Yazar "Korozlu, Nurettin" seçeneğine göre listele

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    Acoustic sorting of airborne particles by a phononic crystal waveguide
    (Elsevier, 2022) Korozlu, Nurettin; Bicer, Ahmet; Sayarcan, Done; Kaya, Olgun Adem; Cicek, Ahmet
    A two-dimensional phononic crystal linear defect waveguide is utilized for size-based sorting of millimeter-sized solid particles in the air through acoustic radiation force. The waveguide channels ultrasonic waves at 20 kHz, as calculated through Finite-Element Method simulations. Spherical solid particles released from rest at the top of the vertically aligned waveguide experience the combined effect of the acoustic radiation, gravity, and drag forces. When the particles are released from the symmetry plane of the waveguide, they follow straight paths where the ones with radii smaller than a threshold value are trapped at the waveguide nodal planes, whereas larger particles are let pass through. This requires input sound pressure levels between 173 dB and 177 dB. Moreover, such particles can also be differentiated with respect to density. Alternatively, the release of particles with a slight offset from the symmetry center induces unbalanced acoustic radiation potential, and thus uneven radiation force, resulting in the initiation of horizontal displacement whose extent depends on particle radius. Thus, both simulation results and experimental findings suggest that this scheme can be employed in size-based particle separation. Sorting of spherical glass particles with 0.5 mm and 1.0 mm radii are experimentally demonstrated for low ultrasonic transducer acoustic power output up to 90 W. The proposed approach can be utilized in applications where contact-free separation of airborne particles is required.
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    Acoustic tamm states of three-dimensional solid-fluid phononic crystals
    (Acoustıcal soc amer amer ınst physıcs, ste 1 no 1, 2 huntıngton quadrangle, melvılle, ny 11747-4502 usa, 2018) Korozlu, Nurettin; Kaya, Olgun Adem; Cicek, Ahmet; Ulug, Bulent
    In this work, the existence and propagation of acoustic Tamm states at the interface of air and a face-centered cubic solid-fluid phononic crystal composed of spherical air voids interconnected by cylindrical air channels are demonstrated. Supercell band structure computations via the finite element method reveal surface bands for Tamm states on (100), (110), and (111) surfaces of the phononic crystal. The states decay sharply into the phononic crystal so that only a two-row slab is sufficient to guide them over the respective surfaces without leakage, as confirmed by finite element simulations. In addition, surface wave propagation along the [10] direction of the (100) surface is experimentally demonstrated. Ability to confine the Tamm states in all three dimensions is a key aspect in designing few-layer-thick acoustic circuits. Low material filling fraction of the phononic crystal could be leveraged to realize lightweight all-acoustic systems where either bulk or surface states can be incorporated. (C) 2018 Acoustical Society of America.
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    Acoustic Tamm states of three-dimensional solid-fluid phononic crystals
    (Acoustical Soc Amer Amer Inst Physics, 2018) Korozlu, Nurettin; Kaya, Olgun Adem; Cicek, Ahmet; Ulug, Bulent
    In this work, the existence and propagation of acoustic Tamm states at the interface of air and a face-centered cubic solid-fluid phononic crystal composed of spherical air voids interconnected by cylindrical air channels are demonstrated. Supercell band structure computations via the finite element method reveal surface bands for Tamm states on (100), (110), and (111) surfaces of the phononic crystal. The states decay sharply into the phononic crystal so that only a two-row slab is sufficient to guide them over the respective surfaces without leakage, as confirmed by finite element simulations. In addition, surface wave propagation along the [10] direction of the (100) surface is experimentally demonstrated. Ability to confine the Tamm states in all three dimensions is a key aspect in designing few-layer-thick acoustic circuits. Low material filling fraction of the phononic crystal could be leveraged to realize lightweight all-acoustic systems where either bulk or surface states can be incorporated. (C) 2018 Acoustical Society of America.
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    Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens
    (Nature Portfolio, 2017) Cicek, Ahmet; Korozlu, Nurettin; Kaya, Olgun Adem; Ulug, Bulent
    We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.
