A method for testing particle size distribution of mineral fire retardant powder

Abstract

The present invention relates to the technical field of testing particle size, and specifically to a method for testing the particle size distribution of mineral fireproof powder. The present invention obtains the dispersion degree of the fireproof powder in the sliding window according to the morphological characteristics of the connected domain of particles in the sliding window; in the light spot connected domain of the sliding window, according to the gradient characteristics of the light spot edge pixel points in different pixel neighborhood windows, the blur degree of the light spot edge of the corresponding sliding window is obtained; according to the brightness distribution of different light spot pixel points in the sliding window, the brightness difference evaluation of the sliding window is obtained; the illumination uniformity of the sliding window is obtained, and the corrected light scattering intensity of each sliding window at each angle is obtained in combination with the initial light scattering intensity corresponding to each sliding window at different angles, and the overall light scattering intensity of each fireproof powder particle is obtained; the fireproof powder particles are tested for particle size distribution. The present invention improves the accuracy of particle size distribution by obtaining the accurate light scattering intensity of each fireproof powder particle.

Description

Technical Field

[0001] The invention relates to the technical field of testing particle size, and in particular to a method for testing the particle size distribution of mineral fireproof powder. Background Art

[0002] Particle size distribution is a very important physical property for the application performance of fire retardant powder. The particle size directly affects the fluidity, miscibility and thermal conductivity of the material in a high temperature environment. Therefore, in order to ensure the improvement of product quality, it is necessary to accurately analyze and control the particle size distribution of mineral fire retardant powder.

[0003] In the prior art, the particle size distribution of mineral fire retardant powder is tested by laser particle size analysis, which can provide a fine particle size distribution map and identify subtle particle differences in the sample; however, due to the influence of other light sources, the laser beam irradiation is uneven, which affects the detection of scattered light, and thus affects the fire retardant powder particle size distribution test, resulting in poor accuracy of the particle size distribution test. Summary of the invention

[0004] In order to solve the technical problem that the irradiation of the laser beam is uneven due to the influence of other light sources and the particle size distribution test has poor accuracy, the purpose of the present invention is to provide a method for testing the particle size distribution of mineral fire retardant powder. The technical scheme adopted is as follows: The present invention provides a method for testing the particle size distribution of mineral fire retardant powder, the method comprising: Obtaining images of fire retardant powder particles at different angles and the corresponding initial light scattering intensity; For any angle, a sliding window is constructed to traverse the image of the fire retardant powder particles, and the particle connected domain and the light spot connected domain in each sliding window are obtained; for any sliding window, the particle exposure degree of the sliding window is obtained according to the morphological characteristics of the particle connected domain in the sliding window; the fire retardant powder dispersion degree of the sliding window is obtained according to the distribution of the particle connected domain in the sliding window and the particle exposure degree; In the light spot connected domain of the sliding window, the pixel neighborhood window corresponding to each light spot edge pixel point is obtained; the blur degree of the light spot edge of the corresponding sliding window is obtained according to the gradient characteristics of the light spot edge pixel points in different pixel neighborhood windows; the brightness difference evaluation of the sliding window is obtained according to the brightness distribution of different light spot pixel points in the sliding window; the illumination uniformity of the sliding window is obtained according to the dispersion degree of fire retardant powder, blur degree of light spot edge and brightness difference evaluation of the sliding window; According to the initial light scattering intensity corresponding to each sliding window at different angles and the irradiation uniformity, the corrected light scattering intensity of each sliding window at each angle is obtained, and the overall light scattering intensity of each fire retardant powder particle is obtained; The particle size distribution of the fire retardant powder particles is tested according to the overall light scattering intensity.

[0005] Furthermore, the method for acquiring the particle connected domain and the light spot connected domain includes: A connected domain detection algorithm is used to obtain multiple connected domains of each sliding window; Obtain the average brightness value of all pixels in each connected domain as the local brightness level; obtain the average local brightness level in all connected domains as the overall brightness level; obtain the brightness fluctuation degree of the pixels in all connected domains as the brightness fluctuation value; obtain the sum of the overall brightness level and the preset multiple of the brightness fluctuation value as the brightness reference value; If the local brightness level of the connected domain is greater than or equal to the brightness reference value, the corresponding connected domain is regarded as the light spot connected domain, and the other connected domains except the light spot connected domain are regarded as particle connected domains.

[0006] Furthermore, the method for obtaining the particle exposure degree includes: Construct the maximum enclosing rectangle of each particle connected domain; Obtaining a ratio of the number of pixels in each particle connected domain to the number of pixels in the maximum circumscribed rectangle as a first ratio; The accumulated value of the first ratio corresponding to all particle connected domains in each sliding window is obtained as the particle exposure degree.

[0007] Furthermore, the method for obtaining the dispersion degree of the fire retardant powder includes: Obtain the ratio of the number of connected domains of particles to the number of pixels in each sliding window as the particle density of each sliding window; The ratio of the particle exposure degree to the particle density degree of each sliding window is obtained as the dispersion degree of the fire retardant powder in each sliding window.

