Sökning: "mechanical impedance"

Visar resultat 6 - 10 av 97 avhandlingar innehållade orden mechanical impedance.

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

   Författare :Lin Zhou; Hans Bodén; Wim De Roeck; KTH; []
   Nyckelord :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;

   Sammanfattning : 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. LÄS MER

3. 7. Innovative noise control in ducts

   Författare :Maaz Farooqui; Mats Åbom; Hans Bodén; Tamer Elnady; Jeong-Guon Ih; KTH; []
   Nyckelord :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;

   Sammanfattning : 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. LÄS MER

4. 8. Virtual prototyping of vehicular electric steering assistance system using co-simulations

   Författare :Weitao Chen; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; coupling method; explicit parallel co-simulation; HIL simulation; interface algorithm.; Vehicle and mechatronic system;

   Sammanfattning : Virtual prototyping is a practical necessity in vehicle system development. From desktop simulation to track testing, several simulation approaches, such as co-simulation and hardware-in-loop (HIL) simulation, are used. However, due to interfacing problems, the consistency of testing results may not be ensured. LÄS MER

5. 9. Transducers for impact force and mechanical impedance based on strain measurement

   Författare :Karl-Gustaf Sundin; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hållfasthetslära; Solid Mechanics;

   Sammanfattning : Transducers for impact force and mechanical point impedance are studied. In both cases the transducers are based on resistive strain measurement. Two prototypes of impact force transducers based on different concepts of mean strain measurement are developed and tested. The results are satisfactory and show that the suggested concepts are suitable. LÄS MER

7. 10. Transpulmonary pressure during mechanical ventilation

   Författare :Christina Grivans; Göteborgs universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Mechanical ventilation; Acute lung injury; Acute respiratory distress syndrome; Lung volume measurements; Electric Impedance diagnostic use; Lung elastance; Transpulmonary pressure; Esophageal pressure;

   Sammanfattning : Background: Mechanical ventilation can aggravate lung injury by repetitive opening and closing of lung units, overdistention and undue pressure on pulmonary structures. Guidelines exist for lung protective ventilation, but individualized ventilator settings, based on partitioning of respiratory mechanics in pulmonary and chest wall complex components, would be beneficial. LÄS MER