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Showing 3 results for Majidian


Volume 4, Issue 4 (12-2016)
Abstract

The phytoremediation capability in Pb removal from the contaminated soils by three native seedlings species (Acer cappadocicum, Fraxinus excelsior and Thuja orientalis) and one exotic species (Cupressus arizonica) were compared. The seedlings were grown in Pb contaminated soils at 0, 100, 200, 300, 400 and 500 mg kg-1 concentrations for 6 months (Mar 21 to Sept. 22, 2015), after which the biomass allocation and Pb accumulation in tissues of root, stem, and leaf were assessed. The results showed that the higher Pb levels (400 and 500 mg kg-1 soil) caused significant reduction in growth in all species, but this inhibition was less marked in the two conifer (T. orientalis and C. arizonica) compared to the two broad-leaf seedlings (A. cappadocicum and F. excelsior). Pb concentration in different tissues of seedlings increased with its increase in the soil. Further, Pb accumulation in the conifers was twice higher than that of the broad-leave species. Therefore, this study suggests that the two conifer species (P. orientalis and C. arizonica) can be used for phytoremediation, although further research is needed to make a final decision.
Mohammad Tahaye Abadi, Milad Majidian,
Volume 15, Issue 8 (10-2015)
Abstract

An experimental procedure is used to determine the transient response of an elastomeric isolator under the impact loading conditions and a numerical procedure is developed to evaluate the corresponding acceleration transmission ratio and shock response spectrum. In the experimental analysis the elastomeric isolator is connected to a resonance beam subjected to the shock loading of a pendulum striker and the shock level is measured using acceleration sensors mounted along three orthogonal directions in the basement and free end of isolator. The shock response spectrum diagram and the level of wave attenuation are determined based on the measured acceleration levels for a wide frequency range. Finite element model based on mode superposition approach is developed to analyze the impact response of elastomeric isolator using the mode shapes with frequency in range of impact excitation spectrum. Due to the importance of longitudinal response of isolators, the numerical model is employed to evaluate the longitudinal output acceleration time history of isolator. The number of elements, time step for motion equation integration and the number of mode shapes are studied and the optimized corresponding values are selected based on the convergence of the numerical results. The calculated results for wave attenuation level and shock response spectrum diagrams correlate well with the experimental measurements under two different impact loading conditions and the present model can be used to evaluate the performance of isolators depending on the level of impact loads and transmission acceleration and displacement ratios in the output of elastomeric isolators.
Ali Nazari, Keramt Malekzadeh Fard, Milad Majidian,
Volume 16, Issue 7 (9-2016)
Abstract

In this paper optimized the arrangement of the fiber metal laminate for cylindrical shells to achieve the maximum natural frequencies. In order to maximize the FML shell natural frequencies the sequence of the composite –metal layers and fiber orientation are changed frequently and for each case, the sample natural frequency is calculated. Finally FML shell with maximum natural frequencies is found. Hamilton‘s principle and energy method is used to define the equation of motion and First order shear deformation theory (FSDT) is utilized for vibration analysis in the shell’s equilibrium equation .In order to solve free vibration problem the double Fourier series is used to obtained the eigenvalue problem. For this purpose, through a MATLAB program linked to the finite element software of ABAQUS .different shells with various layer sequence and fiber orientation are created and studied from optimization aspect. This comprehensive program is able to analyses the FML shells with various arrangements of composite –metal layers, fiber orientation and boundary condition. The simply-simply and clamp-clamp boundary conditions are applied on edges. The applicable fiber orientations are 0,30,60,90 degrees.

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