scholarly journals Two-Dimensional Spatial Coherence for Ultrasonic DMAS Beamforming in Multi-Angle Plane-Wave Imaging

2019 ◽  
Vol 9 (19) ◽  
pp. 3973 ◽  
Author(s):  
Che-Chou Shen ◽  
Pei-Ying Hsieh
Keyword(s):  
Image Quality ◽  
Plane Wave ◽  
Spatial Coherence ◽  
P Value ◽  
Two Dimensional ◽  
One Dimensional ◽  
Wave Imaging ◽  
Artifact Suppression ◽  
Simulation Results ◽  
Acquisition Delay

Ultrasonic multi-angle plane-wave (PW) coherent compounding relies on delay-and-sum (DAS) beamforming of two-dimensional (2D) echo matrix in both the dimensions PW transmit angle and receiving channel to construct each image pixel. Due to the characteristics of DAS beamforming, PW coherent compounding may suffer from high image clutter when the number of transmit angles is kept low for ultrafast image acquisition. Delay-multiply-and-sum (DMAS) beamforming exploits the spatial coherence of the receiving aperture to suppress clutter interference. Previous attempts to introduce DMAS beamforming into multi-angle PW imaging has been reported but only in either dimension of the 2D echo matrix. In this study, a novel DMAS operation is proposed to extract the 2D spatial coherence of echo matrix for further improvement of image quality. The proposed 2D-DMAS method relies on a flexibly tunable p value to manipulate the signal coherence in the beamforming output. For p = 2.0 as an example, simulation results indicate that 2D-DMAS outperforms other one-dimensional DMAS methods by at least 9.3 dB in terms of ghost-artifact suppression. Experimental results also show that 2D-DMAS provides the highest improvement in lateral resolution by 32% and in image contrast by 15.6 dB relative to conventional 2D-DAS beamforming. Nonetheless, since 2D-DMAS emphasizes signal coherence more than its one-dimensional DMAS counterparts, it suffers from the most elevated speckle variation and the granular pattern in the tissue background.

scholarly journals DMAS Beamforming with Complementary Subset Transmit for Ultrasound Coherence-Based Power Doppler Detection in Multi-Angle Plane-Wave Imaging

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4856
Author(s):  
Che-Chou Shen ◽  
Yen-Chen Chu
Keyword(s):  
Plane Wave ◽  
Power Doppler ◽  
P Value ◽  
Low Resolution ◽  
Ensemble Averaging ◽  
Stationary Tissue ◽  
Wave Imaging ◽  
Acquisition Delay ◽  
Complementary Subset ◽  
Low Resolution Images

Conventional ultrasonic coherent plane-wave (PW) compounding corresponds to Delay-and-Sum (DAS) beamforming of low-resolution images from distinct PW transmit angles. Nonetheless, the trade-off between the level of clutter artifacts and the number of PW transmit angle may compromise the image quality in ultrafast acquisition. Delay-Multiply-and-Sum (DMAS) beamforming in the dimension of PW transmit angle is capable of suppressing clutter interference and is readily compatible with the conventional method. In DMAS, a tunable p value is used to modulate the signal coherence estimated from the low-resolution images to produce the final high-resolution output and does not require huge memory allocation to record all the received channel data in multi-angle PW imaging. In this study, DMAS beamforming is used to construct a novel coherence-based power Doppler detection together with the complementary subset transmit (CST) technique to further reduce the noise level. For p = 2.0 as an example, simulation results indicate that the DMAS beamforming alone can improve the Doppler SNR by 8.2 dB compared to DAS counterpart. Another 6-dB increase in Doppler SNR can be further obtained when the CST technique is combined with DMAS beamforming with sufficient ensemble averaging. The CST technique can also be performed with DAS beamforming, though the improvement in Doppler SNR and CNR is relatively minor. Experimental results also agree with the simulations. Nonetheless, since the DMAS beamforming involves multiplicative operation, clutter filtering in the ensemble direction has to be performed on the low-resolution images before DMAS to remove the stationary tissue without coupling from the flow signal.

scholarly journals A United Sign Coherence Factor Beamformer for Coherent Plane-Wave Compounding with Improved Contrast

2020 ◽  
Vol 10 (7) ◽  
pp. 2250 ◽  
Author(s):  
Chen Yang ◽  
Yang Jiao ◽  
Tingyi Jiang ◽  
Yiwen Xu ◽  
Yaoyao Cui
Keyword(s):  
Image Quality ◽  
Plane Wave ◽  
Contrast Ratio ◽  
Spatial Coherence ◽  
Frame Rate ◽  
In Vivo Studies ◽  
Angular Dimension ◽  
One Dimensional ◽  
Coherence Factor

