In this study, for the loads supplied by three thermic plants, power of thermic plants, supplying... more In this study, for the loads supplied by three thermic plants, power of thermic plants, supplying the minimum values of the cost of energy used for an hour, have been found with Simulated Annealing (SA) which is a metaheuristic optimasition method. Firstly solution have been found with classical Lagrange Method. Later solution have also been found with SA algorithm. Solutions found with two different methods have been compared. And results found with SA have also been compared with the optimum results found with Genetic Algoritm. Results shows that using metaheuristic methods for specifying active power values have also been supplies saving at energy production cost.
Turkiye’de is sagligi ve guvenligi algisini ve bu konuda yurutulen tum calismalarin niteligini is... more Turkiye’de is sagligi ve guvenligi algisini ve bu konuda yurutulen tum calismalarin niteligini istenen seviyeye cikarmak adina yapilan bircok duzenleme bulunmaktadir. Is sagligi ve guvenligi konusunda son yillardaki A, B ve C sinifi uzmanlarinin sayisinin artmasi, ortak saglik guvenlik birimlerinin birbiri ardina kurulmasi, yasal mevzuatlarin kamu ve ozel sektor icin uygulamaya sokulmasi sektorun dinamik bir yapiya kavusmasini saglamistir. Ancak hizli bir gelisim ve degisim gosteren her alanda oldugu gibi, is sagligi ve guvenligi alaninda da bazi sorunlarin ortaya cikmasi kacinilmazdir. Is guvenligi profesyonellerini ve sorunlarini konu alan calismalara literaturde rastlanmasina karsin, kisisel ve cevresel bilesenlerin yapilan is sagligi ve guvenligi calismalarini hangi oranda etkiledigine dair yeterli bilimsel calismalar bulunmamaktadir. Bu calismada is guvenligi uzmanlarinin ozellikle risk analizi ve degerlendirme sureclerinde kisisel ve cevresel faktorlerden etkilenme duzeyleri a...
The steady state analysis of the cables under selected design and installation conditions provide... more The steady state analysis of the cables under selected design and installation conditions provide information to ensure that the cables remain within allowable operating temperature limits. Manufacturers share the ampacity levels and derating factors under certain conditions for the cables that they produced, depending on the standards. However, the diversity of conditions can increase in the real applications. In this study, ampacity comparisons have been carried out for a different design and environmental characteristics of an underground cable system. The selected parameters have been analyzed for steady-state conditions within certain ranges. Characteristic ampacity trend curves corresponding to the relevant parameter changes have been generated with iterative solutions.
Uyarlamalı düzleştirme metotları zaman serilerinin karakteristik değişimleri üzerindeki tahmin so... more Uyarlamalı düzleştirme metotları zaman serilerinin karakteristik değişimleri üzerindeki tahmin sonuçlarını iyileştirmek için önerilmişlerdir. Zaman içerisinde var olan uyarlamalı düzleştirme metotları çeşitlenmiştir. Birçoğu Trigg & Leach olarak isimlendirilen orijinal basit metottan çok farklı olup, doğruluğu artırmak için karmaşık mantıksal veya matematiksel önermeler içermektedir. Bu makalede Bulanık Ayarlamalı Üstel Düzleştirme olarak isimlendirilen yeni bir metot sunulmaktadır. Bu metot özellikle seviye kayması veya seviye kaymasıyla beraber aykırı sapmaların bulunduğu zaman serileri için tahmin doğruluğunun iyileştirilmesinde başarılıdır. Ampirik uygulama 'The M2-Competition Time Series' üzerinde gerçekleştirilmiştir. İstatistiksel analiz sonuçları tahmin doğruluğu açısından bu metodun klasik uyarlamalı üstel düzleştirme metodunu geride bıraktığını göstermektedir. Buna ek olarak önerilen metot diğer gelişmiş uyarlanabilir metotlarla karşılaştırıldığında oldukça basittir.
