城区爆破作业对环境的影响

本文用一个城区爆破作业的实例说明,只要采取可靠的技术措施,就可将爆破对环境的影响,如振动、噪声、飞石等,控制在允许的范围内,从而可以在人口稠密的城区顺利地进行较大规模的爆破施工,加快工程进度。     

关于中间激波的回顾与展望

中间激波是传统理论认为在物理上不可能实现的一类激波，但是，近年来在数值模拟中发现了它的结构，因此，在国际上引发了中间激波研究的高潮．本文首先系统地回顾了中间微波的研究历史和发展，给出了传统的激波演化性理论，并通过引用演化性理论，否定了中间激波的稳定存在．然后，介绍了近年来在中间激波方面的工作及进展情况，最后阐述了我们的一些看法．     

板带轧制过程中的三维接触摩擦模型

为解决压力加工中工具与工件间的接触摩擦问题，根据金属流动对摩擦的反作用，在轧辊和工件之间引入了一层极薄的摩擦单元并将其编入三维弹塑性大变形有限元程序。通过调节摩擦元尺寸厚度和β因子，实现了对薄板轧制过程中间介质的几何尺寸模拟和物理特征模拟。该法不用对摩擦力大小、方向及中性点位置进行假定，通过计算能够得到全部有关信息。     

Necessary and sufficient conditions for existence of stationary solutions of some nonlinear stochastic systems

At the state of statistical stationarity, the response of a nonlinear system under multiplicative random excitations can be either trivial or non-trivial, depending on the spectral levels of the excitations and the values of certain system parameters. Assuming that the random excitations are Gaussian white noises, the two types of response may be investigated by way of their stationary densities, which are obtainable for first order dynamical systems and for higher order dynamical systems belonging to the class of generalized stationary potential. Alternatively, the Lyapunov exponents can be computed for perturbation from either the trivial or non-trivial solution, since a negative sign for the greatest Lyapunov exponent provides both the necessary and sufficient conditions for the stability of sample functions with probability one. It is shown in two specific examples, that the boundary at which the greatest Lyapunov exponent changes its sign coincides with the boundary for regularity (or being normalizable) for the probability density in both the trivial and non-trivial solutions. Thus, the stability conditions in the strong sense of probability one and the weak sense in distribution are identical in these cases.     

计算机模拟升降法试验的研究

介绍了计算机模拟感度试验的原理，运用计算机模拟方法研究了升降法试验的初始参数选择对感度分布参数估计精度的影响，取得了对升降法有利的试验条件。     

用代数应力模型模化型腔充填过程中的紊流流动

针对型腔充填过程中的紊流流动，用代数应力模型研究紊流流动现象．成功地将代数应力模型引入ＰＨＯＥＮＩＣＳ软件中，完成了恒温流体充填过程三维时均速度和自由表面的计算模拟．与实验结果相比说明，本文基于ＰＨＯＥＮＩＣＳ软件开发的充填模拟具备了对复杂型腔充填过程的数值计算．     

A non-singular continuum theory of dislocations

We develop a non-singular, self-consistent framework for computing the stress field and the total elastic energy of a general dislocation microstructure. The expressions are self-consistent in that the driving force defined as the negative derivative of the total energy with respect to the dislocation position, is equal to the force produced by stress, through the Peach-Koehler formula. The singularity intrinsic to the classical continuum theory is removed here by spreading the Burgers vector isotropically about every point on the dislocation line using a spreading function characterized by a single parameter a, the spreading radius. A particular form of the spreading function chosen here leads to simple analytic formulations for stress produced by straight dislocation segments, segment self and interaction energies, and forces on the segments. For any value a>0, the total energy and the stress remain finite everywhere, including on the dislocation lines themselves. Furthermore, the well-known singular expressions are recovered for a=0. The value of the spreading radius a can be selected for numerical convenience, to reduce the stiffness of the dislocation equations of motion. Alternatively, a can be chosen to match the atomistic and continuum energies of dislocation configurations.     

Phragmen-Lindelöf alternative results for the initial boundary problem of stokes equation

In this paper we prove Phragmén-Lindelöf type alternative for the initial boundary problem of Stokes equation, i. e. we show that the energy expression for the solution of the initial boundary problem must either grow exponentially or decay exponentially with axial distance from the end of a semi-infinite strip. For the case of decay, we also establish the pointwise estimate for the maximum module of the Stokes flow and present a method for obtaining explicit bounds for the total energy.Project supported by the National Natural Science Foundation of China and Zhongshan University Science Foundation     

ON THE MECHANISM OF TURBULENT COHERENT STRUCTURE(II)──A PHYSICAL MODEL OF COHERENT STRUCTURE FOR THE ROUGH BOUNDARY LAYER

In this paper, the differences of turbulent coherent structure between the smooth and rough boundary layers are analysed. Based on the discussing the transient properties from the smooth wall to the rough wall, the physical model of coherent structure for the rough boundary layer are established. The width of slowly-moving turbulent spot and the bursting time are obtained, which are in agreement with experimental results.The project supported by the National Nature Science Foundation of China     

基于石墨烯的光纤湿度传感研究

将还原氧化石墨烯(r GO)沉积在侧边抛磨光纤(SPF)上制作了一种新型的光纤湿度传感器。在高湿度区域[相对温度(RH)为70%~95%],传感器的光功率变化达到6.9 d B,尤其在RH为75%~95%区域,传感器对湿度变化能实现相关系数为98.2%的线性响应,灵敏度可达0.31 d B/(%RH),响应速度快于0.13(%RH)/s,并且具有很好的可重复性。对传感机理的理论分析可以解释实验结果,并且表明这种基于石墨烯的光纤传感器亦可广泛应用于其他种类化学气体的探测。这种全新机理的光学传感器是对石墨烯电化学传感器的一种很好的补充,并将促进石墨烯在化学传感技术中的应用。