Sökning: "gas evolution rate"

Visar resultat 1 - 5 av 38 avhandlingar innehållade orden gas evolution rate.

  1. 1. Factors Related to the Formation of Gas Porosity in Grey Cast Iron: Investigation of Core Gas Evolution and Gas Concentrations in Molten Iron

    Författare :Jessica Orlenius; [2008]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; core binders; Gas porosity; hydrogen; grey iron; gas absorption; nitrogen; oxygen; gas evolution rate; green sand; mould filling; gas volume; gas solubility;

    Sammanfattning : Since gas porosity is a major casting problem, it is of greatest importance to increase the knowledge about the foundry process in order to minimise the presence of gas porosity and thereby improving the casting quality. Gas porosity is generally considered to originate from gases precipitated during solidification of iron and from entrained gas picked up by the metal during the mould filling. LÄS MER

  2. 2. On the origin and evolution of blue compact galaxies

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Göran A. Östlin; [1998]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; galaxies - compact; formation; evolution; starburst; interactions; dwarf; photometry; kinematics and dynamics; low surface brightness galaxies; Astronomi; NATURAL SCIENCES Physics Astronomy and astrophysics; NATURVETENSKAP Fysik Astronomi och astrofysik; astronomi; Astronomy;

    Sammanfattning : This thesis is focused on the origin and evolution of blue compact galaxies (BCGs). BCGs are low mass galaxies characterised by blue colours, low chemical abundances and high star formation rates. The gas consumtion time scale is considerable shorter than the age of the universe and thus the high star formation rate must be transient. LÄS MER

  3. 3. Studies of Interstellar Molecular Gas in the Magellanic Clouds

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Arto Heikkilä; [1998]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; abundances-Galaxies; evolution; molecules-Galaxies; Magellanic Clouds-Interstellar medium; molecules-Galaxies; interstellar medium-Galaxies;

    Sammanfattning : Results of observational studies of interstellar molecular gas clouds in the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC), two nearby metal-poor and dust-poor dwarf galaxies, are presented. Spectral line radiation emitted by interstellar molecules has been used to probe the physical state and the chemical composition of individual molecular clouds. LÄS MER

  4. 4. On the Winds of Carbon Stars and the Origin of Carbon A Theoretical Study

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Lars Mattsson; Susanne Höfner; Nils Bergvall; Kjell Olofsson; Martin Groenewegen; [2009]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; AGB stars; carbon stars; mass loss; stellar winds; circumstellar matter; cosmic dust; stellar evolution; nucleosynthesis; galactic chemical evolution; NATURAL SCIENCES Physics Astronomy and astrophysics; NATURVETENSKAP Fysik Astronomi och astrofysik; Astronomy; Astronomi; Fysik; Physics;

    Sammanfattning : Carbon is the basis for life, as we know it, but its origin is still largely unclear. Carbon-rich Asymptotic Giant Branch (AGB) stars (carbon stars) play an important rôle in the cosmic matter cycle and may contribute most of the carbon in the Galaxy. LÄS MER

  5. 5. Synthesis of Transition Metal Aluminides from Elemental Powder Mixtures

    Detta är en avhandling från Lund University (Media-Tryck)

    Författare :Hossein Sina; [2015]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aluminides; Intermetallics; Powder Metallurgy; Reactive Sintering; Combustion Synthesis; Thermal Analysis; DSC; Onset temperature; Phase evolution; SEM; EDS; XRD;

    Sammanfattning : Structural components such as those used in gas turbines for energy conversion applications, are subjected to high loads at elevated temperatures. In order to ensure that the components survive under these conditions for a sufficiently long time, it is imperative to select materials with good high temperature properties like strength and corrosion resistance. LÄS MER