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Bulunan: 16 Adet 0.001 sn
Atıf Dizini : Scopus ✕İlgili Araştırmacılar : Vahdettin Demir ✕
Koleksiyon [3]
İlgili Araştırmacılar [20]
Ambargo Durumu [1]
Tam Metin [2]
Yayın Türü [2]
Yazar/lar [20]
Atıf Dizini [2]
Konu Başlıkları [20]
Yayıncı [12]
Yayın Tarihi [6]
Yayın Dili [2]
Doç. Dr. Vahdettin DemirKTO KARATAY ÜNİVERSİTESİ/MÜHENDİSLİK VE DOĞA BİLİMLERİ FAKÜLTESİ/İNŞAAT MÜHENDİSLİĞİ BÖLÜMÜ/İNŞAAT MÜHENDİSLİĞİ PR. (TAM BURSLU)/
Erişime Açık

Forecasting of solar radiation using different machine learning approaches

DEMİR, Vahdettin | ÇITAKOĞLU, Hatice

In this study, monthly solar radiation (SR) estimation was performed using five different machine learning-based approaches. The models used are support vector machine regression (SVMR), long short-term memory (LSTM), Gaussian process regression (GPR), extreme learning machines (ELM) and K-nearest neighbors (KNN). Modeling of these approaches was carried out in two stages. In the first stage, VIF analysis was carried out to develop the model. Thus, the input parameters that decrease the performance of the model are removed. In the second stage, remaining input parameters such as meteorological ...Daha fazlası

Makale 2022 Neural Computing and Applications 6 Görüntülenme
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Water level change of lakes and sinkholes in Central Turkey under anthropogenic effects

DEMİR, Vahdettin | ÜLKE KESKİN, Aslı

Determining water level changes in lakes is significant for sustainable water supply planning, flood control, water resource management, and economic development with ecosystem sustainability. Trend analysis is a commonly used tool for detecting changes in hydrologic time series of quantities such as lake level, precipitation and temperature. Trend analysis of meteorological variables is very important for assessing the long-term changes in lake levels. This study examines long-term changes in the lakes in the Central Anatolia region of Turkey. Kızören and Timraş sinkhole lakes and Lakes Tuz a ...Daha fazlası

Makale 2020 Theoretical and Applied Climatology 3 Görüntülenme
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Hybrid Adaptive Neuro-Fuzzy Models for Water Quality Index Estimation

YASEEN, Zaher Mundher | RAMAL, Majeed Mattar | DIOP, Lamine | JAAFAR, Othman | DEMİR, Vahdettin | KİŞİ, Özgür

Soft computing models are known as an efficient tool for modelling temporal and spatial variation of surface water quality variables and particularly in rivers. These model’s performance relies on how effective their simulation processes are accomplished. Fuzzy logic approach is one of the authoritative intelligent model in solving complex problems that deal with uncertainty and vagueness data. River water quality nature is involved with high stochasticity and redundancy due to the its correlation with several hydrological and environmental aspects. Yet, the fuzzy logic theory can give robust ...Daha fazlası

Makale 2018 Springer Netherlands 9 Görüntülenme
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Trend analysis of lakes and sinkholes in the Konya Closed Basin, in Turkey

DEMİR, Vahdettin

This study aims to investigate the trend of water-level changes in lakes (Lake Tuz and Lake Beyşehir) and sinkholes (Timraş and Kızören) in the Konya Closed Basin located in Turkey. Water-level changes in these lakes and sinkholes were investigated along with changes in meteorological parameters (precipitation, temperature, and evaporation) and groundwater trends that indicate the climate in the region. Several statistical tests can be used to determine the signifcance of hydrological trends over time. These tests are divided into two categories: parametric and nonparametric. In this study, th ...Daha fazlası

Makale 2022 Natural Hazards 4 Görüntülenme
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Trend Analyses of Meteorological Variables and Lake Levels for Two Shallow Lakes in Central Turkey

YAĞBASAN, Özlem | DEMİR, Vahdettin | YAZICIGİL, Hasan

Trend analyses of meteorological variables play an important role in assessing the long-term changes in water levels for sustainable management of shallow lakes that are extremely vulnerable to climatic variations. Lake Mogan and Lake Eymir are shallow lakes offering aesthetic, recreational, and ecological resources. Trend analyses of monthly water levels and meteorological variables affecting lake levels were done by the Mann-Kendall (MK), Modified Mann-Kendall (MMK), Sen Trend (ST), and Linear trend (LT) methods. Trend analyses of monthly lake levels for both lakes revealed an increasing tre ...Daha fazlası

Makale 2020 Water 8 Görüntülenme
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Developing numerical equality to regional intensity–duration–frequency curves using evolutionary algorithms and multi‑gene genetic programming

ÇITAKOĞLU, Hatice | DEMİR, Vahdettin

This study aims to carry out regional intensity−duration−frequency (IDF) equality using the relationship with IDF obtained from point frequency analysis. Eleven empirical equations used in the literature for seven climate regions of Turkey were calibrated using particle swarm optimization (PSO) and genetic algorithm (GA) optimization techniques and the obtained results were compared. In addition, in this study, new regional IDF equations were obtained for each region utilizing MultiGene Genetic Programming (MGGP) method. Finally, Kruskal–Wallis (KW) test was applied to the IDF values obtained ...Daha fazlası

