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Chinese Journal of Electrical Engineering 2023年第4期9卷 107-121页

作者： ehsan akbari Milad Samady Shadlu Department of Electrical Engineering Mazandaran University of Science and TechnologyBabol ***Iran Department of Electrical Engineering Islamic Azad UniversityBojnourd BranchBojnourd ***Iran

A wind energy conversion system(WECS)based on a permanent magnet synchronous generator(PMSG)is an effective solution for renewable energy generation in modern power *** main advantages of PMSG include high performance at high and low speeds,minimal control effort owing to lower rotor inertia,self-excitation,high reliability,and simplicity of structure compared with induction ***,the intermittent nature of wind energy implies that maximum efficiency is not obtained from this ***,maximum power point tracking(MPPT)in wind turbine systems has been proposed to address this *** MPPT strategies suffer from severe output power fluctuations,low efficiency,and significant ripples in turbine rotation *** paper presents a novel MPPT control strategy based on fuzzy logic control(FLC)and model predictive control(MPC)to extract the maximum power from a PMSG-WECS and control the machine-side and grid-side *** simulation results obtained from Matlab/Simulink confirm the superiority of the control model in eliminating the output power fluctuations of the wind generators and accurately tracking the maximum power point.A comparative study between conventional MPPT and control methods is also conducted.

关键词： Maximum power point tracking(MPPT) wind energy conversion system(WECS) permanent magnet synchronous generator(PMSG) fuzzy logic control(FLC) model predictive control(MPC)

Effects of strain-induced melt activation treatment on the microstructure and properties of Zn sacrificial anodes

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International Journal of Minerals,Metallurgy and Materials 2021年第10期28卷 1693-1704页

作者： Behrooz Shayegh Boroujeny Payam Raiesi Goojani ehsan akbari Department of Engineering Shahrekord UniversityShahrekordIran

The microstructural properties and electrochemical performance of zinc(Zn)sacrificial anodes during strain-induced melt activation(SIMA)were investigated in this *** samples were subjected to a compressive ratio of 20%-50% at various temperatures(425-435℃)and durations(5-30 min).Short-term electrochemical tests(anode tests)based on DNV-RP-B401 and potentiodynamic polarization tests were performed in 3.5wt%NaCl solution to evaluate the electrochemical efficiency and corrosion behavior of the samples,*** electrochemical test results for the optimum sample confirmed that the corrosion current density declined by 90% and the anode efficiency slightly decreased relative to that of the raw ***-dispersive X-ray spectroscopy,scanning electron microscopy,metallographic images,and microhardness profiles showed the accumulation of alloying elements on the boundary and the conversion of uniform corrosion into localized corrosion,hence the decrease of the Zn sacrificial anode’s efficiency after the SIMA process.

关键词： strain-induced melt activation process zinc sacrificial anode corrosion resistance anode test

Engineering Nano/Microscale Chiral Self‑Assembly in 3D Printed Constructs

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Nano-Micro Letters 2024年第3期16卷 313-332页

作者： Mohsen Esmaeili ehsan akbari Kyle George Gelareh Rezvan Nader Taheri‑Qazvini Monirosadat Sadati Department of Chemical Engineering University of South CarolinaColumbiaSC 29208USA TA Instruments Waters LLCNew CastleDE 19720USA Biomedical Engineering Program University of South CarolinaColumbiaSC 29208USA

Helical hierarchy found in biomolecules like cellulose,chitin,and collagen underpins the remarkable mechanical strength and vibrant colors observed in living *** study advances the integration of helical/chiral assembly and 3D printing technology,providing precise spatial control over chiral nano/microstructures of rod-shaped colloidal nanoparticles in intricate *** designed reactive chiral inks based on cellulose nanocrystal(CNC)suspensions and acrylamide monomers,enabling the chiral assembly at nano/microscale,beyond the resolution seen in printed *** employed a range of complementary techniques including Orthogonal Superposition rheometry and in situ rheo-optic measurements under steady shear rate *** techniques help us to understand the nature of the nonlinear flow behavior of the chiral inks,and directly probe the flow-induced microstructural dynamics and phase transitions at constant shear rates,as well as their post-flow ***,we analyzed the photo-curing process to identify key parameters affecting gelation kinetics and structural integrity of the printed object within the supporting *** insights into the interplay between the chiral inks self-assembly dynamics,3D printing flow kinematics and photopolymerization kinetics provide a roadmap to direct the out-of-equilibrium arrangement of CNC particles in the 3D printed filaments,ranging from uniform nematic to 3D concentric chiral structures with controlled pitch length,as well as random orientation of chiral *** biomimetic approach can pave the way for the creation of materials with superior mechanical properties or programable photonic responses that arise from 3D nano/microstructure and can be translated into larger scale 3D printed designs.

