85 results about "Maximum principle" patented technology

The invention discloses a fault positioning method for a transmission line and belongs to the technical field of power systems. The fault positioning method comprises the following steps: arranging a Rogowski coil-based broadband core-through traveling wave detection device on the high-voltage transmission line; acquiring a current traveling wave signal of a three-phase line; performing singular value detection by applying the phase mode conversion and wavelet mode maximum principle; accurately identifying the traveling wave line mode wave head, and accurately determining the wave head arrival time by using a GPS high-precision clock; and measuring the wave speed of real-time traveling wave mode on line according to different wave head time difference information to realize accurate fault positioning. The fault positioning method has the advantages of effectively avoiding two main factors influencing the traveling wave fault positioning precision, along with high positioning precision and accurate and reliable fault positioning result.

The invention provides a multi-robot path planning and coordination collision prevention method based on fuzzy logic. The method comprises the steps of confirming an input variable and an output variable of a fuzzy controller by setting up the fuzzy controller with robots as a system, using related languages to describe the input variable and the output variable of the fuzzy controller, confirming a qualitative reasoning principle according to the fuzzy control theory, setting up fuzzy control rules according to input signals and output signals of the fuzzy controller, selecting a subordinating degree function of each input language variable and a subordinating degree function of each output language variable, finally, conducting defuzzification, conducting voting on the basis of the maximum principle of the subordinating degree functions, conducting corresponding motions on the robots, and completing the task for planning a path of a single robot. On the basis of the method, the other robots are regarded as dynamic front barriers, and the aim of coordination collision prevention of the multiple robots can be achieved.

The implementation mode of the invention provides a time and frequency synchronization method in a wireless communication system, which comprises the steps of carrying out the symbol timing estimation and the fine frequency estimation on received signals based on the Orthogonal Frequency Division Multiplexing (OFDM) technique; carrying out the timing estimation on the Packet Switching Service (PSS) through the matched filtering of the received signals; determining at least two continuous OFDM symbols as candidate OFDM symbols containing the PSS; shifting the candidate OFDM symbols compensated by the fine frequency estimation into a frequency domain; carrying out the cyclic shift channel estimation on the corresponding sub-carriers of each candidate OFDM symbol of the at least two candidate OFDM symbols; shifting the cyclic shift channel estimation result of each candidate OFDM symbol into a time domain; figuring out the energy value of each sampling point according to the time-domain channel impulse response of each integer-frequency-offset value; and determining the OFDM signals containing the PSS and the calculated value of the integer-frequency-offset value based on the energy maximum principle.

The invention discloses an optimal orbital transfer method of a low-earth-orbit satellite under a limited thrust by taking J2 perturbation into consideration, relates to the optimal orbital transfer method of the low-earth-orbit satellite, and belongs to the field of aerospace. The optimal orbital transfer method comprises the following steps of: establishing a dynamic equation of a spacecraft by taking the J2 perturbation into consideration; solving a Hamiltonian function H corresponding to an optimal fuel consumption performance index according to the states of the spacecraft at the beginning and the end; solving an optimal control rate and a corresponding covariance equation according to a pontryagin maximum principle; constructing a two-point boundary value problem shooting equation set meeting the optimal fuel consumption according to an optimal control condition of a variational method; solving the two-point boundary value problem shooting equation set according to the states of the spacecraft at the beginning and the end as well as the flight time to obtain the optimal control rate formed by an optimal thrust control direction and an engine switching function; and controlling the orbital transfer of the satellite by using the control rate, so that the real-time performance and the orbital transfer precision in the transfer process of the low-earth-orbit satellite can be increased, and the fuel consumption required for the orbital transfer is reduced. The optimal orbital transfer method disclosed by the invention is suitable for the orbital transfer process of the low-earth-orbit satellite when a limited thrust model is adopted by an engine.

The invention discloses a method for obtaining parity check matrix of rate-compatible low-density parity-check codes, comprising the following steps of: selecting a mother code matrix and determining the size of a basic extension matrix; dividing the basic extension matrix into six sub-matrixes (see the formula at right side); according to a minimum ring maximum principle, respectively determiningthe value of each sub-matrix; subsequently combining each sub-matrix to form the basic extension matrix; finally correcting the obtained basic extension matrix by using a current extension factor z and extending the corrected basic extension matrix by using a matrix P with the size of z*z, thus obtaining a parity check matrix; and using the parity check matrix to carry out the LDPC coding to thedata to be coded. When the method and the coder are applied,on one hand, the rate compatibility can be realized; on the other hand, as the minimum and maximum principle is adopted to determine the value of each sub-matrix in each basic extension matrix, the decoding performance can be improved compared to the LDPC codes realizing rate-compatibility by a punching way.

