Leakage position detection method and device based on physical nuclear magnetic detection

Abstract

The invention discloses a leakage position detection device based on physical nuclear magnetic detection, and the device comprises a transmitting coil which is used for transmitting a radio frequency pulse to a detected object so as to generate a radio frequency magnetic field which excites atomic nucleus to generate magnetic resonance; the receiving coil is used for collecting a magnetic resonance signal generated by the atomic nucleus; the signal processing unit is electrically connected with the receiving coil and is used for amplifying, filtering and digitalizing the magnetic resonance signal; the control unit is electrically connected with the transmitting coil and the signal processing unit and is used for controlling parameters of the radio frequency pulse according to a preset pulse sequence and coordinating a sampling time sequence of the signal processing unit; and the display unit is in communication connection with the control unit and is used for outputting a leakage detection result. The physical nuclear magnetic detection technology is introduced, and specific magnetic resonance relaxation time characteristics of leakage substances are utilized, so that centimeter-level high-precision positioning is realized, and interference of environmental noise and temperature and humidity is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of physical detection and inspection technology, and in particular to a method and device for detecting leakage locations based on physical nuclear magnetic resonance detection. Background Technology

[0002] In modern infrastructure and industrial production sectors, such as building structures, water conservancy projects, and industrial pipelines, early detection and precise location of leakage problems are crucial for ensuring facility safety.

[0003] Currently, common leak detection methods mainly include manual inspection, pressure testing, acoustic detection, and infrared thermal imaging. However, these technologies have significant limitations in practical applications: manual inspection is inefficient and struggles to detect hidden leaks; pressure testing is complex to operate, easily causes secondary damage to the pipeline system, and lacks sensitivity to minute leaks; acoustic detection is highly susceptible to interference from urban or industrial environmental noise, making signal identification difficult; and infrared thermal imaging is highly dependent on the temperature difference between the leaking material and the surrounding environment, and its accuracy drops significantly when the temperature difference is not significant or when the ambient temperature and humidity fluctuate widely. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for detecting leakage location based on physical nuclear magnetic resonance detection, so as to solve the problem of low accuracy of existing leakage detection methods.

[0005] To address the above problems, this invention discloses a leakage location detection device based on physical nuclear magnetic resonance (NMR) detection, comprising: A transmitting coil is used to transmit radio frequency pulses to the object being detected in order to generate a radio frequency magnetic field that excites atomic nuclei to resonate. A receiving coil is used to acquire the magnetic resonance signal generated by the atomic nuclei; A signal processing unit, electrically connected to the receiving coil, is used to amplify, filter, and digitize the magnetic resonance signal. The control unit is electrically connected to the transmitting coil and the signal processing unit respectively, and is used to control the parameters of the radio frequency pulse according to the preset pulse sequence and coordinate the sampling timing of the signal processing unit; The display unit is communicatively connected to the control unit and is used to output the leakage detection results.

[0006] Preferably, the receiving coil is an array structure composed of multiple receiving coils, and the control unit determines the coordinates of the leakage location by performing spatial correlation analysis on the signal strength received by each sub-coil in the array structure.

[0007] Preferably, the signal processing unit includes a feature extraction module for calculating the longitudinal relaxation time T1 and the transverse relaxation time T2 of the magnetic resonance signal.

[0008] Preferably, the transmitting coil and the receiving coil are connected to the signal processing unit via a coaxial cable, and the control unit and the display unit are connected via a wireless communication module.

[0009] This invention also discloses a method for detecting leakage locations based on physical nuclear magnetic resonance (NMR) detection, comprising the following steps: S1. The frequency, amplitude and pulse width of the radio frequency pulse are set by the control unit, and the transmitting coil is driven to apply a radio frequency magnetic field to the area to be detected. Before step S1, the static magnetic field strength is preset by the control unit according to the material of the object to be detected. The static magnetic field is generated by an external permanent magnet or electromagnet and is used to cause the atomic nuclei in the object to be detected to precess.

[0010] S2. The free induction decay signal generated by the energy released by the excited atomic nuclei is collected by the receiving coil and transmitted to the signal processing unit. S3. The signal processing unit digitizes the free induction decay signal to extract signal strength features and relaxation time features; the signal processing unit performs time-frequency transformation on the digitized signal to extract frequency domain features, and combines the relaxation time features to perform multi-feature fusion analysis to improve the accuracy of identifying the type of leakage material.

[0011] S4. By comparing the data analysis algorithm with a preset material parameter library, which stores the standard relaxation time range of different media under a specific magnetic field strength, the leakage material is distinguished as water or oil by matching the relaxation time features extracted in real time with the standard relaxation time range.

