混合输入五杆机构的轨迹跟踪研究

混合输入五杆机构系统是一种新型的可控机构,采用恒速电机和伺服电机作为驱动元,两种类型的运动通过一个五杆机构复合后,可得到柔性输出运动.本文对混合输入五杆机构进行了逆运动学分析和动力学建模.为了实现对连续时变轨迹的跟踪任务,该系统采用计算力矩控制算法对伺服电机的运动进行控制.对混合输入五杆机构实现直线轨迹进行了仿真研究,结果表明了逆运动分析和控制算法的有效性,得到了比较好的轨迹跟踪效果.     

Fabrication of fullerene decorated by iron compound and its effect on the thermal stability and flammability for high-density polyethylene

Fullerene decorated by iron compound (C₆₀-Fe) is fabricated via solution reaction and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), wide-angle X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Upon incorporating C₆₀-Fe into high-density polyethylene (HDPE) matrix by melt blending, the thermal and thermo-oxidative stability of HDPE are considerably increased, the oxidative induction time (OIT) is dramatically extend. When the concentration of C₆₀-Fe reached 5 wt%, the onset degradation temperature in air increased from 352°C to 422°C, and the OIT dramatically delayed from 4.5 to 47.8 minutes. Moreover, from microscale combustion calorimetry (MCC), C₆₀-Fe can reduce the peak heat release rate (PHRR), heat release capacity (HRC), and total heat release (THR) values of the composites, all of which are very important parameters for evaluating the fire retardancy of a polymeric material.     

相转移催化合成N-烃基咔唑

研究了在聚乙二醇-400(PEG-400)、聚乙二醇-600(PEG-600)、聚乙二醇-800(PEG-800)、四丁基溴化铵(TBAB)、四丁基氯化铵(TBAC)、苄基三乙基氯化铵(TEBA)、十六烷基三甲基溴化铵(HTAB)、十六烷基三甲基氯化铵(HTAC)为相转移催化剂催化作用下,咔唑与溴代烃反应合成了8个N-烃基咔唑,并通过元素分析,IR,^1HNMR和MS对N-烃基咔唑的结构进行了表征。     

Bubble size modeling approach for the simulation of bubble columns

The constant bubble size modeling approach (CBSM) and variable bubble size modeling approach (VBSM) are frequently employed in Eulerian–Eulerian simulation of bubble columns. However, the accuracy of CBSM is limited while the computational efficiency of VBSM needs to be improved. This work aims to develop method for bubble size modeling which has high computational efficiency and accuracy in the simulation of bubble columns. The distribution of bubble sizes is represented by a series of discrete points, and the percentage of bubbles with various sizes at gas inlet is determined by the results of computational fluid dynamics (CFD)–population balance model (PBM) simulations, whereas the influence of bubble coalescence and breakup is neglected. The simulated results of a 0.15 m diameter bubble column suggest that the developed method has high computational speed and can achieve similar accuracy as CFD–PBM modeling. Furthermore, the convergence issues caused by solving population balance equations are addressed.     

Combination of double‐modified clay and polypropylene‐graft‐maleic anhydride for the simultaneously improved thermal and mechanical properties of polypropylene

Double‐modified montmorillonite (MMT) was first prepared by covalent modification of MMT with 3‐aminopropyltriethoxysilane and then intercalation modification by tributyl tetradecyl phosphonium ions. The obtained double‐modified MMT was melt compounded with polypropylene (PP) to obtain nanocomposites. The dispersion of the double‐modified MMT in PP was found to be greatly improved by the addition of PP‐graft‐maleic anhydride (PP‐g‐MA) as a “compatibilizer,” whose anhydride groups can react with the amino groups on the surface of the double‐modified MMT platelets and thus improve the dispersion of MMT in PP. Fourier transform infrared, X‐ray diffraction, transmission electron microscopy, thermogravimetric analysis, scanning electron microscopy, and tensile test were used to characterize the structure of the double‐modified MMT, morphology, and the thermal and mechanical properties of the nanocomposites. The results show that PP‐g‐MA promotes the formation of exfoliated/intercalated morphology and obviously increases the thermal properties, tensile strength, and Young's modulus of the PP/double‐modified MMT nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

集气管压力无级模糊控制系统

焦炉集气管压力是焦炉生产的重要工艺参数,以前存在集气管压力大幅波动、焦炉冒黄烟等现象。通过采用无级模糊控制技术有效解决了集气管的压力稳定问题,控制精度可达设定值±20Pa。     

Al2O3-SiC-C砖的研制及应用

以高铝矾土、碳化硅和鳞片石墨为主要原料,添加适量的抗氧化剂,采用酚醛树脂结合,分别研究了SiC和石墨的加入量对铁水预处理用Al2O3-SiC-C砖的常温性能以及高温强度、抗热震性和抗渣侵蚀等高温性能的影响,得出研制Al2O3-SiC-C砖的最佳试验配方(w)为:特级矾土中5~3、3~1、≤1、≤0.074 mm的分别占16%、30%、25%、4%,≤0.15 mm的石墨和≤0.074 mm的SiC分别为10%、12%,抗氧化剂3%,外加酚醛树脂4%。依此配方制成的Al2O3-SiC-C砖在某公司150 t KR铁水包上进行了试用,满足了钢厂的使用要求,且使用后的残砖表面较光滑,无明显砖缝或剥落现象。     

Ozawa方程处理PET非等温结晶动力学过程研究

采用Monte Carlo法计算机模拟在预先成核条件和不同降温速率下PET非等温结晶曲线,将模拟的结果用Ozawa方程及改进的Ozawa方程进行处理。结果表明,用Ozawa方程解析的Avrami指数与理论值相近,用改进的Ozawa方程可直接得到结晶速率常数,求出的线生长速率与理论值基本吻合。     

钒基负极材料在锂离子电容器中的应用

锂离子电容器一个电极采用电池型负极,一个采用电容型正极,因而兼具高能量密度、高功率密度的优点,有望成下一代新型储能器件.基于Faraday反应的电池型电极与电容型电极动力学不匹配是锂离子电容器的一个巨大挑战,因此研究者们发展了多种倍率性锂离子电池材料.在这些材料中,钒基材料以其成本低、比容量大、倍率性能优异等优点被认为...     

高产精氨酸的钝齿棒杆菌在高低供氧条件下的差异蛋白质组学初步研究

溶氧水平直接影响钝齿棒杆菌合成精氨酸产量的高低,运用双向电泳结合MALDI-TOF-MS及MS/MS质谱鉴定技术的方法对高低供氧条件下高产精氨酸的钝齿棒杆菌的胞内可溶性蛋白进行分离鉴定.结果表明,钝齿棒杆菌菌体蛋白的等电点主要分布在4-7的范围内,采用pH4-7的IPG胶条进行分离,得到了645±12个蛋白点.通过软件...