Search results for " Springs"

showing 10 items of 12 documents

Thermomineral waters of Greece: geochemical characterization

2020

75 °C). In terms of pH most results vary from 5.5 to 823 °C) ii) warm (23 40 °C) iii) thermal (40 75 °C) and iv) hyperthermal (&gtfew springs show either very low pH (&lt10) proposing serpentinization processes. Regarding TDS concentrations collected waters can be subdivided into low salinity (up to 1.5 g/L) brackish (up to 20 g/L) and saline (up to 43 g/L). The medium high salinities can be justified by mixing with sea water and/or strong waterrock interaction processes. Isotope composition of O and H ranges from 12.7 to +2.7 ‰ SMOW and from 91 to +12 ‰ SMOW respectively and is generally comprised between the Global Meteoric Water Line and the East Mediterranean Meteoric Water Line. Only few water samples show a positive shift for δ18O possibly related to high temperature waterrock interaction processes. Carbon dioxide (18 997000 μmol/mol) or N2 (1100 989000 μmol/mol) or CH4 (&ltMany geothermal areas of Greece are located in regions affected by Miocene or Quaternary volcanism and in continental basins characterised by elevated heat flow. Moreover the majority of them is found along the coast as well as in islands of the Aegean Sea and thus thermal water is often brackish to saline due to marine intrusion into costal aquifer. In the present study almost 300 thermal and cold mineral water samples were collected along the Hellenic territory with their physicochemical parameters (temperature pH electrical conductivity and Eh) and the amount of bicarbonates (titration with 0.1N HCl) being determined in situ. Additionally gases found either in free or dissolved phase were sampled. Both water and gas samples were analysed at the INGVPa laboratories for major ions (Ion Chromatography) silica (Inductively Coupled Plasma Optical Emission Spectrometry) chemical composition of free and dissolved gases (Gas Chromatography) water isotopes (O and H) and carbon and helium isotopes of free and dissolved gases (Mass Spectrometry). The temperature of the investigated waters ranges from 6.5 to 98°C pH from 1.96 to 11.98 whilst Total Dissolved Solids (TDS) from 0.06 to 43 g/L. Based on the temperature parameter waters can be divided into four groups: i) cold (&lt0.5 913000 μmol/mol) are the prevailing gas species found in the studied sites. The δ13CCO2 values ranged from 20.1 to +8.5 ‰ whilst the isotope ratio of He from 0.21 to 6.71 R/RA.4) suggesting interaction with H2Srich gases or very high pH values (&gtSettore GEO/08 - Geochimica E Vulcanologia
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Poggetti Vecchi (Tuscany, Italy): A late Middle Pleistocene case of human-elephant interaction

2019

Abstract A paleosurface with a concentration of wooden-, bone-, and stone-tools interspersed among an accumulation of fossil bones, largely belonging to the straight-tusked elephant Palaeoloxodon antiquus, was found at the bottom of a pool, fed by hot springs, that was excavated at Poggetti Vecchi, near Grosseto (Tuscany, Italy). The site is radiometrically dated to the late Middle Pleistocene, around 171,000 years BP. Notable is the association of the artifacts with the elephant bones, and in particular the presence of digging sticks made from boxwood (Buxus sp.). Although stone tools show evidence of use mainly on animal tissues, indicating some form of interaction between hominins and an…

Buxus010506 paleontologyFood ChainTaphonomyPleistoceneElephantsFossil bone01 natural sciencesNatural (archaeology)Vertebrate taphonomy Lithic and wooden artifacts Early Neanderthals Thermal water springs Central ItalyAnimals0601 history and archaeologyEcology Evolution Behavior and SystematicsNeanderthals0105 earth and related environmental sciences060101 anthropologyTool Use BehaviorbiologyPalaeoloxodonFossilsPaleontology06 humanities and the artsSettore GEO/01 - Paleontologia E Paleoecologiabiology.organism_classificationArchaeologyDiggingGeographyArchaeologyItalyAnthropology
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Evaluation of the power quality from a seawave power farm for different interconnection schemes

2007

In this paper we present an approach to the interconnection of a seawave power farm to the grid The generator type used in the farm is a Permanent Magnet (PM) linear generator driven from the seawaves that generates, therefore, highly distorted emfs. We propose and compare two possible ways to interconnect the farm to the grid. One is based on an approach where for each generator there is a conversion subsystem that permits the direct connection of each generator to the a.c. network, the other one is based on an ac.-d.c. converter that is connected to the generator, the converter is connected to a dc link that can receive the power from every unit and that can supply a dc-ac converter direc…

