tailieunhanh - Micro Electronic and Mechanical Systems 2009 Part 15

Tham khảo tài liệu 'micro electronic and mechanical systems 2009 part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Neuron Network Applied to Video Encoder 481 Fig. 3. Basic component of neural network Dendrites are inputs into neuron. Natural neurons have even hundreds of inputs. Point where dendrites are touching the neuron is called a synapse. Synapse is characterized by effectiveness called synaptic weight. Neuron output is formed in a following way signals on dendrites are multiplied by corresponding synaptic weights results are added and if they exceed threshold level on the result is applied a transfer function of neuron which is marked f on a figure. Only limitation of transfer function is that it must be limited and nondecreasing. Neuron output is routed to axon which by its branches transfers result to dendrites. In this way output from one layer of network is transferred to the next one. In neural networks three types of transfer functions are presently being used jumping logical with threshold sigmoid All three types are shown in figure 4 Fig. 4. Three types of transfer functions The neural network has unique multiprocessing architecture and without much modification it surpasses one or even two processors of von Neumann architecture characterized by serial of sequential information processing . Teeuwsen at all 2003 . It has ability to explain every functional dependence and to expose a nature of such 482 Micro Electronic and Mechanical Systems dependence with no need to external incentives demands for building a model or its change. In short neural network may be considered as a black box capable of predicting output pattern or a signal after recognizing given input pattern. Once trained it may recognize similarities when a new input signal is given which results in predicted output signal. There are two categories of neural networks artificial and biological ones. Artificial neural networks are in structure function and in information processing similar to biological ones. In computer sciences neural network is an intertwined network of elements that processes .