32,222 research outputs found
On the double-mode RR Lyrae variables of the Sculptor dwarf galaxy
Frequency analysis of more than 300 stars of the OGLE database on Sculptor
galaxy has led to the discovery of 18 double-mode RR Lyrae (RRd) variables.
This yields a 20% incidence rate for double-mode pulsation among the variables
previously classified as first overtone RR Lyrae stars in this galaxy. Most of
the RRd stars cover the period range of 0.47d < P_0 < 0.49d but there are two
stars with longer periods of ~0.54d. All variables fit well in the pattern of
the P_0 --> P_1/P_0 diagram, spanned by the RRd stars of the Galactic globular
clusters and those of the Large Magellanic Cloud (LMC). It follows from our
previous investigations that the luminosities and masses of the RRd stars in
Galactic globular clusters and in the LMC are almost independent of
metallicity. By assuming that the Sculptor RRd variables also obey this rule,
with the aid of the pulsation equations we estimate their metallicities. For
most of the stars we get [Fe/H]~ -1.5, which is the same value as that obtained
from a semi-empirical method for the average metallicity of the fundamental
mode (RRab) stars. Two RRd stars have considerably lower metallicities, but
even those are within the range corresponding to the RRab stars. The narrower
metallicity range of the RRd stars is in agreement with their observed
luminosity range, which is about three times smaller than that of the RRab
stars.Comment: 7 pages, 5 figures, 2 tables, accepted in Astronomy & Astrophysic
Analytic solution of Guyer-Krumhansl equation for laser flash experiments
The existence of non-Fourier heat conduction is known for a long time in
small and low temperature systems. The deviation from Fourier's law has been
found at room temperature in heterogeneous materials like rocks and metal foams
\cite{Botetal16, Vanetal17}. These experiments emphasized that the so-called
Guyer-Krumhansl equation is adequate for modeling complex materials. In this
paper an analytic solution of Guyer-Krumhansl equation is presented considering
boundary conditions from laser flash experiment. The solutions are validated
with the help of a numerical code \cite{KovVan15} developed for generalized
heat equations
Evaluating Enterprize Delivery Using the TYPUS Metrics and the KILT Mode
The goal of this work is the technical, ecological, environmental and social examination of the life-cycle (LC) of any product (consumable, service, production) using the TYPUS metrics and the KILT model. The life-cycle starts when the idea of a product is born and lasts until complete dismissal through design, implementation and operation, etc. In the first phases requirements’ specification, analysis, several design steps (global plan, detailed design, assembly design, etc.) are followed by part manufacturing, assembly, testing, diagnostics and operation, advertisement, service, maintenance, etc. Then finally disassembly and dismissal are coming, but dismissal can be substituted by re-cycling (e.g. melting the metals) or re-use (used parts applications). Qualitative and quantitative evaluations of enterprise results are supported by the new models and metrics
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