37 results about "Discretization error" patented technology

An input coordinate sequence is acquired by sampling a handwritten input pattern at predetermined intervals, and a pattern expressed by this input coordinate sequence is approximated by coupling a plurality of line segments to attain line segment conversion. Adjacent angle data φ[i] is generated based on the directions of the respective line segments. At this time, the segment line length along line segments of all the line segments is divided by a predetermined value at equal intervals, and the angles obtained from the directions of the line segments at respective division positions are defined as φ[i]. This φ[i] is compared with a standard pattern (adjacent angle distribution data) prepared in advance to obtain a matching level. In this way, more accurate pattern matching for a handwritten input, which is approximately invariant to affine transformation and can reduce the influence of discretization errors can be implemented.

A variable discretization method for general multiphase flow simulation in a producing hydrocarbon reservoir. For subsurface regions for which a regular or Voronoi computational mesh is suitable, a finite difference / finite volume method (“FDM”) is used to discretize numerical solution of the differential equations governing fluid flow (101). For subsurface regions with more complex geometries, a finite element method (“FEM”) is used. The invention combines FDM and FEM in a single computational framework (102). Mathematical coupling at interfaces between different discretization regions is accomplished by decomposing individual phase velocity into an averaged component and a correction term. The averaged velocity component may be determined from pressure and averaged capillary pressure and other properties based on the discretization method employed, while the velocity correction term may be computed using a multipoint flux approximation type method, which may be reduced to two-point flux approximation for simple grid and permeability fields.

The invention discloses a voltage automatic calibration device, which includes a high precision voltage reference source, multichannel transfer relays, a voltage acquisition module and a single chip control unit, wherein one end of each of the channel transfer relays is respectively connected with the high precision voltage reference source, the other end of each of the channel transfer relays is connected with each of voltage acquisition channels of the voltage acquisition module respectively, the single chip control unit is connected with a control end of each of the channel transfer relays and is connected with the voltage acquisition module through a controller area network (CAN) bus, thereby obtaining channel acquisition voltage of the voltage acquisition module and finishing the calculation of voltage calibration value. The single chip control unit performs voltage calibration on the voltage acquisition module through the CAN bus. Without manual operation, the voltage automatic calibration device avoids battery voltage discretization errors and personal errors, and can guarantee that voltage acquisition precision is promoted from 10 m V to 2 m V.

A method is provided for designing a mask that includes the use of a pixel-based simulation of a lithographic process model, in which test structures are designed for determining numerical and discretization errors associated with the pixel grid as opposed to other model inaccuracies. The test structure has a plurality of rows of the same sequence of features, but each row is offset from other rows along an x-direction by a multiple of a minimum step size, such as used in modifying masks during optical proximity correction. The images for each row are simulated with a lithographic model that uses the selected pixel-grid size and the differences between row images are compared. If the differences between rows exceed or violate a predetermined criterion, the pixel grid size may be modified to minimize discretization and / or numerical errors due to the choice of pixel grid size.

A feedforward control system using a polynomial formula not affected by discretization error is realized in a magnetic disk drive. In one embodiment, the magnetic disk drive is intended to move a head for performing at least one of recording and playback to and from a magnetic recording medium to a target position. The feedforward input has a seek control system computed by a polynominal formula of a time function. The coefficients of the polynomial formula have been derived from boundary conditions including the characteristics of a zero-order hold.

A method for preparing a pattern to be printed on a plate or mask by electron beam lithography comprising the following steps: modelling of the pattern by breaking down this pattern into a set of elementary geometric shapes intended to be printed individually in order to reproduce said pattern and, for each elementary geometric shape of the model; determination of an electrical charge dose to be applied to the electron beam during the individual printing of the elementary shape, this dose being chosen from a discrete set of doses including several non-zero predetermined doses recorded in memory. The set of elementary geometric shapes is a bidimensional paving of identical elementary geometric shapes covering the pattern to be printed. In addition, when the doses to be applied to the elementary geometric shapes are determined, a discretisation error correction is made by dithering.

A digital filter is designed by combining unit filters (L10′, H10′) having a predetermined asymmetric numerical sequence as filter coefficients (H1 to H3). Thus, it is possible to automatically obtain a desired digital filter coefficient only by combining the unit filter. Moreover, a symmetric numerical sequence {−1, 0, 9, 16, 9, 0, −1} / 32 is divided at the center into two parts and one of them is used as the asymmetric filter coefficients (H1 to H3). This reduces the number of taps required for the digital filter designed, eliminates use of a window function, and prevents generation of a discretization error in the filter characteristic obtained.

