检索结果-内蒙古大学图书馆

Clique Inequalities Applied to the Vehicle Routing Problem with Time Windows

INFOR 2010年第1期48卷 53-67页

作者： Spoorendonk, Simon Desaulniers, Guy Tech Univ Denmark DTU Management Engn DK-2800 Lyngby Denmark Ecole Polytech Montreal PQ H3C 3A7 Canada Gerad Dept Math & Ind Engn Montreal PQ H3C 3A7 Canada

This work presents an exact branch-cut-and-price algorithm for the vehicle routing problem with time windows (VRPTW) where the well-known clique inequalities are used as cutting planes defined on the set partitioning master problem variables. It shows how these cutting planes affect the dominance criterion applied in the pricing algorithm, which is a labeling algorithm for solving resource-constrained elementary shortest path problems. The idea of using cutting planes defined on the master problem variables for the VRPTW has been recently developed: Chvatal-Gomory rank-1 cuts were applied. However, to our knowledge, this is a first attempt at incorporating for the VRPTW a set of valid inequalities specialized for the set partitioning polytope. Computational results show that the use of clique inequalities improves the lower bound at the root node of the search tree and reduces the number of nodes in this tree.

关键词： Studies Routing shortest path algorithms Branch & bound algorithms

来源：评论

学校读者我要写书评

暂无评论

Load Balancing Routing with Bounded Stretch

引用

EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2010年第1期2010卷 623706-623706页

作者： Li, Fan Chen, Siyuan Wang, Yu Univ N Carolina Dept Comp Sci Coll Comp & Informat Charlotte NC 28223 USA Beijing Inst Technol Sch Comp Sci Beijing Lab Intelligent Informat Technol Beijing 100081 Peoples R China

Routing in wireless networks has been heavily studied in the last decade. Many routing protocols are based on classic shortest path algorithms. However, shortest path-based routing protocols suffer from uneven load distribution in the network, such as crowed center effect where the center nodes have more load than the nodes in the periphery. Aiming to balance the load, we propose a novel routing method, called Circular Sailing Routing (CSR), which can distribute the traffic more evenly in the network. The proposed method first maps the network onto a sphere via a simple stereographic projection, and then the route decision is made by a newly defined "circular distance" on the sphere instead of the Euclidean distance in the plane. We theoretically prove that for a network, the distance traveled by the packets using CSR is no more than a small constant factor of the minimum (the distance of the shortest path). We also extend CSR to a localized version, Localized CSR, by modifying greedy routing without any additional communication overhead. In addition, we investigate how to design CSR routing for 3D networks. For all proposed methods, we conduct extensive simulations to study their performances and compare them with global shortest path routing or greedy routing in 2D and 3D wireless networks.

关键词： Load balancing Spheres Euclidean distance Cheyne-Stokes Respiration shortest path Ganglia shortest path algorithms Wireless networks Network routing shortest-path routing

来源：评论

学校读者我要写书评

暂无评论

A comparison of algorithms for origin-destination matrix generation on real road networks and an approximation approach

引用

COMPUTERS & INDUSTRIAL ENGINEERING 2009年第1期56卷 70-76页

作者： Kim, Byung-In Jeong, Sangwon POSTECH Adv Prod & Prod Technol Center Dept Ind & Management Engn Pohang 790084 Kyungbuk South Korea

This paper considers the generation of the origin-destination (OD) matrix, basic data in any vehicle routing or traveling salesman problem. An OD matrix must be generated by calculating the shortest paths between some nodes. Candidate methods for this are repetitive use of one-to-all shortest path algorithms such as Dijkstra's algorithm, use of all-to-all shortest path algorithms such as the Floyd-Warshall algorithm, and use of specifically designed some-to-some shortest path algorithms. This paper compares the performance of several shortest path algorithms in computing OD matrices on real road networks. Dijkstra's algorithm with approximate bucket data structure performed the best for most of the networks tested. This paper also proposes a grouping-based algorithm for OD matrix generation. Although it is an approximation approach, it has several good characteristics: it can find the exact shortest distances for most OD pairs;it guarantees that all the calculated shortest path distance values have corresponding paths;the deviation of any distance from the corresponding true shortest distance is small;and its computation time is short. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： Origin-destination matrix shortest path algorithms Real road networks Approximation algorithm

