An inspection system includes an image processing unit that suppresses noise of a complex number image on which pixels are represented by a complex number indicating a periodic change in a vibration state of an inspection target. The image processing unit acquires a degree of similarity between a pixel included in a target image region defined in the complex number image and a pixel included in a plurality of reference image regions defined in the complex number image separately from the target image region by comparing complex numbers representing pixels, and executes noise suppression processing of the target image region by using a weight based on the acquired degree of similarity.

A method of monitoring fluid outflow along a wellbore includes obtaining an acoustic signal from a sensor within the wellbore, determining one or more frequency domain features from the acoustic signal, and identifying one or more fluid outflow locations along the portion of the depth of the wellbore using the one or more frequency domain features. The acoustic signal includes acoustic samples across a portion of a depth of the wellbore.

A switchgear includes an optical monitoring system for examining switchgear switching positions. At least one isolating switch is accommodated in an encapsulated housing. The encapsulated housing is disposed in an installation housing. The encapsulated housing has a first transparent window in one region. A fiber-optic system leads from an outer side of the installation housing to the first transparent window.

Using at least one sensor positioned to monitor a fluid conduit, an acoustic event is detected. A speed of sound of the acoustic event is determined. The speed of sound of the acoustic event is compared to a baseline speed of sound. Based on the comparison, whether or not a leak has occurred in the fluid conduit may be determined.

According to examples, an optical fiber-based sensing membrane may include at least one optical fiber, and a substrate. The at least one optical fiber may be integrated in the substrate. The optical fiber-based sensing membrane may include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. The substrate may include a thickness and a material property that are specified to ascertain, via the at least one optical fiber and based on the optical fiber-based sensing membrane layout, a thermal and/or a mechanical property associated with a device, or a radiation level associated with a device environment.

Disclosed is a signal processing method for a distributed acoustic sensing system (DAS), where a scattered signal that was scattered at a scattering location along an optical path is received and interfered with a local oscillator signal to generate a first carrier signal that is modulated by a phase difference between the local oscillator signal and the scattered signal. The first carrier signal is then digitally processed in order to generate a second carrier signal that is modulated by a spatial differential of the phase difference. The spatial differential of the phase difference is directly related to the strain (or acoustic environment) of the optical path at the scattering location, and so enables the strain at the scattering location to be estimated.

Methods and systems are provided for monitoring subsurface steam chamber development in a thermal hydrocarbon recovery operation, which employ a fiber optic cable in a horizontal wellbore beneath the steam chamber as part of a distributed acoustic sensing technique in which the cable receives attenuated sound waves passing through the steam chamber and transmits a signal corresponding to the attenuated sound waves and unattenuated sound waves for subsequent signal processing.

A system, apparatus, and method for remotely detecting defects in a structure may proceed non-destructively. A mobile sensing platform may place sensors in a desired positioning relative to the structure. The desired position may include a non-contacting relation between the sensors and structure. The mobile sensing platform may project laser beams onto the structure and sense backscattered light via the sensors. Variations in the backscattered light may correspond to motion of the structure, such as vibrations. By calculating the frequency and amplitude of the vibrations, defects in the structure may be detected. By correcting for noise, such as that associated with acceleration of the mobile sensing platform, accuracy and precision of defect detection may be enhanced.

A system, apparatus, and method for remotely detecting defects in a structure may proceed non-destructively. A mobile sensing platform may place sensors in a desired positioning relative to the structure. The desired position may include a non-contacting relation between the sensors and structure. The mobile sensing platform may project laser beams onto the structure and sense backscattered light via the sensors. Variations in the backscattered light may correspond to motion of the structure, such as vibrations. By calculating the frequency and amplitude of the vibrations, defects in the structure may be detected. By correcting for noise, such as that associated with acceleration of the mobile sensing platform, accuracy and precision of defect detection may be enhanced.

There is described a method for interrogating optical fiber comprising fiber Bragg gratings (“FBGs”), using an optical fiber interrogator. The method comprises (a) generating an initial light pulse from phase coherent light emitted from a light source, wherein the initial light pulse is generated by modulating the intensity of the light; (b) splitting the initial light pulse into a pair of light pulses; (c) causing one of the light pulses to be delayed relative to the other of the light pulses; (d) transmitting the light pulses along the optical fiber; (e) receiving reflections of the light pulses off the FBGs; and (f) determining whether an optical path length between the FBGs has changed from an interference pattern resulting from the reflections of the light pulses.