron 6 especies y 16 individuos. El incremento corriente anual (ICA) en diámetro fue de 1.7 cm /año. En la categoría de latizal, el número de especies se incrementó de 10 a 13. Igualmente, el número de individuos aumento de 30 individuos hasta 38. Durante el año evaluado desaparecieron o murieron 2 individuos lo que representa una tasa de mortalidad anual de 6.9 %. Así mismo, un total de 10 nuevos individuos fueron registrado, estimándose una tasa de reclutamiento del 30.5 %. El incremento corriente anual (ICA) en diámetro fue de 1.2 cm/año. En la categoría de Brinzal para el año 2019 se registraron 104 individuos y en el (2020) 164 individuos. En el ensayo de nucleación la sobrevivencia de los individuos de seis especies superó el 90%. Solamente el T. rosea Falso Roble y C. odorata Cedro real registraron sobrevivencias de 50 y 70% respectivamente. El incremento en diámetro durante los seis meses evaluados para las 8 especies fue de 2.2 mm. El mayor incremento lo registro la especie, B.alicastrum (Ojoche) con 2.6 mm y el menor el H. courbaril Guapinol con 2.2 mm. El incremento en altura promedio para todas las especies fue de 25.75 cm, siendo el E. cyclocarpum (Guanacaste Negro) el que registro mayor incremento con 34.8 cm y el Ojoche el menor con 10.7 cm

Influence of Stress Assessed through Infrared Thermography and Environmental Parameters on the Performance of Fattening Rabbits

Rabbits often experience stress when they perceive certain stimuli, such as handling. The physiological response of animals to stress and temperament is associated with feeding efficiency, with those with the least capacity to react to stress showing the highest performance. The aim of this study was to evaluate the impact of stress due to heat (temperature-humidity index; THI) or handling, assessed using infrared thermography, on the performance parameters of rabbits of a Spanish Common breed. Thirty-nine rabbits were analyzed during a 38-d fattening period at two times of the year: a cold period and a warm period. The rabbits’ stress due to handling was assessed by the temperature difference taken in the inner ear, before and after being handled. The animals were more productive in the cold season. Temperature-humidity index significantly influenced average daily gain (ADG) and daily feed intake (DFI). Rabbits with higher levels of stress showed higher ADG, DFI and feed conversion ratio (FCR) values. The greater the stress due to handling, the less efficient the animals were. FCR increased with higher THI. It was concluded that changes in animal welfare caused by the rabbits’ reactivity to both climatic and individual factors affect animal productivit

Relationship between rectal temperature measured with a conventional thermometer and the temperature of several body regions measured by infrared thermography in fattening rabbits. Influence of different environmental factors

[EN] In clinical examination of rabbits, the temperature is usually recorded with a digital thermometer introduced rectally, an invasive procedure that could cause handling stress. The aim of this study was to assess body temperature using infrared thermography (IRT) in four areas of the rabbit’s anatomy: eye (ETT), outer ear (OETT), inner ear (IETT) and nose (NTT), and then validate it as an alternative measure to rectal temperature (RT) assessed with a conventional thermometer. Temperature samples were taken twice a week from 48 weaned rabbits of Spanish Common Rabbit breed during a 38-d fattening period. The factors considered were: doe from which the rabbits came (8 does), weeks of fattening period (4 to 5 wk), batch (3 periods of the year: April-May, June-July and January-February) and group size (cages with 1 to 7 rabbits). On average, the results were an RT of 38.48±0.02 °C; ETT of 37.31±0.05 °C; OETT of 29.09±0.26°C; IETT of 30.53±0.251 °C, and NTT of 33.29±0.11 °C (mean±se). Moderate, statistically significant positive correlations (P<0.001) were observed between RT and temperatures measured with infrared thermography (IETT, OETT, ETT and NTT), both in general (0.39 to 0.49) and intraclass (0.36 to 0.39), based on the batch, group size, week of fattening period and doe. The thermographic measurements which showed the highest correlation with RT were OETT and IETT. We also studied the effects that could influence the temperature variables evaluated by IRT and RT within each batch: for each week of the fattening period, for the group size and for the doe effect. We found significant differences (P<0.001) between weeks within the batch, with a tendency for the temperature of the rabbits to increase as the fattening period progressed. The doe effect (within the batch) did not show, on the whole, any statistically significant differences within batches. On the other hand, we did observe a trend towards higher temperatures as the group size increased. In conclusion, infrared thermography is an effective tool for body temperature assessment and correlates closely with RT, with IETT appearing as the best reference point for taking body temperature in fattening rabbits. Infrared thermography appeared as a suitable alternative to RT for body temperature assessment in rabbits, thus avoiding handling stress.Jaén-Téllez, JA.; Bartolomé, E.; Sánchez-Guerrero, MJ.; Valera, M.; González-Redondo, P. (2021). Relationship between rectal temperature measured with a conventional thermometer and the temperature of several body regions measured by infrared thermography in fattening rabbits. Influence of different environmental factors. World Rabbit Science. 29(4):263-273. https://doi.org/10.4995/wrs.2021.15556OJS263273294Ardiaca M., Brotóns N.J., Montesinos A. 2010. Aproximación a las urgencias y cuidados intensivos en conejos, psitácidas y reptiles. Clín. Vet. Peq. 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Hondarribia, Spain. 180-185.Hall L.W, Clarke K.W, Trim C.M. 2001. Veterinary anaesthesia. 10th Edition. W. B. Saunders, London, United Kingdom. https://doi.org/10.1016/B978-0-7020-2035-3.X5001-3Harris I. 1994. The laboratory rabbit. ANZCCART News, 7: 1-11.Jaén-Téllez J.A., Sánchez-Guerrero M.J., López-Campos J.I., Valera M., González-Redondo P. 2020. Acute stress assessment using infrared thermography in fattening rabbits reacting to handling under winter and summer conditions. Span. J. Agric. Res., 18, e0502, 13 pages. https://doi.org/10.5424/sjar/2020182-15706Kataoka N., Hioki H., Kaneko T., Nakamura K. 2014. Psychological stress activates a dorsomedial hypothalamusmedullary raphe circuit driving brown adipose tissue thermogenesis and hyperthermia. Cell. Metab. 20: 346-358. https://doi.org/10.1016/j.cmet.2014.05.018Knizková I., Kunc P., Gürdil G.A.K., Pinar Y., Selvi K.Ç. 2007. Applications of infrared thermography in animal production. J. 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Nonlinear modeling of trapping and thermal effects on GaAs and GaN MESFET/HEMT devices