关键词： Directed chiral self-assembly Cellulose nanocrystals Bioinspired nanocomposite 3D printing Rheology

Effect of copper slag recovery on hydrometallurgical cut-off grades considering environmental aspects

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Journal of Central South University 2016年第4期23卷 798-807页

作者： AFSHIN akbari ESMAEIL RAHIMI Department of Mining Engineering Islamic Azad University-Central Tehran Branch Department of Mining Engineering Islamic Azad University-South Tehran Branch

Determining the hydrometallurgical cut-off grades specifies the destination of low grade materials and this is subjected to more benefits in mining. Copper production rate is considered as one of the fundamental issues in hydrometallurgical cut-off grades determination. Slags are remarked as one of the main sources of copper. It is not only regarded as a waste but also identified as another resource extracting base metals. Slags are characterized by copper high grade. Thus, slag copper recovery can be led to different cut-off grades and net present value(NPV). The current research scrutinizes the effect of slag recovery by both flotation and hydrometallurgical methods on the hydrometallurgical cut-off grades. For this purpose, the optimum cut-off grade algorithms of hydrometallurgical methods are developed by considering associated environmental parameters, incomes and also the costs. Then, their optimum amounts are calculated with NPV maximization as an objective function. The results indicate that considering slag copper recovery in the hydrometallurgical cut-off grade algorithms reduces the environmental costs caused by slag dumping and leads to more NPV by 9%.

关键词： hydrometallurgy cut-off grades low grade materials waste floatation slag copper recovery environmental parameters slag dumping NPV maximization

Application of diffusive transport model for better insight into retardation mechanisms involved in ion-imprinted membrane transport

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Chinese Journal of Chemical Engineering 2016年第9期24卷 1161-1165页

作者： ehsan Salehi Department of Chemical Engineering Faculty of Engineering Arak University

Heavy metal removal from water is a great concern for environmentalists and engineers. Ion-imprinted membranes are among the state of the art technologies for selective adsorption of heavy metals from aqueous environment. Dialysis permeation of nickel ions through Ni(II)-imprinted membranes has been thermodynamically studied in our prior work. In current study, the diffusive transport model was developed and then applied for better insight into the retardation mechanisms involved in the ion-imprinted membrane transport. The Sips isotherm model was coupled with the transport model to obtain the governing equation. Chemisorption and physical interactions(bulk diffusion and pore-clogging) were the most probable retardation mechanisms according to the modeling results. Relative retardation factor(η) was also defined as; transport-rate controlled by chemical adsorption to that controlled by physical interactions. With the help of the retardation factor, it was understood that the membrane behavior gradually changes from chemisorption to facilitated transport during permeation time. Effect of important operating parameters such as time, temperature and concentration on transport behavior was also investigated. Results indicated that chemisorption rate is rather higher at lower concentrations, early permeation times and reduced temperatures. In addition, η tabulated greater values for Ni(II) compared to Co(II) due to the imprinting effect.

关键词： Ion-imprinted membrane Mathematical modeling Chemisorption Retardation mechanism

QUOTIENT SPACE OF LMC-COMPACTIFICATION AS A SPACE OF z-FILTERS

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Acta Mathematica Scientia 2012年第5期32卷 2010-2020页

作者： Mohammad akbari Tootkaboni Department of Mathematics Faculty of ScienceShahed University18151-159TehranIran

The left multiplicative continuous compactification is the universal semigroup compactification of a semitopological *** this paper an internal construction of a quotient space of the left multiplicative continuous co... 详细信息

关键词： LMC-compactification z-filters quotient space

Effects of modified graphene oxide(GO) nanofluid on wettability and IFT changes: Experimental study for EOR applications

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Petroleum Science 2022年第4期19卷 1779-1792页

作者： ehsan Jafarbeigi Farhad Salimi ehsan Kamari Mohsen Mansouri Department of Chemical Engineering Kermanshah BranchIslamic Azad UniversityKermanshahIran Department of Petroleum Engineering Research Institute of Petroleum IndustryTehranIran Department of Chemical Engineering llam UniversityllamIran

