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Effects of Tungsten and Boron Contents on Crystallization Temperature and Microhardness of Tungsten Based Metallic Glasses

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 733-738页

作者： pelin ztürk Aytekin Hitit Department of Materials Science and Engineering AfyonKocatepe University

Effects of tungsten and boron contents on the thermal properties and microhardness of W-Fe-B metallic glass system were studied. Thin foils, with thicknesses of 20 and 100 ktm, of the alloys were produced by piston and anvil method in an arc furnace. The structures of the foils were investigated by X-ray diffraction. Thermal stabilities of the alloys were examined by using differential scanning calorimetry. 20-μm- thick foils of all the alloys were determined to be fully amorphous, but crystalline phases were detected in the 100-μm-thick foils. It was found that crystallization temperatures of the alloys are between 1060 and 1177 K. Tungsten and boron content increases improve the crystallization temperature and microhardness of the alloys significantly, but deteriorate the glass forming ability of the alloys. It was also observed that for constant Fe content, increasing tungsten content to the level higher than that of boron content does not result in any further improvement in crystallization temperature, but improves glass forming ability significantly. The alloy containing highest total amount of tungsten and boron, W35Fe35B3o, has the highest crystallization temperature, 1177 K, and microhardness, 1634 HV.

关键词： Metallic glass Refractory metal Crystallization temperature Hardness

Numerical investigation of seismic performance of high modulus columns under earthquake loading

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Earthquake Engineering and Engineering Vibration 2019年第4期18卷 811-822页

作者： Selcuk Demir pelin Ozener Abant Izzet Baysal University Bolu 14030 Turkey Yildiz Technical University Istanbul 34210 Turkey

This paper presents the result of two-dimensional fi nite element modeling studies in order to investigate the seismic behavior of high modulus columns in liquefi able soil. Particular attention was paid to the shear stress reduction mechanism of the high modulus columns and the shear strain distribution between soil and columns during earthquake motion. Numerical analyses were performed using a nonlinear elasto-plastic model in Plaxis 2016. The reliability of the numerical simulations was verifi ed through the results of a centrifuge test model designed to investigate the contribution of high modulus columns in liquefaction mitigation. The capability of numerical simulations was assessed primarily through comparison of predicted acceleration-time histories, pore water pressures, and displacements with the measured counterparts. The results of the numerical analysis showed that the presence of the columns did not reduce seismic shear stresses in the soil when compared to the unimproved soil condition and pure shear behavior between soil and column did not develop as expected in the current design methodology.

关键词： liquefaction high modulus column soil improvement UBC3D-PLM

An Ordinal Multi-Dimensional Classification(OMDC)for Predictive Maintenance

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Computer Systems Science & Engineering 2023年第2期44卷 1499-1516页

作者： pelin Yildirim Taser Izmir Bakircay University Department of Computer EngineeringIzmir35665Turkey

Predictive Maintenance is a type of condition-based maintenance that assesses the equipment's states and estimates its failure probability and when maintenance should be *** machine learning techniques have been frequently implemented in this area,the existing studies disregard to the nat-ural order between the target attribute values of the historical sensor ***,these methods cause losing the inherent order of the data that positively affects the prediction *** deal with this problem,a novel approach,named Ordinal Multi-dimensional Classiﬁcation(OMDC),is proposed for estimating the conditions of a hydraulic system's four components by taking into the natural order of class *** demonstrate the prediction ability of the proposed approach,eleven different multi-dimensional classiﬁcation algorithms(traditional Binary Relevance(BR),Classiﬁer Chain(CC),Bayesian Classiﬁer Chain(BCC),Monte Carlo Classiﬁer Chain(MCC),Probabilistic Classiﬁer Chain(PCC),Clas-siﬁer Dependency Network(CDN),Classiﬁer Trellis(CT),Classiﬁer Dependency Trellis(CDT),Label Powerset(LP),Pruned Sets(PS),and Random k-Labelsets(RAKEL))were implemented using the Ordinal Class Classiﬁer(OCC)***,seven different classiﬁcation algorithms(Multilayer Perceptron(MLP),Support Vector Machine(SVM),k-Nearest Neighbour(kNN),Decision Tree(C4.5),Bagging,Random Forest(RF),and Adaptive Boosting(AdaBoost))were chosen as base learners for the OCC *** experimental results present that the proposed OMDC approach using binary relevance multi-dimensional classiﬁcation methods predicts the conditions of a hydraulic system's multiple components with high ***,it is clearly seen from the results that the OMDC models that utilize ensemble-based classiﬁcation algorithms give more reliable prediction performances with an average Hamming score of 0.853 than the others that use traditional algorithms as base learners.

