Accurate and efficient schemes for interpolating and filtering/anterpolating far field radiation patterns are key to the operation of the multilevel fast multipole method (FMM) (Song, J.M. et al., IEEE Trans. Antennas...
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ISBN:
(纸本)0780383028
Accurate and efficient schemes for interpolating and filtering/anterpolating far field radiation patterns are key to the operation of the multilevel fast multipole method (FMM) (Song, J.M. et al., IEEE Trans. Antennas and Propag., vol.45, p.1488-93, 1997) and plane wave time domain (PWTD) (Shanker, B. et al., IEEE Trans. Antennas and Propag., vol.51, 2003) accelerated frequency and time domain integral equation solvers. Local interpolators and filters/anterpolators, like those used by Song et al., offer distinct advantages over their global counterparts (Shanker et al., 2003; Sarvas, J., 2002), especially in parallel implementations. We propose a simple local filtering scheme suitable for incorporation into FMM and PWTD field evaluation kernels. The filter relies on periodic approximate prolate spheroidal (APS) functions (Bucci, O.M. et al., 1991) to restrict coupling among radiation directions. A numerical example shows that the error due to the proposed local filtering scheme decays exponentially fast with respect to the oversampling and "time-bandwidth" factors that define the periodic APS function and can be made arbitrarily small.
As one of the most successful recommender systems, collaborative filtering (CF) algorithms can deal with high sparsity and high requirement of scalability amongst other challenges. Bayesian belief nets (BNs), one of t...
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As one of the most successful recommender systems, collaborative filtering (CF) algorithms can deal with high sparsity and high requirement of scalability amongst other challenges. Bayesian belief nets (BNs), one of the most frequently used classifiers, can be used for CF tasks. Previous works of applying BNs to CF tasks were mainly focused on binary-class data, and used simple or basic Bayesian classifiers (Miyahara and Pazzani, 2002; Breese et al., 1998). In this work, we apply advanced BNs models to CF tasks instead of simple ones, and work on real-world multi-class CF data instead of synthetic binary-class data. Empirical results show that with their ability to deal with incomplete data, extended logistic regression on naive Bayes and tree augmented naive Bayes (NB-ELR and TAN-ELR) models (Greiner et al., 2005) consistently perform better than the state-of-the-art Pearson correlation-based CF algorithm. In addition, the ELR-optimized BNs CF models are robust in terms of the ability to make predictions, while the robustness of the Pearson correlation-based CF algorithm degrades as the sparseness of the data increases
The objective of this paper is to analyze some factors influencing the performance of different farmer parallel programs, developed for the hierarchical Kalman filtering. During our research we systematically modified...
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The objective of this paper is to analyze some factors influencing the performance of different farmer parallel programs, developed for the hierarchical Kalman filtering. During our research we systematically modified a number of hardware and/or software parameters which characterize the farmer and we have shown that these modifications has a reduced influence to linear speed-up rate.
In this paper, we overview the low complexity recursive L 1 -Regularized Least Squares (SPARLS) algorithm proposed in [2], for the estimation of sparse signals in an adaptive filtering setting. The SPARLS algorithm is...
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In this paper, we overview the low complexity recursive L 1 -Regularized Least Squares (SPARLS) algorithm proposed in [2], for the estimation of sparse signals in an adaptive filtering setting. The SPARLS algorithm is based on an Expectation-Maximization type algorithm adapted for online estimation. Simulation results for the estimation of multi-path wireless channels show that the SPARLS algorithm has significant improvement over the conventional widely-used Recursive Least Squares (RLS) algorithm, in terms of both mean squared error (MSE) and computational complexity.
This paper proposes an approach for the derivation of optimal algorithms for max/min filtering. The transfer matrix for the input-output description of max/min filters is introduced. In connection with the filter real...
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This paper proposes an approach for the derivation of optimal algorithms for max/min filtering. The transfer matrix for the input-output description of max/min filters is introduced. In connection with the filter realization problem, the decomposition of transfer matrices is analyzed. The decomposition is based on two properties, namely chaining and weak superposition. Matrix decomposition is further used to derive flow-charts for max/min computation. Optimization criteria with respect to the computational complexity (comparisons/sample) of the derived algorithms are defined. Two examples are presented. For certain window sizes, the derived algorithms perform in less than log/sub 2/n comparisons per sample.
