Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item Modeling and experimental validation of valve and pumping actuator of a piezo-hydraulic pump(Zibeline International Publishing Sdn. Bhd., 2019) Nayak, S.; Rao, M.; Rao, R.This paper presents experimental investigations on valve actuator and pumping actuator of a piezo-hydraulic pump with active valves. Quadratic arm flexurally amplified piezoelectric actuators (QAFAPA) are designed for the pumping actuator and the valve actuator. Simulations are carried out to determine the voltage-displacement characteristics of the QAFAPA using MATLAB/Simulink software. To perform the pumping action, slotted pumping diaphragm is designed considering acrylic as the material and is analyzed for its stiffness using ANSYS analysis software. The slotted pumping diaphragm is fabricated, and the stiffness is experimentally determined which matched well with the analysis result. One pumping actuator and one actuator similar for inlet and outlet valve is developed. Voltage-displacement experiments are carried out on the valve actuator and the pumping actuator. Further, the displacement of the slotted pumping diaphragm when assembled with pumping actuator is experimentally determined. Simulation and experimental results were compared, and the results obtained were in good agreement with each other. © 2019 Zibeline International Publishing Sdn. Bhd. All rights reserved.Item Displacement characteristics of a piezoactuator-based prototype microactuator with a hydraulic displacement amplification system(Korean Society of Mechanical Engineers, 2015) Rao, M.; Rao, R.In this study, a new piezoactuator-based prototype microactuator is proposed with a hydraulic displacement amplification system. A piezoactuator is used to deflect a diaphragm which displaces a certain volume of hydraulic fluid into a smaller-diameter piston chamber, thereby amplifying the displacement at the other end of the piston. An electro-mechanical model is implemented to estimate the displacement of a multilayer piezoelectric actuator for the applied input voltage considering the hysteresis behavior. The displacement characteristics of the proposed microactuator are studied for triangular actuation voltage signal. Results of the experiments and simulation of the displacement behavior of the stacked piezoactuator and the amplified displacement of the prototype actuator were compared. Experimental results suggest that the mathematical model developed for the new piezoactuator-based prototype actuator is capable of estimating its displacement behavior accurately, within an error of 1.2%. © 2015, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.Item Investigation on the performance of valveless pump for microdelivery of the fluid, fabricated using tool-based micromachining setup(World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2017) Veeresha, R.K.; Rao, M.; Rao, R.; Tauro, A.M.Micropump is an integrated part of microfluidic system and is a boon to the field of miniaturization, owing to its helping hand in numerous applications mainly in biomedical, electronic cooling, fuel cells, spacecraft, etc. In this paper, an attempt is made to design and fabricate valveless pump, with active and passive valves. The actuation element used is piezowafer, piezowafer was experimentally tested and compared with simulated values from ANSYS for its peak displacement and these displacements were used to find volume pumped by pump. The pumping volumes found by experimentation are in good agreement with the simulated results. Further fabrication of valveless pump is carried out by using tool-based micromachining center which is a novel type of fabrication technique in micromachining. Through experiments, the optimum frequency of the pump was found to be 60Hz at an actuating voltage of 150V. The maximum head that a pump could pump was found to be 0.051m with pressure of 500.13Pa. The flow rate of the pump had a decreasing trend with increase in head. © 2017 World Scientific Publishing Company.Item Investigating the performance of electromagnetic pump fabricated using tool based micromachining setup for microdelivery of fluid(Bangladesh University of Engineering and Technology, 2019) Veeresha, R.K.; Karegoudra, M.K.; Rao, M.; Rao, R.; Kumar, N.Micropumps play an important role in the delivery of insulin, hormonal and pain management for biomedical application. The main reason for the micropump is to pump a small amount of fluid to the target area and also control the pumping fluid. Electromagnetically operated pump fabricated using tool-based micromachining setup for