A temperature and acoustic characteristic synchronous detection method based on optical fiber sensing

Abstract

The present application relates to a kind of temperature and acoustic feature synchronous detection methods based on optical fiber sensing, belong to optical fiber sensing technical field, comprising: along the measured object layout sensing optical fiber, the detection region is divided into spatial detection section, to sensing optical fiber injection probe light, and in the same sampling cycle, the temperature response signal and acoustic response signal of each spatial detection section are obtained;According to temperature response signal, obtain temperature variation, according to acoustic response signal, obtain acoustic disturbance state, and according to thermal response time, temperature variation rate threshold and continuous sampling cycle number set temperature effective variation condition;Temperature variation meets condition when updating temperature output, not meet condition and exist acoustic disturbance state when maintaining last effective temperature output and temporarily suspending update, not meet condition but adjacent spatial detection section exists continuous temperature variation when retaining temperature variation for subsequent output, and output temperature detection result and acoustic disturbance mark.The method can reduce the risk of false update.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing technology, specifically a method for simultaneous detection of temperature and acoustic characteristics based on fiber optic sensing. Background Technology

[0002] In existing technologies, distributed fiber optic sensing technology typically utilizes the characteristic of continuous deployment of sensing fibers along the object being measured to perform long-distance, distributed detection of parameters such as temperature, vibration, and sound waves. Recent Chinese patent documents have begun to focus on multi-parameter fusion detection. For example, publication number CN112697180A discloses a fusion-type distributed fiber optic sensing system and method for simultaneous temperature and vibration measurement. This system achieves simultaneous demodulation of temperature and vibration signals by splitting scattered light and local oscillator light into two parts and performing heterodyne detection separately. Another example is publication number CN220960115U, which discloses a distributed fiber optic temperature and sound wave sensing system. This system achieves sound wave sensing through coherent detection and temperature sensing through Stokes scattering and anti-Stokes scattering correlation detection, thus integrating temperature and sound wave sensing functions into a single system. These solutions demonstrate that simultaneous acquisition of multiple physical quantities has become an important direction for fiber optic sensing engineering applications, providing richer status information than single temperature or single acoustic detection in scenarios such as pipe racks, cables, oil and gas pipelines, and structural health monitoring.

[0003] However, existing publicly available solutions primarily focus on improvements to optical path structure, detection channel configuration, scattered signal demodulation, and data acquisition hardware. The emphasis is on enabling the same sensing fiber or detection system to obtain both temperature and acoustic / vibration responses. However, they lack specific constraints on temperature output processing when temperature response signals and acoustic disturbance signals couple at the same spatial location and within the same sampling period. In actual detection processes, acoustic disturbances such as knocking, friction, impact, fluid pulsation, and mechanical vibration can cause transient changes in the local fiber's stress state, phase state, or scattered signal amplitude. These changes may manifest as short-term temperature jumps, localized abnormal rises and falls, or migratory fluctuations between spatial segments within the temperature channel. If the system only updates its output based on the instantaneous changes in the temperature response signal, it may easily misjudge non-thermal response changes caused by acoustic disturbances as actual temperature changes. Conversely, simply using filtering, averaging, or delayed output methods may suppress the initial changes of actual thermal events, affecting the timeliness and continuity of temperature alarms.

[0004] Therefore, in scenarios involving simultaneous detection of temperature and acoustic features, a method is needed that combines the thermal response time of the measured object, the temperature change rate threshold, the number of consecutive sampling periods, and the relationship between changes in adjacent spatial detection segments. This method enables the system to update its output promptly when temperature changes demonstrate thermal response continuity, maintain the previous valid temperature output when acoustic disturbances exist and temperature changes do not meet the valid change conditions, and retain the corresponding temperature changes for subsequent outputs when adjacent spatial detection segments exhibit continuous temperature changes. This approach improves the reliability of the correspondence between temperature detection results and acoustic disturbance markers without weakening the synchronous detection capability, reducing the risk of false updates, false alarms, and missed alarms caused by acoustic disturbances. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synchronous detection of temperature and acoustic characteristics based on fiber optic sensing, thereby addressing some of the drawbacks and shortcomings pointed out in the background art.

[0006] The present invention adopts the following technical solution to solve the above-mentioned technical problems:

[0007] A sensing fiber is laid out along the object under test, and the detection area corresponding to the sensing fiber is divided into multiple spatial detection segments. Detection light is injected into the sensing fiber, and the temperature response signal and acoustic response signal of each spatial detection segment are acquired within the same sampling period.

[0008] The temperature change is obtained based on the temperature response signal, the acoustic disturbance state is obtained based on the acoustic response signal, and the effective temperature change conditions of each spatial detection segment are set according to the thermal response time, temperature change rate threshold and number of continuous sampling cycles of the object under test.

[0009] When the temperature change satisfies the effective temperature change condition, the temperature output of the corresponding spatial detection segment is updated; when the temperature change does not satisfy the effective temperature change condition and the acoustic disturbance state exists, the previous effective temperature output is maintained and the update is temporarily suspended; when the temperature change does not satisfy the effective temperature change condition and there are continuous temperature changes in adjacent spatial detection segments, the temperature change is retained for subsequent temperature output, and the temperature detection results of each spatial detection segment and the corresponding acoustic disturbance flag are output.

[0010] Furthermore, when the temperature change in a certain spatial detection segment does not meet the effective temperature change condition and the acoustic disturbance state exists, the temperature response signal of the current sampling period is temporarily stored as a temperature signal to be released; after the acoustic disturbance state disappears, if the recovered temperature response signal is consistent with the temperature change direction of the temperature signal to be released, the temperature signal to be released is added to the temperature output process; otherwise, the temperature signal to be released is removed from the temperature output process.

