22 results about "Characteristic equation" patented technology

This invention provides a method and instrument for measuring the thickness of multilayer films based on Taylor polynomial fitting coefficient analysis. The method involves acquiring the interference signal of the multilayer film under test output by a shared-arm interference structure, wherein the reference optical path of the shared-arm interference structure and the sample optical path share the same physical transmission optical path. The interference signal is down-processed to obtain a baseband interference signal with a center frequency near zero. Taylor polynomial expansion is performed on the baseband interference signal at the point where the optical path difference is zero, and a Taylor expansion coefficient sequence is obtained. A linear equation system is constructed based on the Taylor expansion coefficient sequence, and the coefficients of the characteristic equation are solved. The optical path difference corresponding to each layer of the multilayer film under test is obtained by solving the characteristic equation. The physical thickness of each layer is calculated based on the optical path difference corresponding to each layer and the refractive index of the film material.

A kind of X-ray telescope support truss hierarchical thermal control method and system based on frequency domain analysis, the method includes establishing physical domain heat transfer model and carrying out model reduction, extracting first-order linear characteristic equation;Through the frequency domain analysis of characteristic equation, the transfer law of equivalent heat transfer coefficient G and equivalent absorption coefficient λ to different frequency band thermal disturbance is quantitatively revealed, and the design target of passive insulation and active control is determined accordingly;Based on the conclusion of frequency domain analysis, a two-stage passive suppression system composed of individual isolation and system isolation is constructed to attenuate low-frequency platform disturbance, while the upper and lower datum plates are optimized for differential passive thermal characteristics, and an active control loop operating at a specific high frequency band is configured, ultimately forming a frequency domain collaborative temperature control mechanism of passive low-frequency suppression and active high-frequency control.The present application realizes ultra-high temperature stability at low energy consumption cost in extremely complex thermal environment, effectively solving the problem that the precision and energy consumption of traditional thermal control method are difficult to be considered in through structure.

This invention discloses an ADRC method for attenuating periodic disturbances in time-delay systems, belonging to the field of automatic control technology. The method includes: 1. Obtaining the controlled process model and disturbance frequency, and establishing an extended state model containing the periodic disturbance; 2. Constructing a reduced-order extended state observer and tuning the gain using the bandwidth parameter method; 3. Introducing a pure time-delay module into the observer's output channel to construct an ADRC structure; 4. Revealing the mechanism by which periodic disturbances in time-delay systems cannot be attenuated through two-degree-of-freedom equivalent transformation analysis; 5. Based on the frequency domain characteristic equation, analytically determining the delay of the time-delay module to achieve effective attenuation of periodic disturbances at specific frequencies. This invention solves the problem of attenuating periodic disturbances in time-delay systems without significantly increasing structural complexity. Compared to traditional schemes that require high-gain or complex prediction structures, this invention only requires adjusting the pure time delay of the observer's output channel, and the parameter tuning process is clear and intuitive, significantly lowering the threshold for engineering applications.

This invention discloses a method and device for measuring the flow rate of a condensate feedwater system oriented towards edge computing. The method includes the following steps: Step S1, extracting pump operating parameters under multiple typical operating conditions from a historical database of an industrial internet platform; Step S2, performing simulation modeling of the condensate feedwater system, and constructing a nonlinear mapping relationship between the pipe resistance coefficient and flow rate by combining the pipe geometry, fluid properties, and pump mechanical characteristics, thus obtaining the pipe resistance equation; Step S3, simultaneously solving the pipe resistance equation and the centrifugal pump head-flow characteristic equation using the Newton-Raphson iterative method to obtain the theoretically calculated flow rate value; Step S4, comparing the theoretically calculated flow rate value with the real-time measured flow rate value, and dynamically adjusting the model parameters to ensure that the model error is less than a set threshold. This invention achieves high accuracy in measuring the flow rate of the condensate feedwater system.