Abstract Solar radiation (SR) knowledge plays a vital role in the design, modelling, and operatio... more Abstract Solar radiation (SR) knowledge plays a vital role in the design, modelling, and operation of solar energy conversion systems and future energy investment policies of the governments. However, these data are not measured for all regions due to the non-availability of SR measurement equipment at the weather stations. Therefore, SR has to be accurately predicted using various prediction models. In this research, four models from different classes are being used to predict monthly average daily global SR data. The models used in this study are based on a machine-learning algorithm (feed-forward neural network), empirical models (3 Angstrom-type models), time series (Holt-Winters), and mathematical model (RSM). As the prediction locations, four provinces (Ankara, Karaman, Kilis, and Şirnak) in Turkey are selected. The dataset including pressure, relative humidity, wind speed, ambient temperature, and sunshine duration is supplied from the Turkish State Meteorological Service and it covers the years 2008–2018. In the study, monthly average daily global SR data for the year 2018 is being predicted, and the performance success of the models is discussed in terms of the following benchmarks R2, MBE, RMSE, MAPE, and t-stat. In the results, R2 value for all models is varying between 0.952 and 0.993 and MAPE and RMSE value for all models is smaller than 10% and 2 MJ/m2-day, respectively. Evaluation in terms of t-stat value, no models exceed the t-critic limit. Considering all the models together, ANN has presented the best results with an average R2, MBE, RMSE, MAPE, and t-stat of 0.9911, 0.1323 MJ/m2-day, 0.78 MJ/m2-day, 4.9263%, and 0.582, respectively. Then Holt-Winters, RSM, and empirical models closely followed it, respectively.
International Journal of Electrical Power & Energy Systems, 2021
Abstract The use of natural esters as an insulating liquid has become popular since the early 200... more Abstract The use of natural esters as an insulating liquid has become popular since the early 2000s. Studies in the literature emphasize the superiority of natural esters as compared to mineral oils. In these studies, the prominent properties of natural esters are presented as being environmentally friendly, safe, and delaying the aging of cellulosic insulation material. Although there is no doubt in terms of their characteristics, such as being environmentally and safe, exaggerated comments are made about the delay of aging of the paper material used in the insulation of transformer windings. This is because comparative experimental applications on mineral oil and natural esters are carried out under artificial and equal conditions provided in the laboratory environment. Whereas, performing these experiments on identical transformers will give more realistic results. In this study, two identical transformers were designed and equipped with precision fiber optic temperature sensors. Temperature differences that vary depending on the load between high voltage and low voltage windings were measured with a high degree of accuracy for both identical transformers. Besides these measurements, physical and chemical changes were analyzed on samples taken from insulation liquids. It was observed that the physical and chemical properties of the insulation liquids directly affect the operating performance of the transformers. Thanks to the differences in viscosity of insulating liquids, the heat dissipation due to losses in the windings were different for both transformers. Both heat distribution and temperature differences in the windings varied depending on the loading factors. Considering all these factors together, comprehensively evaluations were made on the aging rate of cellulosic insulation and the service life of the transformers.
International Review of Electrical Engineering, Feb 28, 2013
In recent years, many studies have been done on monitoring, analyzing and aging performance of po... more In recent years, many studies have been done on monitoring, analyzing and aging performance of power transformer which is one of the most important components of power system. It is important to know the loading capacitance and remaining service life of a transformer to ensure its economical and secured operation. In this study, a realistic method is presented for remaining service life prediction and life-loss calculation of the power transformers. The proposed method is applicable for all the power transformers and can be updated in the light of the relevant standards for the different liquid and solid insulation materials. As a case study, life-loss calculation and the remaining service life prediction is carried out using thermal model that has been created considering the parameters of the 250 MVA mineral oil–immersed power transformer
2015 3rd International Istanbul Smart Grid Congress and Fair (ICSG), 2015
This paper presents lifetime monitoring algorithm available for critical substation equipment. In... more This paper presents lifetime monitoring algorithm available for critical substation equipment. In the remaining life calculation stage, two proposed methods named the weighted moving average - based monitoring and the trend adjusted (double) exponential smoothing - based monitoring introduced, respectively. Both methods are evaluated for various cases and the validity of the first methods tested on the prototype transformer, experimentally. However, the second newly method has advantages such as wide forecast range, trend determination capability and insensitive to short term fluctuations. These methods with the algorithms are applicable for the instrument or its parts that aging characteristics can be expressed by the empirical equations under certain stress/stresses.
