CN116930274A - Moisture capacitance tomography calibration device and method for wood structure by medium substitution method - Google Patents
Moisture capacitance tomography calibration device and method for wood structure by medium substitution method Download PDFInfo
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- 239000002023 wood Substances 0.000 title claims abstract description 109
- 238000000034 method Methods 0.000 title claims abstract description 51
- 238000003325 tomography Methods 0.000 title claims abstract description 26
- 238000006467 substitution reaction Methods 0.000 title claims abstract description 23
- 239000002245 particle Substances 0.000 claims abstract description 65
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 50
- 238000005070 sampling Methods 0.000 claims abstract description 27
- 238000001035 drying Methods 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 7
- 230000005284 excitation Effects 0.000 claims description 17
- 239000003990 capacitor Substances 0.000 claims description 12
- 238000005259 measurement Methods 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 6
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- 230000001105 regulatory effect Effects 0.000 claims description 6
- 241001270131 Agaricus moelleri Species 0.000 claims description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
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- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims 1
- 238000003384 imaging method Methods 0.000 description 11
- 239000007787 solid Substances 0.000 description 3
- 230000005514 two-phase flow Effects 0.000 description 3
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- 230000000704 physical effect Effects 0.000 description 1
- 208000005687 scabies Diseases 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
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Abstract
The application discloses a moisture capacitance tomography calibration device and method for a wood structure by a medium substitution method. Aiming at the problem that the conventional two-point type hollow/full pipe calibration mode cannot be adopted for calibration due to uneven dielectric constant distribution caused by unstable factors such as wood structure texture structures, hollows, wood knots and the like, a medium substitution method is provided. The method comprises the steps of adopting a 2-electrode sampling capacitance sensor to sample wood strips with different water contents, simultaneously using a drying method to measure the real water contents, establishing the distribution relation of the water contents and the capacitance of the sampling capacitance sensor, and uniformly mixing two different dielectric constant particles to form any dielectric constant medium with a substituted wood structure, so as to realize the calibration of the air/full tube capacitance of the capacitance tomography system, and finally establishing the relation between the gray level of an image and the water contents. The application solves the problems of difficult calibration and inaccurate calibration of the non-uniform dielectric capacitance tomography.
Description
Technical Field
The application relates to the technical field of capacitance tomography, in particular to a moisture capacitance tomography calibration device and method for a wood structure by a medium substitution method.
Background
The capacitance tomography (Electrical Capacitance Tomography, abbreviated as ECT) measures the capacitance between electrodes arranged in the outline of an imaging area, reconstructs the dielectric constant distribution of the imaging area according to the sensor sensitivity field characteristics and an inversion algorithm, can realize non-contact imaging of the dielectric constant inside any structure, and is an ideal non-contact measurement technology. The typical two-dimensional ECT has n capacitor electrode arrays arranged along the circumferential direction outside the circular insulating rigid pipe, a capacitor is formed between every 2 electrodes, m=n (n-1)/2 capacitor arrays C are all formed, the size of the m capacitors is closely related to the distribution of the dielectric constants in the pipe, the in-pipe sensitive field S with the relation between the dielectric constants and the array capacitors is obtained by modeling the sensing characteristics in the pipe, and the distribution of the dielectric constants in the pipe is reconstructed according to the sensitive field S, the n array capacitors and a certain inversion algorithm.
In the measurement process, the two-phase flow mixed dielectric constant change caused by the solid material type change or the physical property change can cause the error of the normalized capacitance to influence the imaging effect, so that the medium is required to be calibrated. In the normal calibration process, the capacitance tomography sensor is generally detached and placed in 2 states of empty pipe and full pipe to collect the data of the empty pipe capacitance and the full pipe capacitance, namely a two-point calibration method, which is also called empty and full pipe calibration. Taking gas-solid two-phase flow as an example, firstly, emptying an imaging area to obtain a sensor capacitor under an empty pipe, and obtaining a state that the gray level of the imaging area is 0, which is called empty pipe calibration; and secondly, filling the imaging area with a measured medium to obtain a full-tube sensor capacitor, and obtaining a state that the gray level of the imaging area is 1, which is called full-tube calibration.
