122 results about "Perturbation method" patented technology

Recommendation systems are widely used in Internet applications. In current recommendation systems, users only play a passive role and have limited control over the recommendation generation process. As a result, there is often considerable mismatch between the recommendations made by these systems and the actual user interests, which are fine-grained and constantly evolving. With a user-powered distributed recommendation architecture, individual users can flexibly define fine-grained communities of interest in a declarative fashion and obtain recommendations accurately tailored to their interests by aggregating opinions of users in such communities. By combining a progressive sampling technique with data perturbation methods, the recommendation system is both scalable and privacy-preserving.

The invention relates to a transient stability distributed simulation method of an electric power system, belonging to the transient stability analysis technical field of the electric power system; the transient stability distributed simulation method is characterized in that: variable dimension of boundary coordination equation is reduced to one half of that of a partitioning method based on connecting line by using the partitioning method based on a node decomposing method, so as to improve the simulation efficiency; the accurate initial Jacobi inverse matrix is obtained by using a boundary perturbation method, so as to reduce iterations; the calculation process is accelerated by comprehensively adopting the methods that the boundary node voltage value of the next time step is pre-estimated and the Jacobi inverse matrix is coordinated and dynamically updated simultaneously in multiple time steps; by adopting coordination algorithm based on inverse Broyden quasi-Newton method, the solving times of the boundary coordination equation are reduced greatly, so as to improve the simulation efficiency. In the technical proposal, the data interface is simple, the data transmission capacity is low, the system model is simplified, superlinear convergence speed close to the newton method is provided, and hyper real-time simulation can be realized in a wide area communication network, therefore, the method is conveniently applied to the practical electric power system.

The invention relates to a micro-water content test system based on a resonant cavity perturbation method, which covers the technical fields of resonant cavities, frequency synthesizers, transmit-receive modules, signal processing and system design proposals. The system provides a proposal of frequency prescience; the proposal adopts technology of a constant temperature reference crystal oscillator and a phase-locked loop (PLL) to realize the output of a smaller stepping frequency signal; a mater controller can control the PLL according to a measurement process; VCO output frequency is set to a required frequency point so that the frequency is not needed to be measured in the process of measuring a Q value; and the proposal can accurately measure the Q value of the resonant cavity under the conditions of on-load and no-load. The system eliminates a frequency measurement module, greatly reduces the technical difficulty of the system and reduces the cost.

The invention relates to a method for calibrating the geometrical parameter error of an industrial robot based on a two-step method. A calibration coordinate system is established and comprises a measuring coordinate system and a constraint coordinate system, an error model is established according to the interconversion relationship between a robot connecting rod coordinate system and the calibration coordinate system, and thus the preliminary calibration result of a conversion matrix between the robot connecting rod coordinate system and the calibration coordinate system is obtained; and then the preliminary calibration result is utilized to establish an error correction model including the robot connecting rod geometrical parameter error and the conversion matrix error between the robotconnecting rod coordinate system and the calibration coordinate system according to a differential perturbation method, the corrected robot geometrical parameter error is obtained, and the calibration method is simple and precise.

The invention relates to a method for calculating sensitivity of wind power plant reactive power on voltage based on a perturbation method and belongs to the technical field of automatic voltage control of a power system. The method comprises the following steps of: identifying the equivalent impedance of an external power grid accessing to the wind power plant according to the sensitivity of reactive power at a wind power plant grid-connected point on the voltage of the wind power plant through the perturbation method, and forming a complete power network together with a power network in the wind power plant; combining real-time measurement in the wind power plant to form a jacobian matrix, and calculating to obtain the sensitivity matrix of the reactive powers among the nodes in the wind power plant on the voltage; and finally, checking the calculation result by using the obtained sensitivity of the reactive power on the voltage through the perturbation method, if not, identifying the equivalent impedance of the external power grid again, and calculating the sensitivity matrix of the reactive power on the voltage until the sensitivity matrix passes the check. According to the method, the high-accuracy sensitivity matrix of the reactive power on the voltage is obtained finally and is used for voltage control in the wind power plant.

