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Sample records for hydrothermal convection systems

  1. Inversion Approach For Thermal Data From A Convecting Hydrothermal System

    Energy Technology Data Exchange (ETDEWEB)

    Kasameyer, P.; Younker, L.; Hanson, J.

    1985-01-01

    Hydrothermal systems are often studied by collecting thermal gradient data and temperature depth curves. These data contain important information about the flow field, the evolution of the hydrothermal system, and the location and nature of the ultimate heat sources. Thermal data are conventionally interpreted by the ''forward'' method; the thermal field is calculated based on selected initial conditions and boundary conditions such as temperature and permeability distributions. If the calculated thermal field matches the data, the chosen conditions are inferred to be possibly correct. Because many sets of initial conditions may produce similar thermal fields, users of the ''forward'' method may inadvertently miss the correct set of initial conditions. Analytical methods for ''inverting'' data also allow the determination of all the possible solutions consistent with the definition of the problem. In this paper we suggest an approach for inverting thermal data from a hydrothermal system, and compare it to the more conventional approach. We illustrate the difference in the methods by comparing their application to the Salton Sea Geothermal Field by Lau (1980a) and Kasameyer, et al. (1984). In this particular example, the inverse method was used to draw conclusions about the age and total rate of fluid flow into the hydrothermal system.

  2. Inversion approach for thermal data from a convecting hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Kasameyer, P.; Younker, L.; Hanson, J.

    1983-08-01

    Efforts to invert thermal data from 13 deep geothermal wells, and from additional shallow heat-flow holes, in order to determine the age and total flow rate of the Salton Sea hydrothermal system are described. The data were inverted for a very restrictive model: single-phase, horizontal flow along prescribed flowlines in a single aquifer bounded by an impermeable cap and base. With simplifying assumptions, the results are shown to depend on only two parameters, the system age, and the aquifer/cap thickness ratio. The surface gradient and temperature distribution within the cap are calculated analytically for all possible parameter values. Those parameters producing temperatures that agree with observations are identified, and the range of acceptable parameters is reduced by conclusions drawn from other geophysical data. The cap thickness is inferred to be 500m from thermal and lithologic data from the wells. The aquifer thickness is limited to less than 2500m by seismic, resistivity and magnetic data. It is concluded that if this model is valid, the system age is constrained between 3000 and 20,000 years.

  3. Chaotic thermohaline convection in low-porosity hydrothermal systems

    NARCIS (Netherlands)

    Schoofs, Stan; Spera, Frank J.; Hansen, Ulrich

    1999-01-01

    Fluids circulate through the Earth's crust perhaps down to depths as great as 5^15 km, based on oxygen isotope systematics of exhumed metamorphic terrains, geothermal fields, mesozonal batholithic rocks and analysis of obducted ophiolites. Hydrothermal flows are driven by both thermal and chemical

  4. Selected geothermal resources data: hydrothermal convection systems in the states of Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Renner, J.L.

    1976-02-01

    Data collected as part of the U.S. Geological Survey's research and land classification programs, from professional publications, and industry sources has been compiled in computer format. Location, surface manifestations, chemistry, physical properties, exploratory and development work, and references pertinent to 290 hydrothermal convection systems comprise the data base.

  5. hydrothermal systems

    Directory of Open Access Journals (Sweden)

    L. Bayón

    2002-01-01

    Full Text Available In this paper, we revise the classical formulation of the problem depriving it of the concepts that are superfluous from the mathematical point of view. We observe that a number of power stations can be substituted by a single one that behaves equivalently to the entire set. Proceeding in this way, we obtain a variational formulation in its purest sense (without restrictions. This formulation allows us to employ the theory of calculus of variations to the highest degree. We then calculate the equivalent minimizer in the case where the cost functions are second-order polynomials. We prove that the equivalent minimizer is a second-order polynomial with piece-wise constant coefficients. Moreover, it belongs to the class C1. Finally, we present various examples prompted by real systems and perform the proposed algorithms using Mathematica.

  6. Selected data for hydrothermal-convection systems in the United States with estimated temperatures greater than or equal to 90/sup 0/C: back-up data for US Geological Survey Circular 790

    Energy Technology Data Exchange (ETDEWEB)

    Mariner, R.H.; Brook, C.A.; Swanson, J.R.; Mabey, D.R.

    1978-12-01

    A compilation of data used in determining the accessible resource base for identified hydrothermal convection systems greater than or equal to 90/sup 0/C in the United States are presented. Geographic, geologic, chemical, isotopic, volumetric, and bibliographic data and calculated thermal energy contents are listed for all vapor-dominated and hot-water systems with estimated reservoir temperatures greater than or equal to 90/sup 0/C and reservoir depths less than 3 km known to the authors in mid 1978. Data presented here is stored in the US Geological Survey's geothermal computer file GEOTHERM. Data for individual hydrothermal convection systems in each state are arranged geographically from north to south and west to east without regard to the type or temperature of the system. Locations of the systems and corresponding reference numbers are shown on map 1 accompanying US Geological Survey Circular 790.

  7. Hydrothermal convection and uranium deposits in abnormally radioactive plutons

    International Nuclear Information System (INIS)

    1978-09-01

    Hydrothermal uranium deposits are often closely associated with granites of abnormally high uranium content. We have studied the question whether the heat generated within such granites can cause fluid convection of sufficient magnitude to develop hydrothermal uranium deposits. Numerical models of flow through porous media were used to calculate temperatures and fluid flow in and around plutons similar to the Conway Granite, New Hampshire, i.e. with a halfwidth of 17 km, a thickness of 6.25 km, and with a uniform internal heat generation rate of 20 x 10 -13 cal/cm 3 -sec. Fluid convection was computed for plutons with permeabilities between 0.01 and 5 millidarcies (1 x10 -13 cm 2 to 5 x 10 -11 cm 2 . Flow rates and the size and location of convection cells in and around radioactive plutons like the Conway Granite were found to depend critically on the permeability distribution within the pluton and in adjacent country rocks. The depth of burial, the distribution of heat sources within the pluton, and small rates of heat generation in the country rock are only of minor importance. Topographic relief is unlikely to effect flow rates significantly, but can have a major influence on the distribution of recharge and discharge areas. Within a few million years, the mass of water transported by steady state convection through such radioactive plutons can equal the mass of water which can convect through them during initial cooling from magmatic temperatures. If the permeability in a Conway-type pluton is on the order of 0.5 millidarcies, the rate of fluid convection is probably sufficient to develop a hydrothermal ore deposit containing 10,000 tons of uranium in a period of two million years. Such a uranium deposit is most likely to develop in an area of strong upwelling or strong downwelling flow

  8. Evenly-spaced columns in the Bishop Tuff as relicts of hydrothermal convection

    Science.gov (United States)

    Randolph-Flagg, N. G.; Breen, S. J.; Hernandez, A.; Self, S.; Manga, M.

    2015-12-01

    A few square km of the Bishop Tuff in eastern California, USA have evenly spaced erosional columns. These columns are more resistant to erosion due to the precipitation of the low-temperature zeolite (120-200 ºC), mordenite, which is not found in the surrounding tuff. Similar features observed in the Bandelier Tuff were hypothesized to form when cold water from above infiltrated into the still-hot tuff interior. This water would become gravitationally unstable and produced convection with steam upwellings and liquid water downwellings. These downwellings became cemented with mordenite while the upwellings were too dry for chemical reactions. We use two methods to quantitatively assess this hypothesis. First, scaling that ignores the effects of latent heat and mineral precipitation suggests the Rayleigh number (Ra, a measure of convective vigor) for this system is ~103 well above the critical Ra of 4π2. Second, to account for the effect of multiphase flow and latent heat, we use two-dimensional numerical models in the finite difference code HYDROTHERM. We find that the geometry of flow is consistent with field observations and confirm that geometry is sensitive to permeability and topography. These tests suggest a few things about low-pressure hydrothermal systems. 1) The geometry of at least some convection appears to be broadly captured by linear stability theory that ignores reactive transport, heterogeneity of host rock, and the effects of latent heat. 2) Topographic flow sets the wavelength of convection meaning that these columns formed somewhere without topography—probably a lake. Finally, these observations imply a wet paleoclimate in the Eastern Sierra namely that, in the aftermath of the Long Valley eruption, either rain or snow was able to pool in the caldera before the tuff cooled on the order of a hundred years after the eruption.

  9. Hydrothermal systems and volcano geochemistry

    Science.gov (United States)

    Fournier, R.O.

    2007-01-01

    The upward intrusion of magma from deeper to shallower levels beneath volcanoes obviously plays an important role in their surface deformation. This chapter will examine less obvious roles that hydrothermal processes might play in volcanic deformation. Emphasis will be placed on the effect that the transition from brittle to plastic behavior of rocks is likely to have on magma degassing and hydrothermal processes, and on the likely chemical variations in brine and gas compositions that occur as a result of movement of aqueous-rich fluids from plastic into brittle rock at different depths. To a great extent, the model of hydrothermal processes in sub-volcanic systems that is presented here is inferential, based in part on information obtained from deep drilling for geothermal resources, and in part on the study of ore deposits that are thought to have formed in volcanic and shallow plutonic environments.

  10. Hydrothermal, multiphase convection of H2O-NaCl fluids from ambient to magmatic temperatures : A new numerical scheme and benchmarks for code comparison

    NARCIS (Netherlands)

    Weis, P.; Driesner, T.; Coumou, D.; Geiger, S.

    2014-01-01

    Thermohaline convection of subsurface fluids strongly influences heat and mass fluxes within the Earth's crust. The most effective hydrothermal systems develop in the vicinity of magmatic activity and can be important for geothermal energy production and ore formation. As most parts of these systems

  11. Entropy production in a box: Analysis of instabilities in confined hydrothermal systems

    Science.gov (United States)

    Börsing, N.; Wellmann, J. F.; Niederau, J.; Regenauer-Lieb, K.

    2017-09-01

    We evaluate if the concept of thermal entropy production can be used as a measure to characterize hydrothermal convection in a confined porous medium as a valuable, thermodynamically motivated addition to the standard Rayleigh number analysis. Entropy production has been used widely in the field of mechanical and chemical engineering as a way to characterize the thermodynamic state and irreversibility of an investigated system. Pioneering studies have since adapted these concepts to natural systems, and we apply this measure here to investigate the specific case of hydrothermal convection in a "box-shaped" confined porous medium, as a simplified analog for, e.g., hydrothermal convection in deep geothermal aquifers. We perform various detailed numerical experiments to assess the response of the convective system to changing boundary conditions or domain aspect ratios, and then determine the resulting entropy production for each experiment. In systems close to the critical Rayleigh number, we derive results that are in accordance to the analytically derived predictions. At higher Rayleigh numbers, however, we observe multiple possible convection modes, and the analysis of the integrated entropy production reveals distinct curves of entropy production that provide an insight into the hydrothermal behavior in the system, both for cases of homogeneous materials, as well as for heterogeneous spatial material distributions. We conclude that the average thermal entropy production characterizes the internal behavior of hydrothermal systems with a meaningful thermodynamic measure, and we expect that it can be useful for the investigation of convection systems in many similar hydrogeological and geophysical settings.

  12. Hydrothermal processes above the Yellowstone magma chamber: Large hydrothermal systems and large hydrothermal explosions

    Science.gov (United States)

    Morgan, L.A.; Shanks, W.C. Pat; Pierce, K.L.

    2009-01-01

    and vein-fi lling; and (5) areal dimensions of many large hydrothermal explosion craters in Yellowstone are similar to those of its active geyser basins and thermal areas. For Yellowstone, our knowledge of hydrothermal craters and ejecta is generally limited to after the Yellowstone Plateau emerged from beneath a late Pleistocene icecap that was roughly a kilometer thick. Large hydrothermal explosions may have occurred earlier as indicated by multiple episodes of cementation and brecciation commonly observed in hydrothermal ejecta clasts. Critical components for large, explosive hydrothermal systems include a watersaturated system at or near boiling temperatures and an interconnected system of well-developed joints and fractures along which hydrothermal fluids flow. Active deformation of the Yellowstone caldera, active faulting and moderate local seismicity, high heat flow, rapid changes in climate, and regional stresses are factors that have strong infl uences on the type of hydrothermal system developed. Ascending hydrothermal fluids flow along fractures that have developed in response to active caldera deformation and along edges of low-permeability rhyolitic lava flows. Alteration of the area affected, self-sealing leading to development of a caprock for the hydrothermal system, and dissolution of silica-rich rocks are additional factors that may constrain the distribution and development of hydrothermal fields. A partial lowpermeability layer that acts as a cap to the hydrothermal system may produce some over-pressurization, thought to be small in most systems. Any abrupt drop in pressure initiates steam fl ashing and is rapidly transmitted through interconnected fractures that result in a series of multiple large-scale explosions contributing to the excavation of a larger explosion crater. Similarities between the size and dimensions of large hydrothermal explosion craters and thermal fields in Yellowstone may indicate that catastrophic events which result in l

  13. Dynamics of the Yellowstone hydrothermal system

    Science.gov (United States)

    Hurwitz, Shaul; Lowenstern, Jacob B.

    2014-01-01

    The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a hydrothermal system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and hydrothermal explosion craters. The diverse chemical and isotopic compositions of waters and gases derive from mantle, crustal, and meteoric sources and extensive water-gas-rock interaction at variable pressures and temperatures. The thermal features are host to all domains of life that utilize diverse inorganic sources of energy for metabolism. The unique and exceptional features of the hydrothermal system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the hydrothermal system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of hydrothermal explosions and their relation to glacial cycles, defining possible links between hydrothermal activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive hydrothermal activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.

  14. Chemical environments of submarine hydrothermal systems

    Science.gov (United States)

    Shock, Everett L.

    1992-01-01

    Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such

  15. Modeling of the fault-controlled hydrothermal ore-forming systems

    International Nuclear Information System (INIS)

    Pek, A.A.; Malkovsky, V.I.

    1993-07-01

    A necessary precondition for the formation of hydrothermal ore deposits is a strong focusing of hydrothermal flow as fluids move from the fluid source to the site of ore deposition. The spatial distribution of hydrothermal deposits favors the concept that such fluid flow focusing is controlled, for the most part, by regional faults which provide a low resistance path for hydrothermal solutions. Results of electric analog simulations, analytical solutions, and computer simulations of the fluid flow, in a fault-controlled single-pass advective system, confirm this concept. The influence of the fluid flow focusing on the heat and mass transfer in a single-pass advective system was investigated for a simplified version of the metamorphic model for the genesis of greenstone-hosted gold deposits. The spatial distribution of ore mineralization, predicted by computer simulation, is in reasonable agreement with geological observations. Computer simulations of the fault-controlled thermoconvective system revealed a complex pattern of mixing hydrothermal solutions in the model, which also simulates the development of the modern hydrothermal systems on the ocean floor. The specific feature of the model considered, is the development under certain conditions of an intra-fault convective cell that operates essentially independently of the large scale circulation. These and other results obtained during the study indicate that modeling of natural fault-controlled hydrothermal systems is instructive for the analysis of transport processes in man-made hydrothermal systems that could develop in geologic high-level nuclear waste repositories

  16. Recrystallization Experiments of Pyrite From Circulating Hydrothermal Solution by Thermal Convection

    Science.gov (United States)

    Tanaka, K.; Isobe, H.

    2005-12-01

    Pyrite is one of the most common accessory minerals in many rocks and generally occurs in hydrothermal deposit. However, pyrite morphology and association with other sulfide minerals is not well known with respect to the solution condition, especially with the hydrothermal solution under circulation. In this study, recrystallization experiments of pyrite from circulating hydrothermal solution by thermal convection were carried out. A rectangular circuit (42.6 cm by 17.3 cm) of SUS316 pressure tubing with 5 mm in inner diameter was used as a reaction vessel. The volume of the circuit is approximately 24 ml. Long sides of the rectangular circuit were held to be 20 degrees inclination. One of the long sides was heated by an electric furnace. Solution in the circuit evaporates in the high temperature tubing and the vapor condenses in room temperature tubing. The solution backs to the bottom of the high temperature tubing. Thus, thermal convection of the solution produces circulation in the circuit. Starting material was filled in the high temperature tubing. The lower half was filled with mixture of 2 g of powdered natural pyrite and 4 g of quartz grains. The upper half was filled with quartz grains only. 9 ml of 5 mol/l NH4Cl solution was sealed in the circuit with the starting material. Temperature gradient of the sample was monitored by 6 thermocouples. Maximum temperature was controlled at 350°C. Experimental durations are 3, 5, 10 and 30 days. After the experiments, the run products are fixed with resin and cut every 2 cm. Thin sections of vertical cross-sections are made and observed by microscope and SEM. Tiny pyrite crystals occurred at the upper outside of the furnace, where temperature should be much lower than 200°C. In the lower half of the starting material, pyrite decomposed and pyrrhotite formed around pyrite grains. At higher temperature area, pyrite decomposition and pyrrhotite formation is remarkable. Circulating sulfur-bearing solution provided by

  17. Hydrothermal systems in small ocean planets.

    Science.gov (United States)

    Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael

    2007-12-01

    We examine means for driving hydrothermal activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of hydrothermal system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of hydrothermal activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive hydrothermal fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive hydrothermal circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1).

  18. Anhydrite precipitation in seafloor hydrothermal systems

    Science.gov (United States)

    Theissen-Krah, Sonja; Rüpke, Lars H.

    2016-04-01

    The composition and metal concentration of hydrothermal fluids venting at the seafloor is strongly temperature-dependent and fluids above 300°C are required to transport metals to the seafloor (Hannington et al. 2010). Ore-forming hydrothermal systems and high temperature vents in general are often associated with faults and fracture zones, i.e. zones of enhanced permeabilities that act as channels for the uprising hydrothermal fluid (Heinrich & Candela, 2014). Previous numerical models (Jupp and Schultz, 2000; Andersen et al. 2015) however have shown that high permeabilities tend to decrease fluid flow temperatures due to mixing with cold seawater and the resulting high fluid fluxes that lead to short residence times of the fluid near the heat source. A possible mechanism to reduce the permeability and thereby to focus high temperature fluid flow are mineral precipitation reactions that clog the pore space. Anhydrite for example precipitates from seawater if it is heated to temperatures above ~150°C or due to mixing of seawater with hydrothermal fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of hydrothermal circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the hydrothermal flow field as well as the resulting vent temperatures. C. Andersen et al. (2015), Fault geometry and permeability contrast control vent temperatures at the Logatchev 1 hydrothermal field, Mid-Atlantic Ridge, Geology, 43(1), 51-54. M. D. Hannington et al. (2010), Modern Sea-Floor Massive Sulfides and Base Metal Resources: Toward an Estimate of Global Sea-Floor Massive Sulfide Potential, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, edited by R. J. Goldfarb, E. E. Marsh and T. Monecke, pp. 317-338, Society of Economic Geologists

  19. Boundary Layer Control of Rotating Convection Systems

    Science.gov (United States)

    King, E. M.; Stellmach, S.; Noir, J.; Hansen, U.; Aurnou, J. M.

    2008-12-01

    Rotating convection is ubiquitous in the natural universe, and is likely responsible for planetary processes such magnetic field generation. Rapidly rotating convection is typically organized by the Coriolis force into tall, thin, coherent convection columns which are aligned with the axis of rotation. This organizational effect of rotation is thought to be responsible for the strength and structure of magnetic fields generated by convecting planetary interiors. As thermal forcing is increased, the relative influence of rotation weakens, and fully three-dimensional convection can exist. It has long been assumed that rotational effects will dominate convection dynamics when the ratio of buoyancy to the Coriolis force, the convective Rossby number, Roc, is less than unity. We investigate the influence of rotation on turbulent Rayleigh-Benard convection via a suite of coupled laboratory and numerical experiments over a broad parameter range: Rayleigh number, 10310; Ekman number, 10-6≤ E ≤ ∞; and Prandtl number, 1≤ Pr ≤ 100. In particular, we measure heat transfer (as characterized by the Nusselt number, Nu) as a function of the Rayleigh number for several different Ekman and Prandtl numbers. Two distinct heat transfer scaling regimes are identified: non-rotating style heat transfer, Nu ~ Ra2/7, and quasigeostrophic style heat transfer, Nu~ Ra6/5. The transition between the non-rotating regime and the rotationally dominant regime is described as a function of the Ekman number, E. We show that the regime transition depends not on the global force balance Roc, but on the relative thicknesses of the thermal and Ekman boundary layers. The transition scaling provides a predictive criterion for the applicability of convection models to natural systems such as Earth's core.

  20. Porosity evolution in Icelandic hydrothermal systems

    Science.gov (United States)

    Thien, B.; Kosakowski, G.; Kulik, D. A.

    2014-12-01

    Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced hydrothermal systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems, grant number CRSII2_141843/1) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. These are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. These shallow plutons increase the geothermal gradient and trigger the circulation of hydrothermal waters with a steam cap forming at shallow depth. Field observations suggest that active and fossil Icelandic hydrothermal systems are built from a superposition of completely altered and completely unaltered layers. With help of 1D and 2D reactive transport models (OpenGeoSys-GEM code), we investigate the reasons for this finding, by studying the mineralogical evolution of protoliths with different initial porosities at different temperatures and pressures, different leaching water composition and gas content, and different porosity geometries (i.e. porous medium versus fractured medium). From this study, we believe that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are key factors to explain the different alteration extents observed in field studies. We also discuss how precipitation and dissolution kinetics can influence the alteration time scales.

  1. Presentation on Tropical Mesoscale convective Systems and ...

    Indian Academy of Sciences (India)

    IAS Admin

    Shallow convection- 70% of the storm heights are below 6 km. ♢ Deep convection ... Decay convection, the convective top is found at a higher altitude than deep .... Stratospheric Fountain – Two step process. Warm tropopause- preferable for.

  2. Combined hydrothermal liquefaction and catalytic hydrothermal gasification system and process for conversion of biomass feedstocks

    Science.gov (United States)

    Elliott, Douglas C.; Neuenschwander, Gary G.; Hart, Todd R.

    2017-09-12

    A combined hydrothermal liquefaction (HTL) and catalytic hydrothermal gasification (CHG) system and process are described that convert various biomass-containing sources into separable bio-oils and aqueous effluents that contain residual organics. Bio-oils may be converted to useful bio-based fuels and other chemical feedstocks. Residual organics in HTL aqueous effluents may be gasified and converted into medium-BTU product gases and directly used for process heating or to provide energy.

  3. Force convective solar drying system

    International Nuclear Information System (INIS)

    Ruslan, M.H.; Othman, M.Y.; Baharuddin Yatim; Kamaruzzaman Sopian; Ibarahim, Z.

    2006-01-01

    This paper presents design and performance of V-groove back-pass solar collector for solar drying system. In this study three V-groove back-pass solar collector each with dimension of 4.6 m x 1.0 m x 0.15 m have been fabricated for solar drying system. An outdoor test at mean solar intensity for 600-800 Wm -2 by using 0.15m 3 s -1 of air flow rate which also been suggested by (Zeroul et al. 1994) was carried out at Solar Research Energy Park. Universiti Kebangsaan Malaysia. Analysis on the collector performance based on daily data was reported that the value of FR ) e and FRUL was 0.709 ± 0.001 and 5.89 ± 0.31 Wm -2o C -1 respectively with 60-70 o C of output temperature (Ruslan et al. 2001). The three V-groove collectors each with dimension 4.6 m x 0.15 m were connected in series array mounted on the roof of a solar assisted drying system. By using two electric fans of 85W and 2700 rpm each, the speed of air was regulated at 0.11 kgs -1 to 0.31 kgs -1 using a voltage regulator. Performance of the collector based on the thermal analysis showed that at mean daily solar radiation 700 Wm -2 , the output temperature of 52 o C to 73 o C could be achieved using 0.11-0.31 kgs -1 of flow rate. Thermal analysis also showed that the efficiencies of 45% to 61% could be obtains using the same flow rate and solar radiation. Analysis of daily data showed that for radiation from 300 Wm -2 to 1000 Wm -2 the power generated from the collector was within 1.5 kW to 8.9 kW. The study concluded that the levels of the levels of the solar radiation and flow rate used influenced the performance of the collector

  4. thermal power stations' reliability evaluation in a hydrothermal system

    African Journals Online (AJOL)

    Dr Obe

    A quantitative tool for the evaluation of thermal power stations reliability in a hydrothermal system is presented. ... (solar power); wind (wind power) and the rest, thermal power and ... probability of a system performing its function adequately for ...

  5. Non-traditional Stable Isotope Systematics of Seafloor Hydrothermal Systems

    Science.gov (United States)

    Rouxel, O. J.

    2009-05-01

    Seafloor hydrothermal activity at mid-ocean ridges is one of the fundamental processes controlling the chemistry of the oceans and the altered oceanic crust. Past studies have demonstrated the complexity and diversity of seafloor hydrothermal systems and have highlighted the importance of subsurface environments in controlling the composition of hydrothermal fluids and mineralization types. Traditionally, the behavior of metals in seafloor hydrothermal systems have been investigated by integrating results from laboratory studies, theoretical models, mineralogy and fluid and mineral chemistry. Isotope ratios of various metals and metalloids, such as Fe, Cu, Zn, Se, Cd and Sb have recently provided new approaches for the study of seafloor hydrothermal systems. Despite these initial investigations, the cause of the isotopic variability of these elements remains poorly constrained. We have little understanding of the isotope variations between vent types (black or white smokers) as well as the influence of source rock composition (basalt, felsic or ultrabasic rocks) and alteration types. Here, I will review and present new results of metal isotope systematics of seafloor hydrothermal systems, in particular: (1) determination of empirical isotope fractionation factors for Zn, Fe and Cu-isotopes through isotopic analysis of mono-mineralic sulfide grains lining the internal chimney wall in contact with hydrothermal fluid; (2) comparison of Fe- and Cu-isotope signatures of vent fluids from mid- oceanic and back-arc hydrothermal fields, spanning wide ranges of pH, temperature, metal concentrations and contributions of magmatic fluids enriched in SO2. Ultimately, the use of complementary non-traditional stable isotope systems may help identify and constrain the complex interactions between fluids,minerals, and organisms in seafloor hydrothermal systems.

  6. Radionuclides in hydrothermal systems as indicators of repository conditions

    International Nuclear Information System (INIS)

    Wollenberg, H.A.; Flexser, S.; Smith, A.R.

    1990-11-01

    Hydrothermal systems in tuffaceous and older sedimentary rocks contain evidence of the interaction of radionuclides in fluids with rock matrix minerals and with materials lining fractures, in settings somewhat analogous to the candidate repository site at Yucca Mountain, NV. Earlier studies encompassed the occurrences of U and Th in a ''fossil'' hydrothermal system in tuffaceous rock of the San Juan Mountains volcanic field, CO. More recent and ongoing studies examine active hydrothermal systems in calderas at Long Valley, CA and Valles, NM. At the Nevada Test Site, occurrences of U and Th in fractured and unfractured rhyolitic tuff that was heated to simulate the introduction of radioactive waste are also under investigation. Observations to date suggest that U is mobile in hydrothermal systems, but that localized reducing environments provided by Fe-rich minerals and/or carbonaceous material concentrate U and thus attenuate its migration. 11 refs., 6 figs., 1 tab

  7. The hydrothermal evolution of the Kawerau geothermal system, New Zealand

    Science.gov (United States)

    Milicich, S. D.; Chambefort, I.; Wilson, C. J. N.; Charlier, B. L. A.; Tepley, F. J.

    2018-03-01

    Hydrothermal alteration zoning and processes provide insights into the evolution of heat source(s) and fluid compositions associated with geothermal systems. Traditional petrological techniques, combined with hydrothermal alteration studies, stable isotope analyses and geochronology can resolve the nature of the fluids involved in hydrothermal processes and their changes through time. We report here new findings along with previous unpublished works on alteration patterns, fluid inclusion measurements and stable isotope data to provide insights into the thermal and chemical evolution of the Kawerau geothermal system, New Zealand. These data indicate the presence of two hydrothermal events that can be coupled with chronological data. The earlier period of hydrothermal activity was initiated at 400 ka, with the heat driving the hydrothermal system inferred to be from the magmatic system that gave rise to rhyolite lavas and sills of the Caxton Formation. Isotopic data fingerprint fluids attributed to this event as meteoric, indicating that the magma primarily served as a heat source driving fluid circulation, and was not releasing magmatic fluids in sufficient quantity to affect the rock mineralogy and thus inferred fluid compositions. The modern Kawerau system was initiated at 16 ka with hydrothermal eruptions linked to shallow intrusion of magma at the onset of activity that gave rise to the Putauaki andesite cone. Likely associated with this later event was a pulse of magmatic CO2, resulting in large-scale deposition of hydrothermal calcite enriched in 18O. Meteoric water-dominated fluids subsequently overwhelmed the magmatic fluids associated with this 18O-rich signature, and both the fluid inclusion microthermometry and stable isotope data reflect a change to the present-day fluid chemistry of low salinity, meteoric-dominated waters.

  8. Numerical Simulation of a Non-volcanic Hydrothermal System Caused by Formation of a High Permeability Fracture Zone

    Science.gov (United States)

    Oka, Daisuke; Ehara, Sachio; Fujimitsu, Yasuhiro

    2010-05-01

    the beginning, convection occurs in the fracture zone when the fracture zone is formed. Then, the convection reaches to the quasi-steady state in the fracture zone. At the end, the larger convection evolves widely and slowly outside of the fracture zone. Therefore, it is inferred that a non-volcanic hydrothermal system will be formed after formation of a permeable fracture zone and the distributions of underground temperature and groundwater flow will change in the long term, even if no hydrothermal feature appears just after the seismic events.

  9. Fractionation of boron isotopes in Icelandic hydrothermal systems

    International Nuclear Information System (INIS)

    Aggarwal, J.K.

    1995-01-01

    Boron isotope ratios have been determined in a variety of different geothermal waters from hydrothermal systems across Iceland. Isotope ratios from the high temperature meteoric water recharged systems reflect the isotope ratio of the host rocks without any apparent fractionation. Seawater recharged geothermal systems exhibit more positive δ 1 1B values than the meteoric water recharged geothermal systems. Water/rock ratios can be assessed from boron isotope ratios in the saline hydrothermal systems. Low temperature hydrothermal systems also exhibit more positive δ 1 1B than the high temperature systems, indicating fractionation of boron due to absorption of the lighter isotope onto secondary minerals. Fractionation of boron in carbonate deposits may indicate the level of equilibrium attained within the systems. (author). 14 refs., 2 figs

  10. Land surface sensitivity of mesoscale convective systems

    Science.gov (United States)

    Tournay, Robert C.

    Mesoscale convective systems (MCSs) are important contributors to the hydrologic cycle in many regions of the world as well as major sources of severe weather. MCSs continue to challenge forecasters and researchers alike, arising from difficulties in understanding system initiation, propagation, and demise. One distinct type of MCS is that formed from individual convective cells initiated primarily by daytime heating over high terrain. This work is aimed at improving our understanding of the land surface sensitivity of this class of MCS in the contiguous United States. First, a climatology of mesoscale convective systems originating in the Rocky Mountains and adjacent high plains from Wyoming southward to New Mexico is developed through a combination of objective and subjective methods. This class of MCS is most important, in terms of total warm season precipitation, in the 500 to 1300m elevations of the Great Plains (GP) to the east in eastern Colorado to central Nebraska and northwest Kansas. Examining MCSs by longevity, short lasting MCSs (15 hrs) reveals that longer lasting systems tend to form further south and have a longer track with a more southerly track. The environment into which the MCS is moving showed differences across commonly used variables in convection forecasting, with some variables showing more favorable conditions throughout (convective inhibition, 0-6 km shear and 250 hPa wind speed) ahead of longer lasting MCSs. Other variables, such as convective available potential energy, showed improving conditions through time for longer lasting MCSs. Some variables showed no difference across longevity of MCS (precipitable water and large-scale vertical motion). From subsets of this MCS climatology, three regions of origin were chosen based on the presence of ridgelines extending eastward from the Rocky Mountains known to be foci for convection initiation and subsequent MCS formation: Southern Wyoming (Cheyenne Ridge), Colorado (Palmer divide) and

  11. Biosphere in 3.5 Ga submarine hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Yuichiro [Tokyo Univ. (Japan). Dept. of Earth Science and Astronomy

    2003-04-01

    Abundant organic matter (kerogen) was identified in {approx}3.5 Ga hydrothermal silica dikes from the North Pole area in the Pilbara craton, Western Australia. The silica dikes developed in the uppermost 1000 m of the ancient oceanic crust. Thus, they would have been deposited in the 3.5 Ga sub-seafloor hydrothermal system. The carbon and nitrogen isotopic compositions of the kerogen were analyzed in this study. Their highly {sup 13}C-depleted isotopic compositions ({delta}{sup 13}C = -38 to -33 per mille) strongly suggest that they are originally derived from biologically produced organic matter. The remarkable similarity of the {delta}{sup 13}C values between the kerogen and modern hydrothermal vent organisms may suggest that the kerogen was derived from chemoautotrophic organisms. This idea is also consistent with their nitrogen isotopic compositions ({delta}{sup 15}N = -4 to +4 per mille). The silica dikes consist mainly of fine-grained silica with minor pyrite and sphalerite. These mineral assemblages indicate that the silica dike was deposited from relatively low-temperature (probably less than 150degC) reducing hydrothermal fluid. Thus, anaerobic thermophilic/hyperthermophilic organisms could have survived in the hydrothermal fluid, which formed the silica dikes. Therefore, it is plausible that a chemoautotrophic-based biosphere (possibly methanogenesis) probably existed in the Early Archean sub-seafloor hydrothermal system. (author)

  12. The Interplay Between Saline Fluid Flow and Dynamic Permeability in Magmatic-Hydrothermal Systems

    Science.gov (United States)

    Weis, P.

    2014-12-01

    Magmatic-hydrothermal ore deposits document the interplay between saline fluid flow and rock permeability. Numerical simulations of multi-phase flow of variably miscible, compressible H20-NaCl fluids in concert with a dynamic permeability model can reproduce characteristics of porphyry copper and epithermal gold systems. This dynamic permeability model incorporates depth-dependent permeability profiles characteristic for tectonically active crust as well as pressure- and temperature-dependent relationships describing hydraulic fracturing and the transition from brittle to ductile rock behavior. In response to focused expulsion of magmatic fluids from a crystallizing upper crustal magma chamber, the hydrothermal system self-organizes into a hydrological divide, separating an inner part dominated by ascending magmatic fluids under near-lithostatic pressures from a surrounding outer part dominated by convection of colder meteoric fluids under near-hydrostatic pressures. This hydrological divide also provides a mechanism to transport magmatic salt through the crust, and prevents the hydrothermal system to become "clogged" by precipitation of solid halite due to depressurization of saline, high-temperature magmatic fluids. The same physical processes at similar permeability ranges, crustal depths and flow rates are relevant for a number of active systems, including geothermal resources and excess degassing at volcanos. The simulations further suggest that the described mechanism can separate the base of free convection in high-enthalpy geothermal systems from the magma chamber as a driving heat source by several kilometers in the vertical direction in tectonic settings with hydrous magmatism. This hydrology would be in contrast to settings with anhydrous magmatism, where the base of the geothermal systems may be closer to the magma chamber.

  13. Application of cultural algorithm to generation scheduling of hydrothermal systems

    International Nuclear Information System (INIS)

    Yuan Xiaohui; Yuan Yanbin

    2006-01-01

    The daily generation scheduling of hydrothermal power systems plays an important role in the operation of electric power systems for economics and security, which is a large scale dynamic non-linear constrained optimization problem. It is difficult to solve using traditional optimization methods. This paper proposes a new cultural algorithm to solve the optimal daily generation scheduling of hydrothermal power systems. The approach takes the water transport delay time between connected reservoirs into consideration and can conveniently deal with the complicated hydraulic coupling simultaneously. An example is used to verify the correctness and effectiveness of the proposed cultural algorithm, comparing with both the Lagrange method and the genetic algorithm method. The simulation results demonstrate that the proposed algorithm has rapid convergence speed and higher solution precision. Thus, an effective method is provided to solve the optimal daily generation scheduling of hydrothermal systems

  14. Geochemical constraints on chemolithoautotrophic reactions in hydrothermal systems

    Science.gov (United States)

    Shock, Everett L.; McCollom, Thomas; Schulte, Mitchell D.

    1995-06-01

    Thermodynamic calculations provide the means to quantify the chemical disequilibrium inherent in the mixing of redeuced hydrothermal fluids with seawater. The chemical energy available for metabolic processes in these environments can be evaluated by taking into account the pressure and temperature dependence of the apparent standard Gibbs free energies of reactions in the S-H2-H2O system together with geochemical constraints on pH, activities of aqueous sulfur species and fugacities of H2 and/or O2. Using present-day mixing of hydrothermal fluids and seawater as a starting point, it is shown that each mole of H2S entering seawater from hydrothermal fluids represents about 200,000 calories of chemical energy for metabolic systems able to catalyze H2S oxidation. Extrapolating to the early Earth, which was likely to have had an atmosphere more reduced than at present, shows that this chemical energy may have been a factor of two or so less. Nevertheless, mixing of hydrothermal fluids with seawater would have been an abundant source of chemical energy, and an inevitable consequence of the presence of an ocean on an initially hot Earth. The amount of energy available was more than enough for organic synthesis from CO2 or CO, and/or polymer formation, indicating that the vicinity of hydrothermal systems at the sea floor was an ideal location for the emergence of the first chemolithoautotrophic metabolic systems.

  15. Ignition in Convective-Diffusive Systems

    National Research Council Canada - National Science Library

    Law, Chung

    1999-01-01

    ... efficiency as well as the knock and emission characteristics. The ignition event is clearly controlled by the chemical reactions of fuel oxidation and the fluid mechanics of convective and diffusive transport...

  16. Hydrothermal systems on Mars: an assessment of present evidence

    Science.gov (United States)

    Farmer, J. D.

    1996-01-01

    Hydrothermal processes have been suggested to explain a number of observations for Mars, including D/H ratios of water extracted from Martian meteorites, as a means for removing CO2 from the Martian atmosphere and sequestering it in the crust as carbonates, and as a possible origin for iron oxide-rich spectral units on the floors of some rifted basins (chasmata). There are numerous examples of Martian channels formed by discharges of subsurface water near potential magmatic heat sources, and hydrothermal processes have also been proposed as a mechanism for aquifer recharge needed to sustain long term erosion of sapping channels. The following geological settings have been identified as targets for ancient hydrothermal systems on Mars: channels located along the margins of impact crater melt sheets and on the slopes of ancient volcanoes; chaotic and fretted terranes where shallow subsurface heat sources are thought to have interacted with ground ice; and the floors of calderas and rifted basins (e.g. chasmata). On Earth, such geological environments are often a locus for hydrothermal mineralization. But we presently lack the mineralogical information needed for a definitive evaluation of hypotheses. A preferred tool for identifying minerals by remote sensing methods on Earth is high spatial resolution, hyperspectral, near-infrared spectroscopy, a technique that has been extensively developed by mineral explorationists. Future efforts to explore Mars for ancient hydrothermal systems would benefit from the application of methods developed by the mining industry to look for similar deposits on Earth. But Earth-based exploration models must be adapted to account for the large differences in the climatic and geological history of Mars. For example, it is likely that the early surface environment of Mars was cool, perhaps consistently below freezing, with the shallow portions of hydrothermal systems being dominated by magma-cryosphere interactions. Given the smaller

  17. Chemistry of a serpentinization-controlled hydrothermal system at the Lost City hydrothermal vent field

    Science.gov (United States)

    Ludwig, K. A.; Kelley, D. S.; Butterfield, D. A.; Nelson, B. K.; Karson, J. A.

    2003-12-01

    The Lost City Hydrothermal Field (LCHF), at 30° N near the Mid-Atlantic Ridge, is an off-axis, low temperature, high-pH, ultramafic-hosted vent system. Within the field, carbonate chimneys tower up to 60 m above the seafloor, making them the tallest vent structures known. The chemistry of the vent structures and fluids at the LCHF is controlled by reactions between seawater and ultramafic rocks beneath the Atlantis massif. Mixing of warm alkaline vent fluids with seawater causes precipitation of calcium carbonate and growth of the edifaces, which range from tall, graceful pinnacles to fragile flanges and colloform deposits. Geochemical and petrological analyses of the carbonate rocks reveal distinct differences between the active and extinct structures. Actively venting chimneys and flanges are extremely porous, friable formations composed predominantly of aragonite and brucite. These structures provide important niches for well-developed microbial communities that thrive on and within the chimney walls. Some of the active chimneys may also contain the mineral ikaite, an unstable, hydrated form of calcium carbonate. TIMS and ICP-MS analyses of the carbonate chimneys show that the most active chimneys have low Sr isotope values and that they are low in trace metals (e.g., Mn, Ti, Pb). Active structures emit high-pH, low-Mg fluids at 40-90° C. The fluids also have low Sr values, indicating circulation of hydrothermal solutions through the serpentinite bedrock beneath the field. In contrast to the active structures, extinct chimneys are less porous, are well lithified, and they are composed predominantly of calcite that yields Sr isotopes near seawater values. Prolonged lower temperature seawater-hydrothermal fluid interaction within the chimneys results in the conversion of aragonite to calcite and in the enrichment of some trace metals (e.g., Mn, Ti, Co, Zn). It also promotes the incorporation of foraminifera within the outer, cemented walls of the carbonate

  18. Dynamic behavior of Kilauea Volcano and its relation to hydrothermal systems and geothermal energy

    Science.gov (United States)

    Kauhikaua, Jim; Moore, R.B.; ,

    1993-01-01

    Exploitation of hydrothermal systems on active basaltic volcanoes poses some unique questions about the role of volcanism and hydrothermal system evolution. Volcanic activity creates and maintains hydrothermal systems while earthquakes create permeable fractures that, at least temporarily, enhance circulation. Magma and water, possibly hydrothermal water, can interact violently to produce explosive eruptions. Finally, we speculate on whether volcanic behavior can be affected by high rates of heat extraction.

  19. Convective heat and mass transfer in rotating disk systems

    CERN Document Server

    Shevchuk, Igor V

    2009-01-01

    The book describes results of investigations of a series of convective heat and mass transfer problems in rotating-disk systems. Methodology used included integral methods, self-similar and approximate analytical solutions, as well as CFD.

  20. Hydrothermal Processes

    Science.gov (United States)

    German, C. R.; von Damm, K. L.

    2003-12-01

    What is Hydrothermal Circulation?Hydrothermal circulation occurs when seawater percolates downward through fractured ocean crust along the volcanic mid-ocean ridge (MOR) system. The seawater is first heated and then undergoes chemical modification through reaction with the host rock as it continues downward, reaching maximum temperatures that can exceed 400 °C. At these temperatures the fluids become extremely buoyant and rise rapidly back to the seafloor where they are expelled into the overlying water column. Seafloor hydrothermal circulation plays a significant role in the cycling of energy and mass between the solid earth and the oceans; the first identification of submarine hydrothermal venting and their accompanying chemosynthetically based communities in the late 1970s remains one of the most exciting discoveries in modern science. The existence of some form of hydrothermal circulation had been predicted almost as soon as the significance of ridges themselves was first recognized, with the emergence of plate tectonic theory. Magma wells up from the Earth's interior along "spreading centers" or "MORs" to produce fresh ocean crust at a rate of ˜20 km3 yr-1, forming new seafloor at a rate of ˜3.3 km2 yr-1 (Parsons, 1981; White et al., 1992). The young oceanic lithosphere formed in this way cools as it moves away from the ridge crest. Although much of this cooling occurs by upward conduction of heat through the lithosphere, early heat-flow studies quickly established that a significant proportion of the total heat flux must also occur via some additional convective process (Figure 1), i.e., through circulation of cold seawater within the upper ocean crust (Anderson and Silbeck, 1981). (2K)Figure 1. Oceanic heat flow versus age of ocean crust. Data from the Pacific, Atlantic, and Indian oceans, averaged over 2 Ma intervals (circles) depart from the theoretical cooling curve (solid line) indicating convective cooling of young ocean crust by circulating seawater

  1. Vertical Transport by Coastal Mesoscale Convective Systems

    Science.gov (United States)

    Lombardo, K.; Kading, T.

    2016-12-01

    This work is part of an ongoing investigation of coastal mesoscale convective systems (MCSs), including changes in vertical transport of boundary layer air by storms moving from inland to offshore. The density of a storm's cold pool versus that of the offshore marine atmospheric boundary layer (MABL), in part, determines the ability of the storm to successfully cross the coast, the mechanism driving storm propagation, and the ability of the storm to lift air from the boundary layer aloft. The ability of an MCS to overturn boundary layer air can be especially important over the eastern US seaboard, where warm season coastal MCSs are relatively common and where large coastal population centers generate concentrated regions of pollution. Recent work numerically simulating idealized MCSs in a coastal environment has provided some insight into the physical mechanisms governing MCS coastal crossing success and the impact on vertical transport of boundary layer air. Storms are simulated using a cloud resolving model initialized with atmospheric conditions representative of a Mid-Atlantic environment. Simulations are run in 2-D at 250 m horizontal resolution with a vertical resolution stretched from 100 m in the boundary layer to 250 m aloft. The left half of the 800 km domain is configured to represent land, while the right half is assigned as water. Sensitivity experiments are conducted to quantify the influence of varying MABL structure on MCS coastal crossing success and air transport, with MABL values representative of those observed over the western Mid-Atlantic during warm season. Preliminary results indicate that when the density of the cold pool is much greater than the MABL, the storm successfully crosses the coastline, with lifting of surface parcels, which ascend through the troposphere. When the density of the cold pool is similar to that of the MABL, parcels within the MABL remain at low levels, though parcels above the MABL ascend through the troposphere.

  2. Asymmetrical hydrothermal system below Merapi volcano imaged by geophysical data.

    Science.gov (United States)

    Byrdina, Svetlana; Friedel, Sven; Budi-Santoso, Agus; Suryanto, Wiwit; Suhari, Aldjarishy; Vandemeulebrouck, Jean; Rizal, Mohhamed H.; Grandis, Hendra

    2017-04-01

    A high-resolution image of the hydrothermal system of Merapi volcano is obtained using electrical resistivity tomography (ERT), self-potential, and CO2 flux mappings. The ERT inversions identify two distinct low-resistivity bodies, at the base of the south flank and in the summit area, that represent likely two parts of an interconnected hydrothermal system. In the summit area, the extension of the hydrothermal system is clearly limited by the main geological structures which are actual and ancient craters. A sharp resistivity contrast at ancient crater rim Pasar-Bubar separates a conductive hydrothermal system (20 - 50 Ωm) from the resistive andesite lava flows and pyroclastic deposits (2000 - 50 000 Ωm). High diffuse CO2 degassing (with a median value of 400g m -2 d -1) is observed in a narrow vicinity of the active crater rim and close to the Pasar-Bubar. The existence of preferential fluid circulation along this ancient crater rim is also evidenced by self-potential data. The total CO2 degassing across the accessible summit area with a surface of 1.4 · 10 5 m 2 is around 20 td -1. Before the 2010 eruption, Toutain et al. (2009) estimated a higher value of the total diffuse degassing from the summit area (about 200 - 230 td -1). This drop in the diffuse degassing can be related to the decrease in the magmatic activity, to the change of the summit morphology or to a combination of these factors. On the south flank of Merapi, the resistivity model shows spectacular stratification. While surficial recent andesite lava flows are characterized by resistivity exceeding 100 000 Ωm, resistivity as low as 10 Ωm has been encountered at a depth of 200 m at the base of the south flank and was interpreted as a presence of the hydrothermal system. We suggest that a sandwich-like structure of stratified pyroclastic deposits on the flanks of Merapi screen and separate the flow of hydrothermal fluids with the degassing occurring mostly through the fractured crater rims

  3. On the theory system of hydrothermal uranium metallization in China

    International Nuclear Information System (INIS)

    Du Letian

    2011-01-01

    Based on summarizing the mass of research outcome of the predecessors, the author attempts to make a brief generalization on the theory system of hydrothermal uranium mineralization in China. The system of uranium metallization is founded in the basic way of uranium source-migration-transportation-richment-reservation. The system mainly consists of the following frames: (1) mineralization type of silification zone; (2) age gap of mineralization to host rock; (3) alkli metasomatism; (4) metallogenic layer of crust; (5)integratation of 4 types mineralization (granite, volcanics, carbonaceous-siliceous-argilaceous rock and sandstone) in tectonic-hydrothermal process; (6) pre-enrichment process of metallization; (7) decouplement of granite magma evolution; (8) types of rich ore by high tempreture sericitization; (9)basalt event;(10) rock and ore formation by HARCON. (authors)

  4. Geophysical image of the hydrothermal system of Merapi volcano

    Science.gov (United States)

    Byrdina, S.; Friedel, S.; Vandemeulebrouck, J.; Budi-Santoso, A.; Suhari; Suryanto, W.; Rizal, M. H.; Winata, E.; Kusdaryanto

    2017-01-01

    We present an image of the hydrothermal system of Merapi volcano based on results from electrical resistivity tomography (ERT), self-potential, and CO2 flux mappings. The ERT models identify two distinct low-resistivity bodies interpreted as two parts of a probably interconnected hydrothermal system: at the base of the south flank and in the summit area. In the summit area, a sharp resistivity contrast at ancient crater rim Pasar-Bubar separates a conductive hydrothermal system (20-50 Ω m) from the resistive andesite lava flows and pyroclastic deposits (2000-50,000 Ω m). The existence of preferential fluid circulation along this ancient crater rim is also evidenced by self-potential data. The significative diffuse CO2 degassing (with a median value of 400 g m-2 d-1) is observed in a narrow vicinity of the active crater rim and close to the ancient rim of Pasar-Bubar. The total CO2 degassing across the accessible summital area with a surface of 1.4 ṡ 105 m2 is around 20 t d-1. Before the 2010 eruption, Toutain et al. (2009) estimated a higher value of the total diffuse degassing from the summit area (about 200-230 t d-1). This drop in the diffuse degassing from the summit area can be related to the decrease in the magmatic activity, to the change of the summit morphology, to the approximations used by Toutain et al. (2009), or, more likely, to a combination of these factors. On the south flank of Merapi, the resistivity model shows spectacular stratification. While surficial recent andesite lava flows are characterized by resistivity exceeding 100,000 Ω m, resistivity as low as 10 Ω m has been encountered at a depth of 200 m at the base of the south flank and was interpreted as a presence of the hydrothermal system. No evidence of the hydrothermal system is found on the basis of the north flank at the same depth. This asymmetry might be caused by the asymmetry of the heat supply source of Merapi whose activity is moving south or/and to the asymmetry in

  5. Hydrothermal alteration of Hercynian granites, its significance to the evolution of geothermal systems in granitic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Jose M.; Matias, Maria J.; Basto, Maria J.; Aires-Barros, Luis A. [Instituto Superior Tecnico, Centro de Petrologia e Geoquimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Carreira, Paula M. [Instituto Tecnologico e Nuclear, Estrada Nacional n 10, 2686 - 953 Sacavem (Portugal); Goff, Fraser E. [Earth and Planetary Sciences Department, Univ. of New Mexico, Albuquerque, NM 87131 (United States)

    2010-06-15

    We discuss geochemical and isotopic ({sup 18}O/{sup 16}O, {sup 2}H/{sup 1}H and {sup 87}Sr/{sup 86}Sr) data recording the hydrothermal alteration of northern Portuguese Hercynian granites by Na-HCO{sub 3}-CO{sub 2}-rich mineral waters. Whole-rock samples from drill cores of Vilarelho da Raia granite have {delta}{sup 18}O values in the +11.47 to +10.10 permille range. The lower values correspond to highly fractured granite samples displaying vein and pervasive alteration. In the pervasive alteration stage, which probably results from a convective hydrothermal system set up by the intrusion of the granites, the metamorphic waters are in equilibrium with hydrous minerals. In contrast, the vein alteration of these granitic rocks was caused by water of meteoric origin. The oxygen ratios between water (W) and rock (R), the so-called W/R ratios, obtained for the open system (where the heated water is lost from the system by escape to the surface) range between 0.05 and 0.11, suggesting that the recrystallization of the veins was influenced by a small flux of meteoric water. Stable isotope analyses performed on the cores show that the vein alteration stage relates to post-emplacement tectonic stresses acting on the granite, probably of late Hercynian age. Our results are consistent with the existence of two separate alteration events (pervasive and vein) caused by hydrothermal waters of different isotopic characteristics. The studies presented in this paper should be viewed as a natural analogue that uses the alteration features observed in a fossil geothermal system at Vilarelho da Raia to assess possible water-rock reactions presently occurring at depth in granitic rocks of the nearby Chaves area. (author)

  6. Presence of radionuclides in clays of the hydrothermal system of the Volcano Turrialba, Costa Rica

    International Nuclear Information System (INIS)

    Garcia-Vindas, J.R.; Gazel, Esteban

    2004-01-01

    The first results obtained about the presence of radionuclides of terrigenous origin in the hydrothermal system of Turrialba Volcano are shown in this paper. Several samples were taken in the central and southwest craters, and analyzed by gamma-ray spectrometry, with Hyper pure Germanium detector. The values of the activities of the natural radioactive isotopes are shown in Bq/kg. A disequilibrium in the series of U-238 was found, which is explained by two different mechanisms: one convective and the other by Rn-222 enrichment. An increase of the activity of all isotopes is observed between September 2001 and May 2002. Because the low possibilities that this can be produced by the water runoff, it is proposed that such rise in the concentration of the elements can be explained by their presence in the water vapour and other volcanic gases. (Author) [es

  7. Geochemical Constraints on Archaeal Diversity in the Vulcano Hydrothermal System

    Science.gov (United States)

    Rogers, K. L.; Amend, J. P.

    2006-12-01

    The shallow marine hydrothermal system of Vulcano, Italy hosts a wide diversity of cultured thermophilic Archaea, including Palaeococcus helgesonii, Archaeoglobus fulgidus, and Pyrococcus furiosus, to name a few. However, recent studies have revealed a plethora of uncultured archaeal lineages in the Vulcano system. For example, a 16S rRNA gene survey of an onshore geothermal well identified a diverse archaeal community including deeply-branching uncultured Crenarchaeota, Korarchaeota, and Euryarchaeota. Additionally, culture-independent hybridization techniques suggested that Archaea account for nearly half of the microbial community in the Vulcano system. Furthermore, geochemical characterization of fluids revealed numerous lithotrophic and heterotrophic exergonic reactions that could support as yet uncultured organisms. Archaeal diversity throughout the Vulcano hydrothermal system was investigated using 16S rRNA gene surveys at five submarine vents and an onshore sediment seep. Overall, archaeal diversity was higher (10 groups) at submarine vents with moderate temperatures (59°C) compared with higher temperature (94°C) vents (4 groups). Archaeal communities at the moderately thermal vents were dominated by Thermococcales and also contained Archaeoglobales, Thermoproteales, and uncultured archaea among the Korarchaeota, Marine Group I, and the Deep-sea Hydrothermal Vent Euryarchaeota (DHVE). Fluid composition also affects the microbial community structure. At two high-temperature sites variations in archaeal diversity can be attributed to differences in iron and hydrogen concentrations, and pH. Comparing sites with similar temperature and pH conditions suggests that the presence of Desulfurococcales is limited to sites at which metabolic energy yields exceed 10 kJ per mole of electrons transferred. The Vulcano hydrothermal system hosts diverse archaeal communities, containing both cultured and uncultured species, whose distribution appears to be constrained by

  8. Environmental Characteristics of Convective Systems During TRMM-LBA

    Science.gov (United States)

    Halverson, Jeffrey B.; Rickenbach, Thomas; Roy, Biswadev; Pierce, Harold; Williams, Earle; Einaudi, Franco (Technical Monitor)

    2001-01-01

    In this paper, data collected from 51 days of continual upper atmospheric soundings and TOGA radar at ABRACOS Hill during the TRMM-LBA experiment are used to describe the mean thermodynamic and kinematic airmass properties of wet season convection over Rondonia, Brazil. Distinct multi-day easterly and westerly lower tropospheric wind regimes occurred during the campaign with contrasting airmass characteristics. Westerly wind periods featured modest CAPE (1000 J/kg), moist conditions (>90% RH) extending through 700 mb and shallow (900 mb) speed shear on the order of 10(exp -4)/s. This combination of characteristics promoted convective systems that featured a relatively large fraction of stratiform rainfall and weak convection nearly devoid of lightning. The environment is very similar to the general airmass conditions experienced during the Darwin, Australia monsoon convective regime. In contrast, easterly regime convective systems were more strongly electrified and featured larger convective rain rates and reduced stratiform rainfall fraction. These systems formed in an environment with significantly larger CAPE (1500 J/kg), drier lower and middle level humidities (in the lowest 1-2 km, thus contributing to a more explosive growth of convection. The time series of low- and mid-level averaged humidity exhibited marked variability between westerly and easterly regimes and was characterized by low frequency (i.e., multi-day to weekly) oscillations. The synoptic scale origins of these moisture fluctuations are examined, which include the effects of variable low-level airmass trajectories and upper-level, westward migrating cyclonic vortices. The results reported herein provide an environmental context for ongoing dual Doppler analyses and numerical modeling case studies of individual TRMM-LBA convective systems.

  9. Isotopic study of some fossil and actual hydrothermal systems

    International Nuclear Information System (INIS)

    Demont, J.M.

    1981-07-01

    Oxygen and hydrogen isotopic compositions of rocks from the INAG no 1 drillhole provide evidence of a fossil hydrothermal system in the Ceyssat region of the Massif Central. Oxygen isotope temperatures for the mineral paragenesis are about 275 0 C and the water is of marine origin. Measurements have also been made of delta 13 C values of dissolved carbon and gaseous CO 2 from several hot springs in the Pyrenees and Massif Central. The carbon isotopic composition of the total systems have been calculated from the gas-liquid ratios at the emergence sites and these results are discussed in terms of the origin of the carbon. Most of the hydrothermal carbon is of deep origin. The observed variations in isotopic compositions may be explained by the behavior of the fluids during their ascent to the surface [fr

  10. The transport of oxygen isotopes in hydrothermal systems

    International Nuclear Information System (INIS)

    McKibbin, R.; Absar, A.; Blattner, P.

    1986-01-01

    As groundwater passes through porous rocks, exchange of oxygen between the fluid and the solid matrix causes a change in the oxygen isotope concentrations in both water and rock. If the rate at which the exchange takes place can be estimated (as a function of the isotope concentrations and temperature) then the time taken for a rock/water system to come to equilibrium with respect to isotope concentration might be calculated. In this paper, the equation for isotope transport is derived using conservation laws, and a simple equation to describe the rate of isotope exchange is proposed. These are combined with the equations for fluid flow in a porous medium, to produce a general set of equations describing isotope transport in a hydrothermal system. These equations are solved numerically, using typical parameters, for the one-dimensional case. Oxygen isotope data from the basement rocks underlying Kawerau geothermal field are modelled. The results indicate that the time taken for exchange of 18 O to present-day values is less than the postulated age of hydrothermal alteration in that field. This suggests that, although controlled by similar parameters, oxygen isotope exchange, in felsic rocks at least, is much faster than hydrothermal alteration. This conclusion is consistent with the petrographic observations from the Kawerau system as well as other geothermal fields

  11. Diffuse flow hydrothermal manganese mineralization along the active Mariana and southern Izu-Bonin arc system, western Pacific

    Science.gov (United States)

    Hein, J.R.; Schulz, M.S.; Dunham, R.E.; Stern, R.J.; Bloomer, S.H.

    2008-01-01

    Abundant ferromanganese oxides were collected along 1200 km of the active Izu-Bonin-Mariana arc system. Chemical compositions and mineralogy show that samples were collected from two deposit types: Fe-Mn crusts of mixed hydrogenetic/hydrothermal origin and hydrothermal Mn oxide deposits; this paper addresses only the second type. Mn oxides cement volcaniclastic and biogenic sandstone and breccia layers (Mn sandstone) and form discrete dense stratabound layers along bedding planes and within beds (stratabound Mn). The Mn oxide was deposited within coarse-grained sediments from diffuse flow systems where precipitation occurred below the seafloor. Deposits were exposed at the seabed by faulting, mass wasting, and erosion. Scanning electron microscopy and microprobe analyses indicate the presence of both amorphous and crystalline 10 ?? and 7 ?? manganate minerals, the fundamental chemical difference being high water contents in the amorphous Mn oxides. Alternation of amorphous and crystalline laminae occurs in many samples, which likely resulted from initial rapid precipitation of amorphous Mn oxides from waxing pulses of hydrothermal fluids followed by precipitation of slow forming crystallites during waning stages. The chemical composition is characteristic of a hydrothermal origin including strong fractionation between Fe (mean 0.9 wt %) and Mn (mean 48 wt %) for the stratabound Mn, generally low trace metal contents, and very low rare earth element and platinum group element contents. However, Mo, Cd, Zn, Cu, Ni, and Co occur in high concentrations in some samples and may be good indicator elements for proximity to the heat source or to massive sulfide deposits. For the Mn sandstones, Fe (mean-8.4%) and Mn (12.4%) are not significantly fractionated because of high Fe contents in the volcaniclastic material. However, the proportion of hydrothermal Fe (nondetrital Fe) to total Fe is remarkably constant (49-58%) for all the sample groups, regardless of the degree of

  12. Diffuse flow hydrothermal manganese mineralization along the active Mariana and southern Izu-Bonin arc system, western Pacific

    Science.gov (United States)

    Hein, James R.; Schulz, Marjorie S.; Dunham, Rachel E.; Stern, Robert J.; Bloomer, Sherman H.

    2008-08-01

    Abundant ferromanganese oxides were collected along 1200 km of the active Izu-Bonin-Mariana arc system. Chemical compositions and mineralogy show that samples were collected from two deposit types: Fe-Mn crusts of mixed hydrogenetic/hydrothermal origin and hydrothermal Mn oxide deposits; this paper addresses only the second type. Mn oxides cement volcaniclastic and biogenic sandstone and breccia layers (Mn sandstone) and form discrete dense stratabound layers along bedding planes and within beds (stratabound Mn). The Mn oxide was deposited within coarse-grained sediments from diffuse flow systems where precipitation occurred below the seafloor. Deposits were exposed at the seabed by faulting, mass wasting, and erosion. Scanning electron microscopy and microprobe analyses indicate the presence of both amorphous and crystalline 10 Å and 7 Å manganate minerals, the fundamental chemical difference being high water contents in the amorphous Mn oxides. Alternation of amorphous and crystalline laminae occurs in many samples, which likely resulted from initial rapid precipitation of amorphous Mn oxides from waxing pulses of hydrothermal fluids followed by precipitation of slow forming crystallites during waning stages. The chemical composition is characteristic of a hydrothermal origin including strong fractionation between Fe (mean 0.9 wt %) and Mn (mean 48 wt %) for the stratabound Mn, generally low trace metal contents, and very low rare earth element and platinum group element contents. However, Mo, Cd, Zn, Cu, Ni, and Co occur in high concentrations in some samples and may be good indicator elements for proximity to the heat source or to massive sulfide deposits. For the Mn sandstones, Fe (mean 8.4%) and Mn (12.4%) are not significantly fractionated because of high Fe contents in the volcaniclastic material. However, the proportion of hydrothermal Fe (nondetrital Fe) to total Fe is remarkably constant (49-58%) for all the sample groups, regardless of the degree of

  13. Reconstruction of Ancestral Hydrothermal Systems on Mount Rainier Using Hydrothermally Altered Rocks in Holocene Debris Flows and Tephras

    Science.gov (United States)

    John, D. A.; Breit, G. N.; Sisson, T. W.; Vallance, J. W.; Rye, R. O.

    2005-12-01

    geophysical data, as well as analog fossil hydrothermal systems in volcanoes elsewhere, constrain hydrothermal alteration geometry on the pre-Osceola-collapse edifice of Mount Rainier. Relatively narrow zones of acid magmatic-hydrothermal alteration in the central core of the volcano grade to more widely distributed smectite-pyrite alteration farther out on the upper flanks, capped by steam-heated alteration with a large component of alteration resulting from condensation of fumarolic vapor above the water table. Alteration was polygenetic in zones formed episodically, and was strongly controlled by fluxes of heat and magmatic fluid and by local permeability.

  14. Modeling free energy availability from Hadean hydrothermal systems to the first metabolism.

    Science.gov (United States)

    Simoncini, E; Russell, M J; Kleidon, A

    2011-12-01

    Off-axis Hydrothermal Systems (HSs) are seen as the possible setting for the emergence of life. As the availability of free energy is a general requirement to drive any form of metabolism, we ask here under which conditions free energy generation by geologic processes is greatest and relate these to the conditions found at off-axis HSs. To do so, we present a conceptual model in which we explicitly capture the energetics of fluid motion and its interaction with exothermic reactions to maintain a state of chemical disequilibrium. Central to the interaction is the temperature at which the exothermic reactions take place. This temperature not only sets the equilibrium constant of the chemical reactions and thereby the distance of the actual state to chemical equilibrium, but these reactions also shape the temperature gradient that drives convection and thereby the advection of reactants to the reaction sites and the removal of the products that relate to geochemical free energy generation. What this conceptual model shows is that the positive feedback between convection and the chemical kinetics that is found at HSs favors a greater rate of free energy generation than in the absence of convection. Because of the lower temperatures and because the temperature of reactions is determined more strongly by these dynamics rather than an external heat flux, the conditions found at off-axis HSs should result in the greatest rates of geochemical free energy generation. Hence, we hypothesize from these thermodynamic considerations that off-axis HSs seem most conducive for the emergence of protometabolic pathways as these provide the greatest, abiotic generation rates of chemical free energy.

  15. Development of a parameterization scheme of mesoscale convective systems

    International Nuclear Information System (INIS)

    Cotton, W.R.

    1994-01-01

    The goal of this research is to develop a parameterization scheme of mesoscale convective systems (MCS) including diabatic heating, moisture and momentum transports, cloud formation, and precipitation. The approach is to: Perform explicit cloud-resolving simulation of MCSs; Perform statistical analyses of simulated MCSs to assist in fabricating a parameterization, calibrating coefficients, etc.; Test the parameterization scheme against independent field data measurements and in numerical weather prediction (NWP) models emulating general circulation model (GCM) grid resolution. Thus far we have formulated, calibrated, implemented and tested a deep convective engine against explicit Florida sea breeze convection and in coarse-grid regional simulations of mid-latitude and tropical MCSs. Several explicit simulations of MCSs have been completed, and several other are in progress. Analysis code is being written and run on the explicitly simulated data

  16. Products of an Artificially Induced Hydrothermal System at Yucca Mountain

    International Nuclear Information System (INIS)

    Levy, S.

    2000-01-01

    Studies of mineral deposition in the recent geologic past at Yucca Mountain, Nevada, address competing hypotheses of hydrothermal alteration and deposition from percolating groundwater. The secondary minerals being studied are calcite-opal deposits in fractures and lithophysal cavities of ash-flow tuffs exposed in the Exploratory Studies Facility (ESF), a 7.7-km tunnel excavated by the Yucca Mountain Site Characterization Project within Yucca Mountain. An underground field test in the ESF provided information about the minerals deposited by a short-lived artificial hydrothermal system and an opportunity for comparison of test products with the natural secondary minerals. The heating phase lasted nine months, followed by a nine-month cooling period. Natural pore fluids were the only source of water during the thermal test. Condensation and reflux of water driven away from the heater produced fluid flow in certain fractures and intersecting boreholes. The mineralogic products of the thermal test are calcite-gypsum aggregates of less than 4-micrometer crystals and amorphous silica as glassy scale less than 0.2 mm thick and as mounds of tubules with diameters less than 0.7 micrometers. The minute crystal sizes of calcite and gypsum from the field test are very different from the predominantly coarser calcite crystals (up to cm scale) in natural secondary-mineral deposits at the site. The complex micrometer-scale textures of the amorphous silica differ from the simple forms of opal spherules and coatings in the natural deposits, even though some natural spherules are as small as 1 micrometer. These differences suggest that the natural minerals, especially if they were of hydrothermal origin, may have developed coarser or simpler forms during subsequent episodes of dissolution and redeposition. The presence of gypsum among the test products and its absence from the natural secondary-mineral assemblage may indicate a higher degree of evaporation during the test than

  17. The 2006 Eruption of Raoul Volcano (Kermadecs): A Phreato-magmatic Event From a Hydrothermally-Sealed Volcanic Conduit System.

    Science.gov (United States)

    Christenson, B. W.; Reyes, A. G.; Werner, C. A.

    2006-12-01

    The March 17, 2006 eruption from Raoul volcano (Kermadec Islands, NZ), which tragically claimed the life of NZ Department of Conservation staff member Mark Kearney, is being interpreted as a magmatic-hydrothermal event triggered by shaking associated with regional earthquake swarm activity. Although the eruption released ca. 200 T of SO2, thus confirming its magmatic nature, it occurred without significant precursory volcanic seismicity, and without any of the precursory responses of the volcanic hydrothermal system which were observed prior to the last eruption in 1964. Raoul Island has a long and varied eruption history dating back > 1.4 ma, and has been hydrothermally active throughout historic time. Present day fumarolic and hotspring discharges within Raoul caldera point to the existence of a small but well established, mixed meteoric - seawater hydrothermal system within the volcano. Magmatic signatures are apparent in fumarolic gas discharges, but are heavily masked by their interaction with hydrothermal system fluids (eg. near complete scrubbing of sulphur and halogen gases from the boiling point fumarolic discharges). A diffuse degassing study conducted in 2004 revealed that ca. 80 T/d CO2 is passively discharged from the volcano, suggesting that ongoing (albeit low level) convective degassing of magma occurs at depth. Interestingly, vent locations from the 2006 eruption correspond to areas of relatively low CO2 discharge on the crater floor in 2004. This, in conjunction with the preliminary findings of abundant hydrothermal mineralisation (calcite, anhydrite, quartz) in eruption ejecta, suggests that the main volcanic conduits had become effectively sealed during the interval since the last eruption. Calcite-hosted fluid inclusions are CO2 clathrate-bearing, and have relatively low homogenisation temperatures (165-180 °C), suggesting that the seal environment was both gas-charged and shallowly seated (< 200 m). Shaking associated with the regional

  18. Wavelet Scale Analysis of Mesoscale Convective Systems for Detecting Deep Convection From Infrared Imagery

    Science.gov (United States)

    Klein, Cornelia; Belušić, Danijel; Taylor, Christopher M.

    2018-03-01

    Mesoscale convective systems (MCSs) are frequently associated with rainfall extremes and are expected to further intensify under global warming. However, despite the significant impact of such extreme events, the dominant processes favoring their occurrence are still under debate. Meteosat geostationary satellites provide unique long-term subhourly records of cloud top temperatures, allowing to track changes in MCS structures that could be linked to rainfall intensification. Focusing on West Africa, we show that Meteosat cloud top temperatures are a useful proxy for rainfall intensities, as derived from snapshots from the Tropical Rainfall Measuring Mission 2A25 product: MCSs larger than 15,000 km2 at a temperature threshold of -40°C are found to produce 91% of all extreme rainfall occurrences in the study region, with 80% of the storms producing extreme rain when their minimum temperature drops below -80°C. Furthermore, we present a new method based on 2-D continuous wavelet transform to explore the relationship between cloud top temperature and rainfall intensity for subcloud features at different length scales. The method shows great potential for separating convective and stratiform cloud parts when combining information on temperature and scale, improving the common approach of using a temperature threshold only. We find that below -80°C, every fifth pixel is associated with deep convection. This frequency is doubled when looking at subcloud features smaller than 35 km. Scale analysis of subcloud features can thus help to better exploit cloud top temperature data sets, which provide much more spatiotemporal detail of MCS characteristics than available rainfall data sets alone.

  19. Microbial Geochemistry in Shallow-Sea Hydrothermal Systems

    Science.gov (United States)

    Amend, J. P.; Pichler, T.

    2006-12-01

    Shallow-sea hydrothermal systems are far more ubiquitous than generally recognized. Approximately 50-60 systems are currently known, occurring world-wide in areas of high heat flow, such as, volcanic island arcs, near-surface mid-ocean ridges, and intraplate oceanic volcanoes. In contrast to deep-sea systems, shallow- sea vent fluids generally include a meteoric component, they experience phase separation near the sediment- water interface, and they discharge into the photic zone (thermophilic bacteria and archaea. Perhaps because deep-sea smokers and continental hot springs are visually more stunning, shallow-sea systems are often overlooked study sites. We will discuss their particular features that afford unique opportunities in microbial geochemistry. Two of the better studied examples are at Vulcano Island (Italy) and Ambitle Island (Papua New Guinea). The vents and sediment seeps at Vulcano are the "type locality" for numerous cultured hyperthermophiles, including the bacteria Aquifex and Thermotoga, the crenarchaeon Pyrodictium, and the Euryarchaeota Archaeoglobus and Pyrococcus. Isotope-labeled incubation experiments of heated sediments and an array of culturing studies have shown that simple organic compounds are predominantly fermented or anaerobically respired with sulfate. 16S rRNA gene surveys, together with fluorescent in situ hybridization studies, demonstrated the dominance of key thermophilic bacteria and archaea (e.g., Aquificales, Thermotogales, Thermococcales, Archaeoglobales) in the sediments and the presence of a broad spectrum of mostly uncultured crenarchaeota in several vent waters, sediment samples, and geothermal wells. Thermodynamic modeling quantified potential energy yields from aerobic and anaerobic respiration reactions and fermentation reactions. In contrast to their deep-sea counterparts, shallow-sea hydrothermal systems are often characterized by high arsenic concentrations of more than 500-times seawater levels. The arsenic

  20. Mobile Disdrometer Observations of Nocturnal Mesoscale Convective Systems During PECAN

    Science.gov (United States)

    Bodine, D. J.; Rasmussen, K. L.

