The anti-aircraft system plays an irreplaceable role in modern combat. An anti-aircraft system consists of various types of functional entities interacting to destroy the hostile aircraft moving in high speed. The con...The anti-aircraft system plays an irreplaceable role in modern combat. An anti-aircraft system consists of various types of functional entities interacting to destroy the hostile aircraft moving in high speed. The connecting structure of combat entities in it is of great importance for supporting the normal process of the system. In this paper, we explore the optimizing strategy of the structure of the anti-aircraft network by establishing extra communication channels between the combat entities.Firstly, the thought of combat network model(CNM) is borrowed to model the anti-aircraft system as a heterogeneous network. Secondly, the optimization objectives are determined as the survivability and the accuracy of the system. To specify these objectives, the information chain and accuracy chain are constructed based on CNM. The causal strength(CAST) logic and influence network(IN) are introduced to illustrate the establishment of the accuracy chain. Thirdly, the optimization constraints are discussed and set in three aspects: time, connection feasibility and budget. The time constraint network(TCN) is introduced to construct the timing chain and help to detect the timing consistency. Then, the process of the multi-objective optimization of the structure of the anti-aircraft system is designed.Finally, a simulation is conducted to prove the effectiveness and feasibility of the proposed method. Non-dominated sorting based genetic algorithm-Ⅱ(NSGA2) is used to solve the multiobjective optimization problem and two other algorithms including non-dominated sorting based genetic algorithm-Ⅲ(NSGA3)and strength Pareto evolutionary algorithm-Ⅱ(SPEA2) are employed as comparisons. The deciders and system builders can make the anti-aircraft system improved in the survivability and accuracy in the combat reality.展开更多
Quality of Service (QoS) in Wireless Sensor Networks (WSNs) is a challenging area of research because of the limited availability of resources in WSNs. The resources in WSNs are processing power, memory, bandwidth, en...Quality of Service (QoS) in Wireless Sensor Networks (WSNs) is a challenging area of research because of the limited availability of resources in WSNs. The resources in WSNs are processing power, memory, bandwidth, energy, communication capacity, etc. Delay is an important QoS parameter for delivery of delay sensitive data in a time constraint sensor network environment. In this paper, an extended version of a delay aware routing protocol for WSNs is presented along with its performance comparison with different deployment scenarios of sensor nodes, taking IEEE802.15.4 as the underlying MAC protocol. The performance evaluation of the protocol is done by simulation using ns-2 simulator.展开更多
为降低现有列车网络控制系统(train control and management system,TCMS)端到端时延、抖动不确定性对列车控制功能时间确定性的影响,提高列车控制功能迭代效率,基于下一代列车网络控制系统(next generation TCMS,NG-TCMS),提出通信与...为降低现有列车网络控制系统(train control and management system,TCMS)端到端时延、抖动不确定性对列车控制功能时间确定性的影响,提高列车控制功能迭代效率,基于下一代列车网络控制系统(next generation TCMS,NG-TCMS),提出通信与计算资源联合调度模型,将端到端确定性从网络层延伸至列车控制功能。首先,结合NG-TCMS中时间敏感网络提供的全局统一时间基准,将列车控制功能拆分为具有依赖关系的状态采集、逻辑计算、数据转发、命令执行任务,并通过有向无环图进行形式化。以最小化执行时间为调度目标,分别通过一阶逻辑约束转化为可满足性模理论(satisfiability modulo theories,SMT)问题进行最优求解,以及抽象为整数线性规划(integer linear programming,ILP)问题进行最优求解。同时,提出基于任务松弛度和抖动继承值的快速求解方法,将一次性求解所有任务的大规模调度转化为迭代求解单任务或双任务的小规模调度,以解决控制功能数量陡增导致调度问题复杂度激增,SMT方法和ILP方法难以快速求解的问题。最后,参考CR450动车组列车控制功能设计算例,以30 min为求解时间上限,分析SMT方法、ILP方法、快速求解方法在求解时间与所得调度方案资源利用率方面的性能差异。结果表明,快速求解方法能在20 min内完成1000个含零抖动和抖动约束的控制功能调度,高效调度系统资源,满足NG-TCMS快速迭代需求。研究结果可为基于NG-TCMS构建具有端到端时间确定性的列车网络控制功能及任务调度方法提供参考。展开更多
即时配送外延不断拓展,配送规模和范围增加,使得骑手在配送过程中安全事故频发。城市交通网络复杂且订单容量与平台预测存在偏差,高峰时段订单激增迫使骑手采取挂置车把等非标准装载方式,显著增加了交通事故风险。因此,提出了考虑城市...即时配送外延不断拓展,配送规模和范围增加,使得骑手在配送过程中安全事故频发。城市交通网络复杂且订单容量与平台预测存在偏差,高峰时段订单激增迫使骑手采取挂置车把等非标准装载方式,显著增加了交通事故风险。因此,提出了考虑城市交通网络特性下带容量约束的即时配送路径优化问题。证明了该问题的下界,针对特殊网络、一般网络设计了double judgment condition(DJC)、judge path and load weighted(JPL)和wait and serve(W&S)策略,并采用最坏情形分析法证明策略的竞争比。通过算例验证算法的有效性,分析JPL和W&S策略分别在不同订单密度、最大非对称系数、订单容量比重等情形下的表现。研究结果表明:JPL策略的适用性较高,在订单密度较高、大容量订单较多、非对称系数较小的城市交通网络性能最好;W&S策略更适用于订单密度较低、大容量订单较多、非对称系数较大城市交通网络。研究结论提供了不同情形下考虑容量约束的配送策略,通过实时优化路径减少非标准装载需求,保障了骑手安全配送。展开更多
基金supported by the National Natural Science Foundation of China(72071206).
