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Momeni-Khabisi, Hamed,Tahani, Masoud Techno-Press 2022 Advances in nano research Vol.12 No.4
In the present study, the nonlocal strain gradient theory is used to predict the size-dependent buckling and post-buckling behavior of geometrically imperfect nano-scale piezo-flexomagnetic plate strips in two modes of direct and converse flexomagnetic effects. The first-order shear deformation plate theory is used to analyze analytically nano-strips with simply supported boundary conditions. The nonlinear governing equations of equilibrium and associated boundary conditions are derived using the principle of minimum total potential energy with consideration of the von Kármán-type of geometric nonlinearity. A closed-form solution of governing differential equation is obtained, which is easily usable for engineers and designers. To validate the presented formulations, whenever possible, a comparison with the results found in the open literature is reported for buckling loads. A parametric study is presented to examine the effect of scaling parameters, plate slenderness ratio, temperature, the mid-plane initial rise, flexomagnetic coefficient, different temperature distributions, and magnetic potential, in case of the converse flexomagnetic effect, on buckling and post-buckling loads in detail.
A. Momeni,K. Dehghani 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.5
Hot deformation behavior of AISI 410 martensitic stainless steel was investigated by conducting hot compression tests at a temperature range of 900 °C to 1150 °C and a strain rate of 0.001-1s−1. The relation between flow stress and Zener-Hollomon (Z) parameter was successfully modeled via the hyperbolic sine function under a wide range of deformation conditions, and the values were determined for the apparent activation energy, Q, and the empirical material constants A and n. Power-law equations show that the values of the peak and steady-state stress are related to the dimensionless parameter Z/A. The results also show that the flow stress deviates from linear dependence on the Z/A parameter at ασ < 0.8 and ασ > 1.2. The deviations reflect the power and exponential equations, respectively, for low and high stress levels. The way the peak and steady-state strains vary with the Z parameter was studied and best models were developed. A model based on the Avrami equation was developed to estimate the kinetics of the dynamic recrystallization (DRX)for different deformation conditions. The results of the model show that the Avrami exponent decreases as Z rises. In addition, the Avrami constant of k bears no distinct relation with Z. The optical microscopy observations of prior austenite grains confirm that the DRX grain size has an adverse relation with the Z parameter. The best relation between the DRX grain size and the Z/A ratio is proposed on the basis of the grain size measurements.
Mohammad Ehsan Momeni Heravi 한국섬유공학회 2020 Fibers and polymers Vol.21 No.6
In this paper, silver nanoparticles (Ag-NPs) colloidal suspensions with different particle sizes of 5 to 40 nm wereprepared. Dynamic light scattering (DLS) technique showed that the average hydrodynamic diameters of Ag-NPs were muchlarger than the particle diameters obtained using transmission electron microscopy and UV-Vis spectroscopy. The as-preparedAg-NPs with different average hydrodynamic diameters were incorporated in cotton fabrics by the pad-dry-cure method. Thesilver content before and after washing cycles were determined by inductively coupled plasma spectrometry (ICP). Theantibacterial properties of the fabrics after 0, 5 and 10 laundering cycles against both the Gram-negative bacterium ofEscherichia coli (E. coli) and the Gram-positive bacterium of Staphylococcus aureus (S. aureus) were examined and a clearvolcano trend was observed between the bacterial reduction rate (BR) and the hydrodynamic diameter of Ag-NPs loaded onthe fibers. The cotton fabric treated by the Ag-NPs with the hydrodynamic diameter of 52 nm, exhibited the highestantibacterial activity (about 98 %) after 10 laundering cycles, while the other samples on either side of the volcano were lessactive. The cytotoxicity of the cotton fabrics treated with Ag-NPs was assayed on mouse embryonic fibroblast cells andevaluated by an MTT assay. The results showed that Ag-NPs were not toxic. Field emission scanning electron microscopy(FESEM) obtained from the cotton fabric before and after washing cycles demonstrated that the Ag-NPs had tight bonds withthe surface of cotton fabric.
