An in-situ observation method for broken wave entrainment in bubble plumes

Abstract

This invention relates to an in-situ observation method for broken wave entrainment bubble plumes. It employs a composite bubble plume sensor combining a bubble panoramic imaging sensor and a ring-array fiber optic probe sensor. The method analyzes the captured omnidirectional images of annular bubbles, using the segmentation profile formed by the difference in spatial resolution between the ring-array fiber optic probe sensor and the annular bubble omnidirectional image to delineate near-field and far-field regions. This allows for the extraction of the spatial distribution characteristics of bubbles in near-field and far-field areas, enabling observation of surface bubble plumes over large areas. Based on the goal of achieving high-resolution "full-area" coverage for large-area detection, and fully considering the resolution limitations of the bubble panoramic imaging sensor in measuring high-density bubble plumes, the ring-array fiber optic probe sensor provides technical compensation, effectively improving the resolution of the observation system and achieving in-situ and high-resolution observation of large-area bubbles.

Description

Technical Field

[0001] This invention relates to an in-situ observation method for broken wave entrainment bubble plumes, belonging to the field of marine hydrological observation technology. Background Technology

[0002] The spatiotemporal distribution and bubble diameter spectrum distribution of broken waves entrained in bubble plumes are not only fundamental data for marine scientific research such as quantifying the influencing factors of the sea-air interface exchange process, studying the generation mechanism of sea salt aerosol particles, exploring the mechanism of sea surface atmospheric kinetics under non-thunderstorm weather, and analyzing the influencing factors of marine remote sensing, but also the basis for marine engineering applications such as marine equipment deployment and bubble curtain technology application.

[0003] Currently, in-situ observations of large-area bubble plumes are mainly conducted offshore using moored buoys or microbuoys deployed from research vessels. These are point-based methods, only able to determine parameters such as the number and velocity of bubble clusters within a small area. Taking the most common offshore observation method, imaging, as an example, limitations imposed by camera installation location mean that only bubble images within the camera's field of view can be acquired. This results in limited data volume per observation, with the captured water volume sample size typically within the cubic millimeter range (e.g., the capture area of ​​the imaging equipment used in SOLAS observations is 20 × 2.9 × 1.9 mm). 3 Furthermore, it is necessary to rely on indirect quantities such as the white crown coverage and the volume flux of bubbles per unit time and per unit area on the sea surface to estimate the average volume flux of bubbles on the sea surface. Finally, large-scale applications can be realized through various theoretical models for calculating air-sea flux. Currently, the observation data of white crown coverage are mostly obtained by non-in-situ observation methods (remote sensing), and its observation accuracy needs to be further improved. The reliability of the theoretical models for calculating air-sea flux has not been verified by observation data. Secondly, regarding the observation of high-density bubble plumes entrained at the moment of wave breaking, most of the existing offshore observations can collect small bubbles (with a particle size of less than 1 mm) that remain in the seawater for several seconds, but rarely focus on high-density bubble plumes entrained at the moment of wave breaking. This type of bubble plume is characterized by rapid spatiotemporal evolution, large size, high porosity, and high density. The Keeling team at the National Center for Atmospheric Research in the United States pointed out that the larger the bubble size, the lower the temperature and humidity of the surrounding air, and the greater the heat exchange and evaporation at the sea-air interface. Large bubbles (with a particle size of more than 0.5 mm) play an indispensable role in the sea-air exchange process, but current technology has not yet been able to conduct offshore observations of high-density bubble plumes entrained at the moment of wave breaking. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide an in-situ observation method for broken wave entrainment into bubble plumes. By applying a composite bubble plume sensor, this method effectively solves the problems of in-situ observation of large-area bubble plumes and observation of high-density bubble plumes entrained by waves at the moment of wave breaking, and realizes large-area, high-resolution in-situ observation of broken wave entrainment into bubble plumes.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention designs an in-situ observation method for broken wave-induced bubble plumes. Based on a bubble panoramic imaging sensor arranged vertically upward on the top surface of the buoy, and a ring array fiber optic probe sensor arranged around the bubble panoramic imaging sensor, a composite bubble plume sensor is constructed. The composite bubble plume sensor is floated on the sea surface with a large number of broken wave-induced bubbles, and the observation of sea surface bubble plumes is realized by following the steps below.

