Probe deflection correction method and device for trunk liquid flow thermal pulse probe

Abstract

The invention provides a probe deflection correction method and device for a trunk liquid flow heat pulse probe. The method comprises the following steps: determining xylem volume heat capacity through tree water content and dry material density obtained through real-time measurement; under the condition that it is judged that the liquid flow speed is within the preset speed interval, in the time range from the heat pulse closing moment to the first preset moment, nonlinear fitting is conducted on the change rule of the temperature difference of the upstream probe along with time and the change rule of the temperature difference of the downstream probe along with time, and the heat conductivity is obtained; dividing the thermal conductivity by the xylem volume thermal capacity to obtain a thermal diffusion coefficient; on the basis of a heat convection conduction equation, calculating according to the heat conductivity and the heat diffusion coefficient to obtain an upstream probe actual distance and a downstream probe actual distance; compared with an interval correction method based on a single probe benchmark in the prior art which is unstable in different deflection scenes, solution of the actual interval of the probes is not affected by the deflection scenes, stability of correction is guaranteed, and accuracy is high.

Description

Technical Field

[0001] The present invention relates to the field of tree trunk sap flow measurement, and in particular to a probe deflection correction method and device for a tree trunk sap flow thermal pulse probe. Background Art

[0002] Measuring trunk sap flow is a key technology for studying plant water transport, transpiration, and water use efficiency. Trunk sap flow is the rate of water transport within a tree trunk. Currently, the main methods for measuring trunk sap flow include the heat pulse method. This method generates a heat pulse in the xylem by heating a probe, and the speed of the heat signal propagating through the sap flow is measured to infer the sap flow rate. Heat pulse probes are sensors that measure trunk sap flow by heating and monitoring temperature changes. They typically consist of a heating electrode and a temperature measuring electrode.

[0003] Probe deflection in a heat pulse probe for tree trunk sap flow occurs when the probe's actual position or angle deviates from the preset orientation after insertion into the trunk due to mechanical stress, wood shrinkage and expansion, or improper installation. A commonly used method to address probe deflection is a spacing correction method based on a single-probe datum. Specifically, this method assumes the accurate position of one probe, calculates the offset of the other probe, and then takes the average. This assumption does not conform to the actual probe deflection. Numerical simulation results also yield similar conclusions: when both the upstream and downstream probes deflect by 1 mm, the spacing correction method based on a single-probe datum reduces the Vh error from -13% to 7.5%. When the downstream probe deflects outward by 1 mm, the method reduces the error from -14.3% to -7.1%. However, when the upstream probe deflects inward by 1 mm, the Vh error increases from 1.3% to 10.3%. These results indicate that this method is unstable under different deflection scenarios. The Vh error (heat pulse velocity error) is the difference between the sap velocity calculated using the heat pulse method and the actual sap velocity. Summary of the Invention

[0004] The present invention provides a probe deflection correction method and device for a trunk sap flow thermal pulse probe, which is used to solve the defect that the spacing correction method based on a single probe benchmark in the prior art is unstable under different deflection scenarios, and to achieve stability and high accuracy of probe spacing correction.

[0005] The present invention provides a probe deflection correction method for a trunk sap flow thermal pulse probe, comprising the following steps: Determine the xylem volumetric heat capacity by measuring the tree water content and dry wood density in real time; When the liquid flow velocity is determined to be within a preset velocity range, a nonlinear fitting is performed on a temporal variation pattern of the upstream probe temperature difference and a temporal variation pattern of the downstream probe temperature difference within a time range from the time when the heat pulse is turned off to the first preset time to obtain the thermal conductivity; The thermal diffusivity is obtained by dividing the thermal conductivity and the volumetric heat capacity of the xylem; The actual spacing between upstream and downstream probes is calculated based on the heat convection conduction equation according to the thermal conductivity and thermal diffusivity.

