scholarly journals Correlation-based Doppler-angle estimation with plane-wave excitation

2020 ◽  
Vol 19 ◽  
pp. 100315
Author(s):  
U-Wai Lok ◽  
Fang-Yu Lin ◽  
Chia-Lun Yeh ◽  
Pai-Chi Li
Keyword(s):  
Plane Wave ◽  
Wave Excitation ◽  
Angle Estimation ◽  
Doppler Angle

scholarly journals Computer Vision Approach for Ultrasound Doppler Angle Estimation

2008 ◽  
Vol 22 (6) ◽  
pp. 681-688 ◽  
Author(s):  
Ashraf A. Saad ◽  
Thanasis Loupas ◽  
Linda G. Shapiro
Keyword(s):  
Computer Vision ◽  
Angle Estimation ◽  
Ultrasound Doppler ◽  
Doppler Angle

Joint Range-Doppler-Angle Estimation for Intelligent Tracking of Moving Aerial Targets

2018 ◽  
Vol 5 (3) ◽  
pp. 1625-1636 ◽  
Author(s):  
Liangtian Wan ◽  
Xiangjie Kong ◽  
Feng Xia
Keyword(s):  
Angle Estimation ◽  
Doppler Angle ◽  
Joint Range ◽  
Intelligent Tracking

Efficient Plane Wave Excitation for 3-D Laguerre-Based FDTD Method

2014 ◽  
Vol 556-562 ◽  
pp. 4542-4546
Author(s):  
Zheng Chen ◽  
Yan Tao Duan ◽  
Ye Rong Zhang ◽  
Cheng Gao
Keyword(s):  
Plane Wave ◽  
Electric Fields ◽  
Laguerre Polynomials ◽  
Fdtd Method ◽  
Three Dimensional ◽  
Field Variable ◽  
Wave Excitation ◽  
Computationally Efficient ◽  
Scattering Problems ◽  
Scatter Field

In the three-dimensional (3-D) Laguerre-based finite-difference time-domain method, each electric field variable has the relationship with the adjacent twelve electric fields. This results in the tedious modification of field components adjacent to the total-field/scatter-field boundary in analyzing scattering problems. In addition, the plane wave excitation requires much time in evaluating the expansion coefficient of incident field which involves integral of the weighted Laguerre polynomials with respect to time. In this letter, the plane wave is introduced by defining a set of equivalent currents on a closed Huygen's surface and a computationally efficient one-dimensional auxiliary propagator is presented to speed up the plane wave excitation. Numerical results indicated that the proposed method is valid.

Doppler Angle Estimation of Pulsatile Flows Using AR Modeling

2002 ◽  
Vol 24 (2) ◽  
pp. 65-80 ◽  
Author(s):  
Chih-Kuang Yeh ◽  
Pai-Chi Li
Keyword(s):  
Real Time ◽  
Doppler Spectrum ◽  
Acquisition Time ◽  
Two Dimensional ◽  
Flow Measurements ◽  
Angle Estimation ◽  
Flow Angle ◽  
Doppler Angle ◽  
Wide Range ◽  
Pulsatile Flows

In quantitative ultrasonic flow measurements, the beam-to-flow angle (i.e., Doppler angle) is an important parameter. An autoregressive (AR) spectral analysis technique in combination with the Doppler spectrum broadening effect was previously proposed to estimate the Doppler angle. Since only a limited number of flow samples are used, real-time two-dimensional Doppler angle estimation is possible. The method was validated for laminar flows with constant velocities. In clinical applications, the flow pulsation needs to be considered. For pulsatile flows, the flow velocity is time-varying and the accuracy of Doppler angle estimation may be affected. In this paper, the AR method using only a limited number of flow samples was applied to Doppler angle estimation of pulsatile flows. The flow samples were properly selected to derive the AR coefficients and then more samples were extrapolated based on the AR model. The proposed method was verified by both simulations and in vitro experiments. A wide range of Doppler angles (from 30° to 78°) and different flow rates were considered. The experimental data for the Doppler angle showed that the AR method using eight flow samples had an average estimation error of 3.50° compared to an average error of 7.08° for the Fast Fourier Transform (FFT) method using 64 flow samples. Results indicated that the AR method not only provided accurate Doppler angle estimates, but also outperformed the conventional FFT method in pulsatile flows. This is because the short data acquisition time is less affected by the temporal velocity changes. It is concluded that real-time two-dimensional estimation of the Doppler angle is possible using the AR method in the presence of pulsatile flows. In addition, Doppler angle estimation with turbulent flows is also discussed. Results show that both the AR and FFT methods are not adequate due to the spectral broadening effects from the turbulence.

Analysis and applications of one-dimensional periodic dielectric gratings under plane wave excitation

2004 ◽  
Author(s):  
A. Coves ◽  
A. A. San Blas ◽  
B. Gimeno ◽  
Miguel V. Andres ◽  
Vincente E. Boria ◽  
...  
Keyword(s):  
Plane Wave ◽  
Wave Excitation ◽  
One Dimensional ◽  
Dielectric Gratings
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