A novel nonlinear model for MESFET/HEMT devices is presented. The model can be applied to low power (GaAs) and high power (GaN) devices with equal success. The model provides accurate simulation of the static (DC) and dynamic (Pulsed) I-V characteristics of the device over a wide bias and ambient temperature range (from -70ºC to +70ºC) without the need of an additional electro-thermal sub-circuit. This is an important issue in high power GaN HEMT devices where self-heating and current collapse due to traps is a more serious problem. The parameter extraction strategy of the new model is simple to implement. The robustness of the model when performing harmonic balance simulation makes it suitable for RF and microwave designers. Experimental results presented demonstrate the accuracy of the model when simulating both the small-signal and large-signal behavior of the device over a wide range of frequency, bias and ambient temperature operating points. The model described has been implemented in the Advanced Design System (ADS) simulator to validate the proposed approach without convergence problems.The authors would like to thank the Spanish Ministry of Science and Innovation (MICINN) by the financial support provided through projects CSD2008-00068, TEC2008-06684-C03-01 and TEC2011-29126-C03-01

Levantamiento Topográfico de calle "La Compostera" del Municipio de Ciudad Sandino, Departamento de Managua con una longitud 713 ml

En las obras de construcción civiles inicialmente se necesita una de sus ramas para los diversos estudios de ingeniería, siendo esta la Topografía ya que por medio de la aplicación de esta ciencia se obtiene una descripción detallada del terreno mediante el análisis planimétrico y altimétrico proporcionando la información para el diseño de la obra a construirse, y generando con esto proyecciones de rasante para una terraza estableciendo niveles deseados para dar inicio a la obra civil. Los levantamientos topográficos se realizan con el fin de determinar el conjunto de desigualdades que existen en la superficie que conforman el relieve, mostrando las dimensiones que el terreno presenta en la determinada área que se propone para el proyecto topográfico que se pretende realizar y su posición sobre la superficie de la tierra, de elementos naturales o instalaciones construidas por el hombre. En este tipo de levantamientos se toman los datos planimétricos y altimétricos para la representación gráfica y elaboración de mapas del área de estudi

Impedimetric Biosensor Based on a Hechtia argentea Lectin for the Detection of Salmonella spp.

