48 results about "Time stepping" patented technology

The invention discloses a hypersonic aerocraft leading edge fluid-heat-solid integrated calculation method, and belongs to the field of aerocraft pneumatic calculation. For solving the problem of complex coupling of structure heat transfer and hypersonic speed flow aerodynamic heating, the method avoids the complex data exchange and calculation amount caused by flow field and structure coupling alternate iteration calculation performed within a time domain through a traditional aerodynamic heating/structure heat transfer coupling solving method, the flow field and the structure are adopted asa physical field, and a uniform control equation is adopted. Physical parameters of a fluid and solid interface are defined again, a finite volume method is performed on a full physical field for spatial dispersion, and hidden time iteration is adopted for time stepping. Compared with a coupling algorithm, the method needs no extra data exchange or coupling strategy, the calculation result and anexperiment value are closer, the calculation amount and the grid dependency are smaller, and the better stability and calculation precision are achieved.

The present invention relates to an exercising device with combined stepping and twisting functions comprising a base member, a stepper mechanism mounted on the base member, a stepper assembly pivotably and rotatably secured with respect to the stepper mechanism and base member in a manner that the stepper assembly is capable of performing simultaneously or one at a time stepping and twisting functions through an engaging rotatable mechanism into which the stepper assembly is movably engaged through a linkage means, and a selecting mechanism for selectively activating or deactivating the functions being provided thereto.

The invention relates to a method of optimallying designing a closed-winding permanent magnet brushless DC motor on the basis of differential evolution algorithm and finite element time-stepping method. The method includes: according to the particularity in the closed-winding permanent magnet brushless DC motor, by considering a body and a control part of the motor, using the cost in torque density and unit torque of a system as an optimization target; using constraint conditions such as parallel branch circulation, power factor, efficiency, torque output, fluctuation, heating, structural strength and the like. The method has the advantages that design schemes of each generation are varied, intersected and selected for differential evolution, and a Pareto optimal solution set is updated continuously; in order to ensure design accuracy, the finite element time-stepping method is applied to accurate dynamic simulation computation of the closed-winding permanent magnet brushless DC motor; the reliable and accurate method is provided for the design optimization of the closed-winding permanent magnet brushless DC motor, and the development of the novel motor is quickened.

The invention relates to an electromagnetic scattering simulation method of a one-dimensional conductor rough sea surface and a two-dimensional conductor target. The method comprises the following steps: (1) inputting a power spectral density function of the one-dimensional conductor rough sea surface and a rough sea surface parameter, modeling the one-dimensional conductor rough sea surface to generate a one-dimensional conductor rough sea surface; (2) subdividing the one-dimensional conductor rough sea surface and a two-dimensional infinite long conductor target under the irradiation of an incident wave; (3) incoming a conical wave to the one-dimensional conductor rough sea surface and the two-dimensional infinite long conductor target; (4) according to the boundary conditions in the electromagnetic field, acquiring a time stepping equation of a display format of the incident wave one-dimensional conductor rough sea surface and the two-dimensional infinite long conductor target under the incidence; and (5) solving out a two-dimensional transient far field according to the numerical value of the current response of the target changing along the time. The method disclosed by the invention has the following beneficial effects that the interaction of the rough sea surface and the electromagnetic wave of the target is visually represented; and the composite electromagnetic scattering of the rough sea surface and the target under different wind speeds is simulated.

The present invention relates to a shoe sole for triple-time stepping that includes: a front portion having a front end gently inclined upward, and a bottom portion in even contact with the ground; a rear portion having a second cutout inclined upward at an angle of about 15 to 17° from a rear end of the front portion, and a first cutout inclined upward at an angle of about 15 to 25° from a rear end of the second cutout; a first recess formed upward in a predetermined depth on a boundary portion between the front portion and the second cutout; and a second recess formed upward in a predetermined depth on a boundary portion between the second cutout and the first cutout. The improved shoe sole enables a tri-time stepping on walking to remarkably mitigate a fatigue with a massage effect produced from a proper stimulation of the flow of energy to prevent flat-foot walks and promote metabolism and blood circulation, and disperses the impact force caused by the weight to prevent diseases such as arthritis, back pain, muscle pain, or the like.

