Faculty Publications
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Publications by NITK Faculty
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Item A New Kaiser-Bessel Constant Modulus Technique for Smart Antenna Beamforming(Springer Science and Business Media Deutschland GmbH, 2022) Shashidhara, K.S.; Dakulagi, V.; Kaur, J.; Yeap, K.H.; Singh, M.; Ratnesh, R.K.In this work, an improved constant modulus algorithm (CMA) blind beamformer exploiting the Kaiser-Bessel window which is dubbed as ‘KB-CMA’ for the smart antenna system is presented. In array signal processing, especially in beamforming technology, the CMA is one of the most popular methods due to its low complexity. However, this beamformer has a very slow convergence time and has a large side lobe level (SLL). This hinders the utility of the CMA method in dynamic circumstances where the speedy capture of the user signal is required. Also, this method is not suitable in the wireless applications where conditions of the channel are speedily varying. To circumvent this problem and to make the classical CMA suitable for practical applications, we propose an improved CMA. The major advantage of the new method is that its time of convergence is almost several times quicker than the classical CMA. Furthermore, we exploit the Kaiser-Bessel window to suppress the SLLs of the improved CMA. Experimental results demonstrate that the proposed method has fast convergence time and the reduced SLL. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Advancement and challenges in MOSFET scaling(Elsevier Ltd, 2021) Ratnesh, R.K.; Goel, A.; Kaushik, G.; Garg, H.; Chandan, n.; Singh, M.; Prasad, B.In this study, we enlighten about the field effect transistors (FET) and their technologies. As far as very large integration is concerned, researchers are continuously focusing on scaling the transistors in a way to improve the transistors efficiency. In today's era, electronics and semiconductor industries are developing in such a manner that different nano scaled transistors work with low power as well as low cost designs. However, scaling of metal oxide semiconductor field effect transistor (MOSFET) into nanometer scale induces some effects like short channel effects, tunneling effects, and threshold voltage effects etc., which degrade the performance as well as cause challenges to the fabrication process. This review article deals not only with the limitations of scaling and ways to resolve them but also contains detailed study of silicon nanowire and other distinctive nano FET. Moreover, these research finding are helpful in directing the current advancements in MOSFET technology and gave a brief sketch of possible future technologies. © 2021Item Reactive magnetron sputtered–assisted deposition of nanocomposite thin films with tuneable magnetic, electrical and interfacial properties(Springer Science and Business Media B.V. editorial@springerplus.com, 2020) Ratnesh, R.K.; Singh, M.; Pathak, S.; Dakulagi, V.In this work, different magnetic thin films of Ni, NiFe and NiFe2O4 are deposited on the SiO2 substrate using sputtering technique. Our experiments confirmed that thin films possess a good nanocrystalline structure. The key deposition parameters controlling their magnetic properties are sheet resistivity, crystalline structure and microtopography of the sputtered thin film. Besides, the reactive gas oxygen (O2) also plays a leading role in transforming the phase and structure of the ferrite film. The nanocrystalline nature of the ferrite film results in the reduction of overall coercivity (HC). The thickness of the sputtered thin film is in the range of 800–1000 Å. The prepared film exhibits roughness in the range of (~ 0.60 to ~ 0.98 nm). Furthermore, the structural transformation study is performed with X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The quite low roughness, high resistivity and low Hc make NiFe2O4 thin film as a potential candidate for the future spintronics, optoelectronics, photocatalysis and solar cell applications. © 2020, Springer Nature B.V.Item Mango Leaves (Mangifera indica)-Derived Highly Florescent Green Graphene Quantum Dot Nanoprobes for Enhanced On-Off Dual Detection of Cholesterol and Fe2+ Ions Based on Molecular Logic Operation(American Chemical Society, 2024) Ratnesh, R.K.; Singh, M.K.; Kumar, V.; Singh, S.; Chandra, R.; Singh, M.; Singh, J.In the present study, we have engineered a molecular logic gate system employing both Fe2+ ions and cholesterol as bioanalytes for innovative detection strategies. We utilized a green-synthesis method employing the mango leaves extract to create fluorescent graphene quantum dots termed “mGQDs”. Through techniques like HR-TEM, i.e., high-resolution transmission electron microscopy, Raman spectroscopy, and XPS, i.e., X-ray photoelectron spectroscopy, the successful formation of mGQDs was confirmed. The photoluminescence (PL) characteristics of mGQDs were investigated for potential applications in metal ion detection, specifically Fe2+ traces in water, by using fluorescence techniques. Under 425 nm excitation, mGQDs exhibited emission bands at 495 and 677 nm in their PL spectrum. Fe2+-induced notable quenching of mGQDs’ PL intensity decreased by 97% with 2.5 μM Fe2+ ions; however, adding 20 mM cholesterol resulted in a 92% recovery. Detection limits were established through a linear Stern-Volmer (S-V) plot at room temperature, yielding values of 4.07 μM for Fe2+ ions and 1.8 mM for cholesterol. Moreover, mGQDs demonstrated biocompatibility, aqueous solubility, and nontoxicity, facilitating the creation of a rapid nonenzymatic cholesterol detection method. Selectivity and detection studies underscored mGQDs’ reliability in cholesterol level monitoring. Additionally, a molecular logic gate system employing Fe2+ metal ions and cholesterol as a bioanalyte was established for detection purposes. Overall, this research introduces an ecofriendly approach to craft mGQDs and highlights their effectiveness in detecting metal ions and cholesterol, suggesting their potential as versatile nanomaterials for diverse analytical and biomedical applications. © 2024 American Chemical Society.