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97 results about "Characteristic equation" patented technology
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In mathematics, the characteristic equation (or auxiliary equation) is an algebraic equation of degree n upon which depends the solution of a given nth-order differential equation or difference equation. The characteristic equation can only be formed when the differential or difference equation is linear and homogeneous, and has constant coefficients. Such a differential equation, with y as the dependent variable, superscript (n) denoting nᵗʰ-derivative, and aₙ, aₙ ₋ ₁, ..., a₁, a₀ as constants, aₙy⁽ⁿ⁾+aₙ₋₁y⁽ⁿ⁻¹⁾+⋯+a₁yʼ+a₀y=0, will have a characteristic equation of the form aₙrⁿ+aₙ₋₁rⁿ⁻¹+⋯+a₁r+a₀=0 whose solutions r₁, r₂, ..., rₙ are the roots from which the general solution can be formed.
Method for determining a fluid flow rate with a fluid control valve
InactiveCN103307342ALow costRealize the adjustment functionOperating means/releasing devices for valvesVolume/mass flow by electric/magnetic effectsFluid controlValve actuator
A method for determining a fluid flow rate with a fluid control valve utilizes inherent characteristics of a particular valve in conjunction with easily measured parameters in order to determine a flow rate through the valve. A valve flow characteristic equation, a flow coefficient, and a rangeability for the valve are known and hardcoded into a chipset that controls the valve. A differential pressure transducer measures the pressure drop across the valve. A valve actuator controls the valve opening fraction. The differential pressure transducer and the valve actuator provide feedback signals to the chipset. The known and measured parameters are used to calculate an instantaneous valve characteristic and a fully-open flow rate for the valve. The instantaneous flow rate through the valve is then calculated from the instantaneous valve characteristic and the fully-open flow rate.
Owner:冯经娟
Double-fed grid-connected system subsynchronous oscillation analysis method by considering frequency coupling effect
ActiveCN111525611ASingle network parallel feeding arrangementsPower oscillations reduction/preventionFrequency couplingHarmonic linearization
The invention relates to a double-fed grid-connected system subsynchronous oscillation analysis method by considering a frequency coupling effect. The method comprises the following steps of: firstly,inputting the fan parameter, the operation state and the grid-connected parameter of the doubly-fed grid-connected system; and establishing a doubly-fed fan external impedance analytical model basedon a harmonic linearization method. The method is mainly characterized in that the frequency coupling effect of output harmonic current of the doubly-fed fan under single-frequency harmonic voltage disturbance is considered, and meanwhile, according to two operating states of the doubly-fed fan, the external impedance analytical model of the fan is derived under different operating states; a polecriterion expression suitable for the characteristic equation of the doubly-fed grid-connected system is given in combination with grid-connected parameters; and finally, the subsynchronous oscillation stability of the target is judged system according to the calculated poles of the system characteristic equation. The subsynchronous oscillation mechanism of the doubly-fed grid-connected system isdisclosed quantitatively, and the subsynchronous oscillation stability of the target doubly-fed grid-connected system can be quantitatively analyzed.
Owner:XIAN THERMAL POWER RES INST CO LTD +1
Experiment device and method for measuring uniform load performance of power dividing gear system
ActiveCN104280237AEliminates the effects of friction torqueLow costMachine gearing/transmission testingGear systemEngineering
The invention provides an experiment device and method for measuring uniform load performance of a power dividing gear system. The power dividing gear system is erected, step-by-step loading is carried out on a single branch circuit, friction coefficients of the branch circuits are determined, the relation between output strain of the branch circuits and torque of a duplicate gear shaft is calibrated, uniform load coefficients of the branch circuits under different input torques are calculated, and a uniform load characteristic equation of the power dividing gear system is obtained. According to the experiment device and method, the defects that an existing uniform load performance experiment testing device has high requirements for erecting of a test table, needs to exert dynamic loads on a gearbox, and is high in experiment cost and long in period are overcome, and the experiment device and method for measuring the uniform load performance of the power dividing gear system are provided, wherein implementation is simple and easy, only static loads need to be exerted, the cost is low, and the experiment period is short.
