Browsing by Author "Shikha Dubey"

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Facile and green synthesis of highly dispersed cobalt oxide (Co3O4) nano powder: Characterization and screening of its eco-toxicity
(Elsevier B.V., 2018) Shikha Dubey; Jay Kumar; Ashok Kumar; Yogesh Chandra Sharma
A novel green synthesis of cobalt oxide (Co3O4) nanoparticles using latex of Calotropis procera via simple precipitation method at room temperature was investigated. An extensive characterization of the product was carried out using X-ray diffractometry (XRD), Differential scanning calorimetry (DSC), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and UV–Visible spectroscopy. The results of the characterization confirmed that the synthesized nanomaterial is highly dispersed. TEM analysis revealed that the nano particles are having an average size around 10 nm. The eco-toxic investigation suggested that the particles are non-toxic and safe towards the environment. This green strategy proves to be an effective, fast, simple and cost-effective approach for the synthesis of Co3O4 nanoparticles for various applications. © 2018 The Society of Powder Technology Japan
Speech Enhancement using Adaptive Mean Median Deviation and EMD Technique
(Institute of Electrical and Electronics Engineers Inc., 2019) Shikha Dubey; Ashish Kumar Singh; Manoj Kumar Singh
During the acquisition of the speech signal by the non-contact Speech Sensor (SS), the signal is degraded by severe colored noises which are non-linear and non-uniform in nature. Therefore, in this study, a new approach for advancing the speech enhancement technique is proposed to suppress these noises from the acquired speech signal. This technique is based on the adaptive thresholding, which uses Mean Median Deviation (MMD) method to determine adaptive threshold points, and Empirical Mode Decomposition (EMD) method. This algorithm has been validated by simulation data, and results of the proposed algorithm have been compared with other existing enhancement algorithms. Spectrograms and Signal to Noise Ratio (SNR) comparison are used to analyze the quality of the enhanced speech signal. From the results, we demonstrate that the proposed algorithm offers better speech enhancement than previously existing speech enhancement techniques. © 2019 IEEE.
The occurrence of various types of disinfectant by-products (trihalomethanes, haloacetic acids, haloacetonitrile) in drinking water
(Elsevier, 2020) Shikha Dubey; Deepak Gusain; Yogesh Chandra Sharma; Faizal Bux
Disinfection of drinking water supplies with various disinfectants has been integral for maintaining high microbial quality of drinking water. Disinfectant inactivates disease-causing organisms and effectively reduces waterborne diseases to ensure safe consumption of water. However, an unintended chemical reaction between disinfectants and naturally occurring organic and inorganic precursors or anthropogenic compounds in the source waters results in the generation of a number of disinfection by-products (DBPs) including trihalomethanes, haloacetic acids, and haloacetonitrile in drinking water. Due to potential adverse health effects (from cancer induction to birth defects, etc.) posed by these geno- and cytotoxic DBPs on exposure, they have received great concern worldwide and thus are regulated by the United States Environmental Protection Act in the water industry. The objective of this chapter is to provide an insight into the apprehension of DBP generation in drinking water, occurrence, types of DBPs, and associated adverse health effects. © 2020 Elsevier Ltd. All rights reserved.