Method for accurately measuring dielectric constant of nonlinear insulating medium

Abstract

The invention discloses a method for accurately measuring the dielectric constant of a nonlinear insulating medium, and relates to the technical field of electrical insulation testing. In order to solve the technical defect that in the prior art, a measuring method capable of effectively eliminating the thickness influence and accurately obtaining the real dielectric constant of the nonlinear insulating medium does not exist, the technical scheme provided by the invention comprises the following steps: constructing an equivalent circuit model; collecting dielectric constant measurement values of the samples with different thicknesses, and performing relative dielectric constant testing on the samples with different thicknesses at a plurality of frequency points by using a broadband dielectric spectrometer to obtain data of dielectric constants changing along with the thicknesses; judging whether the dielectric constant has thickness dependence or not; if the thickness dependence exists, the dielectric constant measurement value is substituted into the equivalent circuit model for nonlinear fitting, and the real dielectric constant value of the material is extracted; and outputting a real dielectric constant. The method can be applied to dielectric property accurate measurement and insulation structure design analysis work of nonlinear insulation materials.

Description

Technical Field

[0001] It relates to the technical field of electrical insulation testing, specifically to measuring the dielectric constant of non-linear insulating media. Background Art

[0002] In an electrical insulation system, the dielectric constant of a material is a key parameter for evaluating its electrical performance and applicability. In recent years, with the development of high-voltage power equipment, miniaturized power electronic systems, and advanced insulation structures, more and more research has focused on the application and performance testing of non-linear insulating media. Especially in complex electric field distributions or high-field-strength environments, non-linear dielectric materials with field-enhanced conductivity (i.e., their conductivity increases with the increase of the electric field) exhibit excellent electric field regulation capabilities, and thus are widely used in insulation structures such as cable terminals, motor bar ends, and high-voltage joints.

[0003] Such non-linear materials are usually achieved by doping micron or nano-scale semi-conductive inorganic fillers (such as SiC, ZnO, etc.) in an insulating matrix (such as epoxy resin, polyethylene, etc.). The prepared composite dielectric not only has excellent insulation performance, but also can effectively regulate the electric field distribution in the high-field region, slow down the electric field concentration, thereby prolonging the insulation life of the equipment and improving the reliability of the system. In recent years, many scholars have developed a variety of new non-linear insulating materials based on this technical route and characterized their performance through means such as dielectric spectrometers and conductivity tests. For example, SiC / EP composites have been widely studied and used in various high-voltage application scenarios due to their excellent thermal stability and non-linear conductance characteristics.

[0004] However, in the actual testing process, there are still many challenges in accurately obtaining the dielectric constant. Existing research has shown that the test results of the dielectric constant of non-linear composite materials often vary significantly under different sample thicknesses, and this phenomenon is particularly obvious in high-conductivity composite dielectrics. This is mainly attributed to the possible formation of an electric double layer structure at the contact interface between the electrode and the sample, especially in low-frequency dielectric spectroscopy tests. The formation of the electric double layer will introduce an additional equivalent capacitance, making the actual measurement results deviate from the true dielectric response of the material. Traditional measurement methods do not correct for the influence of the electric double layer, resulting in the measured dielectric constant varying with thickness and being difficult to reflect the intrinsic characteristics of the material.

[0005] Therefore, in the prior art, there is still a lack of a measurement method that can effectively eliminate the influence of thickness and accurately obtain the true dielectric constant of non-linear insulating media, and this problem restricts the in-depth research and engineering application of non-linear insulating materials. Summary of the Invention

[0006] To solve the technical defect in the prior art that there is still a lack of a measurement method that can effectively eliminate the influence of thickness and accurately obtain the true dielectric constant of non-linear insulating media, the technical solution provided by the present invention is as follows:

[0007] A method for accurately measuring the dielectric constant of a non-linear insulating medium, comprising:

[0008] Steps for constructing an equivalent circuit model;

[0009] Steps for collecting dielectric constant measurement values of specimens with different thicknesses, using a broadband dielectric spectrometer to test the relative dielectric constant of specimens with different thicknesses at multiple frequency points, and obtaining data on the variation of the dielectric constant with thickness;

[0010] Steps for judging whether the dielectric constant has thickness dependence based on the data of the variation of the dielectric constant with thickness;

[0011] If it has thickness dependence, substituting the dielectric constant measurement values into the equivalent circuit model for non-linear fitting to extract the true dielectric constant value of the material;

[0012] Steps for outputting the true dielectric constant.

