37 results about "Mean value model" patented technology

The invention relates to a merchant passenger flow prediction method fusing a historical mean value and a boosted tree. The method is characterized by comprising the following steps of preprocessing merchant complete behavior data in a time period; constructing features for the preprocessed data; based on the historical mean value and the boosted tree, building a passenger flow prediction model; and performing passenger flow prediction. The invention provides an internet merchant passenger flow prediction model fusing the historical mean value and the boosted tree. The essence of the model isa weighted sum after weight coefficients, calculated by a calculation formula, of a boosted tree model and a historical mean value model are fused according to a certain ratio. The method considers not only how to improve the prediction precision of the model but also a dependency relationship between passenger flow prediction and time, and performs comparative analysis on prediction results of different models.

The invention provides an average value modeling and control method applicable to a VSC-MTDC (Voltage Sourced Converters Multi-terminal Direct Current) system. The method comprises the following steps of 1, building a mathematical model of a VSC based on d and q rotational coordinates, and calculating active power and reactive power of an AC side of a converter by combining a VSC-MTDC power transmission system; 2, building a VSC-MTDC controller by taking the active power and the reactive power of the AC side of the converter as reference values to achieve cooperative control of a plurality of converter stations; and 3, simplifying a control process of the VSC-MTDC, and building a VSC-MTDC average value model. The average value model can be applied to a multi-terminal direct current power transmission system, the simulation speed is greatly increased, the simulation efficiency is improved, and the mathematical calculation amount is reduced.

Disclosed is a battery state of charge (SOC) determining method and a battery managing apparatus that acquires a stochastic reduced order model (SROM) and a mean using battery conservation equations acquired based on a stochastic Pseudo 2-dimensional electrochemical thermal (P2D-ECT) model, measures state information, and assimilates the state information with the SROM and the mean to determine an accurate SOC at a relatively low calculation cost.

The invention discloses a multi-terminal VSC-HVDC (Voltage Source Converter Based High Voltage Direct Current) system droop control coefficient determining method comprising the following steps: first, a DC system state space model containing droop control is built based on a mean value model of VSC, and the action mechanism of droop control is analyzed using the model; and then, a droop coefficient determining problem is converted into an optimization problem with minimum system hybrid sensitivity Frobenius-Hankel norm as the objective based on the system model, and the eigenvalue constraint and steady-state error constraint of a closed-loop system are considered to optimize the stability and robustness of the system. The method can maximize the stability of the system under disturbance and make the system have certain fault ride-through capability. Moreover, the method can be combined with other droop coefficient determining methods, and a droop controller meeting different requirements or achieving different functions can be designed by increasing constraint conditions or changing the optimization objective.

The invention relates to a moving target real-time positioning method based on visible light communication, and belongs to the technical field of wireless communication. The moving target real-time positioning method based on visible light communication, which is provided by the invention, comprises the steps of: by adopting a cellular topological structure, partitioning indoor LED nodes into a plurality of cells, selecting network source center nodes, applying time slot periods by competition, and sending optical signals according to time slots by LEDs; by a terminal, adaptively selecting three LED reference nodes; by adopting an RSS positioning algorithm, according to receiving optical power, calculating transmission distances from the LED reference nodes to the terminal; and carrying out correction on the optical power of a receiving end by adopting a mean value model, and finally, by coordinates and the transmission distances of the LED reference nodes, calculating coordinates of the terminal so as to implement indoor positioning. The method solves the contradiction of excessively large frame length and excessively large number of LED nodes, reduces waiting time delay of a communication system to the greatest degree, solves the problem of influence of channel attenuation caused by LED light shielding and terminal movement on positioning, and has the advantages of low energy consumption, high accuracy, no electromagnetic interference and the like.

The invention discloses a parallel type battery system modeling method based on an SOC compensator, and N battery single bodies are connected in parallel to form a parallel type battery system. The method comprise the following steps: establishing a battery system mean value model according to known lithium ion battery single body performance parameters by utilizing parallel circuit working characteristics and current characteristics of various branch battery single bodies, designing one SOC compensator by utilizing comparison between actual values of the various branch battery currents and a mean value model branch current then, determining a mathematical relationship between the various battery single body performance parameters and a battery system performance parameter then, and establishing a parallel type battery system model. The parallel type battery system model established in the invention can effectively simulate charge and discharge operating characteristics of the parallel type battery system, the modeling method of the invention can be suitable for parallel connection of the battery single bodies and also be suitable for parallel connection of battery modules.

