Operating parameters are selected for inspecting a structure. Selecting the operating parameters includes exciting broadband ultrasonic guided waves in a multilayered structure, acquiring data corresponding to the sensed broadband ultrasonic guided waves in the multilayered structure, selecting one or more narrow frequency bands based on the acquired data, and inspecting the multilayered structure using ultrasonic guided waves in the one or more narrow frequency bands. In some examples, the data is acquired by an inspection tool capable of sensing the broadband ultrasonic guided waves in the multilayered structure.

Operating parameters are selected for inspecting a structure. Selecting the operating parameters includes exciting broadband ultrasonic guided waves in a multilayered structure, acquiring data corresponding to the sensed broadband ultrasonic guided waves in the multilayered structure, selecting one or more narrow frequency bands based on the acquired data, and inspecting the multilayered structure using ultrasonic guided waves in the one or more narrow frequency bands. In some examples, the data is acquired by an inspection tool capable of sensing the broadband ultrasonic guided waves in the multilayered structure.

An acoustic emission wave detector includes a housing, an optical fiber that guides light from a wideband light source into the housing, and an FBG housed in the housing and having a diffractive grating that reflects light guided into the housing. The FBG is fixed on a side of the other end in the housing such that the light guided into the housing is received by one end thereof. An acoustic emission wave from a high-voltage apparatus is received by the other end thereof.

A system for detecting structural damage to a rigid structure, the system comprising: at least one impact generator capable of applying a one-time impact on the structure; an acoustic sensor; a vibration sensor; and a processing circuitry configured to: provide an indication of the structural damage to the rigid structure upon (a) a first deviation above a first threshold between an expected acoustic wave profile, expected to radiate from the structure, absent the structural damage, and an actual acoustic wave profile being measured by the acoustic sensor in response to an application of the one-time impact, or (b) a second deviation above a second threshold between an expected to vibration profile of expected vibrations of the structure, absent the structural damage, and an actual vibration profile in response to the application.

The invention generally provides a system and method for detecting, measuring, and/or classifying particulate and/or water contaminants in a fluid supply line, storage tank, or sump. Embodiments of the invention provide a contaminant detection apparatus with a detection chamber and a detection module. The detection chamber includes a housing with an internal fluid conduit and one or more acoustic transducers disposed in the housing. Alarms and/or automatic signaling may be included to shut off valves or pumps when contaminants are detected.

When frequencies used in the two-frequency measurement of a SAW sensor are represented by f.sub.1 and f.sub.2 (f.sub.2>f.sub.1), an electrical signal processing device is provided without use of oversampling at a frequency higher than twice the frequency f.sub.2 or a two-system low-frequency conversion circuit, in which temperature compensation with the same accuracy as the case where these are used can be realized. Narrow band frequency filtering is applied to a waveform after roundtrips in a delay line type SAW sensor capable of transmitting and receiving multiple frequencies, the two frequencies f.sub.1 and f.sub.2 (f.sub.2>f.sub.1) are extracted, and a delay time is determined utilizing an aliasing obtained by applying undersampling at a frequency lower than twice the frequency f.sub.1.

When frequencies used in the two-frequency measurement of a SAW sensor are represented by f.sub.1 and f.sub.2 (f.sub.2>f.sub.1), an electrical signal processing device is provided without use of oversampling at a frequency higher than twice the frequency f.sub.2 or a two-system low-frequency conversion circuit, in which temperature compensation with the same accuracy as the case where these are used can be realized. Narrow band frequency filtering is applied to a waveform after roundtrips in a delay line type SAW sensor capable of transmitting and receiving multiple frequencies, the two frequencies f.sub.1 and f.sub.2 (f.sub.2>f.sub.1) are extracted, and a delay time is determined utilizing an aliasing obtained by applying undersampling at a frequency lower than twice the frequency f.sub.1.

Aspects provide for in-situ monitoring of a structure, such as a portion of an in-operation vehicle, by a patch and controller by transmitting, at a first time, a first signal from a first transceiver of a plurality of transceivers in contact with the structure; receiving the first signal carried in the structure at a second transceiver of the plurality of transceivers at a known distance from the first transceiver; determining a baseline signal characteristic of the first signal as received at the second transceiver; transmitting, at a second time, a second signal from the first transceiver; receiving the second signal carried in the structure at the second transceiver; determining a diagnostic signal characteristic of the second signal as received at the second transceiver; and in response to determining that a difference between the baseline signal characteristic and the diagnostic signal characteristic exceeds a threshold, generating an alert.

Aspects provide for in-situ monitoring of a structure, such as a portion of an in-operation vehicle, by a patch and controller by transmitting, at a first time, a first signal from a first transceiver of a plurality of transceivers in contact with the structure; receiving the first signal carried in the structure at a second transceiver of the plurality of transceivers at a known distance from the first transceiver; determining a baseline signal characteristic of the first signal as received at the second transceiver; transmitting, at a second time, a second signal from the first transceiver; receiving the second signal carried in the structure at the second transceiver; determining a diagnostic signal characteristic of the second signal as received at the second transceiver; and in response to determining that a difference between the baseline signal characteristic and the diagnostic signal characteristic exceeds a threshold, generating an alert.

Provided are an apparatus and a method for measuring a nonlinearity parameter using laser, and more particularly, an apparatus and a method for measuring a nonlinearity parameter using laser for computing the nonlinearity parameter by irradiating laser of a toneburst signal on a surface of a sample by non-contact type laser so as to excite the sample, irradiating measurement laser beam on the surface of the sample so as to receive displacement information occurring on the surface of the sample over time, measuring the displacement in an interferometer principle, and performing a bandpass filtering for the measured signal so as to measure amplitude A.sub.1 of a component of a fundamental frequency and amplitude A.sub.2 of a component of a secondary harmonic wave.