22 results about "Primitive cell" patented technology

The invention discloses a method for researching the corrosion resistance behavior of zinc alloy based on a first principle. The method comprises the following steps: firstly, retrieving a zinc primitive cell model from a material database and carrying out structure optimization; performing crystal face cutting, cell expansion and re-structure optimization to obtain a zinc plate model; then aluminum atom random replacement doping processing is carried out, and optimization is carried out to obtain a doping model; performing static self-consistent calculation to obtain surface energy, and screening out the most stable doping model; fixing two layers of atoms at the bottom of the most stable doping model, performing chloride ion adsorption calculation and structure optimization, and calculating adsorption energy to determine a most stable adsorption site; and finally, carrying out electronic structure calculation of state density and a work function, and representing the corrosion resistance of the zinc alloy. According to the method, a zinc alloy corrosion micromechanism is deeply analyzed, theoretical guidance is provided for component optimization and corrosion resistance improvement, and compared with a traditional experimental method, the research and development cost and time are remarkably reduced, the research efficiency is improved, and the method has important theoretical and practical application value.

The invention provides a nonlinear ultrasonic detection method and device based on a photonic crystal, and relates to the technical field of nonlinear ultrasonic detection.The photonic crystal structurally comprises rectangular protrusions and a main board, and the upper surface and the lower surface of the main board are each provided with a plurality of identical rectangular protrusions periodically arranged in the transverse direction; primitive cells of the phononic crystal are formed by symmetrically attaching rectangular protrusions to the upper surface and the lower surface of a main board, and the method comprises the steps that the energy band structure of phonons and crystals is calculated through a constructed finite element model of the primitive cells of the phononic crystal, and the passband range and the forbidden band range of the phononic crystal are analyzed; in nonlinear ultrasonic detection of damage of a material, the photonic crystal is attached to the material, propagation of second harmonics generated nonlinearly by a system is prevented through a forbidden band range, and fundamental waves pass through a passband range. Therefore, through the attached photonic crystal, the nonlinear wave of the system is effectively filtered to reduce the influence of nonlinear ultrasonic detection, and the accuracy and sensitivity of the nonlinear ultrasonic detection are improved.

The invention provides a three-dimensional photonic crystal fiber device based on triple spiral dislocation, which comprises a plurality of primitive cells periodically arrayed along a Z direction, and the primitive cells are of honeycomb lattice structures and are equally divided into three areas in an X-Y plane; wherein the area I comprises a plurality of first structure units which are periodically arrayed in an X-Y plane, and each first structure unit comprises a structure A, a structure B and a structure C which are arranged from bottom to top; similarly, an area II and an area III are formed, and a second structural unit in the area II comprises a structure C, a structure A and a structure B which are arranged from bottom to top; the third structure unit in the region III comprises a structure B, a structure C and a structure A which are arranged from bottom to top; the structure A, the structure B and the structure C are all regular hexagonal structures and have the same side length; a dislocation transmission line used for light wave transmission is arranged in the center of the primitive cell in the Z direction. Neutral state transmission can be realized only by adjusting a device structure and introducing defects without a magnetic field.

The invention belongs to the technical field of photonic crystals, and particularly relates to a photonic lattice capable of cutting boundaries in various modes and a method for generating a boundary state. In order to provide crystal lattices with a larger existence range, the evanescent coupling straight waveguides comprise a plurality of uniformly distributed crystal lattice points, the evanescent coupling straight waveguides are arranged on the crystal lattice points, every three crystal lattice points form a primitive cell, and the three crystal lattice points in each primitive cell form an equilateral triangle. The interfaces on the two sides of the evanescent coupling straight waveguide are arranged to be one or two of an alpha-zigzag shape, a beta-zigzag shape and a beam shape. According to the method, construction is simple, various boundaries can be cut, and two different types of boundary states are supported.