[0013] Furthermore, a preferred embodiment is provided. In the equivalent circuit model, the measured capacitance of the non-linear insulating medium to be measured is represented by a circuit model composed of a Stern layer capacitance, a diffusion layer capacitance, and a specimen bulk capacitance connected in series.

[0014] Furthermore, a preferred embodiment is provided. The Spearman rank correlation coefficient is used to analyze the correlation between the relative dielectric constant and the specimen thickness to judge whether the dielectric constant has thickness dependence.

[0015] Furthermore, a preferred embodiment is provided. The measurement frequency range of the broadband dielectric spectrometer is 0.1 Hz to 1 MHz.

[0016] Furthermore, a preferred embodiment is provided. The non-linear fitting is performed using the non-linear least squares method for parameter fitting, and the fitting variables include two equivalent capacitance values in the electric double layer and the true dielectric constant of the material.

[0017] Furthermore, a preferred embodiment is provided. The multiple frequency points include representative frequencies in the low-frequency band, the middle-frequency band, and the high-frequency band.

[0018] Based on the same inventive concept, the present invention also provides a device for accurately measuring the dielectric constant of a non-linear insulating medium, comprising:

[0019] A module for constructing an equivalent circuit model;

[0020] A module for collecting dielectric constant measurement values of specimens with different thicknesses, using a broadband dielectric spectrometer to test the relative dielectric constant of specimens with different thicknesses at multiple frequency points, and obtaining data on the variation of the dielectric constant with thickness;

[0021] A module for determining whether the dielectric constant has thickness dependence based on data of the change of the dielectric constant with thickness;

[0022] If it has thickness dependence, a module for substituting the measured value of the dielectric constant into an equivalent circuit model for non-linear fitting and extracting the true dielectric constant value of the material;

[0023] A module for outputting the true dielectric constant.

[0024] Based on the same inventive concept, the present invention also provides a computer storage medium for storing a computer program, and when the computer program is read by a computer, the computer executes the method described above.

[0025] Based on the same inventive concept, the present invention also provides a computer, including a processor and a storage medium, and when the processor reads the computer program stored in the storage medium, the computer executes the method described above.

[0026] Based on the same inventive concept, the present invention also provides a computer program product, which, as a computer program, when executed, implements the method described above.

[0027] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0028] By constructing a non-linear composite dielectric equivalent circuit model considering the electric double layer effect, the present invention effectively explains the phenomenon that the measurement results are inconsistent due to the change of the sample thickness in the traditional dielectric constant test. Compared with the method in the prior art that simply adopts a single-layer capacitance model and ignores the influence of interfacial polarization, the present invention introduces two series capacitance elements of the Stern layer and the diffusion layer in the modeling stage, making the measurement system more in line with the actual physical structure, theoretically revealing the fundamental reason for the thickness dependence, and thus providing a scientific basis for subsequent elimination.

[0029] By using a broadband dielectric spectrometer to measure the dielectric constant of samples with different thicknesses and combining frequency segmentation (low frequency, medium frequency, high frequency) to extract the data of characteristic frequency points, the present invention can comprehensively capture the thickness dependence behavior under different frequency responses. Compared with the method in the existing research that only measures at a single frequency point or within a narrow frequency band range, this method significantly improves the perception accuracy of the complex dielectric behavior of non-linear materials and effectively avoids the problem of underestimating or missing the influence of the electric double layer due to improper frequency selection.

[0030] The present invention uses the Spearman rank correlation coefficient to quantitatively evaluate the dependence relationship between the dielectric constant of a specimen and its thickness, providing a criterion for judging whether the thickness effect is significant from a statistical perspective. Compared with the traditional methods that rely on manual trend judgment or rough linear fitting, the Spearman coefficient can handle non-linear relationships and non-normal distribution data, improving the stability and reliability of the analysis results and avoiding the risk of misjudgment caused by subjective human judgment.

[0031] After finding an obvious correlation between the dielectric constant and the thickness, the present invention further uses the mathematical relationship derived from the equivalent circuit model to perform non-linear fitting on the measurement data, thereby inversely calculating the true dielectric constant of the material that is not affected by the thickness. Compared with the methods of simply normalizing or averaging the thickness in existing research, this method has a more physical basis and mathematical rigor, can significantly improve the measurement accuracy of the dielectric constant, and reduce the risk brought by parameter errors in material selection and insulation structure design.

