447 results about "Rayleigh Light Scattering" patented technology

The invention discloses an optical frequency domain reflection strain sensing method based on the combination of phase demodulation and cross-correlation, and the method comprises the steps: collecting backward Rayleigh scattering signals before and after the strain of a to-be-measured optical fiber, and extracting the phase information of a reference signal and a measurement signal through Fourier transform; a cross-correlation algorithm is combined to match a reference signal and a measurement signal at the same position of the optical fiber, and a dislocation phenomenon on a distance domain is corrected; calculating the relative phase of the matched reference signal and measurement signal at the same position, and performing phase unwrapping; distinguishing a fiber grating area and a non-grating area, and performing continuous correction on phase data by adopting a linear regression fitting algorithm so as to eliminate jump errors; on the basis of the differential relative phase, a window where the sudden change position is located is determined according to the window width obtained in the cross-correlation algorithm, segmented assignment is conducted on the strain of the window, and finally complete strain field distribution data are output. According to the method, the stability, the anti-interference capability and the measurement reliability of the phase demodulation method are improved.

The invention discloses an optical fiber distributed sound wave sensing device based on double chirped pulses, which relates to the technical field of distributed optical fiber sensing and comprises a laser module (1), a chirped pulse modulation module (2), a sensing optical fiber module (3) and a Rayleigh scattering signal separation and receiving module (4), laser generated by the laser module passes through the chirped pulse modulation module to obtain double chirped pulse signals with different frequency bands, excites Rayleigh scattering signals in the sensing optical fiber module and inputs the Rayleigh scattering signals to the Rayleigh scattering signal separation and receiving module for signal separation and demodulation. The sensing optical fiber is inquired through double chirped pulses of different frequency bands, two Rayleigh scattering signals are excited to achieve a wide range and high sensitivity, the advantages of the two signals are combined through an adaptive filtering algorithm, the dynamic range of distributed sound wave detection is improved by one order of magnitude, and the detection accuracy is improved. The acquisition of large chirp bandwidth Rayleigh scattering signals is realized at a low sampling rate, and a distributed sound wave sensing technology with a large dynamic range is realized.

The invention discloses an overhead line system cable state real-time monitoring method and sensing system based on distributed optical fiber sensing. The Mach-Zehnder interference and phi-OTDR fusion type distributed optical fiber sensing system comprises a first light source, a second light source, a Mach-Zehnder interferometer, a phi-OTDR and a data acquisition and processing module. Raman amplifiers are arranged at the two ends of the Mach-Zehnder interferometer, so that the sensing distance is prolonged; the optical fiber sensing system extracts an interference optical signal and a backward Rayleigh scattering optical signal corresponding to a fault event after phase modulation when the fault event occurs; then processing the extracted backward Rayleigh scattering light signal to obtain intensity change information of a fault event, and demodulating the position of the fault event; and sending the two-dimensional optical signal into a pre-trained Swin Transform network model to extract a time domain feature, a frequency domain feature and a spatial domain feature, and identifying the type of a fault event through a classifier.

The invention discloses a signal-to-noise ratio improvement method based on a multi-core optical fiber dual-channel distributed acoustic sensing system, and the method comprises the steps: carrying out the light splitting of light emitted by a narrow linewidth laser through a first coupler C1, enabling one path of light to generate a pulse signal through an acoustic optical modulator (AOM), enabling the other path of light to pass through a second coupler C2, and enabling the other path of light to pass through a second coupler C1; the pulse light is divided into two beams of transmission light, the two beams of transmission light are injected into a connected sensing optical fiber through two groups of erbium-doped optical fiber amplifiers (EDFA), two groups of filters, two groups of circulators and a fan-in coupler Fan-in Coupler, and the pulse light is subjected to backward Rayleigh scattering in the sensing optical fiber; based on a dual-channel DAS system, a multi-core optical fiber is used as a sensing optical fiber, three cores and four cores of the multi-core optical fiber are connected in series to form two sensing channels, seven-core space division signals are multiplexed, the equivalent self-noise pressure suppression effect of the seven-core space division signals is analyzed, after noise correlation is removed through a time domain dislocation-frequency domain phase shift method, the signal-to-noise ratio gain can be increased to 8.65 dB, and the signal-to-noise ratio gain can be increased to 8.65 dB. And the detection capability of the system on low-frequency weak signals can be improved.

