scholarly journals A Computationally Efficient Mean Sound Speed Estimation Method Based on an Evaluation of Focusing Quality for Medical Ultrasound Imaging

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1368 ◽  
Author(s):  
Lee ◽  
Yoo ◽  
Yoon ◽  
Song
Keyword(s):  
Image Quality ◽  
Sound Speed ◽  
Soft Tissues ◽  
Low Cost ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Speed Estimation ◽  
Sound Speeds ◽  
Hardware Resource

Generally, ultrasound receive beamformers calculate the focusing time delays of fixed sound speeds in human tissue (e.g., 1540 m/s). However, phase distortions occur due to variations of sound speeds in soft tissues, resulting in degradation of image quality. Thus, an optimal estimation of sound speed is required in order to improve image quality. Implementation of real-time sound speed estimation is challenging due to high computational and hardware complexities. In this paper, an optimal sound speed estimation method with a low-cost hardware resource is presented. In the proposed method, the optimal mean sound speed is determined by measuring the amplitude variance of pre-beamformed radio-frequency (RF) data. The proposed method was evaluated with phantom and in vivo experiments, and implemented on Virtex-4 with Xilinx ISE 12.4 using VHDL. Experiment results indicate that the proposed method could estimate the mean optimal sound speed and enhance spatial resolution with a negligible increase in the hardware resource usage.

scholarly journals Ultrasonic fat fraction quantification using in vivo adaptive sound speed estimation

2018 ◽  
Vol 63 (21) ◽  
pp. 215013 ◽  
Author(s):  
Marion Imbault ◽  
Marco Dioguardi Burgio ◽  
Alex Faccinetto ◽  
Maxime Ronot ◽  
Hanna Bendjador ◽  
...  
Keyword(s):  
Sound Speed ◽  
Speed Estimation ◽  
Fat Fraction

An evaluation of an in vivo local sound speed estimation technique by the crossed beam method

1990 ◽  
Vol 16 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Masafumi Kondo ◽  
Kinya Takamizawa ◽  
Makoto Hirama ◽  
Kiyoshi Okazaki ◽  
Kazuhiro Iinuma ◽  
...  
Keyword(s):  
Sound Speed ◽  
Speed Estimation ◽  
Estimation Technique ◽  
Beam Method ◽  
Local Sound

scholarly journals A New In-Flight Alignment Method with an Application to the Low-Cost SINS/GPS Integrated Navigation System

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 512 ◽  
Author(s):  
Zhenglong Lu ◽  
Jie Li ◽  
Xi Zhang ◽  
Kaiqiang Feng ◽  
Xiaokai Wei ◽  
...  
Keyword(s):  
Navigation System ◽  
Gradient Descent ◽  
Low Cost ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Descent Method ◽  
Gradient Descent Method ◽  
Integrated Navigation ◽  
Integration Interval ◽  
Integrated Navigation System

The optimization-based alignment (OBA) methods, which are implemented by the optimal attitude estimation using vector observations—also called double-vectors—have proven to be effective at solving the in-flight alignment (IFA) problem. However, the traditional OBA methods are not applicable for the low-cost strap-down inertial navigation system (SINS) since the error of double-vectors will be accumulated over time due to the substantial drift of micro-electronic- mechanical system (MEMS) gyroscope. Moreover, the existing optimal estimation method is subject to a large computation burden, which results in a low alignment speed. To address these issues, in this article we propose a new fast IFA method based on modified double-vectors construction and the gradient descent method. To be specific, the modified construction method is implemented by reducing the integration interval and identifying the gyroscope bias during the construction procedure, which improves the accuracy of double-vectors and IFA; the gradient descent scheme is adopted to estimate the optimal attitude of alignment without complex matrix operation, which results in the improvement of alignment speed. The effect of different sizes of mini-batch on the performance of the gradient descent method is also discussed. Extensive simulations and vehicle experiments demonstrate that the proposed method has better accuracy and faster alignment speed than the related traditional methods for the low-cost SINS/global positioning system (GPS) integrated navigation system

Comparison of EMG-based and Accelerometer-based Speed Estimation Methods in Pedestrian Dead Reckoning

2011 ◽  
Vol 64 (2) ◽  
pp. 265-280 ◽  
Author(s):  
Wei Chen ◽  
Ruizhi Chen ◽  
Xiang Chen ◽  
Xu Zhang ◽  
Yuwei Chen ◽  
...  
Keyword(s):  
Low Cost ◽  
Estimation Method ◽  
Dead Reckoning ◽  
Field Tests ◽  
Human Locomotion ◽  
Estimation Methods ◽  
Speed Estimation ◽  
Navigation Systems ◽  
Emg Signal ◽  
Pedestrian Dead Reckoning

In low-cost self-contained pedestrian navigation systems, traditional Pedestrian Dead Reckoning (PDR) solutions utilize accelerometers to derive the speed as well as the distance travelled, and obtain the walking heading from magnetic compasses or gyros. However, these measurements are sensitive to instrument errors and disturbances from ambient environment. To be totally different from these signals in nature, the electromyography (EMG) signal is a typical kind of biomedical signal that measures electrical potentials generated by muscle contractions from the human body. This kind of signal would reflect muscle activities during human locomotion, so that it can not only be used for speed estimation, but also disclose the azimuth information from the contractions of lumbar muscles when changing the direction of walking. Therefore, investigating how to utilize the EMG signal for PDR is interesting and promising. In this paper, a novel EMG-based speed estimation method is presented, including setup of the EMG equipment, pre-processing procedure, stride detection and stride length estimation. Furthermore, this method suggested is compared with the traditional one based on accelerometers by means of several field tests. The results demonstrate that the EMG-based method is effective and its performance in PDR can be comparable to that of the accelerometer-based method.

