this paper proposes the application of Discrete Wavelet Transform (DWT) to detect the QRS (ECG is characterized by a recurrent wave sequence of P, QRS and T-wave) of an electrocardiogram (ECG) signal. Wavelet Transform provides localization in both time and frequency. In preprocessing stage, DWT is used to remove the baseline wander in the ECG signal. The performance of the algorithm of QRS detection is evaluated against the standard MIT BIH (Massachusetts Institute of Technology, Beth Israel Hospital) Arrhythmia database. The average QRS complexes detection rate of 98.1 % is achieved.
<p>In this paper, a novel approach to nonlinear control of induction machine, recursive on-line estimation of rotor time constant and load torque are developed. The proposed strategy combines Integrated Backstepping and Indirect Field Oriented Controls. The proposed approach is used to design controllers for the rotor flux and speed, estimate the values of rotor time constant and load torque and track their changes on-line. An open loop estimator is used to estimate the rotor flux. Simulation results are presented which demonstrate the effectiveness of the control technique and on-line estimation.</p>
This paper focuses on the problem of controlling a single phase DC-AC switched power converter used in Uninterruptible Power Supply (UPS). The control objective is to generate, at the system output, a sinusoidal voltage with amplitude and frequency fixed by the reference signal. To this end, three types of regulators are designed based on Backstepping technique, Sliding Mode approach and linear PID controller. A comparative study of performances of designed controllers is made by simulations in Matlab/Simulink environment.
The main contribution of this work is to propose an efficient and accurate method for identifying and determining the values of equivalent circuit elements of photovoltaic module using only exact analytical equations and four manufacture's data reference, i.e., the open-circuit voltage (VOC) , the short-circuit current (ISC) and the current and the voltage at the maximum power point (IM , VM). All used equations were obtained with a transparent analytical procedure. To avoid using any mathematical simplifications or other physical assumptions when extracting RS (series resistance) parameter, a fast and accurate iterative numerical method is proposed. For determine a four or five PV parameters model, many authors proposed several procedures that require the entire experimental I-V curves or based on many estimations, assumptions and simplifications for solving non-linear I-V equations. These techniques lead to a PV parameters model with a minimum error. We apply this combined method in order to extract the four-parameter Single-Diode models of photovoltaic modules. The effectiveness of this approach is evaluated and validated by Matlab/Simulink environment, through comparison of simulation results of the model to the data provided by product's manufacturer. It envisaged that this work is very useful for PV power electronics designers who require exact, fast and accurate approach for modeling emulating their photovoltaic modules under various environmental conditions.
In this paper, a multiband and miniature rectangular microstrip antenna is designed and analyzed for Radio Frequency Identification (RFID) reader applications. The miniaturization is achieved using fractal technique and the physical parameters of the structure as well as its ground plane are optimized using CST Microwave Studio. The total area of the final structure is 71.6 x 94 mm<sup>2</sup>. The results show that the proposed antenna has good matching input impedance with a stable radiation pattern at 915 MHz, 2.45 GHz, and 5.8 GHz.
This paper presents a robust control strategy for a grid connected photovoltaic system with a boost converter by using an integral Backstepping method based on a nonlinear state model, which guarantees the Lyapunov stability of the global system. The system has tracked precisely the maximum power point, with a very fast response and the unit power factor has been observed under different atmospheric conditions. Moreover, the best advantage of the controller is that it’s a good corrector of the grid perturbation and system parameter disturbance. The simulation result has demonstrated the performance of this strategy.
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