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85 results about "Source plane" patented technology

High-precision near-field acoustic holography algorithm adopting weighted iteration equivalent source method

InactiveCN105181121APrevent leakageEquivalent Source Strength AccurateSubsonic/sonic/ultrasonic wave measurementEquivalent source methodSource plane
The invention discloses a high-precision near-field acoustic holography algorithm adopting a weighted iteration equivalent source method, which is characterized in that a holographic plane H is arranged in a sound source near-field radiation area, and sound pressure PH on the holographic plane H is measured; an equivalent source plane Se is arranged at the side, which is away from the holographic plane H, of an object reconstruction plane T, and equivalent sources are arranged on the equivalent source plane Se; a relation between the sound pressure PH and each equivalent source is established by using a sound pressure transfer matrix between the equivalent source and the holographic plane H; and the source intensity Q of each equivalent source is solved by adopting a new iterative regularization algorithm with a posteriori weighted norm constraint penalty term, and then sound field data on the object reconstruction plane T is calculated by using the solved source intensity Q and the transfer matrix between the equivalent source and the object reconstruction plane T. According to the invention, the source intensity of each equivalent source is precisely solved by using the new iterative regularization algorithm with the posteriori weighted norm constraint penalty term, thereby avoiding source intensity energy leakage caused by a 2-norm penalty term in the Tikhonov regularization process. Compared with conventional equivalent source based near-field acoustic holography, a calculation result acquired by the method disclosed by the invention is more accurate.
Owner:HEFEI UNIV OF TECH

Method for generating vortex light beam by use of calculation hologram

The invention discloses a method for generating a vortex light beam by use of a calculation hologram. The steps comprise: (1), utilizing a monocyclic Laguerre-Gaussian (LG) vortex light beam in a source plane (z=0m) coordinate system; (2), performing conjugate symmetrical extension on the complex amplitude of the vortex light beam, and obtaining symmetrical vortex light beam complex amplitude distribution; (3), performing Fourier transformation on the conjugate symmetrical vortex light beam complex amplitude distribution to obtain two-dimensional discrete real function distribution, performing DC component inhibition on real functions, and coding to form the vortex light beam calculation hologram; (4), performing Fourier inverse transformation on the calculation hologram, obtaining the light intensity distribution and the phase distribution of the vortex light beam, and taking the left half portions of the light intensity distribution and the phase distribution as the vortex light beam for digital reconstruction; and (5), loading the vortex light beam calculation hologram on a spatial light modulator, modulating incident laser and reconstructing the vortex light beam in a photoelectric mode. The method employs a conjugate symmetrical extension Fourier calculation holographic algorithm, the algorithm is rapid and simple, the calculation efficiency is high, and sidelobe-free high-quality vortex light beams can be generated.
Owner:SHANGHAI UNIV

Method for sound field separation by double plane vibration speed measurement and equivalent source method

The invention provides a method for sound field separation by double plane vibration speed measurement and equivalent source method, which is characterized in that a measurement plane S1 and an auxiliary measurement plane S2 parallel therewith and Delta h therefrom are provided in the measured sound field; normal direction particle vibration speed on the two planes are measured; two imaginary source planes S1* and S2* are provided, and equivalent source are distributed on the imaginary source planes; transfer relationship between the equivalent source and normal direction particle vibration speed on two measurement planes are established; strength of each equivalent source on the imaginary source planes S1* and S2* are determined according to the transfer relationship; sound pressure and normal direction particle vibration speed radiated by sound sources on both sides of the two measurement planes are separated according to strength of equivalent source on two imaginary source plane. The invention adopts equivalent source method as the sound source separation algorithm, which has great computation stability, high computation accuracy, and simple implementation; normal direction vibration speed on two measurement planes are used as input for the separation, therefore vibration speed of the separated normal direction particle has high accuracy. The method is widely applicable near-field acoustic holographic measurement under internal sound field or noise environment, material reflection coefficient measurement, scattering sound field separation.
Owner:HEFEI UNIV OF TECH

Complex shape sound source surface instantaneous acceleration reconstruction method

The invention discloses a complex shape sound source surface instantaneous acceleration reconstruction method. The complex shape sound source is internally and externally provided with a hologram plane and an equivalent source plane which are conformal with the sound source, and time domain sound pressure signals on the hologram plane are acquired; according to a principle of a time domain equivalent source method, a time domain equivalent source strength is used as a medium to build the relationship between the time domain sound pressure on the hologram plane and a time domain normal acceleration of the sound source surface; the time domain sound pressure on the hologram plane and a known Green function are then used to solve all equivalent source strengths at all moments through an iterative inversion process; and the solved equivalent source strengths are finally used to calculate the normal acceleration of the sound source surface at each moment. The invention provides a non-contact instantaneous acceleration acquisition method, and influences on a sound source itself vibration mode by acceleration sensor additional mass can be avoided. The method has an ability of processing any shape sound source and can be used for complex shape structure surface instantaneous acceleration measurement in practical engineering.
Owner:ANHUI UNIVERSITY

