极限学习机类不平衡数据学习算法研究

尽管极限学习机因具有快速、简单、易实现及普适的逼近能力等特点被广泛应用于分类、回归及特征学习问题,但是,极限学习机同其他标准分类方法一样将最大化各类总分类性能作为算法的优化目标,因此,在实际应用中遇到数据样本分布不平衡时,算法对大类样本具有性能偏向性。针对极限学习机类不平衡学习问题的研究起步晚,算法少的问题,在介绍了极限学习机类不平衡数据学习研究现状,极限学习机类不平衡数据学习的典型算法-加权极限学习机及其改进算法的基础上,提出一种不需要对原始不平衡样本进行处理的Adaboost提升的加权极限学习机,通过在15个UCI不平衡数据集进行分析实验,实验结果表明提出的算法具有更好的分类性能。     

Extreme learning machine for structured output spaces

Recently, extreme learning machine (ELM) has attracted increasing attention due to its successful applications in classification, regression, and ranking. Normally, the desired output of the learning system using these machine learning techniques is a simple scalar output. However, there are many applications in machine learning which require more complex output rather than a simple scalar one. Therefore, structured output is used for such applications where the system is trained to predict structured output instead of simple one. Previously, support vector machine (SVM) has been introduced for structured output learning in various applications. However, from machine learning point of view, ELM is known to offer better generalization performance compared to other learning techniques. In this study, we extend ELM to more generalized framework to handle complex outputs where simple outputs are considered as special cases of it. Besides the good generalization property of ELM, the resulting model will possesses rich internal structure that reflects task-specific relations and constraints. The experimental results show that structured ELM achieves similar (for binary problems) or better (for multi-class problems) generalization performance when compared to ELM. Moreover, as verified by the simulation results, structured ELM has comparable or better precision performance with structured SVM when tested for more complex output such as object localization problem on PASCAL VOC2006. Also, the investigation on parameter selections is presented and discussed for all problems.

     

A machine learning method for extracting symbolic knowledge from recurrent neural networks

Neural networks do not readily provide an explanation of the knowledge stored in their weights as part of their information processing. Until recently, neural networks were considered to be black boxes, with the knowledge stored in their weights not readily accessible. Since then, research has resulted in a number of algorithms for extracting knowledge in symbolic form from trained neural networks. This article addresses the extraction of knowledge in symbolic form from recurrent neural networks trained to behave like deterministic finite-state automata (DFAs). To date, methods used to extract knowledge from such networks have relied on the hypothesis that networks' states tend to cluster and that clusters of network states correspond to DFA states. The computational complexity of such a cluster analysis has led to heuristics that either limit the number of clusters that may form during training or limit the exploration of the space of hidden recurrent state neurons. These limitations, while necessary, may lead to decreased fidelity, in which the extracted knowledge may not model the true behavior of a trained network, perhaps not even for the training set. The method proposed here uses a polynomial time, symbolic learning algorithm to infer DFAs solely from the observation of a trained network's input-output behavior. Thus, this method has the potential to increase the fidelity of the extracted knowledge.     

Extreme learning machine model for water network management

Neural Computing and Applications - A novel failure rate prediction model is developed by the extreme learning machine (ELM) to provide key information needed for optimum ongoing...     

A hybrid learning algorithm for a class of interval type-2 fuzzy neural networks

In real life, information about the world is uncertain and imprecise. The cause of this uncertainty is due to: deficiencies on given information, the fuzzy nature of our perception of events and objects, and on the limitations of the models we use to explain the world. The development of new methods for dealing with information with uncertainty is crucial for solving real life problems. In this paper three interval type-2 fuzzy neural network (IT2FNN) architectures are proposed, with hybrid learning algorithm techniques (gradient descent backpropagation and gradient descent with adaptive learning rate backpropagation). At the antecedents layer, a interval type-2 fuzzy neuron (IT2FN) model is used, and in case of the consequents layer an interval type-1 fuzzy neuron model (IT1FN), in order to fuzzify the rule’s antecedents and consequents of an interval type-2 Takagi-Sugeno-Kang fuzzy inference system (IT2-TSK-FIS). IT2-TSK-FIS is integrated in an adaptive neural network, in order to take advantage the best of both models. This provides a high order intuitive mechanism for representing imperfect information by means of use of fuzzy If-Then rules, in addition to handling uncertainty and imprecision. On the other hand, neural networks are highly adaptable, with learning and generalization capabilities. Experimental results are divided in two kinds: in the first one a non-linear identification problem for control systems is simulated, here a comparative analysis of learning architectures IT2FNN and ANFIS is done. For the second kind, a non-linear Mackey-Glass chaotic time series prediction problem with uncertainty sources is studied. Finally, IT2FNN proved to be more efficient mechanism for modeling real-world problems.     

