Faculty Publications
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Item Abrasive wear behavior of granite-filled glass-epoxy composites by SiC particles using statistical analysis(2011) Basavarajappa, .S.; Manjunath Yadav, S.M.; Kumar, S.; Arun, K.V.; Narendranath, S.This experimental investigation deals with the evaluation of abrasive wear behavior of Glass Epoxy (G-E) composites on pin-ondisc test rig. A plan of experiments, based on the Taguchi Design of Experiments, was performed to acquire data in controlled way. An orthogonal array and the analysis of variance were employed to investigate the percentage of contribution of various process parameters like sliding speed, applied load, sliding distance and their interactions affecting the abrasive wear volume loss of composites. The correlations between the various factors affecting the abrasive wear behavior of composites were obtained by using multiple linear regression equations. The obtained results indicate that applied load and sliding distance were the wear factors that have the highest physical as well as statistical influence on the abrasive wear behavior of both filled and unfilled G-E composites. A good agreement between the predicted and actual wear resistance was observed within±12%. © Taylor & Francis Group, LLC.Item Studies on development of high performance, self-compacting alkali activated slag concrete mixes using industrial wastes(Elsevier Ltd, 2019) Manjunath, R.; Narasimhan, M.C.; Umesh, K.M.; Kumar, S.; Bala Bharathi, U.K.In the present study, development of a class of High Performance Alkali Activated Slag Concrete mixes (hereafter referred to as HPAASC mixes) is discussed. These mixes are developed using three industrial wastes from Iron and Steel industry. While Ground granulated blast furnace slag (GGBFS) was used as the main binder, in the development of these HPAASC mixes, steel slag sand and Electric Arc Furnace slag (EAF slag) have been employed in the fine aggregate and coarse aggregate fractions of them. Higher flow characteristics, as those of self-compacting concrete mixes, as well as enhanced mechanical strength properties of these mixes are discussed in detail. The alkaline solutions used consist mixtures of sodium hydroxide and sodium silicate solutions, with a constant activator modulus (ratio of SiO2/Na2O) of one maintained in them. Taguchi’ design of experiments methodology was used to reduce the experimental efforts. The formulation of all the mixes developed herein was based on Taguchi's L-9 orthogonal array. Flow and strength properties of a set of nine mixes were used for performance evaluation purposes in an initial, calibration phase. Strength prediction equations were derived based on such results, the predictive capability of which were then assessed and ascertained with actual results of experiments on the next six new mixes, in the prediction phase. Test results indicated a higher flowability values for all the mixes (with slump flows greater than 700 mm), good filling and passing abilities, all satisfying the EFNARC (European Federation of Specialist Construction Chemicals and Concrete Systems) recommendations for SCC mixes. Higher compressive strengths (65–90 MPa), split-tensile strengths (4.8–5.3 MPa), flexural strengths (6.5–7 MPa), and Modulus of Elasticity (30.4–36.2 GPa) were observed along with lower water absorption values (2.1–2.7%) for all the HPAASC mixes tested herein. Microstructure studies were conducted on samples from the fractured surfaces of test specimens from different mixes, using advanced SEM, EDX and XRD analyses and the results are discussed. © 2018 Elsevier LtdItem Highly robust X-band quasi circulator-integrated low-noise amplifier for high survivability of radio frequency front-end systems(John Wiley and Sons Ltd, 2021) Vignesh, R.; Gorre, P.; Song, H.; Kumar, S.In this brief, an X-band quasi circulator (QC)-integrated low-noise amplifier (LNA) implemented in 65-nm Complementary Metal Oxide Semiconductor (CMOS) technology is presented. This work is the first QC-LNA for the X-band to the author's best knowledge, which