1835 results about "Differential equation" patented technology

A virtual reality display system that generates display images in two phases: the first phase renders images based on a predicted pose at the time the display will be updated; the second phase re-predicts the pose using recent sensor data, and corrects the images based on changes since the initial prediction. The second phase may be delayed so that it occurs just in time for a display update cycle, to ensure that sensor data is as accurate as possible for the revised pose prediction. Pose prediction may extrapolate sensor data by integrating differential equations of motion. It may incorporate biomechanical models of the user, which may be learned by prompting the user to perform specific movements. Pose prediction may take into account a user's tendency to look towards regions of interest. Multiple parallel pose predictions may be made to reflect uncertainty in the user's movement.

Disclosed are apparatus and methods for determining process or structure parameters for semiconductor structures. A plurality of optical signals is acquired from one or more targets located in a plurality of fields on a semiconductor wafer. The fields are associated with different process parameters for fabricating the one or more targets, and the acquired optical signals contain information regarding a parameter of interest (POI) for a top structure and information regarding one or more underlayer parameters for one or more underlayers formed below such top structure. A feature extraction model is generated to extract a plurality of feature signals from such acquired optical signals so that the feature signals contain information for the POI and exclude information for the underlayer parameters. A POI value for each top structure of each field is determined based on the feature signals extracted by the feature extraction model.

A method and apparatus for dynamically separating and recovering original signal sources by processing a set of mixed received mixtures and convolution of said signals utilizing differential equations and a computer. The system of the invention enables the blind separation and recovery of an unknown number of signals mixed together in dynamically changing interference environments with very minimal assumption on the original signals. The system of this invention has practical applications to nonmultiplexed media sharing, adaptive interferer rejection, acoustic sensors, acoustic diagnostics, medical diagnostics and instrumentation, speech, voice, language recognition and processing, wired and wireless modulated communication signal receivers, and cellular communications.

The invention discloses a human body attitude calculation method based on quaternion and Kalman filtering. The method comprises determining a vector coordinate system and a navigation coordinate system, determining an attitude matrix, respectively acquiring accelerated speed, angular velocity and magnetic induction intensity signals through an accelerometer, a gyroscope and a magnetometer, carrying out initial alignment on a human body attitude detection system, calculating initial attitude angles such as a pitching angle, a rolling angle and a heading angle, transforming the initial attitude angles into initial quaternion, carrying out system modeling according to a quaternion differential equation, inputting the initial quaternion as a measured value, carrying out data fusion on the attitude data through a Kalman filtering algorithm, outputting an estimated value which is updated quaternion, carrying out normalization processing on the updated quaternion to obtain final posture information, updating the attitude matrix and acquiring updated attitude angles. The human body attitude estimation method effectively improves the accuracy of human posture detection, has a fast response speed, has good stability and instantaneity and has a broad application prospect.

The instant invention is a method for numerically propagating waves or solving wave equations on a digital computer. This invention can be used to compute highly accurate solutions to the wave equation, in fact in some cases it computes the analytical solution, something previously considered impossible. The instant method can also propagate waves that are not described by differential equations, such as anisotropic scalar waves. The invention has the advantages that it is computationally efficient, accurate, and flexible. Of importance is the ability to propagate waves that simulate the P-wave arrivals in both isotropic and anisotropic media with a scalar as opposed to a vector equation.

An e-book allowing note and corrigendum sharing as well as differential update is produced using vector graphics satisfying XML syntax, and a script program is embedded in or linked to the e-book. The script program allows a user to add various kinds of note markups to the e-book, including fluorescent marker, text annotation, handwriting note, bookmark, digital blackboard record, post-it note, highlight, voice, memo, tracking information, etc. The e-book also allows an e-book editor to correct any error in the e-book. The note markups and corrigenda may be uploaded via network, and be shared among other users by way of differential update.

