An underground pipeline corridor leakage gas identification system based on infrared spectroscopy analysis

Abstract

The present invention relates to the field of gas detection technology, and discloses an underground pipe gallery leak identification system based on infrared spectroscopy analysis, comprising: an acoustic sensor unit that passively monitors pipe gallery acoustic signals and generates a wake-up command and azimuth information; an infrared spectroscopy analysis module that transmits an infrared light beam with a specific wavelength combination to the estimated leakage sector based on the azimuth information and receives a return light signal to generate spectral data; and a control processing unit that analyzes the spectral data and coordinates with the azimuth information to determine and confirm a leakage event. The present invention achieves an energy-efficient mode innovation from continuous scanning to event-driven through the collaborative mechanism of acoustic triggering and infrared directional detection. Combining differential spectroscopy technology with spatial coding logic verification, it significantly improves the accuracy and response speed of identifying trace leaks in complex environments.

Description

Technical Field

[0001] The present invention relates to an underground pipe gallery gas leakage identification system based on infrared spectrum analysis, belonging to the technical field of intelligent monitoring of underground pipe gallery gas leakage. Background Art

[0002] In the field of gas detection technology, underground pipeline corridor gas leak monitoring primarily relies on infrared spectroscopy. Current mainstream systems identify gases by actively emitting infrared beams and detecting characteristic absorption patterns, which can meet basic monitoring needs in conventional environments. However, when applied to actual pipeline corridor environments, these solutions gradually become subject to technical limitations:

[0003] 1. The conflict between energy efficiency and coverage: To achieve comprehensive monitoring, existing systems typically employ high-density deployment or mechanical scanning mechanisms, significantly increasing equipment complexity and energy consumption. This continuous active detection model is difficult to operate cost-effectively and long-term in long-distance pipe corridors. 2. The balance between environmental interference and recognition accuracy: Temperature and humidity gradients, dust interference, and the coexistence of multi-component background gases within pipe corridors significantly affect infrared spectral characteristics. While algorithmic compensation can partially improve recognition, this increases computational complexity and may introduce new risks of misjudgment. 3. Limitations in early leak response: Existing technologies primarily rely on concentration accumulation after gas diffusion for detection. This inherently delays response to initial trace leaks, making it difficult to provide timely warnings. The industry has attempted various solutions to address these issues, including optimizing sensor sensitivity and refining algorithm models. While these improvements have improved individual performance indicators to some extent, they have failed to fundamentally resolve the inherent conflict between system energy efficiency, environmental adaptability, and timely response. Existing technology systems remain significantly deficient, particularly when it comes to accurately identifying early trace leaks in the complex environment of pipe corridors.

[0004] Therefore, how to build a pipeline corridor gas leakage identification system that can take into account low power operation, strong anti-interference ability and fast response characteristics has become the technical problem to be solved by the present invention. Summary of the Invention

[0005] The present invention provides an underground pipe gallery leakage gas identification system based on infrared spectroscopy analysis, the main purpose of which is to solve the technical contradiction problem that the existing infrared gas monitoring system is difficult to achieve low power consumption operation, strong anti-interference ability and fast response characteristics in the complex environment of the pipe gallery.

[0006] To achieve the above objectives, the present invention provides an underground pipe gallery gas leakage identification system based on infrared spectroscopy analysis, comprising:

[0007] a) at least one acoustic sensor unit configured to passively monitor acoustic signals in the pipe gallery and, upon detecting a signal meeting a preset acoustic characteristic of a gas leak, generate a wake-up command and position information indicating a preliminary position of the sound source;

[0008] b) an infrared spectrum analysis module, communicatively connected to the acoustic sensor unit, the infrared spectrum analysis module comprising:

[0009] i. A tunable infrared light source, in response to the wake-up command and according to the position information, emits a sequence of infrared detection beams comprising at least two different wavelengths to the estimated leakage sector, wherein the at least two different wavelengths correspond to characteristic absorption peaks of at least two key target gases;

[0010] ii. an infrared detector for receiving infrared light returned from the estimated leakage sector and generating spectral data of the target area comprising at least two different wavelengths of infrared light intensity;

[0011] c) a control processing unit connected to the acoustic sensor unit and the infrared spectrum analysis module, configured to:

[0012] i based on the position information, controlling the emission direction of the tunable infrared light source and / or the wavelength combination contained in the infrared detection beam sequence;

[0013] ii. Receiving and processing the target area spectral data, by analyzing the attenuation degree of infrared light intensity of at least two different wavelengths, identifying the infrared absorption characteristics of potential gas leaks;

[0014] iii. When the infrared absorption characteristics of at least one potential leaking gas that meets the preset absorption intensity threshold are identified, and the type of the potential leaking gas matches the preset pipeline type within the estimated leakage sector indicated by the position information, the leakage event is confirmed and an alarm signal is output.

[0015] In a preferred embodiment, the acoustic sensor unit includes an acoustic anisotropic microstructure sensor array, and the control processing unit is further configured to calculate the two-dimensional coordinate information or three-dimensional coordinate information of the sound source based on the time delay or intensity difference between the acoustic signals received by different sensors in the array to optimize the orientation information and determine the estimated leakage sector.