[0006] Step A. Based on the pulse signals received by each element in the ring array fiber probe sensor and the omnidirectional image of the annular bubble captured by the bubble panoramic imaging sensor obtained by synchronous acquisition, calculate the spatial resolution of the ring array fiber probe sensor and the spatial resolution of the annular bubble omnidirectional image.

[0007] Step B. Extract the segmentation profile formed by the difference between the spatial resolution of the ring array fiber probe sensor and the spatial resolution of the ring bubble omnidirectional image;

[0008] Step C. Define the direction inside the segmentation profile as the near-viewing distance region and the direction outside the segmentation profile as the far-viewing distance region. Combine the spatial resolution of the ring array fiber probe sensor and the spatial resolution of the bubble panoramic imaging sensor to calculate the actual sea area corresponding to the near-viewing distance region and the actual sea area corresponding to the far-viewing distance region.

[0009] Step D. Extract bubble parameters from the pulse signals received by each element of the ring-array fiber optic probe sensor, and combine them with the actual sea area corresponding to the near-field region to obtain the spatial distribution characteristics of bubbles in the near-field region; extract bubble images from the omnidirectional map of the ring-shaped bubble using the bubble panoramic imaging sensor, and combine them with the actual sea area corresponding to the far-field region to extract the spatial distribution characteristics of bubbles in the far-field region, thus realizing the observation of surface bubble plumes over a large area of ​​sea.

[0010] As a preferred technical solution of the present invention: In step A, based on the pulse signals received by each element in the ring array fiber optic probe sensor and the annular bubble omnidirectional image captured by the bubble panoramic imaging sensor, the sea area S corresponding to the overlapping closed loop region between the bubble observation imaging area corresponding to the bubble panoramic imaging sensor and the bubble observation imaging area corresponding to the ring array fiber optic probe sensor in the annular bubble omnidirectional image is obtained. Combined with the number of bubbles N1 in the overlapping closed loop region corresponding to the annular bubble omnidirectional image and the number of bubbles N2 extracted from the pulse signals received by each element in the ring array fiber optic probe sensor, the spatial resolution of the bubble panoramic imaging sensor and the spatial resolution of the ring array fiber optic probe sensor are calculated sequentially according to N1 / S and N2 / S.

[0011] As a preferred technical solution of the present invention: step B includes the following steps B1 to B6;

[0012] Step B1. Remove the background from the annular bubble omnidirectional image except for the geometric shapes related to the bubble and array elements, update the annular bubble omnidirectional image to include only the geometric shapes related to the bubble and array elements, and construct an initial annular profile image area containing the geometric shapes related to the bubble and array elements around the center of the annular bubble omnidirectional image. Then initialize the number of known real array element positions in the annular bubble omnidirectional image b=0, and proceed to step B2.

[0013] Step B2. Based on the actual number a of the array elements in the ring array fiber probe sensor, randomly select no less than ab geometric images that have not participated in the processing of steps B3 to B6 in the initial ring profile image area as each geometric image to be analyzed, and then proceed to step B3.

[0014] Step B3. For each geometric image to be analyzed, generate random position points around the geometric image to be analyzed in a circular area with the geometric image to be analyzed as the center and a preset radius. Connect adjacent points to form a series of irregular geometric shape images centered on the array element. Ensure that the initial annular profile image area contains each irregular geometric shape image and bubble image. Then proceed to step B4.

[0015] Step B4. Based on the global target energy function F1(P) corresponding to each standard array element geometric image in the standard annular bubble omnidirectional image captured by the composite bubble plume sensor in a waveless and currentless test tank, and the global target energy function F2(P) corresponding to each irregular geometric shape image in the initial annular profile image area, determine the position of each true array element in the annular bubble omnidirectional image by means of a difference less than a preset similarity threshold, and cumulatively update the number b of the determined true array element positions in the annular bubble omnidirectional image, and then proceed to step B5;

[0016] Step B5. Determine whether the number b of the actual array element positions that have been determined in the annular bubble omnidirectional diagram is equal to a. If yes, proceed to step B6; otherwise, return to step B2.

[0017] Step B6. Based on the determined positions of each real array element in the annular bubble omnidirectional image, construct a target annular profile image area around the center of the annular bubble omnidirectional image, and the image area contains the positions of each real array element. The outer contour of the target annular profile image area is the segmentation profile between the spatial resolution of the bubble panoramic imaging sensor and the spatial resolution of the annular fiber optic probe sensor.

