Abstract: In this paper, a two-channel secure communication
using fractional chaotic systems is presented. Conditions for chaos
synchronization have been investigated theoretically by using Laplace
transform. To illustrate the effectiveness of the proposed scheme, a
numerical example is presented. The keys, key space, key selection
rules and sensitivity to keys are discussed in detail. Results show that
the original plaintexts have been well masked in the ciphertexts yet
recovered faithfully and efficiently by the present schemes.
Abstract: This paper presents a linear stability analysis of
natural convection in a horizontal layer of a viscoelastic
nanofluid. The Oldroyd B model was utilized to describe the
rheological behavior of a viscoelastic nanofluid. The model
used for the nanofluid incorporated the effects of Brownian
motion and thermophoresis. The onset criterion for stationary
and oscillatory convection was derived analytically. The effects
of the Deborah number, retardation parameters, concentration
Rayleigh number, Prandtl number, and Lewis number on the
stability of the system were investigated. Results indicated that
there was competition among the processes of thermophoresis,
Brownian diffusion, and viscoelasticity which caused
oscillatory rather than stationary convection to occur.
Oscillatory instability is possible with both bottom- and
top-heavy nanoparticle distributions. Regimes of stationary and
oscillatory convection for various parameters were derived and
are discussed in detail.
Abstract: We propose a new perspective on speech
communication using blind source separation. The original speech is
mixed with key signals which consist of the mixing matrix, chaotic
signals and a random noise. However, parts of the keys (the mixing
matrix and the random noise) are not necessary in decryption. In
practice implement, one can encrypt the speech by changing the noise
signal every time. Hence, the present scheme obtains the advantages
of a One Time Pad encryption while avoiding its drawbacks in key
exchange. It is demonstrated that the proposed scheme is immune
against traditional attacks.