Makine Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.11779/1944

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Department: search.filters.department.Mühendislik Fakültesi, Makine Mühendisliği BölümüPublisher: search.filters.publisher.Acoustical Society of America

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Now showing 1 - 2 of 2
  • Article
    Citation - WoS: 8
    Citation - Scopus: 10
    Displacement of a Bubble Located at a Fluid-Viscoelastic Medium Interface
    (Acoustical Society of America, 2019) Körük, Hasan; Körük, Hasan; Choi, James J.; 02.03. Department of Mechanical Engineering; 02. Faculty of Engineering; 01. MEF University
    A model for estimating the displacement of a bubble located at a fluid-viscoelastic medium interface in response to acoustic radiation force is presented by extending the model for a spherical object embed- ded in a bulk material. The effects of the stiffness and viscosity of the viscoelastic medium and the amplitude and duration of the excitation force on bubble displacement were investigated using the proposed model. The results show that bubble displacement has a nonlinear rela- tionship with excitation duration and viscosity. The time at which the steady state is reached increases with increasing medium viscosity and decreasing medium stiffness.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    The Effects of Ultrasound Parameters and Microbubble Concentration on Acoustic Particle Palpation
    (Acoustical Society of America, 2018) Körük, Hasan; Körük, Hasan; Saharkhiz, Niloufar; Choi, James J; 02.03. Department of Mechanical Engineering; 02. Faculty of Engineering; 01. MEF University
    The elasticity of tissue—an indicator of disease progression—can be imaged by ultrasound elasticity imaging technologies. An acoustic particle palpation (APP) has recently been developed—the use of ultrasonically driven acoustic particles (e.g., microbubbles)—as an alternative method of tissue deformation. APP has the potential to improve the resolution, contrast, and depth of ultrasound elasticity imaging; but the tissue displacement dynamics and its dependence on acoustic pressure, center frequency, and microbubble concentration remains unknown. Here, displacements of at least 1 μm were produced by applying ultrasound onto a microbubble solution (concentration: 10 × 106 microbubbles ml–1) placed within a tunnel surrounded by a 5% gelatin phantom. Displacements of more than 10 μm were produced using a 1, 3.5, or 5 MHz center frequency pulse with peak-rarefactional pressures of 470, 785, and 1210 kPa, respectively. The deformation of the distal wall varied spatially and temporally according to the different parameters investigated. At low pressures, the deformation increased over several milliseconds until it was held at a nearly constant value. At high pressures, a large deformation occurred within a millisecond followed by a sharp decrease and long stabilization. Ultrasound exposure in the presence of microbubbles produced tissue deformation (p < 0.05) while without microbubbles, no deformation was observed.