弹塑性结构在外载和温度作用下的安定分析

本文在考虑外载和温度的缓慢变化下，提出了一个新的运动安定定理。同时，在此基础上，又导出了既简单又适用的增量破坏准则．文末也以实例说明了它的应用。     

Maps Between Deformed and Ordinary Gauge Fields

In this paper, we introduce a map between the q-deformed gauge fields defined on the GL_q(N) -covariant quantum hyperplane and the ordinary gauge fields. Perturbative analysis of the q-deformed QED at the classical level is presented and gauge fixing à la BRST is discussed. Another star product defined on the hybrid (q,h) -plane is explicitly constructed.     

Two nontrivial solutions for quasilinear periodic equations

In this paper we study a nonlinear periodic problem driven by the ordinary scalar p-Laplacian and with a Carathéodory nonlinearity. We establish the existence of at least two nontrivial solutions. Our approach is variational based on the smooth critical point theory and using the ``Second Deformation Theorem".

     

New Deformation of Para-Bose Statistics

We propose commutation relations for a single mode -deformed para-Bose oscillator. In this new deformation of para-Bose statistics the distribution function has the same form as in the para-Bose statistics. Furthermore, we show analogies between the coherent states of -deformed and q-deformed para-Bose statistics.     

On the extremality of quasiconformal mappings and quasiconformal deformations

Given a family of quasiconformal deformations such that has a uniform bound , the solution of the Löwner-type differential equation

is an -quasiconformal mapping. An open question is to determine, for each fixed , whether the extremality of is equivalent to that of . The note gives this a negative approach in both directions.

     

Vibrational excitation of molecules in a lattice due to shock induced molecular deformation

A simple formalism is developed to calculate the rate of internal vibrational excitation of a molecule in a lattice due to abrupt deformation of the bonds of the molecule as a result of the application of a shock pulse to the lattice. The excitation rate is calculated as a function of rise time of the pulse and peak pressure for the case of 1,3,5-trinitro, 1,3,5-triazocyclohexane. It is shown that large vibrational excitation rates can be achieved if the rise time of the shock pulse is in the order of the period of vibration of the bond. The possible role of this process in shock induced chemical reactions in solids is considered.     

Effects of twin and stacking faults on the deformation behaviors of Al nanowires under tension loading

The effects of twin spacing and temperature on the deformation behavior of nanotwinned Al under tensile loading are investigated using a molecular dynamic(MD) simulation method.The result shows that the yield strength of nanotwinned Al decreases with the increase of twin spacing,which is related to the repulsive force between twin boundary and the dislocation.The result also shows that there is no strain-hardening at the yield point.On the contrary,the stress is raised by strain hardening in the plastic stage.In addition,we also investigate the effects of stacking fault thickness and temperature on the yield strength of the Al nanowire.The simulation results indicate that the stacking fault may strengthen the Al nanowire when the thickness of the stacking fault is below a critical value.     

形变张量的特征值与Boussinesq方程组的正则性估计

讨论了二维及三维满足周期边界条件的Boussinesq方程初边值问题的局部正则解在有限时间内爆破的可能性.在二维情况下,用形变张量的特征值给出温度梯度的L2估计,从中看出若流体微团变形的速率大,则解爆破的可能性就大.在三维情况下,用形变张量的特征值和温度的偏导给出涡量的L2估计,从中发现若流体微团在大部分时间内一般是平面拉伸,且温度的偏导较小时,解爆破的可能性就大;若一般是线性拉伸,温度的偏导又不任意增大时,解爆破的可能性就小.     

Comment on “A comparison of the von Mises and Hencky equivalent strains for use in simple shear experiments”

Onaka has shown (2010) that the Hencky equivalent strain is the appropriate quantity to represent the degree of severe plastic deformation based on simple-shear deformation. In a recent paper, Shrivastava et al. have criticized (2011) the Onaka paper and stated that the Hencky formulation does not apply to large simple-shear deformation. In this response, it is shown that this claim of Shrivastava et al. is not consistent with recent accepted knowledge on the Hencky strain.     

天然气水合物分解对地层稳定性影响的离心机实验模拟

水合物分解后将引起地层强度的降低,可能造成海床沉陷、滑塌以及海洋结构物基础的破坏。针对该问题,首先以南海浅层粉砂为沉积物骨架,采用生物厌氧发酵技术合成水合物沉积物,然后进行水合物热分解引起地层响应的离心机实验模拟,获得了水合物分解引起地层变形与滑塌的特征以及孔隙压力发展的物理过程,为研究水合物分解引起海床失稳的条件进行了新的尝试。