A transducer matching optimization program algorithm for NB long-distance ultrasonic gas meter

Abstract

The application relates to a transducer matching optimization program algorithm for an NB remote transmission ultrasonic gas meter, wherein the method comprises continuously sampling measurement data in the gas meter in a sampling period to obtain a sampling data set; a first sound velocity estimation value is obtained according to a forward flow propagation time and a reverse flow propagation time; a preliminary screening sub-database is obtained based on all the first sound velocity estimation values; a matching flow medium corresponding to a target flow medium is determined in the preliminary screening sub-database according to the first sound velocity estimation value; an initial working parameter group in the transducer is determined in a flow medium acoustic parameter database according to the matching flow medium; the initial working parameter group is adaptively corrected according to the first sound velocity estimation value to obtain a recommended working parameter group; a control instruction is generated based on the recommended working parameter group, and the control instruction is sent to the transducer. Compared with a fixed gain mode, the method can adaptively match various gas media, and the application range of the ultrasonic gas meter is significantly expanded.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of transducer matching optimization, in particular to a transducer matching optimization program algorithm for an NB remote transmission ultrasonic gas meter. BACKGROUND

[0002] In the technical field of gas meters, traditional diaphragm gas meters have long dominated the market and are widely used. However, diaphragm gas meters have many inherent drawbacks that are difficult to overcome. The structure of diaphragm gas meters is complex and includes many mechanical components that inevitably wear out during continuous operation. As the length of use increases, wear accumulates, causing the measurement accuracy of the gas meter to gradually deteriorate, making it impossible to accurately measure gas flow and causing large errors and uncertainties in gas metering work.

[0003] With the progress and development of science and technology, ultrasonic gas meters have emerged as a new type of measuring instrument. Ultrasonic gas meters are pure digital measuring devices with many outstanding features. They have stable performance and are not affected by problems such as wear of traditional mechanical components, allowing them to maintain a stable operating state for a long time. In terms of remote meter reading, ultrasonic gas meters have the advantages of safety and efficiency, and can easily achieve remote data acquisition and monitoring through digital signal transmission, greatly improving the intelligent level of gas management. At the same time, their measurement accuracy is reliable, and compared to traditional diaphragm gas meters, they can more accurately measure the amount of gas used, providing more accurate data support for gas trade settlement. Moreover, ultrasonic gas meters are easy to digitize and can be easily integrated with modern intelligent gas management systems, meeting the needs of digital gas metering and management in the digital age, and thus becoming an inevitable trend in the development of gas meter technology.

[0004] However, despite the many advantages of ultrasonic gas meters, they still face some challenges in practical applications. Some existing ultrasonic gas meters are equipped with gain control circuits, but their gain values are set in a fixed mode. Different gas media have different physical properties, such as density and sound speed. A fixed gain value can only achieve relatively accurate flow measurement for a specific measured medium, and when other types of gas media are encountered, the measurement accuracy will be greatly reduced, making it difficult to meet the general needs of multiple gas media measurement. SUMMARY

[0005] To solve the above technical problems, the application provides a transducer matching optimization program algorithm for an NB remote transmission ultrasonic gas meter.

[0006] In a first aspect, the application provides a transducer matching optimization program algorithm for an NB remote transmission ultrasonic gas meter, which adopts the following technical solution:

[0007] A transducer matching optimization program algorithm for NB long-distance ultrasonic gas meter, comprising:

[0008] After the target flow in the target pipeline flows for a period of time, the measurement data in the gas meter is continuously sampled in a preset sampling period to obtain a sampling data set, the sampling period includes a plurality of sampling sub-periods, and the sampling data set includes the downstream propagation time and the upstream propagation time of ultrasonic waves in the target flow;

[0009] According to the downstream propagation time and the upstream propagation time corresponding to each sampling sub-period, a first sound speed estimation value of ultrasonic waves in the target flow is obtained, and the first sound speed estimation value corresponds to the sampling sub-period one by one;

[0010] Based on all the first sound speed estimation values, preliminary screening is performed in a preset flow acoustic parameter database to obtain a preliminary screening sub-database;

[0011] According to the first sound speed estimation value in the preliminary screening sub-database, a matching flow corresponding to the target flow is determined;

[0012] According to the matching flow, an initial working parameter group in the transducer is determined in the flow acoustic parameter database;

[0013] According to all the first sound speed estimation values, the initial working parameter group is adaptively corrected to obtain a recommended working parameter group;

[0014] Based on the recommended working parameter group, a control instruction is generated and sent to the transducer to replace the current working parameter group in the transducer with the recommended working parameter group.

[0015] In a specific implementation scheme, the flow acoustic parameter database includes an acoustic parameter group corresponding to each known type of flow one by one, and the acoustic parameter group includes a standard sound speed of ultrasonic waves in the corresponding flow under a preset standard working environment and a plurality of comparison sound speeds of ultrasonic waves in the corresponding flow under a plurality of preset specific environments, the specific environment corresponding to the comparison sound speed one by one; the preliminary screening based on all the first sound speed estimation values in the preset flow acoustic parameter database to obtain a preliminary screening sub-database includes:

[0016] Based on all the first sound speed estimation values, a sound speed approximation value corresponding to the sampling period is obtained, and the sound speed approximation value is used to reflect the actual sound speed of ultrasonic waves in the target flow;

[0017] The sound speed approximation value is input into a preset reference range calculation formula to obtain a reference sound speed interval corresponding to the target flow;

[0018] Each of the standard sound speeds is compared with the reference sound speed range to determine whether the standard sound speed is within the reference sound speed range;

[0019] When the standard sound velocity is within the reference sound velocity range, the fluid corresponding to the standard sound velocity is used as the candidate fluid, and all the candidate fluids are used as the initial screening database.

[0020] In a specific feasible implementation, the formula for calculating the reference range is as follows:

[0021] ;

[0022] in, This represents the approximate sound velocity of the ultrasonic signal in the target fluid during the sampling period; Indicates the reference sound speed range. This represents the minimum sound speed value within the reference sound speed range. This represents the maximum sound speed value within the reference sound speed range; This indicates the standard temperature corresponding to a specific target environment. This represents the standard pressure corresponding to the specific environment of the target; This indicates the current actual temperature of the target pipeline; This indicates the current actual pressure of the target pipeline; For correction coefficients and ; as well as represents the formula fitting coefficient, and represents the constant term.

