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240results about How to "Filter noise" patented technology

Self-excited oscillation type high power LED constant-current driving circuit

The invention provides a self-oscillation type high power LED constant-current drive circuit with low cost, high reliability and stability and high drive efficiency, the circuit comprises a rectifier and filter circuit, a switching circuit, a steady voltage constant current output circuit, a transformer, a self-oscillation type pulse width modulation signals generating circuit and a current feedback obstruction circuit, wherein the rectifier and filter circuit accesses commercial power into rectification, changes the commercial power into direct current, and then outputs commercial power to the switching circuit to switch in a self-oscillation type with high frequency, then high frequency voltage of the steady voltage constant current output circuit is transformed into direct voltage through the transformer to drive the LED, simultaneously sampling current signals produces jam signals through the current feedback obstruction circuit to control the switching circuit to work, the circuit does not adopt any driving chips and only uses fewer common individual devices to form a self-oscillation type structure to drive the switching circuit and to combine current feedbacks, which realizes constant current driving of the high power LED.
Owner:NANTONG LIWANG MACHINE TOOL +1

Underwater image enhancement method in combination with bilateral filtering and Retinex

The invention discloses an underwater image enhancement method in combination with bilateral filtering and Retinex. The method comprises the steps of converting an RGB color space of an input image toan HSV color space; for a brightness component, filtering image noises in combination with the bilateral filtering, and separating out a reflective component and an irradiation component based on Gaussian center surrounding multi-scale Retinex for the denoised brightness component; for the separated irradiation component, adjusting illumination by adopting gamma correction to obtain a new irradiation component; realizing fusion enhancement of the irradiation component and the reflective component based on a Retinex theory, thereby obtaining a brightness component after non-uniform illumination correction; recombining the enhanced brightness component with a hue component and a saturation component, and converting the HSV color space to the RGB color space; calculating grayscale value ratios of red and green channels to a blue channel, and remapping the grayscale values of the three channels; and finally performing histogram equalization on the R, G and B channels of the image to realize image contrast enhancement. According to the method, the blue and green color deviation of the underwater image is effectively eliminated, so that the image contrast is improved; and the partial image noises are filtered, so that the signal-noise ratio of the image is increased.
Owner:TIANJIN UNIV

Method and device of pavement identification on the basis of laser-point cloud

The present invention discloses a method and device of pavement identification on the basis of a laser-point cloud. The method provided by the invention comprises: identifying candidate pavement point clouds according to the laser-point cloud collected by a laser sensor; constructing a rectangular coordinate system grid, clustering a candidate pavement point cloud projected to the rectangular coordinate system grid, and obtaining a credible pavement point cloud; and constructing a pavement model according to the credible pavement point cloud and the driving direction of a mobile carrier provided with the laser sensor. Through the technical scheme provided by the embodiment of the invention, a candidate pavement point cloud is identified according to the laser-point cloud collected by a laser sensor, a credible pavement point cloud is obtained by clustering the candidate pavement point cloud projected to the rectangular coordinate system grid, and finally a pavement model is constructed according to the credible pavement point cloud and the driving direction of a mobile carrier provided with the laser sensor, therefore the noise in a pavement laser-point cloud is effectively filtered and the accuracy of the construction of the pavement model is improved.
Owner:BAIDU ONLINE NETWORK TECH (BEIJIBG) CO LTD

Method and system for testing dynamic stiffness

The invention relates to the field of traffic rails and specifically relates to a method and a system for testing dynamic stiffness. The method for testing the dynamic stiffness includes that a force in a preset frequency range is applied to a rail in preset time to enable the rail to produce vibration; force signals and vibratory acceleration signals are real-timely acquired according to a preset sampling frequency; data of the force F, time corresponding to the force F, data of an acceleration a and time corresponding to the acceleration a are recorded according to preset time intervals, the acquired force signals and the acquired acceleration signals; a corresponding relation of a displacement X and the frequency f is obtained according to the corresponding relation of the data of the acceleration a and the time corresponding to the acceleration a; the corresponding relation of the displacement X and the time t is obtained; and the corresponding relation of the dynamic stiffness Z and the frequency f is obtained according to the corresponding relations and the corresponding relation of the dynamic stiffness, the displacement and the force, and namely, wide frequency dynamic stiffness is obtained. By means of the method and the system for testing the dynamic stiffness, the wide frequency dynamic stiffness of the rail can be tested.
Owner:SOUTHWEST JIAOTONG UNIV

