A method and system for measuring and processing jet fuel water separation index based on ultraviolet spectrum

Abstract

The present invention discloses a method and system for measuring the water separation index of jet fuel based on ultraviolet spectrum, and belongs to the technical field of jet fuel detection. The present invention determines the wavelength of the ultraviolet spectrum band of the jet fuel to be measured, pre-processes the jet fuel to be measured, obtains a stable amplified output voltage signal after processing by an optical subsystem and a signal processing subsystem, and calculates the water separation index of the jet fuel to be measured by using a fitted water separation index model. When the present invention is used to measure jet fuel, it has the advantages of stable reading, high measurement accuracy, easy carrying, stable performance, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of jet fuel detection, and in particular relates to a jet fuel water separation index measurement and processing method and system based on ultraviolet spectrum. Background Art

[0002] Jet fuel is a light petroleum product and is the propulsion fuel for modern large civil aviation and air force aircraft engines. The quality of jet fuel is crucial to flight safety and directly affects the performance of the aircraft. The main jet fuel quality control test items include: composition, cleanliness, distillation range, flammability, fluidity and other index parameters. The most important evaluation index of cleanliness is the water separation index, which measures the ability of jet fuel to separate water when passing through a glass fiber filter medium. The index ranges from 50 to 100. The higher the value, the cleaner and more transparent the fuel.

[0003] Excessive surfactants in jet fuel, such as sulfonates and cyclopentaneates, can easily lead to problems such as oil-water separation and water not being easy to settle, thereby reducing the water separation index of the fuel. When the water separation index of jet fuel is too low, it will affect the dehydration effect of the aircraft's fuel system, and it is very easy to cause fuel freezing in a high-altitude and low-temperature environment. In severe cases, it can cause engine failure and cause flight accidents. Therefore, how to efficiently and accurately measure the water separation index of jet fuel is particularly important in the aerospace field.

[0004] At present, the determination of jet fuel water separation index is mainly based on the national standard GB 11129-89 "Jet fuel water separation index determination method (portable separation instrument method)" and the petrochemical standard SH / T 0616-95 "Jet fuel water separation index determination method". However, the instruments made according to the above two standards have unstable readings and low measurement accuracy, which cannot meet the stable real-time measurement needs. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for measuring the water separation index of jet fuel based on ultraviolet spectrum.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: using a dedicated system for measuring the water separation index of jet fuel, ultraviolet light of a specific band is optically collimated to irradiate the jet fuel sample to be measured, and the generated transmitted light is focused on a photodetector; the photocurrent generated by the photodetector is processed by a signal processing circuit to obtain a measured voltage value, which is sent to a water separation index calculation model to obtain the water separation index of the jet fuel.

[0007] A method for measuring the water separation index of jet fuel based on ultraviolet spectroscopy, characterized in that the measuring steps are as follows:

[0008] 1) Assembling an optical subsystem and a signal processing subsystem; the optical subsystem is used to irradiate the jet fuel to be tested with ultraviolet light to obtain a spectrum, which is emitted as a current signal; the signal processing subsystem is used to receive the current signal emitted by the optical subsystem, convert it into a voltage signal, and then emit it as a voltage signal after amplification, stability enhancement, and low-frequency noise removal operations;

[0009] 2) Determine the wavelength of the ultraviolet spectrum band of the jet fuel to be tested by using a spectrometer measurement and analysis method;

[0010] 3) Pre-treating the jet fuel to be tested, mixing it with trace water for emulsification, and then separating the trace water;

[0011] 4) The pre-processed jet fuel to be tested is processed by the optical subsystem and the signal processing subsystem to obtain an output voltage signal;

[0012] 5) Fitting the water separation index model;

[0013] 6) Calculate the water separation index of the jet fuel to be tested using the fitted water separation index model.

[0014] Preferably, the water separation index model includes a linear water separation index model and a nonlinear water separation index model.

