59 research outputs found
Multi-Object Tracking with Interacting Vehicles and Road Map Information
In many applications, tracking of multiple objects is crucial for a
perception of the current environment. Most of the present multi-object
tracking algorithms assume that objects move independently regarding other
dynamic objects as well as the static environment. Since in many traffic
situations objects interact with each other and in addition there are
restrictions due to drivable areas, the assumption of an independent object
motion is not fulfilled. This paper proposes an approach adapting a
multi-object tracking system to model interaction between vehicles, and the
current road geometry. Therefore, the prediction step of a Labeled
Multi-Bernoulli filter is extended to facilitate modeling interaction between
objects using the Intelligent Driver Model. Furthermore, to consider road map
information, an approximation of a highly precise road map is used. The results
show that in scenarios where the assumption of a standard motion model is
violated, the tracking system adapted with the proposed method achieves higher
accuracy and robustness in its track estimations
The Phase Diagram for Wess-Zumino Models
Dynamical supersymmetry breaking is an important issue for applications of
supersymmetry in particle physics. The functional renormalization group
equations allow for a nonperturbative approach that leaves supersymmetry
intact. Therefore they offer a promising tool to investigate dynamical
supersymmetry breaking. Here we will employ this method to derive the phase
diagram and a surprisingly rich RG fixed-point structure with corresponding
critical exponents for the Wess-Zumino model in two dimensions.Comment: 4 pages, 4 figures, talk given at SUSY09, Boston, MA, 5-10 June 2009,
to appear in the proceeding
A functional perspective on emergent supersymmetry
We investigate the emergence of supersymmetry in the long-range
behavior of three-dimensional parity-symmetric Yukawa systems. We discuss a
renormalization approach that manifestly preserves supersymmetry whenever such
symmetry is realized, and use it to prove that supersymmetry-breaking operators
are irrelevant, thus proving that such operators are suppressed in the
infrared. All our findings are illustrated with the aid of the
-expansion and a functional variant of perturbation theory, but we
provide numerical estimates of critical exponents that are based on the
non-perturbative functional renormalization group.Comment: 28 pages, 2 figures; v2: published version, includes a new appendi
Supersymmetry breaking as a quantum phase transition
We explore supersymmetry breaking in the light of a rich fixed-point
structure of two-dimensional supersymmetric Wess-Zumino models with one
supercharge using the functional renormalization group (RG). We relate the
dynamical breaking of supersymmetry to an RG relevant control parameter of the
superpotential which is a common relevant direction of all fixed points of the
system. Supersymmetry breaking can thus be understood as a quantum phase
transition analogously to similar transitions in correlated fermion systems.
Supersymmetry gives rise to a new superscaling relation between the critical
exponent associated with the control parameter and the anomalous dimension of
the field -- a scaling relation which is not known in standard spin systems.Comment: 5 pages, 2 figures, discussion of results extended, version to appear
as a Rapid Communication in Phys. Rev.
Environment Perception Framework Fusing Multi-Object Tracking, Dynamic Occupancy Grid Maps and Digital Maps
Autonomously driving vehicles require a complete and robust perception of the
local environment. A main challenge is to perceive any other road users, where
multi-object tracking or occupancy grid maps are commonly used. The presented
approach combines both methods to compensate false positives and receive a
complementary environment perception. Therefore, an environment perception
framework is introduced that defines a common representation, extracts objects
from a dynamic occupancy grid map and fuses them with tracks of a Labeled
Multi-Bernoulli filter. Finally, a confidence value is developed, that
validates object estimates using different constraints regarding physical
possibilities, method specific characteristics and contextual information from
a digital map. Experimental results with real world data highlight the
robustness and significance of the presented fusing approach, utilizing the
confidence value in rural and urban scenarios
Flow Equation for Supersymmetric Quantum Mechanics
We study supersymmetric quantum mechanics with the functional RG formulated
in terms of an exact and manifestly off-shell supersymmetric flow equation for
the effective action. We solve the flow equation nonperturbatively in a
systematic super-covariant derivative expansion and concentrate on systems with
unbroken supersymmetry. Already at next-to-leading order, the energy of the
first excited state for convex potentials is accurately determined within a 1%
error for a wide range of couplings including deeply nonperturbative regimes.Comment: 24 pages, 8 figures, references added, typos correcte
Low dose effects and non-monotonic dose responses for endocrine active chemicals: Science to practice workshop: Workshop summary
A workshop was held in Berlin September 12-14th 2012 to assess the state of the science of the data supporting low dose effects and non-monotonic dose responses (“low dose hypothesis”) for chemicals with endocrine activity (endocrine disrupting chemicals or EDCs). This workshop consisted of lectures to present the current state of the science of EDC action and also the risk assessment process. These lectures were followed by breakout sessions to integrate scientists from various backgrounds to discuss in an open and unbiased manner the data supporting the “low dose hypothesis”. While no consensus was reached the robust discussions were helpful to inform both basic scientists and risk assessors on all the issues. There were a number of important ideas developed to help continue the discussion and improve communication over the next few years.JRC.I.5-Systems Toxicolog
Deconstructing Non-Abelian Gauge Theories at One Loop
Deconstruction of 5D Yang-Mills gauge theories is studied in next-to-leading
order accuracy. We calculate one-loop corrections to the mass spectrum of the
non-linear gauged sigma-model, which is the low energy effective theory of the
deconstructed theory. Renormalization is carried out following the standard
procedure of effective field theories. The relation between the radius of the
compactified fifth dimension and the symmetry breaking scale of the non-linear
sigma-model is modified by radiative corrections. We demonstrate that one can
match the low lying spectrum of the gauge boson masses of the effective 4D
gauged non-linear sigma-model to the Kaluza-Klein modes of the 5D theory at
one-loop accuracy
A Spectroscopic Study of Mass Outflows in the Interacting Binary RY Scuti
The massive interacting binary RY Scuti is an important representative of an
active mass-transferring system that is changing before our eyes and which may
be an example of the formation of a Wolf-Rayet star through tidal stripping.
Utilizing new and previously published spectra, we present examples of how a
number of illustrative absorption and emission features vary during the binary
orbit. We identify spectral features associated with each component, calculate
a new, double-lined spectroscopic binary orbit, and find masses of 7.1 +/- 1.2
M_sun for the bright supergiant and 30.0 +/- 2.1 M_sun for the hidden massive
companion. Through tomographic reconstruction of the component spectra from the
composite spectra, we confirm the O9.7 Ibpe spectral class of the bright
supergiant and discover a B0.5 I spectrum associated with the hidden massive
companion; however, we suggest that the latter is actually the spectrum of the
photosphere of the accretion torus immediately surrounding the massive
companion. We describe the complex nature of the mass loss flows from the
system in the context of recent hydrodynamical models for beta Lyr, leading us
to conclude RY Scuti has matter leaving the system in two ways: 1) a bipolar
outflow from winds generated by the hidden massive companion, and 2) mass from
the bright O9.7 Ibpe supergiant flowing from the region near the L2 point to
fill out a large, dense circumbinary disk. This circumbinary disk (radius ~ 1
AU) may feed the surrounding double-toroidal nebula (radius ~ 2000 AU).Comment: 41 pages with 7 tables and 11 figures, accepted to Ap
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