CN116148142A - Method, system and device for monitoring particle size and dynamic change of indoor air particulate matters - Google Patents
Method, system and device for monitoring particle size and dynamic change of indoor air particulate matters Download PDFInfo
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Abstract
The invention discloses a method, a system and a device for monitoring particle size and dynamic change of particle size of indoor air particles, wherein the method comprises the following steps: acquiring a plurality of laser images of an indoor target area; extracting the gray value of each pixel point for each laser beam of each laser image and determining a scattering angle; for each pixel point, the gray value and the scattering angle corresponding to the same pixel point in a plurality of laser images are brought into a relation between the gray value and the particle size characteristic value to obtain the particle size characteristic value of the air particles at each pixel point, the particle size distribution at each pixel point is determined by combining the relation between the particle size characteristic and the particle size distribution, and then the particle size distribution space information of the indoor air particles is determined; and determining the particle size dynamic change of the indoor air particles according to the particle size distribution of each pixel point corresponding to different moments, and describing the particle size information of the particles and the change process of the particle size information.
Description
Technical Field
The invention relates to the technical field of particle size monitoring, in particular to an on-line monitoring method, system and device for particle size and dynamic change of particle size of indoor air particles.
Background
Particulate matter in indoor air and health hazards thereof: the particulate matter in air consists of very small particles and droplets. PM2.5 and PM10, as commonly discussed, refer to particulate matter having aerodynamic particle sizes less than 2.5 microns and 10 microns, respectively. The PM2.5 can directly permeate into bronchioles and lungs due to extremely small particle size, and causes great harm to human health. Thus, prolonged exposure of PM2.5 will increase morbidity and mortality in humans. Recent studies have demonstrated that submicron particles, i.e. PM1.0 with an aerodynamic particle size of less than 1.0 micron, and ultra-fine particles (ultrafine particles, UFP), i.e. particles with a particle size of less than 100 nm, are more health-critical. The time that most people stay indoors (average over 22 hours) is much higher than the time that people stay outdoors, and thus the importance of the exposure of particulate matter in indoor air to the population is much higher than outdoors.
Particle size distribution refers to the relationship between the concentration of particles (or aerosols) and the particle size, and is an important physical parameter, closely related to the source and formation process. The particle size of the particulate matter may be expressed as aerodynamic diameter.
Determination of particle size distribution of air particles:
in addition to off-line analysis techniques employing cascade impact sampler sampling and weighing, atmospheric aerosol particle size resolution includes electrostatic classification and light scattering. For example, an aerosol particle size spectrometer adopts a uniform xenon lamp white light source according to the light scattering principle, and utilizes a 90-degree scattering angle to detect and measure the aerosol particle size in the air on line. Typical devices can range from 0.2 to 105 μm. Currently, all on-line measurement techniques can only measure the particle size of particulate matter at one point in space.
The vertical section measurement technology of outdoor and indoor particulate matters comprises the following steps:
the backscattering lidar technique is the main method for determining the vertical profile of the concentration of outdoor particulate matter. The traditional back scattering laser radar has a section of blind area near the receiving end and a longer transition area, and the transition area can carry out geometric factor correction, but can bring a large error. In recent years, students improve the traditional laser radar, and research the side scattering laser radar, so that the defects of the traditional laser radar can be overcome to a great extent. Indoor side-scatter Lidar (I-Lidar) technology developed with reference to outdoor side-scatter Lidar technology provides a means to continuously monitor dynamic changes in indoor air particulate matter profile concentration, providing an important tool for studying indoor particulate matter sources and exposure. However, the indoor laser radar technology can measure the concentration profile of indoor air particles, but lacks the depiction and description of the particle size information and the change process of the particles.
Disclosure of Invention
The invention aims to provide a method, a system and a device for monitoring particle size and dynamic change of indoor air particles, which can accurately monitor particle size and particle size dynamic change process of the indoor air on line based on the principle of multi-angle light scattering difference of the particles with different particle sizes, and realize the description and the description of particle size information and the change process of the particles.