Owner:NORTHWESTERN POLYTECHNICAL UNIV
Heat supply pipe network hydraulic calculation method based on big data analysis technology
PendingCN112560240AHydraulic stabilityImprove operational efficiencyData processing applicationsDesign optimisation/simulationNetwork topologySystem topology
The invention provides a heat supply pipe network hydraulic calculation method based on a big data analysis technology, and the method comprises the following steps: 1, building a heat supply pipe network system topology; 2, building a digital twinning relation: 201, building a pipeline characteristic equation, 202, building a transmission and distribution analysis model, 203, building a regulation and control equipment characteristic model, 204, establishing a hydraulic joint debugging model based on big data: simultaneously establishing a topological relation, a transmission and distributionanalysis model and a regulation and control equipment characteristic model in the topological graph of the heat supply pipe network system, setting an operation boundary condition and a big data analysis mode, and establishing a hydraulic joint debugging model; 3, performing operation simulation based on a digital twinning relationship; 4, performing data iterative analysis. According to the method, a passive adjustment mode of a traditional urban heat supply pipe network system is converted into active adjustment, a favorable basis is provided, the hydraulic working condition stability of the system is improved, and the operation efficiency is improved.
Owner:上海全应科技有限公司
AC-DC hybrid microgrid droop coefficient selection method based on power flow feasible region
PendingCN111355241AHigh speedImprove computing efficiencySingle network parallel feeding arrangementsAc networks with different sources same frequencyMicrogridPower flow
The invention provides an AC / DC hybrid microgrid droop coefficient selection method based on a power flow feasible region. The method comprises the steps of S1, establishing an AC / DC hybrid microgridunified power flow calculation model; s2, on the basis of the AC-DC hybrid microgrid unified power flow calculation model established in the S1, calculating a power flow feasible region containing a droop coefficient; s3, based on the power flow feasible region obtained in S2, establishing a boundary convex-concave characteristic equation of the power flow feasible region, and obtaining a power flow feasible region approximate boundary containing a droop coefficient; and S4, based on the approximate boundary of the power flow feasible region obtained in the S3, selecting a droop coefficient enabling the AC-DC hybrid microgrid to operate stably. Meanwhile, the invention provides a terminal for executing the method. According to the method, the speed of solving the voltage stability criticalpoint is greatly improved, and the calculation efficiency is high; by deriving a boundary convex-concave characteristic equation of a high-dimensional power flow feasible region, the value range accuracy of the droop coefficient is improved; and a reference is provided for stable operation of the AC-DC hybrid microgrid.
Owner:SHANGHAI JIAO TONG UNIV +3
City power distribution network superconducting cable application scheme comparison and selection method based on analytic hierarchy process
PendingCN111898284AMake up for the subjectivity of evaluation resultsData processing applicationsDesign optimisation/simulationEvaluation resultMaximum eigenvalue
The invention discloses a city power distribution network superconducting cable application scheme comparison and selection method based on an analytic hierarchy process. The method comprises the following steps: firstly, classifying, investigating and collecting investment cost, power supply resource requirements and benefit factors involved in a superconducting cable scheme, and performing modeling calculation; secondly, carrying out normalization processing on the comprehensive evaluation result of the non-quantizable factors; thirdly, calculating a comprehensive evaluation result corresponding to the scheme through result multiplication and accumulation according to different factors and indexes subjected to corresponding weight normalization, and taking the scheme with the maximum result as a comparison and selection recommendation scheme; establishing a scheme evaluation element judgment matrix; checking the consistency of the scheme evaluation element judgment matrix, and determining an evaluation weight; and finally, solving a characteristic equation about the scheme evaluation element judgment matrix to obtain each factor corresponding to the maximum characteristic value lambda max and a corresponding weight. According to the superconducting cable planning scheme comparison and selection model for quantifying multiple factors of cost and benefit, the defects of existing subjective evaluation are overcome.
Owner:SHANGHAI ELECTRIC POWER DESIGN INST
Method and system for measuring natural vibration frequency and vibration mode for building structure dynamic analysis
PendingCN111709073AImprove stabilityGuaranteed stabilityGeometric CADCharacter and pattern recognitionCharacteristic equationControl theory
The invention belongs to the technical field of civil engineering, and discloses a method and a system for measuring natural vibration frequency and vibration mode for dynamic analysis of a building structure. The method for measuring the natural vibration frequency and the vibration mode for building structure dynamic analysis comprises the following steps: for a selected building, establishing an equation of multi-degree-of-freedom undamped free vibration during undamped autonomous vibration of a multi-degree-of-freedom building structure system, and converting the equation into a characteristic equation of a motion equation; supposing that a characteristic equation of the motion equation obtained by conversion has a non-zero solution and a coefficient determinant is zero, and obtaininga frequency equation; substituting the corresponding natural vibration frequency into a characteristic equation of the motion equation to obtain a vibration mode; and carrying out vibration mode normalization. According to the method, an equation of multi-degree-of-freedom undamped free vibration is converted into a characteristic equation of a motion equation, so that the calculated amount is simplified, and the algorithm stability is improved; by simplifying the characteristic equation of the motion equation, the calculation amount is reduced, the calculation efficiency is improved under thecondition of ensuring the stability, and the calculation time is saved.