For uniform and stable mediums such as gas-solid particle flow, gas-liquid flow, liquid-solid flow and other two-phase flow, a two-point calibration method of capacitance tomography is quite mature, in imaging of moisture content distribution of a wood structure, as moisture content of the wood structure is greatly influenced by environment, meanwhile, the variety, texture, scabies and the like of the wood structure also cause uneven dielectric constant distribution, 0 and 1 corresponding to gray scale cannot be found or manufactured by using uniform and known stable wood with uniform moisture content, and in the calibration process, the relationship between gray scale and moisture content of an image is found to be nonlinear, if a conventional calibration method is adopted, nonlinear errors are brought, and the further from the two calibration points, the nonlinear errors of the moisture content are larger. Therefore, the existing mature empty/full pipe calibration method cannot be adopted for calibration.
Disclosure of Invention
1. The technical problems to be solved are as follows:
aiming at the technical problems, the application provides a moisture capacitance tomography calibration device and a moisture capacitance tomography calibration method for a wood structure by a medium substitution method, which adopts a medium substitution method to mix two uniform particles with different dielectric constants to form particles with any dielectric constant for replacing the wood structure, so as to solve the problems of difficult calibration and inaccurate calibration of uneven medium; in the scheme, the water content and capacitance relation of a certain wood species is obtained by using the sampling capacitance sensor and square wood strip samples with different water contents, so that the indexing relation of the water content and the sampling capacitance is formed and used for ECT calibration by a medium substitution method.
2. The technical scheme is as follows:
the moisture capacitance tomography calibration device of the wood structure by a medium substitution method is used for realizing the calibration of the moisture content distribution of the wood structure; the device comprises mixed calibration particles, a plurality of sample wood strips with different water contents and a two-electrode sampling capacitance sensor device; the mixed calibration particles are formed by mixing two particles with high dielectric constant and low dielectric constant, and the overall equivalent dielectric constant of the mixed calibration particles can be changed by adjusting the proportion of the two particles;
the two-electrode sampling capacitance sensor device comprises a measuring electrode plate and an exciting electrode plate; the measuring electrode plate comprises a sheet measuring electrode and a grounding annular protecting electrode which surrounds the periphery of the measuring electrode with a gap; the measuring electrode plate and the exciting electrode plate are oppositely arranged, and a cavity between the measuring electrode plate and the exciting electrode plate is used as a measuring area which is slightly larger than the sample wood strip and is used for placing the sample wood strip or filling mixed calibration particles; the excitation electrode is connected with the excitation signal generator to generate an excitation alternating voltage signal, so that a uniform alternating electric field can be generated in a measurement area.
Further, the exciting electrode and the measuring electrode are rectangular copper foils; the whole size of the measuring electrode and the grounding annular protective electrode surrounding the measuring electrode is the same as the shape and the size of the exciting electrode; the cross section of the sample wood strip is square; the measuring area between the measuring electrode plate and the exciting electrode plate is cuboid.
Further, the excitation electrode and the measurement electrode are rectangular stainless steel sheets; the whole size of the measuring electrode and the grounding annular protective electrode surrounding the measuring electrode is the same as the shape and the size of the exciting electrode; the measuring area between the measuring electrode plate and the exciting electrode plate is cuboid.
Further, the excitation electrode is twice as long as it is wide.
Further, the side length of the sample wood strip is 15-30mm; the length of the exciting electrode is 50-100mm, and the width of the exciting electrode is 30-50mm.
Further, the particles of the mixed calibration particles are mixed by a high-dielectric-constant particle material with a relative dielectric constant greater than 15 and a low-dielectric-constant particle material with a relative dielectric constant less than 4.
A moisture capacitance tomography calibration method of a wood structure by a medium substitution method comprises the following steps:
step one: the sample battens with at least 5 different water contents are preset, so that the common water content measuring range can be uniformly covered.
Step two: the sample wood strips with different water contents are respectively placed in a measuring area in a calibration device to measure the corresponding capacitance value Cs, and simultaneously the corresponding sample wood strips are weighed to obtain the weight of the corresponding sample wood stripsm w 。
Step three: obtaining the weight m of each sample wood strip under absolute dryness by adopting a drying method 0 The method comprises the steps of carrying out a first treatment on the surface of the Drying the wood strips in an oven at 103 ℃ to remove water, and continuously monitoring the weight change; when the weight change is smaller than the preset weight difference in the preset time period, the sample wood strip is considered to be in an absolute dry state, and the weight of the wood block is the absolute dry weight of the sample wood stripm 0 The method comprises the steps of carrying out a first treatment on the surface of the Each sample is subjected toThe weight and absolute dry weight of the wood strip are brought into the formula: mc= (m w - m 0 )/ m 0 And calculating the real water content MC of the corresponding sample wood strip.