[0012] The type of leaking material is identified based on the relaxation time characteristics, and the leak location is determined by inversion based on the spatial distribution of signal intensity characteristics. In the step of inversion to determine the leak location, the center projection coordinates of the leak area are located by calculating the amplitude gradient of the signal in each channel of the receiving coil array and combining it with the electromagnetic field attenuation model.

[0013] The display unit can display at least one of the following in real time: signal strength distribution map, relaxation time distribution map, and three-dimensional coordinates of leakage location, and supports historical data comparison and trend analysis.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves centimeter-level high-precision positioning by introducing physical nuclear magnetic resonance detection technology and utilizing the unique magnetic resonance relaxation time characteristics of the leaking material, effectively avoiding interference from environmental noise and temperature and humidity. Secondly, the device adopts a non-contact design, eliminating the need to pressurize or disassemble the object being tested, ensuring the non-destructive nature of the detection process. Thirdly, through the precise modulation of radio frequency pulses by the control unit and the digital analysis by the signal processing unit, different media such as water and oil can be quickly identified, significantly improving the accuracy and detection efficiency of leak identification under complex working conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the device structure of the present invention.

[0016] Reference numerals in the attached diagram: 1. Transmitting coil; 2. Receiving coil; 3. Control unit; 4. Signal processing unit; 5. Display unit. Detailed Implementation

[0017] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0018] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figure 1 As shown, the leakage location detection device based on physical nuclear magnetic resonance detection in this embodiment includes: Transmitting coil 1 is used to transmit radio frequency pulses to the object being detected in order to generate a radio frequency magnetic field that excites atomic nuclei to resonate. Receiver coil 2 is used to collect magnetic resonance signals generated by atomic nuclei; The signal processing unit 4 is electrically connected to the receiving coil 2 and is used to amplify, filter and digitize the magnetic resonance signal; The control unit 3 is electrically connected to the transmitting coil and the signal processing unit respectively, and is used to control the parameters of the radio frequency pulse according to the preset pulse sequence and coordinate the sampling timing of the signal processing unit 4. Display unit 5 is connected in communication with control unit 3 and is used to output leakage detection results.

[0022] The receiving coil 2 is an array structure composed of multiple receiving coils 2. The control unit 3 determines the coordinates of the leakage location by performing spatial correlation analysis on the signal strength received by each sub-coil in the array structure.

[0023] The signal processing unit 4 includes a feature extraction module for calculating the longitudinal relaxation time T1 and the transverse relaxation time T2 of the magnetic resonance signal.

[0024] The transmitting coil 1 and the receiving coil 2 are connected to the signal processing unit 4 via a coaxial cable (a wireless connection can also be used; to ensure the effectiveness of transmission, a cable connection is less likely to result in data loss). The control unit 3 and the display unit 5 are connected via a wireless communication module (a communication cable can also be used; since data loss is unlikely here, or data loss does not affect use, a wireless communication module can be used here to ensure remote use).

[0025] This embodiment utilizes the magnetic resonance properties of atomic nuclei to detect leak locations. Atomic nuclei possess spin angular momentum and a magnetic moment. Under the influence of an external static magnetic field, the nucleus precesses, with its precession frequency proportional to the strength of the external static magnetic field. When a radio frequency pulse with the same precession frequency is applied to the object being detected, the atomic nucleus absorbs the energy of the radio frequency pulse, transitioning from a low energy level to a high energy level, generating a magnetic resonance phenomenon. When the radio frequency pulse stops, the atomic nucleus gradually releases the absorbed energy, returning to the low energy level. During this process, a magnetic resonance signal that decays over time is generated, called the free induction decay (FID) signal. In areas with leakage, the atomic nuclei of the leaking material (such as water or oil) will generate specific magnetic resonance signals. By analyzing the characteristics of these magnetic resonance signals, such as signal intensity, frequency, phase, and relaxation time, the properties, content, and location of the leaking material can be obtained. For example, different types of leaking materials have different magnetic resonance relaxation times. The longitudinal relaxation time (T1) and transverse relaxation time (T2) of water differ significantly from other materials. By measuring the T1 and T2 values, it can be determined whether the leaking material is water. Furthermore, based on the distribution of signal intensity, the extent and location of the leakage area can be determined. In the specific detection process, a transmitting coil 1 and a receiving coil 2 are first arranged around the object being detected. The transmitting coil 1 is used to emit radio frequency pulses to excite the atomic nuclei in the object being detected to produce a magnetic resonance phenomenon; the receiving coil 2 is used to receive the magnetic resonance signal generated when the atomic nuclei release energy. The received signal is transmitted to the signal processing unit 4, where it is amplified, filtered, digitized, and then analyzed and inverted using data analysis algorithms to determine the location of the leak.

