Journal Articles

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Author: search.filters.author.Ahmed, S.Has files: No

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    Rapid sonochemical synthesis of copper doped ZnO grafted on graphene as a multi-component hierarchically structured visible-light-driven photocatalyst
    (Elsevier Ltd, 2021) Shenoy, S.; Ahmed, S.; Lo, I.M.C.; Singh, S.; Sridharan, K.
    Three-dimensional (3D) hierarchical structures (HSs) have demonstrated excellent properties for various applications that are attributable to their distinctive micro-sized architecture with nanoscale substructures. Recently, the ultrarapid sonochemical approach was found to be an effective strategy for synthesizing single component HSs with uniform morphologies in comparison to the direct precipitation technique. We here report the fabrication of copper doped zinc oxide grafted on graphene layers (ZnO-Cux-GOy) for exploring the capability of this ultrarapid approach for synthesizing multi-component HSs. Interestingly, the morphology of ZnO-Cux-GOy HSs studied through electron microscopy revealed the growth of ZnO HSs decorated with Cu nanoparticles and interconnected by graphene layers. ZnO-Cux-GOy HSs demonstrated three-fold higher efficiency in the photodegradation of ibuprofen (IBU) under visible light irradiation in comparison to pristine ZnO HSs, which is attributable to the combined influence of the doped Cu2+ ions and graphene, enabling improved visible light absorption and inhibiting the recombination of photogenerated charges. Thus, the novel ultrarapid sonochemical synthesis strategy demonstrated here is anticipated to open up a new horizon for the time-saving and scalable design of multi-component HSs of various materials for a myriad of applications. © 2021 Elsevier Ltd
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    A Reduced Component Count Self-Balance Quadruple Boost Seventeen-Level Switched Capacitor Inverter
    (Institute of Electrical and Electronics Engineers Inc., 2024) Ahmed, S.; Raushan, R.; Ahmad, M.W.
    A switched capacitor multilevel inverter (SCMLI) enables high-quality output voltage waveforms for various industrial and renewable energy applications. SCMLI uses a combination of capacitors and switches to generate multiple voltage levels from a single dc source, thereby reducing the overall cost and size of the system. This article proposes a novel configuration of a 17-level SCMLI. The proposed converter can boost four times the input voltage by exploiting the series-parallel connection of capacitors with the dc voltage source. With simple pulsewidth modulated (PWM) control, the capacitor voltages are inherently balanced under different loading conditions. Furthermore, for 11 switches, only seven independent switching signals are required. Loss analysis reveals that the proposed SCMLI has significantly reduced conduction losses, capacitor ripple voltage, voltage stress, and cost function (CF) when compared with other topologies available in the literature. Finally, the simulation results are obtained at different loads and modulation indexes. The results are experimentally validated with a scaled-down laboratory prototype. © 2024 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.