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Öğe APPLICATION OF NONLINEAR MODEL PREDICTIVE CONTROL BASED ON DIFFERENT MODELS TO BATCH POLYMERIZATION REACTOR(DIPTEM UNIV GENOA, 2011) Cetinkaya, Sevil; Anakh, Duygu; Zeybek, Zehra; Hapoglu, Hale; Alpbaz, Mustafa; Bruzzone, A; DauphinTanguy, G; Junco, S; Piera, MAIn the present work, at the previously determined optimal conditions, to control batch polymerization reactor, Linear Generalized Predictive Control (LGPC) and Nonlinear Generalized Predictive Control (NLGPC) algorithm were utilized. Several system models were applied to the control algorithms. The effect of different optimal. conditions has been examined on monomer conversion, average viscosity molecular weight and chain length. At the same operating conditions of LGPC and NLGPC temperature control was used for comparison: According to the experimental results, the performance of NLGPC was obtained well than LGPC control method. In addition, the results denoted that the NLGPC control performances depend on different models and the optimum conditions.Öğe Application of nonlinear model predictive control based on different models to batch polymerization reactor(I3M Conference, 2011) Cetinkaya, Sevil; Anakli, Duygu; Zeybek, Zehra; Hapoglu, Hale; Alpbaz, MustafaIn the present work, at the previously determined optimal conditions, to control batch polymerization reactor, Linear Generalized Predictive Control (LGPC) and Nonlinear Generalized Predictive Control (NLGPC) algorithm were utilized. Several system models were applied to the control algorithms. The effect of different optimal conditions has been examined on monomer conversion, average viscosity molecular weight and chain length. At the same operating conditions of LGPC and NLGPC temperature control was used for comparison. According to the experimental results, the performance of NLGPC was obtained well than LGPC control method. In addition, the results denoted that the NLGPC control performances depend on different models and the optimum conditions.Öğe APPLICATION OF TEMPERATURE CONTROL IN A BATCH POLYMERIZATION REACTOR AT DIFFERENT OPTIMAL TEMPERATURES(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2013) Cetinkaya, Sevil; Durmazucar, Hasan H.; Zeybek, Zehra; Hapoglu, Hale; Alpbaz, MustafaThe generalized delta rule (GDR) algorithm with generalized predictive control (GPC) was used to control the temperature of a jacketed batch reactor in which styrene polymerization occurs under isothermal conditions. The effects of different optimal conditions were examined on monomer conversion, average viscosity molecular weight and chain length. The neural network model based on the relation between the reactor temperature and heat input to the reactor was used. The efficiency of the GDR with GPC was examined by simulation and experimentally using GDR parameters specified at constant temperatures, and compared with Self-Tuning PID (STPID). It was observed that the control experiments provided a good performance in maintaining the reactor temperature at its set point and yielded polymer product with desired properties.Öğe Conductive potassium feldspar/polyaniline composites prepared by in situ chemical polymerization(ELSEVIER SCIENCE SA, 2007) Cetinkaya, Sevil; Karakisla, Meral; Oezer, Ali; Sacak, MehmetK-feldspar particles using potassium dichromate in an acidic aqueous medium. The effects of K-feldspar particle size, aniline concentration and temperature upon the PAn amount in the composite and the electrical surface resistance of the composites were examined. Electrical conductivity was higher in the composites prepared by the smaller K-feldspar particles in which the PAn yield is low. The microhardness values of K-feldspar/PAn composites increased to a certain PAn content and then decreased. The microhardness of the composites containing PAn in the range of 1-6%, which were prepared by K-feldspar having particle size smaller than 0.125-0.250 nm, was higher that of pure K-feldspar and PAn (0.843 kPa). Scanning electron microscopy (SEM) showed that PAn covered the surface of K-feldspar particles with an unsmooth PAn layer. The characterization of composites was also made by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). (C) 2007 Elsevier B.V. All rights reserved.Öğe Electrochemical study of pyrite-ovalbumin interaction in relation to flotation(ELSEVIER SCIENCE BV, 2013) Guler, Taki; Sahbudak, Kemal; Cetinkaya, Sevil; Akdemir, UnalOvalbumin (OVA), chicken egg albumin, is an environmentally friendly, non-toxic, cheap surface active agent. It has electrochemically active sulfhydryl residues in molecular structure. OVA adsorption on pyrite as an alternative depressant was investigated by cyclic voltammetry, FTIR spectroscopy and flotation. Tests were conducted in a wide potential range in alkaline pH to clarify the role of electrochemical condition on the adsorption mechanisms and the rate of depression. In the absence of OVA, the floatability reached its maxima around slightly oxidizing condition. Beyond the range, it decreased presumably due to the formation of Fe-oxyhydroxides together with the hydrophilic S-containing species. OVA-pyrite interaction occurred in the whole examined potential range. Depressing effect of OVA increased gradually from reducing to slightly oxidizing potential, open circuit potential (OCP) of pyrite, mainly due to weak conformational changes in OVA molecules together with the hydrophobic interaction around OCP. The rate of depression reached its maxima at moderately oxidizing potentials, which was referred to electrostatic attraction. This level was almost kept at higher potentials owing to OVA adsorption as metal-chelates.