未知环境中水下无人航行器的路径规划方法

针对水下无人航行器路径规划需要提前获得海图以得到全局障碍物信息,难以做到未知环境下实时规划路径的问题,提出一种对探测空间进行采样并判断采样点是否具有障碍,最终将探测到的障碍结果加权赋值给A*算法待扩展点的方法,实现了探测与路径规划同步进行,同时考虑到航行器的运动学约束,将A*算法的搜索域修正为圆域并且仅搜索在运动学约束...     

日本筑波快线快慢车行车组织特点及启示

日本筑波快线作为东京都市圈市郊铁路新建通车最晚、运用新技术最多的线路,其规划设计和运营管理方式值得国内借鉴。本文从行车组织角度,首先在分析日本筑波快线规划背景和运营情况的基础上,研究其不同车站、不同圈层、不同性质、不同时段、不同方向客流分布特征及其对应的行车组织策略;然后为探究快慢车行车组织模式下的工程方案和工程规模,分析筑波快线全线配线的设置特点和不同型式配线对应的运营功能,并探讨筑波快线乘客界面处理的相关举措。最后,结合国内轨道交通的发展需求,从快慢车开行原则,快车服务对象、开行时段、开行种类和对数,避让站布置原则,复杂行车组织方案的运行图编制等方面提出促进我国市域(郊)铁路发展的经验启示。     

上海市市域轨道交通线的规划设计理念及其应用

R线是一种贯穿整个市域,直接沟通集中城市化地区与郊区之间联系的一种轨道交通模式,以上海市城市轨道交通网络规划设计为例,论述市域R线的作用、功能及其应用等。并通过对R线模式的比较结合上海城镇体系规划和具体特点,建议上海R线采用贯穿整个市域并通过上海市市中心区的方案。     

城市轨道交通的建设理念及其实现

从工程实践出发,结合城市轨道交通的建设标准和规范,通过规划选址、资源整合共享、设计体现等三个视角, 总结归纳出了城市轨道交通在规划、设计、建设中普遍遵循的一些理念,并对这些理念的实现做了初步探讨,从规划、细节设计等方面提出落实相应理念的建议。     

荆门市综合交通运输系统总体布局规划

文章运用区域综合交通规划学、系统工程学、区域经济学和旅游经济学等多学科研究方法,针对我国“十二五”期间大力发展旅游业和优先建设交通基础设施的特殊背景,以荆门市交通运输系统为研究对象,综合考虑城市交通、过境交通、旅游交通及其各种交通方式的综合协调,对荆门市的综合交通运输网络进行总体布局规划。     

海外港口绿地项目规划方法与原则

随着"一带一路"倡议的不断推进,中国的设计单位越来越多地参与到海外港口绿地项目的规划工作中。由于国内目前还没有成熟的指导性文件对规划的方法和原则进行说明,本文结合吉布提与印尼港口项目实例,介绍海外绿地项目规划应包含的内容和应遵循的工作流程,并总结出规划的原则,包括顺应自然地形、保护自然环境;土方挖填平衡;弹性发展,注重起步工程实施性;按需集约化布置、区块划分明晰;综合考虑经济效益的基础上保证项目每一期的自生性。这些工作实践的总结可为未来海外港口绿地规划工作提供借鉴。     

Identifying the most critical transportation intersections using social network analysis

Traffic congestion negatively impacts our society. Most of the traditional transportation planning techniques – though effective – require rigorous amounts of data and analysis which consumes time and resources. This paper uses social network analysis (SNA) to analyze transportation networks, and consequently corroborate the effectiveness of SNA as a complementary tool for improved transportation planning. After creating the connection between the language and concepts of SNA and those of transportation systems – as well as developing a model that utilizes different SNA centrality measures within the transportation context – the authors utilize SNA to investigate traffic networks in three case studies in the state of Louisiana, analyze the results and draw conclusions. To this effect, with minimal cost and time, the model identifies the most critical intersections that should be further investigated using traditional techniques. These results are in agreement with the findings of Louisiana’s Department of Transportation and Development.     

The changing role of decision support instruments in integrated infrastructure planning: lessons from the Sustainability Check

This article draws lessons about recent innovations in decision support for coping with challenges in integrated infrastructure planning strategies. After setting up a conceptual framework for the scope of analysis and the use of information in infrastructure planning, the empirical section explores the introduction of early-stage sustainability assessment tools. Data collection draws on experiences gained in the Netherlands with a new tool: ‘Sustainability Check’. We conclude that such instruments have a number of capacities that address the challenges of area-oriented planning: (a) bringing together information about the comprehensive value of alternatives, (b) facilitating the generation of alternatives, (c) addressing institutional fragmentation by learning about referential frames, and (d) adding contextual perspectives to the ‘hard’ outcomes of conventional tools. We also conclude that tools such as Sustainability Check should not be seen as a replacement for conventional decision support tools, but rather as complementary to them.     

Weekly container delivery patterns in liner shipping planning models

This paper addresses a fundamental question related to nearly all container liner shipping planning models: whether the implicit assumption of identical container delivery pattern every week is valid in a situation of identical shipping services and identical cargo demand every week. We prove that when the number of containers transported from one port to the next is formulated as a continuous variable, the resulting mathematical model with an identical container delivery pattern is equivalent to the model with general container delivery patterns which can be different in different weeks. When the number of containers transported is formulated as an integer variable, the model with an identical container delivery pattern is not equivalent to the model with general container delivery patterns. However, the difference between the optimal objective values of the two models is negligible for practical applications. In sum, little, if not nothing, is lost by assuming an identical container delivery pattern in liner shipping planning models.     

Optimal reefer slot conversion for container freight transportation

Given a fleet of container ships of varying capacity, a cost-efficient approach for improving fleet utilization and reducing the number of delayed containers is to optimize the sequence of container ships in a given string, a problem which belongs to the large ship-deployment class. A string sequence with ‘uniformly’ distributed ship capacity is more likely to accommodate a random container shipment demand. The number of one’s total ship slots acts as a gauge of the capacity of the container ships. Meanwhile, there are two types of ship slots: dry slots and reefer slots. A dry slot only accommodates a dry container, while a reefer slot can accommodate either a dry or a reefer container. The numbers of dry and reefer slots for ships in a string are different. Therefore, in this study, we propose a model that considers both dry and reefer slots and use it to elucidate the optimal ship-deployment sequence. The objective is to minimize the delay of dry and reefer containers when the demand is uncertain. Furthermore, based on the optimal sequence deduced, the study also investigates the need to convert some dry slots to reefer slots for the container ships.