Systematic robustness analysis of least squares mobile robot velocity estimation using a regular polygonal optical mouse array

This paper presents the robust velocity estimation of an omnidirectional mobile robot using a regular polygonal array of optical mice that are installed at the bottom of a mobile robot. First, the velocity kinematics from a mobile robot to an array of optical mice is derived, from which the least squares estimation of the mobile robot velocity is obtained as the simple average of the optical mouse velocity readings. Second, it is shown that a redundant number of optical mice contributes to the robustness of the least squares mobile robot velocity estimation against both measurement noises and partial malfunction of optical mice. Third, the sensitivity analysis of the least squares mobile robot velocity estimation to imprecise installation of optical mice is made, from which a practical method of optical mouse position calibration is devised. Finally, some experimental results using commercial optical mice are given to demonstrate the validity and performance of the proposed mobile robot velocity estimation. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

A new microsecond pulse-heating system to investigate thermophysical properties of solid and liquid metals

A new discharge system for resistive self-heating has been constructed for the measurement of accurate thermophysical properties. A constant-current pulse is used to heat metals over a time interval of 50 to 100 s, reaching temperatures up to the boiling point. New techniques have been developed to obtain sound speeds in the pulse-heated sample, emissivities, and vapor pressure. A new pyrometer allows the extension of the measured temperature range down to the melting point of copper.     

Speed-of-sound measurements in liquid and gaseous air

The speed of sound in air has been measured along isotherms for a standard air mixture (0.7811 N₂+0.2097 O₂+0.0092 Ar) in the gas and liquid phases at pressures to 14 MPa. A cylindrical resonator was used in the vapor and supercritical gas phases, and a time-of-flight system was used for measurements of the liquid phase. Data were obtained for the liquid phase at 90, 100, 110, 120, and 130 K. Data were taken at 110, 120, 130, 135, 140, 150, 200, and 300 K in the vapor and supercritical gas phases. These experimental results were compared to a predictive computer model, namely, AIRPROPS.     

旋转固体火箭发动机统一流场计算

为了进一步研究旋转对固体火箭发动机工作的影响,采用RSM湍流模型对内孔燃烧、内孔与端面同时燃烧管状装药旋转固体火箭发动机统一流场进行了仿真。采用UDF编程给出质量入口边界,获得了旋转条件下发动机内流场结构参数特点,并给予理论说明。计算结果表明,内孔燃烧装药发动机切向速度流场类似于典型的Rankine涡,端面和内孔同时燃烧装药发动机切向速度流场呈现出Rankine涡和由端面燃烧引起的强迫涡的复杂组合涡;在发动机前封头和喷管喉部涡核切向速度峰值非常大,使燃烧室前封头和喷管喉部工作环境显著恶化;旋转使发动机燃烧室压力沿径向逐渐增大,强迫涡附近的压力梯度远大于推进剂表面的压力梯度。     

Thermal transport behavior of van der Waals solids and liquids in the neighborhood of the solid-liquid phase transition

The thermal conductivity, , is one of the few transport coefficients which shows a relatively small change at the solid-liquid phase transition, and hence it is a property that can be used in comparing dynamic properties of both ordered and disordered systems. Although the discontinuity in can be accounted for largely by the difference in density, , of solid and liquid at the phase transition, its volume dependence is examined more closely. The thermal diffusivity, which is known to dominate the dynamic structure factor of liquid argon, has been determined around the phase transition also; the sound velocity has been considered in addition. The results are discussed and a comparison is made with these properties in solid and liquid benzene and cyclohexane.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

超声波检测混凝土结构抗冻性的方法研究

依据固体结构动弹模与表面波速度的关系，采用超声波检测混凝土冻融试件的动弹模，并与共振法测出的动弹模进行对比，总结出其内在相关规律，建立起预报混凝土动弹模的回归主程，由测得的波速计算出相应的动弹模，再利用动弹模之比评估出混凝土结构的抗冻性。初步试验和研究表明，此方法研究思路切实可行，符合混凝土冻融特性的基本变化规律，能够实现从度件测试向结构检测的发展，可供混凝土耐久性检测工程参考。     

多孔纤维型重整微反应器的等效电阻网络建模

针对应用于重整制氢微反应器的复杂多孔金属纤维载体（PFS）的流速场高效分析难题,建立载体中随机微通道的等效电阻网络分析模型. 基于复杂随机纤维结构的统计网络模型,将纤维载体中三维联通的随机微通道结构及与之相连的进出口腔简化为规则的网络通道结构.借鉴基尔霍夫定律,建立纤维载体的等效电阻网络模型,并确定求解方法. 纤维载体流速场实例分析的结果表明,基于等效电阻网络模型求解的纤维载体流速场与计算流体力学(CFD)方法的结果之间的皮尔森相关系数约为98%,且求解效率约为CFD方法的2.9×10⁴倍. 研究成果为多孔纤维型重整制氢微反应器的设计制造提供了新的支撑方案.     

变流场情景下基于鱼类游泳特性的上溯通道分析

水电开发对洄游性鱼类的生境造成了影响,预测目标鱼类洄游期的上溯通道可为修建过鱼设施提供依据,从而减缓其负面效应。本文选取虎渡溪航电工程的下游河段作为研究区域,将长薄鳅、白甲鱼、异鳔鳅鮀作为目标鱼类,针对几种目标鱼类的游泳能力对不同流速进行分区后,得出了适用于多种过鱼目标的流速适宜度曲线,然后对研究区域过鱼期的典型流量进行了数值模拟。根据流速适宜度曲线对研究区域的多种过鱼目标进行了流速适宜度评价,并由评价结果预测了满足多目标过鱼要求的上溯通道。结果表明：流速适宜度评价最优区域出现的位置随流量变化而有所不同,低流量运行条件下出现在主流区域,而高流量运行条件下出现在主流区域两侧;上溯的通道面积占总面积的比例也随流量变化而有所不同,低流量运行条件下的占比约为高流量运行条件下的3 ~ 4倍。根据预测通道特征,对鱼道的进口布置及电站运行调度提供了建议。该结果可为相关鱼类的保护工作提供依据。     

冲击荷载作用下热处理花岗岩动态力学特性研究

为研究冲击速度和热处理温度对黑云母花岗岩动态力学特性的影响,利用改进的霍普金森压杆系统对25~800 ℃共9个温度等级的热处理试样分别进行3种弹速下的冲击压缩试验。试验结果表明：随着冲击速度的增加,25~700 ℃热处理试样的应力—应变曲线由“Ⅱ型”转变为“Ⅰ型”,而800 ℃热处理试样均表现出“Ⅰ型”应力—应变曲线特征。同一温度热处理下试块的峰值应力、应变和平均应变均随动荷载的升高而增大。相同的冲击速度下,300 ℃热处理试样的动力学性能有所改善,500 ℃后试样的动力学性能开始逐渐劣化。同一温度热处理试样的破碎程度随冲击速度的增加而增加;相同冲击速度下,热处理试样的破碎程度随温度的升高先减弱后增强。     

铜基体超音速火焰喷涂碳化物涂层界面研究

使用扫描电子显微镜及透射电子显微镜，对铜基体超音速火焰喷涂（HVOF）碳化物涂层的形成过程，组织结构和界面形态进行了研究。结果表明，HVOF涂层界面显微组织非常复杂，存在纳米晶，非晶和大量位错孢，非晶是粘结相在喷涂中受热，骤冷形成的，而涂层中的纳米晶来自半熔碳化物的破碎。