A method and device for directionally measuring regional soil moisture

Abstract

The present invention relates to a method and device for directionally measuring regional soil moisture. By arranging two or more scintillators at intervals in the same direction, neutrons fly from one direction and pass through each scintillator in turn. The scintillators flash in a certain order, and the flash order of the scintillators is detected by the light-emitting induction unit, so that the source direction of the neutrons can be judged. By counting the neutrons in the set source direction, the soil water content in the corresponding direction can be detected. The device of the present invention has a simple structure and low cost, can be arranged at the edge of the land to be measured while accurately measuring the water content of the corresponding land, and does not affect the production operations on the land.

Description

Technical Field

[0001] The present invention relates to a method and device for directionally measuring regional soil moisture, belonging to the technical field of soil moisture measurement; in particular, it relates to a method and device capable of measuring the soil moisture content in a set direction in a region. Background Art

[0002] In industries such as ecology, meteorology, hydrology, and agriculture, the measurement of soil moisture is of great significance. Currently, widely used methods include time domain reflectometry, frequency domain reflectometry, capacitance method, standing wave method, etc. These measurement techniques are all based on dielectric theory, directly or indirectly measuring the dielectric properties of the soil, and then calibrating the soil moisture using the regression method according to the relationship between soil moisture and dielectric properties. The measurement range of such methods is limited to dozens of centimeters around the sensor. Generally, limited points are selected to represent the surrounding area, and the accurate regional soil moisture cannot be truly measured.

[0003] The soil moisture automatic monitor based on cosmic ray soil moisture automatic measurement technology is a soil moisture automatic measurement device with a relatively large measurement area (hundreds of mu). Its basic principle is: cosmic ray particles collide with atomic nuclei to generate high-energy neutrons. When these high-energy neutrons pass through air and soil, they undergo elastic collisions with atomic nuclei in the medium, especially hydrogen atoms (protons) with a mass equivalent to their own, and change direction, losing some energy and gradually slowing down to fast neutrons; the fast neutrons continue to undergo elastic collisions with hydrogen atoms (protons), and continue to slow down to slow neutrons until they are converted into heat energy. However, not all fast neutrons can be slowed down to slow neutrons, and some fast neutrons escape to the ground surface and quickly reach equilibrium. Since the number of neutrons is significantly affected by the humidity of the surface soil, the fast neutron cloud in the near-surface environment is inversely proportional to the soil moisture. The higher the soil moisture, the thinner the fast neutron cloud, and the lower the soil moisture, the denser the fast neutron cloud. Therefore, by detecting the number of fast neutrons near the ground surface, the average soil moisture content of a large area can be calculated.

[0004] With its advantages of large measurement range, being unaffected by soil texture, physical and chemical factors, and soil water phase state, and non-contact in-situ measurement, this device has become the most promising measurement technology for near-surface regional soil moisture measurement. However, since the horizontal measurement area contour is circular, the detection device needs to be installed near the center of the soil area to be measured in order to obtain a relatively accurate soil moisture observation value for this area. When installed at the center position of the area, the device will affect agricultural activities, manual operations, etc. And as Figure 1 shown, when the device is set at the edge of the soil block to be measured, or because the shape of the soil block to be measured is irregular, resulting in the circular measurement area of the device including other plots that do not need to be detected, it will cause a large deviation between the measurement result and the actual situation, affecting the measurement accuracy. Summary of the Invention

[0005] The object of the present invention is to provide a method and device for directionally measuring regional soil moisture, so as to solve the problem of measurement result deviation in the prior art that the soil moisture measurement device based on cosmic rays is arranged at the edge of the area to be measured.

[0006] To achieve the above object, the solution of the present invention includes:

[0007] A technical solution of a device for directionally measuring regional soil moisture of the present invention includes at least two scintillators arranged at intervals in the same direction, and the direction in which the scintillators are arranged is used for facing the direction of the area where the soil moisture is to be measured; a light emission sensing unit is arranged for each adjacent scintillator to detect the light emission of the corresponding scintillator; each light emission detection unit is used to connect to a processing chip.

