Browsing by Subject "Astrophysics"

Now showing 1 - 3 of 3

Open Access
A color-based face tracking algorithm for enhancing interaction with mobile devices
(Springer, 2010-05) Bulbul, A.; Cipiloglu, Z.; Capin, T.
A color-based face tracking algorithm is proposed to be used as a human-computer interaction tool on mobile devices. The solution provides a natural means of interaction enabling a motion parallax effect in applications. The algorithm considers the characteristics of mobile useconstrained computational resources and varying environmental conditions. The solution is based on color comparisons and works on images gathered from the front camera of a device. In addition to color comparisons, the coherency of the facial pixels is considered in the algorithm. Several applications are also demonstrated in this work, which use the face position to determine the viewpoint in a virtual scene, or for browsing large images. The accuracy of the system is tested under different environmental conditions such as lighting and background, and the performance of the system is measured in different types of mobile devices. According to these measurements the system allows for accurate (7% RMS error) face tracking in real time (20-100 fps). © Springer-Verlag 2010.
Open Access
Fast multipole methods in service of various scientific disciplines
(IEEE, 2014) Gürel, Levent
For more than two decades, several forms of fast multipole methods have been extremely successful in various scientific disciplines. Reduced complexity solutions are obtained for solving different forms of equations that are derived from Maxwell's equations, such as Helmholtz's equation for electrodynamics and Laplace's equation for electrostatics. Fast multipole solvers are developed for and applied to the integral equations derived from Helmholtz's and Laplace's equations. Fast multipole solvers are kernel-dependent techniques, i.e., they rely on certain analytical properties of the integral-equation kernels, such as diagonalizability. Electromagnetics is not the only discipline benefiting from the fast multipole methods; a plethora of computations in various disciplines, such as the solution of Schroedinger's equation in quantum mechanics and the calculation of gravitational force in astrophysics, to name a few, exploit the reduced-complexity nature of the fast multipole methods. Acoustics, molecular dynamics, structural mechanics, and fluid dynamics can be mentioned as other disciplines served by the fast multipole methods. © 2014 IEEE.
Open Access
Non-Einsteinian black holes in generic 3D gravity theories
(American Physical Society, 2019) Gürses, Metin; Şişman, T. Ç.; Tekin, B.
The Bañados-Teitelboim-Zanelli (BTZ) black hole metric solves the three-dimensional Einstein’s theory with a negative cosmological constant as well as all the generic higher derivative gravity theories based on the metric; as such it is a universal solution. Here, we find, in all generic higher derivative gravity theories, new universal non-Einsteinian solutions obtained as Kerr-Schild type deformations of the BTZ black hole. Among these, the deformed nonextremal BTZ black hole loses its event horizon while the deformed extremal one remains intact as a black hole in any generic gravity theory.