一种基于MPLS-DiffServ流量工程的故障恢复模型

针对基于MPLS流量工程的本地、路径、重路由故障恢复模型存在资源利用率不高、恢复周期较长的缺点,提出了一种基于MPLS-DiffServ流量工程的故障恢复模型。该模型根据网络的故障发生概率、故障恢复时延的要求与网络资源利用率等参数和数据流分类进行配置,选择路径恢复算法。结果表明,该模型提高了资源利用率,缩短了故障恢复周期,对网络数据流故障恢复具有较强的有效性。     

Generation and recovery of airborne delays in air transport

The analysis of the causes behind the appearance and propagation of delays is one of the major topics inside Air Transport Management research. Existing research focuses by and large on Air Traffic Flow Management regulations and reactionary delays; less attention has been devoted to the study of the mechanisms governing the generation and absorption of delays while airborne, in spite of their important economical and environmental consequences. Here we present a methodology to detect delay-generating events, based on the comparison of planned and real trajectories; these events are then used to characterise several aspects of the dynamics of the system, e.g. its resilience. We apply this methodology to a historical data set of flights crossing the European airspace during 2011, and observe an overall resilient system, able to absorb as much delays as it generates; yet resilience is not constant, but strongly depends on the phase of the flight, and shows high spatial and temporal heterogeneities. We anticipate the proposed methodology to open new doors for the development of a better systemic performance, by enabling the characterisation and understanding of this fundamental type of delay.     

Operational analysis of the contraflow left-turn lane design at signalized intersections in China

The primary objective of the study was to evaluate the impacts of an unconventional left-turn treatment called contraflow left-turn lane (CLL) on the operational performance of left-turn movement at signalized intersections. An analytical model was developed for estimating the capacity of left-turn movement at signalized intersections with the CLL design. The capacity model was calibrated and validated using field data collected at six approaches at five signalized intersections in the city of Handan, China. The results of field data analyses showed that the use of CLL design improved the capacity of left-turn movements. However, the capacity gains with the CLL design were quite stochastic considering the randomness in the arrivals of left-turning vehicles. Analytical delay models were proposed for estimating the delay to left-turning vehicles at intersections with the CLL design. A procedure was also proposed for optimizing the location of the upstream median opening and the green interval of the pre-signal. Simulation analyses were conducted to compare the delay experienced by the left-turning and through vehicles at signalized intersections with the conventional left-turn lane, the CLL and another unconventional left-turn treatment entitled “tandem design”. The results showed that both CLL and tandem designs outperformed conventional left-turn lane design; and the CLL design generated less delay to both the left-turning and through vehicles as compared with the tandem design.     

The punctuality performance of aircraft rotations in a network of airports

The aim of this paper is to investigate the influence of aircraft turnaround performance at airports on the schedule punctuality of aircraft rotations in a network of airports. A mathematical model is applied, composed of two sub-models, namely the aircraft turnaround model (turnaround simulations) and the enroute model (enroute flight time simulations). A Markovian type model is featured in the aircraft turnaround model to simulate the operation of aircraft turnarounds at an airport by considering operational uncertainties and schedule punctuality variance. In addition, stochastic Monte Carlo simulations are employed to carry out stochastic sampling and simulations in both the aircraft turnaround model and the enroute model. Results of simulations show the robustness of the aircraft rotation model in capturing uncertainties from aircraft rotations. The propagation of knock-on delays in aircraft rotations is found to be significant when the short-connection-time policy is used by an airline at its hub airport. It is also found that the proper inclusion of schedule buffer time in the aircraft rotation schedule helps control the propagation of knock-on delays and, therefore, stabilize the punctuality performance of aircraft rotations.     

Stakeholder Collaboration and Organizational Innovation in the Planning of the Deschutes Estuary Feasibility Study

Coastal managers have sought to enhance the collaborative inputs of stakeholder groups into management activities. Nonetheless, established organizational approaches have led to primarily consultative forms of engagement and constrained citizen involvement in formative activities. In Olympia, Washington, managers overseeing the Deschutes Estuary Feasibility Study (DEFS) implemented an innovative cooperative research planning initiative that diverged from conventional consultative processes. Stakeholders, rather than government officials, identified the research priorities for the socioeconomic component of this restoration feasibility study. This design method altered the traditional roles and responsibilities of different organizational actors, and the involvement of citizen groups in these formative activities changed the relationship between governmental and nongovernmental actors. Using conceptual frameworks from organizational sociology, this study develops insights into the behavior of the organizations involved with the DEFS cooperative planning effort, demonstrating how engaging stakeholders in formative research planning activities may foster new types of collaboration among coastal management organizations.     

