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228 results about "Newton's method" patented technology

In numerical analysis, Newton's method, also known as the Newton–Raphson method, named after Isaac Newton and Joseph Raphson, is a root-finding algorithm which produces successively better approximations to the roots (or zeroes) of a real-valued function. The most basic version starts with a single-variable function f defined for a real variable x, the function's derivative f ′, and an initial guess x₀ for a root of f.

Longitudinal-transverse-vertical force cooperative control method of distributed electrically driven vehicle

The invention relates to a longitudinal-transverse-vertical force cooperative control method of a distributed electrically driven vehicle. The method is implemented by a vehicle control system: 1) formulation of expected resultant force and moment; 2) optimal distribution of longitudinal, transverse and vertical forces of four wheels; 3) specific execution of the forces. The expected values of the resultant force and the moment of the whole vehicle are obtained by utilizing various information of the vehicle, an integrated tyre force optimization problem is formed by establishing a constraint condition and an objective function, and an optimization solution algorithm is designed for the problem, wherein the optimization algorithm comprises a constraint optimization method which adopts a barrier function method and a Newton method, and a feasible region planning method based on vehicle state continuity. The method does not need to implement different control strategies according to different work conditions of tyres, realizes unified optimal distribution and control of the longitudinal, transverse and vertical forces of the tyres, comprehensively improves the operation stability and the driving posture of the vehicle, and can be applied to driverless operation of vehicles in the future.
Owner:TSINGHUA UNIV

Modeling and optimized dispatching method of electrical series-parallel system on the basis of energy center

The invention discloses a modeling and optimized dispatching method of an electrical series-parallel system on the basis of an energy center. The modeling and optimized dispatching method comprises the following steps: firstly, establishing an electrical network, a natural gas network and an energy hub model, and coupling the electrical network with the natural gas network through an energy hub to form the electrical series-parallel system; then, taking total energy cost as a target function, and considering various constraint conditions to establish an optimized dispatching mathematic model of the electrical series-parallel system; and carrying out solving by a primal-dual interior-point method, importing a slack variable and a barrier parameter in sequence in a solving process so as to change the model into a model which only contains an equality constraint, then, importing a Lagrange multiplier to obtain a Lagrange function, and solving a non-linear equation set formed by a KKT (Karush-Kuhn-Tucker) condition of the Lagrange function by a Newton method. A constructed example simulation result indicates that an optimization effect on the electrical series-parallel system by the modeling and optimized dispatching method is superior to an independent optimization effect.
Owner:HOHAI UNIV

Rectangular coordinate Newton method load flow calculation method with changeable Jacobian matrix

The invention discloses a rectangular coordinate Newton method load flow calculation method with a changeable Jacobian matrix. The method includes the following steps that original data input and voltage initialization are conducted; a node admittance matrix is formed; power and voltage deviations are calculated, and the maximum amount of unbalance delta Wmax is obtained; the Jacobian matrix J is formed; a correction equation is solved and a real part e and an imaginary part f of voltage are corrected; node and circuit data are output. According to the rectangular coordinate Newton method load flow calculation method, a Jacobian matrix calculation method different from that used in the following iteration processes is adopted in the initial iteration process, and the convergence problem of rectangular coordinate Newton method load flow calculation in analyzing a system with a small-impedance branch circuit is solved. When misconvergence happens with conventional rectangular coordinate Newton method load flow calculation, the rectangular coordinate Newton method load flow calculation method with the changeable Jacobian matrix can achieve reliable convergence, and the number of iterations is fewer compared with the prior art. The rectangular coordinate Newton method load flow calculation method with the changeable Jacobian matrix can effectively solve the convergence problem of the conventional rectangular coordinate Newton method load flow calculation in analyzing the system with the small-impedance circuit branch, and meanwhile load flow calculation can be performed on normal systems, and adverse effects are avoided.
Owner:SUWEN ELECTRIC ENERGY TECH

Quick algorithm for joint resource allocation in heterogeneous wireless network parallel multi-access system

The invention discloses a quick algorithm for joint resource allocation in a heterogeneous wireless network parallel multi-access system. When the joint resource allocation is performed in the heterogeneous wireless network parallel multi-access system, the bandwidth and power allocations are separated and the resource allocation is performed in turn, wherein the bandwidth allocation under the condition of equal power allocation is firstly performed; in the bandwidth allocation process, the advantage of high convergence rate of a Newton method is fully taken, thereby reducing the arithmetic complexity and increasing the arithmetic rate; and then the power allocation is performed; and if a power allocation result is a negative value, the bandwidth and the power are allocated again, thereby more fully utilizing the bandwidth and power resources as well as increasing the arithmetic efficiency and rate. By utilizing the algorithm to perform the joint resource allocation in the heterogeneous wireless network parallel multi-access system, the purpose of approaching the acquired resource allocation optimal solution to the theoretical optimum solution is achieved. The algorithm can be used for quickly allocating the joint resource in the heterogeneous wireless network parallel multi-access system.
Owner:XIDIAN UNIV

