GREEDY NON-DOMINATED SORTING IN GENETIC ALGORITHM-ⅡFOR VEHICLE ROUTING PROBLEM IN DISTRIBUTION

Vehicle routing problem in distribution （VRPD） is a widely used type of vehicle routing problem （VRP）, which has been proved as NP-Hard, and it is usually modeled as single objective optimization problem when modeling. For multi-objective optimization model, most researches consider two objectives. A multi-objective mathematical model for VRP is proposed, which considers the number of vehicles used, the length of route and the time arrived at each client. Genetic algorithm is one of the most widely used algorithms to solve VRP. As a type of genetic algorithm （GA）, non-dominated sorting in genetic algorithm-Ⅱ （NSGA-Ⅱ） also suffers from premature convergence and enclosure competition. In order to avoid these kinds of shortage, a greedy NSGA-Ⅱ （GNSGA-Ⅱ） is proposed for VRP problem. Greedy algorithm is implemented in generating the initial population, cross-over and mutation. All these procedures ensure that NSGA-Ⅱ is prevented from premature convergence and refine the performance of NSGA-Ⅱ at each step. In the distribution problem of a distribution center in Michigan, US, the GNSGA-Ⅱ is compared with NSGA-Ⅱ. As a result, the GNSGA-Ⅱ is the most efficient one and can get the most optimized solution to VRP problem. Also, in GNSGA-Ⅱ, premature convergence is better avoided and search efficiency has been improved sharply.

Comparative Study of Proactive, Reactive and Geographical MANET Routing Protocols

Mobile Adhoc Network (MANET) is defined as a combination of mobile nodes that lack a fixed infrastructure and is quickly deployable under any circumstances. These nodes have self-aware architecture and are able to move in multiple directions, which renders it dynamic topology. Its dynamicity makes routing in MANET rather challenging compared to fixed wired networks. This paper aims to perform a comparative study on the three categories of MANET routing protocol by comparing their characteristics and operations, as well as their strength and weaknesses.

Weak Greedy Routing over Graph Embedding for Wireless Sensor Networks

In this paper we classify the greedy routing in sensor networks into two categories, strong greedy routing and weak greedy routing. Most existing work mainly focuses on weak greedy routing over geographic location network or strong greedy routing over greedy embedding network. It is a difficult job and needs much cost to obtain geographic location or greedy embedding of the network. We propose a light-weight Tree-based graph embedding (TGE) for sensor networks. Over the TGE, we design a weak greedy routing protocol, TGR. TGR can archive good performance on path stretch factor and load balance factor.

Intelligent Greedy Perimeter Stateless Routing Scheme for Unmanned Aerial Vehicles

The dynamic behavior,rapid mobility,abrupt changes in network topology,and numerous other flying constraints in unmanned aerial vehicle(UAV)networks make the design of a routing protocol a challenging task.The data routing for communication between UAVs faces numerous challenges,such as low link quality,data loss,and routing path failure.This work proposes greedy perimeter stateless routing(GPSR)based design and implementation of a new adaptive communication routing protocol technique for UAVs,allowing multiple UAVs to communicate more effectively with each other in a group.Close imitation of the real environment is accomplished by considering UAVs’three-dimensional(3D)mobility in the simulations.The performance of the proposed intelligent greedy perimeter stateless routing(IGPSR)scheme has been evaluated based on end-to-end(E2E)delay,network throughput,and data loss ratio.The adapted scheme displayed on average 40%better results.The scenario has been implemented holistically on the network simulator software NS-3.

物流配送(集货)中运输车辆优化的Greedy Sweep算法

运输在物流中具有十分重要的地位 ,同时运输车辆优化的问题是物流决策中的关键所在 .目前 ,运输工具购买及维护的昂贵使得物流管理的决策者在制定行车路线时 ,总是希望充分利用运输工具的运力 .就物流管理系统中运输工具利用和行车路线优化制定问题 ,提出利用贪婪思想的扫描法 (TheSweepMethod)得到此问题的满意解 ,此算法简洁实用 。

Location-Based Routing Protocols for Wireless Sensor Networks: A Survey

Recently, location-based routings in wireless sensor networks (WSNs) are attracting a lot of interest in the research community, especially because of its scalability. In location-based routing, the network size is scalable without increasing the signalling overhead as routing decisions are inherently localized. Here, each node is aware of its position in the network through some positioning device like GPS and uses this information in the routing mechanism. In this paper, we first discuss the basics of WSNs including the architecture of the network, energy consumption for the components of a typical sensor node, and draw a detailed picture of classification of location-based routing protocols. Then, we present a systematic and comprehensive taxonomy of location-based routing protocols, mostly for sensor networks. All the schemes are subsequently discussed in depth. Finally, we conclude the paper with some insights on potential research directions for location-based routing in WSNs.

