Brief Encounter Networks Vassilis Kostakos Oxford University, 16 - - PowerPoint PPT Presentation

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Brief Encounter Networks Vassilis Kostakos Oxford University, 16 - - PowerPoint PPT Presentation

Apr 20, 2023 326 likes •764 views

Brief Encounter Networks Vassilis Kostakos Oxford University, 16 October 2007 Motivation Understand the affordances of peoples mobility, and identify opportunities for pervasive systems Overview Data collection

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Brief Encounter Networks

Vassilis Kostakos

Oxford University, 16 October 2007

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Motivation

  • Understand the “affordances” of people’s

mobility, and

  • identify opportunities for pervasive systems
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Overview

  • Data collection
  • Structural properties
  • Dynamic properties
  • Diffusion
  • Ongoing work
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Data collection

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time

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Timeline view

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Gatecount timelines

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Gatecounts

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Bluetooth visibility

  • Around 7.5% of observed pedestrians had discoverable

Bluetooth devices

(R^2 = 0.88)

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Structural properties

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Scanner 4 1 6 3 2 5 1 2 3 4 6 5

time

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Dynamic properties

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Dynamic properties

  • Our data is not static
  • 3D structure
  • Chain of events
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Presence Frequency Nodes Links

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Model

  • Fixed population size n
  • Each node assigned probability f and p
  • At each iteration, node is activated with

probability f

  • If a node is activated, it remains active for p

times length of previous inactivity

  • If two nodes are simultaneously active, they

are linked to each other

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1 1

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Diffusion

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Chain of events

  • John, Mary, 14:20:30
  • John, Paul, 14:20:32
  • Mary,Nick, 14:20:33
  • ...
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Emulation

  • Class “device”
  • Class “virus”
  • During encounter, virus is transmitted
  • Device recovers (SIS) or dies (SIR)
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Remove Brief Encounters Remove Persistent Encounters

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Remove Brief Encounters Remove Persistent Encounters

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Ongoing work

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DTN forwarding algorithm

  • Static features
  • Node degree
  • Node betweenness
  • Node closeness
  • Average geodesic path (Bath = 3.3)
  • Community detection (21 using Newman)
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Considering time

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Game of real life

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Tamagotchi

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facebook People with Bluetooth devices bumping into each other (shopping, school, work) Cityware servers analyse data Cityware Facebook application presents data Cityware nodes record & upload data Users' social network grows

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New challenges

  • Best utilisation of this platform?
  • Create a “world socio-map”?
  • Develop adaptable systems
  • Develop more secure systems
  • Put numbers on human relationships
  • Put numbers on “fabric of everyday life”
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Thank you

Vassilis Kostakos vk @ cs. bath. ac. uk http :// www. cityware. org. uk