Three-dimensional ISAR imaging: a review

Three-dimensional (3D) inverse synthetic aperture radar (ISAR) imaging has been proven feasible by combining traditional ISAR imaging and interferometry. Such technique, namely inteferometric ISAR (In-ISAR), allows for the main target scattering centres to be mapped into a 3D spatial domain as point clouds. Specifically, the use of an In-ISAR system can overcome the main geometrical interpretation issues imposed by the monostatic acquisition geometry as the problem of cross-range scaling and unknown image projection plane (IPP). However, some issues remain such as scatterer scintillation, shadowing effects, poor SNR etc., which limit the effectiveness of 3D imaging. A solution to such unsolved issues can be found in the use of multiple 3D views, which can be obtained exploiting either multi-temporal or multi-perspective configurations or a combination of both. This study aims to review the main concepts to produce multi-view 3D ISAR images by using In-ISAR systems also presenting real data collected with a multi-static In-ISAR system

Proportional similarity-based Openmax classifier for open set recognition in SAR images

Most of the existing Non-Cooperative Target Recognition (NCTR) systems follow the “closed world” assumption, i.e., they only work with what was previously observed. Nevertheless, the real world is relatively “open” in the sense that the knowledge of the environment is incomplete. Therefore, unknown targets can feed the recognition system at any time while it is operational. Addressing this issue, the Openmax classifier has been recently proposed in the optical domain to make convolutional neural networks (CNN) able to reject unknown targets. There are some fundamental limitations in the Openmax classifier that can end up with two potential errors: (1) rejecting a known target and (2) classifying an unknown target. In this paper, we propose a new classifier to increase the robustness and accuracy. The proposed classifier, which is inspired by the limitations of the Openmax classifier, is based on proportional similarity between the test image and different training classes. We evaluate our method by radar images of man-made targets from the Moving and Stationary Target Acquisition and Recognition (MSTAR) dataset. Moreover, a more in-depth discussion on the Openmax hyper-parameters and a detailed description of the Openmax functioning are given

Compressive sensing for interferometric inverse synthetic aperture radar applications

The applicability of interferometric inverse synthetic aperture radar (InISAR) techniques to images reconstructed via compressive sensing (CS)-based algorithms is investigated. Specifically, the three-dimensional (3D) reconstruction algorithm is applied after exploiting CS for data compression and image reconstruction. The InISAR signal model is derived and formalised in a CS framework. A comparison between conventional CS reconstruction and global sparsity constrained reconstruction techniques is performed for different compression rates and different signal-to-noise ratio conditions. Performances on the 2D and 3D reconstructions are evaluated. Results obtained on real data acquired during the NATO-SET 196 trial are shown

Non-traumatic splenic rupture on dual antiplatelet therapy with aspirin and ticagrelor after stenting for acute coronary syndrome

AbstractWe report a case of non-traumatic splenic rupture in a 57-year-old man on dual antiplatelet therapy (DAPT) with aspirin and ticagrelor, seven months after percutaneous coronary intervention and drug-eluting stent implantation for non-ST elevation myocardial infarction. No splenic abnormalities were found at histopathological analysis after splenectomy, and no history of recent trauma was reported. Once restarted, DAPT after splenectomy, assessment of platelet function was performed by light transmittance aggregometry, showing a profound inhibition of platelet function by adenosine diphosphate, arachidonic acid, and collagen. Taking into account the bleeding risk associated with low on-treatment platelet reactivity, and to switch the patient from ticagrelor to a less potent P2Y12 inhibitor such as clopidogrel, cytochrome P450, genetic polymorphisms accounting for clopidogrel response variability were analyzed. The polymorphisms associated with lower response (CYP2C19*2, CYP2C19*3) were absent. Therefore, ticagrelor was withdrawn, and DAPT was continued with aspirin and clopidogrel. Rupture of the spleen may occur in the absence of major trauma or previous splenic diseases, and could be a complication of antithrombotic treatments. Moreover, low on-treatment platelet reactivity during DAPT is emerging as a possible risk factor for bleeding complications, so underlining the usefulness of assessing platelet function in special conditions to ensure that the patient receives the best tailored antiplatelet therapy.<Learning objective: Non-traumatic splenic rupture is a rare event, and is more often associated with pre-existing splenic abnormalities. However, it may be also a complication of medical treatments, especially with antithrombotic drugs. Low on-treatment platelet reactivity is emerging as a possible risk factor for bleeding complications; therefore, assessing platelet function in special conditions could be useful to ensure the patient receives the best-tailored antiplatelet therapy.

