Cilt:68 Sayı:01 (2019)

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https://dspace.ankara.edu.tr/handle/20.500.12575/75721

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A class of submersions and compatible maps in Finsler geometry
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Crasmareanu, Mircea; Other; Other
We introduce a class of submersions between two Finslerian manifolds and the class of Finsler-compatible maps which contains the previous class. Defining also the notion of stretch it follows an upper bound for the stretch of these submersions. If the support manifold for the considered Finslerian geometries is the same we introduce a new function, called conformality, as a way to measure quantitatively the difference between the given geometries.
A data science study for determining food quality: an application to wine
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Özalp, Ata Emre; Askerzade, İman; Bilgisayar Mühendisliği; Mühendislik Fakültesi
In this paper, wine quality is investigated based on physicochemical ingredients which include fixed acidity, volatile acidity, citric acid, residual sugar, chloride, free sulfur dioxide, total sulfur dioxide, density, pH, sulphate and alcohol, by ANFIS (Adaptive Neuro Fuzzy Inference System) method and by random forest algorithm which is a powerful classification algorithm. Although this study specifically investigate the relation between physicochemical ingredients and the quality of wine, the results can be adaped to determination of the quality of any food product in terms of the ingredients.
A Generalized Version of Foster and Stuart's d-statistic
(Ankara Üniversitesi, 2019-02-01) Tanıl, Halil; Other; Other
Assume that only the lists of upper k-records and lower k-records of a finite sequence are available and the existence of a monotonic trend in location is interested in. In this study, a distribution-free test based on the difference between the numbers of upper and lower k-records is proposed for this situation. The exact and asymptotic distributions of the proposed test statistic are obtained for a random continuous sequence which is independent and identically distributed (i.i.d.). Also, a comparison between the proposed test and some well-known distribution-free tests is made in terms of empirical powers.
A method for solving general singular equations and its application
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Koca, Beyaz Başak; Sadık, Nazım; Other; Other
In this paper we present a new method for solving general singular equations of normal type. As an application of this method, we give a solution for a class of convolution-type integral equations
A new family of the continuous distributions: the extended Weibull-G family
(Ankara Üniversitesi, 2019-02-01) Korkmaz, Mustafa Çagataş; Other; Other
In this study, we present a new family of continuous distributions via an extended form of the Weibull distribution. Some special members of the newly defined family are discussed and the new univariate continuous distributions are introduced. The mathematical properties are obtained for any members of the family such as expansions of the density, hazard rate function, quantile function, moments and order statistics. We obtain the distribution parameters by maximum likelihood method. The simulation study to evaluate the performance of the estimated parameters based on the selected member of the this new family is also given. The lifetime data example is discussed to illustrate the applicability of the distribution.
A new perspective of transmuted distribution
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Hameldarbandı, Monireh; Yılmaz, Mehmet; İktisat; Fen Fakültesi
Regarding 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.
A new representation of constant angle surfaces in H²×R with split quaternions
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Karakuş, Siddika Özkaldı; Other; Other
In this paper we study surfaces in H²×R for which the unit normal makes a constant angle with the R-direction. The main idea is to show that constant angle surfaces in H²×R can be obtained by split quaternion product and the matrix representations. Also we give some related examples with their projections of figures.
A Note On Statistical Approximation Properties of Complex q-Szász- Mirakjan Operators
(Ankara Üniversitesi, 2019-02-01) Arı, Didem Aydın; Other; Other
The complex q-Szász-Mirakjan operator attached to analytic functions satisfying a suitable exponential type growth condition has been studied in [14]. In this paper, we consider the A-statistical convergence of complex q-Szász- Mirakjan operator.
A Study on a Partially Null Curve in E₂⁴
(Ankara Üniversitesi, 2019-02-01) İyigün, Esen; Other; Other
In this paper, we study with Frenet equations which are given in [3] of a partially null curve in Semi- Euclidean 4-space E₂⁴ with index 2. By using the Frenet equations, we give some theorem and corollary. A characterization of a hyperbolic partially null curve in E₂⁴ is given. Additionally, we examine harmonic curvatures and curvatures of this curve in E₂⁴