    2015-12-01

    Understanding microphysical processes in nocturnal mesoscale convective systems (MCSs) is an important objective of the Plains Elevated Convection At Night (PECAN) experiment, which occurred from 1 June - 15 July 2015 in the central Great Plains region of the United States. Observations of MCSs were collected using a large array of mobile and fixed instrumentation, including ground-based radars, soundings, PECAN Integrated Sounding Arrays (PISAs), and aircraft. In addition to these observations, three mobile Parsivel disdrometers were deployed to obtain drop-size distribution (DSD) measurements to further explore microphysical processes in convective and stratiform regions of nocturnal MCSs. Disdrometers were deployed within close range of a multiple frequency network of mobile and fixed dual-polarization radars (5 - 30 km range), and near mobile sounding units and PISAs. Using mobile disdrometer and multiple-wavelength, dual-polarization radar data, microphysical properties of convective and stratiform regions of MCSs are investigated. The analysis will also examine coordinated Range-Height Indicator (RHI) scans over the disdrometers to elucidate vertical DSD structure. Analysis of dense observations obtained during PECAN in combination with mobile disdrometer DSD measurements contributes to a greater understanding of the structural characteristics and evolution of nocturnal MCSs.

  1. Heat flux from magmatic hydrothermal systems related to availability of fluid recharge

    Science.gov (United States)

    Harvey, M. C.; Rowland, J.V.; Chiodini, G.; Rissmann, C.F.; Bloomberg, S.; Hernandez, P.A.; Mazot, A.; Viveiros, F.; Werner, Cynthia A.

    2015-01-01

    Magmatic hydrothermal systems are of increasing interest as a renewable energy source. Surface heat flux indicates system resource potential, and can be inferred from soil CO2 flux measurements and fumarole gas chemistry. Here we compile and reanalyze results from previous CO2 flux surveys worldwide to compare heat flux from a variety of magma-hydrothermal areas. We infer that availability of water to recharge magmatic hydrothermal systems is correlated with heat flux. Recharge availability is in turn governed by permeability, structure, lithology, rainfall, topography, and perhaps unsurprisingly, proximity to a large supply of water such as the ocean. The relationship between recharge and heat flux interpreted by this study is consistent with recent numerical modeling that relates hydrothermal system heat output to rainfall catchment area. This result highlights the importance of recharge as a consideration when evaluating hydrothermal systems for electricity generation, and the utility of CO2 flux as a resource evaluation tool.

  2. Mo isotope fractionation during hydrothermal evolution of porphyry Cu systems

    Science.gov (United States)

    Shafiei, Behnam; Shamanian, GholamHossein; Mathur, Ryan; Mirnejad, Hassan

    2015-03-01

    We present Mo isotope compositions of molybdenite types from three successive stages of ore deposition in several porphyry copper deposits of the Kerman region, Iran. The data provide new insights into controlling processes on Mo isotope fractionation during the hydrothermal evolution of porphyry systems. The Mo isotope compositions of 27 molybdenite samples show wide variations in δ97Mo ranging from -0.37 to +0.92 ‰. The data reveal that molybdenites in the early and transitional stages of mineralization (preferentially 2H polytypes; δ97Mo mean = 0.35 ‰) have higher δ97Mo values than late stage (mainly 3R polytypes; δ97Mo mean = 0.02 ‰) molybdenites. This trend suggests that fractionation of Mo isotopes occurred in high-temperature stages of mineralization and that hydrothermal systems generally evolve towards precipitation of molybdenite with lower δ97Mo values. Taking into account the genetic models proposed for porphyry Cu deposits along with the temperature-dependent fractionation of Mo isotope ratios, it is proposed that large variations of Mo isotopes in the early and the transitional stages of ore deposition could be controlled by the separation of the immiscible ore-forming fluid phases with different density, pH, and ƒO2 properties (i.e., brine and vapor). The fractionation of Mo isotopes during fluid boiling and Rayleigh distillation processes likely dominates the Mo isotope budget of the remaining ore-forming fluids for the late stage of mineralization. The lower δ97Mo values in the late stage of mineralization can be explained by depletion of the late ore-forming hydrothermal solutions in 97Mo, as these fluids have moved to considerable distance from the source. Finally, the relationship observed between MoS2 polytypes (2H and 3R) and their Mo isotopic compositions can be explained by the molecular vibration theory, in which heavier isotopes are preferentially partitioned into denser primary 2H MoS2 crystals.

  3. A Generalized Evolution Criterion in Nonequilibrium Convective Systems

    Science.gov (United States)

    Ichiyanagi, Masakazu; Nisizima, Kunisuke

    1989-04-01

    A general evolution criterion, applicable to transport processes such as the conduction of heat and mass diffusion, is obtained as a direct version of the Le Chatelier-Braun principle for stationary states. The present theory is not based on any radical departure from the conventional one. The generalized theory is made determinate by proposing the balance equations for extensive thermodynamic variables which will reflect the character of convective systems under the assumption of local equilibrium. As a consequence of the introduction of source terms in the balance equations, there appear additional terms in the expression of the local entropy production, which are bilinear in terms of the intensive variables and the sources. In the present paper, we show that we can construct a dissipation function for such general cases, in which the premises of the Glansdorff-Prigogine theory are accumulated. The new dissipation function permits us to formulate a generalized evolution criterion for convective systems.

  4. Dry storage systems with free convection air cooling

    International Nuclear Information System (INIS)

    Kioes, S.R.

    1980-01-01

    Several design principles to remove heat from the spent fuel by free air convection are illustrated and described. The key safety considerations were felt to be: loss of coolant is impossible as the passive system uses air as a coolant; overheating is precluded because as the temperatures of the containers rises the coolant flow rate increases; mass of the storage building provides a large heat sink and therefore a rapid temperature rise is impossible; and lack of any active external support requirements makes the cooling process less likely to equipment or operator failures. An example of this type of storage already exists. The German HTGR is operated with spherical graphite fuel elements which are stored in canister and in storage cells. The concept is a double cooling system with free convection inside the cells and heat exchange via two side walls of the cell to the ambient air in the cooling ducts. Technical description of the TN 1300 cask is also presented

  5. Lightning characteristics of derecho producing mesoscale convective systems

    Science.gov (United States)

    Bentley, Mace L.; Franks, John R.; Suranovic, Katelyn R.; Barbachem, Brent; Cannon, Declan; Cooper, Stonie R.

    2016-06-01

    Derechos, or widespread, convectively induced wind storms, are a common warm season phenomenon in the Central and Eastern United States. These damaging and severe weather events are known to sweep quickly across large spatial regions of more than 400 km and produce wind speeds exceeding 121 km h-1. Although extensive research concerning derechos and their parent mesoscale convective systems already exists, there have been few investigations of the spatial and temporal distribution of associated cloud-to-ground lightning with these events. This study analyzes twenty warm season (May through August) derecho events between 2003 and 2013 in an effort to discern their lightning characteristics. Data used in the study included cloud-to-ground flash data derived from the National Lightning Detection Network, WSR-88D imagery from the University Corporation for Atmospheric Research, and damaging wind report data obtained from the Storm Prediction Center. A spatial and temporal analysis was conducted by incorporating these data into a geographic information system to determine the distribution and lightning characteristics of the environments of derecho producing mesoscale convective systems. Primary foci of this research include: (1) finding the approximate size of the lightning activity region for individual and combined event(s); (2) determining the intensity of each event by examining the density and polarity of lightning flashes; (3) locating areas of highest lightning flash density; and (4) to provide a lightning spatial analysis that outlines the temporal and spatial distribution of flash activity for particularly strong derecho producing thunderstorm episodes.

  6. The importance of shallow hydrothermal island arc systems in ocean biogeochemistry

    NARCIS (Netherlands)

    Hawkes, J.A.; Connelly, D.P.; Rijkenberg, M.J.A.; Achterberg, E.P.

    2014-01-01

    Hydrothermal venting often occurs at submarine volcanic calderas on island arc chains, typically at shallower depths than mid-ocean ridges. The effect of these systems on ocean biogeochemistry has been under-investigated to date. Here we show that hydrothermal effluent from an island arc caldera was

  7. Application of Hydrothermal and Non-Hydrothermal TiO2 Nanoporous Materials as New Adsorbents for Removal of Heavy Metal Ions from Aqueous System

    Directory of Open Access Journals (Sweden)

    Mansoor Anbia

    2016-06-01

    Full Text Available Hydrothermal and non-hydrothermal spherical TiO2 nanoporous with crystalline framework were prepared by sol-gel method. The Crystalline structures, morphologies and surface texturing of materials were determined by X-ray diffraction (XRD, scanning electron microscopy (SEM and N2 adsorption-desorption isotherms. The Hydrothermal spherical TiO2 nanoporous was found to have a narrow and strong pore size distribution peaks with average of 37.8 Å and pore volume of 0.41 cm3/g and the (Brunauer–Emmett–TellerBET specific surface area of 365 m2/g. Hydrothermal and non-hydrothermal spherical TiO2 nanoporous have been used as adsorbent to study of the adsorption behavior of Pb(II, Co(II and Ni(II ions from aqueous system in a batch system. Effect of equilibrium time on adsorption Pb(II, Co(II and Ni(II ions on these adsorbent was studied The results show that the shaking time 0.5 to 10h has no serious effect on the percentage of ions removal, and the adsorption is fast in all cases. The maximum uptake capacities of Hydrothermal and non-hydrothermal spherical TiO2 nanoporous was calculated. Both hydrothermal and non-hydrothermal TiO2 nanoporous materials were found to have very good potential as new adsorbents in removal of these ions. In batch systems the maximum uptake capacities of Pb(II, Ni(II and Co(II on the hydrothermal and non-hydrothermal TiO2 nanoporous materials was Co(II > Pb(II > Ni(II and Co(II > Ni(II > Pb(II, respectively.

  8. Comparison of microbial communities associated with three Atlantic ultramafic hydrothermal systems.

    Science.gov (United States)

    Roussel, Erwan G; Konn, Cécile; Charlou, Jean-Luc; Donval, Jean-Pierre; Fouquet, Yves; Querellou, Joël; Prieur, Daniel; Bonavita, Marie-Anne Cambon

    2011-09-01

    The distribution of Archaea and methanogenic, methanotrophic and sulfate-reducing communities in three Atlantic ultramafic-hosted hydrothermal systems (Rainbow, Ashadze, Lost City) was compared using 16S rRNA gene and functional gene (mcrA, pmoA and dsrA) clone libraries. The overall archaeal community was diverse and heterogeneously distributed between the hydrothermal sites and the types of samples analyzed (seawater, hydrothermal fluid, chimney and sediment). The Lost City hydrothermal field, characterized by high alkaline warm fluids (pH>11; Tphylum and Methanopyrales order were also retrieved from the Rainbow and Ashadze hydrothermal fluids. However, the methanogenic Methanococcales was the most widely distributed hyper/thermophilic archaeal group among the hot and acidic ultramafic-hosted hydrothermal system environments. Most of the lineages detected are linked to methane and hydrogen cycling, suggesting that in ultramafic-hosted hydrothermal systems, large methanogenic and methanotrophic communities could be fuelled by hydrothermal fluids highly enriched in methane and hydrogen. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  9. Tropical continental downdraft characteristics: mesoscale systems versus unorganized convection

    Science.gov (United States)

    Schiro, Kathleen A.; Neelin, J. David

    2018-02-01

    Downdrafts and cold pool characteristics for strong mesoscale convective systems (MCSs) and isolated, unorganized deep precipitating convection are analyzed using multi-instrument data from the DOE Atmospheric Radiation Measurement (ARM) GoAmazon2014/5 campaign. Increases in column water vapor (CWV) are observed leading convection, with higher CWV preceding MCSs than for isolated cells. For both MCSs and isolated cells, increases in wind speed, decreases in surface moisture and temperature, and increases in relative humidity occur coincidentally with system passages. Composites of vertical velocity data and radar reflectivity from a radar wind profiler show that the downdrafts associated with the sharpest decreases in surface equivalent potential temperature (θe) have a probability of occurrence that increases with decreasing height below the freezing level. Both MCSs and unorganized convection show similar mean downdraft magnitudes and probabilities with height. Mixing computations suggest that, on average, air originating at heights greater than 3 km must undergo substantial mixing, particularly in the case of isolated cells, to match the observed cold pool θe, implying a low typical origin level. Precipitation conditionally averaged on decreases in surface equivalent potential temperature (Δθe) exhibits a strong relationship because the most negative Δθe values are associated with a high probability of precipitation. The more physically motivated conditional average of Δθe on precipitation shows that decreases in θe level off with increasing precipitation rate, bounded by the maximum difference between surface θe and its minimum in the profile aloft. Robustness of these statistics observed across scales and regions suggests their potential use as model diagnostic tools for the improvement of downdraft parameterizations in climate models.

  10. Magnetospheric convection and current system in the dayside polar cap

    International Nuclear Information System (INIS)

    Nishida, A.; Mukai, T.; Tsuruda, K.; Hayakawa, H.

    1992-01-01

    Field and particle observations on EXOS-D (Akebono) have yielded new information on convection and current system in the dayside polar cap. Convection patterns are distinctly different depending upon whether IMF B z is northward or southward. The number of convection cells is two when B z is southward but four when B z is northward. Lobe cells in which plasma flows sunward in the region of open field lines are observed as a pair (of which one is in the dawn and the other in the dusk sector) for any polarity of IMF B y and B z . Ions in the keV range precipitate not only in the dayside cusp region but also along the sunward directed streamlines of the dawn and dusk lobe cells. These observations require reconsideration on the position and the extent of the reconnection region on the magnetopause. They also suggest that the magnetotail plays a vital role in some phenomena which have been ascribed to dayside magnetopause processes. We have not been able to find evidence to prove the presence of the viscous cell under southward IMF

  11. Origin of Abiotic Methane in Submarine Hydrothermal Systems

    Science.gov (United States)

    Seewald, J. S.; German, C. R.; Grozeva, N. G.; Klein, F.; McDermott, J. M.; Ono, S.; Reeves, E. P.; Wang, D. T.

    2018-05-01

    Results of recent investigations into the chemical and isotopic composition of actively venting submarine hydrothermal fluids and volatile species trapped in fluid inclusions will be discussed in the context of processes responsible for abiotic CH4 formation.

  12. Geothermal Frontier: Penetrate a boundary between hydrothermal convection and heat conduction zones to create 'Beyond Brittle Geothermal Reservoir'

    Science.gov (United States)

    Tsuchiya, N.; Asanuma, H.; Sakaguchi, K.; Okamoto, A.; Hirano, N.; Watanabe, N.; Kizaki, A.

    2013-12-01

    EGS has been highlightened as a most promising method of geothermal development recently because of applicability to sites which have been considered to be unsuitable for geothermal development. Meanwhile, some critical problems have been experimentally identified, such as low recovery of injected water, difficulties to establish universal design/development methodology, and occurrence of large induced seismicity. Future geothermal target is supercritical and superheated geothermal fluids in and around ductile rock bodies under high temperatures. Ductile regime which is estimated beyond brittle zone is target region for future geothermal development due to high enthalpy fluids and relatively weak water-rock interaction. It is very difficult to determine exact depth of Brittle-Ductile boundary due to strong dependence of temperature (geotherm) and strain rate, however, ductile zone is considered to be developed above 400C and below 3 km in geothermal fields in Tohoku District. Hydrothermal experiments associated with additional advanced technology will be conducting to understand ';Beyond brittle World' and to develop deeper and hotter geothermal reservoir. We propose a new concept of the engineered geothermal development where reservoirs are created in ductile basement, expecting the following advantages: (a)simpler design and control the reservoir, (b)nearly full recovery of injected water, (c)sustainable production, (d)cost reduction by development of relatively shallower ductile zone in compression tectonic zones, (e)large quantity of energy extraction from widely distributed ductile zones, (f)establishment of universal and conceptual design/development methodology, and (g) suppression of felt earthquakes from/around the reservoirs. In ductile regime, Mesh-like fracture cloud has great potential for heat extraction between injection and production wells in spite of single and simple mega-fracture. Based on field observation and high performance hydrothermal

  13. Vein networks in hydrothermal systems provide constraints for the monitoring of active volcanoes.

    Science.gov (United States)

    Cucci, Luigi; Di Luccio, Francesca; Esposito, Alessandra; Ventura, Guido

    2017-03-10

    Vein networks affect the hydrothermal systems of many volcanoes, and variations in their arrangement may precede hydrothermal and volcanic eruptions. However, the long-term evolution of vein networks is often unknown because data are lacking. We analyze two gypsum-filled vein networks affecting the hydrothermal field of the active Lipari volcanic Island (Italy) to reconstruct the dynamics of the hydrothermal processes. The older network (E1) consists of sub-vertical, N-S striking veins; the younger network (E2) consists of veins without a preferred strike and dip. E2 veins have larger aperture/length, fracture density, dilatancy, and finite extension than E1. The fluid overpressure of E2 is larger than that of E1 veins, whereas the hydraulic conductance is lower. The larger number of fracture intersections in E2 slows down the fluid movement, and favors fluid interference effects and pressurization. Depths of the E1 and E2 hydrothermal sources are 0.8 km and 4.6 km, respectively. The decrease in the fluid flux, depth of the hydrothermal source, and the pressurization increase in E2 are likely associated to a magma reservoir. The decrease of fluid discharge in hydrothermal fields may reflect pressurization at depth potentially preceding hydrothermal explosions. This has significant implications for the long-term monitoring strategy of volcanoes.

  14. Carbon dioxide in magmas and implications for hydrothermal systems

    Science.gov (United States)

    Lowenstern, J. B.

    2001-01-01

    This review focuses on the solubility, origin, abundance, and degassing of carbon dioxide (CO2) in magma-hydrothermal systems, with applications for those workers interested in intrusion-related deposits of gold and other metals. The solubility of CO2 increases with pressure and magma alkalinity. Its solubility is low relative to that of H2O, so that fluids exsolved deep in the crust tend to have high CO2/H2O compared with fluids evolved closer to the surface. Similarly, CO2/H2O will typically decrease during progressive decompression- or crystallization-induced degassing. The temperature dependence of solubility is a function of the speciation of CO2, which dissolves in molecular form in rhyolites (retrograde temperature solubility), but exists as dissolved carbonate groups in basalts (prograde). Magnesite and dolomite are stable under a relatively wide range of mantle conditions, but melt just above the solidus, thereby contributing CO2 to mantle magmas. Graphite, diamond, and a free CO2-bearing fluid may be the primary carbon-bearing phases in other mantle source regions. Growing evidence suggests that most CO2 is contributed to arc magmas via recycling of subducted oceanic crust and its overlying sediment blanket. Additional carbon can be added to magmas during magma-wallrock interactions in the crust. Studies of fluid and melt inclusions from intrusive and extrusive igneous rocks yield ample evidence that many magmas are vapor saturated as deep as the mid crust (10-15 km) and that CO2 is an appreciable part of the exsolved vapor. Such is the case in both basaltic and some silicic magmas. Under most conditions, the presence of a CO2-bearing vapor does not hinder, and in fact may promote, the ascent and eruption of the host magma. Carbonic fluids are poorly miscible with aqueous fluids, particularly at high temperature and low pressure, so that the presence of CO2 can induce immiscibility both within the magmatic volatile phase and in hydrothermal systems

  15. Convective Performance of Nanofluids in Commercial Electronics Cooling Systems

    International Nuclear Information System (INIS)

    Roberts, N.A.; Walker, D.G.

    2010-01-01

    Nanofluids are stable engineered colloidal suspensions of a small fraction of nanoparticles in a base fluid. Nanofluids have shown great promise as heat transfer fluids over typically used base fluids and fluids with micron sized particles. Suspensions with micron sized particles are known to settle rapidly and cause clogging and damage to the surfaces of pumping and flow equipment. These problems are dramatically reduced in nanofluids. In the current work we investigate the performance of different volume loadings of water-based alumina nanofluids in a commercially available electronics cooling system. The commercially available system is a water block used for liquid cooling of a computational processing unit. The size of the nanoparticles in the study is 20-30 nm. Results show an enhancement in convective heat transfer due to the addition of nanoparticles in the commercial cooling system with volume loadings of nanoparticles up to 1.5% by volume. The enhancement in the convective performance observed is similar to what has been reported in well controlled and understood systems and is commensurate with bulk models. The current nanoparticle suspensions showed visible signs of settling which varied from hours to weeks depending on the size of the particles used.

  16. Impairment of Heat Transfer in the Passive Cooling System due to Mixed Convection

    Energy Technology Data Exchange (ETDEWEB)

    Chae Myeong Seon; Chung, Bum Jin [Kyunghee University, Yongin (Korea, Republic of); Kim, Jong Hwan [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    In the passive cooling devices, the buoyant flows are induced. However the local Nusselt number of natural convective flow can be partly impaired due to the development of the mixed convective flows. This paper discusses impairment of heat transfer in the passive cooling system in relation to the development of mixed convection. The present work describes the preliminary plan to explore the phenomena experimentally. This paper is to discuss and make the plan to experiment the impairment of heat transfer in the passive cooling system due to mixed convection. In the sufficiently high passive cooling devices, the natural convection flow behavior can be mixed convection. The local Nusselt number distribution exhibits the non-monotonic behavior as axial position, since the buoyancy-aided with mixed convection was appeared. This is the part of the experimental work.

  17. Energy landscapes shape microbial communities in hydrothermal systems on the Arctic Mid-Ocean Ridge

    OpenAIRE

    Dahle, H?kon; ?kland, Ingeborg; Thorseth, Ingunn H; Pederesen, Rolf B; Steen, Ida H

    2015-01-01

    Methods developed in geochemical modelling combined with recent advances in molecular microbial ecology provide new opportunities to explore how microbial communities are shaped by their chemical surroundings. Here, we present a framework for analyses of how chemical energy availability shape chemotrophic microbial communities in hydrothermal systems through an investigation of two geochemically different basalt-hosted hydrothermal systems on the Arctic Mid-Ocean Ridge: the Soria Moria Vent f...

  18. Metallogenic hydrothermal solution system of post volcanic magma in Xiangshan ore field

    International Nuclear Information System (INIS)

    Xu Hengli; Shao Fei; Zou Maoqin

    2009-01-01

    This paper has systematically described uranium metallogenic characteristics of Xiangshan ore field.Sources of metallogenic materials are discussed in different temporal and spatial scale. Combining with background analysis of metallogenic tectonic-magmatic-geodynamics, formation and evolution of metallogenic hydrothermal solution system in Xiangshan volcanic basin are studied. Metallogenic hydrothermal solution system in Xiangshan ore field is considered as the objective product of systematic evolution of hydrothermal solution in post volcanic magma constrained by regional tectonic environment. In time scale, metallogenic hydrothermal solution system developed for about 50 Ma, but its active spaces varied in different time domains. So temporal and spatial distribution of uranium mineralization is constrained. Further exploration for the ore field is also suggested in this paper. (authors)

  19. Resistivity structure and geochemistry of the Jigokudani Valley hydrothermal system, Mt. Tateyama, Japan

    Science.gov (United States)

    Seki, Kaori; Kanda, Wataru; Tanbo, Toshiya; Ohba, Takeshi; Ogawa, Yasuo; Takakura, Shinichi; Nogami, Kenji; Ushioda, Masashi; Suzuki, Atsushi; Saito, Zenshiro; Matsunaga, Yasuo

    2016-10-01

    This study clarifies the hydrothermal system of Jigokudani Valley near Mt. Tateyama volcano in Japan by using a combination of audio-frequency magnetotelluric (AMT) survey and hot-spring water analysis in order to assess the potential of future phreatic eruptions in the area. Repeated phreatic eruptions in the area about 40,000 years ago produced the current valley morphology, which is now an active solfatara field dotted with hot springs and fumaroles indicative of a well-developed hydrothermal system. The three-dimensional (3D) resistivity structure of the hydrothermal system was modeled by using the results of an AMT survey conducted at 25 locations across the valley in 2013-2014. The model suggests the presence of a near-surface highly conductive layer of falling largely on a mixing line between magmatic fluids and local meteoric water (LMW). The geochemical analysis suggests that the hydrothermal system includes a two-phase zone of vapor-liquid. A comparison of the resistivity structure and the geochemically inferred structure suggests that a hydrothermal reservoir is present at a depth of approximately 500 m, from which hot-spring water differentiates into the three observed types. The two-phase zone appears to be located immediately beneath the cap rock structure. These findings suggest that the hydrothermal system of Jigokudani Valley exhibits a number of factors that could trigger a future phreatic eruption.

  20. Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

    Science.gov (United States)

    Zhang, Yao; Zhao, Zihao; Chen, Chen-Tung Arthur; Tang, Kai; Su, Jianqiang; Jiao, Nianzhi

    2012-01-01

    To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4)) concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4) was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH(4) concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan.

  1. Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

    Directory of Open Access Journals (Sweden)

    Yao Zhang

    Full Text Available To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4 concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4 was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH(4 concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan.

  2. Rare earth mobility in hydrothermal ore-forming systems

    International Nuclear Information System (INIS)

    Cornell, D.H.; Schade, J.; Scheepers, R.; Watkeys, M.K.

    1988-01-01

    Rocks and ores which form by magmatic processes display a range of chondrite-normalised rare earth profiles. One REE (rare earth elements) profile feature which seems unrelated to magmatic processes is the birdwing profile, in which both heavy and light rare earths are enriched relative to the middle rare earths. Birdwing rare earth profiles are an easily identified geochemical anomaly. It is proposed that rare earth geochemistry could be applied in geochemical prospecting for ore formed by hydrothermal processes. 5 figs

  3. Shallow magmatic degassing into the hydrothermal system of Copahue, Argentina

    Science.gov (United States)

    Varekamp, J.; Ouimette, A.; Kreulen, R.; Delpino, D.; Bermudez, A.

    2001-05-01

    Copahue volcano has a crater lake and acid hot springs that discharge into the Rio Agrio river system. These fluids are very concentrated (up to 6 percent sulfate), rich in rock-forming elements (up to 2000 ppm Mg) and small spheres of native sulfur float in the crater lake. The stable isotope composition of the waters (delta 18O =-2.1 to + 3.6 per mille; delta D = -49 to -26 per mille) indicates that the hot spring waters are at their most concentrated about 70 percent volcanic brine and 30 percent glacial meltwater. The crater lake waters have similar mixing proportions but added isotope effects from intense evaporation. Further dilution of the waters in the Rio Agrio gives values closer to local meteoric waters (delta 18O = -11 per mille; delta D = -77 per mille), whereas evaporation in closed ponds led to very heavy water (up to delta 18O = +12 per mille). The delta 34S value of dissolved sulfate is +14.2 per mille, whereas the native sulfur has values of -8.2 to -10.5 per mille. The heavy sulfate probably formed when SO2 disproportionated into bisulfate and native sulfur. We measured the sulfate fluxes in the Rio Agrio, and from these flux values and the stoichiometry of the disproportionation reaction we calculated the rate of liquid sulfur storage inside the volcano (6000 m3/year). During the eruptions of 1995/2000, large amounts of that stored liquid sulfur were ejected as pyroclastic sulfur. The calculated rate of rock dissolution (from rock- forming element fluxes in the Rio Agrio) suggests that the void space generated by rock dissolution is largely filled by native sulfur. The isotopic signature of the magmatic sulfur can be reconstituted at about +7 per mille, which is a source signature with superposed effects of shallow degassing. Lead isotope and 129Iodine data from the fluids indicate that subducted components may have played a role in the Copahue magma formation. Primary glass inclusions in plagioclase and olivine have 1110-1670 ppm Cl, 90-400 ppm

  4. Environments of Long-Lived Mesoscale Convective Systems Over the Central United States in Convection Permitting Climate Simulations: Long-Lived Mesoscale Convective Systems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qing [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Houze, Robert A. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Department of Atmospheric Sciences, University of Washington, Seattle WA USA; Leung, L. Ruby [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Feng, Zhe [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA

    2017-12-27

    Continental-scale convection-permitting simulations of the warm seasons of 2011 and 2012 reproduce realistic structure and frequency distribution of lifetime and event mean precipitation of mesoscale convective systems (MCSs) over the central United States. Analysis is performed to determine the environmental conditions conducive to generating the longest-lived MCSs and their subsequent interactions. The simulations show that MCSs systematically form over the Great Plains ahead of a trough in the westerlies in combination with an enhanced low-level jet from the Gulf of Mexico. These environmental properties at the time of storm initiation are most prominent for the MCSs that persist for the longest times. Systems reaching 9 h or more in lifetime exhibit feedback to the environment conditions through diabatic heating in the MCS stratiform regions. As a result, the parent synoptic-scale wave is strengthened as a divergent perturbation develops over the MCS at high levels, while a cyclonic circulation perturbation develops in the midlevels of the trough, where the vertical gradient of heating in the MCS region is maximized. The quasi-balanced mesoscale vortex helps to maintain the MCS over a long period of time by feeding dry, cool air into the environment at the rear of the MCS region, so that the MCS can draw in air that increases the evaporative cooling that helps maintain the MCS. At lower levels the south-southeasterly jet of warm moist air from the Gulf is enhanced in the presence of the synoptic-scale wave. That moisture supply is essential to the continued redevelopment of the MCS.

  5. VHF/UHF radar observations of tropical mesoscale convective systems over southern India

    Directory of Open Access Journals (Sweden)

    K. Kishore Kumar

    2005-07-01

    Full Text Available Several campaigns have been carried out to study the convective systems over Gadanki (13.5° N, 79.2° E, a tropical station in India, using VHF and UHF radars. The height-time sections of several convective systems are investigated in detail to study reflectivity, turbulence and vertical velocity structure. Structure and dynamics of the convective systems are the main objectives of these campaigns. The observed systems are classified into single- and multi-cell systems. It has been observed that most of the convective systems at this latitude are multi-cellular in nature. Simultaneous VHF and UHF radar observations are used to classify the observed precipitating systems as convective, intermediary and stratiform regions. Composite height profiles of vertical velocities in these regions were obtained and the same were compared with the profiles obtained at other geographical locations. These composite profiles of vertical velocity in the convective regions have shown their peaks in the mid troposphere, indicating that the maximum latent heat is being released at those heights. These profiles are very important for numerical simulations of the convective systems, which vary significantly from one geographical location to the other.

    Keywords. Meteorology and atmospheric dynamics (Mesoscale meteorology; Convective processes – Radio science (Remote sensing

  6. VHF/UHF radar observations of tropical mesoscale convective systems over southern India

    Directory of Open Access Journals (Sweden)

    K. Kishore Kumar

    2005-07-01

    Full Text Available Several campaigns have been carried out to study the convective systems over Gadanki (13.5° N, 79.2° E, a tropical station in India, using VHF and UHF radars. The height-time sections of several convective systems are investigated in detail to study reflectivity, turbulence and vertical velocity structure. Structure and dynamics of the convective systems are the main objectives of these campaigns. The observed systems are classified into single- and multi-cell systems. It has been observed that most of the convective systems at this latitude are multi-cellular in nature. Simultaneous VHF and UHF radar observations are used to classify the observed precipitating systems as convective, intermediary and stratiform regions. Composite height profiles of vertical velocities in these regions were obtained and the same were compared with the profiles obtained at other geographical locations. These composite profiles of vertical velocity in the convective regions have shown their peaks in the mid troposphere, indicating that the maximum latent heat is being released at those heights. These profiles are very important for numerical simulations of the convective systems, which vary significantly from one geographical location to the other. Keywords. Meteorology and atmospheric dynamics (Mesoscale meteorology; Convective processes – Radio science (Remote sensing

  7. Estimation and prediction of convection-diffusion-reaction systems from point measurement

    NARCIS (Netherlands)

    Vries, D.

    2008-01-01

    Different procedures with respect to estimation and prediction of systems characterized by convection, diffusion and reactions on the basis of point measurement data, have been studied. Two applications of these convection-diffusion-reaction (CDR) systems have been used as a case study of the

  8. Japan-U. S. seminar on magmatic contributions to hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Muffler, L. (U. S. Geological Survey, CA (United States)); Hedenquist, J. (Geological Survey of Japan, Tsukuba (Japan)); Kesler, S. (University of Michigan, MI (United States)); Izawa, E. (Kyushu University, Fukuoka (Japan). Faculty of Engineering)

    1992-08-31

    A multidisciplinary Seminar on Magmatic Contributions to Hydrothermal Systems'' was held at Ebino and Kagoshima at Kyushu, November, 1991. The principal purpose of the Ebino/Kagoshima Seminar was to bring together a small group of individuals which have been conducting active research on magmatic contributions to hydrothermal systems. The Seminar focussed on the porphyry and epithermal ore environments because of the potential to relate these environments to active volcanic and geothermal systems. Disciplines included valcanology, volcanic gas geochemistry, water geochemistry, isotope geochemistry, geochemical modeling, experimental geochemistry, igneous petrology, geothermal geology, economic geology, fluid-inclusion study, geophysics, and physical modeling. This paper summarizes the outline and significance of the Seminar. It was pointed out that understanding magmatic contributions to hydrothermal systems would require augmented experimental investigations, numerical modeling, field studies, and drilling.

  9. An unit commitment model for hydrothermal systems; Um modelo de unit commitment para sistemas hidrotermicos

    Energy Technology Data Exchange (ETDEWEB)

    Franca, Thiago de Paula; Luciano, Edson Jose Rezende; Nepomuceno, Leonardo [Universidade Estadual Paulista (UNESP), Bauru, SP (Brazil). Dept. de Engenharia Eletrica], Emails: ra611191@feb.unesp.br, edson.joserl@uol.com.br, leo@feb.unesp.br

    2009-07-01

    A model of Unit Commitment to hydrothermal systems that includes the costs of start/stop of generators is proposed. These costs has been neglected in a good part of the programming models for operation of hydrothermal systems (pre-dispatch). The impact of the representation of costs in total production costs is evaluated. The proposed model is solved by a hybrid methodology, which involves the use of genetic algorithms (to solve the entire part of the problem) and sequential quadratic programming methods. This methodology is applied to the solution of an IEEE test system. The results emphasize the importance of representation of the start/stop in the generation schedule.

  10. Explicit simulation of a midlatitude Mesoscale Convective System

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, G.D.; Cotton, W.R. [Colorado State Univ., Fort Collins, CO (United States)

    1996-04-01

    We have explicitly simulated the mesoscale convective system (MCS) observed on 23-24 June 1985 during PRE-STORM, the Preliminary Regional Experiment for the Stormscale Operational and Research and Meterology Program. Stensrud and Maddox (1988), Johnson and Bartels (1992), and Bernstein and Johnson (1994) are among the researchers who have investigated various aspects of this MCS event. We have performed this MCS simulation (and a similar one of a tropical MCS; Alexander and Cotton 1994) in the spirit of the Global Energy and Water Cycle Experiment Cloud Systems Study (GCSS), in which cloud-resolving models are used to assist in the formulation and testing of cloud parameterization schemes for larger-scale models. In this paper, we describe (1) the nature of our 23-24 June MCS dimulation and (2) our efforts to date in using our explicit MCS simulations to assist in the development of a GCM parameterization for mesoscale flow branches. The paper is organized as follows. First, we discuss the synoptic situation surrounding the 23-24 June PRE-STORM MCS followed by a discussion of the model setup and results of our simulation. We then discuss the use of our MCS simulation. We then discuss the use of our MCS simulations in developing a GCM parameterization for mesoscale flow branches and summarize our results.

  11. Organic Acids as Hetrotrophic Energy Sources in Hydrothermal Systems

    Science.gov (United States)

    Windman, T. O.; Zolotova, N.; Shock, E.

    2004-12-01

    Many thermophilic microbes are heterotrophs, but little is known about the organic compounds present in hydrothermal ecosystems. More is known about what these organisms will metabolize in lab experiments than what they do metabolize in nature. In an effort to bridge this gap, we have begun to incorporate organic analyses into ongoing research on Yellowstone hydrothermal ecosystems. After filtering at least a liter of hot spring water to minimize contamination, samples were collected into sixty-milliliter serum vials containing ultra-pure phosphoric acid, sodium hydroxide, or benzalkonium chloride. Approximately 80 sites were sampled spanning temperatures from 60 to 90°C and pH values from 2 to 9. Analytical data for organic acid anions (including formate, acetate, lactate, and succinate) were obtained by ion chromatography. Preliminary results indicate that concentrations of organic acids anions range from 5 to 300 ppb. These results can be used with other field and lab data (sulfate, sulfide, nitrate, ammonia, bicarbonate, pH, hydrogen) in thermodynamic calculations to evaluate the amounts of energy available in heterotrophic reactions. Preliminary results of such calculations show that sulfate reduction to sulfide coupled to succinate oxidation to bicarbonate yields about 6 kcal per mole of electrons transferred. When formate oxidation to bicarbonate or hydrogen oxidation to water is coupled to sulfate reduction there is less energy available by approximately a factor of two. A comparison with nitrate reduction to ammonia involving succinate and/or formate oxidation reveals several similarities. Using formate to reduce nitrate can yield about as much energy as nitrate reduction with hydrogen (typically 12 to 14 kcal per mole of electrons transferred), but using succinate can yield more than twice as much energy. In fact, reduction of nitrate with succinate can provide more energy than any of the inorganic nitrate reduction reactions involving sulfur, iron

  12. Evaluation of an assisted convection system for integrated reactors

    International Nuclear Information System (INIS)

    Patruno, Luciano

    2006-01-01

    This work consists of the analyze of changing to an assisted convection system the CAREM-25 nuclear power plant design.The work is focused on the design, construction and measurement of an experimental hydraulic loop which contains a jet pump.There is also a characterization of parameters such as flow rate, hydrostatic pressure, efficiency, velocity profiles and development length using different tools such as theoretical formulations, numeric simulations and experimental data. New set points are found in CAREM thermo hydraulic parameters which take the thermal power to up to 150MW, and the water flow rate to 615 kg/s.To achieve this goals, the use of twelve jet pumps is proposed at a flow rate coefficient of 10.The results on the static pressure provided by the jet pump are calculated theoretically and compared with experimental data.There is an extrapolation of the results to higher flow rate values to be applied to the CAREM-25 design.Concerning the experimental work, the results show a good match on flow rate between the measured data and the theoretical results.There is a reasonable match in the coefficient of flow rate (M), even when the measurement uncertainties are quite high (about 13 %).It is also shown an efficiency measurement, which is up to 14 % [es

  13. Magnetism, planetary rotation and convection in the solar system

    CERN Document Server

    1985-01-01

    On the 6th, 7th' and 8th April 1983, a conference entitled "Magnetism, planetary rotation and convection in the Solar System" was held in the School of Physics at the University of Newcastle upon Tyne. The purpose of the meeting was to celebrate the 60th birthday of Prof. Stanley Keith Runcorn and his, and his students' and associates', several decades of scientific achievement. The social programme, which consisted of excursions in Northumberland and Durham with visits to ancient castles and churches, to Hexham Abbey and Durham Cathedral, and dinners in Newcastle and Durham, was greatly enjoyed by those attending the meeting and by their guests. The success ofthe scientific programme can be judged by this special edition of Geophysical Surveys which is derived mainly from the papers given at the meeting. The story starts in the late 1940s when the question of the origin of the magnetic field of the Earth and such other heavenly bodies as had at that time been discovered as having a magnetic field, was exerci...

  14. Investigating Mesoscale Convective Systems and their Predictability Using Machine Learning

    Science.gov (United States)

    Daher, H.; Duffy, D.; Bowen, M. K.

    2016-12-01

    A mesoscale convective system (MCS) is a thunderstorm region that lasts several hours long and forms near weather fronts and can often develop into tornadoes. Here we seek to answer the question of whether these tornadoes are "predictable" by looking for a defining characteristic(s) separating MCSs that evolve into tornadoes versus those that do not. Using NASA's Modern Era Retrospective-analysis for Research and Applications 2 reanalysis data (M2R12K), we apply several state of the art machine learning techniques to investigate this question. The spatial region examined in this experiment is Tornado Alley in the United States over the peak tornado months. A database containing select variables from M2R12K is created using PostgreSQL. This database is then analyzed using machine learning methods such as Symbolic Aggregate approXimation (SAX) and DBSCAN (an unsupervised density-based data clustering algorithm). The incentive behind using these methods is to mathematically define a MCS so that association rule mining techniques can be used to uncover some sort of signal or teleconnection that will help us forecast which MCSs will result in tornadoes and therefore give society more time to prepare and in turn reduce casualties and destruction.

  15. Identifying bubble collapse in a hydrothermal system using hiddden Markov models

    Science.gov (United States)

    Dawson, Phillip B.; Benitez, M.C.; Lowenstern, Jacob B.; Chouet, Bernard A.

    2012-01-01

    Beginning in July 2003 and lasting through September 2003, the Norris Geyser Basin in Yellowstone National Park exhibited an unusual increase in ground temperature and hydrothermal activity. Using hidden Markov model theory, we identify over five million high-frequency (>15 Hz) seismic events observed at a temporary seismic station deployed in the basin in response to the increase in hydrothermal activity. The source of these seismic events is constrained to within ~100 m of the station, and produced ~3500–5500 events per hour with mean durations of ~0.35–0.45 s. The seismic event rate, air temperature, hydrologic temperatures, and surficial water flow of the geyser basin exhibited a marked diurnal pattern that was closely associated with solar thermal radiance. We interpret the source of the seismicity to be due to the collapse of small steam bubbles in the hydrothermal system, with the rate of collapse being controlled by surficial temperatures and daytime evaporation rates.

  16. Basin scale permeability and thermal evolution of a magmatic hydrothermal system

    Science.gov (United States)

    Taron, J.; Hickman, S. H.; Ingebritsen, S.; Williams, C.

    2013-12-01

    Large-scale hydrothermal systems are potentially valuable energy resources and are of general scientific interest due to extreme conditions of stress, temperature, and reactive chemistry that can act to modify crustal rheology and composition. With many proposed sites for Enhanced Geothermal Systems (EGS) located on the margins of large-scale hydrothermal systems, understanding the temporal evolution of these systems contributes to site selection, characterization and design of EGS. This understanding is also needed to address the long-term sustainability of EGS once they are created. Many important insights into heat and mass transfer within natural hydrothermal systems can be obtained through hydrothermal modeling assuming that stress and permeability structure do not evolve over time. However, this is not fully representative of natural systems, where the effects of thermo-elastic stress changes, chemical fluid-rock interactions, and rock failure on fluid flow and thermal evolution can be significant. The quantitative importance of an evolving permeability field within the overall behavior of a large-scale hydrothermal system is somewhat untested, and providing such a parametric understanding is one of the goals of this study. We explore the thermal evolution of a sedimentary basin hydrothermal system following the emplacement of a magma body. The Salton Sea geothermal field and its associated magmatic system in southern California is utilized as a general backdrop to define the initial state. Working within the general framework of the open-source scientific computing initiative OpenGeoSys (www.opengeosys.org), we introduce full treatment of thermodynamic properties at the extreme conditions following magma emplacement. This treatment utilizes a combination of standard Galerkin and control-volume finite elements to balance fluid mass, mechanical deformation, and thermal energy with consideration of local thermal non-equilibrium (LTNE) between fluids and solids

  17. System and process for efficient separation of biocrudes and water in a hydrothermal liquefaction system

    Science.gov (United States)

    Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Oyler, James R.; Rotness, Jr, Leslie J.; Schmidt, Andrew J.; Zacher, Alan H.

    2016-08-02

    A system and process are described for clean separation of biocrudes and water by-products from hydrothermal liquefaction (HTL) product mixtures of organic and biomass-containing feedstocks at elevated temperatures and pressures. Inorganic compound solids are removed prior to separation of biocrude and water by-product fractions to minimize formation of emulsions that impede separation. Separation may be performed at higher temperatures that reduce heat loss and need to cool product mixtures to ambient. The present invention thus achieves separation efficiencies not achieved in conventional HTL processing.

  18. Constraints on the Lost City Hydrothermal System from borehole thermal data; 3-D models of heat flow and hydrothermal circulation in an oceanic core complex.

    Science.gov (United States)

    Titarenko, S.; McCaig, A. M.

    2014-12-01

    A perennial problem in near-ridge hydrothermal circulation is that the only directly measurable data to test models is often vent fluid temperature. Surface heat flow measurements may be available but without the underlying thermal structure it is not known if they are transient and affected by local hydrothermal flow, or conductive. The Atlantis Massif oceanic core complex at 30 °N on the mid-Atlantic Ridge, offers a unique opportunity to better constrain hydrothermal circulation models. The temperature profile in gabbroic rocks of IODP Hole 1309D was measured in IODPExpedition 340T, and found to be near-conductive, but with a slight inflexion at ~750 mbsf indicating downward advection of fluid above that level. The lack of deep convection is especially remarkable given that the long-lived Lost City Hydrothermal Field (LCHF) is located only 5km to the south. We have modelled hydrothermal circulation in the Massif using Comsol Multiphysics, comparing 2-D and 3-D topographic models and using temperature-dependent conductivity to give the best estimate of heatflow into the Massif. We can constrain maximum permeability in gabbro below 750 mbsf to 5e-17 m2. The thermal gradient in the upper part of the borehole can be matched with a permeability of 3e-14 m2 in a 750 m thick layer parallel to the surface of the massif, with upflow occurring in areas of high topography and downflow at the location of the borehole. However in 3-D the precise flow pattern is quite model dependent, and the thermal structure can be matched either by downflow centred on the borehole at lower permeability or centred a few hundred metres from the borehole at higher permeability. The borehole gradient is compatible with the longevity (>120 kyr) and outflow temperature (40-90 °C) of the LCHF either with a deep more permeable (1e-14 m2 to 1e-15 m2) domain beneath the vent site in 2-D or a permeable fault slot 500 to 1000m wide and parallel to the transform fault in 3-D. In both cases topography

  19. Large-scale thermal convection of viscous fluids in a faulted system: 3D test case for numerical codes

    Science.gov (United States)

    Magri, Fabien; Cacace, Mauro; Fischer, Thomas; Kolditz, Olaf; Wang, Wenqing; Watanabe, Norihiro

    2017-04-01

    Earth Sciences, 67(2), 589-599. Diersch, H. J, 2014. FEFLOW Finite Element Modeling of Flow, Mass and Heat Transport in Porous and Fractured Media, Springer-Verlag Berlin Heidelberg, ISBN 978-3-642-38738-8. Gaston D., Newman C., Hansen G., Lebrun-Grandie D, 2009. MOOSE: A parallel solution framework for coupled systems of nonlinear equations. Nucl. Engrg. Design, 239, 1,768-1778 Magri, F., Möller, S., Inbar, N., Möller, P., Raggad, M., Rödiger, T., Rosenthal, E., Siebert, C., 2016. 2D and 3D coexisting modes of thermal convection in fractured hydrothermal systems - Implications for transboundary flow in the Lower Yarmouk Gorge. Marine and Petroleum Geology 78, 750-758, DOI: /10.1016/j.marpetgeo.2016.10.002 Malkovsky, V. I., Magri, F., 2016. Thermal convection of temperature-dependent viscous fluids within three-dimensional faulted geothermal systems: estimation from linear and numerical analyses, Water Resour. Res., 52, 2855-2867, DOI:10.1002/2015WR018001.

  20. Assessment of operation reserves in hydrothermal electric systems with high wind generation

    NARCIS (Netherlands)

    Ramos, Andres; Rivier, Michel; García-González, Javier; Latorre, Jesus M.; Morales Espana, G.

    2016-01-01

    In this paper, we propose a method to analyze the amount of operation reserves procured in a system based on two stages. The first stage is a detailed hourly unit commitment and the second stage is a simulation model with a shorter time period. The method is applied to the Spanish hydrothermal

  1. Caldera unrest driven by CO2-induced drying of the deep hydrothermal system.

    Science.gov (United States)

    Moretti, R; Troise, C; Sarno, F; De Natale, G

    2018-05-29

    Interpreting volcanic unrest is a highly challenging and non-unique problem at calderas, since large hydrothermal systems may either hide or amplify the dynamics of buried magma(s). Here we use the exceptional ground displacement and geochemical datasets from the actively degassing Campi Flegrei caldera (Southern Italy) to show that ambiguities disappear when the thermal evolution of the deep hydrothermal system is accurately tracked. By using temperatures from the CO 2 -CH 4 exchange of 13 C and thermodynamic analysis of gas ascending in the crust, we demonstrate that after the last 1982-84 crisis the deep hydrothermal system evolved through supercritical conditions under the continuous isenthalpic inflow of hot CO 2 -rich gases released from the deep (~8 km) magma reservoir of regional size. This resulted in the drying of the base of the hot hydrothermal system, no more buffered along the liquid-vapour equilibrium, and excludes any shallow arrival of new magma, whose abundant steam degassing due to decompression would have restored liquid-vapour equilibrium. The consequent CO 2 -infiltration and progressive heating of the surrounding deforming rock volume cause the build-up of pore pressure in aquifers, and generate the striking temporal symmetry that characterizes the ongoing uplift and the post-1984 subsidence, both originated by the same but reversed deformation mechanism.

  2. Mineralization and hydrothermal alteration of the Tajroud vein system, south of Neyshabour

    Directory of Open Access Journals (Sweden)

    Mohsen Alikhani Banghani

    2013-10-01

    Full Text Available The Tajroud vein system is located 190 km southwest of Mashhad, and in the southern part of the Sabzevar zone. The vein host rocks consist of Eocene intermediate to silicic volcanic rocks. The mineralization occurs as open space filling, taking place as veins, veinlets and hydrothermal breccias. Based on field geology and textural evidence, three main stages of mineralization were identified. Stage I mainly contains quartz, pyrite, chalcopyrite and magnetite. Stage II, which has the same mineral assemblage as stage I, is the most important stage in terms of volume. Finally, stage III is characterized by repetitive quartz and calcite banding with negligible amounts of sulfide minerals. Hydrothermal alteration is developed around the veins and tends to be more intense in the vicinity of the veins. The plot of the Ishikawa alteration index (AI versus chlorite-carbonate-pyrite index (CCPI, known as alteration box plot, displays three main alteration trends. The hydrothermal alteration assemblage of quartz, adularia, chlorite, illite, calcite, and epidote that envelops the Tajroud vein system formed from the upwelling of near-neutral to weakly alkaline hydrothermal solutions. The mineralogic, alteration and geochemical characteristics of the studied area and comparison with epithermal ore deposits indicate that the Tajroud vein system represents an epithermal system of low-sulfidation type.

  3. Detection of Abiotic Methane in Terrestrial Continental Hydrothermal Systems: Implications for Methane on Mars

    Science.gov (United States)

    Socki, Richard A.; Niles, Paul B.; Gibson, Everett K., Jr.; Romanek, Christopher S.; Zhang, Chuanlun L.; Bissada, Kadry K.

    2008-01-01

    The recent detection of methane in the Martian atmosphere and the possibility that its origin could be attributed to biological activity, have highlighted the importance of understanding the mechanisms of methane formation and its usefulness as a biomarker. Much debate has centered on the source of the methane in hydrothermal fluids, whether it is formed biologically by microorganisms, diagenetically through the decomposition of sedimentary organic matter, or inorganically via reduction of CO2 at high temperatures. Ongoing research has now shown that much of the methane present in sea-floor hydrothermal systems is probably formed through inorganic CO2 reduction processes at very high temperatures (greater than 400 C). Experimental results have indicated that methane might form inorganically at temperatures lower still, however these results remain controversial. Currently, methane in continental hydrothermal systems is thought to be formed mainly through the breakdown of sedimentary organic matter and carbon isotope equilibrium between CO2 and CH4 is thought to be rarely present if at all. Based on isotopic measurements of CO2 and CH4 in two continental hydrothermal systems, we suggest that carbon isotope equilibration exists at temperatures as low as 155 C. This would indicate that methane is forming through abiotic CO2 reduction at lower temperatures than previously thought and could bolster arguments for an abiotic origin of the methane detected in the martian atmosphere.

  4. Thermodynamic and physico-chemical fluctuations in hydrothermal systems suitable for the geological cradle of life

    Science.gov (United States)

    Kompanichenko, Vladimir

    Thermodynamic and physico-chemical fluctuations in the medium seem are the necessary factor for the origin of life. Fluctuations are usual phenomena in hydrothermal systems including their outcrops in ocean or terrestrial groundwater aquifers. Investigation of the fluctuations regimes in natural hydrothermal systems can be used in advanced laboratory experiments on prebiotic organic synthesis under changeable conditions. To characterize a scale of the thermodynamic and physic-chemical fluctuations four hydrothermal systems were explored: several terrestrial hydrothermal systems, primarily on the Russian Far East. Temperature of water and water-steam mixture (from boreholes) in Mutnovsky and Pauzhetsky hydrothermal fields (Kamchatka peninsula) ranges from less than 100 o C up to 240 o C. Water from Kuldur thermal basin (in-tracontinental part of the Russian Far East) is characterized with the lower temperature: 60-70 o C. Data of monitoring of pressure, temperature and some chemical parameters in the boreholes of these fields were mathematically processed. Periods of long-range macrofluctuations of pres-sure and temperature in Mutnovsky and Kuldur fields are 2-4.5 months, maximum amplitudes of temperature in the wells' orifices are 53o C and 9 o C correspondingly, maximum amplitude of pressure in Mutnovsky field 34 bars. Periods of minioscillations are from 10 to 70 minutes in Mutnovsky and Pauzhetsky fields, average amplitudes of pressure are 0.2-0.7 bars. These data are comparable with similar data from Mura basin in Slovenia: amplitudes of temperature and pH minioscillations are about 1-2o C and 0.2 correspondingly; there exists strict positive correlation of temperature with pH, K+, Na+, Ca2+, HCO3-, SO42-, Cl-, F-, but concentra-tions of Mg2+, NH4+, CO2 change independently (Kralj, 2000).. The general conclusion is that minifluctuations of thermodynamic and physic-chemical parameters in hydrothermal sys-tems are usual phenomenon. From time to time the

  5. Dynamical System Analysis of Thermal Convection in a Horizontal Layer of Nanofluids Heated from Below

    Directory of Open Access Journals (Sweden)

    J. M. Jawdat

    2012-01-01

    Full Text Available The effect of nanofluids on chaotic convection in a fluid layer heated from below was studied in this paper for low Prandtl number based on the theory of dynamical systems. A low-dimensional, Lorenz-like model was obtained using Galerkin-truncated approximations. The fourth-order Runge-Kutta method was employed to solve the nonlinear system. The results show that inhibition of chaotic convection can be observed when using nanofluids.

  6. Experimental StudyHigh Altitude Forced Convective Cooling of Electromechanical Actuation Systems

    Science.gov (United States)

    2016-01-01

    34 Massachusetts Institute of Technology , 1989. [3] FedBizOps.Gov, " Integrated Vehicle Energy Technology (INVENT) Development Program for the 6th...AFRL-RQ-WP-TR-2016-0043 EXPERIMENTAL STUDY—HIGH ALTITUDE FORCED CONVECTIVE COOLING OF ELECTROMECHANICAL ACTUATION SYSTEMS Evan M. Racine...TITLE AND SUBTITLE EXPERIMENTAL STUDY—HIGH ALTITUDE FORCED CONVECTIVE COOLING OF ELECTROMECHANICAL ACTUATION SYSTEMS 5a. CONTRACT NUMBER In-house

  7. Water-rock interactions in discharge areas of Xiangshan Fossil hydrothermal system

    International Nuclear Information System (INIS)

    Zhou, Wenbin

    1992-01-01

    Xiangshan Fossil hydrothermal system is located within a volcanic basin of south-eastern China. The fact that most metal mineralizations were found in the discharge areas of the fossil hydrothermal system shows that the discharge areas were special geochemical fields. This paper discusses some important water-rock interactions in the discharge areas of Xiangshan fossil hydrothermal system. When the fluids circulating in the deep section of the hydrothermal system went upward to the discharge area, the physico-chemical conditions under which the fluids were saturated changed so considerably that the original physico-chemical equilibria were broken. Consequently, the fluids tended to move to new equilibrium by means of regulating their chemical compositions. Temperature and pressures of the fluids could be declined greatly in discharge area; the difference of temperature and pressure are determined to be 100--150 C and 1--2 x 10 7 Pa. As a result, a large amount of CO 2 in solution escaped from the fluids in the discharge area, and UO 2 (CO 3 ) n 2(1-n) , stable in CO 2 -rich solutions, could be decomposed into UUO 2 2+ , which could be easily reduced into pitchblende associated by calcite and hematite. The pH values for the fluids tended to increase with the CO 2 escaping, however, the interactions between the hydrothermal fluids and the wall rocks (dominantly aluminosilicate) served as the buffers for the pH, and regulated the pH value around neutral point. The buffer effect was of great importance to uranium mineralization. In addition, isotope exchangements between the fluids and rocks took place extensively

  8. Energy landscapes shape microbial communities in hydrothermal systems on the Arctic Mid-Ocean Ridge.

    Science.gov (United States)

    Dahle, Håkon; Økland, Ingeborg; Thorseth, Ingunn H; Pederesen, Rolf B; Steen, Ida H

    2015-07-01

    Methods developed in geochemical modelling combined with recent advances in molecular microbial ecology provide new opportunities to explore how microbial communities are shaped by their chemical surroundings. Here, we present a framework for analyses of how chemical energy availability shape chemotrophic microbial communities in hydrothermal systems through an investigation of two geochemically different basalt-hosted hydrothermal systems on the Arctic Mid-Ocean Ridge: the Soria Moria Vent field (SMVF) and the Loki's Castle Vent Field (LCVF). Chemical energy landscapes were evaluated through modelling of the Gibbs energy from selected redox reactions under different mixing ratios between seawater and hydrothermal fluids. Our models indicate that the sediment-influenced LCVF has a much higher potential for both anaerobic and aerobic methane oxidation, as well as aerobic ammonium and hydrogen oxidation, than the SMVF. The modelled energy landscapes were used to develop microbial community composition models, which were compared with community compositions in environmental samples inside or on the exterior of hydrothermal chimneys, as assessed by pyrosequencing of partial 16S rRNA genes. We show that modelled microbial communities based solely on thermodynamic considerations can have a high predictive power and provide a framework for analyses of the link between energy availability and microbial community composition.

  9. Relative Importance of Chemoautotrophy for Primary Production in a Light Exposed Marine Shallow Hydrothermal System

    Directory of Open Access Journals (Sweden)

    Gonzalo V. Gomez-Saez

    2017-04-01

    Full Text Available The unique geochemistry of marine shallow-water hydrothermal systems promotes the establishment of diverse microbial communities with a range of metabolic pathways. In contrast to deep-sea vents, shallow-water vents not only support chemosynthesis, but also phototrophic primary production due to the availability of light. However, comprehensive studies targeting the predominant biogeochemical processes are rare, and consequently a holistic understanding of the functioning of these ecosystems is currently lacking. To this end, we combined stable isotope probing of lipid biomarkers with an analysis of the bacterial communities to investigate if chemoautotrophy, in parallel to photoautotrophy, plays an important role in autotrophic carbon fixation and to identify the key players. The study was carried out at a marine shallow-water hydrothermal system located at 5 m water depth off Dominica Island (Lesser Antilles, characterized by up to 55°C warm hydrothermal fluids that contain high amounts of dissolved Fe2+. Analysis of the bacterial diversity revealed Anaerolineae of the Chloroflexi as the most abundant bacterial class. Furthermore, the presence of key players involved in iron cycling generally known from deep-sea hydrothermal vents (e.g., Zetaproteobacteria and Geothermobacter, supported the importance of iron-driven redox processes in this hydrothermal system. Uptake of 13C-bicarbonate into bacterial fatty acids under light and dark conditions revealed active photo- and chemoautotrophic communities, with chemoautotrophy accounting for up to 65% of the observed autotrophic carbon fixation. Relatively increased 13C-incorporation in the dark allowed the classification of aiC15:0, C15:0, and iC16:0 as potential lipid biomarkers for bacterial chemoautotrophy in this ecosystem. Highest total 13C-incorporation into fatty acids took place at the sediment surface, but chemosynthesis was found to be active down to 8 cm sediment depth. In conclusion

  10. Reaction chemistry of nitrogen species in hydrothermal systems: Simple reactions, waste simulants, and actual wastes

    International Nuclear Information System (INIS)

    Dell'Orco, P.; Luan, L.; Proesmans, P.; Wilmanns, E.

    1995-01-01

    Results are presented from hydrothermal reaction systems containing organic components, nitrogen components, and an oxidant. Reaction chemistry observed in simple systems and in simple waste simulants is used to develop a model which presents global nitrogen chemistry in these reactive systems. The global reaction path suggested is then compared with results obtained for the treatment of an actual waste stream containing only C-N-0-H species

  11. Development of Mitsui/Juelich Incineration System and hydro-thermal ash solidification

    International Nuclear Information System (INIS)

    Suzuki, S.; Kamada, S.; Nakamori, Y.; Katakura, M.; Yamazaki, N.

    1988-01-01

    This paper summarizes the developing program for Mitsui/Juelich Incinerated System combined with Hydrothermal ash solidification. The system is an integrated one and capable for volume reduction of various kind of radioactive waste and safe disposal of residual incinerator ash. The system also has an advantage of reducing construction and operation cost. An outline of the incineration plant is also presented in this paper

  12. Sparse identification of a predator-prey system from simulation data of a convection model

    DEFF Research Database (Denmark)

    Dam, Magnus; Brøns, Morten; Rasmussen, Jens Juul

    2017-01-01

    of a convection problem. A convection model with a pressure source centered at the inner boundary models the edge dynamics of a magnetically confined plasma. The convection problem undergoes a sequence of bifurcations as the strength of the pressure source increases. The time evolution of the energies......The use of low-dimensional dynamical systems as reduced models for plasma dynamics is useful as solving an initial value problem requires much less computational resources than fluid simulations. We utilize a data-driven modeling approach to identify a reduced model from simulation data...

  13. Thermochemical convection in porous media : an application to hydrothermal systems and magmetic intrusions

    NARCIS (Netherlands)

    Schoofs, C.A.

    1999-01-01

    The motion of aqueous and magmatic liquids has a large influence on the evolution of the cooling and chemically differentiating Earth. In many geological environments, these fluids percolate through the pores and fractures of a solid matrix, which is composed of (un)conso-lidated rocks or

  14. Origin of the pre-tropical storm Debby (2006) African easterly wave-mesoscale convective system

    Science.gov (United States)

    Lin, Yuh-Lang; Liu, Liping; Tang, Guoqing; Spinks, James; Jones, Wilson

    2013-05-01

    The origins of the pre-Debby (2006) mesoscale convective system (MCS) and African easterly wave (AEW) and their precursors were traced back to the southwest Arabian Peninsula, Asir Mountains (AS), and Ethiopian Highlands (EH) in the vicinity of the ITCZ using satellite imagery, GFS analysis data and ARW model. The sources of the convective cloud clusters and vorticity perturbations were attributed to the cyclonic convergence of northeasterly Shamal wind and the Somali jet, especially when the Mediterranean High shifted toward east and the Indian Ocean high strengthened and its associated Somali jet penetrated farther to the north. The cyclonic vorticity perturbations were strengthened by the vorticity stretching associated with convective cloud clusters in the genesis region—southwest Arabian Peninsula. A conceptual model was proposed to explain the genesis of convective cloud clusters and cyclonic vorticity perturbations preceding the pre-Debby (2006) AEW-MCS system.

  15. The fossil hydrothermal system from Volta Grande, Lavras do Sul, RS. Part 2: Geochemical of chlorites

    International Nuclear Information System (INIS)

    Mexias, A.S.; Formoso, M.L.L.; Mattos, I.C.; Gomes, M.E.B.; Meunier, A.; Beaufort, D.

    1990-01-01

    Chlorites related to propylitic phyllic processes in Fossil Hydrothermal System of Volta Grande/RS, quite similar to porphyry copper type deposit, were studied. Electron probe analysis in chlorites and chemical total rock analysis made the study of macro and micro system possible. The geochemical study of the micro system enable to characterize the inactive and active flow regimes of hydrothermal process in propylitic and phyllic, respectively. Geo-thermometric data, at least qualitatively, indicate that the phyllic alteration is the same or slightly higher than propylitic alteration. The detailed study of the composition of chlorites in micro system permitted to know the diadochic replacement of elements, especially in chloritization of biotite, in which the mobility of Al 3+ (at least in mineral scale) is possible under constant volume and Ti 4+ . The rocks were analysed by absorption spectroscopy, X-ray fluorescence analysis and gravimetry. (author)

  16. Corrosion in lithium-stainless steel thermal-convection systems

    International Nuclear Information System (INIS)

    Tortorelli, P.F.; DeVan, J.H.; Selle, J.E.

    1980-01-01

    The corrosion of types 304L and 316 austenitic stainless steel by flowing lithium was studied in thermal-convection loops operated at 500 to 650 0 C. Both weight and compositional changes were measured on specimens distributed throughout each loop and were combined with metallographic examinations to evaluate the corrosion processes. The corrosion rate and mass transfer characteristics did not significantly differ between the two austenitic stainless steels. Addition of 500 or 1700 wt ppM N to purified lithium did not increase the dissolution rate or change the attack mode of type 316 stainless steel. Adding 5 wt % Al to the lithium reduced the weight loss of this steel by a factor of 5 relative to a pure lithium-thermal-convection loop

  17. Analysis of Summertime Convective Initiation in Central Alabama Using the Land Information System

    Science.gov (United States)

    James, Robert S.; Case, Jonathan L.; Molthan, Andrew L.; Jedlovec, Gary J.

    2011-01-01

    During the summer months in the southeastern United States, convective initiation presents a frequent challenge to operational forecasters. Thunderstorm development has traditionally been referred to as random due to their disorganized, sporadic appearance and lack of atmospheric forcing. Horizontal variations in land surface characteristics such as soil moisture, soil type, land and vegetation cover could possibly be a focus mechanism for afternoon convection during the summer months. The NASA Land Information System (LIS) provides a stand-alone land surface modeling framework that incorporates these varying soil and vegetation properties, antecedent precipitation, and atmospheric forcing to represent the soil state at high resolution. The use of LIS as a diagnostic tool may help forecasters to identify boundaries in land surface characteristics that could correlate to favored regions of convection initiation. The NASA Shortterm Prediction Research and Transition (SPoRT) team has been collaborating with the National Weather Service Office in Birmingham, AL to help incorporate LIS products into their operational forecasting methods. This paper highlights selected convective case dates from summer 2009 when synoptic forcing was weak, and identifies any boundaries in land surface characteristics that may have contributed to convective initiation. The LIS output depicts the effects of increased sensible heat flux from urban areas on the development of convection, as well as convection along gradients in land surface characteristics and surface sensible and latent heat fluxes. These features may promote mesoscale circulations and/or feedback processes that can either enhance or inhibit convection. With this output previously unavailable to operational forecasters, LIS provides a new tool to forecasters in order to help eliminate the randomness of summertime convective initiation.

  18. Water-rock interaction in the magmatic-hydrothermal system of Nisyros Island (Greece)

    Science.gov (United States)

    Ambrosio, Michele; Doveri, Marco; Fagioli, Maria Teresa; Marini, Luigi; Principe, Claudia; Raco, Brunella

    2010-04-01

    In this work, we investigated the water-rock interaction processes taking place in the hydrothermal reservoir of Nisyros through both: (1) a review of the hydrothermal mineralogy encountered in the deep geothermal borehole Nisyros-2; and (2) a comparison of the analytically-derived redox potentials and acidities of fumarolic-related liquids, with those controlled by redox buffers and pH buffers, involving hydrothermal mineral phases. The propylitic zone met in the deep geothermal borehole Nisyros-2, from 950 to 1547 m (total depth), is characterised by abundant, well crystallised epidote, adularia, albite, quartz, pyrite, chlorite, and sericite-muscovite, accompanied by less abundant anhydrite, stilpnomelane, wairakite, garnet, tremolite and pyroxene. These hydrothermal minerals were produced in a comparatively wide temperature range, from 230 to 300 °C, approximately. Hydrothermal assemblages are well developed from 950 to 1360 m, whereas they are less developed below this depth, probably due to low permeability. Based on the RH values calculated for fumarolic gases and for the deep geothermal fluids of Nisyros-1 and Nisyros-2 wells, redox equilibrium with the (FeO)/(FeO 1.5) rock buffer appears to be closely attained throughout the hydrothermal reservoir of Nisyros. This conclusion may be easily reconciled with the nearly ubiquitous occurrence of anhydrite and pyrite, since RH values controlled by coexistence of anhydrite and pyrite can be achieved by gas separation. The pH of the liquids feeding the fumarolic vents of Stephanos and Polybote Micros craters was computed, by means of the EQ3 code, based on the Cl- δD relationship which is constrained by the seawater-magmatic water mixing occurring at depth in the hydrothermal-magmatic system of Nisyros. The temperature dependence of analytically-derived pH values for the reservoir liquids feeding the fumarolic vents of Stephanos and Polybote Micros craters suggests that some unspecified pH buffer fixes the

  19. Field-based tests of geochemical modeling codes: New Zealand hydrothermal systems

    International Nuclear Information System (INIS)

    Bruton, C.J.; Glassley, W.E.; Bourcier, W.L.

    1993-12-01

    Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions

  20. Field-based tests of geochemical modeling codes usign New Zealand hydrothermal systems

    International Nuclear Information System (INIS)

    Bruton, C.J.; Glassley, W.E.; Bourcier, W.L.

    1994-06-01

    Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions

  1. Multiobjective CVaR Optimization Model and Solving Method for Hydrothermal System Considering Uncertain Load Demand

    Directory of Open Access Journals (Sweden)

    Zhongfu Tan

    2015-01-01

    Full Text Available In order to solve the influence of load uncertainty on hydrothermal power system operation and achieve the optimal objectives of system power generation consumption, pollutant emissions, and first-stage hydropower station storage capacity, this paper introduced CVaR method and built a multiobjective optimization model and its solving method. In the optimization model, load demand’s actual values and deviation values are regarded as random variables, scheduling objective is redefined to meet confidence level requirement and system operation constraints and loss function constraints are taken into consideration. To solve the proposed model, this paper linearized nonlinear constraints, applied fuzzy satisfaction, fuzzy entropy, and weighted multiobjective function theories to build a fuzzy entropy multiobjective CVaR model. The model is a mixed integer linear programming problem. Then, six thermal power plants and three cascade hydropower stations are taken as the hydrothermal system for numerical simulation. The results verified that multiobjective CVaR method is applicable to solve hydrothermal scheduling problems. It can better reflect risk level of the scheduling result. The fuzzy entropy satisfaction degree solving algorithm can simplify solving difficulty and get the optimum operation scheduling scheme.

  2. Fault-controlled development of shallow hydrothermal systems: Structural and mineralogical insights from the Southern Andes

    Science.gov (United States)

    Roquer, T.; Arancibia, G.; Rowland, J. V.; Iturrieta, P. C.; Morata, D.; Cembrano, J. M.

    2017-12-01

    Paleofluid-transporting systems can be recognized as meshes of fracture-filled veins in eroded zones of extinct hydrothermal systems. Here we conducted meso-microstructural analysis and mechanical modeling from two exhumed exposures of the faults governing regional tectonics of the Southern Andes: the Liquiñe-Ofqui Fault System (LOFS) and the Andean Transverse Faults (ATF). A total of 107 fractures in both exposures were analyzed. The ATF specific segment shows two tectonic solutions that can be modeled as Andersonian and non-Andersonian tectonic regimes: (1) shear (mode II/III) failure occurs at differential stresses > 28 MPa and fluid pressures 85-98% lithostatic in the non-Andersonian regime. Additionally, the LOFS exposure cyclically fails in extension (mode I) or extension + shear (modes I + II/III) in the Andersonian regime, at differential stresses 40-80% lithostatic. In areas of spatial interaction between ATF and LOFS, these conditions might favor: (1) the storage of overpressured fluids in hydrothermal systems associated with the ATF faults, and (2) continuous fluid flow through vertical conduits in the LOFS faults. These observations suggest that such intersections are highly probable locations for concentrated hydrothermal activity, which must be taken into consideration for further geothermal exploration. ACKNOWLEDGEMENTS. PhD CONICYT grants, Centro de Excelencia en Geotermia de los Andes (CEGA-FONDAP/CONICYT Project #15090013), FONDECYT Project #1130030 and Project CONICYT REDES #140036.

  3. Solubility limits in Mn–Mg ferrites system under hydrothermal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hemeda, O.M., E-mail: omhemeda@yahoo.co.uk [Physics Department, Faculty of Science, Tanta University, Tanta (Egypt); Mostafa, N.Y. [Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt); Faculty of Science, Taif University, PO Box 888, Al-Haweiah, Taif (Saudi Arabia); Abd Elkader, O.H. [Electron Microscope and Thin Films Department, National Research Center, Dokki 12622, Cairo (Egypt); Electron Microscope Unit, Zoology Department, King Saud University, Riyadh 11451 (Saudi Arabia); Ahmed, M.A. [Physics Department, Faculty of Science, Al Azhar University, Nasr City, Cairo (Egypt)

    2014-09-01

    In the present investigation, we successfully synthesized a pure MnFe{sub 2}O{sub 4} ferrite by the hydrothermal method. Moreover, the effect of Mg ion content on the formation of Mn{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} particles (with x varying from 0.1 to 1.0) was also investigated using XRD, SEM, TEM and Mossbauer Spectroscopy. Phases formed in the system Mn{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4}; 0.0≤x≤1.0 were investigated under hydrothermal conditions at 453 K.The produced phases were characterized by X-ray diffraction, Scanning, transmission microscopy and Mossbauer spectroscopy. The information of composition, cation distribution in the spinel structure and the particle size of the products were obtained. The spinel ferrites; Mn{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} were formed in the range 0.0≤x≤0.3. However, sample with x>0.3 showed semi-crystalline magnesium hydroxide (Mg(OH){sub 2}) and hematite (Fe{sub 2}O{sub 3}) beside the ferrite phase. For x=1.0, only magnesium hydroxide and hematite are formed without any ferrites. Particles of uniform size around 10–20 nm were obtained in the spinel structure of Mn{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} with x=0.0 and 0.1. The corresponding average crystallite size for each sample was 40.3 nm and 39.2 nm respectively. In addition, the Mossbauer spectra were analyzed into two subspectra, one for the tetrahedral A-site and the other for the octahedral B-site. The Mossbauer parameters were determined and discussed for the studied system. The cation distribution was estimated from the analysis of the Mossbauer spectra as well as the X-ray diffraction patterns. The results showed that Mg ions occupy mainly B-site while both Mn and Fe ions are distributed between A- and B-sites. - Highlights: • Mossbauer characterization of Mg–Mn ferrite prepared by hydrothermal route. • X-ray powder diffraction analysis of Mg–Mn ferrite prepared by hydrothermal route. • Solubility limit of MgMn ferrite under

  4. Short term economic emission power scheduling of hydrothermal energy systems using improved water cycle algorithm

    International Nuclear Information System (INIS)

    Haroon, S.S.; Malik, T.N.

