57 results about "Numerical methodology" patented technology

A method for modeling diffraction includes constructing a theoretical model of the subject. A numerical method is then used to predict the output field that is created when an incident field is diffracted by the subject. The numerical method begins by computing the output field at the upper boundary of the substrate and then iterates upward through each of the subject's layers. Structurally simple layers are evaluated directly. More complex layers are discretized into slices. A finite difference scheme is performed for these layers using a recursive expansion of the field-current ratio that starts (or has a base case) at the lowermost slice. The combined evaluation, through all layers, creates a scattering matrix that is evaluated to determine the output field for the subject.

A financial methodology for the analysis of events' impact on media coverage and business, and predictive indications of movements of stock prices (or other financial instruments) triggered by media and business impact is described. The methodology is based on a numerical approach suitable for processing by a computer. It takes into account data outside the traditional realm of finance, such as public sensitivity to certain classes of events, and the correlation between media coverage and stock price performance during the course of an event.

The invention belongs to the field of computational fluid mechanics, in particular to a numerical method for solving a two-dimensional Riemannian problem, and is applied to solve an Euler equation and perform the numerical simulation of subsonic non-viscous stream. By the numerical method, the Euler equation on an Euler plane is transformed to a stream function plane; in a two-dimensional Cartesian grid, the Riemannian problem of a translational stream line and the Riemannian problem along the stream line are solved, so that the error of a numerical solution is reduced.

The invention discloses a method for solving a numerical value of a dispersion curve in a sonic sensor. A method for solving a numerical value of a dispersion curve in a real-wave number field and a complex-wave number field is used for solving the frequency of a dispersion equation in the real-wave number field and the complex-wave number field and the solution of a wave number by utilizing the convergence of the module value of the dispersion equation near a zero point. The method comprises the following steps: determining the form of a scanning unit according to a wave number solving space; comparing and finding out the minimal value point of the module value of the dispersion equation in a corresponding space by utilizing the scanning unit; and judging whether the minimal value point is the zero point or not by utilizing the convergence of the module value of the dispersion equation near the zero point. According to the invention, the problem of being difficult to solve the numerical value of the dispersion equation in the real-wave number field and the complex-wave number field can be effectively solved; the method can be used for solving dispersion equations in all kinds of wave propagation problems; and the method is applied to wave propagation and analysis in multiple sensor models.

The invention provides a numerical method simulating ultrasonic cavity dynamics behaviors; the method comprises the following steps: 1, building control equations including an ultrasonic field conservation of mass equation and a momentum equation; 2, building an ultrasonic radiation force equation; 3, substituting the ultrasonic radiation force equation into the momentum equation, and nondimensionalizing the control equation; 4, resolving the nondimensionalized control equation, extracting needed flow field data, and thus simulating the ultrasonic cavity dynamics behavior. The numerical method can simulate ultrasonic cavity form changes, wherein the simulated ultrasonic cavity form change has small error with the real ultrasonic cavity form change, thus capturing ultrasonic cavity transient evolution rules and cavity collapse characteristics.

The invention relates to a numerical method for simulating wingtip vortex flow of an aircraft. According to the characteristics of incompressible flow, two different forms of forces are added into a momentum equation to improve the precision of numerical simulation of one type of flow fields giving priority to vertical motion. The two forms of forces include a corkscrew force of vorticity in a gradient direction of change and a viscous dissipation force of the vorticity in the gradient direction of change. According to the method, integral computation on the corkscrew force in the gradient direction of change of the vorticity in a computational grid is transformed flux calculation on a force on the boundary of the computational grid, so that the spatial dispersion of the force can have a high-order-accuracy format; and simultaneously, the viscous dissipation force in the gradient direction of change of the vorticity is maintained by a source item of the momentum equation, thereby improving the astringency and stability of a numerical solution. As the forces adopt different amplification coefficients, the accuracy of the vorticity can be further maintained, and the vertical motion of wingtip vortex can be simulated more accurately.

The present invention relates a numerical method to simulate the incompressible wing-tip vortex flows. This method is called Vorticity-Refinement, which refines the added vorticity as two different forms of force multiplied by two different factors to counteract the numerical diffusions in the numerical solutions by utilizing the high-order spatial discretization and improving the stability and convergence of the governing equations for incompressible flows.

The invention discloses a high-precision self-adaptive finite volume-finite difference coupling numerical simulation method, and belongs to the field of multi-substance coupling effect high-precision numerical simulation. According to the method, adaptive coupling of two numerical methods of finite volume and finite difference can be realized, different numerical formats are selected for calculation at different positions of a calculation domain according to an adaptive algorithm judgment rule, and different high-precision algorithm calculation areas are coupled by adopting an adaptive algorithm coupling method, so that the calculation accuracy is improved. According to the method, the high-resolution shock wave discontinuous capture effect of the high-order finite difference method can be obtained, the inherent good conservation characteristic of the finite volume method can be considered, the accuracy of a numerical simulation prediction result can be remarkably improved, and then the engineering technical problem related to the high-precision numerical simulation field can be effectively predicted. The high-precision numerical simulation field comprises the fields of high-speed/ultrahigh-speed warhead penetration and protection, underwater explosion, bubble dynamics, aerospace and mechanical engineering.

