80 results about "Eulerian method" patented technology

The invention discloses a fluid simulation method based on the Eulerian-Lagrangian coupling method. According to the aim of achieving efficient fluid simulation and the core idea of solving the N-S equation through the Eulerian method and the Lagrangian method to carry out fluid simulation, research is conducted through the multi-method coupling calculation method on the basis of SPH and LBM fluid simulation. Firstly, large-scale fluid field modeling is carried out through the LBM method based on Eulerian grids to build the main part of fluid simulation; then, simulation is carried out on fluid details such as spindrifts and water drops through the SPH method based on the Lagrangian particle idea, LBM fluid and SPH fluid are integrated by designing a coupling algorithm, and lifelike and rapid large-scale fluid simulation with details involved is achieved.

The invention discloses a prediction model based hypersonic aircraft sliding-mode control method. The method is used for solving the technical problem of difficulty in engineering realization by existing hypersonic aircraft adaptive discrete control. The method includes: obtaining a strict feedback form of a height subsystem by reasonable assumption, and building a discrete form of an original system through an Eulerian method; building a four-step prediction model of the original system by unceasing forward prediction, wherein the model only includes an equation; enabling the prediction model to provide the relation of height output at a future time and current system state and control input, wherein the relation can be used for computing numerical values of lumped uncertainties of the system at the historical moment, and the numerical values are used for feedback design of a controller; and combining lumped nominal information further, and using a discrete reaching law to design the sliding-mode controller so that robustness of the system is improved. The prediction model based hypersonic aircraft sliding-mode control method has the advantages that the discrete prediction model is built to acquire system nominal and uncertain information, design of virtual control variables is not needed, the controller is simple and practical in design, and the method is suitable for engineering application.

The invention discloses a time scale function decomposition based hypersonic aircraft actuator saturation control method. The method is used for solving the technical problem of difficulty in engineering realization under the existing hypersonic aircraft actuator saturation condition. The method includes: obtaining a high-speed slow variable subsystem, a speed slow variable subsystem and an attitude fast variable subsystem by time scale decomposition, and building a discrete form of an original system through an Eulerian method; regarding the height and the speed in a fast subsystem design process as constants so as to achieve model simplification; considering actuator saturation limitations, and importing auxiliary control variables to design throttling valve openness and the controlpiston deflexion angle; and designing an updating law of a neural network by importing an auxiliary error variable. The time scale function decomposition based hypersonic aircraft actuator saturation control method has the advantages that computer control characteristics are combined, a discrete model is built, the subsystems are designed according to time scale function decomposition, the actuator saturation condition is fully considered during controller design, and the method is suitable for engineering application.

The invention discloses a method for controlling a neural network of a hypersonic aerocraft on the basis of a prediction model, and belongs to the field of control for aerocrafts. The method is used for solving the technical problem of difficulty in engineering implementation of discrete adaptive control for an existing hypersonic aerocraft. The method includes obtaining a strict feedback form of a height subsystem by means of reasonable assumption, and creating a discrete form of an original system by an Eulerian method; building the four-step prediction model of the original system by means of continuous forward prediction; and adopting a lumped nominal design and error feedback for a controller and estimating and compensating lumped uncertain portions by the neural network. The four-step prediction model contains only one equation and provides the relation among height output at future moments, a current system state and control input. The method has the advantages that features of computer control are combined with the method, the discrete prediction model is built, virtual control variables are not required to be designed, only the neural network is required, and the method is suitable for engineering application.

Embodiments of the present invention provide a novel method and discretization for animating water waves. The approaches disclosed combine the flexibility of a numerical approach to wave simulation with the stability and visual detail provided by a spectrum-based approach to provide Eulerian methods for simulating large-scale oceans with highly detailed wave features. A graphics processing unit stores a one-dimensional texture referred to as a wave profile buffer that stores pre-computed results at a number of discrete sample points for performing wave height evaluation. The water surface is rendered according to water height values computed using the wave profile, accounting for advection, spatial diffusion, angular diffusion, boundary reflections, and dissipation.

