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Now showing 1 - 10 of 36
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    Citation - WoS: 1
    Citation - Scopus: 1
    The Number of Irreducible Polynomials Over Finite Fields With Vanishing Trace and Reciprocal Trace
    (Springer, 2022) Cakiroglu, Yagmur; Yayla, Oguz; Yilmaz, Emrah Sercan
    We present the formula for the number of monic irreducible polynomials of degree n over the finite field F-q where the coefficients of x(n)(-1) and x vanish for n >= 3. In particular, we give a relation between rational points of algebraic curves over finite fields and the number of elements a is an element of F-qn for which Trace(a) = 0 and Trace(a(-1)) = 0.
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    Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Thermoluminescence Properties of Zno Nanoparticles in the Temperature Range 10-300 K
    (Springer, 2016) Isik, M.; Yildirim, T.; Gasanly, N. M.
    Low-temperature thermoluminescence (TL) properties of ZnO nanoparticles grown by sol-gel method were investigated in the 10-300 K temperature range. TL glow curve obtained at 0.2 K/s constant heating rate exhibited one broad peak around 83 K. The observed peak was analyzed using curve fitting method to determine the activation energies of trapping center(s) responsible for glow curve. Analyses resulted in the presence of three peaks at 55, 85 and 118 K temperatures with activation energies of 12, 30 and 45 meV, respectively. Thermal cleaning process was applied to separate overlapped peaks and get an opportunity to increase the reliability of results obtained from curve fitting method. Heating rate dependence of glow curve was also studied for rates between 0.2 and 0.7 K/s. The shift of the peak maximum temperatures to higher values and decrease in peak height with heating rate were observed. Moreover, X-ray diffraction and scanning electron microscopy were used for structural characterization.
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    Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Birman-Hilden Property of Covering Spaces for Nonorientable Surfaces
    (Springer, 2020) Atalan, F.; Medetogullari, E.
    Let p : (N) over tilde -> N be a finite covering space for nonorientable surfaces, where chi((N) over tilde) < 0. We study whether or not p has the Birman-Hilden property.
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    Citation - WoS: 1
    Citation - Scopus: 1
    An Empirical Analysis of the Average Plant Start-Up Size in Turkish Manufacturing Industries
    (Springer, 2012) Cilasun, Seyit Mumin; Gunalp, Burak
    Many studies have found start-up size of a firm to be an important determinant of its subsequent performance and probability of survival. The aim of this study is to investigate the determinants of average plant start-up size in 51 four-digit Turkish manufacturing industries for the period 1993-1999. The results of the study suggest that while industry characteristics such as industry growth rate and capital intensity have a positive impact on the average plant start-up size, industrial concentration, import penetration, and the change in research and development expenditures are negatively associated with the same variable. In addition, the macroeconomic environment is also an important determinant of the choice of plant start-up size. Finally, we find evidence that may indicate 'following' (herd) behavior in Turkish manufacturing industries.
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    Citation - WoS: 6
    Citation - Scopus: 5
    Finite Number of Fibre Products of Kummer Covers and Curves With Many Points Over Finite Fields
    (Springer, 2014) Ozbudak, Ferruh; Temur, Burcu Gulmez
    We study fibre products of a finite number of Kummer covers of the projective line over finite fields. We determine the number of rational points of the fibre product over a rational point of the projective line, which improves the results of Ozbudak and Temur (Appl Algebra Eng Commun Comput 18:433-443, 2007) substantially. We also construct explicit examples of fibre products of Kummer covers with many rational points, including a record and two new entries for the current table (http://www.manypoints.org, 2011).
