Damage deformation damage prediction critical value acquisition method
By obtaining the deviatoric stress-strain curve, fitting the macroscopic damage constitutive relationship, inverting the characteristic parameters, and calculating the critical strain ratio, the problem of determining the critical value for early warning of damage in coal containing gas hydrates was solved, and accurate prediction of coal damage deformation was achieved, thus preventing gas outburst accidents.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HEILONGJIANG UNIVERSITY OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2025-12-30
- Publication Date
- 2026-05-05
AI Technical Summary
The lack of existing technologies for determining the critical value for damage warning of coal bodies containing gas hydrates leads to frequent occurrences of dynamic disasters such as coal and gas outbursts.
By obtaining the deviatoric stress-strain curve, fitting the macroscopic damage constitutive relationship, inverting the characteristic parameters, determining the damage variable formula, and obtaining the critical strain and critical damage through the second derivative, the critical strain ratio is calculated to achieve damage early warning for coal bodies containing gas hydrates.
It provides accurate damage warning thresholds, enabling early prediction of coal body damage and deformation, and preventing accidents such as gas outbursts.
Smart Images
Figure CN121980992A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gas hydrate-containing coal technology, and in particular to a method for obtaining critical values for predicting damage, deformation and failure. Background Technology
[0002] As coal seam excavation depth increases, dynamic disasters such as coal and gas outbursts become more frequent. Previous studies have shown that gas hydration and solidification technology can effectively prevent such accidents. Therefore, it is crucial to conduct research on the mechanical properties of coal containing gas hydrates.
[0003] In related technologies, there is a lack of a method for determining the critical value for damage warning of coal bodies containing gas hydrates. Summary of the Invention
[0004] This invention provides a method for obtaining critical values for damage, deformation and failure prediction, which can provide a method for determining critical values for damage early warning of gas hydrate-containing coal bodies.
[0005] In a first aspect, embodiments of the present invention provide a method for obtaining critical values for damage deformation and failure prediction, comprising: S1, obtain the deviatoric stress-strain curve; S2, based on the macroscopic damage constitutive relation, the pre-peak nonlinear stage of the deviatoric stress-strain curve is fitted, and the characteristic parameters in the macroscopic damage constitutive relation are obtained by inversion: shape factor and scale parameter; S3, determine the damage variable formula based on the shape factor and the scale parameter; S4. Calculate the second derivative of the damage variable formula and take the zero value to obtain the critical strain and critical damage. S5. Determine the critical strain ratio based on the critical strain and peak strain, thus obtaining the critical value for characteristic damage warning.
[0006] Optionally, in S1, the deviatoric stress-strain curve is obtained by fitting experimental data from a triaxial compression test, or by a discrete element numerical simulation test of coal containing gas hydrates.
[0007] Optionally, the numerical simulation experiment is based on a discrete element model of coal containing gas hydrates. The discrete element model of coal containing gas hydrates includes multiple coal particles and multiple rigid clusters. Each rigid cluster represents a complete gas hydrate cemented agglomerate. The normal / tangential bonding strength between rigid clusters and between them and their adjacent coal particles is set to be lower than the normal / tangential bonding strength within the rigid cluster.
[0008] Optionally, in S2, the macroscopic damage constitutive relation is as follows: in, For stress, The initial elastic modulus, F 0 is the scale parameter. m This is the shape factor.
[0009] Optionally, in S3, the formula for the damage variable is: 1-exp(-(col(A) / F 0)^ m ) in, F 0 is the scale parameter. m Here, A is the shape factor, and A is the set fitting parameter.
[0010] Optionally, in S4, the second derivative of the damage variable formula is: Where D is the damage variable, ε In response, F 0 is the scale parameter. m This is the shape factor.
[0011] Optionally, in S5, the critical strain ratio is: in, ε _peak represents the peak strain. ε _c represents the critical strain.
[0012] Secondly, embodiments of the present invention also provide a device for obtaining critical values for damage deformation and failure prediction, comprising: Acquisition unit, used to obtain deviatoric stress-strain curves; The fitting unit is used to fit the pre-peak nonlinear stage of the deviatoric stress-strain curve based on the macroscopic damage constitutive relation, and to invert the characteristic parameters in the macroscopic damage constitutive relation: shape factor and scale parameter. A calculation unit is used to determine the damage variable formula based on the shape factor and the scale parameter; The derivative unit is used to calculate the second derivative of the damage variable formula and take the zero value to obtain the critical strain and critical damage. The ratio unit is used to determine the critical strain ratio based on the critical strain and peak strain, thus obtaining the critical value for characteristic damage warning.
