Multi-focus cooperation-based particulate matter concentration measurement method and device, and measurement equipment

Abstract

The application discloses a kind of particle concentration measurement method and device based on multi-focus coordination and measuring equipment, it is related to suspended particulate matter detection technical field, main purpose is to solve the problem of lower accuracy of existing particulate matter concentration detection.The main include obtaining the pulse signal generated by each of the detector in the preset period, and extracting the respective corresponding correlation pulse signal time sequence of the particulate matter in the gas to be measured from the pulse signal based on the preset time window;According to the consistency of the correlation pulse signal time sequence of particulate matter, the effective particulate matter is screened out, and the inversion particle size of effective particulate matter is obtained by carrying out particle size inversion on effective particulate matter;According to the inversion particle size, the particle size section of effective particulate matter is divided, to calculate the sampling volume of each of the effective particulate matter under different particle size sections;The sampling volume of the effective particulate matter in each particle size section is calculated respectively, and the particulate matter concentration of different particle size sections is obtained.The main purpose is to measure particulate matter concentration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of suspended particulate matter detection, in particular to a particulate matter concentration measurement method and device based on multi-focus cooperation, and a measurement equipment. BACKGROUND

[0002] Particulate matter concentration measurement refers to quantitatively analyzing the mass or quantity of solid or liquid particulate matter suspended in the air by a specific technical means to determine its content per unit volume of air. The measurement of particulate matter concentration is of great significance to public health protection (such as the measurement of inhalable fine particulate matter such as PM2.5) and environmental quality assessment (such as the concentration limit of particulate matter such as PM2.5 and PM10 as the basis for evaluating whether the air quality meets the standard internationally). Since when light irradiates the particulate matter suspended in the air, scattering occurs, therefore, the concentration and particle size of the particulate matter can be calculated by detecting the intensity and other characteristics of the scattered light by a sensor.

[0003] At present, the existing single-point sensor has an irreconcilable contradiction between signal-to-noise ratio (SNR) and anti-coincidence error ability due to its physical structure limitation: increasing the laser power to enhance the small particle signal will cause the large particle signal to be more easily saturated and the coincidence error to be aggravated; reducing the power cannot detect small particles, resulting in low accuracy of particulate matter concentration measurement. SUMMARY

[0004] Therefore, the present application provides a particulate matter concentration measurement method and device based on multi-focus cooperation and a measurement equipment, which mainly aims to solve the problem of low accuracy of existing particulate matter concentration measurement.

[0005] According to one aspect of the present application, a particulate matter concentration measurement method based on multi-focus cooperation is provided, comprising:

[0006] obtaining pulse signals generated by each of the detectors within a preset time period, and extracting a correlation pulse signal time sequence of each of the particulate matters in the gas to be measured from the pulse signals based on a preset time window;

[0007] screening out effective particulate matters according to the consistency of the correlation pulse signal time sequence of the particulate matters, and performing particle size inversion on the effective particulate matters to obtain the inverted particle size of the effective particulate matters;

[0008] dividing the effective particulate matters into different particle size sections according to the inverted particle size to calculate the sampling volume of each of the effective particulate matters in different particle size sections;

[0009] calculating the concentration of the effective particulate matters in each particle size section to obtain the particulate matter concentration in different particle size sections.

[0010] Further, the process of extracting the correlation pulse signal time sequence of any particle includes:

[0011] extracting pulse signal time sequences occurring in the same preset time window, wherein the preset time window is determined based on the preset flow rate and the distance between the focal points;

[0012] calculating a consistency parameter between each pulse signal in the pulse signal time sequence, wherein the consistency parameter is the ratio of the pulse signal with the minimum voltage value to the pulse signal with the maximum voltage value;

[0013] if the consistency parameter is greater than or equal to a first preset consistency parameter threshold, and the time sequence between each pulse signal matches the order of the same particle passing through each focal point, then the pulse signal time sequence is determined as the correlation pulse signal time sequence of the particle, wherein each correlation pulse signal in the correlation pulse signal time sequence is the pulse signal generated when the correlated particle passes through each focal point in turn.

[0014] Further, the process of screening out effective particles according to the consistency of the correlation pulse signal time sequence of the particle includes:

[0015] if the consistency parameter of the correlation pulse signal time sequence is greater than or equal to a second preset consistency parameter threshold, then the particle is determined as an effective particle, and the signal quality of the correlation pulse signal time sequence is determined as level one, wherein the second preset consistency parameter threshold is greater than the first preset consistency parameter threshold, and the signal quality is used to determine the selection of the particle size inversion strategy;

[0016] In the case where the consistency parameter of the correlation pulse signal time sequence is less than the second preset consistency parameter threshold, the first time interval between each two correlation pulse signals is calculated, and the focal point-to-focal point flight speed of the particle is calculated according to the distance between the two focal points corresponding to the first time interval, if the focal point-to-focal point flight speed satisfies the flight speed verification condition, then the particle is determined as an effective particle, and the signal quality of the correlation pulse signal time sequence is determined as level two, wherein the signal quality of the level one correlation pulse signal time sequence is higher than that of the level two correlation pulse signal time sequence.

[0017] Further, the process of performing particle size inversion on the effective particle to obtain the inversion particle size of the effective particle includes:

[0018] In the case where the signal quality of the correlation pulse signal time sequence is level one, the average scattered light intensity is determined according to the mean value of all correlation pulse signals, and the particle size of the average scattered light intensity is matched from the pre-constructed particle size-light intensity calibration curve function, to serve as the inversion particle size of the effective particle.

[0019] When the signal quality of the associated pulse signal time series is level two, the second time interval between every two adjacent associated pulse signals is extracted, and the inverted particle size of the particles is obtained based on the second time interval, or the inverted particle size of the particles is matched from the pre-constructed particle size light intensity calibration curve function based on the associated pulse signal with the largest voltage value.

[0020] Furthermore, the process of calculating the sampling volume of any effective particulate matter within any particle size range includes:

[0021] Calculate the single-focal sampling volume of the effective particulate matter at any focal point, and take the average value of all single-focal sampling volumes of the effective particulate matter as the sampling volume of the effective particulate matter;

[0022] Calculating the single-focus sampling volume of the effective particulate matter at any focal point specifically includes: for the associated pulse signal of the focal point, extracting the rising edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and the falling edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and taking the difference between the falling edge time point and the rising edge time point as the time taken for the effective particulate matter to pass through the detection area of ​​the focal point;

[0023] The target average velocity matching the current particle size range is retrieved from a pre-calibrated set of particle size range and average velocity mapping relationships. The average velocity in the set of particle size range and average velocity mapping relationships is calculated based on standard measurement values ​​of particles of different sizes within the particle size range.

[0024] Based on the target average velocity of the effective particulate matter, the time taken for it to pass through the detection area of ​​the focal point, and the cross-sectional area of ​​the detection area, the single-point sampling volume of the effective particulate matter at the focal point is calculated.

[0025] Furthermore, the particulate matter concentration includes particulate matter number concentration and / or particulate matter mass concentration;

[0026] The calculation process for the number concentration of the particulate matter for any particle size range includes:

[0027] Determine the total number of effective particles contained in the particle size range, and calculate the total sampling volume of effective particles in the particle size range;

[0028] Calculate the ratio of the total number of effective particles to the total sampling volume within the particle size range to obtain the particle number concentration within the particle size range;

[0029] The calculation process for the particulate matter mass concentration for any particle size range includes:

[0030] The single-particle volume of the effective particulate matter is calculated based on the inverted particle size of the effective particulate matter, and the effective particulate matter density of the particle size range is retrieved.

