Faculty Publications
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Item Design and simulation of high pressure piezohydraulic pump with active valves(Institute of Electrical and Electronics Engineers Inc., 2016) Rao, S.N.; Rao, R.Pumps incorporated with active valves provide active control on both the inlet and outlet valves. Here piezoelectric actuation is used as the actuation system since piezoelectric actuators can produce controlled actuation. Also piezoelectric actuators can produce high displacement with large force and has advantages such as high resolution, fast response, high stability, high reliability, compactness etc. In this work active valves are designed for a high pressure piezo-hydraulic pump. Flexural amplifiers for piezoelectric actuators are designed for the valve diaphragm actuation as well as for the pumping diaphragm actuation. There are three slotted diaphragms designed and operated by three separate flexurally amplified piezoelectric actuators. The flexural amplifiers and the diaphragms are analysed using ANSYS analysis software. Suitable mathematical model is developed using MATLAB software for synchronizing the sequence of actuation with respect to timing. Here Bouc-Wen model is made use for modelling the hysteresis effect. MATLAB Simulink is used to develop the model and simulations are performed to determine the displacement produced by the piezoelectric actuators when applied with a voltage. Also simulations are carried out for the determination of pumped volume, flow rate and stroke length of a particular cylinder. © 2016 IEEE.Item High throughput and high capacity asynchronous pipeline using hybrid logic(Institute of Electrical and Electronics Engineers Inc., 2017) Girija Sravani, K.; Rao, R.This paper proposes a novel high throughput and high capacity asynchronous pipeline architecture, named High capacity Hybrid logic pipeline. The proposed pipeline architecture is intended for the data paths that use domino logic. This pipeline structure, combines the merits of hybrid logic encoding scheme(robustness and simplicity) and High capacity single-rail protocol (high throughput and full buffering capacity). The validity of the proposed pipeline structure has been tested by simulating a 4-bit, 10-stage FIFO in 180 nm technology. The FIFO has exhibited a throughput of 2.23 giga-items/s and this number is 23.2% higher than one of the best existing pipeline (High capacity single-rail). © 2017 IEEE.Item Influence of modified cutting inserts in machining of Ti-6Al-4V alloy using PCD insert(Elsevier Ltd, 2018) Rao, R.; Rao, S.S.; Herbert, M.A.In modern manufacturing industries, the emerging needs of modern metal cutting operation are to increase the tool life with good surface finish and higher material removal rate. These objectives can be achieved by reducing the cutting temperature at the cutting zones with proper cooling system. The present work involves the experimental study of MQL application through the micro-holes drilled on the cutting inserts during turning of Ti-6Al-4V alloy using PCD inserts. The effect of the micropool lubrication of cutting insert on cutting temperature, surface roughness and tool wear have been compared with normal insert machining. It has been observed that in micropool lubrication method, cutting temperature was reduced by 30-33% over normal insert machining. Micropool lubrication reduced the flank wear to a maximum of about 20-30% over normal insert machining. The experimental result of the current research work indicates considerable benefits of surface roughness and tool wear through reduction in cutting temperature due to the perforation of the cutting insert. © 2018 Elsevier Ltd. All rights reserved.Item Performance improvement studies for cutting tools with perforated surface in turning of titanium alloy(EDP Sciences edps@edpsciences.com, 2018) Rao, R.; Shrikantha, R.; Mervin, H.In turning process, the cutting tool is essential for shaping materials. The cutting tools with various perforated surfaces help to increase the cutting tool life. Also, advances in CNC machining technologies have enhanced the productivity of machining process. One of the best or futuristic approaches in modern manufacturing engineering is the use of FEM Simulation for the metal cutting process. FEM simulation helps in understanding the metal deformation process and also helps in the reduction of experiments. The simulation helps the researchers to predict the major influencing cutting variable values without carrying out any experiment which is time-consuming and expensive. This research presents the simulation study of the performance of micro-hole patterned Polycrystalline Diamond cutting insert in machining Titanium alloy (Ti-6Al-4V). Micro-holes are drilled using Electrical Discharge Wire Drilling machine on the rake face of Polycrystalline Diamond (PCD) cutting inserts. FEM analysis is carried out to evaluate the effect of perforations on the mechanical integrity of insert. The micro-hole patterned insert is modeled in PRO-E modeler and simulated using DEFORM-3D software. The effective stress, strain, and temperature distribution are analyzed and the results are compared with the normal insert. © The Authors, published by EDP Sciences, 2018.Item Investigations on the Effect of Spacer Dielectrics on the DC Characteristics of Dual Material Gate Junctionless FinFETs(Institute of Electrical and Electronics Engineers Inc., 2020) Mathew, S.; Nithin, N.; Rao, R.This work analyses the influence of dielectric constant of spacer on the electrical characteristics as well as on two vital short channel effect parameters i.e DIBL and Subthreshold Swing of Dual Material Gate Junctionless FinFET (DMG-JLFinFET). Various spacer materials each with different dielectric constant, were used for 3D TCAD simulations. It was observed that high κ spacers gave higher value of ON current. Increase in leakage current was also observed for high κ spacers at higher negative gate bias. Subthreshold Swing (SS) as well as