4 Mobile and Ubiquitous computing 4.1 What are the main characteristics of a device belonging to a volatile system: (letter corresponding to the correct answer). a. limited access, high processing capacity, sensors and actuators. b. limited energy, resource constraints, sensors and actuators. c. high storage capacity, high disk throughput. d. low cost, internet connectivity. 4.2 An example of a pre-configured association is: (letter corresponding to the correct answer). a. mobile system. b. ubiquitous system. c. email client and server. d. peer to peer file-sharing application. 4.3 The relevant forms of volatility in mobile and ubiquitous systems do not include: (letter corresponding to the correct answer). a. failures of devices. b. failures of communication links. c. changes in the characteristics of communication. d. unstable number of users e. creation and destruction of associations. 4.4 What are the main factors which contributed to the appearance of Mobile and Ubiquitous computing: (letter corresponding to the correct answer). a. computer devices become cheaper; software interfaces were published. b. network communication standards were agreed and adopted; improvement in the responsiveness and computational throughput of distributed systems c. devices become smaller; wireless connectivity becomes more prevalent. d. effective techniques for dealing with failures were developed; improvement in the responsiveness and computational throughput of distributed systems. 4.5 In Mark Weiser's vision of ubiquitous computing, computers will disappear from conscious thought. Explain Mark Weiser's vision