[0026] The leakage location detection method based on physical nuclear magnetic resonance detection in this embodiment includes the following steps: S1. The frequency, amplitude and pulse width of the radio frequency pulse are set by the control unit 3, and the transmitting coil 1 is driven to apply a radio frequency magnetic field to the area to be detected; S2. The receiving coil 2 is used to collect the free induction decay signal generated by the energy released by the excited atomic nuclei, and the signal is transmitted to the signal processing unit 4. S3. The signal processing unit 4 performs digital processing on the free induction attenuation signal to extract signal strength features and relaxation time features. S4. By comparing the data analysis algorithm with the preset material parameter library, the leakage material type is identified based on the relaxation time characteristics, and the leakage location is determined by inverting the spatial distribution of the signal intensity characteristics.

[0027] In the step of inversion to determine the location of leakage, the center projection coordinates of the leakage area are located by calculating the amplitude gradient of the signals in each channel of the receiving coil array and combining the electromagnetic field attenuation model.

[0028] The material parameter library stores the standard relaxation time ranges of different media under specific magnetic field strengths. By matching the real-time extracted relaxation time characteristics with the standard relaxation time ranges, the leakage material can be distinguished as water or oil.

[0029] Also includes: Before step S1, the static magnetic field strength is preset by the control unit 3 according to the material of the object being tested. The static magnetic field is generated by an external permanent magnet or electromagnet and is used to cause the atomic nuclei in the object being tested to precess.

[0030] Step S3 also includes: The signal processing unit 4 performs time-frequency transformation on the digitized signal, extracts frequency domain features, and combines relaxation time features to perform multi-feature fusion analysis to improve the accuracy of identifying the type of leakage material.

[0031] The method also includes: The display unit 5 displays at least one of the following in real time: signal strength distribution map, relaxation time distribution map, and three-dimensional coordinates of leakage location, and supports historical data comparison and trend analysis.

[0032] Example 1 like Figure 1 As shown, the leakage location detection device in this embodiment mainly consists of a transmitting coil 1, a receiving coil 2, a control unit 3, a signal processing unit 4, and a display unit 5.

[0033] The transmitting coil 1 is a circular or square structure made of multiple turns of wire, and its inductance and capacitance are matched to achieve a preset resonant frequency. The transmitting coil 1 is arranged on the surface or periphery of the object being detected, and its main function is to generate a high-intensity radio frequency magnetic field under the drive of the control unit 3, so as to deflect the magnetic moments of atomic nuclei in the detected area.

[0034] Receiving coil 2 is used to capture the weak electromagnetic signals released by atomic nuclei during relaxation. Receiving coil 2 employs a coil array composed of multiple symmetrically distributed surface coils. This array design utilizes the signal intensity gradient generated by the distance differences between different coils and the leakage area, thereby improving the accuracy of spatial positioning through an amplitude comparison algorithm.

[0035] The control unit 3 includes a microprocessor and a pulse generator, which is responsible for precisely controlling the frequency (which must satisfy the Larmor frequency equation), amplitude, pulse width (such as a 90° pulse or a 180° pulse), and transmit repetition time (TR) of the radio frequency pulses. At the same time, the control unit 3 coordinates the turn-on time of the receiving coil 2 through a synchronization signal to avoid interference from high-power transmit pulses and protect subsequent circuits.

[0036] The signal processing unit 4 includes a low-noise amplifier (LNA), a bandpass filter, and an analog-to-digital converter (ADC). The microvolt-level analog signal induced by the receiving coil 2 is first amplified by the LNA, then filtered by the bandpass filter to remove ambient power frequency interference and spurious noise, and finally converted into a digital signal and transmitted to the main control chip for FFT (Fast Fourier Transform) and feature extraction.

[0037] The detection method provided in this embodiment includes the following steps: Step S101: System initialization. The control unit 3 sets the precession frequency of the target atomic nuclei and the static magnetic field strength compensation parameters according to the material of the object being detected (such as concrete, metal or plastic) and the expected leakage substance (such as water or oil).

[0038] Step S102: Signal Excitation. The transmitting coil 1 transmits a radio frequency pulse with a specific bandwidth according to a timing sequence. This pulse causes the hydrogen nuclei in the leakage region to absorb energy and undergo a transition from a low energy level to a high energy level.

[0039] Step S103: Signal Acquisition. After the dead time following the RF pulse stop, the receiving coil 2 array begins sampling. The sampled FID signal contains envelope information that decays over time.

[0040] Step S104: Data Processing and Feature Matching. The signal processing unit 4 calculates the longitudinal relaxation time T1 and the transverse relaxation time T2 of the acquired signal. Since the T1 and T2 values ​​of water differ significantly from those of ordinary soil or pore water in materials, the system determines the type of leakage material by comparing the real-time measured relaxation time with the built-in material parameter library.

[0041] Step S105: Location Inversion. The control unit 3 summarizes the signal strength of each sub-coil in the receiving coil array. According to the electromagnetic field attenuation model, the projection position corresponding to the center of the coil with the strongest signal is the center of the leakage area 7. The system uses a deconvolution algorithm combined with the phase information of the array signal to further accurately locate the three-dimensional coordinates of the leakage point.

