铁路光传送网络是高速铁路地面基础设施的神经中枢,为避免网络故障给铁路运营带来巨大损失,重点研究光传送网P-Cycle(Pre-configured Cycle)保护技术,提出在圈扩展时以所有候选圈上未保护工作容量的方差、冗余度两个指标为比较标准的RVP...铁路光传送网络是高速铁路地面基础设施的神经中枢,为避免网络故障给铁路运营带来巨大损失,重点研究光传送网P-Cycle(Pre-configured Cycle)保护技术,提出在圈扩展时以所有候选圈上未保护工作容量的方差、冗余度两个指标为比较标准的RVPA(Redundancy and Variance Based P-Cycle Construction Algorithm)算法。圈扩展的过程中,算法将选择方差与冗余度能同时满足条件的候选圈作为本轮扩展圈,有效限制了完成保护的P-Cycle圈个数;圈扩展停止条件中,当UPL与参数M、冗余度的大小关系满足条件时,则停止圈扩展,从而限制圈上节点数,使圈个数与圈长度得到有效均衡;在仿真过程中,利用泛欧网络拓扑COST239对RVPA算法进行仿真,并对比分析不同M值下的性能。仿真结果表明,在相同空闲资源与待保护工作容量设定下,参数M取0.5时效果最优,并且RVPA算法的保护容量效率、所需圈的个数、算法整体耗时、总冗余度均优于已有的POCA(P-Cycle Optimization Configuration Heuristic Algorithm)算法。展开更多
基于共享风险链路组(SRLG,shared risk link group)和P圈(P-Cycles,pre-configured cycles)的概念,研究了SRLG约束下p-Cycles的构造问题,引入SRLG完全分离p-Cycles的概念,基于SRLG的简单p-Cycles构造算法和获得更多p-Cycles的SRLG约束...基于共享风险链路组(SRLG,shared risk link group)和P圈(P-Cycles,pre-configured cycles)的概念,研究了SRLG约束下p-Cycles的构造问题,引入SRLG完全分离p-Cycles的概念,基于SRLG的简单p-Cycles构造算法和获得更多p-Cycles的SRLG约束下的圈扩展算法提出的SRLG约束下的p-Cycles配置算法(SCAA),实现在光网络中优化配置SRLG完全分离的p-Cycles。通过计算机仿真表明,SCAA最小容量配置方案可以预留更少的网络资源,而SCAA优化容量配置方案可以实现p-Cycles快速配置容量,SCAA算法可以保障配置SRLG分离p-Cycles的高保护效能,使网络具备单SRLG故障恢复能力。展开更多
Pre-configured cycles （p-cycles） can attain high capacity efficiency and fast protection switching times in wavelength division multiplexing （WDM） networks. This article proposes the weighted straddling link algor...Pre-configured cycles （p-cycles） can attain high capacity efficiency and fast protection switching times in wavelength division multiplexing （WDM） networks. This article proposes the weighted straddling link algorithm（WSLA） for generating a subset of all cycles that can guarantee 100% restorability in case of dual link failure, and give an integer linear programming（1LP） formulation that solves the shared p-cycles design problem minimizing the total spare capacities. Numerical result shows that our method can achieve 100% dual link failure restorability with acceptable spare capacity. The larger standard deviation of demand set and the larger node degree network, the better the shared p-cycles scheme performs.展开更多
Aiming at minimizing spare capacity for optical WDM networks, we propose a new heuristic algorithm for preconfigured protection cycle (p-cycle) design. Numerical results show that the spare capacity obtained by our ne...Aiming at minimizing spare capacity for optical WDM networks, we propose a new heuristic algorithm for preconfigured protection cycle (p-cycle) design. Numerical results show that the spare capacity obtained by our new algorithm is very close to the optimal solution.展开更多
A novel prefigured-cycle(P-Cycle)algorithm was proposed to improve the protection success ratio for asymmetric traffic in mesh optical networks.The proposed algorithm was simulated in a Pan-European COST239 network en...A novel prefigured-cycle(P-Cycle)algorithm was proposed to improve the protection success ratio for asymmetric traffic in mesh optical networks.The proposed algorithm was simulated in a Pan-European COST239 network environment under an asymmetric dynamic traffic model.The experimental results show that the proposed algorithm has lower capacity redundancy and higher utilization rate of configured resources than traditional P-Cycle methods.Network performance can be improved when implementing this algorithm under single-link failure circumstances.The system behavior is analyzed under different traffic volumes and the configuration strategy is also investigated for the heavyload and light-load networks respectively.展开更多
