In this paper the effects of temperature on the radial breathing modes （RBMs） and radial wave propaga- tion in multiwall carbon nanotubes （MWCNTs） are inves- tigated using a continuum model of multiple elastic iso...In this paper the effects of temperature on the radial breathing modes （RBMs） and radial wave propaga- tion in multiwall carbon nanotubes （MWCNTs） are inves- tigated using a continuum model of multiple elastic isotropic shells. The van der Waals forces between tubes are simulated as a nonlinear function of interlayer spacing of MWCNTs. The governing equations are solved using a finite element method. A wide range of innermost radius-to-thickness ratio of MWCNTs is considered to enhance the investigation. The presented solution is verified by comparing the results with those reported in the literature. The effects of temperature on the van der Waals interaction coefficient between layers of MWCNTs are examined. It is found that the variation of the van der Waals interaction coefficient at high temperature is sensible. Subsequently, variations of RBM frequencies and radial wave propagation in MWCNTs with temperatures up to 1 600 K are illustrated. It is shown that the thick MWC- NTs are more sensible to temperature than the thin ones.展开更多
The piezoelectric properties of relaxor ferroelectric 0.65Pb（Mg1/3,Nb2/3）O3-0.35PTO3 ceramic prepared by a sol-gel combustion method have been investigated as function of sintering temperature. The results show that...The piezoelectric properties of relaxor ferroelectric 0.65Pb（Mg1/3,Nb2/3）O3-0.35PTO3 ceramic prepared by a sol-gel combustion method have been investigated as function of sintering temperature. The results show that its phase structure is near the morphoteropic phase boundary （MPB）, and outstanding electrical properties are obtained with this composition. The highest piezoelectric coefficients were observed for the samples sintered at temperature of 1200℃. In comparison with pure PMN （（1-x）Pb（Mg1/3Nb2/3）O3- （x）PbTiO3）, the substitution of 35% PT results in the decrease of sintered temperature and improved the relaxation behavior.展开更多
In this investigation,a semi-numerical method based on Bernstein polynomials for solving off-centered stagnation flow towards a rotating disc is introduced.This method expands the desired solutions in terms of a set o...In this investigation,a semi-numerical method based on Bernstein polynomials for solving off-centered stagnation flow towards a rotating disc is introduced.This method expands the desired solutions in terms of a set of Bernstein polynomials over a closed interval and then makes use of the tau method to determine the expansion coefficients to construct approximate solutions.This method can satisfy boundary conditions at infinity.The properties of Bernstein polynomials are presented and are utilized to reduce the solution of governing nonlinear equations and their associated boundary conditions to the solution of algebraic equations.Graphical results are presented to investigate the influence of the rotation ratioαon the radial velocity,azimuthal velocity and the induced velocities.A comparative study with the previous results of viscous fluid flow in the literature is made.展开更多
文摘In this paper the effects of temperature on the radial breathing modes （RBMs） and radial wave propaga- tion in multiwall carbon nanotubes （MWCNTs） are inves- tigated using a continuum model of multiple elastic isotropic shells. The van der Waals forces between tubes are simulated as a nonlinear function of interlayer spacing of MWCNTs. The governing equations are solved using a finite element method. A wide range of innermost radius-to-thickness ratio of MWCNTs is considered to enhance the investigation. The presented solution is verified by comparing the results with those reported in the literature. The effects of temperature on the van der Waals interaction coefficient between layers of MWCNTs are examined. It is found that the variation of the van der Waals interaction coefficient at high temperature is sensible. Subsequently, variations of RBM frequencies and radial wave propagation in MWCNTs with temperatures up to 1 600 K are illustrated. It is shown that the thick MWC- NTs are more sensible to temperature than the thin ones.
文摘The piezoelectric properties of relaxor ferroelectric 0.65Pb（Mg1/3,Nb2/3）O3-0.35PTO3 ceramic prepared by a sol-gel combustion method have been investigated as function of sintering temperature. The results show that its phase structure is near the morphoteropic phase boundary （MPB）, and outstanding electrical properties are obtained with this composition. The highest piezoelectric coefficients were observed for the samples sintered at temperature of 1200℃. In comparison with pure PMN （（1-x）Pb（Mg1/3Nb2/3）O3- （x）PbTiO3）, the substitution of 35% PT results in the decrease of sintered temperature and improved the relaxation behavior.
文摘In this investigation,a semi-numerical method based on Bernstein polynomials for solving off-centered stagnation flow towards a rotating disc is introduced.This method expands the desired solutions in terms of a set of Bernstein polynomials over a closed interval and then makes use of the tau method to determine the expansion coefficients to construct approximate solutions.This method can satisfy boundary conditions at infinity.The properties of Bernstein polynomials are presented and are utilized to reduce the solution of governing nonlinear equations and their associated boundary conditions to the solution of algebraic equations.Graphical results are presented to investigate the influence of the rotation ratioαon the radial velocity,azimuthal velocity and the induced velocities.A comparative study with the previous results of viscous fluid flow in the literature is made.
