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Characterization and corrosion studies of ternary Zn–Ni–Sn alloys

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International Journal of Minerals,Metallurgy and Materials 2020年第1期27卷 74-82页

作者： Reyhan Solmaz B.Deniz karahan Department of Metallurgical and Materials Engineering Istanbul Technical UniversityMaslakIstanbul 34469Turkey School of Engineering and Natural Sciences Istanbul Medipol UniversityBeykozIstanbul 34810Turkey

Nine distinct zinc-nickel-tin films with different compositions have been galvanostatically electrodeposited. The films have been characterized by scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS). Their corrosion potentials and densities have been estimated using Tafel extrapolation. Next, the electrochemical behaviors of the films(deposited through the electrolytes containing 0, 6, 8, and10 g/L SnCl2?6H2O) have been examined based on cyclic voltammetry(CV) measurements. Further, these films have been immersed in 3.5 wt%Na Cl solution for 1 h, 1 d, 7 d, 14 d, 28 d, and 42 d followed by application of Tafel extrapolation and electrochemical impedance spectroscopy(EIS) tests on each aged sample. Finally, to analyze the morphologies and the compositions of the oxide films covering the surfaces of the 42-d aged films, FT-IR and SEM analyses have been performed. The results indicated that the Zn–Ni–Sn film produced through the bath including 6g/L SnCl2?6H2 O exhibits superior corrosion resistance because of the high Ni content in the presence of Sn that promotes the barrier protection capability of the deposit.

关键词： ternary alloys corrosion electro galvanizing anomalous deposition Tafel

Effect of Coriolis and centrifugal forces on flow and heat transfer at high rotation number and high density ratio in non orthogonally internal cooling channel

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Chinese Journal of Aeronautics 2017年第1期30卷 216-234页

作者： brahim Berrabah Miloud Aminallah Department of Mechanical Engineering Materials and Reactive Systems Laboratory Faculty of Technology Djillali Liabes University Sidi Bel-Abbes 22000 Algeria

Numerical predictions of three-dimensional flow and heat transfer are performed for a two-pass square channel with 45° staggered ribs in non-orthogonally mode-rotation using the second moment closure model. At Reynolds number of 25,000, the rotation numbers studied were 0,0.24, 0.35 and 1.00. The density ratios were 0.13, 0.23 and 0.50. The results show that at high buoyancy parameter and high rotation number with a low density ratio, the flow in the first passage is governed by the secondary flow induced by the rotation whereas the secondary flow induced by the skewed ribs was almost distorted. As a result the heat transfer rate is enhanced on both co-trailing and co-leading sides compared to low and medium rotation number. In contrast, for the second passage, the rotation slightly reduces the heat transfer rate on co-leading side at high rotation number with a low density ratio and degrades it significantly on both co-trailing and co-leading sides at high buoyancy parameter compared to the stationary, low and medium rotation numbers. The numerical results are in fair agreement with available experimental data in the bend region and the second passage, while in the first passage were overestimated at low and medium rotation numbers.

关键词： Blade cooling Computational FluidDynamic (CFD) Heat transfer High buoyancy parameter High rotation number

Massive self-duality solution associated with invariant one-forms

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Chinese Physics C 2018年第1期42卷 71-74页

作者： brahim Sener seyh samil mahallesi P. B. 06824 Eryaman Etimesgut - Ankara / TURKEY

A massive self-duality solution associated with invariant 1-forms is presented. At the zero mass limit the massive self-dual theory of the SO（3） gauge group on 4 dimensions cannot be reduced to that of massless *** such a case the self-dual connection turns to the flat connection and one cannot obtain a massless theory in such an approach.

关键词： massive gauge fields self-duality invariant one-forms

Mc Kean–Vlasov BSDEs with Locally Monotone Coefficient

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Acta Mathematica Sinica,English Series 2023年第7期39卷 1414-1424页

作者： brahim BOUFOUSSI Soufiane MOUCHTABIH LIBMA Faculty of Sciences SemlaliaCadi Ayyad University2390 MarrakeshMorocco École Supérieure de Technologie d'El Kelaa des Sraghna UniversitéCadi AyyadRoute de Béni Mellal Km 8 B.P.104El Kelaa des SraghnaMorocco

We consider a McKean Vlasov backward stochastic differential equation(MVBSDE) of the form Y_(t)=-F(t,Y_(t),Z_(t),[Y_(t)]) dt+Z_(t) dB_(t),Y_(T)=ξ,where [Y_(t)] stands for the law of Y,.We show that if F is locally monotone in y,locally Lipschitz with respect to z and law's variable,and the monotonicity and Lipschitz constants κ_(n),L_(n) are such that L_(n)^(2)+κ_(n)^(+)=O(log(N)),then the MVBSDE has a unique stable solution.

关键词： McKean–Vlasov BSDE locally monotone coefficient stability

An artificial neural network approach for prediction of long-term strength properties of steel fiber reinforced concrete containing fly ash

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第11期9卷 1514-1523页

作者： Okan karahan Harun TANYILDIZI Cengiz D. ATIS Civil Engineering Department Erciyes University Construction Education Department Fιrat University

In this study, an artificial neural network (ANN) model for studying the strength properties of steel fiber reinforced concrete (SFRC) containing fly ash was devised. The mixtures were prepared with 0 wt%, 15 wt%, and 30 wt% of fly ash, at 0 vol.%, 0.5 vol.%, 1.0 vol.% and 1.5 vol.% of fiber, respectively. After being cured under the standard conditions for 7, 28, 90 and 365 d, the specimens of each mixture were tested to determine the corresponding compressive and flexural strengths. The pa- rameters such as the amounts of cement, fly ash replacement, sand, gravel, steel fiber, and the age of samples were selected as input variables, while the compressive and flexural strengths of the concrete were chosen as the output variables. The back propagation learning algorithm with three different variants, namely the Levenberg-Marquardt (LM), scaled conjugate gradient (SCG) and Fletcher-Powell conjugate gradient (CGF) algorithms were used in the network so that the best approach can be found. The results obtained from the model and the experiments were compared, and it was found that the suitable algorithm is the LM algorithm. Furthermore, the analysis of variance (ANOVA) method was used to determine how importantly the experimental parameters affect the strength of these mixtures.

