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...

Detection of debris flow occurrence can be efficiently obtained through different types of sensors. A pair of ultrasonic sensors placed at a known distance from each other along a torrent have been used as a method to obtain mean front velocity of debris-flows, in addition to their use as detectors of debris flow occurrence. Also seismic and acoustic sensors have been employed to measure debris...

A fine grain, relaxor-based piezoelectric ceramic 0.7 Pb(Mg(1/3)Nb(2/3))O3-0.3PbTiO3 (PMN-30% PT) has been investigated, which was fabricated using the columbite precursor method. The complete set of electromechanical properties of the piezoceramic at room temperature is determined using a combination of ultrasonic and resonance techniques. This fine-grain ceramic (grain size < or = 2.5 microm)...

Ultrasonic non-destructive testing is a sensitive tool not only for defect detection and evaluation in plant components and structures, but also to characterise microstructural features and for evaluation of mechanical properties. Even though, it provides high sensitivity and reliability for such measurements and very versatile to use at ambient temperatures, the technique fails when it is exte...

-The ultrasonic velocity at 100MHz and room temperature (23-26°C) was measured in fresh, excised mammalian liver, kidney, spleen, and pancreas and mouse kidney. The results show excellent agreement with measurements at low MHz frequencies. A significant velocity difference is reported between kidney cortex and medulla, but no difference was observed between the exocrine and islets of Langerhans...

A thermodynamic method capable of determining the B/A value of 4-ml sample volumes is described. The method involves a procedure in which the static pressure of the sample is altered in a short period of time, to approximate an adiabatic process, during which the ultrasonic velocity is measured. The velocity change so determined is used to calculate the B/A value. The B/A measurement error is l...

The advent of dry point transducers has allowed new possibilities for ultrasonic testing of concrete structures and rock specimens. Recent developments in the technology such as single and multi-channel ultrasonic pulse echo technology and the automated determination of the modulus of elasticity have been pushing back the boundaries of the method. The effect of this has been to increase the eas...

Ultrasonic measurements of elastic moduli of composite materials have traditionally been made on either small specimens cut from a iar ger component or by using a scanning technique with the specimen immersed in a water bath. A phase-insensitive array has been developed for rapid nondestructive measurement of in-plane elastic moduli. The array characteristics allow for determinat ion of energy ...

The paper shows how the precise knowledge of the sound field of an ultrasonic annular array can contribute to the development of novel measurement techniques. Emphasis is placed on (a) a non-invasive method for sound velocity measurements in fluids using the echo signals from scattering p]articles, (b) a non-invasive method for the combined determination of thickness and sound velocity in layer...