[0031] The particle mass concentration of the particle size range is calculated based on the single-particle volume, single-focus sampling volume, and effective particle density of all effective particles in the range.

[0032] Furthermore, after obtaining the particulate matter mass concentration of the gas to be tested in different particle size ranges, the method further includes:

[0033] The particulate matter mass concentration for any particle size range was optimized using the following method:

[0034] Obtain particulate matter mass concentrations for multiple consecutive time periods preceding the current time period and signal quality levels for multiple correlated pulse signal time series within each time period;

[0035] For each time period, the signal quality parameters for that time period are calculated based on the number of associated pulse signal time series with different signal quality levels.

[0036] Weights are assigned based on signal quality parameters for each time period to determine the weight coefficients for different time periods;

[0037] The optimized particulate matter concentration for the specified particle size range is obtained by weighted summation based on the particulate matter mass concentration and weighting coefficients at different time periods.

[0038] Furthermore, before acquiring the pulse signals generated by each of the detectors within the preset time period, the method further includes:

[0039] The original pulse signal generated by the detector is amplified to obtain the amplified original pulse signal.

[0040] The amplified original pulse signal is filtered to obtain a pulse signal.

[0041] According to another aspect of the present invention, a particulate matter concentration measuring device based on multifocal synergy is provided, comprising:

[0042] The extraction module is used to acquire the pulse signals generated by each detector within a preset time period, and extract the time series of the associated pulse signals corresponding to the particulate matter in the gas to be tested from the pulse signals based on a preset time window.

[0043] The particle size inversion module is used to screen out effective particles based on the consistency of the time series of the associated pulse signals of the particles, and to perform particle size inversion on the effective particles to obtain the inverted particle size of the effective particles.

[0044] The sampling volume calculation module is used to divide the effective particulate matter into particle size segments based on the inverted particle size, so as to calculate the sampling volume of each effective particulate matter in different particle size segments.

[0045] The concentration calculation module is used to calculate the concentration of the effective particulate matter in each particle size range, so as to obtain the particle concentration in different particle size ranges.

[0046] Furthermore, the extraction module includes:

[0047] An extraction unit is used to extract a pulse signal time sequence that appears within the same preset time window, wherein the preset time window is determined based on the preset flow rate and the distance between each focus;

[0048] The first calculation unit is used to calculate the consistency parameter between each pulse signal in the pulse signal time series, wherein the consistency parameter is the ratio of the pulse signal with the smallest voltage value to the pulse signal with the largest voltage value;

[0049] The first determining unit is configured to determine the pulse signal time sequence as the associated pulse signal time sequence of the particles if the consistency parameter is greater than or equal to the first preset consistency parameter threshold and the timing of each pulse signal matches the order in which the same particle passes through each focal point. The associated pulse signal in the associated pulse signal time sequence is the pulse signal generated when the associated particles pass through each focal point in sequence.

[0050] Furthermore, the particle size inversion module includes:

[0051] The second determining unit is configured to determine the particulate matter as a valid particulate matter if the consistency parameter of the associated pulse signal time series is greater than or equal to a second preset consistency parameter threshold, and to determine the signal quality of the associated pulse signal time series as level one, wherein the second preset consistency parameter threshold is greater than the first preset consistency parameter threshold, and the signal quality is used to determine the particle size inversion strategy.

[0052] The third determining unit is used to calculate the first time interval between every two associated pulse signals when the consistency parameter of the associated pulse signal time series is less than the second preset consistency parameter threshold, calculate the inter-focal flight speed of the particulate matter based on the distance between the two focal points corresponding to the first time interval, and determine the particulate matter as a valid particulate matter if the inter-focal flight speed meets the flight speed verification condition, and determine the signal quality of the associated pulse signal time series as level two, wherein the signal quality of the level one associated pulse signal time series is higher than that of the level two associated pulse signal time series.

[0053] Furthermore, the particle size inversion module also includes:

[0054] The fourth determining unit is used to determine the average scattered light intensity based on the mean of all associated pulse signals when the signal quality of the associated pulse signal time series is level one, and to match the particle size of the average scattered light intensity from the pre-constructed particle size light intensity calibration curve function as the inversion particle size of the effective particles.

[0055] The fifth determining unit is used to extract the second time interval between every two adjacent associated pulse signals when the signal quality of the associated pulse signal time series is level two, and to obtain the inverted particle size of the particulate matter based on the second time interval, or to match the inverted particle size of the particulate matter from the pre-constructed particle size light intensity calibration curve function based on the associated pulse signal with the largest voltage value.

[0056] Furthermore, the sampling volume calculation module includes:

[0057] The second calculation unit is used to calculate the single-focus sampling volume of the effective particulate matter at any focus, specifically including: for the associated pulse signal of the focus, extracting the rising edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and the falling edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and using the difference between the falling edge time point and the rising edge time point as the time taken for the effective particulate matter to pass through the detection area of ​​the focus;

[0058] The retrieval unit is used to retrieve the target average velocity matching the current particle size segment from a pre-calibrated set of particle size segment and average velocity mapping relationships, wherein the average velocity in the set of particle size segment and average velocity mapping relationships is calculated based on standard measurement values ​​of particles of different sizes in the particle size segment.

[0059] The third calculation unit is used to calculate the single-point sampling volume of the effective particulate matter at the focal point based on the target average velocity of the effective particulate matter, the time taken to pass through the detection area of ​​the focal point, and the cross-sectional area of ​​the detection area.

[0060] The sixth determining unit is used to take the average value of all single-focus sampling volumes of the effective particulate matter as the sampling volume of the effective particulate matter.

[0061] Furthermore, the concentration calculation module includes:

[0062] The fourth calculation unit is used to determine the total number of effective particles contained in the particle size range and to calculate the total sampling volume of effective particles in the particle size range.

[0063] The number concentration calculation unit is used to calculate the ratio of the total number of effective particles to the total sampling volume within the particle size range, and to obtain the particle number concentration within the particle size range.

[0064] The fifth calculation unit is used to calculate the single-particle volume of the effective particulate matter based on the inverted particle size of the effective particulate matter, and to retrieve the effective particulate matter density of the particle size range.

[0065] The mass concentration calculation unit is used to calculate the particulate matter mass concentration of the particle size range based on the single particle volume, single focal sampling volume and effective particulate matter density of all effective particulate matter in the particle size range.

[0066] Furthermore, the device also includes:

[0067] The optimization module is used to obtain the particulate matter mass concentration of multiple consecutive time periods before the current time period and the signal quality level of multiple associated pulse signal time series within each time period; for each time period, the signal quality parameter of the time period is calculated based on the number of associated pulse signal time series with different signal quality levels; weights are assigned based on the signal quality parameters of each time period to determine the weight coefficients of different time periods; and a weighted sum is performed based on the particulate matter mass concentration and weight coefficients of different time periods to obtain the optimized particulate matter mass concentration of the particle size range.

[0068] According to another aspect of the present invention, a measuring device is provided, comprising: a processor, at least one semiconductor laser diode, at least one convex lens, at least one beam splitter, at least two lens groups, a detector matching the number of lens groups, and a signal processor;

[0069] The semiconductor laser diode is used to emit a diverging laser beam toward the convex lens;

[0070] The convex lens is used to convert the diverging laser beam into collimated parallel light;

[0071] The beam splitter is used to split the collimated parallel light into two laser beams;

[0072] Any of the lens groups is used to focus a corresponding laser beam into a single focal point, with the focal points arranged collinearly.