The invention, which belongs to the technical field of medical image processing, discloses a mouse CT image kidney segmentation method based on a random forest and a statistic model. The method comprises: on the basis of a training sample, establishing a high-contrast-ratio organ mean value model and a low-contrast-ratio organ mean value model respectively; estimating the location of a kidney in a target image; extracting features of the training sample and the target image; and training a random forest and completing target segmentation. The feature expression for the CT image is constructed and thus the random forest can segment the CT image precisely, so tat problems of large data volume, complicated random forest calculation, and too low speed for the CT sequence image are solved. Meanwhile, an over-fitting problem caused by the statistic model is solved and a model can be established by using a few of samples; and kidney segmentation in the CT image is realized. The method having advantages of high precision, fast speed, and capability of being free of manual intervention has the great reference application value in fields like medical image segmentation.

The invention relates to a mean value model in a modular multilevel converter (MMC), and a simulation method of the same, and belongs to the field of flexible power transmission, and power electronics. The mean value model in a modular multilevel converter, and the simulation method of the same aim at improving the accuracy of a mean value simulation model in a modular multilevel converter and accelerating dynamic response. The mean value model in a modular multilevel converter includes an alternating current side equivalent model, a direct current side equivalent model and a capacitor equivalent model. The mean value model in a modular multilevel converter, and the simulation method of the same can improve the dynamic response speed of the system by means of a method of extracting the equivalent capacitors individually from sub modules and utilizing the controlled voltage source to control the direct current side. The mean value model in a modular multilevel converter, and the simulation method of the same can control the switches of the alternating current side equivalent model and the direct current side equivalent model, and the equivalent capacitors and equivalent voltage of sub modules at the same time to control the simulation model to realize simulation of stable operation of the MMC, operation in fault, of the MMC, and starting of pre charging at the same time.

The invention discloses an engine hardware-in-the-loop test method and system. The method comprises the steps that a real-time processor receives a simulation test instruction carrying simulation model setting parameters, a real-time simulation composite model is adopted to simulate engine test working conditions corresponding to the simulation model setting parameters, engine measurement signals are obtained, and the engine measurement signals are sent to an engine control unit, the real-time simulation composite model comprises a subsystem simulation Gaussian model and a subsystem simulation mean value model; the engine control unit receives the engine measurement signal, processes the engine measurement signal by adopting a to-be-tested control program to obtain a target control signal, and sends the target control signal to the real-time processor; and the real-time processor receives the target control signal, adjusts the model operation state according to the target control signal by adopting the real-time simulation composite model, and obtains a simulation test operation result. According to the method, in the testing process, the simulation calculation precision is considered, and the real-time performance is guaranteed.

The invention discloses a method for simulating an infrared small target image sequence based on a mean value model. The method comprises the following specific steps: (1), acquiring the background of an image; (2), simulating the background of a target image; (3), expanding a mirror image; (4), establishing a target model; (5), setting a target track; (6), synthesizing the target image; (7), accumulating 1 to the number i of a background frame of a simulated infrared small target image; (8), judging whether the number of the background frame of the simulated infrared small target image added with 1 is equal to the total frame number L of a simulated infrared small target image sequence or not, if so, performing a step (9), and if not, performing the step (2); and (9), outputting the simulated infrared small target image sequence. The method disclosed by the invention has the advantages that: the calculation amount is low; the validity of the simulated infrared small target image is high; texture detail characteristics are enriched; and furthermore, the size, the signal-to-noise ratio, the motion speed and the track of an infrared small target are controllable.

The invention discloses a model design method based on a depth nearest class mean value and an incremental smell classification method. The method comprises the following steps: designing a depth neural network model, wherein the deep neural network model comprises an input layer, at least one hidden layer, a full connection layer and a Softmax function layer; and then replacing a full connectionlayer in the deep neural network model with an NCM layer to obtain a depth nearest class mean value model. According to the model design method based on the depth nearest class mean value and the incremental smell classification method provided by the embodiment of the invention, the advantages of the depth neural network and the nearest class mean value classifier are combined, respective limitations of the depth neural network and the nearest class mean value classifier are eliminated, a new smell class can be seamlessly accommodated, and retraining is not needed. The method is small in calculation amount and wide in application range.