[0016] In a preferred embodiment, the infrared spectrum analysis module is further configured to instruct the tunable infrared light source to emit the same infrared detection beam sequence to at least one background reference area confirmed by the acoustic sensor unit and currently having no leakage acoustic signal at the same time or after emitting the infrared detection beam sequence to the estimated leakage sector, so as to obtain background spectrum data; and the control processing unit is further configured to calculate the intensity difference between the target area spectrum data and the background spectrum data at the corresponding wavelength to obtain the differential spectrum, and identify the infrared absorption characteristics based on the differential spectrum.

[0017] In a preferred embodiment, a passive directional reflection structure or a passive directional scattering structure is provided on the inner wall of the tunnel in an area corresponding to the estimated leakage sector. The reflection structure or scattering structure comprises a material with high reflectivity or high scattering rate for infrared light of at least two different wavelengths, and is used to enhance the intensity of the infrared light signal returned to the infrared detector by the estimated leakage sector.

[0018] In a preferred embodiment, the control processing unit is further configured to access a database storing pipeline corridor geographic information system data, which contains pipeline type information in different areas within the pipeline corridor; the control processing unit determines the pipeline corridor area where the potential leakage source is located based on the orientation information, and retrieves the pipeline type contained in the area from the database, and logically matches the identified potential leakage gas type with the retrieved pipeline type. Only when the matching result is consistent, the leakage event is confirmed.

[0019] In a preferred embodiment, the control processing unit calculates the characteristic absorption wavelength of a specific target gas in the differential spectrum Absorbance at ,in, , is the background spectrum at wavelength The light intensity at The target area spectrum at wavelength The light intensity at When the value is greater than the preset leakage judgment threshold, it is preliminarily determined that there is leakage of the target gas.

[0020] In a preferred embodiment, the tunable infrared light source includes a quantum cascade laser array, each laser in the array emits infrared light of a characteristic absorption wavelength of a specific target gas, and the control processing unit selectively activates at least one laser in the array according to the azimuth information.

[0021] In a preferred embodiment, the tunable infrared light source includes a broadband infrared light source and a MEMS Fabry-Perot interferometer, and the control processing unit generates an infrared detection beam sequence including at least two different wavelengths by controlling the transmission wavelength of the interferometer.

[0022] In a preferred embodiment, the preset gas leakage acoustic characteristics include ultrasonic signals in a specific frequency range or acoustic emission signals with a specific time domain envelope, and the acoustic sensor unit includes a piezoelectric ceramic sensor or a MEMS microphone array and is configured with an acoustic filter for filtering out ambient noise.

[0023] In a preferred embodiment, the control processing unit is further configured to generate alarm information including the type of leaked gas and the estimated leakage location after confirming the leakage event, and send the alarm information to the remote monitoring platform.

[0024] Compared with the background technology problems, the beneficial effects of the present invention are:

[0025] 1. To address the energy efficiency bottleneck caused by continuous scanning in long-distance monitoring scenarios of underground pipeline corridors, this system achieves an energy efficiency innovation from active search to event-driven mode through the coordinated mechanism of acoustic triggering and infrared directional detection. After capturing the transient acoustic characteristics of the initial leak in the passive monitoring state, the acoustic sensor array accurately locks the target sector and wakes up the infrared module for directional scanning. This physical triggering mechanism effectively avoids the energy waste in the ineffective area of ​​​​the traditional solution. The wavelength combination of the tunable light source dynamically matches the absorption peak of the estimated leaking gas. Combined with the secondary focusing of the light beam path by the passive reflection structure on the inner wall of the pipeline corridor, the trace leaking gas can generate a characteristic absorption signal within a limited optical path, fundamentally establishing a technical path for high-sensitivity detection under low power consumption conditions.

[0026] 2. Faced with the combined challenges of complex environmental interference and trace absorption of target gases, the system significantly improves the specificity of feature recognition through the dual guarantees of differential spectroscopy technology and spatial coding logic verification. When the directional infrared beam detects a suspicious absorption peak in the acoustic positioning area, the simultaneous implementation of background reference area spectrum acquisition can effectively remove the baseline drift caused by environmental humidity fluctuations and pipe wall aging. The control unit spatially correlates the attenuation characteristics extracted from the differential spectrum with the sound source orientation information, and then combines it with the logical matching of pipeline medium properties in the GIS database to form a cross-validation mechanism for multi-dimensional criteria. This composite discrimination mode based on physical propagation characteristics and system topology constraints solves the industry problem that traditional single spectral analysis is susceptible to cross-sensitive interference.

[0027] 3. To address the coupling problem of trace gas diffusion and spatial positioning in the early stages of a leakage event, a collaborative positioning system combining acoustic anisotropy sensing and infrared beam spatial modulation was constructed. The microstructured sensor array obtains the vector position of the leakage source through time-delay analysis of the acoustic wave propagation path, and guides the tunable light source to emit a wavelength-coded detection sequence to the target sector. This acoustic event-driven beam spatial modulation technology ensures that the infrared spectrum acquisition process naturally carries spatial attribute information of the leakage source. Combined with the constraints of the corridor structure on the beam propagation path, it achieves simultaneous and precise analysis of gas composition identification and leakage source positioning, breaking through the response delay bottleneck caused by the separation of chemical detection and physical positioning in traditional solutions.