The invention provides a vehicle autonomous parking path programming method used for multiple parking scenes. The method is used for automatically parking a vehicle in a parking space through an autonomous parking system when the autonomous parking system detects the available parking space. The method includes the steps that target parking space information is detected, and a parking scene is determined; the initial state and target state of the to-be-parked vehicle are determined; a vehicle kinematics differential equation is established; state variables and control variables of the vehicle are segmented, equidistance sampling is performed on each segment according to certain time step, and to-be-optimized variables are obtained; an equality constraint, boundary constraints and inequality constraints of the to-be-optimized variables are formed; motion range constraints of the to-be-parked vehicle are formed according to the motion range limit in the parking process of the vehicle; an optimization objective is determined, and an objective function is established; and by means of a nonlinear programming solver, an optimal solution of a parking path is obtained. The vehicle autonomous parking path programming method is suitable for the multiple parking scenes, the design is reasonable, abundant information can be provided so as to control autonomous parking of the vehicle, and the security coefficient is high.

The invention relates to receivers and methods for receiving multi-carrier differentially modulated signals utilizing iterative decision-directed differential detection. The receiver includes a decision feedback loop including a channel estimator for estimating inter-symbol channel variations, and a differential equalizer for correcting channel-induced errors in a differentially detected signal based on the estimated inter-symbol channel variations.

The invention relates to a moving target detecting method based on differential fusion and image edge information. The method comprises the following steps of: extracting a video image for preprocessing, and extracting the edge of the image to acquire continuous edge images; performing inter-frame differential operation on the continuous edge images respectively in a unit 8 data format, and performing background differential operation on the image in an intermediate frame; and fusing the detecting results of two differences to primarily extract a moving pedestrian target. In a background difference, a background automatic extracting method is improved, and a continuous-edge-image-based background image extracting and updating method is provided. A moving target area in the image is extracted by using an adaptive-background-model-based dynamic threshold value, and morphologic filtering and connectivity detection are performed, so that the foreground target of a moving pedestrian is acquired. Under the complex condition of sudden light variation, a moving target can be accurately and reliably detected, and the method is superior to the three traditional methods in the two aspects ofan identification rate and an error detection rate.

A method for segmenting intravascular images includes acquiring a series of digitized images acquired from inside a vessel, each said image comprising a plurality of intensities corresponding to a 2-dimensional grid of pixels, providing a precomputed set of shapes for modeling contours of vessel wall boundaries, wherein a contour can be expressed as a sum of a mean shape and a inner product of shape modes and shape weights, initializing a boundary contour for one of said set of images, initializing said shape weights by projecting a contour into said shape modes, updating said shape weights from differential equations of said shape weights, and computing a contour by summing said mean shape and said inner product of shape modes and updated shape weights.

A signal detection and classification technique that provides robust decision criteria for a wide range of parameters and signals strongly in the presence of noise and interfering signals. The techniques uses dynamical filters and classifiers optimized for a particular category of signals of interest. The dynamical filters and classifiers can be implemented using models based on delayed differential equations.

The invention relates to a computer application in the field of control, monitoring, modification and / or optimization of processes which comprise real process sequences of discrete events, so-called "discrete event dynamic systems", which cannot usually be described by systems of (differential) equations. Such processes occur for example in technical developments as well as in other business activities in the industrial or tertiary sector. Such a real process is reflected in a process model which is connected to the real process via at least one interface. If the interface(s) is / are bi-directional, real process data can be transmitted into the model directly, i.e. without data conversion, and thus the real process can be monitored; in the model, simulations can be carried out with changed process data; and finally if the result of the simulation is successful, process modifications can be transferred directly to the real process.

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.

A difference region extracting section 122 extracts differential regions based on screen data of a previous screen stored in transmission screen data storage section 124 and a current screen stored in a screen data storage section 121. A priority determining section 123 calculates change data density indicating a degree of a change of pixel values for every differential region. For example, when a user operates an icon on the screen, the change data density of the differential region corresponding to the icon becomes larger than the change data density of the differential region corresponding to the background portion of a video image. An encoding section 125 writes screen code data of each differential region in a transmission buffer 141 in descending order of the change data density.