[0042] Step S106: Result Output. Display unit 5 presents the leakage location, leakage degree, and material type in the form of a heat map or coordinate values, and triggers the early warning module.

[0043] In another implementation, the aforementioned device is integrated into a mobile robot platform. The robot carries a permanent magnet array to generate a localized static magnetic field, and detectors (transmitting and receiving coils) are mounted on a lifting mechanism at the bottom of the robot. The robot scans the outer wall of a large storage tank according to a preset trajectory, and generates a large-area leak distribution map by real-time correlation between integrated high-precision inertial navigation data and NMR signal strength. This method avoids the limitations of fixed installations and enables rapid, non-destructive testing of large-scale infrastructure.

[0044] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics of the solutions is not described in detail here. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A leakage location detection device based on physical nuclear magnetic resonance detection, characterized in that, include: The transmitting coil (1) is used to transmit radio frequency pulses to the object being detected in order to generate a radio frequency magnetic field that excites atomic nuclei to resonate. A receiving coil (2) is used to collect the magnetic resonance signal generated by the atomic nucleus; The signal processing unit (4) is electrically connected to the receiving coil (2) and is used to amplify, filter and digitize the magnetic resonance signal; The control unit (3) is electrically connected to the transmitting coil and the signal processing unit respectively, and is used to control the parameters of the radio frequency pulse according to the preset pulse sequence and coordinate the sampling timing of the signal processing unit (4); The display unit (5) is communicatively connected to the control unit (3) and is used to output the leakage detection results.

2. The leakage location detection device based on physical nuclear magnetic resonance detection according to claim 1, characterized in that, The receiving coil (2) is an array structure composed of multiple receiving coils (2). The control unit (3) determines the coordinates of the leakage location by performing spatial correlation analysis on the signal strength received by each sub-coil in the array structure.

3. The leakage location detection device based on physical nuclear magnetic resonance detection according to claim 1, characterized in that, The signal processing unit (4) includes a feature extraction module for calculating the longitudinal relaxation time T1 and the transverse relaxation time T2 of the magnetic resonance signal.

4. The leakage location detection device based on physical nuclear magnetic resonance detection according to claim 1, characterized in that, The transmitting coil (1) and the receiving coil (2) are connected to the signal processing unit (4) via a coaxial cable, and the control unit (3) and the display unit (5) are connected via a wireless communication module.

5. A method for detecting leakage location based on physical nuclear magnetic resonance (NMR) detection, characterized in that, Using the apparatus according to any one of claims 1-4, the steps include: S1. The frequency, amplitude and pulse width of the radio frequency pulse are set by the control unit (3), and the transmitting coil (1) is driven to apply a radio frequency magnetic field to the area to be detected. S2. The receiving coil (2) is used to collect the free induction decay signal generated by the energy released by the excited atomic nuclei, and the signal is transmitted to the signal processing unit (4). S3. The signal processing unit (4) performs digital processing on the free induction attenuation signal to extract signal strength features and relaxation time features. S4. By comparing the data analysis algorithm with the preset material parameter library, the leakage material type is identified based on the relaxation time characteristics, and the leakage location is determined by inverting the spatial distribution of the signal intensity characteristics.

6. The leakage location detection method based on physical nuclear magnetic resonance detection according to claim 5, characterized in that, In the step of determining the leakage location through inversion, the center projection coordinates of the leakage area are located by calculating the amplitude gradient of the signals in each channel of the receiving coil array and combining it with the electromagnetic field attenuation model.

7. The leakage location detection method based on physical nuclear magnetic resonance detection according to claim 5, characterized in that, The material parameter library stores standard relaxation time ranges for different media under specific magnetic field strengths. By matching the real-time extracted relaxation time features with the standard relaxation time ranges, the leakage material can be distinguished as water or oil.

8. The leakage location detection method based on physical nuclear magnetic resonance detection according to claim 5, characterized in that, Also includes: Before step S1, the static magnetic field strength is preset by the control unit (3) according to the material of the object being tested. The static magnetic field is generated by an external permanent magnet or an electromagnet and is used to cause the atomic nuclei in the object being tested to precess.

9. The leakage location detection method based on physical nuclear magnetic resonance detection according to claim 5, characterized in that, Step S3 also includes: The digitized signal is transformed by the signal processing unit (4) to extract frequency domain features, and then combined with the relaxation time features to perform multi-feature fusion analysis.

10. The leakage location detection method based on physical nuclear magnetic resonance detection according to claim 5, characterized in that, The method further includes: The display unit (5) displays at least one of the following in real time: signal strength distribution map, relaxation time distribution map, and three-dimensional coordinates of leakage location.

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