后勤装设备可修备件送修方法研究

针对后勤装设备可修备件价格昂贵而保障经费非常有限的问题,提出了后勤装备备件送厂修理的原则与要求,重点阐述了后勤装备备件送厂修理的各种途径,对做好后勤装备备件送厂修理工作具有重要参考价值。     

应用P矩阵法分析S型声表面波器件特性

在128°Y切割X传播方向上的LiNbO3基片上设计并研制了S型声表面波器件。它将输入叉指换能器激发的声表面波中心对称分成两路并由各自输出叉指换能器检测输出。采用P矩阵法分析推导了输入叉指换能器加电信号,一输出叉指换能器检测输出时的一次时延信号、三次渡越反射信号和五次渡越反射信号与所加电信号的关系式。采用网络分析仪测量了S型声表面波器件的幅度特性,同时,由门函数处理后获得其三次和五次渡越反射信号的幅度特性以验证理论推导的正确性。     

浅析校园网络管理

文章介绍了网络管理的3项主要工作内容:设备管理、服务管理和用户管理,同时简单介绍了相关的软件工具和技术原理。     

浅议矿用捕捉器的技术改进

本文针对矿用碰爪式捕捉器在矿井斜巷的提升运输中存在事故,跑车总是撞断矿车轴的现象,为解决此类事故的重现,考虑为碰爪式捕捉器增设弹性吸能缓冲装置,简单介绍了其工作原理,同时对增设的吸能缓冲装置提出合理的设计方案,并对吸能缓冲装置所选用的弹簧进行了计算检验。     

铁路空调发电车24V启动电池放亏的原因及防范

文章介绍了发电车柴油机24 V启动电池放亏后所造成的危害,分析了24 V启动电池放亏的主要原因,提出对启动电源线检修卡控,提高充电装置检修质量,加装48V转24V应急转换装置,改造旧型蓄电池,加强24V电池维护保养等措施,确保柴油发电机组正常运转及发电车的安全运行。     

寻呼机用SAW滤波器D281的性能分析

本文解剖了寻呼机用国外样管Ｄ２８１，并模拟了其衍射频响。实测结果表明，与数值模拟相符。     

Antitakeover devices and management efficiency: An empirical study using accounting measures

Separation of corporate ownership and control creates an environment whereby the agent (management) may pursue self-interests at the expense of the principal (stockholders). One mechanism protecting stockholders from self-interested management is the market for corporate control, or the takeover market. Antitakeover devices impede the operations of this market. This paper reports on the study of one type of antitakeover device, the supermajority nonfair price amendment. This device is particularly onerous, and if antitakeover devices do protect inefficient management as has been alluded to in the literature, then evidence of inefficiency should be observable for companies adopting supermajority nonfair price amendments.To test the above proposition, we examine the difference in performance over a seven-year period (1) Between firms having supermajority nonfair price amendments and a set of matched firms that do not have these devices, and (2) between firms with these amendments and their respective industries. In both tests, performance was lower for the firms adopting these amendments, which suggests that these devices are used to protect inefficient management. Further, the argument that managers of firms which adopt antitakeover devices so that they can take a long-term outlook at the expense of short-term profitability was not supported by the data.     

美国JOY公司7LS3采煤机中的电气回路保护

本文探讨美国久益 7LS采煤机先进的电气回路保护。通过电流传感器、电阻温度装置 (RTD)和牵引电机断路器 ,有效地保护电路 ,防止了过载、短路和电机过热等对生产造成的影响     

高频稳度无线电遥控电路的设计

无线电遥控电路应用广泛，本文介绍了一种采用声表面波（SAW）谐振器作为频率源器件的高Q值、高频稳度的无线遥控发射和接收电路，解决了传统的LC振荡电路频稳度差及频率漂移较大的问题。