The invention discloses a conveyor carrier roller online monitoring method and device and electronic equipment. The method comprises the following steps of: firstly, acquiring a sound wave vibration signal generated in real time when the carrier roller of the conveyor moves; wherein the sound wave vibration signal is obtained based on reverse Rayleigh scattering light in the optical fiber; performing feature extraction from the sound wave vibration signal to obtain an energy feature value of each frame; performing normalization processing on the energy characteristic value to obtain a target characteristic value; judging whether the target characteristic value exceeds a preset threshold value or not: if the target characteristic value exceeds the preset threshold value, inputting the target characteristic value into a pre-constructed target neural network model, so that the target neural network model outputs a fault type corresponding to the target characteristic value; therefore, online monitoring of the conveyor carrier roller based on optical fiber sensing multi-feature fusion is completed. According to the method, the fault type can be automatically and accurately identified and output, so that the overall performance and safety of the conveyor carrier roller are enhanced.

The invention discloses a photovoltaic panel self-adaptive cleaning system and method based on sand and dust optical thickness monitoring. The photovoltaic panel self-adaptive cleaning system comprises a sand and dust optical thickness monitoring module, a data processing and control module, a cleaning execution module, a power supply module and a remote monitoring module. The sand and dust optical thickness monitoring module is used for monitoring the sand and dust optical thickness AOD of the environment where the photovoltaic panel is located in real time, calculating the AOD by measuring the light intensity attenuation of a specific wavelength, and correcting the atmospheric Rayleigh scattering optical thickness and the gas absorption optical thickness at the same time; the data processing and control module is in communication connection with the sand and dust optical thickness monitoring module and used for receiving the AOD data and comparing the AOD data with a preset dust retention threshold value, and when the AOD value is larger than or equal to the threshold value, a cleaning instruction is generated; and the cleaning execution module is used for receiving the cleaning instruction and executing cleaning operation. Intelligent and self-adaptive control of photovoltaic panel accumulated dust cleaning is achieved, the cleaning opportunity can be adjusted in real time according to the actual sand and dust optical thickness, and the cleaning pertinence and effectiveness are improved.

The invention provides a sensing system fusing optical fiber vibration and acoustic emission, a monitoring method and a device, and relates to the technical field of optical fiber sensing. The device comprises a light source module, a sensing optical fiber, a detection module and a controller, the light source module is used for respectively emitting modulation pulse light for vibration monitoring and continuous wave laser for acoustic emission monitoring; the sensing optical fiber is arranged along a monitored structure or area, and at least one optical fiber acoustic emission sensing head is connected to the optical fiber in series. The detection module collects Rayleigh scattering light and beat frequency signals at all positions in the sensing optical fiber through a circulator and a coherent light receiver, and optical signals are converted into electric signals; wherein the electric signals comprise vibration electric signals and acoustic emission electric signals; the signal processing unit carries out phase demodulation and envelope analysis processing on the collected vibration electric signals and acoustic emission electric signals so as to obtain vibration waveforms and acoustic emission event space-time information along all points of the optical fiber. According to the invention, a monitoring task fusing vibration and acoustic emission can be accurately completed.

The invention relates to the technical field of wind driven generators, and discloses a wind turbine state monitoring method based on distributed optical fiber sensing. The method comprises the following steps: acquiring historical blade vibration signals and historical optical cable vibration signals to form a historical data set; optimizing the historical data set to obtain an optimized data set, and constructing a vibration transfer function based on optimized data; capturing Rayleigh scattering signals originating from the wind turbine in the optical cable; acquiring a real-time optical cable vibration signal of the optical cable at the wind turbine based on the phase change of the Rayleigh scattering signal; converting the real-time optical cable vibration signal into a real-time blade frequency domain signal based on a vibration transfer function, and restoring the real-time blade frequency domain signal into a real-time blade vibration signal based on inverse Fourier transform; and recognizing the real-time blade vibration signal based on a machine learning algorithm to obtain the real-time operation condition of the blade. According to the method, the working condition of the wind turbine can be monitored without arranging sensors on the blades, and the monitoring cost is reduced.

