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105 results about "Bi-isotropic material" patented technology

In physics, engineering and materials science, bi-isotropic materials have the special optical property that they can rotate the polarization of light in either refraction or transmission. This does not mean all materials with twist effect fall in the bi-isotropic class. The twist effect of the class of bi-isotropic materials is caused by the chirality and non-reciprocity of the structure of the media, in which the electric and magnetic field of an electromagnetic wave (or simply, light) interact in an unusual way.

System and method converting the polarization state of an optical beam into an inhomogeneously polarized state

A system for converting the polarization state of an optical beam which propagates along a path from an initial polarization state into an inhomogeneous polarization state in accordance with embodiments of the present invention includes a first anisotropic material positioned adjacent to the first isotropic material in a substantially transverse manner relative to the path of the optical beam, wherein the first anisotropic material has a first alignment axis that produces one of a radially, azimuthally, and counter-rotationally polarized optical beam when substantially aligned with respect to a polarization axis of the optical beam. The system may further include a second isotropic material and a second anisotropic material positioned adjacent to the second isotropic material in a substantially transverse manner relative to the path of the optical beam, wherein the second isotropic material and second anisotropic material are positioned downstream of the first isotropic material and first anisotropic material along the path of the optical beam, and wherein the second anisotropic material has a second alignment axis that produces one of a radially, azimuthally, and counter-rotationally polarized optical beam when substantially aligned with respect to the polarization axis of the optical beam. In addition, the present invention relates to an optical beam having an inhomogeneous polarization state in which the polarization rotates in a continuous and counterclockwise manner while traversing a circular path around the beam axis in a clockwise direction.
Owner:UNIVERSITY OF ROCHESTER

Method for detecting isotropic material surface Young modulus by using surface acoustic wave technology

A method for detecting isotropic material surface Young modulus by using surface acoustic wave technology. The method is as below: exciting broadband surface acoustic wave in an isotropic specimen surface to obtain a dispersion curve on a surface acoustic wave propagation direction; fitting the actual phase velocity data to obtain a closest truth-value phase velocity and a phase velocity fluctuation section; establishing a Cartesian coordinate geometry model to obtain a surface wave basic propagation equation containing unknown medium Young modulus, Poisson ratio, direction cosine of the propagation direction, amplitude attenuation coefficient given according to experience value, wave number and wave velocity; calculating assumption corresponding relation between wave velocity and wave number in the Cartesian coordinate geometry model and simultaneous theoretical relationship, to obtain mutual relationship of velocity, frequency and Young modulus under ideal conditions; and conducting reverse calculation to obtain the Young modulus in medium according to the mutual relationship of velocity, frequency and Young modulus under ideal conditions and the dispersion curve under actual conditions. The invention realizes effective measurement of isotropic material surface young modulus.
Owner:TIANJIN UNIV

Fiber reinforced ceramic matrix composite microstructure accurate modeling and modulus calculation method

The invention discloses a fiber reinforced ceramic matrix composite microstructure accurate modeling and modulus calculation method. The method comprises the following steps S1, establishing a fiber filament scale finite element model; S2, establishing a finite element model of cellosilk scale microcracks and pore distribution; S3, calculating a unit stiffness matrix of each unit; S4, calculatingaverage stress and average strain of all units of the fiber filament scale finite element model; S5, establishing a fiber bundle scale woven body model; S6, establishing a finite element model of poredistribution in the fiber bundle scale braided body; S7, calculating a unit stiffness matrix in each unit; And S8, calculating average stress and average strain of all units of the fiber bundle scalewoven body model. According to the method, the microstructure characteristics, the microcracks and the pores of the woven body with the fiber size and the fiber bundle size are comprehensively considered, the transverse isotropic material characteristics of the fiber bundles at different weaving positions are effectively set, and a more accurate macroscopic effective modulus value can be obtainedthrough calculation.
Owner:SOUTHWEST JIAOTONG UNIV

