An apparatus for detecting a transient event in an operating machine, the apparatus comprising: a controller configured to control performance of the following steps: a measurement step comprising measuring a periodic signal from a machine; a processing step comprising synchronously processing the periodic signal to track the primary frequency; a filtering step comprising removing the primary periodic component and its harmonics from the periodic signal to yield a filtered dataset; an integration step comprising integrating the filtered dataset over the remaining frequencies to yield an integrated dataset representing the periodic energy at frequencies other than the primary frequency and its harmonics; an analysis step comprising identifying a short-term transient in the integrated dataset to identify a transient disruption in the operation of the machine.

Data retrieval, event recording and transmission module connectable to safety and relief valves. The module (10) coupled to safety or relief valves for the measurement, transmission and recording of events and includes a rigid and inextensible at room temperature longitudinal element defining an acoustic emission waveguide (12) that transmits vibrations. The end (12a) of (12) is in intimate contact with a portion (2) or (1) of the valve, and its other end (12b) penetrates inside a closed resistant box (10), wherein it sits in contact against at least one acoustic emission sensor (13) receiving a signal proportional to the vibrations transmitted by the waveguide (12).

A method for detecting faults in plates includes the steps of: transmitting an acoustic signal towards the plate from a transmitting transducer, and receiving the acoustical signal from the plate in a receiving transducer. The receiving transducer is mounted at a distance from the transmitting transducer. The method includes the further steps of identifying zones of the plate wherein energy levels of the received signals are attenuated compared to other zones of the plate, and comparing the energy levels of the A.sub.2 and S.sub.3 guided Lamb modes in the received signals in the identified zones.

Methods, apparatus, and articles of manufacture are disclosed. An example pre-amplifier includes a demodulator to generate an oscillating signal having a measurement center frequency, combine an acoustic emission signal and the oscillating signal to generate a sideband acoustic emission signal, sample spectral data of the sideband acoustic emission signal at an intermediate center frequency in an intermediate frequency bandwidth, and generate demodulated acoustic emission data based on a mapping of the sampled spectral data to the measurement center frequency, the measurement center frequency different from the intermediate center frequency, and a transmitter to transmit the demodulated acoustic emission data to a computing device.

Methods, apparatus, and articles of manufacture are disclosed. An example pre-amplifier includes a demodulator to generate an oscillating signal having a measurement center frequency, combine an acoustic emission signal and the oscillating signal to generate a sideband acoustic emission signal, sample spectral data of the sideband acoustic emission signal at an intermediate center frequency in an intermediate frequency bandwidth, and generate demodulated acoustic emission data based on a mapping of the sampled spectral data to the measurement center frequency, the measurement center frequency different from the intermediate center frequency, and a transmitter to transmit the demodulated acoustic emission data to a computing device.

A non-transitory computer-readable storage medium storing a program that causes a computer to execute a process, the process includes acquiring first sound data collected by a first microphone and second sound data collected by a second microphone during traveling of a vehicle in which the first microphone is provided in vicinity of a front wheel and the second microphone is provided in vicinity of a rear wheel; and detecting a cavity under a road surface where the vehicle has traveled based on a difference between the acquired first sound data and the acquired second sound data.

A fuel flow measuring system includes an ultrasonic fuel flow sensor. The fuel flow sensor includes a first transducer and a second transducer. The first transducer is excited at multiple different excitation frequencies and a voltage, an electric current, and a phase difference between the voltage and the electric current is sensed at the first transducer during excitation. Data points are generated based on the sensed readings and a model is fit to the data points to determine a complex impedance spectrum. The complex impedance spectrum indicates a range of excitation frequencies within a range of a peak resonance frequency of the first transducer. One or more characteristics of excitation signals directed to the second transducer are set based on the determined complex impedance spectrum. In this manner, the signal to noise ratio of ultrasonic signals emitted by the second transducer and received by the first transducer can be maximized.

An apparatus may include one or more optical fibers, one or more optical waveguides, and multiple resonator nodes arranged in an array of sensing locations. Each resonator node may include an optical coupling between an optical waveguide and an optical fiber having a set of resonant frequencies at a respective sensing location. Each resonator node may be further configured to communicate a set of signals corresponding to at least one shift in the set of resonant frequencies in the optical fiber at the respective sensing location.

An asphalt density estimation system includes a measurement device configured to output a measurement signal; a time synchronization unit configured to sample the measurement signal to obtain a sampled measurement signal and identify periodic sampling points of the sampled measurement signal across a plurality of periods. The system also includes a time synchronous averaging unit configured to construct a modified measurement signal in the time domain by: for at least one sampling point within the period, averaging a plurality of the periodic sampling points across periods to obtain an average periodic data point for the at least one sampling point, and constructing the modified measurement signal using the average periodic data point for the at least one sampling point. The system further includes a density calculation unit configured to determine asphalt density values based on the modified measurement signal; and a display unit configured to display the determined asphalt density values.

An asphalt density estimation system includes a measurement device configured to output a measurement signal; a time synchronization unit configured to sample the measurement signal to obtain a sampled measurement signal and identify periodic sampling points of the sampled measurement signal across a plurality of periods. The system also includes a time synchronous averaging unit configured to construct a modified measurement signal in the time domain by: for at least one sampling point within the period, averaging a plurality of the periodic sampling points across periods to obtain an average periodic data point for the at least one sampling point, and constructing the modified measurement signal using the average periodic data point for the at least one sampling point. The system further includes a density calculation unit configured to determine asphalt density values based on the modified measurement signal; and a display unit configured to display the determined asphalt density values.