Owner:HUANGHUAI UNIV +1
Heat supply network waterway modeling method for comprehensive energy system scheduling
ActiveCN111414721AImprove applicabilityContribute to unified schedulingGeometric CADDesign optimisation/simulationIntegrated energy systemStream flow
The invention relates to a heat supply network waterway modeling method for comprehensive energy system scheduling, and belongs to the technical field of operation control of comprehensive energy systems. According to the method, a hydraulic analysis model and a power network model are unified, and a relationship between a hydraulic dynamic state and a hydraulic steady state is established. The method is based on characteristic equations of a heat distribution pipeline, a flow control valve and a booster pump. The method comprises: abstracting waterway element models such as water resistance,water inductance and a water pressure source, establishing hydraulic branch characteristics of a heat supply network based on the waterway elements, establishing hydraulic topology constraints of theheat supply network based on Kirchhoff-like voltage and current laws, and finally establishing a steady-state hydraulic network equation by combining the hydraulic branch characteristics and the hydraulic topology constraints. The method is clear in physical significance, covers various devices such as a heat distribution pipeline, a flow control valve and a booster pump, comprehensively considersheat supply network branch characteristics and topological constraints, is high in modeling method applicability, and facilitates unified scheduling of a heat heterogeneous energy flow system and anelectricity heterogeneous energy flow system.
Owner:TSINGHUA UNIV
Optimization method for optimal robust fractional order PI<lambda>D controller of time delay system
ActiveCN111443600ASatisfy the frequency domain specificationImprove robustnessControllers with particular characteristicsAutomatic controlFractional-order control
The invention belongs to the related technical field of automatic control, and discloses an optimization method of an optimal robust fractional order PI<lambda>D controller of a time delay system. Themethod comprises the following steps: (a) constructing a closed-loop transfer function of a to-be-optimized control system; (b) obtaining a characteristic equation of the closed-loop transfer function relative to unknown parameters in the PI<lambda>D controller; and (c) constructing constraint conditions required to be met by a to-be-optimized first-order inertia delay control system, and determining a value range of an unknown parameter in the PI<lambda>D controller by utilizing the characteristic equation, and solving and obtaining a value of the unknown parameter in the PI<lambda>D controller according to the constraint condition and the value range so as to determine the PI<lambda>D controller, thereby realizing an optimization process. According to the invention, optimization of thePI<lambda>D controller is realized, and thus the control system has strong robustness and optimal dynamic performance.
Owner:HUAZHONG UNIV OF SCI & TECH
Single-material structure topological optimization method and system considering structural stability
PendingCN113191040AThe optimization result is clearObvious branchDesign optimisation/simulationSpecial data processing applicationsAlgorithmStructural engineering
The invention discloses a single-material structure topological optimization method and system considering structure stability, and belongs to the field of structure topological optimization. The method includes the following steps: constructing an optimization model which takes an expansion coefficient as a design variable, takes structure total flexibility minimization as a target and takes volume and buckling load factors as constraint conditions; calculating the total flexibility, volume and buckling load factor of the structure under the current expansion coefficient and the level set function; calculating a new expansion coefficient, and interpolating a new level set function; determining whether the difference between the current expansion coefficient and the reference value is smaller than a threshold value, if so, ending optimization, and determining the structure topology according to the current level set function; otherwise, continuing to optimize. Buckling load factor constraints based on expansion coefficients are introduced, the expansion coefficients are interpolated to obtain a level set function, the level set function determines pseudo-density, the pseudo-density determines a geometric stiffness matrix and a stiffness matrix, buckling load factors are solved through a characteristic equation, and the expansion coefficients influence the buckling load factors; therefore, the stability is considered, the optimization result is clearer, and the branches are more obvious.
