Volume 5 (2009) Issue 1

Abstract: The velocity field and associated shear stress corresponding to the longitudinal oscillatory flow of a second grade fluid, between two infinite coaxial circular cylinders, are determined by means of Laplace and Hankel transforms. The flow is due to both of the cylinders that at \(t = 0^+\) suddenly begin to oscillate along their common axis with different angular frequencies of their respective velocities. The solutions for the motion between the cylinders, when one of them is at rest, can be obtained from our general solutions. Furthermore, the corresponding solutions for the similar flow of Newtonian fluid are also obtained as limiting case. The flows of second grade and Newtonian fluids are compared graphically by plotting their velocity profiles.

Abstract: In this paper we introduce the notions of right F-derivation and left F-derivation of a BCI-algebra and some related properties are explored.

Abstract: Here first we will prove the existence of fixed points for a weakly continuous, strictly quasi bounded operator on a reflexive Banach space and a completely continuous, strictly quasi bounded operator on any normed linear space. Using these results we can deduce the existence of eigen values and surjectivity of quasi bounded operator in similar situations.

Abstract: For two vertices u and v in a graph \(G = (V, E)\), the detour distance \(D(u, v)\) is the length of a longest \(u–v\) path in \(G\). A \(u–v\) path of length \(D(u, v)\) is called a \(u–v\) detour. A set \(S ⊆ V\) is called a detour set of \(G\) if every vertex in \(G\) lies on a detour joining a pair of vertices of \(S\). The detour number \(dn(G)\) of G is the minimum order of its detour sets and any detour set of order \(dn(G)\) is a detour basis of \(G\). A set \(S ⊆ V\) is called a connected detour set of \(G\) if S is detour set of \(G\) and the subgraph \(G[S]\) induced by S is connected. The connected detour number \(cdn(G)\) of \(G\) is the minimum order of its connected detour sets and any connected detour set of order \(cdn(G)\) is called a connected detour basis of \(G\). Graphs G with detour diameter \(D ≤ 4\) are characterized when \(cdn(G) = p\), \(cdn(G) = p−1\), \(cdn(G) = p−2\) or \(cdn(G) = 2\). A subset \(T\) of a connected detour basis \(S\) of \(G\) is a forcing subset for \(S\) if \(S\) is the unique connected detour basis containing \(T\). The forcing connected detour number \(fcdn(S)\) of \(S\) is the minimum cardinality of a forcing subset for \(S\). The forcing connected detour number \(fcdn(G)\) of \(G\) is \(min{fcdn(S)}\), where the minimum is taken over all connected detour bases \(S\) in \(G\). The forcing connected detour numbers of certain classes of graphs are determined. It is also shown that for each pair \(a\), \(b\) of integers with \(0 ≤ a < b\) and \(b ≥ 3\), there is a connected graph \(G\) with \(fcdn(G) = a\) and \(cdn(G) = b\).

Abstract: The velocity field and the shear stress corresponding to the unsteady flow of a generalized Oldroyd-B fluid in an infinite circular cylinder subject to a longitudinal time-dependent shear stress are determined by means of Hankel and Laplace transforms. The exact solutions, written in terms of the generalized \(G\)-functions, satisfy all imposed initial and boundary conditions. The similar solutions for ordinary Oldroyd-B, ordinary and generalized Maxwell, ordinary and generalized second grade as well as for Newtonian fluids are obtained as limiting cases of our general solutions.

Abstract: For given graphs \(G\) and \(H\), the Ramsey number \(R(G, H)\) is the least natural number n such that for every graph \(F\) of order \(n\) the following condition holds: either \(F\) contains \(G\) or the complement of \(F\) contains \(H\). Beaded wheel \(BW_{2,m}\) is a graph of order \(2m + 1\) which is obtained by inserting a new vertex in each spoke of the wheel \(W_m\). In this paper, we determine the Ramsey number of paths versus Beaded wheels: \(R(P_n, BW_{2,m}) = 2n − 1\) or \(2n\) if \(m ≥ 3\) is even or odd, respectively, provided \(n ≥ 2m^2 − 5m + 4\).

Abstract: This paper presents a computational technique for Fredholm and Volterra integral equations of the second kind. The method based upon hybrid functions approximation. The properties of hybrid functions consisting of block-pulse functions and legendre polynomials are presented. The operational matrices of integration and product are utilized to reduce the computation of integral equation into some algebraic equations. Illustrative examples are included to demonstrate the validity and applicability of the technique.

Abstract: A two-parameter family of piecewise \(C^2\) rational quintic functions is presented along with an error investigation for the approximation of an arbitrary \(C^3\) function. The two parameters have a direct geometric interpretation making their use straightforward. Illustrations of their effect on the shape of the rational function are given. The relaxed continuity constraints and the increased flexibility via the two parameters make the
proposed function a suitable candidate for interactive CAD.

Abstract: For a connected graph \(G\) of order \(p ≥ 2\), a set \(S ⊆ V (G)\) is an \(x\)-geodominating set of \(G\) if each vertex \(v ∈ V (G)\) lies on an \(x-y\) geodesic for some element y in \(S\). The minimum cardinality of an \(x\)-geodominating set of G is defined as the \(x\)-geodomination number of \(G\), denoted by gx(G). An \(x\)-geodominating set of cardinality \(g_x(G)\) is called a \(g_x\)-set of \(G\). A connected \(x\)-geodominating set of G is an \(x\)-geodominating set S such that the subgraph \(G[S]\) induced by \(S\) is connected. The minimum cardinality of a connected \(x\)-geodominating set of \(G\) is defined as the connected \(x\)-geodomination number of \(G\) and is denoted by \(cg_x(G)\). A connected \(x\)-geodominating set of cardinality \(cg_x(G)\) is called a \(cg_x\)-set of \(G\). We determine bounds for it and find the same for some special classes of graphs. If \(p, a\) and \(b\) are positive integers such that \(2 ≤ a ≤ b ≤ p − 1\), then there exists a connected graph G of order \(p\), \(g_x(G) = a\) and \(cg_x(G) = b\) for some vertex \(x\) in \(G\). Also, if \(p\), \(d\) and \(n\) are integers such that \(2 ≤ d ≤ p − 2\) and \(1 ≤ n ≤ p\), then there exists a connected graph \(G\) of order \(p\), diameter \(d\) and \(cg_x(G) = n\) for some vertex \(x\) in \(G\). For positive integers \(r\), \(d\) and \(n\) with \(r ≤ d ≤ 2r\), there exists a connected graph \(G\) with rad \(G = r\), \(diam G = d\) and \(cg_x(G) = n\) for some vertex \(x\) in \(G\).