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81.
横观各向同性多孔超弹性矩形板的单向拉伸 总被引:2,自引:0,他引:2
利用横观各向同性超弹性材料的广义neo-Hookean应变能函数研究了含有多个微孔的超弹性矩形板在单向拉伸作用下的有限变形和受力分析.给出了含有某种对称性分布的多个微孔的矩形板的变形模式,通过求解该变形模式满足的微分方程,将它用两个参数表示出来.可应用最小势能原理导出变分近似解,从而得到矩形板的变形和应力分布的解析解.分析了板中微孔的增长及微孔边缘应力的分布情况,讨论了板的各向异性程度及微孔的大小和孔间距离的影响,得到了单个、三个及五个微孔板中微孔的增长变形和孔边应力分布的一些基本规律规律,并进行了相互比较. 相似文献
82.
We introduce two types of finite difference methods to compute the L-solution and the proper viscosity solution recently proposed by the second author for semi-discontinuous solutions to a class of Hamilton-Jacobi equations. By regarding the graph of the solution as the zero level curve of a continuous function in one dimension higher, we can treat the corresponding level set equation using the viscosity theory introduced by Crandall and Lions. However, we need to pay special attention both analytically and numerically to prevent the zero level curve from overturning so that it can be interpreted as the graph of a function. We demonstrate our Lax-Friedrichs type numerical methods for computing the L-solution using its original level set formulation. In addition, we couple our numerical methods with a singular diffusive term which is essential to computing solutions to a more general class of HJ equations that includes conservation laws. With this singular viscosity, our numerical methods do not require the divergence structure of equations and do apply to more general equations developing shocks other than conservation laws. These numerical methods are generalized to higher order accuracy using weighted ENO local Lax-Friedrichs methods as developed recently by Jiang and Peng. We verify that our numerical solutions approximate the proper viscosity solutions obtained by the second author in a recent Hokkaido University preprint. Finally, since the solution of scalar conservation law equations can be constructed using existing numerical techniques, we use it to verify that our numerical solution approximates the entropy solution.
83.
Kathryn E. Hare Maria Roginskaya 《Proceedings of the American Mathematical Society》2003,131(1):165-174
In this paper we derive a formula relating the energy and the Fourier transform of a finite measure on the -dimensional torus which is similar to the well-known formula for measures on .
We apply the formula to obtain estimates on the Hausdorff dimension of Riesz product measures. These give improvements on the earlier, classical results which were based on completely different techniques.
84.
Daniel Aronov 《Surface science》2007,601(21):5042-5049
We observe a pronounced variation of wettability properties in solid state materials induced by a low-energy electron beam. The phenomenon occurs in several stages characterized by various mechanisms. We show that for low electron doses the irradiation leads to decrease in the wetting of a dielectric surface due to induced surface electric potential. The higher electron charge leads to formation of a chemical monolayer on material’s surface. It has been found that the electron irradiation strongly modifies the surface free energy of SiO2 by decreasing its total surface free energy value, almost twice. However, electron-induced variations of dispersive and polar components of the surface free energy are quite different and depend of incident electron charge. 相似文献
85.
Traditional ligand-field theory has to be improved by taking into account
both “pure electronic” contribution and electron-phonon interaction one
(including lattice-vibrational relaxation energy). By means of improved
ligand-field theory, R1,
R2, R3',
R2', and R1'
lines, U band, ground-state zero-field-splitting (GSZFS), and ground-state g factors of ruby and/or
GSGG:Cr3+ as well as thermal shifts of GSZFS, R1 line and R2 line of ruby have been calculated. The results are
in very good agreement with the experimental data. Moreover, it is found
that the value of cubic-field parameter given by traditional ligand-field
theory is inappropriately large. For thermal shifts of GSZFS, R1 line and R2 line of ruby, several conclusions have also been obtained. 相似文献
86.