Step four: and (3) inputting the water content MC of the sample wood strip obtained in the step (III) into a computer to fit a relation curve corresponding to the capacitance value Cs measured in the step (II), and obtaining the MC-Cs graduation table of the wood.
Step five: the ratio of the two calibration particles is regulated to form a preset mixed calibration particle with low dielectric constant, and the mixed calibration particle is filled in a measuring area of the sampling capacitance sensor to measure the capacitance Cs l Then, looking up the index table in the fourth step to obtain the corresponding moisture MC l Meanwhile, the mixed particles are used for calibrating the empty tube of ECT to obtain the empty tube capacitor with the corresponding ECT image gray level of 0; the ratio of the two particles is regulated to form a preset mixed calibration particle h with high dielectric constant, and the mixed calibration particle h is filled in a sampling capacitance sensor to measure the capacitance Cs of the sampling capacitance sensor h Then checking the index table of MC-Cs of the wood in the fourth step to obtain the corresponding moisture MC h And simultaneously, the mixed particles are used for full tube calibration of ECT, so that the full tube capacitance with the corresponding ECT image gray level of 1 is obtained.
Step six: reconstructing a gray image according to the ECT calibrated in the fifth step, and converting the gray of the image into a water content graduation table according to the gray and water content relation in the fifth step.
Further, the sixth step is specifically: replacing the coordinate axis representing the capacitance value in the MC-Cs graduation table of the wood with a gray coordinate axis, wherein the coordinate axis representing the moisture is unchanged; based on the empty-full tube calibration result in the fifth step, two points with corresponding gray scales of 0 and 1 in the relation curve are found; dividing equally between the two points with the gray level of 0 and 1, and converting the MC-Cs graduation table of the wood into an MC-g graduation table.
Further, in the first step, the water content distribution range of the similar sample wood strips with 5 different water contents is 15% -50%, and the difference of the water contents is more than 5%.
3. The beneficial effects are that:
(1) According to the scheme, aiming at the current situation that the conventional two-point type hollow full pipe calibration mode cannot be adopted for calibration due to the fact that the internal water content is uneven due to the influences of unstable factors such as a wood structure texture structure, hollows and wood knots, the internal water content is uneven, and the conventional two-point type hollow full pipe calibration mode cannot be adopted, a medium substitution method is adopted, any dielectric constant substance for replacing a wood structure is formed by uniformly mixing two different dielectric constant particles, and the problems of difficulty in calibrating and inaccuracy in calibrating uneven medium are solved.
(2) In the scheme, the sampling capacitance sensor device for calibration is designed, and the moisture and capacitance relation of a certain wood species is obtained through square wood strip samples with different moisture contents which are suitable for the sampling capacitance sensor, so that the indexing relation of the moisture content and the sampling capacitance is formed, and the sampling capacitance sensor device is used for ECT calibration by a medium substitution method. The device has the advantages of simple structure, small size, easy realization and non-contact type absolute water content calibration.
(3) In the scheme, the mode of adjusting the proportion of the two particles is adopted, so that ECT calibration is realized by replacing a non-uniform wood structure with particles with uniform dielectric constant distribution, the random adjustment of an imaging water content interval can be achieved, and the calibration problem of ECT imaging of moisture of the wood structure is solved.
Drawings
FIG. 1 is a schematic diagram of a measuring electrode of a calibration device of the present application;
FIG. 2 is a schematic illustration of the excitation electrode of the calibration device of the present application;
FIG. 3 is a cross-sectional view of a calibration device according to the present application;
FIG. 4 is an index table of MC-Cs in an embodiment;
fig. 5 is a schematic diagram of an alternative method in this embodiment.
Reference numerals: measuring an electrode plate 1; a sheet-like measuring electrode 11; a ground ring guard electrode 12; a gap 13 between the sheet-like measuring electrode and the guard electrode; the electrode plate 2 is excited.
Detailed Description
The present application will be described in detail with reference to the accompanying drawings.
As shown in fig. 1-3, a moisture capacitance tomography calibration device of a wood structure by a medium substitution method is used for realizing the calibration of the moisture content distribution of the wood structure; the device comprises mixed calibration particles, a plurality of sample battens with different water contents and a two-electrode sampling capacitance sensor device; the mixed calibration particles are formed by mixing two particles with high dielectric constant and low dielectric constant, and the overall equivalent dielectric constant of the mixed calibration particles can be changed by adjusting the proportion of the two particles.
