2,535 research outputs found
Using Incomplete Information for Complete Weight Annotation of Road Networks -- Extended Version
We are witnessing increasing interests in the effective use of road networks.
For example, to enable effective vehicle routing, weighted-graph models of
transportation networks are used, where the weight of an edge captures some
cost associated with traversing the edge, e.g., greenhouse gas (GHG) emissions
or travel time. It is a precondition to using a graph model for routing that
all edges have weights. Weights that capture travel times and GHG emissions can
be extracted from GPS trajectory data collected from the network. However, GPS
trajectory data typically lack the coverage needed to assign weights to all
edges. This paper formulates and addresses the problem of annotating all edges
in a road network with travel cost based weights from a set of trips in the
network that cover only a small fraction of the edges, each with an associated
ground-truth travel cost. A general framework is proposed to solve the problem.
Specifically, the problem is modeled as a regression problem and solved by
minimizing a judiciously designed objective function that takes into account
the topology of the road network. In particular, the use of weighted PageRank
values of edges is explored for assigning appropriate weights to all edges, and
the property of directional adjacency of edges is also taken into account to
assign weights. Empirical studies with weights capturing travel time and GHG
emissions on two road networks (Skagen, Denmark, and North Jutland, Denmark)
offer insight into the design properties of the proposed techniques and offer
evidence that the techniques are effective.Comment: This is an extended version of "Using Incomplete Information for
Complete Weight Annotation of Road Networks," which is accepted for
publication in IEEE TKD
A study of point discharge current observations in the thunderstorm environment at a tropical station during the year 1987 and 1988
The results of the measurements of point discharge current observations at Pune, India, during years 1987 and 1988 are presented by categorizing and studying their number of spells, polar current average durations, and current magnitudes in day-time and night-time conditions. While the results showed that the thunderstorm activity occupies far more day-time than the night-time the level of current magnitudes remains nearly the same in the two categories
Factorization, Power Corrections, and the Pion Form Factor
This letter is an investigation of the pion form factor utilizing recently
developed effective field theory techniques. The primary results reported are:
Both the transition and electromagnetic form factors are corrected at order
. However, these corrections only arise due to time ordered products
which are sensitive to soft components of the pion. The usual higher twist wave
function corrections contribute only at order , when the quark
mass vanishes. In the case of the electromagnetic form factor the
power correction is enhanced by a power of relative to the
leading order result of Brodsky and Lepage, if the scale is
non-perturbative. This enhanced correction could explain the discrepancy with
the data.Comment: Published, extended, versio
Pion Interactions in the X(3872)
We consider pion interactions in an effective field theory of the narrow
resonance X(3872), assuming it is a weakly bound molecule of the charm mesons
D^{0} \bar D^{*0} and D^{*0} \bar D^{0}. Since the hyperfine splitting of the
D^{0} and D^{*0} is only 7 MeV greater than the neutral pion mass, pions can be
produced near threshold and are non-relativistic. We show that pion exchange
can be treated in perturbation theory and calculate the next-to-leading-order
correction to the partial decay width \Gamma[X \to D^0 \bar D^{0} \pi^0].Comment: 26 pages, 11 figures, revtex4, to appear in Phys. Rev.
Dynamical Polarizabilities of SU(3) Octet of Baryons
We present calculations and an analysis of the spin-independent dipole
electric and magnetic dynamical polarizabilities for the lowest in mass SU(3)
octet of baryons. These extensive calculations are made possible by the recent
implementation of semi-automatized calculations in Chiral Perturbation Theory
which allows evaluating dynamical spin-independent electromagnetic
polarizabilities from Compton scattering up to next-to-the-leading order. Our
results are in good agreement with calculations performed for nucleons found in
the literature. The dependencies for the range of photon energies up to 1 GeV,
covering the majority of the meson photo production channels, are analyzed. The
separate contributions into polarizabilities from the various baryon meson
clouds are studied.Comment: 10 pages, 7 figures, extended analysis of hyperon polarizabilitie
- …