前轮操舵驱动移动机器人前后轮横滑刚度测量

通过对移动机器人进行平面运动动力学及运动学分析，建立平面运动移动机器人稳态圆运动动力学方程组；结合前轮驱动电机编码器、舵电机编码器以及机架陀螺仪分别采集到的前轮移动速度、舵角和机器人本体偏摆角速度，利用牛顿-拉夫森方法对动力学方程组进行求解，得到机器人前后轮的横滑刚度。研究结果为轮式移动机器人横滑特性及动力学研究提供了一种简单有效的手段，对路径跟踪研究也具有一定的参考价值。     

Synthesis and performance of novel magnetically separable nanospheres of titanium dioxide photocatalyst with egg-like structure

A magnetically separable photocatalyst TiO(2)/SiO(2)/NiFe(2)O(4) (TSN) nanosphere with egg-like structure was prepared by a unique process that combined a liquid catalytic phase transformation method, reverse micelle technique and chemical precipitation means. The prepared photocatalyst shows high photocatalytic activity for the degradation of methyl orange in water. The magnetic property measurements indicate that the photocatalyst possesses a superparamagnetic nature. It can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for wastewater treatment. A transmission electron microscope (TEM) and an x-ray diffractometer (XRD) were used to characterize the structure of the TSN photocatalyst. The results indicate that nickel ferrite core nanoparticles were completely encapsulated into monodisperse silica nanospheres as carrier, and titania nanoparticle aggregates were coated onto the surface of SN nanospheres, forming an imperfect TiO(2) shell for photocatalysis. The SiO(2) layer between the NiFe(2)O(4) core and the TiO(2) shell effectively prevents the injection of charges from TiO(2) particles to NiFe(2)O(4), which gives rise to an increase in photocatalytic activity. Moreover, the recycled TSN exhibits good repeatability of the photocatalytic activity.     

An improved numerical method for predicting intermetallic layer thickness developed during the formation of solder joints on Cu substrates

An improved numerical method has been developed for calculating the thickness of intermetallic layers formed between Cu substrates and solders during the soldering process. The improved method takes into account intermetallic dissolution during heating and intermetallic precipitation during cooling and requires as input (1) the temperature-time profile for the soldering process, (2) the experimentally determined isothermal growth parameters for the growth of the intermetallic layer into Cu saturated molten solder, (3) the experimentally determined Nernst-Brunner parameters for the dissolution of Cu into molten solder, (4) the experimentally determined solubility of Cu in molten solder and (5) assumptions about the thickness of the boundary layer in the liquid ahead of the growing intermetallic. Calculations show that the improved method predicts intermetallic growth between Cu substrates and 96.5Sn-3.5Ag solder during reflow soldering better than a previously developed method, which did not take into account dissolution during heating and precipitation during cooling. Calculations further show that dissolution has a significant effect on growth, while precipitation does not.     

无功就地补偿在晋城市自来水公司的应用

0前言电费在供水企业的生产成本中占相当大的比重。各地都有着各自不同的生产条件,除合理选择机泵型号外,积极响应国家的电价政策,提高功率因数,降低电费开支显得尤为重要。用户用电功率因数的高低,对电力系统发、供、     

CMAC改进算法在电动负载模拟器的应用

在电动负载模拟器的控制系统设计中,其参数优化一般需要大量试验.根据负载模拟器的工作原理建立了伺服电机的数学模型,在分析CMAC神经网络控制结构的基础上,引入了更新系数和补偿环节,提出了一种基于CMAC神经网络的改进算法.对各控制参数进行了寻优,获得了参数的选择域.通过对系统的数字仿真表明,该方法可稳定地跟踪非线性输入,...     

Effect of HEA/Al composite interlayer on microstructure and mechanical property of Ti/Mg bimetal composite by solid-liquid compound casting

In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer.The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis.Results indicate that the sluggish diffusion effect of HEA can ...     

阻尼多楔带传动系统建模及带滑移控制分析

考虑多楔带的阻尼特性和带在带轮上的蠕变对带张力的影响,建立了阻尼多楔带传动系统旋转运动模型,给出了带张力和各带轮的旋转角位移的数值计算方法,并引入了滑移因子预测滑移现象的发生.分析研究多楔带阻尼对系统运动特性的影响,及当多楔带传动系统结构参数确定时,张紧器预载荷、安装角对带滑移的影响.建立的阻尼多楔带传动系统旋转运动模型和数值求解方法为带传动系统的研究提供了理论依据,对带滑移控制的分析为带传动系统的设计提供了参考.     

驾驶过程中手机使用的补偿式行为

驾驶员在驾车过程中使用手机会造成驾驶分心,研究驾驶中的补偿行为有助于降低驾驶分心造成的危害。通过模拟驾驶探究驾驶行为和生理指标在是否使用手机、不同路段复杂程度、不同驾驶员类型中的差异,从而使驾驶员注意到驾驶中使用手机的危害并及时采取措施,弥补驾驶分心带来的危害。研究结果表明,使用手机主效应在各项指标中均呈现显著影响(P<0.001),驾驶员类型主效应在阅读短信行为中的踩刹车持续时间上存在显著影响(P<0.01),使用手机与驾驶员类型交互作用在接听电话行为的心率、阅读短信行为中的平均速度、踩刹车持续时间和心率上存在显著影响(P<0.05)。比起接听免提电话,阅读短信时采取补偿行为的幅度更大(P<0.05);驾驶员比学员采取补偿行为的幅度更大(P<0.05)。     

套管膨胀过程中膨胀锥锥角对驱动力的影响

采用有限元方法模拟套管膨胀过程,求解了膨胀锥锥角不同时的液压驱动力,并分析了所需驱动力的大小与膨胀锥锥角的关系。结果表明,套管膨胀过程中膨胀锥存在一个最优锥角,在此锥角下膨胀套管所需的驱动力最小。在小于最优锥角范围内,驱动力随锥角的增大快速降低,在大于锥角范围内,驱动力随锥角的增大有增大的趋势。对于结构参数相同而材料钢级不同的套管,最优膨胀锥锥角较接近,与最优锥角对应的最小驱动力也较接近。