Systems practice: Managing sustainability
This free course, Systems practice: Managing sustainability, introduces ways in which systems thinking can help support processes of decision making amongst stakeholders with different, often contrasting, perspectives on sustainable development in order to generate purposeful action to improve situations of change and uncertainty. You will learn about systems practice for managing sustainable development, and find out how 'learning systems' are designed for purposeful action in the domain of sus
Digital communications
Optical-fibre communications became commercially viable in the 1970s and innovation continues today. This free course, Digital communications, will illustrate how very high data rates can be transmitted over long distances through optical fibres. You will learn how these fibres are linked, examine the technology used and assess the future direction of this continually developing area of communication.
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Introduction This key skill develops your information technology (IT) skills in your studies, work or other activities over a period of time. To tackle all of this key skill, you will need to plan your work over at least 3–4 months to give yourself enough time to practise and improve your skills, to seek feedback from others, to monitor your progress and evaluate your strategy and present outcomes. Skills in information technology cover a broad range, from using software unitages to developing a c
Managing complexity: A systems approach – introduction
Do you need to change the way you think when faced with a complex situation? This free course, Managing complexity: A systems approach introduction, examines how systemic thinking and practice enables you to cope with the connections between things, events and ideas. By taking a broader perspective complexity becomes manageable and it is easier to accept that gaps in knowledge can be acceptable.
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Design thinking
Are you ever frustrated with something that you thought you could design better? Design thinking can structure your natural creativity to come up with solutions to all kinds of problems, and have fun in the process too! First published on Thu, 22 Dec 2011 as Author(s):
Systems thinking: Understanding sustainability
This free course, Systems thinking: Understanding sustainability, introduces ways in which systems thinking can help support processes of decision making among stakeholders with different, often contrasting, perspectives on sustainable development in order to generate purposeful action to improve situations of change and uncertainty. You will be encouraged to engage with the concept of sustainable development, and discover and contextualise your own sustainable development beliefs and values.
4.3 Character code functions Many programming languages provide two functions associated with the character codes (see Table 2). We shall call these functions ASC and CHR. ASC takes a character as input, and returns the integer giving the ASCII code of the input character. CHR returns the character whose ASCII code is the input integ
4.1 Functions A function is a process that, when given an input of a specified type, yields a unique output. This is a key idea in providing a precise, mathematical, description of processes in computing. To describe a particular function, we first give the set from which the input will be drawn and the set from which the output is drawn. This information is called the signature of the function. An example will make this clearer. Author(s):
Objectives for Section 3
After studying this section you should be able to do the following.
Recognise and use the terminology: disjoint union; power set (of a set); representation (of a data abstraction). Use and interpret the notation: Â
X
3.2 Combining data structures In Section 2, we introduced the notation SeqOfX for the set of all sequences whose members come from the set X. In Section 2, we looked only at sequences whose members were of one of the primitive forms of data (integers, characters or Booleans). We can have sequences whose members are themselves data with a more complicated form. For example, suppose that Jo is working at the till T1 and is replaced by Jessica. We might represent this handover by the 3-tuple (Jo, T1, Jes
Module team David Reed (Chair and author) Jill Alger (Editor) Chris Bissell (Critical reader and author) Philippa Broadbent (Print buyer) David Chapman (Author) Daphne Cross (Assistant print buyer) Glen Darby (Graphic designer) Donna Deacon (Course secretary) Alan Dolan (Course manager) Roger Jones (Author) Jo Lambert (Learning projects manager) Roy Lawrance (Gra
The T822 course team
References 3.3 Hypertext transfer protocol (HTTP) In this section, I shall look at one example of an application of the TCP/IP protocol suite – sending hypertext pages over the world wide web (WWW or simply the web). However, first I shall very briefly summarise the main features of the web that are relevant to this discussion. There are many sources of information about the web on the web itself for those who want to know more. In very basic terms, the web is an application of the Internet for accessing resources where 3.1 What does TCP/IP protocol architecture do? The Internet is a worldwide public internetwork, which allows computers to communicate with each other even though they may have different manufacturers and different operating systems. The origins of the Internet lie in a project of the US Defense Advanced Research Project Agency in the 1970s, where it was intended to foster communication between research institutions rather than operate for profit. However, a substantial amount of traffic carried by the Internet is now related to com 2.4 Examples of layer functions There are several functions that can be performed at one or more of the OSI layers. Some of the more common ones are discussed below.
Connection control
For connection-oriented services, a connection must be established between peer entities. A connection has three phases: connection set-up, data transfer and connection clear. If the peer protocol supports connections, each protocol data unit type corresponds to a primitive type; for instance, a connection request primiti 1.2 Protocols in multi-service networks: introduction Early automatic telephone networks were built to carry only voice traffic and to provide a very simple telephone service – now called plain old telephone service (POTS). When computer networks started to appear, either they were separate from telephone networks or the data carried between computers was a small proportion of the traffic on the telephone network. There are various estimates for the growth of voice and data traffic, and various dates have been given for when data traffic will 5.3 Regaining meaning Suppose for a minute that the numbers I presented above were generated by a scanner as it produced a bitmap of a photograph. Clearly, the machine on which they are stored will have to get the image back to us by means of a device that can render it into a form meaningful to the human eye – an output device. I shall shortly review such devices. However, there is still work to be done before the computer can pass digitally-encoded data to such a device. For a start it will need to have 3.1 Ghosts of departed quantities They are neither finite quantities, or quantities infinitely small, nor yet nothing. May we not call them the ghosts of departed quantities? (Bishop G. Berkeley, The Analyst) This section follows up the ideas presented in and aims to: define the terms analogue, discrete and digital; look briefly at the human perceptual system, whic 2.4.4 Manipulation Suppose I take a digital photograph of myself for my website. Horrified by my wrinkled, baggy appearance, what can I do? Actually, with the right software I can do more or less anything I like: I can smooth out the wrinkles; I can restore the grey hair to its former splendour; I can even put in a background of books to give me a scholarly appearance. In fact, I can so improve the picture that if you met the real me you probably wouldn't recognise me. ‘Massaging’ my photographic imag 8.3 The AND operation The AND operation combines two binary words bit by bit according to the rules 0 AND 0 = 0 0 AND 1 = 0 1 AND 0 = 0 1 AND 1 = 1 In other words, only when both bits are 1 is the result 1. You may find it helpful to think of it this way: when one bit is one and the other bit is 1 the result is 1.