In order to achieve the above object, the present invention provides the following solutions:
a method for monitoring particle size and dynamic change of particle size of indoor air particles, comprising:
acquiring a plurality of laser images of an indoor target area; each laser image comprises a plurality of laser beams; the laser images are obtained by shooting a plurality of CCD cameras distributed on the side surfaces of the laser beams in a one-to-one correspondence manner; the plurality of laser images are images of the same position of the laser beam, which are respectively shot by the CCD cameras from different angles;
extracting a gray value of each pixel point in each laser beam for each laser beam of each laser image, and determining a scattering angle at each pixel point;
for each pixel point, bringing the gray value and the scattering angle corresponding to the same pixel point in a plurality of laser images into a relation between the gray value and the particle size characteristic value to obtain the particle size characteristic value of air particles at each pixel point;
for each pixel point, determining the particle size distribution at each pixel point according to the particle size characteristic value and the relation between the particle size characteristic and the particle size distribution; the relation between the particle size characteristics and the particle size distribution is predetermined through experiments; the particle size distribution comprises particle size information of indoor air particles;
determining the particle size distribution space information of indoor air particles according to the particle size distribution at each pixel point;
and determining the dynamic change of the particle size of the indoor air particles according to the particle size distribution at each pixel point corresponding to different moments.
Optionally, the relation between the gray value and the particle size characteristic value is:
wherein g is a particle size characteristic value, θ is a scattering angle, I is an extracted gray value, and p 1 ，p 2 Is a coefficient.
Optionally, for each pixel, the step of bringing the gray value and the scattering angle corresponding to the same pixel in the plurality of laser images into a relation between the gray value and the particle size characteristic value to obtain the particle size characteristic value of the air particulate matter at each pixel specifically includes:
taking the gray value and the scattering angle corresponding to the same pixel point in a plurality of laser images as a data set;
for each data set, respectively bringing the gray value and the scattering angle in the data set into the relation between the gray value and the particle size characteristic value to obtain an equation set to be solved; the equation set to be solved comprises a plurality of equations to be solved;
for the coefficient p in the equation to be solved 1 Sum coefficient p 2 And solving the particle size characteristic value g to obtain the particle size characteristic value g corresponding to each data set, namely the particle size characteristic value of the air particulate matters at each pixel point.
Optionally, the determining the spatial information of the particle size distribution of the indoor air particulate matter according to the particle size distribution at each pixel point specifically includes:
and according to the particle size distribution of all the pixel points of each laser beam in the laser image, performing linear interpolation on gaps among different laser beams to obtain the space information of the particle size distribution.
The invention also provides a system for monitoring the particle size and the dynamic change of the particle size of the indoor air particles, which comprises:
the image acquisition module is used for acquiring a plurality of laser images of the indoor target area; each laser image comprises a plurality of laser beams; the laser images are obtained by shooting a plurality of CCD cameras distributed on the side surfaces of the laser beams in a one-to-one correspondence manner; the plurality of laser images are images of the same position of the laser beam, which are respectively shot by the CCD cameras from different angles;
the gray scale and scattering angle acquisition module is used for extracting the gray scale value of each pixel point in each laser beam for each laser beam of each laser image and determining the scattering angle at each pixel point;
the particle size characteristic value acquisition module is used for bringing the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images into a relation between the gray value and the particle size characteristic value to obtain the particle size characteristic value of the air particulate matters at each pixel point;
the particle size distribution acquisition module is used for determining the particle size distribution of each pixel point according to the particle size characteristic value and the relation between the particle size characteristic and the particle size distribution; the relation between the particle size characteristics and the particle size distribution is predetermined through experiments; the particle size distribution comprises particle size information of indoor air particles;
the particle size distribution space information acquisition module is used for determining the particle size distribution space information of indoor air particles according to the particle size distribution at each pixel point;
and the particle size dynamic change observation module is used for determining the particle size dynamic change of the indoor air particulate matters according to the particle size distribution at each pixel point corresponding to different moments.
Optionally, the relation between the gray value and the particle size characteristic value is:
wherein g is a particle size characteristic value, θ is a scattering angle, I is an extracted gray value, and p 1 P2 is a coefficient.
Optionally, the particle size characteristic value obtaining module specifically includes:
the data set construction unit is used for taking the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images as one data set;
the equation solving unit is used for respectively bringing the gray value and the scattering angle in each data set into the relation between the gray value and the particle size characteristic value to obtain an equation set to be solved; the equation set to be solved comprises a plurality of equations to be solved;
a particle size characteristic value determining unit for determining the coefficient p in the equation to be solved 1 Sum coefficient p 2 And solving the particle size characteristic value g to obtain the particle size characteristic value g corresponding to each data set, namely the particle size characteristic value of the air particulate matters at each pixel point.