The invention provides a signal receiving device, a signal transmitting device and an optical fiber sensing device, relates to the technical field of optical fiber sensing, and is used for solving the problems that the requirement for equipment is high when an existing optical fiber sensing device detects Rayleigh scattering and Brillouin scattering at the same time and the like. The signal receiving device comprises a coherent receiver, a radio frequency analog-to-digital conversion unit and a frequency band calculation unit, the coherent receiver is used for obtaining four electric signals with orthogonal phases according to the local oscillation light and the signal light, and the radio frequency analog-to-digital conversion unit converts the four electric signals to obtain two digital signals in a first polarization state and two digital signals in a second polarization state; the frequency band calculation unit is used for calculating the frequency spectrum of the signal light according to the two paths of digital signals of the first polarization state of the signal light and the two paths of digital signals of the second polarization state of the signal light, and the frequency spectrum comprises a phi OTDR signal located at the positive frequency and a BOTDR signal located at the negative frequency.

The invention relates to the technical field of bionic navigation orientation and positioning, in particular to a carrier course angle measuring method based on polarized light imaging in a non-Rayleigh atmosphere. Comprising the steps of real-time sky polarized light imaging, atmospheric polarization mode resolving based on Mueller matrix imaging, non-Rayleigh polarization information interference removal, polarization orientation resolving based on Rayleigh scattering, space projection conversion and sun position information resolving. Alignment information of the sun in a carrier coordinate system is obtained by utilizing a Rayleigh scattering model and actual sky polarization imaging, and then a carrier course angle is obtained according to the orientation of the sun in a local geographic coordinate system, so that an orientation function is realized; meanwhile, the error influence caused by image registration and time-sharing rotation measurement of the multi-view-field polarization detector and the interference of environmental factors on a single point are avoided, the method can adapt to sunny and cloudy weather, is also applicable to cloudy and other non-Rayleigh weather, and is wide in application range.

The invention discloses a distributed OFDR sensing signal demodulation method and system based on local ridge line tracking, relates to the technical field of optical fiber sensing, and is used for solving the problem that a traditional cross-correlation algorithm is difficult to consider robustness and real-time performance at the same time. The method comprises the following steps: respectively processing a reference beat frequency signal of a sensing optical fiber to be measured in a strain-free state and a measurement beat frequency signal of the sensing optical fiber to be measured in a strain state to obtain a reference complex Rayleigh scattering signal and a measurement complex Rayleigh scattering signal containing a plurality of sensing positions along the optical fiber; calculating a cross-correlation function based on the two signals; stacking the cross-correlation functions corresponding to all sensing positions along a distance domain, and constructing a two-dimensional cross-correlation thermodynamic diagram matrix; performing filtering processing and weighting processing on the two-dimensional cross-correlation thermodynamic diagram matrix to obtain an optimal frequency drift distance; and demodulating based on the optimal frequency drift amount to obtain strain distributed along the to-be-measured sensing optical fiber. According to the invention, high-robustness and rapid demodulation of the signal in an application scene with extremely high real-time requirement can be realized.

An optical frequency domain reflectometer with environmental disturbance resistance and large strain measurement capability belongs to the field of distributed optical fiber sensing and comprises an opposite sweep frequency light frequency modulation continuous wave signal generation module, a light splitting device, a modulation device, a circulator, a polarization controller, an optical coupling device, a photoelectric conversion module and a data acquisition and processing module. An optical signal generated by an opposite sweep frequency light frequency modulation continuous wave signal generation module is divided into probe light and local oscillation light through a light splitting device, the probe light is modulated through a modulation device and sent to an optical fiber through a circulator, and a Rayleigh back scattering light signal generated by the optical fiber and the local oscillation light interfere in an optical coupling device to obtain interference light; the photoelectric conversion module mixes beat frequency signals of interference light, and the data acquisition and processing module analyzes and processes the beat frequency signals. According to the invention, the position information of the Rayleigh backscattering point is marked by using the modulated probe light, the Rayleigh scattering signal at the corresponding position is restored, crosstalk between channels is inhibited, and high-precision measurement in a large dynamic range and resistant to environmental disturbance is realized.

