Recursive least squares-based online nonnegative matrix factorization (rls-ONMF), an NMF algorithm based on the rls method, was developed to solve the NMF problem online. However, this method suffers from a partial-da...
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Recursive least squares-based online nonnegative matrix factorization (rls-ONMF), an NMF algorithm based on the rls method, was developed to solve the NMF problem online. However, this method suffers from a partial-data problem. In this study, the partial-data problem is resolved by developing an improved online NMF algorithm using rls and a sparsity constraint. The proposed method, rls-based online sparse NMF (rls-OSNMF), consists of two steps;an estimation step that optimizes the Euclidean NMF cost function, and a shaping step that satisfies the sparsity constraint. The proposed algorithm was evaluated with recorded speech and music data and with the RWC music database. The results show that the proposed algorithm performs better than conventional rls-ONMF, especially during the adaptation process.
Blind equalization based on adaptive forgetting factor, recursive least squares (rls) with constant modulus algorithm (CMA), is investigated. The cost function of CMA is simplified to meet the second norm form to ...
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Blind equalization based on adaptive forgetting factor, recursive least squares (rls) with constant modulus algorithm (CMA), is investigated. The cost function of CMA is simplified to meet the second norm form to ensure the stability of rls-CMA, and thus an improved rls-CMA (rls-SCMA) is established. To further improve its performance, a new adaptive forgetting factor rls-SCMA (Arls-SCMA) is proposed. In Arls-SCMA, the forgetting factor varies with the output error of the blind equalizer during the iterative process, which leads to a faster convergence rate and a smaller steady-state error. The simulation results prove the effectiveness under the condition of the underwater acoustic channel.
Deadbeat predictive current control (DPCC) is an effective model-based motor control method. However, due to the unbalanced inductance and parameter variations of the segmented powered linear motor stator, the convent...
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Deadbeat predictive current control (DPCC) is an effective model-based motor control method. However, due to the unbalanced inductance and parameter variations of the segmented powered linear motor stator, the conventional model of linear motors is not accurate, which ultimately affect the performance of the control. This paper proposes a novel DPCC based on the recursive least squares (rls) method to identify the parameters of the dual three-phase segmented powered linear motor (SP-LM) model. First, the influence of unbalanced inductance caused by the segmented motor stator and parameter variations of the conventional DPCC are analyzed. Second, a discrete rls model of the dual three-phase SP-LM is established, which is a common model for both linear induction motors (LIMs) and linear synchronous motors (LSMs). Finally, the model parameters are identified by the rls method and the deadbeat principle is used to predict the current. The proposed method effectively eliminates the influence of unbalanced inductance and the parameter variation, improves the current control performance and reduces the thrust fluctuation. Experiments based on hardware-in-the-loop verify the proposed method.
In this paper, a new control mechanism for the variable forgetting factor (VFF) of the recursive least square (rls) adaptive algorithm is presented. The control algorithm is basically a gradient-based method of which ...
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In this paper, a new control mechanism for the variable forgetting factor (VFF) of the recursive least square (rls) adaptive algorithm is presented. The control algorithm is basically a gradient-based method of which the gradient is derived from an improved mean square error analysis of rls. The new mean square error analysis exploits the correlation of the inverse of the correlation matrix with itself that yields improved theoretical results, especially in the transient and steady-state mean square error. It is shown that the theoretical analysis is close to simulation results for different forgetting factors and different model orders. The analysis yields a dynamic equation of mean square error that can be used to derive a dynamic equation of the gradient of mean square error to control the forgetting factor. The dynamic equation can produce a positive gradient when the error is large and a negative gradient when the error is in the steady state. Compared with other variable forgetting factor algorithms, the new control algorithm gives fast tracking and small mean square model error for different signal-to-noise ratios (SNRs).
The ExoMars rover, scheduled to be launched in 2020, will be equipped with a novel and diverse payload. It will also include a drill to collect subsurface samples (from 0- to 2-m depth) and deliver them to the rover a...
