فهرست مطالب

  • Volume:5 Issue:1, 2014
  • تاریخ انتشار: 1393/02/25
  • تعداد عناوین: 7
|
  • F. Fayazi, S. Rahimi Sharbaf Pages 1-10
    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. Let G be a fuzzy graph with n vertices and m edges. The Laplacian spectrum of fuzzy graph G is defined. The Laplacian energy of G has been recently defined. Section 2 consists of preliminaries and definition of Laplacian energy of a fuzzy graph and in Section 3, we present some results on Laplacian energy of a fuzzy graph.Some bounds o Laplacian energy of fuzzy graphs are also given.
    Keywords: Fuzzy graph, Fuzzy laplacian matrix, Laplacian spectrum, Laplacian energy (of fuzzy graph)
  • M. Ghorbani, M. Songhori Pages 11-18
    The chromatic number of a graph G, denoted by χ(G), is the minimum number of colors such that G can be colored with these colors in such a way that no two adjacent vertices have the same color. A clique in a graph is a set of mutually adjacent vertices. The maximum size of a clique in a graph G is called the clique number of G. The Turán graph Tn(k) is a complete k-partite graph whose partition sets differ in size by at most 1. The Wiener number [1] is the first reported distance based topological index and is defined as half sum of the distances between all the pairs of vertices in a molecular graph. Recently, some new versions of Zagreb indices are considered by mathematicians. In the present study we compute some bounds of multiplicative Zagreb indices and then we study these topological indices by using concept of chromatic number and clique number.
    Keywords: multiplicative Zagreb index, clique number, independence number, chromatic number
  • Ž. K. VukiĆeviĆ G. Popivoda Pages 19-29
    We give sharp upper bounds on the Zagreb indices and lower bounds on the Zagreb coindices of chemical trees and characterize the case of equality for each of these topological invariants.
    Keywords: Zagreb index, Zagreb coindex, chemical tree
  • A. Huber Pages 31-46
    In the present study an alternative model allows the extension of the Debye-Hückel Theory (DHT) considering time dependence explicitly. From the Electro-Quasistatic approach (EQS) done in earlier studies time dependent potentials are suitable to describe several phenomena especially conducting media as well as the behaviour of charged particles in arbitrary solutions acting as electrolytes.This leads to a new formulation of the meaning of the nonlinear Poisson-Boltzmann Equation (PBE). If a concentration and/or flux gradient of particles is considered the original structure of the mPBE will be modified leading to a new nonlinear partial differential equation (nPDE) of the third order. It is shown how one can derive classes of solutions for the potential function analytically by application of an algebraic method. The benefit of the mathematical tools used here is the fact that closed-form solutions can be calculated without any numerical approximations.
    Keywords: Nonlinear partial differential equations, Debye, Hückel Theory, Poisson, Boltzmann Equation
  • A. Saadatmandi, N. Nafar, S. P. Toufighi Pages 47-61
    In chemical engineering, several processes are represented by singular boundary value problems. In general, classical numerical methods fail to produce good approximations for the singular boundary value problems. In this paper, Chebyshev finite difference (ChFD) method and DTM-Pad´e method, which is a combination of differential transform method (DTM) and Pad´e approximant, are applied for solving singular boundary value problems arising in the reaction cum diffusion process in a spherical biocatalyst. ChFD method can be regarded as a non-uniform finite difference scheme and DTM is a numerical method based on the Taylor series expansion, which constructs an analytical solution in the form of a polynomial. The main advantage of DTM is that it can be applied directly to nonlinear ordinary without requiring linearization, discretization or perturbation. Therefore, it is not affected by errors associated to discretization. The results obtained, are in good agreement with those obtained numerically or by optimal homotopy analysis method.
    Keywords: Diffusion, Reaction, Biocatalyst, Effectiveness factor, Differential transform method, Chebyshev finite difference method
  • F. Koorepazan-Moftakhar, Kh. Fathalikhani Pages 63-68
    In this paper, we calculate the eccentric connectivity index and the eccentricity sequence of two infinite classes of fullerenes with 50 + 10k and 60 + 12k (k in N) carbon atoms.
    Keywords: Eccentricity sequence, eccentric connectivity index, Fullerene
  • A. Sanami Pages 69-75
    Let h be a finite dimensional complex Hilbert space, b(h)+ be the set of all positive semi-definite operators on h and Phi is a (not necessarily linear) unital map of B(H) + preserving the Entropy-Gibbs transformation. Then there exists either a unitary or an anti-unitary operator U on H such that Phi(A) = UAU* for any B(H) +. Thermodynamics, a branch of physics that is concerned with the study of heat (thermo) and power (dynamics), might at first seem more important for engineers trying to in- vent a new engine than for biochemists trying to understand the mechanisms of life. However, since chemical reactions involve atoms and molecules that are bound by the laws of physics, studying thermodynamics should be a priority for every aspiring biochemist. There are two laws of thermodynamics that are important to the study of biochemistry. These two laws have to do with energy and order both essential for life as we know it. It is easy to understand that our bodies need energy to function from the visible muscle movement that gets us where we want to go, to the microscopic cellular processes that keep our brains thinking and our organs functioning. Order is also important. Our bodies represent a high degree of order: atoms and molecules are meticulously organized into a complex system ranging in scale from the microscopic to the macroscopic.
    Keywords: Preserver transformations, entropy, rank one operator, Gibbs free energy