文摘The anti-aircraft system plays an irreplaceable role in modern combat. An anti-aircraft system consists of various types of functional entities interacting to destroy the hostile aircraft moving in high speed. The connecting structure of combat entities in it is of great importance for supporting the normal process of the system. In this paper, we explore the optimizing strategy of the structure of the anti-aircraft network by establishing extra communication channels between the combat entities.Firstly, the thought of combat network model(CNM) is borrowed to model the anti-aircraft system as a heterogeneous network. Secondly, the optimization objectives are determined as the survivability and the accuracy of the system. To specify these objectives, the information chain and accuracy chain are constructed based on CNM. The causal strength(CAST) logic and influence network(IN) are introduced to illustrate the establishment of the accuracy chain. Thirdly, the optimization constraints are discussed and set in three aspects: time, connection feasibility and budget. The time constraint network(TCN) is introduced to construct the timing chain and help to detect the timing consistency. Then, the process of the multi-objective optimization of the structure of the anti-aircraft system is designed.Finally, a simulation is conducted to prove the effectiveness and feasibility of the proposed method. Non-dominated sorting based genetic algorithm-Ⅱ(NSGA2) is used to solve the multiobjective optimization problem and two other algorithms including non-dominated sorting based genetic algorithm-Ⅲ(NSGA3)and strength Pareto evolutionary algorithm-Ⅱ(SPEA2) are employed as comparisons. The deciders and system builders can make the anti-aircraft system improved in the survivability and accuracy in the combat reality.
文摘Quality of Service (QoS) in Wireless Sensor Networks (WSNs) is a challenging area of research because of the limited availability of resources in WSNs. The resources in WSNs are processing power, memory, bandwidth, energy, communication capacity, etc. Delay is an important QoS parameter for delivery of delay sensitive data in a time constraint sensor network environment. In this paper, an extended version of a delay aware routing protocol for WSNs is presented along with its performance comparison with different deployment scenarios of sensor nodes, taking IEEE802.15.4 as the underlying MAC protocol. The performance evaluation of the protocol is done by simulation using ns-2 simulator.
文摘为降低现有列车网络控制系统(train control and management system,TCMS)端到端时延、抖动不确定性对列车控制功能时间确定性的影响,提高列车控制功能迭代效率,基于下一代列车网络控制系统(next generation TCMS,NG-TCMS),提出通信与计算资源联合调度模型,将端到端确定性从网络层延伸至列车控制功能。首先,结合NG-TCMS中时间敏感网络提供的全局统一时间基准,将列车控制功能拆分为具有依赖关系的状态采集、逻辑计算、数据转发、命令执行任务,并通过有向无环图进行形式化。以最小化执行时间为调度目标,分别通过一阶逻辑约束转化为可满足性模理论(satisfiability modulo theories,SMT)问题进行最优求解,以及抽象为整数线性规划(integer linear programming,ILP)问题进行最优求解。同时,提出基于任务松弛度和抖动继承值的快速求解方法,将一次性求解所有任务的大规模调度转化为迭代求解单任务或双任务的小规模调度,以解决控制功能数量陡增导致调度问题复杂度激增,SMT方法和ILP方法难以快速求解的问题。最后,参考CR450动车组列车控制功能设计算例,以30 min为求解时间上限,分析SMT方法、ILP方法、快速求解方法在求解时间与所得调度方案资源利用率方面的性能差异。结果表明,快速求解方法能在20 min内完成1000个含零抖动和抖动约束的控制功能调度,高效调度系统资源,满足NG-TCMS快速迭代需求。研究结果可为基于NG-TCMS构建具有端到端时间确定性的列车网络控制功能及任务调度方法提供参考。
文摘为了满足航空器经济性的制造需求,降低航空器内部的有效载荷,使用无线代替有线已经成为机载网络转型升级的重要方向,然而传统无线技术难以满足机载网络中时间敏感业务的实时性传输需求.因此,通过明确机载无线通信网络(airborne wireless communication network, AWCN)的应用特点,设计了AWCN结合机载骨干交换网络的混合拓扑架构;综合考虑了节点无冲突、信道无干扰、路径依赖与端到端时延需求,构建了时间触发的AWCN确定性调度应该满足的一阶逻辑形式;理论分析了不同信道数量下完成调度所需要的最少时隙数量与制约端到端时延的主要因素,并证明了稳态时数据流在网关处的信息年龄期望值;设计了基于整数规划的调度方法,并针对大规模网络中决策变量多、约束之间耦合性高而导致的求解效率低的缺陷,提出了一种增量式求解策略.最后,通过实验验证了确定性调度模型与理论分析的有效性,并讨论了不同调度影响因子对数据流总时延与调度规模的影响.
文摘即时配送外延不断拓展,配送规模和范围增加,使得骑手在配送过程中安全事故频发。城市交通网络复杂且订单容量与平台预测存在偏差,高峰时段订单激增迫使骑手采取挂置车把等非标准装载方式,显著增加了交通事故风险。因此,提出了考虑城市交通网络特性下带容量约束的即时配送路径优化问题。证明了该问题的下界,针对特殊网络、一般网络设计了double judgment condition(DJC)、judge path and load weighted(JPL)和wait and serve(W&S)策略,并采用最坏情形分析法证明策略的竞争比。通过算例验证算法的有效性,分析JPL和W&S策略分别在不同订单密度、最大非对称系数、订单容量比重等情形下的表现。研究结果表明:JPL策略的适用性较高,在订单密度较高、大容量订单较多、非对称系数较小的城市交通网络性能最好;W&S策略更适用于订单密度较低、大容量订单较多、非对称系数较大城市交通网络。研究结论提供了不同情形下考虑容量约束的配送策略,通过实时优化路径减少非标准装载需求,保障了骑手安全配送。