Owner:HUAZHONG UNIV OF SCI & TECH
Simple calculation method for variable working condition performance of steam extraction heat supply type gas-steam combined cycle unit
InactiveCN110807261AAvoid the problem of lack of unit performance dataCalculation method is simpleDesign optimisation/simulationGas compressorProcess engineering
The invention discloses a simple calculation method for variable working condition performance of a steam extraction heat supply type gas-steam combined cycle unit. The method comprises. The method comprises the following steps: building a gas cycle variable working condition model of the combined cycle unit, and calculating gas parameters under variable working conditions according to the gas cycle variable working condition model; correcting gas parameters under variable working conditions; and calculating variable working condition output parameters of the combined cycle unit. According tothe invention, a data and mechanism combined modeling mode is adopted; a component characteristic equation derived from experimental rules and theories is used as a basis; fitting the key parameters and the key coefficients of the equation by utilizing past data of the unit; the application range of the model is widened; the problems that a gas compressor and a gas turbine in gas circulation are difficult to model due to the fact that manufacturers keep performance data secret, and the modeling process of a waste heat boiler is complex are effectively solved. Simple calculation of the variableworking condition performance of the gas-steam combined cycle unit considering universality and high precision is achieved, and an effective means is provided for variable working condition characteristic analysis of the combined cycle unit.
Owner:JIANGSU FRONTIER ELECTRIC TECH +1
Heterogeneous vehicle queue stability control method and system considering communication time lag
PendingCN113485124ASmall amount of calculationSmooth rideAdaptive controlDynamic modelsControl system
The invention discloses a heterogeneous vehicle queue stability control method and system considering communication time lag, and the method comprises the steps: building a vehicle longitudinal dynamic model, a fixed spacing strategy and a communication topology of a heterogeneous vehicle queue control system, and carrying out the equivalent decomposition of a closed-loop system characteristic equation of a vehicle queue into a plurality of subsystem characteristic equations, converting the stability control problem of the whole vehicle queue control system into the stability control problem of a plurality of subsystems, and greatly reducing the calculated amount of vehicle queue stability control and analysis. By establishing an auxiliary characteristic equation of a subsystem, an infinite system characteristic root solving problem is converted into a limited pure virtual root solving problem, direct rooting of the system characteristic equation is avoided, the accurate time-lag boundary of the vehicle queue can be calculated, it can be guaranteed that the vehicle queue stably runs in the given time-lag boundary, and the obtained stability condition is a sufficient and necessary condition.
Owner:CHANGAN UNIV
Method for calculating short-circuit current of power distribution network containing inverter type distributed power supply
PendingCN114511418AHas the property of second-order convergenceReduce memory requirementsData processing applicationsEmergency protection detectionInverterCharacteristic equation
The invention discloses a method for calculating short-circuit current of a power distribution network containing an inverter distributed power supply. The method comprises the following steps of: 1, establishing an output characteristic equation of the distributed power supply, a node admittance matrix of the network and a fault point boundary condition; step 2, on the basis of the step 1, cyclic calculation is carried out by using a linear iteration method; step 3, on the basis of the steps 1 and 2, performing second-order convergence iterative calculation based on a Newton-Raphson principle and a positive sequence augmented network node voltage equation, and calculating to obtain each node voltage and branch current of the positive sequence network; and 4, calculating node voltage and branch current of the negative-sequence and zero-sequence network by combining the fault point boundary condition in the step 1 based on the calculation result in the step 3, synthesizing fault node phase voltage and branch fault current of the power distribution network by using a symmetric component method, and outputting a result. A reference basis is provided for power distribution network fault positioning, fault diagnosis and the like through an accurate short circuit calculation result.
Owner:JIANGSU ELECTRIC POWER CO +2
Predictive control method and system for stabilizing power fluctuation of hybrid energy storage circuit
ActiveCN110912115AImprove dynamic response characteristicsAvoid uncertaintyBatteries circuit arrangementsLoad balancing in dc networkElectrical engineering technologyMicrogrid
The invention discloses a predictive control method and system for stabilizing power fluctuation of a hybrid energy storage circuit. The invention belongs to the technical field of electrical engineering, the method comprises the steps of predicting equations according to super-capacitor and direct-current bus terminal voltages; obtaining a reference value of the inductive current at the next moment as a tracking target of inner-layer control; a dynamic characteristic equation of inductive current is considered; obtaining a prediction equation of the inductive current; the duty ratio of the two-stage converter is continuously adjusted respectively; and iteratively calculating a two-stage inductive current prediction value, finding out a value closest to the reference value of the inductivecurrent transmitted by the outer layer control at the next moment, and obtaining a PWM signal for controlling the two-stage converter. The DC microgrid controlled by the prediction control method provided by the invention has good dynamic response performance.
