基于国际视角下国内公铁联运发展探析

文章分别分析了美国、加拿大、德国、法国及日本公铁联运的发展经验,总结公铁联运链条高效化的本质在于实现四个方面的连结性,并结合上述分析,从服务提供商、基础设施建设、信息平台建设、政策支持四个视角与我国公铁联运情况对比,以寻求我国公铁联运的发展阻滞所在。最后针对性地提出一些建议。     

基于混合指数选择模型的机场航线开辟研究

针对国内中小机场布局日益完善,而新航线开辟选择方面缺少量化的问题,从机场的角度出发,结合旅客潜在需求量指标、连通性指标以及空铁竞争指标构建混合指数选择模型,来研究中小机场新航线的开辟选择问题,为机场航线开辟选择提供量化参考依据.通过对日照机场作为研究对象进行实例验证,在预计3年旅客吞吐量达到120万、机场设计年起飞架次为79500次、航线补贴金额为100万的规划要求下,计划开通6条航线,运用混合指数选择模型进行航线开辟选择,求出最优的6条航线,达成规划要求.实例证明模型在航线开辟方面具有可行性,可为机场的航线开辟选择提供参考.     

Living in a bubble: potential gains from flexible water management policies

We study Swedish implementation of the European Union’s Water Framework Directive, and compare the current implementation strategy with more flexible ‘bubble’ schemes, where measures can be traded among various locations within the same river system to reach the overall environmental target. Two different Swedish river systems, the Mörrum system with small-scale hydropower plants, and the Ångerman system with larger plants, are studied. We find that the environmental benefits that current policies are likely to accomplish could be achieved at well under half the cost in the Mörrum system, and at less than a tenth of the cost in the Ångerman system.     

3—连通、3—正则图中的圈

本文介绍了3—连通、3—正则图中包含给定点集的大子集的圈。     

基于空间效能的城市生态网络构建*——以亳州市为例

［目的］随着我国城镇化进程的不断加快，城市生态要素不断受到侵蚀，构建城市生态网络对城市生态系统保护和修复具有重要意义。［方法］文章基于空间效能的视角，以亳州市为研究对象，运用生态网络连接性、渗透性以及均衡性评价，从生态保护和生态修复两个层面构建城市生态网络。［结果］对“网络本体—影响区—辐射区”不同空间层次的效能进行分析，研究结果表明：在“网络本体”的连接性评价中，生态连接应将河流水系等进行贯通连接，形成城市的生态骨架，并整合破碎的生态斑点，形成规模较大的斑块。“本体—影响区”的渗透性分析表明亳州大部分绿地斑块形状呈现出规则且较为离散的状态。“本体—辐射区”的均衡性评价显示亳州河流水面及沟渠较多且均匀，但是连通性较差。［结论］因此，亳州市应构建包含4个重要生态保护点、3个主要生态修复点和三级廊道体系的生态网络，同时要维持其生态廊道的自然形态，处理好现状保护与建设的关系等方面内容。     

基于生态系统完整性与连通性的生态保护红线优化探讨——以长三角为例

研究目的:生态保护红线正处于评估与优化阶段,尝试基于生态系统完整性与连通性提出简便且易操作的优化指标与阈值。研究方法:InVEST,CASA和RUSLE模型,STARS(Sequential T-test Analysis of Regime Shift)突变检验。研究结果:(1)长三角地区破碎度持续增加导致水源涵养、土壤保持、生境质量和净初级生产力(NPP)4类生态系统服务呈显著下降趋势,存在4个以上的显著下降突变点,生态保护红线破碎度优化阈值为0.2;(2)长三角地区连通度指数持续增大显著提升4类生态系统系统服务,存在3个以上的上升趋势突变点,生态保护红线连通度优化阈值为90;(3)基于破碎度(0.2)和连通度(90)作为生态系统完整性与连通性优化阈值,长三角生态保护红线约17.25%的面积需优化,其中生态系统完整性不满足的占9.01%,生态系统连通性不满足的占0.02%,两者均不满足的占8.22%。研究结论:(1)建议将破碎度(0.2)和连通度(90)作为生态保护红线的完整性与连通性的优化指标与阈值;(2)未来应加强从生态系统结构、功能与过程完整性、生态系统稳定性与弹性等多维度筛选关键表征指标,利用更多的景观指数及不同的阈值设定方案,建立一套更加系统科学、可操作的生态保护红线优化指标体系。     

Effects of enhanced air connectivity on the Kenyan tourism industry and their likely welfare implications

This paper investigates the links between air connectivity, tourism benefits and welfare. It improves on the common practice in the literature by demonstrating avenues of tourism expansion and their welfare implications using both a partial and a general equilibrium model. The results of the gravity model show that there is a strong connection between air connectivity factors and incoming passengers. Simulation results of tourism expansion brought about by improved connectivity demonstrate that all household groups experience an improvement in their welfare but with lower impact on low-income agricultural households. The study concludes that formulating policies that address the air connectivity gap in Kenya would benefit the tourism sector and all households if co-ordinated with rural development initiatives.     

Spatial connectivity as a recovery process indicator: The L'Aquila earthquake

The main objective of this paper is to prove that spatial connectivity can be an effective spatial indicator for monitoring and evaluating the recovery process after the event of an earthquake. It integrates variables such as distance, travel time and quality of public transport service. We hypothesize that there is a relationship between the connectivity to the central business districts in cities, and the satisfaction with the locations of new settlements assigned to the homeless population during a recovery process. If this hypothesis holds true, then the satisfaction with new settlements will be correlated with the inhabitants' preference to either stay, or to search for a new site. This will then support the evaluation of the success of a recovery process. To prove this relationship we investigated the twelve months recovery process in L'Aquila in Italy. Spatial data sets were used and analyzed using GIS. Fieldwork data and interviews were conducted in order to investigate the satisfaction of persons living in newly established places outside of the city. We compared the strength of the desire of the interviewees to move away, against the travel distance and travel time to the city center. The statistical analysis reveals that the preference to search for another place was significantly correlated with the distance between new settlements and the city center of L'Aquila. To a lesser degree it was correlated with the travel time. The regression indicated that the distance between the new settlements and the inner city strongly influences the preference to either stay or to move.     

车载自组织网络路由协议研究进展与比较

车载自组织网络（VANET）是一种新型移动自组织网络。作为移动无线网络的热点研究领域,车载自组织网络的间歇连通性使路由设计充满挑战。首先阐述了车载自组织网络的主要特征和应用;在对车载网络路由协议进行分类的基础上,详细描述了一批有代表性的路由协议;对比和总结了各类路由协议的特点,并提出相关研究建议,可为车载网络路由协议研究提供一定的参考价值。     

A strategic model of port-hinterland freight distribution networks

This paper presents a strategic model for port-hinterland freight distribution networks. The approach utilizes a combination of a multi-objective optimization model to estimate locations and networks of distribution centers and an assignment model that recognizes distributed service level preferences. Our example application concerns the European continent and is transferable to other regions. The model calibration is able to explain the European port-hinterland distribution structures satisfactorily. We compute novel performance measures that take into account port-hinterland distribution structures. The measures include port-hinterland transport cost, port-hinterland transport time, and distribution center-hinterland transport time. These measures can provide inputs for port-connectivity studies.