a concept related to the spectrum of a graph is that of energy. the energy e(g) of a graph g is equal to the sum of the absolute values of the eigenvalues of the adjacency matrix of g . the laplacian energy of a graph g is equal to the sum of distances of the laplacian eigenvalues of g and the average degree d(g) of g. in this paper we introduce the concept of laplacian energy of fuzzy graphs. ...

Evolution of the main signal in a Lorentz dispersive medium is considered. The signal propagating in the medium is excited by a sine-modulated pulse signal, with its envelope described by a hyperbolic tangent function. Both uniform and non-uniform asymptotic representations for the signal are found. It is shown when the uniform representation can be reduced to the non-uniform one. The results o...

We discuss the behaviour of vertices and inflexions of one-parameter families of plane curves which include a singular member. These arise a sections of smooth surfaces by families of planes parallel to the tangent plane at a given point. We cover all the generic cases, namely elliptic (A1), umbilic (A1), hyperbolic (A1), parabolic (A2) and cusp of Gauss (A3) points. This work is preliminary to...

In this paper, we study global stabilization and synchronization of n-scroll chaotic attractors for a modified Chua’s circuit with hyperbolic tangent function using feedback control strategy. In particular, for any given equilibrium point of the modified Chua’s circuit, we design simple and explicit controllers to globally exponentially stabilize the system. Simple controllers are also designed...

Abstract: From the approximate symmetry point of view, the perturbed burgers equation is investigated. The symmetry of a system of the corresponding PDEs which approximates the perturbed burgers equation is constructed and the corresponding general approximates symmetry reduction is derived, which enables infinite series solutions and general formulae. Study shows that the similarity solutions ...

We have investigated the transmission and reflection properties of structures incorporating left-handed materials with graded index of refraction. We present an exact analytical solution to Helmholtz' equation for a graded index profile changing according to a hyperbolic tangent function along the propagation direction. We derive expressions for the field intensity along the graded index struct...

We discuss the behaviour of vertices and inflexions of one-parameter families of plane curves which include a singular member. These arise a sectons of smooth surfaces by families of planes parallel to the tangent plane at a given point. We cover all the generic cases, namely elliptic, umbilic, hyperbolic, parabolic and cusp of Gauss points. This work is preliminary to an investigation of symme...

Chow, Li and Yi in [2] proved that the majority of the unperturbed tori on submanifolds will persist for standard Hamiltonian systems. Motivated by their work, in this paper, we study the persistence and tangent frequencies preservation of lower dimensional invariant tori on smooth sub-manifolds for real analytic, nearly integrable Hamiltonian systems. The surviving tori might be elliptic, hype...

A constant angle surface in Minkowski space is a spacelike surface whose unit normal vector field makes a constant hyperbolic angle with a fixed timelike vector. In this work we study and classify these surfaces. In particular, we show that they are flat. Next we prove that a tangent developable surface (resp. cylinder, cone) is a constant angle surface if and only if the generating curve is a ...

Biophysical models predicting the relaxation of cardiomyocytes1 take into account a lot more variables than regression models analysing the left ventricular relaxation in human and animal hearts. These isochoric (isovolumic) pressure decay curves are often described by an exponential2 or logistic3 time constant. Both these three–parametric regression models are regarded unsatisfactory4, 5. Cons...