Browsing by Author "Özdoǧan, C."

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About Nanometer Sized Analogues of Basic Electronic and Optical Components
(Ieee, 2008) Quandt, A.; Özdoǧan, C.; Ferrari, M.; Speranza, G.; Oezdogan, Cem
We discuss a downsizing of optical components into the nanometer range. It presupposes the substitution of photons by ballistic electrons, but it also requires a simple and robust concept to assemble the analogues of basic electronic and optical components on such a tiny length scale. Here, one of the most promising candidate schemes employs graphene as a basic nanosubstrate. We elucidate the suggested behaviour of graphene as an electronic metamaterial [1], and show that other desired electronic or optical functionalities may be obtained through a patterning with sub-nanometer sized boron clusters [2]. © 2008 IEEE.
Citation - Scopus: 1
Fragmentation and Coulomb Explosion of Multicharged Small Boron Clusters
(2012) Tas, M.; Akman, N.; Özdoǧan, C.; Boustani, I.
We extensively study the fragmentation and Coulomb explosion of multiply charged small boron clusters B n (n=2-13), where n is the cluster size. Our calculations are based on ab initio quantum-chemistry methods. Highly charged unstable clusters dissociate spontaneously into several neutral or charged fragments, and large amounts of energy are produced, depending on the charge of the parent cluster. We argue that this mechanism makes boron clusters a clean, safe, and cheap energetic material. © 2012 American Physical Society.
Citation - Scopus: 10
O(N) Algorithms in Tight-Binding Molecular-Dynamics Simulations of the Electronic Structure of Carbon Nanotubes
(2003) Dereli, G.; Özdoǧan, C.
The O(N) and parallelization techniques have been successfully applied in tight-binding moleculardynamics simulations of single-walled carbon nanotubes (SWNT's) of various chiralities. The accuracy of the O(N) description is found to be enhanced by the use of basis functions of neighboring atoms (buffer). The importance of buffer size in evaluating the simulation time, total energy, and force values together with electronic temperature has been shown. Finally, through the local density of state results, the metallic and semiconducting behavior of (10 X 10) armchair and (17 X 0) zigzag SWNT's, respectively, has been demonstrated.
Citation - Scopus: 4
Parallel Data Reduction Techniques for Big Datasets
(IGI Global, 2016) Yıldırım, A.A.; Özdoǧan, C.; Watson, D.
Data reduction is perhaps the most critical component in retrieving information from big data (i.e., petascale-sized data) in many data-mining processes. The central issue of these data reduction techniques is to save time and bandwidth in enabling the user to deal with larger datasets even in minimal resource environments, such as in desktop or small cluster systems. In this chapter, the authors examine the motivations behind why these reduction techniques are important in the analysis of big datasets. Then they present several basic reduction techniques in detail, stressing the advantages and disadvantages of each. The authors also consider signal processing techniques for mining big data by the use of discrete wavelet transformation and server-side data reduction techniques. Lastly, they include a general discussion on parallel algorithms for data reduction, with special emphasis given to parallel waveletbased multi-resolution data reduction techniques on distributed memory systems using MPI and shared memory architectures on GPUs along with a demonstration of the improvement of performance and scalability for one case study. © 2025 Elsevier B.V., All rights reserved.
Citation - WoS: 9
Citation - Scopus: 11
Thermal Stability of Metallic Single-Walled Carbon Nanotubes: an O(N) Tight-Binding Molecular Dynamics Simulation Study
(Iop Publishing Ltd, 2007) Suengue, B.; Oezdogan, C.; Dereli, G.; Süngü, B.; Özdoǧan, C.
Order(N) tight-binding molecular dynamics (TBMD) simulations are performed to investigate the thermal stability of ( 10, 10) metallic single-walled carbon nanotubes (SWCNTs). Periodic boundary conditions (PBCs) are applied in the axial direction. The velocity Verlet algorithm along with the canonical ensemble molecular dynamics (NVT) is used to simulate the tubes at the targeted temperatures. The effects of slow and rapid temperature increases on the physical characteristics, structural stability and the energetics of the tube are investigated and compared. Simulations are carried out starting from room temperature and the temperature is raised in steps of 300 K. The stability of the simulated metallic SWCNT is examined at each step before it is heated to higher temperatures. The first indication of structural deformation is observed at 600 K. For higher heat treatments the deformations are more pronounced and the bond-breaking temperature is reached around 2500 K. Gradual ( slow) heating and thermal equilibrium ( fast heating) methods give the value of radial thermal expansion coefficient in the temperature range between 300 and 600 K as 0.31 x 10(-5) and 0.089 x 10(-5) K-1, respectively. After 600 K, both methods give the same value of 0.089 x 10(-5) K-1. The ratio of the total energy per atom with respect to temperature is found to be 3 x 10(-4) eV K-1.