[0023] In one specific implementation, obtaining the approximate sound velocity value corresponding to the sampling time period based on all the first sound velocity estimates includes:

[0024] The second sound speed estimate is calculated based on the downstream propagation time and the upstream propagation time. The formula for calculating the second sound speed estimate is as follows:

[0025] ;

[0026] in, Indicates the relationship with the first The second velocity of sound estimate corresponding to the sampling sub-period; Indicates the propagation path of the ultrasound signal; Indicates the relationship with the first The downstream propagation time corresponding to the sampling sub-period; Indicates the relationship with the first The backflow propagation time corresponding to the sampling sub-period;

[0027] verifying the first sound speed estimation value according to the second sound speed estimation value to obtain a verification result, the verification result including that the first sound speed estimation value has a smaller error and that the first sound speed estimation value has a larger error;

[0028] when the verification result is that the first sound speed estimation value has a smaller error, directly taking the average value of all the first sound speed estimation values as a sound speed approximation value;

[0029] when the verification result is that the first sound speed estimation value has a larger error, obtaining a sound speed approximation value according to the first sound speed estimation value and the second sound speed estimation value.

[0030] In one specific implementation, the determining a matching fluid corresponding to the target fluid in the preliminary screening database according to the first sound speed estimation value includes:

[0031] obtaining an actual temperature and an actual pressure in the target pipeline, and matching a target specific environment according to the actual temperature and the actual pressure, taking the temperature corresponding to the target specific environment as a standard temperature and taking the pressure corresponding to the target specific environment as a standard pressure, the target specific environment being one of the specific environments in the fluid acoustic parameter database;

[0032] obtaining a comprehensive difference index according to the actual temperature, the actual pressure, the standard temperature and the standard pressure;

[0033] obtaining a matching degree corresponding to each type of fluid based on the comprehensive difference index, the contrast sound speed and the sound speed approximation value;

[0034] determining a matching fluid according to the matching degree.

[0035] In one specific implementation, the comprehensive difference index is calculated as follows:

[0036] ;

[0037] ;

[0038] ;

[0039] wherein, is the comprehensive difference index; respectively are preset temperature and pressure weight coefficients; represents the actual temperature in the pipeline; represents the actual pressure in the target pipeline; represents the standard temperature corresponding to the target specific environment; represents the standard pressure corresponding to the target specific environment;

[0040] The formula for calculating the degree of matching is as follows:

[0041] ;

[0042] ;

[0043] ;

[0044] in, Indicates the speed of sound relative to the specific environment of the target; This represents an approximate value of the current speed of sound. This represents the maximum possible difference in sound speed as preset; C represents the quantized value of the sound speed difference. Indicates the degree of matching.

[0045] In one specific implementation scheme, the initial operating parameter set includes the initial transmit power and initial impedance matching value of the transducer, and the fluid acoustic parameter database also includes several initial operating parameters corresponding to each type of fluid; the adaptive correction of each initial operating parameter based on the approximate sound velocity corresponding to all sampling sub-time periods yields the following calculation formula in the recommended operating parameter set:

[0046] ;

[0047] ;

[0048] ;

[0049] in, Indicates the relationship with the first Approximate sound velocity corresponding to each sampling sub-period; This represents the average value of the approximate sound velocity over the entire sampling period; This represents the standard velocity of sound corresponding to the matched fluid. This indicates the total number of sampling sub-time periods within the sampling period; This represents the actual speed of sound used to represent the propagation of the matched fluid within the pipe; This is the initial transmit power. To correct the transmission power, that is, the transmission power obtained after correcting the initial transmission power; To correct the impedance matching value; This is the initial impedance matching value; Indicates the first Each sampling sub-period; This indicates the fluid density corresponding to the matched fluid.

[0050] Secondly, this application provides a smart terminal, which adopts the following technical solution:

[0051] An intelligent terminal comprises a memory and a processor, the memory storing at least one instruction, at least one program, a code set or an instruction set, the at least one instruction, at least one program, code set or instruction set being loaded and executed by the processor to implement the transducer matching optimization program algorithm for NB remote transmission ultrasonic gas meter as described in the first aspect.

[0052] In a third aspect, the application provides a computer-readable storage medium, which adopts the technical scheme as follows:

[0053] A computer-readable storage medium, the readable storage medium storing at least one instruction, at least one program, a code set or an instruction set, the at least one instruction, at least one program, code set or instruction set being loaded and executed by a processor to implement the transducer matching optimization program algorithm for NB remote transmission ultrasonic gas meter as described in the first aspect.

[0054] In summary, the application includes at least one of the following beneficial technical effects:

[0055] 1. The application obtains sound velocity data of different time periods through continuous sampling, and combines the screening and matching of the liquid acoustic parameter database to identify the physical characteristic differences (such as density and sound velocity) of the target liquid in real time, thereby dynamically adjusting the transducer parameters; compared with the fixed gain mode, the method can adaptively match natural gas, liquefied gas and other gas media, significantly expanding the application range of the ultrasonic gas meter;

[0056] 2. The application introduces the difference calculation (comprehensive difference index) of actual temperature, pressure and standard environmental parameters, and combines the fusion algorithm of sound velocity approximation value to effectively compensate the influence of environmental changes on sound velocity. By adaptively correcting the initial working parameter set (such as transmission power and impedance matching value), the transducer output is ensured to be optimally matched with the current liquid and working condition, and the accuracy of flow measurement is improved;

[0057] 3. A two-stage screening strategy (preliminary screening sub-database construction and matching degree quantification) is adopted to quickly lock the matching liquid based on the sound velocity approximation value and environmental parameters. This method quantifies the similarity of liquids through mathematical modeling (such as the matching degree formula), effectively avoiding the time loss of the traditional trial-and-error method, improving the matching efficiency, and being especially suitable for scenarios where the composition of gas frequently fluctuates;

[0058] 4. Through cross-validation of multi-period sampling data (using the second sound velocity estimation value to verify the first sound velocity estimation value, and combining the two to obtain a more accurate sound velocity approximation value), transient noise interference is effectively filtered out, and combined with the dynamic updating mechanism of the recommended working parameter set, the performance drift caused by transducer aging or medium deposition can be suppressed, greatly extending the calibration period of the gas meter. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 is a flowchart of a transducer matching optimization program algorithm for NB remote ultrasonic gas meters according to an embodiment of the present application. DETAILED DESCRIPTION

[0060] To make the purposes, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0061] The embodiments of the transducer matching optimization program algorithm for NB remote ultrasonic gas meters according to the present application will be further described in detail below with reference to the drawings.

[0062] An embodiment of the present application discloses a transducer matching optimization program algorithm for NB remote ultrasonic gas meters.