The invention discloses a method for monitoring the bonding slip performance and deterioration evolution of an interface in a combined member, and the method comprises the following steps: carrying out the degreasing cleaning pretreatment of a section with relatively high rigidity in a to-be-detected combined member, and obtaining a pretreated section; distributed optical fiber sensors based on Rayleigh scattering are arranged on the surface of the pretreated profile in the direction of measured cohesive force; bonding the profile on which the distributed optical fiber sensors are arranged with a to-be-detected matrix through an adhesive to prepare a combined component; a uniaxial tensile test is conducted on the combined component, distribution and evolution of steel bar strain in the test process are recorded through a distributed optical fiber sensor, distribution and evolution of the bond-slip relation are obtained, the local bond-slip relation can be researched, and the applicability and precision of a bond-slip model are improved; before uniaxial stretching, working conditions are applied to the composite structure to degrade the structure, and the influence of degradation on the bonding performance of the composite structure can be evaluated.

The invention provides an atmospheric correction method and device for a solar zenith angle lower coastal water area radiation signal. The method provided by the invention comprises the following steps: generating noon remote sensing reflectivity satellite data based on observation data of a coastal water area by utilizing an ultraviolet-near infrared atmospheric correction combination model; utilizing a maximum cross correlation method to obtain adjusted noon remote sensing reflectivity satellite data based on the spatial resolution and the time resolution of the data; calculating a Rayleigh correction radiance based on a Rayleigh scattering lookup table corresponding to the observation data, and matching the Rayleigh correction radiance with the adjusted noon remote sensing reflectivity satellite data based on time information and position information to obtain a training set; and inputting the to-be-corrected coastal water area radiation signal into the model trained based on the training set, and determining the off-water radiance of the radiation signal. According to the method and the device provided by the invention, atmospheric correction of a coastal water area radiation signal at a high solar zenith angle is realized for a turbid coastal water area.

The invention relates to a non-intrusive monitoring electric power optical fiber abnormity identification and positioning method and system, and the method comprises the following steps: enabling an optical fiber to generate leakage light through a clamping coupler, converting a leakage light signal into an electric signal through a photoelectric detector, converting the photoelectric signal into a digital signal through an analog-to-digital converter, and transmitting the digital signal to a processor; when the digital signal has fluctuation greater than a preset value, marking the optical fiber line as an abnormal line; the optical fiber measurement module is communicated with the abnormal optical fiber line through the optical switch switching module, and a backward Rayleigh scattering signal in the abnormal line is measured; carrying out noise reduction on a back Rayleigh scattering signal in the abnormal line by using wavelet transform; performing abnormal point positioning according to a mutation point on the backward Rayleigh scattering signal after noise reduction, and identifying an abnormal type through a support vector machine model optimized by a grey wolf algorithm; and merging the abnormal points and the abnormal types in the optical fiber line, transmitting the merged abnormal points and abnormal types to a cloud through a data transmission port, and sending out an optical fiber line abnormal early warning.

The invention discloses a blue-green algae type discrimination method based on a three-dimensional fluorescence spectrum. The method comprises the following steps: S0, obtaining a to-be-detected sample; the method comprises the following steps: S1, acquiring original three-dimensional fluorescence spectrum data; s2, preprocessing the original three-dimensional fluorescence spectrum data; rayleigh scattering and Raman scattering in the original three-dimensional fluorescence spectrum are removed, and smooth denoising is carried out on the original three-dimensional fluorescence spectrum; s3, spectral features are extracted based on a parallel factor-peak ratio method, and spectral feature vectors are obtained; and S4, carrying out missing value supplement and data standardization processing on the obtained spectral feature vectors, inputting the processed feature vectors into a trained LightGBM multi-classifier, outputting probabilities by a classification model, and selecting a category with the maximum probability. According to the method, the distribution mechanism of the blue-green algae fluorescent pigment is combined, and the fluorescent component characteristics and the relative content characteristics of the fluorescent components of the blue-green algae are comprehensively considered, so that the three-dimensional fluorescence spectrum information of the blue-green algae sample can be more comprehensively, completely and meticulously represented, and the variety discrimination of different blue-green algae with smaller difference is realized.