Gelismis ulkelerin onderliginde bircok ulkenin enerji piyasalarinda 90’li yillarin sonundan itiba... more Gelismis ulkelerin onderliginde bircok ulkenin enerji piyasalarinda 90’li yillarin sonundan itibaren hizli bir degisim gozlemlenmektedir. Bu degisim ozellesme sureclerine paralel olarak serbest piyasa yapisina gecis asamalarindan olusmaktadir. Yasal duzenleme ve mevzuatlarini hizla tamamlayan ulkeler bu konuda cok buyuk kazanimlar elde etmislerdir. Turkiye 2000’li yillarin baslarindan itibaren enerji alaninda bircok yapisal reforma imza atmistir. Ozel sektor yatirimlari bu surec icerisinde artan bir ivmeyle devam etmistir. 2015 yili itibariyle enerji borsasinin devreye girmesiyle, ozel sektorun katiliminin daha saglam temeller uzerine oturtulmasi saglanmistir. Ozellikle elektrik enerji piyasasi ozel sektor yatirimlarina daha acik, rekabetci, seffaf, arz-talep dengesinin saglandigi, tum paydaslarin yararini esas alan bir yapiya kavusturulmustur. Bu calismada genel olarak Dunya ve Turkiye’deki enerji piyasa yapilarinin gelisimine deginilmis, Turkiye ozelinde elektrik enerjisi piyasa y...
In this study, for the loads supplied by three thermic plants, power of thermic plants, supplying... more In this study, for the loads supplied by three thermic plants, power of thermic plants, supplying the minimum values of the cost of energy used for an hour, have been found with Simulated Annealing (SA) which is a metaheuristic optimasition method. Firstly solution have been found with classical Lagrange Method. Later solution have also been found with SA algorithm. Solutions found with two different methods have been compared. And results found with SA have also been compared with the optimum results found with Genetic Algoritm. Results shows that using metaheuristic methods for specifying active power values have also been supplies saving at energy production cost.
Turkiye’de is sagligi ve guvenligi algisini ve bu konuda yurutulen tum calismalarin niteligini is... more Turkiye’de is sagligi ve guvenligi algisini ve bu konuda yurutulen tum calismalarin niteligini istenen seviyeye cikarmak adina yapilan bircok duzenleme bulunmaktadir. Is sagligi ve guvenligi konusunda son yillardaki A, B ve C sinifi uzmanlarinin sayisinin artmasi, ortak saglik guvenlik birimlerinin birbiri ardina kurulmasi, yasal mevzuatlarin kamu ve ozel sektor icin uygulamaya sokulmasi sektorun dinamik bir yapiya kavusmasini saglamistir. Ancak hizli bir gelisim ve degisim gosteren her alanda oldugu gibi, is sagligi ve guvenligi alaninda da bazi sorunlarin ortaya cikmasi kacinilmazdir. Is guvenligi profesyonellerini ve sorunlarini konu alan calismalara literaturde rastlanmasina karsin, kisisel ve cevresel bilesenlerin yapilan is sagligi ve guvenligi calismalarini hangi oranda etkiledigine dair yeterli bilimsel calismalar bulunmamaktadir. Bu calismada is guvenligi uzmanlarinin ozellikle risk analizi ve degerlendirme sureclerinde kisisel ve cevresel faktorlerden etkilenme duzeyleri a...
The steady state analysis of the cables under selected design and installation conditions provide... more The steady state analysis of the cables under selected design and installation conditions provide information to ensure that the cables remain within allowable operating temperature limits. Manufacturers share the ampacity levels and derating factors under certain conditions for the cables that they produced, depending on the standards. However, the diversity of conditions can increase in the real applications. In this study, ampacity comparisons have been carried out for a different design and environmental characteristics of an underground cable system. The selected parameters have been analyzed for steady-state conditions within certain ranges. Characteristic ampacity trend curves corresponding to the relevant parameter changes have been generated with iterative solutions.
Uyarlamalı düzleştirme metotları zaman serilerinin karakteristik değişimleri üzerindeki tahmin so... more Uyarlamalı düzleştirme metotları zaman serilerinin karakteristik değişimleri üzerindeki tahmin sonuçlarını iyileştirmek için önerilmişlerdir. Zaman içerisinde var olan uyarlamalı düzleştirme metotları çeşitlenmiştir. Birçoğu Trigg & Leach olarak isimlendirilen orijinal basit metottan çok farklı olup, doğruluğu artırmak için karmaşık mantıksal veya matematiksel önermeler içermektedir. Bu makalede Bulanık Ayarlamalı Üstel Düzleştirme olarak isimlendirilen yeni bir metot sunulmaktadır. Bu metot özellikle seviye kayması veya seviye kaymasıyla beraber aykırı sapmaların bulunduğu zaman serileri için tahmin doğruluğunun iyileştirilmesinde başarılıdır. Ampirik uygulama 'The M2-Competition Time Series' üzerinde gerçekleştirilmiştir. İstatistiksel analiz sonuçları tahmin doğruluğu açısından bu metodun klasik uyarlamalı üstel düzleştirme metodunu geride bıraktığını göstermektedir. Buna ek olarak önerilen metot diğer gelişmiş uyarlanabilir metotlarla karşılaştırıldığında oldukça basittir.