Makale 2022 Acta Geophysica 6 Görüntülenme
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Impacts of climatic variables on water-level variations in two shallow Eastern Mediterranean lakes

YAĞBASAN, Özlem | YAZICIGİL, Hasan | DEMİR, Vahdettin

Variations in temperature and precipitation have direct impacts on the physical, chemical and biological characteristics of the shallow lakes. This paper examines the possible linkages between climate variables and the water levels of shallow interconnected Lakes Mogan and Eymir, located 20 km south of Ankara in Central Anatolia. The variations in the lakes' water levels during 1996-2015 are studied and the impacts of climate variables on the lake levels are assessed to address the long-term consequences. The nonparametric Mann-Kendall test was used to quantify trends in the climate variables ...Daha fazlası

Makale 2017 ENVIRONMENTAL EARTH SCIENCES 8 Görüntülenme
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Neurocomputing intelligence models for lakes water level forecasting: a comprehensive review

DEMİR, Vahdettin | YASEEN, Zaher Mundher

Hydrological processes forecasting is an essential step for better water management and sustainability. Among several hydrological processes, lake water level (LWL) forecasting is one of the significant processes within a particular catchment. The complexity of the LWL fluctuation is owing to the diversity of the influential parameters including climate, hydrology and some other morphology. In this study, several versions of neurocomputing intelligence models are developed for LWL fluctuation forecasting at five great lakes Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario, ...Daha fazlası

Makale 2022 Neural Computing and Applications 9 Görüntülenme
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Hydrological Time Series Forecasting Using Three Different Heuristic Regression Techniques

KİŞİ, Özgür | SHIRI, Jalal | DEMİR, Vahdettin

The ability of three different heuristic regression methods, least-square support vector regression (LSSVR), multivariate adaptive regression spline (MARS), and M5 model tree (M5Tree), was investigated in forecasting hydrological time series. In the study, daily streamflow data from two stations in Turkey were used by employing cross validation method. Models were compared with each other with respect to root-mean-square error, mean absolute error and determination coefficient. The LSSVR was found to be superior to the MARS and M5Tree models in daily streamflow forecasting. The effect of perio ...Daha fazlası

Kitap Bölümü 2017 Elsevier Inc. 3 Görüntülenme
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Obtaining the Manning roughness with terrestrialremote sensing technique and flood modeling using FLO-2D: A case study Samsun from Turkey

DEMİR, Vahdettin | ÜLKE KESKİN, Aslı

Flooding is one of the most catastrophic events among the wide spectrum of natural disasters that impact human communities. The identification of floodprone areas and the probability of occurrence, or estimated return period, of flood events are fundamental to proper planning for flood management and minimization of the social and economic costs of flood damage. In this study, 1D/2D coupled flood models of the Mert River, which flows into the Black Sea at Samsun in north-central Turkey, were developed. Based on the flood modeling results, flood extent, flood depth and flood hazard maps for the ...Daha fazlası

Makale 2020 Geofizika 6 Görüntülenme
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Modeling of air pollutants using least square support vector regression, multivariate adaptive regression spline, and M5 model tree models

KİŞİ, Özgür | PARMAR, Kulwinder | SONI,Kirti | DEMİR, Vahdettin

This study investigates the applicability of three different soft computing methods, least square support vector regression (LSSVR), multivariate adaptive regression splines (MARS), and M5 Model Tree (M5-Tree), in forecasting SO2 concentration. These models were applied to monthly data obtained from Janakpuri, Nizamuddin, and Shahzadabad, located in Delhi, India. The models were compared with each other using the cross validation method with respect to root mean square error, mean absolute error, and correlation coefficient. According to the comparison, LSSVR provided better accuracy than the ...Daha fazlası

Makale 2017 Springer Netherlands 2 Görüntülenme
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Türkiye’nin uzun dönem ortalama sıcaklık (°C) değerlerinin üç farklı enterpolasyon yöntemi ile tahmini

YILMAZ, Cavit Berkay | BODU, Hilal | YÜCE, Ethem Sabri | DEMİR, Vahdettin | SEVİMLİ, Mehmet Faik

Bu çalışmada, Türkiye'nin uzun vadeli aylık ortalama sıcaklıkları üç farklı enterpolasyon yöntemi kullanılarak tahmin edilmiştir. Sıcaklıklar komşu ölçüm istasyonlarına ait enlem-boylam özellikleri ve Ters Mesafe Ağırlıklı Enterpolasyon yöntemi (Inverse Distance Weighting, IDW), Kriging ve Radyal Tabanlı Fonksiyon (Radial Basis Function, RBF) yöntemleri kullanılarak tahmin edilmiştir. Yöntemler ArcGIS yazılımı altında ArcMAP programı ile uygulanmıştır. Çalışmada 2 farklı enterpolasyon parametresi kullanılmıştır. Bunlar; Enlem (Derece) ve Boylam (Derece) şeklindedir. Veriler 1981-2020 yılları a ...Daha fazlası

Makale 2021 Geomatik 4 Görüntülenme
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