This invention discloses a time-delay compensation control method for wave energy converters, belonging to the field of wave energy converter control technology. Based on the physical model of the wave energy converter, this method establishes the dynamic equations of the wave energy converter system. After defining the maximum power control problem of the wave energy converter, the dynamic equations of the wave energy converter system are transformed into a second-order linear system form, obtaining the system state variables, system parameters, and input time delay. After constructing an auxiliary system, an error variable is defined. Based on the error variable, a virtual control law is designed, and then an actual control law is constructed. By constructing the characteristic equation, the critical time delay threshold of the wave energy converter system is calculated. Lyapunov stability analysis proves that the system tracking error converges to a preset small neighborhood, thus completing the time-delay compensation control method for the wave energy converter. This invention can ensure that the critical time delay threshold of the system is always greater than the actual input time delay by adjusting the control parameters, guaranteeing system controllability.

The application discloses a kind of multi-span elastic supporting flow pipe stability parameter prediction method, it is related to flow pipeline vibration characteristic analysis technical field.By splitting the support position of multi-span pipeline into multiple independent pipe sections, vibration control equations describing each span pipeline are established respectively, the vibration control equations only consider the coupling effect of bending force, centrifugal force, gravity, coriolis force and inertia force of the pipeline, and do not contain any intermediate support constraint term;The intermediate support constraint is completely written into the inter-span coupling boundary condition, which avoids the defects of ambiguous meaning and difficult to converge in numerical calculation of traditional Dirac function method;By introducing dimensionless parameters to dimensionless the vibration differential equation, combined with the above elastic boundary and inter-span coupling constraint, the characteristic equation, characteristic function and eigenvalue under the complex boundary condition are derived, and the partial differential equation is converted into a system of ordinary differential equations after matrixization solution, and finally the accurate prediction value of natural frequency can be obtained.

The application provides a combined cycle single-extraction heat supply unit characteristic equation and power operation limit derivation method, obtains a gas turbine temperature correction coefficient, a gas turbine intake amount and a steam turbine extraction amount; obtains combined cycle power according to a first coefficient, a second coefficient and a third coefficient in a steam turbine power expression, a fourth coefficient, a fifth coefficient, a sixth coefficient, a seventh coefficient and an eighth coefficient in a gas turbine power expression and the gas turbine temperature correction coefficient; the application saves the number of field performance test working conditions of a gas-steam combined cycle single-extraction heat and power cogeneration unit, and is beneficial to relieving the phenomenon of excessive power generation of a heat and power unit, heat and power unit peak regulation difficulty and wind and light abandonment in grid peak regulation.

The application discloses a numerical prediction method for stability characteristic of a rough particle solid-liquid two-phase inner flow excited vertical lifting pipeline, and belongs to the technical field of deep-sea mining flow pipeline. In order to solve the technical problem that current numerical prediction of the stability of the flow pipeline generally only considers single-phase inner flow or gas-liquid two-phase flow, and it is difficult to effectively apply to the solid-liquid two-phase flow situation of deep-sea mining, the application adopts the slip velocity to describe the relationship between the movement speed of the solid particles in the vertical lifting pipeline and the flowing speed of the fluid in the pipeline, so as to determine the local concentration in the pipeline during stable conveying, and obtain the solid phase mass and the liquid phase mass per unit length in the pipeline during stable conveying; based on the modified Hamilton principle, a numerical prediction model for vibration of the vertical lifting pipeline under the excitation action of the solid-liquid two-phase flow is established; high-order partial differential equations which change with time and space are reduced to a series of ordinary differential equations which only contain time items; based on the eigenvalue method, a matrix eigenvalue equation is established, and the pipeline stability is determined by solving the eigenvalue.

The application discloses a kind of active front wheel steering time delay feedback controller parameter time delay feasible region's calibration method, and include steps: 1) the vehicle system model of active front wheel steering feedback controller including time delay is established;2) by constructing Lyapunov-Krasovskii functional, time delay independent stability parameter region is solved;3) by Laplace transform solving system characteristic equation, obtain stability discriminant polynomial;4) it is solved to the minimum critical time delay that can be tolerated under time delay independent stability region and time delay related stability zone under different control parameter combinations of system.This application can provide reference for controller stability design, compared with traditional active front wheel steering controller without considering time delay, can more effectively judge whether system meets stability requirement, and reduce control parameter adjustment range, so as to reduce test cost in actual engineering, guarantee the stability of vehicle control system.

