132 results about "Characteristic equation" patented technology

The invention provides a quality evaluation method of fresh corn. The quality evaluation method comprises the following steps: step 1, treating the fresh corn by adopting different blanching modes; step 2, selecting a plurality of evaluation indexes to respectively measure the fresh corns treated by different blanching modes; step 3, screening a variation coefficient gt; 15% of evaluation indexes are used as key quality indexes; step 4, carrying out data standardization processing on the screened key quality indexes; 5, performing principal component analysis on the key quality indexes by adopting SPSS data analysis software, and calculating the weighted variance contribution rate of each principal component; 6, calculating the coefficient of each key quality index; step 7, obtaining a characteristic equation of each principal component; and step 8, accumulating the product of the feature vector of each principal component in the blanching mode and the contribution rate of the weighted variance of the corresponding principal component to obtain the comprehensive quality score of the fresh corn in the blanching mode.

The invention discloses a multi-branch hydro-generator stator grounding fault active arc extinction method, which comprises the following steps: S1, constructing an analytic function of a double-frequency fault potential by using a neutral point and a generator end voltage after a generator fault and combining a winding connection sequence; s2, deriving a linear constraint relation between a third harmonic fault potential real part and an imaginary part; s3, according to the linear constraint relation, in combination with the potential expression of each branch winding of the third harmonic, constructing a target function for fault solution, and solving a solution set based on the third harmonic characteristic quantity; s4, according to the fundamental wave fault characteristic equation, constructing a fundamental wave difference coefficient multi-solution screening criterion, and obtaining a unique solution of the double-frequency fault potential; s5, aiming at the multi-branch hydro-generator, constructing a neutral point dual-frequency power supply injection amount calculation formula; and correctly adjusting the injection amount of the neutral point double-frequency controllable power supply by using the screened double-frequency fault potential unique solution, and suppressing the voltage of the fault point to be 0 to realize arc extinction. According to the invention, reliable arc extinction of the multi-branch hydraulic generator can be realized.

The invention relates to the technical field of physical acoustics, in particular to a saturated porous medium metasurface Portrait wave frequency dispersion relation calculation method and system, and the method comprises the following steps: obtaining expressions of solid skeleton displacement, fluid relative displacement, total stress, solid shear stress and pore pressure under the action of Portrait waves; obtaining an expression of a fluid displacement component and a fluid normal stress; obtaining an expression about the relative motion of the resonator; according to all the expressions, stress and displacement continuity boundary conditions are applied to the interface of the saturated porous medium and the fluid layer, a characteristic equation of frequency dispersion characteristics is obtained and solved, and a frequency dispersion curve is obtained. According to the method, the explicit frequency dispersion relation of the saturated porous medium metasurface portrait waves is provided, the calculation efficiency and prediction precision of complex interface wave propagation are improved, the optimal design of the metasurface resonator array can be guided, and a key theoretical tool and technical support are provided for design of high-performance acoustic functional devices and structures.

The invention discloses a design method of a pressure control throttle valve with the pressure drop linearly changing along with the stroke, and belongs to the technical field of automation of oil and gas exploitation equipment.The design method comprises the following steps that the linear relation between the pressure drop and the stroke of the throttle valve serves as a target; a mathematical model of a valve element contour is established by establishing a minimum throttling area equation of a cylindrical valve and a wedge-shaped valve, correcting a flow pressure drop characteristic equation and deducing a differential pressure linear adjustment equation, a valve element contour curve meeting the linear requirement is deduced through variable-diameter contour optimization design, and therefore the valve element structure of the throttling valve is obtained. By means of the design method, the valve element contour curve with the wider linearity range of pressure control adjustment and the better precision can be obtained, and the design method is more efficient and universal.

The invention discloses an ocean vortex three-dimensional flow field reconstruction method based on physical constraints, and belongs to the technical field of physical oceanography and data modeling, and the method comprises the steps: calculating sea surface height abnormal data according to climate state data and sea surface observation data, recognizing vortex features, and dividing a vortex into grid points; according to the climate state data and the vortex vertical mode characteristic equation, constructing a vortex vertical mode function, and obtaining a vortex horizontal flow velocity vertical structure function; by taking the sea surface flow velocity abnormal condition and the deep layer flow velocity abnormal condition as constraints, determining a vortex vertical modal coefficient according to a vortex horizontal flow velocity vertical structure function, and reconstructing a vortex horizontal flow velocity vertical structure at each grid point; and superposing the vortex horizontal flow velocity vertical structure and the climate state horizontal flow velocity vertical structure to obtain a seawater horizontal flow velocity vertical structure to construct a vortex three-dimensional flow field structure. The problems that the prior art is limited to the sea surface, and the vertical structure of the vortex is difficult to accurately describe are solved.

