Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
28 results
Search Results
Article Citation - WoS: 3Citation - Scopus: 4Stochastic bifurcation in generalized chua's circuit driven by skew-normal distributed noise(World Scientific Publishing Co. Pte Ltd, 2018) Yılmaz, Serpil; Çek, Mehmet Emre; Savacı, Ferit AcarIn this study, the stochastic phenomenological bifurcations (P-bifurcations) of generalized Chua's circuit (GCC) driven by skew-normal distributed noise have been investigated by numerically obtaining the stationary distributions of the stochastic responses. The noise intensity and/or skewness parameters of skew-normal distributed noise have been chosen as the bifurcation parameters to change the structure of the stochastic attractor. While the number of breakpoints in the piecewise-linear characteristics of the GCC are fixed, it has been observed that the number of scrolls have been changed by tuning the noise intensity and the skewness parameter of the skew-normal distributed noise.Article Citation - WoS: 22Citation - Scopus: 24Are There Really Conformal Frames? Uniqueness of Affine Inflation(World Scientific Publishing Co. Pte Ltd, 2018) Azri, HemzaHere, we concisely review the nonminimal coupling dynamics of a single scalar field in the context of purely affine gravity and extend the study to multifield dynamics. The coupling is performed via an affine connection and its associated curvature without referring to any metric tensor. The latter arises a posteriori and it may gain an emergent character like the scale of gravity. What is remarkable in affine gravity is the transition from nonminimal to minimal couplings which is realized by only field redefinition of the scalar fields. Consequently, the inflationary models gain a unique description in this context where the observed parameters, like the scalar tilt and the tensor-to-scalar ratio, are invariant under field reparametrization. Overall, gravity in its affine approach is expected to reveal interesting and rich phenomenology in cosmology and astroparticle physics.Conference Object Stress-Energy Connection: Degravitating the Vacuum Energy(World Scientific Publishing Co. Pte Ltd, 2013) Demir, Durmuş AliThis talk summarizes recent studies on the gravitational properties of vacuum energy in a non-Riemannian geometry formed by the stress-energy tensor of vacuum, matter and radiation. Postulating that the gravitational effects of matter and radiation can be formulated by an appropriate modification of the spacetime connection, we obtain varied geometro-dynamical equations which properly comprise the usual gravitational field equations with, however, Planck-suppressed, non-local, higher-dimensional additional terms. The prime novelty brought about by the formalism is that, the vacuum energy does act not as the cosmological constant but as the source of the gravitational constant. The formalism thus deafens the cosmological constant problem by channeling vacuum energy to gravitational constant. Nevertheless, quantum gravitational effects, if any, restore the problem via the graviton and graviton-matter loops, and the mechanism proposed here falls short of taming such contributions to cosmological constant.Article Citation - WoS: 7Citation - Scopus: 9Input Contract Testing of Graphical User Interfaces(World Scientific Publishing Co. Pte Ltd, 2016) Tuğlular, Tuğkan; Belli, Fevzi; Linschulte, MichaelUser inputs are critical for the security, safety, and reliability of software systems. This paper proposes a new concept called user input contracts, which is an integral part of a design-by-contract supplemented development process, and a model-based testing approach to detect violations of user input contracts. The approach generates test cases from an input contract integrated with graph-based model of user interface specification and applies them to the system under consideration. The paper presents a proof-of-concept tool that has been developed and used to validate the approach by experiments. The experiments are conducted on a web-based system for marketing tourist services to analyze input robustness of system under consideration with respect to user input contracts.Article Citation - WoS: 4Citation - Scopus: 4Bayesian Stable Mixture Model of State Densities of Generalized Chua's Circuit(World Scientific Publishing Co. Pte Ltd, 2015) Savacı, Ferit Acar; Yılmaz, SerpilIn this paper, the probability density functions (PDFs) of the states of Generalized Chua's Circuit (GCC) have