HE Feng YU Wei LU Pei-Xiang XU Han SHEN Bai-Fei QIAN Lie-Jia LI Ru-Xin XU Zhi-Zhan 《理论物理通讯》2005,43(5):910-914
With the development of photocathode rf electron gun, electrons
with high-brightness and mono-energy can be obtained easily. By
numerically solving the relativistic equations of motion of an
electron generated from this facility in laser fields modelled by
a circular polarized Gaussian laser pulse, we find the electron
can obtain high energy gain from the laser pulse. The corresponding acceleration distance for this electron driven by the ascending part of the laser pulse is much longer than the
Rayleigh length, and the light amplitude experienced on the
electron is very weak when the laser pulse overtakes the electron.
The electron is accelerated effectively and the deceleration can
be neglected. For intensities around 1019 W•μm2/cm2, an
electron's energy gain near 0.1 GeV can be realized when its
initial energy is 4.5 MeV, and the final velocity of the energetic
electron is parallel with the propagation axis. The energy gain
can be up to 1 GeV if the intensity is about 1021 W•μm2/cm2. The final energy gain of the electron as a function of its initial conditions and the parameters of the laser beam has
also been discussed. 相似文献
87.
FAN Hong-Yi JIANG Zhong-Hua 《理论物理通讯》2005,44(12)
We show how to directly use the generalized Feynman-Hellmann theorem, which is suitable for mixed state ensemble average, to derive the internal energy of Hamiltonian systems. A concrete example, which is a two coupled harminic oscillators, is used for elucidating our approach. 相似文献
88.
V. Yu. Grishina L. A. Kondratyuk A. Sibirtsev M. Büscher S. Krewald U. -G. Meißner F. P. Sassen 《The European Physical Journal A - Hadrons and Nuclei》2005,25(1):159-164
We present predictions for the K-α scattering length obtained within the framework of the multiple-scattering approach. Evaluating the pole position of the K-α scattering amplitude within the zero-range approximation, we find a loosely bound K-α state with a binding energy of ER = - 2,..., - 7 MeV and a width ΓR = 11,..., 18 MeV. We propose to measure the K-α scattering length through the final-state interaction between the α and K--meson produced in the reaction dd↦αK+K-. It is found that the K-α invariant-mass distribution from this reaction at energies near the threshold provides a new tool to determine the s-wave K-α scattering length. 相似文献
89.
Vollmer A Jurchescu OD Arfaoui I Salzmann I Palstra TT Rudolf P Niemax J Pflaum J Rabe JP Koch N 《The European physical journal. E, Soft matter》2005,17(3):339-343
We use ultraviolet photoelectron spectroscopy to investigate the effect of oxygen and air exposure on the electronic structure of pentacene single crystals and thin films. It is found that O2 and water do not react noticeably with pentacene, whereas singlet oxygen/ozone readily oxidize the organic compound. Also, we obtain no evidence for considerable p-type doping of pentacene by O2 at low pressure. However, oxygen exposure lowers the hole injection barrier at the interface between Au and pentacene by 0.25 eV, presumably due to a modification of the Au surface properties. 相似文献
90.
The initial condition Ωde(zini)=n2(1+zini)-2/4 at zini=2000 widely used to solve the differential equation of the density of the new agegraphic dark energy (NADE) Ωde, makes the NADE model be a single-parameter dark-energy cosmological model. However, we find that this initial condition is only applicable in a flat universe with only dark energy and pressureless matter. In fact, in order to obtain more information from current observational data, such as the cosmic microwave background (CMB) and the baryon acoustic oscillations (BAO), we need to consider the contribution of radiation. For this situation, the initial condition mentioned above becomes invalid. To overcome this shortage, we investigate the evolutions of dark energy in the matter-dominated and the radiation-dominated epochs, and obtain a new initial condition Ωde(zini)=n2(1+zini)-2(1+√F(zini)2/4 at zini=2000, where F(z)≡Ωr0(1+z)/[Ωm0+Ωr0(1+z)] with Ωr0 and Ωm0 being the current density parameters of radiation and pressureless matter, respectively. This revised initial condition is applicable for the differential equation of Ωde obtained in the standard Friedmann-Robertson-Walker (FRW) universe with dark energy, pressureless matter, radiation, and even spatial curvature, and can still keep the NADE model being a single-parameter model. With the revised initial condition and the observational data of type Ia supernova (SNIa), CMB, and BAO, we finally constrain the NADE model. The results show that the single free parameter n of the NADE model can be constrained tightly. 相似文献