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https://www.readbyqxmd.com/read/28432914/adaptive-optimization-of-ultrasound-beamforming-sound-velocity-using-sub-aperture-differential-phase-gradient
#1
Che-Chou Shen, Hsiao-Chi Yang
Ultrasound array imaging systems rely on a presumed beamforming sound velocity to calculate the time compensation of each element for receive focusing. The mismatch between the tissue sound velocity and the beamforming sound velocity can degrade the focusing quality due to loss of phase coherence. Since the tissue sound velocity cannot be known in prior, an adaptive optimization of beamforming sound velocity is required to improve the image quality. Differential phase gradient of channel data is proposed to estimate the optimal sound velocity for beamforming...
April 12, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28394290/combining-dcqgmp-based-sparse-decomposition-and-mpdr-beamformer-for-multi-type-interferences-mitigation-for-gnss-receivers
#2
Qiang Guo, Liangang Qi
In the coexistence of multiple types of interfering signals, the performance of interference suppression methods based on time and frequency domains is degraded seriously, and the technique using an antenna array requires a large enough size and huge hardware costs. To combat multi-type interferences better for GNSS receivers, this paper proposes a cascaded multi-type interferences mitigation method combining improved double chain quantum genetic matching pursuit (DCQGMP)-based sparse decomposition and an MPDR beamformer...
April 10, 2017: Sensors
https://www.readbyqxmd.com/read/28391187/double-stage-delay-multiply-and-sum-beamforming-algorithm-application-to-linear-array-photoacoustic-imaging
#3
Moein Mozaffarzadeh, Ali Mahloojifar, Mahdi Orooji, Saba Adabi, Mohammadreza Nasiriavanaki
Photoacoustic imaging (PAI) is an emerging medical imaging modality capable of providing high spatial resolution of Ultrasound (US) imaging and high contrast of optical imaging. Delay-and-Sum (DAS) is the most common beamforming algorithm in PAI. However, using DAS beamformer leads to low resolution images and considerable contribution of offaxis signals. A new paradigm namely Delay-Multiply-and-Sum (DMAS), which was originally used as a reconstruction algorithm in confocal microwave imaging, was introduced to overcome the challenges in DAS...
April 5, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28378012/computational-acoustic-beamforming-for-noise-source-identification-for-small-wind-turbines
#4
Ping Ma, Fue-Sang Lien, Eugene Yee
This paper develops a computational acoustic beamforming (CAB) methodology for identification of sources of small wind turbine noise. This methodology is validated using the case of the NACA 0012 airfoil trailing edge noise. For this validation case, the predicted acoustic maps were in excellent conformance with the results of the measurements obtained from the acoustic beamforming experiment. Following this validation study, the CAB methodology was applied to the identification of noise sources generated by a commercial small wind turbine...
2017: International Scholarly Research Notices
https://www.readbyqxmd.com/read/28372122/coherence-factor-and-wiener-postfilter-in-synthetic-aperture-ultrasound-imaging
#5
Jinxin Zhao, Yuanyuan Wang, Wei Guo, Jinhua Yu
The coherence factor (CF) and Wiener postfilter methods have been proposed as effective approaches for reducing the output noise of the delay-and-sum (DAS) beamformer in ultrasound imaging. The theoretical framework between them was also established. However, past researches about the CF and Wiener postfilter methods mainly focused on the summation of an array signal. This paper analyzes the CF and Wiener postfilter in the synthetic aperture (SA) imaging mode, where two-dimensional echo data are recorded. Different CF definitions in the SA imaging are first given and the corresponding Wiener postfilter methods are then proposed, including a Wiener postfilter especially for the SA imaging, named as WienerSA...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28372093/generalized-sidelobe-canceller-beamforming-method-for-ultrasound-imaging
#6
Ping Wang, Na Li, Han-Wu Luo, Yong-Kun Zhu, Shi-Gang Cui
A modified generalized sidelobe canceller (IGSC) algorithm is proposed to enhance the resolution and robustness against the noise of the traditional generalized sidelobe canceller (GSC) and coherence factor combined method (GSC-CF). In the GSC algorithm, weighting vector is divided into adaptive and non-adaptive parts, while the non-adaptive part does not block all the desired signal. A modified steer vector of the IGSC algorithm is generated by the projection of the non-adaptive vector on the signal space constructed by the covariance matrix of received data...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28351747/improved-contrast-for-high-frame-rate-imaging-using-coherent-compounding-combined-with-spatial-matched-filtering
#7
Yang Lou, Jesse T Yen
The concept of high frame rate ultrasound imaging (typically greater than 1000 frames per second) has inspired new fields of clinical applications for ultrasound imaging such as fast cardiovascular imaging, fast Doppler imaging and real-time 3D imaging. Coherent plane-wave compounding is a promising beamforming technique to achieve high frame rate imaging. By combining echoes from plane waves with different angles, dynamic transmit focusing is efficiently accomplished at all points in the image field. Meanwhile, the image frame rate can still be kept at a high level...