The invention relates to a theven equivalent overall modeling method of a modularized multi-level converter (MMC), belonging to the technical field of power transmission and distribution. The electromagnetic transient off-line simulation efficiency of the MMC is determined by the integral computation complexity of a converter part and a modulation voltage-sharing part of the MMC, and the two parts are respectively optimized in three levels by the overall modeling method of the MMC. The core technological scheme provided by the invention is as follows: firstly, assuming the equivalence to be an infinite resistor (ROFF= infinity) when a switch element in a theven equivalent model of the MMC; secondly, discretizing all submodule capacitors in the MMC by adopting a regressive eulerian method, so as to replace a trapezoid integral method in the known model; and finally, providing a novel sequencing and voltage-sharing algorithm by combining the infinite resistor with a turn-off characteristic and the regressive eulerian method, wherein the computation complexity of the novel sequencing and voltage-sharing algorithm is the same as the number of the bridge arm submodules of the MMC. The complexity of the electromagnetic transient simulating calculation of the MMC can be linearly changed along with the increasing of the number of the submodules under the premise of guaranteeing the simulation precision, so that the overall modeling method has important reference significance on researchers in the field of the MMC.

The invention discloses an improved eulerian method-based rapid vector screening and torque predicting control method. The method comprises the following steps: calculating the angle of a stator magnetic chain at the current moment, determining a sector of the stator magnetic chain through a sector judgment module, calculating the electromagnetic torque at the current component, and comparing reference torque and actual torque to generate a torque error; rapidly screening out three optimized voltage vectors, and accurately predicting a stator magnetic chain value and a torque value at the next moment by using a two-order eulerian formula; and finally obtaining the optimal on-off state of an inverter through an optimal value function, converting the on-off state into voltage by the inverter, outputting the voltage to a permanent magnet synchronous motor and driving the motor to operate. By the method, the calculation of a processor is shortened, the predicting value is more accurate, the problems that the permanent magnet synchronous motor model torque predicting control is large in on-line calculation quantity and long in executing time are solved, the predicting results of current, torque and magnetic chain are more accurate.

The invention discloses a fluid simulation method based on video reconstruction and eulerian model coupling. The fluid simulation method comprises the steps of 1) reconstructing a three-dimensional density field of each frame of a fluid according to an input video; 2) solving an N-S equation by adopting an eulerian method, and updating the speed field and density field of the fluid; 3) taking the reconstructed density field of adjacent two frames as prior information and taking the result of the eulerian method as correction to reconstruct a three-dimensional speed field of the fluid; and 4) guiding the eulerian fluid simulation by using the reconstructed density field and speed field to generate a new animation effect. By adoption of the fluid simulation method, the density field and the speed field of the fluid can be reconstructed with relatively high precision; and by tightly coupling the reconstructed data and a fluid geometrical model, a fluid animation effect which is more closer to an actual condition can be obtained, and controllable fluid details can be added.

The invention discloses a self-adaptive RBFNNs noise-measurement active-disturbance-rejection control method for a rotor wing flight manipulator. The method comprises the following steps that the rotor wing flight manipulator is subjected to stress analysis, and a Newton-Eulerian method is used for establishing a dynamics model of the rotor wing flight manipulator; a height controller and a levelcontroller based on RBFNNs\ADRC are designed; according to the dynamics model and the actual flight conditions of the rotor wing flight manipulator, the output of the level controller is converted into an expected attitude angle; an attitude controller based on RBFNNs\ADRC is designed; according to a flight mode of the rotor wing flight manipulator, control signals are converted into all rotor wing rotation speed values. According to the method, self-adaptive RBFNNs are utilized for estimating inner and outer disturbance of all channels of the flight manipulator and conducting real-time compensation, on this basis, the attitude controller based on RBFNNs\ADRC is designed, the disturbance of the movement of the manipulator to a flight platform can be effectively compensated for, and the rotor wing flight manipulator in the flight process can stably grip.

The invention provides a double-rigid-body characteristic point saturation fixed time relative pose tracking control method. The method comprises the steps: establishing a pose kinetic equation of a tracker and a target device based on a Newton-Euler method; establishing a relative pose kinetic equation considering model uncertainty according to the established respective pose kinetic equations ofthe two rigid bodies and the relative pose and the relative speed between the two rigid body feature points; designing a fixed time disturbance observer according to the established relative pose kinetic equation; designing a non-linear saturation compensator according to the established fixed-time non-singular terminal sliding variable so as to solve the saturation effect of an actuator; and combining the established fixed-time disturbance observer and the nonlinear saturation compensator to obtain a model-based robust adaptive controller. The invention relates to the field of control of anautonomous moving body in a three-dimensional space and spacecrafts.

