Piezoelectric wafer active sensors (PWAS) are inexpensive, non-intrusive un-obtrusive devices that can be surface-mounted on existing structures, or inserted in a new composite structure. The PWAS can be used in both active and passive modes. In active mode, the PWAS generate Lamb waves that can exist as either traveling waves or standing waves. As traveling waves, PWAS-generated Lamb waves can...

BACKGROUND Cartilage elasticity changes with cartilage degeneration. Hence, cartilage elasticity detection might be an alternative to traditional imaging methods for the early diagnosis of osteoarthritis. Based on the wave propagation measurement, Shear wave elastography (SWE) become an emerging non-invasive elasticity detection method. The wave propagation model, which is affected by tissue sh...

The propagation of surface waves in a fluid- saturated porous isotropic layer over a semi-infinite homogeneous elastic medium with an irregularity for free and rigid interfaces have been studied. The rectangular irregularity has been taken in the half-space. The dispersion equation for Love waves is derived by simple mathematical techniques followed by Fourier transformations.  It can be seen t...

In different industrial branches, it is necessary to characterize liquids in closed containers. For small cans, accessibility to both sides is almost trivial. However, in industries in which larger containers are used, and especially in the dock industry, only one side is accessible practically; and damping often prevents through-transmission ultrasonic measurements or pulse echo techniques. It...

it is very important to study and simulate s-wave structure for near surface (alluvium parts, in particular) owing to its direct relationship to urban facilities in geotechnical and earthquake engineering studies. so, in seismic microzonation, the first step is to study and identify s-wave pattern in alluvium in order to categorize different parts of cites according to s-wave velocity. current ...

The special form of pipe-like structure provides the helical route for ultrasonic guided wave. Considering pipe as a flattened plate but with periodical replications, wave becomes intuitional and corresponding imaging algorithm can be constructed. This work proposes multihelical Lamb method by utilizing multiple arrival wavepackets which are denoted different orders. signal model is presented c...

Lamb waves are currently used in many nondestructive testing applications to determine or monitor elastic properties of plate-like Structures using various excitation methods. The methods vary from point-like dry contact transducers and laser ultrasound techniques in hostile environments to wedge transducers for inspection of excitation of Lamb waves in 2-D geometry by surface immersed structur...

Accurate knowledge of the velocity dispersion of Lamb modes is important for ultrasonic nondestructive evaluation methods used in detecting and locating flaws in thin plates and in determining their elastic stiffness coefficients. Lamb mode dispersion is also important in the acoustic emission technique for accurately triangulating the location of emissions in thin plates. In this research, the...

In different industrial branches, it is necessary to characterize liquids in closed containers. For small cans, accessibility to both sides is almost trivial. However, in industries in which larger containers are used, and especially in the dock industry, only one side is accessible practically; and damping often prevents through-transmission ultrasonic measurements or pulse echo techniques. It...

A novel Lamb wave resonator with fully suppressed acoustic radiation in water is proposed for high-resolution mass-sensitive detection of biomolecules. The elimination achieved by slowing down the to a velocity lower than sound speed water. This enables high-quality-factor resonance and reduces sensing frequency noise. High aspect ratio electrodes (HAREs) are used slow wave. elastic large surfa...