One example process includes playing, via one or more loudspeakers, one or more audio frequencies at a particular sound pressure level, measuring, via a sensor, a displacement of a laser beam being emitted from a laser source through a slot of a soundbar housing the one or more loudspeakers during the playing, and determining, via a processor, one or more characteristic coefficients of a grommet based on the displacement.

One example process includes playing, via one or more loudspeakers, one or more audio frequencies at a particular sound pressure level, measuring, via a sensor, a displacement of a laser beam being emitted from a laser source through a slot of a soundbar housing the one or more loudspeakers during the playing, and determining, via a processor, one or more characteristic coefficients of a grommet based on the displacement.

Aspects of the present disclosure describe snow / water level detection using distributed fiber optic sensing / distributed acoustic sensing (DFOS/DAS) and an integrated ultrasonic device that advantageously operates over existing optical telecommunications facilities carrying live telecommunications traffic - or optical facilities deployed specifically for such detection. DFOS/DAS monitoring of snow / water level advantageously monitors large areas with high sensitivity while exhibiting robustness to changing environmental conditions and employs a remote (utility pole or other mounting) mounted ultrasonic sensor/transducer that provides snow / water level data in real-time as a coded vibrational signal.

A one-dimensional (1D) and two-dimensional (2D) scan scheme for a tracking continuously scanning laser Doppler vibrometer (CSLDV) system to scan the whole surface of a rotating structure excited by a random force. A tracking CSLDV system tracks a rotating structure and sweep its laser spot on its surface. The measured response of the structure using the scan scheme of the tracking CSLDV system is considered as the response of the whole surface of the structure subject to random excitation. The measured response can be processed by operational modal analysis (OMA) methods (e.g., an improved lifting method, an improved demodulation method, an improved 2D demodulation method). Damped natural frequencies of the rotating structure are estimated from the fast Fourier transform of the measured response. Undamped full-field mode shapes are estimated by multiplying the measured response using sinusoids whose frequencies are estimated damped natural frequencies.

A one-dimensional (1D) and two-dimensional (2D) scan scheme for a tracking continuously scanning laser Doppler vibrometer (CSLDV) system to scan the whole surface of a rotating structure excited by a random force. A tracking CSLDV system tracks a rotating structure and sweep its laser spot on its surface. The measured response of the structure using the scan scheme of the tracking CSLDV system is considered as the response of the whole surface of the structure subject to random excitation. The measured response can be processed by operational modal analysis (OMA) methods (e.g., an improved lifting method, an improved demodulation method, an improved 2D demodulation method). Damped natural frequencies of the rotating structure are estimated from the fast Fourier transform of the measured response. Undamped full-field mode shapes are estimated by multiplying the measured response using sinusoids whose frequencies are estimated damped natural frequencies.

An optical fiber sensor includes an optical fiber. The optical fiber includes a cladding having a cladding refractive index, and a plurality of fiber cores embedded in the cladding and extending along a longitudinal axis of the optical fiber. The plurality of fiber cores include a first subset of at least one first fiber core and a second subset of at least one second fiber core. The at least one first fiber core has a first core refractive index different from the cladding refractive index and a first core radius in a direction transverse to the longitudinal axis. The at least one second fiber core has a second core refractive index different from the cladding refractive index and a second core radius transverse to the longitudinal axis. The second core refractive index and the second core radius differ from the first core refractive index and the first core radius such that a temperature sensitivity of the at least one second fiber core differs from the temperature sensitivity of the first fiber core.

Aspects of the present disclosure describe distributed fiber optic sensing/distributed acoustic sensing (DFOS/DAS) systems, methods, and structures that advantageously provide rainfall intensity measurements along an entire length of a fiber optic sensor. using existing telecommunications optical fiber—which may be part of a multi-fiber, fiber optic cable—that may simultaneously carry live telecommunications traffic. The DFOS/DAS fiber optic sensing is used to obtain vibration and/or sound data from which rainfall intensity measurements may be made along the entire length of the DFOS/DAS fiber optic sensor.

A diagnosis device includes a data acquirer, a data recorder, and a health diagnoser. The data acquirer acquires a measurement data of a structure at a predetermined timing. The data recorder causes a storage to store the measurement data acquired by the data acquirer as a standard data. The health diagnoser diagnoses a health of the structure by comparing the measurement data that is acquired by the data acquirer this time with the standard data that has been acquired by the data acquirer last time and stored in the storage.

Aspects of the present disclosure describe distributed fiber optic sensing (DFOS) systems, methods, and structures that advantageously sense/monitor outdoor facilities and structures including outdoor cabinets containing fiber optic facilities in which the cabinet/fiber optic cable contained therein are configured to provide superior acoustic sensing. Further outdoor facilities and structures that are monitored include manhole structures. Superior DFOS/DAS monitoring results are obtained by employing a machine learning-based analysis method that employs a temporal relation network (TRN).

The disclosure provides a bridge foundation scouring monitoring sensor and a monitoring data analysis method thereof. The disclosed sensor comprises a cover plate, a bottom fixing unit and several standard scouring depth monitoring units fixedly disposed between the cover plate and the bottom fixing unit. Each standard scouring depth monitoring unit comprises an optical fiber vibration string (OFVS) and a supporting frame; the two ends of the OFVS are fixedly connected with the supporting frame; a plurality of polyhedral mass blocks are evenly distributed on the OFBS from top to bottom; and a fiber Bragg grating sensor is disposed at the upper portion of OFBS. The variation of scour depth of bridge foundation induces the change of vibration frequency of the OFVS, which is measured by the fiber Bragg grating sensor. The method of calculating the scour depth from the measured vibration frequency of the OFVS is disclosed.