[0073] The detector is used to generate pulse signals based on the changes in the intensity of scattered light caused by particles of various sizes passing through the detection area of ​​the corresponding focal point.

[0074] The processor executes the operations corresponding to the above-mentioned multi-focus collaborative particulate matter concentration measurement method;

[0075] The signal processor is used to amplify the original pulse signal generated by the detector through a preamplifier to obtain an amplified original pulse signal; and to filter the amplified original pulse signal through a bandpass filter to obtain a pulse signal.

[0076] By employing the above-described technical solutions, the technical solutions provided by the embodiments of the present invention have at least the following advantages:

[0077] This invention provides a method, apparatus, and measuring device for measuring particulate matter concentration based on multi-focus collaboration. In this embodiment, the invention acquires pulse signals generated by each detector within a preset time period and extracts the associated pulse signal time series corresponding to each particulate matter in the gas to be measured from the pulse signals based on a preset time window. Effective particulate matter is screened based on the consistency of the associated pulse signal time series, and particle size inversion is performed on the effective particulate matter to obtain its inverted particle size. The effective particulate matter is then divided into particle size segments based on the inverted particle size to calculate the sampling volume of each effective particulate matter in different particle size segments. The concentration of the sampled volume of the effective particulate matter in each particle size segment is calculated to obtain the particulate matter concentration in different particle size segments. Through multi-focus collaboration, effective particulate matter screening, and particle size inversion, the interference of random noise and heterogeneous particulate matter signals is effectively suppressed, improving the accuracy and reliability of particulate matter concentration measurement, thereby greatly improving the accuracy of particulate matter concentration measurement.

[0078] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the specification. Furthermore, in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0079] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0080] Figure 1 A flowchart of a particulate matter concentration measurement method based on multi-focus synergy provided by an embodiment of the present invention is shown;

[0081] Figure 2 A flowchart of a particulate matter concentration optimization method provided by an embodiment of the present invention is shown;

[0082] Figure 3 A block diagram of a particulate matter concentration measurement device based on multi-focus coordination provided by an embodiment of the present invention is shown.

[0083] Figure 4 A schematic diagram of a two-focus measuring device provided in an embodiment of the present invention is shown;

[0084] Figure 5 A schematic diagram of the structure of a measuring device provided in an embodiment of the present invention is shown. Detailed Implementation

[0085] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0086] To address the issue of low accuracy in particulate matter concentration measurement, this invention provides a multi-focal collaborative particulate matter concentration measurement method. This method involves filling a measuring device with a target gas at a preset flow rate to measure particulate matter concentration. The measuring device includes at least two focal points and detectors corresponding to each focal point. The detectors generate pulse signals based on changes in the intensity of scattered light caused by particles of various sizes passing through the detection area of ​​the corresponding focal point. Furthermore, the measuring device also includes a processor, such as a microcontroller or other types of processors, which are not limited in this embodiment. In this embodiment, the processor of the measuring device is used as the execution entity to describe the particulate matter concentration measurement method.

[0087] like Figure 1 As shown, the method includes:

[0088] 101. Obtain the pulse signals generated by each of the detectors within a preset time period, and extract the time series of the associated pulse signals corresponding to the particulate matter in the gas to be tested from the pulse signals based on a preset time window.

[0089] In this embodiment of the invention, to determine particulate matter concentration based on pulse signals, pulse signals generated by each detector in the device are collected within a preset time period. The preset time period can be the time required for a single measurement or multiple measurements to be completed by the measuring device. The associated pulse signal time series is a time series of multiple pulse signals generated by the same particulate matter at different focal points; the pulse signal generated by this particulate matter is thus the associated pulse signal. The focal points in the measuring device are collinearly arranged light spots, with a spot diameter less than or equal to 50 μm, and the distance between focal points is preferably 10.0 mm ± 0.1 mm. When the gas to be measured is introduced into the measuring device, the gas flows sequentially through each focal point at a flow rate corresponding to a preset flow rate, causing light scattering at the focal point and resulting in changes in light intensity. A photodetector configured at each focal point collects the scattered light signal from the detection area (spot range) corresponding to that focal point, and generates a pulse signal through photoelectric conversion.

[0090] It should be noted that by extracting the time series of associated pulse signals through a preset time window, the signal corresponding to each particle when it passes through the detection area can be accurately located, avoiding confusion between signals of different particles, effectively suppressing random noise and interference from signals of foreign particles, and significantly improving the reliability of signal identification, thereby providing a reliable data foundation for subsequent accurate analysis of particle characteristics.

[0091] 102. Based on the consistency of the time series of the associated pulse signals of the particles, effective particles are screened out, and particle size inversion is performed on the effective particles to obtain the inverted particle size of the effective particles.

[0092] In this embodiment of the invention, the consistency of the correlated pulse signal time series refers to the deviation between multiple correlated pulse signals corresponding to the current particle. Theoretically, the pulse signals generated by the same particle at different focal points should be highly consistent. If the differences between the correlated pulse signals in the same correlated pulse signal time series are large (low consistency), it indicates that some correlated pulse signals may be noise or interference signals. In order to improve the accuracy of subsequent data processing, it is necessary to remove signals with low consistency and retain only valid signals, that is, to screen out valid particles from the particles. Then, for each valid particle, the inverted particle size corresponding to each valid particle is determined by particle size inversion.

[0093] It should be noted that screening valid particulate matter based on the consistency of the signal time series can effectively eliminate interference from noise and invalid signals, ensuring that the analyzed object is real particulate matter. Performing particle size inversion on valid particulate matter can accurately obtain particle size information, providing key parameters for subsequent precise particle size segmentation and concentration calculation, thus improving the accuracy of particulate matter size measurement.

[0094] 103. Divide the effective particulate matter into particle size segments based on the inverted particle size, and calculate the single-focus sampling volume of each effective particulate matter in different particle size segments.

[0095] In this embodiment of the invention, after obtaining the inverted particle size of the effective particles, all effective particles are divided into corresponding particle size segments according to preset particle size ranges. For each particle size segment, the single-focus sampling volume is calculated individually. The single-focus sampling volume is the sampling volume of the effective particles in the detection area of ​​one focus. This single-focus sampling volume can be directly calculated based on the air pump flow rate, the sampling time (time consumed) for the effective particles to pass through the detection area, and the spot area, or it can be calculated based on the average velocity of the current particle size segment. This embodiment of the invention does not impose specific limitations.

[0096] It should be noted that classifying effective particulate matter by particle size helps to gain a deeper understanding of the distribution of particles of different sizes. Calculating the single-focal sampling volume of each effective particulate matter in different size ranges can take into account the differences in particle size during the sampling process, providing more realistic volume data for accurately calculating particulate matter concentration.

[0097] 104. Calculate the concentration of the effective particulate matter in each particle size range by performing single-focus sampling volume calculations to obtain the particulate matter concentration in different particle size ranges.

[0098] In this embodiment of the invention, concentration calculations are performed for each particle size segment, providing a detailed understanding of the concentration distribution of particles of different sizes in the gas being tested. This method of concentration calculation by particle size segment can more accurately reflect the actual concentration of particulate matter, providing more detailed and accurate data support for fields such as environmental monitoring and industrial production.