Method for estimating the Hessian of the objective function, times a vector, in order to compute an update in an iterative optimization solution to a partial differential equation such as the wave equation, used for example in full wave field inversion of seismic data. The Hessian times vector operation is approximated as one forward wave propagation (24) and one gradient computation (25) in a modified subsurface model (23). The modified subsurface model may be a linear combination of the current subsurface model (20) and the vector (21) to be multiplied by the Hessian matrix. The forward-modeled data from the modified model are treated as a field measurement in the data residual of the objective function for the gradient computation in the modified model. In model parameter estimation by iterative inversion of geophysical data, the vector in the first iteration may be the gradient of the objective function.

A general, computational-mathematical modeling method for the solution of large, boundary-coupled transport problems involving the flow of mass, momentum, energy or subatomic particles is disclosed. The method employs a modeling processor that extracts a matrix operator equation (or set of equations) from a numerical transport code (NTC). The outputs of software codes, available for modeling physical problems governed by conservation laws in the form of differential equations, can be processed into closed-form operator equations with the method. Included is a numerical transport code functionalization (NTCF) model which can be determined numerically, based on a system of solutions of an NTC, evaluating outputs for a given set of inputs. The NTCF model is a linear or nonlinear, multi-variable operator equation or set of such equations. The NTCF model defines relationships between general, time-variable inputs and outputs, some known and some unknown, considered as boundary values. The user of an NTCF model can directly work with the processed model output, instead of running the original numerical code in general applications of a boundary-value problem. The numerical transport code functionalization model can be employed as a surrogate for representing the numerical transport code to provide a solution to the transport problem. The invention enables modeling efficiency and availability to be increased, while computational complexity and cost decreased. Computational times for complex modeling problems can, in some cases, be dramatially reduced, for example by several orders of magnitude.

A differential device is provided with a case being capable of rotation around a rotation axis; a differential gear set housed in and drivingly coupled to the case, which includes first and second output gears and is configured to differentially transmit the rotation of the case to the first and second output gears; a clutch configured to controllably limit and free a differential motion between the first and second output gears, which is housed in the case; an actuator configured to actuate the clutch; and a notifying member configured to notify whether the differential motion is limited or freed to an exterior of the case.

The invention provides a design optimization method and an optimization device of a power assembly mounting system. The design optimization method comprises the steps of establishing a differential equation of a space six-freedom degree vibration model of the power assembly mounting system; analyzing to obtain an inherent frequency, an inherent vibration mode and vibration energy coupling among six freedom degrees according to inherent characteristics of the differential equation for the power assembly mounting system; establishing a multiple target optimization function of the power assembly mounting system according to each order inherent frequency, inherent vibration mode and vibration energy coupling; and carrying out optimization design with a particle swarm optimization algorithm. A dynamical model and the optimization function of the power assembly mounting system are established, the multiple target optimization function with reasonable distribution of mounting modal frequency and decoupling degree of energy as targets is determined, and a parallel optimization multiple target algorithm is subsequently adopted to obtain a multiple target optimization scheme set of the power assembly mounting system so that the designed power assembly mounting system can best meet the performance requirements of energy decoupling and modal distribution.

Illumination lenses (1806, 1902, 2002, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 3006, 3100) having surfaces shaped according to given differential equations in order to distribute light in a highly controlled manner with minimum reflection losses are provided. Both primary lenses and secondary lenses are provided. The secondary lenses include outer surfaces that are defined as loci of constant optical distance from an origin at which a light source is located. Versions are provided of both the primary and secondary lenses having Total Internal Reflection (TIR) wings. These are useful in the case that narrower distributions of light are required. A method of refining the shape of the lenses to obtain more obtain lenses that produce better fidelity ideal light distributions is also provided.

