论船位误差圆及其应用

本文指出[1]、[2]对船位均方误差圆缺乏科学的严格的定义,提供的均方误差圆覆盖真船位的概率某些数据是不正确的;同时从概率统计的角度论述船位均方误差圆的定义,计算覆盖真船位的概率、95%误差圆半径及船位误差圆在航海中的一些应用。     

大鼠持续吸入麻醉手术固定板的研制及其应用

介绍了一种实验动物持续吸入麻醉手术固定板的研制及在教学和科研中的应用，该麻醉手术固定板在原手术固定板的基础上对一些部件进行了改进，改进后的手术固定板不仅方便了实验操作，节省了实验材料，而且还能有效地改善室内环境，有助于保护实验者的身体健康。     

数控机床之数控系统的诊断与维护

通过对数控机床的构成与特点的概述,进而对数控系统的常见故障进行了分析,并对数控系统的故障诊断与维护方法,以及应注意的事项作了较为详细的阐述。     

基于功能重构的电路故障修复技术研究

针对电路故障测试过程中存在故障难以定位和修复的问题,提出了一种基于功能重构的故障修复方法。该方法使用全集测试集对被测电路进行精确测试,以测试向量中的响应值与实际电路中的响应结果进行对比,实现对故障的精确定位。当被测电路的所有故障信息被收集后,采用功能重构的原理对出现故障的电路进行修复,在实现功能修复同时,降低了故障修复难度。文章给出了这种故障检测与功能重构的总体实现框图,并分别对模拟电路和数字电路的故障详细阐述了功能重构的方法。     

Surface breakdown of printed circuit board under magnetic field with reduced pressure

Epoxy resin laminate onto which a pair of copper foil was printed was employed as test samples.The samples were placed in an artificial atmospheric chamber, which was vacuumed by a rotary pump from 100 kPa to 5 kPa.The magnetic field was produced by permanent magnets that were assembled to make E×B drift away from, into and parallel to the sample surface, respectively.Magnetic flux density was adjusted at 120 mT, 180 mT and 240 mT respectively.By applying a negative bias voltage between the electrodes, the time to surface breakdown was recorded.Obtained results show that when E×B is into the surface, the time to the breakdown is shortened;when E×B is away from the surface, the time to the breakdown is delayed;when E×B is parallel to the surface, the time to the breakdown remains approximately the same as the case without magnetic field.With the decrease of pressure, the time to the breakdown increases and the effect of magnetic field on breakdown appears to be strengthened.