Nanotubes of mixed-valence, transition metal compounds synthesized by solution phase approach

A solution-phase approach to synthesize four kinds of mixed-valence, transition metal compounds nanotube is described. The approach is based on the self-assembly of siloxane sol. The resulted production of mixed-valence, transition metal compounds share a common structural characteristic of tubular geometrical morphology, at least for the ones we studied. The results demonstrate that the synthesis strategy can be a general route for preparation of compound nanotubes. In addition, the size control of nanotubular materials can be easily achieved through varying the ionic strength of solution. Based on the strategy, the diameters of ultrathin Ru-Fe nanotubes can be easily tuned between 100 nm and 800 nm.

Shape-gradient composite surfaces: Water droplets move uphill

The approach of water droplets self-running horizontally and uphill without any other forces was proposed by patterning the shape-gradient hydrophilic material (i.e., mica) to the hydrophobic matrix (i.e., wax or low-density polyethylene (LDPE)). The shape-gradient composite surface is the best one to drive water droplet self-running both at the high velocity and the maximal distance among four different geometrical mica/wax composite surfaces. The driving force for the water droplets self-running includes: (1) the great difference in wettability of surface materials, (2) the low contact angle hysteresis of surface materials, and (3) the space limitation of the shape-gradient transportation area. Furthermore, the average velocity and the maximal distance of the self-running were mainly determined by the gradient angle (alpha), the droplet volume, and the difference of the contact angle hysteresis. Theoretical analysis is in agreement with the experimental results.

Impedance study of (PEO)(10)LiClO4-Al2O3 composite polymer electrolyte with blocking electrodes

A composite solid polymer electrolyte (SPE) of (PEO)(10)LiClO4-Al2O3 was prepared and Pt and stainless steel(SS) blocking electrodes were used for an impedance study. It was found that the semicircle in the high frequency range and the straight line in the low frequency range depend upon different blocking electrodes and polarization potentials applied in the experiments. In the equivalent circuit. two constant phase elements (CPE) have been used instead of the pure geometrical and double layer capacitances. respectively. A theoretical line calculated from their estimated values has a good correlation with the experiment data. Moreover. the equivalent circuit also can be used to explain the impedance properties of Pt and stainless steel (SS) blocking electrodes both in the high and the low frequency ranges. (C) 2001 Elsevier Science Ltd. All rights reserved.

THEORY OF STEADY-STATE CURRENT AT MULTIPLE MICROCYLINDER ELECTRODES COUPLED WITH A PARALLEL PLANAR ELECTRODE

A novel device of multiple cylinder microelectrodes coupled with a parallel planar electrode was proposed. The feedback diffusion current at this device was studied using bilinear transformation of coordinates in the diffusion space, where lines of mass flux and equiconcentration are represented by orthogonal circular functions. The derived expression for the steady-state current shows that as the gap between cylindrical microelectrodes and planar electrode diminishes, greatly enhanced currents can be obtained with high signal-to-noise ratio. Other important geometrical parameters such as distance between adjacent microcylinders, cylinder radius, and number of microcylinders were also discussed in detail.

Dielectric responses of anisotropic graded granular composites having arbitrary inclusion shapes

The transformation field method (TFM) originated from Eshelby's transformation field theory is developed to estimate the effective permittivity of an anisotropic graded granular composite having inclusions of arbitrary shape and arbitrary anisotropic grading profile. The complicated boundary-value problem of the anisotropic graded composite is solved by introducing an appropriate transformation field within the whole composite region. As an example, the effective dielectric response for an anisotropic graded composite with inclusions having arbitrary geometrical shape and arbitrary grading profile is formulated. The validity of TFM is tested by comparing our results with the exact solution of an isotropic graded composite having inclusions with a power-law dielectric grading profile and good agreement is achieved in the dilute limit. Furthermore, it is found that the inclusion shape and the parameters of the grading profile can have profound effect on the effective permittivity at high concentrations of the inclusions. It is pointed out that TFM used in this paper can be further extended to investigate the effective elastic, thermal, and electroelastic properties of anisotropic graded granular composite materials.