[0015] Further preferably, the linear water separation index model fitting steps are as follows:

[0016] a. Obtaining the control voltage signal: When no jet fuel is placed, the ultraviolet light source obtains the control voltage signal through the optical subsystem and the signal processing subsystem;

[0017] b. Acquisition of absorption spectrum voltage signal of jet fuel with known water separation index: When jet fuel with known water separation index is placed, the ultraviolet light source obtains absorption spectrum voltage signal of jet fuel with known water separation index through the optical subsystem and the signal processing subsystem;

[0018] c. Calculate the voltage difference ratio: subtract the voltages obtained in step a from the voltages obtained in step b, take the absolute value of the difference, and divide it by the reference voltage to obtain the voltage difference ratio;

[0019] d. All the voltage difference ratios obtained were used as independent variables and all the water separation indices were used as dependent variables. Linear function fitting was performed to obtain the linear water separation index model.

[0020] Further preferably, the nonlinear water separation index model fitting steps are as follows:

[0021] a. Data collection of light source spectrum of training samples: Select standard jet fuel with known water separation index and collect its light source spectrum data through spectrometer;

[0022] b. Preprocessing of light source spectrum data: When the wavelength of the ultraviolet spectrum band of the jet fuel to be tested is determined by the spectrometer measurement and analysis method, the light source spectrum data is collected and processed to reduce background noise;

[0023] c Feature band selection: select the band with obvious and easy-to-distinguish features in the preprocessed light source spectrum data as the feature band;

[0024] d. Construction of RBM model and extraction of identification features: constructing an RBM model, using the model to remove redundant information of preprocessed light source spectrum data, and extracting identification features that characterize the water separation index;

[0025] e Extreme learning machine training: The obtained identification features are divided into a training set and a test set in proportion, and the training set is used to obtain a trained extreme learning machine model, which is a nonlinear water separation index model.

[0026] Preferably, when the wavelength of the ultraviolet spectrum band of the jet fuel to be tested is determined by using a spectrometer measurement and analysis method, the steps are as follows:

[0027] a. Turn on the spectrometer and preheat it. Take an appropriate amount of jet fuel reference liquid, perform external emulsification and water separation operations, and then take an appropriate amount as the jet fuel to be tested;

[0028] b. The ultraviolet light source of the spectrometer irradiates the jet fuel to be tested after passing through the collimation system. The attenuated light is coupled through the optical fiber and then transmitted back to the spectrometer for measurement to obtain the spectral data.

[0029] c Select a standard jet fuel with a known water separation index, use the ultraviolet absorption spectrum of its water separation index as the ordinate, and use the obtained spectral data as the abscissa to obtain a spectrum graph; in the spectrum graph, select a range where there is an obvious characteristic absorption peak and the spectral intensity is close to a linear range with the water separation index, which is the wavelength of the ultraviolet spectrum band of the jet fuel to be tested.

[0030] The present invention relates to a system for measuring a jet fuel water separation index based on ultraviolet spectrum, which is characterized by comprising an optical subsystem and a signal processing subsystem; the optical subsystem is used to convert a spectrum obtained by irradiating the jet fuel to be measured with ultraviolet light into a current signal; the signal processing subsystem is used to receive the current signal emitted by the optical subsystem and convert it into a temperature voltage signal that is amplified and has low-frequency noise removed.

[0031] Preferably, the optical subsystem includes an optical path structure, a light source emitting device, a collimating lens, a measuring cell, a focusing lens and a photoelectric receiver; the optical path structure includes a light source mounting cavity, a front lens mounting cavity, a measuring cavity, a rear lens mounting cavity and a receiver mounting cavity; the measuring cavity is a groove, and through holes are arranged in front and behind it; the light source emitting device, the collimating lens, the measuring cell, the focusing lens and the photoelectric receiver are fixed in the light source mounting cavity, the front lens mounting cavity, the measuring cavity, the rear lens mounting cavity and the receiver mounting cavity of the optical path structure in sequence.

[0032] Further preferably, holes are opened on both side walls of the measuring cavity for heat dissipation.

