44 results about "Point boundary" patented technology

The invention relates to an interplanetary transfer orbit design method, in particular to a transfer orbit design method from a periodical orbit which is near dynamic balance points of a three-body system to a small celestial body and belongs to the technical field of aerospace. Firstly, based on the periodical orbit which is near the dynamic balance points of the three-body system where a detector is located, an initial state of the detector x0=[ r0, v0] is assumed. Secondly, a speed increment delta v is exerted along a tangential direction so that the detector sets off from the periodical orbit near the dynamic balance points. Based on a multiple-body model, relations between the detector and a distance df of the detector and the target small celestial body, a flying period tf and the tangential direction speed increment delta v are built up when the detector flies across the target small celestial body is built. Through an optimizing algorithm, an initial value of the transfer orbit is obtained when the fight distance df is minimum. Finally, a secondary-level differential correction method is used based on the initial value to obtain orbit parameters which can meet two point boundary values. The interplanetary transfer orbit design method can achieve rapid design of flight from the periodical orbit which is near the dynamic balance points of the three-body system to the small celestial body, calculation amount is small and efficiency is high.

The invention discloses an optimal orbital transfer method of a low-earth-orbit satellite under a limited thrust by taking J2 perturbation into consideration, relates to the optimal orbital transfer method of the low-earth-orbit satellite, and belongs to the field of aerospace. The optimal orbital transfer method comprises the following steps of: establishing a dynamic equation of a spacecraft by taking the J2 perturbation into consideration; solving a Hamiltonian function H corresponding to an optimal fuel consumption performance index according to the states of the spacecraft at the beginning and the end; solving an optimal control rate and a corresponding covariance equation according to a pontryagin maximum principle; constructing a two-point boundary value problem shooting equation set meeting the optimal fuel consumption according to an optimal control condition of a variational method; solving the two-point boundary value problem shooting equation set according to the states of the spacecraft at the beginning and the end as well as the flight time to obtain the optimal control rate formed by an optimal thrust control direction and an engine switching function; and controlling the orbital transfer of the satellite by using the control rate, so that the real-time performance and the orbital transfer precision in the transfer process of the low-earth-orbit satellite can be increased, and the fuel consumption required for the orbital transfer is reduced. The optimal orbital transfer method disclosed by the invention is suitable for the orbital transfer process of the low-earth-orbit satellite when a limited thrust model is adopted by an engine.

The invention discloses a track planning method of turning curved surface zone having equal scallop-height into a cutter processing, which belongs to the technical field of highly-precise and highly-efficient milling and processing of complicated curved surface parts. The track planning method of turning curved surface zone having equal scallop-height into a cutter processing comprises the steps of conducting zone partitioning on the curved surface based on the geometric features and processing requirement of the curved surface; determining the boundary of adjacent processing zones; conductingthe initial plan of equal scallop-height processing track on different processing zones. Through analyzing the geometric features of boundary, the geodesic radius of curvature and the cutter space along the space direction can be calculated, and the cutter contact point and cutter position point corresponding to any points on the boundary of adjacent processing zones can be resolved. The cutter position points form the cutter point boundary through interpolation and fitting. The invention is advantageous in that planning can be conducted with the cutter position point being the constraint, and it can be guaranteed that the cutter position point falls in the cutter position point boundary and on the boundary; the cutter position point can be adjusted, so that the error brought by planningcan be homogenized; the method is suitable for turning the complicated curved surface into cutter processing, and gear mark can be reduced, and processing quality can be improved.

The invention discloses a covariant initial value determination method for the optimal landing track design and belongs to the field of deep space exploration. The covariant initial value determination method includes building a small body fixing coordinate system and corresponding detector landing kinetic equations; converting the optimal design problem of the small body landing track into the optimal control problem and the corresponding two-point boundary value problem, and defining the problems as the problem 1; approximating the problem 1, and defining the approximated problem 1 as the problem 2; solving the covariant initial values lambda<r2(t0)> and lambda<v2(t0)> of the problem 2, setting the the covariant initial values lambda<r2(t0)> and lambda<v2(t0)> of the problem 2 as iterative initial values of the covariant initial values lambda<r1(t0)> and lambda<v1(t0)> of the problem 1, determining the iterative initial value of the covariant initial value lambda<m1(t0)> of the problem 1 according to the setting of the iterative initial values, namely lambda<r2(t0)> and lambda<v2(t0)>, of the covariant initial values lambda<r1(t0)> and lambda<v1(t0)> of the problem 1, thereby achieving the iterative initial value setting of the covariant initial values for the optima landing track design. The defect that it is difficult to solve the two-point boundary value problem due to improper initial value setting can be avoided by application of the method.