[0013] Thirdly, embodiments of the present invention also provide an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the method described in any embodiment of this specification.
[0014] Fourthly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the methods described in any embodiment of this specification.
[0015] Compared with the prior art, the present invention has at least the following beneficial effects: In this embodiment, the specific values of characteristic parameters in the macroscopic damage constitutive relation can be determined by obtaining the deviatoric stress-strain curve. The strength of the gas hydrate-containing coal particle unit follows the Weibull statistical distribution function. According to the Weibull statistical distribution function, the corresponding macroscopic damage constitutive relation can be obtained. The fitted deviatoric stress-strain curve conforms to the macroscopic damage constitutive relation. Based on the fitted curve, the characteristic parameters in the macroscopic damage constitutive relation can be obtained by inversion. The obtained characteristic parameters can be used to establish a damage variable formula. By taking the second derivative of the damage variable formula, the critical strain and critical damage can be obtained. Then, the critical strain ratio can be determined by the ratio of the critical strain to the peak strain. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of a modeling process provided in an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the evolution law of shear bands provided in an embodiment of the present invention; Figure 3 This invention provides an experimental deviatoric stress-strain curve and a statistical damage constitutive model fitting curve. Figure 4 This is a damage variable-strain curve provided in an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the relationship between critical strain, peak strain, and confining pressure, as well as the stability of the critical strain ratio, provided by an embodiment of the present invention. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0019] This invention provides a method for obtaining critical values for damage, deformation, and failure prediction, comprising: S1, obtain the deviatoric stress-strain curve; S2, based on the macroscopic damage constitutive relation, the pre-peak nonlinear stage of the deviatoric stress-strain curve is fitted, and the characteristic parameters in the macroscopic damage constitutive relation are obtained by inversion: shape factor and scale parameter; S3, determine the damage variable formula based on the shape factor and the scale parameter; S4. Calculate the second derivative of the damage variable formula and take the zero value to obtain the critical strain and critical damage. S5. Determine the critical strain ratio based on the critical strain and peak strain, thus obtaining the critical value for characteristic damage warning.
[0020] In this embodiment, the specific values of characteristic parameters in the macroscopic damage constitutive relation can be determined by obtaining the deviatoric stress-strain curve. The strength of the gas hydrate-containing coal particle unit follows the Weibull statistical distribution function. According to the Weibull statistical distribution function, the corresponding macroscopic damage constitutive relation can be obtained. The fitted deviatoric stress-strain curve conforms to the macroscopic damage constitutive relation. Based on the fitted curve, the characteristic parameters in the macroscopic damage constitutive relation can be obtained by inversion. The obtained characteristic parameters can be used to establish a damage variable formula. By taking the second derivative of the damage variable formula, the critical strain and critical damage can be obtained. Then, the critical strain ratio can be determined by the ratio of the critical strain to the peak strain.
[0021] Of course, to increase the accuracy of the data, the critical strain ratio under different surrounding rock pressures can be obtained by using the method provided in this application, and then the average value can be calculated to obtain a more accurate critical value for damage warning.
[0022] In some embodiments of the present invention, in S1, the deviatoric stress-strain curve is obtained by fitting experimental data obtained from triaxial compression tests, or by numerical simulation tests of coal bodies containing gas hydrates.
[0023] Please refer to Figure 1In some embodiments of the present invention, the discrete element model of the coal containing gas hydrate includes multiple coal particles and multiple rigid clusters. A rigid cluster represents a complete gas hydrate cemented agglomerate. The normal / tangential bonding strength between rigid clusters and between them and their adjacent coal particles is set to be lower than the normal / tangential bonding strength inside the rigid cluster.
[0024] Existing models of porous media containing hydrates often simplify hydrates into small-diameter particles or static bonded contacts. However, these methods cannot accurately reproduce the complete process of deformation, breakage, disintegration, and structural reorganization (shear band formation) of real gas hydrates during loading in numerical simulations. In this embodiment, to more accurately simulate gas hydrate-containing coal bodies, rigid clusters are used to simulate hydrates within the coal body. By setting the bonding strength of the rigid clusters—specifically, setting the normal / tangential bonding strength between rigid clusters and between them and adjacent coal particles to be lower than the normal / tangential bonding strength within the rigid clusters—the rigid clusters can be used to simulate gas hydrates, simulating the cemented interface between gas hydrates and the coal body. This allows the rigid clusters to break under certain stress.