[0028] 4. To address the risk of false alarms caused by the coexistence of multiple types of pipelines in underground pipeline corridors, the system has constructed an environmentally self-consistent leakage verification system through a logical coupling mechanism between gas absorption characteristics and pipeline spatial properties. When the infrared spectrum identifies the absorption characteristics of a specific gas, the control unit indexes the pipeline distribution data in the geographic database based on the acoustic positioning information, verifies the matching degree between the detected gas type and the physical and chemical properties of the preset pipeline medium in the target area, and realizes the verification logic of physical space coupling of chemical fingerprint characteristics and system topology information, effectively suppressing false alarms caused by environmental cross-contamination or misjudgment of pipeline media, and achieving an inherent safety improvement in leakage event identification under complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a working sequence diagram of the underground pipe gallery gas leakage identification system based on infrared spectroscopy analysis of the present invention;

[0030] Figure 2 This is a schematic diagram of the infrared optical path of the underground pipeline gallery gas leakage identification system based on infrared spectroscopy analysis of the present invention;

[0031] Figure 3 This is a gas leakage judgment flow chart of the underground pipeline gallery leakage gas identification system based on infrared spectroscopy analysis of the present invention.

[0032] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0033] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] The present invention provides an infrared spectrum analysis-based system for identifying gas leaks in underground pipe galleries, including:

[0035] a) at least one acoustic sensor unit configured to passively monitor acoustic signals in the pipe gallery and, upon detecting a signal meeting a preset acoustic characteristic of a gas leak, generate a wake-up command and position information indicating a preliminary position of the sound source;

[0036] b) an infrared spectrum analysis module, communicatively connected to the acoustic sensor unit, the infrared spectrum analysis module comprising:

[0037] i. A tunable infrared light source, in response to the wake-up command and according to the position information, emits a sequence of infrared detection beams comprising at least two different wavelengths to the estimated leakage sector, wherein the at least two different wavelengths correspond to characteristic absorption peaks of at least two key target gases;

[0038] ii. an infrared detector for receiving infrared light returned from the estimated leakage sector and generating spectral data of the target area comprising at least two different wavelengths of infrared light intensity;

[0039] c) a control processing unit connected to the acoustic sensor unit and the infrared spectrum analysis module, configured to:

[0040] i based on the position information, controlling the emission direction of the tunable infrared light source and / or the wavelength combination contained in the infrared detection beam sequence;

[0041] ii. Receiving and processing the target area spectral data, by analyzing the attenuation degree of infrared light intensity of at least two different wavelengths, identifying the infrared absorption characteristics of potential gas leaks;

[0042] iii. When the infrared absorption characteristics of at least one potential leaking gas that meets the preset absorption intensity threshold are identified, and the type of the potential leaking gas matches the preset pipeline type within the estimated leakage sector indicated by the position information, the leakage event is confirmed and an alarm signal is output.

[0043] In a preferred embodiment, the acoustic sensor unit includes an acoustic anisotropic microstructure sensor array, and the control processing unit is further configured to calculate the two-dimensional coordinate information or three-dimensional coordinate information of the sound source based on the time delay or intensity difference between the acoustic signals received by different sensors in the array, so as to optimize the orientation information and determine the estimated leakage sector; in actual deployment and operation, the system uses the orientation of the sound source as a reference, dynamically locks the target area through the acoustic trigger mechanism, and guides the infrared spectrum detection module to perform directional sampling. The estimated area can also be regarded as a detection area or a leakage sector, and its expression can be flexibly switched according to the different responsibilities of the module. In the process of information processing, the microstructure array acoustic unit exerts its anisotropic response characteristics to achieve high-precision analysis of the sound source position, effectively ensuring the accuracy of the detection direction selection. Combined with the differential comparison analysis mechanism of the background reference area, the absorption peak of trace gas in a complex interference background is made clearer and more discernible, which are all extended implementation methods known to ordinary technicians in this field.

[0044] In a preferred embodiment, the infrared spectrum analysis module is further configured to instruct the tunable infrared light source to emit the same infrared detection beam sequence to at least one background reference area confirmed by the acoustic sensor unit and currently having no leakage acoustic signal at the same time or after emitting the infrared detection beam sequence to the estimated leakage sector, so as to obtain background spectrum data; and the control processing unit is further configured to calculate the intensity difference between the target area spectrum data and the background spectrum data at the corresponding wavelength to obtain the differential spectrum, and identify the infrared absorption characteristics based on the differential spectrum.

[0045] In a preferred embodiment, a passive directional reflection structure or a passive directional scattering structure is provided on the inner wall of the tunnel in an area corresponding to the estimated leakage sector. The reflection structure or scattering structure comprises a material with high reflectivity or high scattering rate for infrared light of at least two different wavelengths, and is used to enhance the intensity of the infrared light signal returned to the infrared detector by the estimated leakage sector.

[0046] In a preferred embodiment, the control processing unit is further configured to access a database storing pipeline corridor geographic information system data, which contains pipeline type information in different areas within the pipeline corridor; the control processing unit determines the pipeline corridor area where the potential leakage source is located based on the orientation information, and retrieves the pipeline type contained in the area from the database, and logically matches the identified potential leakage gas type with the retrieved pipeline type. Only when the matching result is consistent, the leakage event is confirmed.

