Ünal, Bernis
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Ünal, B
Bernis, Unal
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Unal, Bernis
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Bernis, Unal
Bernis, Ünal
Ünal,B.
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Unal, Bernis
Ü.,Bernis
Ünal, Bernis
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Job Title
Öğretim Görevlisi
Email Address
bernis.unal@atilim.edu.tr
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
8
Articles
7
Citation Count
301
Supervised Theses
0
8 results
Scholarly Output Search Results
Now showing 1 - 8 of 8
Article Citation Count: 41On a differential equation characterizing Euclidean spheres(Academic Press inc Elsevier Science, 2003) Ünal, Bernis; Kupeli, DN; Ünal, B; Department of Modern LanguagesA characterization of Euclidean spheres out of complete Riemannian manifolds is made by certain vector fields on complete Riemannian manifolds satisfying a partial differential equation on vector fields. (C) 2003 Elsevier Inc. All rights reserved.Article Citation Count: 68Curvature of multiply warped products(Elsevier, 2005) Ünal, Bernis; Ünal, B; Department of Modern LanguagesIn this paper, we study Ricci-flat and Einstein-Lorentzian multiply warped products. We also consider the case of having constant scalar curvatures for this class of warped products. Finally, after we introduce a new class of space-times called as generalized Kasner space-times, we apply our results to this kind of space-times as well as other relativistic space-times, i.e., Reissner-Nordstrom, Kasner space-times, Banados-Teitelboim-Zanelli and de Sitter black hole solutions. (c) 2004 Elsevier B.V. All rights reserved.Conference Object Citation Count: 0The effect of split attention in surgical education(Springer Verlag, 2014) Özçelik, Erol; Ünal, Bernis; Sengul,G.; Tuner,E.; Şengül, Gökhan; Department of Modern Languages; Computer EngineeringSurgical education through simulation is an important area to improve the level of education and to decrease the risks, ethical considerations and cost of the educational environments. In the literature there are several studies conducted to better understand the effect of these simulation environments on learning. However among those studies the human-computer interaction point of view is very limited. Surgeons need to look at radiological images such as magnetic resonance images (MRI) to be sure about the location of the patient's tumor during a surgical operation. Thus, they go back and forth between physically separated places (e.g. the operating table and light screen display for MRI volume sets). This study is conducted to investigate the effect of presenting different information sources in close proximity on human performance in surgical education. For this purpose, we have developed a surgical education simulation scenario which is controlled by a haptic interface. To better understand the effect of split attention in surgical education, an experimental study is conducted with 27 subjects. The descriptive results of study show that even the integrated group performed the tasks with a higher accuracy level (by traveling less distance, entering less wrong directions and hitting less walls), the results are not statistically significant. Accordingly, even there are some evidences about the effect of split attention on surgical simulation environments, the results of this study need to be validated by controlling students' skill levels on controlling the haptic devices and 2D/3D space perception skills. The results of this study may guide the system developers to better design the HCI interface of their designs especially for the area of surgical simulation. © 2014 Springer International Publishing.Article Citation Count: 17Special standard static space-times(Pergamon-elsevier Science Ltd, 2004) Ünal, Bernis; Ünal, B; Department of Modern LanguagesEssentially, some conditions for the Riemannian factor and the warping function of a standard static space-time are obtained in order to guarantee that no nontrivial warping function on the Riemannian factor can make the standard static space-time Einstein. (C) 2004 Elsevier Ltd. All rights reserved.Article Citation Count: 65Doubly warped products(Elsevier Science Bv, 2001) Ünal, Bernis; Department of Modern LanguagesIn this paper we study geodesic completeness of Riemannian doubly warped products and Lorentzian doubly warped products. We give necessary conditions for generalized Robertson-Walker spacetimes with doubly warped product spacial parts to be globally hyperbolic. We also state some results about killing and conformal vector fields of doubly warped products.Article Citation Count: 57A curvature condition for a twisted product to be a warped product(Springer-verlag, 2001) Ünal, Bernis; García-Río, E; Kupeli, DN; Ünal, B; Department of Modern LanguagesIt is shown that a mixed Ricci-flat twisted product semi-Riemannian manifold can be expressed as a warped product semi-Riemannian manifold. Asa consequence, any Einstein twisted product semi-Riemannian manifold is in fact, a warped product serni-Riemannian manifold.Article Citation Count: 29Characterizing specific Riemannian manifolds by differential equations(Springer, 2003) Ünal, Bernis; García-Río, E; Kupeli, DN; Ünal, B; Department of Modern LanguagesSome characterizations of certain rank-one symmetric Riemannian manifolds by the existence of nontrivial solutions to certain partial differential equations on Riemannian manifolds are surveyed.Article Citation Count: 24Geodesic structure of standard static space-times(Elsevier Science Bv, 2003) Ünal, Bernis; Ünal, B; Department of Modern LanguagesThe geodesic structure of standard static space-times is studied and conditions are found which imply nonreturning and pseudoconvex geodesic systems. As a consequence, it is shown that if the Riemannian factor manifold F satisfies the nonreturning property and has a pseudoconvex geodesic system and if the warping function f : F --> (0, infinity) is bounded above then the standard static space-time (f)(a, b) x F is geodesically connected. (C) 2002 Elsevier Science B.V. All rights reserved.
