12 results about "Curvilinear coordinates" patented technology

The invention relates to the technical field of magnetic suspension conveying lines, in particular to a variable curvature trajectory prediction control method and system for a magnetic suspension conveying line and a storage medium. The method comprises the steps that a variable-curvature trajectory prediction model of the magnetic suspension conveying line is established, and the variable-curvature trajectory prediction model describes the dynamic behavior of a conveying carrier on a variable-curvature path through a kinematics equation and geometric constraints and is used for predicting trajectory deviation in real time. According to the invention, by constructing a variable curvature trajectory prediction model and a multi-target rolling optimization control system, the problems of trajectory tracking and suspension stabilization of a magnetic suspension carrier under a complex path are systematically solved. The method has the advantages that a time domain motion equation is mapped to a space domain path coordinate system based on a curve coordinate system of arc length parameterization and a prediction model constructed by a French-Serret formula, the influence of curvature change on lateral displacement dynamics is accurately described, and dynamics mismatch caused by traditional fixed curvature approximation is eliminated from the model level.

The invention discloses a synchronous bidirectional coupling solving method for large deformation of a flexible slender beam under uniformly distributed pressure based on an accurate load stiffness matrix, and relates to the field of computational mechanics. According to the method, a local curve coordinate system and a uniformly distributed pressure vector function are constructed through an absolute node coordinate Euler-Bernoulli beam unit discrete beam structure, a unit external force vector is derived based on a virtual work principle, and a precise load stiffness matrix is obtained through a vector value function differential rule. The load stiffness matrix and the elastic tangent stiffness matrix are synchronously assembled in the Newton-Rafson iteration step, and synchronous bidirectional coupling solution of the load and the configuration is achieved. According to the method, the numerical value loading limit of a traditional method is broken through, error accumulation is avoided, the calculation stability and precision are improved, the large deformation and even post-buckling behavior of the flexible slender beam under the uniformly distributed pressure can be accurately analyzed, and the method is suitable for design optimization of related equipment in the fields of ocean engineering, mechanical engineering and the like.

The application discloses a semi-open type radial flow and mixed flow impeller tip clearance checking design method and device, relates to the technical field of impellers, and comprises the following steps: obtaining basic data and setting parameters of an impeller tip, wherein the basic data comprises tip deformation data, cold-state tip profile data and meridian cover line data; constructing a curve coordinate mapping relationship of cold-state-hot-state tip profile based on the tip deformation data and the cold-state tip profile data, and constructing a mapping relationship of the curve coordinate of the cold-state tip profile and meridian coordinates based on the cold-state tip profile data and the meridian cover line data; calculating the cold-state tip clearance distribution and the hot-state tip clearance distribution of the pressure side and the suction side tip line of a target blade changing with meridian coordinates according to the curve coordinate mapping relationship of the cold-state-hot-state tip profile and the mapping relationship of the curve coordinate of the cold-state tip profile and meridian coordinates; and calculating the cold-state clearance distribution of the target blade based on the cold-state tip clearance distribution, the hot-state tip clearance distribution and the setting parameters.

The invention discloses a double-soft combined composite roof roadway strain determination method and system, and relates to the technical field of roadway surrounding rock stress. Comprising the following steps: determining a mapping relation between a linear strain and a stress component of a to-be-measured composite roof roadway in a three-dimensional coordinate system; mapping the to-be-measured composite roof roadway to the interior of the unit circle from an infinite domain outside the rectangular hole to obtain a conformal mapping function; performing series expansion on the surrounding rock stress analytic function group to obtain surrounding rock circumferential stress components and surrounding rock shear stress components at the center of the roadway; carrying out simultaneous solution to obtain a stress function; inversely mapping the stress function, the surrounding rock circumferential stress component at the center of the roadway and the surrounding rock shear stress component to an orthogonal curve coordinate system to obtain a mapping relation between normal stresses in the z-axis direction; and substituting into the mapping relation between the line strain and the stress component in the three-dimensional coordinate system to obtain a strain determination result. The method disclosed by the invention fundamentally reveals the key influence of mechanical property differences in different directions on the strain distribution of the surrounding rock of the roadway.