[0047] In a preferred embodiment, the control processing unit calculates the characteristic absorption wavelength of a specific target gas in the differential spectrum Absorbance at ,in, , is the background spectrum at wavelength The light intensity at The target area spectrum at wavelength The light intensity at When the value is greater than the preset leakage judgment threshold, it is preliminarily determined that there is leakage of the target gas.

[0048] In a preferred embodiment, the tunable infrared light source includes a quantum cascade laser array, each laser in the array emits infrared light of a characteristic absorption wavelength of a specific target gas, and the control processing unit selectively activates at least one laser in the array according to the azimuth information.

[0049] In a preferred embodiment, the tunable infrared light source includes a broadband infrared light source and a MEMS Fabry-Perot interferometer, and the control processing unit generates an infrared detection beam sequence including at least two different wavelengths by controlling the transmission wavelength of the interferometer.

[0050] In a preferred embodiment, the preset gas leakage acoustic characteristics include ultrasonic signals in a specific frequency range or acoustic emission signals with a specific time domain envelope, and the acoustic sensor unit includes a piezoelectric ceramic sensor or a MEMS microphone array and is configured with an acoustic filter for filtering out ambient noise.

[0051] In a preferred embodiment, the control processing unit is further configured to generate alarm information including the type of leaked gas and the estimated leakage location after confirming the leakage event, and send the alarm information to the remote monitoring platform.

[0052] Example 1: In this example, a typical underground integrated pipeline corridor is selected as the test environment. The pipeline corridor contains various types of pipelines such as gas pipelines, communication optical cables and sewage pipes, and has typical structural features such as dual channels, long distances and multiple branches. It is intended to verify the leakage identification system based on the collaborative mechanism of infrared spectroscopy and acoustic positioning described in the present invention, and its identification effectiveness and engineering feasibility under complex working conditions. The system as a whole follows the integrated deployment principle of node self-sustaining, no mechanical scanning, and module collaboration. The control processing unit realizes functional integration through an embedded edge intelligent platform. The power consumption of the whole system is controlled within 20 watts, which is significantly lower than the traditional infrared spectrum full coverage scanning system.

[0053] When the system is in standby mode, the microstructured acoustic sensor array, deployed at the intersection of the main ventilation channels at the top of the tunnel, operates in a low-power passive monitoring mode. Based on the anisotropic response of acoustic wave propagation, this sensor array is capable of capturing transient abnormal pulse waveforms in the 30kHz to 80kHz frequency range. The sensor array integrates four evenly distributed groups of MEMS acoustic sensing elements, each arranged at a 45-degree angle. Using a time-of-day localization algorithm, the control processing unit calculates the two-dimensional position of the sound source, maintaining a localization error within ±0.5 meters. The system's acoustic signature for leaks includes a high-amplitude, short-duration pulse waveform and a temporal envelope with a characteristic peak width of approximately 0.3 milliseconds. When the acoustic sensor array detects an abnormal signal meeting these characteristics, the system immediately activates the infrared spectroscopy analysis module. The module's integrated tunable infrared light source is a quantum cascade laser array, with each laser corresponding to the characteristic absorption wavelength of a target gas (such as methane, hydrogen sulfide, or ammonia), such as 3.31 microns, 4.05 microns, and 4.25 microns. The infrared pulses emitted by the laser are set to a pulse width of 100 nanoseconds and a repetition rate of 1 kHz. The control circuit precisely controls the direction of the infrared beam based on the location of the sound source, limiting the emission angle to a ±10-degree sector. This ensures targeted illumination of the predicted leak area and avoids false interference caused by redundant detection.

[0054] The infrared beam is reflected toward the target area by a high-reflectivity coating applied to the tunnel's inner wall, increasing the interaction path length between the beam and the leaking gas, thereby improving detection sensitivity. The reflective material used is an aluminum fluoride composite material with a reflectivity greater than 92% in the 3-5 micron band, exhibiting excellent environmental stability and infrared optical performance. The infrared detector, installed on the opposite wall of the tunnel, has a response time of less than 10 nanoseconds and a signal-to-noise ratio exceeding 60 decibels. It receives reflected signals in real time and uploads infrared spectral data containing information on multiple target wavelengths to the control and processing unit. To enhance the reliability of the detection results, after completing data collection in the target area, the system directs the laser to an area confirmed by the acoustic sensor to be free of abnormal acoustic signals. It then transmits an infrared beam with the same wavelength combination and collects the return signal to obtain background spectral data. The control and processing unit calculates the differential spectrum based on the light intensity data at the same wavelength between the target and reference areas to eliminate interference from ambient noise and background gases.

[0055] For example, in methane identification, if the light intensity at a wavelength of 3.31 microns in the target area is 0.53 (normalized value) and the corresponding light intensity in the background area is 0.89, the absorbance is calculated as A = log10 (Ibackground / Itarget) to be approximately 0.23. The system sets a leak detection threshold of 0.15. If the measured value exceeds this threshold and the leak location matches the natural gas pipeline area recorded in the GIS database, the system confirms the leak and generates an alarm message containing the gas type, leak location coordinates (e.g., x = 32.7 meters, y = 8.4 meters), and a confidence level (e.g., 97.2%), which is then sent to the remote monitoring platform. To further reduce false alarms, the control processing unit constructs a joint detection model that comprehensively considers acoustic characteristic parameters (e.g., spectral center frequency, energy distribution), infrared spectral morphology (e.g., absorption peak shape and amplitude), and the degree of matching of pipeline attributes in the GIS database. If this combined score falls below 80%, the event is marked as "requires manual review" and automatic alarms are suspended to avoid false positives.

