Sökning: "impact excitation"

Visar resultat 16 - 20 av 76 avhandlingar innehållade orden impact excitation.

  1. 16. The Invasion of the Zebra Mussel - Effects on Phytoplankton Community Structure and Ecosystem Function

    Författare :Rahmat Naddafi; Kurt Pettersson; Peter Eklöv; Willem Goedkoop; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Invasive species; Zebra mussel; Invasion success; Selective feeding; Non-lethal effects of predator; Seston stoichiometry; Delayed fluorescence excitation spectroscopy; Phytoplankton dynamics; Trait-mediated indirect interaction; Ecosystem function;

    Sammanfattning : Biological invasion has become a major threat to economy, ecology, global biodiversity and ecosystem function of aquatic ecosystems. The main aim of the thesis was to study the effects of the zebra mussel (Dreissena polymorpha), a versatile invasive species, on phytoplankton dynamics and ecosystem function of lakes. LÄS MER

  3. 17. Picosecond X-ray Diffraction Studies of Bulk and Nanostructure Materials

    Författare :Andrius Jurgilaitis; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; solid-liquid transitions; X-ray diffraction and scattering; nanowires; laser beam impact phenomena; phonons in crystal lattices; Fysicumarkivet A:2012:Jurgilaitis;

    Sammanfattning : Fast phenomena occurring after laser excitation were studied using time-resolved X-ray diffraction (TXRD). In most experiments, a femtosecond laser pulse was used to excite the sample, and X-rays were used as a probe. LÄS MER

  4. 18. Mechanical impedance gauge based on measurement of strains on a vibrated or impacted rod

    Författare :Lars Lagerkvist; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hållfasthetslära; Solid Mechanics;

    Sammanfattning : A mechanical impedance gauge based on measurement of strains at two cross-sections of a slender rod is studied. The gauge rod is in contact with the object at one end while the other end is excited harmonically with a vibrator or transiently through the impact of a hammer. LÄS MER

  5. 19. Vibrations induced by surface roughness in nonlinear rolling contacts

    Författare :Oskar Erik Lundberg; Ines Lopez Arteaga; Svante Finnveden; Will Graham; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Rolling contact; nonlinear contact; contact stiffness; contact filter; state-dependent method; relative displacement; wheel-rail contact; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : For efficient transportation in either trains, busses or passenger cars, rolling elements such as wheels, tyres, bearings and transmission elements are fundamental. The energy efficiency and the generation of noise and vibrations in rolling contacts depend on the surface roughness of contacting bodies. LÄS MER

  7. 20. Low-cost control of discontinuous systems including impacts and friction

    Författare :Fredrik Svahn; Annika Stensson Trigell; Harry Dankowicz; Jenny Jerrelind; Remco Leine; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; nonlinear dynamics; discontinuities; nonlinear control; impacts; friction; vehicle suspensions; Vehicle engineering; Farkostteknik;

    Sammanfattning : For a successful design of an engineering system it is essential to pay careful attention to its dynamic response. This is particularly true, in the case of nonlinear systems, since they can exhibit very complex dynamic behaviour, including multiple co-existing stable solutions and chaotic motions, characterized by large sensitivity to initial conditions. LÄS MER