基于T-S模糊模型的球磨机料位测量研究

针对采用振动法测量球磨机料位时,振动信号和料位之间存在非线性和时变性,采用传统方法存在测量精度低、稳定性差的问题,提出基于T-S模糊模型的球磨机料位表示和测量的方法.首先利用减法聚类对振动信号的功率谱特征值进行模糊前件辨识,确定模糊概念和规则数;再用最小二乘估计辨识后件参数;最后,利用模糊推理方法实现球磨机料位的软测量.在小型球磨机上的试验结果验证了T-S模糊模型对球磨机料位测量的有效性,与传统方法相比,T-S模糊模型方法具有测量精度高、稳定性好的特点.     

介质温度对换热器胀接接头的影响分析

在换热器不同的工作介质温度下,选取液压胀接后的管板与接头为研究对象,建立了换热管与管板接头三维有限元模型,模拟分析了在10种介质温度下接头胀接后的密封性能和拉脱强度。计算结果表明,在工作状态下,残余接触压力随管程介质温度的升高先增加后减小,然后趋于稳定;拉脱力随温度升高先增大,然后趋于稳定。同常温相比,管程的介质温度升高使它的密封性能和拉脱强度都得到增强。     

Correlation investigation between contact approach speed of handheld metal rod and discharge parameters from charged human body

Characteristic measurement of contact discharge currents are made through a hand-held metal rod from charged human body. Correlation coefficients are obtained, through Statistic Package for Social Science （SPSS）, for various charge voltages, which is based on the effect test of electrode contact approach speeds on discharge current parameters of current peaks, maximum rising slope and spark lengths. Discharge parameters at charge voltage 300V are independent on approach speed. For charge voltages equal to and higher than 500V, the contact approach speed has strong positive correlation with discharge parameters of the peak current and the maximum rising slope, whereas has strong negative correlation with the spark length.     

板球系统的参数自调整反步控制

为解决系统初始值大范围变化,且控制量受到饱和特性约束的板球系统镇定控制问题,提出一种自动调整待设计参数的反步控制方法.分析了反步法偏差系统的平衡点特性;说明了反步法待设计参数与偏差系统动态间的关系;构造了Mamdani模糊逻辑,以自动调整反步法待设计参数;考虑了控制量受饱和特性限制而引入的约束条件,进而以遗传算法优化了模糊规则.仿真和实验结果均表明,自动调整待设计参数的反步控制方法降低了镇定控制中的位置偏差和位置超调.     

基于TMS320F2812的ABS轮角速度算法研究

在分析现有的轮速算法基础上,提出了轮速精度自适应算法,并利用TMS320F2812型DSP芯片进行系统开发,对各种算法进行比较,证明了该算法保持了高速时的精度及低速控制的实时性。     

H-POSS表面润湿性的分子动力学模拟

采用分子动力学模拟方法研究了水滴在多面体低聚倍半硅氧烷(H-POSS)固体表面的润湿性能,H-POSS分子和水分子分别采用COMPASS力场和SPC力场模型。模拟得到H-POSS基体密度为1.84g/cm~3,且X射线衍射模拟发现基体具有明显衍射峰,表现出晶体特性,说明COMPASS力场适用于H-POSS基体的构建与研究。H-POSS表面水接触角的模拟值为104.9°,具有疏水性能。通过直接水解法由三氯硅烷(HSiCl_3)实验合成出H-POSS样品,傅立叶红外表征(FT-IR)发现,在2260、1142和871cm~(-1)波数位置出现吸收峰,证实了所合成的样品为H-POSS。其表面水接触角的实验值为109.3°,与模拟值的相对误差仅为4%,说明分子动力学方法可应用于计算H-POSS材料表面润湿性。模拟结果还表明体系温度影响H-POSS材料的表面润湿性,增大体系温度,表面疏水性能降低。     

循环赛竞赛编排的算法实现

根据对抗性体育竞赛赛事编排的需要,结合球类等运动项目的组织规则和相关规定．运用数据库及网络技术,设计循环赛的比赛编排方法,同时赛事成绩信息通过通用运动会管理系统进行管理和发布,实现运动会的完全信息化管理。系统使大量繁琐的人工计算任务通过简单方便的操作便可以实现,大大减轻运动会组织人员的劳动强度,提高工作效率,保证数据的准确性、安全性。     

Estimating aerodynamic resistance of rough surfaces using angular reflectance

Current wind erosion and dust emission models neglect the heterogeneous nature of surface roughness and its geometric anisotropic effect on aerodynamic resistance, and over-estimate the erodible area by assuming it is not covered by roughness elements. We address these shortfalls with a new model which estimates aerodynamic roughness length (z₀) using angular reflectance of a rough surface. The new model is proportional to the frontal area index, directional, and represents the geometric anisotropy of z₀. The model explained most of the variation in two sets of wind tunnel measurements of aerodynamic roughness lengths (z₀). Field estimates of z₀ for varying wind directions were similar to predictions made by the new model. The model was used to estimate the erodible area exposed to abrasion by saltating particles. Vertically integrated horizontal flux (F_h) was calculated using the area not covered by non-erodible hemispheres; the approach embodied in dust emission models. Under the same model conditions, F_h estimated using the new model was up to 85% smaller than that using the conventional area not covered. These F_h simulations imply that wind erosion and dust emission models without geometric anisotropic sheltering of the surface, may considerably over-estimate F_h and hence the amount of dust emission. The new model provides a straightforward method to estimate aerodynamic resistance with the potential to improve the accuracy of wind erosion and dust emission models, a measure that can be retrieved using bi-directional reflectance models from angular satellite sensors, and an alternative to notoriously unreliable field estimates of z₀ and their extrapolations across landform scales.     

Simulation model of general human and humanoid motion

In the last decade we have witnessed a rapid growth of Humanoid Robotics, which has already constituted an autonomous research field. Humanoid robots (or simply humanoids) are expected in all situations of humans’ everyday life, “living” and cooperating with us. They will work in services, in homes, and hospitals, and they are even expected to get involved in sports. Hence, they will have to be capable of doing diverse kinds of tasks. This forces the researchers to develop an appropriate mathematical model to support simulation, design, and control of these systems. Another important fact is that today’s, and especially tomorrow’s, humanoid robots will be more and more humanlike in their shape and behavior. A dynamic model developed for an advanced humanoid robot may become a very useful tool for the dynamic analysis of human motion in different tasks (walking, running and jumping, manipulation, various sports, etc.). So, we derive a general model and talk about a human-and-humanoid simulation system. The basic idea is to start from a human/humanoid considered as a free spatial system (“flier”). Particular problems (walking, jumping, etc.) are then considered as different contact tasks – interaction between the flier and various objects (being either single bodies or separate dynamic systems).     

连续通电条件下触点接触电阻劣化的初步分析

电器长期通电后可使触点表面劣化,具体体现为接触电阻稳定增大、无规律增大、周期性变化、瞬时变化等电接触失效形式。本文以银镍触点材料为例,试验研究了接触压力、通电时间和通电电流对接触电阻的影响,并分析了接触电阻劣化失效的物理机制。