[0008] Furthermore, the method for obtaining the blur degree of the light spot edge includes: Obtain the sum of the gradients of all the pixels at the edge of the light spot in each pixel neighborhood window as the local gradient level; The blur degree of the light spot edge of the sliding window is obtained according to the fluctuation degree of the local gradient level of different pixel neighborhood windows in the sliding window. The fluctuation degree of the local gradient level is negatively correlated with the blur degree of the light spot edge.

[0009] Furthermore, the method for obtaining the brightness-darkness difference evaluation includes: The difference between the maximum brightness and the minimum brightness of the light spot pixel in the sliding window is obtained as the brightness difference evaluation of the sliding window.

[0010] Furthermore, the method for obtaining the illumination uniformity includes: A negative correlation mapping is performed on the brightness and darkness difference evaluation of the sliding window as the first uniformity coefficient; The first uniformity coefficient of the sliding window, the blurring degree of the light spot edge and the dispersion degree of the fire retardant powder are integrated to serve as the illumination uniformity of the sliding window.

[0011] Furthermore, the method for obtaining the corrected light scattering intensity includes: According to the illumination uniformity of the sliding window at different angles, the normal illumination window and the abnormal illumination window at each angle are screened out; For any angle, if the sliding window is an abnormal illumination window, obtain the normal illumination window corresponding to the abnormal illumination window at other angles as the target window; obtain the mean of the illumination uniformity of all target windows as the first mean; obtain the mean of the initial light scattering intensity of all target windows at the corresponding angles as the second mean; obtain the ratio of the first mean to the illumination uniformity of the abnormal illumination window at the corresponding angle, and calculate the product between the ratio result and the second mean as the corrected intensity weight; Obtaining the sum of the initial light scattering intensity and the corrected intensity weight at the corresponding angle of each abnormal illumination window as the corrected light scattering intensity of each abnormal illumination window at the corresponding angle; If the sliding window is a normal illumination window, the initial light scattering intensity at the corresponding angle of the sliding window is used as the corrected light scattering intensity.

[0012] Furthermore, the screening out of the normal illumination window and the abnormal illumination window at each angle includes: For any angle, if the illumination uniformity of the sliding window is less than the preset uniformity threshold, the corresponding sliding window is regarded as an abnormal illumination window; if the illumination uniformity of the sliding window is greater than or equal to the preset uniformity threshold, the corresponding sliding window is regarded as a normal illumination window.

[0013] Furthermore, the method for obtaining the overall light scattering intensity includes: Obtaining a ratio of the corrected light scattering intensity to the initial light scattering intensity of each sliding window at each angle as an intensity ratio; Calculate the product of the initial light scattering intensity of the sliding window at the corresponding angle of each fire retardant powder particle and the intensity ratio as the local light scattering intensity of the sliding window at the corresponding angle of each fire retardant powder particle; The corrected light scattering intensity of the sliding window of the same fire retardant powder particle at different angles is averaged to be the overall light scattering intensity of each fire retardant powder particle.

[0014] The present invention has the following beneficial effects: The present invention constructs a sliding window to traverse the fireproof powder particle image at any angle, obtains the particle connected domain and the light spot connected domain in each sliding window, and can systematically and without omission traverse the entire image by means of the sliding window, ensuring that each fireproof powder particle and the light spot information around it are captured; for any sliding window, the morphological characteristics and distribution of the particle connected domain in the sliding window are analyzed to obtain the fireproof powder dispersion degree of the sliding window; in the light spot connected domain of the sliding window, a pixel neighborhood window corresponding to each light spot edge pixel point is obtained, so that the subtle features of the light spot edge can be captured more accurately; considering that the softer the light spot is, the more blurred the light spot edge is, according to the gradient characteristics of the light spot edge pixel points in different pixel neighborhood windows, the blurring degree of the light spot edge of the corresponding sliding window is obtained, and the gradient characteristics are analyzed to reflect the change of the brightness or color intensity of the light spot edge pixel points, and the blurring degree of the light spot edge is quantified; according to the brightness distribution of different light spot pixel points in the sliding window, the brightness difference evaluation of the sliding window is obtained, reflecting the sliding window The uniformity of brightness distribution of the light spot in the middle; the uniformity of illumination of the sliding window is obtained according to the dispersion degree of fire retardant powder in the sliding window, the blur degree of the edge of the light spot, and the difference between light and dark, avoiding the one-sidedness that may be caused by a single indicator, and improving the accuracy and reliability of the evaluation; according to the initial light scattering intensity corresponding to each sliding window at different angles, and the uniformity of illumination, the corrected light scattering intensity of each sliding window at each angle is obtained, and the overall light scattering intensity of each fire retardant powder particle is obtained, taking into account the influence of the uniformity of illumination, and more accurately reflecting the light scattering characteristics of the particles; the particle size distribution of the fire retardant powder particles is tested. The present invention improves the accuracy of the particle size distribution by obtaining the accurate initial light scattering intensity of each fire retardant powder particle. The present invention obtains the accurate light scattering intensity of each fire retardant powder particle and improves the accuracy of the particle size distribution by taking into account the influence of uneven laser beam illumination. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A flow chart of a method for testing particle size distribution of mineral fire retardant powder provided by one embodiment of the present invention; Figure 2 A flow chart of a method for acquiring a particle connected domain and a light spot connected domain provided by an embodiment of the present invention; Figure 3A flow chart of a method for obtaining corrected light scattering intensity provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a method for testing the particle size distribution of a mineral fire retardant powder proposed by the present invention, its specific implementation, structure, characteristics and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0018] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0019] The specific scheme of the method for testing the particle size distribution of mineral fire retardant powder provided by the present invention is described in detail below with reference to the accompanying drawings.