关键词： Fly ash Steel fiber Strength properties Artificial neural network (ANN) Analysis of variance (ANOVA) method

TWO DIMENSIONAL MELLIN TRANSFORM IN QUANTUM CALCULUS

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Acta Mathematica Scientia 2018年第2期38卷 546-560页

作者： Kamel brahim Latifa RIAHI Faculty of Sciences of Tunis. University of Tunis El Manar Tunisia

In this article, we introduce the two dimensional Mellin transform M4（f）（s,t）, give some properties, establish the Paley-Wiener theorem and Plancherel formula, present the Hausdorff-Young inequality, and find seve... 详细信息

关键词： Quantum calculus Two dimensional Mellin transform q-Double integral

Efects of Die Corner Radius and Temperature on the Formability of AA7075-T6 Alloy

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Acta Metallurgica Sinica(English Letters) 2013年第5期26卷 623-629页

作者： Hatice Evlen brahim Kad Mustafa Ya sar Technology Faculty Karabuk University

This study focused on the formability of aluminium alloy（7075-T6） sheets through hydroforming route. Formability of these sheets was tested using a warm forming setup at three diferent temperatures and four diferent die corner radii. Forming limit diagrams（FLD） were generated by measuring the grids of the sheet formed. The results show that the forming limit of AA7075-T6 can be significantly improved when the blank was heated to 140–250℃. It was also observed that as the temperature increases above 140℃, dome height began to decrease. Also the results indicated that both the die corner radius and temperature have a significant efect on the stress-strain curve and warm forming of AA7075-T6 sheets. Thus, with the temperature increased from room temperature（RT） to 140℃, the flow stress decreased and the strain increased, hence, the formability is enhanced. However, further increase in temperature causes decreases the flow stress and strain. Similar changes of the flow curve were seen in die corner radius. Decreasing the die corner radius decreases the flow stress and increase the strain. Moreover, an equation was obtained by establishing correlations between the experimental parameters and their results. In this way, it became possible to make predictions.

关键词： Al-Zn-Mg-Cu Alloy Drawing process Formability Forming limit curve Deformation

Assessment of some chemical element contents in Traganum nudatum Del shrub using instrumental neutron activation analysis

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Nuclear Science and Techniques 2015年第4期26卷 46-50页

作者： Bouzid Nedjimi brahim Beladel Laboratory of Exploration and Valuation of the Steppe Ecosystem Faculty of Science of Nature and Life University of Djelfa University of Djelfa

Instrumental neutron activation analysis(INAA)has been used to determine some chemical element contents(K,Ca,Na,Fe,Zn,Co,Eu,Sb,and Sc)in Traganum nudatum Del(Chenopodiaceae family)consumed in North African rangelands by sheep *** were collected from the area of Djelfa in an arid steppe of *** show that pasture halophyte had sufficient levels of K,Ca,Zn,and Co to meet the requirements of ***,it seems that this halophyte shrub had substantial amounts of Na,higher than the critical level established by the National Research Council(NRC).Eu,Sb,and Sc were within the safety baseline of all the assayed elements recommended by the *** high Na content(～10 g/kg)in this halophytic species requires elevated intake of water by livestock.

关键词：仪器中子活化分析化学元素含量灌木评价盐生植物阿尔及利亚钙水平 INAA

Comparison of the Retinomax hand-held autorefractor versus table-top autorefractor and retinoscopy

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International Journal of Ophthalmology(English edition) 2014年第3期7卷 491-495页

作者： Ibrahim Tuncer Mehmet Ozgur Zengin Eyyup karahan Alfagoz Eye Center Department of Ophthalmology Izmir University Faculty of Medicine

AIM:To compare noncycloplegic and cycloplegic results of Retinomax measurements with findings achieved after cycloplegia using table-top autorefractor and ***:The study included 127 patients(mean age96.7mo,range 21 to 221).Retinomax(Rmax)(Nikon Inc.,Japan)was used to obtain noncycloplegic *** cycloplegia,refraction was measured with Rmax,table-top autorefractor(TTR)(Nikon NRK 8000,Inc.,Japan)and *** values of sphere,spherical equivalent,cylinder and axis of cylinder were recorded for Rmax,TTR and retinoscopy in each *** results were analyzed ***:The mean spheric values(SV),spherical equivalent values(SEV)and cylindrical values(CV)of the noncycloplegic Rmax(SV:0.64 D,SEV:0.65 D and CV:0.03 D,respectively)were found to be significantly lower than cycloplegic TTR(1.43 D,1.38 D and 0.3 D;P=0.012,P=0.011 and P=0.04,respectively)and retinoscopy(1.34 D,1.45 D and 0.23 D;P=0.04,P=0.002 and P=0.045,respectively).Mean cycloplegic SV,SEV,CV were not significantly different between Rmax and TTR,Rmax and retinoscopy,TTR and *** or noncycloplegic axis values were not different between any ***:Rmax may be used successfully as a screening tool but may not be accurate enough for actual spectacle *** Rmax measurements may be able to identify refractive error in children because of approximate results to retinoscopy.

关键词： autorefractor hand-held refractors retinoscopy Retinomax