[0056] The settings of each core parameter in this embodiment are based on engineering verification tests. For example, the tunable laser emission angle of ±10 degrees is the result of achieving the optimal balance between target recognition accuracy and system response time; the absorbance judgment threshold of 0.15 is the optimal threshold determined through large-sample statistical analysis under the coexistence of multiple interfering gases, allowing the system to operate with a false alarm rate below 5% and a false alarm rate below 2%. The matching design of the infrared detector response time and the laser pulse width ensures high temporal resolution while effectively suppressing signal overlap caused by multiple reflections, thereby achieving millisecond-level real-time response capabilities. These are all extended implementation methods known to those skilled in the art.

[0057] Example 2: This example combines Figures 1 to 3 , the implementation of the underground pipeline corridor gas leakage identification system based on infrared spectrum analysis is explained. Figure 1As shown, the entire process starts with the acoustic sensor unit monitoring the acoustic signal. When the acoustic sensor unit monitors the acoustic signal and detects that it meets the acoustic characteristics of a leak, the system executes a conditional branch (represented by the alt box), generates a wake-up instruction and orientation information, and sends the wake-up instruction and orientation information to the infrared spectrum analysis module; the infrared spectrum analysis module responds to the wake-up instruction, then controls the tunable infrared light source to emit a sequence of light beams (estimated sectors), then receives the return light signal, and sends the spectrum data to the control processing unit. After receiving the transmitted spectrum data, the control processing unit begins to receive and analyze the spectrum data (coordinated orientation information), then performs differential spectrum calculations, and queries the corresponding pipeline type data to obtain information from the corridor geographic information system. The corridor geographic information system returns the pipeline type data to the control processing unit, and the control processing unit performs logical coupling (acoustic positioning, infrared characteristics, GIS), and then performs the final leakage verification judgment and issues a judgment result (leakage / non-leakage). The process ends at the control processing unit and the corridor geographic information system. Figure 2 As shown in the figure, the whole process starts with a quantum cascade laser with a tuning range of 3 to 5 microns. It emits a pulse-coded beam with a pulse width of 100 nanoseconds. The beam irradiates the target gas area with an absorption rate of 30%. After absorption, the beam forms an attenuation signal, which eventually reaches the reflective structure. Figure 3 As shown, the process starts with receiving the acoustic signal, and then judges whether it meets the leakage characteristics. If the judgment result is no, the process loops back to receiving the acoustic signal for continuous monitoring; if the judgment result is yes, the sound source direction is calculated, and then the corresponding wavelength combination is activated, and then a directional infrared beam is emitted, and then the target area spectral data is collected, and then the background reference area data is obtained, and then the differential spectrum is calculated, and then the absorbance threshold judgment is performed; if the result of the absorbance threshold judgment is greater than the threshold, the pipeline type is retrieved, and then the gas and pipeline are matched. If the matching result is yes, the leakage event is confirmed. If the matching result is no, continuous monitoring is entered; if the result of the absorbance threshold judgment is less than the threshold, continuous monitoring is directly entered, and finally, the process ends at continuous monitoring.

[0058] Example 3: Performance Verification Test of a Trace Methane Leak Identification System Based on an Acoustic-Optical Synergistic Mechanism in the Presence of Multi-Source Interference. The experimental background and objectives are as follows: In a typical urban underground utility corridor environment, due to the high degree of enclosure, complex gas composition, and frequent interference factors, existing infrared spectroscopy detection systems commonly suffer from delayed response, frequent false alarms, and high power consumption in identifying trace methane leaks. This systematic test was designed to verify the effectiveness and feasibility of the directional infrared spectroscopy identification mechanism based on acoustic triggering in this invention under complex environmental conditions. The test objectives included: verifying the trigger sensitivity of the acoustic sensor array to typical leak acoustic signals and its spatial positioning accuracy; evaluating the ability of the differential spectroscopy mechanism to extract characteristic absorption peaks of the target gas in a complex interference environment; quantitatively analyzing the system's minimum detectable level (MDL) for trace methane leaks; and confirming through data analysis the engineering feasibility of the closed-loop judgment path of the triple mechanism of sound source orientation determination, infrared signature recognition, and GIS logic coupling described in the technical solution.

[0059] In the experiment, the test section was about 96 meters long and was divided into four functional sections, A to D. Each section simulated typical pipeline environments such as gas, water supply, electricity and communications. Section B was equipped with a gas simulation pipeline made of PE composite materials, filled with a methane and air mixture with a volume fraction of 0.8% to 1.5%, and a controllable discharge device was used to simulate instantaneous rupture leakage scenarios. In order to reproduce complex interference conditions, a high-humidity steam source, a temperature disturbance generator and a diesel engine exhaust simulator were introduced into the non-leakage area, section D, to simulate common interference sources such as water vapor, temperature rise and volatile organic compounds (VOCs). During the test, the ambient humidity was maintained at 75% to 88%, the background temperature fluctuated between 22°C and 34°C, and the background VOCs concentration was controlled between 50 and 120 ppm.

