An Analysis of Global Research Trends on Greenhouse Technology: Towards a Sustainable Agriculture

Greenhouse farming is an agricultural management system that has demonstrated its efficiency in intensifying food production. These systems constitute a feasible alternative for ensuring food supply, which is one of the greatest challenges faced by humankind in the twenty-first century. Technology has been able to meet the challenges related to greenhouse farming in both contributing to overcoming its limitations, correcting adverse impacts and ensuring system sustainability. The objective of this article is to analyse the global research trends in greenhouse technology over the last two decades, in order to identify the main driving agents, the most outstanding research lines and possible gaps in the literature. Different methodologies have been used for the analysis; both quantitative and qualitative. The principal results show that there are different relevant lines of research related to different aspects of greenhouse farming: the use of water for irrigation, the design of the optimum structure of the greenhouse, conserving the soil in the best growing conditions, energy consumption of the system as a whole, climate control within the facility and pest control. The research is characterized by the being composed largely of ad hoc studies, which hinders the international collaboration between researchers and institutions. The research approach has shifted from being focused on increasing production and cost savings to aspects related to resource conservation and sustainability

Perceptions and Acceptance of Desalinated Seawater for Irrigation: A Case Study in the Níjar District (Southeast Spain)

In the context of increasing demand for irrigation water—but, at the same time, with the constraints in the supply from traditional resources—desalinated seawater has been recognized as one of the alternative sources of water to increase the supply for agricultural irrigation. However, its use among farmers has not yet started to expand. Policy makers need to understand what is causing the low acceptance levels of farmers, and how their attitudes could be improved. This is the first study that has conducted an analysis of farmers’ perceptions and acceptance of the use of desalinated seawater for irrigation. The study is based on collected data from a survey completed by farmers in southeastern Spain who do not use desalinated seawater. The main results indicate that desalinated seawater as a water supply source has the lowest acceptance level for farmers. Barriers for its use are price, the need for additional fertilization, and the perception that it would negatively affect the yield and crop quality. The farmers’ general level of knowledge about the impact of using desalinated seawater in agriculture is extremely low. Furthermore, farmers consider it a priority that their startup investment should be subsidized and that water prices should be reduced. Based on the study findings, this paper makes recommendations for the decision-making process in order to improve farmers’ acceptance levels

Modeling Confined Cell Migration Mediated by Cytoskeleton Dynamics

Cell migration is an important biological process that has generated increasing interest during the last several years. This process is based on three phases: protrusion at the front end of the cell, de-adhesion at the rear end and contraction of the cell body, all of them coordinated due to the polymerization/depolymerization of certain cytoskeletal proteins. The aim of this work is to present a mathematical model to simulate the actin polymerization/depolymerization process that regulates the final outcome of cell migration process, considering all the above phases, in a particular case: when the cell is confined in a microfluidic channel. Under these specific conditions, cell migration can be approximated by using one-dimensional simulations. We will propose a system of reaction-diffusion equations to simulate the behavior of the cytoskeletal proteins responsible for protrusion and contraction in the cell, coupled with the mechanical response of the cell, computing its deformations and stresses. Furthermore, a numerical procedure is presented in order to simulate the whole process in a moving and deformable domain corresponding to the cell body

Residual-based stabilization of the finite element approximation to the acoustic perturbation equations for low Mach number aeroacoustics

This is the peer reviewed version of the following article: [Guasch, O., Sánchez-Martín, P., Pont, A., Baiges, J., and Codina, R. (2016) Residual-based stabilization of the finite element approximation to the acoustic perturbation equations for low Mach number aeroacoustics. Int. J. Numer. Meth. Fluids, 82: 839–857. doi: 10.1002/fld.4243], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/fld.4243/abstract. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The acoustic perturbation equations (APE) are suitable to predict aerodynamic noise in the presence of a non-uniform mean flow. As for any hybrid computational aeroacoustics approach, a first computational fluid dynamics simulation is carried out from which the mean flow characteristics and acoustic sources are obtained. In a second step, the APE are solved to get the acoustic pressure and particle velocity fields. However, resorting to the finite element method (FEM) for that purpose is not straightforward. Whereas mixed finite elements satisfying an appropriate inf–sup compatibility condition can be built in the case of no mean flow, that is, for the standard wave equation in mixed form, these are difficult to implement and their good performance is yet to be checked for more complex wave operators. As a consequence, strong simplifying assumptions are usually considered when solving the APE with FEM. It is possible to avoid them by resorting to stabilized formulations. In this work, a residual-based stabilized FEM is presented for the APE at low Mach numbers, which allows one to deal with the APE convective and reaction terms in its full extent. The key of the approach resides in the design of the matrix of stabilization parameters. The performance of the formulation and the contributions of the different terms in the equations are tested for an acoustic pulse propagating in sheared-solenoidal mean flow, and for the aeolian tone generated by flow past a two-dimensional cylinder.Peer ReviewedPostprint (author's final draft

Rainwater Harvesting for Agricultural Irrigation: An Analysis of Global Research

Within a context of scarce water resources for agriculture, rainwater harvesting constitutes a promising alternative that has been studied by different disciplines in recent years. This article analyses the dynamics of global research on rainwater harvesting for agricultural irrigation over the last two decades. To do this, qualitative systematic analysis and quantitative bibliometric analysis have been carried out. The results reveal that this line of research is becoming increasingly important within research on irrigation. Environmental sciences and agricultural and biological sciences are the most relevant subject areas. Agricultural Water Management, Physics and Chemistry of the Earth, and Irrigation and Drainage are the journals that have published the most articles on the subject. India, China, the United States (USA), South Africa, and the Netherlands are the countries that lead this line of research. Although significant progress has been made in this subject area, it is necessary to increase the number of studies on the capacity of rainwater harvesting systems to cover irrigation needs in different farming contexts, the factors that determine their adoption by farmers, the economic and financial feasibility of their implementation, and their contribution to mitigating global climate change