Geometric Name Routing for ICN in Dynamic World

A new paradigm of scalable routing for ICN is to combine a geometric routing scheme with a Distributed Hash Table. However, for most routing schemes in this paradigm, when a node joins or leaves, large numbers of nodes, even the whole topology, need to be re-embedded, and a great number of contents need to be re-registered. In this paper, we propose D-Griffin, a geometric routing scheme on flat names for dynamic topologies. D-Griffin provides two advantages. First, it avoids re-embedding the topology by using an online greedy embedding scheme and a void handling greedy forwarding scheme. Second, it decreases the number of re-registrations by using a name mapping scheme with a tradeoff between topology independence and load balancing. Theoretical and experimental analyses show that D-Griffin provides guaranteed content lookup, low description complexity, low path stretch, scalable routing update, and acceptable load balancing.

A Trusted Routing Protocol Based on GeoDTN＋Nav in VANET

Because the node of vehicular ad-hoc networks has the characteristics of high mobility and encounter temporary, a trust management between the nodes in the routing process becomes more difficult. To solve this problem, this paper proposes a new trusted routing protocol in VANET based on GeoDTN＋Nav by using trust management model of Bayesian and the three opportunistic routing forwarding models, which includes four steps of the routing initialization, the routing discovery, the trusted routing establishment and the routing deletion. The proposed protocol not only improves the security of routing, but also has the lower time complexity. Besides, experimental results and analysis show that the protocol has achieved good performance in the removal ratio of malicious nodes, correct reception ratio of packet and the message payload.

Proportional Fairness Based Energy Efficient Routing in Wireless Sensor Network

Wireless Sensor Network (WSN) is an independent device that comprises a discrete collection of Sensor Nodes (SN) to sense environmental positions,device monitoring, and collection of information. Due to limited energy resourcesavailable at SN, the primary issue is to present an energy-efficient framework andconserve the energy while constructing a route path along with each sensor node.However, many energy-efficient techniques focused drastically on energy harvesting and reduced energy consumption but failed to support energy-efficient routingwith minimal energy consumption in WSN. This paper presents an energy-efficientrouting system called Energy-aware Proportional Fairness Multi-user Routing(EPFMR) framework in WSN. EPFMR is deployed in the WSN environment usingthe instance time. The request time sent for the route discovery is the foremost stepdesigned in the EPFMR framework to reduce the energy consumption rate. Theproportional fairness routing in WSN selects the best route path for the packet flowbased on the relationship between the periods of requests between different SN.Route path discovered for packet flow also measure energy on multi-user route pathusing the Greedy Instance Fair Method (GIFM). The GIFM in EPFMR developsnode dependent energy-efficient localized route path, improving the throughput.The energy-aware framework maximizes the throughput rate and performs experimental evaluation on factors such as energy consumption rate during routing,Throughput, RST, node density and average energy per packet in WSN. The RouteSearching Time (RST) is reduced using the Boltzmann Distribution (BD), and as aresult, the energy is minimized on multi-user WSN. Finally, GIFM applies aninstance time difference-based route searching on WSN to attain an optimal energyminimization system. Experimental analysis shows that the EPFMR framework canreduce the RST by 23.47% and improve the throughput by 6.79% compared withthe state-of-the-art works.

Improving Reactive Ad Hoc Routing Performance by Geographic Route Length

In order to help reactive ad hoc routing protocols select better-performance routes, a novel metric named geographic route length （GRL） is proposed. The relationship between GRL metric and routing performance is analyzed in detail. Combined with hop metric, GRL is applied into the original ad hoe on-demand distance vector （AODV） to demonstrate its effectiveness. Simulation experiments have shown that GRL can effectively reduce packet delay and route discovery frequency, thus can improve reactive ad hoc routing performance.

An ellipse-guided routing algorithm in wireless sensor networks

In wireless sensor networks,sensor nodes are deployed to collect data,perform calculations,and forward information to either other nodes or sink nodes.Recently,geographic routing has become extremely popular because it only requires the locations of sensor nodes and is very efficient.However,the local minimum phenomenon,which hinders greedy forwarding,is a major problem in geographic routing.This phenomenon is attributed to an area called a hole that lacks active sensors,which either prevents the packet from being forwarded to a destination node or produces a long detour path.In order to solve the hole problem,mechanisms to detect holes and determine landmark nodes have been proposed.Based on the proposed mechanisms,landmark-based routing was developed in which the source node first sends a packet to the landmark node,and the landmark node then sends the packet to the destination.However,this approach often creates a constant node sequence,causing nodes that perform routing tasks to quickly run out of energy,thus producing larger holes.In this paper,a new approach is proposed in which two virtual ellipses are created with the source,landmark,and destination nodes.Then guide the forwarding along the virtual ellipses.Furthermore,a recursive algorithm is designed to ensure a shortcut even if there are multiple holes or a hole has multiple landmarks.Thus,the proposed approach improves both geographic routing and energy efficiency routing.Simulation experiments show that the proposed approach increases the battery life of sensor nodes,lowers the end-to-end delay,and generates a short path.