[0032] Overall, the method of the present invention introduces refined and quantifiable processing means in three key aspects: identifying the effect of the electric double layer, evaluating the thickness effect, and extracting the true parameters, systematically solving the problem of the change of the dielectric constant of non-linear insulating media with thickness. Compared with the existing technical means that rely on empirical judgment and simplified models, it has higher adaptability, accuracy, and theoretical depth, providing a solid foundation for the precise characterization and engineering application of high-performance insulating materials.

[0033] It can be applied to the precise measurement of the dielectric properties of non-linear insulating materials and the analysis of insulation structure design. Description of the Drawings

[0034] Figure 1 Equivalent circuit for the measurement results of the capacitance of non-linear composite dielectrics considering the effect of the electric double layer;

[0035] Figure 2 Comparison of the conductivity of SiC / EP non-linear dielectrics and LDPE dielectrics under an electric field of 5 kV / mm;

[0036] Figure 3 Relationship curve between the relative dielectric constant and frequency of LDPE dielectrics with different thicknesses;

[0037] Figure 4 Relationship between the relative dielectric constant of LDPE at the characteristic frequency and the thickness;

[0038] Figure 5 Relationship curve between the relative dielectric constant and frequency of SiC / EP non-linear dielectrics with different thicknesses;

[0039] Figure 6Relationship curve and fitting curve of relative permittivity of SiC / EP nonlinear medium at characteristic frequency with thickness. Specific implementation mode

[0040] To make the advantages and beneficial effects of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention will be further described in detail with reference to the accompanying drawings. Specifically:

[0041] Embodiment 1. This embodiment provides a method for accurately measuring the permittivity of a nonlinear insulating medium, including:

[0042] Steps of constructing an equivalent circuit model;

[0043] Steps of collecting measured values of permittivity of specimens with different thicknesses, using a broadband dielectric spectrometer to test the relative permittivity of specimens with different thicknesses at multiple frequency points, and obtaining data of permittivity varying with thickness;

[0044] Steps of judging whether the permittivity has thickness dependence based on the data of permittivity varying with thickness;

[0045] If it has thickness dependence, substituting the measured value of permittivity into the equivalent circuit model for nonlinear fitting, and extracting the true permittivity value of the material;

[0046] Steps of outputting the true permittivity.

[0047] In the equivalent circuit model, the measured capacitance of the nonlinear insulating medium to be measured is represented by a circuit model composed of the Stern layer capacitance, the diffusion layer capacitance, and the specimen bulk capacitance connected in series.

[0048] Using the Spearman rank correlation coefficient to analyze the correlation between the relative permittivity and the specimen thickness, and judging whether the permittivity has thickness dependence.

[0049] The measurement frequency range of the broadband dielectric spectrometer is from 0.1 Hz to 1 MHz.

[0050] The nonlinear fitting uses the nonlinear least squares method for parameter fitting, and the fitting variables include two equivalent capacitance values in the electric double layer and the true permittivity of the material.

[0051] The multiple frequency points include representative frequencies in the low frequency band, the middle frequency band, and the high frequency band.

[0052] Embodiment 2. This embodiment is a further description of the technical solution provided in Embodiment 1. Specifically:

[0053] Step 1: Construct an equivalent circuit model considering the electric double layer

[0054] First, construct an equivalent circuit model that can truly reflect the electrical behavior of the nonlinear insulating medium during the dielectric constant measurement. Specifically, the total capacitance of the specimen is considered to be composed of three parts in series, namely the Stern layer capacitance near the electrode surface, the diffusion layer capacitance outside the Stern layer, and the bulk capacitance of the specimen. Since the thickness of the electric double layer is negligible compared to the specimen thickness, the true dielectric constant of the specimen is directly proportional to its bulk capacitance. This equivalent model provides a theoretical basis for subsequent thickness correlation analysis and true dielectric constant extraction.

