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951.
Asymmetric tree-like branched networks are explored by geometric
algorithms. Based on the network, an analysis of the thermal
conductivity is presented. The relationship between effective
thermal conductivity and geometric structures is obtained by using
the thermal-electrical analogy technique. In all studied cases, a
clear behaviour is observed, where angle (δ ,θ ) among
parent branching extended lines, branches and parameter of the
geometric structures have stronger effects on the effective thermal
conductivity. When the angle δ is fixed, the optical
diameter ratio β* is dependent on angle θ .
Moreover, γ and m are not related to β * . The
longer the branch is, the smaller the effective thermal conductivity
will be. It is also found that when the angle θ < δ / 2,
the higher the iteration m is, the lower the thermal conductivity
will be and it tends to zero, otherwise, it is bigger than zero.
When the diameter ratio β 1< 0.707 and angle δ is
bigger, the optimal k of the perfect ratio increases with the
increase of the angle δ ; when β 1> 0.707, the
optimal k decreases. In addition, the effective thermal
conductivity is always less than that of single channel material.
The present results also show that the effective thermal
conductivity of the asymmetric tree-like branched networks does not
obey Murray's law. 相似文献
952.
Solutions to the equations describing materials with competing quadratic and cubic nonlinearities
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The Lie group theoretical method is used to study the equations
describing materials with competing quadratic and cubic
nonlinearities. The equations share some of the nice properties of
soliton equations. From the elliptic functions expansion method, we
obtain large families of analytical solutions, in special cases, we
have the periodic, kink and solitary solutions of the equations.
Furthermore, we investigate the stability of these solutions under
the perturbation of amplitude noises by numerical simulation. 相似文献
953.
在Hilbert空间的框架下,用一种变形的迭代格式xn+1=αnf(xn)+βnxn+γnTxn,研究一闭凸集合C上的非扩张映像的不动点问题,当满足适当的条件,且n→∞时,{xn}强收敛至T的一个不动点,并且此点也是某变分不等式的解.去掉了一些作者提出的相应条件,其结果改进了相应文献的一些近代结果. 相似文献
954.
不同品种大豆耐铝性的FTIR分析研究 总被引:3,自引:0,他引:3
利用傅里叶变换红外光谱(FTIR)法测定了2个不同耐铝性大豆品种在不同浓度铝处理下根、茎、叶的红外光谱。通过对各谱图的比较分析发现,除928~1 200 cm-1区域的FTIR差异比较明显外,未经处理的2个品种大豆红外光谱基本相似。而铝处理后2个品种大豆根、茎、叶的红外吸收峰形及峰值均与对照有较大的区别,且随铝浓度升高其FTIR区别越为明显。此外,结果表明浙春3号(铝敏感品种)的变化幅度比浙春2号(铝耐性品种)更为明显,这说明铝敏感大豆在铝胁迫下物质代谢受到了较大的影响。因此,采用FTIR法鉴别大豆不同耐铝性能够提供较为准确的结果,具有广泛的应用前景。 相似文献
955.
The stability of second-order differential equations is studied by using
their integrals. A system of second-order differential equations can be
considered as a mechanical system with holonomic constraints. A conserved
quantity of the mechanical system or a part of the system is obtained by
using the Noether theory. It is possible that the conserved quantity becomes
a Liapunov function and the stability of the system is proved by the
Liapunov theorem. 相似文献
956.
Dynamics of solitons in Bose-Einstein condensate with time-dependent atomic scattering length
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The evolution of solitons in Bose--Einstein condensates (BECs)
with time-dependent
atomic scattering length in an expulsive parabolic potential is studied. Based on
the extended hyperbolic function method, we successfully obtain the bright and dark
soliton solutions. In addition, some new soliton solutions in this model are found.
The results in this paper include some in the literature ({\em Phys. Rev. Lett.}
{\bf 94} (2005) 050402 and {\em Chin. Phys. Lett.} {\bf 22} (2005) 1855). 相似文献
957.
An extended mapping deformation method is proposed for finding new exact travelling wave solutions of nonlinear partial differential equations (PDEs). The key idea of this method is to take full advantage of the simple algebraic mapping relation between the solutions of the PDEs and those of the cubic nonlinear Klein-Gordon equation. This is applied to solve a system of variant Boussinesq equations. As a result, many explicit and exact solutions are obtained, including solitary wave solutions, periodic wave solutions, Jacobian elliptic function solutions and other exact solutions. 相似文献
958.
LI Hua-Mei 《理论物理通讯》2003,39(4):395-400
In this paper, we extend the mapping deformation method proposed by Lou. It is used to find new exacttravelling wave solutions of nonlinear partial differential equation or coupled nonlinear partial differential equations(PDEs). Based on the idea of the homogeneous balance method, we construct the general mapping relation betweenthe solutions of the PDEs and those of the cubic nonlinear Klein-Gordon (NKG) equation. By using this relation andthe abundant solutions of the cubic NKG equation, many explicit and exact travelling wave solutions of three systemsof coupled PDEs, which contain solitary wave solutions, trigonometric function solutions, Jacobian elliptic functionsolutions, and rational solutions, are obtained. 相似文献
959.
Starting from a special Bäcklund transform and a variable separation approach, a quite general variable separation solution of the
generalized (2+1)-dimensional perturbed nonlinear Schrödinger
system is obtained. In addition to the single-valued localized coherent soliton excitations like dromions, breathers, instantons, peakons, and previously revealed chaotic localized
solution, a new type of multi-valued (folded) localized excitation is derived
by introducing some appropriate lower-dimensional multiple valued
functions. 相似文献
960.
In the previous Letter (Zheng C L and Zhang J F 2002 Chin. Phys. Lett. 19 1399), a localized excitation of the generalized Ablowitz-Kaup-Newell-Segur (GAKNS) system was obtained via the standard Painlevé truncated expansion and a special variable separation approach. In this work, starting from a new variable separation approach, a more general variable separation excitation of this system is derived. The abundance of the localized coherent soliton excitations like dromions, lumps, rings, peakons and oscillating soliton excitations can be constructed by introducing appropriate lower-dimensional soliton patterns. Meanwhile we discuss two kinds of interactions of solitons. One is the interaction between the travelling peakon type soliton excitations, which is not completely elastic. The other is the interaction between the travelling ring type soliton excitations, which is completely elastic. 相似文献