In future high-capacity wavelength division multiplexed(WDM)optical networks,the failure of a network component such as a fiber link can lead to severe disruption in the networks’traffic.Hence,it is imperatively impo...In future high-capacity wavelength division multiplexed(WDM)optical networks,the failure of a network component such as a fiber link can lead to severe disruption in the networks’traffic.Hence,it is imperatively important to provide fast and full protection in WDM optical networks.In this paper,we propose a new approach,called shared preconfigured protection cycles(shared-p-cycles),for the design of survivable WDM networks.We develop an integer linear program(ILP)formulation to solve the problem of shared-p-cycles design for WDM networks with and without wavelength conversion.Numerical results show that the shared-p-cycles design is more efficient in the use of spare capacity and requires much less spare capacity than the conventional pcycles design.展开更多
分组传送网(Packet Transport Network,PTN)能够兼容多种网络,诸如ATM、SDH、以太网、PDH、PPP/HDLC等,被广泛地应用到各种组网通信,PTN能够有机地结合数据技术和传输技术,使运营商的基础网络优势得到很大程度的提高。目前,分组传送网(P...分组传送网(Packet Transport Network,PTN)能够兼容多种网络,诸如ATM、SDH、以太网、PDH、PPP/HDLC等,被广泛地应用到各种组网通信,PTN能够有机地结合数据技术和传输技术,使运营商的基础网络优势得到很大程度的提高。目前,分组传送网(PTN)在多网络通讯、传输带宽、流量、信息安全等方面无法满足用户需求,文中设计出新型的PTN网络安全架构,根据业务及流量选择架构类型,并引入融入OTN核心组网和p-Cycle保护算法,通过使用OTN核心组网方案,使汇聚机房带宽和数据传输能力大大提高,具有较强的扩容能力,通过使用p-Cycle保护算法并构建组网拓扑图,提高了PTN网络信息数据传递的安全性能。文中还设计出PTN组网软件架构,便于用户应用、查询。实验表明,设计的方案大大降低了组网难度,提高了网络速度、服务质量,具有较好的网络可扩展性和安全性。展开更多
In agricultural soils, phosphorus is often limited, leading farmers to employ artificial supplementation through both inorganic and organic fertilization methods due to its restricted availability. Soil fertilization ...In agricultural soils, phosphorus is often limited, leading farmers to employ artificial supplementation through both inorganic and organic fertilization methods due to its restricted availability. Soil fertilization has the potential to augment both the abundance and diversity of bacterial communities. Our study aimed to assess the effects of phosphate amendments, derived from natural phosphate rock, and chemical fertilizers (TSP, NPK), on the density and diversity of bacterial communities within the study plots. We developed and applied eight phosphate amendments during the initial cultivation cycle. Soil samples were collected post 1st and 2nd cultivation cycles, and the quantification of both total and cultivable phosphate-solubilizing bacteria (PSB) was conducted. Additionally, we analyzed bacterial community structure, α-diversity (Shannon Diversity Index, Evenness Index, Chao1 Index). The combination of natural phosphate