Cilt:68 Sayı:01 (2019)
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Item On b-coloring of central graph of some graphs(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Kalpana, M.; Vijayalakshmi, D.; Other; OtherThe b-chromatic number of G, denoted by ϕ(G), is the maximum k for which G has a b-coloring by k colors. A b-coloring of G by k colors is a proper k-coloring of the vertices of G such that in each color class i there exists a vertex x_{i} having neighbors in all the other k-1 color classes. Such a vertex x_{i} is called a b-dominating vertex, and the set of vertices {x₁,x₂…x_{k}} is called a b-dominating system. In this paper, we are going to investigate on the b-chromatic number of Central graph of Triangular Snake graph, Sunlet graph, Helm Graph, Double Triangular Snake graph, Gear graph, and Closed Helm graph are denoted as C(T_{n}), C(S_{n}), C(H_{n}), C(DT_{n}), C(G_{n}), C(CH_{n}) respectively.Item Approximate controllability of neutral integrodifferential inclusions via resolvent operators(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Tamilselvan, M.; Other; OtherIn this work, a set of sufficient conditions are established for the approximate controllability for neutral integrodifferential inclusions in Banach spaces. The theory of fractional power and α-norm is used because of the spatial derivatives in the nonlinear term of the system. Bohnenblust-Karlin's fixed point theorem is used to prove our main results. Further, this result is extended to study the approximate controllability for nonlinear functional control system with nonlocal conditions. An example is also given to illustrate our main results.Item Quasi-subordination and coefficient bounds for certain classes of meromorphic functions of complex order(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Zayed, H. M.; Bulut, Serap; Mostafa, A. O.; Other; OtherIn this paper, we obtain Fekete-Szegö functional |a₁-μa₀²| for functions of the classes Σ_{q}^{∗}(ϕ) and Σ_{q,λ,b}^{∗}(g,ϕ) using quasi-subordination. Sharp bounds for the Fekete-Szegö functional |a₁-μa₀²| are obtained. Also, applications of the main results for subclasses of functions defined by Bessel function are also considered.Item Structural derivatives on time scales(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Bayour, Benaoumeur; Torres, Delfim F. M.; Other; OtherWe introduce the notion of structural derivative on time scales. The new operator of differentiation unifies the concepts of fractal and fractional order derivative and is motivated by lack of classical differentiability of some self-similar functions. Some properties of the new operator are proved and illustrated with examples.Item Smarandache Curves in three dimensional Lie groups(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Değirmen, Caner; Okuyucu, O. Zeki; Yıldız, Ö. Gökmen; Other; OtherIn this paper, we introduce special Smarandache curves and obtain Frenet apparatus of a Smarandache curve in three dimensional Lie groups with a bi-invariant metric. Moreover, we give some relations between a helix or a slant helix curve and its Smarandache curve in three dimensional Lie groups.Item Actions of soft groups(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Oğuz, Gülay; İcen, İlhan; Gürsoy, M. Habil; Zihin Engelliler Öğretmenliği; OtherThe soft set theory proposed by Molodtsov is a recent mathematical approach for modeling uncertainty and vagueness. The main aim of this study is to introduce the concept of soft action by combining soft set theory with the action which is an important concept in dynamical systems theory. Moreover, different types of soft action are presented and some important characterizations are given. Finally, we define the concept of soft symmetric group and present the relation between the soft action and soft symmetric group, as a similar result to the classical Cayley's Theorem.Item A new perspective of transmuted distribution(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Hameldarbandı, Monireh; Yılmaz, Mehmet; İktisat; Fen FakültesiRegarding the concept of quadratic rank transmutation, a new distribution with convex combinations of the life distributions of two-component systems (series and parallel systems) whose component lifetimes are not identical is obtained. This proposed distribution has extra parameters compared to the known transmuted distribution. It can also be represented by two different baseline distributions. So, it is very flexible in modeling. A description of the various structural properties of the subject distribution along with its reliability behavior is provided. Finally, a real data analysis is performed for this distribution and it is found that this class is more flexible.Item Reviving some geometric aspects of shrinkage estimation in linear models(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Akdeniz, Fikri; Öztürk, Fikri; İstatistik; Fen FakültesiIt is well known that the least squares estimator is the best