March 20, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28327467/automated-detection-of-epileptic-ripples-in-meg-using-beamformer-based-virtual-sensors
#8
Carolina Migliorelli, Joan Alonso, Sergio Romero, Rafal Nowak, Antonio Russi, Miguel Mananas
OBJECTIVE: In epilepsy, high-frequency oscillations (HFOs) are considered events highly linked to the seizure onset zone (SOZ). The detection of HFOs in noninvasive signals such as scalp EEG and MEG is still a challenging task. The aim of this study was to automatize the detection of ripples in MEG signals reducing the high-frequency noise using beamformer-based virtual sensors (VS) and applying an automatic procedure exploring the time-frequency content of the detected events. APPROACH: 200 seconds of MEG signals and simultaneous iEEG were selected in nine patients with refractory epilepsy...
March 22, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28320658/compressed-sensing-based-synthetic-transmit-aperture-imaging-validation-in-a-convex-array-configuration
#9
Jing Liu, Qiong He, Jianwen Luo
According to the linear acoustic theory, the channel data of a plane wave emitted by a linear array is a linear combination of the full dataset of synthetic transmit aperture (STA). Combining this relationship with compressed sensing (CS), a novel CS based ultrasound beamforming strategy, named compressed sensing based synthetic transmit aperture (CS-STA), was previously proposed to increase the frame rate of ultrasound imaging without sacrificing the image quality for a linear array. In this paper, assuming linear transfer function of pulse-echo ultrasound system, we derived and applied the theory of CS-STA for a slightly curved array and validated CS-STA in a convex array configuration...
March 14, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28318887/multi-focus-beamforming-for-thermal-strain-imaging-using-a-single-ultrasound-linear-array-transducer
#10
Man M Nguyen, Xuan Ding, Steven A Leers, Kang Kim
Ultrasound-induced thermal strain imaging (TSI) has been used successfully to identify lipid- and water-based tissues in atherosclerotic plaques in some research settings. However, TSI faces several challenges to be realized in clinics. These challenges include motion artifacts and displacement tracking accuracy, as well as limited heating capability, which contributes to low thermal strain signal-to-noise ratio, and a limited field of view. Our goal was to address the challenge in heating tissue in TSI. Current TSI systems use separate heating and imaging transducers, which require physical alignment of the heating and imaging beams and result in a bulky setup that limits in vivo operation...
March 15, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/28282862/an-assessment-of-iterative-reconstruction-methods-for-sparse-ultrasound-imaging
#11
Solivan A Valente, Marcelo V W Zibetti, Daniel R Pipa, Joaquim M Maia, Fabio K Schneider
Ultrasonic image reconstruction using inverse problems has recently appeared as an alternative to enhance ultrasound imaging over beamforming methods. This approach depends on the accuracy of the acquisition model used to represent transducers, reflectivity, and medium physics. Iterative methods, well known in general sparse signal reconstruction, are also suited for imaging. In this paper, a discrete acquisition model is assessed by solving a linear system of equations by an ℓ 1 -regularized least-squares minimization, where the solution sparsity may be adjusted as desired...
March 8, 2017: Sensors
https://www.readbyqxmd.com/read/28268996/effects-of-phase-aberration-correction-methods-on-the-minimum-variance-beamformer
#12
Gustavo R Chau, Jeremy J Dahl, Roberto J Lavarello
The minimum variance (MV) beamformer is a method that has the potential to enhance the resolution and contrast of ultrasound images. However, it suffers from sensitivity to speed of sound errors and aberration. Although there have been several studies on the application of phase aberration correction (PAC) methods to conventional delay-and-sum (DAS) beamforming, the benefits of PAC methods in mitigating the effects of phase aberration in MV beamformed images are not well understood. A study of this type would be helpful in designing a robust beamformer based on PAC knowledge present in the literature...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28253687/application-of-acoustic-imaging-techniques-on-snowmobile-pass-by-noise
#13
Thomas Padois, Alain Berry
Snowmobile manufacturers invest important efforts to reduce the noise emission of their products. The noise sources of snowmobiles are multiple and closely spaced, leading to difficult source separation in practice. In this study, source imaging results for snowmobile pass-by noise are discussed. The experiments involve a 193-microphone Underbrink array, with synchronization of acoustic with video data provided by a high-speed camera. Both conventional beamforming and Clean-SC deconvolution are implemented to provide noise source maps of the snowmobile...
