489 results about "Partial differential equation" patented technology

A multimedia content delivery system includes a server apparatus (100) for delivering graphical information across a network (30) to a client device (200). An environment engine (150) controls a virtual environment responsive to user commands. An object transformation unit (400, 405) transforms original object data (310) relating to a plurality of objects into compressed object data (350). A data management unit (120) transmits the compressed object data to the client device (200). The compressed object data (350) is decompressed and rendered by the client device (200) to output images to represent the virtual environment on a visual display device. Server-side and client side I / O handler units (130, 230) provide the user commands from the client device (200). The compressed object data (360) may comprise coefficients of a solution to a partial differential equation. Methods and apparatus are described relating to polygon-based object geometry (510) and pixel-based image files (600) which are transformed and regenerated using coefficients (540, 606) of a solution to a partial differential equation.

The invention relates to a method of performing an oilfield operation of an oilfield having at least one wellsite, each wellsite having a wellbore penetrating a subterranean formation for extracting fluid from an underground reservoir therein. The method includes determining a time-step for simulating the reservoir using a reservoir model, the reservoir being represented as a plurality of gridded cells and being modeled as a multi-phase system using a plurality of partial differential equations, calculating a plurality of Courant-Friedrichs-Lewy (CFL) conditions of the reservoir model corresponding to the time-step, the plurality of CFL conditions being calculated for each of the plurality of gridded cells and comprising a temperature CFL condition, a composition CFL condition, and a saturation CFL condition calculated concurrently, simulating a first cell of the plurality of gridded cells using the reservoir model with an Implicit Pressure, Explicit Saturations (IMPES) system to obtain a first simulation result, the first cell having no CFL condition of the plurality of CFL conditions with a value greater than one, and simulating a second cell of the plurality of gridded cells using the reservoir model with a Fully Implicit Method (FIM) system to obtain a second simulation result, the second cell having at least one CFL condition of the plurality of CFL conditions with a value greater than one, and performing the oilfield operation based on the first and second simulation results.

The invention discloses a design method for a boundary control law of a flexible mechanical arm-based partial differential equation model. The design method comprises five steps of: 1, establishing a double-link flexible mechanical arm dynamic model; 2, decomposing the double-link flexible mechanical arm dynamic model; 3, designing an adaptive boundary control law; 4, verifying the global stability of a closed-loop system; and 5, finishing the design. By the design method, a condition that the frequency of joint angle movement is different from that of elastic oscillation is considered first, and a partial differential dynamic model is decomposed into a fast subsystem and a slow subsystem by a singular perturbation method; a slow adaptive boundary control law is designed on the slow subsystem, so that a joint motor can move to an expected position; a fast adaptive boundary control law is designed on the fast subsystem to inhibit the elastic oscillation; and the fast and slow subsystems form a hybrid controller to control the joint angle and oscillation of a double-link flexible mechanical arm and ensure the global stability of the closed-loop system.

A level set polarization SAR image segmentation method based on polarization characteristic decomposition, belonging to the radar remote sensing technology or the image processing technology. In the invention, a polarization characteristic vector v which is composed of three polarization characteristics: H, alpha and A is obtained by the polarization characteristic decomposition of each pixel point of the original polarization SAR image; the polarization characteristic vectors v of all the pixel points are combined into a polarization characteristic matrix omega so as to convert the segmentation problem of the polarization SAR image from data space to polarization characteristic vector space; and the condition that the characteristic vector definition is suitable for energy functional of the polarization SAR image segmentation is utilized and a level set method is adopted to realize the numerical value solution of partial differential equation, thus realizing the polarization SAR image segmentation. The method provided by the invention takes full use of the polarization information of the polarization SAR image; therefore, the image edge obtained by segmentation is relatively complete so that the local characteristic is maintained better, the robustness for noise is stronger, the stability of the arithmetic is higher and the segmentation result is accurate; and the invention reduces the complexity of data and can effectively improve the image segmentation speed.

