WO2015111917A1

WO2015111917A1 - Method and apparatus for concealing sound wave

Info

Publication number: WO2015111917A1
Application number: PCT/KR2015/000633
Authority: WO
Inventors: 안도열; 이용윤
Original assignee: 서울시립대학교산학협력단
Priority date: 2014-01-21
Filing date: 2015-01-21
Publication date: 2015-07-30
Also published as: KR20150086943A

Abstract

Disclosed is a method and apparatus for concealing sound waves. A method for concealing sound waves, according to an embodiment of the present invention, comprises the steps of: transforming a mathematical sound wave transmission model into a mathematical sound wave concealment model corresponding to a mathematical electromagnetic wave model on the basis of the correlation between the mathematical sound wave transmission model predetermined for sound wave transmission and the mathematical electromagnetic wave model predetermined for electromagnetic waves; deriving target characteristics of meta-material using the transformed mathematical sound wave concealment model; and shielding an area including a target object from sound waves by disposing the meta-material having the derived target characteristics to surround the area, wherein the mathematical electromagnetic wave model includes the mathematical model of Maxwell's equations, and the transforming of the mathematical sound wave transmission model includes transforming the mathematical sound wave transmission model into the mathematical sound wave concealment model by substituting the mathematical sound wave transmission model into a relativistic coordinate space transformation method on the basis of Maxwell's equations.

Description

Concealment method for sound waves and apparatus thereof

The present invention relates to a metamaterial, and more particularly, to a method and an apparatus capable of blocking transmission of sound waves to a specific region and blocking transmission of sound waves of a specific object by using the metamaterial.

Recent work on meta-materials has enabled microscopic and macroscopic control of electromagnetic fields [Phys. Rev. Lett. 85, 3966 (2000); Science 312, 1777 (2006); Science 312, 1780 (2006). Metamaterials are artificially created electromagnetic properties that are not found in the natural state. The peculiarity of metamaterials is that they have negative refractive indices, which cause the light to bend in the metamaterial as opposed to the direction it bends in ordinary materials. .

Using these metamaterials, it has been proposed to be able to adjust the direction of the electromagnetic field at will, irrespective of the source of the electromagnetic field, and to avoid and guide the object as if there are no objects [Science 312, 1777 (2006); Science 312, 1780 (2006). This can potentially be applied to radiation shielding from electromagnetic fields with strong magnetic field pulses (EMP) or directionality.

Electromagnetic field control using metamaterials is of great interest in the field of novel applications such as invisibility cloaks, concentrators, and refractors.

Among these, the invisibility cloak hides an object inside a given geometric shape, which is the most attractive application. The invisibility cloak is based on the coordinate transformation and conformal mapping of the Maxwell's equations, which are invisible to Pendry [Science 312, 1780 (2006)] and Leonhardt [Science 312, 1777 (2006). ] Are proposed independently by each.

Full wave electromagnetic simulation of cylindrical capes using ideal or non-ideal electromagnetic parameters has been studied, and experimental implementations of cylindrical capes with simple parameters operating at micro frequencies have been published.

In analyzing and designing the clearing device, it is most important to calculate the permittivity and transmittance tensors for the metamaterials that make up the transparent shell.

The invisibility device assumes that in some areas with uniform field lines, the field lines are distorted so that the field lines move away from the area, which is considered to be the coordinate transformation between the original Cartesian mesh and the distortion mesh. Can be.

Theoretical and experimental implementations of such a conventional transparent device were greatly influenced by the direction of propagation, polarization, and wavelength band of the electromagnetic wave. "Complementary media invisibility cloak that cloaks objects at a distance outside the cloaking shell," Y. Lai, H. Chen, Z. Q. Zhang, and C. Chan, Phys. Rev. Lett. 102, 93901 (2009). (Open date 2009.03.02) proposed a technique for improving the efficiency of an invisible cloak using complementary media, but the prior art reveals that it is effective at a finite frequency.

Attempts to overcome these limitations and extend to more general theories that can be applied in more general cases are described in "Calculation of permittivity tensors for invisibility devices by effective medium approach in general relativity", Doyeol Ahn, Journal of Modern Optics, Volume 58, Issue 8, 2011 (Publication Date 2011.04.01) and Korea Patent Publication No. 10-2013-0047860 (published date 2013.05.09).

The prior art approach allows the permittivity tensor and transmittance tensor to be scaled by factors obtained by coordinate transformation or optical conformal mapping techniques while maintaining the form of Maxwell's equations that do not change in any coordinate system.

