A tunnel defect detection and management system based on a vibration signal of a moving train. This system identifies the defects in a subway tunnel structure and soil behind a wall through the acquisition, transmission and analysis of an on-board acceleration signal. A signal acquisition sensor is mounted on the moving train. A signal acquisition module and a signal transmission system are mounted in the train to preprocess and compress the signal. A data processing and analysis server performs data analysis to quickly identify the defects of the tunnel and the auxiliary structure thereof, and determine a defect location and type. A tunnel management platform releases real-time detection information and health status of the tunnel, alarms for the defects, and releases the defect data to relevant personnel to take measures.

An inspection apparatus for enabling a remotely-located expert to monitor an inspection by a non-expert, the apparatus comprising an inspection device capable of being operated by the non-expert, which is configured to generate inspection data indicative of a condition of a test object, and a communication unit configured to: divide the inspection data into first and second data; transfer the first data for being presented to the remotely-located expert at a first time, to facilitate substantially real-time monitoring of the inspection by the expert; and transfer the second data for being presented to the remotely-located expert at a second time, which is later than the first time, to facilitate non-real time monitoring of the inspection by the expert.

Methods, systems, and computer-readable storage media for accurate time delay estimation using coherent averaging. A plurality of out-of-bracket acoustical impulses are generated in a pipe segment of a fluid distribution system. Signal data representing the acoustical impulses sensed at two locations along the pipe segment are recorded. Precise timings for the generation of the acoustical impulses are obtained, and the acoustical impulses in the signal data recorded from the first location are averaged based on the precise timings to produce a near-sensor average impulse. Similarly, the acoustical impulses in the signal data recorded from the second location are averaged based on the same precise timings to produce a far-sensor average impulse. A time delay between arrival of the plurality of out-of-bracket acoustical impulses at the first and second locations is estimated from the timing of the near-sensor average impulse and the far-sensor average impulse.

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.

According to one implementation, an ultrasonic inspection system includes: a first inspection unit, a second inspection unit, and a signal processing system. The first inspection unit acquires a detection signal of a first ultrasonic wave in a first inspection section of an structural object, using a first ultrasonic transducer and a first ultrasonic sensor. The second inspection unit acquires a detection signal of a second ultrasonic wave in a second inspection section of the structural object, using a second ultrasonic transducer and a second ultrasonic sensor. The signal processing system obtains an index value representing inspection information of at least one of the first inspection section and the second inspection section, based on the detection signal of the first ultrasonic wave and the detection signal of the second ultrasonic wave.

Described here are systems and methods for phase velocity imaging using an imaging system, such as an ultrasound system, an optical imaging system (e.g., an optical coherence tomography system), or a magnetic resonance imaging system. In general, systems and methods for constructing phase velocity images (e.g., 2D images, 3D images) from propagating mechanical wave motion data are described. The systems and methods described in the present disclosure operate in the frequency domain and can be implemented using a single frequency or a band of selected frequencies. If there are multiple mechanical wave sources within the field-of-view, directional filtering may be performed to separate mechanical waves propagating in different directions. The reconstructions described below can be performed for each of these directionally filtered components.

An ultrasonic scanner acquires a gain profile including gain values for corresponding travel times in ultrasonic echoes reflected by a reference object. An ultrasonic probe signal is sent toward a test object. In response, an ultrasonic echo reflected by the test object is received at the scanner. A time of arrival of the echo is estimated. The gain profile is aligned with the echo according to the estimated time of arrival of the echo. The echo is amplified using the aligned gain profile and the amplified echo is digitized before being attenuated using the aligned gain profile. An actual time of arrival of the echo is calculated based on the attenuated digitized echo. The gain profile is re-aligned with the attenuated digitized echo according to the actual time of arrival of the echo. The attenuated digitized echo is re-amplified using the re-aligned gain profile to obtain a gain-corrected echo.

A method for analyzing dynamic mode change of an anisotropic material includes performing modal analysis of a first physical force applied to an isotropic material specimen and a first vibration signal collected from the isotropic material specimen, acquiring a first modal parameter of the isotropic material specimen, based on the modal analysis result, performing modal analysis of a second physical force applied to the anisotropic material specimen and a second vibration signal collected from the anisotropic material specimen, acquiring a second modal parameter of the anisotropic material specimen, based on the modal analysis result, acquiring a modal assurance criterion (MAC) for each mode of the anisotropic material specimen, based on the first and second modal parameters, and acquiring each similar mode of the anisotropic material specimen to each mode of the isotropic material specimen.

This disclosure relates generally to a method and system for determining viscosity information of fluids. The present disclosure utilizes an intensity modulated continuous wave (CW) laser diode-based PA sensing method to obtain a continuous wave photoacoustic (CWPA) spectra. Through this CWPA spectra, a full width half maximum (FWHM) and a spectral area is determined to obtain the information about the viscosity of fluids. Although, the CWPA based sensing technique is used for distinguishing different types of abnormalities in tissues, so far it is not used for measuring viscosity which is an important thermo-physical property. The viscosity information of the fluids from the normalized Gaussian fitted CWPA spectra is based on a viscosity feature computed from a FWHM, and a spectral area. The viscosity feature improves the good of fit parameter (R.sup.2) significantly to 0.98 as compared to the traditional only FWHM based viscosity determination for which R.sup.2 is 0.91.

Method and system are disclosed for characterizing and quantifying composite laminate structures. The method and system take a composite laminate of unknown ply stack composition and sequence and determine various information about the individual plies, such as ply stack, orientation, microstructure, and type. The method and system distinguishes between weave types that exhibit similar planar stiffness behaviors, but which produce different failure mechanisms. Individual ply information then is used to derive the laminate bulk properties from externally provided constitutive properties of the fiber and matrix, including extensional stiffness, bending-extension coupling stiffness, bending stiffness, and the like. The laminate bulk properties are then used to generate a probabilistic failure envelope for the composite laminate. This provides the ability to perform non-destructive QA to ensure that individual lamina layup was accomplished according to specifications, and results are used to identify numerous laminate properties beyond purely structural ones.