A lattice Boltzmann method on nonuniform quadtree grids is proposed. Our method employs the interpolation-supplemented lattice Boltzmann model. The advantages of the quadtree grid are preserved by using linear interpo...
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A lattice Boltzmann method on nonuniform quadtree grids is proposed. Our method employs the interpolation-supplemented lattice Boltzmann model. The advantages of the quadtree grid are preserved by using linear interpolation instead of quadratic interpolation to complete the streaming step in the lattice Boltzmann method. The back-and-forth error compensation and correction (BFECC) method is used to improve the accuracy, so that the second-order accuracy of the conventional lattice Boltzmann method is maintained. Several numerical cases, including a BFECC streaming test, lid-driven cavity flow, and flow over an asymmetrically placed cylinder in a channel, are carried out to demonstrate the accuracy and efficiency of our method.
Abstract The regression problem of fitting a “smooth”, discrete curve to data points on a Riemannian manifold is formulated here as an unconstrained, finite-dimensional optimization problem. Smoothness of a discrete...
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In this paper a new efficient algorithm for spherical interpolation of large scattered data sets is presented. The solution method is local and involves a modified spherical Shepard's interpolant, which uses zonal...
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In this paper a new efficient algorithm for spherical interpolation of large scattered data sets is presented. The solution method is local and involves a modified spherical Shepard's interpolant, which uses zonal basis functions as local approximants. The associated algorithm is implemented and optimized by applying a nearest neighbour searching procedure on the sphere. Specifically, this technique is mainly based on the partition of the sphere in a suitable number of spherical zones, the construction of spherical caps as local neighbourhoods for each node, and finally the employment of a spherical zone searching procedure. Computational cost and storage requirements of the spherical algorithm are analyzed. Moreover, several numerical results show the good accuracy of the method and the high efficiency of the proposed algorithm. (C) 2010 Elsevier BM. All rights reserved.
The evaluation of the spectral components of a signal by means of a DFT or FFT algorithm is subject to leakage errors whenever the sampling frequency is not coherent with the signal frequency. Smoothing windows are us...
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ISBN:
(纸本)9781424428335
The evaluation of the spectral components of a signal by means of a DFT or FFT algorithm is subject to leakage errors whenever the sampling frequency is not coherent with the signal frequency. Smoothing windows are used to mitigate these errors, and interpolation methods are applied, in the frequency domain, to reduce these errors further on. However, if cosine windows are employed, closed-form formulas for the evaluation of the harmonic frequencies can be used only with second-order windows, while approximated formulas have to be used in the other cases. In both cases, a high computation burden is required. This paper proposes a fast interpolation method, independent of the window type and order, based on suitable look-up tables. Experimental results are reported and the accuracy is discussed, proving that the method provides results as good as those obtained with other methods, without requiring the same high computation burden.
In this paper, we propose the Fourier series interpolation (FSI) method for the solution of the SDARE* in which the state dependency of the coefficient matrices is of periodic nature. In particular, we focus on the SD...
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ISBN:
(纸本)9781627481199
In this paper, we propose the Fourier series interpolation (FSI) method for the solution of the SDARE* in which the state dependency of the coefficient matrices is of periodic nature. In particular, we focus on the SDAREs where the system matrix depends on a single state component in a periodic way. The main advantage of the FSI approach is that the Fourier coefficients are computed offline. This in turn results in significant reduction in online computations for the solution of the SDARE. The implementation and performance of the FSI method is explained by considering the dynamical positioning (DP) problem of a ship. This problem has been studied by using the SDARE controller and observer. This requires online computation of the solution of the SDAREs. We show that the FSI method significantly reduces the online computation time in comparison with the MATLAB routine “care” in a situation where online solution of the SDARE is required. The FSI method can be particularly useful in situations involving the systems having small time constants.
The majority of GIS type software systems allow generating the digital terrain models on the basis of the regular GRID type network of squares. The accuracy of such a model depends mainly on the choice of interpolatio...
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ISBN:
(纸本)9789955282631
The majority of GIS type software systems allow generating the digital terrain models on the basis of the regular GRID type network of squares. The accuracy of such a model depends mainly on the choice of interpolation algorithms and their computation parameters. Comparison of quality and accuracy of the interpolation models generated by applying different algorithms is becoming an important issue. The paper presents a comparison of accuracy of terrain models generated by application of five interpolation algorithms. The analysis was based on the theoretical model represented by the mathematical surface generated using the function of two variables. Selected statistical coefficients and differential diagram of errors distribution were applied for interpolation models accuracy comparison. The matching accuracy of interpolation surface and the standard surface was also investigated. Results of analysis of the values determined by statistical coefficients supported with differential diagrams allowed comprehensive comparison of accuracy of interpolation algorithms and identification of the most accurate among them.
The method of harmonious detecting is introduced about PV grid connected generation, and the technique is realized to harmonious synchronous sampling based on PLL circuit of hardware, in order that the error is elimin...
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ISBN:
(纸本)9787900719706
The method of harmonious detecting is introduced about PV grid connected generation, and the technique is realized to harmonious synchronous sampling based on PLL circuit of hardware, in order that the error is eliminated for non-synchronous sampling at all. It is used to analyze the harmonic of PV system for FFT algorithm based on B-H window function and interpolation, and the error is minished by frequency table giveaway and barrier domino offect effectively, veracity of data processing is advanced.
The position was one of the first parameters that required the introduction of automatic control process. One of the most representative applications is represented by the feed drives of the computer numerically contr...
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The position was one of the first parameters that required the introduction of automatic control process. One of the most representative applications is represented by the feed drives of the computer numerically controlled (CNC) machine tools. Today, it is possible to use computer simulation techniques in analysing and synthesising position control systems. Thus, the behaviour of the CNC machine tools feed drives can be treated much more realistically. It is the purpose of this paper to show how simulation can be used to accurately represent, predict and improve the performance of a CNC machine tool feed servo drives.
Modern high speed machining (HSM) machine tools often operates at high speed and high feedrate with high accelerations, in order to deliver the rapid feed motion. This paper presents an interpolation algorithm to gene...
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Modern high speed machining (HSM) machine tools often operates at high speed and high feedrate with high accelerations, in order to deliver the rapid feed motion. This paper presents an interpolation algorithm to generate continuous quintic spline toolpaths, with a constant travel increment at each step, while the smoother accelerations and jerks of two-order curve are obtained. Then an approach for reducing the feedrate fluctuation in high speed spline interpolation is presented. The presented approach has been validated to quickly, reliably and effective with the simulation.
In order to help researcher to understand the measuring data more carefully, and to obtain more valuable and significant information hidden in measuring data of water environmental hydrodynamics, a ne
In order to help researcher to understand the measuring data more carefully, and to obtain more valuable and significant information hidden in measuring data of water environmental hydrodynamics, a ne
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