    2017-01-01

    Due to the increasing environmental concerns, the demand of clean and green energy and concern of atmospheric pollution is increasing. Hence, the power utilities are forced to limit their emissions within the prescribed limits. Therefore, the minimization of fuel cost as well as exhaust gas emissions is becoming an important and challenging task in the short-term scheduling of hydro-thermal energy systems. This paper proposes a novel algorithm known as WCA-ER (Water Cycle Algorithm with Evaporation Rate) to inspect the short term EEPSHES (Economic Emission Power Scheduling of Hydrothermal Energy Systems). WCA has its ancestries from the natural hydrologic cycle i.e. the raining process forms streams and these streams start flowing towards the rivers which finally flow towards the sea. The worth of WCA-ER has been tested on the standard economic emission power scheduling of hydrothermal energy test system consisting of four hydropower and three thermal plants. The problem has been investigated for the three case studies (i) ECS (Economic Cost Scheduling), (ii) ES (Economic Emission Scheduling) and (iii) ECES (Economic Cost and Emission Scheduling). The results obtained show that WCA-ER is superior to many other methods in the literature in bringing lower fuel cost and emissions. (author)

  5. Volcano-hydrothermal system and activity of Sirung volcano (Pantar Island, Indonesia)

    Science.gov (United States)

    Caudron, Corentin; Bernard, Alain; Murphy, Sam; Inguaggiato, Salvatore; Gunawan, Hendra

    2018-05-01

    Sirung is a frequently active volcano located in the remote parts of Western Timor (Indonesia). Sirung has a crater with several hydrothermal features including a crater lake. We present a timeseries of satellite images of the lake and chemical and isotope data from the hyperacid hydrothermal system. The fluids sampled in the crater present the typical features of hyperacidic systems with high TDS, low pH and δ34SHSO4-δ34SS0 among the highest for such lakes. The cations concentrations are predominantly controlled by the precipitation of alunite, jarosite, silica phases, native sulfur and pyrite which dominate the shallow portions of the hydrothermal system. These minerals may control shallow sealing processes thought to trigger phreatic eruptions elsewhere. Sparse Mg/Cl and SO4/Cl ratios and lake parameters derived from satellite images suggest gradual increase in heat and gas flux, most likely SO2-rich, prior to the 2012 phreatic eruption. An acidic river was sampled 8 km far from the crater and is genetically linked with the fluids rising toward the active crater. This river would therefore be a relevant target for future remote monitoring purposes. Finally, several wells and springs largely exceeded the World Health Organization toxicity limits in total arsenic and fluoride.

  6. Evaporative and Convective Instabilities for the Evaporation of a Binary Mixture in a Bilayer System

    Science.gov (United States)

    Guo, Weidong; Narayanan, Ranga

    2006-11-01

    Evaporative convection in binary mixtures arises in a variety of industrial processes, such as drying of paint and coating technology. There have been theories devoted to this problem either by assuming a passive vapor layer or by isolating the vapor fluid dynamics. Previous work on evaporative and convective instabilities in a single component bilayer system suggests that active vapor layers play a major role in determining the instability of the interface. We have investigated the evaporation convection in binary mixtures taking into account the fluid dynamics of both phases. The liquid mixture and its vapor are assumed to be confined between two horizontal plates with a base state of zero evaporation but with linear vertical temperature profile. When the vertical temperature gradient reaches a critical value, the evaporative instability, Rayleigh and Marangoni convection set in. The effects of vapor and liquid depth, various wave numbers and initial composition of the mixture on the evaporative and convective instability are determined. The physics of the instability are explained and detailed comparison is made between the Rayleigh, Marangoni and evaporative convection in pure component and those in binary mixtures.

  7. Upper Troposphere Lower Stratosphere structure during convective systems using GPS radio occultations

    DEFF Research Database (Denmark)

    Biondi, Riccardo

    The deep convective systems play a fundamental role in atmospheric circulation and climate. Thunderstorms and meso-scale convective systems produce fast vertical transport, redistributing water vapor and trace gases and influencing the thermal structure of the upper troposphere and lower...... stratosphere (UTLS) contributing to the troposphere-stratosphere transport and affecting the Earth global circulation and the climate changes. The Global Positioning System (GPS) Radio Occultation (RO) technique enables measurement of atmospheric density structure in any meteorological condition...... to the analysis of tropical storms for the future mission ACES will also be evaluated. Using data from the past and ongoing GPS RO missions we have defined an algorithm to detect the clouds top of the convective systems and their thermal structure. Other satellite and in-situ measurements co-located with GPS ROs...

  8. Plumbing the depths of Yellowstone's hydrothermal system from helicopter magnetic and electromagnetic data

    Science.gov (United States)

    Finn, C.; Bedrosian, P.; Holbrook, W. S.; Auken, E.; Lowenstern, J. B.; Hurwitz, S.; Sims, K. W. W.; Carr, B.; Dickey, K.

    2017-12-01

    Although Yellowstone's iconic hydrothermal systems and lava flows are well mapped at the surface, their groundwater flow systems and thickness are almost completely unknown. In order to track the geophysical signatures of geysers, hot springs, mud pots, steam vents, hydrothermal explosion craters and lava flows at depths to hundreds of meters, we collected helicopter electromagnetic and magnetic (HEM) data. The data cover significant portions of the caldera including a majority of the known thermal areas. HEM data constrain electrical resistivity which is sensitive to groundwater salinity and temperature, phase distribution (liquid-vapor), and clay formed during chemical alteration of rocks. The magnetic data are sensitive to variations in the magnetization of lava flows, faults and hydrothermal alteration. The combination of electromagnetic and magnetic data is ideal for mapping zones of cold fresh water, hot saline water, steam, clay, and altered and unaltered rock. Preliminary inversion of the HEM data indicates very low resistivity directly beneath the northern part of Yellowstone Lake, intersecting with the lake bottom in close correspondence with mapped vents, fractures and hydrothermal explosion craters and are also associated with magnetic lows. Coincident resistivity and magnetic lows unassociated with mapped alteration occur, for example, along the southeast edge of the Mallard Lake dome and along the northeastern edge of Sour Creek Dome, suggesting the presence of buried alteration. Low resistivities unassociated with magnetic lows may relate to hot and/or saline groundwater or thin (<50 m) layers of early lake sediments to which the magnetic data are insensitive. Resistivity and magnetic lows follow interpreted caldera boundaries in places, yet deviate in others. In the Norris-Mammoth Corridor, NNE-SSW trending linear resistivity and magnetic lows align with mapped faults. This pattern of coincident resistivity and magnetic lows may reflect fractures

  9. The conversion of smectite to illite in hydrothermal systems

    International Nuclear Information System (INIS)

    Johnston, R.M.

    1983-06-01

    In natural diagenetic shale systems, smectite converts to illite and mixed-layer illite-smectite in less than a million years at temperatures between 75 degrees C and 200 degrees C. This has raised questions as to the stability of smectite-based bentonite buffers under nuclear waste disposal vault conditions. Experimental and geological evidence indicate that the reaction is dependent on the availability of K + , and that the rate of reaction in K + -poor systems (such as the disposal vault) may be much lower than that observed in shale. The presence of Na + , Ca 2+ and Mg 2+ in the system slows the reaction and may halt it altogether at lower temperatures. Two different reaction mechanisms have been proposed; the evidence for, and implication of, each are discussed

  10. Concentration and distribution of dissolved amino acids in a shallow hydrothermal system, Vulcano Island (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, E.; Skoog, A. [University of Connecticut, Groton, CT (United States). Dept. of Marine Sciences; Amend, J.P. [Washington University, St. Louis, MO (United States). Dept. of Earth and Planetary Sciences

    2004-09-01

    Hydrothermal systems are known to harbour a large number of microorganisms, but the organic chemical composition of the solution that comprises their potential substrate is largely unknown. Concentrations and distributions of dissolved free amino acids (DFAA) and dissolved combined amino acids (DCAA) were determined in fluids from the moderate-temperature (42-89{sup o}C), shallow hydrothermal system on the volcanically active island of Vulcano, Italy. The seven samples represent three different geological settings on the island; shallow ({approx} 1 m) submarine vents, geothermal wells, and seeps in heated beach sediments, in addition to ambient local seawater from the bay, Baia di Levante. All hydrothermal sites, with one exception, had TDAA concentrations that were 3-114 times higher than local seawater in Baia di Levante. There were large similarities in amino acid concentration and composition among samples from the same geological setting. The highest amino acid concentrations were found at sites with acidic and reducing conditions, which also had the largest freshwater component. An unusually high fraction of the TDAA pool was represented by DFAA (33-87%), possibly due to in situ acid hydrolysis of DCAA to DFAA. Both DFAA and DCAA concentrations were correlated to DOC, indicating similar source and sink functions for these pools. The yield of TDAA (TDAA-carbon as fraction of organic carbon) ranged from 2% to 25%, which is high compared with non-hydrothermal settings, and indicates high biological lability. The mole fraction of {beta}-alanine plus {gamma}-aminobutyric acid (% BALA + GABA) was 2-2.7% of TDAA, also indicating high biological lability. Owing to the high over-all amino acid concentrations, the high fraction of DFAAs, and the high biological lability of the organic matter, organic matter in general and amino acids specifically could represent significant carbon and energy sources for archaea and bacteria in this hydrothermal system. The clear

  11. A review of numerical simulation of hydrothermal systems.

    Science.gov (United States)

    Mercer, J.W.; Faust, C.R.

    1979-01-01

    Many advances in simulating single and two-phase fluid flow and heat transport in porous media have recently been made in conjunction with geothermal energy research. These numerical models reproduce system thermal and pressure behaviour and can be used for other heat-transport problems, such as high-level radioactive waste disposal and heat-storage projects. -Authors

  12. Life Cycle of Midlatitude Deep Convective Systems in a Lagrangian Framework

    Science.gov (United States)

    Feng, Zhe; Dong, Xiquan; Xie, Baike; McFarlane, Sally A.; Kennedy, Aaron; Lin, Bing; Minnis, Patrick

    2012-01-01

    Deep Convective Systems (DCSs) consist of intense convective cores (CC), large stratiform rain (SR) regions, and extensive non-precipitating anvil clouds (AC). This study focuses on the evolution of these three components and the factors that affect convective AC production. An automated satellite tracking method is used in conjunction with a recently developed multi-sensor hybrid classification to analyze the evolution of DCS structure in a Lagrangian framework over the central United States. Composite analysis from 4221 tracked DCSs during two warm seasons (May-August, 2010-2011) shows that maximum system size correlates with lifetime, and longer-lived DCSs have more extensive SR and AC. Maximum SR and AC area lag behind peak convective intensity and the lag increases linearly from approximately 1-hour for short-lived systems to more than 3-hours for long-lived ones. The increased lag, which depends on the convective environment, suggests that changes in the overall diabatic heating structure associated with the transition from CC to SR and AC could prolong the system lifetime by sustaining stratiform cloud development. Longer-lasting systems are associated with up to 60% higher mid-tropospheric relative humidity and up to 40% stronger middle to upper tropospheric wind shear. Regression analysis shows that the areal coverage of thick AC is strongly correlated with the size of CC, updraft strength, and SR area. Ambient upper tropospheric wind speed and wind shear also play an important role for convective AC production where for systems with large AC (radius greater than 120-km) they are 24% and 20% higher, respectively, than those with small AC (radius=20 km).

  13. REE controls in ultramafic hosted MOR hydrothermal systems: An experimental study at elevated temperature and pressure

    Science.gov (United States)

    Allen, Douglas E.; Seyfried, W. E.

    2005-02-01

    A hydrothermal experiment involving peridotite and a coexisting aqueous fluid was conducted to assess the role of dissolved Cl - and redox on REE mobility at 400°C, 500 bars. Data show that the onset of reducing conditions enhances the stability of soluble Eu +2 species. Moreover, Eu +2 forms strong aqueous complexes with dissolved Cl - at virtually all redox conditions. Thus, high Cl - concentrations and reducing conditions can combine to reinforce Eu mobility. Except for La, trivalent REE are not greatly affected by fluid speciation under the chemical and physical condition considered, suggesting control by secondary mineral-fluid partitioning. LREE enrichment and positive Eu anomalies observed in fluids from the experiment are remarkably similar to patterns of REE mobility in vent fluids issuing from basalt- and peridotite-hosted hydrothermal systems. This suggests that the chondrite normalized REE patterns are influenced greatly by fluid speciation effects and secondary mineral formation processes. Accordingly, caution must be exercised when using REE in hydrothermal vent fluids to infer REE sources in subseafloor reaction zones from which the fluids are derived. Although vent fluid patterns having LREE enrichment and positive Eu anomalies are typically interpreted to suggest plagioclase recrystallization reactions, this need not always be the case.

  14. Hydrothermal system of the Papandayan Volcano from temperature, self-potential (SP) and geochemical measurements

    Science.gov (United States)

    Byrdina, Svetlana; Revil, André; Gunawan, Hendra; Saing, Ugan B.; Grandis, Hendra

    2017-07-01

    Papandayan volcano in West Java, Indonesia, is characterized by intense hydrothermal activities manifested by numerous fumaroles at three craters or kawah, i.e. Mas, Manuk and Baru. The latter was created after November 2002 phreatic eruption. Since 2011, numerous volcano-tectonic B events are encountered and the volcano was set on alert status on several occasions. The purpose of the present study is to delineate the structure of the summital hydrothermal system from Self-Potential (SP), soil temperature and gas concentrations in the soil (CO2, SO2 and H2S) data. This combination of geophysical and geochemical methods allows identification of the weak permeable zones serving as preferential pathways for hydrothermal circulation and potential candidates to future landslides or flank collapses. This study is an on-going collaborative research project and we plan to conduct electrical resistivity tomography (ERT) and also Induced-Polarization (IP) surveys. Additional data would allow the 3D imaging of the studied area. The IP parameters will be used to characterise and to quantify the degree of alteration of the volcanic rocks as has been shown very recently in the laboratory studies. There are also rocks and soil samples that will undergo laboratory analyses at ISTerre for IP and complex resistivity parameters at the sample scale that will help to interpret the survey results.

  15. Identifying bubble collapse in a hydrothermal system using hidden Markov models

    Science.gov (United States)

    Dawson, P.B.; Benitez, M.C.; Lowenstern, J. B.; Chouet, B.A.

    2012-01-01

    Beginning in July 2003 and lasting through September 2003, the Norris Geyser Basin in Yellowstone National Park exhibited an unusual increase in ground temperature and hydrothermal activity. Using hidden Markov model theory, we identify over five million high-frequency (>15Hz) seismic events observed at a temporary seismic station deployed in the basin in response to the increase in hydrothermal activity. The source of these seismic events is constrained to within ???100 m of the station, and produced ???3500-5500 events per hour with mean durations of ???0.35-0.45s. The seismic event rate, air temperature, hydrologic temperatures, and surficial water flow of the geyser basin exhibited a marked diurnal pattern that was closely associated with solar thermal radiance. We interpret the source of the seismicity to be due to the collapse of small steam bubbles in the hydrothermal system, with the rate of collapse being controlled by surficial temperatures and daytime evaporation rates. copyright 2012 by the American Geophysical Union.

  16. Acoustics advances study of sea floor hydrothermal flow

    Science.gov (United States)

    Rona, Peter A.; Jackson, Darrell R.; Bemis, Karen G.; Jones, Christopher D.; Mitsuzawa, Kyohiko; Palmer, David R.; Silver, Deborah

    Sub-sea floor hydrothermal convection systems discharge as plumes from point sources and as seepage from the ocean bottom. The plumes originate as clear, 150-400°C solutions that vent from mineralized chimneys; precipitate dissolved metals as particles to form black or white smokers as they turbulently mix with ambient seawater; and buoyantly rise hundreds of meters to a level of neutral density where they spread laterally. The seepage discharges from networks of fractures at the rock-water interface as clear, diffuse flow, with lower temperatures, metal contents, and buoyancy than the smokers. The diffuse flow may be entrained upward into plumes, or laterally by prevailing currents in discrete layers within tens of meters of the sea floor. The role of these flow regimes in dispersing heat, chemicals, and biological material into the ocean from sub-sea floor hydrothermal convection systems is being studied on a global scale.

  17. Identification and activity of acetate-assimilating bacteria in diffuse fluids venting from two deep-sea hydrothermal systems.

    Science.gov (United States)

    Winkel, Matthias; Pjevac, Petra; Kleiner, Manuel; Littmann, Sten; Meyerdierks, Anke; Amann, Rudolf; Mußmann, Marc

    2014-12-01

    Diffuse hydrothermal fluids often contain organic compounds such as hydrocarbons, lipids, and organic acids. Microorganisms consuming these compounds at hydrothermal sites are so far only known from cultivation-dependent studies. To identify potential heterotrophs without prior cultivation, we combined microbial community analysis with short-term incubations using (13)C-labeled acetate at two distinct hydrothermal systems. We followed cell growth and assimilation of (13)C into single cells by nanoSIMS combined with fluorescence in situ hybridization (FISH). In 55 °C-fluids from the Menez Gwen hydrothermal system/Mid-Atlantic Ridge, a novel epsilonproteobacterial group accounted for nearly all assimilation of acetate, representing the first aerobic acetate-consuming member of the Nautiliales. In contrast, Gammaproteobacteria dominated the (13) C-acetate assimilation in incubations of 37 °C-fluids from the back-arc hydrothermal system in the Manus Basin/Papua New Guinea. Here, 16S rRNA gene sequences were mostly related to mesophilic Marinobacter, reflecting the high content of seawater in these fluids. The rapid growth of microorganisms upon acetate addition suggests that acetate consumers in diffuse fluids are copiotrophic opportunists, which quickly exploit their energy sources, whenever available under the spatially and temporally highly fluctuating conditions. Our data provide first insights into the heterotrophic microbial community, catalyzing an under-investigated part of microbial carbon cycling at hydrothermal vents. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  18. Convective plasma stability consistent with MHD equilibrium in magnetic confinement systems with a decreasing field

    International Nuclear Information System (INIS)

    Tsventoukh, M. M.

    2010-01-01

    A study is made of the convective (interchange, or flute) plasma stability consistent with equilibrium in magnetic confinement systems with a magnetic field decreasing outward and large curvature of magnetic field lines. Algorithms are developed which calculate convective plasma stability from the Kruskal-Oberman kinetic criterion and in which the convective stability is iteratively consistent with MHD equilibrium for a given pressure and a given type of anisotropy in actual magnetic geometry. Vacuum and equilibrium convectively stable configurations in systems with a decreasing, highly curved magnetic field are calculated. It is shown that, in convectively stable equilibrium, the possibility of achieving high plasma pressures in the central region is restricted either by the expansion of the separatrix (when there are large regions of a weak magnetic field) or by the filamentation of the gradient plasma current (when there are small regions of a weak magnetic field, in which case the pressure drops mainly near the separatrix). It is found that, from the standpoint of equilibrium and of the onset of nonpotential ballooning modes, a kinetic description of convective stability yields better plasma confinement parameters in systems with a decreasing, highly curved magnetic field than a simpler MHD model and makes it possible to substantially improve the confinement parameters for a given type of anisotropy. For the Magnetor experimental compact device, the maximum central pressure consistent with equilibrium and stability is calculated to be as high as β ∼ 30%. It is shown that, for the anisotropy of the distribution function that is typical of a background ECR plasma, the limiting pressure gradient is about two times steeper than that for an isotropic plasma. From a practical point of view, the possibility is demonstrated of achieving better confinement parameters of a hot collisionless plasma in systems with a decreasing, highly curved magnetic field than those

  19. Temporal changes in fluid chemistry and energy profiles in the vulcano island hydrothermal system.

    Science.gov (United States)

    Rogers, Karyn L; Amend, Jan P; Gurrieri, Sergio

    2007-12-01

    In June 2003, the geochemical composition of geothermal fluids was determined at 9 sites in the Vulcano hydrothermal system, including sediment seeps, geothermal wells, and submarine vents. Compositional data were combined with standard state reaction properties to determine the overall Gibbs free energy (DeltaG(r) ) for 120 potential lithotrophic and heterotrophic reactions. Lithotrophic reactions in the H-O-N-S-C-Fe system were considered, and exergonic reactions yielded up to 120 kJ per mole of electrons transferred. The potential for heterotrophy was characterized by energy yields from the complete oxidation of 6 carboxylic acids- formic, acetic, propanoic, lactic, pyruvic, and succinic-with the following redox pairs: O(2)/H(2)O, SO(4) (2)/H(2)S, NO(3) ()/NH(4) (+), S(0)/H(2)S, and Fe(3)O(4)/Fe(2+). Heterotrophic reactions yielded 6-111 kJ/mol e(). Energy yields from both lithotrophic and heterotrophic reactions were highly dependent on the terminal electron acceptor (TEA); reactions with O(2) yielded the most energy, followed by those with NO(3) (), Fe(III), SO(4) (2), and S(0). When only reactions with complete TEA reduction were included, the exergonic lithotrophic reactions followed a similar electron tower. Spatial variability in DeltaG(r) was significant for iron redox reactions, owing largely to the wide range in Fe(2+) and H(+) concentrations. Energy yields were compared to those obtained for samples collected in June 2001. The temporal variations in geochemical composition and energy yields observed in the Vulcano hydrothermal system between 2001 and 2003 were moderate. The largest differences in DeltaG(r) over the 2 years were from iron redox reactions, due to temporal changes in the Fe(2+) and H(+) concentrations. The observed variations in fluid composition across the Vulcano hydrothermal system have the potential to influence not only microbial diversity but also the metabolic strategies of the resident microbial communities.

  20. Investigating Volcanic-Hydrothermal Systems in Dominica, Lesser Antilles: Temporal Changes in the Chemical Composition of Hydrothermal Fluids for Volcanic Monitoring Using Geothermometers

    Science.gov (United States)

    Onyeali, M. M. C.; Joseph, E. P.; Frey, H. M.

    2017-12-01

    Dominica has an abundance of volcanic activity, with nine potentially active volcanoes, many of which have highly active volcanic-hydrothermal systems. The waters are predominantly acid-sulphate in character (SO4=100-4200 mg/L, pH≤4), and likely formed because of dilution of acidic gases in near surface oxygenated groundwater. The waters are of primarily meteoric origin, but are likely affected by evaporation effects at/near the surface, with δ18O ranging from -1.75 to 10.67‰, and δD from -6.1 to 14.5‰. With updated water chemistry and isotopic data from five hydrothermal areas (Boiling Lake, Valley of Desolation, Sulphur Springs, Wotten Waven, Cold Soufriere) for the period 2014 to 2017, we will re-evaluate the characteristics of these systems, which were last reported in 2011. We will present updated reservoir temperatures using a variety of geothermometers and provide insight into water-rock interactions taking place in the reservoirs. Recent changes in chemistry of the waters have indicated that while the origin of the hydrothermal systems are still dominantly meteoric (δ18O = -3 to 8‰ and δD = -5 to 18‰), surface evaporation effects and variable amounts of mixing with shallow ground waters play an important role. Fumaroles appear to reflect a deeper source contribution as compared to thermal waters with differences in acidity, temperature, TDS, δ18O, and δD observed. The general composition of the waters for most of the hydrothermal systems studied indicate no significant changes, with the exception of the Boiling Lake, which experienced a draining event in November 2016 which lasted for 6 weeks. Decreases in temperature, pH, Na, K, and Cl were seen post draining, while SO4 remained relatively low (66 ppm), but showed a small increase. The chemistry of the Boiling Lake appears to show significant changes in response to changes in the groundwater system. Changes in the groundwater system at the lake observed during the 2004/2005 draining, which

  1. Evaluation of the Plant-Craig stochastic convection scheme in an ensemble forecasting system

    Science.gov (United States)

    Keane, R. J.; Plant, R. S.; Tennant, W. J.

    2015-12-01

    The Plant-Craig stochastic convection parameterization (version 2.0) is implemented in the Met Office Regional Ensemble Prediction System (MOGREPS-R) and is assessed in comparison with the standard convection scheme with a simple stochastic element only, from random parameter variation. A set of 34 ensemble forecasts, each with 24 members, is considered, over the month of July 2009. Deterministic and probabilistic measures of the precipitation forecasts are assessed. The Plant-Craig parameterization is found to improve probabilistic forecast measures, particularly the results for lower precipitation thresholds. The impact on deterministic forecasts at the grid scale is neutral, although the Plant-Craig scheme does deliver improvements when forecasts are made over larger areas. The improvements found are greater in conditions of relatively weak synoptic forcing, for which convective precipitation is likely to be less predictable.

  2. Relations of ammonium minerals at several hydrothermal systems in the western U.S.

    Science.gov (United States)

    Krohn, M.D.; Kendall, C.; Evans, J.R.; Fries, T.L.

    1993-01-01

    Ammonium bound to silicate and sulfate minerals has recently been located at several major hydrothermal systems in the western U.S. utilizing newly-discovered near-infrared spectral properties. Knowledge of the origin and mineralogic relations of ammonium minerals at known hydrothermal systems is critical for the proper interpretation of remote sensing data and for testing of possible links to mineralization. Submicroscopic analysis of ammonium minerals from two mercury- and gold-bearing hot-springs deposits at Ivanhoe, Nevada and McLaughlin, California shows that the ammonium feldspar, buddingtonite, occurs as fine-grained euhedral crystals coating larger sulfide and quartz crystals. Ammonium feldspar seems to precipitate relatively late in the crystallization sequence and shows evidence for replacement of NH4+ by K+ or other monovalent cations. Some buddingtonite is observed in close association with mercury, but not with gold. Ammonioalunite is found in a variety of isolated crystal forms at both deposits. Nitrogen isotopic values for ammonium-bearing minerals show a 14??? range in composition, precluding assignment of a specific provenance to the nitrogen. The correlations of nitrogen isotopic values with depth and ammonium content suggest some loss of nitrogen in the oxidizing supergene environment, possibly as a metastable mineral. The high ammonium content in these hydrothermal systems, the close association to mercury, and the small crystal size of the ammonium-bearing minerals all suggest that ammonium may be transported in a late-stage vapor phase or as an organic volatile. Such a process could lead to the formation of a non-carbonaceous organic aureole above a buried geothermal source. The discovery of a 10-km outcrop of ammonium minerals confirms that significant substitution of ammonium in minerals is possible over an extensive area and that remote sensing is a feasible means to detect such aureoles. ?? 1993.

  3. Development of Vertical Cable Seismic System for Hydrothermal Deposit Survey (2) - Feasibility Study

    Science.gov (United States)

    Asakawa, E.; Murakami, F.; Sekino, Y.; Okamoto, T.; Mikada, H.; Takekawa, J.; Shimura, T.

    2010-12-01

    In 2009, Ministry of Education, Culture, Sports, Science and Technology(MEXT) started the survey system development for Hydrothermal deposit. We proposed the Vertical Cable Seismic (VCS), the reflection seismic survey with vertical cable above seabottom. VCS has the following advantages for hydrothermal deposit survey. . (1) VCS is an effective high-resolution 3D seismic survey within limited area. (2) It achieves high-resolution image because the sensors are closely located to the target. (3) It avoids the coupling problems between sensor and seabottom that cause serious damage of seismic data quality. (4) Various types of marine source are applicable with VCS such as sea-surface source (air gun, water gun etc.) , deep-towed or ocean bottom sources. (5) Autonomous recording system. Our first experiment of 2D/3D VCS surveys has been carried out in Lake Biwa, JAPAN. in November 2009. The 2D VCS data processing follows the walk-away VSP, including wave field separation and depth migration. The result gives clearer image than the conventional surface seismic. Prestack depth migration is applied to 3D data to obtain good quality 3D depth volume. Uncertainty of the source/receiver poisons in water causes the serious problem of the imaging. We used several transducer/transponder to estimate these positions. The VCS seismic records themselves can also provide sensor position using the first break of each trace and we calibrate the positions. We are currently developing the autonomous recording VCS system and planning the trial experiment in actual ocean to establish the way of deployment/recovery and the examine the position through the current flow in November, 2010. The second VCS survey will planned over the actual hydrothermal deposit with deep-towed source in February, 2011.

  4. Multiple objective optimization of hydro-thermal systems using Ritz's method

    Directory of Open Access Journals (Sweden)

    L. Bayón Arnáu

    2000-01-01

    Full Text Available This paper examines the applicability of the Ritz method to multi-objective optimization of hydro-thermal systems. The algorithm proposed is aimed to minimize an objective functional that incorporates the cost of energy losses, the conventional fuel cost and the production of atmospheric emissions such as NOx and SO2 caused by the operation of fossil-fueled thermal generation. The formulation includes a general layout of hydro-plants that may form multi-chains of reservoir network.

  5. Automatic generation control of TCPS based hydrothermal system under open market scenario: A fuzzy logic approach

    Energy Technology Data Exchange (ETDEWEB)

    Rao, C. Srinivasa [EEE Department, G. Pulla Reddy Engineering College, Kurnool, Andhra Pradesh (India); Nagaraju, S. Siva [EEE Department, J.N.T.U College of Engg., Kakinada, Andhra Pradesh (India); Raju, P. Sangameswara [EEE Department, S.V. University, Tirupati, Andhra Pradesh (India)

    2009-09-15

    This paper presents the analysis of automatic generation control of a two-area interconnected thyristor controlled phase shifter based hydrothermal system in the continuous mode using fuzzy logic controller under open market scenario. Open transmission access and the evolving of more socialized companies for generation, transmission and distribution affects the formulation of AGC problem. So the traditional AGC two-area system is modified to take into account the effect of bilateral contracts on the dynamics. It is possible to stabilize the system frequency and tie-power oscillations by controlling the phase angle of TCPS which is expected to provide a new ancillary service for the future power systems. A control strategy using TCPS is proposed to provide active control of system frequency. Further dynamic responses for small perturbation considering fuzzy logic controller and PI controller (dual mode controller) have been observed and the superior performance of fuzzy logic controller has been reported analytically and also through simulation. (author)

  6. Insight from Genomics on Biogeochemical Cycles in a Shallow-Sea Hydrothermal System

    Science.gov (United States)

    Lu, G. S.; Amend, J.

    2015-12-01

    Shallow-sea hydrothermal ecosystems are dynamic, high-energy systems influenced by sunlight and geothermal activity. They provide accessible opportunities for investigating thermophilic microbial biogeochemical cycles. In this study, we report biogeochemical data from a shallow-sea hydrothermal system offshore Paleochori Bay, Milos, Greece, which is characterized by a central vent covered by white microbial mats with hydrothermally influenced sediments extending into nearby sea grass area. Geochemical analysis and deep sequencing provide high-resolution information on the geochemical patterns, microbial diversity and metabolic potential in a two-meter transect. The venting fluid is elevated in temperature (~70oC), low in pH (~4), and enriched in reduced species. The geochemical pattern shows that the profile is affected by not only seawater dilution but also microbial regulation. The microbial community in the deepest section of vent core (10-12 cm) is largely dominated by thermophilic archaea, including a methanogen and a recently described Crenarcheon. Mid-core (6-8 cm), the microbial community in the venting area switches to the hydrogen utilizer Aquificae. Near the sediment-water interface, anaerobic Firmicutes and Actinobacteria dominate, both of which are commonly associated with subsurface and hydrothermal sites. All other samples are dominated by diverse Proteobacteria. The sulfate profile is strongly correlated with the population size of delta- and episilon-proteobactia. The dramatic decrease in concentrations of As and Mn in pore fluids as a function of distance from the vent suggests that in addition to seawater dilution, microorganisms are likely transforming these and other ions through a combination of detoxification and catabolism. In addition, high concentrations of dissolved Fe are only measurable in the shallow sea grass area, suggesting that iron-transforming microorganisms are controlling Fe mobility, and promoting biomineralization. Taken

  7. The eastern Tibetan Plateau geothermal belt, western China: Geology, geophysics, genesis, and hydrothermal system

    Science.gov (United States)

    Tang, Xianchun; Zhang, Jian; Pang, Zhonghe; Hu, Shengbiao; Tian, Jiao; Bao, Shujing

    2017-10-01

    The eastern Tibetan Plateau geothermal belt (ETGB), which is located in 98-102°E, 28-32°N, belongs to the eastern part of the Mediterranean-Himalayan geothermal belt. Recently, about 248 natural hot springs have been found in the ETGB. > 60% of these springs have temperatures of > 40 °C, and 11 springs have temperature above the local water boiling point. Using the helium isotopic data, gravity, magnetic and seismic data, we analyzed the thermal structure and the relationship between hydrothermal activity and geothermal dynamics of the ETGB. Results show that: (1) the 248 springs can be divided into three geothermal fields: Kangding-Luhuo geothermal field (KGF), Litang-Ganzi geothermal field (LGF) and Batang-Xiangcheng geothermal field (BGF). The BGF and LGF have hot crust and warm mantle, and are characterized by the higher heat flux (66.26 mW/m2), and higher ratios of crust-derived heat flux to total flux (47.46-60.62%). The KGF has cool crust and hot mantle, and is characterized by the higher heat flux and lower Qc/Qm; (2) there is a relatively 4-6 m higher gravimetric geoid anomaly dome which is corresponding with the ETGB. And in hydrothermal activity areas of the BGF and LGF, there is a northwest - southeast-trending tensile stress area and the upper-middle crust uplift area; (3) an abnormal layer exists in the middle-lower crust at a depth of 13-30 km beneath the ETGB, and this layer is 8-10 km thick and is characterized by lower velocity (Vp 2.5), high conductivity ( 10 Ω·m) and high temperature (850-1000 °C). Finally, based on the heat source and geological and geophysical background, we propose Kangding-type and Batang-type hydrothermal system models in the ETGB.

  8. Interaction between daily load demand curve and management of hydro-thermal generation system

    International Nuclear Information System (INIS)

    Granelli, G.; Montagna, M.; Pasini, G.; Innorta, M.; Marannino, P.

    1993-01-01

    The influence that the behaviour of the daily load demand curve has on the management of a hydro-thermal generation system is considered. The aim of this paper is to show the improvements that can be achieved by suitable load management techniques capable of flattening the load demand curve. The analysis is carried out by using a hydro-thermal scheduling program and a thermal unit dynamic dispatch procedure. The possibility of properly re-committing the available thermal units is also taken into account. The economical and technical convenience of shutting down less economical thermal units operating near the lower generations limits is verified. Finally, some considerations are made about the possible use of the thermal generation incremental costs as a tool for planning the end users' kWh prices, even in the short term. The results refer to a system with characteristics similar to those of the Italian one. In determining the daily load demand curves, the characteristics of load demand in Italy as well as in other European countries are taken into account

  9. Intraseasonal variability of organized convective systems in the Central Andes: Relationship to Regional Dynamical Features

    Science.gov (United States)

    Mohr, K. I.; Slayback, D. A.; Nicholls, S.; Yager, K.

    2013-12-01

    The Andes extend from the west coast of Colombia (10N) to the southern tip of Chile (53S). In southern Peru and Bolivia, the Central Andes is split into separate eastern and western cordilleras, with a high plateau (≥ 3000 m), the Altiplano, between them. Because 90% of the Earth's tropical mountain glaciers are located in the Central Andes, our study focuses on this region, defining its zonal extent as 7S-21S and the meridional extent as the terrain 1000 m and greater. Although intense convection occurs during the wet season in the Altiplano, it is not included in the lists of regions with frequent or the most intense convection. The scarcity of in-situ observations with sufficient density and temporal resolution to resolve individual storms or even mesoscale-organized cloud systems and documented biases in microwave-based rainfall products in poorly gauged mountainous regions have impeded the development of an extensive literature on convection and convective systems in this region. With the tropical glaciers receding at unprecedented rates, leaving seasonal precipitation as an increasingly important input to the water balance in alpine valley ecosystems and streams, understanding the nature and characteristics of the seasonal precipitation becomes increasingly important for the rural economies in this region. Previous work in analyzing precipitation in the Central Andes has emphasized interannual variability with respect to ENSO, this is the first study to focus on shorter scale variability with respect to organized convection. The present study took advantage of the University of Utah's Precipitation Features database compiled from 14 years of TRMM observations (1998-2012), supplemented by field observations of rainfall and streamflow, historical gauge data, and long-term WRF-simulations, to analyze the intraseasonal variability of precipitating systems and their relationship regional dynamical features such as the Bolivian High. Through time series and

  10. Visualization of Natural Convection Heat Transfer on a Single Sphere using the Electroplating System

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Young; Chung, Bum Jin [Kyunghee University, Yongin (Korea, Republic of)

    2016-05-15

    The natural convective flows on outer sphere rise along surface. At top of sphere, the flows are lifted-up plume shape. For laminar flows, the local heat transfer shows maximum at the bottom of sphere and a monotonic decreases as flows approached to the top. The laminar natural convection heat transfer on a single sphere has been studied experimentally and numerically by several researchers. However, relatively less study has been performed for turbulent flows as it requires large facilities to achieve high Rayleigh numbers. The flows, which occur transition, is hard to experiment because of unstable. This study tried measurement of heat transfer and visualization external natural convection on a single sphere. The basic idea is that the plating patterns of copper on the sphere in mass transfer system will reveal the amount of heat transfer according to angular distance from the bottom. This study simulated natural convection on a single sphere and performed a mass transfer experiment using heat and mass transfer analogy concept. For visualization experiment, streak form plating pattern was observed. In this case, it seems that turbulence sets on the top of sphere and increases local heat transfer.

  11. Evaluation of a Mesoscale Convective System in Variable-Resolution CESM

    Science.gov (United States)

    Payne, A. E.; Jablonowski, C.

    2017-12-01

    Warm season precipitation over the Southern Great Plains (SGP) follows a well observed diurnal pattern of variability, peaking at night-time, due to the eastward propagation of mesoscale convection systems that develop over the eastern slopes of the Rockies in the late afternoon. While most climate models are unable to adequately capture the organization of convection and characteristic pattern of precipitation over this region, models with high enough resolution to explicitly resolve convection show improvement. However, high resolution simulations are computationally expensive and, in the case of regional climate models, are subject to boundary conditions. Newly developed variable resolution global climate models strike a balance between the benefits of high-resolution regional climate models and the large-scale dynamics of global climate models and low computational cost. Recently developed parameterizations that are insensitive to the model grid scale provide a way to improve model performance. Here, we present an evaluation of the newly available Cloud Layers Unified by Binormals (CLUBB) parameterization scheme in a suite of variable-resolution CESM simulations with resolutions ranging from 110 km to 7 km within a regionally refined region centered over the SGP Atmospheric Radiation Measurement (ARM) site. Simulations utilize the hindcast approach developed by the Department of Energy's Cloud-Associated Parameterizations Testbed (CAPT) for the assessment of climate models. We limit our evaluation to a single mesoscale convective system that passed over the region on May 24, 2008. The effects of grid-resolution on the timing and intensity of precipitation, as well as, on the transition from shallow to deep convection are assessed against ground-based observations from the SGP ARM site, satellite observations and ERA-Interim reanalysis.

  12. A study of the 21 March 2012 tornadic quasi linear convective system in Catalonia

    Science.gov (United States)

    Bech, Joan; Arús, Joan; Castán, Salvador; Pineda, Nicolau; Rigo, Tomeu; Montanyà, Joan; van der Velde, Oscar

    2015-05-01

    This study presents a description of a quasi linear convective system that took place in Catalonia (NE Spain) on 21 March 2012 producing heavy rainfall, moderate lightning activity and a weak tornado in the village of Ivars d'Urgell around 19 UTC after local sunset. A post-event survey indicated EF0 and EF1 damage in houses of the village - roofs and ceilings, broken windows, fences and walls and trees knocked down - along a track approximately 4 km long and about 20 m wide. Doppler radar observations show that the parent thunderstorm that spawned the tornado was one of a series that developed along a convective line that moved from S to N, initiating convective activity in terms of precipitation and lightning in the Mediterranean Sea and moving inland in S Catalonia (Tarragona and Salou coastal areas, producing local flash floods). Convective activity remained several hours with series of thunderstorms developing along the same paths. The synoptic situation was dominated by a high pressure ridge extending from northern Africa to central Europe, with a closed maximum sea level pressure area around 1036 hPa over northern France, southern Germany and Austria. On the other hand a relative low pressure area seen on 850 hPa and upper levels was present over the Iberian Peninsula, favouring a southern maritime flow from the Mediterranean between the forward part of the low pressure area and the high pressure system which blocked the advance of the low to the east. In the study we examine both the synoptic environment and storm scale observations with Doppler radar and total lightning data (cloud to ground and intracloud flashes) that lead to this cool-season severe convective event which is remarkable given the fact that, unlike in this case, most reported tornadoes in the region occur during the warm season (with peaks in August and September) and during daylight hours (6 to 18 UTC).

  13. Isotope hydrology of some hydrothermal systems of the Kurilo-Kamchatskay volcanic region

    International Nuclear Information System (INIS)

    Esikov, A.D.

    1990-01-01

    The hydrogen and oxygen isotope composition of underground and surface (thermal and cold) waters, as well as local precipitation waters from the geothermal fields of the Uzon caldera, the Mutnovsky volcano (Kamchatka), and the Baransky volcano (island of Iturup) have been analysed. As has been demonstrated, hydrothermal solutions were formed due to hypogene circulation of water originating from local precipitation. Observed variations in the isotope composition of the water are easily explained by underground boiling of hydrothermal solutions and their exchange with bedrock, and also by the processes of non-steady evaporation of water under differing surface conditions and the widely-spread mutual intermixing of waters of different origin. Data on the isotope composition of 50 samples from the region studied are to be found in the paper. The method of constructing diagrams in coordinates of δD vs δ 18 O is discussed in detail, reflecting a single-step separation of the thermal fluid. Data obtained during the analysis of the thermal fields estimates the processes forming the isotope composition of the world's geothermal sub-aerial systems as being unique. (author)

  14. VALORAGUA: A model for the optimal operating strategy of mixed hydrothermal generating systems

    International Nuclear Information System (INIS)

    1992-01-01

    To provide assistance to its developing Member States in carrying out integrated power system expansion analysis, the International Atomic Energy Agency (IAEA) has developed the computer model called WASP (Wien Automatic System Planning Package). The WASP model has proven to be very useful for this purpose and is accepted worldwide as a sound tool for electricity planning. Notwithstanding its many advantages, certain shortcomings of the methodology have been noticed, in particular with regard to representation of hydroelectric power plants. In order to overcome these shortcomings, the IAEA decided to acquire the computer model called VALORAGUA, developed by the Electricidade de Portugal (EDP), for optimizing the operating strategy of a mixed hydro-thermal power system. This program, when used together with WASP, would allow economic optimization of hydro-thermal power systems with a large hydro component. The objective of the present document is to assist in the use of the VALORAGUA model and its auxiliary codes, as well as to clarify the interconnection between VALORAGUA and the WASP-III model. This report is organized into five main chapters. The first chapter serves as an introduction to all remaining chapters. Chapter 2 defines the input data needed for every component of the electric power system. Chapter 3 presents the output variables of the model within the standard output tables that can be produced by VALORAGUA. Chapter 4 describes in detail all the input data needed by each program. It also includes the list of computer input data corresponding to the example described in Chapter 5, which is used to illustrate the execution of the VALORAGUA modules. Description of how to prepare the hydro data for the WASP-III model from the results obtained with the VALORAGUA model is given in Appendix A. Some auxiliary programs of the VALORAGUA model system, developed by EDP to help the user with the input data preparation, are described in Appendix B. Refs, figs and

  15. An Automated System to Quantify Convectively induced Aircraft encounters with Turbulence over Europe and North Atlantic

    Science.gov (United States)

    Meneguz, Elena; Turp, Debi; Wells, Helen

    2015-04-01

    It is well known that encounters with moderate or severe turbulence can lead to passenger injuries and incur high costs for airlines from compensation and litigation. As one of two World Area Forecast Centres (WAFCs), the Met Office has responsibility for forecasting en-route weather hazards worldwide for aviation above a height of 10,000 ft. Observations from commercial aircraft provide a basis for gaining a better understanding of turbulence and for improving turbulence forecasts through verification. However there is currently a lack of information regarding the possible cause of the observed turbulence, or whether the turbulence occurred within cloud. Such information would be invaluable for the development of forecasting techniques for particular types of turbulence and for forecast verification. Of all the possible sources of turbulence, convective activity is believed to be a major cause of turbulence. Its relative importance over the Europe and North Atlantic area has not been yet quantified in a systematic way: in this study, a new approach is developed to automate identification of turbulent encounters in the proximity of convective clouds. Observations of convection are provided from two independent sources: a surface based lightning network and satellite imagery. Lightning observations are taken from the Met Office Arrival Time Detections network (ATDnet). ATDnet has been designed to identify cloud-to-ground flashes over Europe but also detects (a smaller fraction of) strikes over the North Atlantic. Meteosat Second Generation (MSG) satellite products are used to identify convective clouds by applying a brightness temperature filtering technique. The morphological features of cold cloud tops are also investigated. The system is run for all in situ turbulence reports received from airlines for a total of 12 months during summer 2013 and 2014 for the domain of interest. Results of this preliminary short term climatological study show significant intra

  16. Radar Observations of Convective Systems from a High-Altitude Aircraft

    Science.gov (United States)

    Heymsfield, G.; Geerts, B.; Tian, L.

    1999-01-01

    Reflectivity data collected by the precipitation radar on board the tropical Rainfall Measuring Mission (TRMM) satellite, orbiting at 350 km altitude, are compared to reflectivity data collected nearly simultaneously by a doppler radar aboard the NASA ER-2 flying at 19-20 km altitude, i.e. above even the deepest convection. The TRMM precipitation radar is a scanning device with a ground swath width of 215 km, and has a resolution of about a4.4 km in the horizontal and 250 m in the vertical (125 m in the core swath 48 km wide). The TRMM radar has a wavelength of 217 cm (13.8 GHz) and the Nadir mirror echo below the surface is used to correct reflectivity for loss by attenuation. The ER-2 Doppler radar (EDOP) has two antennas, one pointing to the nadir, 34 degrees forward. The forward pointing beam receives both the normal and the cross-polarized echos, so the linear polarization ratio field can be monitored. EDOP has a wavelength of 3.12 cm (9.6 GHz), a vertical resolution of 37.5 m and a horizontal along-track resolution of about 100 m. The 2-D along track airflow field can be synthesized from the radial velocities of both beams, if a reflectivity-based hydrometer fall speed relation can be assumed. It is primarily the superb vertical resolution that distinguishes EDOP from other ground-based or airborne radars. Two experiments were conducted during 1998 into validate TRMM reflectivity data over convection and convectively-generated stratiform precipitation regions. The Teflun-A (TEXAS-Florida Underflight) experiment, was conducted in April and May and focused on mesoscale convective systems mainly in southeast Texas. TEFLUN-B was conducted in August-September in central Florida, in coordination with CAMEX-3 (Convection and Moisture Experiment). The latter was focused on hurricanes, especially during landfall, whereas TEFLUN-B concentrated on central; Florida convection, which is largely driven and organized by surface heating and ensuing sea breeze circulations

  17. Automatic generation control of an interconnected hydrothermal power system considering superconducting magnetic energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, Rajesh Joseph; Das, D.; Patra, Amit [Department of Electrical Engineering, Indian Institute of Technology, Kharagpur 721 302 (India)

    2007-10-15

    This paper presents the analysis of automatic generation control (AGC) of an interconnected hydrothermal power system in the presence of generation rate constraints (GRCs). The improvement of AGC with the addition of a small capacity superconducting magnetic energy storage (SMES) unit in either, as well as in both the areas are studied. Time domain simulations are used to study the performance of the power system and control logic. The optimal values of the integral gain settings are obtained using integral squared error (ISE) technique by minimising a quadratic performance index. Suitable method for controlling the SMES unit is described. Analysis reveals that SMES unit fitted in either of the areas is as effective as SMES units fitted in both the areas and improves the dynamic performances to a considerable extent following a load disturbance in either of the areas. (author)

  18. Effect of surface radiation on natural convection in an asymmetrically heated channel-chimney system

    Science.gov (United States)

    Nasri, Zied; Derouich, Youssef; Laatar, Ali Hatem; Balti, Jalloul

    2018-05-01

    In this paper, a more realistic numerical approach that takes into account the effect of surface radiation on the laminar air flow induced by natural convection in a channel-chimney system asymmetrically heated at uniform heat flux is used. The aim is to enrich the results given in Nasri et al. (Int J Therm Sci 90:122-134, 2015) by varying all the geometric parameters of the system and by taking into account the effect of surface radiation on the flows. The numerical results are first validated against experimental and numerical data available in the literature. The computations have allowed the determination of optimal configurations that maximize the mass flow rate and the convective heat transfer and minimize the heated wall temperatures. The analysis of the temperature fields with the streamlines and the pressure fields has helped to explain the effects of surface radiation and of the different thermo-geometrical parameters on the system performances to improve the mass flow rate and the heat transfer with respect to the simple channel. It is shown that the thermal performance of the channel-chimney system in terms of lower heated wall temperatures is little affected by the surface radiation. At the end, simple correlation equations have been proposed for quickly and easily predict the optimal configurations as well as the corresponding enhancement rates of the induced mass flow rate and the convective heat transfer.

  19. Effects of chemical alteration on fracture mechanical properties in hydrothermal systems

    Science.gov (United States)

    Callahan, O. A.; Eichhubl, P.; Olson, J. E.

    2015-12-01

    Fault and fracture networks often control the distribution of fluids and heat in hydrothermal and epithermal systems, and in related geothermal and mineral resources. Additional chemical influences on conduit evolution are well documented, with dissolution and precipitation of mineral species potentially changing the permeability of fault-facture networks. Less well understood are the impacts of chemical alteration on the mechanical properties governing fracture growth and fracture network geometry. We use double-torsion (DT) load relaxation tests under ambient air conditions to measure the mode-I fracture toughness (KIC) and subcritical fracture growth index (SCI) of variably altered rock samples obtained from outcrop in Dixie Valley, NV. Samples from southern Dixie Valley include 1) weakly altered granite, characterized by minor sericite in plagioclase, albitization and vacuolization of feldspars, and incomplete replacement of biotite with chlorite, and 2) granite from an area of locally intense propylitic alteration with chlorite-calcite-hematite-epidote assemblages. We also evaluated samples of completely silicified gabbro obtained from the Dixie Comstock epithermal gold deposit. In the weakly altered granite KIC and SCI are 1.3 ±0.2 MPam1/2 (n=8) and 59 ±25 (n=29), respectively. In the propylitic assemblage KIC is reduced to 0.6 ±0.1 MPam1/2 (n=11), and the SCI increased to 75 ±36 (n = 33). In both cases, the altered materials have lower fracture toughness and higher SCI than is reported for common geomechanical standards such as Westerly Granite (KIC ~1.7 MPam1/2; SCI ~48). Preliminary analysis of the silicified gabbro shows a significant increase in fracture toughness, 3.6 ±0.4 MPam1/2 (n=2), and SCI, 102 ±45 (n=19), compared to published values for gabbro (2.9 MPam1/2 and SCI = 32). These results suggest that mineralogical and textural changes associated with different alteration assemblages may result in spatially variable rates of fracture

  20. Cu-As Decoupling in Hydrothermal Systems: A Link Between Pyrite Chemistry and Fluid Composition

    Science.gov (United States)

    Reich, M.; Tardani, D.; Deditius, A.; Chryssoulis, S.; Wrage, J.; Sanchez-Alfaro, P.; Andrea, H.; Cinthia, J.

    2016-12-01

    Chemical zonations in pyrite have been recognized in most hydrothermal ore deposit types, showing in some cases marked oscillatory alternation of metals and metalloids in pyrite growth zones (e.g., of Cu-rich, As-(Au)-depleted zones and As-(Au)-rich, Cu-depleted zones). This decoupled geochemical behavior of Cu and As has been interpreted as a result of chemical changes in ore-forming fluids, although direct evidence connecting fluctuations in hydrothermal fluid composition with metal partitioning into pyrite growth zones is still lacking. Here we report a comprehensive trace element database of pyrite from an active hydrothermal system, the Tolhuaca Geothermal System (TGS) in southern Chile. We combined high-spatial resolution and X-ray mapping capabilities of electron microprobe analysis (EMPA) with low detection limits and depth-profiling capabilities of secondary-ion mass spectrometry (SIMS) in a suite of pyrite samples retrieved from a 1 km drill hole that crosses the argillic and propylitic alteration zones of the geothermal system. We show that the concentrations of precious metals (e.g., Au, Ag), metalloids (e.g., As, Sb, Se, Te), and base and heavy metals (e.g., Cu, Co, Ni, Pb) in pyrite at the TGS are significant. Among the elements analyzed, arsenic, Cu and Co are the most abundant with concentrations that vary from sub-ppm levels to a few wt. %. Pyrites from the deeper propylitic zone do not show significant zonation and high Cu-(Co)-As concentrations correlate with each other. In contrast, well-developed zonations were detected in pyrite from the shallow argillic alteration zone, where Cu(Co)-rich, As-depleted cores alternate with Cu(Co)-depleted, As-rich rims. These microanalytical data were contrasted with chemical data of fluid inclusion in quartz veins (high Cu/Na and low As/Na) and borehole fluids (low Cu/Na and high As/Na) reported at the TGS, showing a clear correspondence between Cu and As concentrations in pyrite-forming fluids and chemical

  1. Evolution of the Bucium Rodu and Frasin magmatic-hydrothermal system, Metaliferi Mountains, Romania

    Science.gov (United States)

    Iatan, Elena Luisa; Berbeleac, Ion; Visan, Madalina; Minut, Adrian; Nadasan, Laurentiu

    2013-04-01

    The Miocene Bucium Rodu and Frasin maar-diatreme structures and related Au-Ag epithermal low sulfidation with passing to mesothermal mineralizations are located in the Bucium-Rosia Montana-Baia de Aries metallogenetic district, within so called the "Golden Quatrilaterum", in the northeastern part of the Metaliferi Mountains. These structures are situated at about 5 km southeast from Rosia Montana, the largest European Au-Ag deposit. The total reserves for Bucium Rodu-Frasin are estimated at 43.3 Mt with average contents of 1.3 g/t Au and 3 g/t Ag. The Miocene geological evolution of Bucium Rodu and Frasin magmatic-hydrothermal system took place in closely relationships with tectonic, magmatic and metallogenetic activity from Bucium-Rosia Montana-Baia de Aries district in general, and adjacent areas, in special. The hydrothermal alteration is pervasive; adularia followed by phyllic, carbonatization and silicification alterations, usually show a close relationship with the mineralizations. Propylitic alteration occurs dominantly towards the depth; argillic alteration shows a local character. The mineralization occurs in veins, breccias, stockworks and disseminations and is hosted within two volcanic structures emplaced into a sequence of Cretaceous sediments in closely genetically relations with the Miocene phreatomagmatic fracturing and brecciation events. Within Rodu maar-diatreme structure the mineralizations follow especially the contact between the diatreme and Cretaceous flysch. The vein sets with low, moderately and near vertical dippings, cover 400x400m with N-S trend. The most important mineralization style is represented by veins, accompanied by hydrothermal breccias and disseminations. The veins spatial distribution relives as "en echelon" tension veins. They carry gold, minor base metal sulphides (pyrite, chalcopyrite, sphalerite, galena, tetrahedrite, arsenopyrite). Gangue is represented by carbonates (calcite, dolomite, ankerite, siderite, rhodochrosite

  2. The Role of Siliceous Hydrothermal Breccias in the Genesis of Volcanic Massive Sulphide Deposits - Ancient and Recent Systems

    Science.gov (United States)

    Costa, I. A.; Barriga, F. J.; Fouquet, Y.

    2014-12-01

    Siliceous hydrothermal breccias were sampled in two Mid-Atlantic Ridge active sites: Lucky Strike and Menez Gwen. These hydrothermal fields are located in the border of the Azorean plateau, southwest of the Azores islands where the alteration processes affecting basaltic rocks are prominent (Costa et al., 2003). The hydrothermal breccias are genetically related with the circulation of low temperature hydrothermal fluids in diffuse vents. The groundmass of these breccias precipitates from the fluid and consolidates the clastic fragments mostly composed of basalt. The main sources are the surrounding volcanic hills. Breccias are found near hydrothermal vents and may play an important role in the protection of subseafloor hydrothermal deposits forming an impermeable cap due to the high content in siliceous material. The amorphous silica tends to precipitate when the fluid is conductively cooled as proposed by Fouquet et al. (1998) after Fournier (1983). The process evolves gradually from an initial stage where we have just the fragments and circulating seawater. The ascending hydrothermal fluid mixes with seawater, which favours the precipitation of the sulphide components. Sealing of the initially loose fragments begins, the temperature rises below this crust, and the processes of mixing fluid circulation and conductive cooling are simultaneous. At this stage the fluid becomes oversaturated with respect to amorphous silica. This form of silica can precipitate in the open spaces of the porous sulphides and seal the system. Normally this can happen at low temperatures. At this stage the hydrothermal breccia is formed creating a progressively less permeable, eventually impermeable cap rock at the surface. Once the fluid is trapped under this impermeable layer, conductive cooling is enhanced and mixing with seawater is restricted, making the precipitation of amorphous silica more efficient. Since the first discovery and description of recent mineralized submarine

  3. Numerical analysis of a natural convection cooling system for radioactive canisters storage

    Energy Technology Data Exchange (ETDEWEB)

    Tsal, R.J.; Anwar, S.; Mercada, M.G. [Fluor Daniel Inc., Irvine, CA (United States)

    1995-02-01

    This paper describes the use of numerical analysis for studying natural convection cooling systems for long term storage of heat producing radioactive materials, including special nuclear materials and nuclear waste. The paper explains the major design philosophy, and shares the experiences of numerical modeling. The strategy of storing radioactive material is to immobilize nuclear high-level waste by a vitrification process, convertion it into borosilicate glass, and cast the glass into stainless steel canisters. These canisters are seal welded, decontaminated, inspected, and temporarily stored in an underground vault until they can be sent to a geologic repository for permanent storage. These canisters generate heat by nuclear decay of radioactive isotopes. The function of the storage facility ventilation system is to ensure that the glass centerline temperature does not exceed the glass transition temperature during storage and the vault concrete temperatures remain within the specified limits. A natural convection cooling system was proposed to meet these functions. The effectiveness of a natural convection cooling system is dependent on two major factors that affect air movement through the vault for cooling the canisters: (1) thermal buoyancy forces inside the vault which create a stack effect, and (2) external wind forces, that may assist or oppose airflow through the vault. Several numerical computer models were developed to analyze the thermal and hydraulic regimes in the storage vault. The Site Model is used to simulate the airflow around the building and to analyze different air inlet/outlet devices. The Airflow Model simulates the natural convection, thermal regime, and hydraulic resistance in the vault. The Vault Model, internal vault temperature stratification; and, finally, the Hot Area Model is used for modeling concrete temperatures within the vault.

  4. Breakdown of hot-spot model in determining convective amplification in large homogeneous systems

    International Nuclear Information System (INIS)

    Mounaix, Philippe; Divol, Laurent

    2004-01-01

    Convective amplification in large homogeneous systems is studied, both analytically and numerically, in the case of a linear diffraction-free stochastic amplifier. Overall amplification does not result from successive amplifications in small scale high intensity hot spots, but from a single amplification in a delocalized mode of the driver field spreading over the whole interaction length. For this model, the hot-spot approach is found to systematically underestimate the gain factor by more than 50%

  5. Burnout in boiling heat transfer. Part II: subcooled and low quality forced-convection systems

    International Nuclear Information System (INIS)

    Bergles, A.E.

    1977-01-01

    Recent experimental and analytical developments regrading burnout in subcooled and low quality forced-convection systems are reviewed. Much data have been accumulated which clarify the parametric trends and lead to new design correlations for water and a variety of other coolants in both simple and complex geometries. A number of critical experiments and models have been developed to attempt to clarify the burnout mechanism(s) in simpler geometries and power transients

  6. Burnout in boiling heat transfer. Part III. High-quality forced-convection systems

    International Nuclear Information System (INIS)

    Bergles, A.E.

    1979-01-01

    This is the final part of a review of burnout during boiling heat transfer. The status of burnout in high-quality forced-convection systems is reviewed, and recent developments are summarized in detail. A general guide to the considerable literature is given. Parametric effects and correlations for water in circular and noncircular ducts are presented. Other topics discussed include transients, steam-generator applications, correlations for other fluids, fouling, and augmentation

  7. On a Five-Dimensional Chaotic System Arising from Double-Diffusive Convection in a Fluid Layer

    Directory of Open Access Journals (Sweden)

    R. Idris

    2013-01-01

    Full Text Available A chaotic system arising from double-diffusive convection in a fluid layer is investigated in this paper based on the theory of dynamical systems. A five-dimensional model of chaotic system is obtained using the Galerkin truncated approximation. The results showed that the transition from steady convection to chaos via a Hopf bifurcation produced a limit cycle which may be associated with a homoclinic explosion at a slightly subcritical value of the Rayleigh number.

  8. Geochemical constraints on sources of metabolic energy for chemolithoautotrophy in ultramafic-hosted deep-sea hydrothermal systems.

    Science.gov (United States)

    McCollom, Thomas M

    2007-12-01

    Numerical models are employed to investigate sources of chemical energy for autotrophic microbial metabolism that develop during mixing of oxidized seawater with strongly reduced fluids discharged from ultramafic-hosted hydrothermal systems on the seafloor. Hydrothermal fluids in these systems are highly enriched in H(2) and CH(4) as a result of alteration of ultramafic rocks (serpentinization) in the subsurface. Based on the availability of chemical energy sources, inferences are made about the likely metabolic diversity, relative abundance, and spatial distribution of microorganisms within ultramafic-hosted systems. Metabolic reactions involving H(2) and CH(4), particularly hydrogen oxidation, methanotrophy, sulfate reduction, and methanogenesis, represent the predominant sources of chemical energy during fluid mixing. Owing to chemical gradients that develop from fluid mixing, aerobic metabolisms are likely to predominate in low-temperature environments (energy per kilogram of hydrothermal fluid, while anaerobic metabolic reactions can supply about 1 kJ, which is sufficient to support a maximum of approximately 120 mg (dry weight) of primary biomass production by aerobic organisms and approximately 20-30 mg biomass by anaerobes. The results indicate that ultramafic-hosted systems are capable of supplying about twice as much chemical energy as analogous deep-sea hydrothermal systems hosted in basaltic rocks.

  9. Multiple objective optimization of hydro-thermal systems using Ritz's method

    Directory of Open Access Journals (Sweden)

    Arnáu L. Bayón

    1999-01-01

    Full Text Available This paper examines the applicability of the Ritz method to multi-objective optimization of hydro-thermal systems. The algorithm proposed is aimed to minimize an objective functional that incorporates the cost of energy losses, the conventional fuel cost and the production of atmospheric emissions such as NO x and SO 2 caused by the operation of fossil-fueled thermal generation. The formulation includes a general layout of hydro-plants that may form multi-chains of reservoir network. Time-delays are included and the electric network is considered by using the active power balance equation. The volume of water discharge for each hydro-plant is a given constant amount from the optimization interval. The generic minimization algorithm, which is not difficult to construct on the basis of the Ritz method, has certain advantages in comparison with the conventional methods.

  10. Numerical modeling of a downwind-developing mesoscale convective system over the Masurian Lake District

    Directory of Open Access Journals (Sweden)

    Wójcik Damian K.

    2017-01-01

    Full Text Available Meteorological data concerning the severe convective system from the 21 August 2007 are analyzed in this study. Compiled information allows to understand the reason for the storm development and to identify its fundamental convective mode. Next, the EULAG model is utilized to perform an idealized test that shows a downwind–developing storm growth in an environment comparable to the one that was observed on the 21 August 2007 in the Masurian Lake District. Finally, the COSMO numerical weather prediction model is applied to reconstruct the storm development. The experiment is carried out for various computational grids having the horizontal grid length between 7.0 and 0.55 km. It turns out that the COSMO model is capable in simulating storms of that type. Since the model is used for operational weather forecasting in Poland the evaluation of this skill contributes to the increase of public safety.

  11. Multi-parametric investigation of the volcano-hydrothermal system at Tatun Volcano Group, Northern Taiwan

    Science.gov (United States)

    Rontogianni, S.; Konstantinou, K. I.; Lin, C.-H.

    2012-07-01

    The Tatun Volcano Group (TVG) is located in northern Taiwan near the capital Taipei. In this study we selected and analyzed almost four years (2004-2007) of its seismic activity. The seismic network established around TVG initially consisted of eight three-component seismic stations with this number increasing to twelve by 2007. Local seismicity mainly involved high frequency (HF) earthquakes occurring as isolated events or as part of spasmodic bursts. Mixed and low frequency (LF) events were observed during the same period but more rarely. During the analysis we estimated duration magnitudes for the HF earthquakes and used a probabilistic non-linear method to accurately locate all these events. The complex frequencies of LF events were also analyzed with the Sompi method indicating fluid compositions consistent with a misty or dusty gas. We juxtaposed these results with geochemical/temperature anomalies extracted from fumarole gas and rainfall levels covering a similar period. This comparison is interpreted in the context of a model proposed earlier for the volcano-hydrothermal system of TVG where fluids and magmatic gases ascend from a magma body that lies at around 7-8 km depth. Most HF earthquakes occur as a response to stresses induced by fluid circulation within a dense network of cracks pervading the upper crust at TVG. The largest (ML ~ 3.1) HF event that occurred on 24 April 2006 at a depth of 5-6 km had source characteristics compatible with that of a tensile crack. It was followed by an enrichment in magmatic components of the fumarole gases as well as a fumarole temperature increase, and provides evidence for ascending fluids from a magma body into the shallow hydrothermal system. This detailed analysis and previous physical volcanology observations at TVG suggest that the region is volcanically active and that measures to mitigate potential hazards have to be considered by the local authorities.

  12. Multi-parametric investigation of the volcano-hydrothermal system at Tatun Volcano Group, Northern Taiwan

    Directory of Open Access Journals (Sweden)

    S. Rontogianni

    2012-07-01

    Full Text Available The Tatun Volcano Group (TVG is located in northern Taiwan near the capital Taipei. In this study we selected and analyzed almost four years (2004–2007 of its seismic activity. The seismic network established around TVG initially consisted of eight three-component seismic stations with this number increasing to twelve by 2007. Local seismicity mainly involved high frequency (HF earthquakes occurring as isolated events or as part of spasmodic bursts. Mixed and low frequency (LF events were observed during the same period but more rarely. During the analysis we estimated duration magnitudes for the HF earthquakes and used a probabilistic non-linear method to accurately locate all these events. The complex frequencies of LF events were also analyzed with the Sompi method indicating fluid compositions consistent with a misty or dusty gas. We juxtaposed these results with geochemical/temperature anomalies extracted from fumarole gas and rainfall levels covering a similar period. This comparison is interpreted in the context of a model proposed earlier for the volcano-hydrothermal system of TVG where fluids and magmatic gases ascend from a magma body that lies at around 7–8 km depth. Most HF earthquakes occur as a response to stresses induced by fluid circulation within a dense network of cracks pervading the upper crust at TVG. The largest (ML ~ 3.1 HF event that occurred on 24 April 2006 at a depth of 5–6 km had source characteristics compatible with that of a tensile crack. It was followed by an enrichment in magmatic components of the fumarole gases as well as a fumarole temperature increase, and provides evidence for ascending fluids from a magma body into the shallow hydrothermal system. This detailed analysis and previous physical volcanology observations at TVG suggest that the region is volcanically active and that measures to mitigate potential hazards have to be considered by the local authorities.

  13. Observations of Coastally Transitioning West African Mesoscale Convective Systems during NAMMA

    Directory of Open Access Journals (Sweden)

    Bradley W. Klotz

    2012-01-01

    Full Text Available Observations from the NASA 10 cm polarimetric Doppler weather radar (NPOL were used to examine structure, development, and oceanic transition of West African Mesoscale Convective Systems (MCSs during the NASA African Monsoon Multidisciplinary Analysis (NAMMA to determine possible indicators leading to downstream tropical cyclogenesis. Characteristics examined from the NPOL data include echo-top heights, maximum radar reflectivity, height of maximum radar reflectivity, and convective and stratiform coverage areas. Atmospheric radiosondes launched during NAMMA were used to investigate environmental stability characteristics that the MCSs encountered while over land and ocean, respectively. Strengths of African Easterly Waves (AEWs were examined along with the MCSs in order to improve the analysis of MCS characteristics. Mean structural and environmental characteristics were calculated for systems that produced TCs and for those that did not in order to determine differences between the two types. Echo-top heights were similar between the two types, but maximum reflectivity and height and coverage of intense convection (>50 dBZ are all larger than for the TC producing cases. Striking differences in environmental conditions related to future TC formation include stronger African Easterly Jet, increased moisture especially at middle and upper levels, and increased stability as the MCSs coastally transition.

  14. A synoptic climatology of derecho producing mesoscale convective systems in the North-Central Plains

    Science.gov (United States)

    Bentley, Mace L.; Mote, Thomas L.; Byrd, Stephen F.

    2000-09-01

    Synoptic-scale environments favourable for producing derechos, or widespread convectively induced windstorms, in the North-Central Plains are examined with the goal of providing pattern-recognition/diagnosis techniques. Fifteen derechos were identified across the North-Central Plains region during 1986-1995. The synoptic environment at the initiation, mid-point and decay of each derecho was then evaluated using surface, upper-air and National Center for Atmospheric Research (NCAR)/National Center for Environmental Prediction (NCEP) reanalysis datasets.Results suggest that the synoptic environment is critical in maintaining derecho producing mesoscale convective systems (DMCSs). The synoptic environment in place downstream of the MCS initiation region determines the movement and potential strength of the system. Circulation around surface low pressure increased the instability gradient and maximized leading edge convergence in the initiation region of nearly all events regardless of DMCS location or movement. Other commonalities in the environments of these events include the presence of a weak thermal boundary, high convective instability and a layer of dry low-to-mid-tropospheric air. Of the two corridors sampled, northeastward moving derechos tend to initiate east of synoptic-scale troughs, while southeastward moving derechos form on the northeast periphery of a synoptic-scale ridge. Other differences between these two DMCS events are also discussed.

  15. Chemolithoautotrophy in a shallow-sea hydrothermal system, Milos Island, Greece

    Science.gov (United States)

    Lu, G. S.; LaRowe, D.; Gilhooly, W., III; Druschel, G. K.; Fike, D. A.; Amend, J.

    2017-12-01

    In recent decades, numerous (hyper)thermophilic microorganisms have been isolated from hydrothermal venting systems. Although they have been shown to have the capabilities to catalyze a wide variety of reactions to gain energy, few pure cultures have been isolated from these environments. In order to more fully understand the catabolic potential of organisms living in and near hydrothermal vents, we have calculated the Gibbs energies (ΔGr) of 730 redox reactions that could be supplying energy to organisms in the shallow-sea hydrothermal sediments of Paleochori Bay, Milos Island, Greece. This analysis required in-depth geochemical data on the pore fluids and minerals in these sediments near the vent site at several depths. The geochemical profiles of Saganaki vent show steep gradients in temperature, pH, and redox-sensitive compounds resulting from the mixing of hot ( 75oC), acidic ( pH 4), chemically reduced venting fluid with colder, slightly basic and oxidized seawater. We determined values of ΔGr for 47 sediment porewater samples along a 20cm x 2m transect for metabolic reactions involving 23 inorganic H-, O-, C-, N-, S-, Fe-, Mn-, and As- bearing compounds. 379 of the reactions considered were exergonic at one or more sampling locations. The most exergonic reactions were anaerobic CO oxidation with NO2- (136 - 162 kJ/mol e-), followed by the O2/CO, NO3-/CO, and NO2-/ H2S redox pairs. ΔGr values exhibit significant variation among sites as temperature, pH and chemical concentration vary, especially concentrations of Fe2+, Mn2+, and H2S. A great diversity of energy sources are available for microbial populations to exploit: in hotter sediments, sulfide oxidation coupled to nitrite reduction yields large amounts of energy per kg of sediment, whereas aerobic S0 oxidation is more energy-yielding in cooler areas. Our results show that at Saganaki there is a substantial amount of energy available from to microorganisms from sulfur-redox reactions. 16S rRNA pyrotag

  16. Subseafloor Microbial Life in Venting Fluids from the Mid Cayman Rise Hydrothermal System

    Science.gov (United States)

    Huber, J. A.; Reveillaud, J.; Reddington, E.; McDermott, J. M.; Sylva, S. P.; Breier, J. A.; German, C. R.; Seewald, J.

