Muscle fatigue often occurs over a long period of exercise, and it can increase the risk muscle injury. Evaluating state avoid unnecessary overtraining injury muscle. Ultrasound imaging non-invasively visualize tissue in real-time. Image entropy is commonly used to characterize texture an image. In this study, we evaluated changes ultrasound image (USIE) during process. Twelve volunteers performed static sustained contractions biceps brachii at four different intensities (20%, 30%, 40%, 50%...

We present the focusing structure of a cylindrical acoustic transducer array consisting many annular piezoelectric wafer elements operating in radial vibration mode. Using Huygens' principle, we calculated delay parameters associated with excitation signal each element. Given respective rules, produces an adjustable focused field form 3-D circular ring. From theoretical analysis, designed and fabricated 64 measured its actual distribution. Simulation experimental results show that proposed...

Photoacoustic (PA) imaging technology is of some value in medical diagnoses such as breast cancer detection, vasculature imaging, and surgery navigating. While most objects are bounded, the received RF signals consist direct-arrived (DAS) from PA sources boundary-reflected (BRS). The undesired BRS will severely impair quality during image reconstruction. They bring many artifacts confuse actual shape location sources. We improved reconstruction procedure by removing before regular process to...

Photoacoustic (PA) imaging is a promising technology for functional of biological tissues, offering optical contrast and acoustic penetration depth. However, the presence signal aliasing from multiple PA sources within same object can introduce artifacts significantly impact quality tomographic images. In this study, an optimized method proposed to suppress these enhance image effectively. By leveraging time-frequency spectrum, signals each source be extracted. Subsequently, images are...

Abstract Photoacoustic (PA) imaging owns a great prospect in medical diagnosis because of its high contrast and capability functional imaging. While, the detected PA signals are always mix direct-arrived (DAS) reflected (scattered) (RS) inhomogeneous bounded samples such as human tissues. The RS can lead to many artifacts severely affect final image, which confuses with real sources. This paper employed spatial singular value decomposition (SVD) filter abstract DAS thus remove reflection...

Abstract Sound field visualization of specified frequency is an essential method for acoustic studies, especially in nonlinear acoustics. In this paper, we designed a sound system (SVSF). By combining the traditional scanning with lock-in amplifier (LIA), SVSF can visualize amplitude distribution multiple arbitrary frequencies only one-time scanning. Further, depending on SVSF, analysed effects around focus spherical coronal ultrasonic transducer array. The excitation signal sinusoidal at 40...

The shear wave velocity estimation based on ultrasonic radiation force is the core technology of elastography. Reconstruction images small size inclusions and reasonable removal noise generated during high frequency acquisition are both worthy challenges in We propose a frame fusion imaging method wavelet transform filtering (WT-FFI) to improve such problems. transmission video obtained by frame-frequency compositing processed variation obtain image. theoretical analyses comparative...

Ultrasound levitation technology has been widely applied in various fields. Two main kinds of ultrasound configurations are the standing-wave system and phased array system. Depending on principle focusing transducers, we proposed designed a consists two pairs transducers fitting confocal mode. When paired excited reverse phases, acoustic pressure at geometric focus will be constant 0 Pa, which means potential well exists here. finite element method, simulated field distribution demonstrated...

The array transducer is a key unit to the phased ultrasound imaging systems. While, size error or element failure of elements are often occurred on transducer. Those situations could make serious negative effects acoustic field distribution an and impact quality imaging. In this context, we propose method revise those by adjusting excitation parameters elements. theoretical analysis experiments results indicate that effective feasible optimizing image gathered with some failed

Overtraining under muscle fatigue will greatly increase the risk of injury, therefore objective and accurate assessment is great significance for exercise guidance. Muscle embodies reduction force changes in microstructure. The microstructure affect its acoustic transmission characteristics. In this paper, we study ultrasonic attenuation coefficient as an indicator assessing fatigue. Eight healthy young males participated experiment, none them had a history neuromuscular disease. We...

Coupling effects in waveguides have attracted much attention of researchers electromagnetism and optics, where they are widely employed controlling steering optical waves. Nevertheless, coupling acoustic-cladded received scant reporting. In this paper, we examine the three parallel acoustic waveguides. Using finite-difference time-domain method, input modes simulated analyzed. The instantaneous pressure distributions structures demonstrated, effective against propagation distance was...

The characteristics and mechanism of coupling effects between parallel cladded acoustic waveguides (PCAWs) are essential when considering their applications in wave control signal processing. We investigated its revealed the nature effect using a theoretical model two-dimensional PCAWs simulation experiments. derived eigenmode equation describing behavior single waveguide based on theory analytic expressions for coupled mode theory. Using finite-element method, we analyzed exhibited by this...

Acoustic holography is an essential tool for controlling sound waves, generating highly complex and customizable fields, enabling the visualization of fields. Based on acoustic sieve metasurfaces (ASMs), this paper proposes a theoretical design approach zero-thickness broadband holograms. The ASM rigid screen with large number small holes that allow waves to pass through produce desired real image in target plane. hole arrangement rules are determined using genetic algorithm...

Ultrasound sources of an appropriate size and controllable power are crucial for extensive investigations applications, especially in exploratory experiments needing precise ultrasound stimulations. We designed acoustic wave funnel (AWF) that changes the source to a suitable acts as small suited widespread applications. The AWF consists three parts—two cladded waveguides different radii connected by hollow cone. larger waveguide has same radius transducer, whereas smaller is set application...

The timely assessment of muscle fatigue makes sense for reducing the risk musculoskeletal injury during exercise. In general, is accompanied by physiological changes. These changes affect acoustic transmission properties skeletal muscles. This study investigated variation spectrum (ATS) human upper arm muscles sustained static contractions (SC). Based on B-ultrasound image and radiofrequency (RF) ultrasonic echoes, we abstracted RF echo signals from subcutaneous fatty/fascia (SFF) deep...

Skeletal muscle is crucial for human body movement and function. In recent years, B-mode ultrasound imaging has become widely used to assess the function condition of skeletal muscle. Precisely assessing properties important medical diagnoses. However, noise in images complicates analysis. We propose a three-stage filtering technique mark fibers an image. Experimental results verify that method effective feasible marking fibers. This can potentially be analyze many aspects including...

The phased-array ultrasonic levitation is a convenient technique to manipulate particles. In order provide convenience for both professional and nonprofessional users use the phase array technique, we designed man-machine interactive system. It consists of interaction module, multi-channel transmitting circuit an transducer module. module can calculate corresponding sequence according user-defined position angle. transmitter provides electrical excitation calculated sequence. They...