[0020] See also Figure 1 , which shows a flow chart of a method for testing particle size distribution of mineral fire retardant powder provided by an embodiment of the present invention, and the specific method includes: Step S1: Acquire images of fire retardant powder particles at different angles and the corresponding initial light scattering intensities.

[0021] In the embodiment of the present invention, considering that the laser beam is unevenly irradiated, resulting in poor accuracy of the particle size distribution test, it is necessary to analyze the irradiation conditions at different angles and correct the initial light scattering intensity; first, a dispersant or a dispersion liquid is added to the fire retardant powder sample to disperse the sample into separate particles, and the dispersed fire retardant powder particles are injected into the measuring pool of the laser particle size analyzer. The laser particle size analyzer receives the light scattered back from the fire retardant powder particles at multiple angles, shoots the images of the fire retardant powder particles under the irradiation of the laser beam at multiple angles, and configures a photodetector to record the initial light scattering intensity at different angles; therefore, the images of the fire retardant powder particles at different angles and the corresponding initial light scattering intensity are obtained. Among them, the initial light scattering intensity at each angle reflects the initial light scattering intensity of the fire retardant powder particles in the corresponding fire retardant powder particle image.

[0022] Step S2: For any angle, construct a sliding window to traverse the fire retardant powder particle image to obtain the particle connected domain and the light spot connected domain in each sliding window; for any sliding window, obtain the particle exposure degree of the sliding window according to the morphological characteristics of the particle connected domain in the sliding window; obtain the fire retardant powder dispersion degree of the sliding window according to the distribution of the particle connected domain in the sliding window and the particle exposure degree.

[0023] In order to efficiently process a large amount of image data, analyze the local features of the image more specifically, and understand and analyze the image content more accurately; for any angle, a sliding window is constructed to traverse the fire retardant powder particle image; it should be noted that, in one embodiment of the present invention, the sliding window starts to traverse from the upper left corner of the image, and the size is 30×30; in other embodiments of the present invention, the size of the sliding window can be set according to the specific situation, and is not limited or elaborated here.

[0024] When the laser beam irradiates the fire retardant powder particles, the different aggregation conditions between the particles produce an uneven irradiation effect that affects the formation and distribution of the light spot on the particle surface. Therefore, the particle connected domain and the light spot connected domain in each sliding window are obtained for analysis.

[0025] Preferably, in one embodiment of the present invention, the method for obtaining the particle connected domain and the light spot connected domain can be found in Figure 2 , which shows a flow chart of a method for acquiring a particle connected domain and a light spot connected domain, including: Step S201: using a connected domain detection algorithm to obtain multiple connected domains of each sliding window.

[0026] The connected domain detection algorithm can reduce the interference of noise on the analysis, and is helpful for subsequent separate processing and analysis of each region. It should be noted that the specific connected domain detection algorithm is a technical means well known to those skilled in the art, and will not be described in detail here.

[0027] Step S202: obtaining the average brightness value of all pixels in each connected domain as the local brightness level; obtaining the average local brightness level in all connected domains as the overall brightness level; obtaining the brightness fluctuation degree of the pixels in all connected domains as the brightness fluctuation value; obtaining the sum of the overall brightness level and the preset multiple of the brightness fluctuation value as the brightness reference value; Taking into account the characteristics that the brightness of the light spot is relatively large and the brightness of the particles themselves is relatively small, the brightness values ​​of the pixels in the connected domain are analyzed, and the overall brightness level and brightness fluctuation value are combined to ensure that the benchmark value takes into account both the average brightness and the range of brightness variation, which helps to more accurately identify light spots and particles.

[0028] It should be noted that, in one embodiment of the present invention, the degree of fluctuation can be expressed by calculating the standard deviation. The larger the standard deviation, the greater the degree of fluctuation, and the smaller the standard deviation, the smaller the degree of fluctuation. In other embodiments of the present invention, the degree of fluctuation can also be expressed by calculating the variance or range. The specific means are technical means well known to those skilled in the art and will not be elaborated here.

[0029] It should be noted that, in order to reflect the discreteness and stability of the brightness distribution, in one embodiment of the present invention, the preset multiple is 2; in other embodiments of the present invention, the preset multiple can be set according to specific circumstances, which will not be elaborated here.

[0030] Step S203: if the local brightness level of the connected domain is greater than or equal to the brightness reference value, the corresponding connected domain is used as the light spot connected domain, and other connected domains except the light spot connected domain are used as particle connected domains.