[0033] Preferably, the signal processing subsystem includes, from front to back, a current / voltage conversion module, a voltage amplification module, a voltage bias module and a signal filtering module; the current / voltage conversion module is used to receive a current signal and convert it into a voltage signal; the voltage amplification module is used to amplify the voltage signal; the voltage bias module is used to increase the stability of the amplified voltage signal; and the signal filtering module is used to remove low-frequency noise of the amplified voltage signal.

[0034] The present invention relates to a method and system for measuring the water separation index of jet fuel based on ultraviolet spectrum. After the wavelength of the ultraviolet spectrum band of the jet fuel to be measured is determined and the jet fuel to be measured is pre-processed, a stable amplified output voltage signal is obtained after processing by an optical subsystem and a signal processing subsystem, and the water separation index of the jet fuel to be measured is calculated using a fitted water separation index model. When the present invention is used to measure jet fuel, it has the advantages of stable reading, high measurement accuracy, easy carrying, stable performance, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It shows the UV absorption spectrum of standard jet fuel;

[0036] Figure 2 It shows the schematic diagram of the optical subsystem;

[0037] Figure 3 It shows the structural diagram of the current / voltage signal conversion amplification and conditioning circuit;

[0038] Figure 4 Shown is a flow chart of the water separation index nonlinear method.

[0039] Among them, 1-optical subsystem, 101-light source emitting device, 102-collimating lens, 103-measuring cell, 104-focusing lens, 105-photoelectric receiver, 2-signal processing subsystem, 201-current / voltage conversion module, 202-voltage amplification module, 203-voltage bias module, 204-signal filtering module. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the embodiments and drawings, but is not intended to limit the technical solution of the present invention.

[0041] Example 1

[0042] The system for measuring and processing the jet fuel water separation index based on ultraviolet spectrum in this embodiment includes an optical subsystem 1 and a signal processing subsystem 2.

[0043] The optical subsystem 1 includes an optical path structure, a light source emitting device 101, a collimating lens 102, a measuring cell 103, a focusing lens 104 and a photoelectric receiver 105. Figure 3 As shown. Among them:

[0044] The optical path structure is 50mm in total length and 50mm in height. It is made of aluminum alloy. Its inner cavity includes the light source installation cavity, the front lens installation cavity, the measurement cavity, the rear lens installation cavity and the receiver installation cavity from front to back. The measurement cavity is a groove with a length of 13mm, a width of 13mm and a depth of 50mm. A through hole with a diameter of 5mm is opened along the front and rear wall panels. The center of the circle is located 30mm above the bottom of the groove body. A 35mm×8mm rectangular hole is opened on the two side wall panels for heat dissipation.

[0045] The light source emitting device 101 has an outer diameter of 4.7 mm, a field of view of ±8°, and an applied forward voltage of 3.5 V; the wavelength of the emitted light is typically 350 nm, and the wavelength range is 345 to 355 nm.

[0046] The collimating lens 102 is made of K9, has a diameter of 5 mm, a focal length of 5 mm, and a 355 nm anti-reflection film HT>99.5%.

[0047] The measuring cell 103 is a quartz cuvette cell with a width of 1 cm.

[0048] The outer diameter of the photoelectric receiver 105 is 4.7 mm, the spectral response range is 230-395 nm, and the photocurrent is 163 nA.

[0049] The light source emitting device 101, the collimating lens 102, the measuring cell 103, the focusing lens 104 and the photoelectric receiver 105 are fixed in sequence in the light source mounting cavity, the front lens mounting cavity, the measuring cavity, the rear lens mounting cavity and the receiver mounting cavity of the optical path structure 1; the jet fuel to be tested is contained in the measuring cell 103. After installation, the collimating lens 102 is 10 mm away from the light source.

[0050] The signal processing subsystem 2 is a current / voltage signal conversion, amplification and conditioning circuit, the input of which is the current signal of the photoelectric receiver 105, and the output is a voltage signal provided to the processing system, including: a current / voltage conversion module 201, a voltage amplification module 202, a voltage bias module 203 and a signal filtering module 204; wherein:

[0051] The current / voltage conversion module 201 is used to receive the current signal output by the optical subsystem 1 and convert the received current signal into a voltage signal, with a typical voltage value of 20 mV.

