Spectral-spatial classification of hyperspectral images: three tricks and a new supervised learning setting

Spectral-spatial classification of hyperspectral images has been the subject of many studies in recent years. In the presence of only very few labeled pixels, this task becomes challenging. In this paper we address the following two research questions: 1) Can a simple neural network with just a single hidden layer achieve state of the art performance in the presence of few labeled pixels? 2) How is the performance of hyperspectral image classification methods affected when using disjoint train and test sets? We give a positive answer to the first question by using three tricks within a very basic shallow Convolutional Neural Network (CNN) architecture: a tailored loss function, and smooth- and label-based data augmentation. The tailored loss function enforces that neighborhood wavelengths have similar contributions to the features generated during training. A new label-based technique here proposed favors selection of pixels in smaller classes, which is beneficial in the presence of very few labeled pixels and skewed class distributions. To address the second question, we introduce a new sampling procedure to generate disjoint train and test set. Then the train set is used to obtain the CNN model, which is then applied to pixels in the test set to estimate their labels. We assess the efficacy of the simple neural network method on five publicly available hyperspectral images. On these images our method significantly outperforms considered baselines. Notably, with just 1% of labeled pixels per class, on these datasets our method achieves an accuracy that goes from 86.42% (challenging dataset) to 99.52% (easy dataset). Furthermore we show that the simple neural network method improves over other baselines in the new challenging supervised setting. Our analysis substantiates the highly beneficial effect of using the entire image (so train and test data) for constructing a model.Comment: Remote Sensing 201

Su alteza Imperial

El artículo analiza la historia del obelisco de Axum y de su reciente restitución a Etiopía en términos del valor político de la memoria ligada a un objeto patrimonial controvertido. Pensando al "olvido" siguiendo los estudios de Lotman, el articulo entreteje un análisis semiótico sobre la sintaxis urbana y de instalación del obelisco en Roma, a través de las varias risemantizaciones que la estela ha experimentado durante sus casi setenta años vividos en Italia.The article analyzes the history of the Axum obelisk and its recent restitution to Ethiopia in terms of the political value of the memory linked to a controversial asset." Thinking of "forgetfulness" like Lotman's studies, the article weaves a semiotic analysis on the urban syntax and installation of the obelisk in Rome through the various re-sowings that the stele has experienced during its almost 70 years lived in Italy

Electro-mechanical properties of multilayer graphene-based polymeric composite obtained through a capillary rise method

A new sensor made of a vinyl-ester polymer composite filled with multilayer graphene nanoplatelets (MLG) is produced through an innovative capillary rise method for application in strain sensing and structural health monitoring. The new sensor is characterized by high stability of the piezoresistive response under quasi-static consecutive loading/unloading cycles and monotonic tests. This is due to the peculiarity of the fabrication process that ensures a smooth and clean surface of the sensor, without the presence of filler agglomerates acting as micro- or macro-sized defects in the composite

Electromagnetic and electromechanical applications of graphene-based materials

This volume contains the extended abstracts of the contributions presented at the workshop Nanoscale Excitations in Emergent Materials (NEEM 2015) held in Rome from 12 to 14 October 2015, an event organized and supported in the framework of the Bilateral Cooperation Agreement between Italy and India within the project of major relevance "Investigating local structure and magnetism of cobalt nano-structures", funded by the Italian Ministry of Foreign Affairs and the Department of Science and Technology in India

Manufacture and electromechanical characterization of highly conductive multilayer-graphene/polydimethylsiloxane flexible paper

Multilayer graphene (MLG) micro- and nanosheets have been investigated for use as nanofiller in polymer composite in order to obtain multifunctional materials with enhanced electrical conductivity and mechanical properties. In order to take advantage of the conductivity properties of MLG sheets, a large amount of nanofiller should be used. Although, increasing filler loading alters the mechanical properties of the composite because of serious filler agglomeration. It has been shown that a promising approach to realize electrically conductive light-weight composite is to incorporate an electrically conductive graphene paper (GP), obtained by vacuum filtration of a nanofillers suspension, into the polymer matrix. One advantage of infiltrating the GP with polymer is that the tensile modulus of the composite can be greatly improved as compared with either GP or neat polymer, without weakening the electrical properties of the highly continuous nanofillers network formed in the paper making process. In this work we present experimental results related to the fabrication process and the electromechanical behaviour of a free standing, highly-conductive MLG paper impregnated with polydimethylsiloxane (PDMS)

La Rome des Français au temps des Lumières par G. Montègre

compte-rendu de Luca Acquarelli, in Studi Culturali, n°2, p. 354-356

Au prisme du figural : Le sens des images entre forme et force

L'objectif commun qui anime les articles de ce livre est d'aborder la question du sens des images à partir de la tension qu'il y a entre leurs formes et leurs forces. Ces deux termes ont une longue tradition dans les disciplines ayant parmi leurs objectifs l'analyse du sens des images. Ils ont inspiré un second couple de notions souvent utilisées dans le jargon des théories de l'images : le figuratif et le figural. Au croisement de plusieurs disciplines, de la psychanalyse à l'histoire de l'art et de l'esthétique à la phénoménologie, la philosophie, la morphologie et la sémiotique, ces quatre concepts ont ouvert des pistes de travail au cœur d'une recherche sur le sens et la subjectivité. Ils ont surtout une valeur relationnelle, c'est-à-dire qu'ils déploient toute leur opérativité lorsqu'ils se rencontrent, dans une tension réciproque. Ainsi, un rapprochement entre ces termes ne représente pas une mise en parallèle, mais plutôt un ensemble problématique, c'est-à-dire un ensemble de catégories théoriques traversé par plusieurs disciplines, qui, dans le cas de ce livre, est interrogé par le biais d'un débat sur les sens des images et de leurs agencements. En faisant dialoguer des approches plurielles de l'image, tout en préservant l'autonomie des démarches d'analyse, ce débat pousse les disciplines à sortir de leurs certitudes pour faire face à des questions renouvelées

Introduction

Ce livre est le résultat de la journée d’étude intitulée « Le sens des images entre formes et forces. Du figuratif au figural et retour : analyses d’objets », organisée par le CEHTA (Centre d’Histoire et de Théorie des Arts) à l’Institut National d’Histoire de l’Art en avril 2012. Les débats et les échanges consécutifs à cette journée ont convaincu les intervenants de la vivacité des enjeux théoriques et des axes d’analyse suscités par la rencontre, et nous nous sommes accordés pour les réuni..

Electro-Mechanical Properties of Multilayer Graphene-Based Polymeric Composite Obtained through a Capillary Rise Method

A new sensor made of a vinyl-ester polymer composite filled with multilayer graphene nanoplatelets (MLG) is produced through an innovative capillary rise method for application in strain sensing and structural health monitoring. The new sensor is characterized by high stability of the piezoresistive response under quasi-static consecutive loading/unloading cycles and monotonic tests. This is due to the peculiarity of the fabrication process that ensures a smooth and clean surface of the sensor, without the presence of filler agglomerates acting as micro- or macro-sized defects in the composite