This invention discloses a simplified method and system for tuning active disturbance rejection control (ADRC) for nuclear power steam generators with time delay. The method includes: establishing a mathematical model of the steam generator; designing a time-delay ADRC controller and equivalently transforming it into a two-degree-of-freedom structure to obtain the equivalent transfer function expression of the steam generator mathematical model and the characteristic equation of the closed-loop system; obtaining the characteristic equation of the closed-loop transfer function through low-frequency approximation, further obtaining the desired tracking speed parameter, and equivalently converting the adjustment of the outer-loop controller gain into the quantitative adjustment of the desired tracking speed parameter; simplifying the analysis of the parameters of the time-delay ADRC controller; and determining the relative time delay margin as a stability index through robustness index analysis to obtain the range of values ​​for the regularized observer bandwidth. This invention improves the mathematical analysis capabilities for modeling and controlling nuclear power equipment, making the TD-ADRC controller more practical in actual nuclear power equipment operation and ensuring the safe operation of nuclear power plants.

The present application relates to the technical field of composite structure dynamics analysis, and provides a method and system for predicting the natural frequency of a three-phase functionally graded composite conical plate, which comprises the following steps: calculating the equivalent parameters of a two-phase composite substrate containing GPL by using an improved Halpin-Tsai model, solving the equivalent parameters of a three-phase composite layer, constructing the nonlinear geometric relationship between the displacement field and the strain field, calculating the stiffness coefficient of each layer, constructing the kinetic energy of the three-phase composite conical plate, calculating the energy coefficient according to the stiffness coefficient of each layer, constructing the potential energy of the conical plate according to the energy coefficient, constructing the modal displacement function by using Chebyshev polynomials and boundary functions, establishing the characteristic equation based on the principle of minimum potential energy and solving it, and obtaining the natural frequency of the three-phase composite conical plate. The present application realizes efficient calculation of the natural frequency of the three-phase composite conical plate, and significantly improves the reliability and engineering application value of structural dynamics analysis.

The application discloses a kind of high-precision dynamic simulation-oriented mechanical inertia compensation method of electric vehicle test bench.This method introduces extended state observer in inertia compensator to replace traditional differential element, the total disturbance of system including acceleration dynamics and unmodeled dynamics is expanded to new state variable to carry out unified observation and compensation, solve the problem that high frequency noise amplification of test bench under high multiple compensation leads to the decline of speed simulation accuracy;The system closed-loop discrete mathematical model containing ESO is constructed, and the stability boundary of the system under high multiple compensation is determined using its characteristic equation and Jury criterion;In the stability domain, the sparrow search algorithm with working condition self-adaptive boundary early warning mechanism is used to optimize the observer gain, and the conflict between low-speed high-precision requirement and high-speed robustness requirement is solved.The application effectively solves the interference of high-frequency noise on the compensation loop, and realizes the high-precision and high-stability simulation of the mechanical dynamics of large inertia electric vehicle under all working conditions.

This invention discloses a method for predicting the dynamic response of a multi-span bridge under ship impact, comprising: discretizing the actual structure of the multi-span bridge into multiple mechanical elements based on the mechanical characteristics of the bridge, and determining the dynamic state input, output, and transmission paths of the multi-span bridge's mechanical system; constructing the dynamic state transmission equations of each mechanical element, and determining the overall transmission matrix of the multi-span bridge based on the transmission paths; determining the dynamic state characteristic equations of the multi-span bridge based on the overall transmission matrix and boundary conditions, and solving for the natural frequencies and corresponding state vectors of the multi-span bridge based on the characteristic equations; determining the overall dynamic equations of the multi-span bridge based on the ship impact force time history and the volume dynamic equations of each element; constructing the augmented characteristic vectors of the multi-span bridge based on the state vectors corresponding to the natural frequencies; and solving for the dynamic response of the multi-span bridge based on the augmented characteristic vectors and the overall dynamic equations.