Öğe Green synthesis of copper oxide nanoparticles using black, green and tarragon tea and investigation of their photocatalytic activity for methylene blue(Pamukkale Univ, 2022) Kutuk, Nursah; Cetinkaya, SevilIn this study, copper oxide nanoparticles (CuO-NPs) were obtained by biosynthesis using aqueous extracts of black tea (BT), green tea (GT) and tarragon tea (TT). The effect of extracts from leaves of plants on the reduction mechanism has been investigated. The amount of polyphenol as using reducing agent in the extracts from the plants was determined according to the Folin-Ciocalteu's method. Total phenolic acid amounts of the extracts of BT, GT and TT were found as 59.18, 42.81 and 49.83 mg/L, respectively. Properties of synthesized CuO-NPs using these extracts were examined by UV-visible spectroscopy, Fourier infrared transformation spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and Atomic Force Microscopy (AFM) analysis. In addition, prepared CuO-NPs were used in methylene blue (MB) removal as a photocatalyst. According to AFM results, average size of CuO-NPs was determined ranging from 10 to 12 nm. Regarding photocatalytic activity, prepared CuO-NPs from BT, GT and TT removed 89%, 87% and 90% of dye in 360 min, respectively. In the photocatalytic removal study, the reaction kinetics were investigated with zero, first and second order kinetics.Öğe Green Synthesis of Iron Oxide Nanoparticles Using Black Tea Extract and Investigation of Its Properties(AMER SCIENTIFIC PUBLISHERS, 2018) Cetinkaya, Sevil; Kutuk, NursahIron oxide nanoparticles (FeNPs) were synthesized by green method using black tea (BT) extract as a reducing agent at room temperature. The effect of polyphenol content on the formation of FeNPs was investigated. The morphology of FeNPs could be controlled by changing the amount of BT extract and iron ions. The results showed that size and shape of the nanoparticles depended on the amount of polyphenol content of the mixture. Synthesized iron oxide nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy.Öğe IMPACT OF OVALBUMIN ON PYRITE FLOTATION IN THE ABSENCE AND PRESENCE OF METAL IONS(OFICYNA WYDAWNICZA POLITECHNIKI WROCLAWSKIEJ, 2014) Guler, Taki; Sahbudak, Kemal; Akdemir, Unal; Cetinkaya, SevilRecovery of gangue pyrite and its accidental activation are vital issues in flotation of complex sulfide ores. This work was performed by cyclic voltammetry (CV) and flotation tests to elucidate applicability of ovalbumin (OVA) as depressant for pyrite. The synergetic effect of metal ions in addition to its possible use in case of accidental activation by metal ions. CV tests stated that OVA adsorbed irreversibly on pyrite, and restricted electron transfer up to moderately oxidizing potentials due to electrostatic interaction together with weak hydrophobic interactions. At highly oxidizing potentials, adsorption occurred through electrochemical mechanisms through formation of metal-OVA chelates. Rate of pyrite depression with OVA was found to be potential dependent reaching its peak point around moderately oxidizing potentials both in absence and presence of metal ions. Electrochemically active metals display synergetic effect with OVA on pyrite depression, whereas noble metals activate pyrite and reduced depressing potency of OVA.Öğe Optimal temperature control in a batch polymerization reactor using fuzzy-relational models-dynamics matrix control(PERGAMON-ELSEVIER SCIENCE LTD, 2006) Cetinkaya, Sevil; Zeybek, Zehra; Hapoglu, Hale; Alpbaz, MustafaIn this work, fuzzy-relational models-dynamics matrix control (Fuzzy-DMC) was applied to the free radical solution polymerization of styrene in a jacketted batch reactor and its performance was examined to reach the required monomer conversion, molecular weight and chain length in a minimum time. The reactor temperature was controlled by manipulating the heat-input to the reactor. The performance of the Fuzzy-DMC controller was compared with that of the nonlinear generalized predictive control (NLGPC). (c) 2006 Elsevier Ltd. All rights reserved.Öğe Preparation of poly(2-ethyl aniline)/kaolinite composite materials and investigation of their properties(ELSEVIER SCIENCE BV, 2010) Anakli, Duygu; Cetinkaya, SevilConductive poly(2-ethyl aniline) (PEAn)/kaolinite composite was prepared by chemical polymerization in aqueous HCl medium in the presence of kaolinite particles by using potassium chromate (K2CrO4) as oxidant. Effects of polymerization conditions, such as concentrations of oxidant and 2-ethyl aniline, polymerization time and temperature on PEAn content and conductivity of composite, were investigated. The prepared composite material, having the highest PEAn content and conductivity, was obtained in the polymerization carried out at 20 degrees C for 2 h with 0.2 M K2CrO4 and 0.2 M EAn. It was observed that the micro-hardness of prepared composites increased with the increase in the PEAn contents of composites. The highest micro-hardness value of 7.92 kg mm(-2) was reached at 24.6% PEAn content. Characterization of composites was carried out by FTIR spectroscopy, XRD, TGA and SEM techniques. (C) 2009 Elsevier B.V. All rights reserved.