Stage 5: Formulating measures of performance (how will we know when we have arrived?)

The hard systems approach emphasises the need to have measurable means of assessing the efficacy of any potential solution or design, but recognizes that this may not always be possible.


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Stage 4: Generation of routes to objectives (how could we get there?)

This stage explores the different ways of achieving the defined objectives. It is the most imaginative and free-thinking stage of the approach. The idea is initially to generate as many ideas as possible, then to whittle the list down to two or three ‘definite possibilities’ that can be carried further in the development stage.

Stage 3: Identification of objectives and constraints (where would we like to be?)

This stage forces the project team to make explicit the objectives and constraints associated with the problem or opportunity. This is valuable for several reasons.

  • It forces everyone concerned to clarify what they hope to achieve.

  • The need to agree objectives and constraints can bring into the open disagreements that otherwise might emerge only at a later stage of the approach.

  • The process of defining, elaborating an
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Stage 2: Analysis of the existing situation (where are we now?)

Having defined and agreed on the problem, it is necessary to decide on the system in which you consider it plays a part. In practice the two stages are closely linked and the analysis of the existing system nearly always means a redefinition or refinement of the problem or opportunity. Identifying and defining the problem and the system or systems that relate to it are critical for the success of subsequent analysis.

Stage 1: Problem definition (what is the problem?)

The aim of the first stage is to identify and describe the problem or opportunity. While each stage depends on the success of the previous stage, it is the initial stages of a project that set the direction for the work as a whole. For this reason a clear definition and firm agreement on the problem or opportunity are essential.

Problems and opportunities are like two sides of a coin: one of them can always be formulated in terms of the other. The best way to distinguish between them is
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3.8 Systems methodologies for managing change: hard systems approach

The stages of the hard systems approach are illustrated in Figure 34 and simplified in Figure 35. The model shown in these figures was developed by the Open Systems Group from earlier work by de Neufville and Stafford (1974). The stages ‘problem/opportunity’ and ‘implementation’ are shown in solid boxes because they occur in the real wor
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3.7 Systems methodologies for managing change

The use of systems concepts and models forms part of a process of investigation that is often described in the literature of systems, design and decision-making as a ‘methodology’, where a methodology is a process of enquiry, not a method to produce a predetermined result.

A systems methodology has the following characteristics.

  • It is, or it provides, the means for the investigator to draw up a plan for studying a situation. This encour
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3.6 Systems concepts: dynamic behaviour: control

A system does not usually behave in a random manner – its actions are governed in some way. This can be achieved by using the control models, either singly or in combination, shown in Figure 32(a) and (b). The feedback (or closed loop) control model in Figure 32(a) works as follows:

  • a feature of the output from
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3.5 Systems concepts: dynamic behaviour: input-transformation-output

Utilitarian systems, as previously discussed, are the means we use to transform resource inputs into useful goods and services. Any system can be divided into a set of input-transformation-output blocks. These are usually represented as in Figure 31. This way of looking at systems can be used as an analytical and design tool.


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3.4 Systems concepts: structure

As suggested earlier, the structure of a system is its functional or physical arrangement; the term that is often used in systems engineering is ‘architecture’. The architecture of a system can be deconstructed to reveal its constituent elements. I suggested in Section 1 that an existing knowledge base has an important bearing on the way in which a change problem is perceived. The way that this is conceived by one armaments system integrator is illustrated in Author(s): No creator set

3.3 System concepts: holism

One of the distinguishing features of the systems approach is its attempt to be holistic – to include all the elements in the picture at each level at which the system operates. The premature exclusion of important elements can be dangerous and can lead to, for example:

  • a purchasing manager being so keen to drive down raw material and component costs that he or she causes quality and production problems in construction of the system


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3.2 Systems concepts: system

The word ‘system’ is from the Greek word meaning a complex, organised whole. It has been used in this sense throughout history, and the Oxford English Dictionary records examples of usage dating from the early eighteenth century. Figure 24 shows a simplified diagram of a typical system. It indicates the boundary of the system,
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3.1 Introduction

As you would expect, since this unit deals with systems engineering, it embodies the principles and methods associated with a systems perspective. So it is important that you understand systems and the systems perspective at the beginning of the unit.

To have engineered a system successfully, all its features – the technology, control systems, people and related aspects of the physical environment – have to contribute to the achievement of its objectives. In other words, it h
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2.3 Summary and conclusions

This topic has addressed the question ‘What is modern engineering?’ The conclusion must be drawn that, until recently, engineers were content with fairly simplistic definitions of their profession, thinking that it consisted of little other than craft skills or practical experience grafted on to a knowledge of mathematics and appropriate natural sciences. It has been methodologically naive, and definitions of the processes of engineering either lack detail (Author(s): No creator set

2.2 A modern view

Modern attempts to define engineering recognise the importance of the resources identified by Sage, and that the subject can be divided into two components: engineering knowledge – the ‘know-what’, and engineering process – the ‘know-how’. Engineering knowledge is:

[…] the growing body of facts, experience and skills in science, engineering and technology disciplines; coupled to an unde
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2.1 The development of engineering

Engineering is one important component of systems engineering. In this topic I will examine the development of engineering before presenting a modern view of the subject. Section 3 will then pick up and discuss the idea of systems engineering.

William Shipley, a drawing master from Northampton, was instrumental in founding ‘the Society Instituted at London for the promotion of Arts, Manufactures and Commerce’ in 1754. This later became the Royal Society for the encouragement of
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1.9 Increasing complication, complexity and risk: summary

The three levels of change problem, simplicity, complication and complexity, can be associated with craft, engineering and systems engineering knowledge. The three categories of change problem represent different levels of uncertainty of what needs to be done and how to do it. The greater uncertainty brings increased risk. Although we tend to be risk averse we will take on greater risk if the returns are commensurate with doing so.

Human experience can be divided into three worlds. The
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1.8 Increasing complication, complexity and risk: are systems becoming more complex?

Figure 17 shows the evolution of two commonly encountered applications of systems – for personal transport and for the reproduction of recorded music. In both cases the degree of complexity of the systems application has increased over time. One of the main reasons for this is technology push. The importance of technology can be related to the stages of the product life cycle shown in Author(s): No creator set

1.7 Increasing complication, complexity and risk: a spectrum of systems intractability

Summarising the discussion in the previous two sections, Figure 12 shows what might be termed ‘a spectrum of systems intractability’. At one end of the scale are simple systems. These are easily understandable and their design and development (relatively) unproblematic. The way in which the various elements in the system fit and work together is clear. Outputs and behaviours are predictable. An example of a simple
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1.5 Increasing complication, complexity and risk: the underlying relationship

Figure 3 showed five commonly encountered problems of effecting different types of change. These are notionally located on a spectrum of change that ranges from no change at all, to complete revolution. The relationship suggested on the figure is that as the degree of change – represented by the different types of problem – increases so, too, do difficulty and risk. Each of the five problems of effecting change can be r
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