[0008] In the present invention, by arranging more than two scintillators at intervals in the same direction (or on the same straight line), neutrons fly from one direction and pass through each scintillator in turn. The scintillators flash in a certain order, and the light emission sensing unit detects the light emission order of the scintillators, and the device of the present invention can judge the source direction of the neutrons. By counting the neutrons in the set source direction, the detection of the soil water content in the corresponding direction can be realized. The device of the present invention has a simple structure and low cost, and can be arranged at the edge of the land to be measured while accurately measuring the water content of the corresponding land, without affecting the production operations on the land.

[0009] Further, the scintillator is in the shape of a thin plate, and each thin plate-shaped scintillator is arranged in parallel at intervals.

[0010] Further, there are two scintillators, and the light emission sensing unit is arranged on the side of the corresponding scintillator that is not adjacent to the other scintillator.

[0011] Further, the light emission sensing unit is a photomultiplier tube.

[0012] By arranging the photomultiplier tube as the light emission sensing unit on the side facing outwards of the two oppositely arranged thin plate-shaped scintillators, the light emission of the two scintillators can be accurately detected without interference.

[0013] Further, it further includes a base and a housing that are hermetically fitted, and the scintillator and the light emission sensing unit are arranged on the base in the housing through a bracket.

[0014] The sealed housing can protect the device buried in the soil and extend the service life of the device.

[0015] Technical solution of a method for directionally measuring regional soil moisture according to the present invention: at least two scintillators are arranged at intervals in the direction towards the area where soil moisture is to be measured on the edge of the area where soil moisture is to be measured, and the light emission of each scintillator is detected by a light emission sensing unit; when two adjacent scintillators flash in sequence within a set time interval, if the direction of the sequential flashing order is away from the direction of the area where soil moisture is to be measured, then the number of neutrons from the area where soil moisture is to be measured is incremented by 1; the soil moisture in the corresponding area is calculated based on the number of neutrons from the area where soil moisture is to be measured.

[0016] In the present invention, by arranging two or more scintillators at intervals in the same direction (or on the same straight line), neutrons fly from one direction and pass through each scintillator in sequence. The scintillators flash in a certain order in sequence, and the light emission sensing unit detects the flashing order of the scintillators, enabling the determination of the source direction of the neutrons. By counting the neutrons in the set source direction, the detection of soil water content in the corresponding direction can be achieved. The device of the present invention has a simple structure and low cost, and can be arranged at the edge of the land to be measured while accurately measuring the water content of the corresponding land, without affecting the production operations on the land.

[0017] Further, the scintillator is in the shape of a thin plate, and the thin plate-shaped scintillators are arranged in parallel at intervals.

[0018] Further, there are two scintillators, and the light emission sensing unit is arranged on the side of the corresponding scintillator that is not adjacent to the other scintillator.

[0019] Further, the light emission sensing unit is a photomultiplier tube.

[0020] Further, the scintillator and the light emission sensing unit are arranged on a base inside the housing through a bracket, and the base and the housing are hermetically fitted with each other. Description of the Drawings

[0021] Figure 1 is a schematic diagram of the measurement range of a prior art soil moisture horizontal detection device based on cosmic rays;

[0022] Figure 2 is a schematic diagram of the measurement range of the regional soil moisture directional measurement device of the present invention;

[0023] Figure 3 is a perspective view of the structural principle of the regional soil moisture directional measurement device of the present invention;

[0024] Figure 4 is a schematic diagram of the structure of the directional sensing unit of the regional soil moisture directional measurement device of the present invention.