The invention discloses a method and equipment for simulating rugged topography to carry out forward modeling, and the method comprises the steps: building a curved coordinate system according to the form of a target rugged topography, and obtaining the number of curved coordinate systems of each calculation node under the curved coordinate system; electromagnetic parameters required by forward modeling simulation are set, and a radar wave fluctuation equation under the curved coordinate system is split to obtain a plurality of split equations which can be independently calculated; according to the number of the curved coordinate systems and the structure of the splitting equation, the deployment positions of the electric field intensity and the magnetic field intensity in the staggered grids are optimized, so that the staggered grids are matched with the spatial characteristics of the curved coordinate systems and the number of the curved coordinate systems; staggered grid calculation is carried out on the splitting equations, calculation results of the splitting equations are recombined and added, the calculation results are stored in grid units according to a staggered rule, and high-precision forward modeling of the rugged topography is achieved. According to the method, the problems of stepped angular points and derived frequency dispersion and scattering generated when the rugged topography is simulated by a conventional regular grid can be effectively avoided, and the wave field simulation precision is greatly improved.

The invention discloses a path planning method and device, a nonvolatile storage medium and electronic equipment. The method comprises the following steps: acquiring first motion state data of a target vehicle in a rectangular coordinate system and second motion state data of an obstacle vehicle of the target vehicle in the rectangular coordinate system; converting the first motion state data into first target motion state data in a curve coordinate system, and converting the second motion state data into second target motion state data in the curve coordinate system; predicting motion state data of the obstacle vehicle at a second moment in the curve coordinate system; determining the static risk field intensity and the dynamic risk field intensity of the obstacle vehicle; and determining a target path corresponding to the target vehicle according to the first target motion state data and the total collision risk. According to the method and the device, the technical problem of inaccurate path planning when the vehicle faces the obstacle vehicle caused by insufficient accuracy of predicting the motion state of the obstacle vehicle and incapability of comprehensively evaluating the collision risk is solved.

The application discloses a synchronous bidirectional coupling solving method for large deformation of a flexible slender beam under uniform pressure based on an accurate load stiffness matrix and relates to the field of computational mechanics. The method discretizes a beam structure through absolute node coordinate Euler-Bernoulli beam elements, constructs a local curvilinear coordinate system and a uniform pressure vector function, derives an external force vector of the element based on a virtual work principle, obtains an accurate load stiffness matrix through a vector-valued function differential rule, synchronously assembles the load stiffness matrix and an elastic tangent stiffness matrix in a Newton-Raphson iteration step, and realizes synchronous bidirectional coupling solving of load and configuration. The method breaks through the numerical loading limit of a traditional method, avoids error accumulation, improves calculation stability and precision, can accurately analyze large deformation and even post-buckling behavior of the flexible slender beam under uniform pressure, and is suitable for design optimization of related equipment in the fields of ocean engineering and mechanical engineering.

The present invention is directed to computer-implemented method for controlling an autonomous or semi-autonomous vehicle. A vehicle model is provided and information describing a roadway (301) is obtained. This information is transformed in a Frenet-Serret frame, which defines a curvilinear coordinate space. Then, in the curvilinear coordinate space, a plurality of line segments (306, 307) are defined (3) along the roadway (301), at locations spaced longitudinally along a reference line defining the Frenet-Serret frame. The line segments have respective lengths that extends, each, perpendicularly to the reference line. Next, based on the defined line segments, a space-time corridor (327, 327″, 326″) is determined (5) to obtain a time-dependent space available for the vehicle. Bounds for the vehicle within said time-dependent space are subsequently obtained (6). The bounds define a set of constraints that delimit a plurality of convex space-time objects along the reference line. Said objects approximate the time-dependent space. Then, based on the obtained set of constraints and the provided vehicle model, the method provides (7) a motion trajectory of the vehicle through the plurality of convex space-time objects. This motion trajectory is optimized using a nonlinear programming solver. Finally, the motion trajectory is transformed (8) from the curvilinear coordinate space to a Euclidean coordinate space, to control the vehicle based on the transformed motion trajectory. The present invention further concerns related systems and computer program products.

