RV减速器扭转刚度计算

扭转刚度是影响机器人运动精度、定位精度和重复定位精度的重要参数之一,本文通过对RV减速器内部齿轮副啮合刚度和各类型轴承刚度理论计算,提出了建立两个RV减速器虚拟样机,即在齿轮传动专业软件Romax中建立虚拟样机1,计算出系统变形引起的扭转刚度K1;同时在通用仿真动力学软件中建立虚拟样机2,计算出RV减速器回滞曲线,通过回滞曲线计算出扭转刚度K2,采用弹簧串联原理,计算了RV减速器扭转刚度K并通过试验验证了此方法的正确性。     

基于改进Renyi熵的运动目标图像提取仿真

运动目标图像提取有助于通过计算机视觉实现复杂变化背景下的图像细节分析,现有图像提取方法通常针对某一类图像作为研究对象,致使应用场合受到一定限制。针对运动目标图像的提取应用,提出了改进Renyi熵的运动目标图像提取方法。首先利用直方图对运动图像的YCbCr颜色概率进行估算,根据图像YCbCr颜色计算Renyi熵,然后设计相应的目标函数来确定阈值,并结合中值处理提高算法的抗噪声性能,最后对颜色的Y、Cb与Cr通道分割得到原始中心点,利用迭代处理更新中心点,并搜索出像素的边界阈值,从而实现运动目标图像的提取。通过仿真,分别从提取时间、计算熵值、以及目标图像识别率多个方面进行比较验证,证明了提出的改进Renyi熵的运动目标图像提取方法能够有效应对运动图像复杂多变的背景,提高了处理速度与提取准确度,具有较好的抗干扰能力。     

搅拌摩擦加工制备Al6061/SiC复合材料的耐蚀性研究

目的 利用搅拌摩擦加工技术制备纳米SiC铝基复合材料,研究经过纳米粒子的添加和FSP作用后,其耐腐蚀性能的变化及原因.方法 室温条件下,在3.5％NaCl溶液中,通过电化学阻抗谱和动电位极化曲线对试样的耐腐蚀性能进行检测分析.利用电子背散射衍射技术和透射电镜对3种试样的显微组织进行表征,研究耐腐蚀性能的变化机理.结果 经搅拌摩擦加工后,样品的阻抗值明显提高,动电位极化曲线测试结果显示,母材、FSP试样和复合材料试样的自腐蚀电位分别为–1.517、–1.338、–1.339 V,而腐蚀电流密度分别为0.48、0.11、0.12 mA/cm2.FSP加工试样的晶粒由平均晶粒尺寸为8.7μm左右的等轴晶粒构成,并且大部分析出相因高温作用发生溶解,而纳米SiC粒子的加入,使晶粒尺寸进一步降低至4.1μm左右.结论 所制备Al6061/SiC复合材料的耐腐蚀性能相较于母材明显改善,但弱于FSP试样.SiC和基体之间电位差的存在构成腐蚀微电池,降低材料的耐腐蚀性能,而晶界数量的增加造成点阵空位等缺陷增加,导致电荷转移的阻力增加,耐腐蚀性能得到改善.     

Heterostructure and phase engineering synergistically activated highly efficient alkaline hydrogen evolution in Mo2C/MoS2-rGO hybrids

Heterostructure and phase engineering are effective method to tune the electronic structure of MoS₂, which can activate and boost its intrinsic catalytic activity. Herein, the theoretical calculations reveal that the free energy of H1 adsorption (ΔG_H1) for Mo₂C (−0.65 eV) is lower than MoS₂ (2.05 eV), which is favorable for hydrogen adsorption. Inspired by the theoretical predictions, we develop a facile strategy to prepare nanostructured Mo₂C/MoS₂ dispersed on reduced graphene oxide (rGO) via a hydrothermal preparation and carburization reaction. Since the Mo₂C/MoS₂-rGO nanostructures with great deal of both MoS₂ and Mo₂C edges by heterostructure and phase engineering, which can induce massive active sites for HER on the surface of rGO, the intimate interfacial coupling effect between Mo₂C and MoS₂ can effectively improve the charge transfer rate. The Mo₂C/MoS₂-rGO catalyst exhibits exceptional HER properties, delivering a high turnover frequency (TOF) of 0.209 s⁻¹ at an overpotential of 200 mV in 0.1 M KOH. This work may open a new window for designing NPM electrocatalysts with highly efficient HER property based on earth-abundant materials.     