In addition, a method of calculating the permittivity tensors and permeability tensors for transparent devices using electrodynamics in the frame of the theory of relativity was also studied.

The principle ideal of the prior art is based on the fact that the propagation of electromagnetic waves in curved space-time appears as wave traveling in an inhomogeneous effective bi-anisotropic medium. Its constitutive parameters are determined by the space-time metric.

This can represent the inverse problem of converting from a flat space-time medium to any curved space-time, and find specific conditions for invisibility cloaking.

The above-described prior arts are limited to a transparent technique in which the object of concealment is limited to electromagnetic waves, and the prior art that defines an object of concealment as an acoustic wave has not yet been realized.

The present invention is derived to solve the problems of the prior art as described above, by using a meta-material to block a specific region from the sound wave, exclude a specific region from the sound wave path, or the sound wave generated by a specific object is transmitted to the outside It is an object of the present invention to provide a sound wave concealment method and a device capable of blocking the interference.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for concealing sound waves, even when the sound wave concealment target region has various geometric shapes.

An object of the present invention is to provide a method and apparatus capable of concealing a specific region from sound waves irrespective of factors such as frequency or speed of the sound waves.

In order to achieve the above object, the sound wave concealment method according to an embodiment of the present invention is based on the correlation between the sound wave mathematical model predetermined for the sound wave transmission and the electromagnetic wave mathematical model predetermined for the wave propagation mathematical Converting a model into a sound wave concealment mathematical model corresponding to the electromagnetic wave mathematical model; Deriving a target property of a meta-material using the converted sound wave concealment mathematical model; And arranging the metamaterial having the derived target characteristic to surround an area including a target object to block the area from sound waves.

The electromagnetic wave mathematical model includes a mathematical model of Maxwell's equation, and the step of converting the acoustic wave concealment mathematical model into the acoustic wave propagation mathematical model to the Maxwell equation-based relativistic coordinate space transformation method to convert the sound wave mathematical model The sound wave concealment can be converted into a mathematical model.

The mathematical model of the Maxwell equation may be a mathematical model of the Maxwell equation for an elliptic coordinate system or a mathematical model of the Maxwell equation for a bipolar coordinate system.

The converting of the acoustic wave concealment mathematical model to the electromagnetic wave mathematical model is based on a one-to-one correspondence between each term of the acoustic wave mathematical model and each term of the electromagnetic wave mathematical model with respect to two-dimensional coordinates. Can be converted to the corresponding acoustic wave concealment mathematical model.

In the sound wave concealment device according to an embodiment of the present invention, in the sound wave concealment device that blocks sound waves using a meta material, the meta material has a target characteristic derived using a predetermined sound wave concealment mathematical model, and blocks sound waves. And a sound wave concealment mathematical model based on a correlation between a sound wave mathematical model predetermined for sound wave transmission and a electromagnetic wave mathematical model predetermined for electromagnetic wave. Correspondingly determined from the sonic transfer mathematical model is determined to correspond.

The electromagnetic wave mathematical model includes a mathematical model of Maxwell's equation, and the acoustic wave concealment mathematical model may be determined by converting the acoustic wave transfer mathematical model into the Maxwell's equation-based relativistic coordinate space transformation method to be converted from the acoustic wave mathematical model. have.

According to the present invention, using a meta-material having a target characteristic derived by substituting a mathematical model for sound wave propagation into a Maxwell's equation-based relativistic method of spatial transformation, a sound wave generated from a specific object is blocked or blocked from a specific region. Can block the transmission to the outside.

In addition, according to the present invention, it is possible to isolate the object or a specific area from the sound waves, it is possible to isolate the noise source, to block the sound waves in the desired area, to reduce the noise between the floors of the apartment, ships or submarines, etc. It can be applied in principle to reduce the noise level of

According to the present invention, even when the sound wave concealment target region has various geometric shapes such as an elliptic cylindrical shape and a bipolar cylindrical shape, the characteristics of the metamaterial capable of sound concealment can be derived accordingly.

According to the present invention, it is possible to derive the characteristics of the meta-material which can conceal a specific region from the sound wave irrespective of factors such as frequency or speed of the sound wave.

1 shows an example of a transparent cloak based on a method of space-time metamaterial analysis based on a general theory of relativity.

2 is a flowchart illustrating an operation of an acoustic wave concealment method according to an embodiment of the present invention.