[0052] The voltage amplification module 202 is used to amplify the voltage signal according to formula (1) to obtain an amplified voltage signal:

[0053] β=-(R4+R5)÷R7(1)

[0054] Among them, β is the reverse gain, R4 and R5 are feedback resistors, R7 is the input resistor, and the reverse gain is typically set to 120 times.

[0055] The voltage bias module 203 is used to use a subtractor to add a DC offset to the amplified voltage signal to increase the stability of the amplified voltage signal.

[0056] The signal filtering module 204 is used to remove low-frequency noise from the amplified voltage signal to obtain an output voltage signal.

[0057] When the jet fuel water separation index measurement and processing method based on ultraviolet spectrum of this embodiment is used to measure the water separation index of a jet fuel sample using a system, the steps are as follows:

[0058] First, the wavelength of the ultraviolet spectrum band is determined by spectrometer measurement and analysis. Data is collected using a spectrometer that uses a deep ultraviolet deuterium lamp as a light source, with a sampling interval of 0.23nm and a detection range of 189.96 to 644nm. The specific collection process is as follows:

[0059] 1) Turn on the UV deuterium lamp light source of the spectrometer and preheat for 15 minutes. Take 50 mL of jet fuel reference solution and perform external emulsification and separation operations to separate the water. Then take 15 mL as the jet fuel to be tested, add it to a quartz cuvette cell with a width of 1 cm and let it stand for 1 minute.

[0060] 2) The incident light of the spectrometer is transmitted to the collimation system through the optical fiber and then enters the quartz cuvette cell. After being absorbed and attenuated by the jet fuel to be measured in the quartz cuvette cell, the attenuated light is transmitted to the spectrometer for measurement through optical fiber coupling, and spectral data of 2068 wavelength points are obtained in total.

[0061] 3) Using the ultraviolet absorption spectra of seven standard jet fuel water separation indices of 65, 70, 72, 80, 88, 89, and 99 as the ordinate and the spectrum data obtained in step 2 as the abscissa, the obtained spectrum is as follows: Figure 1As shown, by enlarging the local spectrum, the absorption spectrum data of jet fuel in the 340-360nm band can be obtained, which is more distinguishable and has obvious characteristic absorption peaks. Therefore, in order to more accurately analyze the ultraviolet absorption spectrum of jet fuels with different water separation indexes, the wavelength of the luminous band should be selected within the range where the spectral intensity is close to linear with the water separation index. Combined with the actual light source wavelength, this embodiment finally selects an LED light source with a luminous band wavelength range of 345-355nm.

[0062] Secondly, in order to measure the jet fuel absorption spectrum, the jet fuel needs to be pre-processed. The specific steps are as follows:

[0063] 1) Rinse the prepared syringe twice with the jet fuel to be tested.

[0064] 2) Add the jet fuel to be tested and a trace amount of water in a syringe at a volume ratio of 1000:1, and emulsify using an emulsifying device to obtain an emulsion.

[0065] 3) Remove the air bubbles in the syringe and place the syringe into the water separation and pushing structure. Under the control of the controller, push the emulsion from the syringe to the coalescer at a speed of 1 mm / s. The coalescer separates the jet fuel to be tested and trace water in the emulsion, obtains the separated jet fuel to be tested and places it in the pre-prepared measuring cell 103.

[0066] The third step is to use the optical subsystem 1 and the signal processing subsystem 2 to measure the jet fuel absorption spectrum. The specific steps are as follows:

[0067] 1) According to the ultraviolet spectrum light source test conditions, the responsivity of the photoelectric receiver 105 is set to 0.12A / W.

[0068] The voltage value of the current / voltage conversion module 201 is set to 20 mV.

[0069] 2) Start the optical subsystem 1 and the signal processing subsystem 2.

[0070] 3) The ultraviolet light emitted by the light source emitting device 101 of the optical subsystem 1 passes through the collimating lens 102 and is vertically incident on the jet fuel to be tested in the measuring cell 103. The incident light is transmitted through the jet fuel to be tested and then passes through the focusing lens 104. Finally, it is received by the photoelectric receiver 105 and emitted in the form of a current signal.

