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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 Gokcen; Gokcen Akkurt, GuldenIncreasing 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.Article Citation - WoS: 14Citation - Scopus: 15Lmi Approach To the Global Robust Stability of a Larger Class of Neural Networks With Delay(Pergamon-elsevier Science Ltd, 2007) Singh, VimalSufficient conditions in the form of linear matrix inequality for the uniqueness and global asymptotic stability of the equilibrium point of a large class of uncertain neural networks with delay are presented. The conditions are based on norm-bounded uncertainties. An example is given to show the effectiveness of the obtained results. A comparison is made between the present approach and an earlier approach due to Lu, Rong and Chen. An error is corrected in an earlier publication. (c) 2006 Elsevier Ltd. All rights reserved.Article Citation - WoS: 59Citation - Scopus: 68Generalized (c)-conditions and Related Fixed Point Theorems(Pergamon-elsevier Science Ltd, 2011) Karapinar, Erdal; Tas, Kenan; Karapnar, ErdalIn this manuscript, the notion of C-condition [K. Suzuki, Fixed point theorems and convergence theorems for some generalized nonexpansive mappings, J. Math. Anal. Appl. 340 (2008) 1088-1095] is generalized. Some new fixed point theorems are obtained. (C) 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 83Citation - Scopus: 92Investigation of Micro-Combined Heat and Power Application of Pem Fuel Cell Systems(Pergamon-elsevier Science Ltd, 2018) Budak, Yagmur; Devrim, YilserThis study focuses on the investigating different working temperature effect on Proton Exchange Membrane Fuel Cell (PEMFC) stack performance, micro-combined heat and power (mu CHP) application and their simple payback time. LT-PEMFC and HT-PEMFC short stacks were designed and analyzed for 480 W net power output. Liquid cooling method was choosing for the cooling the PEMFC stacks due for efficient mu CHP applications. The experimental studies were carried out by using 13 cells HT-PEMFC and 6 cells LT-PEMFC short stacks and design parameters were determined. 1.2 kW PEMFCs with mu CHP systems with different working temperature were designed based on electrochemical data obtained from short stack testing. The proposed PEMFC systems can supply electric and hot water. The highest mu CHP system efficiency was calculated with a value of 92% for HT-PEMFC based system. The corresponding electrical and thermal efficiencies are 48% and 44%, respectively. In this study, two important parameters have been analyzing: efficiency and simple payback time. By using mu CHP application, both natural gas and H-2 based PEMFC systems SPT values are reduced.Article Citation - WoS: 2Citation - Scopus: 2Structural, Electrical and Anisotropic Properties of Tl4se3< Chain Crystals(Pergamon-elsevier Science Ltd, 2009) Qasrawi, A. F.; Gasanly, N. M.The structure, the anisotropy effect on the current transport mechanism and the space charge limited current in Tl4Se3S chain crystals have been studied by means of X-ray diffraction, electrical conductivity measurements along and perpendicular to the crystal's c-axis and the current voltage characteristics. The temperature-dependent electrical conductivity analysis in the region of 150-400 K, revealed the domination of the thermionic emission of charge carriers over the chain boundaries above 210 and 270 K along and perpendicular to the c-axis, respectively. Below these temperatures, the variable range hopping is dominant. At a consistent temperature range, the thermionic emission analysis results in conductivity activation energies of 280 and 182 meV, along and perpendicular to the c-axis, respectively. Likewise, the hopping parameters are altered significantly by the conductivity anisotropy. The current-voltage characteristics revealed the existence of hole trapping state being located at 350 meV above the valence band of the crystal. (C) 2009 Elsevier Ltd. All rights reserved.Article Citation - WoS: 13Citation - Scopus: 13Numerical Solution of Buoyancy Mhd Flow With Magnetic Potential(Pergamon-elsevier Science Ltd, 2014) Pekmen, B.; Tezer-Sezgin, M.In this study, dual reciprocity boundary element method (DRBEM) is applied for solving the unsteady flow of a viscous, incompressible, electrically conducting fluid in channels under the effect of an externally applied magnetic field and buoyancy force. Magnetohydrodynamics (MHD) equations are coupled with the energy equation due to the heat transfer by means of the Boussinessq approximation. Then, the 20 non-dimensional full MHD equations in terms of stream function, temperature, magnetic