关于科协若干问题的思索

本文从几个主要问题入手，论述了科协历史、性质、任务、地位和作用与面临的新形势、新要求。     

对机车集中供电状态进行监测的探讨

针对25T新型旅客列车机车集中供电过程中出现的断电问题,提出对集中供电状态进行监测的总体构想,并对所用设备的性能以及需要达到的技术指标要求进行了分析.     

机车信号监测系统联网应用研究

针对机车信号检测日常监测工作存在的问题，以及现有机车信号监测记录设备的实际应用情况的目的，从提高系统运用效果和完善使用出发，区别不同层次的应用情况，提出与此相适应的机车信号监测系统联网方案。     

津浦线防洪抬道综合施工技术难点及关键

在繁忙的津浦线上实施大规模的抬道施工在铁路史上尚属首次，无成功的经验可以参考，无论工程数量，还是施工难度、运输组织复杂性等方面都堪称前所未有，本文对路基、桥梁、线路施工关键点进行了概述。     

河船目测船位的原理及应用

船舶航行在海洋上是用天文航海、地文航海、雷达、电测向仪和GPS等方法测定船位,将测定的船位绘在海图上再制定航向,船按该航向航行.内河航道狭窄、弯曲,要求驾驶员时刻掌握本船在航道上的位置,以正确的航向航行,安全地操纵船舶.     

风机并联布置在地铁中的应用

结合地铁运营的特点，对地铁地下车站公共区通风空调系统和区间隧道通风系统风机并联布置的优点和合理性进行分析，同时对并联风机的选型配置提出解决方案和建议。     

补偿电容的测试与分析

秦沈线自秦皇岛站至沈阳北站，全长404．6kin。其中新修里程约394km，车站采用法国的SEI计算机联锁系统，它将车站联锁与列车运行控制合二为一，实现了列控联锁一体化。区间采用UM2000无绝缘轨道电路，上行载频2000，2600Hz，下行载频1700，2300Hz；每个电气绝缘节设1个空心线圈SVAC、2个调谐单元BU和2个补偿调谐单元DB。     

货物区舱室通风的设计要求

本文介绍了IBC规则对货物区域舱室的通风要求及其在29000DWT化学品船的应用。     

138 m双薄壁空心高墩翻模施工技术

结合葫芦河特大桥 138m双薄壁空心高墩施工 ,详述了百米以上的空心高墩采用翻模施工方法 ,以及翻模的设计参数和稳定性计算。     

DESIGN OF A DIGITAL SIGNATURE SCHEME BASED ON FACTORING AND DISCRETE LOGARITHMS

Objective Focusing on the security problem of authentication and confidentiality in the context of computer networks, a digital signature scheme was proposed based on the public key cryptosystem. Methods Firstly,the course of digital signature based on the public key cryptosystem was given. Then, RSA and ELGamal schemes were described respectively. They were the basis of the proposed scheme. Generalized ELGamal type signature schemes were listed. After comparing with each other, one scheme, whose Signature equation was (m r)x=j s modФ(p) , was adopted in the designing. Results Based on two well-known cryptographic assumptions, the factorization and the discrete logarithms, a digital signature scheme was presented. It must be required that s“ was not equal to p‘q“ in the signing procedure, because attackers could forge the signatures with high probabilities if the discrete logarithms modulo a large prime were solvable. The variable public key “e“ is used instead of the invariable parameter “3“ in Ham‘s signature scheme to enhance the security. One generalized ELGamal type scheme made the proposed scheme escape one multiplicative inverse operation in the signing procedure and one modular exponentiation in the verification procedure.Conclusion The presented scheme obtains the security that Harn‘s scheme was originally claimed. It is secure if the factorization and the discrete logarithms are simultaneously unsolvable.