Owner:HUAZHONG UNIV OF SCI & TECH
Method for measuring influence of voltage measurement time constant on dynamic stability of unit
ActiveCN112968447AImprove robustnessStrong engineering practicabilityPower oscillations reduction/preventionDynamo-electric machine testingDamping torqueEngineering
The invention discloses a method for measuring the influence of a voltage measurement time constant on the dynamic stability of a unit, and belongs to the technical field of power systems. The method provided by the invention comprises the following steps: introducing additional difference adjustment into a Phillips-Heffron model of a single-machine infinite bus system, and determining a coefficient of the Phillips-Heffron model into which the additional difference adjustment is introduced; obtaining an excitation additional synchronous torque coefficient, a generator overall synchronous torque coefficient formula, an excitation additional damping torque coefficient and a generator overall damping torque coefficient formula; according to the expanded Phillips-Heffron model, obtaining the system oscillation frequency; and quantizing the influence of the voltage measurement time constant on the dynamic stability of the self-shunt excitation unit according to the synchronous torque coefficient and the damping torque coefficient increment. The deduced synchronous torque formula is simple and effective on the basis of the extended Phillips-Heffron model and the characteristic value of the characteristic equation of the model, and the method is suitable for practical engineering application.
Owner:CHINA ELECTRIC POWER RES INST +2
Optimization model for realizing collaborative production of oil and gas wells on offshore platform
PendingCN113153281AQuickly determine the optimal valueEffective guidanceDesign optimisation/simulationBorehole/well accessoriesEngineeringOffshore oil and gas
The invention discloses an optimization model for realizing collaborative production of oil and gas wells of an offshore platform. A method in the model comprises the steps that an electric pump well group production characteristic equation and a gas lift well group production characteristic equation are constructed; the parameter ranges of the platform discharge capacity, the electric pump unit frequency and the total gas injection amount are set; and finally an intelligent optimization system of the offshore oil and gas production platform is established. The single well productivity optimization and the full well group productivity maximization of the offshore platform under the production requirement of limited discharge capacity can be effectively realized. According to the method, blindness and low efficiency of single well parameter adjustment are avoided, and the oil and gas well group production scheme making efficiency under complex conditions can be remarkably improved.
Owner:CHINA UNIV OF GEOSCIENCES (BEIJING)
Flutter critical point prediction method and device
InactiveCN110657939AImprove interferenceImprove accuracyAerodynamic testingComplex mathematical operationsClassical mechanicsEngineering
The embodiment of the invention provides a flutter critical point prediction method and device. The flutter critical point prediction method comprises the following steps: acquiring output response signals, and carrying out ensemble mean calculation on the output response signals, so that a random attenuation label of the output response signals is obtained; according to the random attenuation label, obtaining a target characteristic equation coefficient of the output response signals through fitting calculation; and according to the target characteristic equation coefficient, carrying out calculation to acquire flutter critical points of the output response signals. The flutter critical point prediction method and device provided by the embodiment of the invention has the advantage that aflutter boundary in a wind tunnel experiment can be accurately predicted.
Owner:INST OF HIGH SPEED AERODYNAMICS OF CHINA AERODYNAMICS RES & DEV CENT
Method for judging system stability in milling
InactiveCN104239723ASimple calculationSpecial data processing applicationsSystem stabilityAxial force
The invention discloses a method for judging system stability in milling operation. The stability of a system under a certain group of milling technological parameters is judged by calculating argument variation of a characteristic equation. The method comprises the following steps of (1) acquiring a group of experimental data of component force of tangential, radial and axial force of cutting force; (2) establishing an average cutting force model and a cutting force coefficient model according to an experimental data average measured in an experiment in the step (1), and calculating average cutting force and a cutting force coefficient, wherein C, calculating the average cutting force in a workpiece coordinate system, and D, calibrating the cutting force coefficient; (3) establishing a differential equation for describing a flutter problem of a power system in milling according to the cutting force coefficient obtained in the step (2), converting the equation into a neutral type matrix equation form, and obtaining the characteristic equation by utilizing Laplace transformation; (4) judging the system stability in milling by calculating the argument variation of the characteristic equation according to any group of technological parameters consisting of axial depth of cut, radial depth of cut, a spindle speed and a feed rate. The method has the beneficial effects that the method is simple in calculation, and a new stability judging method is provided for theoretical study of milling.
