34results about How to "Reduce truncation error" patented technology

An apparatus, method and program storage device for determining high-energy neutron / ion transport to a target of interest. Boundaries are defined for calculation of a high-energy neutron / ion transport to a target of interest; the high-energy neutron / ion transport to the target of interest is calculated using numerical procedures selected to reduce local truncation error by including higher order terms and to allow absolute control of propagated error by ensuring truncation error is third order in step size, and using scaling procedures for flux coupling terms modified to improve computed results by adding a scaling factor to terms describing production of j-particles from collisions of k-particles; and the calculated high-energy neutron / ion transport is provided to modeling modules to control an effective radiation dose at the target of interest.

A local extremum of a function ƒ is determined by computing a Jacobian of ƒ at a test point x by adding an imaginary part to x and a Hessian of ƒ by adding two imaginary parts to a multicomplex copy of x and extracting a third imaginary part. Solving a system of equations defined by the Jacobian and Hessian yields a delta; the process is repeated until convergence. This method is used in each of a series of time intervals to compute an insulin-delivery amount for an insulin pump. ƒ is a model-predictive-control cost function; x is a set of successive candidate insulin delivery amounts beginning from a selected time interval. A system includes a glucose monitor and a controller using glucose measurement data therefrom to determine an insulin delivery amount for a time interval by minimizing ƒ; an insulin pump provides insulin corresponding to the delivery amount.

The invention discloses a double-rate Kalman filtering method based on GNSS / INS deep integrated navigation. The method comprises the following steps of 1, building a state equation according to the initial position, the rate and the attitude information of a carrier, and initializing the parameters of the Kalman filtering; 2, performing state prediction updating on M step lengths and obtaining a predicted value of a prior state quantity which is described in the specification; 3 correcting the prior state quantity which is described in the specification to obtain a predicted value of a posterior state quantity which is described in the specification; 4, adaptively updating the errors of the state quantities and a systematic error covariance matrix, and compensating an inertial navigation result by using the predicted value of the posterior state quantity which is described in the specification to obtain the position, the rate and attitude information of the carrier; and 5, updating thepredicted value of a posterior state quantity which is described in the specification after the compensation. The method can reduce a truncation error caused by the low update frequency of GNSS satellite data or the losing lock of the satellite data during a data fusion algorithm of the GNSS / INS deep integrated navigation, and simultaneously solve a navigation positioning error caused by the non-synchronization of INS data and GNSS data.

The invention relates to a state estimation method based on high-order unscented Kalman filtering. A high-order unscented Kalman filter is used for finishing the state estimation task in the target tracking process. According to the state estimation method based on the high-order unscented Kalman filtering, the state estimation task in the target tracking process is finished by the high-order unscented Kalman filter. In the target tracking process, the state equation and the measurement equation of target tracking are established; a sigma point required for the target tracking filter is obtained by high-order unscented transformation, and the weight of the sigma point is calculated; and the state estimation is obtained by iterating the sigma point and the weight of the sigma point to realize the real-time tracking of the target. The tracking precision of the state estimation method is higher than those of the existing target tracking methods based on other filters, a proper performance parameter k is selected to further improve the precision of the proposed high-order unscented Kalman filtering (UKF) target tracking method, and the high-precision real-time tracking to the target is realized. The state estimation method disclosed by the invention is applied to the technical field of the target tracking.

The invention relates to an electromagnetic transient simulation method including a switch characteristic branch, and belongs to the technical field of electromagnetic transient analysis of power systems. In this method, circuit breakers and power electronic switching elements are designed into a single switch sub-network, and the network only includes power electronic switches, circuit breakers and their related components (resistance, inductance, capacitance, etc.). The approximate exponential fitting method is used for modeling, and the rest of the network is modeled by conventional methods (implicit trapezoidal method, backward Euler method, trapezoidal method with damping or its modified combination). In offline / real-time calculation, only the switch sub-network performs iteration or interpolation calculation, and the rest of the network does not participate in iteration or interpolation. Since the switch sub-network adopts the high-order algorithm proposed by the present invention, it can be immune to numerical oscillation, and at the same time, because the workload of modifying the model is small, it is beneficial to engineering popularization and realization.

A method for constructing a new WENO scheme under the framework of trigonometric functions. On the one hand, the weighted basic non-oscillating scheme constructed with trigonometric polynomials is easier to simulate wave or high-frequency oscillation problems than the classical basic non-oscillating scheme constructed with algebraic polynomials. The smooth region can obtain high-order numerical accuracy, and maintains the property of basically no oscillation at the shock wave and contact discontinuity; on the other hand, although the new TWENO format uses the same five-point information as the classic fifth-order WENO format, it can get lower global L 1 and L ∞ Norm truncation error. The linear weight adopted by the new TWENO format no longer needs to obtain the optimal solution through cumbersome numerical calculations, and can be set to any positive number that satisfies the sum to be one. Compared with the classic WENO format, it is simpler, more robust, and easier Generalized to high-dimensional space. The new TWENO scheme effectively simulates several classical Euler problems numerically, and fully verifies the effectiveness.

The invention relates to a 0+ error immune electromagnetic transient simulation algorithm used under the sudden change of input quantity and belongs to the technical field of electromagnetic transient analysis of an electric system. According to the method, by means of the impulse response invariable principle, numerical sampling of a continuous signal of the system corresponds to Z conversion of a discrete signal, and the fundamental form of an element based on operation conductance and a history current item is given. Based on the form, a system network equation is obtained according to the node analysis method, and a system electromagnetic transient simulation result is obtained according to the same steps. The method has the advantages that the truncation error is smaller than that generated through currently adopted methods and the 0+ error purpose is realized under the sudden change of the immune input quantity, achieves non-linear load modeling of the electric system, solves the problem of oscillation of an electronic power switch model state variable outburst value, and provides a new way for electromagnetic transient branch-level modeling of the electric system.

The invention relates to a six-degree-of-freedom position and attitude determination method based on road sign navigation, which belongs to the field of information processing in an automatic control system. According to the coupling between the position element and the attitude element in the pixel observation equation, the invention considers the invariance of the angle under the Euclidean transformation, and takes the angle formed between the observation sight lines of each navigation road sign as the observation amount, and uses the position and attitude in the pixel observation equation. State decoupling, solves the position and attitude states in the pixel observation equation separately, reduces the complexity of the algorithm, quickly determines the result and improves the solution accuracy. The applicability of this method can also be extended from 3 navigation landmarks to multiple landmarks.