[0018] As a preferred embodiment of the present invention: step B4 includes steps B4-1 to B4-3;

[0019] Step B4-1. Based on the geometric images of each standard array element distinguished in the standard annular bubble omnidirectional image captured by the composite bubble plume sensor in a waveless and currentless test tank, construct a homogeneous function reflecting the consistency of the spectral measurement of the geometric image of each standard array element, and a heterogeneous function reflecting the difference in the spectral measurement of the geometric image of the standard array element. The homogeneous function and the heterogeneous function are added together to form the global target energy function F1(P) that satisfies the Gaussian distribution corresponding to the geometric image of the standard array element. Then, obtain the global target energy function F1(P) corresponding to each geometric image of the standard array element, and then proceed to step B4-2.

[0020] Step B4-2. For each irregular geometric shape image in the initially set annular profile image area, according to step B4-1, obtain the global target energy function F2(P) corresponding to each irregular geometric shape image, and then proceed to step B4-3;

[0021] Step B4-3. For each standard array element geometric image, obtain the difference between the global target energy function F1(P) corresponding to the standard array element geometric image and the global target energy function F2(P) corresponding to each irregular geometric shape image. Determine whether there is a difference less than a preset similarity threshold. If so, the irregular geometric shape image corresponding to each difference is determined as the real array element position in the annular bubble omnidirectional image, and the number b of the real array element positions already determined in the annular bubble omnidirectional image is cumulatively updated. Otherwise, there are no real array element positions, and then proceed to step B5.

[0022] As a preferred technical solution of the present invention: In step D, after denoising the signals received by each array element in the ring array fiber probe sensor, the detection bubble signal is obtained by extracting the pulse signal, a bubble signal recognition model is established, and based on the normalization processing of the detection bubble signal, the similarity detection between the detection bubble signal and the bubble signal recognition model signal is performed to realize bubble quantity statistics, bubble size statistics, bubble movement speed statistics, and bubble porosity statistics, thus completing the extraction of bubble parameters.

[0023] As a preferred technical solution of the present invention: In step D, for the image of the far-viewing distance region outside the segmentation profile in the omnidirectional image of the annular bubble, grayscale processing, binarization processing, filtering processing, hole filling morphology processing, edge detection and quantity statistics processing are performed in sequence. Then, combined with the actual sea area corresponding to the far-viewing distance region, the spatial distribution characteristics of the far-viewing distance sea bubble are obtained.

[0024] Corresponding to the above, the technical problem to be solved by the present invention is to provide a device for in-situ observation of broken wave entrained bubble plumes. Specifically, a bubble panoramic imaging sensor is designed, a composite bubble plume sensor is constructed, and high-density bubble plume information within the near-view distance range and panoramic images of bubble plumes within the far-view distance and wide-angle range are acquired simultaneously, so as to efficiently complete the designed in-situ observation method of bubble plumes.

[0025] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention designs a device for in-situ observation of broken wave entrained bubble plumes, including a composite bubble plume sensor. The composite bubble plume sensor includes a panoramic bubble imaging sensor comprising a parabolic reflector, a support rod, an image acquisition circuit board, a ring-shaped imaging detector, and a transparent protective cover. The image acquisition circuit board is placed on the upper surface of the float in the composite bubble plume sensor. One end of the support rod is placed at the center of the image acquisition circuit board and is perpendicular to the image acquisition circuit board. The bottom of the outer surface of the parabolic reflector is connected to the other end of the support rod, and the opening of the parabolic reflector is vertically upward. The transparent protective cover is arranged around the periphery of the support rod, and the top edge of the transparent protective cover is connected to the periphery of the parabolic reflector. The bottom edge of the transparent protective cover is connected to the image acquisition circuit board. The ring-shaped imaging detector is located inside the transparent protective cover and is fitted inside the support rod. The photosensitive direction of the ring-shaped imaging detector points towards the parabolic reflector, and the photoelectric image signal acquired by the ring-shaped imaging detector is connected to the image acquisition circuit board.

