Sökning: "acoustic source"

Visar resultat 1 - 5 av 133 avhandlingar innehållade orden acoustic source.

1. 1. Acoustic source characterisation for non-linear in-duct sources

   Författare :Fredrik Albertson; KTH; []
   Nyckelord :in-duct source; source characterisation; non-linear source; linearity test; hybrid method; IC-engine; muffler; coupling method;

   Sammanfattning : Different ways to model acoustic in-duct sources have beenanalysed. Measurements were conducted on two diesel truckengines. It was found that for steady state oscillations, onecould linearise in the neighbourhood of a given linearisationpoint, i.e. LÄS MER

3. 2. Studies of flow duct acoustics with applications to turbocharged engines

   Författare :Hans Rämmal; Hans Boden; Mats Åbom; Antonio Torregrosa; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; IC-engine; turbocharger; duct termination; flow duct; exhaust system; inlet system; acoustic source; one-port; two-port; source model; transmission loss; two-port matrix; reflection coefficient; source strength; multi-load method; Acoustics; Akustik;

   Sammanfattning : A number of experimental and theoretical studies, performed in the field of technical flow duct acoustics are presented in this thesis. The acoustical methods treated are implemented on turbocharged IC-engines and engine gas exchange system components. A new method based on the well-known two-load technique has been developed. LÄS MER

4. 3. Acoustic In-duct Characterization of Fluid Machines with Applications to Medium Speed IC-engines

   Författare :Antti Hynninen; Mats Åbom; Hans Bodén; Antonio Torregrosa; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; in-duct; acoustic source; source characterization; IC-engine;

   Sammanfattning : The unwanted sound, noise, can lead to health problems, e.g. hearing loss and stress-related problems. A pre-knowledge of noise generation by machines is of great importance due to the ever-shorter product development cycles and stricter noise legislation. LÄS MER

5. 4. Computational Aeroacoustics Based on Large Eddy Simulation and Acoustic Analogies

   Författare :Mihai Mihaescu; Laszlo Fuchs; Strömningsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Mechanical engineering; hydraulics; plasma; Technological sciences; Teknik; fluiddynamik; plasmas; Gaser; fluid dynamics; Gases; Inhomogeneous Wave Equation; Acoustic Boundary Conditions; Acoustic Source Terms; LES; Computational Aeroacoustics; Turbulent Flows; vacuum technology; vibration and acoustic engineering; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik; Computational Aeroacoustics;

   Sammanfattning : The thesis presents a numerical method developed by the author and its applications for computing the generated sound by an unsteady flow field and its propagation. The full equations of motion for compressible and unsteady flows describe both flow field and sound generation and propagation. LÄS MER

7. 5. Acoustic Sound Source Localisation and Tracking : in Indoor Environments

   Författare :Anders Johansson; Blekinge Tekniska Högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Room acoustics; Speaker localisation; Tracking; State-space filter; Sequential Monte Carlo method; Particle filter;

   Sammanfattning : With advances in micro-electronic complexity and fabrication, sophisticated algorithms for source localisation and tracking can now be deployed in cost sensitive appliances for both consumer and commercial markets. As a result, such algorithms are becoming ubiquitous elements of contemporary communication, robotics and surveillance systems. LÄS MER