3 illustrates a configuration of a sound wave concealment apparatus for an elliptic coordinate system according to an embodiment of the present invention.

4 illustrates a clocking result for the sound wave concealment apparatus of FIG. 3.

5 illustrates a configuration of a sound wave concealment apparatus for a bipolar coordinate system according to an embodiment of the present invention.

FIG. 6 illustrates a clocking result for the sound wave concealment apparatus of FIG. 5.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

However, the present invention is not limited or limited by the embodiments. Like reference numerals in the drawings denote like elements.

Hereinafter, a method and apparatus for shielding sound waves according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6.

In this specification, meta-materials are defined as follows. Metamaterial is used to mean a material that can artificially control or design a tensor of dielectric constant and permeability, or a material obtained as a result of control or design.

Invisibility devices are based on the theoretical argument that if Maxwell's equations are established in space-time with finite curvature, the curvature of space-time acts as permittivity and permeability for electric and magnetic fields. do.

Specifically, the covariant Maxwell equation in general relativity can be expressed as Equation 1 below.

[Equation 1]

Where ";" in the subscript means a covariant derivative, ε ₀ means permittivity in free space, and μ, ν, λ denote each component in the four-dimensional coordinate space in any four-dimensional coordinate system ( component).

g denotes a determinant of the metric tensor g _μν , J denotes a current density, and F _μν denotes an electromagnetic field tensor.

Equation 1 is disclosed in Korean Patent Publication No. 10-2013-0047860 (published on May 09, 2013) and "Calculation of permittivity tensors for invisibility devices by effective medium approach in general relativity", Doyeol Ahn, Journal of Modern Optics , Volume 58, Issue 8, 2011 (published 2011.04.01) introduces the derivation process. In addition, the derivation process for a number of equations derived below is also introduced in the prior art. Therefore, the present specification will be briefly described in a range not obscure the subject matter of the present invention with the main content adopted in the present invention.

In this case, the electromagnetic field tensor may be represented by Equation 2 below. In the general theory of relativity, electromagnetic tensors are described in the form of matrices for three dimensions: zero (time) and space.

[Equation 2]

Here, E means the electric field, x, y, z means the direction, B means the electric flux (electric flux).

In addition, the contra-variant tensor H ^μν may be represented by Equation 3 below, and Equation 3 may be defined as Equation 4 below.

[Equation 3]

[Equation 4]

Here, H means magnetic field and D means magnetic flux.

Summarizing the above equations, the following equations (5) and (6) can be obtained.

[Equation 5]

[Equation 6]

Where [ijk] is an anti-symmetric permutation symbol, defined as [xyz] = 1, μ ₀ is the transmittance in free space, and g ^ab is the (a , b) means component, and g _cd means (c, d) component of the covariate metric tensor.

As can be seen from the above equation, it can be seen that Maxwell's equation in vacuum having a finite radius of curvature can be interpreted as Maxwell's equation in a medium having finite permittivity and transmittance.

FIG. 1 shows an example of a transparent cloak based on a space-time metamaterial analysis method based on a general relativity theory. In the physical space, an empty space in the middle represents a space for hiding a given object.

In addition, the virtual space refers to a space in which an empty space of a physical space is converted into a point at the center. Using this relationship, an intuitive picture of the transparent cloak can be created by using the coordinate transformation between the two space-times, physical space and virtual space that will actually implement invisibility cloaking. Coordinate transformations between these two spaces can be described as metric tensors in space-time (g _μν ) and are metric tensors that represent the curvilinear coordinates of physical space.

In this case, the conversion equation between the two spaces is given by Equation 7 below, and the permittivity tensor (ε ^ij ) and transmittance tensor (μ ^ij ) of the physical space to be realized as metamaterials can be expressed as Equation 8 below. have.

[Equation 7]

[Equation 8]

here,

Is

Means,

^kk is 1 /

_kk means

However, the transparent cloak implemented in this way has the disadvantage of maximizing the efficiency of the transparent when the electromagnetic wave is polarized in a specific direction.

The invention is published in papers already published by the inventor of the invention [J. Mod. Opt. 58, 700-710 (2011), Journal of the Korean Physical Society 60, 1349-1360 (2012), JOSA B 30, 140-148 (2013). Using the Maxwell's equation-based relativistic coordinate space transformation method, we derive the acoustic wave concealment mathematical model to block the sound wave or to make the sound wave transparent from the mathematical model for the sound wave transmission. By deriving the target properties of meta-materials, the main point is to make specific areas transparent from sound waves or block sound waves to specific areas.