[0026] As a preferred technical solution of the present invention: the bubble panoramic imaging sensor also includes a top cover and a satellite communication module. The support rod has two open ends and is interconnected. The top cover is set on the opening of the parabolic reflector. The satellite communication module is set on the upper surface of the top cover. The satellite communication module connection signal line is connected to the image acquisition circuit board through the inside of the support rod.

[0027] The in-situ observation method for broken wave entrainment bubble plumes described in this invention, compared with existing technologies, has the following technical advantages:

[0028] This invention presents an in-situ observation method for broken wave entrainment bubble plumes. It employs a composite bubble plume sensor, combining a panoramic bubble imaging sensor and a ring-array fiber optic probe sensor, to analyze the captured omnidirectional images of annular bubbles. The method uses the segmentation profile formed by the difference in spatial resolution between the ring-array fiber optic probe sensor and the annular bubble omnidirectional image to delineate near-field and far-field regions. This allows for the extraction of the spatial distribution characteristics of bubbles in near-field and far-field areas, enabling observation of surface bubble plumes over large areas. Based on the goal of achieving high-resolution "full-area" coverage for large-area detection, and fully considering the resolution limitations of panoramic bubble imaging sensors in measuring high-density bubble plumes, a ring-array fiber optic probe sensor is used for technical compensation, effectively improving the resolution of the observation system and achieving in-situ and high-resolution observation of large-area bubbles. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the in-situ observation method for broken wave entrainment bubble plumes designed in this invention.

[0030] Figure 2 This is a side view schematic diagram of the composite bubble plume sensor designed in this invention;

[0031] Figure 3 This is a schematic diagram illustrating the structure and application of the bubble panoramic imaging sensor in the composite bubble plume sensor designed in this invention. Detailed Implementation

[0032] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] The present invention proposes an in-situ observation method for broken wave-induced bubble plumes, which uses a composite bubble plume sensor designed in combination to float on the sea surface where there are a large number of broken wave-induced bubbles, thereby realizing the observation of sea surface bubble plumes.

[0034] like Figure 2 As shown, the composite bubble plume sensor includes a bubble panoramic imaging sensor arranged vertically upwards from the top surface of the buoy, and a ring array of fiber optic probe sensors arranged around the bubble panoramic imaging sensor, wherein, as... Figure 3 As shown, the bubble panoramic imaging sensor includes a parabolic reflector, a support rod, an image acquisition circuit board, a ring-shaped imaging detector, and a transparent protective cover. The image acquisition circuit board is placed on the upper surface of the float in the composite bubble plume sensor. One end of the support rod is located at the center of the image acquisition circuit board and is perpendicular to it. The bottom of the outer surface of the parabolic reflector is connected to the other end of the support rod, and the opening of the parabolic reflector is vertically upward. The transparent protective cover is arranged around the perimeter of the support rod, with its top edge connected to the perimeter of the parabolic reflector and its bottom edge connected to the image acquisition circuit board. The ring-shaped imaging detector is located inside the transparent protective cover and is fitted around the support rod. The light-sensing direction of the ring-shaped imaging detector points towards the parabolic reflector, and the photoelectric image signal acquired by the ring-shaped imaging detector is connected to the image acquisition circuit board.

[0035] In practical applications, both the bubble panoramic imaging sensor and the ring-array fiber optic probe sensor have bubble data processing circuit compartments designed within the buoy body. These compartments house the bubble data processing circuitry. The output signals from both the image acquisition circuit board and the ring-array fiber optic probe sensor are connected to this bubble data processing circuit. The in-situ observation method for broken wave-induced bubble plumes designed in this invention, in practical applications, involves floating the composite bubble plume sensor on a sea surface with a large number of broken wave-induced bubbles, as follows... Figure 1 As shown, specific steps A to D are performed to achieve the observation of sea surface bubble plumes.

[0036] Step A. Based on the pulse signals received by each element in the ring array fiber optic probe sensor and the omnidirectional image of the ring bubble captured by the bubble panoramic imaging sensor obtained through synchronous acquisition, as shown... Figure 3 As shown, for the overlapping closed-loop region between the bubble observation imaging area corresponding to the bubble panoramic imaging sensor and the bubble observation imaging area corresponding to the ring array fiber optic probe sensor in the annular bubble omnidirectional image, the sea area S corresponding to the overlapping closed-loop region is obtained. Combined with the number of bubbles N1 in the overlapping closed-loop region corresponding to the annular bubble omnidirectional image and the number of bubbles N2 extracted from the pulse signals received by each array element in the ring array fiber optic probe sensor, the spatial resolution of the bubble panoramic imaging sensor and the spatial resolution of the ring array fiber optic probe sensor are calculated sequentially according to N1 / S and N2 / S.

