122 results about "Analytic expression" patented technology

The invention belongs to the technical field of aircraft structure design, and particularly relates to an aircraft arbitrary space four-bar mechanism parameter optimization method, which comprises the following steps: firstly, determining input conditions or preposed requirements of a four-bar mechanism, secondly, establishing a mathematical model of a four-bar mechanism optimization problem, and then, carrying out derivation and analysis to obtain a four-bar mechanism parameter optimization result. The method comprises the following steps: establishing an analytic expression of parameter variables of the four-bar mechanism and compiling a corresponding calculation program, then carrying out iterative optimization on the parameters of the four-bar mechanism by utilizing an optimization algorithm, and finally outputting an optimization result to obtain an optimal design parameter.

The invention discloses a geometric analytic expression three-dimensional reconstruction method, and relates to the technical field of computer vision and three-dimensional environment perception. According to the method, for an application scene with a target area located in a known space attitude plane, an accurate geometric mapping relation among a navigation coordinate system, a camera coordinate system and an imaging plane is constructed by fusing a visible light image, a single-point distance measurement value and attitude information output by an attitude sensor (such as an IMU); and pixel-level depth estimation is realized by adopting an analytic expression calculation strategy, so that high-precision and low-complexity three-dimensional reconstruction of a coplanar region is completed.

The application discloses a kind of analytic expression probabilistic power flow calculation method, device and storage medium.The application is determined after the mapping relationship between the injection power of node and the operating state of power system by linear power flow model, using first-order polynomial fitting correction method to revise the operating state of power system, make the operating state of the power system after revision be closer to real operating state, according to the mapping relationship between the injection power of node and the operating state of power system after revision, update linear power flow model, carry out analytic expression probabilistic power flow calculation using updated linear power flow model, to effectively improve the accuracy of probabilistic power flow calculation.

The invention discloses a linear variation stiffness matrix method for suspension bridge space cable forming form finding, relates to the technical field of bridge numerical simulation, and solves the defects of a stiffness matrix in the process of solving the suspension bridge forming form finding through a segmented catenary method. The method comprises the steps that a suspension bridge is simplified into a space cable system composed of a main span, a side span and an anchor span, and the main span, the side span and the anchor span are sequentially subjected to a bridge forming and shape finding process; the linear change stiffness matrix solved in the bridge forming and shape finding process of the main span is used for representing the linear relation between the displacement change of the control point and the initial force change of the main cable; according to the method, an analytical expression of a linear change stiffness matrix is deduced, and an efficient iterative algorithm is established. According to the algorithm, the initial force correction is directly calculated according to the displacement error of the control point in each iteration.

A double-lane millimeter wave vehicle networking safety transmission method, system, device and medium based on STAR-RIS, the method comprising: constructing a STAR-RIS assisted double-lane millimeter wave vehicle networking communication scene; based on the propagation characteristics of millimeter wave signals, combining the channel fading characteristics under the conditions of line-of-sight and non-line-of-sight transmission and the transmission and reflection functions of STAR-RIS, calculating the channel gain of the cascaded channel of the STAR-RIS assisted link; based on the random geometry theory, respectively calculating the probability density functions of the associated distances of the direct link, the STAR-RIS reflection link and the STAR-RIS transmission link; constructing a dynamic link association strategy supporting ternary selection; establishing a signal-to-interference-and-noise ratio model under three association modes; combining the physical layer security performance index definition, calculating the closed-form analytical expressions of the connection interruption probability and the secrecy interruption probability, and verifying the security gain of STAR-RIS; the present application has the advantages of effectively overcoming the half-space coverage blind area of the traditional reflective RIS, and improving the link connection reliability and physical layer safety transmission performance under the double-lane complex shielding environment.

