Sökning: "Water cycle"

Visar resultat 1 - 5 av 317 avhandlingar innehållade orden Water cycle.

  1. 1. Time-resolved Structural and Mechanistic Studies of Water Oxidation in Photosystem II : water here, water there, water everywhere

    Författare :Casper de Lichtenberg; Johannes Messinger; Wolfgang P. Schröder; Holger Dau; Umeå universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; NATURAL SCIENCES; Oxygenic Photosynthesis; Photosystem II; TR-MIMS; isotope exchange; EPR; EDNMR; water splitting; water oxidation;

    Sammanfattning : Oxygenic photosynthesis is undisputedly one of the most important chemical processes for human life on earth as it not only fills the atmosphere with the oxygen that we need to breathe, but also sustains the accumulation of biomass, which is not only used as nourishment but is also present in almost every aspect of our lives as building material, textiles in clothes and furniture, or even as living decorations to name a few.The photosynthetic water-splitting mechanism is catalyzed by a water:plastoquinone oxido-reductase by the name of photosystem II (PSII), which is embedded in the thylakoid membranes of plants, algae and cyanobacteria. LÄS MER

  2. 2. Global and continental perspectives on the sustainability of future agricultural water management

    Författare :Luigi Piemontese; Fernando Jaramillo; Luigia Brandimarte; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; water; sustainable water management; agriculture; water harvesting; climate change; vetenskap om hållbar utveckling; Sustainability Science;

    Sammanfattning : Ensuring water and food security in the Anthropocene requires an understanding of combined climate change patterns and land and water management options from local to global scale. In many regions, irrigation from river and groundwater sources is being used at unsustainable rates and climate change will further threaten those water sources. LÄS MER

  3. 3. Heat and water flows in freezing and thawing soils : numerical modelling, laboratory and field observations

    Författare :Helén Engelmark; Luleå tekniska universitet; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Vattenteknik; Water Resources Engineering;

    Sammanfattning : A laboratory study of infiltration rates into frozen and unfrozen fine sand, including temperature effects of both soil and infiltration water, is reported. The average infiltration rate varied from about 10.6 mm/min for unfrozen conditions, to about 1-2 mm/min for frozen conditions. LÄS MER

  4. 4. Advanced power cycles with mixture as the working fluid

    Författare :Maria Jonsson; KTH; []
    Nyckelord :power cycle; mixture working fluid; Kalina cycle; ammonia-water mixture; reciprocating internal combustion engine; bottoming cycle; gas turbine; evaporative gas turbine; air-water mixture; exergy;

    Sammanfattning : The world demand for electrical power increasescontinuously, requiring efficient and low-cost methods forpower generation. This thesis investigates two advanced powercycles with mixtures as the working fluid: the Kalina cycle,alternatively called the ammonia-water cycle, and theevaporative gas turbine cycle. LÄS MER

  5. 5. Changes of evapotranspiration and water cycle in China during the past decades

    Författare :Ge Gao; Göteborgs universitet; Göteborgs universitet; Gothenburg University; []
    Nyckelord :Potential evapotranspiration; Actual evapotranspiration; Spatial and temporal characteristic; Trend; Controlling factors; Water cycle; Thornthwaite water balance; China;

    Sammanfattning : Evapotranspiration is the second largest quantity in the water cycle and an important indicator for climate changes. Accurate estimations and better understanding of evapotranspiration are required in hydrologic studies and water resources modelling under stationary and changing climate conditions. LÄS MER