potential, current density and vorticity are solved by using DRBEM with implicit backward Euler time integration scheme. Numerical results are obtained utilizing linear boundary elements and linear radial basis functions approximation for the inhomogeneities, in a double lid-driven staggered cavity and in a channel with backward facing step. The results are given for several values of problem parameters as Reynolds number (Re), magnetic Reynolds number (Rem), Hartmann number (Ha) and Rayleigh number (Ra). With the increase in Rem, both magnetic potential and current density circulate near the abrupt changes of the walls. The increase in Ha suppresses this perturbation, and forces the magnetic potential lines to be in the direction of the applied magnetic field. The boundary layer formation through the walls emerge in the flow and current density for larger values of Ha. (C) 2013 Elsevier Ltd. All rights reserved.Article Citation - WoS: 11Citation - Scopus: 15Energy Multiplication and Fissile Fuel Breeding Limits of Accelerator-Driven Systems With Uranium and Thorium Targets(Pergamon-elsevier Science Ltd, 2015) Sahin, Sumer; Sarer, Basar; Celik, YurdunazThe study analyses the integral U-233 and Pu-239 breeding rates, neutron multiplication ratio through (n,xn)- and fission-reactions, heat release, energy multiplication and consequently the energy gain factor in infinite size thorium and uranium as breeder material in an accelerator driven systems (ADS), irradiated by a 1-GeV proton source. Energy gain factor has been calculated as M-energy = 1.67, 4.03 and 5.45 for thorium, depleted uranium (100% U-238) and natural uranium, respectively, where the infinite criticality values are k(infinity) = 0.40, 0.752 and 0.816. Fissile fuel material production is calculated as 53 Th-232(n,gamma)U-233, 80.24 and 90.65 U-238(n,gamma)Pu-239 atoms per incident proton, respectively. The neutron spectrum maximum is by similar to 1 MeV. Lower energy neutrons E < 1 MeV have major contribution on fissile fuel material breeding (>97.5%), whereas their share on energy multiplication is negligible (0.2%) for thorium, depleted uranium. Major fission events occur in the energy interval 1MeV < E < 50 MeV. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 11Citation - Scopus: 12Some Fixed Point Results on Interpolative Metric Spaces(Pergamon-elsevier Science Ltd, 2025) Karapinar, Erdal; Agarwal, Ravi P.This paper aims to introduce some basic fixed point theorems on interpolative metric space that is a natural extension of standard metric space.Review Citation - WoS: 88Citation - Scopus: 95Vision 2023: Forecasting Turkey's Natural Gas Demand Between 2013 and 2030(Pergamon-elsevier Science Ltd, 2013) Melikoglu, MehmetNatural gas is the primary source for electricity production in Turkey. However, Turkey does not have indigenous resources and imports more than 98.0% of the natural gas it consumes. In 2011, more than 20.0% of Turkey's annual trade deficit was due to imported natural gas, estimated at US$ 20.0 billion. Turkish government has very ambitious targets for the country's energy sector in the next decade according to the Vision 2023 agenda. Previously, we have estimated that Turkey's annual electricity demand would be 530,000 GWh at the year 2023. Considering current energy market dynamics it is almost evident that a substantial amount of this demand would be supplied from natural gas. However, meticulous analysis of the Vision 2023 goals clearly showed that the information about the natural gas sector is scarce. Most importantly there is no demand forecast for natural gas in the Vision 2023 agenda. Therefore, in this study the aim was to generate accurate forecasts for Turkey's natural gas demand between 2013 and 2030. For this purpose, two semi-empirical models based on econometrics, gross domestic product (GDP) at purchasing power parity (PPP) per capita, and demographics, population change, were developed. The logistic equation, which can be used for long term natural gas demand forecasting, and the linear equation, which can be used for medium term demand forecasting, fitted to the timeline series almost seamlessly. In addition, these two models provided reasonable fits according to the mean absolute percentage error, MAPE %, criteria. Turkey's natural gas demand at the year 2030 was calculated as 76.8 billion m(3) using the linear model and 83.8 billion m(3) based on the logistic model. Consequently, found to be in better agreement with the official Turkish petroleum pipeline corporation (BOTAS) forecast, 76.4 billion m(3), than results published in the literature. (C) 2013 Elsevier Ltd. All rights reserved.
