Artificial neurons designs

A network is composed of units or simple named nodes, which represent the neuron bodies. These units are interconnected by links that act like the axons and dendrites of their biological counterparts. A particular type of interconnected neural net is shown in Fig. 5.12. In this case, it has one input layer of three units (leftmost circles), a central or hidden layer (five circles) and one output (exit) layer (rightmost) unit. This structure is designed for each particular application, so the number of the artificial neurons in each layer and the number of the central layers is not a priori fixed. 

Whenever talking about ANNs it is wise to stress first that in the phrase neural network the emphasis is on the word network rather than on the word neural. The meaning of this remark points to the fact that the way the artificial neurons are connected or networked together is much more important than the way each neuron performs its simple operation for which it is designed. 

The results obtained from the experimental studies confirm that the information-processing functions predicted by the pertinent analytical models can be achieved experimentally. Moreover, these results support the view that artificial biochemical neurons can be implemented in practice for informationprocessing purposes. Furthermore, because of the very high dependence of the system function on the internal parameters and the relations between them, the analytical models developed are essential tools for the engineering design of such systems as well as for determination of the operational parameters required for these systems to perform the information-processing function desired. 

Artificial neural networks (ANNs) are programs designed to simulate the way a simple biological nervous system is believed to operate. They are based on simulated nerve cells or neurons that are joined together in a variety of ways to form networks. These networks have the capacity to learn, memorize and create relationships amongst data [307-313] or chemical characteristics [314-319]. There are many different types of ANNs that can be used in environmental forensic investigations, but some are more popular than others. The most widely used ANN is known as the Back Propagation ANN. This type of ANN is excellent at prediction and classification tasks. Another is the Kohonen or Self... 

Microelectrode suuctures have been created that mimic aspects of brain function. Amatore and coworkers have described assemblies of paired microband electrodes that behave like a neuronal synapse (26). The generator electrode in these devices mimics a synaptic terminal, and the collector electrode functions as a postsynaptic membrane. These artificial synapses can be designed in several configurations to perform Boolean logical operations, such as AND or OR operations. 

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