The application discloses a kind of oil reservoir deep water drive front inversion methods based on natural potential dynamic response, belong to petroleum development engineering and geophysical monitoring technical field.The method first constructs the long-distance water drive oil physical simulation experiment of target reservoir, establishes the natural potential distribution of unimpinged area in front of water drive front in oil-water two-phase displacement process, and further reveals that the field strength gradient coefficient and intercept coefficient in the law follow the certain quadratic polynomial evolution characteristics with front position, and accordingly constructs generalized space-time evolution analytical model.In field application, real-time potential response is obtained using electrode array arranged on production well, and the monitoring data is substituted into the above-mentioned model to construct a quadratic characteristic equation about water drive front position, and the effective root is screened by solving the equation and combining reservoir physical boundary, to realize accurate positioning of deep water drive front.The application breaks through the limitation of existing technology, which depends on complex numerical simulation or only studies single-phase flow, and realizes quantitative inversion of "measuring single point to know far end" using clear physical field analytical solution, with the advantages of high calculation efficiency, high positioning accuracy and the like.

This invention discloses a disturbance estimation method for spacecraft systems with arbitrary suppression strength of measurement noise, belonging to the field of disturbance estimation technology for spacecraft systems. The method includes: Step 1: Establishing a nonlinear model of the spacecraft system considering measurement noise, using this model to accurately characterize the dynamic behavior of the spacecraft in complex environments; Step 2: Establishing a variable-order filter with independent parameters. The designed filter has the same cascaded structure as the observer, which makes the filter and observer parameters independent and uncoupled; Step 3: For the observer parameter adjustment problem, the method of undetermined coefficients is adopted. By solving the characteristic equation of the proposed filter's ESO and the characteristic equation of the desired pole placement, the coefficients of the two equations are compared to determine the observer parameters. In this method, the filter parameters increase with the filter order, and the sum of the observer parameters equals the observer order, avoiding the problem of over-parameterization and achieving arbitrary pole placement.

The application discloses a liquid tank sloshing semi-analytical solving method based on partition modal characteristic analysis, a medium and equipment, and belongs to the technical field of ship and ocean engineering. A liquid domain in a liquid tank is divided into a plurality of regular sub-regions, and an interface matching equation is constructed; a characteristic equation set is established, the characteristic equation set is converted into a generalized eigenvalue equation; scale balance preprocessing is performed, the preprocessed generalized eigenvalue equation is generated, and the preprocessed generalized eigenvalue equation is solved to obtain liquid natural frequency and liquid sloshing mode; according to the liquid sloshing mode and external excitation parameters, a free liquid surface wave height response time history is calculated; and a liquid tank sloshing response prediction result is output. The partition modal characteristic analysis method provided by the application adopts an analytical-numerical hybrid algorithm, and the calculation time is not affected by grid division; under the condition of ensuring sufficient calculation precision, the efficiency of a viscous flow solver is improved; and through scale balance preprocessing, the stability and precision of generalized eigenvalue solving are improved.

The present disclosure provides a method for obtaining fault coverage of a test algorithm and related equipment, and belongs to the technical field of semiconductor integrated circuit testing. The method comprises: obtaining a fault characteristic equation of a fault model of an object to be tested; obtaining an algorithm logic equation of a test algorithm; and determining whether the test algorithm covers the fault model according to the algorithm logic equation and the fault characteristic equation. The present disclosure provides a scheme for obtaining fault coverage of a test algorithm with low cost and high efficiency.

This invention discloses a GNSS noise identification method and system based on Riemannian manifold evolution and neural operators, belonging to the field of high-precision data processing for satellite navigation. The method first reconstructs the phase space of the GNSS coordinate sequence, using a manifold encoder to map it to the latent space of the Riemannian manifold to obtain the metric tensor. Second, it constructs a continuously evolving vector field controlled by a neural constant differential operator, and generates the eigenphysical evolution ideal trajectory through spatiotemporal integration. Subsequently, it introduces the Lie derivative operator to calculate the geometric deviation rate of the observation field along the ideal field evolution to strip away the physical signal, outputting a high-purity random noise manifold. Finally, it uses a Fourier neural operator to extract frequency domain features, fits the power spectral density, inputs a fully parameterized characteristic equation to calculate the significance coefficients, and dynamically outputs the optimal combined noise model. This invention overcomes the shortcomings of traditional methods that are sensitive to discrete sampling and missing data, achieving high-precision geometric decoupling of physical signals and random noise, and adaptive identification of complex noise.