linear unbiased estimator of the parameter vector in a classical linear model. But, it is `too long' as a vector and unreliable, confidence intervals are broad for some components especially in the case of multicollinearity. Shrinkage (contraction) type estimators are efficient remedial tools in order to solve problems caused by multicollinearity. In this study, we consider a class of componentwise shrunken estimators with typical members: Mayer and Willke's contraction estimator, Marquardt's principal component estimator, Hoerl and Kennard's ridge estimator, Liu's linear unified estimator and a discrete shrunken estimator. All estimators considered are "shorter" than the least squares estimator with respect to the Euclidean norm, biased, but insensitive to multicollinearity and admissible within the set of linear estimators with respect to unweighted squared error risk. Some behaviors of these estimators are illustrated geometrically by tracing their trajectories as functions of shrinkage factors in a two- dimensional parameter space.Item Output stabilization of semilinear parabolic systems with bounded feedback(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) El Alami, Abdessamad; Boutoulout, Ali; Yafia, Radouane; Other; OtherIn this paper, we will study the output feedback stabilization of infinite-semilinear parabolic systems evolving on a spatial domain Ω and in a subregion ω of Ω (interior to Ω or on its boundary ∂Ω). We consider the condition of admissibility and the decomposition methods technique of the state space via the spectral properties of the system. Then we apply this approach to a regional exponential stabilization problem using bounded feedback. Applications are presented.Item Influence of natural convection on stability of an inclined front propagation(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Salhi, Loubna; Rouah, Hamza; Taik, Ahmed; Other; OtherThis research work may be considered as a continuation of a series of investigations concerning the influence of natural convection on stability of reaction fronts propagation. We consider an inclined propagating polymerization front. The governing equations consist of the heat equation, the equation for the depth of conversion for one-step chemical reaction and of the Navier-Stokes equations under the Boussinesq approximation. We first perform a formal asymptotic analysis in the limit of a large activation energy to get an approximate interface problem. Then, we fulfill the linear stability analysis of the stationary solution and find the perturbation equations. A meshless collocation method based on multiquadric radial basis functions has been applied for numerical simulations. The conditions of convective instabilities obtained are in good agreement with some previous studies. This shows that the proposed approach is accurate and that it helps in describing the influence of the propagation direction on stability of polymerization fronts.Item Quasi 2-absorbing second modules(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Ansari-Toroghy, H.; Farshadifar, F.; Other; OtherIn this paper, we will introduce the notion of quasi 2-absorbing second modules over a commutative ring and obtain some basic properties of this class of modules.Item Analysis and optimal control of an HIV model with logistic growth and infected cells in eclipse phase(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) HARROUDİ, Sanaa; DANANE, Jaouad; ALLALİ, Karam; Other; OtherA mathematical model of the human immunodeficiency virus infection with logistic growth, infected cells in eclipse phase and therapy is investigated. The model includes four nonlinear differential equations describing the evolution of uninfected CD4⁺ T cells, infected CD4⁺ T cells in latent stage, productively infected CD4⁺ T cells and free virus. Two types of treatments are incorporated into the model; the purpose of the first one consists to block the viral proliferation while the role of the second is to prevent new infections. The positivity and boundedness of solutions are established. The local stability of the disease free steady state and the infection steady states are studied. An optimal control problem is proposed and investigated. Numerical simulations are performed, confirming stability of the free and endemic equilibria and illustrating the effectiveness of the two incorporated treatments via an efficient optimal control.Item Existence of solution to a nonlocal conformable fractional thermistor problem(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Ammi, Moulay Rchid Sidi; Torres, Delfim F. M.; Other; OtherWe study a nonlocal thermistor problem for fractional derivatives in the conformable sense. Classical Schauder's fixed point theorem is used to derive the existence of a tube solution.Item Assessment of supplier risk for copper procurement(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Kara, Güray; Buzdoğan-Lindenmayr, Ezgi; Selçuk--Kestel, A. Sevtap; Other; OtherProcurement