利用AIS数据库实现船舶状态数据监测与挖掘

在现有海上船舶监控系统中,无论是基于雷达信号数据还是视频监控数据,由于信号传输机制及最终信号处理都需要一定时间,其实效性并不高,应用范围也有一定的局限性。AIS(自动识别系统)是一种工作在高频段的自主广播系统,能够实现岸基与船舶、船舶与船舶之间实施交换航行状态、位置坐标以及气象变换等信息。本文在研究现有AIS原理及结构的基础上,基于AIS数据交互提出一种实现船舶状态数据监控的控制平台,并给出仿真结果。     

A note on a provable secure encryption scheme

A Cramer-Shoup scheme was modified in a variant way.The major advantage with respect to Kurosawa-Desmedt scheme is that it saves a key parameter and produces shorter ciphertext.The proof of security shows that our scheme can be instantiated with any computational secure key derivation and message authentication functions.Thus it extends the applicability of the Kurosawa-Desmedt scheme and improves its effciency.     

轨道交通变电所综合自动化系统接口协议分析

介绍了轨道交通变电所自动化系统中典型的网络设备结构图,以及常用的物理接口:串行数据接口、以太网数据接口、硬线接口等.根据实际情况,对目前轨道交通变电所自动化系统常用的接口协议如串行RS485接口、以太网、现场总线的优、缺点进行了分析总结.     

船舶电站实时监控系统通信软件设计

实现船舶电站监控的关键是通信技术,文章基于Modbus通信协议,提出一种在LabVIEW虚拟仪器环境下实现PC机与单片机实时通信的方法,设计了船舶电站实时监控系统通信软件,完成对船舶电站多套柴油发电机组的现场监控.给出了监控系统的具体实施方案,详细讨论了通信协议的设定及通信程序的编程要点.该通信软件的开发不仅为本科教学提供了实验平台,而且能够很方便地移植到其它实际应用系统,具有较好的工程实用价值.     

A Reliable Adaptive High-Definition Transmission System for Distance Learning

There is an increasing demand for supporting high-quality real-time audiovisual services for the next generation wired and wireless networks. However, due to variety of bandwidths of different networks, it is a great challenge for deployment. In this paper, a novel high-definition (HD) video transmission system was proposed which depends upon reliable compound multicast protocols and QoS control over the various kinds of networks. This system detects client's network condition and assigns it to a proper proxy. Each proxy is capable of detecting network parameters and adaptively tuning such transport parameters as bit rate, video resolution, frame rate and QoS mechanisms to this condition. It also provides FEC error recovery under consideration of characteristics of MPEG4 video codec. Our simulation demonstrates that different network clients such as ADSL, CERNET, and CERNET2 can receive more video reliability with less delay.     

Efficient Protocol-Proving Algorithm Based on Improved Authentication Tests

A new efficient protocol-proving algorithm was proposed for verifying security protocols. This algorithm is based on the improved authentication tests model, which enhances the original model by formalizing the message reply attack. With exact causal dependency relations between messages in this model, the protocol-proving algorithm can avoid the state explosion caused by asynchronous. In order to get the straight proof of security protocols, three authentication theorems are exploited for evaluating the agreement and distinction properties. When the algorithm terminates, it outputs either the proof results or the potential flaws of the security protocol. The experiment shows that the protocol-proving algorithm can detect the type flaw attack on Neuman-Stubblebine protocol, and prove the correctness of NSL protocol by exploring only 10 states.     

LabVIEW在电站监控系统中的应用

主要研究了LabVIEW在电站监控系统中的应用;通过基于MODBUS协议的串口网络将船舶电站各发电机组及柴油机的信息存储到监控系统数据库,利用QUEUE技术解决了串口通讯的实时性问题;同时根据数据处理结果对相应发电机组执行操作,实时显示各机组的状态信息,进一步提高了船舶电站自动化的水平。