Optionally, the particle size distribution spatial information acquisition module specifically includes:
and according to the particle size distribution of all the pixel points of each laser beam in the laser image, performing linear interpolation on gaps among different laser beams to obtain the space information of the particle size distribution.
The invention also provides an indoor air particulate matter particle size and particle size dynamic change monitoring device, which comprises a laser, a plurality of CCD cameras and a processor;
the laser is used for emitting laser beams to indoor air;
the CCD cameras are arranged on the side surfaces of the laser beams and are used for shooting laser images of the same position of the laser beams from different angles;
the processor being configured to perform the method of any one of claims 1 to 4.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a method, a system and a device for monitoring particle size and particle size dynamic change of indoor air particles, which are characterized in that the particle size distribution at each pixel point is determined according to the scattered light intensity difference (gray value difference) of each pixel point in laser images at different angles by acquiring the laser images of the same position of laser beams shot by CCD cameras at different angles, so that the spatial information of the particle size distribution of the indoor air particles and the particle size dynamic change condition are determined, and the description of the particle size information of the particles and the change process of the particle size information are realized.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for monitoring particle size and dynamic change of particle size of indoor air particles according to embodiment 1 of the present invention;
fig. 2 is a schematic diagram of the positional relationship between the laser and the CCD camera provided in embodiment 1 of the present invention;
fig. 3 is a schematic diagram showing the difference between signals obtained by shooting the same position with different angle CCD cameras according to embodiment 1 of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a method, a system and a device for monitoring particle size and particle size dynamic change of indoor air particles, which are used for determining particle size distribution at each pixel point according to scattered light intensity differences (gray value differences) of each pixel point in laser images at different angles by acquiring laser images of the same position of laser beams shot by a CCD camera at different angles, further determining spatial information of particle size distribution of the indoor air particles and particle size dynamic change conditions, and realizing the description and description of particle size information of the particles and change processes of the particle size information.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1
As shown in fig. 1, the embodiment provides a method for monitoring particle size and dynamic change of particle size of indoor air particles, which includes:
s1: acquiring a plurality of laser images of an indoor target area; each laser image comprises a plurality of laser beams; the laser images are obtained by shooting a plurality of CCD cameras distributed on the side surfaces of the laser beams in a one-to-one correspondence manner; the plurality of laser images are images of the same position of the laser beam, which are respectively shot by the plurality of CCD cameras from different angles. As shown in fig. 2, a laser beam is emitted by a laser, and a CCD camera is used to collect scattering signals of air particles in different directions from the side, and fig. 2 shows the relative positional relationship between the laser and the CCD camera. The laser beam direction can be adjusted arbitrarily according to the section direction to be observed, and a plurality of lasers can be arranged to acquire two-dimensional or multidimensional dynamic information.
S2: for each laser beam of each laser image, extracting a gray value of each pixel point in the laser beam, and determining a scattering angle at each pixel point. The scatter angle is calculated in combination with the position of the camera.
S3: and for each pixel point, bringing the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images into a relation between the gray value and the particle size characteristic value to obtain the particle size characteristic value of the air particulate matters at each pixel point.
The gray value of the photo shot by the CCD camera is in direct proportion to the received light energy, and the scattering of the laser beams by different particle sizes causes the difference of the light energy received by the CCD, so that the gray value of the same point of the photo shot by different cameras can be extracted through software, and as shown in fig. 3, the information of the particle size distribution is calculated according to the camera position, the gray value difference and an empirical fitting formula (the relation between the gray value and the particle size characteristic value).
The relation between the gray value and the particle size characteristic value is as follows:
wherein g is a particle size characteristic value, θ is a scattering angle, I is an extracted gray value, and p 1 ，p 2 Is a coefficient. The g value is a value related to the particle size and refractive index of the particulate matters, g values of different particle sizes are different, g values of mixed particle sizes can be regarded as linear combination of g values of different particle sizes, and the relation between the g values and the particle size distribution is constructed through a pre-experiment according to the g values.
