Abstract: Method and a device for detecting defects in an elongated structure able to act as an elastic-wave waveguide, the elongated structure being fitted with a plurality of transducers able to acquire measurement signals of characteristic quantities of elastic waves propagating in the elongated structure, each transducer being coupled to an electronic device, the set of electronic devices constituting a network of nodes configured to process measurement signals received from at least one transducer.

Abstract: A method and a device for managing resources for monitoring elongate structures that can serve as elastic waveguides are provided. The structure is instrumented with a plurality of transducers capable of acquiring signals measuring characteristic quantities of elastic waves being propagated in the structure, each transducer being coupled to an electronic device installed along the structure.

Abstract: A method for software update of software embedded in an electronic device having a nominal operating mode making it possible to exchange messages with a remote server according to a long-range low-speed communication protocol, where the messages contain information generated by the embedded software. The method is computer-implemented and comprises at least steps consisting in: receiving, via the long-range low-speed communication protocol, a message for activating a short-range high-speed communication protocol; activating the short-range high-speed communication protocol; halting the nominal operating mode; and updating the embedded software with a software update received via the short-range high-speed communication protocol.

Abstract: Methods and devices for detecting a defect in a rail of a railway track, include at least two sensors selected from among magneto-acoustic and/or piezoelectric and/or magnetostrictive transducers; each sensor being associated with a timestamping circuit of a GNSS satellite positioning system; a measuring circuit for measuring, by way of the sensors, the acousto-elastic waves propagating in the rail, the wave or signal measurements being timestamped. Some developments describe notably active and passive modes; the use of train crossings; the emission of waves; the determination of the existence and then of the position and finally the characterization of the defect, where applicable; preferred placements for installing the sensors; the use of inter-correlation, passive inverse filter or correlation of coda of correlation methods; the use of mobile robots and/or drones; the use of artificial noise sources.

Abstract: Methods and devices are provided for analyzing a tubular structure including at least two electromagnetic-acoustic transducers (EMAT) and, called sensors, attachable or attached in, on or in the vicinity of the tubular structure; and computation and/or memory resources, that are accessed locally and/or remotely and that are configured to determine, for the pair of sensors, a function representing the impulse response of the tubular structure on the basis of the diffuse acousto-elastic noise present in the structure. Developments describe the use of rings supporting the sensors; translation and/or rotation movements; permanent or temporary installations; hinged rings; various computation modes, e.g., intercorrelation, a passive inverse filter, or correlation of the coda of the correlation; the use of artificial noise sources, imaging (e.g., tomography) for determining the existence of one or more defects in the structure. Software aspects are described.

Abstract: A method and system for inspecting a rail by guided waves, the rail being instrumented by sensors. The method comprises the steps of receiving elastic wave measurements from one or more sensors, as a train passes, releasing energy as guided waves into the rail; and of determining a function representative of the impulse response of the rail and the sensors. Developments describe how to determine the existence, position and characterisation of a defect in the rail (e.g. fracture, incipient fracture, etc.), the use of inter-correlation analyses, correlation of the coda of correlations, Passive Inverse Filter, imaging techniques. Other aspects are described for exploring rail defects: sensor position and movement, acquisition time, sampling frequency, frequency filters, amplifications, techniques for learning during successive train passes, signal injection by transducers. Software aspects are described.

Abstract: Methods and systems for analyzing an industrial structure are provided. With a plurality of sensors (e.g. FBGs and/or piezoelectric transducers and/or electromagnetic acoustic transducers) deployed in, on or in proximity to the structure, sensors are interrogated and a function representative of the impulse response of the structure is determined by passive inverse filter. Subsequently, a map of the propagation of the elastic waves through the structure is determined via various modalities, and in particular by tomography (of bulk or guided waves, by analysis of time of flight or of the complete signal). Embodiments especially relate to the management of the number and position of the sensors, to the use of artificial noise sources, and to automatically controlling the sensors and/or noise sources to monitor the health of the structure, or even to view the dynamic behavior of the structure.

Abstract: A method for monitoring the structural health of a structure that supports guided propagation modes of elastic waves, includes the following steps: a) acquiring an ambient noise propagating through the structure by means of at least one pair of non-collocated elastic-wave sensors; b) estimating a function representative of an impulse response of the structure for elastic propagation between the constituent sensors of said pair; c) extracting at least one dispersion curve of the elastic propagation through the structure by time-frequency analysis of this function representative of an impulse response; and d) estimating at least one parameter indicative of a mechanical property of a constituent material of the structure from the dispersion curve obtained in step c). A system for implementing such a method is also provided.

Abstract: A method and a device for analyzing a structure by tomography and diffuse acousto-elastic field correlation are provided. An optical fiber comprising a plurality of measurement points of FBG (Fiber Bragg Grating) type, comprising sensors of Bragg grating type, is deployed in or on the structure to be analyzed. The method comprises the emission of light, into the optical fiber, and the measurement by correlation for each pair of FBG sensors. In a development, a prior imaging of the structure is performed by reconstruction of the velocities of propagation. Other developments comprise: the determination of the positions of the FBG sensors, the calibration of the tomography, the rosette configuration of the sensors forming the measurement points, the use of a plurality of optical fibers, of multiplexers, of lasers, of optical circulators, of omnidirectional optical sensors, of active noise sources, such as piezoelectric transducers, incorporated or not in the structure.