[0025] The figure includes: 1. The first scintillator; 2. The first holder; 3. The second holder; 4. The first photomultiplier tube; 5. The first fixed ring; 6. The base; 7. The second scintillator; 8. The third holder; 9. The fourth holder; 10. The wire groove; 11. The second photomultiplier tube; 12. The second fixed ring; 13. The counter; 14. The fixed card; 15. The external cable; 16. The PG head; 17. The upper cover. Detailed implementation manners

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. That is, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Usually, the components of the embodiments of the present application described and shown in the accompanying drawings herein can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0029] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0030] Embodiment of the regional soil moisture directional measurement device:

[0031] As Figure 3 shown in the perspective view of the device of the present invention, the regional soil moisture directional measurement device of the present invention includes a base 6 and an upper cover 17. Figure 1 The upper cover 17 is made transparent to show the structural principle of the device of the present invention in perspective. The base 6 and the upper cover 17 are hermetically buckled to form a cylindrical outer shell. All components of the sensing part are fixed on the base 6 inside the upper cover 17 and are closed by the upper cover 17.

[0032] The directional sensing unit of the present invention, i.e., the sensing part, is composed of at least two scintillators arranged at intervals in the same direction. When neutrons collide with the internal material of the scintillator, optical signals are generated. The optical signals are respectively transmitted to their own photomultiplier tubes, and after photoelectric conversion and amplification, the amplified electrical signals are transmitted to the counter through cables. Through the interpretation of the counter, neutron monitoring and counting can be achieved.

[0033] The directional sensing unit of the present invention utilizes n-p scattering, that is, neutrons are scattered twice in the scintillator. Through a series of parallel-arranged scintillators, when neutrons fly from a direction towards the surface of the scintillator, they will sequentially cause the scintillators to generate optical signals according to the order of arrangement of the scintillators in this direction. According to the order of the scintillators emitting light, the flight direction of the neutrons can be judged, and thus directional measurement can be achieved.

[0034] In this embodiment, two scintillators are taken as an example. The sensing part is specifically as Figure 4 shown, including a first scintillator 1 and a second scintillator 7 processed into thin plate shapes, as well as a first photomultiplier tube 4, a second photomultiplier tube 11, and a counter 13. The first scintillator 1 is fixed on the base 6 through a first fixing frame. The first fixing frame includes a first clamping frame 2 and a second clamping frame 3. The first clamping frame 2 and the second clamping frame 3 are in the shape of columns and are respectively fixed on the base 6 by screws through two fixing holes at their respective bottoms. Long grooves are formed on the opposite sides of the first clamping frame 2 and the second clamping frame 3 from the top to the bottom. The left and right edges of the first scintillator 1 are respectively clamped into the opposite long grooves of the first clamping frame 2 and the second clamping frame 3. The second scintillator 7 is fixed on the base 6 in the same way through a third clamping frame 8 and a fourth clamping frame 9 of the second fixing frame.

[0035] The first scintillator 1 and the second scintillator 7 are separated by a certain distance and are arranged parallel and facing each other on the surface. On the non-opposite sides of the two scintillators, a first photomultiplier tube 4 and a second photomultiplier tube 11 are respectively arranged. The first scintillator 1 and the first photomultiplier tube 4 are in a group. The first photomultiplier tube 4 is used to collect the optical signal generated by the first scintillator 1, that is, when neutrons enter the scintillator, an optical signal is generated, which is amplified by the photomultiplier tube and then captured by the counter 13 as a detection device. The counter 13 performs fast neutron counting when the conditions are met according to the counting logic. The second scintillator 7 and the second photomultiplier tube 11 are in a group. The second photomultiplier tube 11 is used to collect the optical signal generated by the second scintillator 7. The first photomultiplier tube 4 is fixed in front of the outer side of the first scintillator 1 on the chassis through a stepped first fixing ring 5. The second photomultiplier tube 11 is fixed in front of the outer side of the second scintillator 7 on the chassis through a stepped second fixing ring 12. The opposite sides of the first scintillator 1 and the second scintillator 7 are defined as the inner sides of the two scintillators facing each other.

[0036] The counter 13 is arranged on the outer side of the second scintillator 7 and is adjacent to the second photomultiplier tube 11. The first photomultiplier tube 4 and the second photomultiplier tube 11 are electrically connected to the counter 13 through cables. The cable from the first photomultiplier tube 4 to the counter 13 passes under the first scintillator 1 and the second scintillator 7 through the wire groove 10 opened on the upper surface of the base 6. The cable between the second photomultiplier tube 11 and the counter 13 can also be arranged in the corresponding wire groove.

