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Article Citation - WoS: 39Citation - Scopus: 49Usability and Accessibility Evaluation of Libyan Government Websites(Springer Heidelberg, 2019) Karaim, Nuha Awlad; Inal, YavuzThe aim of this study was to evaluate the usability and accessibility of Libyan government websites. A total of ten government websites in Libya were analyzed according to the criteria of the Web Content Accessibility Guidelines version 2.0, and one of them was selected for further analysis based on usability criteria. The results showed that the evaluated website had significant number of usability problems. More than half of the usability problems were rated as major and catastrophic. Visibility of system status, user control and freedom, and user help recognize, diagnose, and recover from errors were the most violated heuristic items. All Libyan government websites did not pass accessibility evaluation using the AChecker tool with the exception of the website for Management of Scholarships, and all failed using the TAW tool. Providing text alternatives for each non-text element was the most frequently violated success criterion for Libyan government websites.Article Citation - WoS: 2Citation - Scopus: 2The Impact of the Limit q-durrmeyer Operator on Continuous Functions(Springer Heidelberg, 2024) Yilmaz, Ovgu Gurel; Ostrovska, Sofiya; Turan, MehmetThe limit q-Durrmeyer operator, D-infinity,D-q, was introduced and its approximation properties were investigated by Gupta (Appl. Math. Comput. 197(1):172-178, 2008) during a study of q-analogues for the Bernstein-Durrmeyer operator. In the present work, this operator is investigated from a different perspective. More precisely, the growth estimates are derived for the entire functions comprising the range of D-infinity,D-q. The interrelation between the analytic properties of a function f and the rate of growth for D(infinity,q)f are established, and the sharpness of the obtained results are demonstrated.Article Citation - WoS: 1Citation - Scopus: 1Re-Examining the Real Interest Rate Parity Hypothesis Under Temporary Gradual Breaks and Nonlinear Convergence(Springer Heidelberg, 2023) Hasanov, Mubariz; Omay, Tolga; Abioglu, VasifThis paper investigates the real interest parity hypothesis by testing stationarity of real interest rate differentials for 52 countries with respect to the USA. Taking account of the fact that both asymmetric adjustment and gradual temporary breaks may better characterize the dynamics of real interest rate differentials, we propose a new test that allows for two temporary shifts together with asymmetric adjustment towards the equilibrium. We employ the newly proposed test procedure along with the conventional ADF test as well as nonlinear KSS and OSH tests to examine stationarity of real interest rate differentials. Among the main results, we find that the newly proposed unit root test procedure highly outperforms the existing unit root tests in terms of rejecting the null hypothesis of unit root. Our results suggest that real interest rate differentials can be characterized by a stationary process with asymmetric adjustment around gradual and temporary shifts of mean.Article Citation - WoS: 9Citation - Scopus: 10Influence of Cement Replacement by Calcinated Kaolinitic and Montmorillonite Clays on the Properties of Mortars(Springer Heidelberg, 2023) Al-Noaimat, Yazeed A. A.; Akis, TolgaThis study aims to investigate the decomposition and pozzolanic reactivity of two different clays (kaolinitic and montmorillonite) from different origins and to determine their effects after calcination on the properties of cement mortars when used to replace Portland cement partially. Mineralogical and chemical compositions of the clay samples were determined using XRD (X-ray Diffractometer) and XRF (X-ray Fluorescence) tests, respectively. TG-DTA (Thermogravimetry-Differential Thermal Analyses) was used to determine the temperature profiles and the burning temperatures of the clays. The density and fineness of the burnt clays were also determined. In order to investigate the optimum material properties, different burning temperatures and replacement levels were considered. It was found that for all temperatures, the two burnt clays possess good pozzolanic activity. The highest compressive strength and lowest water absorption capacity were achieved when the clay determined as kaolinitic was burned at 700 & DEG;C and with 10% replacement level. While for the clay determined as montmorillonite, the optimum properties were obtained at 700 & DEG;C with a 20% substitution level. Kaolinite had better pozzolanic reactivity than montmorillonite, achieving higher strength performance with lower water absorption when partially replaced with cement. Moreover, it had compressive strength values even higher than plain cement.Article Citation - WoS: 159Citation - Scopus: 164Economic Policy Uncertainty, Energy Consumption and Carbon Emissions in G7 Countries: Evidence From a Panel Granger Causality Analysis(Springer Heidelberg, 2020) Pirgaip, Burak; Dincergok, BurcuWe investigate the causal relationship between economic policy uncertainty (EPU) and energy consumption and carbon (CO2) emissions in G7 countries. We employ a bootstrap panel Granger causality test developed by Konya (Econ Model 23:978-992, 2006), using a yearly data set spanning from 1998 to 2018. Our test results provide significant support for a unidirectional causality running from EPU to energy consumption in Japan; from EPU to CO2 emissions in the USA and Germany; and from EPU to both energy consumption and CO2 emissions in Canada. In Italy, causality runs from CO2 emissions to EPU, but a bidirectional causality between EPU and energy consumption exists as well. We also explore a unidirectional causality that runs from energy consumption to CO2 in the USA. Based on the overall findings, we draw important implications for policymakers and we strongly recommend for G7 countries to take into account possible negative effects of EPU on energy conservation policies, which