Öğe Serum selenium and plasma malondialdehyde levels and antioxidant enzyme activities in patients with obsessive-compulsive disorder(PERGAMON-ELSEVIER SCIENCE LTD, 2009) Ozdemir, Ercan; Cetinkaya, Sevil; Ersan, Serpil; Kucukosman, Seda; Ersan, E. ErdalThere is mounting evidence indicating that reactive free radical species are involved in initiation and development of many different forms of human pathologies including psychiatric disorders. In the present study, we aimed to determine whether serum selenium (Se), antioxidant enzyme (glutathione peroxidase, GSH-Px, superoxide dismutase, SOD, and catalase, CAT) activities, and plasma malondialdehyde (MDA) levels, a product of lipid peroxidation, were associated with obsessive-compulsive disorder (OCD). The participants were 28 patients with OCD that were drug-free at least for a month and a control group (n = 28) of healthy subjects, matched with respect to age and sex. In both groups, the levels of the erythrocyte MDA, GSH-Px. SOD, Se, and the CAT were measured. The levels of MDA and SOD were statistically significantly higher (p<0.01, p<0.05 respectively) in patients than controls. The activities of CAT, GSH-Px, and serum Se levels were statistically significantly lower (p<0.0001, p<0.001, and p<0.001 respectively) in patients than controls. There was a positive correlation in patients between plasma GSH-Px activity and Se concentration (r=52, p=0.001). However, in patients with OCD, CAT and SOD activities were significantly and negatively correlated with MDA levels (r=-0.45, p=0.017 for CAT and r=-0.54, p=0.020 for SOD). The study shows the presence of a significant relationship of OCD and oxidative stress, and consequently, an involvement of free radicals and of the antioxidant defence. (c) 2008 Elsevier All rights reserved.Öğe Synthesis and characterization of conductive poly(o-anisidine)/talc composite(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2018) Anakli, Duygu; Cetinkaya, Sevil; Karakisla, Meral; Sacak, EhmetConductive poly(o-anisidine) (POA)/talc composite was prepared by chemical polymerization of o-anisidine in the presence of talc using ammonium persulfate (APS) as oxidant. The polymerization parameters such as APS/o-anisidine mol ratio, o-anisidine and HCl concentration on the conductivity and POA amount of the POA/talc composite were investigated. The increased microhardness property of the talc particles by the addition of the conducting polymer was examined by micro indentation analysis. The structural, morphological and thermal properties of the composites were analyzed by using FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (Scanning electron microscopy), BET (Brunauer-Emmett-Teller) surface area analysis and TGA (Thermogravimetric analysis) techniques.Öğe Synthesis and characterization of poly(o-toluidine)/kaolinite conductive composites for humidity and temperature sensing(PAMUKKALE UNIV, 2018) Boran, Filiz; Cetinkaya, Sevil; Karakisla, Meral; Sacak, MehmetConductive poly(o-toluidine)/kaolinite composite was synthesized via chemical polymerization of o-toluidine in the availability of kaolinite using ammonium persulfate as oxidizing agent. To investigate the use of the prepared conductive composite as humidity and temperature sensor, the effect of polymerization conditions such as HCl, o-toluidine and oxidant concentrations on the amount of conductive POT contained in the composite and the conductivity values of composites were investigated. It was found that the composites with the highest poly(o-toluidine) content (29.4%) and conductivity (8.3x10(-4) Scm(-1)) were obtained by 0.2 M ammonium persulfate, 0.4 M o-toluidine and 1 M hydrochloric acid for 2 hours of continuous polymerization at 20 degrees C. The resistivity values of pure poly(o-toluidine) and poly (o-toluidine)/kaolinite composite were monitored during heatingcooling cycles in the range of 0-100 degrees C. Changes in resistivity for pure poly(o-toluidine) and poly(o-toluidine)/kaolinite composite with humidity 30-90% were examined and humidity sensor behavior was determined. Characterization of the prepared composite was performed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy techniques (SEM).Öğe Synthesis of Conductive Polymer/Inorganic Material Composites and Characterization of Their Properties(AMER SCIENTIFIC PUBLISHERS, 2018) Anakli, Duygu; Cetinkaya, Sevil; Karakisia, MeralIn this work, conductive poly(2-ethyl aniline) (PEAn)/talc composite was prepared in the hydrochloric (HCl) medium by chemical polymerization of 2-ethyl aniline in the presence of talc using ammonium persulfate (APS) as oxidant. The effects of APS/EAn mole ratio on conductivity and PEAn amount of the PEAn/talc composite were investigated. The highest conductivity and the polymer yield of PEAn/Talc composite were obtained as 36.6% PEAn and 2.6x10(-7) S/cm, respectively. The structural, morphological and thermal properties of the conductive composites were characterized by using XRD, TGA, SEM and BET techniques. TGA results showed that the composite exhibited higher thermal stability than pure PEAn component.