[0037] The counter 13 is fixed by a fixing card 14, and the fixing card 14 is fixed on the chassis with screws. Finally, the counter 13 outputs a counting signal and an external cable 15 for power supply through the wire passing hole opened on the base 6, and the external cable 15 is electrically connected to other devices through a PG head 16.

[0038] All components of the sensing part are fixed on the base 6 and are protected by a sealing cover. A sealing rubber ring is arranged between the upper cover 17 and the base 6 and is fixed with a setscrew. Four threaded holes are arranged on the lower surface of the base 6 to facilitate the structural fixed connection of the device of the present invention with other acquisition devices, etc.

[0039] The directional measurement principle of the device of the present invention is as follows:

[0040] Two scintillators are arranged in parallel and opposite in the device. If a neutron passes through the first scintillator 1 and the second scintillator 7 successively, the first scintillator 1 will emit light first, and then the second scintillator 7 will emit light. Moreover, since the distance between the first scintillator 1 and the second scintillator 7 is very small and the neutron speed is extremely fast, the time for the neutron to pass through the two scintillators is extremely short, at the microsecond level. If the time difference between the two flash signals is within the preset range, it can be basically determined that it is the same neutron. Therefore, when the counter 13 detects two flash signals emitted by the first scintillator 1 and the second scintillator 7 successively within the preset time range, it can be determined that the neutron source direction is the outer side of the first scintillator 1. Based on this principle, a counting logic can be formed by designing a software algorithm to calculate the approximate neutron source direction, count the neutrons with the source direction being the set direction, and then invert the regional soil moisture in the corresponding direction through the neutron flux - soil moisture relationship model to complete the directional detection.

[0041] As Figure 2 shown, if it is necessary to measure Figure 3For the soil water content in the central soil area, the device of the present invention can be set at the edge of the soil area, and only the soil moisture on the upward side (180° range) of the device in the figure is monitored. Align the side of any scintillator facing outward in the device with the area of the soil area to be detected. For example, align the side of the first scintillator 1 facing outward with the soil area. Only the neutrons from the direction of the side of the first scintillator 1 facing outward are calculated by the counter software. Assume that the monitoring range of the device of the present invention is an area with a radius of 350 meters. The finally measured semi-circular measurement area with a radius of 350m is large enough to cover most of the soil area and does not cover other areas that do not need to be measured, which can meet the detection of the soil water content of the corresponding soil area and ensure high accuracy at the same time.

[0042] At the same time, the device of the present invention can still be used to monitor the soil moisture in all directions (360° range) at the center of the area to be measured. When in use, change the algorithm to calculate all neutrons from all source directions. Then, the soil moisture in the area is inversely calculated through the relationship model between neutron flux and soil moisture.

[0043] Those skilled in the art should understand that the scintillator is a mature detector in the prior art and can emit light after absorbing high-energy particles or rays. Scintillators can be classified into inorganic scintillators and organic scintillators according to their chemical properties. In this embodiment, the organic scintillator is used in the directional sensing unit, specifically including organic crystals such as anthracene and stilbene, liquid scintillators, plastic scintillators, and so on. The specific type of scintillator is not limited in the present invention.

[0044] Embodiment of the method for directional measurement of regional soil moisture:

[0045] For the method for directional measurement of regional soil moisture of the present invention, in order to avoid the impact on agricultural production and operations in the center of the land caused by measuring the soil water volume in the center of the soil area to be measured. At least two scintillators are arranged at intervals in the direction of the area of the soil area to be measured on the edge of the soil area to be measured, and the light emission of each scintillator is detected by a photomultiplier tube as a light-emitting induction unit.

[0046] When two adjacent scintillators flash in sequence within a set time interval, considering the distance between two adjacent scintillators and the neutron flight speed, it is considered that the same neutron passes through two adjacent scintillators successively. The direction of the neutron source is judged according to the order of the optical signals emitted by the adjacent scintillators. If the direction of the successive flash order is away from the direction of the soil area to be measured, that is, the neutron comes from the direction of the scintillator that flashes first, and the scintillator that flashes first faces the soil area to be measured, then the neutrons from the soil area to be measured need to be included in the calculation of the soil water volume. Therefore, the number of neutrons from the soil area to be measured is incremented by 1; the soil moisture in the corresponding area is calculated according to the number of neutrons from the soil area to be measured.

