公路工程材料定价技术及应用分析

公路工程材料价格对于项目的成本影响较为明显。通过分析公路工程材料的价值构成,提出了公路工程材料价格预测的步骤,可为工程材料价格的预测分析提供参考。     

Perceptions of the performance of state coastal zone management programs in the United States. II. Regional and state comparisons

A mail survey of coastal user groups, academics, and state coastal zone management program managers was conducted to determine the perceptions of the performance of state coastal zone management programs relative to the protection of coastal resources, the management of coastal development, the improvement of public access, and the management of coastal hazards. Information on the perceived importance of the selected issues to each of the 24 states being studied was also solicited. Findings on the perceptions of various categories of interest groups, academics, and program managers with respect to the overall performance of state coastal zone management programs in the four issue areas were presented in an earlier article, “Perceptions of the Performance of State Coastal Zone Management Programs in the United States”; (Knecht et al., 1996). The present article draws on a subset of these data—the responses from the coastal user groups and the academics—and presents the findings at the regional and individual state level. In terms of perceived performance of state coastal zone management programs on a regional basis relative to the selected issue areas, the highest rating went to the Great Lakes region for its management of public access. However, the North Atlantic region received the highest performance rating for the three other issue areas: protection of coastal resources, management of coastal development, and management of coastal hazards. Looking at state performance with regard to the coastal issues judged to be of most importance to the states—the protection of coastal resources and the management of coastal development—respondents indicated that states should improve their performance in both areas, with the greatest need related to the management of coastal development. Overall, the states of the North Atlantic, Great Lakes, and South Atlantic regions were perceived to be performing somewhat better relative to the four issue areas than the states in the Pacific and Gulf of Mexico regions. While the data do not shed light on the reasons for these regional differences, we suggest that, in the case of the Pacific region at least, the differences could be associated with higher expectations among the resident population with regard to environmental quality in general and coastal management in particular.     

Evaluating competitiveness using fuzzy analytic hierarchy process—A case study of Chinese airlines

With the development of a national market economy, the Chinese aviation industry is now confronted with international competition. Therefore, it is necessary to research the competitive status of Chinese national aviation, as well as advice on how to enhance the competitiveness of the Chinese aviation industry. The main objective of this paper is to propose FAHP as an effective solution for resolving the uncertainty and imprecision in the evaluation of airlines' competitiveness. In this paper, we review the research of industrial international aviation competitiveness at both home and abroad, discuss a theoretical framework for the study of aviation competitiveness, establish an index system with five first‐order indicators and 17 second‐order indicators, set up a Chinese aviation competitiveness model based on simple fuzzy numbers from the fuzzy analytic hierarchy process, and evaluate the competitiveness of five major Chinese airlines. The results showed that this model and these indicators are scientific and practical, with a wide range of application prospects for the purpose of improving and increasing Chinese airline competitiveness in the international market. The effective approach presented in this paper is especially applicable when subjective judgments on performance ratings and attribute weights are not accessible or reliable, or when suitable decision makers are not available. Copyright © 2011 John Wiley & Sons, Ltd.     

Adoption of Internet Services in Liner Shipping: An Empirical Study of Shippers in Taiwan

Abstract

The Internet service attributes desired by shippers were examined as well as a model that seeks to explain the intention of shippers to use Internet services in liner shipping. Using data collected from a survey of a group of shippers in Taiwan, the relationships among the constructs in the model were tested, namely: perceived usefulness, perceived ease of use, security and use intention. The results suggest that shippers perceive tracing to be the most important service attribute of Internet services, followed by checking for customs clearance, vessel schedules and electronic document services. The findings indicate that perceived ease of use is the major factor affecting the intention of shippers to use Internet services, and that perceived ease of use has a strong positive effect on perceived usefulness. The results also indicate that security has a positive effect on a shipper’s perception of ease of use. However, the influence of security on use intention and perceived usefulness was not supported in this study. The theoretical and practical implications of the findings on the intention of shippers to use Internet services in liner shipping are discussed.     