[0025] Furthermore, to ensure that during the initial loading process of the simulated sample, the contact between coal particles and the interface between adjacent gas hydrate particles preferentially fails, and the rigid cluster breaks down later, the normal and tangential bond strengths (σ_c_bond, τ_c_bond) within the rigid cluster can be set to be relatively high (other microscopic parameters of this model include: bond stiffness ratio, internal friction angle, cohesion, effective modulus, and coefficient of friction). Furthermore, to ensure that during the initial loading process of the simulated sample, the contact between coal particles and the interface between adjacent gas hydrate particles preferentially fails, and the rigid cluster breaks down later, the normal and tangential bond strengths within the rigid cluster can be set to be relatively high (σ_c_bond, τ_c_bond). , The coefficient of friction is relatively high (other micro-parameters of this model include: bond stiffness ratio, internal friction angle, cohesion, effective modulus, and coefficient of friction).
[0026] In some embodiments of the present invention, the numerical simulation experiment is based on a discrete element model of coal containing gas hydrates. The establishment of the discrete element model of coal containing gas hydrates includes: Randomly distributed coal particles and gas hydrate particles are generated inside a rigid body; an anti-rolling contact bonding model is used to characterize the influence of coal particle shape on the contact between coal particles and between adjacent hydrate particles to characterize the cementing effect of gas hydrate. Construct a circular wall and randomly generate multiple parallel contact bonding model particles inside it to obtain a rigid cluster; The rigid body's internal gas hydrate particles were replaced with the rigid clusters using the equal area method.
[0027] The specific process may include the following steps: (1) Preliminary construction of discrete element model of coal containing gas hydrate: a. Particle generation: Particles are generated inside a rectangular rigid wall with dimensions of 50mm × 100mm. Coal particles and gas hydrate particles are generated simultaneously and randomly distributed inside the wall.
[0028] b. Contact model assignment: The anti-rolling contact bonding model is used to characterize the influence of coal particle shape between coal particles, and the parallel contact bonding model is assigned to characterize the cementation effect of gas hydrate between hydrate particles and between adjacent particles.
[0029] (2) Modeling of gas hydrate "rigid clusters": a. Construct a circular wall with a diameter of 0.4 mm, and place sub-particles inside it. Assign a high-strength, irreversible parallel contact bond model between the sub-particles. Specifically, to ensure that during the initial loading process, the contact between coal particles and the interface between adjacent gas hydrate particles preferentially fails, and the rigid cluster breaks down later, the normal and tangential bond strengths within the rigid cluster are set (…). , The coefficient of friction is relatively high (other micro-parameters of this model include: bond stiffness ratio, internal friction angle, cohesion, effective modulus, and coefficient of friction).
[0030] b. Using the equal-area method, gas hydrate particles are replaced with rigid clusters to form breakable gas hydrate particles. Each rigid cluster represents a complete hydrate cemented agglomerate. The normal and tangential bond strengths imparted between rigid clusters and with adjacent coal particles (…) , The value is lower than the internal strength of the rigid cluster, which is used to simulate the cemented interface between gas hydrate and coal.
[0031] In some embodiments of the present invention, establishing a discrete element model of a coal body containing gas hydrates includes: Define the discrete element model of gas hydrate-containing coal bodies and the hydrate fragmentation event and shear zone germination evolution process.
[0032] In some embodiments of the present invention, the hydrate breakage event includes: when the external load applied to the rigid cluster exceeds its normal / tangential bond strength, the rigid cluster can be considered to have broken, and the rigid cluster is disintegrated into independent sub-particles by breaking the parallel contact bonds between all particles in the rigid cluster, so as to simulate the breakage of gas hydrate.
[0033] Please refer to Figure 2In some embodiments of the present invention, the shear band germination and evolution process includes: capturing and tracking the evolution of sample coordination number, porosity, contact force chain and particle rotation field during numerical simulation, defining and identifying the germination location and expansion process of the shear band.
[0034] After defining the above events and processes, a biaxial compression discrete element numerical simulation experiment can be carried out based on the two-dimensional discrete element model of gas hydrate-containing coal body that considers the fragmentation of gas hydrate particles constructed above.
[0035] In some embodiments of the present invention, S2 may specifically include the following steps: (1) Obtain the deviatoric stress-strain curves of coal samples containing gas hydrate under different confining pressures. The confining pressures were 10, 12 and 14 MPa, the peak stresses were 7.51 MPa, 10.04 MPa and 11.63 MPa, and the corresponding peak strains were 10.96%, 9.37% and 10.45%, respectively.
