52 research outputs found
Eine Referenzarchitektur für die assistierte und automatisierte Fahrzeugführung mit Fahrereinbindung
Gegenstand der Arbeit ist die Entwicklung einer funktionalen Systemarchitektur, die den Anforderungen des assistierten, teilautomatisierten bis hin zum vollautomatisierten Fahrens gerecht werden soll. Dabei steht insbesondere die Architektur als wissenschaftliche Disziplin im Vordergrund, in der Entscheidungsalternativen erarbeitet und durch Abwägung der sich daraus ergebenden Konsequenzen bewertet und dokumentiert werden.
Im ersten Schritt erfolgt eine Anforderungsanalyse, in der die funktionalen Systemanforderungen in Form notwendiger Fahrmanöver hergeleitet sowie relevante nichtfunktionale Anforderungen (insbes. Test- und Erweiterbarkeit) an die Architektur identifiziert werden. Darauf aufbauend erfolgt die Entwicklung der Referenzarchitektur auf Basis hybrider Robotik-Basisarchitekturen, beginnend mit einer Festlegung des 3-Ebenen Fahrzeugführungsmodelles nach Donges als zugrunde liegendes hierarchisches Abstraktionsmodell. Von besonderer Bedeutung dabei ist das Zusammenspiel zwischen deliberativen Systemelementen zur Zielerreichung einerseits und reaktiven Systemelementen zur schnellen Reaktion auf sich ändernde Situationsparameter andererseits. Als Ergebnis liegt ein hierarchisches Mehrebenensystem mit vier Systemebenen vor. Neben der Festlegung der Kontrollhierarchie wird zusätzlich der Informationsbedarf der Planungsmodule in Richtung des Umfeldmodells skizziert sowie die notwendigen Mensch-Maschine-Schnittstellen zur Fahrereinbindung
The Galactic Mergers and Gravitational Unbound Populations
Motivated by the observations on the intra-cluster light (ICL) and
inter-galactic stellar populations, n-body simulations are used to model the
galactic merging events as a goal to investigate the production and
distribution of gravitational unbound populations (GUPs). Both the parabolic
and hyperbolic mergers are considered and each category includes six models
with different relative orientations between two galaxies. Our results show
that there are more (about a factor of two) GUP after a hyperbolic merging
event than after a parabolic one. In general, depending on the relative
orientation and also the relative velocity of the two galaxies in a merging
pair, a head-on collision of a galaxy pair would only make a tiny fraction
(less than one percent) of the initial stellar mass become luminous GUP but a
considerable fraction (eight to fourteen percent) of the dark matter become
dark GUP.Comment: 29 pages, 14 figures, published in MNRAS, Online Earl
Three-integral multi-component dynamical models and simulations of the nuclear star cluster in NGC 4244
Adaptive optics observations of the flattened nuclear star cluster in the
nearby edge-on spiral galaxy NGC 4244 using the Gemini Near-Infrared Integral
Field Spectrograph (NIFS) have revealed clear rotation. Using these kinematics
plus 2MASS photometry we construct a series of axisymmetric two-component
particle dynamical models with our improved version of NMAGIC, a flexible
Chi^2-made-to-measure code. The models consist of a nuclear cluster disc
embedded within a spheroidal particle population. We find a mass for the
nuclear star cluster of M=1.6^+0.5_-0.2 x 10^7 M_sun within ~42.4 pc (2"). We
also explore the presence of an intermediate mass black hole and show that
models with a black hole as massive as M_bh = 5.0 x 10^5 M_sun are consistent
with the available data. Regardless of whether a black hole is present or not,
the nuclear cluster is vertically anisotropic (beta_z < 0), as was found with
earlier two-integral models. We then use the models as initial conditions for
N-body simulations. These simulations show that the nuclear star cluster is
stable against non-axisymmetric perturbations. We also explore the effect of
the nuclear cluster accreting star clusters at various inclinations. Accretion
of a star cluster with mass 13% that of the nuclear cluster is already enough
to destroy the vertical anisotropy, regardless of orbital inclination.Comment: Replaced with the version accepted for publication in MNRAS. 13
pages, 10 figures, 3 table
Galaxy Assembly Bias on the Red Sequence
Using samples drawn from the Sloan Digital Sky Survey, we study the
relationship between local galaxy density and the properties of galaxies on the
red sequence. After removing the mean dependence of average overdensity (or
"environment") on color and luminosity, we find that there remains a strong
residual trend between luminosity-weighted mean stellar age and environment,
such that galaxies with older stellar populations favor regions of higher
overdensity relative to galaxies of like color and luminosity (and hence of
like stellar mass). Even when excluding galaxies with recent star-formation
activity (i.e., younger mean stellar ages) from the sample, we still find a
highly significant correlation between stellar age and environment at fixed
stellar mass. This residual age-density relation provides direct evidence for
an assembly bias on the red sequence such that galaxies in higher-density
regions formed earlier than galaxies of similar mass in lower-density
environments. We discuss these results in the context of the age-metallicity
degeneracy and in comparison to previous studies at low and intermediate
redshift. Finally, we consider the potential role of assembly bias in
explaining recent results regarding the evolution of post-starburst (or
post-quenching) galaxies and the environmental dependence of the type Ia
supernova rate.Comment: Accepted for publication in MNRA
How do minor mergers promote inside-out growth of ellipticals, transforming the size, density profile and dark matter fraction?