An algorithm for total least squares filtering is developed based on a gradient descent approach. The total least squares approach can mitigate parameter estimation bias resulting from noise effects in the adaptive fi...
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ISBN:
(纸本)0780365143
An algorithm for total least squares filtering is developed based on a gradient descent approach. The total least squares approach can mitigate parameter estimation bias resulting from noise effects in the adaptive filter. The stability properties of the algorithm are analyzed and stable and convergent behavior is established The proposed algorithm is implemented without divisions or square roots, and does not require normalization. Despite recent interest in iterative total least squares methods, there are few algorithms that both avoid the computational complexities described above and have been shown to possess stable and convergent behavior.
A nonlinear adaptive filter for use in steel mill applications is described. This filter takes the form of a generalised regression network and is used to remove eccentricities from a steel mill force signal. Online a...
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A nonlinear adaptive filter for use in steel mill applications is described. This filter takes the form of a generalised regression network and is used to remove eccentricities from a steel mill force signal. Online adaptation is achieved by means of standard recursive parameter update algorithms suitable for linear regression type models. It is demonstrated that second order methods can lead to severe parameter biasing effects and a more serious effect known as bursting, whereby the parameter estimation becomes numerically unstable. This paper discusses the above effects form a theoretical and practical viewpoint, and considers the suitability of several learning algorithms for the eccentricity filtering application. This analysis leads to a numerically robust filtering structure, the efficacy of which is demonstrated by means of results from a real steel rolling mill.
The disconnector operation in the high-voltage substations forms a very fast transient overvoltage (VFTO), which leads to a sudden rise in local grounding potential. Due to double grounding of the secondary cable, the...
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The disconnector operation in the high-voltage substations forms a very fast transient overvoltage (VFTO), which leads to a sudden rise in local grounding potential. Due to double grounding of the secondary cable, the current transformer signal is interfered by the grounding grid potential difference. To study the mechanism of the interference signal, a simulation model based on the electro-magnetic transient program is built and the coupling path of the grounding grid potential difference is analyzed. According to the characteristics of interference signal, an adaptive algorithm is put forward and it mainly consists of three parts, including starting element, decision algorithm, and filtering algorithm. By selecting the appropriate parameters of wavelet transform, the filtering algorithm can discompose and reconstruct signal to remove the interference signal. The simulation results demonstrate that the filtering algorithm can effectively eliminate the interference signal caused by the grounding grid potential difference, with a 91 reduction of the root mean square error and a 135 improvement of the signal-to-noise ratio. Moreover, the accuracy of the measured data is ensured and the reliability of the relay protection is improved.
The problem of a slow varying phase noise (PN) estimation at a low signal to noise ratio (SNR) in a non-pilot aided receiver is considered. Two iterative algorithms using Kalman filtering are proposed to estimate the ...
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The problem of a slow varying phase noise (PN) estimation at a low signal to noise ratio (SNR) in a non-pilot aided receiver is considered. Two iterative algorithms using Kalman filtering are proposed to estimate the PN under the expectation-maximization (EM) framework. The first algorithm uses a soft decision directed extended Kalman smoother (EKS) to provide a suboptimal PN estimate. While the second algorithm overcomes the nonlinear structure of the EKS and improves the PN estimate by using a Kalman smoother (KS) which is applied assuming small PN values. An enhanced KS is proposed to maintain the KS performance in large PN values. Simulation results show that the performance of the proposed algorithms is close to the performance of the synchronized system with no PN effect.
Lattice-form algorithms are described for adaptive IIR (infinite-impulse-response) filtering that are based on the Gauss-Newton search method. Several approximations of the Hessian matrix that have different levels of...
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Lattice-form algorithms are described for adaptive IIR (infinite-impulse-response) filtering that are based on the Gauss-Newton search method. Several approximations of the Hessian matrix that have different levels of computational complexity are considered, and the results are compared to a previous IIR lattice algorithm. Computer simulations in a system-identification configuration illustrate their convergence properties. algorithms for the two-multiplier lattice with distinct coefficients in each section, and the one-multiplier form, are outlined.< >
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