Exploring the Knowledge Dynamics Associated with Coastal Adaptation Planning

Scientific projections for climate change induced sea-level-rise highlight current and potential future consequences for low lying coastal areas. In response considerable attention has been directed toward the task of coastal adaptation planning. Experience to date indicates that adaptation planning is more complex and contested than anticipated. We argue that this is partly due to the constrained way adaptation planning is conceptualized, whereby limited attention is directed toward understanding coastal adaptation planning as a site of complex and contested knowledge dynamics. Consequently, we use a knowledge systems perspective to explore coastal adaptation planning in order to highlight some of the knowledge exchange dynamics involved. In doing so we draw on views expressed in semi-structured interviews with a diverse range of stakeholders with an interest in coastal management in Victoria, Australia. While the focus is on coastal adaptation planning in Victoria, the insights generated are intended to contribute to broadening the way in which adaptation is conceptualized.     

Conflict Resolution through Negotiation in a Railway Open Access Market: a Multi-agent System Approach

Abstract

Open access reforms to railway regulations allow multiple train operators to provide rail services on a common infrastructure. As railway operations are now independently managed by different stakeholders, conflicts in operations may arise, and there have been attempts to derive an effective access charge regime so that these conflicts may be resolved. One approach is by direct negotiation between the infrastructure manager and the train service providers. Despite the substantial literature on the topic, few consider the benefits of employing computer simulation as an evaluation tool for railway operational activities such as access pricing. This article proposes a multi-agent system (MAS) framework for the railway open market and demonstrates its feasibility by modelling the negotiation between an infrastructure provider and a train service operator. Empirical results show that the model is capable of resolving operational conflicts according to market demand.     

Evaluation of the Transferability of Incident Detection Algorithms Developed for Singapore Expressways

ABSTRACT

Two new detection algorithms, single-station DV (dual-variable) and dual-station CODE (COmbined Detector Evaluation) were developed earlier using 160 incidents collected along Singapore's Central Expressway (CTE). The transferability of these CTE-developed algorithms is assessed, as a case study, using 100 incidents collected from the Tullamarine Freeway and South Eastern Freeway in Melbourne, Australia. The investigation covers the differences in traffic detector systems (loop detectors versus video-based), road geometry and behaviour between drivers in Singapore and Australia. The re-calibrated application of these algorithms to freeways in Melbourne yielded a reasonably good detection performance as well as satisfying the average expected performances of seven traffic management centres surveyed in the USA. The results suggested that the detection logic of the algorithms developed for CTE possessed reasonably good transferability and are also suitable for receiving traffic inputs from video-based detectors as well as from loop detectors.     

Complex Network Topology of Transportation Systems

ABSTRACT

As a strategic factor for a country to survive in the global competition, transportation systems have attracted extensive attention from different disciplines for a long time. Since the introduction of complex network theory in the last decade, however, studies on transport systems have witnessed dramatic progress. Most roads, streets, and rails are organized as a network pattern, while link flows, travel time, or geographical distance are regarded as weights. In this article, the authors will present the current state of topological research on transportation systems under a complex network framework, as well as the efforts and challenges that have been made in the last decade. First, different kinds of transportation systems should be generalized as networks in different ways, which will be explained in the first part of this paper. We follow this by summarizing network measures that describe topological characteristics of transportation networks. Then we discuss the empirical observations from the last decade on real transportation systems at a variety of spatial scales. This paper concludes with some important challenges and open research frontiers in this field.     

Flexible strategic planning of transport systems

Abstract

This paper presents a decision support methodology for long-range planning of transport systems that exhibits strategic flexibility and stochastic system parameters. Unlike one-off strategic decisions, flexible decisions should be dynamically reformulated with time. The proposed methodology is based on the construction of a tree structure of multiple interlinked tactical planning problems, each associated with a scenario in the tree, where problems under scenarios at intermediate dates incorporate in their formulation the solution of the corresponding problems associated with past (future) connected scenarios. The resulting tree structure of interconnected planning decisions becomes a strategic-tactical decision support system that allows managers to formulate suitable flexible strategic decisions that mitigate the consequences associated with downside scenarios while taking advantage of the upside opportunities. The methodology is applied to the planning of a fleet deployment through charter contracts where contract prices depend on both market behavior and the duration of the contract itself.     