The invention relates to a calculation method and system for a non-load structural design value of the early temperature of a wall, and belongs to the technical field of construction control. The calculation method comprises the steps that geometric parameters, material parameters, environmental parameters and hydration heat parameters of a concrete continuous wall are obtained; according to the material parameters, a thermal diffusion coefficient is calculated, and a heat production rate function changing along with time is generated; based on the geometric parameters, the material parameters and the environmental parameters, calculating a Pitot number, and defining dimensionless coordinates and dimensionless time; solving the characteristic equation according to the Pitot number to obtain a characteristic value sequence and a corresponding vibration mode function sequence; calculating a weight coefficient of each mode based on the initial temperature distribution and the vibration mode function sequence; and solving a time domain ordinary differential equation and applying convolution integration, generating a time-varying modal amplitude function sequence, synthesizing a dimensionless temperature field, determining a convergence solution through a truncated modal number, and converting the dimensionless temperature field into a physical temperature field for output. The early temperature gradient distribution rule of the wall can be accurately captured.

The invention discloses a parameter setting method and device for a grid-connected double-fed wind power plant, and the method comprises the steps: building a full-order linear state space model based on the interaction behaviors of N fans in the grid-connected double-fed wind power plant and a power grid, and N is a positive integer; performing equivalent order reduction processing on the basis of the full-order linearization state space model to obtain N independent single grid-connected doubly-fed fan equivalent subsystem models; according to the N mutually independent single grid-connected doubly-fed fan equivalent subsystem models, constructing a dynamic characteristic equation of a grid-connected doubly-fed wind power plant under a direct-current voltage control time scale; and performing stability judgment on the dynamic characteristic equation of the grid-connected double-fed wind power plant to obtain the parameter setting method suitable for the grid-connected double-fed wind power plant under the slow time scale. According to the method, the analysis calculation amount is effectively reduced, the efficiency and feasibility of small-interference stability analysis of the wind power plant are remarkably improved, and complex large-scale wind power plant analysis is more efficient.

The invention relates to the technical field of composite material structure dynamics analysis, and provides a method and system for predicting the inherent frequency of a three-phase functionally graded composite material conical plate, and the method comprises the steps: employing an improved Halpin-Tsai model to calculate the equivalent parameters of a GPL-containing two-phase composite matrix, solving the equivalent parameters of a three-phase composite layer, and calculating the inherent frequency of the three-phase composite material conical plate. The method comprises the following steps: constructing a nonlinear geometrical relationship between a displacement field and a strain field, calculating a stiffness coefficient of each layer, constructing kinetic energy of the three-phase composite material conical plate, calculating an energy coefficient according to the stiffness coefficient of each layer, constructing potential energy of the conical plate according to the energy coefficient, and constructing a modal displacement function by adopting a Chebyshev polynomial and a boundary function. And establishing a characteristic equation based on a minimum potential energy principle and solving to obtain the inherent frequency of the three-phase composite material conical plate. According to the method, efficient calculation of the inherent frequency of the three-phase composite material conical plate is achieved, and the reliability and engineering application value of structural dynamics analysis are remarkably improved.

The invention discloses a critical parameter prediction method for a vertical cantilever fluid conveying pipe comprising a water injection pump and a Y-shaped nozzle, and relates to the field of fluid conveying pipe critical parameter calculation. The prediction method is based on an Euler-Bernoulli beam model and a momentum theorem, bending force, centrifugal force, Coriolis force, inertia force, gravity and additional force generated by an elbow are comprehensively considered, and an oscillatory differential equation of the fluid conveying pipe is established. The method comprises the following steps: performing dimensionless processing on an oscillatory differential equation by introducing dimensionless parameters, deducing a characteristic equation, a characteristic function and a characteristic value under a cantilever boundary condition, converting a partial differential equation into an ordinary differential equation set, and performing matrix solution; and finally, accurate prediction values of the critical flow velocity and the critical frequency can be obtained. The method can effectively reflect the influence rule of the nozzle and the concentrated mass on the vibration characteristics of the fluid conveying pipe, and realizes the accurate prediction of the critical parameters of the vertical cantilever containing the concentrated mass belt Y-shaped nozzle fluid conveying pipe.