    2012-12-01

    in Piccard vent fluids, a basalt-hosted black smoker site located at ~4950 m with a maximum temperature of 403 °C. However, hyperthermophilic and thermophilic heterotrophs of the genus Thermococcus were isolated from Piccard vent fluids, but not Von Damm. These obligate anaerobes, growing optimally at 55-90 °C, are ubiquitous at hydrothermal systems and serve as a readily cultivable indicator organism of subseafloor populations. Finally, molecular analysis of vent fluids is on-going and will define the microbial population structure in this novel ecosystem and allow for direct comparisons with other deep-sea and subsurface habitats as part of our continuing efforts to explore the deep microbial biosphere on Earth.

  17. Analysis and simulation of mesoscale convective systems accompanying heavy rainfall: The goyang case

    Science.gov (United States)

    Choi, Hyun-Young; Ha, Ji-Hyun; Lee, Dong-Kyou; Kuo, Ying-Hwa

    2011-05-01

    We investigated a torrential rainfall case with a daily rainfall amount of 379 mm and a maximum hourly rain rate of 77.5 mm that took place on 12 July 2006 at Goyang in the middlewestern part of the Korean Peninsula. The heavy rainfall was responsible for flash flooding and was highly localized. High-resolution Doppler radar data from 5 radar sites located over central Korea were analyzed. Numerical simulations using the Weather Research and Forecasting (WRF) model were also performed to complement the high-resolution observations and to further investigate the thermodynamic structure and development of the convective system. The grid nudging method using the Global Final (FNL) Analyses data was applied to the coarse model domain (30 km) in order to provide a more realistic and desirable initial and boundary conditions for the nested model domains (10 km, 3.3 km). The mesoscale convective system (MCS) which caused flash flooding was initiated by the strong low level jet (LLJ) at the frontal region of high equivalent potential temperature (θe) near the west coast over the Yellow Sea. The ascending of the warm and moist air was induced dynamically by the LLJ. The convective cells were triggered by small thermal perturbations and abruptly developed by the warm θe inflow. Within the MCS, several convective cells responsible for the rainfall peak at Goyang simultaneously developed with neighboring cells and interacted with each other. Moist absolutely unstable layers (MAULs) were seen at the lower troposphere with the very moist environment adding the instability for the development of the MCS.

  18. On the episodic nature of derecho-producing convective systems in the United States

    Science.gov (United States)

    Ashley, Walker S.; Mote, Thomas L.; Bentley, Mace L.

    2005-11-01

    Convectively generated windstorms occur over broad temporal and spatial scales; however, one of the larger-scale and most intense of these windstorms has been given the name derecho. This study illustrates the tendency for derecho-producing mesoscale convective systems to group together across the United States - forming a derecho series. The derecho series is recognized as any succession of derechos that develop within a similar synoptic environment with no more than 72 h separating individual events. A derecho dataset for the period 1994-2003 was assembled to investigate the groupings of these extremely damaging convective wind events. Results indicate that over 62% of the derechos in the dataset were members of a derecho series. On average, nearly six series affected the United States annually. Most derecho series consisted of two or three events; though, 14 series during the period of record contained four or more events. Two separate series involved nine derechos within a period of nine days. Analyses reveal that derecho series largely frequent regions of the Midwest, Ohio Valley, and the south-central Great Plains during May, June, and July. Results suggest that once a derecho occurred during May, June, or July, there was a 58% chance that this event was the first of a series of two or more, and about a 46% chance that this was the first of a derecho series consisting of three or more events. The derecho series climatology reveals that forecasters in regions frequented by derechos should be prepared for the probable regeneration of a derecho-producing convective system after an initial event occurs. Copyright

  19. Al-doped SnO2 nanocrystals from hydrothermal systems

    International Nuclear Information System (INIS)

    Jin Haiying; Xu Yaohua; Pang Guangsheng; Dong Wenjun; Wan Qiang; Sun Yan; Feng Shouhua

    2004-01-01

    Nanoparticles of Al-doped SnO 2 have been hydrothermally synthesized. The influences of the hydrothermal reaction time, the molar ratio of Sn/Al as well as the pH value of the solution have been studied. During the hydrothermal synthesis, the particle's core is rich in Sn and the surface is rich in Al. The Al-rich surface prevents the particles from further growing up either in the hydrothermal condition or during the calcination at 600 deg. C for a short period of time. The optimal hydrothermal synthesis condition of the nanoparticles is pH 5, Sn/Al=4:1 and 12 h at 160 deg. C. The products have been studied by XRD, TEM and 27 Al solid-state NMR

  20. Chemical variation in hydrothermal minerals of the Los Humeros geothermal system, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Serrano, R.G. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico). Insituto de Geofisica

    2002-10-01

    The Los Humeros geothermal system is composed of more than 2200 m of Quaternary altered volcanic rocks and an underlying Cretaceous sedimentary sequence. The low salinity of the fluids discharged at present (Na{sup +} and Cl{sup -} concentrations <500 ppm), and the excess steam, indicate that the reservoir contains a mixture of steam and dilute groundwater. Water-rock equilibrium is not attained. Hydrothermal minerals are present in veinlets, vugs, and replacing primary minerals. Three mineral zones are recognized: 1) a shallow argillic zone (<400 m depth), 2) a propylitic zone (ranging between 500 and 1800 m) and 3) a skarn zone (>1800 m). Petrographic examination of cuttings from five wells and temperature data indicate at least two stages of hydrothermal activity. Temperature is the main factor that affects the chemical composition of chlorite, epidote and biotite. Fe{sup 2+} and Al{sup IV} increase in chlorite with temperature [from 1.4 formula position unit (fpu) to 2.8, and from 0.7 to 2.4 fpu, respectively]. The pistacite content of epidote varies from 18 to 33 mol% in high-temperature regions (>270 {sup o}C) and from 13 to 26 mol% in low-temperature regions (<250 {sup 0}C). Biotite displays a slight increase in Al{sup IV} contents (1.55-2.8) and octahedral occupancy (5.93-6.0 fpu) with temperature. Whole rock composition and variations in oxygen fugacity condition are factors that also affect the concentrations of Fe, Al and Mg in the octahedral sites of chlorite, epidote, biotite and amphiboles. Chemical variations observed in alteration minerals at different depths in the Colapso Central-Xalapazco region could be used as indicator of relict physico-chemical conditions in the reservoir, before the present economic exploitation. (author)

  1. Refining the Subseafloor Circulation Model of the Middle Valley Hydrothermal System Using Fluid Geochemistry

    Science.gov (United States)

    Inderbitzen, K. E.; Wheat, C. G.; Baker, P. A.; Fisher, A. T.

    2014-12-01

    Currently, fluid circulation patterns and the evolution of rock/fluid compositions as circulation occurs in subseafloor hydrothermal systems are poorly constrained. Sedimented spreading centers provide a unique opportunity to study subsurface flow because sediment acts as an insulating blanket that traps heat from the cooling magma body and limits: (a) potential flow paths for seawater to recharge the aquifer in permeable upper basaltic basement and (b) points of altered fluid egress. This also allows for a range of thermal and geochemical gradients to exist near the sediment-water interface. Models of fluid circulation patterns in this type of hydrologic setting have been generated (eg. Stein and Fisher, 2001); however fluid chemistry datasets have not previously been used to test the model's viability. We address this issue by integrating the existing circulation model with fluid compositional data collected from sediment pore waters and high temperature hydrothermal vents located in Middle Valley on the Juan de Fuca Ridge. Middle Valley hosts a variety of hydrologic regimes: including areas of fluid recharge (Site 855), active venting (Site 858/1036; Dead Dog vent field), recent venting (Site 856/1035; Bent Hill Massive Sulfide deposit) and a section of heavily sedimented basement located between recharge and discharge sites (Site 857). We will present new results based on thermal and geochemical data from the area of active venting (Sites 858 and 1036), that was collected during Ocean Drilling Program Legs 139 and 169 and a subsequent heat flow/gravity coring effort. These results illuminate fine scale controls on secondary recharge and fluid flow within the sediment section at Site 858/1036. The current status of high temperature vents in this area (based on observations made in July, 2014) will also be outlined.

  2. Metabasalts from the Mid-Atlantic Ridge: new insights into hydrothermal systems in slow-spreading crust

    Science.gov (United States)

    Gillis, Kathryn M.; Thompson, Geoffrey

    1993-12-01

    An extensive suite of hydrothermally altered rocks were recovered by Alvin and dredging along the MARK [Mid-Atlantic Ridge, south of the Kane Fracture Zone (23 24°N)] where detachment faulting has provided a window into the crustal component of hydrothermal systems. Rocks of basaltic composition are altered to two assemblages with these characteristics: (i) type I: albitic plagioclase (An02 10)+mixed-layer smectite/chlorite or chlorite±actinolite±quartz±sphene, 20% of the clinopyroxene is altered, and Cu and Zn are leached. The geochemical signature of these alteration types reflects the relative proportion and composition of secondary minerals, and the degree of alteration of primary phases, and does not show simple predictive relationships. Element mobilities indicate that both alteration types formed at low water/rock ratios. The MARK assemblages are typical of the greenschist and transition to the amphibolite facies, and represent two distinct, albeit overlapping, temperature regimes: type I-180 to 300°C and type II-250 to 450°C. By analogy with DSDP/ODP Hole 504B and many ophiolites, the MARK metabasalts were altered within the downwelling limb of a hydrothermal cell and type I and II samples formed in the upper and lower portions of the sheeted like complex, respectively. Episodic magmatic and hydrothermal events at slow-spreading ridges suggest that these observed mineral assemblages represent the cumulative effects of more than one hydrothermal event. Groundmass and vein assemblages in the MARK metabasalts indicate either that alteration conditions did not change during successive hydrothermal events or that these assemblages record only the highest temperature event. Lack of retrograde reactions or overprinting of lower temperature assemblages (e.g., zeolites) suggests that there is a continuum in alteration conditions while crustal segments remain in the ridge axis environment. The type II samples may be representative of the reaction zone where

  3. Thermal Sizing of Heat Exchanger Tubes for Air Natural Convective Cooling System of Emergency Cooling Tank

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myoung Jun; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of); Moon, Joo Hyung; Bae, Youngmin; Kim, Youngin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    For the long operation of secondary passive cooling system, however, water level goes down by evaporation in succession at emergency cooling tank. At the end there would be no place to dissipate heat from condensation heat exchanger. Therefore, steam cooling heat exchanger is put on the top of emergency cooling tank to maintain appropriate water level by collecting evaporating steam. Steam cooling heat exchanger is installed inside an air chimney and evaporated steam is cooled down by air natural convection. In this study, thermal sizing of steam cooling heat exchanger under air natural convection was conducted by TSCON program for the design of experimental setup as shown in Fig. 2. Thermal sizing of steam cooling heat exchanger tube under air natural convection was conducted by TSCON program for the design of experimental setup. 25 - 1' tubes which has a length 1687 mm was determined as steam cooling heat exchanger at 2 kW heat load and 100 liter water pool in emergency cooling tank (experimental limit condition). The corresponding width of two tubes is 50 mm and has 5 by 5 tube array for heat exchanger.

  4. Thermal Sizing of Heat Exchanger Tubes for Air Natural Convective Cooling System of Emergency Cooling Tank

    International Nuclear Information System (INIS)

    Kim, Myoung Jun; Lee, Hee Joon; Moon, Joo Hyung; Bae, Youngmin; Kim, Youngin

    2014-01-01

    For the long operation of secondary passive cooling system, however, water level goes down by evaporation in succession at emergency cooling tank. At the end there would be no place to dissipate heat from condensation heat exchanger. Therefore, steam cooling heat exchanger is put on the top of emergency cooling tank to maintain appropriate water level by collecting evaporating steam. Steam cooling heat exchanger is installed inside an air chimney and evaporated steam is cooled down by air natural convection. In this study, thermal sizing of steam cooling heat exchanger under air natural convection was conducted by TSCON program for the design of experimental setup as shown in Fig. 2. Thermal sizing of steam cooling heat exchanger tube under air natural convection was conducted by TSCON program for the design of experimental setup. 25 - 1' tubes which has a length 1687 mm was determined as steam cooling heat exchanger at 2 kW heat load and 100 liter water pool in emergency cooling tank (experimental limit condition). The corresponding width of two tubes is 50 mm and has 5 by 5 tube array for heat exchanger

  5. Constraints on the source of Cu in a submarine magmatic-hydrothermal system, Brothers volcano, Kermadec island arc

    Science.gov (United States)

    Keith, Manuel; Haase, Karsten M.; Klemd, Reiner; Smith, Daniel J.; Schwarz-Schampera, Ulrich; Bach, Wolfgang

    2018-05-01

    Most magmatic-hydrothermal Cu deposits are genetically linked to arc magmas. However, most continental or oceanic arc magmas are barren, and hence new methods have to be developed to distinguish between barren and mineralised arc systems. Source composition, melting conditions, the timing of S saturation and an initial chalcophile element-enrichment represent important parameters that control the potential of a subduction setting to host an economically valuable deposit. Brothers volcano in the Kermadec island arc is one of the best-studied examples of arc-related submarine magmatic-hydrothermal activity. This study, for the first time, compares the chemical and mineralogical composition of the Brothers seafloor massive sulphides and the associated dacitic to rhyolitic lavas that host the hydrothermal system. Incompatible trace element ratios, such as La/Sm and Ce/Pb, indicate that the basaltic melts from L'Esperance volcano may represent a parental analogue to the more evolved Brothers lavas. Copper-rich magmatic sulphides (Cu > 2 wt%) identified in fresh volcanic glass and phenocryst phases, such as clinopyroxene, plagioclase and Fe-Ti oxide suggest that the surrounding lavas that host the Brothers hydrothermal system represent a potential Cu source for the sulphide ores at the seafloor. Thermodynamic calculations reveal that the Brothers melts reached volatile saturation during their evolution. Melt inclusion data and the occurrence of sulphides along vesicle margins indicate that an exsolving volatile phase extracted Cu from the silicate melt and probably contributed it to the overlying hydrothermal system. Hence, the formation of the Cu-rich seafloor massive sulphides (up to 35.6 wt%) is probably due to the contribution of Cu from a bimodal source including wall rock leaching and magmatic degassing, in a mineralisation style that is hybrid between Cyprus-type volcanic-hosted massive sulphide and subaerial epithermal-porphyry deposits.

  6. Study and Application of Forced Convection in Road Bus Heating System

    Directory of Open Access Journals (Sweden)

    Scheila Sandi Biazus

    2015-03-01

    Full Text Available This work deals with a replacing the heating system of intercity buses, made by long heat exchangers distributed on the sides of the passenger saloon by small and compact ones that use forced convection to heat dissipation. At the beginning the calculation was made of the heat capacity of a heat exchanger with the parameters defined by the supplier, and then conducted an analysis of change in these parameters in order to improve its efficiency. The method for examining the heat exchanger is based on the correlations available in the convection flow inside and outside to determine the respective convective coefficients, and therefore the overall coefficient of heat transfer. Following, the heat exchanger in its original form, was tested on bench. Thus, from the thermal load of the bus model studied, the amount of exchangers required has been defined to satisfy the thermal comfort of passengers. Field tests of the heating systems with new heat exchangers were performed to obtain actual data of the proposed system. The original factory system showed to be efficient in meeting the needs thermal load and economically viable, such that the critical thermal load can be met with ten heaters installed along the body. Furthermore, this system offers the possibility of varying the parameters to best fit to the project, where the flow variation of the fans or the spacing between the fins of the heat exchanger decreases the amount of heaters required. At the same time, the system showed the need for further study to assess its distribution along the passenger saloon in order to meet a best uniformity temperature distribution.

  7. The Impact of Microphysics on Intensity and Structure of Hurricanes and Mesoscale Convective Systems

    Science.gov (United States)

    Tao, Wei-Kuo; Shi, Jainn J.; Jou, Ben Jong-Dao; Lee, Wen-Chau; Lin, Pay-Liam; Chang, Mei-Yu

    2007-01-01

    During the past decade, both research and operational numerical weather prediction models, e.g. Weather Research and Forecast (WRF) model, have started using more complex microphysical schemes originally developed for high-resolution cloud resolving models (CRMs) with a 1-2 km or less horizontal resolutions. WRF is a next-generation mesoscale forecast model and assimilation system that has incorporated modern software framework, advanced dynamics, numeric and data assimilation techniques, a multiple moveable nesting capability, and improved physical packages. WRF model can be used for a wide range of applications, from idealized research to operational forecasting, with an emphasis on horizontal grid sizes in the range of 1-10 km. The current WRF includes several different microphysics options such as Purdue Lin et al. (1983), WSM 6-class and Thompson microphysics schemes. We have recently implemented three sophisticated cloud microphysics schemes into WRF. The cloud microphysics schemes have been extensively tested and applied for different mesoscale systems in different geographical locations. The performances of these schemes have been compared to those from other WRF microphysics options. We are performing sensitivity tests in using WRF to examine the impact of six different cloud microphysical schemes on precipitation processes associated hurricanes and mesoscale convective systems developed at different geographic locations [Oklahoma (IHOP), Louisiana (Hurricane Katrina), Canada (C3VP - snow events), Washington (fire storm), India (Monsoon), Taiwan (TiMREX - terrain)]. We will determine the microphysical schemes for good simulated convective systems in these geographic locations. We are also performing the inline tracer calculation to comprehend the physical processes (i.e., boundary layer and each quadrant in the boundary layer) related to the development and structure of hurricanes and mesoscale convective systems.

  8. Comparative assessment of five potential sites for hydrothermal magma systems: geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    White, A.F.

    1980-08-01

    A brief discussion is given of the geochemical objectives and questions that must be addressed in such an evaluation. A summary of the currently published literature that is pertinent in answering these questions is presented for each of the five areas: The Geysers-Clear Lake region, Long Valley, Rio Grand Rift, Roosevelt Hot Springs, and the Salton Trough. The major geochemical processes associated with proposed hydrothermal sites are categorized into three groups for presentation: geochemistry of magma and associated volcanic rocks, geochemistry of hydrothermal solutions, and geochemistry of hydrothermal alteration. (MHR)

  9. Revisiting the Euganean Geothermal System (NE Italy) - insights from large scale hydrothermal modelling

    Science.gov (United States)

    Pola, Marco; Cacace, Mauro; Fabbri, Paolo; Piccinini, Leonardo; Zampieri, Dario; Dalla Libera, Nico

    2017-04-01

    As one of the largest and most extensive utilized geothermal system in northern Italy, the Euganean Geothermal System (EGS, Veneto region, NE Italy) has long been the subject of still ongoing studies. Hydrothermal waters feeding the system are of meteoric origin and infiltrate in the Veneto Prealps, to the north of the main geothermal area. The waters circulate for approximately 100 km in the subsurface of the central Veneto, outflowing with temperatures from 65°C to 86°C to the southwest near the cities of Abano Terme and Montegrotto Terme. The naturally emerging waters are mainly used for balneotherapeutic purposes, forming the famous Euganean spa district. This preferential outflow is thought to have a relevant structural component producing a high secondary permeability localized within an area of limited extent (approx. 25 km2). This peculiar structure is associated with a local network of fractures resulting from transtentional tectonics of the regional Schio-Vicenza fault system (SVFS) bounding the Euganean Geothermal Field (EGF). In the present study, a revised conceptual hydrothermal model for the EGS based on the regional hydrogeology and structural geology is proposed. Particularly, this work aims to quantify: (1) the role of the regional SVFS, and (2) the impact of the high density local fractures mesh beneath the EGF on the regional-to-local groundwater flow circulation at depths and its thermal configuration. 3D coupled flow and heat transport numerical simulations inspired by the newly developed conceptual model are carried out to properly quantify the results from these interactions. Consistently with the observations, the obtained results provide indication for temperatures in the EGF reservoir being higher than in the surrounding areas, despite a uniform basal regional crustal heat inflow. In addition, they point to the presence of a structural causative process for the localized outflow, in which deep-seated groundwater is preferentially

  10. Convective Systems Over the Japan Sea: Cloud-Resolving Model Simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Yoshizaki, Masanori; Shie, Chung-Lin; Kato, Teryuki

    2002-01-01

    Wintertime observations of MCSs (Mesoscale Convective Systems) over the Sea of Japan - 2001 (WMO-01) were collected from January 12 to February 1, 2001. One of the major objectives is to better understand and forecast snow systems and accompanying disturbances and the associated key physical processes involved in the formation and development of these disturbances. Multiple observation platforms (e.g., upper-air soundings, Doppler radar, wind profilers, radiometers, etc.) during WMO-01 provided a first attempt at investigating the detailed characteristics of convective storms and air pattern changes associated with winter storms over the Sea of Japan region. WMO-01 also provided estimates of the apparent heat source (Q1) and apparent moisture sink (Q2). The vertical integrals of Q1 and Q2 are equal to the surface precipitation rates. The horizontal and vertical adjective components of Q1 and Q2 can be used as large-scale forcing for the Cloud Resolving Models (CRMs). The Goddard Cumulus Ensemble (GCE) model is a CRM (typically run with a 1-km grid size). The GCE model has sophisticated microphysics and allows explicit interactions between clouds, radiation, and surface processes. It will be used to understand and quantify precipitation processes associated with wintertime convective systems over the Sea of Japan (using data collected during the WMO-01). This is the first cloud-resolving model used to simulate precipitation processes in this particular region. The GCE model-simulated WMO-01 results will also be compared to other GCE model-simulated weather systems that developed during other field campaigns (i.e., South China Sea, west Pacific warm pool region, eastern Atlantic region and central USA).

  11. Asymmetrical structure, hydrothermal system and edifice stability: The case of Ubinas volcano, Peru, revealed by geophysical surveys

    Science.gov (United States)

    Gonzales, Katherine; Finizola, Anthony; Lénat, Jean-François; Macedo, Orlando; Ramos, Domingo; Thouret, Jean-Claude; Fournier, Nicolas; Cruz, Vicentina; Pistre, Karine

    2014-04-01

    Ubinas volcano, the historically most active volcano in Peru straddles a low-relief high plateau and the flank of a steep valley. A multidisciplinary geophysical study has been performed to investigate the internal structure and the fluids flow within the edifice. We conducted 10 self-potential (SP) radial (from summit to base) profiles, 15 audio magnetotelluric (AMT) soundings on the west flank and a detailed survey of SP and soil temperature measurements on the summit caldera floor. The typical “V” shape of the SP radial profiles has been interpreted as the result of a hydrothermal zone superimposed on a hydrogeological zone in the upper parts of the edifice, and depicts a sub-circular SP positive anomaly, about 6 km in diameter. The latter is centred on the summit, and is characterised by a larger extension on the western flank located on the low-relief high plateau. The AMT resistivity model shows the presence of a conductive body beneath the summit at a depth comparable to that of the bottom of the inner south crater in the present-day caldera, where intense hydrothermal manifestations occur. The lack of SP and temperature anomalies on the present caldera floor suggests a self-sealed hydrothermal system, where the inner south crater acts as a pressure release valve. Although no resistivity data exists on the eastern flank, we presume, based on the asymmetry of the basement topography, and the amplitude of SP anomalies on the east flank, which are approximately five fold that on the west flank, that gravitational flow of hydrothermal fluids may occur towards the deep valley of Ubinas. This hypothesis, supported by the presence of hot springs and faults on the eastern foot of the edifice, reinforces the idea that a large part of the southeast flank of the Ubinas volcano may be altered by hydrothermal activity and will tend to be less stable. One of the major findings that stems from this study is that the slope of the basement on which a volcano has grown

  12. A seismic network to investigate the sedimentary hosted hydrothermal Lusi system

    Science.gov (United States)

    Javad Fallahi, Mohammad; Mazzini, Adriano; Lupi, Matteo; Obermann, Anne; Karyono, Karyono

    2016-04-01

    The 29th of May 2006 marked the beginning of the sedimentary hosted hydrothermal Lusi system. During the last 10 years we witnessed numerous alterations of the Lusi system behavior that coincide with the frequent seismic and volcanic activity occurring in the region. In order to monitor the effect that the seismicity and the activity of the volcanic arc have on Lusi, we deployed a ad hoc seismic network. This temporary network consist of 10 broadband and 21 short period stations and is currently operating around the Arjuno-Welirang volcanic complex, along the Watukosek fault system and around Lusi, in the East Java basin since January 2015. We exploit this dataset to investigate surface wave and shear wave velocity structure of the upper-crust beneath the Arjuno-Welirang-Lusi complex in the framework of the Lusi Lab project (ERC grant n° 308126). Rayleigh and Love waves travelling between each station-pair are extracted by cross-correlating long time series of ambient noise data recorded at the stations. Group and phase velocity dispersion curves are obtained by time-frequency analysis of cross-correlation functions, and are tomographically inverted to provide 2D velocity maps corresponding to different sampling depths. 3D shear wave velocity structure is then acquired by inverting the group velocity maps.

  13. Energy models for generation planning and midterm operation of hydrothermal power systems

    Energy Technology Data Exchange (ETDEWEB)

    Amthauer, E

    1981-01-01

    The aims of generation planning and midterm operation of a power system are reliable and economical load coverage at any moment. For solving some of the planning tasks, it is advantageous to use energy models, if a large amount of power is installed in hydro-storage plants. Energy models apply the probability of load coverage in a given period as a quantitative measure for a power system's reliability provided the availability of the transmission network is given. Reliability may be influenced by installing new plants (longterm) or by committing the existing plants in a particular fashion. An evaluation of these activities makes it possible to determine decisions which optimize a given object function. In this thesis, energy models for the Swiss hydrothermal power system are derived and tested by simulation. For this utility, energy supply during the emptying period of the storage plants in winter is of special interest. Therefore, the criteria for generation planning are derived by analysing the distribution functions of future energy balances in winter periods. The committment of the existing plants and energy exchange with other utilities in a straight following winter period are planned by means of a sequential decision process. It is shown how strategies for these planning tasks are found with the models. Those model parameters, having the highest influence on reliable and economical load coverage are extracted by means of sensitivity analysis.

  14. Microbial biofilms control economic metal mobility in an acid-sulfate hydrothermal system

    Science.gov (United States)

    Phillips-Lander, C. M.; Roberts, J. A.; Hernandez, W.; Mora, M.; Fowle, D. A.

    2012-12-01

    Trace metal cycling in hydrothermal systems has been the subject of a variety of geochemical and economical geology studies. Typically in these settings these elements are sequestered in sulfide and oxide mineral fractions, however in near-surface low-temperature environments organic matter and microorganisms (typically in mats) have been implicated in their mobility through sorption. Here we specifically examine the role of microbial biofilms on metal partitioning in an acid-sulfate hydrothermal system. We studied the influence of microorganisms and microbial biofilms on trace metal adsorption in Pailas de Aguas I, an acid-sulfate hot spring on the southwest flank of Rincon de la Vieja, a composite stratovolcano in the Guanacaste Province, Costa Rica. Spring waters contain high suspended loads, and are characterized by high T (79.6-89.3oC), low pH (2.6-4), and high ionic strengths (I= 0.5-0.8). Waters contain high concentrations of the biogeochemically active elements Fe (4-6 mmol/l) and SO42- (38 mmol/l), but PO43- are below detection limits (bdl). Silver, Ni, and Mo concentrations are bdl; however other trace metals are present in solution in concentrations of 0.1-0.2 mg/l Cd, 0.2-0.4 mg/l Cr and V, 0.04-1 mg/l Cu,. Preliminary 16S rRNA analyses of microorganisms in sediments reveal several species of algae, including Galderia sp., Cyanidium sp, γ-proteobacteria, Acidithiobacillus caldus, Euryarcheota, and methanogens. To evaluate microbial biofilms' impact on trace metal mobility we analyzed a combination of suspended, bulk and biofilm associated sediment samples via X-ray diffraction (XRD) and trace element sequential extractions (SE). XRD analysis indicated all samples were primarily composed of Fe/Al clay minerals (nontronite, kaolinite), 2- and 6-line ferrihydrite, goethite, and hematite, quartz, and opal-α. SE showed the highest concentrations of Cu, Mo, and V were found in the suspended load. Molybdenum was found primarily in the residual and organic

  15. Application of oxygen and hydrogen isotopes of waters in Tengchong hydrothermal systems of China

    International Nuclear Information System (INIS)

    Shen Minzi; Hou Fagao; Lin Ruifen; Ni Baoling

    1988-01-01

    This paper summarizes the results obtained for hydrothermal systems in Tengchong by using deuterium, oxygen-18 and tritium as natural tracers. On the basis of deuterium and oxygen-18 analyses of 69 thermal springs and some other meteoric, surface and underground water samples it has been confirmed that all geothermal waters are originally meteoric, but the δD of hot spring waters is often lighter than that of local surface and underground waters. It seems that the recharging water is from higher elevations and far from the thermal areas. The differences in oxygen-18 and deuterium contents between thermal springs and deep thermal waters have been calculated for single-stage steam separation from 276 deg. C to 96 deg. C. The oxygen isotope shift of deep thermal water produced by water-rock reactions is of 1.57 per mille and part of the observed oxygen isotope shift of thermal springs seems to have occurred due to subsurface boiling. The tritium content ( 18 O three subsurface processes would have been distinguished, they are subsurface boiling, mixing-subsurface boiling and subsurface boiling-mixing. The springs formed by subsurface boiling have tritium content of less than 5 TU. The tritium content of 5-10 TU is for springs formed by mixing-subsurface boiling and 10-20 TU is for subsurface boiling-mixing. The tritium content of geothermal water in Hot Sea, geothermal field seems higher than that of the Geysers U.S.A. and Wairakei N.Z. It would show that the circulation time of the thermal water in Hot Sea geothermal system is not so long, the reservoir is quite good with percolation and the recharging water is sufficiently enough. The most important applications of oxygen and hydrogen isotopes of water in geothermal study are in two ways, as tracers of water origins and as tracers of reservoir processes. This paper discussed these two aspects of Tengchong hydrothermal systems. 6 refs, 6 figs, 5 tabs

  16. Neuro-Fuzzy Computational Technique to Control Load Frequency in Hydro-Thermal Interconnected Power System

    Science.gov (United States)

    Prakash, S.; Sinha, S. K.

    2015-09-01

    In this research work, two areas hydro-thermal power system connected through tie-lines is considered. The perturbation of frequencies at the areas and resulting tie line power flows arise due to unpredictable load variations that cause mismatch between the generated and demanded powers. Due to rising and falling power demand, the real and reactive power balance is harmed; hence frequency and voltage get deviated from nominal value. This necessitates designing of an accurate and fast controller to maintain the system parameters at nominal value. The main purpose of system generation control is to balance the system generation against the load and losses so that the desired frequency and power interchange between neighboring systems are maintained. The intelligent controllers like fuzzy logic, artificial neural network (ANN) and hybrid fuzzy neural network approaches are used for automatic generation control for the two area interconnected power systems. Area 1 consists of thermal reheat power plant whereas area 2 consists of hydro power plant with electric governor. Performance evaluation is carried out by using intelligent (ANFIS, ANN and fuzzy) control and conventional PI and PID control approaches. To enhance the performance of controller sliding surface i.e. variable structure control is included. The model of interconnected power system has been developed with all five types of said controllers and simulated using MATLAB/SIMULINK package. The performance of the intelligent controllers has been compared with the conventional PI and PID controllers for the interconnected power system. A comparison of ANFIS, ANN, Fuzzy and PI, PID based approaches shows the superiority of proposed ANFIS over ANN, fuzzy and PI, PID. Thus the hybrid fuzzy neural network controller has better dynamic response i.e., quick in operation, reduced error magnitude and minimized frequency transients.

  17. Production of fuel range oxygenates by supercritical hydrothermal liquefaction of lignocellulosic model systems

    DEFF Research Database (Denmark)

    Pedersen, Thomas Helmer; Rosendahl, Lasse Aistrup

    2015-01-01

    Lignocellulosic model compounds and aspen wood are processed at supercritical hydrothermal conditions to study and understand feedstock impact on biocrude formation and characteristics. Glucose and xylose demonstrate similar yield of biocrude and biochar, similar biocrude characteristics, and it ......Lignocellulosic model compounds and aspen wood are processed at supercritical hydrothermal conditions to study and understand feedstock impact on biocrude formation and characteristics. Glucose and xylose demonstrate similar yield of biocrude and biochar, similar biocrude characteristics...

  18. Surface-discharging hydrothermal systems at Yucca Mountain: Examining the evidence

    International Nuclear Information System (INIS)

    Levy, S.S.

    1992-01-01

    This paper discusses exposures of altered rock that have been thought to form by recent discharge of water from depth. They were examined to address a concern that hydrothermal processes could compromise the isolation capability of a potential high-level nuclear waste repository at Yucca Mountain. Suspected hot-spring and hydrothermal-vent deposits are more likely the products of infiltration of meteoric water into newly deposited and still-hot pyroclastic flows >12 Myr ago

  19. Organizational Modes of Severe Wind-producing Convective Systems over North China

    Science.gov (United States)

    Yang, Xinlin; Sun, Jianhua

    2018-05-01

    Severe weather reports and composite radar reflectivity data from 2010-14 over North China were used to analyze the distribution of severe convective wind (SCW) events and their organizational modes of radar reflectivity. The six organizational modes for SCW events (and their proportions) were cluster cells (35.4%), squall lines (18.4%), nonlinear-shaped systems (17.8%), broken lines (11.6%), individual cells (1.2%), and bow echoes (0.5%). The peak month for both squall lines and broken lines was June, whereas it was July for the other four modes. The highest numbers of SCW events were over the mountains, which were generally associated with disorganized systems of cluster cells. In contrast, SCW associated with linear systems occurred mainly over the plains, where stations recorded an average of less than one SCW event per year. Regions with a high frequency of SCW associated with nonlinear-shaped systems also experienced many SCW events associated with squall lines. Values of convective available potential energy, precipitable water, 0-3-km shear, and 0-6-km shear, were demonstrably larger over the plains than over the mountains, which had an evident effect on the organizational modes of SCW events. Therefore, topography may be an important factor in the organizational modes for SCW events over North China.

  20. Research on Vehicle Temperature Regulation System Based on Air Convection Principle

    Science.gov (United States)

    Zhuge, Muzi; Li, Xiang; Liang, Caifeng

    2018-03-01

    The long time parking outdoors in the summer will lead to too high temperature in the car, and the harmful gas produced by the vehicle engine will stay in the confined space for a long time during the parking process, which will do great harm to the human body. If the air conditioning system is turned on before driving, the cooling rate is slow and the battery loss is large. To solve the above problems, we designed a temperature adjusting system based on the principle of air convection. We can choose the automatic mode or manual mode to achieve control of a convection window. In the automatic mode, the system will automatically detect the environmental temperature, through the sensor to complete the detection, and the signal is transmitted to the microcontroller to control the window open or close, in manual mode, the remote control of the window can be realized by Bluetooth. Therefore, the system has important practical significance to effectively regulate temperature, prolong battery life, and improve the safety and comfort of traffic vehicles.

  1. Numerical analysis of natural convection in a double-layer immiscible system

    International Nuclear Information System (INIS)

    Gubaidullin, A.A.; Sehgal, B.R.

    2001-01-01

    In the present paper numerical analysis has been applied to study the natural convection heat transfer in a system composed of two immiscible fluids with uniform internal heat generation in the lower layer or in both layers enclosed in a rectangular or in a semi-circular vessel. The objective of the work is to perform a parametric study to assess the effect of physical properties on the heat transfer characteristics as well as to complement results obtained from experiments by means of CFD simulations for a range of lower Rayleigh number and combine the experimental data and the computational results. (author)

  2. Burnout in boiling heat transfer. II. Subcooled and low-quality forced-convection systems

    International Nuclear Information System (INIS)

    Bergles, A.E.

    1977-01-01

    Recent experimental and analytical developments regarding burnout in subcooled and low-quality forced-convection systems are reviewed. Many data have been accumulated which clarify the parametric trends and lead to new design correlations for water and a variety of other coolants in both simple and complex geometries. A number of critical experiments and models have been developed to attempt to clarify the burnout mechanism(s) in simpler geometries. Other topics discussed include burnout with power transients and techniques to augment burnout. 86 references

  3. Mass transfer processes in a post eruption hydrothermal system: Parameterisation of microgravity changes at Te Maari craters, New Zealand

    Science.gov (United States)

    Miller, Craig A.; Currenti, Gilda; Hamling, Ian; Williams-Jones, Glyn

    2018-05-01

    Fluid transfer and ground deformation at hydrothermal systems occur both as a precursor to, or as a result of, an eruption. Typically studies focus on pre-eruption changes to understand the likelihood of unrest leading to eruption; however, monitoring post-eruption changes is important for tracking the return of the system towards background activity. Here we describe processes occurring in a hydrothermal system following the 2012 eruption of Upper Te Maari crater on Mt Tongariro, New Zealand, from observations of microgravity change and deformation. Our aim is to assess the post-eruption recovery of the system, to provide a baseline for long-term monitoring. Residual microgravity anomalies of up to 92 ± 11 μGal per year are accompanied by up to 0.037 ± 0.01 m subsidence. We model microgravity changes using analytic solutions to determine the most likely geometry and source location. A multiobjective inversion tests whether the gravity change models are consistent with the observed deformation. We conclude that the source of subsidence is separate from the location of mass addition. From this unusual combination of observations, we develop a conceptual model of fluid transfer within a condensate layer, occurring in response to eruption-driven pressure changes. We find that depressurisation drives the evacuation of pore fluid, either exiting the system completely as vapour through newly created vents and fumaroles, or migrating to shallower levels where it accumulates in empty pore space, resulting in positive gravity changes. Evacuated pores then collapse, causing subsidence. In addition we find that significant mass addition occurs from influx of meteoric fluids through the fractured hydrothermal seal. Long-term combined microgravity and deformation monitoring will allow us to track the resealing and re-pressurisation of the hydrothermal system and assess what hazard it presents to thousands of hikers who annually traverse the volcano, within 2 km of the

  4. Dynamics and mass transport of solutal convection in a closed porous media system

    Science.gov (United States)

    Wen, Baole; Akhbari, Daria; Hesse, Marc

    2016-11-01

    Most of the recent studies of CO2 sequestration are performed in open systems where the constant partial pressure of CO2 in the vapor phase results in a time-invariant saturated concentration of CO2 in the brine (Cs). However, in some closed natural CO2 reservoirs, e.g., Bravo Dome in New Mexico, the continuous dissolution of CO2 leads to a pressure drop in the gas that is accompanied by a reduction of Cs and thereby affects the dynamics and mass transport of convection in the brine. In this talk, I discuss the characteristics of convective CO2 dissolution in a closed system. The gas is assumed to be ideal and its solubility given by Henry's law. An analytical solution shows that the diffusive base state is no longer self-similar and that diffusive mass transfer declines rapidly. Scaling analysis reveals that the volume ratio of brine and gas η determines the behavior of the system. DNS show that no constant flux regime exists for η > 0 nevertheless, the quantity F /Cs2 remains constant, where F is the dissolution flux. The onset time is only affected by η when the Rayleigh number Ra is small. In this case, the drop in Cs during the initial diffusive regime significantly reduces the effective Ra and therefore delays the onset.

  5. Statistical Analysis and ETAS Modeling of Seismicity Induced by Production of Geothermal Energy from Hydrothermal Systems

    Science.gov (United States)

    Dinske, C.; Langenbruch, C.; Shapiro, S. A.

    2017-12-01

    We investigate seismicity related to hydrothermal systems in Germany and Italy, focussing on temporal changes of seismicity rates. Our analysis was motivated by numerical simulations The modeling of stress changes caused by the injection and production of fluid revealed that seismicity rates decrease on a long-term perspective which is not observed in the considered case studies. We analyze the waiting time distributions of the seismic events in both time domain (inter event times) and fluid volume domain (inter event volume). We find clear indications that the observed seismicity comprises two components: (1) seismicity that is directly triggered by production and re-injection of fluid, i.e. induced events, and (2) seismicity that is triggered by earthquake interactions, i.e. aftershock triggering. In order to better constrain our numerical simulations using the observed induced seismicity we apply catalog declustering to seperate the two components. We use the magnitude-dependent space-time windowing approach introduced by Gardner and Knopoff (1974) and test several published algorithms to calculate the space-time windows. After declustering, we conclude that the different hydrothermal reservoirs show a comparable seismic response to the circulation of fluid and additional triggering by earthquake interactions. The declustered catalogs contain approximately 50 per cent of the number of events in the original catalogs. We then perform ETAS (Epidemic Type Aftershock; Ogata, 1986, 1988) modeling for two reasons. First, we want to know whether the different reservoirs are also comparable regarding earthquake interaction patterns. Second, if we identify systematic patterns, ETAS modeling can contribute to forecast seismicity during production of geothermal energy. We find that stationary ETAS models cannot accurately capture real seismicity rate changes. One reason for this finding is given by the rate of observed induced events which is not constant over time. Hence

  6. The Cocos Ridge hydrothermal system revealed by microthermometry of fluid and melt inclusions

    Science.gov (United States)

    Brandstätter, J.; Kurz, W.; Krenn, K.

    2017-12-01

    Microthermometric analyses of fluid and melt inclusions in hydrothermal veins and in the Cocos Ridge (CCR) basalt were used to reveal the CCR thermal history at IODP Site 344-U1414 and to constrain fluid source and flow. Hydrothermal veins are hosted by lithified sediments and CCR basalt . Site 344-U1414, located 1 km seaward of the Middle American Trench offshore Costa Rica, serves to evaluate fluid/rock interaction, the hydrologic system and geochemical processes linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. The veins in the sedimentary rocks are mainly filled by blocky calcite, containing numerous fluid inclusions, and sometimes crosscut fibrous quartz/chalcedony veins. The veins in the basalt can be differentiated into three types: antitaxial fibrous calcite veins, composite veins with fibrous calcite and clay minerals at the vein margins and spherulitic quartz in the center, and syntaxial blocky aragonite veins surrounded by a clay selvage in the uppermost CCR basalt sections. Secondary minerals, clay minerals, fibrous calcite, quartz/chalcedony and pyrite also filled vesicles in the basalt. Fluid inclusions were mainly found in the aragonite veins and rarely in quartz in the composite veins and vesicles. Blocky veins with embedded wall rock fragments appear in the sediments and in the basalt indicate hydraulic fracturing. The occurrence of decrepitated fluid inclusions show high homogenization temperatures up to 400 °C. Decrepitated fluid inclusions are formed by increased internal overpressure, related to isobaric heating. Elongated fluid inclusion planes, arc-like fluid inclusions and low homogenization temperatures indicate subsequent isobaric cooling. The results obtained so far from Raman spectroscopy and microthermometry indicate CO2 inclusions and petrographic observations suggest the presence of silicate melt inclusions in phenocrysts in the basalt (mainly in clinopyroxene and plagioclase

  7. The submarine hydrothermal system of Panarea (Southern Italy: biogeochemical processes at the thermal fluids - sea bottom interface

    Directory of Open Access Journals (Sweden)

    T. Maugeri

    2006-06-01

    Full Text Available Among the submarine hydrothermal systems located offshore the volcanic archipelago of the Aeolian Islands (Southern Italy, the most active is located off the coasts of Panarea island. Thermal waters, gases and sulfur deposits coexist at the sea bottom where hydrothermal fluids are released from both shallow and deep vents. The chemical and isotopic composition of the fluid phase shows the presence of a significant magmatic component and the physico-chemical conditions of the geothermal reservoir allow the release of reduced chemical species that are microbially mediated towards the production of organic carbon as a form of biochemical energy. Microorganisms inhabiting this environment possess nutritional requirements and overall metabolic pathways ideally suited to such ecosystem that represents a clear example of the close connection between geosphere and biosphere. Microscopic examination of the white mat attached to rock surfaces showed the presence of Thiothrix-like filamentous bacteria. Moderately thermophilic heterotrophic isolates were identified as strains of the genus Bacillus. Although the hydrothermal system of Panarea has to be considered a “shallow” system, it shows many characteristics that make it similar to the “deep” oceanic systems, giving a unique opportunity for improving our knowledge on such an unexplored world by working at this easily accessible site.

  8. Volcano-Hydrothermal Systems of the Kuril Island Arc (Russia): Geochemistry of the Thermal Waters and Gases.

    Science.gov (United States)

    Kalacheva, E.; Taran, Y.; Voloshina, E.; Kotenko, T.; Tarasov, K.

    2017-12-01

    More than 30 active volcanoes with historical eruptions are known on 20 main islands composing the Kuril Arc. Eight islands - Paramushir, Shiashkotan, Rasshua, Ushishir, Ketoy, Urup, Iturup and Kunashir - are characterized by hydrothermal activity, complementary to the fumarole activity in the craters and volcano slopes. At Paramushir, Shiashkotan, Iturup and Kunashir most of thermal manifestations are acidic to ultra-acidic hot springs associated with hydrothermal aquifers inside volcano edifices. The most powerful of them is the ultra-acid hydrothermal system of Ebeko volcano (Paramushir island) with more than 80 t/day of the chloride output and pH of springs of 1.5. At the summit part of the Ebeko volcano there are 12 thermal fields with the total thermal area exceeding 1 km2. The measured temperatures of fumaroles are from 98º C to 500ºC. Another type of hydrothermal activity are the wide spread coastal hot and neutral springs situated as a rule within the tide zone. Four groups of this type of thermal manifestation were found on the western shore of Shiashkotan island. It have Na-Ca-Cl-SO4 composition with temperatures 50-80°C and TDS 7-8 g/L. Coastal neutral springs were found also on Russhua, Uturup and Kunashir islands. Ushishir volcano-hydrothermal system in the middle of the arc is formed by the absorption of magmatic gases by seawater. In the crater of the Pallas cone (Ketoy island) there is a small Glazok lake with acid SO4 water and pH=2.4, TDS=2g/L, T=12oC. Ketoy volcano on the same island hosts a high temperature hydrothermal system with unusual boiling Ca-Na-SO4 neutral springs and steam vents. Mendeleev and Golovnin volcanoes on Kunashir Island are the southernmost of the Kuril arc. Mendeleev edifice is a centre of a large thermal area with many manifestations of different types including steam vents, acid springs and neutral coastal springs. In a 4.2x4 km wide caldera of Golovnin volcano there are two lakes with acid Cl-SO4 water and numerous

  9. Fully determined scaling laws for volumetrically heated convective systems, a tool for assessing habitability of exoplanets

    Science.gov (United States)

    Vilella, Kenny; Kaminski, Edouard

    2017-05-01

    The long-term habitability of a planet rises from its ability to generate and maintain an atmosphere through partial melting and volcanism. This question has been mainly addressed in the framework of plate tectonics, which may be too specific to apply to the wide range of internal dynamics expected for exoplanets, and even to the thermal evolution of the early Earth. Here we propose a more general theoretical approach of convection to build a regime diagram giving the conditions for partial melting to occur, in planetary bodies, as a function of key parameters that can be estimated for exoplanets, their size and internal heating rate. To that aim, we introduce a refined view of the Thermal Boundary Layer (TBL) in a convective system heated from within, that focuses on the temperature and thickness of the TBL at the top of the hottest temperature profiles, along which partial melting shall first occur. This ;Hottest Thermal Boundary Layer; (HotTBL) is first characterized using fully theoretical scaling laws based on the dynamics of thermal boundary layers. These laws are the first ones proposed in the literature that do not rely on empirical determinations of dimensionless constants and that apply to both low Rayleigh and high Rayleigh convective regimes. We show that the scaling laws can be successfully applied to planetary bodies by comparing their predictions to full numerical simulations of the Moon. We then use the scaling laws to build a regime diagram for exoplanets. Combined with estimates of internal heating in exoplanets, the regime diagram predicts that in the habitable zone partial melting occurs in planets younger than the Earth.

  10. Experimental analysis on a novel solar collector system achieved by supercritical CO2 natural convection

    International Nuclear Information System (INIS)

    Chen, Lin; Zhang, Xin-Rong

    2014-01-01

    Highlights: • Supercritical CO 2 flow is proposed for natural circulation solar water heater system. • Experimental system established and consists of supercritical fluid high pressure side and water side. • Stable supercritical CO 2 natural convective flow is well induced and water heating process achieved. • Seasonal solar collector system efficiency above 60% achieved and optimization discussed. - Abstract: Solar collector has become a hot topic both in scientific research and engineering applications. Among the various applications, the hot water supply demand accounts for a large part of social energy consumption and has become one promising field. The present study deals with a novel solar thermal conversion and water heater system achieved by supercritical CO 2 natural circulation. Experimental systems are established and tested in Zhejiang Province (around N 30.0°, E 120.6°) of southeast China. The current system is designed to operate in the supercritical region, thus the system can be compactly made and achieve smooth high rate natural convective flow. During the tests, supercritical CO 2 pipe flow with Reynolds number higher than 6700 is found. The CO 2 fluid temperature in the heat exchanger can be as high as 80 °C and a stable supply of hot water above 45 °C is achieved. In the seasonal tests, relative high collector efficiency generally above 60.0% is obtained. Thermal and performance analysis is carried out with the experiment data. Comparisons between the present system and previous solar water heaters are also made in this paper

  11. Modeling and simulation of the power demand and supply of a hydrothermal power generating system

    International Nuclear Information System (INIS)

    Pronini, R.A.

    1996-01-01

    Security of supply of electric energy is measured by the capacity to cover the energy demand and power of a supply grid. This coverage is important because the winter peak load period in Switzerland will become problematical in the near future. The objective of this research project is to analyze the ability of a power generating system to satisfy the power requirements of the corresponding supply network. The behaviour of the energy system in critical cases (loss of the largest generator, lack of available power from an external supplier or reduced capacity for energy storage) is tested for the present situation and for the rise in the annual load. The simulation of the load of the supply network is carried out by using a model developed for this project. This model is based on the analysis of half-hourly changes of load and on the statistical maximum values. The power generating system consists of nuclear generating units, hydro units with large reservoirs, run of the river installations and imported energy. Standby units such as gas turbines, spot market and coal-fired power stations are also available. Stochastic and deterministic energy and power models have been developed for the various power stations of the hydrothermal power system. In the case of nuclear power stations, a model has been developed on the basis of the output level, production losses and time and length of outages. The possible feeder streams of the run of the river installations and of the hydro units with a large reservoir are simulated using stochastic methods based on the historical values of the last 35 years. The commitment of the hydro units depends on the peak load requirements. The load and capacity over a period of several days and weeks have been simulated with stochastic models based on the Monte Carlo method and constantly (by half hour intervals) compared. In this manner each month can be simulated. (author) figs., tabs., 46 refs

  12. Characterizing the dynamics of hydrothermal systems with muon tomography: the case of La Soufrière de Guadeloupe

    Science.gov (United States)

    Rosas-Carbajal, M.; Marteau, J.; Tramontini, M.; de Bremond d Ars, J.; Le Gonidec, Y.; Carlus, B.; Ianigro, J. C.; Deroussi, S.; Komorowski, J. C.; Gibert, D.

    2017-12-01

    Muon imaging has recently emerged as a powerful method to complement standard geophysical tools in the study of the Earth's subsurface. Muon measurements yield a radiography of the average density along the muon path, allowing to image large volumes of a geological body from a single observation point. Long-term measurements allow to infer density changes by tracking the associated variations in the muon flux. In the context of volcanic hydrothermal systems, this approach helps to characterize zones of steam formation, condensation, water infiltration and storage. We present results of imaging the La Soufrière de Guadeloupe dome and shallow active hydrothermal system with a network of muon telescopes viewing the dome from different positions around its base. First, we jointly invert the muon radiographies of the different telescopes with gravity data to obtain a three-dimensional density model of the lava dome. The model reveals an extended low density region where the hydrothermal system is most active. We then analyze the dynamics of the hydrothermal system from long-term measurements (more than 2 years of almost non-interrupted acquisition) with 5 simultaneous muon telescopes. We identify a periodicity of 1-2 months in the density increase/decrease in the most active zones below fumaroles and acid boiling ponds. Our simultaneous-muon telescope strategy provides constraints on the three-dimensional location of the density changes and an improved quantification of the associated mass flux changes. We compare the temporal trends acquired by the different muon telescopes to time-series of rainfall on the summit recharge area as well as to ground temperature profiles in the vicinity of thermal anomalies and high-discharge summit fumaroles.

  13. Impact of different parameterization schemes on simulation of mesoscale convective system over south-east India

    Science.gov (United States)

    Madhulatha, A.; Rajeevan, M.

    2018-02-01

    Main objective of the present paper is to examine the role of various parameterization schemes in simulating the evolution of mesoscale convective system (MCS) occurred over south-east India. Using the Weather Research and Forecasting (WRF) model, numerical experiments are conducted by considering various planetary boundary layer, microphysics, and cumulus parameterization schemes. Performances of different schemes are evaluated by examining boundary layer, reflectivity, and precipitation features of MCS using ground-based and satellite observations. Among various physical parameterization schemes, Mellor-Yamada-Janjic (MYJ) boundary layer scheme is able to produce deep boundary layer height by simulating warm temperatures necessary for storm initiation; Thompson (THM) microphysics scheme is capable to simulate the reflectivity by reasonable distribution of different hydrometeors during various stages of system; Betts-Miller-Janjic (BMJ) cumulus scheme is able to capture the precipitation by proper representation of convective instability associated with MCS. Present analysis suggests that MYJ, a local turbulent kinetic energy boundary layer scheme, which accounts strong vertical mixing; THM, a six-class hybrid moment microphysics scheme, which considers number concentration along with mixing ratio of rain hydrometeors; and BMJ, a closure cumulus scheme, which adjusts thermodynamic profiles based on climatological profiles might have contributed for better performance of respective model simulations. Numerical simulation carried out using the above combination of schemes is able to capture storm initiation, propagation, surface variations, thermodynamic structure, and precipitation features reasonably well. This study clearly demonstrates that the simulation of MCS characteristics is highly sensitive to the choice of parameterization schemes.

  14. Subseafloor fluid mixing and fossilized microbial life in a Cretaceous 'Lost City'-type hydrothermal system at the Iberian Margin

    Science.gov (United States)

    Klein, F.; Humphris, S. E.; Guo, W.; Schubotz, F.; Schwarzenbach, E. M.; Orsi, W.

    2015-12-01

    Subseafloor mixing of reduced hydrothermal fluids with seawater is believed to provide the energy and substrates needed to support autotrophic microorganisms in the hydrated oceanic mantle (serpentinite). Despite the potentially significant implications for the distribution of microbial life on Earth and other water-bearing planetary bodies, our understanding of such environments remains elusive. In the present study we examined fossilized microbial communities and fluid mixing processes in the subseafloor of a Cretaceous 'Lost City'-type hydrothermal system at the passive Iberia Margin (ODP Leg 149, Hole 897D). Brucite and calcite co-precipitated from mixed fluids ca. 65m below the Cretaceous palaeo-seafloor at temperatures of 32±4°C within steep chemical gradients (fO2, pH, CH4, SO4, ΣCO2, etc) between weathered, carbonate-rich serpentinite breccia and serpentinite. Mixing of oxidized seawater and strongly reducing hydrothermal fluid at moderate temperatures created conditions capable of supporting microbial activity within the oceanic basement. Dense microbial colonies are fossilized in brucite-calcite veins that are strongly enriched in organic carbon but depleted in 13C. We detected a combination of bacterial diether lipid biomarkers, archaeol and archaeal tetraethers analogous to those found in brucite-carbonate chimneys at the active Lost City hydrothermal field. The exposure of mantle rocks to seawater during the breakup of Pangaea fueled chemolithoautotrophic microbial communities at the Iberia Margin during the Cretaceous, possibly before the onset of seafloor spreading in the Atlantic. 'Lost City'-type serpentinization systems have been discovered at mid-ocean ridges, in forearc settings of subduction zones and at continental margins. It appears that, wherever they occur, they can support microbial life, even in deep subseafloor environments as demonstrated in the present study. Because equivalent systems have likely existed throughout most of Earth

  15. Experimental investigation of the influence of the air jet trajectory on convective heat transfer in buildings equipped with air-based and radiant cooling systems

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per; Jensen, Rasmus Lund

    2015-01-01

    -state and dynamic conditions. With the air-based cooling system, a dependency of the convective heat transfer on the air jet trajectory has been observed. New correlations have been developed, introducing a modified Archimedes number to account for the air flow pattern. The accuracy of the new correlations has been...... evaluated to±15%. Besides the study with an air-based cooling system, the convective heat transfer with a radiant cooling system has also been investigated. The convective flow at the activated surface is mainly driven by natural convection. For other surfaces, the complexity of the flow and the large......The complexity and diversity of airflow in buildings make the accurate definition of convective heat transfer coefficients (CHTCs) difficult. In a full-scale test facility, the convective heat transfer of two cooling systems (active chilled beam and radiant wall) has been investigated under steady...

  16. On the role of ice-nucleating aerosol in the formation of ice particles in tropical mesoscale convective systems

    Science.gov (United States)

    Ladino, Luis A.; Korolev, Alexei; Heckman, Ivan; Wolde, Mengistu; Fridlind, Ann M.; Ackerman, Andrew S.

    2018-01-01

    Over decades, the cloud physics community has debated the nature and role of aerosol particles in ice initiation. The present study shows that the measured concentration of ice crystals in tropical mesoscale convective systems exceeds the concentration of ice nucleating particles (INPs) by several orders of magnitude. The concentration of INPs was assessed from the measured aerosol particles concentration in the size range of 0.5 to 1 µm. The observations from this study suggest that primary ice crystals formed on INPs make only a minor contribution to the total concentration of ice crystals in tropical mesoscale convective systems. This is found by comparing the predicted INP number concentrations with in-situ ice particle number concentrations. The obtained measurements suggest that ice multiplication is the likely explanation for the observed high concentrations of ice crystals in this type of convective system. PMID:29551842

  17. A Gigantic Jet Observed Over an Mesoscale Convective System in Midlatitude Region

    Science.gov (United States)

    Yang, Jing; Sato, Mitsuteru; Liu, Ningyu; Lu, Gaopeng; Wang, Yu; Wang, Zhichao

    2018-01-01

    Gigantic jets (GJs) are mostly observed over summer tropical or tropical-like thunderstorms. This study reports observation of a GJ over a mesoscale convective system (MCS) in the midlatitude region in eastern China. The GJ is observed over a relatively weak radar reflectivity region ahead of the leading line, and the maximum radar echo top along the GJ azimuth was lower than the tropopause in the same region, significantly different from past studies that indicate summer GJs are usually associated with convective surges or overshooting tops. Also different from most of previous observations showing GJ-producing summer thunderstorms only produced GJ type of transient luminous events during their life cycles, two sprites were also captured in a time window of 15 min containing the GJ, indicating that the MCS provides favorable conditions not only for the GJ but also for the sprites. The balloon-borne soundings of the MCS show that there were large wind shears in the middle and upper levels of the thundercloud, which may have played important roles for the GJ production.

  18. Convective heat transfer of supercritical CO_2 in a rock fracture for enhanced geothermal systems

    International Nuclear Information System (INIS)

    Zhang, Le; Jiang, Peixue; Wang, Zhenchuan; Xu, Ruina

    2017-01-01

    Highlights: • Contrasting experiments between a rough and a smooth fracture were performed. • A numerical model of rough fracture was reconstructed based on CT scanning data. • Heat transfer in rough fracture was affected by channeling and disturbance effects. - Abstract: Convective heat transfer characteristics of supercritical pressure fluid in a rock fracture are important for building an accurate heat transfer model of enhanced geothermal systems. This paper presents experimental investigations of laminar convection heat transfer of supercritical pressure CO_2 in an artificial smooth parallel-plate fracture and a rough and tortuous fracture that was created using the Brazilian technique. Hot rock with a relatively high initial temperature reserves more heat, which can ensure a larger heat extraction rate for a longer time when cold fluid flows through the fracture. Compared with the smooth parallel-plate fracture, CO_2 flowing through the rough and tortuous fracture with an equivalent hydraulic aperture extracted less heat from the hot rock due to the less efficient heat exchange in a rough fracture caused by channeling effect. This was illustrated by numerical simulation results of the reconstructed fracture based on micro-computed tomography scan data. The overall Nusselt number obtained from the numerical results was larger in a rough fracture with a larger Reynolds number due to disturbance effect on the boundary layer development. The heat transfer performance in a rough fracture is therefore influenced by interactions of the channeling and disturbance effects caused by the tortuous flow path.

  19. Carbon dioxide diffuse emission and thermal energy release from hydrothermal systems at Copahue-Caviahue Volcanic Complex (Argentina)

    Science.gov (United States)

    Chiodini, Giovanni; Cardellini, Carlo; Lamberti, María Clara; Agusto, Mariano; Caselli, Alberto; Liccioli, Caterina; Tamburello, Giancarlo; Tassi, Franco; Vaselli, Orlando; Caliro, Stefano

    2015-10-01

    The north-western sector of Caviahue caldera (Argentina), close to the active volcanic system of Copahue, is characterized by the presence of several hydrothermal sites that host numerous fumarolic emissions, anomalous soil diffuse degassing of CO2 and hot soils. In March 2014, measurements of soil CO2 fluxes in 5 of these sites (namely, Las Máquinas, Las Maquinitas I, Las Maquinitas II, Anfiteatro, and Termas de Copahue) allowed an estimation that 165 t of deeply derived CO2 is daily released. The gas source is likely related to a relatively shallow geothermal reservoir containing a single vapor phase as also suggested by both the geochemical data from the 3 deep wells drilled in the 1980s and gas geoindicators applied to the fumarolic discharges. Gas equilibria within the H-C-O gas system indicate the presence of a large, probably unique, single phase vapor zone at 200-210 °C feeding the hydrothermal manifestations of Las Máquinas, Las Maquinitas I and II and Termas de Copahue. A natural thermal release of 107 MW was computed by using CO2 as a tracer of the original vapor phase. The magmatic signature of the incondensable fumarolic gases, the wide expanse of the hydrothermal areas and the remarkable high amount of gas and heat released by fluid expulsion seem to be compatible with an active magmatic intrusion beneath this portion of the Caviahue caldera.

  20. Three-dimensional electrical resistivity model of the hydrothermal system in Long Valley Caldera, California, from magnetotellurics

    Science.gov (United States)

    Peacock, Jared R.; Mangan, Margaret T.; McPhee, Darcy K.; Wannamaker, Phil E.

    2016-01-01

    Though shallow flow of hydrothermal fluids in Long Valley Caldera, California, has been well studied, neither the hydrothermal source reservoir nor heat source has been well characterized. Here a grid of magnetotelluric data were collected around the Long Valley volcanic system and modeled in 3-D. The preferred electrical resistivity model suggests that the source reservoir is a narrow east-west elongated body 4 km below the west moat. The heat source could be a zone of 2–5% partial melt 8 km below Deer Mountain. Additionally, a collection of hypersaline fluids, not connected to the shallow hydrothermal system, is found 3 km below the medial graben, which could originate from a zone of 5–10% partial melt 8 km below the south moat. Below Mammoth Mountain is a 3 km thick isolated body containing fluids and gases originating from an 8 km deep zone of 5–10% basaltic partial melt.

  1. Fluid mixing and the deep biosphere of a fossil Lost City-type hydrothermal system at the Iberia Margin.

    Science.gov (United States)

    Klein, Frieder; Humphris, Susan E; Guo, Weifu; Schubotz, Florence; Schwarzenbach, Esther M; Orsi, William D

    2015-09-29

    Subseafloor mixing of reduced hydrothermal fluids with seawater is believed to provide the energy and substrates needed to support deep chemolithoautotrophic life in the hydrated oceanic mantle (i.e., serpentinite). However, geosphere-biosphere interactions in serpentinite-hosted subseafloor mixing zones remain poorly constrained. Here we examine fossil microbial communities and fluid mixing processes in the subseafloor of a Cretaceous Lost City-type hydrothermal system at the magma-poor passive Iberia Margin (Ocean Drilling Program Leg 149, Hole 897D). Brucite-calcite mineral assemblages precipitated from mixed fluids ca. 65 m below the Cretaceous paleo-seafloor at temperatures of 31.7 ± 4.3 °C within steep chemical gradients between weathered, carbonate-rich serpentinite breccia and serpentinite. Mixing of oxidized seawater and strongly reducing hydrothermal fluid at moderate temperatures created conditions capable of supporting microbial activity. Dense microbial colonies are fossilized in brucite-calcite veins that are strongly enriched in organic carbon (up to 0.5 wt.% of the total carbon) but depleted in (13)C (δ(13)C(TOC) = -19.4‰). We detected a combination of bacterial diether lipid biomarkers, archaeol, and archaeal tetraethers analogous to those found in carbonate chimneys at the active Lost City hydrothermal field. The exposure of mantle rocks to seawater during the breakup of Pangaea fueled chemolithoautotrophic microbial communities at the Iberia Margin, possibly before the onset of seafloor spreading. Lost City-type serpentinization systems have been discovered at midocean ridges, in forearc settings of subduction zones, and at continental margins. It appears that, wherever they occur, they can support microbial life, even in deep subseafloor environments.

  2. Radon surveys and monitoring at active volcanoes: an open window on deep hydrothermal systems and their dynamics

    Science.gov (United States)

    Cigolini, Corrado; Laiolo, Marco; Coppola, Diego

    2017-04-01

    The behavior of fluids in hydrothermal systems is critical in volcano monitoring and geothermal prospecting. Analyzing the time series of radon emissions on active volcanoes is strategic for detecting and interpreting precursory signals of changes in volcanic activity, eventually leading to eruptions. Radon is a radioactive gas generated from the decay of U bearing rocks, soils and magmas. Although radon has been regarded as a potential precursor of earthquakes, radon anomalies appear to be better suited to forecast volcanic eruptions since we know where paroxysms may occur and we can follow the evolution of volcanic activity. Radon mapping at active volcanoes is also a reliable tool to assess diffuse and concentrated degassing as well as efficiently detecting earthquake-volcano interactions. Systematic radon monitoring has been shown to be a key factor for evaluating the rise of volcanic and hydrothermal fluids. In fact, the decay properties of radon, the duration of radon anomalies together with sampling rates may be cross-checked with the chemistry of hydrothermal fluids (and their transport properties) to constrain fluids ascent rates and to infer the permeability and porosity of rocks in sectors surrounding the active conduits. We hereby further discuss the data of radon surveys and monitoring at Somma-Vesuvius, Stromboli and La Soufrière (Guadeloupe, Lesser Antilles). The integrated analysis of seismic and geochemical data, including radon emissions, may be successfully used in testing temperature distributions and variations of porosity and permeability in volcanic hydrothermal systems and can be used as a proxy to analyze geothermal reservoirs.

  3. Hydrothermal conversion of FAU zeolite into RUT zeolite in TMAOH system

    OpenAIRE

    Jon, Hery; Takahashi, Shoutarou; Sasaki, Hitoshi; Oumi, Yasunori; Sano, Tsuneji

    2008-01-01

    The highly crystalline and pure RUT (RUB-10) zeolite could be obtained from the hydrothermal conversion of FAU zeolite used as a crystalline Si/Al source in tetramethylammonium hydroxide (TMAOH) media. As compared to amorphous silica/Al(OH)3 and amorphous silica/γ-Al2O3 sources, the crystallization rate for the formation of RUT zeolite was clearly faster when FAU zeolite was employed as the Si/Al source. Moreover, it was found that the hydrothermal conversion of FAU zeolite into RUT zeolite d...

  4. The response of a simulated Mesoscale Convective System to increased aerosol pollution

    Science.gov (United States)

    Clavner, Michal

    This work focuses on the impacts of aerosols on the total precipitation amount, rates and spatial distribution of precipitation produced by a Mesoscale Convective System (MCS), as well as the characteristics of a derecho event. Past studies have shown that the impacts on MCS-produced precipitation to changes in aerosol concentration are strongly dependent on environmental conditions, primarily humidity and environmental wind shear. Changes in aerosol concentrations were found to alter MCS-precipitation production directly by modifying precipitation processes and indirectly by affecting the efficiency of the storm's self-propagation. Observational and numerical studies have been conducted that have examined the dynamics responsible for the generation of widespread convectively-induced windstorms, primarily focusing on environmental conditions and the MCS features that generate a derecho event. While the sensitivity of the formation of bow-echoes, the radar signature associated with derecho events, to changes in microphysics has been examined, a study on a derecho-producing MCS characteristics to aerosol concentrations has not. In this study different aerosol concentrations and their effects on precipitation and a derecho produced by an MCS are examined by simulating the 8 May 2009 "Super-Derecho" MCS. The MCS was simulated using the Regional Atmospheric Modeling System (RAMS), a cloud-resolving model (CRM) with sophisticated aerosol and microphysical parameterizations. Three simulations were conducted that varied in their initial aerosol concentration, distribution and hygroscopicity as determined by their emission sources. The first simulation contained aerosols from only natural sources and the second with aerosols sourced from both natural and anthropogenic emissions The third simulation contained the same aerosol distribution as in the second simulation, however multiplied by a factor of 5 in order to represent a highly polluted scenario. In all three of the

  5. Geochemistry of the hydrothermal systems in the Jujuy Province, Argentina, and relationship with the regional geology

    Science.gov (United States)

    Peralta Arnold, Yesica; Cabassi, Jacopo; Tassi, Franco; Caffe, Pablo; Vaselli, Orlando

    2016-04-01

    The western sector of the Jujuy province (22°-24° S), Argentina, basically consisting of the Puna region (from 3,500 to 4,700 m a.s.l.) that borders the Central Volcanic Zone (CVZ), is characterized by sub-meridional ridges that alternate with elongated basins and by extremely voluminous intermediate and silicic ignimbrite deposits, the latter being related to late miocenic and pliocenic calderas and central volcanic edifices. In this region, several hydrothermal discharges with outlet temperatures up to 62°C occur. Among them, the Coranzulí and Pairique thermal emissions show a spatial relationship with miocenic volcanic complexes, whereas other thermal manifestations (Queñual, Orosmayo, Pirquitas, Arizutar, Cono Panizo and Rachaite) are clearly controlled by the local structural setting. Most of these thermal waters have relatively high total dissolved solids (TDS up to 46,500 mg/L), an alkaline-chloride composition and significant concentrations of B, NH4 and SiO2, i.e. they show the typical geochemical features of geothermal brine. Exceptions are the Coranzulí, Orosmayo and Rachaite springs, mainly fed by a shallow Na(Ca)-bicarbonate aquifer. The eastern sector of the province consists of the Eastern Cordillera, composed of a proterozoic basement constituted by the sedimentary sequences of the Puncoviscana Fm, and the Subandean Range, which shows wide east-vergence anticlines whose detachment levels are Silurian-Devonian shales. Both regions are separated by a major thrust that rises the Proterozoic and Eopaleozoic sequences over the Subandean System. The thermal waters in the Eastern Cordillera, namely Termas de Reyes, are characterized by alkaline-sulfate composition, temperature of ≈50°C and neutral pH. In contrast, in the Subandean Ranges, which is separated from the Eastern Cordillera by a thrust rising Proterozoic and Eopaleozoic sequences over the Subandean System, the Aguas Calientes springs are characterized by low temperature (from 21°C to

  6. Newly discovered hydrothermal system on the Alarcón Rise, Mexico

    Science.gov (United States)

    Paduan, J. B.; Clague, D. A.; Caress, D. W.; Lundsten, L.; Martin, J. F.; Nieves-Cardoso, C.

    2012-12-01

    The Alarcón Rise lies at the mouth of the Gulf of California, and is the last segment of the East Pacific Rise before the plate boundary redirects into the gulf. As part of MBARI's expedition to the gulf in 2012, the neovolcanic zone of the entire ridge segment was mapped by MBARI's mapping AUV. 110 potential hydrothermal chimneys were identified in the new high resolution maps, and 70 were visited with the ROV Doc Ricketts, after having been sought in vain without the maps on an expedition in 2003. Two active vent fields were found, and have been named Meyibó and Ja sít from local native languages. They lie 2.5km apart at ~2300m depth, and are associated with a large, young sheet flow 1/3 of the way along the ridge from the south, on the most inflated part of the ridge. The southern field, Meyibó, contains 14 active chimneys (confirmed with ROV observations) nestled in grabens of several highly fractured cones surrounded by the sheet flow, and generally aligned with its discontinuous, 8km-long fissure system. The northern field, Ja sít, is a broad cluster of 8 active chimneys (also confirmed) rising above the sheet flow's channel system, more than 150m from the fissure. The chimneys stand as tall as 18 m. The most vigorous vent "black smoke" (mineral-rich fluid) >300°C and others are bathed in "white smoke". The active chimneys are populated with bacterial mat and dense clumps of Riftia pachyptila with tubes as long as 1.5m. Abundant limpets, Bythograea thermydron and galatheid crabs, and the pink vent fish Thermarces cerberus were on and near the giant tube worms. Alvinellid worms were observed at 2 chimneys. Some cracks in nearby lava flows vented clear fluid and were populated with tubeworms or Calyptogena magnifica clams. Several chimneys exhibited signs of waning activity: dead tubeworms were still attached and only a minor portion of the edifice supported bacterial mat and live tubeworms. Inactive chimneys are more numerous (48 were confirmed with ROV

  7. Discovery of Fracture Networks in the Basal Part of Modern Hydrothermal System in Okinawa Tough, SW Japan

    Science.gov (United States)

    Saito, S.; Yamada, Y.; Sanada, Y.; Kido, Y. N.; Hamada, Y.; Shiraishi, K.; Hsiung, K. H.; Tsuji, T.; Eng, C.; Maeda, L.; Kumagai, H.; Nozaki, T.; Ishibashi, J. I.