[0011] Furthermore, when invoking the temperature response change state of adjacent spatial detection segments, adjacent spatial detection segments that are not in the acoustic disturbance state and whose temperature change direction is consistent are selected as temperature reference segments; when the current spatial detection segment is in the acoustic disturbance state, the temperature output of the current spatial detection segment is maintained, compensated, or delayed based on the temperature change direction and temperature change amplitude of the temperature reference segment, so as to maintain the continuity of the temperature output of the current spatial detection segment.

[0012] Furthermore, when multiple adjacent spatial detection segments sequentially exhibit the acoustic disturbance state within different sampling periods, the order in which the acoustic disturbance state occurs is recorded; if the temperature change exceeding the effective temperature change condition shifts between adjacent spatial detection segments according to the order of occurrence, the temperature change is removed from the temperature output process; if the temperature change remains in the same spatial detection segment after the acoustic disturbance state disappears, the temperature change is used for temperature output.

[0013] Furthermore, the temperature signal to be released is marked with a sampling time mark and a disturbance duration mark; after the acoustic disturbance state disappears, when the recovered temperature response signal is consistent with the temperature change direction of the temperature signal to be released within a preset number of consecutive sampling periods, the temperature signal to be released is added to the temperature output process.

[0014] Furthermore, when the same spatial detection segment generates multiple temperature signals to be released within adjacent sampling periods, a release sequence is generated according to the sampling order. After the acoustic disturbance disappears, the temperature signals to be released in the release sequence are compared with the recovered temperature response signal in turn according to their direction of change. Temperature signals to be released with the same direction of change are added to the temperature output process according to the sampling order, and temperature signals to be released with different directions of change are removed from the release sequence.

[0015] Furthermore, during the temporary storage of the temperature signal to be released, the previous valid temperature output corresponding to the spatial detection segment is maintained, and the participation priority of the corresponding spatial detection segment in the temperature continuity judgment of adjacent spatial detection segments is reduced; after the temperature signal to be released is added to the temperature output process, the participation priority of the corresponding spatial detection segment in the temperature continuity judgment is restored.

[0016] Furthermore, when the temperature change shifts between adjacent spatial detection segments according to the order of occurrence, the migration temperature change corresponding to the spatial detection segment is recorded. After the acoustic disturbance disappears, the migration temperature change is compared with the temperature change of the spatial detection segment where the acoustic disturbance initially occurred. If the migration temperature change does not persist in the spatial detection segment where the acoustic disturbance initially occurred, the migration temperature change is removed from the temperature output process.

[0017] Furthermore, if the temperature change remains within the same spatial detection segment after the acoustic disturbance disappears, the temperature change of the same spatial detection segment and its adjacent spatial detection segments will continue to be collected; if the temperature change of adjacent spatial detection segments continuously transitions to the same spatial detection segment, the update priority of the temperature output of the same spatial detection segment will be increased.

[0018] Furthermore, when the update priority of the temperature output of the same spatial detection segment is increased, the same spatial detection segment is restricted from participating in the process of determining the migration of temperature change based on the order of occurrence of the acoustic disturbance state and eliminating invalid temperature change within a preset recovery period; if the temperature change of the same spatial detection segment remains in the same spatial detection segment within the preset recovery period, the update priority is maintained; otherwise, the original temperature output priority is restored.

[0019] This invention deploys sensing optical fibers along the object under test and divides the detection area corresponding to the sensing optical fibers into multiple spatial detection segments. Within the same sampling period, it acquires the temperature response signal and acoustic response signal of each spatial detection segment, so that the temperature detection result and the acoustic disturbance state have a common source, synchronization and segmented correspondence. This is beneficial for subsequent judgment on whether the temperature change belongs to the real thermal response, and avoids misjudgment caused by updating the output based on only a single temperature response signal.

[0020] This invention sets effective temperature change conditions based on the thermal response time of the object being measured, the temperature change rate threshold, and the number of consecutive sampling periods. When the temperature change meets these conditions, the temperature output is updated. When the temperature change does not meet these conditions and there is an acoustic disturbance, the previous effective temperature output is maintained and the update is temporarily suspended. This can suppress the interference of acoustic disturbances, mechanical shocks, or transient vibrations on the temperature output and improve the stability and reliability of the temperature detection results.

[0021] When the temperature change does not meet the effective temperature change condition but there is a continuous temperature change in the adjacent spatial detection segment, the present invention does not directly discard the temperature change, but retains it for subsequent temperature output, and simultaneously outputs an acoustic disturbance flag, so that the system can take into account both anomaly suppression and real thermal change tracking, reduce the probability of false alarms and missed alarms, and improve the engineering applicability of distributed optical fiber temperature and acoustic feature synchronous detection. Attached Figure Description

[0022] Figure 1 This is a flowchart of the synchronous detection process of temperature and acoustic features in this invention.

[0023] Figure 2 This is a threshold determination diagram for the rate of temperature change in Embodiment 1 of the present invention.

[0024] Figure 3 This is a diagram confirming the consistency of the direction of the temperature signal to be released in Embodiment 1 of the present invention.

[0025] Figure 4 This is a timing diagram of temporary storage replenishment and participation priority recovery in Embodiment 1 of the present invention.

[0026] Figure 5 This is a diagram showing the spatial transfer rate determination of acoustic disturbances in Embodiment 2 of the present invention.

[0027] Figure 6 This is a diagram showing the removal of temperature changes due to disturbance migration in Embodiment 2 of the present invention.