[0055] Step 2: Measure the dielectric constants of specimens with different thicknesses

[0056] Next, prepare a group of specimens of nonlinear insulating media with different thicknesses. For example, use an epoxy resin composite doped with 15% silicon carbide as the test object. Measure the dielectric constants of specimens with different thicknesses using a broadband dielectric spectrometer. The measurement frequency range is set between 0.1 Hz and 1 MHz, and the test voltage is 1 V. For each specimen, record the relative dielectric constant change curve over the entire frequency range to obtain complete dielectric response information.

[0057] Step 3: Analyze the correlation between the dielectric constant and the specimen thickness

[0058] After obtaining the dielectric constant data of each specimen, select three representative frequency points, located in the low-frequency band, mid-frequency band, and high-frequency band respectively, such as 0.4 Hz, 1195.2 Hz, and 714290 Hz. For each frequency point, extract the corresponding dielectric constant data and perform statistical analysis using the Spearman rank correlation coefficient to determine whether the dielectric constant changes significantly with the specimen thickness. If the correlation coefficient is high, it indicates that there is a significant correlation between the dielectric constant measurement result and the thickness; otherwise, it can be considered that the thickness has little effect on the result.

[0059] Step 4: Process according to the correlation results

[0060] If the analysis results show that there is no correlation between the dielectric constant and the thickness, it can be considered that the electric double layer does not significantly interfere with the measurement, and the test results are reliable. The average value of the measurement values with different thicknesses can be directly taken as the final dielectric constant. If the analysis results show that the dielectric constant changes significantly with the thickness, a fitting analysis needs to be performed based on the equivalent circuit model to exclude the influence of the electric double layer.

[0061] Step 5: Perform fitting and extract the true dielectric constant

[0062] Substitute the thickness data of the specimen and the measured dielectric constant data into the mathematical expression of the equivalent circuit, and use the non-linear fitting method to inversely deduce the three series capacitor parameters, and finally obtain the true dielectric constant of the specimen. During the fitting process, the effective area of the electrode and the vacuum dielectric constant are known constants, the specimen thickness and the measured value are input data, and the two capacitance parameters in the electric double layer and the true dielectric constant of the material are the fitting output variables. The finally obtained true dielectric constant is not affected by the thickness change and can truly reflect the intrinsic characteristics of the material.

[0063] Step Six: Verify the effectiveness of the method and apply the results

[0064] To verify the effectiveness of this method, pure low-density polyethylene (LDPE) with extremely low conductivity was used as a control group for the same measurement and analysis. It was found that there was no obvious correlation between its dielectric constant and thickness, confirming that the electric double layer in this material was not obvious. This method is applicable to non-linear dielectrics with relatively high conductivity such as SiC / EP, can effectively eliminate the interference caused by thickness errors, extract the true dielectric parameters, and provide a reliable basis for subsequent insulation performance evaluation, electric field regulation material optimization, and electrical equipment structure design.

[0065] Embodiment Three: Combination Figure 1-6 This embodiment will further describe the above-provided technical solution in detail through specific examples. Specifically:

[0066] In Figure 1 In the equivalent circuit of the measurement result of the non-linear composite dielectric capacitor considering the influence of the electric double layer shown, the experimental measurement result C of the relative dielectric constant of the specimen to be tested is actually the equivalent capacitance C1 of the Stern layer or Helmholtz layer that constitutes the electric double layer, the equivalent capacitance C2 of the diffusion layer, and the true capacitance C of the specimen r in series. Therefore, it can be known that:

[0067]

[0068] Since the thickness d of the electric double layer can be ignored compared with the thickness of the specimen to be tested, the true capacitance C of the specimen to be tested r The relationship with the true relative dielectric constant ε is:

[0069]

[0070] In the formula: ε is the vacuum dielectric constant, ε = 8.85×10 -12 F / m; e r is the true dielectric constant of the specimen; S is the effective area of the measurement electrode; d is the thickness of the specimen.

[0071] Substituting Equation (2) into Equation (1) gives:

[0072]

[0073] where: ε′ is the measurement result of the relative dielectric constant of the specimen.

[0074] When the electrodes used in the test process are determined, the effective area S of the measurement electrode is a constant, and the unknowns in Equation (3) are only C1, C2, and ε. Therefore, the true dielectric constant ε of the specimen to be tested can be obtained by fitting the relationship curve between the measured dielectric constant and the thickness.

