WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394

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  • Conference Object
    Citation - Scopus: 7
    Design of Capacitive Micromachined Ultrasonic Transducers (Cmuts) on a Flexible Substrate for Intravascular Ultrasonography (Ivus) Applications
    (Institute of Electrical and Electronics Engineers Inc., 2017-05) Hah, Dooyoung; Je, Changhan; Lee, Sung Q.
    Effects of substrate bending to the characteristics of capacitive miniaturized ultrasonic transducers (CMUTs) on a flexible substrate are studied through finite element analysis (FEA) for the design purpose. The target application of the devices is intravascular ultrasonography (IVUS) where transducers are brought to the proximity of the imaging targets so that high resolution images can be obtained without much concern of signal attenuation. In order to eliminate mechanical rotation used in the conventional IVUS, the transducer array can be manufactured on a flexible substrate and to wrap it around a cylindrical frame. It can be anticipated that the characteristics of the transducers will be altered by such bending of the substrate through geometrical dimension changes and stress induced. Pull-in voltages and resonant frequencies of CMUTs were studied via FEA for various bending radii and membrane thicknesses. It was found that both pull-in voltages and resonant frequencies become smaller for the transducers on a bent substrate compared to the ones on a flat substrate. It was also found that pull-in voltages decrease as the substrate bending radius is reduced. © 2017 Elsevier B.V., All rights reserved.
  • Article
    Citation - WoS: 20
    Citation - Scopus: 21
    Application of the Collocation Method With B-Splines to the GEW Equation
    (Kent State University, 2017) Zeybek, Halil; Karakoc, S. Battal Gazi
    In this paper, the generalized equal width (GEW) wave equation is solved numerically by using a quintic B-spline collocation algorithm with two different linearization techniques. Also, a linear stability analysis of the numerical scheme based on the von Neumann method is investigated. The numerical algorithm is applied to three test problems consisting of a single solitary wave, the interaction of two solitary waves, and a Maxwellian initial condition. In order to determine the performance of the numerical method, we compute the error in the L-2- and L-infinity- norms and in the invariants I-1, I-2, and I-3 of the GEW equation. These calculations are compared with earlier studies. Afterwards, the motion of solitary waves according to different parameters is designed.
  • Conference Object
    An Fem Study of Die Attach Packaging Effect on Nanomechanical Si Optical Filters
    (Institute of Electrical and Electronics Engineers Inc., 2017-05) Seok, Seonho; Hah, Dooyoung
    This paper presents a finite element analysis of die attach packaging stress effect on emerging nanomechanical silicon optical filters. The proposed silicon optical filter is composed of Si waveguides and a microring resonator having a few hundred nm in thickness and a few tens of μm in length. Photonic integrated circuit is typically implemented by attaching a new component to a common ceramic interposer with other components. Such an attachment process would be a cause of unwanted performance deviation of MEMS or NEMS devices due to the packaging stress. Therefore, an FEM model has been used to evaluate deflection and stress of NEMS waveguides and microring resonators which are main elements for the proposed optical filter. © 2017 Elsevier B.V., All rights reserved.