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Öğe Application of Artificial Neural Network-Based Approach for Calculating Dissolved Oxygen Profiles in Kapulukaya Dam Reservoir(Centre Environment Social & Economic Research Publ-Ceser, 2007) Tüzün, İlhami; Soyupak, Selçuk; İnce, Özlem; Başaran, GökbenAn Artificial Neural Network (ANN) modelling approach has been shown to be successful in calculating time and space dependent dissolved oxygen (DO) concentration profiles in Kapulukaya Dam Reservoir using limited number of input variables. The variation of inflow to the reservoir with respect to time was significantly high. The reservoir operational levels were relatively stable. The Levenberg-Marquardt algorithm was adopted during training. Preprocessing before training and post processing after simulation steps were the treatments applied to raw data and predictions respectively. Different configurations of Multilayer perceptron neural networks were designed by selecting different combinations of number of hidden layers (single and double) and number of neurons within each of the hidden layers. Generalisation was improved and over-fitting problems were eliminated: Early stopping method was applied for improving generalisation. The conventional model criteria of correlation coefficient (R) and mean square errors (MSE) were adopted to compare model performances. The correlation coefficients between neural network estimates and field measurements were as high as 0.96 for daily and monthly data respectively with experiments that involve double layer neural network structure with 31 neurons within each hidden layer. The study results revealed that the data sizes effect model performances up to a certain level.Öğe An automata networks based preprocessing technique for artificial neural network modelling of primary production levels in reservoirs(Elsevier, 2007) Kılıç, Hürevren; Soyupak, Selçuk; Tüzün, İlhami; İnce, Özlem; Başaran, GökbenPrimary production in lakes and reservoirs develops as a result of complex reactions and interactions. Artificial neural networks (ANN) emerges as an approach in quantification of primary productivity in reservoirs. Almost all of the past ANN applications employed input data matrices whose vectors represent either water quality parameters or environmental characteristics. Most of the time, the components of input matrices are determined using expert opinion that implies possible factors that affect output vector. Major disadvantage of this approach is the possibility of ending-up with an input matrix that may have high correlations between some of its components. In this paper, an automata networks (AN) based preprocessing technique was developed to select suitable and appropriate constituents of input matrix to eliminate redundancy and to enhance calculation efficiency. The proposed technique specifically provides an apriori rough behavioral modeling through identification of minimal AN interaction topology. Predictive ANN models of primary production levels were developed for a reservoir following AN based pre-modeling step. The achieved levels of model precisions and performances were acceptable: the calculated root mean square error values (RMSE) were low; a correlation coefficient (R) as high as 0.83 was achieved with an ANN model of a specific structure. (c) 2006 Elsevier B.V. All rights reserved.Öğe Eymir gölünde biyomanipulasyon uygulamasının fiziksel, kimyasal ve biyolojik parametrelerle takibi(Kırıkkale Üniversitesi, 2002) İnce, Özlem; Beklioğlu, Meryem; Tüzün, Y.İlhamiÖZET EYMİR GÖLÜ'NDE BİYOMANİPULASYON UYGULAMASININ FİZİKSEL, KİMYASAL VE BİYOLOJİK PARAMETRELERLE TAKİBİ İNCE, Özlem Kırıkkale Üniversitesi Fen Bilimleri Enstitüsü Biyoloji Anabilim Dalı, Yüksek Lisans Tezi Danışman : Yrd. Doç. Dr. İlhamı TÜZÜN Ortak Danışman : Doç. Dr. Meryem Beklioğlu Şubat 2002, 76 sayfa Bu çalışmada, Ankara'nın 20 km güneyinde yer alan Eymir Gölü'nde, Ağustos 1998 tarihinde başlatılan biyomanipulasyon çalışmasının sonuçları değerlendirilmiştir. Uzun süre yüksek miktarda dış kaynaklı besin tuzu yüklemesine maruz kalan Eymir Gölü, yoğun fitoplankton biyokütlesiyle bulanık su konumunun gözlendiği ötrofik bir göl haline gelmiştir. 1994 yılında yüklerin önemli bir kısmı uzaklaştırılmış olmasına rağmen, halen devam eden yükleme, iyileşmeyi engellemiştir. Yaptığımız çalışmada, gölde besin zincirinde yukarıdan aşağıya olan kontrolün, planktivor balık uzaklaştırılması suretiyle etkin hale getirilmesi amaçlanmıştır. Bu uygulamanın sonucu olarak gölün bitkice zengin berrak su konumuna geçmesi öngörülmüştür.