In this study, we present a united sign coherence factor beamformer for coherent plane-wave compounding (CPWC). CPWC is capable of reaching an image quality comparable to the conventional B-mode with a much higher frame rate. Conventional coherence factor (CF) based beamformers for CPWC are based on one-dimensional (1D) frameworks, either in the spatial coherence dimension or angular coherence dimension. Both 1D frameworks do not take into account the coherence information of the dimensions of each other. In order to take full advantage of the radio-frequency (RF) data, this paper proposes a united framework containing both spatial and angular information for CPWC. A united sign coherence factor beamformer (uSCF), which combines the conventional sign coherence factor (SCF) and the united framework, is introduced in the paper as well. The proposed beamformer is compared with the conventional 1D SCF beamformers (spatial and angular dimension beamformers) using simulation, phantom and in vivo studies. In the in vivo images, the proposed method improves the contrast ratio (CR) and generalized contrast-to-noise ratio (gCNR) by 197% and 20% over CPWC. Compared with other 1D methods, uSCF also shows an improved contrast and lateral resolution on all datasets.

scholarly journals Plane Wave Imaging through Interfaces

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 4967
Author(s):  
Guillermo Cosarinsky ◽  
Jorge F. Cruza ◽  
Jorge Camacho
Keyword(s):  
Image Quality ◽  
Plane Wave ◽  
Phased Array ◽  
Mathematical Formulation ◽  
Non Destructive Testing ◽  
Arbitrary Geometry ◽  
Destructive Testing ◽  
Wave Imaging ◽  
Imaging Strategy ◽  
Non Destructive

Plane Wave Imaging (PWI) has been recently proposed for fast ultrasound inspections in the Non-Destructive-Testing (NDT) field. By using a single (or a reduced number) of plane wave emissions and parallel beamforming in reception, frame rates of hundreds to thousands of images per second can be achieved without significant image quality losses with regard to the Total Focusing Method (TFM) or Phased Array (PA). This work addresses the problem of applying PWI in the presence of arbitrarily shaped interfaces, which is a common problem in NDT. First, the mathematical formulation for generating a plane wave inside a component of arbitrary geometry is given, and the characteristics of the resultant acoustic field are analyzed by simulation, showing plane wavefronts with non-uniform amplitude. Then, an imaging strategy is proposed, accounting for this amplitude effect. Finally, the proposed method is experimentally validated, and its application limits are discussed.

Person Localization System Using Privacy-Preserving Sensor

2011 ◽  
Vol 103 ◽  
pp. 622-627 ◽  
Author(s):  
Shota Nakashima ◽  
Hui Min Lu ◽  
Kohei Miyata ◽  
Yuhki Kitazono ◽  
Serikawa Seiichi
Keyword(s):  
Low Cost ◽  
Video Camera ◽  
Brightness Distribution ◽  
Privacy Preserving ◽  
Two Dimensional ◽  
Texture Image ◽  
Localization System ◽  
One Dimensional ◽  
Two Dimensional Image ◽  
Simulation Results

A privacy-preserving sensor for person localization has been developed. In theory, the sensor can be constructed with a line sensor and cylindrical lens because only a one-dimensional brightness distribution is needed. However, a line sensor is expensive. In contrast, CMOS area sensors are low cost and are increasing in sensitivity according to recent rapid advancement in the technology. Therefore, we covered the CMOS area sensor physically so that it behaved as a line sensor, we substituted CMOS sensors for the line sensors in practice. The proposed sensor obtains a one-dimensional horizontal brightness distribution that is approximately equal to the integration value of each vertical pixel line of the two-dimensional image. It is impossible to restore the two-dimensional detail texture image from one-dimensional brightness distribution, although it obtains enough information to detect a person’s position and movement status. Thus, the privacy is protected. Moreover, the appearance of the proposed sensor is very different from the conventional video camera, so the psychological resistance of having a picture taken is reduced. In this work, we made the privacy preserving sensor practically, and verified whether a person’s state was able to be detected. The simulation results show that the proposed sensor can detect a present person’s state responsively without violating privacy.

scholarly journals Reduced-Dimension Noncircular-Capon Algorithm for DOA Estimation of Noncircular Signals

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Weihua Lv ◽  
Huapu Sun ◽  
Xiaofei Zhang ◽  
Dazhuan Xu
Keyword(s):  
Computational Cost ◽  
Doa Estimation ◽  
Two Dimensional ◽  
Angle Estimation ◽  
One Dimensional ◽  
Reduced Dimension ◽  
Noncircular Signals ◽  
Simulation Results ◽  
High Computational Cost ◽  
Better Than

The problem of the direction of arrival (DOA) estimation for the noncircular (NC) signals, which have been widely used in communications, is investigated. A reduced-dimension NC-Capon algorithm is proposed hereby for the DOA estimation of noncircular signals. The proposed algorithm, which only requires one-dimensional search, can avoid the high computational cost within the two-dimensional NC-Capon algorithm. The angle estimation performance of the proposed algorithm is much better than that of the conventional Capon algorithm and very close to that of the two-dimensional NC-Capon algorithm, which has a much higher complexity than the proposed algorithm. Furthermore, the proposed algorithm can be applied to arbitrary arrays and works well without estimating the noncircular phases. The simulation results verify the effectiveness and improvement of the proposed algorithm.