been modeled by Finite Mixture α-Stable (FMαS) distributions which is a Bayesian mixture model of α-stable distributions and it provides semiparametric characterization for the distributions of multiscroll chaotic attractors. Fully Bayesian approach has been applied to estimate the mixture parameters of multimodal distributions corresponding to the multiscroll chaotic attractors.Article Citation - WoS: 1Citation - Scopus: 1Softly Fine-Tuned Standard Model and the Scale of Inflation(World Scientific Publishing Co. Pte Ltd, 2015) Korutlu, BesteThe direct coupling between the Higgs field and the spacetime curvature, if finely tuned, is known to stabilize the Higgs boson mass. The fine-tuning is soft because the Standard Model (SM) parameters are subject to no fine-tuning thanks to their independence from the Higgs-curvature coupling. This soft fine-tuning leaves behind a large vacuum energy ∝ ΛUV 4 which inflates the Universe with a Hubble rate ∝ ΛUV, UV being the SM ultraviolet (UV) boundary. This means that the tensor-to-scalar ratio inferred from cosmic microwave background polarization measurements by BICEP2, Planck and others lead to the determination of UV. The exit from the inflationary phase, as usual, is accomplished via decays of the vacuum energy. Here, we show that, identification of UV with the inflaton, as a sliding UV scale upon the SM, respects the soft fine-tuning constraint and does not disrupt the stability of the SM Higgs boson.Article On pseudo semisimple rings(World Scientific Publishing Co. Pte Ltd, 2013) Büyükaşık, Engin; Mohamed, Saad H.; Mutlu, HaticeA necessary and sufficient condition is obtained for a right pseudo semisimple ring to be left pseudo semisimple. It is proved that a right pseudo semisimple ring is an internal exchange ring. It is also proved that a right and left pseudo semisimple ring is an SSP ringArticle Citation - WoS: 5Citation - Scopus: 3Rings Over Which Flat Covers of Simple Modules Are Projective(World Scientific Publishing Co. Pte Ltd, 2012) Büyükaşık, EnginLet R be a ring with identity. We prove that, the flat cover of any simple right R-module is projective if and only if R is semilocal and J(R) is cotorsion if and only if R is semilocal and any indecomposable flat right R-module with unique maximal submodule is projective.Article Citation - WoS: 45Citation - Scopus: 48Semiclassical Black Holes With Large N Rescaling and Information Loss Problem(World Scientific Publishing Co. Pte Ltd, 2011) Yeom, Dong-Han; Zoe, HeeseungWe consider semiclassical black holes and related rescalings with N massless fields. For a given semiclassical solution of an N = 1 universe, we can find other solution of a large N universe by the rescaling. After the rescaling, any curvature quantity takes a sufficiently small value without changing its causal structure. Via the rescaling, we argue that black hole complementarity for semiclassical black holes cannot provide a fundamental resolution of the information loss problem, and the violation of black hole complementarity requires sufficiently reasonable amounts of N. Such N might be realized from some string inspired models. Finally, we claim that any fundamental resolution of the information loss problem should resolve the problem of the singularity.Article Citation - WoS: 14Citation - Scopus: 16Random Communication System Based on Skewed Alpha-Stable Levy Noise Shift Keying(World Scientific Publishing Co. Pte Ltd, 2017) Ahmed, Areeb; Savacı, Ferit AcarThe digital communication system is based on the skewed alpha-stable (α-stable) noise sequence which is chosen as the random carrier to modulate the binary message at the transmitter side. Antipodal characteristic of the skew parameter beta (β) is exploited for decoding information at the receiver side to obtain a secure communication system. A fast estimator used in this paper is based on Modified Extreme Value Method (MEVM) to extract the binary message from the signal received through the Additive White Gaussian Noise (AWGN) channel. Our proposed receiver is achieving better bit error rate (BER) versus Mixed Signal to Noise Ratio (MSNR) than previously introduced receivers which are based on Sinc and Logarithmic estimators. MEVM estimator is indeed less complex compared to the Sinc and Logarithmic estimators and hence more fast. Additionally, the criterion to measure the security level of random communication system, which is based on α-stable noise sequence, has also been introduced.
- «
- 1 (current)
- 2
- 3
- »