[0036] (2) The particle unit strength follows a Weibull statistical distribution function, and its probability density function is: F For the mechanical parameters of the micro-element; F 0 is the scale parameter, which controls the mean of the probability density function graph; m The shape factor controls the peak value of the probability density function graph.
[0037] Corresponding macroscopic damage constitutive relation: in, The initial elastic modulus is denoted by .
[0038] (3) Fit the pre-peak nonlinear stage of the deviatoric stress-strain curves under different confining pressures and invert to obtain its characteristic parameters, i.e. m and F 0 (Containing pressures of 10MPa, 12MPa, and 14MPa respectively, corresponding to) m The values are 0.491, 0.536, and 0.489 respectively. F (The values are 8.13, 4.10, and 3.58 respectively). A mathematical correlation is established between macroscopic experimental data and microscopic parameters, such as... Figure 3 As shown.
[0039] In some embodiments of the present invention, the specific process for S3 includes: Obtain three deviatoric stress-strain curves, and then repeat the above fitting and inversion operation to obtain the specimen size parameters under different confining pressures. F 0 and shape factorm .
[0040] Import the acquired strain and deviatoric stress values into Origin software (X-axis: strain value; Y-axis: deviatoric stress value), and input the damage variable formula "1-exp(-(col(A) / F 0)^ m (A can take the value 100), and then the software automatically generates damage variables. D and strain ε Finally, the damage variables are plotted. D With strain ε Changing curves, such as Figure 4 As shown.
[0041] In some embodiments of the present invention, for S4, the specific process includes: based on damage variables D -strain ε Given a curve, take its second derivative and find its zero point. The strain corresponding to this zero point is... ε Critical strain ε _c, the corresponding damage value is the critical damage. D _c (the critical point in the diagram): The critical strains corresponding to confining pressures of 10 MPa, 12 MPa, and 14 MPa were obtained. ε The critical damage values corresponding to _c are 4.30%, 3.88%, and 4.82%, respectively. D The values of _c are 0.61, 0.52, and 0.69, respectively. It can be seen that the critical damage value does not change monotonically, but the critical strain shows a trend of first decreasing and then increasing.
[0042] In some embodiments of the present invention, the specific process for S5 includes: a. To eliminate the dependence of absolute deviatoric stress or strain threshold on a specific confining pressure, a dimensionless universal criterion is proposed, namely the critical strain ratio. ,in ε _peak represents the peak strain under different confining pressures. By studying the evolution of critical damage values and critical strain, it can be concluded that the critical strain ratio is very stable, mainly concentrated between 39% and 46%.
[0043] b. Analyze the critical strain ratio under different confining pressures, and use the average value as the characteristic damage warning threshold for this material. 3 groups The average value is 0.42, which is the critical value for characteristic damage warning. It is 0.42.
[0044] Therefore, for particulate materials like coal containing gas hydrates, a strain loading to approximately 42% of the peak strain can be considered a precursor to macroscopic failure of the sample. Figure 5 As shown.
[0045] This invention provides a device for obtaining critical values for predicting damage, deformation, and failure. The device can be implemented in software, hardware, or a combination of both. From a hardware perspective, a hardware architecture diagram of the electronic device housing the device provided in this invention includes, in addition to the processor, memory, network interface, and non-volatile memory, other hardware such as a forwarding chip for processing packets. Taking software implementation as an example, as a logical device, it is formed by the CPU of the electronic device reading the corresponding computer program from the non-volatile memory into memory and running it. The device for obtaining critical values for predicting damage, deformation, and failure provided in this embodiment includes: Acquisition unit, used to obtain deviatoric stress-strain curves; The fitting unit is used to fit the pre-peak nonlinear stage of the deviatoric stress-strain curve based on the macroscopic damage constitutive relation, and to invert the characteristic parameters in the macroscopic damage constitutive relation: shape factor and scale parameter. A calculation unit is used to determine the damage variable formula based on the shape factor and the scale parameter; The derivative unit is used to calculate the second derivative of the damage variable formula and take the zero value to obtain the critical strain and critical damage. The ratio unit is used to determine the critical strain ratio based on the critical strain and peak strain, thus obtaining the critical value for characteristic damage warning.
[0046] It is understood that the structures illustrated in the embodiments of the present invention do not constitute a specific limitation on a damage, deformation, and failure prediction critical value acquisition device. In other embodiments of the present invention, a damage, deformation, and failure prediction critical value acquisition device may include more or fewer components than illustrated, or combine some components, split some components, or arrange different components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.
