In this paper, the ADINA finite element software was used for numerical investigation of laminar and non-Newtonian flow through a blood artery with consecutive stenosis. For modeling the non-Newtonian behavior of blood, six models were used, namely, Carreau, Carreau-Yasuda, modified Casson, Power law, generalized power law, and Walburn-Schneck. The results show that for all non-Newtonian models as well as the Newtonian model, the velocity of blood flow in the second stenosis is greater than the first stenosis. Also, up to 4D back of second stenosis, a reverse flow area is formed that causes the spread of disease and the formation of new plaque. As a general conclusion, it can be stated that due to the smaller values obtained from the power law and Walburn-Schneck models, as compared with the other models, for fluid velocity and wall shear stress, these two models must be applied with caution. Manuscript profile

Piezoelectric Microcantilevers (MCs) are efficient tools in switches of MEMS, AFMs and nano-resonators. Creating maximum vibrating motion with minimum excitation voltage is important in reducing power consumption and noise in this type of MCs. Therefore, investigating the factors affecting the excitability of MCs, as well as the degree of the effect of each of these factors, have an important role in the design and optimal selection of this type of resonators. Therefore, the aim of this paper was to investigate the excitability of this type of MCs. Modeling is conducted according to Hamilton principle and Euler-Bernoulli theory. Equation of motion was solved using Galerkin method with respect to geometrical discontinuities. Finally, eFAST sensitivity analysis was performed on excitability of MCs using statistical methods. Sensitivity analysis results show that the length and thickness of the piezoelectric layer are the most influential parameters on the excitability of MCs. At L1/L=0.74, the excitability reaches its maximum value. Manuscript profile

The growing development of nanobiotechnology and its applicability resulted in a wider range of use of Microcantilevers (MCs) in liquid. Considering the applications of piezoelectric MCs in the microelectromechanical systems and Atomic Force Microscope (AFM), as well as the high performance of these beams, this article investigates the vibrating behavior of multilayer piezoelectric MCs with geometric discontinuity in liquid environment. Due to the extreme complexity of hydrodynamic forces introduced to MCs, this force may reduce their accuracy. As a result, the MC was considered to be semi-submerged in the liquid medium to reduce the effect of hydrodynamic force. In addition, to reduce the effect of hydrodynamic force on vibrating behavior of the MC, sensitivity analysis was performed on its geometric dimensions to obtain the optimal dimensions, aiming at minimizing the effect of this force. The differential equation of motion was derived using the Euler–Bernoulli theory and the Lagrange method. The hydrodynamic force was exerted on the MC through the sphere string model. The Simulation results indicated that due to reducing resonance frequency variations in the third vibrating mode, the effect of hydrodynamic force on vibrating motion is minimized in this mode and considered as the optimal vibrating mode among the first three modes. The sensitivity analysis results showed that the MC length and piezoelectric layer were geometric parameters with the greatest effect on frequency sensitivity of MC, which should be considered in semi-submerged piezoelectric MC design. Manuscript profile