The use of Global Navigation Satellite Systems (GNSS) for positioning has revolutionized the way location data is be- ing collected. The NAVigation System with Time And Ranging Global Positioning System (GPS), which i...The use of Global Navigation Satellite Systems (GNSS) for positioning has revolutionized the way location data is be- ing collected. The NAVigation System with Time And Ranging Global Positioning System (GPS), which is a principal component of the global navigation satellite system (GNSS);is a satellite-based radio navigation system that provides positions of points of interest and time information to users. GPS positional accuracy can be improved by using differential corrections obtained through a technique called Differential GPS (DGPS), which is known to provide the most accurate positioning results. Differential correction can be applied in real time at the data collection phase or in the of- fice, at the post-processing phase. DGPS is generally used for positioning purposes through static or kinematics GPS surveys. In static GPS surveys, one receiver is placed at a point whose coordinates are known and the other receiver is placed over a point whose coordinates are desired. In kinematic surveys, one receiver remains at one point (base station) normally with known coordinates, and the other receiver (rover) moves from point to point in the project area. Kinematic surveys in which points positions are computed on-the-fly (OTF) are known as real-time kinematic (RTK). RTK surveys provide real-time locations of points of interest needed in many applications. Positioning with wide-area GNSS networks is basically based on the DGPS and RTK concepts. Observables from a network of a finite number of GPS receivers over an area are processed by a server at a central location (network server) and made available to the users of the network later or in real-time through radio-based, satellite, or wireless communications. This article provides a review of the concept and application of positioning with wide-area GNSS networks.展开更多
随着网络技术的持续演进,为满足日益增长的通信需求,急需对油气自控网络进行升级。基于虚拟交换实例(Virtual Switching Instance,VSI)/虚拟扩展局域网(Virtual eXtensible Local Area Network,VXLAN)隧道通信技术,开展网际互连协议第4...随着网络技术的持续演进,为满足日益增长的通信需求,急需对油气自控网络进行升级。基于虚拟交换实例(Virtual Switching Instance,VSI)/虚拟扩展局域网(Virtual eXtensible Local Area Network,VXLAN)隧道通信技术,开展网际互连协议第4版/网际互连协议第6版(Internet Protocol Version 4/Internet Protocol Version 6,IPv6)双栈部署与效能评估相关研究。通过确立双栈架构的设计原则与目标,构建分层网络架构,实现VSI/VXLAN隧道与IPv4/IPv6双栈架构的深度融合,完成核心网络设备与接入层网络的双栈部署,并实施安全域划分。基于多维度效能评估指标体系,采集多测点、多负载条件下的性能数据,量化评估网络的安全防护能力。实验结果表明,该方案可显著提升油气自控网络在协议兼容性、传输效率与安全性方面的综合性能,为其数字化升级提供理论支撑与实践路径。展开更多
根据IEC61850标准,归纳分析了数字化变电站内的各种典型数据流,运用明确的数学模型对其进行了详细描述,最终得出各类报文的数据包生成图。以IEC 61850-5规定的D2-1典型变电站为例,对其中存在的各种数据流及其流量大小进行了详细说明;利...根据IEC61850标准,归纳分析了数字化变电站内的各种典型数据流,运用明确的数学模型对其进行了详细描述,最终得出各类报文的数据包生成图。以IEC 61850-5规定的D2-1典型变电站为例,对其中存在的各种数据流及其流量大小进行了详细说明;利用OPNET仿真软件,应用优先级标签技术,对基于虚拟局域网(virtual local area network,VLAN)的集成型变电站综合通信网络进行了仿真分析,进一步研究了变电站通信网络中VLAN的配置方法和原则,对有无VLAN的星型网络进行了对比研究。结果表明,VLAN技术可以较好地解决变电站中的网络资源竞争以及部分安全性问题。展开更多
文摘The use of Global Navigation Satellite Systems (GNSS) for positioning has revolutionized the way location data is be- ing collected. The NAVigation System with Time And Ranging Global Positioning System (GPS), which is a principal component of the global navigation satellite system (GNSS);is a satellite-based radio navigation system that provides positions of points of interest and time information to users. GPS positional accuracy can be improved by using differential corrections obtained through a technique called Differential GPS (DGPS), which is known to provide the most accurate positioning results. Differential correction can be applied in real time at the data collection phase or in the of- fice, at the post-processing phase. DGPS is generally used for positioning purposes through static or kinematics GPS surveys. In static GPS surveys, one receiver is placed at a point whose coordinates are known and the other receiver is placed over a point whose coordinates are desired. In kinematic surveys, one receiver remains at one point (base station) normally with known coordinates, and the other receiver (rover) moves from point to point in the project area. Kinematic surveys in which points positions are computed on-the-fly (OTF) are known as real-time kinematic (RTK). RTK surveys provide real-time locations of points of interest needed in many applications. Positioning with wide-area GNSS networks is basically based on the DGPS and RTK concepts. Observables from a network of a finite number of GPS receivers over an area are processed by a server at a central location (network server) and made available to the users of the network later or in real-time through radio-based, satellite, or wireless communications. This article provides a review of the concept and application of positioning with wide-area GNSS networks.
文摘随着网络技术的持续演进,为满足日益增长的通信需求,急需对油气自控网络进行升级。基于虚拟交换实例(Virtual Switching Instance,VSI)/虚拟扩展局域网(Virtual eXtensible Local Area Network,VXLAN)隧道通信技术,开展网际互连协议第4版/网际互连协议第6版(Internet Protocol Version 4/Internet Protocol Version 6,IPv6)双栈部署与效能评估相关研究。通过确立双栈架构的设计原则与目标,构建分层网络架构,实现VSI/VXLAN隧道与IPv4/IPv6双栈架构的深度融合,完成核心网络设备与接入层网络的双栈部署,并实施安全域划分。基于多维度效能评估指标体系,采集多测点、多负载条件下的性能数据,量化评估网络的安全防护能力。实验结果表明,该方案可显著提升油气自控网络在协议兼容性、传输效率与安全性方面的综合性能,为其数字化升级提供理论支撑与实践路径。
文摘根据IEC61850标准,归纳分析了数字化变电站内的各种典型数据流,运用明确的数学模型对其进行了详细描述,最终得出各类报文的数据包生成图。以IEC 61850-5规定的D2-1典型变电站为例,对其中存在的各种数据流及其流量大小进行了详细说明;利用OPNET仿真软件,应用优先级标签技术,对基于虚拟局域网(virtual local area network,VLAN)的集成型变电站综合通信网络进行了仿真分析,进一步研究了变电站通信网络中VLAN的配置方法和原则,对有无VLAN的星型网络进行了对比研究。结果表明,VLAN技术可以较好地解决变电站中的网络资源竞争以及部分安全性问题。