Extreme learning machine for regression and multiclass classification

Due to the simplicity of their implementations, least square support vector machine (LS-SVM) and proximal support vector machine (PSVM) have been widely used in binary classification applications. The conventional LS-SVM and PSVM cannot be used in regression and multiclass classification applications directly, although variants of LS-SVM and PSVM have been proposed to handle such cases. This paper shows that both LS-SVM and PSVM can be simplified further and a unified learning framework of LS-SVM, PSVM, and other regularization algorithms referred to extreme learning machine (ELM) can be built. ELM works for the "generalized" single-hidden-layer feedforward networks (SLFNs), but the hidden layer (or called feature mapping) in ELM need not be tuned. Such SLFNs include but are not limited to SVM, polynomial network, and the conventional feedforward neural networks. This paper shows the following: 1) ELM provides a unified learning platform with a widespread type of feature mappings and can be applied in regression and multiclass classification applications directly; 2) from the optimization method point of view, ELM has milder optimization constraints compared to LS-SVM and PSVM; 3) in theory, compared to ELM, LS-SVM and PSVM achieve suboptimal solutions and require higher computational complexity; and 4) in theory, ELM can approximate any target continuous function and classify any disjoint regions. As verified by the simulation results, ELM tends to have better scalability and achieve similar (for regression and binary class cases) or much better (for multiclass cases) generalization performance at much faster learning speed (up to thousands times) than traditional SVM and LS-SVM.     

一种基于鲁棒估计的极限学习机方法

极限学习机(ELM)是一种单隐层前馈神经网络(single-hidden layer feedforward neural networks,SLFNs),它相较于传统神经网络算法来说结构简单,具有较快的学习速度和良好的泛化性能等优点。ELM的输出权值是由最小二乘法(least square,LE)计算得出,然而经典的LS估计的抗差能力较差,容易夸大离群点和噪声的影响,从而造成训练出的参数模型不准确甚至得到完全错误的结果。为了解决此问题,提出一种基于M估计的采用加权最小二乘方法来取代最小二乘法计算输出权值的鲁棒极限学习机算法(RBELM),通过对多个数据集进行回归和分类分析实验,结果表明,该方法能够有效降低异常值的影响,具有良好的抗差能力。     

Extreme learning machine and its applications

Recently, a novel learning algorithm for single-hidden-layer feedforward neural networks (SLFNs) named extreme learning machine (ELM) was proposed by Huang et al. The essence of ELM is that the learning parameters of hidden nodes, including input weights and biases, are randomly assigned and need not be tuned while the output weights can be analytically determined by the simple generalized inverse operation. The only parameter needed to be defined is the number of hidden nodes. Compared with other traditional learning algorithms for SLFNs, ELM provides extremely faster learning speed, better generalization performance and with least human intervention. This paper firstly introduces a brief review of ELM, describing the principle and algorithm of ELM. Then, we put emphasis on the improved methods or the typical variants of ELM, especially on incremental ELM, pruning ELM, error-minimized ELM, two-stage ELM, online sequential ELM, evolutionary ELM, voting-based ELM, ordinal ELM, fully complex ELM, and symmetric ELM. Next, the paper summarized the applications of ELM on classification, regression, function approximation, pattern recognition, forecasting and diagnosis, and so on. In the last, the paper discussed several open issues of ELM, which may be worthy of exploring in the future.     

Adaptive hybrid learning for neural networks

A robust locally adaptive learning algorithm is developed via two enhancements of the Resilient Propagation (RPROP) method. Remaining drawbacks of the gradient-based approach are addressed by hybridization with gradient-independent Local Search. Finally, a global optimization method based on recursion of the hybrid is constructed, making use of tabu neighborhoods to accelerate the search for minima through diversification. Enhanced RPROP is shown to be faster and more accurate than the standard RPROP in solving classification tasks based on natural data sets taken from the UCI repository of machine learning databases. Furthermore, the use of Local Search is shown to improve Enhanced RPROP by solving the same classification tasks as part of the global optimization method.     

Extreme learning machine terrain-based navigation for unmanned aerial vehicles

Unmanned aerial vehicles (UAVs) rely on global positioning system (GPS) information to ascertain its position for navigation during mission execution. In the absence of GPS information, the capability of a UAV to carry out its intended mission is hindered. In this paper, we learn alternative means for UAVs to derive real-time positional reference information so as to ensure the continuity of the mission. We present extreme learning machine as a mechanism for learning the stored digital elevation information so as to aid UAVs to navigate through terrain without the need for GPS. The proposed algorithm accommodates the need of the on-line implementation by supporting multi-resolution terrain access, thus capable of generating an immediate path with high accuracy within the allowable time scale. Numerical tests have demonstrated the potential benefits of the approach.     