Load flow calculation method of rectangular coordinate newton method

The invention discloses a load flow calculation method of a rectangular coordinate newton method. The load flow calculation method comprises the following steps: inputting original data and initializing a voltage; forming a node admittance matrix; calculating power and a voltage deviation; forming a jacobian matrix J; solving a modified equation and modifying a real part e and an imaginary part f of the voltage; and outputting nodes and branch data. The calculation formula of partial elements (i=j) of the jacobian matrix obtained in a manner of load flow calculation by utilizing the rectangular coordinate newton method is modified and improved, so that the problem of astringency of the load flow calculation of the rectangular coordinate newton method during the analysis of branch systems containing small impedance is solved. As compared with the fact that the astringency of the small impedance branch systems cannot be realized by adopting the load flow calculation of the conventional rectangular coordinate newton method, the reliable astringency of the small impedance branch systems can be realized by utilizing the load flow calculation disclosed by the invention; and the load flow calculation to normal systems can be carried out at the same time, so that harmful effects are avoided.
Owner:DALIAN MARITIME UNIVERSITY

Newton method power flow calculation method which changes Jacobi matrix with iteration and node types

The invention discloses a Newton method power flow calculation method which changes a Jacobi matrix with iteration and node types. A PQ node calculates a Jacobi matrix element by using an ai value and a bi value which are calculated by given values Pis and Qis in the first-time iteration. A PV node and all nodes in the subsequent iteration calculates the Jacobi matrix element by using a conventional method. The method solves a convergence problem of a rectangular coordinate Newton method power flow calculation method in the analysis of a power system containing a low impedance branch in such a way that the PQ node adopts the Jacobi matrix calculation method in the first iteration process and which is different from that in the subsequent iteration processes. The method of the invention can be reliably converged when he conventional rectangular coordinate Newton method are not convergent, is less than the number of iterations than the prior art. The Newton method power flow calculation method can not only solve the convergence problem of the rectangular coordinate Newton method power flow calculation method in the analysis of a power system containing a low impedance branch, but also can calculate the power flow of the normal power system without any adverse effect.
Owner:DALIAN MARITIME UNIVERSITY

Distributed computation based voltage stability assessment method of sub-networks in interconnected power network

The invention discloses a distributed computation based voltage stability assessment method of sub-networks in an interconnected power network. The distributed computation based voltage stability assessment method comprises the following steps: firstly establishing a simplified external network model which only reserves a regional interconnection line on sub-networks in the interconnected power network; then calculating load margin by a continuation power flow (CPF) method in the main sub-network performing voltage stability assessment calculation, and then calculating by a Newton load flow method under coordination of the other neighboring sub-networks; and by means of voltage information exchange and coordination calculation of boundary nodes in outer loop, continuously correcting equivalent injection power of the boundary nodes outside the sub-networks so as to finally and locally obtain the sub-network load margin which is consistent with the result of whole network unified computation at the main sub-network. The voltage stability assessment method has the beneficial effects that by adopting the simplified external network model of the sub-networks, the Ward equivalent process is avoided so as to reduce the participation degree and calculated quantity of a coordination layer; the calculation mode is basically consistent with that in the current EMS (energy management system), and the independent calculation precision of each sub-network is higher; and voltage stability support and impact of an external power network on an internal power network can be better considered.
Owner:HOHAI UNIV

Method for analyzing limit pretension force of angular contact ball bearing under fixed-position pretension of high-speed electric spindle

A method for analyzing limit pretension force of an angular contact ball bearing under fixed-position pretension of a high-speed electric spindle belongs to the technical field of bearing pretension. According to the method, firstly, parameters including a bearing type, a working condition, maximum permissible stress of a material and the like are determined; secondly, based on a Hertz contact theory, the influences of pretension force, centrifugal force and gyroscopic torque of the bearing are considered, and a kinetic model of the angular contact ball bearing under the fixed-position pretension is established, wherein the kinetic model includes a contact region model of the angular contact ball bearing, a pretension model of the angular contact ball bearing in a static state of the spindle, and a pretension model of the angular contact ball bearing in a rotating state of the spindle; thirdly, a relation between the pretension force and maximum contact stress of a bearing rolling body and bearing inner and outer rings under the condition of rated speed is solved with a Newton method; and finally, the pretension force, i.e., the limit pretension force, of the bearing under the permissible stress of the material is analyzed out.
Owner:BEIJING UNIV OF TECH