Abstract Solar radiation (SR) knowledge plays a vital role in the design, modelling, and operatio... more Abstract Solar radiation (SR) knowledge plays a vital role in the design, modelling, and operation of solar energy conversion systems and future energy investment policies of the governments. However, these data are not measured for all regions due to the non-availability of SR measurement equipment at the weather stations. Therefore, SR has to be accurately predicted using various prediction models. In this research, four models from different classes are being used to predict monthly average daily global SR data. The models used in this study are based on a machine-learning algorithm (feed-forward neural network), empirical models (3 Angstrom-type models), time series (Holt-Winters), and mathematical model (RSM). As the prediction locations, four provinces (Ankara, Karaman, Kilis, and Şirnak) in Turkey are selected. The dataset including pressure, relative humidity, wind speed, ambient temperature, and sunshine duration is supplied from the Turkish State Meteorological Service and it covers the years 2008–2018. In the study, monthly average daily global SR data for the year 2018 is being predicted, and the performance success of the models is discussed in terms of the following benchmarks R2, MBE, RMSE, MAPE, and t-stat. In the results, R2 value for all models is varying between 0.952 and 0.993 and MAPE and RMSE value for all models is smaller than 10% and 2 MJ/m2-day, respectively. Evaluation in terms of t-stat value, no models exceed the t-critic limit. Considering all the models together, ANN has presented the best results with an average R2, MBE, RMSE, MAPE, and t-stat of 0.9911, 0.1323 MJ/m2-day, 0.78 MJ/m2-day, 4.9263%, and 0.582, respectively. Then Holt-Winters, RSM, and empirical models closely followed it, respectively.
In this study, for the loads supplied by three thermic plants, power of thermic plants, supplying... more In this study, for the loads supplied by three thermic plants, power of thermic plants, supplying the minimum values of the cost of energy used for an hour, have been found with Simulated Annealing (SA) which is a metaheuristic optimasition method. Firstly solution have been found with classical Lagrange Method. Later solution have also been found with SA algorithm. Solutions found with two different methods have been compared. And results found with SA have also been compared with the optimum results found with Genetic Algoritm. Results shows that using metaheuristic methods for specifying active power values have also been supplies saving at energy production cost.
Turkiye’de is sagligi ve guvenligi algisini ve bu konuda yurutulen tum calismalarin niteligini is... more Turkiye’de is sagligi ve guvenligi algisini ve bu konuda yurutulen tum calismalarin niteligini istenen seviyeye cikarmak adina yapilan bircok duzenleme bulunmaktadir. Is sagligi ve guvenligi konusunda son yillardaki A, B ve C sinifi uzmanlarinin sayisinin artmasi, ortak saglik guvenlik birimlerinin birbiri ardina kurulmasi, yasal mevzuatlarin kamu ve ozel sektor icin uygulamaya sokulmasi sektorun dinamik bir yapiya kavusmasini saglamistir. Ancak hizli bir gelisim ve degisim gosteren her alanda oldugu gibi, is sagligi ve guvenligi alaninda da bazi sorunlarin ortaya cikmasi kacinilmazdir. Is guvenligi profesyonellerini ve sorunlarini konu alan calismalara literaturde rastlanmasina karsin, kisisel ve cevresel bilesenlerin yapilan is sagligi ve guvenligi calismalarini hangi oranda etkiledigine dair yeterli bilimsel calismalar bulunmamaktadir. Bu calismada is guvenligi uzmanlarinin ozellikle risk analizi ve degerlendirme sureclerinde kisisel ve cevresel faktorlerden etkilenme duzeyleri a...
