185results about How to "Improve numerical stability" patented technology

The invention relates to an electric network parameter estimation method based on the parameter sensitivity of a state estimation residual error, which belongs to the technical field of electric network parameter identification of electric power systems. The electric network parameter estimation method comprises the following steps: deducing the sensitivity of the state estimation residual error for each circuit parameter of an electric network according to an actual electric network model and real-time measuring data; and modifying the circuit parameter on the prior suspicious branch circuit by adopting a linear optimization method, thereby increasing the reliability and the accuracy of application software. The electric network parameter estimation method based on the parameter sensitivity of the state estimation residual error does not have the problems of numerical stability and observation performance and has simple calculation, easy realization and high calculation speed.

The invention discloses a CT imaging system and a method. The method includes: conducting common CT scanning on an object to obtain a common CT image, then determining an area-of-interest in the image, making use of a photon counting detector to perform CT scanning on the area-of-interest from multiple energy windows, and then re-establishing a high resolution image of the area-of-interest. The photon counting detector is employed to collect the photon counting projection data of multiple energy windows, so that decomposition of multiple basis functions can be carried out, the energy spectrum can have high discrimination, and the numerical stability can be good.

A calibration method based on star field for the star-sensitive sensor includes such steps as creating a posture conversion array of star-sensitive sensor, creating the distortion model of star-sensitive sensor, and eliminating the least square parameters.

The invention discloses a meshless RKPM-based two-dimensional thermal deformation and stress analysis method for an anisotropic material structure. The method mainly comprises the following steps of (1) performing RKPM node discrete preprocessing on a calculation model; (2) solving an RKPM thermal deformation displacement value: assembling RKPM overall force stiffness matrix and overall thermal load column vector; applying a boundary, and processing a first boundary condition by adopting a penalty function method; establishing a meshless RKPM thermal stress discrete control equation of the anisotropic material structure, and solving the RKPM thermal deformation displacement parameter value of a node; (3) solving an RKPM thermal stress value: performing approximation on the obtained thermaldeformation displacement parameter value by adopting reproducing kernel approximation to calculate out a thermal stress of a Gaussian point, thereby obtaining the RKPM thermal stress value of the node; and (4) post-processing a calculation result. The two-dimensional thermal deformation and stress analysis of the anisotropic material structure is performed based on a meshless RKPM; and a numerical method is stable and high in precision.

An embodiment of the invention provides an electric-power-system robust state estimation method based on a subsection nonlinear weight function and an apparatus thereof. The method comprises the following steps of constructing a node admittance matrix of an electric power system, a measurement amount measurement equation and a zero injection equality constraint; calculating a jacobian matrix and a measurement-amount residual error of the electric power system and acquiring a weight of each measurement amount; and updating a state variable, determining whether an iteration algorithm reaches a convergence threshold, and if the iteration algorithm reaches the convergence threshold, acquiring a final node voltage amplitude and a phase position of the electric power system. In the invention, bad data detection and identification, and state estimation are simultaneously performed; state estimation calculating is performed, and simultaneously a measurement amount weight can be changed; a bad data weight in iteration is continuously reduced and an influence brought by the bad data is restrained; a calculation amount is effectively reduced and work efficiency is increased; a residual error of the measurement amount is directly introduced into a subsection nonlinear weight function, and standardized residual error calculating is avoided so that a calculating speed can be greatly increased and calculating time is saved; and the method and the apparatus are suitable for an engineering application.

The invention discloses a lithium-ion battery SoC (State-of-Charge) estimation method based on improved and self-adaptive dual unscented-Kalman-filters. The method mainly comprises the following steps: 1) establishing a state filter and a parameter filter of a lithium ion power battery based on an equivalent circuit model; 2) coupling the state filter and the parameter filter of the lithium ion power battery based on the equivalent circuit model, and building dual unscented-Kalman-filters; and 3) inputting operation parameters of a to-be-detected lithium ion power battery into the dual unscented-Kalman-filters, and carrying out parameter correction and stage-of-charge (SoC) estimation on a lithium ion power battery equivalent circuit model. According to the method in the invention, the effectiveness of cholesky decomposition is guaranteed, the problem that iteration is stopped due to the fact that a covariance matrix is indefinite caused by reasons such as an initial value error, noisedisturbance, calculation module floating point error and the like is overcome, and the numerical stability of the filtering process and the robustness of the algorithm are enhanced.