[0063] Reference Figure 1 A transducer matching optimization program algorithm for NB remote ultrasonic gas meters includes:

[0064] S100, after a target fluid in a target pipeline flows for a period of time, continuously sampling measurement data in a gas meter in a preset sampling period to obtain a sampling data set;

[0065] Wherein, the target pipeline refers to a pipeline currently installed with an ultrasonic gas meter, the target fluid refers to a certain gaseous substance flowing in the target pipeline, such as natural gas, coal gas or gasified gas of liquefied petroleum gas, etc. Common gas types; the measurement data refers to the ultrasonic time of flight data (i.e. the downstream propagation time and the upstream propagation time in the following) calculated by the ultrasonic transducer according to the ultrasonic signals transmitted and received; the sampling period refers to the total time of continuous sampling, including a plurality of sampling sub-periods with equal time length, the sampling period of the present embodiment is 2 minutes, and the sampling sub-period is taken as 10 seconds for example, so as to ensure that there is enough sampling data for analysis, and the amount of sampling data is not too large to cause low analysis and calculation efficiency; the sampling data set includes the downstream propagation time and the upstream propagation time of the ultrasonic wave in the target fluid in each sampling sub-period.

[0066] It needs to be particularly pointed out that the ultrasonic gas meter in the embodiment does not need to be artificially calibrated before leaving the factory to adapt the ultrasonic gas meter to the specific flow measurement of the flow medium, so when the gas meter is first applied to the flow measurement of the target flow medium in the target pipeline, it is necessary to first perform self-adaptive debugging according to the sampling data set obtained in the sampling period to complete automatic matching optimization; at the beginning of each sampling sub-period in the sampling period, the main control board in the gas meter sends an electric signal to one of the transducers, the transducer receiving the electric signal emits an ultrasonic signal to the other transducer, and the other transducer feeds back the received ultrasonic signal after receiving the ultrasonic signal; when the transducer originally emitting the ultrasonic signal receives the feedback ultrasonic signal, it sends an electric signal to the main control board; a time stamp is recorded in the main control board when each transducer receives / emits the ultrasonic signal and the main control board actively emits / passively receives the electric signal, and the main control board calculates the corresponding downstream propagation time and upstream propagation time of the ultrasonic wave in each sampling sub-period according to the time stamps, the downstream propagation time refers to the difference between the time point at which one transducer emits the ultrasonic signal and the time point at which the other transducer receives the ultrasonic signal; the upstream propagation time refers to the difference between the time point at which the other transducer feeds back the ultrasonic signal and the time point at which the original transducer receives the feedback ultrasonic signal.

[0067] S200, obtaining a first speed estimation value of the ultrasonic wave in the target flow medium according to the downstream propagation time and the upstream propagation time corresponding to each sampling sub-period;

[0068] The first speed estimation value corresponds to the sampling sub-period one by one; specifically, S200 includes:

[0069] S210, obtaining a preset installation parameter in the main control board;

[0070] The installation parameter includes an ultrasonic signal propagation path, a transducer installation cavity path, a horizontal angle between the ultrasonic path and the target pipeline, and an energy conversion delay time;

[0071] It needs to be particularly pointed out that the ultrasonic signal propagation path refers to the actual total path length of the ultrasonic signal in the target flow medium between the two transducers, which can be obtained by directly measuring the distance between the two transducer installation points on the target pipeline; for a straight pipeline, if the two transducers are installed at the two ends of the diameter of the pipeline, the ultrasonic signal propagation path is the diameter of the pipeline, which can be directly measured using a caliper, a laser range finder or the like; for a non-straight or complex-shaped pipeline, the theoretical path length of the ultrasonic signal propagation can be calculated as the ultrasonic signal propagation path according to the design drawings of the pipeline and the use of geometric knowledge, or the path length can be calculated by using trigonometric functions and other mathematical methods according to the known pipeline size parameters and transducer installation angles and other information;

[0072] The transducer installation cavity path refers to the actual path of the ultrasonic signal in the cavity when the transducer is installed in the cavity (housing), i.e., the ultrasonic signal emitted by the transducer will first pass through the propagation path in the installation cavity and then enter the target pipeline; usually, this value is directly obtained according to the preset design size and shape when the transducer installation cavity of the gas meter is produced;

[0073] The energy conversion delay time refers to the time delay experienced in the process of converting an electrical signal into an ultrasonic signal or converting an ultrasonic signal into an electrical signal.

[0074] S220, constructing a propagation time-acoustic velocity relationship equation set according to the installation parameters, and obtaining a first acoustic velocity estimation value corresponding to each sampling sub-period according to the propagation time-acoustic velocity relationship equation set;

[0075] The first acoustic velocity estimation value is obtained by solving the propagation time-acoustic velocity relationship equation set; the propagation time-acoustic velocity relationship equation set of the embodiment is as follows:

[0076]

[0077] After solving, the calculation formula of the first acoustic velocity estimation value is as follows:

[0078]

[0079] wherein, represents the downstream propagation time corresponding to the first sampling sub-period; represents the upstream propagation time corresponding to the first sampling sub-period; represents the upstream propagation time corresponding to the first sampling sub-period; represents the ultrasonic signal propagation path; represents the flow velocity of the target fluid, which is a preset value; represents the transducer installation cavity path; represents the energy conversion delay time; represents the first acoustic velocity estimation value corresponding to the first sampling sub-period; represents the horizontal angle between the ultrasonic path and the target pipeline. S300, performing preliminary screening in a preset fluid acoustic parameter database based on all the first acoustic velocity estimation values, to obtain a preliminary screening sub-database;

[0080] S300, performing preliminary screening in a preset fluid acoustic parameter database based on all the first acoustic velocity estimation values, to obtain a preliminary screening sub-database;

[0081] ​​​The fluid acoustic parameter database includes a set of acoustic parameters corresponding to each known fluid. Each set of acoustic parameters includes the standard sound velocity of ultrasound in the corresponding fluid under standard operating conditions and the comparative sound velocity of ultrasound in the corresponding fluid under several specific conditions. The fluid acoustic parameter database of this embodiment is shown in Table 1 below:

[0082] Table 1:

[0083]

[0084] It should be noted that in step S300, this embodiment mainly determines the specific type of the target fluid by using the fluid acoustic parameter database and the first sound velocity estimate obtained in S200. That is, when the sound velocity data of a certain fluid in the fluid acoustic parameter database and the sound velocity data of the target fluid meet a certain similarity condition (such as the similarity of the sound velocity value / sound velocity change curve with temperature or pressure reaching 95%), the target fluid is regarded as the fluid of that type. In this process, in order to effectively ensure the accuracy and efficiency of matching fluids corresponding to the target fluid, this embodiment first uses the standard sound velocity and the actual sound velocity data of the target fluid (i.e., the first sound velocity estimate and the sound velocity approximation in S340) to screen out several candidate fluids with similar attributes (i.e., similar sound velocity data) in the fluid acoustic parameter database. The above screening method does not require more complex characteristic analysis and matching calculation, which greatly reduces the amount of calculation and can provide a high-quality candidate set for determining the matching fluid in S400, effectively ensuring the accuracy when determining the matching fluid.

