基于链路可靠性的两跳QoS路由

针对工业无线传感器网络对路由协议的QoS要求，研究了一种基于链路可靠性的两跳QoS路由（Link-Reliability Based Two-Hop Routing for QoS Guarantee in Industrial Wireless Sensor Networks， LRTHQR）.采用两跳速度策略和数据优先级调度策略提高实时性，采用改进的信任评估模型以选择可信路径进行路由，采用基于接收功率的链接概率和数据包重传次数作为衡量链路可靠性的指标，同时采用能够综合考虑节点剩余能量和转发能耗的转发策略，以改善网络寿命.仿真结果显示：与未考虑链路可靠性的NCSRT （NodeCredible Security Routing for IWSN Based on THTR）算法相比， LRTHQR算法在丢包率、时延以及包平均能耗方面有着明显优势；与同样侧重QoS要求的LRTHR （Link-Reliability based Two-Hop Routing）算法相比， LRTHQR算法在截止期错失率、路由开销以及包平均能耗方面有着显著提升.     

What’s the middle ground? Institutionalized vs. emerging water-related stakeholder engagement processes

Abstract

In this day and age, it is widely argued that stakeholder engagement in water-related decision-making processes yields many benefits, including legitimacy, acceptance and trust. Key legal frameworks, such as the European Water Framework Directive and the Aarhus Convention, have spurred the emergence of formal forms of stakeholder engagement. On the other hand, many engagement processes are spontaneous and self-organized. This article investigates the strategies used in formal (government-led) and informal (bottom-up) engagement processes in search of a middle ground. To this end, case studies in the Netherlands, the United States, Uganda and Ethiopia are analyzed using the OECD’s stakeholder engagement checklist. We conclude with reflection on the ways forward to make formal and informal stakeholder engagement complementary.     

网络匿名扫描系统设计及优化

针对网络扫描工具在进行扫描时面临的溯源问题，提出了一种匿名网络扫描系统。首先将匿名系统与网络扫描工具结合以实现匿名扫描；然后在现有匿名系统的基础上实现了该系统的本地私有化；接着通过流量分析发现，Nmap的多进程扫描因为代理链的原因会变成单进程扫描而导致其扫描扫描性能较低；最后提出了一种基于多Namp进程并发的性能优化方案，将总体扫描任务分割为多个扫描任务，并分配给多个单独的Nmap进程并行运行。实验结果表明，该性能优化方案的扫描时延接近正常扫描情况下的时延，达到了提高匿名扫描系统性能的目的。因此，该优化后的网络匿名扫描系统在阻碍溯源的同时提升了扫描效率。     

车联网环境下基于节点认知交互的路由算法

针对车联网（IoV）环境下消息传输效率低下、网络资源开销较大等诸多问题，提出一种适用于城市交通场景下基于车辆节点认知交互的路由算法。首先，依据信任理论提出节点认知交互度的概念，并在此基础上对车联网中的车辆节点进行分类，赋予它们不同的认知交互度初值；同时还引入车辆节点交互时间、交互频率、车辆节点物理间隔距离、间隔跳数以及消息生存时间等影响因子，进而构建了车辆节点认知交互评估模型。基于该模型计算并更新节点的认知交互度，并通过比较对应车辆节点间的认知交互度值来选取认知交互度相对较高的邻居节点作为中继节点进行消息转发。仿真实验结果表明，与Epidemic和Prophet路由算法相比，所提路由算法有效提高了消息投递率并降低了消息投递时延，同时显著降低了网络资源的开销，有助于提升车联网环境的消息传输质量。     

WSNs中规避攻击者的源位置隐私保护路由协议

为了保证无线传感器网络（Wireless Sensor Networks，WSNs）中的源节点位置隐私安全，同时实现安全性能和网络能耗的均衡，提出了WSNs中规避攻击者的源节点位置隐私路由协议，该协议假设节点具有检测攻击者的能力，通过发出危险警告消息使路由路径上的节点采取路由改变策略，使攻击者无法回溯到源节点，延长了源节点保持位置隐私的安全时间。理论分析和仿真实验表明，该协议在消耗较少的通信开销的情况下保证了源节点位置的高度隐私。     

