Method for approximately calculating microalgae radiation characteristics based on discrete dipole

Abstract

The invention discloses a method for approximately calculating microalgae radiation characteristics based on discrete dipoles, which mainly relates to the field of microalgae radiation and comprises the following steps: S1, selecting algae species; s2, analyzing structures and components of the microalgae, and determining optical constants of the components; s3, constructing a microalgae cell model according to the structure and the components; s4, calculating algae radiation characteristics of the microalgae model by using a discrete dipole approximation method; s5, comparing the calculation result with the actually measured radiation characteristic parameter to verify the accuracy of calculating the microalgae radiation characteristic based on the discrete dipole approximation method; the problem that in the prior art, the radiation characteristic parameters of the microalgae cannot be accurately obtained due to the experiment cost problem and the limitation of an existing calculation method is solved.

Description

Technical Field

[0001] The invention relates to the field of microalgae radiation, and in particular to a method for calculating microalgae radiation characteristics based on discrete dipole approximation. Background Art

[0002] Microalgae has a variety of industrial application values ​​and has high photosynthetic efficiency. Therefore, it is considered to be an ideal raw material for biomass energy. Large-scale industrial production of microalgae is usually carried out in photobiological reaction vessels. The radiation characteristics of microalgae cells are the basis for studying the light intensity distribution of reaction vessels and provide an important basis for the optimal design of photoreactors. However, due to experimental cost issues and the limitations of existing calculation methods, the radiation characteristic parameters of microalgae cannot be accurately obtained. The existing methods for obtaining the radiation characteristics of microalgae are mostly experimental, and the cost of experimental equipment is relatively high. The methods for obtaining the radiation characteristics of microalgae through simulation calculations include Mie theory, T matrix, etc., but they cannot well reflect the actual radiation characteristics of microalgae, and the accuracy needs to be improved. Summary of the invention

[0003] The purpose of the present invention is to solve the problem in the prior art that the radiation characteristic parameters of microalgae cannot be accurately obtained due to experimental cost issues and the existing calculation methods are limited by themselves, and to provide a method for calculating the radiation characteristics of microalgae based on discrete dipole approximation.

[0004] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for calculating the radiation characteristics of microalgae based on discrete dipole approximation comprises the following steps:

[0006] S1. Select algae species;

[0007] S2. Analyze the structure and components of microalgae and determine the optical constants of each component;

[0008] S3. Construct a microalgae cell model based on structure and components;

[0009] S4. Calculate the algae radiation characteristics of the microalgae model using the discrete dipole approximation method;

[0010] S5. Compare the calculated results with the actually measured radiation characteristic parameters to verify the accuracy of calculating the radiation characteristics of microalgae based on the discrete dipole approximation method.

[0011] Preferably, in step S2: literature on target algae species with FIB-SEM scanning electron microscope images and specific parameters is searched by reading, or the required structure and parameters are obtained by experiments.

[0012] Preferably, in step S2: the structure is the real internal and external structure of the microalgae, and the parameters include the actual size of each component of the microalgae and the optical constants of each component, and the components include cell wall, cell nucleus, mitochondria and chloroplasts.

[0013] Preferably, in step S3: a microalgae cell model is constructed using MATLAB or 3DMAX software.

[0014] Preferably, in step S4: the radiation characteristics of the microalgae include: absorption cross section, scattering cross section and scattering phase function.

[0015] Preferably, the calculation process of step S4 is:

[0016] First, the scatterer is decomposed into N dipoles, each with a polarizability of α j , the coordinate is r j (j=1,2,3…N), the electric field where the model is located is E j , then the dipole moment of this point is P j for:

[0017]

[0018] Among them, E j A is the sum of the incident electric field in the calculation area and the scattering of the remaining dipoles. jk It is a 3×3 matrix, expressed as:

[0019]

[0020] Where, k = 2π / λ (λ is the incident wavelength), r jk =|r j -r k |, r jk =(r j -r k ) / r jk , I is the third-order unit matrix;

[0021] Then, let Then the dipole moment P j Satisfies 3N complex linear equations:

[0022]

[0023] So we can solve P k , the dipole moment is P k , and thus the scatterer's C ext , C sca and C abs , the formula corresponding to the absorption cross section is:

[0024]

[0025] The formula corresponding to the extinction cross section is:

[0026]

[0027] The formula corresponding to the scattering cross section is:

[0028] C sca =C ext -C abs ;

[0029] Among them, E0 is the amplitude of the incident electric field; r is the distance from the source point to the field point.