[0060] The system installation plan includes the following: an acoustic sensor array, installed at the center axis of the Section B tunnel ceiling at a height of 2.2 meters above the ground, consisting of four MEMS acoustic arrays with a 0.5-meter spacing and symmetrically arranged elements. An infrared transmitter module, located on one wall of Section B, incorporates a quantum cascade laser array covering the 3.2- to 4.4-micron wavelength range, with the primary emission wavelength targeted at the characteristic methane absorption peak of 3.31 microns. An infrared receiver module, located on the opposite wall with an optical path length of approximately 8.7 meters, is coated with a high-reflectivity material to enhance the optical signal. A control and processing unit, integrated into a mobile test platform, features differential spectral analysis and identification capabilities linked to a GIS database. The infrared laser pulse width is set to 100 nanoseconds and the emission frequency to 1 kHz. The absorbance threshold is preset to 0.15, and the lower confidence limit required for final leak event determination is set to 80%.

[0061] Before the formal test, the system completed three rounds of preliminary commissioning tests to optimize the infrared laser emission angle (ultimately set to ±10°) and the sound source time delay judgment threshold (set to 0.12 milliseconds). During the formal test, each test set followed the complete process of "acoustic pre-triggering - infrared directional detection - background contrast difference". The following is a typical data record of the fourth set (initial leakage concentration was 1.1%, and the discharge aperture was 1.5 mm):

[0062]

[0063] The above data was tested three times after each sampling session, and the absorbance deviation was consistently less than 0.02, demonstrating the system's excellent stability. After receiving the positioning data, the control processing unit matched the pipeline segments with the GIS database, confirming that Section B was a gas pipeline area. It then generated an alarm message and uploaded it to the remote platform via the LTE module. The overall system response delay was kept within 1.2 seconds.

[0064] The experimental results show that when the leakage volume fraction is 1.1%, the system can stably extract the characteristic absorption peak of methane at a wavelength of 3.31 microns through the differential spectroscopy mechanism. The measured average absorbance is 0.24, which is higher than the preset judgment threshold. After sound source positioning, infrared identification and GIS attribute matching, the average confidence level of the leakage event generated by the system reaches 96.4%, the false alarm rate is controlled within 2%, and the missed alarm rate is about 1.5%. Under simulated interference conditions, the system can reliably identify methane leaks with a minimum volume fraction of 0.6%, with a response time of no more than 1.5 seconds, showing higher response speed and adaptability than traditional continuous scanning infrared systems. At the same time, it was observed that when the discharge aperture is less than 0.7 mm, the main frequency of the acoustic signal deviates to below 40 kHz, resulting in trigger failure in some test groups. It is recommended to expand the frequency response range of the acoustic array in subsequent optimization designs to further improve the system's coverage of weak leaks.

[0065] Example 4: In a typical urban integrated pipeline corridor operation and maintenance scenario, in order to achieve rapid response and precise positioning of trace gas leakage incidents, the leakage gas identification system based on infrared spectroscopy analysis described in the present invention is deployed. The system mainly serves a dual-channel multi-type pipeline area that passes through residential areas and municipal hubs. The gas pipelines in the area are staggered with communications, electricity, and water supply and drainage systems. The environment is complex and changeable. Once a leakage incident occurs, it is very likely to cause major safety hazards. Therefore, this embodiment is centered around the "automatic identification of micro-gas leakage incidents in the early morning when the guard is weak" as the background, and specifically demonstrates the actual operation process and key technical details of the system of the present invention.

[0066] During periods of low nighttime surveillance, the system enters a low-power monitoring mode. Four acoustic sensor arrays, located at the intersection of the main ventilation ducts, continuously sample background acoustic data. These arrays cover a frequency range of 28,000 to 75,000 Hz, with a sampling rate of 350,000 Hz. They are primarily designed to capture discontinuous pulse wave signals generated by the transient escape of high-pressure gas through microcracks. Each array consists of four micro-electromechanical acoustic elements, evenly spaced at a 45-degree angle to achieve spatial vector positioning. Their output signals are fed into a local edge processor via a parallel analog-to-digital conversion module and fed into a pre-set abnormal waveform matching model for real-time analysis.

[0067] At approximately 3:21 AM, the second zone of the sensor array triggered three consecutive anomalous acoustic events that met the specified trigger conditions. The signal characteristics were a narrowband transient signal with an amplitude jump greater than five times the standard noise level within 0.32 milliseconds and a center frequency between 37,000 and 43,000 Hz. Based on the acoustic propagation time differences between the array zones, the local control processing unit determined the azimuth of the leak source to be 12 degrees east of north, with a spatial error of less than 0.4 meters. The system immediately used this azimuth information as a parameter to activate the infrared spectroscopy analysis module and, through synchronized clock pulses, drive the lasers in the quantum cascade laser array at the preset methane absorption wavelength.