The invention belongs to the technical field of high-precision and high-efficiency milling processing of complex curved surface parts, and relates to a curved-surface partitioned processing trajectoryplanning method based on boundary residual height constraint. The curved-surface partitioned processing trajectory planning method comprises the steps of: defining a residual height at a boundary ofa processing region, analyzing geometric features of the processing region, solving of cutter contact point positions under the boundary residual height constraint, and constructing cutter contact point boundaries; selecting one cutter contact point boundary as an initial processing trajectory according to processing requirements, and calculating a geodesic line of the cutter contact point boundary along a line spacing direction; establishing a functional relationship between the residual height and an arc length between the adjacent cutter contact points, generating cutter contact points recursively along the line spacing direction, calculating an arc length error of the tail end cutter contact point and the cutter contact point boundary, and acquiring adjusted cutter contact points through sensitivity analysis; and connecting the cutter contact points corresponding to the geodesic lines along a feed direction, and completing trajectory planning according to the boundary constraint and step length constraint. The curved-surface partitioned processing trajectory planning method is suitable for partitioned processing of complex curved surfaces, can reduce the gear marks and improvethe processing quality.

The invention discloses a three-dimensional terrain simplification algorithm based on high-precision DEM data, comprising the following steps: 1) quadtree data structure design, 2) calculating the viewpoint-independent error of the irregular triangular network, 3) quadtree node Subdivision, 4) Terrain simplifies error judgment. Compared with the common DEM, this algorithm has a special design for the quadtree data structure. After calculating the viewpoint-independent error of the irregular triangulation, the error value is further subdivided, and further error judgments are made, and the establishment of a large-scale, large-scale real-time, interactive virtual terrain While the environment is simplified, the complexity of the nodes is simplified by calculating the importance measure of each node, thereby improving the efficiency of terrain rendering, and the terrain details of the obtained effect map are detailed and real.

The invention discloses an operational curved surface method for determining asymmetric short-circuit current of a distributed generation access power grid. The method comprises steps of acquiring a three-node simplified network and transfer impedance between different nodes by using network simplification when multiple DGs and conventional generators have access to the power grid; in view of different types of asymmetric short-circuit faults, ignoring the influence of DG zero-sequence current injection, obtaining a short-circuit calculation compound sequence network and positive and negative sequence augmented networks according to a fault point boundary condition, and calculating the additional voltage and additional impedance in the augmented networks; performing Thevenin equivalent on systems except the DG access points in the positive and negative sequence networks, and deriving short-circuit impedance and open-circuit voltage open-circuit voltage computational formulas when DC injection current is zero; establishing a operational curved surface of a DG short-circuit current negative-sequence component, computing impedance, and positive and negative sequence open-circuit voltage in order to obtain a DG short-circuit current negative-sequence component; calculating a DG asymmetric short-circuit current positive-sequence component in combination with a three-phase short-circuit operational curved surface according to a DG access positive-sequence augmented network access point equivalent open-circuit voltage computing method.

The invention discloses an urban road network time varying K shortest path search algorithm capable of considering turn delays. The algorithm comprises the following steps that: on the basis of obtaining the intersection turn delays of continuous equal time intervals and a road section stroke time data sequence, combining with an extended network method to obtain time varying impedance between intersection boundary lines in a network; adopting an A* algorithm to search a shortest path and stroke time from an appointed starting point boundary line to an end point boundary line; and furthermore, circularly adopting a connecting line deletion method and the A* algorithm to delete the shortest path under parts of connecting line conditions until search for the appointed K time varying shortest path is finished. By use of the time varying K shortest path search algorithm provided by the invention, the influence on path search by the time variation and the intersection delay of the urban road network impendence is simultaneously considered, a globally optimal result can be obtained at a high calculation speed, and the algorithm exhibits good maneuverability.

A drive assist system includes: an acceleration change pattern setting portion that sets an acceleration change pattern of a vehicle that is a pattern of change in acceleration of the vehicle that occurs while the vehicle travels on a road; and a drive plan generating portion that generates a drive plan for the vehicle based on the acceleration change pattern set by the acceleration change pattern setting portion. The drive assist system generates a drive plan satisfying three conditions, namely, a kinetic model of the vehicle, a passing point of each corner, and an acceleration change pattern, using a solution to two-point boundary-value problems.

