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提出一种基于网络Voronoi面域图的最大覆盖选址模型及相应的粒子群优化方法,并应用于城市响应时间敏感型公共服务设施的空间优化。本文考虑设施功能沿交通网络辐射以及需求非均匀分布情形,对设施在网络连续空间上进行布局优化,选址模型采用网络Voronoi面域图划分布局设施的功能辐射域,以启发空间优化最小化重叠覆盖。模型同时顾及了设施利用率的最大化,规定设施对给定距离以内的需求实行的完全服务覆盖和对给定距离以外的需求实行随距离衰减的部分服务覆盖。本研究提出基于遗传机制和广义Voronoi图改进的粒子群算法以提高其空间优化性能,通过对南京市消防站最大覆盖空间优化实验表明,该研究取得了较为理想的结果,可应用于城市化区域应急设施最大覆盖空间优化。 相似文献
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通过分析可达的时空分布情况可以说明不同区域公共交通服务水平的差异,然而这种分析方法缺乏对公平的直接量化。针对传统交通可达指标无法反映时变公平和局部区域对全局公平的贡献问题,本文提出了一种基于可达计算的局部多模态的时空公平指标。可达计算考虑包括地面公交与地铁等多模态的乘车方式,并计算不同时刻可达值,利用相对变化的熵来衡量不同局部区域在时变情况下对整体的贡献率。通过对贡献率相同的区域进行聚类,可以直观地分析交通服务分布的公平变化。本文将指标用于武汉市公交网络,分析了地铁修建前后武汉市不同区域到达不同城市商圈的可达公平变化。试验结果表明,指标可以有效地反映不同时刻武汉市公共交通公平的时空分布情况。 相似文献
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一种顾及道路影响的点状要素注记自动配置模型 总被引：1，自引：0，他引：1
针对制图过程中点状要素数量巨大且分布密集的时候,传统注记配置方法无法兼顾解决注记压盖、歧义,同时减少时间耗费的问题,该文提出了一种基于图论的点状要素注记配置模型。该模型在考虑传统点状要素注记配置问题的同时,还可以附加考虑其他影响注记位置摆放的条件,并将其形式化表达为最大团问题;随后使用一种基于禁忌搜索策略的启发式算法来求解该最大团问题,从而得到注记配置问题的解;该模型有效地提高了注记配置问题的求解效率,较好地平衡了注记位置压盖和位置歧义的关系。最后,该文具体以沿道路分布的点状要素注记配置模式为例进行实验,证明了该注记自动配置模型可以有效地增强地图的可读性和美观性。 相似文献
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《武汉大学学报(信息科学版)》2010,(8)
基于对大坝监测资料预测模型时变性的要求,在模型LS参数求解过程中引入遗忘因子,提出了能够实现模型参数实时更新的IWRLS算法。在此基础上,为使预测模型体现物理含义的同时实现滤波操作,在Kalman滤波方程组中融入统计模型、ARMA等多种方法,由此建立了考虑白色观测噪声的时变Kalman预测模型。实例分析表明,时变Kalman模型拟合及预测精度均优于传统统计模型,为大坝监测资料的预测分析提供了新思路。 相似文献
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应急测绘中的无人机调度存在时空环境约束复杂、调度方案多样的特点,现有调度主要以人为经验判断为主,方案粗放不可靠,难以综合考虑应急过程中复杂多变的因素,结果的精准性与可靠性较低。为实现灾后应急测绘的快速响应,提出了一种无人机资源的快速调度方法,综合考虑应急测绘任务需求、优先级、时间窗、作业区域地理环境和无人机测绘资源能力等约束条件,构建了以任务成果收益效率最大化、任务完成率最大化以及调度风险最小化等为多优化目标的应急测绘无人机资源调度模型,并运用蚁群算法实现对模型的求解。实验结果验证了调度方法的有效性。 相似文献
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基于路网应急疏散问题的实际需求,提出以路径流量为决策变量,以疏散流量最大、疏散路线最短和可靠性最高为目标的多目标优化模型,综合考虑了应急疏散的时效性、经济性和安全性,并设计自适应小生境Pareto遗传算法对模型进行求解。以某地区实际路网为例进行模拟分析,验证了算法的有效性和可行性。 相似文献
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传统光学卫星国土观测覆盖评估建立在卫星对地理想覆盖的基础上,并未考虑卫星存储、星地数据传输、观测时长等物理量及观测区域气象因素对于覆盖性能的影响。本文针对光学遥感卫星的国土观测需求.建立国土观测有效覆盖能力评估指标体系,根据卫星数据存储能力、星地数据传输能力、卫星单圈最大观测时长、卫星观测太阳高度角等性能参数,提出了基于物理性能约束下的有效覆盖计算方法。根据气象台站历年气象数据,提出了气象约束因子的计算方法。综合考虑卫星物理性能约束与观测区域气象约束,计算光学遥感卫星对地观测有效覆盖能力。最后根据专家设计的光学遥感卫星国土观测有效覆盖能力评估指标权重,利用层次分析法(AHP)评估光学遥感卫星系统对于国土观测的需求满足程度。试验结果表明,本文方法对于国土观测有效覆盖的估算和评价结果更加精确,更接近于国土观测的实际应用需求,为对地观测有效覆盖能力评估提供了一种更为精确的可行方案。 相似文献
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动态交通信息服务是社会化特征显著的智能交通系统理念中的重要组成部分之一,也是提高基于位置服务可用性的核心所在。动态交通信息服务的实现,需要在实时交通信息获取与微观交通仿真技术的基础上,构造各种应用模型和算法,并与地理信息系统环境下的交通信息管理与发布平台相结合,提供满足公众需求的信息服务,为公众出行、交通管理、物流运输等应用提供有效支持。目前业界存在几十种微观交通仿真模型和对应开发的微观交通仿真平台。这些模型和平台有着各自不同的特性,对地理信息系统的支持能力也存在很大差异。本文分析了SimTraffic、CORSim、VisSim、Paramics、AIMSUN、MITSimLab和TransModeler等7种几种业界成熟的微观交通仿真平台的技术特性,评价了它们对地理信息系统的支持能力,可为动态交通信息服务应用的研发提供有效参考。 相似文献
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针对青岛市中心城区交通网络建设不完善的问题,研究了该区域路网的综合可达性,并提出了相应的解决方案。基于GIS平台,建立了青岛市中心城区路网模型;选取最小阻抗(时间和距离)、交叉口服务指数、路网密度和路网连通度作为关键评价指标,分别从路网距离关系、路网结构合理性、路网密度和路网发育程度4个方面分析了该区域的路网可达性;在此基础上,建立了青岛市中心城区路网综合评价模型。研究结果表明,该区域的路网以多中心多圈层形式分布,整体可达性良好;西南区域路网密度低,南部外围区域机动性差,南部地区可达性较差,应不断加强该地区的基础设施与路网建设。 相似文献
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The quick response of civil authorities after a major disaster event in an urban area is essential for the reduction of damages
and impacts to human lives. One of the first critical problems to be solved at the very early stages of response is the optimum
management of emergency vehicles and real time knowledge of the accessibility of the road network. In this article the concept
of using a number of emergency vehicles as sensors for monitoring the traffic conditions in an urban area after a major disaster
event is described. The fleet management system used for this taks is working with ral time DGPS. The system makes use of
existing vehicle fleets in the urban area, rapidly collecting data and covering the whole road network. It records travel
times with the help of the GPS system for every road segment driven through by each vehicle sensor, thus providing a digital
time database from which traffic parameters can be also computed. It can be used for real time monitoring of traffic conditions
under disaster or emergency situations where all the previously available data become invalid or unreliable. ? 2002 Wiley
Periodicals, Inc. 相似文献
