Harjeevan Singh

Due to massive developments in underwater applications, the scarcity of bandwidth resources for underwater communication has fuelled the need for more advanced technology in the field of underwater communication. Therefore, a high-speed underwater optical wireless (UOW) link, driven by 16-Quadrature Amplitude Modulation (16-QAM) modulation and polarization division multiplexing, has been proposed in this work to alleviate bandwidth constraints in underwater communication. But the dynamic nature of the underwater link makes it very challenging for conventional methods to model the complex and non-linear relation between key physical link parameters and performance metrics of the underwater link. To overcome this challenge, a data-driven machine learning framework, based on state-of-the-art machine learning models, has been developed in this work to predict the signal-to-noise ratio (SNR) of the proposed underwater link. The proposed underwater link can achieve an underwater range of 17.93 m while ensuring a Forward Error Correction (FEC) compatible bit error rate (BER) of 3.8 × 10⁻³. Furthermore, a novel closed-form expression of BER for 16-QAM modulation-based UOW link has been derived by considering the combined impact of underwater turbulence, absorption, and scattering. In addition to this, a physics-guided and machine learning-based neural network for adaptive modulation (PML-NN-AM) has been proposed in this work for switching modulation order as per the channel conditions, and it has demonstrated good agreement with the analytical adaptive modulation benchmark.

The extraction of metallic nanoparticles (MNPs) from waste electrical and electronic equipment (WEEE) has gained extensive attention from researchers for eco-friendly, reliable, and sustainable alternative protocol over the traditional linear economic approach (make-use-dispose) for boosting the circular economy. A plethora of MNPs including metals/metal oxide nanoparticles having a size dimension ranging from 1–100 nanometers (nm) have been extracted from these WEEE by using different chemical, physical, and biological methods. Recovery of certain precious MNPs can be achieved by dismantling and recycling electronic waste items in the form of gold (Au), platinum (Pt), zinc oxide (ZnO), silver (Ag), and copper oxide (CuO). These MNPs provide a huge range of applications such as antibacterial, therapeutic, target drug delivery, and biotechnological applications. This comprehensive review provides in-depth knowledge of the synthesis of MNPs using different techniques from WEEE and delves into their potential applications in biomedical fields with in-depth mechanisms. This article also discussed global challenges and opportunities in this area for adopting the concept of circular economy to conserve natural resources for future generations and hence create a greener environment and protect our planet.

This work aims to investigate the performance of Free Space Optical Communication link under average and worst rain weather conditions of India. The meteorological data related to rainfall, from 2014 to 2017, was obtained from the Indian Meteorological Department for six different locations of India, representing the inland and coastal areas. The attenuation coefficient due to rain for all the locations has been calculated using mathematical models. The performance analysis of Wavelength Division Multiplexing based Free Space Optical Communication system has been analyzed, by incorporating the attenuation due to rain for all considered locations, in terms of received power, signal to noise ratio, bit error rate and eye diagrams. The inland location of Hyderabad has given the best results in terms of above mentioned parameters as it has recorded minimum average rainfall of 2.35 mm/hr with minimum attenuation coefficient of 1.91 dB/km and can support a link range of 5.43 km, corresponding to bit error rate of order of 10^-9 under average rain weather conditions. On the other hand, the average rainfall is maximum for the coastal area of Mumbai with a value of 7.31 mm/hr, resulting in maximum attenuation coefficient of 4.08 dB/km and the maximum link range is limited to 3.48 km, corresponding to bit error rate of order of 10^-9 under average conditions of rain weather. Similarly, the inland locations of India have delivered a better link performance as compared to coastal areas under worst rain weather conditions also. So it has been concluded that the coastal areas of India have shown major degradation in the performance of the FSOC link as compared to inland locations of the country.