级联H桥整流器的双调制轨迹控制研究

级联H桥多电平整流器的直流侧电容电压平衡问题是影响变换器整体性能的主要问题之一.从安全工作区和负载功率分配角度讨论了该问题产生的原因,并给出了级联H桥多电平整流器直流侧电容电压平衡的边界条件,在此基础上提出了双调制轨迹法,并给出了双调制轨迹法的逻辑代数描述及通用算法,使其可扩展到多H桥级联的场合.通过使用提出的控制策略,级联H桥变换器交流侧电压合成点可被强制落在边界条件上,从而可在更大的负载不平衡区间上实现直流侧电容电压的平衡.仿真结果验证了所提控制策略的有效性.     

基于两级插补机制的NURBS曲线插补器研究

针对非均匀有理B样条（non-uniform rational B-spline,NURBS）曲线高速高精加工过程中计算负载高的问题,提出一种基于两级插补机制的NURBS曲线插补器方案,在主控端执行第一级插补,完成曲线预处理等粗插补工作;在运动控制端执行第二级插补,完成加减速及实时位置输出等精插补工作。同时,设计并开发基于ARM-FPGA架构的实验平台,可用于两级插补器的实验验证,具有一定的现实参考意义。     

测井曲线在潘一矿13-1煤层识别构造煤中的应用

为预测未揭露区煤体结构,根据钻孔测井曲线信息,结合视电阻率电位曲线与伽马伽马曲线对煤层内不同结构分层物性差异所反映的形态特征,通过对煤层内部的各分层之间的比较、煤层与邻近钻孔中同一煤层的比较和煤层与钻孔内的上、下煤层之间进行比较绘制出煤层结构柱状图。又以矿井煤层底板等高线图作为底图绘制构造煤平面分布图,判识煤层内部的构造煤分布。     

X70和16Mn钢土壤腐蚀行为比较I电位和平均腐蚀速度

通过研究国内常用的X70和16Mn 2种管道钢在土壤浸出液中的电位-时间曲线，并根据失重试验和极化曲线，比较它们的平均腐蚀速度.结果表明，16Mn钢腐蚀电位比X70钢稍负约20 mV，其平均腐蚀速度明显高于X70钢；X70钢的腐蚀产物膜具有短期保护性.     

Adaptive interpolation scheme for NURBS curves with the integration of machining dynamics

This paper develops a comprehensive interpolation scheme for non-uniform rational B-spline (NURBS) curves, which does not only simultaneously meet the requirements of both constant feedrate and chord accuracy, but also real-time integrates machining dynamics in the interpolation stage. Although the existing work in this regard has realized the importance to simultaneously consider chord error and machining dynamics, none has really incorporated these in one complete interpolation scheme. In this paper, machining dynamics is considered for three aspects: sharp corners or feedrate sensitive corners on the curves, components with high frequencies or frequencies matching machine natural ones and high jerks. A look-ahead module was developed for detecting and adaptively adjusting the feedrate at the sharp corners. By Fast Fourier Transform (FFT) analysis with a moving window in the interpolation stage identified were some special frequency components such as those containing high frequencies or with frequencies matching machine natural ones. Then, the notch filtering or time spacing method was used to eliminate these components. To more completely reduce feedrate and acceleration fluctuations, the jerk-limited algorithm was also developed. Finally, the interpolated feedrate was further smoothened with B-spline fitting method and the NURBS curves were re-interpolated with the smoothened feedrate. During the interpolation, the chord error was repeatedly checked and confined in the prescribed tolerance. Two NURBS curves were used as examples to test the feasibility of the developed interpolation scheme.     

基于产品件展开后毛坯网格的边界外延方法

产品件用一步逆成形初始场预示方法展开得到的坯料形状,没有考虑成形过程中除零件本身以外所需要的板料面积,因此,需要对展开后的坯料网格再进行一定尺寸的延展,才能保证得到最终坯料尺寸的正确性。文章提出了一种将离散数据连续化后,利用非均匀有理B样条(NURBS)的几何性能完成延展再离散成网格数据的方法,能够很好地预示出满足冲压需要的最终坯料形状。这种方法具有计算效率高、优化效果好等优点。     

应用Visual Basic实现点焊电流和压力的实时监测

动态多参数实时监测是电阻点焊质量在线评估的一种有效方法。采用Visual Basic6.0语言编程．通过80C196KB和PC机之间的串行通信，实现了对焊接电流和电极压力的实时检测，联机试验所生成的波形图实时反映了三相次级整流点焊的动态焊接过程以及曲线变化趋势与影响因素之间的对应关系，为点焊质量多参数监控奠定了基础。     

The isoxazolidines: the effects of steric factor and hydrophobic chain length on the corrosion inhibition of mild steel in acidic medium

Several new isoxazolidines having varying degree of steric environment and hydrophobic chain length, prepared efficiently using single-step nitrone cycloaddition reactions, are tested for corrosion inhibition of mild steel in 1 M and 5 M HCl at 50-70 °C range by gravimetric and electrochemical methods. All compounds have shown very good corrosion inhibition efficiency (IE%) in acidic solution. Steric crowding around the nitrogen centres and hydrophobic chain lengths as well as increase in temperature (in the presence of the inhibitor in the higher concentration range 100-400 ppm) are found to increase the inhibition efficiency of the isoxazolidines. Thermodynamic parameters (ΔG°_ads, ΔH°_ads, ΔS°_ads) for the adsorption process and kinetic parameters for the metal dissolution (or hydrogen evolution) reaction in the presence of one of the isoxazolidines were determined. Experimental results agree with the Temkin adsorption isotherm. The inhibition of corrosion in 1 M HCl, influenced by both physi- and chemi-sorption, was found to be under mixed control, but predominantly under cathodic control.     

含菌介质中MDOPD对SRB菌及生物膜腐蚀的抑制作用

用动电位扫描极化曲线、原子力显微镜和电子探针等方法研究了SRB生物膜在培养基介质中对于含咪唑杂环的双季铵盐化合物MDOPD的敏感性．结果表明：含菌介质中，MDOPD吸附在电极表面，形成完整致密的有机保护膜，对电极的腐蚀反应具有良好的抑制作用，SRB的代谢及腐蚀产物也难以在电极表面直接吸附和沉积，从而降低了SRB生长代谢的次生过程（包括酸浸蚀等）对腐蚀的促进作用；同时也降低了介质中的SRB参与碳钢腐蚀的机会．     

三辊张力单元张力曲线的绘制

运用弹塑性弯曲理论建立了相应三辊张力单元的数学力学模型,得出了张力计算式,绘制了张力曲线,讨论了压下量设置与张力、带钢厚度及带钢材质的关系,所绘张力曲线与日本进口设备实际应用张力曲线相符。研究结果表明,张力增量与带钢厚度近似成抛物线关系,与带钢屈服强度成正比;压下量<60 mm时,压下量的变化对各种厚度带钢的张力增量影响较大,当带材厚度≥7 mm时,不能轻易加大压下量;对于薄带钢,应适当增加压下量以保证张力单元可靠地产生所需的卷取张力。研究结果可用来指导张力单元装置的设计及操作模式的制定。