The steady state analysis of the cables under selected design and installation conditions provide... more The steady state analysis of the cables under selected design and installation conditions provide information to ensure that the cables remain within allowable operating temperature limits. Manufacturers share the ampacity levels and derating factors under certain conditions for the cables that they produced, depending on the standards. However, the diversity of conditions can increase in the real applications. In this study, ampacity comparisons have been carried out for a different design and environmental characteristics of an underground cable system. The selected parameters have been analyzed for steady-state conditions within certain ranges. Characteristic ampacity trend curves corresponding to the relevant parameter changes have been generated with iterative solutions.
Uyarlamalı düzleştirme metotları zaman serilerinin karakteristik değişimleri üzerindeki tahmin so... more Uyarlamalı düzleştirme metotları zaman serilerinin karakteristik değişimleri üzerindeki tahmin sonuçlarını iyileştirmek için önerilmişlerdir. Zaman içerisinde var olan uyarlamalı düzleştirme metotları çeşitlenmiştir. Birçoğu Trigg & Leach olarak isimlendirilen orijinal basit metottan çok farklı olup, doğruluğu artırmak için karmaşık mantıksal veya matematiksel önermeler içermektedir. Bu makalede Bulanık Ayarlamalı Üstel Düzleştirme olarak isimlendirilen yeni bir metot sunulmaktadır. Bu metot özellikle seviye kayması veya seviye kaymasıyla beraber aykırı sapmaların bulunduğu zaman serileri için tahmin doğruluğunun iyileştirilmesinde başarılıdır. Ampirik uygulama 'The M2-Competition Time Series' üzerinde gerçekleştirilmiştir. İstatistiksel analiz sonuçları tahmin doğruluğu açısından bu metodun klasik uyarlamalı üstel düzleştirme metodunu geride bıraktığını göstermektedir. Buna ek olarak önerilen metot diğer gelişmiş uyarlanabilir metotlarla karşılaştırıldığında oldukça basittir.
Abstract Solar radiation (SR) knowledge plays a vital role in the design, modelling, and operatio... more Abstract Solar radiation (SR) knowledge plays a vital role in the design, modelling, and operation of solar energy conversion systems and future energy investment policies of the governments. However, these data are not measured for all regions due to the non-availability of SR measurement equipment at the weather stations. Therefore, SR has to be accurately predicted using various prediction models. In this research, four models from different classes are being used to predict monthly average daily global SR data. The models used in this study are based on a machine-learning algorithm (feed-forward neural network), empirical models (3 Angstrom-type models), time series (Holt-Winters), and mathematical model (RSM). As the prediction locations, four provinces (Ankara, Karaman, Kilis, and Şirnak) in Turkey are selected. The dataset including pressure, relative humidity, wind speed, ambient temperature, and sunshine duration is supplied from the Turkish State Meteorological Service and it covers the years 2008–2018. In the study, monthly average daily global SR data for the year 2018 is being predicted, and the performance success of the models is discussed in terms of the following benchmarks R2, MBE, RMSE, MAPE, and t-stat. In the results, R2 value for all models is varying between 0.952 and 0.993 and MAPE and RMSE value for all models is smaller than 10% and 2 MJ/m2-day, respectively. Evaluation in terms of t-stat value, no models exceed the t-critic limit. Considering all the models together, ANN has presented the best results with an average R2, MBE, RMSE, MAPE, and t-stat of 0.9911, 0.1323 MJ/m2-day, 0.78 MJ/m2-day, 4.9263%, and 0.582, respectively. Then Holt-Winters, RSM, and empirical models closely followed it, respectively.
International Journal of Electrical Power & Energy Systems, 2021
Abstract The use of natural esters as an insulating liquid has become popular since the early 200... more Abstract The use of natural esters as an insulating liquid has become popular since the early 2000s. Studies in the literature emphasize the superiority of natural esters as compared to mineral oils. In these studies, the prominent properties of natural esters are presented as being environmentally friendly, safe, and delaying the aging of cellulosic insulation material. Although there is no doubt in terms of their characteristics, such as being environmentally and safe, exaggerated comments are made about the delay of aging of the paper material used in the insulation of transformer windings. This is because comparative experimental applications on mineral oil and natural esters are carried out under artificial and equal conditions provided in the laboratory environment. Whereas, performing these experiments on identical transformers will give more realistic results. In this study, two identical transformers were designed and equipped with precision fiber optic temperature sensors. Temperature differences that vary depending on the load between high voltage and low voltage windings were measured with a high degree of accuracy for both identical transformers. Besides these measurements, physical and chemical changes were analyzed on samples taken from insulation liquids. It was observed that the physical and chemical properties of the insulation liquids directly affect the operating performance of the transformers. Thanks to the differences in viscosity of insulating liquids, the heat dissipation due to losses in the windings were different for both transformers. Both heat distribution and temperature differences in the windings varied depending on the loading factors. Considering all these factors together, comprehensively evaluations were made on the aging rate of cellulosic insulation and the service life of the transformers.
