Urban Networks in Ch'ing China and Tokugawa Japan.Gilbert Rozman

1975 ◽  
Vol 81 (3) ◽  
pp. 693-694
Author(s):  
Richard L. Edmonds
Keyword(s):  
Urban Networks

Urban network of China from the perspective of population mobility: Three-dimensional co-occurrence of nodes and links

2021 ◽  
pp. 0308518X2199781
Author(s):  
Xinyue Luo ◽  
Mingxing Chen
Keyword(s):  
Three Dimensional ◽  
Geographical Distance ◽  
Two Dimensional ◽  
Population Mobility ◽  
Urban Network ◽  
Urban Networks ◽  
Low Level ◽  
Medium Level ◽  
High Level ◽  
External Connections

The nodes and links in urban networks are usually presented in a two-dimensional(2D) view. The co-occurrence of nodes and links can also be realized from a three-dimensional(3D) perspective to make the characteristics of urban network more intuitively revealed. Our result shows that the external connections of high-level cities are mainly affected by the level of cities(nodes) and less affected by geographical distance, while medium-level cities are affected by the interaction of the level of cities(nodes) and geographical distance. The external connections of low-level cities are greatly restricted by geographical distance.

scholarly journals Genetic Improvement of Routing Protocols for Delay Tolerant Networks

2021 ◽  
Vol 1 (1) ◽  
pp. 1-37
Author(s):  
Michela Lorandi ◽  
Leonardo Lucio Custode ◽  
Giovanni Iacca
Keyword(s):  
Routing Protocols ◽  
Genetic Improvement ◽  
Ad Hoc ◽  
Delay Tolerant Networks ◽  
Unmanned Vehicles ◽  
Test Cases ◽  
Urban Networks ◽  
Delivery Probability ◽  
Apply Genetic ◽  
Delay Tolerant

Routing plays a fundamental role in network applications, but it is especially challenging in Delay Tolerant Networks (DTNs). These are a kind of mobile ad hoc networks made of, e.g., (possibly, unmanned) vehicles and humans where, despite a lack of continuous connectivity, data must be transmitted while the network conditions change due to the nodes’ mobility. In these contexts, routing is NP-hard and is usually solved by heuristic “store and forward” replication-based approaches, where multiple copies of the same message are moved and stored across nodes in the hope that at least one will reach its destination. Still, the existing routing protocols produce relatively low delivery probabilities. Here, we genetically improve two routing protocols widely adopted in DTNs, namely, Epidemic and PRoPHET, in the attempt to optimize their delivery probability. First, we dissect them into their fundamental components, i.e., functionalities such as checking if a node can transfer data, or sending messages to all connections. Then, we apply Genetic Improvement (GI) to manipulate these components as terminal nodes of evolving trees. We apply this methodology, in silico, to six test cases of urban networks made of hundreds of nodes and find that GI produces consistent gains in delivery probability in four cases. We then verify if this improvement entails a worsening of other relevant network metrics, such as latency and buffer time. Finally, we compare the logics of the best evolved protocols with those of the baseline protocols, and we discuss the generalizability of the results across test cases.

Mapping urban networks through inter-firm service relationships: The case of China

Urban Studies ◽  
2017 ◽  
Vol 54 (16) ◽  
pp. 3639-3654 ◽  
Author(s):  
Fenghua Pan ◽  
Wenkai Bi ◽  
James Lenzer ◽  
Simon Zhao
Keyword(s):  
Initial Public Offering ◽  
Service Provision ◽  
Professional Services ◽  
Future Research ◽  
Law Firms ◽  
Economic Activities ◽  
Urban Network ◽  
Urban Networks ◽  
Producer Service ◽  
Public Offering

Literature on how cities get connected through networks of firms has been increasing in recent years. In particular, advanced producer service (APS) firms are being widely used to build intra-firm linkages to establish urban networks. In contrast to studies applying intra-firm networks, this study proposes an alternative strategy to build urban networks based on inter-firm service provision relationships during the process of initial public offering (IPO) in which APS firms – including securities, law firms and accounting firms – provide professional services for firms aiming to be publicly listed. Based on service provision connections between APS firms and their clients, this study provides fresh insights on urban networks in China. The results show that Beijing, Shenzhen and Shanghai strategically hold dominant positions within Chinese urban networks and they are the lead command and financial centres within the country. Particularly, Beijing has overwhelmingly more influence over other cities. The urban networks are embedded in China’s unique institutional context where market and state power together have shaped these networks. Since the urban network is built up based on real economic linkages, the findings might have further implications for policy-making and could contribute to ongoing debates regarding financial centres in China. It implies that connections between firms based on real economic activities can be an effective way to construct urban networks in future research.

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