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Cartagena, Spain
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Zueco J.,UPCT | Ahmed S.,Fluid Dynamics Research | Lopez-Gonzalez L.M.,University of La Rioja
International Journal of Heat and Mass Transfer | Year: 2017

In this paper we present the numerical solution of the problem 2-D unsteady free convective heat and mass transfer flow over a moving semi-infinite vertical porous plate with thermal diffusion in presence of magnetic field, dissipative heat and Soret effects taking into account the induced magnetic field. The steady-state numerical solutions for the velocity field, induced magnetic field, temperature distribution and concentration distribution are obtained by the explicit finite difference method and the network simulation method. The obtained results have been shown graphically. The obtained numerical results were compared with other author data to demonstrate the efficiency of the method used, moreover all the cases the convergence is always quickly reached. An increase in Soret or Eckert number is found to strongly enhance the fluid velocity and temperature values, and this effect is reversed for the induced magnetic field. It is found that the flow velocity decreases with the increase in Hartmann and magnetic Prandtl number, and an opposite behaviour is observed for the fluid temperature. Applications of the study arise in the thermal plasma reactor modelling, the electromagnetic induction, MHD transport phenomena in chromatographic systems, and the magnetic field control of materials processing. The results show that both methods provide excellent approximations to the solution of this nonlinear system with high accuracy. © 2017 Elsevier Ltd


Manteca I.A.,Geologica y Cartografica | Estrella T.R.,Geologica y Cartografica | Alhama F.,UPCT
Water Resources Management | Year: 2012

The Agua Amarga coastal aquifer, located in the southeast of Spain (Alicante province) has suffered a significant decrease in its piezometric levels due to its use to supply water to Alicante I and II desalination plants. In order to recover its natural levels and to preserve the salt marsh of ecological interest linked to the aquifer, whose origin is related to ancient saltworks, a pilot scheme based on depositing seawater over the salt marsh surface has been carried out from December 2009 to July 2010. As a result, piezometric levels have increased by around 2 and 3 m below the salt marsh and a general decrease in groundwater salinity of between 15 and 100 g/l has been measured. A flow-transport numerical model with SEAWAT is used to assess and evaluate the seawater depositing programme. © 2012 Springer Science+Business Media B.V.


Gallego-Elvira B.,French National Institute for Agricultural Research | Martinez-Alvarez V.,UPCT | Pittaway P.,NCEA | Brink G.,NCEA | Martin-Gorriz B.,UPCT
Water Resources Management | Year: 2013

Monolayer products can potentially provide a cost effective solution for reducing evaporative loss from water storages. Commercial adoption has been low, due to the extreme variability of product performance. In this study, the efficiency of three monolayer compounds (stearyl alcohol, ethylene glycol monooctadecyl ether and the commercial product WaterSavr) in reducing evaporation were tested at three controlled wind speeds inside a glasshouse in class-A evaporation pans. Water levels and micrometeorological conditions were monitored to document the impact of prevailing atmospheric conditions on monolayer performance. The evaporation reduction ranged from 13 to 71 % depending on the product and micrometeorological conditions. The ethylene glycol monooctadecyl ether was most effective reducing evaporation across all wind speeds. Atmospheric conditions markedly affected monolayer products' performance. All monolayers were most effective when the wind was sufficient to drive evaporative loss but lacked the force to disrupt the condensed monolayer (1. 5 m s-1). Continuous wind of 3 m s-1 disrupted the condensed monolayer and substantially decreased the product performance. Without wind, the resistance to evaporation induced by monolayers had little additional effect. When atmospheric evaporation demand was very low, the evaporation suppression efficiency was minimized. High temperatures and high incoming radiation negatively affected the persistence of the condensed monolayer and decreased product performance. These results highlight the importance of analysing micrometeorological conditions when assessing product performance. © 2013 Springer Science+Business Media Dordrecht.


Agua Amarga coastal aquifer in southern Spain has been the subject of chemical and physical measurements since May 2008 in order to monitor the potential effects of water withdrawal for the Alicante desalination plants on the salt marsh linked to the aquifer. Electrical conductivity contour maps and depth profiles, piezometric-head contour maps, hydrochemical analyses, isotopic characterizations and temperature depth profiles show not only the saltwater intrusion caused by water abstraction, but also the presence of a pronounced convective density-driven flow below the salt marsh; this flow was a consequence of saltwork activity in the early 1900s which generated saline groundwater contamination. The influence of a seawater recharge programme, carried out over the salt marsh in 2009-2010, on the diminishing groundwater salinity and the recovery of groundwater levels is also studied. Based on collected field data, the project provides a deeper understanding of how these successive anthropogenic interventions have modified flow and mixing processes in Agua Amarga aquifer. © 2012 Springer-Verlag.