[0006] A probe deflection correction method for a trunk sap flow thermal pulse probe according to the present invention further includes: Measuring the current probe distance and current probe temperature at multiple specified measurement moments within a preset time period; wherein the current probe distance includes: the distance between the upstream probe and the heating probe at the specified measurement moment, and the distance between the downstream probe and the heating probe at the specified measurement moment; the current probe temperature includes: the temperature of the upstream probe at the specified measurement moment, and the temperature of the downstream probe at the specified measurement moment; Calculating the adjacent time temperature difference between the specified measurement time and the last adjacent measurement time based on the multiple current probe temperatures; wherein the adjacent time temperature difference includes: the temperature difference of the upstream probe and the temperature difference of the downstream probe; The liquid flow velocity at the designated measurement time is calculated based on the time from the start of the heat pulse to the designated measurement time, the duration of the heat pulse, the current probe distance, and the temperature difference between adjacent times; When it is determined that the liquid flow velocity at multiple specified measurement moments changes linearly with increasing time, the result of the probe deflection is returned.

[0007] According to a probe deflection correction method for a trunk sap flow thermal pulse probe provided by the present invention, the sap flow velocity at a specified measurement time is calculated based on the time from the start of the thermal pulse to the specified measurement time, the thermal pulse duration, the current probe distance, and the temperature difference between adjacent times, and is implemented by the following formula: in, ; is the thermal pulse velocity; D is the thermal diffusivity; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the temperature difference of the downstream probe; is the temperature difference of the upstream probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

[0008] According to a probe deflection correction method for a trunk sap flow thermal pulse probe provided by the present invention, the volumetric heat capacity of the wood is determined by real-time measurement of the water content and dry wood density of the tree, which is achieved by the following formula: in, is the volumetric heat capacity of the xylem; is the dry wood density; is the heat capacity of water; is the heat capacity of dry wood; The water content of the tree.

[0009] According to a probe deflection correction method for a trunk sap flow thermal pulse probe provided by the present invention, the temporal variation of the upstream probe temperature difference and the temporal variation of the downstream probe temperature difference are realized by the following formula: in, is the temperature difference, is thermal conductivity; is the volumetric heat capacity of the xylem; q is the energy input per unit length and per unit time of the heater; x is the distance between the upstream probe or downstream probe and the heating probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

[0010] According to a probe deflection correction method for a trunk sap flow thermal pulse probe provided by the present invention, the actual upstream probe spacing and the actual downstream probe spacing are calculated based on the heat convection conduction equation according to the thermal conductivity and thermal diffusivity, and are implemented by the following formula: in, is the temperature difference of the downstream probe; is the upstream probe temperature difference; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the thermal pulse velocity; D is the thermal diffusivity.

[0011] The present invention also provides a probe deflection correction device for a trunk sap flow thermal pulse probe, comprising the following modules: A xylem volume heat capacity determination module is used to determine the xylem volume heat capacity based on the tree water content and dry wood density measured in real time; a thermal conductivity calculation module for determining that the liquid flow velocity is within a preset velocity range, and performing nonlinear fitting on the temporal variation of the upstream probe temperature difference and the temporal variation of the downstream probe temperature difference within a time range from the time when the heat pulse is turned off to the first preset time, to obtain the thermal conductivity; Thermal diffusivity calculation module, used to obtain thermal diffusivity by dividing thermal conductivity and xylem volume heat capacity; The actual spacing calculation module is used to calculate the actual spacing between upstream probes and the actual spacing between downstream probes based on the heat convection conduction equation according to the thermal conductivity and the thermal diffusivity.

[0012] According to the present invention, a probe deflection correction device for a trunk sap flow thermal pulse probe further comprises: A probe deflection determination module is used to measure the current probe distance and current probe temperature at multiple specified measurement moments within a preset time period; wherein, the current probe distance includes: the distance between the upstream probe and the heating probe at the specified measurement moment and the distance between the downstream probe and the heating probe at the specified measurement moment; the current probe temperature includes: the temperature of the upstream probe at the specified measurement moment and the temperature of the downstream probe at the specified measurement moment; the adjacent moment temperature difference between the specified measurement moment and the previous adjacent measurement moment is calculated based on multiple current probe temperatures; wherein, the adjacent moment temperature difference includes: the temperature difference of the upstream probe and the temperature difference of the downstream probe; the liquid flow velocity at the specified measurement moment is calculated based on the time from the start moment of the heat pulse to the specified measurement moment, the duration of the heat pulse, the current probe distance and the adjacent moment temperature difference; when it is judged that the liquid flow velocity at multiple specified measurement moments changes linearly with increasing time, the result of probe deflection is returned.