February 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28253650/blind-deconvolution-of-shipping-sources-in-an-ocean-waveguide
#14
Sung-Hoon Byun, Christopher M A Verlinden, Karim G Sabra
This paper investigates the applicability of a ray-based blind deconvolution (RBD) method for underwater acoustic sources of opportunity such as ships recorded on a receiver array. The RBD relies on first estimating the unknown phase of the random source by beamforming along a well-resolved ray path, and then matched-filtering each received signal using the knowledge of this random phase to estimate the full channel impulse responses (CIRs) between the unknown source and the array elements (up to an arbitrary time-shift) as well as recovering the radiated signal by the random source...
February 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28248655/4d-in-vivo-ultrafast-ultrasound-imaging-using-a-row-column-addressed-matrix-and-coherently-compounded-orthogonal-plane-waves
#15
Martin Flesch, Mathieu Pernot, Jean Provost, Guillaume Ferin, An Nguyen-Dinh, Mickael Tanter, Thomas Deffieux
4D ultrafast ultrasound imaging was recently shown using a 2D matrix (i.e., fully populated) connected to a 1024-channel ultrafast ultrasound scanner. In this study, we investigate the Row-Column Addressing (RCA) matrix approach, which allows a reduction of independent channels from N x N to N + N, with a dedicated beamforming strategy for ultrafast ultrasound imaging based on the coherent compounding of Orthogonal Plane Wave (OPW). OPW is based on coherent compounding of plane wave transmissions in one direction with receive beamforming along the orthogonal direction and its orthogonal companion sequence...
March 1, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28227206/effects-of-phase-aberration-correction-methods-on-the-minimum-variance-beamformer
#16
Gustavo R Chau, Jeremy J Dahl, Roberto J Lavarello, Gustavo R Chau, Jeremy J Dahl, Roberto J Lavarello, Gustavo R Chau, Roberto J Lavarello
The minimum variance (MV) beamformer is a method that has the potential to enhance the resolution and contrast of ultrasound images. However, it suffers from sensitivity to speed of sound errors and aberration. Although there have been several studies on the application of phase aberration correction (PAC) methods to conventional delay-and-sum (DAS) beamforming, the benefits of PAC methods in mitigating the effects of phase aberration in MV beamformed images are not well understood. A study of this type would be helpful in designing a robust beamformer based on PAC knowledge present in the literature...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28147604/large-region-acoustic-source-mapping-using-a-movable-array-and-sparse-covariance-fitting
#17
Shengkui Zhao, Cagdas Tuna, Thi Ngoc Tho Nguyen, Douglas L Jones
Large-region acoustic source mapping is important for city-scale noise monitoring. Approaches using a single-position measurement scheme to scan large regions using small arrays cannot provide clean acoustic source maps, while deploying large arrays spanning the entire region of interest is prohibitively expensive. A multiple-position measurement scheme is applied to scan large regions at multiple spatial positions using a movable array of small size. Based on the multiple-position measurement scheme, a sparse-constrained multiple-position vectorized covariance matrix fitting approach is presented...
January 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28147570/adaptive-and-compressive-matched-field-processing
#18
Kay L Gemba, William S Hodgkiss, Peter Gerstoft
Matched field processing is a generalized beamforming method that matches received array data to a dictionary of replica vectors in order to locate one or more sources. Its solution set is sparse since there are considerably fewer sources than replicas. Using compressive sensing (CS) implemented using basis pursuit, the matched field problem is reformulated as an underdetermined, convex optimization problem. CS estimates the unknown source amplitudes using the replica dictionary to best explain the data, subject to a row-sparsity constraint...
January 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28114609/the-effects-of-directional-processing-on-objective-and-subjective-listening-effort
#19
Erin M Picou, Travis M Moore, Todd A Ricketts
Purpose: The purposes of this investigation were (a) to evaluate the effects of hearing aid directional processing on subjective and objective listening effort and (b) to investigate the potential relationships between subjective and objective measures of effort. Method: Sixteen adults with mild to severe hearing loss were tested with study hearing aids programmed with 3 settings: omnidirectional, fixed directional, and bilateral beamformer. A dual-task paradigm and subjective ratings were used to assess objective and subjective listening effort, respectively, in 2 signal-to-noise ratios...
January 1, 2017: Journal of Speech, Language, and Hearing Research: JSLHR
https://www.readbyqxmd.com/read/28113662/beamforming-through-regularized-inverse-problems-in-ultrasound-medical-imaging
#20
Teodora Szasz, Adrian Basarab, Denis Kouame
Beamforming in ultrasound imaging has significant impact on the quality of the final image, controlling its resolution and contrast. Despite its low spatial resolution and contrast, delay-and-sum is still extensively used nowadays in clinical applications, due to its real-time capabilities. The most common alternatives are minimum variance method and its variants, which overcome the drawbacks of delay-and-sum, at the cost of higher computational complexity that limits its utilization in real-time applications...
September 13, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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