The derivation process of the relation between the gray value and the particle size characteristic value is as follows:
when the ratio of the particle size to the laser wavelength is greater than 0.1, the scattering can be explained by Mie scattering theory. For aerosols of a general particle size in air, the scattering when irradiated by 532nm laser light is within this range (particles having a particle size to 532nm wavelength ratio of greater than one), which corresponds to the Mie scattering theory. The scattered light intensity is related to camera shooting angle and can be expressed by a heney-Greenstein phase function:
wherein θ is the angle between the incident direction and the scattering direction, g is the relative intensity of front and back scattering, namely the particle size characteristic value named in the invention, and is related to the particle size and refractive index of the particles. And obtaining I and theta according to experiments, and further obtaining g values. Phg (θ, g) represents the probability of the distribution of the scattered light energy at an angle θ to the incident light. The g values of the particles of different particle sizes are different, and thus the phase functions p (θ) (i.e., phg (θ, g)) of different particle sizes are also different. This relationship provides a theoretical basis and possibility for detecting particle size of the particulate matter.
The principle of detecting the concentration of the indoor side scattering laser radar (I-Lidar) is as follows:
where E (θ) is the energy of side scattered light received by the CCD camera at a scattering angle θ, which is proportional to the gray value I, and may be represented by γi, and p (θ) is an aerosol scattering phase function. The other variables are known constants, K is a system constant, E l For the total laser energy emitted by the laser emitter during the exposure time S p For the receiving area of each picture element beta s For the average value of the angular scattering cross section, ρ is the aerosol particle density, c is the proportionality coefficient of PM2.5 particles per unit mass, and α is PM 2.5 Particle size, M is PM 2.5 Concentration, N atm Number of molecules per unit volume, beta atm Is the molecular angle scattering coefficient. d is the differential sign of the angle.
And (3) replacing E (theta) by gamma I, expressing a phase function p (theta) by a Henyey-Greenstein phase function, dividing both sides of a Phg (theta, g) equation and an E (theta) equation by gamma, and combining all coefficients to obtain a relation between a gray value and a g value.
Based on the deduced relation between the gray value and the particle size characteristic value, the step S3 specifically includes:
s31: and taking the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images as a data set.
S32: for each data set, respectively bringing the gray value and the scattering angle in the data set into the relation between the gray value and the particle size characteristic value to obtain an equation set to be solved; the system of equations to be solved includes a plurality of equations to be solved.
S33: for a pair ofThe coefficient p in the equation to be solved 1 Sum coefficient p 2 And solving the particle size characteristic value g to obtain the particle size characteristic value g corresponding to each data set, namely the particle size characteristic value of the air particulate matters at each pixel point.
And if a plurality of equations to be solved exist, a plurality of equations to be solved are needed, so that the number of the obtained laser images is more than or equal to the number of the equations to be solved. The number of the equations to be solved is the same as the number of the laser images, or the number of the equations to be solved is larger than the number of the laser images.
S4: for each pixel point, determining the particle size distribution at each pixel point according to the particle size characteristic value and the relation between the particle size characteristic and the particle size distribution; the relation between the particle size characteristics and the particle size distribution is predetermined through experiments; the particle size distribution includes indoor air particulate size information.
The relation between the particle size characteristics and the particle size distribution is predetermined through experiments, specifically, a series of pre-experiments are performed in a laboratory, a particle generator is used for sequentially generating a plurality of particles with known particle sizes, a scene with relatively uniform concentration and particle size is constructed, the particle sizes and the concentrations of the particles are known in the scene, a laser beam is emitted by a laser in the scene, a laser image is shot by a CCD camera, and then a particle size characteristic value g is obtained according to steps S1 to S3. By setting various scenes, the relation between the particle size characteristic value g and the particle size distribution can be obtained.
When in actual monitoring, after calculating a particle size characteristic value g in step S3, the particle size distribution corresponding to the value g can be determined according to the relationship between g and the particle size distribution. The particle size distribution is known, so that the concentration of the particles and the particle size information can be synchronously obtained.
S5: and determining the particle size distribution space information of the indoor air particles according to the particle size distribution at each pixel point.
And obtaining the particle size distribution condition of each point of each laser beam in the photo, and performing simple linear interpolation calculation between different laser beams to obtain the spatial information of the particle size distribution.
Specifically, step S5 includes:
and according to the particle size distribution of all the pixel points of each laser beam in the laser image, performing linear interpolation on gaps among different laser beams to obtain the space information of the particle size distribution.
S6: and determining the dynamic change of the particle size of the indoor air particles according to the particle size distribution at each pixel point corresponding to different moments.
And processing each frame shot by the CCD camera, so that the dynamic multidimensional monitoring of the particle size distribution can be performed.