[0071] 4) After receiving the current signal from the photoelectric receiver 105, the current / voltage conversion module 201 of the signal processing subsystem 2 converts it into a voltage signal; the voltage signal is amplified by the voltage amplification module 202 to obtain an amplified voltage signal; and then the voltage bias module 203 superimposes the DC offset and the signal filtering module 204 removes the low-frequency noise to obtain an output voltage signal.

[0072] Finally, the linear water separation index model is used to calculate the water separation index of the jet fuel to be tested. The specific steps are as follows:

[0073] 1) Acquisition of reference voltage signal: When no jet fuel is placed in the measuring cell 103 of the optical subsystem 1 , the absorption spectrum obtained by the ultraviolet LED light source is passed through the signal processing subsystem 2 to obtain a reference voltage signal.

[0074] 2) Acquisition of absorption spectrum voltage signal of jet fuel with known water separation index: When jet fuel with a water separation index of 65 is placed in the measuring cell 103 of the optical subsystem 1, the absorption spectrum obtained by the ultraviolet LED light source is passed through the signal processing subsystem 2 to obtain the absorption spectrum voltage signal of the jet fuel with known water separation index.

[0075] 3) Calculate the voltage difference ratio: subtract the voltages obtained in step 1) from the voltages obtained in step 2), take the absolute value of the difference, and divide it by the reference voltage to obtain the voltage difference ratio.

[0076] 4) Obtaining a linear model: Repeat steps 1) to 3) to obtain the voltage difference ratios of jet fuels with water separation indexes of 70, 72, 80, 88, 89, and 99. Linear function fitting is performed using all the obtained voltage difference ratios as independent variables and all the water separation indices as dependent variables.

[0077] 5) Water separation index test: The control voltage and the voltage of the jet fuel to be tested are obtained through the signal processing subsystem 2, and then the difference ratio is calculated and substituted into the linear model of step 4) to obtain the water separation index of the jet fuel to be tested.

[0078] Example 2

[0079] When measuring the water separation index of a jet fuel sample in this embodiment, the steps are as follows:

[0080] First, the wavelength of the ultraviolet spectrum band is determined by spectrometer measurement and analysis. Data is collected using a spectrometer that uses a deep ultraviolet deuterium lamp as a light source, with a sampling interval of 0.23nm and a detection range of 189.96 to 644nm. The specific collection process is as follows:

[0081] 1) Turn on the UV deuterium lamp light source of the spectrometer and preheat it for 15 minutes. After preheating, record the light source spectrum data.

[0082] Take 50 mL of jet fuel reference solution and perform external emulsification and separation operations to separate the water. Then take 15 mL as the jet fuel to be tested, add it to a quartz cuvette with a width of 1 cm and let it stand for 1 minute.

[0083] 2) The incident light of the spectrometer is transmitted to the collimation system through the optical fiber and then enters the quartz cuvette cell. After being absorbed and attenuated by the jet fuel to be measured in the quartz cuvette cell, the attenuated light is transmitted to the spectrometer for measurement through optical fiber coupling, and spectral data of 2068 wavelength points are obtained in total.

[0084] 3) Select the ultraviolet absorption spectra of seven standard jet fuel water separation indices of 65, 70, 72, 80, 88, 89, and 99 as the ordinate, and the spectrum data obtained in step 2 as the abscissa. The obtained spectrum is as follows: Figure 1 As shown, by enlarging the local spectrum, the absorption spectrum data of jet fuel in the 340-360nm band can be obtained, which is more distinguishable and has obvious characteristic absorption peaks. Therefore, in order to more accurately analyze the ultraviolet absorption spectrum of jet fuels with different water separation indexes, the wavelength of the luminous band should be selected within the range where the spectral intensity is close to linear with the water separation index. Combined with the actual light source wavelength, this embodiment finally selects an LED light source with a luminous band wavelength range of 345-355nm.

[0085] Secondly, in order to measure the jet fuel absorption spectrum, the jet fuel needs to be pre-processed. The specific steps are as follows:

[0086] 1) Rinse the prepared syringe twice with the jet fuel to be tested.

