1,141 research outputs found
An efficient data masking for securing medical data using DNA encoding and chaotic system
Data security is utmost important for ubiquitous computing of medical/diagnostic data or images. Along with must consider preserving privacy of patients. Recently, deoxyribose nucleic acid (DNA) sequences and chaotic sequence are jointly used for building efficient data masking model. However, the state-of-art model are not robust against noise and cropping attack (CA). Since in existing model most digits of each pixel are not altered. This work present efficient data masking (EDM) method using chaos and DNA based encryption method for securing health care data. For overcoming research challenges effective bit scrambling method is required. Firstly, this work present an efficient bit scrambling using logistic sine map and pseudorandom sequence using chaotic system. Then, DNA substitution is performed among them to resist against differential attack (DA), statistical attack (SA) and CA. Experiment are conducted on standard considering diverse images. The outcome achieved shows proposed model efficient when compared to existing models
Comparison of History Effects in Magnetization in Weakly pinned Crystals of high- and low-T Superconductors
A comparison of the history effects in weakly pinned single crystals of a
high YBaCuO (for H c) and a low
CaRhSn, which show anomalous variations in critical current
density are presented via tracings of the minor magnetization
hysteresis loops using a vibrating sample magnetometer. The sample histories
focussed are, (i) the field cooled (FC), (ii) the zero field cooled (ZFC) and
(iii) an isothermal reversal of field from the normal state. An understanding
of the results in terms of the modulation in the plastic deformation of the
elastic vortex solid and supercooling across order-disorder transition is
sought.Comment: Presented in IWCC-200
Stable and Metastable vortex states and the first order transition across the peak effect region in weakly pinned 2H-NbSe_2
The peak effect in weakly pinned superconductors is accompanied by metastable
vortex states. Each metastable vortex configuration is characterized by a
different critical current density J_c, which mainly depends on the past
thermomagnetic history of the superconductor. A recent model [G. Ravikumar, et
al, Phys. Rev. B 61, R6479 (2000)] proposed to explain the history dependent
J_c postulates a stable state of vortex lattice with a critical current density
J_c^{st}, determined uniquely by the field and temperature. In this paper, we
present evidence for the existence of the stable state of the vortex lattice in
the peak effect region of 2H-NbSe_2. It is shown that this stable state can be
reached from any metastable vortex state by cycling the applied field by a
small amplitude. The minor magnetization loops obtained by repeated field
cycling allow us to determine the pinning and "equilibrium" properties of the
stable state of the vortex lattice at a given field and temperature
unambiguously. The data imply the occurence of a first order phase transition
from an ordered phase to a disordered vortex phase across the peak effect.Comment: 20 pages, 10 figures. Corresponding author: S. Ramakrishna
4-[(E)-(Hydroxyimino)methyl]-N,N-dimethylanilinium chloride
In the title compound, C9H13N2O+·Cl−, the cation, apart from the methyl groups, is almost planar, with a maximum deviation of 0.040 (1) Å; the methyl C atoms deviate by 0.389 (2) and −1.247 (1) Å, from the mean plane. In the crystal, cations and anions associate through C—H⋯Cl hydrogen bonds, forming a helical arrangement. In addition, intermolecular O—H⋯Cl, N—H⋯Cl and C—H⋯N interactions are observed
A study of supercooling of the disordered vortex phase via minor hysteresis loops in 2H-NbSe_2
We report on the observation of novel features in the minor hysteresis loops
in a clean crystal of NbSe_2 which displays a peak effect. The observed
behavior can be explained in terms of a supercooling of the disordered vortex
phase while cooling the superconductor in a field. Also, the extent of spatial
order in a flux line lattice formed in ascending fields is different from (and
larger than) that in the descending fields below the peak position of the peak
effect; this is attributed to unequal degree of annealing of the state induced
by a change of field in the two cases.Comment: 5 pages of text + 6 figures, submitted to Phys. Rev.
Critical depinning force and vortex lattice order in disordered superconductors
We simulate the ordering of vortices and its effects on the critical current
in superconductors with varied vortex-vortex interaction strength and varied
pinning strengths for a two-dimensional system. For strong pinning the vortex
lattice is always disordered and the critical depinning force only weakly
increases with decreasing vortex-vortex interactions. For weak pinning the
vortex lattice is defect free until the vortex-vortex interactions have been
reduced to a low value, when defects begin to appear with a simultaneous rapid
increase in the critical depinning force. In each case the depinning force
shows a maximum for non-interacting vortices. The relative height of the peak
increases and the peak width decreases for decreasing pinning strength in
excellent agreement with experimental trends associated with the peak effect.
We show that scaling relations exist between the distance between defects in
the vortex lattice and the critical depinning force.Comment: 5 pages, 6 figure
- …