The invention relates to precise control of attitude of a four-rotor unmanned aerial vehicle. In order to provide a nonlinear attitude controller for the four-rotor unmanned aerial vehicle, a controlmethod of finite time convergence attitude of the four-rotor unmanned aerial vehicle is provided. The control method of the finite time convergence attitude of the four-rotor unmanned aerial vehicle includes the following steps that (1) a four-rotor unmanned aerial vehicle kinetic model is established, and the four-rotor unmanned aerial vehicle kinetic model is established through a Newton-Eulerian method; (2) nonlinear controller design comprises roll angle phi nonlinear controller design, pitch angle theta nonlinear controller design, and yaw angle psi nonlinear controller design; and finally, finite time convergence control of unmanned aerial vehicle attitude errors is realized. The control method of the finite time convergence attitude of the four-rotor unmanned aerial vehicle is mainly applied to attitude precise control occasions of the four-rotor unmanned aerial vehicle.

The invention relates to the field of water environment simulation, and discloses a two-dimensional mesoscopic numerical value simulation method of the water age of surface water. A lattice Boltzmann method is combined with a concept of the water age, the water age can be calculated from the essence of particle movement, and therefore, a model can more accurately and efficiently simulate water quality. A hydrodynamic force-water age model is applied to the Danjiangkou reservoir, so that the water quality variation trend of the Danjiangkou reservoir can be predicted, a relocation diffusion rule of pollutant in a water body can be obtained, an area where eutrophication may happen can be predicted, and a scientific basis is provided for reservoir management; through the cross fusion of the lattice Boltzmann method and water age calculation, two water age simulation methods, i.e., an Eulerian method and a Lagrange method, on the basis of the lattice Boltzmann method are developed; a calculated amount generated when the Lagrange method is used for calculating the water age is lowered, the feasibility of the method is increased, and meanwhile, the development of the lattice Boltzmann method in the field of water quality models can be accelerated; and the lattice Boltzmann method is applied to the calculation of the water age of the Danjiangkou reservoir and is further tightly combined with practical research.

The invention discloses an electromagnetic transient simulation interpolation method of a state variable oriented nodal analysis combination frame. The method comprises the steps of respectively building an electromagnetic transient simulation model of a research system on the basis of a nodal equation and a state equation; performing a trapezoidal method integral solution on a combination frame formed by the nodal equation and the state equation from the time t to time t+delta t; detecting all switch motion conditions; changing the state of switches, and rebuilding a transient compute matrix; re-detecting all the switch motion conditions; applying a linear interpolation method to extrapolate the time values including ts and ts+delta t/2 of the nodal equation and the state equation in the combination frame to the time value ts-delta t/2; adopting a two and a half step backward eulerian method to reinitialize the combination frame from the time ts-delta t/2 to the time t+delta t; comparing the context of the time ts+delta t/2 with the time t+delta t, if ts+delta t/2 is greater than t+delta t, performing one-step linear interpolation to obtain the value of the time t+delta t, and otherwise, performing the trapezoidal method integral solution on the combination frame from the time ts+delta t/2 to the time ts+3delta t/2. According to the electromagnetic transient simulation interpolation method, the calculation and reinitialization of the system state at the switch motion moment can be realized so as to eliminate the numerical value vibration problem after the switch moves.

This invention relates to, in order to numerically analyze contaminant transport in groundwater, a method of analyzing contaminant transport under Cauchy boundary conditions using an improved Lagrangian-Eulerian method, wherein problems of a conventional Lagrangian-Eulerian method able to analyze only high Peclet numbers are solved, and which is configured to analyze a new numerical matrix constructed in such a manner that a Eulerian method is applied to an element adjacent to Cauchy boundary conditions and a conventional Lagrangian-Eulerian method is applied to an internal element, thereby enabling accurate numerical analysis of contaminant transport at various Peclet numbers including not only high Peclet numbers but also particularly low Peclet numbers under Cauchy boundary conditions.

The invention belongs to the technical field of paste filling in mining technology, in particular to a paste filling method based on a T-H coupled paste filling slurry pipeline transportation resistance loss calculation method, characterized in that the paste filling slurry is regarded as a homogeneous fluid, the flow field and the temperature field of the paste filling slurry are coupled, the fluid flow is described by the Euler method, the function of the temperature field is described by the differential equation of the fluid heat transfer, the temperature effect is coupled into the energyequation of the fluid flow, and the T-H coupling mathematical model is constructed, the parameters determined by rheometer are further optimized, and then the pipeline transportation characteristics of paste filling slurry in T-H-coupling process are of great significance to the design of paste filling pipeline and the design of paste filling slurry parameter ratio.

