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  • 1
    Publication Date: 2014-12-12
    Description: The dynamics of the magnetic relaxation process during the sustainment of spheromak configurations at different helicity injection rates is studied. The three-dimensional activity is recovered using time-dependent resistive magnetohydrodynamic simulations. A cylindrical flux conserver with concentric electrodes is used to model configurations driven by a magnetized coaxial gun. Magnetic helicity is injected by tangential boundary flows. Different regimes of sustainment are identified and characterized in terms of the safety factor profile. The spatial and temporal behavior of fluctuations is described. The dynamo action is shown to be in close agreement with existing experimental data. These results are relevant to the design and operation of helicity injected devices, as well as to basic understanding of the plasma relaxation mechanism in quasi-steady state.
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
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  • 2
    Publication Date: 2019
    Description: It is widely accepted that the Mediterranean is an oligotrophic sea where winter mixing favors the proliferation of diatoms and high values of zooplanktonic biomass, mainly associated with the growth of copepods. Stratified conditions from mid-spring to late autumn are dominated by the picophytoplanktonic groups and the increment of cladoceran abundances. This general picture has important exceptions. A regionalization of the Mediterranean Sea can be established, distinguishing oligotrophic and mesotrophic areas and different blooming periods. The RADMED monitoring program covers a large area from the southwestern limit of the Mediterranean to the Catalan Sea. The analysis of phyto and zooplankton time series extending from 1992 to 2016 in some cases, and from 2007 to 2016 in others, have shown that the Spanish Mediterranean waters have differentiated areas and trophic regimes as a result of the existence of several fertilizing mechanisms which include winter mixing, tidal mixing in the Strait of Gibraltar, cyclonic circulation cells and frontal systems. The present work describes these different mechanisms acting on the Spanish Mediterranean waters, and also the potentiality of monitoring programs for providing statistics suitable for operational activities or the initialization/validation of ecological models.
    Electronic ISSN: 2073-4441
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 3
    Publication Date: 2014-08-16
    Description: The redistribution of alpha particles due to internal kink modes is studied. The exact particle trajectories in the total fields, equilibrium plus perturbation, are calculated. The equilibrium has circular cross section and the plasma parameters are similar to those expected in ITER. The alpha particles are initially distributed according to a slowing down distribution function and have energies between 18 keV and 3.5 MeV. The (1, 1), (2, 2), and (2, 1) modes are included and the effect of changing their amplitude and frequency is studied. When only the (1, 1) mode is included, the spreading of high energy ( E ≳ 1  MeV) alpha particles increases slowly with the energy and mode frequency. At lower energies, the redistribution is more sensitive to the mode frequency and particle energy. When a (2, 1) mode is added, the spreading increases significantly and particles can reach the edge of the plasma. Trapped particles are the most affected and the redistribution parameter can have maxima above 1 MeV, depending on the mode frequency. These results can have important implications for ash removal.
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
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  • 4
    Publication Date: 2018
    Description: The Cape of Gata region (southeast Spain) allocates the thermo-haline Almeria–Oran front (AOF), which separates two biogeographical zones, with a very irregular bathymetry, consisting of two canyons and seamounts in an area of 100 × 100 km. An interdisciplinary oceanographic sampling strategy allowed us to solve mesoscale processes including current–bathymetry interactions. Subsurface fertilizing processes and elevated chlorophyll a concentrations were found at the front, seamount, and submarine canyons, turning an apparently oligotrophic area into a rich one. According to a horizontal tracking simulation, the deep chlorophyll maximum (DCM) at the front is located above the pycnocline and travels fast offshore, transporting productivity from the fertilization process quickly from the region. The DCM at the seamount, in contrast, develops below the pycnocline and remains for almost three weeks in this area. In spite of the coastal marine protected areas (MPAs), a high surface nitrate concentration plume with its origin in a small coastal area without any protection was detected. Local circulation patterns and bathymetry–current interactions provide elevated productivity in surface water which is vertically connected to deep-sea fauna via the daily vertical migration of zooplankton, suggesting elevated biodiversity on the seamount and canyons of the area studied. Based on these results, and considering the presence of coastal MPAs and a Coastal Area Management Program, future studies on benthic fauna, an enlargement of coastal MPAs, and a transboundary land–deep-sea management program are suggested.
    Electronic ISSN: 2073-4441
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 5
    Publication Date: 2018
    Description: In 1998, the plant breeding team at the School of Engineering of Orihuela (EPSO), part of the Miguel Hernández University (UMH) in Elche, commenced a tomato breeding program. Marker-assisted selection and backcrossing were used to simultaneously introduce three genes (Tm-2a, Ty-1, and Sw-5) that confer resistance to relevant viruses, such as tomato mosaic virus (ToMV), tomato yellow curl virus (TYLCV), and tomato spotted wilt virus (TSWV), to traditional varieties of local tomatoes, specifically the “Muchamiel” and the “De la pera” types. After each backcross, cleaved amplified polymorphic sequence (CAPS) molecular markers were used to select the plants with the resistance genes of interest. A previously described marker was used for TSWV, and new markers were designed for ToMV, and TYLCV using available sequences in the National Center for Biotechnology Information (NCBI) database. In parallel to the breeding program, several molecular markers—Sequence Related Amplified Polymorphism (SRAP), Simple Sequence Repeats (SSRs), Amplified Fragment Length Polymorphisms (AFLPs), Single Nucleotide Polymorphisms (SNPs), and (GATA)4 probes—were used to study genetic variability, and to identify a collection of Spanish and Italian traditional tomato varieties. The results showed a limited genetic variability among cultivated tomato varieties. The breeding lines Muchamiel UMH 1200, and De la pera 1203 (both with homozygous resistance to the three viruses) were the first new varieties that were obtained. They were included in the Register of Protected Plant Varieties in 2013. Lines without a resistance to TYLCV were also developed, and protected in 2017. We have begun to use SNP massive genotyping for studies of genetic association, and for selecting plants with the Ty-1 gene with less linkage drag. Molecular markers have been extremely useful in identifying the different steps of the tomato breeding program at EPSO-UMH.