The invention relates to a multi-group section perturbation method for uncertainty analysis of reactor physics calculation. The multi-group section perturbation method comprises the following steps: (1), on the basis of ENDF/B, making a multi-group section database and a point-by-point section database at different temperatures by using a nuclear database section processing program NJOY, and making the point-by-point section database in a resonant reaction channel at a resonant energy section into an ultra-fine-group database according to the equal rib width; (2), perturbing the point-by-point section database in the energy section corresponding to a certain energy group in a certain reaction channel so as to obtain a perturbed point-by-point section database; (3), strictly transferring perturbation of the point-by-point section database into the multi-group section database by using a linear and nonlinear perturbation transferring method; and (4), reconstructing by adopting a reaction channel section self-consistency principle to obtain a perturbed multi-group section database. According to the invention, the section of a basic reaction channel can be finely sampled; approximate treatment in the multi-group section perturbation process can also be reduced; and thus, a precise multi-group section sample can be obtained.

The invention relates to a boost phase generalized standard miss distance analysis guidance method. The method comprises steps that 1, boost phase guidance problem modeling is carried out, including standard ballistic movement modeling, guidance correction first-order perturbation modeling and terminal constraint modeling; 2, boost phase standard ballistic regular perturbation solution modeling is carried out; 3, boost phase standard ballistic zero-order item analysis solution on the basis of regular perturbation is carried out; 4, boost phase standard ballistic first-order item analysis solution on the basis of regular perturbation is carried out; and 5, boost phase optimal guidance instruction solution on the basis of the standard miss distance is carried out. Through the method, zero-incidence is taken as boost phase ballistic standard control, analysis solution is carried out by employing a regular perturbation method, and thereby an analyzed standard miss distance is acquired; an optimal control method is employed to solve a guidance instruction of the correction standard miss distance, and thereby a non-linear analysis optimal guidance method satisfying boost phase task demands is acquired.

The invention relates to a photovoltaic energy storage inverter off-grid MPPT perturbation method. The method comprises the steps that: an independent power loop connected with a photovoltaic panel to form a photovoltaic loop is set, and an independent charge and discharge loop connected with a battery to form a charge loop and a discharge loop is set; the voltage of a bus is detected; when the voltage of the bus is larger than the upper limit of a control reference voltage of an off-grid system, a photovoltaic energy storage inverter stops the MPPT control over the photovoltaic panel, the voltage of the bus is stabilized to the control reference voltage of the off-grid system, and the discharge loop of the battery is switched off; when the voltage of the bus is lower than the lower limit of the control reference voltage of the off-grid system, the photovoltaic energy storage inverter starts the MPPT control over the photovoltaic panel, the PV voltage of the photovoltaic panel is controlled to a photovoltaic maximum power point, and the battery is controlled by the discharge loop to carry out discharging; or else, the off-grid system maintains the current work state. By applying the method, the photovoltaic off-grid application power configuration restriction and the photovoltaic utilization rate are greatly improved, and the photovoltaic application stability in a district without a power grid is realized.

Methods and system are disclosed for planning and optimizing plans of a value chain in response to events and exceptions in the value chain with minimal perturbations to the existing plan. When an event or an exception occurs, potential solutions are constructed and evaluated. The potential solutions respect the business process constraints and temporal constraints on transactions, and the true dynamic capacity constraints in the value chain. The impact of the potential solutions on finance and on the existing plan is evaluated. The solution with maximum profit and minimum perturbation to the existing plan is selected and executed. Techniques of achieving the above goals are described.

A method, apparatus for and a device manufactured by the same, for printing a microlithographic pattern with high fidelity and resolution using simultaneously optimized illuminator and pupil filters having semi-continuous transmission profiles. The optimization can be further improved if the illuminator and pupil filters are polarization selective. The optimization method becomes a linear programming problem and uses a set of relevant features in the merit function. With a suitably chosen merit function and a representative feature set both neutral printing without long-range proximity effects and good resolution of small features can be achieved. With only short-range proximity effects OPC correction is simple and can be done in real time using a perturbation method.

