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针对高速动车组车底底架横梁的应变场反演问题,基于模态叠加法和传感器优化配置理论,提出一种根据部分测点的实测单向应变反演结构空间应变场的方法。以结构的应变模态为输入,以模态坐标独立性为目标,基于信息熵理论建立了传感器优化配置的数学模型,再根据模态坐标和振型采用正则化方法反演结构应变场。仿真计算结果表明,无噪声干扰下,反演的精度较高,最大均方误差为9.87×10-12,并且正则化方法可以有效抑制噪声对结果的影响。搭建了基于光纤光栅传感系统的测试试验台,基于实测应变数据和模态结果反演应变场,结果表明,反演后的应变幅值相对误差带为1.21%~10.79%,反演数据和实测数据的均方误差带为0.80~3.69。该方法能够准确识别结构的模态坐标,为获取高速列车关键结构的应变场分布提供参考。 相似文献
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The molybdenum powders with average particle size of 3 μm were coated with copper by electroless plating. The influence of pretreatment,solution composition and plating conditions on electroless copper plating was studied. The copper-coated molybdenum powders were examined by SEM and XRD. Results indicate that a series of optimization methods is used to add activated sites before electroless copper plating. Taking TEA and EDTA as chief and assistant complex agents respectively,2,2’-bipyridyl and PEG as double stabilizers,the Mo powders are coated with copper successfully with little Cu2O contained,at the same time,Mo-Cu composite powders with copper content of 15-85 wt% can be obtained. The optimal values of pH,temperature and HCHO concentration are 12-13,60-65 ℃ and 22-26 mL/L,respectively. 相似文献
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采用化学镀方法对平均粒径3 μm的Mo粉末进行化学镀铜,探讨了工艺条件对化学镀铜的影响.利用扫描电镜(SEM)对钼粉镀覆前后形貌进行观察;X射线衍射(XRD)对所得复合粉末相组成进行了分析.结果表明:采用化学镀的方法可以成功地获得铜含量(质量分数)为15%~85%的Mo/Cu复合粉末,复合粉末中无Cu2O,表面平滑,但有团聚现象;化学镀铜过程中,pH值的临界值为12,随着pH值增加,镀速加快,但是pH值过高会引起甲醛分解,镀液中pH值的最佳范围在12~13之间;随着温度和甲醛含量的升高,镀速加快,镀液稳定性降低,镀液中甲醛含量和温度最佳范围分别为22~26 mL/L,60~70℃. 相似文献
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轴承作为风力发电机的重要传动机构,工作环境恶劣,存在较高故障率,一旦发生故障将造成巨大经济损失。因此,准确地预测轴承的剩余寿命对于实现轴承的健康在线监测和视情维修具有重要的工程应用价值。采用基于数据驱动的剩余寿命间接预测方法,首先,使用短时傅里叶变换对降噪后的轴承高频振动信号进行时频分析,将时频域特征进行结合并充分考虑振动信号的局部特征和时变性;然后通过多层卷积自编码器网络对获得的时频图进行自动压缩和特征提取,获得轴承退化过程中的一维健康指标曲线;最后构建多层门控循环单元网络模型,将轴承的一维健康指标曲线作为模型的输入,映射到轴承的剩余寿命。使用FEMTO轴承数据集作为实验数据,验证了所提方法的有效性。 相似文献
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采用二次通用旋转组合设计法,建立了钼粉粒度、氧含量与还原工艺参数间关系的经验数学模型,绘制了双工艺参数与钳粉粒度、氧含量间关系的函数图,得出了制备钼粉的最佳工艺,即还原温度为950~1000℃,料层厚度为1.8~2.0cm,推舟速度为90~100min/boat。 相似文献
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Mo powders with average particle size of 3 μm were attempted to coat with copper by electroless plating technique. The effect of the solution composition and plating conditions on the electroless copper plating was studied. The uncoated and coated powders were subjected to the microstructural studies by SEM and the phases were analyzed by XRD. The results indicate that the Mo powders are coated with copper, at (he same time, Mo-Cu composite powders with Cu content ranging from 15% to 85% (mass fraction) can be obtained. The optimal values of pH, HCHO concentration and temperature are in the ranges of 12-13, 22-26 ml/L and 60-65℃, respectively. The diffusion-shrinkage autocatalytic model is suggested for the growth mechanism of electroless coating over the surface. 相似文献
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采用化学镀技术对平均粒度为3μm的Mo粉末进行化学镀铜,探讨了镀液组成及工艺条件对Mo粉末化学镀铜的影响,利用X射线衍射、SEM对所得粉末进行了分析。结果表明:以TEA为主络合剂,EDTA为辅助络合剂,并加入2,2′-联吡啶和聚乙二醇作为稳定剂,可以成功地在Mo粉上镀铜,复合粉末铜含量为15%~85%(wt)。化学镀铜过程中pH的最佳值在12-13之间,甲醛浓度的最佳值在22-26mL/L之间。 相似文献
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