The two-electrode sampling capacitance sensor device comprises a measuring electrode plate 1 and an exciting electrode plate 2; the measuring electrode plate comprises a sheet measuring electrode 11 and a grounding annular protecting electrode 12 which surrounds the periphery of the measuring electrode with gaps; the measuring electrode plate and the exciting electrode plate are oppositely arranged, a cavity between the measuring electrode plate and the exciting electrode plate is used as a measuring area, and the measuring area is slightly larger than the sample wood strip and is used for placing the sample wood strip or filling mixed calibration particles; the excitation electrode is connected with the excitation signal generator to generate an excitation alternating voltage signal, so that a uniform alternating electric field can be generated in a measurement area.
Further, the exciting electrode and the measuring electrode are rectangular copper foils; the whole size of the measuring electrode and the grounding annular protective electrode surrounding the measuring electrode is the same as the shape and the size of the exciting electrode; the cross section of the sample wood strip is square; the measuring area between the measuring electrode plate and the exciting electrode plate is cuboid.
As shown in fig. 1, 13 denotes a gap between the sheet-like measuring electrode and the ground ring guard electrode.
Further, the excitation electrode and the measurement electrode are rectangular stainless steel sheets; the whole size of the measuring electrode and the grounding annular protective electrode surrounding the measuring electrode is the same as the shape and the size of the exciting electrode; the measuring area between the measuring electrode plate and the exciting electrode plate is cuboid.
Further, the excitation electrode is twice as long as it is wide.
Further, the side length of the sample wood strip is 15-30mm; the length of the exciting electrode is 50-100mm, and the width of the exciting electrode is 30-50mm.
Further, the particles of the mixed calibration particles are mixed by a high-dielectric-constant particle material with a relative dielectric constant greater than 15 and a low-dielectric-constant particle material with a relative dielectric constant less than 4.
A moisture capacitance tomography calibration method of a wood structure by a medium substitution method comprises the following steps:
step one: presetting at least 5 sample wood strips with different water contents, and uniformly covering a common water content measuring range;
step two: the sample wood strips with different water contents are respectively placed in a measuring area in a calibration device to measure the corresponding capacitance value Cs, and simultaneously the corresponding sample wood strips are weighed to obtain the weight of the corresponding sample wood stripsm w 。
Step three: obtaining the weight m of each sample wood strip under absolute dryness by adopting a drying method 0 The method comprises the steps of carrying out a first treatment on the surface of the Drying the wood strips in an oven at 103 ℃ to remove water, and continuously monitoring the weight change; when the weight change is smaller than the preset weight difference in the preset time period, the sample wood strip is considered to be in an absolute dry state, and the weight of the wood block at the moment is the absolute dry weight of the sample wood stripm 0 The method comprises the steps of carrying out a first treatment on the surface of the The weight and absolute weight of each sample stick were taken into the formula: mc= (m w - m 0 )/ m 0 And calculating the real water content MC of the corresponding sample wood strip.
Step four: and (3) inputting the water content MC of the sample wood strip obtained in the step (III) into a computer to fit a relation curve corresponding to the capacitance value Cs measured in the step (II), and obtaining the MC-Cs graduation table of the wood.
Step five: the ratio of the two calibration particles is regulated to form a preset mixed calibration particle with low dielectric constant, and the mixed calibration particle is filled in a measuring area of the sampling capacitance sensor to measure the capacitance Cs l Then, looking up the index table in the fourth step to obtain the corresponding moisture MC l Meanwhile, the mixed particles are used for calibrating the empty tube of ECT to obtain the empty tube capacitor with the corresponding ECT image gray level of 0; the ratio of the two particles is regulated to form a preset mixed calibration particle h with high dielectric constant, and the mixed calibration particle h is filled in a sampling capacitance sensor to measure the capacitance Cs of the sampling capacitance sensor h Then, checking the graduation table of the wood MC-Cs in the fourth step to obtain the corresponding moisture MC h And simultaneously, the mixed particles are used for full tube calibration of ECT, so that the full tube capacitance with the corresponding ECT image gray level of 1 is obtained.
Step six: reconstructing a gray image according to the ECT calibrated in the fifth step, and converting the gray of the image into a water content graduation table according to the gray and water content relation in the fifth step.