基于眼固定安装方式的机器人定位系统

研发了基于眼固定安装方式的机器人定位系统,提出了一种方便有效的手眼标定方法。通过最小二乘法求解手眼坐标的变换关系,再根据工作台平面与摄像机成像模型的约束关系,求解出目标物体的三维位姿,并最终实现了机械手的精确定位。

应用于自动化生产线的视觉机器人系统

应用于融动化生产线基于眼固定安装方式的机器人定位系统,提出了一种方便有效的手眼标方法。通过最小二乘法求解手眼坐标的变换关系,再根据工作台平面与摄像机成像模型的约束关系,求解出目标物体的三维位姿,并最终实现丁机械手的精确定位。

机器人标定技术研究

机器人标定是离线编程技术实用化的关键技术之一 ,测量手段是制约其发展的一个重要因素 .本文提出了一种简单实用的测量方法 .同时建立了具有完备性、比例性、连续性的 RH6 - A型机器人的真实运动学模型 .并根据测量结果 ,成功地辨识出了机器人的几何结构参数 ,提高了机器人的绝对精度 .

基于视觉伺服的输电线巡检机器人抓线控制

巡检机器人在越障时,需要完成机器人手臂的准确抓线控制.结合输电线的几何特征和摄像机成像原理,提出了一种基于单摄像机的立体视觉方法来确定输电线的位置和姿态.基于该定位方法及视觉伺服理论,建立机械手抓线伺服控制模型.利用自行研制的巡检机器人进行了视觉伺服抓线实验;实验结果验证了该方法的有效性.

基于TOA的无线传感器网络自定位技术的研究

提出一种基于TOA(tim e of arrival)测距、利用节点之间的几何关系实现传感器网络中未知节点自定位的算法.该方法计算量小、算法简单且定位精度高.仿真实验证明了该方法的有效性.*

可重构星球探测机器人的运动学建模及轨迹规划

提出了可重构星球探测机器人的概念,对系统中子机器人的研究进行了重点论述.通过设计恰当的子机器人连杆坐标系,利用Denavit Hartenberg方法完成了子机器人的运动学建模,并直接给出了子机器人的运动学正解模型.由于使用单一的求解算法不能求出工作空间的封闭解,因此综合利用代数法、几何法原理及空间投影关系,结合子机器人的结构特殊性推导出了运动学逆解,从而得到了工作空间内的所有解.在此基础上,考虑结构间的约束关系,给出了子机器人的工作空间及轨迹规划方法.最后,使用OpenGL对设计的子机器人系统进行了运动学仿真实验,实验以末端操作器的直线运动为例,充分考虑空间几何的关系,其结果有效地证明了建模及轨迹规划的正确性.

一种7DOF冗余手臂构形的运动学与动力学特性研究

冗余度机构具有高度的灵活性和避障能力,利用冗余自由度可以改善仿人机器人手臂的运动性能。以实现人体手臂的运动特性和操作灵活性为目标,研制了一种7DOF冗余仿人机器人手臂,根据冗余手臂的机构学特点,研究了手臂的运动学和动力学性能,并在工作空间、肘部关节的自运动能力以及手臂自重引起的关节重力矩等方面与其它两种典型的冗余手臂构形进行了比较分析。

串并联数控机床的作业空间分析

鉴于并联机床普遍存在有效作业空间小、运动控制复杂和实用刚度还不理想等不足．采用了串并联混合式机床运动结构．针对所研究的4—4构型串并联机床,分析了影响作业性能的几何约束条件,采用基于位置逆解模型的极限边界数值搜索法,确定了机床作业空间,并通过数值仿真研究获得了机床运动参数和结构参数对作业空间的影响规律，为优化机床结构尺寸以获得尽可能大的有效作业空间奠定了基础。

基于约束的4自由度并联机床的可达工作空间分析

针对一种新型的4-DOF并联机构的结构特点,采用基于逆解计算的网格法对其工作空间求解的算法进行了详细的分析,并利用Matlab编制了相应的程序,以Matlab图的形式描绘了几种情况下的工作空间区域,并对此进行了分析。

大射电望远镜精调Stewart平台工作空间分析

针对大射电望远镜精调Stewart平台的五自由度运动特性,采用快速极坐标搜索法确定了五自由度大射电望远镜精调Stewart平台的工作空间.通过实例分析验证了所提出的工作空间分析方法的有效性.为大射电望远镜馈源轨迹跟踪实现和精调Stewart平台的设计奠定了坚实的基础.