InterconnectionEngineeringGenerator (computer programming)business.industryElectrical engineeringSettore ING-IND/32 - Convertitori Macchine E Azionamenti ElettriciGridPower (physics)Power quality Power generation DC generators Distributed power generation Stator windings Mesh generation Permanent magnets Stochastic processes Frequency SpringsElectricity generationMesh generationLinear congruential generatorElectronic engineeringbusinessSynchronous motor
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Static output-feedback controller design for vehicle suspensions: an effective two-step computational approach

2014

In this study, a novel two-step methodology is applied in designing static output-feedback controllers for a class of vehicle suspension systems. Following this approach, an effective synthesis of static output-feedback controllers can be carried out by solving two consecutive linear matrix inequality optimisation problems. To illustrate the main features of the proposed design strategy, two different static output-feedback H 8 controllers are designed for a quarter-car suspension system. The first of those controllers uses the suspension deflection and the sprung mass velocity as feedback information, whereas the second one only requires the sprung mass velocity to compute the control acti…

Output feedbackEngineeringFrequency responseControl and Optimization:Informàtica::Automàtica i control [Àrees temàtiques de la UPC]Linear matrix inequalitiesVehicle suspensionsDesign strategyControl and Systems Engineering; Human-Computer Interaction; Computer Science Applications1707 Computer Vision and Pattern Recognition; Control and Optimization; Electrical and Electronic EngineeringFeedback control systemsMatrius (Matemàtica)Vehicles -- Ressorts i suspensió:93 Systems Theory; Control [Classificació AMS]Control theoryDeflection (engineering)ControlElectrical and Electronic EngineeringMatrix inequalitiesSuspension (vehicle)Controller design:93 Systems Theory [Classificació AMS]Vehicles--Springs and suspensionbusiness.industryLinear matrix inequality:Matemàtiques i estadística [Àrees temàtiques de la UPC]Control engineeringComputer Science Applications1707 Computer Vision and Pattern RecognitionVehicles -- Springs and suspensionComputer Science ApplicationsHuman-Computer InteractionControl and Systems EngineeringSistemes de control per retroaccióSprung massbusinessStatic output-feedback control
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Coseismic geochemical variations in some gas emissions of Umbria region (Central Italy)

2000

Abstract Coseismic geochemical variations have been detected in some gaseous vents and natural springs during the last seismic crisis occurred in Umbria region (Central Apennines), that started on September 26th, 1997 with several moderate earthquakes (up to M1 5.8). The results of chemical analyses performed on both gas and water samples taken at a weekly rate, combined with analyses on continuous gas flow rate nearby San Faustino site, suggest that the variations can be interpreted as possible consequence of the crustal permeability changes induced by earthquake shaking.

Permeability (earth sciences)General Earth and Planetary SciencesNatural SpringsGas emissionsGeomorphologyGeologyPhysics and Chemistry of the Earth, Part A: Solid Earth and Geodesy
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New, Rare and Constant Habitats for Endangered Aquatic Plant Communities: The Importance of Microhabitats for Global biodiversity

2019

Natural water reservoirs are very valuable floristic sites, with springs particularly important for the preservation of floral biodiversity. This paper presents, as a case study, a community of water plants that is new to limnocrene karst springs in Europe: Potametum alpini (Potametea), found in Poland. The paper provides the floristic composition and ecological requirements of this plant association, which is rare and endangered in Europe. According to our knowledge, the habitat data presented here are unique as they are published for the first time for this plant community, and thus it is currently not possible to compare them with data from other authors. Our study confirms the importanc…

Range (biology)BiodiversityEndangered species01 natural sciencesglobal biodiversity; karst springs; microhabitats; rare habitats; rare plant communities03 medical and health sciencesAquatic plant010503 geologylcsh:QH301-705.50105 earth and related environmental sciencesNature and Landscape Conservation0303 health sciencesmicrohabitatsEcologyEcologyEcological Modeling030302 biochemistry & molecular biologykarst springsrare plant communitiesPlant communityAgricultural and Biological Sciences (miscellaneous)Water resourcesGeographyHabitatlcsh:Biology (General)rare habitatsglobal biodiversityGlobal biodiversityDiversity
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I thermà loutrà di Termini Imerese dalla presenza mitica di Eracle alle terme romane