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    Broad omnidirectional acoustic band gaps in a three-dimensional phononic crystal composed of face-centered cubic Helmholtz resonator network
    (Acoustical Soc Amer Amer Inst Physics, 2021) Bicer, Ahmet; Korozlu, Nurettin; Kaya, Olgun A.; Cicek, Ahmet
    Broad omnidirectional band gaps in a three-dimensional phononic crystal consisting of a face-centered cubic array of spherical air voids connected by cylindrical conduits in solid background are numerically and experimentally demonstrated. With a low material filling fraction of 37.7%, the first bandgap covers 3.1-13.6 kHz frequency range with 126.1% gap-over-midgap ratio. Finite-element method is employed in band structure and numerical transmission analyses. Omnidirectional band gaps are observed in only two-period thick slabs in the 100, 110, and 111 orientations. Experimental transmission characteristics are in good agreement with numerical data. The phononic crystal can be employed in low-frequency sound proofing.& nbsp;(C) 2021 Acoustical Society of America
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    Gas sensing through evanescent coupling of spoof surface acoustic waves
    (Elsevier Science Sa, 2019) Cicek, Ahmet; Arslan, Yasin; Trak, Digdem; Okay, Fatih Can; Kaya, Olgun Adem; Korozlu, Nurettin; Ulug, Bulent
    An ultrasonic gas sensor based on evanescent coupling of spoof surface acoustic waves between two surface phononic crystals containing trapezoidal grooves on rigid slabs is theoretically and experimentally demonstrated. Sensing properties for carbon dioxide in dry air at 25 degrees C and 760 Torr are investigated as an example. Band structure analyses reveal two spoof surface acoustic wave bands with opposite parities when the separation of surface phononic crystals is 1.5 times the periodicity of grooves. The beat length varies with frequency and carbon dioxide volume fraction, where the increase of the latter results in red shift of a sharp intense output peak at 59.69 kHz at a rate of 17.70 mHz/ppm and 16.20 mHz/ppm for carbon dioxide volume fractions up to 10,000 ppm, as measured through Finite-Element Method simulations and experiments, respectively. Gas sensing can also be achieved by measuring the output acoustic intensity at constant frequency, which exhibits a steep decrease with carbon dioxide volume fraction up to 2000 ppm.
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    One-dimensional surface phononic crystal ring resonator and its application in gas sensing
    (Amer Inst Physics, 2019) Kaya, Olgun Adem; Korozlu, Nurettin; Trak, Digdem; Arslan, Yasin; Cicek, Ahmet
    We introduce a ring resonator, which employs a one-dimensional phononic crystal on its inner surface, and investigate its performance as a gas sensor both numerically and experimentally. Having periodic equilateral trapezoidal protrusions, the ring resonator with 207 periods is optimized through band structure calculations via the finite-element method. A surface band linear around 58kHz is observed. The resonator exhibits sharp transmission peaks with a broad free-spectral range of 0.54kHz. Accordingly, a peak at 58.49kHz with a high-quality factor of 8196 appears. Application in detection of the carbon dioxide level in air with high sensitivity is demonstrated. The 58.49kHz peak red shifts linearly at 17.3mHz/ppm and 17.8mHz/ppm rates, as obtained from numerical calculations and experiments, respectively. Besides, the peak shape and maximum intensity are preserved. Due to the linear shift of the resonance peak with respect to the carbon dioxide concentration, acoustic intensity at initial peak frequency can be utilized as an auxiliary means for concentrations up to 1000ppm. The proposed ring resonator can be adapted to a variety of acoustic devices such as liquid concentration sensors based on phononic crystals, surface acoustic wave sensors, and micromechanical resonators.
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    Ultrasonic Gas Sensing by Two-Dimensional Surface Phononic Crystal Ring Resonators
    (Amer Chemical Soc, 2019) Cicek, Ahmet; Trak, Digdem; Arslan, Yasin; Korozlu, Nurettin; Kaya, Olgun A.; Ulug, Bulent
    An acoustic ring resonator employing a two-dimensional surface phononic crystal is proposed for high-sensitivity detection in binary gas mixtures. Band analyses and frequency-domain simulations via the finite-element method reveal that a single band for spoof surface acoustic waves appears at ultrasonic frequencies around 58 kHz where modification of its dispersion due to varying gas composition results in a linear shift of the resonance frequency. The shift rate is -17.3 and 8.8 mHz/ppm for CO2 and CH4, respectively. The linear shift of resonance frequency is experimentally validated. In addition, the ring resonator can also be employed to track acoustic intensity variation with gas concentration, where exponentially decaying intensity for low concentrations leverages high-sensitivity operation.