Owner:HEILONGJIANG UNIVERSITY OF SCIENCE AND TECHNOLOGY
Method for judging small-interference stability of converter grid-connected system under polar coordinates
InactiveCN111146807ACalculation of Stability MarginJudgment stabilitySingle network parallel feeding arrangementsPower oscillations reduction/preventionDynamic equationControl engineering
The invention discloses a method for judging the small-interference stability of a converter grid-connected system under polar coordinates. The method comprises the steps: acquiring an admittance model of a converter and a power grid under coordinates by linearly processing a dynamic equation of the converter grid-connected system, and then establishing an admittance model of the converter and anadmittance model of the power grid; performing coordinate transformation on the admittance model of the converter and the admittance model of the power grid under the dq coordinates to obtain a converter admittance model and a power grid admittance model under the polar coordinates; obtaining a single-input single-output closed-loop system model and a closed-loop characteristic equation, and performing judging by using a Nyquist curve according to the closed-loop characteristic equation or calculating the stability margin of the system according to the closed-loop characteristic equation to obtain a result whether the current control parameter of the converter can enable the converter to operate stably or not. According to the method, the stability margin of the converter grid-connected system can be effectively calculated, the influence of the control parameters of the converter on the stability of the grid-connected system is judged, and the instability problem caused by improper setting of the control parameters of the converter is avoided.
Owner:ZHEJIANG UNIV +2
Geometric parametric modeling method and device for aircraft fuselage frame structure
ActiveCN112528406AAvoid randomnessAvoid errorsGeometric CADSustainable transportationClassical mechanicsGeometric modeling
The invention belongs to the technical field of geometric modeling, and particularly relates to a geometric parametric modeling method and device for an aircraft fuselage frame structure. The method comprises the steps: intercepting a curve on the inner profile geometry and the outer profile geometry of a fuselage frame according to a frame position plane, and obtaining a first inner profile geometry curve and a first outer profile geometry curve; constructing a first characteristic equation of the inner shape surface and the outer shape surface, intercepting discrete point coordinates on thefirst inner shape surface geometric curve and the first outer shape surface geometric curve, and performing curve reconstruction according to the first characteristic equation to obtain a second innershape surface geometric curve and a second outer shape surface geometric curve; constructing a coefficient control equation, respectively adjusting the second inner surface geometric curve and the second outer surface geometric curve, and obtaining a contour curve of the fuselage frame according to the two adjusted curves; and constructing a second characteristic equation, intercepting nodes on the contour curve of the fuselage frame according to the second characteristic equation, and taking the nodes as positions for arranging frame reinforcing ribs.
Owner:SHENYANG AIRCRAFT DESIGN INST AVIATION IND CORP OF CHINA
Nonlinear modeling and identification method of fractional order permanent magnet synchronous motor
ActiveCN110889240AAccurate dynamic behaviorAccurate descriptionDesign optimisation/simulationComplex mathematical operationsAlgorithmPermanent magnet synchronous motor
The invention provides a nonlinear modeling and identification method of a fractional order permanent magnet synchronous motor. The method comprises the following steps of establishing an electromagnetic torque and mechanical characteristic equation of a fractional order motor; converting a three-phase static coordinate system into a two-phase rotating coordinate system through the space vector transformation; establishing an estimation system model according to an actual system model; sampling the states of the actual system and the estimation system, and establishing an objective function; and searching the optimal combination of the independent variable order and the parameter of the objective function by using a genetic algorithm, so that the value of the objective function is minimum.Compared with a traditional modeling mode, the fractional calculus theory is adopted to establish a motor model, so that the model is closer to the actual characteristics of the motor, and the dynamic behavior of the motor can be described more accurately. A traditional motor identification method adopts a strategy that id =0, so that the motor is simplified into a linear system. The identification method of the present invention does not carry out linearization processing on the motor system, so that the precision of the established model is higher.
Owner:DALIAN MARITIME UNIVERSITY
Prediction method of shale adsorption capacity based on adsorption characteristic curve and characteristic equation
InactiveCN108446526BTemperature dependentDesign optimisation/simulationComplex mathematical operationsPredictive methodsPhysical chemistry
Owner:CHINA UNIV OF GEOSCIENCES (WUHAN)
Intelligent operation optimization method and system for gas-fired boiler unit and storage medium
The invention discloses an intelligent operation optimization method and system for a gas-fired boiler unit. The method comprises the following steps: S1, collecting original data of a gas-fired boiler unit in real time; S2, storing and managing the collected original data by utilizing database management software; S3, establishing a gas-fired boiler unit operation characteristic equation according to the original data; S4, establishing a gas-fired boiler unit optimization model according to the parameters of the gas-fired boiler operation characteristic equation; S5, obtaining an optimal solution of the gas-fired boiler unit optimization model through a coordinate rotation method; and S6, performing optimization adjustment according to the optimal solution result. According to the intelligent operation optimization method and system for a gas-fired boiler unit disclosed by the invention, through a big data mining technology, a coordinate rotation method and other intelligent optimization algorithms, valuable information is rapidly obtained from boiler unit production data, and the optimal operation value in actual production is found out to guide operation personnel in operation.Thus, theoretical support is provided for improving economic benefits of thermoelectric enterprises.