The invention relates to a rapid calculation method and system for a space magnetic field of a circular coil. The method comprises the following steps: converting an integral expression of a Biot-Savart law into a closed analytical solution containing first and second types of complete elliptic integrals; on the basis of an analytical expression of elliptic integration, the magnetic field intensity and direction generated by the coil at any point in the space can be efficiently and precisely calculated, and the defects that traditional finite element simulation calculation is complex, consumed time is too long, and efficiency and precision of a direct numerical integration method are difficult to consider at the same time are overcome. The method is particularly suitable for application scenes such as WPT system design, multi-transmitting-coil amplitude-phase control optimization and real-time simulation which need to carry out rapid and frequent calculation on the magnetic field. According to the method, full-automatic rapid calculation from physical parameter input to magnetic field result output is achieved, the core advantage of the method is that an analytical formula is utilized, the tedious process of numerical simulation and integration is avoided, and the calculation efficiency is remarkably improved while high precision is guaranteed.

The application relates to the technical field of estimation of maximum frequency deviation of power grid nodes and is used for solving the problem that the existing estimation method of maximum frequency deviation of power grid nodes cannot reflect the time-space difference characteristics of frequency response of an interconnected power system. First, a two-region frequency response model TAFR considering the time-space difference characteristics of frequency of power grid nodes is established, a time-domain analytical expression describing the node frequency difference mechanism is obtained by adopting the mode analysis and average system frequency model aggregation idea, and a maximum frequency deviation estimation method reflecting the time-space difference is proposed on the basis of the analytical expression. The established TAFR model considers the distribution of tie-line parameters, system inertia and damping, and equivalently processes the new energy frequency modulation parameters, compared with the existing frequency dynamic response model, the model has improved accuracy and applicability while ensuring the time-space difference.

The invention discloses a turbulence model construction method for aerodynamic simulation of a hybrid three-compartment vehicle, and relates to the field of model simulation, and the method comprises the steps: S1, employing a flow field inversion method, and obtaining the dense space distribution of a turbulence model correction term; s2, screening local flow field characteristics related to the correction distribution characteristics; s3, training by adopting a symbol regression method to obtain an analytical expression of a turbulence model correction term; s4, through mathematical derivation, an analytical expression of a correction term is migrated into the standard model, so that the correction term is added in front of a damage term of a transport equation of the dissipation rate of the standard model; s5, selecting an initial value of a to-be-calibrated coefficient in the correction item according to the smoothness degree of the chassis of the hybrid three-compartment vehicle; and S6, calibrating the to-be-calibrated coefficient in the expression in the step S4 on the basis of real vehicle experimental data of the hybrid three-compartment vehicle to obtain the turbulence model for aerodynamic simulation of the hybrid three-compartment vehicle.

The invention belongs to the technical field of ship intelligent digital optimization design, and particularly relates to a ship global deformation and optimization method, program and equipment considering drainage volume precision control and deformation rationality and a storage medium. The analytical expression of the drainage volume variation about the global deformation parameter is obtained based on the numerical integration and the recursion formula, the reasonable deformation parameter range of the ship body is determined based on the global deformation modification function and the regular design space, the ship body does not need to be actually deformed, the corresponding volume variation can be directly predicted according to the design parameter, and the calculation accuracy is improved. Accurate feedforward control of volume constraint and direct judgment of rationality of the deformed ship are realized. On the basis, rapid optimization of any ship type structure under the constraint of reasonable deformation and accurate volume control is realized in combination with an agent model. According to the method, a traditional'design-verification-adjustment 'experience iteration process is converted into deterministic one-step calculation, and subsequent optimization can be directly carried out in a pre-verified reasonable design space.

The invention discloses a two-point grounding fault model analysis method in a neutral point non-effective grounding mode, and aims to solve the problem that a unified accurate mathematical model suitable for a neutral point non-grounding and arc suppression coil grounding system under an in-phase two-point grounding fault is lacked in the prior art. According to the method, a fault network topology is reconstructed, a multivariate function equation set containing a fault position, ground capacitance, arc suppression coil parameters and a power supply initial phase angle is established, explicit analytical expressions of zero-sequence voltage current and phase voltage current are deduced, and a transient process is modeled in combination with a state space method. And accurate description of a fault characteristic quantity spatio-temporal evolution rule is realized. By adopting the above technical scheme, the method can provide a modeling basis which can be directly called for high-fidelity simulation platforms such as RTDS, and supports intelligent protection algorithm development and fault diagnosis system optimization.