The application of nanoparticles(NPs) in enhanced oil recovery(EOR) offers a practical approach to resolving some surface-related problems encountered in contemporary technological processes. In this study, graphene oxide nanosheets(GONs) were synthesized by Hummer's method and, then, were subjected to surface modification by hexamethyldisilazane(HMDS) and diazonium sulfonic(DS) compounds. The new combination was known as GO-Su-HMDS. The potential stability of GO-Su-HMDS nanofluids(NFs) was investigated using the zeta(ζ) potential test. A comparative study of the effect of the synthesized NFs on wettability alteration of the reservoir rock was performed using interfacial tension(IFT) and contact angle experiments. According to the results of this study, the contact angle decreased from the initial value of 161.(oil wet) to 35.(water wet). In addition, IFT decreased from18.45 mN/m for deionized(DI) water to 8.8 mN/m for 500 ppm GO-Su-HMDS NF. Moreover, the results of flooding experiments showed that the NPs of a GO-Su-HMDS concentration of 400 and 500 ppm could increase the oil recovery by 20% and 19%, respectively. The experimental results showed that GO-SuHMDS NFs with a concentration of 500 ppm have the best efficiency in terms of altering the wettability of the rock from oil wet to water wet. Thus, it can be said that this nanofluid can reduce the contact angle and IFT and also increase the sweeping efficiency of oil.

关键词： Wettability alteration Graphene oxide Contact angle Interfacial tension Zeta potential

Discrete element modeling of inherently anisotropic granular assemblies with polygonal particles

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Particuology 2012年第5期10卷 542-552页

作者： ehsan Seyedi Hosseininia Civil Engineering Department Faculty of Engineering Ferdowsi University of MashhadMashhad Iran

In the present article, we study the effect of inherent anisotropy, i.e., initial bedding angle of particles and associated voids on macroscopic mechanical behavior of granular materials, by numerical simulation of several biaxial compression tests using the discrete element method （DEM）. Particle shape is considered to be irregular convex-polygonal. The effect of inherent anisotropy is investigated by following the evolution of mobilized shear strength and volume change during loading. As experimental tests have already shown, numerical simulations also indicate that initial anisotropic condition has a great influence on the strength and deformational behavior of granular assemblies. Comparison of simulations with tests using oval particles, shows that angularity influences both the mobilized shear strength and the volume change regime, which originates from the interlocking resistance between particles.

关键词： Inherent anisotropyGranular materialDiscrete element methodPolygonal particles

Data driven models for compressive strength prediction of concrete at high temperatures

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Frontiers of Structural and Civil Engineering 2020年第2期14卷 311-321页

作者： Mahmood akbari Vahid JAFARI DELIGANI Department of Civil Engineering Faculty of EngineeringUniversity of KashanKashan ***Iran

The use of data driven models has been shown to be useful for simulating complex engineering processes,when the only information available consists of the data of the *** this study,four data-driven models,namely multiple linear regression,artificial neural network,adaptive neural fuzzy inference system,and K nearest neighbor models based on collection of 207 laboratory tests,are investigated for compressive strength prediction of concrete at high *** addition for each model,two different sets of input variables are examined:a complete set and a parsimonious set of involved *** results obtained are compared with each other and also to the equations of NIST Technical Note standard and demonstrate the suitability of using the data driven models to predict the compressive strength at high *** addition,the results show employing the parsimonious set of input variables is sufficient for the data driven models to make satisfactory results.

关键词： data driven model compressive strength oncrete high temperature

Quantization and Event-Triggered Policy Design for Encrypted Networked Control

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 946-955页

作者： Yongxia Shi ehsan Nekouei the Department of Electrical Engineering City University of Hong KongHong KongChina

This paper proposes a novel event-driven encrypted control framework for linear networked control systems(NCSs),which relies on two modified uniform quantization policies,the Paillier cryptosystem,and an event-triggered *** to the fact that only integers can work in the Pailler cryptosystem,both the real-valued control gain and system state need to be first quantized before *** is dramatically different from the existing quantized control methods,where only the quantization of a single value,e.g.,the control input or the system state,is *** handle this issue,static and dynamic quantization policies are presented,which achieve the desired integer conversions and guarantee asymptotic convergence of the quantized system state to the ***,the quantized system state is encrypted and sent to the controller when the triggering condition,specified by a state-based event-triggered strategy,is *** doing so,not only the security and confidentiality of data transmitted over the communication network are protected,but also the ciphertext expansion phenomenon can be ***,by tactfully designing the quantization sensitivities and triggering error,the proposed event-driven encrypted control framework ensures the asymptotic stability of the overall closedloop ***,a simulation example of the secure motion control for an inverted pendulum cart system is presented to evaluate the effectiveness of the theoretical results.

关键词： Cyber-security encrypted control event-triggered control(ETC) networked control systems(NCSs) semi-homomorphic encryption