[0028] Figure 7 This is a diagram showing the continuous temperature change and update priority adjustment in Embodiment 2 of the present invention. Detailed Implementation

[0029] As attached Figure 1As shown, in one embodiment, a sensing fiber is first laid out along the extension direction of the object under test or the area to be detected, so that the sensing fiber and the object under test form a stable thermal coupling and acoustic coupling relationship. A stable thermal coupling relationship means that the sensing fiber can generate a recognizable temperature response to temperature changes at the corresponding detection position of the object under test. A stable acoustic coupling relationship means that acoustic disturbances in the object under test or the area to be detected can be transmitted to the sensing fiber and cause a recognizable acoustic response. After the fiber is laid out, the detection area corresponding to the sensing fiber is divided into multiple spatial detection segments according to spatial location, with each spatial detection segment corresponding to a detection position on the object under test. During detection, probe light is injected into the sensing fiber, and the optical signals returned from each spatial detection segment are collected within the same sampling period. The temperature response signal and the acoustic response signal are then obtained based on the returned optical signals. The temperature response signal characterizes the temperature change of the corresponding spatial detection segment, and the acoustic response signal characterizes the vibration, impact, or sound pressure disturbance of the corresponding spatial detection segment, thus enabling the same spatial detection segment to simultaneously possess temperature detection information and acoustic disturbance information within the same sampling period. Subsequently, the temperature change of the corresponding spatial detection segment is calculated based on the temperature response signal, and the presence of acoustic disturbance in the corresponding spatial detection segment is identified based on the acoustic response signal. In combination with the thermal response time of the object under test, the temperature change rate threshold, and the number of continuous sampling cycles, effective temperature change conditions are set for each spatial detection segment.

[0030] The effective temperature change condition includes the correspondence between the temperature change amount and the temperature change rate threshold, the duration of the temperature change within a continuous sampling period, and the matching between the temperature change and the thermal response time of the measured object. This effective temperature change condition distinguishes between temperature changes caused by actual thermal changes and those potentially affected by acoustic disturbances. When the temperature change amount meets the effective temperature change condition, it indicates that the temperature change in the corresponding spatial detection segment conforms to the thermal inertia characteristics of the measured object, and the temperature output of that spatial detection segment is updated. When the temperature change amount does not meet the effective temperature change condition, and there is acoustic disturbance in the corresponding spatial detection segment, it is considered that the temperature change amount may be affected by acoustic disturbances, and the previous effective temperature output is maintained and updates are temporarily suspended. When the temperature change amount does not meet the effective temperature change condition, but there is continuous temperature change in adjacent spatial detection segments, it indicates that the temperature change amount may be related to thermal conduction or thermal diffusion processes in space, and the temperature change amount is retained for subsequent temperature output judgment. Continuous temperature change refers to adjacent spatial detection segments having the same or similar temperature change direction within adjacent sampling periods or continuous sampling periods, and the temperature change exhibiting a continuous transition state in spatial location. Through the above processing, when outputting the temperature detection results of each spatial detection segment, the corresponding acoustic disturbance marker can be given at the same time, thereby improving the stability and reliability of the temperature detection results under acoustic disturbance environment.

[0031] Based on the above implementation, when the temperature change of a certain spatial detection segment does not meet the effective temperature change condition, and the acoustic response signal indicates that the spatial detection segment is in an acoustic disturbance state, the system does not directly use the temperature response signal of that sampling period to update the temperature output. Instead, it temporarily stores the temperature response signal as a temperature signal to be released. The temperature signal to be released is used to store temperature change information that may be disturbed during the acoustic disturbance, so as to avoid abnormal temperature output jumps caused by acoustic disturbances. When temporarily storing the temperature signal to be released, the system adds a sampling time marker and a disturbance duration marker to the signal, so that subsequent judgments can be made by combining the signal generation time and the duration of acoustic disturbances. The disappearance of the acoustic disturbance state means that the acoustic response signal of the corresponding spatial detection segment is lower than the disturbance judgment level within a preset sampling period, or no longer exhibits the abrupt change characteristics corresponding to the acoustic disturbance. After the acoustic disturbance state disappears, the system continues to collect the temperature response signal of the corresponding spatial detection segment and compares the recovered temperature response signal with the temperature signal to be released in terms of temperature change direction. The direction of temperature change includes the direction of heating up, the direction of cooling down, and the direction of holding. The system uses the previous effective temperature output of the detection segment in this space as a reference to determine the direction of temperature change of the temperature signal to be released and the temperature response signal after recovery.

[0032] When the recovered temperature response signal matches the temperature change direction of the temperature signal to be released within a preset number of consecutive sampling periods, it indicates that the temporary temperature change during the acoustic disturbance matches the actual temperature change trend after the disturbance disappears. In this case, the temperature signal to be released is added to the temperature output process. When the recovered temperature response signal does not match the temperature change direction of the temperature signal to be released, it indicates that the temperature signal to be released may be caused by acoustic disturbance, and the system removes the temperature signal to be released from the temperature output process. When multiple temperature signals to be released are generated in adjacent sampling periods in the same spatial detection segment, the system generates a release sequence according to the sampling order. After the acoustic disturbance disappears, the system compares the change direction of each temperature signal to be released in the release sequence with the recovered temperature response signal in turn. For temperature signals to be released with the same change direction, the system adds them to the temperature output process according to the sampling order; for temperature signals to be released with different change directions, the system removes them from the release sequence. During the temporary storage of the temperature signal to be released, the system maintains the previous valid temperature output of the corresponding spatial detection segment and reduces the participation priority of the spatial detection segment in the temperature continuity judgment of adjacent spatial detection segments, so as to reduce the impact of the disturbed spatial detection segment on the surrounding temperature continuity judgment.

[0033] The participation priority indicates the degree to which the temperature change of a spatial detection segment is used in the temperature continuity judgment. When the participation priority is reduced, the system prioritizes the use of adjacent spatial detection segments that are not in an acoustic disturbance state as the judgment basis. After the temperature signal to be released is added to the temperature output process, the system restores the participation priority of the corresponding spatial detection segment in the temperature continuity judgment, thereby taking into account both the stability of the temperature output during the disturbance and the integrity of the temperature change after the disturbance disappears.