The invention discloses an acoustic topological acoustic fiber device based on a microstructure. The acoustic topological acoustic fiber device comprises a plurality of primitive cells arrayed in the Z direction. Each primitive cell is of a multi-layer honeycomb lattice structure and comprises an A-layer assembly, a middle-layer assembly, a B-layer assembly and a middle-layer assembly which are sequentially stacked from top to bottom. Pi phase difference delay exists between the A-layer assembly and the B-layer assembly. The middle layer assembly is constructed to be of an integral structure formed by connecting a plurality of coupling units. Seen from an X-Y plane, the primitive cell is constructed to be composed of a plurality of non-periodic structural units; rotation parameters are introduced into the structural units, so that the centers of the primitive cells have vortex centers, and the vortex centers are connected in the Z direction to form vortex lines. The acoustic topological acoustic fiber device disclosed by the invention can transmit in the center of the device in a defect immune manner without a magnetic field.

The invention discloses a device capable of localizing a surface acoustic wave center. The device comprises a device body and hard boundaries arranged on the upper surface and the lower surface of the device body. The device body comprises a plurality of primitive cells arrayed in the Z direction and an A-layer assembly arranged on the lower surface of the bottommost primitive cell. Each primitive cell comprises a B-A coupling layer assembly, a B-layer assembly, an A-B coupling layer assembly and an A-layer assembly which are sequentially stacked from bottom to top; pi phase difference delay exists between the A-layer assembly and the B-layer assembly. The primitive cell is constructed to be composed of a plurality of non-periodic structural units; the structural unit comprises a B-A coupling unit and a structure B which are arranged from bottom to top, the coupling strength of the A-B coupling unit and the coupling strength of the structure A are different, and the coupling strength of the A-B coupling unit and the coupling strength of the B-A coupling unit are different; rotation parameters are introduced into an X-Y plane in a three-dimensional space where the device is located, so that the primitive cell center has a vortex center, and the period of the primitive cell in the Z direction is of a limited size. Through the device, a zero-dimensional topological angular state can be formed, and surface acoustic waves are localized in the center of the top surface of the device.

The invention discloses a topological photonic crystal fiber. The topological photonic crystal fiber comprises a plurality of primitive cells periodically arrayed in the Z direction; each primitive cell is of a multi-layer honeycomb lattice structure and is provided with an upper layer assembly, a first middle layer assembly, a lower layer assembly and a second middle layer assembly which are stacked from top to bottom. The upper-layer assembly and the lower-layer assembly respectively comprise a plurality of aperiodic upper-layer and lower-layer structure units; the second intermediate layer assembly and the first intermediate layer assembly have the same structure and each comprise a plurality of periodic intermediate layer structure units; the primitive cells are further configured to form double vortex centers in an X-Y plane, and the vortex centers are connected in the Z direction to form double vortex lines. According to the invention, a central state with spin attribute and propagation track binding can be realized in a complete band gap of the topological photonic crystal fiber, and low-loss and robust transmission of electromagnetic waves along the center of the device can be realized without applying an external magnetic field.

The invention belongs to the technical field of multiferroic materials, and relates to a design method of a multiferroic body based on a vanadium-doped two-dimensional ferroelectric and the multiferroic body. Performing cell expansion on the single-layer NbOI2 primitive cell in different directions to obtain supercells with different sizes; the method comprises the following steps: doping supercells with different sizes by taking vanadium as a doping element to obtain a doping configuration of each supercell under different doping concentrations; taking the doping configuration with the lowest total energy of the ferromagnetic state and the antiferromagnetic state under each doping concentration as the ground state configuration of the doping concentration; calculating band gaps Eg of ground state configurations with different doping concentrations and spontaneous ferroelectric polarization intensity along a b axis, drawing a double-Y-axis curve graph by taking the doping concentrations as abscissas and the spontaneous ferroelectric polarization intensity and the band gaps Eg as ordinates, and dividing a multiferroic phase region and a magnetic semimetal phase region to obtain a doping concentration-physical property evolution phase diagram; and obtaining a corresponding doping concentration value range when the ground state configuration has a multiferroic phase with ferroelectricity and antiferromagnetism so as to design a multiferroic body.