Fundus image vascular segmentation method based on phase congruency

The invention discloses a fundus image blood vessel segmentation method based on phase congruency and mainly overcomes the defect that a traditional method can not be used to accurately segment blood vessels in fundus images. The fundus image vascular segmentation method base on the phase congruency can be simultaneously used to segment small blood vessels of most tips. The method comprises the steps: (1) extracting green channels of the fundus images, (2) enhancing the contrast ratio of the images through contrast limited adaptive histogram equalization (CLAHE), (3) filtering the fundus images through the anisotropic coupled diffusion equation, (4) segmenting the blood vessels of the fundus images filtered or not filtered through the anisotropic coupled diffusion equation in a phase congruency algorithm, (5) multiplying pixel-levels of results of vessels, of two fundus images, segmented based on the phase congruency algorithm, (6) processing the images in a binaryzation mode through the iterative threshold segmentation method, (7) optimizing the images in the mathematical morphology method. The fundus image vascular segmentation method has significant application values in fields of three-dimensional splicing of the fundus images and judging existence of diabetes mellitus and severity of diabetes mellitus.
Owner:TIANJIN POLYTECHNIC UNIV

Method for detecting cable connection of intelligent antenna outdoor unit

InactiveCN101154977APrecise positioning of the connection sequenceEasy to implementSpatial transmit diversityComputation complexityCoaxial cable
The present invention discloses a method for detecting the cable connecting of the outdoor unit of the intelligent antenna, which settles the problem that the connecting sequence can not be detected when the intelligent antenna array is connected with the front unit of the outdoor radio frequency by a radio frequency coaxial cable in the TD-SCDMA communication system. The invention presents a method for confirming the connecting sequence of the corresponding cable according to the estimated data of the communication channel, changing the complexor sequence in the antenna array direction, searching the maximum value of the energy in the air space, and the antennae array direction complexor sequence which corresponds with the maximum value. The present invention effectively settles the problem of detecting the connecting sequence of the of the radio frequency cable in the realizing of the intelligent antenna project; the detecting sequence of the present cable can be accurately detected while the upgoing communication channel is adopted to process the data according to the criterion that the space detecting receiving power is maximum traversing all the cables at the condition that the calculating difficulty is effectively controlled; the smooth arithmetic is adapted for the originality, the noise and disturbance are sieved and the correctness of the detecting arithmetic is increased.
Owner:ZTE CORP

System and method for synchronously acquiring load and response signals of machine tool vibration test

The invention relates to a system and a method for synchronously acquiring load and response signals of a machine tool vibration test. The system comprises four parts, namely an excitation subsystem, a response signal acquisition subsystem, a data acquisition front end and a data processor, wherein the excitation subsystem comprises a power amplifier, a vibration exciter and a vibration exciting rod; the response signal acquisition subsystem comprises a force sensor, multiple acceleration sensors and multiple charge amplifiers; the input end of the data acquisition front end is connected with the response signal acquisition subsystem; one output end of the data acquisition front end is connected with the excitation subsystem, and the other output end of the data acquisition front end is connected with the input end of the data processor; and the data processor prestores a program for performing data processing on the load and response signals. The test system can be used for avoiding measurement errors caused by signal delay, filtering out errors in acceleration signals, and accurately analyzing the dynamic vibration response of each part and the complete machine of a machine tool, and has the advantages that the test is accurate, the operation is simple and the like.
Owner:TSINGHUA UNIV
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