The invention relates to the technical field of solution parameter measurement and relates to a system for measuring a solution concentration by using a perturbation method. The system comprises a microwave resonant cavity sensor, a wave detector, a voltage-controlled oscillator, a frequency tracking module, a frequency measuring module and a main control processing module, wherein frequency modulated signals generated by the voltage-controlled oscillator under the control of the main control processing module are divided into two ways; one way is mixed with local oscillator signals so as to generate difference frequency signals; the other way is led into a waveguide and is transmitted and coupled by the waveguide to be coupled into a resonant cavity; reflecting signal inside the resonant cavity enters the wave detector through a circulator; modulating signals output from the wave detector are transmitted into the frequency tracking module; the frequency tracking module comprises an amplitude discriminating module and a phase discriminating module; the main control processing module is used for controlling the carrier frequency of the voltage-controlled oscillator; the output of the frequency measuring module is accessed to the main control processing module; and the main control processing module obtains the corresponding relationship between a frequency offset and a solution concentration. The system can realize accurate and real-time measurement to the solution concentration.

The invention provides an MPPT control method used for a photovoltaic cell. A genetic algorithm GA and a variable acceleration perturbation method are combined to conduct MPPT tracking on the photovoltaic cell, and the largest power point is precisely tracked. In the MPPT control method, according to a photovoltaic array output characteristic curve, sectional perturbation is conducted on the photovoltaic battery, according to the value of a voltage change amount dU, an appropriate step length scale factor and a perturbation step length are chosen, according to the value of the corresponding current change amount and the ratio of the corresponding current change amount and the voltage change amount, the perturbation direction is determined, and through a mathematical expression, the accelerating process of the variable acceleration perturbation method is proved; to further improve the tracking precision and reduce the tracking time of a system, the genetic algorithm is introduced, which is used for establishing an initial search duration; the simulation shows that by using the genetic algorithm and the variable acceleration perturbation method to conduct MPPT tracking on the photovoltaic cell, the system stability and the adaptive capacity for the environment can be improved, and the fluctuation near the largest power point is reduced.

The invention discloses a measuring system and a measuring method for thickness of a water film on an inner wall of a humidity sensor by adopting a microwave perturbation method. The measuring system comprises a signal processing controller, a sweep frequency signal source, an isolator, a power divider, a circulator, a microwave measurement resonant cavity, a resonant frequency scanning module, a pressure gage and a thermometer. The measuring method comprises the following steps: measuring resonant frequency of the microwave measurement resonant cavity under TE111 mode; calculating the resonant frequency of the microwave measurement resonant cavity under TE111 mode without the water film; calculating resonant frequency shift caused by the water film; solving the thickness of the water film on the inner wall of the humidity sensor under TE111 mode. The measuring system provided by the invention works on the basis of the TE111 mode of the cylindrical waveguide resonant cavity, is used for quickly and accurately measuring the thickness of the water film on the inner wall of the humidity sensor and brings convenience in eliminating the measuring error of the humidity measuring result caused by the thickness of the water film and increasing the humidity measuring precision.

The invention discloses a strap-down inertial navigation system which compensates the coning error and the sculling error by adopting a method of singular perturbation. The strap-down inertial navigation system is characterized in that a singular perturbation model for compensating the coning error is embedded between an inertial measurement unit and an attitude calculation unit; and a singular perturbation model for compensating the sculling error is embedded between the inertial measurement unit and the navigation calculation unit. The compensation is a perturbation process in which the movement of a carrier changes in a sampling period T and utilizes the actual output value of an inertial unit at a starting sampling point to establish a forcing singular perturbation model. According to the forcing singular perturbation model, the coning error and the sculling error are compensated, and the clock diagram of attitude update and the amount of speed update in the sampling period are obtained. Through adjustment of the amounts of the attitude update and the speed update with close-to-precision variable parameters, the requirement for increasing the algorithmic precision of the calculation units of the strap-down inertial navigation system is met.

The invention discloses a distribution network reliability assessment method. Through element reliability modeling, load modeling, system state selection, system state analysis, and reliability indexes, reliability of a distribution network is calculated, and reliability of the distribution network is effectively assessed. The method comprises: using an equivalent model of elements based on frequency and duration as foundation of element reliability modeling; using a bisection method clustering method to establish a load model, using a quick sort and clustering analysis method to establish a corresponding load model; using a state duration sampling method to determine element state and state duration time of elements or subsystems in given time, to obtain state and state duration time of a system, as system state selection; using an optimal load shedding model based on DC power flow as system sate analysis; reliability index comprehensive assessment including system severity index SI, system cut-down electricity quantity index BPECI calculation and parameter reliability sensitivity, and through a parameter perturbation method, finding an element which has high influence on system reliability.