The invention discloses a numerical method for optimizing the performance of an organic Rankine cycle system. The numerical method comprises the steps of optimizing cycle parameters to improve the system performance, and optimizing cycle working medium components to improve the system performance. According to the step for optimizing the cycle parameters to improve the system performance, parameters which have great influence on the system performance are selected, sensitivity analysis is conducted on the parameters, a sensitivity change interval serves as an independent variable change interval, and the system performance is optimized through an optimization algorithm; and according to the step for optimizing the cycle working medium components to improve the system performance, control over the working medium components is achieved by optimizing the mass flow/molar flow of all the components in a working medium, the mass flow/molar flow of all the components of the working medium serves as an independent variable, a system performance evaluation index serves as a dependent variable, and the system performance is optimized through an optimization algorithm. According to the numerical method for optimizing the performance of the organic Rankine cycle system provided by the invention, optimization work of system node parameters and working medium components can be rapidly completed, the system design optimization process is simplified, and the participation degree of technicians in the optimization process is reduced.

The invention relates to a numerical method for simulating a ship propeller wake field. The numerical simulation accuracy of a type of flow fields predominant in vortex motion is improved by forces of two different forms in a momentum equation according to the feature of incompressible flows. The forces of two different forms include a spiral force whose vorticity is in a variable gradient direction and a viscous dissipation force whose vorticity is in the variable gradient direction. The method converts an integral calculation of the spiral force in the calculation grid, of which the vorticity is in the variable gradient direction, into a flux calculation of a force on the boundary of the calculation grid, so that the spatial discretization of the force has a format of higher order accuracy. Meanwhile, the source item of the momentum equation maintains the viscous dissipation force whose vorticity is in the variable gradient direction, so as to improve the convergence and stability of numerical solution. The two forces have different amplification coefficients, so that the accuracy of vorticity can be further maintained, and as a result, the vortex motion of the ship propeller wake field is simulated more accurately.

The invention discloses a method for condensing FETI engineering numerical values based on regional decomposition. The method comprises the steps of solving a generalized flexibility matrix and a boundary flexibility matrix through constructing a rigid matrix only related to the boundary freedom degree of a floating sub-domain and a rigid body modal matrix of the rigid matrix. The formed new 'hat' matrix can fully utilize and maintain the sparsity of the floating sub-domain rigid matrix, and the order of the new 'hat' matrix is equal to the number of floating sub-domain boundary degrees of freedom and is far smaller than the scale of the original 'hat' matrix, so that the storage space is greatly reduced, and the triangular decomposition solving efficiency of the generalized stiffness matrix is improved; and the calculation of the local flexibility matrix becomes economical and feasible. Meanwhile, an intermediate result of the new 'hat' matrix calculation just provides a Dirichlet preprocessor with a better convergence characteristic for PCPG iterative solution of a frame equation set.

The invention provides a parallel configurable intelligent optimization method based on a collaborative optimization strategy, and the method comprises the following steps: 1, building an MDO optimization problem according to requirements, and determining an optimization model and a system-level optimization model; 2, determining parameters of an adaptive hybrid optimization method according to aspecific optimization problem; 3, converting and optimizing an objective function based on a penalty function method; 4, distributing an initial value to the subsystem level by the system level, carrying out subsystem level optimization by the subsystem by adopting a conventional numerical method, and returning an optimization result of the subsystem level to the system level; 5, comparing to obtain the difference between the subject optimization solution and the system-level optimization solution, calculating a penalty factor, and reconstructing a system-level optimization model; 6, performing system-level optimization coordination and solution by adopting a hybrid intelligent method; 7, judging convergence. According to the invention, a complex product engineering digitization and networking design optimization system is perfected, the application space of collaborative optimization and intelligent optimization methods in the field of design optimization is expanded, and the design quality and design efficiency of products are effectively improved.

The invention discloses a nanostructure extinction characteristic simulation method based on a moment method in combination with an adaptive cross approximation fast algorithm. According to the method, a moment method in an integral equation method is adopted for solving, and compared with a traditional numerical method such as a finite element method based on a differential equation method, dispersion errors do not exist, and the accuracy is high. According to the method, the extinction characteristic of the large-scale nanostructure can be solved by combining the adaptive cross approximation fast algorithm on the basis of the moment method, transplantation can be conveniently carried out under different background media, and the application range is wide.

The invention discloses a nonlinear energy trap optimal rigidity solving method based on a platform phenomenon, belongs to the technical field of structure control. According to the method, with combination of the actual situation of civil engineering, on the premise of small initial conditions, multi-scale analysis is carried out on a two-degree-of-freedom system composed of a linear main structure and a cubic rigidity nonlinear energy trap, a "platform" phenomenon in a slow-varying equation is observed, so that an excitation amplitude interval in which the damper can generate effective target energy transfer under the condition that system parameters are fixed is obtained; an analytical solution of the optimal design rigidity of the nonlinear damper is derived through formulas of the upper limit and the lower limit of the interval, and through inspection of a numerical method, the design value has outstanding advantages in the aspects of the vibration reduction effect and robustness.The obtained optimized stiffness analytical solution gets rid of constraints on initial conditions, is applied to the design of nonlinear dampers, is simple in actual operation and good in optimization effect, and has great application value and development prospect.

The invention relates to the field of materials, and provides a solid structure smooth particle dynamics modeling method. The method comprises the steps: discretizing a planar solid structure into SPHparticles, wherein each particle carries at least one kind of same physical information; deformation occurs at a spatial point xi, and calculating a correction mode of a smooth function derivative atthe spatial point xi; then calculating the deformation of the spatial point xi; and finally, in a deformation state, calculating the deformation gradient at the spatial point xi. According to the invention, a smooth function correction method and a complete Lagrange SPH method are combined to obtain the correction mode of the smooth function derivative as an integral kernel, so the first-order completeness of the numerical method is ensured, the boundary calculation accuracy is improved, the stretching instability phenomenon is eliminated, the calculation time is greatly saved, and the boundary defects and instability of the traditional SPH are overcome.