rock (PR) and chemical fertilizers (TSP, NPK) significantly increased (p 7 bacteria/g dry soil) and phosphate-solubilizing bacteria (0.01 to 6.8 × 107 PSB/g dry soil) in comparison to unamended control soils. The diversity of bacterial phyla (Firmicutes, Actinobacteria, Proteobacteria, Halobacterota, Chloroflexia) observed under each treatment remained consistent regardless of the nature of the phosphate amendment applied. However, changes in the abundance of the bacterial phyla populations were observed as a function of the nature of the phosphate amendment or chemical fertilizer. It appears that the addition of excessive natural phosphate rock does not alter the number and the diversity of soil microorganisms population despite successive cultivation cycles. However, the addition of excessive chemical fertilizer reduces soil microorganisms density and structure after the 2nd cultivation cycle.展开更多
文摘铁路光传送网络是高速铁路地面基础设施的神经中枢,为避免网络故障给铁路运营带来巨大损失,重点研究光传送网P-Cycle(Pre-configured Cycle)保护技术,提出在圈扩展时以所有候选圈上未保护工作容量的方差、冗余度两个指标为比较标准的RVPA(Redundancy and Variance Based P-Cycle Construction Algorithm)算法。圈扩展的过程中,算法将选择方差与冗余度能同时满足条件的候选圈作为本轮扩展圈,有效限制了完成保护的P-Cycle圈个数;圈扩展停止条件中,当UPL与参数M、冗余度的大小关系满足条件时,则停止圈扩展,从而限制圈上节点数,使圈个数与圈长度得到有效均衡;在仿真过程中,利用泛欧网络拓扑COST239对RVPA算法进行仿真,并对比分析不同M值下的性能。仿真结果表明,在相同空闲资源与待保护工作容量设定下,参数M取0.5时效果最优,并且RVPA算法的保护容量效率、所需圈的个数、算法整体耗时、总冗余度均优于已有的POCA(P-Cycle Optimization Configuration Heuristic Algorithm)算法。
文摘基于共享风险链路组(SRLG,shared risk link group)和P圈(P-Cycles,pre-configured cycles)的概念,研究了SRLG约束下p-Cycles的构造问题,引入SRLG完全分离p-Cycles的概念,基于SRLG的简单p-Cycles构造算法和获得更多p-Cycles的SRLG约束下的圈扩展算法提出的SRLG约束下的p-Cycles配置算法(SCAA),实现在光网络中优化配置SRLG完全分离的p-Cycles。通过计算机仿真表明,SCAA最小容量配置方案可以预留更少的网络资源,而SCAA优化容量配置方案可以实现p-Cycles快速配置容量,SCAA算法可以保障配置SRLG分离p-Cycles的高保护效能,使网络具备单SRLG故障恢复能力。
基金This work is supported by the National Science Fund for Distinguished Young Scholars （60325104）；the National Natural Science Foundation of China （60572021）；the SRFDP of M0E （20040013001）.
文摘Pre-configured cycles （p-cycles） can attain high capacity efficiency and fast protection switching times in wavelength division multiplexing （WDM） networks. This article proposes the weighted straddling link algorithm（WSLA） for generating a subset of all cycles that can guarantee 100% restorability in case of dual link failure, and give an integer linear programming（1LP） formulation that solves the shared p-cycles design problem minimizing the total spare capacities. Numerical result shows that our method can achieve 100% dual link failure restorability with acceptable spare capacity. The larger standard deviation of demand set and the larger node degree network, the better the shared p-cycles scheme performs.
文摘Aiming at minimizing spare capacity for optical WDM networks, we propose a new heuristic algorithm for preconfigured protection cycle (p-cycle) design. Numerical results show that the spare capacity obtained by our new algorithm is very close to the optimal solution.
基金supported by the Hi-Tech Research and Development Program of China (No.2006AA01Z246)the National Natural Science Foundation of China (Grant No.60602004).
