Microdroplet and Atomic Force Microscopy Probe Assisted Formation of Acidic Thin Layers for Silicon Nanostructuring

In this work, an aqueous acidic thin‐layer‐based strategy for fabricating nanostructures on silicon by using atomic force microscopy (AFM) nanolithography is presented. The approach involves the formation of microscale droplets via dilute hydrofluoride (DHF) etching, the conversion of the droplets to acidic thin layers by AFM‐probe scanning, and subsequent lithographic operations using a biased probe in the aqueous layers. By varying the concentration of the acidic DHF layers, the thin layers can facilitate the creation of both positive and negative patterns, such as oxide dots and Si pores, through anodic oxidation and dissolution. In particular, the anodic oxidation in the acidic media is associated with the field‐enhanced nonequilibrium dissociation of the weak electrolyte. The Si pore structure formation is related to the field‐assisted dissolution of anodic oxides and the Si substrate. The acidic‐layer‐based technique allows switching between different lithographic modes by changing the acidity of the DHF layers, and is complementary to bulk solution‐based and local meniscus‐based approaches in AFM nanolithography. In principle, this method can also be extended to other materials that have similar reactions with DHF.     

硅基氮化铝薄膜的AFM和XPS分析

在Si(111)基底上利用直流磁控溅射系统沉积氮化铝(AlN)薄膜,X-射线衍射分析薄膜结构和取向,原子力显微镜分析薄膜表面形貌,X-射线光电子能谱分析薄膜的元素化学价态和组分。结果表明,生长的AlN薄膜具有良好的(100)择优取向,其半峰宽为0.3°。薄膜表面粗糙度为0.23 nm,表面均方根粗糙度为0.30 nm,z轴方向最高突起约3.25 nm。薄膜表面组分为Al、N、O、C元素,其中C、O主要以物理吸附方式存在于薄膜表面,而Al、N元素的存在方式主要是Al—N化合物,深度剥蚀分析表明获得的AlN薄膜接近其化学计量比。     

V带传动中轴向压力的研究

介绍了摩托车上常用的V型皮带式无级变速器的工作原理.通过对V型皮带式无级变速器主动轮和从动轮的力学分析,建立了皮带传动的力学关系,推导了这种传动的设计公式,并指出了现有公式的不足,在公式中引入了一个新的参数———摩擦力方向角,给出了计算V带传动当量摩擦系数的准确公式.     

The effect of contact pad hardness on the fretting fatigue behaviour of AZ61 magnesium alloy

In the present study, the effect of hardness of contact material on fretting fatigue strength was experimentally investigated as a function of stress ratio. AZ61 magnesium alloy used in defense and transportation industries was used as the material for both the specimen and the contact pad. Two levels of hardness of contact material, 55.3 Vickers Hardness (HV) and 83.3 HV, were prepared by heat treatments. According to the results, with increasing hardness, the fretting fatigue strength decreased. The relative slip amplitude increased with increasing hardness, while the tangential force amplitude was not influenced by the hardness. It was speculated that because the local tangential stress at the contact edge increases with increasing hardness, the fretting fatigue strength decreases with increasing hardness.     

电连接器接触件应力场的数值分析与试验验证

利用ANSYS对某型号电连接器接触件应力场进行分析,以寻找应力变化规律.对接触件应力场分布特点、插孔形变、接触压力随温度升高的变化规律进行了仿真研究,并进行数据分析与接触压力的试验验证.结果表明:随着温度升高,插孔最大形变量增加,最大接触压力和接触压力区域都有所减少;尺寸较小的接触件插孔槽缝底部最大等效应力随温度升高增幅较大,交变载荷作用时易出现疲劳、破裂等,属产品失效薄弱点.通过分析得知最大等效应力值随温度上升而变化的趋势取决于温度软化效应和热应力增强作用的综合结果;仿真结果能较好地反映电连接器的工作应力状态,接触压力试验验证了有限元仿真方法的可行性.     

Force estimation via physical properties of air cushion for the control of a human-cooperative robot: basic experiments

For the control of a human-cooperative robot (HCR) using a soft material, we aim to verify, in this study, the usefulness of force estimation via physical properties of an air cushion. First, the physical model of the air cushion was represented by an air cylinder with a piston, which is subject to constraint by nonlinear elasticity. Second, the elastic properties of the air cushion were examined under the assumption that it can be formulated by a function of pneumatic pressure. The force applied to the air cushion was next estimated on the basis of the physical model, and the HCR was successfully controlled according to the estimated force.     

Modeling of a joint-type flexible endoscope based on elastic deformation and internal friction

Flexible endoscopes are widely used in minimally invasive surgical robot systems. Various kinematic models have been developed for describing the deformation of such endoscopes. For joint-type flexible endoscopes, most existing models neglect the effect of internal friction and cannot precisely show the shape.

In this paper, we propose a new nonlinear bending model. The rubber tube and metal net at each joint are approximated as a tube under elastic deformation and are assigned an equivalent bending stiffness. The internal friction force is also taken into account to build the moment balance equation at each joint. Groups of experiments were performed to validate the nonlinear model. The results closely confirm the model’s predictions. The model’s tip position error during the bending and unbending phases are 1.48?±?0.99?mm and 1.68?±?0.91?mm respectively; the bending angle errors are ?5.50?±?2.54° and 1.68?±?3.66°, respectively The model can also take account of the hysteresis effect of the bending, which is quite common for cable-driven flexible robots. Moreover, the model has good computational efficiency, making it suitable for real-time control.     

基于力反馈的手部康复训练装置研究进展

携带力反馈功能的装置进行训练已经成为手功能康复训练的重要手段.详细介绍了典型的用于手部康复训练的力反馈装置,通过对其优缺点进行比较,发现手部康复训练力反馈装置存在安全性要求高、重量较大、功能比较欠缺和实时性差的问题,并提出了相应的解决思路.最后展望了手部康复训练力反馈装置的发展趋势.     

试验台多通道加载系统的控制方法研究

试验台多通道加载系统是一种半实物仿真设备,能够在试验室条件下经济、有效地模拟飞机在飞行过程中所受到的舵面气动力矩载荷.通过分析加载系统多余力产生的机理,采用基于结构不变性原理的多余力补偿方法,加载系统可以有效地抑制舵机运动引起的干扰,实现较高的动态加载精度.