Changes of up to 80°C has been reported for oral cavity temperature. This could well effecti on the nature of restorations for example failure of bonding of adhesive restorations. It is advocated that using opaque layer in porcelane to restorations could reduce this problem. This experimental study was designed to evaluate the effect mentioned using FINITElement analysis method.Results showed that cooling has a more destructive effect than warming process restorations with the presence of opaque having a FINITElement analysis effect on restorations.

In this paper, we propose a mathematical model for the human arterial tree. The FINITE ELEMENT method is used to solve the set of one-dimensional governing equations for blood flow. This model is able to predict the characteristics of blood flow such as the pressure wave propagation and the flow rate with reasonable accuracy. Comparison between three different models of blood; Newtonian, Power Law and Casson shows that the Casson model has almost similar results as the Newtonian, and the results from the Power Law model are close to the inviscid model. Comparison between the steady-state and the unsteady model demonstrates that the steady-state model can be used to predict the mean value of the unsteady variations within an acceptable accuracy range. The proposed model is also capable to predict the effects of different parameters on the blood pressure and the flow rate in arterial tree such as resistance and compliance of distal capillary beds.

Background and Aim: The movement of molars has been evaluated in many studies to correct Cl II malocclusion by non-compliance appliances but the results are controversial. The aim of this study was to compare the upper first and second molars' movement in cervical headgear (HG) and pendulum appliance (PEND) by FINITE ELEMENT method.Materials & Methods: For MODELING process, one of the best dry skulls was CT scanned (l mm slices). MODELING was done according to the mechanical properties of cortical and trabecular bone of maxilla and PDM and teeth and transferred to computer by scanner. ELEMENTing, meshing and loading was done. The magnitude of force for both appliances was 250 gr and line of force for HG was 20 degree above the occlusal plane action and for PEND was along the midlingual surface of upper first molar crown. Tooth movement analysis was performed by the software named Ansys 5.71.Results: The amount of dislocation of the 1st molar cusps tip (mesiobuccal, mesiopalatal, distobuccal, distopalatal) at presence of second molar in bucco-lingual dimension showed distal-in rotation in HG and mesial-in rotation for pendulum. In mesio-distal dimension, the four cusps of 1st molar moved distally in HG and palatal cusps moved more in PEND. In vertical dimension, 1st molar showed extrusion in HG and intrusion in PEND for distal cusps.Conclusion: The presence of second molar had impact on the quality of upper first molar in both appliances and it moved in a distal direction, extruded and buccal drifted in both of them. Therefore, with regard to the cooperation of the patients, pendulum appliance is recommended to correct Cl II malocclusion instead of cervical headgear.

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.

In the design of marine pipelines, like other thin-walled structures, structural stability plays major role. Generally, two kinds of instabilities, namely global buckling and local buckling (collapse) may occur in marine pipelines. However, for deep water pipelines in addition to occurrence of collapse, another concern is the potential occurrence of propagating of this collapse along the pipe due to high external pressure.In the present study, details of 2-D and 3-D FINITE ELEMENT MODELING for collapse propagation simulation are outlined. In order to verify the accuracy and validity of the FINITE ELEMENT MODELING, the numerical results, obtained from nonlinear FINITE ELEMENT analyses for severalpipe samples have been compared with the experimental results. These proposed 2-D and 3-D MODELING methods are easily applicable. Also, the comparison shows that the results of these methods have very close agreement with the experimental behavior. Using nominal geometric properties, finding minimum required imperfections to eliminate bifurcation points and using corrected Ramberg-Osgood material behavior for steel pipe are the main characteristics of the present 3-D method. The study shows that this method gives more appropriate results than the previous proposed method by Toscano et al. (2002).

