Search for dissertations about: "porous absorbers"

Showing result 1 - 5 of 8 swedish dissertations containing the words porous absorbers.

2. 1. The use of Textiles in an Acoustic Context

   Author : Karl Tillberg; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; porous absorbers; knitted fabric; woven fabric; helmholtz absorbers; room acoustics; nonwoven material; classroom; acoustic textiles; resonance absorbers; panel absorbers;

   Abstract : Working with textiles in an acoustic context gives enormous possibilities to combine the acoustic function of materials with the visual function (aesthetics). Depending on the material choice and the production techniques, textiles may for instance be flexible, stiff, airtight, have high density or high porosity. READ MORE

4. 2. Absorption of Sound : On the effects of field interaction on absorber performance

   Author : Anna Färm; Mats Åbom; Ragnar Glav; Susann Boij; Gareth Bennett; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound absorption; Porous absorbers; Bulk reaction; Local reaction; Boundary layer; Grazing flow; Temperature gradients; Surface impedance; Sound field; Pass-by noise; Vehicle and Maritime Engineering; Farkostteknik;

   Abstract : Environmental noise has for decades been a well known problem, especially in urban areas. As noise requirements for vehicles are sharpened, noise reducing concepts are needed in early design stages requiring accurate simulations to support the design. READ MORE

5. 3. Absorption Characteristics of Periodically Perforated Suspended Ceilings

   Author : Dag Holmberg; Teknisk akustik; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Building construction; Byggnadsteknik; measurement device.; flow resistance; suspended ceilings; periodically perforated facing; resonant absorbers; Room acoustics; building acoustics;

   Abstract : The sound absorption characteristics of resonant absorbers, implemented as perforated suspended inner ceilings attached with thin porous layers, are investigated. Several existing theories model the principal absorption mechanisms, but the interaction with the outer sound field influences the absorption in ways that can be modelled with new approaches. READ MORE

6. 4. Innovative noise control in ducts

   Author : Maaz Farooqui; Mats Åbom; Hans Bodén; Tamer Elnady; Jeong-Guon Ih; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Locally resonant materials; slow sound; acoustic impedance; metallic foam; low frequency noise; mufflers; lined ducts; grazing flow; flow duct; impedance eduction.; Vehicle and Maritime Engineering; Farkostteknik;

   Abstract : The objective of this doctoral thesis is to study three different innovative noise control techniques in ducts namely: acoustic metamaterials, porous absorbers and microperforates. There has been a lot of research done on all these three topics in the context of duct acoustics. READ MORE

7. 5. Modelling of thin and imperfect interfaces : Tools and preliminary study

   Author : Mathieu Gaborit; Peter Göransson; Olivier Dazel; Émeline Sadoulet-Reboul; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; thin layers; numerical methods; FEM; poroelastic materials; couches fines; méthodes numériques; MEF; matériaux po- roélastiques; Engineering Mechanics; Teknisk mekanik;

   Abstract : For quite some time, the strive for more efficient acoustic absorbers keepsincreasing, driven by a number of psycho-physiological studies on health re-lated dangers of noise exposure. As the global wealth increases and with itthe global expectation of quieter living and working environments, manifestedin both politics and research, an important market for sound absorbing andnoise control systems develops in all industrialised countries. READ MORE