Designing a decision support model for the LNG market

Abstract

As the Liquefied Natural Gas (LNG) market is supply-driven and subject to long-term contracts, both liquefaction companies and shipowners need to make strategic decisions on fleet chartering requirements. These planning decisions become ever more difficult in light of the transformations permeating the LNG market, propelling into a more competitive market with more flexible trades and expanding spot markets. The overcapacity of LNG ships during 2008–2009 triggered by massive overcontracting is a good case in point where the use of decision support models would have been beneficial, especially considering the fortunes and risks at stake. In this paper we present an LNG shipping model that effectively supports decision-making in practice. To demonstrate the value added of the model, we study the implications of LNG project delays and increased decommissioning of ships with respect to market balance and fleet requirements.     

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.     

Daily newspaper distribution planning with integer programming: an application in Turkey

Abstract

This paper concerns the newspaper distribution problem. It addresses the transportation of newspapers from printing plant to newsagents with distribution vehicles under various particular constraints. The objective is to minimize the distance traveled by the vehicles and/or the number of vehicles. In this study, the routes for vehicles of a leading newspaper distributor company in the Turkish press sector are examined. The problem is defined as determining optimal delivery routes for a fleet of homogeneous vehicles, starting and ending at the printing plant that is required to serve a number of geographically dispersed newsagents with known demands under capacity and time constraints, while minimizing the total distribution cost. An integar linear programming model is proposed as a solution using Cplex. Computational results demonstrate that the proposed model is fast and able to find optimal solutions for problem scenarios with up to 55 newsagents within reasonable computing times. It was found that the proposed model reduced the delivery cost by 21% on average when compared to the current manual method. The results show that this model is adequate for medium-sized distribution problems.     

Bridging the gap between complex data and decision-makers: an example of an innovative interactive tool

Abstract

The increasing capacity of technological tools, as well as the advent of geographic information systems, has multiplied the ability to process large sets of microdata. At the same time, modeling concerns and the quest for a more in-depth understanding of individual behaviors is requiring more, and better, data. The gap between scientific modeling and informational tools for decision-making seems to be widening.

In the Greater Montreal area, large sets of microdata have been available for more than 30 years. Along with the development of modeling and planning tools, particular attention has been given to the continuous enlightening of planners and decision-makers with respect to the outcomes of the various surveys. This has led to the development of particular interactive tools, specifically addressed at local planners, which present the most significant information regarding travel and demography, for geopolitically relevant areas.

This paper presents the most recent interactive tool that has been developed for local planners in the Montreal area. It integrates information from both the most recent travel survey held in the region and the Canadian census. It offers both ease of use and relevant analytical means to assist in exploring the complex relations between spatial locations, demographic features, and activity-travel indicators.     

基于Maklink 图和遗传算法的改航 路径规划方法研究

为了保障恶劣天气下的飞行安全,航班需要采取改航策略避开危险区.采用已 有的以改航路径最短为目标,以航段最小距离、避开危险区、转弯角度等为约束条件的规 划模型,设计了3 阶段方法研究改航路径规划.首先应用Maklink 图和Dijkstra 算法规划一 条能够避开危险区的路径,接着应用遗传算法优化路径,最后进行路径调整以满足约束 条件.算例仿真结果显示,应用本文方法得到的改航路径长度较短,转弯次数少、转弯角度 小,计算效率高.仿真结果说明,应用本文提出的方法获得的改航路径满足目标和约束要 求,验证了该方法的可行性和有效性.     

铁路客运站始发列车检票时间算法研究

铁路客运站始发列车检票时间通常采用写实查定的方法来确定,工作量大且 不能及时反映客流不均衡性和检票设备更新后的变化,因此有必要对始发列车检票时间 进行定量化研究.本文首先采用K-S 检验方法,对旅客检票时间随机分布进行建模研究; 其次,针对旅客检票过程中的排队、拥挤和换队行为,构建基于实时人群密度的路径规划 算法,建立始发列车旅客检票过程仿真模型,并对模型的正确性进行验证;最后,以发送 旅客人数和自动检票闸机数量为自变量设计正交试验,根据仿真实验数据分析结果,提 出铁路客运站始发列车检票时间算法,并对算法的正确性进行验证.     

Visual Basic在地基系数数据处理软件中的应用

介绍地基系数数据处理软件的设计思路及各部分功能的实现方法.该软件实现了试验数据的传输、试验数据和试验信息的保存与打开、试验结果的计算、曲线的绘制、文档输出等功能.该软件已取得计算机软件著作权并在路基现场检测中应用.     

基于道路功能分类的县域现代农业园区公路网规划的探索与实践

以农业园区公路为研究对象,结合实际案例,对县域现代农业园区公路功能定位和规划方法进行探索与实践,形成具有实用性、可操作性的方案,可为类似公路网规划建设提供参考。     

城市地下快速路进出口布置与交通功能关系研究

通过阐述城市地下快速路系统的定位及其交通功能,以及城市地下快速路进出口布置与其交通功能的关系,分析出地下快速路起终点进出口、中间进出口及地下空间联系进出口布置与地下快速路系统交通功能的关系及对地面路网的影响。结合地下工程的特点初步探讨城市地下快速路进出口布置原则。     

论区域公路网布局理念与方法的变革

分析以往的公路网规划理论与方法在规划思想、规划目标、规划体制上存在的缺陷和弊端,结合现阶段公路网规划面临的新问题、新要求,提出公路网规划任务上的变化和规划理念上的变革。最后以区域城镇空间结构为依托,以交通数据预测为补充,提出"城镇空间优化-路网发展目标-网络布局-线路规划"多层次渐进的综合规划方法。