The invention belongs to the technical field of power system stability analysis and control, and relates to a wind power plant characteristic root rapid solving method and system based on the circular ring theorem, and the method comprises the following steps: S1, carrying out the online identification of impedance; s2, constructing a wind power plant grid-connected system characteristic equation; s3, establishing a circular ring theorem model; s4, analyzing the stability of the wind power plant grid-connected system; according to the technical scheme, the calculation method of the circular ring theorem is adopted, the order number of the wind power plant grid-connected system does not need to be reduced, the feature root of the high-order wind power plant grid-connected system can be rapidly calculated, the solving efficiency is high, meanwhile, the directional capturing capacity of the main feature root is high, and the main feature root of the wind power plant grid-connected system can be rapidly searched.

The invention relates to an ultrasonic guided wave modal analysis method, device and equipment in a fluid saturated porous medium and a computer readable storage medium, and the method comprises the steps: determining a fluctuation control equation in a solid-fluid coupled porous medium domain; describing a conversion relation between the particle displacement of any position in the porous medium domain and the particle displacement of the corresponding section through a wave number and an angular frequency, and converting the fluctuation control equation in the solid-fluid coupled porous medium domain into a characteristic value solving form based on the conversion relation to obtain a characteristic equation; after specific boundary conditions are applied to the boundary of the porous medium, numerical solution is carried out on the characteristic equation; and according to a feature solving result, generating a modal analysis result of the ultrasonic guided wave. The technical scheme disclosed by the invention is particularly suitable for modal analysis of ultrasonic guided waves in a fluid saturated porous medium with an irregular section.

The invention relates to the technical field of ultrasonic guided wave nondestructive testing, and particularly discloses an arched concrete filled steel tube bridge detection method based on ultrasonic guided wave frequency dispersion characteristics, which adopts a theoretical derivation-simulation verification-experimental analysis method, and comprises the following steps: firstly, establishing a fluctuation characteristic equation based on a rotating coordinate system and a semi-analytical finite element method; deriving a guided wave frequency dispersion equation, obtaining a frequency dispersion curve through numerical calculation, and determining an optimal monitoring mode and an excitation frequency range; a three-dimensional finite element model is constructed for wave field numerical simulation, and the reliability of the model is verified through comparison of a theoretical solution and a simulation solution; then carrying out an ultrasonic guided wave detection experiment, collecting a time domain signal and extracting an actually measured frequency dispersion characteristic; and finally establishing theoretical prediction through time-frequency analysis, comparing numerical simulation with experimental data, and verifying the accuracy of a theoretical model in combination with error analysis. The method can accurately detect the defects of the arched concrete-filled steel tube bridge, and improves the reliability and practicability of complex structure damage identification.

The invention discloses a photovoltaic power generation capacity credibility evaluation method based on joint probability modeling and a random process, and the method comprises the steps: collecting historical irradiance and temperature data of a target region, extracting an hour-level mean value and a standard deviation of the historical irradiance and temperature data, and dividing a seasonal data set; a Copula function is adopted to construct a joint probability distribution model of irradiance and temperature, a Gumbel Copula function is selected in summer, and a Clayton Copula function is selected in winter; generating a random fluctuation sequence of irradiance and temperature based on a stochastic differential equation, and calculating photovoltaic real-time output by combining a photovoltaic cell characteristic equation; a double-state Markov model is adopted to simulate traditional unit faults and load fluctuation, and system loss of load expectation (LOLE) is quantified through Monte Carlo simulation; carrying out dynamic iteration by utilizing an equivalent conventional capacity method (ECP), and calculating the capacity credibility of photovoltaic power generation; according to the invention, a reliability evaluation basis is provided for high-proportion photovoltaic grid-connected planning.

