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The Development of Neural Network Based System Identification ...

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28 CHAPTER 2 LITERATURE REVIEW<br />

1. Dendrites: Accept Inputs<br />

3. Axon: Turn the<br />

processed inputs<br />

to outputs<br />

Direction <strong>of</strong><br />

signal transmission<br />

Nucleus<br />

2. Cell Body/Soma:<br />

Process the Inputs<br />

4. Axon terminal buttons:<br />

<strong>The</strong> electrochemical<br />

signal transfer point<br />

Figure 2.5<br />

A simplified representation <strong>of</strong> a biological neuron.<br />

NN architecture such as Multi-layered Perceptron (MLP) network has been theoretically<br />

proven to be an universal approximator, thus capable <strong>of</strong> approximating any non-linear<br />

function <strong>of</strong> interest to any desired degree <strong>of</strong> accuracy with sufficiently available neurons<br />

[Hornik et al., 1989]. Furthermore, the NN models are also able to establish the required<br />

input-output relationship without a priori assumptions about the properties <strong>of</strong> the data<br />

or the governing mathematical models as in first principle modelling [Abas et al., 2011].<br />

<strong>The</strong> NN modelling approach has been used to perform a diverse range <strong>of</strong> tasks<br />

including prediction, function approximation, pattern classification and clustering. It<br />

has been proven in many research investigations and industrial applications as an<br />

efficient tool to handle complex input-output mapping. Paliwal and Kumar [2009]<br />

carried out a comprehensive literature review <strong>of</strong> over 100 comparative studies on the<br />

ANN and traditional statistical techniques used for prediction and classification tasks in<br />

various fields <strong>of</strong> applications. <strong>The</strong> review clearly highlights the potential and usefulness<br />

<strong>of</strong> the NN approach to approximate any non-linear mathematical function when it is<br />

difficult to handle the task statistically. It can be concluded from the review that NN<br />

models outperform the traditional statistical methods in most <strong>of</strong> the cases or at least<br />

performed as well as other statistical methods.<br />

<strong>The</strong> literature also includes numerous applications <strong>of</strong> NN to address a wide range <strong>of</strong>

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