3,506 research outputs found
Focal region fields of distorted reflectors
The problem of the focal region fields scattered by an arbitrary surface reflector under uniform plane wave illumination is solved. The physical optics (PO) approximation is used to calculate the current induced on the reflector. The surface of the reflector is described by a number of triangular domain-wise 5th degree bivariate polynomials. A 2-dimensional Gaussian quadrature is employed to numerically evaluate the integral expressions of the scattered fields. No Freshnel or Fraunhofer zone approximations are made. The relation of the focal fields problem to surface compensation techniques and other applications are mentioned. Several examples of distorted parabolic reflectors are presented. The computer code developed is included, together with instructions on its usage
Teleportation, Braid Group and Temperley--Lieb Algebra
We explore algebraic and topological structures underlying the quantum
teleportation phenomena by applying the braid group and Temperley--Lieb
algebra. We realize the braid teleportation configuration, teleportation
swapping and virtual braid representation in the standard description of the
teleportation. We devise diagrammatic rules for quantum circuits involving
maximally entangled states and apply them to three sorts of descriptions of the
teleportation: the transfer operator, quantum measurements and characteristic
equations, and further propose the Temperley--Lieb algebra under local unitary
transformations to be a mathematical structure underlying the teleportation. We
compare our diagrammatical approach with two known recipes to the quantum
information flow: the teleportation topology and strongly compact closed
category, in order to explain our diagrammatic rules to be a natural
diagrammatic language for the teleportation.Comment: 33 pages, 19 figures, latex. The present article is a short version
of the preprint, quant-ph/0601050, which includes details of calculation,
more topics such as topological diagrammatical operations and entanglement
swapping, and calls the Temperley--Lieb category for the collection of all
the Temperley--Lieb algebra with physical operations like local unitary
transformation
Differential Cross Sections for Higgs Production
We review recent theoretical progress in evaluating higher order QCD
corrections to Higgs boson differential distributions at hadron-hadron
colliders
Landscape statistics of the p-spin Ising model
The statistical properties of the local optima (metastable states) of the
infinite range Ising spin glass with p-spin interactions in the presence of an
external magnetic field h are investigated analytically. The average number of
optima as well as the typical overlap between pairs of identical optima are
calculated for general p. Similarly to the thermodynamic order parameter, for
p>2 and small h the typical overlap q_t is a discontinuous function of the
energy. The size of the jump in q_t increases with p and decreases with h,
vanishing at finite values of the magnetic field.Comment: 12 pages,te
Topology and Evolution of Technology Innovation Networks
The web of relations linking technological innovation can be fairly described
in terms of patent citations. The resulting patent citation network provides a
picture of the large-scale organization of innovations and its time evolution.
Here we study the patterns of change of patents registered by the US Patent and
Trademark Office (USPTO). We show that the scaling behavior exhibited by this
network is consistent with a preferential attachment mechanism together with a
Weibull-shaped aging term. Such attachment kernel is shared by scientific
citation networks, thus indicating an universal type of mechanism linking ideas
and designs and their evolution. The implications for evolutionary theory of
innovation are discussed.Comment: 6 pages, 5 figures, submitted to Physical Review
Properties of Galactic Outflows: Measurements of the Feedback from Star Formation
Properties of starburst-driven outflows in dwarf galaxies are compared to
those in more massive galaxies. Over a factor of roughly 10 in galactic
rotation speed, supershells are shown to lift warm ionized gas out of the disk
at rates up to several times the star formation rate. The amount of mass
escaping the galactic potential, in contrast to the disk, does depend on the
galactic mass. The temperature of the hottest extended \x emission shows little
variation around K, and this gas has enough energy to escape
from the galaxies with rotation speed less than approximately 130 km/s.Comment: 11 pages + 3 figues. Accepted for publication in the Astrophysical
Journa
Annealing schedule from population dynamics
We introduce a dynamical annealing schedule for population-based optimization
algorithms with mutation. On the basis of a statistical mechanics formulation
of the population dynamics, the mutation rate adapts to a value maximizing
expected rewards at each time step. Thereby, the mutation rate is eliminated as
a free parameter from the algorithm.Comment: 6 pages RevTeX, 4 figures PostScript; to be published in Phys. Rev.
