This paper is investigated vibration of magneto-electro-elastic ((MEE)) composite conical shell on a nonlinear elastic foundation and under electric or magnetic potential while the influence of geometrical nonlinearity is taken into account. The conical shell is modeled based on the von Karman approach while the influences of shear deformation and rotary inertia are heeded. Coupled relations of (MEE) material are utilized to derive the vectors of stress, electric displacement as well as magnetic induction. Quasi-static Maxwell equations, Gauss' laws as well as thin shell assumptions are used to determine electric and magnetic fields. The nonlinear ordinary differential equation of the shell is derived through the Lagrange approach. Lindstedt-Poincare method and modal analysis are hired in order to obtain nonlinear vibration responses of the (MEE) composite conical shell. For validation intention, some results of the literature are compared with some results of this study. The effects of several parameters including nonlinear and linear constants of foundation, electric and magnetic potentials, thickness as well as length on the values of fundamental linear frequency, nonlinear parameter, and the curves of nonlinear frequency ratio versus amplitude parameter are investigated. The results show that the increase of the nonlinear constant of elastic foundation or thickness causes the increase of the nonlinear frequency ratio. On the other hand, the nonlinear frequency ratio gets smaller values with an increase in the linear constants of the elastic foundation or length.

In this study, the free vibration analysis of smart vibration control (SVC) systems based on Reddy – Levinson model and modified strain gradient theory is developed. This system consist of a micro beam at middle and two magneto-electro-elastic ((MEE)) composite micro beams at top and bottom which connected by enclosing elastic medium and simulated by Winkler and Pasternak foundation. The effects of the lower (MEE) composite micro beam in the absence of upper (MEE) composite micro beam and also the effect of both (MEE) composite micro beams together on the dimensionless natural frequency of the middle micro beam are evaluated. It is shown that the presence of both (MEE) composite micro beams together have less dimensionless natural frequency than presence of lower (MEE) composite micro beam alone. The results of this work can be useful to analysis, design and manufacture intelligent micro-systems to hamper resonance phenomenon or as a sensor to control the dynamic stability of micro structures.

Background and Objectives: Multi locus enzyme electrophoresis ((MEE)) has been proved to be a powerful technique in population genetic studies and molecular epidemiology of pathogenic micro-organisms. In this study (MEE) was used to determine the genetic relationships of M. kansasii strains cultured from patients at Pasteur Institute of Iran.Material and Methods: 21 isolates of M. kansasii (9 isolates from Iran and 12 isolates from other countries) were analyzed for 12 enzymes loci by (MEE). Isolates were grown on LJ slants and BACTEC 13A. The cells were sedimented by centrifugation and their lysates containing the enzymes were extracted by sonication. The horizontal starch gel electrophoresis was used for visualization of enzymes after staining the gels with substrate in solutions or agar overlay.Results: A considerable genetic diversity was found at different loci of M. kansasii suggesting the existence of different sub-species for this organism. It also showed the inaccuracy of some biochemical test for identification of some isolates with in this species.Conclusion: Iranian isolates of M. kansasii are genetically diverse. Separation of isolates at high genetic distances in this study suggests the possible existence of undetected isolates that could fill the gaps between the unrelated isolates.

Background and aim: Dental irreversible hydrocolloid (Alginate) is a major dental used world wide in many clinical procedures. The purpose of this study was to investingate the dimensional stability after prolonged storage of Alginate elastic Chromo. This study was carried out in 2008 in Azad Islamic university.Method and Material: This experimental study was carried out by using labratory metal master model that contained two dies.20 impression were taken for master model by Alginate elastic Chromo The four storage conditions were as follow: 0/5 hours, 24 hours , 48 hours, 120 hours, stone model were poured. Die's height, diameter and distance between dies were measured by profile projector and compared with labratory model by use ANOVA test.Results: There is no significant different between of four times casting. Height & distance dimensional change were less than 1/5% (Max distoration after 24 hours) but diameters were more than 1/5%.Conclusion: Alginate elastic Chromo was not dimensionally stable over a 5 day period ( 120 hours). However, no effect of the times on dimensional change.

In this paper, the stability of a functionally graded magneto-electro-elastic (FG-(MEE)) micro-beam under actuation of electrostatic pressure is studied. For this purpose Euler-Bernoulli beam theory and constitutive relations for magneto-electro-elastic ((MEE)) materials have been used. We have supposed that material properties vary exponentially along the thickness direction of the micro-beam. Governing motion equations of the micro-beam are derived by using of Hamilton’s principle. Maxwell’s equation and magneto-electric boundary conditions are used in order to determine and formulate magnetic and electric potentials distribution along the thickness direction of the micro-beam. By using of magneto-electric potential distribution, effective axial forces induced by external magneto-electric potential are formulated and then the governing motion equation of the micro-beam under electrostatic actuation is obtained. A Galerkin-based step by step linearization method (SSLM) has been used for static analysis. For dynamic analysis, the Galerkin reduced order model has been used. Static pull-in instability for 5 types of (MEE) micro-beam with different gradient indexes has been investigated. Furthermore, the effects of external magneto-electric potential on the static and dynamic stability of the micro-beam are discussed in detail.

