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.

Assessment of algal biomass towards removal of Cr(VI) from tannery effluent: a sustainable approach.

Abstract: The current investigation focuses on a systematic study of application of two dried algal biomass (i.e., Nostoc sp. and Turbinaria vulgaris) in removal of Cr(VI) from synthetic solution as well as tannery industrial wastewater. The optimized conditions for Cr(VI) removal are nearly same for the both the biosorbents (i.e., pH 2.8, initial Cr(VI) concentration 100 mg L−1, biomass dosage of 1.2g L−1, contact time 120 and 110 min). Nostoc sp. (qmax=23.94mg g−1) was observed to possess a superior removal capability when compared to Turbinaria vulgaris (qmax=21.8mg g−1). Desorption studies were performed with four different desorbing agents. Application study was conducted using tannery wastewater with Nostoc sp. and 94.20% removal of Cr(VI) was obtained. Hence, this study revealed that Nostoc sp. and T. vulgaris both have great potential to be an environment friendly and economic biosorbent for removal of Cr(VI) containing industrial effluent.

Thermal, mechanical and optical studies of copper ion-doped glass material for the band pass filter

Abstract: Copper ion-doped glass material is prepared by melt quenching technique. A significant increase has been observed in the values of density and refractive index of this non-crystalline material with the increase in concentration levels of copper in the glass composition. Thermal properties of present glasses have been evaluated and Hruby’s criterion value KH = 0.4051 reveals exceptional stability of this glass material. Mechanical properties like coefficient of friction, specific wear rate, specific wear energy and Vicker’s micro-hardness of the present glasses have been investigated. Optical absorption occurred in ultraviolet, visible and near infra-red regions. The optical direct bandgap decreased from 2.94 to 2.93 eV and the indirect bandgap decreased from 2.92 to 2.89 eV with the uniform increase in the copper ion concentration, and revealed semiconductor nature of the material which is useful for protecting the solar cell. The transmission studies unravel the utility of the material as band pass filter in UV region at 366.21, 378.63 and 385.16 nm and having full-wave half-maximum (FWHM) 5.46, 3.74, and 13.74 nm and in the visible region at 415.49 nm with a full-width half-maximum width (FWHM) 2.56 nm.

A Cost Effective Desalination Plant Using a Solar Chimney with Recycled Aluminum Can Collector

Abstract: The main objective of the work was to use solar energy for desalination of water. A solar chimney desalination system, which includes the solar chimney, solar collector, evaporation system, and passive condenser, was designed and built. The air enters into collector and gets heated and released at the bottom of chimney. Due to draught effect dry air goes upward. The air is humidified by spraying salt water into the hot air stream using a mistifier at the middle of chimney. Then, the partial vapours contained in the air are condensed to give desalinated water. The performance of the integrated system including power and potable water production was estimated and the results were discussed. With a 3.4 m height setup, experimental test rig was capable of evaporating 3.77 L water daily condensing 2.3 L water. It is compact in nature as it is easy to assemble and dissemble. It can be used for purifying rain water in summer under rain water harvesting. Because of using country wood, recycled Al cans, and GI sheet in fabrication, it is lower in cost.

An efficient text dependent speaker recognition using fusion of MFCC and SBC

Abstract: In this paper an efficient approach for the recognition of a speaker based on text dependent speech is presented. Speaker Recognition/ Verification system suffers with wide variety of problems. In the proposed approach, the features are extracted using two methods such as Mel Frequency Cepstral Coefficients and wavelet subband coefficients, and then these futures are fused through concatenation to give optimum performance. Those concatenated feature set are more reliable to discriminate an imposter from the genuine. Those concatenated features are classified using support vector machine classifier. Performance of the proposed approach is validated on a self generated corpus of size 300 samples of 20 individual. The proposed method outperforms other existing methods.

Soft switching boost converter for DC input LED drivers

Abstract: LED lighting has attained maximum acceptance in the recent past for indoor, outdoor and special purpose applications. In most of the battery driven / PV based applications, efficient constant current driving of LED arrays is essential. Therefore, adopting soft switching for the power switch is important to achieve greater efficiency at higher frequencies, simultaneously realizing better power densities. In this paper, a technique is proposed which results in the complete soft switching of the power switch without any auxiliary switch and /or elaborate control mechanisms. Only an additional transformer is introduced to recycle the switching power to the output load. The concept is validated by building a 100W LED driver with 24 VDC input and 135 VDC output operating at 110 KHz. About 6 percent improvement in the efficiency was achieved with this technique.