Nonnegative matrix factorizations (NMF) have recently assumed an important role in several fields, such as pattern recognition, automated image exploitation, data clustering and so on. They represent a peculiar tool adopted to obtain a reduced representation of multivariate data by using additive components only, in order to learn parts-based representations of data. All algorithms for computin...

We train the wavelet packet multi-layer perceptron neural network (WP-MLP) by backpropagation for time series prediction. Weights in the backpropagation algorithm are usually initialized with small random values. If the random initial weights happen to be far from a good solution or they are near a poor local optimum, training may take a long time or get trap in the local optimum. Proper weight...

Activation function is crucial to the recent successes of neural network. In this paper, we propose a new activation function that generalizes and unifies the rectified and exponential linear units. The proposed method, named MPELU, has the advantages of PReLU and ELU. We show that by introducing learnable parameters like PReLU, MPELU provides better generalization capability than PReLU and ELU...

The aim of this paper is to present a new proposal for Cluster Analysis based on a Greedy Randomized Adaptive Search Procedure (GRASP), with the objective of overcoming the convergence to a local solution. It uses a probabilistic greedy Kaufman initialization method for getting initial solutions and the K-Means algorithm as a local search algorithm. The new proposal will become a new initializa...

Applying k-Means to minimize the sum of the intra-cluster variances is the most popular clustering approach. However, after a bad initialization, poor local optima can be easily obtained. To tackle the initialization problem of k-Means, we propose the MinMax k-Means algorithm, a method that assigns weights to the clusters relative to their variance and optimizes a weighted version of the k-Mean...