Recolección en olivar

España es el primer productor mundial de aceite de oliva. En este artículo se describen los equipos para la recogida de la aceituna

Eterificació de l’alcohol furfurílic a levulinat de butil utilitzant resines d’intercanvi iònic

Treballs Finals de Grau d'Enginyeria Química, Facultat de Química, Universitat de Barcelona, Curs: 2015-2016, Tutor: Roger Bringué TomàsThe objective of this research is the study of the synthesis reaction of butyl levulinate (BL) from furfuryl alcohol (FA) and 1-butanol (BUT) by using commercial ion-exchange resins as catalysts. There’s two stages in the reaction: a conversion of FA to 2-(butoxymethyl)furan (Bmf) and the production of BL from the intermediate mentioned. The main drawback of this reaction is the polymerization of FA, producing some insoluble substances as oligomeric products, for example, 5-5-dibutoxy-2-pentanone (DBPent), resulting in a drop of selectivity. During the last years, the production of BL is being investigated, since interest in the use of lignocellulosic biomass for the production of chemicals, fuel or energy increases at the same time that global awareness do about fuels resource depletion and the environmental impact causes to carry out some industrial processes. So the search for an effective and economical process for obtaining this product without bringing about severe changes in the environment is imperative. The project will work at a temperature of 100°C using different types of ion-exchange resins (macroreticulars and gel-type resins) to carry out a comparison of the selectivity, conversion and yield obtained with the use of each of them and give possible explanations of observed facts through their individual characteristics (degree of crosslinking, acid capacity and DVB percentage). To see the reaction rates varying the catalysts, representations of the evolution of Bmf and BL moles produced will be realized. The effect of the temperature in the reaction is studied too, carrying out the reaction at temperatures among 80 ºC and 110 ºC. Finally, two different initial molar ratio are used to see the effect of this parameter along the reaction course

Inspección de frutas y hortalizas mediante videocámara, estado actual de la técnica (II)

En los últimos años hemos asistido a cambios notables en el ámbito de la inspección automatizada de frutas y hortalizas. En este artículo repasamos algunos conceptos y avances en relación con la clasificación de productos hortofrutícolas mediante videocámara. Hace una década la detección de defectos externos no estaba conseguida, mientras que sí lo estaba la clasificación por tamaño y color. Actualmente podemos decir que la clasificación en base a defectos externos funciona bien: los equipos comerciales son capaces de detectar dichos defectos, separando los frutos de la máxima calidad comercial de aquellos de calidad inferior. El problema tradicional de la confusión del cáliz o el pedúnculo del fruto con un defecto se puede considerar superado. Sin embargo, la mayoría de los equipos actualmente instalados en las centrales hortofrutícolas no son capaces de discernir el tipo de defecto. Conseguir esto sería interesante, ya que permitiría conocer qué defectos son los más frecuentes, y se podría actuar de cara a la campaña siguiente en relación con el manejo del cultivo o del producto en postcosecha. Recientemente se han desarrollado sistemas de clasificación mediante videocámara capaces de discernir el tipo de defecto y de identificar podredumbre

Medición en campo de la potencia máxima entregada por paneles fotovoltaicos bajo condiciones estándar de medida

El uso de la electricidad en el medio rural necesita de fuentes de energía autónomas. Una de las opciones que sigue ganando fuerza debido a la bajada de precios es la generación de electricidad mediante paneles solares fotovoltaicos. Los paneles fotovoltaicos tienen garantías que oscilan entre los 20 y 25 años sobre la potencia máxima entregada. Medir dicha potencia necesita de unas condiciones que habitualmente no se dan y de equipos de medida normalmente muy caros. Este trabajo presenta un equipo de medida basado en PC para paneles fotovoltaicos. Asimismo discute sobre la metodología a utilizar en campo para obtener de la forma más precisa posible, medidas de la potencia entregada por un panel fotovoltaico en condiciones estándar de medida. Se considera de gran interés disponer de un mecanismo con la suficiente precisión para determinar si la bajada de potencia de un módulo está dentro de las condiciones de garantía

Success possibilities of grid parity in particular cases in the new spanish regulatory framework

