Authors:A. S. Hassan Abstract: Abstract In this article, the effects of time delay and carrying capacity in the dynamics of viral phytoplankton and consistence numerics are studied. Basic properties and stabilities of equilibria are rigorously analyzed and conditions for stability switches are found. A dynamically consistent nonstandard finite difference scheme for the continuous delay model is designed to verify the results and reveal some interesting features of the model. Some ecological implications and interpretations are provided. PubDate: 2018-01-04 DOI: 10.1007/s13370-017-0541-5

Authors:Mehdi Bastani; Davod Khojasteh Salkuyeh Pages: 999 - 1010 Abstract: Abstract In this paper, the non-Hermitian positive definite linear systems are solved via preconditioned Krylov subspace methods such as the generalized minimal residual (GMRES) method. To do so, the two-parameter generalized Hermitian and skew-Hermitian splitting (TGHSS) iteration method is applied to establish an m-step polynomial preconditioner. Some theoretical results are also given to investigate the convergence properties of the preconditioned method. Three numerical examples are presented to demonstrate the performance of the new method and to compare it with a recently proposed method. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0489-5 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Saleem Abdullah; Shah Hussain Pages: 1033 - 1059 Abstract: Abstract In this article, a new generalization of intuitionsitic fuzzy bi-ideals of a semigroup considered so called \((\alpha ,\beta )\) -intuitionistic fuzzy bi-ideals, (1, 2)-ideals in a semigroup. We combine the notion of intuitionsitic fuzzy point and intuitionistic fuzzy sets to defined different types of intuitionsitic fuzzy bi-ideals of a semigroups. We investigate different properties of these notions and their relationships, particularly, we define \((\in ,\in \vee q)\) -intuitionistic fuzzy bi-ideals and (1, 2) ideals in semigroups. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0501-0 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Kanak Kanti Baishya Pages: 1061 - 1066 Abstract: Abstract Recently the present author introduced the notion of generalized quasi-conformal curvature tensor which bridges conformal curvature tensor, concircular curvature tensor, projective curvature tensor and conharmonic curvature tensor. The object of the present paper is to find out curvature conditions for which Ricci solitons in Sasakian manifolds are sometimes shrinking and some other time remain expanding. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0502-z Issue No:Vol. 28, No. 7-8 (2017)

Authors:P. Mafuta Pages: 1067 - 1074 Abstract: Abstract Let G be a simple 2-connected, \(C_4\) -free graph with minimum degree \(\delta (G)\ge 4\) and leaf number L(G) such that \(\delta (G)\ge \displaystyle \frac{1}{2}L(G)\) . We show that G is Hamiltonian. In addition, we provide family of graphs to show that the results are best possible for aforementioned class of graphs. The results, apart from supporting the conjecture (Graffiti.pc 190) of the computer program Graffiti.pc, instructed by DeLaVi \({\tilde{n}}\) a, provide a new sufficient condition for Hamiltonicity in \(C_4\) -free graphs. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0503-y Issue No:Vol. 28, No. 7-8 (2017)

Authors:F. Baghery; N. Khelfallah; B. Mezerdi; I. Turpin Pages: 1075 - 1092 Abstract: Abstract We consider a control problem where the system is driven by a decoupled as well as a coupled forward–backward stochastic differential equation. We prove the existence of an optimal control in the class of relaxed controls, which are measure-valued processes, generalizing the usual strict controls. The proof is based on some tightness properties and weak convergence on the space \(\mathcal {D}\) of càdlàg functions, endowed with the Jakubowsky S-topology. Moreover, under some convexity assumptions, we show that the relaxed optimal control is realized by a strict control. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0504-x Issue No:Vol. 28, No. 7-8 (2017)

Authors:Yuji Liu Pages: 1093 - 1113 Abstract: Abstract In this article, existence results of solutions of a class of boundary value problems of nonlinear singular multi-term fractional differential models with impulses on half line involving higher order Riemann–Liouville fractional derivatives are established. Our analysis rely on a well known fixed point theorems. Examples are presented to illustrate the main theorems. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0505-9 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Nipen Saikia; Chayanika Boruah Pages: 1131 - 1141 Abstract: Abstract We use Ramanujan’s mixed modular equations to evaluate some new values of the parameter \(J_n\) involving Ramanujan’s theta-function \(f(-q)\) . The values \(J_n\) are then used to evaluate new explicit values of the Ramanujan–Selberg continued fraction. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0507-7 Issue No:Vol. 28, No. 7-8 (2017)

Authors:B. Vasudevan; R. Udhayakumar; C. Selvaraj Pages: 1143 - 1156 Abstract: Abstract In this paper, we study some properties and behavior of finite Gorenstein FI-flat dimension through the methods of relative homological algebra. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0508-6 Issue No:Vol. 28, No. 7-8 (2017)

Authors:S. El Ouadih; R. Daher Pages: 1157 - 1165 Abstract: Abstract In this paper, using a generalized translation operator, we obtain an analog of Younis’s Theorem 5.2 in Younis (Int J Math Math Sci 9:301–312, 1986) for the generalized Fourier-Bessel transform for functions satisfying the Fourier-Bessel Dini Lipschitz condition in the space \(L_{\alpha ,n}^{2}\) . PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0509-5 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Miloud Mihoubi; Mourad Rahmani Pages: 1167 - 1183 Abstract: Abstract In this paper, we show that the r-Stirling numbers of both kinds, the r-Whitney numbers of both kinds, the r-Lah numbers and the r-Whitney-Lah numbers form particular cases of a family of polynomials forming a generalization of the partial Bell polynomials. We deduce the generating functions of several restrictions of these numbers. In addition, a new combinatorial interpretations is presented for the r-Whitney numbers and the r-Whitney-Lah numbers. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0510-z Issue No:Vol. 28, No. 7-8 (2017)