Potential field based hole detour routing algorithm in wireless sensor networks

The current geographic routing protocols arise data congestion if a multi-flow bypasses a hole simultaneously and excessive energy consumption of hole boundary nodes because these protocols tend to route data packets along the boundaries of void areas （holes） by perimeter routing scheme.This scheme possibly enlarges the holes phenomenon （called hole diffusion problem） and shortens the life span of the network. A novel geographical routing algorithm based on a potential field approach （PFA） is proposed to deal with multiple holes scenario and restrict data to forward near boundary of a hole. That is, data packets are attracted to its sink and are repulsed away from the hole （s）. Simulation results show that PFA is superior to other protocols in terms of packet delivery ratio, network lifetime.

A Robust Emergency Messages Routing Scheme for Urban VANETs

Vehicular ad-hoc networks(VANETs)play an essential role in enhancing transport infrastructure by making vehicles intelligent and proficient in preventing traffic fatalities.Direction-based greedy protocols pick the next route vehicle for transmitting emergency messages(EMs)depending upon the present location of adjacent vehicles towards sink vehicles by using an optimal uni-directional road traffic approach.Nevertheless,such protocols suffer performance degradation by ignoring the moving directions of vehicles in bi-directional road traffic where topological changes happen continuously.Due to the high number of vehicles,it is essential to broadcast EMs to all vehicles to prevent traffic delays and collisions.A cluster-based EM transmitting technique is proposed in this paper.For urban VANETs,this paper pioneers the clustering of bi-directional road traffic for robust and efficient routing of EMs.In this regard,this paper introduces a routing protocol,namely,the bi-directional urban routing protocol(BURP).In addition to the paths and relative locations of vehicles,BURP takes account of the distance parameter by using the Hamming distance function to determine the direction ofmotion of vehicles and communicates EMs through the cluster head(CH).Amodified k-medoids algorithm is presented for the clustering of bi-directional road traffic.A median method is presented for selecting CH to ensure the longrunning of a cluster.Simulation results show that BURP provides enhanced throughput,a maximized packet delivery ratio,low energy consumption,and network delay relative to eminent routing protocols.

Multipath Grid-Based Enabled Geographic Routing for Wireless Sensor Networks

This work proposes an efficient disjoint multipath geographic routing algorithm for dense wireless sensor networks (WSN), called Multipath Grid-based Enabled Geographic Routing (MGEGR). The proposed algorithm relies on the construction of a 2-D logical grid in the geographical region of deployment. The objective of the proposed scheme is to determine optimal or near-optimal (within a defined constant) multiple disjoint paths (multipath) from a source node to the sink, in order to enhance the reliability of the network. The determined multiple disjoint paths would be used by the source node in a round-robin way to balance the traffic across the disjoint paths, and to avoid discovered paths with cell holes. The proposed scheme limits the use of broadcasting to the process of gateway election within each cell, and the process of maintaining the table of neighbors of each gateway. Our simulation results show the effectiveness and scalability of our routing scheme with increased network size compared to on-demand routing protocols.

A Void Avoidance Scheme for Grid-Based Multipath Routing in Underwater Wireless Sensor Networks

This work proposes a geographic routing protocol for UWSNs based on the construction of a 3D virtual grid structure, called Void-Avoidance Grid-based Multipath Position-based Routing (VA-GMPR). It consists of two main components, the multipath routing scheme and the grid-based void avoidance (GVA) mechanism for handling routing holes. The multipath routing scheme adopts node-disjoint routes from the source to the sink in order to enhance network reliability and load balancing. While the GVA mechanism handles the problem of holes in 3D virtual grid structure based on three techniques: Hole bypass, path diversion, and path backtracking. The performance evaluation of the VA-GMPR protocol was compared to a recently proposed grid-based routing protocol for UWSNs, called Energy-efficient Multipath Geographic Grid-based Routing (EMGGR). The results showed that the VA-GMPR protocol outperformed the EMGGR protocol in terms of packet delivery ratio, and end-to end-delay. However, the results also showed that the VA-GMPR protocol exhibited higher energy consumption compared to EMGGR.

