Sökning: "the Doppler factor"

Visar resultat 1 - 5 av 44 avhandlingar innehållade orden the Doppler factor.

1. 1. A Novel Signal Model and Estimation Method for Acoustic Doppler Current Meters

   Författare :Thomas L Lagö; Teknisk akustik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Doppler Profiler; Acoustic Doppler; Gaussian Backscattering Model; ADCM; ADCP; The Symmiktos Method; Estimation; Doppler; Current; MPCA.; Technological sciences; Teknik; Electromagnetism; optics; acoustics; Elektromagnetism; optik; akustik;

   Sammanfattning : This thesis deals with the process of estimating underwater current from the backscattering signal transmitted from an ultrasonic transducer. The narrowband sinusoidal burst signal is Doppler-shifted due to the current, and this information is converted into current. LÄS MER

3. 2. On the Directivity of Railway Noise Sources

   Författare :Xuetao Zhang; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; railway traction noise; railway rolling noise; line source; railway aerodynamic noise; moving source; equivalent source line; De-Dopplerization; sound emission time; sound immission time; directivity; the Doppler factor;

   Sammanfattning : This dissertation deals with the directivity of railway noise. The directivity of railway noise is of particular importance when we have high-rise buildings close to the track, tunnel openings, partial barriers, or when we calculate the maximum sound pressure level during a pass-by based on the sound power level of the different sub-sources of a train. LÄS MER

4. 3. Laser Doppler perfusion imaging : methodology and skin applications

   Författare :Karin Wårdell; Linköpings universitet; []
   Nyckelord :MEDICINE; MEDICIN;

   Sammanfattning : Over the last decade a number of emerging technologies have become available for the non-invasive study of skin anatomy and physiology. In this thesis, a method for mapping tissue perfusion based on the laser Doppler technique is presented together with some of the associated experimental and clinical applications. LÄS MER

5. 4. Gastrointestinal mucosal protective mechanisms : Mudolatory effects of Heliobacter pyroli on the gastric mucus gel barrier and mucosal blood flow in vivo

   Författare :Christer Atuma; Uppsala universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Physiology and anatomy; mucus gel layer; mucosal blood flow; mucus thickness; chronic infection; rat; platelet activating factor; mast cell; nitric oxide; nitric oxide synthase; ketotifen; intra-vital microscopy; microelectrode; laser-Doppler flowmetry; L-NNA; Fysiologi och anatomi; Physiology and pharmacology; Fysiologi och farmakologi; Physiology; fysiologi;

   Sammanfattning : The gastrointestinal mucus gel layer and blood flow are two important mechanisms for protection at the pre-epithelial and sub-epithelial levels, respectively. Helicobacter pylori might circumvent these mechanisms and elicit a chronic inflammatory response with consequent ulcers in the stomach and duodenum. LÄS MER

7. 5. On perfusion estimation using ultrasound

   Författare :Tomas Jansson; Avdelningen för Biomedicinsk teknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Instrumentation technology; Speckle; Artifacts; Perfusion; Ultrasound; Doppler; Mät- och instrumenteringsteknik;

   Sammanfattning : This thesis has the main focus on ways to improve the blood perfusion estimate, as obtained from a continuous wave Doppler system. Earlier studies have shown large temporal variations in the detected perfusion estimate, due to speckle. LÄS MER