the micro-delivery of the fluid. The electromagnetic pump was supplied with an input voltage of 6V-12V and at different frequencies starting from 1Hz to 5Hz with the increment of 1Hz. The maximum head developed is at a frequency of 3Hz which the optimum frequency for this configuration of an electromagnetic pump is. The maximum head obtained at this optimal frequency is 25mm. Finally, in order to measure the flow rate of the electromagnetic pump the pump was actuated at 3Hz frequency alone by varying the head of the micropump from 4 to 20mm. © 2019 Bangladesh University of Engineering and Technology. All rights reserved.Item Experimental investigation on the suitability of flexible pressure sensor for wrist pulse measurement(Springer Verlag service@springer.de, 2019) Sukesh Rao, S.; Rao, R.Pulse examination at the radial artery of the wrist is a most apparent diagnosis technique. Wrist pulse carries rich information about the cardiovascular system of human body. An investigation is made here to suggest suitable flexible type of thin film pressure sensor to measure the wrist pulse as per Ayurvedic medicine system. Primary objective of this work is to suggest a sensor which exhibits optimum spatial features and SNR values. Force Sensing Resistor (FSR), piezoresistive and piezoelectric thin film sensors are considered under this study. Piezoelectric sensor shows good performance in the quality of the pulse with 22 dB SNR. Further experimentation is conducted to find out transmissivity, repeatability and susceptibility to motion artifact. Trasnsmissivities of 0.91, 0.68 and 0.64 are obtained for piezoelectric, piezoresistive and FSR sensors respectively. Piezoresistive and FSR show repeatability error of ±8% and ± 7% while measuring pulse amplitude under standard force. Noise due to motion artifact for each type of sensors are recorded and compared with the standard Gaussian distribution function with the help of histogram. Collectively, piezoelectric sensor exhibits good spatial features, high transmissivity and comparatively low susceptibility to motion artifact. © 2018, IUPESM and Springer-Verlag GmbH Germany, part of Springer Nature.Item Design, analysis and testing of flexurally amplified piezoactuator based active vibration isolation system for micromilling(Bangladesh University of Engineering and Technology, 2020) Divijesh, P.; Rao, M.; Rao, R.; Ahmed, R.M.; Sushith, K.Vibration is considered to be one of the limiting factors which affects precise measurements and surface finish of various mechanical components. Active Vibration Isolation is one such effective method which reduces the unwanted vibrations in any mechanical systems in a wide range of frequencies. This paper presents the design, analysis and testing of an active vibration isolation system based on Flexurally Amplified Piezo actuators (FAP1 and FAP2). The proposed set up aims at obtaining 180° out of phase displacement signal to the generated displacement signal using FAPs thereby minimising vibrations at the isolation platform. The maximum displacements of FAP1 and FAP2 obtained for 0-150V sinusoidal peak to peak amplitude at 1Hz frequency was found to be 810?m and 780?m respectively. The experimental displacements obtained were compared with simulated displacements using Forward Bouc-Wen hysteresis model and found very well agreed with each other within 1% error. An attempt has been made to estimate the voltage required for obtaining any desired displacement of FAPs using Inverse Bouc-Wen model through Simulink. The experimental displacements for the corresponding estimated voltages were obtained for FAPs. Finally, the proposed set up was tested by actuating both FAP1 and FAP2 separately and simultaneously for 0-150V at 1Hz frequency and was found that the displacements obtained were 180° out of phase thereby minimizing vibrations at the isolation platform. © 2020 Zibeline International Publishing Sdn. Bhd.. All rights reserved.Item A High Performance Early Acknowledged Asynchronous Pipeline using Hybrid-logic Encoding(Elsevier B.V., 2020) Girija Sravani, K.; Rao, R.This paper details a novel asynchronous pipelining methodology that maximizes the throughput buffering capacity and robustness of gate-level pipelined systems. The data paths in the proposed pipeline style are encoded using hybrid logic encoding scheme, which incorporates simplicity of the single-rail encoding and robustness of the dual-rail encoding. The control path that provides the synchronization between pipeline stages is constructed based on the simple and high-speed early acknowledgment protocol. Further, the