[0099] In one embodiment of the present invention, for further explanation and limitation, the process of extracting the time series of the associated pulse signal of any particulate matter includes:

[0100] Extract the time series of pulse signals that appear within the same preset time window;

[0101] Calculate the consistency parameter between each pulse signal in the pulse signal time series;

[0102] If the consistency parameter is greater than or equal to the first preset consistency parameter threshold, and the timing of each pulse signal matches the order in which the same particle passes through each focal point, then the pulse signal time sequence is determined as the associated pulse signal time sequence of the particle.

[0103] In this embodiment of the invention, a preset time window is adaptively configured within a time window threshold based on a preset flow rate and the distance between each focus point. Specifically, the preset time window is determined based on the preset flow rate and the distance between each focus point. The time window threshold is 50–200 μs, and the preset time window is preferably 100 μs. The pulse signals are divided according to the preset time window to obtain a pulse signal time sequence within the same preset time window. The consistency parameter of the pulse signals in the pulse signal time sequence is calculated, which is the ratio of the pulse signal with the smallest voltage value to the pulse signal with the largest voltage value. Only when the consistency parameter is greater than or equal to a first preset consistency parameter threshold, and the timing of each pulse signal conforms to the sequential passing of the same particle through each focus point, are the pulse signals in this sequence determined as a valid signal group originating from the same particle, i.e., the associated pulse signal time sequence corresponding to the particle. Each associated pulse signal in the associated pulse signal time sequence is a pulse signal generated when the associated particle passes through each focus point sequentially. Taking two focus points as an example, the formula for calculating the consistency parameter is:

[0104] R = min(H1,H2) / max(H1,H2);

[0105] H1 and H2 represent the pulse signals generated by the particulate matter at the two focal points.

[0106] It should be noted that the pulse signals used to extract the time series of correlated pulse signals can be preprocessed pulse signals or raw pulse signals collected by each detector, which are amplified by a preamplifier and filtered by a bandpass filter to suppress low-frequency drift and high-frequency noise.

[0107] In one embodiment of the present invention, for further explanation and limitation, effective particulate matter is screened based on the consistency of the time series of the associated pulse signals of the particulate matter, including:

[0108] If the consistency parameter of the correlated pulse signal time series is greater than or equal to the second preset consistency parameter threshold, then the particulate matter is determined to be valid particulate matter, and the signal quality of the correlated pulse signal time series is determined to be level one.

[0109] If the consistency parameter of the correlated pulse signal time series is less than the second preset consistency parameter threshold, the first time interval between every two correlated pulse signals is calculated. Based on the distance between the two focal points corresponding to the first time interval, the interfocal flight speed of the particulate matter is calculated. If the interfocal flight speed meets the flight speed verification condition, the particulate matter is determined to be a valid particulate matter, and the signal quality of the correlated pulse signal time series is determined to be level two.

[0110] In this embodiment of the invention, a first preset consistency parameter threshold is used to determine whether each pulse signal in the sequence originates from the same particle, while a second preset consistency parameter threshold is used to screen whether the event of the particle passing through the focal point is a valid event, thereby determining whether the particle is a valid particle. Therefore, the second preset consistency parameter threshold needs to be more stringent than the first preset consistency parameter threshold, and the second preset consistency parameter threshold is greater than the first preset consistency parameter threshold. For example, if the second preset consistency parameter threshold is 0.8, then the first preset consistency parameter threshold can be 0.7. If the calculated consistency parameter is greater than or equal to the second preset consistency parameter threshold, it indicates that the signal quality of the current associated pulse signal time series is high, and it is marked as signal quality level one. If the calculated consistency parameter is less than the second preset consistency parameter threshold, it indicates that the signal quality of the current associated pulse signal time series is low, and it is marked as signal quality level two. That is, the signal quality of the level one associated pulse signal time series is higher than that of the level two associated pulse signal time series. Here, signal quality is used to determine the selected particle size inversion strategy, that is, different particle size inversion strategies are adopted under different signal quality levels.

[0111] For the time series of correlated pulse signals at signal quality level 2, the validity is further identified based on the average flight velocity of particles between focal points. The distance between the two focal points corresponding to the first time interval can be the distance between two adjacent focal points or the distance between any two focal points. For example, given three focal points A, B, and C, this distance can be any segment of the distance between A and B, A and C, or C and B. The first time interval is the time interval between the correlated pulse signals emitted by the detectors corresponding to the two focal points at this distance. The calculation time point can be the start time of the two pulse signals or the peak time of the pulse signals; this embodiment of the invention does not impose a specific limitation. The formula for calculating the flight velocity between focal points is expressed as:

[0112] ;

[0113] in, Indicates the speed of flight between focal points. Indicates the distance between two foci. Indicates the first time interval.

[0114] After obtaining the interfocal velocity, particles whose interfocal velocity falls within the velocity verification range are considered valid particles and included in subsequent concentration calculations. If the velocity falls outside the range, the particle data is discarded and not included in the concentration calculation. The velocity verification conditions are calculated based on the air pump flow rate and the air path diameter. For example, when the air pump flow rate is Q=1.2L / min and the air path diameter is 5mm, the particle velocity from 0.3μm to 10μm is estimated based on the Poisson flow distribution, and the range is widened to obtain [0.3, 3.0] m / s as the velocity verification condition.

[0115] In one embodiment of the present invention, for further explanation and limitation, the step of performing particle size inversion on the effective particulate matter to obtain the inverted particle size of the effective particulate matter includes:

[0116] When the signal quality of the associated pulse signal time series is at level one, the average scattered light intensity is determined based on the mean of all associated pulse signals, and the particle size of the average scattered light intensity is matched from the pre-constructed particle size intensity calibration curve function to serve as the inversion particle size of the effective particles.

[0117] When the signal quality of the associated pulse signal time series is level two, the second time interval between every two adjacent associated pulse signals is extracted, and the inverted particle size of the particles is obtained based on the second time interval, or the inverted particle size of the particles is matched from the pre-constructed particle size light intensity calibration curve function based on the associated pulse signal with the largest voltage value.

[0118] In this embodiment of the invention, during the particle size inversion process, different inversion strategies are adopted for effective particles at different signal quality levels. Specifically, for first-level quality signals, since the signal quality and reliability are high, the average value of each associated pulse signal (voltage signal) can be directly calculated. The corresponding scattered light intensity (average scattered light intensity) is determined by the average value of the scattered light intensity voltage. Then, the average scattered light intensity is substituted into the pre-constructed particle size light intensity calibration curve function to calculate the particle size corresponding to the current average scattered light intensity. The pre-constructed particle size light intensity calibration curve function is built based on a large amount of scattered light intensity data measured under standard experimental conditions for particles of different sizes, and can accurately calibrate the scattered light intensity corresponding to particles of different sizes.

[0119] For secondary quality signals, due to their lower quality, the scattered light intensity of particles varies significantly at each focal point. Therefore, the time interval between adjacent correlated pulse signals is used for inversion, or the correlated pulse signal with the highest voltage value is used as the inversion basis. The inversion of the time interval between adjacent correlated pulse signals is based on the distribution of the time intervals between adjacent pulse signals generated when particles of different sizes pass through adjacent focal points under a given experimental environment, constructing a calibration curve function between particle size and time interval. When particles pass through different focal points, due to factors such as velocity, they exhibit a certain interval pattern in time, and this interval is correlated with the particle size. Therefore, the particle size can be inverted from the flight time between two focal points.