The invention discloses a bedding surface based on a level set and a method for generating a geologic body, which is applied to a system for geologic modeling, simulation and analysis. The method is characterized by comprising the steps: a sectional model is built, and a three-dimensional computational grid is formed on the basis of the sectional model; a scalar field used for calculating the flowing speed of a computational interface is formed in each bedding surface according to bedding surface discrete points; an initial level set is built according to the bedding surface discrete points; numerical solutions to the partial differential equation about the flowing of the interface are carried out in the three-dimensional grid, which causes the level set to update so as to lead to the evolution of the moveable interface, finally drawing near to a target bedding surface; a final strata surface is obtained by tracing a zero contour surface; the level set corresponding to each bedding surface is utilized to realize the description of the boundary and interior of the geologic body. The invention can realize the automatic reconstruction of bedding surfaces and geologic bodies of a plurality of faults at complicated geologic states, such as overthrust faults, mushroom bodies, salt domes, lenticular bodies, and the like, and effectively improve the generating efficiency and precision of complicated geologic structure models.

Fast reconstruction methods are provided for 3D time-of-flight (TOF) positron emission tomography (PET), based on 2D data re-binning. Starting from pre-corrected 3D TOF data, a re-binning algorithm estimates for each transaxial slice the 2D TOF sinogram. The re-binned sinograms can then be reconstructed using any algorithm for 2D TOF reconstruction. A TOF-FORE (Fourier re-binning of TOF data) algorithm is provided as an approximate re-binning algorithm obtained by extending the Fourier re-binning method for non-TOF data. In addition, two partial differential equations are identified that must be satisfied by consistent 3D TOF data, and are used to derive exact re-binning algorithms and to characterize the degree of the approximation in TOF-FORE. Numerical simulations demonstrate that TOF-FORE is more accurate than two different TOF extensions of the single-slice re-binning method, and suggest that TOF-FORE will be a valuable tool for practical TOF PET in the range of axial apertures and time resolutions typical of current scanners.

The subject invention pertains to a method of image intensity correction. The subject invention can utilize extrapolation for image intensity correction. The use of extrapolation can reduce the artifacts during intensity correction as compared to traditional methods of intensity correction. The extrapolation can be combined with, for example, homomorphic filtering methods, parametric estimation techniques, wavelet based method, and / or Gaussian smooth method, in order to reduce the artifacts generated by these methods and improve the quality of correction. The implementation of image extrapolation in accordance with a specific embodiment can utilize closest point method. The subject method can also use adaptive smoothing for image intensity correction. In an embodiment, the use of gradient weighted smoothing method can reduce, or eliminate, over-smoothing of bright spot regions. In a specific embodiment, the subject method can utilize gradient weighted partial differential equation (PDE) smoothing.

The invention discloses a reverse design method for an impeller of a centrifugal pump, which comprises the following steps: according to a given impeller axial plane, a blade in a three-dimensional space can be actually expressed as X=X(z(u, v), r(u, v), theta(u, v)), the (z(u, v), r(u, v)) has been determined when a streamline of the impeller axial plane is given, and the space modeling of the blade can be determined by determining the theta(u, v) on the impeller axial plane. The reverse design method is characterized in that the reverse design method transforms a geometric design problem of the blade of the centrifugal pump into a boundary value problem of a partial differential equation to solve under the condition of the given impeller axial plane of the centrifugal pump. The reverse design method overcomes a lot of disadvantages such as the definition and modification of geometrical shape of the blade in the prior design method, can realize the parametric design of the blade, overcome the defects existing when a fussy two-dimensional form drawing is used for showing three-dimensional twisted blades in the prior method, can closely combine the hydraulic design of hydraulic machinery, three-dimensional solid modeling and the CFD analysis of flow field, and realize the quick and accurate solving of the reverse problem of the blade.

A geospatial modeling system may include a geospatial data storage device, and a processor cooperating with the geospatial data storage device for selectively inpainting data into at least one void in geospatial model data using a partial differential equation (PDE) algorithm and an exemplar algorithm.

The subject invention pertains to a method of image intensity correction. The subject invention can utilize extrapolation for image intensity correction. The use of extrapolation can reduce the artifacts during intensity correction as compared to traditional methods of intensity correction. The extrapolation can be combined with, for example, homomorphic filtering methods, parametric estimation techniques, wavelet based method, and / or Gaussian smooth method, in order to reduce the artifacts generated by these methods and improve the quality of correction. The implementation of image extrapolation in accordance with a specific embodiment can utilize closest point method. The subject method can also use adaptive smoothing for image intensity correction. In an embodiment, the use of gradient weighted smoothing method can reduce, or eliminate, over-smoothing of bright spot regions. In a specific embodiment, the subject method can utilize gradient weighted partial differential equation (PDE) smoothing.