Further, the sixth step is specifically: replacing the coordinate axis representing the capacitance value in the MC-Cs graduation table of the wood with a gray coordinate axis, wherein the coordinate axis representing the moisture is unchanged; based on the empty-full tube calibration result in the fifth step, two points with corresponding gray scales of 0 and 1 in the relation curve are found; dividing equally between the two points with the gray level of 0 and 1, and converting the MC-Cs graduation table of the wood into an MC-g graduation table.
Further, in the first step, the water content distribution range of the similar sample wood strips with 5 different water contents is 15% -50%, and the difference of the water contents is more than 5%.
Specific examples:
in the embodiment, the wood with different water contents for calibration is manufactured by taking the water contents of about 15%, 20%, 30%, 40%, 50% and the like as expected targets as sample wood strips; the wood strips are similar in size, and the cross section of the wood strips is 20mmX20mm; by adopting the scheme, the corresponding data of the moisture content MC of the wood strip and the capacitance Cs of the sampling sensor shown in figure 4 are obtained, and a relation curve of the corresponding data and the corresponding data is fitted to form a graduation table of the relation of the moisture content MC of the wood strip and the capacitance Cs of the sampling sensor.
Replacing the low-water-content wood strips with mixed particles with low equivalent dielectric constants, and calibrating the low dielectric constants of the ECT system to obtain an empty pipe capacitor Cl; mixing to form mixed particles with high equivalent dielectric constant, sampling and measuring the capacitance value of the mixed particles, adjusting the mixing proportion to form particles with the capacitance equal to that of the wood with expected high water content, and calibrating ECT high dielectric constant medium to obtain full-pipe capacitance Ch. And normalizing the capacitance and calculating the image gray according to an image reconstruction algorithm. Cl corresponds to the gray level of the image to be 0; the image gray corresponding to Ch is 1; the curve between gray 0 and 1 is the relationship line between the moisture content of the wood and the gray, thereby completing the calibration of the ECT system. Fig. 5 is a graph reflecting the conversion relation between the parameters in the present embodiment.
While the application has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the application, and it is intended that the scope of the application shall be defined by the appended claims.
Claims (9)
1. The moisture capacitance tomography calibration device of the wood structure by the medium substitution method is used for realizing the calibration of the moisture content distribution of the wood structure; the method is characterized in that: the device comprises mixed calibration particles, a plurality of sample battens with different water contents and a two-electrode sampling capacitance sensor device; the mixed calibration particles are formed by mixing two particles with high dielectric constant and low dielectric constant, and the whole equivalent dielectric constant of the calibration mixed particles can be changed by adjusting the proportion of the two particles;
the two-electrode sampling capacitance sensor device comprises a measuring electrode plate and an exciting electrode plate; the measuring electrode plate comprises a sheet measuring electrode and a grounding annular protecting electrode which surrounds the periphery of the measuring electrode with a gap; the measuring electrode plate and the exciting electrode plate are oppositely arranged, and a cavity between the measuring electrode plate and the exciting electrode plate is used as a measuring area which is slightly larger than the sample wood strip and is used for placing the sample wood strip or filling mixed calibration particles; the excitation electrode is connected with the excitation signal generator to generate an excitation alternating voltage signal, so that a uniform alternating electric field can be generated in a measurement area.
2. The device for calibrating moisture capacitance tomography of a wood structure by a medium substitution method according to claim 1, wherein the device is characterized in that: the excitation electrode and the measurement electrode are rectangular copper foils; the whole size of the measuring electrode and the grounding annular protective electrode surrounding the measuring electrode is the same as the shape and the size of the exciting electrode; the cross section of the sample wood strip is square; the measuring area between the measuring electrode plate and the exciting electrode plate is cuboid.
3. The device for calibrating moisture capacitance tomography of a wood structure by a medium substitution method according to claim 1, wherein the device is characterized in that: the excitation electrode and the measurement electrode are rectangular stainless steel sheets; the whole size of the measuring electrode and the grounding annular protective electrode surrounding the measuring electrode is the same as the shape and the size of the exciting electrode; the measuring area between the measuring electrode plate and the exciting electrode plate is cuboid.
4. A moisture capacitance tomography calibration apparatus for a media substitution method wood structure according to claim 2 or 3, characterized in that: the excitation electrode is twice as long as it is wide.
