Search

Accurate and fast path computation is essential for applications such as onboard navigation systems and traffic network routing. While a number of heuristic algorithms have been developed in the past few years for faster path queries, the accuracy of them are always far below satisfying. In this paper, we first develop an agglomerative graph partitioning method for generating high balanced traverse distance partitions, and we constitute a three-level graph model based on the graph partition scheme for structuring the urban road network. Then, we propose a new hierarchical path computation algorithm, which benefits from the hierarchical graph model and utilizes a region pruning strategy to significantly reduce the search space without compromising the accuracy. Finally, we present a detailed experimental evaluation on the real urban road network of New York City, and the experimental results demonstrate the effectiveness of the proposed approach to generate optimal fast paths and to facilitate real-time routing applications. [ABSTRACT FROM AUTHOR]

This study applied graph theory to conduct an empirical analysis of the evolution of global maritime container shipping networks, mainly focusing on the 1970s. In addition to analyzing the change in overall structures of the networks over the long term (from the 1970s to the present) and midterm (in the 1970s), the authors examined the changes in the container shipping networks before and after the reopening of the Suez Canal in 1975. As a result, it was confirmed that the initial single polar network structure, in which New York and other North American ports were placed at the center, changed to a multipolar structure, finally forming a hub-and-spoke structure. Subsequently, the authors confirmed discontinuous changes in inter-regional density from 1975 to 1976 caused by an increase in the average number of ports of call in 1976, because the recession caused by the first oil crisis in 1973 decreased the maritime container shipping demand, and the reopening of the Suez Canal caused a surplus of containerships. This study would contribute to accumulating empirical knowledge on the vulnerability analysis of the present and future maritime container shipping networks. [ABSTRACT FROM AUTHOR]

This article examines service coordination patterns across various service areas in Albany, the capital city of the New York State. Based on 42 in-person interviews with executive directors at various human service agencies, inter-organizational network was constructed and analyzed. The network displayed sparse and multipolar connectivity, suggesting that organizations operate in silos, with few organizations holding key positions of structural importance in the network architecture (so-called "super-connectors"). In addition, content analysis drew qualitative insights into perceived challenges to coordinate services. Several factors, both external (e.g., lack of trust or centralized communication system) and internal (e.g., lack of resources or knowledge) might have contributed to the observed structural properties. This finding suggests further examining the role of super-connectors in future research to better understand why these hubs exist and how they can work with other organizations in a cooperative and mutually beneficial manner. [ABSTRACT FROM AUTHOR]