[0085] Therefore, it is evident that the rationality of the screening conditions (i.e., the reference sound velocity range in S360) greatly affects the accuracy of the determination of the target fluid type. Thus, this embodiment employs the following method to minimize errors in the screening conditions. Specifically, S300 includes:

[0086] S310, calculate the second speed of sound estimate based on the downstream propagation time and the upstream propagation time;

[0087] The formula for calculating the second sound speed estimate is as follows:

[0088] ;

[0089] in, Indicates the relationship with the first The second velocity of sound estimate corresponding to the sampling sub-period; Indicates the propagation path of the ultrasound signal; Indicates the relationship with the first The downstream propagation time corresponding to the sampling sub-period; Indicates the relationship with the first The reverse flow propagation time corresponding to the sampling time interval.

[0090] S320, verifying the first speed estimation value according to the second speed estimation value to obtain a verification result;

[0091] The verification result includes that the first speed estimation value has a large error and that the first speed estimation value has a small error. Specifically, S320 includes:

[0092] S321, calculating a difference degree between the first speed estimation value and the second speed estimation value.

[0093] The difference degree calculation formula is as follows:

[0094] ;

[0095] ;

[0096] ;

[0097] wherein, represents the second average speed of the ultrasonic signal in the target fluid in the sampling time interval; represents the first speed estimation value corresponding to the sampling time interval; represents the second speed estimation value corresponding to the sampling time interval; represents the first average speed of the ultrasonic signal in the target fluid in the sampling time interval; represents the first speed estimation value corresponding to the sampling time interval; represents the second speed estimation value corresponding to the sampling time interval; represents the difference degree, which reflects the difference degree between the first speed estimation value and the second speed estimation value obtained by the two calculation methods.

[0098] It should be particularly noted that the first speed estimation value and the second speed estimation value obtained by the two calculation methods mentioned above respectively refer to a plurality of first speed estimation values (i.e. theoretical values) calculated by combining the target pipeline installation characteristics through the propagation time-speed relationship equation set in step S220, and a plurality of second speed estimation values (i.e. actual values) directly obtained through step S310. .

[0099] S322, comparing the difference degree with a preset difference threshold;

[0100] In this embodiment, the difference threshold is taken as an example.

[0101] S323, if the difference is greater than the difference threshold, a verification result that the first sound speed estimation value has a large error is obtained; otherwise, a verification result that the first sound speed estimation value has a small error is obtained.

[0102] S330, when the verification result is that the first sound speed estimation value has a small error, the average value of the first sound speed estimation value is directly taken as the sound speed approximation value.

[0103] It should be particularly pointed out that the core purpose of the matching optimization method for the transducer provided in the embodiment is to enable the ultrasonic gas meter of a unified model to have excellent adaptive capability. This adaptation is manifested in that, without the need for special design and artificial calibration for a specific flow, the ultrasonic gas meter can automatically match a precise flow metering mode according to the target flow; this also means that the ultrasonic gas meter applying the matching optimization method of the embodiment often uses a unified hardware configuration (temperature sensor, pressure sensor, and other key components). Since the pressure and temperature conditions of the same hardware configuration are usually not significantly different, for example, the gas meters used in high-temperature or high-pressure scenarios are uniformly equipped with specific hardware configurations that are resistant to high temperature and high pressure, while the gas meters in ordinary working conditions are uniformly equipped with conventional hardware configurations. Based on this, in the subsequent S340 step of the embodiment, there is no need to consider the problem that a large error in the first sound speed estimation value is caused by a large deviation between the actual temperature / actual pressure and the corresponding standard temperature / standard pressure, and thus the embodiment further includes the following steps when correcting the first sound speed estimation value with a large error:

[0104] S340, when the verification result is that the first sound speed estimation value has a large error, a sound speed approximation value is obtained according to the first sound speed estimation value and the second sound speed estimation value;

[0105] Specifically, S340 includes:

[0106] S341, a sound speed variation equation is determined;

[0107] The sound speed variation equation is used to reflect a certain regular variation of the sound speed between adjacent sampling sub-periods. Specifically, the sound speed variation equation is as follows:

[0108] ;

[0109] wherein, represents the sound speed approximation value corresponding to the first sampling sub-period, represents the sound speed approximation value corresponding to the second sampling sub-period; is the process noise in ultrasonic propagation, which is used to represent the random variation of the sound speed approximation value due to various unconfirmed factors; denotes a state transition matrix, in the embodiment, , for indicating that there is no obvious systematic change trend of the sound speed approximation value in the process from the first sub-period to the second sub-period.

[0110] S342, constructing a sound speed prediction equation based on the first average sound speed and the second average sound speed;

[0111] wherein the sound speed prediction equation is used to predict the sound speed approximation value of the next sub-period according to the sound speed approximation value of the last sub-period; specifically, the sound speed prediction equation is as follows:

[0112] ;

[0113] ;

[0114] wherein, denotes a sound speed prediction value; denotes a sound speed approximation value corresponding to the first sub-period, denotes a transpose matrix of the vector ; is an observation matrix, in the embodiment, ; denotes observation noise in ultrasonic wave propagation.

[0115] S343, respectively determining a process noise covariance matrix corresponding to the process noise and an observation noise covariance matrix corresponding to the observation noise;

[0116] wherein the observation noise covariance matrix is used to describe the characteristics and the correlation between the noises generated by the two sound speed calculation methods (corresponding to the calculation methods of the first average sound speed and the second average sound speed) in the sound speed prediction process; the process noise covariance matrix is used to represent the covariance situation of the random change of the sound speed approximation value due to various uncertain factors; generally, the value of the observation noise covariance matrix can be determined in advance through a large amount of experimental data: analyze the deviation of each measurement result of the two sound speed calculation methods from the true value under different measurement environments and different flow conditions, and statistically analyze the variance and other information of these deviation data to construct the observation noise covariance matrix; and for the process noise covariance matrix, the element values thereof can be determined according to the statistical data of the fluctuation degree of the sound speed under similar working conditions when the sound speed changes over time or other interference factors; in the embodiment, the two sound speed calculation methods are independent of each other, so the observation noise covariance matrix is a diagonal matrix, and the elements on the diagonal correspond to the variances between all observation noises obtained by the two methods, respectively. The above determination method is prior art, and will not be described here.

