digital

• Peer-to-peer network


  • All nodes have equal status, nodes share their resources with one another
• Server-based network


  • One central node controls the network and its resources, other nodes request resources from the Server
• Peer-to-peer network


  • All computers have equal status, no dedicated Server, hardware and software resources are shared, each device on a P2P network is both a supplier and consumer of resources, resources such as processing power/disk storage can be shared and resources can be requested from other nodes
• Server-based network


  • Used in large organisations, at least one person performs the role of the file Server, file server activities include file Storage, file back up, providing application software and printer management, all computers are connected to the Servers by the Switch/hub, all users need a username + password to access the Server
• Bandwidth


  Transmission capacity of a communication channel
• Broadband


  High-speed internet access that is always on and faster than traditional dial-up access
• Transmission Media


  • Fibre optic
  • Metal
  • Wireless
• Parity bits


  Bits added to a data transmission to allow error detection
• Odd parity


  The parity bit is set to 1 if the number of 1s in the data is odd, so that the total number of 1s (including the parity bit) is odd
• Even parity


  The parity bit is set to 1 if the number of 1s in the data is even, so that the total number of 1s (including the parity bit) is even
• Error detection and correction using parity bits

  • Parity bits can detect errors but cannot correct them individually, Hamming code uses both horizontal and vertical parity checking to detect and correct errors
• Checksum


  A mathematical total appended to a data packet to allow error checking at the destination
• Echo checking


  The transmitted data is echoed back to the sender and compared to the original to detect errors
• CRC (Cyclic Redundancy Check)


  A special checksum appended to a block of data, calculated using a mathematical algorithm applied to the data block
• Relational database


  A database that stores data in tables with defined relationships between them
• Flat-file database


  A database that stores data in a single table with no defined relationships

  
• Logical data model


  A conceptual model of the data requirements of a system
• Physical data model


  A technical model of how the data will be stored and accessed
• Entity Relationship Model (ERM)


  A graphical representation of the entities in a database and the relationships between them
• Stages of database normalisation

  • 1NF
  • 2NF
  • 3NF
• Data dictionary


  A repository of information about the data in a database
• SQL (Structured Query Language)


  A programming language used to manage and manipulate relational databases
• QBE (Query by Example)


  A database querying method that allows users to create queries by filling in examples of the desired results
• Artificial Intelligence (AI)


  The study of machines to model the type of intelligence exhibited by people, enabling machines to learn and adapt to be more capable and improve human intelligence and cognitive behaviour
• Artificial Intelligence


  • Knowledge based or expert systems
  • Image processing
  • Speech recognition or natural language processing
  • Machine learning
• Turing test


  A test to determine if a machine's behaviour is indistinguishable from a human expert response
• Problems with the Turing test include the lack of speech output and the fact that it does not assess the correctness of the responses, only their similarity to a human expert
• Neural network model


  • Consists of a collection of nodes linked by one or two-way connections, each node calculates the weighted sum of its input and provides an output, backward propagation may be used
• Expert system


  An application of AI that makes the knowledge of a human expert available through a computer package
• Structure of an expert system

  • Requires a subject expert and a team of technical experts known as knowledge engineers, the initial stage is knowledge acquisition where the expert's knowledge is programmed into the system, this forms the knowledge base which is then consulted and interrogated by the inference engine, the user interface is used to communicate with the system
• Knowledge base


  Contains the human expert knowledge about the problem domain, including facts and rules
• Inference engine


  Applies the rules in the knowledge base to draw conclusions
• Expert system shell


  The software development environment for creating an expert system, containing the components like knowledge base and inference engine
• Heuristics


  Rule of thumb derived from human experience and intuition, rather than pure logic
• Fuzzy logic


  Uses probabilities instead of true/false logic, allowing decisions to be made with incomplete data
• Knowledge engineer


  Technical experts who obtain the facts and rules from the human expert and program them into the knowledge base
• Switching on a mobile phone

  • Mobile phones use low intensity microwave signals to transmit and receive voice & data, when switched on a mobile emits radio signals broadcasting its radio location to allow calls to be diverted to it
• Life insurance


  The life insurance experts will provide the knowledge of the industry they work in by describing their experiences/knowledge of life insurance and the rules and heuristics they use in calculating life insurance
• Advantages of expert systems for life insurance

  • Can calculate life insurance premium faster than a human expert
  • Expert advice is always available
  • Makes rational decisions without emotional overhead
  • Can be used as a training aid to increase the expertise of staff
• Disadvantages of expert systems for life insurance

  • Risk of over reliance on technology
  • Experts may become deskilled and follow the expert system and not follow their intuition
  • Every situation cannot be programmed, therefore, errors may be possible