The invention relates to a joint estimation method of a state of charge (SOC) and a state of health (SOH) of a power battery system based on an electrochemical model. The method comprises the steps of establishing a pseudo two-dimensional electrochemical model correlation mathematical equation based on an electrochemical correlation theory, performing dimensionality reduction processing and calculation solution on a complicated partial differential equation by a finite analysis method and a numerical calculation method, allowing an open circuit potential of an electrode to be equivalent to open circuit voltage of a battery, establishing a capacity-surface SOC-EOCV three-dimensional response surface, extracting and establishing a degradation path graph of a battery performance degradation characteristic parameter by an intelligent optimization algorithm based on battery ageing test data, and finally realizing estimation of the SOH of the power battery based on the degradation path graph and realizing estimation of the SOC of the power battery based on concentration distribution and change rules of lithium ions in the battery.

The invention discloses an evaluation method for unconventional reservoir volume transformation multi-pore media productivity contribution. The evaluation method comprises the following steps that firstly, based on the principle of effective stress and flow characteristics of a transformation zone, and a fluid-solid coupling mathematical model of interaction between a geotechnical deformation field (stress field) and a fluid flow field (seepage field) of the unconventional reservoirs is established; then a perfectly coupled method solution of the seepage field and the stress field is realizedby solving a fluid-solid perfectly coupled system of partial differential equations in a general formula mode; and finally, fluid-solid coupling interactions under different combinations of pore mediaare simulated, and the contribution ratio of three systems of base materials, natural cracks and grid cracks to the cumulative production of a volume transformation well is obtained. A set of evaluation method for unconventional reservoir volume transformation multi-pore media productivity contribution is established eventually. The evaluation method for unconventional reservoir volume transforming multi-pore media productivity contribution has the advantages that the model factor consideration is comprehensive, the evaluation method is simple and results are quantifiable, an oil and gas field can be guided timely to be subjected to development measure adjustment and comprehensive management, and a theoretical basis and technical support are provided to the unconventional reservoir to realize economic recovery.

The invention provides an image denoising method, which comprises the following steps: designing a functional E (u); obtaining a corresponding Euler equation according to the functional E (u); deducing and solving a discrete mathematical model according to the Euler equation, wherein the discrete mathematical model is used for smoothening an image and strengthening detained information; inputting an image u0; carrying out iterative denoising for the input image u0 through the discrete mathematical model, thereby obtaining a denoised image u (i, j); removing spots on the denoised image u (i, j); and outputting an image which spots are removed. The image denoising method provided by the invention overcomes the 'block effect' introduced in the denoising method based on the second-order partial differential equation, and not only denoise the image, but also increases the contrast, thereby maintaining the detailed information of the texture and making the visual effect of the image more vivid and natural.

The invention discloses a method for simulating energy flow based on a transient model of a power-gas interconnection comprehensive energy system. The method comprises the following steps of 1) by considering dynamic characteristics of a slow process of a natural gas pipe network, building a transient model of the natural gas pipe network; 2) by adopting an implicit finite difference method, dividing a time-space partial differential equation for describing dynamic characteristics of gas flow of a natural gas pipeline into algebraic equation expressions; 3) coupling a power network and the natural gas pipe network through a gas turbine and a power-to-gas technology, and building the transient model of the system; 4) solving multi-time-period transient energy flow of the power-gas interconnection comprehensive energy system; and 5) performing performance testing in the comprehensive energy system. According to the method provided by the invention, the calculation precision is effectively improved and a real-time running state of a natural gas system can be described more accurately.

The invention discloses an image de-nosing method based on a partial differential equation filter, mainly solving the problems that the traditional de-nosing method has weaker de-nosing effect and performance. The method comprises the following steps of: (1) inputting a noising image u and calculating a partial derivative of the image u; (2) calculating a gradient modulus absolute Delta of the noising image u; (3) establishing a partial differential equation according to the gradient Delta and the gradient modulus absolute Delta ; (4) calculating a diffusion coefficient and Phi in the partial differential equation; (5) solving the partial differential equation to obtain a filter image by utilizing the coefficient and Phi; (6) calculating the PSNR (Peak Signal to Noise Ratio) of the filter image; and (7) repeating from the step 1 to the step 6. When the PSNR value of the filter image output at some iteration is less than that of the filter image iteratively output at the last time, the iteration is stopped, and the filter image at the last iteration is output. The invention can carry out filtering by utilizing the detailed structures of the image, has simple calculation and fast operation speed, can keep image texture details better at the same time of smoothening noise and can be used for the de-noising treatment of natural images.

