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Application of Markovian models for non-ergodic and non-stationary earthquake times series for the identification of seismic patterns and future projections

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Earthquake Science 2020年第2期33卷 98-106页

作者： hakan Karaca Department of Architecture Omer Halisdemir UniversityNigde 51240Turkey

The current earthquake forecast algorithms are not free of shortcomings due to inherent ***,the requirement of stationarity in the evaluation of earthquake time series as a prerequisite,significantly limits the use of forecast algorithms to areas where stationary data is not *** shortcoming of forecast algorithms is the ergodicity assumption,which states that certain characteristics of seismicity are spatially *** this study,a new earthquake forecast approach is introduced for the locations where stationary data are not *** this purpose,the spatial activity rate density for each spatial unit is evaluated as a parameter of a Markov *** temporal pattern is identified by setting the states at certain spatial activity rate *** using the transition patterns between the states,1-and 5-year forecasts were *** method is suggested as an alternative and complementary to the existing methods by proposing a solution to the issues of ergodicity and stationarity assumptions at the same time.

关键词： spatial pattern Markov chain spatially smoothed seismicity seismic activity rate

MULTIPLIERS AND TENSOR PRODUCTS OF L(p,q) LORENTZ SPACES

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Acta Mathematica Scientia 2007年第1期27卷 107-116页

作者： hakan Avci A.Turan Gürkanli Department of Mathematics Faculty of Arts and Sciences Ondokuz Mayis University55139KurupelitSamsunTURKEY

Let G be a locally compact abelian group. The main purpose of this article is to find the space of multipliers from the Lorentz space. L（p1, q1）（G） to L（p＇2, q＇2）（G）. For this reason, the authors define the space A p1,q1^ p2,p2（G）, discuss its properties and prove that the space of multipliers from L（p1, q1）（G） to L（p＇2, q＇2）（G） is isometrically isomorphic to the dual of A p1,q1^p2,q2 （G）.

关键词： Lorentz space Banach module multiplier

Phase Field Modelling Allotropic Transformation of Solid Solution

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Computers, Materials & Continua 2020年第3期62卷 1289-1302页

作者： Yaochan Zhu Hua Qiu hakan Hallberg Xi’an Aeronautical Polytechnic Institute Xi’an710089China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Solid Mechanics Lund University22100LundSweden

Based on multiphase field conception and integrated with the idea of vector-valued phase field,a phase field model for typical allotropic transformation of solid solution is *** model takes the non-uniform distribution of grain boundaries of parent phase and crystal orientation into account in proper way,as being illustrated by the simulation of austenite to ferrite transformation in low carbon *** is found that the misorientation dependent grain boundary mobility shows strong influence on the formation of ferrite morphology comparing with the weak effect exerted by misorientation dependent grain boundary *** evolution of various types of grain boundaries are quantitatively characterized in terms of its respective grain boundary energy *** simulated ferrite fraction agrees well with the expectation from phase diagram,which verifies this model.

关键词： Phase field allotropic transformation grain boundary misorientation

Effects of Material Properties and Punch Tip Radius on Spring-Forward in 90° V Bending Processes

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Journal of Iron and Steel Research International 2013年第10期20卷 64-69页

作者： Dilipak hakan zdemir Mustafa Sarikaya Murat Manufacturing Department Technology FacultyGazi University Mechanical Education Institute of Science and TechnologyGazi University Machine and Metal Technology Department Vocational High SchoolSinop University

Bending process is one of the most significant fields of application of sheet metal die. Sheet metals are ex posed to some spring back or spring-forward depending on elastic deformation following bending process. S235JR （1. 003 8） materials having a thickness of 4 mm were bent with 90° punches having 5 different tip radiuses. The ben- ding process was carried out by making the punch waited on the material for 30 s （30 s wait bending） and by remo ving the punch without waiting （direct bending）. Specimens were prepared in three forms as non-heat-treated, nor- malized and tempered. At the same time, all experiments were performed at a deformation speed of 25 mm/min. As a result, it was determined that as punch tip radius increased, the amount of spring-forward decreased. Although normalizing process applied to specimens increased the amount of spring-forward, tempering process decreased it. The amount of spring-forward was decreased in 30 s wait bending process.

关键词： spring-forward V die bending metal forming heat treatment

Initialisation of a hybrid AC/DC power system for harmonic stability analysis using a power flow formulation

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High Voltage 2020年第5期5卷 534-542页

作者： Aleksandra Lekić hakan Ergun Jef Beerten Department of Electrical Engineering(ESAT-ELECTA) KU LeuvenLeuvenBelgium

This study presents the initialisation of a hybrid alternating current/direct current(AC/DC)power system to determine the operation point around which the system is linearised as a starting point for an electromagnetic or harmonic stability *** this end,each AC or DC power system component is modelled in the Fourier transform domain and further adjusted to a simplified representation compatible with a power flow *** study also presents how voltage source converter(VSC)high-voltage DC-based systems can be analysed when the different VSC controls are *** result of the power flow solution is then used for the power converters’initialisation.

关键词： AC/DC system formulation

Alternative scattering kernels for the first estimates of a reactor:diffusion length

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Nuclear Science and Techniques 2018年第3期29卷 86-91页

作者： hakan Oztürk Ayca Simsek Yapar Department of Physics Faculty of Arts and SciencesOsmaniye Korkut Ata University80000 OsmaniyeTurkey

Diffusion-length calculations of neutrons are performed using the Chebyshev polynomials of the second kind. The neutrons are assumed to move with constant energy in a uniform homogeneous slab. An alternative scattering kernel called an Anl?–Gngr phase function and a traditional Henyey–Greenstein phase function are used for the scattering function in the stationary neutron transport equation. First, analytic expressions and then numerical results are obtained for the diffusion length for various values of the scattering and cross-sectional *** results obtained from both scattering kernels for the diffusion length of the neutrons are given in tables side by side for comparison. The applicability of the method is easily demonstrated by these results.