[0120] Similarly, under the condition of signal quality level 2, the correlated pulse signal with the largest voltage value is selected from the correlated pulse signals. The voltage value reflects the combined effect of the particle on the detector when it passes through the focal point. Although the overall signal quality is not high, the pulse signal with the largest voltage value contains key information about the particle size to a certain extent, thus avoiding underestimation of the particle size. In actual operation, the scattered light intensity corresponding to the correlated pulse signal with the largest voltage value is substituted into a pre-constructed particle size intensity calibration curve function. The particle size value that best matches this scattered light intensity is found in the function and determined as the inversion particle size of the current effective particle.

[0121] In one embodiment of the present invention, for further explanation and limitation, the process of calculating the sampling volume of any effective particulate matter in any particle segment includes:

[0122] Calculate the single-focal sampling volume of the effective particulate matter at any focal point, and take the average value of all single-focal sampling volumes of the effective particulate matter as the sampling volume of the effective particulate matter;

[0123] Calculating the single-focus sampling volume of the effective particulate matter at any focal point specifically includes: for the associated pulse signal of the focal point, extracting the rising edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and the falling edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and taking the difference between the falling edge time point and the rising edge time point as the time taken for the effective particulate matter to pass through the detection area of ​​the focal point;

[0124] The target average velocity matching the current particle size range is retrieved from a pre-calibrated set of particle size range and average velocity mapping relationships. The average velocity in the set of particle size range and average velocity mapping relationships is calculated based on standard measurement values ​​of particles of different sizes within the particle size range.

[0125] Based on the target average velocity of the effective particulate matter, the time taken for it to pass through the detection area of ​​the focal point, and the cross-sectional area of ​​the detection area, the single-point sampling volume of the effective particulate matter at the focal point is calculated.

[0126] In this embodiment of the invention, the formula for calculating the single-focus sampling volume is:

[0127] ;

[0128] in, This represents the single-focus sampling volume of effective particulate matter i. The cross-sectional area (spot area) of the detection region at the focal point. This indicates the time it takes for effective particulate matter to pass through the detection area of ​​the focal point. This indicates the target average velocity of the effective particulate matter.

[0129] The time it takes for effective particles to pass through the focal detection region can be determined based on the associated pulse signal corresponding to the focal point. Specifically, first, find the rising edge time point where the voltage value reaches half of the pulse peak voltage during the rising edge, and the falling edge time point where the voltage value equals half of the pulse peak voltage during the falling edge. The difference between these two times is taken as the time it takes for effective particles to pass through the focal detection region. The average velocity in the particle size range and average velocity mapping relationship set is calculated based on standard measurements of particles of different sizes within the specified particle size range. Specific methods include: calibration in the laboratory using monodisperse standard particles (e.g., 0.5µm, 1.0µm, 2.5µm photoluminescence spectroscopic analysis spheres); introducing standard particles of a certain particle size range at a known, stable airflow velocity; measuring the instantaneous velocity of a large number of particles in that particle size range; statistically obtaining the average velocity of particles in that particle size range; and after obtaining the single-focal sampling volume of each effective particle, averaging the single-focal sampling volumes and using the average single-focal sampling volume as the current effective particle sampling volume. Through the above process, each particle has its own unique sampling volume, realizing dynamic volume correction and avoiding the errors caused by the fixed sampling volume in traditional methods.

[0130] It should be noted that by accurately extracting the key time points of the rising and falling edges of the pulse signal to calculate the time it takes for particles to pass through the detection area, the transit time of particles in that area can be more accurately reflected, reducing time deviations caused by signal fluctuations or measurement errors. Retrieving the average velocity from a pre-calibrated mapping set ensures the accuracy and reliability of the velocity data, avoiding uncertainties that may be introduced by real-time velocity measurement. Calculating the single-point sampling volume by combining the target average velocity, transit time, and cross-sectional area allows the sampling volume to be dynamically adjusted according to the effective particle flight time, truly reflecting the actual sampling situation of effective particles at that focal point. This improves the accuracy and stability of single-focal sampling volume calculation, providing a reliable data foundation for subsequent particle analysis and research.

[0131] In one embodiment of the present invention, for further explanation and limitation, the calculation process of the particulate matter number concentration for any particle size range includes:

[0132] Determine the total number of effective particles contained in the particle size range, and calculate the total sampling volume of effective particles in the particle size range;

[0133] Calculate the ratio of the total number of effective particles to the total sampling volume within the particle size range to obtain the particle number concentration within the particle size range;

[0134] The calculation process for the particulate matter mass concentration for any particle size range includes:

[0135] The single-particle volume of the effective particulate matter is calculated based on the inverted particle size of the effective particulate matter, and the effective particulate matter density of the particle size range is retrieved.

[0136] The particle mass concentration of the particle size range is calculated based on the single-particle volume, single-focus sampling volume, and effective particle density of all effective particles in the range.

[0137] In this embodiment of the invention, particulate matter concentration includes particulate matter number concentration and / or particulate matter mass concentration, which can be customized according to application requirements. The calculation of particulate matter number concentration requires counting the total number of all effective particles in the current particle size range, i.e., the total number of effective particles, and the sum of the sampling volumes of all effective particles, i.e., the total sampling volume. The formula for calculating particulate matter number concentration is expressed as:

[0138] ;

[0139] in, This represents the particulate matter number concentration in the j-th particle size range. This represents the total number of effective particles in the j-th particle size segment. This represents the sampling volume of the i-th effective particulate matter, which belongs to the j-th particle size range. The calculation of particulate matter mass concentration requires first matching the effective particulate matter density corresponding to the current particle size range from the density correspondence of different particle size ranges obtained through pre-experimental measurements, and then using the inverted particle size of each effective particulate matter. Calculate the volume of a single particle Therefore, the particulate matter mass concentration is calculated based on the effective particulate matter density, the volume of each effective particulate matter particle, and the sampling volume. The calculation formula is expressed as:

[0140] ;

[0141] in, This represents the particulate matter mass concentration in the j-th particle size range. This represents the effective particulate matter density in the j-th particle size segment. This represents the sampling volume of the i-th effective particulate matter. This represents the volume of a single particle of the i-th effective particulate matter. The inverted particle size of the i-th effective particulate matter belongs to the j-th particle size range. The effective particulate matter density can be obtained by parallel comparative testing using a PM2.5 monitor based on the β-ray diffraction method and the oscillating balance method, yielding both the measured number concentration and the measured volume concentration. The effective particulate matter density can be calculated based on the ratio of the measured number concentration to the measured volume concentration. The effective particulate matter density of PM2.5 can be set to 1.5 grams per cubic centimeter.

[0142] It should be noted that the above calculation process for particulate matter number concentration and mass concentration can accurately and comprehensively obtain information on the quantity and mass distribution of particulate matter of different particle sizes in the air, providing important technical support and data basis for air quality monitoring, environmental pollution research, health risk assessment and the formulation of related policies.

[0143] In one embodiment of the present invention, for further explanation and limitation, after obtaining the particulate matter mass concentration of the gas to be tested in different particle size ranges, the method further includes:

[0144] like Figure 2 As shown, the particulate matter mass concentration for any particle size range is optimized using the following method:

[0145] 201. Obtain the particulate matter mass concentration of multiple consecutive time periods before the current time period and the signal quality level of multiple associated pulse signal time series within each time period.