The invention discloses an RVM (relevant vector machine) method for RMW (radius of maximum wind) and typhoon eye dimension modeling, in order to establish a model of eye typhoon RMW and typhoon eye dimension based on the RVM. Hereto, according to the invention, the method comprises the following steps of: estimating the RMW through calculating the distance between the coldest temperature point at the top of the cloud and the warmest point within an eye wall on a typhoon cloud picture; dividing the typhoon eye based on patial differential equation, and measuring the dimension of the typhoon eye by the perimeter of the eye wall; and finally establishing the model of the RMW and the typhoon eye dimension based on the RVM, and comparing with the modeling methods of SVM (support vector machine), linear regression, radial basis function neural network and the like. Because the technical scheme provided by the invention is adopted, a good modeling result can be obtained; and compared with other modeling methods, the RVM-based modeling effect has much smaller errors, so that the inner core structure of a wind field at the low layer of typhoon can be depicted favorably.

The present invention is level set system for implementing interactive editing operators for surfaces. Level set models are deformable implicit surfaces where the deformation of the surface (editing operation) is controlled by a speed function in the level set partial differential equation. The level set system overcomes the self-interaction problems associated with mesh models. One embodiment takes scan converts input models such as polygon mesh, NURBS, CSGS models into level set models. An interface is provided by which models can be edited with editing operators such as blending, smoothing, embossing, etc. One embodiment utilizes several methods to optimize computations related to the editing operators. For example, shortest distance calculations, bounding boxes, numerical integration, and the sparse-field methods are disclosed for the implementation of the level set deformation operator embodiments including blending, smoothing sharpening, and embossing. The resulting level sets model can be volume rendered or extracted to a polygon mesh.

The invention relates to a cooling device of heat pipe fins for a power battery system and a mode selecting method. The cooling device of the heat pipe fins for the power battery system comprises a battery box, wherein a plurality of battery module groups are arranged in the battery box in parallel; each battery module group is provided with a heat pipe group in a matched manner; and two ends of each heat pipe group penetrate through the battery box and are connected with cooling fins. The mode selecting method comprises the following steps: establishing equivalent heat resistance models of the heat pipe groups and the cooling fins; establishing a concentrated parameterized ID heat transfer modules for a main heat transfer path after the equivalent heat resistance models are established; establishing a partial differential equation of a heat transfer process of each element; and after determining a convective heat transfer coefficient (h) required for the system, selecting a cooling scheme. The cooling device of the heat pipe fins for the power battery system has the advantages of high cooling efficiency, low complexity of the system and high safety; meanwhile, the expandability is high, the cooling mode can be randomly adjusted according to actual demands of products, and the degree of standardization is high; and IP67 design of the battery box is realized easily, space and cost are saved, and safety of the power battery system is improved.

The invention has opened a free curved surface reflection design procedures and use of one small projection installment lighting system. Free curved surface reflection of light implement design procedures is adopted law of refection , illuminance formula and energy conservation , according to the luminescence characteristic of lamp-house and needed target the balancing illumination, infers a group of partial differential equations, used differences law to find the solution, whose numerical value solution is to be a free curved surface reflection of light implement shape data , the specific target uniform rectangular lighting formed by the free curved surface reflection's refection to the photosource, can be applied to small LED light source for projection Lighting System.Its main merits are: (1) calculation time is short, only a few minutes that will be required for a free curved surface reflection; (2) the utilization of light energy is high; (3) the degree of illumination uniformity is good; (4) applying in the small projection installment of lighting system, will enable the system structure to be more compact.

The invention belongs to the technical field related to structure topological optimization design, and discloses an efficient structure frequency response topological optimization method. The method comprises the following steps that: (1) decoupling two coupling variables including time and space in a standard level set function in a dynamic model of which the structure is to be optimized, and meanwhile, expressing the level set function related to time as a matrix product form; (2) converting a partial differential equation of the time-related level set function into an ordinary differential equation so as to obtain a new linear system, and solving to obtain the time-related level set function; (3) carrying out finite element analysis on a macrostructure so as to calculate a target function and a constraint function of a structure optimization problem; and (4) calculating the sensitivity, which relates to a design variable of the target function and the constraint function obtained in the (3), and judging whether the target function is convergent or not after the design variable is updated. By use of the method, a discrete wavelet transform technology is adopted to carry out recompression on an interpolation matrix, efficiency is improved, and cost is lowered.