The invention discloses a trajectory tracking control method for an unmanned autonomous vehicle. The trajectory tracking control method is specifically implemented according to the following steps: establishing a two-degree-of-freedom kinematics model of the unmanned autonomous vehicle; constructing a trajectory tracking controller based on nonlinear model predictive control, and adding a single-step Euler method into a predictive model of the controller; designing a constraint equation of the nonlinear model predictive controller, and establishing a target function based on the minimum difference value between the control trajectory output of the nonlinear model predictive controller and the reference trajectory; and solving the input of the unmanned autonomous vehicle according to the minimum objective function. A proposed nonlinear model predictive controller can track a reference trajectory more quickly, and has a smaller fluctuation error and a smoother trend in the tracking process. The control method provided by the invention can effectively improve the driving stability and safety of the vehicle, and has great significance for trajectory tracking control of the unmanned vehicle.

The invention provides a method for timely computing the unfixed-point interpolation of a switch within step size. The method comprises the following steps of: computing an electromagnetic transient first step size point status value, and discovering that the switch can move within the step size; carrying out the interpolated value computation on a switch action point status value; computing the next step point size status value from the switch action point; and computing the next whole step size point from the current step size point extrapolated value. When the method is used for computing the switch characteristic circuit, the computing speed of a switch subnet can be improved, and the real-time computation can be preferably carried out. Therefore, the time margin can be provided for improving the computing precision of the switch, the method can be used for the electromagnetic transient simulation computation of the switch characteristic circuit by means of real time, faster-than-real-time and offline, and the whole step size computation can be compatible with various electromagnetic transient switch algorithms and can not limited to the trapezoidal rule, the backward eulerian method, the trapezoidal rule with damp or the modification change assembly of the trapezoidal rule, the backward eulerian method and the trapezoidal rule with damp, so that the computation speed and precision of the simulation can be effectively improved, and the electromagnetic transient real-time computation performance can be optimized.

The invention discloses a pole tower bolt electric torque wrench and a control method thereof. According to the current motor torque and the flux linkage, the motor torque and the flux linkage at thenext moment under different voltage vectors are predicted according to the Eulerian method and a mathematic model of a permanent magnetic synchronous motor, objective function values under the different voltage vectors are calculated according to a wrench target torque value, a stator target flux linkage value and the predicted motor torque value and the flux linkage value at the next moment, andthe voltage vector making an objective function optimal is selected as the voltage at the next moment. A traditional PI regulator is replaced through a prediction model of a stator current and the flux linkage, torque response is fast, and the pole tower bolt electric torque wrench is of good significance to fastening of a pole tower bolt; and by constructing the suitable objective function, everystep of control of a driving motor meets the optimal condition for controlling a target, and the output torque of the pole tower bolt electric torque wrench is controlled in a high-precision mode.

The invention discloses a bridge detection unmanned aerial vehicle autonomous navigation and stability control method based on reinforcement learning. The method comprises the following steps: 1, carrying out dynamic modeling on a four-rotor unmanned aerial vehicle for detecting a bridge based on a Newton-Euler method; 2, considering surrounding environment information and detection constraint conditions of a to-be-detected bridge, and proposing to realize autonomous obstacle avoidance flight of the unmanned aerial vehicle based on neural network reinforcement learning; 3, adopting binocular vision and IMU combined autonomous navigation under the assistance of a bridge building information model; and 4, carrying out attitude control by adopting an active disturbance rejection algorithm in inner loop control of the system, carrying out position control by adopting PID control in outer loop control, and achieving stable control of the bridge detection unmanned aerial vehicle under strong wind interference. The problems that in the unmanned aerial vehicle bridge detection technology, under-bridge positioning signals are lost, and flight control cannot be stabilized under strong wind interference are solved.

The invention belongs to traveling-wave tube simulation techniques, and discloses a Euler method for simulating beam-wave interaction of traveling-wave tubes. Aimed at the problem that calculation precision of existing traveling-wave tubes with the Euler nonlinear theory is low, based on a Lagrangian field theory model, a new treatment method is adopted for electronic phase. The method comprises the steps that Fourier first-order expansion is conducted on the electronic phase; then Bessel function relation is adopted; a nonlinear beam-wave interaction theory model based on a Euler coordinate system is built. The Euler method has the advantages of fast calculation and low memory consumption, the moderate beam-wave interaction process of helix traveling-wave tubes can be precisely simulated, and the method lays a foundation for a study of traveling-wave tube nonlinear theory.