1 System check-Pre-experiment construction (g value vs. particle size)
1-1 a green laser with a wavelength of 532nm was placed in the laboratory cabin, emitting a vertical laser beam from bottom to top. 3-4 CCD cameras (external 532nm filters) are arranged at different heights on the side surface. And sequentially generating a plurality of particles with known particle sizes by using a particle generator, constructing a scene with relatively uniform concentration and particle size, and measuring the particle sizes of the particles by using a particle size spectrometer. Side scatter information was obtained in each set of experiments. Establishing a relation between gray scale and particle size distribution according to data obtained from different angles of a plurality of groups of experiments; and simultaneously acquiring the concentration data of the particulate matters.
1-2, because physical and chemical properties of particles generated by a particle generator and environmental atmospheric particles possibly have differences, scattering signals can be influenced, the actual environmental air is introduced into an experiment cabin on the basis of 1-1 (a heavy pollution scene has higher signal than that of the particles, so that the effect of the experiment scene is more obvious), a scene with relatively uniform concentration and particle size is constructed, the concentration and particle size of the particles are measured in the same way (parameters are acquired by 1-1), and the accuracy of parameter values of 1-1 is verified by comparing the measurement results of a particle size spectrometer;
2 actual measurement check-measurement experiment
2-1, constructing a scene with uneven concentration and particle size by adopting a plurality of artificial emission sources, and measuring the concentration and the particle size of the particles by using the same equipment to obtain the spatial distribution and dynamic change characteristics of the concentration and the particle size;
2-2 verifying the non-vertical profile test effect in the same way by adopting the non-vertical laser system effect;
2-3, generating parallel vertical laser by adopting a row of multiple lasers, synchronously collecting scattering signals in the vertical direction of a laser plane by using a camera, and obtaining the two-dimensional particle size value (and concentration value) of the laser plane by mathematical interpolation;
2-4, adopting a plurality of lasers to form a laser matrix, synchronously collecting scattering signals by a camera, obtaining the concentration and particle size information of particles in the laser matrix, and obtaining the particle size value (and concentration value) of the particles in the three-dimensional space by mathematical interpolation.
In this embodiment, the gray value of the photo shot by the CCD camera is proportional to the received light energy, and the scattering of the laser beam by different particle sizes causes the difference in the light energy received by the CCD, so that the gray value of the same point of the photo shot by different cameras can be extracted by software, and the information of the particle size distribution is calculated according to the camera position, the gray value difference and the empirical fit formula, so that the description and the description of the particle size information of the particulate matter and the variation process thereof can be realized.
Example 2
The embodiment provides an indoor air particulate matter particle diameter and particle diameter dynamic change monitoring system, the system includes:
the image acquisition module is used for acquiring a plurality of laser images of the indoor target area; each laser image comprises a plurality of laser beams; the laser images are obtained by shooting a plurality of CCD cameras distributed on the side surfaces of the laser beams in a one-to-one correspondence manner; the plurality of laser images are images of the same position of the laser beam, which are respectively shot by the plurality of CCD cameras from different angles.
And the gray scale and scattering angle acquisition module is used for extracting the gray scale value of each pixel point in each laser beam for each laser beam of each laser image and determining the scattering angle at each pixel point.
The particle size characteristic value acquisition module is used for bringing the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images into a relation between the gray value and the particle size characteristic value for each pixel point to obtain the particle size characteristic value of the air particulate matters at each pixel point.
The relation between the gray value and the particle size characteristic value is as follows:
wherein g is a particle size characteristic value, θ is a scattering angle, I is an extracted gray value, and p 1 ，p 2 Is a coefficient.
The particle size characteristic value acquisition module specifically comprises:
and the data set construction unit is used for taking the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images as one data set.
The equation solving unit is used for respectively bringing the gray value and the scattering angle in each data set into the relation between the gray value and the particle size characteristic value to obtain an equation set to be solved; the system of equations to be solved includes a plurality of equations to be solved.
A particle size characteristic value determining unit for determining the coefficient p in the equation to be solved 1 Sum coefficient p 2 And solving the particle size characteristic value g to obtain the particle size characteristic value g corresponding to each data set, namely the particle size characteristic value of the air particulate matters at each pixel point.
The particle size distribution acquisition module is used for determining the particle size distribution of each pixel point according to the particle size characteristic value and the relation between the particle size characteristic and the particle size distribution; the relation between the particle size characteristics and the particle size distribution is predetermined through experiments; the particle size distribution includes indoor air particulate size information.
