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Nano Research 2010年第9期3卷 676-684页

作者： önder metin SaimÖzkar Shouheng Sun Department of Chemistry Middle East Technical University06531AnkaraTurkey Department of Chemistry Brown UniversityProvidenceRhode Island 02912USA

Monodisperse Ni nanoparticles(NPs)have been synthesized by the reduction of nickel(Ⅱ)acetylacetonate with the borane–tributylamine complex in a mixture of oleylamine and oleic *** Ni NPs are an active catalyst for the hydrolysis of the ammonia–borane(AB,H3N⋅BH3)complex under ambient conditions and their activities are dependent on the chemical nature of the oxide support that they were deposited *** various oxides(SiO_(2),Al_(2)O_(3),and CeO_(2))tested,SiO_(2)was found to enhance Ni NP catalytic activity due to the etching of the 3.2 nm Ni NPs giving Ni(Ⅱ)ions and the subsequent reduction of Ni(Ⅱ)that led to the formation of 1.6 nm Ni NPs on the SiO_(2)*** kinetics of the hydrolysis of AB catalyzed by Ni/SiO_(2)was shown to be dependent on catalyst and substrate concentration as well as *** Ni/SiO_(2)catalyst has a turnover frequency(TOF)of 13.2 mol H_(2)⋅(mol Ni)^(–1)⋅min^(–1)—the best ever reported for the hydrolysis of AB using a nickel catalyst,an activation energy of 34 kJ/mol±2 kJ/mol and a total turnover number of 15,400 in the hydrolysis of *** is a promising candidate to replace noble metals for catalyzing AB hydrolysis and for hydrogen generation under ambient conditions.

关键词： Nickel nanoparticles supported catalyst hydrogen storage hydrolysis of ammonia-borane

Design of a large-scale model for wind tunnel test of a multiadaptive flap concept

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Chinese Journal of Aeronautics 2024年第2期37卷 58-80页

作者： Mürüvvet Sinem SICIM DEMIRCI Rosario PECORA metin Orhan KAYA Aeronautical Engineering Department Istanbul Technical UniversityIstanbulTurkey Industrial Engineering Department University of Naples Federico IINapoliItaly

The design and application of morphing systems are ongoing issues compelling the aviation *** Clean Sky-program represents the most significant aeronautical research ever launched in Europe on advanced technologies for greening next-generation *** primary purpose of the program is to develop new concepts aimed at decreasing the effects of aviation on the environment,increasing reliability,and promoting eco-friendly *** ambitions are pursued through research on enabling technologies fostering noise and gas emissions reduction,mainly by improving aircraft aerodynamic *** the Clean Sky framework,a multimodal morphing flap device was designed based on tight industrial requirements and tailored for large civil aircraft *** flap is deployed in one unique setting,and its cross section is morphed differently in take-off and landing to get the necessary extra lift for the specific flight ***,during the cruise,the tip of the flap is deflected for load control and induced drag *** manufacturing the first flap prototype,a high-speed(Ma=0.3),large-scale test campaign(geometric scale factor 1:3)was deemed necessary to validate the performance improvements brought by this novel system at the aircraft *** the other hand,the geometrical scaling of the flap prototype was considered impracticable due to the unscalability of the embedded mechanisms and actuators for shape ***,a new architecture was conceived for the flap model to comply with the scaled dimensions requirements,withstand the relevant loads expected during the wind tunnel tests and emulate the shape transition capabilities of the true-scale *** strategies were developed to effectively morph the model during wind tunnel tests while ensuring the robustness of each morphed configuration and maintaining adequate stiffness levels to prevent undesirable deviations from the intended aerodynamic ***,

关键词： Morphing structures Smart aircraft Morphing flap Adaptive systems Finger-like ribs Wind tunnel tests Large-scale morphing archi-tectures Variable camber airfoil

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智能材料助力实现微纳尺度操控

Science Bulletin 2024年第6期69卷 718-721页

作者：张明超 metin Sitti Physical Intelligence Department Max Planck Institute for Intelligent SystemsStuttgart 70569Germany Institute for Biomedical Engineering ETH ZürichZürich 8092Switzerland School of Medicine and College of Engineering KoçUniversityIstanbul 34450Turkey

At the macroscopic world,we often take the manipulation of objects in our environment for ***,at the micro/nanoscale,the precise and controlled alteration,handling,or actuation(i.e.,manipulation)of materials and structures are highly challenging and different due to the scaling effects and increased complexity of dominant interaction forces at these length scales[1],requiring new materials and methods.