Referring to FIG. 2, the method according to the present invention corresponds a sonic wave mathematical model for sonic wave propagation and an electromagnetic wave mathematical model for electromagnetic wave, and generates a sonic wave mathematical model based on the correlation between the sonic wave mathematical model and the electromagnetic wave mathematical model. A sound wave concealment mathematical model corresponding to the electromagnetic wave mathematical model is converted (S210 and S220).

Here, the electromagnetic mathematical model is a mathematical model of the Maxwell's equation, and may include a mathematical model of the Maxwell's equation for an elliptic coordinate system or a mathematical model of the Maxwell's equation for a bipolar coordinate system, and the acoustic concealment mathematical model has a relativistic coordinate based on the Maxwell's equation. By incorporating a sonic transmission mathematical model into the spatial deformation method, it can be converted from a sonic transmission mathematical model.

The sound wave equation for the sound wave mathematical model can be expressed as Equation 9 below.

[Equation 9]

Where p means pressure,

Is the velocity vector of the fluid, ρ is the mass of the fluid or medium, and λ is the bulk modulus of the fluid or medium.

The sonic equation has a one-to-one correspondence to a specific polarization with Maxwell's equation, which is an electromagnetic model in the two-dimensional case, and based on this correlation, the transparent cloak method for electromagnetic waves can be used.

The sonic equation can be expressed as Equation 10 below with respect to generalized curvilinear coordinates q ₁ , q ₂ and q ₃ .

[Equation 10]

here

Denotes a unit vector (i = 1, 2, 3) in the q _i axis direction, and h _i denotes a metric for indicating a distance between two points on the q _i axis.

For convenience, assuming symmetry about the z axis in two dimensions, q ₃ = z, h ₃ = 1 and

In the case of time-harmonic, the sound wave equation may be expressed as Equation 11 below.

[Equation 11]

Maxwell's equation for the electromagnetic field can be expressed as

It can be expressed as in Equation 13 below.

[Equation 13]

In the case of the time harmonic for the TE (transverse electric) waves (H ₁ , H ₂ , E _z ), the following Equation 14 can be obtained from Equations 12 and 13 below.

[Equation 14]

Comparing Equation 11 and Equation 14, when the variables for the acoustic wave equation and the variables for the electromagnetic wave equation have a one-to-one correspondence as shown in Equation 15 below, the equations are equivalent. It can be seen that it has.

[Equation 15]

The mathematical model of the sound wave may be converted into a sound wave concealment mathematical model corresponding to the electromagnetic wave mathematical model using the relational expression of Equation 15.

As such, the present invention is described in papers already published by the inventor of the present invention [J. Mod. Opt. 58, 700-710 (2011), Journal of the Korean Physical Society 60, 1349-1360 (2012), JOSA B 30, 140-148 (2013), JOSA B 30, 2148 (2013). By substituting the sonic propagation mathematical model into the method of relativistic coordinate-space transformation of Maxwell's equations, sound waves can be blocked.

Referring back to FIG. 2, by substituting the acoustic wave propagation mathematical model into the Maxwell's equation-based relativistic coordinate space transformation method, the target characteristic of the metamaterial is derived using the acoustic wave concealment mathematical model converted from the acoustic wave propagation mathematical model (S230). ).

Here, the target properties of the metamaterial may include the density of the fluid or the mass of the medium, the volume modulus of the fluid or the medium, and the like.

By placing the meta-material having the target characteristic derived in step S230 so as to surround the area including the object, the sound wave is blocked by using the meta-material, and thus, the sound wave proceeding to the area including the object is blocked or the object Sound waves generated from the area including the object may be blocked from going out (S240, S250).

The object to be used in the present invention may be a spatial concept or an object corresponding to a noise source.

As such, the sound wave concealment method according to the present invention substitutes the mathematical model of the sound wave into a relativistic coordinate space transformation method based on Maxwell's equation, and converts the sound wave transfer mathematical model to the sound wave concealment mathematical model and uses the converted sound wave concealment mathematical model. By deriving the target property of the metamaterial, the sound wave may be blocked by using the metamaterial having the derived target property.

In the present invention, a sound wave concealment apparatus of an elliptic coordinate system and a bipolar coordinate system will be described as follows.