Owner:汉谷云智(武汉)科技有限公司
Control parameter optimization method of automobile automatic steering system containing feedback time lag
PendingCN114253128AImprove stabilityImprove securityControllers with particular characteristicsAutomatic steeringTime lag
The invention discloses a control parameter optimization method for an automobile automatic steering system containing feedback time lag. The method comprises the steps that (1) an automobile automatic steering system dynamic model of a PD controller containing the feedback time lag is established; 2) obtaining a system characteristic equation through Laplace transformation, and substituting the system characteristic equation into the lowest stability margin translation equation to a critical node so as to obtain a real and imaginary part equation; 3) deducing a system instability boundary curve and an oscillation instability boundary curve under the condition that the main frequency of the system is zero and not zero; 4) substituting the target attenuation rate of the controller, drawing two boundary curves on a control parameter plane, and obtaining a closed parameter domain meeting target requirements; and 5) when the two boundaries coincide critically, obtaining the optimal system attenuation rate which can be realized by the system under time lag, and calculating the optimal control parameter combination. According to the method, the control meeting the expected performance under the time lag can be efficiently realized at low cost, so that the time lag effect can be obviously inhibited, and the driving safety of the automatic steering system of the automobile is effectively improved.
Owner:HEFEI UNIV OF TECH
Anisotropic reservoir fracture pressure prediction method and device
PendingCN114841019AThe calculation result is accurateComprehensive considerationDesign optimisation/simulationComplex mathematical operationsEngineeringCharacteristic equation
The invention discloses an anisotropic reservoir fracture pressure prediction method and device. The method comprises the steps that basic parameters needed by calculation are collected; solving by adopting a high-order mixed partial differential characteristic equation method and a stress decomposition and superposition method, establishing a horizontal shaft stress model, and calculating a stress component at any position; a three-dimensional displacement discontinuous method is adopted to solve extra induced stress generated by strain dislocation of surrounding rocks caused by the perforation holes, then the total stress distribution parameters of the horizontal shaft are superposed, and the induced stress of the perforation holes is obtained through the stress decomposition and superposition principle; calculating stress distribution around the perforation holes according to reservoir parameters corresponding to the perforation holes; and calculating the anisotropic tensile strength by using the tensile strength of the vertical bedding and the tensile strength of the parallel bedding, and further calculating the fracture pressure of the anisotropic reservoir based on an anisotropic failure criterion. Compared with the prior art, the anisotropic reservoir fracture pressure prediction model provided by the invention is more perfect in consideration factors and more accurate in calculation result.
Owner:SOUTHWEST PETROLEUM UNIV
Fuel cell wide-area injector design method and device
ActiveCN109033579BAddressing narrow workload challengesExtended usable load rangeDesign optimisation/simulationSpecial data processing applicationsFuel cellsMathematical model
The invention discloses a method and apparatus for designing a fuel cell wide area ejector. The method comprises the following steps: obtaining fuel cell stack parameters and working conditions; establishing a steady-state characteristic equation of fuel cell ejector and the characteristic equation of ejecting fluid with water. The steady-state characteristic equation of fuel cell ejector and thecharacteristic equation of ejecting fluid with water are coupled into the mathematical model of fuel cell ejector. The available load range of the ejector is predicted by using the model, and the hydrogen ejection performance curve in the available load range of the ejector is obtained. The initial parameters are determined in order to optimize the nozzle diameter, mixing chamber diameter / nozzle diameter, mixing chamber length / mixing chamber diameter, nozzle location size of the parameter values. This method takes into account both the performance improvement and the widening of the availableload range in the ejector parameter optimization design phase, and provides an effective way to design hydrogen ejector with a wide range of available load range, which provides an effective way to solve the problem that the fuel cell ejector has a narrow working load range.
