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On Monitoring the topk Unsafe Places Presented by: Ling Hu College of Computer and Information Scien

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College of Computer and Information Science. Northeastern University, Boston, MA 02115 ... Police units patrol around and protect neighborhoods, how to ... – PowerPoint PPT presentation

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Title: On Monitoring the topk Unsafe Places Presented by: Ling Hu College of Computer and Information Scien


1
On Monitoring the top-k Unsafe Places Presented
by Ling Hu College of Computer and Information
ScienceNortheastern University, Boston, MA
02115audnyhu_at_ccs.neu.edu
We continuously monitor the most unsafe places in
a city
  • Problem
  • Police units patrol around and protect
    neighborhoods, how to efficiently find out places
    that are under-protected?
  • Continuous Top-k Unsafe Places (CTUP) query is
    to continuously monitor the k places with the
    smallest safeties (the difference between actual
    protection and required protection of the places).
  • Solutions
  • Basic Continuous Top-k Unsafe Places (BasicCTUP)
  • Experiments
  • Initialization Cost
  • Contributions
  • CTUP query is a novel addition to the family of
    continuous location-based queries. Solving this
    query may have a strong impact on the society.
  • It proposed two solutions to the CTUP query and
    an optimization to maintain the lower bounds of
    cells.
  • It evaluated the proposed schemes and revealed
    some insights on how to choose certain system
    parameters.
  • Update Cost
  • Drawbacks of BasicCTUP
  • Unnecessary lower bound decreasing
  • Too many places maintained in memory
  • Flashing cells increase cost
  • Optimized Continuous Top-k Unsafe Places
    (OptCTUP)
  • List of units decreased cells lower bound for
    each cell (DOO)
  • Maintain a small number of places (safety SK?)
  • All cells are dark, no flashing phenomenon
  • Model
  • A centralized server stores the map of the city,
    along with the required protection of every place
    in the city.
  • All police units report their position updates
    to the server.
  • The server gives up-to-date top-k unsafe places.
  • Effect of DOO optimization
  • Decrease Once Optimization (DOO)
  • For more information
  • http//www.ccs.neu.edu/research/dblab
  • Prof. Donghui Zhang donghui_at_ccs.neu.edu
  • Yang Du duy_at_ccs.neu.edu
  • Ling Hu audnyhu_at_ccs.neu.edu
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