[0034] Based on the above implementation method, when determining whether the temperature output of the current spatial detection segment needs adjustment, the system can use the temperature response change status of adjacent spatial detection segments as a reference. Specifically, the system first obtains the acoustic disturbance state and temperature change of spatial detection segments on both sides or adjacent to the current spatial detection segment, and selects the spatial detection segment that is not in an acoustic disturbance state and whose temperature change direction is consistent with that of the current spatial detection segment as the temperature reference segment. When the temperature change direction of the current spatial detection segment cannot be determined under acoustic disturbance, the system uses the temperature change direction of the current spatial detection segment before the disturbance as the reference direction, and selects the adjacent spatial detection segment consistent with the reference direction as the temperature reference segment.

[0035] Since the temperature reference segment is unaffected by acoustic disturbances, its temperature response changes can reflect the true thermal change trend of the measured object in adjacent areas. When there is an acoustic disturbance in the current spatial detection segment, the system does not directly update the temperature output based on the temperature response signal of the current spatial detection segment. Instead, it processes the temperature output of the current spatial detection segment by combining the temperature change direction and amplitude of the temperature reference segment. If the temperature change direction of the temperature reference segment is consistent with the temperature change direction of the current spatial detection segment before the disturbance, the system can maintain the previous valid temperature output of the current spatial detection segment; if the temperature change amplitude of the temperature reference segment indicates a continuous thermal change trend in adjacent areas, the system can compensate for the temperature output of the current spatial detection segment.

[0036] Compensation refers to the smooth adjustment of the temperature output of the current spatial detection segment, based on the direction and magnitude of temperature changes in a temperature reference segment, while maintaining the continuity of temperature output. This ensures that the temperature output matches the continuous thermal change trend of adjacent areas. If the trend of the temperature reference segment is not yet stable, the system can delay the update of the temperature output of the current spatial detection segment. An unstable trend means that the direction of temperature change in the temperature reference segment changes repeatedly within the continuous sampling period, or that the magnitude of temperature change does not exhibit a continuous change state that can be used for reference. Through this method, when the current spatial detection segment is affected by acoustic disturbances, the temperature output continuity of the current spatial detection segment can be maintained by utilizing the temperature response changes of adjacent spatial detection segments, reducing the impact of single-point disturbances on the overall temperature detection results.

[0037] Based on the above implementation method, when multiple adjacent spatial detection segments sequentially experience acoustic disturbances within different sampling periods, the system records the order in which these disturbances occur and uses this order as the basis for determining the source of the temperature change. Specifically, if a temperature change exceeds the effective temperature change condition, and the location of this temperature change shifts between adjacent spatial detection segments following the sequence of acoustic disturbance occurrences, it indicates that the temperature change may be caused by the propagation of acoustic disturbances along spatial positions, rather than by a real temperature change generated by the measured object at a fixed position. In this case, the system removes this temperature change from the temperature output process to avoid erroneous updates to the temperature detection results due to acoustic disturbances. If the temperature change remains within the same spatial detection segment after the acoustic disturbance disappears, it indicates that the temperature change has a high correlation with the actual thermal change at the corresponding spatial position, and the system uses this temperature change for temperature output.

[0038] As the temperature change shifts between adjacent spatial detection segments in the sequence of acoustic disturbance occurrences, the system records the migration temperature change for the corresponding spatial detection segment. After the acoustic disturbance disappears, the system compares the migration temperature change with the temperature change in the spatial detection segment where the acoustic disturbance initially occurred. The migration temperature change refers to the temperature change that shifts position between adjacent spatial detection segments in the sequence of acoustic disturbance occurrences. If the migration temperature change does not persist in the spatial detection segment where the acoustic disturbance initially occurred, the system determines that the migration temperature change does not have a stable spatial correspondence and removes it from the temperature output process. If the temperature change remains in the same spatial detection segment after the acoustic disturbance disappears, the system continues to collect the temperature changes of that spatial detection segment and its adjacent spatial detection segments, and determines whether the temperature change of the adjacent spatial detection segments forms a continuous transition to that spatial detection segment.

[0039] When the temperature change of an adjacent spatial detection segment continuously transitions to that spatial detection segment, it indicates that the temperature change in that segment may be part of a local thermal change process of the measured object. In this case, the update priority of the temperature output of that spatial detection segment is increased. The update priority indicates the order and degree of adoption of the temperature change of that spatial detection segment in the temperature output update judgment. When the update priority is increased, the system prioritizes judging whether the temperature change of that spatial detection segment meets the characteristics of a true local temperature change. After increasing the update priority, the system restricts that spatial detection segment from participating in the processing of invalid temperature changes that occur during acoustic disturbance state transitions within a preset recovery period, in order to avoid true temperature changes being misjudged as disturbance migration.

[0040] If the temperature change in the spatial detection segment remains within the same spatial detection segment within the preset recovery period, the update priority is maintained; if the temperature change fails to remain within the same spatial detection segment, the original temperature output priority is restored, thereby improving the ability to identify real local temperature changes while suppressing the influence of acoustic disturbances.

[0041] Example 1:

[0042] This embodiment provides a method for simultaneous detection of temperature and acoustic characteristics based on fiber optic sensing. It can be used for temperature detection and acoustic disturbance identification of tubular, plate-shaped, or linearly extending objects under test in a given unit. In implementation, a sensing fiber is laid along the extension direction of the object under test, establishing a stable thermal and acoustic coupling relationship between the sensing fiber and the object. The detection area corresponding to the sensing fiber is divided into multiple spatial detection segments, each corresponding to a detection position on the object under test.

[0043] During detection, probe light is injected into the sensing fiber, and temperature response signals and acoustic response signals of each spatial detection segment are acquired within the same sampling period. The temperature response signal is used to obtain the temperature value and temperature change of the corresponding spatial detection segment, while the acoustic response signal is used to determine whether there is acoustic disturbance caused by vibration, impact, or sound pressure disturbance in the corresponding spatial detection segment. Thus, the same spatial detection segment simultaneously possesses temperature detection information and acoustic disturbance information within the same sampling period.