Any primitive cells or blocks can be represented physically by a Barycenter compact model (or Barycenter model), and any black box model can also be physically represented by a Barycenter compact model physically. A boundary condition between blocks is formulated by the Barycenter compact model. Boundary condition problems between blocks can be limited within two levels only if using the Barycenter compact model.

The application discloses a single crystal growth method of Bi-O-Se-Cl four-component semiconductor material. The chemical formula of the Bi-O-Se-Cl four-component semiconductor material is Bi 10 O 12 SeCl4, each unit cell of the crystal contains 98 atoms, has a layered structure with two layers of [Bi 12 O 12 Se2Cl], two layers of [Bi6O 10 ] and four layers of [3Cl] alternately stacked along the c-axis. The growth method is as follows: bismuth powder and selenium powder are ground and mixed, and then a solid phase reaction is caused to obtain bismuth selenide; bismuth oxide, bismuth chloride and bismuth selenide are ground and mixed to obtain mixed powder 2, which is placed at the bottom of a quartz tube, vacuumized and sealed; the sealed quartz tube is horizontally placed in a two-zone furnace, and gas phase transportation is started; the hot end and the cold end of the two-zone furnace are respectively subjected to gradient heating and heat preservation, and after the end, the two-zone furnace is cooled, and thus Bi 10 O 12 SeCl4 crystals are obtained. The Bi 10 O 12 SeCl4 crystal has a complex layered structure and is a candidate material with intrinsic low thermal conductivity, and the growth method is simple and reliable.

The application belongs to the technical field of multiferroic materials, and relates to a design method of a multiferroic material based on a vanadium-doped two-dimensional ferroelectric body and the multiferroic material. Single-layer NbOI2 primitive cells are expanded in different directions to obtain supercells of different sizes. Vanadium is used as a doping element to dope the supercells of different sizes, and the doping configurations of each supercell under different doping concentrations are obtained. The doping configuration with the lowest total energy of the ferromagnetic state and the antiferromagnetic state under each doping concentration is used as the ground state configuration of the doping concentration. The band gap Eg and the spontaneous ferroelectric polarization intensity along the b-axis of the ground state configuration under different doping concentrations are calculated. A double-Y-axis curve graph is drawn with the doping concentration as the horizontal coordinate and the spontaneous ferroelectric polarization intensity and the band gap Eg as the vertical coordinate, and the multiferroic phase region and the magnetic semimetal phase region are divided. The doping concentration-physical property evolution phase diagram is obtained, so that the corresponding doping concentration value range of the ground state configuration with the multiferroic phase of ferroelectricity and antiferromagnetism is obtained to design the multiferroic material.

The application belongs to the field of antennas, and particularly relates to a valley directional antenna based on a gyromagnetic photonic crystal. The application adopts three dielectric columns and a gyromagnetic YIG column to construct a hexagonal unit cell, and provides a magnetic field through upper and lower magnet layers, so that the unit cell is divided into two arrays with angles theta being opposite numbers, and then the two arrays are adaptively closely arranged into an overall array antenna; an excitation source is arranged at the center of the functional layer. The valley directional antenna can be adjusted through parameters such as a magnetic field, an antenna structure and a frequency, so that the directivity of the antenna is regulated, and the antenna has multiple degrees of freedom adjustment characteristics. In the case that the antenna device has defects, the antenna can continue to work, and has high robustness. The antenna can be used for directional detection and anti-interference. There is no reflected signal, and due to the existence of topological protection, the wave in the waveguide can only be transmitted in one direction. Polarization and mode can be flexibly selected, so that polarization signals can be separated. The antenna has wide application, and can be used for directional detection, anti-interference, near-field detection and far-field detection.