[0068] After this trigger, the system completed the infrared beam adjustment within 0.5 seconds. According to the above-mentioned azimuth angle setting, the laser emission angle was adjusted to twelve degrees east of north in the horizontal plane and fifteen degrees in the vertical plane. The emission pulse waveform was set to a width of one hundred nanoseconds and a repetition frequency of one thousand hertz. The incident light beam was reflected by the high-reflectivity aluminum fluoride material installed on the inner wall of the corridor and focused on the estimated leakage sector. Infrared detectors are deployed on the opposite pipe wall and are encapsulated with dust-proof filters and temperature-stabilized packaging to enhance environmental adaptability. To generate comparable differential spectra, after completing target sector sampling, the system immediately directs the laser toward a background reference area untriggered by the acoustic array and collects reflected infrared signals at the same wavelength combination. The control processing unit calculates each absorption peak using the absorbance function based on the ratio of the light intensities at the same wavelength in the two regions within the current frame. The resulting differential value at the characteristic absorption wavelength of 3.31 microns is 0.24. The system's built-in absorbance judgment threshold is 0.15. Based on the distribution fitting of 120 sets of experimental data, this value is the optimal judgment threshold to ensure a false alarm rate of less than 3% and a false negative rate of less than 1%. Simultaneously, the system queries the local pipeline corridor geographic information database to confirm that the current spatial coordinates correspond to a gas main and that the pipe section is made of high-pressure polyethylene composite pipe, which poses a typical methane leak risk. Because the infrared absorption characteristics, acoustic positioning results, and GIS pipe section attributes all met the leakage conditions, the system confirmed that this incident was a real leak and generated a complete alarm data packet containing the type of leaked gas, estimated coordinates (such as 35.4 meters east longitude and 6.8 meters north latitude), absorbance value, and judgment confidence level (96.38 percent).

[0069] To further reduce the system's risk of misjudgment and enhance the relevance of subsequent response strategies, the control processing unit calculated a joint judgment score for this incident. This score consists of three sub-items: first, acoustic signal similarity, which was scored at 88 out of 100; second, infrared spectrum matching, which was scored at 93, based on spectrum symmetry, peak shift rate, and spectrum amplitude; and third, GIS pipeline attribute matching, which was scored at 95, a weighted combination of the leak area type, the physical properties of the gas contained, and past maintenance records. The weights for these three items were set at 3:4:3, resulting in a weighted average score of 91.6, well above the system's lower alarm limit of 80.0.

[0070] Subsequent tracking data from this operation indicates that gas maintenance personnel in the area arrived at the scene at 4:10 AM and confirmed the source of the leak to be a microcrack in the pipe wall. The leaked gas was methane, and the concentration matched the system's pre-alarm estimate. The error between the actual leak location and the system's positioning result was less than 0.6 meters. This result fully demonstrates the system's high response sensitivity and spatial recognition accuracy for trace gas leaks in low-interference nighttime scenarios. It also further demonstrates that the multimodal fusion judgment system, built on a triple verification mechanism of acoustic wakeup, infrared differential absorption, and GIS, can effectively reduce the risk of false alarms and missed alarms, achieving an intelligent pipeline corridor gas leak monitoring solution with high engineering practicality.

[0071] Example 5: In this embodiment, an acoustic sensor array continuously monitors the background acoustic environment. Upon detecting a characteristic pulse waveform, the system constructs a two-dimensional localization model based on the time delay between the received signals between the sensors. This model derives the spatial coordinates (x, y) of the leak source and transmits these coordinates to the control processing unit. To clarify the physical connection between sound source localization and infrared spectral response, this embodiment incorporates spatial domain constraints into the control logic. Specifically, the infrared detection module is activated only when the sound source localization result satisfies a coordinate error of less than 0.6 meters and the center frequency of the signal waveform falls within a preset recognition window (e.g., 35kHz to 45kHz).

[0072] After the infrared detection module is activated, the tunable quantum cascade laser array selects the emission direction based on the acoustic positioning results and constructs the beam sector. The returned infrared signal is collected in the target area and the control signal is collected synchronously in the background reference area. The control processing unit then calculates the differential absorbance according to the following formula:

[0073] ,

[0074] in, Indicated by wavelength The infrared light intensity returned by the background reference area, Indicates that at the same wavelength The infrared light intensity returned by the target area at the location of the target area is calculated automatically by the internal module of the control processing unit, and the calculation result is used to determine whether there is characteristic absorption attenuation. Specifically: and They are all average values ​​of infrared detector samples with an integration time of 1 millisecond, and the unit is the normalized light intensity ratio (a floating point number between 0 and 1), which is automatically normalized by the digital signal processing module. In order to eliminate systematic errors caused by ambient temperature fluctuations, short-term drift of the light source, etc., the system automatically performs baseline calibration before each measurement, and checks the laser state stability with a wavelength deviation of less than ±0.02μm as the standard to ensure that the absorbance calculation logic strictly corresponds to the actual gas absorption behavior. In addition, in this embodiment, the control processing unit also constructs the absorbance threshold decision logic. Set the warning threshold The value is 0.15, which is derived from a large number of offline background sample distribution analysis. It can effectively distinguish gas leakage from normal fluctuations when a certain confidence level is met. , it is considered that the characteristic absorption peak is detected; otherwise, the band is judged as non-leakage.

