换向器正挤压数值模拟

针对换向器的结构特点,应用DEFORM软件对两种毛坯正挤压成形方案金属流动情况进行数值模拟,得到不同毛坯在正挤压成形过程中的变形规律.模拟结果能够用来指导工艺实践,从而缩短产品开发周期,提高产品质量.     

简单直流电动机的三种模型

针对教师自制简单直流电动机模型难的问题,在简化和创新的基础上,提出了"简化电动机——无需换向器"模型和"创新电动机——无需线圈"模型。制作难度降低,同时体现了创新思维,使活动趣味性强,体现了寓教于乐理念。     

金粉云母板工艺参数研究试验

本文介绍了采用金粉云母板作为换向器片间云母的工艺研究试验。     

Alternative and Secure Direct Communication with W State

A theoretical scheme for alternative and secure direct communication is proposed. The communication is based on controlled quantum teleportafiou via W state. After insuring the security of the quantum channels （a set of qubits in the W states）, Alice encodes the secret messages directly on a sequence of particle states and transmits them to Bob supported by Charlie, or to Charlie supported by Bob, using controlled quantum teleportafiou. Bob or Charfie can read out the encoded messages directly by the measurement on his qubits. In this scheme, the controlled quantum teleportafiou transmits Alice＇s message without revealing any information to a potential eavesdropper. Because there is no a transmission of the qubits carrying the secret messages between legitimate parties in the public channel, it is completely secure for direct secret communication if perfect quantum channel is used. We also discuss that when one of the three legitimate parties does not cooperate with others because of some reasons, the remaining two persons can still communicate with each other by entanglement purification. The main feature of this scheme is that the communicate between two sides is alternative but depends on the agreement of the third, and more over, the communication between two sides does not suspend with loss of one of three qubits （ i.e., one of the three legitimate parties does not cooperate with others）.     

遥控电动模型飞机基础知识（4）：动力电机（上） 直流永磁电机的特性及其使用

迄今为止，航模所用的动力电机大部分为直流永磁电机。读者拿起手头的电机，只要通过其通风孔便可以看到在它的铁壳里有一对瓦形磁钢和一个转子。在转子上除了硅钢片铁芯和绕在它上面的线圈之外，还有一个圆柱形换向器。换向器由互相靠得很近而又互相绝缘的铜制换向片构成。换向片的数目同绕组的数目相等，通常为3个，称为三极式。高级的电机也有5极和7极的，不能取双数。     

换向器式电动机电磁骚扰抑制方法研究

带换向器式电动机在工作时会产生严重的电磁骚扰,根据其产生电磁骚扰的原因及途径,阐述了抑制带换向器式电动机电磁骚扰的方法,并提出了一些改进措施。     

谈谈换向器设计的几个问题

本文从以下几个方面讨论直流电动机换向器的设计:结构的选择,换向器紧固螺栓的设计,选用合适的换向片悬臂锥面的倾斜角,选用恰当的换向器压圈和套筒接触面的公差配合,采用较先进的计算技术.     

谈谈换向器设计的几个问题

本文从以下几个方面讨论直流电动机换向器的设计:结构的选择,换向器紧固螺栓的设计,选用合适的换向片悬臂锥面的倾斜角,选用恰当的换向器压圈和套筒接触面的公差配合,采用较先进的计算技术。     

流量标准装置中闭式换向器对流量测量的影响

介绍了测量过程中闭式换向器对流体流速的干扰现象,比较、分析了闭式与开式换向器对测量的影响。     

直流电机防止火花产生的措施

直流电机在工作运行时,电刷与换向器之间很容易产生火花,而火花对电机的运行会带来危害,当火花的级别太大时,甚至会烧坏电机的运行设备。因此,我们要防止过大的火花的产生。本文通过对火花产生的原因进行分析,以此来找出在实际中的解决方法。