[0117] S344, initialize the sound speed approximation and the covariance matrix corresponding to the sound speed approximation;

[0118] wherein, at the initial time (i.e. at the beginning of the first sampling sub-period), an initial estimation of the sound speed approximation is needed, and in the embodiment, the sound speed approximation takes the average of the first sound speed estimation and the second sound speed estimation at the initial time; the covariance matrix corresponding to the sound speed approximation is used to represent the uncertainty of the initial estimated sound speed approximation, and the value of the covariance matrix can be set according to the reliability of the initial estimation, if the initial estimation is more accurate, the value is smaller, and vice versa, in the embodiment, the covariance matrix corresponding to the sound speed approximation is taken as a diagonal matrix, and the elements on the diagonal line take the variance between all sound speed approximations.

[0119] S345, starting from the initial state, gradually advancing to each subsequent sampling sub-period to continuously optimize the estimation of the sound speed approximation, and obtaining the final sound speed approximation;

[0120] Specifically, S345 includes:

[0121] S3451, at the beginning of each new sampling sub-period, predicting the sound speed approximation of the current sampling sub-period based on the sound speed approximation obtained in the previous sampling sub-period and the sound speed change equation in S341;

[0122] wherein, S3451 assumes that there is no obvious systematic change trend between adjacent sampling sub-periods, and only a simple continuation is made according to the state transition matrix in S341 on the basis of the original.

[0123] S3452, constantly updating the covariance matrix corresponding to the sound speed approximation through a preset covariance update equation;

[0124] wherein, the covariance update equation is as follows:

[0125]

[0126] wherein, represents the covariance matrix of the sound speed approximation corresponding to the kth sampling sub-period, and is used to reflect the uncertainty degree of the predicted sound speed approximation corresponding to the kth sampling sub-period after considering the uncertainty propagation of the (k-1)th sampling sub-period and the influence of the new process noise; represents the covariance matrix of the sound speed approximation corresponding to the (k-1)th sampling sub-period; represents the state transition matrix; represents the transpose matrix of the state transition matrix; represents the process noise covariance matrix. ​

[0127] S3453, determining a Kalman gain, and correcting the newly obtained sound speed approximation value according to the Kalman gain to obtain a final sound speed approximation value;

[0128] The formula for calculating the Kalman gain is as follows:

[0129]

[0130] , wherein, represents the Kalman gain; represents a covariance matrix of the sound speed approximation value corresponding to the kth sub-time interval; represents an observation matrix, which is used to establish a relationship between the sound speed approximation value corresponding to the last sub-time interval and the sound speed approximation value corresponding to the next sub-time interval; represents a transpose matrix of the observation matrix; represents an observation noise covariance matrix;

[0131] The formula for correcting the sound speed approximation value is as follows:

[0132]

[0133] , wherein, represents the sound speed approximation value corresponding to the kth sub-time interval; represents the sound speed prediction value corresponding to the kth sub-time interval; represents the sound speed prediction value corresponding to the kth sub-time interval; represents the Kalman gain; represents an observation noise in ultrasonic wave propagation; represents an observation matrix; represents a residual error between the observation data and the prediction data, which is used to reflect the difference between the observation data and the prediction result, adjusts the prediction according to the residual error value , so as to obtain a more accurate sound speed approximation value corresponding to the kth sub-time interval. It should be particularly noted that the steps S3451-S3452 above are mainly time update steps, which are used to predict the sound speed approximation value; and the step S3453 is mainly a measurement update step, which is used to continuously correct the predicted sound speed approximation value. In this way, the sound speed approximation value and its uncertainty are optimized at each sub-time interval by repeatedly performing the above time update and measurement update steps. With the iteration, the sound speed approximation value gradually approaches the true value, so as to realize effective fusion of the results of the two sound speed calculation methods, obtain a more accurate sound speed approximation value, and meet the needs of subsequent applications.

[0134] It should be particularly noted that the steps S3451-S3452 above are mainly time update steps, which are used to predict the sound speed approximation value; and the step S3453 is mainly a measurement update step, which is used to continuously correct the predicted sound speed approximation value. In this way, the sound speed approximation value and its uncertainty are optimized at each sub-time interval by repeatedly performing the above time update and measurement update steps. With the iteration, the sound speed approximation value gradually approaches the true value, so as to realize effective fusion of the results of the two sound speed calculation methods, obtain a more accurate sound speed approximation value, and meet the needs of subsequent applications.

[0135] ​​​S350, input the sound speed approximation value into a preset reference range calculation formula to obtain a reference sound speed interval corresponding to the target fluid;

[0136] The reference range calculation formula is as follows:

[0137]

[0138] denotes an approximate value of the sound speed of the ultrasonic signal in the target fluid in the sampling period; denotes a reference sound speed interval, used for screening candidate fluids, denotes a minimum sound speed value in the reference sound speed interval, denotes a maximum sound speed value in the reference sound speed interval; denotes a standard temperature in a standard environment, which is taken as 20℃ in this embodiment; denotes a standard pressure in a standard environment, which is taken as 1 atm in this embodiment; denotes a current actual temperature of the target pipeline, which is obtained by a temperature sensor installed in the target pipeline; denotes a current actual pressure of the target pipeline, which is obtained by a pressure sensor installed in the target pipeline; denotes a correction coefficient related to the characteristics of the fluid, and Generally speaking, the greater the reference sound speed interval is, the fewer the number of candidate fluids obtained in the subsequent step S370 is, and in order to reduce the amount of calculation while effectively ensuring the accuracy of screening candidate fluids in S370 and determining matching fluids in S400; and is a formula fitting coefficient, which is mainly obtained by analyzing and fitting a large amount of experimental data, and is used for accurately adjusting the calculation of the reference sound speed interval, wherein directly affects the constant term part in the formula, and is associated with the correction coefficient, and together determines the adjustment range of the reference sound speed interval with and temperature and pressure.

[0139] In this embodiment, and are both taken as 1 according to experimental data, is also determined by fitting a large amount of experimental data on the sound speed of the target fluid under different temperature and pressure conditions, and is determined as 0.8 after repeated testing and optimization in this embodiment, 0.3, the selection of this set of values ensures that as increases, the reference sound speed interval ​​The limited range can be reduced to a certain extent as expected, while maintaining the accurate reflection of the target fluid sound speed characteristics within the common temperature and pressure fluctuation range.

[0140] It should be noted that due to the change of the characteristics of the target fluid in different application scenarios, for example, when a small amount of impurities is mixed in the target fluid, although the influence of temperature and pressure on sound speed still follows the above formula, the correction coefficient Reflecting the connotation will be different, at this time, the value of Need to be re-evaluated and calibrated to ensure the accuracy of the reference sound speed interval calculation; specifically, The value can be dynamically adjusted by periodically calibrating the system, collecting actual time data of ultrasonic wave transmission under different working conditions, and using data fitting and error analysis methods, so that the system always maintains the best operating state, provides more reliable reference sound speed interval data for S360 and S400 steps, and further improves the performance and stability of the entire fluid identification and matching system.