Traffic Performance Models for Dynamic Traffic Assignment: An Assessment of Existing Models

Abstract

This paper provides a review of the traffic performance models for dynamic traffic assignment (DTA) and it identifies the strength and weakness of existing models. Requirements for traffic performance models are identified and various forms of existing traffic performance models for DTA are reviewed and analysed according to the requirements. Non‐linear travel time models are shown to have some deficiencies that make them unsuitable for the analysis of time‐varying transportation networks. Even though linear‐type travel time models are identified as good candidates for the analysis of dynamic transportation networks, they have limitations from the practical point of view that travel time increases only linearly with the amount of traffic on the link. This poses a dilemma and it seems to be one whose resolution is an imminent precondition for DTA modelling to progress in a way that is both theoretically coherent and plausible in practical terms.     

TOPSIS在山区铁路线路方案比选中的二次改进

为克服传统TOPSIS(逼近理想解排序法)在山区铁路线路方案比选中不能排除指标间相关性干扰、易使决策工作复杂化的缺点,同时为能充分考虑决策工作的不确定性特征,首先,以马氏距离代替传统TOPSIS中的欧氏距离,实现第一次改进;接着,以相关系数矩阵代替马氏距离中的协方差矩阵,实现第二次改进;然后,运用语言类模糊数、区间数、...     

基于替代图的列车运行实时预测调度

对目前国内外列车运行优化调度的研究现状和方法进行了分析,进而结合替代图模型提出了一种基于预测控制机理的列车运行实时预测调度策略(RTPS).针对一个小型铁路网络,研究并验证了仿真平台对列车运行动态特性描述的功能.针对一个大型的荷兰铁路网络进行仿真.仿真结果表明,所提出的算法优于目前文献中的先到先服务(FCFS)、先离开先服务(FLFS)和避免最大当前代价(AMCC)的算法.本文所提出的调度算法可以为调度员提供更加优化的冲突决策方案.     

Macroscopic modeling of lane‐changing for two‐lane traffic flow

We propose a macroscopic model of lane‐changing that is consistent with car‐following behavior on a two‐lane highway. Using linear stability theory, we find that lane‐changing affects the stable region and the propagation speeds of the first‐order and second‐order waves. In analyzing a small disturbance, our model effectively reproduces certain non‐equilibrium traffic‐flow phenomena—small disturbance instability, stop‐and‐go waves, and local clusters that are affected by lane‐changing. The model also gives the flow‐density relationships in terms of the actual flow rate, the lane‐changing rate, and the difference between the potential flow rate (the flow rate that would have occurred without lane‐changing) and the actual flow rate. The relationships between the actual flow rate and traffic density and between the lane‐changing rate and traffic density follow a reverse‐lambda shape, which is largely consistent with observed traffic phenomena.     

Modeling transit technology selection in a linear transportation corridor

This paper proposes an analytical model for investigating transit technology selection problem from a perspective of transit authority. Given a transit technology alternative (e.g., metro, light rail transit, or bus rapid transit), the proposed model aims to maximize the social welfare of the transit system by determining the optimal combination of transit line length, number of stations, station location (or spacing), headway, and fare. In the proposed model, the effects of passenger demand elasticity and capacity constraint are explicitly considered. The properties of the model are examined analytically, and a heuristic solution procedure for determining the model solution is presented. By comparing the optimized social welfare for different transit technology alternatives, the optimal transit technology solution can be obtained together with critical population density. On the basis of a simple population growth rate formula, optimal investment timing of a new transit technology can be estimated. The proposed methodology is illustrated in several Chinese cities. Insightful findings are reported on the interrelation among transit technology selection, population density, transit investment cost, and transit line parameter design as well as the comparison between social welfare maximization and profit maximization regimes. Copyright © 2014 John Wiley & Sons, Ltd.     

An augmented Lagrangian origin‐based algorithm for link‐capacitated traffic assignment problem

The origin‐based algorithm is embedded into the augmented Lagrangian method for the link‐capacitated traffic assignment problem. In order to solve the “nonexistence” problem due to the second partial derivatives of the augmented Lagrangian function at some specific points, the approximate expressions of the second partial derivatives are amended in the origin‐based algorithm. The graph of last common nodes is developed on the basis of the restricted single‐origin network. A method is proposed for finding n–1 last common nodes of the restricted single‐origin network, resulting in computational complexity of O(n²) in finding last common nodes. Numerical analysis on the Sioux Falls network and Chicago Sketch network demonstrated the effectiveness and characteristics of the proposed algorithm. Copyright © 2014 John Wiley & Sons, Ltd.