颗粒介质弹性参数测量方法及装置研究

本文发展了一种实施简便的颗粒介质弹性参数测量方法,设计并加工了基于该方法的实验装置。利用加载设备对该实验装置在一个方向上加卸载,在加载方向和与之垂直的另一方向上测量载荷和位移后即可获得颗粒介质的等效弹性模量和泊松比。该实验装置的容器还可方便地调节尺寸,适用于测量不同粒径颗粒堆积在不同大小容器时的弹性参数。本文还研究了尺寸效应的影响,分析了容器尺寸和颗粒粒径分别对介质弹性参数的影响规律。     

双"单电桥"法测量低电阻中的实用技巧例举

主要介绍了双"单电桥"法测量低电阻的基本原理与双"单电桥"法测量低电阻的几种实用技巧.     

Phase Transition and Critical Phenomenon Occurring in Granular Matter

We investigate the granular flow states in a channel with bottleneck by molecular dynamics simulations.Our study is restricted only on a selected key area rather than on the whole system to focus on the flow properties of a single granular state.A random force field is introduced to control the granular temperature.It is also pointed out that the flow rate in the granular flow can be correlated with the pressure,which leads us to carry out a comprehensive study similar to the classical study for general liquid-gas phase transition.Our results show that the dilute flow state and the dense flow state of the granules are similar to the gas state and the liquid state of general substances,respectively,and the properties of phase transition and critical phenomenon are also similar to those occurring in general substances.     

颗粒堆准静态崩塌及慢速流动过程中的堆结构研究

运用自行设计的实验装置并结合颗粒跟踪与成像技术,系统地研究了不同堆积程度的颗粒堆在准静态崩塌过程中的滑移行为.实验发现在颗粒堆中一部分颗粒沿着斜下方向滑动,而另一部分颗粒则几乎没有滑动.精确的数据分析还表明颗粒堆的滑动部分具有明显的层状结构特征,在每一滑动层中颗粒的滑移量基本相同,且各滑动层之间近似相互平行.这些滑动层与水平面的夹角约在40—50之间,与静态层表面与水平面的夹角一致.各滑动层中颗粒的滑移量随其距静态层表面的距离而线性的增加.不同堆积程度的颗粒堆的静态部分基本上不随堆积体积而改变.     

小型风光互补发电演示装置

研制了适用于大学物理演示实验教学的小型风光互补发电演示装置,该装置由叶片、风力发电机、光伏太阳能电池板、控制器、蓄电池、逆变器、负载等几部分组成.整个系统以光电互补控制器为核心,经由风力发电机与光伏太阳能电池板将风能和太阳光能转变为电能,并将其储存于蓄电池中供负载使用.该装置展示了风力发电系统的组成,演示了风力发电原理和相关空气动力学原理.     

Microcanonical Phase Diagram of the BEG and Ising Models

The density of states of long-range Blume-Emery-Griffiths(BEG) and short-range Ising models are obtained by using Wang-Landau sampling with adaptive windows in energy and magnetization space.With accurate density of states,we are able to calculate the microcanonical specific heat of fixed magnetization introduced by Kastner et al.in the regions of positive and negative temperature.The microcanonical phase diagram of the Ising model shows a continuous phase transition at a negative temperature in energy and magnetization plane.However the phase diagram of the long-range model constructed by peaks of the microcanonical specific heat looks obviously different from the Ising chart.     

Nonlinear interaction of resonator photons with parametric magnon pairs

We condider the process of parametric resonance of magnons in magneto-ordered crystals in a microwave resonator. The nonlinear interaction of the resonator photons with the parametric magnon pairs is analysed theoretically, and the result expressed by the deviation frequencies relative to the pump frequency further demonstrates that the dynamics of resonator modes plays an important role once the pump power exceeds the threshold of parallel pumping.     

Discharge flow of granular particles through an orifice on a horizontal hopper:Effect of the hopper angle

We experimentally investigate the effect of the hopper angle on the flow rate of grains discharged from a twodimensional horizontal hopper on a conveyor belt.The flow rate grows with the hopper angle,and finally reaches a plateau.The curve feature appears to be similar for different orifice widths and conveyor belt-driven velocities.On the basis of an empirical law of flow rate for a flat-bottom hopper,we propose a modified equation to describe the relation between the flow rate and hopper angle,which is in a good agreement with the experimental results.     

Intruder Motion in Two-Dimensional Shaken Granular Beds

The dynamical behavior of an intruder immersed in a two-dimensional shaken granular bed is experimentally investigated. With two types of background particles, f-Г phase diagrams depicting the intruder＇s motion are measured and compared. It is found that even with the same size and density ratio of the intruder to the background particles, the intruder exhibits a distinct behavior at given vibrational conditions： rising behavior in one granular bed; sinking behavior in another granular bed. We slightly tune the size and density ratio to confirm the reliability of the experimental results. In addition, we examine the influences of interstitial air, convection and the initial position on the intruder＇s motion, speculating that the opposite motion could be traced to the material properties of the background particles.     

动态介质中的光折射现象研究

利用计算机模拟技术研究了动态介质中的光折射现象。将一定区域内带波浪的水假定为动态介质,以深度作为变量,利用几何光学原理及数值计算给出了介质深度不同时光强分布的规律,即相邻两明(暗)纹的中心间距随深度的变化而改变,明纹宽度和明纹平均亮度随深度的改变均呈现近似周期性变化而两者的变化趋势相反;另外,我们根据所得到的介质中光强分布的规律提出了一种测量水波速度的方法。