The invention provides a distributed optical fiber sensing integrated system and an implementation method, the system comprises a sending end, a sensing receiving end, a communication receiving end and a transmission link unit, the sending end is used for generating an LFM-PSK sensing integrated optical signal and a path of LFM optical signal; the sensing receiving end is used for carrying out matched filtering on the LFM-PSK sensing integrated optical signal and a Rayleigh scattering signal returned by the transmission link unit so as to detect and analyze the change of phase information of a transmission optical fiber; and the communication receiving end is used for performing heterodyne correlation detection on the LFM-PSK sensing integrated optical signal and the other path of LFM optical signal so as to restore a PSK communication signal, and then acquiring the original service signal based on the PSK communication signal. Compared with the prior art, the system has the advantages that the signal-to-noise ratio of a sensed signal in a strong noise interference environment is higher, and the sensing performance is better.

The invention discloses a subway anti-intrusion monitoring method and device based on a common communication optical cable, and relates to the technical field of urban rail transit safety monitoring, an intrusion monitoring device based on an optical cable monitoring piece is adopted to monitor subway intrusion behaviors, and the optical cable monitoring piece of the intrusion monitoring device is arranged along a subway tunnel. One end of the optical cable monitoring piece is connected with the optical signal generator, and the other end is in communication connection with the signal processing unit through the optical fiber sensing module and the data acquisition module; according to the invention, the physical state along the optical cable can be monitored in real time by using the phase-sensitive optical time domain reflection technology; the signal processing unit obtains optical fiber length change characteristics by utilizing an electric field expression of a Rayleigh scattering signal and phase change analysis, and then can efficiently and intelligently analyze and output intrusion types and probabilities based on the optical fiber length change characteristics through a deep learning model; and identifying the potential safety hazard of the subway tunnel by analyzing micro vibration, temperature change and stress change along the optical cable.

The invention discloses a seismic data acquisition device based on a ground 3C-DAS optical cable and an acquisition method thereof, is applied to the field of seismic exploration, and aims to solve the problems of high layout cost, too long construction time and low operation efficiency of an existing ground three-component detector. According to the method, a 3C-DAS armored optical cable is buried under a shallow earth surface in a parallel or orthogonal mode, a ground multichannel low-frequency DAS modulation-demodulation instrument collects phase data of Rayleigh scattering light reflected back from the 3C-DAS armored optical cable and carries out modulation-demodulation processing, and high-density distributed three-component seismic data distributed along the 3C-DAS armored optical cable is obtained; according to the system, high-density distributed three-component ground seismic data along the armored optical cable can be rapidly and efficiently acquired at low cost; the invention also provides a processing method for the collected high-density distributed three-component ground seismic data, an analysis method for a shallow surface velocity structure with high spatial resolution, and an inversion imaging method for longitudinal waves, transverse waves and surface waves.

The invention relates to a damaged point monitoring system and method for a hollow-core optical fiber, computer equipment, a medium and a product, and relates to the technical field of telecommunication operation and maintenance. The system comprises a sensing sending module and a sensing receiving module, wherein the sensing transmitting module is used for transmitting a target optical pulse coding signal corresponding to a current monitoring mode to a to-be-detected hollow-core optical fiber; the monitoring mode comprises an on-line monitoring mode and an off-line monitoring mode, and the wavelength bands of the target optical pulse coded signals corresponding to the on-line monitoring mode and the off-line monitoring mode are different; and the sensing receiving module is used for receiving the backward Rayleigh scattering light reflected by the to-be-detected hollow-core optical fiber and positioning a damaged point of the to-be-detected hollow-core optical fiber according to the backward Rayleigh scattering light and the layout path information of the to-be-detected hollow-core optical fiber. The system can accurately position the damaged point of the hollow-core optical fiber.

The invention provides a multi-scale constructed high-transparency stable super-hydrophobic coating and a preparation method thereof, multi-scale coupling is introduced to prepare a transparent super-hydrophobic surface, that is, a micron-sized hollow particle and nano-particle collaborative accumulation mode is adopted, and the micron-sized hollow particles can play a supporting role while ensuring the transparency of the micron-sized hollow particles; the diameter of the coupled nanoparticles is about dozens of nanometers and is smaller than one tenth of the wavelength of visible light, so that the influence of Mie scattering and Rayleigh scattering can be reduced to the greatest extent, and high transparency is kept. Meanwhile, the stability of the surface is optimized, it is ensured that the super-hydrophobic surface can achieve the excellent antifouling effect in practical application, and the transparency and mechanical strength of the material are not sacrificed.