关键词： Machine learning multi-dimensional classiﬁcation ordinal classiﬁcation predictive maintenance

Estimation of residual shear strength ratios of liquefied soil deposits from shear wave velocity

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Earthquake Engineering and Engineering Vibration 2012年第4期11卷 461-484页

作者： pelinzener Yildiz Technical University Davutpasa CampusDepartment of Civil Engineering

For sites susceptible to liquefaction induced lateral spreading during a probable earthquake, geotechnical engineers often need to know the undrained residual shear strength of the liquefied soil deposit to estimate lateral spreading displacements, and the forces acting on the piles from the liquefied soils in order to perform post liquefaction stability analyses. The most commonly used methods to estimate the undrained residual shear strength （Su~） of liquefied sand deposits are based on the correlations determined from liquefaction induced flow failures with SPT and CPT data. In this study, 44 lateral spread case histories are analyzed and a new relationship based on only lateral spread case histories is recommended, which estimates the residual shear strength ratio of the liquefiable soil layer from normalized shear wave velocity. The new proposed method is also utilized to estimate the residual lateral displacement of an example bridge problem in an area susceptible to lateral spreading in order to provide insight into how the proposed relationship can be used in geotechnical engineering practice.

关键词： liquefaction lateral spread undrained residual shear strength undrained residual shear strength ratio shearwave velocity

Microplastics in municipal wastewater treatment plants: a case study of Denizli/Turkey

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Frontiers of Environmental Science & Engineering 2023年第8期17卷 95-105页

作者： pelin Koyuncuoğlu Gülbin Erden Environmental Engineering Department Engineering FacultyPamukkale UniversityKınıklıCampusDenizli 20160Turkey

Plastic particles smaller than 5 mm are *** are among the significant pollutants that recently attracted *** quantities of microplastics enter the sewage system daily and reach wastewater treatment plants(WWTPs).As a result,WWTPs are potential microplastic ***,they create a pathway for microplastics to reach aquatic environments with treated wastewater *** on microplastic characterization in WWTPs have gained momentum in *** study investigates the abundance,size,shape,color,polymer type,and removal efficiencies of microplastics in a municipal wastewater treatment plant(WWTP)in Denizli/*** results showed that the dominant microplastic shape in wastewater samples was fibers(41.78%–60.77%)in the 100–500μm(58.57%–80.07%)size *** of the microplastics were transparent-white(32.86%–58.93%).The dominant polymer types were polyethylene(54.05%)and polyethylene vinyl acetate(37.84%)in raw ***,the microplastic removal efficiencies of the Denizli Central WWTP as a whole and for individual treatment units were *** the microplastic pollution removal efficiency of the Denizli Central WWTP was over 95%,the microplastic concentration discharged daily into the receiving environment was considerably high(1.28×1010 MP/d).Thus,Denizli Central WWTP effluents result in a high volume of emissions in terms of microplastic pollution with a significant daily discharge to theÇürüksu Stream.

关键词： Microplastics Wastewater treatment plant Removal efficiency Daily discharge

Piezoelectric d_(15) shear response-based torsion actuation mechanism:an experimental benchmark and its 3D finite element simulation

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International Journal of Smart and Nano Materials 2010年第3期1卷 224-235页

作者： pelin Berik Ayech Benjeddou Institute of Technical Mechanics Johannes Kepler University of LinzLinzAustria Institut Supérieur de Mécanique de Paris(Supméca) ParisFrance

An experimental benchmark is proposed for piezoelectric,direct-torsion actuation using mono-morph piezoceramic d_(15)shear *** is reached by designing and assembling an adaptive plate having two identical composite faces sandwiching a core made of connected six oppositely polarized(OP)piezoceramic d15 shear patches along the *** electronic speckle pattern interferometry system was used to measure the static tip deflection of the adaptive sandwich composite plate that was mounted in a cantilever configuration and actuated in torsion by progressively applied voltages on the piezoceramic shear core electroded major ***,the effective rate of twist was post-processed and proposed as an evaluation criterion for smart composites under piezoelectric torsion *** verification of the experimental results,the proposed experimental benchmark was simulated using three-dimensional piezoelectric finite elements(FE)within ABAQUS®commercial *** comparison of the obtained experimental and simulation results showed reasonable agreement,but the slight nonlinear experimental response was not confirmed by the linear FE *** experimentally proved torsion actuation mechanism,produced by OP piezoceramic d15 shear patches,can be applied actively to prevent torsion in many applications,such as in wind turbines,helicopter blades,robot arms,flexible space structures,etc.

