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The impact of segment dilution on the magnetic and hysteretic properties of ferrimagnetic (1/2-1) segmented Ising nanowire

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Communications in Theoretical Physics 2024年第7期76卷 145-155页

作者： ersin Kantar Sorgun Vocational School Yozgat Bozok UniversityYozgat 66700Turkey

This study explores the presence of diverse phase diagrams and hysteresis characteristics,as well as their dependencies on segment dilution,in an Ising-type core/shell segmented *** magnetic and hysteretic behavior of the nanostructure was carefully investigated by employing the effective-field theory and its respective diluted *** phase diagrams reveal characteristic phenomena that are influenced by the dilution ***,this study examined the variations in phase transitions and tricritical points by altering the dilution and physical parameters of the *** investigation also encompasses an examination of the hysteresis characteristics,including the hysteresis loop,coercivity,and remanence,in relation to the segment dilution dependence of the segmented *** was discovered that as the temperature rises,the hysteresis loop areas ***,intriguingly,at specific dilution and crystal area values,the hysteresis loop areas exhibit an augmentation.

关键词： segmented nanowire effective-field theory diluted effect phase diagrams hysteresis characteristics

Dynamic Forecasting of Traffic Event Duration in Istanbul:A Classification Approach with Real-Time Data Integration

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Computers, Materials & Continua 2024年第8期80卷 2259-2281页

作者： Mesut Ulu Yusuf Sait Türkan Kenan Menguc ersin Namlı Tarık Kucukdeniz Occupational Health and Safety Department Bandirma Onyedi Eylul UniversityBalikesir10200Türkiye Department of Industrial Engineering Istanbul University-CerrahpasaIstanbul34320Türkiye Department of Industrial Engineering Istanbul Technical UniversityIstanbul34467Türkiye

Today,urban traffic,growing populations,and dense transportation networks are contributing to an increase in traffic *** incidents include traffic accidents,vehicle breakdowns,fires,and traffic disputes,resulting in long waiting times,high carbon emissions,and other undesirable *** is vital to estimate incident response times quickly and accurately after traffic incidents occur for the success of incident-related planning and response *** study presents a model for forecasting the traffic incident duration of traffic events with high *** proposed model goes through a 4-stage process using various features to predict the duration of four different traffic events and presents a feature reduction approach to enable real-time data collection and *** the first stage,the dataset consisting of 24,431 data points and 75 variables is prepared by data collection,merging,missing data processing and data *** the second stage,models such as Decision Trees(DT),K-Nearest Neighbour(KNN),Random Forest(RF)and Support Vector Machines(SVM)are used and hyperparameter optimisation is performed with *** the third stage,feature selection and reduction are performed and real-time data are *** the last stage,model performance with 14 variables is evaluated with metrics such as accuracy,precision,recall,F1-score,MCC,confusion matrix and *** RF model outperforms other models with an accuracy of 98.5%.The study’s prediction results demonstrate that the proposed dynamic prediction model can achieve a high level of success.

关键词： Traffic event duration forecasting machine learning feature reduction shapley additive explanations(SHAP)

Magnetic hysteresis, compensation behaviors, and phase diagrams of bilayer honeycomb lattices

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Chinese Physics B 2015年第10期24卷 453-459页

作者： ersin Kantar Department of Physics Erciyes University

Magnetic behaviors of the Ising system with bilayer honeycomb lattice（BHL） structure are studied by using the effective-field theory（EFT） with correlations. The effects of the interaction parameters on the magnetic properties of the system such as the hysteresis and compensation behaviors as well as phase diagrams are investigated. Moreover, when the hysteresis behaviors of the system are examined, single and double hysteresis loops are observed for various values of the interaction parameters. We obtain the L-, Q-, P-, and S-type compensation behaviors in the system. We also observe that the phase diagrams only exhibit the second-order phase transition. Hence, the system does not show the tricritical point（TCP）.

关键词： bilayer honeycomb lattices effective-field theory magnetic hysteresis compensation behavior phase diagram

Unsupervised learning approach in defining the similarity of catchments:Hydrological response unit based k-means clustering,a demonstration on Western Black Sea Region of Turkey

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International Soil and Water Conservation Research 2020年第3期8卷 321-331页

作者： ersin Aytaç Zonguldak Bülent Ecevit University Department of Environmental Engineering67100ZonguldakTurkey

This study investigated the similarity of the catchments with the k-means clustering method by using the hydrological response unit(HRU)images of 33 catchments located in the Western Black Sea Region of *** are the unit cells in hydrological models and these units are important because the same HRUs have the same hydrological behavior regarding weather inputs and water *** that reside inside a cluster will have high hydrological similarity,the catchments of two separate clusters would be dissimilar to each *** the help of the clustered catchments,an elimination process can be conducted that can save time and effort in basin selection for future hydrological *** the study,the basic process sequence was carried out in 5 *** steps were creating HRUs,assigning a color to HRUs,creating HRU images,image embedding,and k-means clustering *** and multidimensional scaling plots were sketched to visually examine the quality of intra-cluster *** the silhouette score values,the optimum number of clusters was determined as 8,and the clustered catchments were illustrated on the study area.