During the last 10 years the Spanish photovoltaic market has experienced one of the most important increases worldwide. The continuous raise on the price of the electricity in Spain, as in other European countries, USA and Japan, as well as the decrease of the cost of solar photovoltaic systems along this decade is opening a new way to reach grid parity point in some particular scenarios. A new Spanish legislation is being performed toward selfconsumption, and it is in this new context where the grid parity in a wide sense could be achieved. This work will study different cases in Spain, in order to determine whether grid parity would be possible along 2012. Keywords: grid parity, self-consumption, photovoltaic, net-meterin

Economic feasibility analysis of choices for not connected clients: photovoltaic off-grid systems, compared to grid based system

Off-grid photovoltaic systems are less constrained by national regulations than their grid-connected counterparts. Off-grid systems do not depend on feed-in tariff and the analysis of their cost-efficiency is more stable along time. This work calculates the economic parameters for two different technologies of photovoltaic systems and compares the levelized cost of electricity (LCOE), with the price of the electricity, including the cost for the connection of the system related to the distance to the grid. The results show that the sustained decline in photovoltaic module¿s price contributes to subsequent decline in LCOE, whereas the increase in the price of grid electricity and materials related to the connection makes off-grid systems more cost-effective for remote areas. Finally, to determine if the photovoltaic system could be an economic alternative for investments in remote regions, a comparison between the cost of grid extension and the LCOE of a high capacity photovoltaic system was undertaken

Analysis of air mass dependence of three photovoltaic arrays

The solar spectrum, which is also could be described by air mass factor, has a significant relationship with the performance of photovoltaic modules. The air mass dependence has been investigated by a theoretical method as well as an actual case of three different photovoltaic arrays: polycrystalline silicon, amorphous silicon and cadmium telluride, at the EUIT Agrícola-UPM (Madrid, Spain, 40.4426oN, 3.7295oW). The calculating results show that: AM dependence of poly-Si array is positive because an elevating AM-value indicates a red shift and poly-Si module is more red sensitive; On the contrary, as a-Si module and CdTe module are more blue sensitive, their AM dependences are negative. Furthermore, the outdoor AM dependences of three arrays are corresponding to the calculating results although the thermal annealing effect could be superimposed on spectral effect in the case of a-Si. Keywords: PV system, spectral response, polycrystalline silicon, a-Si, CdT

Student Reciprocal Peer Teaching as a Method for Active Learning: An Experience in an Electrotechnical Laboratory

Active learning is one of the most efficient mechanisms for learning, according to the psychology of learning. When students act as teachers for other students, the communication is more fluent and knowledge is transferred easier than in a traditional classroom. This teaching method is referred to in the literature as reciprocal peer teaching. In this study, the method is applied to laboratory sessions of a higher education institution course, and the students who act as teachers are referred to as ‘‘laboratory monitors.’’ A particular way to select the monitors and its impact in the final marks is proposed. A total of 181 students participated in the experiment, experiences with laboratory monitors are discussed, and methods for motivating and training laboratory monitors and regular students are proposed. The types of laboratory sessions that can be led by classmates are discussed. This work is related to the changes in teaching methods in the Spanish higher education system, prompted by the Bologna Process for the construction of the European Higher Education Are

Tipificación y evaluación de la sensibilidad antimicrobiana de cepas de campylobacter jejuni y campylobacter coli aisladas de pollos parrilleros del Bajo Chaco – Paraguay.

El objetivo general del estudio fue Tipificar Campylobacter jejuni, Campylobacter coli y evaluar la sensibilidad de cepas aisladas de pollos parrilleros del Bajo Chaco – Paraguay.CONACYT - Consejo Nacional de Ciencias y TecnologíaPROCIENCI

Tecnología de Visión Artificial 3D

La visión artificial es una herramienta potente para la inspección externa de productos alimentarios. Actualmente es rara la industria alimentaria que no emplea tecnología para el control de calidad de la producción. La mayoría de los sistemas de visión instalados actualmente son 2D, es decir, analizan imágenes planas tomadas "a vista de pájaro": estas imágenes permiten evaluar las características de tamaño, forma y color de los productos. Pero cada vez hay más aplicaciones en las que además de las características anteriores conviene disponer de un modelo 3D del objeto inspeccionado, lo cual se consigue con equipos de visión artificial 3D