[0044] In this embodiment, the system sets effective temperature change conditions based on the thermal response time of the object under test, the temperature change rate threshold, and the number of consecutive sampling periods. These effective temperature change conditions are used to determine whether the temperature change in the current sampling period matches the true thermal change characteristics of the object under test. When the temperature change meets the effective temperature change conditions, the system updates the temperature output of the corresponding spatial detection segment; when the temperature change does not meet the effective temperature change conditions and acoustic disturbances exist, the system retains the previous effective temperature output and postpones updating; when the temperature change does not meet the effective temperature change conditions but there are continuous temperature changes in adjacent spatial detection segments, the system retains the temperature change for subsequent temperature output judgment.

[0045] To obtain the temperature change in the current sampling period, the system subtracts the temperature response values ​​of the same spatial detection segment from those of two adjacent sampling periods. This process can be expressed by the following formula:

[0046]

[0047] in, Indicates the first The spatial detection segment in the first The temperature change in each sampling period relative to the previous sampling period, in °C; Indicates the first The spatial detection segment in the first The temperature value obtained from the temperature response signal in each sampling period is in °C; Indicates the same spatial detection segment in the first... The temperature value is obtained from the temperature response signal in each sampling period. The derivation of this formula is based on the fact that there is a corresponding relationship between the temperature response values ​​of the same spatial detection segment in two adjacent sampling periods. By subtracting the temperature value of the previous sampling period from the temperature value of the current sampling period, the temperature change of the spatial detection segment in the current sampling period can be obtained.

[0048] Given a known sampling time interval, the system further calculates the rate of temperature change within the current sampling period based on the amount of temperature change. This process can be represented by the following formula:

[0049]

[0050] in, Indicates the first The spatial detection segment in the first The rate of temperature change per sampling period, in °C / s; It represents the absolute value of the temperature change, with the unit being °C; This represents the sampling time interval between adjacent sampling periods, measured in seconds (s). The derivation of this formula is based on the fact that, when the sampling time interval is determined, the ratio of the absolute value of the temperature change to the sampling time interval can characterize the degree of temperature change per unit time. This degree of temperature change can be compared with a temperature change rate threshold to help determine whether the temperature change belongs to a valid temperature change.

[0051] As a specific detection process, the temperature value obtained by the 12th spatial detection segment from the temperature response signal in the 18th sampling period. The temperature value was 38.4℃, obtained from the temperature response signal during the 19th sampling period. The temperature was 39.1℃, and the sampling time interval between adjacent sampling periods was [missing information]. The value is 0.5s. Substituting the above data into the formula for calculating temperature change, we get:

[0052]

[0053] Substituting this temperature change into the formula for calculating the rate of temperature change, we get:

[0054]

[0055] In this specific detection process, the temperature change rate threshold was set to 0.8℃ / s, and the number of continuous sampling cycles was set to 3 cycles. Because... The temperature change rate is 1.4℃ / s, which is higher than the temperature change rate threshold of 0.8℃ / s. Furthermore, the 12th spatial detection segment experiences acoustic disturbance in the 19th sampling period. The system determines that the temperature change in this sampling period may be affected by the acoustic disturbance. Therefore, instead of directly using the temperature response signal from the 19th sampling period to update the temperature output, it maintains the previous valid temperature output of the 12th spatial detection segment and temporarily stores the temperature response signal from the 19th sampling period as a temperature signal to be released. Figure 2 As shown, the temperature response values ​​and corresponding temperature change rates of the 18th to 22nd sampling periods are placed in the same detection relationship. The temperature change rate of the 19th sampling period clearly exceeds the rate threshold and corresponds to the acoustic disturbance range, which can intuitively show that the temperature output should not be updated directly in this sampling period.

[0056] When temporarily storing the temperature signal to be released, the system adds a sampling time marker and a disturbance duration marker to the signal. The sampling time marker indicates that the temperature signal was generated in the 19th sampling period, and the disturbance duration marker indicates the duration of the acoustic disturbance corresponding to the temperature signal. Through these markers, the system can combine the generation sequence of the temperature signal and the duration of the acoustic disturbance in subsequent judgments, avoiding the direct discarding of information that may reflect the actual temperature change.

[0057] During the temporary storage of the temperature signal to be released, the system maintains the previous valid temperature output of the 12th spatial detection segment and reduces the participation priority of the 12th spatial detection segment in the temperature continuity judgment of adjacent spatial detection segments. When reducing the participation priority, the system prioritizes the use of adjacent spatial detection segments that are not in an acoustic disturbance state as the basis for temperature continuity judgment, thereby reducing the impact of disturbed spatial detection segments on the surrounding temperature continuity judgment.

[0058] After the acoustic disturbance in the 12th spatial detection segment disappears, the system continues to acquire the temperature response signal of that segment and compares the recovered temperature response signal with the temporarily stored temperature signal to be released in terms of temperature change direction. The temperature change direction includes heating, cooling, and holding directions. The system uses the previous effective temperature output as a reference to determine the change direction of the temperature signal to be released and the recovered temperature response signal. If the recovered temperature response signal matches the temperature change direction of the temperature signal to be released within a preset number of consecutive sampling periods, it indicates that the temporarily stored temperature change during the acoustic disturbance period matches the actual temperature change trend after the disturbance disappears. Figure 3 As shown, the temperature signal to be released in the 19th sampling period is in the temporary storage stage. After recovery from the 20th to the 22nd sampling periods, the continuous sampling signal continues along the heating direction and forms a relationship with the temperature signal to be released in the same direction, thus providing a basis for directional consistency in the temperature output process.

[0059] In this embodiment, after the acoustic disturbance disappears, the recovered temperature values ​​after the 20th, 21st, and 22nd sampling periods are 39.2℃, 39.3℃, and 39.4℃, respectively. The temperature values ​​of these three consecutive sampling periods all maintain a rising direction relative to the temperature value of the 19th sampling period, consistent with the rising direction corresponding to the temperature signal to be released temporarily stored in the 19th sampling period. Therefore, the system supplements the temperature signal to be released temporarily stored in the 19th sampling period into the temperature output process, and after supplementation, restores the participation priority of the 12th spatial detection segment in temperature continuity judgment.