[0013] According to a probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention, the probe deflection determination module calculates the sap flow velocity at the specified measurement time based on the time from the start of the thermal pulse to the specified measurement time, the thermal pulse duration, the current probe distance, and the temperature difference between adjacent times, and is implemented by the following formula: in, ; is the thermal pulse velocity; D is the thermal diffusivity; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the temperature difference of the downstream probe; is the temperature difference of the upstream probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

[0014] According to a probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention, the xylem volumetric heat capacity determination module determines the xylem volumetric heat capacity by using the tree water content and dry wood density obtained by real-time measurement, which is achieved by the following formula: in, is the volumetric heat capacity of the xylem; is the dry wood density; is the heat capacity of water; is the heat capacity of dry wood; The water content of the tree.

[0015] According to a probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention, the temporal variation of the upstream probe temperature difference and the temporal variation of the downstream probe temperature difference in the thermal conductivity calculation module are realized by the following formula: in, is the temperature difference, is thermal conductivity; is the volumetric heat capacity of the xylem; q is the energy input per unit length and per unit time of the heater; x is the distance between the upstream probe or downstream probe and the heating probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

[0016] According to a probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention, the actual spacing calculation module calculates the actual spacing between upstream and downstream probes based on the thermal conductivity and thermal diffusivity equation using the following formula: in, is the temperature difference of the downstream probe; is the upstream probe temperature difference; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the thermal pulse velocity; D is the thermal diffusivity.

[0017] The present invention also provides an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for correcting probe deflection of a trunk sap flow thermal pulse probe as described above is implemented.

[0018] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for correcting probe deflection of a trunk sap flow thermal pulse probe as described above is implemented.

[0019] The present invention also provides a computer program product, comprising a computer program, which, when executed by a processor, implements the probe deflection correction method for the trunk sap flow thermal pulse probe as described above.

[0020] The present invention provides a probe deflection correction method and device for a trunk sap flow thermal pulse probe. The method determines the xylem volumetric heat capacity using real-time measurements of tree water content and dry wood density. When the sap flow velocity is determined to be within a preset velocity range, the temporal variation of the upstream probe temperature difference and the temporal variation of the downstream probe temperature difference are nonlinearly fitted within the time range from the thermal pulse off time to a first preset time to obtain thermal conductivity. The thermal conductivity is divided by the xylem volumetric heat capacity to obtain the thermal diffusivity. The actual upstream and downstream probe spacings are calculated based on the thermal conductivity and thermal diffusivity using the heat convection conduction equation. Compared to existing single-probe reference spacing correction methods that exhibit instability under different deflection scenarios, the present invention solves for the thermal diffusivity in real time based on tree water content changes and temperature measurement data, thereby determining the actual probe spacing. The actual probe spacing is unaffected by deflection scenarios, ensuring calibration stability and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a flow chart of the probe deflection correction method of the trunk sap flow thermal pulse probe provided by the present invention.

[0023] Figure 2 It is a structural schematic diagram of the probe deflection correction device of the trunk sap flow thermal pulse probe provided by the present invention.

[0024] Figure 3 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0026] The following combination Figure 1-Figure 3 The present invention is described.

[0027] Figure 1Schematic diagram of the flow of the probe deflection correction method of the trunk sap flow thermal pulse probe provided by the present invention, as shown in FIG. Figure 1 As shown, the method includes the following: Optionally, before step 101, the present invention provides a method for correcting probe deflection of a trunk sap flow thermal pulse probe, further comprising steps A1 to A4: Step A1: Measure the current probe distance and the current probe temperature at multiple specified measurement moments within a preset time period; wherein, the current probe distance includes: the distance between the upstream probe and the heating probe at the specified measurement moment and the distance between the downstream probe and the heating probe at the specified measurement moment; the current probe temperature includes: the temperature of the upstream probe at the specified measurement moment and the temperature of the downstream probe at the specified measurement moment.

[0028] Step A2: Calculate the adjacent time temperature difference between the designated measurement time and the last adjacent measurement time based on the multiple current probe temperatures; wherein the adjacent time temperature difference includes: the temperature difference of the upstream probe and the temperature difference of the downstream probe.

[0029] Step A3: Calculate the liquid flow velocity at the designated measurement time based on the time from the start of the heat pulse to the designated measurement time, the heat pulse duration, the current probe distance, and the temperature difference between adjacent times.

[0030] Step A4: When it is determined that the liquid flow velocity at a plurality of designated measurement moments changes linearly with increasing time, a result indicating that the probe has deflected is returned.