Abstract of Disclosure A calibration factor for a sensor including a material-containing conduit and a plurality of motion transducers operative to generate motion signals representing motion of the conduit is determined from a normal modal dynamic characterization of motion of the conduit. The calibration factor may be generated by generating a solution to a modal differential equation of motion in a modal domain including a plurality of normal modes of motion of the conduit, and by generating the calibration factor from this solution. The normal modal dynamic characterization may characterize motion of the conduit as a function of a modal Coriolis term that describes coupling among a plurality of normal modes of the conduit responsive to mass flow in the conduit. The modal Coriolis term may be determined from a mode shape function that describes modal motion of the conduit as a function of location on the conduit. The invention may be embodied as methods, apparatus and computer program products.

An analytical apparatus for optimally combining measurements from N individual rate sensing devices or gyros into a single rate estimate significantly improves performance over that of any individual component device. Kalman filtering is used to combine rate sensed devices optimally in the sense of minimizing the variance of the rate error. The Riccati differential equation (RDE) associated with combining a collection of rate sensed devices is completely and exactly solved to derive to the matrix RDE. This analytic solution serves as the key for understanding all of the theoretical properties of the optimal filter, and provides a complete characterization of the final virtual rate sensed performance. In addition, the analytic RDE solution allows many practical problems to be solved that have proved essential for developing successful filter implementations. A discrete-time minimum variance filter implementation combines sensor measurements optimally.

In the invention, a rover receiver first utilizes data from a base Receiver, a DGNSS reference network, or other differential source to compute a differentially corrected location. Then, using this location and data observed only at the rover, the rover computes an internal set of differential corrections that are stored in computer memory, updated as necessary, and applied in future times to correct observations taken by the rover. The possibly mobile rover receiver, therefore, corrects its own observations with differential corrections computed from its own past observations; relying on external differential for the sole purpose of establishing a reference location, and this is unlike prior art.

The invention discloses a Beidou three-frequency non-differential non-combined observation value time transmission system and method. The method includes the steps that phase observation value, pseudo-range observation value, satellite ephemeris, earth rotation, antenna phase center and other parameters of China Beidou satellite navigation systems at two time transmission stations are obtained; data check, gross error reject and cycle slip detection are carried out, error models of ephemeris, tide, relativity, the earth rotation, atmosphere and antenna phase deviation are corrected; an ionospheric virtual observation model with additional ionospheric prior information constraints, spatial domain constraints and time domain constraints is constructed; and a three-frequency non-differentialnon-combinatorial precise single-point positioning model is constructed, a single-point positioning timing solution is carried out on corrected data, and comprehensive clock corrections of receivers of the two transmission time stations are obtained and compared to obtain a time transmission difference; and compared with standard time of one of the two transmission time stations, precise time of the other one of the two transmission time stations is obtained. According to the Beidou three-frequency non-differential non-combined observation value time transmission system and method, the observation noise can be reduced, and the accuracy and reliability of time transmission are improved.

The invention discloses a parallel partition electromagnetic transient digital simulation method of an AC and DC power system. The method comprises the following steps of: partitioning a target AC and DC power system into a plurality of subnets comprising an AC network subnet, a current converter subnet, a DC network subnet or an AC and DC mixed network subnet; acquiring equivalent impedance matrix and equivalent potential at port point of each subnet; acquiring current of the tie-line between the subnets; acquiring node voltages of each subnet according to the current of the tie-line between the subnets; solving differential equations of a generator, a control system, and the like of each subnet; processing a user self-defined model, an MATLAB model and input and output information of a physical device; processing input and output information of an electromagnetic transient interface. The simulation method has the advantages of flexible net partition mode, high computation speed, and the like. The simulation method can be simultaneously suitable for electromagnetic transient net partition parallel computation of an AC and DC system, parallel computation of electromechanical transient, accessing a user self-defined model, processing an MATLAB model and a physical device and the like, thereby realizing digital simulation of various transient and dynamic processes of the AC and DC power system.

A device capable of assisting an agent in taking a step even in the case where the leg motion of the agent is stagnant. It is determined whether the agent is in a first state in which the leg of the agent is moving or in a second state in which the leg of the agent is stagnant, on the basis of a value detected in response to the leg motion of the agent. If a transition from the first state to the second state is detected as the determination result, a value of a sustained energy input term is increased, where the sustained energy input term is contained in a simultaneous differential equation representing a second model for use in generating a second oscillator ξ2, which is to be a control basis of an assisting force.