[0060] If multiple temperature signals to be released are generated in the same spatial detection segment within adjacent sampling periods, the system generates a release sequence according to the sampling order. After the acoustic disturbance disappears, the system compares the direction of change of each temperature signal to be released in the release sequence with the recovered temperature response signal. For temperature signals with the same direction of change, the system adds them to the temperature output process according to the sampling order; for temperature signals with different directions of change, the system removes them from the release sequence. Thus, the system can maintain stable temperature output during acoustic disturbances and recover the potentially real temperature change process after the disturbance disappears. Figure 4 As shown, the acoustic disturbance state, temperature output state, signal to be released, and participation priority change synchronously along the sampling period. The 19th sampling period corresponds to the presence of disturbance, output holding, signal temporary storage, and priority reduction. After the 20th sampling period, the disturbance disappears, continuous comparison is performed, update is performed after replenishment, and priority is restored. The timing reflects the coordinated relationship between delayed update, direction confirmation, and output restoration.

[0061] The method described in this embodiment allows the system to synchronously utilize temperature response signals and acoustic response signals within the same sampling period. When the temperature change does not meet the effective temperature change conditions and there is an acoustic disturbance, the system does not directly update the temperature output. Instead, it delays and conditionally releases the temperature output by temporarily storing the temperature signal to be released, marking the sampling time, marking the duration of the disturbance, comparing the direction of the continuous sampling period, and participating in priority adjustment. This improves the stability and reliability of the temperature detection results under acoustic disturbance conditions.

[0062] Example 2:

[0063] This embodiment provides a method for synchronous detection of temperature and acoustic characteristics based on fiber optic sensing, applicable to linearly extended or partitioned test objects within a unit. In implementation, a sensing fiber is deployed along the test object, dividing the corresponding detection area into multiple spatial detection segments. Temperature and acoustic response signals for each spatial detection segment are acquired within the same sampling period. The system determines the temperature change of each spatial detection segment based on the temperature response signal and the acoustic disturbance state of each segment based on the acoustic response signal.

[0064] When acoustic disturbances exist in the current spatial detection segment, the system uses the temperature response changes of adjacent spatial detection segments as a reference. The system first acquires the acoustic disturbance states and temperature changes of spatial detection segments on either side or adjacent to the current spatial detection segment, and then selects the spatial detection segment that is not under acoustic disturbance and whose temperature change direction is consistent with the temperature change direction of the current spatial detection segment before the disturbance as the temperature reference segment. The temperature change direction and magnitude of the temperature reference segment are used to characterize the actual thermal change trend within the adjacent region.

[0065] When acoustic disturbances occur in the current spatial detection segment, the system does not directly update the temperature output based on the temperature response signal of the current spatial detection segment. Instead, it maintains, compensates for, or delays the update of the temperature output of the current spatial detection segment based on the temperature change direction and amplitude of the temperature reference segment. If the temperature change direction of the temperature reference segment is consistent with the temperature change direction of the current spatial detection segment before the disturbance, the previous valid temperature output of the current spatial detection segment is maintained. If the temperature change amplitude of the temperature reference segment indicates a continuous thermal change trend in adjacent areas, the temperature output of the current spatial detection segment is compensated. If the change trend of the temperature reference segment has not yet stabilized, the temperature output update of the current spatial detection segment is delayed.

[0066] When multiple adjacent spatial detection segments sequentially experience acoustic disturbances within different sampling periods, the system records the order in which these disturbances occur. If the temperature change exceeding the effective temperature change condition shifts between adjacent spatial detection segments following the sequence of acoustic disturbance occurrences, it is determined that the temperature change may be caused by the propagation of the acoustic disturbance along its spatial location, and this temperature change is removed from the temperature output process as a suspected disturbance migration temperature change. If the temperature change remains within the same spatial detection segment after the acoustic disturbance disappears, this temperature change is used in the temperature output.

[0067] To characterize the transfer features of acoustic disturbance states between adjacent spatial detection segments, the system can obtain the disturbance transfer rate based on the center position of the spatial detection segment and the sampling period number of the first occurrence of the acoustic disturbance state. This process can be expressed by the following formula:

[0068]

[0069] in, Indicates the acoustic disturbance state from the first The spatial detection segment was transferred to the first... The disturbance transfer rate corresponding to each spatial detection segment is expressed in m / s. Indicates the first The center position of each spatial detection segment, in meters; Indicates the first The center position of each spatial detection segment, in meters; Indicates the first The sampling period number in which the acoustic disturbance state first appears in each spatial detection segment; Indicates the first The sampling period number in which the acoustic disturbance state first appears in each spatial detection segment; This represents the duration of a single sampling period, expressed in seconds (s). The derivation of this formula is based on the fact that the difference in the center positions of adjacent or near spatial detection segments represents the spatial transfer distance of the acoustic disturbance state, and the product of the difference in the sequence numbers of two sampling periods and the duration of a single sampling period represents the transfer time. Dividing the transfer distance by the transfer time yields the disturbance transfer rate.

[0070] As a specific detection process, the center positions of the 30th, 31st, and 32nd spatial detection segments are 15.0m, 15.5m, and 16.0m, respectively. The acoustic disturbance states occur in the 80th, 81st, and 82nd sampling periods, respectively. The duration of a single sampling period is... The value is 0.25s. Taking the 30th and 32nd space detection segments as examples, substituting the above data into the perturbation transfer rate calculation formula, we obtain:

[0071]

[0072] Figure 5 The diagram illustrates the correspondence between the location of acoustic disturbances and the sampling period from the 30th to the 32nd spatial detection segments. The lateral sampling period progresses from the 80th to the 82nd period, and the longitudinal center position progresses from 15.0m to 16.0m. The diagonal lines reflect the path of the sequential transfer of acoustic disturbance states along the spatial detection segments. The 2.0m / s indicated in the figure corresponds to the aforementioned disturbance transfer rate, illustrating that the acoustic disturbance is not fixed in a single spatial detection segment but rather undergoes an orderly migration between adjacent spatial detection segments.

