We give an algorithm to compute inhomogeneous differential equations for definite integrals with parameters. The algorithm is based on the integration algorithm for D-modules by Oaku. Main tool in the algorithm is the...
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ISBN:
(纸本)9783642155819
We give an algorithm to compute inhomogeneous differential equations for definite integrals with parameters. The algorithm is based on the integration algorithm for D-modules by Oaku. Main tool in the algorithm is the Grobner basis method in the ring of differential operators.
SINSIGPS integration provides reliable navigation solutions by overcoming each of their shortcomings, including signal blockage for GPS and growth of position errors with time for SINS. Most of the present navigation ...
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ISBN:
(纸本)1424403316
SINSIGPS integration provides reliable navigation solutions by overcoming each of their shortcomings, including signal blockage for GPS and growth of position errors with time for SINS. Most of the present navigation systems rely on Kalman filtering methods to fuse data. Present Kalman filtering SINS/GPS integration techniques have several inadequacies related to sensor error model, immunity to noise and observability. This paper aims at introducing a novel SINS/GPS integration algorithm utilizing Hopfield neural network. This method obtains the optimal state estimation by minimizing the energy function of the Hopfield neural network. Furthermore this algorithm relaxes the assumptions made by the Kalman filter so that it is more versatile. Simulation results show that the new integration algorithm performs similarly to the Kalman filter. Furthermore it has some advantages such as fast convergence, unbias and high precision during fusion process, despite of the inaccurate modeling errors, system disturbance, observation errors, and even the shortage of observation. Also as the parallel computational mode and easily carried out in hardware of the Hopfield neural network, this integration algorithm can improve the navigation guidance accuracy, real time ability and practicability of the SINS/GPS.
A parabolic interpolation function of time is proposed to evaluate the non-adiabatic coupling matrix elements and the adiabatic energies at intermediate times within the classical time integration interval in hybrid q...
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A parabolic interpolation function of time is proposed to evaluate the non-adiabatic coupling matrix elements and the adiabatic energies at intermediate times within the classical time integration interval in hybrid quantum/classical simulations. The accuracy and the computational efficiency of this parabolic approximation are illustrated by carrying out a numerical application to the well-studied vibrational relaxation of l(2) in liquid xenon. (c) 2008 Elsevier B.V. All rights reserved,
The reference wave phase was modulated with a sinusoidal vibrating mirror attached to a Piezoelectric Transducer (PZT), the integration was performed by a CCD, and the charge storage period of the CCD image sensor was...
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ISBN:
(纸本)9780819474001
The reference wave phase was modulated with a sinusoidal vibrating mirror attached to a Piezoelectric Transducer (PZT), the integration was performed by a CCD, and the charge storage period of the CCD image sensor was one-quarter period of the sinusoidal phase modulation. With the frequency-synchronous detection technique, four images (four frames of interference pattern) were recorded during one period of the phase modulation. In order to obtain the optimum modulation parameter, the values of amplitude and phase of the sinusoidal phase modulation were determined by considering the measurement error caused by the additive noise contained in the detected values. The PZT oscillation was controlled by a closed loop control system based on PID controller. An ideal discrete digital sine function at 50Hz with adjustable amplitude was used to adjust the vibrating of PZT, and a digital phase shift techniques was used to adjust vibrating phase of PZT so that the phase of the modulation could reach their optimum values. The CCD detector was triggered with software at 200Hz. Based on work above, a small coherent signal masked by the preponderant incoherent background with a CCD detector was obtained.
Real-time hybrid testing is a method that combines experimental substructure(s) representing component(s) of a structure with a numerical model of the remaining part of the structure. These substructures are combined ...
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Real-time hybrid testing is a method that combines experimental substructure(s) representing component(s) of a structure with a numerical model of the remaining part of the structure. These substructures are combined with the integration algorithm for the test and the servo-hydraulic actuator to form the real-time hybrid testing system. The inherent dynamics of the servo-hydraulic actuator used in real-time hybrid testing will give rise to a time delay, which may result in a degradation of accuracy of the test, and possibly render the system to become unstable. To acquire a better understanding of the stability of a real-time hybrid test with actuator delay, a stability analysis procedure for single-degree-of-freedom structures is presented that includes both the actuator delay and an explicit integration algorithm. The actuator delay is modeled by a discrete transfer function and combined with a discrete transfer function representing the integration algorithm to form a closed-loop transfer function for the real-time hybrid testing system. The stability of the system is investigated by examining the poles of the closed-loop transfer function. The effect of actuator delay on the stability of a real-time hybrid test is shown to be dependent on the structural parameters as well as the form of the integration algorithm. The stability analysis results can have a significant difference compared with the solution from the delay differential equation, thereby illustrating the need to include the integration algorithm in the stability analysis of a real-time hybrid testing system. Copyright (C) 2007 John Wiley & Sons, Ltd.
