Journal Articles
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Item Influence of Refractory Elements on Mechanical Properties of High Entropy Alloys(Springer, 2021) Kumar Sinha, A.K.; Soni, V.K.; Chandrakar, R.; Kumar, A.High entropy alloys (HEAs) have become the most popular among the materials scientists and researchers due to their attributes like high strength, hardness and corrosion resistance when compared to conventional alloys. For sprawling use of HEAs in various domains such as aerospace, structural and automobile, it is necessary for researchers to explore more number of HEAs. In this endless endeavour of exploration, researchers have also developed refractory HEAs which possess better mechanical properties when compared to conventional HEAs. But, HEAs (without refractory elements) are more economical than refractory HEAs. This is due to the fact that most of the refractory elements are expensive. The present work focuses on the effect of refractory elements, namely, Mo, W, Ta, Nb, Ti and V on mechanical properties of HEAs. This review also provides an insight into the phase evolution in HEAs due to addition of refractory elements. Moreover, it also unfolds research gaps from past literature, which shows that there is scarcity of literature on dynamic characteristics, fatigue and creep analysis of Hf, Zr, Si and Cr based HEAs. © 2021, The Indian Institute of Metals - IIM.Item A review of various materials for additive manufacturing: Recent trends and processing issues(Elsevier Editora Ltda, 2022) Srivastava, M.; Rathee, S.; Patel, V.; Kumar, A.; Koppad, P.G.Tremendous growth has been witnessed in the field of additive manufacturing (AM) technology over the last few decades. It offers a plethora of applications and is already being utilized in almost every sphere of life. Owing to inherent differences between each AM technique, newer fields of research consistently emerge and demand attention. Also, the innovative applications of AM open up newer challenges and thus avenues for focused attention. One such avenue is AM materials. Raw material plays an important role in determining the properties of fabricated part. The type and form of raw material largely depend on the type of AM fabricators. There is a restriction on material compatibility with most of the established AM techniques. This review aims to provide an overview of various aspects of AM materials highlighting the progress made especially over the past two decades. © 2022 The Author(s).Item A Review on Mechanical Properties of Natural Fibre Reinforced PLA Composites(Bentham Science Publishers, 2023) Kumar Sinha, A.K.; Rao, K.R.; Soni, V.K.; Chandrakar, R.; Sharma, H.K.; Kumar, A.Presently, scientists and researchers are in an endless quest to develop green, recyclable, and eco-friendly materials. Natural fibre reinforced polymer composites became popular among materialists due to their lightweight, high strength-to-weight ratio, and biodegradability. However, all-natural fibre reinforced polymer composites are not biodegradable. Polymer matrices like poly-lactic acid (PLA) and poly-butylene succinate (PBS) are biodegradable, whereas epoxy, polypropylene, and polystyrene are non-biodegradable polymer matrices. Besides biodeg-radability, PLA has been known for its excellent physical and mechanical properties. This review emphasises the mechanical properties (tensile, flexural, and impact strengths) of natural fibre-reinforced PLA composites. Factors affecting the mechanical properties of PLA composites are also discussed. It also unveils research gaps from the previous literature, which shows that limited studies are reported based on modeling and prediction of mechanical properties of hybrid PLA composites reinforcing natural fibres like abaca, aloe vera, and bamboo fibres. © 2023 Bentham Science Publishers.Item The heart rate is a non-stationary signal, and its variation can contain indicators of current disease or warnings about impending cardiac diseases. The indicators can be present at all times or can occur at random, during certain intervals of the day. However, to study and pinpoint abnormalities in large quantities of data collected over several hours is strenuous and time consuming. Hence, heart rate variation measurement (instantaneous heart rate against time) has become a popular, non-invasive tool for assessing the autonomic nervous system. Computer-based analytical tools for the in-depth study and classification of data over day-long intervals can be very useful in diagnostics. The paper deals with the classification of cardiac rhythms using an artificial neural network and fuzzy relationships. The results indicate a high level of efficacy of the tools used, with an accuracy level of 80-85%. © IFMBE: 2004.(Classification of cardiac abnormalities using heart rate signals) Acharya, A.U.; Kumar, A.; Subbanna Bhat, P.; Lim, C.M.; Iyengar, S.S.; Kannathal, N.; Krishnan, S.M.2004Item Effect of soil parameters on modulus of resilience based on portable falling weight deflectometer tests on lateritic sub-grade soils(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) George, V.; Kumar, A.The use of portable falling weight deflectometers (PFWDs) has gained prominence among pavement engineers in the characterisation of soil sub-grade based on modulus of stiffness. The values of modulus of resilience and the corresponding values of the rebound deflection measured using the PFWD are largely influenced by the soil stiffness. The focus of the present investigation is on the study of the effect of soil parameters such as grain size distribution, maximum dry density (MDD) and optimum moisture content (OMC) on the values of modulus of stiffness (E PFWD) obtained using the PFWD for tests performed on lateritic soil blends. Tests were conducted on various blends of lateritic soil samples compacted to MDD at moulding water contents set to the optimum moisture content (OMC), dry-side of optimum at OMC?3% and wet-side of optimum at OMC+3%. The regressions developed between the values of E PFWD and the percentage of fines and the percentage of sand for lateritic and lithomargic soils indicate a strong linear relationship between these variables for tests on un-soaked and soaked soils. The regressions developed will be of immense benefit to pavement engineers in estimating the values of the modulus of resilience for lateritic soils for the design of pavement sub-grades and embankments. