Refrigeration Capacity and Effect of Ageing on the Operation of Cellulose Evaporative Cooling Pads, by Wind Tunnel Analysis

This study investigates the temperature reduction capacity and water consumption of a fan-pad system installed in a greenhouse located in the coastal regions of Almería. The suitability of this system for coastal zones with high environmental humidity during the summer is analyzed. Historical temperature and relative humidity series are studied, obtaining the thermal difference and maximum, medium, and minimum monthly water consumption of the pads based on the operation data of the pads. Despite the high relative humidity of the air in the hottest hours of the day, a decrease of 5.92 ºC in the mean temperature and a water consumption of 13.55 l/h per square meter of an evaporative cooling pad are obtained in the month of August. Additionally, the operation of a cellulose evaporative cooling pad installed for 3 years in a greenhouse is analyzed in a wind tunnel and compared with that of a new pad of the same model. Over time and with low maintenance, the porosity of the pad decreases due to salt incrustation. The salt incrustation makes airflow more difficult in the pad, increasing the pressure drop by 170.04%; however, the air saturation efficiency of the pad increases by 6.6% due to the greater contact time between the air and the waterMinisterio de Economía y Competitividad de España AGL2015-68050-RUnión Europea (FEDER) AGL2015-68050-

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Assessment of the cooling potential of an indoor living wall using different substrates in a warm climate

The use of vertical greenery systems in buildings is becoming very popular as they provide several benefits. In this work, the influence of an indoor living wall on the temperature and humidity in a hall inside the School of Agricultural Engineering (University of Seville) was studied. Four different substrates, Geotextile, Epiweb, Xaxim and coconut fibre, were used to grow the plants in order to assess their performance. Several parameters such as temperature, humidity, plant growth or water consumption were monitored and analyzed during a 4-month period. The cooling effect of the living wall was proven, with an average reduction of 4°C over the room temperature though maximum decrements of 6°C have been observed in warmer conditions. Higher air humidity levels were experienced near the living wall, increasing the overall humidity in the room. All the substrates tested were suitable for plant growing and their behaviour was similar. Geotextile showed the best cooling capacity but higher water consumption, coconut fibre presented degradation problems and Epiweb performance was the poorest. Therefore, these systems have been proven to be very useful and interesting for warm indoor environments due to the cooling effect observed in addition to their bio-filtration capacity and the aesthetic component

Energy Efficiency in Greenhouse Evaporative Cooling Techniques: Cooling Boxes versus Cellulose Pads

Evaporative cooling systems using a combination of evaporative pads and extractor fans require greenhouses to be hermetic. The greatest concentration of greenhouses in the world is located in southeast Spain, but these tend not to be hermetic structures and consequently can only rely on fogging systems as evaporative cooling techniques. Evaporative cooling boxes provide an alternative to such systems. Using a low-speed wind tunnel, the present work has compared the performance of this system with four pads of differing geometry and thickness manufactured by two different companies. The results obtained show that the plastic packing in the cooling unit produces a pressure drop of 11.05 Pa at 2 m·s−1, which is between 51.27% and 94.87% lower than that produced by the cellulose pads. This pressure drop was not influenced by increases in the water flow. The evaporative cooling boxes presented greater saturation efficiency at the same flow, namely 82.63%, as opposed to an average figure of 65% for the cellulose pads; and also had a lower specific consumption of water, at around 3.05 L·h−1·m−2·°C−1. Consequently, we conclude that evaporative cooling boxes are a good option for cooling non-hermetic greenhouses such as those most frequently used in the Mediterranean basin

Evaluación y revisión de las proporciones recomendadas para mezclas de concreto en obras menores utilizando dos fuentes de agregados nacionales.

Proyecto de Graduación (Licenciatura en Ingeniería en Construcción). Instituto Tecnológico de Costa Rica. Escuela de Ingeniería en Construcción, 2002.Se presentan los resultados de la evaluación y revisión de las proporciones recomendadas para mezclas de concreto en obras menores, utilizando agregados procedentes de dos fuentes, una en Guápiles y otra en Heredia y a la vez recomendar la más viable para realizar un proyecto en Heredia. Dicho análisis consideró el diseño de mezclas de concreto con los agregados de cada fuente a partir del proporcionamiento por tablas en su condición original, granulometría corregida y según la norma ACI 211. Se consideraron dos resistencias a compresión del concreto, comúnmente usadas en obras menores: 175 y 210 kg/cm2. Para lo anterior fue necesario aplicar la norma 10854-MEIC y considerar las principales propiedades y condiciones. Así mismo se hace una referencia mediante entrevistas a diferentes empresas relacionadas con el proceso, comercio y venta de materiales. Los resultados obtenidos muestran un cumplimiento parcial del objetivo. Los diseños cumplen satisfactoriamente para la fuente de Guápiles, pero son deficientes en el caso de la fuente de Heredia. Se logran establecer alcances y limitaciones para cada método de diseño, así como la importancia e influencia de los agregados en la resistencia final del concreto. Se determina también que a nivel comercial existe un desconocimiento e incumplimiento general en cuanto a la normativa vigente, tanto de los productores y proveedores como del consumidor, a excepción de unas pocas empresas importantes del ramo

Restoration of the Palacio de Mayoralgo in Cáceres (Spain).

[Abstract] The Palace Mayoralgo (13th/16th century), in St. Maria Square in the Old City of Cáceres was acquired it in 1999 to be the headquarters of the Presidency of the Caja de Extremadura. It had been empty and unused for many years, and it was also severely damaged since it was hit by bombs during the Spanish Civil War in 1937. Different well known experts, in a multidisciplinary work, have participated both in the writing of the project to optimize architectural and constructive solutions. The development of the project and the works began in from August 2000 and finished in August 2004. The finding of the Roman archaeological remains at the beginning of the works forced some adjustments in the initial design in order to preserve and protect them. The project and the work carried out have meant, on one hand, a considerable preservation work that increases the value of the Architectural Heritage

Estudio analítico de un modelo predador-presa con efecto Allee

El efecto Allee se introduce en modelos de competencia intraespecífica y dos especies en competencia. Se utiliza análisis de plano de fase y simulación para investigar la dinámica de estos modelos. Combinando modelación simple y simulación, se demuestra que el efecto Allee por sí solo podría llevar sistemas de dos especies en competencia a estados estables alternativos. En tales sistemas, si la competencia interespecífica es intensa, las dos especies podrían extinguirse aunque su densidad de población sea alta

Chaotic image encryption using hopfield and hindmarsh–rose neurons implemented on FPGA

Chaotic systems implemented by artificial neural networks are good candidates for data encryption. In this manner, this paper introduces the cryptographic application of the Hopfield and the Hindmarsh–Rose neurons. The contribution is focused on finding suitable coefficient values of the neurons to generate robust random binary sequences that can be used in image encryption. This task is performed by evaluating the bifurcation diagrams from which one chooses appropriate coefficient values of the mathematical models that produce high positive Lyapunov exponent and Kaplan–Yorke dimension values, which are computed using TISEAN. The randomness of both the Hopfield and the Hindmarsh–Rose neurons is evaluated from chaotic time series data by performing National Institute of Standard and Technology (NIST) tests. The implementation of both neurons is done using field-programmable gate arrays whose architectures are used to develop an encryption system for RGB images. The success of the encryption system is confirmed by performing correlation, histogram, variance, entropy, and Number of Pixel Change Rate (NPCR) tests