An analog filter includes a first arithmetic operation section 2-1 having a plurality of sets of processing circuit being cascade connected, each processing circuit having an S / H circuit of plural stages for holding a ΔΣ-modulated signal and an analog adder for adding the input and output signals of the S / H circuit, in which the number of stages of the S / H circuits 11-1, 14-1, 17-1 and 20-1 decreases toward the end of cascade connection, and a second arithmetic operation section 2-2 configured in the same way, which are cascade connected. By using such an analog filter, over-sampling and convolution of a ΔΣ-modulated signal are conducted so that the envelope of the filter output may be a quadratic curve of finite carrier that converges to zero at finite sampling points to prevent phase distortion of an LPF and a discretization error due to a conventional function. Compared with a conventional circuit for over-sampling and convolution, the number of stages of the S / H circuits and the number of adders are small.

The invention discloses a method for observing the flux linkage of an induction motor rotor, which relates to the technical field of motor control. The invention aims to solve the problem that the discretization error is large and the accuracy of the flux linkage observation is low when the conventional flux linkage observer is discretized. The method for observing the rotor flux linkage of an induction motor according to the present invention collects the stator current of the induction motor, establishes a rotor flux observer, uses the improved Euler method to discretize the rotor flux observer and obtains observation values, the described The observed values ​​are used to control the induction motor, and the improved Euler method is a combined discretization method of the forward Euler method and the trapezoidal discretization method. The invention is suitable for the observation part of the rotor flux linkage in the induction motor control, so as to improve the accuracy of the flux linkage observation.

The invention relates to a method and an electric motor arrangement for determining a corrected rotational speed signal. In one step of the method, a periodic rotational angle signal is detected which has a periodic rotational angle error which is dependent on the rotational angle. Converting the rotation angle signal into a digital original speed signal (16), due to the rotation angle error, the digital original speed signal has an interference ripple, and the cycle duration of the interference ripple corresponds to the cycle duration of the rotation angle error . The digital raw rotational speed signal (16) comprises a plurality of sampled values ​​(07), which are spaced apart in time by the duration of the sampling period, the half-period duration of the disturbance ripple of the raw rotational speed signal (16) being determined. Averaging at least one pair of sampling values ​​(07) of the original rotational speed signal (16), the time interval of the at least one pair of sampling values ​​aside from the time discretization error is the interference ripple of the original rotational speed signal (16) The known half-cycle duration. The average value is obtained by averaging. A correction value is formed that is dependent on the sampling period duration and the frequency of the disturbance ripple to account for discretization errors. The corrected rotational speed signal is formed from the difference between the mean value and the corrected value. The correction signal varies in a sawtooth fashion as a function of the difference between the sampling period duration and the period duration of the disturbance ripple, the maximum amplitude of the correction signal also increasing with increasing frequency of the disturbance ripple.

The invention discloses a cycloidal gear tooth curve variable step size discretization method, which comprises the following steps of S1, setting a cycloidal gear tooth curve parameter; S2, deriving out a cycloidal gear tooth curve equation; S3, deriving out a formula of the curvature radius Rho of the practical tooth curve of a cycloidal gear; S4, deriving out an equation of phi relevant to a pressure angle alpha; S5, deriving out an inflexion equation of the cycloidal gear tooth curve; S6, giving the curve linear interpolation initial step size discretization method. The discretization errors and given errors are compared for automatically regulating the closing step size, so that the maximum step size smaller than the closing errors can be obtained; on the premise of meeting the precision requirements, the number of cutting feeding times is reduced; the processing efficiency is improved. The cycloidal gear tooth curve variable step size discretization method provided by the invention has the advantage that the good integral index is realized in the aspects of closing precision, discretization efficiency and calculation speed.

The invention discloses an uncertainty quantification method capable of simultaneously processing numerical discretization, model forms and model prediction deviations, which comprises the following steps: for each model in an alternative model set, firstly estimating numerical discretization errors of the models by calculating on three to four sets of self-similarity encrypted grids to obtain respective confidence intervals; and then constructing a probability box of the attention target quantity through nesting and Bayesian model averaging methods, and finally obtaining the upper limit and the lower limit of the probability. According to the method, uncertainty quantification of numerical discretization, model forms and model prediction deviations can be processed at the same time, and the defects of an existing uncertainty quantification method are overcome.