    Electronic ISSN: 1424-2818
    Topics: Biology
    Published by MDPI
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  • 6
    Publication Date: 2018
    Description: The present work explores the biodegradation of some emerging pollutants (EPs) in an anaerobic slowly-agitated up-flow packed-bed reactor (USPBR) filled with biological activated carbon (BAC). Chlorobenzene (CB) and 2,4-dichlorophenoxyacetic acid (2,4-D) were selected as volatile organic compounds (VOC) and major constituents of many pesticides. Experiments carried out in continuous operation showed that bioconversion up to 90% was achieved for CB and 2,4-D, at space times below 0.6 h and 1.2 h, respectively, at ambient temperature. Overall, removal rates of 0.89 g L−1 d−1 and 0.46 g L−1 d−1 were obtained for CB and 2,4-D, respectively. These results revealed that the degradation of CB and 2,4-D in this anaerobic configuration of bioreactor is an efficient and fast process. The Michaelis–Menten model properly describes the degradation process for CB. Above initial concentrations of 100 mg L−1, 2,4-D presented a considerable inhibitory effect over the biofilm. For this reason, a substrate inhibition factor was included in the Michaelis–Menten equation; the expanded model presented a good fitting to the experimental data, regardless of the inlet concentration. Therefore, USPBR-BAC combination showed to be a highly efficient system for the biodegradation of such compounds.
    Electronic ISSN: 2076-3298
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 7
    Publication Date: 2019
    Description: (1) Background: The introduction of Information and communication technologies (ICTs) in the area of Physical Education is a very recent phenomenon, and its implementation is a challenge for teachers in Spain. It implies pedagogic innovation for the improvement of the teaching and learning processes, especially for people with a disability (functional diversity). The aim of this study was to identify the degree of technological knowledge (ICT) of the physical education teachers for students with disabilities. (2) Methods: A sample of 341 Physical Education teachers from Spain volunteered for this cross-sectional study. A questionnaire named “DIFOTICyD”, created “ad hoc” was used as the data-gathering instrument. (3) Results: the results revealed the low training of the participants with respect to the use of the ICTs in the field of disability. The degree of training of the teachers was determined by the personal (gender, age), professional (teaching experience) and educational (training received) outcomes. (4) Conclusions: the findings of the study point to the need for didactic training that can be used to train the Physical Education teachers to use ICTs in order to facilitate the learning and educational innovation of students with disabilities.
    Electronic ISSN: 2071-1050
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 8
    Publication Date: 2019
    Description: This study investigates distillery wastewater, commonly known as vinasse, as a potential culture medium for the production of Chlorella vulgaris and its most relevant metabolites. The effect of vinasse concentration on the composition of the biomass (proteins, carbohydrates, and lipids) was evaluated in treatments performed in 6-L tubular air-lift reactors. The reactors were operated at 25 °C for 18 days, in total darkness, under a continuous flow of air. Results showed a rapid growth of microalgae in the first ten days, when an average production of 0.87 g/L was reached. Then, the daily biomass productivity began to decrease, up to an average value of 11.8 g/L at the 16th day. For all treatments, there was a significant reduction in the concentration of most metabolites in the first eight days. This was likely due to the adaptation of the biomass to the new conditions, with a transition from autotrophic to heterotrophic metabolism. From the 10th day, the concentration of metabolites in the biomass began to increase, reaching a nearly constant value at the 16th day. The observed maximum concentrations (%w/w) were: 48.95% proteins, 2.88% xylose, 7.82% glucose, 4.54% arabinose, 8.28% fructose, and 4.82% lipids. These values were only marginally affected by the type of treatment. Overall, the results obtained suggest that vinasse is a promising and sustainable medium for the growth of C. vulgaris and the production of valuable metabolites.
    Electronic ISSN: 2073-4441
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 9
    Publication Date: 2019
    Description: Titanium is one of the most interesting materials in modern manufacturing thanks to its good mechanical properties and light weight. These features make it very attractive for use in the aeronautical and aerospace industries. Important alloys, such as Ti6Al4V, are extensively used. Nevertheless, titanium alloys present several problems in machining processes. Their machinability is poor, affected by low thermal conductivity, which generates very high cutting temperatures and thermal gradients in the cutting tool. Lubricants and cutting fluids have traditionally been used to solve this problem. However, this option is unsustainable as such lubricants represent a risk to the environment and to the health of the operator due to their different chemical components. Therefore, novel, sustainable and green lubrication techniques are necessary. Dry machining is the most sustainable option. Nevertheless, difficult-to-machine materials like titanium alloys cannot be machined under these conditions, leading to very high cutting temperatures and excessive tool wear. This study is intended to describe, analyse and review the non-traditional lubrication techniques developed in turning, drilling and milling processes since 2015, including minimum quantity of lubricant, cryogenic lubrication, minimum quantity of cooling lubrication or high-pressure coolant. The aim is to provide a general overview of the recent advances in each technique for the main machining processes.
    Electronic ISSN: 1996-1944
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by MDPI
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