[0037] Step B. Extract the segmentation profile formed by the difference between the spatial resolution of the ring array fiber probe sensor and the spatial resolution of the annular bubble omnidirectional image. In practical applications, the specific design is to execute steps B1 to B6 as follows.

[0038] Step B1. Remove the background from the annular bubble omnidirectional image except for the geometric shapes related to the bubble and array elements, update the annular bubble omnidirectional image to include only the geometric shapes related to the bubble and array elements, and construct an initial annular profile image area containing the geometric shapes related to the bubble and array elements around the center of the annular bubble omnidirectional image. Then initialize the number of known real array element positions in the annular bubble omnidirectional image b = 0, and proceed to step B2.

[0039] Step B2. Based on the actual number 'a' of the array elements in the ring array fiber probe sensor, randomly select no less than 'ab' geometric images that were not processed in steps B3 to B6 from the initial ring profile image area as the geometric images to be analyzed, and then proceed to step B3.

[0040] Step B3. For each geometric image to be analyzed, generate random position points around the geometric image in a circular region with the geometric image to be analyzed as the center and a preset radius. Connect adjacent points to form a series of irregular geometric shape images centered on the array element. Ensure that the initial annular profile image area contains each irregular geometric shape image and bubble image. Then proceed to step B4.

[0041] Step B4. Based on the global target energy function F1(P) corresponding to each standard array element geometric image in the standard annular bubble omnidirectional image captured by the composite bubble plume sensor in a waveless and currentless test tank, and the global target energy function F2(P) corresponding to each irregular geometric shape image in the initial annular profile image area, determine the position of each true array element in the annular bubble omnidirectional image by means of a difference less than a preset similarity threshold, and cumulatively update the number b of the determined true array element positions in the annular bubble omnidirectional image, and then proceed to step B5.

[0042] In practical applications, step B4 above is specifically designed and executed as follows: steps B4-1 to B4-3.

[0043] Step B4-1. Based on the geometric images of each standard array element distinguished in the standard annular bubble omnidirectional image captured by the composite bubble plume sensor in a waveless and currentless test tank, construct a homogeneous function reflecting the consistency of the spectral measurement of the geometric image of each standard array element, and a heterogeneous function reflecting the difference in the spectral measurement of the geometric image of the standard array element. The homogeneous function and the heterogeneous function are added together to form the global target energy function F1(P) that satisfies the Gaussian distribution corresponding to the geometric image of the standard array element. Then, obtain the global target energy function F1(P) corresponding to each geometric image of the standard array element, and then proceed to step B4-2.

[0044] Step B4-2. For each irregular geometric shape image in the initially set annular profile image area, according to step B4-1, obtain the global target energy function F2(P) corresponding to each irregular geometric shape image, and then proceed to step B4-3.

[0045] Step B4-3. For each standard array element geometric image, obtain the difference between the global target energy function F1(P) corresponding to the standard array element geometric image and the global target energy function F2(P) corresponding to each irregular geometric shape image. Determine whether there is a difference less than a preset similarity threshold. If so, the irregular geometric shape image corresponding to each difference is determined as the real array element position in the annular bubble omnidirectional image, and the number b of the real array element positions already determined in the annular bubble omnidirectional image is cumulatively updated. Otherwise, there are no real array element positions, and then proceed to step B5.

[0046] Step B5. Determine whether the number b of the actual array element positions that have been determined in the annular bubble omnidirectional diagram is equal to a. If yes, proceed to step B6; otherwise, return to step B2.

[0047] Step B6. Based on the determined positions of each real array element in the annular bubble omnidirectional image, construct a target annular profile image area around the center of the annular bubble omnidirectional image, and the image area contains the positions of each real array element. The outer contour of the target annular profile image area is the segmentation profile between the spatial resolution of the bubble panoramic imaging sensor and the spatial resolution of the annular fiber optic probe sensor.