[0073] In this specific detection process, the acoustic disturbance states from the 30th to the 32nd spatial detection segments appear sequentially according to the sampling period. Furthermore, the temperature change exceeding the effective temperature change condition shifts from the 30th to the 32nd spatial detection segment in this order. Based on this, the system determines that this temperature change exhibits characteristics of migrating with the acoustic disturbance state and removes it from the temperature output process as a suspected disturbance migration temperature change to avoid erroneous temperature detection result updates caused by acoustic disturbances. Figure 6 The process is further displayed in the form of a matrix composed of spatial detection segments and sampling periods. The shaded units are distributed sequentially in the 80th period of the 30th segment, the 81st period of the 31st segment, and the 82nd period of the 32nd segment. The candidate temperature change amplitude appears sequentially with the transfer path, indicating that the temperature change has a consistent migration relationship with the acoustic disturbance sequence, and therefore is not used as the basis for temperature output at a stable spatial location.

[0074] As the temperature change shifts between adjacent spatial detection segments in sequence with the occurrence of acoustic disturbances, the system records the temperature change of the corresponding spatial detection segment. After the acoustic disturbance disappears, the system compares the temperature change of the shifted temperature with the temperature change of the spatial detection segment where the acoustic disturbance initially occurred. If the temperature change of the shifted temperature does not persist in the spatial detection segment where the acoustic disturbance initially occurred, it is determined that the temperature change of the shifted temperature does not have a stable spatial correspondence and is removed from the temperature output process.

[0075] If the temperature change remains within the same spatial detection segment after the acoustic disturbance disappears, the system continues to collect temperature changes in that spatial detection segment and its adjacent spatial detection segments, and determines whether the temperature change in the adjacent spatial detection segments forms a continuous transition to that spatial detection segment. To characterize the continuity of temperature change between the target spatial detection segment and its two adjacent spatial detection segments, the system can obtain a difference value for the continuity of temperature change. This process can be expressed by the following formula:

[0076]

[0077] in, Indicates the first The temperature change continuity difference between each spatial detection segment and its two adjacent spatial detection segments is expressed in °C. Indicates the first The range of candidate temperature changes maintained by each spatial detection segment after the acoustic disturbance disappears, in °C; Indicates the first The candidate temperature variation range of each spatial detection segment, in °C; Indicates the first The candidate temperature change range of each spatial detection segment is expressed in °C. The derivation of this formula is based on the fact that the absolute values ​​of the difference between the candidate temperature change ranges of the target spatial detection segment and the adjacent spatial detection segments on both sides are taken, and then the average is calculated. This yields the difference value of the continuity of temperature change between the target spatial detection segment and the adjacent spatial detection segments. The smaller this difference value, the more likely the temperature change of the adjacent spatial detection segments is to form a continuous transition to the target spatial detection segment.

[0078] As another specific detection process, after the acoustic disturbance disappears, the candidate temperature change amplitudes of the 31st, 32nd, and 33rd spatial detection segments are analyzed. , and The values ​​are 0.62℃, 0.65℃, and 0.68℃, respectively. Taking the 32nd spatial detection segment as the target spatial detection segment, substituting the above data into the formula for calculating the continuity difference value of temperature change, we obtain:

[0079]

[0080] In this specific testing process, The value of 0.03℃ indicates that the difference in the candidate temperature change range between the 31st, 32nd and 33rd space detection segments is small, and the temperature change of adjacent space detection segments forms a continuous transition to the 32nd space detection segment. Figure 7 The distribution of candidate temperature change amplitudes for the three adjacent spatial detection segments after the disturbance disappears is shown. The change amplitudes of segments 31, 32, and 33 show a smooth increase along the spatial position. Segment 32 is marked as the target spatial detection segment, and the continuity difference value of 0.03℃ indicates that there are no abrupt changes between this segment and its two adjacent segments. Based on this, the system increases the update priority of the temperature output of the 32nd spatial detection segment and prioritizes determining whether the temperature change of the 32nd spatial detection segment belongs to a real local temperature change process.

[0081] When the update priority of the temperature output of the 32nd spatial detection segment is increased, the system restricts the 32nd spatial detection segment from participating in the processing of invalid temperature changes that occur during acoustic disturbance state transitions within a preset recovery period. If the candidate temperature change amplitude of the 32nd spatial detection segment remains within the preset recovery period, the update priority is maintained; if the candidate temperature change amplitude fails to remain within the 32nd spatial detection segment, the original temperature output priority is restored.

[0082] In this way, when acoustic disturbance states occur sequentially in multiple adjacent spatial detection segments, the system can identify suspected invalid temperature changes that migrate with the acoustic disturbance state by using the disturbance transfer rate, and use the temperature change continuity difference value to confirm the real local temperature changes that remain in the same spatial detection segment after the acoustic disturbance disappears. This improves the continuity and reliability of temperature output in multiple spatial detection segments while suppressing the influence of acoustic disturbances.