Actions of internal groupoids in the category of Leibniz algebras
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Şahan, Tunçar; Erciyes, Ayhan; Other; Other
The aim of this paper is to characterize the notion of internal category (groupoid) in the category of Leibniz algebras and investigate some properties of well-known notions such as covering groupoids and groupoid operations (actions) in this category. Further, for a fixed internal groupoid G in the category of Leibniz algebras, we prove that the category of covering groupoids of G and the category of internal groupoid actions of G on Leibniz algebras are equivalent. Finally, we interpret the corresponding notion of covering groupoids in the category of crossed modules of Leibniz algebras.
Actions of soft groups
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Oğuz, Gülay; İcen, İlhan; Gürsoy, M. Habil; Zihin Engelliler Öğretmenliği; Other
The 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.
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; Other
A 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.
Approximate controllability of neutral integrodifferential inclusions via resolvent operators
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Tamilselvan, M.; Other; Other
In 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.
Approximate controllability of second-order stochastic non-autonomous integrodifferential inclusions by resolvent operators
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) NİRMALKUMAR, R.; MURUGESU, R.; Other; Other
In this paper, we formulate a set of sufficient conditions for the approximate controllability for a class of second-order stochastic non-autonomous integrodifferential inclusions in Hilbert space. We establish the results with the help of resolvent operators and Bohnenblust-Karlin's fixed point theorem is to prove the main result. An application is given to illustrate the main result.
Approximately Groups in Proximal Relator Spaces
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) İnan, Ebubekir; Other; Other
The focus of this article is on defining descriptive approximations of sets or algebraic structures in proximal relator spaces. By way of a practical application, descriptive approximately algebraic structures such as groupoids, semigroups and groups in digital images endowed with descriptive Efremovic proximity relations are introduced.
Assessment of supplier risk for copper procurement
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) Kara, Güray; Buzdoğan-Lindenmayr, Ezgi; Selçuk--Kestel, A. Sevtap; Other; Other
Procurement 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.
Asymptotic Behavior of the Non-Autonomous Reaction-Diffusion Equation with Robin Boundary Condition
(Ankara Üniversitesi, 2019-02-01) Öztürk, Eylem; Other; Other
In this paper, we investigate the long-time behavior of the time-dependent reaction-diffusion equation u_{t}-Δu+a(x)|u|^{ρ}u-b(x)|u|^{ν}u=h(x,t) with Robin boundary condition. We begin this paper with the existence and uniqueness results of the solution to the problem. For the asymptotic behavior, we firstly prove the existence of an absorbing set in W₂¹(Ω)∩L_{ρ+2}(Ω). The existence of a uniform attractor is obtained in W₂¹(Ω)∩L_{ρ+2}(Ω).
Best bound for λ- pseudo starlike functions
(Ankara Üniversitesi Fen Fakültesi, 2019-02-01) KRİSHNA, D. Vamshee; SHALİNİ, D.; Other; Other
In this paper, we obtain sharp upper bound to the second Hankel determinant for the functions belong to the class of λ- pseudo starlike functions, an interesting sub class of univalent functions defined in the open unit disc E={z:|z|<1}, using Toeplitz determinants.
Binomial-Discrete Lindley Distribution
(Ankara Üniversitesi, 2019-02-01) Kuş, Coşkun; AKdoğan, Yunus; Kınacı, İsmail; Karakaya, Kadir; ASGHARZADEH, Akbar; Other; Other
In this paper, a new discrete distribution called Binomial-Discrete Lindley (BDL) distribution is proposed by compounding the binomial and discrete Lindley distributions. Some properties of the distribution are discussed including the moment generating function, moments and hazard rate function. The estimation of distribution parameter is studied by methods of moments, proportions and maximum likelihood. A simulation study is performed to compare the performance of the different estimates in terms of bias and mean square errors. Automobile claim data applications are also presented to see that the new distribution is useful in modelling data.
Bounds for initial MacLaurin coefficients of a subclass of bi-univalent functions associated with subordination
(Ankara Üniversitesi, 2019-02-01) MOTAMEDNEZHAD, Ahmad; NOSRATİ, Shahpour; ZAKER, Sima; Other; Other
In this paper, we investigate the bounds of the coefficients for new subclasses of analytic and bi-univalent functions in the open unit disc defined by subordination. The coefficients bounds presented in this paper would generalize and improve those in related works of several earlier authors

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