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The network K‐function in context: examining the effects of network structure on the network K‐function 
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下载免费PDF全文 The flaws of using traditional planar point‐pattern analysis techniques with network constrained points have been thoroughly explored in the literature. Because of this, new network‐based measures have been introduced for their planar analogues, including the network based K‐function. These new measures involve the calculation of network distances between point events rather than traditional Euclidean distances. Some have suggested that the underlying structure of a network, such as whether it includes directional constraints or speed limits, may be considered when applying these methods. How different network structures might affect the results of the network spatial statistics is not well understood. This article examines the results of network K‐functions when taking into consideration network distances for three different types of networks: the original road network, topologically correct networks, and directionally constrained networks. For this aim, four scenarios using road networks from Tampa, Florida and New York City, New York were used to test how network constraints affected the network K‐function. Depending on which network is under consideration, the underlying network structure could impact the interpretation. In particular, directional constraints showed reduced clustering across the different scenarios. Caution should be used when selecting the road network, and constraints, for a network K‐function analysis. 相似文献
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针对车载导航、地图网站等应用中路网要素之间交通关系维护的难题,提出一种支持路网要素交通关系自动化的智能过程模型,将路网要素交通关系自动化过程理解为由路网要素间的空间和语义关系、规则集和控制系统组成的产生式系统.该产生式系统可在路网要素空间和语义信息基础上,通过定义可扩展的交通关系规则集,自动化地生成符合应用需求的路网要素间的交通关系.此外,在该产生式系统中引入触发器概念监控和响应几何网络及其交通关系规则集的变更,实时更新逻辑网络中的连通关系信息,实现几何网络、规则集和逻辑网络三者的一致性.同时,提出路网要素交通关系处理的控制策略和关键流程,并对该智能网络模型的有效性进行了验证.Abstract： Maintaining the traffic connectivity relations between road features has always been a time consuming task for in-vehicle navigation, map website, and other traveling service related applications. Such a task has been commonly conducted artificially and inevitably inefficient, yet makes data quality control difficult. Considering the intrinsic rules of traffic connectivity formed by the geometrical structures, spatial and semantic relationships between road features in city road networks, an intelligent processing model is set forward in this paper for traffic connectivity automation. It is argued that traffic connectivity automation between road features is fundamentally a production system composed of the spatial and semantic relations between road features, connectivity rules and control system. With the implementation of an extendable connectivity rule set, the traffic connectivity relations between road network features are built automatically based on the spatial and semantic information of road network. The trigger concept is adopted to monitor and respond the changes in geometrical network and connectivity rules, and then dynamically updates the traffic connectivity between road network features in logical network so as to guarantee the consistence between geometrical network, connectivity rules and logical network. A series of control strategies and a conducting engine are developed to maintain the traffic connectivity relations. A case study conducted on a real road network verifies the effects of the proposed intelligent model. 相似文献
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Alternatives to current GPS-RTK services and some implications for CORS infrastructure and operations 总被引：1，自引：1，他引：1
Chris Rizos 《GPS Solutions》2007,11(3):151-158