Image Based Robust Target Classification For Passive ISAR

This paper presents an automatic and robust, image feature-based target extraction, and classification method for multistatic passive inverse synthetic aperture radar range/cross-range images. The method can be used as a standalone solution or for augmenting classical signal processing approaches. By extracting textural, directional, and edge information as low-level features, a fused saliency map is calculated for the images and used for target detection. The proposed method uses the contour and the size of the detected targets for classification, is lightweight, fast, and easy to extend. The performance of the approach is compared with machine learning methods and extensively evaluated on real target images

O conceito de proporcionalidade direta de alunos brasileiros de 16 -17 anos na perspectiva dos três mundos da matemática

Teve-se por objetivo investigar as definições de conceito e as imagens de conceito de proporcionalidade direta de um grupo de alunos brasileiros do último ano do Ensino Médio (16-17 anos de idade) de uma escola pública do Estado de São Paulo. Escolheu-se os três mundos da matemática para elaborar e analisar as questões do diagnóstico e buscou-se respostas para duas questões: Qual a definição de conceito de proporcionalidade direta de alunos do Ensino Médio? Com que características, entre formais, simbólicas e corporificadas, trabalham questionamentos que envolvem a proporcionalidade direta? Verificou-se que as definições de conceito e as resoluções dadas aos problemas propostos têm essencialmente características corporificadas; não apresentam características simbólicas; poucos explicitam características formais. Conclui-se que esses participantes não transitaram pelos Três Mundos da Matemática e nem desenvolveram o pensamento proporcional

O conceito de proporcionalidade direta de alunos brasileiros de 16-17 anos na perspectiva dos três mundos da matemática

Teve-se por objetivo investigar as definições de conceito e as imagens de conceito de proporcionalidade direta de um grupo de alunos brasileiros do último ano do ensino médio (16-17 anos de idade) de uma escola pública do Estado de São Paulo. Escolheu-se os Três Mundos da Matemática para elaborar e analisar as questões do diagnóstico e buscou-se respostas para duas questões: Qual a definição de conceito de proporcionalidade direta de alunos do ensino médio? Com que características, entre formais, simbólicas e corporificadas, trabalham questionamentos que envolvem a proporcionalidade direta? Verificou-se que as definições de conceito e as resoluções dadas aos problemas propostos têm essencialmente características corporificadas; não apresentam características simbólicas; poucos explicitam características formais. Conclui-se que esses participantes não transitaram pelos três mundos da matemática e nem desenvolveram o pensamento proporcional

The new engineering geological map (carta litotecnica) of Tuscany (Italy)

Municipal administrations in Italy must be provided with thematic maps and documentation which describe the geological, geomorphological, lithological, hydrogeological and hydraulic characters useful to manage spatial planning issues. Among these documents, a “Lithotechnical” (or “Lithological-Technical”) map is drawn up, generally at the scale of 1:10,000, by organizing the geological formations into lithotechnical units according to their lithological and physical-mechanical properties. Often, this map also integrates the results of previous field and borehole investigations. However, this map is characterized by a certain degree of subjectivity because it is supported by few specific quantitative data. We present a new method for the regional scale engineering geological classification of sub-surface rock and soil masses obtained by integrating the geological map at the scale of 1:10,000 as a reference document, with a large set of data obtained through the collection and processing of new lithological and physical-mechanical observations and measurements of the outcropping geological formations. The adopted procedure involves both the extensive in situ use of the Schmidt's hammer and the execution of laboratory tests, such as the Slake Durability Test (Franklin &amp; Chandra, 1972) and the determination of the rock unit weight. These tools and tests allow us to acquire a large set of quantitative in situ and laboratory data with known repeatability to obtain a regional scale GIS database providing the classification of the lithological and physical-mechanical characteristics of a wide range of geological formations. As a first step, each outcrop is classified according to a new engineering geological nomenclature system described by the code XXv[y]_[Z] whose values are obtained by integrating: i) a lithological parameter XXv evaluated from both typical characters of the geological formations under analysis and outcrop observations; ii) an engineering geological parameter [y] obtained by the results of the Slake Durability Test; iii) an engineering geological parameter [Z] (Rockmass Quality Index - RQI) evaluated at the outcrop scale on the basis of a large set of sclerometric measurements. The results of outcrop classification are stored into a point topology GIS dataset and are then processed and spatialized in order to assign the XXv[y]_[Z] code to the geological formations, thus obtaining the new engineering geological map. Within the framework of research agreements among Regione Toscana administration, the Consorzio LaMMA, the CNRIGG and the Department of Earth, Environmental and Physical Sciences of the University of Siena, the latter being the leader for their implementation, more than 300 geological formations were analysed and classified, and the new engineering geological GIS map was realized in Tuscany for the provinces of Arezzo, Florence, Lucca, Massa-Carrara, Pistoia, Prato and Siena (ca. 15,000 km2)

A Transição das Razões para as Funções Trigonométricas

Nossa motivação surgiu da constatação de que uma das dificuldades, no estudo das funções trigonométricas, é a compreensão de conceitos como o do ciclo trigonométrico e da medida de um ângulo em radianos. Nosso objetivo foi investigar a contribuição de um ensino apoiado em construções com uma geometria dinâmica e em materiais concretos. Baseados na Teoria da Aprendizagem Significativa, escolhemos os conceitos subsunçores relacionados à definição da função seno e aplicamos uma intervenção, com base no Design Based Research, num trabalho em quatro sessões com nove alunos de uma turma de Licenciatura em Matemática. Para elaborar as atividades, consideramos o desenvolvimento histórico de conceitos da Trigonometria e as recomendações dos Parâmetros Curriculares Nacionais. Ao final da intervenção, verificamos que esta não foi suficiente para uma aprendizagem significativa desses conceitos; contudo, observamos que todos os participantes conseguiram construir uma tabela e um gráfico de uma função periódica e, para dois deles, esse gráfico é o da função seno