The invention discloses a progressive additional lens and a preparation method thereof. According to the prior art, on the basis of acquiring initial rise data of an additional lens surface shape, an optimization method for acquiring small-area local correction surface rise by solving a partial differential equation introducing an optimization function is established. The optimization function is that an optimization factor is added into a lens surface shape average curvature distribution function, the lens surface shape rise is finally obtained by regulating the optimization factor and performing multiple iteration, and the lens is processed, so that the width of an area with the astigmatism less than or equal to 0.25 dioptry in a middle transition area corresponding to the provided lens is increased by more than or equal to 1mm, and the optical property in an effective visual area is not changed basically; therefore, the initial design parameters and the optical property of the lens are kept not changed, the dioptry and the astigmatism distribution of the lens better meet the requirements of wearers.

The invention provides a method for solving solution of elastic foundation beams and for back analysis of value m, belonging to the technical field of geotechnical engineering. The method comprises the following steps of: 1, firstly, converting a fourth order partial differential equation of the elastic foundation beam into a low order partial differential equation set, and setting iteration times and admissible errors; 1, taking a minimum error function of a displacement value sol.y obtained in the step one and an actually-measured displacement value as an objective function, wherein the minimum error function is the sum of squares of difference values; 3, optimizing the objective function in the second step by the application of MATLAB nonlinear optimization algorithm fmincon functions, when reaching the iteration times or the admissible errors set in the first step, stopping iteration, and in this case, the objective function reaching the minimum value; and 4, the parameters corresponding to the minimum value of the objective function being the optimum solution of horizontal resistance factor value m of the to-be-determined soil layer foundation soil. The method provided by the invention is simple in analysis process and easy for programming.

The invention discloses a reverse time migration method of three-dimensional VSP data. The reverse time migration method of the three-dimensional VSP data carries out three-dimensional VSP data reverse time migration based on a three-dimensional acoustic wave equation, can achieve accurate imaging for a complex structure around a well by making full use of the rich wave field information in the VSP data and the imaging capacity of the reverse time migration method on a complex wave field, and provides favorable guidance for complex reservoir exploration. The reverse time migration method of the three-dimensional VSP data takes the wave field information (multiple waves, diffracted waves and the like) accentually existing underground into full account, and does not simplify the wave equation. The method carries out central difference solution on a partial differential equation by using an optimized finite difference coefficient, and is higher in accuracy and more stable in calculation compared with a traditional method. The method is applied to three-dimensional VSP seismic data processing and has great significance for small fracture image beside the well, reservoir forecast, micro-structure implementation and exploration and development of subtle reservoirs.

The invention discloses a heat conduction modeling and calculating method for a natural circulation vapor generator. On the basis of a cylinder wall no-internal-heat-source one-dimensional heat conduction differential equation, distribution of the temperature in a heat transfer pipe in the natural circulation vapor generator and distribution of the temperature in dirt are expressed as a function of the primary side wall temperature and a function of the secondary side wall temperature of the heat transfer pipe, and a function of the outer surface temperature of the dirt, it is supposed that the heat transfer pipe and the dirt are in a quasi stable state in the dynamic process, and the problem of solving a partial differential equation is converted into the problem of solving an ordinary differential equation; in addition, when heat conduction and fluid thermotechnical hydraulic power are coupled, a loose coupling calculation method is adopted, on the basis of ensuring the model precision, the workloads of simulating calculation are greatly reduced, heat conduction of the natural circulation vapor generator is calculated fast, and the method is beneficial for achieving high-precision real-time simulating calculation of the natural circulation vapor generator and a nuclear power unit device, and has the great significance in guiding a nuclear power plant unit to operate safely and reliably.

The invention belongs to the technical field of electric systems. In order to solve the problem of low stability analysis computing efficiency of the original time delay electric system, effectively reduce the dimensionality of a time delay differential equation and achieve higher computing efficiency, the invention adopts a technical scheme that a Lyapunov stability analysis method of a time delay electric system comprises the following steps of establishing a constraint time delay differential equation (CTODE) model of the electric system, rearranging and reorganizing system states in a manner that the states (z1 to z) not considering time delay influence are at the front and the states (z2 to z) considering the time delay influence are at the back, obtaining a CTODE model corresponding to the original time delay system, and basing on a new stability criterion of the CTODE model. The method is mainly applied to the electric system.