In this paper, dynamic MODELING of flexible links manipulators is discussed. The MODELING approach is based on the Lagrange equations and FINITE ELEMENT discretization method. In order to obtain the closed form of dynamic equations for flexible links manipulators, symbolic calculation in MATLAB's symbolic mathematics toolbox is utilized, then the non-linear dynamic equations of a single-link manipulator have been obtained and compared with the results presented in other references. In this study, the nonlinear effects of centrifugal, Coriolis and gravity are Also considered which is rarely studied in other contributions. Then the equations of motion are solved by the Runge-Kutta method for different levels of excitation torque. The simulation results show that at low levels of excitation torque, the linear and non-linear models have the same results, while with the increase of the excitation level, the difference between the linear and non-linear models is considerable and the size of the elastic components in the non-linear model becomes smaller.

To analyze flows in channel expansions and contractions, two-dimensional, depth-averaged, unsteady flow equations are solved by using the two-step Taylor-Galerkin scheme. The 2-D, depth-averaged equations are written in a fully conservative form. The solution algorithm is based on an explicit time integration procedure which exploits the conservative properties of the governing equations. The unsteady flow model is used to obtain steady flow equations by treating the time variable as an iteration parameter and letting the solution converge to the steady state. The results of the mathematical model are compared with experimental data and other models. The capability of the model for handling mixed super- and sub-critical flows in a channel transition is demonstrated.

Summary Urmia tunnel is being constructed to convey water to the Naghadeh and Urmia agricultural plains. About 1800 m of excavations are located in the alluvial ground. In this paper, a part of Urmia tunnel that is located in the alluvial ground was modeled using the numerical MODELING FLAC3D and PLAXIS3D TUNNEL software packages. For this, first, the new Austrian tunneling method (NATM) was modeled. The NATM MODELING results showed high displacement and instability of the face of the tunnel. Then, the earth pressure balance (EPB) machine was modeled and the face pressure was calculated. The MODELING results showed suitable conformation between the two software packages. Moreover, a short-length part of the tunnel was excavated in the alluvial structure using the NATM, however, according to the MODELING results, the face of the tunnel was unstable, and thus, the excavation was stopped. The face pressure, in the tunnel boring machine(TBM) was also calculated. Introduction Urmia tunnel is a challenging project because of its especial ground and excavation conditions. The main focus of this research is on tunneling in hard conditions like high groundwater level, high depth of tunnel, too much overburden, etc. An example of tunneling in hard conditions is the Urmia tunnel that is studied in this paper. The main objective of this paper is to select a suitable method of excavation in the tunnel. Methodology and Approaches In this study, the NATM and its combination with soil improvement methods, and also, the EPB machine were modeled using the numerical MODELING FLAC3D and PLAXIS 3D TUNNEL software packages. A short-length part of the tunnel, which was excavated in the alluvial ground using the NATM, was considered in this study. Results and Conclusions The obtained MODELING results in this study showed high displacement of both face and crown and instability of the face in the NATM MODELING and combination of the NATM and soil improvement methods like jet-grouting and forepoling. Thus, the EPB machine was modeled and the face pressure was calculated.

Background and Aim: Considering the importance of the design of framework in the stress distribution and probability of creating initial cracks in connectors region, proper design of framework is considered as a requirement. For this purpose, in order to examine the stress distribution in two designs of straight and curved framework, comparison was made using FEM method.Materials and Methods: Research using a descriptive method of FEM was performed. A laboratory prototype was produced and was scanned in a digital form, using CMM equipment by the laboratory and a super spot from the geometry of the part was created. The super spot was transformed to a 3D solid model by utilizing Catia software. The above model was divided into a high number small ELEMENTs, using Meshing method, by Abaqus software to analyze the FINITE ELEMENTs. Afterwards, by Boundary Condition definition, the part was ready to be analyzed. The mechanical properties of Zirconia was entered into the software in the form of a table. Reviewing stress distribution in the bridge specially with the stress on connectors region was performed. Three vertical loading models for each part were applied in central and distal Fosa and analyzed separately.Results: In this study, the findings were described in the form of Von mises stress in Mpa scale. The stress in the Curved model was more than the Straight model. As a result, the stress distribution is more desirable.Conclusion: According to the results of this study, the straight model showed a more desirable stress distribution compared with the curved model. However, it should be noted that these results were obtained in F.E. environment.