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Visar resultat 1 - 5 av 68 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Resistance and recolonization of bryophyte assemblages following disturbances : - detecting patterns and exploring mechanisms

    Författare :Martin Schmalholz; Kristoffer Hylander; Jari Kouki; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Bryophytes; boreal forest; boulders; clear-cutting; disturbance; establishment; insect outbreaks; microtopography; recolonization; resistance; spatial heterogeneity; succession; wildfires; Biology; Biologi; Plant Ecology; växtekologi;

    Sammanfattning : Disturbances are ubiquitous features of most northern forest ecosystems. The subsequent response of plant assemblages on both short (resistance or not) and long term (recolonization or not) will depend on a number of factors operating at several spatial scales. LÄS MER

  3. 2. Tribology at the Cutting Edge : A Study of Material Transfer and Damage Mechanisms in Metal Cutting

    Författare :Julia Lundberg Gerth; Urban Wiklund; Uppsala universitet; []
    Nyckelord :Tribology; Metal cutting; Gear hobbing; Wear; Coating; Residual stress; Material transfer; Steel; Teknisk fysik med inriktning mot tribomaterial; Engineering Science with specialization in Tribo Materials;

    Sammanfattning : The vision of this thesis is to improve the metal cutting process, with emphasis on the cutting tool, to enable stable and economical industrial production while using expensive tools such as hobs. The aim is to increase the tribological understanding of the mechanisms operating at a cutting edge and of how these can be controlled using different tool parameters. LÄS MER

  4. 3. On wear of wood-cutting tools : Tool materials, wear mechanisms and modelling

    Författare :Johan Nordström; []
    Nyckelord :Tool material; Wood cutting; Wear; Modelling;

    Sammanfattning : Bandsaw blades are commonly used in the sawmill industry for timber cutting. The saw teeth are gradually worn during cutting and will finally cause unacceptable surface roughness and dimensional deviations on the sawn wood product. Maintenance by re-sharpening of the saw teeth is therefore necessary after a certain time of sawing. LÄS MER

  5. 4. Positional Accuracy of Drilled Holes

    Författare :Jacek K Kaminski; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; corresponding cutting forces; chip areas; workpiece material; drill wandering; rigidity; drill length; hole-making; surface slope; hole positional accuracy; drilling; conventional point geometry; high-speed steel twist drills; cutting resistance;

    Sammanfattning : When selecting hole-making sequences, the positional accuracy mainly is determined during the first drilling operation. This dissertation consists of three papers which consider the influence of various factors on hole positional accuracy when drilling in inclined workpieces using high-speed steel twist drills with conventional point geometry. LÄS MER

  7. 5. Challenges in Resistance Welding of Ultra High Strength Steels

    Författare :Erik Tolf; Arne Melander; Zuheir Barsoum; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Resistance welding; spot welding; surface cracks; nut welding; UHSS; projection welding; Teknisk materialvetenskap; Materials Science and Engineering;

    Sammanfattning : Increasing the use of Ultra High Strength Steels (UHSS) in vehicle bodystructures is important for reducing weight and cutting CO2 emissions. This thesis investigates challenges in resistance welding that can be a barrier to implementing UHSS as a replacement for low strength steels in vehicle structures. LÄS MER