The invention relates to a storm scale ensemble forecast perturbation method. Observation data analysis, assimilation and numerical simulation are used as major measures; an ensemble forecast method is combined with severe convection weather forecast; and by aiming at the essential differences of the global medium-range ensemble forecast and the storm scale severe convection ensemble forecast, the final goal of building a storm scale ensemble forecast system which is applicable to various kinds of storm systems and constructs the perturbation scheme in a self-adaptive way according to the real-time developed severe convection system features is achieved. The method has the beneficial effects that through a variational assimilation ensemble, the ensemble perturbation realizes the physical and power harmony; the ensemble dispersion degree of the boundary layer mode variable is improved by a random physical harmony method; through self-adaptive selection on perturbation variables sensitive to the real-time developed storm system, the variable with the most obvious influence and the highest sensitivity on the storm development is selected for perturbation; high pertinence is realized; and the ensemble dispersion degree is also improved.

The invention discloses an improved random perturbation method on the basis of a repetition frequency structure vibration characteristic value of an agent model. The method comprises the following steps: firstly, carrying out perturbation analysis on the characteristic value of a repetition frequency structure, and obtaining a matrix equation in regard to the first-order perturbation amount of the free vibration characteristic value of an original repetition frequency structure after parameters including the rigidity, the quality and the like of the repetition frequency structure are subjected to disturbance and change; and then, on the basis of a polynomial chaos expansion method, constructing an agent model in regard to the first-order perturbation amount of a repetition frequency characteristic value; and combining a perturbation method with an agent model technology on the basis of the polynomial chaos expansion, putting forward an improved approximate calculation method of the free vibration characteristic value of the repetition frequency structure, and further obtaining the expressions of a mean value and a variance under the parameter disturbance situation of the repetition frequency structure characteristic value on the basis of the approximate calculation method. The improved random perturbation method solves the problem in the traditional perturbation method that the statistical characteristics of the traditional perturbation method can not be further researched since the first-order perturbation amount of the repetition frequency structure characteristic value can not be expressed by an explicit expression.

The invention discloses an elastic vibration calculation method of a rotating annular periodic structure. The method comprises the following steps: establishing a dynamic model under a follow-up coordinate system; solving a characteristic value of the smooth circular ring; solving a first-order perturbation characteristic value of the annular periodic structure according to a perturbation method;judging the combination relation between the vibration wave number and the discrete support number by means of the operation property of a trigonometric function, and then calculating the characteristic value of the annular periodic structure in a classified manner; judging modal characteristics and power stability according to the obtained characteristic values of the annular periodic structure;the coupling coefficient of the annular periodic structure is solved, and the instability rule of the combination is revealed. The defect that an existing elastic vibration analysis technology is onlylimited to a static or fixed-axis rotating structure is overcome, and therefore the calculation result can better meet the engineering requirement.

The present invention discloses a SIW-based portable liquid dielectric constant measurement system. The system uses a traditional resonant cavity perturbation method as a measurement method and extracts the dielectric constant information of the liquid through a phase-locked loop circuit in connection with a feedback voltage-controlled oscillator based on a substrate integrated waveguide SIW resonator, wherein the SIW resonator places the to-be-measured liquid by inserting a quartz transistor in the middle; the relationship between the oscillation frequency deviation and the dielectric constant is extracted based on the feedback voltage-controlled oscillator in connection with the SIW; finally, the deviation of the oscillation frequency is converted into the voltage deviation through the phase-locked loop circuit, thereby measuring the information of the dielectric constant by simply measuring the voltage signal. Compared with the existing resonant cavity measurement technology that the dielectric constant can be only measured by depending on a vector network analyzer, the SIW-based portable liquid dielectric constant measurement system in the invention eliminates the dependence onlarge experimental equipment under the premise of ensuring accuracy and greatly reduces the cost of measurement.

