Sökning: "Ultrasonic waves"

Visar resultat 1 - 5 av 35 avhandlingar innehållade orden Ultrasonic waves.

  1. 1. Ultrasonic Arrays for Sensing and Beamforming of Lamb Waves

    Författare :Marcus Engholm; Tadeusz Stepinski; Paul D. Wilcox; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; imaging; array processing; guided waves; Lamb waves; dispersive waves; multi-modal waves; spatial filtering; mode suppression; resonant ultrasound; transducer design; direction of arrival estimation; adaptive beamforming; Signal processing; Signalbehandling; Electronic measurement and instrumentation; Elektronisk mät- och apparatteknik;

    Sammanfattning : Non-destructive testing (NDT) techniques are critical to ensure integrity and safety of engineered structures. Structural health monitoring (SHM) is considered as the next step in the field enabling continuous monitoring of structures. LÄS MER

  3. 2. Nonlinear Interaction Between Ultrasonic Waves and Cracks and Interfaces

    Författare :Milan Poznic; Leif Kari; Bruce Drinkwater; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; ultrasonic waves; crack; modulation; rough interface; partially closed; surface-breaking; fluid-filled; Acoustics; Akustik;

    Sammanfattning : The subject of this thesis is the development of new ultrasound inspection techniques for detection of cracks that are smaller than the wavelength of the inspecting wave and the characterization of cracks in fluid-filled pipes as either surface-breaking or subsurface. The spectrum of the scattered field of a partially closed crack comprises harmonic components not expected to be found in the case of linear scatterers such as pores or inclusions. LÄS MER

  4. 3. Non-destructive measurement of near-surface cracks in railheads : with focus on ultrasonic inspections

    Författare :Rayendra Anandika; Jan Lundberg; Paul Wilcox; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; rail inspection; phased array; ultrasonic testing; eddy current testing; surface cracks; non-destructive testing; NDT; railway; condition monitoring; Drift och underhållsteknik; Operation and Maintenance;

    Sammanfattning : Near-surface cracks in railhead that caused by rolling contact fatigue (RCF) is one of a kind rail defects that degrade rail track quality. Dependent on the trail load, the cracks can reach to severe level quickly. LÄS MER

  5. 4. Modelling crack-induced ultrasonic scattering in a thick-walled pipe

    Författare :Jacob Rubenson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Cylindrical pipes; Non-Destructive Testing; Crack; Ultrasonic waves; Hypersingular integral method;

    Sammanfattning : Ultrasonic testing is used in several industries where there are high demands on safety, e.g. nuclear power and aerospace industries. In the nuclear industry and elsewhere there are many pipes that need to be tested. LÄS MER

  7. 5. Cell and Particle Trapping in Microfluidic Systems Using Ultrasonic Standing Waves

    Författare :Mikael Evander; Avdelningen för Biomedicinsk teknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustic particle manipulation; standing waves; trapping; ultrasound; cell handling; particle handling; Microsystem technology; lab on a chip; microfluidics;

    Sammanfattning : Analysis methods are currently being miniaturized in order to save time and money while achieving higher sensitivities. The ultimate goal is to create a lab-on-a-chip where all analysis steps and instruments can be automated and integrated into a single chip. LÄS MER