1,895 research outputs found
The final fate of spherical inhomogeneous dust collapse II: Initial data and causal structure of singularity
Further to results in [9], pointing out the role of initial density and
velocity distributions towards determining the final outcome of spherical dust
collapse, the causal structure of singularity is examined here in terms of
evolution of the apparent horizon. We also bring out several related features
which throw some useful light towards understanding the nature of this
singularity, including the behaviour of geodesic families coming out and some
aspects related to the stability of singularity.Comment: Latex file, uses epsf.sty, 15 pages and 3 eps figures. Paragraph on
role of smooth functions rewritten. Four references added. To appear in
Classical & Quantum Gravit
Utilisation of sea nodules leaching residue for adsorption of Ni(II) ions
Polymetallic sea nodules may be considered as lean grade ore of Cu, Ni & Co. After recovery of these valuable metals, a huge quantity of residue (~70% of ore body) is generated. In the present paper, investigations carried out for the application of leached sea nodule residue for the removal of Ni(II) from aqueous solution by adsorption, are described. Several parameters have been varied to study the feasibility of using residue as potential adsorbent for remediation Ni(II) contaminated water. The adsorption kinetics followed pseudo first-order equation and the rate of adsorption increased with solution temperature. Kinetics data of Ni(II) adsorption was also discussed using diffusion models of Webber-Morris and Dumwald-Wagner models. The equilibrium data was best fitted into Langmuir adsorption isotherm and the maximum adsorption capacities was found to be 15.15 mg g-1 at pH 5.5 and temperature 303 K, which decreased to 10.64 mg g-1 upon raising the solution temperature to 323 K. The activation energy for Ni(II) adsorption onto leached sea nodule residue was 9.56 kJ mol−1 indicated physical sorption. Desorption studies showed successful regeneration of adsorbent and recovery of Ni. This process can be utilised for removal and recovery of Ni from the industrial effluent
Analytical Investigation of Sound Radiation from Functionally Graded Thin Plates Based on Elemental Radiator Approach and Physical Neutral Surface
This paper analyzes the sound radiation behavior of a clamped thin, functionally graded material plate using the classical plate theory and Rayleigh Integral with the elemental radiator approach. The material properties of the plate are assumed to vary according to the power-law distribution of the constituent materials in the transverse direction. The functionally graded material is modeled using a physical neutral surface instead of a geometric middle surface. The effects of the power-law index, elastic modulus ratio, different constituent materials, and damping loss factor on the sound radiation of functionally graded plate are analyzed. It was found that, for the considered plate, the power-law index significantly influences sound power level and radiation efficiency. There exists a critical value of the power-law index for which the corresponding peak of sound power level is minimum. In a wide operating frequency range, approximately 500–1500 Hz, this research suggests that the radiation efficiency is lower for the power-law index equal to 0 and 1. However, for very low frequencies (less than 250 Hz), the power-law index does not affect radiation efficiency significantly. Further, as the modulus ratio increases, the sound power peak decreases for a given power-law index. For the given material constituents of the functionally graded plate, the different values of damping loss factors do not significantly influence radiation efficiency. However, the selection of material constituents affects the radiation efficiency peak
Multi-wavelength Diagnostics of the Precursor and Main phases of an M1.8 Flare on 2011 April 22
We study the temporal, spatial and spectral evolution of the M1.8 flare,
which occurred in NOAA AR 11195 (S17E31) on 22 April 2011, and explore the
underlying physical processes during the precursors and their relation to the
main phase. The study of the source morphology using the composite images in
131 {\deg}A wavelength observed by the SDO/AIA and 6-14 keV revealed a
multiloop system that destabilized systematically during the precursor and main
phases. In contrast, HXR emission (20-50 keV) was absent during the precursor
phase, appearing only from the onset of the impulsive phase in the form of
foot-points of emitting loop/s. This study has also revealed the heated
loop-top prior to the loop emission, although no accompanying foot-point
sources were observed during the precursor phase. We estimate the flare plasma
parameters viz. T, EM, power-law index, and photon turn-over energy by forward
fitting RHESSI spectral observations. The energy released in the precursor
phase was thermal and constituted ~1 per cent of the total energy released
during the flare. The study of morphological evolution of the filament in
conjunction with synthesized T and EM maps has been carried out which reveals
(a) Partial filament eruption prior to the onset of the precursor emission, (b)
Heated dense plasma over the polarity inversion line and in the vicinity of the
slowly rising filament during the precursor phase. Based on the implications
from multi-wavelength observations, we propose a scheme to unify the energy
release during the precursor and main phase emissions in which, the precursor
phase emission has been originated via conduction front formed due to the
partial filament eruption. Next, the heated leftover S-shaped filament has
undergone slow rise and heating due to magnetic reconnection and finally
erupted to produce emission during the impulsive and gradual phases.Comment: 16 Pages, 11 Figures, Accepted for Publication in MNRAS Main Journa
Adoption of AI-empowered industrial robots in auto component manufacturing companies
The usage of AI-empowered Industrial Robots (InRos) is booming in the Auto Component Manufacturing Companies (ACMCs) across the globe. Based on a model leveraging the Technology, Organisation, and Environment (TOE) framework, this work examines the adoption of InRos in ACMCs in the context of an emerging economy. This research scrutinises the adoption intention and potential use of InRos in ACMCs through a survey of 460 senior managers and owners of ACMCs in India. The findings indicate that perceived compatibility, external pressure, perceived benefits and support from vendors are critical predictors of InRos adoption intention. Interestingly, the study also reveals that IT infrastructure and government support do not influence InRos adoption intention. Furthermore, the analysis suggests that perceived cost issues negatively moderate the relationship between the adoption intention and potential use of InRos in ACMCs. This study offers a theoretical contribution as it deploys the traditional TOE framework and discovers counter-intuitively that IT resources are not a major driver of technology adoption: as such, it suggests that a more comprehensive framework than the traditional RBV should be adopted. The work provides managerial recommendations for managers, shedding light on the antecedents of adoption intention and potential use of InRos at ACMCs in a country where the adoption of InRos is in a nascent stage
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