n-ARY HYPERGROUPS ASSOCIATED WITH n-ARY RELATIONS
Anvariyeh, Seid Mohammad,Momeni, Somayyeh Korean Mathematical Society 2013 대한수학회보 Vol.50 No.2
The notion of $n$-ary algebraic hyperstructures is a generalization of ordinary algebraic hyperstructures. In this paper, we associate an n-ary hypergroupoid (H, $f$) with an ($n+1$)-ary relation ${\rho}_{n+1}$ defined on a non-empty set H. Then, we obtain some basic results in this respect. In particular, we investigate when it is an $n$-ary $H_v$-group, an $n$-ary hypergroup or a join $n$-ary space.
n-ary hypergroups associated with n-ary relations
Seid Mohammad Anvariyeh,Somayyeh Momeni 대한수학회 2013 대한수학회보 Vol.50 No.2
The notion of n-ary algebraic hyperstructures is a general- ization of ordinary algebraic hyperstructures. In this paper, we associate an n-ary hypergroupoid (H, f) with an (n+ 1)-ary relation ρn+1 defined on a non-empty set H. Then, we obtain some basic results in this re- spect. In particular, we investigate when it is an n-ary Hv-group, an n-ary hypergroup or a join n-ary space.
Abolghassem Zabihollah,Saman Momeni,Ali Selk Ghafari 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1
The dynamic behavior of nonuniform-thickness laminated composite beams, such as helicopter blades, wind turbine blades, and robotarms, is of high importance in the design and fabrication of such elements. Changing the thickness of laminated structures is a significantchallenge during fabrication because different tapering configurations may significantly alter the stiffness of the structures and thus thedynamic response of the structures. In this study, the effect of adding nanoparticles to resin on the stiffness and dynamic behavior ofnonuniform-thickness laminated composite beam elements was investigated. A set of experiments were conducted to examine the naturalfrequencies and damping coefficients of nonuniform-thickness laminated composite beams with different tapering configurations. Addingnanoparticles up to 3% increased the natural frequencies for all tapering configurations. Beyond 3% and up to 7% of nanoparticles,the natural frequency of the beam decreased. The addition of 10% of nanoparticles to resin sharply reduced the natural frequency of thebeam but significantly improved the damping coefficient for all the investigated taper models.
A Sliding Mode Observer Approach To Chaos Synchronization
Abdolkarim Daryabor,Hamid Reza Momeni 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
In this paper, synchronization of the chaotic systems based on sliding mode observer is presented. This observer has a simple structure that contains a sliding mode term which turns out to be robust against output noises as well as sustained disturbance. Only one of the states of the master that satisfies the observability matching condition is sent to the slave system via a public channel, which is a sliding mode observer designed to reconstruct all of the states of the master system. For verification and demonstration, this approach is applied to the unified chaotic systems. Simulation results are proposed to demonstrate the effectiveness of this method.
Influence of Graphene Oxide Nanoplates on Strengthening Mechanism of Al6061-GO Nanocomposites
Mahdi Hedayatian,Amir Momeni 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.1
In this paper, the effect of graphene oxide (GO) nanoplates on the strengthening mechanism of Al6061-GO nanocompositeshave been investigated. To make composite samples, GO nanosheets with various weight percents of 0.0, 0.2, 0.5, and 0.8%were added to the molten Al6061 through the stir casting method. Then the cast composite slabs were hot rolled. Tensiletest was used to study the mechanical properties of composite specimens. The experimental results showed that the nanoplatesof GO have strong strengthening effects along with increase in ductility in the fabricated composites. To model thestrengthening effect of GO in Al6061 matrix, the modified shear-lag and the modified Zhang-Chen strengthening mechanismshave been utilized. Comparisons between the model predictions and the experimental results revealed that both models cansatisfactorily predict the yield strength of fabricated nanocomposites.