Circuit board having multicycle planar electromagnetic band gap structure

InactiveCN102316670ANo increase in construction areaCancel noisePrinted circuit detailsSource planeBroadband
The invention discloses a circuit board having a multicycle planar electromagnetic band gap structure. According to the invention, a problem ofnarrow stop band width of a current circuit board with a planar electromagnetic band gap is solved. The circuit board provided in the invention is composed of a power source plane (1), a ground plane (2), and a dielectric layer (3). The power source plane (1) comprises a plurality of minor cycle planar electromagnetic band gap units (101), a plurality of major cycle planar electromagnetic band gap units (102) and a plurality of cascading bridging line connections (103); the two planar electromagnetic band gap units (101) and (102) are respectively at a left side and a right side of the power source plane and are arranged in a square matrix mode; besides, the two planar electromagnetic band gap units are connected by the cascading bridging line connections (103) to construct a multicycle power source planar structure. According to the invention, when an inhibition depth is -30 dB, a stop band range is from 0.7 GHz to 8.4 GHz and a stop band width is 7.7 GHz; compared with a circuit board having a single cycle planar electromagnetic band gap unit, the circuit board provided in the invention has an obviously broadened band gap width, so that synchronous switch noise can be effectively inhibited; therefore, the circuit board provided in the invention can be applied to a high speed circuit and a broadband device.
Owner:XIDIAN UNIV

Variable-step-size obscuration forecasting method

The invention discloses a variable-step-size obscuration forecasting method. The variable-step-size obscuration forecasting method comprises the steps of: firstly, defining a satellite-target source coordinate system and establishing a conversion matrix corresponding to a WGS-84 coordinate system; then establishing a criterion of obscuration events of a satellite in the satellite-target source coordinate system; if the criterion is satisfied, further judging whether a vector of a connecting line between the satellite and a target source is within an observable range of a satellite obscuration antenna; if so, considering that an obscuration event occurs, and further performing effective forecasting on the obscuration event. The obscuration generation process is converted into a geometrical problem that a fixed-point rotating ray cuts the circumference within the satellite-target source plane by adopting a coordination conversion idea, so that the physic principle of the generation of the obscuration event is revealed substantially; the variable-step-size obscuration forecasting method is a variable-step-size obscuration forecasting algorithm which can efficiently improve the calculation efficiency; through the combination with the installation of the satellite obscuration antenna, the variable-step-size obscuration forecasting method is suitable for the practical project application and is particularly suitable for forecasting the sun or the GPS obscuration event for a long time.
Owner:AEROSPACE DONGFANGHONG SATELLITE

Electromagnetic band gap structure for achieving ultra-wideband suppression of synchronous switching noise

The invention discloses an electromagnetic band gap structure for achieving ultra-wideband suppression of synchronous switching noise. The electromagnetic band gap structure is characterized in that arectangular notch is etched on each side of a power plane, and a microstrip line is led out from the middle point of the bottom of the notch; the microstrip line surrounds the power plane to the tailend of the next side in a counterclockwise direction, and the part of the microstrip line positioned at the next side surrounds the part of the microstrip line positioned at the side, which is led out from the rectangular notch at the side; the microstrip line is connected with the microstrip line of the adjacent structural unit to form an S shape; the central area of the power plane is hollow, and a square plane plate is inlaid in the central area; a rectangular notch is etched in the center of each of four sides of the square plane plate, and a microstrip line is led out from the middle point of the bottom of the rectangular notch and connected with the power plane. The electromagnetic band gap structure better reduces the lower cut-off frequency of noise suppression and effectively enlarges the bandwidth range of noise suppression, thereby achieving the ultra-wideband suppression of the synchronous switching noise between the power plane and a ground plane.
Owner:HANGZHOU DIANZI UNIV

Anti-electromagnetic-interference circuit board

The invention relates to the field of circuit boards, in particular to an anti-electromagnetic-interference circuit board. The anti-electromagnetic-interference circuit board comprises a circuit board body provided with an inductor. The area, where the inductor is installed, of the circuit board body is provided with a mechanical hole and / or an arrangement-forbidding area. The power source plane, the ground plane and interconnecting wires in the circuit board body all keep away from the mechanical hole and / or the arrangement-forbidding area. The inductor is a main source of the electromagnetic interference problem in the circuit board body. According to the anti-electromagnetic-interference circuit board, the area, where the inductor is installed, of the circuit board body is provided with the mechanical hole and / or the arrangement-forbidding area, the power source plane and the ground plane in the circuit board body and the interconnecting wires among various parts in the circuit board body all keep away from the mechanical hole and / or the arrangement-forbidding area, therefore, mutual interference between the electromagnetic field generated by the inductor and the electromagnetic fields generated by the areas, intersected with the area where the inductor is installed, of the power source plane, the ground plane and / or the interconnecting wires is avoided, the electromagnetic interference in the circuit board body can be effectively reduced, and the signal quality of the power source plane, the ground plane and the interconnecting wires among the various parts in the circuit board body is improved.
Owner:GUANGDONG VTRON TECH CO LTD
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