Indian Institute of Technology Madras

About: Indian Institute of Technology Madras is a facility organization based out in Chennai, Tamil Nadu, India. It is known for research contribution in the topics: Catalysis & Heat transfer. The organization has 20118 authors who have published 36499 publications receiving 590447 citations.

Natural convection of nano-fluids

Abstract: Fluids with nano size solid particles suspended in them have been given the name nano-fluid which in recent studies have shown tremendous promise as heat transfer fluids. However, before suggesting such fluids for applications a thorough knowledge of physical mechanism of heat transfer in such fluids is wanted. The present study deals with one such aspect of natural convection of nano fluids inside horizontal cylinder heated from one end and cooled from the other. An apparently paradoxical behaviour of heat transfer deterioration was observed in the experimental study. Nature of this deterioration and its dependence on parameters such as particle concentration, material of the particles and geometry of the containing cavity have been investigated. The fluid shows characters distinct from that of common slurries.

The relationship between service quality and customer satisfaction – a factor specific approach

Abstract: The relationship between service quality and customer satisfaction has received considerable academic attention in the past few years. But the nature of the exact relationship between service quality and customer satisfaction (especially in the way the two constructs have been operationalized) is still shrouded with uncertainty. Many researchers have operationalized customer satisfaction by using a single item scale and many others have used multiple item scales. The present study adopts a different approach and views customer satisfaction as a multi dimensional construct just as service quality, but argues that customer satisfaction should be operationalized along the same factors (and the corresponding items) on which service quality is operationalized. Based on this approach, the link between service quality and customer satisfaction has been investigated. The results have indicated that the two constructs are indeed independent but are closely related, implying that an increase in one is likely to lead to an increase in another.

GW190521: A Binary Black Hole Merger with a Total Mass of 150 M

Abstract: On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85_{-14}^{+21} M_{⊙} and 66_{-18}^{+17} M_{⊙} (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65 M_{⊙}. We calculate the mass of the remnant to be 142_{-16}^{+28} M_{⊙}, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is 5.3_{-2.6}^{+2.4} Gpc, corresponding to a redshift of 0.82_{-0.34}^{+0.28}. The inferred rate of mergers similar to GW190521 is 0.13_{-0.11}^{+0.30} Gpc^{-3} yr^{-1}.

Ultralayered Co3O4 for High-Performance Supercapacitor Applications

Abstract: Ultralayered Co3O4 structures with high porosity have been synthesized by a facile homogeneous precipitation process under hydrothermal conditions. The superstructures consist of well-arranged micrometer length rectangular 2D flakes with high specific surface area, pore volume, and uniform pore size distribution. The electrochemical measurements demonstrate that charge storage occurs in ultralayered Co3O4 due to reversible redox reactions. The charge–discharge study shows that the material is capable of delivering very high specific capacitance of 548 F g–1 at a current density of 8 A g–1 and retains 66% of capacitance at 32 A g–1. The charge–discharge stability measurements show excellent specific capacitance retention capability, ca. 98.5% after 2000 continuous charge–discharge cycles at high current density of 16 A g–1. The exceptional cyclic, structural, and electrochemical stability at higher current rate with ∼100% Coulombic efficiency, and very low ESR value from impedance measurements promise good...

Wide-band planar monopole antennas

Abstract: The circular disc monopole (CDM) antenna has been reported to yield wide-impedance bandwidth. Experiments have been carried out on a CDM that has twice the diameter of the reported disc with similar results. New configurations are proposed such as elliptical (with different ellipticity ratios), square, rectangular, and hexagonal disc monopole antennas. A simple formula is proposed to predict the frequency corresponding to the lower edge of the bandwidth for each of these configurations. The elliptical disc monopole (EDM) with ellipticity ratio of 1.1 yields the maximum bandwidth from 1.21 GHz to more than 13 GHz for voltage standing wave ratio (VSWR)<2.