[0031] The larger the local brightness level, the larger the brightness value of each pixel in the connected domain, and the more it corresponds to the light spot connected domain.

[0032] The morphological characteristics of the connected domain of particles reflect the exposure degree and distribution of particles. The larger the morphological characteristics, the more characteristics of the particles in the area and the greater the exposure degree. The particle exposure degree of each sliding window is obtained based on the morphological characteristics of the connected domain of particles in each sliding window.

[0033] Preferably, in one embodiment of the present invention, a method for obtaining the particle exposure degree includes: Constructing a maximum circumscribed rectangle of each particle connected domain; obtaining a ratio between the number of pixels in each particle connected domain and the number of pixels in the maximum circumscribed rectangle as a first ratio; The accumulated value of the first ratio corresponding to all particle connected domains in each sliding window is obtained as the particle exposure degree.

[0034] In one embodiment of the present invention, the formula for the particle exposure degree is expressed as: ; in, Indicates The particle exposure degree of a sliding window; Indicates The first The number of pixels in the connected domain of each particle; Indicates The first The number of pixels in the largest circumscribed rectangle corresponding to a particle connected domain; Indicates The number of connected regions of particles in a sliding window.

[0035] In the formula of particle exposure, the more pixels there are in the particle connected domain, the more particle characteristics the area corresponding to the particle connected domain exhibits, and the more particles are exposed.

[0036] The distribution of particle connected domains and the degree of particle exposure reflect the dispersion of fire retardant powder particles in space. The more particle connected domains are distributed, the worse the dispersion of fire retardant powder particles in space is. The greater the particle exposure, that is, the greater the morphological characteristics of each particle connected domain, the more dispersed the fire retardant powder particles are distributed in space, and the smaller the overlapping area between particles. According to the distribution of particle connected domains in the sliding window and the degree of particle exposure, the dispersion degree of fire retardant powder in the sliding window is obtained.

[0037] Preferably, in one embodiment of the present invention, the method for obtaining the dispersion degree of the fire retardant powder includes: Obtain the ratio of the number of connected domains of particles to the number of pixels in each sliding window as the particle density of each sliding window; The ratio of the particle exposure degree to the particle density degree of each sliding window is obtained as the dispersion degree of the fire retardant powder in each sliding window.

[0038] In one embodiment of the present invention, the formula for the dispersion degree of the fire retardant powder is expressed as: ; ; in, Indicates The degree of dispersion of fire retardant powder in each sliding window; Indicates The particle exposure degree of a sliding window; Indicates The density of particles in a sliding window; Indicates The number of fire retardant powder particles per sliding window; Indicates The number of pixels in a sliding window.

[0039] In the formula for the dispersion degree of fire retardant powder, the more fire retardant powder particles there are in the sliding window, the denser the particles are, and the less dispersed the particles in the window are; the more exposed the particles are, the greater the dispersion degree is.

[0040] Step S3: in the connected domain of the light spot in the sliding window, obtain the pixel neighborhood window corresponding to each light spot edge pixel point; obtain the blur degree of the light spot edge of the corresponding sliding window according to the gradient characteristics of the light spot edge pixel points in different pixel neighborhood windows; obtain the brightness difference evaluation of the sliding window according to the brightness distribution of different light spot pixel points in the sliding window; obtain the illumination uniformity of the sliding window according to the dispersion degree of fire retardant powder, blur degree of light spot edge and brightness difference evaluation of the sliding window.

[0041] In order to avoid being affected by other interference noises, the image details are analyzed, and the pixel neighborhood window corresponding to each spot edge pixel point is obtained in the spot connected domain of the sliding window. It should be noted that in one embodiment of the present invention, in the spot connected domain of the sliding window, traversal is started from the upper left corner, with each spot edge pixel point as the center, and a 3×3 size range is formed with other pixel points as the pixel neighborhood window, wherein the pixel point corresponds to only one pixel neighborhood window, and the pixel neighborhood windows do not overlap each other; in other embodiments of the present invention, the size of the pixel neighborhood window can be set according to the specific situation, which is not limited or elaborated here.

[0042] The different degrees of dispersion of fire retardant powder in different windows make the manifestation of light spots different. By analyzing the gradient characteristics of the pixels at the edge of the light spots, the brightness changes of the pixels in the image are reflected, and the edge clarity is evaluated more intuitively. The larger the gradient value of the pixel, the clearer the edge, the stronger the contrast, and the smaller the blur of the light spot edge. On the contrary, the smaller the gradient value of the pixel, the softer the edge and the greater the blur of the light spot edge. According to the gradient characteristics of the pixels at the edge of the light spots in different pixel neighborhood windows, the blur degree of the light spot edge of the corresponding sliding window is obtained.

[0043] Preferably, in one embodiment of the present invention, the method for obtaining the blur degree of the light spot edge includes: Obtain the sum of the gradients of all the pixels at the edge of the light spot in each pixel neighborhood window as the local gradient level; The blur degree of the light spot edge of the sliding window is obtained according to the fluctuation degree of the local gradient level of different pixel neighborhood windows in the sliding window. The fluctuation degree of the local gradient level is negatively correlated with the blur degree of the light spot edge.