[0075] The relative dielectric constants of specimens to be tested with different thicknesses are measured using a broadband dielectric spectrometer to obtain the relationship curve between the relative dielectric constant and the frequency of specimens with different thicknesses. The measurement frequency band is divided into a low-frequency band, a medium-frequency band, and a high-frequency band (relatively), and the relationship between the relative dielectric constant and the thickness is extracted in the low-frequency band, the medium-frequency band, and the high-frequency band respectively, as Figure 4 or Figure 6 shown. The Spearman correlation coefficient is used to evaluate the dependence relationship between the relative dielectric constant and the thickness. The calculation formula for the Spearman correlation coefficient is:

[0076]

[0077] where: r is the Spearman correlation coefficient; n is the number of data points; d is the rank difference of the data points of the two variables.

[0078] The value range of the correlation coefficient r is between -1 and 1. When r > 0, it indicates that the two variables change proportionally; when r < 0, it indicates that the two variables change inversely. If the value of |r| is closer to 1, it indicates that the correlation between the two variables is stronger. When it is between 0.8 and 1, it indicates that the correlation between the two variables is strong; between 0.6 and 0.8, it indicates that the correlation between the two variables is strong; between 0.4 and 0.6, it indicates that the correlation between the two variables is moderate; between 0.2 and 0.4, it indicates that the degree of correlation between the two variables is low; between 0 and 0.2, it indicates that the degree of association between the two variables is extremely low and can be regarded as irrelevant.

[0079] First, perform a Spearman correlation analysis on the measurement results of the relative dielectric constant of the specimen at a specific frequency, and judge whether the measurement result of the dielectric constant is related to the specimen thickness according to the correlation result. If the correlation result shows that there is no dependence relationship between the measurement result of the dielectric constant of the specimen and the thickness, there is no need to process the measurement result of the dielectric constant. The fluctuation of the measurement result may be due to measurement error, and taking the average value is sufficient; if the correlation result shows that there is an obvious coherence between the measurement result of the dielectric constant and the thickness, then Equation (3) needs to be used to fit the measurement result to obtain the true dielectric constant of the specimen.

[0080] The insulating dielectrics in this embodiment are 15wt% silicon carbide / epoxy resin (SiC / EP) nonlinear insulating dielectric and pure low-density polyethylene (LDPE) insulating dielectric respectively, and the effective measurement area S of the electrode is 314 mm 2 , the measurement voltage of the broadband dielectric spectrometer is 1 V, and the measurement frequency range is 10 -1 ~10 6 Hz.

[0081] Figure 2 is the conduction current density of the SiC / EP nonlinear insulating dielectric and the LDPE insulating dielectric under an electric field of 5 kV / mm. It can be found from Figure 2 that the conductivity of the LDPE dielectric is at least 6 orders of magnitude lower than that of the SiC / EP nonlinear insulating dielectric, which means that the number of carriers in the LDPE is extremely small, and the electric double layer is less likely to be established when measuring the dielectric constant.

[0082] The measurement results of the relative dielectric constants of the SiC / EP nonlinear insulating dielectric and the LDPE insulating dielectric with different thicknesses are respectively as Figure 3 、 Figure 5 shown.

[0083] The measurement results of the relative dielectric constants of the specimens with different thicknesses corresponding to the frequencies of 0.4 Hz, 1195.2 Hz, and 714290 Hz are taken in the low-frequency band, the medium-frequency band, and the high-frequency band respectively, as Figure 4 、 Figure 6 shown.

[0084] First, calculate the Spearman correlation coefficients between the measurement results of the dielectric constants of the two materials and the thickness. The results are shown in Table 1, the Spearman correlation coefficients between the measurement results of the relative dielectric constants of the LDPE insulating dielectric at different frequencies and the specimen thickness, and Table 2, the Spearman correlation coefficients between the measurement results of the relative dielectric constants of the SiC / EP nonlinear insulating dielectric at different frequencies and the specimen thickness.

