含沙量对分离鳃的水沙分离影响试验

为研究含沙量对分离鳃水沙分离效果的影响,通过对分离鳃与普通管进行9组不同含沙量的静水沉降试验,运用粘性颗粒的沉降特性分析了含沙量与沉速的关系。结果表明,含沙量对泥沙沉速影响很大,含沙量越大,泥沙下沉相同距离时所需的沉降时间越长,泥沙的沉速越小;在同一含沙量下分离鳃的沉速始终大于普通管沉速,当含沙量为10~80 kg/m3时,分离鳃沉速更大,水沙分离效果最佳。     

一次氧化剂O2体积分数对富氧燃烧煤粉着火距离影响的数值模拟

对40 kW同轴射流富氧煤粉燃烧试验系统进行数值模拟,研究了在总体O2体积分数和氧化剂过量系数一定的条件下,不同一次氧化剂O2体积分数对同轴射流富氧燃烧煤粉着火距离的影响,分析了低一次氧化剂O2体积分数下富氧燃烧煤粉着火及火焰稳定性.结果表明:在总体O2体积分数为40％和氧化剂过量系数为1.15的条件下,当一次氧化剂O2体积分数为20.9％时,着火距离较小,为附着火焰;当一次氧化剂O2体积分数减小至14.6％、10.0％和5.5％时,着火距离明显增大,着火延迟,为分离火焰;适当提高二次氧化剂预热温度有利于低一次氧化剂O2体积分数下富氧燃烧的煤粉着火及火焰稳定.     

基于马氏距离算法的配电网故障定位系统研究

为了满足智能配电网故障定位的实时性、可靠性、准确性等需求,提出了基于马氏距离算法的配电网故障定位系统。以IDT智能配电终端作为系统运行状态电气量实时采集核心模块,按F检验获得元件电气量变化显著性概率P值初判故障元件和故障类型后,通过马氏距离算法准确定位故障区域和故障元件,并采用IEEE9节点系统的三相短路故障对配电网故障定位系统进行测试分析。仿真结果表明,该系统能真实地反映配电网故障后故障区域和故障元件的电气量变化,可满足智能配电网在线故障定位需求。     

一种单片机控制的重锤式料位计设计

结合固体料位测量的实际需求,给出一种单片机控制的重锤式料位计的设计方案。分析了测量机理,介绍了料位计的机械结构、控制部分设计。该系统具有造价成本低、通用性强、精度高、可实现远程控制等特点,完全满足物位检测要求,可代替国外同类产品。     

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 主要介绍了使用单片机实现多路容栅位移传感器的数据信号的采集、处理与传输。CD4514BE以及STC89系列单片机实现对多路容栅位移传感器的信号采集与处理,中继仪通过无线通讯与上位机相连,实现数据在上位机的显示与实时存储。通过实践证明该系统符合要求,使用方便,精确度高,同时实现数据的实时储存与显示。     

纯水射流间接强化对18CrNiMo7-6钢表面粗糙度和残余应力的影响

目的减小高压水射流强化中冲蚀现象对材料表面的影响。方法选择水射流喷射压力、喷射靶距和覆盖小钢珠直径为可变参数,对18CrNiMo7-6渗碳合金钢进行高压水射流强化单因素试验。运用三维表面形貌测量系统和X射线残余应力分析仪对试验后的材料进行测量分析。结果随着压力的增大,表面粗糙度增加,残余应力最大可达693 MPa,但继续增大喷射压力反而会使残余压应力减小。随着靶距的增加,表面残余应力几乎直线减小,表面粗糙度则在靶距为110 mm时达到最小值0.77μm。随着小钢珠直径的增加,表面残余压应力先增大后减小,最大值为782 MPa;表面粗糙度先变小后增大,最小值为0.76μm。结论水射流喷射压力、喷射靶距和覆盖小钢珠直径对18CrNiMo7-6钢的表面粗糙度和残余应力影响明显。同时,每个参数在不同的变化范围,对材料表面主要的影响方式不同,对材料的表面粗糙度和表面残余压应力的影响也存在着差异。     

光纤干涉绝对测距技术

提出一种利用短扫描导轨实现１ｍ以上绝对距离测量的光纤干涉测距新方法：测系统由定位干涉仪和扫描干涉仪组成,定位干涉仪采用准光光源实现测量中的定位瞄准,扫描干涉仪完成距离的测量。     

Correlation between laser-wire distance and Nd：YAG laser ＋ P-GMA hybrid welding heat input parameters

In laser+P-GMA hybrid welding,laser-wire distance is an important parameter to describe the distance from laser spot to the center of the pulsed gas metal arc.The experiments results show that the optimal laser-wire distance with the deepest weld penetration increases with welding current and laser power being increased and decreases with welding speed being increased.Welding current,laser power and welding speed determine the hybrid welding heat input in laser+arc hybrid welding process,so there is a correlation between the optimal laser-wire distance and the hybrid heat input welding parameters for the deepest weld penetration: the optimal laser-wire distance increases with the heat input being increased.The positive correlation between the optimal laser-wire distance and the hybrid welding heat input is induced by the characteristics of the limited influence of P-GMA welding process on laser transmission and the dependence of weld penetration of hybrid welding on laser power.     

Effects of critical plasma spray parameter and spray distance on wear resistance of Al2O3-8 wt.%TiO2 coatings plasma-sprayed with nanopowders

Effects of plasma spraying conditions on wear resistance of nanostructured Al₂O₃-8 wt.%TiO₂ coatings plasma-sprayed with nanopowders were investigated in this study. Five kinds of nanostructured coatings were plasma-sprayed on a low-carbon steel substrate by varying critical plasma spray parameter (CPSP) and spray distance. The coatings consisted of fully melted region of γ-Al₂O₃ and partially melted region, and the fraction of the partially melted regions and pores decreased with increasing CPSP or decreasing spray distance. The hardness and wear test results revealed that the hardness of the coatings increased with increasing CPSP or decreasing spray distance, and that the hardness increase generally led to the increase in wear resistance, although the hardness and wear resistance were not correlated in the coating fabricated with the low CPSP. The main wear mechanism was a delamination one in the coatings, but an abrasive wear mode also appeared in the coating fabricated with the low CPSP. According to these wear mechanisms, the improvement of wear resistance in the coating fabricated with the low CPSP could be explained because the improved resistance to fracture due to the presence of partially melted regions might compensate a deleterious effect of the hardness decrease.     

基于坐标变换的曲线曲面求交算法

利用坐标变换的方法,给出了二次曲线和二次曲面求交的解析算法。利用拉格朗日乘子法求解二次曲线和二次曲面之间的最小距离,给出了曲线与曲面相切的条件。算法表明,坐标变换可以简化求交运算表达式,使求交算法易于实现。根据得出的相切条件,可以有效地判断曲线、曲面是否有交,对相切情况的计算结果进行修正,可提高奇异情况下的求交稳定性。算法已在清软英泰公司开发的自主版权3维CAD软件GEMS中得到应用。