Versatile method and system for single mode VCSELs

A system and method for providing a single mode VCSEL (vertical cavity surface emitting laser) component (100) is disclosed, comprising a semiconductor substrate (102) having a lower surface and an upper surface, a bottom electrical contact (104) disposed along the lower surface of the substrate, a lower mirror (106) formed of n-type material and disposed upon the upper surface of the substrate, an active region (108) having a plurality of quantum wells disposed upon the lower mirror portion, an upper mirror (110) formed from isotropic material and disposed upon the active region, an equipotential layer (112) disposed upon the upper mirror portion, a first upper electrical contact (120) disposed upon the equipotential layer, a second upper electrical contact (122) disposed upon the equipotential layer at a particular distance (124) from the first upper electrical contact, a first isolation region (126) disposed beneath the first upper contact and traversing the equipotential layer, the upper mirror, the active region, and the lower mirror, a second isolation region (128) disposed beneath the second upper contact and traversing the equipotential layer, the upper mirror, the active region, and the lower mirror, and an insulating layer (114, 116) interposed between the upper mirror and the equipotential layer and adapted to form therebetween an aperture (118) of smaller dimension than the particular distance between the first and second upper contacts.
Owner:II VI DELAWARE INC

Automatic generating method of three-dimensional woven composite hexahedron finite element model

ActiveCN107330148AFast establishment of finite element model functionRemoving Barriers to Mesostructural CharacterizationDesign optimisation/simulationSpecial data processing applicationsElement modelFiber bundle
The invention discloses an automatic generating method of a three-dimensional woven composite hexahedron finite element model. The method includes the following steps that a space trajectory in the fiber bundle center weaving process is calculated, and position coordinates of the center of each fiber bundle are obtained; position coordinates of space trajectories of center points of the fiber bundles are read, in other words, the position coordinates of each tightened fiber bundle are read, and geometric creation, direction grouping and hexahedron meshing are carried out. By means of the method, the rapid finite element model establishment function of a complex geometric structure three-dimensional woven composite can be achieved only by inputting multiple simple macroparameters. In combination with the geometric structure and finite element modeling, grouping is carried out according to fiber bundle center direction vectors, material spindle direction setting of transverse isotropy materials of the fiber bundles is convenient, the change of internal zone, surface zone and corner zone fiber bundle sections is considered, and transverse isotropy finite element model establishment of the large-size three-dimensional woven composite can be achieved in reality from being manually feasible theoretically.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Acoustic emission source positioning method suitable for three-dimensional structure

The invention relates to an acoustic emission source positioning method suitable for a three-dimensional structure, belongs to the technical field of sound source positioning, and the position of theacoustic emission source is positioned through the time difference information and the space information of the right-angled tetrahedron type sensor array. The method comprises the following steps: establishing a three-dimensional sound emission source positioning sensor array, recording and storing sound wave signals from a sound source received by each sensor, analyzing a sound wave signal graphto obtain a required time difference, and determining the position of the sound source according to the time difference. The method is not only suitable for isotropic materials, but also can be wellsuitable for anisotropic materials; only eight ultrasonic sensors are needed, so that the cost of the continuous monitoring structure can be greatly reduced; any iterative algorithm is not needed, andthe positioning precision and speed are effectively improved. The invention provides a new method for sound source localization in acoustic emission detection, guarantees the safety of the structureby discovering damage and potential threats in time, and has a good application prospect in the fields of spaceflight and navigation, civil engineering, large and small machinery and the like.
Owner:JILIN UNIV

Device and method for measuring shearing property of transverse isotropic material

The invention relates to a device and a method for measuring shearing property of a transverse isotropic material. The device comprises a thin-wall tubular test piece, a fixed outer tube, a rotary inner tube, an upper positioning ring, a lower positioning ring, structure adhesive, an upper connecting disc, a lower connecting disc, a flange and a torque sensor. The transverse isotropic material is processed into the thin-wall tubular test piece, the axial direction is a direction I, a direction II and a direction III (transverse direction) are mutually perpendicular to each other in a cross section, and the mechanical properties of the material are identical. The rotary inner tube and the fixed outer tube are respectively bonded to the inner wall and the outer wall of the test piece, the outer tube is fixed, and a torsion torque is applied to the inner tube, so that the test piece only generates a shearing force in the thin-wall annular cross section. The shearing stress-strain curve of the test piece in the directions (transverse) II and III can be acquired by virtue of the torque of the outer tube, a torsion angle of the inner pipe and the outer wall surface of the inner tube, so that the shearing modulus and shearing strength of the test piece in the transverse isotropic direction can be obtained. The relative twisting of the inner wall and the outer wall of the thin-wall tube is ingeniously utilized, so that the shearing force is only generated in the transverse isotropic direction of the material, the parameter is intuitive and convenient to measure, and the test data is accurate.
Owner:INST OF ENGINEERING THERMOPHYSICS - CHINESE ACAD OF SCI
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