[0141] S360, compare the standard sound speed corresponding to each type of fluid with the reference sound speed interval obtained from the first sound speed estimate value to determine whether the standard sound speed is within the reference sound speed interval.

[0142] S370, when the standard sound speed is within the reference sound speed interval, the fluid corresponding to the standard sound speed is selected as the candidate fluid, and all candidate fluids are selected as the preliminary screening database;

[0143] Among them, the candidate fluid refers to the fluid whose sound speed characteristics are more consistent with the sound speed characteristics of the target fluid.

[0144] S400, determine the matching fluid corresponding to the target fluid in the preliminary screening database according to the first sound speed estimate value;

[0145] Among them, the matching fluid refers to the fluid that is most likely to be of the same type as the target fluid, which is a candidate fluid in the preliminary screening database; specifically, in combination with the above S310-S370, S400 mainly refers to obtaining the matching fluid in the preliminary screening database based on the standard sound speed, the contrast sound speed and the sound speed approximation value obtained from all first sound speed estimate values, including the following steps:

[0146] S410, match the target specific environment that best matches the actual temperature and actual pressure in the current pipeline, and take the temperature corresponding to the target specific environment as the standard temperature and the pressure as the standard pressure;

[0147] Wherein, for each specific environment in the preliminary screening sub-database, the degree of difference between it and the current actual temperature and actual pressure is calculated. For example, the absolute value of the temperature difference and the absolute value of the pressure difference can be calculated respectively, and then the two difference values are combined into one comprehensive difference index according to a certain weighting method. By comparing the comprehensive difference indexes of each specific environment, the specific environment with the smallest comprehensive difference is selected as the target specific environment, so as to determine the corresponding standard temperature and standard pressure; specifically, the calculation method of the comprehensive difference index is as follows:

[0148] ;

[0149] ;

[0150] ;

[0151] Wherein, is the comprehensive difference index; respectively, the pre-set temperature and pressure weight coefficients, both of which are taken as 0.5 in the embodiment; represents the actual temperature in the pipeline; represents the actual pressure in the pipeline; represents the standard temperature corresponding to the target specific environment; represents the standard pressure under the target specific environment.

[0152] S420, based on the comprehensive difference index, the comparison sound speed corresponding to the target specific environment and the sound speed approximation value, the matching degree corresponding to each type of flow is obtained;

[0153] Wherein, the calculation formula of the matching degree is as follows:

[0154] ;

[0155] ;

[0156] ;

[0157] Wherein, represents the comparison sound speed corresponding to the target specific environment; represents the current sound speed approximation value; represents the pre-set maximum possible difference of the sound speed, which is taken as 2m / s in the embodiment; C represents the quantization value of the sound speed difference; represents the matching degree, when C or is larger, it means that the target flow and the corresponding candidate flow are more different, and at this time the matching degree is smaller.

[0158] S430, determining the matching flow according to the matching degree;

[0159] Among them, the matching degree of all kinds of fluids is sorted, and the fluid with the highest matching degree and greater than the preset matching threshold is selected as the matching fluid. The matching threshold of the embodiment is taken as an example.

[0160] S500, determining the initial working parameter group of the transducer according to the matching fluid in the fluid acoustic parameter database;

[0161] Among them, the fluid acoustic parameter database further includes a plurality of initial working parameters corresponding to each kind of fluid, and the initial working parameter group includes three initial working parameters of the initial transmitting power, the initial impedance matching value and the initial bandwidth of the transducer; each initial working parameter in the initial working parameter group is a set of parameter values set based on theoretical analysis, experimental data and past experience before ultrasonic measurement of a certain specific fluid, so that the transducer can initially achieve good performance under the transmission of the fluid, and the standard sound velocity corresponding to different kinds of fluids in this process is measured under specific temperature, pressure and fluid purity standard environmental conditions, which represents the acoustic characteristics of the corresponding kind of fluid in an ideal and stable state.

[0162] Specifically, the initial working parameter of the transmitting power needs to consider the absorption characteristics of different fluids to ultrasonic signals, the required distance range of measurement, and the power bearing capacity of the transducer itself and other factors; for fluids with high absorption coefficient, such as some impure or high-viscosity gases, a relatively high transmitting power is usually set to ensure that the ultrasonic signal can maintain sufficient strength during transmission and carry complete and effective measurement information to the receiving end (another transducer); and for relatively pure and small sound attenuation fluids, the transmitting power can be appropriately reduced to avoid signal distortion, transducer overheating and other problems caused by excessive power, while also helping to prolong the service life of the transducer and reduce power consumption.

[0163] The initial working parameter of the impedance matching value needs to consider the acoustic impedance characteristics of the fluid and the equivalent acoustic impedance of the transducer. By accurately measuring or estimating the parameters such as density and sound velocity of the fluid, the acoustic impedance is calculated, and then appropriate circuit elements (such as inductors, capacitors, etc.) are selected to combine the input impedance of the transducer and the acoustic impedance of the fluid as close as possible, so as to realize efficient transmission of ultrasonic energy between the transducer and the fluid, reduce reflection loss, and improve the transmission efficiency of the signal and the accuracy of the measurement.

[0164] The initial operating parameters of the bandwidth need to comprehensively consider factors such as the potential range of sound velocity variations in the fluid and the required accuracy of the acoustic characteristics to be measured. If the fluid composition is complex or the sound velocity may fluctuate significantly due to factors such as temperature and pressure during the measurement process, a wider bandwidth needs to be set to ensure that the transducer can effectively receive and process ultrasonic signals containing different frequency components, avoiding the loss of important measurement information due to insufficient bandwidth. Conversely, if the fluid characteristics are relatively stable and the measurement requirements are not high in frequency resolution, appropriately reducing the bandwidth can improve the signal-to-noise ratio, reduce unnecessary noise interference, and enhance the stability and reliability of the measurement signal.

[0165] S600, based on all the first sound velocity estimates, adaptively corrects the initial working parameter set to obtain the recommended working parameter set;

[0166] Specifically, S600 mainly refers to adaptive correction of each initial working parameter in the initial working parameter group based on the approximate sound velocity value corresponding to all sampling sub-time periods;

[0167] In this embodiment, the adjustment of each initial operating parameter is mainly achieved through the following methods:

[0168] Regarding the transmission power, considering the linear relationship between the approximate sound speed and the transmission power, the adaptive correction formula for the initial transmission power in this embodiment is as follows:

[0169] ;

[0170] ;

[0171] in, Indicates the relationship with the first Approximate sound velocity corresponding to each sampling sub-period; This represents the average value of the approximate sound velocity over the entire sampling period; This represents the standard velocity of sound corresponding to the matched fluid. This indicates the total number of sampling sub-time periods within the sampling period; This represents the actual speed of sound used to represent the propagation of the matched fluid within the pipe; This is the initial transmit power. To correct the transmission power, that is, the transmission power obtained after correcting the initial transmission power.

