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1257 results about "Projection direction" patented technology

System and method for phase-contrast imaging by use of X-ray gratings

ActiveCN101532969AReduce production difficulty requirementsLower application thresholdComputerised tomographsTomographyGratingRefractive index
The application relates to a system and a method for the phase-contrast imaging by use of X-ray gratings. The system comprises an X-ray device, a first absorption grating, a second absorption grating, a detection unit, a data processing unit and an imaging unit, wherein the X-ray device transmits an X-ray bundle to a detected object; the first and second absorption gratings are positioned in the direction of the X-ray bundle; the X-ray refracted by the detected object forms an X-ray signal with variable intensity through the first absorption grating and/or the second absorption grating; the detection unit receives and converts the X-ray with variable intensity into an electrical signal; the data processing unit processes and extracts refraction-angle information in the electrical signal, and utilizes the refraction-angle information to figure out pixel information; and the imaging unit constructs images of the object. In addition, the system and the method can also realize CT imaging by using a rotating structure to rotate the object so as to obtain refraction angles in a plurality of projection directions and the corresponding images, and use CT reconstruction algorithm to figureout refraction-index fault images of the detected object. According to the invention, the phase-contrast imaging of approximate decimeter-magnitude viewing fields under incoherent conditions can be realized by use of common X-ray machines or multi-seam collimator such as source gratings, as well as two absorption gratings.
Owner:NUCTECH CO LTD +1

Method and device for detecting polarization extinction ratio of optical polarizer

The invention provides a method and device for detecting a polarization extinction ratio of an optical polarizer. The detection method comprises the following steps of: making linear polarized light incident along a principal axis of an optical polarizer to be detected, and obtaining two light signals on two orthogonal optical axes at an outgoing end due to polarization crosstalk; interfering and carrying out photoelectric conversion and data acquisition on interfering light signals to obtain one group of discrete voltage signal values reflecting the interfering light intensity signals; and calculating coupling intensity h at each coupling spot based on a formula (1), and calculating an extinction ratio of the optical polarizer to be detected based on a formula (2). The device sequentially comprises a light source, an isolator module, a polarization module, the optical polarizer to be detected, a projection direction regulating module, an interferometer module, a data acquisition module and a central processor module. The invention has the advantage that the coupling intensity of the coupling spots is detected to induce the polarization extinction ratio, so that the measurement result is accurate. The invention is suitable for various optical polarizers, such as polarization maintaining fibers, polarization maintaining fiber couplers, polarizers and the like and has certain universality.
Owner:TIANJIN UNIV +1

Method for actively tracking and monitoring infants and realization system thereof

The invention discloses a method for actively tracking and monitoring infants, which firstly detects movement regions; then extracts smaller candidate regions including human face and hand or the like, and then detecting human faces. The method matches the detected faces, extracts the contour of the human face to be detected, and calculates the distance d between the middle point of the central connecting line of eyes of the contour and the geometric center of the chin and the area s of the surrounding region of the nose contour. A linear resolution analysis method is utilized to find out the best projection direction w capable of distinguishing between infant faces and non-infant faces. The distance d and the area s are projected in the direction w, and according to the projected points the baby value which expresses the human faces to be detected close to the infant characteristic is obtained. A middle point of two individual central connecting lines is taken as a threshold value K which distinguishes non-infant face and infant face. Whether the target to be detected is an infant or not is judged through comparing the baby value with the threshold value, if so, then taking the target as a track object. The invention also provides an embedded realization system for actively tracking infants.
Owner:SHANGHAI FUKONG HUALONG MICROSYST TECH

Online updating method of principal component analysis monitoring model

The invention relates to an online updating method of a principal component analysis monitoring model. The method comprises the following steps that: 1) A model online updating system comprising data acquisition equipment and a monitoring computer is arranged in industry field; 2) A traditional principal component analysis (PCA) modeling module uses historical data to establish a PCA initial monitoring model; 3) After the monitoring begins, a mean value variance updating module calculates a mean value and a standard deviation sigma' of a new model according to real-time process data and the current PCA model; 4) A projection point calculation module calculates a residual vector of a new sample and transmits to a residual determination module; 5) The residual determination module determines an updating method of a projection direction according to a size of a residual vector die; if the residual is large, a principal component space adjusting module is called; if the residual value is small, a principal component direction fine adjusting module is called; finally a load vector P' nk and a characteristic value matrix lambda' kk of the new model is obtained; 6) A control limit updating module carries out control limit and updating on statistical magnitude of the model; the system finally outputs the new model omega' which is used for online monitoring and fault diagnosis during an industrial process.
Owner:TSINGHUA UNIV

Three-dimensional gesture action recognition method based on depth images

The invention provides a three-dimensional gesture action recognition method based on depth images. The three-dimensional gesture action recognition method comprises the steps of acquiring the depth images including gesture actions; dividing a human body region corresponding to the gesture actions from the images through tracking and positioning based on quick template tracking and oblique plane matching to obtain a depth image sequence after the background is removed; extracting useful frames of the gesture actions according to the depth images after the background is removed; calculating three-view drawing movement historical images of the gesture actions in the front-view, top-view and side-view projection directions according to the extracted useful frames; extracting direction gradient histogram features corresponding to the three-view drawing movement historical images; calculating relevance of combination features of the obtained gesture actions and gesture action templates stored in a pre-defined gesture action library; using a template with largest relevance as a recognition result of a current gesture action. Therefore, three-dimensional gesture action recognition can be achieved by adopting the three-dimensional gesture action recognition method, and the three-dimensional gesture action recognition method can be applied to recognition of the movement process of simple objects.
Owner:INST OF AUTOMATION CHINESE ACAD OF SCI
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