The application belongs to the field of antennas, and particularly relates to a topological leaky-wave antenna based on a gyromagnetic photonic crystal. The application adopts a single gyromagnetic YIG column to construct a square unit cell, and provides a magnetic field by means of upper and lower magnet layers, the unit cell is adaptively closely arranged into an array antenna, and the boundary in each direction in a rated area is a perfect electric conductor boundary, and a gap array of a leaky-wave region is arranged on the boundary of an excitation source. The topological leaky-wave antenna can be adjusted by adjusting parameters such as a magnetic field, an antenna structure and a frequency, so that the leaky-wave scanning of the antenna is controlled, and the antenna has the characteristics of multi-degree-of-freedom adjustment. The antenna has the advantages of simple structure, good transverse emission effect, overcoming of the phenomenon of open stop band, overcoming of impedance matching, no reflected signal, one-way transmission of waves in a waveguide and the like. The problems of impedance matching and open stop band of the existing leaky-wave antenna are effectively solved.

The invention belongs to the technical field of photonic crystals, and particularly relates to an image boundary recognition and enhancement differential device based on topological singular points and a design method thereof. The differential device is a one-dimensional photonic crystal film, in particular to an optical film formed by periodically arranging and overlapping primitive cells which do not translate in the x direction and the y direction in the z direction. The photonic crystal structure has center inversion symmetry; the primitive cell is composed of three dielectric materials A, B and C, and the structure of the primitive cell is written as ABCBA; the incident image frequency is set to be singular point frequency, a singular point mode in the one-dimensional photonic crystal is excited, and boundary recognition and enhancement can be achieved at the topological singular point position. The structure and material parameters of the one-dimensional photonic crystal are adjusted, the topological singular point of the system is moved to an ultra-deep sub-wavelength region, and the effect can be achieved at the deep sub-wavelength. Through adjustment to different frequency points and angles, a wide-angle and ultra-wideband differential device can be realized. The device is simple in structure, small in absorption, high in anti-interference capability and high in integration level.

The invention provides a diamond indenter model construction method and device, molecular dynamics simulation equipment and a medium, and belongs to the technical field of molecular dynamics simulation computation.The method comprises the steps that basic macroscopic parameters of a diamond indenter model are set; the basic macroscopic parameters comprise the geometrical shape, the lattice type, the equivalent taper angle and the vertex coordinate of the diamond indenter model and the heights of different temperature control areas; determining a plurality of temperature control areas of the diamond indenter model based on the equivalent taper angle, the vertex coordinates and the heights of the different temperature control areas; determining primitive cells of the diamond indenter model and an initial basis vector of the primitive cells, and rotating the crystal orientation of the diamond indenter model to a target crystal orientation with the strongest non-deformability based on the initial basis vector; and filling the temperature control area with carbon atoms according to the primitive cell structure to obtain the target diamond indenter model. According to the method, the customized crystal orientation of the diamond indenter model is realized, and the problem of abnormal deformation of the diamond indenter model in the molecular dynamics simulation process is solved.

A technique generates a hierarchical three-dimensional structure or volume mesh and uses intelligent compaction using a Barycenter compact model. Any primitive cells or blocks can be represented physically by a Barycenter compact model (or Barycenter model), and any black box model can also be physically represented by a Barycenter compact model physically. A boundary condition between blocks is formulated by the Barycenter compact model. Boundary condition problems between blocks can be limited within two levels only if using the Barycenter compact model. A technique generates a hierarchical three-dimensional volume mesh and uses intelligent compaction using a Barycenter compact model.

The invention discloses a method for realizing directional excitation of a multi-dimensional coupling photon topological state, which is characterized in that three primitive cells PC1, PC2 and PC3 are combined into photonic crystals with different topological phases, the photonic crystals are of periodic structures, the periodic units of the photonic crystals are called primitive cells, and each primitive cell is composed of three circular ceramic dielectric cylinders; the three primitive cells are in 120-degree central rotational symmetry; each primitive cell has a specific center distance and a rotation angle, a splicing line of the two primitive cells PC1 and PC2 excites a one-dimensional topological boundary state mode, then a trapezoidal splicing body of the two primitive cells PC1 and PC3 excites a zero-dimensional topological corner state mode, and a final corner coupled cavity mode is formed by coupling of the two modes. According to the invention, a two-parameter tunable topological photonic crystal is realized, and in the crystal, various types of topological boundary states and angular states can be activated.

