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.

Co-substitution of Er/Yb on structural and electrical properties of NKBT–BCZT solid solutions

Abstract: Single-phase Er/Yb co-substituted 0.94(Na0.4K0.1Bi0.5−x–yErxYbyTiO3)–0.06(Ba0.85Ca0.15Zr0.1Ti0.9O3) $$(x = 0.01, \;y = 0.02\;{\text{and}}\; x = 0.02,\; y = 0.01)$$ (NKBT–BCZT) lead-free ceramics were synthesized by conventional solid-state reaction. The structural properties of the ceramics were confirmed with the help of X-ray diffraction studies. The crystal structure of NKBT–BCZT changed from rhombohedral to a morphotropic phase boundary and then to tetragonal phase in the presence of BCZT. The surface morphology of these ceramics was well packed with high-density and delineated grain boundaries which were confirmed with the help of the density of the samples. It was noted that the grain sizes decreased slightly by altering the Er/Yb compositions. The temperature dependence dielectric study revealed the existence of ferroelectric and antiferroelectric phase transformations in two independent regions. The temperature dependence conductivity study showed doubly ionized oxygen vacancies due to the presence of a defect dipole, which helps to promote ionic conductivity at a high temperature region. The observed room temperature P–E loops were identified from well-saturated slim loops having reduced coercivity which was found to be useful for potential applications in the field of energy storage devices.

Multi level statistical optimization of l -asparaginase from Bacillus subtilis VUVD001

Abstract: Physical and chemical factors influencing the anti-leukemic l-asparaginase enzyme production by Bacillus subtilis VUVD001 were optimized using multi-stage optimization on the basis of preliminary experimental outcomes obtained by conventional one-factor-at-a-time approach using shake flasks. Process variables namely carbon, nitrogen sources, pH and temperature were taken into consideration during response surface methodology (RSM) optimization. The finest enzyme activity of 0.51 IUml−1 obtained by OFAT method was enhanced by 3.2 folds using RSM optimization. Artificial neural network (ANN) modelling and genetic algorithm (GA) based optimizations were further carried out to improve the enzyme drug yield. Results were also validated by conducting experiments at optimum conditions determined by RSM and GA optimization methods. The novel bacterium yielded in 2.88 IUml−1 of enzyme activity at optimum process variables determined by GA optimization, i.e., 0.5% glucose, 8.0% beef extract, 8.3 pH and 49.9 °C temperature. The study explored the optimized culture conditions for better yielding of anti-leukemic enzyme drug from a new bacterial source namely Bacillus subtilis VUVD001.

Palmprint identification and verification based on wide principal lines through dynamic ROI

Abstract: In this paper, a novel palmprint identification and verification algorithm is proposed based on wide principal lines through dynamic ROI. Region of interest ROI extraction is an important task for palmprint identification. Earlier reported works used fixed size ROI for the recognition of palmprints. When the fixed size ROI is used the palm area taken up for recognition is less compared to dynamic ROI extraction. The proposed algorithm focuses on extraction of maximum possible ROI. A set of wide principal line extractors are devised. Later these wide principal line extractors are used to extract the wide principal lines from dynamic ROI. A two stage palmprint identification algorithm is proposed based on wide principal lines. The experimental results demonstrate that the proposed approach extracts better ROI on the PolyUPalmprint Database when compared to the existing fixed size and dynamic size ROI extraction techniques. The experimental results for the verification and identification on PolyUPalmprint Database show that the discrimination of wide principal lines is also strong.

Wideband Circular Polarized Binomial Antenna Array for L-Band Radar

Abstract: This paper presents a compact binomial rectangular patch antenna array with wide bandwidth and circular polarization for the L-band radar application operating at the frequency of 1.35 GHz. A 16-element planar antenna array is designed with independent coaxial feed to each element which helps in reduction of negative effects of complex feed network on antenna performance. The patch elements are truncated diagonally which is useful in producing circular polarization. There is an air cavity in between the ground plane and substrate which helps in improving the gain of the antenna and the cumulative effect of the truncated patches and the air cavity will increase the bandwidth of the antenna. The inter-element spacing in the antenna array is considered as half of the free space wavelength. The antenna elements are fed with nonuniform amplitudes to reduce the side lobe levels which are a major problem in radar applications for this Pascal triangle coefficient are considered for feeding the antenna elements.