Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 772 for “"Hydrothermal"”.
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Diffuse flow from hydrothermal vents
… of a scheme for monitoring the flow from diffuse hydrothermal vents in the ocean. A deployment of an array at the Southern Juan de Fuca Ridge yielded measurements of a variety of diffuse plume properties, including total heat output. Two distinct sources of hydrothermal flow were detected during …
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Hydrothermal carbonization of waste biomass
Hydrothermal carbonization (in acronym, HTC) is a thermochemical conversion process through which it is possible to directly transform wet organic substrates into a carbonaceous material, referred as hydrochar. Hydrochar has chemical and physical characteristics that make it similar to fossil peats …
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Hydrothermal and ionothermal carbon structures
… carbon materials employing the process of hydrothermal carbonisation (HC) is described. In the second part, the synthesis of heteroatom - containing carbon materials for electrochemical and fuel cell applications employing ionic liquid precursors is presented. On base of a thorough review …
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Hydrothermal Carbonisation of Novel Biomasses
… help revolutionise the global energy economy. Hydrothermal Carbonisation (HTC) is a technology wherein biomass exposed to subcritical water at 180 °C – 260 °C is thermochemically converted into an energy-dense “hydrochar” with strong thermal and elemental similarities to fossil coal. However, …
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Larval dispersal between hydrothermal vent habitats
Hydrothermal vents are isolated, short-term habitats that support unique biotic assemblages with relatively high biomass utilizing an unusual energy source. How these communities establish themselves and maintain species identity despite their isolation and impermanence is a significant question in …
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Hydrothermal aging of zeolite-based catalysts
… and alumina-silica gel matrix, was treated hydrothermally under simulated FCC regenerator conditions in a laboratory scale fluidized bed. Fresh and steam-aged catalysts were characterized by surface area reduction using the nitrogen BET and t-Plot surface area methods. The surface morphology …
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Hydrothermal Processes Applied to Sludge Reduction
… new technologies. One of these technologies is HydroThermal Carbonisation (HTC), where sludge is heated up to 180-250 °C at water vapour pressure producing a solid product enriched in carbon for different possible exploitations. The aim of this work is to apply HTC to different kinds of sludge …
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Hydrothermal oxidation of simple organic compounds
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1998.
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Larval dispersal between hydrothermal vent habitats
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 1996.
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Biomass reforming processes in hydrothermal media
While hydrothermal technologies offer distinct advantages in being able to process a wide variety of biomass feedstocks, the composition of the feedstock will have a large effect on the processing employed. This thesis characterizes the role of two major components of biomass, salts and proteins, …
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Upgrading biomass by hydrothermal and chemical conditioning
… thermal pretreatment technologies, known as hydrothermal carbonization and dry torrefaction. In dry torrefaction, also known as torrefaction or mild pyrolysis, dry solid biomass is treated in an inert gas environment in a temperature range of 200-300oC for more than one hour. In hydrothermal …
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The chemistry of iron in hydrothermal plumes
This thesis investigates the role of submarine hydrothermal vents in the global marine Fe<br/>budget. While debate continues over the sources of dissolved Fe to the global deep-ocean<br/>dissolved Fe budget, it had been presumed, until recently, that all the Fe emitted from<br/>hydrothermal vents …
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Hydrothermal plumes and processes in Indian Ocean
The predicted cycling of the whole ocean through hydrothermal plumes is comparable to the mixing time of the oceans (few thousand years). Hence, understanding hydrothermal plume processes is crucial if their impact on the global geochemical cycles of elements is to be assessed. One of the most …
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Hydrothermal processing of biogenic residues in Germany
… which can make their use uneconomical. Hydrothermal processes (HTP) seem to be promising, since they require an aqueous environment for optimal processing anyway. Although technological progress within the industry is recognisable, however, to date HTP have not been established in …
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Organic geochemical biosignatures in alkaline Hydrothermal ecosystems
… lipids from carbonates of the Lost City Hydrothermal Field. This ultramafic ecosystem produces methane highly enriched in 13C relative to most biotic methane. We find that the 13C enrichment in methanogen lipids is even stronger -- demonstrating that the Methanosarcinales in active vents …
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Geophysical Investigation of the Yellowstone Hydrothermal System
… and hot springs), yet little is known about the hydrothermally active zones hundreds of meters beneath the features. Transient electromagnetic (TEM) soundings and 2D direct current (DC) resistivity profiles show that hydrothermal alteration at active sites have a higher electrical conductivity …
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The hydrothermal alteration of oceanic basalts by seawater
… temperatures. The mineralogy and chemistry of hydrothermally altered pillow basalts dredged from the Mid-Atlantic Ridge, and belonging to the greenschist facies, have been studied in order to determine the mineralogical changes that result from hyrdrothennal alteration, and to assess the …
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Characterization of nanostructures ZnO synthesized through hydrothermal method
… be derived using a variety of techniques. Using hydrothermal synthesis, ZnO nanostructures can be produced easily on a large scale due to the low temperature involved. Among the factors that influence the crystallinity of ZnO nanostructures are types of alkaline solution, the alkaline pH value …
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