Nucleon‐induced cross sections on magnesium isotopes, 24,25,26Mg, and silicon isotopes, 28,29,30Si, were evaluated for energies up to 3 GeV. Evaluation of nucleon‐scattering cross sections was performed by a consist...
Nucleon‐induced cross sections on magnesium isotopes, 24,25,26Mg, and silicon isotopes, 28,29,30Si, were evaluated for energies up to 3 GeV. Evaluation of nucleon‐scattering cross sections was performed by a consistent analysis of nuclear‐level structure and nucleon‐scattering data using a unified framework of a soft‐rotator model and coupled‐channel approach. The scattering cross sections for silicon isotopes were re‐analyzed based on two new considerations. First the silicon isotopes were assumed to be deformed nuclei having oblate shapes, second the more sophisticated form of optical‐potential energy dependence was used. The evaluation of the particle emissions was performed by using a nuclear‐model code system consisting of the GNASH code up to 150 MeV and the JQMD code above 150 MeV. The present results were compared with available experimental data and the LA 150 evaluation.
Recent simulations indicate that ellipsoids can pack randomly more densely than spheres and, remarkably, for axes ratios near 1.25∶1∶0.8 can approach the densest crystal packing (fcc) of spheres, with a packing frac...
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Recent simulations indicate that ellipsoids can pack randomly more densely than spheres and, remarkably, for axes ratios near 1.25∶1∶0.8 can approach the densest crystal packing (fcc) of spheres, with a packing fraction of 74%. We demonstrate that such dense packings are realizable. We introduce a novel way of determining packing density for a finite sample that minimizes surface effects. We have fabricated ellipsoids and show that, in a sphere, the radial packing fraction ϕ(r) can be obtained from V(h), the volume of added fluid to fill the sphere to height h. We also obtain ϕ(r) from a magnetic resonance imaging scan. The measurements of the overall density ϕavr, ϕ(r) and the core density ϕ0=0.74±0.005 agree with simulations.
The chemical mechanisms underlying the growth of cave formations such as stalactites are well known, yet no theory has yet been proposed which successfully accounts for the dynamic evolution of their shapes. Here we c...
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The chemical mechanisms underlying the growth of cave formations such as stalactites are well known, yet no theory has yet been proposed which successfully accounts for the dynamic evolution of their shapes. Here we consider the interplay of thin-film fluid dynamics, calcium carbonate chemistry, and CO2 transport in the cave to show that stalactites evolve according to a novel local geometric growth law which exhibits extreme amplification at the tip as a consequence of the locally-varying fluid layer thickness. Studies of this model show that a broad class of initial conditions is attracted to an ideal shape which is strikingly close to a statistical average of natural stalactites.
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..
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