[0172] For impedance matching values, due to acoustic impedance ( For fluid density, When the sound speed approximation changes, the acoustic impedance of the flow also changes. In the embodiment, the equivalent acoustic impedance of the transducer is relatively stable in the case of fixed hardware. In order to maintain a good matching state between the transducer and the flow, the impedance matching value can be directly adjusted according to the change of the sound speed. The adaptive correction formula of the initial impedance matching value is as follows:

[0173] ;

[0174] wherein, is the corrected impedance matching value; is the initial impedance matching value; denotes the total number of sampling sub-periods in the sampling period; denotes the sound speed approximation corresponding to the i th sampling sub-period; denotes the i th sampling sub-period.

[0175] For the bandwidth, since the distribution range of the ultrasonic wave sound speed in different flows is different, the propagation and scattering of the ultrasonic wave signal will be affected. For example, for a mixed gas with large sound speed variation, a wider bandwidth is required to cover the sound speed variation range to accurately receive and process the signal. The transducer in the ultrasonic gas meter of the embodiment mainly uses a wide bandwidth covering the range of 50-200 kHz, so as to help the intelligent terminal to adjust the bandwidth by changing the frequency range of the excitation signal of the transducer or adjusting the filter parameters of the signal processing circuit. At the same time, the intelligent terminal can also use digital signal processing technology to adjust the cutoff frequency and passband width of the filter to optimize the bandwidth.

[0176] It should be particularly noted that, in the specific matching optimization process, since the driving circuit of the transducer includes a power adjustment module, the intelligent terminal can change the electric power applied to the transducer by adjusting the parameters of the power adjustment module, such as the amplification factor, the power voltage, etc., to adjust the transmission power. For the impedance matching value, the intelligent terminal can adjust the matching network pre-set in the transducer circuit, such as the matching circuit composed of transformer, inductor, capacitor, etc., and change the element parameters to adjust the impedance matching.

[0177] S700, generate a control instruction based on the recommended working parameter group, and send the control instruction to the transducer to replace the current working parameter group in the transducer with the recommended working parameter group;

[0178] ​​​The current working parameter group includes various current working parameters of the transducer in the sampling stage, and the current working parameters in the current working parameter group correspond one-to-one to the initial working parameters in the initial working parameter group; the recommended working parameter group includes a corrected transmission power and a corrected impedance matching value, which are used to ensure that the transducer can operate with optimal performance in a specific liquid environment, thereby ensuring that the ultrasonic gas meter achieves high-precision flow measurement; when generating the control instruction, the system first digitizes and encodes each parameter in the recommended working parameter group, i.e., the corrected transmission power, the corrected impedance matching value, and the corrected bandwidth of the transducer, according to a specific encoding rule. The encoding rule is adapted to the control interface protocol of the transducer to ensure that the transducer can accurately identify and respond to the instruction. For example, a binary encoding method is used to convert the numerical value of each parameter into a corresponding binary code sequence, and the code sequences of different parameters are arranged and combined in a predetermined order to form a complete control instruction data frame; after encoding is completed, the system sends the control instruction to the transducer using a special communication module. The communication module can be based on wired communication protocols such as RS-485, SPI, etc., or wireless communication technologies such as Bluetooth, Wi-Fi, etc., depending on the design of the transducer and the requirements of the application scenario. In the transmission process, in order to ensure the accuracy and reliability of the instruction transmission, the system will perform check processing on the control instruction, such as adding parity check bits, CRC (Cyclic Redundancy Check) codes, etc. The communication module sends the control instruction with the check information in the form of electrical signals or electromagnetic waves, and the signals are transmitted to the transducer through transmission lines or wireless channels.

[0179] After the transducer receives the control instruction, the internal control circuit of the transducer will perform decoding operation on the instruction. The control circuit restores the received binary code sequence to specific working parameter values according to the pre-set decoding rule; then, the control circuit adjusts the various functional modules inside the transducer according to these values, for example, by adjusting the gain of the power amplifier to change the transmission power, using a digital potentiometer or a programmable logic device to adjust the inductance and capacitance values in the impedance matching network to achieve the recommended impedance matching value, adjusting the bandwidth by changing the cutoff frequency of the filter or using a digital signal processing algorithm; through a series of operations, the current working parameter group in the transducer is successfully replaced by the recommended working parameter group, so that the transducer can operate in an optimized working state, providing solid hardware support for accurate flow measurement of the ultrasonic gas meter. This is the prior art, which will not be described here.

[0180] Based on the same inventive concept, the embodiment of the present application further discloses a kind of intelligent terminal, the intelligent terminal includes processor and memory, at least one instruction, at least one program, code set or instruction set are stored in memory, at least one instruction, at least one program, code set or instruction set can be loaded and executed by processor to realize the NB remote ultrasonic gas meter transducer matching optimization program algorithm provided in the method embodiment.

[0181] Based on the same inventive concept, the embodiment of the present application further discloses a kind of computer readable storage medium, the storage medium has at least one instruction, at least one program, code set or instruction set, at least one instruction, at least one program, code set or instruction set can be loaded and executed by processor to realize the NB remote ultrasonic gas meter transducer matching optimization program algorithm provided in the method embodiment.

[0182] It should be understood that "multiple" referred to herein means two or more. "And / or", which describes the association relationship of associated objects, means that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0183] Those skilled in the art can understand that all or part of the steps of the above-mentioned embodiments can be completed by hardware, or by program to instruct related hardware to complete, and the program can be stored in a computer readable storage medium, such as U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, and various storage medium that can store program code.

[0184] The above is only optional embodiment of the present application, and does not limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A transducer matching optimization method for NB remote ultrasonic gas meters, characterized in that, include: After the target fluid flows in the target pipeline for a period of time, the measurement data in the gas meter is continuously sampled within a preset sampling period to obtain a sampling dataset. The sampling period includes several sampling sub-periods, and the sampling dataset includes the downstream propagation time and the upstream propagation time of the ultrasonic wave in the target fluid. Based on the downstream propagation time and the upstream propagation time corresponding to each of the sampling sub-periods, a first sound velocity estimate of the ultrasonic wave in the target fluid is obtained, and the first sound velocity estimate corresponds one-to-one with the sampling sub-period; Based on all the first sound velocity estimates, a preliminary screening is performed in a preset fluid acoustic parameter database to obtain a preliminary screening database; Based on the first sound velocity estimate, a matching fluid corresponding to the target fluid is determined in the primary screening database; The initial set of operating parameters in the transducer is determined in the fluid acoustic parameter database based on the matched fluid. The initial operating parameter set is adaptively corrected based on all the first sound velocity estimates to obtain a recommended operating parameter set; a control command is generated based on the recommended operating parameter set and sent to the transducer to replace the current operating parameter set in the transducer with the recommended operating parameter set.