scholarly journals Two-Dimensional AOA Estimation Based on a Constant Modulus Algorithm

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Saleh O. Al-Jazzar ◽  
Zoubir Hamici ◽  
Sami Aldalahmeh
Keyword(s):  
Two Dimensional ◽  
Constant Modulus ◽  
Constant Modulus Algorithm ◽  
Angle Of Arrival ◽  
One Dimensional ◽  
Simulation Results ◽  
The One ◽  
Different Sources

We propose a two-dimensional (2D) angle of arrival (AOA) estimator using the algebraic constant modulus algorithm (ACMA). This algorithm was originally introduced to estimate the one-dimensional (1D) AOA. An extension to estimate and automatically pair the elevation and azimuth angles for different sources is derived and proved in this paper. The ACMA method factorises a matrix into two different matrices; one is of constant modulus and contains the azimuth AOA information; however the second was previously ignored. In this paper we will prove that this second matrix contains the elevation AOA information. Thus, 2D AOA estimation is proved possible using the ACMA method. Simulation results are presented to illustrate the proposed method’s performances under different conditions.

scholarly journals Efficient Two-Dimensional Blocked Element Compensation

1994 ◽  
Vol 16 (3) ◽  
pp. 164-175 ◽  
Author(s):  
Pai-Chi Li ◽  
M. O'Donnell
Keyword(s):  
Image Quality ◽  
Ultrasound Image ◽  
The Body ◽  
Two Dimensional ◽  
Hardware Complexity ◽  
Computationally Efficient ◽  
One Dimensional ◽  
Spread Function ◽  
Computationally Efficient Algorithms ◽  
Beam Characteristics

Very large, two-dimensional, anisotropic arrays have been proposed to improve ultrasound image quality. Due to noncontiguous acoustic windows into the body, however, a significant portion of such an aperture may be blocked. Blocked elements result in high sidelobes in the point spread function, degrading image quality. To compensate for this, an object dependent method using multiple receive beams has been recently proposed. This method is effective in removing undesired sidelobes. However, previous results were for one-dimensional arrays where only lateral beams were used for estimation. With two-dimensional arrays, the distribution of blocked elements can change beam characteristics, both laterally and elevationally. In other words, receive beams must be formed in both directions for better performance. Although straightforward in principle, extension of the algorithm from one dimension to two increases computational complexity dramatically. Furthermore, the restricted elevational steering capability of anisotropic arrays also limits performance. In this paper, several computationally efficient algorithms for two-dimensional blocked element compensation are proposed and evaluated. It is shown that undesired sidelobes can be effectively removed using only a limited number of receive beams. Image quality can therefore be restored in the presence of blocked elements without significantly increasing hardware complexity.

Estimation of a Moving Vehicle’s Position and Orientation Using Probabilistic Data Association

2005 ◽  
Author(s):  
Yu Lei ◽  
Guang Lu
Keyword(s):  
Laser Scanning ◽  
Data Association ◽  
Separation Distance ◽  
Vehicle Tracking ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
One Dimensional ◽  
Vehicle Simulation ◽  
Simulation Results ◽  
Position And Orientation

This paper presents a computationally efficient algorithm for real-time vehicle tracking, by detecting the two taillights using a laser scanning radar (LIDAR) sensor. It is assumed that the two targets are constrained by fixed known separation distance 2l. To reject clutter, a Probability Data Association (PDA) based algorithm is proposed. The algorithm first predicts the orientation of the vehicle and the position of one of the two targets. Then it uses a two-dimensional PDA filter to estimate the position of this target. All the measurements whose distance from the estimated target is close to 2l are converted into orientation angles. This is followed by a one-dimensional PDA filter, which probabilistically combines calculated angles to estimate the orientation of the vehicle. Simulation results show significant improvement by this algorithm over other methods, in terms of orientation tracking.

The Method of Two-Dimensional Stretching to Reduce Residual Stress in Quenched Thin-Walled Aluminum Alloy

2015 ◽  
Vol 1095 ◽  
pp. 523-526
Author(s):  
Kun Qi Wang ◽  
Wei Zheng ◽  
Dan Dan Na
Keyword(s):  
Thermal Analysis ◽  
Residual Stress ◽  
Aluminum Alloy ◽  
Steady State ◽  
Two Dimensional ◽  
One Dimensional ◽  
Thin Walled ◽  
Simulation Results ◽  
Transient Thermal ◽  
Better Than

This study aims to reduce the residual stress of quenched thin-walled aluminum alloy. The method of two-dimensional stretching was proposed to further reduce the residual stress in the alloy. The steady-state and transient thermal analysis were used in ANSYS workbench15.0. Static structural was used to simulate one-dimensional and two-dimensional stretching. The simulation results show that two-dimensional stretching method is better than one-dimensional stretching, and it can eliminate the residual stress up to 92.6% when the amount of stretching in length and width is controlled in 2.5%.

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