求解带时间窗车辆路径问题的改进型烟花算法

针对带时间窗车辆路径问题,为寻求组合优化问题最优解,构建总运输成本最小数学模型。由于烟花算法搜索半径不能自适应调整,算法后期易陷入局部最优,故对爆炸算子进行改进,使最优烟花搜索半径自适应调整,增强后期局部搜索能力;同时利用分布式信息共享机制避免算法早熟并引入变异火花增强种群多样性。利用标准测试集进行验证后,结果表明该算法在求解带时间窗车辆路径问题时不仅具有可行性和有效性,并且收敛速度快、搜索质量高。     

Airline planning and scheduling: Models and solution methodologies

The airline industry is a representative industry with high cost and low profitability. Therefore, airlines should carefully plan their schedules to ensure that overall profit is maximized. We review the literature on airline planning and scheduling and focus on mathematical formulations and solution methodologies. Our research framework is anchored on three major problems in the airline scheduling, namely, fleet assignment, aircraft routing, and crew scheduling. General formulation, widely used solution approaches, and important extensions are presented for each problem and integrated problems. We conclude the review by identifying promising areas for further research.     

Heuristic algorithms for a three-dimensional loading capacitated vehicle routing problem in a carrier

In this paper, we present heuristic algorithms for a three-dimensional loading capacitated vehicle routing problem arising in a real-world situation. In this problem, customers make requests of goods, which are packed in a sortment of boxes. The objective is to find minimum cost delivery routes for a set of identical vehicles that, departing from a depot, visit all customers only once and return to the depot. Apart of the usual 3D container loading constraints which ensure that the boxes are packed completely inside the vehicles and that the boxes do not overlap each other in each vehicle, the problem also takes into account constraints related to the vertical stability of the cargo and multi-drop situations. The algorithms are based on the combination of classical heuristics from both vehicle routing and container loading literatures, as well as two metaheuristic strategies, and their use in more elaborate procedures. Although these approaches cannot assure optimal solutions for the respective problems, they are relatively simple, fast enough to solve real instances, flexible enough to include other practical considerations, and normally assure relatively good solutions in acceptable computational times in practice. The approaches are also sufficiently generic to be embedded with algorithms other than those considered in this study, as well as they can be easily adapted to consider other practical constraints, such as the load bearing strength of the boxes, time windows and pickups and deliveries. Computational tests were performed with these methods considering instances based on the vehicle routing literature and actual customers’ orders, as well as instances based on a real-world situation of a Brazilian carrier. The results show that the heuristics are able to produce relatively good solutions for real instances with hundreds of customers and thousands of boxes.     

An adaptive local search algorithm for vehicle routing problem with simultaneous and mixed pickups and deliveries

The Vehicle Routing Problem with Simultaneous Pickup and Delivery (VRPSPD) is an extension to the classical Vehicle Routing Problem (VRP), where customers may both receive and send goods simultaneously. The Vehicle Routing Problem with Mixed Pickup and Delivery (VRPMPD) differs from the VRPSPD in that the customers may have either pickup or delivery demand. However, the solution approaches proposed for the VRPSPD can be directly applied to the VRPMPD. In this study, an adaptive local search solution approach is developed for both the VRPSPD and the VRPMPD, which hybridizes a Simulated Annealing inspired algorithm with Variable Neighborhood Descent. The algorithm uses an adaptive threshold function that makes the algorithm self-tuning. The proposed approach is tested on well-known VRPSPD and VRPMPD benchmark instances derived from the literature. The computational results indicate that the proposed algorithm is effective in solving the problems in reasonable computation time.