The application relates to the technical field of wind power generation, and discloses a wind turbine design method adopting a frictional tuned mass damper, which adds a frictional tuned mass damper to a man platform in a tower drum of a wind turbine, establishes a motion equation of the wind turbine after adding the frictional tuned mass damper based on a structural dynamics principle, deduces a mathematical analytic expression of a system dynamic coefficient, and obtains parameters of the frictional tuned mass damper through a system optimization theory. The application solves the problems that the prior art is difficult to realize damping through the tuned mass damper in the narrow space in the cabin or the tower drum, and the damping control effect is poor.

The application discloses a control method for primary frequency modulation in a power dead zone range of a hydroelectric generating set, and belongs to the technical field of hydroelectric generating set regulation. The method comprises the following steps: S1, calculating H1 and H2 of a water diversion system according to the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the generating set; S2, calculating a dynamic analytical expression of the generating set power when a frequency unit step disturbance occurs; S3, calculating a first-order differential link coefficient decomposed by a second-order correction link based on the dynamic analytical expression of the generating set power; and S4, calculating the output of a PID speed regulator in a current sampling period. The scheme calculates the oscillation link transfer function parameters in a dynamic process, and a second-order system correction transfer function of a frequency given value is designed on the basis, so that the oscillation phenomenon of the generating set power does not occur when the frequency given value of the generating set changes, the problem that the power exceeds the power dead zone in the dynamic process is prevented, and a limiting link is arranged at the frequency deviation value to ensure that the power steady-state value exceeds the power dead zone range.

The invention discloses an integral transformation fracture phase field model implementation method of a random-order polynomial cohesion law, and belongs to the technical field of phase field model finite element analysis. The method comprises the following steps: inputting a parameter equation of a polynomial cohesion law of any order and a target order into a subprogram; deducing a cohesion eigenfunction of a random-order polynomial cohesion law by using a subprogram to determine an analytical expression of a random-order polynomial energy density eigenfunction, solving a target-order polynomial energy density eigenfunction expression and first two-order derivatives thereof, and determining an expansion expression at a zero point by using Maclaurin series; and inputting the target-order polynomial energy density eigenfunction expression, the first two-order derivatives thereof and the expansion expression at the zero point into a phase field model solver to obtain a calculation result of the target-order polynomial integral transformation fracture phase field model. According to the method, the simulation calculation of the integral transformation fracture phase field model of the target-order polynomial cohesion law can be realized under a universal finite element framework, and the accuracy and the efficiency are improved.

The invention discloses a low-frequency oscillation optimization method of an electric power system containing an SDC and a DFIG based on balanced truncation and series control compensation. The low-frequency oscillation optimization method comprises the following steps: 1, establishing a linear analysis model of a wind power grid-connected electric power system containing a synchronous generator SG, the DFIG and an additional damping controller SDC; 2, truncation processing is carried out on a state matrix in the state matrix equation of the main system after balance transformation, and a main system state matrix equation after order reduction is obtained; 3, constructing a time domain matrix of the system containing the series feedback controller to obtain a system state matrix equation containing the series feedback controller; 4, solving a characteristic value and a damping ratio of the system state matrix equation containing the series feedback controller, and constructing a control parameter analytic expression of the characteristic value and the damping ratio to the SDC in a low-frequency oscillation mode; and 5, solving by using the low-frequency oscillation optimization model of the SDC to obtain the optimal adjustment amount of the control parameters of the SDC. According to the invention, the control compensator is added to optimize the characteristic value under low-frequency oscillation and the control parameters of the SDC, so that the stability of the system is optimized.

The invention discloses a turbulence model construction method and device, electronic equipment, a storage medium and a vehicle, and relates to the field of sound production control, and the method comprises the steps: obtaining the experiment data of a target vehicle type separation flow, and determining the dense space distribution characteristics of a turbulence model correction term according to the experiment data; determining a first flow field feature related to the dense spatial distribution feature in the flow field features of the separation flow; according to the first flow field feature and the dense space distribution feature, determining an analytical expression of a turbulence model correction term; and constructing a turbulence model for calculating the air resistance of the target vehicle model based on the analytical expression. The precision of the turbulence model for calculating the air resistance of the target vehicle model can be improved, so that the research and development efficiency is improved and the research and development cost is reduced.

