5.1 Sudden changes

The third category of thermal effects identified in Section 2 are those associated with sudden changes. Here are some technically important examples where things change suddenly at a particular temperature:

  • Pure water boils at 100 °C (at atmospheric pressure).<
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4.4 Summary of Section 4

  • Thermal energy is a random thing, so any group of particles possessing it will have a distribution of kinetic energies.

  • The fraction of particles with energy greater than an amount E1 is proportional to exp(−E1/kT).

  • Thermally activated rates follow Arrhenius's law and are characterised by an activation energy.

  • Diffusion in solids and electrical conduction i
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6.5 RSS

RSS (‘Really Simple Syndication’ or ‘Rich Site Summary’) newsfeeds supply headlines, links, and article summaries from various websites. By using RSS ‘feedreader’ software you can gather together a range of feeds and read them in one place: they come to you, rather than you having to go out and look for breaking news. The range of RSS feeds on offer is growing daily. There is probably a feed to cover all aspects of your life where you might need the latest information, and you may
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2.3.3 The matrix team

In a matrix team, staff report to different managers for different aspects of their work. Matrix structures are often, but not exclusively, found in projects. Staff will be responsible to the project manager for their work on the project while their functional line manager will be responsible for other aspects of their work such as appraisal, training and career development, and ‘routine’ tasks. This matrix project structure is represented in Figure 2.


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4.1 Understanding the polymerization process

Converting monomer to long chain polymer is the final step in the polymer manufacturing sequence. Polymerization is usually highly favourable in thermodynamic terms, mainly on energetic grounds because ordering molecules into linked chains is a process where the entropy is decreased. Heat is always given out during polymerization owing to the very favourable energetics of reaction, a point you may have noticed if you have ever made GRP parts for your car, for example!

Advances in cataly
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3.3 Petrochemical intermediates and monomers

About 80 per cent of all petrochemicals end up in polymers, the most important building blocks being ethylene, propylene, butadiene and benzene. The first three can be polymerized directly but an important slice of their production is used to create more complex monomers. Ethylene is the progenitor of most vinyl monomers (Figure 3
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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.


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References

IEC 60793-2-10 (1992) International Standard 60793-2-10 Optical Fibres – Part 2-10: Product Specifications – Sectional specification for category A1 multimode fibres, International Electrotechnical Commission.
IEC 60793-2-50 (1992) International Standard 60793-2-10 Optical Fibres – Part 2-;50: Product Specifications – Sectional specification for category B single mode fibres, International Electr
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Appendix 1 Terminology

After studying this unit you should be able to explain the meaning of the following terms:

all-optical network

angle-polished convex connector

bandwidth-distance product

chirp

combiner

connector

continuous wave operation

dense wavelength division multiplexing

direct modulation directional coupler dispersion

dispersion compensation dispersion-shifted fibre electro-optic material excess loss external modulation extinction ratio four-wa
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3.2 Directional couplers

A simple yet valuable device is the directional coupler (Figure 19). A directional coupler can be constructed from two single-mode fibres by bringing them into close contact and heating so that the glass melts and the two fibres fuse. Light can then pass from one fibre to the ot
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2.4.2 Dispersion in single-mode fibre

Because there is only one mode in single-mode fibre, there is no multimode distortion but pulses are spread by dispersion.

Dispersion is the effect of different frequencies propagating at different speeds, and there are various mechanisms in optical fibre which mean that in general a fibre is dispersive. Given that dispersion takes place, a transmitted pulse will be spread because different frequency components in the pulse will take different lengths of time to propagate
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Introduction

This unit is adapted from the Open University course Business operations: delivering value (T883_1), which is about the essence of any enterprise – that core set of processes needed to convert various resources (such as materials, money and the effort of people) into outputs (such as manufactured goods and/or delivered services) that provide value to customers and other stakeholders. T
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2 Specifications for image capture

This section is about the performance specification for a captured image. Cameras do not attempt to copy the way in which light signals are detected and processed by nerve cells in the eye – the latter is based on quite different principles from those we have seen here, using changes in molecular shape within proteins to detect light and initiate a response.

Photography began as a means of capturing images that the human eye would have seen. That task involves obtaining full-colour i
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1.3 The capacity of an MOS structure to store charge

Figure 1 shows a schematic section through an MOS structure and sets up a colour scheme that distinguishes the different layers. In this case the M-layer is provided by heavily doped polysilicon and the semiconductor base material is p-type silicon.


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2.3 Berliner experiments with plates

Emile Berliner was a young German immigrant to the USA with an interest in science. Whilst working in several menial jobs he educated himself in basic physics and chemistry, eventually building a small laboratory at his boarding house. Experiments with electricity and acoustics led to his invention of a new telephone transmitter, which he sold, enabling him to set up as a full-time inventor. He became interested in recording sound through studying a device called the phonoautograph. This appa
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3.2 Summary

The number of cycles of oscillation per second, both for a vibrating source and a pressure wave, is known as the frequency, symbol f Frequency is specified in hertz (Hz) or kilohertz (kHz). One hertz is one cycle per second; one kilohertz is one thousand cycles per second. Frequency and period are directly related. Frequency is the reciprocal of period:

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2.3 Pressure waves and cycles

In this section we shall be looking at the behaviour and properties of pressure waves in the atmosphere.

Sound originates from the motion or vibration of an object. Let's look at an example of a sound wave generated by a vibrating tuning fork. The prongs of the tuning fork move backwards and forwards cyclically. A cycle is a complete series of movements up to the point where the movement starts to repeat itself. As the prongs of the fork vibrate back and forth they push on neighbouring
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2.2 Pressure in the atmosphere

The sounds we hear generally consist of rapid fluctuations of air pressure in the atmosphere that surrounds us. Sound can also be transmitted through other media, for instance water, so not all sound consists of fluctuations in air pressure. However, for the purposes of this discussion I shall confine myself to sound in air.

These fluctuations in air pressure are caused by a local disturbance to the air pressure, which might be sudden and transient – for example, when a paper bag is b
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5.1 Introduction

In this section, I shall explore the features of the contextualising (systems-methods) ball – the C ball. I will make a distinction between systemic and systematic thinking and action and I will argue that the aware systems practitioner has more choices than the practitioner who is not aware.

An aware practitioner is able to contextualise a diverse array of methods at their disposal creating an opportunity for a greater range of advantageous changes in the ‘real world’ situation.
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4.2 Articulating your appreciation of complexity

Initially, I would like you to notice whether and how your appreciation of the phrase ‘managing complexity’ has changed since you started the unit. As you work through Section 4 you will encounter a number of ways of thinking about complexity that may be new to you, so it becomes important to record your developing understanding. To help you with this, return to your notes on Author(s): The Open University