The invention provides a post-evaluation method for comprehensively evaluating power grid science and technology projects. The post-evaluation method includes the following steps of step one, firstly establishing an index set U=(u<1>, u<2>...u<n>) and a judgment set Q=(q<1>, q<2>...q<m>); step two, calculating a comprehensive membership vector using an operator of a generalized fuzzy synthetic operation, and obtaining an ultimate evaluation result according to a membership degree maximum principle. By means of the post-evaluation method, professional experience of industry experts is considered, and subjective judgment with large deviation is avoided, so that arrangement of index weighting is more accurate; during a multi-stage fuzzy comprehensive evaluation process of the power grid science and technology projects, acquiring of index data is normalized by subdividing content options of ground layer indexes, standards for multi-stage fuzzy comprehensive evaluation are unified, and accuracy of evaluation results is guaranteed.

The invention relates to the field of neural network technical methods, in particular to a road network sub-region division and evaluation method based on Canopy + Kmeans clustering, which takes real-time acquisition of road section center latitude and longitude, road section average speed and road section average density as sample data, and comprises the following specific steps: (1) carrying outdata preprocessing; determining a plurality of Canopy and Canopy center points by adopting a Canopy algorithm based on the minimum and maximum principle; (2) after the step (1), carrying out Kmeans secondary clustering; collecting Canopy center points in the step (1), wherein the number of the Canopy center points is the K value of the Kmeans algorithm; and (3) after the step (2), respectively calculating Euclidean distances from each data point to K clustering center points, and dividing the Euclidean distances into a cluster with the minimum distance to form a new cluster. The road networksubarea division method based on a Canopy-Kmeans clustering algorithm is provided by taking road section center longitude and latitude, road section average speed and road section average density which are acquired in real time as sample data, so that the defects of the Kmeans algorithm are overcome.

The invention relates to a method for identifying abnormity of state parameters of a wind turbine generator based on fuzzy comprehensive evaluation. The method comprises the following steps: S1, obtaining the mean absolute error of a test sample according to a selection result of a state parameter generalized fuzzy abnormity identification model so as to obtain weights of various prediction models; S2, realizing state parameter prediction in a time interval to be analyzed through the various prediction models; S3, realizing condition analysis of state parameters through the residual error of the various predication models so as to obtain residual error abnormity indexes of various models; S4, calculating fuzzy membership degrees of various indexes to form a fuzzy evaluation matrix, and calculating an output layer evaluation value; and S5, inputting an evaluation result according to the membership degree maximum principle, and taking a corresponding comment as the evaluation result. The method disclosed by the invention is based on SCADA data of a wind power plant; the method is easy in programming realization; abnormity of parameters can be reflected accurately and effectively; and the identification accuracy of abnormity of the state parameters can be increased by comprehensively considering the abnormity identification results of the plurality of prediction models.

The invention discloses a high-speed train automatic driving energy-saving optimization method based on a maximum principle. The method comprises the steps: firstly building an operation model of a high-speed train according to the mechanical and kinematic characteristics of the high-speed train in an operation process, and obtaining an optimization function of the energy-saving operation of the high-speed train; secondly, constructing a Hamiltonian function according to the principle of the maximum value of the numerous and numerous Delisia gold, and analyzing, solving and analyzing a drivingstrategy of energy-saving operation of the high-speed train; secondly, calculating the running time of the high-speed train according to the traction characteristic curve, the kinetic equation and the driving strategy of the train; finally, the obtained time is compared with standard time, if the obtained time is larger than the standard time, the cruise time is increased properly, otherwise, theinertia time is increased until the total running time reaches the range of the standard time, an energy consumption value is output, and energy-saving automatic driving of the high-speed train is achieved. The method disclosed by the invention can achieve the purpose of energy saving optimization on the premise of ensuring accurate parking, punctuality and comfort.

The invention provides a network health degree testing method and a network health degree testing system. The method comprises the following steps of: acquiring multiple characteristic values of a network; setting preset health degrees for characteristic combinations of the characteristic values respectively; calculating the maximum entropy value of each characteristic combination based on the maximum entropy principle; and taking the preset health degree of the characteristic combination corresponding to the maximum entropy value as the health degree of the network. The sorting operation state of the current network is obtained aiming at the operation characteristic of the current network by acquiring the conventional network states and using the maximum entropy principle and finally revealed in a form of health degree, so that evaluation of the network health degree is realized, subjectivity and inaccuracy of human evaluation are overcome, and the problem of difficult human evaluation under the complex network condition is solved.