The invention discloses a trajectory tracking control method for a mobile robot based on a sliding mode variable structure. According to the trajectory tracking control method, advantages and disadvantages of different reaching laws are comprehensively analyzed, and a reaching law with better rapidity and stability is proposed and designed. The reaching law is composed of two items, wherein the first item is that the system state is controlled to rapidly approach to a sliding mode surface when being far away from the sliding mode surface, and the second item is that the system state is controlled to keep stable running in the sliding mode surface. The trajectory tracking control method comprises the steps of firstly building a kinematics model and a trajectory tracking error model of the mobile robot, and deducing a mobile robot trajectory tracking error differential equation; and then designing a switching function based on the sliding mode variable structure, and deducing a sliding mode control law according to the designed reaching law, wherein the control law can enable the mobile robot to rapidly converge to an expected trajectory and expected speed. It is indicated by MATLAB numerical simulation that the trajectory tracking control method can effectively weaken a chattering phenomenon in the tracking process and improve the trajectory running accuracy. In addition, the trajectory tracking control method has good stability and robustness.

The invention discloses an analysis method for reducing rolling motion of a ship. The analysis method comprises the following steps of according to an established three-dimensional stimulation image of the ship, calculating instant restoring force and instant wave incidence force of the ship under any waves, calculating a rolling angle and a ship rolling probability according to the ship heaving, pitching and rolling three degrees of freedom coupling motion differential equation to obtain the probability that the rolling angle of the ship is smaller than a flooding angle, thereby judging whether the ship runs at a safe state; and by regulating a navigational state of the ship, obtaining a numerical simulation result of the motion of the ship in any wave directions under the action of random waves and the probability that the rolling angle is smaller than the flooding angle, so that a navigation state of the ship corresponding to the maximum of the probability that the rolling angle is smaller than the flooding angle can be found out, and the rolling motion of the ship can be reduced by selecting the navigation state or changing the model line of a ship body at a design stage. According to the analysis method for reducing the rolling motion of the ship, which is disclosed by the invention, the rolling angle and the rolling probability are calculated, so that the rolling motion of the ship under any waves is reduced.

A method of constructing an image representative of a heterogeneous medium by a procedure of joint inversion of seismic data represented on different time scales having an application for underground reservoir exploration. Sequential inversion of the seismic data is performed so as to determine a first model from the seismic data expressed in a first time scale, and a second model from the seismic data expressed in the second time scale. A scale factor t1(t0) allowing synthetic data described in a first time scale to be expressed in a second time scale is defined by a differential equation relating the traveltime variations of a seismic wave to the models resulting from the sequential inversion. Finally, joint inversion wherein a cost function using the scale factor is minimized is carried out so as to evaluate a difference between the synthetic data and the seismic data expressed in another time scale.

A variable discretization method for general multiphase flow simulation in a producing hydrocarbon reservoir. For subsurface regions for which a regular or Voronoi computational mesh is suitable, a finite difference / finite volume method (“FDM”) is used to discretize numerical solution of the differential equations governing fluid flow (101). For subsurface regions with more complex geometries, a finite element method (“FEM”) is used. The invention combines FDM and FEM in a single computational framework (102). Mathematical coupling at interfaces between different discretization regions is accomplished by decomposing individual phase velocity into an averaged component and a correction term. The averaged velocity component may be determined from pressure and averaged capillary pressure and other properties based on the discretization method employed, while the velocity correction term may be computed using a multipoint flux approximation type method, which may be reduced to two-point flux approximation for simple grid and permeability fields.

A mathematical model specifically for diabetes may be generated which may be continuous in time, in that there are no discrete time steps, and any event can occur at any times. The model may be generated using differential equations, object oriented programming, and features. The model may be used to simulate patients who have contracted or may contract type 1 or type 2 diabetes, which greatly improves the efficiency of treating patients and designing clinical trials.