Guerrero-Gonzalez A.,Technical University of Cartagena | Garcia-Cordova F.,Technical University of Cartagena | Ruz-Vila F.A.,UPCT
International Review of Electrical Engineering | Year: 2010

In this paper, an autonomous vehicle capable of operating during large periods of time for observation and monitoring is proposed. The vehicle integrates photovoltaic panels and a methanol fuel cell, together with a neurobiological inspired control architecture for intelligent navigation. In this work, the autonomy of the vehicle is evaluated in several scenarios, when the vehicle is moving in mission and when the vehicle is not moving. The energetical management module generates recharge missions with a variable priority level depending on the batteries level to the mission planner. The biologically inspired neural network architecture proposed for nonholonomic mobile robots makes the integration of a kinematic adaptive neuro-controller for trajectory tracking and an obstacle avoidance adaptive neuro- controller possible. © 2010 Praise Worthy Prize S.r.l. - All rights reserved.


Martinez-Frutos J.,Technical University of Cartagena | Kessler M.,UPCT | Periago F.,UPCT
ESAIM - Control, Optimisation and Calculus of Variations | Year: 2015

We consider a shape optimization problem for an elliptic partial differential equation with uncertainty in its input data. The design variable enters the lower-order term of the state equation and is modeled through the characteristic function of a measurable subset of the spatial domain. As usual, a measure constraint is imposed on the design variable. In order to compute a robust optimal shape, the objective function involves a weighted sum of both the mean and the variance of the compliance. Since the optimization problem is not convex, a full relaxation of it is first obtained. The relaxed problem is then solved numerically by using a gradient-based optimization algorithm. To this end, the adjoint method is used to compute the continuous gradient of the cost function. Since the variance enters the cost function, the underlying adjoint equation is non-local in the probabilistic space. Both the direct and adjoint equations are solved numerically by using a sparse grid stochastic collocation method. Three numerical experiments in 2D illustrate the theoretical results and show the computational issues which arise when uncertainty is quantified through random fields. © EDP Sciences, SMAI, 2015.


Conesa M.R.,Technical University of Cartagena | Garcia-Salinas M.D.,Technical University of Cartagena | de la Rosa J.M.,Technical University of Cartagena | Fernandez-Trujillo J.P.,UPCT | And 2 more authors.
Scientia Horticulturae | Year: 2014

The quality traits of fruit harvested from 'Fortune' mandarin trees (Citrus clementina Hort. Ex. Tanaka×C. reticulata Blanco) subjected to different irrigation strategies was studied at harvest, during cold storage (33 d at 5°C), and after an additional shelf-life period of 5 d at 25°C. Plant water status was also determined in the pre-harvest period. Irrigation treatments consisted of a control irrigated at 100% of crop evapotranspiration throughout the season, and two deficit irrigation treatments irrigated during the fruit growth period to maintain the ratio between the fruit growth rate (FGR) of the control trees and those of the water deficit treatment (signal intensity, SIFGR) at two different water stress levels: (i) Severe (DI10) when this ratio was around 1.1 (SIFGR), and (ii) moderate (DI5) when it was around 1.05. The amount of water applied in DI10 and DI5 represented a reduction of 40% and 29%, respectively, compared with the control. No negative effects on the yield parameters studied were observed. During the second fruit growth stage, differences in stem water potential at midday of around 0.4 and 0.9MPa in DI5 and DI10 treatments, respectively, respect control promoted a significant decrease in FGR. Overall, both DI treatments improved fruit quality at harvest due to increased total soluble solids and juice proline content, fruit maintained their quality longer during storage than the control. Cold stored fruit of both DI treatments presented similar fruit hardness values but a higher juice proline content, total soluble solids and titratable acidity, and, as a consequence, a lower maturity index than the control. At the end of storage, DI fruit showed a thicker skin and lower commercial losses due to chilling injury. © 2013 Elsevier B.V.


Conesa M.R.,Technical University of Cartagena | de la Rosa J.M.,Technical University of Cartagena | Artes-Hernandez F.,UPCT | Dodd I.C.,Lancaster University | And 2 more authors.
Journal of the Science of Food and Agriculture | Year: 2015

