Using the sustainability footprint model to assess development impacts of transportation systems

A review of the sustainability literature reveals the lack of viable frameworks and management tools that can be used to accommodate both spatial and temporal variability in how stakeholder entities meet their sustainable development goals, taking into account the fact that different entities may need to pursue different priorities and also deal with different constraints and schedules at different stages of their development. This paper presents a sustainability footprint framework and model that may be used in analyzing the impacts of transportation and other infrastructure systems on regional sustainable development. A specific application of the framework is in the quality of life contributions that transportation systems may make to communities as a function of their impacts on natural assets that contribute inputs and absorb the byproducts of development. The application is illustrated in a case study that uses data from the Atlanta and Chicago Metropolitan Areas to demonstrate how this model may be applied in real life situations. The implications of this model for transport systems research, policy and practice are discussed. The value of this framework and model lie in introducing both spatial and temporal flexibility that may enable stakeholders with widely different priorities to reach consensus on interim goals for sustainable development to ultimately attain sustainability.     

Capitalization of BRT network expansions effects into prices of non-expansion areas

A before and after hedonic model is used to determine the property value impacts on properties already served by the transit system caused by extensions to Bogotá’s bus rapid transit system. Asking prices of residential properties belonging to an intervention area (N = 1407 before, 1570 after) or a control area (N = 267 before, 732 after) and offered for sale between 2001 and 2006 are used to determine capitalization of the enhanced regional access provided by the extension. Properties offered during the year the extension was inaugurated and in subsequent years have asking prices that are between 13% and 14% higher than prices for properties in the control area, after adjusting for structural, neighborhood and regional accessibility characteristics of each property. Furthermore, the appreciation is similar for properties within 500 m and properties between 500 m and 1 km of the BRT.     

An ensemble approach for conflict detection in Free Flight by data mining

Airborne separation assurance is a key requirement for Free Flight operations. A variety of conflict detection (CD) and resolution algorithms have been developed for this task. A lack of rigorous evaluation and the existence of an infinite number of possible conflict geometries in Free Flight makes the choice of which algorithm to be placed in the cockpit a challenging task for the designers of future air traffic management (ATM) systems. In this paper, we propose an ensemble approach for CD in Free Flight. The ensemble consists of several CD algorithms, a rule set for each algorithm describing its learned behavior from its past performance and a switch mechanism to choose an appropriate CD algorithm given probe characteristics. A novel mechanism to evolve complex conflict scenarios, using genetic algorithms (GA), is developed and integrated in a fast time air traffic simulator to generate the performance data of CD algorithms. Data mining techniques are then employed to identify implicit patterns in the probe characteristics where the CD algorithms missed or falsely identified a conflict. These patterns are formulated as rule sets for each CD algorithm and are then used by a switch in the ensemble to route a probe for conflict prediction. Given probe characteristics, the CD algorithm, which is less likely to miss or falsely identify a conflict, is selected to evaluate the probe for potential conflict. The performance of the ensemble and of individual algorithms is evaluated by comparing the Pareto efficient set of solutions generated by them. The ensemble approach demonstrates a significant reduction in the number of missed detects and false alarms as compared to individual algorithms. The proposed methodology is capable of accommodating existing as well as new CD models and can be extended to other ATM concepts as well.     

Tradeoffs in incremental changes towards pedestrian-friendly environments: Physical activity and pollution exposure

A microsimulation of individuals’ activities is used in the context of a risk analysis framework to assess the impacts of hypothesized changes to the built environment on personal energy expenditure and on inhalation of air pollutants. Uncertainty is assessed using Monte Carlo simulations and sensitivity analyzes. We find both simulated individuals that augment and others that reduce their energy expenditure and inhalation dose of pollutants, with median increases displaying larger magnitudes than the decreases. Up to 75% of the population has significant increases in energy expenditure and pollutant inhalation. We also find, however, high uncertainty associated with the estimates. Results differ considerably depending on the travel mode choice model used in the simulation.     