来源：评论

学校读者我要写书评

暂无评论

Sequential Traffic Flow Optimization with Tactical Flight Control Heuristics

引用

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2009年第3期32卷 810-820页

作者： Grabbe, Shon Sridhar, Banavar Mukherjee, Avijit NASA Ames Res Ctr Automat Concepts Res Branch Moffett Field CA 94035 USA NASA Ames Res Ctr Aviat Syst Div Moffett Field CA 94035 USA Univ Calif Santa Cruz Moffett Field CA 94035 USA

A sequential optimization method is applied to manage air traffic flow under uncertainty in airspace capacity and demand. To support its testing, a decision support system is developed by integrating a deterministic integer programming model for assigning delays to aircraft under en route capacity constraints with a fast-time simulation environment to reactively account for system uncertainties. To reduce computational complexity, the model assigns only departure controls, and a tactical control loop consisting of a shortest-path routing algorithm and an airbornedelay algorithm refines the strategic plan to keep flights from deviating into capacity-constrained airspace. This integrated approach was used to conduct 32 six-hour fast-time simulation experiments to explore variations in the number and severity of departure controls, tactical reroutes, and airborne-delay controls. These experiments highlighted a fundamental difference in the manner in which weather translation is performed at the strategic and tactical levels. Although tactical weather translation explicitly accounts for the direct impact of weather on individual flights, strategic weather translation, which is accomplished by calculating a reduced capacity fora region of airspace such as a sector, typically fails to account for these flow-based impacts. Finally, an initial validation of the rerouting algorithm, which was the dominant control strategy for avoiding en route weather in the experiments, indicates that the algorithm is able to generate reroutes that are, on average, shorter than operationally flown weather-avoidance routes, when regions of airspace that flights are likely to avoid are identified using the convective-weather-avoidance model.

关键词： Flight Control Airspace Decision Support System Enhanced Traffic Management System Strategic Departure Control Model Air Traffic Control System Command Center Dallas/Fort Worth International Airport shortest path algorithms Federal Aviation Administration Fuel Consumption

来源：评论

学校读者我要写书评

暂无评论

Finding shortest paths on real road networks: the case for A*

引用

INTERNATIONAL JOURNAL OF GEOGRAPHICAL INFORMATION SCIENCE 2009年第4期23卷 531-543页

作者： Zeng, W. Church, R. L. Univ Calif Santa Barbara Dept Geog Santa Barbara CA 93106 USA China Univ Geosci Fac Informat Engn Wuhan 430074 Peoples R China

The problem of identifying the shortest path along a road network is a fundamental problem in network analysis, ranging from route guidance in a navigation system to solving spatial allocation problems. Since this type of problem is solved so frequently, it is important to craft an approach that is as efficient as possible. Based upon past research, it is generally accepted that several efficient implementations of the Dijkstra algorithm are the fastest at optimally solving the 'one-to-one' shortest path problem (Cherkassky et al. 1996). We show that the most efficient state-of-the-art implementations of Dijkstra can be improved by taking advantage of network properties associated with GIS-sourced data. The results of this paper, derived from tests of different algorithmic approaches on real road networks, will be extremely valuable for application developers and researchers in the GIS community.

关键词： shortest path algorithms A* algorithm Transportation networks

来源：评论

学校读者我要写书评

暂无评论

CUDA Solutions for the SSSP Problem

CUDA Solutions for the SSSP Problem

引用

9th International Conference on Computational Science

作者： Martin, Pedro J. Torres, Roberto Gavilanes, Antonio Univ Complutense Madrid Dpto Sistemas Informat & Computatc E-28040 Madrid Spain

ISBN: (纸本)9783642019692

We present several algorithms that solve the single-source shortest-path problem using CUDA. We have run them on a database, composed of hundreds of large graphs represented by adjacency lists and adjacency matrices, achieving high speedups regarding a CPU implementation based on Fibonacci heaps. Concerning correctness, we outline why our solutions work, and show that a previous approach [10] is incorrect.