关键词： HRU K-means clustering Multidimensional scaling Orange Silhouette score QSWAT+

An effective-field theory study of hexagonal Ising nanowire: Thermal and magnetic properties

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Chinese Physics B 2014年第4期23卷 465-471页

作者： Yusuf Kocakaplan ersin Kantar Institute of Science Erciyes University Department of Physics Erciyes University

By means of the effective-field theory （EFT） with correlations, the thermodynamic and magnetic quantities （such as magnetization, susceptibility, internal energy, specific heat, free energy, hysteresis curves, and compensation behaviors） of the spin-l/2 hexagonal Ising nanowire （HIN） system with core/shell structure have been presented. The hysteresis curves are obtained for different values of the system parameters, in both ferromagnetic and antiferromagnetic cases. It has been shown that the system only undergoes a second-order phase transition. Moreover, from the thermal variations of the total magnetization, the five compensation types can be found under certain conditions, namely the Q-, R-, S-, P-, and N-types.

关键词： hexagonal Ising nanowire effective-field theory hysteresis curve compensation behavior

Machine Learning and Classical Forecasting Methods Based Decision Support Systems for COVID-19

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Computers, Materials & Continua 2020年第9期64卷 1383-1399页

作者： RamazanÜnlü ersin Namlı Gumushane University BağlarbaşıMahGümüşhane29000Turkey Istanbul University-Cerrahpasa İstanbulÜniversitesi Avcılar Kampüsüİstanbul34320Turkey

From late 2019 to the present day,the coronavirus outbreak tragically affected the whole world and killed tens of thousands of *** countries have taken very stringent measures to alleviate the effects of the coronavirus disease 2019(COVID-19)and are still being *** this study,various machine learning techniques are implemented to predict possible confirmed cases and mortality numbers for the *** to these models,we have tried to shed light on the future in terms of possible measures to be taken or updating the current *** Vector Machines(SVM),Holt-Winters,Prophet,and Long-Short Term Memory(LSTM)forecasting models are applied to the novel COVID-19 *** to the results,the Prophet model gives the lowest Root Mean Squared Error(RMSE)score compared to the other three ***,according to this model,a projection for the future COVID-19 predictions of Turkey has been drawn and aimed to shape the current measures against the coronavirus.

关键词： Covid-19 machine learning time series forecasting

Hexagonal Type Ising Nanowire with Spin-1 Core and Spin-2 Shell Structure

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Communications in Theoretical Physics 2015年第10期64卷 401-408页

作者： Mehmet Ertas ersin Kantar Department of Physics Erciyes University

Thermodynamic properties and phase diagrams of a mixed spin-(1,2) Ising ferrimagnetic system with single ion anisotropy on hexagonal nanowire are studied by using effective-field theory with correlations. The susceptibility,internal energy and specific heat of the system are numerically examined and some interesting phenomena in these quantities are found. The effect of the Hamiltonian parameters on phase diagrams are examined in detail. Besides second-order phase transition, lines of first-order transition and tricritical points are found. In particular, we found that for some negative values of single-ion anisotropies, there exist first-order phase transitions.

关键词： hexagonal Ising nanowire mixed spin-(1 2) effectiv

REKF and RUKF for pico satellite attitude estimation in the presence of measurement faults

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Journal of Systems Engineering and Electronics 2014年第2期25卷 288-297页

作者： Halil ersin Sken Chingiz Hajiyev Department of Space and Astronautical Science The Graduate University for Advanced Studies (Sokendai) Aeronautics and Astronautics Faculty Istanbul Technical University

When a pico satellite is under normal operational condi- tions, whether it is extended or unscented, a conventional Kalman filter gives sufficiently good estimation results. However, if the measurements are not reliable because of any kind of malfunc- tions in the estimation system, the Kalman filter gives inaccurate results and diverges by time. This study compares two different robust Kalman filtering algorithms, robust extended Kalman filter （REKF） and robust unscented Kalman filter （RUKF）, for the case of measurement malfunctions. In both filters, by the use of de- fined variables named as the measurement noise scale factor, the faulty measurements are taken into the consideration with a small weight, and the estimations are corrected without affecting the characteristic of the accurate ones. The proposed robust Kalman filters are applied for the attitude estimation process of a pico satel- lite, and the results are compared.

关键词： pico satellite attitude estimation robust Kalman filter-ing extended Kalman filter (EKF) unscented Kalman filter (UKF).

Forecasting volatility in oil prices with a class of nonlinear volatility models:smooth transition RBF and MLP neural networks augmented GARCH approach

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Petroleum Science 2015年第3期12卷 534-552页

作者： Melike Bildirici zgÖrü ersin Department of Economics Yildiz Technical University Department of Economics Beykent University

In this study, the forecasting capabilities of a new class of nonlinear econometric models, namely, the LSTAR-LST-GARCH-RBF and MLP models are evalu- ated. The models are utilized to model and to forecast the daily returns of crude oil prices. Many financial time series are subjected to leptokurtic distribution, heavy tails, and nonlinear conditional volatility. This characteristic feature leads to deterioration in the forecast capabilities of tradi- tional models such as the ARCH and GARCH models. According to the empirical findings, the oil prices and their daily returns could be classified as possessing nonlinearity in the conditional mean and conditional variance processes. Several model groups are evaluated：（i） the models pro- posed in the first group are the LSTAR-LST-GARCH models that are augmented with fractional integration and asymmetric power terms （FIGARCH, APGARCH, and FIAPGARCH）; （ii） the models proposed in the second group are the LSTAR-LST-GARCH models further aug- mented with MLP and RBF type neural networks. The models are compared in terms of MSE, RMSE, and MAE criteria for in-sample and out-of-sample forecast capabili- ties. The results show that the LSTAR based and neural network augmented models provide important gains over the single-regime baseline GARCH models, followed by the LSTAR-LST-GARCH type models in terms of mod- eling and forecasting volatility in crude oil prices.

关键词： Volatility Petrol prices ARCH STAR Neural networks LSTAR-LST-GARCH family