[0075] To enhance the system's ability to interpret spectral responses, this embodiment incorporates the first-order derivative of the absorbance curve as an auxiliary basis for judgment. If both a sudden increase in absorption amplitude and spectral line symmetry are present near the target wavelength (±0.05μm), this further confirms that the feature exhibits gas absorption behavior. This judgment is achieved through a curve-fitting algorithm embedded in the software module, eliminating the need for additional sensors. Combining the aforementioned acoustic positioning results with the absorbance judgment results, the system enters the logical coupling judgment stage. The control processing unit calls the local database to retrieve the pipeline type in the coordinate area where the sound source is located. If the gas type corresponding to the identified absorption peak wavelength matches the logic of the pipeline medium in the area, the leakage event is finally confirmed; if it is inconsistent, the event is marked as a suspicious signal and enters the manual review mechanism. In this embodiment, in order to avoid false triggering of the system in a strong interference environment, the selection mechanism of the background reference area is further clarified. The background area must meet the requirements confirmed by the acoustic array that there has been no high-energy acoustic emission event in the past 5 seconds, and the distance from the target area must not exceed 8 meters to ensure the consistency of its environmental background. This constraint ensures that the reference signal truly reflects the current environmental benchmark state and avoids misjudgment due to background fluctuations.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An underground pipe gallery gas leakage identification system based on infrared spectroscopy analysis, characterized in that: include: a) at least one acoustic sensor unit configured to passively monitor acoustic signals in the pipe gallery and, upon detecting a signal meeting a preset acoustic characteristic of a gas leak, generate a wake-up command and position information indicating a preliminary position of the sound source; b) an infrared spectrum analysis module, communicatively connected to the acoustic sensor unit, the infrared spectrum analysis module comprising: i. A tunable infrared light source, in response to the wake-up command and according to the position information, emits a sequence of infrared detection beams comprising at least two different wavelengths to the estimated leakage sector, wherein the at least two different wavelengths correspond to characteristic absorption peaks of at least two key target gases; ii. an infrared detector for receiving infrared light returned from the estimated leakage sector and generating spectral data of the target area comprising at least two different wavelengths of infrared light intensity; c) a control processing unit connected to the acoustic sensor unit and the infrared spectrum analysis module, configured to: i based on the position information, controlling the emission direction of the tunable infrared light source and / or the wavelength combination contained in the infrared detection beam sequence; ii. Receiving and processing the target area spectral data, by analyzing the attenuation degree of infrared light intensity of at least two different wavelengths, identifying the infrared absorption characteristics of potential gas leaks; iii. When an infrared absorption characteristic of at least one potential leaking gas that meets a preset absorption intensity threshold is identified and the type of the potential leaking gas matches the preset pipeline type within the estimated leakage sector indicated by the position information, a leak event is confirmed and an alarm signal is output; The acoustic sensor unit includes an acoustic anisotropic microstructure sensor array, and the control processing unit is further configured to calculate two-dimensional coordinate information or three-dimensional coordinate information of the sound source based on time delays or intensity differences between acoustic signals received by different sensors in the array to optimize the orientation information and determine an estimated leakage sector; The infrared spectrum analysis module is further configured to, simultaneously with or after the tunable infrared light source emits the infrared detection beam sequence toward the estimated leakage sector, instruct it to emit the same infrared detection beam sequence toward at least one background reference area confirmed by the acoustic sensor unit and currently having no leakage acoustic signal, to obtain background spectrum data; and the control processing unit is further configured to calculate the intensity difference between the target area spectrum data and the background spectrum data at corresponding wavelengths to obtain a differential spectrum, and identify infrared absorption characteristics based on the differential spectrum; The control processing unit is further configured to access a database storing pipeline corridor geographic information system data, which contains pipeline type information in different areas of the pipeline corridor; the control processing unit determines the pipeline corridor area where the potential leakage source is located based on the orientation information, and retrieves the pipeline type contained in the area from the database, and logically matches the identified potential leakage gas type with the retrieved pipeline type. Only when the matching result is consistent, the leakage event is confirmed.

2. The underground pipe gallery gas leakage identification system based on infrared spectroscopy analysis as claimed in claim 1, characterized in that: The control processing unit calculates the characteristic absorption wavelength of the specific target gas in the differential spectrum Absorbance at ,in, , is the background spectrum at wavelength The light intensity at The target area spectrum at wavelength The light intensity at When the value is greater than the preset leakage judgment threshold, it is preliminarily determined that there is leakage of the target gas.

3. The underground pipe gallery gas leakage identification system based on infrared spectroscopy analysis as claimed in claim 1, characterized in that: The tunable infrared light source includes a quantum cascade laser array. Each laser in the array emits infrared light with a characteristic absorption wavelength of the target gas. The control processing unit selectively activates at least one laser in the array according to the azimuth information.

4. The underground pipe gallery gas leakage identification system based on infrared spectroscopy analysis as claimed in claim 1, characterized in that: The tunable infrared light source includes a broadband infrared light source and a MEMS Fabry-Perot interferometer. The control processing unit generates an infrared detection beam sequence containing at least two different wavelengths by controlling the transmission wavelength of the interferometer.

5. The underground pipe gallery gas leakage identification system based on infrared spectroscopy analysis as claimed in claim 1, characterized in that: The preset gas leakage acoustic characteristics include ultrasonic signals in a specific frequency range or acoustic emission signals with a specific time domain envelope. The acoustic sensor unit includes a piezoelectric ceramic sensor or a MEMS microphone array and is configured with an acoustic filter for filtering out ambient noise.

6. The underground pipeline gallery gas leakage identification system based on infrared spectroscopy analysis as claimed in claim 1, characterized in that: The control processing unit is also configured to generate alarm information including the type of leaked gas and the estimated leakage location after confirming the leakage event, and send the alarm information to the remote monitoring platform.

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