[0030] Preferably, the number of dipoles per wavelength is greater than ten.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] The present invention adopts a discrete dipole approximation method in the field of microalgae radiation to make up for the accuracy and applicability of the microalgae radiation characteristic calculation accuracy, improve the accuracy of the microalgae radiation characteristic parameters and the accuracy of the microalgae radiation characteristic parameters with irregular internal and external structures; and compared with the experiment, the present invention improves its economy while ensuring accuracy. The problem of experimental cost and the inability of the existing calculation method to accurately obtain the radiation characteristic parameters of microalgae due to its own limitations is solved. The discrete dipole approximation method is used to make the model details perform well, the theoretical calculation results are highly accurate, and the scope of application is wide. It can take into account both the appearance and the internal structure at the same time, and is not limited to spherical and quasi-spherical shapes. The calculated microalgae radiation characteristics can be more accurately close to the experimental parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is the technical roadmap of the present invention;

[0034] Figure 2 This is a microalgae cell model for DDA calculation built using MTATLAB, taking Chlamydomonas reinhardtii as an example;

[0035] Figure 3 This is a comparison of the absorption cross sections of Chlamydomonas reinhardtii calculated by different models and the experimental results;

[0036] Figure 4 This is a comparison of the scattering cross sections of Chlamydomonas reinhardtii calculated by different models and the experimental results;

[0037] Figure 5 This is a comparison of the scattering phase function of Chlamydomonas reinhardtii calculated by different models and the experimental results. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.

[0039] Example: As attached Figure 1 As shown, the present invention is a method for calculating the radiation characteristics of microalgae based on discrete dipole approximation, comprising the steps of:

[0040] S1. Select the algae species to be used in the calculation. Different algae species have different structures and components. There are more than 40,000 kinds of microalgae in the world, such as Figure 1 As shown in the technical route, the target algae species for which radiation characteristics calculation is to be performed is first selected according to the needs.

[0041] S2. After determining the algae species, analyze the structure and components of the microalgae and determine the optical constants of each component.

[0042] Specifically, we can find target algae species literature with FIB-SEM images and specific parameters, or obtain the required structure and parameters through experiments. The required parameters include the actual size of each component of the microalgae and the optical constants of each component (such as cell wall, nucleus, mitochondria, chloroplasts, etc.).

[0043] S3. According to the observed structure and components, the microalgae cell model is constructed using MATLAB or 3DMAX software. Since the DDA method has a wide range of applications and good model detail performance, both rule-based simplified models and complex and detailed models can be used in model construction.

[0044] S4. Calculate the radiation characteristics of the microalgae model using discrete dipole approximation. The radiation characteristics of the microalgae mainly include: absorption cross section, scattering cross section and scattering phase function;

[0045] Specifically, the basic principle of discrete dipole approximation calculation is to regard the continuous scattering object as an array of finite dipoles. Each dipole in the array obtains the dipole moment by responding to the electric field in the calculation area, including the incident field and the radiation field of other points. The sum of the radiation of all points on the scatterer in the far field constitutes the scattering field.

[0046] This embodiment uses ADDA v.1.5.0 developed by Maxim A. Yurkin and Alfons G. Hoekstra. In DDA calculation, in order to ensure the accuracy of the results, it is usually required that the number of dipoles per wavelength is greater than 10.