5. A moisture capacitance tomography calibration apparatus for a media substitution method wood structure according to claim 2 or 3, characterized in that: the side length of the sample wood strip is 15-30mm; the length of the exciting electrode is 50-100mm, and the width of the exciting electrode is 30-50mm.
6. The moisture capacitance tomography calibration apparatus of a media substitution method wood structure according to claim 1, wherein: the particles of the mixed calibration particles are mixed by a high-dielectric-constant particle material with a relative dielectric constant greater than 15 and a low-dielectric-constant particle material with a relative dielectric constant less than 4.
7. A moisture capacitance tomography calibration method of a wood structure by a medium substitution method, which adopts the device as set forth in any one of claims 1-6; the method is characterized in that: the method comprises the following steps:
step one: presetting at least 5 sample wood strips with different water contents, and uniformly covering a common water content measuring range;
step two: the sample wood strips with different water contents are respectively placed in the measuring areas of the sampling capacitance sensor to measure the corresponding capacitance value Cs, and simultaneously the corresponding weight of the sample wood strips is obtained by weighing the sample wood stripsm w ；
Step three: obtaining the weight m of each sample wood strip under absolute dryness by adopting a drying method 0 The method comprises the steps of carrying out a first treatment on the surface of the Drying the wood strips in an oven at 103 ℃ to remove water, and continuously monitoring the weight change; when the weight change is smaller than the preset weight difference in the preset time period, the sample wood strip is considered to be in an absolute dry state, and the weight of the wood strip at the moment is the absolute dry weight of the sample wood stripMeasuring amountm 0 The method comprises the steps of carrying out a first treatment on the surface of the The weight and absolute weight of each sample stick were taken into the formula: mc= (m w - m 0 )/ m 0 Calculating the real water content MC of the corresponding sample wood strip;
step four: inputting the water content MC of the sample wood strip obtained in the third step into a computer to fit a relation curve corresponding to the capacitance value Cs measured in the second step, and obtaining an MC-Cs graduation table of the wood;
step five: the ratio of the two calibration particles is regulated to form a preset mixed calibration particle with low dielectric constant, and the mixed calibration particle is filled in a measuring area of the sampling capacitance sensor to measure the capacitance Cs l Then, looking up the index table in the fourth step to obtain the corresponding moisture MC l Meanwhile, the mixed particles are used for calibrating the empty tube of ECT to obtain the empty tube capacitor with the corresponding ECT image gray level of 0; the ratio of the two particles is regulated to form a preset mixed calibration particle h with high dielectric constant, and the mixed calibration particle h is filled in a sampling capacitance sensor to measure the capacitance Cs of the sampling capacitance sensor h Then, checking the graduation table of the wood MC-Cs in the fourth step to obtain the corresponding moisture MC h Meanwhile, the mixed particles are used for full tube calibration of ECT, and the full tube capacitance with the corresponding ECT image gray level of 1 is obtained;
step six: reconstructing a gray image according to the ECT calibrated in the fifth step, and converting the gray of the image into a water content graduation table according to the gray and water content relation in the fifth step.
8. The method for calibrating the moisture capacitance tomography of the medium substitution wood structure according to claim 7, wherein the method is characterized by comprising the following steps of: the sixth step is specifically as follows: replacing the coordinate axis representing the capacitance value in the MC-Cs graduation table of the wood with a gray coordinate axis, wherein the coordinate axis representing the moisture is unchanged; based on the empty-full tube calibration result in the fifth step, two points with corresponding gray scales of 0 and 1 in the relation curve are found; dividing equally between the two points with the gray level of 0 and 1, and converting the MC-Cs graduation table of the wood into an MC-g graduation table.
9. The method for calibrating the moisture capacitance tomography of the medium substitution wood structure according to claim 7, wherein the method is characterized by comprising the following steps of: in the first step, the water content distribution range of 5 similar sample wood strips with different water contents is 15% -50%, and the difference of the water contents is more than 5%.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN118362614A (en) * | 2024-06-20 | 2024-07-19 | 湖南大学 | Automatic calibration method, device, equipment and medium for capacitance tomography |
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| CN118362614A (en) * | 2024-06-20 | 2024-07-19 | 湖南大学 | Automatic calibration method, device, equipment and medium for capacitance tomography |
| CN118362614B (en) * | 2024-06-20 | 2024-09-10 | 湖南大学 | Automatic calibration method, device, equipment and medium for capacitance tomography |
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