[0044] It should be noted that, in one embodiment of the present invention, the degree of fluctuation is expressed by calculating the variance. The larger the variance, the greater the degree of fluctuation, and the smaller the variance, the smaller the degree of fluctuation. In other embodiments of the present invention, the degree of fluctuation can also be expressed by calculating the standard deviation and the range. The specific means are technical means well known to those skilled in the art and will not be elaborated here.

[0045] Among them, the greater the fluctuation degree, the more inconsistent the local gradient level of the pixel neighborhood window is, showing a stronger contrast, and the smaller the blur of the spot edge is, showing a negative correlation.

[0046] In one embodiment of the present invention, the formula for the blur degree of the light spot edge is expressed as: ; in, Indicates The blur degree of the spot edge of the sliding window; Indicates The number of pixel neighborhood windows within a sliding window; Indicates The first The sum of the gradients of all the pixels at the edge of the light spot in the pixel neighborhood window is the local gradient level. Indicates The mean of the local gradient levels corresponding to all pixel neighborhood windows in a sliding window.

[0047] In the formula for the blur degree of the light spot edge, It indicates the variance of the local gradient level calculated for different pixel neighborhood windows, indicating the degree of fluctuation. The larger the variance, the more inconsistent the local gradient level, the greater the degree of fluctuation, the greater the contrast between the neighborhood windows, and the smaller the blur of the spot edge. In the denominator Add 0.01 to avoid the denominator being 0, which makes the formula meaningless.

[0048] The dispersion of the fire retardant powder can be reflected by analyzing the brightness distribution of different light spot pixels in the sliding window. The more uniform the overall brightness distribution, the smaller the difference between the center and the edge of the light spot, the more uniform the distribution of the fire retardant powder, and the smaller the brightness difference evaluation; the more uneven the overall brightness distribution, the greater the difference between the center and the edge of the light spot, the more uneven the distribution of the fire retardant powder, and the greater the brightness difference evaluation; according to the brightness distribution of different light spot pixels in the sliding window, the brightness difference evaluation of the sliding window is obtained.

[0049] Preferably, in one embodiment of the present invention, the method for obtaining the brightness-darkness difference evaluation includes: The difference between the maximum brightness and the minimum brightness of the light spot pixel in the sliding window is obtained as the brightness difference evaluation of the sliding window.

[0050] By evaluating and analyzing the dispersion degree of fire retardant powder, the blur degree of light spot edge and the difference between brightness and darkness, the uniformity of illumination of the sliding window can be evaluated more comprehensively and effectively; the better the dispersion degree of fire retardant powder, the more uniform the distribution of light spot on the sliding window, which makes the uniformity of illumination greater; the lower the blur degree of light spot edge, the more uniform the illumination distribution and the higher the uniformity of illumination; the smaller the difference between brightness and darkness, the more uniform the brightness distribution and the better the light transmittance of the window, which makes the uniformity of illumination higher; according to the evaluation of the dispersion degree of fire retardant powder, the blur degree of light spot edge and the difference between brightness and darkness of the sliding window, the uniformity of illumination of the sliding window can be obtained.

[0051] Preferably, in one embodiment of the present invention, the method for obtaining the illumination uniformity includes: A negative correlation mapping is performed on the brightness and darkness difference evaluation of the sliding window as the first uniformity coefficient; The first uniformity coefficient of the sliding window, the blurring degree of the light spot edge and the dispersion degree of the fire retardant powder are integrated to serve as the illumination uniformity of the sliding window.

[0052] It should be noted that, in some embodiments of the present invention, fusion can be performed by addition or multiplication. The specific means are technical means well known to those skilled in the art and will not be described in detail here.

[0053] In one embodiment of the present invention, the formula for the degree of illumination uniformity is expressed as: ; in, Indicates The uniformity of illumination of the sliding window; Indicates The degree of dispersion of fire retardant powder in each sliding window; Indicates The blur degree of the spot edge of the sliding window; Indicates Evaluation of the brightness and darkness difference of a sliding window.

[0054] In the formula for irradiation uniformity, middle The reason for adding 0.01 is to avoid the denominator being 0, which would make the formula meaningless. The first uniformity coefficient is obtained by negatively correlating the brightness and darkness difference evaluation of the sliding window. The larger the first uniformity coefficient, the greater the brightness and darkness difference evaluation, the greater the contrast difference, the more uneven the brightness of the light spot, and the smaller the illumination uniformity. The greater the dispersion of the fire retardant powder in a sliding window, the greater the blurriness of the edge of the light spot, the light spot presents a relatively uniform brightness distribution, and the greater the illumination uniformity.

[0055] It should be noted that in other embodiments of the present invention, Function to Negative correlation mapping is performed to construct a correlation relationship in which the greater the brightness difference evaluation, the smaller the illumination uniformity. The specific means are well known to those skilled in the art and will not be described in detail here.