Claims

1. A method for simultaneous detection of temperature and acoustic features based on fiber optic sensing, characterized in that, include: A sensing fiber is laid out along the object under test, and the detection area corresponding to the sensing fiber is divided into multiple spatial detection segments. Detection light is injected into the sensing fiber, and the temperature response signal and acoustic response signal of each spatial detection segment are acquired within the same sampling period. The temperature change is obtained based on the temperature response signal, and the acoustic disturbance state is obtained based on the acoustic response signal. The acoustic response signal is used to determine whether there is an acoustic disturbance state caused by vibration, impact, or sound pressure disturbance in the corresponding spatial detection segment. The effective temperature change conditions for each spatial detection segment are set according to the thermal response time of the object under test, the temperature change rate threshold, and the number of continuous sampling periods. The effective temperature change conditions include the correspondence between the temperature change and the temperature change rate threshold, the duration of the temperature change within the continuous sampling period, and the matching between the temperature change and the thermal response time of the object under test. When the temperature change satisfies the effective temperature change condition, the temperature output of the corresponding spatial detection segment is updated; when the temperature change does not satisfy the effective temperature change condition and the acoustic disturbance state exists, the previous effective temperature output is maintained and the update is temporarily suspended; when the temperature change does not satisfy the effective temperature change condition and there are continuous temperature changes in adjacent spatial detection segments, the temperature change is retained for subsequent temperature output, and the temperature detection results of each spatial detection segment and the corresponding acoustic disturbance flag are output; wherein, continuous temperature change refers to adjacent spatial detection segments in adjacent sampling periods or Within a continuous sampling period, the temperature changes have the same or similar directions, and the temperature changes exhibit a continuous transition in spatial location. The temperature change directions include heating, cooling, and holding directions. The system uses the previous effective temperature output of the spatial detection segment as a reference. By calculating the difference between the candidate temperature change amplitudes of the target spatial detection segment and the adjacent spatial detection segments on both sides, taking the absolute value, and then averaging, the continuity difference value of temperature change between the target spatial detection segment and the adjacent spatial detection segments can be obtained. The smaller this difference value, the more likely the temperature change of the adjacent spatial detection segments is to form a continuous transition to the target spatial detection segment.

2. The detection method according to claim 1, characterized in that, When the temperature change in a certain spatial detection segment does not meet the effective temperature change condition and the acoustic disturbance state exists, the temperature response signal of the current sampling period is temporarily stored as a temperature signal to be released. After the acoustic disturbance disappears, if the recovered temperature response signal has the same temperature change direction as the temperature signal to be released, then the temperature signal to be released is added to the temperature output process; otherwise, the temperature signal to be released is removed from the temperature output process.

3. The detection method according to claim 1, characterized in that, When calling the temperature response change status of adjacent spatial detection segments, the adjacent spatial detection segments that are not in the acoustic disturbance state and whose temperature change direction is consistent are selected as temperature reference segments. When the current spatial detection segment is in an acoustic disturbance state, the temperature output of the current spatial detection segment is maintained, compensated, or delayed in updating based on the temperature change direction and temperature change amplitude of the temperature reference segment, so as to maintain the continuity of the temperature output of the current spatial detection segment.

4. The detection method according to claim 1, characterized in that, When multiple adjacent spatial detection segments sequentially exhibit the acoustic disturbance state within different sampling periods, the order in which the acoustic disturbance state occurs is recorded; if the temperature change exceeding the effective temperature change condition shifts between adjacent spatial detection segments according to the order of occurrence, the temperature change is removed from the temperature output process. If the temperature change remains within the same spatial detection segment after the acoustic disturbance disappears, then the temperature change will be used for temperature output.

5. The detection method according to claim 2, characterized in that, The temperature signal to be released is marked with a sampling time mark and a disturbance duration mark; after the acoustic disturbance state disappears, when the recovered temperature response signal is consistent with the temperature change direction of the temperature signal to be released within a preset number of consecutive sampling periods, the temperature signal to be released is added to the temperature output process.

6. The detection method according to claim 2, characterized in that, When multiple release temperature signals are generated in the same spatial detection segment within adjacent sampling periods, a release sequence is generated according to the sampling order. After the acoustic disturbance disappears, the release temperature signals in the release sequence are compared with the recovered temperature response signal in turn according to their change direction. Release temperature signals with the same change direction are added to the temperature output process according to the sampling order, and release temperature signals with different change directions are removed from the release sequence.

7. The detection method according to claim 2, characterized in that, During the temporary storage of the temperature signal to be released, the previous valid temperature output of the corresponding spatial detection segment is maintained, and the participation priority of the corresponding spatial detection segment in the temperature continuity judgment of adjacent spatial detection segments is reduced. The participation priority is used to indicate the degree of adoption of the temperature change of the spatial detection segment in the temperature continuity judgment. When the participation priority is reduced, the system prioritizes the use of adjacent spatial detection segments that are not in an acoustic disturbance state as the judgment basis. After the temperature signal to be released is added to the temperature output process, the participation priority of the corresponding spatial detection segment in the temperature continuity judgment is restored.

8. The detection method according to claim 4, characterized in that, When the temperature change shifts between adjacent spatial detection segments according to the order of occurrence, the migration temperature change of the corresponding spatial detection segment is recorded. The migration temperature change refers to the temperature change that shifts position between adjacent spatial detection segments according to the order of occurrence of the acoustic disturbance state. After the acoustic disturbance state disappears, the migration temperature change is compared with the temperature change of the spatial detection segment where the acoustic disturbance initially occurred. If the migration temperature change does not persist in the spatial detection segment where the acoustic disturbance initially occurred, the migration temperature change is removed from the temperature output process.

9. The detection method according to claim 4, characterized in that, When the temperature change remains within the same spatial detection segment after the acoustic disturbance disappears, the temperature change of the same spatial detection segment and its adjacent spatial detection segments continues to be collected. If the temperature change of adjacent spatial detection segments continuously transitions to the same spatial detection segment, the update priority of the temperature output of the same spatial detection segment is increased. The update priority is used to indicate the order and degree of adoption of the temperature change of the spatial detection segment in the temperature output update judgment. When the update priority is increased, the system prioritizes judging whether the temperature change of the spatial detection segment meets the characteristics of real local temperature change.

10. The detection method according to claim 9, characterized in that, When the update priority of the temperature output of the same spatial detection segment is increased, the same spatial detection segment is restricted from participating in the process of determining the migration of temperature change based on the order of occurrence of the acoustic disturbance state and eliminating invalid temperature change within a preset recovery period. If the temperature change in the same spatial detection segment remains within the same spatial detection segment during the preset recovery period, the update priority is maintained; otherwise, the original temperature output priority is restored.

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