19,301 research outputs found
Two-Site Quantum Random Walk
We study the measure theory of a two-site quantum random walk. The truncated
decoherence functional defines a quantum measure on the space of
-paths, and the in turn induce a quantum measure on the
cylinder sets within the space of untruncated paths. Although
cannot be extended to a continuous quantum measure on the full -algebra
generated by the cylinder sets, an important question is whether it can be
extended to sufficiently many physically relevant subsets of in a
systematic way. We begin an investigation of this problem by showing that
can be extended to a quantum measure on a "quadratic algebra" of subsets of
that properly contains the cylinder sets. We also present a new
characterization of the quantum integral on the -path space.Comment: 28 page
The Pawns of War: A Personal Account of the Attack on VerrĂšres Ridge by The South Saskatchewan Regiment, 20 July 1944
A number of current books deal with Operations Goodwood and Atlantic, but scant attention has been paid to the 6th Canadian Infantry Brigade and its three regiments, the Queenâs Own Cameron Highlanders of Canada (CAM), the Fusiliers Mont-Royal (FMR) and the South Saskatchewan Regiment (SSR), and to the Essex Scottish Regiment which was attached to 6th Brigade during this operation. When our role has been discussed at all, historians have inferred that the SSR fled or withdrew in panic in this action. My role was as Commander âBâ Company of the SSR, and later as Acting Commanding Officer (A/CO) of the SSR during this operation. I wish to record my memories of the battle supplemented by historical documentation which I hope will cause historians to review the 6th Brigade action of 20 July 1944
Orthogonal frequency-division multiplexing in wireless communication systems with multimode fiber feeds
The feasibility of using multimode fiber as an inexpensive
cell feed in broad-band indoor picocellular systems is investigated in this paper. The performance of coded orthogonal frequency-division multiplexing (OFDM) for a variety of multimode fiber profiles, including stepped index and -profile graded index fibers, is assessed. In addition to its ability to perform well in a frequency-
selective multipath environment, OFDM is shown to offer
good protection against the frequency selectivity of a dispersive multimode fiber. Data rates in excess of 100 Mb/s (without equalization) over a multimode fiber channel are possible, whereas they may be limited to some 20â30 Mb/s using conventional ASK modulation
Characteristic Angles in the Wetting of an Angular Region: Deposit Growth
As was shown in an earlier paper [1], solids dispersed in a drying drop
migrate to the (pinned) contact line. This migration is caused by outward flows
driven by the loss of the solvent due to evaporation and by geometrical
constraint that the drop maintains an equilibrium surface shape with a fixed
boundary. Here, in continuation of our earlier paper [2], we theoretically
investigate the evaporation rate, the flow field and the rate of growth of the
deposit patterns in a drop over an angular sector on a plane substrate.
Asymptotic power laws near the vertex (as distance to the vertex goes to zero)
are obtained. A hydrodynamic model of fluid flow near the singularity of the
vertex is developed and the velocity field is obtained. The rate of the deposit
growth near the contact line is found in two time regimes. The deposited mass
falls off as a weak power Gamma of distance close to the vertex and as a
stronger power Beta of distance further from the vertex. The power Gamma
depends only slightly on the opening angle Alpha and stays between roughly -1/3
and 0. The power Beta varies from -1 to 0 as the opening angle increases from 0
to 180 degrees. At a given distance from the vertex, the deposited mass grows
faster and faster with time, with the greatest increase in the growth rate
occurring at the early stages of the drying process.Comment: v1: 36 pages, 21 figures, LaTeX; submitted to Physical Review E; v2:
minor additions to Abstract and Introductio
A State Space Framework for Automatic Forecasting Using Exponential Smoothing Methods.
We provide a new approach to automatic business forecasting based on an extended range of exponential smoothing methods. Each method in our taxonomy of exponential smoothing methods can be shown to be equivalent to the forecasts obtained from a state space model. This allows (1) the easy calculation of the likelihood, the AIC and other model selection criteria; (2) the computation of prediction intervals for each method; and (3) random simulation from the underlying state space model. We demonstrate the methods by applying them to the data from the M-competition on the M3-competition.Automatic forecasting, exponential smoothing, prediction intervals, state space models.
Aspects of Axion Phenomenology in a slice of AdS_5
Motivated by multi-throat considerations, we study the phenomenological
implications of a bulk axion in a slice of AdS_5 with a large extra dimension:
k~0.01 eV, kR > 1. In particular, we compare axion physics with a warped
geometry to axions in flat compactifications. As in flat compactification
scenarios, we find that the mass of the axion can become independent from the
underlying Peccei-Quinn scale. Surprisingly, we find that in warped extra
dimensions the axion's invisibility, cosmological viability, and basic
phenomenology remain essentially unaltered in comparison to axions in flat
compactifications.Comment: 25 pages, 9 figure
Minimal speed of fronts of reaction-convection-diffusion equations
We study the minimal speed of propagating fronts of convection reaction
diffusion equations of the form for
positive reaction terms with . The function is continuous
and vanishes at . A variational principle for the minimal speed of the
waves is constructed from which upper and lower bounds are obtained. This
permits the a priori assesment of the effect of the convective term on the
minimal speed of the traveling fronts. If the convective term is not strong
enough, it produces no effect on the minimal speed of the fronts. We show that
if , then the minimal speed is given by
the linear value , and the convective term has no effect on the
minimal speed. The results are illustrated by applying them to the exactly
solvable case . Results are also given for
the density dependent diffusion case .Comment: revised, new results adde
Axion-photon Couplings in Invisible Axion Models
We reexamine the axion-photon couplings in various invisible axion models
motivated by the recent proposal of using optical interferometry at the ASST
facility in the SSCL to search for axion. We illustrate that the assignment of
charges for the fermion fields plays an important role in
determining the couplings. Several simple non-minimal invisible axion models
with suppressed and enhanced axion-photon couplings are constructed,
respectively. We also discuss the implications of possible new experiments to
detect solar axions by conversion to -rays in a static magnetic apparatus
tracking the sun.Comment: 14 pages, LaTeX fil
Studies of Mass and Size Effects in Three-Dimensional Vibrofluidized Granular Mixtures
We examine the steady state properties of binary systems of driven inelastic
hard spheres. The spheres, which move under the influence of gravity, are
contained in a vertical cylinder with a vibrating base. We computed the
trajectories of the spheres using an event-driven molecular dynamics algorithm.
In the first part of the study, we chose simulation parameters that match those
of experiments performed by Wildman and Parker. Various properties computed
from the simulation including the density profile, granular temperature and
circulation pattern are in good qualitative agreement with the experiments. We
then studied the effect of varying the mass ratio and the size ratio
independently while holding the other parameters constant. The mass and size
ratio are shown to affect the distribution of the energy. The changes in the
energy distributions affect the packing fraction and temperature of each
component. The temperature of the heavier component has a non-linear dependence
on the mass of the lighter component, while the temperature of the lighter
component is approximately proportional to its mass. The temperature of both
components is inversely dependent on the size of the smaller component.Comment: 14 Pages, 12 Figures, RevTeX
- âŠ