The invention discloses a hypersonic aerocraft Kriging control method based on an equivalent model and belongs to the field of control over aerocrafts, and the method is used for solving the technical problem that the discrete adaptive control of an existing hypersonic aerocraft has difficulty in being realized in an engineering manner. The method comprises the following steps of: firstly converting a height subsystem model of a hypersonic aerocraft into a strict feedback form, and then establishing a discrete strict feedback form of an original system through an eulerian method; and considering the causal relationship of the system and establishing the equivalent model of the original system. The equivalent model can be used for making full use of future output and analyzing historical information of systematic uncertainty; the systematic uncertainty is popularized to a random field by utilizing a Kriging method, and better conforms to the actual condition, the constructivity predication can be carried out, online self-adapting adjustment on parameters is not required, and the method is convenient to implement; by virtue of nominal feedback and error feedback, a controller is designed according to a contragradience method strategy; the controller obtained by virtue of combination of the characteristics of computer control and model conversion can be used for effectively solving the non-causal problem; and the method is suitable for technical application.

The invention discloses a prediction model based hypersonic aircraft Kriging control method. The method is used for solving the technical problem of difficulty in engineering realization by existing hypersonic aircraft adaptive discrete control. The method includes: obtaining a strict feedback form of a height subsystem by reasonable assumption, and building a discrete form of an original system through an Eulerian method; building a four-step prediction model of the original system by unceasing forward prediction, wherein the model only includes an equation; computing historical information of lumped uncertainties of the system according to the prediction model, and performing constructive estimations for future uncertainties by a Kriging method by means of Gaussian random distribution assumption; and further combining lumped nominal information and error feedback to design a controller. The prediction model based hypersonic aircraft Kriging control method has the advantages that design of virtual control variables is not needed, uncertainties of the system are extended from certainties to random distribution by Kriging estimation so as to conform to actual situations more effectively, online parameter adjustment is not needed, the obtained controller is simple and practical in design, and the method is suitable for engineering application.

The invention provides an all-attitude four-axis turntable frame angle instruction resolving method. The method comprises the following steps: establishing a kinematic model of a four-axis turntable frame angle and a total spacecraft attitude angle based on a double-Euler method, initializing the position of each frame angle at the initial moment of simulation, designing a turntable kinematic inverse solution algorithm based on a constraint optimization theory, and according to the kinematic inverse solution algorithm, calculating to obtain each frame angular position instruction of the four-axis turntable at the current moment, and designing a kinematics positive solution algorithm of the four-axis turntable to finally obtain all the instructions of the frame angular positions. By means of the method, it can be guaranteed that on the premise that real-time performance of instruction resolving of the four-axis rotary table is met and kinematics singular positions and the like are effectively avoided, large-amplitude resolving deviation jump in all attitudes is avoided, and the large-amplitude error phenomenon caused by positive solution multiplicity is eliminated.

The invention discloses a method for measuring erosion amount of an aircraft surface under supersonic speed. Conditions of the erosion amount of the aircraft surface can be calculated on the basis of calculation of flow field conditions and grain mass distribution conditions of the aircraft surface in an Eulerian method. According to the method for measuring the erosion amount of the aircraft surface under the supersonic speed, the calculated erosion amount of a three-dimensional aircraft is good in accuracy.

A method for solving high-dimensional nonlinear filtering problems is revealed. The method uses a fast computational module to solve an equation and get approximate numerical solutions of a signal-observation model. The equation-solving process of the fast computational module is speeded up by a transformation module and the computational stability is further improved. D-dimensional nonlinear filtering problems are solved and approximate numerical solutions are obtained based on Yau-Yau filtering theory. A Quasi-Implicit Euler Method (QIEM) is applied to solve the Kolmogorov equations and estimate approximate numerical solutions of the signal-observation model. Moreover, QIEM is more efficient and the numerical solutions are more stable by Fast Fourier transformation (FFT) acceleration.

The invention discloses a simulation method for predicting the solidification process of a vacuum consumable melting cast ingot, and relates to the technical field of vacuum consumable arc melting. The simulation method comprises the following steps: establishing a mathematical model related to an electromagnetic field and a flow field, carrying out mesh generation on a geometric model, adopting an Eulerian-Eulerian method, setting three phases: molten metal, equiaxed dendrites and columnar crystals, and obtaining related material attributes; setting relevant boundary conditions and relevant dynamic grid parameters, and simulating flowing and solidification of molten metal in the vacuum consumable arc melting process and distribution of an electromagnetic field and a solidification structure. According to the method, the rising process of the molten pool and the solidification process of the cast ingot in the vacuum self-consuming arc melting process are simulated, the flowing form of the molten metal in the solidification process is obtained, the capacity of predicting macrosegregation of the cast ingot is achieved, and the method plays an important guiding role in optimizing the vacuum self-consuming arc melting process to obtain the cast ingot with uniform components; and the method is of great significance to actual production.