Economic cycles and environmental crisis in arid southeastern Spain. A historical perspective

The arid southeast region has been one of the areas with the oldest settlement in the Iberian Peninsula. Despite limitations imposed by lack of water and low soil fertility, a great number of dwellers have settled in this land for three thousand years thanks to its easy access to the commercial paths of the Mediter- ranean. The area is currently under great territorial and socioeconomic transformation activated by intensive agriculture through greenhouses and irrigation. The history of this territory offers a series of successful and downward cycles determined, from an ecological and economic point of view, by its integration in different stages of the globalization process. Most recently, in the 19th century an intensive deforestation process took place caused by the mining and iron industry. The deep economic and social crisis which followed the declining of this development model brought also about an ecological crisis. In the second half of the 20th century, negative environmental effects have continued and extended to the next generations with problems such as territorial saturation and aquifer depletion that characterize the new intensive agriculture under plastic. The current debate about the sustainability of this developmental model in such vulnerable environment can take advantage of some ecological lessons from the past

El mármol de Macael. Evolución de los medios de transporte

Aunque los productos de cantera tienden a emplearse cerca del lugar de extracción, en ocasiones, por su calidad, esta norma se rompe. Es el caso de muchas rocas ornamentales y, en particular, del mármol de Macael, demandado desde hace siglos para embellecer abundantes y significativas edificaciones. Los medios para el transporte el mármol han ido evolucionando con el tiempo. Hasta finales del XIX los carros de bueyes se empleaban tanto para llevar el producto desde las canteras a los talleres de corte, como para su traslado hasta el destino final o hasta la costa para embarcarlo. A partir de 1894 el ferrocarril comenzó a adquirir protagonismo para sacar el mármol de la comarca, y desde 1950 los camiones fueron sustituyendo a los carros para llevar el producto bruto hasta las fábricas de elaboración. Desde entonces el transporte por carretera fue ganando terreno en detrimento del ferrocarril, sustitución que fue definitiva en 1984 con el cierre de la línea férrea Guadix-Almendricos. Actualmente, el transporte por carretera es el medio habitual para llevar el producto a los destinos finales nacionales y europeos, y para su traslado a los puertos en los que se embarca hacia otros destinos exteriores. Quarry material is normally used near its extraction place. However, we often find that it is not the case, especially with decorative rocks. This happens to the marble from Macael (Almería, Southern Spain), which has had for centuries a great demand to beatify many significant buildings. The means of marble transport have evolved over the time. Till the end of the 19th Century, ox carts were used to carry the quarry material from the explotations to the cutting establishments, as well as to transport the processed products to its final destination or to the coast fot its shipping. From 1894 on, the train became an important means of transport to take the marble out of the region and since 1950 lorries have replaced the carts to take the quarry to the processing firms. Since then the road transport has become more important than the train. It was finally completedly replaced in 1984, when the train line Guadix-Almendricos was closed. Nowadays, road transport is the most common means of transport to take the product to its final destination in Spain and Europe, or to the ports where it will be shipped

Retos en el diseño de un generador caótico en tecnología CMOS submicrónica

En este artículo se exponen los retos para llevar a cabo el diseño de un generador caótico, basado en el circuito de Chua, en tecnología CMOS submicrónica. El diseño analógico del generador caótico se complementa con un control digital, que proporciona programabilidad para definir distintos estados (claves) que aumenten la seguridad del cifrado. Además, se analizan distintas variables (temperatura, mismatching...) que pueden afectar a la sincronización de dos sistemas idealmente idénticos, impidiendo el descifrado de la información transmitida.Los autores agradecen la ayuda concedida por el Centro Universitario de la Defensa (2013-12) para iniciar esta línea de investigación, así como la colaboración del Grupo de Diseño Electrónico mediante el proyecto del Plan Nacional de I+D+i TEC2011-23211

Territory, Cluster and Competitiveness of the Intensive Horticulture in Almería (Spain)

Almería is Spain’s leading area for the production and exportation of vegetables. In this province we can find the largest area of greenhouses in the world, around which a major agroindustrial cluster has arisen. The present study follows a holistic approach to analyse its development and the modification of its sources of advantage. For this purpose, Porter’s theoretical and analytical framework is considered. The particular natural resources of the territory were fundamental in the growth of this sector in the 1970’s, allowing it to achieve absolute comparative advantages. Nowadays, the agroindustrial cluster that has built up around the greenhouse industry has enhanced the competitiveness of the sector by generating systemic and dynamic competitive advantages

Local development policy in the Marble Area in Almería

En Almería se encuentra ubicada la principal zona marmórea de España tanto por sus reservas como por su calidad. En torno a la producción, elaboración y comercialización de este producto se ha generado un importante sistema productivo local. En este artículo se analizan los planes de desarrollo local implantados en la Comarca desde mediados de la década de los ochenta del pasado siglo, y se muestran las repercusiones que han tenido en la mejora de la productividad y de la competitividad del sector en los ámbitos de la extracción, la transformación, la comercialización y la tecnología.The main marble area in Spain, regarding its reserves and quality, is located in Almería. Around the production, elaboration and trading of this produce, a relevant local production system has arisen. This paper analyzes the local development plans implemented in the region since mid 80’s. It also shows the impacts on a higher productivity and sector competitiveness in the extraction, transformation, trading and technical fields