Browsing by Author "Aktas, Z."

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Open Access
Coordination between monetary policy and fiscal policy for an inflation targeting emerging market
(Pergamon Press, 2010) Aktas, Z.; Kaya, N.; Özlale, Ü.
Several studies including Blanchard (2004) and Favero and Giavazzi (2004) imply that in emerging market economies, a tight monetary policy within an inflation-targeting framework could actually increase the price level due to the lack of fiscal discipline and the associated high risk premium. We extend their arguments in two ways. First, we introduce a semi structural model with time-varying parameters, where the risk premium is 'unobserved' and it is derived within the system. Such an approach fits better with the volatile nature of emerging market economies by allowing us to track down the time-varying effects of macroeconomic dynamics on both the model-consistent risk premium and the other key variables. Second, we obtain impulse response functions and analyze the implications of a tight monetary policy on major macroeconomic variables. Taking the Turkish economy as our reference point, we find that the arguments of Blanchard (2004) and Favero and Giavazzi (2004) seem to be valid. © 2009 Elsevier Ltd. All rights reserved.
Open Access
Examination of gas and solid products during the preparation of activated carbon using phosphoric acid
(Academic Press, 2018) Yagmur, E.; Inal, I. I. G.; Gokce, Y.; Ghobadi, T. G. U.; Aktar, T.; Aktas, Z.
Activating agents play significant roles in the preparation of activated carbon (AC) from biomasses and their wastes, which are widely used in AC production. Application methods are also important for the production process. Products give remarkable ideas regarding the method and heat treatment process. The activated carbon was produced from waste tea in accordance with either the conventional method or microwave energy pretreated method using phosphoric acid (H3PO4) as activating agent. The yields of the activated carbons were 51.8% for conventional method and 46.0% for microwave pretreated method. The acid suppressed the formation of tar and promoted the amount of solid and aromatic structure accordance to sp2 hybridisation. Additionally, the waste tea was directly carbonised (without H3PO4) and the yield was 36.3%. Major gas (H2, CH4, C2H6, C2H4, CO2 and CO) products obtained during heat treatment process in a conventional furnace were examined in terms of quantity and quality. The solid products were characterised in terms of surface area, pore size and surface properties. The result of gas analysis showed that phosphoric acid affected formation of activated carbon mechanism and significant reactions occurred during microwave pretreatment process.
Open Access
Highly stable Megalopolis lignite based N and S self-doped hierarchically porous activated carbons for high performance supercapacitors and ash content effects on performance
(Elsevier, 2022-02) Oglou, Ramadan Chalil; Gokce, Y.; Yagmur, E.; Ghobadi, T.Gamze Ulusoy; Aktas, Z.
This study proposes that high value-added activated carbon (AC) is produced from lignite (low rank coal) and used as electrode material in supercapacitors. In addition, the effects of the ash content of the activated carbon on supercapacitor performance are determined. The ACs at a temperature of 800 °C are produced in three different impregnation ratios (IR) (IR: 1, 2 and 4: KOH/precursor) using KOH as the activation agent. While the surface area of the AC produced at IR4 is 2531.4 m2 g−1, it is determined as 1321.3 (IR1) and 1989.0 (IR2) m2 g−1 for the others. The pore size analysis of the samples shows that the mesopores are dominant in the IR1 (52.73%) and IR4 (88.74%) samples, while it is observed that the micropores are dominant in the IR2 (69.03%) sample. The IR4 sample gives excellent results. The cell specific capacitances of this sample are determined as 260.47 F g−1 (at 1 A g−1) and 150.3 F g−1 (at 50 A g−1). The amount of ash in the AC samples dramatically reduces the supercapacitor performances and significantly increases the resistances.