17,952 research outputs found
Investigating Fatigue Performance on the Foamed Asphalt Specimens Generated Using Different Foam Properties
An evaluation of fatigue resistance for foamed asphalt mixture is very demanding since the binder is not continuously distributed on the aggregate surface and this mixtures contains water, the content of which dramatically affects the mechanical properties. This paper discusses the results of laboratory fatigue testingon the foamed asphalt mixtures in which the specimens are generated using three different foamed bitumen properties. Foamed bitumen as the binder was produced at three different foaming water content (FWC) at a temperature of 180oC using a 70/100 pen. The aggregates were mechanically mixed with foamed bitumen using a Hobart mixer. The resulting mixtures were then compacted using a gyratory compactor to generatespecimen with diameter of 100 mm. The specimens were fatigue tested at various stress levels at a temperature of 20oC following a curing period of 3 days at 40oC. Overall, fatigue performance of foamed asphalt can be identified based upon both stress and strain for mixtures produced at FWC 1%, 5%, and 10%
Stellar population gradients in Seyfert 2 galaxies. Northern sample
We use high signal-to-noise ratio long-slit spectra in the 3600-4700A range
of the twenty brightest northern Seyfert 2 galaxies to study the variation of
the stellar population properties as a function of distance from the nucleus.
In order to characterize the stellar population and other continuum sources
(e.g. featureless continuum FC) we have measured equivalent widths Ws of six
absorption features, four continuum colours and their radial variations, and
performed spectral population synthesis as a function of distance from the
nucleus. About half the sample has CaIIK and G-band W values smaller at the
nucleus than at 1 kpc from it, due to a younger population and/or FC. The
stellar population synthesis shows that, while at the nucleus, 75% of the
galaxies present contribution > 20% of ages younger or equal than 100Myr and/or
of a FC, this proportion decreases to 45% at 3 kpc. In particular, 55% of the
galaxies have contribution > 10% of the 3 Myr/FC component (a degenerate
component in which one cannot separate what is due to a FC or to a 3 Myr
stellar population) at the nucleus, but only 25% of them have this contribution
at 3 kpc. As reference, the stellar population of 10 non-Seyfert galaxies,
spanning the Hubble types of the Seyfert (from S0 to Sc) was also studied. A
comparison between the stellar population of the Seyferts and that of the
non-Seyferts shows systematic differences: the contribution of ages younger
than 1 Gyr is in most cases larger in the Seyfert galaxies than in
non-Seyferts, not only at the nucleus but up to 1 kpc from it.Comment: 23 pages, 18 figures, MNRAS in pres
Equivariant Poincar\'e series of filtrations and topology
Earlier, for an action of a finite group on a germ of an analytic
variety, an equivariant -Poincar\'e series of a multi-index filtration in
the ring of germs of functions on the variety was defined as an element of the
Grothendieck ring of -sets with an additional structure. We discuss to which
extend the -Poincar\'e series of a filtration defined by a set of curve or
divisorial valuations on the ring of germs of analytic functions in two
variables determines the (equivariant) topology of the curve or of the set of
divisors
Local Unitary Quantum Cellular Automata
In this paper we present a quantization of Cellular Automata. Our formalism
is based on a lattice of qudits, and an update rule consisting of local unitary
operators that commute with their own lattice translations. One purpose of this
model is to act as a theoretical model of quantum computation, similar to the
quantum circuit model. It is also shown to be an appropriate abstraction for
space-homogeneous quantum phenomena, such as quantum lattice gases, spin chains
and others. Some results that show the benefits of basing the model on local
unitary operators are shown: universality, strong connections to the circuit
model, simple implementation on quantum hardware, and a wealth of applications.Comment: To appear in Physical Review
Black hole evaporation with separated fermions
In models with a low quantum gravity scale, a well-motivated reason to expect
quark and lepton fields are localized but physically separated is to avoid
proton decay. This could happen in a ``fat-brane'' or in an additional,
orthogonal 1/TeV sized dimension in which the gauge and Higgs fields live
throughout. Black holes with masses of order the quantum gravity scale are
therefore expected to evaporate non-universally, preferentially radiating
directly into quarks or leptons but not both. Should black holes be copiously
produced at a future hadron collider, we find the ratio of final state jets to
charged leptons to photons is 113:8:1, which differs from previous analyses
that assumed all standard model fields live at the same point in the extra
dimensional space.Comment: 5 pages, REVTe
NIR spectroscopy of the Sun and HD20010 - Compiling a new linelist in the NIR
Context: Effective temperature, surface gravity, and metallicity are basic
spectroscopic stellar parameters necessary to characterize a star or a
planetary system. Reliable atmospheric parameters for FGK stars have been
obtained mostly from methods that relay on high resolution and high
signal-to-noise optical spectroscopy. The advent of a new generation of high
resolution near-IR spectrographs opens the possibility of using classic
spectroscopic methods with high resolution and high signal-to-noise in the NIR
spectral window. Aims: We aim to compile a new iron line list in the NIR from a
solar spectrum to derive precise stellar atmospheric parameters, comparable to
the ones already obtained from high resolution optical spectra. The spectral
range covers 10 000 {\AA} to 25 000 {\AA}, which is equivalent to the Y, J, H,
and K bands. Methods: Our spectroscopic analysis is based on the iron
excitation and ionization balance done in LTE. We use a high resolution and
high signal-to-noise ratio spectrum of the Sun from the Kitt Peak telescope as
a starting point to compile the iron line list. The oscillator strengths (log
gf) of the iron lines were calibrated for the Sun. The abundance analysis was
done using the MOOG code after measuring equivalent widths of 357 solar iron
lines. Results: We successfully derived stellar atmospheric parameters for the
Sun. Furthermore, we analysed HD20010, a F8IV star, from which we derived
stellar atmospheric parameters using the same line list as for the Sun. The
spectrum was obtained from the CRIRES- POP database. The results are compatible
with the ones found in the literature, confirming the reliability of our line
list. However, due to the quality of the data we obtain large errors.Comment: 9 pages and 9 figure
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