The application relates to an algebraic operation phase-locked loop method, a converter controller and a grid-connected converter feasible region construction method. Compared with a traditional phase-locked loop, the algebraic operation phase-locked loop has better dynamic performance, and the order of the phase-locked loop can be reduced through algebraic operation, so that the stable operation feasible region of a system is conveniently constructed. The construction method is based on the algebraic operation phase-locked loop, a small signal model of a grid-connected converter and a controller thereof is derived, a system characteristic equation is solved based on a multiple-input multiple-output system theory, and a system stability condition is given. Based on the system stability condition, a construction method of a system stable feasible region is proposed. Compared with a traditional synchronous rotating coordinate system phase-locked loop, the algebraic operation phase-locked loop has faster response speed and better dynamic performance. Compared with a traditional parameter enumeration and repeated verification method, the grid-connected converter feasible region construction method based on the algebraic operation phase-locked loop is more simple and intuitive, and repeated analysis when parameters change is avoided.

The present application relates to a kind of space solar panel servo motor system rigid-flexible coupling modal modeling method, belong to spacecraft dynamics modeling technical field.This method aims to solve the failure of existing analytical model under single-axis large angle rotation and the problem that finite element model lacks explicit mathematical equation and is difficult to be directly used for control system design.The technical scheme is:establishing system geometry model and coordinate system;Adopting characteristic orthogonal polynomial to construct solar panel vibration displacement function;System kinetic energy, strain energy and hinge potential energy function are constructed;Based on Rayleigh-Ritz method, the system modal characteristic equation is established and the natural frequency and vibration mode are solved numerically.This method can realize the accurate modeling of single-axis large range rotation, and directly obtain low-dimensional high-precision explicit mathematical model, which is convenient for docking and co-simulation with control software.

The application discloses a kind of based on graph theory's water and electricity station water power generation system operation stability analysis method, this method is first based on the basic principle of graph theory, the whole system of water and electricity station is represented as the topological network formed by directed edge and node, and each node and each edge is numbered;Then according to the numbering of node and edge and water and electricity station system parameters, construct water and electricity station system overall frequency domain characteristic matrix C (s), establish characteristic equation det [C (s)]=0, and by solving eigenvalue s, with the real part of all eigenvalues is less than 0 as the basis for distinguishing stability.The method proposed by the application can conveniently realize the stability analysis general modeling of arbitrary hydraulic system topological structure, greatly facilitates the water and electricity station system operation stability analysis, provides a new way for in-depth analysis of different complex hydraulic topological water and electricity station free vibration characteristics and stability domain, and has wide application prospect.

The present disclosure relates to the technical field of compressor analysis, and particularly provides a method and device for evaluating the flow stability of a compressor under thermal shock distortion, the method comprising: constructing Euler equations of a compressor to be evaluated; obtaining small disturbance equations of the compressor based on small disturbance assumption and the Euler equations, and solving the small disturbance equations based on flow field data in a thermal shock process to obtain small disturbance solutions of the compressor, the small disturbance equations being determined based on an assumption that disturbance amplitude variation of small disturbance is consistent with thermal shock distortion disturbance variation or an assumption that thermal shock distortion disturbance is periodic disturbance; determining boundary conditions of blades in the compressor based on a disk model and parallel compressor theory, and determining a system stability characteristic equation of the compressor according to the boundary conditions and the small disturbance solutions; and determining a flow stability evaluation result of the compressor according to a solving result of the system stability characteristic equation. The present disclosure reduces the difficulty of evaluating the flow stability of the compressor under thermal shock distortion.