[0031] Optionally, in step A3 above, the liquid flow velocity at the designated measurement time is calculated based on the time from the start of the heat pulse to the designated measurement time, the duration of the heat pulse, the current probe distance, and the temperature difference between adjacent times, using the following formula: in, ; is the thermal pulse velocity; D is the thermal diffusivity; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the temperature difference of the downstream probe; is the temperature difference of the upstream probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

[0032] In steps A1 through A4 above, probe deflection during long-term measurements due to trunk growth or mechanical stress can lead to calculation errors. The linear change in the heat pulse velocity is monitored to determine whether the probe spacing deviates from the initial value. Temperature data is collected using a CR1000 or CR1000X data logger.

[0033] To ensure data accuracy, the probe needs to be accurately measured when it is initially installed. and .generally and Use a vernier caliper for calibration. After installation, install a heat insulation layer to reduce the impact of the external environment.

[0034] If the formula (1) is used to obtain When the fluctuation shows a linear increase or linear decrease during 60 to 100 s, it indicates that the probe spacing has deviated.

[0035] When the fluctuation shows linear growth or linear decrease during 60 to 100 seconds, it means that the probe has deflected. When the probe does not deflect, even if it is disturbed by the external temperature, Fluctuations should be random, with no specific pattern. Probe spacing calibration is only necessary after it is determined that the probe has deflected. Therefore, determining probe deflection in advance can reduce workload.

[0036] Step 101: Determine the volumetric heat capacity of the wood using the tree water content and dry wood density measured in real time.

[0037] In the above step 101, the water content of the tree can be measured by time domain reflectometry (TDR) or frequency domain reflectometry (FDR). θ .

[0038] Optionally, in step 101, the wood volume heat capacity is determined by measuring the tree water content and dry wood density in real time, and this is achieved by the following formula: in, is the volumetric heat capacity of the xylem; is the dry wood density; is the heat capacity of water; is the heat capacity of dry wood; The water content of the tree.

[0039] Dry wood density can be measured by coring.

[0040] The thermal properties of wood change with moisture content and need to be corrected in real time. ρcThis provides a basis for the subsequent solution of D and K. When measuring tree moisture content using TDR / FDR, ensure close contact between the probe and the wood, avoiding air gaps. After measuring dry wood density using the coring method, the sample must be sealed immediately to prevent moisture loss.

[0041] Step 102: When it is determined that the liquid flow velocity is within the preset velocity range, a nonlinear fitting is performed on the temporal variation pattern of the upstream probe temperature difference and the temporal variation pattern of the downstream probe temperature difference within the time range from the heat pulse off moment to the first preset moment to obtain the thermal conductivity.

[0042] In the above step 102, the preset speed interval is a range interval close to 0, which can be set according to actual needs.

[0043] Optionally, the temporal variation of the upstream probe temperature difference and the temporal variation of the downstream probe temperature difference in step 102 are implemented by the following formula: (2) in, is the temperature difference, is thermal conductivity; is the volumetric heat capacity of the xylem; q is the energy input per unit length and per unit time of the heater; x is the distance between the upstream probe or downstream probe and the heating probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

[0044] When the flow rate is close to 0 at night, according to formula (2), using Δ T d ~ t or Δ T u ~ t Perform nonlinear fitting to determine the thermal conductivity ( K ).

[0045] Numerous studies have shown that tree transpiration is weak at night, with sap flow velocity approaching zero. At this time, the heat pulse signal reflects only the thermal conductivity of the wood itself, allowing for independent calculation of K. It should be noted that the determination of thermal conductivity K is unaffected by probe spacing deflection.

[0046] To ensure data accuracy, the stability of q needs to be maintained. The circuit is connected to a regulated power supply to control the fluctuation of q and reduce errors.

[0047] Step 103: Divide the thermal conductivity and the wood volume heat capacity to obtain the thermal diffusion coefficient.

[0048] Step 104 : Calculate the actual distance between upstream probes and the actual distance between downstream probes based on the heat convection conduction equation according to the thermal conductivity and the thermal diffusivity.

[0049] Optionally, the actual spacing between upstream and downstream probes is calculated based on the thermal conductivity and thermal diffusivity equation in step 104, which is implemented by the following formula: (3) in, is the temperature difference of the downstream probe; is the upstream probe temperature difference; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the thermal pulse velocity; D is the thermal diffusivity.