should be embarked upon to reduce energy consumption and CO2 emissions, as committed in their recent climate mandate.Article Citation - WoS: 4Citation - Scopus: 4Physical Characterization of Thermally Evaporated Sn-Sb Thin Films for Solar Cell Applications(Springer Heidelberg, 2023) Bektas, Tunc; Surucu, Ozge; Terlemezoglu, Makbule; Parlak, MehmetThe substitution of Sb in binary SnSe structure may lead to tailoring the physical properties of both SnSe and SbSe, promising absorber layers for thin film solar cells. The resulting Sn-Sb-Se structure could be an outstanding material for photovoltaic applications. In this study, Sn-Sb-Se thin films were deposited by thermal evaporation, and the effect of annealing on the films' structural, optical, and electrical properties were reported. XRD measurement shows that annealing at 300 degrees C yields the best crystalline quality, and structural parameters were calculated using XRD data. SEM and AFM measurements indicate deformation in the film surface after annealing at 400 degrees C. UV-Vis spectroscopy measurement provides a high absorption coefficient which indicates a direct band gap. The band gap and activation energies of the as-grown sample were found as 1.59 eV and 106.1 meV, respectively. The results of SEM, AFM, XRD, Raman, UV-Vis spectroscopy and temperature-dependent photoconductivity measurements were discussed throughout the paper.Article Citation - WoS: 2Citation - Scopus: 2Optical Characterization of Nabi(moo4)2< Crystal by Spectroscopic Ellipsometry(Springer Heidelberg, 2024) Guler, I.; Isik, M.; Gasanly, N. M.The compound NaBi(MoO4)(2) has garnered significant interest in optoelectronic fields. This study employs spectroscopic ellipsometry to thoroughly examine the linear and nonlinear optical characteristics of NaBi(MoO4)(2) crystals, offering detailed insights into their optical behavior. Our investigation presents a precise method for discerning the crystal's spectral features, revealing the spectral variations of key optical parameters such as refractive index, extinction coefficient, dielectric function, and absorption coefficient within the 1.2-5.0 eV range. Through analysis, we determined optical attributes including bandgap energy, critical point energy, and single oscillator parameters. Additionally, we explored the nonlinear optical properties of NaBi(MoO4)(2), unveiling potential applications such as optoelectronic devices, frequency conversion, and optical sensors. This study enhances comprehension of optical properties of NaBi(MoO4)(2), underscoring its significance in future optical and electronic advancements.Article Citation - WoS: 3Citation - Scopus: 6A Discrete Optimality System for an Optimal Harvesting Problem(Springer Heidelberg, 2017) Bakan, Hacer Oz; Yilmaz, Fikriye; Weber, Gerhard-WilhelmIn this paper, we obtain the discrete optimality system of an optimal harvesting problem. While maximizing a combination of the total expected utility of the consumption and of the terminal size of a population, as a dynamic constraint, we assume that the density of the population is modeled by a stochastic quasi-linear heat equation. Finite-difference and symplectic partitioned Runge-Kutta (SPRK) schemes are used for space and time discretizations, respectively. It is the first time that a SPRK scheme is employed for the optimal control of stochastic partial differential equations. Monte-Carlo simulation is applied to handle expectation appearing in the cost functional. We present our results together with a numerical example. The paper ends with a conclusion and an outlook to future studies, on further research questions and applications.Article Citation - WoS: 18Citation - Scopus: 21Failure Rates of Consecutive k-out-of-n< Systems(Springer Heidelberg, 2012) Eryilmaz, Serkan; Navarro, JorgeLinear and circular consecutive k-out-of-n systems are very popular models in reliability theory, survival analysis, and biological disciplines and other related lifetime sciences. In these theories, the failure rate function is a key notion for measuring the ageing process. In this paper we obtain some mixture representations for consecutive systems and we apply a mixture-based failure rate analysis for both linear and circular consecutive systems. In particular, we analyze the limiting behavior of the system failure rate when the time increases and we obtain some ordering properties. We first consider the popular case of systems with components having independent and identically distributed lifetimes. In practice, these assumptions may fail. So we also study the case of independent non-identically distributed component lifetimes. This case has special interest when a cold-standby redundancy is used for some components. In this sense, we analyze where to place the best components in the systems. Even more, we also study systems with dependent components by assuming that their lifetimes are exchangeable. (C) 2011 The Korean Statistical Society. Published by Elsevier B.V. All rights reserved.Article Citation - WoS: 14Citation - Scopus: 15Yielding of Two-Layer Shrink-Fitted Composite Tubes Subject To Radial Pressure(Springer Heidelberg, 2005) Eraslan, AN; Akis, TYielding of two-layer shrink-fitted composite tubes with axially constrained ends subject to either internal or external pressure is investigated in detail. In the framework of small deformations, a state of plane strain and von Mises yield criterion, analytical expressions are obtained for critical values of the pressure leading to plastic flow. It is shown that, depending on material properties and tube dimensions, different modes of plastic deformation may occur. Yielding may commence at the inner tube or at the outer tube or simultaneously in both tubes. The conditions for different nature of plastic flow are determined. Using analytical expressions obtained for critical values of the parameters and properties of real engineering materials, various numerical examples are handled and the variation of elastic limit pressure with interference and interface radius is explained.