The application belongs to the technical field of communication system, and particularly relates to a method and system for deriving optimal degree distribution of regular LDPC code based on AWGN channel. The method comprises the following steps: S1, taking the maximization of code rate of the regular LDPC code as a criterion and taking the decoding success as a prerequisite, a target function with a constraint condition is constructed; S2, fixing the degree d v of the variable node, based on the fixed point analysis theory, a theoretical analytic expression of the degree d c of the check node in the LDPC code is derived, and an inverse function of the target function in the non-convex optimization problem is solved; S3, based on the mathematical set theory, the uncertainty in the inverse function solving problem in the step S2 is solved, and the optimal degree distribution of the LDPC code under the AWGN channel is obtained. The application has the characteristics of improving the channel coding performance in the communication system.

The invention provides a new energy networking flexible direct current system fault current sequence component characteristic characterization method, which comprises the following steps of: considering a fault ride-through control strategy of alternating current transmission line side equipment in a new energy networking flexible direct current system, and establishing an equivalent sequence network diagram of the system; solving analytic expressions of fault current sequence components on two sides of the line under different fault types based on the equivalent sequence network diagram; quantizing a fault current sequence component corresponding to each fault type through an analytical expression; and extracting influence parameters of the fault current sequence component, and representing the characteristics of the fault current sequence component in combination with the analytical expression. According to the method, the fault current sequence components under different fault types are systematically quantified, the association rule of the influence parameters and the fault current sequence components is represented, a theoretical basis is provided for formulation, optimization and parameter adjustment of a conventional control strategy, the adaptability and the operation reliability of the control strategy to different fault scenes are remarkably improved, and the method is suitable for large-scale popularization and application. And technical support can be directly provided for safe and stable operation of the new energy network construction flexible direct current system.

The invention discloses a milling chatter stability domain prediction method and system based on an approximate analysis method, and the method comprises the steps: employing a Fourier approximation method to represent a milling steady-state response based on a milling direction coefficient and a time delay characteristic in a milling dynamic model; applying small disturbance to the steady-state response, substituting the steady-state response into the milling dynamic model, and obtaining a milling stability analysis expression by applying a Galerkin process; substituting the bifurcation condition into the stability analysis expression based on the characteristics of the stability domain boundary corresponding to the milling stability bifurcation condition, and deducing an approximate implicit analytical expression of the milling stability boundary; solving the implicit analytical expression by adopting a numerical continuation method to obtain a stability boundary expressed by rotating speed-cutting depth; according to the method, the stability lobe graph is obtained, the problems of initial continuation point selection and transition between lobes with different stability in the solving process are solved, complete and accurate construction of the stability lobe graph is achieved, theoretical guidance of flutter-free working conditions is provided for milling, and the method has important engineering application value.

This invention discloses a performance optimization method for a tristable energy harvester under low-frequency excitation based on vibration resonance, belonging to the field of energy harvester optimization. The implementation method is as follows: a standard rectifier circuit is selected as the nonlinear collection circuit and connected to the energy harvester to achieve a stable DC output; a strongly nonlinear system model of the electromechanical coupled tristable energy harvester system is established; the slow variable equation of the tristable energy harvester system is derived using the variable separation method; the steady-state solution and analytical expression of the DC power of the tristable energy harvester system are derived using the harmonic balance method; an optimization model of the tristable energy harvester system under low-frequency excitation is obtained based on vibration resonance; the influence of low-frequency excitation amplitude, low-frequency excitation frequency, stiffness coefficient, time constant ratio, and electromechanical coupling coefficient on the collection performance of the tristable energy harvester system is analyzed using the optimization model, and the optimal combination is selected to achieve efficient energy harvesting of the tristable energy harvester system under low-frequency excitation.

