Vignan University

About: Vignan University is a education organization based out in Guntur, Andhra Pradesh, India. It is known for research contribution in the topics: Control theory & CMOS. The organization has 1138 authors who have published 1381 publications receiving 7798 citations.

Simulation and analysis of three-phase parallel inverter using multicarrier PWM control schemes

Abstract: Simulation and analysis of three-phase parallel inverter using multicarrier pulse width modulation such as phase disposition (PD), phase opposition disposition (POD) and alternate phase alternate disposition (APOD) are presented in this article. In this proposed work, reduced active switching count, transformers, single DC input, a high degree of modularity and redundancy are key merits and also suitable for renewable energy systems. The proposed three-phase five-level multilevel inverter with single DC source using a three-phase transformer is controlled by multicarrier pulse width modulation schemes. To generate switching pulses for five-level inverter, four carrier signals can be compared with a reference signal. The performance of the inverter is examined by using PD, POD, and APOD by modulation index (MI) starting from 0.4 to 1. Furthermore, the over-modulation region is also analyzed in this paper. The effectiveness of the system is analyzed in terms of total harmonic distortion by varying the MI of the inverter. The simulation results are verified through MATLAB/Simulink.

Performance analysis for the Feature Extraction algorithm of an ECG signal

Abstract: An Electrocardiogram is a significant recording for measuring the electrical activity of the heart. The Feature Extraction of an ECG signal plays a significant role in diagnosing most of the cardiac diseases. This paper concentrates on the algorithm for extraction of the fiducial points of an ECG signal and its performance analysis. To analyze these signals, time-frequency domain is the best suited method. In order to analyze these physiological and non-stationary signals, a Wavelet Transform in which Discrete Wavelet Transform is preferred to Fast Fourier and Short time - Fourier transform. A Discrete Wavelet Transform (DWT) is employed for the better understanding of the ECG signal in Time -Frequency plane with (Haar) as a Mother Wavelet function. The Samples are taken from the available ECG databases PTBDB & QTDB and are checked against the CSE tolerance limits. Since, real time signals like ECG can be easily processed using a DSP processor, the algorithm is targeted onto a ADSP - 2181 to reduce the complexity of the code and obtain optimized power levels.

Thermal Slip Flow of a Three-Dimensional Casson Fluid Embedded in a Porous Medium with Internal Heat Generation

Abstract: Present assessment is considered to analysis flow as well as heat characteristics of steady, thermal slip flow of three-dimensional Casson fluid embedded in a porous medium with internal heat generation. Geometry of the present analysis is linearly stretched surface. Later, all the PDEs corresponding to the study are altered to set of nonlinear equations ODEs by means of appropriate similarity transformations. An efficient numerical scheme of spectral relaxation method (SRM) is applied to solve the nonlinear ordinary system. Variations of Nusselt number, temperature, velocity, and local skin friction coefficient with fluid parameters exhibited by graphs and tables. Spectral relaxation method gives an exact convergence to the nonlinear boundary value problems compare with general methods. In this study, to improve the precision and accuracy of the SRM successive over-relaxation (SOR) strategy is utilized. Proposed method as well as outcomes is checked with the comparison. A sensible connection is acquired between the current outcomes and accessible outcomes in writing. Some of the observations are skin friction coefficient raises and velocities decreases by the magnetic field strength. Skin friction and Local Nusselt number at the surface is more pronounced for non-Newtonian case than that of Newtonian case.

Performance Evaluation of Population Seeding Techniques of Permutation-Coded GA Traveling Salesman Problems Based Assessment: Performance Evaluation of Population Seeding Techniques of Permutation-Coded GA

Abstract: Genetic algorithms (GAs) are a population-based meta-heuristic global optimization technique for dealing with complex problems with a very large search space. The population initialization is a crucial task in GAs because it plays a vital role in the convergence speed, problem search space exploration, and also the quality of the final optimal solution. Though the importance of deciding problem-specific population initialization in GA is widely recognized, it is hardly addressed in the literature. In this article, different population seeding techniques for permutation-coded genetic algorithms such as random, nearest neighbor (NN), gene bank (GB), sorted population (SP), and selective initialization (SI), along with three newly proposed ordered-distance-vector-based initialization techniques have been extensively studied. The ability of each population seeding technique has been examined in terms of a set of performance criteria, such as computation time, convergence rate, error rate, average convergence, convergence diversity, nearest-neighbor ratio, average distinct solutions and distribution of individuals. One of the famous combinatorial hard problems of the traveling salesman problem (TSP) is being chosen as the testbed and the experiments are performed on large-sized benchmark TSP instances obtained from standard TSPLIB. The scope of the experiments in this article is limited to the initialization phase of the GA and this restricted scope helps to assess the performance of the population seeding techniques in their intended phase alone. The experimentation analyses are carried out using statistical tools to claim the unique performance characteristic of each population seeding techniques and best performing techniques are identified based on the assessment criteria defined and the nature of the application.