73 research outputs found
Modeling Heterogeneous Relations across Multiple Modes for Potential Crowd Flow Prediction
Potential crowd flow prediction for new planned transportation sites is a
fundamental task for urban planners and administrators. Intuitively, the
potential crowd flow of the new coming site can be implied by exploring the
nearby sites. However, the transportation modes of nearby sites (e.g. bus
stations, bicycle stations) might be different from the target site (e.g.
subway station), which results in severe data scarcity issues. To this end, we
propose a data driven approach, named MOHER, to predict the potential crowd
flow in a certain mode for a new planned site. Specifically, we first identify
the neighbor regions of the target site by examining the geographical proximity
as well as the urban function similarity. Then, to aggregate these
heterogeneous relations, we devise a cross-mode relational GCN, a novel
relation-specific transformation model, which can learn not only the
correlations but also the differences between different transportation modes.
Afterward, we design an aggregator for inductive potential flow representation.
Finally, an LTSM module is used for sequential flow prediction. Extensive
experiments on real-world data sets demonstrate the superiority of the MOHER
framework compared with the state-of-the-art algorithms.Comment: Accepted by the 35th AAAI Conference on Artificial Intelligence (AAAI
2021
Search for light dark matter from atmosphere in PandaX-4T
We report a search for light dark matter produced through the cascading decay
of mesons, which are created as a result of inelastic collisions between
cosmic rays and Earth's atmosphere. We introduce a new and general framework,
publicly accessible, designed to address boosted dark matter specifically, with
which a full and dedicated simulation including both elastic and quasi-elastic
processes of Earth attenuation effect on the dark matter particles arriving at
the detector is performed. In the PandaX-4T commissioning data of 0.63
tonneyear exposure, no significant excess over background is observed.
The first constraints on the interaction between light dark matter generated in
the atmosphere and nucleus through a light scalar mediator are obtained. The
lowest excluded cross-section is set at for
dark matter mass of MeV and mediator mass of 300 MeV. The
lowest upper limit of to dark matter decay branching ratio is
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