[0085] Table 1

[0086] Frequency / Hz Spearman correlation coefficient 0.4 0.441 1195.2 0.441 714290 0.441

[0087] Table 2

[0088] Frequency / Hz Spearman correlation coefficient 0.4 0.720 1195.2 0.678 714290 0.776

[0089] Referring to the critical value table of Spearman rank correlation coefficient test, it can be found that: the Spearman correlation coefficients between the relative permittivity measurement results of LDPE insulating medium at different frequencies and the sample thickness are all less than 0.587, indicating that the Spearman rank correlation is not significant, that is, there is no significant correlation between the two variables. Therefore, there is no need to use the fitting method proposed in the present invention for processing. For the SiC / EP nonlinear insulating medium, the Spearman correlation coefficients between the relative permittivity measurement results at different frequencies and the sample thickness are all greater than 0.587, indicating that there is a significant positive correlation between them. As the sample thickness increases, the measured relative permittivity of the sample also increases. Therefore, the obtained relative permittivity measurement results cannot truly reflect the true permittivity of the medium.

[0090] According to Equation (3), the relationship curve between the relative permittivity measurement results of the SiC / EP nonlinear insulating medium and the thickness is fitted, and the fitting results are as Figure 6 shown. The specific parameters are as shown in Table 3, which shows the Spearman correlation coefficients between the relative permittivity measurement results of the SiC / EP nonlinear insulating medium at different frequencies and the sample thickness.

[0091] Table 3

[0092]

[0093] The above further describes the technical solutions provided by the present invention in several specific embodiments to highlight the advantages and beneficial effects of the technical solutions provided by the present invention. However, the above several specific embodiments are not used as limitations on the present invention. Any reasonable modifications, improvements, combinations of embodiments, and equivalent replacements based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for accurately measuring the dielectric constant of a non-linear insulating medium, characterized in that, Including: Steps for constructing an equivalent circuit model; Steps for collecting measured values of the dielectric constant of specimens with different thicknesses, using a broadband dielectric spectrometer to test the relative dielectric constant of specimens with different thicknesses at multiple frequency points, and obtaining data on the variation of the dielectric constant with thickness; Steps for judging whether the dielectric constant has thickness dependence based on the data of the variation of the dielectric constant with thickness; If there is thickness dependence, substituting the measured values of the dielectric constant into the equivalent circuit model for nonlinear fitting to extract the true dielectric constant value of the material; Steps for outputting the true dielectric constant.

2. The method for accurately measuring the dielectric constant of a non-linear insulating medium according to claim 1, characterized in that, In the equivalent circuit model, the measured capacitance of the nonlinear insulating medium to be measured is represented by a circuit model composed of a Stern layer capacitance, a diffusion layer capacitance, and a specimen bulk capacitance connected in series.

3. A method for accurately measuring the dielectric constant of a non-linear insulating medium according to claim 1, characterized in that Using the Spearman rank correlation coefficient to analyze the correlation between the relative dielectric constant and the specimen thickness, and judging whether the dielectric constant has thickness dependence.

4. A method for accurately measuring the dielectric constant of a non-linear insulating medium according to claim 1, characterized in that, The measurement frequency range of the broadband dielectric spectrometer is from 0.1 Hz to 1 MHz.

5. A method for accurately measuring the dielectric constant of a non-linear insulating medium according to claim 1, characterized in that The nonlinear fitting is performed using the nonlinear least squares method for parameter fitting, and the fitting variables include two equivalent capacitance values in the electric double layer and the true dielectric constant of the material.

6. A method for accurately measuring the dielectric constant of a non-linear insulating medium according to claim 1, characterized in that, The multiple frequency points include representative frequencies in the low-frequency band, the middle-frequency band, and the high-frequency band.

7. An apparatus for accurately measuring the dielectric constant of a non-linear insulating medium, characterized in that, Including: A module for constructing an equivalent circuit model; A module for collecting measured values of the dielectric constant of specimens with different thicknesses, using a broadband dielectric spectrometer to test the relative dielectric constant of specimens with different thicknesses at multiple frequency points, and obtaining data on the variation of the dielectric constant with thickness; A module for judging whether the dielectric constant has thickness dependence based on the data of the variation of the dielectric constant with thickness; If there is thickness dependence, a module for substituting the measured values of the dielectric constant into the equivalent circuit model for nonlinear fitting to extract the true dielectric constant value of the material; A module for outputting the true dielectric constant.

8. A computer storage medium for storing a computer program, characterized in that, When the computer program is read by a computer, the computer executes the method described in claim 1.

9. A computer, comprising a processor and a storage medium, characterized in that, When the processor reads the computer program stored in the storage medium, the computer executes the method described in claim 1.

10. A computer program product, as a computer program, characterized in that, When the computer program is executed, the method described in claim 1 is implemented.

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