An efficient sound speed estimation method to enhance image resolution in ultrasound imaging

Ultrasonics ◽  
2009 ◽  
Vol 49 (8) ◽  
pp. 774-778 ◽  
Author(s):  
M.H. Cho ◽  
L.H. Kang ◽  
J.S. Kim ◽  
S.Y. Lee
Keyword(s):  
Ultrasound Imaging ◽  
Sound Speed ◽  
Estimation Method ◽  
Image Resolution ◽  
Speed Estimation

A technique for protecting delicate specimens during processing

1989 ◽  
Vol 47 ◽  
pp. 982-983
Author(s):  
R.J. Mount ◽  
R.V. Harrison
Keyword(s):  
Basilar Membrane ◽  
Low Cost ◽  
Organ Of Corti ◽  
Region Of Interest ◽  
Sensory Epithelium ◽  
Physical Damage ◽  
Air Drying ◽  
Specimen Handling ◽  
Two Component

The sensory end organ of the ear, the organ of Corti, rests on a thin basilar membrane which lies between the bone of the central modiolus and the bony wall of the cochlea. In vivo, the organ of Corti is protected by the bony wall which totally surrounds it. In order to examine the sensory epithelium by scanning electron microscopy it is necessary to dissect away the protective bone and expose the region of interest (Fig. 1). This leaves the fragile organ of Corti susceptible to physical damage during subsequent handling. In our laboratory cochlear specimens, after dissection, are routinely prepared by the O-T- O-T-O technique, critical point dried and then lightly sputter coated with gold. This processing involves considerable specimen handling including several hours on a rotator during which the organ of Corti is at risk of being physically damaged. The following procedure uses low cost, readily available materials to hold the specimen during processing ,preventing physical damage while allowing an unhindered exchange of fluids.Following fixation, the cochlea is dehydrated to 70% ethanol then dissected under ethanol to prevent air drying. The holder is prepared by punching a hole in the flexible snap cap of a Wheaton vial with a paper hole punch. A small amount of two component epoxy putty is well mixed then pushed through the hole in the cap. The putty on the inner cap is formed into a “cup” to hold the specimen (Fig. 2), the putty on the outside is smoothed into a “button” to give good attachment even when the cap is flexed during handling (Fig. 3). The cap is submerged in the 70% ethanol, the bone at the base of the cochlea is seated into the cup and the sides of the cup squeezed with forceps to grip it (Fig.4). Several types of epoxy putty have been tried, most are either soluble in ethanol to some degree or do not set in ethanol. The only putty we find successful is “DUROtm MASTERMENDtm Epoxy Extra Strength Ribbon” (Loctite Corp., Cleveland, Ohio), this is a blue and yellow ribbon which is kneaded to form a green putty, it is available at many hardware stores.

Biological and biomedical applications of collagenous biomaterials

1990 ◽  
Vol 48 (3) ◽  
pp. 856-857
Author(s):  
Yasushi P. Kato ◽  
Michael G. Dunn ◽  
Frederick H. Silver ◽  
Arthur J. Wasserman
Keyword(s):  
Biomedical Applications ◽  
Soft Tissues ◽  
Collagen Fibers ◽  
Bone Collagen ◽  
Cover Slip ◽  
Fibroblast Migration ◽  
Cellular Expression ◽  
Defect Repair

Collagenous biomaterials have been used for growing cells in vitro as well as for augmentation and replacement of hard and soft tissues. The substratum used for culturing cells is implicated in the modulation of phenotypic cellular expression, cellular orientation and adhesion. Collagen may have a strong influence on these cellular parameters when used as a substrate in vitro. Clinically, collagen has many applications to wound healing including, skin and bone substitution, tendon, ligament, and nerve replacement. In this report we demonstrate two uses of collagen. First as a fiber to support fibroblast growth in vitro, and second as a demineralized bone/collagen sponge for radial bone defect repair in vivo.For the in vitro study, collagen fibers were prepared as described previously. Primary rat tendon fibroblasts (1° RTF) were isolated and cultured for 5 days on 1 X 15 mm sterile cover slips. Six to seven collagen fibers, were glued parallel to each other onto a circular cover slip (D=18mm) and the 1 X 15mm cover slip populated with 1° RTF was placed at the center perpendicular to the collagen fibers. Fibroblast migration from the 1 x 15mm cover slip onto and along the collagen fibers was measured daily using a phase contrast microscope (Olympus CK-2) with a calibrated eyepiece. Migratory rates for fibroblasts were determined from 36 fibers over 4 days.

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