279 research outputs found
The role of language skills in interactive social book search sessions
When searching for books, people frequently have to deal with content that is in a language different from their own. However, research on multilingual systems has generally focused on the user interface's language rather than the content language. In this paper, we describe and compare early results from the multilingual aspects in the Interactive Social Book Search (iSBS) task at CLEF 2014 and 2015. A preliminary analysis of usage patterns for native English and non-native English speakers indicates an influence of language skills on search behaviour during goal-oriented and casual leisure tasks. Based on previous experiences and results, strengths and challenges of IIR studies are discussed
Surface Influence on Flux Penetration into HTS Bulks
The influence of surface treatment on AC loss in melt-processed quasi-single
crystal HTS was investigated with resonance oscillations technique. We have
found that amplitude dependencies of AC loss on magnetic field amplitude become
rather complicated after surface polishing. The experimental data show well
distinguished dynamic crossover from absence of barrier at low rates of field
variation to its appearence at higher rates. An explaination of such a dynamic
surface barrier appearance based on consideration of along surface vortex
propagation was suggested.Comment: 2 pages with 1 EPS figure, to be presented at LT2
Simple technique for superconducting joints quality estimation in bulk melt-processed high temperature superconductors
We propose an empirical approach to estimate the quality of superconducting
joints (welds) between blocks of bulk high temperature superconductors (HTS).
As a measuring value, we introduce a joint's quality factor and show its
natural correlation with joint's critical current density. Being simple and
non-destructive, this approach is considered to be quite important to solve the
problem of utilization of HTS in large scale applications. The approach has
been applied to characterize the joint's quality of melt-processed Y-123 joined
by Tm-123 solder.Comment: 3 pages with 2 figures (revtex
Determination of critical current density in melt-processed HTS bulks from levitation force measurements
A simple approach to describe the levitation force measurements on
melt-processed HTS bulks was developed. A couple of methods to determine the
critical current density were introduced. The averaged -plane
values for the field parallel to this plane were determined. The first and
second levitation force hysteresis loops calculated with these values
coincide remarkably well with the experimental data.Comment: 10 pages (tex), 2 figures (in jpeg
Magnetic Flux Dynamics in HTS Bulks with Levitation Techniques
The discovery of high-temperature superconductors (HTS) has led to understanding that, in order to explain and utilize the phenomenon, completely new physical approaches should be introduced at all scales: microscopic, mesoscopic, macroscopic. Leaving first two scales beyond the scope of the present paper, we focus in the upper limit of the last scale, the study of the magnetic flux dynamics in HTS bulks—the dynamics of the ‘compact vortex structures’. A new direction in the experimental superconducting physics, the investigation of HTS bulks with levitation techniques, which has been elaborated during last years to effectively explore the subject, as well as the new fundamental and applied results obtained there from are overviewed here.Відкриття високотемпературних надпровідників (ВТНП) призвело до розуміння того, що задля пояснення та використання цього явища на всіх рівнях: мікроскопічному, мезоскопічному та макроскопічному, має бути створено принципово нові фізичні підходи. Полишаючи перші два рівні поза увагою даної роботи, ми детально розглядаємо верхню границю останнього — дослідження динаміки магнітного потоку в масивних ВТНП, динаміки «компактових вихорових структур». Дана робота — це огляд нового напрямку експериментальної фізики надпровідників — дослідження масивних ВТНП левітаційними методами — що його було вироблено останнім часом для вивчення зазначеної проблеми, а також тих нових фундаментальних та практичних результатів, що було тут отриманоОткрытие высокотемпературных сверхпроводников (ВТСП) привело к пониманию того, что для объяснения и использования этого явления необходимо создание принципиально новых физических подходов на всех уровнях: микроскопическом, мезоскопическом, макроскопическом. Оставляя первые два уровня за рамками данной работы, мы сфокусировали внимание на верхнем пределе последнего — исследовании динамики магнитного потока в массивных ВТСП, динамики «компактных вихревых структур». Данная работа — это обзор нового направления экспериментальной физики сверхпроводников, которое было выработано за последние годы, а также тех новых фундаментальных и прикладных результатов, которые были здесь получены
Electronic structure and magneto-optical Kerr effect in the compound UCuP₂
The optical and magneto-optical (MO) spectra of the fernary compound UCuP₂ are investigated from first principles, using the fully relativistic Dirac linear-muffin-tin-orbital band structure method and density-functional theory in the local spin-density approximation. Within a band-like description of the 5f electrons, good agreement with the measured MO spectra is obtained. The origin of the Kerr rotation in the compound is examined
Peculiarities of phonon spectra and lattice heat capacity in Ir and Rh
A simple pseudopotential model is proposed, which allows the phonon spectra
and temperature dependence of the lattice heat capacity of Ir and Rh be
described with a high enough accuracy. A careful comparison of the calculated
and experimental values of the lattice heat capacity is carried out, with the
procedure of the identification of the phonon contribution to the heat capacity
and determination of the characteristics (momenta) of the phonon density of
states from the experimental values of the total heat capacity of metal at a
constant pressure being described in detail. The results of the theoretical
calculations explain, in particular, such peculiar feature of Ir and Rh,
unusual for cubic metals, as a sharp (more than by a factor of 1.5) decrease in
the effective Debye temperature with increasing termperature. The temperature
dependence of the mean square amplitude of atomic displacements in Ir and Rh
has been calculated. Basing on the band calculations the manifestation of the
Kohn singularities in the phonon spectra of Ir are discussed.Comment: 15 pages, LaTeX2e, 12 figures in postscrip
Reduced Bloch mode expansion for periodic media band structure calculations
Reduced Bloch mode expansion is presented for fast periodic media band
structure calculations. The expansion employs a natural basis composed of a
selected reduced set of Bloch eigenfunctions. The reduced basis is selected
within the irreducible Brillouin zone at high symmetry points determined by the
medium's crystal structure and group theory (and possibly at additional related
points). At each of the reciprocal lattice selection points, a number of Bloch
eigenfunctions are selected up to the frequency range of interest for the band
structure calculations. Since it is common to initially discretize the periodic
unit cell and solution field using some choice of basis, reduced Bloch mode
expansion is practically a secondary expansion that uses a selected set of
Bloch eigenvectors. Such expansion therefore keeps, and builds on, any
favorable attributes a primary expansion approach might exhibit. Being in line
with the well known concept of modal analysis, the proposed approach maintains
accuracy while reducing the computation time by up to two orders of magnitudes
or more depending on the size and extent of the calculations. Results are
presented for phononic, photonic and electronic band structures.Comment: 15 pages of text, 8 figures, submitted for journal publication, minor
edits and correction of typo
Born Effective Charges of Barium Titanate: band by band decomposition and sensitivity to structural features
The Born effective charge tensors of Barium Titanate have been calculated for
each of its 4 phases. Large effective charges of Ti and O, also predicted by
shell model calculations and made plausible by a simplified model, reflect the
partial covalent character of the chemical bond. A band by band decomposition
confirms that orbital hybridization is not restricted to Ti and O atoms but
also involves Ba which appears more covalent than generally assumed. Our
calculations reveal a strong dependence of the effective charges on the atomic
positions contrasting with a relative insensitivity on isotropic volume
changes.Comment: 13 page
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