The invention provides a fluid simulating method and device. The method includes the steps that firstly, a mixed flow model is constructed; secondly, smoothed particle hydrodynamics (SPH) particles are constructed; thirdly, relevant information of fluid needed by the mixed flow model is processed in the mixed flow model through an SPH method; fourthly, information needed in fluid simulating is output according to a processing result in the mixed flow model. According to the fluid simulating method and device, the moving process of multi-component fluid can be widely and accurately simulated.

The invention discloses a FastSLAM method based on particle proposal distribution improvement and adaptive particle resampling. The method comprises the steps that 1, a square root transformation unscented Kalman filter is utilized to estimate optimal particle proposal distribution, and the pose state of a robot is sampled; 2, a square root volume Kalman filter is utilized to update feature map information corresponding to each particle; 3, an adaptive particle resampling method based on relative entropy is utilized to determine the quantity of particles needed at the current moment; 4, the pose stat of the robot and guidepost feature map information are determined according to a particle set obtained after resampling. A traditional FastSLAM algorithm is improved from the two aspects of quality and quantity of the sampling particles at the same time, thus, the numerical stability and accuracy of the algorithm in the estimation process are enhanced, and the quality of the sampling particles is improved; in the particle resampling process, the least quantity of the needed particles is dynamically determined according to estimation uncertainty, and therefore the calculation efficiency of the algorithm is improved.

The invention discloses a cubic spline-based infrared thermal image blind pixel compensation algorithm, which comprises the following steps of: obtaining a blind pixel distribution map of an infrared thermal image by blind pixel detection; for each blind pixel point, constructing cubic splines of a row direction and a column direction in a way of taking coordinates of pixels in a row and a column where the blind pixel is in the infrared thermal image as interpolation nodes respectively, calculating interpolated values of the two cubic splines at the blind pixel point respectively, and taking a mean value of the two interpolated values as a primary compensation value of the blind pixel; after all the blind pixels in the infrared thermal image are subjected to the primary compensation, performing secondary compensation on the blind pixels; for each blind pixel point, constructing the cubic splines of the row direction and the column direction in a way of taking the coordinates of the pixels in the row and the column where the blind pixel is and the coordinates of the other blind pixels subjected to the primary compensation in the infrared thermal image as the interpolation nodes respectively, calculating the interpolated values of the two cubic splines at the blind pixel point respectively, and taking the mean value of the two interpolated values as a secondary compensation value of the blind pixel; and traversing all the blind pixels in the infrared thermal image to obtain the infrared thermal image subjected to the secondary blind pixel compensation.

The invention provides a seismic-wave motion equation generating method and a system thereof. The seismic-wave motion equation generating method comprises: obtaining acoustic wave equation data; obtaining geological parameter information; executing arbitrary difference precise integration according to the acoustic wave equation data and the geological parameter information so as to get the seismic spread equation; obtaining the stability condition, the initial input condition and the boundary processing condition; and generating the seismic-wave motion equation by the seismic spread equation, the stability condition, the initial input condition and the boundary processing condition. The method has higher precision and better value stability, can greatly improve the precision and the stability of the calculation with hardly additional computational complexity. The completely matching layer boundary condition which is obtained according to the arbitrary difference precise integration plays a fine attenuating role in the boundary reflection. The method can provide the seismic-wave spread rule study in complex region with a high-precision data system with fine stability.

The invention discloses a method for estimating the state of a three-phase four-wire low-voltage distribution network and belongs to the technical field of three-phase state estimation of distribution networks. The method comprises the following steps of firstly, by using a computer, inputting low-voltage distribution meter-reading electric data and a network structure which are acquired within any time section, and parameter information through a program, and initiating the data, the network structure and the parameter information; then calculating constant item parts of a node admittance matrix and a jacobian matrix; synthesizing a measuring equation and T-end point zero injection equation restriction, and taking a real part and an imaginary part of voltage as state variables to calculate unbalance amount, an index type weight function and the jacobian matrix; finally updating the state variables and performing astringency judgment to realize estimation on the state of the three-phase four-wire low-voltage distribution network. Active power and reactive power of a node can be independently calculated by the method, the adverse influence of bad data on an estimating result is prevented, and the method has the characteristics of high difference resistance, good astringency, good numerical stability and the like. The method is widely applied to the estimation on the state of the three-phase four-wire low-voltage distribution network.