    2017-12-01

    A scientific drilling expedition, CK16-01 was conducted by D/V Chikyu in an active hydrothermal field on the Iheya-North Knoll in Okinawa Trough in February-March, 2016 as a part of "Next-generation Technology for Ocean Resources Survey" of the Cross-ministerial Strategic Innovation Promotion Program (SIP). During the expedition logging while drilling (LWD) was deployed to uncover the architecture of modern hydrothermal deposits near the seafloor. A downhole sequence of fracture network (stock-work) was discovered by high resolution resistivity images at Site C9023 in the southern part of the knoll. More than 500 structural features were extracted from the borehole images down to 188 meter below the seafloor. Quantitative image analyses were performed and three types of conductive fractures were identified and classified as Generation 1 (G1), Generation 2 (G2), and Generation 3 (G3) based on the crossing or cutting relationship. The average thickness of fractures decrease with generation from G1 (78 mm), G2 (57 mm), to G3 (45 mm). G1 is developed in the entire interval, whereas G2 and G3 are commonly observed in the intervals of lower gamma ray and high resistivity ( 10 ohm-m) at 77-125 m and 167-186 m where sulfide minerals hosted in silicified rocks were observed in recovered core samples. Low angle fractures (<30°) are typically developed in the interval at 120 -125 m, suggesting possible lateral hydrothermal conduits. The quantitative analysis of fracture network based on borehole images shows the detailed formation process of stock-work in the basal part of modern hydrothermal system.

  8. Geochemical characterisation of Taal volcano-hydrothermal system and temporal evolution during continued phases of unrest (1991-2017)

    Science.gov (United States)

    Maussen, Katharine; Villacorte, Edgardo; Rebadulla, Ryan R.; Maximo, Raymond Patrick; Debaille, Vinciane; Bornas, Ma. Antonia; Bernard, Alain

    2018-02-01

    Taal volcano (Luzon Island, Philippines) has last erupted in 1977 but has known some periods of increased activity, characterised by seismic swarms, ground deformation, increased carbon dioxide flux and in some cases temperature anomalies and the opening of fissures. We studied major, trace element and sulphur and strontium isotopic composition of Taal lake waters and hot springs over a period of 25 years to investigate the geochemical evolution of Taal volcano's hydrothermal system and its response to volcanic unrest. Long-term evolution of Main Crater Lake (MCL) composition shows a slow but consistent decrease of acidity, SO4, Mg, Fe and Al concentrations and a trend from light to heavy sulphate, consistent with a general decrease of volcanic gases dissolving in the hydrothermal system. Na, K and Cl concentrations remain constant indicating a non-volcanic origin for these elements. Sulphate and strontium isotopic data suggest this neutral chloride-rich component represents input of geothermal water into Taal hydrothermal system. A significant deviation from the long-term baseline can be seen in two samples from 1995. That year, pH dropped from 2.6 to 2.2, F, Si and Fe concentrations increased and Na, K and Cl concentrations decreased. Sulphate was depleted in 34S and temperature was 4 °C above baseline level at the time of sampling. We attribute these changes to the shallow intrusion of a degassing magma body during the unrest in 1991-1994. More recent unrest periods have not caused significant changes in the geochemistry of Taal hydrothermal waters and are therefore unlikely to have been triggered by shallow magma intrusion. A more likely cause for these events is thus pressurisation of the hydrothermal reservoir by increasing degassing from a stagnant magma reservoir. Our study indicates that new magmatic intrusions that might lead to the next eruption of Taal volcano are expected to change the geochemistry of MCL in the same way as in 1994-1995, with the most

  9. Spatio-temporal distributions of meso convective systems in NE China and its vicinity

    Science.gov (United States)

    Yuan, Meiying; Li, Zechun; Zhang, Xiaoling; Li, Xun

    2008-08-01

    Based on the IR cloud imagery from the Chinese FY-2C satellite for June ~ August, 2005 - 2007, statistics is undertaken of meso convective systems (MCS) over NE China and its neighborhood, obtaining the space - time distributions of MCS. MCS include elliptical type( MCC's) , persistent elongated type (PECS's), in shape. Dividing the total MCS into MαMCS, MβMCS and MCC (PECS) . Results show that the number of meso-α MCS (dominantly PECS's) is considerably more than that of meso-β MCS (largely MCCss), which are observed mainly in the NE China plain and Daxing'an Mountains, especially in the entrance to the plain as well as its central ~ northern portion; the MCS occur mainly in June ~ August, particularly in June; the extratropical MCS show two peak phases, one being in 1500-2200 BST the other being 0000-0700 BST as the secondary peaking interval.

  10. Surface properties, more than size, limiting convective distribution of virus-sized particles and viruses in the central nervous system.

    Science.gov (United States)

    Chen, Michael Y; Hoffer, Alan; Morrison, Paul F; Hamilton, John F; Hughes, Jeffrey; Schlageter, Kurt S; Lee, Jeongwu; Kelly, Brandon R; Oldfield, Edward H

    2005-08-01

    Achieving distribution of gene-carrying vectors is a major barrier to the clinical application of gene therapy. Because of the blood-brain barrier, the distribution of genetic vectors to the central nervous system (CNS) is even more challenging than delivery to other tissues. Direct intraparenchymal microinfusion, a minimally invasive technique, uses bulk flow (convection) to distribute suspensions of macromolecules widely through the extracellular space (convection-enhanced delivery [CED]). Although acute injection into solid tissue is often used for delivery of oligonucleotides, viruses, and liposomes, and there is preliminary evidence that certain of these large particles can spread through the interstitial space of the brain by the use of convection, the use of CED for distribution of viruses in the brain has not been systematically examined. That is the goal of this study. Investigators used a rodent model to examine the influence of size, osmolarity of buffering solutions, and surface coating on the volumetric distribution of virus-sized nanoparticles and viruses (adeno-associated viruses and adenoviruses) in the gray matter of the brain. The results demonstrate that channels in the extracellular space of gray matter in the brain are large enough to accommodate virus-sized particles and that the surface characteristics are critical determinants for distribution of viruses in the brain by convection. These results indicate that convective distribution can be used to distribute therapeutic viral vectors in the CNS.

  11. SI-Hydro: an information system for the Brazilian hydrothermal system; SI-Hidro: um sistema de informacao para o sistema hidrotermico brasileiro

    Energy Technology Data Exchange (ETDEWEB)

    Fontanini, Walcir

    1995-03-01

    An information system for the Brazilian hydrothermal system denominated SI-Hydro is presented. This information system supplies data on the hydroelectric and thermoelectric park and can be used in the main elements recognition and in the planning and management of the whole system. The information system uses the product INGRES in the platform UNIX/X-Windows, which supplies resources so much for access to the database as for the interface man machine through the fourth generation language denominated Windows4GL. The next main topics are presented: information systems concepts and its relation with the direction levels to an organization and implications for the hydrothermal system operation planning in the scenarios of short, medium and long terms; thermal and hydroelectric plants operation routine details; the most used technical terms definition; and mathematical physical typical plants processes modeling presentation.

  12. Numerical Simulations of TRMM LBA, TOGA, COARE, GATE, ARM and PRESTORM Convective Systems: Sensitivity tests on Microphysical Processes

    Science.gov (United States)

    Tao, W.-K.; Wang, Y.; Lang, S.; Ferrier, B.; Simpson, J.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The 3D Goddard Cumulus Ensemble (GCE) model was utilized to examine the behavior and response of simulated deep tropical cloud systems that occurred over the west Pacific warm pool region, the Atlantic ocean and the central United States. The periods chosen for simulation were convectively active periods during TOGA-COARE (February 22 1993, December 11-17, 1992; December 19-28, February 9-13, 1993), GATE (September 4, 1974), LBA (January 26 and February 23, 1998), ARM (1997 IOP) and PRESTORM (June 11, 1985). We will examine differences in the microphysics for both warm rain and ice processes (evaporation /sublimation and condensation/ deposition), Q1 (Temperature), Q2 (Water vapor) and Q3 (momentum both U and V) budgets for these three convective events from different large-scale environments. The contribution of stratiform precipitation and its relationship to the vertical shear of the large-scale horizontal wind will also be examined. New improvements to the GCE model (i.e., microphysics: 4ICE two moments and 3ICE one moment; advection schemes) as well as their sensitivity to the model results will be discussed. Preliminary results indicated that various microphysical schemes could have a major impact on stratiform formation as well as the size of convective systems. However, they do not change the major characteristics of the convective systems, such as: arc shape, strong rotational circulation on both ends of system, heavy precipitation along the leading edge of systems.

  13. Variability of mass-size relationships in tropical Mesoscale Convective Systems

    Science.gov (United States)

    Fontaine, Emmanuel; Leroy, Delphine; Delanoë, Julien; Dupuy, Régis; Lilie, Lyle; Strapp, Walter; Protat, Alain; Schwarzenböeck, Alfons

    2015-04-01

    The mass of individual ice hydrometeors in Mesoscale Convective Systems (MCS) has been investigated in the past using different methods in order to retrieve power law type mass-size relationships m(D) with m = α D^β. This study focuses on the variability of mass-size relationships in different types of MCS. Three types of tropical MCS were sampled during different airborne campaigns: (i) continental MCS during the West African monsoon (Megha-Tropique 2010), (ii) oceanic MCS over the Indian Ocean (Megha-Tropique 2011), and (iii) coastal MCS during the North-Australian monsoon (HAIC-HIWC). Mass-size relationships of ice hydrometeors are derived from a combined analysis of particle images from 2D-array probes and associated reflectivity factors measured with a Doppler cloud radar (94GHz) on the same research aircraft. A theoretical study of numerous hydrometeor shapes simulated in 3D and arbitrarily projected on a 2D plan allowed to constrain the exponent β of the m(D) relationship as a function of the derived surface-diameter relationship S(D), which is likewise written as a power law. Since S(D) always can be determined for real data from 2D optical array probes or other particle imagers, the evolution of the m(D) exponent β can be calculated along the flight trajectory. Then the pre-factor α of m(D) is constrained from theoretical simulations of the radar reflectivity factor matching the measured reflectivity factor along the aircraft trajectory. Finally, the Condensed Water Content (CWC) is deduced from measured particle size distributions (PSD) and retrieved m(D) relationships along the flight trajectory. Solely for the HAIC-HIWC campaign (North Australian Monsoon) a bulk reference measurement (IKP instrument) of high CWC could be performed in order to compare with the above described CWC deduced from ice hydrometeor images and reflectivity factors. Both CWC are coherent. Mean profiles of m(D) coefficients, PSD, and CWC are calculated as a function of the

  14. Oxygen isotope mapping and evaluation of paleo-hydrothermal systems associated with synvolcanic intrusion and VMS deposits

    International Nuclear Information System (INIS)

    Taylor, B.E

    2001-01-01

    Whole-rock oxygen isotope mapping provides a useful method for the delineation and quantitative evaluation of paleo-hydrothermal systems associated with syn-volcanic intrusions and volcanic-associated massive sulfide (VMS) deposits. During the course of a four-year study of regional alteration systems associated with VMS Deposits, four syn-volcanic intrusive complexes in Canada were mapped using stable isotope techniques. The complexes included Noranda, Quebec; Clifford-Ben Nevis, Ontario; Snow Lake, Manitoba, and Sturgeon Lake, Ontario. This study was regional in extent, involving large areas and large numbers of whole-rock samples: Noranda (625 km 2 ;≥600 samples, plus others (total = 1198); Sturgeon Lake (525 km 2 ; 452 samples); Clifford-Ben Nevis (160 km 2 ; 251 samples); and Snow Lake (84 km 2 ; 575 samples). Isotopic data on whole-rock carbonates and hydrous minerals were also collected. The regional isotopic studies were carried out in concert with other studies on mineral assemblages and mineral composition, and on associated intrusive and extrusive rocks. The Clifford-Ben Nevis area was selected as a control area, in as much as it contains no known VMS deposits; all other areas are well-known, productive VMS districts. Oxygen isotope maps are, in a sense, thermal maps, illustrating the paleo-distribution of heat and fluids, and offering a potential aid to exploration. The isotopic data may be contoured to reveal zones of 18 O depletion and enrichment, relative to unaltered rocks. Zones of δ 18 O≤60% comprise rocks that have reacted with seawater at high (e.g., 300+ o C) temperatures. The volume of foot-wall rocks isotopically-depleted by water/rock interaction during the life of one or more episodes of submarine hydrothermal activity is proportional to the amount of heat available from the syn-volcanic intrusive center. These altered rocks comprise the reaction zone often inferred to have supplied metals and other constituents for the VMS deposits

  15. Validation of system codes RELAP5 and SPECTRA for natural convection boiling in narrow channels

    Energy Technology Data Exchange (ETDEWEB)

    Stempniewicz, M.M., E-mail: stempniewicz@nrg.eu; Slootman, M.L.F.; Wiersema, H.T.

    2016-10-15

    Highlights: • Computer codes RELAP5/Mod3.3 and SPECTRA 3.61 validated for boiling in narrow channels. • Validated codes can be used for LOCA analyses in research reactors. • Code validation based on natural convection boiling in narrow channels experiments. - Abstract: Safety analyses of LOCA scenarios in nuclear power plants are performed with so called thermal–hydraulic system codes, such as RELAP5. Such codes are validated for typical fuel geometries applied in nuclear power plants. The question considered by this article is if the codes can be applied for LOCA analyses in research reactors, in particular exceeding CHF in very narrow channels. In order to answer this question, validation calculations were performed with two thermal–hydraulic system codes: RELAP and SPECTRA. The validation was based on natural convection boiling in narrow channels experiments, performed by Prof. Monde et al. in the years 1990–2000. In total 42 vertical tube and annulus experiments were simulated with both codes. A good agreement of the calculated values with the measured data was observed. The main conclusions are: • The computer codes RELAP5/Mod 3.3 (US NRC version) and SPECTRA 3.61 have been validated for natural convection boiling in narrow channels using experiments of Monde. The dimensions applied in the experiments were performed for a range that covers the values observed in typical research reactors. Therefore it is concluded that both codes are validated and can be used for LOCA analyses in research reactors, including natural convection boiling. The applicability range of the present validation is: hydraulic diameters of 1.1 ⩽ D{sub hyd} ⩽ 9.0 mm, heated lengths of 0.1 ⩽ L ⩽ 1.0 m, pressures of 0.10 ⩽ P ⩽ 0.99 MPa. In most calculations the burnout was predicted to occur at lower power than that observed in the experiments. In several cases the burnout was observed at higher power. The overprediction was not larger than 16% in RELAP and 15% in

  16. Hydration of the lower stratosphere by ice crystal geysers over land convective systems

    Directory of Open Access Journals (Sweden)

    S. Khaykin

    2009-03-01

    Full Text Available The possible impact of deep convective overshooting over land has been explored by six simultaneous soundings of water vapour, particles and ozone in the lower stratosphere next to Mesoscale Convective Systems (MCSs during the monsoon season over West Africa in Niamey, Niger in August 2006. The water vapour measurements were carried out using a fast response FLASH-B Lyman-alpha hygrometer. The high vertical resolution observations of the instrument show the presence of accumulation of enhanced water vapour layers between the tropopause at 370 K and the 420 K level. Most of these moist layers are shown connected with overshooting events occurring upwind as identified from satellite IR images over which the air mass probed by the sondes passed during the three previous days. In the case of a local overshoot identified by echo top turrets above the tropopause by the MIT C-band radar also in Niamey, tight coincidence was found between enhanced water vapour, ice crystal and ozone dip layers indicative of fast uplift of tropospheric air across the tropopause. The water vapour mixing ratio in the enriched layers exceeds frequently by 1–3 ppmv the average 6 ppmv saturation ratio at the tropopause and by up to 7 ppmv in the extreme case of local storm in coincidence with the presence of ice crystals. The presence of such layers strongly suggests hydration of the lower stratosphere by geyser-like injection of ice particles over overshooting turrets. The pile-like increase of water vapour up to 19 km seen by the high-resolution hygrometer during the season of maximum temperature of the tropopause, suggests that the above hydration mechanism may contribute to the summer maximum moisture in the lower stratosphere. If this interpretation is correct, hydration by ice geysers across the tropopause might be an important contributor to the stratospheric water vapour budget.

  17. Visualization of Two Phase Natural Convection Flow in a Vertical Pipe using the Sulfuric Acid - Copper Sulfate Electroplating System

    Energy Technology Data Exchange (ETDEWEB)

    Ohk, Seung-Min; Chae, Myeong-Seon; Chung, Bum-Jin [Kyung Hee Univ., Yongin (Korea, Republic of)

    2014-10-15

    The passive containment cooling system (PCCS) driven by natural forces convection gain draws research interests after Fukushima NPP accident. The PCCS was classified into three categories: Containment pressure suppression, Containment passive heat removal/pressure suppression systems and Passive containment spray. Among the types of containment passive heat removal/pressure suppression systems, the system composed of an internal heat exchanger and an external coolant tank is considered. In a severe accident condition, the heat from the containment atmosphere is transferred to the outer surface of the heat exchanger by the convection and condensation of the mixture of steam and gases. On the other hand, the heat is transferred to external pool by single phase or two phase natural convection inside of heat exchanger pipes. The study aimed at investigating the influence of the diameter (D) and height (H) of the heat exchanger pipes on the single phase and two phase natural convection heat transfer. As the initial stage of the study, the two phase natural convection flow inside a vertical pipe is visualized. In order to achieve the aim with ample test rig, a sulfuric acid - cooper sulfate electroplating system was employed based on the analogy between heat and mass transfer. The reduction of hydrogen ion at the cathode surface at high potential was used to simulate the boiling phenomena. This study tried to visualize the boiling heat transfer inside a vertical pipe using a cupric acid-copper sulfate (H{sub 2}SO{sub 4}-CuSO{sub 4}) electroplating system. This seems to be successful so far. However further study has to be done to compare the result with real two phase flow situation. The surface tension and surface characteristics are to be tuned to simulate the real situation.

  18. Cultivation-Independent and Cultivation-Dependent Analysis of Microbes in the Shallow-Sea Hydrothermal System Off Kueishantao Island, Taiwan: Unmasking Heterotrophic Bacterial Diversity and Functional Capacity.

    Science.gov (United States)

    Tang, Kai; Zhang, Yao; Lin, Dan; Han, Yu; Chen, Chen-Tung A; Wang, Deli; Lin, Yu-Shih; Sun, Jia; Zheng, Qiang; Jiao, Nianzhi

    2018-01-01

    Shallow-sea hydrothermal systems experience continuous fluctuations of physicochemical conditions due to seawater influx which generates variable habitats, affecting the phylogenetic composition and metabolic potential of microbial communities. Until recently, studies of submarine hydrothermal communities have focused primarily on chemolithoautotrophic organisms, however, there have been limited studies on heterotrophic bacteria. Here, fluorescence in situ hybridization, high throughput 16S rRNA gene amplicon sequencing, and functional metagenomes were used to assess microbial communities from the shallow-sea hydrothermal system off Kueishantao Island, Taiwan. The results showed that the shallow-sea hydrothermal system harbored not only autotrophic bacteria but abundant heterotrophic bacteria. The potential for marker genes sulfur oxidation and carbon fixation were detected in the metagenome datasets, suggesting a role for sulfur and carbon cycling in the shallow-sea hydrothermal system. Furthermore, the presence of diverse genes that encode transporters, glycoside hydrolases, and peptidase indicates the genetic potential for heterotrophic utilization of organic substrates. A total of 408 cultivable heterotrophic bacteria were isolated, in which the taxonomic families typically associated with oligotrophy, copiotrophy, and phototrophy were frequently found. The cultivation-independent and -dependent analyses performed herein show that Alphaproteobacteria and Gammaproteobacteria represent the dominant heterotrophs in the investigated shallow-sea hydrothermal system. Genomic and physiological characterization of a novel strain P5 obtained in this study, belonging to the genus Rhodovulum within Alphaproteobacteria, provides an example of heterotrophic bacteria with major functional capacity presented in the metagenome datasets. Collectively, in addition to autotrophic bacteria, the shallow-sea hydrothermal system also harbors many heterotrophic bacteria with versatile

  19. The 2012-2014 eruptive cycle of Copahue Volcano, Southern Andes. Magmatic-Hydrothermal system interaction and manifestations.

    Science.gov (United States)

    Morales, Sergio; Alarcón, Alex; Basualto, Daniel; Bengoa, Cintia; Bertín, Daniel; Cardona, Carlos; Córdova, Maria; Franco, Luis; Gil, Fernando; Hernandez, Erasmo; Lara, Luis; Lazo, Jonathan; Mardones, Cristian; Medina, Roxana; Peña, Paola; Quijada, Jonathan; San Martín, Juan; Valderrama, Oscar

    2015-04-01

    Copahue Volcano (COPV), in Southern Andes of Chile, is an andesitic-basaltic stratovolcano, which is located on the western margin of Caviahue Caldera. The COPV have a NE-trending fissure with 9 aligned vents, being El Agrio the main currently active vent, with ca. 400 m in diameter. The COPV is placed into an extensive hydrothermal system which has modulated its recent 2012-2014 eruptive activity, with small phreatic to phreatomagmatic eruptions and isolated weak strombolian episodes and formation of crater lakes inside the main crater. Since 2012, the Southern Andes Volcano Observatory (OVDAS) carried out the real-time monitoring with seismic broadband stations, GPS, infrasound sensors and webcams. In this work, we report pre, sin, and post-eruptive seismic activity of the last two main eruptions (Dec, 2012 and Oct, 2014) both with different seismic precursors and superficial activity, showing the second one a particularly appearance of seismic quiescence episodes preceding explosive activity, as an indicator of interaction between magmatic-hydrothermal systems. The first episode, in late 2012, was characterized by a low frequency (0.3-0.4 Hz and 1.0-1.5 Hz) continuous tremor which increased gradually from background noise level amplitude to values of reduced displacement (DR), close to 50 cm2 at the peak of the eruption, reaching an eruptive column of ~1.5 km height. After few months of recording low energy seismicity, a sequence of low frequency, repetitive and low energy seismic events arose, with a frequency of occurrence up to 300 events/hour. Also, the VLP earthquakes were added to the record probably associated with magma intrusion into a deep magmatic chamber during all stages of eruptive process, joined to the record of VT seismicity during the same period, which is located throughout the Caviahue Caldera area. Both kind of seismic patterns were again recorded in October 2014, being the precursor of the new eruptive cycle at this time as well as the

  20. Study of Hydrothermal Particulate Matter from a Shallow Venting System, offshore Nayarit, Mexico

    Science.gov (United States)

    Ortega-Osorio, A.; Prol-Ledesma, R. M.; Reyes, A. G.; Rubio-Ramos, M. A.; Torres-Vera, M. A.

    2001-12-01

    A shallow (30 ft) hydrothermal site named ``Cora'' (after the indigenous people thereby) was surveyed and sampled throughout direct observation with SCUBA diving during November 25 to December 4, 2000. A total of 10 dives were conducted in order to obtain representative samples from an 85oC fluid source of approximately 10 cm in diameter. Inherent difficulties to the sampling, such as poor visibility and strong bottom currents were overcome and samples of hydrothermal fluid, gas, rocks, and particulate matter were collected directly from the vent. Water samples and hydrothermal fluid were taken with a homemade 1 l cylindrical bottles of two lines by flushing in from the bottom for about ten minutes until total displacement of the seawater; similar procedure was carried out for gas samples. Particulate matter was collected with 0.4mm polycarbonate membrane filters and preserved in a desiccators at a fridge temperature until analysis onshore. Preliminary description of the rock samples suggest that pyritization is the main mineralisation process. Filters containing hydrothermal particulate matter were surveyed under the scanning electron microscope in order to identify the nature (inorganic and organic), as well as the chemistry of the particles. SEM examination revealed the presence of particles of different kind that suggests high degree of mixing and re-suspension: Planctonic organisms and organic matter appeared to be abundant; 25 micron particles of different carbonate faces and inorganic particles of silicates were also recognized. Distinctive euhedral colloidal grains were identified as the resulting process of precipitation from the solution. Microanalysis of iron and sulfur content of 10 micron particles indicate a very likely sulphide mineral face (greigite); 8 micron cinnabar particles are consistent with the mineralization conditions, observed as well in the inner walls of the vent. Analyses of dissolved and particulate trace metals are still ongoing at

  1. Natural convection liquid desiccant loop as an auxiliary air conditioning system: investigating the operational parameters

    Science.gov (United States)

    Fazilati, Mohammad Ali; Alemrajabi, Ali Akbar; Sedaghat, Ahmad

    2018-03-01

    Liquid desiccant air conditioning system with natural convection was presented previously as a new generation of AC systems. The system consists of two three-fluid energy exchangers namely absorber and regenerator in which the action of air dehumidifying and desiccant regeneration is done, respectively. The influence of working parameters on system performance including the heat source and heat sink temperature, concentration of desiccant solution fills the system initially and humidity content of inlet air to regenerator is investigated experimentally. The heat source temperatures of 50 °C and 60 °C, heat sink temperatures of 15 °C and 20 °C and desiccant concentrations of 30% and 34%, are examined here. The inlet air to regenerator has temperature of 38.5 °C and three relative humidity of 14%, 38% and 44%. In all experiments, the inlet air to absorber has temperature of 31 °C and relative humidity of 75%. By inspecting evaluation indexes of system, it is revealed that higher startup desiccant concentration solution is more beneficial for all study cases. It is also observed although the highest/lowest temperature heat source/heat sink is most suitable for best system operation, increasing the heat source temperature should be accompanied with decreasing heat sink temperature. Using drier air stream for regenerator inlet does not necessarily improve system performance; and the air stream with proper value of humidity content should be employed. Finally after running the system in its best working condition, the coefficient of performance (COP) reached 4.66 which verified to be higher than when the same air conditioning task done by a conventional vapor compression system, in which case the COP was 3.38.

  2. The interplay of evolved seawater and magmatic-hydrothermal fluids in the 3.24 Ga panorama volcanic-hosted massive sulfide hydrothermal system, North Pilbara Craton, Western Australia

    Science.gov (United States)

    Drieberg, Susan L.; Hagemann, Steffen G.; Huston, David L.; Landis, Gary; Ryan, Chris G.; Van Achterbergh, Esmé; Vennemann, Torsten

    2013-01-01

    The ~3240 Ma Panorama volcanic-hosted massive sulfide (VHMS) district is unusual for its high degree of exposure and low degree of postdepositional modification. In addition to typical seafloor VHMS deposits, this district contains greisen- and vein-hosted Mo-Cu-Zn-Sn mineral occurrences that are contemporaneous with VHMS orebodies and are hosted by the Strelley granite complex, which also drove VHMS circulation. Hence the Panorama district is a natural laboratory to investigate the role of magmatic-hydrothermal fluids in VHMS hydrothermal systems. Regional and proximal high-temperature alteration zones in volcanic rocks underlying the VHMS deposits are dominated by chlorite-quartz ± albite assemblages, with lesser low-temperature sericite-quartz ± K-feldspar assemblages. These assemblages are typical of VHMS hydrothermal systems. In contrast, the alteration assemblages associated with granite-hosted greisens and veins include quartz-topaz-muscovite-fluorite and quartz-muscovite (sericite)-chlorite-ankerite. These vein systems generally do not extend into the overlying volcanic pile. Fluid inclusion and stable isotope studies suggest that the greisens were produced by high-temperature (~590°C), high-salinity (38–56 wt % NaCl equiv) fluids with high densities (>1.3 g/cm3) and high δ18O (9.3 ± 0.6‰). These fluids are compatible with the measured characteristics of magmatic fluids evolved from the Strelley granite complex. In contrast, fluids in the volcanic pile (including the VHMS ore-forming fluids) were of lower temperature (90°–270°C), lower salinity (5.0–11.2 wt % NaCl equiv), with lower densities (0.88–1.01 g/cm3) and lower δ18O (−0.8 ± 2.6‰). These fluids are compatible with evolved Paleoarchean seawater. Fluids that formed the quartz-chalcopyrite-sphalerite-cassiterite veins, which are present within the granite complex near the contact with the volcanic pile, were intermediate in temperature and isotopic composition between the greisen

  3. Moisture Sources and Life Cycle of Convective Systems over Western Colombia

    Directory of Open Access Journals (Sweden)

    Meiry Sayuri Sakamoto

    2011-01-01

    Full Text Available This paper describes life cycle and moisture sources of mesoscale convective systems (MCSs observed over western Colombia. Results show that, in general, MCS are more frequent during boreal summer and autumn, and particularly, systems observed in summer season present longer life and larger extension. On the continent, MCS genesis is strongly affected by sea breeze and diurnal heating and presents a peak from 15 to 18 LST. For oceanic systems, the main genesis period is later, from 00 to 03 LST. Continental and oceanic systems present a tendency of westward displacement. Analysis using a Lagrangian approach implemented to estimate air parcel trajectories suggests that, during boreal winter, the main moisture sources are from the Caribbean Sea and tropical north Atlantic, possibly resulting from the moisture-laden trade winds and the land-ocean temperature contrast over northern South America. In summer, it is clear the influence of ITCZ positioning with moisture particles traveling from the tropical Atlantic over Amazonian river basin. In Autumn, Chilean-Peruvian Pacific is the main moisture source, confirming the importance of Chocó low level jet to MCS genesis.

  4. Did a whole-crustal hydrothermal system generate the Irish Zn-Pb orefield?

    Science.gov (United States)

    Daly, J. Stephen; Badenszki, Eszter; Chew, David; Kronz, Andreas; O'Rourke, Helen; Whitehouse, Martin; Menuge, Julian; van den Berg, Riana

    2016-04-01

    Current models[1] for the genesis of the giant Irish Carboniferous-hosted Zn-Pb orefield propose shallow (700°C) metamorphism and melting during the Acadian orogeny at ~390Ma and during separate episodes of extension at ~ 381-373Ma and ~362Ma. Sm-Nd garnet dating shows that the lower crust remained hot or was re-heated to ~600°C at ~341Ma during Lower Carboniferous volcanism, also associated with extension and, in part, coincident with the mineralization[1]. Isotopic data from the xenoliths correspond closely to Sr and Nd isotopic analyses of gangue calcite[8] and galena Pb[9] isotopic data from the major ore deposits. While Zn contents of the xenoliths permit them to be metal sources, their mineralogy and texture provide an enriched template and a plausible extraction mechanism. In situ analyses of modally-abundant biotite and garnet show significant enrichment in Zn (and other relevant metals) as well as order of magnitude depletion of Zn during retrograde alteration, providing a metal-release mechanism and pointing to a hydrothermal fluid system operating at least to depths of ~ 25km. References [1] Wilkinson, J.J. & Hitzman, M.W. 2015. The Irish Pb-Zn orefield: The view from 2014. In: Archibald, S.M. and Piercey, S.J. (eds) Current Perspectives on Zinc deposits. Irish Association for Economic Geology, pp. 59-72.; [2] Davidheiser-Kroll, B., Stuart, F.M. & Boyce, A.J. 2014. Mineralium Deposita, 49, 547-553; [3] Elliott, H. 2015. Unpublished PhD thesis, University of Southampton; [4] Hnatyshin, D., Creaser, R.A., Wilkinson, J.J. & Gleeson, S.A. 2015. Geology, 43, 143-146; [5] McCusker, J. & Reed, C. 2013. Mineralium Deposita, 48, 687-695; [6] Van den Berg, R., Daly, J.S. & Salisbury, M.H. 2005. Tectonophysics, 407(1-2), 81-99; [7] Hauser, F., O'Reilly, B.M., Readman, P.W., Daly, J. S. & Van den Berg, R. 2008. Geophysical Journal International 175, 1254-1272; [8] Walshaw, R.D., Menuge, J.F. & Tyrrell, S. 2006. Mineralium Deposita, 41, 803-819; [9] Everett, C

  5. Experimental investigation of As, Sb and Cs behavior during olivine serpentinization in hydrothermal alkaline systems

    Science.gov (United States)

    Lafay, Romain; Montes-Hernandez, German; Janots, Emilie; Munoz, Manuel; Auzende, Anne Line; Gehin, Antoine; Chiriac, Rodica; Proux, Olivier

    2016-04-01

    While Fluid-Mobile Elements (FMEs) such as B, Sb, Li, As or Cs are particularly concentrated in serpentinites, data on FME fluid-serpentine partitioning, distribution, and sequestration mechanisms are missing. In the present experimental study, the behavior of Sb, As and Cs during San Carlos olivine serpentinization was investigated using accurate mineralogical, geochemical, and spectroscopic characterization. Static-batch experiments were conducted at 200 °C, under saturated vapor pressure (≈1.6 MPa), for initial olivine grain sizes of coefficient increasing such as CsDp/fl = 1.5-1.6 elements are however substantially different. While the As partition coefficient remains constant throughout the serpentinization reaction, the Cs partition coefficient decreases abruptly in the first stages of the reaction to reach a constant value after the reaction is 40-60% complete. Both As and Cs partitioning appear to decrease with increasing initial olivine grain size, but there is no significant difference in the partitioning coefficient between the 30-56 and 56-150 μm grain size after complete serpentinization. X-ray absorption spectroscopy (XAS) measurements combined with X-ray chemical measurements reveal that the As(V) is mainly adsorbed onto the serpentinization products, especially brucite. In contrast, mineralogical characterization combined with XAS spectroscopy reveal redox sensitivity for Sb sequestration within serpentine products, depending on the progress of the reaction. When serpentinization is coefficient compared to that of the serpentine and brucite assemblage. Antimony reduction appears linked to water reduction accompanying the bulk iron oxidation, as half the initial Fe(II) is oxidized into Fe(III) and incorporated into the serpentine products once the reaction is over. The reduction of Sb implies a decrease of its solubility, but the type of secondary Sb-rich phases identified here might not be representative of natural systems where Sb

  6. Development of a system code with CFD capability for analyzing turbulent mixed convection in gas-cooled reactors

    International Nuclear Information System (INIS)

    Kim, Hyeon Il

    2010-02-01

    In order to demonstrate the accuracy of predictions in a turbulent mixed convection regime in which both inertia and buoyancy force compete with each other, we found out that assessments done using a single-dimensional system code with a recently updated heat transfer package have shown that this approach cannot give a reasonable prediction of the wall temperature in a case involving strong heating, where the regime falls into turbulent mixed convection regime. It has been known that the main reason of this deficiency comes from the degraded heat transfer in turbulent mixed convection regime, which is below that of convective heat transfer during turbulent forced convection. We investigated two mechanisms that cause this deterioration in convective heat transfer influenced by buoyancy: (1) modification of turbulence, also known as the direct (structural) effect, through the buoyancy-induced production of turbulent kinetic energy: and (2) an indirect (external) effect that occurs through modification of the mean flow. We investigated the Launder-Sharma model of turbulence whether it can appropriately represent the mechanisms causing the degraded heat transfer in Computational Fluid Dynamics (CFD). We found out that this model can capture low Re effects such that a non-equilibrium turbulent boundary layer in turbulent mixed convection regime can be resolved. The model was verified and validated extensively initially with the commercial CFD code, Fluent with a user application package known as the User Defined Function (UDF). The results from this implementation were compared to a set of data that included (1) an experimental data commonly accepted as a standardized problem to verify a turbulent flow, (2) the results from a Direct Numerical Simulation (DNS) in a turbulent forced and mixed convection regime, (3) empirical correlations regarding the friction coefficient and the non-dimensional heat transfer coefficient, the Nusselt number for a turbulent forced

  7. S/Se ratio of pyrite from eastern Australian VHMS deposits: implication of magmatic input into volcanogenic hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Huston, D L [Geological Survey of Canada, Ottawa, ON (Canada); Sie, S H; Suter, G F [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience; Cooke, D R [Tasmania Univ., Sandy Bay, TAS (Australia)

    1994-12-31

    The proton microprobe was used to determine the concentrations of over twenty trace elements in pyrite grains from four volcanic-hosted massive sulphide (VHMS) deposits in eastern Australia. Of the elements determined, Se has the most potential in resolving important problems in the genesis of this class of ore deposits. This paper summarises analytical conditions, describes the distribution of Se in pyrite in VHMS deposits as determined in this and other studies, discusses the speciation of Se in hydrothermal fluids, and presents a genetic model on the relative contribution of magmatic versus sea water Se (and S) in VHMS systems. 2 refs., 1 fig.

  8. S/Se ratio of pyrite from eastern Australian VHMS deposits: implication of magmatic input into volcanogenic hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Huston, D.L. [Geological Survey of Canada, Ottawa, ON (Canada); Sie, S.H.; Suter, G.F. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience; Cooke, D.R. [Tasmania Univ., Sandy Bay, TAS (Australia)

    1993-12-31

    The proton microprobe was used to determine the concentrations of over twenty trace elements in pyrite grains from four volcanic-hosted massive sulphide (VHMS) deposits in eastern Australia. Of the elements determined, Se has the most potential in resolving important problems in the genesis of this class of ore deposits. This paper summarises analytical conditions, describes the distribution of Se in pyrite in VHMS deposits as determined in this and other studies, discusses the speciation of Se in hydrothermal fluids, and presents a genetic model on the relative contribution of magmatic versus sea water Se (and S) in VHMS systems. 2 refs., 1 fig.

  9. Modeling and analysis of a robust thermal control system based on forced convection thermal switches

    Science.gov (United States)

    Williams, Andrew D.; Palo, Scott E.

    2006-05-01

    There is a critical need, not just in the Department of Defense (DOD) but the entire space industry, to reduce the development time and overall cost of satellite missions. To that end, the DOD is actively pursuing the capability to reduce the deployment time of a new system from years to weeks or even days. The goal is to provide the advantages space affords not just to the strategic planner but also to the battlefield commanders. One of the most challenging aspects of this problem is the satellite's thermal control system (TCS). Traditionally the TCS must be vigorously designed, analyzed, tested, and optimized from the ground up for every satellite mission. This "reinvention of the wheel" is costly and time intensive. The next generation satellite TCS must be modular and scalable in order to cover a wide range of applications, orbits, and mission requirements. To meet these requirements a robust thermal control system utilizing forced convection thermal switches was investigated. The problem was investigated in two separate stages. The first focused on the overall design of the bus. The second stage focused on the overarching bus architecture and the design impacts of employing a thermal switch based TCS design. For the hot case, the fan provided additional cooling to increase the heat transfer rate of the subsystem. During the cold case, the result was a significant reduction in survival heater power.

  10. Contribution to the operating energy planning of hydrothermal power systems; Contribuicao ao planejamento da operacao energetica de sistemas hidrotermicos de potencia

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Adriano Alber de Franca Mendes

    1991-08-01

    This work treats of the problem of the planning of the energy operation of hydrothermal power systems, gone back to those with predominance of hydraulic generation, as it is the case of the Brazilian system. The work makes an analysis of the problem of the planning of the energy operation of systems hydrothermal leaving of the concepts and nature of this problem. Their inherent difficulties are shown and they come the main approaches in operation in countries with predominance of hydroelectric generation. It still introduces the methodology in energy planning in Brazil being pointed their main limitations. Finally an alternative model for the planning of the energy operation of the system brazilian hydrothermal, based on the made studies is also presented.

  11. Long term planning in the hydro-thermal system - A new generation of tools. Final report; Langtidsplanlegging i hydrotermiske system - En ny generasjon verktoey. Sluttrapport

    Energy Technology Data Exchange (ETDEWEB)

    Gjelsvik, Anders; Haugstad, Arne; Honve, Ingrid; Mo, Birger

    2010-01-15

    The project 'Long term planning in the hydro-thermal system - A new generation of tools' has during the project period 2006 - 2009 led to an upgrade of stochastic models for production planning in hydro-thermal power system. The development has primarily been concentrated on ProdRisk, a model for seasonal and long-term planning in hydropower system based on the Stochastic Dual Dynamic Programming (SDDP). The project has lifted the model a long way towards operational use of seasonal planning of hydropower producers. In addition, the quality of the results from the model, makes it considered a good model also for the analysis of development projects in waterways. The report describes this and other activity within the project. Implementation of the project has contributed both to raise the level of tools used for production planning in the Nordic countries and to increase the competence of participants. (AG)

  12. Experimental Investigation of Convective Heat Transfer during Night Cooling with Different Ventilation Systems and Surface Emissivities

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per; Jensen, Rasmus Lund

    2013-01-01

    models for convection. In a full-scale test room, the heat transfer was investigated during 12 h of discharge by night-time ventilation. A total of 34 experiments have been performed, with different ventilation types (mixing and displacement), air change rates, temperature differences between the inlet...... air and the room, and floor emissivities. This extensive experimental study enabled a detailed analysis of the convective and radiative flow at the different surfaces of the room. The experimentally derived convective heat transfer coefficients (CHTC) have been compared to existing correlations....... For mixing ventilation, existing correlations did not predict accurately the convective heat transfer at the ceiling due to differences in the experimental conditions. But the use of local parameters of the air flow showed interesting results to obtain more adaptive CHTC correlations. For displacement...

  13. Power optimization in the star-LM modular, natural convection reactor system

    International Nuclear Information System (INIS)

    Spencer, B.W.; Sienicki, J.J.; Farmer, M.T.

    2001-01-01

    The secure, transportable, autonomous reactor (STAR) project addresses the needs of developing countries and independent power producers for small, multi-purpose energy systems, which operate near autonomously for very long term. The STAR-LM variant described here is a liquid metal cooled, fast reactor system. Previous development of STAR-LM resulted in a 300 MWt modular, pool-type reactor based on criteria for factory fabrication, full transportability (barge, overland, rail), and fast construction and startup. Steam generator modules are placed directly into the primary heat transport circuit, eliminating the intermediate heat transport loop. Natural convection heat transport at all power levels eliminates the need for main coolant pumps. Seismic isolation eliminates concern about seismic and sloshing-related loads in the pool configuration. Even end-of-spectrum postulated events such as loss-of-heat sink with failure to scram are terminated passively by inherent core power shutdown, and decay heat is passively rejected to the atmospheric air inexhaustible heat sink by guard vessel exterior cooling. Recent concept development has focused on maximizing the power achievable in a small module size based on preserving key criteria for: full spectrum of modes of module transport from factory to site (including rail transport); 100% natural circulation heat transport; ultra-long core cartridge lifetime; coolant and cladding peak temperatures well within the existing (Russian) database for Pb/Bi coolant and ferritic steel core materials. (author)

  14. Simulation of the trajectory of microwaves during passage of Mesoescale Convective System over Southern Brazil

    Science.gov (United States)

    Diniz, F. L.; Munchow, G. B.; Herdies, D. L.; Foster, P. R.

    2010-12-01

    When the eletromagnetic wave travels in the atmosphere from one medium to another with different density and/or composition suffers small changes in speed and direction of propagation. These changes are caused by the vertical variation of atmospheric refractive index. This causes different types of trajectory deviations, which can be called: normal refraction, sub-refraction, super-refraction and duct. The condition to create duct is satisfied when there is a especific vertical profile of refraction, in this case an eletromagnectic wave will oscillate in a layer of the atmosphere. Considering that this ducts condition can causes damage in the transmission and reception of microwave system equipment (e.g. telecomunications, global positioning, weather radars and satellites) and that in the Rio Grande do Sul, state of Brazil, there are two weather radars, this study present a simulation of the trajectory that would have an eletromagnetic wave. In this study was used soundings of the atmosphere to infer the vertical profile of refractive index during the passage of a Mesoescale Convective System on September 7, 2009. In the lack of this data a numerical simulation with nested grids using Weather Research & Forecasting Model was performed to infer this.

  15. Numerical Modeling of the Hydrothermal System at East Pacific Rise 9°50'N Including Anhydrite Precipitation

    Science.gov (United States)

    Kolandaivelu, K. P.; Lowell, R. P.

    2015-12-01

    To better understand the effects of anhydrite precipitation on mid-ocean ridge hydrothermal systems, we conducted 2-D numerical simulations of two-phase hydrothermal circulation in a NaCl-H2O fluid at the East Pacific Rise 9°50'N. The simulations were constrained by key observational thermal data and seismicity that suggests the fluid flow is primarily along axis with recharge focused into a small zone near a 4th order discontinuity. The simulations considered an open-top square box with a fixed seafloor pressure of 25 MPa, and nominal seafloor temperature of 10 °C. The sides of the box were assumed to be impermeable and insulated. We considered two models: a homogeneous model with a permeability of 10-13 m2 and a heterogeneous model in which layer 2A extrusives were given a higher permeability. Both models had a fixed bottom temperature distribution and initial porosity of 0.1. Assuming that anhydrite precipitation resulted from the decrease in solubility with increasing temperature as downwelling fluid gets heated, we calculated the rate of porosity decrease and sealing times in each cell at certain time snapshots in the simulations. The results showed that sealing would occur most rapidly in limited regions near the base of the high-temperature plumes, where complete sealing could occur on decadal time scales. Though more detailed analysis is needed, it appeared that the areas of rapid sealing would likely have negligible impact on the overall circulation pattern and hydrothermal vent temperatures. The simulations also indicated that sealing due to anhydrite precipitation would occur more slowly at the margins of the ascending plumes. The sealing times in the deep recharge zone determined in these simulations were considerably greater than estimated from 1D analytical calculations, suggesting that with a 2D model, focused recharge at the EPR 9°50'N site may occur, at least on a decadal time scale.

  16. Diagnosing the average spatio-temporal impact of convective systems – Part 1: A methodology for evaluating climate models

    Directory of Open Access Journals (Sweden)

    M. S. Johnston

    2013-12-01

    Full Text Available An earlier method to determine the mean response of upper-tropospheric water to localised deep convective systems (DC systems is improved and applied to the EC-Earth climate model. Following Zelinka and Hartmann (2009, several fields related to moist processes and radiation from various satellites are composited with respect to the local maxima in rain rate to determine their spatio-temporal evolution with deep convection in the central Pacific Ocean. Major improvements to the earlier study are the isolation of DC systems in time so as to prevent multiple sampling of the same event, and a revised definition of the mean background state that allows for better characterisation of the DC-system-induced anomalies. The observed DC systems in this study propagate westward at ~4 m s−1. Both the upper-tropospheric relative humidity and the outgoing longwave radiation are substantially perturbed over a broad horizontal extent and for periods >30 h. The cloud fraction anomaly is fairly constant with height but small maximum can be seen around 200 hPa. The cloud ice water content anomaly is mostly confined to pressures greater than 150 hPa and reaches its maximum around 450 hPa, a few hours after the peak convection. Consistent with the large increase in upper-tropospheric cloud ice water content, albedo increases dramatically and persists about 30 h after peak convection. Applying the compositing technique to EC-Earth allows an assessment of the model representation of DC systems. The model captures the large-scale responses, most notably for outgoing longwave radiation, but there are a number of important differences. DC systems appear to propagate eastward in the model, suggesting a strong link to Kelvin waves instead of equatorial Rossby waves. The diurnal cycle in the model is more pronounced and appears to trigger new convection further to the west each time. Finally, the modelled ice water content anomaly peaks at pressures greater than 500 h

  17. Ca isotope fractionation and Sr/Ca partitioning associated with anhydrite formation at mid-ocean ridge hydrothermal systems: An experimental approach

    Science.gov (United States)

    Syverson, D. D.; Scheuermann, P.; Pester, N. J.; Higgins, J. A.; Seyfried, W. E., Jr.

    2016-12-01

    The elemental and isotopic mass balance of Ca and Sr between seawater and basalt at mid-ocean ridge (MOR) hydrothermal systems is an integrated reflection of the various physiochemical processes, which induce chemical exchange, in the subseafloor. Specifically, the processes of anhydrite precipitation and recrystallization are recognized to be important controls on governing the Ca and Sr elemental and isotope compositions of high temperature vent fluids, however, few experimental data exist to constrain these geochemical effects. Thus, to better understand the associated Sr/Ca partitioning and Ca isotope fractionation and rate of exchange between anhydrite and dissolved constituents, anhydrite precipitation and recrystallization experiments were performed at 175, 250, and 350°C and 500 bar at chemical conditions indicative of active MOR hydrothermal systems. The experimental data suggest that upon entrainment of seawater into MOR hydrothermal systems, anhydrite will precipitate rapidly and discriminate against the heavy isotopes of Ca (Δ44/40Ca(Anh-Fluid) = -0.68 - -0.25 ‰), whereas Sr/Ca partitioning depends on the saturation state of the evolving hydrothermal fluid with respect to anhydrite at each PTX (KD(Anh-Fluid) = 1.24 - 0.55). Coupling experimental constraints with the temperature gradient inferred for high temperature MOR hydrothermal systems in the oceanic crust, data suggest that the Ca isotope and Sr elemental composition of anhydrite formed near the seafloor will be influenced by disequilibrium effects, while, at higher temperatures further into the oceanic crust, anhydrite will be representative of equilibrium Sr/Ca partitioning and Ca isotope fractionation conditions. These experimental observations are consistent with analyzed Sr/Ca and Ca isotope compositions of anhydrites and vent fluids sampled from modern MOR hydrothermal systems1,2 and can be used to further constrain the geochemical effects of hydrothermal circulation in the oceanic crust

  18. Comparative assessment of five potential sites for magma: hydrothermal systems - geophysics

    Energy Technology Data Exchange (ETDEWEB)

    Kasameyer, P.

    1980-09-02

    As part of a comparative assessment for the Continental Scientific Drilling Program, geophysical data were used, to characterize and evaluate potential magma-hydrothermal targets at five drill sites in the western United States. The sites include Roosevelt Hot Springs, Utah, the Rio Grande Rift, New Mexico, and The Geysers-Clear Lake, Long Valley, and Salton Trough areas, California. This summary discusses the size, depth, temperature, and setting of each potential target, as well as relvant scientific questions about their natures and the certainty of their existence.

  19. Retrievals of Ice Cloud Microphysical Properties of Deep Convective Systems using Radar Measurements

    Science.gov (United States)

    Tian, J.; Dong, X.; Xi, B.; Wang, J.; Homeyer, C. R.

    2015-12-01

    This study presents innovative algorithms for retrieving ice cloud microphysical properties of Deep Convective Systems (DCSs) using Next-Generation Radar (NEXRAD) reflectivity and newly derived empirical relationships from aircraft in situ measurements in Wang et al. (2015) during the Midlatitude Continental Convective Clouds Experiment (MC3E). With composite gridded NEXRAD radar reflectivity, four-dimensional (space-time) ice cloud microphysical properties of DCSs are retrieved, which is not possible from either in situ sampling at a single altitude or from vertical pointing radar measurements. For this study, aircraft in situ measurements provide the best-estimated ice cloud microphysical properties for validating the radar retrievals. Two statistical comparisons between retrieved and aircraft in situ measured ice microphysical properties are conducted from six selected cases during MC3E. For the temporal-averaged method, the averaged ice water content (IWC) and median mass diameter (Dm) from aircraft in situ measurements are 0.50 g m-3 and 1.51 mm, while the retrievals from radar reflectivity have negative biases of 0.12 g m-3 (24%) and 0.02 mm (1.3%) with correlations of 0.71 and 0.48, respectively. For the spatial-averaged method, the IWC retrievals are closer to the aircraft results (0.51 vs. 0.47 g m-3) with a positive bias of 8.5%, whereas the Dm retrievals are larger than the aircraft results (1.65 mm vs. 1.51 mm) with a positive bias of 9.3%. The retrieved IWCs decrease from ~0.6 g m-3 at 5 km to ~0.15 g m-3 at 13 km, and Dm values decrease from ~2 mm to ~0.7 mm at the same levels. In general, the aircraft in situ measured IWC and Dm values at each level are within one standard derivation of retrieved properties. Good agreements between microphysical properties measured from aircraft and retrieved from radar reflectivity measurements indicate the reasonable accuracy of our retrievals.

  20. Role of upper-level wind shear on the structure and maintenance of derecho-producing convective systems

    Science.gov (United States)

    Coniglio, Michael Charles

    Common large-scale environments associated with the development of derecho-producing convective systems from a large number of events are identified using statistical clustering of the 500-mb geopotential heights as guidance. The majority of the events (72%) fall into three main patterns that include a well-defined upstream trough (40%), a ridge (20%), and a zonal, low-amplitude flow (12%), which is defined as an additional warm-season pattern that is not identified in past studies of derecho environments. Through an analysis of proximity soundings, discrepancies are found in both low-level and deep-tropospheric shear parameters between observations and the shear profiles considered favorable for strong, long-lived convective systems in idealized simulations. To explore the role of upper-level shear in derecho environments, a set of two-dimensional simulations of density currents within a dry, neutrally stable environment are used to examine the ability of a cold pool to lift environmental air within a vertically sheared flow. The results confirm that the addition of upper-level shear to a wind profile with weak to moderate low-level shear increases the vertical displacement of low-level parcels despite a decrease in the vertical velocity along the cold pool interface, as suggested by previous studies. Parcels that are elevated above the surface (1-2 km) overturn and are responsible for the deep lifting in the deep-shear environments. This deep overturning caused by the upper-level shear helps to maintain the tilt of the convective systems in more complex two-dimensional and three dimensional simulations. The overturning also is shown to greatly increase the size of the convective systems in the three-dimensional simulations by facilitating the initiation and maintenance of convective cells along the cold pool. When combined with estimates of the cold pool motion and the storm-relative hodograph, these results may best be used for the prediction of the demise of

  1. A simulation of the hydrothermal response to the Chesapeake Bay bolide impact

    Science.gov (United States)

    Sanford, W.E.

    2005-01-01

    Groundwater more saline than seawater has been discovered in the tsunami breccia of the Chesapeake Bay impact Crater. One hypothesis for the origin of this brine is that it may be a liquid residual following steam separation in a hydrothermal system that evolved following the impact. Initial scoping calculations have demonstrated that it is feasible such a residual brine could have remained in the crater for the 35 million years since impact. Numerical simulations have been conducted using the code HYDROTHERM to test whether or not conditions were suitable in the millennia following the impact for the development of a steam phase in the hydrothermal system. Hydraulic and thermal parameters were estimated for the bedrock underlying the crater and the tsunami breccia that fills the crater. Simulations at three different breccia permeabilities suggest that the type of hydrothermal system that might have developed would have been very sensitive to the permeability. A relatively low breccia permeability (1 ?? 10-16 m2) results in a system partitioned into a shallow water phase and a deeper superheated steam phase. A moderate breccia permeability (1 ?? 10-15 m2 ) results in a system with regionally extensive multiphase conditions. A relatively high breccia permeability (1 ?? 10-14 m2 ) results in a system dominated by warm-water convection cells. The permeability of the crater breccia could have had any of these values at given depths and times during the hydrothermal system evolution as the sediments compacted. The simulations were not able to take into account transient permeability conditions, or equations of state that account for the salt content of seawater. Results suggest, however, that it is likely that steam conditions existed at some time in the system following impact, providing additional evidence that is consistent with a hydrothermal origin for the crater brine. ?? Blackwell Publishing Ltd.

  2. Automated Tracking of Tornado-Producing Mesoscale Convective Systems in the United States

    Science.gov (United States)

    Kuo, K.; Hong, Y.; Clune, T. L.

    2011-12-01

    The great majority of Earth Science events are studied using "snap-shot" observations in time, mainly due to the scarcity of observations with dense temporal coverage and the lack of robust methods amenable to connecting the "snap shots". To enable the studies of these events in the four-dimensional (4D) spatiotemporal space and to demonstrate the utility of this capability, we have applied the neighbor enclosed area tracking (NEAT) method of Inatsu (2009) to three years of high-resolution (in both time and space) NEXRAD-derived and rain-gauge-corrected QE2 precipitation observations and GOES satellite Rapid Scan Operation imagery to track tornado-producing mesoscale convective systems (MCS's). We combine information from the databases of the Tornado History Project (which provides tornado occurrence and trajectory) and the NWS Watch/Warning Archive (which provides severe weather watch/warning locations) to obtain initial estimate of the time and location of a tornado-producing MCS. The NEAT algorithm is then applied to QE2 and GOES data, both forward and backward in time, to identify the entire system as one integral entity from its inception to its eventual dissipation in the 4D spatiotemporal space. For each system so identified, we extract its morphological/structural parameters, such as perimeter length, area, and orientation, from each of the snap shots in time. We also record physical parameters such as minimum and maximum precipitation rates. In addition, we perform areal integral on the precipitation rate field, which in turn enables time integral for the entire MCS throughout its lifecycle to obtain an estimate of the system's precipitation production. We can extend this proof-of-concept prototype to other precipitation producing severe weather events, such as blizzards. Furthermore, the spatiotemporal data collected may be used to discover other data, such as satellite remote sensing observations and model analyses/simulations, which can then be combined

  3. Controls on water vapor isotopes over Roorkee, India: Impact of convective activities and depression systems

    Science.gov (United States)

    Saranya, P.; Krishan, Gopal; Rao, M. S.; Kumar, Sudhir; Kumar, Bhishm

    2018-02-01

    The study evaluates the water vapor isotopic compositions and its controls with special reference to Indian Summer Monsoon (ISM) season at Roorkee, India. Precipitation is usually a discrete event spatially and temporally in this part of the country, therefore, the information provided is limited, while, the vapors have all time availability and have a significant contribution in the hydrological cycle locally or over a regional scale. Hence for understanding the processes altering the various sources, its isotopic signatures were studied. The Isotope Water Vapour Line (Iso Val) was drawn together with the Global Meteoric Water Line (GMWL) and the best fit line was δD = 5.42 * δ18O + 27.86. The precipitation samples were also collected during the study period and were best fitted with δD = 8.20(±0.18) * δ18O + 9.04(±1.16) in the Local Meteoric Water Line (LMWL). From the back trajectory analysis of respective vapor samples, it is unambiguous that three major sources viz; local vapor, western disturbance and monsoon vapor are controlling the fate of moisture over Roorkee. The d-excess in ground-level vapor (GLV) reveals the supply of recycled moisture from continental water bodies and evapo-transpiration as additional moisture sources to the study area. The intensive depletion in isotopic ratios was associated with the large-scale convective activity and low-pressure/cyclonic/depression systems formed over Bay of Bengal.

  4. Tropical Atlantic Hurricanes, Easterly Waves, and West African Mesoscale Convective Systems

    Directory of Open Access Journals (Sweden)

    Yves K. Kouadio

    2010-01-01

    Full Text Available The relationship between tropical Atlantic hurricanes (Hs, atmospheric easterly waves (AEWs, and West African mesoscale convective systems (MCSs is investigated. It points out atmospheric conditions over West Africa before hurricane formation. The analysis was performed for two periods, June–November in 2004 and 2005, during which 12 hurricanes (seven in 2004, five in 2005 were selected. Using the AEW signature in the 700 hPa vorticity, a backward trajectory was performed to the African coast, starting from the date and position of each hurricane, when and where it was catalogued as a tropical depression. At this step, using the Meteosat-7 satellite dataset, we selected all the MCSs around this time and region, and tracked them from their initiation until their dissipation. This procedure allowed us to relate each of the selected Hs with AEWs and a succession of MCSs that occurred a few times over West Africa before initiation of the hurricane. Finally, a dipole in sea surface temperature (SST was observed with a positive SST anomaly within the region of H generation and a negative SST anomaly within the Gulf of Guinea. This SST anomaly dipole could contribute to enhance the continental convergence associated with the monsoon that impacts on the West African MCSs formation.

  5. Luminescent nanocrystals in the rare-earth niobate–zirconia system formed via hydrothermal method

    International Nuclear Information System (INIS)

    Hirano, Masanori; Dozono, Hayato

    2013-01-01

    Luminescent nanocrystals based on the rare-earth niobates (Ln 3 NbO 7 , Ln=Y, Eu) and zirconia (ZrO 2 ) that were composed of 50 mol% Ln 3 NbO 7 and 50 mol% ZrO 2 , were hydrothermally formed as cubic phase under weakly basic conditions at 240 °C. The lattice parameter of the as-prepared nanoparticles corresponding to the composition of Y 3−x Eu x NbO 7 –4ZrO 2 that was estimated as a single phase of cubic gradually increased as the content of europium x increased. The existence of small absorbance peaks at 395 and 466 nm corresponding to the Eu 3+7 F 0 → 5 L 6 , and 7 F 0 → 5 D 2 excitation transition, respectively, was clearly observed in the diffuse reflectance spectra of the as-prepared samples containing europium. The optical band gap of the as-prepared samples was in the range from 3.5 to 3.7 eV. The photoluminescence spectra of the as-prepared nanocrystals containing europium showed orange and red luminescences with main peaks at 590 and 610 nm, corresponding to 5 D 0 → 7 F 1 and 5 D 0 → 7 F 2 transitions of Eu 3+ , respectively, under excitation at 395 nm Xe lamp. The emission intensity corresponding to 5 D 0 → 7 F 2 transition increased as heat-treatment temperature rose from 800 to 1200 °C. - Graphical abstract: This graphical abstract shows the excitation and emission spectra and a transmission electron microscopy image of nanocrystals (with composition based on the rare-earth niobates (Ln 3 NbO 7 , Ln=Y, Eu) and zirconia (ZrO 2 ) that were composed of 50 mol% Ln 3 NbO 7 and 50 mol% ZrO 2 ) formed via hydrothermal route. Display Omitted - Highlights: • Nanocrystals composed of 50 mol% Y 3−x Eu x NbO 7 and 50 mol% ZrO 2 was directly formed. • The nanocrystals were hydrothermally formed under weakly basic conditions at 240 °C. • The Y 3 NbO 7 showed an UV-blue and broad-band emission under excitation at 240 nm. • The emission is originated from the niobate octahedral group [NbO 6 ] 7− . • The nanocrystals showed orange and

  6. Measuring the vertical electrical field above an oceanic convection system using a meteorological sounding balloon

    Science.gov (United States)

    Chen, A. B.; Chiu, C.; Lai, S.; Chen, C.; Kuo, C.; Su, H.; Hsu, R.

    2012-12-01

    The vertical electric field above thundercloud plays an important role in the generation and modeling of transient luminous events. For example, Pasko [1995] proposed that the high quasi-static E-field following the positive cloud-to-ground lightning could accelerate and input energy to ambient electrons; as they collide and excite nitrogen and oxygen molecules in upper atmosphere, sprites may be induced. A series of balloon experiments led by Holzworth have investigated the temporal and spatial fluctuations of the electric field and conductivity in the upper atmosphere at different sites [Holzworth 2005, and references in]. But the strength and variation of the vertical electric field above thundercloud, especially oceanic ones, are not well documented so far. A lightweight, low-cost measurement system including an electric field meter and the associated aviation electronics are developed to carry out the in-situ measurement of the vertical electric field and the inter-cloud charge distribution. Our measuring system was first deployed using a meteorological sounding balloon from Taitung, Taiwan in May 2012. The measured electric field below 3km height shows an exponential decay and it is consistent with the expected potential gradient variation between ionosphere and the Earth surface. But the background strength of the measured E-field grows up exponentially and a violent fluctuations is also observed when the balloon flew over a developing oceanic convection cell. The preliminary results from this flight will be reported and discussed. This low-cost electric field meter is developed within one year. In the coming months, more flights will be performed with the aim to measure the rapid variation of the electric field above thundercloud as well as the E-field that may induce transient luminous events. Our ground campaigns show that the occurrence rates of blue and gigantic jet are relatively high in the vicinity of Taiwan. Our experiment can be used to diagnose

  7. Pattern selection in single-component systems coupling Benard convection and solidification

    International Nuclear Information System (INIS)

    Davis, S.H.; Mueller, U.; Dietsche, C.

    1983-12-01

    A horizontal layer is heated from below and cooled from above so that the enclosed single-component liquid is frozen in the upper part of the layer. When the imposed temperature difference is such that the Rayleigh number across the liquid is supercritical, there is Benard convection coupled with the dynamics of the solidification interface. An experiment is presented which shows that the interfacial corrugations that result are two-dimensional when this ''ice'' is thin but hexagonal when the ''ice'' is thick. A weakly-nonlinear convective instability theory is presented which explains this behavior, and isolates the mechanism of the pattern selection. Jump behavior is seen in the liquid-layer thickness at the onset of hexagonal convection. (orig.) [de

  8. Hydrothermal fluid flow within a tectonically active rift-ridge transform junction: Tjörnes Fracture Zone, Iceland

    Science.gov (United States)

    Lupi, M.; Geiger, S.; Graham, C. M.

    2010-05-01

    We investigate the regional fluid flow dynamics in a highly faulted transform area, the Tjörnes Fracture Zone in northern Iceland which is characterized by steep geothermal gradients, hydrothermal activity, and strong seismicity. We simulate fluid flow within the Tjörnes Fracture Zone using a high-resolution model that was based on the available geological and geophysical data and has the aim to represent the complex geological structures and the thermodynamical processes that drive the regional fluid flow in a physically realistic way. Our results show that convective heat flow and mixing of cold and saline seawater with deep hydrothermal fluids controls the large-scale fluid flow. The distribution of faults has a strong influence on the local hydrodynamics by focusing flow around clusters of faults. This explains the nature of isolated upflow zones of hot hydrothermal fluids which are observed in the Tjörnes Fracture Zone. An important emergent characteristic of the regional fluid flow in the Tjörnes Fracture Zone are two separate flow systems: one in the sedimentary basins, comprising more vigorous convection, and one in the crystalline basement, which is dominated by conduction. These two flow systems yield fundamental insight into the connection between regional hydrothermal fluid flow and seismicity because they form the basis of a toggle switch mechanism that is thought to have caused the hydrogeochemical anomalies recorded at Húsavik before and after the 5.8 M earthquake in September 2002.

  9. Energy sources for chemolithotrophs in an arsenic- and iron-rich shallow-sea hydrothermal system.

    Science.gov (United States)

    Akerman, N H; Price, R E; Pichler, T; Amend, J P

    2011-09-01

    The hydrothermally influenced sediments of Tutum Bay, Ambitle Island, Papua New Guinea, are ideal for investigating the chemolithotrophic activities of micro-organisms involved in arsenic cycling because hydrothermal vents there expel fluids with arsenite (As(III)) concentrations as high as 950 μg L(-1) . These hot (99 °C), slightly acidic (pH ~6), chemically reduced, shallow-sea vent fluids mix with colder, oxidized seawater to create steep gradients in temperature, pH, and concentrations of As, N, Fe, and S redox species. Near the vents, iron oxyhydroxides precipitate with up to 6.2 wt% arsenate (As(V)). Here, chemical analyses of sediment porewaters from 10 sites along a 300-m transect were combined with standard Gibbs energies to evaluate the energy yields (-ΔG(r)) from 19 potential chemolithotrophic metabolisms, including As(V) reduction, As(III) oxidation, Fe(III) reduction, and Fe(II) oxidation reactions. The 19 reactions yielded 2-94 kJ mol(-1) e(-) , with aerobic oxidation of sulphide and arsenite the two most exergonic reactions. Although anaerobic As(V) reduction and Fe(III) reduction were among the least exergonic reactions investigated, they are still potential net metabolisms. Gibbs energies of the arsenic redox reactions generally correlate linearly with pH, increasing with increasing pH for As(III) oxidation and decreasing with increasing pH for As(V) reduction. The calculated exergonic energy yields suggest that micro-organisms could exploit diverse energy sources in Tutum Bay, and examples of micro-organisms known to use these chemolithotrophic metabolic strategies are discussed. Energy modeling of redox reactions can help target sampling sites for future microbial collection and cultivation studies. © 2011 Blackwell Publishing Ltd.

  10. A Geographical Information System to Manage the Endeavour Hydrothermal Vents Marine Protected Area

    Science.gov (United States)

    Douglas, K. L.; Hillier, M. C. J.; Thornborough, K. J.; Jenkyns, R.; Juniper, K.

    2016-02-01

    The Endeavour Hydrothermal Vents Marine Protected Area (EHVMPA) is located approximately 250 km offshore of Vancouver Island, British Columbia. Since its discovery in 1982, there have been hundreds of dives, samples collected, measurements made, and debris left behind at the EHVMPA. In 2003, the Canadian government declared the region as a Marine Protected Area (MPA) under Canada's Oceans Act, to be managed by the Department of Fisheries and Oceans (DFO). Ocean Networks Canada (ONC) operates a cabled observatory in the EHVMPA, and streams data in near real-time via the Internet to science communities worldwide. ONC's observatory data, combined with observations made during maintenance expeditions provides insight assisting the management and preservation of the MPA. In 2014, DFO partnered with ONC to build a geodatabase to enhance and inform the knowledge base of the EHVMPA Management Plan. The geodatabase, built in ArcGIS, contains data integrated from ONC's Oceans 2.0 database, third parties, and relevant publications. Layers include annual observatory infrastructure deployments, remotely operated vehicle (ROV) dive tracks, sampling activity, anthropogenic debris, high-resolution bathymetry, observations of species of interest, and locations of hydrothermal vents. The combined data show both efforts to better understand the environment and the resulting stressors that impact the MPA. The tool also links observed features such as debris and biological observations to the time-correlated ROV dive video using ONC's SeaTube video viewing tool allowing for further analysis. Through 2017, the geodatabase will be maintained by ONC and enriched with expedition data from organizations such as Monterey Bay Aquarium Research Institute, Woods Hole Oceanographic Institute, and the University of Washington. The end result is a tool that can integrate many types of data obtained from the MPA, and encourages systematic management of a remote, dynamic and fragile environment.

  11. Fine-scale heat flow, shallow heat sources, and decoupled circulation systems at two sea-floor hydrothermal sites, Middle Valley, northern Juan de Fuca Ridge

    Science.gov (United States)

    Stein, J. S.; Fisher, A. T.; Langseth, M.; Jin, W.; Iturrino, G.; Davis, E.

    1998-12-01

    Fine-scale heat-flow patterns at two areas of active venting in Middle Valley, a sedimented rift on the northern Juan de Fuca Ridge, provide thermal evidence of shallow hydrothermal reservoirs beneath the vent fields. The extreme variability of heat flow is explained by conductive heating immediately adjacent to vents and shallow circulation within sediments above the reservoir. This secondary circulation is hydrologically separated from the deeper system feeding the vents by a shallow conductive lid within the sediments. A similar separation of shallow and deep circulation may also occur at sediment-free ridge-crest hydrothermal environments.

  12. Numerical Modeling of Conjugate Thermogravitational Convection in a Closed System with a Radiant Energy Source in Conditions of Convective-Radiative Heat Exchange at the External Boundary

    Directory of Open Access Journals (Sweden)

    Nee Alexander

    2016-01-01

    Full Text Available Mathematical modeling of conjugate natural convection in a closed rectangular cavity with a radiant energy source in conditions of convective-radiative heat exchange at the external boundary was conducted. The radiant energy distribution was set by the Lambert’s law. Conduction and convection processes analysis showed that the air masses flow pattern is modified slightly over the time. The temperature increases in the gas cavity, despite the heat removal from the one of the external boundary. According to the results of the integral heat transfer analysis were established that the average Nusselt number (Nuav increasing occurs up to τ = 200 (dimensionless time. Further Nuav has changed insignificantly due to the temperature field equalization near the interfaces “gas – wall”.

  13. Fluid transfer and vein thickness distribution in high and low temperature hydrothermal systems at shallow crustal level in southern Tuscany (Italy

    Directory of Open Access Journals (Sweden)

    Francesco Mazzarini

    2014-06-01

    Full Text Available Geometric analysis of vein systems hosted in upper crustal rocks and developed in high and low temperature hydrothermal systems is presented. The high temperature hydrothermal system consists of tourmaline-rich veins hosted within the contact aureole of the upper Miocene Porto Azzurro pluton in the eastern Elba Island. The low temperature hydrothermal system consists of calcite-rich veins hosted within the Oligocene sandstones of the Tuscan Nappe, exposed along the coast in southern Tuscany. Vein thickness distribution is here used as proxy for inferring some hydraulic properties (transmissivity of the fluid circulation at the time of veins’ formation. We derive estimations of average thickness of veins by using the observed distributions. In the case of power law thickness distributions, the lower the scaling exponent of the distribution the higher the overall transmissivity. Indeed, power law distributions characterised by high scaling exponents have transmissivity three order of magnitude lower than negative exponential thickness distribution. Simple observations of vein thickness may thus provides some clues on the transmissivity in hydrothermal systems.

  14. Seasonal and Intraseasonal Variability of Mesoscale Convective Systems over the South Asian Monsoon Region

    Energy Technology Data Exchange (ETDEWEB)

    Virts, Katrina S.; Houze, Robert A.

    2016-12-01

    Seasonal and intraseasonal differences in mesoscale convective systems (MCSs) over South Asia are examined using A-Train satellites, a ground-based lightning network, and reanalysis fields. Pre-monsoon (April-May) MCSs occur primarily over Bangladesh and the eastern Bay of Bengal. During the monsoon (June-September), small MCSs occur over the Meghalaya Plateau and northeast Himalayan notch, while large and connected MCSs are most widespread over the Bay of Bengal. Monsoon MCSs produce less lightning and exhibit more extensive stratiform and anvil reflectivity structures in CloudSat observations than do pre-monsoon MCSs. During the monsoon season, Bay of Bengal and Meghalaya Plateau MCSs vary with the 30-60 day northward-propagating intraseasonal oscillation, while northeast Himalayan notch MCSs are associated with weak large-scale anomalies but locally enhanced CAPE. During intraseasonal active periods, a zone of enhanced large and connected MCSs, precipitation, and lightning extends from the northeastern Arabian Sea southeast over India and the Bay of Bengal, flanked by suppressed anomalies. Spatial variability is observed within this enhancement zone: lightning is most enhanced where MCSs are less enhanced, and vice versa. Reanalysis composites indicate that Bay of Bengal MCSs are associated with monsoon depressions, which are frequent during active monsoon periods, while Meghalaya Plateau MCSs are most frequent at the end of break periods, as anomalous southwesterly winds strengthen moist advection toward the terrain. Over both regions, MCSs exhibit more extensive stratiform and anvil regions and less lightning when the large-scale environment is moister, and vice versa.

