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81.
82.
3 低维体系的生长制备和分析3 .1 生长制备传统的电子材料和器件加工中使用以下几种工艺来形成细小尺寸的图形 .1 )光刻和电子束刻蚀 :最小刻蚀尺度受衍射限制 ,对可见光 ,最小刻蚀尺度~ 0 .1 5μm,使用软 X射线可降至 0 .0 1μm,高能电子束刻蚀可达 0 .0 2 μm,若使用无机抗蚀剂还可降到1 nm,可用来形成量子线和量子点 .2 )腐蚀 :包括化学腐蚀和等离子体腐蚀 .化学腐蚀必然留下一些残留物 ;等离子体工艺过程中的 H原子可能进入材料 ,在 50 nm或更深的深度内改变掺杂浓度的深度分布 .3 )离子注入 :虽然使用适当厚度的掩膜可获得注入区和… 相似文献
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Periodic, quasiperiodic and chaotic discrete breathers in a parametrical driven two-dimensional discrete diatomic Klein--Gordon lattice
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We study a two-dimensional (2D) diatomic lattice of anharmonic
oscillators with only quartic nearest-neighbor interactions, in
which discrete breathers (DBs) can be explicitly constructed by an
exact separation of their time and space dependence. DBs can stably
exist in the 2D discrete diatomic Klein--Gordon lattice with hard
and soft on-site potentials. When a parametric driving term is
introduced in the factor multiplying the harmonic part of the
on-site potential of the system, we can obtain the stable
quasiperiodic discrete breathers (QDBs) and chaotic discrete
breathers (CDBs) by changing the amplitude of the driver. But the
DBs and QDBs with symmetric and anti-symmetric profiles that are
centered at a heavy atom are more stable than at a light atom,
because the frequencies of the DBs and QDBs centered at a heavy atom
are lower than those centered at a light atom. 相似文献
85.
基于绝对节点坐标的多柔体系统动力学高效计算方法 总被引:4,自引:0,他引:4
绝对节点坐标法已经被广泛应用于柔性多体系统的动力学研究之中, 但是其计算效率问题尚未得到很好的解决. 基于绝对节点坐标方法计算弹性力及其对广义坐标的偏导数矩阵(Jacobi矩阵), 通常是基于第二类Piola-Kirchhoff应力张量来完成, 计算效率不高.根据虚功原理并采用第一类Piola-Kirchhoff应力张量的方法直接推导得到了弹性力及其Jacobi矩阵的解析表达式. 基于不同方法所得的数值算例结果对比研究表明, 该方法可使计算效率大大提高. 相似文献
86.
Z-scan analysis of high-order nonlinear refraction effect induced by using elliptic Gaussian beam
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The irradiance of an elliptic Gaussian beam that is high
enough to excite high-order nonlinear refraction effect is used to
calculate the normalized on-axis transmittance function in the z-scan
technique by introducing complex beam parameters which make the
calculation simpler. The transmittance formula is applied to the
first-, first two-, and first three-order nonlinearities. Numerical
evaluation shows that the symmetry no longer holds when using an
elliptic Gaussian beam instead of a circular Gaussian beam. A
distortion is observed in the central part of the curve, which
decreases as ellipticity increases. Moreover, the variation of the
normalized peak-valley difference decreases as ellipticity
decreases. 相似文献
87.
The 3D solitons and vortices in 3D discrete monatomic lattices with cubic
and quartic nonlinearity
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By virtue of the method of multiple-scale and the quasi-discreteness
approach, we have discussed the nonlinear vibration equation of a 3D
discrete monatomic lattice with its nearest-neighbours interaction. The 3D
simple cubic lattices have the same localized modes as a 1D discrete
monatomic chain with cubic and quartic nonlinearity. The nonlinear vibration
in the 3D simple cubic lattice has 3D distorted solitons and 3D envelop
solitons in the direction of $k_{x}=k_{y}=k_{z}=k$ and $k=\pm
\pi$/6$a_{0}$ in the
Brillouin zone, as well as has 3D vortices in the direction of
$k_{x}=k_{y}=k_{z}=k$ and $k=\pm \pi$/$a_{0}$ in the Brillouin zone. 相似文献
88.
Existences and stabilities of bright and dark breathers in a general one-dimensional discrete monatomic Chain
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A general one-dimensional discrete monatomic model is investigated
by using the multiple-method. It is proven that the discrete bright
breathers (DBBs) and discrete dark breathers (DDBs) exist in this
model at the anti-continuous limit, and then the concrete models of
the DBBs and DDBs are also presented by the multiple-scale approach
(MSA) and the quasi-discreteness approach (QDA). When the results
are applied to some particular models, the same conclusions as those
presented in corresponding references are achieved. In addition, we
use the method of the linearization analysis to investigate this
system without the high order terms of $\varepsilon$. It is found
that the DBBs and DDBs are linearly stable only when coupling
parameter $\chi$ is small, of which the limited value is obtained by
using an analytical method. 相似文献
89.
Existence and Stability of Two-Dimensional Compact-Like Discrete Breathers in Discrete Two-Dimensional Monatomic Square Lattices
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Two-dimensional compact-like discrete breathers in discrete two-dimensional monatomic square lattices are investigated by discussing a generalized discrete two-dimensional monatomic model. It is proven that the two- dimensional compact-like discrete breathers exist not only in two-dimensional soft Φ4 potentials but also in hard two-dimensional Φ4 potentials and pure two-dimensional K4 lattices. The measurements of the two-dimensional compact-like discrete breather cores in soft and hard two-dimensional Φ4 potential are determined by coupling parameter K4, while those in pure two-dimensional K4 lattices have no coupling with parameter K4. The stabilities of the two-dimensional compact-like discrete breathers correlate closely to the coupling parameter K4 and the boundary condition of lattices. 相似文献
90.
高温氧化是限制钒合金应用的主要原因之一。利用第一性原理计算了Ti、Cr杂质原子掺入钒基体后,O在钒合金中的杂质形成能的变化。结果表明:O杂质原子在钒中占据八面体间隙位更稳定,且杂质形成能为-4.65eV,Ti掺杂会降低O的杂质形成能,使O在晶体内部扩散更容易,Cr掺杂的情况与Ti掺杂相反。并且还计算了体系电子结构、布局分布和电荷密度,进一步分析所得到的结论与杂质形成能的计算结果一致。 相似文献