We describe the design and construction of a relatively simple, inexpensive laser interferometer system for accurate measurements of ultrasonic surface displacement waveforms in reasonably friendly environments. We show how analysis of a single waveform can provide both the calibration constant required for absolute measurements and an estimate of the uncertainty of these measurements. We demon...

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With advances in technology and people’s increasing emphasis on health issues, there has been a rapid development of wearable and implantable biomedical sensors. However, radio frequency waves dominate wireless communications, despite disadvantages such as high attenuation in the human body, considerable power consumption, and complicated wireless antenna design, which has hampered the developm...

Guided wave imaging with a sparse array of inexpensive transducers offers a fast, reliable, and cost-efficient means for damage detection and localization in plate-like structures such as aircraft and spacecraft skins. As such, this technology is a natural choice for inclusion in condition-based maintenance and integrated structural health management programs. One of the implementation challeng...

Simulating the propagation of 3D ultrasonic waves in a nonlinear medium is a demanding task. It requires the solution of time-dependent and nonlinear partial differential equations (PDEs). For such nonlinear PDEs, we have to use an implicit numerical method that is very CPUintensive. Parallel simulation is therefore essential for studying those ultrasonic waves with satisfactory accuracy. We pr...

A combination of laser-induced ultrasound generation and ultrasonic holography for spatial control of the generated ultrasonic pulse is presented. Ultrasound is produced by absorption of laser pulses at an absorbing layer in a water tank via the optoacoustic effect. In order to produce a defined ultrasonic frequency in the MHz range, the laser pulses are harmonically time-modulated using an aco...

Ultrasonic methods have been implemented for in situ sizing of fatigue cracks near fastener holes. These techniques, however, only provide an estimate at the time of the measurement and cannot predict the remaining life of the structure. In contrast, statistical crack propagation approaches model the expected fatigue life based on worst-case fatigue process assumptions. The authors have recentl...

The ultrasonic infrared thermal wave method is a new nondestructive testing technique. It is remarkably sensitive and convenient for detection of small vertical cracks, such as fatigue cracks in metals. Pulses of ultrasonic launched by the ultrasonic emitter as heat source are excited into the sample, if there are some cracks in the material, they will be revealed through their heat generation,...

Diffuse ultrasonic backscatter measurements have been especially useful for extracting microstructural information and for detecting flaws in materials. Accurate interpretation of experimental data requires robust scattering models. Quantitative ultrasonic scattering models include components of transducer beam patterns as well as microstructural scattering information. Here, the Wigner distrib...

Transcranial magneto-acoustical stimulation (TMAS) is a novel stimulation technology in which an ultrasonic wave within a magnetostatic field generates an electric current in an area of interest in the brain to modulate neuronal activities. As a key part of the neural network, neurons transmit information in the nervous system. However, the effect of TMAS on the neuronal firing pattern remains ...