Abstract: A method and a device for structural damage detection in a nonlinear system are provided. The method includes: applying an excitation force to a specimen to be detected to induce a vibration phenomenon in the specimen to be detected, and performing signal collection on the specimen to be detected by a laser vibrometer to obtain an excitation signal and a response signal; constructing, according to the excitation signal, the response signal and imported order combinations, initial NARX models corresponding to different orders; selecting, based on an Akaike information criterion, a target NARX model corresponding to an optimal order combination; optimizing the target NARX model to obtain a NARX model to be detected; comparing order information of the NARX model to be detected with order information of a benchmark NARX model, and determining, based on an order comparison result, whether there is a defect in the specimen to be detected.

Abstract: A defect detection method and device based on nonlinear system identification are provided. The defect detection method includes: performing, by a modal force hammer, hammer excitation on a test specimen according to a test schedule to generate an excitation signal and a response signal; acquiring, by a laser vibrometer, the excitation signal and the response signal; performing parameter calculation on the excitation signal and the response signal to obtain model parameters; constructing an initial Hammerstein model based on the model parameters; optimizing the initial Hammerstein model to obtain a Hammerstein model of the test specimen; adjusting the Hammerstein model of the test specimen by using a cross-validation method; perform defect determination based on the Hammerstein model of the test specimen adjusted and a pre-constructed template specimen model to obtain a determination result, and determining whether the test specimen is defective based on the determination result.

Abstract: A method for extracting and analyzing spatial information of a control and protection zone of rail transit with multiple threshold constraints, including the following steps: 1, performing format conversion on a data file and extracting a plurality of coordinate points; 2, selecting key points from the plurality of coordinate points for data simplification to obtain a simplified limit line, a simplified outer structure edge line and a simplified boundary line of construction; 3, programming the simplified limit line, the simplified outer structure edge line, and the simplified boundary line of construction, calling a database, and reading data therefrom for spatial relationship comparison; 4, determining whether the construction of a rail-involved construction project intrudes into a control and protection zone of rail transit according to a result of the spatial relationship comparison, thus completing the extraction and analysis of the spatial information of the control and protection zone of rail transit.

Abstract: The present invention provides a point cloud data acquisition method and device under a situation of no GNSS signal. The method comprises: re-sampling line data acquired from a topographic map to obtain discrete line data; generating a full-second PPS pulse in a simulating manner; counting by using a distance measuring instrument, sampling the count, when it is detected that the full-second PPS pulse is received, calculating position information at a current moment; simulating a GNSS satellite protocol according to the position information at the current moment; parsing the GNSS satellite protocol by using a point cloud data acquisition module to complete time synchronization, and controlling a LiDAR to acquire point cloud data; parsing the GNSS satellite protocol by using an inertial measurement module, and recording attitude determination positioning data in real time to generate POS data; and optimizing the POS data to obtain accurate point cloud data.

Abstract: A method for extracting and analyzing spatial information of a control and protection zone of rail transit with multiple threshold constraints, including the following steps: 1, performing format conversion on a data file and extracting a plurality of coordinate points; 2, selecting key points from the plurality of coordinate points for data simplification to obtain a simplified limit line, a simplified outer structure edge line and a simplified boundary line of construction; 3, programming the simplified limit line, the simplified outer structure edge line, and the simplified boundary line of construction, calling a database, and reading data therefrom for spatial relationship comparison; 4, determining whether the construction of a rail-involved construction project intrudes into a control and protection zone of rail transit according to a result of the spatial relationship comparison, thus completing the extraction and analysis of the spatial information of the control and protection zone of rail transit.

Abstract: The present invention provides a point cloud data acquisition method and device under a situation of no GNSS signal. The method comprises: re-sampling line data acquired from a topographic map to obtain discrete line data; generating a full-second PPS pulse in a simulating manner; counting by using a distance measuring instrument, sampling the count, when it is detected that the full-second PPS pulse is received, calculating position information at a current moment; simulating a GNSS satellite protocol according to the position information at the current moment; parsing the GNSS satellite protocol by using a point cloud data acquisition module to complete time synchronization, and controlling a LiDAR to acquire point cloud data; parsing the GNSS satellite protocol by using an inertial measurement module, and recording attitude determination positioning data in real time to generate POS data; and optimizing the POS data to obtain accurate point cloud data.