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The ExoMars rover, scheduled to be launched in 2020, will be equipped with a novel and diverse payload. It will also include a drill to collect subsurface samples (from 0- to 2-m depth) and deliver them to the rover analytical laboratory, where it will be possible to perform combined science between instruments. For the first time, the exact same sample target areas will be investigated using complementary analytical methods-infrared spectrometry, Raman spectrometry, and laser desorption mass spectrometry-to establish mineralogical and organic chemistry composition. Fundamental for implementing this cooperative science strategy is the Raman Laser Spectrometer (rls) calibration target (CT). The rls CT features a polyethylene terephthalate disk used for rls calibration and verification of the instrument during the mission. In addition, special patterns have been recorded on the rls CT disk that the other instruments can detect and employ to determine their relative position. In this manner, the rls CT ensures the spatial correlation between the three analytical laboratory instruments: MicrOmega, rls, and MOMA. The rls CT has been subjected to a series of tests to qualify it for space utilization and to characterize its behavior during the mission. The results from the joint work performed by the rls and MicrOmega instrument teams confirm the feasibility of the "combined science" approach envisioned for ExoMars rover operations, whose science return is optimized when complementing the rls and MicrOmega joint analysis with the autonomous rls operation.
A new fast recursive least squares (rls) algorithm is introduced. By making use of rls interpolation as well as prediction, the algorithm generates the transversal filter weights without suffering the poor numerical a...
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A new fast recursive least squares (rls) algorithm is introduced. By making use of rls interpolation as well as prediction, the algorithm generates the transversal filter weights without suffering the poor numerical attributes of the FTF algorithm. The Kalman gain vector is generated at each time step in terms of interpolation residuals. The interpolation residuals are calculated in an order recursive manner. For an Nth-order problem, the procedure requires O(N log(2) N) operations per iteration. This is achieved via a divide-and-conquer approach. Computer simulations suggest that the new algorithm is numerically robust, running successfully for many millions of iterations.
Group sparsity is one of the important signal priors for regularization of inverse problems. Sparsity with group structure is encountered in numerous applications. However, despite the abundance of sparsity-based adap...
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Group sparsity is one of the important signal priors for regularization of inverse problems. Sparsity with group structure is encountered in numerous applications. However, despite the abundance of sparsity-based adaptive algorithms, attempts at group sparse adaptive methods are very scarce. In this paper, we introduce novel recursive least squares (rls) adaptive algorithms regularized via penalty functions, which promote group sparsity. We present a new analytic approximation for (p,0) norm to utilize it as a group sparse regularizer. Simulation results confirm the improved performance of the new group sparse algorithms over regular and sparse rls algorithms when group sparse structure is present. Copyright (c) 2013 John Wiley & Sons, Ltd.
In this letter, the rls adaptive algorithm is considered in the system identification setting. The rls algorithm is regularized using a general convex function of the system impulse response estimate. The normal equat...
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In this letter, the rls adaptive algorithm is considered in the system identification setting. The rls algorithm is regularized using a general convex function of the system impulse response estimate. The normal equations corresponding to the convex regularized cost function are derived, and a recursive algorithm for the update of the tap estimates is established. We also introduce a closed-form expression for selecting the regularization parameter. With this selection of the regularization parameter, we show that the convex regularized rls algorithm performs as well as, and possibly better than, the regular rls when there is a constraint on the value of the convex function evaluated at the true weight vector. Simulations demonstrate the superiority of the convex regularized rls with automatic parameter selection over regular rls for the sparse system identification setting.
This paper presents a technique for the removal of ocular artifacts from electro-encephalogram (EEG) by using adaptive filtering. The major concern is electro-oculogram (EOG) signal present in a recorded EEG signal, w...
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This paper presents a technique for the removal of ocular artifacts from electro-encephalogram (EEG) by using adaptive filtering. The major concern is electro-oculogram (EOG) signal present in a recorded EEG signal, which appears due to abrupt eye movements. In the presented method, we use separately recorded horizontal EOG (HEOG) and vertical EOG (VEOG) signals as two reference inputs, which are processed using finite impulse response (FIR) filters. The linear filter coefficients are adaptively updated using a numerical variable forgetting factor (NVFF) recursive least squares (rls) algorithm, which tracks nonstationary EOG signals. Subsequently, the processed HEOG and VEOG signals are subtracted from recorded EEG signal to obtain an artifact-free EEG signal. Simulation is conducted using synthetic EEG signal corrupted by noise, synthetic HEOG and VEOG signals. The real-time recorded EEG signal (corrupted by EOG and noise) is also refined using the separately recorded reference EOG signals and FIR filtering technique. For synthetic and real-time signals, the simulation results are presented to demonstrate that linear NVFF-rls algorithm-based artifact and noise excision technique outperforms conventional fixed forgetting factor rls, fixed step-size NLMS and generalized variable step-size NLMS algorithms, in terms of the reduction in mean-squared error, under low as well as high signal-to-noise ratio conditions.
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