[0047] Specifically, the method of the present invention can set the device of the present invention in the embodiment of the regional soil moisture directional measurement device at the edge of the soil area to be measured, with the outward side of the first scintillator 1 or the second scintillator 7 facing the soil area to be measured, and perform regional soil moisture directional measurement according to the directional measurement principle in the embodiment of the regional soil moisture directional measurement device. The device of the present invention and its directional measurement principle have been introduced clearly enough in the embodiment of the regional soil moisture directional measurement device, and will not be elaborated in this embodiment.

[0048] The specific implementation manners are given above, but the present invention is not limited to the described implementation manners. The basic structure and function of the present invention lie in the above basic solution. For those skilled in the art, according to the teachings of the present invention, it does not require creative labor to adopt other modules, devices, structures, and installation manners. Changes, modifications, substitutions, and variations made to the implementation manners without departing from the principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A device for directionally measuring regional soil moisture, characterized in that, it includes at least two scintillators arranged at intervals in the same direction, and the direction in which the scintillators are arranged is used to face the direction of the area where the soil moisture is to be measured; a light-emitting induction unit is arranged for each adjacent scintillator to detect the light emission of the corresponding scintillator; each light-emitting detection unit is used to connect to a processing chip; the processing chip determines, through the light-emitting detection unit, that the direction of the sequential flashing of the two scintillators is the direction away from the area where the soil moisture is to be measured, and if they flash sequentially within a set time interval, then add 1 to the number of neutrons from the area where the soil moisture is to be measured; calculate the soil moisture of the corresponding area according to the number of neutrons from the area where the soil moisture is to be measured.

2. The device for directionally measuring regional soil moisture according to claim 1, characterized in that, the scintillator is in the shape of a thin plate, and each thin-plate scintillator is arranged in parallel at intervals.

3. The device for directionally measuring regional soil moisture according to claim 2, characterized in that, there are two scintillators, and the light-emitting induction unit is arranged on the side of the corresponding scintillator that is not adjacent to the other scintillator.

4. The device for directionally measuring regional soil moisture according to any one of claims 1 to 3, characterized in that, the light-emitting induction unit is a photomultiplier tube.

5. The device for directionally measuring regional soil moisture according to claim 4, characterized in that, it further includes a base and a housing that are hermetically fitted, and the scintillator and the light-emitting induction unit are arranged on the base inside the housing through a bracket.

6. A method for directionally measuring regional soil moisture, characterized in that, at least two scintillators are arranged at intervals in the direction from the edge of the area where the soil moisture is to be measured towards the area where the soil moisture is to be measured, and the light emission of each scintillator is detected through a light-emitting induction unit; when two adjacent scintillators flash sequentially within a set time interval, then if the direction of the sequential flashing is the direction away from the area where the soil moisture is to be measured, add 1 to the number of neutrons from the area where the soil moisture is to be measured; calculate the soil moisture of the corresponding area according to the number of neutrons from the area where the soil moisture is to be measured.

7. The method for directionally measuring regional soil moisture according to claim 6, characterized in that, the scintillator is in the shape of a thin plate, and each thin-plate scintillator is arranged in parallel at intervals.

8. The method for directionally measuring regional soil moisture according to claim 7, characterized in that, there are two scintillators, and the light-emitting induction unit is arranged on the side of the corresponding scintillator that is not adjacent to the other scintillator.

9. The method for directionally measuring regional soil moisture according to any one of claims 6 to 8, characterized in that, the light-emitting induction unit is a photomultiplier tube.

10. The method for directionally measuring regional soil moisture according to claim 9, characterized in that, the scintillator and the light-emitting induction unit are arranged on the base inside the housing through a bracket, and the base and the housing are hermetically fitted to each other.

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