The invention discloses a load recovery two-stage optimization method considering wind power connection and used for researching a load recovery decision problem with wind power participation. Firstly, a single time-stepping load recovery problem is subjected to two-stage decoupling, wherein in the first stage, by taking the sum of a weighting load and a wind power output recovery value as the maximum target, a load recovery 0-1 planning model is established; next, in the second stage, by taking the shortest recovery time consumption as the target and by taking the decision variable obtained from the first stage as the initial condition, an alternating current power flow-based nonlinear planning model is established; and finally, each time stepping is solved in sequence to obtain a recovery decision scheme in the full process. By virtue of different time stepping decision idea, an effective recovery decision scheme can be obtained, wind power sequential access is realized and load recovery time consumption is shortened, so that the technical problems in load recovery decision in conditions of relatively large system scale and wind power system participation can be solved.

The invention discloses a method for determining the vibration working stress limit of an aircraft anti-skidding braking control box. the method comprises the following steps: applying vibrating stress on a control box in a stepping manner to determine the vibration working stress limit of the control box, wherein the step size of the vibration stress applied in a stepping manner is 1-5Grms; the state is kept for 5min every time stepping vibration reaches a specified value to reserve time for vibration stress balancing of the control box, and then a test is performed and lasts for 5min, and the total amount of vibration maintaining time in each step is 10min; and obtaining the vibration working stress limit of a sample piece by using the stepping vibration testing method. According to theinvention, a method that working stress is applied to the control box in the testing process is adopted, and a fault vibration value is determined in time by tracking and observing. If the vibration amount value does not satisfy a design requirement, an improvement advice focused on the vibration performance is proposed. If the vibration amount value satisfies the design requirement, the vibration amount value is taken as an initial value of the vibration working stress limit.

The invention discloses a calculation method of a compressible fluid pressure field based on a PIV (Particle Image Velocimetry) technique. The method comprises the steps of selecting a gas state equation, a heat state equation, and a momentum equation and an energy equation in a hydromechanical governing equation set, namely an N-S equation set as a fundamental equation set for calculating the compressible fluid pressure field, performing rearrangement and finite difference processing on the fundamental equation set according to a requirement of a prediction-correction technique, setting an appropriate boundary condition according to a concrete form of a fluid field, and performing time stepping solution on the fundamental equation set by the prediction-correction technique to obtain the pressure field corresponding to a PIV velocity field. The invention further discloses a device for realizing the method. Therefore, a pressure field measurement scheme based on the PIV technique is provided for a compressible fluid; calculation limitation of the existing incompressible fluid pressure field is overcome; and an application scope of a fluid field pressure measurement scheme based on the PIV technique is greatly extended.

The invention discloses a method for estimating distribution of electromagnetism in flying targets made of carbon fiber materials under lightning pulses. The method comprises the following steps of simulating the lightning pulses with an ultra-wide spectrum range by using time domain plane waves; establishing a time domain analysis module of the flying objects made of the carbon fiber materials under the lightning pulses; performing transient far field high-efficiency calculation by using an algorithm of plane wave time domain (PWTD); quickly calculating an impedance matrix of a time stepping time domain volume integral equation MOT by using an equivalent electric dipole modal; solving a time domain matrix equation; and extracting electromagnetism characteristic in a broadband. By the method, only the flying targets made of the carbon fiber materials are dispersed, a free space green function is used, the equation is simple, uneven targets can be analyzed, the calculation precision is quite high, and an unknown quantity is small; and moreover, the equation is solved by a time domain method, and the electromagnetic characteristic of all frequency points in a frequency band can be calculated at one step. Compared with a frequency domain method requiring sweep frequency operation, the method has the advantages that time consumed on solving is greatly shortened.

