1,923 research outputs found
Queues with superposition arrival processes in heavy traffic
AbstractTo help provide a theoretical basis for approximating queues with superposition arrival processes, we prove limit theorems for the queue-length process in a Σ GIi/G/s model, in which the arrival process is the superposition of n independent and identically distributed stationary renewal processes each with rate n−1. The traffic intensity ρ is allowed to approach the critical value one as n increases. If n(1−ρ)2 → c, 0 < c < ∞, then a limit is obtained that depends on c. The two iterated limits involving ρ and n, which do not agree, are obtained as c → 0 and c → ∞
Large Deviations in Renewal Models of Statistical Mechanics
In Ref. [1] the author has recently established sharp large deviation
principles for cumulative rewards associated with a discrete-time renewal
model, supposing that each renewal involves a broad-sense reward taking values
in a separable Banach space. The renewal model has been there identified with
constrained and non-constrained pinning models of polymers, which amount to
Gibbs changes of measure of a classical renewal process. In this paper we show
that the constrained pinning model is the common mathematical structure to the
Poland-Scheraga model of DNA denaturation and to some relevant one-dimensional
lattice models of Statistical Mechanics, such as the Fisher-Felderhof model of
fluids, the Wako-Sait\^o-Mu\~noz-Eaton model of protein folding, and the
Tokar-Dreyss\'e model of strained epitaxy. Then, in the framework of the
constrained pinning model, we develop an analytical characterization of the
large deviation principles for cumulative rewards corresponding to multivariate
deterministic rewards that are uniquely determined by, and at most of the order
of magnitude of, the time elapsed between consecutive renewals. In particular,
we outline the explicit calculation of the rate functions and successively we
identify the conditions that prevent them from being analytic and that underlie
affine stretches in their graphs. Finally, we apply the general theory to the
number of renewals. From the point of view of Equilibrium Statistical Physics
and Statistical Mechanics, cumulative rewards of the above type are the
extensive observables that enter the thermodynamic description of the system.
The number of renewals, which turns out to be the commonly adopted order
parameter for the Poland-Scheraga model and for also the renewal models of
Statistical Mechanics, is one of these observables
On the area between a L\'evy process with secondary jump inputs and its reflected version
We study the the stochastic properties of the area under some function of the
difference between (i) a spectrally positive L\'evy process that jumps
to a level whenever it hits zero, and (ii) its reflected version .
Remarkably, even though the analysis of each of these processes is challenging,
we succeed in attaining explicit expressions for their difference. The main
result concerns the Laplace-Stieltjes transform of the integral of (a
function of) the distance between and until hits zero.
This result is extended in a number of directions, including the area between
and and a Gaussian limit theorem. We conclude the paper with an
inventory problem for which our results are particularly useful
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