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.

Three Phase Multi-Level Inverter Topologies and Modulation Techniques: A Short review

Abstract: In this paper recently proposed three-phase multi-level inverter topologies and modulation techniques are discussed. Multilevel inverter topologies (MLIs) are more utilized in high-medium power applications due to their several benefits such as less harmonic contents, less power dissipation on power switches and less electromagnetic interference (EMI) outputs. For harmonic elimination, the chosen switching method for inverter control is also a plays a significant role to produce the ideal output voltage. In this, mainly three different topologies are categorized in MLIs; those are diode clamped, flying capacitors and cascaded H-Bridge. Similarly, different H-Bridge inverter topologies and control techniques also discoursed. In this paper mainly focused on three-phase inverter using a single DC source and transformers. The various carrier based modulation techniques such as phase disposition (PD), Phase Opposite Dispostion (POD) and Alternate Phase Opposite Dispostion (APOD) have been invstigated through MATLAB/Simulink environments.

Unsaturated Polyester—Macrocomposites

Abstract: Unsaturated polyester resins are among the most significant and industrially versatile thermosetting materials and are used in a wide range of applications, including automotive, marine, transport, building, construction, aerospace, and electronic devices due to their low cost, ease of fabrication, and high-performance properties. In order to improve their mechanical strength and tribological behavior, they are normally reinforced with various types of reinforcements ranging from nano to macro size. The present chapter provides an overview of the preparation, characterization, and classification of unsaturated polyester macrocomposites, including their properties and applications.

An Area Efficient Built-In Redundancy Analysis for Embedded Memory with Selectable 1-D Redundancy

Abstract: In this paper, a novel redundant mechanism for dual port embedded SRAM is presented. This work relates to 1-D (one dimensional) bit oriented redundancy algorithm to increase the reliability and yield during manufacture of memory integrated circuit chips, specifically to the efficient use of the limited space available for fuse-activated redundant circuitry on such chips, and more particularly, to replace multiple faulty memory locations using one independent redundancy element per sub-array, and reducing the number of defects-signaling fuses. In this way we double the yield and repair rate with 0.5% area penalty.

Ionic liquid-based vortex-assisted DLLME followed by RP-LC-PDA method for bioassay of daclatasvir in rat serum: application to pharmacokinetics

Abstract: Daclatasvir is a direct-acting antiviral agent against hepatitis C virus (HCV) used for the treatment of chronic HCV genotype infections of 1 and 3. Hepatitis C is an infectious liver disease caused by infection with hepatitis C virus (HCV). There are no reports found to be daclatasvir in ionic liquid-based extraction. A simple vortex assisted an environmental eco-friendly ionic liquid dispersive liquid–liquid microextraction method for determination of daclatasvir form rat serum. For the sample extraction, various green solvents, like ionic liquids, were used. The repercussion of various dispersive solvents, extractant, and disperser ratios was evaluated; non-identical ionic liquids assess the salt concentration on sample recoveries and enrichment factors were examined. Amid all the ionic liquids that were scrutinized, 1-butyl-3-methylimidazolium hexafluorophosphate was selected as the most effective ionic liquid. The present bioassay recoveries were found to be more than 99.4% at an extractant and disperser ratio of 0.43 with an addition of 5.0% NaCl (sodium chloride) that was selected as an effective salt concentration for present extraction. Compared to protein precipitation, the enhanced detection and quantification limits attained were 0.015 μg/mL and 0.045 μg/mL, respectively. A linear relationship in the range of 0.05–10.0 μg/mL respectively with a correlation coefficient of (r2) 0.9996 was observed. The developed method was successfully applied to study the pharmacokinetics of daclatasvir in rat serum according to the bioanalytical method validation guidelines.

Evaluation of welding characteristics using three-dimensional finite element simulation and experimentation for FSW of aluminum 6061

Abstract: Aim of this study is to introduce numerical 3D finite element method (FEM) simulation to study characteristics of friction stir welding. A coupled experimental and numerical simulation study was carried out to study the effect of process parameters on welding characteristics for friction stir welding of aluminium 6061. As per Box–Behnken design, 15 experiments have been conducted on aluminium 6061 plates at three levels of spindle speed, tilt angle and tool pin diameter. Experimental results of tool vibration, force in X, Y and Z directions and ultimate tensile strength were collected and analyzed. Shearing of metal and metal flow patterns during the welding were analyzed and the responses were predicted using FEM simulation. Size of the shear zone around the tool pin was studied for different combinations of the parameters. The experimental results and the FEM-simulated values were found to be in good agreement. Interaction effect of the process parameters on the responses was analyzed using response surface methodology.