  15. Argentine hydrothermal panorama

    Energy Technology Data Exchange (ETDEWEB)

    1976-12-01

    An attempt is made to give a realistic review of Argentine thermal waters. The topics discussed are the characteristics of the hydrothermal resources, classification according to their mineral content, hydrothermal flora and fauna, uses of hydrothermal resources, hydrothermal regions of Argentina, and meteorology and climate. A tabulation is presented of the principal thermal waters. (JSR)

  16. A Multiobjective Interval Programming Model for Wind-Hydrothermal Power System Dispatching Using 2-Step Optimization Algorithm

    Science.gov (United States)

    Jihong, Qu

    2014-01-01

    Wind-hydrothermal power system dispatching has received intensive attention in recent years because it can help develop various reasonable plans to schedule the power generation efficiency. But future data such as wind power output and power load would not be accurately predicted and the nonlinear nature involved in the complex multiobjective scheduling model; therefore, to achieve accurate solution to such complex problem is a very difficult task. This paper presents an interval programming model with 2-step optimization algorithm to solve multiobjective dispatching. Initially, we represented the future data into interval numbers and simplified the object function to a linear programming problem to search the feasible and preliminary solutions to construct the Pareto set. Then the simulated annealing method was used to search the optimal solution of initial model. Thorough experimental results suggest that the proposed method performed reasonably well in terms of both operating efficiency and precision. PMID:24895663

  17. A multiobjective interval programming model for wind-hydrothermal power system dispatching using 2-step optimization algorithm.

    Science.gov (United States)

    Ren, Kun; Jihong, Qu

    2014-01-01

    Wind-hydrothermal power system dispatching has received intensive attention in recent years because it can help develop various reasonable plans to schedule the power generation efficiency. But future data such as wind power output and power load would not be accurately predicted and the nonlinear nature involved in the complex multiobjective scheduling model; therefore, to achieve accurate solution to such complex problem is a very difficult task. This paper presents an interval programming model with 2-step optimization algorithm to solve multiobjective dispatching. Initially, we represented the future data into interval numbers and simplified the object function to a linear programming problem to search the feasible and preliminary solutions to construct the Pareto set. Then the simulated annealing method was used to search the optimal solution of initial model. Thorough experimental results suggest that the proposed method performed reasonably well in terms of both operating efficiency and precision.

  18. Determining ice water content from 2D crystal images in convective cloud systems

    Science.gov (United States)

    Leroy, Delphine; Coutris, Pierre; Fontaine, Emmanuel; Schwarzenboeck, Alfons; Strapp, J. Walter

    2016-04-01

    Cloud microphysical in-situ instrumentation measures bulk parameters like total water content (TWC) and/or derives particle size distributions (PSD) (utilizing optical spectrometers and optical array probes (OAP)). The goal of this work is to introduce a comprehensive methodology to compute TWC from OAP measurements, based on the dataset collected during recent HAIC (High Altitude Ice Crystals)/HIWC (High Ice Water Content) field campaigns. Indeed, the HAIC/HIWC field campaigns in Darwin (2014) and Cayenne (2015) provide a unique opportunity to explore the complex relationship between cloud particle mass and size in ice crystal environments. Numerous mesoscale convective systems (MCSs) were sampled with the French Falcon 20 research aircraft at different temperature levels from -10°C up to 50°C. The aircraft instrumentation included an IKP-2 (isokinetic probe) to get reliable measurements of TWC and the optical array probes 2D-S and PIP recording images over the entire ice crystal size range. Based on the known principle relating crystal mass and size with a power law (m=α•Dβ), Fontaine et al. (2014) performed extended 3D crystal simulations and thereby demonstrated that it is possible to estimate the value of the exponent β from OAP data, by analyzing the surface-size relationship for the 2D images as a function of time. Leroy et al. (2015) proposed an extended version of this method that produces estimates of β from the analysis of both the surface-size and perimeter-size relationships. Knowing the value of β, α then is deduced from the simultaneous IKP-2 TWC measurements for the entire HAIC/HIWC dataset. The statistical analysis of α and β values for the HAIC/HIWC dataset firstly shows that α is closely linked to β and that this link changes with temperature. From these trends, a generalized parameterization for α is proposed. Finally, the comparison with the initial IKP-2 measurements demonstrates that the method is able to predict TWC values

  19. Geophysical and geochemical methods applied to investigate fissure-related hydrothermal systems on the summit area of Mt. Etna volcano (Italy)

    Science.gov (United States)

    Maucourant, Samuel; Giammanco, Salvatore; Greco, Filippo; Dorizon, Sophie; Del Negro, Ciro

    2014-06-01

    A multidisciplinary approach integrating self-potential, soil temperature, heat flux, CO2 efflux and gravity gradiometry signals was used to investigate a relatively small fissure-related hydrothermal system near the summit of Mt. Etna volcano (Italy). Measurements were performed through two different surveys carried out at the beginning and at the end of July 2009, right after the end of the long-lived 2008-2009 flank eruption and in coincidence with an increase in diffuse flank degassing related to a reactivation of the volcano, leading to the opening of a new summit vent (NSEC). The main goal was to use a multidisciplinary approach to the detection of hidden fractures in an area of evident near-surface hydrothermal activity. Despite the different methodologies used and the different geometry of the sampling grid between the surveys, all parameters concurred in confirming that the study area is crossed by faults related with the main fracture systems of the south flank of the volcano, where a continuous hydrothermal circulation is established. Results also highlighted that hydrothermal activity in this area changed both in space and in time. These changes were a clear response to variations in the magmatic system, notably to migration of magma at various depth within the main feeder system of the volcano. The results suggest that this specific area, initially chosen as the optimal test-site for the proposed approach, can be useful in order to get information on the potential reactivation of the summit craters of Mt. Etna.

  20. Magnetic fabrics and fluid flow directions in hydrothermal systems. A case study in the Chaillac Ba-F-Fe deposits (France)

    Science.gov (United States)

    Sizaret, Stanislas; Chen, Yan; Chauvet, Alain; Marcoux, Eric; Touray, Jean Claude

    2003-02-01

    This study presents a possible use of anisotropy of magnetic susceptibility (AMS) to describe the mineralizing process in hydrothermal systems. Ba-F-Fe-rich deposits within the Chaillac Basin are on the southern border of the Paris Basin. In these deposits hydrothermal textures and tectonic structures have been described in veins, sinters, and sandstone cemented by hydrothermal goethite. 278 oriented cores from 24 sites have been collected in these formations. In addition, a lateritic duricrust superimposed on the hydrothermal formation has been sampled. Rock magnetic investigations show that the principal magnetic carrier is goethite for the hydrothermal mineralization and for the laterite level. The AMS measurements show distinguishable behaviors in the different mineralogical and geological contexts. The K1 magnetic lineation (maximum axis) is strongly inclined for the vertical veins. For the horizontally mineralized sinters, the magnetic lineation is almost horizontal with an azimuth similar to the sedimentary flow direction. The AMS of goethite-rich sandstone close to the veins shows strongly inclined K1 as they are probably influenced by the vertical veins; however, when the distance from the vein is larger than 1 m, the AMS presents rather horizontal K1 directions, parallel to the sedimentary flow. The laterite has a foliation dominance of AMS with vertically well-grouped K3 axes and scattered K1 and K2 axes. Field structural observations suggest that the ore deposit is mainly controlled by EW extension tectonics associated with NS trending normal faults. Combining the AMS results on the deposit with vein textures and field data a model is proposed in which AMS results are interpreted in terms of hydrothermal fluid flow. This work opens a new investigation field to constrain hydrodynamic models using the AMS method. Textural study combined with efficient AMS fabric measurements should be used for systematic investigation to trace flow direction in fissures

  1. Hydrothermal liquefaction of biomass

    DEFF Research Database (Denmark)

    Toor, Saqib; Rosendahl, Lasse; Hoffmann, Jessica

    2014-01-01

    Biomass is one of the most abundant sources of renewable energy, and will be an important part of a more sustainable future energy system. In addition to direct combustion, there is growing attention on conversion of biomass into liquid en-ergy carriers. These conversion methods are divided...... into biochemical/biotechnical methods and thermochemical methods; such as direct combustion, pyrolysis, gasification, liquefaction etc. This chapter will focus on hydrothermal liquefaction, where high pressures and intermediate temperatures together with the presence of water are used to convert biomass...... into liquid biofuels, with the aim of describing the current status and development challenges of the technology. During the hydrothermal liquefaction process, the biomass macromolecules are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive...

  2. Effects of resolved boundary layer turbulence on near-ground rotation in simulated quasi-linear convective systems (QLCSs)

    Science.gov (United States)

    Nowotarski, C. J.

    2017-12-01

    Though most strong to violent tornadoes are associated with supercell thunderstorms, quasi-linear convective systems (QLCSs) pose a risk of tornadoes, often at times and locations where supercell tornadoes are less common. Because QLCS low-level mesocyclones and tornado signatures tend to be less coherent, forecasting such tornadoes remains particularly difficult. The majority of simulations of such storms rely on horizontally homogeneous base states lacking resolved boundary layer turbulence and surface fluxes. Previous work has suggested that heterogeneities associated with boundary layer turbulence in the form of horizontal convective rolls can influence the evolution and characteristics of low-level mesocyclones in supercell thunderstorms. This study extends methods for generating boundary layer convection to idealized simulations of QLCSs. QLCS simulations with resolved boundary layer turbulence will be compared against a control simulation with a laminar boundary layer. Effects of turbulence, the resultant heterogeneity in the near-storm environment, and surface friction on bulk storm characteristics and the intensity, morphology, and evolution of low-level rotation will be presented. Although maximum surface vertical vorticity values are similar, when boundary layer turbulence is included, a greater number of miso- and meso-scale vortices develop along the QLCS gust front. The source of this vorticity is analyzed using Eulerian decomposition of vorticity tendency terms and trajectory analysis to delineate the relative importance of surface friction and baroclinicity in generating QLCS vortices. The role of anvil shading in suppressing boundary layer turbulence in the near-storm environment and subsequent effects on QLCS vortices will also be presented. Finally, implications of the results regarding inclusion of more realistic boundary layers in future idealized simulations of deep convection will be discussed.

  3. Numerical Analyses of a single-phase natural convection system for Molten Flibe using MARS-FLIBE code

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sarah; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    These advantages make the MSR attractive and to be one of the six candidates for the Generation IV Reactor. Therefore, the researches related to the MSR are being conducted. To analyze the molten salt-cooled systems in the laboratory, this study generated the properties of molten salt using MARS-LMR. In this research, the implemented salts were Flibe (LiF-BeF{sub 2}) in a molar mixture that is 66% LiF and 34% BeF{sub 2}, respectively. Table 1 indicates the comparison of thermal properties of various coolants in nuclear power plants. Molten salt was added to the MARS-LMR code to support the analysis of Flibe-cooled systems. The molten salt includes LiF-BeF{sub 2} in a molar mixture that is 66% LiF and 34% BeF{sub 2}, respectively. MARS-LMR code for liquid metals uses the soft sphere model based on Monte Carlo calculations for particles interacting with pair potentials. Although MARS was originally intended for a safety analysis of light water reactor, Flibe properties were newly added to this code as so-called MARS-FLIBE which is applicable for Flibe-cooled systems. By using this thermodynamic property table file, the thermal hydraulic systems of Flibe can be simulated for numerical and parametric studies. In this study, the natural convection phenomena in the rectangular natural convection loop and IVR-ERVC in APR 1400 were simulated. Through the simulations in Flibe-cooled systems, the temperature distribution and mass flowrate of Flibe can be calculated and the heat transfer coefficients of Flibe in natural convection loop will be calculated by adding the related heat transfer correlations in the MARS-FLIBE code. MARS-FLIBE code will be used to predict and design of Flibe-cooled systems.

  4. Geology and mineralogy of the Auki Crater, Tyrrhena Terra, Mars: A possible post impact-induced hydrothermal system

    Science.gov (United States)

    Carrozzo, F. G.; Di Achille, G.; Salese, F.; Altieri, F.; Bellucci, G.

    2017-01-01

    A variety of hydrothermal environments have been documented in terrestrial impact structures. Due to both past water interactions and meteoritic bombardment on the surface of Mars, several authors have predicted various scenarios that include the formation of hydrothermal systems. Geological and mineralogical evidence of past hydrothermal activity have only recently been found on Mars. Here, we present a geological and mineralogical study of the Auki Crater using the spectral and visible imagery data acquired by the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars), CTX (Context Camera) and HiRISE (High Resolution Imaging Science Experiment) instruments on board the NASA MRO mission. The Auki Crater is a complex crater that is ∼38 km in diameter located in Tyrrhena Terra (96.8°E and 15.7°S) and shows a correlation between its mineralogy and morphology. The presence of minerals, such as smectite, silica, zeolite, serpentine, carbonate and chlorite, associated with morphological structures, such as mounds, polygonal terrains, fractures and veins, suggests that the Auki Crater may have hosted a post impact-induced hydrothermal system. Although the distribution of hydrated minerals in and around the central uplift and the stratigraphic relationships of some morphological units could also be explained by the excavation and exhumation of carbonate-rich bedrock units as a consequence of crater formation, we favor the hypothesis of impact-induced hydrothermal circulation within fractures and subsequent mineral deposition. The hydrothermal system could have been active for a relatively long period of time after the impact, thus producing a potential transient habitable environment. It must be a spectrally neutral component to emphasize the spectral features; It is an average of spectra taken in the same column of the numerator spectra to correct the residual instrument artifacts and reduce detector noise that changes from column to column; It must be taken in

  5. Micro-seismic earthquakes characteristics at natural and exploited hydrothermal systems in West Java, Indonesia

    Science.gov (United States)

    Jousset, P. G.; Jaya, M. S.; Sule, R.; Diningrat, W.; Gassner, A.; Akbar, F.; Ryannugroho, R.; Hendryana, A.; Kusnadi, Y.; Syahbana, D.; Nugraha, A. D.; Umar, M.; Indrinanto, Y.; Erbas, K.

    2013-12-01

    The assessment of geothermal resources requires the understanding of the structure and the dynamics of geothermal reservoirs. We deployed a multidisciplinary geophysical network around geothermal areas in the south of Bandung, West Java, Indonesia. The first deployment included a network of 30 broadband and 4 short-period seismic stations with Güralp and Trillium sensors (0.008 - 100 Hz) since October 2012. In a second step, we extended the network in June 2013 with 16 short-period (1 Hz) seismometers. We describe the set-up of the seismic networks and discuss first observations and results. The co-existence of a large variety of intense surface manifestations like geysers, hot-steaming grounds, hot water pools, and active volcanoes suggest an intimate coupling between volcanic, tectonic and hydrothermal processes in this area. Preliminary location of earthquakes is performed using a non-linear algorithm, which allows us to define at least 3 seismic clusters. We discuss this seismic pattern within the geothermal fields.

  6. Fungal diversity in deep-sea sediments of a hydrothermal vent system in the Southwest Indian Ridge

    Science.gov (United States)

    Xu, Wei; Gong, Lin-feng; Pang, Ka-Lai; Luo, Zhu-Hua

    2018-01-01

    Deep-sea hydrothermal sediment is known to support remarkably diverse microbial consortia. In deep sea environments, fungal communities remain less studied despite their known taxonomic and functional diversity. High-throughput sequencing methods have augmented our capacity to assess eukaryotic diversity and their functions in microbial ecology. Here we provide the first description of the fungal community diversity found in deep sea sediments collected at the Southwest Indian Ridge (SWIR) using culture-dependent and high-throughput sequencing approaches. A total of 138 fungal isolates were cultured from seven different sediment samples using various nutrient media, and these isolates were identified to 14 fungal taxa, including 11 Ascomycota taxa (7 genera) and 3 Basidiomycota taxa (2 genera) based on internal transcribed spacers (ITS1, ITS2 and 5.8S) of rDNA. Using illumina HiSeq sequencing, a total of 757,467 fungal ITS2 tags were recovered from the samples and clustered into 723 operational taxonomic units (OTUs) belonging to 79 taxa (Ascomycota and Basidiomycota contributed to 99% of all samples) based on 97% sequence similarity. Results from both approaches suggest that there is a high fungal diversity in the deep-sea sediments collected in the SWIR and fungal communities were shown to be slightly different by location, although all were collected from adjacent sites at the SWIR. This study provides baseline data of the fungal diversity and biogeography, and a glimpse to the microbial ecology associated with the deep-sea sediments of the hydrothermal vent system of the Southwest Indian Ridge.

  7. Heat Convection

    Science.gov (United States)

    Jiji, Latif M.

    Professor Jiji's broad teaching experience lead him to select the topics for this book to provide a firm foundation for convection heat transfer with emphasis on fundamentals, physical phenomena, and mathematical modelling of a wide range of engineering applications. Reflecting recent developments, this textbook is the first to include an introduction to the challenging topic of microchannels. The strong pedagogic potential of Heat Convection is enhanced by the follow ing ancillary materials: (1) Power Point lectures, (2) Problem Solutions, (3) Homework Facilitator, and, (4) Summary of Sections and Chapters.

  8. The response of a simulated mesoscale convective system to increased aerosol pollution: Part I: Precipitation intensity, distribution, and efficiency

    Science.gov (United States)

    Clavner, Michal; Cotton, William R.; van den Heever, Susan C.; Saleeby, Stephen M.; Pierce, Jeffery R.

    2018-01-01

    Mesoscale Convective Systems (MCSs) are important contributors to rainfall in the High Plains of the United States and elsewhere in the world. It is therefore of interest to understand how different aerosols serving as cloud condensation nuclei (CCN) may impact the total amount, rates and spatial distribution of precipitation produced by MCSs. In this study, different aerosol concentrations and their effects on precipitation produced by an MCS are examined by simulating the 8 May 2009 "Super-Derecho" MCS using the Regional Atmospheric Modeling System (RAMS), a cloud-resolving model (CRM) with sophisticated aerosol and microphysical parameterizations. Three simulations were conducted that differed only in the initial concentration, spatial distribution, and chemical composition of aerosols. Aerosol fields were derived from the output of GEOS-Chem, a 3D chemical transport numerical model. Results from the RAMS simulations show that the total domain precipitation was not significantly affected by variations in aerosol concentrations, however, the pollution aerosols altered the precipitation characteristics. The more polluted simulations exhibited higher precipitation rates, higher bulk precipitation efficiency, a larger area with heavier precipitation, and a smaller area with lighter precipitation. These differences arose as a result of aerosols enhancing precipitation in the convective region of the MCS while suppressing precipitation from the MCS's stratiform-anvil. In the convective region, several processes likely contributed to an increase of precipitation. First, owing to the very humid environment of this storm, the enhanced amount of cloud water available to be collected overwhelmed the reduction in precipitation efficiency associated with the aerosol-induced production of smaller droplets which led to a net increase in the conversion of cloud droplets to precipitation. Second, higher aerosol concentrations led to invigoration of convective updrafts which

  9. Topological defects after a quench in a Bénard-Marangoni convection system.

    Science.gov (United States)

    Casado, S; González-Viñas, W; Mancini, H; Boccaletti, S

    2001-05-01

    We report experimental evidence of the fact that, in a Bénard-Marangoni conduction-convection transition, the density of defects in the emerging structure scales as a power law in the quench time needed for the control parameter to ramp through the threshold. The obtained scaling exponents differ from the ones predicted and observed in the case in which the defects correspond to zeros in the amplitude of the global two-dimensional field.

  10. A Novel Observation-Guided Approach for Evaluating Mesoscale Convective Systems Simulated by the DOE ACME Model

    Science.gov (United States)

    Feng, Z.; Ma, P. L.; Hardin, J. C.; Houze, R.

    2017-12-01

    Mesoscale convective systems (MCSs) are the largest type of convective storms that develop when convection aggregates and induces mesoscale circulation features. Over North America, MCSs contribute over 60% of the total warm-season precipitation and over half of the extreme daily precipitation in the central U.S. Our recent study (Feng et al. 2016) found that the observed increases in springtime total and extreme rainfall in this region are dominated by increased frequency and intensity of long-lived MCSs*. To date, global climate models typically do not run at a resolution high enough to explicitly simulate individual convective elements and may not have adequate process representations for MCSs, resulting in a large deficiency in projecting changes of the frequency of extreme precipitation events in future climate. In this study, we developed a novel observation-guided approach specifically designed to evaluate simulated MCSs in the Department of Energy's climate model, Accelerated Climate Modeling for Energy (ACME). The ACME model has advanced treatments for convection and subgrid variability and for this study is run at 25 km and 100 km grid spacings. We constructed a robust MCS database consisting of over 500 MCSs from 3 warm-season observations by applying a feature-tracking algorithm to 4-km resolution merged geostationary satellite and 3-D NEXRAD radar network data over the Continental US. This high-resolution MCS database is then down-sampled to the 25 and 100 km ACME grids to re-characterize key MCS properties. The feature-tracking algorithm is adapted with the adjusted characteristics to identify MCSs from ACME model simulations. We demonstrate that this new analysis framework is useful for evaluating ACME's warm-season precipitation statistics associated with MCSs, and provides insights into the model process representations related to extreme precipitation events for future improvement. *Feng, Z., L. R. Leung, S. Hagos, R. A. Houze, C. D. Burleyson

  11. Effect of reaction systems and surfactant additives on the morphology evolution of hydroxyapatite nanorods obtained via a hydrothermal route

    Energy Technology Data Exchange (ETDEWEB)

    Ma Tianyuan; Xia Zhiguo [School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China); Liao Libing, E-mail: lbliao@cugb.edu.cn [School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China)

    2011-02-15

    Well-dispersed hydroxyapatite (HA) nanorods with different morphologies were synthesized by a hydrothermal method in oleic acid, ethanol and water reaction system, and the surfactant assisted modifications effect was also comparatively studied. The structure and morphology of samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM), respectively. The effect of reaction systems and surfactant additives on the morphology evolution of HA nanorods were discussed in detail. The results showed that the controlled experimental conditions in the systems, such as the content ratio of oleic acid/ethanol, pH value and the content ratio of Ca/P source had an significant effect on the morphology evolution of as-prepared HA nanorods. Further, the selected surfactant additives, such as cetyltriethylammnonium bromide (CTAB), sodium dodecyl sulfate (K12) also play an important role in the formation of the uniform morphology of HA nanorods. Some possible formation mechanisms of the HA nanorods in the present reaction systems is proposed.

  12. Rock deformation in hydrothermal systems: the nature of fractures in plutons and their host rocks. Technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Norton, D.

    1981-11-01

    The purpose of this program is to accumulate the types of field data which are important for the analysis of magma-hydrothermal systems. The structural effects of thermal processes were identified in order to distinguish the thermally induced deformations from the deformations that occurred subsequent to complete cooling of the system. Mapping techniques were developed to record the structural data on the ground from local domains characteristic of larger areas in the magma chamber, and in the air from low-angle oblique aerial photography of the entire region. The ground system is complete and preliminary testing is currently being carried out to verify the method. The results indicate that granitic crystalline rocks have no structural resistance to thermal perturbations. If nuclear wastes are to be stored in granite, precautionary buffers would have to be incorporated into the system. A total of 30 fossil magma chambers have been studied over the past 2 years. An extensive set of fracture imagery has been collected, together with information related to the geological history of the plutons. Fossil magma chambers in Arizona, Utah, California, Washington, Montana, and British Columbia have been studied.

  13. Selected data for low-temperature (less than 90{sup 0}C) geothermal systems in the United States: reference data for US Geological Survey Circular 892

    Energy Technology Data Exchange (ETDEWEB)

    Reed, M.J.; Mariner, R.H.; Brook, C.A.; Sorey, M.L.

    1983-12-15

    Supporting data are presented for the 1982 low-temperature geothermal resource assessment of the United States. Data are presented for 2072 geothermal sites which are representative of 1168 low-temperature geothermal systems identified in 26 States. The low-temperature geothermal systems consist of 978 isolated hydrothermal-convection systems, 148 delineated-area hydrothermal-convection systems, and 42 delineated-area conduction-dominated systems. The basic data and estimates of reservoir conditions are presented for each geothermal system, and energy estimates are given for the accessible resource base, resource, and beneficial heat for each isolated system.

  14. Petrology, chronology and sequence of vein systems: Systematic magmatic and hydrothermal history of a major intracontinental shear zone, Canadian Appalachians

    Science.gov (United States)

    Pe-Piper, Georgia; Piper, David J. W.; McFarlane, Chris R. M.; Sangster, Chris; Zhang, Yuanyuan; Boucher, Brandon

    2018-04-01

    Intra-continental shear zones developed during continental collision may experience prolonged magmatism and mineralization. The Cobequid Shear Zone formed part of a NE-SW-trending, orogen-parallel shear system in the late Devonian-early Carboniferous, where syn-tectonic granite-gabbro plutons and volcanic rocks 4 km thick were progressively deformed. In late Carboniferous to Permian, Alleghanian collision of Africa with Laurentia formed the E-W trending Minas Fault Zone, reactivating parts of the Cobequid Shear Zone. The 50 Ma history of hydrothermal mineralization following pluton emplacement is difficult to resolve from field relationships of veins, but SEM study of thin sections provides clear detail on the sequence of mineralization. The general paragenesis is: albite ± quartz ± chlorite ± monazite → biotite → calcite, allanite, pyrite → Fe-carbonates, Fe-oxides, minor sulfides, calcite and synchysite. Chronology was determined from literature reports and new U-Pb LA-ICPMS dating of monazite and allanite in veins. Vein mineralization was closely linked to magmatic events. Vein emplacement occurred preferentially during fault movement recognised from basin-margin inversion, as a result of fractures opening in the damage zone of master faults. The sequence of mineralization, from ca. 355 Ma riebeckite and albite veins to ca. 327 (-305?) Ma siderite-magnetite and sulfide mineralization, resembles Precambrian iron-oxide-copper-gold (IOCG) systems in the literature. The abundant magmatic Na, halogens and CO2 in veins and some magmatic bodies, characteristic of IOCG systems, were derived from the deeply subducted Rheic Ocean slab with little terrigenous sediment. Regional extension of the Magdalen Basin caused asthenospheric upwelling and melting of the previously metasomatized sub-continental lithospheric mantle. Crustal scale strike-slip faulting facilitated the rise of magmas, resulting in high heat flow driving an active hydrothermal system. Table S2

  15. The physical hydrology of magmatic-hydrothermal systems: High-resolution 18O records of magmatic-meteoric water interaction from the Yankee Lode tin deposit (Mole Granite, Australia)

    Science.gov (United States)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Heinrich, Christoph A.; Baumgartner, Lukas; Bouvier, Anne-Sophie

    2016-04-01

    Magmatic-hydrothermal ore deposits are important economic Cu, Au, Mo and Sn resources (Sillitoe, 2010, Kesler, 1994). The ore formation is a result of superimposed enrichment processes and metals can precipitate due to fluid-rock interaction and/or temperature drop caused by convection or mixing with meteoric fluid (Heinrich and Candela 2014). Microthermometry and LA-ICP MS trace element analyses of fluid inclusions of a well-characterized quartz sample from the Yankee Lode quartz-cassiterite vein deposit (Mole Granite, Australia) suggest that tin precipitation was driven by dilution of hot magmatic water by meteoric fluids (Audétat et al.1998). High resolution in situ oxygen isotope measurements of quartz have the potential to detect changing fluid sources during the evolution of a hydrothermal system. We analyzed the euhedral growth zones of this previously well-studied quartz sample. Growth temperatures are provided by Audétat et al. (1998) and Audétat (1999). Calculated δ 18O values of the quartz- and/or cassiterite-precipitating fluid show significant variability through the zoned crystal. The first and second quartz generations (Q1 and Q2) were precipitated from a fluid of magmatic isotopic composition with δ 18O values of ˜ 8 - 10 ‰. δ 18O values of Q3- and tourmaline-precipitating fluids show a transition from magmatic δ 18O values of ˜ 8 ‰ to ˜ -5 ‰. The outermost quartz-chlorite-muscovite zone was precipitated from a fluid with a significant meteoric water component reflected by very light δ 18O values of about -15 ‰ which is consistent with values found by previous studies (Sun and Eadington, 1987) using conventional O-isotope analysis of veins in the distal halo of the granite intrusion. Intense incursion of meteoric water during Q3 precipitation (light δ 18O values) agrees with the main ore formation event, though the first occurrence of cassiterite is linked to Q2 precipitating fluid with magmatic-like isotope signature. This

  16. Vapour discharges on Nevado del Ruiz during the recent activity: Clues on the composition of the deep hydrothermal system and its effects on thermal springs

    Science.gov (United States)

    Federico, Cinzia; Inguaggiato, Salvatore; Chacón, Zoraida; Londoño, John Makario; Gil, Edwing; Alzate, Diego

    2017-10-01

    The Nevado del Ruiz volcano is considered one of the most active volcanoes in Colombia, which can potentially threaten approximately 600,000 inhabitants. The existence of a glacier and several streams channelling in some main rivers, flowing downslope, increases the risk for the population living on the flank of the volcano in case of unrest, because of the generation of lahars and mudflows. Indeed, during the November 1985 subplinian eruption, a lahar generated by the sudden melting of the glacier killed twenty thousand people in the town of Armero. Moreover, the involvement of the local hydrothermal system has produced in the past phreatic and phreatomagmatic activity, as occurred in 1989. Therefore, the physico-chemical conditions of the hydrothermal system as well as its contribution to the shallow thermal groundwater and freshwater in terms of enthalpy and chemicals require a close monitoring. The phase of unrest occurred since 2010 and culminated with an eruption in 2012, after several years of relative stability, still maintains a moderate alert, as required by the high seismicity and SO2 degassing. In October 2013, a sampling campaign has been performed on thermal springs and stream water, located at 2600-5000 m of elevation on the slope of Nevado del Ruiz, analyzed for water chemistry and stable isotopes. Some of these waters are typically steam-heated (low pH and high sulfate content) by the vapour probably separating from a zoned hydrothermal system. By applying a model of steam-heating, based on mass and enthalpy balances, we have estimated the mass rate of hydrothermal steam discharging in the different springs. The composition of the hottest thermal spring (Botero Londono) is probably representative of a marginal part of the hydrothermal system, having a temperature of 250 °C and low salinity (Cl 1500 mg/l), which suggest, along with the retrieved isotope composition, a chiefly meteoric origin. The vapour discharged at the steam vent "Nereidas" (3600

  17. Boron geochemistry from some typical Tibetan hydrothermal systems: Origin and isotopic fractionation

    International Nuclear Information System (INIS)

    Zhang, Wenjie; Tan, Hongbing; Zhang, Yanfei; Wei, Haizhen; Dong, Tao

    2015-01-01

    The Tibetan plateau is characterized by intense hydrothermal activity and abnormal enrichment of trace elements in geothermal waters. Hydrochemistry and B isotope samples from geothermal waters in Tibet were systematically measured to describe the fractionation mechanisms and provide constraints on potential B reservoirs. B concentrations range from 0.35 to 171.90 mg/L, and isotopic values vary between −16.57 ‰ and +0.52 ‰. Geothermal fields along the Indus-Yarlung Zangbo suture zone and N–S rifts are observed with high B concentrations and temperatures. The similar hydrochemical compositions of high-B geothermal waters with magmatic fluid and consistent modeling of B isotopic compositions with present δ"1"1B values imply that the B in high-B geothermal waters is mainly contributed by magmatic sources, probably through magma degassing. In contrast, geothermal fields in other regions of the Lhasa block have relatively low B concentrations and temperatures. After considering the small fractionation factor and representative indicators of Na/Ca, Cl/HCO_3, Na + K and Si, the conformity between modeling results and the isotopic compositions of host rocks suggests that the B in low-temperature geothermal fields is mainly sourced from host rocks. According to simulated results, the B in some shallow geothermal waters not only originated from mixing of cold groundwater with deep thermal waters, but it was also contributed by equilibration with marine sedimentary rocks with an estimated proportion of 10%. It was anticipated that this study would provide useful insight into the sources and fractionation of B as well as further understanding of the relationships between B-rich salt lakes and geothermal activities in the Tibetan plateau. - Highlights: • Chemical and boron isotopic data of geothermal waters in Tibetan plateau were introduced. • Unusual enrichment of boron in Tibetan geothermal waters is related to magmatic and host rocks. • Boron

  18. Mixing of fluids in hydrothermal ore-forming (Sn,W) systems: stable isotope and rare earth elements data

    Science.gov (United States)

    Sushchevskaya, T. M.; Popova, J. A.; Velivetskaya, T. A.; Ignatiev, A. V.; Matveeva, S. S.; Limantseva, O. A.

    2012-04-01

    Experimental and physico-chemical modeling data witness to important role of mixing of different type of fluids during tin and tungsten ore formation in hydrothermal systems. Mixing of magmatogeneous fluids, exsolved from granite melts, with exogenic, initially meteoric waters in hydrothermal ore-forming systems may change chemical composition of ore-forming fluid, causing cassiterite and/or wolframite precipitation (Heinrich, 1990; Sushchevskaya, Ryzhenko, 2002). We studied the process of genetically different fluids mixing for two economic Sn-W deposits, situated in the Iultin ore region (North-East of Russia, Chukotka Penninsula). The Iultin and Svetloe deposits are located in the apical parts of close situated leucogranite stocks, formed at the final stage of the Iultin complex emplacement. Both deposits are composed of a series of quartz veins among the flyschoid rocks (T 1-2), cut by the dikes (K1) of lamprophyre, granodiorite porphyre and alpite. The veins of the deposits are dominated by the productive quartz-wolframite-cassiterite-arsenopyrite-muscovite mineral assemblage. Topaz, beryl, fluorite, and albite occur sporadically. The later sulfide (loellingite-stannite-chalcopyrite) and quartz-fluorite-calcite assemblages show insignificant development. The preore quartz veinlets in host hornfels contain disseminated iron sulfides, chalcopyrite, muscovite. Isotopic (H, O, Ar) study of minerals, supplemented by oxygen isotope data of host granites and metamorphic rocks gave us possibility to conclude, that at the Iultin and the Svetloye deposits fluid mixing was fixed on the early stages of deposit formation and could be regarded as probable cause of metal (W, Sn) precipitation. During postore time the intensive involvement of isotopically light exogenic waters have changed: a) the initial character of oxygen isotope zonality; b) the initial hydrogen isotope composition of muscovites, up to meteoric calculated values for productive fluid (while the δ18O

  19. Vapor Discharges On Nevado Del Ruiz During The Recent Activity: Clues On The Composition Of The Deep Hydrothermal System And Its Effects On Thermal Springs

    Science.gov (United States)

    Inguaggiato, S.; Federico, C.; Chacon, Z.; Londono, J. M.; Alzate, D. M.; Gil, E.

    2015-12-01

    The Nevado del ruiz volcano (NdR, 5321m asl), one of the most active in Colombia, threatens about 600,000 people. The existence of an ice cap and several streams channeling in some main rivers increase the risk of lahars and mudflows in case of unrest, as occurred during the November 1985 eruption, which caused 20,000 casualties. The involvement of the local hydrothermal system has also produced in the past phreatic and phreatomagmatic activity, as in 1985 and 1989. After more than 7 years of relative stability, since 2010, the still ongoing phase of unrest has produced two small eruption in 2012, and still maintains in high levels of seismicity and SO2 degassing. In October 2013, a sampling campaign has been performed on thermal springs and streamwater, located at 2600-5000 m asl, analyzed for water chemistry and stable isotopes. By applying a model of steam-heating, based on mass and enthalpy balances, we have estimated the mass rate of steam discharging in the different steam-heated springs. The composition of the hottest thermal spring (Botero Londoño) is probably representative of a marginal part of the hydrothermal system, having a temperature of 250°C and low salinity (Cl ~1500 mg/l), which suggest a chiefly meteoric origin, as also confirmed by the isotope composition retrieved for the hydrothermal water. The vapour discharged at the steam vent "Nereidas" (3600 m asl) is hypothesised to be separated from a high-temperature hyrothermal system. Based on its composition and on literature data on fluid inclusions, we have retrieved the P-T-X conditions of the deep hydrothermal system, as well as its pH and fO2. The vapour feeding Nereidas would separate from a byphasic hydrothermal system characterised by the follow parameters: t= 315°C, P=19 MPa, NaCl= 15 %, CO2 = 9%, and similar proportion between liquid and vapour. Considering also the equilibria involving S-bearing gases and HCl, we obtain pH=2, fO2 fixed by FeO-Fe2O3 buffer, and [Cl]=12000 mg/l. Changes

  20. A study of the relationship between cloud-to-ground lightning and precipitation in the convective weather system in China

    Directory of Open Access Journals (Sweden)

    Y. Zhou

    Full Text Available In this paper, the correlation between cloud-to-ground (CG lightning and precipitation has been studied by making use of the data from weather radar, meteorological soundings, and a lightning location system that includes three direction finders about 40 km apart from each other in the Pingliang area of east Gansu province in P. R. China. We have studied the convective systems that developed during two cold front processes passing over the observation area, and found that the CG lightning can be an important factor in the precipitation estimation. The regression equation between the average precipitation intensity (R and the number of CG lightning flashes (L in the main precipitation period is R = 1.69 ln (L - 0.27, and the correlation coefficient r is 0.86. The CG lightning flash rate can be used as an indicator of the formation and development of the convective weather system. Another more exhaustive precipitation estimation method has been developed by analyzing the temporal and spatial distributions of the precipitation relative to the location of the CG lightning flashes. Precipitation calculated from the CG lightning flashes is very useful, especially in regions with inadequate radar cover.

    Key words. Meteorology and atmospheric dynamics (atmospheric electricity; lightning; precipitation

  1. A high-latitude, low-latitude boundary layer model of the convection current system

    International Nuclear Information System (INIS)

    Siscoe, G.L.; Lotko, W.; Sonnerup, B.U.O.

    1991-01-01

    Observations suggest that both the high- and low-latitude boundary layers contribute to magnetospheric convection, and that their contributions are linked. In the interpretation pursued here, the high-latitude boundary layer (HBL) generates the voltage while the low-latitude boundary layer (LBL) generates the current for the part of the convection electric circuit that closes through the ionosphere. This paper gives a model that joins the high- and low-latitude boundary layers consistently with the ionospheric Ohm's law. It describes an electric circuit linking both boundary layers, the region 1 Birkeland currents, and the ionospheric Pedersen closure currents. The model works by using the convection electric field that the ionosphere receives from the HBL to determine two boundary conditions to the equations that govern viscous LBL-ionosphere coupling. The result provides the needed self-consistent coupling between the two boundary layers and fully specifies the solution for the viscous LBL-ionosphere coupling equations. The solution shows that in providing the current required by the ionospheric Ohm's law, the LBL needs only a tenth of the voltage that spans the HBL. The solution also gives the latitude profiles of the ionospheric electric field, parallel currents, and parallel potential. It predicts that the plasma in the inner part of the LBL moves sunward instead of antisunward and that, as the transpolar potential decreases below about 40 kV, reverse polarity (region 0) currents appear at the poleward border of the region 1 currents. A possible problem with the model is its prediction of a thin boundary layer (∼1000 km), whereas thicknesses inferred from satellite data tend to be greater

  2. Investigating Crustal Scale Fault Systems Controlling Volcanic and Hydrothermal Fluid Processes in the South-Central Andes, First Results from a Magnetotelluric Survey

    Science.gov (United States)

    Pearce, R.; Mitchell, T. M.; Moorkamp, M.; Araya, J.; Cembrano, J. M.; Yanez, G. A.; Hammond, J. O. S.

    2017-12-01

    At convergent plate boundaries, volcanic orogeny is largely controlled by major thrust fault systems that act as magmatic and hydrothermal fluid conduits through the crust. In the south-central Andes, the volcanically and seismically active Tinguiririca and Planchon-Peteroa volcanoes are considered to be tectonically related to the major El Fierro thrust fault system. These large scale reverse faults are characterized by 500 - 1000m wide hydrothermally altered fault cores, which possess a distinct conductive signature relative to surrounding lithology. In order to establish the subsurface architecture of these fault systems, such conductivity contrasts can be detected using the magnetotelluric method. In this study, LEMI fluxgate-magnetometer long-period and Metronix broadband MT data were collected at 21 sites in a 40km2 survey grid that surrounds this fault system and associated volcanic complexes. Multi-remote referencing techniques is used together with robust processing to obtain reliable impedance estimates between 100 Hz and 1,000s. Our preliminary inversion results provide evidence of structures within the 10 - 20 km depth range that are attributed to this fault system. Further inversions will be conducted to determine the approximate depth extent of these features, and ultimately provide constraints for future geophysical studies aimed to deduce the role of these faults in volcanic orogeny and hydrothermal fluid migration processes in this region of the Andes.

  3. Application of rain scanner SANTANU and transportable weather radar in analyze of Mesoscale Convective System (MCS) events over Bandung, West Java

    Science.gov (United States)

    Nugroho, G. A.; Sinatra, T.; Trismidianto; Fathrio, I.

    2018-05-01

    Simultaneous observation of transportable weather radar LAPAN-GMR25SP and rain-scanner SANTANU were conducted in Bandung and vicinity. The objective is to observe and analyse the weather condition in this area during rainy and transition season from March until April 2017. From the observation result reported some heavy rainfall with hail and strong winds occurred on March 17th and April 19th 2017. This events were lasted within 1 to 2 hours damaged some properties and trees in Bandung. Mesoscale convective system (MCS) are assumed to be the cause of this heavy rainfall. From two radar data analysis showed a more local convective activity in around 11.00 until 13.00 LT. This local convective activity are showed from the SANTANU observation supported by the VSECT and CMAX of the Transportable radar data that signify the convective activity within those area. MCS activity were observed one hour after that. This event are confirm by the classification of convective-stratiform echoes from radar data and also from the high convective index from Tbb Himawari 8 satellite data. The different MCS activity from this two case study is that April 19 have much more MCS activity than in March 17, 2017.

  4. The effect of the United States Great Lakes on the maintenance of derecho-producing mesoscale convective systems.

    Science.gov (United States)

    Bentley, M.; Sparks, J.; Graham, R.

    2003-04-01

    The primary aim of this research is to investigate the influence of the United States Great Lakes on the intensity of mesoscale convective systems (MCSs). One of the greatest nowcast challenges during the warm season is anticipating the impact of the Great Lakes on severe convection, particularly MCSs capable of producing damaging widespread windstorms known as derechos. Since a major derecho activity corridor lies over the Great Lakes region, it is important to understand the effects of the Lakes on the intensity and propagation of severe wind producing MCSs. Specific objectives of the research include: 1) The development of a short-term climatology of MCS events that have impacted the Great Lakes region over the past seven years; 2) An analysis of radar, satellite, surface (including buoy and lighthouse observations), and lake surface temperature data to determine the environmental conditions impacting the evolution of MCSs passing over a Great Lake; 3) An examination of MCS initiation times and seasonal frequencies of occurrence to delineate temporal consistencies in MCS evolution due to changing lake surface temperatures; and 4) The development of conceptual and forecast models to help anticipate MCS intensity and morphology as these systems interact with the Great Lakes environment.

  5. Thermal modeling of the forced convection Sandwich Greenhouse drying system for rubber sheets

    International Nuclear Information System (INIS)

    Tanwanichkul, B.; Thepa, S.; Rordprapat, W.

    2013-01-01

    Highlights: • Sandwich Greenhouse is designed for better quality and efficiency of rubber sheet drying. • Thermal models are developed to predict the convection heat transfer coefficient. • The models are validated and show good agreement with the actual experimental data. • The proposed greenhouse can maintain 40–60 °C, suitable for rubber sheet drying. • This greenhouse can bring down the moisture content to 2.8% in fewer than 2 days. - Abstract: In this paper, a novel “Sandwich Greenhouse” for rubber sheet drying is proposed. Using solar energy as the only heat source instead of traditional smoke house that requires firewood, it eliminates shortcomings such as skilled labor monitoring requirement, possible fire hazard, and darken-color rubber sheets due to soot particle contamination. Our greenhouse is specially designed to retain solar energy within, while minimizing the heat loss to the outside environment. The mathematical models are developed to predict the convection mass transfer coefficient and to study the thermal behavior during the drying of rubber sheets under our proposed greenhouse design. Validated with experimental observations, the models show good agreement with the actual experimental data. The experiment demonstrates an effectiveness of our proposed Sandwich Greenhouse, as the temperature of the rubber sheet is 15 °C and 5 °C higher than the ambient temperature during the daytime and nighttime, respectively. As a result, the moisture content of the rubber sheets can decrease from 36.4% to 2.8% in fewer than 2 days

  6. Hydrothermal growth and characterization of vertically well-aligned and dense ZnO nanorods on glass and silicon using a simple optimizer system

    Energy Technology Data Exchange (ETDEWEB)

    Mohammad, Sabah M., E-mail: Sabahaskari14@gmail.com; Ahmed, Naser M.; Abd-Alghafour, Nabeel M. [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), School of Physics, Universiti Sains Malaysia, Penang 11800 (Malaysia); Hassan, Z., E-mail: zai@usm.my [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), School of Physics, Universiti Sains Malaysia, Penang 11800 (Malaysia); CRI Natural Sciences, Universiti Sains Malaysia, Penang 11800 (Malaysia); Talib, Rawnaq A. [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), School of Physics, Universiti Sains Malaysia, Penang 11800 (Malaysia); Polymer Research Center, University of Basra (Iraq); Omar, A. F. [School of Physics, Universiti Sains Malaysia, Penang 11800 (Malaysia)

    2016-07-06

    Vertically, well-aligned and high density ZnO nanorods were successfully hydrothermally grown on glass and silicon substrates using a simple and low cost system. The mechanism of synthesis of ZnO nanorods, generated with our system under hydrothermal conditions, is investigated in this report. Field-emission scanning electron microscopy indicated that the fabricated ZnO nanorods on both substrates have hexagonal shape with diameters ranging from 20 nm to 70 nm which grew vertically from the substrate. XRD analysis confirms the formation of wurtzite ZnO phase with a preferred orientation along (002) direction perpendicular on the substrate and enhanced crystallinity. The low value of the tensile strain (0.126 %) revealed that ZnO nanorods preferred to grow along the c-axis for both substrates. Photoluminescence spectra exhibited a strong, sharp UV near band edge emission peak with narrow FWHM values for both samples.

  7. Hydrothermal growth and characterization of vertically well-aligned and dense ZnO nanorods on glass and silicon using a simple optimizer system

    International Nuclear Information System (INIS)

    Mohammad, Sabah M.; Ahmed, Naser M.; Abd-Alghafour, Nabeel M.; Hassan, Z.; Talib, Rawnaq A.; Omar, A. F.

    2016-01-01

    Vertically, well-aligned and high density ZnO nanorods were successfully hydrothermally grown on glass and silicon substrates using a simple and low cost system. The mechanism of synthesis of ZnO nanorods, generated with our system under hydrothermal conditions, is investigated in this report. Field-emission scanning electron microscopy indicated that the fabricated ZnO nanorods on both substrates have hexagonal shape with diameters ranging from 20 nm to 70 nm which grew vertically from the substrate. XRD analysis confirms the formation of wurtzite ZnO phase with a preferred orientation along (002) direction perpendicular on the substrate and enhanced crystallinity. The low value of the tensile strain (0.126 %) revealed that ZnO nanorods preferred to grow along the c-axis for both substrates. Photoluminescence spectra exhibited a strong, sharp UV near band edge emission peak with narrow FWHM values for both samples.

  8. Hydrothermal Liquefaction of Biomass

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.

    2010-12-10

    Hydrothermal liquefaction technology is describes in its relationship to fast pyrolysis of biomass. The scope of work at PNNL is discussed and some intial results are presented. HydroThermal Liquefaction (HTL), called high-pressure liquefaction in earlier years, is an alternative process for conversion of biomass into liquid products. Some experts consider it to be pyrolysis in solvent phase. It is typically performed at about 350 C and 200 atm pressure such that the water carrier for biomass slurry is maintained in a liquid phase, i.e. below super-critical conditions. In some applications catalysts and/or reducing gases have been added to the system with the expectation of producing higher yields of higher quality products. Slurry agents ('carriers') evaluated have included water, various hydrocarbon oils and recycled bio-oil. High-pressure pumping of biomass slurry has been a major limitation in the process development. Process research in this field faded away in the 1990s except for the HydroThermal Upgrading (HTU) effort in the Netherlands, but has new resurgence with other renewable fuels in light of the increased oil prices and climate change concerns. Research restarted at Pacific Northwest National Laboratory (PNNL) in 2007 with a project, 'HydroThermal Liquefaction of Agricultural and Biorefinery Residues' with partners Archer-Daniels-Midland Company and ConocoPhillips. Through bench-scale experimentation in a continuous-flow system this project investigated the bio-oil yield and quality that could be achieved from a range of biomass feedstocks and derivatives. The project was completed earlier this year with the issuance of the final report. HydroThermal Liquefaction research continues within the National Advanced Biofuels Consortium with the effort focused at PNNL. The bench-scale reactor is being used for conversion of lignocellulosic biomass including pine forest residue and corn stover. A complementary project is an international

  9. Mathematical modeling of flow in the working part of an acousto-convective drying system

    Science.gov (United States)

    Kravchenko, A. S.; Zhilin, A. A.; Fedorova, N. N.

    2018-03-01

    The objective of this study was to numerically simulate the nonstationary processes occurring in the acoustic-convective dryer (ACD) channel. In the present work, the problem was solved numerically in a three-dimensional formulation taking into account all features of the ACD duct in real geometry. The processes occurring in the ACD duct were simulated using the ANSYS Fluent 18.0 software. The numerical experiments provided an aggregate picture of the working gas flow in the ACD duct with the features near the subsonic nozzle and the cavity. The results of the numerical calculations were compared with experimental data. The best agreement with the experimental data was obtained for the viscosity model neglecting turbulent effects.

  10. Variability of oceanic deep convective system vertical structures observed by CloudSat in Indo-Pacific regions associated with the Madden-Julian oscillation

    Science.gov (United States)

    Yuan, Jian

    2016-09-01

    Vertical structures of deep convective systems during the Madden-Julian oscillation (MJO) are investigated using CloudSat radar measurements in Indo-Pacific oceanic areas. In active phases of the MJO, relatively more large systems and connected mesoscale convective systems (CMCSs) occur. The occurrence frequency of CMCSs peaks in the onset phase, a phase earlier than separated mesoscale convective systems (SMCSs). Compared with SMCSs, CMCSs of all sizes have weaker reflectivity above 8 km in their deep precipitating portions and thick anvil clouds closely linked to them, suggesting more "stratiform" physics associated with them. SMCSs and CMCSs together produce relatively the least anvil clouds in the onset phase, while their deep precipitating portions show stronger/weaker reflectivity above 8 km before/after the onset phase. Thus, after the onset phase of the MJO, mesoscale convective systems shift toward a more "convective" organization because SMCSs maximize after the onset, while their internal structures appear more stratiform because internally they have weaker reflectivity above 8 km. CMCSs coincide with a more humid middle troposphere spatially, even at the same locations a few days before they occur. Middle-tropospheric moistening peaks in the onset phase. Moistening of the free troposphere around deep convective systems shows relatively stronger moistening/drying below 700 hPa before/after the onset phase than domain-mean averages. Low-topped clouds occur most frequently around CMCSs and in active phases, consistent with the presence of a moister free troposphere. Coexistence of these phenomena suggests that the role of middle troposphere moisture in the formation of CMCSs should be better understood.

  11. Hydrothermal synthetic strategies of inorganic semiconducting nanostructures.

    Science.gov (United States)

    Shi, Weidong; Song, Shuyan; Zhang, Hongjie

    2013-07-07

    Because of their unique chemical and physical properties, inorganic semiconducting nanostructures have gradually played a pivotal role in a variety of research fields, including electronics, chemical reactivity, energy conversion, and optics. A major feature of these nanostructures is the quantum confinement effect, which strongly depends on their size, shape, crystal structure and polydispersity. Among all developed synthetic methods, the hydrothermal method based on a water system has attracted more and more attention because of its outstanding advantages, such as high yield, simple manipulation, easy control, uniform products, lower air pollution, low energy consumption and so on. Precise control over the hydrothermal synthetic conditions is a key to the success of the preparation of high-quality inorganic semiconducting nanostructures. In this review, only the representative hydrothermal synthetic strategies of inorganic semiconducting nanostructures are selected and discussed. We will introduce the four types of strategies based on exterior reaction system adjustment, namely organic additive- and template-free hydrothermal synthesis, organic additive-assisted hydrothermal synthesis, template-assisted hydrothermal synthesis and substrate-assisted hydrothermal synthesis. In addition, the two strategies based on exterior reaction environment adjustment, including microwave-assisted and magnetic field-assisted hydrothermal synthesis, will be also described. Finally, we conclude and give the future prospects of this research area.

  12. State and parameter estimation of spatiotemporally chaotic systems illustrated by an application to Rayleigh-Bénard convection.

    Science.gov (United States)

    Cornick, Matthew; Hunt, Brian; Ott, Edward; Kurtuldu, Huseyin; Schatz, Michael F

    2009-03-01

    Data assimilation refers to the process of estimating a system's state from a time series of measurements (which may be noisy or incomplete) in conjunction with a model for the system's time evolution. Here we demonstrate the applicability of a recently developed data assimilation method, the local ensemble transform Kalman filter, to nonlinear, high-dimensional, spatiotemporally chaotic flows in Rayleigh-Bénard convection experiments. Using this technique we are able to extract the full temperature and velocity fields from a time series of shadowgraph measurements. In addition, we describe extensions of the algorithm for estimating model parameters. Our results suggest the potential usefulness of our data assimilation technique to a broad class of experimental situations exhibiting spatiotemporal chaos.

  13. Continuous Data Assimilation for a 2D Bénard Convection System Through Horizontal Velocity Measurements Alone

    Science.gov (United States)

    Farhat, Aseel; Lunasin, Evelyn; Titi, Edriss S.

    2017-06-01

    In this paper we propose a continuous data assimilation (downscaling) algorithm for a two-dimensional Bénard convection problem. Specifically we consider the two-dimensional Boussinesq system of a layer of incompressible fluid between two solid horizontal walls, with no-normal flow and stress-free boundary conditions on the walls, and the fluid is heated from the bottom and cooled from the top. In this algorithm, we incorporate the observables as a feedback (nudging) term in the evolution equation of the horizontal velocity. We show that under an appropriate choice of the nudging parameter and the size of the spatial coarse mesh observables, and under the assumption that the observed data are error free, the solution of the proposed algorithm converges at an exponential rate, asymptotically in time, to the unique exact unknown reference solution of the original system, associated with the observed data on the horizontal component of the velocity.

  14. Statistical validation of the model of diffusion-convection (MDC) of 137Cs for the assessment of recent sedimentation rates in coastal systems

    International Nuclear Information System (INIS)

    Paulo Alves de Lima Ferreira; Eduardo Siegle; Michel Michaelovitch de Mahiques; Rubens Cesar Lopes Figueira; Carlos Augusto Franca Schettini

    2015-01-01

    This study aimed the validation of the model of diffusion-convection (MDC) of 137 Cs for the calculation of recent sedimentation rates in 13 sedimentary cores of two Brazilian coastal systems, the Cananeia-Iguape and Santos-Sao Vicente estuarine systems. The MDC covers key factors responsible for 137 Cs vertical migration in sediments: its diffusion to the interstitial water and the vertical convection of this water through the sediments. This study successfully validated the MDC use to determine sedimentation rates, which was statistically validated not only with 210 Pb xs (unsupported 210 Pb) models, widely used in oceanographic studies, but also by literature values for those regions. (author)

  15. Hydrothermal Diamond Anvil Cell Investigations Into the Alumina-Silica-Water System up to 1073 K and 4 GPa

    Science.gov (United States)

    Davis, M. K.; Stixrude, L. P.

    2004-12-01

    Understanding fluid chemistry in the subduction zone environment is key to unraveling the details of element transport from the slab to the surface. Solubility of different mineral assemblages in predominantly water-rich fluid along with pressure and temperature conditions control the chemical structure of the aqueous fluid and govern the transport opportunities for various chemical components away from the subducting slab. In-situ Raman experiments were performed in the alumina-silica-water system in an externally heated Bassett-type hydrothermal diamond anvil cell in the Department of Geological Sciences at the University of Michigan. Natural quartz samples (from the Owl Creek Mountains, Wyoming) were used as the silica source and synthetic ruby was used for the alumina source. Temperatures inside the diamond cell were monitored using type-K thermocouples wrapped around the diamonds and the pressure calibrated by the Raman shift of diamond or quartz or the fluorescence of ruby depending on conditions. Raman measurements of the aluminosilicate fluid show the presence of multiple alumina, silica, and mixed species. As predicted by calculations an aluminosilicate specie possibly of the form (HO)3SiOAl(OH)32- as well as the silica monomer and dimer specie were observed in the aluminosilicate fluid. There also appeared to be at least one hydrous alumina specie based on the presence of a Raman peaks at 228 cm-1, 339 cm-1 and 970 cm-1 in the fluid and a comparative analysis between Raman peaks in aqueous fluid in the silica-water, alumina-water, and alumina-silica-water systems. Solid phases formed during experiments (diaspore, kyanite) were confirmed with Raman spectroscopy.

  16. A molecular gut content study of Themisto abyssorum (Amphipoda) from Arctic hydrothermal vent and cold seep systems.

    Science.gov (United States)

    Olsen, Bernt Rydland; Troedsson, Christofer; Hadziavdic, Kenan; Pedersen, Rolf B; Rapp, Hans Tore

    2014-08-01

    The use of DNA as a marker for prey inside the gut of predators has been instrumental in further understanding of known and unknown interactions. Molecular approaches are in particular useful in unavailable environments like the deep sea. Trophic interactions in the deep sea are difficult to observe in situ, correct deep-sea experimental laboratory conditions are difficult to obtain, animals rarely survive the sampling, or the study organisms feed during the sampling due to long hauls. Preliminary studies of vent and seep systems in the Nordic Seas have identified the temperate-cold-water pelagic amphipod Themisto abyssorum as a potentially important predator in these chemosynthetic habitats. However, the prey of this deep-sea predator is poorly known, and we applied denaturing high performance liquid chromatography (DHPLC) to investigate the predator-prey interactions of T. abyssorum in deep-water vent and seep systems. Two deep-water hydrothermally active localities (The Jan Mayen and Loki's Castle vent fields) and one cold seep locality (The Håkon Mosby mud volcano) in the Nordic Seas were sampled, genomic DNA of the stomachs of T. abyssorum was extracted, and 18S rDNA gene was amplified and used to map the stomach content. We found a wide range of organisms including micro-eukaryotes, metazoans and detritus. Themisto abyssorum specimens from Loki's Castle had the highest diversity of prey. The wide range of prey items found suggests that T. abyssorum might be involved in more than one trophic level and should be regarded as an omnivore and not a strict carnivore as have previously been suggested. © 2013 John Wiley & Sons Ltd.

  17. Caldera processes and magma-hydrothermal systems continental scientific drilling program: thermal regimes, Valles caldera research, scientific and management plan

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.; Nielson, D.L. (eds.)

    1986-05-01

    Long-range core-drilling operations and initial scientific investigations are described for four sites in the Valles caldera, New Mexico. The plan concentrates on the period 1986 to 1993 and has six primary objectives: (1) study the origin, evolution, physical/chemical dynamics of the vapor-dominated portion of the Valles geothermal system; (2) investigate the characteristics of caldera fill and mechanisms of caldera collapse and resurgence; (3) determine the physical/chemical conditions in the heat transfer zone between crystallizing plutons and the hydrothermal system; (4) study the mechanism of ore deposition in the caldera environment; (5) develop and test high-temperature drilling techniques and logging tools; and (6) evaluate the geothermal resource within a large silicic caldera. Core holes VC-2a (500 m) and VC-2b (2000 m) are planned in the Sulphur Springs area; these core holes will probe the vapor-dominated zone, the underlying hot-water-dominated zone, the boiling interface and probable ore deposition between the two zones, and the deep structure and stratigraphy along the western part of the Valles caldera fracture zone and resurgent dome. Core hole VC-3 will involve reopening existing well Baca number12 and deepening it from 3.2 km (present total depth) to 5.5 km, this core hole will penetrate the deep-crystallized silicic pluton, investigate conductive heat transfer in that zone, and study the evolution of the central resurgent dome. Core hole VC-4 is designed to penetrate deep into the presumably thick caldera fill in eastern Valles caldera and examine the relationship between caldera formation, sedimentation, tectonics, and volcanism. Core hole VC-5 is to test structure, stratigraphy, and magmatic evolution of pre-Valles caldera rocks, their relations to Valles caldera, and the influences of regional structure on volcanism and caldera formation.

  18. Study of the heat transfers spectral radiation - conduction - natural convection in hybrid photovoltaic systems for buildings

    International Nuclear Information System (INIS)

    Muresan, C.

    2005-01-01

    numerical solution of the Radiative Transfer Equation in diffused part in the case of a mono-dimensional plane geometry. The directional discretizations of each layer are selected in such a way that the discrete directions of one of the layers correspond to those refracted of the close layer and this makes it possible to avoid the use of approximations related to non coincidence of the discrete directions of a layer with those refracted by the close layer. Directional quadratures are then established in an adaptive way in each layer and for each spectral frequency. The results obtained are validated by an approach of Monte Carlo type. The coupling of this model with a Low Reynolds number RANS model will be carried out. This will be done in order to study the convective heat transfers in natural convection for configurations of double facade integration under consideration within the framework of PRI CNRS. The comparison of this model is carried out for experimental configurations of vertical channel type uniformly heated in natural convection. The prospects for this stage are multiple and consist of analyzing the influence of the mode of flow on the thermal pulling of the hybrid components, the effects of the positioning of modules statement, the air gap between the two frontages and the boundary conditions thermal generated by the modules. Lastly, in order to supplement the energy balance of such components and more particularly that governs the thermal behavior of a photosensitive cell, the electric phenomenon of conversion is approached in adequacy with the level of modeling of the coupled thermal transfers radiation - conduction within a PV component. To carry this out, we can consider the local power of spectral radiation absorbed and converted into electric output. (author)

  19. National Convective Weather Diagnostic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current convective hazards identified by the National Convective Weather Detection algorithm. The National Convective Weather Diagnostic (NCWD) is an automatically...

  20. Linking Spectral Features with Composition, Crystallinity, and Roughness Properties of Silica and Implications for Candidate Hydrothermal Systems on Mars

    Science.gov (United States)

    Hamilton, V. E.; McDowell, M. L.; Berger, J. A.; Cady, S. L.; Knauth, L. P.

    2011-12-01

    We have collected visible to near infrared reflectance (VNIR, ~0.4 - 2.5 um), thermal infrared emissivity (TIR, ~5 - 45 um), SEM, XRD, surface roughness, and petrographic data for 18 silica samples. These rocks (e.g., replacement chert, geyserite, opal-A/-CT) represent a variety of geologic formation environments, including hydrothermal, and have XRD-determined crystallinities ranging from 10 according to the quartz crystallinity index. Our findings are relevant to the interpretation of orbital and in situ spectral observations of crystalline or amorphous silica on the Martian surface, some of which may have formed in hydrothermal systems. Almost all of our samples' VNIR spectra contain discernible bands. The most common features are related to hydration (H2O and/or OH) of silica (e.g., at ~1.4, 1.9, and 2.2 um). The visibility and strength of these bands is not always constant between spectra from different areas of a sample. Other features include those of carbonate, phyllosilicate, and iron oxide impurities. All of our amorphous silica samples have hydration features in the VNIR, but we note that the absorptions around ~2.2 um can be very weak in amorphous samples relative to features at other wavelengths and relative to ~2.2-um features observed in Martian data, suggesting that some amorphous silica on Mars could go undetected. Deposits containing significant anhydrous, crystalline silica (chert) may be assumed to lack features in the VNIR, but many of our cherts have spectral features and could be misidentified as materials dominated by what is a minor contaminant. Thermal infrared spectra of chert and opaline silica differ from each other as a result of the loss of long-range Si-O order in increasingly amorphous samples. Our samples display a clear trend in TIR band shapes where features attributable to crystalline quartz and amorphous silica are blended in samples with intermediate crystallinities. Most diagnostic TIR spectral features observable in

  1. Hydrogeologic controls on saturation profiles in heat-pipe-like hydrothermal systems: numerical study

    Science.gov (United States)

    Pervin, Mollika; Ghergut, Iulia; Graf, Thomas; Peche, Aaron

    2016-04-01

    Most geothermal reservoirs are of the liquid-dominated type, and their unexploited-state pressure profile approximately follows the hydrostatic gradient. In very hot liquid-dominated systems, temperature typically follows a boiling-point-for-depth (BPD) relationship. By contrast, vapor-dominated systems exhibit (in their unexploited state) surprisingly small vertical gradients of temperature and pressure, such that a constantly high temperature is encountered over a large vertical thickness, while their pressure approximately follows vapour pressure, pvap(T°). This implies that (Pruess 1985, Truesdell and White 1973): (i) for a vapor-dominated reservoir to exist, it must be sealed laterally - otherwise it would be flooded by neighboring groundwaters with hydrostatic p profile, and (ii) liquid water should somehow be present in the whole system - otherwise p values would not be constrained by the pvap(T°) relationship for water. Historically, one of the most puzzling aspects of vapor-dominated systems was the large amount of heat flowing upwards, while vertical T° gradients remained negligible. This mechanism was deemed as 'heat pipe'(HP) (Eastman 1968): In the central zone of a vapor-dominated system, both vapor and liquid are mobile; vapor flows upwards, condenses at shallower depth, and the liquid condensate flows downwards. Due to the large amount of latent enthalpy released in vapor condensation, the vapor-liquid counter-flow can generate large rates of heat flow with negligible net mass transport (Pruess 1985). In order to be able to exploit two-phase (including vapor-dominated) reservoirs in a sustainable manner, one first needs to understand the conditions under which a two-phase (or a vapor-dominated) system has evolved naturally, and which have led to its present (quasi-) steady undisturbed state. Past studies have found that HP can exist in two distinct states, corresponding to liquid-dominated and vapor-dominated p profiles, respectively. Within this

  2. Comparative analysis of cost benefit division methodologies in a hydrothermal generation system

    International Nuclear Information System (INIS)

    Pereira, M.V.F.; Gorenstin, B.G.; Campodonico, N.M.; Costa, J.P. da; Kelman, J.

    1989-01-01

    The development and operation planning of the Brazilian generation system has been realized in a coordinate way by several years, due to some organizations, where the main generating companies from the country take part. The benefit share of the system to each participant of the planning and integrated operation has aroused interest. This paper describes the alternate forms of cost benefit allocation, between the participant companies of a coordinate operation, in order to reach an adequateness of remuneration and incentives. It was analysed two proposal of benefit allocation for energy export/import contracts: share by generation value and share by marginal benefit, concluding that the second one represents the best way of contribution for the several factors that comprising a hydroelectric power plant (storage capacity, effective storage and turbine capacity). (C.G.C.). 1 tab

  3. An enhanced artificial bee colony algorithm (EABC) for solving dispatching of hydro-thermal system (DHTS) problem.

    Science.gov (United States)

    Yu, Yi; Wu, Yonggang; Hu, Binqi; Liu, Xinglong

    2018-01-01

    The dispatching of hydro-thermal system is a nonlinear programming problem with multiple constraints and high dimensions and the solution techniques of the model have been a hotspot in research. Based on the advantage of that the artificial bee colony algorithm (ABC) can efficiently solve the high-dimensional problem, an improved artificial bee colony algorithm has been proposed to solve DHTS problem in this paper. The improvements of the proposed algorithm include two aspects. On one hand, local search can be guided in efficiency by the information of the global optimal solution and its gradient in each generation. The global optimal solution improves the search efficiency of the algorithm but loses diversity, while the gradient can weaken the loss of diversity caused by the global optimal solution. On the other hand, inspired by genetic algorithm, the nectar resource which has not been updated in limit generation is transformed to a new one by using selection, crossover and mutation, which can ensure individual diversity and make full use of prior information for improving the global search ability of the algorithm. The two improvements of ABC algorithm are proved to be effective via a classical numeral example at last. Among which the genetic operator for the promotion of the ABC algorithm's performance is significant. The results are also compared with those of other state-of-the-art algorithms, the enhanced ABC algorithm has general advantages in minimum cost, average cost and maximum cost which shows its usability and effectiveness. The achievements in this paper provide a new method for solving the DHTS problems, and also offer a novel reference for the improvement of mechanism and the application of algorithms.

  4. An enhanced artificial bee colony algorithm (EABC for solving dispatching of hydro-thermal system (DHTS problem.

    Directory of Open Access Journals (Sweden)

    Yi Yu

    Full Text Available The dispatching of hydro-thermal system is a nonlinear programming problem with multiple constraints and high dimensions and the solution techniques of the model have been a hotspot in research. Based on the advantage of that the artificial bee colony algorithm (ABC can efficiently solve the high-dimensional problem, an improved artificial bee colony algorithm has been proposed to solve DHTS problem in this paper. The improvements of the proposed algorithm include two aspects. On one hand, local search can be guided in efficiency by the information of the global optimal solution and its gradient in each generation. The global optimal solution improves the search efficiency of the algorithm but loses diversity, while the gradient can weaken the loss of diversity caused by the global optimal solution. On the other hand, inspired by genetic algorithm, the nectar resource which has not been updated in limit generation is transformed to a new one by using selection, crossover and mutation, which can ensure individual diversity and make full use of prior information for improving the global search ability of the algorithm. The two improvements of ABC algorithm are proved to be effective via a classical numeral example at last. Among which the genetic operator for the promotion of the ABC algorithm's performance is significant. The results are also compared with those of other state-of-the-art algorithms, the enhanced ABC algorithm has general advantages in minimum cost, average cost and maximum cost which shows its usability and effectiveness. The achievements in this paper provide a new method for solving the DHTS problems, and also offer a novel reference for the improvement of mechanism and the application of algorithms.

  5. Stable Isotope Geochemistry of Extremely Well-Preserved 2.45-Billion-Year-Old Hydrothermal Systems in the Vetreny Belt, Baltic Shield: Insights into Paleohydrosphere

    Science.gov (United States)

    Zakharov, D. O.; Bindeman, I. N.

    2015-12-01

    The early Paleoproterozoic was an eventful period in the Earth's history. The first portions of free oxygen emerged in the atmosphere, Snowball Earth glaciations happened several times and the first supercontinent broke up due to extensive rifting. These events should have affected the stable isotopic composition of the hydrosphere. In this study, we use rocks that were altered in underwater hydrothermal systems to investigate the stable isotopic composition of the hydrosphere 2.39-2.45 billion years ago (hereinafter, Ga). Extremely low-δ18O (down to -27.5‰ SMOW) rocks from 2.39 Ga metamorphosed subglacial hydrothermal systems of the Belomorian belt, Baltic Shield formed at near-equatorial latitudes suggesting a Snowball (or Slushball) Earth glaciation. These results motivated us to look at temporally and geographically close hydrothermal systems from the unmetamorhposed 2.45 Ga Vetreny Belt rift. The length of the rift is 250 km and it is composed of high-Mg basalts, mafic-ultramafic intrusions and sedimentary successions. We examined several localities of high-Mg basalt flows that include astonishingly fresh pillow lavas, often with preserved volcanic glass, eruptive breccias, and hydrothermal alteration zones. Collected samples serve a great textural evidence of water-rock interaction that occurred in situ while basalts were cooling. The preliminary results from coexisting quartz and epidote (T, D18O=311°C), and from coexisting calcite and quartz (T, D18O=190°C) yield values of δ18O of involved water between -1.6 and -0.9 ‰. The values of δ13C in calcites vary between -4.0 and -2.3 ‰. It is likely that hydrothermal fluids operated in the Vetreny Belt rift were derived from seawater that is no different from modern oceanic water in terms of δ18O. Apparently, the rift was a Paleoproterozoic analog of the modern Red Sea, filled with oceanic water. The result is important because the Vetreny Belt rift predates the onset of Snowball Earth glaciation at 2

  6. Microbial Diversity of Carbonate Chimneys at the Lost City Hydrothermal Field: Implications for Life-Sustaining Systems in Peridotite Seafloor Environments

    Science.gov (United States)

    Schrenk, M. O.; Cimino, P.; Kelley, D. S.; Baross, J. A.

    2002-12-01

    The Lost City Hydrothermal Field (LCHF) is a novel peridotite-hosted vent environment discovered in Dec. 2000 at 30 N near the Mid-Atlantic Ridge. This field contains multiple large (up to 60 m), carbonate chimneys venting high pH (9-10), moderate temperature (45-75 C) fluids. The LCHF is unusual in that it is located on 1.5 my-old oceanic crust, 15 km from the nearest spreading axis. Hydrothermal flow in this system is believed to be driven by exothermic serpentinization reactions involving iron-bearing minerals in the underlying seafloor. The conditions created by such reactions, which include significant quantities of dissolved methane and hydrogen, create habitats for microbial communities specifically adapted to this unusual vent environment. Ultramafic, reducing hydrothermal environments like the LCHF may be analogous to geologic settings present on the early Earth, which have been suggested to be important for the emergence of life. Additionally, the existence of hydrothermal environments far away from an active spreading center expands the range of potential life-supporting environments elsewhere in the solar system. To study the abundance and diversity of microbial communities inhabiting the environments that characterize the LCHF, carbonate chimney samples were analyzed by microscopic and molecular methods. Cell densities of between 105 and 107 cells/g were observed within various samples collected from the chimneys. Interestingly, 4-11% of the microbial population in direct contact with vent fluids fluoresced with Flavin-420, a key coenzyme involved in methanogenesis. Enrichment culturing from chimney material under aerobic and anaerobic conditions yielded microorganisms in the thermophilic and mesophilic temperature regimes in media designed for methanogenesis, methane-oxidation, and heterotrophy. PCR analysis of chimney material indicated the presence of both Archaea and Eubacteria in the carbonate samples. SSU rDNA clone libraries constructed from the

  7. Momentum, heat, and neutral mass transport in convective atmospheric pressure plasma-liquid systems and implications for aqueous targets

    Science.gov (United States)

    Lindsay, Alexander; Anderson, Carly; Slikboer, Elmar; Shannon, Steven; Graves, David

    2015-10-01

    There is a growing interest in the study of plasma-liquid interactions with application to biomedicine, chemical disinfection, agriculture, and other fields. This work models the momentum, heat, and neutral species mass transfer between gas and aqueous phases in the context of a streamer discharge; the qualitative conclusions are generally applicable to plasma-liquid systems. The problem domain is discretized using the finite element method. The most interesting and relevant model result for application purposes is the steep gradients in reactive species at the interface. At the center of where the reactive gas stream impinges on the water surface, the aqueous concentrations of OH and ONOOH decrease by roughly 9 and 4 orders of magnitude respectively within 50 μ m of the interface. Recognizing the limited penetration of reactive plasma species into the aqueous phase is critical to discussions about the therapeutic mechanisms for direct plasma treatment of biological solutions. Other interesting results from this study include the presence of a 10 K temperature drop in the gas boundary layer adjacent to the interface that arises from convective cooling. Though the temperature magnitudes may vary among atmospheric discharge types (different amounts of plasma-gas heating), this relative difference between gas and liquid bulk temperatures is expected to be present for any system in which convection is significant. Accounting for the resulting difference between gas and liquid bulk temperatures has a significant impact on reaction kinetics; factor of two changes in terminal aqueous species concentrations like H2O2, NO2- , and NO3- are observed in this study if the effect of evaporative cooling is not included.