The application discloses an insect radar body size parameter inversion method based on minimum polarization RCS. Firstly, the relationship between a polarization pattern shape and a scattering matrix eigenvalue is derived based on a symmetrical insect model, and on the basis, an analytic expression of minimum polarization RCS is derived, and finally, the relationship between the minimum polarization RCS and insect body length and weight is analyzed, and an empirical formula for inversing the insect body length and weight based on the minimum polarization RCS is given. The application provides an insect radar target body size parameter inversion method with good polarization error resistance and high precision, which is helpful to realize accurate species identification of migratory pests and improve the management ability of the migratory pests.

The application discloses a two-point grounding fault model analysis method under a neutral point non-effective grounding mode, and aims to solve the problem that the prior art lacks a unified accurate mathematical model applicable to a neutral point non-grounding and arc suppression coil grounding system under a same-phase two-point grounding fault. The method reconstructs a fault network topology, establishes a multi-element function equation group containing a fault position, a ground capacitance, an arc suppression coil parameter and a power supply initial phase angle, deduces an explicit analytic expression of zero sequence voltage and current and phase voltage and current, and realizes accurate characterization of a time-space evolution law of fault characteristic quantities by combining with state space method modeling transient process. By adopting the above technical scheme, the application can provide modeling basis which can be directly called for a high-fidelity simulation platform such as RTDS, and support intelligent protection algorithm development and fault diagnosis system optimization.

This invention provides an adaptive admittance method and system based on the optimal control LQR theory, including constructing an environmental dynamics model and a robotic arm admittance control model, and deriving their interactive dynamics model; defining state variables and control inputs, and establishing a standard form state-space equation; constructing a quadratic performance index function, transforming admittance parameter optimization into an LQR problem; substituting the linear quadratic regulator framework into the quadratic performance index function, transforming the LQR problem into solving the Riccati matrix differential equation, and deriving analytical expressions for virtual optimal stiffness and virtual optimal damping; within the robotic arm control sampling frequency, inputting real-time collected environmental contact forces and the actual pose of the robotic arm end effector, along with set weighting coefficients, into the analytical expressions to calculate optimal virtual stiffness and damping; and then calculating pose corrections based on the admittance control model to correct the robotic arm's motion trajectory.

The application discloses a power system stability domain solving method based on adaptive prediction correction and related equipment, and relates to the field of power system stability analysis. The method comprises the following steps: obtaining device parameters and operation parameters of a power system, constructing a stability judgment function and establishing a parameter space model; tracking the stability domain boundary in the parameter space by using a prediction-correction strategy, and obtaining a boundary point set through zero-crossing point searching; constructing a local neighborhood based on the boundary points and extracting a normal vector, which is used for representing the local geometric features of the boundary; clustering the boundary points based on the normal vector, so as to realize segmentation of the boundary corresponding to different critical modes; further constructing a multivariate orthogonal polynomial model for each boundary subset and performing fitting, so as to obtain an analytical expression of the stability domain boundary, thereby forming a structured stability domain model. The application can efficiently and accurately track the stability domain boundary in a multi-parameter space, and realize identification and analytical modeling of multiple critical modes.

The invention discloses a new energy frequency modulation gain setting method, device and equipment, and the method comprises the steps: collecting power system equipment parameters and new energy meteorological data, calculating the wind-solar power generation output and permeability, building an aggregation model considering the new energy permeability and frequency modulation gain, and carrying out the adjustment of the frequency modulation gain. And after a frequency variation analytic expression is extracted, a frequency modulation gain instruction is optimized and generated in two stages to complete setting. The system working condition change is dynamically matched, and the frequency modulation gain setting scheme is synchronously adjusted along with the working condition. In the first stage, the fluctuation amplitude is controlled by taking suppression of a frequency change extreme value as a target, and in the second stage, the regulation quantity is optimized in combination with stability constraint, so that large frequency fluctuation caused by unreasonable gain setting is avoided through double guarantee, and the frequency stability of the power system is enhanced; a complex setting problem is disassembled into a sum setting stage and a fine setting stage, the solving difficulty is reduced, the efficiency is improved, meanwhile, due to the fact that key influence factors are included in the aggregation model, the frequency characteristics of the system can be accurately described, and reliable support is provided for setting.

