Geothermal systems simulation: A case study

Geothermal reservoir simulation is a key step for developing sustainable and efficient strategies for the exploitation of geothermal resources. It is applied in the assessment of several areas of reservoir engineering, such as reservoir performance and re-injection programs, pressure decline in depletion, phase transition conditions, and natural evolution of hydrothermal convection systems. Fluid flow and heat transfer in rock masses, fluid-rock chemical interaction and rock mass deformation are some of the processes addressed in reservoir modelling. The case study of the Las Tres Virgenes (LTV) geothermal field (10 MWe), Baja California Sur, Mexico is presented. Three dimensional (3D) natural state simulations were carried out from emplacement and cooling of two spherical magma chambers using a conductive approach. A conceptual model of the volcanic system was developed on a lithostratigraphic and geochronological basis. Magma chamber volumes were established from eruptive volumes estimations. The thermophysical properties of the medium were assumed to correspond to the dominant rock in each lithological unit as an initial value, and further calibration was made considering histograms of experimentally obtained thermophysical properties of rocks. As the boundaries of the model lie far from the thermal anomaly, we assumed specified temperature boundaries. A Finite Volume (FV) numerical scheme was implemented in a Fortran 90 code to solve the heat equation. Static formation temperatures from well logs were used for validation of the numerical results. Good agreement was observed in those geothermal wells dominated by conductive heat transfer. For other wells, however, it is clear that conduction alone cannot explain observed behaviour, three-dimensional convective models are being implemented for future multiphysics simulations

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Evaluation of reproductive success in Senecio coincyi Rouy, a threatened species from Spain

Senecio coincyi Rouy (Asteraceae) is a threatened endemic species from the mountains of Sierra de Gredos, centraf western Spain. This species is protected by the Autonomous Community of Castile and León (Spain) and is included in the "In danger of extinction" category in the protected flora catalogue of that region. It was later catalogued as Vulnerable (VU) on the Red List of Threatened Spanish Vascular Flora (Moreno et al., 2008). In this paper, the results of a two-year investigation of S. coincyi population biology are shown. The aim of this work was to study several aspects of S. coincyi reproductive biology

Available Bandwidth Estimation Tools Metrics, Approaches and Performance

The estimation of the available bandwidth (av_bw) between two end nodes through the Internet, is an area that has motivated researchers around the world in the last twenty years, to have faster and more accurate tools; Due to the utility it has in various network applications; Such as routing management, intrusion detection systems and the performance of transport protocols. Different tools use different estimation techniques but generally only analyze the three most used metrics as av_bw, relative error and estimation time. This work expands the information regarding the evaluation literature of the current Available Bandwidth Estimation Tools (ABET's), where they analyze the estimation techniques, metrics, different generation tools of cross-traffic and evaluation testbed; Concentrating on the techniques and estimation methodologies used, as well as the challenges faced by open-source tools in high-performance networks of 10 Gbps or higher

Seed production and germination of the endangered species Astragalus gines-lopezii

Astragalus gines-lopeziiTalavera era/. {Fabaceae} is an endemic species from southwest Spain with a very limited area of distribution. There are only two known populations of this species, totaling less than 1000 individuals. This species was included on the Red List of Threatened Spanish Vascular Flora in 2008 in the category Endangered (EN) (Moreno 2008). The restricted area of distribution, limited number of individuals and their population structure could represent a high risk for survival of this species. Therefore, in order to detect potential threats, we have studied some key aspects of its reproductive biology. Fructification success and seed production were evaluated, and morphological and physiological seed variability were also studied

Modified procedure to assess dna breakage in spermatozoa by means of the comet assay

The comet assay is a relatively inexpensive, fast, sensitive and reliable method to detect DNA breakage upon individual cells. The most widely used cell type in this technique is lymphocyte, because they are easy to obtain and handle, and because they are continually exposed to xenobiotics that enter into the body. However, is important to consider the possibility to use other cell types for very specific purposes. Sperm cells are of special interest because they could be used as a biomonitor to risk assessment in populations occupationally exposed to xenobiotics. Besides, the fact that there are not functional DNA repair mechanisms in these cells could increase the sensitivity of the system. We present here several modifications to the comet assay methodology to evaluate DNA breakage in sperm cells with reliable results