文摘A novel prefigured-cycle(P-Cycle)algorithm was proposed to improve the protection success ratio for asymmetric traffic in mesh optical networks.The proposed algorithm was simulated in a Pan-European COST239 network environment under an asymmetric dynamic traffic model.The experimental results show that the proposed algorithm has lower capacity redundancy and higher utilization rate of configured resources than traditional P-Cycle methods.Network performance can be improved when implementing this algorithm under single-link failure circumstances.The system behavior is analyzed under different traffic volumes and the configuration strategy is also investigated for the heavyload and light-load networks respectively.
基金supported by China Postdoctoral Science Foundation (Nos.20070420013,200801030)Open Fund of National Laboratory on Local Fiber-Optic Communication Networks&Advanced Optical Communication Systems,Peking University,China,Guangxi Science Foundation (No.0731003)Science Foundation of Guangxi University (No.X071032).
文摘In future high-capacity wavelength division multiplexed(WDM)optical networks,the failure of a network component such as a fiber link can lead to severe disruption in the networks’traffic.Hence,it is imperatively important to provide fast and full protection in WDM optical networks.In this paper,we propose a new approach,called shared preconfigured protection cycles(shared-p-cycles),for the design of survivable WDM networks.We develop an integer linear program(ILP)formulation to solve the problem of shared-p-cycles design for WDM networks with and without wavelength conversion.Numerical results show that the shared-p-cycles design is more efficient in the use of spare capacity and requires much less spare capacity than the conventional pcycles design.
文摘分组传送网(Packet Transport Network,PTN)能够兼容多种网络,诸如ATM、SDH、以太网、PDH、PPP/HDLC等,被广泛地应用到各种组网通信,PTN能够有机地结合数据技术和传输技术,使运营商的基础网络优势得到很大程度的提高。目前,分组传送网(PTN)在多网络通讯、传输带宽、流量、信息安全等方面无法满足用户需求,文中设计出新型的PTN网络安全架构,根据业务及流量选择架构类型,并引入融入OTN核心组网和p-Cycle保护算法,通过使用OTN核心组网方案,使汇聚机房带宽和数据传输能力大大提高,具有较强的扩容能力,通过使用p-Cycle保护算法并构建组网拓扑图,提高了PTN网络信息数据传递的安全性能。文中还设计出PTN组网软件架构,便于用户应用、查询。实验表明,设计的方案大大降低了组网难度,提高了网络速度、服务质量,具有较好的网络可扩展性和安全性。
文摘In agricultural soils, phosphorus is often limited, leading farmers to employ artificial supplementation through both inorganic and organic fertilization methods due to its restricted availability. Soil fertilization has the potential to augment both the abundance and diversity of bacterial communities. Our study aimed to assess the effects of phosphate amendments, derived from natural phosphate rock, and chemical fertilizers (TSP, NPK), on the density and diversity of bacterial communities within the study plots. We developed and applied eight phosphate amendments during the initial cultivation cycle. Soil samples were collected post 1st and 2nd cultivation cycles, and the quantification of both total and cultivable phosphate-solubilizing bacteria (PSB) was conducted. Additionally, we analyzed bacterial community structure, α-diversity (Shannon Diversity Index, Evenness Index, Chao1 Index). The combination of natural phosphate rock (PR) and chemical fertilizers (TSP, NPK) significantly increased (p 7 bacteria/g dry soil) and phosphate-solubilizing bacteria (0.01 to 6.8 × 107 PSB/g dry soil) in comparison to unamended control soils. The diversity of bacterial phyla (Firmicutes, Actinobacteria, Proteobacteria, Halobacterota, Chloroflexia) observed under each treatment remained consistent regardless of the nature of the phosphate amendment applied. However, changes in the abundance of the bacterial phyla populations were observed as a function of the nature of the phosphate amendment or chemical fertilizer. It appears that the addition of excessive natural phosphate rock does not alter the number and the diversity of soil microorganisms population despite successive cultivation cycles. However, the addition of excessive chemical fertilizer reduces soil microorganisms density and structure after the 2nd cultivation cycle.