不确定时滞系统的PD型迭代学习控制算法

针对不确定时滞系统,在网络时滞范围已知情况下,采用改进PD型迭代学习控制算法补偿网络时滞.在初态是严格重复时,给出这类系统的极限轨迹和迭代输出收敛于该极限轨迹的充分条件.并与P型迭代学习控制算法进行比较.仿真结果表明改进后的PD型迭代学习控制算法能够有效地补偿此类时滞.当网络时滞范围变窄时,能够更加精确跟踪极限轨迹.在相同迭代次数情况下,PD型迭代学习控制算法比P型迭代学习控制算法能更快收敛于极限轨迹.     

火电厂过热汽温串级PID的快速稳定优化

针对火电机组大迟延的特点,提出了一种基于鲁棒约束的串级PID（比例－积分－微分）控制器稳定域优化方法．该方法首先根据时延系统的模型得到串级PID控制器参数的稳定域,然后利用鲁棒灵敏度函数的最大值获得最优的控制器参数．通过对火电机组过热汽温串级控制系统的仿真研究,表明该方法可以快速地确定串级控制器的最优参数,为火电机组热力系统的PID控制器参数优化提供了一种简单有效的方法．     

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随着城市汽车保有量的不断增加,交通拥堵日益频繁;匝道控制是通过调节入口匝道车辆数,来缓解快速路匝道交汇处拥堵的有效方法.本文同时考虑快速路和入口匝道上的实时密度设计了匝道控制优化算法,该算法旨在控制快速路密度接近其最优值,同时减少匝道上的排队数;通过PARAMICS仿真软件对算法进行验证,并与ALINEA、Demand Capacity算法进行了比较,仿真模拟统计了快速路交通流密度、匝道排队数、总车辆行程时间以及下游流量数据.分析结果显示,实时密度控制算法是有效的,能够维持干线最大流量,保持路网交通条件的动态平衡,并且尽可能地减少排队长度.     

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城市是一个高度复杂的大系统,城市布局、城市设计是城市交通出行特性的决定因素,而交通系统网络格局构成城市的机理,并决定城市经济的可达性,影响到城市经济与人民生活的所有层面.过去的十年中,能源基金会可持续城市项目与国家相关部委及城市合作,在可持续城市和交通系统规划、建设中做了大量工作.本次论坛主题为“系统科学与可持续城市交通理论与实践”,从可持续城市项目以及昆明可持续城市规划设计、济南快速交通规划与实践、重庆山城步道规划与应用等方面,共同探讨土地使用与城市交通协调发展的可持续城市交通之路.     

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长期以来,作为城市规划研究热点,城市土地利用和交通之间相互影响的研究相对脱节.近年来,该状况逐渐得到改观,研究人员开始将交通规划与城市用地布局方式相联系.本研究主要模拟给定城市区域土地利用的时空变化过程,帮助正确认识及处理城市交通发展与土地利用的相互关系.研究针对美国佛罗里达州Orange County 1990年与2000年土地利用类型的变化,利用元胞自动机(CA)在微观土地利用,空间格局等方面的优势,采用地理信息系统动态模型来实现海量数据的获取、储存以及更新.同时,借助MatLAB软件的数学计算能力,开发出基于逻辑回归的元胞自动机土地预测模型.基于实际土地利用的模拟结果表明,该模型充分利用元胞自动机的特点及优势,合理考虑土地利用系统中时空变量的复杂性,结果可靠,为正确理解土地利用变化提供了很好的帮助.