Sökning: "sound radiation"

Visar resultat 11 - 15 av 46 avhandlingar innehållade orden sound radiation.

1. 11. Studies of sound generation and propagation in flow ducts

   Författare :Fabrice Ducret; Mats Åbom; Andy Moorhouse; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; two-port; plane wave; HVAC system; tailpipe; exhaust system; flexible duct; pipe; reflection coefficient; impedance; flow noise; vorticity; damping; scaling laws; impedance; transmission loss; perforated plate; slit; non linearity; Acoustics; Akustik;

   Sammanfattning : This thesis contains three papers investigating problems of interest for noise control in ducts. The first part of this thesis treats the sound propagation in rectangular ducts with flexible walls. Various experimental techniques are performed to measure the internal sound propagation and radiation to the surrounding. LÄS MER

3. 12. Assessing and modelling impact sound insulation of wooden joist constructions

   Författare :Wanqing Shi; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Teknisk akustik; Engineering Acoustics;

   Sammanfattning : Impact sound insulation is one of the most important aspects when assessing sound insulation of floor constructions in buildings. For assessing the impact sound insulation of aconstruction, a standard tapping machine is used as a sound source. LÄS MER

4. 13. Active Noise Control of Enclosed Sound Fields Optimising the Performance

   Författare :Per Sjösten; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; optimising actuator and sensor positions; hybrid controller for anc; fast feedforward algorithm; multiple-error algorithm; active noise control; complex lms; multichannel feedforward algorithm; simulated annealing; mean-field annealing; multiple-reference controller;

   Sammanfattning : Active noise control is the art of reducing a primary unwanted sound field by interference with an actively created secondary sound field. To achieve high reduction, it is crucial to obtain both temporal and spatial matching between the primary and the secondary sound fields. LÄS MER

5. 14. Investigation of acoustic source characterisation and installation effects for small axial fans

   Författare :Per-Olof Berglund; KTH; []
   Nyckelord :axial fan; airborne sound; source characterisation; transmission path analysis; in-duct. Spherical harmonics;

   Sammanfattning : Fans are often used in equipment such as home appliances andelectronic equipment where the margin of profit is small butcustomers demands on a low noise level are high. Therefore,methods for predicting the noise emitted by an applicationincluding one or several fans are desirable in order toimprove, accelerate and reduce the cost of low-noise design. LÄS MER

7. 15. 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