The application relates to the field of circuit state space equation solving technology in the real-time simulation field, and discloses a state space equation discretization method for capacitor and inductor element characteristics, which comprises the following steps: A) establishing a state space differential equation of a circuit; B) establishing a characteristic equation of a capacitor and an inductor element, determining a numerical integration method used by each capacitor and inductor element in the circuit, and obtaining a discrete time domain characteristic equation by using the numerical integration method; C) combining the discrete time domain characteristic equation of step B) and the state space differential equation of step A) to obtain a state space discrete equation of the circuit; and D) cyclic simulation. The state space equation discretization method for capacitor and inductor element characteristics improves the speed and precision of real-time simulation of a circuit system by independently discretizing the characteristic equations of each capacitor and inductor element and optimizing the discretization process of the state space equation.

The invention relates to the technical field of electromagnetism, in particular to a multi-layer slab waveguide mode processing method, device, equipment, medium and program, and the method comprises the steps: constructing a transfer matrix model of a multi-layer slab waveguide; obtaining boundary conditions of the infinite space, and determining a corresponding real number domain characteristic equation and a complex number domain characteristic equation according to the transfer matrix model and the boundary conditions so as to determine a guided mode and a leakage mode of the multilayer slab waveguide in the infinite space; introducing a perfect matching layer to convert a radiation condition of an infinite space into an absorption boundary in a finite computational domain, constructing a finite space characteristic equation according to the thicknesses of the perfect matching layer and the absorption boundary, and positioning a plurality of correction leakage modes according to the finite space characteristic equation to generate a Bereger mode; and generating complete mode distribution according to the guided mode, the leakage mode and the Bereger mode. Therefore, the problems of relatively poor calculation precision, relatively slow calculation speed, limitation of complete mode solving in the multilayer slab waveguide and the like in related technologies are solved.

The invention discloses an electric vehicle experiment table mechanical inertia compensation method for high-precision dynamic simulation. According to the method, an expansion state observer is introduced into an inertia compensator to replace a traditional differential link, system total disturbance including acceleration dynamics and unmodeled dynamics is expanded into new state variables for unified observation and compensation, and the problem that the rotation speed simulation precision is reduced due to high-frequency noise amplification of an experiment table under high-multiple compensation is solved; constructing a system closed-loop discrete mathematical model containing ESO, and determining a stability boundary of the system under high-multiple compensation by using a characteristic equation of the system closed-loop discrete mathematical model and a Jure criterion; a sparrow search algorithm with a working condition adaptive boundary early warning mechanism is adopted in a stable domain to optimize observer gain, and the conflict between the low-speed and high-precision requirement and the high-speed and high-robustness requirement is solved. According to the invention, the interference of high-frequency noise on a compensation loop is effectively solved, and high-precision and high-stability simulation of the mechanical dynamic state of the large-inertia electric vehicle under all working conditions is realized.

The invention discloses a spacecraft system disturbance estimation method with random suppression intensity of measured noise, which belongs to the technical field of disturbance estimation of spacecraft systems, and comprises the following steps of: 1, establishing a nonlinear model of a spacecraft system considering the measured noise, and accurately representing the dynamic behavior of a spacecraft in a complex environment by using the model; 2, a variable-order filter with independent parameters is established, the designed filter has the same cascade structure as the observer, and therefore the parameters of the filter and the observer are mutually independent and not coupled; and step 3, aiming at an observer parameter adjustment problem, adopting an undetermined coefficient method, solving a proposed ESO characteristic equation of filtering and a characteristic equation of an expected configured pole, carrying out coefficient comparison on the two equations, and determining an observer parameter. According to the method, the parameters of the filter are increased along with the increase of the order of the filter, and the sum of the parameters of the observer is equal to the order of the observer, so that the problem of excessive parameterization is avoided, and arbitrary pole assignment is realized.

The invention discloses a parameter estimation and adaptive control method, device, medium and product of a high-performance aircraft pitch angular velocity control system with stability margin self-configuration, and relates to the field of aircraft control, the method comprises the following steps: collecting the pitch angular velocity of an aircraft and the deflection angle of an elevator in real time, and calculating a tracking error; constructing a relation equation of system parameters and stability margin based on a PI controller, and performing approximate simplification by adopting a numerical approximation method; estimating system parameters and time delay on line by adopting an approximate nonlinear least square algorithm; and substituting the target stability margin, the system parameter estimation value and the time delay estimation value into a system frequency domain characteristic equation for solving to obtain a proportional gain and an integral time constant of a PI controller, and adjusting an elevator deflection angle of the aircraft in combination with a tracking error so as to control the pitch angular velocity of the aircraft. According to the invention, the autonomous configuration of the stability margin is realized, and the stability, robustness and dynamic adaptation capability of the control system are improved.

