城际铁路列车停站方案的遗传算法求解

我国城市群快速发展,城市间人员交流密切频繁,城际铁路成为城际间旅客的重要出行方式。合理的城际铁路列车停站方案可以提高城际铁路的竞争力,提升城际铁路的分担率。分析停站方案相关的运营收益和旅客出行成本,以铁路运营收益最大和旅客出行成本最小为目标函数,以车站服务频率、设备能力、列车停站次数等作为约束条件,建立城际铁路列车停站方案的多目标混合0-1规划模型,运用理想点法和遗传算法求解。算例结果表明,该模型和算法可以优化得到铁路运营收益和旅客出行成本均较优的停站方案。     

Analysing the impact of restructuring transportation,production and distribution on costs and environment – a case from the Thai Rubber industry

Transportation and distribution are key elements to successful supply chains, however there is some disagreement regarding the impact of distribution and transportation restructuring on costs and the environment. This paper explores the use of an optimisation model of Thailand’s rubber industry supply chain, to assess the impact of distribution and transportation on costs and greenhouse gas emissions. It has previously been observed that there is a positive correlation between transportation cost reduction and environmental impact, nevertheless the correlation is not clearly established when the distribution system is restructured. This paper is divided into two parts: the first part examines the impact of transportation service capacity on distribution decisions; the second part of the paper aims to examine the impact of restructuring the distribution network considering multi-modal options on cost and greenhouse gas emissions. For both parts a scenario analysis is utilised in conjunction with an optimisation model to derive the best possible answer in terms of costs and GHG emissions. In this paper, the results obtained indicate that the impact on cost minimisation from the increase in rail freight service capacity is marginal, while the impact on GHG emission minimisation is more significant. In terms of short-sea shipping prices and service capacity, the scenario analysis shows a slight positive impact on cost minimisation but no positive or negative impact on GHG emission minimisation. Results also confirm that in terms of economic advantages, distribution network restructuring provides greater benefit to the industry than does capacity development for the transportation service.     

Moving beyond the iceberg model: The role of trade relations in endogenizing transportation costs in computable general equilibrium models

Modeling trade and transportation costs is an essential part of multiregional or spatial computable general equilibrium models where interregional trade plays an important rolein shaping economic activity. The majority of such models use the iceberg trade cost approach where part of the produced output (representing the material costs of transportation) is assumed to melt away during transportation. There are a few models which employ a more refined approach with an explicit transportation sector providing transportation services which are then used to ship goods between locations. In this paper we show that this approach, although much more convenient than the iceberg approach, still lacks full usability due to the fact that markets, hence prices are defined at the regional level and as a result, transportation costs can not be endogenous at the trade relation level. Moreover, under regional level market clearing the iceberg and the more detailed approach are equivalent. We propose to refine the definition of market equilibrium and move it to the trade relation level. Using this approach we can gain full advantage of the explicit transport sector in the model with respect to trade cost evolution. We show through simulations that refining the way trade costs are modelled indeed gains new insights, and that moving the market definition to the trade relational level leads to qualitative changes in the effect of labor supply shocks on main model variables. The paper also presents a method to estimate a SAM by reallocating data from standard industries to a transportation sector which is then consistent with the model setup. This SAM can be used to calibrate the refined model with a detailed transportation sector.     

我国航空运输业市场结构演变分析

在阐述市场结构分析的主要理论和方法的基础上,测算了我国主要航空公司近年来市场份额的比重和变化,分析了市场结构变化特点。根据产业经济学中市场结构的相关理论,利用行业集中度和赫芬达尔-赫希曼指数两个指标,结合我国航空运输业的实践,计算了我国航空运输业市场2001—2009年的绝对集中度、HHI指数和倒数N指数,一致得出我国航空运输业是一个寡头垄断型产业,其垄断强弱程度呈"增强—减弱—增强"动态变化。     

Telecommunications/ transportation substitution and energy conservation Part 2

Part 1 of this article reviewed existing research both on attitudes toward telecommunications substitution for travel and on operational experiments with teleconferencing and telecommuting. Part 2 examines major factors influencing substitution, including government policy. It concludes that government policy can significantly facilitate telecommunications substitution for travel and, indeed, the achievement of any real measure of substitution may depend upon proactive government policy. However, this is an unlikely prospect in the current US national policy environment.     

