| Research Abstract |
In this research, we have investigated the competitive neural nets (CANs) from the following facets, and obtained successful results.
1. Synthesis and analysis of efficient incremental learning methods:
As a result of this research, we have fond out asymptotic optimality of the CANs, and synthesized incremental learning methods. From comparative study with the conventional BPN (back-propagation nets), RBFN (radial basis function nets) and SVR (support vector regression) which is famous for its very good performance in nonlinear regression, the CANs with the new learning methods developed in this research show the best performance in nonlinear function approximation for various nonlinear functions even when the data involves noise. The CANs with the new learning methods are also applied to rainfall estimation, speech recognition, nonlinear chaos prediction, etc. and we obtained very good results. Especially, in a rainfall estimation contest held by IEICE (Institution of electronics, infor
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mation and communication engineers), our result using the CAN have honored the second prize.
2. Application of the nets to model switching control:
We have applied the above methods to temperature control of RCA solutions for cleaning silicon wafers. The actual RCA cleaning system is dangerous and unstable because the solutions are highly concentrated sulfuric acid (H2SO4), hydrogen peroxide (H2O2), etc., so that it is hard to obtain good repeatability in verification experiments of the control. We in this research have developed the thermal model of the RCA cleaning system, which is done for the first time in the world, and utilized in a lot of numerical experiments where the model switching controller using the CANs is applied the numerical model of the RCA cleaning system for estimating the best control parameter values, and the controller finally are the real RCA system. We have also developed a real time simulator of the RCA system for comparative studies with the commercial controllers whose control algorithms are not open, and we have verified the efficiency of the present controller.
In this research, especially in modeling the RCA cleaning system, in the real experiments, and in the development of the real time simulator, a lot of helps of Komatsu Electronics Inc. have been very important. Less
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