tailieunhanh - neural networks algorithms applications and programming techniques phần 3

Bây giờ chúng ta sẽ xem xét một số kỹ thuật mô phỏng ANS mô hình xử lý bằng cách sử dụng phương pháp lập trình thông thường. Sau khi trình bày những hướng dẫn thiết kế và mục tiêu mà bạn nên xem xét khi thực hiện mô phỏng hoạt động của mạng thần kinh của bạn, | Applications of Adaptive Signal Processing 71 Past signal Figure This schematic shows an adaptive filter used to predict signal values. The input signal used to train the network is a delayed value of the actual signal that is it is the signal at some past time. The expected output is the current value of the signal. The adaptive filter attempts to minimize the error between its output and the current signal based on an input of the signal value from some time in the past. Once the filter is correctly predicting the current signal based on the past signal the current signal can be used directly as an input without the delay. The filter will then make a prediction of the future signal value. Figure This example shows an adaptive filter used to model the output from a system called the plant. Inputs to the filter are the same as those to the plant. The filter adjusts its weights based on the difference between its output and the output of the plant. L 72 Adaline and Madaline magnetic radiation we broaden the definition here to include any spatial array of sensors. The basic task here is to learn to steer the array. At any given time a signal may be arriving from any given direction but antennae usually are directional in their reception characteristics They respond to signals in some directions but not in others. The antenna array with adaptive filters learns to adjust its directional characteristics in order to respond to the incoming signal no matter what the direction is while reducing its response to unwanted noise signals coming in from other directions. Of course we have only touched on the number of applications for these devices. Unlike many other neural-network architectures this is a relatively mature device with a long history of success. In the next section we replace the binary output condition on the ALC circuit so that the latter becomes once again the complete Adaline. THE MADALINE As you can see from the discussion in Chapter 1 the

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