The invention discloses a ground-penetrating radar forward-modelling method based on FETD and FDTD coupling. The method comprises the following steps: loading a two-dimension model parameter; dividinga ground-penetrating radar numerical simulation region into a model region and an extension region; splitting the model region by adopting an unstructured triangle unit, and splitting the extension region by using a regular grid; setting a measurement point, and loading an excitation source at a location corresponding to the measurement point; setting the components of the electric fields and auxiliary fields of all time before the initialization time step as zero, and updating the auxiliary field according to the FDTD auxiliary field time stepping formula, and updating the electric field according to the FETD main field time stepping formula so as to obtain the electric field value of the measurement point at each time step till to the maximum time step; and obtaining the ground-penetrating radar forward-modelling profile map according to the electric field values of all time steps at each measurement points. The method disclosed by the invention is high in fitting precision and fastin computation.

The invention discloses a simulation method for rapidly extracting transient scattered signals of an electric large-size metal cavity target. The simulation method includes creating a geometric model of the metal cavity target, and performing mesh dissection on the surface of the metal cavity target by a curved-surface triangular unit; determining a time domain integral equation of the metal cavity target; unfolding a surface induced current in the time domain integral equation by a high-order lamination divergence conformal basis function in terms of space and a time and space-time hybrid basis function in terms of time; substituting a surface induced current expression into the time domain integral equation, and testing a time domain electric field integral equation in a discrete form in terms of time and space respectively to acquire a system impedance matrix equation; solving the impedance matrix equation by a time stepping method, determining time domain current distribution on the surface of the conductor target, and acquiring broadband electromagnetic characteristic parameters of the target according to time domain current distribution to complete simulation. The method has the advantages of high simulation accuracy, less time used and low memory consumption, thereby having a broad application prospect.

The invention relates to a vehicle suitable for preventing a driver from accidentally stepping on an accelerator pedal in an emergency braking process and a working method thereof. The vehicle comprises a control system for preventing the driver from accidentally stepping on the accelerator pedal in the emergency braking process, the control system comprises an accelerator pedal sensor used for collecting real-time stepping accelerated speed of the accelerator pedal, and a processor module connected with the accelerator pedal sensor, and two output ends of the processor module are connected with an acceleration control circuit and a brake control circuit inside the vehicle respectively. The vehicle and the working method thereof effectively avoid fatal traffic accidents caused when the new driver accidentally steps on the accelerator pedal when needing emergency braking in emergency circumstances; meanwhile, second stepping sample data can be updated, so that judgment accuracy is improved.

The invention belongs to the related field of coal mining equipment, and particularly designs a hydraulic support linkage self-moving device and a hydraulic support linkage self-moving method. According to the technical scheme, the hydraulic support linkage self-moving device comprises hydraulic supports with horizontal hydraulic pushing rods, cross rods and pushing rods. Three sets of hydraulic supports are arranged side by side, a shovel plate is arranged at the front end of each cross rod, pin lugs are arranged at the rear ends of the cross rods and are connected with the three sets of evenly-distributed pushing rods through pin shafts, and the pushing rods are connected with the horizontal hydraulic pushing rods of the hydraulic supports through pin shafts. The device has the advantages that one set of specially-manufactured sliding public pushing rods is utilized for enabling the three hydraulic supports to be connected in parallel together, cooperation of hydraulic pushing jacks of the hydraulic supports is utilized, the action mode of the pushing rods and a lever is comprehensively utilized, dynamic and in-time stepping forward moving of supporting of three shield supports can be achieved, and after the supports are removed, support-following maintenance can be carried out in time. The potential safety hazard that a connecting part is broken to hurt people, and a steel wire rope is broken to hurt people is thoroughly eliminated, and safe and rapid removing and top plate supporting of the hydraulic supports can be achieved.