proposed pipeline accommodates isolate phase to achieve 100% storage capacity. Two test cases: A 4-bit,10-stage FIFO and a 16-bit adder, have been designed in 90 nm technology to validate the proposed pipeline style. The FIFO has been laid out in the UMC 180 nm process using the cadence tool suite. The post-layout results of FIFO show 12.5% better throughput than the high capacity single-rail pipeline. Simulation results of the adder also reveal that the proposed structure achieves the throughput of 3.44 Giga-items/sec, which is 44.18% higher than the APCDP (Asynchronous pipeline based on constructed critical path) and 11.9% higher than the high capacity single-rail pipelines. © 2019 Elsevier B.V.Item A new blood pressure prediction method using wrist pulse examination(Springer, 2020) Sukesh Rao, M.; Rao, R.Wrist pulse examination plays an imperative role in clinical practice including contemporary medicine systems like Ayurveda. Wrist pulse measurement system can also be used for blood pressure (BP) monitoring. This article proposes an extension of wrist pulse analysis system for BP monitoring. Wrist pulse signals are captured using three piezoelectric thin film sensors at the radial artery of the wrist as per Ayurvedic pulse diagnosis method. The wave features such as Spatial Pulse Transit Time (SPTT) and Spatial Pulse Wave Velocity (SPWV) are extracted from the captured wrist pulses. Pearson’s correlation coefficient is computed to find the correlation between SPTT and BP measured using standard measuring instrument (Omron HEM-6131). A moderate correlation is found between SPTT and Systolic Blood Pressure (SBP) with correlation coefficient of 0.72. SPWV values computed from SPTT are used to develop an empirical model for BP in terms of SPWV. Limitations of the empirical model lead to a theoretical model using Poiseuilli law. The Mean Artery Pressure (MAP) using theoretical model is recorded for 41 participants. The deviation of MAP thus computed as compared to the readings taken from clinically validated BP monitoring device is found to be varying in the range of 4.5 ± 2.3 mmHg. © 2020, IUPESM and Springer-Verlag GmbH Germany, part of Springer Nature.Item Novel Asynchronous Pipeline Architectures for High-Throughput Applications(Springer, 2020) Girija Sravani, K.; Rao, R.This paper introduces two novel high-throughput asynchronous pipeline methods, suitable for gate-level pipelined systems. The proposed methods, named as early acknowledged hybrid (EA-Hybrid) and high-capacity hybrid pipeline with post-detection (PD-Hybrid), use hybrid data paths that can combine the robustness of dual-rail encoding and simplicity of single-rail encoding schemes. The domino logic style has been adopted for constructing the logic gates in each pipeline stage, as it can provide the latch-less feature. The control path of EA-Hybrid is built based on high-speed early acknowledgment protocol, whereas in PD-Hybrid, it is built based on simple and robust 4-phase protocol. Further, both the proposed pipeline styles allow their logic gates into a special state called the isolate phase in addition to precharge and evaluation phases. The isolate phase leads to improvement in pipeline throughput as well as storage capacity. An 8x8 array multiplier has been designed using the proposed pipeline styles and simulated in three different technologies using UMC libraries. In 180 nm technology, the proposed EA-Hybrid method has achieved 40.25% higher throughput and the pipeline style PD-Hybrid has achieved 18.05% higher throughput than the APCDP. © 2020, King Fahd University of Petroleum & Minerals.Item Design of high throughput asynchronous FIR filter using gate level pipelined multipliers and adders(John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2020) Girija Sravani, K.; Rao, R.This work presents the design of an asynchronous digital finite impulse response (FIR) filter suitable for high-performance partial response maximum likelihood (PRML) read channel ICs. A high throughput, low latency FIR filter is the basic requirement for the equalization process in read channels. To achieve the enhancement in speed and reduction in latency of the FIR filter, its computational units are deeply pipelined using high-capacity hybrid (HC-hybrid) logic pipeline method. The designed FIR filter has been simulated using UMC-180 nm and UMC-65 nm technologies. Simulation results show that the asynchronous digital FIR filter can operate up to a throughput of 1.17 Giga items/s in 180 nm and 2.3 Giga items/s in 65 nm technology yet with the latency in the order of ns. © 2020 John Wiley & Sons, Ltd.