Grocery distribution plans in urban networks with street crossing penalties

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.

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Genetic Improvement of Routing Protocols for Delay Tolerant Networks

ACM Transactions on Evolutionary Learning and Optimization ◽

10.1145/3453683 ◽

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.

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Research on intervention methods for children’s street-crossing behaviour: Application and expansion of the theory of “behaviour spectrums”

Accident Analysis & Prevention ◽

10.1016/j.aap.2021.105979 ◽

2021 ◽

Vol 152 ◽

pp. 105979

Author(s):

Kang Jiang ◽

Yulong Wang ◽

Zhongxiang Feng ◽

Jianqiang Cui ◽

Zhipeng Huang ◽

...

Keyword(s):

Street Crossing

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