89 research outputs found
Studies on La2-xPrxCayBa2Cu4+yOz (0.1 < x < 0.5) type mixed oxide superconductors
The La2-xPrxCayBa2Cu4+yOz (LaPrCaBCO) mixed oxides have been studied for
their structural and superconducting properties using X-ray diffraction (XRD),
d. c. resistivity, d. c. susceptibility and iodometric double titration. All
the LaPrCaBCO samples for x = 0.1 - 0.5, exhibit tetragonal crystalline
structure with P 4/mmm space group as determined by Rietveld analysis of the
X-ray diffraction data. With increasing x, enhancement in Tc is observed, which
is quite interesting for Pr substituted high Tc oxides. Maximum Tc ~ 58 K has
been observed for x = 0.5(La-2125 stoichiometry). The results of structural
studies and superconducting property measurements are presented in light of
increase in Tc in LaPrCaBCO system with increasing Pr concentration.Comment: 6 pages including 5 figures and 1 tabl
EraseNet: A Recurrent Residual Network for Supervised Document Cleaning
Document denoising is considered one of the most challenging tasks in
computer vision. There exist millions of documents that are still to be
digitized, but problems like document degradation due to natural and man-made
factors make this task very difficult. This paper introduces a supervised
approach for cleaning dirty documents using a new fully convolutional
auto-encoder architecture. This paper focuses on restoring documents with
discrepancies like deformities caused due to aging of a document, creases left
on the pages that were xeroxed, random black patches, lightly visible text,
etc., and also improving the quality of the image for better optical character
recognition system (OCR) performance. Removing noise from scanned documents is
a very important step before the documents as this noise can severely affect
the performance of an OCR system. The experiments in this paper have shown
promising results as the model is able to learn a variety of ordinary as well
as unusual noises and rectify them efficiently.Comment: 10 pages, 5 figures, attempting for publication in International
Journal on Document Analysis and Recognition (IJDAR
Neutron Diffraction Studies on La2-xDyxCa2xBa2Cu4+2xOz Superconductors
Structural studies on Dy-substituted La-2125 type superconductors have been
carried out by neutron diffraction experiments at room temperature using a
monochromatic neutron beam of wavelength lambda = 1.249 Angstroms. A series of
samples with La2-xDyxCa2xBa2Cu4+2xOz stoichiometric composition, for x = 0.1 -
0.5, have been studied for their structural properties. A tetragonal Y-123 unit
cell was taken as the starting model for the Rietveld analysis. All the samples
fit into the starting model, exhibiting no structural transition taking place
with increasing dopant concentration. The results of Rietveld analysis and
structural properties are discussed in detail
Critical current density and flux pinning in La2-xPrxCa2xBa2Cu4+2xOz (x = 0.1 - 0.5) superconductors
Polycrystalline La2-xPrxCa2xBa2Cu4+2xOz (LPCaBCO) compounds with x = 0.1 -
0.5 were synthesized by solid-state reaction method and studied by room
temperature X-ray diffraction, dc resistivity, dc magnetization and iodometry.
The superconducting transition temperatures in these tetragonal triple
perovskite compounds increases from 32 to 62 K (Tconset values) with increasing
dopant concentration. The mixing of rare earth La3+ and Pr3+/4+ ions at rare
earth site (La3+) along with substitution of divalent Ca2+ results in the
shrinkage of unit cell volume. The contraction of unit cell volume due to
larger ion being substituted by smaller ions, gives rise to creation of pinning
centers in the unit cell leading to increase in critical current density and
flux pinningComment: To be published in Solid State Communications (2004
Swift-heavy-ion-irradiation-induced enhancement in electrical conductivity of chemical solution deposited La0.7Ba0.3MnO3 thin films
Epitaxial thin films of La0.7Ba0.3MnO3 manganite, deposited using Chemical
Solution Deposition technique, were irradiated by 200 MeV Ag+15 ions with a
maximum ion dose up to 1x10^12 ions/cm2. Temperature- and magnetic
field-dependent resistivity measurements on all the films (before and after
irradiation) reveal a sustained decrease in resistivity with increasing ion
dose. A maximum dose of 1x10^12 ions/cm2 suppresses resistivity by factors of 3
and 10, at 330 K [insulator-metal (I-M) transition] and at 10 K, respectively.
On the other hand, with increasing ion dose, the magnetoresistance (MR)
enhances in the vicinity of I-M transition but decreases at low temperatures.
These results, corroborated by surface morphology of films, suggest that the
origin of such properties lies in the irradiation induced improved
crystallinity and epitaxial orientation, enhanced connectivity between grains,
and conglomeration of grains which result in better conductivity at grain
boundaries.Comment: To appear in 'Applied Physics Letters
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