关键词： Scattering kernel Diffusion length Chebyshev polynomials Transport equation

R/S ratio in lead Ⅱ, and the prognostic significance of red cell distribution width in acute coronary syndrome

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World Journal of Clinical Cases 2019年第16期7卷 2217-2226页

作者： Abuzer Coskun Sevki hakan Eren Department of Emergency Sivas Numune HospitalSivas 58040Turkey Department of Emergency Medicine Gaziantep University School of MedicineGaziantep 27310Turkey

BACKGROUND In spite of developing medical technologies to discover the etiopathogenesis of diseases and developments in the treatment of coronary artery disease, acute coronary syndromes(ACS) continue to be the main cause of mortality and morbidity worldwide. New cardiac biomarkers and techniques are needed to help provide rapid diagnosis in order to evaluate risk in coronary artery *** To evaluate the effects of R to S ratio(RSR) in the electrocardiograph of patients with ACS, from the point of the arising complication after myocardial infarction(MI), to three-vessel disease(TVD) and *** The data of 1,296 patients with ACS, who presented to the emergency department of our hospital with chest pain between January 2014 and December2018 and were admitted to the cardiology clinic, were retrospectively included in this cross-sectional cohort study. Patients with an RSR value less than I were assigned to group Ⅰ, while those with an RSR value greater than Ⅰ were assigned to group Ⅱ.RESULTS In our study, 466(35.9%) of the 1,296 patients, 357(38.3%) in group 1 and 109(29.9%) in group 2, were female, with a mean age of 61.56 ± 9.42. ST-elevation MI 573(44.2%), unstable angina(UA) 502(38.7%) and non ST-elevation MI 220(17%)were more prevalent in group Ⅰ. Acute anterior MI 263(20.3) in group Ⅰ, and acute inferior MI 184(14.2) in group Ⅱ was higher. Ischemic heart failure was the most common complication. In group Ⅱ, the red cell distribution width(RDW) was 15.42 ± 1.82, the gensini score was 48.39 ± 36.44, the left ventricular ejection fraction was 41.17 ± 10.41, the TVD was 111(8.5), and the mortality rate was 72(5.6), which was significantly higher than group Ⅰ RDW; in MI with ST and nonST-elevation, in TVD, mortality and complications were high and low in UA. In single and multivariate regression analyses, the variables were associated with ACS *** RSR levels may be an auxiliary predictive value in ACS in terms of complications developing

关键词： Acute coronary syndrome Emergency department R/S ratio Red cell distribution width

An efficient stock market prediction model using hybrid feature reduction method based on variational autoencoders and recursive feature elimination

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Financial Innovation 2021年第1期7卷 585-608页

作者： hakan Gunduz Software Engineering Department Bandirma Onyedi Eylul University10200 BalikesirTurkey

In this study,the hourly directions of eight banking stocks in Borsa Istanbul were predicted using linear-based,deep-learning(LSTM)and ensemble learning(Light-GBM)*** models were trained with four different feature sets and their performances were evaluated in terms of accuracy and F-measure *** the first experiments directly used the own stock features as the model inputs,the second experiments utilized reduced stock features through Variational AutoEncoders(VAE).In the last experiments,in order to grasp the effects of the other banking stocks on individual stock performance,the features belonging to other stocks were also given as inputs to our *** combining other stock features was done for both own(named as allstock_own)and VAE-reduced(named as allstock_VAE)stock features,the expanded dimensions of the feature sets were reduced by Recursive Feature *** the highest success rate increased up to 0.685 with allstock_own and LSTM with attention model,the combination of allstock_VAE and LSTM with the attention model obtained an accuracy rate of *** the classification results achieved with both feature types was close,allstock_VAE achieved these results using nearly 16.67%less features compared to allstock_*** all experimental results were examined,it was found out that the models trained with allstock_own and allstock_VAE achieved higher accuracy rates than those using individual stock *** was also concluded that the results obtained with the VAE-reduced stock features were similar to those obtained by own stock features.

关键词： Stock market prediction Variational autoencoder Recursive feature elimination Long-short term memory Borsa Istanbul LightGBM

Seismic Tomography and Surface Wave Analysis Based Methodologies on Evaluation of Geotechnical Properties of Volcanic Rocks: A Case Study

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Journal of Earth Science 2014年第2期25卷 348-356页

作者： Ali Erden Babacan Kenan Gelisli hakan Ersoy Karadeniz Technical University Department of Geophysics Engineering

Economic development, industrialization and dense population in Trabzon City have caused residential construction to increase by 300% in the last decade. The settlement area is moun- tainous and covered with heavy vegetation. Thus, the steep-sided topography and heavy precipita- tion means floods and landslides are common and in areas with little flat land. Since the mass movements in some parts of city create an enormous danger for buildings, site selection for residen- tial areas becomes increasingly important. This paper describes geotechnical and seismic properties of Tertiary volcanic rock and establishes the link between these units and construction. In this study, refraction tomography and multichannel analysis surface wave methods were applied in order to seek the best construction site in the residential area. The results of the geophysical study were com- pared with the borehole applications. A series of geomechnical tests were carried out on the core samples. Following that, statistical correlations were conducted by regression analysis to evaluate re- lationships between measured parameters. Rock Quality Designation and weathering degree were also determined. The methodology defined in this investigation proves to be an appropriate ap- proach to determine geotechnical properties of the foundation rocks and soils and a proper guide on future geotechnical studies for other cities.

关键词： Trabzon City Turkey refraction tomography MASW ultrasonic geotechnical.