The invention discloses a high-precision real-time stereoscopic visual positioning method utilizing the parallax space bundle adjustment. According to the invention, only a video streaming obtained by a stereo camera is utilized to carry out navigation positioning of a mobile robot, so that the high-precision real-time stereoscopic visual positioning method has complete autonomy; a U-SURF descriptor is utilized to carry out feature matching, so that the high-precision real-time stereoscopic visual positioning method has strong robustness on illumination variation, motion blur and large rotation and scale variation which are generated in the moving process; and due to the utilization of a parallax space bundle adjustment optimizing method, an autonomous navigation vehicle can also be subjected to accurate real-time positioning when traveling for a long distance, so that the high-precision real-time stereoscopic visual positioning method has the advantages of low degree of dependence on an optimal initial value, high convergence rate, high value stability and the like and compared with a stereoscopic visual positioning method utilizing the bundle adjustment, the high-precision real-time stereoscopic visual positioning method has higher positioning precision and higher speed. The integral stereoscopic visual positioning method disclosed by the invention has high calculating speed and can be operated on line in real time.

The invention discloses a robust digital audio watermark embedding and detection method based on polar harmonic transform. Advantages of great frequency domain localization features, multi-scale, redundancy and translation invariance, the features of non-stationary of greatly describing signals and maintaining the shape of the signals and the same length of audio frequency of each sub-band after decomposition with that of the original audio frequency of nonsubsampled wavelet transform are utilized; then great numerical stability of polar harmonic transform is also utilized, and watermarks are embedded in stable torque values to resist the normal signal attack; and then the synchronization code technology is combined. The experimental results indicate that normal signal processing can be resisted and the desynchronization attack can also be effectively resisted so that the method has great imperceptibility and robustness. Besides, the method also has advantages of being simple in design and easy to realize.

The invention discloses a topologic partition based multi-section joint parameter estimation method. A multi-section joint parameter estimation algorithm is utilized for parameter estimation, so that the estimation measurement redundancy of power grid parameters is increased, the influence of error measurement on the power grid parameters is reduced, and the parameter estimation precision is improved. According to the method, in view of the problem of high calculated amount of the multi-section joint parameter estimation algorithm, a power grid is first partitioned according to a topologic connection relation, and a partition based parameter estimation model is established, so that the parameter estimation calculation scale is reduced. According to the method, maintenance parameters of a dispatching system is estimated and calculated, and theoretical estimation values of error parameters in the system are pointed out, so that the operation and maintenance workload is greatly reduced and the management level of the power grid parameters is improved.

The invention provides a background grid adaptive segmenting method in a DC resistivity no-unit method. The method comprises the following steps of determining distribution condition of medium, abnormal member, landform, electrode and the like in a two-dimensional ground electric model, establishing a DC resistivity no-unit method calculating domain, and utilizing an irregularly distributed node discrete ground electric model; covering the calculating domain by means of a small number of rough and simple initial quadrangular grids, setting a control value which guides adaptive segmentation, and performing adaptive segmentation by the background grid according to the control value and a node distribution condition; arranging ng Gaussian integration points xg in each background grid, and obtaining a no-unit method equation set of the region; solving the equation set for obtaining a node electric field value, and calculating the vision resistivity parameter of a viewing point. The methodcan be based on any node distribution discrete model. High adaptability for any complicated ground electric model is realized. The background grid adaptive segmenting method improves value stability and computing efficiency in routine DC resistivity no-unit method forward calculation.

The invention relates to a self-contained navigation method for measurement of an earth ultraviolet sensor, which comprises the following steps of: initializing: utilizing satellite injection information to supply a state initial value and a covariance initial value outlier of a satellite at a starting moment, accumulating geocentric vector information and earth apparent radius information obtained by the ultraviolet sensor for a specified period of time, and then utilizing an outlier eliminating algorithm to eliminate the outlier in the information; batch processing: performing a least square method on the geocentric vector information and the earth apparent radius information after the outlier is eliminated, and calculating a state estimation Xk and a covariance estimation Pk of the satellite at an ending moment of observation; unscented transformation: utilizing the unscented transformation to realize the time updating of the state and the covariance, obtaining a state forecast X(k+1) and covariance forecast P(k+1) of the satellite at the next ending moment of observation; and recursion: continuously accumulating the geocentric vector information and the earth apparent radius information for a period of time, and repeating the steps and performing continuous recursion and calculation, thereby continuously obtaining the estimation of the state of the satellite. According to the method, the precision and the stability of a navigation system are increased.