A sensitive electrochemical detection method for Salmonella spp. was described, based on the use of Hechtia argentea lectin immobilised on a screen-printed gold electrode. The lectin was extracted from Hechtia argentea, a plant belonging to the Bromeliaceae family. The lectin with molecular weight near 27.4 kDa showed selectivity towards D-mannose, contained on the lipopolysaccharide cell wall of Salmonella spp. Carbohydrate selectivity of the lectin was measured as a change in impedance with respect to concentration. The binding of the bacteria to the biosensor surface increased impedance with increasing concentrations of Salmonella spp., achieving a linear range of detection of 15–2.57 × 107 CFU mL−1, with a limit of detection of 5 CFU mL−1. Increases in impedance were measured using electrochemical impedance spectroscopy and analysed using Nyquist plots. The biosensor was applied in analysis of hen egg samples, and the results were consistent with those obtained using the official analysis methodologyS

ANÁLISIS TÉRMICO DE LOS SUBSISTEMAS ELECTRÓNICOS EN UN RECINTO DE CANSAT (THERMAL ANALYSIS OF ELECTRONIC SUBSYSTEMS IN A CANSAT ENCLOSURE)

ResumenSe presenta la medición de temperatura de cinco regiones térmicas que influyen en la operación de los componentes electrónicos del picosatélite tipo lata (CanSat). En el análisis térmico de los subsistemas electrónicos se consideran los valores que reflejan las hojas técnicas de la resistencia térmica unión-encapsulado tanto de la computadora de abordo, como del sistema de adquisición de datos y el subsistema de comunicaciones, así como la temperatura del recinto y la temperatura externa al CanSat. Con la distribución física de los subsistemas, se logró mantener un equilibrio térmico confortable observando que en las lecturas no se rebasaron los márgenes de seguridad de los componentes electrónicos, por lo que ningún subsistema alcanzó esfuerzos térmicos, lo que permite prolongar su vida útil. Los resultados muestran que la fuente de calor, de los tres subsistemas genera aproximadamente 200 mW de calor. Las lecturas de prueba se levantaron en la Laguna Salada, que es una de las zonas más calurosas del país, en este lugar frecuentemente se alcanzan los 50 oC en verano y en invierno rara vez llega a 0 oC. El área de del recinto fue de 282.74 cm2, y la resistencia de radiación de la superficie de la lata se estimó en 100 mW / 282.74 cm2 = 0.3638 mW/cm2. Los componentes electrónicos funcionaron dentro de la región segura de las temperaturas y no sobrepasaron el límite de los 115 ºC.Palabras Claves: Región térmica, Resistencia térmica, Temperatura de unión. AbstractThe measurement of the temperature of five thermal regions that influence the operation of the electronic components of the can-type picosatellite (CanSat) is presented. In the thermal analysis of the electronic sub-systems the values that the technical sheets of the union-encapsulated mechanical resistance of the onboard computer, as well as the data acquisition system and the communication subsystem, as well as the temperature of the enclosure and the external temperature to CanSat. With the physical distribution of the subsystems, it was possible to maintain a comfortable thermal equilibrium, it was observed that the readings were not exceeded the safety margins of the electronic components, which allows their useful life to be extended. The results show that the heat source, of the three subsystems, generated 200 mW of heat. The test readings were raised in the Laguna Salada, which is one of the warmest areas of the country, in this place frequently reach 50 oC in summer and in winter rarely reaches 0 oC. The area of the enclosure was 282.74 cm2, and the radiation resistance of the can surface was estimated at 100 mW / 282.74 cm2 = 0.3638 mW / cm2. The electronic components operated within the safe region of the temperatures and did not exceed the limit of 115 oC.Keywords: Junction temperature, thermal region, thermal resistance

Improving project management competencies of engineering students in the new ehea

The introduction of the new European Higher Education Area (EHEA) requires lecturers change or adapt their subject teaching plans and they have to apply a competency-based approach in different engineering degrees (industrial, computing, agriculture, forestry and mining). Because of this situation, several professors from the Universities of Huelva and Pablo Olavide of Seville, are conducting a set of innovative teaching experiences, aimed to find the most effective way to help students develop many of the project management skills, described in the IPMA ICB 3.0 international standard. In this communication, the fundamentals of these experiences, the main findings and conclusions are shown. It can be interesting to the lecturers and trainers who want to improve their teaching in project management. La implantación del nuevo espacio europeo de educación superior (EEES) obliga a que los profesores tengan que cambiar o adaptar los planes docentes de sus asignaturas y a adoptar un enfoque basado en competencias en las distintas titulaciones de ingeniería (industrial, informática, agrícola, forestal y minas). Ante esta situación varios profesores de las Universidades de Huelva y Pablo Olavide de Sevilla, estamos realizando una serie de experiencias de innovación docente, destinadas a encontrar la forma más eficaz de lograr que nuestros alumnos desarrollen bastantes de las competencias de dirección de proyectos descritas en el estándar internacional IPMA ICB 3.0. En esta comunicación se describen los fundamentos de dichas experiencias, se discuten sus resultados y se extraen conclusiones que pueden resultar de interés para cualquier profesor que quiera mejorar su docencia en dirección de proyectos