Sökning: "Mats Boij"

Visar resultat 6 - 10 av 10 avhandlingar innehållade orden Mats Boij.

  1. 6. Aeroacoustic Characterization using Multiport Methods

    Författare :Andreas Holmberg; Hans Bodén; Mats Åbom; Susann Boij; Lars Enghardt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeroacoustics; Multiport; Experiments; Computational Aeroacoustics; Mixer Plate; T-junction.;

    Sammanfattning : Noise is a major environmental pollutant, which can inict physical and psychologicalinjury. An important noise contribution stems from aeroacousticsources, which are found in e.g., ventilation ducts, engine exhaust systems andairplane engines. LÄS MER

  3. 7. Graded Betti Numbers and Hilbert Functions of Graded Cohen-Macaulay Modules

    Författare :Jonas Söderberg; Mats Boij; Jürgen Herzog; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; MATHEMATICS; MATEMATIK;

    Sammanfattning : In this thesis we study graded Cohen-Macaulay modules and their possible Hilbert functions and graded Betti numbers. In most cases the Cohen-Macaulay modules we study are level modules. LÄS MER

  4. 8. Modeling of sound-turbulence interaction in low-Mach-number duct flows

    Författare :Chenyang Weng; Mats Åbom; Susann Boij; Avraham Hirschberg; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Järnvägsgruppen - Ljud och vibrationer; Järnvägsgruppen - Ljud och vibrationer;

    Sammanfattning : When sound waves propagate in a duct in the presence of turbulent flow, tur- bulent mixing can cause extra attenuation of the sound waves in addition to that caused by the viscothermal eects. Experiments show that compared to the vis- cothermal eects, turbulent absorption becomes the dominant contribution to the sound attenuation at suciently low frequencies. LÄS MER

  5. 9. Theoretical and numerical studies of sound propagation in low-Mach-number duct flows

    Författare :Chenyang Weng; Mats Åbom; Susann Boij; Ardeshir Hanifi; Anurag Agarwal; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeroacoustics; Acoustic wave absorption; Acoustic wave propagation; Boundary layer turbulence; DNS; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : When sound waves propagate in a duct in the presence of turbulent flow, turbulent mixing can cause attenuation of the sound waves extra to that caused by the viscothermal effects. Experiments show that compared to the viscothermal effects, this turbulent absorption becomes the dominant contribution to the sound attenuation at sufficiently low frequencies. LÄS MER

  7. 10. Around minimal Hilbert series problems for graded algebras

    Författare :Lisa Nicklasson; Samuel Lundqvist; Christian Gottlieb; Uwe Nagel; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Graded algebras; Hilbert series; Lefschetz properties; Exterior algebra; Linear resolution; Mathematics; matematik;

    Sammanfattning : The Hilbert series of a graded algebra is an invariant that encodes the dimension of the algebra's graded compontents. It can be seen as a tool for measuring the size of a graded algebra. This gives rise to the idea of algebras with a "minimal Hilbert series", among the algebras within a certain family. LÄS MER