Çalışma süresince gölün girdilerinde, çıktısında ve göliçi istasyonunda yapılan örneklemelerle, fiziksel ve kimyasal değişkenler analiz edilmiş, fitoplankton ve zooplankton populasyonlarındaki değişimler belirlenmiştir. Makrofit yayılışı, yavru ve ergin balık stok tayinlerinin de yapıldığı çalışmada elde edilen veriler doğrultusunda, gölde biyomanipulasyon sonrası iyileşmenin göstergesi olarak ortalama klorofıl-a miktarında düşüşler, sualtı bitki yayılışında, zooplankton, (özellikle Daphnia sp.) miktarında ve ortalama Secchi derinliğinde artışlar olduğu tespit edilmiş, bitki yayılışı haricindeki diğer değişkenlerdeki değişimler istatistiki olarak da önemli bulunmuştur. Toplam fosfor (TP) ve çözünebilir reaktif fosfor (SRP) konsantrasyonlarında ise beklenenin aksine belirgin artışlar saptanmıştır. Biyomanipulasyonu takip eden yılda bitki yayılışının yeterli düzeye ulaşamaması ve klorofil-a konsantrasyonları ile Daphnia sp. yoğunluğundaki düzensiz iniş çıkışlar, göldeki iyileşmenin yavaş olduğuna işaret etmiştir. Bunun, gölden uzaklaştırılan balık miktarının yetersiz olması ve biyomanipulasyon sonrasında yeni yıl genç balık bireylerinin artmasından kaynaklandığı sonucuna varılmıştır. Ayrıca, göle halen yüksek miktarlarda giren dış kaynaklı yüklerin besin zincirinde aşağıdan yukarıya olan etkisinin, yapılmak istenen değişikliklerin (yukarıdan aşağıya kontrolün) yavaşlamasında önemli rol oynadığı saptanmıştır. Bu çalışmayla elde edilen sonuçlar itibariyle, gölde alınması gereken ilave önlemlerin tartışması yapılmıştır. Anahtar Kelimeler : Eymir Gölü, Ötrofikasyon, Biyomanipulasyon, Besin Tuzları, Fitoplankton, Zooplankton, Planktivor Balık, Sualtı bitkileriÖğe Relationship between water flow volume and in-lake total phosphorus concentrations via dissolved oxygen concentrations and temperature in a warm temperate reservoir: Implications by path analysis(2006) Tüzün, İlhami; İnce, ÖzlemThe effects of water inflow-outflow volumes on the in-lake total phosphorus (TP) concentrations was investigated for the deep, stratified Çubuk II Dam Lake. The fluctuations in the TP concentrations followed a seasonal pattern, with lower values found during the summer, and peak values during wet seasons. Both the seasonal pattern and the horizontal/vertical heterogeneities in the TP concentrations were usually found to be in accordance with those of the water flow parameters. The vertical differences in the TP concentrations provided evidence that an interflow formed at the 5 m and 10 m depths by the water inflow resulted in higher mean TP concentrations at these depths. In contrast, the water outflows had a reducing effect on the TP concentrations, particularly at the 15 m depth, by promoting net TP export. Although the horizontal distribution of the TP concentrations differed slightly between the riverine, transition and lacustrine zones, the differences did not indicate any statistical significance (P>0.05, multivariate analysis of variance). The path analysis performed on the vertical data proved to be a promising tool in estimating the direct correlations between water flow dynamics and TP concentrations when the decomposition of indirect correlations via dissolved oxygen concentrations and temperature was accounted for in these mutual associations. © 2006 Blackwell Publishing Asia Pty Ltd.Öğe Utilisation of native, heat and acid-treated microalgae Chlamydomonas reinhardtii preparations for biosorption of Cr(VI) ions(Elsevier Sci Ltd, 2005) Arica, M. Yakup; Tüzün, İlhami; Yalçın, Emine; İnce, Özlem; Bayramoğlu, GülayThe hexavalent chromium biosorption onto native, heat- and acid-treated Chlamydomonas reinhardtii was studied from aqueous solutions. Biosorption equilibrium was established in about 120 min. The surface properties of the microalgae preparations varied with pH, and the maximum absorption of chromium ions on the microalgae preparations was obtained at pH 2.0. The biosorption of chromium ions by the microalgae preparations increased as the initial concentration of chromium ions increased in the medium. The maximum biosorption capacities of the native, heat- and acid-treated algal preparations were 18.2, 25.6 and 21.2 mg Cr(VI) per g of dry biosorbents, respectively. Equilibrium concentration (q(m)) and dissociation constant (K-d) were calculated by fitting the experimental data with the Langmuir isotherms. The chromium adsorption data were analysed using the first- and the second-order kinetic models. The experimental results suggest that the second-order equation is the most appropriate equation to predict the biosorption capacities of all the biosorbents. All the tested algal preparations could be regenerated using 0.1 M NaOH solution, with up to 96% recovery. (c) 2004 Elsevier Ltd. All rights reserved.