The application provides a system and method for generating an index topology graph based on an analytical expression, and relates to the technical field of computer processing, comprising an index topology configuration module, a task scheduling module, an index calculation module and a data display module; the index topology configuration module is used for performing entity recognition analysis on a plurality of user input expression texts respectively to obtain corresponding index topology structures, and sending the index topology structures to the task scheduling module; the task scheduling module is used for creating tasks according to a preset scheduling rule to obtain corresponding index calculation tasks; the index calculation module is used for calculating task priorities according to all the index calculation tasks to obtain index priority calculation data; and the data display module is used for receiving the index priority calculation data and obtaining a target topology graph through the index priority calculation data. The application realizes improved topology graph generation efficiency.

The invention discloses a construction method of a subway track irregularity spectrum, and aims to solve the technical problem that an existing classical track spectrum model is difficult to accurately and universally describe actual irregularity characteristics of subway lines in China. Comprising the following steps: a) acquiring actually measured track irregularity data of at least one subway line; b) based on the actually measured track irregularity data, calculating to obtain a power spectral density spectral line, the power spectral density spectral line representing a change relation of a power spectral density value along with a spatial frequency; c) preprocessing the power spectral density spectral line, wherein the preprocessing comprises identifying and eliminating periodic spectral peaks caused by track geometrical characteristics; d) the preprocessed power spectral density spectral line is converted to a logarithm-logarithm coordinate system, the abscissa is the logarithm value of the spatial frequency, and the ordinate is the logarithm value of the power spectral density value; and e) under the logarithm-logarithm coordinate system, establishing an analytical expression of the track irregularity power spectrum density through quintic polynomial fitting.

The application discloses a kind of pure angle target trajectory estimation methods, this method will typical target motion model be converted into the autoregressive moving average model of position component to realize state decoupling, by adjusting the relationship between pseudo-linear least square cost function and process noise energy to obtain regularized pseudo-linear least square model.To reduce the estimation deviation generated by the correlation between pseudo-linear measurement matrix and noise, the regularized instrumental variable least square position estimation is obtained by using instrumental variable estimation method.The method of the application obtains the analytical expression of batch estimation of azimuth position component in the framework of regularized least square estimation.The method has linear time calculation complexity, and its estimation performance is irrelevant to initial state.

This invention discloses a rapid voltage calculation method for a radial virtual power plant based on the branch U-S theorem, belonging to the field of power system analysis and calculation technology. The method includes: acquiring the power network topology of the radial virtual power plant; numbering each node in the network layer by layer; collecting the voltage and power of each node and the impedance data of each branch; calculating the voltage of each node layer by layer based on the branch U-S theorem, according to the known head-end voltage and the power flowing into the tail end; and outputting the voltage calculation results for each node. The branch U-S theorem provides an analytical expression for the tail voltage of a single power branch. This invention avoids the complex iterative process required by traditional voltage calculation methods, enabling rapid and accurate calculation of the voltage of each node in a radial virtual power plant, significantly improving computational efficiency, and is suitable for scenarios such as real-time monitoring, rapid dispatching, and market response of virtual power plants.

This invention belongs to the field of rotating machinery condition monitoring and fault diagnosis technology. It proposes a bearing failure assessment method and system. The method involves acquiring bearing vibration signals and performing mean and absolute value removal processing to obtain the signal to be processed. Next, a lower threshold for the tail is determined, and a set of tail samples with amplitudes greater than this threshold is selected. Then, a soft-truncated power-law distribution model is constructed based on the tail sample set, and the distribution parameters, including the power-law tail exponent, truncation scale parameter, and truncation smoothing exponent, are solved using maximum likelihood estimation. Furthermore, an analytical expression for the improved Gini index is constructed based on the distribution parameters, and the bearing degradation degree index is calculated. Finally, a bearing degradation curve is constructed based on the degradation degree index for different time periods. This invention accurately characterizes the tail impact features of vibration signals using a soft-truncated power-law model and quantifies the degradation degree using an improved Gini index, effectively assessing the health status and failure trend of rolling bearings.