in the present study, vibration of cylindrical laminates with different layers and angles were studied. in order to actuate and polarize in radial direction, a piezoelectric layer was located at outer surface of composite shell. laminates were assumed long enough so that plane strain state analysis in 2d can be used properly. in order to satisfy the boundary conditions, variables in terms of fo...

the paper studies optimization of shell-and-tube heat exchangers using the particle swarm optimization technique. a total cost function is formulated based on initial and annual operating costs of the heat exchangers. six variables – shell inside diameter, tube diameter, baffle spacing, baffle cut, number of tube passes and tube layouts (triangular or square) – are considered as the design para...

In this work core-shell structure Fe3O4@SiO2@meso-SiO2 microsphere has been successfully prepared. An inorganic magnetic core has been coated with multi-shell structure, dense nonporous silica as an inner layer and mesoporous silica as an outer layer. The dense silica shell can enhance the stability and minimize the negative effect of acidic condi...

In this paper, a study on the vibration of thin cylindrical shells made of a functionally gradient material (FGM) composed of stainless steel and nickel is presented. The effects of the FGM configuration are taken into account by studying the frequencies of two FG cylindrical shells. Type I FG cylindrical shell has nickel on its inner surface and stainless steel on its outer surface and Type II...

We present a review of some of the recent developments in the study of the W 3 string. One of the interesting features of the theory is that the physical spectrum includes states with non-standard ghost structure, such as excitations of the ghost fields, both for discrete-momentum and continuous-momentum states.

The behavior of an exponentially graded hybrid cylindrical shell subjected to an axisymmetric thermo-electro-mechanical loading placed in a constant magnetic field is investigated. The hybrid shell is consisted of a functionally graded host layer  embedded with pyroelectric layers as sensor and/or actuator  that can be imperfectly bonded to the inner and the outer surfaces of a shell. The shell...