[0048] Step C. Define the direction inside the segmentation profile as the near-viewing distance region and the direction outside the segmentation profile as the far-viewing distance region. Combine the spatial resolution of the ring array fiber probe sensor and the spatial resolution of the bubble panoramic imaging sensor to calculate the actual sea area corresponding to the near-viewing distance region and the actual sea area corresponding to the far-viewing distance region.

[0049] Step D. Extract bubble parameters from the pulse signals received by each element of the ring-array fiber optic probe sensor, and combine them with the actual sea area corresponding to the near-field region to obtain the spatial distribution characteristics of bubbles in the near-field region; extract bubble images from the omnidirectional map of the ring-shaped bubble using the bubble panoramic imaging sensor, and combine them with the actual sea area corresponding to the far-field region to extract the spatial distribution characteristics of bubbles in the far-field region, thus realizing the observation of surface bubble plumes over a large area of ​​sea.

[0050] Specifically, after denoising the signals received by each element in the ring-array fiber optic probe sensor, the detection bubble signal is obtained by extracting the pulse signal, a bubble signal recognition model is established, and based on the normalization processing of the detection bubble signal, the similarity detection between the detection bubble signal and the bubble signal recognition model signal is performed to realize bubble quantity statistics, bubble size statistics, bubble movement speed statistics, and bubble porosity statistics, thus completing the extraction of bubble parameters.

[0051] Furthermore, for images in the omnidirectional map of annular bubbles where the direction outside the segmentation profile is the far-viewing distance region, grayscale processing, binarization processing, filtering processing, hole filling morphology processing, edge detection and quantity statistics processing are performed sequentially. Then, combined with the actual sea area corresponding to the far-viewing distance region, the spatial distribution characteristics of bubbles in the far-viewing distance sea area are obtained.

[0052] Regarding the designed composite bubble plume sensor, in practical applications, such as... Figure 3 As shown, the further design of the bubble panoramic imaging sensor also includes a top cover and a satellite communication module. The support rod has two open ends that are interconnected. The top cover is set on the opening of the parabolic reflector, and the satellite communication module is set on the upper surface of the top cover. The satellite communication module's signal line is connected to the image acquisition circuit board through the inside of the support rod. In practical applications, the ring array fiber optic probe sensor is set on the buoy body, adopting a structure with multiple uniformly distributed through holes. It uses a screwless connection method and is made of aluminum alloy, which has a lower density than stainless steel and is non-magnetic, effectively avoiding interference problems. The satellite communication module uses a Beidou satellite antenna, and the bubble data processing circuit and Beidou antenna circuit are made of ABS plastic to effectively avoid electromagnetic interference problems.

[0053] This invention designs an in-situ observation method for broken wave entrainment in bubble plumes, applying it in practice. Based on a large-area observation method, it further incorporates in-situ observation and improves the resolution of the large-area in-situ observation method. The large-area in-situ observation method uses a bubble panoramic imaging sensor as its core, fully utilizing the advantage of catadioptric panoramic imaging in achieving wide-angle imaging. It innovatively selects a retina-like imaging device with non-uniform pixel distribution as the sensor's imaging detector, effectively solving the problem of existing catadioptric panoramic imaging methods that suffer from radial resolution non-uniformity (the number of samplings gradually decreases from the outer ring to the inner ring of the same radial span), resulting in fewer sampling times for the bubble panoramic image and thus failing to capture the inner ring of the bubble. The problem of accurately reconstructing the panoramic image of the bubble surface is addressed through in-situ observation. The in-situ observation method uses a miniature buoy as the platform for the bubble panoramic imaging sensor, effectively avoiding the low spatial resolution drawbacks of non-in-situ observation methods such as remote sensing and survey vessels. Furthermore, to improve the resolution of large-area in-situ observation, a ring-array fiber optic probe sensor is employed. Multiple fiber optic probe sensors are evenly distributed in an array on the buoy, fully utilizing the characteristic of fiber optic probe sensors to penetrate bubble plumes within the near-field range to obtain microscopic bubble features. This effectively fills the "observation blind zone" where image methods suffer from severe ghosting in high-density bubble plumes within the near-field range, achieving the goal of improving the resolution of large-area observations. In addition, methods to improve resolution, in conjunction with the designed observation approach, include a data fusion method combining bubble panoramic imaging sensor-acquired bubble images and ring-array fiber optic probe sensor-captured bubble information. This includes extracting the spatial resolution "watershed" profile of the panoramic sensor and the ring-array fiber optic probe sensor, extracting the spatial distribution characteristics of bubbles in the far-field area in the second step, and extracting the spatial distribution characteristics of bubbles in the near-field area in the third step.