[0047] |m|kd is an important parameter in the calculation process. To ensure accuracy, it is assumed that the scatterer is decomposed into N dipoles, and the polarizability of each dipole is α j , the coordinate is r j (j=1,2,3…N), the electric field where the model is located is E j , then the dipole moment of this point is P j for:

[0048]

[0049] In the above formula, E j is the sum of the incident electric field in the calculation area and the scattering of the remaining dipoles, where A jk It is a 3×3 matrix, expressed as:

[0050]

[0051] In the above formula, k = 2π / λ (λ is the incident wavelength), r jk =|r j -r k |, r jk =(r j -r k ) / r jk , I is the third-order unit matrix.

[0052] make Then the dipole moment P j Satisfies 3N complex linear equations:

[0053]

[0054] So we can solve P k , the dipole moment is P k , and thus the scatterer's C ext , C sca and C abs , the formula corresponding to the absorption cross section in step S4 is:

[0055]

[0056] The extinction (attenuation) cross section is:

[0057]

[0058] The scattering cross section is:

[0059] C sca =C ext -C abs

[0060] Where: E0 is the amplitude of the incident electric field, and r is the distance from the source point to the field point.

[0061] S5. Compare the calculated parameters with the actually measured radiation characteristic parameters to verify the accuracy of calculating the radiation characteristics of microalgae based on the discrete dipole approximation method.

Claims

1. A method for calculating the radiation characteristics of microalgae based on discrete dipole approximation, characterized in that: Includes steps: S1. Select algae species; S2. Analyze the structure and components of microalgae and determine the optical constants of each component; S3. Construct a microalgae cell model based on structure and components; S4. Calculate the algae radiation characteristics of the microalgae model using the discrete dipole approximation method; S5. Compare the calculated results with the actually measured radiation characteristic parameters to verify the accuracy of calculating the radiation characteristics of microalgae based on the discrete dipole approximation method.

2. The method for calculating the radiation characteristics of microalgae based on discrete dipole approximation according to claim 1, characterized in that: In step S2: searching for target algae species literature with FIB-SEM scanning electron microscope images and specific parameters by reading, or obtaining the required structure and parameters through experiments.

3. A method for calculating the radiation characteristics of microalgae based on discrete dipole approximation according to claim 1 or 2, characterized in that: In step S2: the structure is the real internal and external structure of the microalgae, and the parameters include the actual size of each component of the microalgae and the optical constants of each component, and the components include cell wall, cell nucleus, mitochondria and chloroplasts.

4. The method for calculating the radiation characteristics of microalgae based on discrete dipole approximation according to claim 1, characterized in that: In step S3: construct a microalgae cell model using MATLAB or 3DMAX software.

5. The method for calculating the radiation characteristics of microalgae based on discrete dipole approximation according to claim 1, characterized in that: In step S4: the radiation characteristics of the microalgae include: absorption cross section, scattering cross section and scattering phase function.

6. The method for calculating the radiation characteristics of microalgae based on discrete dipole approximation according to claim 1, characterized in that: The calculation process of step S4 is: First, the scatterer is decomposed into N dipoles, each with a polarizability of α j , the coordinate is r j (j=1,2,3…N), the electric field where the model is located is E j , then the dipole moment of this point is P j for: Among them, E j A is the sum of the incident electric field in the calculation area and the scattering of the remaining dipoles. jk It is a 3×3 matrix, expressed as: Where, k = 2π / λ (λ is the incident wavelength), r jk =|r j -r k |, r jk =(r j -r k ) / r jk , I is the third-order unit matrix; Then, let Then the dipole moment P j Satisfies 3N complex linear equations: So we can solve P k , the dipole moment is P k , and thus the scatterer's C ext , C sca and C abs , the formula corresponding to the absorption cross section is: The formula corresponding to the extinction cross section is: The formula corresponding to the scattering cross section is: C sca =C ext -C abs ; Among them, E0 is the amplitude of the incident electric field; r is the distance from the source point to the field point.

7. The method for calculating the radiation characteristics of microalgae based on discrete dipole approximation according to claim 6, characterized in that: The number of dipoles per wavelength is greater than 10.

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