触觉手势情感识别的超限学习方法

为了解决声音和图像情感识别的不足,提出一种新的情感识别方式:触觉情感识别。对CoST（corpus of social touch）数据集进行了一系列触觉情感识别研究,对CoST数据集进行数据预处理,提出一些关于触觉情感识别的特征。利用极限学习机分类器探究不同手势下的情感识别,对14种手势下的3种情感（温柔、正常、暴躁）进行识别,准确度较高,且识别速度快识别时间短。结果表明,手势的不同会影响情感识别的准确率,其中手势“stroke”的识别效果在不同分类器下的分类精度均为最高,且有较好的分类精度,达到72.07%;极限学习机作为触觉情感识别的分类器,具有较好的分类效果,识别速度快;有的手势本身对应着某种情感,从而影响分类结果。     

Extreme learning machine with errors in variables

Extreme learning machine (ELM) is widely used in training single-hidden layer feedforward neural networks (SLFNs) because of its good generalization and fast speed. However, most improved ELMs usually discuss the approximation problem for sample data with output noises, not for sample data with noises both in input and output values, i.e., error-in-variable (EIV) model. In this paper, a novel algorithm, called (regularized) TLS-ELM, is proposed to approximate the EIV model based on ELM and total least squares (TLS) method. The proposed TLS-ELM uses the idea of ELM to choose the hidden weights, and applies TLS method to determine the output weights. Furthermore, the perturbation quantities of hidden output matrix and observed values are given simultaneously. Comparison experiments of our proposed TLS-ELM with least square method, TLS method and ELM show that our proposed TLS-ELM has better accuracy and less training time.     

逐层可加的急速学习机

已有的急速学习机（Extreme Learning Machine）的学习精度受隐节点数目的影响很大。无论是已提出的单隐层急速学习机还是多隐层神经网络,都是先确定隐藏层数,再通过增加每一层的神经元个数来提高精度。但当训练集规模很大时,往往需要引入很多的隐节点,导致违逆矩阵计算复杂度大,从而不利于学习效率的提高。提出逐层可加的急速学习机MHL-ELM（Extreme Learning Machine with Incremental Hidden Layers）,其思想是首先对当前隐藏层神经元（数目不大且不寻优,因而复杂度小）的权值进行随机赋值,用ELM思想求出逼近误差;若误差达不到要求,再增加一个隐含层。然后运用ELM的思想对当前隐含层优化。逐渐增加隐含层,直至满足误差精度为止。除此以外,MHL-ELM的算法复杂度为[l=1MO(N3l)]。实验使用10个UCI,keel真实数据集,通过与BP,OP-ELM等传统方法进行比较,表明MHL-ELM学习方法具有更好的泛化性,在学习精度和学习速度方面都有很大的提升。     

基于共轭梯度的极速学习机

极速学习机(ELM)由于具有较快的训练速度和较好的泛化能力而被广泛的应用到很多的领域,然而在计算数据样例个数较大的情况下,它的训练速度就会下降,甚至会出现程序报错,因此提出在ELM模型中用改进的共轭梯度算法代替广义逆的计算方法。实验结果表明,与求逆矩阵的ELM算法相比,在同等泛化精度的条件下,共轭梯度ELM有着更快的训练速度。通过研究发现:基于共轭梯度的极速学习机算法不需要计算一个大型矩阵的广义逆,而大部分广义逆的计算依赖于矩阵的奇异值分解(SVD),但这种奇异值分解对于阶数很高的矩阵具有很低的效率;因为已经证明共轭梯度算法可通过有限步迭代找到其解,所以基于共轭剃度的极速学习机有着较高的训练速度,而且也比较适用于处理大数据。     

改进人工蜂群优化的极限学习机

针对极限学习机(ELM)在训练过程中需要大量隐含层节点的问题,提出了差分进化与克隆算法改进人工蜂群优化的极限学习机(DECABC-ELM),在人工蜂群算法的基础上,引入了差分进化算法的差分变异算子和免疫克隆算法的克隆扩增算子,改进了人工蜂群收敛速度慢等缺点,使用改进的人工蜂群算法计算ELM的隐含层节点参数.将算法应用于回归和分类数据集,并与其他算法进行比较,获得了良好的效果.     

带有时滞的随机区间Hopfield神经网络的指数稳定性

讨论了带有可变时滞的随机区间Hopfield神经网络的指数稳定性, 利用It^o公式和Lyapunov函数, 得到了几个关于其指数稳定时滞无关和时滞相关的充分性条件, 推广了现有文献中关于定常时滞随机神经网络及其确定形式的许多结果.     

Randomized neural networks for learning stochastic dependences

We consider the problem of learning the dependence of one random variable on another, from a finite string of independently identically distributed (i.i.d.) copies of the pair. The problem is first converted to that of learning a function of the latter random variable and an independent random variable uniformly distributed on the unit interval. However, this cannot be achieved using the usual function learning techniques because the samples of the uniformly distributed random variables are not available. We propose a novel loss function, the minimizer of which results in an approximation to the needed function. Through successive approximation results (suggested by the proposed loss function), a suitable class of functions represented by combination feedforward neural networks is selected as the class to learn from. These results are also extended for countable as well as continuous state-space Markov chains. The effectiveness of the proposed method is indicated through simulation studies.     

Projection learning algorithm for threshold-controlled neural networks

Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 156–167, July–August 1994.     

Self-supervised role learning for graph neural networks

Knowledge and Information Systems - We present InfoMotif, a new semi-supervised, motif-regularized, learning framework over graphs. We overcome two key limitations of message passing in popular...