Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System(DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a seco...

Condition monitoring has a great potential for enhancement in the reliability of operation, machine up-time, reduction in consequential damage and improving operational efficiency at lower operational cost. In electrical equipment incipient faults are often characterized by variations in temperature, vibro-acoustic signature, etc. Different condition monitoring techniques use dedicated sensing ...

During the Shallow Water 2006 Experiment, SW06, a power supply for seabed-moored oceanographic equipment suffered an accidental explosion. The equipment was located on the New Jersey Shelf, 175 kilometers south-east of New York. Acoustic signals emitted by the explosion were detected by hydrophone sensors that form part of the International Monitoring System (IMS) of the Comprehensive Test-Ban ...

A preliminary evaluation of several nondestructive testing methods for flaw detection in hightemperature structural ceramic components is being carried out. The ceramics components being investigated include silicon carbide heat-exchanger tubes and silicon nitride rotors. The nondestructive evaluation techniques under consideration include dye-enhanced radiography, holographic interferometry, i...

According to WHO, at any one time, around 50 per cent of medical equipment in lowand middle-income countries cannot be used because of lack of maintenance or spare parts.1 We have found that unwillingness or inability to repair equipment and put it back in use is also a major cause. New equipment is made available by different international non-government organisations (INGOs) competing with on...

Regular monitoring of some geophysical parameters in association with seismicity has been carried out since last year at the Japan-Russian Complex Geophysical Observatory in the Kamchatka region. This observatory was organized in connection with the ISTC project in Russia and was motivated by the results of the FRONTIER/RIKEN and FRONTIER/NASDA research projects in Japan. The main purpose of th...

Frequency dependent measurements of attenuation and/or sound speed through clouds of gas bubbles in liquids are often inverted to find the bubble size distribution and the void fraction of gas. The inversions are often done using an effective medium theory as a forward model under the assumption that the bubble positions are Poisson distributed (i.e., statistically independent). Under circumsta...

Acoustic echo control is of vital interest for hands-free operation of telecommunications equipment. An important property of an acoustic echo controller is its capability to handle double-talk and be able to operate in real time. In this paper, we propose a novel hardware architecture to support a robust adaptive algorithm in combination with a two-path model to tackle the double-talk situatio...

The impulse response (IR) of an acoustic channel can be obtained by cross-correlating the received signal with the broadband excitation signal in unfavorable noise conditions. However, the deconvolved IR is colored by the IRs of the combined electrical equipment. This letter presents a time domain approach using pre-computed filters to whiten the unknown coloration in order to obtain the channe...