1,755 research outputs found
Cryptographic Pseudo-Random Sequences from the Chaotic Henon Map
A scheme for pseudo-random binary sequence generation based on the
two-dimensional discrete-time Henon map is proposed. Properties of the proposed
sequences pertaining to linear complexity, linear complexity profile,
correlation and auto-correlation are investigated. All these properties of the
sequences suggest a strong resemblance to random sequences. Results of
statistical testing of the sequences are found encouraging. An attempt is made
to estimate the keyspace size if the proposed scheme is used for cryptographic
applications. The keyspace size is found to be large and is dependent on the
precision of the computing platform used.Comment: Submitted to the Indian Academy of Sciences for possible publication
in Sadhana (Academy Proceedings in Engineering Sciences). Results of
statistical tests included. Introduction revise
Dynamical Systems as Logic Gates
A scheme for logical computation using non-linear dynamical systems is
presented. Examples of discrete-time maps configured as AND, OR, NAND and NOR
gates are given. It is seen that the logical operations are flexible in the
sense that an AND gate can be transformed into an OR gate with a simple change
of a single parameter and vice-versa. Also, a NAND gate can be transformed into
a NOR gate and vice-versa. It is shown, by example, that the scheme can even be
extended to continuous-time flows. Since the NAND and NOR operations are
universal, it is possible to implement any switching function by
interconnecting blocks that realize these operations.Comment: 4 pages, 6 figures, 3 tables. Title-case corrected. Incorrect
references corrected. Submitted to Physical Review
Chaotic Sequences for Secure CDMA
One family each of repetitive and non-repetitive spreading sequences for
secure Direct Sequence Spread Spectrum communication are obtained from the
logistic map. The repetitive sequences are perfectly balanced and are found to
have sufficient linear complexity. Applicability of both the families to CDMA
communication is studied by examining their cross-correlation performance. The
cross-correlation is found to be comparable to and only rarely worse than that
of Gold sequences.Comment: 4 pages, PDF format, Presented at the 3rd National Conference on
Nonlinear Systems and Dynamics (NCNSD-2006), Ramanujan Institute for Advanced
Study in Mathematics, Chennai, 6-8 February 200
Effect of different Gaussian width on disappearance of flow
In the present paper, we reduce and enhance the scaled Gaussian width(SGW) by
30% from the normal SGW of the systems and see its effect on balance energy.
The scaled Gaussian width can be defined as the ratio of Gaussian width used
for any nuclei to the Gaussian width used for Au nuclei(i.e. 8.66 )
Isospin effects on fragment production
To understand the isospin effects in nearly symmetric nuclear matter we
performed a complete systematical theoretical study within an Isospin dependent
Quantum Molecular Dynamical Model (IQMD) and using Minimum Spanning Tree (MST)
algorithm. Simulations are carried out for the reactions
and . The collision
geometry is varied from central to peripheral. We find that neutron rich
colliding nuclei are better candidate to study the isospin effect
Rapidity distribution dependence of the transition energy in heavy-ion collisions
For the present analysis, simulations are carried out for thousand of events
for the reaction of 79Au197 + 79Au197 at semi-central geometry using a hard
equation of state. The whole of the analysis is performed for light charged
particles (LCP's). The transition from in-plane to out-of-plane is observed
only when the mid-rapidity region is included in the rapidity bin otherwise no
transition is observed. The transition energy is found to be strongly dependent
on the size of the rapidity bin. The transition energy is parameterized with a
straight line interpolation.Comment: 3 Pages, 2 Figure
Coherent Perfect Absorption: an electromagnetic perspective
We present a simple closed expression for determining the condition for
Coherent Perfect Absorption derived through electromagnetic wave treatment and
interface boundary conditions. Apart from providing physical insight this
expression can be used to estimate the values of various parameters required
for observation of coherent perfect absorption in a given medium characterized
by a complex dielectric constant. The results of the theoretical expression are
found to be in good agreement with those obtained through numerical
simulations
Experimental balance energies and isospin-dependent nucleon-nucleon cross-sections
The effect of different isospin-dependent cross-section on directed flow is
studied for variety of systems(for which experimental balance energies are
available) using an isospin-dependent Quantum Molecular Dynamic (IQMD) model.
We show that balance energies are sensitive towards isospin-dependent
cross-sections for light systems, while nearly no effect exist for heavier
nuclei. A reduced cross-section with stiff equation
of state is able to explain experimental balance energies in most of systems. A
power law behaviour is also given for the mass dependence of balance energy,
which also follow N/Z dependence.Comment: 15 pages, 9 figure
Effect of spatial constraints on fragment production
Multifragmentation is the most extensively studied phenomena in this energy
domain. In the past people have tried to develop various methods of
clusterization[1]. Among these methods minimum spanning tree[1] is one of the
fastest method. In the present study our aim is to understand the role of
spatial constraints on fragmentation
Effect of density dependent symmetry energy on Elliptical flow
The effect of the density dependent symmetry energy on elliptical flow is
studied using isospin-dependent quantum molecular dynamics model(IQMD). We have
used the reduced isospin-dependent cross-section with soft equation of state to
study the sensitivity of elliptical flow towards symmetry energy. Aim of the
present study is to pin down the Elliptical flow for the various forms of the
density dependent symmetry energy.Comment: submitted to DAE Symposium on Nuclear Physics, December 26-30, 2011,
Department of Nuclear Physics, Andhra University, Visakhapatnam, A.P., Indi
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