[0050] In step 104 above, the probe deflection causes and If the value deviates from the actual value, dynamic correction is required. The actual probe spacing is obtained by inverting the equation of formula (3).

[0051] The present invention does not assume that D Constant. By solving the thermal conductivity when the flow rate is 0, the heat capacity can be obtained. ρc , we can find D The principle of the embodiment of the present invention is that the probe deflection K The solution of does not affect, so even if the specific deflection of the probe is not known, K The advantage of the embodiment of the present invention is that it can be adjusted in real time according to the changes in the water content of the tree. D Instead of assuming it remains constant throughout the year, the D The error in the flow rate solution caused by the constant.

[0052] In addition, the thermal characteristics of the tree were determined at zero velocity ( K and D ), which simplifies the equation for solving the probe spacing. Specifically, this method can determine the upstream and downstream probe spacing based on the two formulas in the above formula (3).

[0053] The embodiment of the present invention can be applied to any tree species and trunks of any diameter. The embodiment of the present invention performs an indirect solution based on temperature measurement data rather than performing on-site measurement with a probe, and is not affected by the size of the trunk.

[0054] The principle of the application of the present invention to long-term testing is that the probe spacing is determined based on real-time data, including real-time trunk moisture content and real-time temperature data. Even if the probes deflect as the trunk grows, the probe spacing can be corrected at any time.

[0055] The present invention provides a probe deflection correction method for a tree trunk sap flow thermal pulse probe. The method determines the xylem volumetric heat capacity using real-time measurements of tree water content and dry wood density. When the sap flow velocity is determined to be within a preset velocity range, the temporal variation of the upstream probe temperature difference and the temporal variation of the downstream probe temperature difference are nonlinearly fitted within the time range from the thermal pulse off time to a first preset time to obtain thermal conductivity. The thermal conductivity is divided by the xylem volumetric heat capacity to obtain the thermal diffusivity. The actual upstream and downstream probe spacings are calculated based on the thermal conductivity and thermal diffusivity based on the heat convection conduction equation. Compared to existing single-probe reference spacing correction methods that exhibit instability under different deflection scenarios, this method can solve for the thermal diffusivity in real time based on tree water content changes and temperature measurement data, thereby determining the actual probe spacing. The solution to the actual probe spacing is unaffected by deflection scenarios, ensuring calibration stability and high accuracy.

[0056] The probe deflection correction device of the trunk sap flow thermal pulse probe provided by the present invention is described below. The probe deflection correction device of the trunk sap flow thermal pulse probe described below and the probe deflection correction method of the trunk sap flow thermal pulse probe described above can be referenced to each other.

[0057] Figure 2 This is a schematic diagram of the flow chart of the probe deflection correction device for the trunk sap flow thermal pulse probe provided by the present invention. Figure 2 As shown, the device includes the following: The xylem volume heat capacity determination module 201 is used to determine the xylem volume heat capacity based on the tree water content and dry wood density measured in real time.

[0058] The thermal conductivity calculation module 202 is used to determine that the liquid flow velocity is within a preset velocity range, and to obtain the thermal conductivity by performing nonlinear fitting on the temporal variation pattern of the upstream probe temperature difference and the temporal variation pattern of the downstream probe temperature difference within the time range from the thermal pulse off time to the first preset time.

[0059] The thermal diffusion coefficient calculation module 203 is used to obtain the thermal diffusion coefficient by dividing the thermal conductivity and the volume heat capacity of the wood.

[0060] The actual spacing calculation module 204 is configured to calculate the actual spacing between upstream probes and the actual spacing between downstream probes based on the heat convection conduction equation according to the thermal conductivity and the thermal diffusion coefficient.

[0061] Optionally, the probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention further includes: A probe deflection determination module is used to measure the current probe distance and current probe temperature at multiple specified measurement moments within a preset time period; wherein, the current probe distance includes: the distance between the upstream probe and the heating probe at the specified measurement moment and the distance between the downstream probe and the heating probe at the specified measurement moment; the current probe temperature includes: the temperature of the upstream probe at the specified measurement moment and the temperature of the downstream probe at the specified measurement moment; the adjacent moment temperature difference between the specified measurement moment and the previous adjacent measurement moment is calculated based on multiple current probe temperatures; wherein, the adjacent moment temperature difference includes: the temperature difference of the upstream probe and the temperature difference of the downstream probe; the liquid flow velocity at the specified measurement moment is calculated based on the time from the start moment of the heat pulse to the specified measurement moment, the duration of the heat pulse, the current probe distance and the adjacent moment temperature difference; when it is judged that the liquid flow velocity at multiple specified measurement moments changes linearly with increasing time, the result of probe deflection is returned.