The justification for the establishment of CORS networks was initially in support of geodesy and other geoscientific applications at the global and regional level. However, increasingly GPS CORS network operators have sought ways of making their network infrastructure the basis of a profitable business. This has arisen with the introduction of real-time centimeter-level accuracy services, carrier phase-based modes of operation generally referred to as GPS-RTK (real-time kinematic). One approach is to try to recruit a core group of users who are prepared to pay for the GPS-RTK services. But this is only feasible if the number of users, and the fees that are charged, are sufficient to generate a reasonable return-on-investment (ROI). This ROI (or at the very least “cost-recovery”) is important for many network operators in order that they may provide for the maintenance and upgrade of the CORS infrastructure. On the other hand, there are those who advocate that there is no need to recoup CORS investment, that the installed GPS receivers should be seen as public infrastructure in a similar manner to roads, bridges, etc. This paper discusses some new business and operational models for GPS-RTK services. These include models for the establishment and operation of CORS infrastructure, service provision, business cases, and options for value-added services beyond the standard GPS-RTK service. One concept is based on a “client–server” model. Currently GPS-RTK service providers have no control over the quality of the results computed by users. This makes it difficult for them to justify charging for their services. What if instead of broadcasting RTK corrections and placing the onus of obtaining a final solution on the user and his equipment, the user’s coordinates are determined by the service provider? Putting the computational effort on the server side will justify more easily the charging of users for a value-added product: an accurate and quality assured coordinate in the local reference frame. This paper describes the client–server concept as well as possible business models that may underpin such a service model. These models include some derived from mobile telephony and service/hospitality businesses. Furthermore, with the projected proliferation of independent, competitive GPS-RTK services, the concept of a GPS data or service “broker” is worth exploring. 相似文献
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城市交通迅速发展,道路网络呈现出空间结构复杂、数据量大、时效性强等特点。本文讨论了传统路网模型的特点,顾及道路的信息完整性、数据冗余性、管理高效性3个指标,研究了以道路实体为基本元素的路网模型;运用面向对象技术对路网模型进行了数据建模,并通过动态交通信息更新机制对路网的动态属性进行管理;构建了城市道路实体化实验系统,验证了该模型的有效性和可行性。 相似文献
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等时线模型支持下的路网可达性分析 总被引：1，自引：0，他引：1
等时线是道路网中参考于某特定点位的系列时间可达性的可视化表达,其生成需要分析道路网络特性及通行状况,其形态可以反映可达性规律。本文对等时线进行了定义、特性分析及生成方法研究;类比水滴沿木板的纹理扩散的过程,提出水流扩展算法生成等时线,在网络栅格化模型的基础上,考虑等时线扩展独特的约束条件,如道路状况、移动条件及时间分段等获得可达性扩展路径,通过扩展凸包和角平分线移位生成等时线。该算法基于场论思想,可以针对网络空间中任意感兴趣部分灵活负载约束条件,方便生成实时等时线;类比等高线表示地貌特征,对基于以上构建机制生成的等时线的排列、疏密、弯曲形式、弯曲方向及延伸方向等进行分析,发现空间可达性规律。 相似文献
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Tijs Neutens Nico Van de Weghe Frank Witlox Philippe De Maeyer 《Journal of Geographical Systems》2008,10(1):89-107
Time-geographic concepts are effective tools for the geovisualization of human activity patterns and to assess individual
accessibility. In their traditional form, however, time-geographic concepts assume uniform travel velocities in an isotropic
and homogeneous space. Because transportation systems confine travellers to links of road and rail networks with time-varying
flows, these premises are typically unsatisfied in real-world situations. This paper provides an innovative approach to ameliorate
the realism and applicability of space–time prisms by developing new three-dimensional space–time objects. Three-dimensional
solid models which account for non-uniform movement are discussed, and their usefulness is assessed and illustrated by means
of an example.
相似文献
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The emergence of the Sensor Web has paved the way for a new set of innovative software applications that exploit the enhanced availability of real‐time information. This article describes one such application built from Sensor Web components that aggregates GPS track data from a fleet of vehicles to provide an overview of road traffic congestion at the city scale. The application embodies a Service Oriented Architecture; web service components are used to archive and pre‐process incoming sensor observations, to encapsulate a horizontally partitioned spatial database that performs geoprocessing, and to disseminate results to client applications. Our results confirm that floating car data can provide an accurate depiction of current road traffic conditions. The presented solution uses Open Geospatial Consortium web services where possible and serves to highlight the difficulties inherent in achieving horizontal database scalability in sensor based geoprocessing systems. 相似文献