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56 results about "Curvilinear coordinates" patented technology

In geometry, curvilinear coordinates are a coordinate system for Euclidean space in which the coordinate lines may be curved. These coordinates may be derived from a set of Cartesian coordinates by using a transformation that is locally invertible (a one-to-one map) at each point. This means that one can convert a point given in a Cartesian coordinate system to its curvilinear coordinates and back. The name curvilinear coordinates, coined by the French mathematician Lamé, derives from the fact that the coordinate surfaces of the curvilinear systems are curved.

Method for high-precision reverse time migration imaging based on severe relief surface ground penetrating radar data

The invention relates to a method for high-precision reverse time migration imaging based on severe relief surface ground penetrating radar data. The method comprises the following steps of 1) generating a body-fitted grid discrete relief surface model; 2) decoupling from a Maxwell equation, so as to obtain a Cartesian coordinate system TM (transverse magnetic) wave equation; 3) performing reverse time extrapolation on a receiving wave field in a curvilinear coordinate system from maximum time to zero time; 4) using a sub-wave with setting certain frequency in the curvilinear coordinate system as a forward modeling sub-wave, and performing forward modeling to calculate the positive continuation wave field value at each time; 5) repeating the steps 3) and 4) on the whole profile, removing the low-frequency interference, and finally superposing, so as to obtain the complete migration profile. The method has the advantages that the frequency dispersion effect caused by the step grid at the relief surface in the Cartesian coordinate system is decreased, the interference by the low-frequency noise in the reverse time migration imaging process is favorably reduced, the reflective wave and diffracted wave in the ground penetrating radar data at the relief surface are accurately migrated and regressed, and the underground structure information is truly reflected.
Owner:CHINA UNIV OF GEOSCIENCES (BEIJING)

Method for detecting cutter tooth flank surface wear characteristics of high-feed milling cutter

ActiveCN109940461ASolve the impact of accuracySolve the problem of the influence of cutting vibrationMeasurement/indication equipmentsWear testingMilling cutter
The invention discloses a method for detecting cutter tooth flank surface wear characteristics of a high-feed milling cutter, and belongs to the field of milling cutter detection. Cutter tooth flank surface wear characteristics cannot be completely revealed in the prior art. The method comprises the steps of carrying out cutter tooth flank surface wear testing of the high-feed milling cutter to obtain a cutter tooth flank surface wear state, carrying out structure and cutter tooth error measurement to obtain cutter tooth error distribution characteristics, carrying out cutting vibration testing to obtain variation characteristics of milling vibration signals, carrying out cutter tooth flank surface wear boundary measurement to obtain cutter tooth cutting edge and flank surface wear boundary curve coordinate values, constructing a cutter tooth flank surface wear boundary curve, extracting cutter tooth cutting edge and flank surface wear boundary curve characteristic parameters, and analyzing cutter tooth flank surface wear characteristics to obtain the influence characteristics of the cutter tooth error distribution on cutter tooth cutting edge and flank surface wear and obtain theinfluence characteristics of the milling vibration on cutter tooth cutting edge and flank surface wear. The change characteristics of the cutter tooth cutting edge and flank surface wear along with the cutting stroke can be completely revealed.
Owner:HARBIN UNIV OF SCI & TECH

Electronic whiteboard trace tracking method and apparatus

The present invention discloses an electronic whiteboard trace tracking method and apparatus. The method comprises the steps of: marking at least one to-be-tracked trace curve; calculating distances between each sample coordinates and curvilinear coordinates of the last point in each trace curve successively, and determining a distance minimum among the distances; setting a distance threshold; and comparing the distance minimum with the distance threshold, and if the distance minimum is greater than the distance threshold, setting the sample coordinates corresponding to the distance minimum as a starting point of a new trace curve, or otherwise setting the sample coordinates corresponding to the distance minimum as new curvilinear coordinates of the trace curve where the curvilinear coordinates corresponding to the distance minimum are located. The apparatus comprises a calculation module and a comparison module which are successively connected. According to the method and apparatus provided by the present invention, the distance threshold and an angle threshold are set for further determination of the calculated distances and a vectorial angle during the electronic whiteboard touch trace tracking process, so that the sample coordinates can be matched on the trace curve more accurately, and tracking errors such as point breaking and track crossing are avoided.
Owner:SHENZHEN HONGHE INNOVATION INFORMATION TECH CO LTD