There is observational evidence for inside-out growth of elliptical galaxies
since , which is not driven by in-situ star formation. Many
systems at high redshift have small sizes and surface brightness
profiles with low Sersic indices n. The most likely descendants have, on
average, grown by a factor of two in mass and a factor of four in size,
indicating with . They also have
surface brightness profiles with . This evolution can be
qualitatively explained on the basis of two assumptions: compact ellipticals
predominantly grow by collisionless minor or intermediate 'dry' mergers, and
they are embedded in massive dark matter halos. We draw these conclusions from
idealized collisionless mergers spheroidal galaxies - with and without dark
matter - with mass ratios of 1:1, 1:5, and 1:10. The sizes evolve as with for mass-ratios of 1:1. For minor mergers of
galaxies embedded in dark matter halos, the sizes grow significantly faster and
the profile shapes change more rapidly. Mergers with moderate mass-ratios of
1:5 give and a final Sersic index of after doubling
the stellar mass. This is accompanied by a significant increase of the dark
matter fraction within the stellar half-mass radius, driven by the strong size
increase probing larger, dark matter dominated regions. Only a few intermediate
mass-ratio mergers of galaxies embedded in massive dark matter halos can result
in the observed concurrent inside-out growth and the rapid evolution in profile
shapes. Apart from negative stellar metallicity gradients such a 'minor' merger
scenario also predicts significantly lower dark matter fractions for
compact quiescent galaxies and their rare present day analogues (abbreviated).Comment: accepted for publicatio
EuReCa ONE—27 Nations, ONE Europe, ONE Registry A prospective one month analysis of out-of-hospital cardiac arrest outcomes in 27 countries in Europe
AbstractIntroductionThe aim of the EuReCa ONE study was to determine the incidence, process, and outcome for out of hospital cardiac arrest (OHCA) throughout Europe.MethodsThis was an international, prospective, multi-centre one-month study. Patients who suffered an OHCA during October 2014 who were attended and/or treated by an Emergency Medical Service (EMS) were eligible for inclusion in the study. Data were extracted from national, regional or local registries.ResultsData on 10,682 confirmed OHCAs from 248 regions in 27 countries, covering an estimated population of 174 million. In 7146 (66%) cases, CPR was started by a bystander or by the EMS. The incidence of CPR attempts ranged from 19.0 to 104.0 per 100,000 population per year. 1735 had ROSC on arrival at hospital (25.2%), Overall, 662/6414 (10.3%) in all cases with CPR attempted survived for at least 30 days or to hospital discharge.ConclusionThe results of EuReCa ONE highlight that OHCA is still a major public health problem accounting for a substantial number of deaths in Europe.EuReCa ONE very clearly demonstrates marked differences in the processes for data collection and reported outcomes following OHCA all over Europe. Using these data and analyses, different countries, regions, systems, and concepts can benchmark themselves and may learn from each other to further improve survival following one of our major health care events
Tides in colliding galaxies
Long tails and streams of stars are the most noticeable upshots of galaxy
collisions. Their origin as gravitational, tidal, disturbances has however been
recognized only less than fifty years ago and more than ten years after their
first observations. This Review describes how the idea of galactic tides
emerged, in particular thanks to the advances in numerical simulations, from
the first ones that included tens of particles to the most sophisticated ones
with tens of millions of them and state-of-the-art hydrodynamical
prescriptions. Theoretical aspects pertaining to the formation of tidal tails
are then presented. The third part of the review turns to observations and
underlines the need for collecting deep multi-wavelength data to tackle the
variety of physical processes exhibited by collisional debris. Tidal tails are
not just stellar structures, but turn out to contain all the components usually
found in galactic disks, in particular atomic / molecular gas and dust. They
host star-forming complexes and are able to form star-clusters or even
second-generation dwarf galaxies. The final part of the review discusses what
tidal tails can tell us (or not) about the structure and content of present-day
galaxies, including their dark components, and explains how tidal tails may be
used to probe the past evolution of galaxies and their mass assembly history.
On-going deep wide-field surveys disclose many new low-surface brightness
structures in the nearby Universe, offering great opportunities for attempting
galactic archeology with tidal tails.Comment: 46 pages, 13 figures, Review to be published in "Tidal effects in
Astronomy and Astrophysics", Lecture Notes in Physics. Comments are most
welcom
An investigation in the correlation between Ayurvedic body-constitution and food-taste preference
Eine Referenzarchitektur für die assistierte und automatisierte Fahrzeugführung mit Fahrereinbindung
Gegenstand der Arbeit ist die Entwicklung einer funktionalen Systemarchitektur, die den Anforderungen des assistierten, teilautomatisierten bis hin zum vollautomatisierten Fahrens gerecht werden soll. Dabei steht insbesondere die Architektur als wissenschaftliche Disziplin im Vordergrund, in der Entscheidungsalternativen erarbeitet und durch Abwägung der sich daraus ergebenden Konsequenzen bewertet und dokumentiert werden.
Im ersten Schritt erfolgt eine Anforderungsanalyse, in der die funktionalen Systemanforderungen in Form notwendiger Fahrmanöver hergeleitet sowie relevante nichtfunktionale Anforderungen (insbes. Test- und Erweiterbarkeit) an die Architektur identifiziert werden. Darauf aufbauend erfolgt die Entwicklung der Referenzarchitektur auf Basis hybrider Robotik-Basisarchitekturen, beginnend mit einer Festlegung des 3-Ebenen Fahrzeugführungsmodelles nach Donges als zugrunde liegendes hierarchisches Abstraktionsmodell. Von besonderer Bedeutung dabei ist das Zusammenspiel zwischen deliberativen Systemelementen zur Zielerreichung einerseits und reaktiven Systemelementen zur schnellen Reaktion auf sich ändernde Situationsparameter andererseits. Als Ergebnis liegt ein hierarchisches Mehrebenensystem mit vier Systemebenen vor. Neben der Festlegung der Kontrollhierarchie wird zusätzlich der Informationsbedarf der Planungsmodule in Richtung des Umfeldmodells skizziert sowie die notwendigen Mensch-Maschine-Schnittstellen zur Fahrereinbindung
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