1) Sound wave concealment device in elliptic coordinate

FIG. 3 shows an example of a sound wave concealment apparatus of an elliptic cylindrical coordinate, and the relationship between the independent variables (u, v, z) and the Cartesian coordinate system (x, y, z) of the elliptic cylindrical coordinate is Equation 16 may be expressed as follows.

[Equation 16]

Here, (a, 0) and (-a, 0) shown in FIG. 3 mean a focus in an elliptic coordinate system.

As shown in FIG. 3, the primed coordinate system for the empty curved space-time (assuming that the area to be protected is u <U ₁ and the metamaterial 310 constituting the transparent device is disposed within U ₁ <u <U ₂ ) Using primed coordinates, the physical medium may be defined as in Equation 17 below.

In this case, the coordinate system used may be a generalized cylindrical coordinate.

[Equation 17]

Where U ₁ and U ₂ mean a predetermined value of a region of metamaterial, u 'means distance in virtual space, u means distance in physical space, and ν' is in virtual space Denotes a generalized angle or distance of ν, ν denotes a generalized angle or distance in physical space, and z and z 'denote a distance (height) in the z direction in physical space and virtual space.

In the general relativity theory, the permittivity and permeability for implementing an elliptic cylindrical transparent cloak from an effective medium approach can be expressed by Equation 18 below.

Equation 18

Here, diag () may denote a diagonal matrix, and ε ⁱ _j and μ ⁱ _j may refer to permittivity tensors and transmittance tensors in an elliptic cylindrical coordinate system.

Through Equations 15 and 18, the conditions for implementing the sound wave concealment method or apparatus in an elliptic coordinate system are shown in Equation 19 below.

[Equation 19]

That is, as can be seen from Equation 19, it can be seen that the target characteristic for the meta-material in the elliptic coordinate system can be derived by using the sonic concealment mathematical model converted from the sonic transmission mathematical model.

By arranging a meta-material having a target characteristic derived using Equation 19 to surround the target region, the target region may be protected from sound waves.

The acoustic wave concealment method or device for the elliptic coordinate system is as shown by the numerical analysis results shown in Figs. 4A and 4B, so that sound waves or pressure waves traveling in the x- and y-axis directions do not reach the inner region of the elliptic cylinder. As can be seen, according to the present invention, it is possible to fundamentally block sound waves in a desired area as well as to isolate the noise source, and can be applied in principle to alleviating the noise level between the floors of apartments and reducing the noise level of ships or submarines.

2) Acoustic wave concealment device in bipolar coordinates

FIG. 5 illustrates an example of a sound wave concealment apparatus of a bipolar cylindrical coordinate system, and the relationship between the independent variables (σ, τ, z) and the Cartesian coordinate system (x, y, z) of the bipolar cylindrical coordinate system is below < Equation 20 may be expressed as follows.

[Equation 20]

Where σ is the angle or generalized distance in physical space, τ is the ratio of the distance to angle σ at any point P of the bipolar cylindrical coordinate system in physical space, and the range of σ is

τ range is

And the range of z is

Can be.

In the case of a bipolar cylindrical cloak, a region or a target region to which the object to be transparent belongs may be represented by using a bipolar cylindrical coordinate.

At this time, the target object or target region to be protected is disposed at σ ₁ <σ <2π−σ ₁ , and the metamaterial 510 constituting the transparent device is

May be placed in the area. Here, sigma refers to an angle or generalized distance in physical space, and sigma ₁ and sigma ₂ represent a predetermined angle or generalized distance in physical space.

Therefore, the map of the bipolar cylindrical coordinate system can be defined by Equation 21 below.

[Equation 21]

Where σ 'denotes an angle in virtual space, σ denotes an angle in physical space, and τ and τ' denote angles σ and σ at any point P of the bipolar cylindrical coordinate system in physical and virtual space. 'Is the ratio of distances (d ₁ , d ₂ ) to those of skill in the art, such as information about bipolar coordinate systems ( https://en.wikipedia.org/wiki/Bipolar_coordinates, etc.). Information) and the relationship between the virtual space and the physical space of FIG. 1.

Therefore, the configuration parameters for the bipolar cylindrical transparent device or transparent cloak can be obtained as shown in Equation 22 below.

[Equation 22]

Here, ε ⁱ _j and μ ⁱ _j mean permittivity tensor and transmittance tensor in bipolar cylindrical coordinate system.

Through Equation 15 and Equation 22, the conditions for implementing the sound wave concealment method or device in an elliptic coordinate system are shown in Equation 23 below.