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.Item ELBA-NoC: Ensemble learning-based accelerator for 2D and 3D network-on-chip architectures(Inderscience Publishers, 2020) Kumar, A.; Talawar, B.Network-on-chips (NoCs) have emerged as a scalable alternative to traditional bus and point-to-point architectures, it has become highly sensitive as the number of cores increases. Simulation is one of the main tools used in NoC for analysing and testing new architectures. To achieve the best performance vs. cost trade-off, simulators have become an essential tool. Software simulators are too slow for evaluating large scale NoCs. This paper presents a framework which can be used to analyse overall performance of 2D and 3D NoC architectures which is fast and accurate. This framework is named as ensemble learning-based accelerator (ELBA-NoC) which is built using random forest regression algorithm to predict parameters of NoCs. On 2D, 3D NoC architectures, ELBA-NoC was tested and the results obtained were compared with extensively used Booksim NoC simulator. The framework showed an error rate of less than 5% and an overall speedup of up to 16 K×. © © 2020 Inderscience Enterprises Ltd.Item Simulation study of multilayer hybrid plasmonic switch using Franz-Keldysh effect(SPIE spie@spie.org, 2020) Sahu, S.K.; Khoja, R.; Kanu, S.; Kumar, A.; Singh, M.ACMOS compatible three-port all-optical silicon switch working in 1.473 to 1.502 ?m (extinction ratio (ER) = 5.5 dB, ?C = 1.488 ?m) and 1.512 to 1.5306 ?m (ER = 3.079 dB, ?C = 1.52 ?m) bands is demonstrated in this work through numerical simulations. However, in spite of the all optical control, having null refractive index contrast between the transmitting and control waveguides of the switch causes the switching merit to deteriorate because of light leaking from the transmitting waveguide. Later, by employing Franz Keldysh effect-induced absorption coefficient tuning of Si1-x Gex (x = 0.85) to replace the silicon control port of the switch, 2.95-dB leakage reduction in the ON state is achieved, which is assessed in detail. Also, our numerical simulations confirmed the bandwidth of 38 GHz, which suggested a multilayer plasmonic waveguide structure. © 2020 Society of Photo-Optical Instrumentation Engineers (SPIE).Item Performance analysis of RoFSO links with spatial diversity over combined channel model for 5G in smart city applications(Elsevier B.V., 2020) Kumar, A.; Krishnan, P.The smart city concept improves the lives of citizens and optimizes the efficiency of city operations, services through the integration of information and communication technology with the help of the internet of things (IoT) and 5G techniques. The bandwidth demand for 5G, smart city, and IoT applications are fulfilled with wireless optical communications. Particularly, radio over free space optical (RoFSO) communication establishes a very attractive choice for interconnecting central base stations with remote antenna units. In this paper, we consider the transmission of orthogonal frequency division multiplexing (OFDM) radio signals with quadrature amplitude (QAM) modulation format through a free space optical link using spatial diversity mitigation technique. The atmosphere is modeled as the combined channel model which takes into account atmospheric attenuation, turbulence, and pointing errors. The atmospheric turbulence and pointing errors are modeled by Malaga, Beckmann, and Rayleigh distributions. The novel closed form BER expressions are derived for the proposed QAM OFDM RoFSO link with spatial diversity. The results are analyzed and plotted for different weather conditions (clear, haze, light fog), turbulence regimes (weak, moderate, strong), misalignment (weak, enhanced), the order of QAM and number of transceivers. The proposed RoFSO system is highly useful for 5G in smart city applications. © 2020 Elsevier B.V.Item Acoustic response behavior of porous 3D graphene foam plate(Elsevier Ltd, 2020) Kumar, A.; Gunasekaran, V.; Mailan Chinnapandi, L.B.M.; Jeyaraj, J.Sound radiation and sound transmission loss (STL) behavior of porous 3D graphene (3D-GrF) foam plate are presented. Two variable refined plate theory which includes both transverse bending and shear stresses is used to model the plate and Navier's solution is used to calculate the vibration responses while Rayleigh integral is used to analyze the acoustic response. Variation in free vibration frequencies with the nature of porosity distribution is significant for the 3D-GrF plates having higher porosity co-efficient. The natural frequency of the 3D-GrF plate with more porosity around the center and less porosity at the outer surfaces is high. However, resonant amplitudes of the responses and STL of the plates are controlled by both the nature of the porosity distribution pattern and porosity co-efficient. In general, STL of the plate with less porosity around the center and high porosity at the extreme surfaces is high compared to the other cases. © 2020 Elsevier Ltd