The invention discloses polybutadiene latex, a preparation method thereof and transparent ABS (Acrylonitrile Butadiene Styrene) resin. In the preparation process of the polybutadiene latex, the emulsifier is additionally added at a relatively high conversion rate to promote the reaction to generate part of latex particles with small particle sizes. When the latex prepared by the method is used for further preparing the transparent ABS resin, since the latex with the particle size of 30-70nm has a rayleigh scattering effect to a certain extent, a small amount of blue light can be scattered, so that the yellow index of the resin is reduced, and the prepared transparent ABS has better hue.

The invention discloses a dike underwater piping positioning system based on distributed optical fiber vibration sensing, and relates to the technical field of positioning systems, and the dike underwater piping positioning system comprises a distributed optical fiber vibration sensing host which is used for transmitting a laser pulse to a sensing optical cable and demodulating a backward Rayleigh scattering signal; the multi-mode sensing optical cable is arranged along the dike underwater area and comprises a vibration sensing optical fiber and a temperature sensing optical fiber; the data processing module is used for executing time-space synchronous analysis of the vibration signal # imgabs0 # and the temperature signal # imgabs1 #; and the data processing module comprises a multi-modal feature fusion unit, and the multi-modal feature fusion unit is used for generating a combined feature factor # imgabs4 # by fusing the intensity # imgabs2 # and the temperature change rate # imgabs3 # of the vibration signal and carrying out weight distribution. According to the invention, through the technical closed loop of multi-mode sensing, intelligent layout and deep learning, the technical blank of the existing distributed optical fiber monitoring system in the aspects of early recognition, accurate positioning and intelligent early warning of underwater piping is filled.

The invention discloses a carbon dioxide formation leakage monitoring device and method based on distributed optical fiber sensing. The device comprises a simulated formation, an injection system and a DTS system. A thermal insulation device, a thermometer and a production well system are mounted on the simulated stratum; the injection system is used for injecting carbon dioxide and liquid into the simulated stratum; the DTS system comprises a light source assembly, an optical fiber group, a detection assembly and a data acquisition and processing unit which are connected in sequence; a plurality of monitoring points of the optical fiber group are arranged, and the plurality of monitoring points are arranged in the simulated stratum at intervals; the detection assembly is used for detecting Rayleigh scattering frequency shift and Rayleigh backscattering light intensity and phase in the optical fiber group, and the data acquisition and processing unit is used for acquiring signals output by the detection assembly and performing data processing and analysis. According to the invention, fine monitoring and continuous monitoring of carbon dioxide stratum leakage can be realized, the environmental interference resistance is high, and the installation and maintenance cost is low.

The invention discloses a three-phase common-box GIL vibration state detection method and device based on optical fiber sensing, and belongs to the technical field of high voltage and insulation, and the method comprises the steps: 1, uniformly winding one end of an optical fiber on the surface of a to-be-detected three-phase common-box GIL, and selecting a pulse signal generator according to the characteristic frequency of a to-be-detected signal, transmitting a pulse detection optical signal to an optical fiber wound on the surface of the GIL; 2, collecting a Rayleigh scattering light signal containing the GIL vibration signal under the action of the pulse detection light signal, and converting the Rayleigh scattering light signal containing the GIL vibration signal into a waveform signal containing the GIL vibration signal; and step 3, debugging and de-noising the waveform signal containing the GIL vibration signal to obtain a signal reflecting the vibration state of the three-phase common-box GIL. According to the invention, the change of the GIL vibration signal is reflected by using the scattered light signal in the optical fiber, and the device can be applied to the on-line monitoring of the insulation defect and partial discharge in the three-phase common-box GIL equipment by replacing the pulse signal generator.

