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.

Telephony Speech Enhancement for Elderly People

Abstract: One of the limiting factors of performance of any communication system is bandwidth. In telephone systems, the operational voice frequency ranges from 300 to 3400 Hz and is called Narrow Band (NB). This NB causes remarkable depreciation of speech in terms of quality and intelligibility, specifically for elderly persons. Speech Bandwidth Extension (SBE) technique is used to increase the quality and intelligibility of NB signal. In SBE method, additional data about the lost speech frequency components is transmitted along with NB signal. A better-quality Wide Band (WB) signal is reconstructed at the receiver end using the transmitted missing speech frequency components. This paper explores the ability of SBE to enhance the quality and intelligibility of NB signal for elderly persons. The enhancement in the quality and intelligibility of NB speech for elderly persons is reasserted by subjective listening and objective tests.

Performance Improvement in Vector Control of Induction Motor Drive Using Fuzzy Logic Controller

Abstract: This paper presents an intelligent speed control system based on fuzzy logic for a voltage source PWM inverter-fed indirect vector controlled induction motor drive. Traditional indirect vector control system of induction motor introduces conventional PI regulator in outer speed loop; it is proved that the low precision of the speed regulator debases the performance of the whole system. To overcome this problem, replacement of PI controller by an intelligent controller based on fuzzy set theory is proposed. The performance of the intelligent controller has been investigated through digital simulation using MATLAB-SIMULINK package for different operating conditions such as sudden change in reference speed and load torque. The simulation results demonstrate that the performance of the proposed controller is better than that of the conventional PI controller.

A Three Component Protocol for the Synthesis of Aziridines using BF3·(OEt)2

Abstract: Synthesis of N-(1R,2S)-2-(bromo-3-oxo-1,3-diphenylpropyl)-4-methylbenzene sulfonamide and N-(1R,2S)-(2-bromo-3-oxo-1,3-diphenylpropyl)-4-methylbenzene sulfonamide was carried out by a three component reaction using phenacyl bromide, p-toluenesulfonamide and carboxyaldehyde in presence of mild Lewis acid such as BF3·(OEt)2 in dichloromethane. The synthetic utility of this protocol was carried out with syn-isomer to yield corresponding cis-aziridines. This protocol was operationally simple for a wide variety of substituted carboxaldehydes and substituted phenacyl bromides.

A Comparative Analysis of Fractional Filter PID Controller for Integrating Processes with Time Delay

Abstract: This article deals with the performance and fragility analysis of fractional filter PID controller designed for several integrating time-delay processes. The controller performance is assessed with the variation of fractional IMC filter time constant as it greatly affects the closed-loop performance. This is achieved with the help of different performance measures. Further, the fragility analysis is accomplished for variation in the controller parameters to assess the robustness and performance of the controller. This is executed for variation in individual controller parameters. Later, the controller parameter which is affecting the robustness and performance of the controller is presented. Three examples representing three different integrating processes are considered for illustrating the performance and fragility analysis of the controller.