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Effects of copper content on microstructure and mechanical properties of open-cell steel foams

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 588-596页

作者： Hamid Sazegaran milad Hojati Department of Industrial Engineering Faculty of Engineering Quchan University of Technology Manufacturing Management of Mashhad Powder Metallurgy Company

The effects of copper content on the microstructural and mechanical properties of steel foams are investigated. Spherical urea granules, used as a water-leachable space holder, were coated with a mixture of iron, ultrafine carbon, and different amounts of copper powders. After the mixture was compacted and the space holder was removed by leaching, a sintering process was performed under an atmosphere of thermally dissociated ammonia. Microstructural evaluations of the cell walls were carried out using optical microscopy and scanning electron microscopy in conjunction with energy-dispersive X-ray spectroscopy. In addition, compression tests were conducted to investigate the mechanical properties of the manufactured steel foams. The results showed that the total porosity decreases from 77.2% to 71.9% with increasing copper content in the steel foams. In the foams' microstructure, copper islands are mostly distributed in pearlite and intergranular carbide phases are formed in the grain boundaries. When the copper content was increased from 0 to 4 wt%, the elastic modulus, plateau stress, fracture stress, and fracture strain of manufactured steel foams improved 4.5, 6, 6.4, and 2.5 times, respectively.

关键词： steel foam leachable space holder copper content liquid-phase sintering mechanical properties

Nonlinear vibration analysis of a circular micro-plate in two-sided NEMS/MEMS capacitive system by using harmonic balance method

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Acta Mechanica Sinica 2019年第1期35卷 129-143,I0004页

作者： milad Saadatmand Alireza Shooshtari Department of Electrical Engineering Technical University of DenmarkKgs.LyngbyDenmark Department of Mechanical Engineering Bu-Ali Sina UniversityHamedanIran

In this study, forced nonlinear vibration of a circular micro-plate under two-sided electrostatic, two-sided Casimir and external harmonic forces is investigated analytically. For this purpose, at first, von Karman plate theory including geometrical nonlinearity is used to obtain the deflection of the micro-plate. Galerkin decomposition method is then employed, and nonlinear ordinary differential equations (ODEs) of motion are determined. A harmonic balance method (HBM) is applied to equations and analytical relation for nonlineaT frequency response (F-R) curves are derived for two categories (including and neglecting Casimir force) separately. The analytical results for three cases:(1) semi-linear vibration;(2) weakly nonlinear vibration;(3) highly non linear vibration, are validated by comparing with the numerical solutio ns. After validation, the effects of the voltage and Casimir force on the natural frequency of two-sided capacitor system are investigated. It is shown that by assuming Casimir force in small gap distances, reduction of the natural frequency is considerable. The influences of the applied voltage, damping, micro-plate thickness and Casimir force on the frequency response curves have been presented too. The results of this study can be useful for modeling circular parallel-plates in nano /microelectromechanical transducers such as microphones and pressure sensors.

关键词： Nonlinear vibration Two-sided MEMS capacitor Circular plate Harmonic balance method

Robust Finite-time Synchronization of Non-identical Fractional-order Hyperchaotic Systems and Its Application in Secure Communication

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IEEE/CAA Journal of Automatica Sinica 2019年第1期6卷 228-235页

作者： Hadi Delavari milad Mohadeszadeh the Electrical Engineering Department Hamedan University of Technology

This paper proposes a novel adaptive sliding mode control(SMC) method for synchronization of non-identical fractional-order(FO) chaotic and hyper-chaotic systems. Under the existence of system uncertainties and external disturbances,finite-time synchronization between two FO chaotic and hyperchaotic systems is achieved by introducing a novel adaptive sliding mode controller(ASMC). Here in this paper, a fractional sliding surface is proposed. A stability criterion for FO nonlinear dynamic systems is introduced. Sufficient conditions to guarantee stable synchronization are given in the sense of the Lyapunov stability theorem. To tackle the uncertainties and external disturbances, appropriate adaptation laws are introduced. Particle swarm optimization(PSO) is used for estimating the controller parameters. Finally, finite-time synchronization of the FO chaotic and hyper-chaotic systems is applied to secure communication.

