A combined measure for quantifying and qualifying the topology preservation of growing self-organizing maps

The Self-OrganizingMap (SOM) is a neural network model that performs an ordered projection of a high dimensional input space in a low-dimensional topological structure. The process in which such mapping is formed is defined by the SOM algorithm, which is a competitive, unsupervised and nonparametric method, since it does not make any assumption about the input data distribution. The feature maps provided by this algorithm have been successfully applied for vector quantization, clustering and high dimensional data visualization processes. However, the initialization of the network topology and the selection of the SOM training parameters are two difficult tasks caused by the unknown distribution of the input signals. A misconfiguration of these parameters can generate a feature map of low-quality, so it is necessary to have some measure of the degree of adaptation of the SOM network to the input data model. The topologypreservation is the most common concept used to implement this measure. Several qualitative and quantitative methods have been proposed for measuring the degree of SOM topologypreservation, particularly using Kohonen's model. In this work, two methods for measuring the topologypreservation of the Growing Cell Structures (GCSs) model are proposed: the topographic function and the topology preserving ma

Uso de Redes Neuronales Autoorganizativas Dinámicas no Supervisadas para la Discriminación de tipos de aguas en Lagos.

Las técnicas de clasificación supervisadas aplicadas a imágenes de satélite requieren la selección de muestras representativas de los distintos tipos de clases de cubiertas presentes en la imagen a analizar. El proceso de selección de áreas y su categorización son trabajos que habitualmente se realizan de manera manual por un experto o bien mediante campañas de campo. Para el caso particular de clasificación de imágenes con cubiertas acuosas con diferentes características, hay tres aspectos muy importantes a considerar; en primer lugar, la baja separabilidad de las respuestas espectrales de cada una de las clases de aguas; en segundo lugar, el hecho de que para mejorar los resultados sea necesario trabajar con imágenes de alta resolución, lo que implica que para lagos de tamaños medios y grande el volumen de datos es muy elevado y consecuentemente se requieren una gran cantidad de muestras de entrenamiento; finalmente, cabe destacar el alto costo y complejidad de las tomas de datos en terreno

Suitability of Using Self-Organizing Neural Networks in Configuring P-System Communications Architectures

Nowadays, it is possible to find out different viable architectures that implements P Systems in a distributed cluster of processors. These proposed architectures have reached a certain compromise between the massively parallelism character of the system and the evolution step times. They are based in the distribution of several membranes in each processor, the use of proxies to control the communication between membranes and mainly, the suitable distribution of the architecture in a balanced tree of processors. For a given P-system and K processors, there exists a great volume of possible distributions of membranes over these. The main disadvantage related with these architectures is focused in the selection of the distribution of membranes that minimizes the external communications between them and maximizes the parallelism grade. In this paper, we suggest the use of Self-Organizing Neural Networks (SONN) with growing capability to help in this selection process for a given P-system

Growing Cell Structures Neural Networks for Designing Spectral Indexes

Remote sensing can be defined as the technique that facilitates the acquisition of land surface data without contact with the material object of observation. The development of tools for analyzing and processing multispectral images captured by sensors aboard satellites has provided the automation of tasks that could not be possible otherwise. The main problem related with this discipline is the large volume of data of multidimensional nature that must be handled. The concept of spectral index emerged as an idea to reduce the number of dimensions to one, and thus facilitate the study of different features associated to the types of land cover categories that exhibits a multispectral image. Formally, a spectral index is defined as a combination of spectral bands whose function is to enhance the contribution of one type of land cover mitigating the rest of covers. In this work a no-supervised methodology to analyze and discover spectral indexes based on growing self-organizing neural network (GCS-Growing Cell Structures) is presented