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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

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

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

Plant-pollinator metanetworks in fragmented landscapes:a simulation study

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Ecological Processes 2023年第1期12卷 415-424页

作者： ehsan Rahimi Chuleui Jung Agricultural Science and Technology Institute Andong National UniversityAndong City 36729Republic of Korea Department of Plant Medicals Andong National UniversityAndong CityRepublic of Korea

Background The topology of the plant-pollinator network can be explained by the species’abundance and their random ***-pollinator networks can be studied in the context of a landscape,because each patch can accommodate a certain local *** populations of pollinators in the landscape can be connected through migration and then constitute a metanetwork that is known as a combination of spatial and ecological *** this regard,habitat fragmentation can affect the topology of plant-pollinator metanetworks through changes in the species abundance and limiting their ***,it is not clear what pattern(fragmented or aggregated)of the landscape structure can accommodate networks with a higher degree of *** we created simulated landscapes with different forest proportions scenarios(from 5%to 50%of the total landscape)and degrees of ***,for each landscape,we limited the proportion of pollinators to the forest *** assumed that plants and pollinators are randomly distributed around the landscape and interact *** used landscape metrics to measure different aspects of landscape structure and bipartite metrics for calculating the degree of specialization in plant-pollinator *** The statistical relationship between bipartite and landscape metrics showed that the relationship between the topology of plant-pollinator networks and the landscape structure is affected by the forest amount in the landscape and the degree of forest *** also found that according to the nestedness and H2(a measure of specialization)metrics,fragmented landscapes contain more general plant-pollinator *** Our findings suggest that fragmented landscapes,characterized by scattered forest patches,can promote higher levels of interaction between limited pollinators and diverse flowers,leading to more general plant-pollinator networks.

关键词： Plant–pollinator metanetwork Habitat fragmentation Simulated landscape Landscape metrics Bipartite metrics

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Improving the Surface Roughness of Dental Implant Fixture by Considering the Size,Angle and Spraying Pressure of Sandblast Particles

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Journal of Bionic Engineering 2024年第1期21卷 303-324页

作者： ehsan Anbarzadeh Bijan Mohammadi School of Mechanical Engineering Iran University of Science and TechnologyTehranIran

In this study,different conditions of sandblasting on dental implant fixtures were investigated to achieve the best sandblasting conditions.18 different sandblasting conditions(Using 152 implant fixture samples)were examined,including parameters such as particle size,particle blasting pressure,and particle blasting *** surface treatment of the samples was performed using the SLA+Anodizing *** testing was performed for each of the 18 different states,and the average surface roughness of each of these was compared with each ***,a bone layer was placed on the sample with the closest average surface roughness to the standard and the least amount of aluminum oxide on its surface among the 18 different states,to confirm the accuracy and quality of the desired surface roughness by examining the bone formation process and *** results showed that state No.4(sandblast particle size:75µm,spraying pressure of sandblast particles:4 bar,sandblast particle spraying angle:30 degrees),which was prepared using the SLA+Anodizing method and had a surface roughness of 1.989µm(The percentage of Al_(2)O_(3)on the surface=6%),had the best sandblasting conditions and showed 95%cell viability and accelerated the treatment and bone formation process for about a *** simulation results,using Abaqus software,indicated that the stress distribution on the surface of the implant fixture in contact with the bone surface has increased by approximately 4.3%for state *** will help prevent loosening of the dental implant fixture over time.

关键词： Dental implants Surface treatment Sandblast Surface roughness Osseointegration

Investigation of Poly(ether-b-amide)/Nanosilica Membranes for CO_2/CH_4 Separation

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Chinese Journal of Polymer Science 2014年第4期32卷 402-410页

作者： ehsan Seddigh Morteza Azizi ehsan Shirzaei Sani Davod Mohebbi-Kalhori Department of Chemical Engineering University of Sistan and Baluchestan

The results of molecular dynamics （MD） simulations on transport process of CO2 and CH4 gases in poly（ether-b- amide）（PEBAX）/nanosilica membranes are discussed. The diffusion coefficients for CH4 and CO2 gases at 6 cases with different amounts of nanosilica loading in the simulation boxes are presented. The results show that diffusion coefficients for CO2 gas in all cases are larger than those for the CH4 one. Moreover 10% nanosilica loading case shows maximum effects on diffusion coefficients and improves them by more than 68% and 157% for CO2 and CH4 gases, respectively. Additionally, the results of 3-D Cartesian trajectories and displacements curves are presented and the jumping attempt of CO2 is significantly more than that of CH4. Due to the rubbery state of PEBAX membranes in ambient temperature, the results confirm that channel lifetimes are very short and then back diffusion is not observed for this polymer.

关键词： Gas separation Polymeric membrane Molecular dynamics Diffusion coefficient.

A Test Approach for Look-Up Table Based FPGAs

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Journal of Computer Science & Technology 2006年第1期21卷 141-146页

作者： ehsan Atoofian Zainalabedin Navabi Department of Electrical and Computer Engineering University of Tehran 14399 Tehran Iran

This paper describes a test architecture for minimum number of test configurations in test of FPGA （Field Programmable Gate Array） LUTs （Look Up Tables）. The test architecture includes a TPG （Test Pattern Generator） that is tested while it is generating test data for LEs （Logic Elements） that form the CUT （Circuit Under Test）. This scheme eliminates the need for switching LEs between CUT, TPG and ORA （Output Response Analyzer） and having to perform many more reconfiguratioas of the FPGA. An external ORA locates faults of the FPGA under test. In addition to the LUTs, a scheme is presented for testing other parts of LEs. Compared with other methods, the presented scheme uses the least number of reconfigurations of an FPGA for its LUT testing.

关键词： FPGA testing BIST LUT testing memory testing TPG with LE

Catalytic process modeling and sensitivity analysis of alkylation of benzene with ethanol over MIL-101(Fe) and MIL-88(Fe)

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Frontiers of Chemical Science and Engineering 2020年第6期14卷 1100-1111页

作者： ehsan Rahmani Mohammad Rahmani Department of Chemical Engineering Amirkabir University of TechnologyTehran 158754413Iran

A solvothermal method was used to synthesize MIL-101(Fe)and MIL-88(Fe),which were used for alkylation of *** synthesized catalysts were characterized by X-ray diffraction,Fourier transform infrared spectroscopy,field emission scanning electron microscope,dynamic light scattering,and BET ***-organic frameworks(MOFs)were modeled to investigate the catalytic performance and existence of mass transfer *** effectiveness factors revealed absence of internal a nd external mass *** analysis revealed best operating conditions over MIL-101 at 120℃ and 5 bar and over MIL-88 at 142℃ and 9 bar.

关键词： MOFs alkylation ethylbenzene catalysts pellet model kinetic model sensitivity analysis