用超声波检测评定焊缝的不连续性

用超声波检测,根据测试的灵敏度,可获得焊缝不连续性的6个基本方面:(1)与标准反射物的回波信号相比较,从试样的反射波幅的大小可以近似地估计反射区的大小.     

Ship ballast water as a main vector of marine introductions in the Mediterranean Sea

Marine invasive species are currently recognized as one of the most significant threats to global biodiversity. Marine bioinvasions are more likely in the Mediterranean Sea because of its wide temperature range, degraded habitats, historical and high volume of shipping traffic, and high occurrence of aquaculture. One of the main vectors of marine introductions globally and Mediterranean-wide is commercial shipping. Of the 3,000–4,000 species transferred around the world via commercial vessels, approximately 30% of these species may have been redistributed in the Mediterranean. Ships and marine invasive species arriving in the Mediterranean are mainly from temperate to cold-water regions. Standardized research and management approaches between countries are required to address the threat of ballast water borne marine invasives on a global scale. Regionally, a Mediterranean program involving the different states is currently needed to develop a common line of research and management operations.     

The economic impact study of maritime policy issues: application to the German case

Input-output analysis basically provides an estimation of a sector's economic impact by taking into account the indirect effects on all other sectors. For purposes of policy making, however, this may produce rather rigid and inaccurate results. This paper, therefore, introduces some extensions to the basic impact analysis. These extensions secure flexibility, completeness and accurateness of the outcomes. First, an accurate cost structure is determined in a bottom-up approach, i.e. by using data from a sample of representative companies. This allows for reliable outcomes and a flexible definition of sub-sectors. Secondly, the analysis is made in an intercountry context. Thirdly, the expenditure effects of generated income are determined by a macroeconomic module. Fourthly, company-level responses to alternative policy scenarios are investigated and translated into changing model parameters. These four basic elements are applied in a case study concerning the shipping sector of Germany. The scenarios are a continuation of the present policy, a laissez-faire policy, and two framework policies in which the government creates a favourable environment for shipping companies. For each scenario, the effects on value added, employment, tax revenues and expenditures are analysed and evaluated. This paper, thus, shows the relevance of accordingly amplified input-output analysis for policy purposes.     

Fleet deployment optimization for liner shipping Part 2. Implementation and results

We use linear programming (LP) for solving the problem of the optimal deployment of an existing fleet of multipurpose or fully containerized ships, among a given set of routes, including information for lay-up time, if any, and type and number of extra ships to charter, based on a detailed and realistic model for the calculation of the operating costs of all the ship types in every route and on a suitable LP formulation developed in earlier work of the authors. The optimization model is also applicable to the problem of finding the best fleet compostion and deployment, in a given set of trade routes, which may be the case when a shipping company is considering new or modified services, or a renewal of the existing fleet. In addition, two promising mixed linear-integer programming formulations are suggested.     

全球集装箱航运业发展趋势权威性预测

集装箱航运业遭遇种种难题可以理解船东和集装箱航运公司担心舱位运力的增长的速度将远远超出人们最乐观的需求预测。但是为何许多托运人也在担心这种情况呢?     

初应力状态下夹芯复合材料曲梁面板的局部振动的理论分析

在船舶领域,以复合材料层合面板及泡沫芯材组成的夹芯复合材料板梁结构已大量应用在游艇及复合材料高速艇上.文章研究了受初始静载荷作用下夹芯复合材料曲梁的面板的局部自由振动问题,并给出一种相应的理论分析方法.文中通过将芯材简化为Winkler弹性地基,将面板简化为一复合材料曲梁,从而使所研究问题蜕化为有初始静载荷作用下弹性地基上任意曲梁的固有振动问题.在局部振动位移是基于初始静载平衡位置并与初始位移相比是小量的假定的基础上,根据能量原理推导出面板的运动方程.研究的结果表明,该面板的局部振动不只取决于面板的弯曲刚度和长度,以及芯材的弹性刚度,也在很大程度上取决于梁的曲率及面板所受到的初始轴向压力.