The invention discloses a calculating method for measuring thermal performance of a filler of a lower cooling tower based on a two-point boundary value. The method comprises the following steps of describing heat and mass transfer in the filler through four ordinary differential equations; collecting field operation parameters and environment parameters of the cooling tower, confirming air temperature Ta and humidity ratio X of the bottom part (z is equal to 0) of the filler, and water temperature Tw and mass flow rate mw boundary values of the top part (z is equal to H) of the filler; assuming and iteration adjusting unknown boundary conditions of the bottom part (z is equal to 0) of the filler, so that the top part (z is equal to H) of the filler meets known boundary conditions; building a cooling tower filler thermal performance calculation model based on a filler thermal performance linear model; substituting into the above for calculation to obtain the conditions of the top part (z is equal to H) of the filler, and calculating the cooling tower thermal performance. According to the method, model building is carried out based on real-time measurement values, so that real-time on-line evaluation of the cooling tower thermal performance can be realized favorably, the calculation model is simplified under the measurement based on the two-point boundary value, and compared with the existing calculation method, under the premise of ensuring the calculation accuracy, the calculation time is greatly shortened.

The invention discloses a touch screen-based mobile terminal unlocking method, a touch screen-based mobile terminal unlocking system and a mobile terminal. The method comprises the steps: setting a starting point boundary and an end point boundary of an unlocking sliding track for success unlocking on the mobile terminal in advance; under an unlocking interface, obtaining the sliding track on a touch screen of a user; judging whether a starting point coordinate boundary and an end point coordinate boundary of the track are consistent with the preset starting point boundary and the preset end point boundary of the unlocking sliding track, if so, successful unlocking is realized, otherwise, unsuccessful unlocking is prompted. By applying the touch screen-based mobile terminal unlocking method, the touch screen-based mobile terminal unlocking system and the mobile terminal, a new function is added to the mobile terminal, multipath sliding unlocking is realized, path unlocking of the mobile terminal is more flexible, options of sliding unlocking are enriched, and convenience is brought to users.

The invention, which relates to the technical field of power system monitoring, discloses a method for calculating a tree cutting area in a tree obstacle hidden danger area of a power transmission line. The method includes the following steps: S1, scanning the power transmission line by using a laser radar device to obtain laser point cloud data of the power transmission line; S2, preprocessing the laser point cloud data obtained in the step S1, realizing fine classification of the data through manual interaction, and extracting tree obstacle hidden danger point data; S3, extracting a tree barrier hidden danger point boundary to obtain a minimum polygon of a hidden danger area; S4, dividing the minimum polygon in the step S3 into a plurality of triangles; and S5, solving the sum of the triangular areas in the step S4 as the area of the tree barrier hidden danger area.

The embodiment of the invention provides a small celestial body landing trajectory optimizing method considering a gravitation attitude and orbit coupling effect. The small celestial body landing trajectory optimizing method considering the gravitation attitude and orbit coupling effect comprises the steps of obtaining coordinate system definition, a small celestial body gravitational field calculation method and a detector discrete mass model; obtaining a detector six-degree-of-freedom kinetic model according to the coordinate system definition, the small celestial body gravitational field calculation method and the detector discrete mass model; using an indirect method to obtain a fuel optimal two-point-boundary-value problem model according to the detector six-degree-of-freedom kineticmodel; and using a two-stage homotopy method to calculate the fuel optimal two-point-boundary-value problem model to obtain a small celestial body landing fuel optimal trajectory considering the gravitation attitude and orbit coupling effect according to the fuel optimal two-point-boundary-value problem model. According to the technical scheme provided by the embodiment of the invention, effectivecalculation of the small celestial body landing trajectory optimizing problem can be realized to obtain a six-degree-of-freedom fuel optimal trajectory; and therefore, additional fuel consumption generated during rigid body detector trajectory tracking under the gravitation attitude and orbit coupling effect is avoided, and the fuel optimality of a landing task is guaranteed.

The invention relates to a large-range multi-target cannonball blasting point sound source locating method. A central station and multiple substations are included, the central station is electrically connected with the substations for data communication, and each substation is provided with a microphone sound source sensor; and the central station is provided with a computer for starting sound wave collection of all the substations. When a blasting point event occurs, the microphone sound source sensor which is close to a cannonball falling region is automatically selected through a program, and then a blasting point sound wave locating method is invoked for giving a computation result. The large-range multi-target cannonball blasting point sound source locating method has the advantages that according to the blasting point locating method, blasting point signals which are collected by the multiple sound sensors distributed on the falling point boundary are selected, and the large-range cannonball blasting point locating requirement is met. The blasting point locating method is not only suitable for locating a blasting cannonball, but also suitable for locating a non-blasting cannonball. The blasting point locating method is not only suitable for locating a single cannonball, but also suitable for locating rapid-fire cannonballs; and in addition, calculation is rapid to achieve, the automation degree is high, and a very satisfactory effect is obtained in actual shooting range experiments.