The present work mainly studies the free vibration of circular magneto-electro-elastic ((MEE)) nano-plates based on Kirchhoff’s plate theory within the framework of nonlocal elasticity theory to account for the small scale effect. The (MEE) nano-plate studied here is considered to be fully clamped and subjected to the external magnetic and electric potentials. Using nonlocal constitutive relations of (MEE) materials, the governing equations are derived by applying Maxwell’s equation and Hamilton’s principle. By employing Galerkin method, the eigen matrix form of the governing equation is obtained. The effect of magneto-electric potential on instability of the system is investigated and consequently critical values of applied potentials are calculated. A detailed numerical study is conducted to study the influences of the small scale effect, thickness and radius of the nano-plate and piezoelectric volume fraction of the (MEE) material on the natural frequencies of nano-plate. Furthermore, the effects of the applied magnetic and electric potentials on the size-dependent natural frequencies are investigated numerically.

In this article, the time-dependent stress redistribution analysis of magneto-electro-elastic ((MEE)) thick-walled sphere subjected to mechanical, electrical, magnetic and uniform temperature gradient as well as moisture concentration gradient is presented. Combining constitutive equations of (MEE) with stress-strain relations as well as strain-displacement relations results in obtaining a differential equation in which there are the creep strains. At the first step, discounting creep strains in the mentioned equation, an analytical solution for the hygro-thermo-magneto-electro-elastic behavior is achieved at the initial state. After that, the creep stress rates can be achieved by keeping only the creep strains in the differential equation for the steady-state condition. The analysis is done by applying the Prandtl-Reuss equations as well as Norton’ s law in creep behavior modeling. Finally, the history of stresses, displacement as well as magnetic and potential field, at any time, is achieved using an iterative method. Results show that the increase in tensile hoop stress resulted from creep progress must be considered in design progress. In addition, the effect of hygrothermal loading is more extensive after creep evolution.

The Magneto-Electro-elastic ((MEE)) material exhibits pyroelectric and pyromagnetic effects under thermal environment. The effects of such pyroelectric and pyromagnetic behavior on vibration, buckling and deflection analysis of partially cracked thin (MEE) plate is presented and discussed in this paper. The aim of the study is to develop an analytical model for the vibration and geometrically linear thermal buckling analysis of cracked (MEE) plate based on the classical plate theory (CPT). The line spring model (LSM) is modified for the crack terms to accommodate the effect of electric and magnetic field rigidities, whereas the effect of thermal environment is accommodated in the form of thermal moment and in-plane forces. A classical relation for thermal buckling phenomenon of cracked (MEE) plate is also proposed. The governing equation for cracked (MEE) plate has also been solved to get central deflection which shows an important phenomenon of shift in primary resonance due to crack and temperature rise. The results evaluated for natural frequencies as affected by crack length, plate aspect ratio and critical buckling temperature are presented for first four modes of vibration. The obtained results reveal that the fundamental frequency of the cracked plate decreases with increase in temperature and crack length. Furthermore the variation of the critical buckling temperature with plate aspect ratio and crack length is also established for different modes of vibration.

In this article, the free vibration analysis of magneto-electro-elastic ((MEE)) Timoshenko micro beam model based on surface stress effect and modified strain gradient theory (MSGT) under moving nano-particle is presented. The governing equations of motion using Hamilton’s principle are derived and these equations are solved using differential quadrature method (DQM). The effects of dimensionless electric potential, dimensionless magnetic parameter, material length scale parameter, external electric voltage, external magnetic parameter, slenderness ratio, temperature change, surface stress effect, two parameters of elastic foundation on the dimensionless natural frequency are investigated. It is shown that the effect of electric potential and magnetic parameter simultaneously increases the dimensionless natural frequency. On the other hands, with considering two parameters, the stiffness of (MEE) Timoshenko micro beam model increases. It can be seen that the dimensionless natural frequency of micro structure increases by MSGT more than modified couple stress theory (MCST) and classical theory (CT). It is found that by increasing the mass of nanoparticle, the dimensionless natural frequency of system decreases. The results of this study can be employed to design and manufacture microdevices to prevent resonance phenomenon or as a sensor to control the dynamic stability of micro structures.

This paper introduces a novel harvester to store the electrical power, which comes from the power of external applied electrical voltage. In the last decade, most of the energy harvesters have been designed and analyzed in the form of cantilever beams. In the present article, the harvesters are analyzed as a cantilever beam with the Euler-Bernoulli beam assumptions. The beam of energy harvester consists of an active Magneto-electro-elastic ((MEE)) layer attached to the piezoelectric layer. Assuming that the connection of these layers is perfect, the uni-morph configuration is investigated. The magneto-electro-elastic governing coupled equations of the (MEE) energy harvester are derived for a harmonic external applied electrical voltage in the transversal direction based on Euler-Bernoulli theory, Gaussian law, and Faraday law. These equations are solved analytically to find out the amount of harvested power and voltage. The obtained results state that by adjusting the electromechanical parameters, up to 66% of the input power and 27% of the applied voltage can be harvested. Choosing the right geometric parameters can increase the harvested power and voltages connected to the electrodes and external coil by 120.31%, 49.05% and 60.98%, respectively. Finally, the results prove the usefulness and efficiency of the dual-usage (actuator-harvester) of the new energy harvester.