Bilgisayar Bilimleri Fakültesi

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Comparative assessment of smooth and non-smooth optimization solvers in HANSO software
(Balikesir University, 2022) Tor, Ali Hakan; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü; Tor, Ali Hakan
The aim of this study is to compare the performance of smooth and nonsmooth optimization solvers from HANSO (Hybrid Algorithm for Nonsmooth Optimization) software. The smooth optimization solver is the implementation of the Broyden-Fletcher-Goldfarb-Shanno (BFGS) method and the nonsmooth optimization solver is the Hybrid Algorithm for Nonsmooth Optimization. More precisely, the nonsmooth optimization algorithm is the combination of the BFGS and the Gradient Sampling Algorithm (GSA). We use well-known collection of academic test problems for nonsmooth optimization containing both convex and nonconvex problems. The motivation for this research is the importance of the comparative assessment of smooth optimization methods for solving nonsmooth optimization problems. This assessment will demonstrate how successful is the BFGS method for solving nonsmooth optimization problems in comparison with the nonsmooth optimization solver from HANSO. Performance profiles using the number iterations, the number of function evaluations and the number of subgradient evaluations are used to compare solvers. © 2021 Balikesir University. All rights reserved.
Existence of positive solutions for nonlinear multipoint p-Laplacian dynamic equations on time scales
(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, ATATURK BULVARI NO 221, KAVAKLIDERE, TR-06100 ANKARA, TURKEY, 2020) Dogan, Abdulkadir; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü
In this paper, we investigate the existence of positive solutions for nonlinear multipoint boundary value problems for p-Laplacian dynamic equations on time scales with the delta derivative of the nonlinear term. Sufficient assumptions are obtained for existence of at least twin or arbitrary even positive solutions to some boundary value problems. Our results are achieved by appealing to the fixed point theorems of Avery-Henderson. As an application, an example to demonstrate our results is given.
Multiple positive solutions of nonlinear m-point dynamic equations for p-Laplacian on time scales
(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, ATATURK BULVARI NO 221, KAVAKLIDERE, TR-06100 ANKARA, TURKEY, 2016) Dogan, Abdulkadir; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü; Dogan, Abdulkadir
In this paper, we study the existence of positive solutions of a nonlinear m-point p-Laplacian dynamic equation (phi(p) (x(Delta)(t)))(del) w(t)f (t,x(t), x(Delta)(t)) = 0, t(1) < m-1 X(ti) - B-0 (Sigma m-1 i=2 a(i)x(Delta)(t(i))) = 0, x(Delta) (tm) = 0, or x(Delta)(t(1)) - 0, x(t(m)) + B-1(Sigma m-1 i=2 b(i)s(Delta)(t(i))) -0, where phi(p)(s) =vertical bar s vertical bar(P-2) s, p > 1. Sufficient conditions for the existence of at least three positive solutions of the problem are obtained by using a fixed point theorem. The interesting point is the nonlinear term f is involved with the first order derivative explicitly. As an application, an example is given to illustrate the result.
On the existence of positive solutions for the second-order boundary value problem
(PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND, 2015) Dogan, Abdulkadir; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü; Dogan, Abdulkadir
This paper is concerned with the existence of positive solutions to a second order boundary value problem. By imposing growth conditions on f and using a generalization of the Leggett-Williams fixed point theorem, we prove the existence of at least three symmetric positive solutions. (C) 2015 Elsevier Ltd. All rights reserved.
On the Existence of Positive Solutions for the Time-Scale Dynamic Equations on Infinite Intervals
(Springer, 2020) Dogan A.; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü
This paper investigates the existence of positive solutions to time-scale boundary value problems on infinite intervals. By applying the Leggett-Williams fixed point theorem in a cone, some new results for the existence of at least three positive solutions of boundary value problems are found. With infinite intervals, the theorem can be used to prove the existence of solutions of boundary value problems for nonlinear dynamic equations dependence on the delta derivative explicitly. Our results are new for the special cases of difference equations and differential equations as well as in the general time scale setting.
POSITIVE SOLUTIONS OF THE p-LAPLACIAN DYNAMIC EQUATIONS ON TIME SCALES WITH SIGN CHANGING NONLINEARITY
(TEXAS STATE UNIV, 601 UNIVERSTITY DRIVE, SAN MARCOS, TX 78666 USA, 2018) Dogan, Abdulkadir; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü; Dogan, Abdulkadir
This article concerns the existence of positive solutions for p-Laplacian boundary value problem on time scales. By applying fixed point index we obtain the existence of solutions. Emphasis is put on the fact that the nonlinear term is allowed to change sign. An example illustrates our results.
ROI Detection in Mammogram Images using Wavelet-Based Haralick and HOG Features
(IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA, 2018) Tasdemir, Sena Busra Yengec; Tasdemir, Kasim; Aydin, Zafer; 0000-0003-4542-2728; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü
Digital mammography is a widespread medical imaging technique that is used for early detection and diagnosis of breast cancer. Detecting the region of interest (ROI) helps to locate the abnormal areas, which may be analyzed further by a radiologist or a CAD system. In this paper, a new classification method is proposed for ROI detection in mammography images. Features are extracted using Wavelet transform, Haralick and HOG descriptors. To reduce the number of dimensions and eliminate irrelevant features, a wrapper-based feature selection method is implemented. Several feature extraction methods and machine learning classifiers are compared by performing a leave-one-image-out cross-validation experiment on a difficult dataset. The proposed feature extraction method provides the best accuracy of 87.5% and the second-best area under curve (AUC) score of 84% when employed in a random forest classifier.
TRIPLE POSITIVE SOLUTIONS FOR m-POINT BOUNDARY-VALUE PROBLEMS OF DYNAMIC EQUATIONS ON TIME SCALES WITH p-LAPLACIAN
(TEXAS STATE UNIV, 601 UNIVERSTITY DRIVE, SAN MARCOS, TX 78666 USA, 2015) Dogan, Abdulkadir; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü; Dogan, Abdulkadir
In this article we study the existence of positive solutions for m-point dynamic equation on time scales with p-Laplacian. We prove that the boundary-value problem has at least three positive solutions by applying the five functionals fixed-point theorem. An example demonstrates the main results.

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