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Article Citation - WoS: 14Citation - Scopus: 17NEW EDOT CONTAINING POLYMERS: EFFECT OF RING SIZE ON THE BENZIMIDAZOLE ACCEPTOR(Pergamon-elsevier Science Ltd, 2016) Cansu-Ergun, E. G.; Onal, A. M.; Cihaner, A.In this study, three different benzimidazole (BIm) based acceptor groups bearing cyclohexane, cycloheptane and cyclooctane rings at 2-C position of benzimidazole were synthesized and coupled with ethylenedioxythiophene (EDOT) donor units via Stille cross-coupling reaction. The resulting donor acceptor-donor (DAD) type monomers were examined in terms of their electrochemical and optical behaviors. All three monomers exhibited dual absorption bands due to their donor-acceptor pattern and exhibited one irreversible oxidation peak at about 0.80 V. The monomers were electrochemically polymerized via both potentiostatic and potentiodynamic methods and electro-optical properties of obtained conjugated polymer films were investigated in monomer free electrolytic solution. It was found that the polymer films exhibited quasi-reversible redox behavior due to the doping/dedoping process of the polymers, which was accompanied by a reversible electrochromic behavior. Electrochromic investigations showed that all three polymer films showed similar multichromic behaviors: green in the neutral state, gray in the oxidized state, and brick-red in the reduced state. Their band gap (Eg) values were elucidated utilizing spectroelectrochemical data and it was found to be around 1.18 eV. Furthermore, one of the polymer film was utilized for the construction of transmissive type electrochromic device (ECD) with poly(3,4-ethylenedioxythiophene) (PEDOT). (C) 2015 Elsevier Ltd. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5Performance Analysis of a Gas-To System Based on Protonic-Ceramic Electrochemical Compressor(Pergamon-elsevier Science Ltd, 2023) Baniasadi, Ehsan; Ghojavand, Fateme; Colpan, Can Ozgur; Devrim, YilserIn this study, two scenarios are considered to evaluate the performance of a protonic ceramic electrochemical hydrogen compressor (EHC) and reformer integrated with a pro-ton exchange membrane fuel cell (PEMFC). First scenario includes integration of an EHC with PEMFC and in the second scenario, steam methane reforming (SMR) is replaced by an EHC. Results show that the highest energy and exergy efficiencies of the system in the first scenario is achieved when the area-specific resistance (ASR) in EHC is 1.5 Ucm2. An in-crease in the working temperature of EHC causes a considerable rise in the exergy destruction and an increase of energy efficiency by 7% in the first scenario, while the temperature of the reformer affects the exergy destruction, negligibly. The parametric study indicates that the best value of the current density of PEMFC is 0.8481 A/cm2 and 0.8324 A/cm2 and the best current density of PEM-EHC value is 0.4468 A/cm2 and 0.11 A/cm2 in the 1st and 2nd scenarios, respectively. Under the same conditions, energy and exergy efficiencies for the first scenario are 61.63% and 54.9% and for the second scenario are 42.48% and 14.61%, respectively.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Letter Discussion of the Article "approximate Solution of Limit Angular Speed for Externally Loaded Rotating Solid Disk" by S. Bhowmick, D. Misra and Nk Saha [int J Mech Sci 2008;50:163-74](Pergamon-elsevier Science Ltd, 2008) Eraslan, Ahmet N.; Akis, Tolga[No Abstract Available]Article Citation - WoS: 10Citation - Scopus: 11Is There Convergence in Renewable Energy Deployment? Evidence From a New Panel Unit Root Test With Smooth and Sharp Structural Breaks(Pergamon-elsevier Science Ltd, 2023) Corakci, Aysegul; Omay, TolgaThis study examines whether the contribution of renewable energy to the total primary energy supply converges in a panel of 24 OECD countries over the period 1960-2020. To this end, a new panel unit root test that allows for both sharp and smooth breaks is proposed to test for the stochastic convergence hypothesis. Although renewable energy convergence is not rejected when the newly proposed test is applied to the full panel of OECD countries, it found only moderate support within the members of the panel using a sequential panel selection methodology. In fact, in two high-income OECD countries, the