Sökning: "impact excitation"

Visar resultat 1 - 5 av 76 avhandlingar innehållade orden impact excitation.

1. 1. Two-Dimensional Signal Root Estimation in Blind Multichannel Impact Response Analysis

   Författare :Joakim Axmon; Matematisk statistik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; forestry; Silviculture; detection of decay.; Norway spruce; X-texture mode; signal subspace enhancement; partial forward-backward averaging; ESPRIT; state-space; Prony; frequency analysis; SIMO; impact response; Modal analysis; impact excitation; forestry technology; Skogsvetenskap; skogsbruk; skogsteknik; Electrical engineering; Elektroteknik; Signal processing; Signalbehandling;

   Sammanfattning : This doctoral dissertation concerns two-dimensional frequency estimation for modal analysis of single-input multiple-output impact responses from circularly cylindrical objects. The application is within detection of internal defects in trunks of spruce. LÄS MER

3. 2. Acoustic excitation and transmission of lightweight structures

   Författare :Jonas Brunskog; Teknisk akustik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; point mobility; Lamb waves; wood.; Building construction; plate excitation; cavities; near-periodicity; nearly periodic; sound insulation; timber; structural acoustics; spatial Fourier transform; resilient device; prediction model; periodic; lightweight; ISO tapping machine; airborne noise; Building acoustics; impact noise; Byggnadsteknik;

   Sammanfattning : In order to increase our knowledge of the sound transmission and radiation processes of lightweight wall and floor structures, theoretical models are needed. Detailed models may form a valuable tool. In lightweight floor structures, impact sound insulation is perhaps the most important property to consider. LÄS MER

4. 3. Studies of Light Emitting Devices Based on Er-doped Si and SiGe Layered Structures

   Författare :Chun-Xia Du; Fransesco Priolo; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; electroluminescence; diode; transistor; hot electron; recombination; excitation; de-excitation; Auger effect; molecular beam epitaxy; Er; Si; SiGe;

   Sammanfattning : Doping with rare earth element erbium (Er) in Si has recently attracted a lot of research interest due to potential applications in Si-based opto-electronics. By using molecular beam epitaxy (MBE), precipitate-free Er-doping in Si has been made together with other co-dopants, e.g., oxygen (0) and fluorine (F), up to a level ∼1020 cm-3. LÄS MER

5. 4. Low Frequency Impact Sound in Timber Buildings : Simulations and Measurements

   Författare :Jörgen Olsson; Andreas Linderholt; Leif Kari; Linnéuniversitetet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Low-frequency; impact sound; light weight floor; timber joist floor; tapping machine; multi-storey timber building; frequency response functions.; Stegljud; Byggteknik; Civil engineering;

   Sammanfattning : An increased share of construction with timber is one possible way of achieving more sustainable and energy-efficient life cycles of buildings. The main reason is that wood is a renewable material and buildings require a large amount of resources. LÄS MER

7. 5. Identification of Viscoelastic Materials by Use of Wave Propagation Methods

   Författare :Saed Mousavi; Bengt Lundberg; Urmas Valdek; Janne Färm; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering physics; Identification; Viscoelastic; Complex modulus; Complex Poisson s ratio; wave; Impact; Teknisk fysik; Engineering physics; Teknisk fysik;

   Sammanfattning : Complex moduli and Poisson’s ratio have been estimated using extensional and torsional wave experiments. The data were used for assessment of linearity and isotropy of two polymers, polymethyl methacrylate (PMMA) and polypropylene (PP). The responses of both materials were found to be close to linear and isotropic. LÄS MER