International Review of Electrical Engineering, Feb 28, 2013
In recent years, many studies have been done on monitoring, analyzing and aging performance of po... more In recent years, many studies have been done on monitoring, analyzing and aging performance of power transformer which is one of the most important components of power system. It is important to know the loading capacitance and remaining service life of a transformer to ensure its economical and secured operation. In this study, a realistic method is presented for remaining service life prediction and life-loss calculation of the power transformers. The proposed method is applicable for all the power transformers and can be updated in the light of the relevant standards for the different liquid and solid insulation materials. As a case study, life-loss calculation and the remaining service life prediction is carried out using thermal model that has been created considering the parameters of the 250 MVA mineral oil–immersed power transformer
2015 3rd International Istanbul Smart Grid Congress and Fair (ICSG), 2015
This paper presents lifetime monitoring algorithm available for critical substation equipment. In... more This paper presents lifetime monitoring algorithm available for critical substation equipment. In the remaining life calculation stage, two proposed methods named the weighted moving average - based monitoring and the trend adjusted (double) exponential smoothing - based monitoring introduced, respectively. Both methods are evaluated for various cases and the validity of the first methods tested on the prototype transformer, experimentally. However, the second newly method has advantages such as wide forecast range, trend determination capability and insensitive to short term fluctuations. These methods with the algorithms are applicable for the instrument or its parts that aging characteristics can be expressed by the empirical equations under certain stress/stresses.
Gelismis ulkelerin onderliginde bircok ulkenin enerji piyasalarinda 90’li yillarin sonundan itiba... more Gelismis ulkelerin onderliginde bircok ulkenin enerji piyasalarinda 90’li yillarin sonundan itibaren hizli bir degisim gozlemlenmektedir. Bu degisim ozellesme sureclerine paralel olarak serbest piyasa yapisina gecis asamalarindan olusmaktadir. Yasal duzenleme ve mevzuatlarini hizla tamamlayan ulkeler bu konuda cok buyuk kazanimlar elde etmislerdir. Turkiye 2000’li yillarin baslarindan itibaren enerji alaninda bircok yapisal reforma imza atmistir. Ozel sektor yatirimlari bu surec icerisinde artan bir ivmeyle devam etmistir. 2015 yili itibariyle enerji borsasinin devreye girmesiyle, ozel sektorun katiliminin daha saglam temeller uzerine oturtulmasi saglanmistir. Ozellikle elektrik enerji piyasasi ozel sektor yatirimlarina daha acik, rekabetci, seffaf, arz-talep dengesinin saglandigi, tum paydaslarin yararini esas alan bir yapiya kavusturulmustur. Bu calismada genel olarak Dunya ve Turkiye’deki enerji piyasa yapilarinin gelisimine deginilmis, Turkiye ozelinde elektrik enerjisi piyasa y...
In this study, for the loads supplied by three thermic plants, power of thermic plants, supplying... more In this study, for the loads supplied by three thermic plants, power of thermic plants, supplying the minimum values of the cost of energy used for an hour, have been found with Simulated Annealing (SA) which is a metaheuristic optimasition method. Firstly solution have been found with classical Lagrange Method. Later solution have also been found with SA algorithm. Solutions found with two different methods have been compared. And results found with SA have also been compared with the optimum results found with Genetic Algoritm. Results shows that using metaheuristic methods for specifying active power values have also been supplies saving at energy production cost.