The invention discloses an improved thermal power plant boiler temperature field reconstruction temperature measuring algorithm. The improved thermal power plant boiler temperature field reconstruction temperature measuring algorithm comprises the following steps that firstly, a sound wave propagation path ordinary differential equation mathematical model of sound waves in a non-uniform temperature field in a hearth is derived according to the target requirement and the propagation characteristic of the sound waves in the non-uniform temperature field, by means of the functional extremum problem and geodesic problem and on the basis of the Fermat principle; secondly, an ordinary differential equation is solved through a shooting method, the nonlinearity two-point boundary value problem of the sound wave propagation path mathematical model is converted into an ordinary initial value problem, approaching is achieved by setting different initial values in an iteration mode, and the numerical solution of the sound wave propagation path is worked out through the numerical value; thirdly, on the basis of sound wave propagation path correction, the acoustic CT algorithm is called, the sound wave propagation path in an original algorithm is improved according to a linear processing method, and the temperature field reconstruction and the like are carried out by introducing the actual sound wave propagation path bent through the effect of the non-uniform temperature field.

The invention belongs to the field of non-linear differential game control, and provides a random non-linear differential game control method based on statistic linearization. The random non-linear differential game control method based on the statistic linearization comprises the following steps of: carrying out similar linearization on a system non-linear function by using a statistic linearization technology according to system state random probabilistic nature, and deriving with a random dynamic programming method to obtain analysis controller containing a statistic linearization coefficient; and meanwhile, carrying out statistic linearization on a non-linear saturation function by considering a condition that a control mount in actual engineering is limited by saturation, so as to obtain an analysis controller in a saturation limited condition. The controller consists of two parts of a system state feedback part and a statistic linear coefficient feedback part. With the adoption of the method, the two-point boundary problem caused by solving a non-linear (partial) differential equation (set) can be effectively avoided; and the random non-linear differential game control problems can be more conveniently solved on the premise that certain solving accuracy is ensured, so that multiple functions which cannot carry out the linearization by using Taylor series expansion have possibility of carrying out the linearization. The method is particularly suitable for functions, such as phase step and saturation control and digital conversion switch which are most used on aircraft, and has strong popularization and application values.

The invention discloses a fertilizer distribution control system and method, which solves the problem that fertilizer distribution equipment is difficult to guarantee uniformity in the prior art, andhas the effect of being capable of improving the fertilizer distribution efficiency, reducing the labor intensity and reducing the waste of fertilizer. The system adopts the technical scheme that thesystem comprises a central control unit, a human-computer interaction module and a visual identification module, wherein the input terminal of the central control unit is connected with a load sensor,a rotate speed sensor and the visual identification module; the output terminal of the central control unit is connected with an electronic throttle valve and an electromagnetic valve; preset fertilizer distribution amount is input to the human-computer interaction module; the load sensor obtains fertilizer change data and inputs the data to the central control unit; the rotate speed sensor collects wheel rotate speed signals and inputs the signals to the central control unit; the central control unit computes practical fertilizer distribution amount and fertilizer distribution vehicle practical traveling speed; the visual identification module recognizes a fertilizer dropping point boundary; the central control unit works out dispersing distance.

There are provided respective systems and methods for recording and playing back media content. The system for recording media content includes a segmenter (303) for splitting transport stream data and index data corresponding to the media content into discrete files at periodic intervals on access point boundaries. Each of the discrete files includes a respective transport segment and a respective index segment. The system also includes a segment storage device (304) for storing the discrete files.

The invention provides a compressor blade suction surface primitive curve modeling method based on a second order ordinary differential equation, and the method comprises the steps of pre-treating compressor blade primitive curve data; and selecting a second order ordinary coefficient linear non-homogeneous ordinary differential system for fitting to obtain an expression of a primitive curve. According to the boundary condition requirement, a second-order curve problem coinciding with the first and last points of the given data is transformed into a two-point boundary value problem; an Implicit Euler method is selected for solving an intermediate point of a primitive curve. In this way, the primitive curve is reconstructed. According to the invention, the problem that a first order system can't guarantee interpolation conditions at the first and last points at the same time is solved; a larger optimization operation space is obtained; and sensitive degree to a parameter matrix is reduced. Interpolation in the first and last points of data scatter is accurate, which has a great advantage in connecting data scatter that is fitted in sheets or segments; and the shape of a compressor blade can be restored in high precision.