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    Article
    Citation - WoS: 10
    Citation - Scopus: 9
    A Computational Study on 4,7-Di(furan Monomer and Its Oligomers
    (Springer, 2014) Kayi, Hakan; Kayı, Hakan; Kayı, Hakan; Chemical Engineering; Chemical Engineering
    The energy gap, Eg, between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels that determines the electronic and optical properties of 4,7-di(furan-2yl)benzo[c][1,2,5]thiadiazole (FSF) polymer is calculated by performing quantum chemical calculations. First, we theoretically investigated the most stable conformers of FSF monomer and its corresponding oligomers at the B3LYP/6-31G(d) and B3LYP/LANL2DZ levels of theory. We reveal the theoretical molecular structure of this very recently synthesized novel monomer and its oligomers for the first time in the literature. Our results from the B3LYP/6-31G(d) calculations indicated that FSF polymer has a low HOMO-LUMO gap of 1.55 eV to be in good agreement with the experiments. Experimental design and synthesis of novel conjugated polymers require time-consuming and expensive procedures. The findings from this study are promising for the use of computational methods in the design of the novel conjugated polymers, and help to narrow the materials to be used in design and synthesis of conjugated polymers with desired properties.
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    Common Fixed Point Results for Meir-Keeler-Type Contraction Mappings
    (Springer, 2025) Karapńar, Erdal; Cvetković, Marija, S.; Yeşilkaya, Seher Sultan
    Meir–Keeler contraction presents an interesting and widely studied topic in the area of Metric Fixed Point Theory. We intend to present several results concerning common fixed problem and the impact of Meir-Keeler-type contractions on this type of results. We will present results on common fixed problem for a Meir–Keeler contraction mapping in various settings—metric space, b-metric space, partial metric space, Branciari metric space, etc. It is our intention to present a comprehensive study on this topic that will present a good starting point for the researchers in the Fixed Point Theory. © 2025 Elsevier B.V., All rights reserved.
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    Citation - WoS: 25
    Citation - Scopus: 28
    Palladium(0) Nanoparticles Supported on Hydroxyapatite Nanospheres: Active, Long-Lived, and Reusable Nanocatalyst for Hydrogen Generation From the Dehydrogenation of Aqueous Ammonia-Borane Solution
    (Springer, 2014) Karatas, Yasar; Yurderi, Mehmet; Gulcan, Mehmet; Zahmakiran, Mehmet; Kaya, Murat
    Among the solidmaterials considered in the chemical hydrogen storage, ammonia-borane (NH3-BH3) appears to be one of the promising candidates as it can release hydrogen throughout hydrolysis in the presence of suitable catalyst under mild conditions. Herein we report, for the first time, the preparation and characterization of palladium(0) nanoparticles supported on nanohydroxyapatite and their catalytic use in the hydrolysis of ammonia-borane under air at room temperature. These new palladium(0) nanoparticles were generated in situ during the catalytic hydrolysis of ammonia-borane starting with palladium(II) immobilized nanohydroxyapatite. The preliminary characterization of the palladium(0) nanoparticles supported on nanohydroxyapatite was done by the combination of complimentary techniques, which reveals that the formation of well-dispersed Pd(0)NPs nanoparticles (1.41 +/- 0.52 nm) on the surface of hydroxyapatite nanospheres (60-150 nm). The resulting palladium nanocatalyst achieves hydrogen generation from the hydrolysis of ammonia-borane with an initial turnover frequency value (TOF) of 11 mol H-2 mol(-1) Pd x min at room temperature under air. In addition to their high activity, the catalytic lifetime experiment showed that they can also act as a long-lived heterogeneous catalyst for this reaction (TTON = 14,200 mol H-2 mol(-1) Pd) at room temperature under air. More importantly, nanohydroxyapatite- supported palladium(0) nanoparticles were found to be highly stable against to leaching and sintering throughout the catalytic runs that make them isolable, bottleable, and reusable heterogeneous catalyst for the hydrolysis of ammonia-borane.
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    Time Complexity Comparison of Stopping at First Failure and Completely Running the Test
    (Springer, 2020) Yucesan, Ongun; Ozkil, Altan
    For a given test set, we compare two test application techniques, "stopping at first failure" and "complete run", respectively. The former stops the test whenever a failure is encountered. The latter however, carries on till the end. Our comparison concludes that although the first technique is generally faster, there is no strong evidence to support a complete rejection of the second technique for it provides statistics useful in test planning. Results support an interchangeable application of both techniques with more frequent use of stopping at first failure. Even though there are numerous studies to decide how to prioritize and select test cases (TC), or to examine dependencies of TCs and codes, the presented comparison of the two test application techniques for a given "test set" has the potential to reduce the total run time of the test.