Browsing by Subject "Comparative analysis"

Now showing 1 - 4 of 4

Open Access
Bias in bonding behavior among boron, carbon, and nitrogen atoms in ion implanted a-BN, a-BC, and diamond like carbon films
(2011) Genisel, M. F.; Uddin, M. N.; Say, Z.; Kulakci, M.; Turan, R.; Gulseren, O.; Bengu, E.
In this study, we implanted Nþ and Nþ 2 ions into sputter deposited amorphous boron carbide (a-BC) and diamond like carbon (DLC) thin films in an effort to understand the chemical bonding involved and investigate possible phase separation routes in boron carbon nitride (BCN) films. In addition, we investigated the effect of implanted Cþ ions in sputter deposited amorphous boron nitride (a-BN) films. Implanted ion energies for all ion species were set at 40 KeV. Implanted films were then analyzed using x-ray photoelectron spectroscopy (XPS). The changes in the chemical composition and bonding chemistry due to ion-implantation were examined at different depths of the films using sequential ion-beam etching and high resolution XPS analysis cycles. A comparative analysis has been made with the results from sputter deposited BCN films suggesting that implanted nitrogen and carbon atoms behaved very similar to nitrogen and carbon atoms in sputter deposited BCN films. We found that implanted nitrogen atoms would prefer bonding to carbon atoms in the films only if there is no boron atom in the vicinity or after all available boron atoms have been saturated with nitrogen. Implanted carbon atoms also preferred to either bond with available boron atoms or, more likely bonded with other implanted carbon atoms. These results were also supported by ab-initio density functional theory calculations which indicated that carbon-carbon bonds were energetically preferable to carbon-boron and carbon-nitrogen bonds.
Open Access
A comparative analysis of critical infrastructure cyber security policies: best practices from the US, EU and Turkey
(2020-06) Düveroğlu, Efe
Critical infrastructures are the physical and virtual systems forming the basis of modern societies and they are essential in ensuring national prosperity. Even though the importance of such infrastructures could not be grasped by states and international organizations in the beginning, an increasing number of cyber threats targeting critical infrastructure systems is becoming the reason behind the acceleration of the engagement of critical infrastructure protection as an agenda item as seen in the United States and the European Union. In Turkey, the field of critical infrastructure policy is still in its infancy. This thesis compares the developments of critical infrastructure security in the United States, the European Union and Turkey through an investigation of definitional, legal, institutional and economic practices relating to critical infrastructure. While doing so, this thesis aims to reveal Turkey's current status in the field of critical infrastructure protection. In this regard, this thesis also analyzes how successful critical infrastructure security policies have been in Turkey. According to the findings of this thesis, Turkey is far behind the United States and the European Union in the field as a result of institutional and legal gaps that prevent the development of infrastructure protection. The policy initiatives which Turkey has to pursue are also discussed in the thesis.
Open Access
Influence of phase function on modeled optical response of nanoparticle-labeled epithelial tissues
(2011) Cihan, C.; Arifler, D.
Metal nanoparticles can be functionalized with biomolecules to selectively localize in precancerous tissues and can act as optical contrast enhancers for reflectance-based diagnosis of epithelial precancer. We carry out Monte Carlo (MC) simulations to analyze photon propagation through nanoparticle-labeled tissues and to reveal the importance of using a proper form of phase function for modeling purposes. We first employ modified phase functions generated with a weighting scheme that accounts for the relative scattering strengths of unlabeled tissue and nanoparticles. To present a comparative analysis, we repeat ourMCsimulations with simplified functions that only approximate the angular scattering properties of labeled tissues. The results obtained for common optical sensor geometries and biologically relevant labeling schemes indicate that the exact form of the phase function used as model input plays an important role in determining the reflectance response and approximating functions often prove inadequate in predicting the extent of contrast enhancement due to labeling. Detected reflectance intensities computed with different phase functions can differ up to ̃60% and such a significant deviation may even alter the perceived contrast profile. These results need to be taken into account when developing photon propagation models to assess the diagnostic potential of nanoparticle-enhanced optical measurements. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).
Open Access
Overview
(CEPR, 2005) Togan, Sübidey; Hoekman, B.; Togan, Sübidey; Hoekman, B.