2019

Le sorgenti calde di Termini Imerese sono legate nel mito raccontato da Diodoro alla presenza di Eracle fin dall'età arcaica. La popolarità dell'eroe nell'isola è confermata dall'evidenza archeologica non solo nella colonia greca di Himera, ma anche nel suo territorio. E' probabile che un edificio termale esistesse nell'area prima dell'età romana, ma è solo dopo la deduzione di una colonia romana a Thermae in età augustea che venne costruito un edificio monumentale riccamente decorato, messo parzialmente in luce da recenti scavi. The thermal springs of Termini Imerese are linked in myth to the presence of Herakles from the Archaic period. The relationship between the tale told by Diodoros o…

Settore L-ANT/09 - Topografia AnticaSettore L-ANT/07 - Archeologia ClassicaThermà loutrà Termini Imerese Ancient hot SpringsThermà loutrà Termini Imerese Sorgenti termali
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Regional variations in the chemical and helium–carbon isotope composition of geothermal fluids across Tunisia

2011

Abstract Tunisia has numerous thermo-mineral springs. Previous studies have shown that their chemical composition and occurrence are strongly influenced by the regional geology. However little work has been done so far to study the isotopic composition of volatiles associated with these geothermal manifestations. Here, we report on the results of an extensive survey of both natural hot springs and production wells across Tunisia, aimed at investigating the spatial distribution of thermal fluids' geochemical characteristics and He–C isotopic composition. The chemistry of the analyzed samples highlights the heterogeneity of the water mineralization processes in Tunisia, as a consequence of th…

Tunisia010504 meteorology & atmospheric sciencesEarth scienceGeochemistryAquiferengineering.material010502 geochemistry & geophysics01 natural sciencesMantle (geology)Geochemistry and PetrologyTunisia; Helium isotopes; Carbon isotopes; Geothermal fluids; Groundwaters; Thermal springs[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environmentGroundwaterChemical compositionGeothermal gradientComputingMilieux_MISCELLANEOUS0105 earth and related environmental sciences[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmospheregeographygeography.geographical_feature_categoryRiftCarbon isotopeThermal springsGeologyHelium isotopeSettore GEO/08 - Geochimica E Vulcanologia13. Climate actionIsotopes of carbonMagmatismengineeringHaliteGeothermal fluidGeologyChemical Geology
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Importance of dispersal and thermal environment for mycorrhizal communities: lessons from Yellowstone National Park

2011

International audience; The relative importance of dispersal and niche restrictions remains a controversial topic in community ecology, especially for microorganisms that are often assumed to be ubiquitous. We investigated the impact of these factors for the community assembly of the root-symbiont arbuscular mycorrhizal fungi (AMF) by sampling roots from geothermal and nonthermal grasslands in Yellowstone National Park (YNP), followed by sequencing and RFLP of AMF ribosomal DNA. With the exception of an apparent generalist RFLP type closely related to Glomus intraradices, a distance-based redundancy analysis indicated that the AMF community composition correlated with soil pH or pH-driven c…

Wyoming0106 biological sciencesMetacommunitycharacteristicshabitatYellowstone National Parkparc national de YellowstoneBiologyPoaceaecomplex mixtures010603 evolutionary biology01 natural sciencesHot Springstype de solsoilrestriction fragment length polymorphismsMycorrhizaeSoil pHBotanyAnimalsEcosystemSoil MicrobiologyEcology Evolution Behavior and Systematicsarbuscular mycorrhizal fungi community composition dispersal2. Zero hungerEcological nicheBisonCommunitypHEcologyfungiCommunity structuretemperaturefood and beveragesPlant communityHydrogen-Ion Concentration15. Life on landnicheBiological dispersalRFLP[SDE.BE]Environmental Sciences/Biodiversity and EcologySoil microbiologyPolymorphism Restriction Fragment Length010606 plant biology & botanyEcology
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Multiple origins of methane in fluids circulating in the Othrys ophiolite, central Greece

2018

The complex geology of Greece includes two important parallel running ophiolitic belts. The Othrys Massif in central Greece belongs to westernmost of them. In and around this wide ophiolite outcrop, some cold hyperalkaline and some hypothermal (T < 40°C) alkaline springs are present. Thirty water samples were collected at 17 different sites and both bubbling and dissolved gases were analysed for their chemical (He, Ne, H2, O2, N2, CH4, C2H6, CO2 and H2S) and isotope (He, δ13C-CO2, δ 13C-CH4, δ 2H-CH4) composition. All samples except one have H2S contents below detection limit (10 μmol/mol), whilst H2 (from <2 to 2500 μmol/mol), CO2 (up to 26,000 but generally below 1000 μmol/mol) and …

continental serpentinization hyperalkaline springs bubbling and dissolved gasesSettore GEO/08 - Geochimica E Vulcanologia
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