关键词： shortest path algorithms GPU CUDA

来源：评论

学校读者我要写书评

暂无评论

Minimizing mission risk in fuel-constrained unmanned aerial vehicle path planning

引用

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2008年第5期31卷 1497-1500页

作者： Oegren, Petter Winstrand, Maja Swedish Def Res Agcy Dept Autonomous Syst S-16490 Stockholm Sweden

ONE of the main reasons for using an unmanned aerial vehicle (UAV) instead of a manned aircraft is when the mission that needs to be carried out is very dangerous. In such cases, we believe that the risk of losing the vehicle should be made an explicit and important part of the mission planning. The mentioned risks can often be estimated on a small scale, using detailed simulation models, but the tools to propagate such estimates to the overall mission-planning level has been missing. In this paper, we propose one way to take such local risk estimates into account in the mission planning and, at the same time, make the tradeoffs against other path properties, such as fuel or time constraints, explicitly. First, we show how to rewrite the accumulated risk estimate into a form that matches the formulation of the so-called weight-constrained shortest-path problem (WCSPP). Then we approximately solve it using a series of regular shortest-path problems (SPP). These are, in turn, easily solved by standard algorithms such as Dijkstra's as described in [1] or D* [2].

关键词： UAV path Planning shortest path algorithms RADAR Autonomous Systems Electronic Warfare

来源：评论

学校读者我要写书评

暂无评论

Sparse matrix computations on manycore GPU's

Sparse matrix computations on manycore GPU's

引用

45th ACM/IEEE Design Automation Conference

作者： Garland, Michael NVIDIA Corp Santa Clara CA 95050 USA

ISBN: (纸本)9781605581156

Modem microprocessors are becoming increasingly parallel devices, and GPUs are at the leading edge of this trend. Designing parallel algorithms for manycore chips like the GPU can present interesting challenges, particularly for computations on sparse data structures. One particularly common example is the collection of sparse matrix solvers and combinatorial graph algorithms that form the core of many physical simulation techniques. Although seemingly irregular, these operations can often be implemented with data parallel operations that map very well to massively parallel processors.

关键词： parallel programming data-parallel algorithms GPU computing sparse matrix-vector multiplication shortest path algorithms

来源：评论

学校读者我要写书评

暂无评论

Sparse Matrix Computations on Manycore GPU's 08

Sparse Matrix Computations on Manycore GPU's

引用

45th ACM/IEEE Design Automation Conference, vol.1

作者： Michael Garland NVIDIA Corporation Santa Clara CA

ISBN: (纸本)9781605581156

Modern microprocessors are becoming increasingly parallel devices, and GPUs are at the leading edge of this trend. Designing parallel algorithms for manycore chips like the GPU can present interesting challenges, particularly for computations on sparse data structures. One particularly common example is the collection of sparse matrix solvers and combinatorial graph algorithms that form the core of many physical simulation techniques. Although seemingly irregular, these operations can often be implemented with data parallel operations that map very well to massively parallel processors.

关键词： algorithms Parallel programming Data-parallel algorithms GPU computing Sparse matrix-vector multiplication shortest path algorithms

来源：评论

学校读者我要写书评

暂无评论

Optimal cooperative reconnaissance using multiple vehicles

引用

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2007年第1期30卷 122-132页

作者： Ousingsawat, Jarurat Campbell, Mark E. Cornell Univ Sibley Sch Mech & Aerosp Engn Ithaca NY 14853 USA

A study on multivehicle trajectory planning for cooperative reconnaissance problems is presented. Specifically, this work develops understanding and insights into how vehicles cooperate in reconnaissance type missions in which target information is maximized. The performance metric used to guide the cooperation study is the amount of information, defined using the Fisher information matrix, that the sensing vehicles gather over their planned trajectory. A receding horizon optimal control formulation is developed and solved for trajectories that yield maximum information. High-risk zones and vehicle/terminal constraints are also are considered. Trends include the following: 1) vehicles with nonsymmetric sensors tend to triangulate as they get close to the target;2) vehicles tend to move toward stationary targets as quickly as possible;3) the addition of a third vehicle exhibits at least 50% less performance improvement than the addition of the second vehicle, and even less for nonsymmetric sensors.;4) optimization for multiple vehicles and targets is a strong function of target to target distances and sensor uncertainty symmetry;and 5) short planning horizons are preferable for moving targets.

关键词： Sensors Trajectory Optimization Vehicle Trajectories Lagrange Multipliers path Planning shortest path algorithms Boundary Value Problems Mixed Integer Linear Programming Control Optimization Kalman Filter

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：