[0056] Step S4: According to the initial light scattering intensity corresponding to each sliding window at different angles and the irradiation uniformity, the corrected light scattering intensity of each sliding window at each angle is obtained, and the overall light scattering intensity of each fire retardant powder particle is obtained.

[0057] The initial light scattering intensity is the intensity of scattered light after the interaction between light and matter, reflecting the scattering ability of fire retardant powder particles to light. The uniformity of illumination is an important factor affecting the accuracy of light scattering measurement. If the illumination is uneven, even the same fire retardant powder particles may produce different light scattering intensities at different positions. By considering the uniformity of illumination, the initial light scattering intensity can be corrected as necessary, thereby more accurately reflecting the true scattering characteristics of the material at different angles. According to the initial light scattering intensity corresponding to each sliding window at different angles and the uniformity of illumination, the corrected light scattering intensity of each sliding window at each angle is obtained.

[0058] Preferably, in one embodiment of the present invention, the method for obtaining the corrected light scattering intensity is as follows: Figure 3 , which shows a flow chart of a method for obtaining a corrected light scattering intensity, comprising: Step S301: According to the illumination uniformity corresponding to the sliding window at different angles, a normal illumination window and an abnormal illumination window at each angle are screened out.

[0059] The uniformity of the illumination of the sliding window reflects the uniformity of the laser beam distribution in the sliding window. The greater the illumination uniformity, the greater the uniformity of the laser beam distribution, and the smaller the illumination uniformity, the smaller the uniformity of the laser beam distribution. Normal illumination windows and abnormal illumination windows at each angle are screened out.

[0060] Preferably, in one embodiment of the present invention, screening out the normal illumination window and the abnormal illumination window at each angle includes: For any angle, if the illumination uniformity of the sliding window is less than the preset uniformity threshold, the corresponding sliding window is regarded as an abnormal illumination window; if the illumination uniformity of the sliding window is greater than or equal to the preset uniformity threshold, the corresponding sliding window is regarded as a normal illumination window.

[0061] It should be noted that, in one embodiment of the present invention, the size of the preset uniform threshold is 0.5; in other embodiments of the present invention, the size of the preset uniform threshold can be specifically set according to specific circumstances, which is not limited or elaborated herein.

[0062] Step S302: For any angle, if the sliding window is an abnormal illumination window, obtain the normal illumination window corresponding to the abnormal illumination window at other angles as the target window; obtain the mean of the illumination uniformity of all target windows as the first mean; obtain the mean of the initial light scattering intensity of all target windows at the corresponding angles as the second mean; obtain the ratio of the first mean to the illumination uniformity of the abnormal illumination window at the corresponding angle, and calculate the product between the ratio result and the second mean as the corrected intensity weight.

[0063] Since the abnormal illumination window may be caused by special conditions at a specific angle, the initial light scattering intensity of the abnormal illumination window at the corresponding angle is corrected by selecting the normal illumination window corresponding to other angles; The first mean is used to evaluate the general illumination uniformity of the normal illumination window and to measure the light scattering quality when there is no abnormal condition. The difference between the abnormal illumination window and the normal state can be reflected by calculating the ratio of the first mean and the illumination uniformity of the abnormal illumination window at the corresponding angle. The greater the difference, the greater the illumination uniformity of the abnormal illumination window, that is, the greater the ratio, the greater the degree of correction required. The smaller the difference, the greater the illumination uniformity of the abnormal illumination window and the closer it is to the normal state, that is, the smaller the ratio, the smaller the degree of correction required. The second mean is used to evaluate the general light scattering intensity of the normal illumination window. The greater the light scattering intensity of the normal illumination window, the more correction is needed towards the larger trend.

[0064] Step S303: obtaining the sum of the initial light scattering intensity and the corrected intensity weight at the corresponding angle of each abnormal illumination window as the corrected light scattering intensity of each abnormal illumination window at the corresponding angle.

[0065] In one embodiment of the present invention, for the abnormal illumination window, the formula for correcting the light scattering intensity is expressed as: ; in, Indicates Angle Corrected light scattering intensity of an abnormal illumination window; Indicates The average value of the initial light scattering intensity at the angle of the target window corresponding to the abnormal illumination window is the second average value; Indicates The average of the illumination uniformity of the target window corresponding to the abnormal illumination window is the first average; Indicates Angle The illumination uniformity of an abnormal illumination window.

[0066] In the formula for correcting the light scattering intensity, the fire retardant powder in the abnormal irradiation window is poorly dispersed. Due to the dense aggregation of particles, it cannot fully receive the laser beam. The light scattering intensity is relatively small when it is relatively evenly distributed, and there is a large deviation. Indicates calculation of the first mean and the Angle The larger the ratio, the larger the first mean, that is, the larger the illumination uniformity of the corresponding target window. It represents the product of the calculated ratio and the second mean, that is, the corrected intensity weight. The larger the corrected intensity weight, the larger the second mean, the greater the illumination uniformity of the corresponding target window, the greater the initial light scattering intensity, and the greater the correction of the initial light scattering intensity of the abnormal illumination window; the greater the initial light scattering intensity of the abnormal illumination window, the greater the corrected light scattering intensity.

