1,139 research outputs found
Inhomogeneous Cooling of the Rough Granular Gas in Two Dimensions
We study the inhomogeneous clustered regime of a freely cooling granular gas
of rough particles in two dimensions using large-scale event driven simulations
and scaling arguments. During collisions, rough particles dissipate energy in
both the normal and tangential directions of collision. In the inhomogeneous
regime, translational kinetic energy and the rotational energy decay with time
as power-laws and . We numerically determine
and , independent of the
coefficients of restitution. The inhomogeneous regime of the granular gas has
been argued to be describable by the ballistic aggregation problem, where
particles coalesce on contact. Using scaling arguments, we predict
and for ballistic aggregation, being different from
that obtained for the rough granular gas. Simulations of ballistic aggregation
with rotational degrees of freedom are consistent with these exponents.Comment: 6 pages, 5 figure
Reading habits of students from secondary and higher secondary schools in Patrasayer block of Bankura district, West Bengal, India
This paper has focused on reading habits of school students in Patrasayer block of Bankura district in the state of West Bengal of India. This reading habits include the time spent by the students in school library. We are taken 380 students as sample from nineteen secondary and higher secondary schools at the Patrasayer block. The methodology includes data collection and data analysis. A structured questionnaire has been provided to all 380 students of those nineteen schools. There, lots of parameters have been study and criticized for the purpose of knowing reading habits of the students
Spatial Structures and Giant Number Fluctuations in Models of Active Matter
The large scale fluctuations of the ordered state in active matter systems
are usually characterised by studying the "giant number fluctuations" of
particles in any finite volume, as compared to the expectations from the
central limit theorem. However, in ordering systems, the fluctuations in
density ordering are often captured through their structure functions deviating
from Porod law. In this paper we study the relationship between giant number
fluctuations and structure functions, for different models of active matter as
well as other non-equilibrium systems. A unified picture emerges, with
different models falling in four distinct classes depending on the nature of
their structure functions. For one class, we show that experimentalists may
find Porod law violation, by measuring subleading corrections to the number
fluctuations.Comment: 5 pages, 3 figure
Violation of Porod law in a freely cooling granular gas in one dimension
We study a model of freely cooling inelastic granular gas in one dimension,
with a restitution coefficient which approaches the elastic limit below a
relative velocity scale v. While at early times (t << 1/v) the gas behaves as a
completely inelastic sticky gas conforming to predictions of earlier studies,
at late times (t >> 1/v) it exhibits a new fluctuation dominated phase ordering
state. We find distinct scaling behavior for the (i) density distribution
function, (ii) occupied and empty gap distribution functions, (iii) the density
structure function and (iv) the velocity structure function, as compared to the
completely inelastic sticky gas. The spatial structure functions (iii) and (iv)
violate the Porod law. Within a mean-field approximation, the exponents
describing the structure functions are related to those describing the spatial
gap distribution functions.Comment: 4 pages, 5 figure
Velocity Distribution of Driven Inelastic One-component Maxwell gas
The nature of the velocity distribution of a driven granular gas, though well
studied, is unknown as to whether it is universal or not, and if universal what
it is. We determine the tails of the steady state velocity distribution of a
driven inelastic Maxwell gas, which is a simple model of a granular gas where
the rate of collision between particles is independent of the separation as
well as the relative velocity. We show that the steady state velocity
distribution is non-universal and depends strongly on the nature of driving.
The asymptotic behavior of the velocity distribution are shown to be identical
to that of a non-interacting model where the collisions between particles are
ignored. For diffusive driving, where collisions with the wall are modelled by
an additive noise, the tails of the velocity distribution is universal only if
the noise distribution decays faster than exponential.Comment: 8 pages, 6 figure
Thickness Dependence of the Properties of Magnetron Sputtered Zno : A1 Films and its Application in a-Si:H Thin Film Solar Cell
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