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: Computer science & Control theory. The organization has 1138 authors who have published 1381 publications receiving 7798 citations.

Reliability, Availability and Maintainability Analysis for Transportation Vehicles—A Case Study in APSRTC

Abstract: Performance of a system depends on the reliability of its subsystems if any, the maintenance efficiency, and the operating conditions. Failures are more frequent if the size and complexity of the systems increase and the effect of these failures on system performance is critical. Therefore, reliability and maintainability analysis is required to identify the bottlenecks in system for designed reliability and maintainability. In this paper, a methodology has been presented and is applied on road transportation vehicles in Andhra Pradesh State Road Transport Corporation (APSRTC) as a case study. The best fit for time between failures (TBF) of subsystems is identified with Anderson–Darling (A–D) values and the respective parameters are calculated. Also, availabilities are estimated for all types of vehicles and bottlenecks are identified. This method will help to identify the optimal maintenance intervals for each subsystem as well as the system.

Augmentation of sensitivity of FBG sensor using microwave photonics and nonlinear effect

Abstract: A simple and unique scheme of high sensitive Fiber Bragg Grating(FBG) interrogation system based on microwave signal measurement utilizing the concept of microwave photonics and nonlinear Four wave mixing(FWM), is proposed. The concept of FWM process is combined with microwave photonics to enhance the sensitivity of FBG sensor. The strain induced wavelength shift of the sensing FBG is translated to higher wavelength shift of the corresponding higher order FWM signals on either side of FBG sensor wavelength in opposite directions. Thus the wavelength separation between the FWM signals increases with small increase in strain. Utilizing the FWM effect and microwave photonics technique, the microwave phase difference is altered, which ultimately is converted to significant change in RF intensity. A novel mathematical relationship relating FWM, applied strain and the microwave power of the proposed scheme is established. A high strain sensitivity of 36.52 μV/με (26.67 μW/με) is attained using the proposed FWM and microwave photonics technique against initial sensitivity of 4.9 μV/με (0.48 μW/με) using only microwave photonics technique. The proposed scheme automatically compensates the temperature variations and eliminates the requirement of high dispersive component to enhance the sensitivity.

Design of Frequency Domain Induced Polarization Equipment having Optimized Frequency of Signal Transmission

Abstract: Soil resistivity is measured by resistivity or induced polarization methods. In induced polarization techniques, time domain or frequency domain methods are used. The frequency range of operation is 1-10 Hz. In this paper we have designed a frequency domain induced polarization equipment for 55 v/110 V/220 v range in dc and ac. Frequency selection is done as some cardinal parts 0.1, 1.0, 0.3 and 3.0… up to 10 Hz. The collected data for each of the frequency is used to compute the percentage of frequency effect. The values are to be obtained in different kinds of soil for optimization of frequency. This instrument has wide application in demarcating types of soil/rock for pollution and disaster management studies.

Vivaldi Antenna design for short range and high data rate communications

Abstract: The demand for faster access and transfer of the high quality data is ever growing. This probes for higher data rates in communication networks. To meet this demand, we need devices which operate at such high data rates. Most of the networks Off-late being wireless, antennas used in such networks should be able to operate over a wide band width. Vivaldi antenna is one such structure which has wide band width and end fire radiation pattern. So a Vivaldi antenna design which can operate at such high data rates for short range communications is proposed in this paper. Because it operates at low power and has directive radiation pattern, interference can easily be avoided during the data transfer.