  8. Experimental analysis of the natural convection system through a closed loop under transient regime

    International Nuclear Information System (INIS)

    Lavrador, Marcelo de Bastos; Braga, Carlos Valois Maciel; Carajilescov, Pedro

    1996-01-01

    This work presents the experimental model used in the study of closed loop natural convection (thermosyphons). Details of the main circuit and information on the used instrumentation are also presented. The study aimed the circuit thermal performance, initially justifying the oscillatory behaviour of the time vs. temperature curves. As expected, the curves for the cold leg presented an oscillation amplitude lesser than those for hot leg since the 'peaks' which reveal high temperature spots disappear due to the heat transfer to the cooling water. Those curves were not influenced within the measured range, by the changes occurred in the cooling water flow (secondary circuit). Besides, when varying the power supplied by the hot source it was observed a variation directly proportional of the oscillation frequency, of the oscillation amplitude, and the difference between the hot and cold legs temperatures. Concerning to the forced power variations, it is observed that the oscillation is always restarted and the final results are related to the second applied power

  9. A forced convective heat transfer model for two-phase hydrogen systems

    International Nuclear Information System (INIS)

    Pasch, J.; Anghaie, S.

    2007-01-01

    A consistent event in the use of hydrogen in nuclear thermal propulsion is film boiling, in which the wall heat is so large that liquid can not exist at the wall. Instead, vapor interfaces with the wall and liquid flows in the core of the duct. To better understand heat transfer under these conditions, a select set of hydrogen test data from these conditions are analyzed. This paper presents the results of an extensive literature search for film boiling heat transfer models. A representative cross-section of these models is then applied to the data. The heat transfer coefficient data were found difficult to predict and highly dependent upon the flow regime. Pre-critical heat flux correlations completely fail to predict the heat transfer of inverted film boiling conditions. Pool boiling models for inverted film boiling also are inappropriate. Current force convection models for inverted film boiling, while far better than the previous two classes of models, still generate large predictive errors. It is recommended that for the inverted annular film boiling flow regime the modified equilibrium bulk Dittus-Boelter model be used. For agitated inverted annular film boiling and dispersed film boiling regimes associated with positive equilibrium qualities, the Hendricks model should be used. (A.C.)

  10. Medusa-Isosampler: A modular, network-based observatory system for combined physical, chemical and microbiological monitoring, sampling and incubation of hydrothermal and cold seep fluids

    Science.gov (United States)

    Schultz, A.; Flynn, M.; Taylor, P.

    2004-12-01

    The study of life in extreme environments provides an important context from which we can undertake the search for extraterrestrial life, and through which we can better understand biogeochemical feedback in terrestrial hydrothermal and cold seep systems. The Medusa-Isosampler project is aimed at fundamental research into understanding the potential for, and limits to, chemolithoautotrophic life, i.e. primary production without photosynthesis. One environment that might foster such life is associated with the high thermal and chemical gradient environment of hydrothermal vent structures. Another is associated with the lower thermal and chemical gradient environment of continental margin cold seeps. Under NERC, NASA and industrial support, we have designed a flexible instrumentation system, operating as networked, autonomous modules on a local area network, that will make possible simultaneous physical and chemical sampling and monitoring of hydrothermal and cold seep fluids, and the in situ and laboratory incubation of chemosynthetic microbes under high pressure, isobaric conditions. The system has been designed with long-term observatory operations in mind, and may be reconfigured dynamically as the requirements of the observatory installation change. The modular design will also accommodate new in situ chemical and biosensor technologies, provided by third parties. The system may be configured for seafloor use, and can be adapted to use in IODP boreholes. Our overall project goals are provide an instrumentation system capable of probing both high and low-gradient water-rock systems for chemolithoautotrophic biospheres, to identify the physical and chemical conditions that define these microhabitats and explore the details of the biogeochemical feedback loops that mediate these microhabitats, and to attempt to culture and identify chemolithoautotrophic microbial communities that might exist there. The Medusa-Isosampler system has been produced and is now

  11. Transfer and partitioning of energy and mass through seafloor hydrothermal systems: comparative studies at the Ridge2000 Integrated Study Sites (ISS) (Invited)

    Science.gov (United States)

    Tivey, M. K.

    2010-12-01

    Seafloor hydrothermal systems are major players in the transfer of mass and energy from the mantle and crust to the ocean and biosphere. Over the past thirty years, much has been learned about this transfer to the ocean, but considerably less is known about the transfer to the biosphere. Study of hydrothermal systems in a diverse range of geologic settings has shown relationships between spreading rate and hydrothermal heat flux, substrate composition (including rock geochemistry, presence/absence of sediment) and hydrothermal fluid composition, and magmatic/tectonic events and temporal variability of fluid composition (e.g., German and Von Damm, Treatise On Geochemistry, 2004; Baker et al. AGU Monograph Series 91, 1995). Studies in arc and back-arc settings are documenting the effects of magmatic acid volatiles on fluid-rock reaction and fluid and vent deposit compositions (e.g., Ishibashi and Urabe, Backarc Basins: Tectonics and Magmatism, 1995). These comparative studies in a wide range of geologic settings, including at the three Ridge2000 ISS, have provided a fairly good understanding of the flux of heat and many elements to the ocean associated with high temperature seafloor hydrothermal systems. Considerably less is known, however, about the partitioning of heat and mass (particularly metals and sulfur) in hydrothermal systems. The deposits that form at vent sites are intimately linked within paths of energy and mass transport from the mantle and crust to the oceans. Transport differs greatly through different types of deposits (e.g., black smokers, white smokers/diffusers, flanges). Estimates of heat flux from measured temperatures of flow (unless integrated over and around an entire vent field) require an understanding of the partitioning of flow between focused black smokers and more diffuse flow from diffusers, flanges, and surfaces of deposits, and from the igneous substrate. Estimates of mass flux into the ocean require an understanding of the

  12. Probabilistic analysis of fuel consumption in the hydrothermal system with marginal fixation of tariffs

    International Nuclear Information System (INIS)

    Alarcon A, I.; Olmedo H, J.C.

    1989-01-01

    A simulation model, that determining the distribution function of the coal consumption from Chile Thermal Stations was developed, consisting in a tool for taking of a decision of coal purchase from Chilectra Generation Stations. It was applied for analysing the probable coal consumption for the year of 1990. A sensitivity analysis over the main variables, that reflecting in these consumption was also included. This model only makes a monthly energy balance, therefore to achieve a best fuel consumption estimation, it should be included, in the second development stage, a energy balance for the peak hours of the system. (C.G.C.). 2 refs, 4 figs, 5 tabs

  13. Experiments Using a Ground-Based Electrostatic Levitator and Numerical Modeling of Melt Convection for the Iron-Cobalt System in Support of Space Experiments

    Science.gov (United States)

    Lee, Jonghyun; SanSoucie, Michael P.

    2017-08-01

    Materials research is being conducted using an electromagnetic levitator installed in the International Space Station. Various metallic alloys were tested to elucidate unknown links among the structures, processes, and properties. To accomplish the mission of these space experiments, several ground-based activities have been carried out. This article presents some of our ground-based supporting experiments and numerical modeling efforts. Mass evaporation of Fe50Co50, one of flight compositions, was predicted numerically and validated by the tests using an electrostatic levitator (ESL). The density of various compositions within the Fe-Co system was measured with ESL. These results are being served as reference data for the space experiments. The convection inside a electromagnetically-levitated droplet was also modeled to predict the flow status, shear rate, and convection velocity under various process parameters, which is essential information for designing and analyzing the space experiments of some flight compositions influenced by convection.

  14. Reconstructing Magmatic-Hydrothermal Systems via Geologic Mapping of the Tilted, Cross-sectional Exposures of the Yerington District, Nevada

    Science.gov (United States)

    Dilles, J. H.; Proffett, J. M.

    2011-12-01

    The Jurassic Yerington batholith was cut by Miocene to recent normal faults and tilted ~90° west (Proffett, 1977). Exposures range from the volcanic environment to ~6 km depth in the batholith. Magmatic-hydrothermal fluids derived from the Luhr Hill granite and associated porphyry dikes produced characteristic porphyry copper mineralization and rock alteration (K-silicate, sericitic, and advanced argillic) in near-vertical columnar zones above cupolas on the deep granite. In addition, saline brines derived from the early Mesozoic volcanic and sedimentary section intruded by the batholith were heated and circulated through the batholith producing voluminous sodic-calcic and propylitic alteration. The magnetite-copper ore body at Pumpkin Hollow is hosted in early Mesozoic sedimentary rocks in the contact aureole of the batholith, and appears to be an IOCG type deposit produced where the sedimentary brines exited the batholith. Although many advances in understanding of Yerington have been made by lab-based geochronology and geochemistry studies, the first order igneous and hydrothermal features were recognized first in the 1960s and 1970s and are best documented by geological mapping at a variety of scales ranging from 1:500 to 1:24,000. The Anaconda technique of mapping mine benches, trenches, and drill cores was perfected here (Einaudi, 1997), and other techniques were used for surface exposures. The geologic and hydrothermal alteration maps establish that hydrothermal alteration accompanied each of several porphyry dike intrusions, and affected more than 100 km3 of rock. Both zonation in alteration mineralogy and vein orientations allow reconstruction of source areas and >5 km-long flow-paths of hydrothermal fluids through the batholith and contact aureole.

  15. A new formulation of the equivalent thermal in optimization of hydrothermal systems

    Directory of Open Access Journals (Sweden)

    Bayón L.

    2002-01-01

    Full Text Available In this paper, we revise the classical formulation of the problem depriving it of the concepts that are superfluous from the mathematical point of view. We observe that a number of power stations can be substituted by a single one that behaves equivalently to the entire set. Proceeding in this way, we obtain a variational formulation in its purest sense (without restrictions. This formulation allows us to employ the theory of calculus of variations to the highest degree. We then calculate the equivalent minimizer in the case where the cost functions are second-order polynomials. We prove that the equivalent minimizer is a second-order polynomial with piece-wise constant coefficients. Moreover, it belongs to the class C 1 . Finally, we present various examples prompted by real systems and perform the proposed algorithms using Mathematica.

  16. 3D Geothermal Modelling of the Mount Amiata Hydrothermal System in Italy

    Directory of Open Access Journals (Sweden)

    Paolo Fulignati

    2014-11-01

    Full Text Available In this paper we build a subsurface model that helps in visualizing and understanding the structural framework, geology and their interactions with the Mt. Amiata geothermal system. Modelling in 3D provides the possibility to interpolate the geometry of structures and is an effective way of understanding geological features. The 3D modelling approach appears to be crucial for further progress in the reconstruction of the assessment of the geothermal model of Mt. Amiata. Furthermore, this model is used as the basis of a 3D numerical thermo-fluid-dynamic model of the existing reservoir(s. The integration between borehole data and numerical modelling results allows reconstructing the temperature distribution in the subsoil of the Mt. Amiata area.

  17. Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms

    Science.gov (United States)

    Shanks, W. C., III; Böhlke, J. K.; Seal, R. R., II

    Studies of abundance variations of light stable isotopes in nature have had a tremendous impact on all aspects of geochemistry since the development, in 1947, of a gas source isotope ratio mass spectrometer capable of measuring small variations in stable isotope ratios [Nier, 1947] Stable isotope geochemistry is now a mature field, as witnessed by the proliferation of commercially available mass spectrometers installed at virtually every major academic, government, and private-sector research geochemistry laboratory. A recent search of a literature database revealed over 3,000 articles that utilized stable isotope geochemistry over the last 20 years. Nonetheless, many exciting new technical developments are leading to exciting new discoveries and applications. In particular, micro analytical techniques involving new generations of laser- and ion-microprobes are revolutionizing the types of analyses that can be done on spot sizes as small as a few tens of micrometers [Shanks and Criss, 1989]. New generations of conventional gas source and thermal ionization mass spectrometers, with high levels of automation and increased sensitivity and precision, are allowing analyses of large numbers of samples, like those needed for stable isotope stratigraphy in marine sediments, and are enabling the development and application of new isotopic systems.

  18. The Dependence of Convective Core Overshooting on Stellar Mass: Additional Binary Systems and Improved Calibration

    Science.gov (United States)

    Claret, Antonio; Torres, Guillermo

    2018-06-01

    Many current stellar evolution models assume some dependence of the strength of convective core overshooting on mass for stars more massive than 1.1–1.2 M ⊙, but the adopted shapes for that relation have remained somewhat arbitrary for lack of strong observational constraints. In previous work, we compared stellar evolution models to well-measured eclipsing binaries to show that, when overshooting is implemented as a diffusive process, the fitted free parameter f ov rises sharply up to about 2 M ⊙, and remains largely constant thereafter. Here, we analyze a new sample of eight binaries selected to be in the critical mass range below 2 M ⊙ where f ov is changing the most, nearly doubling the number of individual stars in this regime. This interval is important because the precise way in which f ov changes determines the shape of isochrones in the turnoff region of ∼1–5 Gyr clusters, and can thus affect their inferred ages. It also has a significant influence on estimates of stellar properties for exoplanet hosts, on stellar population synthesis, and on the detailed modeling of interior stellar structures, including the calculation of oscillation frequencies that are observable with asteroseismic techniques. We find that the derived f ov values for our new sample are consistent with the trend defined by our earlier determinations, and strengthen the relation. This provides an opportunity for future series of models to test the new prescription, grounded on observations, against independent observations that may constrain overshooting in a different way.

  19. Geothermal Heating, Convective Flow and Ice Thickness on Mars

    Science.gov (United States)

    Rosenberg, N. D.; Travis, B. J.; Cuzzi, J.

    2001-01-01

    Our 3D calculations suggest that hydrothermal circulation may occur in the martian regolith and may significantly thin the surface ice layer on Mars at some locations due to the upwelling of warm convecting fluids driven solely by background geothermal heating. Additional information is contained in the original extended abstract.

  20. Concepts of magnetospheric convection

    International Nuclear Information System (INIS)

    Vasyliunas, V.M.

    1975-01-01

    Magnetospheric physics, which grew out of attempts to understand the space environment of the Earth, is becoming increasingly applicable to other systems in the Universe. Among the planets, in addition to the Earth, Jupiter, Mercury, Mars and (in a somewhat different way) Venus are now known to have magnetospheres. The magnetospheres of pulsars have been regarded as an essential part of the pulsar phenomenon. Other astrophysical systems, such as supernova remnant shells or magnetic stars and binary star systems, may be describable as magnetospheres. The major concepts of magnetospheric physics thus need to be formulated in a general way not restricted to the geophysical context in which they may have originated. Magnetospheric convection has been one of the most important and fruitful concepts in the study of the Earth's magnetosphere. This paper describes the basic theoretical notions of convection in a manner applicable to magnetospheres generally and discusses the relative importance of convective corotational motions, with particular reference to the comparison of the Earth and Jupiter. (Auth.)

  1. 2D and 3D thermal simulations for storage systems with internal natural convection for canistered spent fuel

    International Nuclear Information System (INIS)

    Yaksh, M.; Wang, C.

    2004-01-01

    In the US, the number of nuclear plants expected to implement on-site dry storage is increasing each year. As reactors burn advanced fuel assemblies to higher burnups, the dry storage systems will be required to accommodate higher heat loads. This is due to the increasing capacity of the systems and the need to store higher burnup fuel with reasonable cooling periods (i.e., five to six years). As the storage systems heat rejection design must be passive, natural convection is an efficient means for rejection of heat from the spent fuel to the surface of the canister boundary. The design presented in this paper is a canistered system that employs conduction, radiation and convection to reject heat from the canister, which is stored in a vertical concrete cask. The canister containing the spent fuel in this design is a right circular stainless steel vessel capable of storing 37 PWR fuel assemblies with a total canister heat load of 40 kW. Accompanying any design effort is the use of a numerical methodology that can accurately predict the peak-clad temperatures of the fuel and the structural components of the system. The main challenge to any analysis employing internal natural convection may be perceived as a practical limitation due to the size of the model. Since canisters are typically cylindrical, a two-dimensional model can be used to represent the canister. The fuel basket structure, which maintains the configuration of the spent fuel, is an array of square tubes, and is non-axisymmetric. Flow up through the fuel region in the basket encounters a complex cross section due to the fuel assembly rod array (up to 17 x 17). The flow region of the heated gas down the outside of the basket in the annulus between the canister shell and the basket assembly (downcomer) is also an irregular shaped area. To confirm that a two-dimensional (2D) modelling methodology is appropriate, a benchmark using results from a thermal test is required. The thermal test focuses on the

  2. Behavior of nuclear waste elements during hydrothermal alteration of glassy rhyolite in an active geothermal system: Yellowstone National Park, Wyoming

    International Nuclear Information System (INIS)

    Sturchio, N.C.; Seitz, M.G.

    1984-01-01

    The behavior of a group of nuclear waste elements (U, Th, Sr, Zr, Sb, Cs, Ba, and Sm) during hydrothermal alteration of glassy rhyolite is investigated through detailed geochemical analyses of whole rocks, glass and mineral separates, and thermal waters. Significant mobility of U, Sr, Sb, Cs, and Ba is found, and the role of sorption processes in their observed behavior is identified. Th, Zr, and Sm are relatively immobile, except on a microscopic scale. 9 references, 2 figures, 2 tables

  3. Statistical Characteristics of Mesoscale Convective Systems over the Middle Reaches area of the Yellow River During 2005-2014

    Science.gov (United States)

    Zhao, Guixiang

    2017-04-01

    Based on the hourly TBB and cloud images of FY-2E, meteorological observation data, and NCEP reanalysis data with 1°×1° spatial resolution from May to October during 2005-2014, the climatic characteristics of mesoscale convective systems (MCS) over the middle reaches area of the Yellow River were analyzed, including mesoscale convective complex (MCC), persistent elongated convective systems (PECS), meso-βscale MCC (MβCCS) and Meso-βscale PECS (MβECS). The results are as follows: (1) MCS tended to occur over the middle and south of Gansu, the middle and south of Shanxi, the middle and north of Shaanxi, and the border of Shanxi, Shaanxi and Inner Mongolia. MCS over the middle reaches area of the Yellow River formed in May to October, and was easy to develop the mature in summer. MCC and MβECS were main MCS causing precipitation in summer. (2) The daily variation of MCS was obvious, and usually formed and matured in the afternoon and the evening to early morning of the next day. Most MCS generated fast and dissipated slowly, and were mainly move to the easterly and southeasterly, but the moving of round shape MCS was less than the elongated shape's. (3) The average TBB for the round shape MCS was lower than the elongated shape MCS. The development of MCC was most vigorous and strong, and it was the strongest in August, while that of MβECS wasn't obviously influenced by the seasonal change. The average eccentricity of the mature MCC and PECS over the middle reaches area of the Yellow River was greater than that in USA, and the former was greater than in the lower reaches area of the Yellow River, while the latter was smaller. (4) The characteristics of rainfall caused by MCS were complex over the middle reaches area of the Yellow River, and there were obvious regional difference. There was wider, stronger and longer precipitation when the multiple MCS merged. The rainfall in the center of cloud area was obviously greater than in other region of cloud area. The

  4. A thermoelectric cap for seafloor hydrothermal vents

    International Nuclear Information System (INIS)

    Xie, Yu; Wu, Shi-jun; Yang, Can-jun

    2016-01-01

    Highlights: • We developed a thermoelectric cap (TC) to harvest hydrothermal energy. • The TC was deployed at a hydrothermal vent site near Kueishantao islet, Taiwan. • The TC monitored the temperature of the hydrothermal fluids during the field test. • The TC could make the thermal energy of hydrothermal fluids a viable power source. - Abstract: Long-term in situ monitoring is crucial to seafloor scientific investigations. One of the challenges of operating sensors in seabed is the lifespan of the sensors. Such sensors are commonly powered by batteries when other alternatives, such as tidal or solar energy, are unavailable. However, the batteries have a limited lifespan and must be recharged or replaced periodically, which is costly and impractical. A thermoelectric cap, which harvests the thermal energy of hydrothermal fluids through a conduction pipe and converts the heat to electrical energy by using thermoelectric generators, was developed to avoid these inconveniences. The thermoelectric cap was combined with a power and temperature measurement system that enables the thermoelectric cap to power a light-emitting diode lamp, an electronic load (60 Ω), and 16 thermocouples continuously. The thermoelectric cap was field tested at a shallow hydrothermal vent site near Kueishantao islet, which is located offshore of northeastern Taiwan. By using the thermal gradient between hydrothermal fluids and seawater, the thermoelectric cap obtained a sustained power of 0.2–0.5 W during the field test. The thermoelectric cap successfully powered the 16 thermocouples and recorded the temperature of the hydrothermal fluids during the entire field test. Our results show that the thermal energy of hydrothermal fluids can be an alternative renewable power source for oceanographic research.

  5. A Sr-isotopic comparison between thermal waters, rocks, and hydrothermal calcites, Long Valley caldera, California

    Science.gov (United States)

    Goff, F.; Wollenberg, H.A.; Brookins, D.C.; Kistler, R.W.

    1991-01-01

    The 87Sr/86Sr values of thermal waters and hydrothermal calcites of the Long Valley caldera geothermal system are more radiogenic than those of young intracaldera volcanic rocks. Five thermal waters display 87Sr/86Sr of 0.7081-0.7078 but show systematically lighter values from west to east in the direction of lateral flow. We believe the decrease in ratio from west to east signifies increased interaction of deeply circulating thermal water with relatively fresh volcanic rocks filling the caldera depression. All types of pre-, syn-, and post-caldera volcanic rocks in the west and central caldera have (87Sr/86Sr)m between about 0.7060 and 0.7072 and values for Sierra Nevada granodiorites adjacent to the caldera are similar. Sierran pre-intrusive metavolcanic and metasedimentary rocks can have considerably higher Sr-isotope ratios (0.7061-0.7246 and 0.7090-0.7250, respectively). Hydrothermally altered volcanic rocks inside the caldera have (87Sr/86Sr)m slightly heavier than their fresh volcanic equivalents and hydrothermal calcites (0.7068-0.7105) occupy a midrange of values between the volcanic/plutonic rocks and the Sierran metamorphic rocks. These data indicate that the Long Valley geothermal reservoir is first equilibrated in a basement complex that contains at least some metasedimentary rocks. Reequilibration of Sr-isotope ratios to lower values occurs in thermal waters as convecting geothermal fluids flow through the isotopically lighter volcanic rocks of the caldera fill. ?? 1991.

  6. Nonlinear convective flows in a two-layer system under the action of spatial temperature modulation of heat release/consumption at the interface

    Science.gov (United States)

    Simanovskii, Ilya B.; Viviani, Antonio; Dubois, Frank

    2018-06-01

    An influence of a spatial temperature modulation of the interfacial heat release/consumption on nonlinear convective flows in the 47v2 silicone oil - water system, is studied. Rigid heat-insulated lateral walls, corresponding to the case of closed cavities, have been considered. Transitions between the flows with different spatial structures, have been investigated. It is shown that the spatial modulation can change the sequence of bifurcations and lead to the appearance of specific steady and oscillatory flows in the system.

  7. Constant system for by-channel thermal-hydraulic calculation of fuel assembly operational conditions in reactors with natural and mixed convection

    International Nuclear Information System (INIS)

    Bogatyrev, I.L.; Bogoslovskaya, G.P.; Zhukov, A.V.; Sorokin, A.P.; Titov, P.A.

    1992-01-01

    System of constants for mass, impulse and energy conservation equations (drag, mixing, heat transfer coefficients, azimuthal unquality of temperature) is reported in region with small Re number for wide range of geometrical assembly parameters. This system can be used in subchannel calculations of assemblies with natural and mixed convection under conditions with loss of flow accident. The formulae are compared with experimental data. 30 refs.; 12 figs.; 1 tab

  8. Exploring the structural controls on helium, nitrogen and carbon isotope signatures in hydrothermal fluids along an intra-arc fault system

    Science.gov (United States)

    Tardani, Daniele; Reich, Martin; Roulleau, Emilie; Takahata, Naoto; Sano, Yuji; Pérez-Flores, Pamela; Sánchez-Alfaro, Pablo; Cembrano, José; Arancibia, Gloria

    2016-07-01

    There is a general agreement that fault-fracture meshes exert a primary control on fluid flow in both volcanic/magmatic and geothermal/hydrothermal systems. For example, in geothermal systems and epithermal gold deposits, optimally oriented faults and fractures play a key role in promoting fluid flow through high vertical permeability pathways. In the Southern Volcanic Zone (SVZ) of the Chilean Andes, both volcanism and hydrothermal activity are strongly controlled by the Liquiñe-Ofqui Fault System (LOFS), an intra-arc, strike-slip fault, and by the Arc-oblique Long-lived Basement Fault System (ALFS), a set of transpressive NW-striking faults. However, the role that principal and subsidiary fault systems exert on magma degassing, hydrothermal fluid flow and fluid compositions remains poorly constrained. In this study we report new helium, carbon and nitrogen isotope data (3He/4He, δ13C-CO2 and δ15N) of a suite of fumarole and hot spring gas samples from 23 volcanic/geothermal localities that are spatially associated with either the LOFS or the ALFS in the central part of the SVZ. The dataset is characterized by a wide range of 3He/4He ratios (3.39 Ra to 7.53 Ra, where Ra = (3He/4He)air), δ13C-CO2 values (-7.44‰ to -49.41‰) and δ15N values (0.02‰ to 4.93‰). The regional variations in 3He/4He, δ13C-CO2 and δ15N values are remarkably consistent with those reported for 87Sr/86Sr in lavas along the studied segment, which are strongly controlled by the regional spatial distribution of faults. Two fumaroles gas samples associated with the northern ;horsetail; transtensional termination of the LOFS are the only datapoints showing uncontaminated MORB-like 3He/4He signatures. In contrast, the dominant mechanism controlling helium isotope ratios of hydrothermal systems towards the south appears to be the mixing between mantle-derived helium and a radiogenic component derived from, e.g., magmatic assimilation of 4He-rich country rocks or contamination during the

  9. Salt shell fallout during the ash eruption at the Nakadake crater, Aso volcano, Japan: evidence of an underground hydrothermal system surrounding the erupting vent

    Science.gov (United States)

    Shinohara, Hiroshi; Geshi, Nobuo; Yokoo, Akihiko; Ohkura, Takahiro; Terada, Akihiko

    2018-03-01

    A hot and acid crater lake is located in the Nakadake crater, Aso volcano, Japan. The volume of water in the lake decreases with increasing activity, drying out prior to the magmatic eruptions. Salt-rich materials of various shapes were observed, falling from the volcanic plume during the active periods. In May 2011, salt flakes fell from the gas plume emitted from an intense fumarole when the acid crater lake was almost dry. The chemical composition of these salt flakes was similar to those of the salts formed by the drying of the crater lake waters, suggesting that they originated from the crater lake water. The salt flakes are likely formed by the drying up of the crater lake water droplets sprayed into the plume by the fumarolic gas jet. In late 2014, the crater lake dried completely, followed by the magmatic eruptions with continuous ash eruptions and intermittent Strombolian explosions. Spherical hollow salt shells were observed on several occasions during and shortly after the weak ash eruptions. The chemical composition of the salt shells was similar to the salts formed by the drying of the crater lake water. The hollow structure of the shells suggests that they were formed by the heating of hydrothermal solution droplets suspended by a mixed stream of gas and ash in the plume. The salt shells suggest the existence of a hydrothermal system beneath the crater floor, even during the course of magmatic eruptions. Instability of the magmatic-hydrothermal interface can cause phreatomagmatic explosions, which often occur at the end of the eruptive phase of this volcano.

  10. Study of plasma convection and wall interactions in magnetic-confinement systems. Progress report, October 1, 1980-September 30, 1981

    International Nuclear Information System (INIS)

    York, T.M.; Klevans, E.H.

    1981-01-01

    Experimental and analytical studies of plasma interactions with magnetic fields and end walls have been carried out. The final effort for studying flow on open-ended theta pinches has resulted in: (1) new understanding of collisional flow processes; and (2) has presented unique measurements of density and temperature near the end wall. An orignal effort to use Nd-glass lasers for Thomson scattering diagnostics is reported. Laser system conversion and efficiencies of frequency doubling are reported. The development of a compact toroid discharged is reported; this will be used as a plasma source to study transport, convection and wass interactions at plasma conditions appropriate for large scale fusion experiments. Computer codes predict compact toroid plasma scaling and magnetic field distribution resulting from guiding coils added at the ends of the theta pinch coil. The development of a multi-pass Fabry-Perot interferometer using visible light from a He-Ne laser is reported here. Theoretical study has been completed on an extension of a collisionless plasma flow model to include collision effects. Initial studies directed to analysis of plasma wall interactions are reported

  11. The implications of dust ice nuclei effect on cloud top temperature in a complex mesoscale convective system.

    Science.gov (United States)

    Li, Rui; Dong, Xue; Guo, Jingchao; Fu, Yunfei; Zhao, Chun; Wang, Yu; Min, Qilong

    2017-10-23

    Mineral dust is the most important natural source of atmospheric ice nuclei (IN) which may significantly mediate the properties of ice cloud through heterogeneous nucleation and lead to crucial impacts on hydrological and energy cycle. The potential dust IN effect on cloud top temperature (CTT) in a well-developed mesoscale convective system (MCS) was studied using both satellite observations and cloud resolving model (CRM) simulations. We combined satellite observations from passive spectrometer, active cloud radar, lidar, and wind field simulations from CRM to identify the place where ice cloud mixed with dust particles. For given ice water path, the CTT of dust-mixed cloud is warmer than that in relatively pristine cloud. The probability distribution function (PDF) of CTT for dust-mixed clouds shifted to the warmer end and showed two peaks at about -45 °C and -25 °C. The PDF for relatively pristine cloud only show one peak at -55 °C. Cloud simulations with different microphysical schemes agreed well with each other and showed better agreement with satellite observations in pristine clouds, but they showed large discrepancies in dust-mixed clouds. Some microphysical schemes failed to predict the warm peak of CTT related to heterogeneous ice formation.

  12. Investigation of Mineral Alteration in Andesite and Dacite from Three Different Volcano Hydrothermal Systems on Dominica, Lesser Antilles

    Science.gov (United States)

    Smith, C. I. V.; Frey, H. M.; Joseph, E. P.; Manon, M. R. F.

    2017-12-01

    The thermal discharges of Dominica are classified as steam-heated acidic-sulphate waters, produced by the mixing of shallow ground waters heated by sulphur bearing gases coming from magmatic sources. This study investigates the mineral alteration associated with three hydrothermal areas in Dominica that exhibit different temperature, pH, water composition and surface water abundance. Hydrothermal features (fumaroles, pools, springs) from Sulphur Springs ranged in temperature from 41 - 97 °C and pH from 1-3 in a predominantly gaseous environment, whereas the Valley of Desolation (69-98 °C and pH 1- 4) and the Cold Soufriere (18-32 °C and pH 1-4) have significant inputs of surface water. At each location, the host andesite-dacite rock was enveloped by a thin rind (up 2 cm) of precipitates, but the degree of alteration and rind thickness/composition varied with location. Cobbles from Sulphur Springs (SS) are grayish white in color with a thin outer rind (3-13 mm), and seemingly unaltered cores. Valley of Desolation (VoD) samples have a variety of patterns of alteration, with some clasts a uniform white-orange color, whereas others have variable thicknesses of an altered rind (1-20 mm), with relatively unaltered cores. Multiple hydrothermal minerals precipitated in the outer rinds display distinctive colors, suggestive of sulphides (dark gray), sulphates (orange and yellow), and iron oxides(?) (pink and purple). Cold Soufriere (CS) samples appear to be the most altered, often crumbling at touch. Others had rinds (2-10 mm) and pinkish gray cores that suggest more alteration compared to VoD and SS samples. Preliminary mineral identification of rind compositions was determined by XRD. Scans indicate the presence of silica polymorphs cristobalite and tridymite, as well as pyrite and sulphur. Elemental maps created using a SEM to identify any gradation caused by the elemental leaching and/or precipitation show that the boundaries between the weathering rind and the host

  13. Planning of the power hydrothermal system operation - alternatives for the modelling and uncertainties treatment; Planejamento da operacao de sistemas hidrotermicos de potencia - alternativas de modelagem e o tratamento das incertezas

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Andre Flavio Soares; Bajay, Sergio Valdir [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica]|[Universidade Estadual de Campinas, SP (Brazil). Nucleo Interdisciplinar de Planejamento Energetico (NIPE)]. E-mails: apereira@fem.unicamp.br; bajay@fem.unicamp.br; Barbosa, Paulo Sergio Franco [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Civil]|[Universidade Estadual de Campinas, SP (Brazil). Nucleo Interdisciplinar de Planejamento Energetico (NIPE)]. E-mail: franco@fec.unicamp.br

    2006-07-01

    The complexity of the operation scheduling of hydrothermal power systems lies, among other factors, in the interconnection between the operation decision in a certain stage and the future consequences of such decision. The operation of a hydrothermal power system comprises from the supervision and real time control of the generation and transport of electricity, to aspects as the modelling of the uncertainties concerning the future stream flows and the optimised management of the hydro power plant reservoirs. This work addresses a general formulation of the operation scheduling problem of hydrothermal power systems; a brief presentation of the various optimization techniques which can be used in its solution; and a discussion about the main alternatives that has been adopted to model the problem and to deal with its main uncertainties. (author)

  14. Calcite veining and feeding conduits in a hydrothermal system: Insights from a natural section across the Pleistocene Gölemezli travertine depositional system (western Anatolia, Turkey)

    Science.gov (United States)

    Capezzuoli, Enrico; Ruggieri, Giovanni; Rimondi, Valentina; Brogi, Andrea; Liotta, Domenico; Alçiçek, Mehmet Cihat; Alçiçek, Hülya; Bülbül, Ali; Gandin, Anna; Meccheri, Marco; Shen, Chuan-Chou; Baykara, Mehmet Oruç

    2018-02-01

    Linking the architecture of structural conduits with the hydrothermal fluids migrating from the reservoir up to the surface is a key-factor in geothermal research. A contribution to this achievement derives from the study of spring-related travertine deposits, but although travertine depositional systems occur widely, their feeding conduits are only rarely exposed. The integrated study carried out in the geothermal Gölemezli area, nearby the well-known Pamukkale area (Denizli Basin, western Anatolia, Turkey), focused on onyx-like calcite veins (banded travertine) and bedded travertine well exposed in a natural cross-section allowing the reconstruction of the shallower part of a geothermal system. The onyx-like veins represent the thickest vein network (> 150 m) so far known. New field mapping and structural/kinematic analyses allowed to document a partially dismantled travertine complex (bedded travertine) formed by proximal fissure ridges and distal terraced/pools depositional systems. The banded calcite veins, WNW-trending and up to 12 m thick, developed within a > 200 m thick damaged rock volume produced by parallel fault zones. Th/U dating indicates a long lasting (middle-late Pleistocene) fluids circulation in a palaeo-geothermal system that, due to its location and chemical characteristics, can be considered the analogue of the nearby, still active, Pamukkale system. The isotopic characteristics of the calcite veins together with data from fluid inclusions analyses, allow the reconstruction of some properties (i.e. temperature, salinity and isotopic composition) and processes (i.e. temperature variation and intensity of degassing) that characterized the parent fluids and the relation between degassing intensity and specific microfabric of calcite crystals (elongated/microsparite-micrite bands), controlled by changes/fluctuations of the physico-chemical fluid characteristics.

  15. Geochemistry of sericite and chlorite in well 14-2 Roosevelt Hot Springs geothermal system and in mineralized hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Ballantyne, J.M.

    1980-06-01

    Chemical compositions of chlorite and sericite from one production well in the Roosevelt geothermal system have been determined by electron probe methods and compared with compositions of chlorite and sericite from porphyry copper deposits. Modern system sericite and chlorite occur over a depth interval of 2 km and a temperature interval of 250/sup 0/C.

  16. Thermal Comfort in Simulated Office Environment with Four Convective and Radiant Cooling Systems

    DEFF Research Database (Denmark)

    Bolashikov, Zhecho Dimitrov; Mustakallio, Panu; Kolencíková, Sona

    2013-01-01

    with overhead mixing ventilation (MVRC). Whole body thermal sensation (TS) and whole body TS acceptability under the four systems in a simulated office room for one hour exposure were collected. The simulated two-man office (4.12 x 4.20 x 2.89 m, L x W x H) was kept at 26 oC room air temperature. Moderate heat...... to “neutral” compared to male, whose votes were closer to the “slightly warm” thermal sensation. The whole body TS acceptability was rated close to ''clearly acceptable'' (EN 15251-2007) and was independent of subject's gender for all tested systems....

  17. Thermal Conditions in a Simulated Office Environment with Convective and Radiant Cooling Systems

    DEFF Research Database (Denmark)

    Mustakallio, Panu; Bolashikov, Zhecho Dimitrov; Kostov, Kalin

    2013-01-01

    velocity and turbulent intensity were measured and draft rate levels calculated in the room. Manikin-based equivalent temperature (MBET) was determined by two thermal manikins to identify the impact of the local thermal conditions generated by the studied systems on occupants’ thermal comfort. The results......The thermal conditions in a two person office room were measured with four air conditioning systems: chilled beam (CB), chilled beam with radiant panel (CBR), chilled ceiling with ceiling installed mixing ventilation (CCMV) and four desk partition mounted local radiant cooling panels with mixing...

  18. A Climatology of Derecho-Producing Mesoscale Convective Systems in the Central and Eastern United States, 1986-95. Part I: Temporal and Spatial Distribution.

    Science.gov (United States)

    Bentley, Mace L.; Mote, Thomas L.

    1998-11-01

    In 1888, Iowa weather researcher Gustavus Hinrichs gave widespread convectively induced windstorms the name "derecho". Refinements to this definition have evolved after numerous investigations of these systems; however, to date, a derecho climatology has not been conducted.This investigation examines spatial and temporal aspects of derechos and their associated mesoscale convective systems that occurred from 1986 to 1995. The spatial distribution of derechos revealed four activity corridors during the summer, five during the spring, and two during the cool season. Evidence suggests that the primary warm season derecho corridor is located in the southern Great Plains. During the cool season, derecho activity was found to occur in the southeast states and along the Atlantic seaboard. Temporally, derechos are primarily late evening or overnight events during the warm season and are more evenly distributed throughout the day during the cool season.

  19. Thermal environment in a simulated double office room with convective and radiant cooling systems

    DEFF Research Database (Denmark)

    Mustakallio, Panu; Bolashikov, Zhecho Dimitrov; Rezgals, Lauris

    2017-01-01

    anddraught rate was calculated. Manikin-based equivalent temperature (MBET) was determined by using two thermal manikins. CCMV provided slightly more uniform thermal environment and the least sensitive to different workstation layouts than the other systems. CB provided a bit higher draught rate levels than...

  20. A stochastic approach to long term operation planning of hydrothermal systems; Uma abordagem estocastica para o planejamento a longo prazo da operacao de sistemas hidrotermicos

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marinho G. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Ciencias Matematicas; Soares, Secundino; Cruz Junior, Gelson da; Vinhal, Cassio D.N. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Eletrica

    1996-01-01

    This paper is concerned with long term operation of hydro-thermal power systems. The problem is approached by a deterministic optimization technique coupled to an inflow forecasting model in open-loop feedback framework in monthly basis. The paper aims to compare the solution obtained by this approach and Stochastic Dynamic Programming (SDP), which has been accepted for over than two decades as the better solution to deal with inflow uncertainty in long term planning. The comparison was carried out in systems with a single plant, simulating the operation throughout a period of five years under the historical inflow conditions and evaluating the cost of the complementary thermal generation. Results show that the proposed approach can handle uncertainty as effectively as SDP. Furthermore, it does not require modeling simplification, such as composite reservoirs, to deal with multi hydro plant systems. 10 refs., 1 tab.

  1. Hydrothermal liquefaction of biomass

    DEFF Research Database (Denmark)

    Toor, Saqib; Rosendahl, Lasse; Rudolf, Andreas

    2011-01-01

    This article reviews the hydrothermal liquefaction of biomass with the aim of describing the current status of the technology. Hydrothermal liquefaction is a medium-temperature, high-pressure thermochemical process, which produces a liquid product, often called bio-oil or bi-crude. During...... the hydrothermal liquefaction process, the macromolecules of the biomass are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive and can recombine into larger ones. During this process, a substantial part of the oxygen in the biomass is removed...... by dehydration or decarboxylation. The chemical properties of bio-oil are highly dependent of the biomass substrate composition. Biomass constitutes of various components such as protein; carbohydrates, lignin and fat, and each of them produce distinct spectra of compounds during hydrothermal liquefaction...

  2. Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems

    Science.gov (United States)

    Nordstrom, D. Kirk; Guo, Qinghai; McCleskey, R. Blaine

    2014-01-01

    Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1–2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.

  3. Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems

    Science.gov (United States)

    Guo, Qinghai; Kirk Nordstrom, D.; Blaine McCleskey, R.

    2014-11-01

    Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1-2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.

  4. An Overview of Thermal Measurements (IR) at the Summit of Piton de la Fournaise Active Volcano and Inferences on the Structure and Dynamics of its Hydrothermal System

    Science.gov (United States)

    Fontaine, F.; Peltier, A.; Kowalski, P.; Di Muro, A.; Villeneuve, N.; Ferrazzini, V.; Staudacher, T.

    2017-12-01

    Piton de la Fournaise, located on La Réunion Island in the South East Indian Ocean, is one of the most active basaltic volcanoes (hotspot) of the world with a mean eruption frequency 100×106 m3) on the island, led to the formation of a 400-m-deep, 1000-m-large, funnel-shaped summit caldera. Since then, the floor and inner flanks of this summit depression hosting hot grounds and active fumaroles, are monitored using an infra-red camera device permanently installed on the caldera rim.This thermal dataset constitutes the first opportunity to understand the structure and dynamics of the hydrothermal system and its ability to relay deep-seated heat and mass perturbations. We present in this communication an overview of this thermal datasets focusing on ground/fumaroles temperature evolution during volcanic crisis and rest periods and analyzing correlations with the other permanently acquired data such as the temporal evolution of gas geochemistry (CO2, SO2, H2S), ground deformation and micro-seismic activity. We finally propose a conceptual model of fluid flow architecture within the edifice which paves the way for future quantitative models of hydrothermal heat and mass transfers.

  5. Fault-Related Controls on Upward Hydrothermal Flow: An Integrated Geological Study of the Têt Fault System, Eastern Pyrénées (France

    Directory of Open Access Journals (Sweden)

    Audrey Taillefer

    2017-01-01

    Full Text Available The way faults control upward fluid flow in nonmagmatic hydrothermal systems in extensional context is still unclear. In the Eastern Pyrénées, an alignment of twenty-nine hot springs (29°C to 73°C, along the normal Têt fault, offers the opportunity to study this process. Using an integrated multiscale geological approach including mapping, remote sensing, and macro- and microscopic analyses of fault zones, we show that emergence is always located in crystalline rocks at gneiss-metasediments contacts, mostly in the Têt fault footwall. The hot springs distribution is related to high topographic reliefs, which are associated with fault throw and segmentation. In more detail, emergence localizes either (1 in brittle fault damage zones at the intersection between the Têt fault and subsidiary faults or (2 in ductile faults where dissolution cavities are observed along foliations, allowing juxtaposition of metasediments. Using these observations and 2D simple numerical simulation, we propose a hydrogeological model of upward hydrothermal flow. Meteoric fluids, infiltrated at high elevation in the fault footwall relief, get warmer at depth because of the geothermal gradient. Topography-related hydraulic gradient and buoyancy forces cause hot fluid rise along permeability anisotropies associated with lithological juxtapositions, fracture, and fault zone compositions.

  6. Relationships of dispersive mass transport and stochastic convective flow through hydrologic systems

    International Nuclear Information System (INIS)

    Simmons, C.S.

    1981-01-01

    Uncertainty in water flow velocity appears to be a major factor in determining the magnitude of contaminant dispersion expected in a ground water system. This report discusses some concepts and mathematical methods relating dispersive contaminant transport to stochastic aspects of ground water flow. The theory developed should not be construed as absolutely rigorous mathematics, but is presented with the intention of clarifying the physical concepts

  7. Convective heat exposure from large fires to the final filters of ventilation systems

    International Nuclear Information System (INIS)

    Alvares, N.J.

    1979-01-01

    The Fire Science Group of the Hazards Control Department, Lawrence Livermore Laboratory has been asked to design a probable fire scenario for a fuel-pellet fabrication facility. This model was used to estimate the potential for thermal damage to the final HEPA filters. These filters would not experience direct fire exposure because they are the last component of the ventilation system before the exhaust air pumps. However, they would be exposed to hot air and fire gases that are drawn into the ventilation system. Because fire is one of the few occurrences that can defeat the containment integrity of facilities where radioactive materials are stored and processed, the fire scenarios must be defined to ensure that containment systems are adequate to meet the threat of such events. Fire-growth calculations are based on the measured fuel load of materials within the fabrication enclosure and on semi-empirical fire-spread models. It is assumed that the fire never becomes ventilation controlled. The temperature rise of ceiling gases and heat transfer from ventilation ducting are calculated using accepted empirical relationships, and the analysis shows that even under the most severe exposure conditions, heat transfer from the duct reduces the fire gas temperatures to levels that would not hamper filter function

  8. National Convective Weather Forecast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NCWF is an automatically generated depiction of: (1) current convection and (2) extrapolated signficant current convection. It is a supplement to, but does NOT...

  9. The Next-Generation Goddard Convective-Stratiform Heating Algorithm: Addressing Higher Latitude, Cold Season, and Synoptic Systems

    Science.gov (United States)

    Wu, D.; Tao, W. K.; Lang, S. E.

    2016-12-01

    The Goddard Convective-Stratiform Heating (or CSH) algorithm is used to retrieve estimates of cloud heating over the global Tropics using TRMM rainfall data and a set of look-up-tables (LUTs) derived from a series of multi-week cloud-resolving model (CRM) simulations using the Goddard Cumulus Ensemble model (or GCE). These simulations link satellite observables (i.e., surface rainfall and stratiform fraction) with cloud heating profiles, which are not directly observable. The current CSH LUTs are differentiated with respect to surface rainfall characteristics, which is effective for tropical and continental summertime environments. However, with the launch of GPM in 2014, the range over which such algorithms can be applied has been extended from the Tropics and mid-latitudes to higher latitudes, including cold season and synoptic weather systems. Accordingly, the CSH algorithm and LUTs need to be updated for higher latitude events. In this study, NU-WRF was employed at 1 km to simulate winter systems in the US. A, new methodology has been adopted to construct LUTs utilizing satellite-observable 3D intensity fields, such as radar reflectivity. The new methodology/LUTs can be then applied to simulated radar fields to derive cloud heating for comparison against the model simulated heating. The model heating is treated as the `truth' as it is self-consistent with the simulated radar fields. This `consistency check' approach is a common well-established first step in algorithm development (e.g., the earlier CSH). The LUTs will be improved by iterating the consistency checks to quantitatively evaluate the similarities between the retrieved and simulated heating. The evaluations will be performed for different weather events, including northeast winter storms and atmospheric rivers.

  10. Bidispersive-inclined convection

    Science.gov (United States)

    Mulone, Giuseppe; Straughan, Brian

    2016-01-01

    A model is presented for thermal convection in an inclined layer of porous material when the medium has a bidispersive structure. Thus, there are the usual macropores which are full of a fluid, but there are also a system of micropores full of the same fluid. The model we employ is a modification of the one proposed by Nield & Kuznetsov (2006 Int. J. Heat Mass Transf. 49, 3068–3074. (doi:10.1016/j.ijheatmasstransfer.2006.02.008)), although we consider a single temperature field only. PMID:27616934

  11. NCAR's Experimental Real-time Convection-allowing Ensemble Prediction System

    Science.gov (United States)

    Schwartz, C. S.; Romine, G. S.; Sobash, R.; Fossell, K.

    2016-12-01

    Since April 2015, the National Center for Atmospheric Research's (NCAR's) Mesoscale and Microscale Meteorology (MMM) Laboratory, in collaboration with NCAR's Computational Information Systems Laboratory (CISL), has been producing daily, real-time, 10-member, 48-hr ensemble forecasts with 3-km horizontal grid spacing over the conterminous United States (http://ensemble.ucar.edu). These computationally-intensive, next-generation forecasts are produced on the Yellowstone supercomputer, have been embraced by both amateur and professional weather forecasters, are widely used by NCAR and university researchers, and receive considerable attention on social media. Initial conditions are supplied by NCAR's Data Assimilation Research Testbed (DART) software and the forecast model is NCAR's Weather Research and Forecasting (WRF) model; both WRF and DART are community tools. This presentation will focus on cutting-edge research results leveraging the ensemble dataset, including winter weather predictability, severe weather forecasting, and power outage modeling. Additionally, the unique design of the real-time analysis and forecast system and computational challenges and solutions will be described.

  12. Instabilities in parallel channel of forced-convection boiling upflow system, 5

    International Nuclear Information System (INIS)

    Aritomi, Masanori; Aoki, Shigebumi; Inoue, Akira

    1983-01-01

    The density wave instability in a parallel boiling channel system heated electrically has been studied experimentally and analytically by the authors. In our country, the steam generator for LMFBR has been investigated with Power Reactor and Nuclear Fuel Development Corp. as the central figure for its development, and many results of this instability were reported. Their results were different from our ones as regard to the governing factor of the period of flow oscillation in the unstable region and to the effect of the slip ratio on the stability in analysis. A new linear analytical model is proposed in this paper and the analytical results are compared with ones of two-phase analyses based on the same linear method as this model. Subsequently, the effect of the slip ratio on the stability is studied analytically by this model. The parallel boiling channel system is studied experimentally and analytically, using Freon-113 as test fluid heated by hot water as simulation of the SG for LMFBR. The governing factor of the period of flow oscillation is made clear. (author)

  13. Mantle Convection on Modern Supercomputers

    Science.gov (United States)

    Weismüller, J.; Gmeiner, B.; Huber, M.; John, L.; Mohr, M.; Rüde, U.; Wohlmuth, B.; Bunge, H. P.

    2015-12-01

    Mantle convection is the cause for plate tectonics, the formation of mountains and oceans, and the main driving mechanism behind earthquakes. The convection process is modeled by a system of partial differential equations describing the conservation of mass, momentum and energy. Characteristic to mantle flow is the vast disparity of length scales from global to microscopic, turning mantle convection simulations into a challenging application for high-performance computing. As system size and technical complexity of the simulations continue to increase, design and implementation of simulation models for next generation large-scale architectures is handled successfully only in an interdisciplinary context. A new priority program - named SPPEXA - by the German Research Foundation (DFG) addresses this issue, and brings together computer scientists, mathematicians and application scientists around grand challenges in HPC. Here we report from the TERRA-NEO project, which is part of the high visibility SPPEXA program, and a joint effort of four research groups. TERRA-NEO develops algorithms for future HPC infrastructures, focusing on high computational efficiency and resilience in next generation mantle convection models. We present software that can resolve the Earth's mantle with up to 1012 grid points and scales efficiently to massively parallel hardware with more than 50,000 processors. We use our simulations to explore the dynamic regime of mantle convection and assess the impact of small scale processes on global mantle flow.

  14. An alternative rule for determining demand and energy supply based in marginal cost optimization from interconnected hydrothermal systems, focalizing the individualized plants, applied to the interconnected system from South and Southeast regions of Brazil

    International Nuclear Information System (INIS)

    Souza Bond, P. de; Soares Filho, S.

    1989-01-01

    A methodology for determining optimal strategies of energy supply in the interconnected system from South and Southeast regions of Brazil is presented. The problem was modelled, having as principle the minimization of operation pluri annual cost. The dynamic restrictions of energy and peak flow, the dynamic configuration of hydrothermal park and the hydraulic operation restrictions are also considered. (C.G.C.). 7 refs, 3 tabs

  15. Modeling of convective drying kinetics of Pistachio kernels in a fixed bed drying system

    Directory of Open Access Journals (Sweden)

    Balbay Asım

    2013-01-01

    Full Text Available Drying kinetics of Pistachio kernels (PKs with initial moisture content of 32.4% (w.b was investigated as a function of drying conditions in a fixed bed drying system. The drying experiments were carried out at different temperatures of drying air (40, 60 and 80°C and air velocities (0.05, 0.075 and 0.1 m/s. Several experiments were performed in terms of mass of PKs (15g and 30g using a constant air velocity of 0.075 m/s. The fit quality of models was evaluated using the determination coefficient (R2, sum square error (SSE and root mean square error (RMSE. Among the selected models, the Midilli et al model was found to be the best models for describing the drying behavior of PKs. The activation energies were calculated as 29.2 kJ/mol and effective diffusivity values were calculated between 1.38 and 4.94x10-10 m2/s depending on air temperatures.

  16. Analysis of corrosion product transport in PWR primary system under non-convective condition

    International Nuclear Information System (INIS)

    Han, Byoung Sub

    1992-02-01

    Product TRANsport), which can predict the corrosion product and radioactivity transport within the primary coolant system, and also can be utilized for the computer simulation with actual plant data of currently operating Korean nuclear power plants to predict the transport of the radionuclides. In this study, the following problems will be updated, improved and compared with the already existing codes: 1) development and analysis of recent mechanistic modelling of corrosion product deposition, 2) application and modification due to the temperature kinetic effect, 3) separation of the effect of Fe, Co, Ni and Mn solubility rather than Fe solubility alone, and 4) consideration of Ni activation and recoil process. By applying the above updated and improved mechanisms, the corrosion product behavior in PWR of currently operating Korean unclear power plants has been simulated. In addition, the evaluation of particulate transport, independent solubility data of major radionuclides and acute nodalization were included and extended. Then, with the developed computer code, we have evaluated and analyzed the activity and corrosion product build-up controlled by many parameters such as pH, composition of metal, and auxiliary system performance

  17. Hydrothermal Processes in the Archean - New Insights from Imaging Spectroscopy

    NARCIS (Netherlands)

    Ruitenbeek, F.J.A. van

    2007-01-01

    The aim of this research was to gain new insights in fossil hydrothermal systems using airborne imaging spectroscopy. Fossil submarine hydrothermal systems in Archean greenstone belts and other geologic terranes are important because of their relationship with volcanic massive sulfide (VMS) mineral

  18. Physical, chemical and mineralogical evolution of the Tolhuaca geothermal system, southern Andes, Chile: Insights into the interplay between hydrothermal alteration and brittle deformation

    Science.gov (United States)

    Sanchez-Alfaro, Pablo; Reich, Martin; Arancibia, Gloria; Pérez-Flores, Pamela; Cembrano, José; Driesner, Thomas; Lizama, Martin; Rowland, Julie; Morata, Diego; Heinrich, Christoph A.; Tardani, Daniele; Campos, Eduardo

    2016-09-01

    In this study, we unravel the physical, chemical and mineralogical evolution of the active Tolhuaca geothermal system in the Andes of southern Chile. We used temperature measurements in the deep wells and geochemical analyses of borehole fluid samples to constrain present-day fluid conditions. In addition, we reconstructed the paleo-fluid temperatures and chemistry from microthermometry and LA-ICP-MS analysis of fluid inclusions taken from well-constrained parageneses in vein samples retrieved from a 1000 m borehole core. Based on core logging, mineralogical observations and fluid inclusions data we identify four stages (S1-S4) of progressive hydrothermal alteration. An early heating event (S1) was followed by the formation of a clay-rich cap in the upper zone (propylitic alteration assemblage at greater depth (S2). Boiling, flashing and brecciation occurred later (S3), followed by a final phase of fluid mixing and boiling (S4). The evolution of hydrothermal alteration at Tolhuaca has produced a mineralogical, hydrological and structural vertical segmentation of the system through the development of a low-permeability, low-cohesion clay-rich cap at shallow depth. The quantitative chemical analyses of fluid inclusions and borehole fluids reveal a significant change in chemical conditions during the evolution of Tolhuaca. Whereas borehole (present-day) fluids are rich in Au, B and As, but Cu-poor (B/Na 100.5, As/Na 10- 1.1, Cu/Na 10- 4.2), the paleofluids trapped in fluid inclusions are Cu-rich but poor in B and As (B/Na 10- 1, As/Na 10- 2.5, Cu/Na 10- 2.5 in average). We interpret the fluctuations in fluid chemistry at Tolhuaca as the result of transient supply of metal-rich, magmatically derived fluids where As, Au and Cu are geochemically decoupled. Since these fluctuating physical and chemical conditions at the reservoir produced a mineralogical vertical segmentation of the system that affects the mechanical and hydrological properties of host rock, we explored

  19. On the role of convective systems over the northwest Pacific and monsoon activity over the Indian subcontinent

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Babu, A; Reason, C.

    been examined in relation to breaks in monsoon conditions over the Indian sub-continent during contrasting monsoon years. A see-saw nature of convection between the NWP and north Indian Ocean was found during the years with excess monsoon rainfall...

  20. Experimental Investigations of Boron, Lithium, and Halogens During High-Temperature Water-Rock Interaction: Insights into the Yellowstone Hydrothermal System

    Science.gov (United States)

    Cullen, J. T.; Hurwitz, S.; Thordsen, J. J.; Barnes, J.

    2017-12-01

    B, Li, and halogens (Cl, F, Br) are used extensively in studies of thermal waters to infer fluid equilibrium conditions with the host reservoir lithology, and quantify the possible fraction of a magmatic component in thermal waters. Apart from fluorine, the limited number of minerals that incorporate these elements support the notion that they preferentially partition into an aqueous fluid during high temperature water-rock interaction. Although limited experimental work is largely consistent with these observations, a rigorous experimental investigation is required to quantify the mobility of these elements under conditions emulating a silicic hydrothermal system. Here we present the results from water-rhyolite interaction batch experiments conducted over a range of temperatures between 150 °C and 350 °C and 250 bar. Powdered obsidian from Yellowstone was reacted with MiliQ water and sampled intermittently throughout the duration of the 90 day experiment. The experimental data show that at temperatures ≤ 200 °C, B, Cl, Br, and Li are not readily leached from the rhyolite, whereas aqueous F- concentration increases by a factor of 3.5 when the temperature was increased from 150 °C to 200 °C. Between 200 °C and 250 °C, B concentration increased by more than an order of magnitude and Cl- concentration increased by a factor of 5. F- concentration increased by a factor of 3. Between 250 °C and 300 °C the opposite trend was observed, in which F- concentration decreased by 60%, Br- concentration increased by a factor of 5, and Cl- and B concentrations increased by more than an order of magnitude. The progressive decrease of aqueous F- at T ≥ 300 °C is likely controlled by precipitation into a fluorine bearing secondary mineral(s). Our experimental results demonstrate that leaching of B, Li, Cl, F, and Br from rhyolite is highly temperature-dependent between 150 °C and 350 °C. These results can provide context to infer the sources of solutes discharged at

  1. Seismic Characterization of Hypogenic Karst Systems Associated with Deep Hydrothermal Fluids in the Middle-Lower Ordovician Yingshan Formation of the Shunnan Area, Tarim Basin, NW China

    Directory of Open Access Journals (Sweden)

    Hongtao Zhu

    2017-01-01

    Full Text Available Two fundamental forms of hypogenic karst systems (lateral stratiform hypogenic and cross-formational fault-vein hypogenic karst system are distinguished mainly by differential effects of preexisting faults. In seismic cross sections, hypogenic karst systems are expressed as complex string-beads-like seismic reflections associated with faults. In this study, a new seismic characterization workflow was developed including seismic amplitude thresholding, fault interpretation, pickup, and merge display to enhance the description of the spatial distribution and coupling of hypogenic karst system and faults. The results suggest that the lateral stratiform hypogenic karst systems are predominantly developed at the top of the secondary faults, presenting an overall of “layered distribution and finger-like interaction” features. The cross-formational fault-vein hypogenic karst systems are developed around faults and characterized by dendritic distribution. Furthermore, we infer that the development pattern of hypogenic karst systems has been produced by the interplay of the faults, preexisting epigenic karst systems, and lateral carrier-beds, which together combine the complex hydrothermal migration pathways of fluids with the characteristics of vertical and horizontal combined pathways. In addition, some possible controlling factors (e.g., sequence stratigraphic boundaries, paleogeomorphology, and sedimentary facies that can influence the development of these hypogenic karst systems have been discussed in detail.

  2. Impact of Lake Okeechobee Sea Surface Temperatures on Numerical Predictions of Summertime Convective Systems over South Florida

    Science.gov (United States)

    Case, Jonathan L.; Splitt, Michael E.; Fuell, Kevin K.; Santos, Pablo; Lazarus, Steven M.; Jedlovec, Gary J.

    2009-01-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center, the Florida Institute of Technology, and the NOAA/NWS Weather Forecast Office at Miami, FL (MFL) are collaborating on a project to investigate the impact of using high-resolution, 2-km Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature (SST) composites within the Weather Research and Forecasting (WRF) prediction system. The NWS MFL is currently running WRF in real-time to support daily forecast operations, using the National Centers for Environmental Prediction Nonhydrostatic Mesoscale Model dynamical core within the NWS Science and Training Resource Center's Environmental Modeling System (EMS) software. Twenty-seven hour forecasts are run daily initialized at 0300, 0900, 1500, and 2100 UTC on a domain with 4-km grid spacing covering the southern half of Florida and adjacent waters of the Gulf of Mexico and Atlantic Ocean. The SSTs are initialized with the NCEP Real-Time Global (RTG) analyses at 1/12deg resolution. The project objective is to determine whether more accurate specification of the lower-boundary forcing over water using the MODIS SST composites within the 4-km WRF runs will result in improved sea fluxes and hence, more accurate e\\olutiono f coastal mesoscale circulations and the associated sensible weather elements. SPoRT conducted parallel WRF EMS runs from February to August 2007 identical to the operational runs at NWS MFL except for the use of MODIS SST composites in place of the RTG product as the initial and boundary conditions over water. During the course of this evaluation, an intriguing case was examined from 6 May 2007, in which lake breezes and convection around Lake Okeechobee evolved quite differently when using the high-resolution SPoRT MODIS SST composites versus the lower-resolution RTG SSTs. This paper will analyze the differences in the 6 May simulations, as well as examine other cases from the summer 2007 in which the WRF

  3. Ge/Si Ratios as a Tracer of Hydrothermal Activity in the Nepal Himalaya

    Science.gov (United States)

    Evans, M. J.; Derry, L. A.

    2001-12-01

    Advection of deep-seated crustal rocks, high internal heat production, and rapid erosion of the thrust wedge result in steep thermal gradients in the crystalline rocks of the Himalayan front. Meteoric water circulation within these rocks produces geothermal activity in the deeply-incised river valleys near the Main Central Thrust shear zone. The springs have measured temperatures up to 70° C and TDS up to 8000 mg/L and drive significant anomalies in river chemistry. We have carried out a detailed study of the role of hot springs in the Narayani River basin of central Nepal (area 35,000 km2), the major drainage of the central Nepal Himalaya and a major tributary to the Ganges. In order to quantify the fluxes of heat and solutes from geothermal systems in the Narayani basin, the hydrothermal fluid flux must be estimated. As part of an ongoing effort to investigate the use of germanium-silicon systematics, we measured Ge/Si ratios in main stem, tributary and hot spring waters of the Narayani basin. While Ge/Si ratios in tributaries are similar to non-polluted world rivers (Iceland (9 to 150 μ mol/mol). The high Ge/Si ratios in the hot springs may reflect Rayleigh fractionation as low Ge/Si quartz is precipitated. The wide disparity in stream vs. hydrothermal values makes Ge/Si a valuable tool for quantifying hydrothermal fluid flux by mass balance. We can use a hydrothermal fluid flux estimate derived from the chemical mass balance to estimate convective heat loss in the Narayani basin. Preliminary estimates in the Marsyandi River yield a thermal power output rate of 200 MW, comparable with geothermal fields in the Taupo Volcanic Zone and when distributed over the spring affected area, yield a hydrothermal heat flow (160 mW/m2) comparable to continental heat flow and hydrothermal heat loss in the geothermal belt across Tibet. Fluxes of solutes and heat carried by Himalayan hot springs appear to be significant for Himalayan river chemistry and for thermal models of

  4. Spatial Distribution of b-value of the Copahue volcano during 2012-2014 eruptive period: Relationship between magmatic and hydrothermal system

    Science.gov (United States)

    Lazo, Jonathan; Basualto, Daniel; Bengoa, Cintia; Cardona, Carlos; Franco, Luis; Gil-Cruz, Fernando; Hernández, Erasmo; Lara, Luis; Lundgren, Paul; Medina, Roxana; Morales, Sergio; Peña, Paola; Quijada, Jonathan; Samsonov, Sergey; San Martin, Juan; Valderrama, Oscar

    2015-04-01

    Temporal and spatial variations of b-value have been interpreted as regional stress changes on active tectonic zones or magma ascent and/or hydrothermal fluids mobilization that could affect to active volcanic arc. Increasing of fluids pressure, medium heterogeneities or temperature changes would be the cause of these variations. The Copahue volcano is a shield strato-volcano that has been edified on the western margin of the Caviahue Caldera, located in the international border between Chile and Argentina, which contain an important geothermic field and is located at a horse-tail structure of the Liquiñe-Ofqui Fault Zone. The pre-fracture nature of its basement, as well as an extensive geothermic field, would be producing very complex conditions to fluids movement that could be exploring to use the 'b' value of the recorded seismicity between 2012 and 2014. Based in the database of VT seismic events, we used 2.073 events to calculate the b-value to obtain the 2D and 3D distribution maps. Results showed two anomalous zones: the first one located 9 Km to NE of the active crater, 3-6 Km depth, with high b-values (>1.2) that is associated with a very high production rate of small earthquakes that could suggest a brittle zone, located in the active geothermal field. The second zone, showed a low b-values (~ 0.7), located to east of the volcano edifice at volcano sitting on top of a geothermal system, the b-value offers a tool to understand the distribution of the seismic sources and hence a physical constrain for the coupled magmatic/hydrothermal system.

  5. The thermal and chemical evolution of hydrothermal vent fluids in shale hosted massive sulphide (SHMS) systems from the MacMillan Pass district (Yukon, Canada)

    Science.gov (United States)

    Magnall, J. M.; Gleeson, S. A.; Blamey, N. J. F.; Paradis, S.; Luo, Y.

    2016-11-01

    At Macmillan Pass (YT, Canada), the hydrothermal vent complexes beneath two shale-hosted massive sulphide (SHMS) deposits (Tom, Jason) are well preserved within Late Devonian strata. These deposits provide a unique opportunity to constrain key geochemical parameters (temperature, salinity, pH, fO2, ΣS) that are critical for metal transport and deposition in SHMS systems, and to evaluate the interaction between hydrothermal fluids and the mudstone host rock. This has been achieved using a combination of detailed petrography, isotopic techniques (δ34S, δ13C and δ18O values), carbonate rare earth element analysis (LA-ICP-MS), fluid inclusion analysis (microthermometry, gas analysis via incremental crush fast scan mass spectrometry), and thermodynamic modelling. Two main paragenetic stages are preserved in both vent complexes: Stage 1 comprises pervasive ankerite alteration of the organic-rich mudstone host rock and crosscutting stockwork ankerite veining (±pyrobitumen, pyrite and quartz) and; Stage 2 consists of main stage massive sulphide (galena-pyrrhotite-pyrite ± chalcopyrite-sphalerite) and siderite (±quartz and barytocalcite) mineralisation. Co-variation of δ18O and δ13C values in ankerite can be described by temperature dependent fractionation and fluid rock interaction. Together with fluid inclusion microthermometry, this provides evidence of a steep thermal gradient (from 300 to ∼100 °C) over approximately 15 m stratigraphic depth, temporally and spatially constrained within the paragenesis of both vent complexes and developed under shallow lithostatic (28), characteristic of diagenetic fluids, are coupled with positive europium anomalies and variable light REE depletion, which are more consistent with chloride complexation in hot (>250 °C) hydrothermal fluids. In this shallow sub-seafloor setting, thermal alteration of organic carbon in the immature, chemically reactive mudstones also had an important role in the evolution of fluid chemistry

  6. Mapping hydrothermally altered rocks at Cuprite, Nevada, using the advanced spaceborne thermal emission and reflection radiometer (Aster), a new satellite-imaging system

    Science.gov (United States)

    Rowan, L.C.; Hook, S.J.; Abrams, M.J.; Mars, J.C.

    2003-01-01

    The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a 14-band multispectral instrument on board the Earth Observing System (EOS), TERRA. The three bands between 0.52 and 0.86 ??m and the six bands from 1.60 and 2.43 ??m, which have 15- and 30-m spatial resolution, respectively, were selected primarily for making remote mineralogical determinations. The Cuprite, Nevada, mining district comprises two hydrothermal alteration centers where Tertiary volcanic rocks have been hydrothermally altered mainly to bleached silicified rocks and opalized rocks, with a marginal zone of limonitic argilized rocks. Country rocks are mainly Cambrian phyllitic siltstone and limestone. Evaluation of an ASTER image of the Cuprite district shows that spectral reflectance differences in the nine bands in the 0.52 to 2.43 ??m region provide a basis for identifying and mapping mineralogical components which characterize the main hydrothermal alteration zones: opal is the spectrally dominant mineral in the silicified zone; whereas, alunite and kaolinite are dominant in the opalized zone. In addition, the distribution of unaltered country rocks was mapped because of the presence of spectrally dominant muscovite in the siltstone and calcite in limestone, and the tuffaceous rocks and playa deposits were distinguishable due to their relatively flat spectra and weak absorption features at 2.33 and 2.20 ??m, respectively. An Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) image of the study area was processed using a similar methodology used with the ASTER data. Comparison of the ASTER and AVIRIS results shows that the results are generally similar, but the higher spectral resolution of AVIRIS (224 bands) permits identification of more individual minerals, including certain polymorphs. However, ASTER has recorded images of more than 90 percent of the Earth's land surface with less than 20 percent cloud cover, and these data are available at nominal or no cost

  7. Chemical reaction path modeling of hydrothermal processes on Mars: Preliminary results

    Science.gov (United States)

    Plumlee, Geoffrey S.; Ridley, W. Ian

    1992-01-01

    Hydrothermal processes are thought to have had significant roles in the development of surficial mineralogies and morphological features on Mars. For example, a significant proportion of the Martian soil could consist of the erosional products of hydrothermally altered impact melt sheets. In this model, impact-driven, vapor-dominated hydrothermal systems hydrothermally altered the surrounding rocks and transported volatiles such as S and Cl to the surface. Further support for impact-driven hydrothermal alteration on Mars was provided by studies of the Ries crater, Germany, where suevite deposits were extensively altered to montmorillonite clays by inferred low-temperature (100-130 C) hydrothermal fluids. It was also suggested that surface outflow from both impact-driven and volcano-driven hydrothermal systems could generate the valley networks, thereby eliminating the need for an early warm wet climate. We use computer-driven chemical reaction path calculation to model chemical processes which were likely associated with postulated Martian hydrothermal systems.

  8. Partitioning and Leaching Behavior of Actinides and Rare Earth Elements in a Zirconolite- Bearing Hydrothermal Vein System

    International Nuclear Information System (INIS)

    Payne, Timothy E.; Hart, Kaye P.; Lumpkin, Gregory R.; McGlinn, Peter J.; Giere, Reto

    2007-01-01

    Chemical extraction techniques and scanning electron microscopy were used to study the distribution and behavior of actinides and rare earth elements (REE) in hydrothermal veins at Adamello (Italy). The six samples discussed in this paper were from the phlogopite zone, which is one of the major vein zones. The samples were similar in their bulk chemical composition, mineralogy, and leaching behavior of major elements (determined by extraction with 9 M HCl). However, there were major differences in the extractability of REE and actinides. The most significant influence on the leaching characteristics appears to be the amounts of U, Th and REE incorporated in resistant host phases (zirconolite and titanite) rather than readily leached phases (such as apatite). Uranium and Th are very highly enriched in zirconolite grains. Actinides were more readily leached from samples with a higher content of U and Th, relative to the amount of zirconium. The results show that REE and actinides present in chemically resistant host minerals can be retained under aggressive leaching conditions. (authors)

  9. Template-directed hydrothermal synthesis of hydroxyapatite as a drug delivery system for the poorly water-soluble drug carvedilol

    Science.gov (United States)

    Zhao, Qinfu; Wang, Tianyi; Wang, Jing; Zheng, Li; Jiang, Tongying; Cheng, Gang; Wang, Siling

    2011-09-01

    In order to improve the dissolution rate and increase the bioavailability of a poorly water-soluble drug, intended to be administered orally, the biocompatible and bioactive mesoporous hydroxyapatite (HA) was successfully synthesized. In the present study, mesoporous HA nanoparticles were produced using Pluronic block co-polymer F127 and cetyltrimethylammonium bromide (CTAB) as templates by the hydrothermal method. The obtained mesoporous HA was employed as a drug delivery carrier to investigate the drug storage/release properties using carvedilol (CAR) as a model drug. Characterizations of the raw CAR powder, mesoporous HA and CAR-loaded HA were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, N2 adsorption/desorption, thermogravimetric analysis (TGA), and UV-VIS spectrophotometry. The results demonstrated that CAR was successfully incorporated into the mesoporous HA host. In vitro drug release studies showed that mesoporous HA had a high drug load efficiency and provided immediate release of CAR compared with micronized raw drug in simulated gastric fluid (pH 1.2) and intestinal fluid (pH 6.8). Consequently, mesoporous HA is a good candidate as a drug carrier for the oral delivery of poorly water-soluble drugs.