Five-axis machining track contour error double closed-loop compensation method

The present invention provides a five-axis machining track contour error double closed-loop compensation method, belongs to the multi-axis numerical control process technology field, and relates to a contour error double closed-loop compensation method configured to improve the five-axis machining precision based on inner ring prediction compensation and outer ring feedback compensation of contour errors. Based on model prediction and feedback correction, the method estimates motion position of each physical axis at the next moment, employs tangential inversing and the Newton's method to calculate tip point contour errors and cutter axis direction contour errors of the next moment and the current moment, and the contour errors are subjected to prediction compensation at the inner ring and the contour errors are subjected to prediction compensation at the outer ring according to inversed Jacobian matrix so as to improve the five-axis machining track contour precision. The five-axis machining track contour error double closed-loop compensation method inhibits the residual errors caused by outside disturbance and model errors on the basis of realizing control of the five-axis machining contour errors in advance so as to have important meanings for improving the five-axis numerical control machining precision.
Owner:DALIAN UNIV OF TECH

Rectangular coordinate Newton load flow calculation method

The invention discloses a rectangular coordinate Newton load flow calculation method; from the basic principle of rectangular coordinate Newton load flow calculation, the invention provides a composition method of Jacobimatrix calculated by rectangular coordinate Newton load flow calculation to improve the convergence of load flow calculation on the basis of analyzing the characteristics of basic modified equation. The method comprises the following steps: inputting original data and initializing voltage; forming nodal admittance matrix; forming Jacobimatrix J; solving the equation and correcting the real part e and the imaginary part f of voltage; and outputting nodal and subcircuit data. The invention corrects partial diagonal element calculation formula of Jacobimatrix J, solving the problem of convergency of rectangular coordinate Newton load flow calculation method when analyzing a subcircuit system containing low impedance; the iterations, possession of the amount of internal memory and arithmetic speed in the invention are all equivalent to conventional rectangular coordinate Newton load flow calculation method when treating system with no low impedance, so the calculated amount is not increased, but is slightly reduced on the contrary.
Owner:DALIAN MARITIME UNIVERSITY

Alternating-current and direct-current power distribution network system load flow computing method based on droop control

The invention provides an alternating-current and direct-current power distribution network system load flow computing method based on droop control. The method includes the following steps that firstly, initialization computing of a sagging curve is carried out; secondly, direct-current power of a direct-current power distribution system is updated through the Newton algorithm; thirdly, according to the updated direct-current power, a middle node voltage equation of an alternating-current power distribution system is solved, and droop characteristics are led into the alternating-current power distribution system; fourthly, whether alternating-current power flow and direct-current power flow converge or not is judged, if no, the second step continues for iterative computation till the alternating-current power flow and the direct-current power flow converge at the same time, and meanwhile a result is output. The invention provides the power flow mixing computing method suitable for a multi-terminal interconnection alternating-current and direct-current power distribution system adopting droop control, the gauss algorithm is adopted in the alternating-current power distribution system, and the Newton algorithm is adopted in the direct-current power distribution system. Meanwhile, the advantage that the gauss algorithm is little in calculation quantity and the advantage that the Newton algorithm is good in convergence are both taken into consideration, the problem that power flow does not converge is avoided, and the practicality level of power flow computing is improved.
Owner:SHANDONG UNIV OF TECH

Frequency selectivity MIMO (multiple input multiple output) system space-time blind equalizer method based on MNM (modified Newton method)

The invention discloses a frequency selectivity MIMO (multiple input multiple output) system space-time blind equalizer method based on a MNM (modified Newton method). The method comprises the following steps that firstly, a multimode method and a soft decision guide method are combined for building a cost function; then, a batch processing mode is adopted, the training sequence length is selected, and the initial value of the blind equalizer is estimated from the known emitted data and the corresponding observing data by a least square method; a newly provided MNM is utilized for calculating the optimal equalizer from observing samples; and finally, the equalizer is utilized for evenly receiving signals, the interference among signals and the interference among codes are eliminated, and resources signals are recovered. The method overcomes the defects that when the exiting MNM is applied to a MIMO system, the calculation quantity is great, and the equalization precision of the existing blind equalization algorithm is low. Compared with the exiting method, the method has the advantages that MNM, MMA and SDD only need little training sample data, and the equalizer can be enabled to be correctly converged to the optimum MMSE (minimum mean square error) equalizer.
Owner:XIDIAN UNIV
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