achieves 30-dB flat gain in 8–12 GHz with only 0.5-dB variation across the band. This QC-LNA uses two-stage current reused techniques with variable impedance load. QC provides the minimum insertion loss of 0.9 dB with good return and isolation losses. Statistical analysis is presented for QC-LNA to predict the percentage error tolerance. Quasi-Newton (QN) control algorithm is used to optimize the parameter of the whole design. The design of experiment (DoE) is performed to claim the contribution towards gain, return loss, and noise figure. The proposed LNA measurement provides a minimum NF of 1 dB at 9.5 GHz, which remains less than 1.4 dB across 8–12 GHz. The fabricated LNA works with a supply voltage of 1.2 V and is unconditionally stable across the frequency. The calculated chip area is 0.84 × 0.52 mm2. This QC-LNA exhibits an input and output 1-dB compression point (IP1dB and OP1dB) of ?15 and +13.8 dBm, respectively. It also exhibits third-order input and output intercept point (IIP3 and OIP3) of +10 dBm and of +40 dBm, respectively. The proposed QC-LNA draws only 8.7 mA from 1.2 V. © 2021 John Wiley & Sons, Ltd.Item A novel wide bandwidth FBSSIR integrated low noise amplifier for satellite navigational receiver system(Elsevier Ltd, 2021) Vignesh, R.; Gorre, P.; Kumar, S.This paper presents a Folded Butterfly Stub Stepped Impedance Resonator (FBSSIR) integrated low noise amplifier (LNA) implemented using packaging technology for the satellite navigation receiver system. By employing a novel structural deformation of a stepped-impedance-resonator (SIR), the proposed FBSSIR is achieved with a more compact structure, controllable transmission zero, adjustable center frequency, and adjustable bandwidth. The designed FBSSIR acts as a filter, and the input-output matching network is integrated into the proposed core LNA circuit. The Design-of-experiment (DoE) analysis is performed to analyze the passive component's sensitivity becoming desensitized, while statistical analysis is presented for the proposed FBSSIR integrated LNA to predict the percentage error tolerance. Its measurement result provides gain above 22 dB in the wide bandwidth from 1.6 GHz to 2.5 GHz, minimum NF of 2.7 dB at 1.8 GHz, which varies from 3 dB to 4.5 dB. The calculated area of FBSSIR integrated LNA is 10.7 × 2 cm2, while LNA is 3.3 × 1.6 cm2. It exhibits an input and output 1-dB compression point (IP1dB & OP1dB) of ?23dBm and +2.3dBm. © 2021Item A K/Ka-Band Switchless Reconfigurable 65 nm CMOS LNA Based on Suspended Substrate Coupled Line(Institute of Electrical and Electronics Engineers Inc., 2022) Vignesh, R.; Gorre, P.; Song, H.; Kumar, S.This article presents a K/Ka (18-40) GHz dual-band switch-free reconfigurable 65nm CMOS Low-Noise Amplifier (LNA) realized by inter-stage and output-stage Suspended-Substrate Coupled-Lines (SSCL) for the first time to the author's best knowledge. The amplified input signal from the broadband drive stage is divided into two parallel single band stages by the proposed inter-stage SSCL. Two split-band signals are amplified by the corresponding High-band (Ka) and Low-band (K) stages. The proposed output-stage SSCL combines the amplified two single-bands at the output. The proposed SSCL also provides the required network matching to the LNA. The single band of operation can be achieved by simply turning off the unused transistor band's drain voltage. The proposed LNA achieves a maximum noise figure (NF) taken in dual-mode of 1 dB and 1.2 dB and a gain of 27 dB with 0.2 dB and 2 dB variation in the K-band and Ka-band, respectively. Statistical analysis and design of experiment (DoE) are applied to predict the percentage error tolerance and validate the contribution of the parameters towards gain, return loss, and noise figure. This LNA exhibits an input and output 1-dB compression point (IP1dB OP1dB), third-order input output intercept point (IIP3 OIP3) of -17/-16 dBm, +7.1/6.4 dBm, 0 dBm and +25/+23 dBm over 18-24/25-40 GHz respectively. The fabricated LNA draws 21.4 mA from 1.2 V with a size of 0.61 $\times $ 0.92 mm2. © 2013 IEEE.