risk management (PRM) requires a good understanding and assessment of all potential risks. As the procurement industry mostly functions globally and the supply--demand chain forms a dependency structure among all interested parties, the quantification of risks related to the suppliers gain importance. This study presents a systematic PRM to evaluate and quantify the risks of a commodity associated to its suppliers. The probabilistic set up using total probability theorem on the information collected using risk management tools, such as expert opinion, charts, survey and historical realizations are imposed to quantify the risks. The resulting probabilities are utilized to construct a risk matrix which illustrates the performance of each supplier at every potential risk source. An application to a copper procurement as case study is done based on the risk management process evaluation. The quantification of the supplier's risk with respect to a risk ranking illustration in copper procurement is exposed to indicate the effectiveness of the methodology and the necessity of such evaluation in decision making.Item Estimation of the location and the scale parameters of Burr Type XII distribution(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Akgül, Fatma Gül; Acıtaş, Şükrü; Şenoğlu, Birdal; İstatistik; Fen FakültesiThe aim of this paper is to estimate the location and the scale parameters of Burr Type XII distribution. For this purpose, different estimation methods, namely, maximum likelihood (ML), modified maximum likelihood (MML), least squares (LS) and method of moments (MM) are used. The performances of these estimation methods are compared via Monte-Carlo simulation study under different sample sizes and parameter settings. At the end of the study, the wind speed data set and the annual flow data sets are analyzed for illustration of the modeling performance of Burr Type XII distribution.Item On minimal free resolution of the associated graded rings of certain monomial curves : New proofs in A⁴(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Zengin, Esra Emine; Mete, Pınar; Other; OtherIn this article, even if it is known for general case in sharifan-nahandi, we give the explicit minimal free resolution of the associated graded ring of certain affine monomial curves in affine 4-space based on the standard basis theory. As a result, we give the minimal graded free resolution and the Hilbert function of the tangent cone of these families in A⁴ in the simple form according to sharifan-nahandi.Item Further study on the results of Sheremeta(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) BİSWAS, Tanmay; Other; OtherIn this paper we estimate some growth rates of composite entire and meromorphic functions in the light of their relative (p,q)-th order and relative (p,q)-th lower order which considerably extend some results of Sheremeta [14].Item Pseudo projective curvature tensor satisfying some properties on a normal paracontact metric manifold(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Yıldırım, Ümit; Atçeken, Mehmet; Dirik, Süleyman; Other; OtherIn the present paper we have studied the curvature tensor of a normal paracontact metric manifold satisfying the conditions R(ξ,X)P=0, P(ξ,X)R=0, P(ξ,X)P=0, P(ξ,X)S=0, P(ξ,X)Z=0 and pseudo projective flatness, where R, P, S and Z denote the Riemannian curvature, pseudo projective curvature, Ricci and concircular curvature tensors, respectively.Item Some Caputo K-Fractional Derivatives of Ostrowski Type Concerning (n + 1)-Differentiable Generalized Relative Semi-(r; m; p; q; h1; h2)-Preinvex Mappings(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) KASHURİ, Artion; LİKO, Rozana; Other; OtherIn this article, we first presented some integral inequalities for Gauss-Jacobi type quadrature formula involving generalized relative semi-(r;m,p,q,h₁,h₂)-preinvex mappings. And then, a new identity concerning (n+1)-differentiable mappings defined on m-invex set via Caputo k-fractional derivatives is derived. By using the notion of generalized relative semi-(r;m,p,q,h₁,h₂)-preinvexity and the obtained identity as an auxiliary result, some new estimates with respect to Ostrowski type inequalities via Caputo k-fractional derivatives are established. It is pointed out that some new special cases can be deduced from main results of the article.Item Multipoint selfadjoint quasi-differential operators for first order(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Yılmaz, Bülent; Mert, Rukiye Öztürk; Ismailov, Zameddin İ.; Fizik; Fen FakültesiIn the present paper, the aim is to described all selfadjoint extensions of the minimal operator generated by first order linear symmetric multipoint quasi-differential operator expression in the direct sum of weighted Hilbert spaces of vector-functions defined at the semi-infinite intervals by using the Calkin-Gorbachuk method. We have also examine the structure of the spectrum of such extensions.