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İptal
Bulunan: 24 Adet 0.002 sn
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Filtreler
Filtreler
Bulunan: 24 Adet 0.002 sn
Yayın Dili : en ✕Yazar/lar : DEMİR, Vahdettin ✕
Koleksiyon [3]
İlgili Araştırmacılar [20]
Ambargo Durumu [1]
Tam Metin [2]
Yayın Türü [3]
Yazar/lar [20]
Atıf Dizini [3]
Konu Başlıkları [20]
Yayıncı [20]
Yayın Tarihi [6]
Yayın Dili [1]
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
Erişime Açık

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
Erişime Açık

Drought and Flood Analyses of Samsun City

DEMİR, Vahdettin | BİLGE, Hümeyra | SEVİMLİ, Mehmet Faik

The aim of this study is to analyze the flood and drought based on precipitation and streamflow data gathered from Samsun City, the most developed province of the Black Sea Region. Flood and drought analysis are important for the water resources management and important for anticipating the natural disasters that may occur in Samsun. The study has been carried out in two parts. In the first part, streamflow data, covering the period from 1964 to 2015, provided by the Current Observation Station, which is the most powerful parameter causing flood, was investigated for flood analysis by Mann-Ken ...Daha fazlası

Konferans Bildirisi 2017 International Conference on Civil and Environmental Engineering 5 Görüntülenme
Erişime Açık

Numerical modeling of Samsun Mert River floods

ÜLKE, Aslı | BEDEN, Neslihan | DEMİR, Vahdettin | MENEK, Necati

Floods are considered one of the most important natural disasters after earthquakes in Turkey. As a result, there is currently great public interest in this issue and it is necessary to intensify research activities in order to understand natural disasters better and to reinforce risk management. The effect of climate change on meteorological events causes an increase in extreme events such as excessive precipitation in some regions. An extreme natural event becomes a disaster when it has a large impact on human settlements and activities. Study area Samsun city is placed in the north of Turke ...Daha fazlası

Makale 2017 European Water 4 Görüntülenme
Erişime Açık

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
Erişime Açık

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
Erişime Açık

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
Erişime Açık

Trend Analysis of Precipitation, Temperature and Wind Data in Samsun (Turkey)

ÜLKE, Aslı | BEDEN, Neslihan | DEMİR, Vahdettin

Climate change effects have been remarkably perceived today; the determination of trends in precipitation, stream flow, winds, evaporation, and temperatures has become considerable for the planning and management of water resources and engineering projects. Nowadays there is a lot of studies have been made in progress on global and regional climate changes in literature. The objective of this study is to analyze monthly, annual and seasonal trends in average temperature, total precipitation, and average wind data by Mann- Kendall, linear trend and Sen’s Trend tests. The data sets are obtained ...Daha fazlası

Konferans Bildirisi 2017 IWA 2nd Regional Symposium on Water, Wastewater and Environment 5 Görüntülenme
Erişime Açık

Flood Modeling of Samsun/Atakum Region by GIS Tools

BEDEN, Neslihan | DEMİR, Vahdettin | ÜLKE KESKİN, Aslı

Study area Samsun/Atakum province is almost under threat of flooding in each year. In this region, the main reason of devastating flood is the influence of the Degirmen stream especially during March, April, and July and due to seasonal rainfall, which eventually makes the district vulnerable to flooding. In addition, the human-based constructions and the collapse of water retaining structures are among the main causes of flooding. In this study flood risks of Samsun Degirmen stream determinate by MIKE 11 and GIS. Numerical model selection for studies provides advantages in developing and chan ...Daha fazlası

Makale 2018 JOURNAL OF NEW RESULTS IN SCIENCE (JNRS) 2 Görüntülenme
Erişime Açık

Flood Modeling by GIS Tools

BEDEN, Neslihan | DEMİR, Vahdettin | ÜLKE, Aslı

In this study flood risks of Samsun Degirmen stream determinate by MIKE 11 and GIS. In this study, MIKE powered by DHI software used for numerical 1D modeling of study area. The hydrological and hydraulic data for the study area were obtained from the Turkish General Directorate of State Hydraulic Works. ArcGIS program was used for creating a triangulated irregular network data (TIN). The flood inundation maps demonstrated that some areas, from the upstream to downstream of the Degirmen stream basin is affected from 100 year and 500 year return period events.

Konferans Bildirisi 2017 International Symposium on Multidisciplinary Studies and Innovative Technologies 4 Görüntülenme
Erişime Açık

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
Erişime Açık

Analysis of Annual, Seasonal, and Monhtly Trends of Climatic Data: A Case Study of Samsun

ÜLKE KESKİN, Aslı | BEDEN, Neslihan | DEMİR, Vahdettin

Climate change impacts are perceived today as being very noticeable; determination of precipitation, wind, flow, evaporation and temperature trends has become essential for water resources and engineering projects in management and planning. Nowadays there is a lot of studies have been made in progress on global and regional climate changes in literature. In this study, monthly, annual and seasonal trends in average temperature, total precipitation, and average wind speed data calculated by Mann-Kendall, linear trend and Sen’s trend tests. The gauge station is located in Samsun, which is the l ...Daha fazlası

Makale 2018 Nature Sciences 4 Görüntülenme
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