579 research outputs found
1.3. Sangro Valley and the Five (Paperless) Seasons: Lessons on Building Effective Digital Recording Workflows for Archaeological Fieldwork
Since 2011 the Sangro Valley Project (Italy) has employed a custom-built paperless recording system with iPads and FileMaker at its core. This paper summarizes the evolution of the project’s paperless system and presents lessons learned during five seasons of use (2011–2015) and during the author’s work with two other projects: the Pompeii Archaeological Research Project: Porta Stabia (Italy), and the Say Kah Archaeological Project (Belize). It identifies problems commonly encountered during the implementation of paperless systems and offers recommendations for avoiding or fixing them. Many of these problems are not unique to projects with digital recording systems, and most difficulties were not technical in nature. Rather, many of the most significant problems arose from integrating workflows. Digital recording systems can streamline fieldwork, improve the quality of data collected in the field, significantly reduce errors and misunderstandings, and facilitate new interpretive approaches, but they require thoughtful preparation and implementation.https://dc.uwm.edu/arthist_mobilizingthepast/1004/thumbnail.jp
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http://archive.org/details/graphicenhanceme00motzNAN
On the process of co-deformation and phase dissolution in a hard-soft immiscible Cu Co alloy system during high-pressure torsion deformation
In this study, dual phase CuCo composites with a total immiscibility in the solid state and a very different initial phase strength are deformed by severe plastic deformation. Nanocrystalline supersaturated solid solutions are reached in all CuCo composites independent of the initial composition. The deformation and mechanical mixing process is studied thoroughly by combining scanning electron microscopy, transmission electron microscopy, three-dimensional atom probe tomography and nanoindentation. The indentation hardness of the Cu and Co phase and its evolution as a function of the applied strain is linked to deformation and mechanical mixing process to gain a better understanding how the phase strength mismatch of the Cu and Co phase effects the amount of co-deformation and deformation-induced mixing. Our results show that co-deformation is not a necessary requirement to achieve mechanical mixing
Coherent radiation of an ultra-relativistic charged particle channeled in a periodically bent crystal
We suggest a new type of the undulator radiation which is generated by an
ultra-relativistic particle channeled along a periodically bent
crystallographic plane or axis. The electromagnetic radiation arises mainly due
to the bending of the particle's trajectory, which follows the shape of the
channel. The parameters of this undulator, which totally define the spectrum
and the angular distribution of the radiation (both spontaneous and
stimulated), depend on the type of the crystal and the crystallographic plane
(axis), on the type of a projectile and its energy, and on the shape of the
bent channel, and, thus, can be varied significantly by varying these
characteristics.
As an example, we consider the acoustically induced radiation (AIR) which is
generated by ultra-relativistic particles channeled in a crystal which is bent
by a transverse acoustic wave. The AIR mechanism allows to make the undulator
with the main parameters varying in wide ranges, which are inaccessible in the
undulators based on the motion of particles in the periodic magnetic fields and
also in the field of the laser radiation. The intensity of AIR can be easily
made larger than the intensity of the radiation in a linear crystal and can be
varied in a wide range by varying the frequency and the amplitude of the
acoustic wave in the crystal. A possibility to generate stimulated emission of
high-energy photons (in keV - MeV region) is also discussed.Comment: published in J. Phys. G: Nucl. Part. Phys. 24 (1998) L45-L53,
http://www.iop.or
Photon emission by an ultra-relativistic particle channeling in a periodically bent crystal
This paper is devoted to a detailed analysis of the new type of the undulator
radiation generated by an ultra-relativistic charged particle channeling along
a crystal plane, which is periodically bent by a transverse acoustic wave, as
well as to the conditions limiting the observation of this phenomenon. This
mechanism makes feasible the generation of electromagnetic radiation, both
spontaneous and stimulated, emitted in a wide range of the photon energies,
from X- up to gamma-rays
White dwarf spins from low mass stellar evolution models
The prediction of the spins of the compact remnants is a fundamental goal of
the theory of stellar evolution. Here, we confront the predictions for white
dwarf spins from evolutionary models including rotation with observational
constraints. We perform stellar evolution calculations for stars in the mass
range 1... 3\mso, including the physics of rotation, from the zero age main
sequence into the TP-AGB stage. We calculate two sets of model sequences, with
and without inclusion of magnetic fields. From the final computed models of
each sequence, we deduce the angular momenta and rotational velocities of the
emerging white dwarfs. While models including magnetic torques predict white
dwarf rotational velocities between 2 and 10 km s, those from the
non-magnetic sequences are found to be one to two orders of magnitude larger,
well above empirical upper limits. We find the situation analogous to that in
the neutron star progenitor mass range, and conclude that magnetic torques may
be required in order to understand the slow rotation of compact stellar
remnants in general.Comment: Accepted for A&A Letter
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