In this paper, the inverse problem of reconstructing reflectivity function of a medium is examined within a blind deconvolution framework. The ultrasound pulse is estimated using higher-order statistics, and Wiener filter is used to obtain the ultrasonic reflectivity function through wavelet-based models. A new approach to the parameter estimation of the inverse filtering step is proposed in th...

We consider a classifier based on Independent Component Analysis Mixture Modelling (ICAMM) to model the feature jointprobability density. This classifier is applied to a challenging novel application: classification of archaeological ceramics. ICAMM gathers relevant characteristics that have general interest for material classification. It can deal with arbitrary forms of the underlying probabi...

Government agencies and homeland security related organizations have identified the need to develop and establish a wide range of unprecedented capabilities for providing scientific and technical forensic services to investigations involving hazardous chemical, biological, and radiological materials, including extremely dangerous chemical and biological warfare agents. Pacific Northwest Nationa...

Using ultrasonic detection, microhardness test, scanning electron microscope mercury intrusion method and X-ray diffraction, the parameters of sonic time, microhardness, pore size distribution, cumulative pumping high strength concrete under low cycle compression loading are tested after exposure to 200 °C, 400 °C 600 °C. Experimental study showed that with increasing times, rangeability total ...

A prototype wireless guided wave inspection system is developed to inspect layered structures such as aircraft wing. The system includes a stationary antenna and an active antenna as transceivers, an on-board antenna as transponder, and PVDF comb transducers for generating and receiving ultrasonic Lamb waves. Preliminary experiments on a 0.8mm aluminium plate with a 12mm long, 50% through-wall-...

An indication of the formability of metallic sheet is determined using a correlation between nondestructively measurable ultrasonic properties and a formability index. A calibration relation is initially established by measuring ultrasonic velocities at various angles to the rolling direction of sheet specimens with noncontacting electromagnetic acoustic transducers, calculating an ultrasonic c...

Nondestructive evaluation techniques Amlrurn , which use conventional piezoelectric transducers tvDicallv reauire liquid coupling fluids to improve " _ . the impedance mismatch between piezoelectric materials and air. Air-coupled ultrasonic systems can eliminate this requirement if the dynamic range of the system is large enough such that the losses a t the air-solid interfaces are tolerable. C...

Abstract The corner echo is a well-known effect in ultrasonic testing, which allows detection of surface breaking cracks with predominantly perpendicular orientation to the as, for example, corrosion metal pipes or shafts. This formed by two planes, crack and breaks. It can also be classified as half-skip method, since reflection pulse occurs on backwall before at defect takes place. In combina...

Steel strands have been widely used in industrial fields as a reliable load-bearing component. Under the influence of environmental erosion and fatigue stress, different types damage, such corrosion fracture, will occur in-service steel strands, which cause unpredictable loss personnel property. Ultrasonic nondestructive testing technology has become an ideal method for long-distance metal stru...

Pulse-echo reflection techniques are used for ultrasonic flaw detection in most commercial instruments. As the measured pulse echo signal is assumed to be the result of linearly convolving the defect impulse response (IR) with the measurement system response, the objective is thus, to remove the effect of the measurement system through a deconvolution operation and extract the defect impulse re...