Authors:D. Bayrak; S. Yamak Pages: 1185 - 1192 Abstract: Abstract Many studies have investigated lattices of fuzzy algebraic systems. One of them belongs to Borzooei et al. (Soft Comput 12:739–749, 2008) who found some properties of lattices of fuzzy algebraic structures. In this study, we solve the problem of finding necessary and sufficient conditions for distributivity and modularity of lattice of fuzzy hyperideals of a hyperring which was one of the open problems in Borzooei’s paper. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0511-y Issue No:Vol. 28, No. 7-8 (2017)

Authors:Aissa Guesmia Pages: 1253 - 1284 Abstract: Abstract In this paper, we consider a vibrating system of Timoshenko-type in a bounded one-dimensional domain with discrete time delay and complementary frictional damping and infinite memory controls all acting on the transversal displacement. We show that the system is well-posed in the sens of semigroup and that, under appropriate assumptions on the weights of the delay and the history data, the stability of the system holds in case of the equal-speed propagation as well as in the opposite case in spite of the presence of a discrete time delay, where the decay rate of solutions is given in terms of the smoothness of the initial data and the growth of the relaxation kernel at infinity. The results of this paper extend the ones obtained by the present author and Messaoudi in (Acta Math Sci 36:1–33, 2016) to the case of presence of discrete delay. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0514-8 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Peter V. Danchev Pages: 1285 - 1295 Abstract: Abstract We define and completely describe the structure of weakly invo-clean rings possessing identity. We show that these rings are clean but neither weakly nil-clean nor invo-clean, and thus they have some new exotic properties different to those established by Breaz et al. (J Algebra Appl 15, 2016) and Danchev (Commun Korean Math Soc 32:19–27, 2017), respectively. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0515-7 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Ibrahima Bakayoko; Bakary Manga Pages: 1297 - 1311 Abstract: Abstract In this paper we introduce modules over both left and right Hom-alternative algebras. We give some constructions of left and right Hom-alternative modules and give various properties of both, as well as examples. Then, we prove that morphisms of left alternative algebras extend to morphisms of left Hom-alternative algebras. Next, we introduce comodules over Hom–Poisson coalgebras and show that we may obtain a structure map of a comodule over a Hom–Poisson coalgebra from a given one. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0516-6 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Pierre Kouadjo Brou; Youssouf M. Diagana Pages: 1313 - 1325 Abstract: Abstract Let R be a ring and A a subring of R. Let \(h=\left( \mathcal {M} _{n}\right) _{n\in \mathbb {Z}\cup \left\{ +\infty \right\} }\) be a family of subgroups of an R-module \(\mathcal {M}\) . We say that h is an A-quasi-graduation of \(\mathcal {M}\) if for every \(p\in \mathbb {N}, \mathcal {M}_{p}\) is a sub-A-module of R with \(\mathcal {M}_{\infty }=(0)\) . We present weak notions of J-independence for different extensions of the analytic spread. We show that under some conditions they coincide with \(\lim \nolimits _{n \rightarrow +\infty }\ell _{J}(h^{(n!)},A,k)\) , where, for all integers \(p, h^{(p)} = (\mathcal {M}_{pn})_{n\in \mathbb {Z}\cup \left\{ +\infty \right\} }\) and where \(\ell _J (h^{(p)}, A, k)\) is the maximum number of elements of J which are J-independent of order k with respect to the A-quasi-graduation \(h^{(p)}\) of the R-module \(\mathcal {M}\) . PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0517-5 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Ehmet Kasim; Geni Gupur Pages: 1327 - 1348 Abstract: Abstract In this paper we consider an M/G/1 queueing model with single working vacation and vacation interruption. By studying the spectral properties of the corresponding operator we obtain that the time-dependent solution of the model strongly converges to its steady-state solution. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0518-4 Issue No:Vol. 28, No. 7-8 (2017)

Authors:Ayşe Zeynep Azak; Melek Masal Pages: 1349 - 1355 Abstract: Abstract We have given a generalization of one parameter special Frenet motion to type-2 Bishop motion in Euclidean 3-space \(E^3\) . Type-2 Bishop motion have been defined for space curve \(\beta \) and then type-2 Bishop Darboux vector of this motion has been calculated for fixed and moving spaces in \(E^3\) . Also, we have showed that type-2 Bishop rotation for space curves is decomposed into two simultaneous rotations. One of the axes of this simultaneous rotations is a parallel of the binormal vector of the curve, the other is the direction of the type-2 Bishop Darboux vector of the curve. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0519-3 Issue No:Vol. 28, No. 7-8 (2017)

Authors:G. Murugusundaramoorthy Pages: 1357 - 1366 Abstract: Abstract The purpose of the present paper is to establish connections between various subclasses of analytic univalent functions by applying certain convolution operator involving Poisson distribution series. To be more precise,we investigate such connections with the classes of analytic univalent functions of \(\beta \) -starlike and \(\beta \) -uniformly convex functions of order \(\alpha \) in the open unit disk \({\mathbb {U}}\) . Further we point out some consequences of our main results. PubDate: 2017-12-01 DOI: 10.1007/s13370-017-0520-x Issue No:Vol. 28, No. 7-8 (2017)

Authors:Rasoul Soleimani Abstract: Abstract In this paper, we introduce the notion of a central B-automorphism of a finite B-algebra. Also some properties of a finite B-algebra and B-automorphism algebra are investigated. PubDate: 2017-12-19 DOI: 10.1007/s13370-017-0540-6