关键词：智能材料微纳尺度 precise

Tool life modeling for evaluating the effects of cutting speed and reinforcements on the machining of particle reinforced metal matrix composites

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 353-362页

作者： metin Kk Vocational College Education Kahramanmaras Sütü Imam University

The wear of cutting tools in the machining of 2024Al alloy composites reinforced with Al2O3 particles using varying sizes and volume fractions of particles up to 23.3vol% was investigated by a turning process using coated carbide tools K10 and TP30 at different cut- ting speeds. Machining tests were performed with a plan of experiments based on the Taguchi method. The tool life model was developed in terms of cutting speed, size, and volume fraction of particles by multiple linear regressions. The analysis of variance （ANOVA） was also employed to carry out the effects of these parameters on the cutting tool life. The test results show that the tool life decreases with the increase of cutting speed for both cutting tools K10 and TP30, and the tool life of the K10 tool is significantly longer than that of the TP30 tool. For the tool life, cutting speed is found to be the most effective factor followed by particle content and particle size, respectively. The predicted tool life of cutting tools is found to be in very good agreement with the experimentally observed ones.

关键词： metal matrix composites analysis of variance mathematical modeling tool life

Aerodynamics of non-slender delta and reverse delta wings:Wing thickness,anhedral angle and cropping ratio

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Chinese Journal of Aeronautics 2023年第4期36卷 79-91页

作者： Göktug KOCAK Mehmet metin YAVUZ Turkish Aerospace Industries Inc.Aerodynamics Chief Engineer at TF-XProjectAnkara 06980Turkey Mechanical Engineering Department Middle East Technical UniversityAnkara 06800Turkey

The effects of thickness-to-chord(t=c)ratio,anhedral angle(d),and cropping ratio from trailing-edge(Cr%)on the aerodynamics of non-slender reverse delta wings in comparison to non-slender delta wings with sweep angle of 45°were characterized in a low-speed wind tunnel using force and pressure *** measurements were conducted for total of 8 different delta and reverse delta *** different t/c ratios of 5.9%and 1.1%,and two different anhedral angles ofd=15°and 30°for non-cropped and cropped at Cr=30%conditions were *** results indicate that the reverse delta wings generate higher lift-to-drag ratio and have better longitudinal static stability characteristics compared to the delta *** wing thickness has favorable effect on longitudinal static stability for the reverse delta wing whereas longitudinal static stability is not influenced by wing thickness for the delta *** reverse delta wings,the anhe-draled wing without cropping has adverse effect on aerodynamic performance and decreases the lift-to-drag *** in anhedraled wing causes significant improvement in lift-to-drag ratio,shift in aerodynamic and pressure centers towards the trailing-edge,and enhancement in longitudi-nal static stability.

关键词： Aerodynamic coefficients Anhedral Cropping Leading-edge vortex Longitudinal static stability Non-slender delta wing Non-slender reverse delta wing Stall Three-dimensional surface separation

Effect of air annealing on the optical electrical and structural properties of In_2S_3 films

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Science China(Technological Sciences) 2008年第5期51卷 487-493页

作者： metin BEDIR Mustafa ZTAS Engineering Faculty Department of Engineering Physics Gaziantep University

The effect of the annealing temperature Ta on the optical, electrical and structural properties of the In2S3 films obtained by the spray pyrolysis method at 350℃ substrate temperature was studied. All the In2S3 films annealed in the range from 100 to 400℃ are polycrystalline with (220) preferential orientation. The resistivity decreases as Ta increases until it reaches a value of 25 Ohm-cm for Ta=400℃. The grain size also increases when Ta increases as observed in data calculated from X-ray measurements. XRD data indicates that samples show microstructural perfection improvement as a function of annealing temperature.

关键词： In2S3 spray pyrolysis annealing structural properties

Enhanced catalytic activity of monodispersed AgPd alloy nanoparticles assembled on mesoporous graphitic carbon nitride for the hydrolytic dehydrogenation of ammonia borane under sunlight

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Nano Research 2017年第5期10卷 1627-1640页

作者： Hamza Kahri Melike Sevim Onder metin Department of Chemistry Faculty of Science Ataturk University 25240 Erzurum Turkey Laboratoire de Synthese Organique Asymetrique et Catalyse Homogene (UR11ES56) Faculte des Sciences de Monastir Universite de Monastir Bd. de I'Environnement 5019 Monastir Tunisia East Anatolian High Technology Research and Application Center (DAYTAM) Ataturk University 25240 Erzurum Turkey

We address the composition-controlled synthesis of monodispersed AgPd alloy nanoparticles （NPs）, their assembly for the first time on mesoporous graphitic carbon nitride （mpg-C3N4）, and the unprecedented catalysis of mpg-CgN4@AgPd in the hydrolytic dehydrogenation of ammonia borane （AB） at room temperature. Monodispersed AgPd alloy NPs were synthesized using a high-temperature organic-phase surfactant-assisted protocol comprising the co-reduction of silver（I） acetate and palladium（II） acetylacetonate in the presence of oleylamine, oleic acid, and 1-0ctadecene. This protocol allowed the synthesis of four different compositions of AgPd alloy NPs. The AgPd alloy NPs were then assembled on mpg-C3N4, reduced graphene oxide, and Ketjenblack using a liquid-phase self-assembly method. Among the three supports tested, the mpg-CBN4@AgPd catalysts provided the best activity because of the Mott-Schottky effect, which was driven by the favorable work function difference between mpg-CBN4 and the metal NPs. Moreover, the activity of the mpg-CBN4@AgPd catalyst was further enhanced by an acetic acid treatment （AAt）, and a record initial turnover frequency of 94.1 mOl（hydrogen）＇mOl（catalyst）-l-min-1 was obtained. Furthermore, the mpg-CBN4@Ag42Pdss-AAt catalyst also showed moderate durability for the hydrolysis of AB. This study also includes a wealth of kinetic data for the mpg-CBN4@AgPd-catalyzed hydrolysis of AB.