Google Earth-based dynamic visualization system for storm surge flood routing

To describe the dynamic process of flood routing intuitively and realistically when storm surge disaster occurs,a method for ArcGIS data and Google Earth(GE) data integration is proposed,which realizes the importing and integrating of basic geographic information into GE. Based on SketchUp and AutoCAD software,threedimension(3D) visualization of seawall and other tidal defense structures is achieved. By employing Microsoft Foundation Class Library(MFC),the related system modules and storm surge flood routing dynamic visualization system are developed. Therefore,dynamic visualization of flood routing process and interactive query of submerged area and inundated depth are implemented. A practical application case study of Tianjin Binhai New Area provides decision-making support for coastal seawall planning and storm surge disaster prevention and reduction.

A Hybrid Genetic Algorithm for Vehicle Routing Problem with Complex Constraints

Most research on the Vehicle Routing Problem （VRP） is focused on standard conditions, which is not suitable for specific cases. A Hybrid Genetic Algorithm is proposed to solve a Vehicle Routing Problem （VRP） with complex side constraints. A novel coding method is designed especially for side constraints. A greedy algorithm combined with a random algorithm is introduced to enable the diversity of the initial population, as well as a local optimization algorithm employed to improve the searching efficiency. In order to evaluate the performance, this mechanism has been implemented in an oil distribution center, the experimental and executing results show that the near global optimal solution can be easily and quickly obtained by this method, and the solution is definitely satisfactory in the VRP application.

A Contention-Based MAC and Routing Protocol for Wireless Sensor Network

Advance development of wireless technologies and micro-sensor systems have enabled Wireless Sensor Network (WSN) to emerge as a leading solution in many crucial sensor-based applications. WSN deploys numerous resource-constrained sensor nodes which have limited power supply, memory and computation capability in a harsh environment. Inefficient routing strategy results in degraded network performance in terms of reliability, latency and energy efficiency. In this paper, a cross-layer design, Contention-based MAC and Routing protocol is proposed, termed Contention/SNIR-Based Forwarding (CSBF) protocol. CSBF utilizes the geographical information of sensor nodes to effectively guide the routing direction towards destination node, thereby enhancing reliability. Furthermore, Signal-to-Noise-plus-Interference Ratio (SNIR) metric is used as a routing parameter to guarantee high quality link for data transmission. A Contention-Winner Relay scheme is utilized to reduce the delays caused by the contention procedure. Energy efficiency is also improved by introducing sleep mode technique in CSBF. The simulation work is carried out via OMNeT++ network simulator. The performance of CSBF is compared with other existing routing protocols such as AODV and DSDV in terms of packet delivery ratio (PDR), average end-to-end (ETE) delay and energy consumption per packet. Simulation results highlight that CSBF outperforms AODV and DSDV protocols in respect of PDR and energy efficiency. CSBF also has the most consistent overall network performance.

求解带容量约束车辆路径问题的改进遗传算法

为解决传统遗传算法求解带容量约束的车辆路径问题时收敛速度慢和局部搜索能力差的问题,对传统遗传算法提出一种改进策略。使用基于贪婪策略的启发式交叉算子加强算法接近最优解的能力,加快算法收敛速度,在变异操作中,引入最近邻搜索算子,缩小基因变异范围,使用单点局部插入算子提高算法的局部优化能力。采用精英选择和轮盘赌法结合的选择策略,保持种群多样性以加强算法的全局搜索能力。实例计算测试表明,与传统遗传算法相比,所提算法求解平均偏差降低了70.25%,求解时间减少了87.41%;与ALNS和AGGWOA算法相比,有更高的求解质量和更好的稳定性。

考虑暴雨灾害动态影响的城市应急车辆救援路径优化研究

近年来,极端天气事件发生频次不断增加,强度不断加大,其中,由暴雨引发的城市内涝导致交通应急事件发生概率进一步增大。为提升暴雨灾害下应急救援响应速度,本文开展应急车辆救援路径优化研究。以通行时间最短为目标,考虑路面积水对车辆通行速度的动态影响,构建应急车辆救援路径优化模型,提出动态最短路径优化算法求解模型。选取上海市长宁区东北部作为研究区域,根据SWMM(Storm Water Management Model)模拟得到的50年一遇暴雨条件下城市道路路面的积水情况,设定应急救援场景,求解应急救援路径。通过本文提出算法求解得到的路径与传统静态最短路径算法求解结果对比可知,通行用时同比减少了25.42%。同时,考虑应急物资储备情况分配应急救援任务,扩展了算法的应用场景,形成可靠和高效的应急响应方案,可为提升暴雨灾害下应急响应效率提供参考。