National Institute of Technology, Silchar

About: National Institute of Technology, Silchar is a education organization based out in Silchar, Assam, India. It is known for research contribution in the topics: Control theory & Electric power system. The organization has 1934 authors who have published 4219 publications receiving 41149 citations. The organization is also known as: NIT Silchar.

Natural convection heat transfer and entropy generation in a porous rhombic enclosure: influence of non-uniform heating

Abstract: In this paper, we present a numerical investigation of natural convection heat transfer and entropy generation for a rhombic enclosure with inclination angle, ϕ = 30°, filled with a porous medium. The left and right surface walls of the enclosure are confined to cold temperature bath while we impart non-uniform, varying temperature distribution with unequal phase angles along the top and bottom wall. The flow inside the enclosure is steady, two-dimensional, incompressible and laminar, and the working fluid is air (Pr = 0.71). Numerical experiments have been performed using finite element method-based software COMSOL Multiphysics 5a for Darcy number and Rayleigh number in the extent of 10−4–10−2 and 103–106, respectively, in addition to phase deviation angles varying in the range from 0 to π. The amplitude parameter associated with the temperature delineation of the bottom and top walls is kept constant. The realizations from the numerical investigation are exhibited by streamlines and isotherms, local and average heat transfer Nusselt number along with the local distribution of heat transfer and fluid friction irreversibilities. The rate of heat transfer demonstrates non-monotonic trends and can be considerably influenced by the interplay of the phase shift angle, Rayleigh number and Darcy number. Upon increasing the value of phase shift angle from 0 to π, average Nusselt number initially decreases and thereafter shows an increase in its value. As the Darcy number increases, average Nusselt number for the bottom wall increases, while for the top wall it strongly depends on phase shift angle. In terms of entropy generation, it is found that the significant contributor to irreversibility is induced by heat transfer and the location of maximum entropy varies with the change in phase angle. More specifically, minimum entropy generation for any value of Rayleigh number and Darcy number is obtained for a phase shift angle of π/4 and maximum for 3π/4. The concomitant transport characteristics bear significance from the context of design of thermal systems pertaining to the theme of non-uniform heating with the phase angle being a crucial design parameter.

Biomolecule-assisted solvothermal synthesis of Cu2SnS3 flowers/RGO nanocomposites and their visible-light-driven photocatalytic activities

Abstract: Elimination of organic pollutants from wastewaters under visible-light irradiation is a venerable challenge in the fields of environmental and material science. In this work, we present a facile eco-friendly method to fabricate novel Cu2SnS3 flowers/RGO (Cu2SnS3/RGO) nanocomposites via a solvothermal method using L-cysteine as a sulphur source and linker. The crystal structure, morphology, purity, spectroscopic, and charge carrier separation properties of the synthesized samples were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), and X-ray energy-dispersive spectroscopy (EDS), Raman spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and electrochemical impedance spectroscopy (EIS). The photocatalytic performance of the Cu2SnS3/RGO nanocomposites was evaluated by photocatalytic decolorization of eosin under visible-light irradiation. Results showed that the Cu2SnS3/RGO (3%) nanocomposite exhibits enhanced photocatalytic activity compared with the pure Cu2SnS3. The improved photocatalytic activity of the nanocomposite was mainly attributed to the formation of well-defined interface between Cu2SnS3 and graphene sheets, which greatly enhance the charge carrier separation efficiency in the Cu2SnS3 semiconductor.

Studies of structural, impedance spectroscopy and magnetoelectric properties of (SmLi) 1/2 (Fe 2/3 Mo 1/3 )O 3 electroceramics

Abstract: In the present communication, studies of some physical properties (i.e., crystal data, permittivity, impedance, electrical cobnduction and magnetic) of a multiferroic material with a chemical composition (SmLi)1/2(Fe2/3Mo1/3)O3 have been reported. Thermogravimetric analysis of the compound, prepared by cost effective ceramic technology processing, was executed to check the mass loss as well as the required decomposition temperature of the ingredients. An analysis of X-ray spectra or pattern suggests that the crystallization phase or cystal system of the compound at room temperature is orthorhombic. The broad studies of dielectric properties {relative dielectric constant (er), and tangent loss (tan δ)} display their independence of temperature and frequency in the rage of (30–375 °C) and (1 kHz–1 MHz) respectively. The impedance spectroscopic technique has provided a considerable significant information regarding the grain, grain boundary contribution within the sample and relaxation mechanism of the compound. The occurrence of negative temperature coefficient behaviour (NTCR) is depicted by the further analysis of impedance parameters. The frequency–temperature dependence of conductivity follows the Johnson’s power Universal law. The Arrhenius plot (i.e., variation of electrical conductivity with temperature) is used to calculate the activation energy. Analysis of magnetization (M–H) loop shows weak ferromagnetism of the compound. The material possesses significantly high magnitude of magnetoelectric coefficient of 3.0 mV Cm− 1 Oe− 1.

A multi-layered dual-band on-body conformal integrated antenna for WBAN communication

Abstract: This article presents a dual-band, multi-layered on-body conformal metamaterial (MTM) integrated antenna for Wireless Body Area Network (WBAN) communication. The frequency bands range from 3.2 GHz to 3.5 GHz and 3.9 GHz to 4.3 GHz. A zero-reflection-phase based MTM comprises of the 2 × 2 array of H-shaped unit-cell is installed beneath the monopole antenna to suppress the back radiations, and enhance the gain. The characterization of the unit-cell is done in terms of its reflection and transmission characteristics, refractive index, and material characteristics. The integration of the MTM brings down the peak 1-g-averaged SAR to 0.174 W/kg and 0.207 W/kg at the respective bands of the conformal configuration for a body-antenna separation of 1 mm. The proposed configuration proffers peak realized antenna gain of 4.54 dBi and 4.71 dBi, and Front to Back Ratio (FBR) of 11.79 dB and 12.98 dB at the respective frequency bands. The performance of the proposed antenna is rigorously analyzed against structural deformation, operating frequency, gain, and FBR. The measured performance of antenna agrees well with that of simulated results.