[Equation 23]

That is, as can be seen from Equation 23, it can be seen that the target characteristic for the meta-material in the bipolar coordinate system can be derived using the acoustic concealment mathematical model converted from the acoustic wave transmission mathematical model.

By arranging the metamaterial having the target characteristic derived using Equation 23 to surround the target region, the target region may be protected from sound waves.

The acoustic wave concealment method or apparatus for the bipolar coordinate system can be understood from the numerical analysis results shown in FIGS. 6A and 6B, where sound waves or pressure waves traveling in the x- and y-axis directions do not reach the inner region of the bipolar cylinder. As can be seen, according to the present invention, it is possible to fundamentally block sound waves in a desired area as well as to isolate the noise source, and can be applied in principle to alleviating the noise level between the floors of apartments and reducing the noise level of ships or submarines.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents and equivalents of the claims, as well as the following claims, will fall within the scope of the present invention. .

A sound wave concealment method and apparatus thereof are disclosed. The acoustic wave concealment method according to an embodiment of the present invention corresponds to the electromagnetic wave mathematical model by converting the acoustic wave mathematical model to the electromagnetic wave mathematical model based on a correlation between the acoustic wave mathematical model predetermined for sound wave transmission and the electromagnetic wave mathematical model predetermined for the electromagnetic wave. Converting to an acoustic concealment mathematical model; Deriving a target property of a meta-material using the converted sound wave concealment mathematical model; And disposing the meta-material having the derived characteristic to enclose an area including a target object to block the area from sound waves, wherein the electromagnetic mathematical model includes a mathematical model of Maxwell's equation, The converting of the sound wave concealment mathematical model may include converting the sound wave transfer mathematical model into the sound wave concealment mathematical model by substituting the sound wave transfer mathematical model into the Maxwell's equation-based relativistic coordinate space transformation method.

Claims

Converting the sound wave mathematical model into a sound wave concealment mathematical model corresponding to the electromagnetic wave mathematical model based on a correlation between the sound wave mathematical model predetermined for sound wave transmission and the electromagnetic wave mathematical model predetermined for the electromagnetic wave;

Deriving a target property of a meta-material using the converted sound wave concealment mathematical model; And

Placing the meta-material having the derived target characteristic so as to surround an area including a target object to block the area from sound waves.

Sound wave concealing method comprising a.
The method of claim 1,

The electromagnetic model is

Contains a mathematical model of the Maxwell equation,

The conversion to the acoustic concealment mathematical model

And substituting the sonic propagation mathematical model into the Maxwell's equation-based relativistic coordinate space transformation method to convert the sonic propagation mathematical model into the sonic concealment mathematical model.
The method of claim 2,

The mathematical model of the Maxwell equation is

A mathematical model of the Maxwell equation for an elliptic coordinate system or a mathematical model of the Maxwell equation for a bipolar coordinate system.
The method of claim 1,

The conversion to the acoustic concealment mathematical model

Converting the sound wave mathematical model to the sound wave concealment mathematical model corresponding to the electromagnetic wave mathematical model based on a one-to-one correspondence between each term of the sound wave mathematical model and each term of the electromagnetic wave mathematical model for two-dimensional coordinates. A sound wave concealment method, characterized in that.
In the sound wave concealment device that blocks the sound wave by using meta-material,

The meta-material is

Having a target characteristic derived using a predetermined sound wave concealment mathematical model, and arranged to surround an area including a target object for blocking sound waves,

The acoustic concealment mathematical model

Based on a correlation between a predetermined sound wave mathematical model for sound wave transmission and a predetermined electromagnetic wave electromagnetic wave model for electromagnetic waves,

A sound wave concealment device, characterized in that.
The method of claim 5,

The electromagnetic model is

Contains a mathematical model of the Maxwell equation,

The acoustic concealment mathematical model

And substituting the sonic transmission mathematical model into the Maxwell's equation-based relativistic coordinate space transformation method.
The method of claim 6,

The mathematical model of the Maxwell equation is

A acoustic concealment device, characterized in that it is a mathematical model of the Maxwell's equation for an elliptic coordinate system or a mathematical model of the Maxwell's equation for a bipolar coordinate system.
The method of claim 6,

The acoustic concealment mathematical model

Characterized in that the two-dimensional coordinates are converted from the sonic wave mathematical model to be determined based on the one-to-one correspondence between each term of the sonic wave mathematical model and each term of the electromagnetic wave mathematical model. Sonic concealment device.