2. The transducer matching optimization method for NB remote ultrasonic gas meters according to claim 1, characterized in that, The fluid acoustic parameter database includes a set of acoustic parameters corresponding one-to-one with each known type of fluid. Each set of acoustic parameters includes the standard sound velocity of ultrasound in the corresponding fluid under a preset standard working environment and the comparative sound velocity of ultrasound in the corresponding fluid under several preset specific environments, where each specific environment corresponds one-to-one with the comparative sound velocity. The preliminary screening based on all the first sound velocity estimates within the preset fluid acoustic parameter database to obtain the initial screening database includes: Based on all the first sound velocity estimates, an approximate sound velocity value corresponding to the sampling period is obtained, and the approximate sound velocity value is used to reflect the actual sound velocity of the ultrasonic wave in the target fluid. The approximate sound speed value is input into a preset reference range calculation formula to obtain a reference sound speed interval corresponding to the target fluid; each standard sound speed is compared with the reference sound speed interval to determine whether the standard sound speed is within the reference sound speed interval. When the standard sound velocity is within the reference sound velocity range, the fluid corresponding to the standard sound velocity is used as the candidate fluid, and all the candidate fluids are used as the initial screening database.

3. The transducer matching optimization method for NB remote ultrasonic gas meters according to claim 2, characterized in that, The specific formula for calculating the reference range is as follows: in, This represents the approximate sound velocity of the ultrasonic signal in the target fluid during the sampling period; [c] min ,c max ] represents the reference sound speed range, c min c represents the minimum sound speed value within the reference sound speed range. max The maximum sound speed value in the reference sound speed range is represented by T0; the standard temperature corresponding to the preset standard environment is represented by p0; the standard pressure corresponding to the standard environment is represented by T; the actual temperature of the target pipeline is represented by T; the actual pressure of the target pipeline is represented by p; q is a correction coefficient and q∈(0,1); a1, a2, b1 and b2 are formula fitting coefficients and are constant terms.

4. The transducer matching optimization method for NB remote ultrasonic gas meters according to claim 3, characterized in that, The method of obtaining the approximate sound velocity value corresponding to the sampling time period based on all the first sound velocity estimates includes: The second sound speed estimate is calculated based on the downstream propagation time and the upstream propagation time. The formula for calculating the second sound speed estimate is as follows: Among them, c n，估计 ′ represents the second velocity of sound estimate corresponding to the nth sampling sub-time period; l 换能器 Indicates the propagation path of the ultrasonic signal; t n,顺流 t represents the downstream propagation time corresponding to the nth sampling sub-period; n，逆流 This represents the backflow propagation time corresponding to the nth sampling sub-period; The first sound speed estimate is verified based on the second sound speed estimate to obtain a verification result. The verification result includes the first sound speed estimate having a small error and the first sound speed estimate having a large error. When the verification result shows that the error of the first sound velocity estimate is small, the average value of all the first sound velocity estimates is directly used as the sound velocity approximation. When the verification result indicates that the first sound velocity estimate has a large error, an approximate sound velocity value is obtained based on the first sound velocity estimate and the second sound velocity estimate.

5. The transducer matching optimization method for NB remote ultrasonic gas meters according to claim 4, characterized in that, The step of determining the matching fluid corresponding to the target fluid based on the first sound velocity estimate in the primary screening database includes: The actual temperature and pressure inside the target pipe are obtained, and a target specific environment is matched according to the actual temperature and the actual pressure. The temperature corresponding to the target specific environment is used as the standard temperature, and the pressure corresponding to the target specific environment is used as the standard pressure. The target specific environment is a specific environment in the fluid acoustic parameter database. A comprehensive difference index is obtained based on the actual temperature, the actual pressure, the standard temperature, and the standard pressure; the degree of matching with each type of fluid is obtained based on the comprehensive difference index, the comparative sound velocity, and the approximate sound velocity value. The matching fluid is determined based on the degree of matching.

6. The transducer matching optimization method for NB remote ultrasonic gas meters according to claim 5, characterized in that, The comprehensive difference index is calculated as follows: D i =w T ·ΔT i +w P ·Δp i ; ΔT i =|T t -T0|; Δp i =|p t -p0|; Among them, D i For comprehensive difference indicators; w T w P These are pre-set temperature and pressure weighting coefficients; T t p represents the actual temperature inside the target pipe. t T0 represents the actual pressure inside the target pipeline; T0 represents the standard temperature corresponding to the specific environment of the target; p0 represents the standard pressure corresponding to the specific environment of the target. The formula for calculating the matching degree is as follows: ΔC i =|C t -C0|; M=1-(D i +C); Among them, C t C0 represents the relative speed of sound to the target's specific environment; C0 represents the approximate current speed of sound; c maxdiff C represents the maximum possible difference in sound velocity; M represents the quantized value of the sound velocity difference; and M represents the degree of matching.

7. The transducer matching optimization method for NB remote ultrasonic gas meters according to claim 6, characterized in that, The initial operating parameter set includes the initial transmit power and initial impedance matching value of the transducer. The fluid acoustic parameter database also includes several initial operating parameters corresponding to each type of fluid. The initial operating parameter set is adaptively corrected based on all the first sound velocity estimates to obtain the following calculation formula in the recommended operating parameter set: Among them, c i This represents the approximate sound velocity corresponding to the i-th sampling sub-time period; c represents the average value of the approximate sound velocity over the entire sampling period; c0 represents the standard sound velocity corresponding to the matching fluid; k represents the total number of sampling sub-periods within the sampling period; c′ is the actual sound velocity value used to represent the propagation of the matching fluid within the pipe; P0 is the initial transmission power, P′ is the corrected transmission power, i.e., the transmission power obtained after correcting the initial transmission power; Z′ is the corrected impedance matching value; Z0 is the initial impedance matching value; j represents the j-th sampling sub-period; p represents the fluid density corresponding to the matching fluid.

8. A smart terminal, characterized in that, It includes a memory and a processor, wherein the memory stores an instruction set, which is loaded and executed by the processor to implement the transducer matching optimization method for NB remote ultrasonic gas meters as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The readable storage medium stores an instruction set, which is loaded and executed by a processor to implement the transducer matching optimization method for NB remote ultrasonic gas meters as described in any one of claims 1 to 7.

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