角动量守恒演示仪的设计与实践

1设计演示仪的构想角动量守恒演示仪常用于物理实验教学,但是多数学校配备的都是操作过程复杂的全机械结构,并且实验现象比较单一.如果将此类仪器电动化,并引进多方面的对比,则不仅可使演示的效果愈加明显,增加趣味性,更使得实验仪器具有了"综合性、     

定子表面织构对超声电机性能的影响

针对超声电机摩擦材料磨损严重和温升高的问题，采用在定子表面加工微织构的方法，提高了电机机械特性并降低了摩擦材料磨损. 首先，用显微镜测量超声电机定子表面摩擦材料黏着区域，设计出三种不同密度的凹坑织构，采用激光的方法加工在定子表面；然后，测试超声电机负载特性、效率特性和温升特性并观察定子表面. 结果表明:3-凹坑织构定子电机空载转速最高，相比光滑定子电机高出12.1%，5-凹坑织构定子电机堵转转矩和最大效率最高，分别高于光滑定子电机13.04%和17.1%，同时电机的温升也有所降低. 通过观察定子表面发现，凹坑织构有大幅降低摩擦材料黏着的作用，这种作用可以增加电机接触界面能量转换效率，提高了电机的性能并降低了摩擦材料的磨损.      

振动机械起动过程中的迟滞共振原因分析

振动机械在起动过程中，有时会出现一种特殊的共振现象─—迟滞共振．本文通过解析分析和数值算法解释了产生该现象的原因．     

Two sample applications of a classical isoperimetric problem of the calculus of variations to fluid mechanical problems in fluidization and spouting

This paper is devoted to outlining precisely the basic mathematics of a classical isoperimetric problem of the calculus of variations and showing how significant fluid mechanical problems in fluidization and spouting can be addressed using this approach.     

Multi-Phase Flow and Heat Transfer of a Micro-Pump Thermally Driven by a Multi-Output Pulse Laser

We present an experimental study of multi-phase flow and heat transfer in a micro-tube induced by a multi-output pulse laser. Extensive flow and heat transfer measurements and visualization experiments have been carried out to characterize the micro-pump behaviour under various conditions. The experiments reveal extremely unsteady and complex flow patterns in the micro tube with the flow closely related with generation and collapse of bubbles.It is found that the flow rates are controlled by the heating and condensation conditions within the tube. The laser pulse duration, pulse interval and output-power as well as the tube diameter all show a strong influence on the flow rate of the micro-pump. This study provides a basis for the design of thermally-driven micro-pump induced by a pulsed laser beam.     

机械力化学改性硅酸盐矿物的FTIR研究

利用气流磨所产生的超音速气流作为机械力，分别对层状硅酸盐矿物滑石、绢云母、高岭土和链状硅酸盐矿折硅灰石与硬脂酸进行超细粉碎－表面改性，应用FTIR法进行研究。     

Mechanical Properties of Breast Cancer Cell Membrane Studied with Optical Tweezers

Membrane tethers are extracted from breast cancer cells using a force generated by an optical trap. It is experimentally obtained that the radius of tether is about 0.1μm and the static tether force is about 8.5 pN. Calculations based on the experimental measurements give a bending modulus for the tether of 1.35 x 10^-19 N.m and a surface membrane tension of 6.76 x 10^-6 N/m in the breast cancer cell. The treatment with cytochalasin D results in the decreasing bending modulus and decreasing apparent surface tension. When the membrane protein caveolin is over-expressed, similar cases occur in bending modulus and apparent surface tension. In addition, the viscous resistance coefficient of the membrane is calculated to be 1.15pN.s/μm according to the dynamic tether forces obtained under different pulling velocities.     

机械动态系统混沌状态特征与判据应用研究

本基于混沌动力学与分行几何学理论分析，通过研究机械动态系统的Lypunov指数、关联维数、Kolmogorov熵以及它们对系统吸引子特征的描述，结合递次振幅图方法，提供了一种证明系统状态混沌性的方法。并以变速箱中齿轮运行状态为例，通过对其动态信号混沌特征量的研究，证实了该系统混沌性，进而得出对系统故障进行进一步混沌预测的可行性。     

王徵(1571～1644)——机械发明家,中西科技文化交流的先驱,中国历史上著书介绍西方力学的第一人

1 王 徵生平 王徵字良甫,又字葵心,自号了一道人或了一子,支离叟.陕西省泾阳县龙泉乡王家堡人.生于1571年(明穆宗隆庆五年).幼随舅父张鉴(奉议大夫)游学,万历廿二年(1594年)举人,时年廿四岁.     

用现代方法制造光学元件

次波长光学元件 ( SOEs)通常是用某种平版印刷术制造的 (虽然有时采用光刻法 ) ,这类光学元件含有一维或二维形式的阵列结构 ,这些阵列改变折射或反射光而不产生零以外的衍射级。这种次波长的光学元件具有 2 0 0 nm级的周期率 ,偏振能达到 97%的透射率或反射率 ,并具有大于40 d B的透射衰减和大于 2 0 d B反射衰减。这种元件的标准尺寸虽然只有 1 .4× 1 .4mm,但还能制成约 1 0mm大小尺寸。目前它主要用在光纤通信领域。这种次波长光学元件是将一种模型压入衬底上的一层光致抗蚀剂中而制成的。采用反应离子蚀刻工艺在衬底上或淀积在衬底上…