The invention discloses a temporary plugging diverting method for achieving liquid-solid-liquid phase conversion by means of a natural geothermal field. The temporary plugging diverting method for achieving liquid-solid-liquid phase conversion by means of the natural geothermal field comprises the steps that (1) the horizon of a reservoir needing temporary plugging is determined, and whether the reservoir needing temporary plugging is a crack or hole is determined; (2) the diversion plugging strength of the temporarily plugged reservoir is larger than or equal to the difference between the maximum principle stress and the minimum principal stress of the stratum is determined; (3) the plugging capacity of the horizon of the temporarily plugged reservoir and the crack or the hole are testedthrough flowing experiments of a core and the crack or pipe flow, and the use amount of a temporary plugging diversion system is worked out; (4) according to the distribution curve of the temperatureof liquid in an oil pipe in a shaft, the peak of bottom hole temperature is obtained; (5) an appropriate temporary plugging diversion system is determined; (6) the use amount of displacing liquid is determined, wherein the use amount of the displacing liquid is larger than or equal to the sum of the volume of the shaft and the volume of a liquid infusion pipeline; (7) site operation is organized.According to the temporary plugging diverting method for achieving liquid-solid-liquid phase conversion by means of the natural geothermal field, liquid is infused into the plugged reservoir, the plugged rack and the plugged hole to achieve effective plugging, liquid-solid-liquid change is achieved by means of the natural geothermal field, the requirements of the temporary plugging diversion technology are met, extra addition of gel breaker is not needed, and the application range is wide.

The invention relates to the electric vehicle power assembly design field, to be specific, relates to an electric vehicle traction motor design parameter verification method. The electric vehicle traction motor design parameter verification method comprises (1) arrangement of a uniform motion calculation module and an accelerated motion calculation module; (2) arrangement of a highest speed calculation module, a common speed calculation module, and a maximum gradient calculation module; and arrangement of an accelerated motion condition calculation module; (3) arrangement of a verification module; (4) selection of verification values according to a maximum principle. The electric vehicle traction motor design parameter verification method has advantages of simple process, comprehensive verification, and reasonable result.

The invention discloses a damsite flood restoration method based on a Copula function. A joint distribution function of damsite peak flow before a reservoir is built, computative reservoir-in peak flow and peak flow time is constructed according to the Copula function, a joint distribution function of damsite flood volume, commutative reservoir-in flood volume and peak occurring time is constructed, a most probable value function of the damsite peak flow and the damsite flood volume is derived on the basis of the conditional probability density maximum principle of the joint distribution function, reservoir-in flood data after the reservoir is built is substituted into the most probable value function, a most probable value of the damsite peak flow and the damsite flood volume is solved, and therefore reservoir-in flood volume process data after the reservoir is built are restored to damsite flood. According to the damsite flood restoration method based on the Copula function, a strong statistic basis is achieved, the compound mode of the damsite flood and reservoir-in flood is unique, and the characteristics of an actual measurement sample can be objectively reflected; the internal relatedness among all the characteristic quantities are fully considered, and a reference basis which is important and strong in operability can be supplied to the reservoir to restore the damsite flood according to the reserivoir-in flood data.

The invention relates to a method for segmenting a sulus basin on the surface of a pallium of a three-dimensional cerebral magnetic resonance image. The technical characteristics lie in that originally messy principle direction fields are dispersed on the surface of the triangularized pallium to generate a biggest smooth principle direction flow field. The core concept of the biggest principle direction dispersion is as follows: an energy function is minimized in the sulus and gyrus regions, wherein the absolute value of the maximum principle curvature is big and the generated biggest principle direction flow field is close to the original principle direction field; in other flat pallium regions, the generated biggest principle direction flow field changes smoothly. Compared with other methods, the method has the main advantage that the tracking method of the biggest principle direction flow field can fully utilize the geometry structure information of the surface of the pallium and can naturally form accurate boundaries among sulus basins although the sulus basins are possibly of asymmetrical structures.

The invention discloses a city CA model establishment method based on a maximum entropy principle. The method comprises the steps that two-stage land utilization grid data is acquired and reclassified; the classified data is superimposed to obtain a city land utilization increase range, and random sampling and coordinate calculation are conducted in the range to obtain sample point data; a space variable influencing city land utilization extension is processed, and a result is used as a classification model constraint condition; a sample point and the constraint condition are used for model training to obtain a classification model with the maximum conditional entropy; a land utilization matrix and a cell corresponding to a matrix element are established, a space coordinate of the cell isinput into the model, the conditional probability of each cell classified as urban land under influence of the constraint condition is obtained and used as the CA model cell transition probability, and a city extension CA model is established on the basis of the CA model cell transition probability and in combination with neighborhood constraint. According to the method, the CA model with the maximum entropy is established and applied to urban land extension simulation, the randomness problem is considered, and the method helps to more precisely simulate city development.

The invention relates to a fault voting line selection method by using Prony relative entropy. The method comprises that when a bus zero sequence voltage instantaneous value is 0.15 times larger than a nominal voltage, a fault line section device is immediately started, a Prony method is adopted for matching a transient state zero sequence current signal in a first T/4 cycle of each branch circuit after a fault; transient state dominant component of superficial characteristics fault characteristic information is selected according to a amplitude maximum principle; and then, transient state dominant component relative entropy of each branch circuit relative to other branch circuits is obtained; and finally, the fault voting line selection mechanism adopting preliminary voting, k value checkout, and final voting are put forward to vote for each branch circuit, so that a faulty line is selected. Theoretical analysis and a large number of simulations indicate that fault voting line selection method can effectively avoid influence of current transformer flux density saturation to line selection, and can greatly improve reliability of fault line selection results.