[0087] 2) Add the jet fuel to be tested and a trace amount of water in a syringe at a volume ratio of 1000:1 and emulsify using an emulsifying device to obtain an emulsion.

[0088] 3) Remove the air bubbles in the syringe and place the syringe into the water separation push structure. Under the control of the controller, push the emulsion from the syringe to the coalescer at a speed of 1 mm / s. The coalescer separates the jet fuel to be tested and trace water in the emulsion, obtains the separated jet fuel to be tested and places it in the pre-prepared measurement pool 103.

[0089] The third step is to use the optical subsystem 1 and the signal processing subsystem 2 to measure the jet fuel absorption spectrum. The specific steps are as follows:

[0090] 1) According to the ultraviolet spectrum light source test conditions, the responsivity of the photoelectric receiver 105 is set to 0.12A / W.

[0091] The voltage value of the current / voltage conversion module 201 is set to 40 mV.

[0092] 2) Start the optical subsystem 1 and the signal processing subsystem 2.

[0093] 3) The ultraviolet light emitted by the light source emitting device 101 of the optical subsystem 1 passes through the collimating lens 102 and is vertically incident on the jet fuel to be tested in the measuring cell 103. The incident light is transmitted through the jet fuel to be tested and then passes through the focusing lens 104. Finally, it is received by the photoelectric receiver 105 and emitted in the form of a current signal.

[0094] 4) After receiving the current signal from the photoelectric receiver 105, the current / voltage conversion module 201 of the signal processing subsystem 2 converts it into a voltage signal; the voltage signal is amplified by the voltage amplification module 202 to obtain an amplified voltage signal; and then the voltage bias module 203 superimposes the DC offset and the signal filtering module 204 removes the low-frequency noise to obtain an output voltage signal.

[0095] Finally, the nonlinear water separation index model is used to calculate the water separation index of the jet fuel to be tested. The processing method is as follows: Figure 4 As shown, the specific steps are as follows:

[0096] 1) Training sample light source spectral data collection: The ultraviolet light source is passed through 7 jet fuels with known water separation indexes of 65, 70, 72, 80, 88, 89, and 99, and the spectral data are collected by a spectrometer to obtain the light source spectral data corresponding to each jet fuel with a water separation index.

[0097] 2) Light source spectrum data preprocessing: The collected light source spectrum data is preprocessed. In the process of data preprocessing, in order to reduce the interference of background noise, the light source spectrum S0 and dark spectrum S dark In the process of data preprocessing, the dark spectrum is regarded as noise, and the light source spectrum and the absorption spectrum are subtracted from the dark spectrum respectively. The preprocessed light source spectrum data D(λ) is calculated by formula (2).

[0098]

[0099] 3) Feature band selection: sort out the light source spectrum data after preprocessing in step 2) and select bands with obvious characteristics and easy to distinguish to obtain feature bands.

[0100] 4) Restricted Boltzmann Machine (RBM) Model Construction and Identification Feature Extraction: The preprocessed light source spectrum data has a lot of redundant information, so the preprocessed spectrum data is subjected to feature extraction through a deep belief network to obtain identification features that characterize the water separation index. The deep belief network for feature extraction consists of 10 layers of restricted Boltzmann machines. First, the relevant parameters of the RBM are initialized to obtain the initial RBM network model; the preprocessed light source spectrum data is input into the input layer of the restricted Boltzmann machine for training, and an output layer containing a certain level of feature information can be obtained. The output layer of the first layer of restricted Boltzmann machine is connected to the input layer of the second layer of restricted Boltzmann machine, and the second layer of restricted Boltzmann machine extracts the feature information for a second time. By analogy, a total of ten extractions of feature information are performed to complete one iteration. After the first iteration is completed, the RBM parameters are adjusted by calculating the loss value of the output layer and the label data, and the original data is re-input into the network to extract ten layers of feature information to complete the second iteration. This embodiment undergoes a total of 1000 iterations to obtain identification features that characterize the water separation index, which are used as input data for subsequent water separation index analysis.

