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81.
82.
The viscoelastic behavior of carbon-black-filled rubber under small oscillatory loads superimposed on large static deformation
is dealt with. In this class of problems, as the strain amplitudes of the load increase, the dynamic stiffness decreases,
and this phenomenon is known as the Payne effect. Besides the effects of the static deformation and the frequencies of the
superimposed dynamic load, the Payne effect is considered in this study. Influence factors are introduced in this model in
order to consider the influence of static predeformation, the dynamic-strain-dependent properties, and frequency-dependent
properties. For simplicity, separation of the three dominant variables, frequency, prestatic deformation, and dynamic amplitude
of strain, is assumed. The Kraus model is used for describing the Payne effect. Dynamic tension tests are executed to obtain
the model parameters and also for the verification of the proposed model. The suggested constitutive equation shows reasonable
agreement with test data. 相似文献
83.
Transition between layered and filamentary types of anisotropy in layered superconducting structures
D. A. Kuptsov 《Annalen der Physik》1992,504(4):296-301
A model of layered superconducting structure consisting of alternating anisotropic superconducting layers S1 and S2 with different transition temperatures is considered. It is shown that due to competition between two origins of anisotropy - effective-mass anisotropy of individual layers and proximity-induced anisotropy the effective anisotropy of the whole system signficiantly varies temperature. The components of the effective-mass tensor mc (along the anisotropy axis) and ma (perpendicular to the anisotropy axis) strongly depend upon temperature. This may lead to transition between layered (mc > ma) and quasi one-dimensional (mc < ma) types of anisotropy as well as to biaxial-type anisotropy which is also temperature dependent. The field distribution in a tilted vortex in a biaxial superconductor is calculated. The change in the properties of the vortex lattice with temperature in such systems is also investigated. The properties of YBa2Cu3Ox/PrBa2Cu3Oy multilayers are discussed in this connection. 相似文献
84.
InAs/GaSb/AlSb resonant tunneling spin device concepts 总被引:1,自引:0,他引:1
David Z. -Y. Ting Xavier Cartoix 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):350
We discuss device concepts for creating spin-polarized current sources without external magnetic fields, using non-magnetic 6.1 Å semiconductor resonant tunneling structures. Spin filters, spin pumps, and spin transistors that exploit structural and bulk inversion asymmetries will be examined. 相似文献
85.
程治国 《宁波大学学报(理工版)》2004,17(1):28-31
提出了在无外力作功的情况下,具有Bauschinger效应的弹塑性材料处于屈服状态产生自发的塑性流动时应满足的条件.这个条件不仅与材料的力学性能有关,而且还处决于材料的具体的载荷边界条件和变形.举例说明了承受拉一扭组合的薄壁圆筒中,采用组合强化模型时,产生塑性流动的具体条件. 相似文献
86.
87.
应用密度矩阵方程计算了四能级原子系统中三阶非线性极化率随信号光和探针光频率失谐的变化关系。结果表明,由于量子干涉对信号光强度的敏感性,使四能级原子介质的交叉Kerr非线性作用大大增强,与三能级系统相比,四能级原子介质的Kerr非线性系数可增强两个数量级。 相似文献
88.
Scaling impacted structures 总被引:1,自引:0,他引:1
Summary The problem of non-scalability of structures under impact loads caused by strain-rate effects is solved in this article by properly correcting the impact velocity. The technique relies on the use of an alternative dimensionless basis, together with a mathematical model which allows the calculation of a correction factor for the impact velocity. This new velocity, when applied to the model, makes it to assure the satisfaction of the scaling laws. The indirect similitude method detailed here is applied to two strain-rate sensitive structures, a double plate under in-plane impact and a beam subjected to a blast load. The results show a very good agreement so that the model and a prototype made from strain rate sensitive materials behave the same.accepted for publication 3 March 2004 相似文献
89.
S. Sasa A. Nakashima Y. Nakajima M. Inoue 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):224
We fabricated nanoscale open-dot structures in an InAs surface inversion layer using an atomic-force-microscope oxidation process. Due to its superior nanofabrication capability, small open-dot structures with the feature size ranging between 100 and 300 nm were successfully fabricated. The magnetoresistance signal measured at 4.2 K showed reproducible fluctuations and a periodic oscillation component that varies in both amplitude and periodicity depending on the dot size. We show that the period of the oscillations corresponds to that of the Aharonov–Bohm effect and propose that the possible mechanism for the oscillations is due to the formation of a one-dimensional electron channel enclosing the open-dot structure as a result of the electron transfer from the InAs oxide to InAs. 相似文献
90.
K. Suzuki S. Miyashita K. Takashina Y. Hirayama 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):232
We investigate the quantum Hall effect (QHE) in the InAs/GaSb hybridized electron–hole system grown on a conductive InAs substrate which act as a back-gate. In these samples, the electron density is constant and the hole density is controlled by the gate-voltage. Under a magnetic field perpendicular to the sample plane, the QHE appears along integer Landau-level (LL) filling factors of the net-carriers, where the net-carrier density is the difference between the electron and hole densities. In addition, longitudinal resistance maxima corresponding to the crossing of the extended states of the original electron and hole LLs make the QHE regions along integer-νnet discontinuous. Under tilted magnetic fields, these Rxx maxima disappear in the high magnetic field region. The results show that the in-plane magnetic field component enhances the electron–hole hybridization and the formation of minigaps at LL crossings. 相似文献