关键词： Adaptive sliding mode control (ASMC) chaos synchronization fractional order (FO) hyper-chaotic system Lyapunov theorem secure communication

Azole derivatives embedded in montmorillonite clay nanocarriers as corrosion inhibitors of mild steel

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International Journal of Minerals,Metallurgy and Materials 2019年第1期26卷 86-97页

作者： milad Edraki Davood Zaarei Polymer Department Technical Faculty South Tehran Branch Islamic Azad University

Azole derivatives such as 2-mercaptobenzothiazole(MBT) and 2-mercaptobenzimidazole(MBI) were introduced as corrosion inhibitors into the interlayer space of sodium montmorillonite clay(Na+-MMT). The corrosion protection behavior of mild steel in solutions containing MBT, MBI, MMT + MBT, MMT + MBI, Na^+-MMT, and NaCl(3.5 wt%) was evaluated using polarization and electrochemical impedance spectroscopy(EIS). Also, the release of penetrated species into the medium from the clay nanocarriers was evaluated using ultraviolet-visible(UV-Vis) spectroscopy. Small-angle X-ray scattering(SAXS) confirmed the insertion of MBT and MBI into the inner space of the clay layers and the interaction between two organic and inorganic phases. Scanning electron microscopy(SEM) was used to assess the morphology of the surface of the steel samples after the samples had been immersed for 24 h in the extraction solution. The corrosion protection in the solutions with clay nanocarriers containing MBT and MBI was better than that in solutions without MMT. The UV-Vis results showed that the release of MBI species from Na+-MMT nanocarriers in neutral pH was far lower than that of MBT species.

关键词： azole derivatives clay minerals release electrochemical impedance spectroscopy corrosion inhibition

Towards data-efficient mechanical design of bicontinuous composites usinggenerative AI

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Theoretical & Applied Mechanics Letters 2024年第1期14卷 57-64页

作者： milad Masrouri Zhao Qin Department of Civil and Environmental Engineering Syracuse UniversitySyracuseNY 13244USA Laboratory for Multiscale Material Modelling Syracuse UniversitySyracuseNY 13244USA The BioInspired Institute Syracuse UniversitySyracuseNY 13244USA

The distribution of material phases is crucial to determine the composite’s mechanical *** the full structure-mechanics relationship of highly ordered material distributions can be studied with finite number of cases,this relationship is difficult to be revealed for complex irregular distributions,preventing design of such material structures to meet certain mechanical *** noticeable developments of artificial intelligence(AI)algorithms in material design enables to detect the hidden structure-mechanics correlations which is essential for designing composite of complex *** is intriguing how these tools can assist composite ***,we focus on the rapid generation of bicontinuous composite structures together with the stress distribution in *** find that generative AI,enabled through fine-tuned Low Rank Adaptation models,can be trained with a few inputs to generate both synthetic composite structures and the corresponding von Mises stress *** results show that this technique is convenient in generating massive composites designs with useful mechanical information that dictate stiffness,fracture and robustness of the material with one model,and such has to be done by several different experimental or simulation *** research offers valuable insights for the improvement of composite design with the goal of expanding the design space and automatic screening of composite designs for improved mechanical functions.

关键词： Generative artificial intelligence Stable diffusion Composite design Phase field model Molecular dynamics simulation

Three-dimensional finite difference analysis of shallow sprayed concrete tunnels crossing a reverse fault or a normal fault: A parametric study

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Frontiers of Structural and Civil Engineering 2020年第4期14卷 998-1011页

作者： Masoud RANJBARNIA milad ZAHERI Daniel DIAS Department of Geotechnical Engineering Faculty of Civil EngineeringUniversity of TabrizTabrizIran Schoo of Automotive and Transportation Engineering Hefei University of TechnologyHefei 230009China Universite Grenoble Alpes Grenoble F-38000France

Urban tunnels crossing faults are always at the risk of severe *** this paper,the efects of a reverse and a normal fault movement on a transversely crossing shallow shotcreted tunnel are investigated by 3D finite difference *** verifying the accuracy of the numerical simulation predictions with the centrifuge physical model results,a parametric study is then *** is,theleffects of various parameters such as the sprayed concrete thickness,the geo-mechanical properties of soil,the tunnel depth,and the fault plane dip angle are studied on the displacements of the ground surface and the tunnel structure,and on the plastic strains of the soil mass around *** results of each case of reverse and normal faulting are independently discussed and then compared with each *** is obtained that deeper tunnels show greater displacements for both types of faulting.

关键词： urban tunnel sprayed concrete reverse fault normal fault finite difference analysis

High efficiency visible-light-driven Fe_2O_3-xS_x/S-doped g-C_3N_4 heterojunction photocatalysts: Direct Z-scheme mechanism

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Journal of Materials Science & Technology 2018年第9期34卷 1511-1525页

作者： milad Jourshabani Zahra Shariatinia Alireza Badiei Department of Chemistry Amirkabir University of Technology (Tehran Polytechnic) School of Chemistry College of Science University of Tehran Nanobiomedicine Center of Excellence Nanoscience and Nanotechnology Research Center University of Tehran