[0146] 202. For each time period, calculate the signal quality parameters of that time period based on the number of associated pulse signal time series with different signal quality levels.

[0147] 203. Based on the signal quality parameters of each time period, weights are allocated to determine the weight coefficients for different time periods.

[0148] 204. The particulate matter mass concentration and weighting coefficients at different time periods are weighted and summed to obtain the optimized result of the particulate matter mass concentration for the particle size range.

[0149] In this embodiment of the invention, after obtaining the particulate matter mass concentration of the gas to be tested in different particle size ranges, optimization is performed for any particle size range. First, particulate matter mass concentration data from multiple consecutive time periods preceding the current time period are acquired. Simultaneously, signal quality level information of multiple associated pulse signal time series within each time period is collected. Next, for each time period, the signal quality parameter is calculated based on the number of associated pulse signal time series corresponding to different signal quality levels. Signal quality parameter = (Number of Level 1 signals × 0.7 + Number of Level 2 signals × 0.3) / Total number of signals. For example, if a time period has 50 associated pulse signal time series, of which 35 are Level 1 and 15 are Level 2, the signal quality parameter is (35 × 0.7 + 15 × 0.3) / 50, which is 0.58. Then, weights are allocated based on the signal quality parameters calculated for each time period to determine the weight coefficients corresponding to different time periods. Specifically, time periods with higher signal quality parameters are assigned greater weights, and time periods with lower signal quality parameters are assigned smaller weights. By using the particulate matter mass concentration at different time periods and a predetermined weighting coefficient, a weighted summation operation is performed to obtain the optimized particulate matter mass concentration result for that particle size range. Of course, signal quality can also be determined based on factors such as the signal-to-noise ratio and pulse waveform integrity; this embodiment of the invention does not impose specific limitations.

[0150] Due to various interference factors, the directly measured particulate matter concentration may contain some deviations. For example, the sensor of the monitoring equipment may be affected by environmental factors such as temperature and humidity, leading to inaccurate output pulse signals and thus deviations in the measured particulate matter concentration. These deviations can be corrected by comprehensively analyzing and weighting data from multiple time periods. By assigning weights based on signal quality, particulate matter concentration data with higher signal quality have a greater impact on the final optimized result, making the optimized result closer to the true value. This improves the overall measurement accuracy and provides more accurate data support for air quality assessment and pollution source tracking.

[0151] In specific application scenarios, taking two focal points as an example, such as... Figure 4As shown, the measuring device includes a processor, a semiconductor laser diode, a convex lens, a beam splitter, two lens groups (lens groups A and B), two photodetectors (PD1 and PD2), and two signal processors. The semiconductor laser diode has a wavelength of 650 nm to generate a laser beam with a wavelength of 650 nm and an output power of 30 milliwatts. The convex lens converts the diverging laser beam emitted by the semiconductor laser diode into collimated parallel light. The beam splitter can be 50 / 50, with dimensions of 10 mm × 10 mm × 10 mm, used to split the collimated parallel light into at least two sub-laser beams. The lens groups can be collimating or focusing lenses, each lens group operating independently, processing one laser beam separately to form two collinear focal points with a focal distance of 10.0 mm ± 0.1 mm. The photodetectors have a response wavelength range of 400-1100 nm and a rise time ≤ 10 nanoseconds to ensure the capture of rapid changes in scattered light signals. The signal processor is a 16-bit analog-to-digital converter with a sampling rate of 1 MHz, used for bandpass filtering of the acquired signal, with a filtering frequency range of 100 kHz to 500 kHz. The processor is responsible for running signal processing algorithms, logical judgments, speed calculations, concentration inversion, and data communication functions, specifically executing the aforementioned multi-focal collaborative particulate matter concentration measurement method. A gas pump is used to extract gas according to configuration parameters, ensuring the airflow to be measured passes through focal points A and B at a preset flow rate. Each lens group can independently adjust its focal position and spot size, with a spot diameter not exceeding 50 μm. Calibration of the spot size and the cross-sectional area of ​​the detection region can be achieved through observation and recording using a spot analysis instrument. Standard monodisperse particles of known size (such as polystyrene latex standard spheres) are introduced into the system at a calibrated flow rate. The effective cross-sectional area of ​​the detection region is then calculated by back-calculation using microscopic imaging or by comparison with a standard instrument.

[0152] This invention provides a multi-focus collaborative particulate matter concentration measurement method. In this embodiment, the method acquires pulse signals generated by each detector within a preset time period and extracts the associated pulse signal time series corresponding to each particulate matter in the gas to be measured from the pulse signals based on a preset time window. Effective particulate matter is screened based on the consistency of the associated pulse signal time series, and particle size inversion is performed on the effective particulate matter to obtain its inverted particle size. The effective particulate matter is then divided into particle size segments based on the inverted particle size to calculate the sampling volume of each effective particulate matter in different particle size segments. The concentration of the sampled volume of the effective particulate matter in each particle size segment is calculated to obtain the particulate matter concentration in different particle size segments. Through multi-focus collaboration, effective particulate matter screening, and particle size inversion, the method effectively suppresses random noise and interference from heterogeneous particulate matter signals, improving the accuracy and reliability of particulate matter concentration measurement, thereby significantly improving the accuracy of particulate matter concentration measurement.

[0153] Furthermore, as a response to the above Figure 1 The implementation of the method shown in this invention provides a particulate matter concentration measurement device based on multi-focal synergy, such as... Figure 3 As shown, the device includes:

[0154] Extraction module 31 is used to acquire the pulse signals generated by each detector within a preset time period, and extract the time series of the associated pulse signals corresponding to the particulate matter in the gas to be tested from the pulse signals based on a preset time window.

[0155] The particle size inversion module 32 is used to screen out effective particles based on the consistency of the time series of the associated pulse signals of the particles, and to perform particle size inversion on the effective particles to obtain the inverted particle size of the effective particles.

[0156] The sampling volume calculation module 33 is used to divide the effective particulate matter into particle size segments based on the inverted particle size, so as to calculate the sampling volume of each effective particulate matter in different particle size segments respectively;

[0157] The concentration calculation module 34 is used to calculate the concentration of the effective particulate matter in each particle size range by sampling the volume of each particle size range, so as to obtain the particle concentration of different particle size ranges.

[0158] Furthermore, the extraction module 31 includes:

[0159] An extraction unit is used to extract a pulse signal time sequence that appears within the same preset time window, wherein the preset time window is determined based on the preset flow rate and the distance between each focus;

[0160] The first calculation unit is used to calculate the consistency parameter between each pulse signal in the pulse signal time series, wherein the consistency parameter is the ratio of the pulse signal with the smallest voltage value to the pulse signal with the largest voltage value;

[0161] The first determining unit is configured to determine the pulse signal time sequence as the associated pulse signal time sequence of the particles if the consistency parameter is greater than or equal to the first preset consistency parameter threshold and the timing of each pulse signal matches the order in which the same particle passes through each focal point. The associated pulse signal in the associated pulse signal time sequence is the pulse signal generated when the associated particles pass through each focal point in sequence.

[0162] Furthermore, the particle size inversion module 32 includes:

[0163] The second determining unit is configured to determine the particulate matter as a valid particulate matter if the consistency parameter of the associated pulse signal time series is greater than or equal to a second preset consistency parameter threshold, and to determine the signal quality of the associated pulse signal time series as level one, wherein the second preset consistency parameter threshold is greater than the first preset consistency parameter threshold, and the signal quality is used to determine the particle size inversion strategy.