The application provides a topological phase discrimination method based on bulk region measurement. The method comprises the following steps: step 1, measuring S 21 parameters in a bulk region of a crystal with spatial symmetry, wherein the bulk region is a region except a boundary primitive cell; step 2, obtaining a field distribution with a phase from the S 21 parameters, performing Fourier transform on the field distribution, and then performing intrinsic state projection on the Fourier-transformed field distribution to obtain band structure information; and step 3, according to the band structure information, using a symmetry index theory to specifically discriminate the topological phase of the crystal. The method of the application uses the spatial symmetry of the topological structure, is based on bulk region measurement, realizes topological phase discrimination independent of boundary measurement, breaks through the limitation that traditional topological phase discrimination requires a full band gap and an interface state in a band gap, and has an immune feature to a defect state, and can adapt to a wider topological phase discrimination scene.

This application relates to the field of acoustics, and in particular to a method for realizing a three-dimensional phononic crystal structure, an acoustic supercell, and an acoustic device. The phononic crystal structure is composed of multiple stacked unit cells; each unit cell includes several resonant cavities and acoustic coupling channels connecting the resonant cavities; the layers are connected by interlayer acoustic coupling channels; the geometric parameters of the resonant cavities and acoustic coupling channels are configured to satisfy a tightly bound model with chiral symmetry, such that the phononic crystal structure forms nodal loops in three-dimensional momentum space and supports higher-order topological hinge states at the rigid boundary edges of the phononic crystal structure. This invention can achieve stable higher-order topological hinge states while maintaining the characteristics of nodal loops, and has the advantages of simple structure and ease of fabrication.

The invention relates to a filled skutterudite crystal and a preparation method thereof, and belongs to the technical field of skutterudite materials. The chemical formula of the crystal is TexRh4Sb12, wherein x ranges from 0.1 to 1; the crystal is a cubic system, the space group is Im-3 (NO.204), the lattice constant alpha = beta = gamma = 90 degrees, and the theoretical density of the primitive cell volume of the crystal is 8.1-8.5 g / cm < 3 >. The crystal is subjected to semiconductor-insulator conversion along with temperature reduction, has sensitivity and relatively high resistivity at low temperature, is a potential energy material, and has obvious application value in the fields of thermoelectric conversion, temperature sensing and the like.

A technique generates a hierarchical three-dimensional structure or volume mesh and uses intelligent compaction using a Barycenter compact model. Any primitive cells or blocks can be represented physically by a Barycenter compact model (or Barycenter model), and any black box model can also be physically represented by a Barycenter compact model physically. A boundary condition between blocks is formulated by the Barycenter compact model. Boundary condition problems between blocks can be limited within two levels only if using the Barycenter compact model. A technique generates a hierarchical three-dimensional volume mesh and uses intelligent compaction using a Barycenter compact model.

The application discloses a kind of on-chip topological state modulators based on Schottky diode, including electromagnetic wave input area, metal film topological structure transmission area, control signal feed-in area, electromagnetic wave output area, the metal film topological structure transmission area is by several two different cells and is arranged according to hexagonal lattice array, and Schottky diode is installed at cell wall boundary, the distribution period of Schottky diode is same with cell lattice constant, and the on-off state of Schottky diode is controlled by the voltage of control signal feed-in area.The application utilizes metal film to construct honeycomb lattice topological structure, breaks space inversion symmetry in topological structure by using structure perturbation to open topological band gap, and by installing Schottky diode at wall boundary, high switch ratio topological boundary state single-mode transmission control can be realized by adjusting and controlling band gap dispersion mode distribution.