56results about How to "Reduce interface reflection" patented technology

The invention discloses a quasi-spatial domain elastic wave equation-based finite difference calculation method, belongs to the field of seismic exploration, and mainly mains at converting a conventional elastic wave equation into a quasi-spatial domain elastic wave equation so as to convert equally spaced distance grid step lengths of spatial domains into non-equally spaced propagation time steplengths so that people can accurately calculate propagation times at two sides of speed interfaces on the basis of strictly defining speed models. On the basis, the equation and a 2N (N is a positiveinteger)-order precision finite different expression of a completely matched layer boundary condition are given, so that finite difference wave field prolongation of seismic waves in a reverse time migration process can be realized. According to the method, the problem that a speed interface, in a reverse time migration section, of the conventional elastic wave equation is distorted can be well solved; and moreover, through carrying out wave field prolongation on the basis of a quasi-spatial domain elastic wave equation, interface false scattering and inter-layer reflection waves can be obviously weakened, so that the migration imaging quality is further improved.

A device and method for analyzing characteristics of a fluid. The device is a bolus arranged to remain within the fluid for the analysis. The bolus includes a sensor module, a fluid analysis module, a fluid pumping module and a control and data transmission module. The sensor module includes a transducer element to generate acoustic signals and convert acoustic signals. The information derived from generating and receiving acoustic signals is used to obtain information about constituents and conditions of the fluid. That information may be transferred to a near or remote location for analysis. The device and analysis method are suitable for evaluating the health of animals. The device may be used in a telemedicine environment at an animal health facility. It may also be uploaded to a database for use in the analysis of a group of sources of fluid, such as a herd of cows.

The invention relates to a finite difference calculation method based on the quasi-spatial domain acoustic wave equation and belongs to the field of seismic exploration. The main idea of the method isto transform a conventional acoustic wave equation into a quasi-spatial domain acoustic wave equation so that the equally spaced 'distance' grid length steps in the spatial domain is transformed intonon-equally spaced 'propagation time' length steps. Thus, a user can accurately calculate the 'propagation time' on both sides of a velocity interface based on a strictly defined velocity model. Then, the equation of a 2N-order (N is a positive integer) precision finite difference expression for its perfectly matched layer boundary condition is given based on this. Accordingly, the finite difference wavefield extension of seismic waves in the process of reverse time migration can be realized. The method can well solve the problem of the shape distortion of the velocity interface in the reverse-time migration profile of a conventional acoustic wave equation. In addition, the wave field extension based on the quasi-spatial domain acoustic wave equation can significantly weaken the interfacepseudo-scattering and the inter-layer reflection wave so as to further improves the quality of offset imaging.

Provided is a noise reduction green belt constructed with photonic crystal, the green belt is constructed with a certain amount of trees planted according to a special array approach, and the array constitutes a definite photonic crystal structure. In the noise reduction green belt constructed with photonic crystal, the diffuser (1) is of green grass and trees, and the base (2) is air. The special array is a rectangular shape structure, and arranged in parallel by order using 2n rows of trees, the n rows of mutually parallel trees form a group, an empty row space of trees is left between two groups in n rows of trees, and a rectangular middle cavity (3) is formed, wherein n is 2-5. The said certain amount is 32-180. Crystal lattice coefficients are counted as coefficients of two type, three type, four type, and five type. The hollow cavity design effectively captures incident noise, reduces the out leakage of noise, thus strengthens sound insulation and noise reduction ability; the invention adopts grass and trees as the diffuser, to guarantee the function of green standardization and beautification, air purification, environment protection and energy saving; using air as the base can guarantee the smooth circulation of the air.

The invention relates to a polarization-independent type photo-isolator. The polarization-independent type photo-isolator comprises a first crystal wedge angle piece and a second crystal wedge angle piece. The first crystal wedge angle piece and the second crystal wedge angle piece are fixed to the two ends of a magneto-optical crystal device respectively in an optical cement mode. During forward transmission, the first crystal wedge angle piece divides parallel light from a first optical collimator into light o and light e. The magneto-optical crystal device rotates the polarization faces of the light o and the light e in the identical direction by 45 degrees, so that the light o and the light e are transmitted to the second crystal wedge angle piece, and the second crystal wedge angle piece refracts the light o and the light e to form two beams of parallel light; during reverse transmission, the second crystal wedge angle piece divides parallel light from the second optical collimator into light o and light e, and at the moment, a first included angle is formed between the light o and the light e. The magneto-optical crystal device rotates the polarization face of the light o and the light e in the identical direction and then transmits the light to the first crystal wedge angle piece, the first crystal wedge angle piece refracts the light o and the light e to form light e and light o, and at the moment, a second included angle is formed between the light e and the light o, wherein the second included angle is larger than the first included angle. The insertion loss of the polarization-independent type photo-isolator can be lowered.

The invention provides a head mounted display. The head-mounted display comprises two display units which are respectively arranged in front of two eyes of a user. Each display unit comprises a display device, a Fresnel lens and a plurality of moth eye structures, the Fresnel lens is disposed between the display device and one eye of the user, and the plurality of moth eye structures are located on at least one surface between the display device and one of the eyes of the user.

The invention provides a light collimator and a manufacturing method thereof. The light collimator comprises a light transmitting substrate and a plurality of light absorbing patterns, wherein two opposite surfaces of the light transmitting substrate are respectively provided with a plurality of depressions which are arranged at intervals, and the depressions on the two surfaces are mutually aligned; and the light absorbing patterns are arranged in the depressions. The light collimator and the manufacturing method thereof provided by the invention can enable the light absorbing patterns on thetwo opposite surfaces of the light transmitting substrate to be mutually aligned, reduce the interface reflection and improve a problem of scratches.