[0067] Step S304: If the sliding window is a normal illumination window, the initial light scattering intensity at the corresponding angle of the sliding window is used as the corrected light scattering intensity.

[0068] Since a fire retardant powder particle may appear in images at multiple angles, the corrected light scattering intensity of the sliding window at different angles is integrated into a comprehensive index to facilitate the subsequent overall evaluation of the properties of the fire retardant powder particles. It reflects the overall scattering ability of the particles to light and is an important indicator for evaluating the properties of the particles. The overall light scattering intensity of each fire retardant powder particle is obtained.

[0069] Preferably, in one embodiment of the present invention, the method for obtaining the overall light scattering intensity includes: Obtaining a ratio of the corrected light scattering intensity to the initial light scattering intensity of each sliding window at each angle as an intensity ratio; Calculate the product of the initial light scattering intensity of the sliding window at the corresponding angle of each fire retardant powder particle and the intensity ratio as the local light scattering intensity of the sliding window at the corresponding angle of each fire retardant powder particle; The corrected light scattering intensity of the sliding window of the same fire retardant powder particle at different angles is averaged to be the overall light scattering intensity of each fire retardant powder particle.

[0070] In one embodiment of the present invention, the overall light scattering intensity is expressed as: ; in, Fire retardant powder particles The overall light scattering intensity of Fire retardant powder particles Corresponding to Slide the window at an angle The initial light scattering intensity of Fire retardant powder particles Corresponding to Slide the window at an angle Corrected light scattering intensity; Fire retardant powder particles The number of corresponding angles.

[0071] In the formula for overall light scattering intensity, It means calculating the ratio of the corrected light scattering intensity to the initial light scattering intensity of each sliding window at each angle. As the intensity ratio, the larger the corrected light scattering intensity, the greater the degree of correction. The larger the intensity ratio, the greater the correction of the light scattering intensity of the fire retardant powder particles.

[0072] Step S5: performing a particle size distribution test on the mineral fire retardant powder particles according to the overall light scattering intensity.

[0073] By obtaining the overall light scattering intensity of each fire retardant powder particle, the scattering characteristics of the particles are more accurately reflected, which is conducive to the subsequent laser particle size analysis method to accurately test the particle size distribution of the fire retardant powder particles and more accurately evaluate the performance of the fire retardant powder. The particle size distribution of the mineral fire retardant powder particles is tested according to the overall light scattering intensity. The specific laser particle size analysis method is a technical means well known to those skilled in the art and will not be described in detail here.

[0074] In summary, the present invention obtains the degree of dispersion of fire retardant powder in the sliding window according to the morphological characteristics of the connected domain of particles in the sliding window; obtains the pixel neighborhood window corresponding to each pixel point of the edge of the light spot in the connected domain of the light spot in the sliding window; obtains the blurring degree of the light spot edge of the corresponding sliding window according to the gradient characteristics of the pixel points of the light spot edge in different pixel neighborhood windows; obtains the brightness difference evaluation of the sliding window according to the brightness distribution of different light spot pixels in the sliding window; obtains the uniformity of illumination of the sliding window, combines the initial light scattering intensity corresponding to each sliding window at different angles, obtains the corrected light scattering intensity of each sliding window at each angle, and obtains the overall light scattering intensity of each fire retardant powder particle; and performs a particle size distribution test on the fire retardant powder particles. The present invention improves the accuracy of particle size distribution by obtaining the accurate light scattering intensity of each fire retardant powder particle.

[0075] It should be noted that the sequence of the above embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0076] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

Claims

1. A method for testing particle size distribution of mineral fire retardant powder, characterized in that: The method comprises: Obtaining images of fire retardant powder particles at different angles and the corresponding initial light scattering intensity; For any angle, a sliding window is constructed to traverse the image of the fire retardant powder particles, and the particle connected domain and the light spot connected domain in each sliding window are obtained; for any sliding window, the particle exposure degree of the sliding window is obtained according to the morphological characteristics of the particle connected domain in the sliding window; the fire retardant powder dispersion degree of the sliding window is obtained according to the distribution of the particle connected domain in the sliding window and the particle exposure degree; In the light spot connected domain of the sliding window, the pixel neighborhood window corresponding to each light spot edge pixel point is obtained; the blur degree of the light spot edge of the corresponding sliding window is obtained according to the gradient characteristics of the light spot edge pixel points in different pixel neighborhood windows; the brightness difference evaluation of the sliding window is obtained according to the brightness distribution of different light spot pixel points in the sliding window; the illumination uniformity of the sliding window is obtained according to the dispersion degree of fire retardant powder, blur degree of light spot edge and brightness difference evaluation of the sliding window; According to the initial light scattering intensity corresponding to each sliding window at different angles and the irradiation uniformity, the corrected light scattering intensity of each sliding window at each angle is obtained, and the overall light scattering intensity of each fire retardant powder particle is obtained; The particle size distribution of the fire retardant powder particles is tested according to the overall light scattering intensity.

