IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

We report the performance of a slit virtual impactor at high particle mass concentrations (>500μg/L). Transmission efficiency was determined on an individual particle basis by visualization of fluorescent particles embedded in a background matrix of Arizona road dust. No significant difference in transmission efficiency from dilute conditions was observed for a mass loading of 571μg/L. At greater mass loadings (>1000μg/L), the device clogged before a statistically significant data set could be obtained. These results suggest that the performance of a slit virtual impactor is not degraded up to roughly 600μg/L, and may be extended to even larger mass loadings provided that clogging of the nozzle is minimized. © 2004 Elsevier Ltd. All rights reserved.

Department of Applied Mechanics

World University root node

Journal of Aerosol Science

Performance of a slit virtual impactor operated at high particle mass loading

Convective transport behavior of monodisperse supermicron particles has been analyzed in a slit virtual impactor. Particle trajectories were visualized using video imaging of scattered light and fluorescence from particles traversing the separation region of the impactor. The collection efficiency of the major flow was measured on an individual-particle basis for bulk Stokes numbers ranging from 0.42 to 25. We present an analysis based upon the local Stokes number to explain the transmission frequency of particles significantly larger than the 50% cutoff diameter into the major flow. The transmission efficiency calculated from the local Stokes number exhibits good agreement with the measured collection efficiencies.

Visualization of Defect Particle Transmission to the Major Flow of a Slit Virtual Impactor

Wave packets in a system governed by a Hamiltonian with a generic nonlinear spectrum typically exhibit both full and fractional revivals. It is shown that, by varying the parameters in the Hamiltonian cyclically with a period T and thus inducing suitable geometric phases in the states, fractional revivals can be eliminated at the relevant times T,&nbsp;2T,... . Further, with the introduction of this time step T, the occurrence of near full revivals can be mapped onto that of Poincaré recurrences in an irrational rotation map of the circle. The distinctive recurrence statistics of the latter can thus serve as a clear signature of the dynamics of wave packet revivals.

Department Of Physics

Journal of Statistical Physics volume

Control of Wave Packet Revivals Using Geometric Phases

A cycle C passing through two specific vertices s and t of a biconnected graph is said to be an st-ambitus if its bridges do not interlace in some special way. We present algorithms for st-ambitus for planar biconnected graphs, which are much simpler than the one known for general graphs [MT]. Our algorithm runs in O(n) time on a sequential machine and (log n) parallel time using O(n/log n) processors on an EREW PRAM.