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 $fm^2$)

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 $_{124}Sn^{50}+_{124}Sn^{50}$ and $_{107}Sn^{50}+_{124}Sn^{50}$. 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 $\sigma = 0.9\sigma_{NN}$ 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 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

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