Turkiye’de is sagligi ve guvenligi algisini ve bu konuda yurutulen tum calismalarin niteligini is... more Turkiye’de is sagligi ve guvenligi algisini ve bu konuda yurutulen tum calismalarin niteligini istenen seviyeye cikarmak adina yapilan bircok duzenleme bulunmaktadir. Is sagligi ve guvenligi konusunda son yillardaki A, B ve C sinifi uzmanlarinin sayisinin artmasi, ortak saglik guvenlik birimlerinin birbiri ardina kurulmasi, yasal mevzuatlarin kamu ve ozel sektor icin uygulamaya sokulmasi sektorun dinamik bir yapiya kavusmasini saglamistir. Ancak hizli bir gelisim ve degisim gosteren her alanda oldugu gibi, is sagligi ve guvenligi alaninda da bazi sorunlarin ortaya cikmasi kacinilmazdir. Is guvenligi profesyonellerini ve sorunlarini konu alan calismalara literaturde rastlanmasina karsin, kisisel ve cevresel bilesenlerin yapilan is sagligi ve guvenligi calismalarini hangi oranda etkiledigine dair yeterli bilimsel calismalar bulunmamaktadir. Bu calismada is guvenligi uzmanlarinin ozellikle risk analizi ve degerlendirme sureclerinde kisisel ve cevresel faktorlerden etkilenme duzeyleri a...
The steady state analysis of the cables under selected design and installation conditions provide... more The steady state analysis of the cables under selected design and installation conditions provide information to ensure that the cables remain within allowable operating temperature limits. Manufacturers share the ampacity levels and derating factors under certain conditions for the cables that they produced, depending on the standards. However, the diversity of conditions can increase in the real applications. In this study, ampacity comparisons have been carried out for a different design and environmental characteristics of an underground cable system. The selected parameters have been analyzed for steady-state conditions within certain ranges. Characteristic ampacity trend curves corresponding to the relevant parameter changes have been generated with iterative solutions.
Uyarlamalı düzleştirme metotları zaman serilerinin karakteristik değişimleri üzerindeki tahmin so... more Uyarlamalı düzleştirme metotları zaman serilerinin karakteristik değişimleri üzerindeki tahmin sonuçlarını iyileştirmek için önerilmişlerdir. Zaman içerisinde var olan uyarlamalı düzleştirme metotları çeşitlenmiştir. Birçoğu Trigg & Leach olarak isimlendirilen orijinal basit metottan çok farklı olup, doğruluğu artırmak için karmaşık mantıksal veya matematiksel önermeler içermektedir. Bu makalede Bulanık Ayarlamalı Üstel Düzleştirme olarak isimlendirilen yeni bir metot sunulmaktadır. Bu metot özellikle seviye kayması veya seviye kaymasıyla beraber aykırı sapmaların bulunduğu zaman serileri için tahmin doğruluğunun iyileştirilmesinde başarılıdır. Ampirik uygulama 'The M2-Competition Time Series' üzerinde gerçekleştirilmiştir. İstatistiksel analiz sonuçları tahmin doğruluğu açısından bu metodun klasik uyarlamalı üstel düzleştirme metodunu geride bıraktığını göstermektedir. Buna ek olarak önerilen metot diğer gelişmiş uyarlanabilir metotlarla karşılaştırıldığında oldukça basittir.
Abstract Solar radiation (SR) knowledge plays a vital role in the design, modelling, and operatio... more Abstract Solar radiation (SR) knowledge plays a vital role in the design, modelling, and operation of solar energy conversion systems and future energy investment policies of the governments. However, these data are not measured for all regions due to the non-availability of SR measurement equipment at the weather stations. Therefore, SR has to be accurately predicted using various prediction models. In this research, four models from different classes are being used to predict monthly average daily global SR data. The models used in this study are based on a machine-learning algorithm (feed-forward neural network), empirical models (3 Angstrom-type models), time series (Holt-Winters), and mathematical model (RSM). As the prediction locations, four provinces (Ankara, Karaman, Kilis, and Şirnak) in Turkey are selected. The dataset including pressure, relative humidity, wind speed, ambient temperature, and sunshine duration is supplied from the Turkish State Meteorological Service and it covers the years 2008–2018. In the study, monthly average daily global SR data for the year 2018 is being predicted, and the performance success of the models is discussed in terms of the following benchmarks R2, MBE, RMSE, MAPE, and t-stat. In the results, R2 value for all models is varying between 0.952 and 0.993 and MAPE and RMSE value for all models is smaller than 10% and 2 MJ/m2-day, respectively. Evaluation in terms of t-stat value, no models exceed the t-critic limit. Considering all the models together, ANN has presented the best results with an average R2, MBE, RMSE, MAPE, and t-stat of 0.9911, 0.1323 MJ/m2-day, 0.78 MJ/m2-day, 4.9263%, and 0.582, respectively. Then Holt-Winters, RSM, and empirical models closely followed it, respectively.
Uploads
Papers by Yunus Biçen