Search for dissertations about: "Acoustic impedance"

Showing result 1 - 5 of 49 swedish dissertations containing the words Acoustic impedance.

2. 1. Acoustic characterization of orifices and perforated liners with flow and high-level acoustic excitation

   Author : Lin Zhou; Hans Bodén; Wim De Roeck; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Bias Flow; Grazing Flow; Nonlinear Acoustics; Acoustic Impedance; Impedance Eduction; Single Mode Straightforward Method; Uncertainty Analysis; LEE; LNSE; Järnvägsgruppen - Ljud och vibrationer; Järnvägsgruppen - Ljud och vibrationer;

   Abstract : This thesis is motivated by the need for noise control in aircraft engine with orifices and perforated liner. The presence of high-level acoustic excitation, different flow situations either bias flow, grazing flow or any combination in the aircraft engine, makes the acoustic behavior complex due to the interaction between sound and flow over the lined wall. READ MORE

4. 2. Acoustic Forces in Cytometry and Biomedical Applications: Multidimensional Acoustophoresis

   Author : Carl Grenvall; Avdelningen för Biomedicinsk teknik; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Acoustophoresis; Microfluidics; Ultrasound; Multinode; Cell Sorting; Particle Positioning; Cytometry; Lab-on-a-Chip; µTAS; Binary Separation; Acoustic Barriers; Acoustic Particle Manipulation; Acoustic Standing Waves; Blood Separation; Milk Analysis;

   Abstract : Over the last decades the ongoing work in the fields of Lab-on-a-Chip and Micro-Total-Analysis-Systems has led to the discovery of new or improved ways to handle and analyse small volumes of biofluids and complex biosuspensions. The benefits of working on the microscale include: miniaturization of the analysis systems with less need for large sample volumes; temporal and spatial control of suspended particle/cell positions; low volume sheath flow lamination or mixing; novel separation techniques by using forces inherent to the microscale domain; precise regulation of sample temperatures and rapid analysis with less volumes needed to be processed. READ MORE

5. 3. Experimental Investigation of the Acoustic Properties of Perforate using Acoustic Three-Ports

   Author : Shail A. Shah; Susann Boij; Hans Bodén; Wim De Roeck; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Duct Acoustics; Acoustical Three-port; Perforated plate; Transfer Impedance; Scattering Matrix; Grazing Flow; High-level Excitation; Non-linear effects; Flow-Acoustic Interaction; Rectangular T-Junction; Farkostteknik; Vehicle and Maritime Engineering;

   Abstract : This thesis discusses the aero-acoustic characterisation of a perforate sample using a three-port technique. A rectangular T-junction with a flush mounted perforated sample at the intersection form the acoustical three-port. 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. Assessing precision and accuracy in acoustic scattering matrix measurements

   Author : Luck Peerlings; Hans Bodén; Susann Boij; Avraham Hirschberg; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; aero-acoustics; sudden area expansion; in-duct acoustics; acoustic scattering matrix; impedance tube; uncertainty analysis; systematic errors; Vehicle and Maritime Engineering; Farkostteknik;

   Abstract : Acoustic scattering matrices are used to characterize the influence of inline duct elements on the acoustic wave propagation in wave guides.When measuring the properties of these matrices, errors are always present in the results and need to be characterized to make valid statements on the correspondence between model predictions and measurements. READ MORE