This invention discloses a high-strength metal-SiC f This invention relates to a SiC heterogeneous cladding tube structure and its design method. The heterogeneous cladding tube comprises a refractory metal liner and a multi-layered SiC fiber preform with braiding angles ranging from 0° to 45°. The design method includes: A. Establishing a geometric model of the multi-layered heterogeneous cladding tube; B. Meshing the geometric model into a solid mesh; C. Establishing a curvilinear coordinate system; D. Setting boundary conditions for the geometric model; E. Defining the mechanical damage criteria for each component of the geometric model; F. Calculating the stress-strain curves of the multi-layered heterogeneous cladding tube; G. Determining the structural design of the high-strength multi-layered heterogeneous cladding tube. The multi-layered heterogeneous cladding tube designed in this invention exhibits excellent axial and circumferential tensile strength. Furthermore, the use of the finite element method in the structural design reduces the time cycle from material design to application, thereby enabling rapid optimization of accident-tolerant fuel cladding structures.

The application discloses a semi-open type radial flow and mixed flow impeller tip clearance checking design method and device, relates to the technical field of impellers, and comprises the following steps: obtaining basic data and setting parameters of an impeller tip, wherein the basic data comprises tip deformation data, cold-state tip profile data and meridian cover line data; constructing a curve coordinate mapping relationship of cold-state-hot-state tip profile based on the tip deformation data and the cold-state tip profile data, and constructing a mapping relationship of the curve coordinate of the cold-state tip profile and meridian coordinates based on the cold-state tip profile data and the meridian cover line data; calculating the cold-state tip clearance distribution and the hot-state tip clearance distribution of the pressure side and the suction side tip line of a target blade changing with meridian coordinates according to the curve coordinate mapping relationship of the cold-state-hot-state tip profile and the mapping relationship of the curve coordinate of the cold-state tip profile and meridian coordinates; and calculating the cold-state clearance distribution of the target blade based on the cold-state tip clearance distribution, the hot-state tip clearance distribution and the setting parameters.

This invention discloses a method for determining riverbed morphological feature parameters based on digital river topography, comprising the following steps: acquiring remote sensing image data, determining the left and right bank boundary lines of the corresponding time study section, and obtaining a planar scatter set of the bank boundary lines; acquiring a river topographic map and constructing a three-dimensional coordinate set of the bank boundary lines; determining the scatter set of the river center, fitting and generating the river centerline, and extracting the cross-sectional lines perpendicular to the river centerline, establishing an orthogonal curvilinear coordinate system; and determining the planar morphological feature parameters, cross-sectional morphological feature parameters, and deep-water longitudinal profile morphological feature parameters of the river under the orthogonal curvilinear coordinate system. This invention, based on remote sensing image data and river topographic data, solves the problems of previous methods that only allowed extraction by river type and river section, excessively large fixed cross-sectional spacing, unreasonable cross-sectional layout, and the inability to directly calculate riverbed morphological feature parameters, thus overcoming the technical bottleneck of automatically and efficiently extracting riverbed morphological feature parameters from digital river topography.

This invention discloses a method for airfoil parameterization in a fixed disturbance design space, belonging to the field of airfoil optimization technology. The method includes the following steps: mapping the basic airfoil to a Cartesian coordinate system to obtain the upper and lower airfoil curves; obtaining the intermediate guide line, relative upper airfoil curve, and relative lower airfoil curve; dividing the total design space into four design spaces and establishing orthogonal curvilinear coordinate systems for each; obtaining relative airfoil function curves; adding disturbance functions to the relative airfoil function curves to obtain disturbed relative airfoil function curves; transforming the disturbed relative airfoil function curves from their respective orthogonal curvilinear coordinate systems to a Cartesian coordinate system to obtain disturbed airfoil function curves; obtaining the disturbed upper and lower airfoil curves to obtain the disturbed airfoil, thus completing airfoil parameterization.