And the particle size distribution space information acquisition module is used for determining the particle size distribution space information of the indoor air particulate matters according to the particle size distribution at each pixel point. The method specifically comprises the following steps:
and according to the particle size distribution of all the pixel points of each laser beam in the laser image, performing linear interpolation on gaps among different laser beams to obtain the space information of the particle size distribution.
And the particle size dynamic change observation module is used for determining the particle size dynamic change of the indoor air particulate matters according to the particle size distribution at each pixel point corresponding to different moments.
Example 3
As shown in fig. 2, the present embodiment provides an indoor air particulate particle size and particle size dynamic change monitoring device, which includes a laser, a plurality of CCD cameras and a processor (not shown in fig. 2);
the laser is used for emitting laser beams to indoor air;
the CCD cameras are arranged on the side surfaces of the laser beams and are used for shooting laser images of the same position of the laser beams from different angles;
the processor being configured to perform the method of any one of claims 1 to 4.
The operation process of the device for executing the monitoring method according to the embodiment is as follows:
firstly, a CCD camera is used for shooting a laser beam, actual measurement information is obtained by extracting gray values of the laser beam in a photo or video, and the gray values are corrected by using fitting coefficients obtained by pre-experiments to obtain scattered light intensity (the scattered light intensity is in direct proportion to the gray value I and can be expressed by gamma I). And then, according to the differences of scattered light intensities obtained by CCD at the same point and different angles, calculating the particle size distribution, and further determining the concentration and the particle size of the particulate matters, so that the spatial distribution information of the concentration and the particle size of the particulate matters can be obtained at the same time.
Specifically, step 1: and placing the lasers according to the area of the experimental place and the measurement dimension (two-dimensional or three-dimensional), and vertically installing the CCD camera. The number of lasers and CCD cameras is adjusted according to the requirements of measuring fields and resolution.
For acquisition of measurement two-dimensional (plane) particle size distribution information, lasers can be arranged in a row with a distance of 20-40cm, and the lasers are arranged as a matrix when the measurement three-dimensional (space) particle size distribution information is measured.
Step 2: turning on a laser to emit a laser beam; simultaneously, the CCD camera synchronously shoots laser images emitted by the laser on the side face.
Step 3: extracting a gray value I of a laser beam in an image shot by a camera, and carrying a scattering angle and the gray value I into a relation between the gray value and the g value to obtain a particle size characteristic value g;
step 4: a series of pre-experiments are carried out in a laboratory, a particle generator is used for sequentially generating particles with known particle sizes, a scene with relatively uniform concentration and particle size is constructed, and the relationship between g value and particle size distribution is obtained.
Step 5: and (3) converting the g value obtained in the step (5) into the particle size distribution by using the relational expression of the g value and the particle size distribution obtained in the step (4).
Step 6: and carrying out the above steps on each point of each laser beam in the photo, and carrying out simple linear interpolation calculation between different laser beams to obtain the spatial information of the particle size distribution. And processing each frame of the video shot by the CCD, and then carrying out dynamic multidimensional monitoring on the particle size distribution.
Wherein steps 3 to 6 are performed in a processor.
In this specification, each embodiment is mainly described in the specification as a difference from other embodiments, and the same similar parts between the embodiments are referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (9)
1. The method for monitoring the particle size and the dynamic change of the particle size of indoor air particles is characterized by comprising the following steps:
acquiring a plurality of laser images of an indoor target area; each laser image comprises a plurality of laser beams; the laser images are obtained by shooting a plurality of CCD cameras distributed on the side surfaces of the laser beams in a one-to-one correspondence manner; the plurality of laser images are images of the same position of the laser beam, which are respectively shot by the CCD cameras from different angles;
extracting a gray value of each pixel point in each laser beam for each laser beam of each laser image, and determining a scattering angle at each pixel point;
for each pixel point, bringing the gray value and the scattering angle corresponding to the same pixel point in a plurality of laser images into a relation between the gray value and the particle size characteristic value to obtain the particle size characteristic value of air particles at each pixel point;
for each pixel point, determining the particle size distribution at each pixel point according to the particle size characteristic value and the relation between the particle size characteristic and the particle size distribution; the relation between the particle size characteristics and the particle size distribution is predetermined through experiments; the particle size distribution comprises particle size information of indoor air particles;
determining the particle size distribution space information of indoor air particles according to the particle size distribution at each pixel point;
and determining the dynamic change of the particle size of the indoor air particles according to the particle size distribution at each pixel point corresponding to different moments.