[0164] The third determining unit is used to calculate the first time interval between every two associated pulse signals when the consistency parameter of the associated pulse signal time series is less than the second preset consistency parameter threshold, calculate the inter-focal flight speed of the particulate matter based on the distance between the two focal points corresponding to the first time interval, and determine the particulate matter as a valid particulate matter if the inter-focal flight speed meets the flight speed verification condition, and determine the signal quality of the associated pulse signal time series as level two, wherein the signal quality of the level one associated pulse signal time series is higher than that of the level two associated pulse signal time series.

[0165] Furthermore, the particle size inversion module 32 also includes:

[0166] The fourth determining unit is used to determine the average scattered light intensity based on the mean of all associated pulse signals when the signal quality of the associated pulse signal time series is level one, and to match the particle size of the average scattered light intensity from the pre-constructed particle size light intensity calibration curve function as the inversion particle size of the effective particles.

[0167] The fifth determining unit is used to extract the second time interval between every two adjacent associated pulse signals when the signal quality of the associated pulse signal time series is level two, and to obtain the inverted particle size of the particulate matter based on the second time interval, or to match the inverted particle size of the particulate matter from the pre-constructed particle size light intensity calibration curve function based on the associated pulse signal with the largest voltage value.

[0168] Furthermore, the sampling volume calculation module 33 includes:

[0169] The second calculation unit is used to calculate the single-focus sampling volume of the effective particulate matter at any focus, specifically including: for the associated pulse signal of the focus, extracting the rising edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and the falling edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and using the difference between the falling edge time point and the rising edge time point as the time taken for the effective particulate matter to pass through the detection area of ​​the focus;

[0170] The retrieval unit is used to retrieve the target average velocity matching the current particle size segment from a pre-calibrated set of particle size segment and average velocity mapping relationships, wherein the average velocity in the set of particle size segment and average velocity mapping relationships is calculated based on standard measurement values ​​of particles of different sizes in the particle size segment.

[0171] The third calculation unit is used to calculate the single-point sampling volume of the effective particulate matter at the focal point based on the target average velocity of the effective particulate matter, the time taken to pass through the detection area of ​​the focal point, and the cross-sectional area of ​​the detection area.

[0172] The sixth determining unit is used to take the average value of all single-focus sampling volumes of the effective particulate matter as the sampling volume of the effective particulate matter.

[0173] Furthermore, the concentration calculation module 34 includes:

[0174] The fourth calculation unit is used to determine the total number of effective particles contained in the particle size range and to calculate the total sampling volume of effective particles in the particle size range.

[0175] The number concentration calculation unit is used to calculate the ratio of the total number of effective particles to the total sampling volume within the particle size range, and to obtain the particle number concentration within the particle size range.

[0176] The fifth calculation unit is used to calculate the single-particle volume of the effective particulate matter based on the inverted particle size of the effective particulate matter, and to retrieve the effective particulate matter density of the particle size range.

[0177] The mass concentration calculation unit is used to calculate the particulate matter mass concentration of the particle size range based on the single particle volume, single focal sampling volume and effective particulate matter density of all effective particulate matter in the particle size range.

[0178] Furthermore, the device also includes:

[0179] The optimization module is used to obtain the particulate matter mass concentration of multiple consecutive time periods before the current time period and the signal quality level of multiple associated pulse signal time series within each time period; for each time period, the signal quality parameter of the time period is calculated based on the number of associated pulse signal time series with different signal quality levels; weights are assigned based on the signal quality parameters of each time period to determine the weight coefficients of different time periods; and a weighted sum is performed based on the particulate matter mass concentration and weight coefficients of different time periods to obtain the optimized particulate matter mass concentration of the particle size range.

[0180] This invention provides a multi-focus collaborative particulate matter concentration measurement device. In this embodiment, the device acquires pulse signals generated by each detector within a preset time period and extracts the associated pulse signal time series corresponding to each particulate matter in the gas to be measured from the pulse signals based on a preset time window. Effective particulate matter is screened based on the consistency of the associated pulse signal time series, and particle size inversion is performed on the effective particulate matter to obtain its inverted particle size. The effective particulate matter is then divided into particle size segments based on the inverted particle size to calculate the sampling volume of each effective particulate matter in different particle size segments. The concentration of the sampled volume of the effective particulate matter in each particle size segment is calculated to obtain the particulate matter concentration in different particle size segments. Through multi-focus collaboration, effective particulate matter screening, and particle size inversion, the device effectively suppresses random noise and interference from heterogeneous particulate matter signals, improving the accuracy and reliability of particulate matter concentration measurement, thereby significantly improving the accuracy of particulate matter concentration measurement.

[0181] According to another aspect of the present invention, a measuring device is provided, such as Figure 5 As shown, it includes: a processor 401, at least one semiconductor laser diode 402, at least one convex lens 403, at least one beam splitter 404, at least two lens groups 405, a detector 406 matching the number of lens groups, and a signal processor 407.

[0182] The semiconductor laser diode 402 is used to emit a diverging laser beam toward the convex lens;

[0183] The convex lens 403 is used to convert the diverging laser beam into collimated parallel light;

[0184] The beam splitter 404 is used to split the collimated parallel light into two laser beams;

[0185] The lens group 405 is used to focus each corresponding laser beam into a focal point, and the focal points are arranged collinearly.

[0186] The detector 406 is used to generate a pulse signal based on the change in the intensity of scattered light caused by particles when particles of various sizes pass through the detection area of ​​the corresponding focal point.

[0187] The processor 401 performs the operations corresponding to the above-mentioned multi-focus collaborative particulate matter concentration measurement method;

[0188] The signal processor 407 is used to amplify the original pulse signal generated by the detector through a preamplifier to obtain an amplified original pulse signal; and to filter the amplified original pulse signal through a bandpass filter to obtain a pulse signal.

[0189] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0190] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring particulate matter concentration based on multifocal synergy, characterized in that, The method involves filling the gas to be tested into a measuring device at a preset flow rate to measure particulate matter concentration based on the measuring device. The measuring device includes at least two focal points and detectors corresponding to each focal point. The detectors are used to generate pulse signals based on the changes in the intensity of scattered light caused by the particulate matter when particulate matter of various sizes passes through the detection area of ​​the corresponding focal point. The method includes: The pulse signals generated by each detector within a preset time period are acquired, and the time series of the associated pulse signals corresponding to the particles in the gas to be tested are extracted from the pulse signals based on a preset time window. The associated pulse signals in the time series of the associated pulse signals are the pulse signals generated when the associated particles pass through each focal point in sequence. Effective particles are selected based on the consistency of the time series of the associated pulse signals of the particles, and the particle size of the effective particles is inverted to obtain the inverted particle size of the effective particles. The effective particulate matter is divided into particle size segments based on the inverted particle size, so as to calculate the sampling volume of each effective particulate matter in different particle size segments; The concentration of the effective particulate matter in each particle size range was calculated to obtain the particulate matter concentration in different particle size ranges.