The invention provides a vibration modal analysis method for a large-span cable-stayed bridge, and belongs to the technical field of bridge engineering, the cable-stayed bridge is simplified into a multi-cable cable-stayed beam structure considering the influence of cable force, and a cable-stayed bridge dynamic model is constructed through a parameterized order reduction technology; deducing a frequency characteristic equation of the cable-stayed bridge by combining a transfer matrix method and boundary conditions of the cable-stayed bridge; by solving the characteristic equation, the inherent frequency and modal characteristics can be determined more accurately and quickly; according to the method, the technical bottleneck of insufficient calculation efficiency of a traditional finite element method is innovatively solved, and fine evaluation of the fundamental frequency and the dynamic characteristics of the large-span cable-stayed bridge is completed; the method has both theoretical preciseness and engineering practicability, the calculation efficiency is remarkably improved, a new technical means is provided for dynamic performance evaluation of the kilometer-scale cable-stayed bridge, and the method has important engineering application value.

The application provides a control method and a control system of a steer-by-wire system. The method comprises the following steps: constructing a steering system dynamics equation based on a target front wheel running parameter, a configuration parameter and a target damping coefficient of a magneto-rheological damper in a shimmy instability mode, wherein the product of the target damping coefficient and a front wheel rotation speed is equal to the product of an initial damping coefficient of the magneto-rheological damper and a magneto-rheological damper current; obtaining a characteristic equation and all characteristic value expressions based on the steering system dynamics equation; obtaining real-time values of the target front wheel running parameter, a value of the configuration parameter, a magneto-rheological damper current real-time value and a value of the initial damping coefficient; obtaining real part values of all characteristic values of the characteristic value expressions based on the obtained values; and adjusting the magneto-rheological damper current real-time value until the real part values of all characteristic values are not greater than zero to obtain a value of the target damping coefficient, if there is at least one characteristic value whose real part value is greater than zero. The method according to the application can solve the front wheel shimmy problem.

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.

The invention discloses a steady-state fault electrical quantity calculation method containing a virtual synchronous machine control converter system, and belongs to the technical field of new energy power generation system control protection. The method comprises the following steps: determining a fault condition set and system parameters of a system; forming a node voltage equation, a power supply characteristic equation and a fault boundary condition of the fault network according to the fault condition and the system parameter; a trust-region-dogleg algorithm is adopted for simultaneous solution, and an adaptive virtual impedance value is obtained; judging whether the self-adaptive virtual impedance value is smaller than a set minimum virtual impedance value or not so as to determine the operation state of the converter; solving a current vector according to the operation state and the node voltage vector; and traversing the fault condition set to complete all calculations. According to the method, the technical problem that the adaptive virtual impedance of the virtual synchronous machine control converter in the fault ride-through state is unpredictable is solved, and accurate calculation of the steady-state fault electrical quantity of the virtual synchronous machine-containing converter system is realized.

The embodiment of the invention provides a multi-motor control method and device for a seat, electronic equipment and a storage medium. The method comprises the following steps: constructing a dynamic characteristic equation of a multi-motor system of a seat based on current running data of a vehicle and body shape information of a passenger on the seat; the multi-motor system comprises a plurality of motors; for each motor, determining a plurality of candidate set point sequences of the motor based on the dynamic characteristic equation of the motor; determining the comprehensive fitness of the plurality of candidate set point sequences of the motor, and determining a target set point sequence in the plurality of candidate set point sequences according to the comprehensive fitness; the target set point sequence comprises a target rotating speed and a target position of the motor; and controlling the multi-motor system according to the target rotating speeds and the target positions of the plurality of motors. The method is used for cooperatively controlling a multi-motor system of the seat in a self-adaptive manner according to an actual application scene, so that the adjustment of the seat conforms to the actual application scene.