2. The method of claim 1, wherein the gray value versus particle size characteristic value relationship is:
wherein g is a particle size characteristic value, θ is a scattering angle, I is an extracted gray value, and p 1 ，p 2 Is a coefficient.
3. The method according to claim 2, wherein for each of the pixel points, the step of bringing the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images into a relation between the gray value and the particle size feature value to obtain the particle size feature value of the air particulate matter at each of the pixel points comprises:
taking the gray value and the scattering angle corresponding to the same pixel point in a plurality of laser images as a data set;
for each data set, respectively bringing the gray value and the scattering angle in the data set into the relation between the gray value and the particle size characteristic value to obtain an equation set to be solved; the equation set to be solved comprises a plurality of equations to be solved;
for the coefficient p in the equation to be solved 1 Sum coefficient p 2 And solving the particle size characteristic value g to obtain the particle size characteristic value g corresponding to each data set, namely the particle size characteristic value of the air particulate matters at each pixel point.
4. The method according to claim 1, wherein the determining the spatial information of the particle size distribution of the indoor air particulate matter according to the particle size distribution at each of the pixel points specifically includes:
and according to the particle size distribution of all the pixel points of each laser beam in the laser image, performing linear interpolation on gaps among different laser beams to obtain the space information of the particle size distribution.
5. A system for monitoring particle size and dynamic change of particle size of indoor air particulate matter according to the method of any one of claims 1 to 4, wherein the system comprises:
the image acquisition module is used for acquiring a plurality of laser images of the indoor target area; each laser image comprises a plurality of laser beams; the laser images are obtained by shooting a plurality of CCD cameras distributed on the side surfaces of the laser beams in a one-to-one correspondence manner; the plurality of laser images are images of the same position of the laser beam, which are respectively shot by the CCD cameras from different angles;
the gray scale and scattering angle acquisition module is used for extracting the gray scale value of each pixel point in each laser beam for each laser beam of each laser image and determining the scattering angle at each pixel point;
the particle size characteristic value acquisition module is used for bringing the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images into a relation between the gray value and the particle size characteristic value to obtain the particle size characteristic value of the air particulate matters at each pixel point;
the particle size distribution acquisition module is used for determining the particle size distribution of each pixel point according to the particle size characteristic value and the relation between the particle size characteristic and the particle size distribution; the relation between the particle size characteristics and the particle size distribution is predetermined through experiments; the particle size distribution comprises particle size information of indoor air particles;
the particle size distribution space information acquisition module is used for determining the particle size distribution space information of indoor air particles according to the particle size distribution at each pixel point;
and the particle size dynamic change observation module is used for determining the particle size dynamic change of the indoor air particulate matters according to the particle size distribution at each pixel point corresponding to different moments.
6. The system of claim 5, wherein the gray value versus particle size characteristic value relationship is:
wherein g is a particle size characteristic value, θ is a scattering angle, I is an extracted gray value, and p 1 ，p 2 Is a coefficient.
7. The system of claim 6, wherein the particle size feature value acquisition module specifically comprises:
the data set construction unit is used for taking the gray value and the scattering angle corresponding to the same pixel point in the plurality of laser images as one data set;
the equation solving unit is used for respectively bringing the gray value and the scattering angle in each data set into the relation between the gray value and the particle size characteristic value to obtain an equation set to be solved; the equation set to be solved comprises a plurality of equations to be solved;
a particle size characteristic value determining unit for determining the coefficient p in the equation to be solved 1 Sum coefficient p 2 And solving the particle size characteristic value g to obtain the particle size characteristic value g corresponding to each data set, namely the particle size characteristic value of the air particulate matters at each pixel point.
8. The system of claim 5, wherein the particle size distribution spatial information acquisition module specifically comprises:
and according to the particle size distribution of all the pixel points of each laser beam in the laser image, performing linear interpolation on gaps among different laser beams to obtain the space information of the particle size distribution.
9. The device for monitoring the particle size and the dynamic change of the particle size of the indoor air particles is characterized by comprising a laser, a plurality of CCD cameras and a processor;
the laser is used for emitting laser beams to indoor air;
the CCD cameras are arranged on the side surfaces of the laser beams and are used for shooting laser images of the same position of the laser beams from different angles;
the processor being configured to perform the method of any one of claims 1 to 4.
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