Introduction The analysis of electrocardiogram (ECG) signals allows experts to diagnose several cardiac disorders. However, the accuracy of such diagnosis depends heavily on the signal quality. In this paper, an efficient method based on fractional wavelet decomposition coupled with thresholding techniques is proposed for noise removal. Methods The usual low-pass and high-pass filters of the wavelet transform are replaced by fractional-order ones. Thus, fractional wavelets are proposed, simulated, and compared to other wavelets for ECG denoising. The denoising process was made operational by the means of an appropriate choice of the wavelet transform coefficient thresholding and the wavelet decomposition level of the signal. Results Considering the relative error metrics, the best wavelet function for efficient denoising is the fractional one. In our study, we have used eight real ECG signals from the Physionet MITBIH. In order to prove the effectiveness of our method, we investigated the filtering of two types of noises, namely Gaussian white noise and power-line interference (PLI) noise. The proposed method removed the Gaussian white noise completely and had better performance on the PLI noise. Considering classical metrics of assessment, results show the advantage of the proposed method compared to other types of wavelets. Conclusion The proposed method is the most suitable one for removing PLI and Gaussian white noise from ECG signals with superior performance than other wavelets. Also, it can be applied for high-frequency denoising even without a priori frequency knowledge.

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A new direct adaptive type-2 fuzzy controller for a nonlinear dynamical system is developed in this paper. The parameters of the membership functions characterizing the linguistic terms in the type-2 fuzzy IF–THEN rules change according to some adaptive law for the purpose of controlling a plant to track a reference trajectory. A supervisory controller is appended to the type-2 fuzzy controller to force the state to be within the constraint set. Stability of this adaptive scheme is established using Lyapunov stability tools, where we guarantee the global stability of the resulting closed-loop system, in the sense that all signals involved are uniformly bounded. The simulation results for a Duffing forced-oscillation system show better performances, i.e. tracking error and control effort can be made smaller.

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Swimming microrobots have been broadly considered and drawn great attention for the mainly recent years, in robotics and biomedical domains, due to their alternative applications. This work models and optimizes a new swimming microrobot design for biomedical applications. The key idea behind this contribution is to find out the best dimension and electromechanical parameters of the investigated swimming microrobot that will yield the maximum thrust force for reliable swimming microrobot applications. The analytical models are developed to calculate the thrust force generated by a hybrid tail. The microrobot is modulated using a nonlinear model-based approach for magnetical control. We show that our proposed device can be significantly improved by using the IPCM hybrid tails with thick link at the end of the tail. Furthermore, the artificial bee colony algorithm is used to ameliorate both, electromechanical parameters and the microrobot geometrical aspect, in order to enhance the performance and robustness behavior of the investigated microrobot. In this context, thrust force of the investigated structure is examined and compared with the conventional microrobots. The obtained results demonstrate that the proposed design can be considered as a potential candidate for high performance microrobot-based applications.

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The presented method is a DCT mitigation thresholding technique (DCT-MTT) for narrowband interference reduction in Global Navigation Satellite System (GNSS) receivers. First, the received signal immersed in an Additive White Gaussian Noise (AWGN), is multiplied, in time domain, (sample by sample) by a Tukey window of the same length. Then, the DCT transform is applied. Next, the transformed signal is divided in nonoverlapped packets. Each one can be viewed as a non-interfered packet (if it has roughly the same variance as the estimated unknown variance of the AWGN) that must be conserved, or considered as an interference packet (if its variance is significantly greater than the variance of the AWGN) that should be thresholded. The conservation (or inversely the thresholding) of a packet is achieved by the use of DONOHO's Universal-Threshold apart from that the variance is estimated based on the statistical sampling theory. The Final step consists in the application of the inverse DCT to obtain a good approximation of the received interference-less signal. The results obtained from several simulations confirm that the suggested strategy outperforms, in term of signal quality restoration, the conventional methods.

Purpose -The purpose of this work is to propose a new multi-user detector which cascades the linear G-SIC with some linear PIC stages to form a new linear hybrid multi-user detector. Design/methodology/approach -Multistage interference cancellation multi-user detectors became an increasingly important area of research due to their relative low computational complexity. The performance comparison of the proposed linear HIC is studied and presented using matlab environment to investigate the bit error rates. For DS/CDMA system, each user is characterized by its own code. The signals from users are spread by appropriately design sequences and then transmitted over an AWGN channel with BPSK modulation. Findings -By the cascade of the linear G-SIC and the traditional PIC, a low complexity multi-user detector is found capable of reducing the long detection delay compared with the linear G-SIC. The advantages of the linear G-SIC and PIC can be exploited substantially. Originality/value -The paper proposes an algorithm that can combat the MAI with less complexity, and also can speed the convergence compared with other detectors.