  10. Template-directed hydrothermal synthesis of hydroxyapatite as a drug delivery system for the poorly water-soluble drug carvedilol

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Qinfu [Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China); Wang Tianyi [Department of Clinical Pharmacy, School of Pharmacy, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China); Wang Jing [Department of Physical Chemistry, School of Basic Science, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China); Zheng Li; Jiang, Tongying; Cheng Gang [Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China); Wang Siling, E-mail: silingwang@syphu.edu.cn [Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang 110016 (China)

    2011-09-15

    In order to improve the dissolution rate and increase the bioavailability of a poorly water-soluble drug, intended to be administered orally, the biocompatible and bioactive mesoporous hydroxyapatite (HA) was successfully synthesized. In the present study, mesoporous HA nanoparticles were produced using Pluronic block co-polymer F127 and cetyltrimethylammonium bromide (CTAB) as templates by the hydrothermal method. The obtained mesoporous HA was employed as a drug delivery carrier to investigate the drug storage/release properties using carvedilol (CAR) as a model drug. Characterizations of the raw CAR powder, mesoporous HA and CAR-loaded HA were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, N{sub 2} adsorption/desorption, thermogravimetric analysis (TGA), and UV-VIS spectrophotometry. The results demonstrated that CAR was successfully incorporated into the mesoporous HA host. In vitro drug release studies showed that mesoporous HA had a high drug load efficiency and provided immediate release of CAR compared with micronized raw drug in simulated gastric fluid (pH 1.2) and intestinal fluid (pH 6.8). Consequently, mesoporous HA is a good candidate as a drug carrier for the oral delivery of poorly water-soluble drugs.

  11. Template-directed hydrothermal synthesis of hydroxyapatite as a drug delivery system for the poorly water-soluble drug carvedilol

    International Nuclear Information System (INIS)

    Zhao Qinfu; Wang Tianyi; Wang Jing; Zheng Li; Jiang, Tongying; Cheng Gang; Wang Siling

    2011-01-01

    In order to improve the dissolution rate and increase the bioavailability of a poorly water-soluble drug, intended to be administered orally, the biocompatible and bioactive mesoporous hydroxyapatite (HA) was successfully synthesized. In the present study, mesoporous HA nanoparticles were produced using Pluronic block co-polymer F127 and cetyltrimethylammonium bromide (CTAB) as templates by the hydrothermal method. The obtained mesoporous HA was employed as a drug delivery carrier to investigate the drug storage/release properties using carvedilol (CAR) as a model drug. Characterizations of the raw CAR powder, mesoporous HA and CAR-loaded HA were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, N 2 adsorption/desorption, thermogravimetric analysis (TGA), and UV-VIS spectrophotometry. The results demonstrated that CAR was successfully incorporated into the mesoporous HA host. In vitro drug release studies showed that mesoporous HA had a high drug load efficiency and provided immediate release of CAR compared with micronized raw drug in simulated gastric fluid (pH 1.2) and intestinal fluid (pH 6.8). Consequently, mesoporous HA is a good candidate as a drug carrier for the oral delivery of poorly water-soluble drugs.

  12. Complexing and hydrothermal ore deposition

    CERN Document Server

    Helgeson, Harold C

    1964-01-01

    Complexing and Hydrothermal Ore Deposition provides a synthesis of fact, theory, and interpretative speculation on hydrothermal ore-forming solutions. This book summarizes information and theory of the internal chemistry of aqueous electrolyte solutions accumulated in previous years. The scope of the discussion is limited to those aspects of particular interest to the geologist working on the problem of hydrothermal ore genesis. Wherever feasible, fundamental principles are reviewed. Portions of this text are devoted to calculations of specific hydrothermal equilibriums in multicompone

  13. Petrologic and stable isotopic studies of a fossil hydrothermal system in ultramafic environment (Chenaillet ophicalcites, Western Alps, France): Processes of carbonate cementation

    Science.gov (United States)

    Lafay, Romain; Baumgartner, Lukas P.; Stephane, Schwartz; Suzanne, Picazo; German, Montes-Hernandez; Torsten, Vennemann

    2017-12-01

    The Late Jurassic Chenaillet ophiolitic complex (Western Alps) represents parts of an oceanic core-complex of the Liguria-Piemonte domain. A model for the origin and evolution of the Chenaillet ophicalcites based on textural and isotopic characterization is presented. The Chenaillet ophicalcites correspond to brecciated serpentinized peridotites that record seafloor shallow serpentinization at a minimum temperatures of 150 °C followed by authigenic carbonation. Carbonation starts with a network of micrometric to millimetric pre- or syn-clast formation calcite veins accompanied by a pervasive carbonation of residual olivine and serpentine inside the serpentinite mesh core. A matrix of small calcite (values that range between - 5‰ and + 0.4‰. The lower values were obtained for calcite within the serpentinite clasts. The δ18O (VSMOW) values have a range between + 11‰ and + 16‰ in carbonated clasts. The δ18O values in the matrix are fairly homogeneous with an average at + 12‰ and the late calcite veins have values between + 12.5 and + 15.5‰. These values suggest a relatively high temperature of formation for all the carbonates. Carbonates within clast are mainly characterized by a formation temperature in the range of 110 °C to 180 °C assuming a δ18O value of seawater of 0‰, the matrix forms at a temperature of ca. 165 °C. Late veins are characterized by a formation temperature ranging between 120and 155 °C. We propose a model where serpentinization is followed by discrete carbonation then brecciation and cementation as a consequence of continuous hydrothermal fluid circulation in the serpentinite basement. This is comparable to observations made in the stockwork of present-day long-lived oceanic hydrothermal systems.

  14. Double-diffusive convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability

    Energy Technology Data Exchange (ETDEWEB)

    Vincze, Miklos; Borcia, Ion; Harlander, Uwe [Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology (BTU) Cottbus-Senftenberg, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Gal, Patrice Le, E-mail: vincze.m@lecso.elte.hu [Institut de Recherche sur les Phénomènes Hors Equilibre, CNRS—Aix-Marseille University—Ecole Centrale Marseille, 49 rue F. Joliot-Curie, F-13384 Marseille (France)

    2016-12-15

    A water-filled differentially heated rotating annulus with initially prepared stable vertical salinity profiles is studied in the laboratory. Based on two-dimensional horizontal particle image velocimetry data and infrared camera visualizations, we describe the appearance and the characteristics of the baroclinic instability in this original configuration. First, we show that when the salinity profile is linear and confined between two non-stratified layers at top and bottom, only two separate shallow fluid layers can be destabilized. These unstable layers appear nearby the top and the bottom of the tank with a stratified motionless zone between them. This laboratory arrangement is thus particularly interesting to model geophysical or astrophysical situations where stratified regions are often juxtaposed to convective ones. Then, for more general but stable initial density profiles, statistical measures are introduced to quantify the extent of the baroclinic instability at given depths and to analyze the connections between this depth-dependence and the vertical salinity profiles. We find that, although the presence of stable stratification generally hinders full-depth overturning, double-diffusive convection can lead to development of multicellular sideways convection in shallow layers and subsequently to a multilayered baroclinic instability. Therefore we conclude that by decreasing the characteristic vertical scale of the flow, stratification may even enhance the formation of cyclonic and anticyclonic eddies (and thus, mixing) in a local sense. (paper)

  15. Double-diffusive convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability

    International Nuclear Information System (INIS)

    Vincze, Miklos; Borcia, Ion; Harlander, Uwe; Gal, Patrice Le

    2016-01-01

    A water-filled differentially heated rotating annulus with initially prepared stable vertical salinity profiles is studied in the laboratory. Based on two-dimensional horizontal particle image velocimetry data and infrared camera visualizations, we describe the appearance and the characteristics of the baroclinic instability in this original configuration. First, we show that when the salinity profile is linear and confined between two non-stratified layers at top and bottom, only two separate shallow fluid layers can be destabilized. These unstable layers appear nearby the top and the bottom of the tank with a stratified motionless zone between them. This laboratory arrangement is thus particularly interesting to model geophysical or astrophysical situations where stratified regions are often juxtaposed to convective ones. Then, for more general but stable initial density profiles, statistical measures are introduced to quantify the extent of the baroclinic instability at given depths and to analyze the connections between this depth-dependence and the vertical salinity profiles. We find that, although the presence of stable stratification generally hinders full-depth overturning, double-diffusive convection can lead to development of multicellular sideways convection in shallow layers and subsequently to a multilayered baroclinic instability. Therefore we conclude that by decreasing the characteristic vertical scale of the flow, stratification may even enhance the formation of cyclonic and anticyclonic eddies (and thus, mixing) in a local sense. (paper)

  16. Oxygen isotope exchange kinetics of mineral pairs in closed and open systems: Applications to problems of hydrothermal alteration of igneous rocks and Precambrian iron formations

    Science.gov (United States)

    Gregory, R.T.; Criss, R.E.; Taylor, H.P.

    1989-01-01

    The systematics of stable-isotope exchange between minerals and fluids are examined in the context of modal mineralogical variations and mass-balance considerations, both in closed and in open systems. On mineral-pair ??18O plots, samples from terranes that have exchanged with large amounts of fluid typically map out steep positively-sloped non-equilibrium arrays. Analytical models are derived to explain these effects; these models allow for different exchange rates between the various minerals and the external fluids, as well as different fluid fluxes. The steep arrays are adequately modelled by calculated isochron lines that involve the whole family of possible exchange trajectories. These isochrons have initially-steep near-vertical positive slopes that rotate toward a 45?? equilibrium slope as the exchange process proceeds to completion. The actual data-point array is thus analogous to the hand of an "isotopic clock" that measures the duration of the hydrothermal episode. The dimensionless ratio of the volumetric fluid flux to the kinetic rate parameter ( u k) determines the shape of each individual exchange trajectory. In a fluid-buffered system ( u k ??? 1), the solutions to the equations: (1) are independent of the mole fractions of the solid phases; (2) correspond to Taylor's open-system water/rock equation; and (3) yield straight-line isochrons that have slopes that approach 1 f, where f is the fraction reacted of the more sluggishly exchanging mineral. The isochrons for this simple exchange model are closely congruent with the isochrons calculated for all of the more complex models, thereby simplifying the application of theory to actual hydrothermal systems in nature. In all of the models an order of magnitude of time (in units of kt) separates steep non-equilibrium arrays (e.g., slope ??? 10) from arrays approaching an equilibrium slope of unity on a ??-?? diagram. Because we know the approximate lifetimes of many hydrothermal systems from geologic and

  17. Hydrothermal conversion of biomass

    NARCIS (Netherlands)

    Knezevic, D.

    2009-01-01

    This thesis presents research of hydrothermal conversion of biomass (HTC). In this process, hot compressed water (subcritical water) is used as the reaction medium. Therefore this technique is suitable for conversion of wet biomass/ waste streams. By working at high pressures, the evaporation of

  18. Carbon dots: Synthesis from renewable sources via hydrothermal carbonization, characterization and evaluation of their interaction with biological systems

    International Nuclear Information System (INIS)

    Moraes, Liz Specian de; Alves, Oswaldo Luiz

    2016-01-01

    Full text: Carbon dots (CDs) constitute a new class of carbon-based nanomaterials with interesting photoluminescent properties that enable their potential use in bioimaging, sensing and drug delivery applications. They consist of quasi spherical nanoparticles with size below 10 nm. As a consequence of their low toxicity and biocompatibility, CDs have been considered as a promising alternative to traditional semiconductor-based quantum dots. In addition, they can be synthesized from accessible renewable sources in an environmentally friendly perspective. In this work, we report the use of bovine serum albumin (BSA) and bovine plasma (BP) as precursors to synthesis of CDs applying hydrothermal carbonization method. The study also includes the physical chemical characterization and the evaluation of interaction between these nanomaterials and biosystems, using hemolytic assay. The morphology and size of the carbon nanoparticles were analyzed by Transmission Electronic Microscopy. CDs obtained from BSA (BSA-CDs) and BP (BP-CDs) had spherical shape with an average size of 5.6 and 3.7 nm, respectively. The fluorescence quantum yield was calculated using quinine sulfate as reference. BSA-CDs and BP-CDs exhibited quantum yields of 4.9% and 4.0%, when they were excited at wavelength of 315 and 300 nm, respectively. Furthermore, the red-shift phenomenon was observed in the emission spectra of both synthesized CDs, indicating the formation of particles with different sizes or the presence of surface energy traps distribution. The composition of CDs was determined by Elemental Analysis and X-ray Photoelectron Spectroscopy. Both nanomaterials contained C, N, O and S elements. The hemolytic assay demonstrated the synthesized CDs did not cause damage to red blood cell membrane at concentrations between 5 and 250 μg mL -1 . (author)

  19. Carbon dots: Synthesis from renewable sources via hydrothermal carbonization, characterization and evaluation of their interaction with biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Moraes, Liz Specian de; Alves, Oswaldo Luiz, E-mail: liz.specian@hotmail.com.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2016-07-01

    Full text: Carbon dots (CDs) constitute a new class of carbon-based nanomaterials with interesting photoluminescent properties that enable their potential use in bioimaging, sensing and drug delivery applications. They consist of quasi spherical nanoparticles with size below 10 nm. As a consequence of their low toxicity and biocompatibility, CDs have been considered as a promising alternative to traditional semiconductor-based quantum dots. In addition, they can be synthesized from accessible renewable sources in an environmentally friendly perspective. In this work, we report the use of bovine serum albumin (BSA) and bovine plasma (BP) as precursors to synthesis of CDs applying hydrothermal carbonization method. The study also includes the physical chemical characterization and the evaluation of interaction between these nanomaterials and biosystems, using hemolytic assay. The morphology and size of the carbon nanoparticles were analyzed by Transmission Electronic Microscopy. CDs obtained from BSA (BSA-CDs) and BP (BP-CDs) had spherical shape with an average size of 5.6 and 3.7 nm, respectively. The fluorescence quantum yield was calculated using quinine sulfate as reference. BSA-CDs and BP-CDs exhibited quantum yields of 4.9% and 4.0%, when they were excited at wavelength of 315 and 300 nm, respectively. Furthermore, the red-shift phenomenon was observed in the emission spectra of both synthesized CDs, indicating the formation of particles with different sizes or the presence of surface energy traps distribution. The composition of CDs was determined by Elemental Analysis and X-ray Photoelectron Spectroscopy. Both nanomaterials contained C, N, O and S elements. The hemolytic assay demonstrated the synthesized CDs did not cause damage to red blood cell membrane at concentrations between 5 and 250 μg mL{sup -1}. (author)

  20. Burkholderia insulsa sp. nov., a facultatively chemolithotrophic bacterium isolated from an arsenic-rich shallow marine hydrothermal system.

    Science.gov (United States)

    Rusch, Antje; Islam, Shaer; Savalia, Pratixa; Amend, Jan P

    2015-01-01

    Enrichment cultures inoculated with hydrothermally influenced nearshore sediment from Papua New Guinea led to the isolation of an arsenic-tolerant, acidophilic, facultatively aerobic bacterial strain designated PNG-April(T). Cells of this strain were Gram-stain-negative, rod-shaped, motile and did not form spores. Strain PNG-April(T) grew at temperatures between 4 °C and 40 °C (optimum 30-37 °C), at pH 3.5 to 8.3 (optimum pH 5-6) and in the presence of up to 2.7% NaCl (optimum 0-1.0%). Both arsenate and arsenite were tolerated up to concentrations of at least 0.5 mM. Metabolism in strain PNG-April(T) was strictly respiratory. Heterotrophic growth occurred with O2 or nitrate as electron acceptors, and aerobic lithoautotrophic growth was observed with thiosulfate or nitrite as electron donors. The novel isolate was capable of N2-fixation. The respiratory quinones were Q-8 and Q-7. Phylogenetically, strain PNG-April(T) belongs to the genus Burkholderia and shares the highest 16S rRNA gene sequence similarity with the type strains of Burkholderia fungorum (99.8%), Burkholderia phytofirmans (98.8%), Burkholderia caledonica (98.4%) and Burkholderia sediminicola (98.4%). Differences from these related species in several physiological characteristics (lipid composition, carbohydrate utilization, enzyme profiles) and DNA-DNA hybridization suggested the isolate represents a novel species of the genus Burkholderia, for which we propose the name Burkholderia insulsa sp. nov. The type strain is PNG-April(T) ( = DSM 28142(T) = LMG 28183(T)). © 2015 IUMS.

  1. Late-stage anhydrite-gypsum-siderite-dolomite-calcite assemblages record the transition from a deep to a shallow hydrothermal system in the Schwarzwald mining district, SW Germany

    Science.gov (United States)

    Burisch, Mathias; Walter, Benjamin F.; Gerdes, Axel; Lanz, Maximilian; Markl, Gregor

    2018-02-01

    The majority of hydrothermal vein systems of economic interest occur at relatively shallow crustal levels, although many of them formed at significantly greater depths. Their present position is a consequence of uplift and erosion. Although, many aspects of their formation are well constrained, the temporal chemical evolution of such systems during uplift and erosion is still poorly understood. These vein minerals comprise calcite, dolomite-ankerite, siderite-magnesite, anhydrite and gypsum forming the last gangue assemblages in Jurassic and Tertiary sulphide-fluorite-quartz-barite veins of the Schwarzwald mining district, SW Germany. Mineral textures of samples from nine localities reveal that in these sequences, mineral precipitation follows a recurring pattern: early calcite is followed by anhydrite or gypsum, siderite and/or dolomite. This succession may repeat up to three times. In-situ (LA-ICP-MS) U-Pb age dating of 15 carbonates from three subsequent generations of the late-stage vein assemblage yield robust ages between 20 and 0.6 Ma. Each mineral sequence forms in a distinctive period of about 2-5 Ma. These ages clearly relate these late-stage mineral phases to the youngest geological episode of the Schwarzwald, which is associated with the Cenozoic Rhine Graben rifting and basement uplift. Based on thermodynamic modelling, the formation of the observed mineral assemblages required an deeply sourced Mg-, Fe- and SO4-rich fluid (b), which was episodically mixed with a shallow crustal HCO3-rich fluid (a). As a consequence of fluid mixing, concentrations of Mg, Fe and SO4 temporarily increased and initiated the formation of the observed sulphate-carbonate mineral sequences. This discontinuous large-scale vertical fluid mixing was presumably directly related to episodes of active tectonics associated with the Cenozoic strike-slip regime of the Upper Rhine Graben. Analogously, episodic fluid mixing is a major key in the formation of older (Jurassic to early

  2. Variability of Oceanic Mesoscale Convective System Vertical Structures Observed by CloudSat in Indo-Pacific Regions Associated with the Madden-Julian Oscillation

    Science.gov (United States)

    Yuan, J.

    2016-12-01

    Vertical structures of mesoscale convective systems (MCSs) during the Madden-Julian-Oscillation (MJO) are investigated using 2006-2011 CloudSat radar measurements for Indo-Pacific oceanic areas. In active phases of the MJO relatively more large MCSs and connected MCSs occur. The frequency of occurrence of connected MCSs peaks in the onset phase, a phase earlier than separated MCSs. Compared to separated MCSs, connected MCSs in all sizes have weaker reflectivity above 8 km in their deep precipitating portions and thick anvil clouds closely linked to them, suggesting more "stratiform" physics associated with them. Separated MCSs and connected MCSs together produce relatively the least anvil clouds in the onset phase while their deep precipitating portions show stronger/weaker reflectivity above 8 km before/after the onset phase. Thus after the onset phase of the MJO, MCSs shift toward more "convective" organization because separated MCSs maximize after the onset, while their internal structures appear more "stratiform" because internally they have weaker reflectivity above 8km. Connected MCSs coincide with a more humid middle troposphere spatially, even at the same places a few days before they occur. Middle-tropospheric moistening peaks in the onset phase. Moistening of the free troposphere around deep convective systems shows relatively stronger moistening/drying below the 700 hPa before/after the onset phase compared to domain-mean averages. Lower-topped clouds occur most frequently around CMCSs and in active phases, consistent with the presence of a moister free troposphere. Coexistence of these phenomena suggests that the role of middle troposphere moisture in the formation of CMCSs needs to be better understood.

  3. Hydrothermal processing of radioactive combustible waste

    International Nuclear Information System (INIS)

    Worl, L.A.; Buelow, S.J.; Harradine, D.; Le, L.; Padilla, D.D.; Roberts, J.H.

    1998-01-01

    Hydrothermal processing has been demonstrated for the treatment of radioactive combustible materials for the US Department of Energy. A hydrothermal processing system was designed, built and tested for operation in a plutonium glovebox. Presented here are results from the study of the hydrothermal oxidation of plutonium and americium contaminated organic wastes. Experiments show the destruction of the organic component to CO 2 and H 2 O, with 30 wt.% H 2 O 2 as an oxidant, at 540 C and 46.2 MPa. The majority of the actinide component forms insoluble products that are easily separated by filtration. A titanium liner in the reactor and heat exchanger provide corrosion resistance for the oxidation of chlorinated organics. The treatment of solid material is accomplished by particle size reduction and the addition of a viscosity enhancing agent to generate a homogeneous pumpable mixture

  4. The BGU/CERN solar hydrothermal reactor

    CERN Document Server

    Bertolucci, Sergio; Caspers, Fritz; Garb, Yaakov; Gross, Amit; Pauletta, Stefano

    2014-01-01

    We describe a novel solar hydrothermal reactor (SHR) under development by Ben Gurion University (BGU) and the European Organization for Nuclear Research CERN. We describe in broad terms the several novel aspects of the device and, by extension, of the niche it occupies: in particular, enabling direct off-grid conversion of a range of organic feedstocks to sterile useable (solid, liquid) fuels, nutrients, products using only solar energy and water. We then provide a brief description of the high temperature high efficiency panels that provide process heat to the hydrothermal reactor, and review the basics of hydrothermal processes and conversion taking place in this. We conclude with a description of a simulation of the pilot system that will begin operation later this year.

  5. Southern Ocean Convection and tropical telleconnections

    Science.gov (United States)

    Marinov, I.; Cabre, A.; Gnanadesikan, A.

    2014-12-01

    We show that Southern Ocean (SO) temperatures in the latest generation of Earth System Models exhibit two major modes of variation, one driven by deep convection, the other by tropical variability. We perform a CMIP5 model intercomparison to understand why different climate models represent SO variability so differently in long, control simulations. We show that multiyear variability in Southern Ocean sea surface temperatures (SSTs) can in turn influence oceanic and atmospheric conditions in the tropics on short (atmospheric) time-scales. We argue that the strength and pattern of SO-tropical teleconnections depends on the intensity of SO deep convection. Periodic convection in the SO is a feature of most CMIP5 models under preindustrial forcing (deLavergne et al., 2014). Models show a wide distribution in the spatial extent, periodicity and intensity of their SO convection, with some models convecting most of the time, and some showing very little convection. In a highly convective coupled model, we find that multidecadal variability in SO and global SSTs, as well as SO heat storage are driven by Weddell Sea convective variability, with convective decades relatively warm due to the heat released from the deep southern ocean and non-convective decades cold due to the subsurface storage of heat. Furthermore, pulses of SO convection drive SST and sea ice variations, influencing absorbed shortwave and emitted longwave radiation, wind, cloud and precipitation patterns, with climatic implications for the low latitudes via fast atmospheric teleconnections. We suggest that these high-low latitude teleconnection mechanisms are relevant for understanding hiatus decades. Additionally, Southern Ocean deep convection varied significantly during past, natural climate changes such as during the last deglaciation. Weddell Sea open convection was recently weakened, likely as a consequence of anthropogenic forcing and the resulting surface freshening. Our study opens up the

  6. Integrated 3D Geological Modeling to Gain Insight in the Effects of Hydrothermal Alteration on Post-Ore Deformation Style and Strain Localization in the Flin Flon Volcanogenic Massive Sulfide Ore System

    Directory of Open Access Journals (Sweden)

    Ernst Schetselaar

    2017-12-01

    Full Text Available 3D geological modeling of lithogeochemical and geological data provides insight into the role of the sulfide ore horizon and associated footwall hydrothermal alteration in localizing shear strain in the Flin Flon volcanogenic massive sulfide deposits, Canada, as deformation evolved from brittle-ductile to ductile regimes during collisional stages of the 1.9–1.8 Ga Trans-Hudson orogeny. 3D spatial characterization of hydrothermal alteration based on the Ishikawa index (AI and normative corundum percentages outline sericite + chlorite-rich high strain zones, consisting of Al-enriched and Na-depleted felsic and mafic volcanic rocks in the footwall of the sulfide ore horizon. The hydrothermal vent complex, from which these sheared alteration zones originated, was stacked together with the ore horizon by W-vergent thrust faults during an early collisional deformation regime, imbricating molasse-type clastic sediments with the ore-hosting volcanic and volcaniclastic rocks of the Flin Flon arc assemblage. Chlorite-rich planar zones marked by high values of the Carbonate–chlorite–pyrite index (CCPI are laterally more extensive and outline a later system of ductile shear zones, in which phyllosilicates, quartz and chalcopyrite in stringer zones localized shear strain and enhanced transposition of the hydrothermal vent stockwork. The contrasting deformation styles of these two thrusting events and their localization within the ore horizon and hydrothermal vent stockwork have important implications for vectoring towards undiscovered ore in this mature mining camp that are possibly also relevant to other strongly deformed VMS ore systems.

  7. Inferences on the hydrothermal system beneath the resurgent dome in Long Valley Caldera, east-central California, USA, from recent pumping tests and geochemical sampling

    Science.gov (United States)

    Farrar, Christopher D.; Sorey, Michael L.; Roeloffs, Evelyn; Galloway, Devin L.; Howle, James F.; Jacobson, Ronald

    2003-10-01

    Quaternary volcanic unrest has provided heat for episodic hydrothermal circulation in the Long Valley caldera, including the present-day hydrothermal system, which has been active over the past 40 kyr. The most recent period of crustal unrest in this region of east-central California began around 1980 and has included periods of intense seismicity and ground deformation. Uplift totaling more than 0.7 m has been centered on the caldera's resurgent dome, and is best modeled by a near-vertical ellipsoidal source centered at depths of 6-7 km. Modeling of both deformation and microgravity data now suggests that (1) there are two inflation sources beneath the caldera, a shallower source 7-10 km beneath the resurgent dome and a deeper source ˜15 km beneath the caldera's south moat and (2) the shallower source may contain components of magmatic brine and gas. The Long Valley Exploration Well (LVEW), completed in 1998 on the resurgent dome, penetrates to a depth of 3 km directly above this shallower source, but bottoms in a zone of 100°C fluid with zero vertical thermal gradient. Although these results preclude extrapolations of temperatures at depths below 3 km, other information obtained from flow tests and fluid sampling at this well indicates the presence of magmatic volatiles and fault-related permeability within the metamorphic basement rocks underlying the volcanic fill. In this paper, we present recently acquired data from LVEW and compare them with information from other drill holes and thermal springs in Long Valley to delineate the likely flow paths and fluid system properties under the resurgent dome. Additional information from mineralogical assemblages in core obtained from fracture zones in LVEW documents a previous period of more vigorous and energetic fluid circulation beneath the resurgent dome. Although this system apparently died off as a result of mineral deposition and cooling (and/or deepening) of magmatic heat sources, flow testing and tidal

  8. Seismo-acoustic evidence for an avalanche driven phreatic eruption through a beheaded hydrothermal system: An example from the 2012 Tongariro eruption

    Science.gov (United States)

    Jolly, A.D.; Jousset, P.; Lyons, J.J.; Carniel, R.; Fournier, R.; Fry, B.; Miller, C.

    2016-01-01

    The 6 August 2012 Te Maari eruption comprises a complex eruption sequence including multiple eruption pulses, a debris avalanche that propagated ~ 2 km from the vent, and the formation of a 500 m long, arcuate chasm, located ~ 300 m from the main eruption vent. The eruption included 6 distinct impulses that were coherent across a local infrasound network marking the eruption onset at 11:52:18 (all times UTC). An eruption energy release of ~ 3 × 1012 J was calculated using a body wave equation for radiated seismic energy. A similar calculation based on the infrasound record, shows that ~ 90% of the acoustic energy was released from three impulses at onset times 11:52:20 (~ 20% of total eruption energy), 11:52:27 (~ 50%), and 11:52:31 (~ 20%). These energy impulses may coincide with eyewitness accounts describing an initial eastward directed blast, followed by a westward directed blast, and a final vertical blast. Pre-eruption seismic activity includes numerous small unlocatable micro-earthquakes that began at 11:46:50. Two larger high frequency earthquakes were recorded at 11:49:06 and 11:49:21 followed directly by a third earthquake at 11:50:17. The first event was located within the scarp based on an arrival time location from good first P arrival times and probably represents the onset of the debris avalanche. The third event was a tornillo, characterised by a 0.8 Hz single frequency resonance, and has a resonator attenuation factor of Q ~ 40, consistent with a bubbly fluid filled resonator. This contrasts with a similar tornillo event occurring 2.5 weeks earlier having Q ~ 250–1000, consistent with a dusty gas charged resonator. We surmise from pre-eruption seismicity, and the observed attenuation change, that the debris avalanche resulted from the influx of fluids into the hydrothermal system, causing destabilisation and failure. The beheaded hydrothermal system may have then caused depressurisation frothing of the remaining gas charged system leading to the

  9. The response of a simulated mesoscale convective system to increased aerosol pollution: Part II: Derecho characteristics and intensity in response to increased pollution

    Science.gov (United States)

    Clavner, Michal; Grasso, Lewis D.; Cotton, William R.; van den Heever, Susan C.

    2018-01-01

    Mesoscale Convective Systems (MCS) are important contributors to rainfall as well as producers of severe weather such as hail, tornados, and straight-line wind events known as derechos. In this study, different aerosol concentrations and their effects on a derecho event are examined by simulating a case study, the 8 May 2009 "Super-Derecho", using the Regional Atmospheric Modeling System (RAMS), a cloud-resolving model with sophisticated aerosol and cloud microphysics. Three simulations were conducted that differed in the initial aerosol concentrations, spatial distribution and chemical composition as derived from output of GEOS-Chem, a 3D chemical transport model. In order to understand the impact of changes in aerosol concentrations on the derecho characteristics, the dynamical processes that produced the strong surface wind were determined by performing back-trajectory analysis during two periods of the simulated storm: the development and the onset of dissipation. A time dependent and non-monotonic trend was found between the intensity of the derecho and the increased aerosol concentrations that served as cloud condensation nuclei. During the formation period of the MCS, the non-monotonic trend was attributed to the microphysical impact of aerosol loading on the intensity of the cold pool; that is, the impact of aerosols on both the melting and evaporation rates of hydrometeors. The subsequent intensity changes within the cold pool modified the balance between the horizontal vorticity generated by the cold pool and that of the environment, thereby impacting the orientation of the convective updraft at the leading line. This, in turn, altered the primary flow that contributed to the formation of the derecho-strength surface winds. The simulation with no anthropogenic aerosols exhibited the strongest cold pool and the primary flow was associated with a descending rear inflow jet that produced the derecho winds over a larger region. The simulation with the highest

  10. The Relationship Between Latent Heating, Vertical Velocity, and Precipitation Processes: the Impact of Aerosols on Precipitation in Organized Deep Convective Systems

    Science.gov (United States)

    Tao, Wei-Kuo; Li, Xiaowen

    2016-01-01

    A high-resolution, two-dimensional cloud-resolving model with spectral-bin microphysics is used to study the impact of aerosols on precipitation processes in both a tropical oceanic and a midlatitude continental squall line with regard to three processes: latent heating (LH), cold pool dynamics, and ice microphysics. Evaporative cooling in the lower troposphere is found to enhance rainfall in low cloud condensation nuclei (CCN) concentration scenarios in the developing stages of a midlatitude convective precipitation system. In contrast, the tropical case produced more rainfall under high CCN concentrations. Both cold pools and low-level convergence are stronger for those configurations having enhanced rainfall. Nevertheless, latent heat release is stronger (especially after initial precipitation) in the scenarios having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH, and precipitation processes. The results show that evaporative cooling is important for cold pool strength and rain enhancement in both cases. However, ice microphysics play a larger role in the midlatitude case compared to the tropics. Detailed analysis of the vertical velocity-governing equation shows that temperature buoyancy can enhance updraftsdowndrafts in the middlelower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is of the same order and acts in the opposite direction. Water loading is small but of the same order as the net PGF-temperature buoyancy forcing. The balance among these terms determines the intensity of convection.

  11. Novel barite chimneys at the Loki´s Castle Vent Field shed light on key factors shaping microbial communities and functions in hydrothermal systems

    Directory of Open Access Journals (Sweden)

    Ida Helene eSteen

    2016-01-01

    Full Text Available In order to fully understand the cycling of elements in hydrothermal systems it is critical to understand intra-field variations in geochemical and microbiological processes in both focused, high-temperature and diffuse, low-temperature areas. To reveal important causes and effects of this variation, we performed an extensive chemical and microbiological characterization of a low-temperature venting area in the Loki’s Castle Vent Field (LCVF. This area, located at the flank of the large sulfide mound, is characterized by numerous chimney-like barite (BaSO4 structures (≤ 1m high covered with white cotton-like microbial mats. Results from geochemical analyses, microscopy (FISH, SEM, 16S rRNA gene amplicon-sequencing and metatranscriptomics were compared to results from previous analyses of biofilms growing on black smoker chimneys at LCVF. Based on our results, we constructed a conceptual model involving the geochemistry and microbiology in the LCVF. The model suggests that CH4 and H2S are important electron donors for microorganisms in both high-temperature and low-temperature areas, whereas the utilization of H2 seems restricted to high-temperature areas. This further implies that sub-seafloor processes can affect energy-landscapes, elemental cycling, and the metabolic activity of primary producers on the seafloor. In the cotton-like microbial mats on top of the active barite chimneys, a unique network of single cells of Epsilonproteobacteria interconnected by threads of extracellular polymeric substances (EPS was seen, differing significantly from the long filamentous Sulfurovum filaments observed in biofilms on the black smokers. This network also induced nucleation of barite crystals and is suggested to play an essential role in the formation of the microbial mats and the chimneys. Furthermore, it illustrates variations in how different genera of Epsilonproteobacteria colonize and position cells in different vent fluid mixing zones within

  12. Structural Characteristics of Nocturnal Mesoscale Convective Systems in the U.S. Great Plains as Observed During the PECAN Field Campaign

    Science.gov (United States)

    Bodine, D. J.; Dougherty, E.; Rasmussen, K. L.; Torres, A. D.

    2015-12-01

    During the summer in the U.S. Great Plains, some of the heaviest precipitation falls from large thunderstorm complexes known as Mesoscale Convective Systems (MCSs). These frequently occurring MCSs are often nocturnal in nature, so the dynamics associated with these systems are more elusive than those in the daytime. The Plains Elevated Convection at Night (PECAN) field campaign was launched over a 7-week period as an endeavor to better understand nocturnal MCSs occurring in the Great Plains. PECAN featured a dense array of ground-based and airborne instruments to observe nocturnal MCS, including dual-polarization radars at multiple frequencies, mobile mesonets, and sounding units. Our role in PECAN involved deploying Ott Parsivel disdrometers to gain information on drop size distributions (DSDs) and fall speeds. Analysis of disdrometer data in conjunction with radar data presented using Contour Frequency by Altitude Diagrams (CFADs) and high-resolution radiosonde data allows for a structural comparison of PECAN MCS cases to previously identified MCS archetypes. Novel insights into the structural evolution of nocturnal MCSs in relation to their synoptic, mesoscale, and thermodynamic environments are presented, using data collected from dense and numerous observation platforms. Understanding the environmental conditions that result in different nocturnal MCS configurations is useful for gaining insight into precipitation distributions and potential severe weather and flooding hazards in the Great Plains.

  13. Artificial intelligence systems for rainy areas detection and convective cells' delineation for the south shore of Mediterranean Sea during day and nighttime using MSG satellite images

    Science.gov (United States)

    Tebbi, Mohsene Abdelfettah; Haddad, Boualem

    2016-09-01

    The aim of this study is to investigate the potential of cloud classification by means of support vector machines using high resolution images from northern Algeria. The images were taken from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board of the Meteosat Second Generation (MSG) satellite. An automatic system was developed to operate during both day and nighttime by following two steps of data processing. The first aims to detect rainy areas in cloud systems, whereas the second delineates convective cells from stratiform ones. A set of 12 spectral parameters was selected to extract information about cloud properties, which are different from day to night. The training and validation steps of this study were performed by in-situ rainfall measurement data, collected during the rainy season of years 2011 and 2012 via automatic rain gauge stations distributed in northern Algeria. Artificial neural networks (ANNs) and support vector machine (SVM) were explored, by combining spectral parameters derived from MSG images. Better performances were obtained by the SVM classifier, in terms of Critical Success Index and Probability of Detection for rainy areas detection (CSI = 0.81, POD = 91%), and also for convective/stratiform delineation (CSI = 0.55, POD = 74%).

  14. Convective Radio Occultations Final Campaign Summary

    Energy Technology Data Exchange (ETDEWEB)

    Biondi, R. [Atmospheric Radiation Measurement, Washington, DC (United States)

    2016-03-01

    Deep convective systems are destructive weather phenomena that annually cause many deaths and injuries as well as much damage, thereby accounting for major economic losses in several countries. The number and intensity of such phenomena have increased over the last decades in some areas of the globe. Damage is mostly caused by strong winds and heavy rain parameters that are strongly connected to the structure of the particular storm. Convection over land is usually stronger and deeper than over the ocean and some convective systems, known as supercells, also develop tornadoes through processes that remain mostly unclear. The intensity forecast and monitoring of convective systems is one of the major challenges for meteorology because in situ measurements during extreme events are too sparse or unreliable and most ongoing satellite missions do not provide suitable time/space coverage.

  15. Thermosolutal convection during dendritic solidification

    Science.gov (United States)

    Heinrich, J. C.; Nandapurkar, P.; Poirier, D. R.; Felicelli, S.

    1989-01-01

    This paper presents a mathematical model for directional solidification of a binary alloy including a dendritic region underlying an all-liquid region. It is assumed initially that there exists a nonconvecting state with planar isotherms and isoconcentrates solidifying at a constant velocity. The stability of this system has been analyzed and nonlinear calculations are performed that show the effect of convection in the solidification process when the system is unstable. Results of calculations for various cases defined by the initial temperature gradient at the dendrite tips and varying strength of the gravitational field are presented for systems involving lead-tin alloys. The results show that the systems are stable for a gravitational constant of 0.0001 g(0) and that convection can be suppressed by appropriate choice of the container's size for higher values of the gravitational constant. It is also concluded that for the lead-tin systems considered, convection in the mushy zone is not significant below the upper 20 percent of the dendritic zone, if al all.

  16. Water column imaging on hydrothermal vent in Central Indian Ridge

    Science.gov (United States)

    Koh, J.; Park, Y.

    2017-12-01

    Water column imaging with Multibeam echosounder systems (MBES) is recently becoming of increasing interest for oceanographic studies. Especially gas bubbles and hot water exposed from hydrothermal vents make acoustic impedance anomalies in cold seawater, water column imaging is very useful for the researchers who want to detect some kinds of hydrothermal activity. We conducted a hydrothermal exploration program, called "INVENT17", using the MBES system, KONGBERG EM122 (12kHz, 1°×1°), mounted on R/V ISABU and we deployed other equipments including video guided hydraulic grab, tow-yo CTD and general CTD with MAPR (Miniature Autonomous Plume Recorder) in 2017. First, to evaluate its capabilities of detection of hydrothermal vent, the surveys using the MBES were conducted at the Solitaire Field, previously identified hydrothermal area of the Central Indian Ridge. The bathymetric data obtained from MBES provided information about detailed morphology of seafloor, but we were not able to achieve the information from the water column imaging data. But the clue of existence of active hydrothermal vent was detected through the values of ΔNTU, dEh/dt, and OPR gained from MAPR, the data means that the hydrothermal activity affects 100m from the seafloor. It could be the reason that we can't find the hydrothermal activity because the range resolution of water column imaging is pretty rough so that the size of 100m-scaled activity has low possibility to distinguish from seafloor. The other reason is there are no sufficient objects to cause strong scattering like as CO2 bubbles or droplets unlike in the mid-Okinawa Trough. And this suggests that can be a important standard to identify properties of hydrothermal vent sites depending on the presence of scattering objects in water mass. To justify this, we should perform more chemical analysis of hot water emanating from hydrothermal vent and collected several bottles of water sample to do that.

  17. The Wall-Rock Record of Incremental Emplacement in the Little Cottonwood-Alta Magmatic and Hydrothermal System, Wasatch Mountains, Utah, U.S.A.

    Science.gov (United States)

    Stearns, M.; Callis, S.; Beno, C.; Bowman, J. R.; Bartley, J. M.

    2017-12-01

    data suggest that the Little Cottonwood aureole developed over several million years and overlapped in time with hydrothermal (re)crystallization of titanite within the Alta Stock. Both systems continued to develop after monazite (re)crystallization within Ophir Shale, which was concurrent with emplacement of the Alta Stock.

  18. Thickness distributions and evolution of growth mechanisms of NH4-illite from the fossil hydrothermal system of Harghita Bai, Eastern Carpathians, Romania

    Science.gov (United States)

    Bobos, Iuliu; Eberl, Dennis D.

    2013-01-01

    The crystal growth of NH4-illite (NH4-I) from the hydrothermal system of Harghita Bãi (Eastern Carpathians) was deduced from the shapes of crystal thickness distributions (CTDs). The 4-illite-smectite (I-S) interstratified structures (R1, R2, and R3-type ordering) with a variable smectite-layer content. The NH4-I-S (40–5% S) structures were identified underground in a hydrothermal breccia structure, whereas the K-I/NH4-I mixtures were found at the deepest level sampled (−110 m). The percentage of smectite interlayers generally decreases with increasing depth in the deposit. This decrease in smectite content is related to the increase in degree of fracturing in the breccia structure and corresponds to a general increase in mean illite crystal thickness. In order to determine the thickness distributions of NH4-I crystals (fundamental illite particles) which make up the NH4-I-S interstratified structures and the NH4,-I/K-I mixtures, 27 samples were saturated with Li+ and aqueous solutions of PVP-10 to remove swelling and then were analyzed by X-ray diffraction. The profiles for the mean crystallite thickness (Tmean) and crystallite thickness distribution (CTD) of NH4-I crystallites were determined by the Bertaut-Warren-Averbach method using the MudMaster computer code. The Tmean of NH4-I from NH4-I-S samples ranges from 3.4 to 7.8 nm. The Tmean measured for the NH4-I/K-I mixture phase ranges from 7.8 nm to 11.7 nm (NH4-I) and from 12.1 to 24.7 nm (K-I).The CTD shapes of NH4-I fundamental particles are asymptotic and lognormal, whereas illites from NH4-I/K-I mixtures have bimodal shapes related to the presence of two lognormal-like CTDs corresponding to NH4-I and K-I.The crystal-growth mechanism for NH4-I samples was simulated using the Galoper code. Reaction pathways for NH4-I crystal nucleation and growth could be determined for each sample by plotting their CTD parameters on an α–β2 diagram constructed using Galoper. This analysis shows that NH4-I crystals

  19. Quantitative impact of hydrothermal alteration on electrical resistivity in geothermal systems from a joint analysis of laboratory measurements and borehole data in Krafla area, N-E Iceland

    Science.gov (United States)

    Lévy, Léa; Páll Hersir, Gylfi; Flóvenz, Ólafur; Gibert, Benoit; Pézard, Philippe; Sigmundsson, Freysteinn; Briole, Pierre

    2016-04-01

    Rock permeability and fluid temperature are the two most decisive factors for a successful geothermal drilling. While those parameters are only measured from drilling, they might be estimated on the basis of their impact on electrical resistivity that might be imaged from surface soundings, for example through TEM (Transient Electro Magnetic) down to one km depth. The electrical conductivity of reservoir rocks is the sum of a volume term depending on fluid parameters and a surface term related to rock alteration. Understanding the link between electrical resistivity and geothermal key parameters requires the knowledge of hydrothermal alteration and its petrophysical signature with the Cation Exchange Capacity (CEC). Fluid-rock interactions related to hydrothermal circulation trigger the precipitation of alteration minerals, which are both witnesses of the temperature at the time of reaction and new paths for the electrical current. Alteration minerals include zeolites, smectites, chlorites, epidotes and amphiboles among which low temperatures parageneses are often the most conductive. The CEC of these mineral phases contributes to account for surface conductivity occuring at the water-rock interface. In cooling geothermal systems, these minerals constitute in petrophysical terms and from surface electrical conduction a memory of the equilibrium phase revealed from electrical probing at all scales. The qualitative impact of alteration minerals on resistivity structure has been studied over the years in the Icelandic geothermal context. In this work, the CEC impact on pore surfaces electrical conductivity is studied quantitatively at the borehole scale, where several types of volcanic rocks are mixed together, with various degrees of alteration and porosity. Five boreholes located within a few km at the Krafla volcano, Northeast Iceland, constitute the basis for this study. The deepest and reference hole, KJ-18, provides cuttings of rock and logging data down to 2215

  20. Observing Convective Aggregation

    Science.gov (United States)

    Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

    2017-11-01

    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  1. Post-drilling changes in seabed landscape and megabenthos in a deep-sea hydrothermal system, the Iheya North field, Okinawa Trough.

    Science.gov (United States)

    Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

    2015-01-01

    There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, 'artificially' creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has

  2. Impact of Assimilation of Conventional and Satellite Radiance GTS Observations on Simulation of Mesoscale Convective System Over Southeast India Using WRF-3DVar

    Science.gov (United States)

    Madhulatha, A.; Rajeevan, M.; Bhowmik, S. K. Roy; Das, A. K.

    2018-01-01

    The primary goal of present study is to investigate the impact of assimilation of conventional and satellite radiance observations in simulating the mesoscale convective system (MCS) formed over south east India. An assimilation methodology based on Weather Research and Forecasting model three dimensional variational data assimilation is considered. Few numerical experiments are carried out to examine the individual and combined impact of conventional and non-conventional (satellite radiance) observations. After the successful inclusion of additional observations, strong analysis increments of temperature and moisture fields are noticed and contributed to significant improvement in model's initial fields. The resulting model simulations are able to successfully reproduce the prominent synoptic features responsible for the initiation of MCS. Among all the experiments, the final experiment in which both conventional and satellite radiance observations assimilated has showed considerable impact on the prediction of MCS. The location, genesis, intensity, propagation and development of rain bands associated with the MCS are simulated reasonably well. The biases of simulated temperature, moisture and wind fields at surface and different pressure levels are reduced. Thermodynamic, dynamic and vertical structure of convective cells associated with the passage of MCS are well captured. Spatial distribution of rainfall is fairly reproduced and comparable to TRMM observations. It is demonstrated that incorporation of conventional and satellite radiance observations improved the local and synoptic representation of temperature, moisture fields from surface to different levels of atmosphere. This study highlights the importance of assimilation of conventional and satellite radiances in improving the models initial conditions and simulation of MCS.

  3. Free convective heat transfer with hall effects, heat absorption and chemical reaction over an accelerated moving plate in a rotating system

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, S.M., E-mail: hussain.modassir@yahoo.com [Department of Mathematics, OP Jindal University, Raigarh 496109 (India); Jain, J., E-mail: jj.28481@gmail.com [Department of Mathematics, OP Jindal University, Raigarh 496109 (India); Seth, G.S., E-mail: gsseth_ism@yahoo.com [Department of Applied Mathematics, Indian School of Mines, Dhanbad 826004 (India); Rashidi, M.M., E-mail: mm_rashidi@yahoo.com [Shanghai Key Lab of Vehicle Aerodynamics and Vehicle Thermal Management System, Tongji University, Shanghai 201804 (China)

    2017-01-15

    The unsteady MHD free convective heat and mass transfer flow of an electrically conducting, viscous and incompressible fluid over an accelerated moving vertical plate in the presence of heat absorption and chemical reaction with ramped temperature and ramped surface concentration through a porous medium in a rotating system is studied, taking Hall effects into account. The governing equations are solved analytically with the help of Laplace transform technique. The unified closed-form expressions are obtained for fluid velocity, fluid temperature, species concentration, skin friction, Nusselt number and Sherwood numbers. The effects of various parameters on fluid velocity, fluid temperature and species concentration are discussed by graphs whereas numerical values of skin friction, Nusselt and Sherwood numbers are presented in tabular form for different values of pertinent flow parameters. The numerical results are also compared with free convective flow near ramped temperature plate with ramped surface concentration with the corresponding flow near isothermal plate with uniform surface concentration. - Highlights: • Magnetic field, Hall current, rotation and chemical reaction play vital role on flow field. • Hall current tends to accelerate secondary fluid velocity in the boundary layer region. • Rotation tends to retard primary fluid velocity throughout the boundary layer region. • Rotation and chemical reaction tend to enhance primary skin friction. • Solutal buoyancy force and permeability of medium reduce primary skin friction.

  4. Modeling convection-diffusion-reaction systems for microfluidic molecular communications with surface-based receivers in Internet of Bio-Nano Things.

    Directory of Open Access Journals (Sweden)

    Murat Kuscu

    Full Text Available We consider a microfluidic molecular communication (MC system, where the concentration-encoded molecular messages are transported via fluid flow-induced convection and diffusion, and detected by a surface-based MC receiver with ligand receptors placed at the bottom of the microfluidic channel. The overall system is a convection-diffusion-reaction system that can only be solved by numerical methods, e.g., finite element analysis (FEA. However, analytical models are key for the information and communication technology (ICT, as they enable an optimisation framework to develop advanced communication techniques, such as optimum detection methods and reliable transmission schemes. In this direction, we develop an analytical model to approximate the expected time course of bound receptor concentration, i.e., the received signal used to decode the transmitted messages. The model obviates the need for computationally expensive numerical methods by capturing the nonlinearities caused by laminar flow resulting in parabolic velocity profile, and finite number of ligand receptors leading to receiver saturation. The model also captures the effects of reactive surface depletion layer resulting from the mass transport limitations and moving reaction boundary originated from the passage of finite-duration molecular concentration pulse over the receiver surface. Based on the proposed model, we derive closed form analytical expressions that approximate the received pulse width, pulse delay and pulse amplitude, which can be used to optimize the system from an ICT perspective. We evaluate the accuracy of the proposed model by comparing model-based analytical results to the numerical results obtained by solving the exact system model with COMSOL Multiphysics.

  5. Modeling convection-diffusion-reaction systems for microfluidic molecular communications with surface-based receivers in Internet of Bio-Nano Things.

    Science.gov (United States)

    Kuscu, Murat; Akan, Ozgur B

    2018-01-01

    We consider a microfluidic molecular communication (MC) system, where the concentration-encoded molecular messages are transported via fluid flow-induced convection and diffusion, and detected by a surface-based MC receiver with ligand receptors placed at the bottom of the microfluidic channel. The overall system is a convection-diffusion-reaction system that can only be solved by numerical methods, e.g., finite element analysis (FEA). However, analytical models are key for the information and communication technology (ICT), as they enable an optimisation framework to develop advanced communication techniques, such as optimum detection methods and reliable transmission schemes. In this direction, we develop an analytical model to approximate the expected time course of bound receptor concentration, i.e., the received signal used to decode the transmitted messages. The model obviates the need for computationally expensive numerical methods by capturing the nonlinearities caused by laminar flow resulting in parabolic velocity profile, and finite number of ligand receptors leading to receiver saturation. The model also captures the effects of reactive surface depletion layer resulting from the mass transport limitations and moving reaction boundary originated from the passage of finite-duration molecular concentration pulse over the receiver surface. Based on the proposed model, we derive closed form analytical expressions that approximate the received pulse width, pulse delay and pulse amplitude, which can be used to optimize the system from an ICT perspective. We evaluate the accuracy of the proposed model by comparing model-based analytical results to the numerical results obtained by solving the exact system model with COMSOL Multiphysics.

  6. A continuous and prognostic convection scheme based on buoyancy, PCMT

    Science.gov (United States)

    Guérémy, Jean-François; Piriou, Jean-Marcel

    2016-04-01

    A new and consistent convection scheme (PCMT: Prognostic Condensates Microphysics and Transport), providing a continuous and prognostic treatment of this atmospheric process, is described. The main concept ensuring the consistency of the whole system is the buoyancy, key element of any vertical motion. The buoyancy constitutes the forcing term of the convective vertical velocity, which is then used to define the triggering condition, the mass flux, and the rates of entrainment-detrainment. The buoyancy is also used in its vertically integrated form (CAPE) to determine the closure condition. The continuous treatment of convection, from dry thermals to deep precipitating convection, is achieved with the help of a continuous formulation of the entrainment-detrainment rates (depending on the convective vertical velocity) and of the CAPE relaxation time (depending on the convective over-turning time). The convective tendencies are directly expressed in terms of condensation and transport. Finally, the convective vertical velocity and condensates are fully prognostic, the latter being treated using the same microphysics scheme as for the resolved condensates but considering the convective environment. A Single Column Model (SCM) validation of this scheme is shown, allowing detailed comparisons with observed and explicitly simulated data. Four cases covering the convective spectrum are considered: over ocean, sensitivity to environmental moisture (S. Derbyshire) non precipitating shallow convection to deep precipitating convection, trade wind shallow convection (BOMEX) and strato-cumulus (FIRE), together with an entire continental diurnal cycle of convection (ARM). The emphasis is put on the characteristics of the scheme which enable a continuous treatment of convection. Then, a 3D LAM validation is presented considering an AMMA case with both observations and a CRM simulation using the same initial and lateral conditions as for the parameterized one. Finally, global

  7. Load frequency control of three area interconnected hydro-thermal ...

    African Journals Online (AJOL)

    user

    hydrothermal reheat power system by the use of Artificial Intelligent and PI Controller. ... form of Kinetic Energy stored in generator prime mover set, which results the ... A control strategy is needed that not only maintains constancy of frequency ...

  8. Evidence for degassing of fresh magma during the 2004-2008 eruption of Mount St. Helens: Subtle signals from the hydrothermal system

    Science.gov (United States)

    Bergfeld, Deborah; Evans, William C.; Spicer, Kurt R.; Hunt, Andrew G.; Kelly, Peter

    2017-01-01

    Results from chemical and isotopic analyses of water and gas collected between 2002 and 2016 from sites on and around Mount St. Helens are used to assess magmatic degassing related to the 2004-2008 eruption. During 2005 the chemistry of hot springs in The Breach of Mount St. Helens showed no obvious response to the eruption, and over the next few years, changes were subtle, giving only slight indications of perturbations in the system. By 2010 however, water chemistry, temperatures, and isotope compositions (δD and δ18O) clearly indicated some inputs of volatiles and heat associated with the eruption, but the changes were such that they could be attributed to a pre-existing, gas depleted magma. An increase of ~ 1.5‰ in the δ13C values of dissolved carbon in the springs was noted in 2006 and continued through 2009, a change that was mirrored by a similar shift in δ13C-CO2 in bubble gas emissions. These changes require input of a new source of carbon to the hydrothermal system and provide clear evidence of CO2 from an undegassed body of magma. Rising trends in 3He/4He ratios in gas also accompanied the increases in δ13C. Since 2011 maximum RC/RA values are ≥ 6.4 and are distinctly higher than 5 samples collected between 1986 and 2002, and provide additional evidence for some involvement of new magma as early as 2006, and possibly earlier, given the unknown time needed for CO2 and He to traverse the system and arrive at the springs.

  9. 3D CFD simulations to study the effect of inclination of condenser tube on natural convection and thermal stratification in a passive decay heat removal system

    Energy Technology Data Exchange (ETDEWEB)

    Minocha, Nitin [Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094 (India); Joshi, Jyeshtharaj B., E-mail: jbjoshi@gmail.com [Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094 (India); Department of Chemical Engineering, Institute of Chemical Technology, Matunga, Mumbai 400 019 (India); Nayak, Arun K. [Reactor Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Vijayan, Pallippattu K., E-mail: vijayanp@barc.gov.in [Reactor Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)

    2016-08-15

    Highlights: • Investigation of three-dimensional natural convection and thermal stratification inside large water pool. • Effect of inclination (α) of condenser tube on fluid flow and heat transfer. • The heat transfer was found to be maximum for α = 90° and minimum for α = 15°. • Laminar-turbulent natural convection and heat transfer in the presence of longitudinal vortices. - Abstract: Many advanced nuclear reactors adopt methodologies of passive safety systems based on natural forces such as gravity. In one of such system, the decay heat generated from a reactor is removed by isolation condenser (ICs) submerged in a large water pool called the Gravity Driven Water Pool (GDWP). The objective of the present study was to design an IC for the passive decay heat removal system (PDHRS) for advanced nuclear reactor. First, the effect of inclination of IC tube on three dimensional temperature and flow fields was investigated inside a pilot scale (10 L) GDWP. Further, the knowledge of these fields has been used for the quantification of heat transfer and thermal stratification phenomenon. In a next step, the knowledge gained from the pilot scale GDWP has been extended to design an IC for real size GDWP (∼10,000 m{sup 3}). Single phase CFD simulation using open source CFD code [OpenFOAM-2.2] was performed for different tube inclination angles (α) (w.r.t. to vertical direction) in the range 0° ⩽ α ⩽ 90°. The results indicate that the heat transfer coefficient increases with increase in tube inclination angle. The heat transfer was found to be maximum for α = 90° and minimum for α = 15°. This behavior is due to the interaction between the primary flow (due to pressure gradient) and secondary flow (due to buoyancy force). The primary flow enhanced the fluid sliding motion at the tube top whereas the secondary flow resulted in enhancement in fluid motion along the circumference of tube. As the angle of inclination (α) of the tube was increased, the

  10. Hydrothermal Cold Sintering

    Science.gov (United States)

    Kang, Xiaoyu

    C, respectively. Process variables were defined and effects of individual parameters were studied systematically through control variable method with Li2MoO4-water system. Crystalline structure, fractured surface morphology and chemical bonding information of the cold sintered pellets were studied with X-ray diffraction (XRD), field effect scanning electron microscopy (FE-SEM) and Raman spectroscopy, etc. Densification mechanism studies were conducted on ZnO. Through comparison experiments, it was found that the Zn2+ concentration in the solution is critical for densification, while dissolution of grains only serves as a means to the former. Through pressure dependent studies, a critical value was found, which correlated well with the hydrostatic pressure keeping liquid water from thermal expansion. These results confirmed establishment of hydrothermal condition that would be important for mass transport in densification. Densification rate variations with process time was estimated and similar time dependence to Kingery's model was found. The densification process was proposed to be consist of three consecutive stages, which are quick initial compaction, grain rearrangement and dissolution-reprecipitation events. Binary metal oxides with different acidities were subjected to cold sintering with various aqueous solutions in establishing a criteria for material selection. It was found that in general materials with high solubility at around neutral pH, high dissolution kinetics and similar free energy to their hydroxides or hydrates at ambient would be more likely for full densification with high phase purity. The anions in solution should also be wisely selected to avoid stable compound or complex formation. To extend the applicable material list for full densification, non-aqueous solvent of dimethyl sulfoxide (DMSO) based solution was studied for cold sintering. Both improvement of pellet density and suppression of hydroxide formation were achieved for MnO by using DMSO

  11. Convective heat transfer

    CERN Document Server

    Kakac, Sadik; Pramuanjaroenkij, Anchasa

    2014-01-01

    Intended for readers who have taken a basic heat transfer course and have a basic knowledge of thermodynamics, heat transfer, fluid mechanics, and differential equations, Convective Heat Transfer, Third Edition provides an overview of phenomenological convective heat transfer. This book combines applications of engineering with the basic concepts of convection. It offers a clear and balanced presentation of essential topics using both traditional and numerical methods. The text addresses emerging science and technology matters, and highlights biomedical applications and energy technologies. What’s New in the Third Edition: Includes updated chapters and two new chapters on heat transfer in microchannels and heat transfer with nanofluids Expands problem sets and introduces new correlations and solved examples Provides more coverage of numerical/computer methods The third edition details the new research areas of heat transfer in microchannels and the enhancement of convective heat transfer with nanofluids....

  12. Comment on “Short-term combined economic emission scheduling of hydrothermal power systems with cascaded reservoirs using differential evolution” by K.K. Mandal and N. Chakaborty [Energy Convers. Manage. 50 (2009) 97–104

    International Nuclear Information System (INIS)

    Ahmadi, Abdollah; Nezhad, Ali Esmaeel

    2015-01-01

    This paper discusses the short-term combined economic emission scheduling of hydrothermal power systems with cascaded reservoirs [Energy Convers Manage. 50 (2009) 97–104], while differential evolution algorithm has been employed to solve the optimization problem. However, this problem is subjected to several constraints like the generation limitations of generating units. The solutions reported in the original paper do not satisfy the constraint on the initial and final reservoir storage volumes of hydro units as well as the constraint on the generated power by such units, which should be positive at any time of the scheduling period. Thus, this paper intends to prove this issue and solve the problem using Normal Boundary Intersection (NBI) method, in order to propose the correct solutions satisfying all the constraints of the short-term hydrothermal scheduling problem

  13. Volcano-hydrothermal energy research at white Island, New Zealand

    International Nuclear Information System (INIS)

    Allis, R.G.

    1994-01-01

    This paper presents the White Island (New Zealand) volcano-hydrothermal research project by the N.Z. DSIR and the Geological Survey of Japan, which is investigating the coupling between magmatic and geothermal systems. The first phase of this investigation is a geophysical survey of the crater floor of the andesite volcano, White Island during 1991/1992, to be followed by drilling from the crater floor into the hydrothermal system. (TEC). 4 figs., 8 refs

  14. Understanding and controlling plasmon-induced convection

    Science.gov (United States)

    Roxworthy, Brian J.; Bhuiya, Abdul M.; Vanka, Surya P.; Toussaint, Kimani C.

    2014-01-01

    The heat generation and fluid convection induced by plasmonic nanostructures is attractive for optofluidic applications. However, previously published theoretical studies predict only nanometre per second fluid velocities that are inadequate for microscale mass transport. Here we show both theoretically and experimentally that an array of plasmonic nanoantennas coupled to an optically absorptive indium-tin-oxide (ITO) substrate can generate >micrometre per second fluid convection. Crucially, the ITO distributes thermal energy created by the nanoantennas generating an order of magnitude increase in convection velocities compared with nanoantennas on a SiO2 base layer. In addition, the plasmonic array alters absorption in the ITO, causing a deviation from Beer-Lambert absorption that results in an optimum ITO thickness for a given system. This work elucidates the role of convection in plasmonic optical trapping and particle assembly, and opens up new avenues for controlling fluid and mass transport on the micro- and nanoscale.

  15. Oxygen isotope study of the Long Valley magma system, California: isotope thermometry and convection in large silicic magma bodies

    Science.gov (United States)

    Bindeman, Ilya; Valley, John

    2002-07-01

    Products of voluminous pyroclastic eruptions with eruptive draw-down of several kilometers provide a snap-shot view of batholith-scale magma chambers, and quench pre-eruptive isotopic fractionations (i.e., temperatures) between minerals. We report analyses of oxygen isotope ratio in individual quartz phenocrysts and concentrates of magnetite, pyroxene, and zircon from individual pumice clasts of ignimbrite and fall units of caldera-forming 0.76 Ma Bishop Tuff (BT), pre-caldera Glass Mountain (2.1-0.78 Ma), and post-caldera rhyolites (0.65-0.04 Ma) to characterize the long-lived, batholith-scale magma chamber beneath Long Valley Caldera in California. Values of δ18O show a subtle 1‰ decrease from the oldest Glass Mountain lavas to the youngest post-caldera rhyolites. Older Glass Mountain lavas exhibit larger ( 1‰) variability of δ18O(quartz). The youngest domes of Glass Mountain are similar to BT in δ18O(quartz) values and reflect convective homogenization during formation of BT magma chamber surrounded by extremely heterogeneous country rocks (ranging from 2 to +29‰). Oxygen isotope thermometry of BT confirms a temperature gradient between "Late" (815 °C) and "Early" (715 °C) BT. The δ18O(quartz) values of "Early" and "Late" BT are +8.33 and 8.21‰, consistent with a constant δ18O(melt)=7.8+/-0.1‰ and 100 °C temperature difference. Zircon-melt saturation equilibria gives a similar temperature range. Values of δ18O(quartz) for different stratigraphic units of BT, and in pumice clasts ranging in pre-eruptive depths from 6 to 11 km (based on melt inclusions), and document vertical and lateral homogeneity of δ18O(melt). Worldwide, five other large-volume rhyolites, Lava Creek, Lower Bandelier, Fish Canyon, Cerro Galan, and Toba, exhibit equal δ18O(melt) values of earlier and later erupted portions in each of the these climactic caldera-forming eruptions. We interpret the large-scale δ18O homogeneity of BT and other large magma chambers as evidence

  16. Mesoscale convective system surface pressure anomalies responsible for meteotsunamis along the U.S. East Coast on June 13th, 2013.

    Science.gov (United States)

    Wertman, Christina A; Yablonsky, Richard M; Shen, Yang; Merrill, John; Kincaid, Christopher R; Pockalny, Robert A

    2014-11-25

    Two destructive high-frequency sea level oscillation events occurred on June 13th, 2013 along the U.S. East Coast. Seafloor processes can be dismissed as the sources, as no concurrent offshore earthquakes or landslides were detected. Here, we present evidence that these tsunami-like events were generated by atmospheric mesoscale convective systems (MCSs) propagating from inland to offshore. The USArray Transportable Array inland and NOAA tide gauges along the coast recorded the pressure anomalies associated with the MCSs. Once offshore, the pressure anomalies generated shallow water waves, which were amplified by the resonance between the water column and atmospheric forcing. Analysis of the tidal data reveals that these waves reflected off the continental shelf break and reached the coast, where bathymetry and coastal geometry contributed to their hazard potential. This study demonstrates that monitoring MCS pressure anomalies in the interior of the U.S. provides important observations for early warnings of MCS-generated tsunamis.

  17. Flash propagation and inferred charge structure relative to radar-observed ice alignment signatures in a small Florida mesoscale convective system

    Science.gov (United States)

    Biggerstaff, Michael I.; Zounes, Zackery; Addison Alford, A.; Carrie, Gordon D.; Pilkey, John T.; Uman, Martin A.; Jordan, Douglas M.

    2017-08-01

    A series of vertical cross sections taken through a small mesoscale convective system observed over Florida by the dual-polarimetric SMART radar were combined with VHF radiation source locations from a lightning mapping array (LMA) to examine the lightning channel propagation paths relative to the radar-observed ice alignment signatures associated with regions of negative specific differential phase (KDP). Additionally, charge layers inferred from analysis of LMA sources were related to the ice alignment signature. It was found that intracloud flashes initiated near the upper zero-KDP boundary surrounding the negative KDP region. The zero-KDP boundary also delineated the propagation path of the lightning channel with the negative leaders following the upper boundary and positive leaders following the lower boundary. Very few LMA sources were found in the negative KDP region. We conclude that rapid dual-polarimetric radar observations can diagnose strong electric fields and may help identify surrounding regions of charge.

  18. Integrated geophysical and hydrothermal models of flank degassing and fluid flow at Masaya Volcano, Nicaragua

    Science.gov (United States)

    Sanford, Ward E.; Pearson, S.C.P.; Kiyosugi, K.; Lehto, H.L.; Saballos, J.A.; Connor, C.B.

    2012-01-01

    We investigate geologic controls on circulation in the shallow hydrothermal system of Masaya volcano, Nicaragua, and their relationship to surface diffuse degassing. On a local scale (~250 m), relatively impermeable normal faults dipping at ~60° control the flowpath of water vapor and other gases in the vadose zone. These shallow normal faults are identified by modeling of a NE-SW trending magnetic anomaly of up to 2300 nT that corresponds to a topographic offset. Elevated SP and CO2 to the NW of the faults and an absence of CO2 to the SE suggest that these faults are barriers to flow. TOUGH2 numerical models of fluid circulation show enhanced flow through the footwalls of the faults, and corresponding increased mass flow and temperature at the surface (diffuse degassing zones). On a larger scale, TOUGH2 modeling suggests that groundwater convection may be occurring in a 3-4 km radial fracture zone transecting the entire flank of the volcano. Hot water rising uniformly into the base of the model at 1 x 10-5 kg/m2s results in convection that focuses heat and fluid and can explain the three distinct diffuse degassing zones distributed along the fracture. Our data and models suggest that the unusually active surface degassing zones at Masaya volcano can result purely from uniform heat and fluid flux at depth that is complicated by groundwater convection and permeability variations in the upper few km. Therefore isolating the effects of subsurface geology is vital when trying to interpret diffuse degassing in light of volcanic activity.

  19. National Alliance for Advance Biofuels and Bio-Products Final Technical Report Addendum Hydrothermal Processing Pilot System

    Energy Technology Data Exchange (ETDEWEB)

    Oyler, James [Genifuel Corporation

    2015-12-22

    The main objective of the NAABB was to combine science, technology, and engineering expertise from across the nation to break down critical technical barriers to commercialization of algae-based biofuels. As a part of the consortium, Genifuel’s NAABB goals was to fabricate and demonstrate a pilot-scale system to convert algae into fuels. The purpose of this pilot system was to show that processes developed in the laboratory at bench-scale during the program could be successfully scaled up to a pre-commercial level, and thereby provide visibility into the ultimate viability and cost of algae biofuels. The pilot system has now been completed and tested, and this report documents what has been achieved.

  20. Ensemble cloud-resolving modelling of a historic back-building mesoscale convective system over Liguria: the San Fruttuoso case of 1915

    Science.gov (United States)

    Parodi, Antonio; Ferraris, Luca; Gallus, William; Maugeri, Maurizio; Molini, Luca; Siccardi, Franco; Boni, Giorgio

    2017-05-01

    Highly localized and persistent back-building mesoscale convective systems represent one of the most dangerous flash-flood-producing storms in the north-western Mediterranean area. Substantial warming of the Mediterranean Sea in recent decades raises concerns over possible increases in frequency or intensity of these types of events as increased atmospheric temperatures generally support increases in water vapour content. However, analyses of the historical record do not provide a univocal answer, but these are likely affected by a lack of detailed observations for older events. In the present study, 20th Century Reanalysis Project initial and boundary condition data in ensemble mode are used to address the feasibility of performing cloud-resolving simulations with 1 km horizontal grid spacing of a historic extreme event that occurred over Liguria: the San Fruttuoso case of 1915. The proposed approach focuses on the ensemble Weather Research and Forecasting (WRF) model runs that show strong convergence over the Ligurian Sea (17 out of 56 members) as these runs are the ones most likely to best simulate the event. It is found that these WRF runs generally do show wind and precipitation fields that are consistent with the occurrence of highly localized and persistent back-building mesoscale convective systems, although precipitation peak amounts are underestimated. Systematic small north-westward position errors with regard to the heaviest rain and strongest convergence areas imply that the reanalysis members may not be adequately representing the amount of cool air over the Po Plain outflowing into the Ligurian Sea through the Apennines gap. Regarding the role of historical data sources, this study shows that in addition to reanalysis products, unconventional data, such as historical meteorological bulletins, newspapers, and even photographs, can be very valuable sources of knowledge in the reconstruction of past extreme events.

  1. Numerical study on turbulent forced convective heat transfer using nanofluids TiO2 in an automotive cooling system

    Directory of Open Access Journals (Sweden)

    Adnan M. Hussein

    2017-03-01

    Full Text Available The limited thermal properties of liquids have led to the addition of solid nanoparticles to liquids in many industrial applications. In this paper, the friction factor and forced convection heat transfer of TiO2 nanoparticles dispersed in water in a car radiator was numerically determined. Four different nanofluid volume concentrations (1%, 2%, 3% and 4% were used, and the resulting thermal properties were evaluated. The Reynolds number and inlet temperature ranged from 10000 to 100000 and from 60 to 90 °C, respectively. The results showed that the friction factor decreases as the Reynolds number increases and increases as the volume concentration increases. Additionally, the Nusselt number increases as the Reynolds number and volume concentration of the nanofluid increases. The TiO2 nanofluid at low concentrations can enhance the heat transfer efficiency up to 20% compared with that of pure water. There was good agreement among the CFD analysis and experimental data available in the literature.

  2. The approximate analytical solution of the internal problem of conductive and laminar free convection

    Directory of Open Access Journals (Sweden)

    M. I. Popov

    2016-01-01

    Full Text Available The approximate analytical solution of a problem about nonstationary free convection in the conductive and laminar mode of the Newtonian liquid in square area at the instantaneous change of temperature of a sidewall and lack of heat fluxes is submitted on top and bottom the bases. The equations of free convection in an approximation of Oberbeka-Bussinesk are linearized due to neglect by convective items. For reduction of number of hydrothermal parameters the system is given to the dimensionless look by introduction of scales for effect and explanatory variables. Transition from classical variables to the variables "whirlwind-a flow function" allowed to reduce system to a nonstationary heat conduction equation and a nonstationary nonuniform biharmonic equation, and the first is not dependent on the second. The decision in the form of a flow function is received by application