关键词： silver palladium alloy nanoparticles graphitic carbon nitride ammonia borane dehydrogenation

ON THE m^(th) ORDER DIFFERENCE SEQUENCE SPACE OF GENERALIZED WEIGHTED MEAN AND COMPACT OPERATORS

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Acta Mathematica Scientia 2013年第3期33卷 797-813页

作者： metin BASARIR Emrah Evren KARA Department of Mathematics Sakarya University Department of Mathematics Bilecik Seyh Edebali University

In this article, using generalized weighted mean and difference matrix of order m, we introduce the paranormed sequence space l（u, v, p; △（m））, which consist of the sequences whose generalized weighted △（m）-difference means are in the linear space l（p） defined by ***. Also, we determine the basis of this space and compute its α-, β- and γ-duals. Further, we give the characterization of the classes of matrix mappings from l（u, v, p, △（m）） to l∞, c, and co. Finally, we apply the Hausdorff measure of noncompacness to characterize some classes of compact operators given by matrices on the space lp（U, v, △（m））（1 ≤ p 〈 ∞）.

关键词： Paranormed sequence spaces difference sequence spaces weighted mean α-,β, γ-duals, matrix mappings Hausdorff measure of noncompactness compactoperators

A Modified Gravity Theory: Null Aether

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Communications in Theoretical Physics 2019年第3期71卷 312-326页

作者： metin Gürses ?etin ?entürk Department of Mathematics Faculty of Sciences Bilkent University Department of Physics Faculty of Sciences Bilkent University Department of Aeronautical Engineering University of Turkish Aeronautical Association

General quantum gravity arguments predict that Lorentz symmetry might not hold exactly in nature. This has motivated much interest in Lorentz breaking gravity theories recently. Among such models are vector-tensor theories with preferred direction established at every point of spacetime by a fixed-norm vector field. The dynamical vector field defined in this way is referred to as the "aether". In this paper, we put forward the idea of a null aether field and introduce, for the first time, the Null Aether Theory(NAT) — a vector-tensor theory. We first study the Newtonian limit of this theory and then construct exact spherically symmetric black hole solutions in the theory in four dimensions, which contain Vaidya-type non-static solutions and static Schwarzschild-(A)dS type solutions, Reissner-Nordstr?m-(A)dS type solutions and solutions of conformal gravity as special cases. Afterwards, we study the cosmological solutions in NAT:We find some exact solutions with perfect fluid distribution for spatially flat FLRW metric and null aether propagating along the x direction. We observe that there are solutions in which the universe has big-bang singularity and null field diminishes asymptotically. We also study exact gravitational wave solutions — AdS-plane waves and pp-waves — in this theory in any dimension D ≥ 3. Assuming the Kerr-Schild-Kundt class of metrics for such solutions, we show that the full field equations of the theory are reduced to two, in general coupled, differential equations when the background metric assumes the maximally symmetric form. The main conclusion of these computations is that the spin-0 aether field acquires a "mass" determined by the cosmological constant of the background spacetime and the Lagrange multiplier given in the theory.

关键词： Aether theory Newtonian limit black holes cosmological solutions Kerr-Schild-Kundt class of metrics Ads-plane waves pp-waves

Stress analysis of functionally graded rotating discs: analytical and numerical solutions

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Acta Mechanica Sinica 2011年第6期27卷 950-955页

作者： Hasan Callioglu Numan Behll Bektas metin Sayer Department of Mechanical Engineering Pamukkale University

This study deals with stress analysis of annular rotating discs made of functionally graded materials（FGMs）.Elasticity modulus and density of the discs are assumed to vary radially according to a power law function,but the material is of constant Poisson＇s ratio.A gradient parameter n is chosen between 0 and *** n = 0,the disc becomes a homogeneous isotropic *** and radial stress distributions and displacements on the disc are investigated for various gradient parameters n by means of the diverse elasticity modulus and density by using analytical and numerical ***,a homogenous tangential stress distribution and the lowest radial stresses along the radius of a rotating disc are approximately obtained for the gradient parameter n = 1.0 compared with the homogeneous,isotropic case n = *** means that a disc made of FGMs has the capability of higher angular rotations compared with the homogeneous isotropic disc.

关键词： Functional graded materials Stress analysis Analytical analysis Finite element analysis (FEA)