[0054] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for in-situ observation of broken wave entrainment in bubble plumes, characterized in that: A composite bubble plume sensor is constructed by combining a bubble panoramic imaging sensor deployed vertically upward on the top surface of the buoy and a ring array fiber optic probe sensor deployed around the bubble panoramic imaging sensor. The composite bubble plume sensor is floated on the sea surface where a large number of bubbles are induced by breaking waves. The following steps are followed to observe the bubble plume on the sea surface. Step A. Based on the pulse signals received by each element in the ring array fiber optic probe sensor and the omnidirectional image of the annular bubble captured by the bubble panoramic imaging sensor, the sea area S corresponding to the overlapping closed loop region between the bubble observation imaging area corresponding to the bubble panoramic imaging sensor and the bubble observation imaging area corresponding to the ring array fiber optic probe sensor in the annular bubble omnidirectional image is obtained. Combined with the number of bubbles N1 in the overlapping closed loop region corresponding to the annular bubble omnidirectional image and the number of bubbles N2 extracted from the pulse signals received by each element in the ring array fiber optic probe sensor, the spatial resolution of the bubble panoramic imaging sensor and the spatial resolution of the ring array fiber optic probe sensor are calculated sequentially according to N1 / S and N2 / S. Step B. Extract the segmentation profile formed by the difference between the spatial resolution of the ring array fiber probe sensor and the spatial resolution of the ring bubble omnidirectional image, including the following steps B1 to B6; Step B1. Remove the background from the annular bubble omnidirectional image except for the geometric shapes related to the bubble and array elements, update to obtain an annular bubble omnidirectional image that only contains the geometric shapes related to the bubble and array elements, and construct an initial annular profile image area containing the geometric shapes related to the bubble and array elements around the center of the annular bubble omnidirectional image. Then initialize the number of known real array element positions in the annular bubble omnidirectional image b=0, and proceed to step B2. Step B2. Based on the actual number a of the array elements in the ring array fiber probe sensor, randomly select no less than ab geometric images that have not participated in the processing of steps B3 to B6 in the initial ring profile image area as each geometric image to be analyzed, and then proceed to step B3. Step B3. For each geometric image to be analyzed, generate random position points around the geometric image to be analyzed in a circular area with the geometric image to be analyzed as the center and a preset radius. Connect adjacent points to form a series of irregular geometric shape images centered on the array element. Ensure that the initial annular profile image area contains each irregular geometric shape image and bubble image, and then proceed to step B4. Step B4. Based on the global target energy function F1(P) corresponding to each standard array element geometric image in the standard annular bubble omnidirectional image captured by the composite bubble plume sensor in a waveless and currentless test tank, and the global target energy function F2(P) corresponding to each irregular geometric shape image in the initial annular profile image area, determine the position of each true array element in the annular bubble omnidirectional image by means of a difference less than a preset similarity threshold, and cumulatively update the number b of the determined true array element positions in the annular bubble omnidirectional image, and then proceed to step B5; Step B5. Determine whether the number b of the actual array element positions that have been determined in the annular bubble omnidirectional diagram is equal to a. If yes, proceed to step B6; otherwise, return to step B2. Step B6. Based on the determined positions of each real array element in the annular bubble omnidirectional image, construct a target annular profile image area around the center of the annular bubble omnidirectional image, and the image area contains the positions of each real array element. The outer contour of the target annular profile image area is the segmentation profile between the spatial resolution of the bubble panoramic imaging sensor and the spatial resolution of the annular fiber probe sensor. Step C. Define the direction inside the segmentation profile as the near-viewing distance region and the direction outside the segmentation profile as the far-viewing distance region. Combine the spatial resolution of the ring array fiber probe sensor and the spatial resolution of the bubble panoramic imaging sensor to calculate the actual sea area corresponding to the near-viewing distance region and the actual sea area corresponding to the far-viewing distance region. Step D. Extract bubble parameters from the pulse signals received by each element of the ring-array fiber optic probe sensor, and combine them with the actual sea area corresponding to the near-field region to obtain the spatial distribution characteristics of bubbles in the near-field region; extract bubble images from the annular bubble omnidirectional map acquired by the bubble panoramic imaging sensor, and combine them with the actual sea area corresponding to the far-field region to extract the spatial distribution characteristics of bubbles in the far-field region, thereby realizing the observation of surface bubble plumes over a large area of ​​sea.

