Background: Since three decade ago, the application of the concept of finite element analysis (EEA) have received a keen interest among dental investigators. In practice the FEA provides detailed STRESS information regarding to a non-homogenious body such as craniofocal skeletal growth, tooth post ceramo-metal crowns and etc. The aim of this study was the determination of the influence of STRESS distribution at the cement interface of metal ceramic restoration-dentin. Materials and Methods: An idealized metal-ceramic crown model was developed. The model was divided into very small segments. Various loading conditions was applied to the model. A super sap software was used for analyzing the STRESS distribution. Results & Conclusion: The results of this study suggest that the higher SHEAR STRESS was developed in the cervical region by two dimensional methods.

The ow of uids including micron particles in micro channels and manufacturing micro uidics tools have been one of the important topics in last decades and are utilized in di erent industries. The research procedure is experimental in this work. The experimental tests are carried out on the ow in a convergent-divergent microchannel having 200  m height. The utilized experimental method in this research is particle tracking based on the xerography technique, observation, record and data processing. The results showed that the velocity of the particles in Y-direction has a great e ect on their motion in the convergent-divergent channel. Study of the particles' sedimentation in di erent Reynolds showed that it can be eliminated the destructive e ect of channel obstruction using convergent-divergent channel which is originated from increasing sedimentation in low Reynolds. The SHEAR STRESS and velocity gradient are two main factors of the particles' velocity in the convergent-divergent channel. The results showed that the SHEAR STRESS has an excessive impact on the particles' velocity than the velocity gradient. Moreover, besides the upper and bottom walls, side walls a ect the particles' velocity.

The velocity field and the adequate SHEAR STRESS, corresponding to the flow of a generalized second grade FLUID in an annular region, due to a quadratic time-dependent SHEAR STRESS, are determined by means of the Laplace and the finite Hankel transforms. The solutions that have been obtained satisfy both the governing equations and all imposed initial and boundary conditions. For b®1 or b®1 and a1®0, the corresponding solutions for a second grade FLUID, respectively, for the Newtonian FLUID, performing the same motion, are obtained from general solutions. Finally, the influence of the material and fractional parameters on the SHEAR STRESS as well as a comparison between models is drawn by graphical illustrations.