The invention relates to the technical field of gas compressor analysis, and particularly provides a gas compressor flow stability evaluation and analysis method and device under circumferential distortion, and the method comprises the steps: constructing an Euler control equation of a to-be-evaluated gas compressor; obtaining a small disturbance equation of the gas compressor based on a small disturbance hypothesis and the Euler control equation, and solving the small disturbance equation based on the flow field data at the plurality of circumferential points to obtain a small disturbance solution of the gas compressor; determining boundary conditions of blades in the gas compressor based on an excitation disc model and a parallel gas compressor theory, and determining a system stability characteristic equation of the gas compressor under the condition of non-uniform circumferential flow field according to the boundary conditions and a small disturbance solution; determining a flow stability evaluation result of the gas compressor according to a solving result of the system stability characteristic equation; the accuracy of the flow stability evaluation result of the high-load gas compressor with the uneven circumferential flow field can be improved.

The application relates to the technical field and discloses a method and system for measuring and calculating apparent resistivity of horizontally layered earth, wherein a characteristic equation of horizontally layered earth is constructed according to an integral variable set obtained through an exponential discrete sampling method and horizontally layered earth parameters; an uplink electromagnetic wave amplitude kernel function of the characteristic equation at each integral variable is calculated to obtain an integral upper limit of horizontally layered earth, and the integral upper limit of horizontally layered earth is set as the maximum value of the integral variable satisfying a preset criterion; based on the integral upper limit of horizontally layered earth, the integral range of the constructed apparent resistivity relationship formula of an unbounded domain is limited to obtain an apparent resistivity relationship formula of a bounded domain; and based on a 151-point Gauss-Legendre integral algorithm and Euler transformation, the apparent resistivity relationship formula of the bounded domain is iteratively solved to obtain a measurement and calculation result of the apparent resistivity. The method meets the dual requirements of precision and efficiency for the measurement and calculation of the apparent resistivity of horizontally layered earth.

The invention discloses a single-mode guided wave defect detection method and system for an underwater water filling pipeline. The method comprises the following steps: establishing an SAFE-PML wave equation of guided waves in the underwater water filling pipeline; converting the SAFE-PML wave equation into a guided wave characteristic equation, and constructing an expression of guided wave mode energy; establishing a mapping relation between the guided wave modal amplitude and the axial length of the piezoelectric transducer by using modal extension; solving and extracting excitation characteristics of a guided wave mode through a guided wave characteristic equation; parameters of the piezoelectric transducer are optimized according to guided wave excitation characteristics, guided wave signals are collected, the occurrence time of defect signals in the guided wave signals is obtained, and defect detection is conducted on the whole underwater water filling pipeline through a guided wave reflection method. According to the invention, guided wave mode single excitation and defect detection of the underwater water filling pipeline are realized.

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 circumferential distortion, the method comprising: constructing Euler control equations of a compressor to be evaluated; obtaining small perturbation equations of the compressor based on small perturbation assumption and the Euler control equations, and solving the small perturbation equations based on flow field data at multiple circumferential points to obtain small perturbation solutions of the compressor; determining boundary conditions of blades in the compressor based on a cascade model and parallel compressor theory, and determining a system stability characteristic equation of the compressor under circumferential flow field unevenness according to the boundary conditions and the small perturbation 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 can improve the accuracy of the flow stability evaluation result of a high-load compressor with circumferential flow field unevenness.

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.

The invention discloses a condensate water supply system flow measurement method and device oriented to edge calculation, and the method comprises the following steps: S1, extracting multiple sets of pump set operation parameters under typical working conditions based on an industrial Internet platform historical database; s2, performing simulation modeling on the condensate water supply system, and constructing a nonlinear mapping relation between a pipeline resistance coefficient and flow by combining a pipeline geometric configuration, fluid physical property parameters and pump mechanical characteristics to obtain a pipeline resistance equation; s3, the pipeline resistance equation and the centrifugal pump lift flow characteristic equation are combined, an equation set is solved through a Newton-Raphson iteration method, and a theoretical calculation flow value is obtained; and S4, comparing the theoretical calculation flow value with the real-time measurement flow value, and dynamically adjusting model parameters to ensure that a model error is smaller than a set threshold value. The method has the effect of high flow measurement precision of the condensate water supply system.