直流电机电刷磨损预测的粒子滤波方法

针对直流电机电刷磨损的跟踪与预测问题,提出了一种改进型粒子滤波器的电机电刷磨损状态演变预测方法。首先建立直流电机的动态模型,通过电刷磨损仿真分析获得一定时间间隔的电流输出数据,此输出数据作为测量数据用作为预测模型的输入。接着,根据测量数据的变化规律建立电机电刷磨损预测的模型形式,然后通过采用所提出的多项式重采样粒子滤波方法来预测电机电刷磨损状态的演变。案例数据分析结果表明,所提出的基于粒子滤波的电刷磨损预测方法是有效的且计算过程简便。     

Effect of ultrasonic vibration on the dechromisation corrosion of a CuCr alloy in HCl solution

The effect of ultrasonic vibration on the dechromisation corrosion of a CuCr alloy in HC1 solution was studied and the corrosion mechanisms were analyzed. It is found that ultlasonic vibration reduces the dechromisation incubation time, accelerates the dechromisafion corrosion rate, decreases the temperature and concentration of HC1 solution, and when the dechromisation occurs it seriously weakens the microstmcture of dechromisation layer. It is concluded that ultrasonic vibration can accelerate destruction of the passivation film on the Cr surface and increase the activities of Cl^- and Cr.     

细磨粒超声珩磨ZrO2表面特征研究

采用细粒度金刚石油石，对氧化锆工程陶瓷进行了超声珩磨与普通珩磨的试验研究。试验结果表明，磨削条件对被加工表面的粗糙度和表面破碎影响较大：1)超声珩磨的表面和普通珩磨表面相比，磨削沟槽不仅宽且底部平坦，网纹较均匀，珩磨沟槽的顶部较平整，并且不存在断续现象。2)普通珩磨的延性域加工临界磨削深度不超过1．5m，而超声珩磨方式下，其延性域临界磨削深度可达到3μm。3)普通珩磨方式下，在磨削速度100～150r/m，磨削深度1．0～1．5μm时，可取得较低粗糙度值；超声珩磨方式下，在磨削速度150～190r/m，磨削深度1．0～1．5μm时，取得较低的粗糙度值，同等条件下比普通珩磨低1～2级。     

Ultrasonic technique for measuring porosity of plasma-sprayed alumina coatings

Porosity is an important factor in plasma-sprayed coatings, especially ceramic coatings. Excessive poros-ity can adversely affect the performance of the coated component in various ways. An ultrasonic nonde-structive measurement technique has been developed to measure porosity in plasma-sprayed alumina coatings. The technique is generic and can be extended to other ceramic coating systems. To test the tech-nique, freestanding alumina coatings with varying levels of porosity were fabricated via plasma spray. Samples with varying porosity, obtained through innovative fabrication techniques, were used to gener-ate a calibration curve. The ultrasonic velocity in the low-frequency range was found to be dependent on the density of freestanding coatings (measured via Archimedian techniques). This dependence is the basis of the development of a technique to measure the density of coatings.     

激光超声激励技术研究

激光超声是一种新型无损检测技术，它利用调Q激光器控制能量，采用合适的电路处理技术可在复合材料和金属上产生有价值的超声波信号。介绍了激光超声的产生原理和试验装置，并在表面未处理的不同厚度的复合材料和几何形状复杂的零件部位进行了激光超声激励试验。结果表明该方法可在以上构件中产生有效超声波信号，弥补了常规超声激励方式的不足。     

Evaluation of TiAI and 40Cr diffusion bonding quality using ultrasonic reflection spectrum

Combined with ultrasonic pulse-echo technique, reflection spectrum analysis was introduced to evaluate TiAl and 40Cr diffusion bonding quality. Frequency dependence of reflection coefficient was used to distinguish perfect bonding from imperfect bonding. It is found that the reflection coefficient from perfect bonding interface does not vary with frequency. When the size of imperfections is much smaller than the wavelength of ultrasound, the reflection coeffwient depends on frequency. When the size of imperfections is the same order of or even larger than the wavelength of ultrasound, the reflection coeffwient does not exhibit frequency dependence. However the amplitude of imperfect interface is higher than the amplitude of perfect bonding interface. A combination of reflection spectrum analysis and ultrasonic pulse-echo technique provides more accurate information about the bonding quality of dissimilar materials.     

复杂结构电子束焊缝超声无损评价

采用超声C扫描成像方法检测了复杂结构电子束焊缝.根据这类焊接结构的特点,采用模拟试件,代替真实试件,简化了试验条件.着重分析了大深宽比工件内超声的传播特性,在此基础上,经反复试验研制了聚焦效果较好的声透镜,将声透镜应用于平探头上进行检测试验,为了验证检测结果的可靠性,对试件上典型位置进行了破坏性试验分析.结果表明:自制探头的检测灵敏度较高,超声检测结果与界面缺陷分布情况具有较好的一致性,说明超声C扫描成像检测方法是电子束焊缝质量评价的有效手段.     

NdFeB磁体的二次化学镀耐蚀性能

研究了NdFeB磁体表面超声波化学镀和二次化学镀Ni- P合金的耐腐蚀性，用扫描电子显微镜和X射线衍射仪分析了镀层的组织结构，结果表明，该工艺制备的镀层明显地提高了NdFeB磁体的耐蚀性能.     

气体雾化贮氢电极合金Ml（Ni,Co,Mn,Ti）5的活化性能

研究了感应熔炼后随炉冷却和经不同处理的气体雾化贮氢电极合金Ｍｌ（Ｎｉ，Ｃｏ，Ｍｎ，Ｔｉ）５的电化学活化特性。结果表明，氢化前后合金内能的变化是影响活化性能的原因，因表面覆盖氧化膜或任何其它原因所引起的附加内能越大，或氢化时氢原子进入四面体或八面体间隙位置所引起应变能越大，活化越困难。     

超声和微波作用下制备纳米氧化铜

以氢氧化铜为前驱体，在超声和微波作用下制备纳米氧化铜。借助透射电镜（TEM）、X射线衍射（XRD）、粒度分析等手段，研究了超声、分散剂、微波等制备条件的影响。结果表明：采用该法可以制备粒径小（15nm）、分散良好的纳米氧化铜粉体；超声可使前驱体Cu（OH）2转变为CuO，并粉碎颗粒间形成的团聚；分散剂通过表面修饰抑制颗粒的团聚；微波加热促进了前驱体的转化，并抑制颗粒的长大。