The environmental effect of car-free housing: A case in Vienna

A case-control study of the car-free model housing project in Vienna was conducted to evaluate whether people living in this settlement have more ‘sustainable lifestyles’ than people living in comparable buildings in Vienna. Another aim was to identify the lifestyle characteristics and household activities which significantly influence the environmental impact of the residents of the car-free housing project and a control group. The control group, referred to as the reference settlement, was chosen from a nearby building complex, with similar characteristics, but without the car-free feature. Household consumption patterns were estimated based on interviews in combination with data from the Austrian consumer expenditure survey and the national accounts. The evaluation of household environmental impacts uses emissions estimates from the Austrian national accounting matrices including environmental accounts and data from life-cycle assessments. Households from the car-free settlement have substantially lower environmental impacts in the categories of ground transportation and energy use; their CO₂ emissions of these two categories are less than 50% of those living in the reference settlement. The households in the car-free settlement have somewhat higher emissions in the categories air transport, nutrition, and ‘other’ consumption, reflecting the higher income per-capita. As a result, the CO₂ emissions are only slightly lower than in the reference settlement, but the emissions intensity is 20% lower. Both household groups have significantly lower environmental impacts than the Austrian average reflecting less car use and cleaner heating energy in Vienna.     

Min–Max exact and heuristic policies for a two-echelon supply chain with inventory and transportation procurement decisions

We study the problem in which one supplier delivers a product to a set of retailers over time by using an outsourced fleet of vehicles. Since the probability distribution of the demand is not known, we provide a Min–Max approach to find robust policies. We show that the optimal Min-Expected Value policy can be very poor in the worst case. We provide a Min–Max Dynamic Programming formulation that allows us to exactly solve the problem in small instances. Finally, we implement a Min–Max Matheuristic to solve benchmark instances and show that it is very effective.     

Design of a rail transit line for profit maximization in a linear transportation corridor

This paper addresses the design problem of a rail transit line located in a linear urban transportation corridor. The service variables designed are a combination of rail line length, number and locations of stations, headway and fare. Two profit maximization models, which account for the effects of different transit pricing structures (flat and distance-based fare regimes), are proposed. In the proposed models, the effects of passenger demand elasticity and population density along the urban corridor are explicitly considered. The solution properties of the proposed models are explored and compared analytically, and the indifference condition for the two fare regimes in terms of the operator’s net profit is identified. A heuristic solution algorithm to solve the proposed models is presented. Numerical examples are provided to show the effects of the fare regimes, rail capital cost and urban configuration (in terms of urban population distribution and corridor length) on the design of the rail transit line and the profitability of the rail transit operations.     

塔山煤矿地面输料钻孔设计与应用研究

同煤集团塔山煤矿针对二盘区工作面距离井口较远,材料运输难度大的问题,提出在二盘区对应地面工业广场向井下打钻孔,建立混凝土集运站,通过钻孔向井下运输混凝土物料的方案,钻孔参数:钻孔垂深为500m,0~80m范围开孔φ750mm,安装φ550mm护壁管;80~500m开孔φ500mm,安装φ325×30mm耐磨铸钢管,解决了混凝土运输的问题,具有较大的社会效益和经济效益。     

海运运价指数研究综述

海运运价指数反映航运市场水平的动态变化,对贸易成本有重要影响。结合近些年海运运价指数的文献研究进展,首次对波罗的海干散货运价指数(BDI)、波罗的海原油运价指数(BDTI)以及中国出口集装箱运价指数(CCFI)三个海运运价指数的影响因素、波动周期性和指数预测方法研究领域的成果进行归纳整理和对比分析,为航运公司、船舶中间商的经营决策提供参考。影响因素主要从供需关系下的运输成本、航运市场、经济环境三个因素展开,波动周期结合各航运市场的特征并分析原因,预测方法则围绕线性模型与非线性模型进行比较,在文献述评的基础上指出目前研究的不足与未来的研究方向。