ADJUSTABLE LEVER-TYPE ACTIVE TUNED MASS DAMPER： A NEW ATMD MODEL

The Adjustable Lever-Type Active Tuned Mass Damper (ALT-ATMD) is proposed to gain a control system with high effectiveness, which may cope with large static stretching of the spring. The main objective of this paper is to assess the performance of the ALT-ATMD (including the ALT-ATMD stroke) through numerical analyses using the formulated dynamic magnification factors of the ALT-ATMD structure system. The results indicate that the static stretching of the spring in the ALT-ATMD with the actuator set at the mass block may be freely adjusted in accordance with the practical requirements by moving the mass block, while approximately maintaining the same optimum resultant damping ratio, effectiveness, and stroke.     

两个值得重视的基本概念

本文指出某些有代表性的物理教材中功的定义式与准静态过程表述不妥之处，从教学的角度提出了改进的建议     

由电阻率的准静态测量研究薄膜晶粒的生长动力学

提出一种用薄膜电阻率的准静态测量来进行薄膜晶粒生长动力学研究的方法。在超高真空系统中用直流溅射制备Pd膜,然后测量不同温度下Pd膜电阻率与退火时间的关系。利用二流体模型推算出对应晶粒尺寸大小的变化,并和TEM结果进行比较。在此基础上进一步分析了退火温度对薄膜中晶粒尺寸变化所起的作用,拟合出晶粒的生长曲线。实验结果表明晶粒长大是一种热激活生长过程,激活能约为0.53eV。 关键词：     

服务水平约束下双需求类静态配给策略

考虑一个周期盘点、无限期、缺货回补、双需求类的库存系统,其中高优先级需求的目标服务水平较高。系统采用基准库存策略补充库存,依据静态配给策略分配库存,即优先满足高优先级需求,仅当持有库存水平不低于固定配给阈值时满足低优先级需求。优化目标是在服务水平约束下最小化期望库存持有量。为提升计算效率,引入“预留库存假设”,即允许通过提高低优先级需求缺货水平的方式补充库存,使得期末持有库存水平不低于本期高优先级需求缺货水平与固定配给阈值之和。基于预留库存假设,给出两类需求服务水平和期望库存持有量的解析表达式,证明上述绩效指标关于控制参数的单调性,刻画满足服务水平约束的控制参数可行域,得到原系统最优控制参数的近似求解算法。算例分析表明,基于预留库存假设的绩效衡量方法和参数求解算法准确性好且计算效率高。     

Late-Time Evolution of the Phantom Scalar Perturbation in the Background of a Spherically Symmetric Static Black Hole

The late-time evolution of the phantom scalar perturbation is investigated in the spacetime of a four-dimensionai spherically symmetric static black hole. It is revealed that the asymptotic tail of the phantom scalar field is dominated by the growth behavior t-（l＋3/2）eμt, which depends on the multipole moment l and the field moss but is independent of the mass M and charge Q of the black hole. This growth behavior is in strong contrast to the decaying tall of the usual massive scalar perturbation and shows that the external phantom scalar perturbation is unstable in the spherically symmetric static black hole spacetime.     

Active Mixing in a Microchannel

We investigate a minute magneto hydro-dynamic mixer with relatively rapid mixing enhancement experimentally and analytically. The mixer is fabricated with brass and polymethyl methacrylate （PMMA） layers. A secondary flow is generated by using the Lorentz force in the fluids. The efficiency of mixing is greatly improved due to the large increase of the contact area between two mixing fluids. The micro particle image velocimetry technique is employed to measure the fluid flow characteristics in the micro-channel. Numerical simulation is performed based on the theoretical model of the computational fluid dynamics and the electromagnetic field theory. The experimental results are in good agreement with the numerical results, which indicates that the mixing area is enlarged by the driving of Lorentz force and the mixing can be enhanced.     

加速度计标定中静态半径误差项的消除技术

基于离心机对线加速度计进行标定时,首先需确定加速度计有效质量中心到离心机旋转中心的距离,即静态半径。目前相关的确定方法较为繁琐,实际中难以操作。提出一种直接消除双离心机静态半径误差的测试分析方法,该方法基于加速度计在双离心机上测试标定时在正向输入和反向输入条件下其安装位置误差的对称性,将安装位置误差项引入加速度计的静态模型方程中。通过对模型方程的处理,消除了结果数据中的安装误差项,获得了不含安装误差项的加速度计标度因数计算方法,并且基于所获得的标度因数,可以计算获得安装位置误差值。对比测试验证结果表明,同个加速度计在正常安装((35)R/R_1约0.37%)和人为增大安装位置误差((35)R/R_1约5.22%)的情况下,经过消除安装位置误差项的处理,所获得的标度因数仅相差约0.036%,证明了该方法的有效性。该方法有效消除了安装位置误差对标度因数的影响,提高了标定精度,同时简化了加速度计的标定步骤。     

两级分块结构化网格在SK型静态混合器中的应用

给出一种适用于SK型静态混合器流场数值模拟的两级分块结构化网格划分方案和分块圆弧区点的极坐标方程。与常用的非结构四面体网格划分对比,两种方法划分网格数量相近时,两级分块结构化网格达到的迭代精度高于非结构化网格一个等级,而非结构化网格收敛所用时间约为结构化网格收敛所用时间的1.25倍;运用控制体积容积变化值对两种方法划分网格进行质量评估,结构化网格划分方法接近99%网格质量指标在1.0~2.0范围内,而非结构化网格仅接近60%网格质量指标在1.0~2.0范围内。通过实验测量对两种方法划分网格数值模拟结果进行对比验证,结构化网格计算结果与实验值更为接近,表明其可行性和准确性均优于非结构四面体网格划分。     

静态真空对超声喷流气体团簇制备的实验研究

研究了靶室静态真空对超声喷流气体团簇产生和制备的影响.通过瑞利散射方法测量了不同静态真空度下超声喷流氩团簇的尺度和密度参数,发现在喷嘴出口附近团簇尺度和密度受静态真空度的影响较小;在距离喷嘴较远处,氩气团簇存在同氢气团簇类似的自限制效应,验证了自限制效应在团簇制备、输运过程中的重要作用.该结果对于建造基于激光聚变原理的桌面中子源具有较大的参考意义,可据此简化真空装置以降低运行和维护成本.