2. The particulate matter concentration measurement method based on multifocal synergy according to claim 1, characterized in that, The process of extracting the time series of the associated pulse signal of any particulate matter includes: Extract the time series of pulse signals that appear within the same preset time window, wherein the preset time window is determined based on the preset flow rate and the distance between each focus; Calculate the consistency parameter between each pulse signal in the pulse signal time series, wherein the consistency parameter is the ratio of the pulse signal with the smallest voltage value to the pulse signal with the largest voltage value; If the consistency parameter is greater than or equal to the first preset consistency parameter threshold, and the timing of each pulse signal matches the order in which the same particle passes through each focal point, then the pulse signal time sequence is determined as the associated pulse signal time sequence of the particle.

3. The particulate matter concentration measurement method based on multifocal synergy according to claim 2, characterized in that, The step of filtering out effective particulate matter based on the consistency of the time series of the associated pulse signals of the particulate matter includes: If the consistency parameter of the correlated pulse signal time series is greater than or equal to the second preset consistency parameter threshold, then the particulate matter is determined as a valid particulate matter, and the signal quality of the correlated pulse signal time series is determined to be level one, wherein the second preset consistency parameter threshold is greater than the first preset consistency parameter threshold, and the signal quality is used to determine the inversion strategy for selecting the particle size; If the consistency parameter of the correlated pulse signal time series is less than the second preset consistency parameter threshold, the first time interval between every two correlated pulse signals is calculated. Based on the distance between the two focal points corresponding to the first time interval, the interfocal flight speed of the particulate matter is calculated. If the interfocal flight speed meets the flight speed verification condition, the particulate matter is determined to be a valid particulate matter, and the signal quality of the correlated pulse signal time series is determined to be level two. The signal quality of the level one correlated pulse signal time series is higher than that of the level two correlated pulse signal time series.

4. The particulate matter concentration measurement method based on multifocal synergy according to claim 3, characterized in that, The step of performing particle size inversion on the effective particulate matter to obtain the inverted particle size of the effective particulate matter includes: When the signal quality of the associated pulse signal time series is at level one, the average scattered light intensity is determined based on the mean of all associated pulse signals, and the particle size of the average scattered light intensity is matched from the pre-constructed particle size intensity calibration curve function to serve as the inversion particle size of the effective particles. When the signal quality of the associated pulse signal time series is level two, the second time interval between every two adjacent associated pulse signals is extracted, and the inverted particle size of the particles is obtained based on the second time interval, or the inverted particle size of the particles is matched from the pre-constructed particle size light intensity calibration curve function based on the associated pulse signal with the largest voltage value.

5. The particulate matter concentration measurement method based on multifocal synergy according to claim 1, characterized in that, The process of calculating the sampling volume of any effective particulate matter within any particle size range includes: Calculate the single-focal sampling volume of the effective particulate matter at any focal point, and take the average value of all single-focal sampling volumes of the effective particulate matter as the sampling volume of the effective particulate matter; Calculating the single-focus sampling volume of the effective particulate matter at any focal point specifically includes: for the associated pulse signal of the focal point, extracting the rising edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and the falling edge time point where the voltage value is equal to half the peak voltage of the pulse signal, and taking the difference between the falling edge time point and the rising edge time point as the time taken for the effective particulate matter to pass through the detection area of ​​the focal point; The target average velocity matching the current particle size range is retrieved from a pre-calibrated set of particle size range and average velocity mapping relationships. The average velocity in the set of particle size range and average velocity mapping relationships is calculated based on standard measurement values ​​of particles of different sizes within the particle size range. Based on the target average velocity of the effective particulate matter, the time taken for it to pass through the detection area of ​​the focal point, and the cross-sectional area of ​​the detection area, the single-point sampling volume of the effective particulate matter at the focal point is calculated.

6. The particulate matter concentration measurement method based on multifocal synergy according to claim 1, characterized in that, The particulate matter concentration includes particulate matter number concentration and / or particulate matter mass concentration; The calculation process for the number concentration of the particulate matter for any particle size range includes: Determine the total number of effective particles contained in the particle size range, and calculate the total sampling volume of effective particles in the particle size range; Calculate the ratio of the total number of effective particles to the total sampling volume within the particle size range to obtain the particle number concentration within the particle size range; The calculation process for the particulate matter mass concentration for any particle size range includes: The single-particle volume of the effective particulate matter is calculated based on the inverted particle size of the effective particulate matter, and the effective particulate matter density of the particle size range is retrieved. The particle mass concentration of the particle size range is calculated based on the single-particle volume, single-focus sampling volume, and effective particle density of all effective particles in the range.

7. The particulate matter concentration measurement method based on multifocal synergy according to claim 6, characterized in that, After obtaining the particulate matter mass concentration of the gas to be tested in different particle size ranges, the method further includes: The particulate matter mass concentration for any particle size range was optimized using the following method: Obtain particulate matter mass concentrations from multiple consecutive time periods preceding the current time period and signal quality levels from multiple associated pulse signal time series within each time period; For each time period, the signal quality parameters for that time period are calculated based on the number of associated pulse signal time series with different signal quality levels. Weights are assigned based on signal quality parameters for each time period to determine the weight coefficients for different time periods; The optimized particulate matter concentration for the specified particle size range is obtained by weighted summation based on the particulate matter mass concentration and weighting coefficients at different time periods.

8. The particulate matter concentration measurement method based on multifocal synergy according to claim 1, characterized in that, Before acquiring the pulse signals generated by each detector within a preset time period, the method further includes: The original pulse signal generated by the detector is amplified to obtain the amplified original pulse signal. The amplified original pulse signal is filtered to obtain a pulse signal.

9. A particulate matter concentration measurement device based on multifocal synergy, characterized in that, The device is applied to a measuring equipment, which includes at least two focal points and detectors corresponding to each focal point. The detectors are used to generate pulse signals based on the changes in the intensity of scattered light caused by particles of various sizes passing through the detection area of ​​the corresponding focal point. The device includes: The extraction module is used to acquire the pulse signals generated by each of the detectors within a preset time period, and extract the time series of the associated pulse signals corresponding to the particles in the gas to be tested from the pulse signals based on a preset time window, wherein each associated pulse signal in the time series of the associated pulse signals is the pulse signal generated when the associated particles pass through each focal point in sequence. The particle size inversion module is used to screen out effective particles based on the consistency of the time series of the associated pulse signals of the particles, and to perform particle size inversion on the effective particles to obtain the inverted particle size of the effective particles. The sampling volume calculation module is used to divide the effective particulate matter into particle size segments based on the inverted particle size, so as to calculate the sampling volume of each effective particulate matter in different particle size segments. The concentration calculation module is used to calculate the concentration of the effective particulate matter in each particle size range, so as to obtain the particle concentration in different particle size ranges.

10. A measuring device, characterized in that, include: The processor, at least one semiconductor laser diode, at least one convex lens, at least one beam splitter, at least two lens groups, a detector and a signal processor matching the number of lens groups; The semiconductor laser diode is used to emit a diverging laser beam toward the convex lens; The convex lens is used to convert the diverging laser beam into collimated parallel light; The beam splitter is used to split the collimated parallel light into two laser beams; Any of the lens groups is used to focus a corresponding laser beam into a single focal point, with the focal points arranged collinearly. The detector is used to generate pulse signals based on the changes in the intensity of scattered light caused by particles of various sizes passing through the detection area of ​​the corresponding focal point. The processor performs the operations corresponding to the particulate matter concentration measurement method based on multi-focus coordination as described in any one of claims 1-7; The signal processor is used to amplify the original pulse signal generated by the detector through a preamplifier to obtain an amplified original pulse signal. The amplified original pulse signal is filtered by a bandpass filter to obtain a pulse signal.

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