2. The in-situ observation method for broken wave entrainment bubble plumes according to claim 1, characterized in that: Step B4 includes steps B4-1 to B4-3; Step B4-1. Based on the geometric images of each standard array element distinguished in the standard annular bubble omnidirectional image captured by the composite bubble plume sensor in a waveless and currentless test tank, construct a homogeneous function reflecting the consistency of the spectral measurement of the geometric image of each standard array element, and a heterogeneous function reflecting the difference in the spectral measurement of the geometric image of the standard array element. The homogeneous function and the heterogeneous function are added together to form the global target energy function F1(P) that satisfies the Gaussian distribution corresponding to the geometric image of the standard array element; then obtain the global target energy function F1(P) corresponding to each geometric image of the standard array element, and then proceed to step B4-2; Step B4-2. For each irregular geometric shape image in the initially set annular profile image area, according to step B4-1, obtain the global target energy function F2(P) corresponding to each irregular geometric shape image, and then proceed to step B4-3; Step B4-3. For each standard array element geometric image, obtain the difference between the global target energy function F1(P) corresponding to the standard array element geometric image and the global target energy function F2(P) corresponding to each irregular geometric shape image. Determine whether there is a difference less than the preset similarity threshold. If so, the irregular geometric shape image corresponding to each difference is determined as the real array element position in the annular bubble omnidirectional image, and the number b of the real array element positions already determined in the annular bubble omnidirectional image is cumulatively updated. Otherwise, there are no real array element positions, and then proceed to step B5.

3. The in-situ observation method for broken wave entrainment bubble plumes according to claim 1, characterized in that: In step D, after denoising the signals received by each element in the ring array fiber probe sensor, the detection bubble signal is obtained by extracting the pulse signal, a bubble signal recognition model is established, and based on the normalization processing of the detection bubble signal, the similarity detection between the detection bubble signal and the bubble signal recognition model signal is performed to realize bubble quantity statistics, bubble size statistics, bubble movement speed statistics, and bubble porosity statistics, thus completing the extraction of bubble parameters.

4. The in-situ observation method for broken wave entrainment bubble plumes according to claim 1, characterized in that: In step D, for the image of the far-viewing distance region in the omnidirectional map of the annular bubble, grayscale processing, binarization processing, filtering processing, hole filling morphology processing, edge detection and quantity statistics processing are performed in sequence. Then, combined with the actual sea area corresponding to the far-viewing distance region, the spatial distribution characteristics of the far-viewing distance sea bubble are obtained.

5. An apparatus for in-situ observation of a broken wave entrainment bubble plume as described in any one of claims 1 to 4, characterized in that: The system includes a composite bubble plume sensor. The bubble panoramic imaging sensor within the composite bubble plume sensor comprises a parabolic reflector, a support rod, an image acquisition circuit board, a ring-shaped imaging detector, and a transparent protective cover. The image acquisition circuit board is positioned on the upper surface of the float in the composite bubble plume sensor. One end of the support rod is located at the center of the image acquisition circuit board, and the support rod is perpendicular to the image acquisition circuit board. The bottom of the outer surface of the parabolic reflector is connected to the other end of the support rod, and the opening of the parabolic reflector faces vertically upwards. The transparent protective cover is arranged around the perimeter of the support rod, with its top edge connected to the perimeter of the parabolic reflector and its bottom edge connected to the image acquisition circuit board. The ring-shaped imaging detector is located inside the transparent protective cover and is fitted around the support rod. The photosensitive direction of the ring-shaped imaging detector points towards the parabolic reflector, and the photoelectric image signal acquired by the ring-shaped imaging detector is connected to the image acquisition circuit board.

6. The apparatus according to claim 5, characterized in that: The bubble panoramic imaging sensor also includes a top cover and a satellite communication module. The support rod is open at both ends and interconnected. The top cover is set on the opening of the parabolic reflector. The satellite communication module is set on the upper surface of the top cover. The satellite communication module's signal line is connected to the image acquisition circuit board through the inside of the support rod.

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