摘要
随着现代信息技术的迅速发展,许多领域都积累了大量的数据。我们渴望发现潜在于这些数据中的知识与规律。正是这一需求造就了数据挖掘学科的兴起及数据挖掘技术的发展。作为一个多学科交叉的综合性领域,数据挖掘涉及了数据库、统计学、机器学习、高性能计算、模式识别、神经网络和数据可视化等学科。数据分类与预测作为一种重要的挖掘技术有着广泛的应用。在这一研究方向,目前已提出了多种分类方法(如决策树归纳分类、贝叶斯分类、神经网络分类和K-最邻近分类等)和一些预测技术(如线性回归、非线性回归等)。然而,尚未发现有一种方法对所有数据的处理都优于其他方法[1]。
由于时间序列数据库的日趋庞大及其挖掘的潜在意义,目前,时序数据挖掘研究已成为一个热点;然而,时间序列数据的非线性混沌特点,使得对它的挖掘成为难题。本文在分析与比较以上几种分类及预测方法的基础上,引入了径向基函数神经网络(Radial Basis Function Neural Network,简称RBFNN)对时间序列数据进行预测。在介绍该神经网络优点的同时,也阐述了其中较为棘手的难点。文中使用了层次遗传算法作为神经网络学习方法。在分析该方法可行性及效率的基础上,本文提出了用粗粒度并行方法进行径向基函数神经网络训练的思想,并建立了求解模型,旨在取得较好的预测效果。
最后,本文应用上述并行模型优化的RBF神经网络对非线性函数值以及证券个股收盘价进行预测。实验结果表明,当数据无噪声时,预测效率与精度都非常高;在处理带噪声,并呈现混沌特性的数据时,虽有一定的误差,但预测结果还是在可以接受的范围内。
With the rapid development of modern information technology, a great deal of data has been accumulated in many fields. People expect to discover the knowledge and rules existing in these data, which just brings the study of data mining and the development of its technology. As a comprehensive field of crossing multi-subject, data mining involved many subjects such as database, statistic, machine learning, high performance computing, pattern recognition, neural network and data visualization etc. Data classification and prediction are important mining technologies and have been used widely. Nowadays, many classification methods and some prediction technologies have been put forward, such as Classification by Decision Tree Induction, Bayesian Classification, Classification by Backpropagation, k-Nearest Neighbor Classifiers, Linear and Nonlinear regression. However, none of them is better than others in all application.
Because of the growing of Time-Series Database and the potential significance of data mining, the research of data mining in Time-Series Database has become a hotspot. At the same time, however, the nonlinear and chaotic characteristic of time-series data makes the mining be a difficult issue. Based on the analysis and comparison of these classification and prediction methods, this paper introduces a method that uses Radial Basis Function Neural Network (RBFNN) to make prediction for time-series data. As the advantage of this neural network is introduced, some hot potatoes are also discussed. This paper takes Hierarchical Genetic Algorithm as the neural network learning method. After analyzing the feasibility and efficiency of this method, we put forward an idea of using the coarse grained parallel method for Radial Basis Function Neural Network learning, and on purpose to get satisfactory prediction effect, we set up a model to solve corresponding learning.
At last, this paper uses the RBF neural network that was optimized by the mentioned parallel model to predict the value of some nonlinear functions and the close of several stocks. The result shows that the efficiency and precision of prediction for clean data are satisfactory. Although there are some errors in the prediction of noisy and chaotic data, the result is acceptable.
引文
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