The invention discloses a hoist spindle reliability analysis, calculation and evaluation method. The method comprises the following steps: S1, strain parameters of the hoist during one hoisting process are detected; S2, cyclic principal stress and cyclic shear stress applied to a drum wheel disc are obtained through the strain parameters; S3, the joint force for a force node is analyzed, torques when the drum wheel disc acts on two load action points of the hoist spindle and a torque when a motor acts on the hoist spindle are analyzed; and S4, a spindle flexural torque diagram and a torque diagram for the hoist spindle are obtained, a distortion energy density criterion for a dangerous section strength formula: a square root of (sigma<2>+3tau<2>)<[sigma] serves as a basis for spindle reliability design, and reliability calculation and evaluation are carried out. According to the hoist spindle reliability analysis, calculation and evaluation method disclosed by the invention, a perturbation method is adopted for reliability design, uncertainty of the load is considered, a reliability index is easy to solve, and more practical value is provided for reliability analysis on the hoist spindle.

The invention discloses a global difference method based non-uniform temperature field thermal modal sensitivity analysis method. The method includes: using an intermediate function to represent a relation between a material parameter and a temperature, for affecting a structural dynamic characteristic, defining an intermediate function coefficient as an intermediate variable, and using the intermediate variable as an initial parameter of sensitivity calculation; establishing a structural finite element analysis model, and calculating a thermal modal parameter; acquiring a new material parameter value through a perturbation method, performing structural thermal modal analysis, solving the thermal modal frequency, calculating an approximate derivative of the thermal modal frequency for theinitial parameter according to a difference format of the global difference method, and acquiring the sensitivity. The material parameter associated with the temperature field is fitted into a linearfunction curve, and then sensitivity analysis of the material parameter filed in thermal modal under the non-uniform temperature field is converted into sensitivity analysis of the intermediate function coefficient, and an objective of reducing sensitivity parameters to be analyzed can be achieved. Parameter iteration difference calculation can be achieved on the basis of MATLAB programming, and the calculation efficiency is improved.

The invention relates to an analytical guidance method for a standard control miss distance of a terminal guidance section. The analytical guidance method comprises the following steps: firstly, modeling the terminal guidance section; secondly, dividing a standard control trajectory at the terminal guidance section into a zero-order standard control trajectory and a first-order standard control trajectory according to a canonical perturbation theory; thirdly, performing analytic solution on a zero order item of the standard control trajectory at the terminal guidance section; fourthly, performing analytic solution on a first order item of the standard control trajectory at the terminal guidance section; and fifthly, acquiring a complete analytical solution of the standard control trajectory, and calculating a guidance command. The analytical guidance method disclosed by the invention has the advantages that firstly, an idea of taking a zero attack angle as standard control over the terminal guidance section of a homing missile is put forward, and a motion equation of the standard control trajectory is simplified; in addition, an attack angle required by guided correction is enabled to be located near zero, and speed loss brought by the guided correction is reduced; secondly, analytic solution is performed on a longitudinal trajectory at the terminal guidance section by adopting a canonical perturbation method, and high-precision analytical solutions of firing range, height, speed and trajectory inclination angle are obtained; and thirdly, a guidance method based on a generalized standard control miss distance is provided, and normal acceleration of the missile is greatly reduced; and meanwhile, the terminal attack angle is enabled to be converged to be zero.

The invention provides a finite element model correction method based on the perturbation method for a complex model under uncertainty, comprising: deducing an iteration form for average and covariance matrixes for under-correction parameters of the complex model; determining complex model correction target average and covariance matrixes; determining initial estimated values of the under-correction parameters of the complex model; calculating a sensitivity matrix and modal frequencies for the under-correction parameters of the complex model through finite element analysis; reading finite element calculation results of the complex model, and calculating an intermediate variable conversion matrix and the covariance matrix; correcting an average and covariance of the under-correction parameters of the complex model to obtain updated parameters; performing cyclic iteration to carry out parameter correction. File reading-writing and data transmission channels are established based on the commercial mathematical software MATLAB and the finite element simulation software NASTRAN; the method is suitable for solving model correction problems where both system parameters of a complex modeland test data present uncertainty, and corrected parameters have high average precision.