Owner:TSINGHUA UNIV
Optimal robust fractional order pi for time-delay systems λ Optimization method of d controller
ActiveCN111443600BSatisfy the frequency domain specificationImprove robustnessControllers with particular characteristicsAutomatic controlFractional-order control
The invention belongs to the technical field of automatic control, and discloses an optimal robust fractional order PI for a time-delay system λ Optimization methods for D controllers. The method comprises the following steps: (a) constructing the closed-loop transfer function of the control system to be optimized; (b) obtaining the closed-loop transfer function with respect to the PI λ The characteristic equation of the unknown parameter in the D controller; (c) construct the constraint condition that the first-order inertia delay control system to be optimized needs to satisfy, utilize described characteristic equation to determine described PI λ The value range of the unknown parameter in the D controller is solved according to the constraints and the value range and the PI is obtained λ The values of the unknown parameters in the D controller are used to determine the PI λ D controller, which realizes the optimization process. Through the present invention, the realization of PI λ The optimization of the D controller makes the control system have strong robustness and optimal dynamic performance.
Owner:HUAZHONG UNIV OF SCI & TECH
A Vibration Analysis Method for Uniform Section Beam Structure
ActiveCN107808048BIncrease the number of loop iterationsFast convergenceGeometric CADComplex mathematical operationsAxial displacementStrain energy
The invention provides a vibration analysis method for a uniform section beam structure. The method comprises the steps that geometric size characteristics of the beam structure are extracted, a displacement field of the beam structure is separated to be in-section displacement and axial displacement; fitting is performed on the in-section displacement of the beam structure; extension is performedon the axial displacement of the beam structure; the in-section displacement and the axial displacement of the beam structure are combined to calculate integral displacement of the beam structure; strain vectors and stress vectors of an elastic plate structure are calculated; strain energy, a kinetic energy equation and boundary energy of the beam structure are calculated; a structural Lagrange energy function is established to obtain a core mass matrix and a stiffness matrix of the beam structure; an integral mass matrix, an integral stiffness matrix and an overall mass matrix are solved through iterative looping of the core matrix, and then a characteristic equation of the structure is obtained; and a characteristic equation matrix of the beam structure is solved, and inherent frequencyand a vibration mode are obtained through calculation. The method is suitable for the beam structure with multiple boundary conditions and multiple section shapes and is high in precision, fast in convergence, low in calculation cost and simple in calculation method.
Owner:HARBIN ENG UNIV
A microgrid control cycle stability analysis method and system
ActiveCN112260251BGuaranteed stabilityEnergy industryDc source parallel operationMicrogridLoop control
The present disclosure belongs to the field of microgrid operation control, and discloses a method and system for analyzing the stability of a microgrid control period, establishing a small signal model of a microgrid distributed closed-loop control system in which each distributed power source corresponds to different control periods, and based on Euler discretization Obtain discrete characteristic equations, track the critical characteristic root locus of the system characteristic equations according to the least common multiple of multiple control periods, search for possible characteristic roots on the unit circle, and then calculate the control period to stabilize the microgrid, and control the control between different distributed power sources. The relationship between cycles is studied to provide a basis for the selection of distributed control cycles, to achieve average voltage recovery and active power equalization, and to improve the stability and dynamic performance of microgrids.
Owner:INST OF ECONOMIC & TECH STATE GRID HEBEI ELECTRIC POWER +2
A Vibration Control Method of Rigid-Flexible Electromechanical Servo System
ActiveCN110187723BSuppress residual vibrationMechanical oscillations controlControllers with particular characteristicsFractional-order controlVibration control
The invention discloses a vibration control method of a rigid-flexible coupling electromechanical servo system, comprising: separately collecting encoder data on a drive motor and a load motor, obtaining the torsion angles at both ends of a flexible shaft in real time, and calculating the flexible shaft The torsion angle of the micro-element at any position on the above is calculated according to the length, polar moment of inertia, elastic modulus and moment of inertia of the flexible shaft to obtain the frequency domain characteristic equation; using the frequency domain characteristic equation to calculate the described The coupling torque between the flexible shaft and the rigid drive flywheel; the balance equation of the rigid drive flywheel is established; the coupling torque is brought into the balance equation to obtain the fractional transfer function model of the system; according to the fractional transfer function model, establish a fractional order controller, and use the controller to control the vibration of the system. The method involved in this patent accurately describes the dynamic behavior of the viscoelastic material through the fractional order model, and effectively suppresses the residual vibration of the system.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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