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Selective omission in a road network is a necessary operation for road network generalization. Most existing selective omission approaches involve one or two geometric parameters at a specific scale to determine which roads should be retained or eliminated. This study proposes an approach for determining the empirical threshold for such a parameter. The idea of the proposed approach is to first subdivide a large road network, and then to use appropriate threshold(s) obtained from one or several subdivisions to infer an appropriate threshold for the large one. A series of experiments was carried out to validate the proposed approach. Specifically, the road network data for New Zealand and Hong Kong at different scales (ranging from 1:50,000 to 1:250,000) were used as the experimental data, and subdivided according to different modes (i.e. administrative boundary data, a regular grid of different sizes, different update years, and different road network patterns). Not only geometric parameters, but also structural and hybrid parameters of existing selective omission approaches were involved in the testing. The experimental results show that although the most appropriate thresholds obtained from different subdivisions are not always the same, in most cases, the appropriate threshold ranges often overlap, especially for geometric parameters, and they also overlap with those obtained from the large road network data. This finding is consistent with the use of different subdivision modes, which verifies the effectiveness of the proposed approach. Several issues involving the use of the proposed approach are also addressed. [ABSTRACT FROM AUTHOR]

A novel approach is suggested for reducing traffic conflicts in at-grade (2D) urban networks. Intersections without primary vehicular conflicts are defined as zero traffic conflict (ZTC) designs. A complete classification of maximal ZTC designs is presented, including designs that combine driving on the right side in some streets and driving on the left side in other streets. It is shown that there are 9 four-way and 3 three-way maximal ZTC intersection designs, to within mirror, rotation, and arrow reversal symmetry. Vortices are used to design networks where all or most intersections are ZTC. Increases in average travel distance, relative to unrestricted intersecting flow, are explicitly calculated for grid-networks of sizes 10 by 10, 10 by 20 and 20 by 20 nodes with evenly distributed origins and destinations. The exact increases depend primarily on various short-range conditions, such as the access to the network. The average distance increase in most cases examined is up to four blocks. These results suggest that there is a potential for the new designs to be relevant candidates in certain circumstances, and that further study of them is worthwhile. [ABSTRACT FROM AUTHOR]

Abstract: This research presents the application of intelligent computing models in Air Traffic Flow Management (ATFM). Firstly, multi-agent system in grid computing environment is applied to deal with the problem of ATFM synchronization. The developed system consists of software agents, which are implemented in a Computational Grid platform for congestions identification, conflicts resolution and agreements negotiation among the participating airports. A metric criterion, called Agent’s Balancing Standard (ABS), is used as a basic index to measure the effectiveness of reducing both the amount of communication among agents and the delay of flights. Secondly, a brief discussion about the Meta-Level Control model is introduced in ATFM issues to improve the efficiency of communication among the agents. The system is developed to analyze the traffic flow information received, identify its importance and process it in the most adequate order. [Copyright &y& Elsevier]

The article focuses on the role of multimedia services on the provision and personalization of grid-based infrastructures. It discusses the importance of high-speed networking and sophisticated multimedia compression for complete access of network-based multimedia services. It presents the need for service providers to distribute traffic control to assure an adequate quality of service (QoS) in case of simultaneous access of different users. It cites several possible benefits of leveraging grid technologies for multimedia services which include the aggregation of diverse and dispersed resources to enable collaborative resource management. It also presents a table that lists several popular multimedia services and their evolution from the traditional network services.

Grid computing is becoming the preferred basis for large-scale distributed computing and Internet applications. ShanghaiGrid launched in Shanghai, China is a grid infrastructure that aggregates several heterogeneous supercomputers, data centers and other applications scattered in different organizations in Shanghai. One of the major focuses in the ShanghaiGrid project is research and development of an intelligent urban traffic management system based on the ShanghaiGrid system software. The system software provides a platform in a service-oriented way for resource encapsulation and management, service scheduling and accounting, data aggregation and adaptive transmission, as well as service composition and reliability support. This paper presents the main components of the system software, and investigates key techniques for the implementation of ShanghaiGrid and the intelligent urban traffic management system, concentrating on grid transaction and workflow management. Finally, we propose a new wireless sensor network model and routing protocol characteristic to mobile vehicles for dynamical traffic data collection. [ABSTRACT FROM AUTHOR]