contribution of renewable energy to the primary energy supply shows no sign of convergence: Poland and Iceland. Therefore, the renewable energy shares seem to be converging to a common steady state in only a group of OECD countries over the long run. This uneven pattern of convergence, in turn, suggests that the OECD countries are still far away from developing a common sustainable renewable energy target, calling for urgent international policy cooperation to encourage the divergent econo-mies to seek out the menu of policies that ensure the worldwide success of renewable energy transformation.Article Citation - WoS: 21Citation - Scopus: 21Synthesis and Properties of a Novel Redox Driven Chemiluminescent Material Built on a Terthienyl System(Pergamon-elsevier Science Ltd, 2009) Atilgan, Nurdan; Algi, Fatih; Onal, Ahmet M.; Cihaner, AtillaA novel redox driven chemiluminescent material built on a terthienyl system, namely 5,7-di-ethylenedioxythiophen-2-yl-2,3-dihydro-thieno[3,4-d]pyridazine-1,4-dione (ETE-Lum), which is soluble in both organic media and basic aqueous solution was synthesized and characterized. Furthermore, its polymer, PETE-Lum, which is one of the most rare examples of chemiluminescent polymeric materials bearing a pyridazine unit, was obtained successfully by electrochemical means. Both of the materials give chemiluminescence either by treatment with oxidants (H2O2 and/or KMnO4) or by the application of a potential pulse. (C) 2009 Elsevier Ltd. All rights reserved.Article Citation - WoS: 45Citation - Scopus: 46Carbon Nanotube-Graphene Supported Bimetallic Electrocatalyst for Direct Borohydride Hydrogen Peroxide Fuel Cells(Pergamon-elsevier Science Ltd, 2021) Uzundurukan, Arife; Akca, Elif Seda; Budak, Yagmur; Devrim, YilserAt present study, carbon nanotube-graphene (CNT-G) supported PtAu, Au and Pt catalysts were prepared by microwave-assisted synthesis method to investigate the direct liquid-fed sodium borohydride/hydrogen peroxide (NaBH4/H2O2) fuel cell performance. Prepared catalysts were characterized by TGA, XRD, TEM, ICP-OES, cyclic voltammetry and rotating disc electrode (RDE) voltammetry. The catalysts were tested in a single NaBH4/H2O2 fuel cell with 25 cm(2) active area to evaluate fuel cell performance. The effects of temperature and fuel concentration on fuel cell performance were examined to observed best operating conditions. As a result of direct NaBH4/H2O2 fuel cell experiments, maximum power densities of 139 mW/cm(2), 125 mW/cm(2) and 113 mW/cm(2) were obtained for PtAu/CNT-G, Au/CNT-G and Pt/CNT-G catalysts, respectively. PtAu/CNT-G catalyst showed the enhanced NaBH4/H2O2 fuel cell performance, which was higher than the Pt/CNT-G catalyst and Au/CNT-G catalyst at 50 degrees C. The enhanced NaBH4/H2O2 performance can be attributed to synergistic effects between Pt and Au particles on CNT-G support providing a better catalyst utilization and interaction. These results suggest that the prepared PtAu/CNT-G catalyst is a promising anode catalyst for NaBH4/H2O2 fuel cell application. (c) 2020 Elsevier Ltd. All rights reserved.Article Citation - WoS: 15Citation - Scopus: 17Performance Evaluation of Laser Induced Breakdown Spectroscopy in the Measurement of Liquid and Solid Samples(Pergamon-elsevier Science Ltd, 2018) Bilge, Gonca; Sezer, Banu; Boyaci, Ismail Hakki; Eseller, Kemal Efe; Berberoglu, HalilLiquid analysis by using LIBS is a complicated process due to difficulties encountered during the collection of light and formation of plasma in liquid. To avoid these, some applications are performed such as aerosol formation and transforming liquid into solid state. However, performance of LIBS in liquid samples still remains a challenging issue. In this study, performance evaluation of LIBS and parameter optimizations in liquid and solid phase samples were performed. For this purpose,milk was chosen as model sample; milk powder was used as solid sample, and milk was used as liquid sample in the experiments. Different experimental setups have been constructed for each sampling technique, and optimizations were performed to determine suitable parameters such as delay time, laser energy, repetition rate and speed of rotary table for solid sampling technique,and flow rate of carrier gas for liquid sampling technique. Target element was determined as