2. A method for testing particle size distribution of mineral fire retardant powder according to claim 1, characterized in that: The method for acquiring the particle connected domain and the light spot connected domain comprises: A connected domain detection algorithm is used to obtain multiple connected domains of each sliding window; Obtain the average brightness value of all pixels in each connected domain as the local brightness level; obtain the average local brightness level in all connected domains as the overall brightness level; obtain the brightness fluctuation degree of the pixels in all connected domains as the brightness fluctuation value; obtain the sum of the overall brightness level and the preset multiple of the brightness fluctuation value as the brightness reference value; If the local brightness level of the connected domain is greater than or equal to the brightness reference value, the corresponding connected domain is regarded as the light spot connected domain, and the other connected domains except the light spot connected domain are regarded as particle connected domains.

3. A method for testing particle size distribution of mineral fire retardant powder according to claim 1, characterized in that: The method for obtaining the particle exposure degree includes: Construct the maximum enclosing rectangle of each particle connected domain; Obtaining a ratio of the number of pixels in each particle connected domain to the number of pixels in the maximum circumscribed rectangle as a first ratio; The accumulated value of the first ratio corresponding to all particle connected domains in each sliding window is obtained as the particle exposure degree.

4. A method for testing particle size distribution of mineral fire retardant powder according to claim 1, characterized in that: The method for obtaining the dispersion degree of the fire retardant powder comprises: Obtain the ratio of the number of connected domains of particles to the number of pixels in each sliding window as the particle density of each sliding window; The ratio of the particle exposure degree to the particle density degree of each sliding window is obtained as the dispersion degree of the fire retardant powder in each sliding window.

5. A method for testing particle size distribution of mineral fire retardant powder according to claim 1, characterized in that: The method for obtaining the blur degree of the light spot edge includes: Obtain the sum of the gradients of all the pixel points at the edge of the light spot in each pixel neighborhood window as the local gradient level; The blur degree of the light spot edge of the sliding window is obtained according to the fluctuation degree of the local gradient level of different pixel neighborhood windows in the sliding window. The fluctuation degree of the local gradient level is negatively correlated with the blur degree of the light spot edge.

6. A method for testing particle size distribution of mineral fire retardant powder according to claim 1, characterized in that: The method for obtaining the brightness-darkness difference evaluation comprises: The difference between the maximum brightness and the minimum brightness of the light spot pixel in the sliding window is obtained as the brightness difference evaluation of the sliding window.

7. A method for testing particle size distribution of mineral fire retardant powder according to claim 1, characterized in that: The method for obtaining the irradiation uniformity comprises: A negative correlation mapping is performed on the brightness and darkness difference evaluation of the sliding window as the first uniformity coefficient; The first uniformity coefficient of the sliding window, the blurring degree of the light spot edge and the dispersion degree of the fire retardant powder are integrated to serve as the illumination uniformity of the sliding window.

8. A method for testing particle size distribution of mineral fire retardant powder according to claim 1, characterized in that: The method for obtaining the corrected light scattering intensity comprises: According to the illumination uniformity of the sliding window at different angles, the normal illumination window and the abnormal illumination window at each angle are screened out; For any angle, if the sliding window is an abnormal illumination window, obtain the normal illumination window corresponding to the abnormal illumination window at other angles as the target window; obtain the mean of the illumination uniformity of all target windows as the first mean; obtain the mean of the initial light scattering intensity of all target windows at the corresponding angles as the second mean; obtain the ratio of the first mean to the illumination uniformity of the abnormal illumination window at the corresponding angle, and calculate the product between the ratio result and the second mean as the corrected intensity weight; Obtaining the sum of the initial light scattering intensity and the corrected intensity weight at the corresponding angle of each abnormal illumination window as the corrected light scattering intensity of each abnormal illumination window at the corresponding angle; If the sliding window is a normal illumination window, the initial light scattering intensity at the corresponding angle of the sliding window is used as the corrected light scattering intensity.

9. A method for testing particle size distribution of mineral fire retardant powder according to claim 8, characterized in that: The screening out of the normal illumination window and the abnormal illumination window at each angle includes: For any angle, if the illumination uniformity of the sliding window is less than the preset uniformity threshold, the corresponding sliding window is regarded as an abnormal illumination window; if the illumination uniformity of the sliding window is greater than or equal to the preset uniformity threshold, the corresponding sliding window is regarded as a normal illumination window.

10. A method for testing particle size distribution of mineral fire retardant powder according to claim 1, characterized in that: The method for obtaining the overall light scattering intensity comprises: Obtaining a ratio of the corrected light scattering intensity to the initial light scattering intensity of each sliding window at each angle as an intensity ratio; Calculate the product of the initial light scattering intensity of the sliding window at the corresponding angle of each fire retardant powder particle and the intensity ratio as the local light scattering intensity of the sliding window at the corresponding angle of each fire retardant powder particle; The corrected light scattering intensity of the sliding window of the same fire retardant powder particle at different angles is averaged to be the overall light scattering intensity of each fire retardant powder particle.

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