[0101] 5) Extreme learning machine training: The identification features obtained in step 4) are divided into a training set and a test set in a ratio of 5:3, and the training set is input into the initialized extreme learning machine model for training, and finally a trained extreme learning machine model is obtained.

[0102] 6) Water separation index test: The spectrometer collects the spectrum data of the jet fuel to be tested by the light source for multiple times to obtain the test data. The test data is input into the trained extreme learning machine for testing to obtain the water separation index of the jet fuel to be tested.

[0103] The nonlinear water separation index model of this embodiment is used to calculate and process three jet fuels with known water separation indexes of 65, 70, and 89, and the test results can be seen in Table 1. The test results show that the nonlinear water separation index model calculation and processing method of this embodiment is closer to the true value, and the measurement results are stable, and the maximum relative error can be controlled within 2%, which is better than the measurement accuracy of other traditional algorithms and can better meet the actual measurement needs.

[0104] Table 1 Prediction mean and standard deviation of various methods in the 330-370 nm band

[0105]

Claims

1. A method for measuring the water separation index of jet fuel based on ultraviolet spectroscopy, characterized in that: The measurement steps are as follows: 1) Assembling an optical subsystem (1) and a signal processing subsystem (2); the optical subsystem (1) is used to irradiate the jet fuel to be tested with ultraviolet light to obtain a spectrum, and emit it as a current signal; the signal processing subsystem (2) is used to receive the current signal emitted by the optical subsystem (1), convert it into a voltage signal, and then emit it as a voltage signal after amplification, stability enhancement and low-frequency noise removal operations; 2) Determine the wavelength of the ultraviolet spectrum band of the jet fuel to be tested by using a spectrometer measurement and analysis method; 3) Pre-treat the jet fuel to be tested, mix it with trace water at a volume ratio of 1000:1 for emulsification, and then separate the trace water; 4) The pre-processed jet fuel to be tested is processed by the optical subsystem (1) and the signal processing subsystem (2) to obtain an output voltage signal; 5) Fitting the nonlinear water separation index model, the steps are as follows: a. Data collection of light source spectrum of training samples: Select standard jet fuel with known water separation index and collect its light source spectrum data through spectrometer; b. Preprocessing of light source spectrum data: When the wavelength of the ultraviolet spectrum band of the jet fuel to be tested is determined by the spectrometer measurement and analysis method, the light source spectrum data is collected and processed to reduce background noise; c. Feature band selection: select the band with obvious and easily distinguishable features in the pre-processed spectrum data of the jet fuel light source to be tested as the feature band; d. Construction of RBM model and extraction of identification features: constructing an RBM model, using the model to remove redundant information of preprocessed light source spectrum data, and extracting identification features that characterize the water separation index; e) Extreme learning machine training: the obtained identification features are divided into a training set and a test set in proportion, and the trained extreme learning machine model is obtained using the training set, which is the nonlinear water separation index model; 6) the water separation index of the jet fuel to be tested is calculated using the fitted nonlinear water separation index model.

2. The method for measuring the jet fuel water separation index based on ultraviolet spectroscopy according to claim 1, characterized in that: When the wavelength of the ultraviolet spectrum band of the jet fuel to be tested is determined by the spectrometer measurement and analysis method, the steps are as follows: a. Turn on the spectrometer and preheat it. Take an appropriate amount of jet fuel reference liquid, perform external emulsification and water separation operations, and then take an appropriate amount as the jet fuel to be tested; b. The ultraviolet light source of the spectrometer irradiates the jet fuel to be tested after passing through the collimation system. The attenuated light is coupled through the optical fiber and then transmitted back to the spectrometer for measurement to obtain the spectral data. c Select a standard jet fuel with a known water separation index, use the ultraviolet absorption spectrum of its water separation index as the ordinate, and use the obtained spectral data as the abscissa to obtain a spectrum graph; in the spectrum graph, select a range where there is an obvious characteristic absorption peak and the spectral intensity is close to a linear range with the water separation index, which is the wavelength of the ultraviolet spectrum band of the jet fuel to be tested.

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