Ca, which is a critically important element in milk for determining its nutritional value and Ca addition. In optimum parameters, limit of detection (LOD), limit of quantification (LOQ) and relative standard deviation (RSD) values were calculated as 0.11%, 0.36% and 8.29% respectively for milk powders samples; while LOD, LOQ and RSD values were calculated as 0.24%, 0.81%, and 10.93% respectively for milk samples. It can be said that LIBS is an applicable method in both liquid and solid samples with suitable systems and parameters. However, liquid analysis requires much more developed systems for more accurate results. (C) 2018 Elsevier B.V.All rights reserved.Letter Amendments on "application of Mises Yield Criterion To Rotating Solid Disk Problem" by N. Aleksandrova [int. J. Eng. Sci. 51 (2012) 333-337](Pergamon-elsevier Science Ltd, 2012) Eraslan, Ahmet N.; Akis, Tolga[No Abstract Available]Article Citation - WoS: 36Citation - Scopus: 42Development of a Personalized Thermal Comfort Driven Controller for Hvac Systems(Pergamon-elsevier Science Ltd, 2021) Turhan, Cihan; Simani, Silvio; Akkurt, Gulden GokcenIncreasing thermal comfort and reducing energy consumption are two main objectives of advanced HVAC control systems. In this study, a thermal comfort driven control (PTC-DC) algorithm was developed to improve HVAC control systems with no need of retrofitting HVAC system components. A case building located in Izmir Institute of Technology Campus-Izmir-Turkey was selected to test the developed system. First, wireless sensors were installed to the building and a mobile application was developed to monitor/ collect temperature, relative humidity and thermal comfort data of an occupant. Then, the PTC-DC algorithm was developed to meet the highest occupant thermal comfort as well as saving energy. The prototypes of the controller were tested on the case building from July 3rd, 2017 to November 1st, 2018 and compared with a conventional PID controller. The results showed that the developed control algorithm and conventional controller satisfy neutral thermal comfort for 92 % and 6 % of total measurement days, respectively. From energy consumption point of view, the PTC-DC decreased energy consumption by 13.2 % compared to the conventional controller. Consequently, the PTC-DC differs from other works in the literature that the prototype of PTC-DC can be easily deployed in real environments. Moreover, the PTC-DC is low-cost and user-friendly. (c) 2021 Elsevier Ltd. All rights reserved.Review Citation - WoS: 39Citation - Scopus: 43Hydropower in Turkey: Analysis in the View of Vision 2023(Pergamon-elsevier Science Ltd, 2013) Melikoglu, MehmetTurkey is a recently developed country, a regional power in the Middle East and an economic powerhouse of the region. Turkey's electricity demand is continuously increasing due to fast economic growth coupled with the country's vibrant young population. It is envisaged that this demand would keep on increasing almost exponentially in the next decade according to the recently avowed Vision 2023 agenda. According to which, the Turkish government ambitiously wants to provide 30.0% of the country's electricity demand from renewable energy sources by 2023. Turkey has vast renewable energy potential including hydro, geothermal, solar and wind. However, historically there is only one playmaker that is hydropower. Thus a detailed review of the current status and future prospects of Turkish hydropower market is urgently needed to generate a roadmap for the Vision 2023 agenda. This paper was intended to provide that vital information. Currently, more than 25.0% or 57.5 TWh of the country's electricity demand is supplied from hydropower. According to official projections this would increase to approximately 116.0 TWh in 2023. In this study, hydropower's supply rate of Turkey's annual electricity demand was assessed based on the official projections and a forecast was generated. Results showed that between 22.0% and 27.0% of Turkey's annual electricity demand should be supplied from hydropower in 2023. Therefore, between 22.5 TWh and 45.0 TWh of electricity should be generated from renewable energy sources other than hydropower to provide a total of 30.0% renewable energy based electricity generation in 2023. (C) 2013 Elsevier Ltd. All rights reserved.