[0047] The information interaction and execution process between the modules in the above-mentioned device are based on the same concept as the method embodiment of the present invention, and the specific details can be found in the description of the method embodiment of the present invention, and will not be repeated here.
[0048] This invention also provides an electronic device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a method for obtaining critical values for damage deformation and failure prediction according to any embodiment of this invention.
[0049] This invention also provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program causes the processor to perform a method for obtaining critical values for damage deformation and failure prediction according to any embodiment of this invention.
[0050] Specifically, a system or apparatus equipped with a storage medium may be provided, on which software program code implementing the functions of any of the embodiments described above is stored, and the computer (or CPU or MPU) of the system or apparatus may read and execute the program code stored in the storage medium.
[0051] In this case, the program code read from the storage medium can itself implement the function of any of the above embodiments, and therefore the program code and the storage medium storing the program code constitute part of the present invention.
[0052] Storage media embodiments for providing program code include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, program code can be downloaded from a server computer via a communication network.
[0053] Furthermore, it should be clear that not only can the program code read by the computer be executed, but also the operating system or other components operating on the computer can be instructed based on the program code to perform some or all of the actual operations, thereby realizing the function of any of the embodiments described above.
[0054] Furthermore, it is understood that the program code read from the storage medium is written to the memory set in the expansion board inserted into the computer or to the memory set in the expansion module connected to the computer. Then, based on the instructions of the program code, the CPU or other components installed on the expansion board or expansion module execute some and all of the actual operations, thereby realizing the function of any of the above embodiments.
[0055] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0056] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as ROM, RAM, magnetic disk, or optical disk.
[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for obtaining critical values for damage, deformation, and failure prediction, characterized in that, include: S1, obtain the deviatoric stress-strain curve; S2, based on the macroscopic damage constitutive relation, the pre-peak nonlinear stage of the deviatoric stress-strain curve is fitted, and the characteristic parameters in the macroscopic damage constitutive relation are obtained by inversion: shape factor and scale parameter; S3, determine the damage variable formula based on the shape factor and the scale parameter; S4. Calculate the second derivative of the damage variable formula and take the zero value to obtain the critical strain and critical damage. S5. Determine the critical strain ratio based on the critical strain and peak strain, thus obtaining the critical value for characteristic damage warning.
2. The method according to claim 1, characterized in that, In S1, the deviatoric stress-strain curve is obtained by fitting experimental data from a triaxial compression test, or by numerical simulation test of coal containing gas hydrates.
3. The method according to claim 2, characterized in that, The numerical simulation experiment is based on the discrete element model of coal containing gas hydrates. The discrete element model of coal containing gas hydrates includes multiple coal particles and multiple rigid clusters. Each rigid cluster represents a complete gas hydrate cemented agglomerate. The normal / tangential bonding strength between rigid clusters and between them and their adjacent coal particles is set to be lower than the normal / tangential bonding strength within the rigid cluster.
4. The method according to claim 1, characterized in that, In S2, the macroscopic damage constitutive relation is as follows: in, For stress, The initial elastic modulus, F 0 is the scale parameter. m This is the shape factor.
5. The method according to claim 1, characterized in that, In S3, the formula for the damage variable is: 1-exp(-(col(A) / F 0)^ m ) in, F 0 is the scale parameter. m Here, A is the shape factor, and A is the set fitting parameter.
6. The method according to claim 1, characterized in that, In S4, the second derivative of the damage variable formula is: Where D is the damage variable, ε In response, F 0 is the scale parameter. m This is the shape factor.
7. The method according to claim 1, characterized in that, In S5, the critical strain ratio is: in, ε _peak represents the peak strain. ε _c represents the critical strain.
8. A device for obtaining critical values for predicting damage, deformation, and failure, characterized in that, For implementing the method as described in any one of claims 1-7, the apparatus comprises: Acquisition unit, used to obtain deviatoric stress-strain curves; The fitting unit is used to fit the pre-peak nonlinear stage of the deviatoric stress-strain curve based on the macroscopic damage constitutive relation, and to invert the characteristic parameters in the macroscopic damage constitutive relation: shape factor and scale parameter. A calculation unit is used to determine the damage variable formula based on the shape factor and the scale parameter; The derivative unit is used to calculate the second derivative of the damage variable formula and take the zero value to obtain the critical strain and critical damage. The ratio unit is used to determine the critical strain ratio based on the critical strain and peak strain, thus obtaining the critical value for characteristic damage warning.
9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, and the processor, when executing the computer program, implements the method as described in any one of claims 1-7.
10. A computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the method of any one of claims 1-7.