穿地龙机器人轨迹规划及其运动过程仿真研究

以建立的"穿地龙"机器人轨迹规划数学模型为计算机仿真模型,对"穿地龙"机器人工作时的运动过程进行了计算机仿真研究,编制了大量仿真程序,获得了较好的仿真结果.通过运行仿真程序,可以在计算机上直接观察到"穿地龙"机器人运动的过程.进行"穿地龙"机器人运动学、动力学仿真,该研究工作为改进"穿地龙"机器人试验样机设计,并为设计"穿地龙"机器人工作用机和进行"穿地龙"机器人的应用分析提供了一定的条件.     

一类大规模系统神经网络自适应控制方案设计

针对一类大规模非线性机械系统,如自动化高速公路汽车空位调节和连续搅拌反应釜等系统,设计了一套基于前向神经网络的分散自适应控制方案以实现对其有效控制．作为直接自适应控制器,神经网络被用于逼近未知函数,所设计的两个鲁棒控制项分别用于消除互连效应和干扰项．系统稳定性得到严格证明,通过仿真进一步验证了方案的有效性．     

6—10kV电网谐振过电压的分析

本文通过理论分析,对6-10kV电网发生谐振的条件和危害性作出了估量,它可以对电网的设计和事故分析提供理论依据。     

深腔圆锥动静压混合轴承润滑特性

为了更加准确探求深腔圆锥动静压轴承润滑特性,考虑润滑油膜紊流、热效应及轴向速度等因素,推导极坐标系下的广义雷诺方程、能量控制方程及其相关表达式,采用有限差分法对方程进行离散,利用帕坦卡正系数法则对离散化方程系数及常数项进行处理,数值分析油膜的三维压力场和温度场,试验研究静压浮起和动压润滑特性.结果表明:帕坦卡正系数法则可以有效地解决诸如油腔边缘存在"逆流"等因素而导致温度场不易收敛问题,在高速大偏心率情况下,油膜温升较高,应考虑温度对轴承性能的影响.流量与供油压力成正比关系,而与转速基本无关.随着转速增加动压效应增强,轻载时轴承在小偏心率下工作.深腔圆锥动静压轴承具有良好的静压浮起和动压润滑特性,理论计算值与试验结果一致,证明理论的正确性,为下一步转子动力学的理论分析打下基础.     

平面子孔径拼接的面旋转误差

在按某一基准面进行拼接的过程中,存在着只与测量误差相关而与子孔径面形无关的误差,将其命名为面旋转误差.本文对比分析了顺序拼接和误差均化拼接中存在的面旋转误差的情况,讨论了面旋转误差对拼接的影响.给出了对抑制面旋转误差的基本想法,并论述了其可行性.     

Experimental and numerical study on aerodynamic noise of outdoor unit of room air conditioner with different grilles

The aerodynamic and aeroacoustic performances of outdoor unit with two different types of grille have been investigated in present study. Experimental results indicate that the grille sharp will affect the flow rate and increase broadband noise level of outdoor unit. Based on noise generation mechanism and CFD simulation, vortex shedding noise model and inlet turbulence noise model are adopted to predict the broadband noise level of outdoor unit. When vortex shedding noise is concerned, the wake parameters should be calculated at 3 mm downstream of grille to achieve good accuracy. Inlet turbulence noise is generated from the interaction between blade wake and the grille, and plays less important role in present outdoor unit configuration. In comparison with experimental results, it is shown that the broadband noise prediction method could provide reasonable accuracy and the error between prediction and experiment is less than 1 dBA.     

Centrifugal pump for superfluid helium

This Paper summarizes and correlates the liquid helium pump data obtained previously in two separate test programs. In normal helium the second set of data shows a large performance improvement over the first set as a result of changes in measurement methods and in the pump itself. Peak pump efficiencies of 46% were measured. The pump appeared to perform approximately the same in He II as in He I; however, the He II data are not adequate for system design or analyses. Therefore, a new pump test program is planned to test the improved version of the pump in an apparatus designed specifically for He II.     

Measurement of the thermal properties of TiFe0.85Mn0.15 and its hydrides

A high vacuum/high pressure measuring apparatus for the study of equilibrium thermophysical properties, heat transfer parameters and dynamic reaction thermal response of hydrogen storage alloys has been constructed. The absolute thermal conductivity of massive hydridable TiFe_0.85Mn_0.15 alloy has been determined, as well as the effective thermal conductivities of identical particulated material in both unhydrided and hydrided form using the steady-state plate method.The effective conductivity of powders with particle sizes between 0.075 and 0.425 mm is found to be strongly temperature- and pressure-dependent, with values ranging from 0.1 W m⁻¹ K⁻¹ in high vacuum of 10⁻³ Pa, to 1.5 W m⁻¹ K⁻¹ at high He or H₂ pressures up to 5.5 MPa. Hydriding of the powders does not significantly change the effective conductivity, whereas packing density, contact pressure and particle size does so. Massive TiFe_0.85Mn_0.15 has a surprisingly high absolute thermal conductivity of 77.2 W m⁻¹ K⁻¹, which is temperature independent in the range from 0–150°C.     

Flow of microorganisms in a hospital stair shaft — Full-scale measurements and mathematical model

Measurements of air flow and microorganism concentration have been made in the stair shafts of a hospital, using a diving bell-type of pressure-recording instrument, and a sampler for the microorganisms, respectively. Results of experiments were used to calculate the flow rate of microorganisms between the floors of the hospital. A mathematical model based on simplified transport equations is proposed, which would allow the prediction of the flow field and the distribution of microorganisms in the stair shaft. Comparisons between measurements and numerical calculations indicate that the mathematical model is able to predict the global flow field, qualitatively. The application of the numerical method can help to reduce the experimental work, as well as to investigate the complex exchange mechanisms of microorganisms.