关键词： torsion actuation shear-mode piezoceramic benchmark experiment simulation

Static experimentations of the piezoceramic d_(15)-shear actuation mechanism for sandwich structures with opposite or same poled patches-assembled core and composite faces

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International Journal of Smart and Nano Materials 2011年第4期2卷 230-244页

作者： pelin Berik Ayech Benjeddou Institute of Technical Mechanics Johannes Kepler University of LinzLinzAustria Institut Supérieur de Mécanique de Paris(Supméca) ParisFrance

Static d_(15)-shear actuated smart composites consisting of glass fiber/epoxy layers sandwiching piezoceramic shear patches-assembled cores were investigated experimentally and *** piezoceramic cores were formed by connecting two or three patches with the same or opposite polarization *** each cantilevered benchmark the shear-induced transverse tip deflection,under increasing actuation voltage,ranging from 61.5 V to 198 V,was measured by an electronic speckle pattern interferometer *** performance of the shear actuated smart composites was characterized by their shear-induced transverse deflection per length per *** was found that this performance is much better at high voltages for which the response becomes *** verification of the experimental results the proposed benchmarks were simulated within ABAQUS®commercial code using three-dimensional piezoelectric finite *** comparison of the obtained experimental and simulation results show a nonlinear dependence of the transverse deflection for voltages higher than around 92 V.

关键词： piezoceramic d_(15)-shear static actuation smart composite

Uniform convergence of the p-Bieberbach polynomials in domains with zero angles

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Science China Mathematics 2015年第5期58卷 1063-1078页

作者： ABDULLAYEV Fahreddin G ZKARTEPE pelin N Department of Mathematics Faculty of Arts and Science Mersin University

Let G C C be a simply connected domain whose boundary L ：= G is a Jordan curve and 0 ∈ G. Let w = φ（z） be the conformal mapping of G onto the disk B（0, r0）：= {w ：｜w｜〈 r0）, satisfying φ0（0） = 0, φ＇t（0） = 1. We consider the following extremal problem for p 〉 0：∫∫G｜φ＇（z）-P＇n（z）｜Pdσz→min in the class of all polynomials Pn（z） of degree not exceeding n with Pn（0） = 0, P＇n （0）=- 1. The solution to this extremal problem is called the p-Bieberbach polynomial of degree n for the pair （G, 0）. We study the uniform convergence of the p-Bieberbach polynomials Bn,p（z） to the φ（z） on G^- with interior and exterior zero angles determined depending on the properties of boundary arcs and the degree of their ＂touch＂.

关键词： conformal mapping quasiconformal curve Bieberbach polynomials complex approximation

Changes of total antioxidant capacity and total oxidant status of aqueous humor in diabetes patients and correlations with diabetic retinopathy

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International Journal of Ophthalmology(English edition) 2013年第4期6卷 531-536页

作者： Emrullah Beyazyildiz Ali Bülent ankaya Esra Ergan Mustafa Alparslan Anayol Yasemin zdamar Sevilay Sezer Mehmet Hakan Tirhis pelin Yilmazbas Faruk ztürk Department of Ophthalmology Gazi Mustafa Kemal State HospitalAnkara 06900Turkey Department of Ophthalmology Ulucanlar Eye Research and Training HospitalAnkara 06900Turkey Department of Ophthalmology Van Government HospitalVanAnkara 06900Turkey Department of Biochemistry Numune Research and Training HospitalAnkara 06900Turkey

AIM:To measure changes of total oxidant status(TOS)and total antioxidant capacity(TAC) of aqueous humor(AH) in diabetic retinopathy(DR) patients,and to determine if there were any differences in TOS and TAC of AH in diabetic patients without retinopathy compared with non-diabetic patients.·METHODS:One hundred and three eyes of 103patients who were enrolled for cataract surgery were included in this *** were grouped according to presence of diabetes and stage of *** to cataract surgery,0.1mL to 0.2mL of AH was aspirated and analyzed for TAC and TOS level using a colorimetric method.·RESULTS:TOS levels were highest among proliferative diabetic retinopathy(PDR) patients and lowest in patients with only *** were statistically significant between all groups(P <0.05).Whereas result between diabetic without retinopathy patients and non-proliferative diabetic retinopathy(NPDR) patients was not statistically significant(P =0.757).TAC levels were highest in patients with only cataract and lowest among PDR patients and results were statistically significant between all groups(P <0.05).·CONCLUSION:Aqueous humor TAC levels are low in diabetic patients and reduced further in DR patients,TOS levels are increased in diabetic patients and this is exacerbated in DR patients.

关键词： aqueous humor diabetic retinopathy total antioxidant capacity total oxidant status