[0062] Optionally, in a probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention, the probe deflection determination module calculates the sap flow velocity at a specified measurement time based on the time from the start of the thermal pulse to the specified measurement time, the thermal pulse duration, the current probe distance, and the temperature difference between adjacent times, and is implemented by the following formula: in, ; is the thermal pulse velocity; D is the thermal diffusivity; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the temperature difference of the downstream probe; is the temperature difference of the upstream probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

[0063] Optionally, in the probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention, the xylem volumetric heat capacity determination module 201 determines the xylem volumetric heat capacity using the tree water content and dry wood density measured in real time, and this is achieved using the following formula: in, is the volumetric heat capacity of the xylem; is the dry wood density; is the heat capacity of water; is the heat capacity of dry wood; The water content of the tree.

[0064] Optionally, in the probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention, the temporal variation pattern of the upstream probe temperature difference and the temporal variation pattern of the downstream probe temperature difference in the thermal conductivity calculation module 202 are implemented by the following formula: in, is the temperature difference, is thermal conductivity; is the volumetric heat capacity of the xylem; q is the energy input per unit length and per unit time of the heater; x is the distance between the upstream probe or downstream probe and the heating probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

[0065] Optionally, in the probe deflection correction device for a trunk sap flow thermal pulse probe provided by the present invention, the actual spacing calculation module 204 calculates the actual spacing of the upstream probe and the actual spacing of the downstream probe based on the thermal conductivity and thermal diffusivity equation, which is implemented by the following formula: in, is the temperature difference of the downstream probe; is the upstream probe temperature difference; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the thermal pulse velocity; D is the thermal diffusivity.

[0066] The present invention provides a probe deflection correction device for a tree trunk sap flow thermal pulse probe. The device determines the xylem volumetric heat capacity using real-time measurements of tree water content and dry wood density. When the sap flow velocity is determined to be within a preset velocity range, the temporal variation of the upstream probe temperature difference and the temporal variation of the downstream probe temperature difference are nonlinearly fitted within the time range from the thermal pulse off time to a first preset time to obtain thermal conductivity. The thermal conductivity is divided by the xylem volumetric heat capacity to obtain the thermal diffusivity. The actual spacing between the upstream and downstream probes is calculated based on the thermal conductivity and thermal diffusivity using the heat convection conduction equation. Compared to existing spacing correction methods based on a single probe reference, which exhibit instability under different deflection scenarios, the device can solve for the thermal diffusivity in real time based on tree water content changes and temperature measurement data, thereby determining the actual probe spacing. The actual probe spacing is not affected by deflection scenarios, ensuring calibration stability and high accuracy.

[0067] Figure 3 An example of a physical structure diagram of an electronic device is shown below. Figure 3 As shown, the electronic device may include a processor 810, a communications interface 820, a memory 830, and a communications bus 840. The processor 810, the communications interface 820, and the memory 830 communicate with each other via the communications bus 840. The processor 810 may invoke logic instructions in the memory 830 to execute a probe deflection correction method for a trunk sap flow thermal pulse probe.

[0068] Furthermore, the logic instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product, stored in a storage medium, includes instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0069] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the probe deflection correction method of the trunk sap flow thermal pulse probe provided by the above methods.

[0070] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is used to implement the probe deflection correction method of the trunk sap flow thermal pulse probe provided by the above methods when the computer program is executed by a processor.

[0071] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0072] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for correcting probe deflection of a trunk sap flow thermal pulse probe, characterized in that: include: Determine the xylem volumetric heat capacity by measuring the tree water content and dry wood density in real time; When the liquid flow velocity is determined to be within a preset velocity range, a nonlinear fitting is performed on a temporal variation pattern of the upstream probe temperature difference and a temporal variation pattern of the downstream probe temperature difference within a time range from the time when the heat pulse is turned off to the first preset time to obtain the thermal conductivity; Dividing the thermal conductivity by the volumetric heat capacity of the wood to obtain a thermal diffusivity; The actual distance between upstream probes and the actual distance between downstream probes are calculated based on the heat convection conduction equation according to the thermal conductivity and the thermal diffusivity.

