高速列车通信网络技术特点及其应用

现代列车朝高速化、自动化、舒适化方向发展已经成为必然趋势.列车通信网络已成为高速列车控制系统的关键技术.它能够通过对列车运行及车载设备动作的相关信息进行集中管理,从而保障列车安全高速运行.介绍了列车通信网络的两条总线,即纹线式列车总线(WTB)和多功能车辆总线(MVB),并分析了两层网络拓扑结构.根据现场总线技术在我国高速列车上的应用情况,比较了WTB、MVB、LonWorks、CAN等几种总线的特点,根据其特点可选取不同的应用领域.     

A bintree energy approach for colour image segmentation using adaptive channel selection

A new hierarchical approach called bintree energy segmentation was presented for color image segmentation. The image features are extracted by adaptive clustering on multi-channel data at each level and used as the criteria to dynamically select the best chromatic channel, where the segmentation is carried out. In this approach, an extended direct energy computation method based on the Chan-Vese model was proposed to segment the selected channel, and the segmentation outputs are then fused with other channels into new images, from which a new channel with better features is selected for the second round segmentation. This procedure is repeated until the preset condition is met. Finally, a binary segmentation tree is formed, in which each leaf represents a class of objects with a distinctive color. To facilitate the data organization, image background is employed in segmentation and channels fusion. The bintree energy segmentation exploits color information involved in all channels data and tries to optimize the global segmentation result by choosing the ＂best＂ channel for segmentation at each level. The experiments show that the method is effective in speed, accuracy and flexibility.     

A new channel allocation scheme for hierarchical wireless networks

A channel allocation scheme for hierarchical wireless networks was proposed in terms of the connection-level quality of service. The channel allocation scheme was analyzed using both horizontal channel borrowing and vertical traffic overflowing. Pre-emptive priority strategies are used to classify real-time services and non-real-time services, real-time service is given higher priority for it is allowed to pre-empt channels used by non-real-time service. Some channel borrowing thresholds and acceptance ratios are used to avoid channel locking or dynamic power control, which can also be dynamically adjusted according to network load. Simula-tion results show that the proposed schemes can improve the system performance.     

"船舶通信业务"课程教学方法的探索

“船舶通信业务”是航海专业学生必修的一门专业课,由于该课程涉及的条例、法规和公约的内容比较多,内容相对枯燥,导致本课程教与学都有一定困难;经过几年的教学研究和实践,我们总结出一套比较合适的教学方法,希望对于该课程的教学有所帮助。     

运行中市政管廊隧道的维修加固

我国早期浅埋暗挖市政管廊隧道标准较低,目前病害多发。为了治理断面狭小、内部净空限界要求不高的市政管廊隧道的病害,结合大连某电缆隧道维修加固工程,采用病害检测及分析、方案综合比选和施工实践的方法,介绍暗挖市政管廊隧道的维修加固过程。得出主要结论如下： 隧道病害检测应从结构变形、衬砌强度、衬砌背后、裂缝及渗漏水等方面详细调查,分析病害成因,评定劣化等级; 通过检测分析结构,选择合理的结构加固措施,劣化严重的市政管廊隧道应优先选择增设内衬的维修改造方案; 施工阶段应重点处理好无水施工、对既有结构和内部管线的保护和在狭小空间施工的问题。     

浅析软件无线电技术在现代通信系统中的应用

简要的介绍了软件无线电的发展背景以及软件无线电的定义,并概述软件无线电在通信系统中所发挥的作用极其主要功能.随着科学技术的迅猛发展,无线电技术与软件技术的结合称为当今新型通信的发展方向,并在各领域得到了广泛的应用.但是就我国的现状来讲,无线电发展还处于初级阶段,各项技术还不是很成熟.所以加速发展无线电技术并使其在各领域都拥有广泛的应用称为目前无线电发展的主要趋势.根据自身掌握的信息以及多年的工作经验对无线电与软件相结合的技术进行以下介绍.     

基于IP网络的数字录音联络通信系统的设计与应用

分析当前铁路联络防护存在的不足,设计和建设一套基于网络的数字录音联络通信系统,实现信号全线覆盖、各车站通信联网、多级调度指挥、通话录音自动存储等功能,提高了安全生产管理水平。     

基于通信的移动闭塞列车控制系统

随着计算机和通信技术的发展，城市轨道交通信号系统也在不断地发展。自上世纪90年代以来，基于通信的移动闭塞列车控制系统CBTC（Corn-munication-Based Train Contro1）受到了日益广泛的重视。CBTC系统是利用列车和地面间的双向数据通信设备，使地面信号设备可以得到每一列车连续的位置信息，并据此计算出每一列车的运行权限，动态更新发送到列车，列车根据接收到的运行权限和自身的运行状态，[第一段]     

地铁杂散电流防护体系研究

通过对地铁直流供电系统杂散电流的形成、危害及传统排流法防护体系的分析,针对排流法防护体系中存在的问题,提出了新型的泄漏电缆 等电位连接法防护改进体系。     

电离层特点与链路预算仿真

短波通信的效果随着电离层的变化而发生变化。详细分析电离层的结构以及对短波通信的影响，进行了对天波链路损耗的预测，行采用Matlab实现了几种典型情况的损耗预测仿真，实地通信结果表明本文的分析与仿真能够满足通常情况下短波通信的要求？