BACKGROUND: In table grapes, berry firmness influences consumer acceptance so it is important to avoid berry shattering and dehydration during their post-harvest life. Since studies of irrigation effects on table grape quality are comparatively rare, sensory evaluation aimed to identify high-quality berries obtained under different deficit irrigation treatments. A 3-year study examined the effects of deficit irrigation strategies on some physical quality attributes at harvest, after 28 days of cold storage at 0 °C and after an additional shelf-life period of 3 days at 15 °C. Control vines were irrigated to ensure non-limiting water conditions (110% of crop evapo-transpiration), while both regulated deficit irrigation treatment (RDI) and partial root-zone drying (PRD) treatments applied 35% less water post-veraison. The null irrigation treatment (NI) only received natural precipitation (72% less water than control vines). RESULTS: Total yield and physical quality at harvest were not significantly affected by RDI or PRD. Only severe deficit (NI) decreased berry size, and this treatment had the most dehydrated berries and the worst sensory scores post-harvest. After cold storage, increased berry shattering of the PRD treatment was correlated with lower leaf xylem abscisic acid (ABA) concentration at the time of harvest. Overall quality, especially stem browning, determined the shelf-life, and longer storage duration tended to diminish treatment differences. CONCLUSIONS: Only NI clusters showed lower quality than their irrigated counterparts. Neither RDI nor PRD had any noticeable effect on berry quality at the end of cold storage and shelf-life, with the slight differences detected between these treatments related to stem browning and dehydration. Sensory results were similar in RDI and PRD, which provided grapes that were more acceptable to consumers than the control. Thus, it is possible to decrease irrigation of table grapes without adversely affecting the physical quality of the berries. © 2015 Society of Chemical Industry.


Conesa M.R.,Technical University of Cartagena | Torres R.,UPCT | Domingo R.,Technical University of Cartagena | Navarro H.,UPCT | And 2 more authors.
Agricultural Water Management | Year: 2016

A two-year experiment was conducted to investigate the suitability of reference lines for irrigation scheduling based on maximum daily trunk shrinkage (MDS) and midday stem water potential (Ψs) in a commercial orchard of table grape cv. Crimson Seedless grafted onto Paulsen 1103 (V. berlandieri R. × V. rupestres du Lot). Vines were irrigated (from April to October) above their full crop water requirements (110% of crop evapotranspiration, ETc) in order to obtain non-limiting soil water conditions. The reference equations obtained for MDS and Ψs with meteorological factors differed between the pre and post-veraison periods. Before veraison, MDS was the most reliable indicator for assessing the water status of vines, whereas Ψs correlated better with meteorological variables after veraison. The sensitivity of MDS to ascertain the plant water status decreased during post-veraison due to its dependence on growth and to daily fluctuation of stem diameter. Moreover, it can also be induced by changes in the transpiration and also on the accumulation of xylem abscisic acid ([ABA]xylem). Mean temperature (Tm) was the environmental variable that best correlated with MDS and Ψs at pre-veraison. However, post-veraison reference lines can be obtained for MDS and Ψs using reference evapotranspiration (ET0) and mean daily vapour pressure deficit (VPDm). The use of MDS signal intensity (SIMDS) around the unity and Ψs around -0.65 MPa were the best criteria for irrigation scheduling in well-irrigated 'Crimson Seedless' table grapes growing in a semiarid climate of south-eastern Spain, during pre and post-veraison periods, respectively. © 2016 Elsevier B.V.


PubMed | UPCT, Technical University of Cartagena and Lancaster University
Type: Journal Article | Journal: Journal of the science of food and agriculture | Year: 2015

In table grapes, berry firmness influences consumer acceptance so it is important to avoid berry shattering and dehydration during their post-harvest life. Since studies of irrigation effects on table grape quality are comparatively rare, sensory evaluation aimed to identify high-quality berries obtained under different deficit irrigation treatments. A 3-year study examined the effects of deficit irrigation strategies on some physical quality attributes at harvest, after 28 days of cold storage at 0 C and after an additional shelf-life period of 3 days at 15 C. Control vines were irrigated to ensure non-limiting water conditions (110% of crop evapo-transpiration), while both regulated deficit irrigation treatment (RDI) and partial root-zone drying (PRD) treatments applied 35% less water post-veraison. The null irrigation treatment (NI) only received natural precipitation (72% less water than control vines).Total yield and physical quality at harvest were not significantly affected by RDI or PRD. Only severe deficit (NI) decreased berry size, and this treatment had the most dehydrated berries and the worst sensory scores post-harvest. After cold storage, increased berry shattering of the PRD treatment was correlated with lower leaf xylem abscisic acid (ABA) concentration at the time of harvest. Overall quality, especially stem browning, determined the shelf-life, and longer storage duration tended to diminish treatment differences.Only NI clusters showed lower quality than their irrigated counterparts. Neither RDI nor PRD had any noticeable effect on berry quality at the end of cold storage and shelf-life, with the slight differences detected between these treatments related to stem browning and dehydration. Sensory results were similar in RDI and PRD, which provided grapes that were more acceptable to consumers than the control. Thus, it is possible to decrease irrigation of table grapes without adversely affecting the physical quality of the berries.

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