Method for measuring image principal point coordinates and distortion coefficient of linear target

InactiveCN102800084AReduce duplicationDuplicate photography video savesImage analysisComputer visionPrincipal point
The invention discloses a method for measuring the image principal point coordinates and distortion coefficient of a linear target. The method comprises the following steps of: 10, imaging a symmetry axis linear equation of a curve target: fitting the measured object, and calculating the slope of the symmetry axis of the measured object; converting the image points of the measured object to the coordinates of the curve coordinate system; reckoning the coefficient of a parabolic equation; converting the vertex of the parabola to the coordinates of the image coordinate system; and establishing a linear equation of the symmetry axis of the measured object; 20, reckoning the principal point coordinates of the image; and 30, measuring the image distortion coefficient: selecting an image point from the measured object, and obtaining two-dimensional coordinates of the image point in the image coordinate system; establishing a distortion coefficient equation; recovering the distortion so that the measured object becomes a line from a curve; giving the normal equation of the measured object; and establishing the normal equation of the measured object and reckoning the distortion coefficient of the image. The measuring method can be used for measuring the image distortion coefficient and principal point coordinates of the imaged picture.
Owner:SOUTHEAST UNIV

Device for controlling constant power of excavator

The invention provides a power adjusting system of a plunger type duplex tilting tray variable pump. The system comprises a pressure sensing transmitter set, the plunger type duplex tilting tray variable pump, a power adjusting module, a computer host controller and an engine. A measurement numerical value of the pressure sensing transmitter set is transmitted to the computer host controller; the computer host controller adjusts the plunger type duplex tilting tray variable pump through the power adjusting module; the computer host controller comprises a three-dimensional dot-matrix type MCU constant power controller composed of a single chip microcomputer; curvilinear coordinate parameters with lattice parameters composed of three-dimensional arrays are searched according to numerical numbers, collected by the pressure sensing transmitter set, of pressure output by the plunger type duplex tilting tray variable pump, then the power adjusting module is controlled to adjust flow output by the plunger type duplex tilting tray variable pump, so that power, absorbed by the plunger type duplex tilting tray variable pump, of the engine keeps constant, the plunger type duplex tilting tray variable pump is adjusted in a mode approaching to a real constant power curve in the practical work process, the capacity of the engine can be played fully, the flow of the plunger type duplex tilting tray variable pump when a system overflows can be lowered greatly, power loss is reduced and fuel oil is saved.
Owner:山重建机有限公司

Deformation finger print matching method based on curve coordinate system and transferred reference node

The invention discloses a deformed fingerprint matching method based on a curvilinear coordinate system and transference of reference minutiae. The method comprises the following steps: (1). a fingerprint image is represented that I(m*n),O(i, j) belonging to [0, pi) is the local ridge orientation at the pixel (i,j), and each minutia in the fingerprint image I is described by coordinate, direction and type; (2). X axis and Y axis of the curvilinear coordinate axes are extracted from each minutia by taking each minutia as an origin based on a ridge mode and an orientation field of the minutiae; (3). scales of the curvilinear coordinate axes are computed; (4). the coordinate relation between every two minutiae mi and mj are computed; and (5). The minutiae are matched by the method based on the transference of the reference minutiae: provided that a template fingerprint image T and an input fingerprint image Q contain p minutiae and q minutiae respectively, C(T) equals (Ci, j<T>), C(Q) equals (Ci, j<T>), wherein, i is not less than 0 and j is less than q; T and Q are matched by utilizing the minutiae of the C(T) and C(Q) pair to compute the matching minutiae. The method has the advantages of high identification accuracy rate, high efficiency and simple algorithm.
Owner:ZHEJIANG NORMAL UNIVERSITY
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