小型位移台的步进电机控制系统设计

针对光学位移台的运动控制要求,设计出一套基于单片机的步进电机驱动控制系统。单片机采用C8051F310,步进电机驱动器采用A3992,单片机通过RS485总线接收上位机命令,并通过SPI总线控制步进电机驱动器A3992的工作模式,通过软件程序实现了步进电机细分运动和S曲线运动,充分满足了光学位移台运行平稳、噪音低、定位精度高的控制要求。     

基于三维激光扫描的建筑模型可视化制作研究

为提升建筑模型制作精度,以三维激光扫描为技术背景,对建筑模型可视化制作方法展开研究.将三维激光扫描设备放置于少遮挡物且具有开阔视野的位置,经多次扫描取得多组重合的点云数据,通过变换坐标系间关系,完成点云数据拼接,对其去噪、光顺处理后,根据构成建筑物表面的若干个几何特征,提取截面边界与建筑特征结构,实现建筑模型可视化制作...     

超声振动钻削减摩机制研究与试验分析

在振动钻削加工原理的基础上建立振动钻削过程中平均摩擦力的数学模型,分析动载荷对平均摩擦力的影响规律。在超声振动钻削试验装置上对0Cr17Ni4Cu4Nb不锈钢进行了普通钻削和超声振动钻削试验,对比分析了孔壁表面粗糙度、钻头磨损形貌和切屑形状。结果表明:超声振动钻削能够减少平均摩擦力;通过观察加工后钻头与孔的表面形貌,超声振动钻削钻头磨损程度低,孔壁表面粗糙度值小,具有更好的断屑、排屑性能。     

Ni-doped Ba0.9Zr0.8Y0.2O3-δ as a methane dry reforming catalyst for direct CH4–CO2 solid oxide fuel cells

Fuel flexibility is one of the significant advantages of solid oxide fuel cells (SOFCs). The utilization of methane in SOFCs can not only reduce fuel costs, but also greatly expand its application scenarios, which is of great significance to the commercial development of SOFCs. However, when methane is directly used, Ni-based cermet anode suffers from coking, which seriously affects the durability of the cell. To alleviate the coking issue, a reforming layer outside the Ni-based anode-supporter was proposed in this study, and Ba_0.9(Zr_0.8Y_0.2)_1-xNi_xO_3-δ (BZYNi_x, x = 0.05, 0.1, 0.15 and 0.2) was used as reforming layer material. Among BZYNi_x catalysts, BZYNi_0.2 exhibited excellent catalytic activity toward dry reforming of methane, and methane conversion was as high as 85% at 750 °C. The excellent catalytic durability and coking-resistance of BZYNi_0.2 were also confirmed. When BZYNi_0.2 reforming layer was applied, the single cell fueled with CH₄–CO₂ fuel showed significantly improved electrochemical performance, durability and coking-resistance. The utilization of BZYNi_0.2 reforming layer provides guidance for solving the coking issue of SOFC cermet anodes when fueled with hydrocarbon.     

Steam exfoliation of graphitic carbon nitride as efficient route toward metal-free electrode materials for hydrogen production

This study demonstrates the potential of obtaining nanostructured materials based on g-C₃N₄ with a high specific surface area for use as efficient electrode materials for hydrogen production. The study uses a novel method of g-C₃N₄ exfoliation that increases the specific surface area of the starting material by a factor of three. Nanocrystalline g-C₃N₄ is obtained through the thermolysis of urea and treated with steam in a specified temperature range. The resulting series is analyzed using a range of physicochemical methods to determine the optimal temperature for steam exfoliation. Catalytic electrochemical tests are carried out in the electrolytic reforming of ethanol. It has been demonstrated that steam exfoliation can boost the rate of electrocatalytic reforming by 1.3 times while decreasing the amount of hydrogen evolution overpotential. The results of this study demonstrate the potential for the use of steam exfoliation as an effective method for obtaining high-performing electrode materials for hydrogen production.