POTENT Reconstruction from Mark III Velocities
We present an improved POTENT method for reconstructing the velocity and mass
density fields from radial peculiar velocities, test it with mock catalogs, and
apply it to the Mark III Catalog. Method improvments: (a) inhomogeneous
Malmquist bias is reduced by grouping and corrected in forward or inverse
analyses of inferred distances, (b) the smoothing into a radial velocity field
is optimized to reduce window and sampling biases, (c) the density is derived
from the velocity using an improved nonlinear approximation, and (d) the
computational errors are made negligible. The method is tested and optimized
using mock catalogs based on an N-body simulation that mimics our cosmological
neighborhood, and the remaining errors are evaluated quantitatively. The Mark
III catalog, with ~3300 grouped galaxies, allows a reliable reconstruction with
fixed Gaussian smoothing of 10-12 Mpc/h out to ~60 Mpc/h. We present maps of
the 3D velocity and mass-density fields and the corresponding errors. The
typical systematic and random errors in the density fluctuations inside 40
Mpc/h are \pm 0.13 and \pm 0.18. The recovered mass distribution resembles in
its gross features the galaxy distribution in redshift surveys and the mass
distribution in a similar POTENT analysis of a complementary velocity catalog
(SFI), including the Great Attractor, Perseus-Pisces, and the void in between.
The reconstruction inside ~40 Mpc/h is not affected much by a revised
calibration of the distance indicators (VM2, tailored to match the velocities
from the IRAS 1.2Jy redshift survey). The bulk velocity within the sphere of
radius 50 Mpc/h about the Local Group is V_50=370 \pm 110 km/s (including
systematic errors), and is shown to be mostly generated by external mass
fluctuations. With the VM2 calibration, V_50 is reduced to 305 \pm 110 km/s.Comment: 60 pages, LaTeX, 3 tables and 27 figures incorporated (may print the
most crucial figures only, by commenting out one line in the LaTex source
Harmonic Analysis of Boolean Networks: Determinative Power and Perturbations
Consider a large Boolean network with a feed forward structure. Given a
probability distribution on the inputs, can one find, possibly small,
collections of input nodes that determine the states of most other nodes in the
network? To answer this question, a notion that quantifies the determinative
power of an input over the states of the nodes in the network is needed. We
argue that the mutual information (MI) between a given subset of the inputs X =
{X_1, ..., X_n} of some node i and its associated function f_i(X) quantifies
the determinative power of this set of inputs over node i. We compare the
determinative power of a set of inputs to the sensitivity to perturbations to
these inputs, and find that, maybe surprisingly, an input that has large
sensitivity to perturbations does not necessarily have large determinative
power. However, for unate functions, which play an important role in genetic
regulatory networks, we find a direct relation between MI and sensitivity to
perturbations. As an application of our results, we analyze the large-scale
regulatory network of Escherichia coli. We identify the most determinative
nodes and show that a small subset of those reduces the overall uncertainty of
the network state significantly. Furthermore, the network is found to be
tolerant to perturbations of its inputs
Non-GNSS Smartphone Pedestrian Navigation Using Barometric Elevation and Digital Map-Matching
Pedestrian navigation in outdoor environments where global navigation satellite systems (GNSS) are unavailable is a challenging problem. Existing technologies that have attempted to address this problemoften require external reference signals or specialized hardware, the extra size,weight, power, and cost of which are unsuitable for many applications. This article presents a real-time, self-contained outdoor navigation application that uses only the existing sensors on a smartphone in conjunction with a preloaded digital elevation map. The core algorithm implements a particle filter, which fuses sensor data with a stochastic pedestrian motion model to predict the user’s position. The smartphone’s barometric elevation is then compared with the elevation map to constrain the position estimate. The system developed for this research was deployed on Android smartphones and tested in several terrains using a variety of elevation data sources. The results fromthese experiments showthe systemachieves positioning accuracies in the tens of meters that do not grow as a function of time
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