基于小波融合的车牌模糊图像复原算法

为了更有效的实现交通信息采集,提出了一种基于小波融合的车牌图像超分辨率方法.首先分析了低分辨率图像的降质原因,主要降质因素包括:图像的形变、模糊和欠采样,根据这些降质因素建立了降质模型,分析降质模型,得出本文方法的理论模型.然后针对交通图像的特点,对形变、模糊和欠采样3个问题进行探讨,得出主要参数的估计方法.并对小波融...     

山区河流泥石流灾害防治技术研究

为改善通航条件、提高航道等级,对山区河流泥石流灾害防治技术进行了研究.根据形成机理、运动规律、成灾机制、岸坡的地形地貌特点,把山区河流型泥石流分为坡面流和沟谷流;基于土质结构原理与岩土稳定理论,提出了修复植被、规范人类行为与截流排水、拦粗排细、转向导流等工程防治技术相结合的山区河流泥石流灾害的综合防治技术.结果表明,该...     

硬质河底生态修复方案分析——以友谊河为例

对河流硬质护坡、护底进行生态修复已成为目前我国城市河流生态修复的研究热点、难点之一.以南京市友谊河为例,探讨硬质河底生态修复方式,讨论增氧设备、人工浮床、沉水植物的设计要点,为同类河道生态修复工程提供科学的依据和建议.     

Successful Transplantation of a Fragmenting Coral,Montipora digitata,for Reef Rehabilitation

The scleractinian coral Montipora digitata (Acroporidae) is a common reef flat species that thrives under high levels of light and water turbulence, and propagates successfully by natural fragmentation. It was used for transplantation experiments in an attempt to restore a degraded lagoon environment in the northwestern Philippines. Branches about 5 cm high from a natural population in the lagoon were transplanted to dead coral outcrops or knolls in two locations (Binlab and Malilnep-Ac) with different environmental characteristics. Growth and survival were significantly better at Malilnep Ac, which resembled the natural habitat of the species more closely. Environmental conditions at this site also favored the establishment of a greater diversity of species around the coral transplants. There was no difference in performance between transplants on vertical and horizontal surfaces, and the transplants showed limited differences due to density within the experimental range. Significant survival of detached, transplanted colonies or fragments thereof around the bases of the experimental bommies at the more successful site was an additional positive outcome. Water motion showed significant effects on survival and growth, possibly enhancing the suitability of the more successful site for transplantation. These results demonstrate the potential of coral transplantation to initiate the establishment of natural communities in degraded reef areas, a concern for coastal managers in developing countries.     

Book reviews

THE SEVENTH AUSTRALIAN TRANSPORT RESEARCH FORUM, by K. W. Ogden.

AIRLINE PLANNING: CORPORATE, FINANCIAL AND MARKETING by Nawal K. Taneja. Lexington, Mass., Lexington Books, 1982. 207 pp. (£19.50)

SOLVING LOCAL GOVERNMENT PROBLEMS: PRACTICAL APPLICATIONS OF OPERATIONS RESEARCH IN CITIES AND REGIONS, by Charles E. Pinkus and Anne Dixson. George Allen and Unwin, London, 1981. (Hardback £20.00; paperback £8.95)

SCIENTIFIC MANAGEMENT OF TRANSPORT SYSTEMS, edited by N. K. Jaismal. Published by North‐Holland Publishing Company (U.S. $58.50)

TRANSPORTATION AND TRAFFIC ENGINEERING HANDBOOK (Second Edition), edited by W. S. Homburger, Englewood Cliffs, N.J., 1982. Prentice Hall, pp. 883.

ECONOMICS OF PUBLIC TRANSPORT, by C. A. Nash. Longman, London, pp. 194. (£6.95).