Several nanoporous Fe2 O3-xSx/S-doped g-C3 N4（CNS） Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe2O3-xSx particles on the surface of CNS. The characterization results show that S-doping in the g-C3 N4 backbone can greatly enhance the charge mobility and visible light harvesting capability. In addition, porous morphology of hybrid composite provides available open pores for guest molecules and also improves light absorbing property due to existence of multiple scattering effects. More importantly, the Fe2 O3-xSx nanoparticles formed intimate heterojunction with CNS and developed the efficient charge transfer by extending interfacial interactions occurred at the interfaces of both components. It has been found that the Fe2 O3-xSx/CNS composites have an enhanced photocatalytic activity under visible light irradiation compared with isolated Fe2 O3 and CNS components toward the photocatalytic degradation of methylene blue（MB）. The optimal loaded Fe2 O3-xSx value obtained is equal to 6.6 wt% that provided 82% MB photodegradation after 150 min with a reaction rate constant of 0.0092 min（-1） which was faster than those of the pure Fe2 O3（0.0016 min（-1））and CNS（0.0044 min（-1）） under the optimized operating variables acquired by the response surface methodology. The specific surface area and the pore volume of Fe2 O3（6.6）/CNS hybrid are 33.5 m2/g and0.195 cm3/g, which are nearly 3.8 and 7.5 times greater compared with those of the CNS, respectively. The TEM image of Fe2 O3（6.6）/CNS nanocomposite exhibits a nanoporous morphology with abundant uniform pore sizes of around 25 nm. Using the Mott-Schottky plot, the conduction and valence bands of the CNS are measured（at pH = 7） equal to-1.07 and 1.48 V versus normal hydrogen electrode（NHE）, *** tests prove that ·OH-and ·O2-radicals are major active species in the photocatalytic *** has been established that formation of the Z-scheme Fe2 O3（6.6）/CNS he

关键词： Visible light irradiation Nanophotocatalyst in situ S-doping Z-scheme heterojunction Response surface methodology(RSM)

Influence of glycine additive on corrosion and wear performance of electroplated trivalent chromium coating

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International Journal of Minerals,Metallurgy and Materials 2020年第4期27卷 544-554页

作者： Navid Mehdipour milad Rezaei Zeynab Mahidashti Department of Materials and Metallurgical Engineering Amirkabir University of Technology(Tehran Polytechnic)Hafez Ave.P.O.Box 15875-4413TehranIran

The aim of this study is to evaluate the effect of various molar ratios of glycine to chromium salt(Gly:Cr)and different current densities on the corrosion and wear behaviors of Cr(III)electroplated *** morphology and thickness of the coatings were investigated by scanning electron *** wear properties of the coatings were studied using pin on disk and hardness tests,while corrosion behavior of the coatings was identified using linear polarization,small amplitude cyclic voltammetry,and electrochemical impedance spectroscopy *** increasing the glycine concentration,a structure with low crack density was *** all molar ratios,maximum thickness and current efficiency was observed at a current density of 150 mA·cm?*** the electrochemical methods had a consistent result,and maximum corrosion resistance of approximately 16000Ω·cm2 was obtained in the case of Gly:Cr=3:1 and current density of 200 mA·cm?2.

关键词： electrodeposition trivalent chromium glycine corrosion resistance

Numerical Simulation of Dual-Phase-Lag Model and Inverse Fractional Single-Phase-Lag Problem for the Non-Fourier Heat Conduction in a Straight Fin

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Journal of Thermal Science 2020年第3期29卷 632-646页

作者： MOZAFARIFARD milad AZIMI Aziz MEHRZAD Salem Department of Mechanical Engineering Shahid Chamran University of AhvazAhvaz ***Iran

In recent years,many studies have been done on heat transfer in the fin under unsteady boundary conditions using Fourier and non-Fourier *** this paper,unsteady non-Fourier heat transfer in a straight fin having an internal heat source under periodic temperature at the base was investigated by solving numerically Dual-Phase-Lag and Fractional Single-Phase-Lag *** this way,the governing equations of these models were presented for heat conduction analysis in the fin,and their results of the temperature distribution were validated using the theoretical results of Single and Dual-Phase-Lag *** that,for the first time the order of fractional derivation and heat flux relaxation time of the fractional model were obtained for the straight fin problem under periodic temperature at the base using Levenberg-Marquardt parameter estimation *** solve the inverse fractional heat conduction problem,the numerical results of Dual-Phase-Lag model were used as the *** results obtained from Fractional Single-Phase-Lag model could predict the fin temperature distribution at unsteady boundary condition at the base as well as the Dual-Phase-Lag model could.

关键词： non-Fourier heat transfer fractional calculus inverse heat transfer Levenberg-Marquardt straight fin unsteady boundary condition