2. The probe deflection correction method of the trunk sap flow thermal pulse probe according to claim 1, characterized in that: The method further comprises: Measuring the current probe distance and current probe temperature at multiple specified measurement moments within a preset time period; wherein the current probe distance includes: the distance between the upstream probe and the heating probe at the specified measurement moment and the distance between the downstream probe and the heating probe at the specified measurement moment; the current probe temperature includes: the temperature of the upstream probe at the specified measurement moment and the temperature of the downstream probe at the specified measurement moment; Calculating the adjacent time temperature difference between the specified measurement time and the previous adjacent measurement time based on the multiple current probe temperatures; wherein the adjacent time temperature difference includes: the temperature difference of the upstream probe and the temperature difference of the downstream probe; Calculating the liquid flow velocity at the designated measurement time based on the time from the start of the heat pulse to the designated measurement time, the heat pulse duration, the current probe distance, and the temperature difference between adjacent times; When it is determined that the liquid flow velocity at multiple specified measurement moments changes linearly with increasing time, the result of the probe deflection is returned.

3. The probe deflection correction method of the trunk sap flow thermal pulse probe according to claim 2, characterized in that: The liquid flow velocity at the designated measurement time is calculated based on the time from the start of the heat pulse to the designated measurement time, the heat pulse duration, the current probe distance, and the temperature difference at adjacent times, and is achieved by the following formula: in, ; is the thermal pulse velocity; D is the thermal diffusivity; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the temperature difference of the downstream probe; is the temperature difference of the upstream probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

4. The probe deflection correction method of a trunk sap flow thermal pulse probe according to claim 1, characterized in that: The wood volume heat capacity is determined by measuring the tree water content and dry wood density in real time, and is achieved by the following formula: in, is the volumetric heat capacity of the xylem; is the dry wood density; is the heat capacity of water; is the heat capacity of dry wood; The water content of the tree.

5. The probe deflection correction method of a trunk sap flow thermal pulse probe according to claim 1, characterized in that: The change of upstream probe temperature difference over time and the change of downstream probe temperature difference over time are realized by the following formula: in, is the temperature difference, is thermal conductivity; is the volumetric heat capacity of the xylem; q is the energy input per unit length and per unit time of the heater; x is the distance between the upstream probe or downstream probe and the heating probe; is the duration of the heat pulse; It is the time from the start of the heat pulse to the specified measurement time.

6. The probe deflection correction method of a trunk sap flow thermal pulse probe according to claim 5, characterized in that: The actual distance between upstream and downstream probes is calculated based on the thermal conductivity and the thermal diffusivity according to the heat convection conduction equation, which is achieved by the following formula: in, is the temperature difference of the downstream probe; is the upstream probe temperature difference; is the distance between the downstream probe and the heating probe; is the distance between the upstream probe and the heating probe; is the thermal pulse velocity; D is the thermal diffusivity.

7. A probe deflection correction device for a tree trunk sap flow thermal pulse probe, characterized in that: include: A xylem volume heat capacity determination module is used to determine the xylem volume heat capacity based on the tree water content and dry wood density measured in real time; a thermal conductivity calculation module for determining that the liquid flow velocity is within a preset velocity range, and performing nonlinear fitting on the temporal variation of the upstream probe temperature difference and the temporal variation of the downstream probe temperature difference within a time range from the time when the heat pulse is turned off to the first preset time, to obtain the thermal conductivity; a thermal diffusion coefficient calculation module, configured to obtain a thermal diffusion coefficient by dividing the thermal conductivity by the volumetric heat capacity of the wood; The actual spacing calculation module is used to calculate the actual spacing between upstream probes and the actual spacing between downstream probes based on the thermal convection conduction equation according to the thermal conductivity and the thermal diffusion coefficient.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the probe deflection correction method for the trunk sap flow thermal pulse probe according to any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the probe deflection correction method of the trunk sap flow thermal pulse probe according to any one of claims 1 to 6 is implemented.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the probe deflection correction method of the trunk sap flow thermal pulse probe according to any one of claims 1 to 6 is implemented.

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