Carbon nanotubes were catalytically grown by negative bias-enhanced hot filament chemical vapor deposition at low substrate temperature (550°C) and their growth was investigated by scanning electron microscopy. I...
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Carbon nanotubes were catalytically grown by negative bias-enhanced hot filament chemical vapor deposition at low substrate temperature (550°C) and their growth was investigated by scanning electron microscopy. It is found whether the carbon nanotubes could be orientationally grown at low temperature depended on the plasma power and carbon nanotubes could not be grown if the pressure was too low. The analysis results by the related theory indicate that the interaction of the strong electrical field formed by plasma with the catalyst particles resulted in the orientation growth of carbon nanotubes when the plasma power was large and the diffusion of the particles containing carbon at low pressure was too fast to grow the carbon nanotubes.
Some integral identities of smooth solution of inhomogeneous initial boundary value problem of Ginzburg-Landau equations were deduced, by which a priori estimates of the square norm on boundary of normal derivative an...
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Some integral identities of smooth solution of inhomogeneous initial boundary value problem of Ginzburg-Landau equations were deduced, by which a priori estimates of the square norm on boundary of normal derivative and the square norm of partial derivatives were obtained. Then the existence of global weak solution of inhomogeneous initial-boundary value problem of Ginzburg-Landau equations was proved by the method of approximation technique and a priori estimates and making limit.
We prove the existence of solutions of the static Landau-Lifshitz equation with multi- direct effective field and with Dirichlet boundary condition,and establish the stability of the solution of Landau-Lifshitz equati...
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We prove the existence of solutions of the static Landau-Lifshitz equation with multi- direct effective field and with Dirichlet boundary condition,and establish the stability of the solution of Landau-Lifshitz equation with respect to time.
The direct simulation Monte Carlo (DSMC) method is one of the most popular numerical methods used to model rarefied gas environment flows. In order to predict the accuracy of a solution obtained by the DSMC method we ...
The direct simulation Monte Carlo (DSMC) method is one of the most popular numerical methods used to model rarefied gas environment flows. In order to predict the accuracy of a solution obtained by the DSMC method we have to be able to estimate its accuracy. In the work presented here we have developed a technique to estimate the numerical accuracy of the DSMC method. This paper presents a derivation of expressions of the variance of the DSMC estimators of number density and translational temperature, and the corresponding comparison with the empirical variance. A discussion of the deterministic numerical errors corresponding to typical DSMC parameters such as the time step, cell volume, and total number of simulated particles is given. Moreover, a comparison of two different DSMC schemes, No Time Counter (NTC) and Majorant Frequency (MF), is made.
Using Banach fixed point theorem and a priori estimate,the existence of periodic and almost periodic solutions of Ca massa-Holm type equation with a nonlinear boundary condition are respectively proved when g(x,t)is p...
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Using Banach fixed point theorem and a priori estimate,the existence of periodic and almost periodic solutions of Ca massa-Holm type equation with a nonlinear boundary condition are respectively proved when g(x,t)is periodic or almost periodic function of time t.
Chaos is closely associated with homoclinic orbits in deterministic nonlinear dynamics. In this note, the homoclinic orbits of the doubly periodic Davey-Stewartson equation are obtained by using the Hirota's bilin...
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Chaos is closely associated with homoclinic orbits in deterministic nonlinear dynamics. In this note, the homoclinic orbits of the doubly periodic Davey-Stewartson equation are obtained by using the Hirota's bilinear methods, which is important to the study on the global property of the doubly periodic Davey-Stewartson equation.
With finite-element software ANSYS 7.0 and simple thermal-mechanical coupling constitutive relations,the buckling failure of preloaded cylindrical shell irradiated by high power laser beam was studied by numerical si...
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With finite-element software ANSYS 7.0 and simple thermal-mechanical coupling constitutive relations,the buckling failure of preloaded cylindrical shell irradiated by high power laser beam was studied by numerical simulations. The buckling mode and buckling critical loading were analysed for different preloading conditions. The influence of laser intensity, beam irradiation time, preloading conditions and geometric parameters of cylindrical shell on the buckling mode were discussed. The numerical results show that: ① the buckling deformation of the cylindrical shell was concentrated in the area of laser spot and the radial buckling was the main buckling mode, ② a linear relationship between the buckling eigenvalue and the maximum temperature at the center of laser spot was approached, ③ the buckling failure of cylindrical shell was attributed to the coupling effect of the material softening and the radial deformation in the laser spot, and hence to raise the stiffness of the material would enhance the ability for anti-irradiation of structure substantially..
The penetration behavior and perforation characteristics of Kevlar/Epoxy laminates with various thickness in quasi-static and ballistic perforation penetrated by steel projectiles with different noses are investigated...
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The penetration behavior and perforation characteristics of Kevlar/Epoxy laminates with various thickness in quasi-static and ballistic perforation penetrated by steel projectiles with different noses are investigated. Quasi-static tests are conducted on MTS810 testing system. The results indicate that global deformation is the major mechanism of energy absorption and woven laminates exhibit larger energy dissipation than that of angle-plied laminates. Therefore, the woven laminates have better quasi-static penetration resistance. Ballistic tests with velocity of 200-700 m/s are executed by using a powder gun with 7.62 mm barrel. Comparing ballistic experimental results with those under quasi-static condition, both the perforation performance and the failure modes are related closely to the speed of penetrator. Quite different from quasi-static tests, ballistic tests indicate that thick angle-plied laminate targets are even better than woven laminates in resisting ballistic impact. It is observed that the damage zone of the laminate is localized highly with the increasing of the impact velocity and correspondingly, the failure modes are more manifold. The shape of projectile noses affects the impact resistance of laminated Kevlar significantly in the range of velocity around the ballistic limit..
The fluid-filled semicircular canals (SCCs) of the vestibular system are used by all vertebrates to sense angular rotation. Despite masses spanning seven decades, all mammalian SCCs are nearly the same size. We propos...
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The fluid-filled semicircular canals (SCCs) of the vestibular system are used by all vertebrates to sense angular rotation. Despite masses spanning seven decades, all mammalian SCCs are nearly the same size. We propose that the SCC represents a sensory organ that evolution has “optimally designed.” Four geometric parameters characterize the SCC, and “building materials” of given physical properties are assumed. Identifying physical and physiological constraints on SCC operation, we find the most sensitive SCC has dimensions consistent with available data. Since natural selection involves optimization, this approach may find broader use in understanding biological structures.
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