The invention provides a remote sensing estimation method for the chlorophyll a concentration of a river, and belongs to the technical field of hydrological remote sensing, and the method comprises the following steps: during a satellite transit period, sampling at a plurality of point locations of the river to obtain measured data, obtaining satellite data, carrying out Rayleigh scattering correction on the satellite data to obtain reflectivity after Rayleigh correction, and calculating the chlorophyll a concentration of the river; the method comprises the following steps: screening measured data, establishing an XGBoost model, training the model data, and calculating the chlorophyll a concentration of the river by using the trained XGBoost model. The invention relates to a river chlorophyll a concentration remote sensing estimation method by using Landsat and machine learning. According to the method, based on actually measured chlorophyll a concentration data of the Pearl River basin, a machine learning model capable of estimating the river chlorophyll a concentration is established by using Landsat data after Rayleigh scattering correction, a new thought is provided for monitoring river water quality, and powerful technical support is provided for river eutrophication monitoring and water environment protection and treatment.

The application belongs to the technical field of distributed optical fiber sensing, and particularly relates to a long-distance distributed optical fiber broadband acoustic vibration sensing system. The application utilizes the same laser to transmit and generate back Rayleigh scattering light and interference light in the same sensing optical fiber, and further constructs a distributed optical fiber acoustic vibration sensing system combined with Φ-OTDR and MZI, which comprehensively utilizes the performance advantages of both, utilizes a very simplified optical system scheme, realizes the function fusion of the two sensing structures on one sensing optical fiber, reduces the resource waste caused by the transmission of sensing signals by different sensing optical cables respectively, maximizes the optical fiber resource utilization rate, and reduces the system cost; utilizes a frequency division multiplexing demodulation scheme in the digital domain, expands the frequency response range on the basis of ensuring the high positioning accuracy of the system, realizes the simultaneous detection of the two systems by a single core, simultaneously realizes the high positioning accuracy and the continuous non-blind area detection in the broadband frequency range, and improves the reliability.

The invention discloses a weak light detector nonlinear measurement and correction method and system based on Rayleigh scattering, and belongs to the technical field of optical measurement. A weak light detector is an optical signal device used for detecting extremely low light intensity, and when the weak light detector works under the low light intensity condition, nonlinear response is often shown, and the accuracy and the stability of a measurement result can be remarkably influenced. Therefore, non-linear correction is crucial to guarantee of reliability and repeatability of measured data. According to the invention, a Rayleigh scattering-based weak light detector nonlinear measurement system is established, the incident laser power is measured by using a high-precision thermoelectric detector, and then the scattered light power is measured by using a weak light detector-photomultiplier. Different laser incident powers are set to obtain Rayleigh scattering signals and incident light powers under different working conditions, and the scattered light power is corrected by using an incident laser power measurement value.

The cloud layer inversion method of the laser ceilometer comprises the following steps: acquiring original measurement data of the laser ceilometer; dividing the original measurement data into low-altitude data and high-altitude data according to a preset segmentation threshold value; optimizing the low-altitude data according to a Mie-Rayleigh scattering laser radar equation to obtain low-altitude optimized data; comparing the low-altitude optimization data with a preset low-altitude threshold value, and determining the height of a low-altitude cloud layer according to a comparison result; segmenting the high-altitude data to obtain a plurality of data segments, and performing data validity screening on each data segment to extract a high-altitude valid data segment; calculating an effective median value and a data fluctuation quantity of each effective data segment; calculating a dynamic threshold according to all data fluctuation quantities; optimizing the high-altitude data to obtain high-altitude optimized data; and comparing the high-altitude optimization data with a dynamic threshold value, and determining the height of the high-altitude cloud layer according to a comparison result. According to the invention, the accuracy of the inversion result can be effectively improved.

The invention provides a power distribution communication network optical cable fault prediction method and system based on machine learning. The method comprises the following steps: collecting Rayleigh scattering signals of a plurality of monitoring points along an optical cable; performing unsupervised learning on the optical cable adaptive reconstruction model, and calculating a reconstruction error matrix and an abnormal cumulative metric; constructing an optical cable network diagram, calculating a fault propagation probability matrix, predicting a future optical cable health index, and obtaining a future health index matrix; establishing an environment influence matrix, and adopting an optical cable environment adaptive filtering model; and based on the health index and the fault confidence coefficient matrix after filtering optimization, optical cable maintenance priority scores are calculated and sorted, and a self-adaptive inspection and maintenance strategy is formulated. According to the invention, high-precision monitoring, fault propagation prediction and environmental adaptability optimization of the health state of the optical cable are realized, and the intelligent level of operation and maintenance of the optical cable is improved.