When solving the problem in Computer Assisted Detection by the approach of Pattern Recognition, the lesion data always exhibited high-dimensional and inhomogeneous, which makes most of the traditional classifiers can ...
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ISBN:
(纸本)9781424441990
When solving the problem in Computer Assisted Detection by the approach of Pattern Recognition, the lesion data always exhibited high-dimensional and inhomogeneous, which makes most of the traditional classifiers can not performance very well. In this paper, a novel approach based on the Dynamic Feature Subset Selection and the EM algorithm with Naive Bayesian classifier integration algorithm (DSFS+EMNB) is proposed. The experimental results demonstrated that this method significantly outperforms the other methods like SVM and other traditional classification methods in terms of average accuracy, as well as generality.
This article deals with a viscoplastic material model of overstress type. The model is based on a multiplicative decomposition of the deformation gradient into elastic and inelastic part. An additional multiplicative ...
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This article deals with a viscoplastic material model of overstress type. The model is based on a multiplicative decomposition of the deformation gradient into elastic and inelastic part. An additional multiplicative decomposition of inelastic part is used to describe a nonlinear kinematic hardening of Armstrong-Frederick type. Two implicit time-stepping methods are adopted for numerical integration of evolution equations, such that the plastic incompressibility constraint is exactly satisfied. The first method is based on the tensor exponential. The second method is a modified Euler-backward method. Special numerical tests show that both approaches yield similar results even for finite inelastic increments. The basic features of the material response, predicted by the material model, are illustrated with a series of numerical simulations. (C) 2008 Elsevier B.V. All rights reserved.
The present paper focuses on the application of line-search methods in general return mapping algorithms. Two inexact line-search methods and an exact line-search method are investigated regarding their convergence pr...
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The present paper focuses on the application of line-search methods in general return mapping algorithms. Two inexact line-search methods and an exact line-search method are investigated regarding their convergence properties within an automatic time incrementation in finite element calculations. As an example for the assessment of the algorithms, an elastic-plastic and an elastic-viscoplastic version of Gurson's porous plasticity model are used in simulations of the necking of a tensile bar. It is shown that larger time increments are possible and, therefore, a smaller number of increments are required when using line-search methods. The exact line-search method shows the best performance concerning the required number of increments, but takes more CPU time to complete the simulation. The application of the inexact line search methods in general lowers the number of increments along with a reduction in the CPU time, as compared with the case when no line-search is used. Copyright (c) 2007 John Wiley & Sons, Ltd.
Nonlinear viscoelastic response of reinforced elastomers is modeled using a three-dimensional mixed finite element method with a nonlocal pressure field. A general second-order unconditionally stable exponential integ...
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Nonlinear viscoelastic response of reinforced elastomers is modeled using a three-dimensional mixed finite element method with a nonlocal pressure field. A general second-order unconditionally stable exponential integrator based on a diagonal Pade approximation is developed and the Bergstrom-Boyce nonlinear viscoelastic law is employed as a prototype model. An implicit finite element scheme with consistent linearization is used and the novel integrator is successfully implemented. Finally, several viscoelastic examples, including a study of the unit cell for a solid propellant, are solved to demonstrate the computational algorithm and relevant underlying physics. (c) 2008 Elsevier B.V. All rights reserved.
An efficient numerical algorithm for modeling of cyclic elastoplastic deformation of shell structures is derived. The constitutive model includes highly nonlinear multi-component forms of kinematic and isotropic harde...
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An efficient numerical algorithm for modeling of cyclic elastoplastic deformation of shell structures is derived. The constitutive model includes highly nonlinear multi-component forms of kinematic and isotropic hardening functions in conjunction with von Mises yield criterion. Therein, the closest point projection algorithm employing the Reissner-Mindlin type kinematic model, completely formulated in tensor notation, is applied. A consistent elastoplastic tangent modulus ensures high convergence rates in the global iteration approach. The integration algorithm has been implemented into a layered assumed strain isoparametric finite shell element, which is capable of geometrical nonlinearities including finite rotations. Numerical examples, considering the symmetric and nonsymmetric loading controlled tests, illustrate the ratcheting effect and stabilization of the load-displacement response. Accuracy and robustness of the proposed algorithms are demonstrated.
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