Tuesday, September 30, 2014

Week 6: Computer Networks & Wireless Networks


  •          Local Area Network
  •      Interconnects computers within a limited area

    •        Initial driving force for networking was generally to share storage and printers
  •          Small geographic area
  •           Ethernet and WiFi are the two most common
  •          Early LAN cabling had been based on various grades of the coaxial cable          
    •     WiFi is now common for ‘cabling’
    •        Supports easy access for laptops and smartphones
  •          LANs can maintain connections with other LANs via leased lines, leased services, or the internet via the VPN

  •          Allows computers to exchange data
  •           The best known computer network is the internet
  •           Support access to the www, shared use of application and storage servers, printers, and fax machines and use of email and instant messaging applications

o   Facilitates interpersonal communications
o   Allows sharing of files, data, and other types of info
  •          Complex computer networks may be difficult and costly to set up
  •           Network packets

o   Info in computer networks is carried in packets
o   Formatted unit of data (bits or bytes)
o   The bandwidth of the communication medium can be better shared  among users
o   Consists of two types of data:
§  Control information
·         Provides data the networks needs to deliver the user data
§  User data

Management of RFID in Libraries (http://www.kcoyle.net/jal-31-5.html)
  •           RFID = radio frequency identifier
  •           Like a barcode, but is read with an electro-magnetic field rather than a laser beam

o   Does not have to be visible to be read
o   Carry more complex messages than a barcode
  •           There are hundreds of different RFID products on the market today

o   What varies is the amount of information the tag carries, the range in which it can be read, the frequency of its radio waves, its physical size, and the cost
-          Why RFID in libs?
o   Anyone managing an inventory of physical objects need to do item-level functions more efficiently and with less human intervention
o   RFID will probably continue to replace barcodes
  •          In retail, RFID tags are used only once (placed on an item, sold, and discarded by the customer)

o   This would be more cost effective for libraries because the same RFID tag would be reused multiple times (because it would be placed on a book, borrowed, returned, re-shelved, borrowed, returned, etc.)
  •           Security

o   Tags have ‘special security bit’ that can be switched from checked-in to checked out
§  Exit gates read each tag as users pass out of the lib
·         Sounds alarm if the bit is not in ‘checked-out’ state
o   Tags can be covered by Mylar, aluminum foil, or an aluminum gum wrapper
o   Tags are often found on the inside cover of a book, barely covered, and can be easily removed
  •           RFID systems can read multiple tags at once

o   Allows the checkout of multiple books in one transaction
  •          RFID could be used to gather statistics on re-shelving and completing inventory
  •           Could potentially tell a user exactly where an item is located


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