The invention discloses a method for calculating thermal performance of the working process of an air cylinder of a marine main engine. The method is based on a mean value model and a seiliger model, an isovolumetric supercharge ratio a and an isobaric pre-expansion ratio b serve as loop parameters of the seiliger model, the isovolumetric supercharge ratio a and the isobaric pre-expansion ratio b are fitted on the basis of a large number of measured data and correlation theories, and the method is applied to simulation of the working process of the air cylinder of the marine main engine. The method can be used for steady-state calculation of the working process in the air cylinder of the marine main engine, computational accuracy can be improved, and the number of parameters needed for calculation is reduced.

The invention discloses an establishment method of a mean value model and an establishment method of a small signal model. The mean value model includes an MMC body module, a VSG control module, an alternating-current network module and a phase-locked loop module. According to the establishment method of the mean value model, the VSG control module performs calculation on the basis of received active reactive current idref and iqref so as to obtain v<dref>, v<qref>, u<ddiff, ref>, and u<qdiff, ref>; the v<dref>, v<qref>, u<ddiff, ref>, and u<qdiff, ref> obtianed by the VSG control module are sent to the MMC body module, and calculation is performed so as to obtain alternating-current side current isd and alternating-current side current isq; the alternating-current side current isd and thealternating-current side current isq are returned to the VSG control module and sent to the alternating-current network module; the alternating-current network module performs calculation on the basis of the received alternating-current side current so as to obtain PCC point voltages vsd and vsq, and then sends the PCC point voltages vsd and vsq to the phase-locked loop module; calculation is performed, a phase-locked frequency omegapll, and a phase-locked angle thetapll are obtained, and the phase-locked frequency omegapll and the phase-locked angle thetapll are returned to the VSG control module; and therefore, the problem of analysis on the stability of the access of an MMC into a (weak) grid system can be solved.

The invention provides a physical layer optimization simulation method and system for a power grid information physical system. The method comprises: collecting operation parameters of a power grid; initializing a pre-established power grid information physical system physical layer simulation model based on the operation parameters; simulating by adopting a time-varying phasor method based on theinitialized power grid information physical system physical layer simulation model; wherein the power grid information physical system physical layer simulation model comprises a power electronic interface equipment alternating-current and direct-current converter model established by adopting a mean value model technology. According to the method and the system, a mean value model method is provided for a power electronic interface equipment alternating current-direct current converter with a complex model to simplify the model, a physical layer modeling method is optimized, a time-varying phasor simulation method is also adopted to carry out large-scale power transmission and distribution hybrid network time-varying phasor simulation, and the physical side simulation speed is greatly improved.

The invention discloses a modeling method of a power electronic device. The modeling method comprises the following steps: establishing a nonlinear differential equation for a parallel part of each single module; fourier simplification is carried out on the nonlinear differential equation of the parallel connection part; establishing a mathematical model of the cascade part of each phase of each single module, and using the mathematical model to simplify the nonlinear differential equation after the parallel part is simplified again; the equivalent average value model of the power electronic device is obtained based on a nonlinear differential equation obtained after the parallel part of each single module is simplified again, a mathematical model of the cascade part and an external circuit, so that the simulation speed of the model is remarkably improved under the condition that the precision is stable, and the simulation efficiency is improved. Moreover, the average value model can effectively simulate the external characteristics of the power electronic device, neglects the internal dynamic characteristics, and has important theoretical significance and application value.

The invention discloses a doubly-fed wind turbine generator electromagnetic transient simulation starting method based on dual-mode switching, and belongs to the technical field of power system simulation. The method comprises the following steps: determining the initial rotating speed of a draught fan according to the tide result of the doubly-fed induction generator, and determining the initial value of an electromagnetic transient simulation model of the doubly-fed induction generator in an iterative computation mode according to the rotating speed distribution power; enabling the converter to adopt an average value model mode to determine an initial value of simulation calculation of the doubly-fed wind turbine generator; executing electromagnetic transient simulation calculation of a simulation time step, and obtaining a simulation calculation result; and comparing the active power input into the power grid by the doubly-fed wind turbine generator in the simulation calculation result with the active power of the power flow result to obtain a difference value, and if the difference value is smaller than a preset threshold value, switching to a detailed model mode of the converter, and ending the starting process. The flat start of the electromagnetic transient simulation of the doubly-fed wind turbine generator comprising the detailed converter model in the large power grid can be realized based on the tide result and the basic parameters.