Drain Induced Barrier Lowering (DIBL) had reduced extensively with the increase in dielectric constant of spacer. © 2020 IEEE.Item Impact of the diaphragm structure on the linearity and temperature sensitivity of low-pressure piezo-resistive MEMS pressure sensors(Institute of Physics Publishing helen.craven@iop.org, 2020) Nithin, N.; Rao, R.; Bhat, K.N.This paper presents result of a detailed simulation study aimed at optimizing the different diaphragm structures of silicon micro machined MEMS pressure sensor for operation and measurement of the low-pressure ranges(600mbar). We first show that the conventional arrangement of the Wheatstone bridge resistors realized using the "Flat diaphragms" give rise to large temperature dependence of the offset voltage which affects the sensitivity and linearity of the pressure sensors during operation in the temperatures ranging from-40Cto+80C, thus making the temperature compensation of the sensor output voltage rather tedious and impossible in certain instances. We further demonstrate that, this issue can be circumvented and excellent linearity with minimum dependence of the offset-voltage, sensitivity and linearity can be achieved by using "sculptured diaphragms" with optimized diaphragm dimensions. Towards this goal, in this paper, we present a set of simulation studies involving optimization of the pressure sensor diaphragm dimensions and structures with single and multiple boss structures to achieve better sensitivity, linearity, and at the same time minimize temperature drift, and to achieve better repeatability. © Published under licence by IOP Publishing Ltd.Item Simulation and Modelling of screen oxide thickness dependent implantation peak position in Silicon(Institute of Electrical and Electronics Engineers Inc., 2020) Hegde, G.R.; Nikhil, K.S.; Rao, R.The relation between peak boron concentration position from the silicon-silicon dioxide interface (xp) after implantation through screen oxide with oxide thickness of (tox) is investigated in this paper. It is observed that the xp decreases with increase in tox. The rate of reduction is observed to be significantly higher for thin oxides. An empirical relation is proposed to model the oxide thickness dependent peak position with appropriate model parameters. © 2020 IEEE.Item Investigations on the effect of Dual Material Gate work function on DIBL and Subthreshold Swing in Junctionless FinFETs(Institute of Electrical and Electronics Engineers Inc., 2020) Mathew, S.; Nithin; Bhat, K.N.; Rao, R.This paper investigates the influence of gate material work function on the electrical characteristics as well as short channel effects exhibited by Dual Material Gate-Junctionless FinFETs (DMG-JLFinFETs) with channel length as low as 10 nm. 3D TCAD simulations performed on these devices show that various device parameters like threshold voltage, ON-current, etc, are influenced by the work function difference between the control gate and screen gate material of DMG-JLFinFET. DMG-JLFinFETs exhibit very low Drain Induced Barrier Lowering (DIBL), far lesser than its Single Material Gate (SMG) counterpart. Subthreshold Swing (SS) of DMG devices is higher than SMG devices. The optimal ratio of control gate length to total gate length in DMG-JLFinFET is found to be between 0.5 and 1 for better suppression of short channel effects. © 2020 IEEE.Item Experimental investigations of structurally pre-stressed actuator based active vibration isolation system(American Institute of Physics Inc. subs@aip.org, 2020) Divijesh, P.; Rao, M.; Rao, R.; Dheeraj; SushithActive Vibration Isolation is considered to be one of the most effective methods to reduce the undesirable vibrations generated in any mechanical system. Stacked piezoactuators are suitable actuators used for variety of applications such as micro and nano positioning applications because of their high stiffness and fast response. However in order to provide optimal preloading force to the stacked actuators for longer lifetime and better performance with dynamic applications these stack actuators are structurally pre-stressed. In the present work, an active vibration isolation system is designed and developed using two structurally pre-stressed actuators namely source actuator and isolator actuator where source actuator is used for generating vibrations and the isolator actuator to nullify the generated vibrations. Initially the transfer function of the MLA 10x10x20 stack actuator was identified using its known parameters and was modeled in MATLAB/ Simulink to estimate the simulated displacement for a particular voltage at different frequencies. The simulated displacements were then compared with experimental displacements for different frequencies and the results were plotted. The experimental displacements of both source actuator and isolator actuator were found at different frequencies and was compared with the simulated displacements for a particular voltage and the results were plotted. Finally active vibration isolation experiments were carried out using the proposed set up for a particular voltage at different frequencies and the percentage of vibration isolation achieved was also estimated. © 2020 Author(s).Item DDCVS Logic for Asynchronous Gate-Level Pipelined Circuits(Springer Science and Business Media Deutschland GmbH, 2021) Girija Sravani, K.; Rao, R.This paper proposes a new way of realizing the data paths for asynchronous domino logic gate-level pipeline styles. This novel approach improves the speed of the pipelines by preserving the latch-less feature of domino pipelines. In this work, the data paths of three asynchronous 16-bit adders based on APCDP, LP2/2, and HC-Hybrid pipelines are constructed using dual-rail domino cascode voltage switch (DDCVS) logic and simulated using cadence toolset in 90 nm technology. The adders based on DDCVS logic have exhibited higher performance and lower energy-delay square product compared to the adders based on domino logic. © 2021, Springer Nature Singapore Pte Ltd.