The invention discloses a time inversion photoacoustic image reconstruction method based on time domain finite difference. The method comprises the steps: obtaining the scanning data of a photoacoustic image; carrying out the discretization of a sound wave equation, and building a calculation grid of time domain finite difference; building a grid absorption boundary condition of the time domain finite difference according to a unidirectional wave equation; carrying out the time reversal of the photoacoustic signal, and loading the photoacoustic signal to a corresponding receiving position after time reversal; finally carrying out the time stepping of a time domain finite difference formula, calculating a maximum variance norm, stopping the time stepping when the maximum variance norm reaches a minimum value, and outputting a reconstructed image. The method can be used for mediums with uniform and nonuniform sound speeds, is not limited by a scanning mode, achieves the dual focusing of the photoacoustic signal in time and space, can precisely reconstruct the optical absorption distribution of biological tissues, and is great in actual application value.

This invention relates to a novel method for accelerating time integration of the heat equation based on a decomposition of the solution domain into multiple regions, allowing a different discrete time step size in each domain. Domains are coupled at interfaces using a novel formulation for the boundary condition, including a mixed (Robin) condition for the small timestep domain that uses a coupling parameter optimized for stability and accuracy. This algorithm allows many-times speedup for simulation of systems such as additive manufacturing of metals, where fast evolution of the solution field is limited to a small region while the remainder of the domain evolves more slowly.

Disclosed is a series winding type brushless rotor doubly-fed generator analyzing method. The method includes the steps of A, establishing a two-dimensional magnetic field model of a series winding type brushless rotor doubly-fed generator; B, establishing a stator circuit model of the series winding type brushless rotor doubly-fed generator; C, establishing a rotor circuit model of the series winding type brushless rotor doubly-fed generator; D, establishing a mechanical motion model of the series winding type brushless rotor doubly-fed generator; E, establishing a field-circuit-motion coupling module time-stepping module of the series winding type brushless rotor doubly-fed generator and having the same solved according to the two-dimensional magnetic field model, the stator circuit module, the rotor circuit module and the mechanical motion model of the series winding type brushless rotor doubly-fed generator. With the method, influences of multiple nonlinear factors can be integrated, the operation state of an actual series winding type brushless rotor doubly-fed generator is got closer, and accuracy in dynamic analysis of the series winding type brushless rotor doubly-fed generator is improved.

A computer-implemented method of simulating behaviour of a thermodynamic system over time, the thermodynamic system having a state described by collective vectors of position and momentum at any given time and the method comprising a momentum refreshment process, a conservative dynamics process, and an acceptance/rejection process, wherein the momentum refreshment process comprises mixing the collective momentum vector with a noise vector; the conservative dynamics process comprises applying a mollified impulse multiple time stepping conservative dynamics method to a current state, in which process calculations for forces corresponding to more slowly varying energy parts in the thermodynamic system undergo an averaging procedure and are carried out at a larger time step than calculations for forces corresponding to more quickly varying energy parts; and wherein the acceptance/rejection process is based on the system energy and comprises accepting a current state or returning a replacement state.

A computer-implemented method of simulating behaviour of a thermodynamic system over time, the thermodynamic system having potential energy that can be split into more quickly varying parts and more slowly varying parts and having a state described by collective vectors of position and momentum at any given time, the method comprising a momentum refreshment process and a conservative dynamics process, wherein

• • the momentum refreshment process comprises carrying out an operation of mixing the collective momentum vector with a noise vector and carrying out an acceptance/rejection operation;
  • the conservative dynamics process comprises applying a multiple time stepping conservative dynamics operation to a current state, in which operation calculations for forces corresponding to more slowly varying energy parts in the thermodynamic system undergo an averaging procedure and are carried out at a larger time step than calculations for forces corresponding to more quickly varying energy parts; and carrying out an acceptance/rejection operation; wherein
  • the acceptance/rejection operations are based on an approximation of the system energy expressed using shadow Hamiltonians and comprise accepting a current state or returning a replacement state.