12 research outputs found

    Magnetohydrodynamic mixed convection flow of Jeffery fluid with thermophoresis, Soret and Dufour effects and convective condition

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    The aim of this paper is to investigate heat and mass transfer of Jeffery fluid on a stretching sheet. Moreover, the influence of magnetic field with mixed convection, convective boundary condition and Soret and Dufour effects is also brought into the consideration along with chemical reaction and thermophoresis condition. The problem is modeled by system of partial differential equations and solutions are obtained by optimal homotopy analysis method. In addition, for comprehensive interpretation of the influence of the system parameters results are shown by graphs and tables

    Action of the mobius group ¨ M = hx, y : x 2 = y 6 = 1i on certain real quadratic fields

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    Let C 0 = C ∪ {∞} be the extended complex plane and M = ­ x, y : x 2 = y 6 = 1® , where x(z) = −1 3z and y(z) = −1 3(z+1) are the linear fractional transformations from C 0 → C 0 . Let m be a squarefree positive integer. Then Q∗ ( √ n) = { a+ √ n c : a, c 6= 0, b = a 2−n c ∈ Z and (a, b, c) = 1} where n = k 2m, is a proper subset of Q( √ m) for all k ∈ N. For non-square n = 3h Qr i=1 p ki i , it was proved in an earlier paper by the same authors that the set Q 000 ( √ n) = { α t : α ∈ Q∗ ( √ n), t = 1, 3} is M-set ∀ h ≥ 0 whereas if h = 0 or 1, then Q∗∗∗√ n) = { a+ √ n c : a+ √ n c ∈ Q∗ ( √ n) and 3 | c} is an M-subset of Q 000 ( √ n) = Q∗ ( √ n) ∪ Q∗∗∗( √ 9n). In this paper we prove that if h ≥ 2, then Q 000 ( √ n) = (Q∗ ( pn 9 )\Q∗∗∗( pn 9 ))∪Q∗ ( √ n)∪Q∗∗∗( √ 9n) and also determine its proper M-subsets. In particular Q( √ m) \ Q = ∪Q 000 ( √ k 2m) for all k ∈ N

    On the heights of power digraphs modulo nn

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    summary:A power digraph, denoted by G(n,k)G(n,k), is a directed graph with Zn={0,1,,n1}\mathbb Z_{n}=\{0,1,\dots ,n-1\} as the set of vertices and E={(a,b) ⁣:akb(modn)}E=\{(a,b)\colon a^{k}\equiv b\pmod n\} as the edge set. In this paper we extend the work done by Lawrence Somer and Michal Křížek: On a connection of number theory with graph theory, Czech. Math. J. 54 (2004), 465–485, and Lawrence Somer and Michal Křížek: Structure of digraphs associated with quadratic congruences with composite moduli, Discrete Math. 306 (2006), 2174–2185. The heights of the vertices and the components of G(n,k)G(n,k) for n1n\geq 1 and k2k\geq 2 are determined. We also find an expression for the number of vertices at a specific height. Finally, we obtain necessary and sufficient conditions on nn such that each vertex of indegree 00 of a certain subdigraph of G(n,k)G(n,k) is at height q1q\geq 1

    Symmetry of iteration graphs

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    summary:We examine iteration graphs of the squaring function on the rings Z/nZ\mathbb{Z}/n\mathbb{Z} when n=2kpn = 2^{k}p, for pp a Fermat prime. We describe several invariants associated to these graphs and use them to prove that the graphs are not symmetric when k=3k=3 and when k5k\ge 5 and are symmetric when k=4k = 4

    On monogenity of certain pure number fields of degrees 2r3k7s2^r\cdot 3^k\cdot 7^s

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    summary:Let K=Q(α)K = \mathbb {Q} (\alpha ) be a pure number field generated by a complex root α\alpha of a monic irreducible polynomial F(x)=x2r3k7smZ[x] F(x) = x^{2^r\cdot 3^k\cdot 7^s} -m \in \mathbb{Z}[x], where rr, kk, ss are three positive natural integers. The purpose of this paper is to study the monogenity of KK. Our results are illustrated by some examples

    On power integral bases for certain pure number fields defined by x18mx^{18}-m

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    summary:Let K=Q(α)K={\mathbb Q}(\alpha) be a number field generated by a complex root α\alpha of a monic irreducible polynomial f(x)=x18mf(x)=x^{18}-m, m1m\neq \mp 1, is a square free rational integer. We prove that if m2 m \equiv 2 or 3(mod4)3 {\rm(mod }{ 4}) and m≢1(mod9)m\not\equiv \mp 1 {\rm(mod }{ 9}), then the number field KK is monogenic. If m1(mod4) m \equiv 1 {\rm(mod }{ 4}) or m1(mod9)m\equiv 1 {\rm(mod }{ 9}), then the number field KK is not monogenic
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